CN103219733A - Scattered power generation reactive compensation device and method with harmonic suppression function - Google Patents

Abstract

The invention belongs to the technical field of electric power system automatic control, and in particular relates to a distributed wind power reactive power compensation device and method with a harmonic suppression function. The invention includes an AT hybrid reactive power compensation unit, a centralized control unit and a power supply module. The AT hybrid reactive power compensation unit includes a thyristor-controlled reactor (TCR), an active power filter (APF) and a passive filter. The thyristor-controlled reactor group is connected to the compensation access point between the passive filter group and the grid main line, the active power filter and the passive filter group are connected in series to form a hybrid active filter, and the centralized control unit outputs pulse width modulation The signal and the trigger pulse signal respectively trigger the APF transistor and the thyristors in the thyristor-controlled reactor bank. The invention effectively suppresses the resonance between the passive filter and the power grid, makes the harmonic compensation precision higher, the system responds faster, improves the safety of reactive power compensation, and is economical and practical.

Description

A distributed power generation reactive power compensation device and method with harmonic suppression function

technical field

The invention belongs to the technical field of electric power system automatic control, and in particular relates to a distributed wind power reactive power compensation device and method with a harmonic suppression function.

Background technique

At present, my country's power generation methods have caused great damage to the environment, and the use of decentralized power generation to make full use of the abundant "clean energy" in various places will greatly promote my country's sustainable development.

Distributed power generation itself can generate a large amount of active and reactive power. If these energies can be used reasonably to improve power quality, it will save a lot of equipment investment. However, distributed power generation, especially the relatively mature wind power and solar power generation, has random and instantaneous energy sources, and cannot generate stable active and reactive power. This is equivalent to connecting a large random load to the system. The start-up and shutdown of distributed power generation units will also produce large fluctuations in active and reactive power; these will have a profound impact on the stability of the power system.

The most effective measure to solve the above problems is to perform reactive power compensation at the distributed power generation unit and the grid access point to ensure that the reactive power of the access point is stable within a certain range, so as to reduce the reactive power impact on the grid , so as to give full play to the advantages of the distributed power supply itself and improve the power quality of the power system.

At present, the reactive power compensation method of distributed wind farms mainly adopts the combination of static var compensator (SVC) and fixed capacitor, but the passive filter in SVC has filtering characteristics affected by grid reactance and is prone to parallel resonance with grid reactance The inherent defects of the grid voltage will cause waveform distortion, voltage fluctuation and flicker, etc., which will have a significant negative impact on the distributed power generation system.

Contents of the invention

Aiming at the problem that the passive filter resonates with the grid and generates harmonics in the reactive power compensation of the distributed power generation system, the present invention provides a distributed power generation reactive power compensation device and control method with harmonic suppression function. The reactive power generated by the generator reactive power compensation device is used to suppress the harmonics generated by the system.

The present invention is achieved through the following technical solutions:

A distributed generation reactive power compensation device with harmonic suppression function, comprising: an A-T hybrid reactive power compensation unit, a centralized control unit and a power supply module. The A-T hybrid reactive power compensation unit includes a thyristor-controlled reactor (TCR), an active power filter (APF) and a passive filter. The thyristor-controlled reactor group is connected to the compensation access point between the passive filter group and the grid main line, the active power filter and the passive filter group are connected in series to form a hybrid active filter, and the centralized control unit outputs pulse width modulation The signal and the trigger pulse signal respectively trigger the APF transistor and the thyristors in the thyristor-controlled reactor bank.

The thyristor-controlled reactor group is composed of three groups of thyristor-controlled reactors connected in parallel, and each group of thyristor-controlled reactors is composed of two thyristors connected in parallel and one reactor connected in series; the passive filter group includes three groups of LCs connected in parallel Each branch is composed of three separate LC series branches connected in parallel; the specific connection of the A-T hybrid reactive power compensation unit is: the thyristor control reactor group is connected between the passive filter group and the main line of the power grid The compensation access point, the output end of the active filter is connected to the input end of the passive filter bank through the filter reactance, and the output end of the passive filter bank is connected to the power grid, thereby suppressing the harmonics of the power grid.

The centralized control unit includes a sampling module, a DSP control module, a phase-locked loop circuit module, a pulse generation module, an information feedback and a display module; the specific connection of the centralized control unit is: the voltage and current signals collected from the power grid are connected to the sampling module The input terminal of the sampling module is connected to the input terminal of the DSP control module, the output terminal of the DSP control module is connected to the input terminal of the phase-locked loop circuit module, and the output terminal of the phase-locked loop circuit module is connected to the input terminal of the pulse generation module. The output terminal of the generating module is connected to the input terminal of the thyristor-controlled reactor group and the active power filter, the output terminal of the thyristor-controlled reactor group and the active power filter is connected to the input terminal of the feedback module, and the output terminal of the feedback module is connected to the display module The input terminal of the display module is connected to the input terminal of the DSP control module through the dual-port RAM communication module.

The sampling module includes a precision series voltage transformer TR1102-1C, a current transformer TR0102-2C and a DSP sampling module, and the DSP sampling module includes a signal conditioning circuit and a zero-crossing detection circuit. The high-voltage end of the voltage transformer and current transformer is connected to the power grid, the low-voltage end is connected to the input end of the DSP sampling module, the output end of the signal conditioning circuit is connected to the input end of the zero-crossing detection circuit, and the output end of the zero-crossing detection circuit is used as the output of the sampling module The terminal is connected to the DSP control module; the DSP control module is mainly composed of TMS320F2812 series DSP, and the output terminal of the DSP control module is connected to the input terminal of the pulse generation module. The specific connection of the sampling module is: the high-voltage side of the primary voltage-current transformer is connected to the power grid, the low-voltage side is connected to the input end of the secondary voltage-current transformer, and the output end of the secondary voltage-current transformer is connected to the A/D conversion chip. The input terminal and the output terminal of the A/D conversion chip are connected to the input terminal of the DSP sampling board, and the output terminal of the DSP sampling board is connected to the latch. At the same time, the DSP sampling board exchanges data with the single-chip 80C196 through the dual-port RAM.

The phase-locked loop circuit module includes a zero-crossing detection circuit, a phase-locked loop circuit, a frequency multiplication circuit, a low-pass filter and a voltage-controlled oscillator; the output end of the zero-crossing detection circuit is connected to the input end of the phase-locked loop circuit, and the phase-locked The output end of the loop circuit is connected to the input end of the frequency multiplication circuit, and the frequency multiplication circuit generates sampling narrow pulses to trigger the sampling and holding circuit, so as to realize phase-locked and synchronous sampling. The specific connection of the phase-locked loop circuit module is: the voltage and current signals are connected to the input terminal of the zero-crossing detection circuit, the output terminal of the zero-crossing detection circuit is connected to the input terminal of the phase comparator, and the output terminal of the phase comparator is connected to the low-pass filter. The input terminal and the output terminal of the low-pass filter are connected to the input terminal of the voltage-controlled oscillator, and the output terminal of the voltage-controlled oscillator is connected to a shaping circuit for shaping the input signal.

The pulse generating module includes a synchronous voltage signal limiting circuit, a synchronous shaping circuit, and a pulse generating circuit; the pulse generating circuit includes a pulse opening and blocking circuit, a pulse stretching circuit, and a photoelectric conversion circuit. The front end of the synchronous voltage signal limiting circuit is connected to the DSP control module, the output end is connected to the input end of the synchronous shaping circuit, the output end of the synchronous shaping circuit is connected to the input end of the pulse generating circuit, and the output pulse controls the thyristor to control the reactor group and the active power filter The signal trigger of the device. The specific connection of the pulse generation module is: the output end of the synchronous voltage signal limiting circuit is connected to the input end of the synchronous shaping circuit, the output end of the synchronous shaping circuit is connected to the input end of the 12-bit synchronous counter, and the output end of the 12-bit synchronous counter is connected to the 12-bit synchronous counter. The input end of the comparator, the output end of the 12-bit comparator are connected to the input end of the pulse opening and blocking circuit, the output end of the pulse opening and blocking circuit is connected to the input end of the pulse stretching circuit, the output end of the pulse stretching circuit is connected to the input end of the photoelectric conversion circuit, and the output of the photoelectric conversion circuit terminal control thyristor.

The information feedback and display module includes a high-potential board, a return board and an information display module. The information display module mainly includes an 80C196 single-chip microcomputer, a liquid crystal display module, an external main control human-machine interface module, that is, an external keyboard input and a host computer. The specific connection of the information feedback and display module is: the output end of the thyristor control reactor group and the active power filter is connected to the input end of the high potential board, the output end of the high potential board is connected to the input end of the return board, and the output end of the return board Connect the 80C196 single-chip microcomputer, the output end of the single-chip microcomputer is respectively connected to the liquid crystal display part and the upper computer monitoring module, and the information display module of the keyboard access part communicates with each other through the dual-port RAM and the DSP sampling module.

