Power system edge weight coefficient calculation method and system

Abstract

The invention provides a power system edge weight coefficient calculation method and system, and relates to the technical field of power system parameter calculation, and the method comprises the steps: calculating a node impedance matrix of a topological structure, and calculating a first power variation and a second power variation according to elements in the node impedance matrix, wherein the first power variable quantity and the second power variable quantity are power changes caused on different lines when the source load node changes the power by a first quantity value; a correlation coefficient is obtained according to the first power variation and the second power variation, and the correlation coefficient is the relation of the power variation between two different lines when the source load node changes the power; a third power variation is calculated according to the correlation coefficient, and the third power variation is power variation caused on all the lines when the power of any line is changed by the second magnitude; and performing linear weighted stacking on the third power variable quantity to obtain an edge weight coefficient. The calculation is carried out without using weights, so that the accuracy of the calculation result can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of power system parameter calculation, and in particular to a method and system for calculating edge weight coefficients of a power system. Background Art

[0002] As the core part of energy supply, the power system continues to expand in scale and its structure becomes increasingly complex. In order to ensure the stability and efficiency of power supply and effectively manage large-scale power systems, the power system will be reasonably divided into regions based on the principle of strong coupling within regions and weak coupling between regions.

[0003] However, when partitioning a complex network power system, it is necessary to calculate the edge weight coefficient of the line. The edge weight coefficient is a key indicator to measure the importance of the line in the power system, which is directly related to the rationality and effectiveness of the partition. In order to take into account the operating status and topological structure characteristics of the power system, a weighted index is usually used to define the line edge weight coefficient. The calculation of the edge weight coefficient is shown in the following formula: Line edge weight coefficient = ω × power system operating status index + (1-ω) edge betweenness index. This calculation method combines the power system operating status index and the edge betweenness index, and balances the influence of the two by adjusting the weight ω.

[0004] Although this method reflects the comprehensive characteristics of the line to a certain extent, the value of the weight ω is highly subjective. This means that the edge weight coefficient of the power system line is easily interfered by the subjective weight factor, resulting in inaccurate calculation results. This uncertainty not only affects the rationality of the partition, but may also have a negative impact on the operation and management of the power system. Summary of the invention

[0005] The present application provides a method and system for calculating edge weight coefficients of an electric power system to solve the problem of inaccurate calculation results of edge weight coefficients.

[0006] In a first aspect, the present application provides a method for calculating edge weight coefficients of a power system, wherein the topological structure of the power system includes a power node, a load node, a transmission node and at least one line, the power node is connected to the load node through the line, and the transmission node is a node on the line; the method includes: Calculate a node impedance matrix of the topological structure to calculate a first power change and a second power change according to elements in the node impedance matrix; the first power change is a power change on one of the lines caused by a power change of a source-load node pair by a first magnitude, and the second power change is a power change on another of the lines caused by a power change of a source-load node pair by a first magnitude; the source-load node pair is a combination of any pair of power source nodes and load nodes; Acquire a correlation coefficient according to the first power change and the second power change, wherein the correlation coefficient is a relationship between power changes of one line and another line when the power of the source-load node pair changes; Calculate a third power change amount according to the correlation coefficient, wherein the third power change amount is a power change on all the lines caused when the power of any one of the lines changes by a second value; Linear weighted superposition is performed on the third power variation to obtain an edge weight coefficient.

[0007] Optionally, the first power variation is calculated by the following formula: ; Where s is the source node, t is the load node, st is the source-load node pair, ij is any line, i and j are the transmission nodes on line ij, is the first value, is the first power variation, is the element in the ith row and sth column of the node impedance matrix, is the element in the jth row and sth column of the node impedance matrix, is the element in the i-th row and t-th column of the node impedance matrix, is the element in the jth row and tth column of the node impedance matrix, is the reactance value of line ij.

[0008] Optionally, the second power variation is calculated by the following formula: ; Where mn is another line different from line ij, m and n are transmission nodes on line mn, is the second power variation, is the element in the mth row and sth column of the node impedance matrix, is the element in the nth row and sth column of the node impedance matrix, is the element in the mth row and tth column of the node impedance matrix, is the element in the nth row and tth column of the node impedance matrix, is the reactance value of line mn.

