Current collection cable line fault positioning and hidden danger identification method, system and device, and medium

Abstract

The invention discloses a current collection cable line fault positioning and hidden danger identification method, system and device and a medium, and belongs to the technical field of current collection cable line fault analysis, and the method comprises the steps: setting a plurality of measuring points on a current collection cable line to collect fault traveling wave signals, and obtaining the traveling wave current waveform of each measuring point; acquiring dielectric constant distribution and dielectric loss factor distribution of each cable section by analyzing propagation characteristics of traveling wave current waveforms among different measuring points; taking the dielectric constant and the dielectric loss factor as two-dimensional feature vectors, and calculating an insulation degradation index of each cable section through coupling analysis; dividing a degradation section according to the numerical distribution of the insulation degradation index; determining the coordinates of a fault breakdown point according to the polarity reversal position of the traveling wave current waveform; and marking a first-level insulation hidden danger point and a second-level insulation hidden danger area. According to the method, the problem of positioning errors caused by constant wave velocity hypothesis is solved, and the fault positioning precision and the hidden danger recognition accuracy are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of fault analysis technology for power collection cable lines, specifically to a method, system, equipment, and medium for fault location and hidden danger identification of power collection cable lines. Background Technology

[0002] With the rapid growth of installed capacity of new energy sources such as wind power and photovoltaics, the reliability of collector cables, as the key link connecting power generation units and substations, directly affects the power generation efficiency and economic benefits of power plants. Collector cables are subjected to the combined effects of electrical, thermal, mechanical stresses, and environmental factors over long periods, leading to gradual aging and deterioration of the insulation, which may eventually cause breakdown faults and large-scale downtime losses. Therefore, accurately identifying potential insulation defects in cables and quickly locating fault points are core requirements for the operation and maintenance management of new energy power plants.

[0003] Existing technologies mainly employ offline detection methods, such as dielectric loss angle testing and partial discharge detection. These require power outages and can only assess the state at a single measurement moment, making continuous monitoring difficult. In recent years, traveling wave online monitoring technology has emerged, utilizing transient traveling wave signals generated by cable faults to locate the fault. However, it has the following shortcomings: First, traveling wave location depends on wave velocity parameters, but cable aging causes changes in the dielectric constant, resulting in spatial non-uniformity of the wave velocity. Traditional methods, assuming a constant wave velocity, introduce significant errors. Second, existing methods only perform post-fault location, lacking the ability to pre-assess the cable insulation condition and thus failing to provide early fault warnings. Third, the dielectric constant and loss factor, as two key parameters characterizing insulation condition, exhibit complex coupled evolutionary relationships during cable degradation; analyzing only one parameter cannot comprehensively reflect the insulation health status. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention provides a method, system, equipment and medium for fault location and hidden danger identification of current collector cable lines.

[0005] Therefore, the technical problem solved by this invention is that existing current collector cable monitoring technologies cannot simultaneously achieve accurate assessment of insulation degradation and accurate location of fault points. Specifically, traveling wave positioning results in large errors due to ignoring the spatial differences in wave velocity caused by cable aging; single dielectric parameter assessment cannot fully reflect the characteristics of insulation coupling degradation; there is a lack of risk area identification methods based on degradation propagation mechanisms; and there is a disconnect between post-fault location and pre-fault hazard warning.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for fault location and hidden danger identification of current collector cable lines, comprising, Multiple measuring points are set up on the collector cable line to collect fault traveling wave signals and obtain the traveling wave current waveform at each measuring point. By analyzing the propagation characteristics of the traveling wave current waveform at different measurement points, the dielectric parameter distribution of each cable segment is obtained. The dielectric parameter distribution includes the dielectric constant distribution and the dielectric loss factor distribution. The dielectric constant and dielectric loss factor of each cable segment are used as two-dimensional feature vectors. By coupling analysis of the degree of abnormality of the dielectric constant and the degree of abnormality of the dielectric loss factor, the insulation degradation index of each cable segment is calculated. Based on the numerical distribution of the insulation degradation index, each cable segment is divided into high-risk degradation segment, medium-risk degradation segment, and low-risk degradation segment. Within the high-risk degradation range, the coordinates of the fault breakdown point are determined based on the location where the polarity of the traveling wave current waveform reverses. The locations in the high-risk deterioration section, excluding the location of the fault breakdown point, are marked as first-level insulation hazard points, and the medium-risk deterioration section is marked as a second-level insulation hazard area.

