CN106340900A - Distributed energy grid-connected and reactive power compensation compound control system - Google Patents

Abstract

The invention relates to a distributed energy grid connection and reactive power compensation composite control system, including a sampling module, a main control digital signal processor module, a PWM isolation drive module, an IGBT converter, a DC bus capacitor, and a filter circuit. The sampling module will The collected grid voltage signal, load current signal, IGBT converter output current signal, and DC bus capacitor voltage signal are converted into digital signal information and sent to the main control digital signal processor module. The main control digital signal processor module calculates Get the reactive current and grid-connected power of the system, and compare it with the set target value, then send the switch control command to the IGBT converter through the PWM isolation drive module, and the IGBT converter controls the output of the grid-connected current and compensation current of each phase . The invention enables the distributed energy access device to be more intelligently applied to the regional power grid by controlling the grid connection of each phase of the system and the output of the compensation current, and has the characteristics of high grid connection efficiency.

Description

Distributed energy grid-connected and reactive power compensation composite control system

technical field

The invention relates to a distributed energy grid-connected control system, in particular to a distributed energy grid-connected and reactive power compensation composite control system, which belongs to the field of grid-connected control of the power grid.

Background technique

With the continuous and high-speed development of the world economy, the demand for fossil energy in countries around the world is increasing, which leads to the rapid consumption of fossil energy. In addition, the large-scale development and utilization of fossil energy affect the global climate, and cause acid rain, greenhouse effects, ozone layer depletion and a series of environmental problems. Research and practice have shown that solar energy is inexhaustible, clean and harmless. It is the most reliable and effective green energy to solve the world's energy crisis and environmental pollution. It is predicted that photovoltaic power generation technology, which is the most important way to utilize solar energy resources, will develop rapidly in the next few decades, and the total photovoltaic power generation will account for more than 60% of the global power supply by the end of this century. Among them, the installation of photovoltaic grid-connected power generation systems accounts for more than 90% of all photovoltaic system installations, and it has undoubtedly become a development trend in the field of photovoltaic power generation. However, the photovoltaic power output is affected by weather changes with intermittent and uncertain characteristics, so that the utilization rate of photovoltaic grid-connected inverters is only about 20%, and frequent switching will also reduce the stability of the power grid. The power grid brings various disturbances and affects the power quality.

Under the situation of traditional energy shortage and environmental pollution becoming more and more serious, the research and development of new energy has received extensive attention at home and abroad. With its inexhaustible and inexhaustible advantages, solar energy has become one of the most promising new energy sources. At the same time, distributed power generation represented by new energy sources such as photovoltaic power generation is gradually developing from an independent system to a large-scale grid connection.

Since the 1970s, power electronics technology has developed rapidly, and the wide application of various electronic and electrical equipment has led to more and more phenomena such as harmonics, voltage fluctuations, flicker and three-phase unbalance in the power grid. These power quality problems seriously affect the safety, stability and economic operation of power supply equipment. In addition, with the vigorous development of distributed power generation technology of renewable energy, the grid connection of distributed new energy such as solar energy, wind energy, and fuel cells will lead to further instability of the grid. However, the precision equipment and household appliances used by users have higher and higher requirements on the power grid, and the serious power pollution and the demand for high-quality power quality are increasingly contradictory.

With the large-scale grid-connected application of various energy storage devices such as photovoltaic solar energy and wind energy, conventional distributed energy grid-connected power generation systems generally only provide active power to the grid, while the reactive power of the load is generally provided by the grid or by Special reactive power compensation equipment is provided. The current solar grid connection, wind energy grid connection, and electric vehicle V2G grid connection only send active power to the grid, but do not perform any control on the reactive power inside the regional grid or the power factor of the entire regional distribution network. The reactive power loss still exists and consumes the line capacity.

