CN102780226B - Direct-current-side voltage control method of cascaded STATCOM based on chopping-control voltage sharing and control circuit - Google Patents
Direct-current-side voltage control method of cascaded STATCOM based on chopping-control voltage sharing and control circuit Download PDFInfo
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Abstract
The invention relates to a direct-current-side voltage control method of a cascaded STATCOM based on chopping-control voltage sharing, and a control circuit. The control circuit comprises a three-phase star-connection multi-level inverter, a two-way chopping control switch and a controller, and is characterized in that the three-phase star-connection inverter is connected with a three-phase power grid through three inlet inductors; each phase of the inverter consists of n pieces of 2H bridge inverter circuit modules serially connected with each other and having an independent direct-current-side capacitor; the direct-current-side capacitors of the n pieces of inverter circuit modules are connected in parallel; and a two-way chopping-control switch is respectively connected with the direct-current-side capacitor of the i<th> inverter circuit module and with the direct-current-side capacitor of the (i-1)<th> inverter circuit module in parallel connection with the i<th> direct-current-side capacitor, wherein i is a natural number from 2 to n. The direct-current-side voltage control method provided by the invention can effectively and reliably solve the key problem limiting the use of the STATCOM with the structure in a high-voltage large-capacity occasion, and can simplify the control program and the design of a regulator, greatly improve the system reliability, and remarkably lower the voltage-sharing control cost, thereby realizing the reliable application of the cascaded STATCOM in high-voltage large-capacitor power equipment.
Description
Technical field
The invention belongs to power quality controlling research field, particularly the DC side voltage control method of mesohigh chain type STATCOM and control circuit.
Background technology
Chain type STATCOM has the significant advantages such as level quantity is many, harmonic content is few, passive device is little, scalability is good; Compensating reactive power is played in electrical power trans mission/distribution system, improve the stability of system voltage, the important function such as the runnability of improvement system, it is the effective means solving mesohigh Large Copacity field power quality problem, it is one of core technology of flexible AC transmitting system (Flexible AC Transmission System, FACTS).
The premium properties of chain type STATCOM and existing system control strategy are all based upon each power model to be had on perfect conforming basis, namely requires that each power model must have identical DC capacitor voltage.But in real system, due to the otherness of the parasitic parameter, operating state etc. of switching device, the absorption of different capacity module needs or the active power sent can be different, therefore the DC voltage with regard to there will be Partial Power module falls comparatively fast, the DC voltage of a part of power model reduces comparatively slow in addition, i.e. DC voltage energy imbalance.Therefore, the control outside plus must ensure DC-side Voltage Stabilization and do not fall, and DC voltage remains equal.
The unbalanced reason of DC voltage is summed up and mainly contains two aspects: one is the inconsistency of power model parameter; Two is inconsistencies of power model operating state, and these two kinds of reasons result in power model consumed energy and the quantity of power consumption is inconsistent.Existing DC voltage control strategy also can be divided into two large classes: the first kind is hardware approach, and basic thought is the energy being carried out the consumption of supply DC bus capacitor by hardware circuit.These class methods typically have: paraller resistanc method, ac bus energy exchange method, DC bus energy exchange method etc., the hardware circuit that these class methods use mainly contains: the combination of PWM rectification circuit, diode rectifier bridge, inverter and isolating transformer, difference between distinct methods is mainly reflected in the path of circuit topology, energy source and energy flow, wherein the most classical method uses phase shift multi winding transformer to add diode rectifier scheme, and it is the main stream approach that current DC capacitor voltage controls.Hardware approach is all pressed, the effect of voltage stabilizing is fine, but cost is high, volume is large, efficiency is low and be not easy to expansion.The difficult design of fractional hardware, production inconvenience, control complexity, but also the power factor step-down of device can be caused, pollute electrical network.
