Power grid frequency modulation control method, device, equipment, system and medium

Abstract

This invention provides a control method, apparatus, device, system, and medium for power grid frequency regulation, relating to the field of power grid frequency regulation technology. The method includes: obtaining the State of Charge (SOC) value of flywheel energy storage; determining the frequency regulation range of flywheel energy storage based on the SOC value; controlling the flywheel energy storage to participate in power grid frequency regulation when the grid frequency is within the frequency regulation range; and controlling battery energy storage to participate in power grid frequency regulation when the grid frequency exceeds the frequency regulation range. This invention can improve frequency regulation efficiency and reduce energy storage device losses.

Description

Technical Field

[0001] This invention relates to the field of power grid frequency regulation technology, and in particular to a control method, device, equipment, system and medium for power grid frequency regulation. Background Technology

[0002] In the context of building a new power system, the stability of the power grid frequency is crucial. Energy storage devices, especially hybrid energy storage systems combining flywheel and battery energy storage, have become a key means to improve the power quality and operational reliability of the power grid due to their rapid and precise frequency regulation capabilities.

[0003] In related technologies, the frequency regulation tasks of flywheel energy storage and battery energy storage are typically allocated based on a fixed frequency fluctuation threshold. Specifically, when the grid frequency fluctuation is within a small range (e.g., within ±0.5Hz), flywheel energy storage, with its fast response speed and long cycle life, is preferentially used for regulation; if the frequency regulation capability of flywheel energy storage is insufficient to smooth the fluctuation, battery energy storage is used as a supplement. When the grid frequency fluctuation exceeds this fixed frequency fluctuation threshold (e.g., greater than ±0.5Hz), battery energy storage, with its high energy density and long endurance, is directly used for processing.

[0004] However, the frequency modulation control strategy based on the fixed frequency fluctuation threshold has the problems of low frequency modulation efficiency and easy equipment damage. Summary of the Invention

[0005] This invention provides a control method, device, equipment, system, and medium for power grid frequency regulation, in order to solve the problems of low frequency regulation efficiency and easy equipment loss in related technologies.

[0006] In a first aspect, embodiments of the present invention provide a control method for power grid frequency regulation, comprising:

[0007] Obtain the State of Charge (SOC) value of the flywheel energy storage;

[0008] Based on the SOC value, the frequency regulation range of the flywheel energy storage is determined;

[0009] When the grid frequency is within the frequency regulation range, the flywheel energy storage is controlled to participate in grid frequency regulation;

[0010] When the grid frequency exceeds the frequency regulation range, the battery energy storage is controlled to participate in grid frequency regulation.

[0011] In one possible implementation, determining the frequency regulation range of the flywheel energy storage based on the SOC value includes:

[0012] Obtain the mathematical mapping relationship between power grid frequency and frequency regulation power;

[0013] Based on the SOC value, the maximum charging and discharging power of the flywheel energy storage is determined;

[0014] Based on the maximum charging and discharging power and the mathematical mapping relationship, the upper and lower limits of the frequency modulation range are determined.

[0015] In one possible implementation, determining the upper and lower limits of the frequency modulation range based on the maximum charge / discharge power and the mathematical mapping relationship includes:

[0016] In the mathematical mapping relationship, the grid frequency corresponding to the maximum discharge power is determined as the lower limit of the frequency regulation range;

[0017] In the mathematical mapping relationship, the grid frequency corresponding to the maximum charging power is determined as the upper limit of the frequency regulation range.

[0018] In one possible implementation, determining the frequency regulation range of the flywheel energy storage based on the SOC value includes:

[0019] Obtain a preset lookup table; the lookup table contains different SOC ranges and the frequency modulation ranges corresponding to each SOC range;

[0020] The frequency regulation range of the flywheel energy storage is determined based on the SOC range in which the SOC value falls.

[0021] In one possible implementation, determining the frequency regulation range of the flywheel energy storage based on the SOC value includes:

[0022] Obtain a preset SOC key value, and based on the SOC key value, experimentally calibrate the frequency modulation range corresponding to the SOC key value;

[0023] The frequency regulation range of the flywheel energy storage is determined based on the first frequency regulation range corresponding to the minimum SOC key value greater than the SOC value, and the second frequency regulation range corresponding to the maximum SOC key value less than the SOC value.

[0024] In one possible implementation, determining the frequency regulation range of the flywheel energy storage based on a first frequency regulation range corresponding to a minimum SOC critical value greater than the SOC value and a second frequency regulation range corresponding to a maximum SOC critical value less than the SOC value includes:

[0025] Based on the lower limit of the first frequency modulation range and the lower limit of the second frequency modulation range, linear interpolation is performed to determine the lower limit of the frequency modulation range;

[0026] Based on the upper limit of the first frequency modulation range and the upper limit of the second frequency modulation range, linear interpolation is performed to determine the upper limit of the frequency modulation range.