A control method for harmonic suppression of a distributed power generation reactive power compensation device with a harmonic suppression function, specifically as follows:

Step 1: The sampling module collects the instantaneous three-phase voltage u _a , u _b , u _c and the instantaneous three-phase current i _a , i _b , i _c of the distributed power generation system;

Step 2: Calculation of the control angle of the thyristor: firstly, phase-locking technology is used to detect the three-phase AC signal, including voltage, current and frequency; Operation, and then output the thyristor control angle, in the subsequent feedback part, the photoelectric conversion circuit realizes the output of the thyristor trigger signal and the reception of the status return signal;

Step 3: Generate a trigger pulse: First, the system voltage is detected for zero crossing, and the accumulator is set to reset on the rising edge, so that the rising edge pulse of the zero-crossing detection voltage can reset the accumulator, and accumulate to form a sawtooth wave when it rises next time , compare the triggering angle of the thyristor calculated by the DSP with this sawtooth wave, when the triggering angle of the thyristor is greater than the accumulated value of the accumulator, a rising edge pulse is triggered until the accumulator is reset, thus obtaining a wide pulse; The pulse is too wide, so compare the obtained wide-frequency pulse with the secondary accumulator in the same way, and you can get a narrow pulse signal enough to trigger the thyristor;

Step 4: Control the on-off of the thyristor of the reactive power compensator and the transistor of the active power filter, and perform reactive power compensation and harmonic suppression on the distributed power generation system.

The passive filter bank is composed of three groups of LC parallel branches, each branch is composed of three groups of LC branches in series, and each group of branches is connected in series with a filter capacitor, which is installed at the output contact of the active filter In this way, the harmonic voltage of the node can be reduced, the injection of harmonic current into the power system can be suppressed, and it can also provide sufficient overcapacity compensation for the entire system.

The detection of the three-phase alternating current is specifically carried out as follows:

Step 1: First let the grid voltage be:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ \underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ \underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\end{array}\right]$

In the formula, u _a , u _b , u _c are instantaneous values of three-phase voltage, E _1n represents positive sequence voltage effective value, E _2n represents negative sequence voltage effective value, ω is angular frequency, θ _2n is negative sequence initial phase angle;

Step 2: Transform the abc three-phase to α-β two-phase coordinates of the three-phase voltage in the above formula as follows:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 32</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\end{array}\right]$

u _α and u _β are the corresponding two-phase voltage values under the α-β coordinates, and c ₃₂ is the conversion matrix from abc three-phase to α-β two-phase;

Step 3: Obtain the following matrix from the above formula and matrix c _sc :

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; sc</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ]</span>\\ <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ]</span>\end{array}\right]$

In the above formula:

${\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; sc</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>\end{array}\right]$

sin(ωt+θ) and cos(ωt+θ) are signals generated by a standard sinusoidal power frequency signal generator, and θ is any initial phase angle;

Step 4: Extracting the DC component from the above formula, the following can be obtained:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>\end{array}\right]$

Then the transformed voltage is:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; sc</span>}}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&omega;t</span>}\\ <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&omega;t</span>}\end{array}\right]$

E _s , E _c are the extracted DC components, c _sc ^-1 is the inverse matrix of the conversion matrix, u _sf , u _cf are the converted two-phase voltage values;

Step 5: Calculate the p and q components from the transformed phase voltage u _sf , u _cf and current i _α , i _β , the calculation formula is as follows:

$\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; p</span>}\\ \mathrm{<span\; class="notranslate">\; q</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}& {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}& <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]$

Step 6: Calculate the detection current: the p component gets the corresponding AC component after the neural network filtering algorithm, the q component gets the corresponding negative DC component after the inversion algorithm, and then converts to get the α-β two-phase detection current, the specific formula as follows:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sf"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">sf</figure-callout></span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}& {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}& <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}\end{array}\right]\left[\begin{array}{c}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; p</span>}}\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; q</span>}\end{array}\right]$

is the AC component corresponding to the p component, the instantaneous reactive power detection current i _a , i _b , i _c can be obtained from i _α and i _β through the transformation matrix, and the specific formula is as follows:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}}\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}\\ <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& \frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& <span\; class="notranslate">\; -</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]$

Step 7: Calculate the firing angle α of the thyristor according to the detected current;

When the thyristor is in normal operation, the fundamental current in the system is:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; \&pi;X</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}$

The subscript 1 of the fundamental wave current I represents the first harmonic, which is the fundamental wave; X _L is the reactance, X _L =ωL; U _m is the peak value of the voltage; from this, the trigger angle can be calculated.

The overall optimization algorithm process of the passive filter bank is as follows:

Step 1: System parameter setting, mainly including system reactive power compensation amount, voltage value of passive filter bank and harmonic limit value, etc.; system reactive power compensation amount is Q _SVC =Q ₁ +Q ₂ +...+ Q _h , the voltage and current limits of system harmonics are I _h <I _H , U _h <U _H , I _H and U _H are the maximum limit values of system harmonic current and voltage; Q ₁ , Q ₂ , and Q _h are Reactive power output by each branch; I _h is the system harmonic current, U _h is the system harmonic voltage;

Step 2: Determine the total value Q of reactive power compensation that the actual passive filter bank can provide, and allocate the reactive power compensation of each branch of the passive filter bank according to the ratio of each harmonic current to the total harmonic current Quantity Q _i ;

Step 3: Correct the distribution of reactive power according to the voltage and current harmonic distortion rate and the parallel resonance frequency of the passive filter bank;

,滤波器组内、外谐振频率约束为f_ii

[50h(1+δ_emn),50h(1+δ_emp)]，f_io

[50h(1+δ_emn),50h(1+δ_emp)]；式中U₁为基波电压有效值；h为谐波次数，H为滤波器组数，δ_emn为负最大等效频率偏差，δ_emp为正最大等效频率偏差；The total harmonic distortion rate of the power system is

, the inner and outer resonant frequencies of the filter bank are restricted to f _ii

[50h(1+δ _emn ),50h(1+δ _emp )], f _io

[50h(1+δ _emn ),50h(1+δ _emp )]; where U ₁ is the effective value of the fundamental voltage; h is the harmonic order, H is the number of filter groups, and δ _emn is the negative maximum equivalent frequency Deviation, δ _emp is the positive maximum equivalent frequency deviation;

Step 4: Circularly calculate the parameter values of each branch filter, and judge whether the filter satisfies the conditions of the voltage and current harmonic distortion rate and the internal and external parallel resonance frequency of the passive filter bank. If the conditions are met, then judge the passive filter bank Whether the reactive power output meets the reactive power compensation amount of the actual distributed power generation reactive power compensation device, if the condition is not satisfied, re-correct the harmonic coefficient, return to the reactive power allocation step, and then the reactive power output of the passive filter bank satisfies After the reactive power compensation amount of the actual distributed power generation reactive power compensation device is obtained, the passive filter bank can be operated for reactive power output and harmonic suppression.

Advantage of the present invention and beneficial effect are:

On the basis of the thyristor-controlled reactor group (TCR type), the present invention adds active filters and passive filter groups, and proposes a hybrid compensation device that can perform reactive power compensation and suppress harmonics. The invention uses The new topology replaces the traditional passive filter part, and combined with the TCR dynamic reactive power adjustment capability, it can effectively suppress the resonance between the passive filter and the power grid, making the harmonic compensation more accurate, the system responding faster, and improving The security of reactive power compensation is improved.

1. The thyristor-controlled reactor group and the active filter of the present invention adopt centralized compensation, jointly suppress harmonics, and work in a decentralized manner, that is, both the thyristor-controlled reactor group and the active filter pass through the control unit and pass through the passive filter The group and the control reactor are connected to the power grid to jointly perform reactive power compensation and harmonic suppression, and at the same time constitute two sets of working systems, that is, the reactive power compensator and the active filter can work separately, thus avoiding the simultaneous operation of the two compensation devices If there is a problem and cannot work, the reliability of the work is guaranteed.

2. The control unit of the present invention adopts a set of control units, and a set of control units respectively controls the thyristor control reactor group thyristor and the active filter transistor through two control paths, which reduces unnecessary control devices connected to the power grid, It also makes the control part simple, economical and practical.

3. The active power filter in the A-T hybrid reactive power compensation unit of the present invention is controlled as a harmonic voltage source, which can effectively improve the filtering characteristics of the passive filter and suppress the parallel resonance between the passive filter and the system inductance , so that the reactive power adjustment ability is stronger, and the disadvantage that the reactive power is easy to be reversed at light load is overcome.

4. The detection method of the three-phase alternating current of the present invention adopts an improved p-q detection algorithm, and a neural network algorithm is adopted when calculating the AC component and the DC component, so that the value of the initial phase angle θ of the power frequency signal generator does not affect the final power grid The accuracy of positive sequence voltage phase detection, and eliminates the error that occurs when the grid voltage is asymmetrical.

