Method and system for topology identification and ranging of distribution network terminal

Abstract

A method and system for topology identification and ranging of a distribution network terminal. In the method, a binary tree is generated on the basis of data such as poles and towers, switches, and lines; when a line fault occurs, a reference terminal and a valid terminal are determined on the basis of wavefront arrival time data; then, a binary tree algorithm is used for topology identification to locate a fault section and perform ranging, adapting to topology changes caused by changes in switch positions

Description

A method and system for topology identification of distribution network ranging terminals

[0001] Related applications

[0002] This application claims priority to Chinese Patent Application No. 202410664757.4, filed on May 27, 2024, entitled “A Method and System for Topology Identification of Distribution Network Ranging Terminal”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of power distribution network fault location technology, and in particular to a 10kV power distribution line fault location device and its topology identification method and system. Background Technology

[0004] The power distribution network is a crucial hub connecting the transmission chain and power users, and its power supply reliability directly affects users' production and daily life. Compared with transmission lines, the power distribution network has a higher structural complexity, a higher frequency of faults, and is prone to causing power outages and economic losses for users. Some grounding faults can even lead to serious accidents such as electric shock and forest fires. Therefore, efficient fault monitoring and rapid and accurate fault location are of great significance for fault diagnosis and hazard elimination in the power distribution network.

[0005] Rapid fault location and troubleshooting has always been a pressing issue for power distribution networks. The development of distribution network automation and local protection, low-current grounding fault location, and intelligent distributed technologies has enabled rapid and selective isolation of faulty sections to prevent further escalation of accidents. However, accurately pinpointing the exact location of line faults remains difficult, still requiring significant manpower and resources to investigate the fault points.

[0006] Traveling waves possess advantages such as fast response speed, independence from power electronic equipment control, insensitivity to line distributed capacitance and transition resistance adjustment, and high ranging accuracy. Currently, some regions have piloted pole-mounted switchgear with traveling wave ranging function based on the current traveling wave method, with good results.

[0007] However, distribution networks are characterized by complex grid structures, numerous branches, frequent power transfers, and complex and frequently changing topologies. Therefore, a convenient and effective method is needed to identify and locate faulty sections in distribution network topology. Existing technologies, typical distribution network fault location methods, include: traveling wave network fault location methods based on Dijkstra's algorithm, graph theory-based traveling wave fault location methods, and distribution network fault ranging methods based on line normalization and network decoupling.

[0008] One existing technology is a multi-branch transmission line fault location method based on the binary tree principle. Its shortcomings include selecting two reference nodes based on the transient signal amplitude, measuring the distance between these two reference nodes, and using the peak time as the fault time for calculation, neglecting the error caused by amplitude and phase attenuation during traveling wave transmission. Furthermore, it is prone to misjudgment when the fault point is in the T-junction region. All remaining nodes need to have their time difference with reference node 1 calculated. After determining reference nodes 1 and 2, it is necessary to traverse the paths from these two nodes to the root node, resulting in a large computational load when there are many junctions. In addition, there is an existing technology for distribution network fault traveling wave location based on binary trees and multi-terminal time information. Its shortcomings include the need for multiple traversals when generating the binary tree, requiring matrix calculations, leading to extremely high computational loads in multi-branch cases. It is worth noting that these existing technologies all require matrix calculations for topology identification and fault segment location, resulting in large computational loads and complex implementation. Summary of the Invention

[0009] The purpose of this application is to provide a topology identification method based on binary trees. This method uses a binary tree algorithm for topology identification, which has low computational cost and is easy to implement. It can solve the problem that in the past, when the distribution network topology was complex, it was necessary to manually divide the faults or use complex calculations to identify the fault sections.

[0010] To achieve the above objectives, the solution proposed in this application is:

[0011] The first aspect of this application provides a method for topology identification and ranging of distribution network terminals, including the following steps:

[0012] Step 1: Generate a binary tree based on the distribution network topology data, with towers, ranging terminals, and boundary switches as nodes in the binary tree, and input the node information;

[0013] Step 2: When a fault occurs, take the ranging terminal that first measured the traveling wave front as the reference terminal Tj, traverse the binary tree around the reference terminal to find the valid terminal Tn, and calculate the wave front time difference Δtn between it and the reference terminal, where n is the valid terminal number.

