CN103529275A - Short-circuit current analysis method and device of regional power grid - Google Patents

Abstract

The invention provides a method and device for analyzing the short-circuit current of a regional power grid, including: dividing the power grid system into regions: dividing the regions that need to analyze and calculate the short-circuit current level into research regions, and dividing the regions directly connected with the research region into boundaries Area, divide the area except the research area and the boundary area into the external area; perform equivalent simplification on the boundary area and the external area to form the equivalent boundary area, and obtain the research area and the equivalent boundary area. The grid system after equivalent value; according to the grid system after equivalent value, analyze and calculate the short-circuit current level of the research area. The invention solves the technical problem in the prior art that it is difficult to reduce the amount of data in short-circuit current analysis while ensuring the calculation accuracy of short-circuit current, and achieves the reduction of data amount in short-circuit current analysis on the basis of ensuring the calculation accuracy of short-circuit current and the technical effect of the amount of computation.

Description

Method and device for analyzing short-circuit current of regional power grid

technical field

The invention relates to the technical field of electric power systems, in particular to a method and device for analyzing the short-circuit current of a regional power grid.

Background technique

Short-circuit current calculation is an indispensable basic calculation in the design and operation of power systems. The results of short-circuit current calculation are generally used in the selection of electrical equipment and current-carrying conductors, the determination of relay protection devices, the main wiring scheme and operation determination of the method, etc. In addition, the short-circuit current calculation must also be carried out in the transient stability analysis of the power system and the determination of the interference of the transmission line on the communication.

In recent years, with the continuous expansion of the scale of the power system, the connection between the power grids has gradually strengthened. Due to the strengthening of the grid structure, the electrical distance has been shortened, and the short-circuit current of some plants has increased significantly, even exceeding the breaking capacity of the switch. The problem of short-circuit current has attracted more and more attention from the power planning, dispatching and operation departments.

At present, when calculating the short-circuit current of a power grid, we often only pay attention to the short-circuit current level of the area where the power grid is located (which can be called the research area). In order to ensure the accuracy of calculating the short-circuit current in the area, it is necessary to calculate and analyze the areas in the power system other than the research area. If the data of the entire power network is analyzed and calculated, the calculation speed will be very slow, and at the same time, it is necessary to maintain the power grid data of other regions except the research area, which will greatly increase the amount of data and the amount of short-circuit current analysis. Calculations.

At the same time, with the continuous expansion of the scale of the power grid, in order to ensure the accuracy of short-circuit current calculations, the amount of data required by power grid operators to analyze and calculate short-circuit currents is becoming larger and larger, and the amount of data for data analysis is also increasing. This will inevitably lead to higher and higher requirements for simulation software and computer configuration. At the same time, some commercial software also has certain requirements on the scale of the power grid due to the limitation of the algorithm of the program itself.

How to reduce the amount of data in short-circuit current analysis while ensuring the calculation accuracy of short-circuit current has not yet proposed an effective solution.

Contents of the invention

The invention provides a method and device for analyzing short-circuit current of a regional power grid to at least solve the technical problem in the prior art that it is difficult to reduce the amount of data in short-circuit current analysis while ensuring the accuracy of short-circuit current calculation.

An embodiment of the present invention provides a method for analyzing the short-circuit current of a regional power grid, which includes: dividing the power grid system into regions: dividing the regions that need to analyze and calculate the short-circuit current level into research regions, and dividing the regions directly connected with the research regions into boundaries Area, divide the area except the research area and the boundary area into the external area; perform equivalent simplification on the boundary area and the external area to form the equivalent boundary area, and obtain the research area and the equivalent boundary area. The grid system after equivalent value; according to the grid system after equivalent value, analyze and calculate the short-circuit current level of the research area.

In one embodiment, the boundary area and the external area are equivalently simplified to form an equivalent boundary area, and an equivalent power grid system composed of the research area and the equivalent boundary area is obtained, including: according to the external Construct the node admittance matrix of the power grid system in the order of region, boundary region and research region; use the Gaussian elimination method to eliminate the part of the outer region in the node admittance matrix, and form an equivalent post-node admittance matrix that only retains the boundary region and the research region ;Determine the variation matrix of the matrix elements corresponding to the boundary area in the node admittance matrix after the equivalence; determine the increased generator, the increased connection branch, and the increased power generation in the boundary area after the equivalent value is determined according to the variation matrix The reactance parameter of the generator and the reactance parameter of the added connection branch; the network reconstruction is carried out according to the determined added generator, the added connection branch, the added reactance parameter of the generator, and the added reactance parameter of the connected branch Form the equivalent grid system.

In one embodiment, determining the reactance parameter of the added connection branch in the boundary area after equivalence according to the change matrix includes: determining the node numbers at both ends of the added connection branch; The negative reciprocal of the element corresponding to the node number is used as the reactance parameter of the added connecting branch.