5. The design of the parameters of the passive filter bank of the present invention considers the optimal distribution of the reactive power compensation of the overall filter bank, and simplifies some high-dimensional and complex constraint conditions as far as possible, so as to avoid the involvement of each filter branch in parameter optimization. Some nonlinear algorithms.

6. In the present invention, the passive filter bank is installed on the node of the nonlinear load in the distributed power generation system, so that the harmonic voltage of the node can be reduced, the injection of harmonic current into the power system can be suppressed, and it can better serve the whole The system provides sufficient overcapacity compensation.

Description of drawings

Fig. 1 is a general structural block diagram of the device of the present invention;

Fig. 2 is A-T hybrid reactive power compensation unit structural diagram among the present invention;

Fig. 3 is a structural diagram of a centralized control unit in the present invention;

Fig. 4 is a schematic diagram of the signal conditioning circuit of the present invention;

Fig. 5 is a structural block diagram of DSP main control board among the present invention;

Fig. 6 is a structural diagram of a phase-locked circuit in the present invention;

Fig. 7 is the wiring diagram of the phase-locked frequency multiplication circuit in the present invention;

Fig. 8 is a structural diagram of trigger pulse formation in the present invention;

Fig. 9 is a synchronous signal forming circuit diagram among the present invention;

Fig. 10 is a trigger pulse generating circuit diagram in the present invention;

Fig. 11 is a pulse stretching circuit diagram in the present invention;

Fig. 12 is a schematic diagram of the power module in the present invention;

Figure 13 is a connection diagram of CY7C133 in the present invention;

Fig. 14 is a schematic diagram showing the connection between the single-chip microcomputer and the host computer in the present invention;

Fig. 15 is a schematic diagram of a matrix keyboard in the present invention;

Fig. 16 is a diagram of a liquid crystal display module in the present invention;

Fig. 17 is a flow chart of the filter bank overall optimization algorithm in the present invention.

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments, but is not limited by the embodiments.

Detailed ways

The present invention is a distributed power generation reactive power compensation device and method with harmonic suppression function. The detailed structure and working principle of the device of the present invention will be explained in conjunction with the embodiment. The embodiment takes the 110V static reactive power compensation experimental platform in the laboratory as an example. , the experimental platform static reactive power compensation device SVC is TCR+FC type, in addition to compensating static reactive power and three-phase imbalance, it can also suppress the harmonics generated by the distributed wind power system.

The distributed power generation reactive power compensation device with harmonic suppression function of the present invention mainly includes: A-T hybrid reactive power compensation unit and centralized control unit. The A-T hybrid reactive power compensation unit includes thyristor controlled reactor group (TCR), active Source power filters (APF) and passive filter banks. The thyristor-controlled reactor group is connected to the compensation access point between the passive filter group and the grid main line, the active power filter and the passive filter group are connected in series to form a hybrid active filter, and the centralized control unit outputs pulse width modulation The signal and the trigger pulse signal respectively trigger the APF transistor and the thyristors in the thyristor-controlled reactor bank. The specific connection of the A-T hybrid reactive power compensation unit is: the thyristor control reactor group is connected to the compensation access point between the passive filter group and the main line of the power grid, and the output terminal of the active power filter is connected to the into the input terminal of the passive filter bank, and the output terminal of the passive filter bank is connected to the grid, thereby suppressing the harmonics of the grid; the thyristor-controlled reactor bank is composed of three sets of thyristor-controlled reactors connected in parallel, and each set of thyristor-controlled reactors The control reactor is composed of two thyristors connected in parallel and a reactor in series; the passive filter bank includes three sets of LC parallel branches, each branch is composed of three separate LC series branches connected in parallel. The overall structure of the reactive power compensation device for distributed power generation is shown in Figure 1, and the structure of the A-T hybrid reactive power compensation unit is shown in Figure 2.

As shown in Fig. 3, Fig. 3 is an overall structural diagram of the centralized control unit in the present invention. The centralized control unit includes sampling module, DSP control module, phase-locked loop circuit module, pulse generation module, information feedback and display module. The specific connection of the centralized control unit is: the voltage and current signals collected from the grid are connected to the input of the sampling module, the output of the sampling module is connected to the input of the DSP control module, and the output of the DSP control module is connected to the phase-locked loop circuit module. The input terminal, the output terminal of the phase-locked loop circuit module is connected to the input terminal of the pulse generation module, the output terminal of the pulse generation module is connected to the input terminal of the thyristor-controlled reactor group and the active power filter, the thyristor-controlled reactor group and the active power filter The output end of the filter is connected to the input end of the feedback module, the output end of the feedback module is connected to the input end of the display module, and the output end of the display module is connected to the input end of the DSP control module through the dual-port RAM communication module.

In this embodiment, the transformer adopts precision voltage transformer TR1102-1C and precision current transformer TR1102-2C. On the premise of satisfying sampling accuracy and real-time performance, in order to make full use of chip resources, this system adopts 16-way A/D converter integrated in DSP, the voltage range it can convert is 0.3V, and the voltage signal output by the transformer It is -5V+5V. The AC signal conditioning circuit is composed of a three-stage high-performance operational amplifier TL048. This circuit can convert the bipolar -5V+5V sinusoidal voltage signal into a unipolar AC voltage signal within 0.3V. The signal conditioning circuit is shown in Figure 4 . The voltage transformer and current transformer are connected to the input interface chip of the sampling module, and the voltage and current output terminals ACVA, ACVB, ACVC, ACCA, ACCB, ACCC of the sampling module are connected to the ADC input pins 2, 3, 4, 174, 173 and 172.

The sampling module described in the present invention includes a precision series voltage transformer, a current transformer and a DSP sampling module, and the DSP sampling module includes a signal conditioning circuit and a zero-crossing detection circuit; the high voltage side of the voltage transformer and the current transformer is connected to the power grid, The low-voltage side is connected to the input end of the DSP sampling module, the output end of the signal conditioning circuit is connected to the input end of the zero-crossing detection circuit, and the output end of the zero-crossing detection circuit is connected to the DSP control module as the output end of the sampling module; the DSP control module is mainly composed of TMS320F2812 It consists of a series of DSPs, and the output end of the DSP control module is connected to the input end of the pulse generation module. The specific connection of the sampling module is: the high-voltage side of the primary voltage-current transformer is connected to the grid, the low-voltage side is connected to the input end of the secondary voltage-current transformer, and the output end of the secondary voltage-current transformer is connected to the A/D conversion chip. The input end, the output end of the A/D conversion chip is connected to the input end of the DSP sampling board, the output end of the DSP sampling board is connected to the latch, and the DSP sampling board exchanges data with the single-chip 80C196 through the dual-port RAM.

The function of the sampling module is to collect the three-phase voltage and current of the power grid in real time, perform analog-to-digital conversion on the collected data, calculate the trigger angle of the thyristor, and store the results in real time.

The DSP control module adopts TMS320F2812 series DSP controller. This series of processors integrates a variety of peripherals, adopts high-performance static CMOS technology, has fast operation speed, and the working clock frequency reaches 150MH. It is a high-performance 32-bit CPU and adopts Harvard structure. , with fast mid-end response processing capability. The present invention uses DSPTMS320F2812 as the main control chip, which together with the peripheral units constitutes the operation main control board, and its structural block diagram is shown in Fig. 5 .

The phase-locked loop circuit module described in the present invention includes a zero-crossing detection circuit, a phase-locked loop circuit, a frequency multiplication circuit, a low-pass filter and a voltage-controlled oscillator. The zero-crossing detection circuit is mainly to convert the sinusoidal voltage signal to make it an applicable square wave signal, and to provide signals to the phase-locked frequency multiplication circuit. The connection relationship is: the output end of the zero-crossing detection circuit is connected to the input end of the phase-locked loop circuit, the output end of the phase-locked loop circuit is connected to the input end of the frequency multiplication circuit, and the frequency multiplication circuit generates sampling narrow pulses to trigger the sample-and-hold circuit to realize the locking Synchronized sampling.

The specific connection of the phase-locked loop circuit module is: the voltage and current signal is connected to the input end of the zero-crossing detection circuit, the output end of the zero-crossing detection circuit is connected to the input end of the phase comparator, and the output end of the phase comparator is connected to the low-pass filter The input end of the low-pass filter is connected to the input end of the voltage-controlled oscillator, and the output end of the voltage-controlled oscillator is connected to a shaping circuit for shaping the input signal.

The function of the phase-locked loop circuit module is: to generate a signal that is strictly synchronized with the sampling signal to directly control the sampling and conversion of the signal, to ensure that the ratio of the sampling frequency to the fundamental frequency of the signal is a fixed value, and to realize the balance between the sampling frequency and the fundamental frequency of the signal. Accurate tracking.