Equations of The Second Kind is software approach, these class methods have employed the thought of closed-loop control, carry out PI adjustment according to the deviation of the DC voltage of power model or the deviation of power, thus obtain the drive singal of each power model, therefore need the DC capacitor voltage gathering all power models.The dependence of these class methods to hardware is less, only need transducer detect voltage, current signal, cost compared with low, volume is little.But the design of pi regulator and debugging complexity.Along with the increase of power model quantity, PI control ring increases thereupon, and making usually needs the PI parameter designing relying on commissioning experience just can complete to complete.And the coupling complexity between each control ring also sharply increases with the increase of module number, system debug difficulty, reliability is very poor, limits the expansion of system.Therefore, the application in actual device is also little.
In addition, the essence of software approach is the pulse duration or the phase angle that have adjusted each power model, namely changes the output pulse signal of CPS-SPWM modulator approach.Change pulse duration or phase angle make CMI output voltage waveforms become asymmetric, introduce more harmonic wave; When power model number is a lot, inconsistency difference is larger time, the harmonic frequency that this method is introduced can be lower, and the adjustable range of phase angle is also less, and therefore the applicable scope of the method is very limited.
Present invention incorporates the advantages such as hardware approach control effects is excellent, software approach is with low cost, what adopt low capacity cuts the chain type STATCOM DC voltage control strategy controlled device and be combined with hierarchical control thought.The program only need to add some costs very low cut control device, coordinate simple control program can realize the stable of each DC capacitor voltage, balanced, eliminate a large amount of high precision test elements and the huge hardware circuit of volume cost, and without the need to numerous complicated, fragile voltage close loop controls, thus simplify control program and design of Regulator, substantially increase reliability and the easy implementation of system, significantly reduce the cost of voltage balance control, shorten product development cycle, thus impel chain type STATCOM to be reliably applied to mesohigh large-capacity power equipment.
Below provide the pertinent literature of retrieval
[1] Liu Wenhua, Song Qiang, Teng Letian. the dc-voltage balance based on the 50MVA STATCOM of chain inverter controls [J]. Proceedings of the CSEE .2004,24 (4): 145-150.
[2] Wei Wenhui. chain type stops the main circuit of synchronous compensator and the research [D] of Dynamic Control Strategy. Tsing-Hua University Ph.D. Dissertation, 2004.
[3] victory is permitted. based on the research [D] of four-quadrant dual H-bridge current transformer cascade connection type Large Copacity DSTATCOM key technology. Southeast China University Ph.D. Dissertation, 2009.
[4] jade-like stone is worn, Chen Jingjing, Gong Li. adopt cascade connection type DSTATCOM decentralized control strategy [J] of many DSP. high voltage technique .2010,36 (11): 2821-2826.
[5] Qiu Yanhui. the research of multiple-level serially connected electric energy quality controller DC side voltage control method. [D] Xi'an Communications University master thesis, 2010.
[6] Liu Zhao, Liu Bangyin, Duan Shanxu. the DC voltage balance of chain static synchronous compensator controls [J]. Proceedings of the CSEE .2009,29 (30): 7-12.
[7]Chen Junling,Yin Zhizhu,Wang Ping et al.Capacitor voltage balancing control ofcascaded multilevel inverter for high-power active power filters[C].Proceedings of the2008IEEE DRPT,2008:1683-1687.
[8]Fujii K,De Doncker R W.A Novel DC-link Voltage Control of PWM-Switched CascadeCell Multi-Level Inverter Applied to STATCOM[C].Proceedings of the 2005IEEE IAS,2005.961-967.
[9]Yanhui Qiu,Yingjie He,Jinjun Liu,Fang Zhuo.A DC Voltage Control Method ofCascaded H-bridge Inverter for Power Quality Conditioner[C].ISIE 2010,Bari.
Yingjie He,Yanhui Qiu,Jinjun Liu,Fang Zhuo.A Comprenhensive Study of VoltageBalancing Problem of Cascaded H-bridge Inverter for Power Quality Conditioner[C].Proc.ofIEEE IPEC2010.
