Impedance Scanning Test Method and Device for Energy Storage System Based on Grid-Connected Characteristics

Abstract

The present invention discloses a method and device for impedance scanning test of an energy storage system based on grid connection characteristics, which relates to the technical field of electric energy storage systems. First, the energy storage system is connected to the power grid through a power electronic grid-connected converter. By continuously analyzing the connection process and then performing grid connection modulation on the power electronic grid-connected converter, it helps to enhance the regulation ability and response speed of the energy storage system in the power grid. Then, fluctuation detection is performed on the modulated grid-connected energy storage system, and then the grid-connected energy storage system is configured, and impedance scanning test execution parameters are processed to optimize the performance of the grid-connected energy storage system. Finally, impedance scanning test is performed on the configured grid-connected energy storage system in combination with the impedance scanning test execution parameters, and power stability control is performed on the grid-connected energy storage system, which can comprehensively evaluate the electrical characteristics of the energy storage system and improve the stability and safety of the energy storage system in the power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical energy storage systems, and specifically to a method and device for impedance scanning test of an energy storage system based on grid connection characteristics. Background Art

[0002] In the field of energy storage system detection technology, with the increasing demand of the power system for efficient, stable and sustainable energy supply, energy storage technology plays an increasingly important role in power dispatching, load balancing and system stability. In a grid-connected system, the state and performance of energy storage devices directly affect the safety and reliability of the power grid. The damping characteristics of the energy storage system have an important impact on its grid connection process and stability. By accurately measuring the impedance response of the energy storage system at different frequencies, the electrical characteristics, performance degradation and potential faults of the energy storage device can be effectively identified, thereby improving the management and monitoring level of the power grid for the energy storage device.

[0003] The prior art, such as a battery energy storage system grid connection control method and device disclosed in the invention patent publication with the publication number of CN112467799B, the method includes: in response to the acquired active power and reactive power, performing difference compensation on the active power and reactive power; inputting the active current reference value output by the current controller and the reactive current reference value output by the current controller into the current limit controller based on the charge and discharge control strategy; performing Park transformation on the port current to obtain the real-time value of the active current and the real-time value of the reactive current; inputting the active current difference and the reactive current difference into the PI controller, and obtaining the three-phase voltage reference value based on the inverse Park transformation; comparing the three-phase voltage reference value with the modulation voltage to obtain the modulation wave. Compensating and controlling the controller based on the error value, and comparing the three-phase voltage reference value with the modulation voltage to obtain the modulation wave, and then controlling the switching device of the power converter.

[0004] The prior art, such as a method, device and system for detecting the grid connection performance of an electrochemical energy storage system in a new energy power station based on multi-point synchronous testing, disclosed in the invention patent publication with the publication number of CN115986797B, belongs to the field of new energy power stations, and is used to solve the problem that the grid connection success rate is reduced by blindly performing grid connection operations without analyzing the compatibility between the energy storage system and the distribution network. It includes an energy storage determination module, a power quality analysis module, an intelligent grid connection module and a simulation analysis module. The power quality analysis module is used to analyze the energy storage quality of the electrochemical energy storage system, the energy storage determination module is used to determine the energy storage quality of the electrochemical energy storage system, the simulation analysis module is used to simulate and analyze the working state of the electrochemical energy storage system after grid connection, and the intelligent grid connection module is used to intelligently connect the electrochemical energy storage system to the distribution network.

[0005] It is found that in the current field of energy storage system grid connection technology, only power compensation and grid connection adaptability are usually analyzed. However, there will be problems of grid instability during the process of the energy storage system connecting to the grid, which will cause the data acquisition in the impedance scanning test of the energy storage system to be interfered by grid fluctuations. At the same time, the grid interference also requires the grid-connected energy storage system to have certain levels and accuracies for actual impedance scanning tests. The current technology only analyzes from power compensation and grid connection adaptability, which not only affects the accuracy and stability of the test results, cannot truly reflect the dynamic response characteristics of the energy storage system, but also may lead to problems such as increased grid power fluctuations and harmonic distortion, affecting the safety and reliability of the entire power system. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a method and device for impedance scanning test of an energy storage system based on grid connection characteristics, which can effectively solve the problems involved in the above background technology.

[0007] To achieve the above objectives, the first aspect of the present invention is realized through the following technical solutions: A method for impedance scanning test of an energy storage system based on grid connection characteristics, including that the energy storage system is connected to the grid through a power electronic grid connection converter, and by continuously analyzing the connection process, grid connection characteristic parameters of the energy storage system are obtained, and then grid connection modulation is performed on the power electronic grid connection converter.

[0008] Fluctuation detection is performed on the modulated grid-connected energy storage system, and then the grid fluctuation result of the grid-connected energy storage system is analyzed. According to the grid fluctuation result of the grid-connected energy storage system, the grid-connected energy storage system is configured, and impedance scanning test execution parameters are processed, and at the same time, an impedance scanning test start signal is sent.

[0009] The central controller receives the impedance scanning test start signal, and performs an impedance scanning test on the configured grid-connected energy storage system in combination with the impedance scanning test execution parameters, obtains the damping characteristic information of the grid-connected energy storage system, and sends the damping characteristic information of the grid-connected energy storage system to the central control platform.

[0010] The central control platform receives the damping characteristic information of the grid-connected energy storage system, performs power stability control on the grid-connected energy storage system, and sends the control result to the mobile terminal for display.

[0011] Further, the process of performing grid connection modulation on the power electronic grid connection converter is as follows: The grid connection characteristic parameters of the energy storage system include the frequency fluctuation coefficient of the grid within a preset monitoring period, the number of current harmonic distortions of the grid, the electromagnetic interference coefficient of the energy storage system, and the average charge-discharge efficiency of the energy storage system.

[0012] Based on the grid-connected characteristic parameters of the energy storage system, the grid-connected eigenvalue of the energy storage system is obtained, and the grid-connected eigenvalue of the energy storage system is used to quantify the stability degree of the energy storage system during the process of connecting to the power grid.

[0013] According to the grid-connected eigenvalue of the energy storage system, the output power adjustment value of the power electronic grid-connected converter is matched. The output power of the current power electronic grid-connected converter is added to the output power adjustment value of the power electronic grid-connected converter to obtain the target execution value of the output power of the power electronic grid-connected converter. The power electronic grid-connected converter is modulated for grid connection according to the target execution value of the output power of the power electronic grid-connected converter.

[0014] Further, the process of detecting the fluctuation of the grid-connected energy storage system after modulation is as follows: detecting the fluctuation of the grid-connected energy storage system after modulation to obtain the fluctuation detection data of the grid-connected energy storage system. The fluctuation detection data of the grid-connected energy storage system includes the voltage fluctuation coefficient, frequency fluctuation coefficient, phase offset coefficient, and current peak value of the grid-connected energy storage system within a preset fluctuation monitoring period.

[0015] Performing comprehensive analysis on the fluctuation detection data of the grid-connected energy storage system to obtain the fluctuation detection evaluation value of the grid-connected energy storage system. The fluctuation detection evaluation value of the grid-connected energy storage system is used to comprehensively quantify the fluctuation degree of the grid-connected energy storage system.

