Energy storage device droop control method and system considering power grid stability

Abstract

The invention discloses an energy storage device droop control method and system considering power grid stability, and belongs to the technical field of energy storage devices, and the method comprises the steps: collecting power grid state information, and obtaining the current power grid operation state data; constructing a power grid stability evaluation function based on the scoring function of the power grid operation state data; dynamically adjusting a droop coefficient through a mapping function based on a power grid stability evaluation function; and calculating the power regulation quantity of the energy storage device through the droop coefficient to obtain the output power of the energy storage device so as to regulate the frequency of the power grid, and carrying out monitoring and feedback. According to the method, the power regulation capability can be enhanced when the power grid disturbance is aggravated, and the flexible response is kept when the power grid operates stably, so that the frequency modulation precision and stability of the energy storage system are effectively improved, the problems of power jump, power grid system overregulation or energy storage overload are effectively inhibited, and the stability of the control process and the equipment safety are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage devices, and in particular to a droop control method and system for an energy storage device taking grid stability into consideration. Background Art

[0002] With the large-scale integration of renewable energy, the inertia level of the power system continues to decline, frequency fluctuations intensify, and grid operational stability faces severe challenges. Energy storage systems, with their rapid response capabilities, are playing an increasingly important role in grid frequency regulation. Droop control strategies are widely used in the grid-connected control of energy storage systems. The basic idea is to simulate the frequency-power regulation characteristics of traditional synchronous generators. By setting a droop coefficient, the energy storage power output is automatically adjusted according to frequency deviations, achieving dynamic stability of the system frequency.

[0003] However, existing droop control methods typically employ fixed coefficient designs, ignoring the dynamic changes in grid conditions. This results in excessively high regulation rigidity and the susceptibility to power jumps in strong grids, while insufficient regulation capability in weak grids makes it difficult to quickly respond to system disturbances. Furthermore, traditional droop strategies often rely on a single frequency offset metric and lack the ability to comprehensively perceive multi-dimensional information such as voltage fluctuations, frequency change rate, and short-circuit ratio. This makes it difficult to accurately assess grid stability, leading to mismatched energy storage response strategies and potentially even triggering new system disturbances. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to solve the problem that traditional droop strategies mostly rely on a single frequency offset indicator, making it difficult to accurately assess the stability of the power grid, resulting in mismatched energy storage response strategies and even potentially triggering new system disturbances.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solutions: a droop control method for an energy storage device taking into account grid stability, comprising: collecting grid status information to obtain current grid operating status data; constructing a grid stability evaluation function based on a scoring function of the grid operating status data; dynamically adjusting the droop coefficient through a mapping function based on the grid stability evaluation function; and calculating the power regulation amount of the energy storage device through the droop coefficient to obtain the output power of the energy storage device, thereby adjusting the grid frequency, and performing monitoring and feedback.

[0007] As a preferred solution of the energy storage device droop control method considering grid stability described in the present invention, wherein: the current grid operation status data includes frequency offset, frequency change rate, voltage offset and short circuit ratio; the frequency offset is obtained by comparing the current frequency value with the grid system reference frequency; a fixed time interval is defined as the frequency change rate calculation window, and the frequency offset is calculated at time intervals. At this moment, the frequency change rate value is calculated as:

[0008] in, for The frequency change rate at time, for The frequency offset at time , for The frequency offset at time , The time interval is set; the original RoCoF sequence is subjected to three-point median filtering; the three-phase bus voltage is obtained to obtain the effective value of the phase voltage, the real-time effective value of the voltage is compared with the preset rated voltage to obtain the initial voltage offset, and a first-order low-pass filter is introduced into the initial voltage offset to obtain the filtered voltage offset; the short-circuit ratio is the ratio of the short-circuit capacity of the grid-connected point to the rated capacity of the energy storage device.

[0009] As a preferred embodiment of the droop control method for an energy storage device considering grid stability described in the present invention, the scoring function based on the grid operation status data is used to construct a grid stability evaluation function, including forming the acquired current grid operation status data into a vector form, which is expressed as:

[0010] in, is the current power grid operation status data vector, for The frequency change rate after the three-point median filtering process, for The voltage offset after filtering at the moment, for moment short-circuit ratio; construct a state quantity piecewise scoring function based on the current power grid operation status data; and construct a power grid stability evaluation function by weighted summing the scoring results of each current power grid operation status data.

