CN113036766A - Active power filter and control method and device thereof - Google Patents
Active power filter and control method and device thereof Download PDFInfo
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- CN113036766A CN113036766A CN202110343056.7A CN202110343056A CN113036766A CN 113036766 A CN113036766 A CN 113036766A CN 202110343056 A CN202110343056 A CN 202110343056A CN 113036766 A CN113036766 A CN 113036766A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
- H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
- H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/20—Active power filtering [APF]
Abstract
The invention belongs to the technical field of active power filters, and particularly relates to an active power filter and a control method and device thereof. The three-phase power supply comprises a three-phase inverter, a three-phase rectifier and a three-phase power supply; the alternating current side of the three-phase inverter is used for connecting a power grid where the nonlinear load is located, and the direct current side of the three-phase inverter is connected with the direct current side of the three-phase rectifier; and the alternating current side of the three-phase rectifier is connected with the three-phase power supply. The active power filter can control the three-phase inverter to generate harmonic suppression current with the same magnitude and the opposite direction as the harmonic current component and inject the harmonic suppression current into a power grid, so that the aim of harmonic suppression is fulfilled, the active power filter has the characteristics of high controllability and quick response, the characteristics are not influenced by a system, the harmonic amplification threat is avoided, the reliability of safe operation of the power grid and a transformer is improved, and the active power filter has great practical significance to the whole power system.
Description
Technical Field
The invention belongs to the technical field of active power filters, and particularly relates to an active power filter and a control method and device thereof.
Background
In recent years, a rectifying device, a variable frequency speed regulation device, an industrial power supply and various power electronic devices in a power distribution network are added continuously, so that the voltage and the current of a power system are distorted due to the nonlinearity and the imbalance of loads, and the power supply quality is seriously influenced. Therefore, the problems of harmonic waves and reactive power in the power system are solved, and the problem that the improvement of the power supply quality of the power grid cannot be ignored is becoming more and more.
Due to the development of power electronics, higher demands are made on the quality of power supply. While the traditional harmonic suppression and reactive compensation mainly adopt LC filters, and the LC filters are widely applied to industrial production due to simple structure, low cost and mature technology. But the method also has certain defects, so that a plurality of problems are generated in the application. With the development of power electronic technology, active power filters for effectively suppressing harmonics and compensating for reactive power have been proposed. Compared with a passive power filter, the active power filter has high controllability and quick response characteristics, can track and compensate each harmonic wave and automatically generate reactive power which needs to be changed, is not influenced by a system, has no harmonic amplification threat, is a novel power electronic device which can effectively inhibit the harmonic wave and compensate the reactive power, and brings huge economic benefits and social benefits along with the continuous popularization and application of the active power filter in China.
In China, a static reactive power compensation device taking a thyristor as a core has become a mainstream product for reactive power compensation in an electric power system for 80 years. In 1977, after the first thyristor static var compensation demonstration of the GE company in the United states succeeded in operation, in the second year, the electric power research institute and the West electric company developed the first static var compensation device which is composed of thyristors as cores and was put into operation. Then, many large-scale well-known electric companies in the world compete to release respective similar series products, such as Thyristor Controlled Reactors (TCR), that is, two antiparallel thyristors are connected in series and one Reactor is connected in parallel to a power grid, and reactive power absorbed by a compensator is changed by adjusting the trigger angle of the thyristors; a Thyristor 2-tube switching Capacitor (Thyristor-TSC) is connected into or separated from a power grid through two anti-parallel thyristors through the Capacitor, the thyristors replace a conventional mechanical switch to solve the problem of frequent switching of the Capacitor, the series small inductor is used for inhibiting impact current generated when the Capacitor is Switched into the power grid, the number of groups of the Switched Capacitor is determined according to the magnitude of reactive current, but the series small inductor can only be used for carrying out graded regulation on the reactive current; thyristor controlled reactors and Fixed capacitors (Fixed capacitors-FC), and hybrid devices based on the above (e.g., TCR + TSC, TCR + FC). The dynamic reactive power compensation device that realizes continuity mainly by adjusting the conduction angle of the thyristor is referred to as a Static Var Compensator (SVC). Compared with a rotary phase modulator, the static reactive compensation device has obvious advantages in aspects of rapidity of adjustment, economical efficiency of operation and the like. Therefore, in the last forty-five decades, the market of the reactive power compensator has been rapidly and stably growing worldwide, and the reactive power compensator becomes a leading product in the field of dynamic reactive power compensation and achieves better economic benefits.
