Electrified maintenance method and system for power cable cross interconnection grounding system

Abstract

The invention relates to the field of power systems, in particular to a power cable cross interconnection grounding system live-line maintenance method and system. The method comprises the following steps: firstly, synchronously acquiring cable line load current, three-phase grounding ring current and grounding resistance at the head end and the tail end of a metal sheath of a crossed interconnection unit with ring current abnormity, and generating a real-time data set with a timestamp; extracting cable structure parameters based on a preset cable topology database, and dynamically associating the cable structure parameters with the real-time data set; constructing a multi-conductor transmission line equation model, calculating a theoretical circulation distribution value of each section of sheath, and generating a theoretical circulation map; carrying out matching analysis on the theoretical circulation map and actually measured circulation data, and determining defect types and positions; and finally, according to a defect positioning result, the maintenance operation is executed in an electrified state through the insulating mechanical arm, and the stability of the grounding impedance of the system is maintained through the bypass grounding device. The problems that in the prior art, the live detection function is incomplete, and defects cannot be rapidly and accurately positioned are solved.

Description

Technical Field

[0001] The present invention relates to the field of power systems, and in particular to a live maintenance method and system for a power cable cross-interconnected grounding system. Background Art

[0002] The cross-connected grounding system of power cables is a key part of the safe operation of high-voltage cable lines. Its main function is to reduce the induced voltage and circulating current of the cable metal sheath and ensure the stable operation of the power system. However, the existing technology has many shortcomings in terms of maintenance. For example, the Chinese patent number CN113640574A discloses an online monitoring device and monitoring method for the grounding loop current of the tunnel cable sheath. Although it can realize online monitoring of the grounding loop current of the cable sheath, in actual application, the accuracy of its test results is still insufficient, especially in complex operating environments, and it is easy to make misjudgments and missed judgments.

[0003] Furthermore, traditional methods for inspecting and repairing cable cross-connect grounding systems often require power outages. This approach is not only time-consuming and labor-intensive, but also results in significant waste of manpower and material resources, prolonged power outages, and may even lead to misdiagnosis of the cause of defects. While some live-line inspection methods and devices exist in the prior art, most can only detect the presence of defects but cannot accurately determine their specific cause and location, resulting in low inspection efficiency.

[0004] In high-voltage cable lines, due to factors such as installation spacing and length, the induced voltages in the metal sheath's cross-connected grounding system cannot offset each other, causing circulating currents. Excessive circulating currents can easily overheat the cable lines, accelerating insulation aging and causing failures. Traditional detection methods rely solely on theoretical calculations or post-energized testing, which can result in large errors and high costs for decommissioning and rectification.

[0005] In response to the deficiencies in the prior art, the present application proposes a live maintenance method and system for a power cable cross-connected grounding system. Summary of the Invention

[0006] The purpose of the present invention is to provide a live inspection method and system for a power cable cross-interconnected grounding system, so as to solve the problem in the prior art that the live inspection function is imperfect and the defects cannot be located quickly and accurately.

[0007] To achieve the above objectives, the following technical solutions are adopted.

[0008] A live maintenance method for a power cable cross-connection grounding system comprises the following steps:

[0009] S1. Synchronously collect the cable line load current, three-phase grounding circulation current, and metal sheath head-end grounding resistance of the cross-connected unit with abnormal circulation current, and generate a real-time data set with a time stamp;

[0010] S2, extracting cable structure parameters based on a preset cable topology database and dynamically associating them with the real-time data set of step S1;

[0011] S3. Based on the real-time data set of step S1 and the associated parameters of step S2, a multi-conductor transmission line equation model is constructed, the theoretical circulating current distribution value of each sheath section is calculated, and a theoretical circulating current map is generated;

[0012] S4. Match and analyze the theoretical circulating current map with the measured circulating current data, and determine the defect type and location based on single-phase polarity reversal, three-phase deviation uniformity, and ground resistance anomaly;

[0013] S5. Based on the defect location results, maintenance operations are performed under power conditions using an insulated robotic arm, while maintaining the stability of the system grounding impedance through a bypass grounding device.

[0014] Optionally, the specific steps of synchronous data acquisition in step S1 include:

[0015] A distributed optical fiber sensor array is laid along the cross-connection section to collect the three-phase ground loop current data of the cable line in real time;

[0016] A high-precision clock synchronization module is used to align the acquisition timestamps of the load current and the three-phase ground loop current to ensure the timing consistency of different segments of data. The clock synchronization module uses GPS / Beidou dual-mode signals to achieve cross-regional time base unification.

[0017] The synchronously collected load current, ground loop current, and ground resistance data are transmitted to the central processing unit in real time via a wireless transmission network, generating a real-time data set with a unified time stamp.

[0018] The real-time data set is used as the input of the circulating current calculation model in step S3 to establish the spatiotemporal correlation between the sheath circulating current and the load current.

[0019] Optionally, the specific steps of obtaining the cable structure parameters and dynamically associating them in step S2 include:

[0020] Retrieving the metal sheath inner diameter, outer diameter, and phase spacing parameters of the target cross-connection segment based on a preset cable topology database, wherein the database stores standard structural parameters corresponding to different cable models;

[0021] The length of each cable segment is measured in real time by a laser distance measuring device, and the measured length data is integrated with the standard parameters retrieved from the preset database;

[0022] A dynamic mapping relationship between the structural parameters and the load current, ground loop current, and ground resistance data collected synchronously in step S1 is established, wherein the mapping relationship includes:

[0023] Bind the inner diameter and outer diameter parameters of the sheath with the ground loop current data in spatial position to form a sheath electromagnetic parameter association set;

[0024] The length and phase spacing parameters of each cable segment are time-series aligned with the load current data to generate a cable topology current distribution model;

[0025] The dynamic mapping relationship is used to synchronously load the sheath structural parameters and the real-time electrical data when constructing the multi-conductor transmission line equation model in step S3, so as to correct the electromagnetic coupling deviation in the theoretical circulating current calculation.

[0026] Optionally, it is characterized in that the specific steps of constructing the multi-conductor transmission line equation model and calculating the theoretical circulating current distribution value in step S3 include:

[0027] Based on the load current and grounding resistance values ​​collected synchronously in step S1 and the cable structure parameters obtained in step S2, a multi-conductor transmission line equation model is established, where:

[0028] The multi-conductor transmission line equation model takes the impedance distribution parameters of the cable metal sheath as input, and combines the cross-connected segment topology to make each sheath segment equivalent to a multi-conductor transmission line network;

[0029] The measured ground resistance value collected in step S1 is introduced into the model as a boundary condition, and the electromagnetic coupling equation of each sheath section is solved by the finite element iteration method to calculate the distribution relationship of the current between the sheaths;

[0030] Correcting the electromagnetic coupling coefficient between the sheaths based on the phase spacing parameter in step S2, and dynamically adjusting the potential difference between the conductors of the transmission line equation according to the real-time distribution data of the load current;

[0031] The theoretical circulation distribution value of each section of the sheath is output through iterative calculation to generate a theoretical circulation map corresponding to the spatial position of the cross-connected section; the theoretical circulation map is used to perform spatial matching analysis with the measured circulation data in step S4 to locate the defect position.

