CN222395454U - A small capacity low voltage active filter device - Google Patents
A small capacity low voltage active filter device Download PDFInfo
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- CN222395454U CN222395454U CN202323633018.9U CN202323633018U CN222395454U CN 222395454 U CN222395454 U CN 222395454U CN 202323633018 U CN202323633018 U CN 202323633018U CN 222395454 U CN222395454 U CN 222395454U
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Abstract
The utility model discloses a low-capacity low-voltage active filtering device which is suitable for being installed on a low-voltage user side in a scattered way, a main circuit unit is in modularized design and is connected in parallel on a bus between an alternating current power supply and a nonlinear load, a main control mode and a multi-pair control mode are adopted, a main controller is a control core of the whole parallel device, an auxiliary controller only needs to execute commands of the main controller and does not need to carry out additional analysis and calculation, so that a plurality of main circuit units connected in parallel can be coordinated uniformly, the main controller can realize closed-loop control according to a real-time detection result of a current detection unit, continuously correct compensation currents output by the main circuit units, offset harmonic waves or reactive currents in load currents on the bus, enable current waveforms of the power supply side to be approximate to sine waves, eliminate influences of the harmonic waves and the reactive currents on other equipment and relay protection devices in a power grid, and the main circuit unit has good output consistency, flexible application and stable compensation effect.
Description
Technical Field
The utility model relates to the technical field of low-voltage power distribution, in particular to an active filter, and particularly relates to a low-capacity low-voltage active filter device.
Background
The adoption of an active filter (APF) is a main means of harmonic wave control at present, the active filter is a novel power electronic device for dynamically restraining harmonic waves and compensating reactive power, the active filter can compensate the harmonic waves and the reactive power which change in size and frequency, the active filter is usually compensated in a concentrated manner at an outlet of a power grid, the purchase and installation cost is high, the dispersed load type small users are influenced on harmonic wave control at the user side and energy conservation transformation enthusiasm, and the quality of a power grid is negatively influenced.
Aiming at the characteristic of small scattered load type users, the compensation capacity of a power unit of a low-voltage active filter is generally about 30A, different modules can be flexibly configured according to different low-voltage power supply equipment by adopting a modularized design, and when the current to be compensated of the system exceeds the rated compensation capacity of a single module, a mode of running a plurality of modules in parallel is generally selected.
The existing parallel connection mode of a plurality of modules is shown in fig. 1, N APFs are respectively connected to a bus between an alternating current power supply and a linear load, a secondary measurement circuit of a current transformer is connected into each APF in a serial connection mode, and each APF respectively outputs 1/N harmonic compensation current according to the measured load current harmonic wave, so that the sum of output currents reaches the required compensation current. In the parallel mode, the control mode is similar to that of a single operation, each APF operates independently, but if one APF fails and exits from operation, the other APFs still output compensation current in a 1/N mode, so that harmonic current cannot be normally compensated. In addition, the parallel connection mode can only calculate the compensation current by measuring the load current harmonic wave, but in many cases in an actual distribution system, the total network side current can only be measured by a current transformer of a distribution cabinet, and because the output current of each parallel APF has an influence on the network side current at the same time, the accurate compensation current is difficult to obtain, so that the application occasions of the parallel connection mode are greatly limited.
Disclosure of utility model
In order to solve the technical problems in the background technology, the utility model provides a low-capacity low-voltage active filter device, which adopts a main and multi-pair parallel architecture, can realize closed-loop control according to real-time detection results, and has good output consistency.
The aim of the utility model can be achieved by the following technical scheme:
a low-capacity low-voltage active filtering device comprising:
The main circuit unit is connected in parallel on a bus between the alternating current power supply and the nonlinear load to generate compensation current to offset harmonic or reactive current in load current on the bus;
the current detection unit is connected to the bus to detect harmonic waves or reactive currents of load current in real time;
and the main controller is connected with the current detection unit and the main circuit unit and used for controlling the main circuit unit to generate compensation current with the same magnitude and opposite polarity as the harmonic or reactive current in the load current according to the harmonic or reactive current of the load current.
Further, the main circuit units are arranged in a plurality of parallel, and the main controller calculates the total reference current to be compensated according to the harmonic wave or reactive current of the load current and decomposes the total reference current into a plurality of compensation current signals corresponding to the main circuit units so as to control the main circuit units to generate corresponding compensation currents.
