CN111244980B - Nonlinear control method of power electronic transformer based on MMC structure - Google Patents
Nonlinear control method of power electronic transformer based on MMC structure Download PDFInfo
- Publication number
- CN111244980B CN111244980B CN202010074332.XA CN202010074332A CN111244980B CN 111244980 B CN111244980 B CN 111244980B CN 202010074332 A CN202010074332 A CN 202010074332A CN 111244980 B CN111244980 B CN 111244980B
- Authority
- CN
- China
- Prior art keywords
- phase
- voltage
- mmc
- input stage
- electronic transformer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000013178 mathematical model Methods 0.000 claims abstract description 53
- 238000011217 control strategy Methods 0.000 claims abstract description 45
- 238000002955 isolation Methods 0.000 claims abstract description 22
- 230000001629 suppression Effects 0.000 claims abstract description 12
- 238000006243 chemical reaction Methods 0.000 claims abstract description 5
- 230000001052 transient effect Effects 0.000 claims description 9
- 230000010363 phase shift Effects 0.000 claims description 6
- 230000003068 static effect Effects 0.000 claims description 6
- 239000003990 capacitor Substances 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 9
- 238000004088 simulation Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012887 quadratic function Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229960001948 caffeine Drugs 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- RYYVLZVUVIJVGH-UHFFFAOYSA-N trimethylxanthine Natural products CN1C(=O)N(C)C(=O)C2=C1N=CN2C RYYVLZVUVIJVGH-UHFFFAOYSA-N 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- 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
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
-
- 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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
-
- 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
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M7/219—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
-
- 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
- H02M7/53—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 using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
-
- 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
- H02M1/00—Details of apparatus for conversion
- H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
- H02M1/007—Plural converter units in cascade
-
- 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
- Y02E40/30—Reactive power compensation
-
- 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
-
- 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]
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
- Ac-Ac Conversion (AREA)
Abstract
The invention relates to a nonlinear control method of a power electronic transformer based on an MMC structure, which comprises the following steps: s1, establishing mathematical models of an alternating current side and a direct current side of an input stage; s2, obtaining an input stage alternating current side mathematical model under a dq two-phase coordinate system through coordinate conversion; s3, respectively constructing an inner loop control strategy, an outer loop control strategy and a loop suppression strategy of the input stage of the MMC power electronic transformer based on the Lyapunov function by combining an input stage direct current side mathematical model and an input stage alternating current side mathematical model under a dq two-phase coordinate system; s4, constructing a phase-shifting voltage-regulating control strategy of the intermediate isolation level; s5, constructing an output stage inner ring control strategy and an output stage outer ring control strategy. Compared with the prior art, the invention constructs corresponding control strategies for the input stage, the middle isolation stage and the output stage of the MMC power electronic transformer respectively, can comprehensively and effectively control the power grid during fault, can improve the voltage stability, and simultaneously ensures the power supply power quality.
Description
Technical Field
The invention relates to the technical field of MMC power electronic transformer control, in particular to a nonlinear control method of a power electronic transformer based on an MMC structure when power grid voltage is unbalanced.
Background
In the power system, the transformer is the most reliable and widely used electric equipment, and in recent years, with the rapid development of distributed energy sources, the nonlinear loads used by the power users in industry, commerce and houses are increasing, and the requirements of the current power system cannot be met due to the lack of flexibility and bidirectional energy control capability of the traditional distribution transformer.
The power electronic transformer (Power Electronic Transformer, PET) using the high frequency transformer has incomparable advantages compared with the traditional transformer in terms of voltage dip compensation, instantaneous voltage regulation, power factor correction, harmonic suppression and the like, and meanwhile, the PET has the advantages of smaller volume and weight; the modularized multi-level converter (Modular Multilevel Converter, MMC) technology has the advantages of being large in output level number, good in electromagnetic compatibility, low in harmonic content, low in voltage endurance requirement of switching devices, small in switching loss and the like. In a medium-high voltage power network, MMC-PET obtained by combining MMC technology with a Power Electronic Transformer (PET) has become a trend of development at home and abroad. However, when the voltage of the power grid fails, for MMC-PET, the current and power of the external alternating current side of the MMC-PET will fluctuate, and the voltage of the direct current side will also fluctuate, so that the voltage stability of the power system and the power quality for supplying power to the low-voltage side power grid will be seriously affected.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a nonlinear control method of a power electronic transformer based on an MMC structure, which is characterized in that corresponding control strategies are respectively constructed for an input stage, an intermediate isolation stage and an output stage so as to improve the voltage stability of an alternating current side and a direct current side when the voltage of a power grid is unbalanced, and simultaneously ensure the quality of power supply electric energy.
The aim of the invention can be achieved by the following technical scheme: a nonlinear control method of a power electronic transformer based on an MMC structure comprises the following steps:
s1, establishing an input stage alternating current side mathematical model and a direct current side mathematical model according to a topological structure of an MMC power electronic transformer, wherein the three phases of the input stage alternating current side consist of an upper bridge arm and a lower bridge arm, each bridge arm consists of a plurality of sub-modules, bridge arm inductors and bridge arm equivalent resistors which are sequentially connected in series, and each sub-module consists of two half-bridges with anti-parallel diode IGBT and a capacitor which are connected in parallel;
s2, carrying out coordinate conversion on the mathematical model of the input stage alternating-current side to obtain a mathematical model of the input stage alternating-current side under a dq two-phase coordinate system;
s3, respectively constructing an inner loop control strategy, an outer loop control strategy and a loop suppression strategy of the input stage of the MMC power electronic transformer based on the Lyapunov function by combining an input stage direct current side mathematical model and an input stage alternating current side mathematical model under a dq two-phase coordinate system;
s4, constructing a phase-shifting voltage-regulating control strategy of an intermediate isolation stage according to the topological structure of the MMC power electronic transformer, wherein the intermediate isolation stage is specifically an active double-bridge DC/DC converter;
s5, respectively constructing an output stage inner ring control strategy and an output stage outer ring control strategy according to the topological structure of the MMC power electronic transformer, wherein the output stage is specifically a three-phase full-bridge voltage type converter.
