Control method and system for accessing anti-resonance energy storage converter to grid-connected system, terminal and medium

Abstract

The invention relates to the technical field of power grids, in particular to a control method and system for an anti-resonance energy storage converter to be connected to a grid-connected system, a terminal and a medium. FFT Fourier transform is carried out on obtained current voltage and current of a grid-connected point, a complex time domain signal is decomposed into superposition of a plurality of simple sine and cosine functions, and the voltage and current of the grid-connected point are obtained; in a spectrogram, the frequency components and characteristics of the signal, including the amplitude and phase information of each frequency component, including harmonic parameters and characteristic sub-harmonics, can be clearly obtained. In the step S2, negation can be carried out on harmonic waves appearing in the grid-connected system through characteristic subharmonic waves, and deduction effect reduction is carried out on the harmonic waves. In the step S4, when the harmonic parameter still exceeds the preset standard value after the step S2 is carried out, it shows that harmonic oscillation causes a resonance phenomenon, and at the moment, the system impedance is changed by adjusting the virtual impedance of the energy storage converter, so that the harmonic oscillation can be weakened or even eliminated to a great extent.

Description

Technical Field

[0001] The present invention relates to the technical field of power grids, and in particular to a control method, system, terminal and medium for connecting an anti-resonance energy storage converter to a grid-connected system. Background Art

[0002] With the vigorous development of new energy, the large-scale access of photovoltaic, wind power and energy storage has brought great impact and challenges to the power grid. On the one hand, the random volatility of new energy power generation will cause fluctuations in the voltage and frequency of the power grid. For example, changes in wind speed and light intensity will affect the output power of wind farms and photovoltaic power stations, thereby causing voltage fluctuations and flicker. When the proportion of new energy in the power grid increases, the stability of the power grid frequency will also be affected. On the other hand, the connection of new energy to the grid may cause harmonic problems. Power electronic devices, compensation capacitors, etc. in photovoltaic power stations and wind farms may cause harmonic pollution and affect the power quality of the power grid.

[0003] The energy storage converter is a device used to control the charging and discharging process of the battery and realize AC-DC conversion. It is mainly composed of a DC / AC bidirectional converter and a control unit, etc. It can connect the energy storage battery system and the power grid, and accurately and quickly adjust the voltage, frequency, and power between the power grid and the energy storage system. By receiving the background control command, the energy storage converter can control the converter to charge or discharge the battery according to the sign and size of the power command, so as to adjust the active power and reactive power of the power grid. The working principle of the energy storage converter is based on power electronics technology and energy storage technology. By controlling the conduction and disconnection of the switch tube, the storage and release of electric energy are realized. It can convert DC into AC, or convert AC into DC, and is an efficient electric energy storage and regulation device. In the new energy power generation system, the energy storage converter can store excess electric energy and release it when needed.

[0004] With the continuous access to new energy sources, not only will the power quality of the power grid become worse, but the difficulty of connecting new energy sources to the grid will also become more and more difficult. The probability of grid resonance and frequency imbalance will gradually increase; the risk of equipment failure, malfunction, and even explosion will gradually increase. Summary of the invention

[0005] In order to solve the technical problems that grid harmonics appear in the grid-connected system after the access of new energy to the grid, resulting in high difficulty in grid connection, poor power quality and low system safety, the present invention proposes a control method, system, terminal and medium for connecting an anti-resonance energy storage inverter to the grid-connected system.

