Method and device for determining discharge time of power grid energy storage system, equipment and medium

Abstract

The embodiment of the invention discloses a method and device for determining the discharge time of a power grid energy storage system, equipment and a medium. The method comprises the steps that if it is determined that the frequency change of a power grid system meets a preset frequency reduction condition, the predicted power grid frequency of the power grid system at candidate discharge time is determined based on a power grid system frequency response time domain analytic expression; determining the lowest frequency of the power grid system after the discharge of the energy storage system is finished according to the candidate discharge time and the power grid system frequency response time domain analytic expression; and determining the candidate discharge time when the predicted power grid frequency and the lowest frequency meet the preset frequency requirement as the final discharge time of the energy storage system. According to the technical scheme, the predicted power grid frequency and the candidate discharge time when the lowest frequency meets the preset frequency requirement are determined as the final discharge time of the energy storage system, the energy storage system injects power into the power grid system at the final discharge time when the frequency of the power grid system is reduced, and the influence of frequency fluctuation on the power grid system is reduced.

Description

Technical Field

[0001] The present invention relates to the field of power grid technology, and in particular to a method, device, equipment and medium for determining the discharge time of a power grid energy storage system. Background Art

[0002] In the power grid system, new energy systems (such as wind power and photovoltaic systems) generally have constant power output under conventional control methods and provide almost no frequency support for the grid. Energy storage systems (ESSs) have become a key element in modern power grid systems and play an important role in the frequency adjustment of the grid.

[0003] At present, the strategies for frequency control through ESSs mainly include proportional control, droop control, virtual inertia control and other strategies. The above control strategies are not conducive to the poor regulation ability of system frequency. For example, virtual inertia control plays a role in suppressing the frequency change rate in the early stage of system disturbance, but the system frequency recovery speed is also suppressed in the frequency recovery stage; and droop control cannot respond correctly when the frequency changes rapidly, which easily causes excessive frequency regulation. How to participate in the rapid regulation of frequency in complex power grids based on ESSs is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present invention provides a method, device, equipment and medium for determining the discharge time of a power grid energy storage system, which can determine the discharge time of the energy storage system participating in frequency regulation when the frequency of the power grid system drops, thereby reducing the impact of frequency fluctuations on the power grid system.

[0005] According to one aspect of the present invention, a method for determining a discharge time of a power grid energy storage system is provided, the method comprising:

[0006] If it is determined that the frequency change of the power grid system meets the preset frequency drop condition, the predicted power grid frequency of the power grid system at the candidate discharge time is determined based on the time domain analytical expression of the power grid system frequency response; the candidate discharge time is the time when the candidate discharge of the energy storage system starts;

[0007] Determine the lowest frequency of the power grid system after the energy storage system has finished discharging according to the candidate discharge time and the time domain analytical expression of the power grid system frequency response;

[0008] The candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirement is determined as the final discharge time of the energy storage system.

[0009] According to another aspect of the present invention, a device for determining a discharge time of a power grid energy storage system is provided, comprising:

[0010] A predicted grid frequency determination module is used to determine the predicted grid frequency of the grid system at a candidate discharge time based on a time-domain analytical expression of the grid system frequency response if it is determined that the frequency change of the grid system satisfies a preset frequency drop condition; the candidate discharge time is the time when the candidate discharge of the energy storage system starts;

[0011] A minimum frequency determination module, used to determine the minimum frequency of the power grid system after the energy storage system has finished discharging according to the candidate discharge time and the time domain analytical expression of the power grid system frequency response;

[0012] The final discharge time determination module is used to determine the candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirement as the final discharge time of the energy storage system.

[0013] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0014] at least one processor; and

[0015] a memory communicatively connected to the at least one processor; wherein,

[0016] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for determining the discharge time of the grid energy storage system described in any embodiment of the present invention.

[0017] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the method for determining the discharge time of a power grid energy storage system described in any embodiment of the present invention when executed.