[0009] Optionally, acquiring a correlation coefficient according to the first power change amount and the second power change amount includes: Respectively acquiring a first correlation relationship between the first power variation and the first value and a second correlation relationship between the second power variation and the first value; The first value in the first association relationship and the second association relationship is eliminated to obtain the association coefficient.

[0010] Optionally, the correlation coefficient is calculated by the following formula: ; in, is the correlation coefficient between line ij and line mn.

[0011] Optionally, the third power variation is calculated by the following formula: ; in, is the third power variation caused by line x, x and y are the lines respectively, a is the number of lines, is the correlation coefficient between line x and line y.

[0012] Optionally, the edge weight coefficient is calculated by the following formula: ; in, is the edge weight coefficient, G is the set of the power nodes, L is the set of the load nodes, The active power injected into the power node, is the active power consumed by the load node, The smaller value is the active power injected into the source node and the active power consumed by the load node.

[0013] Optionally, the method further includes: The corresponding relationship between the edge weight coefficient and the line and the transmission node is obtained to construct an edge weight coefficient matrix according to the edge weight coefficient.

[0014] A second aspect of the present application provides a power system edge weight coefficient calculation system, which is applied to the method described in the first aspect, wherein the topological structure of the power system includes a power node, a load node, a transmission node and at least one line, the power node is connected to the load node through the line, and the transmission node is a node on the line; the system includes: A first calculation module: used for calculating the node impedance matrix of the topological structure, so as to calculate the first power change and the second power change according to the elements in the node impedance matrix; the first power change is the power change caused on one of the lines when the power of the source-load node pair changes by a first value, and the second power change is the power change caused on the other line when the power of the source-load node pair changes by a first value; the source-load node pair is a combination of any pair of power source nodes and load nodes; A second calculation module: used to obtain a correlation coefficient according to the first power change amount and the second power change amount, wherein the correlation coefficient is a relationship between the power change amounts of one line and another line when the power of the source-load node pair changes; A third calculation module: used for calculating a third power change according to the correlation coefficient, wherein the third power change is a power change on all the lines caused when the power of any one of the lines changes by a second value; The fourth calculation module is used to perform linear weighted superposition on the third power variation to obtain an edge weight coefficient.

[0015] The present application provides a method and system for calculating edge weight coefficients of an electric power system, the method comprising: calculating a node impedance matrix of a topological structure, and calculating a first power change and a second power change according to elements in the node impedance matrix, wherein the first and second power changes are respectively the power changes caused on different lines when the source-load node pair power changes by a first value; obtaining a correlation coefficient according to the first and second power changes, wherein the correlation coefficient is the relationship between the power changes between two different lines when the source-load node pair power changes; calculating a third power change according to the correlation coefficient, wherein the third power change is the power change caused on all lines when the power of any line changes by a second value; performing linear weighted superposition on the third power change to obtain an edge weight coefficient. When the power injected by a power source node or a load node of the electric power system changes, it is only necessary to update the node injection power to obtain a new line edge weight coefficient, without the need for repeated iterative flow calculations, and the efficiency of line edge weight coefficient calculations can also be improved. Since there is no need to use weights for calculation, the interference of subjective weight factors on the calculation of line edge weight coefficients can be reduced, making the calculation results more accurate, and thus the electric power system can be partitioned more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 An equivalent model diagram of the power system provided in the embodiment of the present application; Figure 2 A flow chart of a method for calculating edge weight coefficients of a power system provided in an embodiment of the present application; Figure 3 A schematic diagram of a 5-node power system network topology structure provided in an embodiment of the present application; Figure 4 A schematic diagram of the structure of a power system edge weight coefficient calculation system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] The following embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following embodiments do not represent all implementations consistent with the present application. They are only examples of systems and methods consistent with some aspects of the present application as detailed in the claims.

[0019] When using weighted indicators to define the line edge weight coefficient, the calculation of the edge weight coefficient is shown in the following formula: Line edge weight coefficient = ω × power system operating status index + (1-ω) edge betweenness index. This calculation method combines the power system operating status index and the edge betweenness index, and balances the influence of the two by adjusting the weight ω. Although this method can reflect the comprehensive characteristics of the line to a certain extent, the value of the weight ω is highly subjective. This means that the edge weight coefficient of the power system line is easily interfered by the subjective weight factor, resulting in inaccurate calculation results. This uncertainty not only affects the rationality of the partition, but may also have a negative impact on the operation and management of the power system.

