A method and system for droop control of energy storage devices considering grid stability

Abstract

This invention discloses a droop control method and system for energy storage devices that considers grid stability, belonging to the field of energy storage device technology. The method includes: collecting grid state information to obtain current grid operating state data; constructing a grid stability assessment function based on a scoring function of the grid operating state data; dynamically adjusting the droop coefficient using a mapping function based on the grid stability assessment function; calculating the power regulation of the energy storage device using the droop coefficient to obtain the output power of the energy storage device, thereby regulating the grid frequency and providing monitoring and feedback. This invention can enhance power regulation capability when grid disturbances intensify and maintain flexible response when the grid is operating smoothly, thus effectively improving the frequency regulation accuracy and stability of the energy storage system, effectively suppressing power jumps, grid system over-adjustment, or energy storage overload problems, and ensuring the smoothness of the control process and equipment safety.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and more specifically to a droop control method and system for energy storage devices that takes into account grid stability. Background Technology

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

[0003] However, existing droop control methods typically employ fixed-coefficient designs, neglecting the dynamic changes in grid conditions. This leads to excessively high regulation rigidity and susceptibility to power surges under strong grid conditions, while insufficient regulation capability under weak grid conditions makes it difficult to respond quickly to system disturbances. Furthermore, traditional droop strategies often rely on a single frequency offset indicator, lacking the comprehensive perception capability of multi-dimensional information such as voltage fluctuations, frequency change rate, and short-circuit ratio. This makes it difficult to accurately assess the grid stability state, resulting in mismatched energy storage response strategies and potentially 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 this invention is: how to solve the problem that traditional droop strategies rely on a single frequency offset index, which makes it difficult to accurately assess the grid stability state, leading to mismatch in energy storage response strategies and even potentially causing new system disturbances.

[0006] To address the aforementioned technical problems, this invention provides the following technical solution: a droop control method for an energy storage device considering grid stability, comprising: collecting grid state information to obtain current grid operating state data; constructing a grid stability assessment function based on a scoring function of the grid operating state data; dynamically adjusting the droop coefficient based on the grid stability assessment function through a mapping function; calculating the power regulation amount of the energy storage device using 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 embodiment of the droop control method for energy storage devices considering grid stability described in this invention, the current grid operating 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. The value of the rate of change of frequency at time t is calculated as follows:

[0008]

[0009] in, for Rate of change of frequency at time, for Frequency offset at time, for Frequency offset at time, The time interval is defined as follows: the original RoCoF sequence is subjected to three-point median filtering; the three-phase bus voltage is obtained, the effective value of the phase voltage is obtained, 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 at the grid connection point to the rated capacity of the energy storage device.

[0010] As a preferred embodiment of the energy storage device droop control method considering grid stability described in this invention, the grid stability evaluation function is constructed based on the scoring function of grid operating status data, including constructing the acquired current grid operating status data into a vector form, as follows:

[0011]

[0012] in, This is a data vector representing the current power grid operating status. for The rate of change of frequency after median filtering at three points at time t. for Voltage offset after filtering at any time. for Short-circuit ratio at any time; construct a segmented scoring function for state variables based on current power grid operating status data; construct a power grid stability assessment function by weighted summation of the scoring results of various current power grid operating status data.

[0013] As a preferred embodiment of the energy storage device droop control method considering grid stability described in this invention, the state variable piecewise scoring function is expressed as:

[0014]

[0015]

[0016] in, The first data vector representing the current power grid operating status One indicator, The first data vector representing the current power grid operating status The permissible values ​​of each indicator when the power grid is in a stable state. The first data vector representing the current power grid operating status The critical values ​​of each indicator that lead to an unstable state; the power grid stability assessment function constructed by weighted summation is expressed as:

[0017]

[0018]

[0019] in, For the comprehensive stability evaluation function, The value of the scoring function for the frequency offset. As the weight of the frequency offset, The value of the scoring function for the rate of change of frequency. As the weight of the rate of change of frequency, The value of the scoring function for voltage offset. As the weight of voltage offset, The value of the scoring function for the short-circuit ratio. The weights are determined by the short-circuit ratio; the entropy weight method is used for weight allocation.