[0006] To achieve the above objectives, in the first aspect, the present application proposes a control method for connecting an anti-resonance energy storage converter to a grid-connected system, and the technical solution adopted is: A control method for connecting an anti-resonance energy storage converter to a grid-connected system comprises the following steps: S1. Sampling the voltage and current of the grid connection point to obtain the current voltage and current of the grid connection point; performing FFT Fourier transform on the current voltage and current of the grid connection point, calculating the harmonic parameters based on the results of the FFT Fourier transform, and judging whether the harmonic parameters exceed the preset standard values; the grid connection point is the connection point between the energy storage system and the power grid, the energy storage system includes an energy storage converter, a new energy power generation device and a load, and the energy storage converter, the new energy power generation device and the load are connected in parallel; S2. When the harmonic parameter does not exceed the preset standard value, return to step S1; when the harmonic parameter exceeds the preset standard value, extract the characteristic subharmonic based on the result of FFT Fourier transform and invert it to obtain the opposite wave, modulate the opposite wave by carrier wave and perform PWM pulse width modulation to inject it into the energy storage system; S3, sampling the voltage and current of the grid connection point, obtaining the current voltage and current of the grid connection point, performing FFT Fourier transform on the obtained current voltage and current of the grid connection point, calculating the harmonic parameters based on the results of the FFT Fourier transform, and judging whether the harmonic parameters exceed the preset standard values; S4. When the harmonic parameter does not exceed the preset standard value, return to step S1; when the harmonic parameter exceeds the preset standard value, detect the system impedance value at the resonant frequency, match the system impedance value at the resonant frequency with the grid-connected virtual impedance, obtain the power required to be output by the energy storage inverter, and adjust the energy storage inverter based on the power required to be output by the energy storage inverter.

[0007] Perform FFT Fourier transform on the current voltage and current of the grid-connected point, decompose the complex time domain signal into the superposition of multiple simple sine and cosine functions, and obtain the spectrum distribution of the signal. In the spectrum diagram, the frequency components and characteristics of the signal can be clearly obtained, including the amplitude and phase information of each frequency component, including harmonic parameters and characteristic subharmonics. In step S2, the harmonics appearing in the grid-connected system can be offset by negating the characteristic subharmonics. In step S4, if the harmonic parameters still exceed the preset standard value after step S2, it means that harmonic oscillation has occurred and caused resonance. At this time, by adjusting the virtual impedance of the energy storage inverter to change the system impedance, the harmonic oscillation can be greatly weakened or even eliminated.

[0008] Therefore, when photovoltaic, wind power, and energy storage are connected to the grid on a large scale, through the control method of the present invention, on the one hand, the harmonics appearing in the grid-connected system can be offset and reduced through this control method, thereby greatly optimizing the grid environment, optimizing the power quality of the grid, reducing the difficulty of grid connection, and improving the safety of the system; on the other hand, when the harmonics cannot be offset, it means that harmonic oscillation has occurred and caused resonance. At this time, the virtual impedance of the grid is matched based on the system impedance value at the resonance frequency, and the virtual impedance of the energy storage converter is adjusted to change the system impedance, which greatly weakens or eliminates harmonic oscillations and weakens or eliminates the impact of resonance. Through the above two control strategies, the present invention can effectively optimize the power quality of the grid, reduce the difficulty of grid connection, improve system safety, and keep the load in normal operation without being affected by harmonics.

[0009] As a preferred implementation of a control method for connecting an anti-resonance energy storage converter to a grid-connected system, detecting the system impedance value at the resonant frequency in step S5, and matching the grid-connected virtual impedance based on the system impedance value at the resonant frequency includes the following steps: Measure the effective value of the voltage and current at the grid connection point, and calculate the reactive power of the system based on the effective value of the voltage and current at the grid connection point ,

[0010] In the formula, Point voltage effective value, is the effective value of the grid-connected point current, is the grid-connected point power factor, Reactive power of the system; Calculate the system reactive power at the resonant frequency , , , In the formula, is the system reactive power at the resonant frequency, is the required harmonic order, and is the system impedance value at the resonant frequency; System reactive power based on resonant frequency and the reactive power of the system The difference between the values ​​of and calculates the system reactive power required to be compensated at the resonant frequency. , that is, the power required to be output by the energy storage converter: .

[0011] As a preferred implementation of a control method for connecting an anti-resonance energy storage converter to a grid-connected system, the harmonic parameters in step S2 include harmonic content and harmonic distortion rate.

