Control Method and System of Energy Storage Inverter under Unbalanced Grid Voltage

Abstract

The present invention relates to the technical field of energy storage converter control, and specifically discloses a control method and system for an energy storage converter under unbalanced grid voltage. The method includes: analyzing the grid stability characteristics and the state of grid energy storage devices under unbalanced grid voltage, determining whether the energy storage converter needs to be controlled and determining the grid fault response threshold, judging whether the energy storage converter needs to switch to the fault mode, simultaneously using synchronous coordinate transformation to convert the three-phase voltage signal into a DC component, using positive and negative sequence component extraction technology to separate the positive sequence and negative sequence components, and determining the adjustment schemes for the positive sequence and negative sequence components. The present invention solves the problems that the traditional control method lacks robustness to uncertain factors and dynamic environments, and the traditional control strategy is often fixed and difficult to adaptively adjust according to changes in grid conditions, ensuring that the response of the energy storage converter adapts to the changes in the grid and effectively improving the power quality of the grid.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage converter control, and specifically to a control method and system for an energy storage converter under unbalanced grid voltage. Background Art

[0002] The energy storage converter has a bidirectional power conversion function, that is, it can absorb electric energy from the grid to charge the energy storage system, and can also deliver the electric energy of the energy storage system to the grid. At the same time, the energy storage converter can achieve independent control of active and reactive power. Under unbalanced grid conditions, by precisely controlling the active and reactive power output of the energy storage converter, the three-phase voltage and current can be effectively balanced, and the impact of imbalance on the grid can be alleviated. With the large-scale access of renewable energy (such as wind power and photovoltaic), the problem of grid imbalance has become increasingly serious. Renewable energy generation is intermittent and volatile, which is likely to cause asymmetry of the grid voltage, resulting in three-phase imbalance of the grid. The randomness of loads and the asynchronous access of distributed energy sources may also cause grid imbalance. Grid imbalance will increase line losses, reduce grid efficiency, affect the safe operation of equipment, cause voltage fluctuations, and reduce power supply reliability. In severe cases, power outages may occur. Through appropriate control strategies, the imbalance problem can be alleviated, and the operation efficiency and stability of the grid can be improved.

[0003] At present, there are still some deficiencies in the research on the control of energy storage converters under unbalanced grid voltage. Specifically, the traditional control methods lack robustness to uncertain factors and dynamic environments. In practical applications, factors such as load fluctuations and distributed power fluctuations will cause continuous changes in grid conditions. Traditional control strategies show response lags or large errors under these conditions, and traditional control methods are often fixed control strategies, which are difficult to adaptively adjust according to changes in grid conditions, and the ability to improve power quality is limited. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a control method and system for an energy storage converter under unbalanced grid voltage, which can effectively solve the problems involved in the above background art.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0006] The first aspect of the present invention provides a control method for an energy storage converter under unbalanced grid voltage, including the following steps:

[0007] Based on the grid monitoring period stored in the database, analyze the grid stability characteristics under unbalanced grid voltage to obtain the grid stability characteristic determination factor;

[0008] Analyze the state of the grid energy storage device under unbalanced grid voltage based on the state data of the grid energy storage device and the grid stability characteristic determination factor to obtain the converter control determination factor. According to the converter control determination factor, determine whether the energy storage converter needs to be controlled and determine the grid fault response threshold:

[0009] If the energy storage converter does not need to be controlled, enter the next cycle of grid monitoring;

[0010] If the energy storage converter needs to be controlled, analyze the grid fault characteristics under unbalanced grid voltage, and combine with the grid fault response threshold to determine whether the energy storage converter needs to switch to the fault mode;

[0011] In the fault mode, monitor the grid voltage under unbalanced grid voltage, obtain the amplitude and phase of the grid voltage, use synchronous coordinate transformation to convert the three-phase voltage signal into a DC component, use positive and negative sequence component extraction technology to separate the positive and negative sequence components from the DC component, and determine the positive and negative sequence component adjustment scheme.

[0012] As a further method, analyze the grid stability characteristics under unbalanced grid voltage to obtain the grid stability characteristic determination factor. The specific analysis process is as follows: Obtain the grid stability characteristic data, which specifically includes the grid voltage unbalance degree, the occurrence frequency of grid voltage sag events, and the grid voltage fluctuation frequency; Based on the obtained grid stability characteristic data, comprehensively analyze to obtain the grid stability characteristic determination factor, and the grid stability characteristic determination factor is used as the analysis basis for determining whether the energy storage converter needs to be controlled and determining the grid fault response threshold.

[0013] As a further method, analyze the state of the grid energy storage device under unbalanced grid voltage based on the state data of the grid energy storage device and the grid stability characteristic determination factor to obtain the converter control determination factor, specifically including:

[0014] Obtain the state data of the grid energy storage device, which specifically includes the ratio of the battery capacity to the rated capacity, the cumulative number of battery charge and discharge cycles, and the output power factor of the energy storage converter;

[0015] Based on the obtained state data of the grid energy storage device, combined with the grid stability characteristic determination factor, comprehensively analyze to obtain the converter control determination factor, and the converter control determination factor is used as the analysis basis for determining whether the energy storage converter needs to be controlled and determining the grid fault response threshold.

[0016] As a further method, the process of determining whether the energy storage converter needs to be controlled and determining the grid fault response threshold according to the converter control determination factor is as follows:

[0017] Compare the energy storage converter control determination factor with the energy storage converter control determination threshold stored in the database;

[0018] If the energy storage converter control determination factor is not lower than the energy storage converter control determination threshold, the energy storage converter does not need to be controlled and enters the grid monitoring of the next cycle;

[0019] If the energy storage converter control determination factor is lower than the energy storage converter control determination threshold, the energy storage converter needs to be controlled. Store the energy storage converter control determination factor as a specified tag, and compare the specified tag with each set tag stored in the database one by one to determine the set tag that is the same as the specified tag, and obtain the corresponding grid fault response threshold stored in the database for this set tag.

[0020] As a further method, the specific analysis process of the energy storage converter control determination factor is as follows:

[0021] ;

[0022] In the formula, is the energy storage converter control determination factor, is the grid stability characteristic determination factor, is the ratio of the battery capacity to the rated capacity, is the cumulative number of charge and discharge cycles of the battery, is the output power factor of the energy storage converter, is the set compensation factor, is the set compensation factor, is the set compensation factor.

