CN108281973A - A kind of MMC nonlinear control methods based on sliding formwork control - Google Patents
A kind of MMC nonlinear control methods based on sliding formwork control Download PDFInfo
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- CN108281973A CN108281973A CN201711306945.6A CN201711306945A CN108281973A CN 108281973 A CN108281973 A CN 108281973A CN 201711306945 A CN201711306945 A CN 201711306945A CN 108281973 A CN108281973 A CN 108281973A
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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
-
- 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
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
- H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
-
- 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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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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
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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
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
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Abstract
The present invention relates to a kind of MMC (Modular Multilevel Converter, MMC) nonlinear control method based on sliding formwork control, this approach includes the following steps：Become three-phase voltage current signal of changing commanders using 3s/2s to be converted under two-phase stationary coordinate system；Fundamental positive sequence extraction is carried out, active power is carried out using fundamental positive sequence and reactive power reference qref calculates；It is poor that active power reference value and active power instantaneous value are made, and it is poor that reactive power reference qref and reactive power instantaneous value are made, and difference is inputted to sliding formwork control module respectively；It is inputted as phase shift carrier modulation after being summarized using sliding formwork control module output valve and loop current suppression controller output valve, direct voltage output value, MMC bridge arm controls is carried out using phase shift carrier modulation output signal.Compared with prior art, the present invention has many advantages, such as that there is control method better rapidity and stability, control system can ensure ac-side current without negative sequence component and power without secondary fluctuation.
Description
Technical field
The present invention relates to the controls of modular multi-level converter (Modular Multilevel Converter, MMC)
Technology, more particularly, to a kind of MMC nonlinear control methods based on sliding formwork control.
Background technology
Compared to traditional D.C. high voltage transmission (High Voltage Direct Current Transmission,
HVDC) system, had based on the half controls device system such as thyristor can be achieved active power and reactive power decoupling control, can be to
Passive network power supply, inverter side the advantages that not will produce commutation failure, but it there is also some technological deficiencies, it must rely on and hand over
Busbar voltage is flowed to realize its shutdown, and commutation failure easily occurs when power system capacity is inadequate.In recent years, it is based on modular multilevel
The HVDC systems of transverter (MMC) have well solved this problem, it can realize automatic shutoff not against ac bus,
The waveform quality of its output voltage is high, and have many advantages, such as modular manufacturing facilitate, troubleshooting capability it is strong, thus it by
Gradually instead of two traditional level converters.
When unbalanced source voltage, if do not controlled current transformer, for the higher distributed energy of permeability
Will be extensive out of service, namely no longer there is the ability for continuing to be incorporated into the power networks.Therefore, in the MMC of unbalanced electric grid voltage
The research of control strategy is very necessary.For this purpose, there is document to propose direct Power Control strategy, control thought is two
The mathematical model that MMC-HVDC is established under phase rest frame carries out power benefit according to the characteristic of unbalanced source voltage MMC
It repays, but its calculating power back-off process is complex；There is document to propose passive control method, improved no phase-locked loop control respectively
Method processed, but they all do not consider the problems of that circulation controller fluctuates DC voltage and inhibit；There is document to propose that one kind is based on
The inner ring of MMC discrete models controls, but its to establish discrete model process relatively complicated；There is the method that document uses current control,
But it is theoretical also not overripened；It due to the strong robustness of sliding formwork control, and is easily achieved, responds quickly, thus have document for general
Logical grid-connected converter, it is proposed that sliding-mode control under conditions of unbalanced source voltage, but this method is applied not yet
Into MMC.
Invention content
It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and provide one kind being based on sliding formwork control
MMC nonlinear control methods.
The purpose of the present invention can be achieved through the following technical solutions：
A kind of MMC nonlinear control methods based on sliding formwork control, the method include the following steps：
S1, three-phase voltage current signal of being changed commanders using 3s/2s changes are converted under two-phase stationary coordinate system；
S2, fundamental positive sequence extraction is carried out, active power and reactive power reference qref is carried out using fundamental positive sequence
It calculates；
S3, active power reference value and active power instantaneous value are made it is poor, by reactive power reference qref and reactive power wink
It is poor that duration is made, and difference is inputted to sliding formwork control module respectively；
S4, make after being summarized with sliding formwork control module output valve and loop current suppression controller output valve, direct voltage output value
It is inputted for phase shift carrier modulation, MMC bridge arm controls is carried out using phase shift carrier modulation output signal.
