A method, device and computer program product for identifying a key path of a metro stray current intrusion into a substation

Abstract

The application discloses a metro stray current invasion substation key path identification method and device and a computer program product, and relates to the technical field of urban rail transit stray current protection. In order to solve the problem that the traditional stray current path identification method has large calculation amount, depends on field measurement, and does not fully combine network topology and conduction medium characteristics, leading to the difficulty of meeting the large-scale network demand in identification efficiency and accuracy, the application obtains the spatial distribution information and electrical impedance parameters of the metro system and the urban power grid, constructs a weighted complex network model of the coupling of the metro and the power grid through the conduction medium, calculates the topological importance index of each edge based on the network shortest path, and then screens the key path of the stray current invasion substation. The application does not need to depend on real-time train operation data and large-scale field measurement, can efficiently and accurately identify the key conduction path, provides technical support for stray current protection and operation and maintenance planning, and improves the safe and stable operation level of the urban power system.

Description

Technical Field

[0001] This invention relates to the field of stray current protection in subways and safety protection technology for urban substations, specifically to a method, device, and computer program product for identifying critical paths of stray current intrusion into substations from subways. Background Technology

[0002] With the rapid development of urban rail transit systems, stray current problems in DC-powered subway systems are becoming increasingly prominent. These stray currents mainly originate from subway traction current leaking from the rails into the soil and further into the urban AC power grid, causing a series of safety and equipment problems. Stray currents can lead to DC bias magnetization at the neutral point of power transformers, increasing transformer vibration and noise, accelerating insulation aging, and reducing equipment lifespan. Furthermore, buried metal structures such as pipes, tunnel linings, and power cables are prone to corrosion under long-term exposure to stray currents, posing safety hazards to urban infrastructure. Traditional stray current intrusion path analysis methods, including the finite element method, boundary element method, and experimental measurement methods, while providing detailed current distribution information, often suffer from massive computational loads, difficulties in on-site measurement, and high costs, making real-time and comprehensive analysis difficult in large-scale urban rail systems.

[0003] While existing analytical and resistive network models are widely used in engineering, they have limitations. Analytical models typically treat subway tracks as parallel conductors, neglecting complex network topologies and soil heterogeneity, leading to significant prediction errors. Resistive network models, although capable of calculating branch currents, rely solely on current amplitude to identify critical paths, failing to adequately consider the significant impact of network topology and material properties on stray current conduction. Furthermore, with the continuous expansion of urban rail lines, traditional methods struggle to meet engineering requirements in terms of computational efficiency and real-time performance. These issues limit the targetedness and effectiveness of stray current protection measures, easily resulting in resource waste and potential risks. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method, device and computer program product for identifying the critical path of stray current intrusion into a substation in a subway, so as to realize the rapid assessment and critical path identification of large-scale complex networks, and provide a reliable basis for stray current protection of subways and urban substations.

[0005] To address the aforementioned technical problems, this invention provides a method for identifying the critical path of stray current intrusion into a substation in a subway system, comprising: Step S1: Obtain topology basic data, which includes spatial distribution information of the subway system and urban power grid, as well as electrical impedance parameters of stray current conduction paths; Step S2: Abstract the electrical facilities in the subway system and the urban power grid as network nodes, and the stray current conduction path as the connection between nodes. Use the electrical impedance parameter as the weight of the connection to construct a weighted complex network model of the subway and the power grid coupled through the conduction medium. Step S3: Calculate the topological importance index of each edge in the weighted complex network based on the shortest path of the network. The topological importance index is used to characterize the importance of the corresponding edge in the process of stray current being conducted from the subway system to the urban power grid substation. Step S4: Based on the topological importance index, each connection edge is screened to obtain the critical path for stray current from the subway to intrude into the urban substation.

[0006] Preferably, the weighted complex network model is a three-layer coupled network of subway-power grid-soil, including a subway subnetwork, a power grid subnetwork and a soil subnetwork; there are coupling edges between the subway subnetwork and the soil subnetwork, and between the power grid subnetwork and the soil subnetwork, and there is a direct electrical connection edge between the subway subnetwork and the power grid subnetwork.