[0023] As a further method, analyze the grid fault characteristics under unbalanced grid voltage. The specific analysis process is as follows: Obtain grid fault characteristic data, which specifically includes the grid voltage sag duration, the total harmonic distortion rate of the grid, and the ratio of the sudden rise value of the grid voltage to the rated voltage; Based on the obtained grid fault characteristic data, comprehensively analyze to obtain the grid fault response factor, and the grid fault response factor is used as the analysis basis for judging whether the energy storage converter needs to switch to the fault mode.

[0024] As a further method, in combination with the grid fault response threshold, it is determined whether the energy storage converter needs to be switched to the fault mode. The specific analysis process is as follows: compare the grid fault response factor with the grid fault response threshold; if the grid fault response factor is not lower than the grid fault response threshold, the energy storage converter corresponding to this grid fault response factor does not need to be switched to the fault mode; if the grid fault response factor is lower than the grid fault response threshold, the energy storage converter corresponding to this grid fault response factor needs to be switched to the fault mode.

[0025] As a further method, obtain the amplitude and phase of the grid voltage, and use synchronous coordinate transformation to convert the three-phase voltage signal into a DC component. The specific analysis process is as follows: collect the three-phase voltage signal of the grid and obtain the instantaneous amplitude of the three-phase voltage and the grid phase , represents the instantaneous value of the phase A voltage, represents the instantaneous value of the phase B voltage, represents the instantaneous value of the phase C voltage. The three-phase balance condition is: ;

[0026] Use Clarke transformation and Park transformation to convert the three-phase voltage signal to the d-q rotating coordinate system:

[0027] Clarke transformation converts the three-phase voltage signal to the stationary coordinate system;

[0028] ;

[0029] ;

[0030] is the axis voltage component, is the axis voltage component;

[0031] Park transformation converts the voltage component in the coordinate system to the synchronously rotating rotating coordinate system;

[0032] ;

[0033] ;

[0034] is the axis voltage component, is the axis voltage component;

[0035] At In the rotating coordinate system, the grid voltage signal is regarded as a DC component and appears as a constant value under balanced conditions. and behave as constant values.

[0036] As a further method, the positive and negative sequence component extraction technique is used to separate the positive and negative sequence components, and the positive and negative sequence component adjustment schemes are determined. The specific analysis process is as follows: In the rotating coordinate system, based on a low-pass filter, and are low-pass filtered to extract the positive sequence d-axis voltage component and the positive sequence q-axis voltage component ;

[0037] The rotating coordinate system is transformed into an inverse synchronous rotating coordinate system, that is, based on the rotation frequency -ω of the negative sequence component, and and in the inverse synchronous rotating coordinate system are low-pass filtered based on a low-pass filter to extract the negative sequence d-axis voltage component and the negative sequence q-axis voltage component ;

[0038] The process of determining the positive sequence component adjustment scheme is as follows:

[0039] Active power control: Obtain the active power reference value stored in the database ;

[0040] ;

[0041] is the positive sequence d-axis current reference value;

[0042] Use a PI controller to compare the current d-axis current with to generate a d-axis current control signal to adjust the active power output;

[0043] Reactive power control: Obtain the reactive power reference value stored in the database ;

[0044] ;

[0045] is the positive sequence q-axis current reference value;

[0046] Use a PI controller to compare the current q-axis current with to generate a q-axis current control signal to adjust the reactive power output;

[0047] The process of determining the negative sequence component adjustment scheme is as follows:

[0048] Negative sequence current compensation: To balance the grid current, the negative sequence d-axis current component and the q-axis current component are set as the targets;

[0049] Using a PI controller, compare the current negative sequence d-axis current component and the negative sequence q-axis current component with the targets to obtain the control output negative sequence d-axis current control signal and the negative sequence q-axis current control signal , generate a compensation current to suppress the negative sequence current;

[0050] Negative sequence voltage compensation: To reduce the influence of the negative sequence voltage, the negative sequence d-axis voltage component and the q-axis voltage component are set as the targets;

[0051] Using a PI controller, compare the current negative sequence d-axis voltage component and the negative sequence q-axis voltage component with the targets to obtain the control output negative sequence d-axis voltage control signal and the negative sequence q-axis voltage control signal , adjust the output voltage to achieve voltage balance.

[0052] The second aspect of the present invention provides a control system of an energy storage converter under unbalanced grid voltage, including a stability characteristic determination factor acquisition module, an energy storage converter control judgment module, and a positive and negative sequence component adjustment scheme determination module, wherein:

[0053] The stability characteristic determination factor acquisition module is used to analyze the grid stability characteristics under unbalanced grid voltage based on the grid monitoring period stored in the database to obtain the grid stability characteristic determination factor;

[0054] The energy storage converter control judgment module is used to analyze the state of the grid energy storage device under unbalanced grid voltage based on the state data of the grid energy storage device and the grid stability characteristic determination factor to obtain the energy converter control determination factor, and judge whether the energy storage converter needs to be controlled according to the energy converter control determination factor and determine the grid fault response threshold:

[0055] If the energy storage converter does not need to be controlled, enter the next cycle of grid monitoring;

[0056] If the energy storage converter needs to be controlled, analyze the grid fault characteristics under unbalanced grid voltage, and combine the grid fault response threshold to determine whether the energy storage converter needs to switch to the fault mode;

[0057] The positive and negative sequence component adjustment scheme determination module is used to monitor the grid voltage under unbalanced grid voltage in the fault mode, obtain the amplitude and phase of the grid voltage, convert the three-phase voltage signal into a DC component using synchronous coordinate transformation, and use positive and negative sequence component extraction technology to separate the positive sequence and negative sequence components from the DC component, and determine the positive sequence and negative sequence component adjustment schemes.

[0058] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0059] (1) By providing a control method and system for an energy storage converter under unbalanced grid voltage, the present invention periodically analyzes the grid stability characteristics, extracts and analyzes the grid stability characteristic data, can timely identify problems such as voltage imbalance and voltage fluctuation in the grid, and the grid stability characteristic determination factor can help quickly identify potential imbalance or fluctuation trends, so as to issue early warnings. Through the analysis of the grid stability characteristics, more accurate determination factors can be obtained. According to the actual fluctuation situation of the grid and the state of the energy storage device, the grid fault response threshold is adjusted in real time to ensure that the response of the energy storage converter adapts to the changes of the grid, enhance the flexibility of the control strategy, provide active and reactive power support by adjusting the positive sequence component to stabilize the grid voltage; suppress the voltage imbalance of the grid and reduce the negative sequence component of the current by adjusting the negative sequence component. This can effectively improve the power quality of the grid and reduce the impact on electrical equipment.

