Power system dynamic adaptive calculation method

Abstract

The invention discloses a dynamic adaptive calculation method for a power system, and belongs to the field of power systems, and the method carries out the adaptive calculation according to an analytical solution of an x-domain state variable of the power system, thereby judging and expanding a regular calculation step length according to a nonlinear intensity quantitative index. The calculation amount is reduced while the dynamic analysis precision is guaranteed, and the calculation efficiency is improved; the nonlinear characteristics of the dynamic unbalance point of the power system are considered, and the application range near the regular unbalance point can be clearly expanded, so that the calculation efficiency is improved while the precision is guaranteed; and realizing nonlinear analysis in the dynamic process of the system through a state variable analytic expression.

Description

Technical Field

[0001] The present invention belongs to the field of power systems, and more specifically, relates to an adaptive calculation method for power system dynamics. Background Art

[0002] Nonlinear characteristics pose a great challenge to the safe and stable operation of power systems. In a traditional power system dominated by synchronous machines, under heavy load conditions, the nonlinear intensity increases, and there is nonlinear interaction in system modes. With the continuous increase in the proportion of new energy, the system nonlinearity is significantly enhanced, and the nonlinearity of the system cannot be ignored. In a traditional power system, under heavy load conditions where the tie-line power is large, the system nonlinearity increases, and there is interaction in the basic modes. Control strategies designed based on linear methods are not conducive to system stability. New energy power electronic devices contain many nonlinear links, such as coordinate changes brought by phase-locked loops and virtual synchronous control loops, active and reactive power calculations, etc. Therefore, power electronic power systems have strong nonlinear characteristics.

[0003] Currently, the research on the nonlinear dynamics of power systems mainly analyzes the nonlinear interactions of the system based on reduced-order models. However, simply ignoring the coupling of each controller and each power electronic device to reduce the system order cannot fully characterize the dynamic characteristics of the system, resulting in inconsistent results between the analysis of the power system nonlinearity and the actual engineering results.

[0004] Traditional normal form analysis methods can analyze the mode-coupling nonlinear characteristics of the system at the equilibrium point and quantify the system nonlinear intensity, but they are only limited to the analysis of the power system steady state. Chinese Patent with publication number CN109617466A discloses a nonlinear modeling method for a switched reluctance motor complex power electronic system based on a deformed function Sigmoid interpolation method. First, using the flux linkage value of a switched reluctance linear motor, a new quasi-linear model of the magnetization curve is proposed and analyzed. Secondly, the entire magnetization curve is interpolated using the deformed function Sigmoid, several key phase current curves are sampled, and the corresponding phase winding modules are given. This method proposes a new nonlinear modeling method that can be used for the nonlinear modeling of switched reluctance motors; however, this method only models the motor and cannot quantify the nonlinear intensity of the motor. Chinese Patent with publication number CN117910219A discloses a high-precision dynamic frequency simulation method and system for a power system under nonlinear disturbances, which uses an operator splitting method to establish a frequency accurate value model and corrects the model based on a spectral deficit correction method; however, this method is based on the measured grid frequency and only analyzes the nonlinear characteristics brought by the frequency and cannot calculate the power system dynamics. Summary of the Invention

[0005] In view of the above deficiencies or improvement requirements of the prior art, the present invention provides an adaptive calculation method for power system dynamics, which can reduce the calculation amount while ensuring the analysis accuracy and improve the calculation efficiency.

[0006] To achieve the above object, according to the first aspect of the present invention, there is provided an adaptive calculation method for power system dynamics, including:

[0007] S1. Let g = 1;

[0008] S2. Randomly set the g-th calculation step size T g ;

[0009] S3. According to the final value x 1 +T 2 +…+Tg- 1 of the state variable of the power system at time T i (T g-1 ), calculate the initial value of the state variable at time T 1 +T 2 +…+T g-1 +T g , and calculate the comprehensive nonlinear strength I of the power system at time T 1 +T 2 +…+T g-1 +T g according to the initial value and the formula 3 ; where I 1 (i), I 2 are the first-class and second-class nonlinear strengths respectively;

[0010] S4. Judge whether I 3 is greater than its upper limit value I 3maxset . If so, update T g to T g / 2 and return to S3 until I 3 is not greater than I 3maxset , then enter S5; otherwise, directly enter S5;

