Reliability evaluation method and system for multi-power-supply radiation type power grid

Abstract

The invention provides a reliability evaluation method and system for a multi-power-supply radiation type power grid, and the method comprises the steps: generating a partition branch current node injection matrix and a partition node current branch injection matrix, and outputting an isolation node matrix; enabling multiple power supplies to be equivalent to common nodes, and generating an undirected graph adjacency matrix of the power grid; determining connectivity between power grid nodes in each fault scene to obtain a branch fault node connectivity matrix; updating the load classification matrix; determining a corresponding load classification matrix, determining a power supply branch fault node connectivity matrix and a standby power supply branch fault node connectivity matrix in combination with a corresponding priority strategy, and updating parameters of the load classification matrix; and calculating a node reliability index and a system reliability index according to the updated load classification matrix, and evaluating the reliability of the power grid. The method considers the cascading failure of the power grid and the influence of the cascading failure on multiple power supplies, and can accurately and quickly evaluate the reliability of the multi-power-supply radiation type power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of reliability assessment of power grids, and in particular to a reliability assessment method and system for a radial power grid with multiple power sources. Background Art

[0002] Existing technical solutions for multi-power grid reliability assessment use an extended minimum path search method for each load point to complete backup and extended minimum path searches, obtaining all minimum paths for the load point. The minimum path matrix method is then used to generate first-order, second-order, and third-order original minimum cut sets, distinguishing between the main supply branches and interconnecting branches within all minimum paths. The common-mode associated device replacement method is used to replace equipment in the main supply branches to generate common-mode minimum cut sets. Switchable minimum cut sets are generated based on the common-mode minimum cut sets and the original minimum cut sets, and the reliability parameters of the switchable minimum cut sets are calculated. The parameters of the original minimum cut sets and the common-mode minimum cut sets are calculated to obtain a reliability index for each load point. The reliability index of each load point is then calculated to obtain a system reliability index. This existing solution is essentially a solution for grid reliability assessment in a primary power + backup power scenario. It does not consider the simultaneous power supply of multiple power sources or the ability of multiple power sources to restore power to isolated nodes in the event of a cascading failure. Summary of the Invention

[0003] The purpose of the present invention is to propose a reliability assessment method and system for a radial power grid with multiple power sources, so as to solve the technical problems of achieving simultaneous power supply of multiple power sources and the ability of multiple power sources to restore power supply to isolated nodes under cascading failures.

[0004] In one aspect, a reliability assessment method for a radial power grid with multiple power sources is provided, comprising:

[0005] generating a partitioned branch current node injection matrix and a partitioned node current branch injection matrix based on the obtained network matrix, and outputting the partitioned node current branch injection matrix as an isolation node matrix; the partitioned branch current node injection matrix indicates which branches can be isolated from the faulty portion of the main feeder by switches when a main feeder fails; and the partitioned node current branch injection matrix indicates which nodes can be isolated from the faulty area when a branch fails;

[0006] Equivalently treating multiple power sources as common nodes, and generating an undirected graph adjacency matrix of the power grid through the equivalent common nodes; determining the connectivity between the power grid nodes under each fault scenario based on the undirected graph adjacency matrix to obtain a branch fault node connectivity matrix; and updating the load classification matrix based on the branch fault node connectivity matrix; the undirected graph adjacency matrix indicates whether the nodes corresponding to the rows and columns are connected;

[0007] Determine a corresponding load classification matrix based on the network matrix, and determine a power branch fault node connectivity matrix and a backup power branch fault node connectivity matrix based on the load classification matrix and the corresponding priority strategy; update the parameters of the load classification matrix based on the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix; the load classification matrix indicates whether the corresponding power grid node is in the fault area and whether it can be restored through the backup line / connector switch / backup power supply / main power supply when a branch fault occurs;

[0008] The corresponding node reliability index is calculated according to the updated load classification matrix, and the corresponding system reliability index is determined according to the node reliability index; and the grid reliability is evaluated according to the system reliability index.

[0009] Preferably, generating a partitioned branch current node injection matrix and a partitioned node current branch injection matrix includes:

[0010] The grid node current injection information and branch current information are determined based on the network matrix. The branches are set as row information and the columns are set as node information. Corresponding parameters are used to indicate which branches can be isolated from the faulty part of the main feeder by switches. The corresponding partitioned branch current node injection matrix is ​​generated. The branch current node injection matrix is ​​then inverted to obtain the partitioned node current branch injection matrix.