Summary of the invention
The object of the present invention is to provide and a kind ofly all press the chain type STATCOM DC capacitor voltage control strategy with hierarchical control thought compound use based on cutting control.What the program only needed to add some low capacities cuts control device, coordinate simple control program can realize the stable, balanced of each DC capacitor voltage, thus save complicated voltage close loop control completely, the hardware cost of remarkable reduction Pressure and Control, reliably control each power model DC capacitor voltage of chain type STATCOM, make it stable, balanced, guarantee that system works efficiently, reliably under high-voltage large-capacity power utilization environment.
Set forth from topology design and control realization two aspect below:
1) topology design:
Three-phase chain structure multi-electrical level inverter, is connected with three phase network by three inlet wire inductance; Inverter is respectively made up of N number of 2H bridge inverter circuit block coupled in series having independent direct current lateral capacitance, and module number N determines according to line voltage grade, generally gets N > e
m/ u
dc, wherein e
mfor the amplitude of line voltage, u
dcfor the DC capacitor voltage desired value of each power model;
Every use that 2 × (N-1) is individual cuts control device mutually, namely two-wayly control switch is cut, for the DC bus capacitor between control connection power model, thus form public DC bus, unbalanced energy is flowed freely and the unbalanced power of reasonable distribution by DC bus, finally makes the DC capacitor voltage of each module all reach poised state.
2) control realization:
A) the threephase load electric current of target compensation is detected by current sensor;
B) in control circuit board, according to instantaneous reactive power theory, coordinate transform is carried out to the load current detected, obtain each phase current composition---idle, harmonic wave, the imbalance etc. that need to compensate;
C) obtained the phase information of three-phase power grid voltage by phase-locked link computing, and its and instruction value is multiplied obtains fundamental active current composition, be i.e. overall active power controller algorithm;
D) using superimposed as final control command for above current component b) and c) obtained, the output current of three-phase inverter is controlled; Concrete implementation method detects the output current of three-phase linked storage structure, and difference is done in it and the control command of corresponding each phase, and utilize phase shift carrier modulating method to produce CPS-SPWM signal, in order to drive the switching tube IGBT of each power model after being regulated by PI;
E) drive singal of bidirection switching device is generated by the logic of main switch, to determine whether the electric capacity of each power model is parallel to DC bus, thus carry out energy exchange by common DC bus, unbalanced energy is redistributed between the DC bus capacitor of each power model, until capacitor voltage balance.
Described step e) described in the balance of voltage refer to that the voltage of each DC bus capacitor is substantially equal or voltage deviation Δ u is within the limits prescribed between two.
The invention has the beneficial effects as follows:
The present invention cuts control device by more additional low capacities, be aided with simple control program, just can realize redistributing the energy of each DC bus capacitor of chain type STATCOM, its capacitance voltage is made to keep stable and balanced, effectively and reliably solve the key issue limiting this structure STATCOM and use in high-voltage large-capacity occasion, and eliminate a large amount of high precision test elements, and it is complicated, fragile voltage close loop controls, thus simplify control program and design of Regulator, substantially increase the reliability of system, significantly reduce the cost of Pressure and Control, thus impel chain type STATCOM to be reliably applied to mesohigh large-capacity power equipment.In addition, by building chain type STATCOM simulation model, simulating, verifying having been carried out to this control program, having confirmed the validity and reliability of the program.Although only built the cascaded structure of 5 modules in emulation, in real system, the method easily extensible is to the series connection of operational blocks which partition system, thus is applied in more high-tension power utilization environment by this system, therefore has actual engineer applied and is worth.
Accompanying drawing explanation
The structural representation of Fig. 1 chain type STATCOM.
The systematic control algorithm block diagram of Fig. 2 chain type STATCOM.
The overall active power controller algorithm block diagram of Fig. 3.
Fig. 4 cuts the annexation figure between control device and power model.
Fig. 5 circulation working mode figure.
Fig. 6 all presses working mode figure.