In one embodiment, determining the reactance parameter of the added generator in the boundary area after equivalence according to the variation matrix includes: determining the node number of the node connected to the added generator; The total admittance is obtained by adding the admittance of the connecting branch directly connected to the node number and the elements on the row where the node number is located in the variation matrix; the reciprocal of the total admittance is taken as the reactance parameter of the added generator.

In one embodiment, determining the variation matrix of the matrix elements corresponding to the boundary area in the equivalent node admittance matrix includes: determining the number of nodes in the boundary area; when the number of nodes in the boundary area is less than a predetermined threshold Next, the method of solving linear equations is used to calculate the variation matrix.

In one embodiment, the predetermined threshold is 6.

The embodiment of the present invention also provides a regional power grid short-circuit current analysis device, including: a region division module, which is used to divide the power grid system into regions: divide the regions that need to analyze and calculate the short-circuit current level into research regions, and divide the regions that are related to the research region The directly connected areas are divided into boundary areas, and the areas other than the research area and the boundary area are divided into external areas; the equivalent simplification module is used to perform equivalent simplification of the boundary area and the external area to form an equivalent boundary area , to obtain the equivalent power grid system composed of the research area and the equivalent boundary area; the analysis module is used to analyze and calculate the short-circuit current level of the research area according to the equivalent power grid system.

In one embodiment, the equivalent simplification module includes: a construction unit for constructing the node admittance matrix of the power grid system in the order of the external area, the boundary area and the research area; a simplification unit for eliminating The part of the outer area in the nodal admittance matrix forms the post-equivalent nodal admittance matrix that only retains the boundary area and the research area; the matrix determination unit is used to determine the change of the matrix elements corresponding to the boundary area in the post-equivalent nodal admittance matrix Quantity matrix; parameter determination unit, used to determine the added generator, the increased connection branch in the boundary area after the equivalence according to the variation matrix, and the reactance parameter of the increased generator and the reactance of the increased connection branch Parameters; a reconstruction unit, configured to perform network reconfiguration according to the added generator, the added connection branch, the added reactance parameter of the generator, and the added reactance parameter of the connected branch to form an equivalent grid system.

In one embodiment, the parameter determination unit includes: a first node number determination subunit, used to determine the node numbers at both ends of the added connection branch; a first parameter determination subunit, used to obtain the difference between the two The negative reciprocal of the element corresponding to the node number of the end is used as the reactance parameter of the added connection branch.

In one embodiment, the parameter determination unit includes: a second node number determination subunit, used to determine the node number of the node connected to the added generator; The admittance of the connecting branch directly connected to the node and each element on the row of the node number in the variation matrix are summed to obtain the total admittance; the second parameter determines the subunit, which is used to take the reciprocal of the total admittance as the increase The reactance parameters of the generator.

In one embodiment, the matrix determination unit includes: a node number determination subunit, configured to determine the number of nodes in the boundary area; a calculation subunit, used for when the number of nodes in the boundary area is less than a predetermined threshold , using the linear equation solution method to calculate the variation matrix.

In one embodiment, the predetermined threshold is 6.

In the embodiment of the present invention, the areas in the grid system that need to analyze and calculate the short-circuit current level are divided into research areas, and then the areas that have direct contact with the research area are divided into boundary areas, and the areas other than the research area and the boundary area are divided into Divide it into external areas, and then simplify the grid system equivalently to a grid system that only includes the research area and the equivalent boundary area, and finally calculate the short-circuit current level of the research area through the analysis of the equivalent grid system, because the equivalent simplification In the future grid system there is no longer any external area, so the amount of data required for analysis and calculation of short-circuit current levels will be significantly reduced. The above method effectively solves the technical problem in the prior art that it is difficult to reduce the amount of data in short-circuit current analysis while ensuring the calculation accuracy of short-circuit current, and achieves the reduction of short-circuit current analysis on the basis of ensuring the calculation accuracy of short-circuit current Technical effects of data volume and computation volume.

Description of drawings

The drawings described here are used to provide further understanding of the present invention, constitute a part of the application, and do not limit the present invention. In the attached picture:

Fig. 1 is the flowchart of the method for analyzing the short-circuit current of the regional power grid in an embodiment of the present invention;

Fig. 2 is a flowchart of network equivalent simplification according to an embodiment of the present invention;

Fig. 3 is the flow chart of the specific embodiment of the method for analyzing the short-circuit current of the regional power grid in the embodiment of the present invention;

FIG. 4 is a schematic diagram of network structure area division according to an embodiment of the present invention;

Fig. 5 is a schematic diagram of the line admittance of the connecting line between the various regions according to the embodiment of the present invention;

Fig. 6 is a network wiring diagram of a certain node in the boundary area after equivalent simplification according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of network structure division of IEEE39 nodes according to an embodiment of the present invention;

Fig. 8 is a structural block diagram of a regional power grid short-circuit current analysis device according to an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the embodiments and accompanying drawings. Here, the exemplary embodiments and descriptions of the present invention are used to explain the present invention, but not to limit the present invention.