[0027] Secondly, embodiments of the present invention provide a control device for power grid frequency regulation, comprising:

[0028] The acquisition module is used to acquire the SOC value of the flywheel energy storage;

[0029] The control module is used for:

[0030] Based on the SOC value, the frequency regulation range of the flywheel energy storage is determined;

[0031] When the grid frequency is within the frequency regulation range, the flywheel energy storage is controlled to participate in grid frequency regulation;

[0032] When the grid frequency exceeds the frequency regulation range, the battery energy storage is controlled to participate in grid frequency regulation.

[0033] Thirdly, embodiments of the present invention provide a control device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method described in the first aspect or any possible implementation thereof.

[0034] Fourthly, embodiments of the present invention provide a hybrid energy storage system, including flywheel energy storage, battery energy storage, and control equipment as described in the third aspect.

[0035] Fifthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method described in the first aspect or any possible implementation thereof.

[0036] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0037] To achieve precise matching between flywheel energy storage deployment and actual capacity, and improve flywheel energy storage utilization efficiency: By introducing the SOC value of flywheel energy storage to determine its frequency regulation range, flywheel energy storage can participate in grid frequency regulation based on its own capacity (determined by the SOC value). This avoids the problems in existing technologies where "flywheel energy storage is deployed within an incompatible range but cannot effectively regulate the frequency" or "flywheel energy storage capacity is not fully utilized" caused by using a fixed frequency fluctuation threshold. This ensures that the deployment of flywheel energy storage is adapted to its actual energy storage state, maximizing its frequency regulation role.

[0038] Reduce unnecessary charge-discharge cycles of battery energy storage and extend its service life: Battery energy storage is only controlled to participate in frequency regulation when the grid frequency exceeds the frequency regulation range corresponding to the flywheel energy storage's SOC. This avoids the situation in existing technologies where "frequency fluctuations that can be handled by flywheel energy storage are called up by battery energy storage" due to fixed frequency thresholds. This reduces unnecessary charge-discharge operations of battery energy storage, slows down the degradation rate of battery energy storage, helps extend its service life, and thus reduces the operation and maintenance costs of the energy storage system.

[0039] Improving the reliability and stability of power grid frequency regulation response: By controlling the flywheel energy storage to work effectively within the appropriate range and the battery energy storage to intervene in a timely manner when necessary, the power grid frequency fluctuations can be more accurately and timely smoothed out, thereby improving the reliability and stability of power grid frequency regulation. Attached Figure Description

[0040] Figure 1 This is an application scenario diagram of the power grid frequency regulation control method provided in the embodiments of the present invention;

[0041] Figure 2 This is a flowchart illustrating the implementation of the power grid frequency regulation control method provided in this embodiment of the invention.

[0042] Figure 3 This is a schematic diagram of the structure of the power grid frequency regulation control device provided in an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the control device provided in an embodiment of the present invention. Detailed Implementation

[0044] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0045] In related technologies, when using hybrid energy storage systems composed of flywheel energy storage and battery energy storage to participate in grid frequency regulation, the frequency regulation tasks of flywheel energy storage and battery energy storage are mostly allocated based on a fixed frequency fluctuation threshold. When the grid frequency fluctuation is less than the frequency fluctuation threshold (e.g., the grid frequency fluctuation is within ±0.5Hz), flywheel energy storage, which has a fast response speed and long cycle life, is preferentially used for regulation; if the frequency regulation capability of flywheel energy storage is insufficient to smooth the fluctuation, battery energy storage is then used as a supplement. When the grid frequency fluctuation exceeds the fixed frequency fluctuation threshold (e.g., the grid frequency fluctuation is greater than ±0.5Hz), battery energy storage, which has high energy density and long endurance, is directly used for processing.

[0046] The applicant's research has revealed that the aforementioned frequency regulation method, which uses a fixed frequency fluctuation threshold to call upon flywheel energy storage and battery energy storage, is prone to mismatches between the frequency regulation command and the actual frequency regulation capability of the flywheel energy storage. For example, when the grid frequency fluctuation is below the frequency fluctuation threshold, but the flywheel energy storage's frequency regulation capability is insufficient, it is still called upon, resulting in ineffective frequency regulation. Alternatively, when the grid frequency is above the frequency fluctuation threshold and the flywheel energy storage's frequency regulation capability is sufficient, battery energy storage is directly called upon, causing the flywheel energy storage to be underutilized and unnecessary calls to battery energy storage. Furthermore, due to the characteristics of battery energy storage, frequent calls to battery energy storage can also cause losses to the battery energy storage. In other words, the related technologies, when using flywheel energy storage and battery energy storage for grid frequency regulation, suffer from low frequency regulation efficiency and are prone to equipment damage.