The generation method of Fig. 7 switching tube drive singal.
Fig. 8 is without DC voltage waveform during DC voltage control.
Fig. 9 (a) apply overall active power controller and no-voltage Balance route time the Equivalent DC side voltage waveform of CMI.
Fig. 9 (b) apply overall active power controller and no-voltage Balance route time the DC voltage waveform of each power model.
Figure 10 adopts DC capacitor voltage waveform when cutting control method for equalizing voltage.
Figure 11 cuts the waveform of the equalizing current flow through in control device.
The compensation effect of the chain type STATCOM that Figure 12 five power model series connection are formed.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in detail.
The structure of chain type STATCOM as shown in Figure 1, by formations such as electrical network, reactive load, connection inductance and linked storage structure (Cascaded Multilevel Inverter, CMI).CMI is composed in series by N number of power model (inverter circuit module).The present invention is described with Y-connection structure, and the control method that triangle connects can be analogized.Every phase CMI is by being parallel to the points of common connection (Point of Common Coupling, PCC) of system after being connected in series inductance.Forming the power model of CMI is a complete single-phase inverter, comprises independently power switch pipe, DC side power supply, drive circuit, testing circuit, protection and control circuit etc.Power model shown in Fig. 1 is single-phase 2H bridge inverter, is a kind of power model the most frequently used at present.
At present, the widely used modulation strategy of chain type STATCOM is carrier phase SPWM Technique CPS-SPWM (Carrier Phase-Shifted SPWM).Widely used system control strategy is feed forward decoupling control algorithm, as shown in Figure 2.Referenced reactive current i
lqby obtaining load current sampling and idle detection algorithm; Active current instruction i
ldby detecting power model DC voltage and the acquisition of active current control algolithm; Detect voltage on line side, device output current, and the feed-forward voltage u that coordinate transform obtains under synchronous rotating frame is carried out to it
sd, u
sqand feedback current i
cd, e
cq, namely above-mentioned physical quantity obtains the command voltage u of auto levelizer through Uncoupling Control Based
cd, u
cq, command voltage obtains final modulation signal through park inverse transformation, then compares with phase shift triangular carrier and just obtain final drive singal.
Method disclosed in patent of the present invention have employed hierarchical control thought and cuts control and all press the thinking combined, and is divided into two levels generally: ground floor, by the total active power of software approach control device, makes CMI Equivalent DC side voltage stabilization be command value; The second layer forms common DC bus by cutting control device, and determines whether each power model is parallel to DC bus and carries out energy exchange by the operating state of main circuit, thus realizes the electric voltage equalization between power model.The method combines soft and hardware method advantage separately, has avoided both shortcomings, is a kind of reliable, effective practical method.
1, overall active power controller
Actual chain type STATCOM is not desirable reacance generator.In the course of the work, because the actions such as the cut-offfing of switching tube, conducting need to consume active power, therefore the DC voltage of power model will little by little reduce, and the speed reduced depends on the size of the active power that power model consumes, that is the decrease of DC voltage reflects the active power that power model needs.Therefore, the summation of DC voltage reduction of each module and the total active power positive correlation required for system.Namely overall active power (fundamental positive sequence active power) control algolithm is obtained, as shown in Figure 3 by negative feedback thought.U in figure
refrepresentation module DC voltage set-point; u
dc_ai, u
dc_bi, u
dc_cirepresent the DC voltage value of i-th power model in actual A, B, C three-phase detected respectively.Utilize the method just can make up the active power of system works institute loss in time to the active power needed for power model injection.
Due to the inconsistency of power model, the DC voltage rate of descent of disparate modules is also inconsistent; In like manner every active power required mutually also may be inconsistent.Now, the control of active power should comprise two levels: the alternate balance of overall active power controller and active power controls.The emphasis of this patent is the voltage balance control strategy between power model, therefore supposes that the situation of each phase is consistent, so do not consider alternate Balance route.