[0007] Preferably, the nodes of the metro subnetwork are metro nodes abstracted from metro stations and depots, and the metro subnetwork is a linear chain network; the nodes of the power grid subnetwork are power grid nodes abstracted from urban power grid substations, and the power grid subnetwork is a mesh network; the nodes of the soil subnetwork are soil nodes arranged in a grid distribution, and the soil subnetwork is a mesh network.

[0008] Preferably, the weight of each edge in the weighted complex network is calculated and determined based on the DC resistivity of the material of the corresponding conduction path, the path length, and the effective conductive cross-sectional area.

[0009] Preferably, the topological importance indicators include edge betweenness centrality, edge fragility, and path importance; The edge betweenness centrality characterizes the proportion of edges carried in the shortest path of global node pairs in the network. The edge vulnerability characterizes the degree of change in the overall network transmission efficiency after removing the corresponding edge. The path importance characterizes the proportion of the load on the shortest path from the subway node to the power grid node.

[0010] Preferably, step S4 specifically includes: The edge betweenness centrality, edge fragility, and path importance are normalized to map each index to the same numerical range. The three normalized indicators are weighted and summed according to the preset weight coefficients to obtain the basic score of each edge. Based on the aforementioned basic score, each connection is filtered to obtain the critical path for stray current from the subway to intrude into the urban substation.

[0011] Preferably, step S4 further includes: The basic score is corrected based on the conductive medium properties corresponding to the connection edge to obtain the comprehensive score of each connection edge. Edges with a comprehensive score higher than a preset score threshold are identified as critical paths for stray currents from the subway to intrude into urban substations.

[0012] Preferably, the sum of the preset weighting coefficients is 1; the correction rule for the conductive medium property is: when the connection corresponds to a metal conduction path, the correction coefficient is 2.0, and when the connection corresponds to a soil conduction path, the correction coefficient is 1.0; the preset scoring threshold is 0.7.

[0013] The present invention also provides a device for identifying the critical path of stray current intrusion into a substation in a subway, comprising: One or more processors; Memory; One or more applications, wherein the one or more applications are stored in the memory and configured to be executed by the one or more processors, the one or more applications being configured to perform the metro stray current intrusion substation critical path identification method.

[0014] The present invention also provides a computer program product, including computer instructions, which instruct a computer device to perform operations corresponding to the method for identifying the critical path of stray current intrusion into a subway substation.

[0015] The beneficial effects of this invention are as follows: It does not rely on real-time train operation data or large-scale field measurements. Based solely on the spatial distribution and electrical connections between the subway and the power grid, it constructs a coupled weighted complex network model. This model combines multi-dimensional topological indicators such as betweenness centrality and path importance with a comprehensive weighted evaluation method, while also considering the preferential conductivity of metallic paths. This allows for the efficient and accurate identification of critical conduction paths for stray currents from the subway into urban substations. This invention effectively overcomes the shortcomings of traditional methods, such as high computational load, poor adaptability, and insufficient consideration of network topology and material conduction characteristics. It enables rapid evaluation of large-scale, complex subway-power grid coupled systems, providing a reliable technical basis for stray current protection scheme development, real-time monitoring, and operation and maintenance planning. Applying this invention can specifically improve the safety and reliability of subway power supply systems, delay insulation aging of power equipment, extend equipment lifespan, reduce the risk of corrosion and operation and maintenance costs of urban infrastructure, and overall improve the safe and stable operation level of the urban power system. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating a method for identifying critical paths of stray current intrusion into a substation in an embodiment of the present invention.

[0018] Figure 2 This is a diagram of the subway-electric power grid coupling structure in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of a complex network model of a subway-power grid substation in an embodiment of the present invention. Detailed Implementation

[0020] The following description of the embodiments is taken with reference to the accompanying drawings, which illustrate specific embodiments in which the invention can be implemented.

