Method and system for automatically checking protection parameters of power distribution network based on graph topology

Abstract

The invention discloses a graph topology-based power distribution network protection parameter automatic checking method and system, and belongs to the technical field of power transmission and distribution. The method comprises the steps of obtaining a transformer substation outgoing line protection constant value, a terminal protection constant value, line zero-sequence current data, a topological relation below the transformer substation, line parameters and operation state data of lines, switches and distribution transformers; sVG analysis and power distribution network topological graph construction are carried out; subgraph extraction and hierarchy analysis; line parameter and protection constant value verification, including line parameter verification and protection constant value verification; the line parameter verification comprises branch line segment verification and switch position verification; the protection constant value verification comprises overcurrent I section verification, overcurrent II section verification and zero sequence protection verification. According to the method, automatic checking of the power distribution network protection parameters is realized, the checking efficiency and accuracy are greatly improved, and the method is suitable for a protection constant value checking scene of a complex power distribution network.

Description

Technical Field

[0001] The present invention relates to a method and system for automatically checking protection parameters of a distribution network based on graph topology, and belongs to the technical field of power transmission and distribution. Background Art

[0002] In distribution network operation systems, the accuracy of protection settings directly determines the accuracy of fault isolation and the reliability of the power grid. Traditional manual calibration methods present significant bottlenecks, requiring manual calculation of short-circuit currents, operating time differences, and sensitivity for each level of protection. This makes it easy to miss critical coordination nodes in complex, multi-branch, distributed power generation mesh topologies. In large-scale networks with thousands of feeders, calculations can take hours for a single line, leading to setting cycles of up to several weeks. Furthermore, manual data verification often leads to errors in impedance parameter entry and confusion about current transformer (CT) ratios, creating the potential for over-tripping or refusal to operate. While existing technologies provide basic calculation tools, they rely heavily on manual drawing of distribution network topology diagrams and are unable to automatically parse grid graphics files, such as scalable vector graphics (SVG) or geographic information system (GIS) data. Furthermore, they lack intelligent verification capabilities for cross-level protection coordination. For example, key logic, such as the timing difference between substation 10kV outgoing line protection and trunk line feeder terminal unit (FTU) protection, and the sensitivity connection between branch line protection and user boundary switches, requires manual derivation, resulting in a disconnect between the setting strategy and the actual network. Therefore, a deeply automated solution is urgently needed. This solution uses an intelligent graphic parsing engine to directly extract device symbols, connection relationships, and electrical parameters from SVG files, automatically constructing a topological network with hierarchical attributes. Based on a multi-level coordination verification algorithm, differentiated strategies can be implemented in layers (such as focusing on time difference coordination on the high-voltage side and enhancing sensitivity verification on the low-voltage side). Furthermore, closed-loop verification of protection setting logic across the entire network can be completed within seconds, fundamentally resolving the dual dilemma of efficiency and accuracy. Summary of the Invention

[0003] The purpose of the present invention is to provide a method and system for automatic calibration of distribution network protection parameters based on graph topology, which can automatically parse SVG graphics to construct a distribution network topology map, combine protection setting data and zero-sequence current data, and perform multi-level protection coordination verification, effectively improving the efficiency and accuracy of distribution network parameter calibration.

[0004] The present invention is implemented by the following technical solution: A method for automatically checking distribution network protection parameters based on graph topology, comprising the following steps: Step 1: Data preparation: Obtain substation outgoing line protection settings, terminal protection settings, line zero-sequence current data, topology below the substation, line parameters, and operating status data of lines, switches, and distribution transformers; Step 2: SVG parsing and distribution network topology construction: Parse the distribution line SVG graphic file, extract device information, construct nodes and edges to form a distribution network topology, and complete parameter annotation based on the line ledger; Step 3: Subgraph extraction and hierarchical analysis: Nodes are extracted based on the equipment type code to generate a connected subgraph. With the substation outgoing line switch as the root node, a breadth-first search algorithm is used to perform hierarchical analysis and assign hierarchies. Edges between nodes at the same level are removed to form a tree structure. Step 4: Line parameter and protection setting value verification: including line parameter verification and protection setting value verification; the line parameter verification includes branch line segment verification and switch position verification; the protection setting value verification includes overcurrent I section verification, overcurrent II section verification and zero sequence protection verification; Step 5. Result visualization: Draw a tree topology diagram, color the nodes by level, and simultaneously display the abnormal list table of overcurrent section I, section II, and zero-sequence protection, and output an SVG graphic file.

