Low-inertia power system minimum frequency assessment method and apparatus

Abstract

The application belongs to the technical field of electric power, and provides a minimum frequency evaluation method and device for a low-inertia power system, which comprises the following steps: establishing a frequency closed-loop response model of the power system; adding different frequency disturbances to each generator in the power system in a fast frequency response stage of the frequency closed-loop response model to obtain the response power of each generator under different frequency disturbances; performing polynomial fitting on the response power of each generator under different frequency disturbances, and determining the frequency response transfer function of each generator according to the fitting result; determining the overall frequency response transfer function of the frequency closed-loop response model according to the frequency response transfer functions of the generators, and determining the minimum frequency of the power system based on the overall frequency response transfer function. The application can solve the problem that it is difficult to determine the minimum frequency of a low-inertia power system in the prior art.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electric power, and particularly relates to a minimum frequency evaluation method and device for a low-inertia power system. BACKGROUND

[0002] Low inertia has increasingly become a key problem of high-proportion new energy power systems. With the increase of a large amount of renewable energy, the characteristics of the power system have been changed. Energy storage devices with power electronic interfaces such as battery energy storage, super capacitor energy storage and flywheel energy storage have the advantages of fast response speed, strong climbing ability, flexible power output and strong plasticity. Using fast-response energy storage for primary frequency modulation is an effective measure to ensure the frequency safety of the power grid in the new form.

[0003] However, the increase of renewable energy has affected the frequency stability of the power system in many aspects. Simply put, the decrease of the inertia of the power system is considered to be replaced by the inverter-based renewable energy. Many other parameters will affect the frequency stability of the power system. The main parameters affecting the minimum frequency include the proportion of new energy power generation, the inertia time constant of the system, the frequency modulation capability, the disturbance size and the like. In addition, the development of inverter-based facilities has led to the emergence of fast frequency response, which is much faster than the current primary frequency response, and the frequency recovery characteristics can be greatly affected by the control scheme. The current research on energy storage control strategy, whether the energy storage participates in frequency modulation alone or cooperates with wind farms and DC field stations for frequency modulation, is basically based on comprehensive inertia control strategy. Due to the complexity of the swing equation and the control strategy, it is difficult to use the Laplace frequency domain algebraic equation to solve the minimum frequency of the system. SUMMARY

[0004] Therefore, the embodiment of the present application provides a minimum frequency evaluation method and device for a low-inertia power system to solve the problem that it is difficult to determine the minimum frequency of the low-inertia power system in the prior art.

[0005] The first aspect of the embodiment of the present application provides a minimum frequency evaluation method for a low-inertia power system, which comprises:

[0006] establishing a frequency closed-loop response model of the power system;

[0007] in the fast frequency response stage of the frequency closed-loop response model, adding different frequency disturbances to each generator in the power system to obtain the response power of each generator under different frequency disturbances;

[0008] performing polynomial fitting on the response power of each generator under different frequency disturbances, and determining the frequency response transfer function of each generator according to the fitting result;

[0009] The overall frequency response transfer function of the frequency closed-loop response model is determined according to the frequency response transfer function of each generator, and the minimum frequency of the power system is determined based on the overall frequency response transfer function.

[0010] In conjunction with the first aspect, in a possible implementation of the first aspect, adding a different frequency disturbance to each generator in the power system includes:

[0011] A different step disturbance is added to each generator in the power system;

[0012] Alternatively, a different ramp disturbance is added to each generator in the power system.

[0013] Furthermore, before performing polynomial fitting on the output power of each generator, the order of the polynomial is determined. Determining the order of the polynomial includes:

[0014] If the added frequency disturbance is a step disturbance s , then the polynomial contains at least one 1 / s item;

[0015] If the added frequency disturbance is a ramp disturbance s 2 , then the polynomial contains at least one s item;

[0016] in, s represents the complex frequency domain.

[0017] In conjunction with the first aspect, in a possible implementation of the first aspect, the frequency response transfer function of each generator is expressed as:

[0018] ;

[0019] Where, 、 、 are the coefficients obtained by fitting, s represents the complex frequency domain.

[0020] Furthermore, the overall frequency response transfer function of the frequency closed-loop response model is determined based on the frequency response transfer function of each generator, including:

[0021] Obtain the normalized value of the rated capacity of each generator;

[0022] according to Determine the overall frequency response transfer function of the frequency closed-loop response model; where, l is the number of generators in the power system, is the normalized value of the generator's rated capacity.

