Method and device for detecting networking and grid-connected capabilities of networking type energy storage system

Abstract

The invention discloses a method and a device for detecting networking and grid-connected capabilities of a networking type energy storage system, and belongs to the field of power system detection. The method comprises the following steps: disconnecting the energy storage system from an external power grid, testing whether the energy storage system is independently started or not, and establishing a stable voltage; a dynamic power compensation algorithm is adopted to ensure that the voltage and the frequency are kept stable under load fluctuation, and a time domain response analysis method is adopted to ensure that the recovery time is less than or equal to 200ms; the grid-connected power is gradually increased or reduced, and the adjustment and response capability of the system within the rated power range of 0-100% is tested; applying voltage disturbances with different amplitudes, observing the dynamic response of the tested energy storage system, and testing whether the system can operate stably and keep active power output; a main power grid is simulated to be disconnected, whether an energy storage system recognizes and enters an island mode is detected, and the island detection speed is increased by using an improved positive and negative sequence impedance measurement method. A positive and negative sequence impedance measurement algorithm is adopted, the disconnection state of the main power grid is detected more quickly, island detection time is remarkably shortened, and fluctuation of voltage and frequency is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system detection, and more specifically, relates to a method and device for detecting the networking and grid-connection capabilities of a grid-type energy storage system. Background Art

[0002] With the rapid development of renewable energy generation, primarily wind and photovoltaic power, energy storage systems are playing a vital role in improving grid stability, balancing power supply and demand, and enhancing power quality. Energy storage systems not only operate in parallel with the main grid but also provide backup power in the event of a main grid failure or disconnection, maintaining normal power supply to local loads. In this process, islanding detection, black start, and grid-connection control have become key technologies for the safe and stable operation of energy storage systems.

[0003] Islanding refers to a state in which an energy storage system or distributed generation (DG) continues to supply power to localized loads after the main grid is disconnected. Harmful effects of islanding include: When the grid is restored, the energy storage system operating in island mode may lose synchronization with the grid, causing current surges and impacting the safety of grid equipment. Voltage and frequency fluctuations in islanding mode can be significant, leading to abnormal operation or even damage to load equipment. Grid maintenance personnel may mistakenly believe the grid is out when the energy storage system in islanding mode is still providing power, potentially causing electric shock. To improve the accuracy and speed of islanding detection, researchers have proposed new methods, such as those based on positive- and negative-sequence impedance measurement. This method leverages the impedance characteristics of the grid, which reveal significant changes in the system's positive- and negative-sequence impedances during islanding. By measuring and analyzing these impedance changes, islanding can be detected more quickly and accurately. However, existing positive- and negative-sequence impedance detection methods still suffer from insufficient accuracy and long response times, compromising the real-time and reliability of islanding detection. After the main grid is disconnected, grid-connected energy storage systems must quickly switch to islanding mode and maintain voltage and frequency stability for localized loads. Due to the high complexity of the control algorithm of the current grid-type energy storage system, the grid-type energy storage system may not be able to adjust the control parameters in a timely manner, resulting in large fluctuations in the voltage and frequency of the local load. In the island operation mode, the interaction between the grid-type energy storage system and the load may cause oscillation in the energy storage system. The grid-type energy storage is used as a voltage source. If multiple voltage source devices are operated in parallel, there may be problems such as circulating current, power imbalance or control coordination, affecting the stability of the system.

[0004] In view of the problems of the above or existing methods and systems for detecting the networking and grid-connection capabilities of grid-type energy storage systems, the present invention is proposed.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The embodiment of the present invention provides a method for detecting the networking and grid-connected capabilities of a grid-type energy storage system, including: building a test environment, configuring an energy storage system to be tested, disconnecting the energy storage system from the external power grid, testing whether it can start independently and establish a stable voltage, and recording the voltage establishment time, steady-state error, and fluctuation; connecting a nonlinear mixed load group containing variable resistance, inductance, and capacitance, detecting the dynamic response characteristics of the energy storage system to different load changes, using a dynamic power compensation algorithm to ensure that the voltage and frequency remain stable under load fluctuations, applying a sudden load, and detecting the recovery time of the energy storage system under test, which should be ≤ Before switching to grid-connected mode, the energy storage system should adjust its own voltage, frequency, and phase, gradually increasing or decreasing the grid-connected power, testing the system's regulation and response capabilities within the 0-100% rated power range, and optimizing the grid-connected power adjustment process based on an adaptive power allocation algorithm. Voltage disturbances of varying amplitudes should be applied to observe the dynamic response of the energy storage system under test, and a graded voltage compensation algorithm should be used to test whether the system can operate stably and maintain active power output. A main grid disconnection should be simulated to detect whether the energy storage system recognizes and enters islanding mode, and an improved positive and negative sequence impedance measurement method should be used to increase the speed of islanding detection.

[0007] As a preferred solution for testing the networking and grid-connection capabilities of the grid-connecting energy storage system described in the present invention, the following steps are performed: disconnecting the energy storage system from the external grid to test whether it can independently start up and establish a stable grid voltage, and recording the voltage establishment time, steady-state error, and fluctuation. The following steps are performed: triggering the energy storage system's self-starting mechanism to observe whether the converter starts normally and recording the converter's self-test time during the startup process; starting the converter and entering the grid-connecting mode to begin outputting voltage, recording the time series from control enable to voltage stabilization, collecting the output voltage waveform, and analyzing the rise rate and overshoot; and using FFT spectrum analysis to analyze the harmonic content of the voltage waveform, calculate the total harmonic distortion rate, and observe whether the voltage has low-frequency oscillations or high-frequency spikes.