[0005] Specifically, in step one, the substation outgoing line protection constants include the constants and time of overcurrent sections I, II, and III, and the reclosing time; the terminal protection constants include the on / off status, constants, and time of switch overcurrent sections I and II, and the on / off status, constants, time, and reclosing parameters of zero-sequence protection; the operating status data include switch action information, power outage and restoration events, and voltage and current measurement data.

[0006] Specifically, in step 4, the branch line segment check includes: Calculate the total impedance of the branch line segment based on the conductor segment parameters; Define capacity-length matching, divide intervals based on regional characteristics, and identify abnormal routes using the isolation forest algorithm; A normalized formula is used to calculate the line anomaly score, and lines that exceed the line anomaly score threshold are marked as pending verification.

[0007] Specifically, in step 4, the switch position verification includes: Merge the switch action information during faults to form an action set, and establish an action pool based on region type and protection strategy; Calculate the overlap between the fault area and the power outage area, and mark switches with an overlap below the overlap threshold as pending verification; Two-dimensional clustering is performed based on the average number of switch opening and closing times and the frequency of fault occurrence to identify inefficient switches.

[0008] Specifically, in step 4, the overcurrent I segment check: For 10kV lines outgoing from substations other than 35kV substation lines, the overcurrent I stage protection setting of the switch at this level is 70-95% of that of the upper level switch, and the reclosing time of the switch at this level is less than that of the upper level switch. The setting of this level is 70%-95% of the upper level setting, and the reclosing time is less than that of the upper level switch; For 10kV lines outgoing from 35kV substations, the protection setting value shall be verified to be no less than 70% of the maximum three-phase short-circuit current at the end of the line.

[0009] Specifically, in step four, the zero-sequence protection check must meet the following requirements: the zero-sequence setting does not exceed the upper-level zero-sequence setting, the zero-sequence time does not exceed the upper-level zero-sequence time, the zero-sequence setting is less than the zero-sequence current on the power supply side and greater than the zero-sequence current on the load side, and the difference between the zero-sequence current on the power supply side and the load side is greater than 3A.

[0010] The present invention also provides a distribution network protection parameter automatic calibration system based on graph topology, comprising: Data reading module: used to obtain substation outgoing line protection settings, terminal protection settings, line zero-sequence current data, topology relationship and operation status data; Data fusion module: used to associate multi-source data based on line name and unique ID and perform consistency verification; Distribution network topology construction module: used to parse SVG graphic files, extract device information and connection relationships, and construct a distribution network topology map with parameter annotations; Hierarchical analysis engine: used to extract nodes based on device type codes to generate connected subgraphs, divide hierarchies and form a tree structure; Verification module: includes a line parameter verification submodule and a protection setting value verification submodule; the line parameter verification submodule is used for branch line segment verification and switch position verification; the protection setting value verification submodule is used for overcurrent I section, overcurrent II section and zero sequence protection verification; Visualization module: used to draw tree topology diagrams and exception list tables, and output SVG graphic files.

[0011] Furthermore, the data reading module obtains data from the dispatching system, distribution automation system, and electricity consumption information collection system through the data middle platform and business middle platform interfaces, and supports multiple forms of access such as files, databases, and interfaces.

[0012] The present invention also provides an electronic device, including a memory and a processor, wherein the memory stores computer-readable instructions, and when the instructions are executed by the processor, the processor implements the above-mentioned automatic calibration method for distribution network protection parameters based on graph topology.

