CN103441507A - Control method of cascade STATCOM on unbalanced working condition - Google Patents
Control method of cascade STATCOM on unbalanced working condition Download PDFInfo
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Abstract
The invention provides a novel control method of positive sequence-negative sequence decoupling PWM. The novel control method of positive sequence-negative sequence decoupling PWM is used for solving the problem of control over a cascade STATCOM on the unbalanced working condition, a decoupling control equation of a system in a positive sequence environment and a decoupling control equation of the system in a negative sequence environment are derived in detail, and the reactive power compensation working mode and voltage control working mode of the novel control method of positive sequence-negative sequence decoupling PWM are analyzed. When the degree of voltage unbalanced of the system is smaller than 2%, positive sequence-negative sequence decoupling PWM control in the reactive power compensation working mode is adopted to achieve the normal reactive power compensation function of the cascade STATCOM on the unbalanced working condition; when the degree of voltage unbalanced of the system is larger than 2%, positive sequence-negative sequence decoupling PWM control in the voltage control working mode is adopted to achieve the function of adjusting voltage balance of the system of the novel control method of positive sequence-negative sequence decoupling PWM. According to simulation and experiments, the control method of positive sequence-negative sequence decoupling PWM can be used for effectively solving the problem of safe operation of the cascade STATCOM on the unbalanced working condition, and achieving maximum utilization of the cascade STATCOM.
Description
Technical field
The present invention aim to provide a kind of under the uneven operating mode of system voltage the control method of cascade STATCOM, can effectively solve the normal operation problem of cascade STATCOM under uneven operating mode, two kinds of mode of operations contribute to realize the maximum using of cascade STATCOM, have very high engineering practical value.
Background technology
But cascade STATCOM due to modularization, without plurality of advantages such as access transformer etc. by extensive concern.It has phase-splitting regulating power and variable modulation ratio simultaneously, makes it have the potentiality of regulating system Voltage unbalance concurrently in reactive power compensation.At present, the most of control strategies of cascade STATCOM all are operated under balance condition, also rarely have document for it control under uneven operating mode do correlative study.A literary composition proposes to compensate imbalance of three-phase voltage by STATCOM in the 28th phase in 2004 " electric power network technique ", " to utilize Distribution Network Static Reactive Compensator to improve the method for distribution network electric energy quality ", and it is feasible showing to utilize STATCOM to maintain the system voltage balance.In the 26th phase in 2006 " Proceedings of the CSEE ", " for the research of the transformer isolation type chain type D-STATCOM of imbalance compensation " literary composition proposes the control method of the transformer isolation type chain type STATCOM of anti-fault, but be not suitable for transformerless cascade STATCOM system, range of application is narrower.In the 24th phase in 2009 " IEEE Trans. on Power Electronics ", " Control of a cascade STATCOM with star configuration under unbalanced conditions " literary composition is for the cascade STATCOM of Y-connection, propose output positive sequence, negative phase-sequence and residual voltage and maintain stable state, but the method is not suitable for the cascade STATCOM that triangle connects.In the 37th phase in 1997 " Tsing-Hua University's journal ", " Operation and control of ASVG in the asymmetric situation of system " literary composition proposes asymmetric vector control and also can well maintain the balance of system voltage, but has sacrificed the reactive response speed of device.The meritorious idle decoupling zero PWM that in the 25th phase in 2005 " Proceedings of the CSEE ", " the chain type STATCOM Dynamic Control Strategy research based on the method for inverse Active-reactivepower decoupled control " literary composition proposes based on method of inverse controls, make cascade STATCOM there is reactive response speed fast under the three-phase voltage poised state, but do not solve its operation problem under imbalance of three-phase voltage.In the 25th phase in 2005 " Proceedings of the CSEE ", " research of the chain type STATCOM Dynamic Control Strategy based on anti-Fault Control " literary composition proposes asymmetric vector control, the phase-splitting transient current is controlled controls with meritorious idle decoupling zero the control method combined, improved the reactive response speed of device, but need to carry out Fourier transform to electric current and voltage, calculate comparatively complicated.
