Fault calculation method, device and equipment for power distribution network containing distributed power supply, and medium

Abstract

The invention provides a fault calculation method and device for a power distribution network containing a distributed power supply, equipment and a medium, and relates to the technical field of power distribution networks. In response to the broken line grounding complex fault, after a first node injection current matrix of the normal component network is obtained, a first node voltage sequence component matrix of the fault component network is established in combination with the positive and negative zero sequence impedance matrixes; correcting the DG positive-sequence injection current according to the positive-sequence voltage of the grid-connected point of the distributed power supply to obtain the corrected DG positive-sequence injection current, and correcting the first node voltage sequence component matrix to obtain a second node voltage sequence component matrix; weighting the first node voltage sequence component matrix and the second node voltage sequence component matrix to obtain a fault voltage matrix; and if the fault voltage matrix meets the fault calculation stability condition, obtaining the fault electrical quantity of the power distribution network according to the fault voltage matrix, and taking the fault electrical quantity as the fault information of the broken line grounding complex fault so as to reduce the deviation degree between the fault information and the actual condition.

Description

Technical Field

[0001] This application relates to the field of power distribution network technology, and in particular to a method, apparatus, equipment and medium for calculating faults in power distribution networks containing distributed power sources. Background Technology

[0002] With the rapid construction of new power systems, the large-scale integration of distributed generation (DG) into distribution networks has become a key path for promoting energy structure transformation and the development of clean energy. However, the randomness, volatility, and multi-type grid connection characteristics of DG (such as photovoltaic, wind power, and energy storage) significantly alter the fault characteristics of distribution networks. Among these, the combined fault of open circuit and ground fault (referred to as "open circuit and ground fault") has become a major hidden danger threatening the safe operation of distribution networks due to its high concealment and complex fault characteristics.

[0003] Currently, the methods for calculating faults in distribution networks with distributed generation (DG) mainly focus on single fault types, which are difficult to adapt to the complex operating conditions of open-circuit grounding faults. The DG equivalent models (such as constant power sources or current sources) that are often used have problems in calculating faults for open-circuit grounding faults, where the calculation results deviate from the actual operating conditions. Summary of the Invention

[0004] This application provides a method, apparatus, equipment, and medium for calculating faults in distribution networks containing distributed power sources, in order to improve the versatility, efficiency, and accuracy of fault calculation for ground faults caused by disconnection in distribution networks containing distributed power sources.

[0005] In a first aspect, embodiments of this application provide a method for calculating faults in a distribution network containing distributed power sources, including: responding to the detection of a ground fault in the distribution network and obtaining the first node injection current matrix of the normal component network in the distribution network;

[0006] Based on the positive and negative zero-sequence impedance matrix and the first node injection current matrix of the network structure corresponding to the distribution network, the first node voltage sequence component matrix of the fault component network in the distribution network is established.

[0007] Based on the positive sequence voltage of the distributed generation connection point in the first node voltage sequence component matrix in the distribution network, the positive sequence injection current of DG in the first node injection current matrix is ​​corrected to obtain the corrected positive sequence injection current of DG.

[0008] The first node voltage sequence component matrix is ​​corrected based on the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix.

[0009] The fault voltage matrix of the distribution network is obtained by weighting the first node voltage sequence component matrix and the second node voltage sequence component matrix.

[0010] If the fault voltage matrix satisfies the fault calculation stability condition, the fault electrical quantities of the distribution network are calculated based on the fault voltage matrix, and the fault electrical quantities are used as the fault information of the open-circuit grounding re-fault. The fault electrical quantities include node voltage, branch current and DG output current.

[0011] In one possible implementation, based on the positive and negative zero-sequence impedance matrices and the first node injection current matrix of the network structure corresponding to the distribution network, the first node voltage sequence component matrix of the fault component network in the distribution network is established, including:

[0012] Obtain fault parameters in the network structure;

[0013] Based on the first node injection current matrix and fault parameters, the second node injection current matrix of the fault component network is established.

[0014] The first node voltage sequence component matrix of the fault component network is obtained by superimposing the first node injection current matrix, the second node injection current matrix, and the positive and negative zero sequence impedance matrices.

[0015] In one possible implementation, obtaining fault parameters in the network structure includes:

[0016] Identify the single-phase open circuit node where the single-phase open circuit occurred;

[0017] Based on the positional relationship between the single-phase disconnection node and the power supply side of the distribution network, one node is identified as the ground fault node from among the single-phase disconnection nodes.

[0018] Obtain the grounding resistance corresponding to the grounding short-circuit node, and use the grounding resistance, single-phase open-circuit node, and grounding short-circuit node as fault parameters.

[0019] In one possible implementation, a second node injection current matrix of the fault component network is established based on the first node injection current matrix and fault parameters, including:

[0020] Based on the positive and negative zero-sequence impedance matrix and the first node injection current matrix, the third node voltage sequence component matrix of the normal component network is established.

[0021] Based on the fault parameters, the impedance information of the faulty node in the network structure is obtained;

[0022] The positive sequence voltage of the fault node is determined by the third node voltage sequence component matrix.

[0023] By using the pre-defined boundary condition equations for single-phase open-circuit faults and ground short-circuit faults, and based on impedance information and the positive sequence voltage of the fault node, the fault current vector is obtained.

[0024] Based on the fault current vector, a second node injection current matrix is ​​established for the fault component network.

[0025] The boundary condition equations characterize the equational relationship between impedance information, positive sequence voltage at the fault node, and fault current vector.

