Method, system and medium for determining power grid operation mode under voltage stability constraints

Abstract

The present invention discloses a method, system and medium for determining the operation mode of a power grid under voltage stability constraints; it relates to the technical field of dispatching and operating control of electric power systems; based on the existing technology, a multivariate nonlinear regression function is used to calculate the minimum voltage value; based on the minimum voltage value, the voltage trajectory is corrected according to a correction coefficient and a credibility coefficient; finally, based on the corrected voltage trajectory, a polynomial approximate equation of the system state concerned with respect to the total parameter is obtained; a large number of large power grid simulation calculations required for analyzing the voltage recovery of systems in different operation modes are reduced, and at the same time, a rapid analytical solution of the system voltage recovery characteristics under different operation modes and control parameter combinations is realized, and the operation mode with the worst system voltage stability characteristics is found, so as to obtain a grasp of the system stability characteristics and realize the safest operation mode arrangement.

Description

Technical Field

[0001] The present invention relates to the technical field of power system dispatching operation control, and in particular to a method, system and medium for determining a power grid operation mode under voltage stability constraints. Background Art

[0002] The voltage stability of the power system has always been an important factor limiting the power supply capacity of the power grid. The solution for power grid operators is to use commercial simulation software to analyze different combinations of operating modes and find the operating mode that meets the voltage recovery requirements stipulated in the safety and stability guidelines and has the largest power supply capacity. Analyzing the recovery characteristic curve of the key bus voltage of the power system under different operating mode arrangements is actually a parameterization problem. The difficulty lies in the fact that the arrangement of the operating mode is often discrete and nonlinear, with many combinations, which requires a lot of operating experience and often requires a lot of repeated simulation calculations of large power grids. In addition, in the operation mode arrangement of the power grid company, it is necessary to find the operation mode that reflects the most serious stability characteristics and arrange the operation mode with bottom-line thinking, which puts higher requirements on calculation and analysis. Summary of the invention

[0003] The purpose of the present invention is to provide a method, system and medium for determining the operation mode of a power grid under voltage stability constraints, so as to reduce the large amount of large power grid simulation calculations required for analyzing the voltage recovery of the system under different operation modes, and at the same time realize the rapid analytical solution of the system voltage recovery characteristics under different operation modes and control parameter combinations, and find the operation mode with the worst system voltage stability characteristics, so as to obtain a grasp of the system stability characteristics and realize the safest operation mode arrangement.

[0004] The present invention is achieved through the following technical solutions:

[0005] This solution provides a method for determining the operation mode of the power grid under voltage stability constraints, including:

[0006] S1, configuring parameter variables and parameter levels of total parameters of each operation mode, designing a test scheme of the operation mode based on an orthogonal test method, and performing redundancy deletion processing on the test scheme; the total parameter includes multiple sub-parameters;

[0007] S2, setting the points, and performing point allocation on the test plan after the redundancy removal process to obtain the final test plan;

[0008] S3, obtaining the voltage trajectory of the system state of interest changing with time under the operation mode of each distribution point;

[0009] S4, combining various operation modes: under the premise of consistent parameter levels, combining different values ​​of sub-parameters according to the traversal principle;

[0010] S5, using a multivariate nonlinear regression algorithm and voltage trajectory, calculating the regression coefficient of each sub-parameter with respect to the system voltage variable, and obtaining a multivariate nonlinear regression function;

[0011] S6, for different combinations obtained in step S4, the minimum voltage value is calculated using a multivariate nonlinear regression function; based on the minimum voltage value, the voltage trajectory is corrected according to a correction coefficient and a credibility coefficient;

[0012] S7, obtaining a polynomial approximation equation of the system state of interest with respect to the total parameter based on the corrected voltage trajectory.