In an embodiment of the present invention, a short-circuit current analysis of a regional power grid is provided. As shown in FIG. 1, the method includes the following steps:

Step 101: Divide the power grid system into regions: divide the regions that need to analyze and calculate the short-circuit current level into the research regions, divide the regions that have direct contact with the research regions into the boundary regions, and divide the regions other than the research region and the boundary region into outside area;

Step 102: Perform equivalent simplification of the boundary area and the external area to form an equivalent boundary area, and obtain an equivalent power grid system composed of the research area and the equivalent boundary area;

Step 103: Analyze and calculate the short-circuit current level in the research area according to the equivalent grid system.

In the above-mentioned embodiments, the areas in the power grid system that need to analyze and calculate the short-circuit current level are divided into research areas, and then the areas that have direct contact with the research area are divided into boundary areas, and the areas other than the research area and the boundary area are divided into is the external area, and then the grid system equivalent is simplified to a grid system that only includes the research area and the equivalent boundary area, and finally the short-circuit current level of the research area is calculated through the analysis of the equivalent grid system, because after the equivalent simplification There are no longer external areas in the network system of , so the amount of data required for the analysis and calculation of short-circuit current levels will be significantly reduced. The above method effectively solves the technical problem in the prior art that it is difficult to reduce the amount of data in short-circuit current analysis while ensuring the calculation accuracy of short-circuit current, and achieves the reduction of short-circuit current analysis on the basis of ensuring the calculation accuracy of short-circuit current Technical effects of data volume and computation volume.

In one embodiment, the equivalent simplification of the power grid system can be performed through the node admittance matrix of the power grid system. In one embodiment, the above step 102 performs equivalent simplification of the boundary area and the outer area to form an equivalent boundary area, to obtain the equivalent grid system composed of the research area and the equivalent boundary area, as shown in Figure 2, including the following steps:

Step 201: Construct the node admittance matrix of the power grid system in the order of the external area, the boundary area and the research area;

Step 202: using the Gaussian elimination method to eliminate the part of the outer region in the node admittance matrix to form an equivalent post-node admittance matrix that only retains the boundary region and the research region;

Step 203: Determine the variation matrix of the matrix elements corresponding to the boundary area in the equivalent node admittance matrix;

Step 204: Determine the added generator, the added connection branch, and the added reactance parameter of the generator and the added reactance parameter of the connected branch in the boundary area after equivalence according to the variation matrix;

Step 205: Perform network reconfiguration according to the determined added generator, the added connection branch, the reactance parameter of the added generator, the reactance parameter of the added connection branch, and the connection mode between the generator and the connection branch. Construct the grid system after equivalence.

That is, first construct the node admittance matrix of the power grid system, and then eliminate the matrix elements corresponding to the outer regions in the node admittance matrix through the Gaussian elimination method. After Gaussian elimination, the matrix elements corresponding to the outer regions will be equivalent to the boundary Among the matrix elements corresponding to the region, it can be found that only the matrix elements corresponding to the boundary region in the equivalent simplified node admittance matrix have changed, and the equivalent grid structure can be determined directly according to the change of the matrix elements corresponding to the boundary region Added generators and connecting branches in the boundary region, and added reactance parameters for generators and connecting branches. When performing equivalent simplification and reconstructing the power grid system, the original nodes and connecting branches in the boundary area can be kept unchanged, but the new generators and connecting branches can be added to the corresponding positions in the boundary area.

Specifically, determining the added reactance parameters of the generator and the added reactance parameters of the connecting branch in the boundary area after the equivalence according to the variation matrix may include:

1) Determine the node numbers at both ends of the added connection branch; take the negative reciprocal of the elements corresponding to the node numbers at both ends in the variation matrix as the reactance parameter of the added connection branch;

2) Determine the node number of the node connected to the added generator; compare the admittance of the connecting branch directly connected to the node of the node number in the external area, and each element on the row of the node number in the variation matrix The total admittance is obtained by adding operation; the reciprocal of the total admittance is taken as the reactance parameter of the added generator.

In order to specifically illustrate the principles of the above-mentioned steps 201 to 205, the method for analyzing the short-circuit current of the regional power grid provided by the embodiment of the present invention will be specifically described below in conjunction with a specific example.

In this embodiment, the method for analyzing the short-circuit current of the regional power grid is shown in Figure 3, and includes the following steps:

Step 301: Region division

Specifically, select the area that needs to analyze and calculate the short-circuit current level as the research area, the area that is directly connected with the research area as the boundary area, and the area other than the research area and the boundary area as the external area. After the network is divided, the research area and the border area are connected through the tie line, the border area is connected with the outer area through the tie line, and there is no direct connection between the research area and the outer area.