Further, the step S1 is specifically based on Kirchhoff' S law to build mathematical models of the ac side and the dc side of the input stage, where the mathematical models of the ac side of the input stage are specifically:
L s ＝L T +L/2
R s ＝R T +R/2
wherein ,uva 、u vb 、u vc Three-phase alternating voltage of MMC input stage, u a 、u b 、u c For three-phase voltage on the grid side, i a 、i b 、i c For three-phase current on the grid side, R s 、L s Respectively equivalent resistance and equivalent inductance of the power transmission line, R T 、L T The equivalent resistance and the equivalent inductance of the power grid side line are respectively shown, and R, L is the bridge arm resistance and the bridge arm inductance of the MMC respectively;
the input stage direct current side mathematical model specifically comprises the following steps:
wherein ,udc For the DC voltage of the MMC input stage, u jp 、u jn Voltages of upper and lower arms of j phases respectively, i cirj Is the circulation of j phase, i jp 、i jn The current of the upper bridge arm and the lower bridge arm of the j phase are respectively.
Further, in the step S2, the mathematical model of the ac side of the input stage under the dq two-phase coordinate system is specifically:
wherein ω is the angular frequency of the AC system at the grid side, u d 、u q Respectively the d-axis component and the q-axis component, i of the three-phase alternating voltage at the power grid side under a two-phase rotating coordinate system d 、i q Respectively the d-axis component and the q-axis component of the three-phase current at the power grid side under a two-phase rotation coordinate system, and u sd 、u sq The d and q axis components of the three-phase alternating voltage at the MMC input side under a two-phase rotating coordinate system are respectively shown.
Further, the step S3 specifically includes the following steps:
s31, determining electromagnetic transient equations of an alternating current side and a direct current side of an input stage of the MMC power electronic transformer in a positive sequence system according to the mathematical model of the direct current side of the input stage and the mathematical model of the alternating current side of the input stage under a dq two-phase coordinate system;
s32, obtaining a switching function of an input stage of the MMC power electronic transformer under a positive sequence system based on an Lyapunov function and electromagnetic transient equations of the input stage of the MMC power electronic transformer on an alternating current side and a direct current side in the positive sequence system, namely an inner ring control strategy and a voltage outer ring control strategy of positive and negative sequence current of the input stage of the MMC power electronic transformer, wherein the voltage outer ring control strategy adopts constant direct current voltage and constant reactive power control;
s33, constructing a double frequency circulation mathematical model aiming at circulation components on an input stage bridge arm of the MMC power electronic transformer, namely an input stage circulation suppression strategy of the MMC power electronic transformer.
Further, in the step S31, the electromagnetic transient equations of the input stage of the MMC power electronic transformer on the ac side and the dc side in the positive sequence system are specifically:
wherein ,d-axis component and q-axis component of AC side voltage under positive sequence system, +.>Is the reference value of d-axis and q-axis components of three-phase current at the power grid side under a positive sequence system, S dref and Sqref Respectively as a switching function S d 、S q Reference value of->Is the reference value of the DC side voltage, +.>The current reference value is a direct-current side current reference value, N is the number of submodules in an input-stage bridge arm, and C is a capacitance value in the submodules;
the switching function of the input stage of the MMC power electronic transformer under the positive sequence system in step S32 is specifically:
wherein ,respectively a d-axis switching function and a q-axis switching function of an input stage of the MMC power electronic transformer under a positive sequence system, wherein alpha and beta are outer ring control coefficients, and u is the same as the input stage of the MMC power electronic transformer under the positive sequence system dcact Is the actual value of the DC side voltage, gamma 0 As intermediate variable, x 1 、x 2 and x3 All are state variables>D and q axis components of the three-phase current at the power grid side under the positive sequence system under the two-phase rotation coordinate system are respectively;
the double frequency circulation mathematical model in the step S33 specifically includes:
wherein ,voltage at phase j for zero sequence component of double frequency circulation,/>For zero sequence loop component>Is the zero sequence circulation component instruction value, k p For the circulation suppression scale factor, k i The integral coefficient is suppressed for the circulation.
Further, the step S4 specifically includes the following steps:
s41, obtaining an output active power model according to the structure of the active double-bridge DC/DC converter:
wherein ,Ll Is leakage inductance of high-frequency transformer, f s For the switching frequency of the switching tube, u dcL D is the duty ratio of the single-phase bridge type full-control converter at the high voltage side;
s42, converting the low-voltage side DC voltage u dcL And output voltage reference valueAfter the difference is made, a phase shift reference value theta is obtained through a first non-static difference PI controller * The switching tube trigger signal of the DC/DC converter is used as a phase-shifting voltage-regulating control strategy of the intermediate isolation stage.
Further, the phase shift reference value θ in the step S42 * The method comprises the following steps:
wherein ,kp1 For the proportional coefficient, k, of the first non-static difference PI controller i1 Integrating the coefficient for a first non-static difference PI controller;
further, the step S5 specifically includes the following steps:
s51, establishing a steady-state mathematical model of the three-phase full-bridge voltage type converter under a dq two-phase coordinate system;
s52, constructing an MMC-PET output stage positive and negative sequence current inner loop control strategy and an outer loop control strategy adopting constant alternating voltage and constant reactive power control according to the positive and negative sequence currents of the output stage based on a Lyapunov function and a steady state mathematical model of the three-phase full-bridge voltage type converter.