Photovoltaic power generation occupies an important position in the global new energy development and utilization, and its penetration rate to the power grid is gradually increasing. Under normal circumstances, the photovoltaic grid-connected power generation system only provides active power to the grid, that is, it converts the DC power of the solar photovoltaic array into AC power with the same frequency and phase as the grid and feeds it to the grid, and ensures that it has a high power factor. The reactive power of the load is generally provided by the grid or by dedicated reactive power compensation equipment. Although the dedicated reactive power compensation equipment has good compensation characteristics and effects, it will also increase additional construction costs.

As a kind of micro-grid power generation, the photovoltaic grid-connected system converts the direct current generated by the solar battery group into the alternating current that meets the requirements of the power grid through the grid-connected inverter, and then directly enters the public power grid. The introduction of a small amount of photovoltaic power generation modules will not have an impact on the grid, but large-scale application is very likely to damage the stability of the system and cause deterioration of power quality. Photovoltaic power generation is greatly affected by the environment. When the weather changes, the output power of the power generation system will change rapidly and drastically, with a maximum rate of change exceeding 10% of rated output per second. Changes in power generation will lead to large fluctuations in output voltage, and the same region will have a greater impact on power generation due to consistent environmental changes.

The traditional photovoltaic grid-connected power generation system includes photovoltaic arrays, grid-connected inverters and power grids. Among them, the photovoltaic array is a solar energy collection and conversion device, and its function is to absorb the light energy of solar radiation and convert it into direct current. The grid-connected inverter is the interface device of the entire photovoltaic grid-connected power generation system, and its function is to convert direct current into AC and connected to the grid. The photovoltaic power generation system can only provide active power to the grid, but cannot provide reactive power, and the active power is easily affected by the external environment such as sunlight irradiation and ambient temperature, and the power fluctuates greatly, which is an intermittent and unstable Energy will have an impact on the grid. The reactive power compensation system only provides reactive power compensation to the grid. Both have the following disadvantages: higher cost, single function, and low utilization rate.

The current grid-connected equipment works at full load or half-rated load for very little time, or even does not work for a considerable part of the time, but the equipment is designed according to the highest capacity, resulting in low efficiency of equipment use. In addition, for the access of distributed energy, there is no clear standard requirement for the active output and reactive output of the grid-connected equipment at the access point, resulting in the failure of the power quality in the region to reach a relatively optimized state.

In the case that there is no energy storage element installed on the DC side of the photovoltaic grid-connected power generation system, the system will stop supplying power when the light intensity is very low or there is no light at night. During this period, the photovoltaic grid-connected system must be disconnected from the grid and be in an idle state; only when When the light intensity reaches a certain level, it can be connected to the grid again. In the case of alternating day and night every day, the photovoltaic grid-connected system is repeatedly connected and disconnected from the grid, which has a great impact on the service life of the photovoltaic system and reduces the system utilization.

With the rapid growth of my country's economy, the capacity of the distribution network has increased sharply. The distribution lines below 10kV in various regions provide about 50% of the total power supply in the region. However, most of the distribution networks in my country have been operating at natural power factor for a long time the following. Insufficient reactive capacity and slow response are long-standing problems in my country's distribution network, which will cause huge losses every year. Reactive power compensation is very important to the safe and economical operation of distribution network. The distribution network is directly connected to the load, and the reactive power consumed by the distribution network line and the load must be balanced, otherwise the voltage operation level will be affected.

Contents of the invention

The distributed energy grid connection and reactive power compensation composite control system of the present invention discloses a new scheme, through real-time measurement of the system current situation, through the corresponding algorithm to analyze the size of the active and reactive components of the system, and through comparison with the set adjustment target value , to control the switch of IGBT, thereby controlling the output of grid-connected and compensation current of each phase of the system, and finally make the system output the maximum grid-connected power in the mode of active power priority, and compensate the reactive current of the system first in the mode of regional reactive power priority. The active and reactive power compensation of the system is provided in the regional balance mode, which solves the problems of high cost, single function and low utilization rate of the existing distributed grid-connected control system.