[0060] (2) By analyzing the state of the grid energy storage device under unbalanced grid voltage and combining the grid stability characteristic determination factor, the present invention determines whether the energy storage converter needs to be controlled and determines the grid fault response threshold. The state of the energy storage device directly affects its regulation ability. Through the analysis of the state of the energy storage device, the energy storage converter can more accurately judge when and to what extent to intervene in the control, avoid blind regulation, and ensure the system stability. Combining the grid stability characteristic determination factor, the energy storage converter can dynamically adjust the control requirements according to the actual unbalance degree of the grid, ensure that the regulation response is fast and accurate, and help provide precise support when the grid fluctuates. In the case of combining the state of the energy storage device and the grid characteristic determination factor, the grid fault response threshold can be dynamically adjusted to flexibly judge the control requirements, and the energy storage converter can more effectively regulate the grid voltage. Description of the Drawings

[0061] The present invention will be further described with reference to the accompanying drawings. However, the embodiments shown in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the following drawings without creative efforts.

[0062] Figure 1 It is a schematic flowchart of the control method of the energy storage converter of the present invention under unbalanced grid voltage.

[0063] Figure 2 It is a schematic diagram of the module connection of the control system of the energy storage converter of the present invention under unbalanced grid voltage.

[0064] Figure 3 It is a flowchart for judging whether the energy storage converter needs to switch to the fault mode in the embodiment of the present invention. Specific embodiments

[0065] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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 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 belong to the scope of protection of the present invention.

[0066] Referring to Figure 1 As shown, the first aspect of the present invention provides a control method for an energy storage converter under unbalanced grid voltage, including: analyzing the grid stability characteristics under unbalanced grid voltage based on the grid monitoring period stored in the database to obtain a grid stability characteristic determination factor.

[0067] The specific analysis process is as follows: Obtain grid stability characteristic data, which specifically includes grid voltage unbalance, the occurrence frequency of grid voltage dip events, and grid voltage fluctuation frequency; based on the obtained grid stability characteristic data, comprehensively analyze to obtain a grid stability characteristic determination factor, and the grid stability characteristic determination factor is used as an analysis basis for judging whether the energy storage converter needs to be controlled and determining the grid fault response threshold.

[0068] Voltage unbalance refers to the asymmetry degree of three-phase voltage amplitude or phase in the power grid, expressed as the ratio of negative-sequence voltage to positive-sequence voltage. Voltage unbalance is generally obtained through a power quality analyzer or intelligent substation monitoring equipment. Voltage sag refers to the phenomenon that the voltage drops to between 10% and 90% of the rated voltage within a short time. The occurrence frequency of voltage sag events represents the number of voltage sags occurring in the power grid within a certain period, and the voltage sag event frequency can be obtained through a voltage monitor, power quality monitoring device or distribution automation terminal. Voltage fluctuation frequency represents the number of periodic or aperiodic fluctuations of the power grid voltage near the rated voltage, and the voltage fluctuation frequency is generally obtained by a power quality monitor or flicker meter.

[0069] In a three-phase power grid, when the voltage unbalance is relatively high, the voltage of a certain phase may be affected by an excessive load or a fault, resulting in a temporary voltage drop or fluctuation, thus causing an increase in the occurrence frequency of voltage sag events. When a voltage sag occurs in the power grid, especially a single-phase or two-phase voltage sag in a three-phase system, it is easy to cause three-phase asymmetry, resulting in an increase in voltage unbalance. Voltage unbalance will cause the asymmetry of current and voltage, resulting in an increase in volatility. For example, if the connection and disconnection of loads in the power grid are three-phase asymmetric, it will cause frequent voltage fluctuations. Therefore, when the voltage unbalance increases, the voltage fluctuation frequency will also increase accordingly. The occurrence of voltage sag events will cause a sudden drop and recovery of the voltage, thereby causing short-term voltage fluctuations. When the voltage sag frequency is relatively high, it will cause the voltage fluctuation frequency to increase accordingly, manifested as an enhanced voltage instability.

[0070] The voltage unbalance degree of the power grid, the occurrence frequency of voltage sag events and the voltage fluctuation frequency reflect the true stability of the power grid. The decision factors analyzed based on these characteristic data can accurately identify whether the power grid is in an unstable state, thus providing a reliable basis for whether to control the energy storage converter. Through the comprehensive analysis of multi-dimensional data, it can avoid misjudgment caused by the fluctuation of a single index, improve the recognition accuracy of the unstable condition of the power grid, and ensure that the energy storage converter only intervenes when necessary.

[0071] Based on the comprehensive characteristic analysis, the control strategy of the energy storage converter can be intelligentized. The fault response threshold can be dynamically set according to the decision factors, and the protection mechanism of the energy storage converter can be flexibly adjusted according to the severity and frequency of the fault. Based on the decision factors obtained from the comprehensive characteristic data analysis, automatic judgment and control can be realized, which helps to simplify the operation process of the energy storage converter and improve the automation level of power grid dispatching and energy storage system management.

[0072] The decision factors for the power grid stability characteristics, the specific analysis process is as follows:

[0073] ;

[0074] In the formula, is the determination factor for grid stability characteristics, is the grid voltage unbalance degree, is the occurrence frequency of grid voltage sag events, is the grid voltage fluctuation frequency, is the set compensation factor, is the set compensation factor, is the set compensation factor, is the natural constant.

[0075] It should be noted that the above determination factor for grid stability characteristics is calculated through the grid voltage unbalance degree, the occurrence frequency of grid voltage sag events, and the grid voltage fluctuation frequency. For After normalization, the voltage unbalance degree, voltage sag frequency, and voltage fluctuation frequency respectively reflect the health status of the grid from the aspects of grid symmetry, steady-state stability, and transient stability, and can more comprehensively measure the overall stability of the grid, avoiding misjudgment caused by a single index. By integrating different grid characteristic data to form a determination factor, a data-driven stability assessment method can be formed, which helps to realize the automatic management of smart grids, reduce human intervention. The calculated determination factor for grid stability characteristics can be used as the decision basis for the control of energy storage converters to ensure voltage stability and grid stability, and improve the reliability of power supply.