[0020] As a preferred embodiment of the droop control method for energy storage devices considering grid stability according to the present invention, wherein: the dynamic adjustment of the droop coefficient based on the grid stability assessment function through a mapping function includes, the droop coefficient being calculated based on the grid stability assessment function, and expressed as:

[0021]

[0022] in, The droop coefficient is adjusted. This is the initial droop coefficient. This is a mapping function from the stability function value to the adjustment coefficient.

[0023] This preferred scheme introduces a dynamic mapping function with the grid stability assessment function as the independent variable to achieve adaptive adjustment of the droop coefficient under different grid stability states. When the system stability is poor, the response intensity is automatically increased to improve the frequency regulation capability of the energy storage device; while when the grid state is stable, the original coefficient is maintained to avoid over-response, thereby achieving dynamic matching for different operating conditions and enhancing the overall system's regulation adaptability and frequency control accuracy.

[0024] As a preferred embodiment of the droop control method for energy storage devices considering grid stability according to the present invention, 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:

[0025]

[0026] The frequency-power response droop control is then expressed as:

[0027]

[0028] in, For adjustment coefficients, This refers to the change in active power that the energy storage device should output. This represents the frequency offset.

[0029] As a preferred embodiment of the droop control method for an energy storage device considering grid stability described in this invention, the output power of the energy storage device is expressed as:

[0030]

[0031] in, For energy storage output power, The initial power output of the energy storage device; perform output power judgment, if the output power... Exceeding the set maximum power limit Then the energy storage device needs to enter the power limiting protection state, limiting the power to [value missing]. and keep Output continues until the grid frequency stabilizes, avoiding over-regulation that could cause grid instability and overload the energy storage device; if the output power Less than the preset minimum power limit Then the power output should be increased, and the power output should be increased to... and keep Output power is used to ensure that the grid frequency no longer drops, thus preventing excessive degradation of frequency stability and avoiding system instability caused by further frequency decline; if the output power... If the power change rate is within the effective range, routine adjustments should continue, with appropriate responses made based on grid frequency changes; a power change rate assessment should be performed, and if the power change rate of the energy storage device exceeds the set maximum rate... If the rate of change is too fast, it indicates that the adjustment speed needs to be limited. The power change should be smoothed and the power adjustment rate should be limited to avoid grid oscillations. If the power change rate is within a reasonable range, normal adjustment can continue without additional restrictions.

[0032] This preferred solution effectively prevents system impact caused by power overshoot or excessive speed by constructing a dynamic limiting strategy; and sets power adjustment limiting and backoff strategies in conjunction with grid frequency recovery to ensure stable, continuous and controllable energy storage output, thereby enhancing the safety and engineering feasibility of the system in actual operation.

[0033] This invention provides a droop control method system for energy storage devices that takes into account grid stability.

[0034] To address the aforementioned technical problems, this invention provides the following technical solution: a droop control method system for energy storage devices considering grid stability, comprising: a data acquisition module, a grid stability assessment function construction module, a droop coefficient adjustment module, and a monitoring and feedback module; the data acquisition module is used to collect grid state information and obtain current grid operating state data; the grid stability assessment function construction module is used to construct a grid stability assessment function based on a scoring function of the grid operating state data; the droop coefficient adjustment module is used to dynamically adjust the droop coefficient based on the grid stability assessment function through a mapping 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.

[0035] The present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, characterized in that the processor executes the computer program to implement the steps of the described method for droop control of an energy storage device considering grid stability.

[0036] 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, it implements the steps of the above-described energy storage device droop control method considering grid stability.

[0037] The beneficial effects of this invention are as follows: By integrating multi-dimensional grid state parameters such as frequency offset, frequency change rate, voltage offset, and short-circuit ratio, this invention constructs a unified grid stability assessment function and dynamically adjusts the droop control coefficient of the energy storage device accordingly, achieving real-time identification and differentiated response to grid stability. This mechanism enhances power regulation capability when grid disturbances intensify and maintains flexible response when the grid is operating smoothly, thereby effectively improving the frequency regulation accuracy and stability of the energy storage system. Furthermore, this invention employs the entropy weight method to adaptively calculate the weights of each state indicator, avoiding errors caused by subjective weighting and enhancing the objectivity and identification capability of the assessment results. By setting upper and lower limits for power output and the maximum power change rate, dynamic constraints on the power regulation process are achieved, effectively suppressing power jumps, grid system over-adjustment, or energy storage overload problems, ensuring the stability of the control process and equipment safety. Overall, this invention improves the response flexibility and engineering feasibility of energy storage systems in complex grid operating environments, possessing strong practical value and promising prospects for widespread application. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a general flowchart of a droop control method for an energy storage device that takes into account grid stability, provided as an embodiment of the present invention. Detailed Implementation

[0040] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0041] Example 1, referring to Figure 1 This is one embodiment of the present invention, which provides a droop control method for an energy storage device that takes into account grid stability, including:

[0042] S1. Collect power grid status information and obtain current power grid operation status data.