[0013] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the computer program implements the above-mentioned method for automatic calibration of distribution network protection parameters based on graph topology.

[0014] The present invention has the following advantages: By automatically parsing SVG graphic files to construct distribution network topology maps, the traditional manual topology drawing time of several hours to several days is shortened to less than 1 minute; the batch processing function supports the simultaneous verification of multiple SVG graphic files, compressing the verification cycle of thousands of feeders from several weeks to several hours, significantly reducing labor costs.

[0015] Eliminate the risk of errors in manually entering data such as impedance parameters and CT ratios, identify abnormal lines and switches through intelligent methods such as the isolation forest algorithm and two-dimensional clustering, reduce omissions caused by manually deducing protection coordination logic, and reduce the hidden dangers of over-tripping or refusal to operate.

[0016] There is no need to rely on manual drawing of distribution network topology diagrams or master dedicated drawing software. The verification process can be started only through standard SVG graphic files, which lowers the technical threshold. Visual integration realizes the linkage between diagrams and numbers, and abnormal nodes are highlighted to facilitate quick problem location.

[0017] The mesh topology is simplified into a tree structure through hierarchical pruning technology. Combined with differentiated verification strategies based on voltage levels (such as differentiated verification of 10kV lines exiting 35kV and non-35kV substations), it adapts to complex distribution networks with distributed power sources and multiple branches, ensuring that the protection coordination logic is consistent with the actual network.

[0018] Through full-link protection coordination and verification (from substation outgoing lines to user-side switches), we ensure step-by-step isolation and power transfer to non-fault areas in the event of a fault, reduce the scope of power outages, and improve the stability and reliability of distribution network operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Flow chart of the method of the present invention.

[0020] Figure 2 Schematic diagram of the system module of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described below with reference to the embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by persons skilled in the art based on the above-mentioned invention contents still fall within the scope of protection of the present invention. Example 1

[0022] like Figure 1As shown, a method for automatic calibration of distribution network protection parameters based on graph topology includes: Step 1: Data preparation: Obtain the substation outgoing line protection settings, including the substation, switch, overcurrent stage I, overcurrent stage II, and overcurrent stage III settings and times, reclosing time, etc. Overcurrent stage I is instantaneous current quick-break protection, set to avoid the maximum short-circuit current at the end of the line. Overcurrent stage II is time-limited current quick-break protection, coordinated with overcurrent stage I of the adjacent line. Overcurrent stage III is time-limited overcurrent protection, set to avoid the maximum load current. Obtain terminal protection settings: including the switch's overcurrent I and II alarms, and the output switch-on / off status, settings, and time; the zero-sequence protection switch-on / off status, settings, and time; and the reclosing switch-on / off and time; Obtain line zero-sequence current data: including the zero-sequence current on the power supply side and the zero-sequence current on the load side of the line; Obtain the following topological relationships and line parameters of the substation; obtain the operating status of the line, switch, and distribution transformer: including switch action information, power outage and restoration events at all levels, and voltage and current measurement data.

[0023] The source systems for acquiring data include the power dispatching system, distribution automation system, power homologation system, and electricity consumption information collection system, and the acquisition method is the data middle platform and business middle platform interface.

[0024] Step 2: SVG parsing and distribution network topology construction: Parse the distribution line SVG graphic file, extract the device information in the metadata tag, construct nodes and edges, the node ID is the unique identifier of the device, and the edge represents the device connection relationship, forming a distribution network topology map. Combined with the line ledger, complete the distribution network topology map parameter annotation.

[0025] Step 3: Subgraph extraction and hierarchical analysis: Extract nodes based on the equipment type code (e.g., 11100000 for line switches and 30500000 for substation outgoing line switches) to generate a connected subgraph. Use the substation outgoing line switch (equipment type code 30500000) as the root node and use the breadth-first search algorithm (BFS) to perform hierarchical analysis and assign a level to each node. Remove edges between nodes at the same level, retain the tie switch nodes and edges, and mark them as standby connections. Add a simulated scenario of tie switch closure during fault verification to evaluate the effectiveness of protection coordination under the transfer state, ultimately forming a tree structure.