Step 302: Network Simplification

Specifically, the system-wide node admittance matrix Y is constructed in the order of the external area, the boundary area, and the research area. For example: Gaussian elimination method can be used for equivalent simplification of the network to eliminate the part of the outer area in Y, and form a node admittance matrix that only retains the equivalent value of the boundary area and the research area

Step 303: Border area network reconstruction

Using the contact line parameters between the study area and the boundary area and the equivalent post-nodal admittance matrix generated in the above step 302 Part of the elements in , to reconstruct the border area network. Among them, the above-mentioned boundary network reconfiguration includes: tie line reconfiguration and generator reconfiguration, and at the same time, it is also necessary to calculate the reactance parameters of newly added components (including new generators and new connection branches) in the reconfigured network.

Step 304: Perform short-circuit current analysis according to the reconstructed network.

The above step 302 and step 303 are described in detail below:

In the above-mentioned step 302 of network simplification, when analyzing and calculating the power grid, in order to reduce the computer memory and reduce the workload of personnel, the part of the network that does not need to be analyzed can be simplified by equivalent value. As shown in Figure 4, it is a schematic diagram of the area division of the network structure. Taking the system shown in Figure 4 as an example, the node set in the research area is represented by A, the node set in the border area is represented by B, and the node set in the external area is represented by C .

According to the order of the external area, the boundary area and the research area, the nodal admittance matrix Y of the whole system is formed. According to the characteristics of the reciprocal inversion of the nodal admittance matrix and the nodal impedance matrix, the block matrix form Equation 1 is shown as follows:

$\left[\begin{array}{ccc}{Y}_{\mathrm{CC}}& Y_{\mathrm{CB}}& 0\\ Y_{\mathrm{BC}}& Y_{\mathrm{BB}}& Y_{\mathrm{BA}}\\ 0& Y_{\mathrm{AB}}& Y_{\mathrm{AAA}}\end{array}\right]*\left[\begin{array}{ccc}{Z}_{\mathrm{CC}}& Z_{\mathrm{CB}}& Z_{\mathrm{CA}}\\ Z_{\mathrm{BC}}& Z_{\mathrm{BB}}& Z_{\mathrm{BA}}\\ Z_{\mathrm{AC}}& Z_{\mathrm{AB}}& Z_{\mathrm{AAA}}\end{array}\right]=\left[\begin{array}{ccc}{\mathrm{E.}}_{\mathrm{CC}}& 0& 0\\ 0& {\mathrm{E.}}_{\mathrm{BB}}& 0\\ 0& 0& {\mathrm{E.}}_{\mathrm{AAA}}\end{array}\right]$ (Formula 1)

Among them, Y represents the node admittance matrix, Z represents the node impedance matrix, and E represents the identity matrix.

At present, the electric power industry mainly adopts the equivalent voltage source method when calculating the short-circuit current, that is, the short-circuit current value is calculated by solving the short-circuit impedance of the fault point. According to the nature of the node impedance matrix, the element Z _kk on its diagonal is the total impedance to ground seen from node k to the entire network, also known as self-impedance or input impedance, and Z _kk is a short circuit when a metallic short circuit occurs in the power grid impedance.

When calculating the short-circuit current of the regional power grid, we only need to care about the short-circuit current level of each station in the research area, that is, only need to calculate the elements on the diagonal in the block matrix Z _AA , so the corresponding calculation formula is as follows: 2.

$\left[\begin{array}{ccc}{Y}_{\mathrm{CC}}& Y_{\mathrm{CB}}& 0\\ Y_{\mathrm{BC}}& Y_{\mathrm{BB}}& Y_{\mathrm{BA}}\\ 0& Y_{\mathrm{AB}}& Y_{\mathrm{AAA}}\end{array}\right]*\left[\begin{array}{c}{Z}_{\mathrm{CA}}\\ Z_{\mathrm{BA}}\\ Z_{\mathrm{AAA}}\end{array}\right]=\left[\begin{array}{c}0\\ 0\\ {\mathrm{E.}}_{\mathrm{AAA}}\end{array}\right]$ (Formula 2)

Using the Gaussian elimination method to eliminate the outer area C, we can get:

$\left[\begin{array}{cc}{\tilde{Y}}_{\mathrm{BB}}& Y_{\mathrm{BA}}\\ Y_{\mathrm{AB}}& Y_{\mathrm{AAA}}\end{array}\right]*\left[\begin{array}{c}{Z}_{\mathrm{BA}}\\ Z_{\mathrm{AAA}}\end{array}\right]=\left[\begin{array}{c}0\\ {\mathrm{E.}}_{\mathrm{AAA}}\end{array}\right]$ (Formula 3)

Comparing the above formula 2 and the above formula 3, it can be seen that only the matrix elements corresponding to the boundary area in the equation after the equivalence have changed, that is, only Y _BB has changed, and the amount of change of Y _BB before and after the equivalence is:

${\mathrm{\ΔY}}_{\mathrm{BB}}={\tilde{Y}}_{\mathrm{BB}}-Y_{\mathrm{BB}}=-Y_{\mathrm{BC}}{Y}_{\mathrm{CC}}^{-1}{Y}_{\mathrm{CB}}$ (Formula 4)

From the above derivation, the change ΔY _BB of Y _BB before and after equivalent simplification represents the impact of external nodes on internal nodes. According to the nature of matrix transposition, ΔY _BB and Y _BB are symmetrical matrices, so the boundary area can be reconstructed as An electrical network with new branches added.