The distributed energy grid-connected and reactive power compensation composite control system of the present invention includes a sampling module, a main control digital signal processor module, a PWM isolation drive module, an IGBT converter, a DC bus capacitor, and a filter circuit. The DC bus capacitor is installed in the IGBT transformer The input terminal of the converter, the filter circuit is set at the output terminal of the IGBT converter, and the sampling module converts the collected grid voltage signal, load current signal, output current signal of the IGBT converter, and voltage signal of the DC bus capacitor into digital The signal information is sent to the main control digital signal processor module, and the main control digital signal processor module obtains the reactive current and grid-connected power of the system according to the received digital signal information. The result of comparing the grid power with the set adjustment target value sends a switch control command to the IGBT converter through the PWM isolation drive module, and the IGBT converter controls the output of the grid-connected current and compensation current of each phase according to the received switch control command. The control system outputs the maximum grid-connected power in the mode of active power output priority, the control system gives priority to compensating reactive current in the mode of regional reactive power output priority, and the control system outputs active power and reactive power compensation in the regional balanced output mode.

Further, the main control digital signal processor module of this solution includes a DSP chip and a CPLD chip. The DSP chip completes sampling signal processing, control calculation, and PWM signal output operations, and the CPLD chip completes the logic processing operation of digital signals.

Further, the sampling module of this solution includes a grid voltage detection module, a load current detection module, an IGBT converter output current detection module, a DC bus capacitor voltage detection module, and an AD sampling chip. The grid voltage detection module passes the grid voltage signal through the operational amplifier circuit After conditioning, it is sent to the AD sampling chip. The load current detection module sends the load current signal to the AD sampling chip after conditioning through the operational amplifier circuit. The IGBT converter output current detection module adjusts the output current signal of the IGBT converter through the operational amplifier circuit. Send it to the AD sampling chip, and the DC bus capacitor voltage detection module will send the DC bus capacitor voltage signal to the AD sampling chip after conditioning through the operational amplifier circuit, and the AD sampling chip will receive the grid voltage signal, load current signal, IGBT converter output The current signal and the DC bus capacitor voltage signal are converted into digital signal information and sent to the main control digital signal processor module.

Further, the main control digital signal processor module of this scheme performs calculation and processing according to the received digital signal information to generate a PWM signal. The PWM signal is processed by an external amplifier circuit and then processed by a PWM isolation drive module to form a PWM drive for driving an IGBT converter. Signal.

Further, the control system of this solution also includes a protection circuit, and the protection circuit sends a shutdown command to the PWM isolation drive module according to the collected signal that the voltage of the DC bus capacitor is too high.

Further, the control system of this solution also includes an IGBT converter temperature detection module, the IGBT converter temperature detection module includes an AD chip, and the IGBT converter temperature detection module passes through a two-wire system according to the collected high temperature signal of the IGBT converter The serial bus communication interface sends the high temperature alarm signal to the main control digital signal processor module, and the main control digital signal processor module closes the PWM isolation drive module through the protection circuit according to the received high temperature alarm signal.

Further, the control system of this program also includes communication modules RS485, RS232 and charged erasable programmable read-only memory. The main control digital signal processor module communicates with the control center through the communication modules RS485 and RS232. The main control digital signal processor module communicates through The charged erasable programmable read-only memory protects and stores data.

Further, the control system of this scheme also includes a phase-locked loop. The phase-locked loop includes a phase detector, a loop filter, and a voltage-controlled oscillator. The phase detector compares the phase information of the grid voltage with the phase of the output phase-locked signal The difference of the information is output to the loop filter, and the signal of the difference is filtered out by the loop filter and enters the voltage control oscillator to adjust the phase information until the output phase information is consistent with the phase information of the grid voltage.

The distributed energy grid connection and reactive power compensation composite control system of the present invention controls the output of each phase grid connection and compensation current of the system, so that the distributed energy access device can be more intelligently applied to the regional power grid, and has high grid connection efficiency. features.