[0012] Harmonic content and harmonic distortion rate are important parameters that describe the degree of waveform distortion. Too high harmonic content will have an adverse effect on the stability and performance of the power system, such as causing voltage fluctuations, increased current, equipment damage and other problems. At the same time, harmonics may also cause resonance, further exacerbating the stability problems of the power system. The higher the harmonic distortion rate, the greater the degree of waveform distortion. This will have an adverse effect on the stability and performance of the power system, such as causing voltage waveform distortion, current waveform distortion and other problems. At the same time, high harmonic distortion rate may also cause equipment failures, reduce system efficiency and other problems.

[0013] As a preferred implementation of a control method for connecting an anti-resonance energy storage converter to a grid-connected system, in step S1, the voltage and current of the grid-connected point are sampled, wherein the number of sampling points is 200-300.

[0014] More sampling points can more accurately reflect the changes in the signal in the time domain, thereby obtaining more accurate results in the frequency domain and improving the accuracy of the FFT Fourier transform.

[0015] In the second aspect, the present application proposes a control system for connecting an anti-resonance energy storage converter to a grid-connected system, and the technical solution adopted is: A control system for connecting an anti-resonance energy storage converter to a grid-connected system, comprising a sampling module, an FFT Fourier transform module, a judgment module, a harmonic cancellation module and an adjustment module, wherein: The sampling module is configured to sample the voltage and current of the grid connection point to obtain the current voltage and current of the grid connection point; The FFT Fourier transform module is configured to perform FFT Fourier transform on the acquired current voltage and current of the grid connection point; The judging module is configured to calculate harmonic parameters based on the result of FFT Fourier transform, and judge whether the harmonic parameters exceed the preset standard value; The harmonic cancellation module is configured to extract characteristic subharmonics based on the results of FFT Fourier transform and invert them to obtain opposite waves when the harmonic parameters exceed the preset standard values, and then perform carrier modulation and PWM pulse width modulation on the opposite waves to inject them into the energy storage system; The adjustment module is configured to detect the system impedance value at the resonant frequency when the harmonic parameter exceeds the preset standard value, match the grid-connected virtual impedance based on the system impedance value at the resonant frequency, and adjust the output parameters of the energy storage converter based on the grid-connected virtual impedance.

[0016] As a preferred implementation of a control system for connecting an anti-resonance energy storage converter to a grid-connected system, the harmonic parameters include harmonic content and harmonic distortion rate.

[0017] As a preferred implementation of a control system for connecting an anti-resonance energy storage converter to a grid-connected system, the sampling module has 200-300 sampling points.

[0018] In the third aspect, the present application proposes a terminal, and the technical solution adopted is: A terminal comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the control method for connecting an anti-resonance energy storage converter to a grid-connected system as described above are implemented.

[0019] In a fourth aspect, the present application proposes a storage medium, and the technical solution adopted is: A storage medium stores a computer program, which, when executed by a processor, implements the steps of a control method for connecting an anti-resonance energy storage converter to a grid-connected system as described above.

[0020] The beneficial effects of the present invention include: Therefore, when photovoltaic, wind power, and energy storage are connected to the grid on a large scale, through the control method of the present invention, on the one hand, the harmonics appearing in the grid-connected system can be offset and reduced through this control method, thereby greatly optimizing the grid environment, optimizing the power quality of the grid, reducing the difficulty of grid connection, and improving the safety of the system; on the other hand, when the harmonics cannot be offset, it means that harmonic oscillation has occurred and caused resonance. At this time, the virtual impedance of the grid is matched based on the system impedance value at the resonance frequency, and the virtual impedance of the energy storage converter is adjusted to change the system impedance, which greatly weakens or eliminates harmonic oscillations and weakens or eliminates the impact of resonance. Through the above two control strategies, the present invention can effectively optimize the power quality of the grid, reduce the difficulty of grid connection, improve system safety, and keep the load in normal operation without being affected by harmonics. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 It is a flow chart of a control method for connecting an anti-resonance energy storage converter to a grid-connected system in a specific implementation manner of the present invention.

