Load recovery evaluation method, system, device and medium for ac-dc distribution network

Abstract

The application discloses a load recovery evaluation method, system, equipment and medium of an AC-DC distribution network, and is characterized in that the method comprises the following steps: obtaining network topology data and converter operation data of the AC-DC hybrid distribution network; determining normal power supply paths according to the network topology data, simulating faults on each branch to determine fault branches, and judging whether each normal power supply path contains each fault branch; if yes, determining the power consumption nodes corresponding to the normal power supply paths as load nodes that need to be transferred; searching for transfer paths for the load nodes that need to be transferred respectively, calculating the newly added transmission power of each transfer path according to the power consumption data corresponding to the transfer paths, and calculating the load transfer amount under each fault scenario based on the newly added transmission power and the available transmission capacity of the converters passed by each transfer path; and evaluating the load recovery capability of the AC-DC distribution network based on the load transfer amount. The application can improve the accuracy of the judgment of the load recovery power supply situation of the AC-DC hybrid distribution network.

Description

Technical Field

[0001] This invention relates to the field of load transfer in distribution networks, and more particularly to load restoration assessment methods, systems, equipment, and media for AC / DC distribution networks. Background Technology

[0002] With the widespread integration of distributed power sources, DC loads, energy storage devices, and converters into distribution networks, hybrid AC / DC distribution networks are gradually becoming an important component of new power systems. Compared to traditional AC distribution networks, hybrid AC / DC distribution networks involve complex electrical connections between the AC network, DC network, and converters. When a branch line fails, some power-consuming nodes need to rely on backup power sources and alternative power supply paths to achieve load transfer, and the transmission capacity of the converter directly affects the power restoration effect after the fault. Therefore, it is necessary to analyze the load transfer process under fault scenarios to accurately determine the power restoration status of each power-consuming node.

[0003] Existing methods for analyzing distribution network faults mainly employ Monte Carlo simulation, fault mode and consequence analysis (FEMA), minimum path analysis, and fault traversal. These methods are largely geared towards traditional AC distribution network design. When analyzing load restoration after a fault, they typically rely solely on network connectivity to determine the existence of backup power paths, neglecting the impact of converter transmission capacity on load transfer capabilities in hybrid AC / DC distribution networks. When load transfer after a fault requires cross-regional power supply via converters, even if transfer paths exist, insufficient remaining converter transmission capacity may prevent the transfer of all loads. This leads to discrepancies between the restored power supply results and actual operating conditions, making it difficult to accurately reflect the load restoration capability after a fault. Summary of the Invention

[0004] This invention provides a method, system, equipment, and medium for assessing load restoration in AC / DC distribution networks, which can improve the accuracy of judging the load restoration status in AC / DC hybrid distribution networks under fault scenarios.

[0005] In a first aspect, embodiments of the present invention provide a load restoration assessment method for AC / DC distribution networks, comprising: The network topology data and converter operation data of the AC / DC hybrid distribution network are obtained. The network topology data includes power supply nodes, several branches, several power consumption nodes, and several converters. Based on the network topology data, determine the normal power supply path from all power consumption nodes to the power supply node, perform fault simulation on each branch to determine the faulty branch, and determine whether each normal power supply path contains each faulty branch. If so, determine the power consumption node corresponding to the normal power supply path as the load node that needs to be transferred. In the network topology data after removing the faulty branch, a transfer path connected to a preset backup power supply is searched for the load nodes that need to be transferred. Based on the power consumption data corresponding to the transfer path, the new transmission power of each transfer path is calculated. Based on the new transmission power and the available transmission capacity of the converters through which each transfer path passes, the load transfer amount under each fault scenario is calculated. The available transmission capacity is calculated based on the converter operation data. The load recovery capability of AC / DC distribution networks under different branch faults is evaluated based on the load transfer quantities described above.

[0006] This invention provides a complete data foundation for load transfer analysis under fault scenarios by acquiring network connection relationships and converter operating status information, thereby improving the accuracy of AC / DC hybrid distribution networks in judging load power restoration status under fault scenarios. By clarifying the power source and power supply path of each power consumption node under normal operating conditions, it provides a basis for fault impact range analysis, further improving the accuracy of AC / DC hybrid distribution networks in judging load power restoration status under fault scenarios. By simulating fault scenarios after each branch fails and identifying the load nodes requiring power transfer, it can accurately identify power consumption nodes that have lost normal power supply capacity due to the faulty branch, thereby improving the accuracy of fault impact range identification and thus improving the accuracy of AC / DC hybrid distribution networks in judging load power restoration status under fault scenarios. Furthermore, by removing the faulty branch… Searching for transfer paths between load nodes requiring power transfer and preset backup power sources in the subsequent network topology data allows for accurate identification of actual power restoration channels after a fault, thereby improving the accuracy of power restoration path analysis and ultimately enhancing the accuracy of load power restoration assessment in AC / DC hybrid distribution networks during fault scenarios. Calculating load transfer volume simultaneously considers both load transfer demand and converter transmission capacity constraints, avoiding errors arising from judging power restoration solely based on path connectivity, thus improving the accuracy of load power restoration assessment in AC / DC hybrid distribution networks during fault scenarios. Furthermore, determining the load power restoration status after a fault in the AC / DC distribution network accurately reflects the actual power restoration capabilities of each power-consuming node after the fault, further improving the accuracy of load power restoration assessment in AC / DC hybrid distribution networks during fault scenarios.

[0007] Furthermore, determining the normal power supply path from all power-consuming nodes to the power-supplying node based on the network topology data includes: Based on the network topology data, a node-branch association matrix is ​​constructed to characterize the connection status between each power-consuming node and each branch. The target matrix is ​​obtained by deleting the matrix column corresponding to the tie line data from the node branch association matrix. The target matrix is ​​then inverted to obtain the inversion result. The absolute value of each matrix element in the inversion result is taken to obtain the power supply path matrix. The network topology data includes the tie line data. Extract the branches that each power-consuming node passes through to the power supply node from the power supply path matrix, so as to determine the corresponding branches as the normal power supply path of each power-consuming node.

[0008] This invention improves the efficiency and accuracy of power supply path identification in complex AC / DC hybrid distribution networks by analyzing the power supply path relationship between each power consumption node and the power supply node in a matrix manner. This provides an accurate data foundation for subsequent fault impact analysis and load transfer calculation, thereby improving the accuracy of judging the load power restoration status in AC / DC hybrid distribution networks under fault scenarios.

[0009] Furthermore, in the network topology data after removing the faulty branch, searching for transfer paths connected to a preset backup power source for each of the load nodes requiring transfer includes: Extract the tie-line nodes connected to each of the load transfer nodes from the network topology data after removing the faulty branch. Starting from each of the aforementioned tie-line nodes, the system traces the electrical connections in the network topology data step by step until a preset backup power source is found, thus obtaining the transfer path corresponding to each of the aforementioned load nodes that need to be transferred.

[0010] This invention, through tracking the electrical connection between the load nodes requiring power transfer and the backup power source based on the network topology after a fault, accurately determines the feasible power transfer path corresponding to each load node, providing a reliable basis for subsequent load power restoration analysis, thereby improving the accuracy of judging the load power restoration status in AC / DC hybrid distribution networks under fault scenarios.