[0011] Preferably, the undirected graph adjacency matrix includes,

[0012] The rows and columns of the matrix are set to the numbers of the corresponding nodes, and the corresponding parameter values ​​are set to the first parameter or the second parameter, where the first parameter indicates that there is a branch between the nodes of the corresponding row and column, and the second parameter indicates that there is no branch between the nodes of the corresponding row and column.

[0013] Preferably, determining the connectivity between the power grid nodes in each fault scenario according to the undirected graph adjacency matrix includes:

[0014] sequentially detecting faulty branches in the faulty region of the isolated node matrix, and replacing corresponding faulty branch values ​​in the undirected graph adjacency matrix with corresponding second parameters to obtain a fault adjacency matrix;

[0015] The connectivity parameter between all nodes in the fault adjacency matrix and themselves is set as the first parameter to obtain the branch fault node connectivity matrix.

[0016] Preferably, the determining of the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix based on the load classification matrix in combination with the corresponding priority strategy includes:

[0017] The priority strategy is set to restore the connection with the main power supply through the tie switch first, and the connectivity matrix of the power branch fault node is determined in combination with the tie branch corresponding to the tie switch in the load classification matrix.

[0018] Preferably, the method of determining the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix based on the load classification matrix in combination with the corresponding priority strategy further includes:

[0019] The priority strategy is set to prioritize recovery through the backup power supply, and the backup power supply node connectivity matrix of the backup power supply branch fault node is determined by combining the tie branches corresponding to the tie switches in the load classification matrix with the backup power supply nodes.

[0020] Preferably, the node reliability index corresponding to the calculation includes:

[0021] Determine a failure mode and outage time matrix based on the network matrix, wherein the failure mode and outage time matrix is ​​used to calculate the node outage time, wherein the first element in the failure mode and outage time matrix represents the switching time of the corresponding branch, the second element represents the switching time of the corresponding branch and the switching time of the transfer line, and the third element represents the maintenance time of the corresponding branch;

[0022] The corresponding reliability index is determined according to the failure rate and failure mode of each node in the load classification matrix and the outage time matrix. The reliability index at least includes the outage time of the node and the average power outage time of the node.

[0023] Preferably, the determining of the corresponding system reliability index includes:

[0024] Obtain the number of users under the node and the rated power of the load under the node, and determine the corresponding system reliability index in combination with the node reliability index; the system reliability index at least includes the average power outage duration of the system, the average power outage rate of the system, the average power outage duration of users, the average power supply availability rate, the average power supply unavailability rate, the power shortage index and the average power shortage index.

[0025] On the other hand, a reliability assessment system for a radial power grid with multiple power sources is provided to implement the reliability assessment method for a radial power grid with multiple power sources, comprising:

[0026] A first matrix generation module is configured to generate a partitioned branch current node injection matrix and a partitioned node current branch injection matrix based on the acquired network matrix, and output the partitioned node current branch injection matrix as an isolation node matrix; the partitioned branch current node injection matrix indicates which branches can be isolated from the faulty portion of the main feeder by switches when a main feeder fails; and the partitioned node current branch injection matrix indicates which nodes can be isolated from the faulty area when a branch fails;

[0027] An equivalent module is configured to treat multiple power sources as equivalent common nodes and generate an undirected graph adjacency matrix of the power grid using the equivalent common nodes; determine the connectivity between the power grid nodes under each fault scenario based on the undirected graph adjacency matrix to obtain a branch fault node connectivity matrix; and update the load classification matrix based on the branch fault node connectivity matrix; the undirected graph adjacency matrix indicates whether the nodes corresponding to the rows and columns are connected;

[0028] A second matrix generation module is configured to determine a corresponding load classification matrix based on the network matrix, and determine a power branch fault node connectivity matrix and a backup power branch fault node connectivity matrix based on the load classification matrix in combination with a corresponding priority strategy; update parameters of the load classification matrix based on the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix; the load classification matrix indicates whether the corresponding power grid node is in a fault zone and whether it can be restored through a backup line / tie switch / backup power supply / main power supply when a branch fault occurs;

[0029] The evaluation module is used to calculate the corresponding node reliability index according to the updated load classification matrix, determine the corresponding system reliability index according to the node reliability index; and evaluate the reliability of the power grid according to the system reliability index.