[0043] S2. Construct a power grid stability assessment function based on the scoring function of power grid operation status data.

[0044] S3. Based on the power grid stability assessment function, the droop coefficient is dynamically adjusted through a mapping function.

[0045] S4. Calculate the power regulation of the energy storage device using the droop coefficient to obtain the output power of the energy storage device, thereby regulating the grid frequency and performing monitoring and feedback.

[0046] It should be noted that in the current power system, grid frequency is frequently affected by factors such as renewable energy fluctuations and weakened grid structure, resulting in frequent frequency drift. Traditional droop control methods, which use fixed coefficients, have insufficient regulation capacity under weak grid conditions and may cause over-response under strong grid conditions, affecting frequency stability. In addition, the response capability of energy storage devices is limited by the degree of matching between their power range and control strategy. Therefore, in order to solve the problems of insufficient grid state perception, strong response rigidity, and mismatched regulation capabilities, this embodiment constructs a complete grid state perception and response regulation mechanism through the above steps S1 to S5.

[0047] This mechanism can autonomously assess the stability of the power grid based on real-time grid status data and dynamically adjust the response coefficient of the energy storage system, thereby achieving precise and reasonable frequency regulation under different operating conditions. In particular, when the power grid experiences severe disturbances or insufficient stability, the system can proactively enhance its response; when the power grid is stable, it maintains flexible output to avoid over-adjustment, significantly improving the adaptability and control performance of the energy storage device in grid-connected operation.

[0048] Example 2, an embodiment of the present invention, provides a droop control method for an energy storage device considering grid stability, based on the previous embodiment, comprising:

[0049] In step S1, power grid status information is collected to obtain current power grid operating status data.

[0050] The power grid status information includes frequency offset, frequency change rate, voltage offset, and short-circuit ratio.

[0051] Frequency offset refers to the instantaneous deviation of the actual power grid operating frequency from 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 a DFT frequency tracker) configured at the grid connection point of the energy storage device.

[0052] The frequency offset is obtained by comparing it with the reference frequency of the power grid system (e.g., 50Hz), and is expressed as:

[0053]

[0054] in, The frequency value at time t. As the reference frequency, This represents the frequency offset at time t.

[0055] The frequency 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.

[0056] Define a fixed time interval as the calculation window for the Rate of Change of Frequency (ROCOF). The value of the rate of change of frequency at time t is calculated as follows:

[0057]

[0058] in, for Rate of change of frequency at time, for Frequency offset at time, For time intervals.

[0059] To avoid RoCoF anomalies caused by harmonic noise, communication jitter, or sampling transients, the original RoCoF sequence is processed by a three-point median filter, as shown below:

[0060]

[0061] in, for The rate of change of frequency after median filtering at three points at time t. for Rate of change of frequency at time, for Rate of change of frequency at time, To perform median filtering on the three input values, the middle value among the three is taken as the smoothed value of the current RoCoF, which is used to suppress outlier fluctuations.

[0062] Voltage offset: The energy storage device is also equipped with a voltage sampling device at the grid connection point, and uses a voltage transformer (VT) to transform the high voltage signal of the power grid into the measurable range of the control system.

[0063] The voltage signal is sampled through an analog-to-digital conversion (ADC) module, and the sampling frequency is recommended to be no less than 5kHz to ensure that voltage fluctuation details are captured.

[0064] The controller acquires instantaneous sampled values. , , This corresponds to the three-phase bus voltage.

[0065] Using the A-phase voltage as a representative, the root mean square (RMS) value of the phase voltage is calculated within a sliding window on the sampled signal to obtain the effective value of the phase voltage.

[0066]

[0067] in, This is the effective value of the phase voltage. This represents the number of sampling points within the sliding window. The first phase voltage The sampled values ​​of each sampling point For the first One sampling point.

[0068] The initial voltage offset is obtained by comparing the real-time effective voltage value with the preset rated voltage, and is expressed as:

[0069]

[0070] in, for The initial voltage offset at time t. for The effective value of the phase voltage at time t. This is the preset rated voltage.