[0021] Please refer to Figure 1 As shown, Embodiment 1 of the present invention provides a method for identifying the critical path of stray current intrusion into a substation in a subway, comprising: Step S1: Obtain topology basic data, which includes spatial distribution information of the subway system and urban power grid, as well as electrical impedance parameters of stray current conduction paths; Step S2: Abstract the electrical facilities in the subway system and the urban power grid as network nodes, and the stray current conduction path as the connection between nodes. Use the electrical impedance parameter as the weight of the connection to construct a weighted complex network model of the subway and the power grid coupled through the conduction medium. Step S3: Calculate the topological importance index of each edge in the weighted complex network based on the shortest path of the network. The topological importance index is used to characterize the importance of the corresponding edge in the process of stray current being conducted from the subway system to the urban power grid substation. Step S4: Based on the topological importance index, each connection edge is screened to obtain the critical path for stray current from the subway to intrude into the urban substation.

[0022] The steps of the method in this embodiment will be described in detail below.

[0023] Step S1 is used to obtain basic topology data, namely, to obtain the spatial distribution information and electrical impedance parameters required for network modeling, which serve as the data foundation for subsequent model construction and path calculation. The basic topology data specifically includes: Spatial distribution information collection: Through geographic information systems, engineering design drawings and on-site surveys, collect geographic location data of the subway system and urban power grid, including coordinate information of subway stations, depots and traction substations, as well as spatial coordinates and directions of substations and transmission lines of the urban AC power grid.

[0024] Electrical impedance parameter acquisition: Collect electrical parameters of various stray current conduction paths, including the DC resistivity and total cross-sectional area of ​​subway rails, the resistivity and cross-sectional area of ​​cable armor, the resistivity and cross-sectional area of ​​power grid transmission lines and overhead ground wires, and the DC resistivity distribution data of the soil; at the same time, collect the rail-to-ground transition resistance and grounding resistance values ​​of subway stations and depots, as well as the grounding resistance values ​​of various power grid substations.

[0025] Step S2 is used to construct a weighted complex network model of the subway and power grid coupled through a conductive medium. Based on the acquired topological data, a three-layer coupled weighted complex network model is established through node abstraction, subnetwork construction, and coupling connections. The subway-power grid coupled physical topology in this embodiment can be referred to... Figure 2 As shown: The subway side includes stations 1 to 5 arranged sequentially along the line, and each station is connected in series by steel rails to form a subway transmission path; the power grid side includes substation 1, substation 2, and substation 3, and each substation is connected by transmission lines to form a mesh power grid topology; among them, station 2 and substation 1, and station 4 and substation 3 are directly electrically coupled by cable armor respectively.

[0026] Based on the above physical topology, a weighted complex network model is constructed as follows: Step S21, network node abstraction.

[0027] The subway system and various electrical facilities in the urban power grid are abstracted as corresponding network nodes: each subway station and depot is abstracted as a subway node, forming a set of subway nodes. Abstracting each substation in the urban power grid into a power grid node constitutes a set of power grid nodes. Based on the soil resistivity distribution, soil nodes are arranged in a grid pattern within the region to form a soil node set. The grid spacing of the soil nodes can be set according to the required identification accuracy. In this preferred embodiment, a uniform grid with a spacing of 500m is used in the urban area.

[0028] Step S22: Subnetwork construction and edge weight calculation.

[0029] Sub-networks for subway, power grid, and soil are constructed separately. The weights of the edges connecting nodes in each sub-network are based on the DC impedance of the conduction path, and the formula for calculating the edge weights is unified as follows:

[0030] in, The DC resistivity of the conductive path material. The length of the conduction path, It represents the effective conductive cross-sectional area of ​​the conduction path.

[0031] Subway subnetwork: The subway line is abstracted as a linear chain network. Adjacent subway nodes are connected by rail transmission paths. The edge weights are calculated based on the rail resistivity, station spacing and total rail cross-sectional area using the above formula.

[0032] Power Grid Subnetwork: The urban power grid is abstracted as a mesh network. Adjacent power grid nodes are connected through transmission lines, overhead ground wires, or cable armored conduction paths. The edge weights are calculated using the formula above based on the resistivity, line length, and conductive cross-sectional area of ​​the corresponding conduction path.

[0033] Soil subnetwork: The edge weights between adjacent soil nodes are calculated using the above formula based on the soil resistivity and node spacing of the corresponding region.