[0016] Further, the process of analyzing the grid fluctuation result of the grid-connected energy storage system is as follows: the grid fluctuation result of the grid-connected energy storage system includes abnormal grid fluctuation and normal grid fluctuation.

[0017] Extracting the fluctuation detection evaluation threshold of the grid-connected energy storage system stored in the impedance scan test database, comparing the fluctuation detection evaluation value of the grid-connected energy storage system with the fluctuation detection evaluation threshold of the grid-connected energy storage system. If the fluctuation detection evaluation value of the grid-connected energy storage system is higher than the fluctuation detection evaluation threshold of the grid-connected energy storage system, the grid fluctuation result of the grid-connected energy storage system is marked as abnormal grid fluctuation, otherwise the grid fluctuation result of the grid-connected energy storage system is marked as normal grid fluctuation.

[0018] Further, the process of configuring the grid-connected energy storage system according to the grid fluctuation result of the grid-connected energy storage system is as follows: extracting the grid fluctuation result of the grid-connected energy storage system. If the grid fluctuation result of the grid-connected energy storage system is normal grid fluctuation, continue to configure the grid-connected energy storage system with the current phase-locked loop integration gain of the grid-connected energy storage system.

[0019] If the grid fluctuation result of the grid-connected energy storage system is abnormal grid fluctuation, then add the current phase-locked loop integral gain of the grid-connected energy storage system to the set supplementary value of the phase-locked loop integral gain of the grid-connected energy storage system to obtain the target achievement value of the phase-locked loop integral gain of the grid-connected energy storage system, and adjust the current phase-locked loop integral gain of the grid-connected energy storage system to the target achievement value of the phase-locked loop integral gain of the grid-connected energy storage system for configuration.

[0020] Further, the impedance scan test execution parameters are obtained through processing and an impedance scan test start signal is sent simultaneously. The specific process is as follows: Extract the grid fluctuation result of the grid-connected energy storage system. If the grid fluctuation result of the grid-connected energy storage system is normal grid fluctuation, then set the impedance scan test standard parameters as the impedance scan test execution parameters.

[0021] If the grid fluctuation result of the grid-connected energy storage system is abnormal grid fluctuation, then record the difference between the fluctuation detection and evaluation value of the grid-connected energy storage system and the fluctuation detection and evaluation threshold value of the grid-connected energy storage system as the impedance scan test comparison value, and match the impedance scan test execution parameters according to the impedance scan test comparison value.

[0022] The impedance scan test execution parameters include the scan frequency of the impedance scan test, the injection signal amplitude of the impedance scan test, and the sampling frequency of the impedance scan test.

[0023] Further, the impedance scan test is performed on the configured grid-connected energy storage system in combination with the impedance scan test execution parameters. The specific process is as follows: The central controller adjusts the impedance scan test parameters of the energy storage system impedance scan test device to the impedance scan test execution parameters, and performs an impedance scan test on the configured grid-connected energy storage system through the energy storage system impedance scan test device to obtain the impedance scan test parameters of the grid-connected energy storage system. The impedance scan test parameters of the grid-connected energy storage system include the actual injection signal amplitude during the impedance scan test within the preset scan monitoring period, the environmental deviation coefficient of the impedance scan test, the impedance amplitude fluctuation coefficient of the grid-connected energy storage system, and the voltage fluctuation coefficient of the grid-connected energy storage system.

[0024] Based on the impedance scan test parameters of the grid-connected energy storage system, the damping characteristic analysis index value of the grid-connected energy storage system is obtained. The damping characteristic analysis index value of the grid-connected energy storage system is used to quantify the ability of the grid-connected energy storage system to suppress grid oscillations.

[0025] Further, the damping characteristic information of the grid-connected energy storage system is obtained. The specific process is as follows: Import the damping characteristic analysis index value of the grid-connected energy storage system into the damping characteristic analysis model to obtain the damping characteristic information of the grid-connected energy storage system.

[0026] Mark the damping characteristic analysis index value of the grid-connected energy storage system as .

[0027] The damping characteristic analysis first threshold and the damping characteristic analysis second threshold in the statistical damping characteristic analysis model are respectively marked as , .

[0028] After the damping characteristic analysis model is processed, if , the damping characteristic information of the grid-connected energy storage system is marked as normal damping characteristic.

[0029] like , the damping characteristic information of the grid-connected energy storage system is marked as abnormal damping characteristics.

[0030] like , the damping characteristic information of the grid-connected energy storage system is marked as a damping characteristic fault.

[0031] Furthermore, the power stability control of the grid-connected energy storage system is specifically carried out as follows: extracting damping characteristic information of the grid-connected energy storage system; if the damping characteristic information of the grid-connected energy storage system indicates that the damping characteristic is normal, continuing to perform power stability control with the current operation mode of the grid-connected energy storage system; if the damping characteristic information of the grid-connected energy storage system indicates that the damping characteristic is abnormal, adjusting the current operation mode of the grid-connected energy storage system to the frequency regulation mode; if the damping characteristic information of the grid-connected energy storage system indicates that the damping characteristic is faulty, adjusting the current operation mode of the grid-connected energy storage system to the frequency and voltage regulation mode.

[0032] The second aspect of the present invention provides an apparatus for an impedance scanning test method for an energy storage system based on grid-connected characteristics, further comprising: a processor, and a memory and a network interface connected to the processor; the network interface is connected to a non-volatile memory in a server; when the processor is running, it retrieves a computer program from the non-volatile memory through the network interface, and runs the computer program through the memory to execute the above-mentioned impedance scanning test method for an energy storage system based on grid-connected characteristics.

[0033] The present invention has the following beneficial effects:

[0034] (1) The present invention provides an impedance scanning test method for an energy storage system based on grid-connected characteristics. First, the process of connecting the energy storage system to the grid is continuously analyzed, and then the power electronic grid-connected converter is modulated for grid connection, which helps to improve the stability of the system connection process. Then, the grid-connected energy storage system is subjected to fluctuation detection and configured for the grid-connected energy storage system, which helps to improve the overall performance and response speed of the energy storage system. Finally, the grid-connected energy storage system is subjected to power stability control, which can enhance the reliability of the energy storage system in the grid.

[0035] (2) By processing to obtain the impedance scanning test execution parameters, the present invention can optimize the control method of the grid-connected energy storage system, reduce the power fluctuation and harmonic distortion caused by grid fluctuations, improve the safety and reliability of the power system. According to the grid fluctuation results of the grid-connected energy storage system, the impedance scanning test execution parameters can be further analyzed, which can improve the level and accuracy of the actual impedance scanning test and reduce the influence of grid fluctuation interference on data acquisition during the impedance scanning test of the energy storage system.

[0036] (3) By performing grid connection modulation on the power electronic grid-connected converter, the present invention can ensure that when the energy storage system is connected to the grid, the output power is adjusted according to the real-time state of the grid, thereby improving the compatibility and response speed of the system, reducing the influence of grid fluctuations on the energy storage system, effectively suppressing the negative impacts brought by grid fluctuations or changes in the state of the energy storage system, ensuring the smoothness and reliability of power output, and reducing the occurrence of grid faults.