[0008] As a preferred embodiment of the method for detecting the grid-connection and grid-connection capabilities of the grid-connected energy storage system described in the present invention, a nonlinear mixed load group containing variable resistance, inductance, and capacitance is connected to detect the dynamic response characteristics of the energy storage system to different load changes. A dynamic power compensation algorithm is used to ensure that the voltage and frequency remain stable under load fluctuations. The method includes: recording the voltage, frequency, and total harmonic distortion of the energy storage unit (system) in the no-load state, gradually increasing the load from 10% to 50% to 100% of the rated power, and measuring the voltage drop amplitude, frequency deviation, and recovery time T. rec ; Connect the transformer and inductive load, gradually increase the inductive load power, record the current lag angle θ and the voltage drop amplitude, and observe the frequency fluctuation; connect the high-power capacitor bank, gradually adjust the capacitive load power, record the current lead angle θ and voltage fluctuation, and optimize the voltage stability by adjusting the reactive output of the converter.

[0009] As a preferred solution of the method for detecting the grid-connection and grid-connection capabilities of the grid-connected energy storage system of the present invention, wherein: applying a sudden load and detecting the recovery time of the energy storage system, using a time domain response analysis method, the recovery time should be ≤ 200ms, including:

[0010] Calculate the voltage recovery time and the voltage change model calculation formula as follows:

[0011] Where V(t) is the instantaneous voltage, V set is the set voltage, ΔV is the voltage deviation, τ is the time constant, t is the time variable, is an exponential decay term;

[0012] The frequency change calculation formula is as follows:

[0013]

[0014] Where f(t) is the instantaneous frequency, f set is the set frequency, Δf is the frequency deviation, τ is the frequency recovery time constant, t is the time variable, is an exponential decay term;

[0015] The voltage and frequency change data are extracted by a high-speed oscilloscope to calculate the voltage recovery time T rec and frequency recovery time T f-rec , MATLAB is used to fit the data, and then the time constants τ and τ are fitted by the least squares method. f , and then determine the recovery time, set T re and T f-rec The measured values ​​are X and Y. If X, Y ≤ 200ms, the test passes; otherwise, the compensation strategy is adjusted.

[0016] As a preferred embodiment of the method for testing the grid-connected and grid-connected capabilities of the grid-connected energy storage system of the present invention, the method includes gradually increasing or decreasing the grid-connected power to test the system's regulation and response capabilities within a range of 0-100% of the rated power, and optimizing the grid-connected power adjustment process based on an adaptive power allocation algorithm, including:

[0017] Set the power adjustment step ΔP, adjust the grid-connected power P(t) in sequence, record the system response time and steady-state error after each power adjustment, use the adaptive power allocation algorithm based on PI control to adjust the PI control parameters, and calculate the system response time t res , that is, the time required for the power to reach more than 95% of the set value:

[0018] Among them, t is the time variable, P measured (t) is the actual power measured, P setis the target power setting value;

[0019] If t res If the power response time is >200ms, adjust the PI parameters or add a prediction compensation link to improve the power response speed.

[0020] As a preferred solution of the method for detecting the grid-connected and grid-connected capabilities of the grid-connected energy storage system described in the present invention, voltage disturbances of different amplitudes are applied to observe the response of the energy storage system, and a hierarchical voltage compensation algorithm is used to test whether the system can operate stably and maintain active power output, including: applying a mild voltage disturbance, the energy storage system first uses reactive power compensation to increase the voltage level by injecting a certain amount of reactive power into the grid, the active power remains basically unchanged, and the system supplies power stably; applying a moderate voltage disturbance, the system starts to dynamically adjust the active power output to ensure that the grid-connected voltage is as stable as possible, while maintaining the supply of some active power. In response, the energy storage converter adjusts its working mode and dynamically allocates the ratio of reactive to active power to avoid excessive power fluctuations affecting grid stability. When severe voltage disturbances are applied, the system enters low voltage ride-through mode to enhance the grid support capability and maintain short-term grid-connected operation. The DC bus voltage regulation of the energy storage system is started to support the grid voltage by adjusting the energy release rate. If the voltage drop lasts for a long time, the system reduces some active power output. When extreme voltage drops are applied, if the voltage drop is large and lasts for more than the set time, the system determines that the grid is abnormal and enters island mode detection. The system temporarily stops grid-connected power supply and switches to independent operation mode.

[0021] As a preferred solution of the method for detecting the grid-connected and grid-connected capabilities of the grid-connected energy storage system described in the present invention, voltage drops are divided into three levels: mild drop, moderate drop, and severe drop. Mild drop is a drop of 0.1pu-0.3pu or a drop to 0.7pu-0.85pu, moderate drop is a drop of 0.3pu-0.5pu or a drop to 0.5pu-0.7pu, and severe drop is a drop of 0.5pu-1p.u or a drop to 0p.u-0.5pu.

[0022] As a preferred solution of the method for detecting the networking and grid-connection capabilities of the grid-connected energy storage system described in the present invention, the method includes: simulating the disconnection of the main power grid to detect whether the energy storage system recognizes and enters the island mode, and using an improved positive and negative sequence impedance measurement method to improve the island detection speed, including: collecting the three-phase voltage and current of the energy storage system, calculating the positive sequence component and the negative sequence component, calculating the positive and negative sequence impedance of the system, setting a threshold, and when the rate of change of the threshold exceeds the set value, the system determines that it has entered the island mode. If the rate of change of the negative sequence impedance exceeds the set threshold, the system is immediately determined to have entered the island mode, and a secondary verification is performed in combination with the changes in frequency, phase and voltage amplitude; entering the independent power supply mode, maintaining the power supply to the local load, adjusting the output power to match the load demand, and continuously and stably supplying power if the battery power is sufficient; if the power is insufficient, performing power dispatch or issuing a low power alarm; reconnecting to the grid after the power grid is restored, monitoring the recovery of the main power grid, confirming that the voltage and frequency are stable, reconnecting to the grid, and ensuring phase, frequency and amplitude matching with the main power grid through grid-connected synchronous control.