[0018] The technical solution of the embodiment of the present application includes: if it is determined that the frequency change of the power grid system meets the preset frequency reduction condition, then the predicted power grid frequency of the power grid system at the candidate discharge time is determined based on the time domain analytical expression of the power grid system frequency response; the candidate discharge time is the time when the candidate discharge of the energy storage system starts; according to the candidate discharge time and the time domain analytical expression of the power grid system frequency response, the lowest frequency of the power grid system after the discharge of the energy storage system is determined; the candidate discharge time when the predicted power grid frequency and the lowest frequency meet the preset frequency requirements is determined as the final discharge time of the energy storage system. This technical solution determines the predicted power grid frequency and the lowest frequency through the time domain analytical expression of the power grid system frequency response, and then determines the candidate discharge time when the two frequencies meet the preset frequency requirements as the final discharge time of the energy storage system, so that the energy storage system can inject power into the power grid system at the final discharge time when the power grid system experiences a frequency reduction, thereby reducing the impact of frequency fluctuations on the power grid system.

[0019] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 is a flow chart of a method for determining the discharge time of a power grid energy storage system provided according to Embodiment 1 of the present application;

[0022] Figure 2 is a flow chart of a method for determining the discharge time of a power grid energy storage system provided in accordance with Embodiment 2 of the present application;

[0023] Figure 3 It is a structural schematic diagram of a device for determining the discharge time of a power grid energy storage system provided according to Embodiment 3 of the present application;

[0024] Figure 4 It is a structural schematic diagram of an electronic device for implementing a method for determining a discharge time of a power grid energy storage system according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first", "second", "target", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0027] Embodiment 1

[0028] Figure 1 A flow chart of a method for determining the discharge time of a power grid energy storage system is provided for the first embodiment of the present application. The embodiment of the present application is applicable to the case where the discharge time of the energy storage system is determined. The method can be executed by a device for determining the discharge time of the power grid energy storage system. The device for determining the discharge time of the power grid energy storage system can be implemented in the form of hardware and / or software. The device for determining the discharge time of the power grid energy storage system can be configured in an electronic device with data processing capabilities. Figure 1 As shown, the method includes:

[0029] S110: If it is determined that the frequency change of the power grid system satisfies a preset frequency drop condition, a predicted power grid frequency of the power grid system at the candidate discharge time is determined based on a time domain analytical expression of the power grid system frequency response.

[0030] The power grid system can be a whole composed of substations and transmission and distribution lines of various voltages in the power grid system. The frequency of the power grid system will fluctuate differently under different circumstances. For example, the start and stop of high-power equipment in industrial production and seasonal changes in residential electricity consumption will cause load fluctuations, which will in turn affect the power grid frequency. For example, during high temperatures in summer, air conditioners and other refrigeration equipment are used in large quantities, power consumption increases significantly, and load fluctuations are large, which may cause the power grid frequency to drop.

[0031] The preset frequency reduction condition reflects the condition for judging that the power grid system has a frequency reduction and requires the energy storage system to perform frequency regulation. The preset frequency reduction condition can be determined based on actual conditions, and the embodiments of the present application do not limit this. For example, if the frequency of the power grid system is lower than a first threshold, it is determined that the frequency change of the power grid system satisfies the preset frequency reduction condition; or, if the frequency of the power grid system decreases by more than a second threshold over a period of time, it is determined that the frequency change of the power grid system satisfies the preset frequency reduction condition.

[0032] In the embodiment of the present application, the time-domain analytical expression of the frequency response of the power grid system reflects the change of the power grid frequency. Its independent variable can be time, and the dependent variable can be the power grid system frequency. The time-domain analytical expression of the frequency response of the power grid system reflects the change of the frequency of the power grid system over time. The candidate discharge time is the time when the candidate discharge of the energy storage system starts. The technical solution needs to determine the final discharge time of the energy storage system. The candidate discharge time can be determined first. If a candidate discharge time meets the subsequent requirements, the candidate discharge time is determined as the final discharge time.