[0023] Figure 2 It is a wiring diagram of the energy storage converter connected to the grid-connected system in a specific implementation manner of the present invention; Figure 3 It is an equivalent circuit diagram of the energy storage converter connected to the grid-connected system in a specific implementation manner of the present invention; Figure 4 A circuit diagram of a parallel resonance equivalent model in a specific implementation manner of the present invention; Figure 5 It is a structural schematic diagram of a control system in which an anti-resonance energy storage converter is connected to a grid-connected system in a specific implementation manner of the present invention; Figure 3 In is the equivalent grid system impedance, is the equivalent grid system reactance, is the equivalent load capacitive reactance, is the equivalent load reactance, is the equivalent load resistance; Figure 4 middle is the fundamental inductive reactance of the equivalent model, and R is the equivalent resistance of the equivalent model. DETAILED DESCRIPTION

[0024] Harmonics refer to the electrical quantities in the current whose frequencies are integer multiples of the fundamental wave. They generally refer to the electrical quantities generated by the remaining currents that are greater than the fundamental frequency after the Fourier series decomposition of periodic non-sinusoidal electrical quantities.

[0025] When photovoltaic power, wind power and energy storage are connected to the grid on a large scale, it will bring great impact and challenges to the grid. On the one hand, the random volatility of renewable energy generation will cause fluctuations in grid voltage and frequency. For example, changes in wind speed and light intensity will affect the output power of wind farms and photovoltaic power stations, thereby causing voltage fluctuations and flicker. When the proportion of renewable energy in the grid increases, the stability of grid frequency will also be affected. On the other hand, the connection of renewable energy to the grid may cause harmonic problems. Power electronic devices, compensation capacitors, etc. in photovoltaic power stations and wind farms may cause harmonic pollution and affect the power quality of the grid. Not only will the power quality environment of the grid become increasingly worse, but the difficulty of connecting renewable energy to the grid will also become increasingly difficult. The probability of grid resonance and frequency imbalance will gradually increase; the risk of equipment failure, malfunction, and even explosion will gradually increase.

[0026] Therefore, how to reduce or eliminate the impact of harmonics in energy storage grid-connected systems needs to be solved urgently.

[0027] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in this specific embodiment. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] Reference Figure 1This embodiment provides a control method for connecting an anti-resonance energy storage converter to a grid-connected system, comprising the following steps: S1. Sampling the voltage and current of the grid connection point to obtain the current voltage and current of the grid connection point; performing FFT Fourier transform on the current voltage and current of the grid connection point, calculating the harmonic parameters based on the results of the FFT Fourier transform, and judging whether the harmonic parameters exceed the preset standard values; the grid connection point is the connection point between the energy storage system and the power grid, the energy storage system includes an energy storage converter, a new energy power generation device and a load, and the energy storage converter, the new energy power generation device and the load are connected in parallel; S2. When the harmonic parameter does not exceed the preset standard value, return to step S1; when the harmonic parameter exceeds the preset standard value, extract the characteristic subharmonic based on the result of FFT Fourier transform and invert it to obtain the opposite wave, modulate the opposite wave by carrier wave and perform PWM pulse width modulation to inject it into the energy storage system; S3, sampling the voltage and current of the grid connection point, obtaining the current voltage and current of the grid connection point, performing FFT Fourier transform on the obtained current voltage and current of the grid connection point, calculating the harmonic parameters based on the results of the FFT Fourier transform, and judging whether the harmonic parameters exceed the preset standard values; S4. When the harmonic parameter does not exceed the preset standard value, return to step S1; when the harmonic parameter exceeds the preset standard value, detect the system impedance value at the resonant frequency, match the system impedance value at the resonant frequency with the grid-connected virtual impedance, obtain the power required to be output by the energy storage inverter, and adjust the energy storage inverter based on the power required to be output by the energy storage inverter.

[0029] This embodiment performs FFT Fourier transform on the current voltage and current of the grid-connected point, decomposes the complex time domain signal into the superposition of multiple simple sine and cosine functions, and obtains the spectrum distribution of the signal. In the spectrum diagram, the frequency components and characteristics of the signal can be clearly obtained, including the amplitude and phase information of each frequency component, including harmonic parameters and characteristic subharmonics. In step S2, the harmonics appearing in the grid-connected system can be negated by the characteristic subharmonics to reduce the harmonics. In step S4, after performing step S2, if the harmonic parameters still exceed the preset standard value, it means that harmonic oscillation has occurred and caused a resonance phenomenon. At this time, by adjusting the virtual impedance of the energy storage inverter to change the system impedance, the harmonic oscillation can be greatly weakened or even eliminated.