[0011] As a preferred solution of the energy storage device droop control method considering grid stability described in the present invention, the state quantity piecewise scoring function is expressed as:

[0012]

[0013] in, is the first vector of the current power grid operation status data. indicators, is the first vector of the current power grid operation status data. The allowable value of each indicator when the power grid is in a stable state. is the first vector of the current power grid operation status data. The critical value of the indicator reaching the unstable state is obtained; the grid stability evaluation function constructed by weighted summation is expressed as:

[0014]

[0015] in, is the comprehensive stability evaluation function, is the value of the scoring function for the frequency offset, is the weight of the frequency offset, is the value of the scoring function for the frequency change rate, is the weight of the frequency change rate, is the value of the scoring function for the voltage offset, is the weight of the voltage offset, is the value of the scoring function of the short-circuit ratio, is the weight of the short-circuit ratio; the entropy weight method is used to allocate the weight.

[0016] As a preferred embodiment of the droop control method for an energy storage device considering grid stability described in the present invention, the method dynamically adjusts the droop coefficient through a mapping function based on a grid stability evaluation function, including calculating the droop coefficient based on the grid stability evaluation function, expressed as:

[0017] in, is the adjusted droop coefficient, is the initial droop coefficient, is the mapping function from the stability function value to the adjustment coefficient.

[0018] This preferred solution introduces a dynamic mapping function with the grid stability assessment function as the independent variable, enabling adaptive adjustment of the droop coefficient under different grid stability states. When system stability is poor, the response strength is automatically increased, improving the frequency regulation capability of the energy storage device. When the grid is stable, the original coefficient is maintained to avoid over-response, thus achieving dynamic matching of different operating conditions and enhancing the overall system's regulatory adaptability and frequency control accuracy.

[0019] As a preferred embodiment of the droop control method for an energy storage device considering grid stability according to the present invention, the mapping function from the stability function value to the adjustment coefficient includes using a linear mapping function to adjust the droop coefficient, which is expressed as:

[0020] Then the frequency-power response relationship droop control is expressed as:

[0021] in, is the adjustment coefficient, is the change in active power that the energy storage device should output, is the frequency offset.

[0022] As a preferred solution of the droop control method of an energy storage device considering grid stability described in the present invention, the output power of the energy storage device is expressed as:

[0023] in, is the energy storage output power, is the initial power output of the energy storage device; output power judgment is performed, if the output power Exceeding the maximum power limit , the energy storage device needs to enter the power limiting protection state and limit the power to , and keep Output until the grid frequency changes and stabilizes to avoid over-regulation causing grid instability and energy storage device overload; if the output power Less than the preset minimum power limit , then the power output should be increased to , and keep Output, to ensure that the grid frequency does not drop any more, to ensure that the frequency stability is not excessively reduced, to avoid the frequency continuing to drop and causing system instability; if the output power If the power is within the effective range, the normal adjustment should continue and the appropriate response should be made according to the change of the grid frequency; the power change rate should be judged. If the power change rate of the energy storage device exceeds the set maximum rate, , it indicates that the adjustment is too fast and the adjustment speed needs to be limited to smoothly control the power change and limit the power adjustment rate to avoid grid oscillation. If the power change rate is within a reasonable range, normal adjustment will continue without additional restrictions.

[0024] This preferred solution effectively prevents system shocks caused by power overshoot or excessive rate by constructing a dynamic limiting strategy. Furthermore, based on the grid frequency recovery situation, it sets power adjustment limits and fallback strategies to ensure stable, continuous, and controllable energy storage output, thereby enhancing the safety and engineering feasibility of the system in actual operation.

[0025] The present invention provides a droop control method system for an energy storage device taking grid stability into consideration.

