A wind-storage combined frequency regulation control method considering the secondary frequency drop of power system

Abstract

The present invention relates to a wind-storage joint frequency regulation control method taking into account the secondary drop of the power system frequency, comprising: establishing a frequency response model in a multi-machine power system containing wind turbines, obtaining a system frequency response characteristic expression under power disturbance, and then obtaining the maximum frequency change rate and the maximum frequency deviation of the primary drop; when the wind turbine exits the frequency regulation and enters the speed recovery stage, establishing the frequency response characteristics of the secondary drop system under unbalanced power, and obtaining the maximum frequency deviation of the secondary drop; using the maximum frequency deviation of the primary and secondary drops, the maximum frequency change rate and the charge state of the energy storage itself, according to the fuzzy control strategy, the energy storage frequency regulation control parameters are obtained to realize the wind-storage joint frequency regulation control. Compared with the prior art, the present invention realizes the complementary advantages of wind turbines and energy storage, reduces the depth of the secondary frequency drop and the probability of its occurrence, improves the frequency response characteristics of the system, and ensures the safe and stable operation of the power system.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a wind-storage combined frequency regulation control method taking into account a secondary drop in the frequency of a power system. Background Art

[0002] With the proposal of "carbon peak" and "carbon neutrality", the proportion of new energy connected to the grid, represented by wind power, continues to increase, gradually replacing traditional fossil energy. However, its own volatility and intermittent characteristics have significantly affected the safe and stable operation of the power grid. The active support capacity of the power grid is insufficient. In the event of high power loss or system failure, it is very easy to induce frequency failures of the entire network. The large-scale access of wind power has brought huge challenges to the safe and stable operation of the power system.

[0003] At present, the methods for wind turbines to participate in the primary frequency regulation of the power grid can be mainly divided into two categories: rotor kinetic energy control and power reserve control. This application focuses on the introduction based on rotor kinetic energy control. The principle of rotor kinetic energy control is to provide active support by releasing the kinetic energy stored in the wind turbine. A frequency regulation control module with a frequency change signal is added on the basis of MPPT control, so that the wind turbine can respond to changes in the frequency of the power grid. When the frequency of the power grid drops, the output power instruction can be corrected by adjusting the control strategy to provide short-term active support. Its frequency regulation method is mainly divided into virtual inertia control, droop control and comprehensive inertia control. The wind turbine based on the above control will release the rotor kinetic energy and reduce the speed during the frequency support process. When the rotor reaches the minimum speed limit, it can no longer release kinetic energy to support the system frequency. Instead, it needs to absorb power from the power grid to increase the speed, which may cause the frequency to drop twice. The energy storage system has accurate, fast and flexible power response capabilities, which is suitable for joint deployment with wind farms. It can improve the controllability of wind farm output, so that it has the ability to actively participate in power grid frequency regulation. At present, most studies control wind turbines and energy storage as separate frequency regulation resources, and wind turbines and energy storage only respond to frequency regulation according to their respective set frequency regulation coefficients. At the same time, overcharging or over-discharging of energy storage systems is not conducive to the sustainability and effectiveness of wind-storage joint frequency regulation. Therefore, in order to provide effective frequency support for the system and meet the actual frequency regulation needs of the system, it is necessary to comprehensively consider the entire frequency dynamic process including primary and secondary drops, while taking into account the charge state of energy storage, and design a reasonable and effective wind-storage joint frequency regulation control method. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a wind-storage combined frequency regulation control method taking into account the secondary drop of the power system frequency.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A wind power storage combined frequency regulation control method taking into account the secondary drop of power system frequency, comprising:

[0007] A frequency response model is established in a multi-machine power system including wind turbines, so that conventional synchronous units and wind turbines can jointly participate in a frequency modulation after the system frequency drops, and the system frequency response characteristic expression under power disturbance is obtained, and then the maximum frequency change rate and the maximum frequency deviation of a drop are obtained;

[0008] When the fan exits frequency modulation and enters the speed recovery stage, the frequency response characteristics of the secondary frequency drop system under unbalanced power are established to obtain the maximum frequency deviation of the secondary drop;

[0009] The maximum frequency deviation of the primary and secondary drops, the maximum frequency change rate and the charge state of the energy storage are used to obtain the energy storage frequency regulation control parameters according to the fuzzy control strategy to achieve wind and storage joint frequency regulation control; the energy storage device adaptively adjusts the frequency regulation control parameters according to the frequency operation state of the power system to reduce the depth of the secondary frequency drop and the probability of its occurrence;