[0032] Optionally, the specific steps of step S4 include:

[0033] S4.1. Align the theoretical circulation map generated in step S3 with the measured circulation data collected in step S1 in time and space to generate a difference feature vector containing amplitude difference and phase difference;

[0034] S4.2. Based on the difference feature vector, extract the polarity reversal characteristics of the single-phase circulating current direction and the theoretical spectrum, the uniformity characteristics of the three-phase circulating current amplitude deviation, and the deviation characteristics of the ground resistance value from the theoretical boundary;

[0035] S4.3. Determine whether the sheath is damaged or the cross-connection box wiring is abnormal based on the polarity reversal feature, determine the ground resistance degradation area based on the uniformity feature, and locate the impedance mutation point based on the deviation feature;

[0036] S4.4. Decompose the circulating current signal in the section where the impedance mutation point is located in the time-frequency domain, extract the amplitude mutation characteristics of the high-frequency component through wavelet transform, and combine the spatial coordinate data in the cable topology database to output the GIS geographic coordinates of the defect location;

[0037] S4.5. Generate a maintenance instruction based on the defect type and GIS geographic coordinates, wherein the maintenance instruction includes the defect location coordinates, the maintenance operation type, and the impedance adjustment parameters of the bypass grounding device.

[0038] Optionally, the specific steps of step S5 include:

[0039] S5.1. Receive the maintenance instruction output in step S4, and analyze the defect location coordinates, maintenance operation type, and impedance adjustment parameters in the maintenance instruction;

[0040] S5.2. According to the maintenance operation type, call a corresponding maintenance tool from the tool library of the insulating manipulator, and generate an impedance adjustment instruction for the bypass grounding device based on the impedance adjustment parameter;

[0041] S5.3. Generate a moving path planning instruction for the insulation manipulator based on the defect location coordinates and the spatial mapping relationship between the laser positioning module and the cable topology database;

[0042] S5.4. After the insulating manipulator moves along the movement path to the defect location, the maintenance tool is activated to perform live operation, and the access impedance of the bypass grounding device is dynamically adjusted according to the impedance adjustment instruction;

[0043] S5.5. During the maintenance operation, the impedance changes of the grounding system are monitored in real time. When the impedance fluctuation exceeds the preset threshold, the dynamic compensation mechanism of the bypass grounding device is triggered until the maintenance operation is completed and the system impedance returns to stability.

[0044] Optionally, the specific steps of extracting the high-frequency component amplitude mutation feature by wavelet transform in step S4.4 include:

[0045] S4.4.1. Extract the time domain waveform sequence and divide the signal window based on the circulating current signal in the section where the impedance mutation point is located;

[0046] S4.4.2. Perform multi-scale wavelet decomposition on the circulation data of each signal window to separate the high-frequency components within a preset frequency band;

[0047] S4.4.3. Calculate the difference in the high-frequency component amplitudes of adjacent windows. If the difference exceeds the dynamic threshold range, mark it as an amplitude mutation feature point.

[0048] S4.4.4. Determine the physical segment of the defect in the cable cross-connection segment based on the time domain distribution density of the amplitude mutation characteristic points and the spatial segmentation information in the cable topology database;

[0049] S4.4.5. Spatial mapping of the physical segment with the GIS geographic coordinates is performed to output the precise geographic coordinates of the defect location.

[0050] Optionally, the step S5 further includes a closed-loop verification step S6:

[0051] S6.1. After the live maintenance operation is completed in step S5, steps S1 to S3 are re-executed to generate a theoretical circulation diagram after maintenance;

[0052] S6.2. Match and analyze the theoretical circulation map after repair with the measured circulation data collected again in step S1. If the amplitude difference and phase difference in the difference feature vector are both less than the preset threshold, the defect repair is determined to be successful;

[0053] S6.3. If it is determined that the defect is not repaired successfully, the defect location logic of step S4 is triggered based on the difference feature vector of step S6.2, a secondary repair instruction is generated and the process returns to step S5 for execution.

[0054] A live maintenance system for a power cable cross-connection grounding system, comprising:

[0055] The data acquisition module is used to synchronously collect the cable line load current, three-phase grounding circulation current, and metal sheath head-end grounding resistance of the cross-connected units with abnormal circulation current, and generate a real-time data set with a time stamp;

[0056] A parameter association module, connected to the data acquisition module, for extracting cable structure parameters based on a preset cable topology database and dynamically associating them with the real-time data set;

[0057] a model construction module, connected to the parameter association module, for constructing a multi-conductor transmission line equation model based on the real-time data set and the associated parameters, calculating the theoretical circulating current distribution value of each section of the sheath, and generating a theoretical circulating current map;

[0058] a defect analysis module, connected to the model building module, for matching and analyzing the theoretical circulating current map with the measured circulating current data, and determining the defect type and location based on single-phase polarity reversal, three-phase deviation uniformity, and ground resistance anomaly;

[0059] The maintenance execution module is connected to the defect analysis module and includes an insulating mechanical arm and a bypass grounding device. It is used to perform maintenance operations in a live state according to the defect location results, and maintain the stability of the system grounding impedance by dynamically adjusting the access impedance of the bypass grounding device.

[0060] Optionally, the maintenance execution module includes:

[0061] An instruction parsing unit, configured to receive the repair instruction output by the defect analysis module and parse the defect location coordinates, repair operation type, and impedance adjustment parameters;

[0062] a tool calling unit connected to the instruction parsing unit, configured to call a corresponding maintenance tool from a tool library of the insulating manipulator according to the maintenance operation type, and generate an impedance adjustment instruction for the bypass grounding device;

[0063] A path planning unit, connected to the instruction parsing unit, is used to generate a moving path planning instruction for the insulation manipulator based on the spatial mapping relationship between the defect location coordinates and the cable topology database;

[0064] An operation control unit, connected to the path planning unit and the tool calling unit, is used to control the insulating manipulator to move along the planned path to the defect location, start the maintenance tool to perform the operation, and synchronously trigger the impedance dynamic adjustment of the bypass grounding device;

[0065] The dynamic compensation unit is used to monitor the impedance changes of the grounding system in real time. When the impedance fluctuation exceeds the preset threshold, the compensation mechanism of the bypass grounding device is triggered to maintain the system impedance stability until the maintenance is completed.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] The present application proposes a method for live maintenance of a power cable cross-interconnected grounding system, which effectively solves many problems existing in the prior art and significantly improves the efficiency and reliability of power cable maintenance. First, in response to the problems in the prior art of imperfect live detection functions, inability to quickly and accurately locate defects and perform live maintenance, the present invention synchronously collects multiple electrical parameters of the cable line and uses a multi-conductor transmission line equation model to calculate the theoretical circulating current distribution, thereby achieving accurate matching analysis with the measured data, thereby being able to quickly and accurately determine the type and location of the defect. Not only does it improve maintenance efficiency and reduce maintenance time, it also effectively avoids the long-term power outages and resource waste caused by traditional power outage maintenance, significantly improving the continuity and reliability of power supply. In addition, by performing maintenance operations in a live state and maintaining the stability of the system grounding impedance with the help of a bypass grounding device, the present invention further ensures the safety of the maintenance process and reduces the risk of system failures due to unstable grounding impedance.