[0026] To solve the above technical problems, the present invention provides the following technical solutions: a droop control method system for an energy storage device taking into account grid stability, comprising: a data acquisition module, a grid stability evaluation function construction module, a droop coefficient adjustment module and a monitoring feedback module; the data acquisition module is used to collect grid status information and obtain current grid operation status data; the grid stability evaluation function construction module is used to construct a grid stability evaluation function based on a scoring function of the grid operation status data; the droop coefficient adjustment module is used to dynamically adjust the droop coefficient through a mapping function based on the grid stability evaluation function; the monitoring feedback module is used to calculate the power regulation amount of the energy storage device through the droop coefficient, obtain the output power of the energy storage device, so as to adjust the grid frequency, and perform monitoring and feedback.

[0027] The present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of the energy storage device droop control method considering grid stability are implemented.

[0028] The present invention provides a computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the steps of the energy storage device droop control method considering grid stability are implemented.

[0029] Beneficial effects of the present invention: The present invention constructs a unified grid stability evaluation function by integrating multi-dimensional grid state parameters such as frequency offset, frequency change rate, voltage offset and short-circuit ratio, and dynamically adjusts the droop control coefficient of the energy storage device accordingly, thereby realizing real-time identification and differentiated response to the grid stability state. This mechanism can enhance the power regulation capability when the grid disturbance intensifies and maintain a flexible response when the grid operates smoothly, thereby effectively improving the frequency regulation accuracy and stability of the energy storage system. In addition, the present invention adopts the entropy weight method to realize the adaptive calculation of the weights of each state indicator, avoiding the errors caused by subjective weighting, and enhancing the objectivity and identification ability of the evaluation results. By setting the upper and lower limits of power output and the maximum power change rate, dynamic constraints on the power regulation process are realized, effectively suppressing power jumps, grid system overregulation or energy storage overload problems, and ensuring the stability of the control process and equipment safety. Overall, the present invention improves the response flexibility and engineering feasibility of the energy storage system in a complex grid operating environment, and has strong practical value and promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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 work.

[0031] Figure 1 An overall flow chart of a droop control method for an energy storage device considering grid stability is provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0032] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0033] Example 1, reference Figure 1 , is an embodiment of the present invention, which provides a droop control method for an energy storage device considering grid stability, comprising: S1. Collect grid status information and obtain current grid operation status data.

[0034] S2. Construct a grid stability evaluation function based on the scoring function of the grid operation status data.

[0035] S3. Dynamically adjust the droop coefficient through a mapping function based on the grid stability evaluation function.

[0036] S4. Calculate the power regulation amount of the energy storage device through the droop coefficient to obtain the output power of the energy storage device to adjust the grid frequency and perform monitoring and feedback.

[0037] It should be noted that in current power systems, grid frequency is affected by factors such as renewable energy fluctuations and a weakened grid structure, resulting in frequent offset fluctuations. Traditional droop control methods employ fixed coefficients, which are insufficient in weak grid conditions and can cause over-response in strong grid conditions, impacting frequency stability. Furthermore, the responsiveness of energy storage devices is limited by the degree of compatibility between their power range and the control strategy. Therefore, to address issues such as insufficient grid state awareness, strong response rigidity, and mismatched regulation capabilities, this embodiment establishes a complete grid state awareness and response regulation mechanism through steps S1 through S5.

[0038] This mechanism autonomously assesses grid stability based on real-time grid status data and dynamically adjusts the energy storage system's response coefficient, enabling precise and appropriate frequency regulation under varying operating conditions. In particular, the system proactively enhances its response during periods of severe grid disturbances or instability. When the grid is stable, it maintains flexible output to avoid overregulation, significantly improving the adaptability and control performance of energy storage devices during grid-connected operation.

[0039] Embodiment 2 is an embodiment of the present invention, and provides a droop control method for an energy storage device taking into account grid stability based on the previous embodiment, including: In step S1, the grid status information is collected to obtain the current grid operation status data.

[0040] The grid status information includes frequency offset, frequency change rate, voltage offset and short circuit ratio.

[0041] Frequency offset refers to the instantaneous offset of the actual grid operating frequency relative to the nominal power frequency. The current frequency value is obtained in real time through a digital frequency measurement unit (such as a PLL phase-locked loop or DFT frequency tracker) configured at the energy storage device's grid connection point.