[0030] In summary, the implementation of the embodiments of the present invention has the following beneficial effects:

[0031] The reliability assessment method and system for a radial power grid with multiple power sources provided by the present invention take into account grid cascading failures and their impact on multiple power sources, calculate the effect of multiple power sources in restoring power to nodes in non-fault areas, and can accurately and quickly assess the reliability of a radial power grid with multiple power sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0033] Figure 1 1 is a schematic diagram of the main process of a reliability assessment method for a radial power grid with multiple power sources in an embodiment of the present invention.

[0034] Figure 2 Schematic diagram of a typical radial distribution network with 8 nodes in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0036] like Figure 1 FIG. 1 is a schematic diagram of an embodiment of a reliability assessment method for a radial power grid with multiple power sources provided by the present invention. In this embodiment, the method includes the following steps:

[0037] Step S1: generating a partitioned branch current node injection matrix and a partitioned node current branch injection matrix based on the acquired network matrix, and outputting the partitioned node current branch injection matrix as an isolation node matrix; the partitioned branch current node injection matrix indicates which branches can be isolated from the faulty portion of the main feeder by switches when a main feeder fails; and the partitioned node current branch injection matrix indicates which nodes can be isolated from the faulty area when a branch fails;

[0038] Specific embodiments are as follows Figure 2 Taking the node system shown as an example, node 0 and node 8 are power nodes.

[0039] Input data according to the network matrix, where the input data definition includes:

[0040] Network matrix ND: one row is various types of information of one branch, and one column is a certain type of information;

[0041] Column 0 is the branch number;

[0042] The first column is the node number of the branch head end;

[0043] The second column is the branch end node number;

[0044] Column 3 contains information on the type of branch circuit protection device (0: no protection or switching device, 1: circuit breaker, 2: switch, 3: fuse);

[0045] The fourth column is the probability q that the protection device fails (operates unsuccessfully) i , where i is the branch number;

[0046] Column 5 is the branch failure rate;

[0047] · Column 6 is the branch line maintenance time;

[0048] Column 7 is the branch recovery (switch switching) time.

[0049]

[0050] The only load node is node 7, with 1 load user and a rated load power of 5MW.

[0051] Step S2: Equivalent multiple power sources to common nodes, and generating an undirected graph adjacency matrix of the power grid through the equivalent common nodes; determining the connectivity between the power grid nodes under each fault scenario based on the undirected graph adjacency matrix to obtain a branch fault node connectivity matrix; and updating the load classification matrix based on the branch fault node connectivity matrix; the undirected graph adjacency matrix indicates whether the nodes corresponding to the rows and columns are connected;

[0052] In a specific embodiment, the generation of the partitioned branch current node injection matrix and the partitioned node current branch injection matrix includes determining the grid node current injection information and the branch current information according to the network matrix, setting the branch as row information and the column as node information, indicating which branches can be isolated by switches and fault parts in the main feeder through corresponding parameters, and generating the corresponding partitioned branch current node injection matrix; and inverting the branch current node injection matrix to obtain the partitioned node current branch injection matrix.

[0053] Without considering the power nodes, a zone branch current to bus injection matrix (ZBIBC) is constructed to partition branch faults and identify which branches can be isolated from the faulted portion of the main feeder by switches. The ZBIBC matrix consists of branches and columns, nodes.

[0054]

[0055]

[0056] The ZBIBC matrix is ​​inverted to obtain the zone bus injection to branch current matrix ZBIBC (Zone Bus Injection To Branch Current Matrix).

[0057] ZBIBC=ZBCBI -1

[0058]

[0059] Assume that all protection devices are automatic and completely reliable, that is, let the protection failure probability q of the protection branch in the ND matrix be i 0; and it is assumed that there is no protection element upstream. Calculate the failure mode and influence coefficient matrix FMECM based on ZBIBC s1 The Failure Mode and Effect Coefficient Matrix (FMEC) describes the impact of a line fault on upstream devices. For line i containing a circuit breaker and fuse, all 0s and 1s in the corresponding row remain unchanged. For line j without protection, all 1s in that row remain in place.