Preferably, sliding formwork control module chooses active deviation and idle deviation and is used as sliding-mode surface for 0 in the step S3：
Wherein, SP(S)、SQ(S) it is active and reactive power sliding-mode surface；Pref、QrefFor active power and reactive power
Reference value；P, Q is respectively the instantaneous value of active power and reactive power.
Preferably, sliding-mode surface time computational methods are reached：
Wherein, TP、TQThe time of active power and reactive power sliding-mode surface is reached for original state；K11、K12、K21、K22For
Adjustment factor；SP0、SQ0For the initial value of active power and reactive power.
Preferably, active power instantaneous value is calculated by two-phase voltage and biphase current in the step S3, idle work(
Rate instantaneous value is calculated by two-phase voltage and biphase current, and calculation formula is：
Wherein, P, Q are respectively active power instantaneous value, reactive power instantaneous value；usα、usβ、isα、isβRespectively exchange side
The component of three-phase voltage and electric current under two-phase stationary coordinate system.
Preferably, active power reference value and reactive power reference qref control mesh according to two respectively in the step S3
Mark carries out respective value setting, and described two control targes include：
A. ac-side current is without negative sequence componentActive power and reactive power reference qref under the target
For：
Wherein, Pref、QrefThe respectively reference value of active power and reactive power, usα、usβRespectively three-phase voltage exchanges
Amount is in two-phase stationary coordinate system component；Respectively positive sequence of the three-phase current of ac under two-phase stationary coordinate system point
Amount；
B. active power and reactive power are without fluctuation, and active power and reactive power reference qref are under the target：
Pref=Pcom、Qref=Qcom
In formula：Pref、QrefThe respectively reference value of active power and reactive power, Pcom、QcomRespectively active power and
Reactive power given value.
Preferably, the signal for phase shift carrier modulation being input in the step S4 is：
Wherein, ujp、ujnFor the voltage of upper underarm；udcFor DC voltage；vjFor the output voltage of exchange side；ucirjTo follow
The pressure drop that circular current generates.
Preferably, the loop current suppression controller filters out low frequency wave first with low-pass filter, then to filtered
Two frequency-doubled signals afterwards carry out PR controls, inhibit two frequencys multiplication of DC voltage or electric current.
Preferably, loop current suppression controller input terminal connects DC current signal output end in the step S4.
Compared with prior art, the present invention has the following advantages：
1, control method has better rapidity and stability：Sliding formwork control is applied in MMC, is become according to sliding formwork and is tied
Structure is theoretical, and Sliding mode variable structure control is used for the MMC under unbalanced electric grid voltage, compares more traditional control method, it
There are better rapidity and stability, control effect is more preferably；
2, control system can ensure ac-side current without negative sequence component and power without secondary fluctuation.
Description of the drawings
Fig. 1 is MMC topology diagrams；
Fig. 2 is submodule (SM) composition schematic diagram；
Fig. 3 is the overall structure block diagram of MMC control systems；
Fig. 4 is 1 time PI control ac-side current oscillogram of control targe；
Fig. 5 is 1 time PI control exchange side active power oscillogram of control targe；
Fig. 6 is 1 time PI control exchange side active power oscillogram of control targe；
Fig. 7 is the ac-side current oscillogram of 1 time the method for the present invention of control targe；
Fig. 8 is the exchange side active power oscillogram of 1 time the method for the present invention of control targe；
Fig. 9 is the exchange side reactive power oscillogram of 1 time the method for the present invention of control targe；
Figure 10 is the A phase current spectrograms of control targe 1 time PI controls；
The A phase current spectrograms of 1 time the method for the present invention of Figure 11 control targes；
Figure 12 is 1 time PI control ac-side current oscillogram of control targe；
Figure 13 is 1 time PI control exchange side active power oscillogram of control targe；
Figure 14 is 1 time PI control exchange side active power oscillogram of control targe；
Figure 15 is the ac-side current oscillogram of 1 time the method for the present invention of control targe；
Figure 16 is the exchange side active power oscillogram of 1 time the method for the present invention of control targe；
Figure 17 is the exchange side reactive power oscillogram of 1 time the method for the present invention of control targe；
Figure 18 is the current waveform figure under object of experiment 1；
Figure 19 is the power waveform figure under target 1；
Figure 20 is the current waveform figure under target 2；
Figure 21 is the power waveform figure under target 2.