[0042] Compared with the grid system reference frequency (such as 50Hz), the frequency offset is obtained, which is expressed as:

[0043] in, is the frequency value at time t, is the reference frequency, is the frequency offset at time t.

[0044] The frequency value sampling period is set to 10ms to 20ms, and the sampling frequency is not less than 50Hz to ensure that transient changes at high RoCoF moments are captured.

[0045] Define a fixed time interval as the rate of change of frequency (ROCOF) calculation window. At this moment, the frequency change rate value is calculated as:

[0046] in, for The frequency change rate at time, for The frequency offset at time , is the time interval.

[0047] To avoid RoCoF anomalies caused by harmonic noise, communication jitter, or sampling transients, the original RoCoF sequence is subjected to a three-point median filter, which is expressed as follows:

[0048] in, for The frequency change rate after the three-point median filtering process, for The frequency change rate at time, for The frequency change rate at time, To perform a median filtering operation on the three input values, the value in the middle of the three is taken as the smoothing value of the current RoCoF to suppress outlier fluctuations.

[0049] Voltage offset: The energy storage device is also equipped with a voltage sampling device at the grid connection point, which uses a voltage transformer (VT) to convert the high-voltage signal of the grid to a measurable range for the control system. The voltage signal is sampled by the analog-to-digital conversion (ADC) module. The sampling frequency is recommended to be no less than 5kHz to ensure that the voltage fluctuation details are captured. The controller obtains the instantaneous sampling value 、 、 , corresponding to the three-phase bus voltage.

[0050] Using the phase A voltage as a representative, perform the RMS calculation on the sampled signal within the sliding window to obtain the effective value of the phase voltage:

[0051] in, is the effective value of the phase voltage, is the number of sampling points in the sliding window, The first phase voltage The sampling value of the sampling point, For the sampling points.

[0052] Compare the real-time voltage RMS value with the preset rated voltage to obtain the initial voltage offset, which is expressed as:

[0053] in, for The initial voltage offset at time , for The effective value of the phase voltage at the moment, is the preset rated voltage.

[0054] To enhance the anti-interference performance, Introducing a first-order low-pass filter, the filter function is as follows:

[0055] in, for The voltage offset after filtering at the moment, for The voltage offset after filtering at the moment, is the filter coefficient, which is automatically adjusted according to the disturbance intensity or signal noise value, during normal operation, the noise is small, set Small (mainly stable); when disturbance occurs, the change is drastic, Improve (fast track); set The range is 0.1 to 0.3.

[0056] The noise level can be estimated by the standard deviation σ Adjust, define the maximum and minimum standard deviation thresholds and the corresponding filter coefficient range, expressed as:

[0057] in, for The moment filter coefficient, is the minimum filter coefficient, is the maximum filter coefficient, is the voltage standard deviation, is the minimum standard deviation threshold, is the maximum standard deviation threshold.

[0058] Short-circuit ratio (SCR) is used to estimate the short-circuit ratio (SCR) at the energy storage device's grid connection point, serving as a key structural indicator for determining the system's strong or weak grid characteristics. SCR is the ratio of the short-circuit capacity at the grid connection point to the rated capacity of the energy storage device. A smaller value indicates a weaker grid. The short-circuit ratio can be calculated as:

[0059] in, for Moment short circuit ratio; for The short-circuit capacity of the grid-connected point at any given moment, that is, the maximum apparent power that the system can provide when a short circuit occurs at that point; is the rated capacity of the connected energy storage device.

[0060] The short-circuit capacity of the grid connection point can be calculated as follows:

[0061] in, is the equivalent positive sequence impedance from the grid connection point back to the substation.

[0062] Furthermore, in step S2, a grid stability evaluation function is constructed based on a scoring function of the grid operation status data.

[0063] This step aims to construct a unified grid stability evaluation function based on the multi-dimensional grid state parameters collected in step S1, which is used to quantify the stability of the current grid operation and serve as the driving input for the subsequent droop control parameter adjustment.