[0026] In one possible implementation, the construction of the positive and negative zero-sequence impedance matrices of the network structure includes:

[0027] Identify single-phase open-circuit nodes and ground short-circuit nodes in the network structure;

[0028] Obtain the branch impedance information between single-phase open-circuit nodes and ground short-circuit nodes;

[0029] Based on the branch impedance information, the positive and negative zero-sequence impedance matrices of the network structure are obtained.

[0030] In one possible implementation, the first node voltage sequence component matrix is ​​corrected based on the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix, including:

[0031] Obtain the positive sequence voltage of the DG grid connection point in the first node voltage sequence component matrix;

[0032] The DG positive sequence injection current in the first node injection current matrix is ​​corrected based on the grid connection point positive sequence voltage to obtain the corrected DG positive sequence injection current.

[0033] The first node voltage sequence component matrix is ​​corrected based on the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix.

[0034] In one possible implementation, the first node voltage sequence component matrix is ​​corrected based on the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix, including:

[0035] The first node injection current matrix is ​​updated based on the corrected DG positive sequence injection current to obtain the updated first node injection current matrix.

[0036] Based on the updated first node injection current matrix and the fault parameters in the network structure, the updated second node injection current matrix of the fault component network is established.

[0037] The updated first node injection current matrix, the updated second node injection current matrix, and the positive and negative zero sequence impedance matrices are superimposed to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix.

[0038] In a second aspect, embodiments of this application provide a distribution network fault calculation device with distributed power sources, including: a fault response unit, used to respond to the detection of a ground fault in the distribution network and obtain the first node injection current matrix of the normal component network in the distribution network;

[0039] The modeling unit is used to establish the first node voltage sequence component matrix of the fault component network in the distribution network based on the positive and negative zero sequence impedance matrix and the first node injection current matrix of the network structure corresponding to the distribution network.

[0040] The DG injection current correction unit is used to correct the DG positive sequence injection current in the first node injection current matrix based on the positive sequence voltage of the distributed power generation grid connection point in the first node voltage sequence component matrix, so as to obtain the corrected DG positive sequence injection current.

[0041] The voltage sequence component correction unit is used to correct the first node voltage sequence component matrix based on the corrected positive sequence injection current of DG, so as to obtain the second node voltage sequence component matrix.

[0042] The synthesis unit is used to perform weighted processing on the first node voltage sequence component matrix and the second node voltage sequence component matrix to obtain the fault voltage matrix of the distribution network.

[0043] The result output unit is used to calculate the fault electrical quantities of the distribution network based on the fault voltage matrix if the fault voltage matrix satisfies the fault calculation stability condition, and to use the fault electrical quantities as the fault information of the open-circuit grounding re-fault. The fault electrical quantities include node voltage, branch current and DG output current.

[0044] Thirdly, embodiments of this application provide an electronic device, including: a memory and a processor;

[0045] The memory stores the instructions that the computer executes;

[0046] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0047] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0048] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0049] The method, electronic device, storage medium, and program product for calculating distribution network faults including distributed generation provided in this application embodiment respond to the detection of a ground fault due to a disconnection in the distribution network and obtain the first node injection current matrix of the normal component network in the distribution network; based on the positive and negative zero-sequence impedance matrix of the network structure corresponding to the distribution network and the first node injection current matrix, establish the first node voltage sequence component matrix of the fault component network in the distribution network; according to the positive sequence voltage of the distributed generation grid connection point in the first node voltage sequence component matrix, correct the DG positive sequence injection current in the first node injection current matrix to obtain the corrected DG positive sequence injection current; correct the first node voltage sequence component matrix according to the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix; perform weighted processing on the first node voltage sequence component matrix and the second node voltage sequence component matrix to obtain the fault voltage matrix of the distribution network; if the fault voltage matrix satisfies the fault calculation stability condition, calculate the fault electrical quantities of the distribution network according to the fault voltage matrix, and use the fault electrical quantities as the fault information of the ground fault due to a disconnection. The fault electrical quantities include node voltage, branch current, and DG output current. Therefore, this application, through targeted fault calculation of open-circuit and grounding faults in the designed distribution network, can effectively decouple the effects of open-circuit and grounding faults, avoiding calculation deviations caused by coupling characteristics in traditional methods. Furthermore, fault information is acquired only when the obtained fault voltage matrix meets preset fault calculation stability conditions. Meeting these stability conditions indicates that the calculation results tend to be stable, ensuring the accuracy of subsequently acquired fault information and reducing the deviation between fault information and actual conditions. This provides reliable technical support for new distribution networks with distributed power source integration, significantly reducing fault response time and economic loss risks. Attached Figure Description

[0050] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0051] Figure 1 This is a schematic diagram of one implementation environment involved in this application;

[0052] Figure 2 A flowchart illustrating the fault calculation process for a distribution network containing distributed generation sources, provided in this application;

[0053] Figure 3 This is a schematic diagram illustrating a ground fault re-fault caused by a disconnection in one embodiment of this application;

[0054] Figure 4 This is a flowchart illustrating the steps of a method for calculating faults in a distribution network containing distributed power sources in one embodiment.

[0055] Figure 5A schematic diagram of the structure of the distribution network fault calculation device containing distributed power sources provided in this application;

[0056] Figure 6 A schematic diagram of the structure of the electronic device provided in this application.

[0057] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0058] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0059] Figure 1 This is a schematic diagram of an implementation environment involved in this application, such as... Figure 1 As shown, the implementation environment includes a distribution network 10 with distributed power sources and a server 20.