[0034] Step S23: Establish direct connection edges and coupled edges.

[0035] Direct connection edge: If there is a direct electrical connection such as cable armor between the subway station and the power grid substation, a direct connection edge is established between the corresponding subway node and the power grid node. The edge weight is calculated based on the resistivity of the cable armor, the cable length, and the cross-sectional area of ​​the armor.

[0036] Coupling edges: Based on spatial proximity, coupling edges are established between metro nodes and corresponding soil nodes, and between power grid nodes and corresponding soil nodes. The weight of the coupling edge between metro nodes and soil nodes is the sum of the rail-to-ground transition resistance and grounding resistance of the corresponding metro station / depot, and the weight of the coupling edge between power grid nodes and soil nodes is the grounding resistance value of the strain gauge substation.

[0037] Step S24, network model integration.

[0038] Integrating the aforementioned subway subnetwork, power grid subnetwork, soil subnetwork, and all coupled and directly connected edges, we obtain a weighted complex network model with three layers of coupling between the subway, power grid, and soil. Its overall architecture is as follows: Figure 3 As shown: the upper layer is a mesh-structured power grid subnetwork, the middle layer is a linear chain-structured subway subnetwork, and the lower layer is a grid-structured soil subnetwork; there are direct electrical connection edges between the subway subnetwork and the power grid subnetwork, and the subway subnetwork and the power grid subnetwork are connected to the soil subnetwork through coupling edges, together forming a stray current coupling and conduction network.

[0039] The integrated network model is denoted as:

[0040] in, This represents a linear chain network of the subway system. For the set of subway nodes, This is a set of edges connecting subway nodes. This is the set of weights for the corresponding connected edges; Represents a mesh subnetwork of the power grid. For the set of power grid nodes, This is the set of edges connecting nodes in the power grid. This is the set of weights for the corresponding connected edges; Represents a soil grid subnetwork. For the set of soil nodes, This is the set of edges connecting soil nodes. This is the set of weights for the corresponding connected edges; This represents the set of all coupled edges and directly connected edges.

[0041] Step S3 is used to calculate the topological importance index of each edge, that is, based on the shortest path in the network, to calculate the topological importance index of each edge in the weighted complex network, so as to quantify the importance of each edge in the stray current conduction process. In this embodiment, the topological importance index specifically includes three categories: edge betweenness centrality, edge vulnerability, and path importance. The calculation process is as follows: (1) Calculation of edge betweenness centrality Edge betweenness centrality ( This is used to characterize the proportion of edges carried in the global shortest path of the network, reflecting the global importance of edges in the entire network propagation. The calculation formula is:

[0042] in, For nodes and The total number of shortest paths between them. For nodes and Connecting edges The number of shortest paths, It is the set of all nodes in the network.

[0043] (2) Edge vulnerability ( )calculate Edge vulnerability is used to characterize the degree of decrease in the overall transmission efficiency of the network after the removal of the corresponding edge, reflecting the impact of the edge on the robustness of the network structure.

[0044] First, calculate the network efficiency. :

[0045] in, The number of nodes in the network; For nodes and The shortest path length between them is calculated using Dijkstra's shortest path algorithm.

[0046] Furthermore, connecting the edges Edge fragility is defined as the difference in network efficiency before and after removing the edge:

[0047] in, Indicates removing the edge. The network after that.

[0048] (3) Importance of the path ( )calculate Path importance is used to characterize the proportion of load carried by the connection in the directional transmission path from the subway node to the power grid node, directly reflecting the role of the connection in the process of stray current entering the power grid from the subway. The calculation formula is as follows:

[0049] in, It is a set of subway nodes (station nodes and depot nodes). This is a set of power grid nodes (substation nodes).

[0050] Step S4 is used to screen out the critical paths of stray current intrusion. That is, based on the calculated topological importance index, the critical paths of stray current intrusion into the substation are identified through multi-index weighted fusion and threshold screening. The specific process is as follows: First, index normalization is performed: The three indices—edge betweenness centrality, edge fragility, and path importance—are normalized, mapping their values ​​to the [0,1] interval to eliminate dimensional differences. This embodiment uses linear normalization for any index. Normalized value for:

[0051] in, This is the maximum value of the index among all connected edges. This is the minimum value of the index among all connected edges.

