Method for analyzing cross-scale interaction of power system under transient disturbance

Abstract

The invention discloses a method for analyzing cross-scale interaction of an electric power system under transient disturbance, which belongs to the technical field of electric power system control and comprises the following steps of: performing second-order Taylor expansion on a nonlinear differential equation of an x-domain state variable of the electric power system under transient disturbance at an unbalanced point; sequentially transforming the nonlinear differential equation of the x-domain state variable into a y-domain, a z-domain and an m-domain to obtain an analytical expression of an m-domain state variable; compared with the first-order Taylor expansion, the second-order Taylor expansion comprises a second-order nonlinear term matrix, so that the strong nonlinear dynamic behavior of the power system can be described more accurately. Further, the analytical expression of the m-domain state variable is inversely transformed into a z-domain, a y-domain and an x-domain in sequence to obtain an analytical expression of an x-domain state variable of the power system under transient disturbance, and the analytical expression of the x-domain state variable comprises a constant term, an independent frequency term and a coupling frequency term; it describes multi-time scale features of the power system at non-equilibrium points.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system control, and more specifically, relates to an analysis method for cross-scale interaction of a power system under transient disturbance. Background Art

[0002] In recent years, the penetration rate of new energy sources has continued to increase, and the problem of broadband oscillation with unknown mechanisms has led to large-scale trawling of new energy units. In the new power system with power electronics, the physical and control structure of power electronic equipment is very different from that of traditional synchronous units. The composition structure and operation form of the power system have undergone tremendous changes, and the transient dynamic behavior of the system under disturbance has undergone profound changes. The basic feature that distinguishes power electronic equipment from electromagnetic equipment is multi-scale control. Understanding the dynamic characteristics of equipment under multi-scale control is a study of the stability problem of power electronic power systems.

[0003] At present, modal analysis is mainly used for the stability of power system under small disturbances. However, in the system with a high proportion of new energy, the system exhibits strong nonlinear characteristics. Under the same disturbance, the power system is at a non-equilibrium point during the transient process.

[0004] That is, the modal analysis method based on the first-order Taylor expansion cannot perform cross-scale interaction analysis on the non-equilibrium points of the power system under transient disturbances. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides an analysis method for cross-scale interactions of power systems under transient disturbances, which aims to solve the technical problem that the modal analysis method based on first-order Taylor expansion cannot perform cross-scale interaction analysis of power systems under transient disturbances.

[0006] To achieve the above object, according to one aspect of the present invention, a method for analyzing cross-scale interaction of power systems under transient disturbances is provided, comprising:

[0007] S1: construct a nonlinear differential equation of the x-domain state variable with physical meaning for the power system under transient disturbance, perform a second-order Taylor expansion on the differential equation of the x-domain state variable at a non-equilibrium point, and then perform a linear coordinate transformation to obtain a differential equation of the y-domain state variable containing a second-order nonlinear term; perform a normal form nonlinear transformation on the differential equation of the y-domain state variable to eliminate the nonlinear term and convert it into a differential equation of the z-domain state variable;

[0008] S2: transferring the differential equation of the z-domain state variable to the decoupled domain m to obtain an analytical expression of the m-domain state variable;

[0009] S3: Inversely transforming the analytical expression of the m-domain state variable into the z-domain, y-domain and x-domain in sequence, so as to convert the m-domain that does not contain actual physical meaning into the x-domain with actual physical meaning, and obtain the analytical expression of the x-domain state variable of the power system under transient disturbance, wherein the analytical expression of the x-domain state variable is expanded to include a constant term, an independent frequency term and a coupled frequency term;

[0010] S4: Analyze the independent frequency terms and the coupled frequency terms to determine the cross-scale characteristics of the power system under transient disturbances.