[0071] To enhance anti-interference capabilities, it is possible to... Introducing a first-order low-pass filter, the filter function has the following form:

[0072]

[0073] in, for Voltage offset after filtering at any time. for Voltage offset after filtering at any time. These are the filter coefficients, which are automatically adjusted based on the disturbance intensity or signal noise. Value, low noise during normal operation, setting Small (mainly stable); when disturbances occur, the changes are drastic. Improve (fast tracking); settings The range is 0.1 to 0.3.

[0074] Noise levels can be estimated using the standard deviation σ. Adjustments are made to define the maximum and minimum standard deviation thresholds and the corresponding range of filter coefficients, expressed as follows:

[0075]

[0076] in, for Time-based filter coefficients The minimum filter coefficient, The maximum filter coefficient, For voltage standard deviation, The minimum standard deviation threshold, The maximum standard deviation threshold.

[0077] The short-circuit ratio (SCR) is an estimated ratio at the grid connection point of an energy storage device and serves as a primary structural indicator for assessing the strength of the power grid. The 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 SCR indicates a weaker power grid. The short-circuit ratio can be calculated as follows:

[0078]

[0079] in, for Short-circuit ratio at any time; for The short-circuit capacity of the grid connection point at any given time, which is the maximum apparent power that the system can provide when the point is short-circuited; The rated capacity of the connected energy storage device.

[0080] The short-circuit capacity of the grid connection point can be calculated in the following way:

[0081]

[0082] in, This is the equivalent positive-sequence impedance traced back from the grid connection point to the substation.

[0083] Furthermore, in step S2, a power grid stability assessment function is constructed based on the scoring function of the power grid operating status data.

[0084] This step aims to construct a unified power grid stability evaluation function based on the multi-dimensional power grid state parameters collected in step S1, which is used to quantify the stability of the current power grid operation and serve as the driving input for subsequent droop control parameter tuning.

[0085] First, the current power grid operating status data obtained by S1 is categorized into a vector form, as follows:

[0086]

[0087] in, This is a data vector representing the current power grid operating status.

[0088] The scoring interval of the scoring function consists of two thresholds. and Sure, This represents the allowable value for operating status data when the power grid is in a stable state. This indicates the threshold value at which instability or a strong response is required. The scoring function for each operating state data is within the interval... The score decreases linearly within the interval, and is 0 outside the interval, indicating that the system's operating state is unacceptable.

[0089] The piecewise scoring function for the state variables is represented as follows:

[0090]

[0091]

[0092] in, The first data vector representing the current power grid operating status One indicator, The first data vector representing the current power grid operating status The permissible values ​​of each indicator when the power grid is in a stable state. The first data vector representing the current power grid operating status The critical value at which an indicator reaches an unstable state. An indicator refers to operational status data.

[0093] The permissible and critical values ​​of the indicators are set according to relevant industry standards and the stability requirements of energy storage devices.

[0094] The power grid stability assessment function is constructed by weighted summation of the various score results, and is expressed as follows:

[0095]

[0096]

[0097] in, For power grid stability assessment function, The value of the scoring function for the frequency offset. As the weight of the frequency offset, The value of the scoring function for the rate of change of frequency. As the weight of the rate of change of frequency, The value of the scoring function for voltage offset. As the weight of voltage offset, The value of the scoring function for the short-circuit ratio. The weight of the short-circuit ratio.

[0098] , , and It is derived from the piecewise scoring function of the state variables.

[0099] 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 dispersion of different scoring indicators under multiple disturbance conditions, the contribution of each indicator to the system identification capability is quantified, thereby assigning it a corresponding weight value.

[0100] The entropy weight method is based on the theory of information entropy, which holds that the greater the variability of an index value in a sample, the more information it provides, and the greater its weight should be, and vice versa.

[0101] Set m typical disturbance conditions (such as different load changes, fault location, power supply access, etc.), and calculate the four scoring function values ​​defined in this invention for each condition. That is, the value of the scoring function for the frequency offset. That is, the value of the scoring function of the rate of change of frequency. That is, the value of the scoring function for voltage offset. The value of the scoring function for the short-circuit ratio.