2, the voltage balance control between module
Total active power enough time, be exactly remaining work makes unbalanced energy reasonable distribution between each power model.The method that this patent proposes is exactly: form common DC bus by multiple control device of cutting, determine whether the DC bus capacitor of each power model is parallel to DC bus and carries out energy exchange by the operating state of main circuit, thus realize the electric voltage equalization between power model.
Cut control device and main circuit power model between annexation as shown in Figure 4.Control device is cut by the DC bus capacitor C of power model by two
1, C
2forward be together in parallel, unbalanced active power is directly flowed freely on the DC bus of each power model, thus realize redistributing and the balance of voltage of energy, as shown in the shadow region in Fig. 4.
S
1, S
2there are four kinds of states: 00,01,10,11.Suppose that the DC voltage of power model is U
dc, then corresponding output voltage is respectively: 0 ,-U
dc,+U
dc, 0.In like manner, be connected to the power model cutting control device two ends, they may have 16 kinds of assembled state.
In Fig. 5, S
1, S
2, S
3, S
4state be 1010, output voltage is respectively+U
dc,+U
dc.Now, switching tube
(in same brachium pontis, the switching logic of upper and lower two switching tubes is contrary, namely
be with S
2the switching tube that same brachium pontis breaker in middle logic is contrary), T
2, S
3and electric capacity C
1constitute a short-circuited conducting sleeve circulation flow path, switching tube
t
3, S
3and electric capacity C
2constitute an other short-circuited conducting sleeve circulation flow path, the two is forward in parallel.Therefore, the switch transistor T of control device is cut
2, T
3must turn off, its assembled state is 00; And T
1, T
4open or turn off the work of main circuit and equalizer circuit is not all affected, its state can be any one in 00,01,10,11, is in free state.For simplifying logical expression, therefore free state is unified assignment 00.Therefore T
1, T
2, T
3, T
4state be 0000.In like manner, S is worked as
1, S
2, S
3, S
4state when being respectively 1010,1011,1100,1101,0010,0011,0100,0101, just there are two short-circuited conducting sleeve circulation flow paths forward in parallel, cutting control device and should be operated in isolation, T now
1, T
2, T
3, T
4assembled state be 0000.
In Fig. 6, S
1, S
2, S
3, S
4state be 1000, output voltage is respectively+U
dc, 0, now there is not short-circuited conducting sleeve circulation flow path, cut control device and be operated in equal pressure condition, the imbalance power of power model DC bus capacitor flows freely until the balance of voltage, i.e. now T
1, T
2, T
3, T
4state be 1111.In like manner, S is worked as
1, S
2, S
3, S
4state when being respectively 1000,1001,1110,1111,0000,0001,0110,0111, there is not short-circuited conducting sleeve circulation flow path, cut control device and be operated in equal pressure condition, T
1, T
2, T
3, T
4state be 1111.
The operation principle of this topology can be summarized as follows: the switching tube 1, cutting control device is in identical logic state simultaneously, namely opens simultaneously, turns off simultaneously; 2, the logic state cutting control device is only relevant with the switching logic of close two power models, and has nothing to do with the size and Orientation of power current, and the switching frequency cutting control device is the twice of main circuit switch frequency; Cut control device when 3, there is short-circuited conducting sleeve circulation flow path and can not be operated in equal pressure condition, cut time control device is operated in equal pressure condition and can not there is short-circuited conducting sleeve circulation flow path; 4, time the switching logic of a upper right brachium pontis of power model is contrary with the switching logic of the left brachium pontis of next power model, just necessarily there is short-circuited conducting sleeve circulation flow path; If 5 have short-circuited conducting sleeve circulation flow path to exist, just necessarily have two short-circuited conducting sleeve circulation flow paths to exist, and these two short-circuited conducting sleeve circulation flow paths are forward in parallel simultaneously; 6, cut control device when being operated in equal pressure condition, forward grading ring circulation flow path and reverse grading ring circulation flow path exist but asynchronously work simultaneously.