Further, the steady-state mathematical model of the three-phase full-bridge voltage type converter in step S51 is specifically:
wherein ,ucd 、u cq Bridge arm midpoint voltage u of three-phase full-bridge voltage type converter A 、u B 、u C D, q-axis components, i in two-phase rotational coordinate system sd 、i sq The components of d and q axes of the output current of the three-phase full-bridge voltage type converter under a two-phase rotating coordinate system are respectively, u sd 、u sq Three-phase voltage u output by three-phase full-bridge voltage type converter respectively A0 、u B0 、u C0 D, q-axis components, R in two-phase rotational coordinate system d Is the equivalent resistance of the three-phase full-bridge voltage type converter, L d Is the equivalent inductance of the three-phase full-bridge voltage type converter.
Compared with the prior art, the invention constructs corresponding control strategies for the input stage, the intermediate isolation stage and the output stage of the MMC power electronic transformer respectively so as to be capable of comprehensively and effectively controlling when a power grid fails, wherein for the input stage, the invention separates positive and negative zero sequences of voltage and current input by the power grid so as to respectively control the positive and negative zero sequences of the current, constructs an inner loop control strategy of the positive and negative sequence current of the input stage based on a Lyapunov function, designs a zero sequence current PI controller, adopts an outer loop control strategy of constant direct current voltage and reactive power control so as to reduce the influence of the power grid voltage failure on the direct current voltage, and constructs an input loop suppression strategy so as to improve the integral dynamic performance of the MMC power electronic transformer, namely the stability of direct current voltage output;
for the middle isolation stage, the invention adopts a control strategy of phase shifting and voltage regulating, and when the voltage of the power grid fails, the influence of voltage fluctuation of the direct current side of the input stage of the MMC power electronic transformer on the power grid at the low voltage side is further reduced;
for the output stage, the invention designs an output stage positive and negative sequence current inner loop control strategy based on Lyapunov function aiming at positive and negative currents generated when the power grid at the output side fails, and adopts fixed alternating voltage control and fixed reactive power control to perform outer loop control so as to further reduce the influence of fluctuation of reactive power on the power grid at the low voltage side when the power grid fails, improve the stability of alternating voltage output and effectively ensure the quality of electric energy.
Drawings
FIG. 1 is a schematic flow chart of the method of the present invention;
FIG. 2 is a topology of an MMC power electronic transformer;
FIG. 3 (a) is a general control block diagram of an input stage of an MMC power electronic transformer according to the invention;
FIG. 3 (b) is a block diagram of loop current suppression control for an input stage of an MMC power electronic transformer of the present invention;
FIG. 3 (c) is a control block diagram of an intermediate isolation stage of the MMC power electronic transformer of the present invention;
FIG. 3 (d) is a control block diagram of an output stage of the MMC power electronic transformer of the present invention;
FIG. 4 is a waveform of capacitance and voltage of an input stage MMC submodule of the MMC power electronic transformer according to the present invention during normal operation;
FIG. 5 is a waveform of the MMC circulating current of the input stage of the MMC power electronic transformer of the invention during normal operation;
FIG. 6 is a waveform of the MMC-PET input side grid voltage of object 1 according to an embodiment of the present invention;
FIG. 7 is a waveform of MMC-PET input side grid current for object 1 of an embodiment of the present invention;
FIG. 8 is a MMC-PET input stage power waveform of object 1 of an embodiment of the present invention;
FIG. 9 is a DC side voltage waveform of an MMC-PET input stage of object 1 according to an embodiment of the present invention;
FIG. 10 is a DC voltage waveform of the MMC-PET isolation level output of object 1 according to an embodiment of the present invention;
FIG. 11 is a waveform of the output power of the MMC-PET output stage of object 1 according to an embodiment of the present invention;
FIG. 12 is a waveform of the output voltage of the MMC-PET output stage of object 1 according to an embodiment of the present invention;
FIG. 13 is a waveform of the output current of the MMC-PET output stage of object 1 according to an embodiment of the present invention;
FIG. 14 is a waveform of the MMC-PET input side grid voltage of object 2 of an embodiment of the present invention;
FIG. 15 is a waveform of MMC-PET input side grid current for object 2 of an embodiment of the present invention;
FIG. 16 is a MMC-PET input stage power waveform of object 2 of an embodiment of the present invention;
FIG. 17 is a DC side voltage waveform of an MMC-PET input stage of object 2 according to an embodiment of the present invention;
FIG. 18 is a DC voltage waveform of the MMC-PET isolation level output of object 2 according to an embodiment of the present invention;
FIG. 19 is a waveform of the output power of the MMC-PET output stage of object 2 according to an embodiment of the present invention;
FIG. 20 is a waveform of the output voltage of the MMC-PET output stage of object 2 according to an embodiment of the present invention;
FIG. 21 is a waveform of the output current of the MMC-PET output stage of object 2 according to an embodiment of the present invention.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples.