[0037] (4) By configuring the grid-connected energy storage system according to the grid fluctuation results of the grid-connected energy storage system, the present invention can achieve real-time monitoring and dynamic adjustment of grid fluctuations, help to quickly respond to grid anomalies, reduce the influence of grid fluctuations on the impedance scanning test process of the energy storage system. When detecting abnormal grid fluctuations, the energy storage system will automatically adjust the phase-locked loop integral gain to enhance the adaptability of the system and effectively reduce the negative impact of fluctuations on the grid.

[0038] (5) By receiving the damping characteristic information of the grid-connected energy storage system to perform power stability control on the grid-connected energy storage system, the present invention can ensure that the system can still operate stably under various conditions. It can not only improve the response ability of the grid-connected energy storage system under load fluctuations or emergencies, but also reduce the power supply interruption caused by the abnormality of the grid-connected energy storage system. By timely adjusting the operation mode of the energy storage system, precise and stable control of the power system can be achieved, which helps to improve the overall anti-interference ability of the grid-connected energy storage system.

[0039] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic flowchart of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] Please refer to Figure 1 As shown, a technical solution is provided in the first aspect of the embodiment of the present invention: an impedance scanning test method for an energy storage system based on grid connection characteristics, including that the energy storage system is connected to the grid through a power electronic grid-connected converter, and by continuously analyzing the connection process, grid connection characteristic parameters of the energy storage system are obtained, and then grid connection modulation is performed on the power electronic grid-connected converter.

[0043] Fluctuation detection is performed on the modulated grid-connected energy storage system, and then the grid fluctuation result of the grid-connected energy storage system is analyzed. According to the grid fluctuation result of the grid-connected energy storage system, the grid-connected energy storage system is configured, and impedance scanning test execution parameters are processed, and at the same time, an impedance scanning test start signal is sent.

[0044] It should be explained that the energy storage system refers to an independent system before being connected to the grid, and the grid-connected energy storage system refers to the system after the energy storage system is connected to the grid through a power electronic grid-connected converter, and can perform bidirectional energy flow according to the dispatching of the grid.

[0045] The central controller receives the impedance scanning test start signal, combines the impedance scanning test execution parameters to perform an impedance scanning test on the configured grid-connected energy storage system, obtains the damping characteristic information of the grid-connected energy storage system, and sends the damping characteristic information of the grid-connected energy storage system to the central control platform.

[0046] The central control platform receives the damping characteristic information of the grid-connected energy storage system, performs power stability control on the grid-connected energy storage system, and sends the control result to the mobile terminal for display.

[0047] Specifically, grid connection modulation is performed on the power electronic grid-connected converter. The specific process is as follows: the grid connection characteristic parameters of the energy storage system include the frequency fluctuation coefficient of the grid within a preset monitoring period, the number of current harmonic distortions of the grid, the electromagnetic interference coefficient of the energy storage system, and the average charge and discharge efficiency of the energy storage system.

[0048] It should be noted that the frequency fluctuation coefficient of the power grid reflects the stability of the power grid frequency within a preset monitoring period. The power grid frequency at multiple moments within the preset monitoring period is measured by a power quality analyzer, and then the standard deviation and average value of the power grid frequency within the preset monitoring period are obtained. The ratio of the standard deviation and average value of the power grid frequency within the preset monitoring period is used as the frequency fluctuation coefficient of the power grid. The number of current harmonic distortions in the power grid reflects the deviation degree between the current waveform in the power grid and the ideal sine waveform, and the number of current harmonic distortions in the power grid can be measured using a power quality analyzer. The electromagnetic interference coefficient of the energy storage system reflects the intensity of electromagnetic interference generated during the operation of the energy storage system. The power of the electromagnetic interference signal generated by the energy storage system can be measured by an electromagnetic interference test receiver, and the ratio of the power of the electromagnetic interference signal to the set reference signal power is used as the electromagnetic interference coefficient of the energy storage system. The average charge-discharge efficiency of the energy storage system reflects the average energy conversion efficiency during the charge-discharge operation of the energy storage system within a preset monitoring period. The charge-discharge efficiency of the energy storage system at multiple moments within the preset monitoring period can be measured by a data acquisition system, and the average value is taken to obtain the average charge-discharge efficiency of the energy storage system.

[0049] Based on the processing of the grid connection characteristic parameters of the energy storage system, the grid connection eigenvalue of the energy storage system is obtained, and the grid connection eigenvalue of the energy storage system is used to quantify the stability degree of the process of the energy storage system accessing the power grid.

[0050] In this embodiment, the grid connection eigenvalue of the energy storage system can be obtained through the following analysis method, and the specific analysis conditions are as follows:

[0051] ;

[0052] In the formula, represents the grid connection eigenvalue of the energy storage system, represents the frequency fluctuation coefficient of the power grid, represents the grid connection characteristic correction factor corresponding to the set frequency fluctuation coefficient, represents the number of current harmonic distortions in the power grid, represents the set defined number of current harmonic distortions, represents the grid connection characteristic correction factor corresponding to the set number of current harmonic distortions, represents the electromagnetic interference coefficient of the energy storage system, represents the grid connection characteristic correction factor corresponding to the set electromagnetic interference coefficient, represents the average charge-discharge efficiency of the energy storage system, represents the grid connection characteristic correction factor corresponding to the set unit charge-discharge efficiency, and e represents the natural constant.

[0053] It should be added that in this embodiment, the grid connection characteristic correction factors corresponding to the preset frequency fluctuation coefficient, the current harmonic distortion times, the electromagnetic interference coefficient, and the unit charge-discharge efficiency are obtained from the impedance scan test database.

[0054] It should be explained that the grid connection characteristic correction factors corresponding to the frequency fluctuation coefficient, the current harmonic distortion times, the electromagnetic interference coefficient, and the unit charge-discharge efficiency are respectively used to adjust the importance of the frequency fluctuation coefficient of the power grid, the current harmonic distortion times of the power grid, the electromagnetic interference coefficient of the energy storage system, and the average charge-discharge efficiency of the energy storage system in the process of analyzing the grid connection characteristic values of the energy storage system. For example, there is a preset mapping relationship between the grid connection characteristic parameters of the energy storage system and the corresponding grid connection characteristic correction factors in the impedance scan test database. Through the preset mapping relationship, the grid connection characteristic correction factors corresponding to the real-time grid connection characteristic parameters of the energy storage system can be matched. The frequency fluctuation coefficient of the power grid, the current harmonic distortion times of the power grid, the electromagnetic interference coefficient of the energy storage system, and the average charge-discharge efficiency of the energy storage system are respectively matched with the preset mapping relationship to obtain the grid connection characteristic correction factors corresponding to the frequency fluctuation coefficient, the current harmonic distortion times, the electromagnetic interference coefficient, and the unit charge-discharge efficiency.