[0052] Next, a comprehensive score will be calculated: First, obtain the basic score of each edge by weighted summation:

[0053] in, The normalized edge betweenness centrality; The normalized edge fragility; The normalized path importance; , , The weighting coefficients for the three types of indicators satisfy the following conditions: + + =1; In this embodiment, it can be selected =0.3, =0.25, =0.45.

[0054] Then, based on the conductive dielectric properties of the connection, a metal path factor is introduced to correct the basic score, resulting in a comprehensive score for the connection:

[0055] in, This is the metal path factor; if the edge corresponds to a metal conduction path (such as a rail, cable armor, transmission line, etc.), then it is taken as... =2.0; if the connected edge corresponds to a soil conduction path, then take 2.0. =1.0.

[0056] Finally, threshold filtering is performed.

[0057] A preset scoring threshold is used to identify edges with a comprehensive score higher than the threshold as critical paths for stray current from the subway into the urban substation. In this embodiment, the threshold is set to 0.7, which is the comprehensive score. Edges with a value >0.7 are considered critical paths.

[0058] As can be seen from the above description, this embodiment constructs a weighted complex network model with three layers of coupling between the subway, power grid, and soil. It comprehensively evaluates the network by combining three dimensions of indicators: global topology characteristics, structural robustness, and directional transmission effect. Without the need for large-scale finite element calculations and point-by-point on-site measurements, it can efficiently and accurately identify the key transmission paths of stray current intrusion into the substation, and can provide data support for the formulation of subsequent stray current protection schemes.

[0059] Corresponding to the method for identifying the critical path of stray current intrusion into a substation in Embodiment 1 of the present invention, Embodiment 2 of the present invention also provides a device for identifying the critical path of stray current intrusion into a substation in a subway, comprising: One or more processors; Memory; One or more applications, wherein the one or more applications are stored in the memory and configured to be executed by the one or more processors, the one or more applications being configured to perform the metro stray current intrusion substation critical path identification method.

[0060] Corresponding to the method for identifying the critical path of stray current intrusion into a substation in Embodiment 1 of the present invention, Embodiment 3 of the present invention also provides a computer program product, including computer instructions, which instruct computer equipment to perform the operation corresponding to the method for identifying the critical path of stray current intrusion into a substation in the subway.

[0061] Preferably, 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. The general-purpose processor can be a microprocessor, or the processor can be any conventional processor. The processor is the control center of the device, connecting various parts of the device through various interfaces and lines.

[0062] The memory mainly includes a program storage area and a data storage area. The program storage area can store the operating system, applications required for at least one function, etc., while the data storage area can store related data, etc. Furthermore, the memory can be a high-speed random access memory, or a non-volatile memory, such as a plug-in hard drive, a SmartMedia Card (SMC), a Secure Digital (SD) card, and a Flash Card, or other volatile solid-state storage devices.

[0063] It should be noted that the above-mentioned devices may include, but are not limited to, processors and memory, as will be understood by those skilled in the art.

[0064] For the working principle and process of the above embodiments, please refer to the description of Embodiment 1 of the present invention, which will not be repeated here.

[0065] Compared with existing technologies, this invention has the following significant advantages: This invention does not rely on real-time train operation data or large-scale field measurements. Based solely on the spatial distribution and electrical connections between the subway and the power grid, it constructs a coupled weighted complex network model. Combining multi-dimensional topological indicators such as betweenness centrality and path importance with a comprehensive weighted evaluation method, and taking into account the preferential conductivity of metallic paths, it can efficiently and accurately identify the key conduction paths of stray currents from the subway into urban substations. This invention effectively overcomes the shortcomings of traditional methods, such as high computational load, poor adaptability, and insufficient consideration of network topology and material conduction characteristics. It enables rapid evaluation of large-scale complex subway-power grid coupled systems, providing a reliable technical basis for stray current protection scheme formulation, real-time monitoring, and operation and maintenance planning. Applying this invention can specifically improve the safety and reliability of subway power supply systems, delay insulation aging of power equipment, extend equipment lifespan, reduce the risk of corrosion and operation and maintenance costs of urban infrastructure, and overall improve the safe and stable operation level of the urban power system.