[0102] The perturbation score matrix is ​​constructed as follows:

[0103]

[0104] in, , indicating the first In the first disturbance condition The value of the scoring function for each indicator;

[0105] The perturbation score matrix is ​​normalized column by column, and each column is normalized. (That is, the scoring function of each indicator) is normalized by weighting, and expressed as:

[0106]

[0107] in, For the normalized first In the first disturbance condition The value of the scoring function for each indicator.

[0108] The normalized weight matrix is ​​represented as follows:

[0109]

[0110] in, This is the normalized weight matrix.

[0111] And for each column satisfy .

[0112] The information entropy of the scoring function for each column is calculated as follows:

[0113]

[0114]

[0115] in, For the first Information entropy of the scoring function for each indicator is the entropy normalization constant.

[0116] like If it is 0, then define Set to 0 to avoid abnormal values.

[0117] Reflecting the first The scoring function of each indicator represents the information balance 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.

[0118] The information utility value is calculated based on information entropy and expressed as follows:

[0119]

[0120] in, For the first The information utility of the scoring function of each indicator, that is, its ability to identify in the overall evaluation.

[0121] The weights of each rating function are calculated based on the utility value and are expressed as follows:

[0122]

[0123] in, For the first The weight of each indicator.

[0124] And it satisfies the normalization condition:

[0125]

[0126] The calculated weights will be used to construct the comprehensive stability function, which serves as a key input to the droop parameter adjustment module in the energy storage control system. This function drives the dynamic updating of the droop coefficient, enabling the energy storage device to respond to and regulate changes in the grid state in real time.

[0127] In step S3, the droop coefficient is dynamically adjusted through a mapping function based on the power grid stability assessment function.

[0128] In existing technologies, 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 a synchronous generator, and output the corresponding active power adjustment value according to the grid frequency offset, expressed as:

[0129]

[0130] in, This refers to the change in active power that the energy storage device should output. This is the frequency offset. The droop factor represents the power regulation capability corresponding to a unit frequency offset.

[0131] In this application, to address the problems of rigid response, abrupt adjustment, and lack of grid stability awareness in existing droop control methods, a method based on a stability evaluation function is proposed. The droop coefficient self-tuning control mechanism.

[0132] The present invention uses the droop coefficient therein Change to a function based on power grid stability assessment dynamic quantity , is represented as:

[0133]

[0134] in, The droop coefficient is adjusted. The initial droop factor is set based on the rated capacity and frequency regulation margin of the energy storage device. This is the mapping function from the stability function value to the adjustment coefficient. When When it tends towards 1 (power grid stability), It also tends towards 1, that is, maintaining a normal response; when When it approaches 0 (power grid instability), If the value is greater than 0, the response strength will be automatically increased.

[0135] The design goal of the mapping function is to maintain the original droop coefficient when the power grid is stable, and to increase the droop coefficient when the power grid is unstable, so as to enhance the regulation capability and avoid over-response that leads to system instability.

[0136] This application uses a linear mapping function to adjust the droop coefficient. The mapping function takes the following form:

[0137]

[0138] in, This is the regulation coefficient, used to control the increase in the droop coefficient when the power grid is unstable. It is set based on the specific characteristics of the power grid, the response capability of the energy storage device, and engineering experience, and is usually selected as a small value. When the power grid is relatively stable, the impact of the regulation coefficient is small. Stay Nearby; when the power grid is relatively unstable, the impact of the regulation coefficient increases. This will significantly improve the frequency regulation response of energy storage devices.

[0139] Based on the power grid stability assessment results and regulation coefficients, the droop coefficient is dynamically adjusted using a mapping function as follows:

[0140]

[0141] The frequency-power response droop control is then expressed as:

[0142]

[0143] In step S4, the power regulation of the energy storage device is calculated using the droop coefficient to obtain the output power of the energy storage device, so as to regulate the grid frequency and perform monitoring and feedback.

[0144] The energy storage output power is then expressed as:

[0145]

[0146] in, For energy storage output power, This is the initial power output of the energy storage device, typically the normal operating power of the device without any adjustments.

[0147] To prevent over-regulation from causing overload of the energy storage device, maximum and minimum power limits are set as follows:

[0148]

[0149] in, This is 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, and it is usually set to a negative value). This is the maximum output power of the energy storage device (i.e., the energy storage device should output power when the frequency is too low to avoid over-response). The settings are based on the rated capacity and maximum discharge capability of the energy storage device, selecting the smaller of the two values ​​as the optimal value. ; The settings are based on the rated capacity and minimum discharge capability of the energy storage device, selecting the larger of the negative value of the rated capacity and the minimum discharge capability as the optimal value. .