Description of drawings

Figure 1 is a schematic diagram of the principle of the program control system.

Fig. 2 is a schematic diagram of the principle of the control circuit of the control system of this solution.

Fig. 3 is a schematic diagram of the principle of the control flow of the control system of this solution.

Figure 4 is a schematic diagram of the topological structure of a photovoltaic grid-connected inverter.

Fig. 5 is a schematic diagram of the topological structure of the reactive power compensation inverter.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

Photovoltaic grid-connected power generation systems generally include voltage and current sampling output by photovoltaic cell arrays, grid-connected inverter output current sampling, grid voltage sampling, power electronic converters and control systems, etc. The main circuit of the grid-connected inverter in the three-phase photovoltaic grid-connected power generation system generally adopts a voltage-type full-bridge structure, which is completely consistent with the main circuit of the conventional active reactive power compensation device. Therefore, the grid-connected and reactive power The compensation composite control device can effectively save equipment investment, simplify the system structure, and has excellent fast response characteristics of reactive power compensation, which plays an important role in improving the power supply capacity and quality of the power grid terminal. The key technology of the grid-connected and reactive power compensation compound control device is the detection of system current and algorithm design. In order to ensure the quality of power supply of the grid, the device must be able to achieve rapid response according to the system current. The grid-connected and reactive power compensation composite control device of this scheme mainly measures the system current in real time, analyzes the active and reactive components of the system through corresponding algorithms, and controls the IGBT switch by comparing with the set adjustment target value. In order to control the output of grid-connected and compensation current of each phase of the system, and finally make the system output the maximum grid-connected power in the mode of active power priority, first compensate the reactive current of the system in the mode of regional reactive power priority, and provide system power in the mode of regional balance active and reactive compensation.

As shown in Figure 4, a schematic diagram of the topological structure of a photovoltaic grid-connected inverter. This program adopts double-loop control mode. The outer loop controller is mainly used to reflect different control purposes, while generating the inner loop reference signal, and generally has a slow dynamic response. The inner-loop controller mainly performs fine adjustments to improve the power quality output by the inverter, and generally has a faster dynamic response. The grid-connected inverter uses the power loop as the outer loop to directly control the output power of the distributed power supply to ensure that the system can output constant power in the case of grid voltage fluctuations. With the current loop as the inner loop, combined with the voltage space vector modulation method, the defect of high sampling frequency caused by the unfixed traditional switching frequency is solved, and finally high power factor and constant power grid connection are realized. The grid-connected inverter is the core equipment of the photovoltaic grid-connected power generation system. This scheme uses a voltage-type inverter and connects a large capacitor in parallel on the DC side, which can better resist the DC voltage fluctuation caused by grid interference. It is suitable for grid voltage Occasions with large fluctuations. The grid-connected power generation system uses an inverter device to convert DC power into AC power and input it into the grid. This scheme adopts a non-schedulable photovoltaic grid-connected power generation system.

The reactive power required by the distribution network usually requires the installation of a reactive power compensation device in the distribution system to generate reactive power to compensate for the reactive power consumed by the distribution network. Reactive power compensation for distribution network is an important condition for the safe and economical operation of distribution network, and it is related to whether users can obtain safe and high-quality electric energy. Reactive power compensation in distribution network can effectively improve power quality, reduce line loss, improve line transmission efficiency, improve line transmission capacity, and effectively increase the output of generators and transformers. The reactive power compensation control system of this scheme is composed of two parts, the command current operation circuit and the compensation current generation circuit. The command current operation circuit detects the reactive current component in the compensation object current, and the compensation current generation circuit generates the actual compensation current according to the command signal of the compensation current obtained by the command current operation circuit. This program uses the detection method of instantaneous reactive power theory to detect reactive current. The basic idea of instantaneous reactive power theory is to transform the voltage and current of the abc three-phase system into vectors on the αβο coordinate system, define the dot product of voltage and current vectors as instantaneous active power, and define the cross product of voltage and current vectors as Instantaneous reactive power, and then invert these powers into three-phase compensation currents. The theory of instantaneous reactive power breaks through the definition of power based on the "average value" of traditional power theory, and makes real-time detection of reactive current possible. This method has good real-time performance for the transient current detection of the three-phase balanced system, is conducive to the rapid control of the system, and can obtain a good compensation effect.