[0026] Step 4: Verify line parameters and protection settings: Step 4.1: Line parameter verification The line parameters that affect the protection settings mainly include line length, topology and switch position. The branch line parameters and switch position are verified below.

[0027] (1) Branch line segment verification According to the construction of the distribution network topology diagram and the results of hierarchical analysis, a single-line topology diagram is formed according to the substation-feeder segment-branch segment-distribution transformer. The ledger and topological relationship of the substation-feeder segment-distribution transformer are generally relatively accurate, while the accuracy and rationality of the ledger and topological relationship of the branch segment-distribution transformer need to be further verified.

[0028] Calculate the total impedance at any location on the branch line based on the conductor segment parameters: , , in, is the branch line segment to be calculated, Indicates the number of segments, For the Segment resistance per unit length, is the total resistance of the branch line segment, For the The reactance per unit length of the segment, is the total reactance of the branch line segment, is the segment length.

[0029] The capacity-length matching degree is defined based on the capacity of the distribution transformer connected to the branch line segment and the length of the branch line segment: , Among them, Q is the total capacity of the distribution transformer connected to the branch line segment, The capacity-length matching degree of the branch line segment to be calculated is ρ. Considering regional characteristics (urban, rural, and township), load density, and load growth, the capacity-length matching degree ρ is aggregated by region and standardized. The results are then divided into intervals based on the total capacity of the distribution transformer and the branch line segment length. Within each interval, the feature space is randomly partitioned based on the capacity-length matching degree. Sample features are extracted multiple times with or without replacement to construct t binary trees. Anomalous lines that do not meet parameter accuracy and rationality are isolated earlier in the recursive process. The isolation forest identifies anomalous lines as observations with shorter average paths within the tree.

[0030] The line anomaly score is calculated using a normalized method: , in, For the Line samples in this interval The anomaly score in the line samples, For the The path length of the line sample on the binary tree, For the The mean path length of line samples on t binary trees, for The average path length on the sample binary tree. The closer the score is to 1, the more obvious the abnormal characteristics are, indicating that the capacity-length matching degree between the distribution transformer capacity connected to the corresponding branch line segment and the line length is low. There may be errors in line length, branch line-distribution transformer topology, unreasonable branch line segmentation, etc. A line abnormality score threshold is set, and lines with scores above the line abnormality score threshold are further verified.

[0031] (2) Switch position verification When the switch position is configured reasonably, it should be able to correctly isolate the faulty area and transfer power to the non-faulty area in the event of a fault. Otherwise, isolation will fail or the faulty area will be expanded.

[0032] Based on the formed topological hierarchical relationship, each action information of the switch in the fault is merged to form the action set of each level of switch during the fault, including the opening and closing status and number of switches at each level under the line during the fault. According to the different strategies, the action sets of similar faults in the area are used to establish an action pool. For example, if a line has protection strategy but not automation strategy, the order of all switches on the line from substation to terminal is K=[K1,K2,…,K s ], the number of times the switch is opened when a fault occurs is F=[F1,F2,…,F s ], the number of switch closing times is H=[H1,H2,…,H s ], the fault range is G=[G1,G2,…,G s ], the influence range is W=[W1,W2,…,W s ], where s is the number of automation and protection switches on the line, K is the order of switches on the line, and K s is the sth switch, F is the number of times each level switch is opened during a fault, F s is the number of times the sth switch is opened, H is the number of times the switches at each level are closed during the fault, and H s is the number of times the sth switch is closed, G is the number of stations within the fault range under each level of switch during the fault, G s is the number of power distribution areas under the sth switch in the fault range, W is the number of power distribution areas under the protection range of each level of switch in the fault, W s The number of substations experiencing power outages within the protection range of the sth switch during a fault. Based on the classification of urban, township, and rural areas, the switch opening and closing states and times during faults for lines with similar strategies within a certain range are collected to establish an action pool R. Based on action pool R, the rationality of the switch position configuration is further verified.