[0011] Furthermore, the step of calculating the additional transmission power for each of the power transfer paths based on the acquired power consumption data corresponding to the power transfer paths includes: Determine the set of target power-consuming nodes that will actually have their power restored on each of the aforementioned power transfer paths; The active power data corresponding to each target power node in the target power node set is read from the preset node load data table, and the active power data corresponding to the same transfer path are accumulated to calculate the new transmission power of the corresponding transfer path.

[0012] This invention, through statistical analysis of the active power data corresponding to the restored power load of each transfer path, accurately calculates the additional transmission power undertaken by the transfer path after a fault. This accurately reflects the power transmission demand during the transfer process, providing a reliable basis for subsequent power supply capacity verification, thereby improving the accuracy of judging the load restoration status in AC / DC hybrid distribution networks under fault scenarios.

[0013] Furthermore, the calculation of the load transfer amount under each fault scenario based on the newly added transmission power and the available transmission capacity of the converters through which each transfer path passes includes: Identify the converters included in each of the power transfer paths, and obtain the rated transmission capacity and current transmission power corresponding to each converter. Calculate the difference between the rated transmission capacity and the current transmission power to determine the available transmission capacity of each converter. The minimum value is selected from the available transmission capacity of each converter in the same power transfer path, and the minimum value is determined as the upper limit of the path transmission power of the corresponding power transfer path; The newly added transmission power is compared with the upper limit of the transmission power of each path. When the newly added transmission power is not greater than the upper limit of the transmission power of the path, the newly added transmission power is determined as the load transfer amount. When the newly added transmission power is greater than the upper limit of the transmission power of the path, the upper limit of the transmission power of the path is determined as the load transfer amount.

[0014] This invention verifies the additional transmission power by combining the available transmission capacity of the converter in the power transfer path, thereby achieving an accurate assessment of the recoverable power supply capacity after a fault. It can effectively identify the load transfer situation constrained by the converter capacity, thus improving the accuracy of judging the load power restoration status in AC / DC hybrid distribution networks under fault scenarios.

[0015] Furthermore, the assessment of the load recovery capability of the AC / DC distribution network under different branch faults based on the load transfer capacity includes: Based on the fault impact types recorded in the preset fault impact matrix and the load transfer amount under each fault scenario, the load transfer ratio corresponding to each power consumption node is calculated, and the power outage time corresponding to each power consumption node is determined based on the power outage time calculation rules corresponding to each load transfer ratio and each fault impact type. Obtain the failure rate corresponding to each fault branch under each of the aforementioned fault scenarios, and accumulate the aforementioned failure rates to calculate the number of power outages corresponding to each power consumption node. The power outage time of each power outage is multiplied by the active power data corresponding to each power consumption node to obtain the power shortage corresponding to each power consumption node. The load recovery capability assessment results of the AC / DC distribution network are determined based on the outage time, the number of outages, and the amount of power shortage.

[0016] This invention, by comprehensively considering factors such as fault impact type, load transfer capacity, outage time, number of outages, and power shortage, quantitatively evaluates the load restoration capacity under fault scenarios. It can comprehensively reflect the power restoration level of AC / DC distribution networks after branch faults, thereby improving the accuracy of judging the load restoration status of AC / DC hybrid distribution networks under fault scenarios.

[0017] Furthermore, the determination of the load recovery capability assessment result of the AC / DC distribution network based on the outage time, the number of outages, and the power shortage includes: calculating the system average outage time by performing a weighted average calculation of the outage time and the number of users corresponding to each power consumption node; calculating the system average outage frequency by performing a weighted average calculation of the number of outages and the number of users corresponding to each power consumption node; summing the power shortages to calculate the expected power shortage; and combining the system average outage time, the system average outage frequency, and the expected power shortage to obtain the load recovery capability assessment result of the AC / DC distribution network.

[0018] This invention achieves a unified quantitative expression of system-level reliability indicators by weighting and summing the outage time, number of outages, and power shortage amount for users and the entire network. This enables a comprehensive reflection of the load recovery capability of AC / DC distribution networks under the conditions of power transfer capacity and converter power constraints, thereby improving the accuracy and engineering applicability of the evaluation results.

[0019] Secondly, embodiments of the present invention provide a load recovery assessment system for a distribution network, the load recovery assessment system being used to perform the operation of the load recovery assessment method for AC / DC distribution networks as described in this application.

[0020] Thirdly, embodiments of the present invention provide a terminal device, including: a processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other through the communication bus; The memory is used to store at least one executable instruction that causes the processor to perform the operation of the load restoration assessment method for AC / DC distribution networks as described in this application.

[0021] Fourthly, embodiments of the present invention provide a computer-readable storage medium comprising a stored computer program, wherein, when the computer program is executed, it controls the device or system where the computer-readable storage medium is located to perform the load restoration assessment method for AC / DC distribution networks as described in this application.

[0022] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0023] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a flowchart illustrating one embodiment of the load restoration assessment method for AC / DC distribution networks provided in this application; Figure 2 This is a flowchart illustrating steps S201 to S203 provided in this application; Figure 3 This is a flowchart illustrating steps S301 to S303 provided in this application; Figure 4 This is a flowchart illustrating steps S401 to S404 provided in this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0027] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0030] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0031] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0032] With the integration of distributed power sources, DC loads, energy storage, and converters, hybrid AC / DC distribution networks exhibit strong coupling characteristics between AC, DC, and converters. After a fault occurs, some loads need to rely on backup power sources and transfer paths to restore power. Converter capacity plays a crucial role in constraining cross-regional power transfer capabilities. Existing methods are mostly based on topological connectivity or traditional fault simulation, primarily applicable to AC distribution networks, and do not consider converter transmission capacity limitations. This can lead to situations where paths are accessible in AC / DC transfer scenarios, but power restoration may not actually be possible, thus affecting the accurate assessment of load recovery capabilities.

[0033] See Figure 1In order to improve the accuracy of judging the load restoration status in AC / DC hybrid distribution networks under fault scenarios, an embodiment of the present invention provides a load restoration assessment method for AC / DC distribution networks, including steps S101 to S104. Step S101: Obtain network topology data and converter operation data of the AC / DC hybrid distribution network, wherein the network topology data includes power supply nodes, several branches, several power consumption nodes, and several converters. In some embodiments, electrical connection data between nodes in the distribution network are collected, and branches containing low-voltage distribution transformers are equivalently processed. The failure rate of the low-voltage distribution transformer is superimposed on the failure rate of its branch, and the transformer element is deleted, making it participate in topology modeling as an equivalent branch. Simultaneously, AC switches, DC switches, fuses, DC circuit breakers, and converters are uniformly abstracted as "special branches," and each of these special branches is specified to be connected to at least one load node at both ends, ensuring that any two load nodes are connected through branches to form a resolvable unified topology. All nodes and branches are renumbered based on preset numbering rules, and the branch direction is uniformly defined according to the power flow direction, ensuring that the numbering direction of each branch is consistent with its terminal node. For converter branches, the AC side is uniformly set as the starting point and the DC side as the ending point to eliminate topological uncertainties caused by bidirectional power flow, thereby forming a directed graph structure with definite directionality.