[0020] In order to solve the problem of inaccurate edge weight coefficient calculation results, some embodiments of this application provide a method for calculating edge weight coefficients of a power system. Before describing the calculation method of this application, a brief description of the topological structure of the power system is given. The topological structure of the power system includes power nodes, load nodes, transmission nodes and at least one line. The power nodes are connected to the load nodes through the lines, and the transmission nodes are nodes on the lines. Figure 1 , Figure 1 is the equivalent model diagram of the power system, Figure 1 In the figure, s is the power node, t is the load node, i and j are the transmission nodes on any one line, and m and n are the transmission nodes on another line. The transmission nodes include the head node and the end node. It can be understood that the transmission node close to the power node s is the head node, then i and m are the head nodes on the line, and j and n are the end nodes on the line. The values ​​of s, t, i, j, m and n can be 1, 2, 3..., N.

[0021] See also Figure 2 , the calculation method provided in this application includes: S100: Calculate a node impedance matrix of a topological structure to calculate a first power variation and a second power variation according to elements in the node impedance matrix.

[0022] The node impedance matrix is ​​the inverse matrix of the node admittance matrix. The calculation process of the node impedance matrix can be obtained through existing technology and is not described in detail in this application. The first power change is the power change caused on one of the lines when the power of the source-load node pair changes by a first value. The second power change is the power change caused on another line when the power of the source-load node pair changes by a first value, where the source-load node pair is any combination of a power source node and a load node. According to the power transmission distribution factor of the DC power flow model, it is assumed that the power injected into the power node of the power system , power is drawn at load node t , then the power change caused on line ij is: ; (1) Where s is the source node, t is the load node, st is the source-load node pair, ij is any line, i and j are the transmission nodes on line ij, is the element in the ith row and sth column of the node impedance matrix, is the element in the jth row and sth column of the node impedance matrix, is the element in the i-th row and t-th column of the node impedance matrix, is the element in the jth row and tth column of the node impedance matrix, is the reactance value of line ij. It can be understood that in the above formula (1), is the first value, That is the first power variation.

[0023] Similarly, according to formula (1), the power change caused on line ij when the power of source-load node pair st changes by a first value, i.e., the second power change, can be calculated by the following formula: ; (2) Where mn is another line different from line ij, m and n are transmission nodes on line mn, is the second power variation, is the element in the mth row and sth column of the node impedance matrix, is the element in the nth row and sth column of the node impedance matrix, is the element in the mth row and tth column of the node impedance matrix, is the element in the nth row and tth column of the node impedance matrix, is the reactance value of line mn.

[0024] S200: Obtain a correlation coefficient according to the first power change amount and the second power change amount.

[0025] In some embodiments, obtaining a correlation coefficient based on a first power change and a second power change includes: obtaining a first correlation relationship between the first power change and a first value and a second correlation relationship between the second power change and the first value, respectively; eliminating the first value in the first correlation relationship and the second correlation relationship to obtain a correlation coefficient. The correlation coefficient is the relationship between the power change of one line and another line when the power of the source-load node changes. It can be understood that the above formula (1) is the first correlation relationship, and formula (2) is the second correlation relationship.

[0026] The above formulas (1) and (2) respectively describe the relationship between the power changes of the two lines and the source-load node pair st in the power system, where and They respectively reflect the contribution of line ij and line mn to the power variation of st at the source-load node. and There are two problems with the edge weight coefficient of the line. On the one hand, the edge weight coefficient can not fully reflect the characteristics of the line by only calculating the edge weight coefficient through a pair of source-load node pairs st. On the other hand, the source-load node pairs st have no corresponding network topology expression in the power system. and It is not possible to correspond to the topological structure, which is not conducive to establishing a complete power system network topological structure model. Therefore, in the embodiment of the present application, formulas (1) and (2) are combined to eliminate the first value , we can get the relationship between the power changes of the two lines ij and mn, which can not only reflect the impact of line ij on the power change of the power system, but also correspond to the topological relationship of the lines. Combining formulas (1) and (2), we can eliminate the first value Then we can get the following formula: ; (3) but That is the correlation coefficient between line ij and line mn, let: ; (4) Combining formula (3) and formula (4), we have: ; (5) in, is the correlation coefficient between line ij and line mn. The above formula (5) describes the relationship between the power changes of any two lines ij and line mn under the influence of the source-load node pair st.