[0060] Server 20 is used to respond to the detected open-circuit grounding re-fault in distribution network 10, and to obtain the first node injection current matrix of the normal component network in distribution network 10; based on the positive and negative zero-sequence impedance matrix of the network structure corresponding to distribution network 10 and the first node injection current matrix, to establish the first node voltage sequence component matrix of the fault component network in distribution network 10; according to the positive sequence voltage of the distributed generation grid connection point in distribution network 10 in the first node voltage sequence component matrix, the DG positive sequence injection current in the first node injection current matrix is ​​corrected to obtain the corrected DG positive sequence injection current; the first node voltage sequence component matrix is ​​corrected according to the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix; the first node voltage sequence component matrix and the second node voltage sequence component matrix are weighted to obtain the fault voltage matrix of distribution network 10; if the fault voltage matrix satisfies the fault calculation stability condition, the fault electrical quantities of the distribution network are calculated according to the fault voltage matrix, and the fault electrical quantities are used as the fault information of the open-circuit grounding re-fault. The fault electrical quantities include node voltage, branch current and DG output current.

[0061] It should be noted that, Figure 1In the implementation environment shown, server 20 can be a standalone server or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDN), and big data and artificial intelligence platforms. No restrictions are imposed here.

[0062] As can be seen from the above scenarios, existing technologies suffer from the problem that traditional fault calculation methods are ill-suited to the complex operating conditions of open-circuit and grounding faults, resulting in calculation results that deviate from the actual operating state and thus lack accuracy. The fault calculation method for distribution networks containing distributed power sources provided in this application, through targeted fault calculation of open-circuit and grounding faults in the designed distribution network, can effectively decouple the effects of open-circuit and grounding faults, avoiding the calculation deviations caused by coupling characteristics in traditional methods.

[0063] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0064] Figure 2 The flowchart for fault calculation in a distribution network containing distributed generation provided in this application is as follows: Figure 2 As shown, the method includes:

[0065] S201. Upon detecting a ground fault in the distribution network, obtain the first node injection current matrix of the normal component network in the distribution network.

[0066] In this context, "open-circuit grounding re-fault" is an abbreviation for a composite fault involving both an open circuit and a ground short circuit. The normal component network is extracted from the "post-fault network" and retains only all normally operating power sources. The corresponding fault component network is extracted from the "post-fault network" and retains only the fault itself as the excitation source. In the embodiments provided in this application, the normal component network and the fault component network together form the distribution network in which the open-circuit grounding re-fault occurs.

[0067] In this embodiment, after a ground fault occurs in the distribution network, a composite fault is responded to. First, the first node injection current matrix of the normal component network in the distribution network is obtained to provide a data basis for fault calculation.

[0068] S202. Based on the positive and negative zero-sequence impedance matrix and the first node injection current matrix of the network structure corresponding to the distribution network, establish the first node voltage sequence component matrix of the fault component network in the distribution network.

[0069] Among them, the positive and negative zero-sequence impedance matrix is ​​a key matrix for asymmetric fault analysis of power systems. It can systematically characterize the impedance characteristics of power network components under different sequences in matrix form. In this embodiment, the positive and negative zero-sequence impedance matrix is ​​the basis for establishing the matrix in the fault component network and calculating the voltage sequence components of each node after the fault.

[0070] In this embodiment, voltage sequence component modeling is achieved based on the positive and negative zero-sequence impedance matrix and the first node injection current matrix of the network structure corresponding to the distribution network. The first node voltage sequence component matrix of the fault component network is constructed as the basis matrix for obtaining the fault voltage matrix.

[0071] S203. Based on the positive sequence voltage of the distributed generation connection point in the first node voltage sequence component matrix, the positive sequence injection current of DG in the first node injection current matrix is ​​corrected to obtain the corrected positive sequence injection current of DG.

[0072] The distributed generation (DG) grid connection point is the physical interface point for electrical connection and energy exchange in the distribution network. When a ground fault occurs in the distribution network, the DG grid connection point is also the injection point for fault components. The fault generates unbalanced voltage and current (i.e., positive, negative, and zero-sequence components) in the grid, which propagate to the DG grid connection point, altering its voltage. Therefore, this application uses the positive-sequence voltage of the DG grid connection point as the basis for correcting and updating various matrices and data, ensuring that the fault calculation results conform to the actual state of the distribution network and avoiding calculation deviations caused by the coupling characteristics of ground faults.

[0073] In this embodiment, during the DG injection current correction stage, the DG positive sequence injection current in the first node injection current matrix is ​​corrected based on the positive sequence voltage of the distributed power grid connection point to obtain the corrected DG positive sequence injection current.

[0074] S204. Based on the corrected positive sequence injection current of DG, the first node voltage sequence component matrix is ​​corrected to obtain the second node voltage sequence component matrix.

[0075] In this embodiment, during the voltage sequence component correction stage, the first node voltage sequence component matrix is ​​corrected based on the corrected positive sequence injection current of DG to obtain the second node voltage sequence component matrix of the fault component network.

[0076] S205. Weight the first node voltage sequence component matrix and the second node voltage sequence component matrix to obtain the fault voltage matrix of the distribution network.

[0077] In other embodiments, the weights for the weighted processing can be determined based on a preset compression coefficient, and the corresponding expression for the fault voltage matrix is:

[0078]

[0079] in, For the fault voltage matrix, This is the first node voltage sequence component matrix. This is the second node voltage sequence component matrix. The compression factor is 1.