The complete phase-locking circuit structure is shown in Figure 6. The input signal becomes a periodic square wave signal through the zero-crossing detection circuit, and then after phase comparison, low-pass filtering and other important links, a sampling narrow pulse is generated to achieve phase-locking synchronization Sampling, the output is a 64-fold frequency pulse signal that is strictly synchronized with the input, and this signal is used as an external trigger signal that triggers A/D conversion. , the phase-locked frequency multiplication circuit structure adopts the CMOS integrated phase-locked loop chip CD4046 and the frequency divider CD4040 to achieve the purpose of 128 times accurate frequency multiplication. The connection circuit is shown in Figure 7. The input square wave signal PLLA is processed by frequency multiplication Become a square wave signal PLLB, which is used to trigger AD sampling. 74VHC4046MTC chip's VCO input pin 9 is connected to its own pin 13, the chip's VCO output pin 4 is connected to CD4040BCSJ chip's 10th pin, and CD4040BCSJ chip's 2nd pin is connected to 74VHC4046MTC chip's 3rd pin. foot.

The formation process of the trigger pulse is mainly based on the detected relevant voltage and current signals sent by the DSP, outputting the pulse width modulation (PWM) signal and the trigger pulse signal, which are used to drive the insulated gate bipolar in the active power filter respectively. Thyristors (SCRs) in Inactive Transistors (IGBTs) and TCRs. Its functional block diagram is shown in Figure 8. The 100V AC voltage signal sent by the sampling module is limited by the input, and after being in-phase shaped, it becomes a 50Hz duty cycle of 50% synchronous square wave signal CLR+, which is counted by a 12-bit synchronous counter through synchronous control , compare the counter output value with the 12-bit binary value of the trigger control angle sent by the DSP. When the two values are equal, a pulse TP+ is output. After TP+ passes through the pulse opening and blocking control circuit and the pulse stretching circuit, a thyristor trigger pulse J+ is formed, and then converted into a pulsed electrical signal to trigger the thyristor and transistor. The trigger principle is the same as above after the AC voltage signal is reversed and shaped.

The pulse generating module described in the present invention includes a synchronous voltage signal limiting circuit, a synchronous shaping circuit, and a pulse generating circuit; the pulse generating circuit includes a pulse opening and blocking circuit, a pulse stretching circuit and a photoelectric conversion circuit; a synchronous voltage signal limiting circuit The front end is connected to the DSP control module, the output end is connected to the input end of the synchronous shaping circuit, the output end of the synchronous shaping circuit is connected to the input end of the pulse generation circuit, and the output pulse controls the thyristor to control the reactor group and the signal trigger of the active power filter.

The specific connection of the pulse generation module is: the output end of the synchronous voltage signal limiting circuit is connected to the input end of the synchronous shaping circuit, the output end of the synchronous shaping circuit is connected to the input end of the 12-bit synchronous counter, and the output end of the 12-bit synchronous counter is connected to the 12-bit synchronous counter. The input end of the comparator, the output end of the 12-bit comparator are connected to the input end of the pulse opening and blocking circuit, the output end of the pulse opening and blocking circuit is connected to the input end of the pulse stretching circuit, the output end of the pulse stretching circuit is connected to the input end of the photoelectric conversion circuit, and the output of the photoelectric conversion circuit terminal control thyristor.

The function of the pulse generation module is to provide a trigger pulse signal with a sufficiently large amplitude and a certain leading edge steepness to the gate level of the thyristor, so as to ensure the safe and reliable operation of the thyristor valve group.

In this embodiment, the pulse generating module mainly includes a synchronization signal forming circuit, a trigger pulse generating circuit and a trigger pulse stretching circuit. The function of the synchronous signal forming circuit is to ensure that the thyristor and transistor can be triggered accurately. The control angle of the thyristor calculated in the control is based on the moment when the line voltage crosses zero and the voltage change rate is positive. And the time when the voltage change rate is negative is the 180° point. According to this method, the thyristor triggers the synchronous signal forming circuit in the pulse forming circuit. The circuit principle is shown in Figure 9. After the voltage signal is converted and processed, a square wave signal square+ synchronous with the line voltage is formed by the LM311P voltage comparator. After the shaping of the non-gate, it is used as the clearing signal CLR+ of the 12-bit synchronous counter. The working sequence is: when CLR+ is low level, the counter is cleared, and when CLR+ is high level, the counter starts counting, so that the counter counts synchronously with the line voltage. The synchronous counter is clocked at 1000000Hz. In this way, the counter counts up to 10000 in every half cycle (10ms). Obviously, the output value of the counter increases synchronously with time.

In the trigger pulse generation circuit, when the output value of the 12-bit synchronous counter is equal to the binary value of the thyristor control angle output by the DSP, a narrow pulse TP+ is output by the 12-bit digital comparison circuit. TP+ is sent to the pulse stretching circuit through the pulse opening and blocking circuit. The trigger pulse generation circuit is shown in Figure 10. In the figure, D0-D11 are the binary values transmitted by the 12-bit counter, Phase0-Phase11 are the binary values of the thyristor control angle output by the DSP, and Phase0-Phase3 are connected to the analog input pins of the SN74LS85N chip 10, 12, 13 and 15, Phase4-Phase11 are connected to pins 2, 4, 6, 8, 11, 13, 15 and 17 of the chip SN74LS688. U11 and U12 form a 12-bit value comparator, and TP+ is a trigger pulse.

The output of the trigger pulse generating circuit is a narrow pulse, which is not enough to trigger the thyristor and transistor, so a pulse stretching circuit is needed for stretching. The present invention uses the NE555P monostable circuit to widen the TP+ pulse. The widening circuit is shown in Figure 11. The narrow pulse is widened into a 1ms wide pulse through the 555 monostable circuit, and then used to trigger the thyristor.

The high-potential coupling energy harvesting circuit is mainly used as the working power supply when the thyristor is triggered. Considering that if the power is supplied from the control system, the power supply is easily disturbed, so the present invention adopts the method of directly harvesting energy from the high potential.

The main function of the power module is to provide various types of voltages required by the entire system. The present invention mainly includes +3.3V, +1.8V, +5V, ±12V devices, and the schematic diagram of the power module is shown in FIG. 12 . The input of the power module is AC 220V, and +24V DC power is obtained after passing through the AC/DC module, and then converted into +5V, ±15V DC power through the DC/DC module. The +5V power supply is converted into +3.3V and +1.8V power supplies by TI's power conversion chip TPS767D318 to provide working voltages for the DSP chip core and I/O ports respectively.

The information feedback and display module mainly includes an 80C196 single-chip microcomputer, a liquid crystal display module, an external main control human-machine interface module, that is, an external keyboard input and upper computer control part. The specific connection of the information feedback and display module is: the output end of the thyristor control reactor group and the active power filter is connected to the input end of the high potential board, the output end of the high potential board is connected to the input end of the return board, and the output end of the return board Connect the information display module; the information display module communicates with the DSP sampling module through the dual-port RAM.

In this embodiment, the control alarm signal is converted and encoded in the photoelectric conversion and encoding module, and then sent to 80C196 for processing. 80C196 controls the switching of FC through the relay, controls the keyboard and LCD module for manual control, and controls the communication of the upper computer for monitoring of the upper computer. 80C196 single-chip microcomputer and DSP carry on data communication through dual-port RAM.

The functions of the information feedback and display module are: the single-chip microcomputer assists the DSP to complete the interface processing, input the control parameters through the keyboard and store the control parameters in the dual-port RAM, the voltage, current and power factor read by the DSP are displayed on the LCD, and communicate with the host computer. communication.

According to the overall design of the present invention, what the single-chip microcomputer mainly completes is the collection of voltage and current signals in the circuit system, the display of the keyboard and liquid crystal, the input of various digital quantities, and the communication between the single-chip microcomputer and the DSP and the upper computer. The single-chip microcomputer system in the present invention mainly collects the three-phase voltage and current signals in the system and the three-phase current signals in the TCR for display by the host computer, and receives the return signal from the DSP for alarming and tripping. The DSP of the main control system and the display single-chip computer adopt the dual-port RAM communication mode, and the CY7C133 chip is selected. This chip is a high-speed 2Kb×16 CMOS dual-port SRAM, and has two independent and completely symmetrical address buses, data buses and control buses. It adopts 68-pin PLCC package, and the maximum access time is 25/35/55ns. The connection between CY7C133 and 80C196KC is shown in Figure 13. U10 in the figure is the right port where CY7C133 is connected to the single-chip microcomputer. The chip of CY7C133 is placed on the DSP data processing board, and the single-chip main board and the DSP data processing board are connected through a 34-pin flat cable. connect them. DPRAMCE is the strobe signal for dual-port RAM after decoding by CPLD, and it is active at low level. Utilize the read signal RD of the one-chip computer to complete the connection between the read and write arbitration logic busy signal DPRBUSY of the dual-port RAM and the P1.2 port of 80C196KC. Before writing data to the dual-port RAM, by detecting the level of the busy signal DPRBUSY, you can avoid writing at the same time or writing the same address unit when the DSP reads, thereby avoiding errors. Pins 2, 4, 6, 8, 10, 12, 14, and 16 of CY7C133 are connected to pins 17, 15, 13, and 11 of U1 SN74LS245N chip and pins 17, 15, 13, and 11 of U5 SN74LS245N chip , 1, 3, 5, 7, 9, 11, 13, 15 pins of CY7C133 and 18, 16, 14, 12 pins of U1 SN74LS245N chip and 18, 16, 14, 12 of U5 SN74LS245N chip Pins 18 and 20 of the CY7C133 chip are connected to pins 40 and 61 of the MCU, pins 60, 59, 58, 57, 56, 55, 54, and 53 of the MCU are connected to the SN74LS245N chip U1 Pins 2, 3, 4, and 5 of U5 are connected to pins 6, 7, 8, and 9 of the SN74LS245N chip of U5, and pin 61 of the MCU is also connected to pin 32 of the CY7C133 chip to realize DSP and MCU Communication.