[0030] Therefore, when photovoltaic, wind power, and energy storage are connected to the grid on a large scale, through the control method of this embodiment, on the one hand, the harmonics appearing in the grid-connected system can be offset and reduced through this control method, thereby greatly optimizing the grid environment, optimizing the grid power quality, reducing the difficulty of grid connection, and improving system safety; on the other hand, when the harmonics cannot be offset, it means that harmonic oscillation has occurred and caused resonance. At this time, the grid-connected virtual impedance is matched based on the system impedance value at the resonant frequency, and the virtual impedance of the energy storage converter is adjusted to change the system impedance, thereby greatly reducing or eliminating harmonic oscillations and the impact of resonance.

[0031] Through the above two control strategies, this embodiment can effectively optimize the power quality of the power grid, reduce the difficulty of grid connection, improve system safety, and keep the load running normally without being affected by harmonics.

[0032] In some embodiments, the harmonic parameters described in step S1 include harmonic content and harmonic distortion rate. Harmonic content and harmonic distortion rate are important parameters for describing the degree of waveform distortion. Harmonic content represents the sum of other frequency components in the waveform except the fundamental wave, while harmonic distortion rate characterizes the degree of waveform distortion by calculating the ratio of all harmonic content to fundamental content. Among them, excessive harmonic content will have an adverse effect on the stability and performance of the power system, such as causing voltage fluctuations, increased current, equipment damage and other problems. At the same time, harmonics may also cause resonance phenomena, further exacerbating the stability problems of the power system. The higher the harmonic distortion rate, the greater the degree of waveform distortion. This will have an adverse effect on the stability and performance of the power system, such as causing voltage waveform distortion, current waveform distortion and other problems. At the same time, high harmonic distortion rate may also cause equipment failure, reduce system efficiency and other problems.

[0033] Reference Figure 2-4 In this embodiment, the system impedance value at the resonant frequency is detected in step S5, and matching the grid-connected virtual impedance based on the system impedance value at the resonant frequency includes the following steps: Measure the effective value of the voltage and current at the grid connection point, and calculate the reactive power of the system based on the effective value of the voltage and current at the grid connection point , , where Point voltage effective value, is the effective value of the grid-connected point current, is the grid-connected point power factor, Reactive power of the system; When parallel resonance occurs, the sum of the hth harmonic admittance is the smallest, and the calculation formula between the fundamental inductive reactance of the system and the fundamental capacitive reactance of the capacitor is: ,Right now: , where is the harmonic order of resonance, is the fundamental inductive reactance of the system, is the fundamental capacitive reactance of the capacitor, according to and , we can calculate and The value of and Reference value of Calculate the system reactive power at the resonant frequency , , , where is the system reactive power at the resonant frequency, is the required harmonic order, and is the system impedance value at the resonant frequency; The system reactive power required to be compensated at the resonant frequency is calculated based on the difference between the system reactive power at the resonant frequency and the system reactive power. , that is, the power required to be output by the energy storage converter, .

[0034] The virtual impedance of the energy storage inverter does not really exist in the physical circuit, but is simulated in the control system of the energy storage inverter through the control algorithm. The principle is to adjust the control strategy so that the energy storage inverter exhibits specific impedance characteristics when connected to the grid, thereby achieving friendly access to the grid and stable operation.

[0035] In this embodiment, the power required to be output by the energy storage converter is obtained and the output power of the energy storage converter is adjusted, so that the grid-connected virtual impedance of the energy storage converter can be changed, thereby changing the system impedance and eliminating or weakening the resonance effect.

[0036] In some embodiments, in step S1, the voltage and current of the grid connection point are sampled, wherein the number of sampling points is 200-300, preferably 256. More sampling points can more accurately reflect the change of the signal in the time domain, thereby obtaining more accurate results in the frequency domain and improving the accuracy of the FFT Fourier transform.