[0076] It should be noted that the above set compensation factor is obtained from the database. According to historical data, a mapping set of the grid voltage unbalance degree, the occurrence frequency of grid voltage sag events, the grid voltage fluctuation frequency in historical measurements and the compensation factor is established, and the corresponding compensation factor of the current is obtained.

[0077] It should be noted that the in the following text is also obtained through the mapping set of historical data and compensation factors established in the database, that is, the corresponding compensation factor is obtained according to the current data.

[0078] Based on the grid energy storage device status data and the determination factor for grid stability characteristics, analyze the status of the grid energy storage device under unbalanced grid voltage to obtain the control determination factor for the energy storage converter. According to the control determination factor for the energy storage converter, determine whether the energy storage converter needs to be controlled and determine the grid fault response threshold: If the energy storage converter does not need to be controlled, enter the next cycle of grid monitoring; if the energy storage converter needs to be controlled, analyze the grid fault characteristics under unbalanced grid voltage, combined with the grid fault response threshold, such asFigure 3 As shown, it is determined whether the energy storage converter needs to switch to the fault mode.

[0079] The specific analysis process is as follows: Obtain the state data of the grid energy storage device. The state data of the grid energy storage device specifically includes the ratio of the battery capacity to the rated capacity, the cumulative number of charge and discharge cycles of the battery, and the output power factor of the energy storage converter. Based on the obtained state data of the grid energy storage device and combined with the grid stability characteristic determination factor, comprehensively analyze to obtain the energy storage converter control determination factor. The energy storage converter control determination factor is used as the analysis basis for judging whether the energy storage converter needs to be controlled and determining the grid fault response threshold.

[0080] The ratio of the battery capacity to the rated capacity represents the percentage of the current remaining battery capacity to the rated capacity, which is used to evaluate the remaining life and health status of the battery and is obtained through the battery management system (BMS). The cumulative number of charge and discharge cycles of the battery represents the cumulative number of charge and discharge times of the battery, which is an important indicator of battery aging and is obtained through the battery management system (BMS). The output power factor of the energy storage converter represents the ratio of the active power to the apparent power of the output current of the energy storage converter, indicating the output efficiency and is obtained through the power converter control system (PCS) or the power quality monitor.

[0081] After the battery undergoes multiple charge and discharge cycles, it will gradually age, resulting in capacity attenuation. The more the number of cycles, the actual capacity of the battery (i.e., the current available capacity) usually decreases, thus causing the ratio of the battery capacity to the rated capacity to decrease. There is a negative correlation between the number of cycles and the capacity ratio. The increase in the number of cycles will lead to the decrease in the capacity ratio. The higher the ratio of the battery capacity to the rated capacity, the greater the available capacity of the battery. At this time, the energy storage system has a higher electric energy output capacity, and the energy storage converter can better control the output power factor to achieve a better coordination of active power and reactive power. When the capacity ratio decreases, the available capacity of the battery is insufficient, and the energy storage converter will be restricted while meeting the active power output demand, which may lead to a decrease in the reactive power compensation ability, thus affecting the power factor.

[0082] The output power factor of the energy storage converter can be used as a basis for judging its output characteristics. If the power factor is too low, it indicates that the reactive power output is relatively high, which may affect the system stability. By combining the power factor data, it can be ensured that the output of the converter meets the grid requirements. In the case of low capacity or high cycle times, the energy storage device can avoid unnecessary control, reduce the load on the device, effectively extend the battery life, optimize the use of the energy storage device, and the output power factor combined with the grid characteristic determination factor can effectively help identify whether the grid needs reactive power support. The energy storage converter can provide reactive power in a timely manner at low power factors, improving the voltage stability of the grid, thereby ensuring the power supply quality of the grid. According to the fault response threshold set by the control determination factor, the energy storage converter can flexibly adjust at different degrees of grid faults and perform multi-level responses.

[0083] Compare the energy storage converter control determination factor with the energy storage converter control determination threshold stored in the database; if the energy storage converter control determination factor is not lower than the energy storage converter control determination threshold, the energy storage converter does not need to be controlled and enters the next cycle of grid monitoring; if the energy storage converter control determination factor is lower than the energy storage converter control determination threshold, the energy storage converter needs to be controlled, store the energy storage converter control determination factor as a specified label, and compare this specified label with each set label stored in the database one by one to determine the set label that is the same as this specified label, and obtain the corresponding grid fault response threshold stored in the database for this set label.

[0084] By comparing the energy storage converter control determination factor with the preset control determination threshold, it can accurately judge whether the energy storage converter needs to intervene in control, ensuring that the regulation is only started when the grid is unbalanced or fluctuates beyond a specific degree, and avoiding unnecessary actions. By automatically judging and comparing the thresholds, the energy storage converter control is only started when necessary, avoiding frequent charge and discharge operations, reducing energy consumption and equipment wear, and extending the service life of the energy storage device. Each time the control determination factor is lower than the control determination threshold, the appropriate fault response threshold under the current conditions is automatically found through label comparison, ensuring the response accuracy and timeliness. The scheme ensures that the control action of the energy storage converter highly matches the degree of grid imbalance or fluctuation, preventing grid voltage fluctuations caused by over-response and further improving the stability and power quality of the grid.

[0085] Specifically, for the energy storage converter control determination factor, the specific analysis process is as follows:

[0086] ;

[0087] In the formula, is the energy storage converter control determination factor, is the grid stability characteristic determination factor, is the ratio of the battery capacity to the rated capacity, is the cumulative number of charge and discharge cycles of the battery, is the output power factor of the energy storage converter, is the set compensation factor, is the set compensation factor, is the set compensation factor.

[0088] It should be noted that the above energy storage converter control determination factor is calculated through the ratio of the battery capacity to the rated capacity, the cumulative number of charge and discharge cycles of the battery, the output power factor of the energy storage converter, and the power grid stability characteristic determination factor, and is normalized. The battery capacity ratio, the number of cycles, and the power factor respectively represent the battery health state, the service life, and the output efficiency, while the power grid stability characteristic determination factor reflects the operating state of the power grid. By integrating these factors to calculate the determination factor, the energy storage converter can obtain comprehensive information on the battery state and the power grid state, so as to make more accurate control decisions.