[0007] As a preferred embodiment of the method for fault location and hidden danger identification of a current collector cable line according to the present invention, the step of obtaining the distribution of dielectric parameters of each cable segment by analyzing the propagation characteristics of the traveling wave current waveform between different measuring points includes performing time-domain analysis on the traveling wave current waveform and extracting the arrival time difference of the traveling wave between adjacent measuring points. Based on the travel wave arrival time difference and the cable segment length between adjacent measuring points, the equivalent travel wave propagation speed of each cable segment is calculated. Based on the equivalent traveling wave propagation speed, the dielectric constant distribution of each cable segment is inverted through the physical relationship between electromagnetic wave propagation speed and dielectric constant.

[0008] As a preferred embodiment of the method for fault location and hidden danger identification of a current collector cable line according to the present invention, the step of obtaining the distribution of dielectric parameters of each cable segment by analyzing the propagation characteristics of the traveling wave current waveform at different measuring points further includes performing frequency domain transformation on the traveling wave current waveform to obtain the traveling wave spectrum at each measuring point. Extract the energy of the preset frequency band in the traveling wave spectrum and calculate the attenuation ratio of the preset frequency band energy between adjacent measurement points; Based on the attenuation ratio, the distribution of the dielectric loss factor of each cable segment is inverted by using the attenuation law of electromagnetic waves in the loss medium.

[0009] As a preferred embodiment of the fault location and hidden danger identification method for a current collector cable line according to the present invention, the calculation of the insulation degradation index of each cable segment includes constructing an insulation health evolution baseline in a two-dimensional feature space based on the dielectric constant distribution and the dielectric loss factor distribution. For any cable segment, the actual state point of the segment is determined in the two-dimensional feature space using the dielectric constant value corresponding to the dielectric constant distribution and the dielectric loss factor value corresponding to the dielectric loss factor distribution of the segment as coordinate components. Calculate the vertical deviation distance between the actual state point and the insulation health evolution baseline; Calculate the degradation risk amplification factor based on the coordinates of the actual state point in the dielectric constant dimension; Multiplying the vertical deviation distance by the degradation risk amplification factor yields the insulation degradation index of the cable segment.

[0010] The beneficial effects of this preferred technical solution are as follows: By mapping the abnormal states of dielectric constant and loss factor to a single evaluation index through vertical deviation distance, it can simultaneously identify multiple degradation modes such as synchronous anomalies of both parameters, single parameter anomalies, and correlational anomalies between parameters, overcoming the assessment bias caused by setting thresholds separately in existing technologies. Dynamic weighting is achieved through a degradation risk amplification factor, assigning a higher degradation index to cable sections at the end of degradation, which conforms to the physical law of nonlinear increase in insulation breakdown probability, overcoming the problem of insufficient risk differentiation at different degradation stages in linear scoring methods.

[0011] As a preferred embodiment of the fault location and hidden danger identification method for a current collector cable line according to the present invention, the step of dividing each cable segment into high-risk deterioration segment, medium-risk deterioration segment and low-risk deterioration segment according to the numerical distribution of the insulation deterioration index includes, based on the numerical similarity of the insulation deterioration index of each cable segment, aggregating cable segments with similar insulation deterioration indices into multiple cable segment groups. Calculate the arithmetic mean of the insulation degradation index of each cable segment within the cable segment group, and use it as the group degradation index of the cable segment group; Based on the numerical range of the group deterioration index, a preliminary risk level is determined for the cable segment group to obtain a preliminary risk level. Extract the vertical deviation distance of each cable segment within the cable segment group during the calculation of the insulation degradation index, and calculate the maximum value of the vertical deviation distance within the cable segment group; When the maximum value of the vertical deviation distance exceeds the preset abnormal deviation threshold, the preliminary risk level is increased by one level to obtain the final risk level; The final risk level is assigned to each cable segment within the cable segment group.