[0064] First, the current grid operation status data obtained by S1 is formed into a vector form, which is expressed as:

[0065] in, is the current power grid operation status data vector.

[0066] The scoring interval of the scoring function consists of two thresholds and Sure, Indicates the allowable value of the operating status data when the power grid is in a stable state. Indicates that the critical value of instability or strong response is reached. The scoring function of each operating state data is in the interval The score decreases linearly within the interval, and the score outside the interval is 0, indicating that the system operation status is unacceptable.

[0067] The constructed state quantity piecewise scoring function is expressed as:

[0068]

[0069] in, is the first vector of the current power grid operation status data. indicators, is the first vector of the current power grid operation status data. The allowable value of each indicator when the power grid is in a stable state. is the first vector of the current power grid operation status data. The critical value of an indicator reaching an unstable state. The indicator refers to the operating status data.

[0070] The allowable values ​​and critical values ​​of indicators are set according to relevant industry standards and the stability requirements of energy storage devices.

[0071] The grid stability evaluation function is constructed by weighted summing the scoring results, which can be expressed as:

[0072]

[0073] in, is the grid stability evaluation function, is the value of the scoring function for the frequency offset, is the weight of the frequency offset, is the value of the scoring function for the frequency change rate, is the weight of the frequency change rate, is the value of the scoring function for the voltage offset, is the weight of the voltage offset, is the value of the scoring function of the short-circuit ratio, is the weight of the short circuit ratio.

[0074] 、 、 and It is obtained based on the piecewise scoring function of the state quantity.

[0075] Furthermore, the entropy weight method is used to assign weights to various power grid indicators (such as frequency offset, RoCoF, voltage offset, and short-circuit ratio). By evaluating the discrete degree of different scoring indicators under multiple disturbance conditions, the contribution of each indicator to the system identification capability is quantified, and thus each indicator is assigned a corresponding weight value.

[0076] The entropy weight method is based on the information entropy theory, which believes that the greater the variability of an indicator value in the sample, the more information it provides and the greater its weight should be, and vice versa.

[0077] Set m typical disturbance conditions (such as different load mutations, fault locations, power supply connections, etc.), and calculate the four scoring function values ​​defined in the present invention for each condition. That is, the value of the scoring function of the frequency offset, That is, the value of the scoring function of the frequency change rate, That is, the value of the scoring function of the voltage offset, The value of the scoring function for the short-circuit ratio.

[0078] The perturbation score matrix is ​​constructed as:

[0079] in, , indicating the In the disturbance condition The value of the scoring function of an indicator; Perform column normalization on the perturbation score matrix, and for each column (i.e. the scoring function of each indicator) is normalized and expressed as:

[0080] in, After normalization, In the disturbance condition The value of the scoring function of an indicator.

[0081] The normalized weight matrix is ​​expressed as:

[0082] in, is the normalized weight matrix.

[0083] , and for each column satisfy .

[0084] The information entropy of each column scoring function is calculated as:

[0085]

[0086] in, For the The information entropy of the scoring function of the indicator, is the entropy normalization constant.

[0087] like If it is 0, then define Set to 0 to avoid numerical anomalies.

[0088] , reflecting the The information balance of the scoring function of each indicator under all disturbance conditions. The more stable the indicator (the smaller the difference), the higher the entropy; the more sensitive the indicator (the larger the difference), the lower the entropy.

[0089] The information utility value is calculated based on the information entropy and is expressed as:

[0090] in, For the The information utility of the scoring function of each indicator, that is, its identification ability in the overall evaluation.

[0091] The weights of each scoring function calculated according to the utility value are expressed as:

[0092] in, For the The weight of an indicator.

[0093] And the normalization conditions are met:

[0094] The calculated weights will be used to construct a comprehensive stability function, which serves as the key input to the droop parameter adjustment module in the energy storage control system. This function drives the dynamic update of the droop coefficient and enables the energy storage device to respond and adjust in real time to changes in the grid state.

[0095] In step S3, the droop coefficient is dynamically adjusted through a mapping function based on the grid stability evaluation function.