[0080] S206. If the fault voltage matrix satisfies the fault calculation stability condition, the fault electrical quantities of the distribution network are calculated based on the fault voltage matrix, and the fault electrical quantities are used as the fault information of the open-circuit grounding re-fault. The fault electrical quantities include node voltage, branch current and DG output current.

[0081] The fault calculation stability condition is a preset criterion used to determine whether the fault voltage matrix meets the fault calculation stability requirements. In this embodiment, if the fault voltage matrix meets the fault calculation stability condition, the fault electrical quantities of the distribution network are calculated based on the fault voltage matrix and the corresponding current matrix, and the fault electrical quantities are used as the fault information for the open-circuit grounding re-fault. The fault electrical quantities include node voltage, branch current, and DG output current.

[0082] The fault calculation method for distribution networks containing distributed generation provided in this application includes, on the one hand, after constructing the first node voltage sequence component matrix of the fault component network, modifying and weighting the first node voltage sequence component matrix based on the positive sequence voltage of the distributed generation grid connection point, which serves as the fault component injection point, to obtain a fault voltage matrix that can be used to determine whether the fault calculation stability condition is met. On the other hand, after obtaining each fault voltage matrix, it is determined whether it meets the preset fault calculation stability condition. The voltage matrix that meets the fault calculation stability condition is used to obtain high-precision fault information.

[0083] As can be seen, this application, through its targeted fault calculation for open-circuit and grounding faults in the designed distribution network, can effectively decouple the effects of open-circuit and grounding faults, avoiding calculation deviations caused by coupling characteristics in traditional methods. Furthermore, fault information is acquired only when the obtained fault voltage matrix meets the preset fault calculation stability conditions. Meeting these stability conditions indicates that the calculation results tend to be stable and more consistent with actual fault voltage conditions, thus ensuring the accuracy of subsequently acquired fault information and reducing the deviation between fault information and actual conditions. This provides reliable technical support for new distribution networks with distributed power source integration, significantly reducing fault response time and economic loss risks.

[0084] In the embodiments provided in this application, the process from obtaining the first node injection current matrix of the normal component network to determining whether the fault voltage matrix meets the fault calculation stability condition is actually an iterative loop process. When the fault calculation stability condition is not met, that is, when the preset convergence condition is not met, the first node injection current matrix is ​​updated according to the corrected DG positive sequence injection current, and the fault voltage matrix obtained by applying the fault voltage matrix obtained in this application is applied according to the updated first node injection current matrix to obtain a new fault voltage matrix, until the fault calculation stability condition is met.

[0085] Furthermore, the stability condition for fault calculation can be: obtaining the differences between the positive and negative zero-sequence components of corresponding voltage elements in the fault voltage matrix and the fault voltage matrix output in the previous iteration, and then determining whether the maximum difference among the positive and negative zero-sequence component differences is less than a preset threshold. Moreover, before the first iteration, there is a step of obtaining the fault voltage matrix provided in this application to form an initial fault voltage matrix, which is used to compare with the fault voltage matrix output in the first iteration.

[0086] In one embodiment of this application, before the iteration loop begins, a matrix can be established to store the voltage values ​​in the fault voltage matrix obtained at the end of each loop. The stability condition for fault calculation can be expressed as:

[0087]

[0088] In the formula, The initial values ​​in the initial fault voltage matrix of the n nodes are set before the first iteration loop; Substitute the data from the (k+1)th column of the matrix after the kth iteration into the fault voltage matrix. ; The maximum difference between the positive and negative zero-sequence components of the node voltage and the previous cycle (considering all nodes, one positive and one negative zero-sequence). The convergence condition is met and the loop is exited when all of them are less than the preset threshold ε (usually 0.0001).

[0089] In an exemplary embodiment of this application, the step of establishing the first node voltage sequence component matrix of the fault component network in the distribution network based on the positive and negative zero-sequence impedance matrix and the first node injection current matrix of the network structure corresponding to the distribution network may specifically include:

[0090] Obtain fault parameters in the network structure;

[0091] Based on the first node injection current matrix and fault parameters, the second node injection current matrix of the fault component network is established.

[0092] The first node voltage sequence component matrix of the fault component network is obtained by superimposing the first node injection current matrix, the second node injection current matrix, and the positive and negative zero sequence impedance matrices.

[0093] The fault parameters include the location of nodes such as grounding resistance, single-phase open circuit nodes, and ground short circuit nodes. In another embodiment, the step of obtaining fault parameters in the network structure may specifically include:

[0094] Identify the single-phase open circuit node where the single-phase open circuit occurred;

[0095] Based on the positional relationship between the single-phase disconnection node and the power supply side of the distribution network, one node is identified as the ground fault node from among the single-phase disconnection nodes.

[0096] Obtain the grounding resistance corresponding to the grounding short-circuit node, and use the grounding resistance, single-phase open-circuit node, and grounding short-circuit node as fault parameters.

[0097] Based on the positional relationship between the single-phase disconnection node and the power supply side of the distribution network, one node is identified as a ground fault node from the single-phase disconnection nodes. Specifically, the node closest to the power supply side of the distribution network is determined to be in a state of power supply side grounding, and is thus identified as a ground fault node, thereby enabling accurate acquisition of the grounding resistance.

