CN112886828B - Power grid simulator topological structure and control method thereof - Google Patents
Power grid simulator topological structure and control method thereof Download PDFInfo
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- CN112886828B CN112886828B CN202110045176.9A CN202110045176A CN112886828B CN 112886828 B CN112886828 B CN 112886828B CN 202110045176 A CN202110045176 A CN 202110045176A CN 112886828 B CN112886828 B CN 112886828B
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- 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
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- 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
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
- H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
- H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
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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
- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The invention discloses a topological structure of a power grid simulator and a control method thereof. The topological structure comprises A, B, C three-phase, A, B, C three-phase LC filter, A, B, C three-phase transformer and load which are identical in structure. The simulator can operate in four quadrants, realizes the feedback of electric energy to a power grid, can provide three-phase power grid voltage output and simulate various power grid fault conditions of power grid such as voltage drop, frequency offset, three-phase imbalance, harmonic distortion and the like. On the design controller level, the control mode of the power grid simulator is divided into fundamental wave control and harmonic wave control, namely a low-frequency large-capacity module and a high-frequency small-capacity module are respectively controlled. In addition, a direct current side voltage follow-up control strategy is provided to solve the problem of power mismatch among modules.
Description
Technical Field
The invention belongs to the field of power electronic converters and control thereof, and particularly relates to a topological structure of a power grid simulator and a control method thereof.
Background
In order to grid-connect a distributed power generation system such as photovoltaic and wind power, the power grid adaptability test needs to be carried out before grid connection, but the power grid is a huge system, so that the operation is difficult to carry out when the power grid adaptability test is carried out. And the main role of the grid is to provide standard three-phase sinusoidal voltage to the consumer, various forms of grid faults are not common. Therefore, special equipment is needed to simulate the grid fault, and the distributed power generation system is tested. The power grid simulator has the function of simulating and outputting various faults of a power grid, not only can output normal power grid voltage, but also can simulate common faults such as voltage drop, three-phase imbalance, frequency offset, harmonic contained voltage and the like. And four-quadrant operation is to be achieved so that energy flows in both directions. With the scale of distributed power generation systems, the requirements for power and functions of grid simulators are also increasing. The deep research on the topological structure and the control strategy of the power grid simulator has very important significance and value on the adaptability test of the distributed power system.
The topological structure of the existing power grid simulator mainly adopts a front-stage uncontrollable rectification structure and a rear-stage three-phase PWM inversion structure, but the topological structure can not realize four-quadrant operation, is only specific to a medium-low voltage small-capacity system, and is not suitable for a large-capacity system. At present, a power grid simulator control strategy mainly comprises proportional-integral control, repetitive control, sliding mode variable control and the like, but a proportional-integral controller can only perform no-difference tracking on the amplitude of a power grid, and the tracking of given voltage has the problems of static difference, delay, oscillation and the like; the repetitive control has good steady-state output characteristics and robustness but has the problems of output delay of one fundamental wave period and poor dynamic performance; the sliding mode variable structure is nonlinear control, and has on and off control characteristics, so that a phenomenon of buffeting exists.
Disclosure of Invention
The invention aims to provide a power grid simulator topological structure and a control method thereof, aiming at the problems in the prior art.
The technical solution for realizing the purpose of the invention is as follows: a power grid simulator topology, the topology comprising: A. b, C three-phase, A, B, C three-phase LC filter, A, B, C three-phase transformer, and load; A. b, C three phases respectively output fundamental wave, low harmonic wave and high harmonic wave, and then are respectively connected with a load through a A, B, C three-phase LC filter and a A, B, C three-phase transformer in sequence.
Further, the A, B, C three phases have the same structure, and each phase comprises a fundamental wave and low-frequency large-capacity converter module and a high-frequency small-capacity converter module;
the fundamental wave and low-frequency large-capacity converter module is used for outputting fundamental waves and low-order harmonics;
and the high-frequency small-capacity converter module is used for outputting higher harmonics.