[0010] The method of obtaining the energy storage frequency modulation control parameters according to the fuzzy control strategy specifically includes: using the energy storage's own charge state, frequency deviation and frequency change rate as the input of the fuzzy controller, using the virtual inertia and droop coefficient of the energy storage participating in the frequency modulation as the output of the fuzzy controller, designing the domain and membership function of the fuzzy controller's input and output variables, establishing a fuzzy rule table, and obtaining the energy storage frequency modulation control parameters according to the fuzzy rule table;

[0011] The basic domain of frequency deviation is [-1Hz, 1Hz], and the corresponding fuzzy subset is {NB, NS, ZO, PS, PB}; the basic domain of frequency deviation rate is [-0.4Hz, 0.4Hz], and the corresponding fuzzy subset is {NB, NS, ZO, PS, PB}; the basic domain of energy storage's own state of charge is [0.15, 0.95], and the corresponding fuzzy subset is {VS, S, RS, M, RB, B, VB}; the basic domain of energy storage frequency control parameters is [0, 5], and the corresponding fuzzy subset is {NB, S, NS, ZO, PS, B, PB}; the fuzzy rule table is established with the above domains, as shown in Table 1 below:

[0012] Table 1

[0013]

[0014]

[0015] Among them, SOC is the state of charge of the energy storage itself, Δf is the frequency deviation, and df / dt is the frequency change rate;

[0016] When the energy storage battery's own charge state is used as the input of the fuzzy controller, the energy storage battery's own charge state is set as a normal value in the range of 0.15 to 0.95, and a value below 0.15 or above 0.95 is set as an abnormal operating state of the energy storage battery.

[0017] Preferably, the system frequency response characteristic expression is:

[0018] f(t)=Me αt cos(ωt+θ)+C

[0019]

[0020] Where t is time, T J is the inertia time constant of the conventional synchronous unit, T G K is the time constant of the speed regulator action. W1 is the droop coefficient, K W2 is the virtual inertia coefficient, K G The unit power adjustment is ΔP L is the disturbance load.

[0021] Preferably, the inertia time constant T of the conventional synchronous unit J The following conventional synchronous unit rotor motion equation is satisfied:

[0022]

[0023] in, is the frequency change rate, P G0 is the initial output of the conventional synchronous unit, ΔP G The additional power generated by the conventional synchronous unit, P w0 is the initial output of the wind turbine, ΔP w is the additional power generated by the wind turbine, P L0 The original load of the system.

[0024] Preferably, the time constant T of the speed regulator action is G Satisfies the following expression:

[0025]

[0026] Among them, ΔP G is the additional power generated by the conventional synchronous unit, and Δf is the frequency deviation.

[0027] Preferably, the expression of the maximum frequency change rate is:

[0028]

[0029] Preferably, the expression of the maximum frequency deviation of a drop is:

[0030]

[0031] in,

[0032] Preferably, the expression of the maximum frequency deviation of the secondary drop is:

[0033]

[0034] Among them, f off is the moment when the fan exits frequency regulation, ΣΔP d is the total unbalanced power of the system.

[0035] Preferably, the total unbalanced power of the system is:

[0036]

[0037] in, is the fan response power, is the mechanical power of the fan.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] 1. Aiming at the problem of secondary frequency drop in power system, the present invention constructs a wind-storage joint frequency regulation control strategy that combines energy storage with wind power's own frequency regulation. While realizing active support of the power system frequency by the wind farm, an energy storage device that adaptively adjusts the frequency regulation control parameters according to the power system frequency operating state can be added to realize the complementary advantages of wind turbines and energy storage, so as to reduce the frequency deterioration problem that may be caused by switching the operating state of wind turbines, reduce the depth of secondary frequency drop and the probability of its occurrence, improve the frequency response characteristics of the system, and ensure the safe and stable operation of the power system.