As shown in Figure 5, the topological structure of the reactive power compensation inverter is basically the same as that of the photovoltaic grid-connected inverter. From the comparison and analysis of the system structure, function and control method, it is found that the two have many similarities: ⑴In terms of structure, SVG and photovoltaic grid-connected power generation systems are the same in terms of inverter topology and the way they are connected to the grid; It is grid-connected power generation, that is, injecting active electric energy into the grid, both of which are injected into the grid in the form of current; (3) control method, the AC side of both belongs to current tracking control, and the same current tracking control method can be used. For this type of system, a capacitor is usually connected to the DC side, and the capacitor voltage on the DC side is maintained by the energy exchange between the system itself and the grid. When the DC side voltage of the capacitor exceeds a given value, the capacitor injects active power into the grid to reduce the DC voltage. Side voltage, in order to maintain its stability. Therefore, if the compensation current generation function is set in the control process of the photovoltaic power generation system, the photovoltaic grid-connected system can realize reactive power compensation to the grid while injecting active power into the grid.

Grid-connected photovoltaic systems can inject active power or reactive power into the grid. When the photovoltaic system is connected to the grid with unit power factor control, if the grid-connected point voltage u changes by △u, the corresponding current i will change by △i. When the photovoltaic active power output is greater than a certain value, it will inevitably cause the grid-connected point voltage to exceed the limit. At this time, the photovoltaic power station should make full use of the reactive power adjustment capability of the inverter to regulate reactive power and voltage. The reactive power output capability of the inverter is not only limited by its own capacity and transmission lines, but also by the DC side voltage if the inverter capacity is large enough. With the increase of active power and reactive power output of the photovoltaic system, the output voltage of the inverter increases. The AC output voltage of the inverter exceeds its constraint range. At this time, the freewheeling diode connected in antiparallel with the IGBT is turned on, causing commutation failure, the DC side voltage of the inverter rises, the output current is distorted, and the active power and reactive power appear. Therefore, when the power grid needs the photovoltaic system to provide greater reactive power support, the active power output should be reduced.

In order to realize the optimal design of composite current, it is first required that the grid-connected active current and the system reactive current used for compensation can be controlled separately, that is, the current has diversity. For the optimally designed composite current, although each phase may contain an active component, the active component is not consumed on the inverter bridge, but transmitted to the grid through the inverter. To achieve system reactive power compensation and regional active power balance, it is necessary to know the reactive components and active components required by each phase load. Through the vector transformation of the symmetrical component method, the current components (including the imaginary part of the positive sequence current phasor and the negative sequence current phasor) other than the real part (ie active component) of the positive sequence current phasor can be obtained. As shown in Figure 3, the device detects the grid voltage and system current, and calculates the reactive power compensation current and load active current. Through the PI controller, according to the principle of deadbeat control, a fixed frequency PWM pulse is generated to drive the IGBT of the inverter power tube to be turned on and off. This control scheme can obtain a stable and rapid current control effect, and can also correspondingly improve the system power factor.

The current loop mainly includes the following parts: detection unit of grid-connected current and load reactive current, control unit and PWM pulse distribution unit. The control unit generates a modulation signal, which only changes at the sampling time and remains unchanged until the next sampling time. It is sent to the pulse distribution unit to generate the switching signal of the IGBT to realize the control function. The device adopts a phase-locked loop phase tracking system, which can ensure that the output phase and frequency signal are consistent with the input signal. Its working principle is that the phase detector outputs the difference between the phase information of the grid voltage and the phase information of the output phase-locked signal to the The loop filter filters out the noise in the difference signal, and then enters the voltage control vibrator to adjust the phase information and output it until the final output phase information is consistent with the phase information of the grid voltage to achieve phase locking.