[0023] Further, the lowest frequency of the power system is determined based on the overall frequency response transfer function, comprising:

[0024] The frequency response function of the power system is determined based on the overall frequency response transfer function.

[0025] The frequency response function is calculated to obtain the lowest frequency of the power system.

[0026] Further, the frequency response function of the power system is represented as:

[0027]

[0028] In the formula, is the response frequency of the power system, is the frequency disturbance, is the equivalent inertia of the power system, is the overall frequency response transfer function, s represents the complex frequency domain.

[0029] The second aspect of the embodiment of the present application provides a lowest frequency evaluation device of a low-inertia power system, which comprises:

[0030] The disturbance module is configured to establish a frequency closed-loop response model of the power system, and to add different frequency disturbances to each generator in the power system to obtain the response power of each generator under different frequency disturbances in a fast frequency response stage of the frequency closed-loop response model.

[0031] The fitting module is configured to perform polynomial fitting on the response power of each generator under different frequency disturbances, and to determine the frequency response transfer function of each generator according to the fitting result.

[0032] The calculation module is configured to determine the overall frequency response transfer function of the frequency closed-loop response model according to the frequency response transfer functions of the generators, and to determine the lowest frequency of the power system based on the overall frequency response transfer function.

[0033] The third aspect of the embodiment of the present application provides an electronic device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the lowest frequency evaluation method of the low-inertia power system according to the first aspect when executing the computer program.

[0034] The fourth aspect of the embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executable on the processor to implement the steps of the lowest frequency evaluation method of the low-inertia power system according to the first aspect.

[0035] ​Compared with the prior art, the embodiment of the present application has the beneficial effects that:

[0036] The embodiment of the present application can accurately calculate the lowest frequency of the power system, and based on the obtained frequency response curve, the influence of the inertia time constant of the power system and the proportion of the fast frequency response generator set on the lowest frequency can be effectively analyzed, and the application of the present application in the new power system resource planning evaluation can effectively ensure the frequency stability of the power system. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0038] Figure 1 is the implementation flowchart of the lowest frequency evaluation method of the low-inertia power system provided by the embodiment of the present application;

[0039] Figure 2 is the schematic diagram of the frequency closed-loop response model provided by the embodiment of the present application;

[0040] Figure 3 is the structural schematic diagram of the lowest frequency evaluation device of the low-inertia power system provided by the embodiment of the present application;

[0041] Figure 4 is the structural schematic diagram of the electronic device provided by the embodiment of the present application. DETAILED DESCRIPTION

[0042] In the following description, specific details are set forth in order to provide a thorough understanding of the embodiments of the present application, such as specific system structures, techniques, etc. However, it should be apparent to those skilled in the art that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted in order not to obscure the description of the present application with unnecessary details.

[0043] In order to illustrate the technical solutions of the present application, the following will be described through specific embodiments.

[0044] Figure 1 This is a schematic diagram of the implementation flow of the method for evaluating the minimum frequency of a low-inertia power system provided by an embodiment of the present invention. Figure 1 As shown, the method includes:

[0045] Step S101: establishing a frequency closed-loop response model of the power system.

[0046] In this embodiment, based on the second-order frequency response model of the power system, a frequency closed-loop response model is established under the condition of large target power disturbance variation, which accurately reflects the key features including the minimum frequency value and frequency recovery characteristics. Figure 2 As shown in the figure, is the overall frequency response transfer function, is the system inertia function determined by the system swing equation, P e ( s ) is the response power, P D ( s ) is the frequency disturbance in the fast frequency response stage, is the response frequency, P m ( s ) is the speed regulator response and is ignored as 0. In this frequency closed-loop response model, what needs to be calculated is the overall frequency response transfer function ,Know After that, the frequency response function of the frequency closed-loop response model can be obtained, and then the lowest frequency can be obtained.

[0047] Step S102 : In the fast frequency response stage of the frequency closed-loop response model, different frequency disturbances are added to each generator in the power system to obtain the response power of each generator under different frequency disturbances.

[0048] As a possible implementation manner, different frequency disturbances are added to each generator in the power system, including adding different step disturbances to each generator in the power system.

[0049] In this embodiment, different frequency disturbances are added to each generator in the power system, including:

[0050] A different step disturbance is added to each generator in the power system;

[0051] Alternatively, a different ramp disturbance is added to each generator in the power system.

[0052] Adding a step disturbance , the step response of each generator is:

[0053] .

[0054] Adding ramp disturbance The ramp response of each generator is:

[0055] .

[0056] Thus, the response power of each generator under different frequency disturbances can be calculated.