[0014] Step 3: The effective segment is the segment whose wavefront time difference Δtn between each effective terminal Tn and the reference terminal Tj is less than the length between the effective terminal and the reference terminal.

[0015] Step 4: Calculate the distance to the fault point within the effective section using the two-end distance measurement formula.

[0016] In one embodiment, the node information includes: the line length L to the left and right child nodes, the normalized length LN, the node name, the child node name, the type, and the wave velocity s; the normalized length LN is expressed by the following formula:

[0017] In the formula:

[0018] LN represents the normalized length.

[0019] L represents the length of the line to the left and right child nodes.

[0020] s1 represents the wave velocity of the first segment of the line, s n This indicates the wave velocity of line n.

[0021] In one embodiment, a binary tree linked list is automatically generated based on node information. Each node in the binary tree linked list contains the following elements:

[0022] Parent points to the parent node, and the first end of the line is none;

[0023] Child-left points to the child node, and the end of the line is none;

[0024] Child-right points to a child node or a sibling node;

[0025] Name, the node name, corresponds to the pole number or switch number;

[0026] DeviceID, the node terminal number, corresponds to the DeviceID number of the terminal waveform. It is none when the node has no terminal.

[0027] Size_signal, node signal strength;

[0028] The distance from Distance-left and Distance-right to the next level node;

[0029] Speed-left, Speed-right to the next level node wave speed;

[0030] The normalized distance left and normalized distance right are the distances from the normalized distance to the next level node, which are the normalized distances from the first node's line.

[0031] In one embodiment, Child-right, which points to a child node or sibling node, specifically includes: none when there is no T-connection, and points to the T-connection child node when there is a 3-terminal T-connection. If there are multiple 3-terminal T-connections, multiple sibling nodes need to be added. The sibling node name is the same as the original node, and the suffix is ​​added with two underscores and numbers to distinguish it from the ordinary node name.

[0032] Name, the node name specifically includes: when there are multiple sibling T nodes, the node name is distinguished by adding double underscores "__".

[0033] In one embodiment, for a ring network line, when generating a binary tree, the substation side is the starting point or the end point. After generating a binary tree with one end as the starting point and the other end as the ending point, it is not necessary to generate a binary tree at the other end.

[0034] In one embodiment, in step 2, when a fault occurs, the received traveling wave head time is stored in the node information, the wave head times are sorted to find the earliest terminal as the reference terminal Tj, the fault point is upstream or downstream of the reference terminal, and the binary tree is traversed upstream and downstream respectively to find the effective terminal Tn directly adjacent to the reference terminal.

[0035] In one embodiment, in step 3, if the effective segment is 1 segment, the fault point is located within the effective segment; if the effective segment is greater than 1 segment, a fault has occurred in the T-connected line.

[0036] In one embodiment, in step 4, the distance to the fault point in each effective segment is calculated according to the two-end distance measurement formula. If there is only one effective segment, the direct output result is given. If there are multiple effective segments that include T-connection lines, and all segment results are near the T-connection, the fault point is located at the T-connection. If one segment result is not near the T-connection, and the results of other segments are near the T-connection, the fault point is in the segment that is not near the T-connection.

[0037] In one embodiment, the method further includes:

[0038] Step 5: Convert the result calculated in Step 4 back to the distance before normalization and locate it on the tower.

[0039] A second aspect of this application provides a system for topology identification of a distribution network ranging terminal, and a method for topology identification and ranging of a distribution network terminal, comprising:

[0040] The binary tree generation module is used to generate binary trees based on the distribution network topology data;

[0041] The lookup module is used to locate the baseline terminal Tj and the valid terminal Tn in the event of a fault.

[0042] The ranging module calculates the effective segment based on the node information of the reference terminal Tj and the effective terminal Tn, and calculates the distance to the fault point within the effective segment.

[0043] Compared with the prior art, the beneficial effects of this application include at least the following: after adopting the above scheme, this application can achieve rapid and accurate topology identification with very little computational load, without manual intervention, reducing workload and facilitating the promotion of traveling wave ranging in distribution networks. Attached Figure Description

[0044] Figure 1 is a logic diagram of one embodiment of this application;

[0045] Figure 2 is an example of a site topology diagram in one embodiment of this application;

[0046] Figure 3 is a schematic diagram of generating a linked list based on the database topology in one embodiment of this application.