[0047] To improve frequency regulation efficiency and reduce equipment losses, this invention pre-obtains the State of Charge (SOC) value of flywheel energy storage before performing grid frequency regulation. Based on this SOC value, the frequency regulation range of flywheel energy storage is determined. When the grid frequency is within this range, flywheel energy storage is directly invoked for grid frequency regulation. When the grid frequency exceeds this range, battery energy storage is directly invoked for grid frequency regulation. This ensures that the use of flywheel energy storage is adapted to its actual energy storage state, maximizing its frequency regulation function and improving frequency regulation efficiency. Furthermore, it reduces unnecessary charging and discharging operations of battery energy storage, slowing down its degradation rate. Simultaneously, the effective operation of flywheel energy storage within its suitable range and the timely intervention of battery energy storage when necessary enable more precise and timely suppression of grid frequency fluctuations, improving the reliability and stability of grid frequency regulation.

[0048] First refer to Figure 1 , Figure 1 The schematic diagram illustrates an application scenario provided by an embodiment of the present invention. The device involved in the application scenario includes a hybrid energy storage system, wherein the hybrid energy storage system includes a control device 101, a flywheel energy storage 102, and a battery energy storage 103.

[0049] When the application scenario is power grid frequency regulation control: the control device 101 obtains the SOC value of the flywheel energy storage 102 and determines the frequency regulation range of the flywheel energy storage 102 based on the SOC value; when the power grid frequency is within the frequency regulation range, the flywheel energy storage 102 is controlled to participate in power grid frequency regulation; when the power grid frequency exceeds the frequency regulation range, the battery energy storage 103 is controlled to participate in power grid frequency regulation.

[0050] The following is combined Figure 1 Application scenarios, refer to Figure 2 This invention describes a power grid frequency regulation control method provided by an embodiment of the present invention. It should be noted that the embodiments of the present invention can be applied to control equipment, meaning the power grid frequency regulation control method provided by the embodiments of the present invention can be executed on a control device.

[0051] See Figure 2 The document illustrates a flowchart of the power grid frequency regulation control method provided in an embodiment of the present invention, which is described in detail below:

[0052] Step 201: Obtain the SOC value of the flywheel energy storage.

[0053] This invention can acquire the grid frequency in real time. When the grid frequency fluctuation exceeds the frequency regulation dead zone, it determines to execute a grid frequency regulation strategy. Here, when executing the grid frequency regulation strategy, the SOC value of the flywheel energy storage is first acquired to determine the actual frequency regulation capability of the flywheel energy storage.

[0054] Here, the range of the frequency modulation dead zone can be determined according to the actual situation. For example, it can be 50±0.03Hz to avoid unnecessary frequent responses.

[0055] Step 202: Determine the frequency regulation range of flywheel energy storage based on the SOC value.

[0056] It is understandable that flywheel energy storage can increase the grid frequency when performing a discharge operation and decrease the grid frequency when performing a charging operation.

[0057] The charging and discharging capabilities of flywheel energy storage are affected by its State of Charge (SOC) value. A lower SOC value results in stronger charging capabilities but weaker discharging capabilities. Correspondingly, the upper limit of its adjustable frequency is higher. Conversely, a higher SOC value results in weaker charging capabilities but stronger discharging capabilities, and a lower lower limit of its adjustable frequency. Therefore, embodiments of the present invention can determine the frequency regulation range based on the SOC value of the flywheel energy storage.

[0058] Step 203: When the grid frequency is within the frequency regulation range, control the flywheel energy storage to participate in grid frequency regulation.

[0059] When the grid frequency is within the frequency regulation range of the flywheel energy storage, meaning that the flywheel energy storage's own frequency regulation capability can meet the current grid frequency regulation requirements, then directly controlling the flywheel energy storage to participate in grid frequency regulation can effectively solve the grid frequency fluctuation problem. At the same time, it can also reduce unnecessary intervention of battery energy storage and avoid additional losses of battery energy storage.

[0060] Step 204: When the grid frequency exceeds the frequency regulation range, control the battery energy storage to participate in grid frequency regulation.

[0061] When the grid frequency exceeds the frequency regulation range of the flywheel energy storage, meaning that the flywheel energy storage's own frequency regulation capability cannot meet the current grid frequency regulation requirements, the battery energy storage is directly controlled to participate in grid frequency regulation to avoid the problem of ineffective frequency regulation due to insufficient flywheel frequency regulation capability.

[0062] It should be clarified here that the frequency regulation range in the embodiments of the present invention refers to the frequency regulation range of flywheel energy storage determined based on the SOC value of flywheel energy storage.