Examples
As shown in fig. 1, a power transformer nonlinear control method based on an MMC structure includes the following steps:
s1, establishing an input stage alternating current side mathematical model and a direct current side mathematical model according to a topological structure of an MMC power electronic transformer;
s2, carrying out coordinate conversion on the mathematical model of the input stage alternating-current side to obtain a mathematical model of the input stage alternating-current side under a dq two-phase coordinate system;
s3, respectively constructing an inner loop control strategy, an outer loop control strategy and a loop suppression strategy of the input stage of the MMC power electronic transformer based on the Lyapunov function by combining an input stage direct current side mathematical model and an input stage alternating current side mathematical model under a dq two-phase coordinate system;
s4, constructing a middle isolation level phase-shifting voltage-regulating control strategy according to the topological structure of the MMC power electronic transformer;
s5, respectively constructing an output stage inner ring control strategy and an output stage outer ring control strategy according to the topological structure of the MMC power electronic transformer.
The topological structure of the MMC power electronic transformer is shown in fig. 2, the three phases of the alternating current side of the input stage are composed of an upper bridge arm and a lower bridge arm, each bridge arm is composed of a plurality of sub-modules, bridge arm inductors and bridge arm equivalent resistors which are sequentially connected in series, and each sub-module is composed of two half-bridges with anti-parallel diode IGBTs and a capacitor which are connected in parallel;
the intermediate isolation stage is specifically an active double-bridge DC/DC converter;
the output stage is specifically a three-phase full-bridge voltage type converter, namely a three-phase inverter.
The specific process of applying the method to the embodiment includes:
step one, establishing an input stage mathematical model of an MMC power electronic transformer: according to an MMC topological structure, respectively constructing mathematical models of an alternating current side and a direct current side of the MMC based on Kirchhoff law;
step two, two-phase rotation coordinate conversion: according to the coordinate transformation theory, transforming the mathematical model of the MMC alternating current side into the mathematical model of the alternating current side under the dq two-phase rotating coordinate system;
designing an inner ring control strategy of MMC-PET input stage positive and negative sequence current of an MMC power electronic transformer input stage based on Lyapunov function under grid voltage faults;
analyzing the value range of the outer ring control coefficient to cope with the influence when the given reference value and the actual value of the voltage outer ring are not consistent;
step five, designing a positive and negative zero sequence 2-frequency doubling circulation controller for inhibiting positive and negative zero sequence double frequency circulation in an MMC-PET input stage bridge arm;
step six, a control strategy of the intermediate stage of the MMC power electronic transformer under the power grid voltage fault is as follows: the control strategy of phase shifting and voltage regulating is adopted, and when the voltage of the power grid fails, the influence of voltage fluctuation on the direct current side of the MMC-PET input stage on the system is further reduced;
step seven, designing a positive and negative sequence current inner loop control strategy of the MMC-PET output stage based on Lyapunov function aiming at positive and negative currents generated during power grid faults of the output side for the three-phase voltage type full-bridge inverter of the MMC-PET output side, wherein the outer loop adopts fixed alternating voltage control and fixed reactive power control.
In the first step, the mathematical model expressions of the ac side and the dc side of the input stage of the MMC power electronic transformer are:
wherein ,Ls ＝L T +L/2，R s ＝R T +R/2，
in the formula ：uva 、u vb 、u vc Three-phase alternating voltage at the input side of the MMC; ua, ub, uc are three-phase voltages on the grid side; i.e a 、i b 、i c Three-phase current at the power grid side; r is R s 、L s Respectively representing the equivalent resistance and the equivalent inductance of the power transmission line; r is R T 、L T The equivalent resistance and the equivalent inductance of the power grid side line are respectively; r, L are the bridge arm resistance and the bridge arm inductance of the MMC respectively.
wherein ,
in the formula ：icirj A loop current of j (j=a, b, c) phase; u (u) jp 、u jn The voltages of the upper bridge arm and the lower bridge arm of the j phase are respectively; r, L are the bridge arm resistance and the bridge arm inductance of the MMC respectively.
In step two, a two-phase rotational coordinate transformation is performed. The mathematical model of the alternating current side of the input stage of the MMC power electronic transformer under the dq two-phase rotating coordinate system is as follows:
wherein: omega is the angular frequency of the alternating current system at the power grid side; u (u) d 、u q D and q axis components of the three-phase alternating voltage at the power grid side under a two-phase rotating coordinate system are respectively shown; i.e d 、i q D and q axis components of the three-phase current at the power grid side under a two-phase rotation coordinate system are respectively shown; u (u) sd 、u sq The d and q axis components of the three-phase alternating voltage at the MMC input side under a two-phase rotating coordinate system are respectively shown.
In the third step, an inner loop control strategy of MMC-PET input stage positive and negative sequence current based on Lyapunov function under grid voltage fault of an MMC power electronic transformer input stage is designed:
the electromagnetic transient equations for the ac side and the dc side of the input stage of MMC-PET are:
wherein ,
in the formula ,a steady state value that is a switching function; Δd, Δq are the fluctuating components of the switching function.
When the power grid breaks down, the control target of the MMC-PET input stage is to stabilize the output direct-current voltage, restrain the output direct-current voltage from greatly fluctuating, and simultaneously enable the output reactive power to be maintained near the target value. For a positive and negative sequence system, the control objective of the controller is to enable the positive sequence currents of d and q axes to track a given current reference value, and when the controller is stabilized at the d and q axis positive sequence current stabilization reference value, electromagnetic transient equations of an alternating current side and a direct current side of an input stage of MMC-PET in the positive sequence system are respectively as follows:
in the formula ,the reference values of d and q axis components of three-phase current at the power grid side are used; s is S dref 、S qref Reference values for the d, q-axis components of the switching function; />Is a reference value of the direct current side voltage; />Is a direct current side current reference value.
Is available in the form of
Let the state variables of the system be:
let the impedance of the DC side be X dc Can obtain i dc ＝u dc /X dc The MMC-PET input stage model based on Lyapunov function in positive sequence is as follows:
according to Lyapunov stabilization theory, the system, whether linear or nonlinear, is globally progressively stable when the following conditions are satisfied: 1. v (0) =0;
2. v (x) >0 for arbitrary x+.0;
3. for any x +.0,
4. when x goes to infinity, V (x) tends to infinity.