[0027] S300: Calculate a third power variation according to the correlation coefficient.

[0028] The third power change is the power change on all lines caused by the second value of the power change of any line. In some embodiments, the second value may be unit power. If it is necessary to establish a relationship between the power change of line ij and all lines in the power system, it is necessary to accumulate the power changes of each line. Define the line with the first end node i and the end node j as line x, and the line with the first end node m and the end node n as line y, where the values ​​of x and y can be 1, 2, 3..., a. According to formula (5), we have: ; (6) in, is the first power variation of line x, is the correlation coefficient between line x and line y, is the second power variation of line y.

[0029] definition When only the source-load node pair st is affected, the power change of each line in the entire network caused by the unit power change of line x, that is, the second value, is the third power change. The third power change can be calculated by the following formula: ; (7) in, is the third power change caused by line x, x and y are the lines respectively, a is the number of lines, when x=y, .

[0030] S400: Performing linear weighted superposition on the third power variation to obtain an edge weight coefficient.

[0031] It is understandable that since there are no unique source-load node pairs in the power system, the impact of all source-load node pairs on the line should be added together to fully reflect the impact of the line on the power change of the power system. The impact of all source-load node pairs including the source-load node pair st is linearly weighted superimposed, where the weight is the smaller value of the power in the power source node s and the load node t, and the calculation formula of the edge weight coefficient can be obtained as follows: ; (8) in, is the edge weight coefficient, G is the set of power nodes, L is the set of load nodes, The active power injected into the power node, is the active power consumed by the load node, The smaller value is the active power injected into the source node and the active power consumed by the load node. It reflects the impact of all source-load node pairs on the power changes of all lines in the entire network when the power of line x changes. Therefore, it can be used as the weight coefficient to characterize the importance of line x, that is, the edge weight coefficient of the line.

[0032] The calculation method provided in the present application uses the power change as the calculation parameter of the line edge weight coefficient to establish a weighted network model of the power system. When the power injected into the power source node or load node of the power system changes, it is only necessary to update the node injection power to obtain a new line edge weight coefficient, thereby updating the weighted network model of the power system. The line edge weight coefficient calculated by the above method can be updated according to the power change of the power system node. Since there is no need to use weights for calculation and it is not affected by subjective factors, it can not only reflect the actual operation status of the power system, but also improve the accuracy of the calculation results, thereby partitioning the power system more accurately. And since the above calculation process does not need to rely on the power system flow calculation results and perform repeated iterative flow calculations, it can also improve the efficiency of the line edge weight coefficient calculation.

[0033] In order to establish a complete weighted network model of the power system, the transmission nodes, lines and edge weight coefficients of the lines in the power system are matched one by one. Construct edge weight coefficient matrix (The edge weight coefficient matrix of the M-node power system is an M-order square matrix), so in some embodiments, the method further includes: obtaining the corresponding relationship between the edge weight coefficient and the line and the transmission node to construct an edge weight coefficient matrix according to the edge weight coefficient. The element in row i and column j It can be expressed as: ; (9) The influence of the power change of the line with the first node i and the last node j on the power change of all lines in the whole network is obviously , edge weight coefficient matrix is a symmetric matrix. Edge weight coefficient matrix It not only includes the edge weight coefficients of each line, but also reflects the association relationship between different transmission nodes (when there is a line connecting the head node i and the terminal node j, It is not zero, otherwise it is zero), and it also includes the structural characteristics and operating status characteristics of the power system.

[0034] See also Figure 3 , l1-l6 are transmission lines, p1-p5 are transmission nodes, G1-G4 are power supply nodes, and Figure 3 Taking the power system in as an example, the calculation method of the present application is used to calculate the edge weight coefficient of the line. The parameters of the power system are shown in Tables 1 and 2, and the calculated edge weight coefficients of each line are shown in Table 3.

[0035] Table 1: Parameters of 5-node power system line

[0036] Table 2: Parameters of transmission nodes in a 5-node power system

[0037] Table 3: Line edge weight coefficients of 5-node power system

[0038] Change the active power injected into the power node G2 The power of the transmission node p3 can be changed so that the active power injected by the power node G2 is =100MW, other parameters remain unchanged, and the calculated line edge weight coefficients are shown in Table 4. In Tables 3 and 4, the results of electrical betweenness and power flow betweenness are calculated using the weight ω.