[0063] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0064] To achieve precise matching between flywheel energy storage deployment and actual capacity, and improve flywheel energy storage utilization efficiency: By introducing the SOC value of flywheel energy storage to determine its frequency regulation range, flywheel energy storage can participate in grid frequency regulation based on its own capacity (determined by the SOC value). This avoids the problems in existing technologies where "flywheel energy storage is deployed within an incompatible range but cannot effectively regulate the frequency" or "flywheel energy storage capacity is not fully utilized" caused by using a fixed frequency fluctuation threshold. This ensures that the deployment of flywheel energy storage is adapted to its actual energy storage state, maximizing its frequency regulation role.

[0065] Reduce unnecessary charge-discharge cycles of battery energy storage and extend its service life: Battery energy storage is only controlled to participate in frequency regulation when the grid frequency exceeds the frequency regulation range corresponding to the flywheel energy storage's SOC. This avoids the situation in existing technologies where "frequency fluctuations that can be handled by flywheel energy storage are called up by battery energy storage" due to fixed frequency thresholds. This reduces unnecessary charge-discharge operations of battery energy storage, slows down the degradation rate of battery energy storage, helps extend its service life, and thus reduces the operation and maintenance costs of the energy storage system.

[0066] Improving the reliability and stability of power grid frequency regulation response: In this embodiment of the invention, the flywheel energy storage is controlled to work effectively within the appropriate range, and the battery energy storage is intervened in a timely manner when necessary, so that power grid frequency fluctuations can be smoothed more accurately and in a timely manner, thereby improving the reliability and stability of power grid frequency regulation.

[0067] The following section details the specific implementation methods for determining the frequency regulation range of flywheel energy storage. Here, the embodiments of the present invention provide three implementation methods for determining the frequency regulation range of flywheel energy storage based on its State of Charge (SOC) value.

[0068] In the first implementation, the embodiments of the present invention can first obtain the mathematical mapping relationship between the grid frequency and the frequency regulation power; then, based on the SOC value, determine the maximum charging and discharging power of the flywheel energy storage; finally, based on the maximum charging and discharging power and the mathematical mapping relationship, determine the upper and lower limits of the frequency regulation range.

[0069] Here, the mathematical mapping relationship between grid frequency and frequency regulation power is used to reflect the power value that the energy storage system needs to generate or absorb at any given grid frequency. This mathematical mapping relationship can be reflected by the frequency-power characteristic (FPC) curve.

[0070] The method for determining the mathematical mapping relationship (i.e., the FPC curve) between the above-mentioned power grid frequency and frequency regulation power is as follows:

[0071] First, the frequency reference deviation can be obtained from the relevant technical specifications, and the ratio of the rated power of the hybrid energy storage system to the frequency reference deviation can be calculated. This ratio can then be determined as the frequency modulation slope.

[0072] Here, for a hybrid energy storage system consisting of flywheel energy storage and battery energy storage, the rated power of the hybrid energy storage system can be the sum of the rated power of the flywheel energy storage and the rated power of the battery energy storage.

[0073] Frequency reference deviation refers to the frequency deviation that produces 100% of the rated power of the energy storage system. For example, the frequency reference deviation can be 0.2Hz, meaning that the hybrid energy storage system can only produce 100% power output when the grid frequency fluctuates by 0.2Hz above or below the rated frequency (e.g., 50Hz).

[0074] The frequency regulation slope refers to the frequency regulation power that the hybrid energy storage system needs to provide for every 1 Hz change in the grid frequency. For example, if the rated power of the hybrid energy storage system is 5 MW and the frequency reference deviation is 0.2 Hz, then the frequency regulation slope can be 5 MW / 0.2 Hz = 25 MW / Hz. That is, for every 0.1 Hz change in the grid frequency, the hybrid energy storage system needs to provide 2.5 MW of power output.

[0075] Next, the frequency modulation dead zone can be obtained from the relevant technical specifications, for example, 50±0.03Hz, which means that when the grid frequency is in the range of 50±0.03Hz, the required frequency modulation power is 0.

[0076] Finally, when the grid frequency exceeds the frequency regulation dead zone, the product of the change in grid frequency (i.e., the difference between the rated frequency of 50Hz and the grid frequency) and the above-mentioned frequency regulation slope can be calculated, and this product can be determined as the frequency regulation power required by the grid, thereby obtaining the mathematical mapping relationship between grid frequency and frequency regulation power.

[0077] Using the grid's rated frequency of 50Hz as a reference, when the grid frequency is within the frequency regulation dead zone (e.g., 50 ± 0.03Hz), the required frequency regulation power is 0 to avoid unnecessary frequent responses. When the grid frequency is higher than the upper limit of the frequency regulation dead zone (e.g., 50.03Hz), the energy storage system needs to perform charging operations to reduce the grid frequency, and the higher the grid frequency, the higher the required charging power. When the grid frequency is lower than the lower limit of the frequency regulation dead zone (e.g., 49.97Hz), the energy storage system needs to perform discharging operations to increase the grid frequency, and the lower the grid frequency, the higher the required discharging power.