[0013] A further optimization scheme is that step S2 includes:

[0014] S21, calculate the roots of the M-order Legendre polynomial {α1,α2…α M}, and convert the M-order Legendre polynomial roots to the total parameter range (λ min ,λ max ), we get M matching points {λ1,λ2…λ M}, that is, M Gaussian points;

[0015] S22, distribution point λ k (k=1,2…M) is the target level of the total parameter of the kth test plan, which is different from the total parameter level λ of the original test plan. k T There is a difference, and the minimum over / under allocation strategy is adopted to reduce λ k Assign the parameters involved in the k test solutions to obtain the final test solution {λ (1) ,λ (2) …λ (M)}, where: (k) =(λ 1k ,λ 2k ,…λ mk ),k=1,2…M.

[0016] A further optimization scheme is that the voltage trajectory of the system state of interest changing with time under the operation mode of each distribution point is obtained, including the method:

[0017] Based on the transient simulation program of commercial power system simulation software, the fault time and transient simulation parameters are set using the static and dynamic models of the studied power grid;

[0018] Set the parameter values ​​to λ (1) ,λ (2) …λ (M) , simulate sampling is performed under the operating mode with various parameter value settings to obtain the voltage trajectory of the system state of interest changing with time under the operating mode of each configuration point

[0019] A further optimization scheme is that step S4 includes the following sub-steps:

[0020] According to the traversal principle, the final test solution {λ (1) ,λ (2) …λ (M) Each scheme in} performs sub-parameter re-valuation and combination to keep the total parameter value level consistent, and m sub-parameters generate m combinations;

[0021] The most special sub-parameter value in the experimental scheme is traversed and assigned. If in the current scheme, λ 1k is the only minimum or maximum value based on its own maximum parameter value, then λ 1k The value of is exchanged with the remaining m-1 parameters to form the remaining m-1 solutions. Together with the original solution, there are a total of m traversal solutions, and finally m×M traversal solutions are formed:

[0022]

[0023] When sub-parameters with different parameter ranges are exchanged, the total parameter value level is maintained consistent based on the method of keeping missing values ​​consistent. For example, the maximum value of a parameter is 6, and the scheme setting value is 4.3, and the maximum value of another parameter is 18, and the scheme setting value is 18; when the two are exchanged, the new value of the former is 6, and the new value of the latter is 16.3, thus maintaining the consistency of the total parameter level of the new and old schemes.

[0024] A further optimization scheme is that step S5 includes the following process:

[0025] There are m sub-parameters, that is, using m quadratic equations, we follow the voltage value of the system state of interest and change over time, and perform nonlinear regression on the voltage values ​​under all configuration schemes at the same time to obtain the regression coefficients of each sub-parameter, and then form a regression function:

[0026] f(λ1,λ2,…λ m )=a1+b1λ1+c1λ1 2 +a2+b2λ2+c2λ2 2 …a m +b m λ m +c m λ m 2

[0027] Among them, a m , b m 、c m is the sub-parameter λ m The regression coefficient of .

[0028] A further optimization scheme is that for the different combinations obtained in step S4, the minimum voltage value is calculated using a multivariate nonlinear regression function, including the method:

[0029] For voltage trajectory The curve v generated for the kth (k=1…M) collocation point t,λ(k) At each moment, the m traversal solutions of the kth row are substituted into the regression function f(λ1,λ2,…λ m ), record the lowest voltage value

[0030] A further optimization scheme is that the voltage trajectory is corrected based on the minimum voltage value according to the correction coefficient and the credibility coefficient; including the method:

[0031] Get the system failure end time t clear , simulation curve end time t end ,calculate The curve from t clear to end The slope of the curve The maximum slope is Considering the confidence level, the corrected voltage curve is:

[0032]

[0033] Among them, η is the credibility coefficient considered in regression calculation, which usually takes a value of 0.6 to 0.8.

[0034] A further optimization scheme is that the polynomial approximation equation v in step S7 is t (λ) is:

[0035]

[0036] Where, j = 1…M; t = 0, Δt, 2Δt…; c t,j are polynomial coefficients; Φ k (λ) is a polynomial expression.