[0068] Furthermore, the present invention ensures the accuracy and synchronization of data acquisition through a high-precision distributed fiber optic sensor array and clock synchronization module, providing a more reliable data foundation for subsequent analysis and judgment. Simultaneously, by dynamically correlating cable structural parameters and optimizing the construction of a multi-conductor transmission line equation model, the accuracy of theoretical circulating current calculations is further improved, thereby more precisely locating defect locations. Furthermore, the introduction of a feedback loop and edge computing nodes enables real-time monitoring and rapid response to circulating current data, improving the system's intelligence and operational stability. For example, during maintenance, by monitoring the impedance changes of the grounding system in real time and detecting impedance fluctuations exceeding a preset threshold, the dynamic compensation mechanism of the bypass grounding device is triggered, ensuring the stability of the system impedance until the maintenance is completed. This intelligent monitoring and compensation mechanism not only improves the safety and reliability of maintenance operations but also effectively reduces the impact of maintenance operations on grid operations. Furthermore, a closed-loop verification step further ensures the accuracy and reliability of maintenance results, avoids potential risks caused by incomplete maintenance, improves maintenance efficiency, and reduces unnecessary repetitive maintenance work. In summary, the present invention not only effectively solves the problems existing in the prior art, but also provides an efficient, safe and reliable new method and system for the maintenance of power cable cross-connection grounding systems, which has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 The present invention is a flowchart of the steps of an embodiment of a method for live maintenance of a power cable cross-interconnected grounding system.

[0070] Figure 2 The present invention is a module diagram of an embodiment of a live maintenance system for a power cable cross-interconnected grounding system according to the present invention. DETAILED DESCRIPTION

[0071] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0072] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise indicated, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0073] Example 1

[0074] like Figure 1 As shown, a live maintenance method for a power cable cross-connection grounding system includes the following steps:

[0075] Synchronously collect the load current, three-phase grounding circulation current and grounding resistance of the cable line at the beginning and end of the cross-connected units with abnormal circulation, and generate a real-time data set with a time stamp. Specifically, use high-precision current sensors and grounding resistance testers to accurately measure the load current, three-phase grounding circulation current and grounding resistance of the cable line at the beginning and end of the metal sheath, and use the synchronous timing module to ensure that all data are collected at the same time to ensure the accuracy and relevance of the data. The measured data will be accompanied by a time stamp to form a real-time data set, which provides a basis for subsequent analysis. The synchronous timing module uses high-precision clock synchronization technology to ensure that the data at different measurement points have a high degree of time consistency, which is crucial for accurate analysis of circulation anomalies;

[0076] Cable structural parameters are extracted based on a pre-set cable topology database and dynamically associated with the above-mentioned real-time data set. The cable topology database stores detailed structural parameters of different cable models, including the inner and outer diameters of the metal sheath, the length of the cable segment, and the phase spacing. In actual applications, the corresponding structural parameters are retrieved from the database based on the model of the cable to be tested. These parameters are combined with the real-time collected electrical data to provide the necessary basic information for subsequent circulation calculations and defect location. Through the dynamic association mechanism, parameters can be updated and adjusted in real time to adapt to different testing environments and conditions, ensuring the accuracy and reliability of the test results.

[0077] Based on the above real-time data sets and associated parameters, a multi-conductor transmission line equation model is constructed to calculate the theoretical circulating current distribution values ​​of each sheath section and generate a theoretical circulating current map. The multi-conductor transmission line equation model is established using the cable's structural parameters and real-time electrical data. This model can simulate the electromagnetic field distribution in the cable system and accurately calculate the theoretical circulating current distribution of each sheath section under different conditions. By solving the equation model, the theoretical circulating current distribution values ​​are obtained and visualized as a theoretical circulating current map, which intuitively displays the distribution of the circulating current in the cable system and provides a theoretical basis for subsequent matching analysis and defect location.

[0078] The theoretical circulating current map is matched and analyzed with the measured circulating current data. The defect type and location are determined based on single-phase polarity reversal, three-phase deviation uniformity, and ground resistance anomaly. The real-time circulating current data is compared and analyzed with the theoretical circulating current map. The location and type of circulating current anomalies are identified through specific algorithms and criteria, such as single-phase polarity reversal, three-phase deviation uniformity, and ground resistance anomaly. These criteria are derived from the electrical characteristics of the cable system and common defect patterns. They can effectively distinguish between normal conditions and various defective conditions, accurately determining the specific location and type of defects and providing clear guidance for subsequent maintenance work.

[0079] Based on the defect location results, maintenance operations are performed live using an insulated robotic arm, while the bypass grounding device maintains the stability of the system's ground impedance. After determining the defect location and type, live maintenance operations are performed using the insulated robotic arm. The insulated robotic arm, with its excellent insulation performance and precise operation, enables safe maintenance of the cable system without power outages, effectively minimizing outage duration and impact on users. Furthermore, the bypass grounding device maintains the stability of the system's ground impedance during the maintenance process, ensuring safe operation of the entire system and preventing failures and risks caused by ground impedance fluctuations.

[0080] As a specific example, when implementing the live maintenance method of the power cable cross-interconnected grounding system, synchronous data acquisition not only involves the application of a variety of advanced equipment and technologies, but also requires following specific operating procedures to ensure that the collected data is highly accurate, timely and consistent.

[0081] First, distributed fiber optic sensor arrays need to be laid along the cable lines in the cross-connection sections. These sensor arrays use optical fibers as sensitive elements and detect physical quantities such as temperature, strain, and vibration by measuring changes in backscattered light. For example, a distributed fiber optic white light interferometer sensor array based on a tunable Fabry-Perot resonant cavity can be used. This sensor array structure includes duplex optoelectronic devices, a tunable Fabry-Perot resonant cavity, single-mode connecting optical fibers, and sensors. Its operating principle is that a light beam emitted by a broadband light source is reflected multiple times within the resonant cavity. The signal light is then reflected and returned by the fiber optic sensor and ultimately detected by a photodetector, thereby enabling real-time acquisition of three-phase ground loop current data on the cable line.