[0037] like Figure 5 As shown, the following is a control system for connecting an anti-resonance energy storage inverter to a grid-connected system provided by an embodiment of the present disclosure. A control system for connecting an anti-resonance energy storage inverter to a grid-connected system and a control method for connecting an anti-resonance energy storage inverter to a grid-connected system in the above-mentioned embodiments belong to the same inventive concept. For details not described in detail in the embodiment of a control system for connecting an anti-resonance energy storage inverter to a grid-connected system, reference can be made to the embodiment of the control method for connecting an anti-resonance energy storage inverter to a grid-connected system mentioned above.

[0038] The control system of an anti-resonance energy storage converter connected to a grid-connected system proposed in this embodiment includes a sampling module, an FFT Fourier transform module, a judgment module, a harmonic cancellation module and an adjustment module, wherein: The sampling module is configured to sample the voltage and current of the grid connection point to obtain the current voltage and current of the grid connection point; The FFT Fourier transform module is configured to perform FFT Fourier transform on the acquired current voltage and current of the grid connection point; The judging module is configured to calculate harmonic parameters based on the result of FFT Fourier transform, and judge whether the harmonic parameters exceed the preset standard value; The harmonic cancellation module is configured to extract characteristic subharmonics based on the results of FFT Fourier transform and invert them to obtain opposite waves when the harmonic parameters exceed the preset standard values, and then perform carrier modulation and PWM pulse width modulation on the opposite waves to inject them into the energy storage system; The adjustment module is configured to detect the system impedance value at the resonant frequency when the harmonic parameter exceeds the preset standard value, match the grid-connected virtual impedance based on the system impedance value at the resonant frequency, and adjust the output parameters of the energy storage converter based on the grid-connected virtual impedance.

[0039] The harmonic parameters include harmonic content and harmonic distortion rate, and the sampling module has 200-300 sampling points, preferably 256.

[0040] An embodiment of the present application also proposes a terminal, including a memory, a processor, a communication unit, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of a control method for connecting an anti-resonance energy storage inverter to a grid-connected system are implemented; the memory, the processor, and the communication unit communicate via one or more buses.

[0041] The processor may include one or more processing units, for example, the processor may include a central processing unit (CPU), an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a memory, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural network processing unit (NPU), etc. Different processing units may be independent devices or integrated into one or more processors.

[0042] The processor can be the nerve center and command center of the terminal. The controller can generate operation control signals according to the instruction operation code and timing signal to complete the control of fetching and executing instructions.

[0043] The memory is used to store the execution instructions of the processor, and the memory can be implemented by any type of volatile or non-volatile storage terminal or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. When the execution instructions in the memory are executed by the processor, the terminal is able to execute some or all of the steps in the above-mentioned control method embodiment of the anti-resonance energy storage converter connected to the grid-connected system.

[0044] The wireless communication function of an electronic device can be realized through an antenna, a wireless communication module, a modem processor, and a baseband processor.

[0045] The wireless communication module can provide wireless communication solutions for electronic devices including wireless LAN, Bluetooth, global navigation satellite system, frequency modulation, short-range wireless communication technology, infrared technology, etc.

[0046] This embodiment further provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of any one of the control methods for connecting an anti-resonance energy storage converter to a grid-connected system as described above are implemented.

[0047] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for connecting an anti-resonance energy storage converter to a grid-connected system, characterized in that: The following steps are involved: S1. Sampling the voltage and current of the grid connection point to obtain the current voltage and current of the grid connection point; performing FFT Fourier transform on the current voltage and current of the grid connection point, calculating the harmonic parameters based on the results of the FFT Fourier transform, and judging whether the harmonic parameters exceed the preset standard values; the grid connection point is the connection point between the energy storage system and the power grid, the energy storage system includes an energy storage converter, a new energy power generation device and a load, and the energy storage converter, the new energy power generation device and the load are connected in parallel; S2. When the harmonic parameter does not exceed the preset standard value, return to step S1; when the harmonic parameter exceeds the preset standard value, extract the characteristic subharmonic based on the result of FFT Fourier transform and invert it to obtain the opposite wave, modulate the opposite wave by carrier wave and perform PWM pulse width modulation to inject it into the energy storage system; S3, sampling the voltage and current of the grid connection point, obtaining the current voltage and current of the grid connection point, performing FFT Fourier transform on the obtained current voltage and current of the grid connection point, calculating the harmonic parameters based on the results of the FFT Fourier transform, and judging whether the harmonic parameters exceed the preset standard values; S4. When the harmonic parameter does not exceed the preset standard value, return to step S1; When the harmonic parameter exceeds the preset standard value, the system impedance value at the resonant frequency is detected, and the system impedance value at the resonant frequency is matched with the grid-connected virtual impedance to obtain the power required to be output by the energy storage inverter, and the energy storage inverter is adjusted based on the power required to be output by the energy storage inverter.