As shown in Figure 1, the principle schematic diagram of the control system of this scheme. The main function of the control system of this scheme is to adjust the real-time monitoring signal, quickly calculate according to the preset algorithm, and finally output the control signal to the power circuit. In the experimental prototype, the main control digital signal processor selects the DSP core TMS320F28335 of TI Company, according to the set control mode, calculates the voltage and current signals of the DC and AC sides of the main circuit obtained by the sensor and conditioned by the analog circuit. Judgment and output to realize the preset strategy. The control system also needs CPLD to realize the logic combination of PWM signals, realize peripheral communication through RS485 and RS232, and realize data protection and storage by EEPROM. In Figure 1, the output terminals of the grid marked with U _a , U _b , and U _c are AC grid voltages, and the load is a three-phase nonlinear load that consumes reactive power. The composite control system is composed of two parts, namely the reactive current detection circuit and the compensation current generation circuit. The main circuit adopts a PWM converter composed of insulated gate bipolar transistors (IGBT), which mainly works as an inverter when generating compensation current. The basic working principle of the system is to detect the current in the load through the sampling detection circuit, obtain the reactive current and grid-connected power in the load through the calculation of the digital signal processor (DSP), and then control the active power through the working mode set by the control strategy and reactive power output. The hardware design of SVG mainly includes main circuit design and control circuit design. The control circuit is an important part of SVG. Figure 2 shows the structural block diagram of the hardware circuit of the SVG control system. It mainly consists of the following parts: DSP control circuit, Voltage and current detection circuit, PWM output circuit, protection circuit, IGBT temperature detection, etc.

⑴DSP control circuit

The entire control circuit uses TI's 32-bit floating-point microprocessor TMS320F28335 as the main control chip. TMS320F28335 is a member of Delfino MCU series products, and its operating frequency can be as high as 150MHZ. It is a highly integrated and high-performance solution for applications requiring strict control. The control system is supplemented by Altera's EPM570T100 CPLD chip. The CPLD mainly performs logic processing of some digital signals, while the DSP chip completes the main functions of sampling signal processing, control calculation, protection and PWM signal output.

⑵AD signal detection and conditioning unit

AD signal detection includes three-phase power grid voltage signal detection, three-phase load current signal detection, three-phase SVG output current detection, and two-way DC side capacitor voltage detection. AD7657 samples and converts, and outputs digital signals to DSP for processing. IGBT temperature detection is completed by a separate AD chip AD7995, which is output to DSP through a two-wire serial bus (I2C) communication interface.

⑶ Protection circuit

The function of the protection circuit is to protect the trouble-free operation of the SVG. When the voltage of the SVG DC capacitor is too high, or the voltage difference between the upper and lower capacitors is too large, the grid voltage is abnormal, and the temperature of the power device is too high, the protection circuit will generate a protection signal and cut off the PWM output signal. Turn off SVGs.

⑷PWM drive

The DSP generates a PWM signal after calculation and processing, the signal is amplified by an external amplifier circuit, and then a PWM drive signal with drive capability is formed through an isolation drive circuit to drive the IGBT of the main power circuit.

⑸Communication

The serial communication interface (SCI) and serial peripheral interface (SPI) communication interfaces of the DSP control system have all been reserved for future communication with the control center.