Specific implementation mode
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation describes, it is clear that described embodiment is a part of the embodiment of the present invention, rather than whole embodiments.Based on this hair
Embodiment in bright, the every other reality that those of ordinary skill in the art are obtained without making creative work
Example is applied, the scope of protection of the invention should be all belonged to.
Embodiment
The present invention relates to a kind of strategies of nonlinear Control-Sliding mode variable structure control under unbalanced electric grid voltage, although sliding
Mould control has the advantages that many, but there is presently no documents to apply to sliding formwork control on MMC.
The present invention is for this specific current transformer of MMC, it is proposed that a kind of sliding moding structure based on direct Power Control
Control strategy.It is controlled it using Sliding Mode Controller, ac-side current can be ensured without negative sequence component and power
Without secondary fluctuation.
Technical scheme of the present invention：A kind of control strategy for the MMC under unbalanced electric grid voltage, it is mainly utilized
Sliding mode variable structure control sets up mathematical model to the MMC under unbalanced electric grid voltage, formulates its sliding mode control strategy, make it
Ac-side current non-negative sequence current, power is without secondary fluctuation.Specifically comprise the following steps：
Step S1：According to the topological structure of the MMC of Fig. 1, MMC is made of upper and lower 6 bridge arms, and each bridge arm has identical
Submodule (SM) structure of several Fig. 2, MMC exchange side and the mathematical model of DC side can be obtained by Fig. 1：
In formula：usa、usb、uscFor a, b, c three-phase output voltage of exchange side；va、vb、vcFor transverter side three-phase alternating current
Pressure；L0、R0Reactance, resistance for exchange side；isa、isb、iscFor the three-phase current of exchange side；ujp、ujnFor the electricity of the upper and lower arm of j phases
Pressure；icirjFor the alternate circulation of j；LjFor the inductance of j phase bridge arms.
Step S2：According to coordinate transform theory, the voltage equation of exchange side is transformed under α β two-phase stationary coordinate systems, it can
To obtain：
Wherein, vα、vβRespectively exchange side reference voltage is in α β coordinate system components；Usα、UsβIt is voltage in the static seat of two-phase
The lower component of mark system.
And when unbalanced source voltage, the voltage and current under two-phase stationary coordinate system can be decomposed into：
In formula：Usαβ、IsαβRespectively exchange side three-phase voltage current component is in α β coordinate system components；Respectively
usjIn the positive and negative sequence component of α β coordinate systems；Respectively isjPositive and negative sequence component under α β coordinate systems.
According to instantaneous power theory, the instantaneous power of MMC exchange side can be expressed as：
In formula：P, Q is respectively active power, reactive power；usα、usβRespectively three-phase voltage of ac is in α β coordinate systems
Component；isα、isβRespectively three-phase current of ac is in α β coordinate system components.
Step S3：Instantaneous power is write as to the form of matrix：
In formula：P0For active power DC quantity, PC2For two harmonics, the P of active power cosine componentS2For active power
Two harmonics, the Q of sinusoidal component0For reactive power DC quantity, QC2For two harmonics, the Q of reactive power cosine componentS2For
Two harmonics of reactive power sinusoidal component.
Derivation is carried out to the instantaneous power under the conditions of unbalanced source voltage, obtains expression formula：
Step S4：Expression formula after instantaneous power derivation that step 3 obtains is organized into
Dx/dt=Ax+Bu+F
Wherein
In formula：ω1For the public angular frequency of power grid；usFor exchange side instantaneous voltage.
According to sliding mode theory, active deviation and idle deviation is selected to be used as sliding-mode surface for 0, namely：
In formula：SP(S)、SQ(S) it is active and reactive power sliding-mode surface；Pref、QrefFor active power and reactive power
Reference value；P, Q is actual active power and reactive power value.