[0078] In this embodiment of the invention, when the frequency modulation power is positive, it is used to characterize the discharge power; the larger the absolute value of the frequency modulation power, the greater the discharge power. When the frequency modulation power is negative, it is used to characterize the charging power; the larger the absolute value of the frequency modulation power, the greater the charging power.

[0079] The State of Charge (SOC) value of flywheel energy storage directly affects its charging and discharging capabilities. This invention allows for the determination of the charging and discharging capabilities based on the flywheel's SOC value. Here, its maximum charging and discharging power is used to characterize its charging and discharging capabilities.

[0080] The embodiments of the present invention can use experimental calibration to determine the maximum charge and discharge power corresponding to different SOC values ​​of flywheel energy storage.

[0081] Specifically, when the flywheel energy storage is at any SOC value, a discharge capability test is performed on the flywheel energy storage to determine the maximum discharge power of the flywheel energy storage at that SOC value:

[0082] When the flywheel energy storage is at any SOC value, its discharge power is gradually increased. After each increase in discharge power, it is stabilized for a set time (e.g., 30 seconds) until the flywheel energy storage reaches the discharge critical state. The discharge power that the flywheel energy storage can stably maintain at the discharge critical state is taken as the maximum discharge power of the flywheel energy storage at that SOC value.

[0083] Here, the flywheel energy storage is determined to have reached the critical discharge state when any of the following conditions are met:

[0084] 1. The rotational speed of the flywheel energy storage is reduced to the minimum limit; 2. The DC bus voltage inside the flywheel energy storage is reduced to the minimum allowable value.

[0085] When the flywheel energy storage is at any SOC value, a charging capacity test is performed on the flywheel energy storage to determine the maximum charging power of the flywheel energy storage at that SOC value:

[0086] When the flywheel energy storage is at any SOC value, its charging power is gradually increased. After each increase in charging power, it is stabilized for a set time (e.g., 30 seconds) until the flywheel energy storage reaches the charging critical state. The charging power that the flywheel energy storage can stably maintain at the charging critical state is taken as the maximum charging power of the flywheel energy storage at that SOC value.

[0087] Here, the flywheel energy storage is determined to have reached the charging critical state when any of the following conditions are met:

[0088] 1. The speed of the flywheel energy storage increases to the maximum limit; 2. The DC bus voltage inside the flywheel energy storage exceeds the maximum allowable value.

[0089] In some embodiments, the grid frequency corresponding to the maximum discharge power can be determined as the lower limit of the frequency regulation range in the mathematical mapping relationship; and the grid frequency corresponding to the maximum charging power can be determined as the upper limit of the frequency regulation range.

[0090] Here, in the mathematical mapping relationship between grid frequency and frequency regulation power, the grid frequency value corresponding to the maximum discharge power of flywheel energy storage can be determined. This grid frequency value is the lowest frequency at which flywheel energy storage can support the grid through discharge, which is the lower limit of the frequency regulation range.

[0091] In the mathematical mapping relationship between grid frequency and frequency regulation power, the grid frequency value corresponding to the maximum charging power of flywheel energy storage can be determined. This grid frequency value is the highest frequency that flywheel energy storage can support the grid through charging, which is the upper limit of the frequency regulation range.

[0092] The embodiments of the present invention determine the maximum charging and discharging power of the flywheel energy storage by the SOC value, and then determine its frequency regulation range. This can ensure that the frequency regulation range of the flywheel always closely follows its real-time capability boundary, and maximize its instantaneous frequency regulation potential while avoiding flywheel energy storage overload, thereby improving frequency regulation efficiency.

[0093] In the second implementation, the embodiments of the present invention can pre-establish a lookup table, which includes different SOC ranges and the corresponding frequency modulation ranges for each SOC range. When determining the frequency modulation range of flywheel energy storage, the pre-set lookup table can be obtained first; then, based on the SOC range in which the SOC value is located, the frequency modulation range of flywheel energy storage can be determined.

[0094] Here, the experimental calibration method can be adopted, taking the rated grid frequency of 50Hz as the benchmark, and testing the grid frequency boundary that the flywheel energy storage can stably smooth under different SOC ranges (e.g., 20~40%, 40~60%, 60~80%, 80%~100%), that is, the frequency regulation range corresponding to different SOC ranges.

[0095] Specifically, taking the SOC range of 20-40% as an example, the frequency modulation range corresponding to a calibrated SOC value of 20% and the frequency modulation range corresponding to a SOC value of 40% can be tested separately, and the intersection of the two frequency modulation ranges can be determined as the frequency modulation range corresponding to the SOC range of 20-40%.