[0034] In some embodiments, a node-branch association matrix E is established based on the renumbered topology, wherein the elements of matrix E are... Used to characterize the relationship between node i and branch j. When node i and branch j are not connected... When node i is the starting point of branch j, When node i is the endpoint of branch j, The direct involvement of power supply nodes is ignored during the construction process, and only the topological mapping relationship between load nodes and branches is retained. The corresponding column for tie lines is deleted from the node-branch association matrix E to obtain a simplified matrix P. The AC feeder submatrix and DC network submatrix are processed in blocks, and matrix inversion is performed on them while ensuring the invertibility of each submatrix. The absolute value of all elements in the resulting matrix is ​​taken to obtain the upstream and downstream power supply relationship matrix corresponding to each feeder, i.e., the power supply path matrix PSPM. This indicates that branch i is located upstream of the power supply path of node j. This indicates that there is no power supply path dependency. When the DC network has a ring network structure, the DC ring network can be equivalently transformed into a radial structure by introducing virtual nodes or using the minimum spanning tree method to satisfy the reversibility calculation condition of the power supply path matrix, thereby achieving analytical modeling while retaining the flexibility of DC interconnection.

[0035] In some embodiments, the rated power capacity of each converter is collected to form a converter rated capacity matrix (CRC), the active power transmission of each converter under typical operating conditions is collected to form a ground-state operating power matrix (CBP), and the power transmission direction information of each converter is collected to form a power direction identification matrix (CDIR), wherein the CDIR is used to identify whether the converter has AC... DC or DC AC bidirectional transmission capability. Based on the difference between the converter's rated capacity (CRC) and ground-state operating power (CBP), and combined with the power direction identifier (CDIR) for constraint calculation, the remaining available transmission capacity of each converter under different power flow directions is obtained to characterize its power support capability during fault recovery.

[0036] Through the above steps, a unified topology model is performed on AC lines, DC lines, switching equipment, and converters in the AC / DC hybrid distribution network. A directional power supply path analytical model is constructed by combining the remaining available transmission capacity of the converters. This achieves a unified representation of the power supply relationship and power support capacity of the AC / DC network, providing an accurate data foundation for load transfer analysis and power restoration capacity assessment after a fault, thereby improving the accuracy and reliability of load restoration capacity analysis in the AC / DC hybrid distribution network.

[0037] Step S102: Determine the normal power supply path from all power consumption nodes to the power supply node based on the network topology data, perform fault simulation on each branch to determine the faulty branch, and determine whether each normal power supply path contains each faulty branch. If so, determine the power consumption node corresponding to the normal power supply path as the load node that needs to be transferred. Please refer to Figure 2 In some embodiments, determining the normal power supply path from all power-consuming nodes to the power-supplying node based on the network topology data includes steps S201 to S203. Step S201: Construct a node-branch association matrix based on the network topology data to characterize the connection status between each power-consuming node and each branch. In some embodiments, the acquired AC / DC hybrid distribution network topology data is standardized. Low-voltage transformers containing connected users are treated as part of their respective branches, and their failure rates are added to the corresponding branch's failure rate parameters. Simultaneously, the transformer element is deleted to avoid redundant modeling. AC switches, fuses, DC switches, DC circuit breakers, and converters are uniformly abstracted as "special branches," and both ends of each special branch are constrained as load nodes to ensure a describable branch connection between any two load nodes. Based on this, all nodes and branches are renumbered according to preset rules, and the branch direction is uniformly set according to the power flow direction, ensuring that the numbering direction of each branch is consistent with the numbering of its terminal node. For converter branches, the AC side is uniformly defined as the starting point and the DC side as the ending point to eliminate the uncertainty of bidirectional power flow. Finally, a node-branch association matrix E is constructed based on the renumbered topology, where when node i and branch j have no connection relationship... When node i is located at the starting point of branch j, When node i is located at the end of branch j, This forms a node-branch correlation matrix that can fully characterize the distribution network topology.

[0038] Step S202: Delete the matrix column corresponding to the tie line data from the node branch association matrix to obtain the target matrix; perform an inversion operation on the target matrix to obtain the inversion result; take the absolute value of each matrix element in the inversion result to obtain the power supply path matrix; wherein the network topology data includes the tie line data. In some embodiments, the columns corresponding to tie lines are deleted from the node branch association matrix E to obtain a simplified node branch matrix P, where tie lines are branches that are normally open and do not provide continuous power supply under normal operating conditions. Matrix P is divided into blocks according to the feeder structure, and AC feeder sub-matrices and DC network sub-matrices are extracted respectively. Under the premise of ensuring that each sub-matrix is ​​invertible, matrix inversion is performed on each block matrix to obtain the corresponding topology inversion matrix. Furthermore, the absolute values ​​of all elements in the topology inversion matrix are taken to eliminate the influence of directional signs, thereby obtaining the power supply path matrix PSPM corresponding to each feeder. The power supply path matrix PSPM is used to characterize the upstream and downstream power supply dependencies between branches and nodes.

[0039] Step S203: Extract the branches that each power consumption node passes through to the power supply node from the power supply path matrix, so as to determine the corresponding branches as the normal power supply path of each power consumption node.

[0040] In some embodiments, based on the row and column element distribution of the power supply path matrix PSPM, a traversal analysis is performed on the column vector corresponding to any power consumption node j. When branch i is located in the upstream power supply path of power consumption node j, it is determined that branch i is located in the upstream power supply path of power consumption node j. When branch i is determined not to participate in the power supply path of the node, a complete set of upstream branches corresponding to the power consumption node j is formed by determining each branch one by one, and the set of branches is sorted according to the topology number order to obtain the unique or multiple path power supply links between the power consumption node j and the power supply node. Furthermore, in the AC / DC hybrid network scenario, if the same power consumption node corresponds to multiple power supply paths, the main power supply path is selected as the normal operation path output according to the preset power supply strategy (including the main power supply path priority principle or the power allocation priority principle) for subsequent reliability analysis and fault impact assessment.

[0041] In some embodiments, each branch is treated as a faulty branch, and each fault scenario is simulated one by one. It is determined whether each normal power supply path contains each faulty branch. If so, the power consumption node corresponding to the normal power supply path is determined as the load node that needs to be transferred. Specifically, based on the constructed power supply path matrix PSPM, each branch i in the distribution network is sequentially set as a hypothetical faulty branch, and the branch is marked as faulty at the matrix level. That is, the connectivity contribution of the branch in the topology is removed from the set of available power supply paths to simulate the network structure change after the branch fails. For any power consumption node j, based on the corresponding column vector in the power supply path matrix PSPM Check if it exists line by line. In the case of, This indicates that branch i is located upstream of the normal power supply path of node j, and is used to form an effective power supply path support for node j; when branch i is set as a faulty branch, if in Chinese original satisfaction If a critical branch item is removed or becomes invalid, the original main power supply path of node j is determined to be interrupted. After completing the above circuit failure determination, reachability reconstruction analysis is performed on the remaining power supply path of node j. Specifically, based on the corrected power supply path matrix PSPM′ after deleting the faulty branch, it is re-searched to see if there are still paths that satisfy the condition. Other branch roads That is, determine whether node j still has at least one complete alternative power supply path; if no such path exists, it is considered that the alternative path does not exist. If the path is determined, then node j is determined to be in a state of complete power outage under the fault scenario. Combining the AC / DC correlation matrix C and the tie matrix TIE, the power supply capability of node j across feeders and across electrical areas is further verified: if node j can still restore power through tie branches of other feeders or through AC / DC coupling paths formed by converters after the branch i it depends on in the original power supply path is cut off, then the node is marked as a node with transfer reachability; otherwise, it is marked as a non-transferable power outage node. When it is confirmed that all original normal power supply paths of node j are blocked under the fault condition of branch i, and the modified power supply path matrix PSPM′ after deleting the faulty branch, the tie matrix TIE, and the AC / DC correlation matrix C jointly determine that there is still no feasible alternative power supply path, then node j is determined as a load transfer node, and the corresponding set of interrupted original power supply paths is recorded as the set of critical failed branches, used for subsequent steps in transfer path search and power constraint verification analysis, thus providing basic input for fault recovery and load transfer strategies in AC / DC hybrid distribution networks.