Further, the system also comprises a plurality of auxiliary controllers which are in communication connection with the main controller through optical fibers, the main controller is in control connection with one main circuit unit, the plurality of auxiliary controllers are respectively in control connection with other main circuit units, the main controller collects running states uploaded by the auxiliary controllers at fixed time in real time and transmits compensation current signals corresponding to the main circuit units to the auxiliary controllers, and the auxiliary controllers control the main circuit units connected with the auxiliary controllers to generate corresponding compensation currents according to the compensation current signals transmitted by the main controller.
Further, the main controller or the auxiliary controller outputs PWM pulse signals according to the compensation current signals corresponding to the main circuit units to control the main circuit units to generate compensation currents.
Further, the main circuit unit includes:
An inverter connected to a bus between the ac power source and the nonlinear load to generate a compensation current to offset harmonics or reactive currents in the load current on the bus;
the intelligent power module is connected with the main controller or the auxiliary controller, and controls the on-off of a power switch device on the inverter through a PWM pulse signal sent by the main controller or the auxiliary controller so that the inverter generates compensation current with the same magnitude and opposite polarity as the harmonic or reactive current in the load current on the bus;
and the output filter is connected between the inverter and the bus to filter out higher harmonic waves generated by on-off of the power switch device in the compensation current generated by the inverter.
Further, the inverter is composed of a three-phase bridge inverter circuit.
Further, the output filter adopts LCRLL type output filter.
Further, the main controller and the auxiliary controller both adopt a DSP chip and a CPLD chip.
Further, the current detection unit comprises an alternating current transformer and a current signal detection conditioning circuit, the alternating current transformer is connected to the bus, the current signal detection conditioning circuit is connected with the main controller, and the current signal detected by the alternating current transformer is converted, amplified and sent to the main controller.
The utility model has the beneficial effects that the utility model discloses a low-capacity low-voltage active filter device which is suitable for being installed on a low-voltage user side in a scattered way, a main circuit unit adopts a modularized design and is connected in parallel on a bus between an alternating current power supply and a nonlinear load, a main control mode and a plurality of pairs of main control modes are adopted, a main controller is a control core of the whole parallel device, a subsidiary controller only needs to execute commands of the main controller and does not need to carry out additional analysis and calculation, so that a plurality of main circuit units connected in parallel can be coordinated uniformly, the main controller can realize closed-loop control according to the real-time detection result of a current detection unit, continuously correct the compensation current output by each main circuit unit, offset harmonic waves or reactive currents in load currents on the bus, enable the current waveform of the power supply side to be approximate to sine waves, eliminate the influence of the harmonic waves and the reactive currents on other equipment and relay protection devices in a power grid, and have good output consistency, flexible application and stable compensation effect.
Drawings
Figure 1 is a schematic diagram of a parallel use of multiple APFs.
FIG. 2 is a schematic diagram of the system of the present utility model.
Fig. 3 is a system schematic diagram of a main circuit module according to the present utility model.
Fig. 4 is a single-phase equivalent circuit diagram of the output filter of the present utility model.
Fig. 5 is a circuit diagram of the current signal detection conditioning circuit of the present utility model.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
As shown in FIG. 2, the utility model provides a low-capacity low-voltage active filter device, which comprises a main circuit unit, a current detection unit, a main controller and a secondary controller.
And the main circuit unit is provided with N (N is equal to or greater than 1) buses connected in parallel between the alternating current power supply and the nonlinear load so as to generate compensation current to counteract harmonic waves or reactive currents in load currents on the buses.
And the current detection unit is connected to the bus to detect harmonic waves or reactive current of the load current in real time.
The main controller is connected with the current detection unit and the main circuit unit to calculate total reference current to be compensated according to harmonic waves or reactive currents of load current, and the total reference current is decomposed into N compensation current signals corresponding to the N main circuit units, and the main circuit unit is controlled to generate corresponding compensation currents, wherein each compensation current signal is 1/N of the total reference current.
And the auxiliary controller is provided with N-1 auxiliary circuit units which are respectively connected with the rest N-1 main circuit units and communicated with the main controller through optical fibers so as to control the main circuit units connected with the auxiliary controller to generate corresponding compensation currents according to the compensation current signals calculated by the main controller.
Specifically, the main controller receives harmonic or reactive current of load current detected by the current detection unit in real time and running states (including voltage data, current data, fault states and the like) uploaded by each auxiliary controller at fixed time, the main controller gathers and analyzes the information, first calculates total reference current to be compensated, then decomposes the total reference current into N compensation current signals corresponding to N main circuit units according to the number of the main circuit units, each compensation current signal is 1/N of the total reference current, sends the compensation current signal to N-1 auxiliary controllers in real time through optical fibers, and after each auxiliary controller receives the compensation current signal sent by the main controller, the auxiliary controllers together with the main controller respectively control the N main circuit units to generate corresponding compensation currents, and finally achieves the harmonic compensation function of the whole parallel device.