[0039] Table 4: Line edge weight coefficients of the 5-node power system after changing the injection power of the transmission node p3

[0040] Compare the line edge weight coefficients and electrical betweenness and power flow betweenness in Tables 3 and 4. It can be seen from the data in Tables 3 and 4 that in the traditional calculation of edge weight coefficients, since the value of the weight ω is highly subjective, it has a significant impact on the line edge weight coefficient, resulting in the line edge weight coefficient obtained by weighted calculation of power flow betweenness and electrical betweenness being inaccurate. Moreover, the electrical betweenness will not change when the power injected into the power supply node of the power system changes, and cannot reflect the actual operation of the power system. Although the power flow betweenness can reflect the impact of changes in the power injected into the power system on the line edge weight coefficient, the calculation process involves iterative power flow calculation, and the calculation cycle is significantly longer than the edge weight coefficient calculation method in this application, for example Figure 3 The calculation time of the edge weight coefficient of the power system is shown to be 0.0313s, and the calculation time of the power flow intermediate number is 1.42s. The calculation method provided in this application can update the edge weight coefficient of the line in the power system when the power injected into the power node of the power system changes, which can reflect the actual operation of the power system and the calculation result is more accurate.

[0041] Based on the above method, some embodiments of the present application also provide a power system edge weight coefficient calculation system, which is applied to the method provided in the above embodiment, wherein the topological structure of the power system includes a power node, a load node, a transmission node and at least one line, the power node is connected to the load node through the line, and the transmission node is a node on the line. Figure 4 , the system includes: The first calculation module is used to calculate the node impedance matrix of the topological structure, so as to calculate the first power variation and the second power variation according to the elements in the node impedance matrix.

[0042] Among them, the first power change is the power change on one of the lines caused by the power change of the source-load node pair by a first value, and the second power change is the power change on another line caused by the power change of the source-load node pair by the first value; the source-load node pair is any combination of a power source node and a load node.

[0043] The second calculation module is used to obtain a correlation coefficient according to the first power change amount and the second power change amount.

[0044] The correlation coefficient is the relationship between the power change of one line and another line when the power of the source-load node changes.

[0045] The third calculation module is used to calculate the third power change according to the correlation coefficient.

[0046] The third power change is the power change on all lines caused when the power of any line changes by the second value.

[0047] The fourth calculation module is used to perform linear weighted superposition on the third power variation to obtain an edge weight coefficient.

[0048] It can be seen from the above technical scheme that the embodiment of the present application provides a method and system for calculating the edge weight coefficient of an electric power system, and the method includes: calculating the node impedance matrix of the topological structure to calculate the first power change and the second power change according to the elements in the node impedance matrix, wherein the first and second power changes are the power changes caused on different lines when the source load node changes the power by the first value; obtaining the correlation coefficient according to the first and second power changes, wherein the correlation coefficient is the relationship between the power changes between two different lines when the source load node changes the power; calculating the third power change according to the correlation coefficient, wherein the third power change is the power change caused on all lines when the power of any line changes by the second value; performing linear weighted superposition on the third power change to obtain the edge weight coefficient. When the power injected by the power source node or the load node of the electric power system changes, it is only necessary to update the node injection power to obtain a new line edge weight coefficient, without the need for repeated iterative flow calculation, and the efficiency of line edge weight coefficient calculation can also be improved. Since there is no need to use weights for calculation, the interference of subjective weight factors on the calculation of line edge weight coefficients can be reduced, making the calculation results more accurate, and thus the electric power system can be partitioned more accurately.

[0049] Similar parts between the embodiments provided in this application can be referenced to each other. The specific implementation methods provided above are only a few examples under the general concept of this application and do not constitute a limitation on the protection scope of this application. For those skilled in the art, any other implementation methods expanded based on the scheme of this application without creative work belong to the protection scope of this application.