[0098] Figure 3 This is a schematic diagram illustrating a ground fault re-fault caused by a disconnection in one embodiment of this application. Figure 3 As shown, in the two fault points of the open-circuit grounding fault on the left, node P is the grounding short-circuit node; in the two fault points of the open-circuit grounding fault on the right, Q is the grounding short-circuit node.

[0099] Thus, through this embodiment, this application achieves a precise mapping from the physical fault space to the computational parameter space by determining the single-phase open circuit node and the ground short circuit node, and by obtaining the grounding resistance, providing a foundation for subsequent fault calculation.

[0100] In the above embodiment, after obtaining the fault parameters, a second node injection current matrix of the fault component network is established based on the first node injection current matrix and the fault parameters. The first node injection current matrix, the second node injection current matrix, and the positive and negative zero-sequence impedance matrices are superimposed to obtain the first node voltage sequence component matrix of the fault component network, which can be expressed as:

[0101]

[0102] in, The positive and negative zero sequence impedance matrix, Inject the current matrix into the first node. Inject the current matrix into the second node. To overlay the resulting matrix, This is the first node voltage sequence component matrix.

[0103] Thus, through the above embodiments, this application preliminarily clarifies the fault disturbances in the distribution network through linear superposition calculation, and uses the first node voltage sequence component matrix of the fault component network to represent them, providing a key initial input for subsequent response correction.

[0104] In an exemplary embodiment of this application, the step of establishing the second node injection current matrix of the fault component network based on the first node injection current matrix and fault parameters may specifically include:

[0105] Based on the positive and negative zero-sequence impedance matrix and the first node injection current matrix, the third node voltage sequence component matrix of the normal component network is established.

[0106] Based on the fault parameters, the impedance information of the faulty node in the network structure is obtained;

[0107] The positive sequence voltage of the fault node is determined by the third node voltage sequence component matrix.

[0108] By using the pre-defined boundary condition equations for single-phase open-circuit faults and ground short-circuit faults, and based on impedance information and the positive sequence voltage of the fault node, the fault current vector is obtained.

[0109] Based on the fault current vector, a second node injection current matrix is ​​established for the fault component network.

[0110] Among them, the fault nodes include single-phase open circuit nodes and ground short circuit nodes, and the impedance information includes the self impedance of single-phase open circuit nodes and ground short circuit nodes, as well as the mutual impedance between single-phase open circuit nodes and ground short circuit nodes.

[0111] The boundary condition equations characterize the equational relationship between impedance information, the positive-sequence voltage at the fault node, and the fault current vector, and can be expressed as:

[0112]

[0113] in, The self-impedance of a single-phase open circuit node. The self-impedance of the ground short-circuit node (i=1,2,0); This represents the mutual impedance between a single-phase open-circuit node and a ground-short-circuit node. (i=1,2,0); R f This is the fault resistor.

[0114] Let P and Q represent the positive sequence voltages at a single-phase open-circuit node, and let Q be the fault ports. Then, the positive sequence components of the port voltages at the open-circuit faults in the normal component network are:

[0115]

[0116] This represents the positive sequence voltage of the short-circuit node. When the ground short-circuit node is point P, When the ground short-circuit node is point Q, .

[0117] Based on the above boundary condition equations, the fault current vector X can be calculated:

[0118]

[0119] In the formula, X1, X2, and X3 are the positive-sequence, negative-sequence, and zero-sequence currents of a single-phase open circuit node, respectively; X4 is the positive-sequence current of a ground short circuit node. Considering that the positive, negative, and zero-sequence fault currents are equal in a ground short circuit fault, it can be represented by only one positive-sequence fault current variable.

[0120] In this embodiment, in order to establish the second node injection current matrix of the fault component network, the third node voltage sequence component matrix of the normal component network is first established based on the positive and negative zero sequence impedance matrix and the first node injection current matrix.

[0121] First nodal injection current matrix of normal component network It can be:

[0122]

[0123] In the formula, the superscript k indicates that this matrix is ​​the data of the kth iteration cycle, and the subscripts 1, 2, and 0 represent the positive, negative, and zero order components, respectively; The injected current of the system power supply has only a positive sequence component and does not change with iteration. , These are the positive-sequence injection currents of the 1st and mth DGs, respectively, but since they are controlled by the positive-sequence voltage, iterative correction is required.

[0124] The third node voltage sequence component matrix of a normal component network It can be:

[0125]

[0126]

[0127] In the formula, for a distribution network model with a total of n nodes, Z represents the positive and negative zero-sequence voltage values ​​at the node in the k-th cycle; 120 It is the positive and negative zero-sequence impedance matrix. , , These represent the positive-sequence, negative-sequence, and zero-sequence voltages of the nth node in the kth cycle, respectively.

[0128] Then, based on the fault parameters, the impedance information of the fault node in the network structure is obtained; the positive sequence voltage of the fault node is determined by the third node voltage sequence component matrix; and the fault current vector is obtained by using the boundary condition equations of the single-phase open circuit fault and the ground short circuit fault, based on the impedance information and the positive sequence voltage of the fault node.

[0129] Finally, based on the fault current vector, the second node injection current matrix of the fault component network is established. This second node injection current matrix can be established by modifying the initial node injection current matrix of the fault component network using the fault current vector. Specifically, first, the initial node injection current matrix of the fault component network is obtained. Where the subscript is the sequence component identifier, corrected according to the fault current vector. The second node injection current matrix is ​​obtained.

[0130] Of the faulty nodes P and Q, only one node P or Q is a ground fault. When the ground fault is P:

[0131] ;

[0132] .