Specifically, after collecting harmonic wave in load current, the main controller carries out FFT conversion, processes harmonic wave component of corresponding times according to the set compensation times, namely, if the subharmonic wave is not compensated, clears the subharmonic wave component, then carries out inverse FFT conversion on the rest harmonic wave component, and obtains compensated harmonic wave component.
The main controller is a control core of the whole parallel device, the auxiliary controller only needs to execute commands of the main controller, and does not need to carry out additional analysis and calculation, so that N main circuit units connected in parallel can be coordinated uniformly, the main controller can realize closed loop control according to real-time detection results of the current detection units, namely current needing to be compensated in load current on a bus is sampled in real time, compensation current output by each main circuit unit is continuously corrected, when one main circuit unit is out of operation due to failure, the main controller receives a fault state uploaded by the auxiliary controller connected with the main circuit unit, the main controller immediately decomposes the total reference current into N-1 compensation current signals corresponding to N-1 main circuit units, the rest N-1 main circuit units are controlled to generate corresponding compensation currents, and at the moment, each compensation current signal is 1/N-1 of the total reference current, so that the compensation current can always offset harmonic waves or reactive current in the load current on the bus.
The main controller and the auxiliary controller both adopt a DSP chip and a CPLD chip, wherein the functions of the DSP chip are that A/D conversion, operation of instruction signals, processing of feedback signals and generation of PWM pulse signals are completed, the current detection unit sends electric signals into an ADC module of the DSP chip for A/D conversion, the DSP chip processes and calculates the acquired electric signals to obtain instruction current signals, the instruction current signals are sent to a full comparison unit of an EV module of the DSP chip, PWM pulse signal output is generated by setting values of corresponding registers, and each main circuit unit is controlled to generate compensation current. The CPLD chip provides PWM output control, hardware interlocking and dead zone control functions, the CPLD chip latches fault signals, when a main circuit unit breaks down (direct current voltage overvoltage, output compensation current overcurrent, short circuit and overheat), the CPLD immediately blocks PWM pulse signal output, safe operation of the device is guaranteed, the CPLD chip provides the hardware interlocking function to ensure that two IGBTs of the same bridge cannot be conducted simultaneously, when sudden power failure or power-on is prevented, an uncertain pulse signal causes bridge arm short circuit of an IGBT module to avoid short circuit faults caused by bridge arm direct connection, so that reliability requirements of the device are met, and the dead zone time control function of the CPLD chip ensures that after one IGBT on the same bridge arm is reliably turned off, the other IGBT can be conducted.
As shown in fig. 3, the main circuit unit specifically includes:
the inverter consists of a three-phase bridge inverter circuit and is connected to a bus between an alternating current power supply and a nonlinear load to generate compensation current to offset harmonic or reactive current in load current on the bus;
The intelligent power module is connected with the main controller or the auxiliary controller, and controls the on-off time of a power switch device on the inverter according to a PWM pulse signal sent by the main controller or the auxiliary controller so that the inverter generates compensation current with the same magnitude and opposite polarity as harmonic or reactive current in load current on a bus;
and the output filter is connected between the inverter and the bus to filter out higher harmonic waves generated by on-off of the power switch device in the compensation current generated by the inverter.
Because the inverter adopts the PWM technology, the output current of the inverter contains the current used for compensating harmonic waves and reactive power, and also contains higher harmonic waves generated by the on-off of a power switch device, the high-frequency electromagnetic induction generated by the higher harmonic waves has obvious influence on control, communication equipment, precision instruments and the like, additional loss of power transmission and distribution equipment (such as a power transmission line, a transformer and the like) can be brought, the additional higher harmonic waves are split by a power grid and a load after entering a bus, harmonic wave components can be generated at a public electrical environment and a user power receiving end, and pollution to both power supply and power consumption can be very serious. The output filter adopts LCRLL type output filter, can filter the harmonic wave that the inverter produced by the break-make of power switch device in compensating current, and its single-phase equivalent circuit diagram is as shown in fig. 4, LCRLL type output filter, designs series inductance L 01 in inverter side and guarantees the compensation ability of harmonic wave and reactive current, designs series inductance L O2 in electric wire netting side and improves the harmonic current filtering effect.