In the process of network reconstruction of the boundary area in the above step 303, according to the change of the node admittance matrix in the equivalence process deduced above, since the input data of the short-circuit current calculation software is the model parameters of the power system components, it is necessary to The matrix form after the value is converted into the actual grid connection structure, that is, the network reconfiguration problem. The network reconfiguration in the short-circuit current calculation process includes tie line reconfiguration and generator reconfiguration, and the reactance parameters of the newly added components also need to be calculated.

Taking the system shown in FIG. 4 above as an example, a specific implementation method of border area network reconfiguration in the equivalence process will be described in detail. The three nodes in the boundary area are named b1, b2, and b3 respectively, and the line admittance of the connecting line between each area is shown in Figure 5.

Taking node b1 in the boundary area as an example, this paper introduces the methods of tie line reconstruction and generator reconstruction in the boundary area network reconstruction after network equivalence. The solution process includes the following steps:

S1: Before equivalence, the self-admittance of node b1 in Y _BB is:

Y _BB (b1,b1)=y1+y4+y5+y6 (Equation 5)

The mutual admittance of node b1 is:

$\left\{\begin{array}{c}{Y}_{\mathrm{BB}}(b1,b2)=-\mathrm{the\; y}4\\ Y_{\mathrm{BB}}(b1,b3)=0\end{array}\right.$ (Formula 6)

S2: After equivalence, it can be known from formula 4 that there is a new element on the row element where b1 node is located in matrix Y _BB , assuming that the element in the row where b1 is located in ΔY _BB calculated by formula 4 is:

ΔY _BB (b1)=[Δy1 Δy2 Δy3] (Equation 7)

中b1节点所在的行元素为：From formulas 5 to 7, it can be concluded that the equivalent matrix

The row element where the b1 node is located is:

$\left\{\begin{array}{c}{\tilde{Y}}_{\mathrm{BB}}(b1,b1)=Y_{\mathrm{BB}}(b1,b1)+{\mathrm{\ΔY}}_{\mathrm{BB}}(b1,b1)\\ =\mathrm{the\; y}1+\mathrm{the\; y}4+\mathrm{the\; y}5+\mathrm{the\; y}6+\mathrm{\Δy}1\\ {\tilde{Y}}_{\mathrm{BB}}(b1,b2)=-\mathrm{the\; y}4+\mathrm{\Δy}2\\ {\tilde{Y}}_{\mathrm{BB}}(b1,b3)=\mathrm{\Δy}3\end{array}\right.$ (Formula 8)

According to the requirements of network simplification and ΔY _BB , The characteristics of the network connection of node b1 after equivalent simplification as shown in Figure 6 can be obtained. From the mutual admittance part in formula 8, it can be seen that the newly added admittance between node b1 and node b2 is -Δy2 The new line between node b1 and node b3 with an admittance of -Δy3 can be seen from the self-admittance part of formula 8. After the equivalence, there is a new branch to the ground at node b1, and the short circuit in the calculation of short circuit current From the concept of impedance, it can be seen that the ground branch can be equivalent to the generator branch, and the subtransient reactance of the new generator is X′′ _d (converted into admittance is y′′).

It can be seen from Fig. 6 that for node b1, the newly added line parameters for nodes b2 and b3 can be determined through the mutual admittance part in formula 7, but for the equivalent generator reactance parameters cannot be directly obtained, as shown in Fig. 6 The network structure in can be concluded that the self-admittance of b1 node after equivalence is:

${\tilde{Y}}_{\mathrm{BB}}(b1,b1)=\mathrm{the\; y}1+\mathrm{the\; y}4-\mathrm{\Δy}2-\mathrm{\Δy}3+{\mathrm{the\; y}}^{\′\′}$ (Formula 9)

表达式，可得：Compare Equation 8 and Equation 9 in

expression, we can get:

y′′=(y5+y6)+(Δy1+Δy2+Δy3) (Formula 10)

It can be seen from formula 10 that the first term in the y'' expression is the sum of the admittances of the lines connected to the node b1 and the external area (that is, the sum of the admittances of the eliminated lines connected to the node b1), and the second term is the sum of the elements in the row where node b1 is located in the matrix ΔY _BB .