[0133] When the ground short-circuit node is Q:

[0134] ;

[0135] .

[0136] In the formula, and These are the fault injection currents at nodes P and Q of a single-phase open-circuit ground fault. The initial node injection current matrix of the fault component network is corrected based on the obtained fault injection currents to obtain the second node injection current matrix of the fault component network.

[0137] Thus, through the above embodiments, this application uses the boundary condition equations of single-phase open-circuit faults and ground short-circuit faults to accurately transform complex physical fault boundary conditions into a standard, directly usable fault current vector. Then, based on the fault current vector, a second node injection current matrix of the fault component network is established, which is a key bridge connecting the physical description of the fault and the fault calculation.

[0138] In an exemplary embodiment of this application, the steps for constructing the positive and negative zero-sequence impedance matrices of the network structure may specifically include:

[0139] Identify single-phase open-circuit nodes and ground short-circuit nodes in the network structure;

[0140] Obtain the branch impedance information between single-phase open-circuit nodes and ground short-circuit nodes;

[0141] Based on the branch impedance information, the positive and negative zero-sequence impedance matrices of the network structure are obtained.

[0142] Through the above embodiments, this application transforms the physical branch impedance information of the distribution network into positive-sequence, negative-sequence, and zero-sequence node impedance matrices that can be used for accurate quantitative calculations. This describes the mathematical framework of the global electrical connection and transmission characteristics of the distribution network and provides a solid linear network foundation for subsequent fault calculations.

[0143] In an exemplary embodiment of this application, the step of correcting the first node voltage sequence component matrix based on the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix may specifically include:

[0144] Obtain the positive sequence voltage of the DG grid connection point in the first node voltage sequence component matrix;

[0145] The DG positive sequence injection current in the first node injection current matrix is ​​corrected based on the grid connection point positive sequence voltage to obtain the corrected DG positive sequence injection current.

[0146] The first node voltage sequence component matrix is ​​corrected based on the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix.

[0147] In this embodiment, by collecting the positive sequence voltage and node number of the DG grid connection point, different DGs are assigned their own power parameters (rated capacity, active power reference value, etc.). Based on the preset low voltage fault ride-through equation and DG output current limiting equation, the controlled output characteristics during the distributed power source fault are utilized to correct the corresponding DG positive sequence injection current in the first node injection current matrix.

[0148] Then, the first node voltage sequence component matrix is ​​corrected based on the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix.

[0149] Thus, the above embodiments of this application, by using the positive sequence voltage of the grid connection point of the DG to correct the positive sequence injection current of the DG, introduce the dynamic characteristics of distributed generation in the fault calculation process, making the calculation results closer to the actual operation of the distribution network.

[0150] In an exemplary embodiment of this application, the step of correcting the first node voltage sequence component matrix based on the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix may specifically include:

[0151] The first node injection current matrix is ​​updated based on the corrected DG positive sequence injection current to obtain the updated first node injection current matrix.

[0152] Based on the updated first node injection current matrix and the fault parameters in the network structure, the updated second node injection current matrix of the fault component network is established.

[0153] The updated first node injection current matrix, the updated second node injection current matrix, and the positive and negative zero sequence impedance matrices are superimposed to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix.

[0154] Thus, through the above embodiments, this application, after correcting the first node injection current matrix and the second node injection current matrix according to the corrected DG positive sequence injection current, uses linear superposition calculation to clarify a new fault voltage state that the distribution network may reach, which is closer to the real one, and uses the second node voltage sequence component matrix of the fault component network to represent it.

[0155] In one embodiment of this application, when designing the fault calculation method for a distribution network containing distributed power sources provided in this application, the feasibility of the fault calculation method for a distribution network containing distributed power sources can be illustrated by constructing a virtual network result and simulating a ground fault caused by a disconnection. For example... Figure 4 As shown, Figure 4 The following is a flowchart illustrating the steps of a method for calculating faults in a distribution network containing distributed generation sources in one embodiment.

[0156] Step 1: After the single-phase open circuit node where a single-phase open circuit occurs, add a virtual node to form a virtual network structure. The positive and negative zero-sequence impedances between the open circuit node P and the added node Q are both represented by K (K = 106Ω, 107Ω, or any of these are acceptable, which is considered to indicate an open circuit fault between nodes P and Q). After the open circuit node P, if there are other nodes connected to P, change the connection of those other nodes to node Q.

[0157] Step 2: Generate the positive and negative zero-sequence impedance matrix Z based on the node and branch impedance information from Step 1. 120 ;

[0158] Step 3: Input the single-phase open circuit node, the ground short circuit node, and the grounding resistance value R. f ;

[0159] Step 4: Establish the nodal injection current matrix of the normal component network ;

[0160] Step 5: Calculate the nodal voltage sequence component matrix of the normal component network. ;

[0161] Step 6: Calculate the positive and negative zero-sequence fault currents of a single-phase open-circuit fault and a ground fault based on the boundary condition equations for single-phase open-circuit faults and ground faults.

[0162] Step 7: Establish the node injection current matrix of the fault component network ;

[0163] Step 8: Correct based on the calculation results of Step 5 ;

[0164] Step 9: Calculate the node voltage sequence component matrix after the fault based on the superposition. ;

[0165] Step 10: Correct the DG output current;

[0166] Step 11: Repeat steps 4 through 10 to update. and ;

[0167] Step 12: Calculate the node voltage sequence component matrix after fault correction;

[0168] Step 13: Iterative difference calculation and convergence condition determination;

[0169] Step 14: Return to step 4 and begin k+1 iterations of calculation;

[0170] Step 15: Output parameters such as node voltage and branch current.