[0096] In the prior art, droop control is widely used in the grid-connected control of energy storage devices. Its basic idea is to simulate the frequency-power response relationship of the synchronous generator and output the corresponding active power adjustment value according to the grid frequency offset, which is expressed as:

[0097] in, is the change in active power that the energy storage device should output, is the frequency offset, is the droop coefficient, which indicates the power regulation capability corresponding to unit frequency offset.

[0098] In the embodiment of the present application, in order to solve the problems of the existing droop control method such as response rigidity, regulation jump, lack of grid stability perception, etc., a method based on stability evaluation function is proposed. The droop coefficient self-tuning control mechanism.

[0099] The present invention uses the droop coefficient Changed to be based on the grid stability evaluation function Dynamic amount , expressed as:

[0100] in, is the adjusted droop coefficient, is the initial droop coefficient, which is set according to the rated capacity of the energy storage device and the frequency regulation margin; is the mapping function from the stability function value to the adjustment coefficient. When it approaches 1 (grid stability), Also tends to 1, that is, maintain normal response; when When it approaches 0 (the power grid is unstable), If it is greater than 0, the response strength will be automatically increased.

[0101] The design goal of the mapping function is to maintain the original droop coefficient when the grid state is stable; when the grid state is unstable, the droop coefficient is increased through the mapping function to enhance the regulation capability and avoid excessive response leading to system instability.

[0102] In this application, a linear mapping function is used to adjust the droop coefficient. , the mapping function is as follows:

[0103] in, The adjustment coefficient is used to control the increase of the droop coefficient when the power grid is unstable. It is set according to the specific characteristics of the power grid, the response capability of the energy storage device and engineering experience. Usually a smaller value is selected. When the power grid is relatively stable, the influence of the adjustment coefficient is small. Keep in Nearby; when the power grid is relatively unstable, the influence of the regulation coefficient increases, It will be significantly improved to enhance the frequency response of the energy storage device.

[0104] According to the grid stability assessment results and the regulation coefficient, the droop coefficient is dynamically adjusted through the mapping function as follows:

[0105] Then the frequency-power response relationship droop control is expressed as:

[0106] In step S4, the power regulation amount of the energy storage device is calculated by the droop coefficient to obtain the output power of the energy storage device to adjust the grid frequency and perform monitoring and feedback.

[0107] The energy storage output power is expressed as:

[0108] in, is the energy storage output power, The initial power output of the energy storage device, usually the normal operating power of the device when it is not adjusted.

[0109] In order to prevent over-regulation from causing overload of the energy storage device, the maximum and minimum power limits are set as follows:

[0110] in, The minimum output power of the energy storage device (for example, when the grid frequency is too high, the energy storage device should absorb power, usually set to a negative value); is the maximum output power of the energy storage device (i.e., when the frequency is too low, the energy storage device should output power to avoid excessive response). Set it according to the rated capacity and maximum discharge capacity of the energy storage device, and select the smaller value between the rated capacity and maximum discharge capacity of the energy storage device as ; Set it according to the rated capacity and minimum discharge capacity of the energy storage device, and choose the larger value between the negative value of the rated capacity and the minimum discharge capacity as .

[0111] The output power change rate of the energy storage device also needs to be limited to prevent excessive power changes from causing grid oscillations:

[0112] in, For energy storage devices The power change at each moment, for The energy storage output power at the moment, for Energy storage output power at all times, is the time interval of power change, is the power change rate, The maximum power response rate limit indicates the maximum power change rate of the energy storage device per unit time. It prevents the energy storage device from responding too quickly during frequency modulation and thus impacting the power grid. It is determined based on the maximum charge and discharge power and time constant of the energy storage device.

[0113] If the output power Exceeded the maximum power limit , the energy storage device needs to enter the power limiting protection state and limit the power to , and maintain this output until the grid frequency changes and stabilizes, to avoid over-regulation causing grid instability or energy storage device overload.

[0114] If the output power Less than the preset minimum power limit , then the power output should be increased to , and maintain this output to ensure that the grid frequency does not drop any further, so as to ensure that the frequency stability is not excessively reduced, and avoid the frequency continuing to drop and causing system instability.