[0089] The battery capacity ratio and the cumulative number of charge and discharge cycles reflect the health status of the battery. The determination factor combined with the power grid demand can help judge to reduce the usage frequency when the battery state is poor, avoid frequent operations in the state of low battery efficiency or severe attenuation, and improve the overall working efficiency of the system. Combined with the power grid stability characteristic determination factor, the energy storage converter control determination factor can flexibly adjust the control strategy of the energy storage system according to the fluctuations of the power grid, and support the optimal dispatching of the smart grid.

[0090] Obtain the power grid fault characteristic data, which specifically includes the power grid voltage sag duration, the total harmonic distortion rate of the power grid, and the ratio of the sudden voltage rise value of the power grid to the rated voltage; based on the obtained power grid fault characteristic data, comprehensively analyze to obtain the power grid fault response factor, and the power grid fault response factor is used as the analysis basis for judging whether the energy storage converter needs to switch to the fault mode.

[0091] The power grid voltage sag duration refers to the duration during which the power grid voltage is lower than a certain proportion of the rated voltage within a certain time period, and the power grid voltage sag duration is usually obtained by a power quality analyzer or a voltage monitor. The total harmonic distortion rate of the power grid (is an index that measures the ratio of the harmonic components to the fundamental component in the voltage or current. The total voltage harmonic distortion rate is defined as the root mean square value of all harmonic components divided by the root mean square value of the fundamental component, and the total harmonic distortion rate is obtained by a power quality monitor or a harmonic analyzer. The ratio of the sudden voltage rise value of the power grid to the rated voltage is the ratio of the voltage rising instantaneously to a certain multiple of the rated voltage, usually called voltage swell, and the ratio of the voltage swell is usually obtained by a power quality monitoring device or a voltage monitor.

[0092] Voltage dips are usually accompanied by unstable system loads. Especially when there are a large number of power electronic devices (such as inverters, rectifiers) or non-linear loads in the power grid, voltage dips can cause fluctuations in the operating state of power equipment, generate additional harmonic currents, and increase the total harmonic distortion rate. Voltage dips and voltage swells usually occur alternately during load switching, large load start / stop, or after fault clearing. When a voltage dip occurs in one or more phases of the power grid (such as a short-circuit fault), a short-term voltage swell may occur during the recovery process. The possibility of a voltage swell increases when the duration of the voltage dip is longer.

[0093] Characteristic data such as the duration of the voltage dip, the total harmonic distortion rate, and the value of the voltage swell can reflect the degree of the power grid fault. By comprehensively analyzing these data, the obtained fault response factor can accurately judge the severity of the fault, thus ensuring that the response decision of the energy storage converter is based on the real power grid conditions. When the power grid fault reaches a certain level, the power grid fault response factor can trigger the energy storage converter to enter the fault mode, immediately reduce the output or cut off the connection, avoid equipment overload or damage, protect the safety of the energy storage system. The abnormal total harmonic distortion rate and voltage swell of the power grid usually affect the power quality. According to the fault response factor, the energy storage converter can switch to the fault mode when the harmonics and voltage anomalies are severe, thus avoiding the transmission of poor-quality electric energy to the power grid and reducing the interference to other power grid equipment. During a fault, the fault response factor can help the energy storage converter quickly switch to the fault mode, reduce the response delay, ensure that protective measures are taken in the shortest time, and support automatic fault identification and protection triggering.

[0094] The power grid fault response factor, the specific analysis process is as follows:

[0095] ;

[0096] In the formula, is the power grid fault response factor, is the duration of the power grid voltage dip, is the total harmonic distortion rate of the power grid, is the ratio of the power grid voltage swell value to the rated voltage, is the set compensation factor, is the set compensation factor, is the set compensation factor.

[0097] It should be noted that the above power grid fault response factor is calculated through the duration of the power grid voltage dip, the total harmonic distortion rate of the power grid, and the ratio of the power grid voltage swell value to the rated voltage. For Normalization is carried out. The voltage sag duration, voltage swell, and total harmonic distortion rate respectively reflect the instantaneous voltage anomalies and power quality conditions of the power grid, and can comprehensively evaluate the fault degree of the power grid, avoiding misjudgment caused by a single index. By calculating the fault response factor by integrating multiple indicators, misjudgment can be avoided, making the response factor more stable and accurate.

[0098] When the fault response factor is lower than a certain threshold, the energy storage system can enter the fault protection mode, and determine whether it is necessary to trigger the protection response by judging the size of the factor, thus ensuring the safety of the energy storage system and the power grid. Only when the comprehensive fault response factor exceeds the safety threshold, the protection is triggered, avoiding frequent switching of the energy storage converter to the fault mode, which helps to improve the stability and durability of the equipment. Voltage sags and swells often cause impacts on power equipment. Through timely monitoring and response by the fault response factor, the response of the energy storage system can be triggered during voltage anomalies, reducing the voltage impact on power equipment and extending the service life of the equipment.

[0099] Compare the power grid fault response factor with the power grid fault response threshold; if the power grid fault response factor is not lower than the power grid fault response threshold, the energy storage converter corresponding to this power grid fault response factor does not need to switch to the fault mode; if the power grid fault response factor is lower than the power grid fault response threshold, the energy storage converter corresponding to this power grid fault response factor needs to switch to the fault mode.

[0100] By setting the response threshold, it can be accurately judged whether the power grid is in a fault or abnormal state, avoiding the energy storage converter from mistakenly entering the fault mode when the power grid fluctuation is not serious, thereby improving the accuracy of fault judgment and the response flexibility of the energy storage system. The comparison between the power grid fault response factor and the threshold enables the energy storage converter to dynamically adapt to different fault degrees.

[0101] It does not enter the fault mode during slight fluctuations, but quickly switches the mode during severe faults, ensuring the intelligence and flexible response ability of the system. It only switches to the fault mode when the power grid fault response factor is lower than the threshold, avoiding frequent and unnecessary switching. Frequent switching of the energy storage converter will increase equipment wear and reduce its service life. Reasonably setting the response factor can reduce the load on the equipment and improve its operating life. When the power grid fault response factor is lower than the threshold, the energy storage converter switches to the fault mode and can immediately respond to provide the necessary support power to help the power grid restore stability. For fault situations such as voltage sags and overcurrents, the timely switching of the energy storage converter helps to reduce the impact of fluctuations on the power grid and improve the reliability of power quality and fault protection.