Furthermore, the fundamental wave and low-frequency large-capacity converter module comprises n first gain follow-up feedback modules and n first sectional wide-gain inversion modules;
the high-frequency small-capacity converter module comprises n second gain follow-up feedback modules and n second sectional type wide-gain inversion modules, wherein n is more than or equal to 1;
the output end of the first gain follow-up feedback module is connected with the first sectional type wide gain inversion module in a one-to-one corresponding way, and the output end of the second gain follow-up feedback module is connected with the second sectional type wide gain inversion module in a one-to-one corresponding way; the n first sectional type wide gain inversion modules are sequentially cascaded, and the n second sectional type wide gain inversion modules are sequentially cascaded; meanwhile, a first second sectional type wide gain inversion module and an nth first sectional type wide gain inversion module which are arranged in sequence are cascaded, the output end of the first sectional type wide gain inversion module which is arranged in sequence is connected with an A-phase or B-phase or C-phase LC filter, and the LC filter is connected with an A-phase or B-phase or C-phase transformer; A. b, C the n second sectional wide gain inversion modules in sequence are cascaded; wherein i is more than or equal to 1 and less than or equal to n.
Furthermore, the hardware topology structure of the gain follow-up feedback module is a three-phase pwm rectifier; the hardware topological structure of the sectional type wide-gain inversion module is an H-bridge inverter.
Further, the capacities of the fundamental wave and low frequency large-capacity converter module and the high frequency small-capacity converter module are selected as follows:
defining fundamental wave capacity as reference value 1, and obtaining harmonic wave capacity per unit value as S h ＝1.15-S(T os ) Where S (T) is a function of the fundamental output power over time, T os Is the overshoot time of the total power output.
Furthermore, the method comprises the steps of voltage outer loop control, current inner loop control, modulation wave distribution of a sectional type wide gain inversion module and direct current side voltage follow-up control of a gain follow-up feedback module; wherein the content of the first and second substances,
the voltage outer ring control of the sectional type wide-gain inversion module specifically comprises the following steps: a, B, C three-phase voltage is sampled to obtain phase voltage U A 、U B 、U C Phase voltage U A 、U B 、U C Obtaining U after abc _ dq coordinate transformation α 、U β A, B, C three-phase U A 、U B 、U C Voltage command value U of Aref 、U Bref 、U Cref Obtaining a voltage instruction U of a dq axis after abc _ dq coordinate transformation αref And U βref Will U is αref And U α Obtaining an inner ring d-axis current reference signal I through a PR controller after difference making αref Will U is βref And U β Obtaining an inner ring q-axis current reference signal I through a PR controller after difference making βref ；
The sectional type wide-gain inversion module current inner loop control specifically comprises the following steps: for A, B, C three-phase currentObtaining phase current I after sampling A 、I B 、I C Of phase current I A 、I B 、I C Obtaining I after the coordinate transformation of abc _ dq α 、I β Is shown by αref And I α Obtaining a d-axis modulated wave signal U through a PR controller after difference making αr Is shown by βref And I β Obtaining a q-axis modulated wave signal U through a PR controller after difference making βr Modulating the wave signal U with d-axis αr And q-axis modulated wave signal U βr Obtaining A, B, C three-phase modulating wave signal U after reverse Clack conversion a 、U b 、U c ；
The distribution of the modulation wave of the sectional type wide-gain inversion module is as follows: a, B, C three-phase modulated wave signal U a 、U b 、U c Obtaining U after Fourier transform a 、U b 、U c Fundamental component U of af 、U bf 、U cf A fundamental component U af 、U bf 、U cf As a modulated wave of A, B, C three-phase fundamental wave and low-frequency large-capacity converter module, U is set a -U af 、U b -U bf 、U c -U cf The modulation wave is used as an A, B, C three-phase high-frequency small-capacity converter module;
the gain follow-up feedback module direct-current side voltage follow-up control specifically comprises the following steps: voltage v at the DC side dc1a ...v dcna And the average value sigma v of all the modules of the system on the DC side voltage dcj The/3 n is compared, after the obtained error passes through the PI controller, the adjustment quantity of the output direct current side voltage is differed with the current direct current side voltage, and a new module direct current side voltage reference value v is generated * dc1a ...v * dcna Will modulate the wave v r1a ...v rna Divided by this value to obtain the control modulation ratio m 1a ...m na The output voltage proportion of the module with higher power is increased, and the power of each module is matched.