[0115] If the output power If the frequency is within the valid range, normal regulation should continue and appropriate response should be made according to the changes in grid frequency.

[0116] After the energy storage device passes the power assessment, if there is still a deviation between the current power and the target power, a gradual adjustment strategy is implemented based on the grid frequency recovery. During the recovery process, the adjustment amplitude is gradually reduced: If the grid frequency is close to the target range, the power adjustment amplitude is gradually reduced to avoid the negative impact of frequent power fluctuations on the grid. If the grid frequency fluctuates significantly (for example, the frequency deviation is greater than ±0.2 Hz), the feedback gain is increased to provide a stronger power regulation response to help the grid quickly restore stability.

[0117] Perform power change rate judgment. If the power change rate of the energy storage device exceeds the set maximum rate, , it indicates that the regulation is too fast, which may cause grid oscillation or overshoot. Therefore, the regulation speed needs to be limited to smoothly control power changes and limit the power regulation rate to avoid grid oscillation.

[0118] If the power change rate is within a reasonable range, normal regulation will continue without additional restrictions.

[0119] Example 3, an embodiment of the present invention, provides a droop control method system for an energy storage device considering grid stability, including a data acquisition module, a grid stability evaluation function construction module, a droop coefficient adjustment module and a monitoring feedback module.

[0120] The data acquisition module is used to collect grid status information and obtain current grid operation status data.

[0121] The power grid stability evaluation function construction module is used to construct a power grid stability evaluation function based on a scoring function of power grid operation status data.

[0122] The droop coefficient adjustment module is used to dynamically adjust the droop coefficient through a mapping function based on the grid stability evaluation function.

[0123] The monitoring and feedback module is used to calculate the power regulation amount of the energy storage device through the droop coefficient, obtain the output power of the energy storage device, adjust the grid frequency, and perform monitoring and feedback.

[0124] This embodiment also provides an electronic device, which is applicable to a droop control method for an energy storage device considering grid stability, and includes: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute computer-executable instructions to implement a droop control method for an energy storage device considering grid stability as proposed in the above embodiment. This embodiment further provides a storage medium having a computer program stored thereon. When the program is executed by a processor, a droop control method for an energy storage device considering grid stability as proposed in the above embodiment is implemented. The storage medium proposed in this embodiment and the method for implementing a droop control method for an energy storage device considering grid stability proposed in the above embodiment belong to the same inventive concept. Technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment. Through the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented with the help of software and necessary general-purpose hardware. Of course, it can also be implemented with hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of the present invention, or the part that contributes to the existing technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory (FLASH), hard disk or optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods of various embodiments of the present invention.

[0125] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A droop control method for an energy storage device considering grid stability, characterized by: include, Collect grid status information and obtain current grid operation status data; Constructing a grid stability evaluation function based on the scoring function of grid operation status data; Dynamically adjust the droop coefficient through a mapping function based on the grid stability evaluation function; The power regulation amount of the energy storage device is calculated through the droop coefficient to obtain the output power of the energy storage device to adjust the grid frequency and perform monitoring and feedback.

2. The method for controlling droop of an energy storage device considering grid stability according to claim 1, wherein: The current grid operation status data includes frequency offset, frequency change rate, voltage offset and short circuit ratio; The frequency offset is obtained by comparing the current frequency value with the reference frequency of the power grid system; Define a fixed time interval as the frequency change rate calculation window. At this moment, the frequency change rate value is calculated as, in, for The frequency change rate at time, for The frequency offset at time , for The frequency offset at time , is the time interval; And perform three-point median filtering on the original RoCoF sequence; Obtain the three-phase bus voltage and obtain the phase voltage effective value. Compare the real-time voltage effective value with the preset rated voltage to obtain the initial voltage offset. Apply a first-order low-pass filter to the initial voltage offset to obtain the filtered voltage offset. The short-circuit ratio is the ratio of the short-circuit capacity of the grid connection point to the rated capacity of the energy storage device.