[0102] In the fault mode, the grid voltage under unbalanced grid voltage is monitored to obtain the amplitude and phase of the grid voltage. The three-phase voltage signal is transformed into a DC component using synchronous coordinate transformation, and the positive and negative sequence components are separated using the positive and negative sequence component extraction technique to determine the adjustment schemes for the positive and negative sequence components.

[0103] The specific analysis process is as follows: The three-phase voltage signals of the grid are collected to obtain the instantaneous amplitudes and the grid phase , represents the instantaneous value of the voltage of phase A, represents the instantaneous value of the voltage of phase B, represents the instantaneous value of the voltage of phase C. The three-phase balance condition is: ;

[0104] The three-phase voltage signal is transformed into the d-q rotating coordinate system using Clarke transformation and Park transformation:

[0105] Clarke transformation transforms the three-phase voltage signal into the stationary coordinate system;

[0106] ;

[0107] ;

[0108] is the axis voltage component, is the axis voltage component;

[0109] Park transformation transforms the voltage component in the coordinate system into the synchronously rotating rotating coordinate system;

[0110] ;

[0111] ;

[0112] is the axis voltage component, is the axis voltage component;

[0113] In the rotating coordinate system, the grid voltage signal is regarded as a DC component. Under balanced conditions, and appear as constant values.

[0114] In the d-q rotating coordinate system, the three-phase voltage signal is transformed into a constant DC component and For DC signals, control and calculation are simpler than for AC signals, which facilitates real-time power control of the energy storage converter and simplifies the control process. The phase differences of the three-phase voltage signals are unified in the same coordinate system through coordinate transformation, making the adjustment of the signals no longer affected by the phase differences, simplifying the calculation, improving the response speed and control accuracy. In the d-q coordinate system, the d-axis and q-axis represent the active power component and reactive power component of the power grid respectively.

[0115] By controlling and , independent adjustment of active power and reactive power can be achieved. Under balanced grid conditions in the d-q rotating coordinate system, and appear as constant values; if the grid is unbalanced or there are disturbances, these components will fluctuate. By monitoring and changes, the degree of grid imbalance can be identified and evaluated. The voltage signals in the d-q coordinate system appear as constant DC components in the balanced state. This characteristic can effectively suppress the influence of high-frequency harmonic components on power quality and improve the harmonic suppression ability of the system.

[0116] In the d-q rotating coordinate system, the voltage signal becomes a DC component, and the control system of the energy storage converter can respond faster to grid changes, achieving fast dynamic control and meeting the requirements of the smart grid for flexible control and fast response. The d-q coordinate system facilitates the extraction and separation of positive and negative sequence components under unbalanced grids, which provides a good basis for advanced control strategies (such as unbalance compensation and harmonic suppression).

[0117] In the rotating coordinate system, based on a low-pass filter, and are low-pass filtered to extract the positive sequence d-axis voltage component , and the positive sequence q-axis voltage component ;

[0118] Convert the rotating coordinate system to the inverse synchronous rotating coordinate system, that is, based on the rotation frequency -ω of the negative sequence component, and based on a low-pass filter, and in the inverse synchronous rotating coordinate system are low-pass filtered to extract the negative sequence d-axis voltage component and the negative sequence q-axis voltage component .

[0119] The process of determining the positive sequence component adjustment scheme is as follows: Active power control: Obtain the active power reference value stored in the database;

[0120] ;

[0121] is the positive-sequence d-axis current reference value;

[0122] Use a PI controller to compare the current d-axis current with to generate a d-axis current control signal to regulate the active power output;

[0123] Reactive power control: Obtain the reactive power reference value stored in the database ;

[0124] ;

[0125] is the positive-sequence q-axis current reference value;

[0126] Use a PI controller to compare the current q-axis current with to generate a q-axis current control signal to regulate the reactive power output.

[0127] The process of determining the negative-sequence component adjustment scheme is as follows: Negative-sequence current compensation: To balance the grid current, set the negative-sequence d-axis current component and the q-axis current component as the target; Use a PI controller to compare the current negative-sequence d-axis current component and the negative-sequence q-axis current component with the target to obtain the control output negative-sequence d-axis current control signal and the negative-sequence q-axis current control signal , generate a compensation current to suppress the negative-sequence current; Negative-sequence voltage compensation: To reduce the influence of the negative-sequence voltage, set the negative-sequence d-axis voltage component and the q-axis voltage component as the target; Use a PI controller to compare the current negative-sequence d-axis voltage component and the negative-sequence q-axis voltage component with the target to obtain the control output negative-sequence d-axis voltage control signal and the negative-sequence q-axis voltage control signal , adjust the output voltage to achieve voltage balance.

[0128] The d-axis current of the positive-sequence component is closely related to the active power. By setting the positive-sequence d-axis current reference value , the active power output can be accurately controlled. The PI controller compares the actual current with the reference value and generates an adjustment signal , ensure that the active power output meets the grid demand and improve the stability and efficiency of power transmission.

[0129] q-axis current of the positive sequence component For regulating reactive power, by setting the reactive power reference value

[0130] , it can meet the reactive power demand of the grid and improve the stability of the grid voltage. The reactive power regulation signal generated by the PI controller Helps to achieve reactive power compensation, improve the voltage quality and power quality of the grid. In the d-q coordinate system, the negative sequence d-axis current reference value and the q-axis current reference value are set so that the negative sequence current disappears or is minimized.

[0131] The PI controller suppresses the negative sequence current through the regulating signals and , which reduces the asymmetric current in the grid, effectively reduces the unbalance degree, thus protecting power equipment and improving power quality. Similarly, by setting the negative sequence d-axis voltage reference value and the q-axis voltage reference value as the target, the influence of the negative sequence voltage can be reduced. The negative sequence voltage control signal generated by the PI controller and are used to eliminate the imbalance of the negative sequence voltage, improve the voltage symmetry of the grid, and make the electric energy more stable and reliable.

[0132] Negative sequence current and voltage will increase the losses of power equipment, cause additional heating and vibration of equipment such as motors and transformers, and accelerate the aging of the equipment. By eliminating or suppressing the negative sequence component, the energy storage converter can reduce the additional losses of the equipment, extend its service life, and reduce the maintenance and replacement costs. An unbalanced grid may cause current overload or voltage abnormality of power equipment. Compensation of negative sequence current and voltage can prevent the equipment from working in an unsafe state for a long time and ensure the stable operation of power equipment within the rated parameters.