[0033] Specifically, the frequency of the power grid system is continuously monitored. If the frequency change satisfies a preset frequency drop condition (for example, the frequency drop amplitude within a period of time is greater than a second threshold), the predicted power grid frequency of the power grid system at the candidate discharge time is determined based on the time domain analytical expression of the power grid system frequency response, that is, the predicted power grid frequency varies with different candidate discharge times.

[0034] S120, determining the lowest frequency of the power grid system after the energy storage system completes discharging according to the candidate discharge time and the time-domain analytical expression of the power grid system frequency response.

[0035] Specifically, after the candidate discharge time is determined, since the impact of the discharge of the energy storage system on the power grid system can be represented by the time domain analytical expression of the power grid system frequency response, the lowest frequency of the power grid system after the energy storage system discharges can be determined based on the candidate discharge time and the time domain analytical expression of the power grid system frequency response.

[0036] S130, determining the candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirement as the final discharge time of the energy storage system.

[0037] The preset frequency requirement may be a requirement that the frequency of the power grid system is as stable as possible. The preset frequency requirement may be determined based on actual conditions. The setting goal of the preset frequency requirement may be to make the predicted power grid frequency and the minimum frequency as large as possible. The final discharge time is the actual discharge time of the energy storage system, that is, the time when the energy storage system injects power into the power grid system.

[0038] Specifically, the predicted grid frequency and the minimum frequency are determined. Since the predicted grid frequency and the minimum frequency affect each other, that is, the minimum frequency will also change after the predicted grid frequency changes, the candidate discharge time when both meet the preset frequency requirements can be determined as the final discharge time of the energy storage system.

[0039] In an embodiment of the present application, optionally, determining the candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirement as the final discharge time of the energy storage system includes: determining the candidate discharge time when the predicted grid frequency is equal to the minimum frequency as the final discharge time of the energy storage system.

[0040] Specifically, after a frequency drop in the power grid system, also known as a load step, it is necessary to avoid the power grid system's frequency being too low. In this case, the predicted power grid frequency and the minimum frequency can be compared. When the predicted power grid frequency is equal to the minimum frequency, the minimum value of the power grid system's frequency is the highest. The candidate discharge time at this time is determined as the final discharge time of the energy storage system, which has the effect of reducing the fluctuation amplitude of the power grid system's frequency, so that the energy storage system can maximize the use of its own power and prevent unnecessary load shedding and power outages.

[0041] The technical solution of the embodiment of the present application includes: if it is determined that the frequency change of the power grid system meets the preset frequency reduction condition, then the predicted power grid frequency of the power grid system at the candidate discharge time is determined based on the time domain analytical expression of the power grid system frequency response; the candidate discharge time is the time when the candidate discharge of the energy storage system starts; according to the candidate discharge time and the time domain analytical expression of the power grid system frequency response, the lowest frequency of the power grid system after the discharge of the energy storage system is determined; the candidate discharge time when the predicted power grid frequency and the lowest frequency meet the preset frequency requirements is determined as the final discharge time of the energy storage system. This technical solution determines the predicted power grid frequency and the lowest frequency through the time domain analytical expression of the power grid system frequency response, and then determines the candidate discharge time when the two frequencies meet the preset frequency requirements as the final discharge time of the energy storage system, so that the energy storage system can inject power into the power grid system at the final discharge time when the power grid system experiences a frequency reduction, thereby reducing the impact of frequency fluctuations on the power grid system.

[0042] Embodiment 2

[0043] Figure 2 This is a flow chart of a method for determining the discharge time of a power grid energy storage system provided in Embodiment 2 of the present application. The embodiment of the present application is optimized based on the above embodiment.

[0044] like Figure 2 As shown, the method of the embodiment of the present application specifically includes the following steps:

[0045] S210: If it is determined that a load step occurs in the frequency change of the power grid system, a predicted power grid frequency of the power grid system at the candidate discharge time is determined based on a time domain analytical expression of the power grid system frequency response.

[0046] In an embodiment of the present application, optionally, the time-domain analytical expression of the power grid system frequency response is a piecewise function, which includes three sub-functions: the independent variable range of the first sub-function is a time less than or equal to the time when the energy storage system starts discharging, the independent variable range of the second sub-function is a time greater than the time when the energy storage system starts discharging and less than or equal to the end time of the energy storage system discharging, and the independent variable range of the third sub-function is a time greater than the end time of the energy storage system discharging.