[0012] As a preferred embodiment of the fault location and hidden danger identification method for a power collection cable line according to the present invention, wherein: based on the numerical similarity of the insulation degradation index of each cable segment, cable segments with similar insulation degradation indices are aggregated into multiple cable segment groups, and according to the spatial order of the power collection cable line, a continuous degradation area in which the insulation degradation index of N or more consecutive cable segments exceeds a preset degradation identification threshold is identified. For each of the continuous deterioration areas, the cable segment with the largest insulation deterioration index within the continuous deterioration area is identified as a suspected deterioration source segment; Centered on the suspected deterioration source segment, the judgment is extended to the adjacent cable segments in front and behind. When the insulation deterioration index of the adjacent cable segment is greater than the deterioration identification threshold, or when the difference in the insulation deterioration index between the adjacent cable segment and the suspected deterioration source segment is less than the preset gradient threshold, the adjacent cable segment is included in the continuous deterioration area. Repeat the extended determination until neither of the adjacent cable segments at the two ends of the continuously deteriorated area meets the inclusion condition, and then aggregate all the cable segments in the continuously deteriorated area into a cable segment group. For the remaining cable segments that are not included in any of the continuous degradation regions, the coordinate values ​​of the actual state points of the remaining cable segments in the dielectric constant dimension during the calculation of the insulation degradation index are extracted. The remaining cable segments are divided into corresponding degradation stages according to the coordinate values. The remaining cable segments that belong to the same degradation stage and whose insulation degradation indices differ by less than a preset threshold are aggregated into a cable segment group.

[0013] As a preferred embodiment of the fault location and hidden danger identification method for a current collector cable line according to the present invention, the step of determining the fault breakdown point coordinates based on the location where the polarity of the traveling wave current waveform reverses includes calculating the traveling wave propagation velocity of each cable segment based on the dielectric constant distribution of each cable segment and establishing a segmented wave velocity model of the current collector cable line. The polarity reversal feature of the traveling wave current waveform is detected, and the measured propagation time of the traveling wave from the fault point to the monitoring endpoint is extracted; For each high-risk deterioration segment, the location with the largest insulation deterioration index within that segment is taken as the initial candidate point of the fault. Based on the segmented wave velocity model, the theoretical propagation time of the traveling wave from the initial candidate point of the fault to the monitoring endpoint is calculated. Calculate the time error between the theoretical propagation time and the measured propagation time. When the time error is greater than the preset time tolerance, adjust the position of the initial candidate point of the fault along the spatial direction of the high-risk deterioration segment according to the positive or negative sign of the time error to obtain the updated candidate point position. Based on the updated candidate point position, repeat the steps of calculating the theoretical propagation time and adjusting the candidate point position until the time error is less than or equal to the time tolerance, and use the candidate point position at this time as the coordinates of the fault breakdown point. When there are multiple high-risk deterioration segments, the iterative localization process is performed for each high-risk deterioration segment, and the candidate point with the smallest final time error is selected as the coordinate of the fault breakdown point.

[0014] The beneficial effects of this preferred technical solution are as follows: It overcomes the positioning error problem caused by the assumption of a constant wave velocity in existing technologies by using a segmented wave velocity model, adapts to the spatial non-uniformity of wave velocity caused by cable aging, and significantly improves the accuracy of fault location. An iterative positioning algorithm is used to achieve adaptive correction of the fault location without manual parameter intervention. A multi-segment competition mechanism accurately locates the actual fault segment, and the reliability of each candidate location is evaluated through the final time error, providing a quality evaluation index for the positioning results.

[0015] This invention provides a fault location and hidden danger identification system for power collection cable lines.

[0016] To solve the above technical problems, the present invention provides the following technical solution: a fault location and hidden danger identification system for a collector cable line, comprising: a data acquisition module, used to set up multiple measuring points on the collector cable line to collect fault traveling wave signals and obtain the traveling wave current waveform of each measuring point; The feature analysis module is used to obtain the dielectric parameter distribution of each cable segment by analyzing the propagation characteristics of the traveling wave current waveform at different measurement points. The dielectric parameter distribution includes the dielectric constant distribution and the dielectric loss factor distribution. The coupling analysis module is used to take the dielectric constant and dielectric loss factor of each cable segment as two-dimensional feature vectors, and calculate the insulation degradation index of each cable segment by coupling analysis of the degree of abnormality of the dielectric constant and the degree of abnormality of the dielectric loss factor. The degradation analysis module is used to divide each cable segment into high-risk degradation segment, medium-risk degradation segment, and low-risk degradation segment according to the numerical distribution of the insulation degradation index. The fault location module is used to determine the coordinates of the fault breakdown point based on the location where the polarity of the traveling wave current waveform reverses within the high-risk deterioration section. The hazard analysis module is used to mark the remaining locations in the high-risk deterioration section, excluding the location of the fault breakdown point, as first-level insulation hazard points, and to mark the medium-risk deterioration section as second-level insulation hazard areas.

[0017] The present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, characterized in that the processor executes the computer program to implement the steps of the method for locating faults and identifying potential hazards in a power distribution cable line.

[0018] The present invention provides a computer-readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, it implements the steps of the method for locating faults and identifying potential hazards in a current collector cable line.