As early as 1971, h.sasaki et al completely described the basic principle of APF-, and l.gyugyi et al proposed APF constructed by a high-power transistor PWM inverter in 1976 and formally established the concept of active filtering, and proposed the basic topology and control method of the main circuit of the active filter, and in 1983, h.akagi et al proposed the instantaneous reactive power theory and pq detection method, which provided a theoretical basis for instantaneous detection of distortion current of a three-phase power system; meanwhile, new fast high-capacity power switching devices such as transistors, turn-off thyristors, electrostatic induction thyristors, field effect transistors, insulated gate bipolar transistors and the like are emerging in succession, and the PWM modulation technology, the microcomputer control technology and the digital signal processing technology are all greatly improved. This greatly promotes the development of active power filtering technology, and makes the APF really enter the industrial practical stage. As an important technology for improving the quality of electric energy, an active filter has been widely used in various production departments in advanced industrial countries such as the united states and japan, the number and capacity of harmonic compensation have been gradually increased, and the application field has been gradually developed from compensating the harmonic of a user to improving the quality of power supply of the entire power system. In japan, as the most advanced countries of power electronics technology, 200 or more APFs have been put into operation by 2001, and the maximum capacity of one APF reaches 20 MVA.
In recent years, the active filter becomes a hot point for the research of the electric power industry in China once, the result is outstanding, and the original trial operation is developed to the industrial application stage. The active higher harmonic suppression device jointly developed and researched by the North China electric power test research institute, the automatic research institute of the metallurgy department and the Beijing Power supply company is put into industrial operation in the central substation of the Beijing Wood factory in 1992, the harmonic tracking and compensation effects are not very ideal, but a sequence screen is opened for the harmonic treatment industry in China; the western-ampere traffic university is a new research show of the active filter, and the proposed method of using the quadruple converter as the main circuit of the high-capacity active filter effectively solves the contradiction between high capacity and switching frequency and is put into practice. The research field of the active power filter is very distinctive, and products have various characteristics.
Therefore, it is necessary to provide a simple and reliable active power filter.
Disclosure of Invention
The invention aims to provide a simple and reliable active power filter, and provides a control method and a control device for harmonic compensation by using the active power filter.
In order to solve the technical problems, the technical scheme and the corresponding beneficial effects of the technical scheme are as follows:
the invention provides an active power filter, which comprises a three-phase inverter, a three-phase rectifier and a three-phase power supply, wherein the three-phase inverter is connected with the three-phase rectifier;
the alternating current side of the three-phase inverter is used for connecting a power grid where the nonlinear load is located, and the direct current side of the three-phase inverter is connected with the direct current side of the three-phase rectifier;
and the alternating current side of the three-phase rectifier is connected with the three-phase power supply.
The beneficial effects of the above technical scheme are: the active power filter can control a three-phase inverter in the active power filter to generate a harmonic suppression current with the same magnitude and the opposite direction to a harmonic current component according to the current condition in a power grid, and the harmonic suppression current is injected into the power grid, so that the aim of harmonic suppression is fulfilled, and automatic tracking compensation of each harmonic is realized. In the same way, the negative sequence current component and the reactive current of the asymmetric three-phase circuit can be compensated. On the whole, the active power filter has the characteristics of high controllability and quick response, the characteristics of the active power filter are not influenced by a system, the harmonic amplification threat is avoided, the reliability of safe operation of a power grid and a transformer is improved, and the active power filter has great practical significance to the whole power system.
Furthermore, a resistor and a bypass switch connected in parallel with the resistor are connected in series on a line between the direct current side of the three-phase inverter and the direct current side of the three-phase rectifier.
Further, the alternating current side of the three-phase inverter is used for connecting the power grid through a reactor.
Further, the active power filter further comprises a current transformer for detecting the load current.
Furthermore, a capacitor is arranged between two ends of the direct current side of the three-phase inverter.
Further, the three-phase inverter is a three-phase bridge inverter, and each controllable switching device in the three-phase bridge inverter comprises an IGBT and a freewheeling diode connected in anti-parallel with the IGBT.
Further, the three-phase rectifier is a three-phase bridge rectifier, and each controllable switching device in the three-phase bridge rectifier comprises an IGBT and a freewheeling diode connected in anti-parallel with the IGBT.
The invention also provides a control method of the active power filter, which comprises the following steps:
detecting load current through a current transformer, and extracting harmonic current components in the load current;
and outputting a control signal to the three-phase inverter according to the extracted harmonic current component, so that the three-phase inverter generates a harmonic suppression current which has the same magnitude and the opposite direction with the harmonic current component and is injected into the power grid.
The beneficial effects are as follows: according to the control method, the current transformer is used for detecting the load current, the harmonic current component is extracted from the load, and then the three-phase inverter in the active power filter is controlled to generate a harmonic suppression current which is equal to the harmonic current component in magnitude and opposite in direction and is injected into a power grid, so that the purpose of harmonic suppression is achieved, and automatic tracking compensation of each harmonic is achieved. The method is simple and reliable, the whole power system is not threatened by harmonic amplification, the reliability of safe operation of the power network and the transformer is improved, and the method has great practical significance to the whole power system.