T can be obtained according to above-mentioned analysis
1, T
2, T
3, T
4with S
1, S
2, S
3, S
4between switching logic relation
T
1＝T
2＝T
3＝T
4＝S
2⊙S
3
Although the method tells about for the electric voltage equalization of two power models, the system formed to multiple block coupled in series can be analogized.Make to cut control switch in parallel by two-way between the DC bus capacitor of N number of inverter circuit module, 1st and 2 electric capacity two ends connect two-way control switch of cutting respectively and (connect one between the positive pole of the positive pole of the 1st DC bus capacitor and the 2nd DC bus capacitor and two-wayly cuts control switch, between the negative pole of the negative pole of the 1st DC bus capacitor and the 2nd DC bus capacitor, connection one is two-way cuts control switch, thus it is in parallel in the same way to realize between the 1st DC bus capacitor with the 2nd DC bus capacitor), 2nd to be connected respectively with 3 electric capacity two ends and two-wayly to cut control switch, 3rd to be connected respectively with 4 electric capacity two ends and two-wayly to cut control switch, by that analogy, have that 2 (N-1) is individual two-wayly cuts control switch, thus form public DC bus.
Two-way the cutting that in like manner can obtain between the DC bus capacitor of i-th inverter circuit module and the DC bus capacitor of the i-th-1 inverter circuit module controls switch Q
i-1, with i-th inverter circuit module in switching tube S
2i-1, S
2iwith the switching tube S in the i-th-1 inverter circuit module
2i-3, S
2i-2between switching logic relation:
Q
i-1＝S
2i-2⊙S
2i-1
According to the rule of above formula and CPS-SPWM, the generation method of all switching tube drive singal can be drawn, as shown in Figure 7.
Obviously, the steady-state error of DC voltage is less, and namely control effects is better, and grading ring stream is also less, two-way cut control switch capacity also less, hardware cost and power loss are also less.Under the guarantee of cutting control Pressure and Control algorithm, after system enters stable state, the voltage of each power model can keep stablizing, balanced, and the energy loss in pressure equalizing is approximately zero.The use of the method can not cause too many energy loss, not the whole efficiency of influential system.It should be noted that: any pressure equalizing control method all can cause energy loss, this is determined by capacitance voltage disequilibrium.
In addition, method disclosed in this patent only needs the DC voltage detecting some power models can meet the requirement of software algorithm, thus significantly minimizing and DC voltage measure the required hardware device such as relevant input, conditioning, analysis, calculating and controller resource, are therefore all pressed into and are originally reduced.
A kind of chain type STATCOM DC side voltage control method based on cutting control and all pressing is given in the present invention.And utilize the simulink in MATLAB to carry out simulating, verifying to this control method.CMI in simulation model have employed 5 power model series connection.Fig. 8 simulates the adverse effect not adding DC voltage control and can cause; Fig. 9 simulates effect when only having overall active power controller, and energy imbalance has appearred in DC voltage; Figure 10 gives the effect of the DC voltage control under this patent method, and the DC voltage of power model enters stable state rapidly, and steady-state error is almost nil; Figure 11 gives the equalizing current flowing through because of electric voltage equalization process and cut control device, its peak value is no more than 1.5A, mean value is almost 0, therefore cut voltage that control device needs to bear, electric current is very little, namely the capacity cutting control device is very little, substantially the not volume of influential system and cost, and all crushing consumption is very little, can not the whole efficiency of influential system.Figure 12 gives the compensation effect of chain type STATCOM under new method.Simulation result shows: achieve the stable with balanced of chain type STATCOM DC voltage based on cutting the control method that control all presses, can safeguards system long-time safe, stablize, work efficiently.Traditional hardware pressure equalizing control method can be substituted completely and control effects is constant, thus achieve object that is cost-saving, that raise the efficiency, there is very important practical engineering value.