[0037] The present solution also provides a system for determining a power grid operation mode under voltage stability constraints, which is used to implement the above-mentioned method for determining a power grid operation mode under voltage stability constraints. The system includes:

[0038] The first configuration module is used to configure the parameter variables and parameter levels of the total parameters of each operation mode, design the test scheme of the operation mode based on the orthogonal test method, and perform redundancy deletion processing on the test scheme; the total parameter includes multiple sub-parameters;

[0039] The second configuration module is used to set the points and allocate the points to the test plan after the redundancy removal process to obtain the final test plan;

[0040] A first calculation module is used to obtain the voltage trajectory of the system state of interest changing with time under the operation mode of each distribution point;

[0041] The second calculation module is used to combine various operation modes: under the premise of consistent parameter levels, different values ​​of sub-parameters are combined according to the traversal principle;

[0042] The third calculation module is used to calculate the regression coefficient of each sub-parameter with respect to the system voltage variable by using a multivariate nonlinear regression algorithm and a voltage trajectory to obtain a multivariate nonlinear regression function;

[0043] A correction module is used to calculate the minimum voltage value for different combinations obtained in step S4 using a multivariate nonlinear regression function; based on the minimum voltage value, the voltage trajectory is corrected according to a correction coefficient and a credibility coefficient;

[0044] The output module is used to obtain a polynomial approximation equation of the system state of interest with respect to the total parameter based on the corrected voltage trajectory.

[0045] The present solution also provides a computer-readable medium having a computer program stored thereon, and the computer program is executed by a processor to implement the method for determining the operation mode of a power grid under voltage stability constraints as described above.

[0046] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0047] The present invention provides a method, system and medium for determining the operation mode of a power grid under voltage stability constraints; to reduce a large amount of large power grid simulation calculations required for analyzing the voltage recovery of the system under different operation modes, and at the same time to achieve rapid analytical solution of the system voltage recovery characteristics under different operation modes and control parameter combinations, to find the operation mode with the worst system voltage stability characteristics, to obtain a grasp of the system stability characteristics, and to achieve the safest operation mode arrangement. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0049] Figure 1 A flow chart of a method for determining a power grid operation mode under voltage stability constraints;

[0050] Figure 2 This is a schematic diagram of a certain power grid structure in Example 2;

[0051] Figure 3 It is a schematic diagram comparing the voltage curve after the correction of the point allocation scheme 1 of Example 2 with the original curve;

[0052] Figure 4 It is a schematic diagram comparing the voltage curve after correction and the original curve of the point matching scheme 2 of Example 2;

[0053] Figure 5 It is a schematic diagram comparing the voltage curve after correction and the original curve of the point matching scheme 3 of Example 2;

[0054] Figure 6 It is a schematic diagram comparing the voltage curve after the correction of the point 4 scheme of Example 2 with the original curve;

[0055] Figure 7 It is a schematic diagram comparing the voltage curve after the correction of the point 5 scheme of Example 2 with the original curve;

[0056] Figure 8 This is a schematic diagram of the voltage recovery value 2 seconds after the fault in Example 2. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0058] Example 1

[0059] The method for determining the operation mode of a power grid under voltage stability constraints provided in this embodiment is as follows: Figure 1 As shown, the steps include:

[0060] S1, configuring parameter variables and parameter levels of total parameters of each operation mode, designing a test scheme of the operation mode based on an orthogonal test method, and performing redundancy deletion processing on the test scheme; the total parameter includes multiple sub-parameters;

[0061] S11, initializing parameter configuration, selecting a total parameter λ related to the operation mode arrangement, wherein the total parameter λ is composed of m sub-parameter variables λ1, λ2, ...λ m ;(λ min ,λ max ) sets the total parameter range for the total parameter λ, and the total parameter range is determined by the sum of the sub-parameter variables, that is, λ min =∑(min(λ A ),min(λ B ),…),λ max=∑(max(λ A ),max(λ B ),…);

[0062] Set the level of each sub-parameter variable. The level of each sub-variable parameter is selected by the system operation mode;

[0063] As λ A represents the output of a power plant, which contains m units with a maximum output of P. Then the parameter λ A The levels are 0, P, 2P…mP; if λ A Represents the load level of a certain area. The parameter levels are set at equal intervals within the interval according to the maximum and minimum values ​​of the predicted load in the area.