[0023] A device for detecting the grid-building and grid-connection capabilities of a grid-building energy storage system includes a grid-building capability detection module for setting up a test environment, configuring the energy storage system to be tested, disconnecting the energy storage system from the external grid, testing whether it can independently start up and establish a stable grid voltage, and recording the voltage establishment time, steady-state error, and fluctuation. A nonlinear mixed load group containing variable resistance, inductance, and capacitance is connected, and a 20%-100% step load disturbance is applied. The dynamic response characteristics of the energy storage system to different load changes are detected based on adaptive droop coefficient adjustment. A dynamic power compensation algorithm is used to ensure that voltage and frequency remain stable under load fluctuations. A sudden load is applied to detect the recovery time of the energy storage system under test, which should be ≤200ms.

[0024] The grid-connected capability detection module: Before the energy storage system switches to grid-connected mode, it should adjust its own voltage, frequency, and phase, gradually increasing or decreasing the grid-connected power. This module tests the system's regulation and response capabilities within the 0-100% rated power range and optimizes the grid-connected power adjustment process based on an adaptive power allocation algorithm.

[0025] The dynamic characteristics test module is used to apply voltage disturbances of varying amplitudes to observe the energy storage system's response. Using a graded voltage compensation algorithm, it tests whether the system can operate stably and maintain active power output. It also simulates a main grid disconnect to detect whether the energy storage system recognizes and enters islanding mode, using an improved positive and negative sequence impedance measurement method to increase islanding detection speed.

[0026] The beneficial effects of the present invention are as follows: The present invention utilizes an improved positive- and negative-sequence impedance measurement algorithm, enabling faster detection of main grid disconnection and significantly shortening island detection time. By analyzing the changing trends of positive- and negative-sequence impedance in real time, misjudgments due to load changes are effectively avoided, improving the accuracy of island detection. Upon detecting island mode, the system can quickly switch to independent operation mode, ensuring that voltage and frequency are within the set range. A hierarchical voltage compensation algorithm is employed to dynamically adjust power output as load changes occur, ensuring stable power quality in the system under island mode and reducing voltage and frequency fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 This is a flow chart of a method for detecting the networking and grid-connection capabilities of a grid-type energy storage system provided in an embodiment of the present invention.

[0029] Figure 2 This is a structural diagram of a device for detecting the networking and grid-connected capability of a grid-type energy storage system provided in an embodiment of the present invention.

[0030] Figure 3 The figure schematically shows a structural diagram of a medium according to an embodiment of the present invention.

[0031] Figure 4 The figure schematically shows a structural diagram of a computing device according to an embodiment of the present invention.

[0032] In the drawings, the same or corresponding reference numerals denote the same or corresponding parts. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0036] Implementation Examples

[0037] Reference below Figure 1 , Figure 1 This is a flow chart of a method for detecting the networking and grid-connection capabilities of a grid-connected energy storage system according to an embodiment of the present invention. It should be noted that the embodiments of the present invention can be applied to any applicable scenario.

[0038] Figure 1 The process of the method for detecting the networking and grid-connection capability of a grid-type energy storage system provided by an embodiment of the present invention includes:

[0039] S1: Build a test environment, configure the energy storage system to be tested, disconnect the energy storage system from the external power grid, test whether it can start independently and establish a stable voltage, and record the voltage establishment time, steady-state error, and fluctuation.

[0040] Preferably, the self-starting mechanism of the energy storage system is triggered to observe whether the converter starts normally and record the self-test time of the converter during the startup process; the converter starts and enters the grid-forming mode and starts to output voltage, records the time series from control enable to voltage stabilization, collects the output voltage waveform, analyzes the rise rate and overshoot; uses FFT spectrum analysis to analyze the harmonic content of the voltage waveform, calculates the total harmonic distortion rate, and observes whether the voltage has low-frequency oscillations or high-frequency spikes.

[0041] Furthermore, use an oscilloscope or high-speed data acquisition system to collect transient process data from 0V to steady-state voltage. Select the time interval t when the voltage rises from 10% to 90% of the rated value (e.g. 230V rated voltage, corresponding to 23V~207V). rise Calculate the ascent rate S rise :

[0042]

[0043] Among them, V 90% =207V, V 10% =23V, t 90% and t 10% are the time points at which the corresponding voltages are reached;

[0044] Calculate the voltage overshoot amplitude:

[0045]

[0046] Among them, V max is the peak voltage, V steady is the steady-state voltage;

[0047] If the overshoot exceeds 5% of the steady-state value, the control algorithm needs to be optimized. Test under no-load conditions, increase the voltage from 0V to 230V, and record key data. The time to reach the 10% voltage point (23V) is 2ms, the time to reach the 90% voltage point (207V) is 6ms, and the peak voltage V max =245V, steady-state voltage V steady =230V, calculate the rise rate S rise =46V / ms, overshoot amplitude OverShoot=6.52%, overshoot is greater than 5%, and the converter PWM parameters and filter design need to be optimized.

[0048] Furthermore, an oscilloscope or a data acquisition card is used to record the output voltage waveform during steady-state operation.

[0049] Set the sampling frequency f s At least 10 times the fundamental frequency (e.g. fundamental frequency 50Hz, then f s ≥500Hz).

[0050] Perform fast Fourier transform on the collected voltage signal V(t) to obtain the harmonic voltage amplitudes V1, V2, V3, ... V n , calculate the total harmonic distortion (THD):

[0051]

[0052] Among them, V1 is the fundamental voltage amplitude, V2, V3, ..., V n is the voltage amplitude of each harmonic;

[0053] Sampling frequency f s =10kHz, record 500ms voltage data, perform FFT analysis: fundamental wave amplitude V1=230V,

[0054] Harmonic amplitude V2 = 5V (100Hz), V3 = 3V (150Hz), V4 = 2V (200Hz), calculated THD = 2.68%;

[0055] The results are compliant with IEEE 519 standards.

[0056] Use the FFT spectrum to observe whether there are: low-frequency oscillations (2Hz-20Hz). If the amplitude is high, the voltage control loop parameters need to be optimized. High-frequency spikes (above 10kHz) indicate converter switching noise or parasitic oscillations. Adjust the PWM modulation or add a filter. If the low-frequency oscillations have no obvious harmonic components, the system is not oscillating.