[0057] In step S103, polynomial fitting is performed on the response power of each generator under different frequency disturbances, and the frequency response transfer function of each generator is determined according to the fitting result.

[0058] In this embodiment, the polynomial fitting can be performed on a series of response powers of each generator in a curve fitting manner, and the frequency response transfer function of each generator is obtained. .

[0059] Specifically, .

[0060] By comparing the error between the real frequency response curve under the frequency disturbance and the curve obtained by fitting, the values of the coefficients of the polynomial can be determined , , , and the frequency response transfer function of the frequency closed-loop response model is obtained. .

[0061] In the formula, a, b, c, d, e, f, g, h, i, j, k, and l are the coefficients obtained by fitting, , , , and s represents the complex frequency domain. s

[0062] In step S104, the overall frequency response transfer function of the frequency closed-loop response model is determined according to the frequency response transfer functions of the generators, and the minimum frequency of the power system is determined based on the overall frequency response transfer function.

[0063] In this embodiment, according to the frequency response transfer functions of the generators , the total frequency response transfer function of the power system , that is, the overall frequency response transfer function of the frequency closed-loop response model, is obtained, and the frequency response function of the power system is determined, and the minimum frequency of the power system is obtained.

[0064] ​It can be seen that the embodiment of the present application can establish a frequency closed-loop response model of the power system, and in the fast frequency response stage of the frequency closed-loop response model, different frequency disturbances are added to each generator in the power system, the frequency response transfer function of each generator is determined through polynomial fitting, the overall frequency response transfer function of the frequency closed-loop response model is obtained, and the minimum frequency of the power system is further determined. The present application can accurately calculate the minimum frequency of the power system, and based on the obtained frequency response curve, the fast frequency response generator set proportion limit value of the power system can be effectively analyzed, the influence of the inertia time constant of the power system and the fast frequency response generator set proportion on the minimum frequency can be determined, and the present application is applied to the new power system resource planning evaluation, and the frequency stability of the power system can be effectively ensured.

[0065] As a possible implementation manner, before the output power of each generator is polynomial fitted, the order of the polynomial is determined.

[0066] The order of the polynomial includes:

[0067] If the added frequency disturbance is a step disturbance s , then the polynomial at least contains one 1 / s term;

[0068] If the added frequency disturbance is a ramp disturbance s 2 , then the polynomial at least contains one s term;

[0069] Wherein, s represents the complex frequency domain.

[0070] In the embodiment, when the power system is subjected to a step disturbance, that is, the input disturbance P D ( s )= s , to avoid frequency response divergence, at least one 1 / s term is needed. When the power system is subjected to a ramp disturbance, that is, the input disturbance P D ( s )= s 2 , to avoid frequency response divergence, at least one s term is needed.

[0071] As a possible implementation manner, the overall frequency response transfer function of the frequency closed-loop response model is determined according to the frequency response transfer function of each generator, including:

[0072] obtaining a normalized value of rated capacity of each generator;

[0073] According to determining an overall frequency response transfer function of the frequency closed loop response model, wherein, l is the number of generators in the power system, is the normalized value of rated capacity of the generator.

[0074] In the embodiment, may be further expressed as H (1,1, s ):

[0075]

[0076] When the fitting function does not converge, the fitting function can also be used as an initial order, and the order is increased and the subsequent steps are repeated until the fitting function converges.

[0077] As a possible implementation, determining the minimum frequency of the power system based on the overall frequency response transfer function comprises:

[0078] determining a frequency response function of the power system based on the overall frequency response transfer function;

[0079] calculating the frequency minimum value of the frequency response function to obtain the minimum frequency of the power system.

[0080] In the embodiment, the single-area load frequency control in which the fast frequency response generator group is dominant in frequency control and the frequency response is controlled before the governor operates, so the response of the governor can be ignored P m ( s ), and further, due to small system damping, the following formula can be obtained:

[0081]

[0082] In the formula, is the frequency response, P D ( s ) is the frequency disturbance, G ( s ) is a system inertia function determined by a system swing equation, is a response function corresponding to the fast frequency response generator group.

[0083] Further, the following is obtained:

[0084]

[0085] H sysThe equivalent inertia of the system can be calculated by the following formula:

[0086]

[0087] Further, by substituting the polynomial coefficients obtained in the previous step, we get:

[0088]

[0089] The frequency response function is calculated The minimum frequency of the power system can be obtained by calculating the minimum value of the frequency.