[0033] Calculate the overlap γ between the fault area and the power outage area in each fault: , Set the overlap threshold y. If γ < y occurs more than twice, or the average overlap within the calculation period is less than the overlap threshold, it indicates a low overlap, the power outage range expands during a fault, and the corresponding switch configuration position has a poor effect. It is necessary to further verify whether the switch position and protection setting values are reasonable.

[0034] Furthermore, conduct an evaluation of the switch operation effectiveness, cluster the number of switch opening and closing operations in similar faults, and identify high-efficiency and low-efficiency switch groups.

[0035] Construct a feature engineering: average number of switch opening and closing operations = (number of switch opening and closing operations (F + H)) / number of faults, fault occurrence frequency = number of faults c within the protection range of the switch at this level / number of faults. It can be determined that the fault occurs within the protection range of the c-level switch by the number of distribution transformers G within the fault range under each level of switch during the fault.

[0036] Based on the two features of the average number of switch opening and closing operations and the fault occurrence frequency, set the weights of the two features, and use a clustering method, such as kMeans or random forest, to perform two-dimensional weighted clustering on the switches. Pay attention to two types of switches: low operation times / high fault frequency and high operation times / low fault frequency. It is necessary to further verify whether the switch position and protection setting values are reasonable.

[0037] Step 4.2, Protection Setting Value Verification (1) Overcurrent I-section Verification For 10kV lines that are not the outgoing lines of 35kV substations: Trace back from the terminal node upwards to find the nearest upstream switch (including the substation outgoing line switch) with overcurrent I-section protection already in operation. Verify according to the principle that the setting value at this level does not exceed 95% of the upstream setting value and is not lower than 70% of the upstream setting value (or 70% of the maximum three-phase short-circuit current at the line end), and the reclosing time should be less than the upstream reclosing time; for 10kV lines that are the outgoing lines of 35kV substations, only verify the coordination between the terminal node and the upstream non-root node (non-substation outgoing line switch), and verify according to the principle that the lower limit of the setting value is taken as 70% of the maximum three-phase short-circuit current at the line end.

[0038] (2) Overcurrent II-section Verification Trace back from the terminal node upwards to find the nearest upstream switch (the substation outgoing line switch uses the overcurrent III-section setting value) with overcurrent II-section protection already in operation, and verify according to the principle that the setting value at this level does not exceed the upstream setting value and is not lower than 90% of the upstream setting value.

[0039] (3) Zero-sequence Protection Verification Trace upward from the terminal node to find the nearest upper-level switch that has been put into zero-sequence protection, and perform verification according to the rules that the zero-sequence setting does not exceed the upper-level zero-sequence setting, the zero-sequence time does not exceed the upper-level zero-sequence time, the zero-sequence setting is less than the zero-sequence current on the power supply side, the zero-sequence setting is greater than the zero-sequence current on the load side, and the difference between the zero-sequence current on the power supply side and the zero-sequence current on the load side is greater than 3A.

[0040] Step 5. Result visualization: Draw a tree topology diagram, color the nodes by level, display three tables of verification results on the right (overcurrent stage I, overcurrent stage II, and zero-sequence protection anomaly list), output an SVG graphic file, and save it.

[0041] This method can automatically extract topological relationships from SVG graphic files and automatically complete the overcurrent I, overcurrent II, and zero-sequence automatic verification of line terminal switches, greatly improving the correctness of switch actions and the accuracy of distribution network protection.