[0047] Specifically, in the time-domain analytical expression of the power grid system frequency response, the time when the load step occurs in the power grid system can be set to zero, that is, in the first sub-function, since it reflects the frequency response of the power grid system just after the load step occurs, its frequency value decreases with the movement of time until the time when the energy storage system starts to discharge. The independent variable range of the second sub-function is a time greater than the time when the energy storage system starts to discharge and less than or equal to the time when the energy storage system starts to discharge. In this stage, since the energy storage system injects power into the power grid system, the power of the power grid system increases compared to the time when the energy storage system starts to discharge. The third sub-function corresponds to the third stage, that is, the frequency change after the energy storage system finishes discharging. Since the energy storage system ends discharging, the frequency of the power grid system may decrease, but since the power of the generator begins to increase, the frequency of the power grid system will rebound after the decrease.

[0048] In the embodiment of the present application, optionally, the process of determining the first sub-function includes:

[0049] The time domain response expression of the frequency of the power grid system to the load step is determined as the first sub-function.

[0050] Specifically, since the first sub-function corresponds to the frequency response of the power grid system after a load step occurs, and the energy storage system and the engine have not yet participated in power injection, the first sub-function can be determined based on the time domain response expression of the power grid system frequency to the load step.

[0051] The process of determining the second sub-function includes:

[0052] The second sub-function is determined according to a time-domain response expression of the frequency of the power grid system to a load step and a time-domain response expression of the power grid system to a step of the energy storage system.

[0053] Specifically, the second sub-function corresponds to the stage after power injection into the energy storage system. At this time, it is only affected by the energy storage system and the load step that occurred previously. Therefore, the second sub-function can be determined based on the time domain response expression of the power grid system's frequency to the load step and the time domain response expression of the power grid system to the energy storage system step.

[0054] The process of determining the third sub-function includes:

[0055] The third sub-function is determined according to a time-domain response expression of the frequency of the power grid system to a load step and a time-domain response expression of the power grid system to a step of the energy storage system.

[0056] Specifically, the third sub-function corresponds to the stage after the power injection of the energy storage system is completed, and can also be determined according to the time domain response expression of the power grid system frequency to the load step and the time domain response expression of the power grid system to the energy storage system step.

[0057] In the embodiment of the present application, optionally, the time domain analytical expression of the power grid system frequency response is as follows:

[0058]

[0059] Where, f(t) is the time domain analytical expression of the power grid system frequency response, f L (t) is the time domain response expression of the power grid system frequency to the load step, f s0 (t) = f s (t-t0), f s1 (t) = f s (t-t1), f s (t) is the time domain response expression of the power grid system to the step of the energy storage system, t0 is the start discharge time of the energy storage system, and t1 is the end discharge time of the energy storage system.

[0060] In the embodiment of the present application, optionally, the time domain response expression of the frequency of the power grid system to the load step is determined according to the following formula:

[0061]

[0062] Among them, L -1 {} is the inverse Laplace transform, H is the equivalent inertia time constant of the power grid system, s is the complex variable in the inverse Laplace transform, D is the equivalent damping coefficient of the power grid system, G sys (s) is the equivalent frequency response transfer function of the power grid system, p L is the power of the power grid system; where 2Hs is 2×H×s, and the s here is not a superscript.

[0063] The time domain response expression of the power grid system to the energy storage system step is as follows:

[0064]

[0065] Among them, p s The injected power of the energy storage system participating in frequency response.

[0066] Furthermore, G. sys (s) is the equivalent frequency response transfer function of the power grid system;

[0067]

[0068] Among them, G i (s) is the low-order universal speed control system transfer function of generator i, i is the generator number, G j (s) is the universal frequency response model transfer function of the new energy station j, and j is the number of the new energy station. G is the number of generators, N is the number of generators and new energy stations. α is the corresponding coefficient.