[0066] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for identifying critical paths of stray current intrusion into a substation in a subway system, characterized in that, include: Obtain topology data, which includes spatial distribution information of the subway system and urban power grid, as well as electrical impedance parameters of stray current conduction paths; The electrical facilities in the subway system and the urban power grid are abstracted as network nodes, and the stray current conduction paths are abstracted as the edges between nodes. The electrical impedance parameters are used as the weights of the edges to construct a weighted complex network model of the subway and the power grid coupled through the conduction medium. The topological importance index of each edge in the weighted complex network is calculated based on the shortest path in the network. The topological importance index is used to characterize the importance of the corresponding edge in the process of stray current being conducted from the subway system to the urban power grid substation. Based on the aforementioned topological importance index, each connection is screened to obtain the critical path for stray current from the subway to intrude into the urban substation.

2. The method according to claim 1, characterized in that, The weighted complex network model is a three-layer coupled network of subway-power grid-soil, including a subway subnetwork, a power grid subnetwork and a soil subnetwork; there are coupling edges between the subway subnetwork and the soil subnetwork, and between the power grid subnetwork and the soil subnetwork, and there is a direct electrical connection edge between the subway subnetwork and the power grid subnetwork.

3. The method according to claim 2, characterized in that, The nodes of the metro subnetwork are metro nodes abstracted from metro stations and depots, and the metro subnetwork is a linear chain network; the nodes of the power grid subnetwork are power grid nodes abstracted from urban power grid substations, and the power grid subnetwork is a mesh network; the nodes of the soil subnetwork are soil nodes arranged in a grid distribution, and the soil subnetwork is a mesh network.

4. The method according to claim 2, characterized in that, The weights of each edge in the weighted complex network are calculated and determined based on the DC resistivity of the material of the corresponding conduction path, the path length, and the effective conductive cross-sectional area.

5. The method according to claim 1, characterized in that, The topological importance metrics include edge betweenness centrality, edge fragility, and path importance. The edge betweenness centrality characterizes the proportion of edges carried in the shortest path of global node pairs in the network. The edge vulnerability characterizes the degree of change in the overall network transmission efficiency after removing the corresponding edge. The path importance characterizes the proportion of the load on the shortest path from the subway node to the power grid node.

6. The method according to claim 5, characterized in that, Step S4 specifically includes: The edge betweenness centrality, edge fragility, and path importance are normalized to map each index to the same numerical range. The three normalized indicators are weighted and summed according to the preset weight coefficients to obtain the basic score of each edge. Based on the aforementioned basic score, each connection is filtered to obtain the critical path for stray current from the subway to intrude into the urban substation.

7. The method according to claim 6, characterized in that, Step S4 further includes: The basic score is corrected based on the conductive medium properties corresponding to the connection edge to obtain the comprehensive score of each connection edge. Edges with a comprehensive score higher than a preset score threshold are identified as critical paths for stray currents from the subway to intrude into urban substations.

8. The method according to claim 7, characterized in that, The sum of the preset weighting coefficients is 1; the correction rule for the conductive medium properties is: when the connection corresponds to a metal conduction path, the correction coefficient is 2.0, and when the connection corresponds to a soil conduction path, the correction coefficient is 1.0; the preset scoring threshold is 0.

7.

9. A device for identifying critical paths of stray current intrusion into a subway substation, characterized in that, include: One or more processors; Memory; One or more applications, wherein the one or more applications are stored in the memory and configured to be executed by the one or more processors, the one or more applications being configured to perform the critical path identification method for stray current intrusion into a metro substation as described in any one of claims 1 to 8.

10. A computer program product, characterized in that, The method includes computer instructions that instruct computer equipment to perform operations corresponding to the critical path identification method for stray current intrusion into a substation as described in any one of claims 1 to 8.

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