[0064] S12, designing an orthogonal test scheme using the orthogonal test method according to the selected parameter variables and parameter levels;

[0065] S13, according to the designed test scheme, calculate the total parameter level value of each test scheme; when there are test schemes with the same total parameter level value, retain one test scheme according to the principle of involving as many sub-parameter variables as possible, delete other test schemes, and form several original test schemes after deletion and the total parameter level of each original test scheme;

[0066] S2, setting the points, and performing point allocation on the test plan after the redundancy removal process to obtain the final test plan;

[0067] S21, calculate the roots of the M-order Legendre polynomial {α1,α2…α M}, and convert the M-order Legendre polynomial roots to the total parameter range (λ min ,λ max ), we get M matching points {λ1,λ2…λ M}, that is, M Gaussian points; the matching points are converted according to the following formula:

[0068] S22, distribution point λ k (k=1,2…M) is the target level of the total parameter of the kth test plan, which is different from the total parameter level λ of the original test plan. k T is different, and the minimum over / under allocation strategy is adopted to reduce λ k Assign the parameters involved in the k test solutions to obtain the final test solution {λ (1) ,λ (2) …λ (M)}, where: (k) =(λ 1k ,λ 2k ,…λ mk ),k=1,2…M.

[0069] The minimum over / under allocation strategy is:

[0070] when Select the parameter reduction in the experimental scheme where the parameter level is not the minimum value in step S3.

[0071] when Select the parameter increase in the experimental scheme in step S3 where the parameter level is not the maximum value. when Maintain the original experimental plan.

[0072] S3, obtaining the voltage trajectory of the system state of interest changing with time under the operation mode of each distribution point;

[0073] Based on the transient simulation program of commercial power system simulation software, the fault time and transient simulation parameters are set using the static and dynamic models of the studied power grid;

[0074] Set the parameter values ​​to λ (1) ,λ (2) …λ (M) , simulate sampling is performed under the operating mode with various parameter value settings to obtain the voltage trajectory of the system state of interest changing with time under the operating mode of each configuration point

[0075] S4, combining the various operation modes: Under the premise of consistent parameter levels, combining different values ​​of sub-parameters according to the traversal principle; specifically, according to the traversal principle, the final test scheme {λ (1) ,λ (2) …λ (M) Each scheme in} performs sub-parameter re-valuation and combination to keep the total parameter value level consistent, and m sub-parameters generate m combinations;

[0076] The most special sub-parameter value in the experimental scheme is traversed and assigned. If in the current scheme, λ 1k is the only minimum or maximum value based on its own maximum parameter value, then λ 1k The value of is exchanged with the remaining m-1 parameters to form the remaining m-1 solutions. Together with the original solution, there are a total of m traversal solutions, and finally m×M traversal solutions are formed:

[0077]

[0078] When sub-parameters with different parameter ranges are exchanged, the total parameter value level is maintained consistent based on the method of keeping missing values ​​consistent. For example, the maximum value of a parameter is 6, and the scheme setting value is 4.3, and the maximum value of another parameter is 18, and the scheme setting value is 18; when the two are exchanged, the new value of the former is 6, and the new value of the latter is 16.3, thus maintaining the consistency of the total parameter level of the new and old schemes.

[0079] S5, using a multivariate nonlinear regression algorithm and voltage trajectory, calculating the regression coefficient of each sub-parameter with respect to the system voltage variable, and obtaining a multivariate nonlinear regression function;

[0080] There are m sub-parameters, that is, using m quadratic equations, we follow the voltage value of the system state of interest and change over time, and perform nonlinear regression on the voltage values ​​under all configuration schemes at the same time to obtain the regression coefficients of each sub-parameter, and then form a regression function:

[0081] f(λ1,λ2,…λ m )=a1+b1λ1+c1λ1 2 +a2+b2λ2+c2λ2 2 …a m +b m λ m +c m λ m 2

[0082] Among them, a m , b m 、c m is the sub-parameter λ m The regression coefficient of .