Claims (5)
1., based on the chain type STATCOM DC side voltage control method cut control and all press, it is characterized in that, comprise the steps:
1) topology design:
Three-phase Y-connection multi-electrical level inverter, is connected with three phase network by three inlet wire inductance; Inverter is respectively made up of N number of 2H bridge inverter circuit block coupled in series having independent direct current lateral capacitance;
The DC bus capacitor of N number of inverter circuit module is in parallel: between the positive pole of the positive pole of the DC bus capacitor of i-th inverter circuit module and the DC bus capacitor of the i-th-1 inverter circuit module, connection one is two-way cuts control switch, between the negative pole of the negative pole of the DC bus capacitor of i-th inverter circuit module and the DC bus capacitor of the i-th-1 inverter circuit module, connection one is two-way cuts control switch, thus it is forward in parallel to realize between the DC bus capacitor of i-th inverter circuit module and the DC bus capacitor of the i-th-1 inverter circuit module, wherein i=2,., N; Every use that 2 × (N-1) is individual two-wayly cuts control switch mutually altogether, thus form public DC bus;
Be provided with two parallel connections in i-th inverter circuit module and separate brachium pontis, each brachium pontis is divided into brachium pontis and lower brachium pontis, and the upper brachium pontis wherein near capacitive side is provided with switching tube S
2i-1, on another, brachium pontis is provided with switching tube S
2i; Upper brachium pontis in like manner near capacitive side in the i-th-1 inverter circuit module is provided with switching tube S
2i-3, on another, brachium pontis is provided with switching tube S
2i-2;
2) control realization:
A) the threephase load electric current of target compensation is detected by current sensor;
B) coordinate transform is carried out to the load current detected, obtain each phase current composition needing to compensate;
C) obtained the phase information of three-phase power grid voltage by phase-locked link computing, and its and instruction value is multiplied obtains fundamental active current composition, be i.e. overall active power controller algorithm;
D) using superimposed as final control command for above current component b) and c) obtained, the output current of three-phase inverter is controlled;
E) the two-way drive singal cutting control switch is generated by the logic of the switching tube of inverter circuit module, with determine every mutually in the electric capacity of each power model whether be parallel to described public DC bus, thus carry out energy exchange by described public DC bus, unbalanced energy is redistributed between the DC bus capacitor of each power model, until capacitor voltage balance;
Described steps d) in control the output current implementation method of three-phase inverter and be: detect three-phase inverter output current, and difference is done in it and the control command of corresponding each phase, and utilize the modulator approach of phase shift carrier wave to produce corresponding CPS-SPWM signal after being regulated by PI, in order to drive the switching tube of each power model;
Described step e) in: two-way the cutting between the DC bus capacitor of i-th inverter circuit module and the DC bus capacitor of the i-th-1 inverter circuit module controls switch Q
i-1, with i-th inverter circuit module in switching tube S
2i-1, S
2iwith the switching tube S in the i-th-1 inverter circuit module
2i-3, S
2i-2between switching logic close be: Q
i-1=S
2i-2⊙ S
2i-1.
2. method according to claim 1, is characterized in that: described step e) described in the balance of voltage refer to that the voltage of each DC bus capacitor is substantially equal or voltage deviation Δ u is within the limits prescribed between two.
3. method according to claim 1, is characterized in that: N determines according to line voltage grade, gets N > em/udc; Wherein em is the amplitude of line voltage, and udc is the DC capacitor voltage desired value of each power model.
4. method according to claim 1, is characterized in that: each phase current composition comprises idle, harmonic wave, uneven composition.
