Impedance measurement method for new energy grid-connected system considering saturation amplitude limiting of controller and related device

Abstract

The invention discloses a new energy grid-connected system impedance measurement method considering controller saturation amplitude limiting and a related device, and belongs to the technical field of new energy grid connection, and the method comprises the following steps: setting a to-be-measured frequency of a voltage disturbance component, and injecting the voltage disturbance component into a new energy grid-connected system; after the new energy grid-connected system is stabilized, sampling to obtain a voltage signal and a current signal; after controller saturation amplitude limiting detection is carried out on the current signal, the voltage signal and the current signal are preprocessed, and a voltage value and a current value under a disturbance frequency and a voltage value and a current value under a coupling frequency are obtained by combining the to-be-detected frequency; and repeating the above steps until two groups of voltage values and current values under the disturbance frequency and voltage values and current values under the coupling frequency are obtained, calculating to obtain a frequency coupling impedance matrix of the new energy unit corresponding to the frequency to be measured, and completing impedance measurement. The method can solve the problem that the existing impedance measurement method neglects the saturation amplitude limiting of the controller.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy grid-connected technology, and in particular relates to a new energy grid-connected system impedance measurement method and related devices taking into account controller saturation limiting. Background Art

[0002] In recent years, the proportion of renewable energy generation such as wind power generation and solar power generation in the power system has been increasing. At the same time, oscillations caused by the interaction between new energy power generation devices and power grids are also common. In particular, when new energy power generation devices operate under weak power grids, the interaction between new energy units and power grid impedance will cause oscillations, affecting the power quality of the new energy power generation system, and even triggering system protection, causing serious economic losses. Among the existing stability analysis methods for new energy systems, the stability analysis method based on impedance model has received widespread attention. From the perspective of impedance, new energy units and power grids can be regarded as sources and loads respectively. When these two parts can operate stably and independently, the interactive stability of the source and load cascade system can be analyzed by combining their input and output impedance models with stability criteria. Since obtaining an accurate impedance model is a prerequisite for analyzing accurate stability analysis results, studying the impedance modeling of new energy units is a technical difficulty that needs to be solved urgently. The impedance models commonly used in the stability analysis of new energy units are mainly divided into two categories, namely dq axis impedance model and sequence impedance model. The sequence impedance model is an impedance model established on the abc axis through the harmonic linearization method. The sequence impedance model has a clear physical meaning and is very easy to obtain through measurement. It is also applicable to other working conditions such as three-phase imbalance and has strong scalability. Therefore, the stability analysis of new energy units based on the sequence impedance model has been widely used.

[0003] Common impedance modeling methods currently include analytical method and measurement method. The analytical method requires understanding the internal control strategy and detailed parameters of the new energy unit, but most of the devices in actual operation are black / gray boxes, and it is difficult to obtain their detailed system parameters, so it is difficult to establish their analytical impedance model through theoretical analysis. The impedance modeling method based on measurement can obtain impedance data by injecting small signal disturbances into the new energy unit without understanding the internal control and parameters of the new energy unit.

[0004] Different from the impedance measurement of traditional passive equipment, new energy units have obvious nonlinearity, and impedance measurement must be based on a stable operating point. Therefore, the impedance measurement of new energy units needs to be measured online. On the basis of the stable operation of the grid-connected system of new energy units, the impedance is calculated using the injected or inherent harmonic signal of the system. The current impedance measurement method may cause the controller to saturate and limit due to the large disturbance signal during measurement, resulting in measurement errors. Summary of the invention

[0005] The purpose of the present invention is to provide a new energy grid-connected system impedance measurement method and related devices taking into account controller saturation limiting, so as to solve the problem that the existing impedance measurement method ignores the controller saturation limiting.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, a method for measuring impedance of a new energy grid-connected system considering controller saturation limiting is provided, characterized in that it comprises the following steps: The frequency to be measured of the voltage disturbance component is set, and the voltage disturbance component is injected into the renewable energy grid-connected system; After the new energy grid-connected system is stable, the voltage and current signals are sampled and obtained; After the controller saturation limit detection is performed on the current signal, Preprocessing the voltage signal and the current signal and obtaining the voltage value and the current value at the disturbance frequency and the voltage value and the current value at the coupling frequency in combination with the frequency to be measured; Repeat the above steps until two sets of voltage and current values ​​at the disturbance frequency and the voltage and current values ​​at the coupling frequency are obtained, then calculate the frequency coupling impedance matrix of the new energy unit corresponding to the frequency to be measured to complete the impedance measurement.