[0060]

[0061] Update FMECM to take into account the impact of upstream protection components s1 For FMECM s2 , describes the response of upstream protection to line faults. First, according to FMECM s1 And ZBIBC, find a path from the power node to branch i, all protections on this path will respond to the fault on branch i. If there is a reliable protection on the path, the fault on branch i can be effectively isolated; if there is a reliable protection on the path with probability q i If the protection fails, the fault on branch i is considered as the case where all protection on the path fails. s2 Each element e ij Equal to FMECM s1 The product of all elements in the j-th column of that belong to the path from the i-th branch to the source. s2 The specific generation steps are as follows:

[0062] 1) Perform outer loop for all branches: Select line i and let R b is the end node of line i, m is a row vector whose elements are all 1, and the vector dimension is 1×n b , n b is the total number of branches.

[0063] 2) Perform inner loop on all branches and select branch j. If ZBIBC(j,R b )=1, indicating that branch j is at node R b , so branch j affects the power supply status of the node.

[0064]

[0065] in This loop accumulates all upstream protections that affect the end node of the branch. After the inner loop is completed, let

[0066] FMECM s2 (i, all columns) = m

[0067] FMECM can accumulate the effects of protection device failures upstream.

[0068] Let the isolated node matrix ILM (Isolated Load Matrix) equal to FMECM s2 The 0 element in the matrix indicates that when the corresponding row branch fails, the corresponding column node can be isolated from the fault area.

[0069] ILM=FMECM s2

[0070]

[0071] Step S3: determining a corresponding load classification matrix based on the network matrix, and determining a power branch fault node connectivity matrix and a backup power branch fault node connectivity matrix based on the load classification matrix and the corresponding priority strategy; updating parameters of the load classification matrix based on the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix; the load classification matrix indicates whether the corresponding power grid node is in the fault zone and whether it can be restored through the backup line / tie switch / backup power supply / main power supply when a branch fault occurs;

[0072] In a specific embodiment, the undirected graph adjacency matrix includes setting the rows and columns of the matrix to the numbers of the corresponding nodes, and setting the corresponding parameter values ​​to the first parameter or the second parameter, wherein the first parameter indicates that there is a branch between the nodes of the corresponding row and column, and the second parameter indicates that there is no branch between the nodes of the corresponding row and column.

[0073] The method of determining the connectivity between the power grid nodes in each fault scenario based on the undirected graph adjacency matrix includes sequentially detecting the fault branches in the fault area of ​​the isolated node matrix, and replacing the corresponding fault branch values ​​in the undirected graph adjacency matrix with the corresponding second parameter to obtain a fault adjacency matrix; and setting the connectivity parameters between all nodes in the fault adjacency matrix and themselves to the first parameter to obtain a branch fault node connectivity matrix.

[0074] First, based on the input data ND, the (multiple) power sources are treated as common nodes, and the undirected graph adjacency matrix AM (Adjacency Matrix) of the power grid is constructed. The rows and columns of the matrix correspond to node numbers. If AM(i,j) = 1, it indicates that a branch exists between nodes i and j, and the two nodes are connected.

[0075]

[0076] Traverse the fault area and calculate the connectivity between grid nodes under each fault scenario, as follows:

[0077] 1) Traverse the fault region of the ILM matrix and construct the fault adjacency matrix (FAM) based on the AM. The specific method is to traverse the fault branches in the fault region and replace the corresponding fault branch values ​​in the AM with 0.

[0078] 2) Traverse the FAM and use the Floyd-Warshall algorithm to calculate internode connectivity and construct a three-dimensional branch fault node connectivity matrix (BFNCM). The i dimension of the BFNCM represents the fault branch, while the j and k dimensions represent nodes. The j and k dimensions have the same meaning as the AM. The Floyd-Warshall algorithm formula is as follows:

[0079] (i) Initialize the connectivity matrix

[0080] C[i][j]=FAM

[0081] C[i][i]=1

[0082] That is, the connectivity from itself to itself is 1

[0083] (ii) For each intermediate node k, update the connectivity of all node pairs (i, j):

[0084] C[i][j]=C[i][j]∨(C[i][k]∧C[k][j])

[0085] (iii) Update repeatedly until all nodes are traversed.

[0086] Calculate the connectivity between nodes and multiple power supplies: Slice the three-dimensional BFNCM based on the power node number (0 in this case) to form the power-branch fault node connectivity (two-dimensional) matrix POWER_BFNCM (PowerBranch Fault Node Connectivity Matrix).