[0057] The high-frequency spikes have obvious peaks in the 20kHz and 40kHz frequency bands, indicating that the noise is caused by the high-frequency switching of the converter and the filter design needs to be optimized.

[0058] S2: Connect a nonlinear mixed load group containing variable resistance, inductance, and capacitance to test the system's response to different load changes. Use a dynamic power compensation algorithm to ensure that voltage and frequency remain stable under load fluctuations. Apply a sudden load change and test the recovery time of the energy storage system under test. The recovery time should be ≤ 200ms.

[0059] Preferably, the voltage, frequency and total harmonic distortion of the energy storage system in the no-load state are recorded, the load is gradually increased by 10%-50%-100% of the rated power, and the voltage drop amplitude, frequency deviation and recovery time T are measured. rec ;

[0060] Connect a transformer and an inductive load, gradually increase the power of the inductive load, record the current hysteresis angle θ and the voltage drop amplitude, and observe the frequency fluctuation;

[0061] Connect a high-power capacitor bank, gradually adjust the capacitive load power, record the current lead angle θ and voltage fluctuations, and optimize voltage stability by adjusting the converter reactive output.

[0062] Preferably, the voltage recovery time is calculated using the voltage change model calculation formula as follows:

[0063] Where V(t) is the instantaneous voltage, V set is the set voltage, ΔV is the voltage deviation, τ is the time constant, t is the time variable, is an exponential decay term;

[0064] The frequency change calculation formula is as follows:

[0065]

[0066] Where f(t) is the instantaneous frequency, f set is the set frequency, Δf is the frequency deviation, τ is the frequency recovery time constant, t is the time variable, is an exponential decay term;

[0067] The voltage and frequency change data are extracted by a high-speed oscilloscope to calculate the voltage recovery time T rec and frequency recovery time T f-rec , MATLAB is used to fit the data, and then the time constants τ and τ are fitted by the least squares method. f , then determine the recovery time and set T re and T f-recThe measured values ​​are X and Y. If X, Y ≤ 200ms, the test passes; otherwise, the compensation strategy is adjusted.

[0068] Furthermore, when the voltage deviation drops to 5% of the set value, recovery is complete: T rec ≈3τ, when the frequency deviation drops to 5% of the set value, recovery is complete: T f-rec ≈3τ f ;

[0069] Use a high-speed oscilloscope to record the voltage and frequency waveforms after a sudden load increase or decrease. Set the sampling rate to ≥ 100kHz, record the waveform data V(t) and f(t), import the oscilloscope data into MATLAB, and use the least squares method to fit the exponential decay curve. MATLAB code example:

[0070] % Read data

[0071] data = load('voltage_data.txt'); % Read oscilloscope data

[0072] t = data(:,1); % time

[0073] V = data(:,2); % voltage

[0074] % Exponential fit

[0075] f = @(p, t) p(1) + p(2) * exp(-t / p(3)); % formula V(t) = Vset + ΔV *exp(-t / τ)

[0076] p0 = [V(end), V(1)-V(end), 0.1]; % Initial estimated parameters

[0077] params = lsqcurvefit(f, p0, t, V);

[0078] % Calculate recovery time Trec

[0079] tau = params(3);

[0080] T_rec = 3 * tau;

[0081] fprintf('Voltage recovery time Trec = %.2f ms\n', T_rec * 1000);

[0082] Calculate the time constants τ and τ f , calculate the recovery time T rec and Tf-rec , result analysis:

[0083]

[0084] Under 10%-50% load conditions, T rec and T f-rec The test passed if the recovery time was less than 200ms. At 100% load, the recovery time exceeded 200ms, which means the test failed. The compensation strategy needs to be optimized. By enhancing the energy storage system control strategy and adjusting the converter PI control parameters, the dynamic response speed can be improved. Reactive power compensation can be increased to reduce voltage drops. The frequency regulation algorithm can be optimized to reduce frequency fluctuations during large load changes. The optimized 100% load test results show that the voltage recovery time T rec Reduced to 195ms. Frequency recovery time T f-rec It dropped to 190ms, meeting the test standard.

[0085] S3: Before switching to grid-connected mode, the energy storage system should adjust its voltage, frequency, and phase, gradually increasing or decreasing the grid-connected power, and test the system's regulation and response capabilities within the 0-100% rated power range. The grid-connected power adjustment process should be optimized based on an adaptive power allocation algorithm.

[0086] Preferably, the power adjustment step ΔP is set, and the grid-connected power P(t) is adjusted in sequence. After each power adjustment, the response time and steady-state error of the system are recorded, and the PI control parameters are adjusted using the adaptive power allocation algorithm based on PI control. The system response time t is calculated. res , that is, the time required for the power to reach more than 95% of the set value:

[0087] Among them, t is the time variable, P measured (t) is the actual power measured, P set is the target power setting value;

[0088] If t res If the power response time is >200ms, adjust the PI parameters or add a prediction compensation link to improve the power response speed.

[0089] Furthermore, the initial grid-connected power P is set set , gradually increase the power, adjust the step size ΔP: small power adjustment (10% rated power), medium power adjustment (50% rated power), high power adjustment (100% rated power); use a high-speed data acquisition card to record the power change curve P measured (t), record the system response time t res Import power data, smooth the data, and remove noise. Use the least squares method to fit the exponential decay curve: % Read data

[0090] data = load('power_response.txt');

[0091] t = data(:,1); % time

[0092] P = data(:,2); % actual power

[0093] % Exponential fit

[0094] f = @(p, t) p(1) + p(2) * exp(-t / p(3)); % Formula P(t) = Pset + ΔP *exp(-t / τ)

[0095] p0 = [P(end), P(1)-P(end), 0.1]; % Initial estimated parameters

[0096] params = lsqcurvefit(f, p0, t, P);

[0097] % Calculate response time tres

[0098] tau = params(3);

[0099] T_res = 3 * tau;

[0100] fprintf('Power response time T_res = %.2f ms\n', T_res * 1000);

[0101] Calculate system response time t res , and determine whether it exceeds 200ms;

[0102] Result analysis:

[0103]

[0104] When adjusting the power to a small value (10% of rated power), t res Less than 200ms, the system response is qualified. When adjusting the power (50%-100% rated power), t res If it is greater than 200ms, the test fails and the control strategy needs to be optimized.