[0042] Through the above steps, by constructing a unified node-branch association matrix and deriving the power supply path matrix, the analytical expression and rapid determination of the power supply path of the AC / DC hybrid distribution network are realized. Combined with the failure simulation of each fault branch and the path reachability reconstruction analysis, the power outage nodes and load nodes that need to be transferred to power supply under different fault scenarios can be accurately identified, thereby improving the accuracy of power supply path determination and load recovery analysis of the AC / DC hybrid distribution network under fault scenarios.

[0043] Step S103: In the network topology data after removing the faulty branch, search for transfer paths connected to the preset backup power supply for the load nodes that need to be transferred. Calculate the new transmission power of each transfer path based on the power consumption data corresponding to the obtained transfer path. Based on the new transmission power and the available transmission capacity of the converters through which each transfer path passes, calculate the load transfer amount under each fault scenario. The available transmission capacity is calculated based on the converter operating data. In some embodiments, the step of searching for transfer paths connected to a preset backup power source for each load node requiring transfer in the network topology data after removing the faulty branch includes: extracting tie-line nodes connected to each load node requiring transfer in the network topology data after removing the faulty branch; using each tie-line node as a starting node, tracing step by step along the electrical connection direction in the network topology data until the preset backup power source is found, thereby obtaining the transfer path corresponding to each load node requiring transfer.

[0044] In some embodiments, the tie-line nodes connected to each of the load nodes requiring load transfer are extracted from the network topology data after removing the faulty branch. Specifically, after treating branch i as the faulty branch and completing simulations one by one, based on the judgment result of the fault impact matrix IF, all scenarios that satisfy the impact type of c, c1, c2 or e and correspond to load node j are selected, and such nodes are defined as the set of load nodes requiring load transfer. In the equivalent network topology after removing the faulty branch, based on the power supply path matrix PSPM, segmented switch matrix SE, fuse correction matrix FUSE′, and connection matrix TIE, for each load node requiring transfer, The association is determined item by item, specifically as follows: For any node k, if one of the following three types of topological association conditions is met, then node k is determined to be a tie-line node directly related to load node j: The first type of condition is that a tie exists, that is: Where i represents the index of the branch where the fault occurred, and k represents a node downstream of the faulty branch or in an adjacent power supply area. The second type of condition is that the topology is reachable and a valid switch isolation path exists, i.e.: The above conditions indicate that in the original power supply path, this node belongs to the controllable power supply path boundary node of load node j, and may form a transfer boundary through a switch or fuse. The third type of condition is the existence of cross-regional electrical association, that is, it is satisfied through the AC / DC association matrix C: Where v represents the converter number, this condition is used to identify potential tie nodes that achieve electrical coupling through the converter. Node k satisfying any of the above conditions is uniformly defined as the tie node corresponding to the load node j to be supplied, and constitutes the tie node set. .

[0045] It should be noted that the judgment result of the fault impact matrix IF is determined through the following step-by-step logic: (1) Basic topology relationship judgment result: based on the power supply path matrix Determine the upstream and downstream relationship between branch i and node j: when When branch i is located on the power supply path of node j, it indicates that branch i has an upstream influence relationship with node j; when When this occurs, it indicates that branch i is not on the power supply path of node j, and branch i does not constitute its direct power supply path constraint. This step is used to determine the initial scope of influence, i.e. whether to enter the subsequent "potential influence judgment process". (2) Electrical isolation and transfer condition judgment results: After determining that there is an upstream and downstream relationship, further combine the segmented switch matrix Correcting the fuse matrix and contact matrix Determine the switchability of the power supply path: If and This indicates that there is no effective electrical isolation or protective interruption condition between branch i and node j, and the fault will directly propagate to the node side, with its impact tending towards type a; if or This indicates the existence of electrical isolation, but whether power can be restored depends on the presence of a valid downstream connection; if This indicates that after the fault isolation of branch i, node j has the structural conditions to restore power supply through the tie line, corresponding to the initial power transfer type c; if If no available connection path exists, it indicates that the power cannot be transferred. (3) Converter correlation determination result: In the AC / DC hybrid distribution network, the AC / DC correlation matrix C also needs to be introduced for cross-domain judgment: If node j and converter v have a power supply dependency relationship ( If the faulty branch i or its affected path involves converter power transmission, then the power constraint judgment logic needs to be further entered (corresponding to the source conditions of class C2 or class E influence). (4) The correction effect of power constraint verification results on IF: For those initially judged as class C or class E After path identification is completed, the elements are verified using the converter power margin matrix (CPM): if the sum of the converter power margins on all possible transfer paths meets the transfer requirements, then... Maintain or modify to C1 (full transfer); if only partial transfer requirements are met, then... Revised to C2 (partial power transfer); if the power margin is insufficient to support any power transfer path, then The final revision is a (unable to transfer power or requires waiting for repair); if it involves a converter failure and there is no backup path, then... Classified as e1; if the converter is not faulty but its power is limited, then Classified as e2. (5) Final Fault Impact Matrix Determination method: Based on the above judgment process, each element in the fault influence matrix IF... All are determined step by step through the following steps: Based on Determine whether branch i affects node j; based on , Determine whether electrical isolation conditions exist; based on Determine if an interconnection power transfer path exists; determine if there is a cross-regional power supply dependency of the converter based on C; perform power margin verification on the power transfer path and correct the impact type based on CPM; finally obtain .