[0011] In one embodiment, the S1 includes:

[0012] Construct the power system model under transient disturbance Differential equations of x-domain state variables with Taylor second-order expansion at nonequilibrium points

[0013] Substituting x=Uy into get

[0014] Let y = z + G(z), and take the derivative of y = z + G(z) to get Bring it in get

[0015] Set (I+DG(z)) -1 =I-DG(z) into Obtain z=P-DG(z)P+Λz+ΛG(z)+F(z)-(DG(z))Λz+O(3);

[0016] Where P = U -1 B, O(3) is the third-order and higher-order terms, D is the Jacobian matrix operator, U is the right eigenvector matrix of x, H j is the Hessian matrix of the jth state variable, Λ is the characteristic root of matrix A λ 1 ,λ 2 , ···, λ n The diagonal matrix formed by

[0017] Let F(z)=(DG(z))Λz-ΛG(z) and calculate and the differential equations for the z-domain state variables It is the coefficient matrix of z after merging -DG(z)P+Λz.

[0018] In one embodiment, S2 includes: converting the differential equation of the state variable in the z domain into the m domain by transforming z=Rm to obtain the differential equation of the state variable in the m domain: R is The right eigenvector matrix composed of the right eigenvector and the generalized right eigenvector; The integration is performed to obtain the analytical expression of the m-domain state variables.

[0019] In one embodiment, in S3: when the matrix When there is no repeated root, The jth analytical expression of the x-domain state variable of the power system under transient disturbance is Among them, the j-th state variable x j Contains the constant term C j0 , independent frequency terms and the coupling frequency term η 1 , η 2 …η n yes Characteristic root.

[0020] In one embodiment, in S3:

[0021] For the matrix The i-th heavy characteristic root η si The multiplicity is e si , then the corresponding analytical solution is:

[0022]

[0023] For the matrix Non-repeated characteristic roots, the corresponding analytical solution is:

[0024] When the matrix When there are i repeated roots, the jth analytical expression of the x-domain state variable of the power system under transient disturbance is: Among them, the j-th state variable x j Contains the constant term C ji0 , independent frequency terms and the coupling frequency term yes Characteristic root, dmax is the maximum multiplicity of all repeated roots.

[0025] In one embodiment, the S4 includes:

[0026] The characteristic roots in the independent frequency terms and the characteristic roots corresponding to the coupled frequency terms are analyzed to obtain cross-scale characteristics of the power system under transient disturbances.

[0027] According to another aspect of the present invention, there is provided an analysis device for cross-scale interaction of power system under transient disturbance, comprising:

[0028] A construction module is used to construct a Taylor-expanded differential equation of an x-domain state variable of an electric power system under transient disturbances, perform a linear coordinate transformation on the differential equation of the x-domain state variable to obtain a differential equation of a y-domain state variable containing a second-order nonlinear term; perform a normal form nonlinear transformation on the differential equation of the y-domain state variable to eliminate the nonlinear term and convert it into a differential equation of a z-domain state variable;

[0029] A decoupling module, used for transferring the differential equation of the z-domain state variable to the domain m of the first-order decoupling to obtain an analytical expression of the m-domain state variable;

[0030] A transformation module, used for inversely transforming the analytical expression of the m-domain state variable into the z-domain, y-domain and x-domain in sequence, so as to convert the m-domain that does not contain actual physical meaning into the x-domain with actual physical meaning, and obtain the analytical expression of the x-domain state variable of the power system under transient disturbance, wherein the analytical expression of the x-domain state variable is expanded to include a constant term, an independent frequency term and a coupled frequency term;

[0031] An analysis module is used to analyze the independent frequency terms and the coupled frequency terms to determine the cross-scale characteristics of the power system under transient disturbances.

[0032] According to another aspect of the present invention, there is provided a control system for an electric power system, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0033] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0034] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0035] (1) Compared with the traditional normal form method which can only be applied to the equilibrium point, the present invention provides an analysis method for the cross-scale interaction of the power system under transient disturbance, and performs a second-order Taylor expansion on the nonlinear differential equation of the x-domain state variable with physical meaning of the power system under transient disturbance at the non-equilibrium point, so as to transform the nonlinear differential equation of the x-domain state variable into the y-domain, z-domain and m-domain in turn to obtain the analytical expression of the m-domain state variable; the second-order Taylor expansion is relative to the first-order Taylor expansion, and the second-order Taylor expansion of the system contains the Jacobian matrix of the first-order Taylor expansion and the second-order nonlinear term matrix, so it can more accurately characterize the strong nonlinear dynamic behavior of the power system. Further, the analytical expression of the m-domain state variable is successively transformed into the z-domain, y-domain and x-domain, so as to transform the m-domain without actual physical meaning into the x-domain with actual physical meaning, and obtain the analytical expression of the x-domain state variable of the power system under transient disturbance. Since the analytical expression of the x-domain state variable includes constant terms, independent frequency terms and coupled frequency terms, it describes the multi-time scale characteristics of the power system at the non-equilibrium point. That is, this application overcomes the problem that the normal form of non-equilibrium points is no longer applicable, and extends the normal form method to high-order nonlinear power systems, providing strong support for the stability analysis of the system after disturbances. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flow chart of a method for analyzing cross-scale interaction of a power system under transient disturbance provided in Example 1 of the present invention;