[0042] (1) Automated topology construction: By parsing the distribution line SVG graphic file, the distribution network topology diagram is automatically constructed without manual drawing, completely eliminating the traditional tedious and time-consuming process of manually drawing or importing complex distribution network topology diagrams in dedicated software; only need to provide a standard SVG graphic file, the system can automatically identify and extract the electrical connection relationship, shortening the topology construction time from hours or even days to less than 1 minute, reducing human errors, and automatically parsing and extracting information directly from the source graphic, minimizing the topology structure errors introduced by human intervention, and significantly improving the accuracy of the input data for subsequent verification. There is no need to master the complex operations of specific drawing software, and only need to prepare or export the standard SVG graphic file to start the topology construction, which reduces the technical threshold and operation complexity.

[0043] (2) Hierarchical pruning technology: Based on breadth-first search (BFS), hierarchical analysis is performed to prune connections at the same level, forming a tree structure and simplifying the verification logic. By intelligently identifying the electrical hierarchy (e.g., substation outgoing line -> trunk line -> branch line -> user) and accurately pruning redundant connections within the same voltage level (e.g., tie lines at the same level), the original network is automatically simplified into a clear, loop-free tree-like radial structure.

[0044] (3) Multi-level protection coordination verification: Consider the coordination between substation outgoing line protection and terminal protection, and adopt different strategies for different voltage levels. Through the contents described in steps 4.1 and 4.2, the full-link coordination verification is achieved, and the complete coordination chain from the protection device of the substation 10kV outgoing line switch (master station level) to the feeder terminal (FTU / DTU) protection (such as overcurrent and zero sequence protection) in the middle and rear sections of the line and the user side protection (such as user boundary switch) is systematically considered to ensure selective and step-by-step tripping in the event of a fault; the verification strategy is refined, and different verification rules and criteria are applied according to the characteristics and coordination requirements of protection equipment at different voltage levels (such as 110kV / 35kV substation outgoing line, 10kV main line, 10kV branch line, 0.4kV user side).

[0045] For example: For lines with frequent power outages or low reliability, focus on switch position verification and protection setting verification; for lines with more ground faults, focus on zero-sequence protection verification; substation outgoing lines focus on differential coordination with the head-end protection of the lower-level main line, main line protection focuses on differential coordination with branch line protection and user boundary protection as well as sensitivity verification, user-side protection focuses on the rationality of its own setting and coordination with the upper-level protection; improve the reliability of the protection system, and through the coordination verification of steps 4.1-step 4.2, minimize the risks of over-tripping (lower-level fault causing upper-level tripping) and refusal to operate (protection that should operate does not operate), and optimize line parameters and protection setting settings.

[0046] (4) Visual integration: The distribution network topology diagram and the verification result table are integrated into one diagram to intuitively display abnormal information. The abstract verification results (tabular data) are closely combined with the intuitive distribution network topology diagram in the same view to achieve the linkage between diagram and data. The abnormality is accurately located by directly highlighting (such as color change, flashing, special marking) the specific equipment (switch, line section) or protection device where the problem is found on the distribution network topology diagram, so as to locate the fault point or the poor coordination point; the results are presented intuitively, and the key verification results (such as unreasonable time difference, set value exceeding the limit) are clearly marked next to the equipment or line or linked to the detailed result table, so that complex technical conclusions can be seen at a glance.

[0047] (5) Batch processing: supports batch processing of multiple SVG graphic files and automatically generates summary reports. It can import and automatically process all SVG graphic files of the entire area, multiple feeders or the entire project at one time. The processing capability far exceeds the operation of single files one by one, which greatly improves work efficiency: For scenarios that require analysis of a large number of lines or the protection coordination of the entire network (such as fixed value setting season, planning assessment, and acceptance after transformation), the batch processing function compresses the manual work that originally took weeks to a few hours or even shorter, freeing up a lot of human resources; the summary report provides a macro view of the protection coordination status of the entire network, which makes it easier for managers to quickly grasp the overall weak links and common problems, and to prioritize and allocate resources. Example 2

[0048] like Figure 2 As shown in the figure, a distribution network protection parameter automatic calibration system based on graph topology includes the following modules: The data reading module is responsible for the collection and access of all data, providing basic data support for subsequent verification. The data range includes: Substation outgoing line protection settings: including substation name, switch number, settings and action time of overcurrent section I / II / III, reclosing time, etc. (overcurrent section I is instantaneous current quick-break protection, adjusted according to avoid the maximum short-circuit current at the end of this line; overcurrent section II is time-limited current quick-break protection, coordinated with overcurrent section I of the adjacent line; overcurrent section III is time-limited overcurrent protection, adjusted according to avoid the maximum load current).