[0011] S5. Judge whether I 3 is less than its lower limit value I 3minset . If so, let T g be updated to 2T g and return to S3 until I 3 is not less than I 3minset , then enter S6; otherwise, directly enter S6;

[0012] S6. Judge whether the current total calculation duration T = T 1 +T 2 +…+T gIs it greater than Tset? If so, output the current time-domain analytical solution of the state variable; otherwise, use the current time-domain analytical solution of the state variable as the final value of the state variable of the power system at T 1 +T 2 +…+T g-1 +T g When the final value is reached, let g = g + 1 and return to S2.

[0013] According to the second aspect of the present invention, there is provided an electronic device, including: a computer-readable storage medium and a processor;

[0014] The computer-readable storage medium is used to store executable instructions;

[0015] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the method as described in the first aspect.

[0016] According to the third aspect of the present invention, there is provided a computer-readable storage medium, and the computer-readable storage medium stores computer instructions, and the computer instructions are used to cause the processor to execute the method as described in the first aspect.

[0017] According to the fourth aspect of the present invention, there is provided a computer program product, including a computer program or instructions, and when the computer program or instructions are executed by a processor, the method as described in the first aspect is implemented.

[0018] Generally speaking, compared with the prior art through the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0019] The method provided by the present invention calculates the dynamics of the power system based on the adaptive non-linear strength. By performing a second-order Taylor expansion on the non-linear differential equation of the x-domain state variable of the power system after perturbation at a non-equilibrium point, the non-linear differential equation of the x-domain state variable is sequentially transformed to the y-domain, z-domain, and m-domain to obtain the analytical expression of the m-domain state variable; the second-order Taylor expansion includes the second-order non-linear term matrix compared with the first-order Taylor expansion, and can more accurately describe the strong non-linear dynamic behavior of the power system. Further, the analytical expression of the m-domain state variable is sequentially inverse-transformed to the z-domain, y-domain, and x-domain to obtain the analytical expression of the x-domain state variable of the power system after perturbation; and adaptive calculation is performed according to this expression, so as to judge and expand the normal form calculation step according to the non-linear strength quantization index, thereby reducing the calculation amount while ensuring the analysis accuracy and improving the calculation efficiency; considering the non-linear characteristics of the non-equilibrium point of the power system, it can clarify the applicable range near the non-equilibrium point of the extended normal form, thereby improving the calculation efficiency while ensuring the accuracy; non-linear analysis during the dynamic process of the system is realized through the analytical formula of the state variable. Description of the Drawings

[0020] Figure 1 Flow chart of the dynamic non - linear strength adaptive calculation method for the power system provided by the embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the power angle and rotational speed waveforms of the synchronous machine electromagnetic transient (EMT) after being disturbed and the power angle and rotational speed waveforms output by using the method provided by the present invention;

[0022] Figure 3 Schematic diagram of the calculation step size obtained by using the method provided by the embodiment of the present invention. Specific implementation mode

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to 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 used 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.

[0024] The prior art usually converts a time - varying non - linear system into a time - invariant linear system to obtain a numerical solution, and cannot quantify the non - linear strength of the system, so it cannot accurately evaluate the non - linear dynamic process of the power system. With the continuous increase in the proportion of new energy equipment in the power - electronic power system, the power system shows high - order and strong non - linear characteristics. Based on this, the embodiment of the present invention provides an adaptive calculation method for the power system dynamics, including:

[0025] S1, let g = 1;

[0026] S2, randomly set the g - th calculation step size T g ;

[0027] S3, according to the final value x 1 +T 2 +…+Tg - 1 of the state variable of the power system at time T i (T g-1 ), calculate the initial value of the state variable of the power system at time T 1 +T 2 +…+T g-1 +T g , and calculate the comprehensive non - linear strength I of the power system at time T g according to the initial value and the formula 3 ;

[0028] S4, judge whether I 3 is greater than its upper limit value I 3maxset . If so, update T g to T gReturn to S3 after / 2 until I 3 Not greater than I 3maxset , enter S5; otherwise directly enter S5;

[0029] S5, judge I 3 Whether it is less than its lower limit value I 3minset , if so, then set T g Update to 2T g Then return to S3 until I 3 Not less than I 3minset , enter S6; otherwise directly enter S6;

[0030] S6, judge the current total calculation duration T = T 1 +T 2 +…+T g Whether it is greater than Tset, if so, output the current time-domain analytical solution of the state variable; otherwise use the current time-domain analytical solution of the state variable as the power system at T 1 +T 2 +…+T g-1 +T g The final value of the state variable at time, let g = g + 1, return to S2.