[0083] S6, for different combinations obtained in step S4, the minimum voltage value is calculated using a multivariate nonlinear regression function; based on the minimum voltage value, the voltage trajectory is corrected according to a correction coefficient and a credibility coefficient;

[0084] For voltage trajectory The curves generated for the kth (k=1…M) matching points At each moment, the m traversal solutions of the kth row are substituted into the regression function f(λ1,λ2,…λ m ), record the lowest voltage value

[0085] Get the system failure end time t clear , simulation curve end time t end ,calculate The curve from t clear to end The slope of the curve The maximum slope is Considering the confidence level, the corrected voltage curve is:

[0086]

[0087] Among them, η is the credibility coefficient considered in regression calculation, which usually takes a value of 0.6 to 0.8.

[0088] S7, obtaining a polynomial approximation equation of the system state of interest with respect to the total parameter based on the corrected voltage trajectory.

[0089] S71, selecting an M-order Legendre orthogonal polynomial as a basis function, and converting a variable range from (-1, 1) to a total parameter range by variable substitution transformation to obtain an orthogonal polynomial basis function;

[0090] The M-order Legendre orthogonal polynomial is selected as the basis function, and the variable range is converted from (-1, 1) to the total parameter range (λ min ,λ max ), we get the orthogonal polynomial basis function {Φ(λ)} M =Φ0(λ)…Φ k (λ)…Φ M (λ), k = 0…M;

[0091] Among them, the M-order Legendre orthogonal polynomial is obtained by looking up the table, and the variables are replaced according to the following formula:

[0092]

[0093] S72, calculating the orthogonal polynomial coefficients at each moment, and obtaining the polynomial approximate equation of the state variable of the system concerned with respect to the studied parameter according to the orthogonal polynomial coefficients;

[0094] Compute the coefficients of an orthogonal polynomial and compute the definite integral using the Gauss–Legendre quadrature method:

[0095] And calculate the definite integral Finally, calculate the polynomial coefficients at each moment Where j = 1…M, t = 0, Δt, 2Δt…, Δt is the simulation sampling step

[0096] Among them, using M Gaussian points λ k The Gauss-Legendre quadrature method (k=1,2…M) is used to calculate the definite integral: look up the table to obtain the integral coefficients {β1,β2…β M},pass:

[0097]

[0098] Polynomial approximation equation v t(λ) is:

[0099]

[0100] Where, j = 1…M; t = 0, Δt, 2Δt…; c t,j are polynomial coefficients; Φ k (λ) is a polynomial expression.

[0101] Example 2

[0102] This embodiment specifically implements Example 1, selects a power grid in a certain region of the country as the analysis object, and the brief structure is as follows Figure 2 As shown in the figure, the total output of the four power plants in the study area affects the curve of the key bus voltage after the fault. The simulation software is the power system analysis comprehensive program PSASP. In this area, the A, B, and C plants are each equipped with two units with a maximum output of 300,000 kWh and the same parameters. The installed capacity of the D plant is: 2 identical units with a maximum output of 300,000 kWh and 2 units with a maximum output of 600,000 kWh but different parameters. In this context, when designing the experiment, the output of the A, B, and C plants was set to two levels of 0 and 600,000 kWh, and the output of the D plant was set to four levels of 0, 6,000, 1.2, and 1.8 million kWh.

[0103] Initialization parameters, parameter level settings are shown in Table 1 below:

[0104] Table 1 Parameter level setting table

[0105]

[0106] The total parameter λ range is (λ min =0,λ max =360).

[0107] According to the number and level of sub-parameters, the test scheme is designed by orthogonal test as shown in Table 2 below:

[0108] Table 2 Experimental scheme designed using orthogonal experiment

[0109] Trial plan λ <![CDATA[λ A ]]> <![CDATA[λ B ]]> <![CDATA[λ C ]]> <![CDATA[λ D ]]> 1 0 0 0 0 0 2 180 0 0 60 120 3 180 60 0 60 60 4 300 60 60 0 180 5 240 0 0 60 180 6 120 0 60 0 60 7 180 60 0 0 120 8 180 60 60 60 0

[0110] According to the principle of involving as many sub-parameter variables as possible when the total parameter level value is the same, one scheme is retained and the other schemes are deleted. The resulting 5 experimental schemes are shown in Table 3:

[0111] Table 3 Test plan after deletion

[0112] Trial plan λ <![CDATA[λ A ]]> <![CDATA[λ B ]]> <![CDATA[λ C ]]> <![CDATA[λ D ]]> 1 0 0 0 0 0 2 120 0 60 0 60 3 180 60 0 60 60 4 240 0 60 60 120 5 300 60 60 0 180

[0113] Set the matching points, the roots of the 5th-order Legendre polynomial are -0.9061798, -0.5384693, 0, 0.5384693, 0.9061798, and the Gaussian points converted to the range of (0,360) are 16.887636, 83.075526, 180, 276.924474, 343.112364.

[0114] Point allocation, according to the minimum over / under allocation strategy, k The parameters involved in the k test schemes are assigned to obtain the final test scheme as shown in Table 4:

[0115] Table 4 Final test plan

[0116] Trial plan λ <![CDATA[λ A ]]> <![CDATA[λ B ]]> <![CDATA[λ C ]]> <![CDATA[λ D ]]> 1 16.89 16.89 0 0 0 2 83.08 0 60 0 23.08 3 180 60 0 60 60 4 276.92 0 60 60 156.92 5 343.11 60 60 43.11 180

[0117] Simulation sampling, using the comprehensive stability simulation program PSASP, based on the power grid system simulation. The output of the four power plants is set according to the five test schemes in Table 5 above, forming five operating modes, and then N-2 fault simulations of a key line are performed respectively, and the voltage curve of the key bus after the fault ends is recorded.

[0118] The operation mode arrangement combination, for the test scheme in Table 4, according to the traversal principle, forms 5×4 traversal schemes as shown in Table 5.

[0119] Table 5 Traversal plan table

[0120]

[0121] Using four quadratic equations, at each moment, nonlinear regression is performed according to the scheme parameter settings in Table 4 and the corresponding voltage values ​​to obtain the regression function:

[0122] f t (λ A ,λ B ,λ C ,λ D )=a 1t +b 1t λ A +c 1t λ A 2 +a 2t +b 2t λ B +c 2t λ B 2 +a 3t +b 3t λ C +c 3t λ C 2+a 4t +b 4t λ D +c 4t λ D 2

[0123] For the original voltage trajectory curve The curves generated for the kth (k=1…4) matching points At each moment, substitute the four traversal schemes in row k of Table 5 into the regression function f t (λ A ,λ B ,λ C ,λ D ), record the lowest voltage value

[0124] Usually the fault ends at 1.1 seconds, and the simulation curve ends at 5 seconds. The slope of the curve from 1.1 seconds to 5 seconds The maximum slope is Considering a certain degree of confidence, the final corrected voltage curve is:

[0125]

[0126] Among them, η=0.65.

[0127] The comparison between the corrected voltage curve and the original curve is as follows: Figure 3-Figure 7 shown.

[0128] Select the fifth-order Legendre polynomial and transform the variable range from (-1, 1) to (λ min ,λ max ), we get the orthogonal polynomial basis functions:

[0129]

[0130] To calculate the coefficients of the orthogonal polynomial, first look up the table to obtain the integral coefficients of the Gauss-Legendre quadrature formula for the 5-point collocation: 0.2369269, 0.4786287, 0.5688889, 0.4786287, 0.2369269. Use the following formula to solve <v t,λ ,Φ j (λ)>:

[0131]

[0132] Calculate the definite integral Finally, the polynomial coefficients at each moment are calculated based on the corrected voltage curve Where j=1…5.

[0133] Finally, we get the expression of the bus voltage v at different times t after the fault and the total output level λ of the four power plants, which is:

[0134]

[0135] According to the safety and stability guidelines, the voltage stability requirement is that the critical bus voltage recovers to 0.85 pu or above 2 seconds after the fault occurs. t (λ)≥0.85 can determine that the total parameter value range is λ>88, which is fed back to the operation arrangement of power plants A, B, C, and D. That is, at least three 300,000-kilowatt generators must be arranged to ensure voltage stability. In order to verify this conclusion, two 300,000-kilowatt units of any power plant are arranged to operate, and the voltage recovery value is observed 2 seconds after the fault, such as Figure 8 The results show that when two units are started, there is an operating mode where the voltage recovery does not meet the requirements. Therefore, the minimum startup requirement for power plants in this area should be the operation of three units with a capacity of more than 300,000 kilowatts to ensure the stability of the system voltage.