3. The method for controlling droop of an energy storage device taking into account grid stability according to claim 2, wherein: The scoring function based on the grid operation status data constructs a grid stability evaluation function, including: The current grid operation status data obtained is formed into a vector form and expressed as: in, is the current power grid operation status data vector, for The frequency change rate after the three-point median filtering process, for The voltage offset after filtering at the moment, for Moment short circuit ratio; Construct a state quantity piecewise scoring function based on the current power grid operation status data; The scoring results of each current power grid operation status data are weighted summed to construct a power grid stability evaluation function.

4. The method for controlling droop of an energy storage device taking into account grid stability according to claim 3, wherein: The state quantity piecewise scoring function is expressed as: in, is the first vector of the current power grid operation status data. indicators, is the first vector of the current power grid operation status data. The allowable value of each indicator when the power grid is in a stable state. is the first vector of the current power grid operation status data. The critical value of an indicator reaching an unstable state; The grid stability evaluation function constructed by weighted summation is expressed as: in, is the comprehensive stability evaluation function, is the value of the scoring function for the frequency offset, is the weight of the frequency offset, is the value of the scoring function for the frequency change rate, is the weight of the frequency change rate, is the value of the scoring function for the voltage offset, is the weight of the voltage offset, is the value of the scoring function of the short-circuit ratio, is the weight of the short-circuit ratio; The entropy weight method is used for weight distribution.

5. The method for controlling droop of an energy storage device taking into account grid stability according to claim 4, wherein: The method of dynamically adjusting the droop coefficient through a mapping function based on the grid stability evaluation function includes: The droop coefficient is calculated based on the grid stability evaluation function and is expressed as, in, is the adjusted droop coefficient, is the initial droop coefficient, is the mapping function from the stability function value to the adjustment coefficient.

6. The method for controlling droop of an energy storage device taking into account grid stability according to claim 5, wherein: The mapping function from the stability function value to the adjustment coefficient includes using a linear mapping function to adjust the droop coefficient, expressed as, Then the frequency-power response relationship droop control is expressed as, in, is the adjustment coefficient, is the change in active power that the energy storage device should output, is the frequency offset.

7. The method for controlling droop of an energy storage device taking into account grid stability according to claim 6, wherein: The output power of the energy storage device is expressed as, in, is the energy storage output power, is the initial power output of the energy storage device; Perform output power judgment. If the output power Exceeding the maximum power limit , the energy storage device needs to enter the power limiting protection state and limit the power to , and keep Output until the grid frequency changes and stabilizes, avoiding over-regulation causing grid instability and overload of energy storage devices; If the output power Less than the preset minimum power limit , then the power output should be increased to , and keep Output, to ensure that the grid frequency does not drop any further, to ensure that the frequency stability is not excessively reduced, and to avoid the frequency continuing to drop and causing system instability; If the output power If it is within the effective range, normal regulation should continue and appropriate response should be made according to the change of grid frequency; Perform power change rate judgment. If the power change rate of the energy storage device exceeds the set maximum rate, , it indicates that the adjustment is too fast and the adjustment speed needs to be limited to smoothly control the power change and limit the power adjustment rate to avoid grid oscillation; If the power change rate is within a reasonable range, normal regulation will continue without additional restrictions.

8. A droop control method system for an energy storage device considering grid stability, applying the droop control method for an energy storage device considering grid stability according to any one of claims 1 to 7, characterized in that: include: Data acquisition module, grid stability assessment function construction module, droop coefficient adjustment module and monitoring feedback module; The data acquisition module is used to collect power grid status information and obtain current power grid operation status data; The power grid stability evaluation function construction module is used to construct a power grid stability evaluation function based on the scoring function of the power grid operation status data; The droop coefficient adjustment module is used to dynamically adjust the droop coefficient through a mapping function based on the grid stability evaluation function; The monitoring and feedback module is used to calculate the power regulation amount of the energy storage device through the droop coefficient, obtain the output power of the energy storage device, adjust the grid frequency, and perform monitoring and feedback.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a droop control method for an energy storage device considering grid stability according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a droop control method for an energy storage device considering grid stability according to any one of claims 1 to 7 are implemented.

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