Claims

1. A method for calculating edge weight coefficients of a power system, characterized in that: The topological structure of the power system includes a power source node, a load node, a transmission node and at least one line, the power source node is connected to the load node through the line, and the transmission node is a node on the line; the method includes: Calculate a node impedance matrix of the topological structure to calculate a first power change and a second power change according to elements in the node impedance matrix; the first power change is a power change on one of the lines caused by a power change of a source-load node pair by a first magnitude, and the second power change is a power change on another of the lines caused by a power change of a source-load node pair by a first magnitude; the source-load node pair is a combination of any pair of power source nodes and load nodes; Acquire a correlation coefficient according to the first power change and the second power change, wherein the correlation coefficient is a relationship between power changes of one line and another line when the power of the source-load node pair changes; Calculate a third power change amount according to the correlation coefficient, wherein the third power change amount is a power change on all the lines caused when the power of any one of the lines changes by a second value; Linear weighted superposition is performed on the third power variation to obtain an edge weight coefficient.

2. The method for calculating edge weight coefficients of a power system according to claim 1, characterized in that: The first power variation is calculated by the following formula: ； Where s is the source node, t is the load node, st is the source-load node pair, ij is any line, i and j are the transmission nodes on line ij, is the first value, is the first power variation, is the element in the ith row and sth column of the node impedance matrix, is the element in the jth row and sth column of the node impedance matrix, is the element in the i-th row and t-th column of the node impedance matrix, is the element in the jth row and tth column of the node impedance matrix, is the reactance value of line ij.

3. The method for calculating edge weight coefficients of a power system according to claim 2, characterized in that: The second power variation is calculated by the following formula: ； Where mn is another line different from line ij, m and n are transmission nodes on line mn, is the second power variation, is the element in the mth row and sth column of the node impedance matrix, is the element in the nth row and sth column of the node impedance matrix, is the element in the mth row and tth column of the node impedance matrix, is the element in the nth row and tth column of the node impedance matrix, is the reactance value of line mn.

4. The method for calculating edge weight coefficients of a power system according to claim 3, characterized in that: The acquiring of the correlation coefficient according to the first power change amount and the second power change amount comprises: Respectively acquiring a first correlation relationship between the first power variation and the first value and a second correlation relationship between the second power variation and the first value; The first value in the first association relationship and the second association relationship is eliminated to obtain the association coefficient.

5. The method for calculating edge weight coefficients of a power system according to claim 3, characterized in that: The correlation coefficient is calculated by the following formula: ； in, is the correlation coefficient between line ij and line mn.

6. The method for calculating edge weight coefficients of a power system according to claim 5, characterized in that: The third power variation is calculated by the following formula: ； in, is the third power variation caused by line x, x and y are the lines respectively, a is the number of lines, is the correlation coefficient between line x and line y.

7. The method for calculating edge weight coefficients of a power system according to claim 6, characterized in that: The edge weight coefficient is calculated by the following formula: ； in, is the edge weight coefficient, G is the set of the power nodes, L is the set of the load nodes, The active power injected into the power node, is the active power consumed by the load node, The smaller value is the active power injected into the source node and the active power consumed by the load node.

8. The method for calculating edge weight coefficients of a power system according to claim 1, characterized in that: The method further comprises: The corresponding relationship between the edge weight coefficient and the line and the transmission node is obtained to construct an edge weight coefficient matrix according to the edge weight coefficient.

9. A power system edge weight coefficient calculation system, characterized in that: The method applied to any one of claims 1 to 8, wherein the topological structure of the power system includes a power node, a load node, a transmission node and at least one line, the power node is connected to the load node through the line, and the transmission node is a node on the line; the system includes: A first calculation module: used for calculating the node impedance matrix of the topological structure, so as to calculate the first power change and the second power change according to the elements in the node impedance matrix; the first power change is the power change caused on one of the lines when the power of the source-load node pair changes by a first value, and the second power change is the power change caused on the other line when the power of the source-load node pair changes by a first value; the source-load node pair is a combination of any pair of power source nodes and load nodes; A second calculation module: used to obtain a correlation coefficient according to the first power change amount and the second power change amount, wherein the correlation coefficient is a relationship between the power change amounts of one line and another line when the power of the source-load node pair changes; A third calculation module: used for calculating a third power change according to the correlation coefficient, wherein the third power change is a power change on all the lines caused when the power of any one of the lines changes by a second value; The fourth calculation module is used to perform linear weighted superposition on the third power variation to obtain an edge weight coefficient.

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