[0047] Figure 4 is a schematic diagram of multiple T-connections in one embodiment of this application. Detailed Implementation

[0048] The technical solution and beneficial effects of this application will be described in detail below with reference to the accompanying drawings.

[0049] This application provides a binary tree-based topology identification method, which solves the problem that in the past, when the distribution network topology was complex, it was necessary to manually divide fault zones or use complex calculations to identify fault sections. It is specifically designed for distribution network ranging systems.

[0050] As shown in Figure 1, Embodiment 1 of this application provides a method for topology identification of a distribution network ranging terminal, including the following steps:

[0051] Step 1: Generate a binary tree based on the distribution network topology; use towers, ranging terminals, and boundary switches as nodes in the binary tree;

[0052] In a preferred but non-limiting embodiment, step 1 specifically includes:

[0053] Using towers, ranging terminals, and boundary switches as binary tree nodes, binary tree node information is generated based on distribution network topology information. The node information includes: line length L to the left and right child nodes, normalized length LN, node name, child node name, type, and wave velocity s.

[0054] It is worth noting that the wave velocities of the lines at the two ends of a node that lacks ranging information may differ, necessitating the normalization of the lengths for easier calculation, as expressed by the following formula:

[0055] In the formula:

[0056] LN represents the normalized length.

[0057] L represents the length of the line to the left and right child nodes.

[0058] s1 represents the wave velocity of the first segment of the line, s n This indicates the wave velocity of line n.

[0059] Normalize the lengths of the lines at both ends of a node and scale the lengths of all lines connected to a node proportionally to the wave speed.

[0060] Node information is preferred, but not limited to, being entered all at once during the main station modeling. It is worth noting that the binary tree structure will not change if the primary equipment remains unchanged. Changes in the opening and closing of switches do not affect the traversal of the binary tree to find faulty sections.

[0061] In an exemplary but non-limiting implementation, as illustrated in the field topology diagram in Figure 2, when the master station is modeling, the data for each node is entered into the database in the following format. This step can be performed by on-site personnel.

[0062] Node 1 data: Name: FS11; Child node 1 name: node1;

[0063] Node 2 data: Name: node1; Child node 1 name: FS21; Child node 2 name: FS12, distance; Child node 3: FS31

[0064] Node 3 data: Name: FS21; Child node 1 name: LSW2

[0065] Node 4 data: Name: LSW2; Child node 1 name: LSW2;

[0066] Node 5 data: Name: FS22; Child node 1: NONE;

[0067] Node 6 data: Name: FS12; Child node 1: node2;

[0068] ...

[0069] The child node data includes information such as name, distance, and wave speed.

[0070] Furthermore, a binary tree linked list is automatically generated based on the node information. Each node in the binary tree linked list contains the following elements:

[0071] Parent points to the parent node, and the first end of the line is none;

[0072] Child-left points to the child node, and the end of the line is none;

[0073] Child-right points to a child node or sibling node. It is none if there is no T-connection. When there is a 3-terminal T-connection, it points to the child node of the T-connection. If there are multiple 3-terminal T-connections, multiple sibling nodes need to be added. The sibling node name is the same as the original node, and the suffix is ​​added with two underscores and numbers to distinguish it from ordinary node names, such as node1__1, node__2, etc. If the node names before the double underscores are the same, the program will treat them as the same node.

[0074] Name, node name, can correspond to pole number or switch number. When there are multiple sibling T nodes, the node name is distinguished by adding double underscores "__".

[0075] DeviceID, the node terminal number, corresponds to the DeviceID number of the terminal waveform. It is none when the node has no terminal.

[0076] Size_signal, the node signal strength.

[0077] The distance from Distance-left and Distance-right to the next level node;

[0078] Speed-left, Speed-right to the next level node wave speed;

[0079] The normalized distance left and normalized distance right are the distances from the normalized distance to the next level node, which are the normalized distances from the first node's line.

[0080] For ring network lines, when generating a binary tree, the substation side is the starting point or the end point. After generating a binary tree with one end as the starting point and the other end as the ending point, there is no need to generate a binary tree at the other end.