It shows that the single-chip microcomputer and the upper computer adopt serial port communication, and the connection schematic diagram is shown in Figure 14. 80C196KC has a built-in serial I/O port, which can be conveniently used to communicate with the upper computer. Since the serial port of a general PC is at the RS-232 level, but the 80C196KC is at the TTL level, communication level conversion is required. In the present invention, MAX232 is used. MAX232 is the most commonly used conversion chip from RS-232 level to TTL level. It has voltage multiplication and conversion circuits inside. As long as a single +5V power supply can realize TTL level and RS-232 level Flat conversion, very convenient to use.

The main control man-machine interface module uses a 4×5 matrix keyboard as the system input device, and uses CM320240-10 type LCD as the system output device. For the convenience of actual installation, the matrix keyboard adopts the form of a membrane keyboard, and the LCD is fixed on a metal panel with screws and the keyboard. The schematic diagram of the 4×5 matrix keyboard connection is shown in Figure 15. The digital input terminals 12, 13, 14, 15, 16, 17, 18 and 19 of the 82C79 interface chip are connected to pins 18, 17, 16, 15, 14, 13, 12 and 11 of the SN74LS245N chip, 82C79 interface Pins 32, 33, and 34 of the chip are connected to pins 1, 2, and 3 of the SN74LS138N chip for analog output; pin 5 of the output end of the MC74HC74AN trigger is connected to pin 3 of the 82C79 interface chip. The KCS of the SN74LS245N chip is a chip select signal given by the CPLD according to the address assigned by the 82C79, and the 74LS245 is strobed when the MCU scans the bottom layer of the keyboard. The data transmission direction control pin DIR of 74LS245 determines the data transmission direction according to the level of the pin when the chip selection signal is valid.

The liquid crystal display module of the present invention adopts CM320240-10, which is a dot-matrix liquid crystal display module of Chinese and English characters and drawing mode, and has a built-in 12Kb ROM font code, which can display letters such as Chinese fonts, numeral symbols, English, Japanese and European, and Built-in dual layer display memory. In the text mode, it can receive the standard Chinese text internal code and display Chinese directly, without entering the drawing mode to draw Chinese, which can save a lot of MCU time, thereby improving the processing efficiency of the liquid crystal display Chinese. The connection between LCD and 80C196KC is shown in Figure 16. The four control lines lcdrs, lcdwr, lcdrd and lcdcs1 of CM320240-10 are connected to four high-speed output ports (HSO0-HSO3) of MCU through bus latch 74LS245. Output port HSO to control it.

A control method for harmonic suppression of a distributed power generation reactive power compensation device with a harmonic suppression function, specifically as follows:

1. Step 1: The sampling module collects the instantaneous three-phase voltage u _a , u _b , u _c and the instantaneous three-phase current i _a , i _b , _ic of the distributed power generation system;

2. Step 2: Calculation of the control angle of the thyristor: First, the phase-locked technology is used to measure the three-phase alternating current (including voltage, current and frequency), and then the control angle of the thyristor is calculated according to the mathematical model of the three-phase compensation susceptance and the sampling value of voltage and current. Then output the thyristor control angle. In the subsequent feedback part, the photoelectric conversion circuit realizes the output of the thyristor trigger signal and the reception of the status return signal.

3. Step 3: Generating a trigger pulse: First, the system voltage performs zero-crossing detection, and the accumulator is set to reset on the rising edge, so that the rising edge pulse of the zero-crossing detection voltage can reset the accumulator, and when accumulated to the next rise, a Sawtooth wave, compare the trigger angle of the thyristor calculated by DSP with this sawtooth wave, when the trigger angle of the thyristor is greater than the accumulated value of the accumulator, a rising edge pulse is triggered until the accumulator is reset, so that a wide pulse is obtained; because The obtained pulse is too wide, so by comparing the obtained wide-frequency pulse with the secondary accumulator in the same way, a narrow pulse signal sufficient to trigger the thyristor can be obtained;

4. Step 4: Control the on-off of the thyristor of the reactive power compensator and the transistor of the active power filter, and perform reactive power compensation and harmonic suppression on the distributed power generation system.

The passive filter bank is composed of three groups of LC parallel branches, each branch is composed of three groups of LC branches in series, and each group of branches is connected in series with a filter capacitor, which is installed at the output contact of the active filter In this way, the harmonic voltage of the node can be reduced, the injection of harmonic current into the power system can be suppressed, and it can also provide sufficient overcapacity compensation for the entire system.

Wherein, the measurement steps of the three-phase alternating current described in step two are as follows:

Step 1: First let the grid voltage be

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ \underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ \underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\end{array}\right]$

In the formula, u _a , u _b , u _c are instantaneous values of three-phase voltage, E _1n represents positive sequence voltage effective value, E _2n represents negative sequence voltage effective value, ω is angular frequency, θ _2n is negative sequence initial phase angle;

Step 2: Transform the abc three-phase to α-β two-phase coordinates of the three-phase voltage in the above formula to obtain the following,

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 32</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; n\&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>\end{array}\right]$

u _α and u _β are the corresponding two-phase voltage values under the α-β coordinates, and c ₃₂ is the conversion matrix from abc three-phase to α-β two-phase;

Step 3: Obtain the following matrix from the above formula and matrix c _sc ,

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; sc</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ]</span>\\ <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{<span\; class="notranslate">\; \&infin;</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; ]</span>\end{array}\right]$

In the above formula

${\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; sc</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>\end{array}\right]$

sin(ωt+θ) and cos(ωt+θ) are signals generated by a standard sinusoidal power frequency signal generator, and θ is any initial phase angle.

Step 4: Extracting the DC component from the above formula, the following can be obtained

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>\end{array}\right]$

Then the transformed voltage is

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>{{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; sc</span>}}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&omega;t</span>}\\ <span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&omega;t</span>}\end{array}\right]$

u _sf , u _cf are the converted two-phase voltage values, E _s , E _c are the extracted DC components, and c _sc ^-1 is the inverse matrix of the conversion matrix;

Step 5: Calculate the p and q components from the transformed phase voltage u _sf , u _cf and current i _α , i _β , the calculation formula is as follows

$\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; p</span>}\\ \mathrm{<span\; class="notranslate">\; q</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}& {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}& <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]$

Step 6: Calculate the detection current: the p component is subjected to the RBF neural network algorithm to obtain the corresponding AC component, and the q component is processed by the inversion algorithm to obtain the corresponding negative DC component, and then converted to obtain the α-β two-phase detection current. The specific formula is as follows

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="u\; sf"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">u</figure-callout></span><figure-callout\; id="2"\; label="u\; sf"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}& {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; cf</span>}}& <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}\end{array}\right]\left[\begin{array}{c}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; p</span>}}\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; q</span>}\end{array}\right]$

is the AC component corresponding to the p component, the instantaneous reactive power detection current i _a , i _b , i _c can be obtained from i _α and i _β through the conversion matrix, and the specific formula is as follows

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}}\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}\\ <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& \frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& <span\; class="notranslate">\; -</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]$

Step 7: Calculate the firing angle α of the thyristor according to the detected current;

When the thyristor is in normal operation, the fundamental current in the system is:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}{{\mathrm{<span\; class="notranslate">\; \&pi;X</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}$

The subscript 1 of the fundamental wave current I represents the first harmonic, which is the fundamental wave; X _L is the reactance, X _L =ωL; U _m is the peak value of the voltage; from this, the trigger angle can be calculated.

The calculation steps of the thyristor control angle in step 2 are as follows:

Step 1: Calculate the compensated admittance as follows:

Any three-phase load can be transformed into a delta connection, and the load admittance of each phase is composed of a real part (conductance) and an imaginary part (susceptance). Let the three-phase unbalanced load be

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; jB</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}\\ {\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; jB</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}\\ {\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; jB</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}\end{array}\right.$

Y _l,ab , Y _l,bc , Y _l,ca are the three-phase load admittance, Y _l,ab represent the load admittance between phase a and b, Y _l,bc represent the load between phase b and c Admittance, Y _l,ca represents the load admittance between phase c and a; G _l,ab , G _l,bc , G _l,ca are the three-phase load conductance, G _l,ab is the load admittance between phase a and b G _{l, bc} is the conductance between phase b and c, G _{l, ca} is the conductance between phase c and a; B _{l, ab} is the susceptance between phase a and b, B _{l, bc} is the susceptance between phase b and c, B _l,ca is the susceptance between phase c and a;

According to the balancing principle proposed by C.P. Steinmetz, the balancing of the three-phase unbalanced load is realized through impedance adjustment, which is completed in two steps:

The first step is to perform power factor correction. A compensation susceptance equal to the negative value of the load susceptance is connected in parallel to each phase load, so that the load becomes purely resistive, that is, the compensation susceptance is

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}\end{array}\right.$

In this way, the three-phase power factor is 1, but since G _l,ab ≠G _l,bc ≠G _l,ca , the load after compensation is still a three-phase unbalanced load.