[0136] The scheme of this embodiment can directly provide analytical equation expressions of post-fault state variables under the influence of control parameters, quickly calculate transient characteristic curves of key state variables of the power system under different operating mode arrangements, thereby analyzing the safety and stability domain of the system and providing reliable operating plan arrangements.

[0137] Example 3

[0138] This embodiment provides a system for determining a power grid operation mode under voltage stability constraints, which is used to implement the method for determining a power grid operation mode under voltage stability constraints of embodiment 1. The system includes:

[0139] The first configuration module is used to configure the parameter variables and parameter levels of the total parameters of each operation mode, design the test scheme of the operation mode based on the orthogonal test method, and perform redundancy deletion processing on the test scheme; the total parameter includes multiple sub-parameters;

[0140] The second configuration module is used to set the points and allocate the points to the test plan after the redundancy removal process to obtain the final test plan;

[0141] A first calculation module is used to obtain the voltage trajectory of the system state of interest changing with time under the operation mode of each distribution point;

[0142] The second calculation module is used to combine various operation modes: under the premise of consistent parameter levels, different values ​​of sub-parameters are combined according to the traversal principle;

[0143] The third calculation module is used to calculate the regression coefficient of each sub-parameter with respect to the system voltage variable by using a multivariate nonlinear regression algorithm and a voltage trajectory to obtain a multivariate nonlinear regression function;

[0144] A correction module is used to calculate the minimum voltage value for different combinations obtained in step S4 using a multivariate nonlinear regression function; based on the minimum voltage value, the voltage trajectory is corrected according to a correction coefficient and a credibility coefficient;

[0145] The output module is used to obtain a polynomial approximation equation of the system state of interest with respect to the total parameter based on the corrected voltage trajectory.

[0146] Example 4

[0147] This embodiment provides a computer-readable medium having a computer program stored thereon. The computer program is executed by a processor to implement the method for determining the operation mode of a power grid under voltage stability constraints as in Embodiment 1.