[0081] Step 2: When a fault occurs, the received traveling wavefront time is stored in the node information. The wavefront times are sorted to find the earliest terminal as the reference terminal Tj. The fault point is upstream or downstream of the reference terminal. The binary tree is traversed upstream and downstream respectively to find the effective terminal Tn directly adjacent to the reference terminal. The wavefront time difference Δtn between Tn and the reference terminal is calculated, where n is the effective terminal number.

[0082] It is worth noting that, as one of the prominent substantive features of this application, it uses the wavefront time as the fault time, taking the node with the earliest wavefront time as the reference node. Starting from the reference node, it searches for effective ranging terminals directly connected to it. Nodes not directly connected do not need to participate in the calculation, nor does it require traversing the entire binary tree; only the binary tree needs to be traversed upstream and downstream from the reference node. When the fault point is located in the region of node T, the fault point region is finally determined based on the ranging results of the reference terminal and the effective terminals. The significant improvements resulting from this include: ranging with the reference terminal and multiple effective terminals is suitable for complex multi-branch scenarios with low computational load; and positioning accuracy is higher when using the wavefront time.

[0083] Step 3: The effective segment is defined as the segment whose wavefront time difference Δtn between each effective terminal Tn and the reference terminal Tj is less than the normalized length between the effective terminal and the reference terminal. If the effective segment is greater than 1 segment, it indicates that there is a fault in the T-connected line.

[0084] It is worth noting that, as one of the prominent substantive features of this application, as mentioned above, the opening and closing of the switch does not affect the traversal of the binary tree to find the faulty segment. This is because traveling waves cannot be transmitted when the switch is open. As shown in Figure 3, when the boundary switch LSW2 between FS21 and FS22 is open, one of FS21 and FS22 will not have a traveling wave signal, or even if there is a traveling wave signal, the time difference Δtn between the wavefronts of the two terminals multiplied by the wave velocity is greater than the normalized length between the effective terminal and the reference terminal. Therefore, it will be identified as an invalid segment and will not participate in the ranging.

[0085] Building upon this, as one of the significant advancements achieved in this application, a binary tree algorithm is used for topology identification to locate the faulty section and perform distance measurement. This algorithm can adapt to topology changes caused by changes in switch position, and it requires less computation and is easy to implement.

[0086] Step 4: Calculate the distance to the fault point in each effective section according to the two-end distance measurement formula. If there is only one effective section, the direct output result will be given. If there are multiple effective sections, all the results of the sections are near the T-connection, and the fault point is located at the T-connection. If one section result is not near the T-connection, and the results of the other sections are near the T-connection, the fault point is in the section that is not near the T-connection.

[0087] Step 5: Convert the result calculated in Step 4 back to the distance before normalization and locate it on the tower.

[0088] It is worth noting that this application addresses the issue that the two ends of the intermediate connection point may be overhead lines and cables, respectively, resulting in inconsistent wave velocities. Therefore, the length needs to be normalized, and after locating the fault point, the original length needs to be restored based on the wave velocity of that section. If the location of the switch is not intuitive for on-site users locating the fault point, the output will first locate the nearest pole number, reporting the nearest pole number and the distance to that pole.

[0089] Embodiment 2 of this application provides a system for topology identification of distribution network ranging terminals, which implements the method for topology identification and ranging of distribution network terminals described in Embodiment 1, including:

[0090] The binary tree generation module is used to generate binary trees based on the distribution network topology data;

[0091] The lookup module is used to locate the baseline terminal Tj and the valid terminal Tn in the event of a fault.

[0092] The ranging module calculates the effective segment based on the node information of the reference terminal Tj and the effective terminal Tn, and calculates the distance to the fault point within the effective segment.

[0093] To more clearly illustrate the outstanding substantive features of this application and the significant progress it brings to the prior art, the technical solution of this application is illustrated by an example below.

[0094] Distance measurement processing:

[0095] After collecting waveforms from each terminal, the terminal (node) that first receives the traveling wave is found. The fault point is near the node that first receives the wave. The branches near this node are searched. For example, if a fault occurs between node1 and FS12 in Figure 2, node FS12 will receive the traveling wave signal first. Using FS12 as the reference node, the nodes with the wavefront that are directly connected to FS12 are searched for to perform two-end distance measurement. In specific use, binary tree related library functions such as treelib functions can be called to reduce programming workload and improve efficiency.