[0046] In some embodiments, each of the tie-line nodes is used as a starting node, and the electrical connection direction in the network topology data is traced step by step until a preset backup power source is found, thereby obtaining the transfer path corresponding to each of the load nodes that need to be transferred. Specifically, this involves using the tie-line node set... Taking any node k as the starting point for path search, in the equivalent topology after removing the faulty branch, the path is traced upstream towards the backup power source level by level along the electrical connection direction, based on the connectivity relationship jointly defined by the Power Supply Path Matrix (PSPM) and the Connection Matrix (TIE). During this process, the condition for any node u to extend to the next node v is... Furthermore, during the path expansion process, the connectivity constraints of the sectionalizing switch and the fuse are simultaneously satisfied, i.e. or When a path extends to a node with a backup power supply connection, i.e., a node that can access external power through a connection structure, the path is considered a valid power transfer path and terminates. The backup power supply is determined based on the AC / DC correlation matrix C, i.e., when there exists a converter v such that… Furthermore, since the upstream power supply side corresponding to the converter has the capability to support an external power source, the node to which this path extends can be considered a backup power access node. Therefore, starting from the initial tie-line node k, a complete power transfer path is ultimately formed from the load node j through the tie-line node k and extending to the backup power node, represented as follows: ,in, This represents the set of backup power nodes that can restore power to node j or its power grid after the main power supply path to node j is interrupted, through the tie-line topology or AC / DC converter power transmission path. Backup power includes AC-side backup power nodes, DC-side backup power nodes, and converter-side power nodes with available power margin. Each segment of this path satisfies the topology connectivity conditions jointly constrained by the power supply path matrix PSPM, the switch matrix SE, and the fuse correction matrix FUSE′. All tie-line nodes... The corresponding set of valid paths is summarized to obtain the set of all candidate transfer paths for the load node j that needs to be transferred. This provides a path input basis for power verification based on the converter power margin matrix CPM in subsequent steps.

[0047] In some embodiments, calculating the new transmission power of each transfer path based on the acquired power consumption data corresponding to the transfer path includes: determining the target set of power consumption nodes that have actually resumed power supply on each transfer path; reading the active power data corresponding to each target power consumption node in the target set of power consumption nodes from a preset node load data table, and accumulating the active power data corresponding to the same transfer path to calculate the new transmission power of the corresponding transfer path.

[0048] In some embodiments, determining the target set of power-consuming nodes that have actually had their power restored on each of the transfer paths involves: based on the constructed power supply path matrix PSPM, tie matrix TIE, and AC / DC correlation matrix C, traversing and searching the paths that still meet the connectivity conditions after the fault occurs; wherein, nodes that meet the condition of "still being able to connect to the power supply side through at least one connectivity path consisting of a tie line or converter after fault isolation" are identified as nodes that can have their power restored, and are included in the target set of power-consuming nodes for the corresponding transfer path. Specifically, for any faulty branch i, according to Determine whether node j is located in the area where the original power supply path is interrupted, and combine this with... and Constrain the fault isolation boundary; utilize The system determines whether an alternative power supply channel exists outside the isolation zone. Simultaneously, it uses the AC / DC correlation matrix C to determine whether node j relies on converter v for cross-regional power supply restoration. If, after fault isolation, node j still has at least one path p satisfying connectivity constraints, allowing it to reach node j from either the power source node or the converter's power supply side, then node j is included in the target power consumption node set corresponding to path p. In the path search process, for each candidate path p, connectivity is verified segment by segment in the order of "branch-switch-fuse-tether-converter": when any segment of the path satisfies or or If the current condition is met, then the segment is considered to have the capability to conduct or transfer power; if the path crosses both DC and AC regions, then both conditions must be met simultaneously. The converter association conditions are determined to ensure cross-domain power accessibility. Finally, the set of all nodes that satisfy the above connectivity and cross-domain constraints is summarized to obtain the target power consumption node set corresponding to the power transfer path p. .

[0049] In some embodiments, active power data corresponding to each target power node in the target power node set is read from a preset node load data table, and the active power data corresponding to the same transfer path are accumulated to calculate the new transmission power of the corresponding transfer path. Specifically, the target power node set is... The active power corresponding to any node j in the equation is denoted as . The active power data originates from a pre-set node load data table, which stores the active load value of each node under typical operating conditions according to node number. This represents the set of all target power-consuming nodes corresponding to the same power transfer path p. The nodes in the data are traversed, and their corresponding active power data is extracted; based on this, the transmission power of the newly added path p is... An additive calculation is performed, which involves summing up all the restored load power required by the path to characterize the additional power transmission demand that the transfer path needs to provide after a fault. Specifically, when the set of target power nodes corresponding to path p is... When, the additional transmission power of path p The total load power required by this path is determined by the sum of the active power of all target nodes; that is, the total load power required by this path is equal to the linear sum of the load power of each node in the set. When multiple transfer paths simultaneously restore power to different sets of target nodes, the additional transmission power is calculated independently for each path. This is then used as an input for converter power dynamic margin verification in subsequent steps, and is compared with the converter power margin involved in the corresponding path. By comparing the two paths, we can determine whether the path has full or only partial supply transfer capability.

[0050] Please refer to Figure 3 In some embodiments, the calculation of the load transfer amount under each fault scenario based on each of the newly added transmission power and the available transmission capacity of the converters through which each transfer path passes includes: steps S301 to S303. Step S301: Identify the converters included in each of the power transfer paths, and obtain the rated transmission capacity and current transmission power corresponding to each converter. Calculate the difference between the rated transmission capacity and the current transmission power to determine the available transmission capacity of each converter. In some embodiments, for any power transfer path p, based on the pre-constructed AC / DC correlation matrix C, power supply path matrix PSPM, and connection matrix TIE, the set of converters traversed by the path is determined and denoted as . For any converter Obtain their rated transmission capacity respectively. and current ground state operating power By combining the converter power transmission direction identification matrix CDIR, its operating direction under the current path is determined. Based on this, the available transmission capacity of the converter is calculated. Specifically, it is expressed as: ; in, , This is a converter direction indicator variable used to constrain the converter to participate in capacity calculations only when it has the capability in the corresponding direction.

[0051] Step S302: Select the minimum value from the available transmission capacity of each converter in the same power transfer path, so as to determine the minimum value as the upper limit of the path transmission power of the corresponding power transfer path; In some embodiments, for any transfer path p, the set of available transmission capacities corresponding to all converters in that transfer path is obtained. Because electrical energy needs to pass through each converter in the path sequentially during load transfer, the overall transmission capacity of the path is limited by the converter with the weakest transmission capacity. A minimum value search operation is performed on the set of available transmission capacities: ,in, This indicates the upper limit of the power that can be transmitted along the path corresponding to the transfer path p. These represent the available transmission capacity of each converter in the transmission path. When there is no converter in the transmission path, the minimum remaining transmission capacity of each branch in the path is determined as the upper limit of the transmission power of the path. When the transmission path passes through multiple converters, the minimum available transmission capacity is taken as the upper limit of the transmission power of the path, thus ensuring that no converter will be overloaded during the transmission process. After the calculation is completed, the set of upper limits of the transmission power of each transmission path is obtained: , where m represents the number of optional transfer paths.

[0052] Step S303: Compare each of the newly added transmission power with the upper limit of the transmission power of each path. When the newly added transmission power is not greater than the upper limit of the transmission power of the path, the newly added transmission power is determined as the load transfer amount. When the newly added transmission power is greater than the upper limit of the transmission power of the path, the upper limit of the transmission power of the path is determined as the load transfer amount.

[0053] In some embodiments, let the additional transmission power demand caused by branch i switching to the node set under a fault scenario be . Then, for each candidate power transfer path p, the following power verification judgment is performed: when the following conditions are met... At that time, it is assumed that the transfer path has full carrying capacity, and the load transfer volume is... Pick: When satisfied When the power transfer path is considered to be in a power-limited state, the load transfer amount is truncated according to the upper limit of the path: Meanwhile, to characterize the partial transfer capacity, a transfer ratio coefficient can be defined: Through the above comparison mechanism, a quantitative determination of the load transfer capacity based on converter power constraints in AC / DC hybrid distribution networks can be achieved.