Summary of the invention
The present invention is directed to the control problem of cascade STATCOM under uneven operating mode, the decoupling zero governing equation of the system of having derived in detail under positive sequence and negative phase-sequence environment, the control method that proposes a kind of new positive sequence-negative phase-sequence decoupling zero PWM solves the safe and stable operation problem of cascade STATCOM under uneven operating mode, and has inquired into two kinds of mode of operations under the method: reactive power compensation pattern and voltage mode control.
Embodiment is as follows:
When the system voltage balance, its negative phase-sequence content is 0, thus the Active-reactivepower decoupled control when decoupling zero governing equation under the positive sequence environment can be with reference to the three phase network balance of voltage, therefore positive sequence decoupling zero PWM equation is:
In formula:
u cd+ * ,
u cq+ * being respectively positive sequence gains merit and the reactive voltage instruction;
i d+ * ,
i q+ * being respectively positive sequence gains merit and referenced reactive current;
u sd+ ,
u sq+ being respectively net side positive sequence gains merit and reactive voltage.
Under the negative phase-sequence environment, the meritorious and reactive power of cascade STATCOM output is:
In formula:
u cd- * ,
u cq- * being respectively negative phase-sequence gains merit and the reactive voltage instruction;
i d- * ,
i q- * being respectively negative phase-sequence gains merit and referenced reactive current.
Meritorious and the reactive power at points of common connection PCC place is:
In formula:
u sd- ,
u sq- being respectively net side negative phase-sequence gains merit and reactive voltage.
Meritorious and the reactive power that output connects reactance consumption is:
From principle of energy balance:
Known negative phase-sequence decoupling zero PWM equation is:
Positive sequence that hence one can see that-negative phase-sequence decoupling zero PWM equation is:
In conjunction with above-mentioned analysis, can derive concrete control block diagram and see Figure of description 1.
In figure, three phase static abc to positive sequence dq+ transformation of coordinates matrix is:
Three phase static abc to negative phase-sequence dq-transformation of coordinates matrix is:
The DC voltage set-point
u dcref with actual value
u dc relatively after PI, obtain the instruction of positive sequence active current
i d+ *,
u abc through T
abc/dq- after coordinate transform, by trapper, obtain the negative phase-sequence active voltage
u d- with the negative phase-sequence reactive voltage
u q- .When system voltage is uneven,
u a, b, c -≠ 0,
u d, q- ≠ 0; Control target and be and wish that cascade STATCOM sends the negative sequence voltage with system negative sequence voltage equal and opposite in direction, opposite direction, the negative phase-sequence content that makes system voltage is 0,
u a, b, c- =0, need only
u d, q- =0 gets final product.So utilize
u d- ,
u q- with 0 make difference, after regulating by PI, obtain the instruction of negative phase-sequence active current
i d- *with the negative phase-sequence referenced reactive current
i q- *.
When the positive sequence referenced reactive current
i q+ *reactive power Q and the reactive power set-point Q detected by Instantaneous Power Theory
ref relatively after PI, obtain, when in figure, switch is positioned at 1 position, now cascade STATCOM is in the reactive power compensation pattern, take the reactive power of bucking-out system as main, when being usually operated at degree of unbalance and being less than 2%.
When
u abc through T
abc/dq+ after coordinate transform, the positive sequence voltage actual value obtained by the amplitude computing and line voltage set-point
u pCC relatively after PI, obtain
i q+ *, when switch is positioned at 2 position, now cascade STATCOM, in voltage mode control, be take the control system balance of voltage as main, when being usually operated at degree of unbalance and being greater than 2%.
the simulation and experiment interpretation of result:
This paper has carried out simulation analysis based on matlab7.0 to carried control method, and simulation parameter is as follows: system line voltage
u s =311V, mains frequency
f s =50Hz, connect inductance L=5mH, DC bus capacitor C=2000uF, capacitance voltage set-point
u dcref =200V, single-phase cascade module is counted N=5.
The reactive power compensation characteristic of cascade STATCOM while for the system degree of unbalance, being less than 2%, done following emulation: drop into reactive load during 0.1s, accompanying drawing 2 and accompanying drawing 3 are the power factor change situation of A circuitry phase before and after compensation, more known, before compensation, A phase power factor is 0.85, substantially reach 1 after compensation, the positive sequence in the reactive power compensation mode of operation-negative phase-sequence decoupling zero PWM controls the function that can effectively realize the System Reactive Power compensation as seen.