[0019] The beneficial effects of this invention are as follows: by constructing an insulation health evolution baseline in a two-dimensional feature space and calculating the vertical deviation distance and degradation risk amplification factor of the actual state point, coupled analysis of dielectric constant and loss factor is realized.

[0020] By identifying continuously deteriorating areas, locating suspected deterioration sources, and dynamically expanding the scope of influence, this approach conforms to the physical propagation laws of cable insulation degradation. Compared to existing general clustering methods based on numerical similarity, it can effectively distinguish between propagating and isolated degradation, improving the targeted nature of risk area delineation.

[0021] Based on the dielectric constant distribution obtained from degradation assessment, the traveling wave propagation velocity of each cable segment is inferred. An iterative positioning algorithm is then used to match the theoretical propagation time with the measured propagation time. This overcomes the positioning error problem caused by the assumption of a constant wave velocity in existing technologies, adapts to the spatial non-uniformity of wave velocity caused by cable aging, and significantly improves the accuracy of fault location. Simultaneously, through the iterative adjustment process of candidate point positions, the deviation between the actual and predicted wave velocities can be identified in reverse, demonstrating a self-detection capability for degradation anomalies. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The above is a flowchart of a method for locating faults and identifying potential hazards in a current collector cable line, provided as an embodiment of the present invention. Detailed Implementation

[0024] To make the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0025] Example 1, referring to Figure 1 This is one embodiment of the present invention, which provides a method for fault location and hazard identification in a current collector cable line, including: Step 1: Set up multiple measuring points on the collector cable line to collect fault traveling wave signals and obtain the traveling wave current waveform at each measuring point; Step 2: By analyzing the propagation characteristics of the traveling wave current waveform at different measurement points, the dielectric parameter distribution of each cable segment is obtained. The dielectric parameter distribution includes the dielectric constant distribution and the dielectric loss factor distribution. Step 3: Using the dielectric constant and dielectric loss factor of each cable segment as two-dimensional feature vectors, and through coupling analysis of the degree of abnormality of the dielectric constant and the degree of abnormality of the dielectric loss factor, calculate the insulation degradation index of each cable segment. Step 4: Based on the numerical distribution of the insulation degradation index, divide each cable segment into high-risk degradation segment, medium-risk degradation segment, and low-risk degradation segment; Step 5: Within the high-risk degradation range, determine the coordinates of the fault breakdown point based on the location where the polarity of the traveling wave current waveform reverses; Step 6: Mark the remaining locations in the high-risk deterioration section, except for the location of the fault breakdown point, as first-level insulation hazard points, and mark the medium-risk deterioration section as second-level insulation hazard areas.

[0026] This embodiment provides a solution to the technical challenges faced in assessing insulation degradation and locating faults in current collector cables. In existing technologies, traveling wave location methods typically assume a constant wave velocity parameter along the entire cable. However, during long-term operation, local aging, moisture absorption, or temperature differences cause spatial variations in the dielectric constant, resulting in a non-uniform distribution of the actual wave velocity. Using constant wave velocity calculations will introduce cumulative errors, making it difficult to meet the accuracy requirements of on-site maintenance. Furthermore, existing insulation condition assessment methods often rely on single parameter thresholds for dielectric constant or loss factor, failing to fully explore the coupled evolution characteristics of these two parameters during the degradation process, leading to insufficient ability to identify early degradation or abnormal degradation patterns. In addition, cable degradation often exhibits spatial continuity and propagation, with degradation spreading between adjacent cable sections. However, existing clustering methods only group based on numerical similarity, neglecting the location of degradation sources and the dynamic expansion of the impact range, making it difficult to provide accurate data for regional maintenance. In this embodiment, the parameters of each segment of the medium are extracted by analyzing the traveling wave propagation characteristics in step 2, the degradation index is calculated by two-dimensional coupling analysis in step 3, risk classification is performed by combining spatial continuity in step 4, and the wave velocity is corrected and the fault point is iteratively located by using the degradation assessment results in step 5, thus realizing the deep integration of degradation assessment and fault location.