[0087] POWER_BFNCM=BFNCM[:,powernodes,∶]

[0088]

[0089] The method of determining the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix based on the load classification matrix and the corresponding priority strategy includes:

[0090] The priority strategy is set to prioritize restoring the connection to the main power source through the tie switch, and the connectivity matrix of the power branch fault node is determined by combining the tie branch corresponding to the tie switch in the load classification matrix. The priority strategy is set to prioritize restoring the connection through the backup power source, and the connectivity matrix of the backup power branch fault node is determined by combining the tie branch corresponding to the tie switch in the load classification matrix and the backup power node.

[0091] Let the load classification matrix LTM (Load Type Matrix) be equal to POWER_BFNCM.

[0092] LTM=POWER_BFNCM

[0093] Prioritize restoring the connection to the main power source through the tie switch: Repeat the second stage, considering the tie switch forming a tie branch. Calculate the two-dimensional power-branch fault node connectivity matrix, TL_BFNCM (Tie Line-Branch Fault Node Connectivity Matrix), and update the LTM. For the existing LTM, find the coordinates of the same position where the LTM and Power_BFNCM have the same value, LTM = 1, TL_BFNCM = 0, and replace the value of this coordinate in the LTM with 3.

[0094] LTM[(LTM==1)&(TL_BFNCM==0)]=3

[0095] Second, restore the backup power supply: Considering the tie switch forming the tie branch and the backup power supply node, calculate the backup power supply-branch fault node connectivity matrix (BK_BFNCM) (two-dimensional) and update the LTM. For the existing LTM, find the coordinates where the LTM and Power_BFNCM have the same value (LTM=1, BK_BFNCM=0) and replace the value of this coordinate in the LTM with 4.

[0096] LTM[(LTM==1)&(BK_BFNCM==0)]=4

[0097] At this time, the node value type in the LTM is: 0 fault requires repair, 1 through the main power supply recovery, 3 priority through the tie line and the main power supply recovery, 4 secondly through the backup power supply (or with the tie line) recovery.

[0098]

[0099] Modify the LTM element: if the element is 1, 3 or 4, it is the switching / switching time of the corresponding branch; if the element is 0, it is the maintenance time of the corresponding branch.

[0100] Step S4, calculating the corresponding node reliability index according to the updated load classification matrix, determining the corresponding system reliability index according to the node reliability index; and evaluating the reliability of the power grid according to the system reliability index.

[0101] In a specific embodiment, the calculation of the corresponding node reliability index includes determining a failure mode and outage time matrix based on a network matrix, wherein the failure mode and outage time matrix is ​​used to calculate the node outage time, wherein the first element in the failure mode and outage time matrix represents the switching time of the corresponding branch, the second element represents the switching time of the corresponding branch and the switching time of the transfer line, and the third element represents the maintenance time of the corresponding branch; and determining the corresponding reliability index based on the failure rate of each node in the load classification matrix and the failure mode and outage time matrix, wherein the reliability index includes at least the outage time of the node and the average power outage time of the node.

[0102] Construct the failure mode and downtime matrix FMITM to calculate the node downtime.

[0103] FMITM initial =LTM

[0104] FMITM initial The element is modified: if the element is 0, it is the switching time of the corresponding branch; if the element is 1, it is the switching time of the corresponding branch and the switching time of the transfer line; if the element is 2, it is the maintenance time of the corresponding branch.

[0105] Calculate the final FMITM

[0106]

[0107] Computing node reliability indicators

[0108] The failure rate index of a node is calculated as:

[0109] λ bus =FMECM s2 T λ branch

[0110] Among them, λ branch is the failure rate of each branch (ND column 5).

[0111] The node downtime is:

[0112] U bus =FMITM T λ branch

[0113] Average power outage time of nodes (hours):

[0114] r i =U i / λ i .

[0115] Determining the corresponding system reliability index includes obtaining the number of users under the node and the rated power of the load under the node, and determining the corresponding system reliability index in combination with the node reliability index; the system reliability index includes at least the average power outage duration of the system, the average power outage rate of the system, the average power outage duration of users, the average power supply availability rate, the average power supply unavailability rate, the power shortage index and the average power shortage index.

