Distribution cable insulation defect analysis and diagnosis method, device, equipment and medium

Abstract

The invention relates to a distribution cable insulation defect analysis and diagnosis method, device, equipment and medium, and the method comprises the steps: constructing a three-dimensional finite element model of a distribution cable comprising a copper shielding layer, an insulating layer and a sheath structure; performing electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the distribution cable to obtain a simulation result, simulating current leakage characteristics caused by local damage of the sheath, and generating a fault characteristic library; collecting sheath current information of the power distribution cable body and the joint in real time; calculating multi-parameter residual data according to the sheath current information and a simulation result, and inputting the multi-parameter residual data into a fault judgment model; and when the judgment result of the fault judgment model is that a fault exists, fault analysis is completed based on the fault feature library, and an early warning strategy is generated. The intelligent level and reliability of power distribution network cable operation and maintenance can be improved.

Description

Technical Field

[0001] This invention relates to the field of power distribution cable fault detection technology, and in particular to a method, device, equipment and medium for analyzing and diagnosing insulation defects in power distribution cables. Background Technology

[0002] Cable sheath current detection technology has received widespread attention in recent years as an important means of monitoring the condition of power distribution networks. With the acceleration of urbanization, power cables account for more than 70% of the power distribution network. According to the State Grid's fault statistics report in 2023, faults caused by sheath defects accounted for as much as 43% of these faults.

[0003] Traditional sheath current detection methods mainly suffer from the following technical bottlenecks: (1) Insufficient detection accuracy. Existing technologies mostly use power frequency current transformers (such as Rogowski coils) to measure the effective value of sheath current, and the measurement bandwidth is usually limited to the range of 50Hz-1kHz. This method cannot capture the high-frequency transient components in the sheath current (such as nanosecond-level pulses caused by partial discharge), resulting in an early insulation defect missed rate of up to 35%. (2) Insufficient research on fault mechanisms. Current sheath current analysis mainly relies on the empirical threshold method and lacks quantitative research on the spatial distribution characteristics of current. IEEE Std 400.3-2022 points out that the existing standard has not yet established the correspondence between sheath current density distribution and insulation defect size. Especially in distribution cables, the problem of phase-to-phase current interference caused by electromagnetic coupling effect has not been fully considered for a long time, resulting in errors in fault location, and the fault location error generally exceeds 5 meters. (3) Lack of multi-physics coupling analysis. Abnormal sheath current is often accompanied by temperature field distortion and mechanical stress changes, but most existing detection devices monitor a single electrical parameter. A 2021 CIGRE research report indicated that the fault misjudgment rate without considering the thermo-mechanical coupling effect was 40% higher than that of the comprehensive analysis method. (4) Real-time bottleneck. The traditional finite element simulation method takes 6-8 hours to calculate the sheath current distribution of a 10kV cable, which cannot meet the needs of online monitoring. (5) Incomplete standard system. At present, some standards only specify the limit requirements for sheath circulating current and lack graded early warning indicators for different fault types.

[0004] These technical shortcomings make existing sheath current detection systems insufficient to meet the development needs of smart distribution networks. Especially in high-load-density cities like Shanghai and Shenzhen, 69% of power outages caused by cable faults could have been avoided through more accurate sheath current analysis (data from the 2023 Urban Power Grid Reliability White Paper). Therefore, developing a sheath current analysis and diagnostic technology has significant engineering value. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method, device, equipment and medium for analyzing and diagnosing insulation defects in power distribution cables, which can improve the intelligence level and reliability of power distribution network cable operation and maintenance.

[0006] The technical solution adopted by this invention to solve its technical problem is: to provide a method for analyzing and diagnosing insulation defects in power distribution cables, comprising the following steps:

[0007] Construct a three-dimensional finite element model of a power distribution cable that includes a copper shielding layer, an insulation layer, and a sheath structure;

[0008] An electro-magnetic-thermal coupling simulation was performed on the three-dimensional finite element model of the power distribution cable to obtain simulation results. The current leakage characteristics caused by local damage to the sheath were simulated to generate a fault feature library.

[0009] Real-time acquisition of sheath current information of power distribution cable body and joints;

[0010] Calculate multi-parameter residual data based on the sheath current information and simulation results, and input the multi-parameter residual data into the fault judgment model;

[0011] When the fault diagnosis model determines that a fault exists, fault analysis is performed based on the fault feature library, and an early warning strategy is generated.

[0012] When constructing the three-dimensional finite element model of the power distribution cable including the copper shielding layer, insulation layer and sheath structure, the spatial structure and electromagnetic coupling characteristics of the three-phase conductors, metal shielding layer and insulation material are considered, and the distribution law of sheath current at the cable body and joint is simulated by defining frequency-varying material parameters and nonlinear boundary conditions.