[0037] Figure 2 It is a schematic diagram of a flow chart of sequentially transforming a nonlinear differential equation of a state variable in the x domain to the y domain, the z domain, and the m domain, provided by Embodiment 1 of the present invention;

[0038] Figure 3 It is a flowchart of sequentially inversely transforming the nonlinear differential equation of the m-domain state variable into the z-domain, y-domain and x-domain provided by Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] Example 1

[0041] like Figure 1 As shown, this embodiment provides an analysis method for cross-scale interaction of power system under transient disturbance, including: S1-S4.

[0042] S1: Construct a nonlinear differential equation of the x-domain state variables with physical meaning for the power system under transient disturbances, perform Taylor expansion on the differential equation of the x-domain state variables at non-equilibrium points, and then perform linear coordinate transformation to obtain the differential equation of the y-domain state variables containing second-order nonlinear terms; perform a normal form nonlinear transformation on the differential equation of the y-domain state variables to eliminate the nonlinear terms and convert it into a differential equation of the z-domain state variables.

[0043] S2: Transfer the differential equations of the z-domain state variables to the decoupled domain m to obtain the analytical expressions of the m-domain state variables.

[0044] S3: The analytical expressions of the m-domain state variables are transformed back to the z-domain, y-domain and x-domain in turn, so as to convert the m-domain that does not contain actual physical meaning into the x-domain with actual physical meaning, and obtain the analytical expressions of the x-domain state variables of the power system under transient disturbances. The analytical expressions of the x-domain state variables are expanded to include constant terms, independent frequency terms and coupled frequency terms.

[0045] S4: Analyze independent frequency terms and coupled frequency terms to determine the cross-scale characteristics of the power system under transient disturbances.

[0046] In one embodiment, S1 includes: constructing a power system model under transient disturbance Differential equations of x-domain state variables with Taylor second-order expansion at nonequilibrium points Substituting x=Uy into get Let y = z + G(z), and take the derivative of y = z + G(z) to get Bring it in get Furthermore, we set (I+DG(z)) -1 =I-DG(z) into get P=U -1 B, O(3) is the third-order and higher-order terms, D is the Jacobian matrix operator, U is the right eigenvector matrix of x, H j is the Hessian matrix of the jth state variable, Λ is the characteristic root of matrix A λ 1 ,λ 2 ,···,λ n The diagonal matrix is ​​formed; let F(z)=(DG(z))Λz-ΛG(z) to calculate and the differential equations for the z-domain state variables is the coefficient matrix of z after the combination of -DG(z)P+Λz. Further, S2 includes: converting the differential equation of the state variable in the z domain to the m domain by transforming z=Rm, and obtaining the differential equation of the state variable in the m domain: R is The right eigenvector matrix composed of the right eigenvector and the generalized right eigenvector; The integration is performed to obtain the analytical expression of the m-domain state variables.

[0047] Among them, the traditional normal form method analyzes at the equilibrium point, at this time P = 0, and the decoupled differential equation can be obtained, but the present invention analyzes at the non-equilibrium point, so P ≠ 0, and the following equation needs to be solved: Therefore, the z domain is converted to the m domain by transforming z = Rm, and the state variables in the m domain are decoupled: Where Q = R -1 P, for There are two situations, with and without repeated roots, which are discussed below.