[0031] Preferably, to improve the calculation efficiency, when g ≠ 1, in step S2, T g = T g-1 .

[0032] The method provided by the present invention, on the basis of the traditional normal form analysis method, proposes an extended normal form analysis method, further calculates the analytical expression of the power system state variable in the time domain based on the second-order Taylor expansion of the non-equilibrium point, provides non-linear indexes for the equilibrium point and the non-equilibrium point, and proposes a non-linear strength adaptive calculation method according to this index. Specifically include:

[0033] 1. Extended normal form analysis method and non-linear index

[0034] For the power system described by differential-algebraic equations, assume there are n state variables

[0035]

[0036] Perform a second-order Taylor expansion on the above formula at the non-equilibrium point x 0 to obtain

[0037]

[0038] where B is a constant matrix, A is the Jacobian matrix, and H i is the Hessian matrix, and B, A, and H i all include the information of x 0 .

[0039] Substituting \(x = Uy\) into (2) gives

[0040] Set \(y = z+G(z)\), and taking the derivative of \(y = z + G(z)\) gives Substituting it into gives

[0041] Substituting the set \((I + DG(z))\) -1 \(= I - DG(z)\) into gives

[0042] where \(P = U\) -1 B, \(O(3)\) are third - order and higher - order terms, \(D\) is the Jacobian matrix operator, \(U\) is the right eigenvector matrix of matrix \(A\), \(H\) j is the Hessian matrix of the \(j\) - th state variable, \(\Lambda\) is the diagonal matrix composed of the eigenvalues \(\lambda\) 1 , \(\lambda\) 2 , \(\cdots\), \(\lambda\) n ;

[0043] Let \(F(z)=(DG(z))\Lambda z-\Lambda G(z)\) and calculating gives \(V = U\) -1 , \(V\) ji is the element in the \(j\) - th row and \(i\) - th column of matrix \(V\), and the differential equation of the state variable in the \(z\) - domain is the coefficient matrix of \(z\) after combining \(-DG(z)P+\Lambda z\).

[0044] By transforming \(z = Rm\), the differential equation of the state variable in the \(z\) - domain is converted to the \(m\) - domain, obtaining the differential equation of the state variable in the \(m\) - domain: \(R\) is the right eigenvector matrix composed of right eigenvectors; Solving gives the analytical expression of the state variable in the \(m\) - domain at the non - equilibrium point. Then, through the inverse transformation, the analytical solution of the state variable in the \(x\) - time domain is

[0045]

[0046] The first term on the right - hand side of the equation is the basic mode, and the second term is the coupling mode. \(U\) is the right eigenvector matrix of matrix \(A\), \(u\) ij is the element in the \(i\) - th row and \(j\) - th column of matrix \(U\). is the non - linear transformation coefficient obtained according to the above extended normal form method, \(n\) is the number of state variables, \(i = 1,2,\cdots,n\);

[0047]

[0048] where \(q\)a , q b are the a-th and b-th terms in element Q respectively, where Q = R -1 P, η 1 , η 2 , …, η n is the eigenroot of; m i0 is the initial value of the i-th element of m. The initial values of each element in m are calculated according to the final values of the state variables of the power system at the previous calculation step and the relationship between m and x

[0049] R is the right eigenvector in the z-domain of the extended normal form method, r jd , r ka , r lb are the elements in the j-th row and d-th column, k-th row and a-th column, and l-th row and b-th column of matrix R respectively. The Q element is a constant matrix in the m-domain, q a , q b are the a-th and b-th terms in element Q respectively, η 1 , η 2 … η n is the eigenroot in the z-domain, m i0 is the initial value of the i-th element in the m-domain