[0171] Figure 5 The schematic diagram of the distribution network fault calculation device containing distributed generation provided in this application is as follows: Figure 5 As shown, the distribution network fault calculation device 50 containing distributed power sources includes:

[0172] The fault response unit 501 is used to respond to the detection of a ground fault in the distribution network and to obtain the first node injection current matrix of the normal component network in the distribution network.

[0173] Modeling unit 502 is used to establish the first node voltage sequence component matrix of the fault component network in the distribution network based on the positive and negative zero sequence impedance matrix and the first node injection current matrix of the network structure corresponding to the distribution network.

[0174] The DG injection current correction unit 503 is used to correct the DG positive sequence injection current in the first node injection current matrix based on the positive sequence voltage in the first node voltage sequence component matrix of the distributed power grid connection point, so as to obtain the corrected DG positive sequence injection current.

[0175] The voltage sequence component correction unit 504 is used to correct the first node voltage sequence component matrix based on the corrected positive sequence injection current of DG to obtain the second node voltage sequence component matrix.

[0176] Synthesis unit 505 is used to perform weighted processing on the first node voltage sequence component matrix and the second node voltage sequence component matrix to obtain the fault voltage matrix of the distribution network.

[0177] The result output unit 506 is used to calculate the fault electrical quantities of the distribution network based on the fault voltage matrix if the fault voltage matrix satisfies the fault calculation stability condition, and to use the fault electrical quantities as the fault information of the open-circuit grounding re-fault. The fault electrical quantities include node voltage, branch current and DG output current.

[0178] In one possible implementation, the modeling unit 502 is also used to obtain fault parameters in the network structure; based on the first node injection current matrix and the fault parameters, a second node injection current matrix of the fault component network is established; the first node injection current matrix, the second node injection current matrix and the positive and negative zero sequence impedance matrices are superimposed to obtain the first node voltage sequence component matrix of the fault component network.

[0179] In one possible implementation, the modeling unit 502 is also used to determine the single-phase disconnection node where the single-phase disconnection occurs; based on the positional relationship between the single-phase disconnection node and the power supply side of the distribution network, determine a node as a ground fault node from the single-phase disconnection nodes; obtain the grounding resistance corresponding to the ground fault node, and use the grounding resistance, the single-phase disconnection node, and the ground fault node as fault parameters.

[0180] In one possible implementation, the modeling unit 502 is also used to establish the third node voltage sequence component matrix of the normal component network based on the positive and negative zero-sequence impedance matrix and the first node injection current matrix; to obtain the impedance information of the fault node in the network structure based on the fault parameters; to determine the fault node positive sequence voltage of the fault node through the third node voltage sequence component matrix; to obtain the fault current vector based on the impedance information and the fault node positive sequence voltage through the preset boundary condition equations for single-phase open circuit faults and ground short circuit faults; and to establish the second node injection current matrix of the fault component network based on the fault current vector. The boundary condition equations characterize the equation relationship between the impedance information, the fault node positive sequence voltage, and the fault current vector.

[0181] In one possible implementation, the device further includes an impedance matrix construction unit for determining single-phase open-circuit nodes and ground short-circuit nodes in the network structure; obtaining branch impedance information between single-phase open-circuit nodes and ground short-circuit nodes; and obtaining the positive and negative zero-sequence impedance matrix of the network structure based on the branch impedance information.

[0182] In one possible implementation, the voltage sequence component correction unit 504 is further configured to obtain the grid connection point positive sequence voltage of the DG grid connection point in the first node voltage sequence component matrix; correct the DG positive sequence injection current in the first node injection current matrix based on the grid connection point positive sequence voltage to obtain the corrected DG positive sequence injection current; and correct the first node voltage sequence component matrix according to the corrected DG positive sequence injection current to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix.

[0183] In one possible implementation, the voltage sequence component correction unit 504 is further configured to update the first node injection current matrix based on the corrected positive sequence injection current of the DG to obtain the updated first node injection current matrix; based on the updated first node injection current matrix and the fault parameters in the network structure, to establish the updated second node injection current matrix of the fault component network; and to perform superposition calculation on the updated first node injection current matrix, the updated second node injection current matrix and the positive and negative zero sequence impedance matrices to obtain the second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix.

[0184] The distribution network fault calculation device with distributed power sources provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0185] Figure 6 A schematic diagram of the structure of the electronic device provided in this application. Figure 6 As shown, the electronic device 60 provided in this embodiment includes at least one processor 601 and a memory 602. Optionally, the device 60 further includes a communication component 603. The processor 601, memory 602, and communication component 603 are connected via a bus 604.

[0186] In a specific implementation, at least one processor 601 executes computer execution instructions stored in memory 602, causing at least one processor 601 to perform the above-described method.