[0082] During data collection, a high-precision clock synchronization module is used to align the collection timestamps of the load current and three-phase ground loop current to ensure timing consistency across different segments. This clock synchronization module uses GPS / Beidou dual-mode signals to unify the time base across regions, ensuring the accuracy and reliability of the collected data. This allows the collected load current, ground loop current, and ground resistance data to be recorded with a unified timestamp, providing a foundation for subsequent data processing and analysis.

[0083] The collected data is transmitted in real time via a wireless transmission network to the central processing unit. There, it undergoes preliminary processing and integration into a real-time data set with a unified timestamp. This data set not only contains the measured values ​​of various electrical parameters but also records the time and location of data acquisition, providing the foundation for subsequent circulating current calculations and defect location.

[0084] To improve data acquisition accuracy and reliability, a distributed fiber optic sensor array is used for real-time monitoring. This sensor array uses a pulsed light source to transmit optical signals through optical fibers, generating phase shifts when encountering disturbances, enabling real-time monitoring of cable lines. This method accurately captures parameters such as load current, three-phase ground loop current, and ground resistance, generating a real-time, time-stamped data set.

[0085] Finally, the collected data will be used as input for the subsequent circulating current calculation model to establish the temporal and spatial correlation between the sheath circulating current and the load current. This step is the key to the entire live maintenance method and provides accurate data support for subsequent defect location and maintenance.

[0086] As a specific example, the specific operations of obtaining the cable structure parameters and dynamically associating them in step S2 are as follows:

[0087] To ensure the accuracy of subsequent circulating current calculations, the metal sheath inner and outer diameters and phase spacing parameters of the target cross-connection segment must first be retrieved from a pre-configured cable topology database. This database contains a comprehensive record of the standard structural parameters of common commercially available cable models, covering cable types of varying voltage levels and application scenarios, providing basic data support for maintenance.

[0088] To ensure real-time and accurate data, a laser ranging device is used to measure the length of each cable segment in real time. Triangulation is used to accurately calculate cable length by measuring the angle of the laser beam reflected from the target object and the time of the initial pulse. After processing, the measured data is integrated with standard parameters in a database to form a complete set of cable structural parameters, providing an accurate physical model for circulation calculations.

[0089] A dynamic mapping relationship is established between structural parameters and the data collected synchronously in step S1. First, the sheath inner and outer diameter parameters are spatially bound to the ground loop current data to form a sheath electromagnetic parameter association set, which intuitively reflects the correspondence between the electromagnetic characteristics of the cable sheath and its spatial distribution. Second, the cable length and phase spacing parameters are aligned with the load current data in a time series to generate a cable topology current distribution model. This model demonstrates the dynamic characteristics of the cable line current over time and provides detailed data support in the spatial and temporal dimensions for the circulating current calculation model.

[0090] Dynamic mapping relationships play a key role in constructing the multi-conductor transmission line equation model in step S3. By loading sheath structural parameters and real-time electrical data, electromagnetic coupling deviations in the theoretical circulating current calculations can be corrected. For example, when a cable has localized damage or a loose connection, changes in the sheath structural parameters can affect the electromagnetic coupling effect. Using dynamic mapping relationships, the model can accurately identify and correct these deviations, improving the accuracy of the theoretical circulating current calculations and laying a solid foundation for subsequent defect location and analysis.

[0091] As a specific example, the implementation of step S3 is as follows:

[0092] To construct the multi-conductor transmission line equation model and calculate the theoretical circulating current distribution, the model is first established based on the load current and grounding resistance values ​​collected simultaneously in step S1 and the cable structural parameters obtained in step S2. During this process, the impedance distribution parameters of the cable's metal sheath are used as input. Combined with the topological structure of the cross-connected segments, each sheath segment is equivalent to a multi-conductor transmission line network. The model establishment must consider multiple factors, including the cable's geometric dimensions, material properties, and electromagnetic field distribution, to ensure that the model accurately reflects the actual operating conditions of the cable.

[0093] Next, the measured value of the grounding resistance collected in step S1 is introduced into the model as a boundary condition. The electromagnetic coupling equations of each sheath section are solved by the finite element iteration method, and then the current distribution relationship between the sheaths is calculated. The finite element iteration method is a numerical calculation method that discretizes the continuous electromagnetic field problem, decomposes it into multiple finite-sized units, and then gradually approaches the true solution through iterative calculation. During the calculation process, it is necessary to set appropriate grid division and boundary conditions based on factors such as the material, shape and size of the cable to improve the accuracy and efficiency of the calculation.

[0094] At the same time, the electromagnetic coupling coefficient between the sheaths is modified based on the phase spacing parameter obtained in step S2. This is because changes in phase spacing affect the electromagnetic induction intensity between cables, which in turn affects the distribution of circulating currents. By modifying the electromagnetic coupling coefficient, the electromagnetic field distribution in the cable system can be more accurately simulated, improving the accuracy of the theoretical circulating current calculation.

[0095] The potential difference between conductors in the transmission line equation is then dynamically adjusted based on real-time load current distribution data. This real-time load current data reflects the load conditions of the cable during actual operation. Adjusting the potential difference based on this data allows the model to better adapt to the cable's varying operating conditions, further improving the reliability of the calculation results.

[0096] Finally, an iterative calculation outputs the theoretical circulating current distribution values ​​for each sheath segment and generates a theoretical circulating current map corresponding to the spatial location of the cross-connected segments. Iterative calculation is a method that gradually approximates the true value. During each iteration, the model parameters and boundary conditions are continuously updated until the calculated results meet the set convergence criteria. The theoretical circulating current map intuitively displays the theoretical circulating current distribution of each cable segment, providing an important basis for subsequent analysis and decision-making.

[0097] This theoretical circulating current map is used in step S4 for spatial matching analysis with the measured circulating current data to accurately locate the defect. By comparing the differences between the theoretical and measured circulating currents, anomalies in the cable system can be quickly and accurately identified, providing key guidance for live maintenance and ensuring the safe and stable operation of the power system.

[0098] As a preferred example, in step S5, during the defect analysis phase, the theoretical circulation map and the measured circulation data collected in real time are first aligned in time and space, specifically including time synchronization and spatial position mapping. The timestamps of the theoretical map and the measured data are calibrated based on the Beidou timing module to ensure strict synchronization of the two in the time dimension; at the same time, according to the spatial coordinates of the cross-connected segments stored in the cable topology database, the current distribution values ​​of each section of the sheath in the theoretical circulation map are spatially bound with the measured data according to the cable laying path to form a time-space aligned difference data set. The difference data set generates a multi-dimensional difference feature vector by calculating the absolute value of the amplitude difference and the phase difference angle between the theoretical value and the measured value, where the amplitude difference reflects the degree of deviation of the current amplitude and the phase difference represents the consistency of the current direction.