In reactive power compensation mode, the controller collects the required power from the power grid, converts it into a digital quantity through AD, calculates the power to be compensated, and then converts it into an IGBT bridge control signal, and the controller sends a high-speed switching PWM signal to control the IGBT bridge switch, so as to provide reactive power and harmonic power for the load, and the transformer no longer needs to provide the reactive power required by the load. In the grid-connected mode, the controller collects the grid voltage in real time, detects whether the grid working status is normal, and determines whether the output current of the inverter is synchronized with the grid voltage. network. The conversion between modes can be set on the LCD screen provided by the device according to the needs of the power grid. The device is connected to the power grid by parallel connection, and has three working modes: grid-connected priority, reactive power compensation priority, and regional power balance priority, and has RS485/RS232 communication interface for data transmission and viewing.

Unless otherwise specified, the electrical appliances, circuits, modules and electronic components involved in the above schemes can choose common designs and schemes in the field according to their specific functions, and can also choose other designs and schemes according to actual needs.

In the photovoltaic grid-connected power generation system, it is feasible in theory and practice to combine reactive power detection and compensation control with grid-connected power generation control to realize unified control of grid-connected power generation and reactive power compensation. The operation of its grid-connected power generation can not only effectively provide the active power of the grid, but also compensate the reactive current in the transmission grid, which is conducive to the further improvement of the power supply capacity and quality of the grid, especially for the power supply at the end of the grid. The reactive current detection method based on the instantaneous reactive power theory adopted by the system has been successfully realized in the experiment under the support of high-speed DSP digital control.

This program simulates photovoltaic grid-connected power generation by in-depth analysis of key technologies such as grid-connected inverter control, reactive power detection and compensation of photovoltaic grid-connected power generation systems, and comprehensively controls grid-connected power generation and reactive power compensation. The photovoltaic grid-connected system integrates the functions of grid-connected power generation control and reactive power compensation. In areas where the grid operation is relatively stable, the photovoltaic grid-connected power generation function is the main function, and the reactive power compensation function is supplemented. In some areas, the reactive power compensation function of the power grid is mainly realized, and the function of grid-connected power generation is supplemented. The research of this scheme is in line with the reality that my country's geographical conditions are greatly different, economic development is unbalanced, and energy requirements are different. It has broad application prospects and important practical significance for the development and utilization of new energy and the harmonious development of green power grids. By comparing the structure of the photovoltaic grid-connected power generation system and the reactive power compensation system, this program reveals that there are similarities in the structure of the two. The photovoltaic grid-connected power generation system provides active power to the grid through the converter, and the reactive power system provides reactive power compensation to the grid through the converter. Therefore, in the grid-connected power generation system, reactive power detection and compensation control and grid-connected power generation control In combination, it is necessary to realize the unified control of grid-connected power generation and reactive power compensation. The operation of grid-connected power generation can not only effectively provide grid active power, but also compensate the reactive current in the transmission grid, which is conducive to the further improvement of grid power supply capacity and quality.

With the world's thirst for new energy power generation and the "Twelfth Five-Year Plan", my country's strong support for photovoltaic and other renewable energy industries, the photovoltaic grid-connected power generation system of this plan can not only effectively realize photovoltaic power generation, improve power quality and Reducing power loss is also of great significance to saving corresponding equipment investment and improving system utilization.

The distributed energy grid-connected and reactive power compensation composite control system of this scheme is not limited to the content disclosed in the specific implementation. The technical schemes in the embodiments can exist independently or include each other. Those skilled in the art can combine Simple replacement schemes made by common knowledge also belong to the scope of this scheme.

Claims (8)

1. distributed energy is grid-connected and reactive-load compensation multiplex control system, it is characterized in that including sampling module, master control digital signal Processor module, pwm isolation drive module, igbt current transformer, dc-link capacitance, filter circuit, described dc-link capacitance It is located at the input of described igbt current transformer, described filter circuit is located at the outfan of described igbt current transformer, described sampling mould Block is by the mains voltage signal collecting, load current signal, the output current signal of described igbt current transformer, described direct current The voltage signal of bus capacitor is converted into digital signal information and sends described master control digital signal processor module, described master control to Digital signal processor module obtains the reactive current of system, grid-connected power according to the described digital signal information receiving, described Master control digital signal processor module is led to according to described reactive current, grid-connected power and the regulation desired value result of the comparison setting Cross described pwm isolation drive module and send switching control instruction to described igbt current transformer, described igbt current transformer is according to receiving Described switching control instruction control each phase grid-connected current, compensate the output of electric current, described control system is preferential in active output Pattern under export maximum grid-connected power, described control system preferential compensating reactive power electricity under the preferential pattern of the idle output in region Stream, described control system exports active, reactive-load compensation under regional balance output mode.