[0096] The frequency modulation range corresponding to a SOC value of 20% and the frequency modulation range corresponding to a SOC value of 40% can be determined through experimental calibration.

[0097] First, select a period when the grid load fluctuation is less than ±2% and the output of new energy sources is stable, or construct a standard test scenario by simulating the grid load device and fixing the grid rated frequency at 50Hz.

[0098] A power analyzer and a frequency monitoring device are installed at the output end of the flywheel energy storage and the connection point with the power grid to collect power and frequency data.

[0099] When the SOC value of the flywheel energy storage is 20%, the grid disturbance device is used to lower the grid frequency to a first set frequency value, and the flywheel energy storage is activated to discharge and suppress frequency fluctuations, checking whether the grid frequency can recover to 50Hz. If the grid frequency fails to recover to 50Hz, the first set frequency value is increased to restore the SOC value of the flywheel energy storage to 20%, and the flywheel energy storage is reused for discharge until the grid frequency can recover to 50Hz. The first set frequency value at this point is then determined as the lower limit of the frequency regulation range.

[0100] It should be noted that the initial set frequency value should be a relatively low value so that the flywheel energy storage cannot restore the grid frequency to 50Hz, for example, 48Hz. This embodiment of the invention determines the lowest frequency that can be regulated when the flywheel energy storage's SOC value is 20%, i.e., the lower limit of the frequency regulation range, by continuously increasing the first set frequency value.

[0101] To improve the accuracy of the frequency modulation range, embodiments of the present invention can repeat the test calibration multiple times, calculate the average value of the lower limit of the frequency modulation range of each test calibration, and determine the average value as the final lower limit of the frequency modulation range.

[0102] When the flywheel energy storage's State of Charge (SOC) is 20%, the grid frequency is raised to a second set frequency value using a grid disturbance device. The flywheel energy storage is then activated to charge and smooth frequency fluctuations, and the grid frequency is checked to see if it can recover to 50Hz. If the grid frequency fails to recover to 50Hz, the second set frequency value is lowered to restore the flywheel energy storage's SOC to 20%, and the flywheel energy storage is used again for charging and smoothing until the grid frequency is confirmed to recover to 50Hz. This set frequency value is then determined as the upper limit of the frequency regulation power.

[0103] It should be noted that the initial second set frequency value should be a relatively high value so that the flywheel energy storage cannot restore the grid frequency to 50Hz, for example, 52Hz. This embodiment of the invention determines the highest frequency that can be regulated when the flywheel energy storage's SOC value is 20%, i.e., the upper limit of the frequency regulation range, by continuously decreasing the second set frequency value.

[0104] Similarly, to improve the accuracy of the frequency modulation range, multiple calibration tests can be performed, and the average value of the upper limit of the frequency modulation range from each calibration test can be calculated. This average value can then be used as the final upper limit of the frequency modulation range.

[0105] The test calibration method for the frequency modulation range corresponding to a SOC value of 40% is the same as the test calibration method described above, and will not be repeated here.

[0106] Alternatively, the first implementation method described above can be used to determine the frequency modulation range corresponding to a SOC value of 20%, and the method for determining the frequency modulation range corresponding to a SOC value of 40%. This will not be elaborated further here.

[0107] According to the above method, the embodiments of the present invention can determine the frequency modulation range corresponding to the upper and lower limits of different SOC ranges, and determine the frequency modulation range corresponding to different SOC ranges by taking the intersection, thereby establishing a lookup table so that the frequency modulation range corresponding to flywheel energy storage when it is at different SOC values ​​can be determined according to the lookup table.

[0108] Here, a basic lookup table method is used to quickly determine the frequency modulation range corresponding to different SOC values. It is simple, easy to implement, and has a fast response.

[0109] In the second implementation, if the SOC value of the flywheel energy storage changes slightly at a critical point (e.g., from 40.1% to 39.9%), the frequency regulation range will change significantly, potentially causing a hard switch between the flywheel and the battery, thus affecting frequency regulation stability. Furthermore, the significant change in the frequency regulation range can also impact the flywheel energy storage device itself. To avoid these problems, this embodiment of the invention provides a third implementation for determining the frequency regulation range of the flywheel energy storage.

[0110] In the third implementation, the embodiments of the present invention can obtain a preset SOC key value, and test-calibrate the frequency modulation range corresponding to the SOC key value based on the SOC key value; then, based on the first frequency modulation range corresponding to the smallest SOC key value greater than the SOC value, and the second frequency modulation range corresponding to the largest SOC key value less than the SOC value, the frequency modulation range of flywheel energy storage is determined.

[0111] Here, the SOC key value can be determined according to the actual situation. For example, it can be 20%, 40%, 60%, 80%, and 100%. The frequency modulation range corresponding to each SOC key value can be determined by experimental calibration.