[0148] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining a power grid operation mode under voltage stability constraints, characterized in that: include: S1, configuring parameter variables and parameter levels of total parameters of each operation mode, designing a test scheme of the operation mode based on an orthogonal test method, and performing redundancy deletion processing on the test scheme; the total parameter includes multiple sub-parameters; S2, setting the points, and performing point allocation on the test plan after the redundancy removal process to obtain the final test plan; Step S2 includes: S21, calculate the roots of the M-order Legendre polynomial {α1,α2…α M }, and convert the M-order Legendre polynomial roots to the total parameter range (λ min ,λ max ), we get M matching points {λ1,λ2…λ M }, that is, M Gaussian points; S22, distribution point λ k , k = 1, 2…M; that is, the target level of the total parameter of the kth test plan is equal to the total parameter level of the original test plan There is a difference, and the minimum over / under allocation strategy is adopted to reduce λ k Assign the parameters involved in the k test solutions to obtain the final test solution {λ (1) ,λ (2) …λ (M) }, where: (k) =(λ 1k ,λ 2k ,…λ mk ), k = 1, 2…M; S3, obtaining the voltage trajectory of the system state of interest changing with time under the operation mode of each distribution point; including the method: Based on the transient simulation program of commercial power system simulation software, the fault time and transient simulation parameters are set using the static and dynamic models of the studied power grid; Set the parameter values ​​to λ (1) ,λ (2) …λ (M) , simulate sampling is performed under the operating mode with various parameter value settings to obtain the voltage trajectory of the system state of interest changing with time under the operating mode of each configuration point S4, combining various operation modes: under the premise of consistent parameter levels, combining different values ​​of sub-parameters according to the traversal principle; step S4 includes the following sub-steps: According to the traversal principle, the final test solution {λ (1) ,λ (2) …λ (M) Each scheme in} performs sub-parameter re-valuation and combination to keep the total parameter value level consistent, and m sub-parameters produce m combinations; If in the current scheme, λ 1k is the only minimum or maximum value based on its own maximum parameter value, then λ 1k The value of is exchanged with the remaining m-1 parameters to form the remaining m-1 solutions. Together with the original solution, there are a total of m traversal solutions, and finally m×M traversal solutions are formed: When sub-parameters with different parameter ranges are exchanged, the overall parameter value level is maintained consistent based on the method of keeping missing values ​​consistent; S5, using a multivariate nonlinear regression algorithm and a voltage trajectory, calculating the regression coefficient of each sub-parameter with respect to the system voltage variable, and obtaining a multivariate nonlinear regression function; step S5 includes the following process: There are m sub-parameters, that is, using m quadratic equations, we follow the voltage value of the system state of interest and change over time, and perform nonlinear regression on the voltage values ​​under all configuration schemes at the same time to obtain the regression coefficients of each sub-parameter, and then form a regression function: f(λ1,λ2,…λ m )=a1+b1λ1+c1λ1 2 +a2+b2λ2+c2λ2 2 ...a m +b m l m +c m l m 2 Among them, a m , b m 、c m is the sub-parameter λ m The regression coefficient of S6, for different combinations obtained in step S4, using a multivariate nonlinear regression function to calculate the lowest voltage value; based on the lowest voltage value, the voltage trajectory is corrected according to a correction coefficient and a credibility coefficient; for different combinations obtained in step S4, using a multivariate nonlinear regression function to calculate the lowest voltage value, including a method: For voltage trajectory The curves generated for the kth, k=1…Mth matching points are At each moment, the m traversal solutions of the kth row are substituted into the regression function f(λ1,λ2,…λ m ), record the lowest voltage value Based on the minimum voltage value, the voltage trajectory is corrected according to the correction coefficient and the credibility coefficient; including the method: Get the system failure end time t clear , simulation curve end time t end ,calculate The curve from t clear to end The slope of the curve The maximum slope is Considering the confidence level, the corrected voltage curve is: Among them, η is the credibility coefficient considered in regression calculation; S7, obtaining a polynomial approximation equation of the system state of interest with respect to the total parameter based on the corrected voltage trajectory.

2. The method for determining the operation mode of a power grid under voltage stability constraints according to claim 1, characterized in that: The polynomial approximation equation v in step S7 t (λ) is: Where, j = 1…M; t = 0, Δt, 2Δt…; c t,j are polynomial coefficients; Φ k (λ) is a polynomial expression.

3. A system for determining the operation mode of a power grid under voltage stability constraints, characterized in that: Used to implement the method for determining the operation mode of a power grid under voltage stability constraints as described in claim 1 or 2, the system comprises: The first configuration module is used to configure the parameter variables and parameter levels of the total parameters of each operation mode, design the test scheme of the operation mode based on the orthogonal test method, and perform redundancy deletion processing on the test scheme; the total parameter includes multiple sub-parameters; The second configuration module is used to set the points and allocate the points to the test plan after the redundancy removal process to obtain the final test plan; A first calculation module is used to obtain the voltage trajectory of the system state of interest changing with time under the operation mode of each distribution point; The second calculation module is used to combine various operation modes: under the premise of consistent parameter levels, different values ​​of sub-parameters are combined according to the traversal principle; The third calculation module is used to calculate the regression coefficient of each sub-parameter with respect to the system voltage variable by using a multivariate nonlinear regression algorithm and a voltage trajectory to obtain a multivariate nonlinear regression function; A correction module is used to calculate the minimum voltage value for different combinations obtained in step S4 using a multivariate nonlinear regression function; based on the minimum voltage value, the voltage trajectory is corrected according to a correction coefficient and a credibility coefficient; The output module is used to obtain a polynomial approximation equation of the system state of interest with respect to the total parameter based on the corrected voltage trajectory.

4. A computer readable medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement the method for determining the operation mode of a power grid under voltage stability constraints as claimed in claim 1 or 2.

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