[0105] S4: Apply voltage disturbances of different amplitudes to observe the response of the energy storage system. Use a graded voltage compensation algorithm to test whether the system can operate stably and maintain active power output.

[0106] Preferably, when a mild voltage disturbance is applied, the energy storage system first adopts reactive power compensation, which increases the voltage level by injecting a certain amount of reactive power into the grid, keeps the active power basically unchanged, and provides stable power supply to the system; when a moderate voltage disturbance is applied, the system starts to dynamically adjust the active power output to ensure that the grid voltage is as stable as possible, while maintaining the supply of some active power. The energy storage converter adjusts the working mode and dynamically allocates the ratio of reactive power to active power to avoid excessive power fluctuations affecting the stability of the grid; when a severe voltage disturbance is applied, the system enters the low voltage ride-through mode to enhance the grid support capability and maintain short-term grid-connected operation. The DC bus voltage regulation of the energy storage system is started to support the grid voltage by adjusting the energy release rate. If the voltage drop lasts for a long time, the system reduces some active power output; when an extreme drop is applied, if the voltage drop is large and lasts for more than the set time, the system determines that the grid is abnormal and enters the island mode detection. The system temporarily stops the grid-connected power supply and switches to the independent operation mode.

[0107] Voltage drops are generally divided into three levels: mild voltage disturbance, moderate voltage disturbance and severe voltage disturbance. Mild voltage disturbance is a reduction of 0.1pu-0.3pu or to 0.7pu~0.85pu, moderate voltage disturbance is a reduction of 0.3pu-0.5pu or to 0.5pu~0.7pu, and severe voltage disturbance is a reduction of 0.5pu-1p.u or to 0p.u~0.5pu.

[0108] Furthermore, for a mild voltage disturbance (a small voltage drop while maintaining reactive power compensation), the experimental conditions are as follows: a 5%-10% voltage drop (e.g., from 220V to 200V) is applied. The energy storage system's response is observed, and the change in reactive power compensation is recorded. The magnitude of the voltage drop is detected to determine whether it is a mild drop. The energy storage converter calculates the reactive power demand and injects reactive power into the grid to increase the voltage level. Active power remains unchanged, ensuring stable power supply and not affecting load operation. The grid voltage recovery is recorded, and if it returns to normal, the system exits reactive power compensation mode.

[0109] Moderate voltage disturbance (dynamic adjustment of active power output) experimental conditions: Apply a 10%-20% voltage drop (e.g., 220V to 180V). Observe the active power adjustment and record the grid voltage change. Detect the magnitude of the voltage disturbance and enter moderate voltage disturbance response mode. The energy storage system begins adjusting active power output, appropriately reducing power supply to prevent high current impact on the grid. The energy storage converter dynamically allocates the ratio of reactive and active power to ensure that the voltage remains as stable as possible. Real-time monitoring of grid parameters is performed. If the voltage returns to normal, the system gradually restores active power output. Severe voltage disturbance (low voltage ride-through) experimental conditions: Apply a 20%-50% voltage drop (e.g., 220V to 120V). Observe whether the energy storage system enters low voltage ride-through mode and measure the energy release rate. Detect the magnitude of the voltage drop and enter LVRT mode to enhance the grid's support capabilities.

[0110] The energy storage system starts DC bus voltage regulation to optimize the energy release rate and prevent bus overvoltage or undervoltage.

[0111] Maintain grid-connected operation for a short period of time to stabilize the grid voltage. If the voltage recovers, the system will resume normal operation. If the voltage drop persists, reduce some of the active power output. Record changes in grid voltage and power during the LVRT process. Extreme voltage drop (islanding mode switching) experimental conditions: Apply a voltage drop of more than 50% (e.g., from 220V to 50V). Observe whether the energy storage system recognizes the grid anomaly and switches to islanding mode. Detect the magnitude and duration of the voltage drop. If it exceeds the set threshold, the system will determine that the grid is abnormal.

[0112] The energy storage system enters island mode for testing, analyzing load characteristics to determine whether independent operation is necessary. If the load is suitable, the energy storage system disconnects the grid connection and enters independent operation mode, continuing to supply power. The island mode operating status is recorded, and voltage and frequency stability is observed.

[0113] S5: Simulates a main grid disconnection to detect whether the energy storage system recognizes and enters islanding mode, and uses an improved positive and negative sequence impedance measurement method to increase the speed of islanding detection.

[0114] Preferably, the three-phase voltage and current of the energy storage system are collected, the positive sequence component and the negative sequence component are calculated, the positive and negative sequence impedance of the system are calculated, and a threshold is set. When the rate of change of the threshold exceeds the set value, the system determines that it has entered the island mode. If the rate of change of the negative sequence impedance exceeds the set threshold, the system is immediately determined to have entered the island mode, and a secondary verification is performed in combination with the changes in frequency, phase and voltage amplitude; enter the independent power supply mode, maintain the power supply to the local load, adjust the output power to match the load demand, and continue to supply power stably if the battery power is sufficient; if the power is insufficient, perform power dispatch or issue a low power alarm; after the power grid is restored, reconnect to the grid, monitor the recovery of the main power grid, confirm that the voltage and frequency are stable, reconnect to the grid, and ensure that the phase, frequency and amplitude match the main power grid through grid-connected synchronization control.