Compared with the prior art, the invention has the following remarkable advantages: aiming at the problem that the target performances of high capacity, high voltage dynamic response rate, high response precision, high reliability and the like of the current large-megawatt power grid simulator are difficult to consider, the invention provides a combined topological structure which can reasonably optimize and decompose the overall performance index to a subsystem, and avoids the bottleneck problem caused by excessive excavation of the performance of a single topological structure. Based on the thought, a power grid simulator topological structure with a fundamental wave and low-frequency large-capacity converter module and a high-frequency small-capacity converter module connected in series is provided, a sectional type wide-gain inversion module modulated wave distribution control strategy and a gain follow-up feedback module direct-current side voltage follow-up control strategy which correspond to the power grid simulator topological structure are provided, and a capacity matching principle of the low-frequency large-capacity converter module and the high-frequency small-capacity converter module is provided. The cost is reduced, the implementation complexity and the reliability risk are reduced, and meanwhile, a further breakthrough of the voltage dynamic response performance of the large-megawatt power grid simulator is obtained.
The present invention is described in further detail below with reference to the attached drawing figures.
Drawings
Fig. 1 is a schematic diagram of a topology of a power grid simulator in one embodiment.
Fig. 2 is a block diagram of voltage outer loop control, current inner loop control, and modulation wave distribution control of the topology of the grid simulator in one embodiment.
Fig. 3 is a block diagram of dc side voltage follow-up control of a topology of a grid simulator in an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In one embodiment, in conjunction with fig. 1, there is provided a grid simulator topology comprising: A. b, C three-phase, A, B, C three-phase LC filter, A, B, C three-phase transformer, and load; A. b, C three phases respectively output fundamental wave, low order harmonic and higher harmonic, and then are respectively connected with a load through a A, B, C three-phase LC filter and a A, B, C three-phase transformer in sequence.
The whole system is broken down into two parts: the topological structure comprises a fundamental wave rectifier module, a harmonic wave rectifier module, a fundamental wave inverter module, a harmonic wave inverter module, a filter and a fundamental wave harmonic wave connecting unit, wherein the fundamental wave rectifier module and the harmonic wave rectifier module adopt gain follow-up feedback modules and can generate respective required direct current voltages; the filter adopts an LC filter circuit; the fundamental wave harmonic wave connection unit adopts the transformer, not only plays a role in connecting fundamental wave harmonic waves, but also can play a role in isolating, and prevents the direct current side from generating a short circuit phenomenon.
Further, in one embodiment, the A, B, C three phases have the same structure, and each phase comprises a fundamental wave and low-frequency large-capacity converter module and a high-frequency small-capacity converter module;
the fundamental wave and low-frequency large-capacity converter module is used for outputting fundamental waves and low-order harmonics;
and the high-frequency small-capacity converter module is used for outputting higher harmonics.
Further, in one embodiment, the fundamental wave and low frequency large capacity converter module of phase a includes n first gain follow-up feedback modules a a1 ～A an N first segmented wide-gain inverter modules H aa1 ～H aan
The high-frequency small-capacity converter module comprises n second gain follow-up feedback modules A b1 ～A bn N second segmented wide gain inverter modules H ab1 ～H abn Wherein n is more than or equal to 1;
the first gain follow-up feedback module A ai Output end and first sectional type wide gain inversion module H aai One-to-one connection, second gain follow-up feedback module A bi And a second sectional wide gain inversion module H abi Connecting in a one-to-one correspondence manner; n first sectional type wide gain inversion modules H aai N second sectional type wide gain inversion modules H cascaded in sequence abi Sequentially cascading; at the same time, the first and second sectional wide-gain inversion modules H are arranged in sequence ab1 And n isFirst sectional type wide gain inversion module H aan Cascaded, sequentially arranged first segmented wide-gain inversion module H aa1 Is connected with an a-phase or B-phase or C-phase LC filter, which is then connected with an a-phase or B-phase or C-phase transformer a 1; A. b, C n-th second segmented wide-gain inversion module H in sequence in three phases abn Phase cascading; wherein i is more than or equal to 1 and less than or equal to n.
Further, in one embodiment, the B-phase fundamental wave and low-frequency bulk transformer module includes n first gain follow-up feedback modules B a1 ～B an N first segmented wide-gain inverter modules H ba1 ～H ban ；
The high-frequency small-capacity converter module comprises n second gain follow-up feedback modules B b1 ～B bn N second segmented wide gain inverter modules H bb1 ～H bbn Wherein n is more than or equal to 1;
the first gain follow-up feedback module B ai Output end and first sectional type wide gain inversion module H bai One-to-one connection, second gain follow-up feedback module B bi And a second sectional wide gain inversion module H bbi Connecting in a one-to-one correspondence manner; n first sectional type wide gain inversion modules H bai N second sectional wide gain inversion modules H cascaded in sequence bbi Sequentially cascading; at the same time, the first and second sectional wide-gain inversion modules H are arranged in sequence bb1 And the nth first segmented wide-gain inversion module H ban Cascaded, sequentially arranged first segmented wide-gain inversion module H ba1 Is connected with an a-phase or B-phase or C-phase LC filter, which is then connected with an a-phase or B-phase or C-phase transformer B1; A. b, C n-th second segmented wide-gain inversion module H in sequence in three phases bbn Phase cascading; wherein i is more than or equal to 1 and less than or equal to n.
Further, in one embodiment, the C-phase fundamental wave and low-frequency bulk transformer module includes n first gain follow-up feedback modules C a1 ～C an N number of the firstA segmentation wide gain contravariant module H ca1 ～H can ；
The high-frequency small-capacity converter module comprises n second gain follow-up feedback modules C b1 ～C bn N second segmented wide gain inverter modules H cb1 ～H cbn Wherein n is more than or equal to 1;
the first gain follow-up feedback module C ai Output end and first sectional type wide gain inversion module H cai One-to-one connection, second gain follow-up feedback module C bi And a second sectional wide gain inversion module H cbi Connecting in a one-to-one correspondence manner; n first sectional type wide gain inversion modules H cai N second sectional wide gain inversion modules H cascaded in sequence cbi Sequentially cascading; at the same time, the first and second sectional wide-gain inversion modules H are arranged in sequence cb1 And the nth first segmented wide-gain inversion module H can Cascaded, sequentially arranged first segmented wide-gain inversion module H ca1 Is connected with an a-phase or B-phase or C-phase LC filter, which is then connected with an a-phase or B-phase or C-phase transformer C1; A. b, C n-th second segmented wide-gain inversion module H in sequence in three phases cbn Phase cascading; wherein i is more than or equal to 1 and less than or equal to n.
Further, in one embodiment, the hardware topology of the gain follow-up feedback module is a three-phase pwm rectifier; the hardware topological structure of the sectional type wide-gain inversion module is an H-bridge inverter.
Further, in one embodiment, the capacities of the fundamental wave and low frequency large-capacity converter module and the high frequency small-capacity converter module are selected as follows:
selecting different capacities, generally, the total overshoot does not exceed 15% of a steady state value, and the principle of minimum effective value is followed, namely, the fundamental wave is designed according to the control parameters of an optimal overshoot-free system, and the overshoot of a harmonic part is 15%;
defining fundamental wave capacity as reference value 1, and obtaining harmonic wave capacity per unit value as S h ＝1.15-S(T os ) Where S (T) is a function of the fundamental output power over time, T os Is the overshoot time of the total power output.
In one embodiment, a control method for the power grid simulator topology is provided, and the method includes a segmented wide-gain inversion module voltage outer loop control, a current inner loop control, a modulation wave distribution, and a gain follow-up feedback module direct-current side voltage follow-up control; wherein, the voltage outer loop control, the current inner loop control and the modulation wave distribution are a sectional wide gain inversion module control strategy, as shown in fig. 2; the dc side voltage follow-up control is a gain follow-up feedback module control strategy, as shown in fig. 3.
The voltage outer ring control of the sectional type wide-gain inversion module specifically comprises the following steps: line voltage U after sampling line voltage of A, B, C three phases AB 、U BC And U CA According to the following formula:
phase voltage U is obtained through calculation A 、U B 、U C Phase voltage U A 、U B 、U C Obtaining U after converting abc _ dq coordinates α 、U β A, B, C three-phase U A 、U B 、U C Voltage command value U of Aref 、U Bref 、U Cref Obtaining a voltage instruction U of a dq axis after abc _ dq coordinate transformation αref And U βref Will U is αref And U α Obtaining an inner ring d-axis current reference signal I through a PR controller after difference making αref Will U is βref And U β Obtaining an inner ring q-axis current reference signal I through a PR controller after difference making βref ；
The segmented wide-gain inversion module current inner loop control specifically comprises the following steps: the current of A, B, C three phases is sampled to obtain phase current I A 、I B 、I C Of phase current I A 、I B 、I C Obtaining I after the coordinate transformation of abc _ dq α 、I β Is shown by αref And I α Obtaining a d-axis modulated wave signal U through a PR controller after difference making αr Is shown by βref And I β Obtaining a q-axis modulated wave signal U through a PR controller after difference making βr Modulating the wave signal U with d-axis αr And q-axis modulated wave signal U βr Obtaining A, B, C three-phase modulating wave signal U after reverse Clack conversion a 、U b 、U c ；
The distribution of the modulation wave of the sectional type wide-gain inversion module is as follows: a, B, C three-phase modulated wave signal U a 、U b 、U c Obtaining U after Fourier transform a 、U b 、U c Fundamental component U of af 、U bf 、U cf A fundamental component U af 、U bf 、U cf As a modulated wave of A, B, C three-phase fundamental wave and low-frequency large-capacity converter module, U is set a -U af 、U b -U bf 、U c -U cf A, B, C three-phase high-frequency small-capacity converter module;
the gain follow-up feedback module direct-current side voltage follow-up control specifically comprises the following steps: voltage v at the DC side dc1a ...v dcna And the average value sigma v of all the modules of the system on the DC side voltage dcj The/3 n is compared, after the obtained error passes through the PI controller, the adjustment quantity of the output direct current side voltage is differed with the current direct current side voltage, and a new module direct current side voltage reference value v is generated * dc1a ...v * dcna Will modulate the wave v r1a ...v rna Divided by this value to obtain the control modulation ratio m 1a ...m na The output voltage proportion of the module with higher power is increased, and the power of each module is matched.
In conclusion, the simulator can operate in four quadrants, realizes the feedback of electric energy to a power grid, can provide three-phase power grid voltage output and simulate various power grid fault conditions of power grid such as voltage drop, frequency offset, three-phase imbalance, harmonic distortion and the like. On the design controller level, the control mode of the power grid simulator is divided into fundamental wave control and harmonic wave control, namely a low-frequency large-capacity module and a high-frequency small-capacity module are respectively controlled. In addition, a direct current side voltage follow-up control strategy is provided to solve the problem of power mismatch among modules.
The embodiments described above are described to facilitate one of ordinary skill in the art to understand and use the invention patent. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (3)
1. A grid simulator topology, the topology comprising: A. b, C three-phase, A, B, C three-phase LC filter, A, B, C three-phase transformer, and load; A. b, C three phases respectively output fundamental waves, low harmonics and high harmonics, and then are respectively connected with a load through a A, B, C three-phase LC filter and a A, B, C three-phase transformer in sequence;
the A, B, C three phases have the same structure, and each phase comprises a fundamental wave and low-frequency large-capacity converter module and a high-frequency small-capacity converter module;
the fundamental wave and low-frequency large-capacity converter module is used for outputting fundamental waves and low-order harmonics;
the high-frequency small-capacity converter module is used for outputting higher harmonics;
the fundamental wave and low frequency large capacity converter module comprises n first gain follow-up feedback modules (A) a1 ～A an Or B a1 ～B an Or C a1 ～C an ) N first segmented wide gain inverter modules (H) aa1 ～H aan Or H ba1 ～H ban Or H ca1 ～H can )；
The high frequency small capacity converter module includes n second gain follow-up feedback modules (A) b1 ～A bn Or B b1 ～B bn Or C b1 ～C bn ) N second segmented wide gain inverter modules (H) ab1 ～H abn Or H bb1 ～H bbn Or H cb1 ～H cbn ) Wherein n is more than or equal to 1;
the first gain follow-up feedback module (A) ai Or B ai Or C ai ) And a first segmented wide gain inverter module (H) aai Or H bai Or H cai ) One-to-one connection, second gain follow-up feedback module (A) bi Or B bi Or C bi ) And a second sectional wide gain inversion module (H) abi Or H bbi Or H cbi ) Connecting in a one-to-one correspondence manner; n first segmented wide gain inversion modules (H) aai Or H bai Or H cai ) N second segmented wide gain inversion modules (H) cascaded in sequence abi Or H bbi Or H cbi ) Sequentially cascading; at the same time, the first and second segmented wide gain inversion modules (H) are arranged in sequence ab1 Or H bb1 Or H cb1 ) And the nth first segmented wide gain inversion module (H) aan Or H ban Or H can ) Cascaded, sequenced first one of the first segmented wide gain inverter modules (H) aa1 Or H ba1 Or H ca1 ) Is connected to an a-phase or B-phase or C-phase LC filter, which is then connected to an a-phase or B-phase or C-phase transformer (a1 or B1 or C1); A. b, C n-th segmented wide-gain inversion module in sequence in three phases abn Or H bbn Or H cbn ) Phase cascading; wherein i is more than or equal to 1 and less than or equal to n;
the control method based on the topological structure of the power grid simulator comprises the steps of voltage outer ring control, current inner ring control, modulation wave distribution and gain follow-up type feedback module direct-current side voltage follow-up control of a sectional type wide gain inversion module; wherein the content of the first and second substances,
the voltage outer ring control of the sectional type wide-gain inversion module specifically comprises the following steps: a, B, C three-phase voltage is sampled to obtain phase voltage U A 、U B 、U C Phase voltage U A 、U B 、U C Obtaining U after converting abc _ dq coordinates α 、U β A, B, C three-phase U A 、U B 、U C Voltage command value U of Aref 、U Bref 、U Cref Obtaining a voltage instruction U of a dq axis after abc _ dq coordinate transformation αref And U βref Will U is αref And U α Obtaining an inner ring d-axis current reference signal I through a PR controller after difference making αref Will U is βref And U β Obtaining an inner ring q-axis current reference signal I through a PR controller after difference making βref ；
The segmented wide-gain inversion module current inner loop control specifically comprises the following steps: the current of A, B, C three phases is sampled to obtain phase current I A 、I B 、I C Of phase current I A 、I B 、I C Obtaining I after abc _ dq coordinate transformation α 、I β Is shown by αref And I α Obtaining a d-axis modulated wave signal U through a PR controller after difference making αr Is shown by βref And I β Obtaining a q-axis modulated wave signal U through a PR controller after difference making βr Modulating the wave signal U with d-axis αr And q-axis modulated wave signal U βr Obtaining A, B, C three-phase modulating wave signal U after reverse Clack conversion a 、U b 、U c ；
The distribution of the modulation wave of the sectional type wide-gain inversion module is as follows: a, B, C three-phase modulated wave signal U a 、U b 、U c Obtaining U after Fourier transform a 、U b 、U c Fundamental component U of af 、U bf 、U cf A fundamental component U af 、U bf 、U cf As a modulated wave of A, B, C three-phase fundamental wave and low-frequency large-capacity converter module, U is set a -U af 、U b -U bf 、U c -U cf The modulation wave is used as an A, B, C three-phase high-frequency small-capacity converter module;
the gain follow-up feedback module direct-current side voltage follow-up control specifically comprises the following steps: voltage v at the DC side dc1a ...v dcna And the average value sigma v of all the modules of the system on the DC side voltage dcj The/3 n is compared, after the obtained error passes through the PI controller, the adjustment quantity of the output direct current side voltage is differed with the current direct current side voltage, and a new module direct current side voltage reference value v is generated * dc1a ...v * dcna Will modulate the wave v r1a ...v rna And v * dc1a ...v * dcna Dividing to obtain a control modulation ratio m 1a ...m na The output voltage proportion of the module with higher power is increased, and the power of each module is matched.
2. The grid simulator topology of claim 1, wherein the gain-follower-type feedback module has a hardware topology that is a three-phase pwm rectifier; the hardware topological structure of the sectional type wide-gain inversion module is an H-bridge inverter.
3. The grid simulator topology of claim 1, wherein the fundamental and low frequency large capacity converter modules and the high frequency small capacity converter modules have capacities selected from the group consisting of:
defining fundamental wave capacity as reference value 1, and obtaining harmonic wave capacity per unit value as S h ＝1.15-S(T os ) Where S (T) is a function of the fundamental output power over time, T os Is the overshoot time of the total power output.
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