[0048] Figure 2 The flowchart of converting the state variable x to the m domain is shown. First, after the linear coordinate transformation, the y domain with first-order decoupling is obtained, but the y domain still contains second-order nonlinear terms. Then, the nonlinear terms are eliminated through the normal form nonlinear transformation and converted to the z domain. However, the analytical solution cannot be directly obtained in the z domain at the non-equilibrium point at this time, so the z domain is converted to the m domain with first-order decoupling, and then the m domain analytical expression is obtained.

[0049] Figure 3 The flowchart of converting the state variable from the m-domain to the x-domain is shown. After obtaining the analytical expression in the m-domain, the m-domain without actual physical meaning is converted to the x-domain with actual physical meaning through a series of inverse transformations. The time domain solution of the state variable in the x-domain is analyzed to discover the multi-time scale characteristics and cross-scale phenomena of the system.

[0050] In one embodiment, in S3: when the matrix When there is no repeated root, The jth analytical expression of the x-domain state variable of the power system under transient disturbance Among them, the j-th state variable x j Contains the constant term C j0 , independent frequency terms and the coupling frequency term η 1 ,η 2 …η n yes Characteristic root.

[0051] The jth state variable x j It contains constant term, independent frequency term and coupled frequency term. The coefficients before each term are C j0 , C ji , C jklThe constant term is caused by the non-zero derivatives of the state variables at the non-equilibrium point. In the normal form analysis method considering the second-order Taylor expansion at the non-equilibrium point, the coupled frequency term will show cross-scale phenomena, so the dynamic process of the system (i.e., non-equilibrium point) contains cross-scale characteristics. In addition, because the z-domain equation contains the Jacobian matrix DG of the normal form nonlinear transformation 2 (z), so the frequency of the independent frequency terms of the second-order expansion at the non-equilibrium point is different from the frequency of the first-order Taylor expansion.

[0052] In one embodiment, in S3: for the matrix The i-th heavy characteristic root η si The multiplicity is e si , then the corresponding analytical solution is:

[0053]

[0054] For the matrix Non-repeated characteristic roots, the corresponding analytical solution is:

[0055] When the matrix When there are i kinds of repeated roots, the jth analytical expression of the x-domain state variable of the power system under transient disturbance is:

[0056] Among them, the j-th state variable x j Contains the constant term C ji0 , independent frequency terms and the coupling frequency term yes Characteristic root, dmax is the maximum multiplicity of all repeated roots.

[0057] Taking the solution of m-domain 2-root as an example, the time domain analytical solution of the state quantity x can be obtained by using z=Rm. The solution is in the form of: In a system with two state variables, the state variable x i It contains constant term, independent frequency term and coupled frequency term, whose coefficients are C i0 , (C i1 +tC i1t ),(C i11 +tC i11t ), the system has new cross-scale characteristics. The constant term is caused by the non-zero derivatives of the state variables at the non-equilibrium point. The amplitudes of the independent frequency term and the coupled frequency term contain the time variable t. This is because after the introduction of nonlinear transformation, a special case of repeated roots appears in the z domain. The exponential decay is faster than the growth of the variable t, so when the real part of the characteristic root is less than 0, the modes are still convergent.

[0058] In one embodiment, S4 includes: analyzing characteristic roots in independent frequency terms and characteristic roots corresponding to coupled frequency terms to obtain cross-scale characteristics of the power system under transient disturbances.

[0059] Taking a system with two state variables as an example, the specific implementation of the present invention is described. For the present invention without repeated root phenomenon, object 1 is used for description; for the present invention with repeated root phenomenon, object 2 is used for description.

[0060] The differential equation of the x-domain state variable of plant 1 is: Expanding on the non-equilibrium point (1, 0.5), the disturbance of the system state variable x is (0.1, 0), and we get:

[0061]

[0062] Convert to the y domain and obtain:

[0063] Further nonlinear transformation is performed to obtain: Then the transformation to the z domain becomes: At this time, there are no repeated roots, and the differential equation in the m domain is obtained: Then solve the m-domain analytical expression: Then find m 10 and m 20 The x-domain perturbation is (0.1,0), according to Figure 1 Find m 10 =0,m 20 =0.1. So the solution is: From the inverse transformation from the m domain to the x domain, the solution is obtained in the form of:

[0064] Therefore, the system contains constant terms, independent frequency terms and coupled frequency terms at the non-equilibrium point. The constant term is caused by the non-zero derivatives of the state variables at the non-equilibrium point. 1 , including the frequency doubling term and the frequency coupling term, so this expression describes the multi-time scale characteristics of the system at the non-equilibrium point.