The control characteristic of positive sequence in voltage mode control while for degree of unbalance, being greater than 2%-negative phase-sequence decoupling zero PWM, done following emulation: the compensation effect of cascade STATCOM while adopting uneven resistive load to come analog voltage uneven.Accompanying drawing 4 is for dropping into the waveform of the front system voltage of cascade STATCOM, and due to the impact of uneven resistive load, obvious imbalance has appearred in three-phase voltage, and degree of unbalance reaches 12.5%.Accompanying drawing 5, for its voltage oscillogram after dropping into, contrasts two figure can obviously find, its three-phase voltage reaches unanimity substantially, and waveform quality is better, and degree of unbalance drops to 0.56%.Therefore adopt positive sequence in the voltage control mode of operation-negative phase-sequence decoupling zero PWM control method can effectively solve the problem of three-phase system Voltage unbalance.
In order to verify the validity of positive sequence-negative phase-sequence decoupling zero PWM control method, carried out experimental study.In experiment, load is the three-phase commutation bridge with the resistance sense load.Wherein, accompanying drawing 6 and accompanying drawing 7 are respectively the load end three-phase voltage waveform after cascade STATCOM drops into front and input.Before input, the system three-phase voltage is respectively 351V, 420V, 387V, and degree of unbalance reaches 8.85%.After input, the system three-phase voltage is respectively 397.2V, 398.8V, 396.5V, and degree of unbalance drops to 0.45%.Visible, after compensation, the degree of unbalance of PCC point voltage obviously reduces, and has reached good compensation effect.Experimental results show that the method compensation network Voltage unbalance effectively.Accompanying drawing 8 and accompanying drawing 9 are respectively the load end three-phase current waveform after cascade STATCOM drops into front and input.Can find out, after dropping into cascade STATCOM, its degree of unbalance also obviously reduces.Verified the validity of the method.
the accompanying drawing explanation:
Fig. 1 positive sequence-negative phase-sequence decoupling zero PWM control block diagram
Fig. 2 compensates the power factor analogous diagram of front A phase
Fig. 3 compensates the power factor analogous diagram of rear A phase
The simulation waveform of system voltage before Fig. 4 cascade STATCOM drops into
The simulation waveform of system voltage after Fig. 5 cascade STATCOM drops into
The experimental waveform of system voltage before Fig. 6 cascade STATCOM drops into
The experimental waveform of system voltage after Fig. 7 cascade STATCOM drops into
The experimental waveform of system power before Fig. 8 cascade STATCOM drops into
The experimental waveform of system power after Fig. 9 cascade STATCOM drops into.
Claims (1)
1. the present invention mainly proposes a kind of new positive sequence-negative phase-sequence decoupling zero PWM control method and solves cascade STATCOM safe and stable operation problem under uneven operating mode, and inquired into its two kinds of mode of operations: reactive power compensation pattern and voltage mode control, specific practice is as follows:
The first step: instruction current obtains
The DC voltage set-point
u dcref with actual value
u dc relatively after PI, obtain the instruction of positive sequence active current
i d+ *,
u abc through T
abc/dq- after coordinate transform, by trapper, obtain the negative phase-sequence active voltage
u d- with the negative phase-sequence reactive voltage
u q- ;
When system voltage is uneven,
u a, b, c -≠ 0,
u d, q- ≠ 0; Control target and be and wish that cascade STATCOM sends the negative sequence voltage with system negative sequence voltage equal and opposite in direction, opposite direction, the negative phase-sequence content that makes system voltage is 0,
u a, b, c- =0, need only
u d, q- =0 gets final product; So utilize
u d- ,
u q- with 0 make difference, after regulating by PI, obtain the instruction of negative phase-sequence active current
i d- *with the negative phase-sequence referenced reactive current
i q- *;
Second step: two kinds of mode of operations
When the positive sequence referenced reactive current