，同时在c、a相间接入电感性电纳B_r,ca=-G_l,ab/

。同理，G_l,bc和G_l,ca可以用相同的办法加以平衡。The second step is to balance the three-phase pure conductance. In order to balance G _l,ab , connect the capacitive susceptance B _r,bc =G _l,ab /

, and connect the inductive susceptance B _r,ca =-G _l,ab /

. Similarly, G _l,bc and G _l,ca can be balanced in the same way.

After the above two-step balancing process, the total compensation admittance of the three-phase ideal compensation network is

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="3"\; label="ab"\; filenames="130315142838.png,130315142842.png"\; state="\{\{state\}\}">ab</figure-callout></span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}\end{array}\right.$

Where: B _r,ab , B _r,bc , B _r,ca are the admittances that the SVC should compensate for.

When designing a compensator, it is inconvenient to use the above formula as the control basis, because the load admittance is actually difficult to measure directly, so it is necessary to derive a practical formula with voltage and current. The following uses the symmetrical component method to analyze the load compensation, and assumes that the positive sequence three-phase balanced voltage is:

${\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; ,</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; ,</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; a</span>}\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}$

in $a={\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">e</figure-callout>}}^j=-\frac{1}{2}+\mathrm{<figure-callout\; id="3"\; label="j"\; filenames="130315142838.png,130315142842.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{\sqrt{3}}{2},a^2=e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}/3}=-\frac{1}{2}-\mathrm{<figure-callout\; id="3"\; label="j"\; filenames="130315142838.png,130315142842.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{\sqrt{3}}{2}.$

Line voltage:

$\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span>\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}\end{array}\right.$

The current of each phase line can be obtained as:

$\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}\end{array}\right.$

According to the symmetrical component method, the symmetrical components of the line current are as follows:

$\left[\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}\left[\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; 1</span>}\\ \mathrm{<span\; class="notranslate">\; 1</span>}& \mathrm{<span\; class="notranslate">\; a</span>}& {\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ \mathrm{<span\; class="notranslate">\; 1</span>}& {\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}& \mathrm{<span\; class="notranslate">\; a</span>}\end{array}\right]\left[\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right]$

分别是零序，正序，负序系统的参考相量，由以上两式得到不对称三相负载的线电流对称分量：In the formula

They are the reference phasors of the zero-sequence, positive-sequence and negative-sequence systems respectively, and the line current symmetrical component of the asymmetrical three-phase load is obtained from the above two formulas:

$\left\{\begin{array}{c}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; )</span>\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; a</span>}{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; )</span>\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}\end{array}\right.$

The load after compensation will be balanced if the negative sequence component of its line current is zero, which requires

${\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}$

If the load power factor after compensation is 1, the imaginary part of the positive sequence line current needs to be zero, then

$\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; [</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}$

The compensation admittance of SVC represented by voltage and current can be solved from the above formulas:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Im</span>}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Im</span>}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; Re</span>}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Im</span>}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; Im</span>}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Im</span>}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Im</span>}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; Re</span>}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>\end{array}\right.$

By properly transforming the above formula, the compensation susceptance expressed by the instantaneous value of load current and voltage can be obtained:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\end{array}\right.$

Now utilize the following relationship:

$\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; [</span>{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}\underset{\mathrm{<span\; class="notranslate">\; T</span>}}{<span\; class="notranslate">\; \&Integral;</span>}\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; idt</span>}$

This expression is the average value of reactive power over a complete cycle.

according to $u_a(-\frac{\mathrm{\&pi;}}{2})=\frac{{\mathrm{<figure-callout\; id="3"\; label="u\; bc"\; filenames="130315142838.png,130315142842.png"\; state="\{\{state\}\}">u</figure-callout>}}_{\mathrm{bc}}}{\sqrt{3}},u_b(-\frac{\mathrm{\&pi;}}{2})=\frac{{\mathrm{<figure-callout\; id="3"\; label="u\; ca"\; filenames="130315142838.png,130315142842.png"\; state="\{\{state\}\}">u</figure-callout>}}_{\mathrm{ca}}}{\sqrt{3}},u_c(-\frac{\mathrm{\&pi;}}{2})=\frac{{\mathrm{<figure-callout\; id="3"\; label="u\; ab"\; filenames="130315142838.png,130315142842.png"\; state="\{\{state\}\}">u</figure-callout>}}_{\mathrm{ab}}}{\sqrt{3}},$ The following formula can be obtained,

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="V"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">V</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}\underset{\mathrm{<span\; class="notranslate">\; T</span>}}{<span\; class="notranslate">\; \&Integral;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="V"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">V</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}\underset{\mathrm{<span\; class="notranslate">\; T</span>}}{<span\; class="notranslate">\; \&Integral;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="V"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">V</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}\underset{\mathrm{<span\; class="notranslate">\; T</span>}}{<span\; class="notranslate">\; \&Integral;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}\end{array}\right.$

The above formula can be used as the basis of the compensator control system, because all the mathematical operations on the right can be completed by electronic circuits. Although the integral period or average period is taken as one week as in the above formula, the integral time constant does not need to be strictly equal to T. For some For use (such as electric arc furnaces), it may be much shorter. If a digital controller is used, the subsequent integral can be replaced by a summation expression, where N is the number of points used in an integration period, n is the current sampling time, and i is the i-th sampling time, so that it can be practical Compensation susceptance calculation formula,

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ab</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="V"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">V</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; bc</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="V"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">V</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ca</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="V"\; filenames="130315142831.png,130315142838.png"\; state="\{\{state\}\}">V</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ab</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; bc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\end{array}\right.$

Step 2: Calculate the thyristor control angle as follows:

The compensation susceptance calculated in step 1 has the following relationship with the thyristor conduction angle,

${\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}$

B _L (a) is the susceptance of the reactor controlled by the thyristor; X _L is the reactance of the phase-controlled reactor; a is the trigger delay angle of the thyristor; δ is the conduction angle of the thyristor. It can be seen from the calculation formula that when the trigger delay angle a=90°, the thyristor is fully turned on, and the equivalent susceptance is changed by controlling the phase-shift trigger pulse of the anti-parallel thyristor pair connected to the phase-controlled reactor. So as to achieve the purpose of outputting variable and continuous reactive power.

The overall optimization algorithm process of the passive filter bank in the A-T hybrid reactive power compensation unit described in the present invention is as follows:

Step 1: System parameter setting, mainly including system reactive power compensation amount, voltage value of passive filter bank and harmonic limit value, etc.; system reactive power compensation amount is Q _SVC =Q ₁ +Q ₂ +...+ Q _h , the voltage and current limit of system harmonics are I _h <I _H , U _h <U _H . Q ₁ , Q ₂ , Q _h are the reactive power output by each branch; I _h is the system harmonic current, I _H is the maximum value of the system harmonic current; U _h is the system harmonic voltage, U _H is the system harmonic voltage max.

Step 2: Determine the total value Q of reactive power compensation that the actual passive filter bank can provide, and allocate the reactive power compensation of each branch of the passive filter bank according to the ratio of each harmonic current to the total harmonic current Quantity Q _i ;

Step 3: Correct the distribution of reactive power according to the voltage and current harmonic distortion rate and the parallel resonance frequency of the passive filter bank;

,滤波器组内、外谐振频率约束为f_ii

[50h(1+δ_emn),50h(1+δ_emp)]，f_io

[50h(1+δ_emn),50h(1+δ_emp)]，式中U₁为基波电压有效值；h为谐波次数，H为滤波器组数，δ_emn为负最大等效频率偏差，δ_emp为正最大等效频率偏差。The total harmonic distortion rate of the power system is

, the inner and outer resonant frequencies of the filter bank are restricted to f _ii

[50h(1+δ _emn ),50h(1+δ _emp )], f _io

[50h(1+δ _emn ),50h(1+δ _emp )], where U ₁ is the effective value of the fundamental voltage; h is the harmonic order, H is the number of filter groups, and δ _emn is the negative maximum equivalent frequency Deviation, δ _emp is the positive maximum equivalent frequency deviation.

The present invention adopts a common method in engineering application, and allocates the reactive power compensation output of each branch filter according to the ratio of the tuning harmonic current to the total harmonic ΣI _h .