5. chain type STATCOM DC voltage control circuit is all pressed in the control of cutting based on method described in claim 1, comprises three-phase Y-connection multi-electrical level inverter, two-way cutting controls switch, controller; It is characterized in that: three-phase Y-connection multi-electrical level inverter is connected with three phase network by three inlet wire inductance; Inverter is respectively made up of N number of 2H bridge inverter circuit block coupled in series having independent direct current lateral capacitance; The DC bus capacitor of N number of inverter circuit module is in parallel: between the positive pole of the positive pole of the DC bus capacitor of i-th inverter circuit module and the DC bus capacitor of the i-th-1 inverter circuit module, connection one is two-way cuts control switch, between the negative pole of the negative pole of the DC bus capacitor of i-th inverter circuit module and the DC bus capacitor of the i-th-1 inverter circuit module, connection one is two-way cuts control switch, thus it is forward in parallel to realize between the DC bus capacitor of i-th inverter circuit module and the DC bus capacitor of the i-th-1 inverter circuit module, wherein i=2,., N; Every use that 2 × (N-1) is individual two-wayly cuts control switch mutually altogether, thus form public DC bus; Be provided with two parallel connections in i-th inverter circuit module and separate brachium pontis, each brachium pontis is divided into brachium pontis and lower brachium pontis, and the upper brachium pontis wherein near capacitive side is provided with switching tube S
2i-1, on another, brachium pontis is provided with switching tube S
2i; Upper brachium pontis in like manner near capacitive side in the i-th-1 inverter circuit module is provided with switching tube S
2i-3, on another, brachium pontis is provided with switching tube S
2i-2; To control in i-th inverter circuit module in DC bus capacitor and the i-th-1 inverter circuit module between DC bus capacitor two-way cuts control switch Q for controller
i-1, with i-th inverter circuit module in switching tube S
2i-1, S
2iwith the switching tube S in the i-th-1 inverter circuit module
2i-3, S
2i-2between switching logic close be: Q
i-1=S
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| CN103280820B (en) * | 2013-06-16 | 2015-01-14 | 中国科学院电工研究所 | Direct current side capacitor voltage balance control method of chained static synchronous compensator |
| CN103401462B (en) * | 2013-07-09 | 2016-02-10 | 上海交通大学 | Based on the single-phase chain static synchronous compensator of three level H bridge cascade |
| CN106451496B (en) * | 2016-10-21 | 2019-04-12 | 国网新疆电力有限公司电力科学研究院 | A kind of quick suppressing method of large-scale wind powered generation syst network voltage low-frequency oscillation |
| CN107592010A (en) * | 2017-08-05 | 2018-01-16 | 天津大学 | Modular multilevel dynamic switching DC DC transformers |
| CN107911023A (en) * | 2017-11-07 | 2018-04-13 | 天津大学 | The more level dynamic switching DC DC transformers of cascade moduleization |
| CN107910876B (en) * | 2017-11-23 | 2020-09-01 | 广东电网有限责任公司电力科学研究院 | Outer loop voltage control method and device based on chain type STATCOM |
| CN108199582A (en) * | 2017-12-28 | 2018-06-22 | 天津大学 | The more level DC-DC transformers of multi-port modular |
| CN108233394A (en) * | 2018-02-10 | 2018-06-29 | 国家电网公司 | A kind of capacitive coupling voltage balancing control method suitable for Y type chain types STATCOM |
| CN111342687B (en) * | 2018-12-19 | 2021-10-01 | 南京南瑞继保工程技术有限公司 | Cascaded full-bridge multi-level converter topology with self-voltage-sharing characteristic and control method |
| CN111342690B (en) * | 2020-03-13 | 2021-09-03 | 南京理工大学 | Modulation method of split capacitor power unit multilevel converter |
| CN111478608B (en) * | 2020-04-07 | 2021-11-09 | 南京理工大学 | Circuit topology structure for automatically balancing direct-current side voltage and control method thereof |
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| CN102136729A (en) * | 2011-02-22 | 2011-07-27 | 西安交通大学 | Series multi-level SVG (scalable vector graphics) topological structure based on phase shifting multiple winding rectifier transformer and control method thereof |
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| 基于飞渡电容的级联多电平STATGSM直流侧电压控制方法研究;孙乐等;《大功率变流技术》;20110831(第4期);第26-31页 * |
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