[0069] S220, determining the lowest frequency of the power grid system after the energy storage system has finished discharging according to the candidate discharge time and the time-domain analytical expression of the power grid system frequency response.

[0070] In an embodiment of the present application, optionally, the process of determining the minimum frequency includes: calculating the derivative of the third sub-function of the time-domain analytical expression of the power grid system frequency response; determining the independent variable when the derivative is zero as the target time point; and determining the value of the time-domain analytical expression of the power grid system frequency response at the target time point as the minimum frequency.

[0071] Before calculating the derivative of the third sub-function of the time-domain analytical expression of the power grid system frequency response, the candidate discharge time can be substituted into the time-domain analytical expression of the power grid system frequency response to obtain the time-domain analytical expression of the power grid system frequency response with the candidate discharge time determined, and then the derivative of the third sub-function of the time-domain analytical expression of the power grid system frequency response is calculated, and then the expression of the lowest frequency can be expressed by the function of the candidate discharge time.

[0072] S230: Determine the candidate discharge time when the predicted grid frequency is equal to the minimum frequency as the final discharge time of the energy storage system.

[0073] Exemplarily, t=t0 is substituted into the time domain analytical expression of the power grid system frequency response to obtain the predicted power grid frequency: f0;

[0074] By solving the derivative of the third sub-function to be zero, the target time point t2 is obtained;

[0075] Substitute t=t2 into the third sub-function to calculate the value of the lowest frequency f2 after the energy storage system injects power, that is, formula f2;

[0076] The candidate discharge time when the predicted grid frequency f0 is equal to the minimum frequency f2 is determined as the final discharge time of the energy storage system.

[0077] It should be noted that since both f0 and f2 are functions of the power injection time t0, that is, t2 can be converted into a function of t0, the final discharge time t0 can be determined when the two equations are equal.

[0078] The technical solution of the embodiment of the present application determines the predicted grid frequency through the time-domain analytical expression of the grid system frequency response. When the candidate discharge time is determined, the minimum frequency is determined through the time-domain analytical expression of the grid system frequency response, and then the candidate discharge time when the predicted grid frequency is equal to the minimum frequency is determined as the final discharge time of the energy storage system, so that after the energy storage system injects power into the grid system at the final discharge time, the lowest point of the grid system frequency is the highest, that is, the frequency fluctuation of the grid system is reduced, and the safe and stable operation of the power system is guaranteed.

[0079] Embodiment 3

[0080] Figure 3 This is a schematic diagram of the structure of a device for determining the discharge time of a power grid energy storage system provided in the third embodiment of the present application. The device can execute the method for determining the discharge time of a power grid energy storage system provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method. Figure 3 As shown, the device comprises:

[0081] A predicted grid frequency determination module 310 is used to determine the predicted grid frequency of the grid system at a candidate discharge time based on a time domain analytical expression of the grid system frequency response if it is determined that the frequency change of the grid system satisfies a preset frequency drop condition; the candidate discharge time is a candidate discharge start time of the energy storage system;

[0082] A minimum frequency determination module 320, configured to determine the minimum frequency of the power grid system after the energy storage system has finished discharging according to the candidate discharge time and the time domain analytical expression of the power grid system frequency response;

[0083] The final discharge time determination module 330 is used to determine the candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirement as the final discharge time of the energy storage system.

[0084] The technical solution of the embodiment of the present application includes: a predicted grid frequency determination module 310, which is used to determine the predicted grid frequency of the grid system at the candidate discharge time based on the grid system frequency response time domain analytical formula if it is determined that the frequency change of the grid system meets the preset frequency reduction condition; the candidate discharge time is the time when the candidate discharge of the energy storage system starts; a minimum frequency determination module 320, which is used to determine the minimum frequency of the grid system after the discharge of the energy storage system ends according to the candidate discharge time and the grid system frequency response time domain analytical formula; a final discharge time determination module 330, which is used to determine the candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirements as the final discharge time of the energy storage system. This technical solution determines the predicted grid frequency and the minimum frequency through the grid system frequency response time domain analytical formula, and then determines the candidate discharge time when the two frequencies meet the preset frequency requirements as the final discharge time of the energy storage system, so that the energy storage system can inject power into the grid system at the final discharge time when the grid system experiences a frequency reduction, thereby reducing the impact of frequency fluctuations on the grid system.