The current detection unit comprises an alternating current transformer and a current signal detection conditioning circuit, the alternating current transformer is connected to the bus, the current signal detection conditioning circuit is connected with the main controller, and the current signal detected by the alternating current transformer is converted and amplified and then is sent to the main controller.
The detection of the current signal adopts an alternating current transformer with the model of TA1321-3K, the input rated current is 20A, the output rated current is 10mA, and the sampling frequency can reach 20kHz. The circuit diagram of the current signal detection conditioning circuit is shown in fig. 5, and the detected alternating current signal is converted into alternating voltage of 1.5V through a resistor, and then is lifted to 0-3V through an amplifier so as to be sent into an ADC module of the DSP chip.
The foregoing is merely illustrative of the structures of this utility model and various modifications, additions and substitutions for those skilled in the art can be made to the described embodiments without departing from the scope of the utility model or from the scope of the utility model as defined in the accompanying claims.
Claims (9)
1. A low-capacity low-voltage active filter device, comprising:
The main circuit unit is connected in parallel on a bus between the alternating current power supply and the nonlinear load to generate compensation current to offset harmonic or reactive current in load current on the bus;
the current detection unit is connected to the bus to detect harmonic waves or reactive currents of load current in real time;
and the main controller is connected with the current detection unit and the main circuit unit and used for controlling the main circuit unit to generate compensation current with the same magnitude and opposite polarity as the harmonic or reactive current in the load current according to the harmonic or reactive current of the load current.
2. The low-capacity and low-voltage active filter device according to claim 1, wherein the main circuit units are arranged in a plurality of parallel, and the main controller calculates a total reference current to be compensated according to harmonic or reactive current of the load current and decomposes the total reference current into a plurality of compensation current signals corresponding to the main circuit units so as to control the main circuit units to generate corresponding compensation currents.
3. The low-capacity low-voltage active filter device according to claim 2, further comprising a plurality of sub controllers which are in communication connection with the main controller through optical fibers, wherein the main controller is in control connection with one main circuit unit, the plurality of sub controllers are respectively in control connection with other main circuit units, the main controller collects the running states of the sub controllers which are uploaded at regular time in real time and transmits compensation current signals corresponding to the main circuit units to the sub controllers, and the sub controllers control the main circuit units connected with the sub controllers to generate corresponding compensation currents according to the compensation current signals transmitted by the main controller.
4. A low-capacity low-voltage active filter device according to claim 3, wherein the main controller or the sub-controller outputs PWM pulse signals according to the compensation current signals corresponding to the main circuit units to control the main circuit units to generate the compensation currents.
5. The low-capacity low-voltage active filter device of claim 4, wherein said main circuit unit comprises:
An inverter connected to a bus between the ac power source and the nonlinear load to generate a compensation current to offset harmonics or reactive currents in the load current on the bus;
the intelligent power module is connected with the main controller or the auxiliary controller, and controls the on-off of a power switch device on the inverter through a PWM pulse signal sent by the main controller or the auxiliary controller so that the inverter generates compensation current with the same magnitude and opposite polarity as the harmonic or reactive current in the load current on the bus;
and the output filter is connected between the inverter and the bus to filter out higher harmonic waves generated by on-off of the power switch device in the compensation current generated by the inverter.
6. The low-capacity, low-voltage active filter device of claim 5, wherein said inverter is comprised of a three-phase bridge inverter circuit.
7. A low-capacity low-voltage active filter device as claimed in claim 5, wherein said output filter is a LCRLL-type output filter.
8. The low-capacity low-voltage active filter device according to claim 1, wherein the main controller and the sub-controller are DSP chips and CPLD chips.
9. The low-capacity low-voltage active filtering device according to claim 1, wherein the current detection unit comprises an alternating current transformer and a current signal detection conditioning circuit, the alternating current transformer is connected to the bus, the current signal detection conditioning circuit is connected to the main controller, and the current signal detected by the alternating current transformer is converted, amplified and sent to the main controller.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202323633018.9U CN222395454U (en) | 2023-12-29 | 2023-12-29 | A small capacity low voltage active filter device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202323633018.9U CN222395454U (en) | 2023-12-29 | 2023-12-29 | A small capacity low voltage active filter device |
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| Publication Number | Publication Date |
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| CN222395454U true CN222395454U (en) | 2025-01-24 |
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| CN202323633018.9U Active CN222395454U (en) | 2023-12-29 | 2023-12-29 | A small capacity low voltage active filter device |
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