[0133] Eliminating or reducing negative sequence current and voltage helps to balance the grid, especially under the condition of large-scale unbalanced loads. Through the compensation strategy, the balance of the grid can be quickly restored, preventing the further spread of fluctuations or instabilities in the grid. When the grid is unbalanced, the negative sequence component will exacerbate the grid fluctuations and increase the fault risk. By suppressing the negative sequence component, the occurrence of these secondary faults can be prevented, ensuring the stable operation of the grid, especially providing guarantee for the power supply safety of sensitive loads and important equipment. In the event of sudden grid voltage fluctuations or unbalances, the energy storage converter can quickly respond based on the regulation scheme of positive and negative sequence components, provide stable active and reactive power support, achieve timely compensation for the grid, and improve the dynamic stability of the grid.

[0134] Referring to Figure 2 As shown, the second aspect of the present invention provides a control system of an energy storage converter under unbalanced grid voltage, including a stability characteristic determination factor acquisition module, an energy storage converter control judgment module, and a positive and negative sequence component adjustment scheme determination module.

[0135] The stability characteristic determination factor acquisition module is used to analyze the grid stability characteristics under unbalanced grid voltage based on the grid monitoring period stored in the database to obtain the grid stability characteristic determination factor.

[0136] The energy storage converter control judgment module is used to analyze the state of the grid energy storage device under unbalanced grid voltage based on the state data of the grid energy storage device and the grid stability characteristic determination factor to obtain the energy converter control determination factor, and judge whether the energy storage converter needs to be controlled according to the energy converter control determination factor and determine the grid fault response threshold: if the energy storage converter does not need to be controlled, it enters the next cycle of grid monitoring; if the energy storage converter needs to be controlled, it analyzes the grid fault characteristics under unbalanced grid voltage, and combines the grid fault response threshold to judge whether the energy storage converter needs to switch to the fault mode.

[0137] The positive and negative sequence component adjustment scheme determination module is used to monitor the grid voltage under unbalanced grid voltage in the fault mode, obtain the amplitude and phase of the grid voltage, convert the three-phase voltage signal into a DC component using synchronous coordinate transformation, use positive and negative sequence component extraction technology to separate the positive and negative sequence components, and determine the positive and negative sequence component adjustment scheme.

[0138] The above content is only an example and illustration of the structure of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them. As long as they do not deviate from the structure of the invention or exceed the scope defined by this claims, they should fall within the protection scope of the present invention.

Claims

1. A control method for an energy storage converter under an unbalanced grid voltage, characterized in that: The following steps are involved: Based on the power grid monitoring cycle stored in the database, the power grid stability characteristics under the unbalanced power grid voltage are analyzed to obtain the power grid stability characteristic determination factor; Based on the grid energy storage device status data and the grid stability characteristic determination factor, the grid energy storage device status under the unbalanced grid voltage is analyzed to obtain the energy storage converter control determination factor. According to the energy storage converter control determination factor, it is determined whether the energy storage converter needs to be controlled and the grid fault response threshold is determined: If the energy storage converter does not need to be controlled, it will enter the next cycle of grid monitoring; If the energy storage converter needs to be controlled, the grid fault characteristics under the unbalanced grid voltage are analyzed, and combined with the grid fault response threshold, it is determined whether the energy storage converter needs to be switched to the fault mode; In fault mode, the grid voltage under unbalanced grid voltage is monitored to obtain the amplitude and phase of the grid voltage. The three-phase voltage signal is converted into a DC component using synchronous coordinate transformation. The positive and negative sequence component extraction technology is used to separate the positive and negative sequence components from the DC component, and the positive and negative sequence component regulation schemes are determined. The specific analysis process of judging whether the energy storage converter needs to be controlled and determining the power grid fault response threshold according to the energy storage converter control determination factor is as follows: comparing the energy storage converter control determination factor with the energy storage converter control determination threshold stored in the database; If the energy storage converter control determination factor is not lower than the energy storage converter control determination threshold, the energy storage converter does not need to be controlled and enters the next cycle of grid monitoring; If the energy storage converter control determination factor is lower than the energy storage converter control determination threshold, the energy storage converter needs to be controlled, and the energy storage converter control determination factor is stored as a designated tag. The designated tag is compared one by one with each set tag stored in the database to determine the set tag that is the same as the designated tag, and the corresponding power grid fault response threshold stored in the database is obtained.

2. The control method of the energy storage converter under unbalanced grid voltage according to claim 1, characterized in that: The grid stability characteristics under the unbalanced grid voltage are analyzed to obtain the grid stability characteristics determination factor. The specific analysis process is as follows: Obtaining grid stability characteristic data, the grid stability characteristic data specifically includes grid voltage imbalance, grid voltage drop event frequency, and grid voltage fluctuation frequency; Based on the acquired grid stability characteristic data, a grid stability characteristic determination factor is obtained through comprehensive analysis. The grid stability characteristic determination factor serves as an analysis basis for judging whether the energy storage converter needs to be controlled and determining the grid fault response threshold.

3. The control method of the energy storage converter under unbalanced grid voltage according to claim 1, characterized in that: The state of the grid energy storage device under the unbalanced grid voltage is analyzed based on the grid energy storage device state data and the grid stability characteristic determination factor to obtain the energy storage converter control determination factor, specifically including: Obtaining grid energy storage equipment status data, which specifically includes the ratio of battery capacity to rated capacity, the cumulative number of battery charge and discharge cycles, and the output power factor of the energy storage converter; Based on the acquisition of grid energy storage equipment status data and combined with the grid stability characteristic determination factor, a comprehensive analysis is conducted to obtain the energy storage converter control determination factor, which serves as the analysis basis for determining whether the energy storage converter needs to be controlled and determining the grid fault response threshold.

4. The control method of the energy storage converter under unbalanced grid voltage according to claim 1, characterized in that: The specific analysis process of the energy storage converter control determination factor is as follows: ； In the formula, is the energy storage converter control decision factor, is the power grid stability characteristic determination factor, is the ratio of battery capacity to rated capacity, The cumulative number of battery charge and discharge cycles. is the output power factor of the energy storage converter, For setting The compensation factor, For setting The compensation factor, For setting compensation factor.