Let Lyapunov function of MMC-PET input stage under positive sequence be taken as:
and deriving the above method to obtain:
the method comprises the following steps:
selecting:
wherein alpha and beta are outer ring control coefficients.
The switching function of the MMC-PET input stage based on Lyapunov function under the positive sequence system is as follows:
the control block diagram corresponding to the switching function is shown in fig. 3 (a).
In the fourth step, the range of values of the two coefficients α and β is analyzed to cope with the influence when the given reference value of the voltage outer loop does not match the actual value.
Assume that the expected value of the system at time t isThe actual value is +.>The derivative of the Lyapunov function chosen is:
can be converted into according to the above:
wherein, alpha is less than 0, beta is less than 0, if simultaneously:
thenNegative definite, assume
Under imprecise control, the above can be appliedThe transformation is as follows:
respectively making:
the method can obtain:
in the above, f 1 (m 1 ,m 3 ) And f 2 (m 2 ,m 3 ) At the same time greater than 0, thenAnd (5) negative setting.
Let m 3 ＝h 1 m 1 、m 3 ＝h 2 m 2 Then
Order theIn the formula, the function lambda 1 (r 1 ,γ 1 ,h 1 ) To be about h 1 When h is a quadratic function of 1 ＝(1+γ 1 )/(2γ 1 ) The quadratic function takes the minimum value, which is:
λ 1min ＝R s +r 1 [1-(1+γ 1 ) 2 /(4γ 1 )]
in order to make f 1 (m 1 ,m 3 ) Meets the positive condition, so that the system can be gradually stabilized, and gamma can be obtained 1 The range of the values is as follows:
in the formula ,γ0 ＝1+2R s /r 1 。
When gamma is 1 When as small as possible, the larger the interval of parameter variation that can make the system tend to stabilize.
If the uncertainty interval of the parameter is 1-epsilon < gamma 1 < 1+ε, the maximum value of α can be obtained:
similarly, the maximum value of β available is:
according to the above, the value ranges of alpha and beta under inaccurate control can be determined to ensure the stability of the system.
In a fifth step of the process, the process is carried out,
when the power grid fails, the circulating current components on the MMC-PET input stage MMC bridge arm are as follows:
in the formula ：ida 、i db 、i dc Is a direct current component in a three-phase circulation,the amplitudes of the positive and negative zero sequence components in the double frequency circulation are respectively +.>The primary phases of the positive and negative zero sequence components in the double frequency circulation are respectively.
After the positive and negative sequence double frequency circulation control is put into, the double frequency circulation which can default to the positive and negative sequence is 0, so that the double frequency circulation only contains zero sequence components. The following mathematical model is available:
in the formula ：ujp 、u jn Respectively the bridge arm voltages of the upper and lower bridge arms of the j phase,voltage at phase j for zero sequence component of double frequency circulation,/>Is a zero sequence loop component.
Command value for zero sequence circulation componentThe zero sequence current component controller in the loop can be adopted as follows:
the control block diagram of the above-mentioned loop current suppression is shown in fig. 3 (b).
In step six, the active power transmitted by the DC/DC converter is:
in the formula ：udc The DC voltage at the high voltage side of MMC-PET; l (L) l Leakage inductance of the high-frequency transformer; f (f) s The switching frequency of the switching tube; u (u) dcL Is a direct current voltage at the low voltage side; d is the duty ratio of the high-voltage side single-phase bridge type full-control converter.
From the above, u can be changed by changing the duty ratio of the high-side single-phase bridge type fully-controlled converter dcL Is of a size of (a) and (b). By combining the output voltage with u dcL And output voltage reference valueAfter the difference is made, the phase shift reference value theta is output through a PI controller without static difference * . The switching tube trigger signal of the output DC/DC converter is obtained through carrier phase-shift PWM modulation and can be expressed as:
/>
the control block diagram of the intermediate isolation stage is shown in fig. 3 (c).
In the seventh step, under the dq rotating coordinate system, the steady-state mathematical model of the three-phase full-bridge voltage type converter is:
wherein: angular frequency of alternating current system at omega power grid side, u cd 、u cq Bridge arm midpoint voltage u of three-phase full-bridge voltage type converter A 、u B 、u C D, q-axis components, i in two-phase rotational coordinate system sd 、i sq The components of d and q axes of the output current of the three-phase full-bridge voltage type converter under a two-phase rotating coordinate system are respectively, u sd 、u sq Three-phase voltage u output by three-phase full-bridge voltage type converter respectively A0 、u B0 、u C0 D, q-axis components, R in two-phase rotational coordinate system d Is the equivalent resistance of the three-phase full-bridge voltage type converter, L d Is the equivalent inductance of the three-phase full-bridge voltage type converter. And similarly, according to the third step and the fourth step, an inner ring control strategy of the MMC-PET output stage based on a Lyapunov function under the power grid fault can be obtained, and a corresponding output stage control block diagram is shown in fig. 3 (d).
In order to verify the effectiveness of the method, the embodiment carries out simulation contrast experiments based on constructing a simulation model based on MATLAB/Simulink according to an MMC-HVDC system, and carries out experimental verification on an experimental prototype. The simulation main parameter settings are as follows:
TABLE 1
When the power grid normally operates, the capacitance voltage waveform of the input stage MMC submodule and the circulation waveform of the input stage MMC are respectively shown in fig. 4 and 5 when the MMC power electronic transformer normally operates. The target 1 set in this embodiment is a voltage three-phase voltage sag fault of the grid voltage, the sag causes 50% of the original grid voltage, and the target 2 is a voltage three-phase voltage sag fault of the grid voltage, and the sag causes 130% of the original grid voltage.
