The application relates to a power quality control method applied to a grid where a photovoltaic grid-connected inverter and a chopper multiplexing converter are located

Abstract

This invention belongs to the technical field of photovoltaic new energy grid-connected systems and power electronics, specifically relating to a power quality control method applied to the power grid where photovoltaic grid-connected inverters and chopper multiplexed converters are located, including: extracting the DC component corresponding to the fundamental component in the load current after dq transformation. i a ;control i a The d-axis and q-axis components are multiplied using different sine and cosine operators to obtain the DC component corresponding to the positive-sequence component and the AC component corresponding to the negative-sequence component, respectively. The DC components corresponding to the positive-sequence components of the d-axis and q-axis are then multiplied using different sine and cosine operators to obtain the positive-sequence components of the fundamental frequency component. The positive-sequence components of the d-axis and q-axis fundamental frequency components are then added together. The resulting positive-sequence component is then subjected to PI control and compared with the original fundamental frequency component. i a By performing subtraction calculations, the reactive current command requiring compensation is obtained, thereby achieving three-phase current imbalance control. This invention can efficiently improve the power quality of the circuit where the converter is located.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photovoltaic new energy grid-connected systems and power electronics, and more particularly relates to a power quality control method applied to a grid where a photovoltaic grid-connected inverter and a chopper multiplexing converter are located. BACKGROUND

[0002] With the increase of power load and the access of new energy, the complexity of the power system is improved, and the power quality problem is highlighted, which affects the stable operation of the power system and the safety of the electrical equipment, and the trend of new energy grid-connected system is gradually advancing. Due to the complexity and dispersion of the new energy grid-connected system, the multiplexing converter may have power factor change, voltage imbalance, and harmonic and other power quality problems. The harmonic pollution generated by the multiplexing converter arranged in the photovoltaic grid-connected system becomes an obstacle to the new energy grid-connected system, which not only may damage the electrical equipment and affect the stable operation of the power system, but also may cause damage to the electrical equipment of the user and even threaten personal safety. Therefore, the power quality needs to be improved through control means.

[0003] At present, there are few control research methods for new photovoltaic grid-connected inverter and chopper multiplexing circuits. For the application of such multiplexing converters in photovoltaic grid-connected systems, the harmonic detection and control method usually adopts three-phase current and voltage directly through a low-pass filter to filter out high-frequency harmonic components, which are further used as feedback quantities to control the output of the converter, i.e. to guide the converter to adopt corresponding modulation strategies and control measures. Such control method is simple and clear, but in actual engineering application, the harmonic suppression response speed is slow, and in the case of such multiplexing converters, it cannot give an efficient and stable solution to the problems of current imbalance, low power factor, and existence of many harmonics in the grid. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the application provides a power quality control method applied to a grid where a photovoltaic grid-connected inverter and a chopper multiplexing converter are located, which aims to efficiently improve the power quality in the new photovoltaic grid-connected inverter and chopper multiplexing converter circuit.

[0005] To achieve the above-mentioned purpose, according to one aspect of the application, a power quality control method applied to a grid where a photovoltaic grid-connected inverter and a chopper multiplexing converter are located is provided, which comprises:

[0006] The load current I after dq transformation L After filtering out the alternating component through the low-pass filter LPF, the direct current corresponding to the fundamental component in the load current is obtained i a ; control the direct current i aThe d-axis and q-axis components in the d-axis and q-axis components are subjected to first multiplication operation by different sine and cosine operators, respectively, to obtain direct current corresponding to positive sequence component and alternating current corresponding to negative sequence component, and the alternating current is filtered by a low-pass filter to obtain direct current corresponding to positive sequence component; the direct current corresponding to d-axis and q-axis positive sequence components is subjected to second multiplication operation by different sine and cosine operators to obtain positive sequence components in fundamental components; the positive sequence components in d-axis and q-axis fundamental components are added by an adder, and the added positive sequence components are subjected to PI control, and then the original direct current corresponding to fundamental components i a to obtain reactive current instruction to be compensated i f to realize three-phase current imbalance control.

[0007] Further, the direct current i a The d-axis component adopts a sine and cosine operator , and the q-axis component adopts a sine and cosine operator ; in the formula, N is the number of sampling points in one power frequency cycle of the load current detection device, is the count value of the sampling points in one power frequency cycle, l is the abc three-phase index, wherein , , .