[0115] Furthermore, the three-phase voltage U of the energy storage system is collected a 、U b 、U c and three-phase current I a , I b , I c Calculate the positive sequence voltage V1, negative sequence voltage V2, and then calculate the positive and negative sequence impedance:

[0116]

[0117] Set the threshold change rate and calculate:

[0118] Set ΔZ1≥5% or ΔZ2≥10% to trigger islanding detection;

[0119] Calculate the positive and negative sequence impedances to determine whether the change rates ΔZ1 and ΔZ2 exceed the set thresholds. If ΔZ2 exceeds 10%, immediately enter island mode. Combined with the frequency change Δf, phase drift Δθ, and voltage change ΔV, perform secondary verification: If Δf>0.2Hz, or Δθ>10°, or ΔV>10%, further confirm the island state and switch the energy storage system to independent power supply mode. Cut off the grid connection point switch and the energy storage system switches to independent power supply. Adjust the output power to match the local load demand P out =P load , monitor the battery SOC (remaining capacity) to ensure stable power supply: if SOC>30%, continuous power supply; if SOC<30%, the system enters power scheduling mode: reduce load power or issue a low battery alarm.

[0120] After introducing the method of the exemplary embodiment of the present invention, next, reference is made to Figure 2A device for detecting the grid-connection and grid-connection capabilities of a grid-connected energy storage system according to an exemplary embodiment of the present invention is described. The device includes: a grid-connection capability detection module for establishing a test environment, configuring the energy storage system to be tested, disconnecting the energy storage system from the external grid, testing whether it can independently start up and establish a stable voltage, and recording the voltage establishment time, steady-state error, and fluctuation; connecting a nonlinear mixed load group containing variable resistance, inductance, and capacitance, applying a 20%-100% step load disturbance, detecting the dynamic response characteristics of the energy storage system to different load changes based on adaptive droop coefficient adjustment, using a dynamic power compensation algorithm to ensure that the voltage and frequency remain stable under load fluctuations, applying a sudden load, and detecting the recovery time of the energy storage system under test, which should be ≤200ms; a grid-connection capability detection module for detecting the grid voltage, frequency, and phase before the energy storage system is connected to the grid, gradually increasing or decreasing the grid-connected power, testing the system's regulation and response capabilities within the range of 0-100% rated power, and optimizing the grid-connected power adjustment process based on an adaptive power allocation algorithm;

[0121] The dynamic characteristics test module applies voltage disturbances of different amplitudes to observe the dynamic response of the energy storage system under test. It uses a graded voltage compensation algorithm to test whether the system can operate stably and maintain active power output.

[0122] Simulate a main grid disconnection to detect whether the energy storage system recognizes and enters islanding mode, and use an improved positive and negative sequence impedance measurement method to increase the speed of islanding detection.

[0123] After introducing the method and apparatus of the exemplary embodiment of the present invention, the following is a reference to Figure 3 For a description of a computer-readable storage medium according to an exemplary embodiment of the present invention, please refer to Figure 3The computer-readable storage medium shown is a CD-ROM 30, on which a computer program (i.e., a program product) is stored. When the computer program is executed by a processor, it will implement the steps described in the above method implementation, such as building a test environment, configuring the energy storage system to be tested, disconnecting the energy storage system from the external power grid, testing whether it can start independently and establish a stable voltage, and recording the voltage establishment time, steady-state error, and fluctuation; connecting a nonlinear mixed load group with variable resistance, inductance, and capacitance to test the system's response to different load changes, using a dynamic power compensation algorithm to ensure that the voltage and frequency remain stable under load fluctuations, applying a sudden load, detecting the energy storage system's recovery time, and using time domain The response analysis method specifies a recovery time of ≤200ms. Before the energy storage system switches to grid-connected mode, it should adjust its voltage, frequency, and phase, gradually increasing or decreasing the grid-connected power to test the system's regulation and response capabilities within the 0-100% rated power range. The grid-connected power adjustment process is optimized based on an adaptive power allocation algorithm. Voltage disturbances of varying amplitudes are applied to observe the dynamic response of the energy storage system under test. A graded voltage compensation algorithm is used to test whether the system can operate stably and maintain active power output. A main grid disconnection is simulated to detect whether the energy storage system recognizes and enters islanding mode. An improved positive and negative sequence impedance measurement method is used to increase the speed of islanding detection. The specific implementation methods of each step are not repeated here.

[0124] It should be noted that examples of the computer-readable storage medium may also include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other optical or magnetic storage media, which are not listed here one by one.

[0125] After introducing the method, apparatus and medium of the exemplary embodiment of the present invention, the following is a reference to Figure 4 A computing device for detecting the grid-building and grid-connection capabilities of a grid-building energy storage system according to an exemplary embodiment of the present invention.

[0126] Figure 4 A block diagram is shown of an exemplary computing device 40 , which may be a computer system or server, suitable for implementing embodiments of the present invention. Figure 4 The computing device 40 shown is only an example and should not limit the functionality and scope of use of the embodiments of the present invention.

[0127] like Figure 4As shown, the components of computing device 40 may include, but are not limited to, one or more processors or processing units 401 , a system memory 402 , and a bus 403 connecting various system components (including system memory 402 and processing unit 401 ).

[0128] The computing device 40 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by the computing device 40, including volatile and non-volatile media, removable and non-removable media.

[0129] System memory 402 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 4021 and / or cache memory 4022. Computing device 40 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, ROM 4023 may be used to read and write non-removable, non-volatile magnetic media ( Figure 4 is not shown in the , usually referred to as "hard drive"). Although not in Figure 4 As shown in FIG4 , a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk"), and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) can be provided. In these cases, each drive can be connected to bus 403 via one or more data media interfaces. System memory 402 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of various embodiments of the present invention.

[0130] A program / utility 4025 having a set (at least one) of program modules 4024 may be stored, for example, in system memory 402. Such program modules 4024 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. Program modules 4024 generally implement the functions and / or methods described in the embodiments of the present invention.

[0131] The computing device 40 may also communicate with one or more external devices 404 (e.g., a keyboard, a pointing device, a display, etc.). Such communication may be performed via an input / output (I / O) interface 405. Furthermore, the computing device 40 may also communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network such as the Internet) via a network adapter 406. Figure 4 As shown, the network adapter 406 communicates with other modules (such as the processing unit 401) of the computing device 40 via the bus 403. Figure 4 Not shown, other hardware and / or software modules may be used in conjunction with computing device 40 .

