CN110808592A - Direct-current side self-adaptive interphase voltage balance control method of star-connected STATCOM device - Google Patents
Direct-current side self-adaptive interphase voltage balance control method of star-connected STATCOM device Download PDFInfo
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- CN110808592A CN110808592A CN201911109520.5A CN201911109520A CN110808592A CN 110808592 A CN110808592 A CN 110808592A CN 201911109520 A CN201911109520 A CN 201911109520A CN 110808592 A CN110808592 A CN 110808592A
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- 238000000034 method Methods 0.000 title claims abstract description 15
- 230000016507 interphase Effects 0.000 title claims abstract description 9
- 239000003990 capacitor Substances 0.000 claims abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 238000002347 injection Methods 0.000 abstract description 3
- 239000007924 injection Substances 0.000 abstract description 3
- 238000001514 detection method Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 6
- 230000003044 adaptive effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
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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
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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
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
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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
- Y02E40/10—Flexible AC transmission systems [FACTS]
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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
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
Abstract
A direct-current side self-adaptive interphase voltage balance control method of a star-connected STATCOM device determines zero-sequence voltage injection control through detection and judgment of the voltage unbalance degree of a three-phase direct-current side of a chain type STATCOM. The invention can avoid the continuous increase of the unbalanced degree of the capacitor voltage at the direct current side, prevent the capacitor voltage of some chain links from being higher than other chain links to force the chain links to exit the operation, and ensure the safe and stable operation. The three-phase direct current side voltage balance during reactive compensation can be carried out under the unbalanced load working condition in the grid-connected operation process.
Description
Technical Field
The invention relates to a high-voltage chain type static synchronous compensator (hereinafter referred to as STATCOM), in particular to a DC-side adaptive interphase voltage balancing control method of a star-connected STATCOM device.
Background
The transmission of reactive power in a power grid has great influence on the operation of a power system, a large number of inductive reactive loads exist in the power grid, and meanwhile, the nonlinear, asymmetric and impact reactive loads in the power system are increased, so that the quality of electric energy is seriously influenced, and the problems of voltage fluctuation, high harmonic content, power impact and the like are caused.
Each phase of the chain type STATCOM is formed by cascading a series of inverter bridges, and the direct current sides of the inverter bridges are provided with independent capacitors, so that the chain type STATCOM has the advantages of high voltage resistance, small size, high economic benefit, fast dynamic response, convenience in control and the like, can be formed in a modularized mode, and is convenient to expand. The direct current side of the power system adopts a capacitor as an energy storage element, and can send or absorb reactive power to perform dynamic compensation under different operating conditions, so that the purposes of stabilizing voltage, improving the stability of the power system, adjusting power factors and the like are achieved. The reactive power regulation has the advantages of high response speed, low harmonic component of output current and low switching loss.
In an electric power system, due to the existence of three-phase unbalanced load, a large amount of unbalanced current may occur in the system due to possible asymmetric faults, and normal operation of the system is affected, so when a negative sequence component in the unbalanced current reaches a certain degree, the negative sequence current needs to be compensated for the unbalanced load system, and the STATCOM grid-connected inverter can cause three-phase active power imbalance due to self difference of each phase and negative sequence current compensation under an unbalanced working condition, so that voltage on a direct current side of each phase is unequal, and the output performance and reliability of the device are affected. Unbalanced dc side capacitor voltages can cause problems such as increased harmonic distortion of the STATCOM output voltage. When the unbalance degree of the capacitor voltage on the direct current side is continuously increased, the capacitor voltage of some chain links is higher than that of other chain links, and if the unbalance degree is serious, the chain links can be forced to exit the operation, so that the safe and stable operation of the device can be influenced, and the device can even be crashed. How to keep the voltage on the capacitor consistent is the key to the safe and reliable operation of the device.
Disclosure of Invention
The invention provides a direct-current side adaptive interphase voltage balance control method of a star-connected STATCOM device, aiming at the problems in the prior art, and the method ensures the safe and stable operation of the STATCOM device and improves the working performance by injecting zero-sequence voltage of the star-connected STATCOM device into a three-phase grid system of an unbalanced load. The three-phase direct current side voltage balance during reactive compensation can be carried out under the unbalanced load working condition in the grid-connected operation process.