[0055] In this implementation scheme, there is a correlation among the frequency fluctuation coefficient of the power grid, the current harmonic distortion times of the power grid, the electromagnetic interference coefficient of the energy storage system, and the average charge-discharge efficiency of the energy storage system, and they do not exist independently. For example, frequency fluctuations will affect the operating state of the power grid. An increase in the frequency fluctuation coefficient may be accompanied by an increase in the current harmonic distortion times. The power grid frequency fluctuation may affect the working mode of the energy storage system. In the case of a large frequency fluctuation coefficient, the energy storage system may be adjusted frequently to maintain the stability of the power grid, which will exacerbate the electromagnetic interference in the energy storage system and lead to an increase in the electromagnetic interference coefficient of the energy storage system. An excessively high electromagnetic interference coefficient may cause an increase in equipment losses, thereby reducing the charge-discharge efficiency of the system. The low charge-discharge efficiency of the energy storage system may increase the generation of current harmonics and increase the current harmonic distortion times. By comprehensively analyzing the grid connection characteristic values of the energy storage system, the adjustment ability of the energy storage system to connect to the grid can be improved.

[0056] The output power adjustment value of the power electronic grid-connected converter is matched according to the grid connection characteristic values of the energy storage system. The current output power of the power electronic grid-connected converter is added to the output power adjustment value of the power electronic grid-connected converter to obtain the output power target execution value of the power electronic grid-connected converter. The power electronic grid-connected converter is modulated for grid connection according to the output power target execution value of the power electronic grid-connected converter.

[0057] It should be noted that the output power adjustment value of the power electronic grid-connected converter is obtained by matching the grid-connected eigenvalue of the energy storage system. The specific process is to match the grid-connected eigenvalue of the energy storage system with the output power adjustment value of the power electronic grid-connected converter corresponding to each grid-connected eigenvalue interval stored in the impedance scanning test database, and count the output power adjustment value of the power electronic grid-connected converter corresponding to the interval where the grid-connected eigenvalue of the energy storage system is located, which is recorded as the output power adjustment value of the power electronic grid-connected converter.

[0058] It should be explained that the analysis of the grid-connected characteristic parameters of the energy storage system can reflect the stability of the energy storage system during the process of connecting to the grid. If the stability of the energy storage system during the process of connecting to the grid is poor and the subsequent connection is carried out with the output power of the original default power electronic grid-connected converter, it may affect the normal operation of the grid and the performance of electrical equipment. Therefore, it is necessary to modulate the power electronic grid-connected converter in combination with the grid-connected eigenvalue of the energy storage system. The larger the grid-connected eigenvalue of the energy storage system, the better the stability of the energy storage system during the process of connecting to the grid, and the smaller the output power adjustment value of the power electronic grid-connected converter obtained by matching. The output power target execution value of the power electronic grid-connected converter refers to the adjustment target value of the output power of the power electronic grid-connected converter.

[0059] Specifically, the fluctuation detection of the modulated grid-connected energy storage system is carried out. The specific process is as follows: the fluctuation detection data of the grid-connected energy storage system is obtained by performing fluctuation detection on the modulated grid-connected energy storage system. The fluctuation detection data of the grid-connected energy storage system includes the voltage fluctuation coefficient, frequency fluctuation coefficient, phase shift coefficient, and current peak value of the grid-connected energy storage system within a preset fluctuation monitoring period.

[0060] It should be noted that the voltage fluctuation coefficient of the grid-connected energy storage system reflects the degree of voltage fluctuation in the grid-connected energy storage system. The voltage of the grid-connected energy storage system at multiple moments within a preset fluctuation monitoring period can be measured using a voltage sensor, and then the ratio of the standard deviation to the average value of the voltage of the grid-connected energy storage system is used as the voltage fluctuation coefficient of the grid-connected energy storage system. The frequency fluctuation coefficient of the grid-connected energy storage system reflects the impact of the grid-connected energy storage system on the grid frequency stability during the charge and discharge process. The frequency of the grid-connected energy storage system at multiple moments within a preset fluctuation monitoring period can be measured using a power quality analyzer, and then the standard deviation and average value of the frequency of the grid-connected energy storage system within the preset fluctuation monitoring period are obtained. The ratio of the standard deviation to the average value of the frequency of the grid-connected energy storage system within the preset fluctuation monitoring period is used as the frequency fluctuation coefficient of the grid-connected energy storage system. The phase shift coefficient of the grid-connected energy storage system reflects the degree of change in the current phase during the grid connection process of the energy storage system. The phase angles of the output current of the energy storage system and the grid current can be measured through a phase meter, and the absolute value of the difference between the phase angle of the output current of the energy storage system and the phase angle of the grid current after removing the unit is used as the phase shift coefficient of the grid-connected energy storage system. The current peak value of the grid-connected energy storage system reflects the maximum current value generated during the grid connection process of the energy storage system. The current waveform of the grid-connected energy storage system within a preset fluctuation monitoring period can be measured using a current sensor, and the current value at the peak point of the current waveform is found as the current peak value.

[0061] Comprehensive analysis of the fluctuation detection data of the grid-connected energy storage system yields the fluctuation detection evaluation value of the grid-connected energy storage system, which is used to comprehensively quantify the degree of fluctuation of the grid-connected energy storage system.

[0062] In this embodiment, the fluctuation detection evaluation value of the grid-connected energy storage system can be obtained through the following analysis method, and the specific analysis conditions are as follows:

[0063] ;

[0064] In the formula, represents the fluctuation detection evaluation value of the grid-connected energy storage system, represents the voltage fluctuation coefficient of the grid-connected energy storage system, represents the fluctuation detection evaluation factor corresponding to the set voltage fluctuation coefficient, represents the frequency fluctuation coefficient of the grid-connected energy storage system, represents the fluctuation detection evaluation factor corresponding to the set frequency fluctuation coefficient, represents the phase shift coefficient of the grid-connected energy storage system, represents the fluctuation detection evaluation factor corresponding to the set phase shift coefficient, represents the current peak value of the grid-connected energy storage system, represents the set reference current peak value, Indicates the fluctuation detection evaluation factor corresponding to the set unit current.

[0065] It should be noted that using the hyperbolic tangent function to compress the input voltage fluctuation coefficient helps to avoid extreme situations where the input is too large or too small. The exponential function helps to highlight the importance of larger values ​​of the frequency fluctuation coefficient. The inverse hyperbolic cosine operation is performed on the addition result of the voltage fluctuation coefficient and the frequency fluctuation coefficient after nonlinear processing, which can be used to compress the value range and convert the input value into a smoother result. Through this function nesting method, the fluctuation detection evaluation value can be gradually affected, and each factor can be processed according to importance and complexity to avoid excessive influence of a single factor, thereby achieving accurate evaluation of the fluctuation of the grid-connected energy storage system.

[0066] It should be added that, in this embodiment, the fluctuation detection evaluation factor corresponding to the preset voltage fluctuation coefficient, the fluctuation detection evaluation factor corresponding to the frequency fluctuation coefficient, the fluctuation detection evaluation factor corresponding to the phase shift coefficient and the fluctuation detection evaluation factor corresponding to the unit current are obtained from the impedance scanning test database.