[0085] In the embodiment of the present application, optionally, the final discharge time determination module 330 includes:

[0086] The final discharge time determination unit is used to determine the candidate discharge time when the predicted grid frequency is equal to the minimum frequency as the final discharge time of the energy storage system.

[0087] In an embodiment of the present application, optionally, the time-domain analytical expression of the power grid system frequency response is a piecewise function, which includes three sub-functions: the independent variable range of the first sub-function is a time less than or equal to the time when the energy storage system starts discharging, the independent variable range of the second sub-function is a time greater than the time when the energy storage system starts discharging and less than or equal to the end time of the energy storage system discharging, and the independent variable range of the third sub-function is a time greater than the end time of the energy storage system discharging.

[0088] In the embodiment of the present application, optionally, the device further includes: a minimum frequency determination module, specifically including:

[0089] A derivative calculation unit, used to calculate the derivative of the third sub-function of the time-domain analytical expression of the power grid system frequency response;

[0090] A target time point determination unit, used for determining the independent variable when the derivative is zero as the target time point;

[0091] The minimum frequency determination unit is used to determine the value of the time-domain analytical expression of the power grid system frequency response at a target time point as the minimum frequency.

[0092] In the embodiment of the present application, optionally, the device further includes: a first sub-function determination module, specifically configured to:

[0093] Determine the time domain response expression of the frequency of the power grid system to the load step as the first sub-function;

[0094] The second sub-function determines the module, which is specifically used for:

[0095] Determining the second sub-function according to a time-domain response expression of the frequency of the power grid system to a load step and a time-domain response expression of the power grid system to a step of the energy storage system;

[0096] The third sub-function determines the module, which is specifically used for:

[0097] The third sub-function is determined according to a time-domain response expression of the frequency of the power grid system to a load step and a time-domain response expression of the power grid system to a step of the energy storage system.

[0098] In the embodiment of the present application, optionally, the time domain analytical expression of the power grid system frequency response is as follows:

[0099]

[0100] Where, f(t) is the time domain analytical expression of the power grid system frequency response, f L (t) is the time domain response expression of the power grid system frequency to the load step, f s0 (t) = f s (t-t0), f s1 (t) = f s (t-t1), f s (t) is the time domain response expression of the power grid system to the step of the energy storage system, t0 is the start discharge time of the energy storage system, and t1 is the end discharge time of the energy storage system.

[0101] In the embodiment of the present application, optionally, the time domain response expression of the frequency of the power grid system to the load step is determined according to the following formula:

[0102]

[0103] Among them, L -1 {} is the inverse Laplace transform, H is the equivalent inertia time constant of the power grid system, s is the complex variable in the inverse Laplace transform, D is the equivalent damping coefficient of the power grid system, G sys (s) is the equivalent frequency response transfer function of the power grid system, p L is the power of the grid system;

[0104] The time domain response expression of the power grid system to the energy storage system step is as follows:

[0105]

[0106] Among them, ps The injected power of the energy storage system participating in frequency response.

[0107] A device for determining the discharge time of a power grid energy storage system provided in an embodiment of the present application can execute a method for determining the discharge time of a power grid energy storage system provided in any embodiment of the present invention, and has functional modules and beneficial effects corresponding to the execution method.

[0108] Embodiment 4

[0109] Figure 4 A schematic diagram of the structure of an electronic device 10 that can be used to implement an embodiment of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0110] like Figure 4 As shown, the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0111] A number of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0112] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as a method for determining the discharge time of a grid energy storage system.

[0113] In some embodiments, the method for determining the discharge time of the grid energy storage system may be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the method for determining the discharge time of the grid energy storage system described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to execute the method for determining the discharge time of the grid energy storage system in any other appropriate manner (e.g., by means of firmware).