[0049] Terminal protection settings: including the switch overcurrent section I / II alarm and the output switching status, setting, and action time, the zero-sequence protection switching status, setting, and action time, the reclosing switching status and time, etc.

[0050] Line zero-sequence current data: zero-sequence current on the line power supply side and zero-sequence current on the load side.

[0051] Topology and operation data: topological relationships of equipment below the substation, line parameters (length, impedance, etc.), and the operating status of lines, switches, and distribution transformers (switch action information, power outage and restoration events, voltage / current measurement data, etc.).

[0052] Data source and access method: Through the data middle platform and business middle platform interfaces, data is obtained from source systems such as the dispatching system, distribution automation system, and electricity consumption information collection system, supporting multiple forms of access such as files (such as SVG graphic files), databases (structured constant data), and interfaces (real-time operation data).

[0053] The data fusion module is used to realize the association and consistency verification of multi-source data, ensure data connectivity, and provide a unified data foundation for topology construction and verification.

[0054] Association rules: Based on the line name, unique ID (such as switch number, line ID), and the mapping relationship between the dispatching system and the distribution automation system, substation outgoing line protection settings, terminal protection settings, zero-sequence current data, topology parameters, etc. are associated into a unified data set; Consistency check: Automatically check data formats (such as time format and current units) and logical associations (such as the matching of switch numbers and the circuits they belong to), eliminate duplicate or conflicting data, and ensure data accuracy.

[0055] Distribution network topology map construction module, used to automatically parse SVG graphics and construct distribution network topology maps; Hierarchical analysis engine, used to extract subgraphs and divide hierarchies of distribution network topology, simplifying verification logic; Verification module, used to perform automatic verification of line parameters and protection settings; The verification module includes: Line parameter verification submodule, used for branch line segment verification and switch position verification; Protection setting value verification submodule, used for overcurrent I stage verification, overcurrent II stage verification and zero sequence protection verification; The visualization module is used to present the verification results in a visual form. Example 3

[0056] This embodiment provides an electronic device, including a memory and a processor, wherein the memory stores computer-readable instructions. When the instructions are executed by the processor, the processor implements the method for automatic calibration of distribution network protection parameters based on graph topology described in Example 1. Example 4

[0057] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for automatically checking distribution network protection parameters based on graph topology described in Example 1 is implemented.

[0058] The above description merely represents preferred embodiments of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above disclosure to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for automatic calibration of distribution network protection parameters based on graph topology, characterized in that: The following steps are involved: Step 1: Data preparation: Obtain substation outgoing line protection settings, terminal protection settings, line zero-sequence current data, topology below the substation, line parameters, and operating status data of lines, switches, and distribution transformers; Step 2: SVG parsing and distribution network topology construction: Parse the distribution line SVG graphic file, extract device information, construct nodes and edges to form a distribution network topology, and complete parameter annotation based on the line ledger; Step 3: Subgraph extraction and hierarchical analysis: Nodes are extracted based on the equipment type code to generate a connected subgraph. With the substation outgoing line switch as the root node, a breadth-first search algorithm is used to perform hierarchical analysis and assign hierarchies. Edges between nodes at the same level are removed to form a tree structure. Step 4: Line parameter and protection setting value verification: including line parameter verification and protection setting value verification; the line parameter verification includes branch line segment verification and switch position verification; The protection setting value verification includes overcurrent I stage verification, overcurrent II stage verification and zero sequence protection verification; Step 5. Result visualization: Draw a tree topology diagram, color the nodes by level, and simultaneously display the abnormal list table of overcurrent section I, section II, and zero-sequence protection, and output an SVG graphic file.