[0008] Further, when the direct current corresponding to d-axis and q-axis positive sequence components is subjected to multiplication operation by different sine and cosine operators, the d-axis component adopts a sine and cosine operator , and the q-axis component adopts a sine and cosine operator ; in the formula, N is the number of sampling points in one power frequency cycle of the load current detection device, is the count value of the sampling points in one power frequency cycle, l is the abc three-phase index, wherein , , .

[0009] Further, it further comprises:

[0010] The detected d-axis voltage of the converter AC side after dq transformation is subjected to subtraction operation with the AC side d-axis voltage instruction, and the operation result is subjected to PI control to realize tracking control of the voltage instruction of the converter AC side, and to obtain the instruction direct current obtained by voltage control; the instruction current is controlled with the d-axis current of the converter AC side after dq transformation and the load current I LSubtracting the AC component from the load current I after the dq transformation, the fundamental component of the load current I is obtained.

[0011] Further, the application further comprises:

[0012] A low-pass filter is used to filter the AC component from the load current I after the dq transformation, and the DC component corresponding to the fundamental component of the load current I is obtained. L i a The DC component is subjected to a dq / abc transformation, and the transformation result is subtracted from the original detected load current I after the dq transformation. i a After that, the grid current ig is subtracted to realize the grid current closed-loop control tracking, and the instruction AC current to be output by the converter is obtained. L The instruction AC current is subjected to a dq transformation and PR control, and the modulation voltage acting on the switch tube of the converter is obtained to realize the harmonic closed-loop control.

[0013] According to another aspect of the application, a photovoltaic grid-connected inverter and chopping multiplexing converter is provided, comprising a controller configured to perform the power quality control method applied to the grid where the photovoltaic grid-connected inverter and chopping multiplexing converter is located.

[0014] According to another aspect of the application, an electronic device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to realize the steps of the method.

[0015] According to another aspect of the application, a computer readable storage medium is provided, comprising a stored computer program, wherein the computer program is executed by a processor to control the device where the storage medium is located to perform the steps of the method.

[0016] According to another aspect of the application, a computer program product is provided, comprising a computer program or instructions, which are executed by a processor to realize the steps of the method.

[0017] Overall, compared with the prior art, the technical scheme provided by the application has the following beneficial effects:

[0018] ​1. The application proposes a power quality control method applied to the grid where the photovoltaic grid-connected inverter and chopper multiplexing converter are located. The designed method based on time-domain current detection negative sequence current control grid current imbalance is compared with the traditional control method. Since this method uses the orthogonal characteristics of trigonometric function transformation in principle: the positive sequence, negative sequence and zero sequence are orthogonal in the current decomposition process, the sampled three-phase current is decomposed into positive sequence, negative sequence and zero sequence in the operation, therefore it can be used for the detection and control of the fundamental unbalanced component of the three-phase four-wire system and single-phase system current, and efficiently improves the power quality in the new photovoltaic grid-connected inverter and chopper multiplexing converter circuit.

[0019] 2. The application further proposes power and voltage double closed-loop control. The power and voltage control used adopts a double closed-loop control structure, the inner loop controls the stable output of the current, and the outer loop controls the stable output of the voltage; by designing reasonable closed-loop control parameters, the power quality of the output current and voltage of the grid-connected inverter is improved, and the load current under the condition of multiplexing chopper circuit can be controlled.

[0020] 3. The application further proposes harmonic closed-loop control. The designed closed-loop control harmonic processing mode is compared with the traditional open-loop harmonic control mode: the traditional detection load harmonic control may be distorted due to circuit resonance, and the improved detection grid current closed-loop control will eventually feedback the harmonics in the grid to the control system for closed-loop regulation. The application combines the two control modes, and the actual harmonic filtering effect is more stable. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the control object of the method of the application provided by the embodiment of the application, that is, the new photovoltaic grid-connected inverter and chopper multiplexing converter circuit topology diagram;

[0022] Figure 2 is the simplified schematic diagram of the equivalent model of the new photovoltaic grid-connected inverter and chopper multiplexing converter provided by the embodiment of the application;