[0099] Based on the difference feature vector, three types of abnormal features are extracted respectively:

[0100] Polarity reversal feature: Analyze the direction of single-phase circulating current through vector projection. If the measured circulating current direction is opposite to the current direction of the corresponding phase in the theoretical spectrum (i.e., the phase difference exceeds 150°), it is determined that the sheath of the phase is damaged or the cross-connection box wiring is incorrect;

[0101] Uniformity feature: Calculate the variance of the three-phase circulating current amplitude difference. If the three-phase deviation variance exceeds the preset threshold and the deviation distribution is uniform, it is determined that the overall ground resistance has deteriorated.

[0102] Impedance deviation characteristics: Compare the measured ground resistance value with the theoretical boundary range. If a certain section of ground resistance continuously deviates from the theoretical boundary and is accompanied by a sudden change in the circulating current amplitude, it is marked as an impedance mutation point.

[0103] For the marked impedance mutation points, a joint time-frequency domain analysis of the circulating current signal within the cable section is performed. The Daubechies wavelet basis is used to perform a multi-scale decomposition of the circulating current signal, extracting the amplitude envelope of the high-frequency component. The standard deviation of the high-frequency component amplitude is calculated using a sliding window. If the standard deviation within the window increases suddenly and continuously exceeds the background noise level, it is determined to be a transient current mutation caused by partial discharge or mechanical damage to the sheath. Combined with the cable segment coordinates stored in the cable topology database (including the location of the cross-connection box and the geographic information of the cable well), the time-domain location of the current mutation point is converted to its actual physical location along the cable routing, and the GIS geographic coordinates of the defect point (accurate to the cable well number and distance from the wellhead) are output.

[0104] Finally, live maintenance instructions are generated based on the defect type and GIS coordinates. For sheath damage or wiring errors, the instructions specify that the insulating manipulator carry a sheath repair tool or wiring correction tool. For ground resistance degradation, the instructions include impedance adjustment parameters for the bypass grounding device (such as parallel resistance value and inductance compensation). Simultaneously, the GIS coordinates are converted into the starting and target coordinates of the manipulator's movement path and linked to the navigation system of the live working robot. The maintenance instructions are transmitted to the on-site maintenance terminal via an encrypted communication protocol, triggering the automatic operation sequence of the insulating manipulator and the pre-adjustment of the bypass device.

[0105] As a preferred example, during the live maintenance execution phase, the maintenance instructions generated by the defect analysis module are first received and parsed. The maintenance instructions are encapsulated in a structured data format and include the geographic coordinates of the defect point (based on the latitude, longitude, and elevation data of the GIS system), the maintenance operation type code (such as sheath repair, wiring correction, and grounding resistor replacement), and the impedance adjustment parameters of the bypass grounding device (including the target impedance value and the adjustment rate limit). During the parsing process, the absolute position information of the geographic coordinates is extracted through the instruction decoder, and the maintenance operation type code is matched with the preset operation type database to determine the required maintenance tool type (such as an electric wrench or an insulating sheath hot melt device); at the same time, the impedance adjustment parameters are converted into a control pulse sequence for the adjustable resistor stepper motor of the bypass grounding device and a current setting value for the inductance compensation coil.

[0106] Based on the analyzed maintenance operation type, the insulating robot arm's tool library automatically switches to the corresponding tool via a rotary multi-station fixture: for sheath damage repair, an insulated hot-melt welding gun with constant pressure feedback is used; for cross-connect box wiring anomalies, an insulated screwdriver set with laser alignment is used. Simultaneously, an impedance adjustment command for the bypass grounding device is sent to its control unit. This command contains the initial parameters of the PID control algorithm generated based on the impedance adjustment parameters, which are used to adjust the contact position of the adjustable resistor and the tap position for inductance compensation.

[0107] Based on the geographic coordinates of the defect point, the laser positioning module scans the actual spatial layout of the cable cross-connection section. Combined with the 3D model of the cable routing path (including the absolute coordinates of the cable well and cross-connection box) stored in the cable topology database, the module uses a coordinate transformation algorithm to convert the GIS geographic coordinates into relative positions in the manipulator base coordinate system. The path planning engine calculates a collision-free trajectory based on the relative positions, the manipulator joint kinematic parameters, and the point cloud data of on-site obstacles. It then generates movement instructions containing path node coordinates, joint rotation angle sequences, and velocity curves, and loads them into the manipulator motion controller.

[0108] After controlling the insulating robotic arm to move along the planned path to the defect location, the maintenance tool is activated to perform live operations. For sheath repair, a hot melt welding gun uses gradient heating to weld the damaged sheath under constant pressure, while an infrared thermal imager monitors the temperature distribution in the weld area in real time. For wiring correction, a laser alignment system guides a screwdriver assembly to perform image recognition and torque closed-loop control on the bolts in the cross-connect box. While the robotic arm is operating, the bypass grounding device dynamically adjusts the access impedance based on the impedance adjustment command. A stepper motor drives the slider of the adjustable resistor to change the resistance value. Combined with real-time current data fed back by the Hall effect sensor, a PID algorithm is used to dynamically correct the excitation current of the inductance compensation coil to maintain the system grounding impedance within the set threshold.

[0109] During the maintenance operation, the ground impedance monitoring unit calculates the system impedance amplitude and phase in real time by injecting high-frequency detection signals and measuring the response waveform. When it is detected that the impedance fluctuation exceeds the preset safety range (such as transient changes in the ground loop caused by the operation of the robotic arm), the dynamic compensation mechanism is immediately activated: according to the direction (inductive or capacitive) and amplitude of the impedance deviation, the proportional coefficient and integral time constant of the PID algorithm are adaptively adjusted, and the system impedance is pulled back to the stable range within 200ms by increasing the movement speed of the resistance slider or switching the inductive tap position. This process continues until the robotic arm completes all maintenance actions and the system impedance is stable within the allowable fluctuation range for 10 consecutive seconds, and the maintenance operation is determined to be completed.

[0110] As a specific example, during the precise location of a defect, the circulating current signal of the cable segment where the impedance discontinuity point is located is first divided into pre-set window lengths based on the cross-connection segment lengths and sampling frequencies recorded in the cable topology database. The window lengths are dynamically adapted to the cable segment lengths to ensure that each window corresponds to the physical location of the actual cable segment. For example, for each 50-meter cross-connection cable segment, when collecting circulating current signals at a 1kHz sampling rate, the window length is set to 500 samples (corresponding to a 0.5-second duration), with a 20% overlap between windows to avoid signal truncation.

[0111] The circulating current data within each signal window is subjected to multi-scale decomposition using a Daubechies wavelet basis. The number of decomposition levels is determined based on the typical discharge frequency range of cable sheath defects. Specifically, the high-frequency components (corresponding to the detail coefficients of the first to third layers of the wavelet decomposition) are reconstructed to extract transient pulse signals within a preset frequency band (e.g., 10kHz-100kHz). The root mean square value of the high-frequency components within each window is calculated to obtain a characteristic curve representing the amplitude intensity.