[0007] In some embodiments, the voltage disturbance component is a positive sequence voltage disturbance component or a negative sequence voltage disturbance component; When the positive sequence voltage disturbance component whose frequency to be measured is the disturbance frequency is injected for the first time, the negative sequence voltage disturbance component whose coupling frequency corresponds to the disturbance frequency is injected for the second time; When the negative-sequence voltage disturbance component whose frequency to be measured is the disturbance frequency is injected for the first time, the positive-sequence voltage disturbance component whose frequency to be measured is the coupling frequency corresponding to the disturbance frequency is injected for the second time.

[0008] In some implementations, after the new energy grid-connected system is stabilized, the voltage disturbance component signal is sampled to obtain a voltage signal, and the inverter output current after the voltage disturbance component is injected is sampled to obtain a current signal.

[0009] In some implementations, the step of performing controller saturation limiting detection on the current signal specifically includes: Perform Fourier analysis on the current signal. If there is a frequency Hz and Hz harmonics, the controller will be saturated and limited, and the voltage disturbance component will be reset to be smaller than the current voltage disturbance component and then injected into the new energy grid-connected system; otherwise, the controller will not be saturated and limited, and the voltage signal and current signal will be pre-processed; wherein, is the frequency to be measured, is the fundamental frequency.

[0010] In some embodiments, the step of preprocessing the voltage signal and the current signal and obtaining the voltage value and the current value at the disturbance frequency and the voltage value and the current value at the coupling frequency in combination with the measured frequency specifically includes: After preprocessing the voltage signal and the current signal by using the windowed FFT method and the spectral line interpolation method, the voltage value at the disturbance frequency and the voltage value at the coupling frequency in the preprocessed voltage signal are extracted by Fourier transform in combination with the frequency to be measured, and the current value at the disturbance frequency and the current value at the coupling frequency in the preprocessed current signal are extracted at the same time.

[0011] In some implementations, the step of injecting a voltage disturbance component into the renewable energy grid-connected system specifically includes: injecting a voltage disturbance component into a common connection point or a transmission line in the renewable energy grid-connected system.

[0012] In a second aspect, a new energy grid-connected system impedance measurement system considering controller saturation limiting includes: The harmonic injection module is used to set the frequency to be measured of the voltage disturbance component and inject the voltage disturbance component into the renewable energy grid-connected system; A signal sampling module is used to sample and obtain voltage and current signals after the renewable energy grid-connected system is stable; A saturation limit detection module, used for performing controller saturation limit detection on the current signal; The impedance measurement module is used to preprocess the voltage signal and the current signal and obtain the voltage value and the current value at the disturbance frequency and the voltage value and the current value at the coupling frequency in combination with the frequency to be measured. According to the two groups of voltage values ​​and current values ​​at the disturbance frequency and the voltage value and current value at the coupling frequency, the frequency coupling impedance matrix of the new energy unit corresponding to the frequency to be measured is calculated to complete the impedance measurement.

[0013] In a third aspect, an electronic device comprises a memory, a processor, and a computer program stored in the memory and executable in the processor, wherein when the processor executes the computer program, the steps of the impedance measurement method of a new energy grid-connected system taking into account controller saturation limiting are implemented.

[0014] In a fourth aspect, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the impedance measurement method of a new energy grid-connected system considering controller saturation limiting are implemented.

[0015] In a fifth aspect, a computer program product is provided, the computer product comprising a computer program, wherein when the computer program is executed by a processor, the steps of the impedance measurement method of a new energy grid-connected system taking into account controller saturation limiting are implemented.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for measuring impedance of a new energy grid-connected system taking into account controller saturation limiting. After injecting a voltage disturbance component, a voltage signal and a current signal are sampled after the new energy grid-connected system is stable; after the current signal is subjected to controller saturation limiting detection, the voltage signal and the current signal are preprocessed and combined with the measured frequency to obtain the voltage value and the current value at the disturbance frequency, as well as the voltage value and the current value at the coupling frequency, and finally the frequency coupling impedance matrix of the new energy unit corresponding to the measured frequency is calculated to complete the impedance measurement. This method overcomes the shortcomings of the existing impedance measurement method, and can detect whether the controller is saturated and limited without adding additional detection equipment, thereby reducing the impedance measurement cost, improving the impedance measurement accuracy, and improving the impedance measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of an impedance measurement system for a new energy grid-connected system taking into account controller saturation limiting provided by an embodiment of the present invention; Figure 2 A flow chart of a method for measuring impedance of a new energy grid-connected system taking into account controller saturation limiting provided by an embodiment of the present invention; Figure 3 is the d-axis signal when no disturbance signal is injected in the saturation limiting detection in the embodiment of the present invention; Figure 4 It is the d-axis signal after the disturbance signal is injected in the saturation limiting detection in the embodiment of the present invention; Figure 5 It is the d-axis signal that triggers the saturation limiting of the controller in the saturation limiting detection in the embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings, and the described content is intended to explain the present invention rather than to limit it.