[0054] Through the above steps, by using a joint search mechanism based on the power supply path matrix, tie matrix, and AC / DC correlation matrix, the tie line nodes and reachable transfer paths of each load node that needs to be transferred are accurately identified. Furthermore, by combining the node load data and the available power capacity of the converter, the power transfer path is verified by power constraint. This achieves a unified match between the load transfer path and the actual power supply capacity after a fault, thereby improving the accuracy and reliability of judging the load restoration power supply capacity of the AC / DC hybrid distribution network under fault scenarios.

[0055] Step S104: Evaluate the load recovery capability of the AC / DC distribution network under different branch faults based on the load transfer quantities of each load.

[0056] Please refer to Figure 4 In some embodiments, the assessment of the load recovery capability of the AC / DC distribution network under different branch faults based on the load transfer capacity includes: steps S401 to S404. Step S401: Based on the fault impact types recorded in the preset fault impact matrix and the load transfer amount under each fault scenario, calculate the load transfer ratio corresponding to each power consumption node, and determine the power outage time corresponding to each power consumption node based on the power outage time calculation rules corresponding to each load transfer ratio and each fault impact type. In some embodiments, for any power consumption node j, based on the corresponding element in the fault impact matrix IF The identified fault types (a, b, c1, c2, d, e1, e2), combined with the load transfer amounts for each transfer path obtained from the preceding steps, Determine the load transfer ratio of node j in the case of branch i failure. When the fault type is C1 or B, it is assumed that the load can be fully restored to power. When the fault type is C2 or E2, the calculation is based on the actual power transfer capacity under power-limited conditions. ,in, Indicates the electricity consumption node number. This represents the actual active power that can be provided to node j through the transfer path. This represents the original load demand of power consumption node j. This indicates the load transfer ratio at power consumption node j; when the fault type is a or e1, it is considered that load transfer cannot be achieved. When the fault type is d, the node is considered unaffected. Based on this, and combining the outage time models corresponding to different fault types, the outage time of node j is calculated. Perform a weighted calculation based on the type: For type A and type E1 faults, the power outage time is taken as the branch repair time. For Class B faults, the power outage time is taken as the switch operation time. For C1 type faults, the power outage time is taken as the maximum switching operation time. ,in, Indicates the operation time of the sectionalizing switch. This indicates the operation time of the tie switch; for C2 and E2 type faults, the power outage time is the equivalent power outage time under partial power transfer. ,in, Indicates the fault repair time. This indicates the time for partial power transfer and load control operations. This represents the load transfer ratio. Based on the above rules, the annual outage time for node j is obtained by summing up all branch fault scenarios: ,in, The failure rate of branch i, Let be the equivalent power outage time corresponding to node j for a fault in branch i.

[0057] Step S402: Obtain the failure rate corresponding to each fault branch under each fault scenario, and accumulate the failure rates to calculate the number of power outages corresponding to each power consumption node. In some embodiments, for any node j, based on the failure rate vector Based on the fault impact matrix (IF), the set of all branches that can cause a power outage at node j is calculated. Then the annual number of power outages at node j. Represented as , among which, when It is assumed that a fault in branch i will cause a power outage at node j; when The number of power outages is not included in the cumulative count.

[0058] Step S403: Multiply the power outage time of each power outage with the active power data corresponding to each power consumption node to obtain the power shortage corresponding to each power consumption node. In some embodiments, for any power consumption node j, its load demand active power is obtained. And combined with the annual power outage time of that node Calculate its annual power shortage Specifically: When node j is in a partial transfer state of type c2 or e2, a transfer ratio correction coefficient is introduced. The power shortage is then corrected as follows: ,in, This represents the equivalent average power transfer ratio of the node across all failure scenarios.

[0059] Step S404: Determine the load recovery capability assessment result of the AC / DC distribution network based on the outage time, the number of outages, and the amount of power shortage.

[0060] In some embodiments, the system is assumed to have a total There are users, and the number of users corresponding to each node j is . , forming a user number vector The system average outage frequency (SAIFI) is calculated as follows: The System Average Outage Time (SAIDI) is calculated as follows: The expected power shortage (EENS) of the system is calculated as follows: ;in, This represents the number of users corresponding to power consumption node j. This represents the total number of users in the system. , , These represent the number of power outages, outage duration, and power shortage amount for node j, respectively. Finally, SAIFI, SAIDI, and EENS are combined to form a load recovery capability assessment vector: It is used to characterize the overall reliability level and load recovery capability of AC / DC distribution networks after considering converter power constraints and transfer capacity.

[0061] In some embodiments, determining the load recovery capability assessment result of the AC / DC distribution network based on each of the outage times, each of the outage frequencies, and each of the power shortages includes: calculating the system average outage time by performing a weighted average calculation of each of the outage times and the number of users corresponding to each of the power consumption nodes; calculating the system average outage frequency by performing a weighted average calculation of each of the outage frequencies and the number of users corresponding to each power consumption node; summing up each of the power shortages to calculate the expected system power shortage; and combining the system average outage time, the system average outage frequency, and the expected system power shortage to obtain the load recovery capability assessment result of the AC / DC distribution network.

[0062] In some embodiments, a weighted average calculation is performed on each power outage time and the number of users corresponding to each power consumption node to calculate the system average power outage time. Specifically, let the annual power outage time vector of each power consumption node be... The user count vector corresponding to each node is: The total number of system users is The system average outage time SAIDI is then calculated as follows: ,in, This represents the annual power outage time for the j-th power consumption node. This indicates the number of users corresponding to this node.

[0063] In some embodiments, a weighted average is calculated by taking the number of power outages and the number of users corresponding to each power consumption node to obtain the system average power outage frequency. Specifically, let the annual power outage frequency vector of each power consumption node be... The system average outage frequency (SAIFI) is calculated as follows: ,in, This represents the number of power outages per year for the j-th power consumption node. This indicates the number of users corresponding to this node.

[0064] In some embodiments, the expected power shortage of the system is calculated by summing up the various power shortage amounts. Specifically, let the annual power shortage amount of each power consumption node be... The expected power shortage EENS of the system is then calculated as follows: For scenarios involving partial power transfer or power constraints (C2 or E2 type), the following applies: For other types, then: .

[0065] In some embodiments, the average system outage time, the average system outage frequency, and the expected system power shortage are combined to obtain the load recovery capability assessment result of the AC / DC distribution network, specifically: Where SAIFI represents the system average outage frequency, SAIDI represents the system average outage time, and EENS represents the expected power shortage in the system. These terms are used to comprehensively characterize the overall power supply reliability and load recovery capability of the AC / DC distribution network under the conditions of converter power constraints and transfer capacity.