In order to eliminate the shake generated in sliding-mode surface handoff procedure, sign function is replaced using saturation function, is obtained defeated
The exchange side reference voltage gone out is：
In formula：vα、vβRespectively exchange side reference voltage is in α β coordinate system components；A1、A2Respectively after instantaneous power derivation
A coefficients respectively in the expression formula of α β coordinate systems；X1、X2X coefficients respectively after instantaneous power derivation are respectively in α β coordinate systems
Expression formula；F1、F2F coefficients respectively after instantaneous power derivation are respectively in the expression formula of α β coordinate systems；K11、K12、K21、K22For
Adjustment factor；sat(SP)、sat(SQ) it is respectively SP、SQSaturation function.
Step S5：Convergence and determination of stability to obtained sliding formwork control, the stability of the control strategy and convergence
Property can be judged by Liapunov (Lyapunov) stability criteria.Lyapunov functions, which can be constructed, is：
Its derivation is obtained
The Lyapunov functions of selection reduce in increase at any time, until be retracted to 0 namely system can converge on
Change section.By initial value SP0、SQ0Reaching the time of sliding-mode surface can obtain：
Wherein, TP、TQThe time of active power and reactive power sliding-mode surface is reached for original state；SP0、SQ0For wattful power
The initial value of rate and reactive power.
From the above equation, we can see that system can converge to sliding surface within a certain period of time, and by reducing K11、K21Or increase K12、K22
It can accelerate approach procedure.
Step S6：According to the MMC problems under non-equilibrium state, control targe can be set as to two：(1) it exchanges
Side electric current is without negative sequence component(2) power is without fluctuation.And according to artificial given active power and reactive power
Value Pcom、QcomWith step 3 instantaneous power expression formula, and then obtain：
The reference value of active power and reactive power under target (1) is：
Wherein, Pref、QrefThe respectively reference value of active power and reactive power, usα、usβRespectively three-phase voltage exchanges
Amount is in two-phase stationary coordinate system component；Respectively positive sequence of the three-phase current of ac under two-phase stationary coordinate system point
Amount；
The reference value of active power and reactive power under target (2) is：
Pref=Pcom、Qref=Qcom
In formula：Pref、QrefThe respectively reference value of active power and reactive power, Pcom、QcomRespectively active power and
Reactive power given value.
Step S7：When imbalance fault occurs for network voltage, DC voltage (electric current) can also fluctuate, Ke Yijia
Enter loop current suppression link inhibit DC side voltage (electric current) fluctuation.The method that the present invention uses is first to use low-pass filter
After low frequency wave is filtered out, then remaining two frequency-doubled signal is controlled using PR, and then DC voltage (electric current) can be inhibited
Two frequencys multiplication keep DC voltage (electric current) to stablize.
Step S8：According to upper and lower bridge arm voltage dropWherein, ujp、ujnFor the voltage of upper underarm；
udcFor DC voltage；vjFor the output voltage of exchange side；ucirjThe pressure drop generated for circulating current.J is j phases, takes a, b, c.
The required control signal of phase shift carrier wave is generated, and then MMC is controlled.
The present invention can ensure that ac-side current is that three-phase symmetrical sine wave, active power and reactive power are invariable
(being fluctuated without second harmonic).
The overall structure block diagram of MMC control systems is as shown in Figure 3.Three-phase voltage current signal is obtained from exchange side first,
Then three-phase voltage current signal is transformed to by 3s/2s under two-phase stationary coordinate system.Due to active and reactive power reference value
Calculating need voltage fundamental positive-sequence component, so voltage signal after being converted by 3s/2s, will also extract its positive-sequence signals,
According to the service requirement of the different control targes of MMC two under the conditions of unbalanced source voltage, the ginseng of active/reactive power is calculated
Value is examined, after the reference value of active/reactive power and instantaneous value are made difference, the link of sliding formwork control design has been put into, ring is added
Stream inhibits link, carries out phase shift carrier modulation, to generate control signal, is used for the control of upper and lower 6 bridge arms of MMC.
The method of the embodiment of the present invention is to build simulation model based on MATLAB/Simulink according to MMC-HVDC systems
It has carried out simulation comparison experiment and has carried out experimental verification on experimental prototype.MMC emulates major parameter and table 1 is arranged：
Table 1
When unbalanced source voltage, the electric current and active and reactive power of exchange side can all fluctuate.Here it tests
Condition is that exchange side A phase voltages drop to 6.3kV, and B phases keep the equilibrium state of former 7kV with C phases.