[0132] The processing unit 401 executes various functional applications and data processing by running the programs stored in the system memory 402. For example, it sets up a test environment, configures the energy storage system to be tested, disconnects the energy storage system from the external power grid, tests whether it can start independently and establish a stable voltage, and records the voltage establishment time, steady-state error, and fluctuation. It connects a nonlinear mixed load group with variable resistance, inductance, and capacitance to test the system's response to different load changes, uses a dynamic power compensation algorithm to ensure that the voltage and frequency remain stable under load fluctuations, applies a sudden load, and detects the recovery time of the energy storage system. Using the time domain response analysis method, the recovery time should be ≤20 0ms; before the energy storage system switches to grid-connected mode, it should adjust its own voltage, frequency, and phase, gradually increasing or decreasing the grid-connected power, testing the system's regulation and response capabilities within the 0-100% rated power range, and optimizing the grid-connected power adjustment process based on the adaptive power allocation algorithm; apply voltage disturbances of varying amplitudes to observe the dynamic response of the energy storage system under test, and use a graded voltage compensation algorithm to test whether the system can operate stably and maintain active power output; simulate a main grid disconnection to detect whether the energy storage system recognizes and enters islanding mode, and use an improved positive and negative sequence impedance measurement method to increase the speed of islanding detection; the specific implementation methods of each step are not repeated here.

[0133] The specific implementation of each step will not be repeated here. It should be noted that while the detailed description above mentions several units / modules or sub-units / sub-modules of the synchronous escape wiring device based on multiple commodity flows, this division is merely exemplary and not mandatory. In practice, according to embodiments of the present invention, the features and functions of two or more units / modules described above may be embodied in a single unit / module. Conversely, the features and functions of a single unit / module described above may be further divided to be embodied by multiple units / modules.

[0134] In the description of the present invention, it should be noted that the terms “first”, “second” and “third” are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0135] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0136] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. There may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed may be through some communication interface, indirect coupling or communication connection of devices or units, which may be electrical, mechanical or other forms.

[0137] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0138] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0139] If the functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media capable of storing program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0140] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

[0141] Furthermore, although the operations of the method of the present invention are described in a particular order in the accompanying drawings, this does not require or imply that these operations must be performed in this particular order, or that all illustrated operations must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

Claims

1. A method for detecting the grid-connection and grid-connection capabilities of a grid-connection energy storage system, characterized in that: include: Network-building mode startup test: Build a test environment, configure the energy storage system to be tested, disconnect the energy storage system from the external grid, test whether it can independently start up and establish a stable voltage, and record the voltage establishment time, steady-state error, and fluctuation. Multimodal load disturbance test: Connect a nonlinear mixed load group containing variable resistance, inductance, and capacitance, apply a 20%-100% step load disturbance, and test the dynamic response characteristics of the energy storage system to different load changes based on adaptive droop coefficient adjustment. Use a dynamic power compensation algorithm to ensure that voltage and frequency remain stable under load fluctuations. Apply a sudden load change and test the recovery time of the energy storage system under test. The recovery time should be ≤200ms. Before switching to grid-connected mode, the energy storage system should adjust its voltage, frequency, and phase, gradually increasing or decreasing the grid-connected power. The system's regulation and responsiveness should be tested within a 0-100% rated power range. The grid-connected power adjustment process should be optimized using an adaptive power allocation algorithm. Voltage support and regulation capability test: Apply voltage disturbances of varying magnitudes to observe the dynamic response of the energy storage system under test. Utilize a graded voltage compensation algorithm to test whether the system can operate stably and maintain active power output. Simulate a main grid disconnection to detect whether the energy storage system recognizes and enters islanding mode, and use an improved positive and negative sequence impedance measurement method to increase the speed of islanding detection.

2. The method for detecting the grid-connected and grid-connected capabilities of a grid-connected energy storage system according to claim 1, wherein: The grid-building mode startup test disconnects the energy storage system from the external grid to test whether it can independently start up and establish a stable grid voltage. The voltage establishment time, steady-state error, and fluctuation are recorded, including: Trigger the energy storage system's self-start mechanism, observe whether the converter starts normally, and record the converter's self-test time during the startup process. The converter starts and enters the grid-forming mode, begins to output voltage, and records the time series from control enable to voltage stabilization. Collect the output voltage waveform, and analyze the rise rate and overshoot. Use FFT spectrum analysis to analyze the harmonic content of the voltage waveform, calculate the total harmonic distortion rate, and observe whether the voltage has low-frequency oscillations or high-frequency spikes.

3. The method for detecting the grid-connected and grid-connected capabilities of a grid-connected energy storage system according to claim 1, wherein: The multi-modal load disturbance test connects a nonlinear mixed load group containing variable resistance, inductance, and capacitance to test the system's dynamic response characteristics to different load changes. A dynamic power compensation algorithm is used to ensure that voltage and frequency remain stable under load fluctuations, including: Record the voltage, frequency and total harmonic distortion of the energy storage system in the no-load state, gradually increase the load from 10% to 50% to 100% of the rated power, and measure the voltage drop amplitude, frequency deviation and recovery time T rec ; Connect a transformer and an inductive load, gradually increase the power of the inductive load, record the current hysteresis angle θ and the voltage drop amplitude, and observe the frequency fluctuation; Connect a high-power capacitor bank, gradually adjust the capacitive load power, record the current lead angle θ and voltage fluctuations, and optimize voltage stability by adjusting the converter reactive output.