[0096] The search results are shown in Figure 4 below.

[0097] Path results towards parent node

[0098] Segment 1: FS12-node1-FS21 intermediate node node1

[0099] Segment 2: FS12-node1-FS11 intermediate node node1

[0100] Segment 3: FS12-node1-FS31 intermediate node node1

[0101] The above three sections

[0102] Path results towards child nodes

[0103] Segment 4: FS12-node2-FS13 intermediate node node2

[0104] Segment 5: FS12-node2-FS41 intermediate node node2

[0105] The result includes the total path length, intermediate node locations, and other information. Follow these steps to perform the calculation.

[0106] The distance is calculated based on the time difference between the first and last terminals of the path. If the distance is less than the path length, it means that the fault point is within the path range and the distance can be measured using the two-end method; otherwise, the path is excluded.

[0107] Calculate using all the paths selected in step 1. If all path results are at a fixed distance from the baseline node, or if the distance measurement result is correct at the same intermediate node.

[0108] If the wavefront time difference of segments 3 and 4 multiplied by the wave velocity is greater than or equal to the normalized length of the segment, it is not a fault segment and will no longer be used for ranging.

[0109] If the wavefront time difference multiplied by the wave velocity is less than the normalized length of this segment, it is a faulty segment. The calculation result for segment 1 is node1, the calculation result for segment 2 is node1, the calculation result for segment 4 is node1, and the calculation result for segment 3 is between node1 and FS21. Finally, the result for segment 3 is output.

[0110] By adopting the above scheme, this application can achieve rapid and accurate topology identification with very little computational effort, without the need for manual intervention, thus reducing workload and facilitating the promotion of traveling wave ranging in distribution networks.

[0111] In practice, a binary tree can be replaced with a regular tree or other methods.

[0112] The advantages of binary trees compared to other methods include at least the following:

[0113] 1. Simple Structure: A binary tree is the simplest tree structure, with each node having at most two child nodes. This structure makes it simpler and clearer to implement and operate. Compared to other tree structures, such as multi-way trees or balanced trees, the construction and operation of binary trees are more intuitive and easier to understand.

[0114] 2. Fast Search: Binary trees offer extremely high search efficiency. Due to the properties of binary trees, a balanced binary tree with n nodes requires at most log(n) comparisons to find the target node. This efficient search performance makes binary trees ideal for fast searching and retrieval.

[0115] 3. Facilitates Sorting: A binary search tree (BST) is a special type of binary tree where the value of the left child node is less than or equal to the value of the current node, and the value of the right child node is greater than or equal to the value of the current node. This property makes BSTs very suitable for sorting algorithms, allowing for easy implementation of quicksort, inorder traversal, and more.

[0116] 4. Simplified Operations: The structure and properties of binary trees make operations such as insertion, deletion, and modification more efficient. Compared to other more complex tree structures, binary tree operations are easier to implement and understand. These basic operations can be performed efficiently on binary trees, making them an ideal choice for many algorithm and data structure applications.

[0117] 5. Wide Range of Applications: Binary trees have numerous applications in computer science, such as database indexing, Huffman coding, image processing, and compilers. These applications require efficient data structures and algorithms, and binary trees can effectively solve various problems and are widely used in the fields of algorithms and data structures. Whether it's basic sorting and searching operations or more complex computational and data processing tasks, binary trees play a vital role.

[0118] In summary, binary trees are widely used in computer science due to their simple structure, fast search, convenient sorting, simplified operation, and wide application.

[0119] Besides tree structures, there are also linked lists and star structures, which are slightly less efficient than tree structures when used for distribution network topology identification.

[0120] Compared with the prior art, this application discloses a method for topology identification and ranging of distribution network terminals. This method generates a binary tree based on data such as towers, switches, and lines. After a line fault occurs, the reference terminal and effective terminal are determined based on the wavefront time data. Then, the binary tree algorithm is used to identify the topology, locate the fault section, and perform ranging. It can adapt to the topology changes caused by the change of switch position, and has a small computational load and is easy to implement.