The present invention also provides a control apparatus for an active power filter, which is characterized by comprising a memory and a processor, wherein the processor is used for executing instructions stored in the memory to achieve the above-described control method for the active power filter, and achieves the same beneficial effects as the method.
Drawings
Fig. 1 is a circuit diagram of an active power filter of the present invention;
fig. 2 is a block diagram of a control device of the active power filter of the present invention;
1-a power grid, 2-a first reactor, 3-a current transformer, 4-a nonlinear load, 5-a second reactor, 6-a capacitor, 7-a resistor, 8-a bypass switch, 9-a three-phase inverter, 10-a three-phase rectifier and 11-a three-phase power supply.
Detailed Description
Active power filter embodiment:
an embodiment of the active power filter of the present invention is shown in fig. 1, and is used for suppressing harmonic current in the power distribution network in fig. 1.
The grid 1 is connected to a nonlinear load 4 via a three-phase line to supply the nonlinear load 4 with power, and a first reactor 2 is provided on the line on the grid side.
The active power filter comprises a three-phase inverter 9, a three-phase rectifier 10, a three-phase power supply 11, a capacitor 6, a resistor 7, a bypass switch 8 and a current transformer 3. The ac side of the three-phase inverter 9 is used for connecting the grid 1 via the second reactor 5, the dc side of the three-phase inverter 9 is connected to the dc side of the three-phase rectifier 10, and the dc side of the three-phase rectifier 10 is connected to the three-phase power supply 11. A resistor 7 is connected in series to a dc line between the dc side of the three-phase rectifier 10 and the dc side of the three-phase inverter 9, a bypass switch 8 is connected in parallel to both ends of the resistor 7, and the resistor 7 is a soft start resistor and functions to prevent current surge. Two ends of the direct current side of the three-phase inverter 9 are connected with a capacitor 6, and the current transformer 3 is used for detecting load current. The three-phase inverter 9 is a three-phase bridge inverter, the three-phase rectifier 10 is a three-phase bridge rectifier, and the controllable switching devices in the three-phase inverter 9 and the three-phase rectifier 10 are both composed of an IGBT and a freewheeling diode connected in anti-parallel with the IGBT.
Moreover, the whole system is also provided with a DSP; the DSP is connected with the bypass switch 8 through a corresponding line to control the action of the bypass switch 8; the DSP is also connected with a current transformer 3 through a corresponding line to obtain load current; moreover, the DSP also connects each controllable switching device in the three-phase inverter 9 and the three-phase rectifier 10 through a corresponding line to output a PWM wave to control the three-phase inverter 9 and the three-phase rectifier 10 to operate.
The working process of the active power filter for harmonic suppression is as follows: detecting load current through a current transformer 3, transmitting the load current to a DSP, and extracting harmonic current components and fundamental wave components in the load current through calculation of the DSP; then, the compensation current is calculated according to the extracted harmonic current component, further the trigger pulse of each controllable switch device in the three-phase inverter 9 is calculated, the DSP outputs the trigger pulse to the three-phase inverter 9, the three-phase inverter generates a harmonic suppression current which is equal to the harmonic current component in magnitude and opposite in direction, and the harmonic suppression current is injected into a power grid, so that only the fundamental component exists in the power grid, and the purpose of harmonic suppression is achieved. According to the same principle, the active power filter can also compensate the negative sequence current component and the reactive current of the asymmetric three-phase circuit.
In the embodiment, the controllable switching devices in the three-phase inverter and the three-phase rectifier select the IGBTs. Other common controllable switching devices in the prior art, such as MOS transistors, can also be used as other embodiments.
In conclusion, the active power filter of the invention can control the three-phase inverter in the active power filter to generate a harmonic suppression current with the same magnitude and the opposite direction to the harmonic current component according to the current condition in the power grid, and inject the harmonic suppression current into the power grid, thereby achieving the purpose of harmonic suppression and realizing automatic tracking compensation of each subharmonic. In the same way, the negative sequence current component and the reactive current of the asymmetric three-phase circuit can be compensated. On the whole, the active power filter has the characteristics of high controllability and quick response, the characteristics of the active power filter are not influenced by a system, the harmonic amplification threat is avoided, the reliability of safe operation of a power grid and a transformer is improved, and the active power filter has great practical significance to the whole power system.
The embodiment of the control method comprises the following steps:
the overall process of the control method embodiment of the active power filter of the present invention is the process of performing harmonic suppression introduced in the active power filter embodiment. Since the process has been described in detail in the active power filter embodiment, it is not described here in detail.