[0013] When performing electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the power distribution cable, the distribution law of sheath current at the cable body and joint is simulated by defining frequency-varying material parameters and nonlinear boundary conditions.

[0014] When collecting real-time sheath current information of the power distribution cable body and joints, a high-frequency sensor array is used to collect sheath current signals with a bandwidth of 0.1Hz-1MHz.

[0015] When judging the multi-parameter residual data, the fault judgment model calculates the ratio of the multi-parameter residual data to the simulation results of the corresponding parameters. If any ratio exceeds a preset value, a fault is judged to exist.

[0016] The fault analysis based on the fault feature library specifically involves: determining the parameter corresponding to the ratio exceeding a preset value, searching the fault feature library according to the characteristics of the parameter, determining the location and type of the fault, and then classifying the fault according to the magnitude of the ratio.

[0017] Before calculating the multi-parameter residual data based on the sheath current information and simulation results, the method further includes: dynamically correcting the simulation results based on the service time of the power distribution cable.

[0018] The technical solution adopted by this invention to solve its technical problem is: to provide a device for analyzing and diagnosing insulation defects in power distribution cables, comprising:

[0019] The building module is used to construct a three-dimensional finite element model of a power distribution cable that includes a copper shielding layer, an insulation layer, and a sheath structure.

[0020] The simulation module is used to perform electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the power distribution cable, obtain simulation results, simulate the current leakage characteristics caused by local damage to the sheath, and generate a fault feature library.

[0021] The acquisition module is used to collect real-time sheath current information of the power distribution cable body and joints;

[0022] The calculation and judgment module is used to calculate multi-parameter residual data based on the sheath current information and simulation results, and input the multi-parameter residual data into the fault judgment model;

[0023] The analysis module is used to perform fault analysis based on the fault feature library and generate early warning strategies when the fault judgment model determines that a fault exists.

[0024] The technical solution adopted by the present invention to solve its technical problem is: to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-mentioned method for analyzing and diagnosing insulation defects in power distribution cables.

[0025] The technical solution adopted by the present invention to solve its technical problem is: to provide a computer-readable storage medium on which a computer program is stored, wherein the computer program, when executed by a processor, implements the steps of the above-mentioned method for analyzing and diagnosing insulation defects in power distribution cables.

[0026] Beneficial effects

[0027] Due to the adoption of the above technical solutions, this invention has the following advantages and positive effects compared with the prior art: This invention realizes the analysis and diagnosis of sheath current faults in distribution network cables through COMSOL multiphysics coupling simulation technology, significantly improving the detection sensitivity and positioning accuracy of hidden defects such as cable grounding faults. Compared with the traditional single-phase model, it can significantly improve the fault identification accuracy, providing a solution for the operation and maintenance of distribution network cables and effectively reducing the failure to report faults. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method for analyzing and diagnosing insulation defects in power distribution cables according to the first embodiment of the present invention;

[0029] Figure 2 This is a diagram of a power distribution cable model constructed in the first embodiment of the present invention. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0031] The first embodiment of the present invention relates to a method for analyzing and diagnosing insulation defects in power distribution cables, such as... Figure 1 As shown, it includes the following steps:

[0032] Step 1: Construct a three-dimensional finite element model of the power distribution cable, which includes a copper shielding layer, an insulation layer, and a sheath structure.

[0033] In this step, a three-dimensional finite element model of the power distribution cable is established using COMSOL Multiphysics software (see...). Figure 2 When constructing, the spatial structure and electromagnetic coupling characteristics of the three-phase conductors, metal shielding layer and insulating materials are considered.

[0034] Step 2: Perform electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the power distribution cable to obtain simulation results, and simulate the current leakage characteristics caused by local damage to the sheath to generate a fault feature library.

[0035] In this step, the distribution of sheath current at the cable body and joints is simulated by defining frequency-varying material parameters (such as the relationship between conductivity and frequency and the relationship between dielectric constant and frequency) and nonlinear boundary conditions (such as cross-interconnection grounding impedance), thus obtaining the simulation results of sheath current at the cable body and joints. The fault feature library generated in this step includes several typical fault features, such as increased current amplitude and phase shift.

[0036] Compared with the traditional single-phase model, the three-dimensional finite element model constructed in this embodiment can more realistically reflect the influence of three-phase unbalanced current on sheath current, providing a high-precision data foundation for fault analysis and diagnosis.

[0037] Step 3: Collect real-time sheath current information of the power distribution cable body and joints.