Fig. 4~9 are respectively the simulation curve of the sliding formwork control in the conventional PI controls of 1 time use of control targe, this paper.Figure
10 and Figure 11 in order to control 1 time PI of target controls, control method of the present invention A phase current frequency spectrums；Figure 12~17 are respectively to control
The PI controls of 2 times use routines of target, the simulation curve of this paper sliding formwork controls.Specifically simulated effect is：
(1) by Fig. 4, Fig. 7 as it can be seen that the sliding formwork control designed using conventional PI controls and the present invention can reach elimination
The negative sequence component of current on line side so that exchange side, which exchanges, remains the effect of three-phase symmetrical sinusoidal ac, it was demonstrated that this literary grace
The validity of sliding formwork control can all reach steady-state value, explanation in a relatively short period of time using PI controls or sliding formwork control
Both control methods all have good rapidity.But by the A phase currents frequency spectrum of Fig. 6 as it can be seen that A phases are electric when being controlled using PI
The total harmonic distortion of stream is 10.60%, and is only 4.41% using the total harmonic distortion of A phase currents when the sliding formwork control of this paper,
Therefore, it is controlled compared to PI, it is also stronger using the power quality higher of system, the robustness of system when sliding formwork control.But from figure
5, active/idle waveform of Fig. 6 and Fig. 8, Fig. 9 are as it can be seen that in control targe 1 time two methods of PI controls, sliding formwork control to power
Fluctuation equal unrestraint effect, can all fluctuate.Therefore, current on line side is born in two kinds of controls under the conditions of unbalanced power supply
Order components inhibit all have preferable rapidity and stability, but more using the power quality after system stabilization when sliding formwork control
It is good.
(2) by Figure 13, Figure 14 and Figure 16, Figure 17 as it can be seen that using the sliding formwork control of conventional PI controls and this paper all to work(
Inhibiting effect is played in rate fluctuation, ensures that power maintains to stablize.But it may refrain from for effect, controlled to power waves using conventional PI
Dynamic inhibition is not satisfactory, still will appear fluctuation by a small margin.And use the sliding formwork control of this paper that can then completely inhibit
The secondary fluctuation of power, therefore, using this paper sliding formwork control when, exchange side is active/reactive power stabilizer is more preferable.But from figure
For ac-side current waveform under the two methods of 12 and Figure 15 as it can be seen that when being realized to control targe 2, two methods can all make exchange
There is negative-sequence current in side electric current, this makes ac-side current no longer three-phase symmetrical.
The present invention has also built the MMC current transformer hardware experiment platforms with 10 submodules, and is carried out on this platform
Experimental test.For the sake of security, it is 310V, control that DC side, which uses D.C. regulated power supply 100V, exchange side power grid phase voltage,
Signal is generated by TMS320F28335 type dsp controllers, and switching device selects the BSM100GB120DN2K of Siemens series, it
IGBT module by carrying inverse parallel fly-wheel diode forms.
On this hardware prototype experiment platform, experiment examination is carried out using the control method of this paper under two kinds of control targes
It tests, by oscillograph it is observed that the oscillogram of electric current, power, as shown in Figure 18, Figure 19, Figure 20 and Figure 21.
Shown in Figure 18, Figure 19, Figure 20 and Figure 21 as it can be seen that under control targe 1, DC side three-phase alternating current is realized
Non-negative sequence current, but active power and reactive power can fluctuate；Under control targe 2, power can keep stable, but electric current
It can fluctuate.The result tested on hardware experiment platform and simulation waveform basic one on Matlab/Simulink software platforms
It causes, hardware platform experimental result more fully demonstrates the validity of this paper sliding formwork controls.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
Those familiar with the art in the technical scope disclosed by the present invention, can readily occur in various equivalent modifications or replace
It changes, these modifications or substitutions should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with right
It is required that protection domain subject to.