[0067] It needs to be explained that the voltage fluctuation coefficient, frequency fluctuation coefficient, phase shift coefficient and fluctuation detection evaluation factor corresponding to the unit current are respectively used to adjust the importance of the voltage fluctuation coefficient, frequency fluctuation coefficient, phase shift coefficient and current peak value of the grid-connected energy storage system in the process of analyzing and obtaining the fluctuation detection evaluation value of the grid-connected energy storage system. For example, there is a pre-set mapping relationship between the fluctuation detection data of the grid-connected energy storage system and the corresponding fluctuation detection evaluation factor in the impedance scanning test database. The fluctuation detection evaluation factor corresponding to the real-time fluctuation detection data of the grid-connected energy storage system can be matched through the pre-set mapping relationship. The voltage fluctuation coefficient, frequency fluctuation coefficient, phase shift coefficient and current peak value of the grid-connected energy storage system are matched with the pre-set mapping relationship respectively to obtain the voltage fluctuation coefficient, frequency fluctuation coefficient, phase shift coefficient and fluctuation detection evaluation factor corresponding to the unit current.

[0068] In this implementation scheme, the voltage fluctuation coefficient, frequency fluctuation coefficient, phase shift coefficient and current peak of the grid-connected energy storage system are correlated and do not exist independently. For example, the voltage fluctuation coefficient will be affected by the phase difference between the energy storage system and the power grid. If the phase shift coefficient is large, it may cause more severe voltage fluctuations and increase the voltage fluctuation coefficient, affecting the stability of the power grid. Frequency fluctuations usually reflect the instability of the power grid load, and the appearance of current peaks may aggravate frequency fluctuations. The increase in current peaks may affect voltage fluctuations. Comprehensive analysis can be used to obtain the fluctuation detection evaluation value of the grid-connected energy storage system, which can understand the impact of the energy storage system on the stability of the power grid, and provide data support for the improvement of the grid-connected energy storage system.

[0069] Specifically, the grid fluctuation results of the grid-connected energy storage system are analyzed, and the specific process is as follows: The grid fluctuation results of the grid-connected energy storage system include abnormal grid fluctuations and normal grid fluctuations.

[0070] Extract the fluctuation detection evaluation threshold of the grid-connected energy storage system stored in the impedance scan test database, compare the fluctuation detection evaluation value of the grid-connected energy storage system with the fluctuation detection evaluation threshold of the grid-connected energy storage system. If the fluctuation detection evaluation value of the grid-connected energy storage system is higher than the fluctuation detection evaluation threshold of the grid-connected energy storage system, mark the grid fluctuation result of the grid-connected energy storage system as abnormal grid fluctuation; otherwise, mark the grid fluctuation result of the grid-connected energy storage system as normal grid fluctuation.

[0071] Specifically, the grid-connected energy storage system is configured according to the grid fluctuation results of the grid-connected energy storage system, and the specific process is as follows: Extract the grid fluctuation results of the grid-connected energy storage system. If the grid fluctuation result of the grid-connected energy storage system is normal grid fluctuation, continue to configure the grid-connected energy storage system with the current phase-locked loop integral gain of the grid-connected energy storage system.

[0072] If the grid fluctuation result of the grid-connected energy storage system is abnormal grid fluctuation, add the current phase-locked loop integral gain of the grid-connected energy storage system to the set phase-locked loop integral gain increment value of the grid-connected energy storage system to obtain the target achievement value of the phase-locked loop integral gain of the grid-connected energy storage system, and adjust the current phase-locked loop integral gain of the grid-connected energy storage system up to the target achievement value of the phase-locked loop integral gain of the grid-connected energy storage system for configuration.

[0073] It should be noted that the phase-locked loop integral gain is used to reduce the steady-state error and improve the phase accuracy of the phase-locked loop. By increasing the phase-locked loop integral gain of the grid-connected energy storage system, the grid frequency and phase can be better tracked, the system instability caused by grid fluctuations can be reduced, and at the same time, the response speed of the system to grid fluctuations can be improved.

[0074] It should be noted that in this embodiment, after the grid-connected energy storage system is configured, the fluctuation detection data of the grid-connected energy storage system will be continuously analyzed, and then continuously configured until the grid fluctuation result of the analyzed grid-connected energy storage system is normal grid fluctuation.

[0075] Specifically, the impedance scan test execution parameters are processed and the impedance scan test start signal is sent at the same time. The specific process is as follows: Extract the grid fluctuation results of the grid-connected energy storage system. If the grid fluctuation result of the grid-connected energy storage system is normal grid fluctuation, set the impedance scan test standard parameters as the impedance scan test execution parameters.

[0076] If the grid fluctuation result of the grid-connected energy storage system is abnormal grid fluctuation, then the difference between the fluctuation detection and evaluation value of the grid-connected energy storage system and the fluctuation detection and evaluation threshold of the grid-connected energy storage system is recorded as the impedance scan test comparison value, and the impedance scan test execution parameters are obtained by matching according to the impedance scan test comparison value.

[0077] It should be noted that the process of obtaining the impedance scan test execution parameters by matching according to the impedance scan test comparison value is as follows: the impedance scan test comparison value is matched with the impedance scan test execution parameters corresponding to each impedance scan test comparison value interval stored in the impedance scan test database, and the impedance scan test execution parameters corresponding to the interval where the impedance scan test comparison value is located are statistically recorded as the impedance scan test execution parameters.

[0078] It should be explained that the analysis of the fluctuation detection data of the grid-connected energy storage system can reflect the fluctuation degree of the grid-connected energy storage system. If the subsequent test is carried out with the original default impedance scan test execution parameters when the fluctuation of the grid-connected energy storage system is large, it may lead to inaccurate impedance scan test results. Therefore, it is necessary to modulate the impedance scan test execution parameters in combination with the fluctuation detection and evaluation value of the grid-connected energy storage system. The larger the impedance scan test comparison value, the worse the stability of the grid-connected energy storage system. It is necessary to reduce the scan frequency to avoid introducing more interference when the system fluctuates greatly, reduce the amplitude of the injected signal to prevent excessive impact on the system, and at the same time increase the sampling frequency to more accurately capture the dynamic changes of the system. Therefore, the smaller the scan frequency and the amplitude of the injected signal of the impedance scan test obtained by matching, and the larger the sampling frequency.

[0079] The impedance scan test execution parameters include the scan frequency of the impedance scan test, the amplitude of the injected signal of the impedance scan test, and the sampling frequency of the impedance scan test.

[0080] It should be added that adjusting the scan frequency of the impedance scan test can improve the accuracy of the test results, optimize the test time, and reduce the possibility of resonance points. Adjusting the amplitude of the injected signal of the impedance scan test can prevent system overload, protect equipment and improve safety. Different test stages may require different signal amplitudes, and adjusting the amplitude of the injected signal can better meet the test requirements. Adjusting the sampling frequency of the impedance scan test can increase the resolution of the data, better capture the signal changes, improve the adaptability of the test, and make the test results more accurate.

[0081] It should be explained that the scan frequency of the impedance scan test refers to the frequency of the test signal injected into the system when performing the impedance scan test, and the sampling frequency of the impedance scan test refers to the frequency used to collect the system response signal when performing the impedance scan test.