[0112] The method for determining the frequency modulation range corresponding to each SOC key value can be found in the above-mentioned experimental calibration method or the first implementation method. It will not be elaborated further here.

[0113] When determining the frequency regulation range based on the State of Charge (SOC) value of flywheel energy storage, the two nearest critical SOC values ​​can be identified. Specifically, the smallest critical SOC value greater than the current SOC value and the largest critical SOC value less than the current SOC value. By performing linear interpolation on the frequency regulation ranges corresponding to these two critical SOC values, the frequency regulation range of the flywheel energy storage can be determined accordingly.

[0114] For example, when the SOC value of flywheel energy storage is 30%, the first frequency regulation range corresponding to the critical SOC value of 40% and the second frequency regulation range corresponding to the critical SOC value of 20% can be determined respectively, and the first frequency regulation range and the second frequency regulation range can be linearly interpolated to determine the frequency regulation range of flywheel energy storage.

[0115] In some embodiments, the lower limit of the frequency modulation range can be determined by linear interpolation based on the lower limit of the first frequency modulation range and the lower limit of the second frequency modulation range; and the upper limit of the frequency modulation range can be determined by linear interpolation based on the upper limit of the first frequency modulation range and the upper limit of the second frequency modulation range.

[0116] Taking a flywheel energy storage SOC of 30% as an example, the first frequency regulation range is: The second frequency modulation range is Then according to Determine the lower limit of the frequency modulation range, and based on... Determine the upper limit of the frequency regulation range of flywheel energy storage.

[0117] The embodiments of the present invention use piecewise linear interpolation to determine the frequency regulation range of flywheel energy storage, which can effectively avoid the problem of range jumps at interval switching points, realize a smooth transition between flywheel energy storage and battery energy storage, and improve the frequency regulation stability of the power grid.

[0118] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0119] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0120] Figure 3 A schematic diagram of the control device for power grid frequency regulation provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below:

[0121] like Figure 3 As shown, the control device 3 for power grid frequency regulation includes: an acquisition module 31 and a control module 32.

[0122] The acquisition module 31 is used to acquire the SOC value of the flywheel energy storage;

[0123] Control module 32 is used for:

[0124] Based on the SOC value, determine the frequency regulation range of flywheel energy storage;

[0125] When the grid frequency is within the frequency regulation range, the flywheel energy storage is controlled to participate in grid frequency regulation;

[0126] When the grid frequency exceeds the frequency regulation range, control the battery energy storage to participate in grid frequency regulation.

[0127] In one possible implementation, the control module 32 is specifically used for:

[0128] Obtain the mathematical mapping relationship between power grid frequency and frequency regulation power;

[0129] Based on the SOC value, determine the maximum charging and discharging power of flywheel energy storage;

[0130] Based on the maximum charging and discharging power and the mathematical mapping relationship, the upper and lower limits of the frequency modulation range are determined.

[0131] In one possible implementation, the control module 32 is specifically used for:

[0132] In the mathematical mapping relationship, the grid frequency corresponding to the maximum discharge power is determined as the lower limit of the frequency regulation range;

[0133] In the mathematical mapping relationship, the grid frequency corresponding to the maximum charging power is determined as the upper limit of the frequency regulation range.

[0134] In one possible implementation, the control module 32 is specifically used for:

[0135] Obtain the preset lookup table; the lookup table contains different SOC ranges and the corresponding frequency modulation ranges for each SOC range;

[0136] The frequency regulation range of flywheel energy storage is determined based on the SOC range in which the SOC value falls.

[0137] In one possible implementation, the control module 32 is specifically used for:

[0138] Obtain the preset SOC key value, and based on the SOC key value, experimentally calibrate the frequency modulation range corresponding to the SOC key value;

[0139] The frequency regulation range of flywheel energy storage is determined based on the first frequency regulation range corresponding to the minimum critical SOC value greater than the SOC value, and the second frequency regulation range corresponding to the maximum critical SOC value less than the SOC value.

[0140] In one possible implementation, the control module 32 is specifically used for:

[0141] Based on the lower limit of the first frequency modulation range and the lower limit of the second frequency modulation range, linear interpolation is performed to determine the lower limit of the frequency modulation range.

[0142] Based on the upper limit of the first frequency modulation range and the upper limit of the second frequency modulation range, linear interpolation is performed to determine the upper limit of the frequency modulation range.

[0143] This device embodiment can be used to implement the above method embodiment, and its technical principle and implementation effect are the same as those of the above method embodiment, so they will not be repeated here.

[0144] Figure 4 This is a schematic diagram of the control device provided in an embodiment of the present invention. Figure 4 As shown, the control device in this embodiment includes a processor 40 and a memory 41. The memory 41 stores a computer program 42. When the processor 40 executes the computer program 42, it implements the steps in the various method embodiments described above. Alternatively, when the processor 40 executes the computer program 42, it implements the functions of each module / unit in the various device embodiments described above.