[0050] Perform a second-order Taylor expansion on the nonlinear differential equation of the x-domain state variables of the perturbed power system at the non-equilibrium point, so as to transform the nonlinear differential equation of the x-domain state variables to the y-domain, z-domain, and m-domain in sequence to obtain the analytical expression of the m-domain state variables; the second-order Taylor expansion includes the second-order nonlinear term matrix compared with the first-order Taylor expansion, and can more accurately describe the strong nonlinear dynamic behavior of the power system. Further, the analytical expression of the m-domain state variables is inversely transformed to the z-domain, y-domain, and x-domain in sequence to obtain the analytical expression of the x-domain state variables of the perturbed power system

[0051] For the above time-domain analytical expressions, obtain the nonlinear strength index. The first type is the time-domain nonlinear terms caused by the nonlinear transformation G(z) itself, and the second type is the basic mode changes caused by the Jacobian matrix DG(z) of the nonlinear transformation

[0052] The first type is divided into two kinds. The first kind is the coupling of basic modes. The existence of this kind of nonlinear phenomenon is independent of the system trajectory, that is, it exists at both the equilibrium point and the non-equilibrium point. At the equilibrium point, it is reflected as the coupling of basic modes λ k ±λ l , λ k and λ l represent the k-th and l-th linear eigenroots respectively. At the non-equilibrium point, it reflects the coupling of basic modes η a ±η b , η a and η bRepresent the a-th and b-th non-linear characteristic roots respectively. The second type of non-linearity is manifested as the coupling related to the constant term of the non-equilibrium point, including the coupling between the basic mode and the constant term, and the coupling between constant terms. The coupling between the basic mode and the constant term, and the coupling between constant terms, such as and C ab0 , this non-linear phenomenon is specific to the non-equilibrium point. The second type of non-linearity is manifested as the change of the basic mode. At the equilibrium point, the basic mode of the system remains unchanged. However, at the non-equilibrium point, the basic mode of the system changes. The non-linearity at the non-equilibrium point will cause the basic mode of the system to change, and this type of non-linear phenomenon is specific to the non-equilibrium point.

[0053] For non-linear phenomena, non-linear indices are proposed respectively:

[0054] (1) The first type of non-linear strength index

[0055] The first type of non-linearity is caused by non-linear transformation, and its non-linear strength calculation formula is as follows:

[0056]

[0057] (2) The second type of non-linear strength index

[0058] The second type of non-linearity is caused by the Jacobian matrix of non-linear transformation. The linear characteristic roots and non-linear characteristic roots are different. Considering the influence of eigenvalues on different time scales, the linear and non-linear characteristic roots are normalized, and the characteristic root offset index is obtained according to the following formula:

[0059]

[0060] (3) The comprehensive non-linear strength index

[0061] Combining two types of non-linear phenomena with the first type and the second type of non-linear strength indices, a comprehensive non-linear strength index is proposed to evaluate the calculation step size T of the extended normal form step .

[0062]

[0063] 2. Adaptive calculation method based on non-linear strength

[0064] According to the analytical expression in the time domain, an adaptive calculation method based on non-linear strength is proposed. This algorithm can be applied to variable step size and fixed step size. Assume that the calculation step size for each time is T 1 、T 1 、…、T o , if the variable step size algorithm is adopted, different calculation step sizes are selected according to the system structure and initial values. If the fixed step size algorithm is adopted, then T 1 =T 2 =…=To 。

[0065] The fixed-step algorithm is a special case of the variable-step algorithm, so the variable-step algorithm is taken as an example for illustration.

[0066] According to the mathematical structure of the power system (i.e., the state variable description equation) and the extended normal form method provided by the present invention, the calculation formula for the time-domain analytical solution of the state variables is obtained, that is, formula (3). Randomly select the first calculation step size T 1 , and substitute the initial value of the state variables of the system at time t = 0 and t = T 1 into formula (3) to obtain the time-domain analytical solution of the i-th state variable of the power system at time t = T 1 :

[0067]

[0068] Then, according to the calculation formula for the nonlinear strength index, the first type of nonlinear strength I 1 , the second type of nonlinear strength I 1 , and the comprehensive nonlinear strength I 2 at time t = T 3 are obtained.