[0082] Specifically, an impedance scan test is performed on the configured grid-connected energy storage system in combination with the impedance scan test execution parameters. The specific process is as follows: The central controller adjusts the impedance scan test parameters of the energy storage system impedance scan test device to the impedance scan test execution parameters, and performs an impedance scan test on the configured grid-connected energy storage system through the energy storage system impedance scan test device to obtain the grid-connected energy storage system impedance scan test parameters. The grid-connected energy storage system impedance scan test parameters include the actual injection signal amplitude of the impedance scan test within the preset scan monitoring period, the environmental deviation coefficient of the impedance scan test, the impedance amplitude fluctuation coefficient of the grid-connected energy storage system, and the voltage fluctuation coefficient of the grid-connected energy storage system.

[0083] It should be noted that the actual injection signal amplitude of the impedance scan test reflects the signal amplitude applied to the system during the test, and the actual injection signal amplitude of the impedance scan test can be measured using a signal generator. The environmental deviation coefficient of the impedance scan test reflects the degree of influence of environmental factors (such as temperature, humidity, and pressure) on the test results during the impedance scan test. The environmental parameters (such as temperature, humidity, and pressure) are measured using environmental monitoring equipment (such as a thermometer, a hygrometer, and a pressure gauge), and the absolute value of the difference between the measured environmental parameters and the set environmental parameter standard values is processed to remove the unit to obtain the environmental parameter deviation value. The value obtained by averaging the environmental parameter deviation values is used as the environmental deviation coefficient of the impedance scan test. For example, according to the temperature and the set temperature standard value, the temperature deviation value is obtained, and according to the humidity and the set humidity standard value, the humidity deviation value is obtained. The temperature deviation value and the humidity standard value are summed and then averaged to obtain the environmental deviation coefficient of the impedance scan test. The impedance amplitude fluctuation coefficient of the grid-connected energy storage system reflects the fluctuation of the impedance amplitude of the energy storage system during grid connection. The impedance amplitude of the grid-connected energy storage system at multiple moments within the preset scan monitoring period is measured using an impedance analyzer, and then the standard deviation and the average value of the impedance amplitude are obtained. The ratio of the standard deviation and the average value of the impedance amplitude is used as the impedance amplitude fluctuation coefficient of the grid-connected energy storage system. The voltage fluctuation coefficient of the grid-connected energy storage system reflects the degree of voltage fluctuation in the grid-connected energy storage system. The voltage of the grid-connected energy storage system at multiple moments within the preset scan monitoring period can be measured using a voltage sensor, and then the ratio of the standard deviation and the average value of the grid-connected energy storage system voltage is used as the voltage fluctuation coefficient of the grid-connected energy storage system.

[0084] Based on the grid-connected energy storage system impedance scan test parameters, the damping characteristic analysis index value of the grid-connected energy storage system is obtained. The damping characteristic analysis index value of the grid-connected energy storage system is used to quantify the ability of the grid-connected energy storage system to suppress grid oscillations.

[0085] In this embodiment, the damping characteristic analysis index value of the grid-connected energy storage system can be obtained through the following analysis method. The specific analysis conditions are as follows:

[0086] ;

[0087] In the formula, represents the damping characteristic analysis index value of the grid-connected energy storage system, represents the actual injection signal amplitude of the impedance scan test, represents the injection signal amplitude of the impedance scan test, represents the damping characteristic analysis weight factor corresponding to the set injection signal amplitude, represents the environmental deviation coefficient of the impedance scan test, represents the damping characteristic analysis weight factor corresponding to the set environmental deviation coefficient, represents the impedance amplitude fluctuation coefficient of the grid-connected energy storage system, represents the damping characteristic analysis weight factor corresponding to the set impedance amplitude fluctuation coefficient, represents the voltage fluctuation coefficient of the grid-connected energy storage system, represents the damping characteristic analysis weight factor corresponding to the set voltage fluctuation coefficient, and e represents the natural constant.

[0088] It should be added that in this embodiment, the damping characteristic analysis weight factor corresponding to the preset injection signal amplitude, the damping characteristic analysis weight factor corresponding to the environmental deviation coefficient, the damping characteristic analysis weight factor corresponding to the impedance amplitude fluctuation coefficient, and the damping characteristic analysis weight factor corresponding to the voltage fluctuation coefficient are obtained from the impedance scan test database.

[0089] It should be explained that the damping characteristic analysis weight factors corresponding to the injection signal amplitude, the environmental deviation coefficient, the impedance amplitude fluctuation coefficient, and the voltage fluctuation coefficient are respectively used to adjust the importance of the actual injection signal amplitude of the impedance scan test, the environmental deviation coefficient of the impedance scan test, the impedance amplitude fluctuation coefficient of the grid-connected energy storage system, and the voltage fluctuation coefficient of the grid-connected energy storage system in the process of analyzing the damping characteristic analysis index value of the grid-connected energy storage system. For example, there is a preset mapping relationship between the impedance scan test parameters of the grid-connected energy storage system and the corresponding damping characteristic analysis weight factors in the impedance scan test database. Through the preset mapping relationship, the damping characteristic analysis weight factor corresponding to the real-time impedance scan test parameters of the grid-connected energy storage system can be matched. The actual injection signal amplitude of the impedance scan test, the environmental deviation coefficient of the impedance scan test, the impedance amplitude fluctuation coefficient of the grid-connected energy storage system, and the voltage fluctuation coefficient of the grid-connected energy storage system are respectively matched with the preset mapping relationship to obtain the damping characteristic analysis weight factors corresponding to the injection signal amplitude, the environmental deviation coefficient, the impedance amplitude fluctuation coefficient, and the voltage fluctuation coefficient.

[0090] In this implementation, there is a correlation among the actual injection signal amplitude of the impedance scanning test, the environmental deviation coefficient of the impedance scanning test, the impedance amplitude fluctuation coefficient of the grid-connected energy storage system, and the voltage fluctuation coefficient of the grid-connected energy storage system, and they do not exist independently. For example, due to the change in amplitude, it may lead to measurement errors, so the actual injection signal amplitude will affect the impedance value obtained during the test. The environmental deviation coefficient may cause voltage fluctuations in the grid-connected energy storage system, thereby affecting the voltage fluctuation coefficient of the grid-connected energy storage system. The change in environmental factors may trigger fluctuations in the impedance amplitude of the grid-connected energy storage system, thereby affecting the voltage fluctuations of the energy storage system. By comprehensively analyzing the damping characteristic analysis index value of the grid-connected energy storage system, the stability of the system under different conditions can be evaluated more accurately, providing data support for the design optimization of the grid-connected energy storage system.

[0091] Specifically, to obtain the damping characteristic information of the grid-connected energy storage system, the specific process is as follows: Import the damping characteristic analysis index value of the grid-connected energy storage system into the damping characteristic analysis model to obtain the damping characteristic information of the grid-connected energy storage system.