2. The method for automatic calibration of distribution network protection parameters according to claim 1, characterized in that: In step one, the substation outgoing line protection constants include the constants and time of overcurrent sections I, II, and III, and the reclosing time; the terminal protection constants include the on / off status, constants, and time of switch overcurrent sections I and II, and the on / off status, constants, time, and reclosing parameters of zero-sequence protection; the operating status data include switch action information, power outage and restoration events, and voltage and current measurement data.

3. The method for automatic calibration of distribution network protection parameters according to claim 1, characterized in that: In step 4, the branch line segment verification includes: Calculate the total impedance of the branch line segment based on the conductor segment parameters; Define capacity-length matching, divide intervals based on regional characteristics, and identify abnormal routes using the isolation forest algorithm; A normalized formula is used to calculate the line anomaly score, and lines that exceed the line anomaly score threshold are marked as pending verification.

4. The method for automatic calibration of distribution network protection parameters according to claim 1, characterized in that: In step 4, the switch position verification includes: Merge the switch action information during faults to form an action set, and establish an action pool based on region type and protection strategy; Calculate the overlap between the fault area and the power outage area, and mark switches with an overlap below the overlap threshold as pending verification; Two-dimensional clustering is performed based on the average number of switch opening and closing times and the frequency of fault occurrence to identify inefficient switches.

5. The method for automatic calibration of distribution network protection parameters according to claim 1, characterized in that: In step 4, the overcurrent I stage check: For 10kV lines not originating from 35kV substations, the overcurrent I protection setting of the switch at this level is 70-95% of that of the upper level switch, and the reclosing time of the switch at this level is shorter than that of the upper level switch; The protection setting value of the 10kV line outgoing from the 35kV substation shall not be less than 70% of the maximum three-phase short-circuit current at the end of the line.

6. The method for automatic calibration of distribution network protection parameters according to claim 1, characterized in that: In step 4, the zero-sequence protection check must meet the following requirements: the zero-sequence setting does not exceed the upper-level zero-sequence setting, the zero-sequence time does not exceed the upper-level zero-sequence time, the zero-sequence setting is less than the zero-sequence current on the power supply side and greater than the zero-sequence current on the load side, and the difference between the zero-sequence current on the power supply side and the load side is greater than 3A.

7. A system for implementing the method for automatically checking distribution network protection parameters according to any one of claims 1 to 6, characterized in that: include: Data reading module: used to obtain substation outgoing line protection settings, terminal protection settings, line zero-sequence current data, topology relationship and operation status data; Data fusion module: used to associate multi-source data based on line name and unique ID and perform consistency verification; Distribution network topology construction module: used to parse SVG graphic files, extract device information and connection relationships, and construct a distribution network topology map with parameter annotations; Hierarchical analysis engine: used to extract nodes based on device type codes to generate connected subgraphs, divide hierarchies and form a tree structure; Verification module: including line parameter verification submodule and protection setting value verification submodule; The line parameter check submodule is used for branch line segment check and switch position check; The protection setting value check submodule is used for overcurrent I section, overcurrent II section and zero sequence protection check; Visualization module: used to draw tree topology diagrams and exception list tables, and output SVG graphic files.

8. The system according to claim 7, characterized in that The data reading module obtains data from the dispatching system, distribution automation system, and electricity consumption information collection system through the data middle platform and business middle platform interfaces, and supports multiple forms of access such as files, databases, and interfaces.

9. An electronic device comprising a memory and a processor, wherein the memory stores computer-readable instructions, wherein: When the instruction is executed by the processor, the processor implements the method for automatic calibration of distribution network protection parameters as described in any one of claims 1 to 6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for automatically checking distribution network protection parameters according to any one of claims 1 to 6 is implemented.

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