[0112] To identify characteristic amplitude mutation points, a sliding window comparison method is used: the difference in the RMS value of the high-frequency components of adjacent windows is calculated, and a threshold range is dynamically set based on historical data or real-time background noise levels. For example, a valid mutation point is identified when the amplitude difference between adjacent windows exceeds three standard deviations of the RMS value of the background noise. For clusters of consecutive mutation points, their temporal distribution density (the number of mutation points per unit time) is further calculated. If the density exceeds the spatial distribution threshold corresponding to the cable segment length (e.g., more than two mutation points per meter of cable), a local defect is determined in that segment.

[0113] Integrating spatial segmentation information from the cable topology database, the time-domain window sequence is mapped to the actual physical location of the cable. The starting timestamp of each signal window corresponds to the starting position of the cable segment. Based on the cumulative length of the cable laying path (calibrated using laser ranging data) and the window movement step size, a conversion relationship is established between the time-domain window number and the distance between the cable wells. For example, the physical location corresponding to the nth window is "15 meters east of the starting cable well + (n-1) × window step size × cable wave speed." This mapping relationship is used to convert the time-domain distribution of amplitude mutation feature points into the defect segment range within the cable cross-connection segment (e.g., "the section between brackets 3-5 between cable wells A and B").

[0114] Ultimately, the spatial coordinate conversion engine binds the defect area to the GIS geographic coordinates: Based on the cable well longitude and latitude coordinates, the inflection point coordinates of the laying path, and the bracket position offset stored in the cable topology database, a linear interpolation algorithm is used to calculate the absolute geographic coordinates of the defect point. For example, if the defect is located 25 meters east of cable well A (east longitude X, north latitude Y), the output geographic coordinates are east longitude X + 25 × longitude offset coefficient, and north latitude Y + 25 × latitude offset coefficient, with an accuracy of meters. After the coordinates are verified by the topological relationship of the spatial database, a three-dimensional maintenance positioning point containing elevation information is generated and loaded into the navigation system of the live working robot.

[0115] As a preferred example, after completing the live maintenance operation, a closed-loop verification process is started to confirm the defect repair effect. First, the data acquisition process is retriggered: the cable load current, three-phase grounding circulation and grounding resistance data after maintenance are synchronously collected through a distributed fiber optic sensor array and a high-precision Hall sensor. During the acquisition process, the Beidou timing module is used to ensure that the new data set has the same time base as the original acquisition process. At the same time, the latest structural parameters in the preset cable topology database (including the updated sheath size or replacement section length during the maintenance process) are called, and the maintenance section is re-measured through a laser ranging device to dynamically correct the cable length data. Based on the updated structural parameters and real-time data sets, the multi-conductor transmission line equation model is reconstructed, the theoretical circulation distribution value after maintenance is calculated, and a new theoretical circulation map containing the current distribution characteristics of the repair section is generated.

[0116] The new theoretical circulation map is matched and verified with the re-collected measured circulation data: a time-space alignment algorithm is used to perform a secondary calibration of the timestamps and spatial coordinates of the two to ensure data comparability. By calculating the difference values ​​of the circulating currents of each phase in the amplitude and phase dimensions, a difference feature vector for verification is generated. The amplitude difference is expressed as a percentage of the absolute value of the theoretical value and the measured value, and the phase difference is calculated as the angle difference. The preset thresholds are set according to the cable operation regulations, for example, the amplitude difference threshold is set to 5% and the phase difference threshold is set to 3°. If all difference items are below the threshold, a repair success signal is sent to the maintenance terminal and the cable health status database is updated. If any difference item exceeds the limit, the secondary defect location process is triggered.

[0117] When it is determined that the repair is unsuccessful, the iterative repair mechanism is started based on the verification difference feature vector: the amplitude difference and phase difference data that exceed the limit are input into the defect analysis model, and the feature extraction and positioning logic is re-executed. For the phase where the amplitude difference suddenly increases, focus on analyzing the integrity of the sheath of the corresponding cable section (such as whether the hot melt joint is loose); for the persistent phase difference, check whether the wiring sequence of the cross-connection box is corrected in place. The circulating current signal of the abnormal section is analyzed in time and frequency by wavelet transform to identify the high-frequency noise characteristics caused by the secondary defect, and the residual defect point is accurately located in combination with the GIS coordinate mapping algorithm. Generate a maintenance instruction containing the secondary positioning coordinates and correction parameters (such as increasing the compensation inductance of the bypass grounding device or adjusting the operating force of the robotic arm), and re-trigger the path planning and live maintenance operation of the insulating robotic arm until the closed-loop verification is passed.

[0118] The entire verification process is embedded with automated control logic: if two consecutive repair verification attempts fail, the system automatically switches to manual intervention mode, sending an alarm message containing a defect map, repair history, and environmental parameters (temperature, humidity, and vibration data) to the monitoring center. Live operation permissions for that section are also locked. Successful repair results are simultaneously updated to the cloud-based operations and maintenance platform, generating an electronic repair report containing information such as repair time, positioning accuracy, and impedance recovery curves, which serves as the foundation for cable system reliability assessments.

[0119] Example 2

[0120] like Figure 2As shown in Figure 1, the data acquisition module of the live maintenance system for power cable cross-connection grounding systems consists of a distributed fiber optic sensor array and high-precision Hall effect sensors. The distributed fiber optic sensors are installed at preset intervals along the cable cross-connection sections and acquire three-phase grounding loop current data in real time by detecting phase changes in backscattered light from the optical fibers. The Hall effect sensors are integrated within the cross-connection box, and a closed-loop current probe is used to measure the cable load current. Both are synchronized to the microsecond level via a BeiDou timing module. The collected load current, grounding loop current, and metal sheath end-to-end grounding resistance data are transmitted via a wireless transmission network to an edge computing node, generating a real-time dataset with a unified timestamp. This dataset is stored in a cache database based on cable segment number and time sequence.

[0121] The parameter association module uses an API to access a pre-built cable topology database containing standard parameters for the metal sheath inner and outer diameters, phase spacing, and historical maintenance records for different cable types. Combined with real-time cable length measurements from a laser rangefinder in the maintenance section, a dynamic mapping relationship is established: sheath structural parameters are spatially bound to the circulating current data for the corresponding section to form a sheath electromagnetic parameter association set. Cable length and phase spacing parameters are also aligned with load current time series data to construct a cable topology current distribution model. The module outputs a parameter association set consisting of a fused data stream of cable structural feature vectors and real-time electrical parameters.