[0038] In this step, the sheath current information of the power distribution cable can be collected in real time using a high-frequency sensor array. The high-frequency sensor array can be a high-frequency Rogowski coil sensor array deployed at key locations such as cable joints and grounding boxes, and the bandwidth of the collected sheath current information is 0.1Hz-1MHz.

[0039] Step 4: Calculate multi-parameter residual data based on the sheath current information and simulation results, and input the multi-parameter residual data into the fault judgment model.

[0040] In this step, multi-parameter residual data is calculated based on the sheath current information and simulation results. This includes the calculation of sheath current residual data for cable joints and sheath current residual data for the cable body. Taking the calculation of sheath current residual data for cable joints as an example, the specific steps are as follows: subtract the amplitude of the sheath current information of the collected cable joint from the current amplitude information of the cable joint in the simulation results to obtain the current amplitude residual data of the cable joint; subtract the phase of the sheath current information of the collected cable joint from the current phase information of the cable joint in the simulation results to obtain the current phase residual data of the cable joint.

[0041] The above calculations yield multi-parameter residual data, which is then input into a fault diagnosis model to determine the presence of a fault. In this embodiment, the fault diagnosis model is a lightweight ROM model. It divides all multi-parameter residual data by the simulation results corresponding to each parameter to obtain ratios. When any ratio exceeds a preset value, a fault is considered to exist. Specifically, the current amplitude residual data of the cable joint is divided by the current amplitude information of the cable joint in the simulation results to obtain a current amplitude ratio for the cable joint; the current phase residual data of the cable joint is divided by the current phase information of the cable joint in the simulation results to obtain a current phase ratio for the cable joint; and each residual data of the cable body is divided by the simulated value of the cable body in the simulation results to obtain a ratio for each cable body. If any of the above ratios exceeds 15%, the distribution cable is considered to have a fault.

[0042] It is worth mentioning that before calculating the residual data, this embodiment can also dynamically correct the simulation results based on the service time of the power distribution cable. Dynamic correction can ensure that the accuracy of analysis and diagnosis is maintained even when the cable ages or the environment changes.

[0043] Step 5: When the fault judgment model determines that a fault exists, fault analysis is completed based on the fault feature library, and an early warning strategy is generated.

[0044] In this step, when performing fault analysis based on the fault feature library, the parameter corresponding to the ratio exceeding a preset value is determined. The fault feature library is then searched based on the characteristics of this parameter to determine the location and type of the fault. Finally, the fault is classified according to the magnitude of the ratio. For example, assuming the parameter corresponding to the ratio exceeding the preset value is the current amplitude of a certain cable joint, the fault feature library generated in step 2 is searched using the current amplitude of a certain cable joint as a keyword. The search retrieves the cable joint identifier and faults with increased current amplitude, thus determining the location and type of the fault. Then, it is determined whether the ratio is between 15% and 20%. If it is, the fault is classified as level three; if not, it is further determined whether the ratio is between 20% and 25%. If it is, the fault is classified as level two; if not, the fault is classified as level one.

[0045] Therefore, this implementation method establishes a multi-parameter collaborative analysis system for sheath current, integrates amplitude deviation and phase shift processing, sets up a three-level early warning mechanism, achieves accurate fault classification, and can precisely locate defects based on the matching results of the fault feature database, thus significantly shortening maintenance time. This method can effectively reduce unnecessary power outages, lower annual maintenance costs, and significantly improve power supply reliability.

[0046] The second embodiment of the present invention relates to a device for analyzing and diagnosing insulation defects in power distribution cables, comprising:

[0047] The building module is used to construct a three-dimensional finite element model of a power distribution cable that includes a copper shielding layer, an insulation layer, and a sheath structure.

[0048] The simulation module is used to perform electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the power distribution cable, obtain simulation results, simulate the current leakage characteristics caused by local damage to the sheath, and generate a fault feature library.

[0049] The acquisition module is used to collect real-time sheath current information of the power distribution cable body and joints;

[0050] The calculation and judgment module is used to calculate multi-parameter residual data based on the sheath current information and simulation results, and input the multi-parameter residual data into the fault judgment model;

[0051] The analysis module is used to perform fault analysis based on the fault feature library and generate early warning strategies when the fault judgment model determines that a fault exists.

[0052] When constructing a three-dimensional finite element model of a power distribution cable that includes a copper shielding layer, an insulation layer, and a sheath structure, the construction module considers the spatial structure and electromagnetic coupling characteristics of the three-phase conductors, the metal shielding layer, and the insulation material.

[0053] When the simulation module performs electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the power distribution cable, it simulates the distribution law of sheath current at the cable body and joint by defining frequency-varying material parameters and nonlinear boundary conditions.