From the above analysis, it can be seen that the change of the matrix elements corresponding to the boundary area in the equivalent simplified admittance matrix can be simply determined to determine the The reactance parameter, and the reactance parameter of the connection branch added between each node in the boundary area, so as to realize the network reconstruction.

According to the above Figure 6, Formula 8 and Formula 10, the reactance parameters of the newly added branch and the newly added generator related to node b1 in the boundary area can be obtained. The specific parameters are shown in Table 1:

Table 1

The processing methods of the nodes b2 and b3 in the boundary area are the same as the processing method of the node b1, and will not be repeated here.

It can be seen from the above equivalent simplification steps that the reactance parameters of the newly added components in the boundary area can be obtained simply by calculating ΔY _BB . It can be seen from the above formula 4 that in solving ΔY _BB it is necessary to perform an inverse operation on the block matrix Y _CC . In the actual power grid, considering that the scale of the boundary area is generally small, generally 4 to 6 nodes, the inversion operation of the matrix can be replaced by the solution method of the linear equation. In one embodiment, determining the variation matrix of the matrix elements corresponding to the boundary area in the equivalent node admittance matrix may include: determining the number of nodes in the boundary area; when the number of nodes in the boundary area is less than a predetermined threshold Next, the method of solving linear equations is used to calculate the variation matrix. Wherein, the predetermined threshold may be 4 to 6, which is specifically selected according to actual needs, which is not limited in the present invention. That is, the method of matrix inversion is replaced by the method of solving linear equations, so that the amount of calculation can be effectively reduced when the number of nodes is small.

Taking the IEEE39 node as an example, the following is an analysis of the simplified method for calculating the equivalent value of the external network of the short-circuit current, as shown in Figure 7, which is a schematic diagram of the network structure division of the IEEE39 node.

As shown in Figure 7, the boundary area includes three nodes: new14, new18 and new25, where the reference capacity SB=100MVA, reference voltage VB=Vav=345kV, calculate ΔY _BB in the order of: new14, new18, new25, calculate The result is shown in Equation 11:

${\mathrm{\ΔY}}_{\mathrm{BB}}=\left[\begin{array}{ccc}-21.321760& -12.475537& -1.319840\\ -12.475537& -79.942309& -8.457436\\ -1.319840& -8.457436& -13.676654\end{array}\right]$ (Formula 11)

From the calculation formula in step S3 above, the newly added elements on each boundary node and the reactance values of each newly added element are calculated according to the value of ΔY _BB in formula 11, as shown in Table 2.

Table 2

The PSD-SCCP software is used to scan the three-phase short-circuit current of the network before and after the equivalence. The load, line resistance, line charging power and non-standard transformation ratio of the transformer are not considered in the calculation. The scan results of the short-circuit current of each node in the research area before and after the equivalence are as follows: Table 3 shows.

table 3

factory station Before equivalence/kA After equivalence/kA Difference/kA new1 9.783 9.783 0 new2 15.820 15.819 -0.001 new3 12.428 12.426 -0.002

new4 11.331 11.330 -0.001 new5 11.599 11.599 0 new6 11.950 11.950 0 new7 9.511 9.511 0 new8 9.893 9.893 0 new9 9.472 9.472 0 new10 11.047 11.047 0 new11 10.770 10.770 0 new12 4.657 4.656 0 new13 10.396 10.395 -0.001

It can be seen from the above Table 3 that only the short-circuit current values of nodes new2, new3, new4, and new13 have slight differences before and after the equivalence. Further analysis shows that these four nodes are directly connected with the boundary area, and the short-circuit current error It can be attributed to the rounding error, that is, when adding the reactance of the newly added branch and the newly added equivalent generator in the PSD-SCCP software, the calculated data is rounded, which leads to a small difference in the calculated value of the short-circuit current of the nearby nodes. difference. The analysis and calculation results on the IEEE39 node system verify that the method provided by the embodiment of the present invention can ensure the calculation accuracy of the short-circuit current.

In the above-mentioned embodiments of the present invention, it is provided that in the calculation process of the short-circuit current of the regional power grid, the equivalent simplification process is performed on the external power grid, and the grid connection form of the boundary area is reconstructed after the equivalent simplification, that is, the external network is equivalent to a new The form of adding lines and new generators is incorporated into the boundary area, so that only the grid data of the research area and the boundary area are retained, thereby significantly reducing the grid scale for short-circuit current calculation, and reducing the requirements for computer memory and simulation software , which improves the work efficiency of power grid operation analysts.