The specific simulation effect is as follows:
when the three-phase voltage sag of the power grid is 50%, fig. 6 is an MMC-PET input side power grid voltage waveform at the time of the target 1 fault, the three-phase voltage sag fault occurs at the time of 1.4s-1.5s, fig. 7 is an MMC-PET input side power grid current waveform corresponding to the target 1 fault, fig. 8 is an MMC-PET input stage power waveform corresponding to the target 1 fault, fig. 9 is an MMC-PET input stage direct current side voltage waveform corresponding to the target 1 fault, fig. 10 is an MMC-PET isolation stage output direct current voltage waveform corresponding to the target 1 fault, fig. 11 is an MMC-PET output stage output power waveform corresponding to the target 1 fault, fig. 12 is an MMC-PET output stage output voltage waveform corresponding to the target 1 fault, and fig. 13 is an MMC-PET output stage output current waveform corresponding to the target 1 fault. As can be seen from simulation figures 6 to 13, when a voltage sag occurs suddenly, the output dc voltage of the MMC-PET input stage also decreases, and because the input stage adopts constant dc voltage control and constant reactive power control, the output dc voltage does not decrease to 50% of the original voltage, but only decreases by 7.4%, and reaches a stable state, and meanwhile, the reactive power of the input stage converter is stable and does not generate larger fluctuation. During a grid voltage sag, the rectifier stage of the MMC-PET can maintain a certain active power transmission anyway; the constant direct current of the middle isolation stage controls the control target value to be half of the input value, and a certain control margin is provided, so that the control target value is not obviously reduced; in addition, as the output stage adopts fixed alternating voltage and fixed reactive power control, and combines the energy storage function of a capacitor, under the condition of voltage sag, the active power and the reactive power output by the MMC-PET output stage are not reduced, the output voltage and current are not greatly influenced, the fault low-voltage ride-through capability of a power grid is improved, and the quality of power supply is ensured.
When the three-phase voltage of the power grid is temporarily raised to 130% of the original voltage, fig. 14 is an MMC-PET input side power grid voltage waveform corresponding to the target 2 fault, a three-phase voltage temporary raising fault occurs at 1.4s-1.5s, fig. 15 is an MMC-PET input side power grid current waveform corresponding to the target 2 fault, fig. 16 is an MMC-PET input stage power waveform corresponding to the target 2 fault, fig. 17 is an MMC-PET input stage direct current side voltage waveform corresponding to the target 2 fault, fig. 18 is a direct current voltage waveform output by an MMC-PET isolation stage corresponding to the target 2 fault, fig. 19 is an MMC-PET output stage output power waveform corresponding to the target 2 fault, fig. 20 is an MMC-PET output stage output voltage waveform corresponding to the target 2 fault, and fig. 21 is an MMC-PET output stage output current waveform corresponding to the target 2 fault. When the three-phase voltage of the power grid temporarily rises to 130% of the rated voltage value, as can be seen from simulation diagrams 14-21, when the voltage temporarily rises suddenly, the output direct-current voltage of the MMC-PET input stage also rises, and as the input stage adopts constant direct-current voltage control and constant reactive power control, the output direct-current side voltage does not rise to 150% of the original voltage, but only rises by 38.8%, and reaches a stable state, and meanwhile, the reactive power of the input stage converter is stable and does not generate larger fluctuation; during the power grid voltage transient rising period, the output voltage of the middle isolation stage is kept constant due to the constant direct current control of the middle isolation stage; due to the fact that the output stage is controlled by fixed alternating voltage and fixed reactive power, and the energy storage function of the capacitor is combined, under the condition that voltage is temporarily increased, active power and reactive power output by the MMC-PET output stage are increased, the output voltage and current are not greatly affected, fault high-voltage ride-through capacity of a power grid is improved, and the quality of power supply is effectively guaranteed.