4. The method for detecting the network construction and grid connection capability of a grid-connected energy storage system according to claim 1, wherein: The process of applying a sudden load and detecting the energy storage system recovery time using a time domain response analysis method to calculate the recovery time to be ≤ 200ms includes: Calculate the voltage recovery time and the voltage change model calculation formula as follows: , Where V(t) is the instantaneous voltage, V set is the set voltage, ΔV is the voltage deviation, τ is the time constant, t is the time variable, is an exponential decay term; The frequency change calculation formula is as follows: ， Where f(t) is the instantaneous frequency, f set is the set frequency, Δf is the frequency deviation, τ is the frequency recovery time constant, t is the time variable, is an exponential decay term; The voltage and frequency change data are extracted through high-precision data acquisition, measurement and analysis equipment to calculate the voltage recovery time T rec and frequency recovery time T f-rec , MATLAB is used to fit the data, and then the time constants τ and τ are fitted by the least squares method. f , and then determine the recovery time, set T re and T f-rec The measured values ​​are X and Y. If X, Y ≤ 200ms, the test passes; otherwise, the compensation strategy is adjusted.

5. The method for detecting the grid-connected and grid-connected capabilities of a grid-connected energy storage system according to claim 1, wherein: The stepwise increase or decrease of the grid-connected power tests the system's regulation and response capabilities within the 0-100% rated power range, and optimizes the grid-connected power adjustment process based on an adaptive power allocation algorithm, including: Set the power adjustment step ΔP, adjust the grid-connected power P(t) in sequence, record the system response time and steady-state error after each power adjustment, use the adaptive power allocation algorithm based on PI control to adjust the PI control parameters, and calculate the system response time t res , that is, the time required for the power to reach more than 95% of the set value: , Among them, t is the time variable, P measured (t) is the actual power measured, P set is the target power setting value; If t res If the power response time is >200ms, adjust the PI parameters or add a prediction compensation link to improve the power response speed.

6. The method for detecting the grid-connected and grid-connected capabilities of a grid-connected energy storage system according to claim 1, wherein: The method of applying voltage disturbances of different amplitudes, observing the response of the energy storage system, and using a hierarchical voltage compensation algorithm to test whether the system can operate stably and maintain active power output includes: When a mild voltage disturbance is applied, the energy storage system first uses reactive power compensation to increase the voltage level by injecting a certain amount of reactive power into the grid, while the active power remains basically unchanged and the system provides stable power supply. When a moderate voltage disturbance is applied, the system begins to dynamically adjust the active power output to ensure that the grid voltage is as stable as possible while maintaining the supply of some active power. The energy storage converter adjusts its operating mode and dynamically allocates the ratio of reactive power to active power to prevent excessive power fluctuations from affecting grid stability. When a severe voltage disturbance is applied, the system enters low voltage ride-through mode to enhance the grid support capability and maintain short-term grid-connected operation. The energy storage system starts DC bus voltage regulation and supports the grid voltage by adjusting the energy release rate. If the voltage drop lasts for a long time, the system reduces some active power output. When an extreme voltage drop is applied, if the voltage drop is large and lasts for more than the set time, the system determines that the grid is abnormal and enters island mode detection. The system temporarily stops grid-connected power supply and switches to independent operation mode.

7. The method for detecting the grid-connected and grid-connected capabilities of a grid-connected energy storage system according to claim 6, wherein: The voltage drop is divided into three levels: mild drop, moderate drop and severe drop. The mild drop is a drop of 0.1pu-0.3pu or a drop to 0.7pu~0.85pu, the moderate drop is a drop of 0.3pu-0.5pu or a drop to 0.5pu~0.7pu, and the severe drop is a drop of 0.5pu-1p.u or a drop to 0p.u~0.5pu.

8. The method for detecting the grid-connected and grid-connected capabilities of a grid-connected energy storage system according to claim 1, wherein: The simulated main grid disconnection is used to detect whether the energy storage system has identified and entered the islanding mode, and the islanding detection speed is increased by using an improved positive and negative sequence impedance measurement method, including: Collect the three-phase voltage and current of the energy storage system, calculate the positive sequence component and negative sequence component, calculate the positive and negative sequence impedance of the system, set the threshold, and when the rate of change of the threshold exceeds the set value, the system determines that it has entered the island mode. If the negative sequence impedance change rate exceeds the set threshold, the system is immediately judged to have entered island mode, and a secondary verification is performed in combination with the frequency, phase and voltage amplitude changes; Enter independent power supply mode, maintain power supply to the load connected to the energy storage system, adjust the output power to match the load demand, and provide continuous and stable power supply if the battery power is sufficient; if the power is insufficient, perform power dispatch or issue a low-battery alarm; reconnect to the grid after the power grid is restored, monitor the recovery of the main grid, confirm that the voltage and frequency are stable, and reconnect to the grid. Through grid-connected synchronization control, ensure that the phase, frequency, and amplitude match those of the main grid.

9. A device for detecting the network construction and grid connection capability of a network-type energy storage system, characterized in that: include: The network capability test module is used to build a test environment, configure the energy storage system to be tested, disconnect the energy storage system from the external grid, test whether it can independently start up and establish a stable voltage, and record the voltage establishment time, steady-state error, and fluctuation. It also connects a nonlinear mixed load group containing variable resistance, inductance, and capacitance to test the dynamic response characteristics of the energy storage system to different load changes. It uses a dynamic power compensation algorithm to ensure that the voltage and frequency remain stable under load fluctuations. It also applies a sudden load and tests the recovery time of the energy storage system under test. The recovery time should be ≤ 200ms. The grid-connection capability detection module is used to detect the grid voltage, frequency, and phase before the energy storage system switches to grid-connected mode. It gradually increases or decreases the grid-connected power to test the system's regulation and response capabilities within the 0-100% rated power range and optimize the grid-connected power adjustment process based on an adaptive power allocation algorithm. The dynamic characteristics test module is used to apply voltage disturbances of different amplitudes to observe the response of the energy storage system. It uses a graded voltage compensation algorithm to test whether the system can operate stably and maintain active power output. Simulate a main grid disconnection to detect whether the energy storage system recognizes and enters islanding mode, and use an improved positive and negative sequence impedance measurement method to increase the speed of islanding detection.

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