[0150] The rate of change of the output power of energy storage devices also needs to be limited to prevent excessively rapid power changes from causing grid oscillations.

[0151]

[0152] in, For energy storage devices in The change in power at any given time. for Energy storage output power at any given time for Energy storage output power at all times The time interval for power changes. The rate of change of power. The maximum power response rate limit represents the maximum power change rate of the energy storage device per unit time. It prevents the energy storage device from generating an excessively fast response during frequency regulation and avoids impacting the power grid. It is determined based on the maximum charging and discharging power of the energy storage device and the time constant.

[0153] If output power Exceeded the set maximum power limit Then the energy storage device needs to enter the power limiting protection state, limiting the power to [value missing]. And maintain this output until the grid frequency changes return to stability, avoiding over-regulation that could cause grid instability or overload the energy storage device.

[0154] If output power Less than the preset minimum power limit Then the power output should be increased, and the power output should be increased to... And maintain this output to ensure that the grid frequency no longer drops, so as to ensure that the frequency stability is not excessively reduced and to avoid the system instability caused by the continued drop in frequency.

[0155] If output power If the situation is within the effective range, routine adjustments should continue, and appropriate responses should be made according to changes in grid frequency.

[0156] After the energy storage device determines the power level, if a deviation still exists between the current power and the target power, a gradual adjustment strategy is adopted based on the recovery of the grid frequency. During the recovery process, the adjustment amplitude is gradually reduced: if the grid frequency is already close to the target range, the power adjustment amplitude is gradually reduced to avoid frequent power fluctuations negatively impacting the grid. If the grid frequency fluctuation is large (e.g., a frequency deviation greater than ±0.2 Hz), the feedback gain is increased to provide a stronger power regulation response, helping the grid quickly return to stability.

[0157] The power change rate is judged, and if the power change rate of the energy storage device exceeds the set maximum rate... This indicates that the adjustment is too rapid, which may cause grid oscillations or overshoot. Therefore, the adjustment speed needs to be limited, power changes need to be smoothly controlled, the power adjustment rate needs to be limited, and grid oscillations should be avoided.

[0158] If the rate of power change is within a reasonable range, continue normal adjustment without additional restrictions.

[0159] Example 3, an embodiment of the present invention, provides a droop control method system for energy storage devices that considers grid stability, including a data acquisition module, a grid stability assessment function construction module, a droop coefficient adjustment module, and a monitoring feedback module.

[0160] The data acquisition module is used to collect power grid status information and obtain current power grid operating status data.

[0161] The power grid stability assessment function construction module is used to construct power grid stability assessment functions based on the scoring function of power grid operating status data.

[0162] The droop coefficient adjustment module is used to dynamically adjust the droop coefficient based on the power grid stability assessment function through a mapping function.

[0163] The monitoring and feedback module is used to calculate the power regulation 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.

[0164] This embodiment also provides an electronic device applicable to a droop control method for an energy storage device considering grid stability, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the droop control method for an energy storage device considering grid stability as proposed in the above embodiment.

[0165] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a droop control method for an energy storage device that considers grid stability, as proposed in the above embodiments.

[0166] The storage medium proposed in this embodiment belongs to the same inventive concept as the droop control method for an energy storage device that takes into account grid stability proposed in the above embodiments. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0167] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, 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, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0168] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A droop control method for an energy storage device considering grid stability, characterized in that: Comprising, Collecting power grid state information to obtain current power grid operating state data; Building a power grid stability evaluation function based on a scoring function of the power grid operating state data; Dynamically adjusting the droop coefficient based on the power grid stability evaluation function through a mapping function; Through the droop coefficient, calculating the power adjustment amount of the energy storage device to obtain the output power of the energy storage device to adjust the power grid frequency and perform monitoring and feedback; The current power grid operating state data includes frequency offset, frequency change rate, voltage offset, and short circuit ratio; According to the comparison between the current frequency value and the power grid system reference frequency, the frequency offset is obtained; The fixed time interval is defined as the frequency change rate calculation window, at time The frequency change rate value calculation is expressed as, wherein is a rate of change of the frequency at the time instant, is a frequency offset at the time instant, is a frequency offset at the time instant, is a time interval; And the original RoCoF sequence is processed by three-point median filtering; Obtaining three-phase bus voltage, obtaining phase voltage effective value, comparing real-time voltage effective value with preset rated voltage to obtain initial voltage offset, introducing 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.