Claims (5)
1. The nonlinear control method of the power electronic transformer based on the MMC structure is characterized by comprising the following steps of:
s1, establishing an input stage alternating current side mathematical model and a direct current side mathematical model according to a topological structure of an MMC power electronic transformer, wherein the three phases of the input stage alternating current side consist of an upper bridge arm and a lower bridge arm, each bridge arm consists of a plurality of sub-modules, bridge arm inductors and bridge arm equivalent resistors which are sequentially connected in series, and each sub-module consists of two half-bridges with anti-parallel diode IGBT and a capacitor which are connected in parallel;
s2, carrying out coordinate conversion on the mathematical model of the input stage alternating-current side to obtain a mathematical model of the input stage alternating-current side under a dq two-phase coordinate system;
s3, respectively constructing an inner loop control strategy, an outer loop control strategy and a loop suppression strategy of the input stage of the MMC power electronic transformer based on the Lyapunov function by combining an input stage direct current side mathematical model and an input stage alternating current side mathematical model under a dq two-phase coordinate system;
s4, constructing a phase-shifting voltage-regulating control strategy of an intermediate isolation stage according to the topological structure of the MMC power electronic transformer, wherein the intermediate isolation stage is specifically an active double-bridge DC/DC converter;
s5, respectively constructing an output stage inner ring control strategy and an output stage outer ring control strategy according to the topological structure of the MMC power electronic transformer, wherein the output stage is specifically a three-phase full-bridge voltage type converter;
the step S1 is specifically based on Kirchhoff' S law to establish an input stage alternating-current side mathematical model and a direct-current side mathematical model, wherein the input stage alternating-current side mathematical model is specifically as follows:
L s ＝L T +L/2
R s ＝R T +R/2
therein, uva, uvb, u vc Three-phase alternating voltage of MMC input stage, u a 、u b 、u c For three-phase voltage on the grid side, i a 、i b 、i c For three-phase current on the grid side, R s 、L s Respectively equivalent resistance and equivalent inductance of the power transmission line, R T 、L T The equivalent resistance and the equivalent inductance of the power grid side line are respectively shown, and R, L is the bridge arm resistance and the bridge arm inductance of the MMC respectively;
the input stage direct current side mathematical model specifically comprises the following steps:
wherein ,udc For the DC voltage of the MMC input stage, u jp 、u jn Voltages of upper and lower arms of j phases respectively, i cirj Is the circulation of j phase, i jp 、i jn Currents of an upper bridge arm and a lower bridge arm of the j phases respectively;
in the step S2, the mathematical model of the ac side of the input stage under the dq two-phase coordinate system is specifically:
wherein ω is the angular frequency of the AC system at the grid side, u d 、u q Respectively the d-axis component and the q-axis component, i of the three-phase alternating voltage at the power grid side under a two-phase rotating coordinate system d 、i q Respectively the d-axis component and the q-axis component of the three-phase current at the power grid side under a two-phase rotation coordinate system, and u sd 、u sq D and q axis components of the three-phase alternating voltage at the MMC input side under a two-phase rotating coordinate system are respectively shown;
the step S3 specifically comprises the following steps:
s31, determining electromagnetic transient equations of an alternating current side and a direct current side of an input stage of the MMC power electronic transformer in a positive sequence system according to the mathematical model of the direct current side of the input stage and the mathematical model of the alternating current side of the input stage under a dq two-phase coordinate system;
s32, obtaining a switching function of an input stage of the MMC power electronic transformer under a positive sequence system based on an Lyapunov function and electromagnetic transient equations of the input stage of the MMC power electronic transformer on an alternating current side and a direct current side in the positive sequence system, namely an inner ring control strategy and a voltage outer ring control strategy of positive and negative sequence current of the input stage of the MMC power electronic transformer, wherein the voltage outer ring control strategy adopts constant direct current voltage and constant reactive power control;
s33, constructing a double frequency circulation mathematical model aiming at circulation components on an input stage bridge arm of the MMC power electronic transformer, namely an input stage circulation suppression strategy of the MMC power electronic transformer;
in the step S31, electromagnetic transient equations of the input stage of the MMC power electronic transformer on the ac side and the dc side in the positive sequence system are specifically as follows:
wherein ,d-axis component and q-axis component of AC side voltage under positive sequence system, +.>Is the reference value of d-axis and q-axis components of three-phase current at the power grid side under a positive sequence system, S dref and Sqref Respectively as a switching function S d 、S q Reference value of->Is the reference value of the DC side voltage, +.>The current reference value is a direct-current side current reference value, N is the number of submodules in an input-stage bridge arm, and C is a capacitance value in the submodules;
the switching function of the input stage of the MMC power electronic transformer under the positive sequence system in step S32 is specifically:
wherein ,respectively a d-axis switching function and a q-axis switching function of an input stage of the MMC power electronic transformer under a positive sequence system, wherein alpha and beta are outer ring control coefficients, and u is the same as the input stage of the MMC power electronic transformer under the positive sequence system dcact Is the actual value of the DC side voltage, gamma 0 As intermediate variable, x 1 、x 2 and x3 All are state variables>D and q axis components of the three-phase current at the power grid side under the positive sequence system under the two-phase rotation coordinate system are respectively;
the double frequency circulation mathematical model in the step S33 specifically includes:
wherein ,voltage at phase j for zero sequence component of double frequency circulation,/>For zero sequence loop component>Is the zero sequence circulation component instruction value, k p For the circulation suppression scale factor, k i The integral coefficient is suppressed for the circulation.
2. The method for nonlinear control of a power electronic transformer based on an MMC structure according to claim 1, wherein the step S4 specifically includes the steps of:
s41, obtaining an output active power model according to the structure of the active double-bridge DC/DC converter:
wherein ,Ll Is leakage inductance of high-frequency transformer, f s For the switching frequency of the switching tube, u dcL D is the duty ratio of the single-phase bridge type full-control converter at the high voltage side;
s42, converting the low-voltage side DC voltage u dcL And output voltage reference valueAfter the difference is made, a phase shift reference value theta is obtained through a first non-static difference PI controller * The switching tube trigger signal of the DC/DC converter is used as a phase-shifting voltage-regulating control strategy of the intermediate isolation stage.
3. The method for nonlinear control of power electronic transformer based on MMC structure according to claim 2, wherein said method comprises the steps ofThe phase shift reference value θ in step S42 * The method comprises the following steps:
wherein ,kp1 For the proportional coefficient, k, of the first non-static difference PI controller i1 The coefficients are integrated for the first dead-beat PI controller.
4. The method for nonlinear control of a power electronic transformer based on an MMC structure according to claim 1, wherein the step S5 specifically includes the steps of:
s51, establishing a steady-state mathematical model of the three-phase full-bridge voltage type converter under a dq two-phase coordinate system;
s52, constructing an MMC-PET output stage positive and negative sequence current inner loop control strategy and an outer loop control strategy adopting constant alternating voltage and constant reactive power control according to the positive and negative sequence currents of the output stage based on a Lyapunov function and a steady state mathematical model of the three-phase full-bridge voltage type converter.