[0122] The model construction module establishes a multi-conductor transmission line equation model based on an associated parameter set. Specifically, the module considers the impedance distribution parameters of the cable's metal sheath (including resistance, inductance, and capacitance distributions) and the cross-connected segment topology, transforming each sheath segment into a multi-conductor transmission line network. The model uses the measured ground resistance values ​​as boundary conditions, solves the electromagnetic coupling equations using the finite element method, and calculates the theoretical distribution of the inter-sheath current. During the model solution, the inter-conductor potential difference is dynamically adjusted based on real-time load current data, and the electromagnetic coupling coefficient is corrected based on the phase spacing parameter. The resulting output is a theoretical circulating current map corresponding to the cable's physical location. This map stores the circulating current amplitude and phase data for each cable segment in a two-dimensional matrix.

[0123] The defect analysis module receives the theoretical circulation map and the measured circulation data in the real-time data set, and performs spatiotemporal alignment and feature matching: through timestamp calibration and cable space coordinate mapping, the theoretical value and the measured value are aligned according to the same reference, and the amplitude difference absolute value matrix and the phase difference angle matrix are calculated to generate a difference feature vector. Based on the vector, three types of defect features are extracted: for the single-phase circulation direction reversal feature, the vector projection method is used to analyze whether the phase difference exceeds the 150° threshold; for the three-phase deviation uniformity feature, the variance value of the three-phase circulation amplitude difference is calculated and compared with the preset uniformity threshold; for the grounding resistance deviation feature, the measured grounding resistance is compared with the theoretical boundary range to identify the continuously exceeding limit section. The defect type and location determination results are encapsulated as a structured maintenance instruction, which includes geographic coordinates, operation type code and impedance adjustment parameters.

[0124] The insulated manipulator arm of the maintenance execution module utilizes a multi-jointed hydraulic drive structure. Its end features a rotatable tool library with a built-in sheath hot-melt welding gun, an insulated screwdriver set, and an infrared thermal imager. The bypass grounding device consists of an adjustable resistor, an inductance compensation coil, and a high-frequency injection unit. Upon receiving the maintenance command, the command parsing unit decodes the geographic coordinates into three-dimensional coordinates in the manipulator base coordinate system, matches the operation type code to the tool library index table, and activates the rotary fixture to switch to the corresponding tool. The path planning unit, based on on-site environmental data from laser point cloud scanning and the cable topology database's routing path model, uses the A* algorithm to calculate the manipulator's collision-free movement path and outputs control commands containing a sequence of joint angles and a velocity profile. The operation control unit synchronizes the manipulator's movement with the bypass device's adjustments: After the manipulator moves along the planned path to the defect location, it activates the tool to perform the operation (e.g., using a hot-melt welding gun to repair the sheath at a preset temperature gradient). Simultaneously, the bypass device adjusts the slider position of the adjustable resistor and the tap position of the inductance compensation coil based on the impedance adjustment parameters. The dynamic compensation unit monitors the system impedance in real time through high-frequency signal injection. When it detects that the impedance fluctuation exceeds the limit, it triggers the PID control algorithm to dynamically adjust the slider movement speed and inductor excitation current, so that the system impedance returns to the stable range within 200ms until the robot arm completes the operation and the impedance is continuously stable.

[0125] It is understood from common technical knowledge that the present invention may be implemented by other embodiments that do not depart from its spirit or essential features. Therefore, the embodiments disclosed above are, in all respects, merely illustrative and not exclusive. All modifications within the scope of the present invention or equivalent to the scope of the present invention are intended to be encompassed by the present invention.

Claims

1. A live maintenance method for a power cable cross-connection grounding system, characterized in that: The following steps are involved: S1. Synchronously collect the cable line load current, three-phase grounding circulation current, and metal sheath head-end grounding resistance of the cross-connected unit with abnormal circulation current, and generate a real-time data set with a time stamp; S2: Extract cable structure parameters based on the preset cable topology database and dynamically associate them with the real-time data set in step S1 S3. Based on the real-time data set of step S1 and the associated parameters of step S2, a multi-conductor transmission line equation model is constructed, the theoretical circulating current distribution value of each sheath section is calculated, and a theoretical circulating current map is generated; S4. Match and analyze the theoretical circulating current map with the measured circulating current data, and determine the defect type and location based on single-phase polarity reversal, three-phase deviation uniformity, and ground resistance anomaly; S5. Based on the defect location results, maintenance operations are performed under power conditions using an insulated robotic arm, while maintaining the stability of the system grounding impedance through a bypass grounding device.

2. The method according to claim 1, characterized in that The specific steps of synchronous data acquisition in step S1 include: A distributed optical fiber sensor array is laid along the cross-connection section to collect the three-phase ground loop current data of the cable line in real time; A high-precision clock synchronization module is used to align the acquisition timestamps of the load current and the three-phase ground loop current to ensure the timing consistency of different segments of data. The clock synchronization module uses GPS / Beidou dual-mode signals to achieve cross-regional time base unification. The synchronously collected load current, ground loop current, and ground resistance data are transmitted to the central processing unit in real time via a wireless transmission network, generating a real-time data set with a unified time stamp. The real-time data set is used as the input of the circulating current calculation model in step S3 to establish the spatiotemporal correlation between the sheath circulating current and the load current.

3. The live maintenance method for a power cable cross-connection grounding system according to claim 1, characterized in that: The specific steps of obtaining the cable structure parameters and dynamically associating them in step S2 include: Retrieving the metal sheath inner diameter, outer diameter, and phase spacing parameters of the target cross-connection segment based on a preset cable topology database, wherein the database stores standard structural parameters corresponding to different cable models; The length of each cable segment is measured in real time by a laser distance measuring device, and the measured length data is integrated with the standard parameters retrieved from the preset database; A dynamic mapping relationship between the structural parameters and the load current, ground loop current, and ground resistance data collected synchronously in step S1 is established, wherein the mapping relationship includes: Bind the inner diameter and outer diameter parameters of the sheath with the ground loop current data in spatial position to form a sheath electromagnetic parameter association set; The length and phase spacing parameters of each cable segment are time-series aligned with the load current data to generate a cable topology current distribution model; The dynamic mapping relationship is used to synchronously load the sheath structural parameters and the real-time electrical data when constructing the multi-conductor transmission line equation model in step S3, so as to correct the electromagnetic coupling deviation in the theoretical circulating current calculation.

4. The method for live maintenance of a power cable cross-connection grounding system according to claim 1, characterized in that: The specific steps of constructing the multi-conductor transmission line equation model and calculating the theoretical circulating current distribution value in step S3 include: Based on the load current and grounding resistance values ​​collected synchronously in step S1 and the cable structure parameters obtained in step S2, a multi-conductor transmission line equation model is established, where: The multi-conductor transmission line equation model takes the impedance distribution parameters of the cable metal sheath as input, and combines the cross-connected segment topology to make each sheath segment equivalent to a multi-conductor transmission line network; The measured ground resistance value collected in step S1 is introduced into the model as a boundary condition, and the electromagnetic coupling equation of each sheath section is solved by the finite element iteration method to calculate the distribution relationship of the current between the sheaths; Correcting the electromagnetic coupling coefficient between the sheaths based on the phase spacing parameter in step S2, and dynamically adjusting the potential difference between the conductors of the transmission line equation according to the real-time distribution data of the load current; The theoretical circulation distribution value of each section of the sheath is output through iterative calculation to generate a theoretical circulation map corresponding to the spatial position of the cross-connected section; the theoretical circulation map is used to perform spatial matching analysis with the measured circulation data in step S4 to locate the defect position.