[0019] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, systems, products or apparatus.

[0020] Before introducing the embodiments, the relevant terms are introduced first: (1) Frequency coupling effect: In the traditional impedance modeling of grid-connected inverters, a sinusoidal voltage disturbance of a certain frequency and a certain phase sequence at the grid connection point is considered to only cause a sinusoidal current response of the same frequency and the same phase sequence. However, if the dq axis control in the grid-connected inverter is asymmetric, applying a voltage disturbance of a certain frequency to it will not only cause a current response component of the same frequency, but also another current response component of a different frequency. This phenomenon is called the frequency coupling characteristic of the grid-connected inverter. The relationship between the voltage disturbance and the current response component is: Assuming that the voltage disturbance is a positive sequence and the frequency is , then the disturbance current component is positive sequence and the frequency is , the coupled current component is negative sequence and the frequency is , is the fundamental frequency.

[0021] (2) Controller saturation limiting: In actual engineering applications, in order to protect the grid-connected inverter, there are limiting links in multiple links of the control loop, especially the integral link. For the grid-connected inverter, after the saturation limiting is triggered, the system performance will degrade or even become unstable.

[0022] (3) Grid connection point: In actual engineering applications, in order to protect the grid-connected inverter, there are limiting links in multiple links of the control loop, especially the integral link. For the grid-connected inverter, after the saturation limit is triggered, the system performance will degrade or even become unstable.

[0023] (4) Point of Common Coupling (PCC): The point where the new energy grid-connected system is connected to the public power grid.

[0024] (5) Window function: In fast Fourier analysis, in order to reduce or eliminate spectral capacity leakage, different truncation functions can be used to truncate the signal. This truncation function is called a window function.

[0025] (6) Spectral line interpolation method: The spectrum is obtained using fast Fourier transform. The interpolation correction formula is derived based on the information of the leaked spectral lines near each frequency point to obtain the amplitude, frequency, and phase information of the signal.

[0026] The following is a detailed introduction to the content of this embodiment in conjunction with the accompanying drawings: The current impedance measurement method requires the injection of a disturbance signal, but the selection of the range of the disturbance signal has always been a difficult problem. If the disturbance signal is too small, the voltage and current disturbance frequency and coupling frequency signal content at the PCC are low; if the disturbance signal is too large, it may cause controller saturation limiting, resulting in measurement errors. However, the existing impedance measurement method does not consider the situation of controller saturation limiting. Therefore, the impedance measurement method has the disadvantage of poor measurement accuracy due to ignoring the controller saturation limiting.

[0027] like Figure 2 As shown, this embodiment provides a method for measuring impedance of a new energy grid-connected system taking into account controller saturation limiting, comprising the following steps: S1, all frequencies to be measured for impedance measurement; S2, injects the frequency to be tested into the common connection point through the harmonic injection module. The positive sequence voltage disturbance component, the disturbance frequency and coupling frequency The relationship is , is the fundamental frequency; S3, after the system is stable, the positive sequence voltage disturbance component is sampled through the signal sampling module to obtain the voltage signal , and sample the inverter output current after injecting the positive sequence voltage disturbance component to obtain the current signal ; S4, the current signal is detected by a saturation limit detection module. Controller saturation limit detection: current signal Perform Fourier analysis. If there is a frequency Hz and If the harmonics are greater than Hz, it is determined that the controller has saturated limiting. After the voltage value of the positive sequence voltage disturbance component is readjusted to be less than the current voltage value of the positive sequence voltage disturbance component, S2 to S4 are repeated until it is determined that the controller has not saturated limiting, and then S5 is performed; S5: The voltage signal is processed by the data processing module and current signal Preprocessing is performed using windowed FFT and spectral line interpolation, and the disturbance frequency is extracted through Fourier transform The voltage value under , Current value and coupling frequency The voltage value under and current value , expressed as the following formula (1): (1) S6: The frequency to be tested is injected into the transmission line through the harmonic injection module. The negative sequence voltage disturbance component.