[0092] It should be noted that the mathematical formula of the damping characteristic analysis model is:

[0093] ;

[0094] In the formula, represents the damping characteristic information of the grid-connected energy storage system, represents normal damping characteristics, represents abnormal damping characteristics, represents damping characteristic failure, represents the damping characteristic analysis index value of the grid-connected energy storage system, represents the first threshold of damping characteristic analysis, represents the second threshold of damping characteristic analysis.

[0095] Mark the damping characteristic analysis index value of the grid-connected energy storage system as .

[0096] Statistically analyze the first threshold of damping characteristic analysis and the second threshold of damping characteristic analysis in the damping characteristic analysis model, and mark them as 、 .

[0097] After being processed by the damping characteristic analysis model, if , then mark the damping characteristic information of the grid-connected energy storage system as normal damping characteristics.

[0098] If , then mark the damping characteristic information of the grid-connected energy storage system as abnormal damping characteristics.

[0099] If , the damping characteristic information of the grid-connected energy storage system is marked as a damping characteristic fault.

[0100] Specifically, for the power stability control of the grid-connected energy storage system, the specific process is as follows: extract the damping characteristic information of the grid-connected energy storage system. If the damping characteristic information of the grid-connected energy storage system is normal for damping characteristics, continue the power stability control with the current operating mode of the grid-connected energy storage system. If the damping characteristic information of the grid-connected energy storage system is abnormal for damping characteristics, adjust the current operating mode of the grid-connected energy storage system to the frequency modulation mode. If the damping characteristic information of the grid-connected energy storage system is a damping characteristic fault, adjust the current operating mode of the grid-connected energy storage system to the frequency modulation and voltage regulation mode.

[0101] It should be explained that the frequency modulation mode is to control the frequency of the power grid within a preset frequency range, which can maintain the frequency stability of the grid-connected energy storage system and ensure the reliable operation of the power system. The frequency modulation and voltage regulation mode is to control both the frequency and voltage of the power grid within a preset range, which can guarantee the dual stability of the power system. When the damping characteristic information is abnormal for damping characteristics, it indicates that the damping ability of the system has decreased, and it may not be able to effectively suppress the frequency fluctuations of the power grid. Adjusting the operating mode to the frequency modulation mode can focus on improving the frequency response ability of the system, compensating for the frequency fluctuations by adjusting the active power, thereby improving the damping effect and ensuring the stability of the power grid frequency. When the damping characteristic information is a damping characteristic fault, it means that the damping ability of the system is seriously insufficient, and it can neither effectively suppress the frequency fluctuations nor ensure the voltage stability. It is necessary to adjust both the active and reactive powers simultaneously to cope with the complex fluctuations of the power grid, and then more effectively cope with the frequency and voltage fluctuations of the power grid to ensure the stable operation of the power grid.

[0102] It should be noted that the impedance scanning test method for the energy storage system based on grid connection characteristics also includes an impedance scanning test database for storing the first parameter set, the second parameter set, and the third parameter set obtained by analyzing historical data.

[0103] The first parameter set includes the defined current harmonic distortion times, the grid connection characteristic correction factors corresponding to the frequency fluctuation coefficient, the grid connection characteristic correction factors corresponding to the current harmonic distortion times, the grid connection characteristic correction factors corresponding to the electromagnetic interference coefficient, the grid connection characteristic correction factors corresponding to the unit charge and discharge efficiency, and the output power adjustment values of the power electronic grid connection converter corresponding to the grid connection characteristic value intervals of each energy storage system.

[0104] The second parameter set includes the reference current peak value, the fluctuation detection and evaluation factor corresponding to the voltage fluctuation coefficient, the fluctuation detection and evaluation factor corresponding to the frequency fluctuation coefficient, the fluctuation detection and evaluation factor corresponding to the phase shift coefficient, the fluctuation detection and evaluation factor corresponding to the unit current, the fluctuation detection and evaluation threshold of the grid-connected energy storage system, the PLL integral gain supplement value of the grid-connected energy storage system, and the impedance scanning test execution parameters corresponding to each impedance scanning test comparison value interval.

[0105] The third parameter set includes the damping characteristic analysis weight factor corresponding to the injection signal amplitude, the damping characteristic analysis weight factor corresponding to the environmental deviation coefficient, the damping characteristic analysis weight factor corresponding to the impedance amplitude fluctuation coefficient, and the damping characteristic analysis weight factor corresponding to the voltage fluctuation coefficient.

[0106] The second aspect of the present invention provides an apparatus for the impedance scanning test method of an energy storage system based on grid connection characteristics, further including: a processor, and a memory and a network interface connected to the processor: the network interface is connected to the non-volatile memory in the server: when running, the processor retrieves a computer program from the non-volatile memory through the network interface, and runs the computer program through the memory to execute the above-mentioned impedance scanning test method of the energy storage system based on grid connection characteristics.

[0107] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0108] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art in the relevant technical field can well understand and utilize the present invention.

Claims

1. An impedance scanning test method for an energy storage system based on grid-connected characteristics, characterized in that: include: The energy storage system is connected to the grid through a power electronic grid-connected converter. By continuously analyzing the connection process, the grid-connected characteristic parameters of the energy storage system are obtained, and then the power electronic grid-connected converter is modulated for grid connection. Perform fluctuation detection on the modulated grid-connected energy storage system, and then analyze and obtain the grid fluctuation result of the grid-connected energy storage system, configure the grid-connected energy storage system according to the grid fluctuation result of the grid-connected energy storage system, and process to obtain the impedance scanning test execution parameters, and send the impedance scanning test start signal at the same time; The central controller receives the impedance scanning test start signal, performs an impedance scanning test on the configured grid-connected energy storage system in combination with the impedance scanning test execution parameters, obtains the damping characteristic information of the grid-connected energy storage system, and sends the damping characteristic information of the grid-connected energy storage system to the central control platform; The central control platform receives the damping characteristic information of the grid-connected energy storage system, performs power stability control on the grid-connected energy storage system, and sends the control results to the mobile terminal for display.

2. The energy storage system impedance scanning test method based on grid-connected characteristics according to claim 1 is characterized in that: The specific process of performing grid-connected modulation on the power electronic grid-connected converter is as follows: The grid-connected characteristic parameters of the energy storage system include the frequency fluctuation coefficient of the power grid within a preset monitoring period, the number of current harmonic distortions of the power grid, the electromagnetic interference coefficient of the energy storage system, and the average charge and discharge efficiency of the energy storage system; Based on the energy storage system grid-connected characteristic parameters, the energy storage system grid-connected characteristic values ​​are obtained, and the energy storage system grid-connected characteristic values ​​are used to quantify the stability of the energy storage system in the process of connecting to the power grid; The output power adjustment value of the power electronic grid-connected converter is obtained by matching the grid-connected characteristic value of the energy storage system, the output power of the current power electronic grid-connected converter is added to the output power adjustment value of the power electronic grid-connected converter to obtain the output power target execution value of the power electronic grid-connected converter, and the power electronic grid-connected converter is grid-connected modulated according to the output power target execution value of the power electronic grid-connected converter.