Based on the same inventive concept, an embodiment of the present invention also provides a regional power grid short-circuit current analysis device, as described in the following embodiments. Since the problem-solving principle of the regional power grid short-circuit current analysis device is similar to the regional power grid short-circuit current analysis method, the implementation of the regional power grid short-circuit current analysis device can refer to the implementation of the regional power grid short-circuit current analysis method, and the repetition will not be repeated. As used below, the term "unit" or "module" may be a combination of software and/or hardware that realizes a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementations in hardware, or a combination of software and hardware are also possible and contemplated. Fig. 8 is a kind of structure block diagram of the short-circuit current analysis device of regional power grid of the embodiment of the present invention, as shown in Fig. 8, comprises: area division module 801, equivalent value simplification module 802, and analysis module 803, the structure is carried out below illustrate.

The area division module 801 is used to divide the power grid system into areas: divide the areas that need to analyze and calculate the short-circuit current level into the research areas, divide the areas that have direct contact with the research area into the boundary areas, and divide the areas other than the research area and the boundary area The area of the country is classified as an external area;

The equivalent simplification module 802 is used to perform equivalent simplification on the boundary area and the external area to form an equivalent boundary area, and obtain an equivalent power grid system composed of the research area and the equivalent boundary area;

The analysis module 803 is configured to analyze and calculate the short-circuit current level in the research area according to the equivalent power grid system.

In one embodiment, the above-mentioned equivalent simplification module 802 includes: a construction unit for constructing the node admittance matrix of the power grid system in the order of the external area, the boundary area and the research area; a simplification unit for eliminating The part of the outer area in the nodal admittance matrix forms the post-equivalent nodal admittance matrix that only retains the boundary area and the research area; the matrix determination unit is used to determine the change of the matrix elements corresponding to the boundary area in the post-equivalent nodal admittance matrix Quantity matrix; parameter determination unit, used to determine the added generator, the increased connection branch in the boundary area after the equivalence according to the variation matrix, and the reactance parameter of the increased generator and the reactance of the increased connection branch Parameters; a reconfiguration unit, used for performing an operation according to the increased generator, the increased connection branch, the increased reactance parameter of the generator, the increased reactance parameter of the connected branch, and the connection mode between the generator and the connected branch The network is reconfigured to form an equivalent power grid system.

In one embodiment, the parameter determination unit includes: a first node number determination subunit, used to determine the node numbers at both ends of the added connection branch; a first parameter determination subunit, used to obtain the difference between the two The negative reciprocal of the element corresponding to the node number of the end is used as the reactance parameter of the added connection branch.

In one embodiment, the parameter determination unit includes: a second node number determination subunit, used to determine the node number of the node connected to the added generator; The admittance of the connecting branch directly connected to the node and each element on the row of the node number in the variation matrix are summed to obtain the total admittance; the second parameter determines the subunit, which is used to take the reciprocal of the total admittance as the increase The reactance parameters of the generator.

In one embodiment, the matrix determination unit includes: a node number determination subunit, configured to determine the number of nodes in the boundary area; a calculation subunit, used to determine the number of nodes in the boundary area if the number is less than a predetermined threshold, using The method of linear equation solving computes the delta matrix. In a specific implementation, the aforementioned predetermined threshold may take a value of 6.

In another embodiment, software is also provided, and the software is used to implement the technical solutions described in the above embodiments and preferred implementation manners.

In another embodiment, there is also provided a storage medium, in which the software is stored, the storage medium includes but not limited to: optical discs, floppy disks, hard disks, rewritable memories, and the like.

From the above description, it can be seen that the embodiment of the present invention achieves the following technical effects: divide the area in the grid system that needs to analyze and calculate the short-circuit current level into the research area, and then divide the area directly connected with the research area into the boundary area, divide the area except the study area and the boundary area into external areas, then simplify the grid system equivalent to a grid system that only includes the study area and the equivalent boundary area, and finally pass the equivalent grid system Analyzing and calculating the short-circuit current level of the research area, because there is no external area in the grid system after equivalent simplification, so the amount of data required for the analysis and calculation of the short-circuit current level will be significantly reduced. The above method effectively solves the technical problem in the prior art that it is difficult to reduce the amount of data in short-circuit current analysis while ensuring the calculation accuracy of short-circuit current, and achieves the reduction of short-circuit current analysis on the basis of ensuring the calculation accuracy of short-circuit current Technical effects of data volume and computation volume.

Obviously, those skilled in the art should understand that each module or each step of the above-mentioned embodiments of the present invention can be implemented by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed among multiple computing devices. Optionally, they may be implemented in program code executable by a computing device, thereby, they may be stored in a storage device to be executed by a computing device, and in some cases, may be implemented in a code different from that described herein The steps shown or described are executed in sequence, or they are fabricated into individual integrated circuit modules, or multiple modules or steps among them are fabricated into a single integrated circuit module for implementation. Thus, embodiments of the invention are not limited to any specific combination of hardware and software.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, various modifications and changes may be made to the embodiments of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (12)