i q+ *reactive power Q and the reactive power set-point Q detected by Instantaneous Power Theory
ref relatively after PI, obtain, when in Figure of description 1, switch is positioned at 1 position, now cascade STATCOM is in the reactive power compensation pattern, take the reactive power of bucking-out system as main, when being usually operated at degree of unbalance and being less than 2%;
When
u abc through T
abc/dq+ after coordinate transform, the positive sequence voltage actual value obtained by the amplitude computing and line voltage set-point
u pCC relatively after PI, obtain
i q+ *, when in Figure of description 1, switch is positioned at 2 position, now cascade STATCOM, in voltage mode control, be take the control system balance of voltage as main, when being usually operated at degree of unbalance and being greater than 2%.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104505844A (en) * | 2015-01-08 | 2015-04-08 | 国网上海市电力公司 | Cascaded STATCOM capacitor voltage balance control method based on active voltage vector reduplication |
| CN104505841A (en) * | 2014-12-03 | 2015-04-08 | 许继电气股份有限公司 | Static synchronous power generator reactive support control method for power grid asymmetric short circuit fault |
| CN104716656A (en) * | 2014-12-31 | 2015-06-17 | 哈尔滨工业大学 | Cascading static synchronous reactive compensator topology with energy exchange unit and control method thereof |
| CN106374474A (en) * | 2015-07-23 | 2017-02-01 | 利思电气（上海）有限公司 | High-voltage active filtering apparatus for inhibiting three-phase imbalance |
| CN109217342A (en) * | 2018-11-17 | 2019-01-15 | 深圳市禾望电气股份有限公司 | Load asymmetric Corrective control method, static reactive generator and storage medium |
| CN109951093A (en) * | 2019-03-13 | 2019-06-28 | 南京理工大学 | A kind of mid-point voltage control system and method based on hybrid parameter |
| CN112838622A (en) * | 2021-03-26 | 2021-05-25 | 云南电网有限责任公司电力科学研究院 | Reactive voltage optimization control method and system for 10kV power supply area |
| CN113300381A (en) * | 2021-03-18 | 2021-08-24 | 北方工业大学 | Control method of chain type STATCOM under unbalanced working condition |
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| CN102255315A (en) * | 2010-05-17 | 2011-11-23 | 江苏方程电力科技有限公司 | Three-phase current balance adjustment system of electric energy adjusting and electricity saving device |
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| CN102255315A (en) * | 2010-05-17 | 2011-11-23 | 江苏方程电力科技有限公司 | Three-phase current balance adjustment system of electric energy adjusting and electricity saving device |
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104505841A (en) * | 2014-12-03 | 2015-04-08 | 许继电气股份有限公司 | Static synchronous power generator reactive support control method for power grid asymmetric short circuit fault |
| CN104716656A (en) * | 2014-12-31 | 2015-06-17 | 哈尔滨工业大学 | Cascading static synchronous reactive compensator topology with energy exchange unit and control method thereof |
| CN104505844A (en) * | 2015-01-08 | 2015-04-08 | 国网上海市电力公司 | Cascaded STATCOM capacitor voltage balance control method based on active voltage vector reduplication |
| CN104505844B (en) * | 2015-01-08 | 2017-01-11 | 国网上海市电力公司 | Cascaded STATCOM capacitor voltage balance control method based on active voltage vector reduplication |
| CN106374474A (en) * | 2015-07-23 | 2017-02-01 | 利思电气（上海）有限公司 | High-voltage active filtering apparatus for inhibiting three-phase imbalance |
| CN109217342A (en) * | 2018-11-17 | 2019-01-15 | 深圳市禾望电气股份有限公司 | Load asymmetric Corrective control method, static reactive generator and storage medium |
| CN109217342B (en) * | 2018-11-17 | 2021-12-07 | 深圳市禾望电气股份有限公司 | Load asymmetry correction control method, static var generator and storage medium |
| CN109951093A (en) * | 2019-03-13 | 2019-06-28 | 南京理工大学 | A kind of mid-point voltage control system and method based on hybrid parameter |
| CN113300381A (en) * | 2021-03-18 | 2021-08-24 | 北方工业大学 | Control method of chain type STATCOM under unbalanced working condition |
| CN113300381B (en) * | 2021-03-18 | 2022-08-30 | 北方工业大学 | Control method of chain type STATCOM under unbalanced working condition |
| CN112838622A (en) * | 2021-03-26 | 2021-05-25 | 云南电网有限责任公司电力科学研究院 | Reactive voltage optimization control method and system for 10kV power supply area |
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Application publication date: 20131211 |