[0028] S7: After the system is stable, the negative sequence voltage disturbance component is sampled through the signal sampling module to obtain the voltage signal , and sample the inverter output current after injecting the negative sequence voltage disturbance component to obtain the current signal ; S8: The current signal is detected by a saturation limit detection module. Controller saturation limit detection: current signal Perform Fourier analysis. If there is a frequency Hz and If the harmonics are Hz, it is determined that the controller has saturated amplitude limiting, and the voltage value of the negative sequence voltage disturbance component is readjusted to be smaller than the current voltage value of the negative sequence voltage disturbance component, and S6 to S8 are repeated until it is determined that the controller has not saturated amplitude limiting, and then S9 is performed; S9: The voltage signal is processed by the data processing module and current signal Preprocessing is performed using windowed FFT and spectral line interpolation, and the disturbance frequency is extracted through Fourier transform The voltage value under , Current value and coupling frequency The voltage value under and current value , expressed as the following formula (2): (2) S10: Combining equations (1) and (2) to obtain equation (3): (3) The impedance calculation and monitoring module calculates each element in the frequency coupling impedance matrix of the new energy unit according to formula (3) as the following formula (4), completing the impedance measurement.

[0029] (4) The above saturation limit detection is described in detail below. During the impedance measurement process, this embodiment takes into account the saturation limit of the current controller output and detects whether the controller has saturation limit, so as to reduce the impedance measurement error.

[0030] like Figure 3 As shown, taking the d-axis signal as an example, the disturbance frequency is 26Hz. When no disturbance is injected, the d-axis signal frequency component only contains the DC component. Figure 4 As shown in Figure 1, after the disturbance is injected, the spectrum contains a frequency component of 26 Hz through Fourier analysis. Figure 5As shown in Figure 1, when the controller triggers the saturation limiter, the spectrum will contain frequency components of 26 Hz and its multiples.

[0031] The inverter is controlled in the dq coordinate system. Park transformation is required from the three-phase stationary coordinate system to the dq coordinate system. The transformation formula is:

[0032] Assume that the expressions of grid voltage and current after voltage disturbance injection are:

[0033]

[0034] set up , the dq axis voltage obtained after the three-phase voltage is transformed by Park can be expressed as:

[0035] Transforming the above formula into the frequency domain yields:

[0036]

[0037] It can be seen from the above formula that the frequency of the three-phase voltage will shift after Park transformation. After the transformation, the signal in the dq axis will reduce the frequency of the positive sequence signal in the original stationary abc coordinate system by one fundamental frequency, and increase the frequency of the negative sequence signal by one fundamental frequency.

[0038] In summary, after the current is transformed by Park, the disturbance frequency With fundamental frequency Perform convolution to produce The frequency component of the controller generates a 2-fold frequency after the saturation limit is triggered. The frequency component of will be generated when it is inversely transformed by Park and Therefore, the sampling current is analyzed by fast Fourier analysis. and The frequency component is detected to determine whether the controller is saturated and limited.

[0039] like Figure 1 As shown, this embodiment also provides a new energy grid-connected system impedance measurement system considering controller saturation limiting, including: The harmonic injection module is used to set the frequency to be measured of the voltage disturbance component, inject the voltage disturbance component into the renewable energy grid-connected system, and sample and obtain the voltage signal and current signal after the renewable energy grid-connected system is stable; A signal sampling module is used to sample and obtain voltage and current signals after the renewable energy grid-connected system is stable; A saturation limit detection module, used for performing controller saturation limit detection on the current signal; The impedance measurement module includes a data processing module and an impedance calculation and monitoring module. A data processing module, used for preprocessing the voltage signal and the current signal; The impedance calculation and monitoring module is used to obtain the voltage value and current value at the disturbance frequency and the voltage value and current value at the coupling frequency according to the preprocessed voltage signal and current signal and in combination with the frequency to be measured, and calculate the frequency coupling impedance matrix of the new energy unit corresponding to the frequency to be measured according to the two groups of voltage values ​​and current values ​​at the disturbance frequency and the voltage value and current value at the coupling frequency to complete the impedance measurement.

[0040] The division of modules in the embodiments of the present invention is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, each functional module in each embodiment of the present invention may be integrated into one processor, or may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated modules may be implemented in the form of hardware or in the form of software functional modules.

[0041] In this embodiment, a computer device is also provided, which includes a processor and a memory, the memory is used to store a computer program (in this embodiment, the computer program includes a calculation component and an iteration component, which can perform model calculation and model update), the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of a new energy grid-connected system impedance measurement method considering controller saturation limiting.

[0042] This embodiment also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It is understandable that the computer-readable storage medium here can include both built-in storage media in a computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of a new energy grid-connected system impedance measurement method considering controller saturation limiting in the above embodiment.

[0043] This embodiment further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the corresponding steps of the impedance measurement method of a new energy grid-connected system considering controller saturation limiting in the above embodiment are implemented.