Control device embodiment:
an embodiment of the control device of the active power filter according to the present invention is shown in fig. 2, and includes a memory, a processor, and an internal bus, where the processor and the memory complete mutual communication and data interaction through the internal bus. The memory comprises at least one software functional module stored in the memory, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory, so as to realize the control method of the active power filter in the embodiment of the active power filter.
The processor may be a DSP introduced in the embodiment of the active power filter, or may also be a processing device such as a microprocessor MCU.
The memory can be various memories for storing information by using an electric energy mode, such as RAM, ROM and the like; various memories for storing information by magnetic energy, such as hard disk, floppy disk, magnetic tape, magnetic core memory, bubble memory, U disk, etc.; various memories for storing information optically, such as CDs, DVDs, etc.; of course, other forms of memory are possible, such as quantum memory, graphene memory, and the like.
Claims (9)
1. An active power filter is characterized by comprising a three-phase inverter, a three-phase rectifier and a three-phase power supply;
the alternating current side of the three-phase inverter is used for connecting a power grid where the nonlinear load is located, and the direct current side of the three-phase inverter is connected with the direct current side of the three-phase rectifier;
and the alternating current side of the three-phase rectifier is connected with the three-phase power supply.
2. Active power filter according to claim 1, characterized in that a resistor and a bypass switch in parallel with the resistor are arranged in series on the line between the dc-side of the three-phase inverter and the dc-side of the three-phase rectifier.
3. An active power filter according to claim 1, wherein the ac side of the three-phase inverter is used to connect to the grid through a reactor.
4. The active power filter of claim 1, further comprising a current transformer for detecting a load current.
5. The active power filter of claim 1, wherein a capacitance is provided between two ends of the dc side of the three-phase inverter.
6. An active power filter according to any one of claims 1 to 5, wherein the three-phase inverter is a three-phase bridge inverter, and each controllable switching device in the three-phase bridge inverter comprises an IGBT and a freewheeling diode connected in anti-parallel with the IGBT.
7. An active power filter according to any one of claims 1 to 5 wherein the three-phase rectifier is a three-phase bridge rectifier and each controllable switching device in the three-phase bridge rectifier comprises an IGBT and a freewheeling diode connected in anti-parallel with the IGBT.
8. A method of controlling an active power filter according to claim 4, comprising the steps of:
detecting load current through a current transformer, and extracting harmonic current components in the load current;
and outputting a control signal to the three-phase inverter according to the extracted harmonic current component, so that the three-phase inverter generates a harmonic suppression current which has the same magnitude and the opposite direction with the harmonic current component and is injected into the power grid.
9. A control apparatus of an active power filter, comprising a memory and a processor for executing instructions stored in the memory to implement the control method of the active power filter according to claim 8.
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| CN201608532U (en) * | 2010-02-10 | 2010-10-13 | 南京亚派科技实业有限公司 | Active power filter system |
| CN102570465A (en) * | 2012-01-06 | 2012-07-11 | 中南大学 | Hybrid active power filter and SVPWM method based on filter |
| CN103701127A (en) * | 2013-12-27 | 2014-04-02 | 国电南京自动化股份有限公司 | Novel active power filtering device and control method thereof |
| CN105490275A (en) * | 2016-01-26 | 2016-04-13 | 云南电网有限责任公司电力科学研究院 | Parallel hybrid active filter and quality detection method thereof |
| CN106374478A (en) * | 2015-07-24 | 2017-02-01 | 利思电气（上海）有限公司 | Outdoor active power filter device with reactive power dispatch function |
| CN106374489A (en) * | 2016-09-18 | 2017-02-01 | 国网福建省电力有限公司 | Nine-switch tube inverter-based harmonic compensation method of active power filter |
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2021
- 2021-03-30 CN CN202110343056.7A patent/CN113036766A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201608532U (en) * | 2010-02-10 | 2010-10-13 | 南京亚派科技实业有限公司 | Active power filter system |
| CN102570465A (en) * | 2012-01-06 | 2012-07-11 | 中南大学 | Hybrid active power filter and SVPWM method based on filter |
| CN103701127A (en) * | 2013-12-27 | 2014-04-02 | 国电南京自动化股份有限公司 | Novel active power filtering device and control method thereof |
| CN106374478A (en) * | 2015-07-24 | 2017-02-01 | 利思电气（上海）有限公司 | Outdoor active power filter device with reactive power dispatch function |
| CN105490275A (en) * | 2016-01-26 | 2016-04-13 | 云南电网有限责任公司电力科学研究院 | Parallel hybrid active filter and quality detection method thereof |
| CN106374489A (en) * | 2016-09-18 | 2017-02-01 | 国网福建省电力有限公司 | Nine-switch tube inverter-based harmonic compensation method of active power filter |
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Application publication date: 20210625 |