[0121] This application uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for topology identification and ranging of distribution network terminals, wherein, Includes the following steps: Step 1: Generate a binary tree based on the distribution network topology data, with towers, ranging terminals, and boundary switches as nodes in the binary tree, and input the node information; Step 2: When a fault occurs, take the ranging terminal that first measured the traveling wave front as the reference terminal Tj, traverse the binary tree around the reference terminal to find the valid terminal Tn, and calculate the wave front time difference Δtn between it and the reference terminal, where n is the valid terminal number. Step 3: The effective segment is the segment whose wavefront time difference Δtn between each effective terminal Tn and the reference terminal Tj is less than the length between the effective terminal and the reference terminal. as well as Step 4: Calculate the distance to the fault point within the effective section using the two-end distance measurement formula.

2. The method for topology identification and ranging of a distribution network terminal as described in claim 1, wherein: Node information includes: line length L to the left and right child nodes, normalized length LN, node name, child node name, type, and wave velocity s; the normalized length LN is expressed by the following formula: In the formula: LN represents the normalized length. L represents the length of the line to the left and right child nodes. s1 represents the wave velocity of the first segment of the line, s n This indicates the wave velocity of line n.

3. The method for topology identification and ranging of a distribution network terminal as described in claim 2, wherein: A binary tree linked list is automatically generated based on the node information. Each node in the binary tree linked list contains the following elements: Parent points to the parent node, and the first end of the line is none; Child-left points to the child node, and the end of the line is none; Child-right points to a child node or a sibling node; Name, the node name, corresponds to the pole number or switch number; DeviceID, the node terminal number, corresponds to the DeviceID number of the terminal waveform. It is none when the node has no terminal. Size_signal, node signal strength; The distance from Distance-left and Distance-right to the next level node; Speed-left, Speed-right to the next level node wave speed; as well as The normalized distance left and normalized distance right are the distances from the normalized distance to the next level node, which are the normalized distances from the first node's line.

4. The method for topology identification and ranging of a distribution network terminal as described in claim 3, wherein: Child-right, pointing to a child node or sibling node, specifically includes: none if there is no T-connection; pointing to the child node of the T-connection when there are multiple T-connections; if there are multiple T-connections, multiple sibling nodes need to be added. The sibling node name is the same as the original node, but is distinguished from the ordinary node name by adding two underscores and numbers to the suffix; and Name, the node name specifically includes: when there are multiple sibling T nodes, the node name is distinguished by adding double underscores "__".

5. A method for topology identification and ranging of distribution network terminals as described in any one of claims 2 to 4, wherein: For ring network lines, when generating a binary tree, the substation side is the starting point or the end point. After generating a binary tree with one end as the starting point and the other end as the ending point, there is no need to generate a binary tree at the other end.

6. The method for topology identification and ranging of a distribution network terminal as described in claim 2, wherein: In step 2, when a fault occurs, the received traveling wave head time is stored in the node information. The wave head times are sorted to find the earliest terminal as the reference terminal Tj. The fault point is upstream or downstream of the reference terminal. The binary tree is traversed upstream and downstream respectively to find the effective terminal Tn directly adjacent to the reference terminal.

7. The method for topology identification and ranging of a distribution network terminal as described in claim 2, wherein: In step 3, if the effective segment is 1 segment, the fault point is located within the effective segment; if the effective segment is greater than 1 segment, the fault has occurred in the T-connected line.

8. The method for topology identification and ranging of a distribution network terminal as described in claim 7, wherein: In step 4, the distance to the fault point in each effective section is calculated according to the two-end method distance measurement formula. If there is only one effective section, the direct output result is obtained. If there are multiple effective sections, all the section results are near the T-connection, and the fault point is located at the T-connection. If one section result is not near the T-connection, and the results of other sections are near the T-connection, the fault point is in the section that is not near the T-connection.

9. A method for topology identification and ranging of a distribution network terminal as described in any one of claims 6 to 8, wherein: The method further includes: Step 5: Convert the result calculated in Step 4 back to the distance before normalization and locate it on the tower.

10. A system for topology identification of distribution network ranging terminals, comprising the method for topology identification and ranging of distribution network terminals as described in any one of claims 1-9, wherein, include: The binary tree generation module is configured to generate a binary tree based on the distribution network topology data; The lookup module is configured to look up the baseline terminal Tj and the valid terminal Tn when a fault occurs. The ranging module is configured to calculate the effective segment based on the node information of the reference terminal Tj and the effective terminal Tn, and to calculate the distance to the fault point within the effective segment.

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