[0023] Figure 3 is the time-domain current compensation control schematic diagram of the grid current imbalance provided by the embodiment of the application;

[0024] Figure 4 is the power and voltage double closed-loop control logic schematic diagram provided by the embodiment of the application;

[0025] Figure 5 is the harmonic closed-loop detection and control schematic diagram provided by the embodiment of the application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0027] Embodiment one

[0028] An electric energy quality control method applied to a grid where a photovoltaic grid-connected inverter and a chopping multiplexing converter are located, comprising:

[0029] The load current I after dq transformation L After filtering out the alternating component through a low-pass filter LPF, the direct current corresponding to the fundamental component in the load current is obtained i a The d-axis and q-axis components in the control direct current i a The d-axis and q-axis components in the control direct current i a The reactive current instruction to be compensated is obtained by subtracting calculation i f .

[0030] Figure 1 As shown in the figure, the control object of the present application is a new grid-connected inverter and chopping multiplexing converter circuit topology, 1 part is a high-frequency zigzag transformer, 2 part is a user-side photovoltaic cell, 3 part is a three-phase grid-connected inverter and chopping multiplexing converter and a controller. AC represents the grid, wherein the user-side photovoltaic cell transmits electric energy to the direct current side energy storage end through chopping conversion, and the grid side and the direct current side energy storage end realize the exchange of electric energy by using the inverter and rectifier functions of the converter (the grid transmits to the direct current side as rectification, and the direct current side transmits to the grid as inversion).

[0031] First, the equivalent model of the photovoltaic grid-connected converter is simplified, as shown in Figure 2 It is a multi-input multi-output coupled model, and the brief equivalent process of this model is as follows:

[0032] According to the grid-connected circuit topology of the converter, the voltage and current equations of the photovoltaic grid-connected converter with respect to the converter and the grid can be written as shown in Equation Group 1:

[0033] (1)

[0034] In Equation Group 1, is the voltage of the grid side, and o represents the neutral point of the grid side, is the current flowing from the converter side to the reference direction of the grid side, is the equivalent electrical impedance between the converter and the grid via the zigzag transformer and the line LCL filter, is the relative voltage of the three-phase converter output end and the grid line neutral point.

[0035] At this time, the d-q transformation of the model is needed to facilitate subsequent double closed-loop, harmonic and unbalanced control, so that the equivalent model parameters of the converter can be obtained, as shown in Equation Group 2:

[0036] (2)

[0037] In Equation Group 2, is the voltage of the grid side after d-q transformation, is the voltage of the AC measurement of the converter after d-q transformation, is the current in the line of the AC measurement of the converter, is the equivalent impedance, that is, Figure 1 , is the frequency.

[0038] Therefore, the equivalent model of the photovoltaic grid-connected converter in the d-q coordinate system can be obtained as shown in Equation Group 3: Figure 1 In order to eliminate the coupling of the d-q axis system, a decoupling control part wL is introduced.

[0039] Since the model after the equivalent simplification is still a multiple-input multiple-output model, the process is complicated and cumbersome in control design, therefore, the converter model is further simplified to a single-input single-output model structure, for the input , a feedforward decoupling can be adopted to compensate so as to make the input equivalent to , let​​​​​​​​​​​​​Figure 3 Model in The whole is , so as to equivalent the converter to a single-input single-output model, and meet the following formula 3 relationship:

[0040] (3)

[0041] The object of the application and control is a new type of photovoltaic grid-connected inverter and chopper multiplexing converter. Due to the demand and supply relationship between users and enterprises in the engineering implementation process, the control strategy of adding the original converter DC chopper function on the basis of the inverter control function is adopted, so in the application the control object of the converter is simplified to a photovoltaic grid-connected inverter model, which includes Q1-Q6 total 6 IGBT, D1-D6 total 6 diodes. The control method described in the application is designed on the basis of further equivalent of the photovoltaic grid-connected inverter model, therefore the application proposes the process of simplifying and equivalent model of the circuit topology to facilitate understanding.