In order to solve the technical problems, the technical solution of the invention is as follows:
a star-connected chain-type STATCOM device direct current side self-adaptive interphase voltage balance control method is characterized by comprising the following steps of:
1) three-phase direct current side voltage U at connecting point of STATCOM device connected to three-phase grid system through phase-locked loopdc,a，Udc,b，Udc,cThe phase angle θ of the fundamental positive sequence voltage is ω t, and the average value of the three-phase dc-side capacitor voltage is calculated according to the following formula:
the maximum value and the minimum value of the three-phase direct-current side voltage are respectively U through comparisondc,max，Udc,min；
2) Detecting three-phase current of a three-phase power grid system: the positive sequence current and the negative sequence current component effective values in the three-phase current of the system obtained by the way of park conversion, separation and re-filtering are respectively I+，I-，
3) Compensation:
when in use
Then, the instantaneous value of the output current of the STATCOM device is calculated according to the following formula:
in the formula I+，θ+Respectively injecting a positive sequence current effective value and a phase; i is-，θ_The STATCOM device outputs current according to the instantaneous value and adds the current into three-phase current for compensation;
when in use
Then, the instantaneous value of the zero sequence voltage to be injected is calculated according to the following formula:
and the STATCOM device outputs the zero sequence voltage to the alternating current side for compensation.
Compared with the prior art, the invention has the beneficial effects that:
the voltage balance control of the direct current side of the STATCOM is directly related to the quality of an output waveform of the alternating current side of the STATCOM, reactive power compensation capability and dynamic response speed of the device. The invention provides reliable support for the STATCOM to perform reactive compensation on an electric power system under an unbalanced load working condition, self-adaptive distribution is performed on three-phase active power, the three-phase direct-current side voltage interphase balance of the STATCOM in grid-connected operation is ensured, the continuous increase of the unbalanced degree of the direct-current side capacitor voltage is avoided, the capacitor voltage of certain chain links is prevented from being higher than other chain links to force the chain links to exit from operation, the safe and stable operation is ensured, and the exertion of the reactive compensation performance of the STATCOM is ensured.
Drawings
FIG. 1 is a main circuit structure diagram of a star-connected cascade STATCOM;
FIG. 2 is a block diagram of reactive compensation control under unbalanced system conditions;
fig. 3 is a voltage balance control block diagram of the zero sequence voltage injection dc side under the unbalanced condition of the system.
Detailed Description
The technical solution of the present invention is described in detail below with reference to the accompanying drawings and examples, which are implemented on the premise of the technical solution of the present invention, and give detailed embodiments and specific operation procedures, but the application scope of the present invention is not limited to the following examples.
Referring to fig. 1, fig. 2, and fig. 3, fig. 1 is a structural diagram of a main circuit of a star-connected cascade STATCOM, fig. 2 is a block diagram of reactive compensation control under an unbalanced condition of a system, and fig. 3 is a block diagram of zero-sequence voltage injection dc-side voltage balance control under the unbalanced condition of the system.
It can be seen from the figure that the direct current side adaptive interphase voltage balance control method of the star-connected type STATCOM device of the invention is characterized in that each phase of a main circuit of the star-connected type STATCOM device is formed by cascading the same number of units H bridges, three-phase chain links are in star connection, one ends of the three-phase chain links are connected together, and the other ends of the three-phase chain links are respectively connected with a three-phase grid system with unbalanced load, and the method comprises the following steps:
1) three-phase direct current side voltage U at connecting point of STATCOM device connected to three-phase grid system through phase-locked loopdc,a，Udc,b，Udc,cThe phase angle θ of the fundamental positive sequence voltage is ω t, and the average value of the three-phase dc-side capacitor voltage is calculated according to the following formula:the maximum value and the minimum value of the three-phase direct-current side voltage are respectively U through comparisondc,max，Udc,min；
2) Detecting three-phase current of a three-phase power grid system: the positive sequence current and the negative sequence current component effective values in the three-phase current of the system obtained by the way of park conversion, separation and re-filtering are respectively I+，I_，
3) Compensation:
when in use
Then, the instantaneous value of the output current of the STATCOM device is calculated according to the following formula:
in the formula I+，θ+Respectively injecting a positive sequence current effective value and a phase; i is-，θ-The STATCOM device outputs current according to the instantaneous value and adds the current into three-phase current for compensation;
when in use
Then, the instantaneous value of the zero sequence voltage to be injected is calculated according to the following formula:
and the STATCOMOMzhzhzhzhh outputs the zero-sequence voltage to the alternating current side for compensation.