[0069] Judge whether the comprehensive nonlinear strength I 3 is greater than I 3maxset . If so, update T 1 to T 1 / 2, substitute it back into the state variable analytical expression, and calculate the new nonlinear index I 3 ; otherwise, judge whether I 3 is less than I 3minset . If so, update T 1 to 2×T 1 , substitute it back into the state variable analytical expression, and calculate the new nonlinear index I 3 ; if I 3 is greater than I 3minset , then further judge whether the total time T is greater than T set . If so, output the waveforms of the n state variables of the power system; otherwise, let T 2 = T 1 , substitute the final value x 1 of the i-th state variable of the power system at t = T i (T 1 ) and t = T 2 into formula (3), and calculate the initial value of the time-domain analytical solution of the i-th state variable at time t = T 1 + T 2 :

[0070]

[0071] Then, similar to the previous step, according to the non-linear strength index calculation formula, the comprehensive non-linear strength I at time t = T 1 +T 2 is obtained, and it is judged whether it is between I 3 and I 3minset and I 3maxset . If it is not within this range, adaptive compensation adjustment is performed to adjust T 2 . Otherwise, it is judged whether the total time T is greater than Tset. If so, the waveforms of n state variables of the power system are output. Otherwise, let T 3 =T 2 . Substitute the final value x 1 +T 2 of the i-th state variable of the power system at t = T i (T 2 ) and t = T 3 into formula (3) to calculate the initial value of the time-domain analytical solution of the i-th state variable at t = T 1 +T 2 +T 3 , and continue to repeat the above steps.

[0072] ……

[0073] The final value x i (T s ) of the state variable obtained by the s-th iteration calculation is the initial value of the state variable for the (s + 1)-th iteration calculation. That is, substitute the final value x 1 +T 2 +…+Ts of the i-th state variable of the power system at t = T i (T s ) and t = T s+1 into formula (3) to calculate the initial value of the time-domain analytical solution of the i-th state variable of the power system at T 1 +T 2 +…+T s +T s+1 :

[0074]

[0075] Then, according to the non-linear strength index calculation formula, the comprehensive non-linear strength at time t = T 1 +T 2 +…+T s +T s+1 is obtained, and it is judged whether the random value of T s+1 satisfies the range of the comprehensive non-linear strength. If it does not meet the requirements, the value of T s+1 is adaptively compensated and adjusted to meet the range of the comprehensive non-linear strength. Next, it is judged whether the total calculation time has reached Tset If the waveforms of the n state variables of the output power system are to be obtained, the waveforms of the state variables in each time period are connected to obtain the time-domain diagram of the state variables; otherwise, the next calculation is performed.

[0076] I 3maxset 、I 3minset They are selected according to the actual power system structure and calculation requirements. For example, if high calculation accuracy is required, then smaller I 3maxset and I 3minset are taken; T set is set according to the required analysis duration.

[0077] It can be understood that Equation (3) is to perform Taylor second-order expansion on the state variables of the power system at the non-equilibrium point (i.e., the final value of the time-domain analytical solution of the state variables in the previous calculation step), and sequentially transform from the x domain to the y domain, z domain, and m domain to obtain the analytical expression of the state variables in the m domain, and then sequentially inverse-transform the analytical expression of the state variables in the m domain to the z domain, y domain, and x domain to obtain the analytical expression of the state variables in the x domain of the power system. That is, in each iterative calculation, since the final value of the analytical solution of the state variables obtained in the previous iterative calculation is used, that is, Taylor second-order expansion is performed at this final value point and then domain transformation is performed. Therefore, in each iterative calculation, u ij 、 C d0 、C d1 、C ab0 、C ab1 、C ba1 、C ab2 etc. are all different.

[0078] The method provided by the present invention is described below with a specific example.

[0079] Select a power system with a single synchronous machine and a long transmission line. The description equations of its state variables δ and ω are:

[0080]

[0081] Among them, δ is the system power angle, ω is the synchronous speed, and D is the damping. When the system is in a steady state, the power angle is 53.8°, and the power angle derivative is 0° / s. An adaptive calculation method based on the extended normal form and non-linear strength is adopted.