[0042] The power quality control method applied to the new type of photovoltaic grid-connected inverter and chopper multiplexing converter in the grid is proposed in the embodiment. After the load current after dq transformation is filtered by the low-pass filter LPF, only the fundamental component converted into DC is contained in ia, the d-axis and q-axis components are subjected to a series of multiplication operations by different operators (sin and cos), and the corresponding positive and negative sequence components can be separated, wherein the positive sequence component is converted into DC, and the negative sequence component is converted into AC. After passing through the low-pass filter again, the positive sequence component converted into DC by multiplication operation is obtained, and the positive sequence component is restored into AC by a series of multiplication operations by the operator (sin and cos) again. Finally, compared with the original fundamental component ia, the reactive current instruction if required for compensation can be obtained, and three-phase current imbalance control is realized.

[0043] As Figure 4 The flow chart of three-phase imbalance detection and control is shown in the figure, is the abc three-phase index: , , ; is the number of sampling points in a power frequency cycle of the current detection device, is the count value of the sampling points in a power frequency cycle, and SPLL is a phase-locked loop, which is a sine and cosine operator required for converting the positive sequence current into DC and the negative sequence current into AC. The current detection device will perform FFT conversion, and the input signal is a series of Fourier series sum formula 4:

[0044] (4)

[0045] After harmonic filtering, this series only contains Item, as preferred, using and Operation, and then through the low-pass filter can get the current negative sequence component, the current negative sequence component at this time is the after the change of the direct current, respectively through and The multiplier can get the current negative sequence component, combined with PI controller for closed-loop control adjustment to make the control system stable, so as to realize the imbalance detection and control.

[0046] Overall, the three-phase current imbalance control part includes synchronous phase lock loop, adder, PI regulator and multiplier. This part is mainly for harmonic control has been filtered out after the high harmonic, in the fundamental frequency band power grid due to load current and the system itself exists in the influence of power electronic and new energy equipment, power grid current will exist negative sequence component, resulting in the current imbalance in photovoltaic grid-connected system; using multiplication and current operation, extraction of the negative sequence component, and design of PI closed loop control, so as to solve the problem of current imbalance of grid side, reduce the interference of nonlinear load to the system power quality problem.

[0047] As preferred, the control method further comprises:

[0048] The detected d-axis voltage of the converter AC side after dq transformation is subtracted from the AC side d-axis voltage command, and the operation result is subjected to PI control to realize the tracking control of the voltage command of the converter AC side, and the command DC current obtained through voltage control is obtained; the control command current is subtracted from the d-axis current of the converter AC side after dq transformation and the load current I L The subtraction operation is performed to obtain the command DC current to be output by the converter; the command current is subjected to G(s) control to obtain the modulation voltage acting on the switch tube of the converter to realize power and voltage double closed loop control.

[0049] In this embodiment, voltage and current double closed loop control is adopted for the converter to improve the response speed and stability of the system, and the double closed loop control structure diagram is as shown in Figure 5 .

[0050] The outer ring adopts voltage closed loop control, and the feedback voltage is the direct axis component of the three-phase voltage measured by the converter AC after d-q transformation. Since the converter AC is connected to the grid, in order to cooperate with the grid, the voltage feedback outer ring is introduced, and after the reference value of the voltage is set, the control system can make the voltage output of the converter stable after PI parameter adjustment.

[0051] The inner ring adopts current closed loop control, is the current of the inverter output after d-q transformation, and the current of the load end The specified current of the converter is controlled by a double closed loop, which includes the grid current and the load current. The current after operation is passed through the G(s) link again, so that the voltage target value is converted into the current target value, and then the current target value is converted into the equivalent voltage value acting on the inverter The current value of the final converter output port can be calculated by formula (3).

[0052] In general, the voltage and power control involves: given active and reactive, d-axis and q-axis current parts of the grid side after abc / dq transformation, WL decoupling part, PI regulator, adder and subtractor, PPL phase-locked loop, and abc three-phase voltage and current oscilloscope. This part mainly controls the active and reactive components in the three-phase current, and uses the equivalent model of the grid-connected inverter to adjust the duty cycle of the converter switch tube in a decoupling manner, so as to change the output voltage and current of the converter ac measurement, and compensate the harmonic and reactive current of the grid line.