Experiments show that the invention can avoid the continuous increase of the unbalanced degree of the capacitance voltage at the direct current side, prevent the capacitance voltage of some chain links from being higher than other chain links to force the chain links to exit from operation, and ensure safe and stable operation. The three-phase direct current side voltage balance during reactive compensation can be carried out under the unbalanced load working condition in the grid-connected operation process.
Claims (1)
1. A star-connected chained STATCOM device direct current side self-adaptive interphase voltage balance control method is characterized in that each phase of a main circuit of the star-connected chained STATCOM device is formed by cascading H bridges with the same number of units, three-phase chain links are connected in a star shape, one ends of the three-phase chain links are connected together, and the other ends of the three-phase chain links are connected with a three-phase grid system with unbalanced load respectively, and the method comprises the following steps:
1) three-phase direct current side voltage U at connecting point of STATCOM device connected to three-phase grid system through phase-locked loopdc,a，Udc,b，Udc,cThe phase angle θ of the fundamental positive sequence voltage is ω t, and the average value of the three-phase dc-side capacitor voltage is calculated according to the following formula:
obtaining three-phase direct current by comparisonThe maximum value and the minimum value of the side voltage are respectively Udc,max，Udc,min；
2) Detecting three-phase current of a three-phase power grid system: the positive sequence current and the negative sequence current component effective values in the three-phase current of the system obtained by the way of park conversion, separation and re-filtering are respectively I+，I_，
3) Compensation:
when in use
Then, the instantaneous value of the output current of the STATCOM device is calculated according to the following formula:
in the formula I+，θ+Respectively injecting a positive sequence current effective value and a phase; i is-，θ-The STATCOM device outputs current according to the instantaneous value and adds the current into three-phase current for compensation;
when in use
Then, the instantaneous value of the zero sequence voltage to be injected is calculated according to the following formula:
and the STATCOMOMzhzhzhzhh outputs the zero-sequence voltage to the alternating current side for compensation.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101707374A (en) * | 2009-11-25 | 2010-05-12 | 中国科学院电工研究所 | Direct current (DC) side capacitor voltage balancing control circuit for H-bridge cascaded active power filter |
| CN104810835A (en) * | 2015-04-23 | 2015-07-29 | 许继电气股份有限公司 | STATCOM unbalanced control method and zero-sequence component generating method thereof |
| CN110112753A (en) * | 2019-06-15 | 2019-08-09 | 南京浦马电力电子有限公司 | A kind of alternate DC voltage balance control method of star-like connection cascade STATCOM |
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- 2019-11-12 CN CN201911109520.5A patent/CN110808592A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101707374A (en) * | 2009-11-25 | 2010-05-12 | 中国科学院电工研究所 | Direct current (DC) side capacitor voltage balancing control circuit for H-bridge cascaded active power filter |
| CN104810835A (en) * | 2015-04-23 | 2015-07-29 | 许继电气股份有限公司 | STATCOM unbalanced control method and zero-sequence component generating method thereof |
| CN110112753A (en) * | 2019-06-15 | 2019-08-09 | 南京浦马电力电子有限公司 | A kind of alternate DC voltage balance control method of star-like connection cascade STATCOM |
Non-Patent Citations (4)
| Title |
|---|
| 徐海明 等: "《现代电源应用技术手册》", 31 May 2007 * |
| 王志冰 等: "H 桥级联多电平变流器的直流母线电压平衡控制策略", 《中国电机工程学报》 * |
| 罗锐等: "星接串联 H 桥多电平静止无功发生器不平衡补偿分析", 《中国电机工程学报》 * |
| 黄北军等: "静止无功发生器入网动态响应性能检测方法", 《电工技术》 * |
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Application publication date: 20200218 |