5. The method for live maintenance of a power cable cross-connection grounding system according to claim 1, characterized in that: The specific steps of step S4 include: S4.

1. Align the theoretical circulation map generated in step S3 with the measured circulation data collected in step S1 in time and space to generate a difference feature vector containing amplitude difference and phase difference; S4.

2. Based on the difference feature vector, extract the polarity reversal characteristics of the single-phase circulating current direction and the theoretical spectrum, the uniformity characteristics of the three-phase circulating current amplitude deviation, and the deviation characteristics of the ground resistance value from the theoretical boundary; S4.

3. Determine whether the sheath is damaged or the cross-connection box wiring is abnormal based on the polarity reversal feature, determine the ground resistance degradation area based on the uniformity feature, and locate the impedance mutation point based on the deviation feature; S4.

4. Decompose the circulating current signal in the section where the impedance mutation point is located in the time-frequency domain, extract the amplitude mutation characteristics of the high-frequency component through wavelet transform, and output the GIS geographic coordinates of the defect location based on the spatial coordinate data in the cable topology database; S4.

5. Generate a maintenance instruction based on the defect type and GIS geographic coordinates, wherein the maintenance instruction includes the defect location coordinates, the maintenance operation type, and the impedance adjustment parameters of the bypass grounding device.

6. The method for live maintenance of a power cable cross-connection grounding system according to claim 1, characterized in that: The specific steps of step S5 include: S5.

1. Receive the maintenance instruction output in step S4, and analyze the defect location coordinates, maintenance operation type, and impedance adjustment parameters in the maintenance instruction; S5.

2. According to the maintenance operation type, call a corresponding maintenance tool from the tool library of the insulating manipulator, and generate an impedance adjustment instruction for the bypass grounding device based on the impedance adjustment parameter; S5.

3. Generate a moving path planning instruction for the insulation manipulator based on the defect location coordinates and the spatial mapping relationship between the laser positioning module and the cable topology database; S5.

4. After the insulating manipulator moves along the path to the defect location, the maintenance tool is activated to perform live operation, and the access impedance of the bypass grounding device is dynamically adjusted according to the impedance adjustment instruction; S5.

5. During the maintenance operation, the impedance changes of the grounding system are monitored in real time. When the impedance fluctuation is detected to exceed the preset threshold, the dynamic compensation mechanism of the bypass grounding device is triggered until the maintenance operation is completed and the system impedance returns to stability.

7. A live maintenance method for a power cable cross-connection grounding system according to claim 5, characterized in that: The specific steps of extracting the high-frequency component amplitude mutation characteristics by wavelet transform in step S4.4 include: S4.4.

1. Extract the time domain waveform sequence and divide the signal window based on the circulating current signal in the section where the impedance mutation point is located; S4.4.

2. Perform multi-scale wavelet decomposition on the circulation data of each signal window to separate the high-frequency components within a preset frequency band; S4.4.

3. Calculate the difference in the high-frequency component amplitudes of adjacent windows. If the difference exceeds the dynamic threshold range, mark it as an amplitude mutation feature point. S4.4.

4. Determine the physical segment of the defect in the cable cross-connection segment based on the time domain distribution density of the amplitude mutation characteristic points and the spatial segmentation information in the cable topology database; S4.4.

5. Spatial mapping of the physical segment with the GIS geographic coordinates is performed to output the precise geographic coordinates of the defect location.

8. The method for live maintenance of a power cable cross-connection grounding system according to claim 1, characterized in that: The step S5 also includes a closed-loop verification step S6: S6.

1. After the live maintenance operation is completed in step S5, steps S1 to S3 are re-executed to generate a theoretical circulation diagram after maintenance; S6.

2. Match and analyze the theoretical circulation map after repair with the measured circulation data collected again in step S1. If the amplitude difference and phase difference in the difference feature vector are both less than the preset threshold, the defect repair is determined to be successful; S6.

3. If it is determined that the defect is not repaired successfully, the defect location logic of step S4 is triggered based on the difference feature vector of step S6.2, a secondary repair instruction is generated and the process returns to step S5 for execution.

9. A live maintenance system for a power cable cross-interconnected grounding system, based on a live maintenance method for a power cable cross-interconnected grounding system according to any one of claims 1 to 8, characterized in that: include: The data acquisition module is used to synchronously collect the cable line load current, three-phase grounding circulation current, and metal sheath head-end grounding resistance of the cross-connected units with abnormal circulation current, and generate a real-time data set with a time stamp; A parameter association module, connected to the data acquisition module, for extracting cable structure parameters based on a preset cable topology database and dynamically associating them with the real-time data set; a model construction module, connected to the parameter association module, for constructing a multi-conductor transmission line equation model based on the real-time data set and the associated parameters, calculating the theoretical circulating current distribution value of each section of the sheath, and generating a theoretical circulating current map; a defect analysis module, connected to the model building module, for matching and analyzing the theoretical circulating current map with the measured circulating current data, and determining the defect type and location based on single-phase polarity reversal, three-phase deviation uniformity, and ground resistance anomaly; The maintenance execution module is connected to the defect analysis module and includes an insulating mechanical arm and a bypass grounding device. It is used to perform maintenance operations in a live state according to the defect location results, and maintain the stability of the system grounding impedance by dynamically adjusting the access impedance of the bypass grounding device.

10. The live maintenance system for a power cable cross-connection grounding system according to claim 9, characterized in that: The maintenance execution module includes: An instruction parsing unit, configured to receive the repair instruction output by the defect analysis module and parse the defect location coordinates, repair operation type, and impedance adjustment parameters; a tool calling unit, connected to the instruction parsing unit, for calling a corresponding maintenance tool from a tool library of the insulating manipulator according to the maintenance operation type, and generating an impedance adjustment instruction for the bypass grounding device; A path planning unit, connected to the instruction parsing unit, is used to generate a moving path planning instruction for the insulation manipulator based on the spatial mapping relationship between the defect location coordinates and the cable topology database; An operation control unit, connected to the path planning unit and the tool calling unit, is used to control the insulating manipulator to move along the planned path to the defect location, start the maintenance tool to perform the operation, and synchronously trigger the impedance dynamic adjustment of the bypass grounding device; The dynamic compensation unit is used to monitor the impedance changes of the grounding system in real time. When the impedance fluctuation exceeds the preset threshold, the compensation mechanism of the bypass grounding device is triggered to maintain the system impedance stability until the maintenance is completed.

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