[0053] As a preferred embodiment, the control method further comprises:

[0054] The low-pass filter is used to filter out the ac component of the load current I after dq transformation, and the dc component corresponding to the fundamental component of the load current is obtained L i a The dq / abc transformation is performed on the dc i a , and the transformed result is subtracted from the original detected load current I L after dq transformation, and then subtracted from the feedback current ig in the grid to realize grid current closed-loop control tracking, so as to obtain the instruction ac current to be output by the converter; dq transformation is performed on the instruction ac current, and PR control is performed to obtain the modulation voltage acting on the converter switch tube, so as to realize harmonic closed-loop control.

[0055] That is, the current at the ac side load is detected, the d-axis component and the q-axis component are obtained after abc / dq transformation, the load ac component is filtered out by the low-pass filter, only the fundamental component of the load current converted into dc by dq is allowed to pass, and the harmonic current to be compensated is obtained by comparing with the original detected load current. The periodic tracking of the harmonic is realized by the PR regulator to obtain the adjustment signal V d , and the action converter model can obtain i d . Since the purpose of this control method is to compensate the harmonic current of the grid side, the current of the grid side is introduced for closed-loop control.

[0056] ​As ​ Figure 2 shows a flow chart of the harmonic detection and control, is the load-side detected current after d-q transformation, is the d-axis component of the grid-side current after d-q transformation, wherein the non-fundamental component becomes an alternating component and the fundamental component becomes a direct component after d-q transformation, and only the alternating component is filtered out by adding a low-pass filter (LPF) to the current after d-q transformation, and the remaining direct component is used as the target quantity for regulation and control; the traditional harmonic compensation control adopts open-loop control, which detects the load current and then filters and controls the detected load current, and this method requires high detection accuracy, and the present application adds closed-loop control of the grid side, detects the harmonic component in the grid current on the basis of the original detection of the load current , and feeds it back to the harmonic current control, and uses PR proportional resonance control which can track the periodic alternating control quantity well to ensure tracking of the alternating input quantity, thereby achieving efficient management of harmonics in the grid-connected system.

[0057] In summary, the harmonic control part involves the d-axis and q-axis current parts after abc / dq transformation of the load side, a low-pass filter, an adder and a subtractor, the d-axis and q-axis current parts after abc / dq transformation of the grid side, and a PI regulator. This part mainly detects the harmonic component in the nonlinear load, and combines open-loop and closed-loop control to enable the photovoltaic grid-connected inverter to output the corresponding harmonic current, thereby reducing the harmonic component of the grid-side current and reducing the impact of the power electronic device (i.e. multiplexing converter) on the power quality of the grid.

[0058] Embodiment Two

[0059] A photovoltaic grid-connected inverter and chopping multiplexing converter, comprising a controller configured to execute the power quality control method applied to the grid where the photovoltaic grid-connected inverter and chopping multiplexing converter are located.

[0060] The related technical solutions are the same as those in Embodiment One, and will not be described here again.

[0061] Embodiment Three

[0062] The present application also relates to an electronic device comprising a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above method.

[0063] The electronic device can be a desktop computer, a notebook computer, a palm computer, a cloud server, and the like. The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, and the like. The memory can be used to store computer programs and / or modules, and the processor can execute or run the computer programs and / or modules stored in the memory and call data stored in the memory, to implement various functions of the electronic device.

[0064] The related technical solutions are the same as above, and will not be repeated here.

[0065] Embodiment Four

[0066] The present application also relates to a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the above method.

[0067] Specifically, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one disk storage device, a flash memory device, or other volatile solid-state memory devices.

[0068] The related technical solutions are the same as above, and will not be repeated here.

[0069] Embodiment Five

[0070] The present application embodiment provides a computer program product or a computer program, which includes computer instructions stored in a computer readable storage medium. The processor of the computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions, so that the computer device executes the steps of the above-mentioned embodiment method of the present application.

[0071] The related technical solutions are the same as above, and will not be repeated here.