[0090] In combination with the above, the present application proposes a closed-loop frequency response prediction model to analyze the minimum frequency for a low-inertia power system with a high proportion of new energy. Based on the second-order frequency response model, the closed-loop feedback frequency response curve, including the minimum frequency and the frequency recovery characteristics, can be accurately reflected under disturbance. At the same time, an analytical solution of the minimum frequency can be obtained. This method can effectively analyze the limit of the proportion of fast frequency response generating units in the new power system constrained by the frequency key feature index. It can also be used to analyze the impact of the inertia time constant and the proportion of fast frequency response generating units on the minimum frequency. It can be applied to the resource planning evaluation of the new power system to effectively ensure the frequency stability.

[0091] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution. The execution order of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0092] The embodiment of the present application provides a minimum frequency evaluation device for a low-inertia power system, as shown in Figure 3 The minimum frequency evaluation device 30 for the low-inertia power system comprises:

[0093] The disturbance module 31 is used to establish a frequency closed-loop response model of the power system, and in the fast frequency response stage of the frequency closed-loop response model, different frequency disturbances are added to each generator in the power system to obtain the response power of each generator under different frequency disturbances.

[0094] The fitting module 32 is used to perform polynomial fitting on the response power of each generator under different frequency disturbances, and determine the frequency response transfer function of each generator according to the fitting result.

[0095] The calculation module 33 is used to determine the overall frequency response transfer function of the frequency closed-loop response model according to the frequency response transfer function of each generator, and determine the minimum frequency of the power system based on the overall frequency response transfer function.

[0096] As a possible implementation, the perturbation module 31 is specifically configured to:

[0097] a different step perturbation is added to each generator in the power system;

[0098] or, a different ramp perturbation is added to each generator in the power system.

[0099] As a possible implementation, before the polynomial fitting of the output power of each generator, the fitting module 32 is further configured to determine the order of the polynomial.

[0100] The determination of the order of the polynomial includes:

[0101] if the added frequency perturbation is a step perturbation s , the polynomial contains at least one 1 / s term;

[0102] if the added frequency perturbation is a ramp perturbation s 2 , the polynomial contains at least one s term;

[0103] wherein, s represents the complex frequency domain.

[0104] As a possible implementation, the frequency response transfer function of each generator is expressed as:

[0105] ;

[0106] wherein, , , are the fitting coefficients, s represents the complex frequency domain.

[0107] As a possible implementation, the calculation module 33 is specifically configured to:

[0108] obtain the normalized value of the rated capacity of each generator;

[0109] determine the overall frequency response transfer function of the frequency closed-loop response model according to ; wherein, l is the number of generators in the power system, is the normalized value of the rated capacity of the generator.

[0110] As a possible implementation, the calculation module 33 is specifically configured to:

[0111] determine the frequency response function of the power system based on the overall frequency response transfer function;

[0112] Calculate the minimum frequency value of the frequency response function to obtain the minimum frequency of the power system.

[0113] As a possible implementation method, the frequency response function of the power system is expressed as:

[0114] ;

[0115] Where, is the response frequency of the power system, is the frequency disturbance, is the equivalent inertia of the power system, is the overall frequency response transfer function, s represents the complex frequency domain.

[0116] Figure 4 FIG is a schematic diagram of an electronic device 40 provided by an embodiment of the present invention. Figure 4 As shown, the electronic device 40 of this embodiment includes: a processor 41, a memory 42, and a computer program 43 stored in the memory 42 and executable on the processor 41, such as a minimum frequency evaluation program for a low-inertia power system. When the processor 41 executes the computer program 43, the steps in the above-mentioned embodiments of the method for evaluating the minimum frequency of a low-inertia power system are implemented, such as Figure 1 Alternatively, when the processor 41 executes the computer program 43, the functions of the modules in the above-mentioned device embodiments are realized, for example Figure 3 The functions of modules 31 to 33 are shown.

[0117] Exemplarily, the computer program 43 may be divided into one or more modules / units, one or more of which are stored in the memory 42 and executed by the processor 41 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program 43 in the electronic device 40.

[0118] The electronic device 40 may be a computing device such as a desktop computer, a notebook computer, a PDA, or a cloud server. The electronic device 40 may include, but is not limited to, a processor 41 and a memory 42. Those skilled in the art will understand that Figure 4 It is only an example of the electronic device 40 and does not constitute a limitation of the electronic device 40. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device 40 may also include input and output devices, network access devices, buses, etc.