Under ideal conditions, the relationship between the amplitude of each harmonic component of the current and α can be obtained through Fourier analysis, as shown in the following formula

$I_h\left(\mathrm{\&alpha;}\right)=\frac{4u}{\mathrm{\&pi;}{x}_L}\&times;\frac{\sin \mathrm{\&alpha;}\cos \left(\mathrm{h\&alpha;}\right)-h\cos \mathrm{\&alpha;}\sin \left(\mathrm{h\&alpha;}\right)}{h(h^2-1)}$ h=2k+1k=2,3,4···

Where α is the firing angle of the TCR thyristor, and X _L is the equivalent impedance of the reactor.

Step 4: Circularly calculate the parameter values of each branch filter, and judge whether the filter satisfies the conditions of the voltage and current harmonic distortion rate and the internal and external parallel resonance frequency of the passive filter bank. If the conditions are met, then judge the passive filter bank Whether the reactive power output satisfies the reactive power compensation amount of the actual distributed power generation reactive power compensation device, if the condition is not satisfied, then re-correct the harmonic coefficient, return to the corrected reactive power distribution step, and the reactive power output of the passive filter bank satisfies After the reactive power compensation amount of the actual distributed power generation reactive power compensation device is obtained, the passive filter bank can be operated for reactive power output and harmonic suppression. The overall optimization algorithm flow of this step is shown in Figure 17.

Claims (10)

1. the distributing generating reactive power compensator that harmonic restraining function is arranged is characterized in that: comprise A-T mixing reactive power compensation unit, central control unit and power module; A-T mixing reactive power compensation unit comprises thyristor-controlled reactor group (TCR), Active Power Filter-APF (APF) and passive filter group; The thyristor-controlled reactor group inserts the compensation access point between passive filter group and the electrical network backbone, Active Power Filter-APF and the series connection of passive filter group constitute hybrid active filter, and central control unit output pulse width modulation signal and start pulse signal trigger the thyristor in APF transistor and the thyristor-controlled reactor group respectively.

2. a kind of distributing generating reactive power compensator that harmonic restraining function is arranged as claimed in claim 1, it is characterized in that: the concrete connection of described A-T mixing reactive power compensation unit is: the thyristor-controlled reactor group inserts the compensation access point between passive filter group and the electrical network backbone, the output of Active Power Filter-APF inserts the input of passive filter group through filter reactance, the output of passive filter group connects electrical network, suppresses thereby electrical network is carried out harmonic wave;

Described thyristor-controlled reactor group is made of three groups of thyristor-controlled reactor parallel connections, and every group of thyristor-controlled reactor is by being composed in series with a reactor after two thyristor parallel connections;

Described passive filter group comprises three groups of LC parallel branches, and each three independent LC series arm of route composes in parallel.

3. a kind of distributing generating reactive power compensator that harmonic restraining function is arranged as claimed in claim 1, it is characterized in that: described central control unit comprises sampling module, DSP control module, phase-locked loop circuit module, pulse generating module, feedback information and display module;

The concrete connection of central control unit is: the input that inserts sampling module from the voltage and current signal of electrical network collection, the output of sampling module connects the input of DSP control module, the output of DSP control module connects the input of phase-locked loop circuit module, the output of phase-locked loop circuit module connects the input of pulse generating module, the output of pulse generating module connects the input of thyristor-controlled reactor group and Active Power Filter-APF, the output of thyristor-controlled reactor group and Active Power Filter-APF is connected the input of feedback module, the output of feedback module connects the input of display module, and the output of display module is connected to DSP control module input by the dual port RAM communication module again.

4. a kind of distributing generating reactive power compensator that harmonic restraining function is arranged as claimed in claim 3, it is characterized in that: described sampling module comprises accurate series voltage instrument transformer, current transformer and DSP sampling module, and the DSP sampling module comprises signal conditioning circuit and zero cross detection circuit; Electrical network is inserted in the high-pressure side of voltage transformer summation current transformer, low-pressure side connects the input of DSP sampling module, the output of signal conditioning circuit connects the input of zero cross detection circuit, and the output of zero cross detection circuit is connected into the DSP control module as the output of sampling module;

The DSP control module mainly is made up of the TMS320F2812 series DSP, and the output of DSP control module is connected to the input of pulse generating module;

The concrete connection of described sampling module is: the high-pressure side of primary voltage current transformer connects electrical network, low-pressure side connects the input of secondary voltage current transformer, the output of secondary voltage current transformer inserts the input of A/D conversion chip, the output of A/D conversion chip inserts the input of DSP sampling plate, the output of DSP sampling plate is connected to latch, and the DSP sampling plate is by dual port RAM and single-chip microcomputer 80C196 swap data simultaneously.

5. a kind of distributing generating reactive power compensator that harmonic restraining function is arranged as claimed in claim 3, it is characterized in that: described phase-locked loop circuit module comprises zero cross detection circuit, phase-locked loop circuit and frequency multiplier circuit, low pass filter and voltage controlled oscillator; The output of zero cross detection circuit connects the input of phase-locked loop circuit, and the output of phase-locked loop circuit connects the input of frequency multiplier circuit, and frequency multiplier circuit produces the sampling burst pulse and triggers sampling hold circuit, realizes phase-locked synchronized sampling;

The concrete connection of described phase-locked loop circuit module is: voltage and current signal inserts the input of zero cross detection circuit, the output of zero cross detection circuit connects the input of phase comparator, the output of phase comparator connects the input of low pass filter, the output of low pass filter connects the input of voltage controlled oscillator, the output of voltage controlled oscillator connects shaping circuit, input signal is carried out shaping handle.

6. a kind of distributing generating reactive power compensator that harmonic restraining function is arranged as claimed in claim 3, it is characterized in that: described pulse generating module comprises synchronous voltage signal amplitude limiter circuit, synchronous shaping, pulse generation circuit; Described pulse generation circuit comprises that pulse opens lockout circuit, stretch circuit and photoelectric switching circuit; Wherein synchronous voltage signal amplitude limiter circuit front end connects the DSP control module, output connects the input of synchronous shaping, the output of synchronous shaping connects the input of pulse generation circuit, the pulse control thyristor-controlled reactor group of output and the signal triggering of Active Power Filter-APF;

The concrete connection of pulse generating module is: the synchronous voltage signal limit circuit output end connects the input of synchronous shaping, the output of synchronous shaping connects the input of 12 bit synchronization counters, the output of 12 bit synchronization counters connects the input of 12 bit comparators, the output of 12 bit comparators connects pulse and opens the lockout circuit input, pulse is opened the lockout circuit output and is connected the stretch circuit input, the stretch circuit output connects the photoelectric switching circuit input, photoelectric switching circuit output control thyristor.

7. a kind of distributing generating reactive power compensator that harmonic restraining function is arranged as claimed in claim 3, its feature exists: described feedback information and display module comprise the high potential energy collecting circuit, repayment plate and information display module, information display module mainly comprises the 80C196 single-chip microcomputer, LCD MODULE, external master control human-machine interface module and PC control;

The concrete connection of feedback information and display module is: the output of thyristor-controlled reactor group and Active Power Filter-APF is connected the input of high potential plate, the output of high potential plate connects the input of repayment plate, the output link information display module of repayment plate; Information display module is by intercoming mutually between dual port RAM and the DSP sampling module.

8. one kind has the distributing generating reactive power compensator of harmonic restraining function to carry out the control method that harmonic wave suppresses, and it is characterized in that: specifically carry out as follows:

Step 1: sampling module is gathered the three-phase voltage instantaneous value u of distributing electricity generation system _a, u _b, u _c, three-phase current instantaneous value i _a, i _b, i _c

Step 2: the calculating of thyristor pilot angle: at first adopt Phase Lock Technique to carry out the detection of the three-phase alternating current signal of telecommunication, comprise voltage, electric current and frequency; Carry out the computing of thyristor pilot angle according to the Mathematical Modeling of three-phase compensation susceptance and electric current and voltage sampled value then, export the thyristor pilot angle again, in the part of feedback afterwards, photoelectric switching circuit is realized the output of thyristor triggering signal and the reception of state reporting signal;

Step 3: generate trigger impulse: at first system voltage carries out zero passage detection, accumulator is set to rising edge and resets, the voltage rising edge pulse of zero passage detection then can be that accumulator resets like this, be added to and form a sawtooth waveforms next time when rising, with thyristor trigger angle that DSP calculated therewith sawtooth waveforms compare, reset up to accumulator when the trigger angle of thyristor triggers a rising edge pulse during greater than the accumulated value of accumulator, so just obtain a wide cut pulse; Because the pulse that obtains is wide, so adopt in the same way resultant wideband pulse and secondary accumulator is compared, and then can obtain a narrow pulse signal that is enough to trigger thyristor;

Step 4: control reactive-load compensator thyristor and the transistorized break-make of Active Power Filter-APF, the distributing electricity generation system is carried out reactive power compensation and harmonic wave inhibition.