[0072] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A power quality control method applied to a grid where a photovoltaic grid-connected inverter and a chopper multiplexing converter are located, characterized in that, The circuit topology of the grid where the photovoltaic grid-connected inverter and chopper multiplexing converter is applied includes: a high-frequency zigzag transformer, a user-side photovoltaic cell, a three-phase grid-connected inverter and chopper multiplexing converter and a controller, and a grid AC; wherein the high-frequency zigzag transformer includes a first winding and a second winding, the grid AC is arranged between the first winding and the second winding, the second winding is connected to the AC side of the inverter and chopper multiplexing converter, and the DC side of the inverter and chopper multiplexing converter is externally connected to a DC bus end energy storage; one side of the user-side photovoltaic cell is connected to one end of the first winding away from the grid AC, and the other side is connected to the negative end of the energy storage; The control method comprises: Control the load current I after dq transformation L After filtering out the alternating component through the low-pass filter LPF, the direct current corresponding to the fundamental component in the load current is obtained i a ; Control the d-axis and q-axis components in the direct current i a The d-axis and q-axis components in the direct current are subjected to first multiplication operation through different sine and cosine operators, respectively, to obtain the direct current corresponding to the positive sequence component and the alternating current corresponding to the negative sequence component, respectively, and the alternating current is filtered out through a low-pass filter to obtain the direct current corresponding to the positive sequence component; the direct currents corresponding to the d-axis and q-axis positive sequence components are subjected to second multiplication operation through different sine and cosine operators, respectively, to obtain the positive sequence component in the fundamental component; the positive sequence components in the d-axis and q-axis fundamental components are added through an adder, and the added positive sequence component is subjected to PI control, and then subtracted from the direct current corresponding to the original fundamental component i a to obtain the reactive current instruction that needs to be compensated i f to realize three-phase current imbalance control.

2. The power quality control method of claim 1, wherein, Controlling direct current i a When the d-axis and q-axis components in the equation are multiplied by different sine and cosine operators, the sine and cosine operator used for the d-axis component is and the sine and cosine operator used for the q-axis component is ; where N is the number of samples taken by the load current detection device in one power frequency cycle, is the count of the number of samples taken in one power frequency cycle, l is an index for the three phases of abc, where , , .

3. The power quality control method of claim 1, wherein, When the direct current corresponding to the d-axis and q-axis positive sequence components is subjected to the second multiplication operation by different sine and cosine operators, the sine and cosine operator adopted for the d-axis component is , and the sine and cosine operator adopted for the q-axis component is ; in the formula, N is the number of sampling points in one power frequency cycle of the load current detection device, is the count value of the sampling points in one power frequency cycle, l is the abc three-phase index, wherein , , .

4. The power quality control method of claim 1, wherein, Further comprising: The detected dq-transformed converter AC side d-axis voltage is subtracted from the AC side d-axis voltage instruction, and the result is subjected to PI control to achieve tracking control of the voltage instruction by the converter AC side, obtaining an instruction DC current obtained through voltage control; the control instruction current is subtracted from the dq-transformed converter AC side d-axis current and the dq-transformed load current I L The result is subtracted to obtain an instruction DC current to be output by the converter; the instruction DC current is subjected to G(s) control to obtain a modulation voltage acting on the converter switch tube, so as to achieve double-loop control of power and voltage.

5. The power quality control method according to any one of claims 1 to 4, characterized in that, Further comprising: A low-pass filter is used to filter out the load current I after dq transformation. L The AC component in the load current is used to obtain the DC component corresponding to the fundamental component of the load current. i a ; for this DC i a Perform a dq / abc transformation, and compare the transformation result with the original detected load current I after the dq transformation. L A subtraction operation is performed, followed by a subtraction operation with the current ig fed back from the power grid, to achieve closed-loop control tracking of the power grid current and obtain the command AC current to be output by the converter. The command AC current is then transformed by abc / dq and controlled by PR to obtain the modulation voltage that acts on the switching diode of the converter, so as to achieve harmonic closed-loop control.

6. A photovoltaic grid-connected inversion and chopper multiplexing current converter comprising a controller, characterized in that, The controller is used to execute the power quality control method applied to the grid where the photovoltaic grid-connected inverter and chopper multiplexing converter is located according to any one of claims 1 to 5. 7.An electronic device comprising a memory and a processor, the memory storing a computer program, wherein, The processor executes the computer program to realize the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium includes a stored computer program, wherein when the computer program is run by the processor, the device where the storage medium is located executes the steps of the method according to any one of claims 1 to 5.

9. A computer program product comprising computer programs or instructions, characterized in that, The computer program or instructions are executed by the processor to realize the steps of the method according to any one of claims 1 to 5.

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