[0119] The processor 41 can be a central processing unit (CPU), and can also be other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0120] The memory 42 can be an internal storage unit of the electronic device 40, such as a hard disk or a memory of the electronic device 40. The memory 42 can also be an external storage device of the electronic device 40, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 40. Further, the memory 42 can include both the internal storage unit and the external storage device of the electronic device 40. The memory 42 is used to store computer programs and other programs and data required by the electronic device 40. The memory 42 can also be used to temporarily store data that has been output or will be output.

[0121] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit, and the integrated unit can be realized in the form of hardware or in the form of software. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the above system can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0122] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0123] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0124] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / equipment and method can be implemented in other ways. For example, the apparatus / equipment embodiments described above are merely schematic. The division of the modules or units is merely a logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed coupling or direct coupling or communication connection between the units can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or in other forms.

[0125] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. they can be located in one place, or distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0126] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0127] The integrated modules / units, if implemented in the form of software functional units and sold or used as independent products, can be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned various method embodiments can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms, etc. The computer readable medium can include any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0128] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method for minimum frequency assessment of a low-inertia power system, characterized by, The method comprises the following steps: establishing a frequency closed-loop response model of the power system; adding different frequency disturbances to each generator in the power system in a fast frequency response stage of the frequency closed-loop response model to obtain the response power of each generator under different frequency disturbances; performing polynomial fitting on the response power of each generator under different frequency disturbances to determine the frequency response transfer function of each generator according to the fitting result; determining the overall frequency response transfer function of the frequency closed-loop response model according to the frequency response transfer function of each generator; determining the frequency response function of the power system based on the overall frequency response transfer function; calculating the frequency minimum value of the frequency response function to obtain the minimum frequency of the power system.

2. The method of claim 1, wherein the minimum frequency of the low-inertia power system is determined based on a minimum frequency of a power grid connected to the low-inertia power system. The method of adding different frequency disturbances to each generator in the power system comprises the following steps: adding different step disturbances to each generator in the power system; or, adding different ramp disturbances to each generator in the power system.

3. The method of claim 2, wherein the minimum frequency of the low-inertia power system is determined based on a minimum frequency of a power grid connected to the low-inertia power system. Before performing polynomial fitting on the response power of each generator, the method further comprises the step of determining the order of the polynomial. The step of determining the order of the polynomial comprises the following steps: If the frequency perturbation added is a step perturbation s then the polynomial contains at least one term with 1 s ; If the frequency perturbation added is a ramp perturbation s 2 then the polynomial contains at least one s term; wherein s represents the complex frequency domain.

4. The method of claim 1, wherein the minimum frequency of the low-inertia power system is determined based on a minimum frequency of a power grid connected to the low-inertia power system. The frequency response transfer function of each generator is expressed as: ； wherein , , are the polynomial coefficients obtained from the fit, s denotes the complex frequency domain.

5. The method of claim 4, wherein the minimum frequency of the low-inertia power system is determined based on a minimum frequency of a power grid connected to the low-inertia power system. The method of determining the overall frequency response transfer function of the frequency closed-loop response model according to the frequency response transfer function of each generator comprises the following steps: obtaining the normalized value of the rated capacity of each generator; According to determining an overall frequency response transfer function of the frequency closed loop response model; where, l is the number of generators in the power system, is the normalized value of the rated capacity of the generator.

6. The method of claim 1, wherein the minimum frequency of the low-inertia power system is determined based on a minimum frequency of a power grid connected to the low-inertia power system. The frequency response function of the power system is expressed as: ； wherein is the response frequency of the power system, is the frequency disturbance, is the equivalent inertia of the power system, is the overall frequency response transfer function, s denotes the complex frequency domain.

7. A minimum frequency evaluation device for a low-inertia power system, characterized by, The method comprises the following steps: a disturbance module, configured to establish a frequency closed-loop response model of the power system, and to add different frequency disturbances to each generator in the power system in a fast frequency response stage of the frequency closed-loop response model to obtain the response power of each generator under different frequency disturbances; a fitting module, configured to perform polynomial fitting on the response power of each generator under different frequency disturbances to determine the frequency response transfer function of each generator according to the fitting result; a calculation module, configured to determine the overall frequency response transfer function of the frequency closed-loop response model according to the frequency response transfer function of each generator, to determine the frequency response function of the power system based on the overall frequency response transfer function, and to calculate the frequency minimum value of the frequency response function to obtain the minimum frequency of the power system.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The computer program is executed by the processor to implement the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 8. The computer program is executed by the processor to implement the steps of the method according to any one of claims 1 to 6.

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