[0114] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0115] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0116] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0117] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0118] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0119] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0120] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0121] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the discharge time of a power grid energy storage system, characterized in that: include: If it is determined that the frequency change of the power grid system meets the preset frequency drop condition, the predicted power grid frequency of the power grid system at the candidate discharge time is determined based on the time domain analytical expression of the power grid system frequency response; the candidate discharge time is the time when the candidate discharge of the energy storage system starts; Determine the lowest frequency of the power grid system after the energy storage system has finished discharging according to the candidate discharge time and the time domain analytical expression of the power grid system frequency response; The candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirement is determined as the final discharge time of the energy storage system.

2. The method according to claim 1, characterized in that The step of determining the candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirement as the final discharge time of the energy storage system includes: The candidate discharge time when the predicted grid frequency is equal to the minimum frequency is determined as the final discharge time of the energy storage system.

3. The method according to claim 1, characterized in that The time-domain analytical expression of the power grid system frequency response is a piecewise function, which includes three sub-functions: the independent variable range of the first sub-function is a time less than or equal to the time when the energy storage system starts discharging, the independent variable range of the second sub-function is a time greater than the time when the energy storage system starts discharging and less than or equal to the end time of the energy storage system discharging, and the independent variable range of the third sub-function is a time greater than the end time of the energy storage system discharging.

4. The method according to claim 3, characterized in that The process of determining the minimum frequency includes: Calculating the derivative of the third sub-function of the time-domain analytical expression of the power grid system frequency response; The independent variable when the derivative is zero is determined as the target time point; The value of the time-domain analytical expression of the power grid system frequency response at the target time point is determined as the lowest frequency.

5. The method according to claim 3, characterized in that: The process of determining the first sub-function includes: Determine the time domain response expression of the frequency of the power grid system to the load step as the first sub-function; The process of determining the second sub-function includes: Determining the second sub-function according to a time-domain response expression of the frequency of the power grid system to a load step and a time-domain response expression of the power grid system to a step of the energy storage system; The process of determining the third sub-function includes: The third sub-function is determined according to a time-domain response expression of the frequency of the power grid system to a load step and a time-domain response expression of the power grid system to a step of the energy storage system.

6. The method according to claim 1, characterized in that The time domain analytical expression of the power grid system frequency response is as follows: Where, f(t) is the time domain analytical expression of the power grid system frequency response, f L (t) is the time domain response expression of the power grid system frequency to the load step, f s0 (t) = f s (t-t0), f s1 (t) = f s (t-t1), f s (t) is the time domain response expression of the power grid system to the step of the energy storage system, t0 is the start discharge time of the energy storage system, and t1 is the end discharge time of the energy storage system.

7. The method according to claim 6, characterized in that The time domain response expression of the power grid system frequency to the load step is determined according to the following formula: Among them, L -1 {} is the inverse Laplace transform, H is the equivalent inertia time constant of the power grid system, s is the complex variable in the inverse Laplace transform, D is the equivalent damping coefficient of the power grid system, G sys (s) is the equivalent frequency response transfer function of the power grid system, p L is the power of the grid system; The time domain response expression of the power grid system to the energy storage system step is as follows: Among them, p s The injected power of the energy storage system participating in frequency response.

8. A device for determining the discharge time of a power grid energy storage system, characterized in that: include: A predicted grid frequency determination module is used to determine the predicted grid frequency of the grid system at a candidate discharge time based on a time-domain analytical expression of the grid system frequency response if it is determined that the frequency change of the grid system satisfies a preset frequency drop condition; the candidate discharge time is the time when the candidate discharge of the energy storage system starts; A minimum frequency determination module, used to determine the minimum frequency of the power grid system after the energy storage system has finished discharging according to the candidate discharge time and the time domain analytical expression of the power grid system frequency response; The final discharge time determination module is used to determine the candidate discharge time when the predicted grid frequency and the minimum frequency meet the preset frequency requirement as the final discharge time of the energy storage system.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for determining the discharge time of the grid energy storage system according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the method for determining the discharge time of the power grid energy storage system according to any one of claims 1 to 7 when executed.

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