[0040] 2. The present invention can adjust the active output of battery energy storage participating in frequency modulation according to the changes in system frequency, fully configure the output parameters of virtual inertia control and virtual droop control, and optimize the combination of the two to achieve the optimal frequency modulation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a method flow chart of an embodiment of the present invention;

[0042] Figure 2 is a fan working state switching curve diagram according to an embodiment of the present invention;

[0043] Figure 3 is a topological structure diagram of a system example of an embodiment of the present invention;

[0044] Figure 4 It is a frequency simulation comparison diagram of three events in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0046] In a multi-machine power system containing wind turbines, when the wind turbines use rotor kinetic energy control to participate in system frequency regulation, when the rotor reaches the minimum speed limit, it cannot continue to release kinetic energy to support the system frequency. There is a difference between mechanical power and electromagnetic power, which will cause a secondary drop in frequency. With the rapid development of new energy represented by wind power generation, the risk of secondary drop in power system frequency has increased, threatening frequency stability. Energy storage can provide effective frequency support for the system by utilizing its technical characteristics of fast response, flexible control, and stable operation.

[0047] like Figure 1 As shown, the present invention proposes a wind-storage combined frequency regulation control method taking into account the secondary drop of the power system frequency, aiming to reduce the risk of secondary drop of the system frequency caused by the speed recovery stage during the frequency regulation process of the double-fed wind turbine. The method includes:

[0048] A frequency response model is established in a multi-machine power system including wind turbines, so that conventional synchronous units and wind turbines can jointly participate in a frequency modulation after the system frequency drops, and the system frequency response characteristic expression under power disturbance is obtained, and then the maximum frequency change rate and the maximum frequency deviation of a drop are obtained;

[0049] When the fan exits frequency modulation and enters the speed recovery stage, the frequency response characteristics of the secondary frequency drop system under unbalanced power are established to obtain the maximum frequency deviation of the secondary drop;

[0050] By utilizing the maximum frequency deviation of the primary and secondary drops, the maximum frequency change rate and the charge state of the energy storage itself, the energy storage frequency regulation control parameters are obtained according to the fuzzy control strategy to achieve wind-storage joint frequency regulation control.

[0051] This method can improve the frequency response characteristics of the system. While realizing the active support of the wind farm for the power system frequency, it can also add an energy storage device that adaptively adjusts the frequency control parameters according to the power system frequency operating status, effectively suppressing the risk of secondary drop in system frequency caused by the speed recovery stage when the wind turbine sets switch operating states, and effectively improving the safety and stability of the system frequency.

[0052] When the system frequency drops, conventional synchronous units and wind turbines jointly participate in a frequency regulation after detecting the frequency deviation. The rotor motion equation for conventional synchronous units is established:

[0053]

[0054] in, is the frequency change rate, T J is the inertia time constant of the conventional synchronous unit, P G0 is the initial output of the conventional synchronous unit, ΔP G The additional power generated by the conventional synchronous unit, P w0 is the initial output of the wind turbine, ΔP w is the additional power generated by the wind turbine, P L0 is the original load of the system, ΔP L is the disturbance load.

[0055] The speed regulator action is simplified to a first-order inertia link, and its mathematical model is:

[0056]

[0057] Among them, T G is the time constant of the speed regulator action, ΔP G is the additional power of the conventional synchronous unit, Δf is the frequency deviation, K G Adjust the power for the unit.

[0058] The power increment of the wind turbine generator system participating in frequency regulation using comprehensive inertia control is:

[0059]

[0060] Among them, K W1 is the droop coefficient, K W2 is the virtual inertia coefficient.

[0061] Combining the above formula, we can get the second-order differential equation:

[0062]

[0063] Substitute the initial conditions:

[0064]

[0065] Where f0 is the initial frequency per unit value.

[0066] The system frequency response characteristic expression is obtained as follows:

[0067] f(t)=Me αt cos(ωt+θ)+C (2)

[0068]

[0069]

[0070] Where t is time.

[0071] Taking the system frequency deviation Δf and the frequency change rate RoCoF as the main frequency indicators, the maximum frequency deviation Δf of a drop is further obtained from the obtained frequency response characteristic expression nadir1 and the maximum frequency change rate RoCoF max By taking the derivative of equation (1) and setting time t = 0, we can get the expression of the maximum frequency change rate of the power system:

[0072]

[0073] By taking the derivative of equation (2) and setting the frequency change rate df / dt = 0, the expression of the maximum frequency deviation of a drop is obtained:

[0074]

[0075] in,

[0076] After the fan exits frequency modulation and enters speed recovery, the system unbalanced power changes, and the unbalanced power ∑ΔP is established. d The frequency response characteristics of the secondary frequency drop system under the condition of frequency drop are studied, and the system frequency deviation Δf is taken as the main indicator, and the expression of the maximum frequency deviation of the secondary drop is obtained.