[0116] The system reliability index is calculated as follows. Where, N i is the number of users under the node, P i is the rated power of the load under the node, both are input data

[0117] 1) System Average Interruption Duration (SAIDI)

[0118]

[0119] 2) System Average Interruption Rate (SAIFI)

[0120]

[0121] 3) Average power outage duration for customers (CAIDI)

[0122]

[0123] 4) Average Supply Availability Index (ASAI)

[0124]

[0125] 5) Average Supply Unavailability (ASUI)

[0126] ASUI=1-ASAI

[0127] 6) Energy Insufficient Status (EENS)

[0128]

[0129] 7) Average Energy Insufficiency Score (AENS)

[0130]

[0131] An embodiment of the present invention further provides a reliability assessment system for a radial power grid with multiple power sources, for implementing the reliability assessment method for a radial power grid with multiple power sources, comprising:

[0132] A first matrix generation module is configured to generate a partitioned branch current node injection matrix and a partitioned node current branch injection matrix based on the acquired network matrix, and output the partitioned node current branch injection matrix as an isolation node matrix; the partitioned branch current node injection matrix indicates which branches can be isolated from the faulty portion of the main feeder by switches when a main feeder fails; and the partitioned node current branch injection matrix indicates which nodes can be isolated from the faulty area when a branch fails;

[0133] An equivalent module is configured to treat multiple power sources as equivalent common nodes and generate an undirected graph adjacency matrix of the power grid using the equivalent common nodes; determine the connectivity between the power grid nodes under each fault scenario based on the undirected graph adjacency matrix to obtain a branch fault node connectivity matrix; and update the load classification matrix based on the branch fault node connectivity matrix; the undirected graph adjacency matrix indicates whether the nodes corresponding to the rows and columns are connected;

[0134] A second matrix generation module is configured to determine a corresponding load classification matrix based on the network matrix, and determine a power branch fault node connectivity matrix and a backup power branch fault node connectivity matrix based on the load classification matrix in combination with a corresponding priority strategy; update parameters of the load classification matrix based on the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix; the load classification matrix indicates whether the corresponding power grid node is in a fault zone and whether it can be restored through a backup line / tie switch / backup power supply / main power supply when a branch fault occurs;

[0135] The evaluation module is used to calculate the corresponding node reliability index according to the updated load classification matrix, determine the corresponding system reliability index according to the node reliability index; and evaluate the reliability of the power grid according to the system reliability index.

[0136] It should be noted that the system described in the above embodiment corresponds to the method described in the above embodiment. Therefore, the parts of the system described in the above embodiment that are not described in detail can be obtained by referring to the contents of the method described in the above embodiment, and will not be repeated here.

[0137] In summary, the implementation of the embodiments of the present invention has the following beneficial effects:

[0138] The reliability assessment method and system for a radial power grid with multiple power sources provided by the present invention take into account grid cascading failures and their impact on multiple power sources, calculate the effect of multiple power sources in restoring power to nodes in non-fault areas, and can accurately and quickly assess the reliability of a radial power grid with multiple power sources.

[0139] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A reliability assessment method for a radial power grid with multiple power sources, characterized in that: include: generating a partitioned branch current node injection matrix and a partitioned node current branch injection matrix according to the obtained network matrix, and outputting the partitioned node current branch injection matrix as an isolated node matrix; The partitioned branch current node injection matrix indicates which branches can be isolated from the faulty part of the main feeder by switches when the main feeder fails; The partition node current branch injection matrix indicates which nodes can be isolated from the fault area when a branch fails; Equivalently treating multiple power sources as common nodes, and generating an undirected graph adjacency matrix of the power grid through the equivalent common nodes; determining the connectivity between power grid nodes under each fault scenario based on the undirected graph adjacency matrix, and obtaining a branch fault node connectivity matrix; and updating the load classification matrix according to the branch fault node connectivity matrix; the undirected graph adjacency matrix indicates whether the nodes corresponding to the rows and columns are connected; Determine a corresponding load classification matrix according to the network matrix, and determine a power branch fault node connectivity matrix and a backup power branch fault node connectivity matrix based on the load classification matrix and a corresponding priority strategy; Updating the parameters of the load classification matrix according to the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix; The load classification matrix indicates whether the corresponding grid node is in the fault area and whether it can be restored through the backup line / connector switch / backup power supply / main power supply when a branch fault occurs; The corresponding node reliability index is calculated according to the updated load classification matrix, and the corresponding system reliability index is determined according to the node reliability index; and the grid reliability is evaluated according to the system reliability index.

2. The method according to claim 1, wherein The generating of the partitioned branch current node injection matrix and the partitioned node current branch injection matrix includes: Determine grid node current injection information and branch current information based on the network matrix, set the branch as row information and the column as node information, use corresponding parameters to indicate which branches can be isolated from the fault part in the main feeder by switches, and generate the corresponding partition branch current node injection matrix; The branch current node injection matrix is ​​inverted to obtain the partition node current branch injection matrix.