[0187] The specific implementation process of processor 601 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0188] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0189] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0190] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0191] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0192] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0193] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0194] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0195] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0196] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0197] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0198] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0199] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0200] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for fault calculation of a power distribution network containing distributed power sources, characterized in that, The method comprises the following steps: in response to monitoring that a broken-line grounding fault occurs in the power distribution network, obtaining a first node injection current matrix of a normal component network in the power distribution network; based on a positive and negative zero sequence impedance matrix of a network structure corresponding to the power distribution network and the first node injection current matrix, establishing a first node voltage sequence component matrix of a fault component network in the power distribution network; according to a positive sequence voltage of the distributed power supply grid connection point in the first node voltage sequence component matrix, correcting DG positive sequence injection current in the first node injection current matrix to obtain corrected DG positive sequence injection current; according to the corrected DG positive sequence injection current, correcting the first node voltage sequence component matrix to obtain a second node voltage sequence component matrix; performing weighted processing on the first node voltage sequence component matrix and the second node voltage sequence component matrix to obtain a fault voltage matrix of the power distribution network; if the fault voltage matrix satisfies a fault calculation stability condition, calculating a fault electrical quantity of the power distribution network according to the fault voltage matrix, and taking the fault electrical quantity as fault information of the broken-line grounding fault, wherein the fault electrical quantity comprises node voltage, branch current and DG output current.

2. The method of claim 1, wherein, The method comprises the following steps: obtaining fault parameters in the network structure; based on the first node injection current matrix and the fault parameters, establishing a second node injection current matrix of the fault component network; performing superposition calculation on the first node injection current matrix, the second node injection current matrix and the positive and negative zero sequence impedance matrix to obtain the first node voltage sequence component matrix of the fault component network.

3. The method of claim 2, wherein, The method comprises the following steps: determining a single-phase broken-line node where single-phase broken line occurs; based on a positional relationship between the single-phase broken-line node and a power supply side of the power distribution network, determining a node as a ground short-circuit node from the single-phase broken-line node; obtaining a ground resistance corresponding to the ground short-circuit node, and taking the ground resistance, the single-phase broken-line node and the ground short-circuit node as fault parameters.

4. The method according to claim 2, characterized in that, The method comprises the following steps: based on the positive and negative zero sequence impedance matrix and the first node injection current matrix, establishing a third node voltage sequence component matrix of the normal component network; based on the fault parameters, obtaining impedance information of the fault node in the network structure; determining a fault node positive sequence voltage of the fault node through the third node voltage sequence component matrix; based on the impedance information and the fault node positive sequence voltage, obtaining a fault current vector through a preset boundary condition equation of single-phase broken-line fault and ground short-circuit fault; based on the fault current vector, establishing the second node injection current matrix of the fault component network; The boundary condition equation represents an equation relationship between the impedance information, the fault node positive sequence voltage and the fault current vector.

5. The method according to any one of claims 1 to 4, characterized in that, The positive and zero sequence impedance matrix of the network structure is constructed, including: Determine the single-phase broken line node and the ground short circuit node in the network structure; Obtain the branch impedance information between the single-phase broken line node and the ground short circuit node; Based on the branch impedance information, obtain the positive and zero sequence impedance matrix of the network structure.

6. The method according to any one of claims 1 to 4, characterized in that, The first node voltage sequence component matrix is modified according to the modified DG positive sequence injection current, and a second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix is obtained. The DG grid-connected point positive sequence voltage in the first node voltage sequence component matrix is obtained. The DG positive sequence injection current in the first node injection current matrix is modified based on the grid-connected point positive sequence voltage, and a modified DG positive sequence injection current is obtained. The first node voltage sequence component matrix is modified according to the modified DG positive sequence injection current, and a second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix is obtained.

7. The method of claim 6, wherein, The first node injection current matrix is updated according to the modified DG positive sequence injection current, and an updated first node injection current matrix is obtained. Based on the updated first node injection current matrix and the fault parameters in the network structure, an updated second node injection current matrix of the fault component network is established. The updated first node injection current matrix, the updated second node injection current matrix and the positive and zero sequence impedance matrix are superimposed to obtain a second node voltage sequence component matrix corresponding to the first node voltage sequence component matrix. It comprises 8. A power distribution network fault calculation apparatus containing distributed power sources, characterized by, A fault response unit is configured to, in response to monitoring that a broken line grounding complex fault occurs in the power distribution network, acquire a first node injection current matrix of a normal component network in the power distribution network; A modeling unit is configured to, based on a positive and zero sequence impedance matrix of a network structure corresponding to the power distribution network and the first node injection current matrix, establish a first node voltage sequence component matrix of a fault component network in the power distribution network; A DG injection current correction unit is configured to, according to a positive sequence voltage of a distributed power grid-connected point in the power distribution network in the first node voltage sequence component matrix, correct a DG positive sequence injection current in the first node injection current matrix to obtain a modified DG positive sequence injection current; A voltage sequence component correction unit is configured to, according to the modified DG positive sequence injection current, modify the first node voltage sequence component matrix to obtain a second node voltage sequence component matrix; A synthesis unit is configured to perform weighting processing on the first node voltage sequence component matrix and the second node voltage sequence component matrix to obtain a fault voltage matrix of the power distribution network. ​ The result output unit is configured to, if the fault voltage matrix satisfies a fault calculation stability condition, calculate a fault electrical quantity of the power distribution network according to the fault voltage matrix, and take the fault electrical quantity as fault information of the broken-line-to-ground compound fault, wherein the fault electrical quantity includes node voltage, branch current and DG output current.

9. An electronic device, comprising: The method comprises: one or more processors; a storage device configured to store one or more programs, which, when executed by the one or more processors, cause the electronic device to implement the method for fault calculation of a power distribution network with distributed power supply according to any one of claims 1 to 7.

10. A computer readable storage medium characterized by The computer readable storage medium stores computer execution instructions, and the computer execution instructions are executed by the processor to implement the method for fault calculation of a power distribution network with distributed power supply according to any one of claims 1 to 7.

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