[0077] The fan working state switching curve is as follows: Figure 2 As shown, where ω r is the wind turbine speed, and P is the wind turbine output power. The wind turbine first works in the MPPT operating state. When the wind turbine participates in the system frequency adjustment, if the frequency drops outside the frequency modulation dead zone, the wind turbine frequency response control strategy is triggered, the wind turbine responds to frequency fluctuations, the electromagnetic power changes from point A to point B', the rotor speed drops to release the rotor kinetic energy, and gradually decreases with the frequency deviation. The additional power gradually decreases with the decrease in frequency change, and it runs step by step along B'C. For a doubly fed asynchronous wind turbine, the minimum value of the wind rotor speed is generally 0.7pu. If the rotor kinetic energy is excessively released and the wind turbine reaches the lowest speed point, the rotor speed recovery strategy will be triggered, forcing it to run along CDE'. When the rotor speed recovers, the wind turbine resumes the MPPT operating state. When the wind speed is v2, after the wind turbine exits the frequency modulation and enters the speed recovery stage, the system unbalanced power changes as follows:

[0078]

[0079] Among them, ∑ΔP d is the total unbalanced power of the system, is the fan response power, is the mechanical power of the fan, The power absorbed by the fan when switching operating states.

[0080] Therefore, the maximum frequency deviation of the secondary drop is Δf nadir2 The expression is:

[0081]

[0082] Among them, f off The moment when the fan exits frequency regulation.

[0083] The overall frequency response characteristics of the system under a certain load disturbance are obtained through the above process. The energy storage frequency regulation control parameters obtained according to the fuzzy control strategy include:

[0084] The energy storage's own state of charge SOC and frequency deviation Δf, df / dt are used as the input of the fuzzy controller, and the virtual inertia and droop coefficient K of the energy storage participating in frequency modulation are used as the input of the fuzzy controller. d , K p For the output of the fuzzy controller, the domain and membership function of the input and output variables of the fuzzy controller are designed, a fuzzy rule table is established, and the energy storage frequency modulation control parameters are obtained according to the fuzzy rule table.

[0085] When the energy storage battery SOC is used as the input of the fuzzy controller, the SOC in the range of 0.15 to 0.95 is set as the normal value, and the SOC below 0.15 or above 0.95 is set as the abnormal operating state of the energy storage battery. The basic domain of the frequency deviation is [-1Hz, 1Hz], and the corresponding fuzzy subset is {NB, NS, ZO, PS, PB}; the basic domain of the frequency deviation rate is [-0.4Hz, 0.4Hz], and the corresponding fuzzy subset is {NB, NS, ZO, PS, PB}; the basic domain of the energy storage state of charge SOC is [0.15, 0.95], and the corresponding fuzzy subset is {VS, S, RS, M, RB, B, VB}, and the basic domain of the energy storage frequency modulation control parameter is [0, 5], and the corresponding fuzzy subset is {NB, S, NS, ZO, PS, B, PB}. The fuzzy rule table is established with the above domain, as shown in Table 1.

[0086] Table 1 Fuzzy control rules table

[0087]

[0088]

[0089] According to the above fuzzy control rule table, the virtual inertia and K of energy storage frequency regulation control parameters under dual input of fuzzy control strategy are obtained. d , K p The value of .

[0090] Example

[0091] This example uses a two-region power system with wind turbines and energy storage to verify the effectiveness of the method of the present invention. The topology of the example system used in this example is shown in the attached figure. Figure 3 As shown in the figure, the capacities of synchronous machines G1, G2, and G3 are 200MVA, 100MVA, and 100MVA respectively. The prime movers are all steam turbines. The DFIG capacity of the double-fed wind turbine is 80MVA, and the battery energy storage capacity is 8MVA. Build a model in Simulink simulation software and export the required data to MATLAB for data processing and calculation.

[0092] The verification idea is as follows: set load disturbance events in different simulation environments, and obtain the system maximum frequency change rate RoCoF under a certain load disturbance according to formulas (3) and (4): max and the maximum frequency deviation of a drop Δf nadir1 According to formula (5), the maximum frequency deviation Δf of the secondary drop of the system is obtained: nadir2 Then, the virtual inertia and droop coefficient K of energy storage participating in frequency modulation are obtained through Table 1. d , K p Finally, the effectiveness of this method is verified by the degree of the secondary drop depth in the frequency curve obtained by simulation.