[0066] In some embodiments, after calculating the fault impact matrix (IF), fault rate vector, repair time vector, and load node attribute data, a Fault Mode and Effects Analysis (FMEA) table is automatically generated to automate the analysis of fault consequences in AC / DC distribution networks. Specifically, a fault impact screening matrix M is established to extract all fault relationships affecting load nodes from the fault impact matrix. The construction rules are as follows: ,in, This represents the element in the i-th row and j-th column of the Boolean filtering matrix M. This indicates the type of impact of a fault in the i-th branch on the j-th load node in the fault impact matrix (IF). Indicates a fault type that has no impact. When When this occurs, it indicates that a fault in branch i will affect node j, and a corresponding FMEA record needs to be generated. For all nodes that satisfy this condition... The fault impact relationships are traversed to form a set of fault impact relationships: ,in, Represents the set of relationships affecting the fault. This represents a set of fault relationships between the i-th faulty component and the j-th affected load node. For the set... Each element in It automatically reads the corresponding basic attribute information; among which the faulty component attributes can be represented as ,in, This represents the set of attributes for the i-th faulty component. Indicates the type of faulty component. This indicates the annual failure rate of faulty components, expressed in times per year. This represents the mean time to repair (MTBL) for faulty components, in hours. Load node attributes can be represented as: ,in, This represents the attribute set of the j-th load node. This represents the node load power, in kW. This represents the number of node users, in units of households. Based on the fault impact type matrix IF obtained from the preceding steps and the power verification results, fault constraint parameters are extracted. If the fault impact type is partial power transfer type c2 or power-limited type e2, the maximum transferable proportion is recorded. ,in, This represents the maximum transferable supply ratio under fault scenario (i,j). This indicates the load power that can be successfully transferred after a fault. This represents the total load demand power of node j. When... When the time is specified, it indicates that only partial power restoration is possible. Calculate the single fault outage time when the fault impact type is a or e1: ,in, This represents the duration of a single power outage caused by a fault in branch i to node j. This indicates the repair time for the faulty branch, meaning the node needs to wait for power to be restored after the fault is repaired; when the fault impact type is b: ,in, This indicates the operation time of the sectionalizing switch. When the fault impact type is c1: ,in, Indicates the operating time of the handover switch. This indicates that the maximum value is taken, meaning the power outage time is the larger of the time required for the isolation operation and the time required for the power transfer operation. When the fault impact type is c2 or e2: ,in, Indicates the fault repair time. Indicates the load transfer control time; This indicates the maximum transferable power ratio. This formula reflects the actual situation where some loads are quickly restored through power transfer, while the remaining loads need to wait for fault repair. After obtaining the single power outage time, calculate the power loss during a single fault. When the fault impact type is a, b, c1, or e1: ,in, This indicates the amount of power lost during a single fault. Indicates the node load power. The duration of a single power outage is expressed in kWh. For partial power transfer type C2 and power-limited type E2, a modified calculation formula is used. ,in, This indicates the proportion of the area where power supply has not been restored. Further calculation of the annual expected contribution of power shortage: ,in, This represents the annual expected power shortage contribution of branch i to node j. Indicates the failure rate. This represents the power loss during a single fault, expressed in kWh / year. After completing the above calculations, for each... Generate an FMEA record based on the fault relationships: ; in, This indicates FMEA records. Indicates power limit symbol. This indicates the limiting converter number; the other variables are defined as before. Finally, all records are sorted by faulty component number and load node number to form a complete FMEA analysis table: FMEA represents the final generated Failure Mode and Effects Analysis table. This represents the set of all fault-related relationships. This indicates a record set merging operation. Using the above method, based on the fault impact matrix, converter power constraint matrix, and reliability index calculation results, an AC / DC distribution network FMEA analysis table can be automatically generated, containing information such as fault mode, impact type, power limitation information, power outage consequences, and power shortage contribution, thus achieving automated processing of the entire fault consequence analysis process.

[0067] In some embodiments, after the fault impact matrix IF is constructed, element-level mapping is performed on the matrix IF to generate a numerical matrix for sensitivity analysis. (1) Construct the power outage number determination matrix IF1: ,in, This indicates the type of fault impact on node j when branch i fails. This indicates a permanent power outage fault. This indicates a switch isolation recovery type fault. This indicates a complete power transfer failure. This indicates a partial power supply failure. This indicates no impact. This indicates a converter shutdown fault. This indicates a power-limited fault in the converter. (2) Construct the outage time matrix IF2: ,in, ; in, This indicates the power outage time at node j caused by a fault in branch i. Indicates the fault repair time of branch i. Indicates the operation time of the sectionalizing switch. Indicates the operating time of the handover switch. Indicates the fault repair time. Indicates the load transfer operation time. This indicates the proportion of power transfer available to node j after a fault in branch i. (3) Calculate the branch fault rate sensitivity: Taking the system average outage frequency SAIFI as an example, calculate the partial derivative of the fault rate of any branch i: ,in, Indicates the failure rate of branch i. This represents the i-th row of matrix IF1. Represents a vector of the number of users in a node. This indicates the number of users corresponding to node j. This represents the total number of users in the system; the corresponding SAIDI sensitivity is calculated as follows: ,in, This represents the i-th row of matrix IF2; the corresponding EENS sensitivity is: ,in, Represents the node load vector. This represents the load demand at node j. After calculation, all branches corresponding to this value will be considered. , and Sort the results. The larger the value in the sorting results, the greater the impact of the corresponding equipment failure rate change on system reliability. (4) Calculate the fault repair time sensitivity: for the repair time of branch i The calculation formula is as follows: ,in, This represents the i-th row of matrix IF3. This represents the failure rate of branch i; the corresponding EENS sensitivity is: The above calculations can identify the key equipment that has the greatest impact on system maintenance efficiency. (5) Calculate converter capacity sensitivity: For converter Rated capacity Calculate its impact on SAIDI: ,in, Indicates the rated capacity of the converter. Indicates the total number of branches. Indicates the total number of nodes. Represents the elements of the power outage time matrix. Indicates the number of node users; corresponding EENS sensitivity: When increasing the capacity of a converter significantly reduces EENS, it indicates that the converter has become a system capacity bottleneck. (6) Calculate the partial power transfer ratio sensitivity: For partial power transfer type faults Calculate the transfer ratio Impact of power shortage: ,in, Indicates all The set of branches / nodes corresponding to a class of faults. Indicates the failure rate of the faulty branch. Indicates node load; This indicates the fault repair time. When the absolute value of this value is large, it indicates that improving the power transfer capability can significantly improve the reliability of power supply. (7) Perform network structure perturbation analysis: Calculate the system indicators in the original network: Then modify the network structure parameters, for example, when adding a segmented switch: ,in Represents the elements of the segmented switch matrix; when adding a tie line: ,in This represents the elements of the relationship matrix. Based on the updated SE and TIE matrices, the failure impact matrix (IF) is regenerated, and the reliability metrics are recalculated. Furthermore, the structural sensitivity was obtained: ,in This indicates the change in reliability indicators before and after structural optimization. (8) Identify weak links based on sensitivity results: Sort all equipment according to their sensitivity values: ,in, This indicates the overall risk index of the equipment. This represents the normalized value of the device sensitivity. This represents the normalized value of the severity of the FMEA consequences. , Indicates the weighting coefficient; further classified according to the comprehensive risk index: (1) If Then it is determined to be a Level 1 weak equipment; (2) If Then it is determined to be a level 2 weak equipment; (3) if If the equipment is deemed to be ordinary equipment, a vulnerability analysis report will be generated. This report will include at least the equipment number, equipment type, failure rate sensitivity, repair time sensitivity, EENS contribution, risk level, and corresponding optimization suggestions. This will provide quantitative data for equipment capacity expansion, network reconfiguration, maintenance plan development, and reliability improvement in AC / DC hybrid distribution networks.