2. The droop control method of energy storage device considering grid stability according to claim 1, characterized in that: The power grid stability evaluation function is built based on the scoring function of the power grid operating state data, comprising, The obtained current power grid operating state data is formed into a vector form and represented as, wherein, is the current grid operating state data vector, is is the frequency rate of change after three-point median filtering at the moment, is is the filtered voltage offset at the moment, is is the short circuit ratio at the moment; Building a state quantity segmented scoring function according to the current power grid operating state data; The scoring results of each item of the current power grid operating state data are constructed into a power grid stability evaluation function through weighted summation.

3. The droop control method of energy storage device considering grid stability according to claim 2, characterized in that: The state quantity segmented scoring function is represented as, wherein is the index of the current grid operating state data vector, is the index of the current grid operating state data vector, is the index of the current grid operating state data vector, is the index of the current grid operating state data vector, is the index of the current grid operating state data vector, is the index of the current grid operating state data vector, The power grid stability evaluation function is constructed through weighted summation, represented as, wherein, is a comprehensive stability evaluation function, is a value of a score function of the frequency deviation amount, is a weight of the frequency deviation amount, is a value of a score function of the frequency change rate, is a weight of the frequency change rate, is a value of a score function of the voltage deviation amount, is a weight of the voltage deviation amount, is a value of a score function of the short-circuit ratio, is a weight of the short-circuit ratio; The weight distribution is performed by using the entropy weight method.

4. The droop control method of energy storage device considering grid stability according to claim 3, characterized in that: The droop coefficient is dynamically adjusted based on the power grid stability evaluation function through a mapping function, comprising, The droop coefficient is calculated based on the power grid stability evaluation function and represented as, wherein is the adjusted droop coefficient, is the initial droop coefficient, is a mapping function from the stability function value to the adjusted coefficient.

5. The droop control method of energy storage device considering grid stability according to claim 4, characterized in that: The mapping function from the stability function value to the adjustment coefficient includes using a linear mapping function to adjust the droop coefficient, represented as, The frequency-power response relationship droop control is represented as, wherein, is a tuning coefficient, is a change in active power that the energy storage device should output, is a frequency offset.

6. The droop control method of energy storage device considering grid stability according to claim 5, characterized in that: The output power of the energy storage device is represented as, wherein, 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 set maximum power limit Then the energy storage device needs to enter the power limiting protection state, limiting the power to [value missing]. and keep The output continues until the grid frequency changes stabilize, avoiding over-regulation that could cause grid instability and overload the energy storage device. If the output power is less than the preset minimum power lower limit , the power output should be increased, the power output is increased to , and the output is maintained to ensure that the grid frequency does not continue to drop, so as to ensure that the frequency stability is not excessively reduced, and to avoid the system instability caused by the continuous drop of the frequency. If the output power is within the active range, then normal regulation should continue to be performed, with modest response to grid frequency changes; The power change rate is judged, and if the power change rate of the energy storage device exceeds a set maximum rate , it indicates that the adjustment is too fast, and the adjustment speed needs to be limited. The power change is controlled smoothly, the power adjustment rate is limited, and the power grid is prevented from appearing shock. If the power change rate is within a reasonable range, continue normal adjustment without additional restrictions.

7. A droop control method of energy storage device considering grid stability, applying the droop control method of energy storage device considering grid stability according to any one of claims 1-6, characterized in that, Comprising, Data acquisition module, power grid stability evaluation function construction module, droop coefficient adjustment module, and monitoring feedback module; The data acquisition module is used to collect power grid state information to obtain current power grid operating state data; The power grid stability evaluation function construction module is used to build a power grid stability evaluation function based on a scoring function of the power grid operating state data; The droop coefficient adjustment module is used to dynamically adjust the droop coefficient based on the power grid stability evaluation function through a mapping function; The monitoring feedback module is used to calculate the power adjustment amount of the energy storage device through the droop coefficient to obtain the output power of the energy storage device to adjust the power grid frequency and perform monitoring and feedback.

8. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that, The processor executes the computer program to realize the steps of the energy storage device droop control method considering power grid stability in any one of claims 1 to 6.

9. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the energy storage device droop control method considering power grid stability in any one of claims 1 to 6.

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