[0093] Example setting: Set a 30MW load disturbance at simulation t=70s

[0094] Event 1: This is carried out in a two-region power system where the capacities of synchronous machines G1, G2, and G3 are 200MVA, 100MVA, and 100MVA respectively, and the capacity of the doubly-fed wind turbine DFIG is 80MVA, assuming that the energy storage does not provide active output.

[0095] Event 2: This event is carried out in a two-region power system where the capacities of synchronous machines G1, G2, and G3 are 200MVA, 100MVA, and 100MVA respectively, the DFIG capacity of the doubly-fed wind turbine generator is 80MVA, and the battery energy storage capacity is 8MVA. It is assumed that the energy storage adopts the traditional fixed coefficient method control strategy to participate in frequency regulation.

[0096] Event 3: It is carried out in a two-region power system where the capacities of synchronous machines G1, G2, and G3 are 200MVA, 100MVA, and 100MVA respectively, the capacity of the doubly-fed wind turbine DFIG is 80MVA, and the battery energy storage capacity is 8MVA. It is assumed that the energy storage adopts the adaptive parameter control strategy of the present invention to participate in frequency regulation.

[0097] The above example sets up three different simulation environments, and compares the energy storage using adaptive parameter control strategy (event 3) with the energy storage not participating in frequency modulation (event 1) and the energy storage using traditional fixed coefficient control strategy (event 2) to verify the effectiveness of the control method of the present invention. Figure 4 As shown, during the first frequency drop, the lowest point of the system frequency is 49.78Hz when the energy storage does not participate in the frequency modulation, and the lowest point of the system frequency is 49.81Hz when the traditional fixed coefficient method is used for control, and the adaptive coefficient control strategy of the present invention can increase the lowest point of the system frequency to 49.85Hz; during the second frequency drop, the lowest point of the system frequency is 49.71Hz when the energy storage does not participate in the frequency modulation, and the lowest point of the system frequency is 49.77Hz when the traditional fixed coefficient method is used for control, and the adaptive coefficient control strategy of the present invention can increase the lowest point of the system frequency to 49.93Hz. This is because the present invention can adjust the active output of the battery energy storage participating in the frequency modulation according to the changes in the system frequency, fully configure the output parameters of the virtual inertia control and the virtual droop control, and optimize the combination of the two to achieve the optimal frequency modulation effect.

[0098] It can be seen from the above embodiments that this method can make full use of the energy storage output to provide frequency support for the system, alleviate the problem of secondary frequency drop caused by the wind turbines participating in the frequency regulation process, and has good practical value.

[0099] It should be noted that the present application can be implemented in software and / or a combination of software and hardware, for example, can be implemented using an application specific integrated circuit (ASIC), a general purpose computer or any other similar hardware device. In one embodiment, the software program of the present application can be executed by a processor to implement the steps or functions described above. Similarly, the software program of the present application (including relevant data structures) can be stored in a computer-readable recording medium, for example, a RAM memory, a magnetic or optical drive or a floppy disk and similar devices. In addition, some steps or functions of the present application can be implemented using hardware, for example, as a circuit that cooperates with a processor to perform each step or function.

[0100] In a typical configuration of the present application, the terminal and the network device each include one or more processors (CPU), input / output interface, network interface and memory.

[0101] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0102] Computer readable media include permanent and non-permanent, removable and non-removable media, and can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include non-transitory media such as modulated data signals and carrier waves.

[0103] In addition, a part of the present application may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present application through the operation of the computer. The program instruction for calling the method of the present application may be stored in a fixed or removable recording medium, and / or transmitted through a data stream in a broadcast or other signal-bearing medium, and / or stored in a working memory of a computer device that runs according to the program instruction. Here, according to an embodiment of the present application, a device is included, the device including a memory for storing computer program instructions and a processor for executing program instructions, wherein, when the computer program instruction is executed by the processor, the device is triggered to run the method and / or technical solution based on the aforementioned multiple embodiments according to the present application.