[0082] Under the initial conditions, the power angle is 49.8°, the synchronous speed is 64.3° / s, and the electromagnetic transient simulation step size is 1e-5 s. After being disturbed, the waveforms of the electromagnetic transient EMT power angle and speed of the synchronous machine are as shown by the black line in Figure 2 , and the waveforms output by the ENFM method provided by the present invention are as shown by the red dotted line in Figure 2 .

[0083] As can be seen from Figure 2 , the non-linear strength adaptive calculation method provided by the present invention can accurately estimate the applicable range near the non-equilibrium point of the extended normal form, where the selection of T step is as follows Figure 3 shown Figure 3 There are 12 points in total, that is, T = T 1 + T 2 + … + T 12 = 7.05 s. Thus, it can be seen that the method provided by the present invention can ensure the calculation accuracy while reducing the number of calculations and improving the calculation efficiency of ENFM.

[0084] An embodiment of the present invention provides an electronic device, including: a computer-readable storage medium and a processor;

[0085] The computer-readable storage medium is used to store executable instructions;

[0086] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the method described in any of the above embodiments.

[0087] An embodiment of the present invention provides a computer-readable storage medium, which stores computer instructions for causing a processor to execute the method described in any of the above embodiments.

[0088] An embodiment of the present invention provides a computer program product, including a computer program or instructions, and when the computer program or instructions are executed by a processor, the method described in any of the above embodiments is implemented.

[0089] It is easy for those skilled in the art to understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. An adaptive calculation method for power system dynamics, characterized in that: include: S1, set g = 1; S2, randomly set the g-th calculation step length T g ; S3, based on the final value x of the state variable of the power system at T1+T2+…+Tg-1 i (T g-1 ), calculate its g-1 +T g The initial value of the state variable at time , and according to the initial value and formula Calculate the power system at T1+T2+…+T g-1 +T g The comprehensive nonlinear intensity I3 when , where I1(i) and I2 are the first and second type of nonlinear intensity respectively; S4, determine whether I3 is greater than its upper limit value I 3maxset If so, then T g Update to T g / 2 and then return to S3 until I3 is no greater than I 3maxset , enter S5; otherwise, directly enter S5; S5, determine whether I3 is less than its lower limit I 3minset If so, then let T g Updated to 2T g Then return to S3 until I3 is not less than I 3minset , enter S6; otherwise, directly enter S6; S6, determine the current total calculation time T = T1 + T2 + ... + T g Is it greater than Tset? If so, output the current time domain analytical solution of the state variable; otherwise, use the current time domain analytical solution of the state variable as the power system at T1+T2+…+T g-1 +T g The final value of the state variable at time , let g = g + 1, and return to S2.

2. The method according to claim 1, characterized in that The power system is T1+T2+…+T g-1 +T g The initial value of the state variable is t = T g Substitute the following calculation formula to calculate: Among them, u ij is the i-row and j-column element in the matrix U, where U is the state variable x = [x1,…,x n ] T At T1+T2+…+T g-1 The final value x of the state variable i (T g-1 ) is the right eigenvector matrix of the Jacobian matrix A in the Taylor first-order expansion at the point; It is C j The element in row k and column l in k ,λ l ,λ j is the characteristic root of matrix A, V=U -1 , V ji is the j-row and i-column element in the matrix V, and n is the number of state variables in the power system; r jd 、r ka 、r lb are the elements in row j, column d, row k, column a, and row l, column b of the matrix R. R is The right eigenvector matrix of is the coefficient matrix of z after merging -DG(z)P+Λz, y=z+G(z), x=Uy, D is the Jacobian matrix operator, P=U -1 B;q a ,q b are the ath and bth items in element Q, respectively, Q=R -1 P,η1,η2,…,η n yes The characteristic root, m i0 is the initial value of the ith element of m, z = Rm, y = [y1,…,y n ] T ,z=[z1,…,z n ] T ,m=[m1,…,m n ] T .

3. The method according to claim 2, characterized in that λ1,λ2,···,λ n is the characteristic root of matrix A.

4. The method according to claim 1, characterized in that When g≠1, in step S2, T g =T g-1 .

5. An electronic device, characterized in that: include: A computer readable storage medium and a processor; The computer-readable storage medium is used to store executable instructions; The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the method according to any one of claims 1 to 4.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to execute the method according to any one of claims 1 to 4.

7. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method according to any one of claims 1 to 4 is implemented.

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