5. The nonlinear control method of the power electronic transformer based on the MMC structure as claimed in claim 4, wherein the steady-state mathematical model of the three-phase full-bridge voltage type converter in step S51 is specifically:
wherein ,ucd 、u cq Bridge arm midpoint voltage u of three-phase full-bridge voltage type converter A 、u B 、u C D, q-axis components, i in two-phase rotational coordinate system sd 、i sq The components of d and q axes of the output current of the three-phase full-bridge voltage type converter under a two-phase rotating coordinate system are respectively, u sd 、u sq Three-phase voltage u output by three-phase full-bridge voltage type converter respectively A0 、u B0 、u C0 In two phases of rotationD, q axis components in a rotating coordinate system, R d Is the equivalent resistance of the three-phase full-bridge voltage type converter, L d Is the equivalent inductance of the three-phase full-bridge voltage type converter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010074332.XA CN111244980B (en) | 2020-01-22 | 2020-01-22 | Nonlinear control method of power electronic transformer based on MMC structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010074332.XA CN111244980B (en) | 2020-01-22 | 2020-01-22 | Nonlinear control method of power electronic transformer based on MMC structure |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111244980A CN111244980A (en) | 2020-06-05 |
| CN111244980B true CN111244980B (en) | 2023-08-29 |
Family
ID=70866131
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010074332.XA Active CN111244980B (en) | 2020-01-22 | 2020-01-22 | Nonlinear control method of power electronic transformer based on MMC structure |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111244980B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112600431A (en) * | 2020-11-05 | 2021-04-02 | 上海电力大学 | MMC-based model prediction control method for SST novel DAB DC-DC converter |
| CN112701946B (en) * | 2020-12-14 | 2022-08-19 | 广东安朴电力技术有限公司 | MMC bridge arm current balance control method and control system |
| CN113541515B (en) * | 2021-06-07 | 2022-11-22 | 国网福建省电力有限公司泉州供电公司 | Control method and terminal for AC/DC bus interface converter |
| CN116683772A (en) * | 2023-05-30 | 2023-09-01 | 西南交通大学 | Vehicle-mounted power electronic transformer structure and operation control method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109217687A (en) * | 2018-08-24 | 2019-01-15 | 南京理工大学 | Power distribution network electric power electric transformer and its control method based on MMC |
| CN110442042A (en) * | 2019-08-13 | 2019-11-12 | 华北电力大学 | Electric car accesses electric power electric transformer number physical mixed real-time emulation system |
-
2020
- 2020-01-22 CN CN202010074332.XA patent/CN111244980B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109217687A (en) * | 2018-08-24 | 2019-01-15 | 南京理工大学 | Power distribution network electric power electric transformer and its control method based on MMC |
| CN110442042A (en) * | 2019-08-13 | 2019-11-12 | 华北电力大学 | Electric car accesses electric power electric transformer number physical mixed real-time emulation system |
Non-Patent Citations (1)
| Title |
|---|
| 陈璐瑶."基于MMC的电力电子配电变压器仿真研究".《中国优秀硕士学位论文全文数据库工程科技Ⅱ辑》.2017,第C042-816页. * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111244980A (en) | 2020-06-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111244980B (en) | Nonlinear control method of power electronic transformer based on MMC structure | |
| Wang et al. | Circulating current suppression for MMC-HVDC under unbalanced grid conditions | |
| CN109446653B (en) | Modeling method of mixed MMC small-signal model of mixed MMC state space model | |
| Singh et al. | A review of active filters for power quality improvement | |
| Chen et al. | A minimal harmonic controller for a STATCOM | |
| CN110868082B (en) | MMC-PET control method for supplying power to passive network based on power grid voltage fault | |
| Haque et al. | A UPFC for voltage regulation in LV distribution feeders with a DC-link ripple voltage suppression technique | |
| Zhou et al. | Adaptive DC-link voltage control for shunt active power filters based on model predictive control | |
| CN113595123A (en) | High-frequency impedance calculation method and device of modular multilevel converter | |
| CN110676850B (en) | Split capacitor direct-current voltage balancing method and system of three-phase four-wire three-leg STATCOM | |
| CN113452273B (en) | MMC four-layer structure submodule capacitor voltage balance control method | |
| CN108574295B (en) | MMC control method under unbalanced power grid voltage based on Lyapunov function | |
| CN111030131A (en) | MMC-STATCOM circulating current suppression device based on negative sequence virtual impedance | |
| Chihab et al. | Adaptive non-linear control of three-phase four-wire Shunt active power filters for unbalanced and nonlinear loads. | |
| CN115395809A (en) | MMC adaptive phase power balance control method and system | |
| CN111969643B (en) | Differential flat control method for MMC-HVDC (multi-media voltage direct current) supplying power to passive network under asymmetric fault | |
| CN114583706A (en) | Direct-current power distribution system for treating low voltage at tail end | |
| Marzouki et al. | Sensorless nonlinear control for a three-phase PWM AC-DC converter | |
| Qiu et al. | A dual closed-loop control strategy research based on sliding mode control for vienna rectifier | |
| Saralaya et al. | An improved voltage controller for distribution static compensator | |
| He et al. | Control strategy of high-performance active rectifier using modular multilevel converter without DC-link voltage sensors | |
| Zhang et al. | Improved quasi-PCI control strategy of inverter with unbalanced load | |
| Yang et al. | The State-Space Modeling and Nonlinear Control Strategies of Multilevel DSTATCOM | |
| Pote et al. | Analysis of T-STATCOM-6, 12, 48 Pulse | |
| JP7418576B2 (en) | BUS voltage balance adjustment method for power converter, power converter, storage medium and electronic device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |