A three-port power router topology and control method for high-reliability power supply

Abstract

The present invention belongs to the technical field of power electronic converters, and discloses a three-port power router topology and control method for high-reliability power supply. The topology structure includes three connected reactors L, a chain SVG, a three-phase isolation transformer, a three-phase LC filter, a three-phase three-port H-bridge inverter circuit and an energy storage DC port. The present invention forms a three-port converter topology with high-voltage AC, low-voltage AC and energy storage DC through the fusion of multi-form high and low voltage conversion topologies. Its control method can realize the reactive power compensation function of the chain SVG; the three-phase three-port H-bridge inverter circuit can maintain the voltage stability of the 380V low-voltage AC bus and provide active power support for the chain SVG; when a fault such as a grid voltage drop occurs in the 10kV AC feeder, the fault can be isolated through the chain SVG, thereby realizing high-reliability power supply of the 380V low-voltage AC bus.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronic converters, and in particular relates to a three-port power router topology with high-reliability power supply and a control method. Background Art

[0002] Static VAR generators (SVG) stabilize the voltage at the connection point, enhance the system voltage stability, improve the system load capacity, or provide support for the voltage of key nodes of the system to enhance the system stability limit by absorbing or emitting continuously adjustable reactive power. However, traditional SVGs only have reactive power exchange capabilities, but not active power exchange capabilities. In order to achieve better results, SVGs are sometimes required to have a certain ability to exchange active power with the power grid to achieve the purpose of suppressing the power pulsation of renewable energy generation, shaving peaks and filling valleys, compensating for circuit resistive voltage drops, damping the oscillation of the system, and extending the support time of the power grid under fault conditions.

[0003] The PCS has four-quadrant operation function, can output or absorb reactive and active power at the same time, and has frequency and voltage regulation functions. The reactive power compensation technology based on energy storage has the advantages of fast response speed, continuous adjustment, and controllable scale, and is suitable for new power systems with a high proportion of new energy and high power electronics.

[0004] Energy storage SVG combines energy storage technology with reactive power compensation technology, taking advantage of their strengths and avoiding their weaknesses to achieve functional complementarity. The increase in energy storage enables it to have fast and stable dynamic reactive power support capabilities, and to quickly and reasonably compensate for reactive and active power when an AC power grid fails, providing the greatest support for the grid voltage, which is of great significance for improving the safe and reliable operation of AC / DC hybrid power grids.

[0005] Through the above analysis, the problems and defects of the prior art are as follows:

[0006] Currently, SVG only has reactive power exchange capability but not active power exchange capability. The problem of how to quickly and reasonably compensate for AC power grid failure remains to be solved. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a three-port power router topology with high-reliability power supply and a control method.

[0008] The present invention is implemented in this way: a low-switching-frequency chain SVG is connected to the 10kV AC feeder of the power grid and realizes the reactive current regulation function; a high-switching-frequency three-phase three-port H-bridge inverter circuit maintains the 380V low-voltage AC bus voltage stability and provides active support for the chain SVG; the DC port of the three-phase three-port H-bridge inverter circuit is connected to the energy storage device, forming a three-port hybrid power distribution system of high-voltage AC, low-voltage AC, and energy storage DC; when a high-voltage 10kV AC port fails, the chain SVG can isolate the fault, thereby realizing a highly reliable power supply of the 380V low-voltage AC bus, and then sensitive loads can be connected. The present invention adopts a cascaded low-switching-frequency topology and a high-switching-frequency topology in a mixed connection, which has a simple structure, is relatively easy to control, and has flexible and diverse power regulation functions.

[0009] The three-port power router topology structure with high-reliability power supply includes: three connected reactors L, a chain SVG, a three-phase isolation transformer, a three-phase LC filter, a three-phase three-port H-bridge inverter circuit and an energy storage DC port;

[0010] One end of the connection reactor L is connected to the 10kV AC feeder, and the other end is connected to the chain SVG;

[0011] The chain SVG includes three cascaded H-bridge converters HJ (J=A, B, C, representing three phases A, B, and C);

[0012] The cascaded H-bridge converter includes n H-bridge circuits HJ1 to HJn, where n can be comprehensively selected based on specific application scenarios, cost, and space constraints;

[0013] The H-bridge circuit includes two bridge arms including two IGBTs and a DC side capacitor C Hd ;

[0014] In the chain SVG, one end of the AC port of HJ1 is connected to the 10kV AC feeder of the power grid via the connecting reactor L, and the other end is connected to the AC port of HJ2; one end of the AC port of HJ2 is connected to the AC port of HJ1, and the other end is connected to the AC port of HJ3, and so on for the connection mode of the AC ports of HJ3 to HJn1; one end of the AC port of HJn is connected to the AC port of HJn1, and the other end is connected to the primary side of the three-phase isolation transformer;

[0015] The primary side of the three-phase isolation transformer is connected to one end of the HJn AC port, and the secondary side is connected to the 380V low-voltage AC bus;

[0016] One end of the 380V low-voltage AC bus is connected to the secondary side of the three-phase isolation transformer, and the other end is connected to the three-phase LC filter. At the same time, the AC bus can supply power to sensitive loads;

[0017] The three-phase LC filter, filter capacitor C 1 Connected in parallel with the 380V low voltage AC bus, the filter inductor L 1 connected in series with a three-phase three-port H-bridge inverter circuit;

[0018] The three-phase three-port H-bridge inverter circuit includes six IGBT switches (Q 1 ~Q 6 );Switch tube Q 1 With Q 2 Forming the A phase bridge arm, Q 1 The source and Q 2 The drain and filter inductor L 1 Connected, Q 1 The drain of the energy storage device is connected to the positive terminal of the DC port, Q 2 The source of is connected to the negative pole of the energy storage DC port; the switch tube Q 3 With Q 4 Forming the B phase bridge arm, Q 3 The source and Q 4 The drain and filter inductor L 1 Connected, Q 3 The drain of the energy storage device is connected to the positive terminal of the DC port, Q 4 The source of is connected to the negative pole of the energy storage DC port; the switch tube Q 5 With Q 6 Forming the C phase bridge arm, Q 5 The source and Q 6 The drain and filter inductor L 1 Connected, Q 5 The drain of the energy storage device is connected to the positive terminal of the DC port, Q 6 The source electrode is connected to the negative electrode of the energy storage DC port;

[0019] The DC side of the three-phase three-port H-bridge inverter circuit is connected to an energy storage DC port, which can be connected to a photovoltaic power generation system, a battery energy storage device, etc.

[0020] The chain SVG realizes reactive current control and fault isolation of the grid-connected port through the chain SVG control unit;

[0021] The chain SVG control unit generates a PWM signal to control each switch tube of the chain SVG by combining the three-phase voltage and three-phase current of the 10kV AC feeder and the DC voltage reference value of each H-bridge circuit of the chain SVG, using a phase-locked loop controller, DC voltage control, and AC current control;

[0022] The three-phase three-port H-bridge inverter circuit maintains the stability of the 380V low-voltage AC bus voltage through the three-phase three-port H-bridge inverter circuit control unit, and provides active support for the chain SVG;

[0023] The three-phase three-port H-bridge inverter circuit control unit generates a PWM signal to control the three-phase switch tube by combining the three-phase voltage of the low-voltage AC bus and the three-phase current of the three-phase three-port H-bridge inverter circuit, using a phase-locked loop controller, AC voltage control, and AC current control;

[0024] Further, the chained SVG control unit comprises:

[0025] The first instantaneous positive and negative sequence calculator is used to calculate the instantaneous positive and negative sequence of the 10kV AC feeder three-phase voltage to obtain the instantaneous three-phase positive and negative sequence voltage of the 10kV AC feeder;

[0026] A phase-locked loop controller is used to calculate the 10kV AC feeder voltage through phase-locking to obtain the phase of the two-phase synchronous rotating coordinate system;

[0027] The second instantaneous positive and negative sequence calculator is used to calculate the instantaneous three-phase positive and negative sequence current of the 10kV AC feeder line through the instantaneous positive and negative sequence calculation;

[0028] A first proportional-integral controller is used to obtain a value obtained by adding the average value of the DC voltage through proportional calculation and integral calculation as a positive-sequence active current reference value in a two-phase synchronous rotating coordinate system;

[0029] The second proportional integral controller is used for performing proportional calculation and integral calculation on the difference between the positive sequence active current reference value and the actual positive sequence active current value, and the sum of the values ​​obtained is used as the positive sequence active voltage reference value of the chain SVG;

[0030] A third proportional integral controller is used for performing proportional calculation and integral calculation on the difference between the positive sequence reactive current reference value and the actual value of the positive sequence reactive current, and the sum of the values ​​obtained is used as the chain SVG positive sequence reactive voltage reference value;

[0031] A first anti-Park controller is used to convert the positive sequence modulation voltage in the two-phase synchronous rotating coordinate system into a three-phase positive sequence modulation voltage reference value in the three-phase stationary coordinate system;

[0032] A fourth proportional integral controller is used for performing proportional calculation and integral calculation on the difference between the negative sequence active current reference value and the actual negative sequence active current value, and the sum of the values ​​obtained is used as the chain SVG negative sequence active voltage reference value;

[0033] A fifth proportional integral controller, used for performing proportional calculation and integral calculation on the difference between the negative-sequence reactive current reference value and the actual negative-sequence reactive current value, and adding the summed values ​​as the chain SVG negative-sequence reactive voltage reference value;

[0034] A second anti-Park controller is used to convert the negative sequence modulation voltage in the two-phase synchronous rotating coordinate system into a three-phase negative sequence modulation voltage reference value in the three-phase stationary coordinate system;

[0035] A first PWM generator, whose input is the sum of a chain SVG three-phase positive sequence modulation voltage reference value and a chain SVG three-phase negative sequence modulation voltage reference value, and whose output is a PWM driving signal of the chain SVG;

[0036] Further, the three-phase three-port H-bridge inverter circuit control unit includes:

[0037] The first Park controller is used to convert the three-phase voltage of the 380V low-voltage AC bus in the three-phase stationary coordinate system into the voltage in the two-phase synchronous rotating coordinate system;

[0038] A first low-pass filter, used for low-pass filtering the active voltage on the two-phase synchronous rotating coordinate system;

[0039] a sixth proportional-integral controller, configured to perform proportional calculation and integral calculation on the difference between the active voltage reference value and the actual active voltage value, and to obtain a value as the active voltage reference value of the three-phase three-port H-bridge inverter circuit;

[0040] A second low-pass filter is used to perform low-pass filtering on the reactive voltage on the two-phase synchronous rotating coordinate system;

[0041] A seventh proportional-integral controller, used for performing proportional calculation and integral calculation on the difference between the reactive voltage reference value and the actual reactive voltage value, and adding the summed values ​​to obtain the value as the reactive voltage reference value of the three-phase three-port H-bridge inverter circuit;

[0042] A third anti-Park controller, used for converting the modulation voltage in the two-phase synchronous rotating coordinate system into a three-phase modulation voltage reference value in the three-phase stationary coordinate system;

[0043] A second Park controller is used to convert the three-phase current of the three-phase three-port H-bridge inverter circuit in a three-phase stationary coordinate system into a current in a two-phase synchronous rotating coordinate system;

[0044] A third low-pass filter is used to perform low-pass filtering on the active current on the two-phase synchronous rotating coordinate system;

[0045] a fourth low-pass filter, for low-pass filtering the reactive current on the two-phase synchronous rotating coordinate system;

[0046] The first damping controller is used to convert the difference between the actual active current and the active current after low-pass filtering into a difference in high-order harmonic voltage;

[0047] The second damping controller is used to convert the difference between the actual reactive current and the reactive current after low-pass filtering into a difference in high-order harmonic voltage;

[0048] a fourth anti-Park controller, for converting a high-order harmonic voltage in a two-phase synchronous rotating coordinate system into a three-phase high-order harmonic voltage reference value in a three-phase stationary coordinate system;

[0049] The second PWM generator has an input of the difference between the three-phase modulation voltage reference value and the three-phase higher harmonic voltage reference value, and an output of the PWM drive signal of the three-phase three-port H-bridge inverter circuit;

[0050] Furthermore, the control method of the chained SVG comprises the following steps:

[0051] (1) Output voltage u for 10kV AC feeder of power grid sa 、u sb 、u sc Perform instantaneous positive and negative sequence calculations to obtain the positive and negative sequence three-phase voltage values ​​u sa p 、u sb p 、u sc p 、u sa n 、u sb n 、u sc n , and then perform Clark transformation on the positive and negative sequence three-phase voltage values ​​respectively to obtain the voltage u of the positive and negative sequence voltage in the two-phase stationary coordinate system sα p 、u sβ p 、u sα n 、u sβ n , and then transform it to the two-phase synchronous rotating coordinate system to obtain u sd p 、u sq p 、u sd n 、u sq n , for u sq p and u sq n The phase of the positive sequence voltage of the 10kV AC feeder line of the power grid can be obtained by using a synchronous rotating coordinate system phase-locked loop (SRFPLL). 1 t and negative sequence voltage phase ω 2 t;

[0052] (2) Output current i of 10kV AC feeder of power grid sa 、i sb 、i sc Perform instantaneous positive and negative sequence calculations to obtain the positive and negative sequence three-phase current values ​​i sa p 、i sb p 、i sc p 、i sa n 、i sb n 、i sc n , and then perform Park transformation on the positive and negative sequence three-phase current values ​​respectively to obtain the current i of the positive and negative sequence current in the two-phase synchronous rotating coordinate system sd p 、i sq p 、i sd n 、i sq n ;

[0053] (3) The sum of the DC side voltages of all H-bridge circuits in each phase of the chain SVG is U HdΣA , U HdΣB , U HdΣC Add them together and multiply by 1 / 3 to get the total DC voltage average value U HdΣ . Set the DC voltage reference value The total DC voltage average value U HdΣ Subtract, the difference is input into the voltage loop proportional integral controller, and the output is the d-axis positive sequence current reference value

[0054] (4) Set the d-axis positive sequence current reference value and d-axis positive sequence current i sd p Subtract the difference, and input the current loop proportional integral controller to convert the angular velocity ω, the reactor L and the q-axis positive sequence current i sq p The product of the positive sequence voltage u sd p Add and subtract the output value of the current loop proportional integral controller to obtain the d-axis positive sequence voltage reference value; set the q-axis positive sequence current reference value and the q-axis positive sequence current i sq p Subtract the difference, and input the current loop proportional integral controller to convert the q-axis positive sequence voltage u sq p Subtract the angular velocity ω, the reactor L and the d-axis positive sequence current i sd pThe product of , minus the output value of the current loop proportional integral controller, is used to obtain the q-axis positive sequence voltage reference value;

[0055] (5) Set the d-axis negative sequence current reference value and the d-axis negative sequence current i sd n Subtract the difference, and input the current loop proportional integral controller to convert the d-axis negative sequence voltage u sd n Subtract the angular velocity ω, the reactor L and the q-axis negative sequence current i sq n The product of the current loop proportional integral controller is subtracted to obtain the d-axis negative sequence voltage reference value; the q-axis negative sequence current reference value is set. and the q-axis negative sequence current i sq n Subtract the difference, and input the current loop proportional integral controller to convert the angular velocity ω, the reactor L and the d-axis negative sequence current i sd n The product of the q-axis negative sequence voltage u sq n Add and subtract the output value of the current loop proportional-integral controller to obtain the q-axis negative-sequence voltage reference value;

[0056] (6) The d-axis positive sequence voltage reference value, the q-axis positive sequence voltage reference value, the d-axis negative sequence voltage reference value, and the q-axis negative sequence voltage reference value are subjected to inverse PARK transformation to generate positive and negative sequence modulation voltages u sma p 、u smb p 、u smc p 、u sma n 、u smb n 、u smc n , the positive and negative sequence modulation voltages are added and input into the PWM generator to form the PWM signal g sax , g sbx , g scx , control each H-bridge module of the chained SVG;

[0057] Furthermore, the control method of the three-phase three-port H-bridge inverter circuit comprises the following steps:

[0058] (1) The three-phase voltage u on the AC side of the 380V low-voltage bus ia 、u ib 、u ic Perform Park transformation to obtain the voltage u in the two-phase synchronous rotating coordinate system id 、u iq, and filtered through a low-pass filter, setting the d and q axis voltage reference values ​​respectively

[0059] (2) d-axis and q-axis voltage reference values Respectively with u id 、u iq The filtered values ​​are subtracted, and the difference is input into the voltage loop proportional integral controller. The output value of the voltage loop proportional integral controller is subjected to inverse Park transformation to obtain u ima1 ,u imb1 ,u imc1 ;

[0060] (3) The three-phase current i on the AC side of the three-phase three-port H-bridge inverter circuit ia 、i ib 、i ic Perform Park transformation to obtain the current i in the two-phase synchronous rotating coordinate system id 、i iq ,i id 、i iq Subtract the values ​​from those after the low-pass filter to get the high-order harmonic current Δi id , Δi iq Δi id , Δi iq Multiply them by the damping coefficient K respectively, and perform inverse Park transformation to obtain the high-order harmonic voltage u ima2 ,u imb2 ,u imc2 ;

[0061] (4) will u ima1 ,u imb1 ,u imc1 With high-order harmonic voltage u ima2 ,u imb2 ,u imc2 Subtract to generate modulation voltage u ima ,u imb ,u imc And input PWM generator to form PWM signal g i1 ~g i6 , to control the three-phase three-port H-bridge inverter circuit.

[0062] Another object of the present invention is to provide a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the three-port power router topology control method with high-reliability power supply.

[0063] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to perform the steps of the topology control method of the three-port power router with high-reliability power supply.

[0064] Another object of the present invention is to provide an information data processing terminal, which is used to implement the three-port power router topology device with high-reliability power supply.

[0065] Another object of the present invention is to provide a control method for the chained SVG of the three-port power router topology, the control method for the chained SVG comprising the following steps:

[0066] (a) Calculate the instantaneous positive and negative sequence of the output voltage of the 10 kV AC feeder of the power grid, perform Clark transformation and transformation in the synchronous rotating coordinate system to obtain the voltage phase;

[0067] (b) Calculate the instantaneous positive and negative sequence of the output current of the 10 kV AC feeder of the power grid and perform Park transformation to obtain the current in the synchronous rotating coordinate system;

[0068] (c) Calculate the sum of the DC side voltages of all H-bridge circuits of each phase of the chain SVG and obtain the average value of the total DC voltage to set the current reference value;

[0069] (d) calculating the d-axis and q-axis positive and negative sequence voltage reference values ​​according to the current reference value and the actual current value;

[0070] (e) Perform inverse PARK transformation to generate positive and negative sequence modulation voltages, and control each H-bridge module of the chain SVG through a PWM generator.

[0071] The calculation of the positive and negative sequence voltages further includes using a synchronous rotating frame phase locked loop (SRFPLL) to obtain the phases of the positive and negative sequence voltages.

[0072] Calculating the total DC voltage average value further includes adding the DC side voltages of the H-bridges of each phase and multiplying the voltage by 1 / 3, and comparing the sum with a preset DC voltage reference value to generate a reference value of the d-axis positive sequence current.

[0073] The calculation of the d-axis and q-axis voltage reference values ​​further includes using a current loop proportional-integral controller to adjust the voltage error, and combining the angular velocity and the reactor parameters to obtain the final voltage reference value.

[0074] The generation of the positive and negative sequence modulation voltage further includes performing inverse PARK transformation on the positive and negative sequence voltage reference values ​​of the d-axis and the q-axis, respectively, and adding the results to the PWM generator to form a corresponding PWM signal.

[0075] Another object of the present invention is to provide a control method for a three-phase three-port H-bridge inverter circuit control unit based on the above-mentioned three-port power router topology, comprising the following steps:

[0076] (a) Perform Park transformation and filtering on the three-phase voltage on the AC side of the 380V low-voltage bus, and set the d-axis and q-axis voltage reference values;

[0077] (b) calculating the error based on the reference value and the filtered voltage value and inputting it into the voltage loop proportional integral controller;

[0078] (c) Perform Park transformation on the three-phase current on the AC side, calculate the high-order harmonic current, and multiply it by the damping coefficient;

[0079] (d) Subtract the voltage value output by the controller from the high-order harmonic voltage to generate a modulation voltage, and control the inverter circuit through the PWM generator.

[0080] In combination with the above technical solutions and the technical problems solved, please analyze the advantages and positive effects of the technical solutions to be protected by the present invention from the following aspects:

[0081] First, the present invention provides a three-port power router topology and control method with high-reliability power supply, which can adjust reactive current through low-switching frequency chain SVG, high-switching frequency three-phase three-port H-bridge inverter circuit to maintain 380V low-voltage AC bus voltage stability, and provide active support for chain SVG, the DC port of the three-phase three-port H-bridge inverter circuit is connected to the energy storage device, forming a three-port hybrid distribution system of high-voltage AC, low-voltage AC, and energy storage DC; when the high-voltage 10kV AC port fails, the chain SVG can isolate the fault, thereby achieving high-reliability power supply of the 380V low-voltage AC bus, and then sensitive loads can be connected. The present invention adopts a cascaded low-switching frequency topology and a high-switching frequency topology mixed connection, which has a simple structure, is relatively easy to control and has high flexibility, and has a wide range of application scenarios.

[0082] Second, the significant technical advances brought about by the chained SVG control method of the three-port power router proposed in the present invention include:

[0083] 1) Improve grid stability: Through accurate instantaneous positive and negative sequence calculation and transformation, this method can more effectively handle unbalanced loads in the grid, thereby improving the overall stability of the grid.

[0084] 2) Optimize voltage and current control: Using advanced voltage loop and current loop proportional-integral controllers, this method can more accurately control the output of the power router, ensuring higher energy conversion efficiency and power quality.

[0085] 3) Improve system response speed: Through the synchronous rotating coordinate system phase-locked loop (SRFPLL) and the efficient inverse transformation algorithm, this method can quickly respond to grid changes and provide faster regulation capabilities.

[0086] 4) Enhanced system flexibility: This method provides a more flexible power distribution and control strategy to adapt to different grid conditions and requirements by comprehensively considering the DC side voltage of all H-bridge circuits in each phase of the chain SVG.

[0087] 5) Improve fault tolerance: In the calculation of current and voltage reference values, the method takes into account the comprehensive control of positive and negative sequence currents and voltages, which enhances the system's fault tolerance and stability in the face of grid faults.

[0088] 6) System integration and cost optimization: This method integrates multiple control links of the power router, making the system more compact and reducing hardware costs and maintenance difficulties.

[0089] In summary, this control method not only improves the stability of the power grid and the power conversion efficiency, but also enhances the system's adaptability to power grid changes and fault tolerance, while optimizing the system's cost and maintenance requirements.

[0090] Third, the technical solution of the present invention fills the technical gap in the industry at home and abroad: the present invention is connected to the 10kV AC feeder of the power grid through a low switching frequency chain SVG, and realizes the reactive current regulation function; the high switching frequency three-phase three-port H-bridge inverter circuit maintains the stability of the 380V low-voltage AC bus voltage and provides active support for the chain SVG; the DC port of the three-phase three-port H-bridge inverter circuit is connected to the energy storage device, forming a three-port hybrid distribution system of high-voltage AC, low-voltage AC, and energy storage DC. The present invention adopts a cascaded low switching frequency topology and a high switching frequency topology, which has flexible and diverse power regulation functions and provides a new solution for the three-port power router.

[0091] The technical solution of the present invention solves a technical problem that people have been eager to solve but have never been successful: most of the current energy storage SVGs add energy storage devices to the DC side of each H-bridge circuit of the cascaded H-bridge circuit, and need to add corresponding DC-DC converters. Due to the large number of H-bridge circuits required, this solution is complex to control, has a large number of components, and is costly. How to reduce costs and simplify control is a technical difficulty that energy storage SVG needs to solve. The present invention connects the chain SVG to the AC side of the three-phase inverter circuit through an industrial frequency transformer, and introduces an energy storage port into the DC side of the three-phase inverter circuit to provide active support for the chain SVG and transmit active power to the power system. In comparison, the present invention has simpler control, fewer components, and lower costs, providing a new idea for energy storage STATCOM. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 It is a circuit topology diagram of a three-port power router device with high-reliability power supply provided by an embodiment of the present invention;

[0093] Figure 2 is a phase-locked loop control block diagram of a chained SVG control unit provided by an embodiment of the present invention;

[0094] Figure 3 is a control block diagram of a chained SVG control unit provided by an embodiment of the present invention;

[0095] Figure 4 It is a control block diagram of a three-phase three-port H-bridge inverter circuit control unit provided by an embodiment of the present invention;

[0096] Figure 5 is a reactive current waveform when the chain SVG provided in an embodiment of the present invention performs reactive power compensation;

[0097] Figure 6 is a low voltage AC bus phase voltage waveform provided by an embodiment of the present invention;

[0098] Figure 7 It is a voltage waveform of a 10 kV AC power grid when the voltage of the 10 kV AC power grid drops according to an embodiment of the present invention;

[0099] Figure 8 It is the reactive current waveform of the chain SVG when the voltage of the 10kV AC grid drops provided by the embodiment of the present invention;

[0100] Fig. 9 This is the phase voltage waveform of the low-voltage AC bus when the 10kV AC grid voltage drops according to the embodiment of the present invention.

[0101] In the figure: 1. 10kV AC feeder of the power grid; 2. Chain SVG; 3. Three-phase isolation transformer; 4. 380V low-voltage AC bus; 5. Sensitive charge; 6. Three-phase three-port H-bridge inverter circuit; 7. Energy storage DC port. DETAILED DESCRIPTION

[0102] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0103] like Figure 1As shown, the topological structure of the three-port power router with high-reliability power supply provided by the embodiment of the present invention includes: three connected reactors L, a chain SVG circuit, a three-phase isolation transformer, a three-phase LC filter, a three-phase three-port H-bridge inverter, a DC capacitor Cid, and an energy storage DC port UDC;

[0104] One end of the connection reactor L is connected to the 10kV AC feeder, and the other end is connected to the chain SVG;

[0105] The chain SVG includes three cascaded H-bridge converters HJ (J = A, B, C, representing the three phases A, B, and C); the cascaded H-bridge converter includes n H-bridge circuits HJ1 to HJn, where n can be comprehensively selected based on specific application scenarios, cost, and space constraints; the H-bridge circuit includes two bridge arms containing two IGBTs and a DC side capacitor C Hd ; One end of the AC port of HJ1 is connected to the 10kV AC feeder of the power grid via the connecting reactor L, and the other end is connected to the AC port of HJ2; one end of the AC port of HJ2 is connected to the AC port of HJ1, and the other end is connected to the AC port of HJ3, and so on for the connection mode of the AC ports of HJ3 to HJn1; one end of the AC port of HJn is connected to the AC port of HJn1, and the other end is connected to the primary side of the three-phase isolation transformer;

[0106] The primary side of the three-phase isolation transformer is connected to one end of the HJn AC port, and the secondary side is connected to the 380V low-voltage AC bus;

[0107] One end of the 380V low-voltage AC bus is connected to the secondary side of the three-phase isolation transformer, and the other end is connected to the three-phase LC filter. At the same time, the AC bus can supply power to sensitive loads;

[0108] In the three-phase LC filter, the filter capacitor C 1 Connected in parallel with the 380V low voltage AC bus, the filter inductor L 1 connected in series with a three-phase three-port H-bridge inverter circuit;

[0109] The three-phase three-port H-bridge inverter circuit includes six IGBT switches (Q 1 ~Q 6 );Switch tube Q 1 With Q 2 Forming the A phase bridge arm, Q 1 The source and Q 2 The drain and filter inductor L 1 Connected, Q 1 The drain of the energy storage device is connected to the positive terminal of the DC port, Q 2 The source of is connected to the negative pole of the energy storage DC port; the switch tube Q 3 With Q 4 Forming the B phase bridge arm, Q3 The source and Q 4 The drain and filter inductor L 1 Connected, Q 3 The drain of the energy storage device is connected to the positive terminal of the DC port, Q 4 The source of is connected to the negative pole of the energy storage DC port; the switch tube Q 5 With Q 6 Forming the C phase bridge arm, Q 5 The source and Q 6 The drain and filter inductor L 1 Connected, Q 5 The drain of the energy storage device is connected to the positive terminal of the DC port, Q 6 The source electrode is connected to the negative electrode of the energy storage DC port;

[0110] The DC side of the three-phase three-port H-bridge inverter circuit is connected to the energy storage DC port, which can be connected to a photovoltaic power generation system, a battery energy storage device, etc.

[0111] In the main circuit topology, the three-phase voltage of the 10kV AC feeder is: sa 、u sb 、u sc , the three-phase current is: i sa 、i sb 、i sc ; The DC voltage of the H-bridge circuit in the chain SVG is U Hd ; The three-phase voltage of 380V low-voltage AC bus is: u ia 、u ib 、u ic ; The three-phase current of the three-phase three-port H-bridge inverter circuit is: i ia 、i ib 、i ic ; The DC voltage of the energy storage DC port is U DC .

[0112] The three-port power router device topology structure with high-reliability power supply provided by the embodiment of the present invention realizes functions such as reactive power compensation, low-voltage AC bus voltage stability, fault isolation, etc. through the control of the chain SVG circuit control unit and the control method of the three-phase three-port H-bridge inverter circuit control unit during operation.

[0113] Figure 2 The present invention provides a chain type SVG control unit phase-locked loop control block diagram, comprising the following steps:

[0114] Output voltage u to the 10kV AC feeder of the power grid sa 、u sb 、u sc Perform instantaneous positive and negative sequence calculations to obtain the positive and negative sequence three-phase voltage values ​​u sa p 、usb p 、u sc p 、u sa n 、u sb n 、u sc n ;

[0115] Clark transformation is performed on the positive and negative sequence three-phase voltage values ​​respectively to obtain the voltage u of the positive and negative sequence voltage in the two-phase stationary coordinate system sα p 、u sβ p 、u sα n 、u sβ n ;

[0116] Transform the positive and negative sequence voltages in the two-phase stationary coordinate system to the two-phase synchronous rotating coordinate system to obtain u sd p 、u sq p 、u sd n 、u sq n ;

[0117] To u sq p and u sq n The phase of the positive sequence voltage of the 10kV AC feeder line of the power grid can be obtained by using a synchronous rotating coordinate system phase-locked loop (SRFPLL). 1 t and negative sequence voltage phase ω 2 t;

[0118] Figure 3 The control block diagram of the chain type SVG control unit provided by the present invention includes the following steps:

[0119] Output current i to the 10kV AC feeder of the power grid sa 、i sb 、i sc Perform instantaneous positive and negative sequence calculations to obtain the positive and negative sequence three-phase current values ​​i sa p 、i sb p 、i sc p 、i sa n 、i sb n 、i sc n, and then perform Park transformation on the positive and negative sequence three-phase current values ​​respectively to obtain the current i of the positive and negative sequence current in the two-phase synchronous rotating coordinate system sd p 、i sq p 、i sd n 、i sq n ;

[0120] The sum of the DC side voltages of all H-bridge circuits of each phase of the chain SVG is U HdΣA , U HdΣB , U HdΣC Add them together and multiply by 1 / 3 to get the total DC voltage average value U HdΣ . Set the DC voltage reference value The total DC voltage average value U HdΣ Subtract, the difference is input into the voltage loop proportional integral controller, and the output is the d-axis positive sequence current reference value

[0121] Set the d-axis positive sequence current reference value and d-axis positive sequence current i sd p Subtract the difference, and input the current loop proportional integral controller to convert the angular velocity ω, the reactor L and the q-axis positive sequence current i sq p The product of the positive sequence voltage u sd p Add and subtract the output value of the current loop proportional integral controller to obtain the d-axis positive sequence voltage reference value; set the q-axis positive sequence current reference value and the q-axis positive sequence current i sq p Subtract the difference, and input the current loop proportional integral controller to convert the q-axis positive sequence voltage u sq p Subtract the angular velocity ω, the reactor L and the d-axis positive sequence current i sd p The product of , minus the output value of the current loop proportional integral controller, is used to obtain the q-axis positive sequence voltage reference value;

[0122] Set the d-axis negative sequence current reference value and the d-axis negative sequence current i sd n Subtract the difference, and input the current loop proportional integral controller to convert the d-axis negative sequence voltage u sd n Subtract the angular velocity ω, the reactor L and the q-axis negative sequence current i sq nThe product of the current loop proportional integral controller is subtracted to obtain the d-axis negative sequence voltage reference value; the q-axis negative sequence current reference value is set. and the q-axis negative sequence current i sq n Subtract the difference, and input the current loop proportional integral controller to convert the angular velocity ω, the reactor L and the d-axis negative sequence current i sd n The product of the q-axis negative sequence voltage u sq n Add and subtract the output value of the current loop proportional-integral controller to obtain the q-axis negative-sequence voltage reference value;

[0123] The d-axis positive sequence voltage reference value, the q-axis positive sequence voltage reference value, the d-axis negative sequence voltage reference value, and the q-axis negative sequence voltage reference value are respectively subjected to inverse PARK transformation to generate positive and negative sequence modulation voltage u sma p 、u smb p 、u smc p 、u sma n 、u smb n 、u smc n , the positive and negative sequence modulation voltages are added and input into the PWM generator to form the PWM signal g sax , g sbx , g scx , control each H-bridge module of the chained SVG;

[0124] Figure 4 The control block diagram of the three-phase three-port H-bridge inverter circuit control unit provided by the present invention includes the following steps:

[0125] The three-phase voltage u of the AC side of the 380V low-voltage bus ia 、u ib 、u ic Perform Park transformation to obtain the voltage u in the two-phase synchronous rotating coordinate system id 、u iq , and filtered through a low-pass filter. Set the d and q axis voltage reference values ​​to

[0126] d, q axis voltage reference value Respectively with u id 、u iq The filtered values ​​are subtracted, and the difference is input into the voltage loop proportional integral controller. The output value of the voltage loop proportional integral controller is subjected to inverse Park transformation to obtain u ima1 ,u imb1 ,u imc1;

[0127] The three-phase current i on the AC side of the three-phase three-port H-bridge inverter circuit ia 、i ib 、i ic Perform Park transformation to obtain the current i in the two-phase synchronous rotating coordinate system id 、i iq ,i id 、i iq Subtract the values ​​from those after the low-pass filter to get the high-order harmonic current Δi id , Δi iq Δi id , Δi iq Multiply them by the damping coefficient K respectively, and perform inverse Park transformation to obtain the high-order harmonic voltage u ima2 ,u imb2 ,u imc2 ;

[0128] will u ima1 ,u imb1 ,u imc1 With high-order harmonic voltage u ima2 ,u imb2 ,u imc2 Subtract to generate modulation voltage u ima ,u imb ,u imc And input PWM generator to form PWM signal g i1 ~g i6 , to control the three-phase three-port H-bridge inverter circuit.

[0129] The three-port power router topology control method with high-reliability power supply provided by the application embodiment of the present invention is applied to a computer device, wherein the computer device includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the three-port power router topology control method with high-reliability power supply.

[0130] The topology control method of the three-port power router with high reliability power supply provided by the application embodiment of the present invention is applied to an information data processing terminal, and the information data processing terminal is used to implement the three-port power router topology device with high reliability power supply.

[0131] The present invention uses the MATLAB / Simulink simulation experiment platform to build a three-port power router simulation model. The initial phase of the 10kV AC grid is 0 and the frequency is 50Hz; the connected reactor L=20mH; the chain SVG uses 12 H-bridge submodules per phase, each submodule has a switching frequency of 500Hz, a DC voltage set value of 800V, and a DC side capacitor of 3.3mF; the turns ratio of the primary winding to the secondary winding of the three-phase power frequency transformer is 1:1, the nominal power is 50kVA, and the nominal frequency is 50Hz; the switching frequency of the three-phase three-port H-bridge inverter circuit is 10kHz, and the AC side filter inductor L 1 =1mH, filter capacitor C 1 =75μF, the DC side of the three-phase three-port H-bridge inverter circuit passes through the filter capacitor C id =3.3mF connected to 800V DC voltage. The simulation results are as follows Figures 5 to 9 shown.

[0132] Figure 5 The reactive current waveform of the chain SVG provided by the present invention when performing reactive compensation. In the initial stage, the reactive current of the chain SVG maintains a constant command value of 400A. At 0.1s, the reactive current command value is reduced from 400A to 200A. The reactive current of the chain SVG responds quickly to the change of the command value and decreases from 400A to 200A.

[0133] Figure 6 It is the low-voltage AC bus phase voltage waveform provided by the present invention. The amplitude of the low-voltage AC bus port phase voltage is maintained at 311V after 0.4s.

[0134] Figure 7 The present invention provides a phase voltage waveform of a 10kV AC power grid when the voltage drops. At 0.5s, the three-phase voltage drops to 70%;

[0135] Figure 8 The reactive current waveform of the chain SVG provided by the present invention when the voltage of the 10kV AC grid drops, at 0.5s, the three-phase voltage drops to 70%, and the reactive current waveform of the chain SVG maintains the command value of 400A, which verifies the effectiveness of the reactive compensation of the chain SVG;

[0136] Fig. 9 This is the phase voltage waveform of the low-voltage AC bus when the 10kV AC grid voltage drops provided by the present invention. At 0.5s, the three-phase phase voltage drops to 70%, and the phase voltage amplitude of the low-voltage AC bus can be maintained at 311V, which verifies the effectiveness of the voltage control of the three-phase three-port H-bridge inverter circuit and the fault isolation of the chain SVG, and reflects the high reliability of the power supply of the low-voltage AC bus port.

[0137] The present invention provides a three-port power router topology and control method with high-reliability power supply. The topology structure includes a chain SVG, a three-phase three-port H-bridge inverter circuit and an energy storage DC port, forming a fusion between multi-form high and low voltage conversion topologies, making the topology a converter topology with three ports: high voltage AC, low voltage AC and energy storage DC.

[0138] The present invention regulates reactive current through a low-switching-frequency chain SVG, a high-switching-frequency three-phase three-port H-bridge inverter circuit maintains a stable 380V low-voltage AC bus voltage, and a DC port of the three-phase three-port H-bridge inverter circuit is connected to an energy storage device to provide active support for the chain SVG.

[0139] When a high-voltage 10kV AC port fails, the chain SVG can isolate the fault, thereby achieving high-reliability power supply of the 380V low-voltage AC bus, and further connecting sensitive loads.

[0140] The present invention aims to solve the reliability problem of power supply in the prior art, especially to achieve efficient and stable power conversion and distribution in the power system. The existing power supply system faces problems such as unstable power supply, imprecise reactive power control, untimely fault response and isolation. In addition, the traditional system cannot effectively integrate and manage energy from multiple power sources, such as renewable energy generation and energy storage equipment.

[0141] The present invention solves the above problems through the following technical advances:

[0142] 1. Improved power supply reliability: The three-port power router provided by the present invention can quickly isolate the fault when a fault occurs in the power grid and maintain the power supply stability of key loads, thereby improving the reliability of the entire power system.

[0143] 2. Reactive power control and active power support: Through the coordinated work of the chain SVG and the three-phase three-port H-bridge inverter circuit, the present invention can accurately control reactive power and provide necessary active power support for the power grid, thereby optimizing the power quality of the power grid.

[0144] 3. Flexible energy integration: The three-port power router topology design supports the integration of multiple power sources (such as photovoltaic power generation and energy storage equipment), improving the adaptability and utilization of the power system to renewable energy.

[0145] 4. Optimized power flow control: Through advanced control strategies and PWM signal generation, the present invention can achieve precise control of power flow, including energy routing from grid to load, from energy storage to grid / load, and between different power sources.

[0146] 5. Efficient filtering and voltage stabilization: The design of three-phase LC filter and three-phase three-port H-bridge inverter circuit not only provides effective filtering function, but also ensures the voltage stability of the low-voltage AC bus, further improving the overall performance of the power system.

[0147] In summary, the present invention provides a power supply system that is efficient, stable, reliable and easy to integrate multiple electrical energy sources, which significantly improves the power supply quality and operational flexibility of the power system.

[0148] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A three-port power router topology with high reliability power supply, characterized in that: include: Three connected reactors L are used to control the response rate of current changes; A chain-type static VAR generator comprises three cascaded H-bridge converters HJ, each cascaded H-bridge converter HJ is composed of n H-bridge circuits HJ1 to HJn, wherein the value of n is determined comprehensively based on application scenarios, cost and space constraints; Each H-bridge circuit consists of two bridge arms, each of which contains two insulated gate bipolar transistors (IGBTs) and a DC link capacitor CHd; A three-phase isolation transformer, whose primary side is connected to the AC port of the last H-bridge converter HJn of the chain SVG, and whose secondary side is connected to the 380V low-voltage AC bus; A three-phase LC filter includes a filter capacitor C1 and a filter inductor L1, the capacitor C1 is connected in parallel to a 380V low-voltage AC bus, and the inductor L1 is connected in series to a three-phase three-port H-bridge inverter circuit; A three-phase three-port H-bridge inverter circuit, including six IGBT switches (Q1 to Q6), is used to convert the form of electrical energy and maintain the stability of the low-voltage AC bus voltage; An energy storage DC port is connected to the DC side of the three-phase three-port H-bridge inverter circuit and is used to connect a photovoltaic power generation system and a battery energy storage device.

2. The three-port power router topology with high reliability power supply according to claim 1, characterized in that: The chain SVG control unit combines the three-phase voltage and current of the 10kV AC feeder and the DC voltage reference value of each H-bridge circuit of the chain SVG, and uses a phase-locked loop controller, DC voltage control and AC current control to generate a PWM (pulse width modulation) signal to control each IGBT switch tube of the chain SVG; Through the three-phase three-port H-bridge inverter circuit control unit, combined with the three-phase voltage of the 380V low-voltage AC bus and the three-phase current of the three-phase three-port H-bridge inverter circuit, a phase-locked loop controller, AC voltage control and AC current control are used to generate a PWM signal to control the IGBT switch tube of the three-phase three-port H-bridge inverter circuit.

3. The three-port power router topology with high reliability power supply according to claim 2, characterized in that: The chained SVG control unit comprises: The first instantaneous positive and negative sequence calculator is used to calculate the instantaneous positive and negative sequence of the 10kV AC feeder three-phase voltage to obtain the instantaneous three-phase positive and negative sequence voltage of the 10kV AC feeder; A phase-locked loop controller is used to calculate the 10kV AC feeder voltage through phase-locking to obtain the phase of the two-phase synchronous rotating coordinate system; The second instantaneous positive and negative sequence calculator is used to calculate the instantaneous three-phase positive and negative sequence current of the 10kV AC feeder line through the instantaneous positive and negative sequence calculation; A first proportional-integral controller is used to obtain a value obtained by adding the average value of the DC voltage through proportional calculation and integral calculation as a positive-sequence active current reference value in a two-phase synchronous rotating coordinate system; The second proportional integral controller is used for performing proportional calculation and integral calculation on the difference between the positive sequence active current reference value and the actual positive sequence active current value, and the sum of the values ​​obtained is used as the positive sequence active voltage reference value of the chain SVG; A third proportional integral controller is used for performing proportional calculation and integral calculation on the difference between the positive sequence reactive current reference value and the actual value of the positive sequence reactive current, and the sum of the values ​​obtained is used as the chain SVG positive sequence reactive voltage reference value; A first anti-Park controller is used to convert the positive sequence modulation voltage in the two-phase synchronous rotating coordinate system into a three-phase positive sequence modulation voltage reference value in the three-phase stationary coordinate system; A fourth proportional integral controller is used for performing proportional calculation and integral calculation on the difference between the negative sequence active current reference value and the actual negative sequence active current value, and the sum of the values ​​obtained is used as the chain SVG negative sequence active voltage reference value; A fifth proportional integral controller, used for performing proportional calculation and integral calculation on the difference between the negative-sequence reactive current reference value and the actual negative-sequence reactive current value, and adding the summed values ​​as the chain SVG negative-sequence reactive voltage reference value; A second anti-Park controller is used to convert the negative sequence modulation voltage in the two-phase synchronous rotating coordinate system into a three-phase negative sequence modulation voltage reference value in the three-phase stationary coordinate system; The first PWM generator has as input the sum of the chained SVG three-phase positive sequence modulation voltage reference value and the chained SVG three-phase negative sequence modulation voltage reference value, and outputs a PWM driving signal of the chained SVG.

4. The three-port power router topology with high reliability power supply according to claim 2, characterized in that: The three-phase three-port H-bridge inverter circuit control unit comprises: The first Park controller is used to convert the three-phase voltage of the 380V low-voltage AC bus in the three-phase stationary coordinate system into the voltage in the two-phase synchronous rotating coordinate system; A first low-pass filter, used for low-pass filtering the active voltage on the two-phase synchronous rotating coordinate system; a sixth proportional-integral controller, configured to perform proportional calculation and integral calculation on the difference between the active voltage reference value and the actual active voltage value, and to obtain a value as the active voltage reference value of the three-phase three-port H-bridge inverter circuit; A second low-pass filter is used to perform low-pass filtering on the reactive voltage on the two-phase synchronous rotating coordinate system; A seventh proportional-integral controller, used for performing proportional calculation and integral calculation on the difference between the reactive voltage reference value and the actual reactive voltage value, and adding the summed values ​​to obtain the value as the reactive voltage reference value of the three-phase three-port H-bridge inverter circuit; A third anti-Park controller, used for converting the modulation voltage in the two-phase synchronous rotating coordinate system into a three-phase modulation voltage reference value in the three-phase stationary coordinate system; A second Park controller is used to convert the three-phase current of the three-phase three-port H-bridge inverter circuit in a three-phase stationary coordinate system into a current in a two-phase synchronous rotating coordinate system; A third low-pass filter is used to perform low-pass filtering on the active current on the two-phase synchronous rotating coordinate system; a fourth low-pass filter, for low-pass filtering the reactive current on the two-phase synchronous rotating coordinate system; The first damping controller is used to convert the difference between the actual active current and the active current after low-pass filtering into a difference in high-order harmonic voltage; The second damping controller is used to convert the difference between the actual reactive current and the reactive current after low-pass filtering into a difference in high-order harmonic voltage; a fourth anti-Park controller, for converting a high-order harmonic voltage in a two-phase synchronous rotating coordinate system into a three-phase high-order harmonic voltage reference value in a three-phase stationary coordinate system; The second PWM generator has as input the difference between the three-phase modulation voltage reference value and the three-phase higher harmonic voltage reference value, and outputs a PWM drive signal for a three-phase three-port H-bridge inverter circuit.

5. A control method for a chained SVG based on the three-port power router topology of claim 2, characterized in that: The control method of the chained SVG comprises the following steps: (a) Calculate the instantaneous positive and negative sequence of the output voltage of the 10 kV AC feeder of the power grid, perform Clark transformation and transformation in the synchronous rotating coordinate system to obtain the voltage phase; (b) Calculate the instantaneous positive and negative sequence of the output current of the 10 kV AC feeder of the power grid and perform Park transformation to obtain the current in the synchronous rotating coordinate system; (c) Calculate the sum of the DC side voltages of all H-bridge circuits of each phase of the chain SVG and obtain the average value of the total DC voltage to set the current reference value; (d) calculating the d-axis and q-axis positive and negative sequence voltage reference values ​​according to the current reference value and the actual current value; (e) Perform inverse PARK transformation to generate positive and negative sequence modulation voltages, and control each H-bridge module of the chain SVG through a PWM generator. 6 . The control method according to claim 5 , wherein the calculation of the positive and negative sequence voltages further comprises using a synchronous rotating coordinate system phase locked loop to obtain the phases of the positive and negative sequence voltages.

7. The control method according to claim 5, wherein calculating the total DC voltage average value further comprises adding the DC side voltages of the H-bridges of each phase and multiplying the sum by 1 / 3, and comparing the sum with a preset DC voltage reference value to generate a reference value of the d-axis positive sequence current.

8. The control method according to claim 5, wherein the calculation of the d-axis and q-axis voltage reference values ​​further comprises using a current loop proportional-integral controller to adjust the voltage error, and combining the angular velocity and the reactor parameters to obtain the final voltage reference value.

9. The control method according to claim 5, wherein the generation of positive and negative sequence modulation voltages further comprises inverse PARK transforming the positive and negative sequence voltage reference values ​​of the d-axis and q-axis, respectively, and adding the results to the PWM generator to form corresponding PWM signals.

10. A control method for a three-phase three-port H-bridge inverter circuit control unit based on the three-port power router topology of claim 1, characterized in that: The following steps are involved: (a) Perform Park transformation and filtering on the three-phase voltage on the AC side of the 380V low-voltage bus, and set the d-axis and q-axis voltage reference values; (b) calculating the error based on the reference value and the filtered voltage value and inputting it into the voltage loop proportional integral controller; (c) Perform Park transformation on the three-phase current on the AC side, calculate the high-order harmonic current, and multiply it by the damping coefficient; (d) Subtract the voltage value output by the controller from the high-order harmonic voltage to generate a modulation voltage, and control the inverter circuit through the PWM generator.

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