[0027] This embodiment establishes a complete technical chain from data acquisition, degradation assessment, risk classification to fault location and hazard marking. Step 1: By deploying measuring points at key locations of the power line, online continuous monitoring is achieved using the transient characteristics of traveling wave signals, without the need for power outages. Step 2: Based on the arrival time difference and energy attenuation characteristics of the traveling wave between different measuring points, the dielectric constant and loss factor distribution of each cable segment are obtained through inversion, converting the transient signal into quantifiable dielectric parameters. Step 3: A two-dimensional feature space is constructed. By calculating the degree of deviation of the state point from the healthy evolution trajectory and introducing a dynamic amplification factor, an insulation degradation index that comprehensively reflects the abnormal state of both parameters is generated, improving the comprehensiveness and accuracy of degradation identification. Step 4: By identifying continuous degradation areas, locating degradation sources, and dynamically expanding the scope of influence, combined with group assessment and deviation distance verification mechanisms, cable segments are scientifically divided into different risk levels, providing a basis for differentiated maintenance strategies. Step 5: A segmented wave velocity model is established using the dielectric constant distribution obtained from the degradation assessment. An iterative algorithm is used to adaptively correct the location of fault candidate points, overcoming the limitations of the constant wave velocity assumption and significantly improving the location accuracy. Step 6 marks potential hazards based on risk level and fault location, forming a closed-loop management system from early warning to location, thus realizing a shift from a passive emergency repair to a proactive prevention-based operation and maintenance model.

[0028] Example 2, an embodiment of the present invention, provides a method for fault location and hidden danger identification of power collection cable lines based on the previous embodiment, including: Step 1: Set up multiple measuring points on the collector cable line to collect fault traveling wave signals and obtain the traveling wave current waveform at each measuring point, including the following steps A1-A3: A1: Multiple measuring points are installed along the power collection cable line. The spacing between the measuring points is determined based on the total length of the line and the required monitoring accuracy. A traveling wave current sensor is installed at each measuring point. The traveling wave current sensor uses a Rogowski coil or a high-frequency current transformer to capture transient current signals in the cable.

[0029] A2: When an insulation breakdown fault occurs in the collector line, the transient current traveling wave generated at the fault point propagates along the cable to both ends, and the traveling wave current sensors at each measuring point synchronously collect the current signal. The collected analog signal is amplified and filtered by the signal conditioning circuit, and then converted into a digital signal by the analog-to-digital converter.

[0030] A3: Digital signals from all measuring points are transmitted to the monitoring master station in real time via the communication network. The monitoring master station performs time synchronization calibration on the traveling wave current waveforms uploaded by each measuring point, and uses a satellite time synchronization system to ensure the consistency of the time reference of each measuring point. After time alignment, traveling wave current waveform data of each measuring point on the same time axis are obtained.

[0031] In this embodiment of the application, in step 1, multiple measuring points are set up: a starting measuring point is set at the outlet of the booster station at the beginning of the collector cable line, a terminal measuring point is set at the grid connection point of the wind turbine at the end of the line, and an intermediate measuring point is set every three cable segments along the cable line between the beginning and the end. The cable segments are divided by cable joints.

[0032] A Rogowski coil-type traveling wave current sensor is installed at each measuring point, with the Rogowski coil fitted between the cable sheath and the grounding wire. The output of the Rogowski coil is connected to a signal conditioning module, which includes a preamplifier, a bandpass filter, and a programmable gain amplifier. The output of the signal conditioning module is connected to a data acquisition card, which converts the analog signal into a digital signal via an analog-to-digital converter.

[0033] The data acquisition card connects to the measurement point controller, which is equipped with a satellite timing receiver module to receive BeiDou or GPS satellite signals for time calibration. The measurement point controller uploads timestamped traveling wave current waveform data to the monitoring master station. The monitoring master station performs time alignment of the waveform data from each measurement point based on the timestamps to determine the direction of traveling wave propagation and the time difference of arrival of the traveling wave between each measurement point.

[0034] In an optional implementation, step 1 can be achieved by setting multiple measuring points: one measuring point at each cable joint location of the collector cable line, and an additional measuring point at the midpoint of the cable segment between two adjacent joints. The cable joint locations are the connection points between cable reels.

[0035] A high-frequency current transformer is installed at each measuring point, and the high-frequency current transformer is installed on the grounding lead of the cable. The output of the high-frequency current transformer is connected to a signal acquisition device, which converts the analog signal into a digital signal and then uploads it to the monitoring master station via a wireless communication module.

[0036] The signal acquisition devices at each measuring point achieve time synchronization by receiving satellite timing signals. The monitoring master station aligns the received waveform data from each measuring point according to the timestamp to obtain the time-synchronized traveling wave current waveform.