2. A control method for connecting an anti-resonance energy storage converter to a grid-connected system according to claim 1, characterized in that: In step S4, the system impedance value at the resonant frequency is detected, and the power required to be output by the energy storage converter is obtained based on matching the system impedance value at the resonant frequency with the grid-connected virtual impedance, which includes the following steps: Measure the effective value of the voltage and current at the grid connection point, and calculate the reactive power of the system based on the effective value of the voltage and current at the grid connection point , In the formula, Point voltage effective value, is the effective value of the grid-connected point current, is the grid-connected point power factor, Reactive power of the system; Calculate the system reactive power at the resonant frequency , ， ， In the formula, is the system reactive power at the resonant frequency, is the required harmonic order, and is the system impedance value at the resonant frequency; System reactive power based on resonant frequency and the reactive power of the system The difference between the values ​​of and is used to calculate the system reactive power required to be compensated at the resonant frequency. , that is, the power required to be output by the energy storage converter: .

3. A control method for connecting an anti-resonance energy storage converter to a grid-connected system according to claim 1, characterized in that: The harmonic parameters include harmonic content and harmonic distortion rate.

4. A control method for connecting an anti-resonance energy storage converter to a grid-connected system according to claim 1, characterized in that: In step S1 and step S3, the voltage and current of the grid connection point are sampled, wherein the number of sampling points is 200-300.

5. A control system for connecting an anti-resonance energy storage converter to a grid-connected system, characterized in that: It includes a sampling module, an FFT Fourier transform module, a judgment module, a harmonic cancellation module and an adjustment module, wherein: The sampling module is configured to sample the voltage and current of the grid connection point to obtain the current voltage and current of the grid connection point; The FFT Fourier transform module is configured to perform FFT Fourier transform on the acquired current voltage and current of the grid connection point; The judging module is configured to calculate harmonic parameters based on the result of FFT Fourier transform, and judge whether the harmonic parameters exceed the preset standard value; The harmonic cancellation module is configured to return to step S1 when the harmonic parameter does not exceed the preset standard value; when the harmonic parameter exceeds the preset standard value, extract the characteristic subharmonic based on the result of FFT Fourier transform and invert it to obtain the opposite wave, modulate the opposite wave by carrier wave and perform PWM pulse width modulation to inject it into the energy storage system; The adjustment module is configured to return to step S1 when the harmonic parameter does not exceed the preset standard value; when the harmonic parameter exceeds the preset standard value, detect the system impedance value at the resonant frequency, match the system impedance value at the resonant frequency with the grid-connected virtual impedance, obtain the power required to be output by the energy storage inverter, and adjust the energy storage inverter based on the power required to be output by the energy storage inverter.

6. A control system for connecting an anti-resonance energy storage converter to a grid-connected system according to claim 5, characterized in that: The harmonic parameters include harmonic content and harmonic distortion rate.

7. A control system for connecting an anti-resonance energy storage converter to a grid-connected system according to claim 5, characterized in that: The sampling module has 200-300 sampling points.

8. A terminal comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of a control method for connecting an anti-resonance energy storage converter to a grid-connected system as described in any one of claims 1 to 4 are implemented.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, the steps of the control method for connecting an anti-resonance energy storage converter to a grid-connected system as described in any one of claims 1 to 4 are implemented.

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