[0068] Through the above steps, based on the hierarchical mapping relationship between fault impact type and load transfer capacity, and combined with the transfer ratio, the power outage time, number of power outages and power shortage are uniformly corrected and weighted, so as to realize the refined quantitative assessment of the power supply restoration process of AC / DC hybrid distribution network under different fault scenarios, thereby effectively improving the accuracy and reliability of the judgment of load power restoration status.

[0069] It is understood that the above-described device embodiments correspond to the method embodiments of the present invention, and can implement the load restoration assessment method for AC / DC distribution networks provided by any of the above-described method embodiments of the present invention. More detailed workflows and principles of this system can be found, but are not limited to, the relevant descriptions of the above methods.

[0070] It should be noted that the device embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can specifically be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0071] Based on the above embodiments of the load restoration assessment method for AC / DC distribution networks, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the load restoration assessment method for AC / DC distribution networks according to any embodiment of the present invention.

[0072] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0073] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0074] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0075] Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the load restoration assessment method for AC / DC distribution networks described in any of the above-described method embodiments of the present invention.

[0076] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0077] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for assessing load restoration in AC / DC distribution networks, characterized in that, include: The network topology data and converter operation data of the AC / DC hybrid distribution network are obtained. The network topology data includes power supply nodes, several branches, several power consumption nodes, and several converters. Based on the network topology data, determine the normal power supply path from all power consumption nodes to the power supply node, perform fault simulation on each branch to determine the faulty branch, and determine whether each normal power supply path contains each faulty branch. If so, determine the power consumption node corresponding to the normal power supply path as the load node that needs to be transferred. In the network topology data after removing the faulty branch, a transfer path connected to a preset backup power supply is searched for the load nodes that need to be transferred. Based on the power consumption data corresponding to the transfer path, the new transmission power of each transfer path is calculated. Based on the new transmission power and the available transmission capacity of the converters through which each transfer path passes, the load transfer amount under each fault scenario is calculated. The available transmission capacity is calculated based on the converter operation data. The load recovery capability of AC / DC distribution networks under different branch faults is evaluated based on the load transfer quantities described above.

2. The load restoration assessment method for AC / DC distribution networks as described in claim 1, characterized in that, Determining the normal power supply path from all power-consuming nodes to the power-supplying node based on the network topology data includes: Based on the network topology data, a node-branch association matrix is ​​constructed to characterize the connection status between each power-consuming node and each branch. The target matrix is ​​obtained by deleting the matrix column corresponding to the tie line data from the node branch association matrix. The target matrix is ​​then inverted to obtain the inversion result. The absolute value of each matrix element in the inversion result is taken to obtain the power supply path matrix. The network topology data includes the tie line data. Extract the branches that each power-consuming node passes through to the power supply node from the power supply path matrix, so as to determine the corresponding branches as the normal power supply path of each power-consuming node.

3. The load restoration assessment method for AC / DC distribution networks as described in claim 1, characterized in that, The step of searching for transfer paths connected to preset backup power sources for each load node requiring transfer power from the network topology data after removing the faulty branch includes: Extract the tie-line nodes connected to each of the load transfer nodes from the network topology data after removing the faulty branch. Starting from each of the aforementioned tie-line nodes, the system traces the electrical connections in the network topology data step by step until a preset backup power source is found, thus obtaining the transfer path corresponding to each of the aforementioned load nodes that need to be transferred.

4. The load restoration assessment method for AC / DC distribution networks as described in claim 1, characterized in that, The step of calculating the additional transmission power for each of the power transfer paths based on the acquired power consumption data corresponding to the power transfer paths includes: Determine the set of target power-consuming nodes that will actually have their power restored on each of the aforementioned power transfer paths; The active power data corresponding to each target power node in the target power node set is read from the preset node load data table, and the active power data corresponding to the same transfer path are accumulated to calculate the new transmission power of the corresponding transfer path.

5. The load restoration assessment method for AC / DC distribution networks as described in claim 1, characterized in that, The load transfer amount under each fault scenario is calculated based on the newly added transmission power and the available transmission capacity of the converters through which each transfer path passes, including: Identify the converters included in each of the power transfer paths, and obtain the rated transmission capacity and current transmission power corresponding to each converter. Calculate the difference between the rated transmission capacity and the current transmission power to determine the available transmission capacity of each converter. The minimum value is selected from the available transmission capacity of each converter in the same power transfer path, and the minimum value is determined as the upper limit of the path transmission power of the corresponding power transfer path; The newly added transmission power is compared with the upper limit of the transmission power of each path. When the newly added transmission power is not greater than the upper limit of the transmission power of the path, the newly added transmission power is determined as the load transfer amount. When the newly added transmission power is greater than the upper limit of the transmission power of the path, the upper limit of the transmission power of the path is determined as the load transfer amount.

6. The load restoration assessment method for AC / DC distribution networks as described in claim 1, characterized in that, The assessment of the load recovery capability of the AC / DC distribution network under different branch faults based on the load transfer capacity includes: Based on the fault impact types recorded in the preset fault impact matrix and the load transfer amount under each fault scenario, the load transfer ratio corresponding to each power consumption node is calculated, and the power outage time corresponding to each power consumption node is determined based on the power outage time calculation rules corresponding to each load transfer ratio and each fault impact type. Obtain the failure rate corresponding to each fault branch under each of the aforementioned fault scenarios, and accumulate the aforementioned failure rates to calculate the number of power outages corresponding to each power consumption node. The power outage time of each power outage is multiplied by the active power data corresponding to each power consumption node to obtain the power shortage corresponding to each power consumption node. The load recovery capability assessment results of the AC / DC distribution network are determined based on the outage time, the number of outages, and the amount of power shortage.

7. The load restoration assessment method for AC / DC distribution networks as described in claim 6, characterized in that, The assessment results of the load recovery capability of the AC / DC distribution network, determined based on the outage time, the number of outages, and the amount of power shortage, include: The system average power outage time is calculated by weighting the outage time of each power outage and the number of users corresponding to each power consumption node. The average power outage frequency of the system is calculated by weighting the number of power outages of each power outage with the number of users corresponding to each power consumption node. The expected power shortage of the system is calculated by summing up all the power shortage quantities mentioned above. The average outage time, average outage frequency, and expected power shortage of the system are combined to obtain the load recovery capability assessment result of the AC / DC distribution network.

8. A load restoration assessment system for AC / DC distribution networks, characterized in that, The load restoration assessment system is used to perform the load restoration assessment method for AC / DC distribution networks as described in any one of claims 1-7.

9. A terminal device, characterized in that, The system includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, it implements the load restoration assessment method for AC / DC distribution networks as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, include: A stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform the load restoration assessment method for AC / DC distribution networks as described in any one of claims 1-7.

Images