[0065] The differential equation of the x-domain state variable of plant 2 is: Expanding on the non-equilibrium point (1, 0.5), the disturbance of the system state variable x is (0.1, 0). The steps are similar to the above, so the differential equation in the z domain is directly given. At this time, the z domain contains repeated roots -1; we get

[0067] Solve the equation for this: By r 1 and r 2 The matrix consisting of right eigenvectors and generalized right eigenvectors is obtained, so it is converted to the m domain: Then solve the m-domain analytical expression: Then find m 10 and m 20 The x-domain perturbation is (0.1,0), according to Figure 1 Find m 10 =0.1, m 20 = 0. Therefore, the solution is: Converting to the x domain, the solution is in the form of:

[0069] Therefore, the system contains constant terms, independent frequency terms and coupled frequency terms at the non-equilibrium point. The constant term is caused by the non-zero derivatives of the state variables at the non-equilibrium point. 1 , including the frequency multiplication term and the frequency coupling term. Because of the appearance of repeated roots, the amplitudes of the independent frequency term and the coupled frequency term include the time constant t. The exponential decay is faster than the growth of the variable t, so when the characteristic root is less than 0, the modes are still convergent. This expression describes the multi-time scale characteristics of the system at the non-equilibrium point.

[0070] Example 2

[0071] This embodiment provides an analysis device for cross-scale interaction of power system under transient disturbance, including: a construction module, a decoupling module, a transformation module and an analysis module.

[0072] Among them, the construction module is used to construct the Taylor expanded differential equation of the x-domain state variables of the power system under transient disturbance, and perform linear coordinate transformation on the differential equation of the x-domain state variables to obtain the differential equation of the y-domain state variables containing second-order nonlinear terms; perform normal form nonlinear transformation on the differential equation of the y-domain state variables to eliminate nonlinear terms and convert it into the differential equation of the z-domain state variables.

[0073] The decoupling module is used to transfer the differential equations of the z-domain state variables to the decoupled domain m to obtain the analytical expressions of the m-domain state variables.

[0074] The transformation module is used to transform the analytical expressions of the m-domain state variables into the z-domain, y-domain and x-domain in turn, so as to convert the m-domain that does not contain actual physical meaning into the x-domain with actual physical meaning, and obtain the analytical expressions of the x-domain state variables of the power system under transient disturbances. The analytical expressions of the x-domain state variables are expanded to include constant terms, independent frequency terms and coupled frequency terms.

[0075] The analysis module is used to analyze independent frequency terms and coupled frequency terms to determine the cross-scale characteristics of the power system under transient disturbances.

[0076] Example 3

[0077] This embodiment provides a control system for an electric power system, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0078] Example 4

[0079] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above method are implemented.

[0080] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for analyzing cross-scale interactions of power systems under transient disturbances, characterized in that: include: S1: construct a nonlinear differential equation of the x-domain state variable with physical meaning for the power system under transient disturbance, perform a second-order Taylor expansion on the differential equation of the x-domain state variable at a non-equilibrium point, and then perform a linear coordinate transformation to obtain a differential equation of the y-domain state variable containing a second-order nonlinear term; perform a normal form nonlinear transformation on the differential equation of the y-domain state variable to eliminate the nonlinear term and convert it into a differential equation of the z-domain state variable; S2: transferring the differential equation of the z-domain state variable to the decoupled domain m to obtain an analytical expression of the m-domain state variable; S3: Inversely transforming the analytical expression of the m-domain state variable into the z-domain, y-domain and x-domain in sequence, so as to convert the m-domain that does not contain actual physical meaning into the x-domain with actual physical meaning, and obtain the analytical expression of the x-domain state variable of the power system under transient disturbance, wherein the analytical expression of the x-domain state variable is expanded to include a constant term, an independent frequency term and a coupled frequency term; S4: Analyze the independent frequency terms and the coupled frequency terms to determine the cross-scale characteristics of the power system under transient disturbances.