Claims (8)
1. a kind of MMC nonlinear control methods based on sliding formwork control, which is characterized in that the method includes the following steps：
S1, three-phase voltage current signal of being changed commanders using 3s/2s changes are converted under two-phase stationary coordinate system；
S2, fundamental positive sequence extraction is carried out, carries out active power using fundamental positive sequence and reactive power reference qref calculates；
S3, active power reference value and active power instantaneous value are made it is poor, by reactive power reference qref and reactive power instantaneous value
It is poor to make, and difference is inputted to sliding formwork control module respectively；
S4, summarized using sliding formwork control module output valve and loop current suppression controller output valve, direct voltage output value after as move
Phase carrier modulation inputs, and MMC bridge arm controls are carried out using phase shift carrier modulation output signal.
2. a kind of MMC nonlinear control methods based on sliding formwork control according to claim 1, which is characterized in that described
Step S3 in sliding formwork control module to choose active deviation and idle deviation be 0 to be used as sliding-mode surface：
Wherein, SP(S)、SQ(S) it is active and reactive power sliding-mode surface；Pref、QrefFor the reference of active power and reactive power
Value；P, Q is respectively the instantaneous value of active power and reactive power.
3. a kind of MMC nonlinear control methods based on sliding formwork control according to claim 1, which is characterized in that reach
Sliding-mode surface time computational methods：
Wherein, TP、TQThe time of active power and reactive power sliding-mode surface is reached for original state；K11、K12、K21、K22To adjust
Coefficient；SP0、SQ0For the initial value of active power and reactive power.
4. a kind of MMC nonlinear control methods based on sliding formwork control according to claim 1, which is characterized in that described
Step S3 in active power instantaneous value calculated by two-phase voltage and biphase current, reactive power instantaneous value passes through two-phase voltage
It is calculated with biphase current, calculation formula is：
Wherein, P, Q are respectively active power instantaneous value, reactive power instantaneous value；usα、usβ、isα、isβRespectively exchange side three-phase
Component of the voltage and current under two-phase stationary coordinate system.
5. a kind of MMC nonlinear control methods based on sliding formwork control according to claim 1, which is characterized in that described
Step S3 in active power reference value and reactive power reference qref carry out respective value settings according to two control targes respectively,
Two control targes include：
A. ac-side current is without negative sequence componentActive power and reactive power reference qref are under the target：
Wherein, Pref、QrefThe respectively reference value of active power and reactive power, usα、usβRespectively three-phase voltage of ac exists
Two-phase stationary coordinate system component；Respectively positive-sequence component of the three-phase current of ac under two-phase stationary coordinate system；
B. active power and reactive power are without fluctuation, and active power and reactive power reference qref are under the target：
Pref=Pcom、Qref=Qcom
In formula：Pref、QrefThe respectively reference value of active power and reactive power, Pcom、QcomRespectively active power and idle
Power given value.
6. a kind of MMC nonlinear control methods based on sliding formwork control according to claim 1, which is characterized in that described
Step S4 in be input to the signal of phase shift carrier modulation and be：
Wherein, ujp、ujnFor the voltage of upper underarm；udcFor DC voltage；vjFor the output voltage of exchange side；ucirjFor cycle electricity
The raw pressure drop of miscarriage.
7. a kind of MMC nonlinear control methods based on sliding formwork control according to claim 1, which is characterized in that described
Loop current suppression controller filter out low frequency wave first with low-pass filter, then PR is carried out to two frequency-doubled signals after filtered
Control inhibits two frequencys multiplication of DC voltage or electric current.
8. a kind of MMC nonlinear control methods based on sliding formwork control according to claim 1, which is characterized in that described
Step S4 in loop current suppression controller input terminal connect DC current signal output end.
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| CN111725832A (en) * | 2020-06-05 | 2020-09-29 | 西安交通大学 | Direct-current side voltage indirect control method of multi-terminal flexible power transmission system based on simplified offline algorithm |
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| CN113193583A (en) * | 2021-04-19 | 2021-07-30 | 中国电建集团华东勘测设计研究院有限公司 | Sending-end MMC sliding mode variable structure control method for offshore wind field flexible direct-current power transmission system |
| CN113193583B (en) * | 2021-04-19 | 2022-07-05 | 中国电建集团华东勘测设计研究院有限公司 | Sending-end MMC sliding mode variable structure control method for offshore wind field flexible and straight system |
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