[0145] For example, computer program 42 may be divided into one or more modules / units, which are stored in memory 41 and executed by processor 40 to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 42 in a control device.

[0146] The control device may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will understand that... Figure 4 This is merely an example of control device 4 and does not constitute a limitation on the control device. It may include more or fewer components than shown, or combine certain components, or different components. For example, the control device may also include input / output devices, network access devices, buses, etc.

[0147] The processor 40 can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0148] The memory 41 can be an internal storage unit of the control device, such as the hard drive or RAM of the control device. The memory 41 can also be an external storage device of the control device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the control device. Furthermore, the memory 41 can include both internal and external storage units of the control device. The memory 41 is used to store the computer program 42 and other programs and data required by the control device. The memory 41 can also be used to temporarily store data that has been output or will be output.

[0149] For the sake of simplicity and clarity, only the above-described functional modules / units are used as examples. In practical applications, the functions described above can be assigned to different functional modules / units as needed. These modules / units can be implemented in hardware, software, or a combination of both.

[0150] This invention also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the methods described in the above-described method embodiments.

[0151] This invention also provides a computer program product, including a computer program. When the computer program is executed by a processor, it implements the methods described in the above-described method embodiments.

[0152] Computer programs include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. Computer-readable media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0153] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not detailed or described in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Unless otherwise specified or in conflict with logic, the terminology and / or descriptions between different embodiments are consistent and can be referenced interchangeably. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0154] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A control method for power grid frequency regulation, characterized in that, include: Obtain the SOC value of flywheel energy storage; Based on the SOC value, the frequency regulation range of the flywheel energy storage is determined; The lower the SOC value, the higher the upper limit of the frequency modulation range; The higher the SOC value, the smaller the lower limit of the frequency modulation range; When the grid frequency is within the frequency regulation range, the flywheel energy storage is controlled to participate in grid frequency regulation; When the grid frequency exceeds the frequency regulation range, control the battery energy storage to participate in grid frequency regulation; Determining the frequency regulation range of the flywheel energy storage based on the SOC value includes: Obtain a preset SOC key value, and based on the SOC key value, experimentally calibrate the frequency modulation range corresponding to the SOC key value; The frequency regulation range of the flywheel energy storage is determined based on the first frequency regulation range corresponding to the minimum SOC key value that is greater than the SOC value, and the second frequency regulation range corresponding to the maximum SOC key value that is less than the SOC value. The determination of the frequency regulation range of the flywheel energy storage based on the first frequency regulation range corresponding to the minimum SOC critical value greater than the SOC value and the second frequency regulation range corresponding to the maximum SOC critical value less than the SOC value includes: Based on the lower limit of the first frequency modulation range and the lower limit of the second frequency modulation range, linear interpolation is performed to determine the lower limit of the frequency modulation range; Based on the upper limit of the first frequency modulation range and the upper limit of the second frequency modulation range, linear interpolation is performed to determine the upper limit of the frequency modulation range.

2. A control device for power grid frequency regulation, characterized in that, include: The acquisition module is used to acquire the SOC value of the flywheel energy storage; The control module is used for: Based on the SOC value, the frequency regulation range of the flywheel energy storage is determined; The lower the SOC value, the larger the upper limit of the frequency modulation range; the higher the SOC value, the smaller the lower limit of the frequency modulation range. When the grid frequency is within the frequency regulation range, the flywheel energy storage is controlled to participate in grid frequency regulation; When the grid frequency exceeds the frequency regulation range, control the battery energy storage to participate in grid frequency regulation; Determining the frequency regulation range of the flywheel energy storage based on the SOC value includes: Obtain a preset SOC key value, and based on the SOC key value, experimentally calibrate the frequency modulation range corresponding to the SOC key value; The frequency regulation range of the flywheel energy storage is determined based on the first frequency regulation range corresponding to the minimum SOC key value that is greater than the SOC value, and the second frequency regulation range corresponding to the maximum SOC key value that is less than the SOC value. The determination of the frequency regulation range of the flywheel energy storage based on the first frequency regulation range corresponding to the minimum SOC critical value greater than the SOC value and the second frequency regulation range corresponding to the maximum SOC critical value less than the SOC value includes: Based on the lower limit of the first frequency modulation range and the lower limit of the second frequency modulation range, linear interpolation is performed to determine the lower limit of the frequency modulation range; Based on the upper limit of the first frequency modulation range and the upper limit of the second frequency modulation range, linear interpolation is performed to determine the upper limit of the frequency modulation range.

3. A control device, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the method as described in claim 1.

4. A hybrid energy storage system, characterized in that, It includes flywheel energy storage, battery energy storage, and the control device as described in claim 3.

5. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method as described in claim 1.

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