2. The method for analyzing cross-scale interactions of power systems under transient disturbances according to claim 1, characterized in that: The S1 includes: Construct the power system model under transient disturbance Differential equations of x-domain state variables with Taylor second-order expansion at nonequilibrium points Substituting x=Uy into get Let y = z + G(z), and take the derivative of y = z + G(z) to get Bring it in get Set (I+DG(z)) -1 =I-DG(z) into get Where P = U -1 B, O(3) is the third-order and higher-order terms, D is the Jacobian matrix operator, U is the right eigenvector matrix of x, H j is the Hessian matrix of the jth state variable, Λ is the characteristic root of matrix A λ1,λ2,···,λ n The diagonal matrix formed by Let F(z)=(DG(z))Λz-ΛG(z) and calculate and the differential equations for the z-domain state variables It is the coefficient matrix of z after merging -DG(z)P+Λz.

3. The method for analyzing cross-scale interactions of power systems under transient disturbances according to claim 2, characterized in that: The S2 includes: By transforming z = Rm, the differential equation of the state variable in the z domain is converted to the m domain, and the differential equation of the state variable in the m domain is obtained: R is The right eigenvector matrix composed of the right eigenvector and the generalized right eigenvector; The analytical expression of the m-domain state variable is obtained according to the solution formula of the linear non-homogeneous differential equation.

4. The method for analyzing cross-scale interactions of power systems under transient disturbances according to claim 3, characterized in that: In the S3: When the matrix When there is no repeated root, The jth analytical expression of the x-domain state variable of the power system under transient disturbance is Among them, the j-th state variable x j Contains the constant term C j0 , independent frequency terms and the coupling frequency term η1, η2…η n yes Characteristic root.

5. The method for analyzing cross-scale interactions of power systems under transient disturbances according to claim 3, characterized in that: In the S3: For the matrix The i-th heavy characteristic root η si The multiplicity is e si , then the corresponding analytical solution is: For the matrix Non-repeated characteristic roots, the corresponding analytical solution is: m i (t) = C i0 +C i1 e ηit ; When the matrix When there are i repeated roots, the jth analytical expression of the x-domain state variable of the power system under transient disturbance is: Among them, the j-th state variable x j Contains the constant term C ji0 , independent frequency terms and the coupling frequency term yes Characteristic root, dmax is the maximum multiplicity of all repeated roots.

6. The method for analyzing cross-scale interaction of power system under transient disturbance according to any one of claims 1 to 5, characterized in that: The S4 includes: The characteristic roots in the independent frequency terms and the characteristic roots corresponding to the coupled frequency terms are analyzed to obtain cross-scale characteristics of the power system under transient disturbances.

7. An analysis device for cross-scale interaction of power system under transient disturbance, characterized in that: include: A construction module is used to construct a Taylor-expanded differential equation of an x-domain state variable of an electric power system under transient disturbances, perform a linear coordinate transformation on the differential equation of the x-domain state variable to obtain a differential equation of a y-domain state variable containing a second-order nonlinear term; perform a normal form nonlinear transformation on the differential equation of the y-domain state variable to eliminate the nonlinear term and convert it into a differential equation of a z-domain state variable; A decoupling module, used for transferring the differential equation of the z-domain state variable to the decoupled domain m to obtain an analytical expression of the m-domain state variable; A transformation module, used for inversely transforming the analytical expression of the m-domain state variable into the z-domain, y-domain and x-domain in sequence, so as to convert the m-domain that does not contain actual physical meaning into the x-domain with actual physical meaning, and obtain the analytical expression of the x-domain state variable of the power system under transient disturbance, wherein the analytical expression of the x-domain state variable is expanded to include a constant term, an independent frequency term and a coupled frequency term; An analysis module is used to analyze the independent frequency terms and the coupled frequency terms to determine the cross-scale characteristics of the power system under transient disturbances.

8. A control system for an electric power system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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