3. The impedance scanning test method for energy storage system based on grid-connected characteristics according to claim 1 is characterized in that: The specific process of performing fluctuation detection on the modulated grid-connected energy storage system is as follows: Performing fluctuation detection on the modulated grid-connected energy storage system to obtain fluctuation detection data of the grid-connected energy storage system, wherein the fluctuation detection data of the grid-connected energy storage system includes a voltage fluctuation coefficient, a frequency fluctuation coefficient, a phase shift coefficient and a current peak value of the grid-connected energy storage system within a preset fluctuation monitoring period; A comprehensive analysis is performed on the fluctuation detection data of the grid-connected energy storage system to obtain a fluctuation detection evaluation value of the grid-connected energy storage system, and the fluctuation detection evaluation value of the grid-connected energy storage system is used to comprehensively quantify the fluctuation degree of the grid-connected energy storage system.

4. The impedance scanning test method for energy storage system based on grid-connected characteristics according to claim 3 is characterized in that: The analysis obtains the grid fluctuation results of the grid-connected energy storage system. The specific process is as follows: The grid fluctuation results of the grid-connected energy storage system include abnormal grid fluctuation and normal grid fluctuation; The fluctuation detection assessment threshold of the grid-connected energy storage system stored in the impedance scanning test database is extracted, and the fluctuation detection assessment value of the grid-connected energy storage system is compared with the fluctuation detection assessment threshold of the grid-connected energy storage system. If the fluctuation detection assessment value of the grid-connected energy storage system is higher than the fluctuation detection assessment threshold of the grid-connected energy storage system, the grid fluctuation result of the grid-connected energy storage system is marked as abnormal grid fluctuation; otherwise, the grid fluctuation result of the grid-connected energy storage system is marked as normal grid fluctuation.

5. The impedance scanning test method for energy storage system based on grid-connected characteristics according to claim 4 is characterized in that: The specific process of configuring the grid-connected energy storage system according to the grid fluctuation result of the grid-connected energy storage system is as follows: Extract the grid fluctuation result of the grid-connected energy storage system. If the grid fluctuation result of the grid-connected energy storage system is that the grid fluctuation is normal, continue to configure the grid-connected energy storage system with the current phase-locked loop integral gain of the grid-connected energy storage system. If the grid fluctuation result of the grid-connected energy storage system is abnormal grid fluctuation, the current phase-locked loop integral gain of the grid-connected energy storage system is added to the set phase-locked loop integral gain supplement value of the grid-connected energy storage system to obtain the phase-locked loop integral gain target achievement value of the grid-connected energy storage system, and the current phase-locked loop integral gain of the grid-connected energy storage system is increased to the phase-locked loop integral gain target achievement value of the grid-connected energy storage system for configuration.

6. The impedance scanning test method for energy storage system based on grid-connected characteristics according to claim 5 is characterized in that: The processing obtains the impedance scanning test execution parameters and sends the impedance scanning test start signal at the same time. The specific process is as follows: Extracting the grid fluctuation result of the grid-connected energy storage system, if the grid fluctuation result of the grid-connected energy storage system is that the grid fluctuation is normal, setting the impedance scanning test standard parameter as the impedance scanning test execution parameter; If the grid fluctuation result of the grid-connected energy storage system is abnormal grid fluctuation, the difference between the fluctuation detection evaluation value of the grid-connected energy storage system and the fluctuation detection evaluation threshold of the grid-connected energy storage system is recorded as the impedance scanning test control value, and the impedance scanning test execution parameters are obtained according to the impedance scanning test control value matching; The impedance scanning test execution parameters include the scanning frequency of the impedance scanning test, the injection signal amplitude of the impedance scanning test and the sampling frequency of the impedance scanning test.

7. The impedance scanning test method for energy storage system based on grid-connected characteristics according to claim 6 is characterized in that: The impedance scanning test is performed on the configured grid-connected energy storage system in combination with the impedance scanning test execution parameters. The specific process is as follows: The central controller adjusts the impedance scanning test parameters of the energy storage system impedance scanning test device to the impedance scanning test execution parameters, and performs an impedance scanning test on the configured grid-connected energy storage system through the energy storage system impedance scanning test device to obtain the impedance scanning test parameters of the grid-connected energy storage system, wherein the impedance scanning test parameters of the grid-connected energy storage system include the actual injection signal amplitude of the impedance scanning test within a preset scanning monitoring period, the environmental deviation coefficient of the impedance scanning test, the impedance amplitude fluctuation coefficient of the grid-connected energy storage system, and the voltage fluctuation coefficient of the grid-connected energy storage system; Based on the impedance scanning test parameter processing of the grid-connected energy storage system, a damping characteristic analysis index value of the grid-connected energy storage system is obtained, and the damping characteristic analysis index value of the grid-connected energy storage system is used to quantify the ability of the grid-connected energy storage system to suppress grid oscillation.

8. The method for impedance scanning test of energy storage system based on grid-connected characteristics according to claim 7, characterized in that: The specific process of obtaining the damping characteristic information of the grid-connected energy storage system is as follows: Importing the damping characteristic analysis index value of the grid-connected energy storage system into the damping characteristic analysis model to obtain the damping characteristic information of the grid-connected energy storage system; The damping characteristic analysis index value of the grid-connected energy storage system is marked as K; A damping characteristic analysis first threshold and a damping characteristic analysis second threshold in the statistical damping characteristic analysis model are marked as ω1 and ω2 respectively; After being processed by the damping characteristic analysis model, if K ≥ ω1, the damping characteristic information of the grid-connected energy storage system is marked as normal damping characteristics; If ω1>K≥ω2, the damping characteristic information of the grid-connected energy storage system is marked as abnormal damping characteristic; If ω2>K, the damping characteristic information of the grid-connected energy storage system is marked as a damping characteristic fault; The mathematical formula of the damping characteristic analysis model is: Wherein, L represents the damping characteristic information of the grid-connected energy storage system, L1 represents normal damping characteristics, L2 represents abnormal damping characteristics, L3 represents damping characteristic failure, K represents the damping characteristic analysis index value of the grid-connected energy storage system, ω1 represents the first threshold of damping characteristic analysis, and ω2 represents the second threshold of damping characteristic analysis.

9. The method for impedance scanning test of energy storage system based on grid-connected characteristics according to claim 8, characterized in that: The specific process of performing power stability control on the grid-connected energy storage system is as follows: The damping characteristic information of the grid-connected energy storage system is extracted. If the damping characteristic information of the grid-connected energy storage system indicates that the damping characteristic is normal, the power stability control is continued with the current operation mode of the grid-connected energy storage system. If the damping characteristic information of the grid-connected energy storage system indicates that the damping characteristic is abnormal, the current operation mode of the grid-connected energy storage system is adjusted to the frequency regulation mode. If the damping characteristic information of the grid-connected energy storage system indicates that the damping characteristic is faulty, the current operation mode of the grid-connected energy storage system is adjusted to the frequency and voltage regulation mode.

10. An energy storage system impedance scanning test device based on grid-connected characteristics, characterized in that: It includes: a processor, and a memory and a network interface connected to the processor; the network interface is connected to a non-volatile memory in a server; when the processor is running, it calls a computer program from the non-volatile memory through the network interface, and runs the computer program through the memory to execute the method described in any one of claims 1 to 9.

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