2. distributed energy according to claim 1 is grid-connected and reactive-load compensation multiplex control system is it is characterised in that described Master control digital signal processor module includes dsp chip, cpld chip, and described dsp chip completes sampled signal and processes, controls meter Calculate, pwm signal output operates, described cpld chip completes the logic processing operations of digital signal.

3. distributed energy according to claim 2 is grid-connected and reactive-load compensation multiplex control system is it is characterised in that described Sampling module includes network voltage detection module, load current detection module, igbt output current of converter detection module, direct current Bus capacitor voltage detection module, ad sampling A/D chip, described network voltage detection module is by mains voltage signal by amplifier electricity Described ad sampling A/D chip is sent to, load current signal is adjusted by described load current detection module by discharge circuit after the conditioning of road Described ad sampling A/D chip is sent to, igbt output current of converter is believed by described igbt output current of converter detection module after reason Described ad sampling A/D chip is sent to, described dc-link capacitance voltage detection module is female by direct current after number nursing one's health by discharge circuit Line capacitance voltage signal sends described ad sampling A/D chip by discharge circuit to after nursing one's health, described ad sampling A/D chip is by the electricity receiving Net voltage signal, load current signal, igbt output current of converter signal, dc-link capacitance voltage signal are converted into numeral Signal message sends described master control digital signal processor module to.

4. distributed energy according to claim 3 is grid-connected and reactive-load compensation multiplex control system is it is characterised in that described Master control digital signal processor module carries out calculation process according to the digital signal information receiving and produces pwm signal, described pwm letter Number through outside amplifying circuit process after after described pwm isolation drive resume module formed drive described igbt current transformer pwm Drive signal.

5. distributed energy according to claim 4 is grid-connected and reactive-load compensation multiplex control system is it is characterised in that described Control system also includes protection circuit, the letter of the overtension according to the described dc-link capacitance collecting for the described protection circuit Number to described pwm isolation drive module send out code.

6. distributed energy according to claim 5 is grid-connected and reactive-load compensation multiplex control system is it is characterised in that described Control system also includes igbt current transformer temperature detecting module, and described igbt current transformer temperature detecting module includes ad chip, institute The high temperature signal stating igbt current transformer temperature detecting module according to the described igbt current transformer collecting is total by twin wire serial High temperature alarm signal is sent to described master control digital signal processor module, described master control Digital Signal Processing by line communication interface Device module closes described pwm isolation drive module according to the high temperature alarm signal receiving by described protection circuit.

7. distributed energy according to claim 2 is grid-connected and reactive-load compensation multiplex control system is it is characterised in that described Control system also includes communication module rs485, rs232 and band EEPROM, described master control digital signal Processor module is communicated with control centre by communication module rs485, rs232, and described master control digital signal processor module is led to Cross band EEPROM data to be carried out protecting, stores.

8. distributed energy according to claim 1 is grid-connected and reactive-load compensation multiplex control system is it is characterised in that described Control system also includes phase-locked loop, and described phase-locked loop includes phase discriminator, loop filter, voltage-controlled oscillator, described The difference of the phase information of line voltage and the phase information of the lockin signal of output is exported described loop filtering by phase discriminator Device, the signal of described difference filters through described loop filter and enters described voltage-controlled oscillator adjustment phase place information after noise Until output phase information is consistent with the phase information of line voltage.