5. The control method of the energy storage converter under unbalanced grid voltage according to claim 1, characterized in that: The grid fault characteristics under unbalanced grid voltage are analyzed. The specific analysis process is as follows: Obtaining grid fault characteristic data, which specifically includes grid voltage drop duration, grid harmonic total distortion rate, and grid voltage surge value to rated voltage ratio; Based on the acquired grid fault characteristic data, a grid fault response factor is obtained through comprehensive analysis. The grid fault response factor is used as an analysis basis for determining whether the energy storage converter needs to switch to a fault mode.

6. The control method of the energy storage converter under unbalanced grid voltage according to claim 5 is characterized in that: The grid fault response threshold is combined to determine whether the energy storage converter needs to switch to the fault mode. The specific analysis process is as follows: comparing the power grid fault response factor with a power grid fault response threshold; If the grid fault response factor is not lower than the grid fault response threshold, the energy storage converter corresponding to the grid fault response factor does not need to switch to the fault mode; If the grid fault response factor is lower than the grid fault response threshold, the energy storage converter corresponding to the grid fault response factor needs to switch to the fault mode.

7. The control method of the energy storage converter under unbalanced grid voltage according to claim 1, characterized in that: The amplitude and phase of the grid voltage are obtained, and the three-phase voltage signal is converted into a DC component using synchronous coordinate transformation. The specific analysis process is as follows: Collect the three-phase voltage signal of the power grid and obtain the instantaneous amplitude of the three-phase voltage and grid phase , Represents the instantaneous value of phase A voltage, represents the instantaneous value of phase B voltage, Represents the instantaneous value of phase C voltage, and the three-phase balance condition is: ; The three-phase voltage signal is transformed using Clarke transform and Park transform. Transform to the dq rotating coordinate system: Clarke transformation converts three-phase voltage signals into stationary Coordinate system; ； ； for The shaft voltage component, for Shaft voltage component; The Park transformation The voltage components in the coordinate system are converted to synchronously rotating Rotate the coordinate system; ； ； for The shaft voltage component, for Shaft voltage component; exist In the rotating coordinate system, the grid voltage signal is regarded as a DC component. Under balanced conditions and Shows a constant value.

8. The control method of the energy storage converter under unbalanced grid voltage according to claim 7 is characterized in that: The positive and negative sequence components are separated by using the positive and negative sequence component extraction technology, and the positive and negative sequence component adjustment schemes are determined. The specific analysis process is as follows: exist In the rotating coordinate system, based on the low-pass filter and Perform low-pass filtering to extract the positive-sequence d-axis voltage component , positive sequence q-axis voltage component ; Will The rotating coordinate system is converted to the inverse synchronous rotating coordinate system, that is, based on the rotation frequency −𝜔 of the negative sequence component, the low-pass filter is used to transform the inverse synchronous rotating coordinate system and Perform low-pass filtering to extract the negative-sequence d-axis voltage component and the negative sequence q-axis voltage component ; The process of determining the positive sequence component regulation scheme is: Active power control: Get the active power reference value stored in the database ; ； is the positive sequence d-axis current reference value; Use the PI controller to convert the current d-axis current and Compare and generate d-axis current control signal To regulate active power output; Reactive power control: Get reactive power reference value stored in database ; ； is the positive sequence q-axis current reference value; Use the PI controller to convert the current q-axis current and Compare and generate q-axis current control signal To regulate reactive power output; The process of determining the negative sequence component regulation scheme is: Negative sequence current compensation: To balance the grid current, the negative sequence d-axis current component and the q-axis current component Set as a goal; Use the PI controller to convert the current negative sequence d-axis current component and the negative sequence q-axis current component Compared with the target, the control output negative sequence d-axis current control signal is obtained and negative sequence q-axis current control signal , generate compensation current and suppress negative sequence current; Negative sequence voltage compensation: To reduce the impact of negative sequence voltage, the negative sequence d-axis voltage component and the q-axis voltage component Set as a goal; Use the PI controller to convert the current negative sequence d-axis voltage component and the negative sequence q-axis voltage component Compared with the target, the control output negative sequence d-axis voltage control signal is obtained and negative sequence q-axis voltage control signal , adjust the output voltage to achieve voltage balance.

9. A control system for an energy storage converter under an unbalanced grid voltage, applied to a control method for an energy storage converter under an unbalanced grid voltage as claimed in any one of claims 1 to 8, characterized in that: It includes a stability characteristic determination factor acquisition module, an energy storage converter control determination module and a positive and negative sequence component adjustment scheme determination module, wherein: The stability characteristic determination factor acquisition module is used to analyze the grid stability characteristics under the unbalanced grid voltage based on the grid monitoring cycle stored in the database to obtain the grid stability characteristic determination factor; The energy storage converter control judgment module is used to analyze the state of the grid energy storage device under the unbalanced grid voltage based on the grid energy storage device state data and the grid stability characteristic judgment factor, obtain the energy storage converter control judgment factor, and judge whether the energy storage converter needs to be controlled and determine the grid fault response threshold according to the energy storage converter control judgment factor: If the energy storage converter does not need to be controlled, it will enter the next cycle of grid monitoring; If the energy storage converter needs to be controlled, the grid fault characteristics under the unbalanced grid voltage are analyzed, and combined with the grid fault response threshold, it is determined whether the energy storage converter needs to be switched to the fault mode; The positive and negative sequence component regulation scheme determination module is used to monitor the grid voltage under the unbalanced grid voltage in the fault mode, obtain the amplitude and phase of the grid voltage, convert the three-phase voltage signal into a DC component using a synchronous coordinate transformation, separate the positive sequence and negative sequence components from the DC component using a positive and negative sequence component extraction technology, and determine the positive sequence and negative sequence component regulation schemes; The specific analysis process of judging whether the energy storage converter needs to be controlled and determining the power grid fault response threshold according to the energy storage converter control determination factor is as follows: comparing the energy storage converter control determination factor with the energy storage converter control determination threshold stored in the database; If the energy storage converter control determination factor is not lower than the energy storage converter control determination threshold, the energy storage converter does not need to be controlled and enters the next cycle of grid monitoring; If the energy storage converter control determination factor is lower than the energy storage converter control determination threshold, the energy storage converter needs to be controlled, and the energy storage converter control determination factor is stored as a designated tag. The designated tag is compared one by one with each set tag stored in the database to determine the set tag that is the same as the designated tag, and the corresponding power grid fault response threshold stored in the database is obtained.

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