Described passive filter group is made up of three groups of LC parallel branches, and LC branch roads of three groups of series connection of each route compose in parallel, and every group of branch road filter capacitor of connecting again is installed in the output contact place of active filter.

9. a kind of distributing generating reactive power compensator that harmonic restraining function arranged according to claim 8 carries out the control method that harmonic wave suppresses, and it is characterized in that: the detection of described three-phase alternating current, specifically carry out as follows:

Step 1: at first make line voltage be:

$\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]=\left[\begin{array}{c}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sqrt{2}{E}_{1n}\sin \left(\mathrm{n\&omega;t}\right)+\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sqrt{2}{E}_{2n}\sin (\mathrm{n\&omega;t}+{\mathrm{\&theta;}}_{2n})\\ \underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sqrt{2}{E}_{1n}\sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})+\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sqrt{2}{E}_{2n}\sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3}+{\mathrm{\&theta;}}_{2n})\\ \underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sqrt{2}{E}_{1n}\sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})+\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sqrt{2}{E}_{2n}\sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3}+{\mathrm{\&theta;}}_{2n})\end{array}\right]$

U in the formula _a, u _b, u _cBe three-phase voltage instantaneous value, E _1nRepresent the positive sequence voltage effective value, E _2nRepresent the negative sequence voltage effective value, ω is an angular frequency, θ _2nBe the negative phase-sequence initial phase angle;

Step 2: three-phase voltage in the following formula is carried out the abc three-phase can get as follows to the transformation of coordinates of alpha-beta two-phase:

$\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}}\\ u_{\mathrm{\&beta;}}\end{array}\right]=c_{32}\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]=\left[\begin{array}{c}\sqrt{3}{E}_{1n}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sin \left(\mathrm{n\&omega;t}\right)+\sqrt{3}{E}_{2n}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sin (\mathrm{n\&omega;t}+{\mathrm{\&theta;}}_{2n})\\ -\sqrt{3}{E}_{1n}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\cos \left(\mathrm{n\&omega;t}\right)+\sqrt{3}{E}_{2n}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\cos (\mathrm{n\&omega;t}+{\mathrm{\&theta;}}_{2n})\end{array}\right]$

u _αAnd u _βBe two corresponding down phase voltage value of alpha-beta coordinate, c ₃₂Be transition matrix from the abc three-phase to the alpha-beta two-phase;

Step 3: by following formula and matrix c _ScObtain following matrix:

$\left[\begin{array}{c}{u}_s\\ u_c\end{array}\right]=c_{\mathrm{sc}}\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}}\\ u_{\mathrm{\&beta;}}\end{array}\right]=\left[\begin{array}{c}\sqrt{3}{E}_{1n}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\cos [(n-1)\mathrm{\&omega;t}-\mathrm{\&theta;}]-\sqrt{3}{E}_{2n}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\cos [(n+1)\mathrm{\&omega;t}+{\mathrm{\&theta;}}_{2n}-\mathrm{\&theta;}]\\ -\sqrt{3}{E}_{1n}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\sin [(n-1)\mathrm{\&omega;t}-\mathrm{\&theta;}]-\sqrt{3}{E}_{2n}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\cos [(n+1)\mathrm{\&omega;t}+{\mathrm{\&theta;}}_{2n}-\mathrm{\&theta;}]\end{array}\right]$

In the following formula:

$c_{\mathrm{sc}}=\left[\begin{array}{cc}\sin (\mathrm{\&omega;t}+\mathrm{\&theta;})& -\cos (\mathrm{\&omega;t}+\mathrm{\&theta;})\\ -\cos (\mathrm{\&omega;t}+\mathrm{\&theta;})& -\sin (\mathrm{\&omega;t}+\mathrm{\&theta;})\end{array}\right]$

Sin (ω t+ θ) and cos (ω t+ θ) are the signals that is produced by standard sine power frequency component generator, and θ is any initial phase angle;

Step 4: from following formula, extract DC component, can obtain following:

$\left[\begin{array}{c}{E}_s\\ E_c\end{array}\right]=\left[\begin{array}{c}\sqrt{3}{E}_{11}\cos (-\mathrm{\&theta;})\\ -\sqrt{3}{E}_{11}\sin (-\mathrm{\&theta;})\end{array}\right]$

Then the voltage after the conversion is:

$\left[\begin{array}{c}{u}_{\mathrm{sf}}\\ u_{\mathrm{cf}}\end{array}\right]={c_{\mathrm{sc}}}^{-1}\left[\begin{array}{c}{E}_s\\ E_c\end{array}\right]=\left[\begin{array}{c}\sqrt{3}{E}_{11}\sin \mathrm{\&omega;t}\\ -\sqrt{3}{E}_{11}\cos \mathrm{\&omega;t}\end{array}\right]$

E _s, E _cBe the DC component of extracting, c _Sc ^-1Be the inverse matrix of transition matrix, u _Sf, u _CfBe two phase voltage value after the conversion;

Step 5: by phase voltage u after the conversion _Sf, u _CfAnd current i _α, i _βCalculate p, the q component, computing formula is as follows:

$\left[\begin{array}{c}p\\ q\end{array}\right]=\left[\begin{array}{cc}{u}_{\mathrm{sf}}& u_{\mathrm{cf}}\\ u_{\mathrm{cf}}& -u_{\mathrm{sf}}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]$

Step 6: calculate and detect electric current: obtain corresponding alternating current component behind the p component process neural net filtering algorithm, the q component detects electric current through being converted to the alpha-beta two-phase again through obtaining negative accordingly DC component after the anti-phase algorithm process, and specifically formula is as follows:

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=\frac{1}{{u_{\mathrm{sf}}}^2+{u_{\mathrm{cf}}}^2}\left[\begin{array}{cc}{u}_{\mathrm{sf}}& u_{\mathrm{cf}}\\ u_{\mathrm{cf}}& -u_{\mathrm{sf}}\end{array}\right]\left[\begin{array}{c}-\tilde{p}\\ -q\end{array}\right]$

For the alternating current component of p component correspondence, by i _αAnd i _βCan obtain instantaneous reactive through transition matrix and detect current i _a, i _b, i _c, concrete formula is as follows:

$\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -\frac{1}{2}& \frac{\sqrt{3}}{2}\\ -\frac{1}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]$

Step 7: the trigger angle α that calculates thyristor according to the detection electric current;

When thyristor normally moved, fundamental current was in the system:

$I_1=\sqrt{2}\frac{(\mathrm{\&pi;}-\mathrm{\&alpha;})+\sin \mathrm{\&alpha;}\cos \mathrm{\&alpha;}}{{\mathrm{\&pi;X}}_L}{U}_m$

The subscript 1 expression first harmonic of fundamental current I is first-harmonic; X _LBe reactance, X _L=ω L; U _mIt is voltage peak; Promptly can be regarded as thus trigger angle.

10. a kind of distributing generating reactive power compensator that harmonic restraining function arranged according to claim 8 carries out the control method that harmonic wave suppresses, and it is characterized in that: the global optimization algorithm flow of described passive filter group is as follows:

Step 1: system parameters is set, and mainly comprises system's reactive power compensation amount, the magnitude of voltage of passive filter group and harmonic wave limit value etc.; System's reactive power compensation amount is Q _SVC=Q ₁+ Q ₂+ ...+Q _h, the voltage and current of system harmonics is restricted to I _h＜I _H, U _h＜U _H, I _HAnd U _HElectric current and voltage KB limit for system harmonics; Q ₁, Q ₂, Q _hReactive power for each branch road output; I _hBe system harmonics electric current, U _hBe system harmonics voltage;

Step 2: determine the total value Q of the reactive power compensation amount that actual passive filter group can provide, account for the ratio of total harmonic current, distribute the reactive power compensation amount Q of each branch road of passive filter group by the each harmonic electric current _i

Step 3: press electric current and voltage percent harmonic distortion and passive filter group parallel resonance frequency condition, revise the distribution of idle amount;

The total percent harmonic distortion of electric power system is

The inside and outside resonance frequency of bank of filters is constrained to f _Ii

[50h (1+ δ _Emn), 50h (1+ δ _Emp)], f _Io

[50h (1+ δ _Emn), 50h (1+ δ _Emp)]; U in the formula ₁Be the fundamental voltage effective value; H is a harmonic number, and H is the bank of filters number, δ _EmnBe negative maximum equivalent frequency departure, δ _EmpBe positive maximum equivalent frequency departure;

Step 4: the parameter value of each branch filter of cycle calculations, judge whether filter satisfies electric current and voltage percent harmonic distortion and the inside and outside parallel resonance frequency condition of passive filter group, if satisfy condition, judge again then whether the idle output of passive filter group satisfies the reactive power compensation amount of actual distributing generating reactive power compensator, just revise harmonic constant more again if do not satisfy condition, return and revise idle amount allocation step, the idle output of passive filter group is satisfied after the reactive power compensation amount of actual distributing generating reactive power compensator again, just can move that the passive filter group is carried out idle output and harmonic wave has suppressed.

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