[0054] When the acquisition module collects the sheath current information of the power distribution cable body and joints in real time, it uses a high-frequency sensor array to collect sheath current signals with a bandwidth of 0.1Hz-1MHz.

[0055] When judging the multi-parameter residual data, the fault judgment model calculates the ratio of the multi-parameter residual data to the simulation results of the corresponding parameters. If any ratio exceeds a preset value, a fault is judged to exist.

[0056] When the analysis module performs fault analysis based on the fault feature library, it determines the parameter corresponding to the ratio exceeding the preset value, searches the fault feature library according to the characteristics of the parameter, determines the location and type of the fault, and then classifies the fault according to the size of the ratio.

[0057] The power distribution cable insulation defect analysis and diagnosis device also includes a dynamic correction module, which is set before the calculation and judgment module and is used to dynamically correct the simulation results according to the service time of the power distribution cable.

[0058] The third embodiment of the present invention relates to an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the distribution cable insulation defect analysis and diagnosis method of the first embodiment.

[0059] The fourth embodiment of the present invention relates to a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method for analyzing and diagnosing insulation defects in power distribution cables according to the first embodiment.

[0060] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0061] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0062] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction methods implemented in a process. Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0063] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0064] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of diagnosing an insulation defect of a power distribution cable, characterized by, The method comprises the following steps: constructing a three-dimensional finite element model of the power distribution cable comprising a copper shielding layer, an insulation layer, and a sheath structure; performing electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the power distribution cable to obtain simulation results, and simulating current leakage characteristics caused by local damage of the sheath to generate a fault feature library; real-time acquisition of sheath current information at the power distribution cable body and joint; calculation of multi-parameter residual data according to the sheath current information and the simulation results, and input of the multi-parameter residual data into a fault judgment model; when the judgment result of the fault judgment model is that there is a fault, completing fault analysis based on the fault feature library and generating an early warning strategy.

2. The power distribution cable insulation defect analysis and diagnostic method of claim 1, wherein, When constructing the three-dimensional finite element model of the power distribution cable comprising the copper shielding layer, the insulation layer, and the sheath structure, the spatial structure and electromagnetic coupling characteristics of the three-phase conductor, the metal shielding layer, and the insulation material are considered.

3. The power distribution cable insulation defect analysis and diagnostic method of claim 1, wherein, When performing electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the power distribution cable, the distribution law of the sheath current at the cable body and the joint is simulated by defining frequency-dependent material parameters and nonlinear boundary conditions.

4. The power distribution cable insulation defect analysis and diagnostic method of claim 1, wherein, When real-time acquisition of the sheath current information at the power distribution cable body and joint is performed, a high-frequency sensor array is used to acquire the sheath current signal with a bandwidth of 0.1 Hz-1 MHz.

5. The power distribution cable insulation defect analysis and diagnostic method of claim 1, wherein, When the fault judgment model judges the multi-parameter residual data, the ratio of the multi-parameter residual data to the simulation result of the corresponding parameter is calculated, and when one of the ratios exceeds a preset value, it is judged that there is a fault.

6. The power distribution cable insulation defect analysis and diagnostic method of claim 5, wherein, Completing fault analysis based on the fault feature library specifically includes: determining the parameter corresponding to the ratio exceeding the preset value, searching the fault feature library according to the characteristics of the parameter, determining the location and type of the fault, and classifying the fault according to the size of the ratio.

7. The power distribution cable insulation defect analysis and diagnostic method of claim 1, wherein, Before calculating the multi-parameter residual data according to the sheath current information and the simulation results, the simulation results are dynamically corrected according to the use time of the power distribution cable.

8. A power distribution cable insulation defect analysis and diagnosis apparatus characterized by comprising: It comprises: a construction module for constructing a three-dimensional finite element model of the power distribution cable comprising a copper shielding layer, an insulation layer, and a sheath structure; a simulation module for performing electro-magnetic-thermal coupling simulation on the three-dimensional finite element model of the power distribution cable to obtain simulation results, and simulating current leakage characteristics caused by local damage of the sheath to generate a fault feature library; an acquisition module for real-time acquisition of sheath current information at the power distribution cable body and joint; a calculation and judgment module for calculating multi-parameter residual data according to the sheath current information and the simulation results, and inputting the multi-parameter residual data into a fault judgment model; an analysis module for completing fault analysis based on the fault feature library and generating an early warning strategy when the judgment result of the fault judgment model is that there is a fault.

9. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the computer program to realize the steps of the power distribution cable insulation defect analysis and diagnosis method according to any one of claims 1-7.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the power distribution cable insulation defect analysis and diagnosis method according to any one of claims 1-7.

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