1. A method for analyzing the short-circuit current of a regional power grid, is characterized in that, comprising: Regional division of the power grid system: divide the area that needs to analyze and calculate the short-circuit current level into the research area, divide the area that has direct contact with the research area into the boundary area, and divide the areas other than the research area and the boundary area into the external area; The boundary area and the external area are equivalently simplified to form an equivalent boundary area, and an equivalent power grid system composed of the research area and the equivalent boundary area is obtained; According to the equivalent grid system, the short-circuit current level in the research area is analyzed and calculated. 2. The method according to claim 1, wherein the boundary area and the outer area are carried out to equivalent simplification to form an equivalent boundary area, and to obtain an equivalent value consisting of the research area and the equivalent boundary area After the grid system, including: Construct the node admittance matrix of the power grid system in the order of the external area, the boundary area and the research area; Use the Gaussian elimination method to eliminate the part of the outer region in the nodal admittance matrix to form an equivalent post-nodal admittance matrix that only retains the boundary region and the research region; After determining the equivalence, the change matrix of the matrix elements corresponding to the boundary area in the node admittance matrix; Determine the added generator, the added connection branch, and the added reactance parameter of the generator and the added reactance parameter of the connected branch in the boundary area after equivalence according to the variation matrix; According to the determined added generators, added connected branches, added reactance parameters of generators, and added reactance parameters of connected branches, the network is reconfigured to form an equivalent grid system. 3. The method according to claim 2, characterized in that, determining the reactance parameter of the connected branch increased in the boundary area after the equivalence according to the variation matrix comprises: Determine the node numbers at both ends of the added connection branch; Take the negative reciprocal of the elements corresponding to the node numbers at both ends in the variation matrix, as the reactance parameter of the added connecting branch. 4. The method according to claim 2, characterized in that, determining the reactance parameter of the generator added in the boundary region after equivalence according to the variation matrix comprises: determine the node number of the node connected to the added generator; The total admittance is obtained by adding the admittance of the connecting branch directly connected to the node of the node number in the external area, and each element on the row of the node number in the variation matrix; Take the reciprocal of the total admittance as the reactance parameter of the added generator. 5. method as claimed in claim 2, it is characterized in that, determine the variation matrix of the matrix element corresponding to boundary area in the nodal admittance matrix after equivalence, comprising: Determine the number of nodes in the boundary area; In the case that the number of nodes in the boundary area is less than a predetermined threshold, a linear equation solution method is used to calculate the variation matrix. 6. The method according to claim 5, wherein the predetermined threshold is six. 7. A regional power grid short-circuit current analysis device, characterized in that it comprises: The regional division module is used for regional division of the power grid system: divide the areas that need to analyze and calculate the short-circuit current level into the research area, divide the areas that have direct contact with the research area into the boundary area, and divide the areas other than the research area and the boundary area Territory is divided into external areas; The equivalent simplification module is used to perform equivalent simplification of the boundary area and the external area to form an equivalent boundary area, and obtain an equivalent power grid system composed of the research area and the equivalent boundary area; The analysis module is used to analyze and calculate the short-circuit current level in the research area according to the equivalent power grid system. 8. The device according to claim 7, wherein the equivalent simplification module comprises: A construction unit for constructing the node admittance matrix of the power grid system in the order of the external area, the boundary area and the research area; The simplified element is used to eliminate the part of the outer region in the nodal admittance matrix by using the Gaussian elimination method to form an equivalent post-nodal admittance matrix that only retains the boundary region and the research region; A matrix determining unit is used to determine the variation matrix of the matrix elements corresponding to the boundary area in the equivalent node admittance matrix; A parameter determination unit, configured to determine the added generator, the added connection branch, and the added reactance parameter of the generator and the added reactance parameter of the connected branch in the equivalent boundary area according to the variation matrix; The reconstruction unit is configured to perform network reconfiguration according to the added generator, the added connection branch, the added reactance parameter of the generator, and the added reactance parameter of the connected branch to form an equivalent grid system. 9. The device according to claim 8, wherein the parameter determining unit comprises: The first node number determination subunit is used to determine the node numbers at both ends of the added connection branch; The first parameter determination subunit is used to take the negative reciprocal of the elements corresponding to the node numbers at both ends in the variation matrix as the reactance parameter of the added connection branch. 10. The device according to claim 8, wherein the parameter determining unit comprises: The second node number determination subunit is used to determine the node number of the node connected to the added generator; The accumulating unit is used to add the admittance of the connecting branch directly connected to the node of the node number in the external area, and each element on the row of the node number in the variation matrix to obtain the total admittance; The second parameter determination subunit is used to take the reciprocal of the total admittance as the reactance parameter of the added generator. 11. The device according to claim 8, wherein the matrix determining unit comprises: The node number determination subunit is used to determine the number of nodes in the boundary area; The calculation subunit is used to calculate the variation matrix by using a linear equation solution method when the number of nodes in the boundary area is less than a predetermined threshold. 12. The device according to claim 11, wherein the predetermined threshold is 6.

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