3. The method according to claim 2, wherein The undirected graph adjacency matrix includes, The rows and columns of the matrix are set to the numbers of the corresponding nodes, and the corresponding parameter values ​​are set to the first parameter or the second parameter, where the first parameter indicates that there is a branch between the nodes of the corresponding row and column, and the second parameter indicates that there is no branch between the nodes of the corresponding row and column.

4. The method according to claim 3, wherein Determining the connectivity between the power grid nodes in each fault scenario according to the undirected graph adjacency matrix includes: sequentially detecting faulty branches in the faulty region of the isolated node matrix, and replacing corresponding faulty branch values ​​in the undirected graph adjacency matrix with corresponding second parameters to obtain a fault adjacency matrix; The connectivity parameter between all nodes in the fault adjacency matrix and themselves is set as the first parameter to obtain the branch fault node connectivity matrix.

5. The method according to claim 4, wherein The method of determining the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix based on the load classification matrix and the corresponding priority strategy includes: The priority strategy is set to restore the connection with the main power supply through the tie switch first, and the connectivity matrix of the power branch fault node is determined in combination with the tie branch corresponding to the tie switch in the load classification matrix.

6. The method according to claim 5, wherein The method of determining the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix based on the load classification matrix in combination with the corresponding priority strategy also includes: The priority strategy is set to prioritize recovery through the backup power supply, and the backup power supply node connectivity matrix of the backup power supply branch fault node is determined by combining the tie branches corresponding to the tie switches in the load classification matrix with the backup power supply nodes.

7. The method according to claim 6, wherein The node reliability index corresponding to the calculation includes: Determine a failure mode and outage time matrix based on the network matrix, wherein the failure mode and outage time matrix is ​​used to calculate the node outage time, wherein the first element in the failure mode and outage time matrix represents the switching time of the corresponding branch, the second element represents the switching time of the corresponding branch and the switching time of the transfer line, and the third element represents the maintenance time of the corresponding branch; The corresponding reliability index is determined according to the failure rate and failure mode of each node in the load classification matrix and the outage time matrix. The reliability index at least includes the outage time of the node and the average power outage time of the node.

8. The method according to claim 7, wherein The determining of the corresponding system reliability index includes: Obtain the number of users under the node and the rated power of the load under the node, and determine the corresponding system reliability index in combination with the node reliability index; the system reliability index at least includes the average power outage duration of the system, the average power outage rate of the system, the average power outage duration of users, the average power supply availability rate, the average power supply unavailability rate, the power shortage index and the average power shortage index.

9. A reliability assessment system for a radial power grid with multiple power sources, for implementing the method according to any one of claims 1 to 8, characterized in that: include, a first matrix generation module, configured to generate a partitioned branch current node injection matrix and a partitioned node current branch injection matrix according to the acquired network matrix, and output the partitioned node current branch injection matrix as an isolation node matrix; The partitioned branch current node injection matrix indicates which branches can be isolated from the faulty part of the main feeder by switches when the main feeder fails; The partition node current branch injection matrix indicates which nodes can be isolated from the fault area when a branch fails; The equivalent module is used to equate multiple power sources to common nodes and generate an undirected graph adjacency matrix of the power grid through the equivalent common nodes; the connectivity between the power grid nodes under each fault scenario is determined based on the undirected graph adjacency matrix to obtain the branch fault node connectivity matrix; and updating the load classification matrix according to the branch fault node connectivity matrix; the undirected graph adjacency matrix indicates whether the nodes corresponding to the rows and columns are connected; A second matrix generation module is used to determine a corresponding load classification matrix according to the network matrix, and determine a power branch fault node connectivity matrix and a backup power branch fault node connectivity matrix based on the load classification matrix and a corresponding priority strategy; Updating the parameters of the load classification matrix according to the power branch fault node connectivity matrix and the backup power branch fault node connectivity matrix; The load classification matrix indicates whether the corresponding grid node is in the fault area and whether it can be restored through the backup line / connector switch / backup power supply / main power supply when a branch fault occurs; The evaluation module is used to calculate the corresponding node reliability index according to the updated load classification matrix, determine the corresponding system reliability index according to the node reliability index; and evaluate the reliability of the power grid according to the system reliability index.

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