[0044] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0045] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0046] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0047] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for measuring impedance of a new energy grid-connected system considering controller saturation limiting, characterized in that: The following steps are involved: The frequency to be measured of the voltage disturbance component is set, and the voltage disturbance component is injected into the renewable energy grid-connected system; After the new energy grid-connected system is stable, the voltage and current signals are sampled and obtained; After the controller saturation limit detection is performed on the current signal, Preprocessing the voltage signal and the current signal and obtaining the voltage value and the current value at the disturbance frequency and the voltage value and the current value at the coupling frequency in combination with the frequency to be measured; Repeat the above steps until two sets of voltage and current values ​​at the disturbance frequency and the voltage and current values ​​at the coupling frequency are obtained, then calculate the frequency coupling impedance matrix of the new energy unit corresponding to the frequency to be measured to complete the impedance measurement.

2. A method for measuring impedance of a new energy grid-connected system considering controller saturation limiting according to claim 1, characterized in that: The voltage disturbance component is a positive sequence voltage disturbance component or a negative sequence voltage disturbance component; When the positive sequence voltage disturbance component whose frequency to be measured is the disturbance frequency is injected for the first time, the negative sequence voltage disturbance component whose coupling frequency corresponds to the disturbance frequency is injected for the second time; When the negative-sequence voltage disturbance component whose frequency to be measured is the disturbance frequency is injected for the first time, the positive-sequence voltage disturbance component whose frequency to be measured is the coupling frequency corresponding to the disturbance frequency is injected for the second time.

3. The impedance measurement method of a new energy grid-connected system considering controller saturation limiting according to claim 1 is characterized in that: After the new energy grid-connected system is stable, the voltage disturbance component is sampled to obtain a voltage signal, and the inverter output current after the voltage disturbance component is injected is sampled to obtain a current signal.

4. The impedance measurement method of a new energy grid-connected system considering controller saturation limiting according to claim 1 is characterized in that: The step of performing controller saturation limiting detection on the current signal specifically includes: Perform Fourier analysis on the current signal. If there is a frequency Hz and Hz harmonics, the controller will be saturated and limited, and the voltage disturbance component will be reset to be smaller than the current voltage disturbance component and then injected into the new energy grid-connected system; otherwise, the controller will not be saturated and limited, and the voltage signal and current signal will be pre-processed; wherein, is the frequency to be measured, is the fundamental frequency.

5. The impedance measurement method of a new energy grid-connected system considering controller saturation limiting according to claim 1 is characterized in that: The step of preprocessing the voltage signal and the current signal and obtaining the voltage value and the current value at the disturbance frequency and the voltage value and the current value at the coupling frequency in combination with the measured frequency specifically includes: After preprocessing the voltage signal and the current signal by using the windowed FFT method and the spectral line interpolation method, the voltage value at the disturbance frequency and the voltage value at the coupling frequency in the preprocessed voltage signal are extracted by Fourier transform in combination with the frequency to be measured, and the current value at the disturbance frequency and the current value at the coupling frequency in the preprocessed current signal are extracted at the same time.

6. A method for measuring impedance of a new energy grid-connected system considering controller saturation limiting according to claim 1, characterized in that: The step of injecting a voltage disturbance component into the renewable energy grid-connected system specifically includes: injecting a voltage disturbance component into a common connection point or a transmission line in the renewable energy grid-connected system.

7. A new energy grid-connected system impedance measurement system considering controller saturation limiting, characterized in that: include: The harmonic injection module is used to set the frequency to be measured of the voltage disturbance component and inject the voltage disturbance component into the renewable energy grid-connected system; A signal sampling module is used to sample and obtain voltage and current signals after the renewable energy grid-connected system is stable; A saturation limit detection module, used for performing controller saturation limit detection on the current signal; The impedance measurement module is used to preprocess the voltage signal and the current signal and obtain the voltage value and the current value at the disturbance frequency and the voltage value and the current value at the coupling frequency in combination with the frequency to be measured. According to the two groups of voltage values ​​and current values ​​at the disturbance frequency and the voltage value and current value at the coupling frequency, the frequency coupling impedance matrix of the new energy unit corresponding to the frequency to be measured is calculated to complete the impedance measurement.

8. An electronic device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable in the processor, wherein when the processor executes the computer program, the steps of a method for measuring impedance of a new energy grid-connected system taking into account controller saturation limiting as described in any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of a method for measuring impedance of a new energy grid-connected system taking into account controller saturation limiting as described in any one of claims 1 to 6 are implemented.

10. A computer program product, the computer product comprising a computer program, characterized in that: When the computer program is executed by a processor, the steps of a method for measuring impedance of a new energy grid-connected system taking into account controller saturation limiting as described in any one of claims 1 to 6 are implemented.

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