[0104] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic features of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present application is limited by the attached claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the present application. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices stated in the device claim can also be implemented by one unit or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

[0105] The preferred specific embodiments of the present application are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present application without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art based on the concept of the present application through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A wind power storage combined frequency regulation control method taking into account the secondary drop of power system frequency, characterized in that: include: A frequency response model is established in a multi-machine power system including wind turbines, so that conventional synchronous units and wind turbines can jointly participate in a frequency modulation after the system frequency drops, and the system frequency response characteristic expression under power disturbance is obtained, and then the maximum frequency change rate and the maximum frequency deviation of a drop are obtained; When the fan exits frequency modulation and enters the speed recovery stage, the frequency response characteristics of the secondary frequency drop system under unbalanced power are established to obtain the maximum frequency deviation of the secondary drop; The maximum frequency deviation of the primary and secondary drops, the maximum frequency change rate and the charge state of the energy storage are used to obtain the energy storage frequency regulation control parameters according to the fuzzy control strategy to achieve wind and storage joint frequency regulation control; the energy storage device adaptively adjusts the frequency regulation control parameters according to the frequency operation state of the power system to reduce the depth of the secondary frequency drop and the probability of its occurrence; The method of obtaining the energy storage frequency modulation control parameters according to the fuzzy control strategy specifically includes: using the energy storage's own charge state, frequency deviation and frequency change rate as the input of the fuzzy controller, using the virtual inertia and droop coefficient of the energy storage participating in the frequency modulation as the output of the fuzzy controller, designing the domain and membership function of the fuzzy controller's input and output variables, establishing a fuzzy rule table, and obtaining the energy storage frequency modulation control parameters according to the fuzzy rule table; The basic domain of frequency deviation is [-1Hz, 1Hz], and the corresponding fuzzy subset is {NB, NS, ZO, PS, PB}; the basic domain of frequency deviation rate is [-0.4Hz, 0.4Hz], and the corresponding fuzzy subset is {NB, NS, ZO, PS, PB}; the basic domain of energy storage's own state of charge is [0.15, 0.95], and the corresponding fuzzy subset is {VS, S, RS, M, RB, B, VB}; the basic domain of energy storage frequency control parameters is [0, 5], and the corresponding fuzzy subset is {NB, S, NS, ZO, PS, B, PB}; the fuzzy rule table is established with the above domains, as shown in Table 1 below: Table 1 Among them, SOC is the state of charge of the energy storage itself, Δf is the frequency deviation, and df / dt is the frequency change rate; When the energy storage battery's own charge state is used as the input of the fuzzy controller, the energy storage battery's own charge state is set as a normal value in the range of 0.15 to 0.95, and a value below 0.15 or above 0.95 is set as an abnormal operating state of the energy storage battery.

2. The wind power storage combined frequency regulation control method taking into account the secondary drop of the power system frequency according to claim 1 is characterized in that: The frequency response characteristic expression of the system is: f(t)=Me αt cos(ωt+θ)+C Where t is time, T J is the inertia time constant of the conventional synchronous unit, T G K is the time constant of the speed regulator action. W1 is the droop coefficient, K W2 is the virtual inertia coefficient, K G The unit power adjustment is ΔP L is the disturbance load.

3. The wind power storage combined frequency regulation control method taking into account the secondary drop of the power system frequency according to claim 2 is characterized in that: The inertia time constant T of the conventional synchronous unit J The following conventional synchronous unit rotor motion equation is satisfied: in, is the frequency change rate, P G0 is the initial output of the conventional synchronous unit, ΔP G The additional power generated by the conventional synchronous unit, P w0 is the initial output of the wind turbine, ΔP w is the additional power generated by the wind turbine, P L0 The original load of the system.

4. The wind power storage combined frequency regulation control method taking into account the secondary drop of the power system frequency according to claim 2 is characterized in that: The time constant T of the speed regulator action G Satisfies the following expression: Among them, ΔP G is the additional power generated by the conventional synchronous unit, and Δf is the frequency deviation.

5. The wind power storage combined frequency regulation control method taking into account the secondary drop of the power system frequency according to claim 2 is characterized in that: The expression of the maximum frequency change rate is:

6. The wind power storage combined frequency regulation control method taking into account the secondary drop of the power system frequency according to claim 2 is characterized in that: The expression of the maximum frequency deviation of a drop is: in, 7. The wind power storage combined frequency regulation control method taking into account the secondary drop of the power system frequency according to claim 2 is characterized in that: The expression of the maximum frequency deviation of the secondary drop is: Among them, f off is the moment when the fan exits frequency regulation, ΣΔP d is the total unbalanced power of the system.

8. The wind power storage combined frequency regulation control method taking into account the secondary drop of the power system frequency according to claim 7 is characterized in that: The total unbalanced power of the system is: in, is the fan response power, is the mechanical power of the fan.

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