[0037] In another optional implementation, step 1, setting multiple measuring points can also be achieved by dividing the cable line into high-concern areas and regular areas based on its actual length and historical operating conditions. The high-concern areas include older sections with over ten years of service life, sections with historical faults, and sections traversing high-humidity or high-temperature environments. In the high-concern areas, one measuring point is set every other cable segment; in the regular areas, one measuring point is set every five cable segments.

[0038] A combined sensor is installed at each measuring point, which includes both a traveling wave current acquisition unit and a partial discharge detection unit. The output of the combined sensor is connected to an edge computing gateway, which preprocesses the acquired signals and then uploads them to the monitoring master station via a mobile communication network. Each measuring point synchronizes its clock with the monitoring master station using the Network Time Protocol (NTP) to ensure consistency of time reference across all measuring points.

[0039] Step 2: By analyzing the propagation characteristics of the traveling wave current waveform at different measurement points, the dielectric parameter distribution of each cable segment is obtained. The dielectric parameter distribution includes the dielectric constant distribution and the dielectric loss factor distribution, including the following steps B1-B6: B1: Perform time-domain analysis on the traveling wave current waveform and extract the arrival time difference of the traveling wave between adjacent measurement points; B2: Based on the travel wave arrival time difference and the cable segment length between adjacent measuring points, calculate the equivalent travel wave propagation speed of each cable segment; B3: Based on the equivalent traveling wave propagation speed, the dielectric constant distribution of each cable segment is inverted through the physical relationship between electromagnetic wave propagation speed and dielectric constant.

[0040] B4: Perform frequency domain transformation on the traveling wave current waveform to obtain the traveling wave spectrum at each measurement point; B5: Extract the energy of the preset frequency band in the traveling wave spectrum, and calculate the attenuation ratio of the preset frequency band energy between adjacent measuring points. The attenuation ratio characterizes the degree of attenuation of the high-frequency components of the traveling wave during its propagation in the cable segment. B6: Based on the attenuation ratio, the distribution of the dielectric loss factor of each cable segment is inverted by using the attenuation law of electromagnetic waves in the loss medium.

[0041] In this embodiment of the application, in step B3, the dielectric constant distribution of each cable segment is inverted by: According to the theory of electromagnetic wave propagation in a medium, the propagation speed of a traveling wave is... relative permittivity of the medium The following conditions must be met: in The speed at which a traveling wave propagates in the cable insulation medium. The speed of light in a vacuum is the relative permittivity of the cable insulation medium.

[0042] Transforming the above equation yields the inverse formula for the dielectric constant: Step B3-2: Establish the correlation equation between the dielectric constant of each segment and the time difference between the measurement points. (Set the measurement points...) With measuring points Between contains the first Section of cable, among which Number the measurement points. The starting cable segment number of this measuring point interval meets the following requirements. . No. The length of the cable segment is The dielectric constant is ,in Number the cable segment.

[0043] Traveling wave passes through the first The propagation speed of the cable segment is The propagation time of the traveling wave through this segment is: in For the traveling wave to pass through the first The propagation time of a section of cable.

[0044] Extracted travel wave arrival time difference between adjacent measuring points It equals the sum of the propagation times of the traveling wave through each cable segment within the interval of that measuring point: in For the extracted measurement points With measuring points The time difference in arrival of the traveling waves between them.

[0045] Define a column vector consisting of the square roots of the dielectric constants of each cable segment to be inverted: in Let be the vector of square roots of the dielectric constant. This represents the total number of cable segments in the line. This represents the transpose of a vector. For the first The dielectric constant of a section of cable.

[0046] Define a column vector consisting of the product of the time difference between each measurement point extracted in step B1 and the speed of light: in Given a vector of quantities, This represents the total number of measurement points along the line. The measurement points extracted in step B1 With measuring points The time difference in arrival of the traveling waves between them.

[0047] Establish a system of linear equations: in The coefficient matrix has dimensions of . .

[0048] coefficient matrix Construction method: The first Row corresponding measurement point interval (measuring point) With measuring points (between), the interval between measurement points includes the first If the cable segment is given, then the element in that row is: in Representation matrix The Line 1 Column elements, These represent the cable segment lengths between adjacent measuring points combined in step B2. The remaining positional elements in this row are... .

[0049] Since the number of equations is The unknown quantity is This system of equations is an underdetermined system of equations, and additional constraints need to be introduced to solve it.

[0050] Based on the physical laws of cable insulation aging, the dielectric constant of adjacent cable sections exhibits a gradual distribution along the line. Introducing a smoothing constraint, a Tikhonov regularization objective function is constructed: in Let be the regularization objective function. This represents the square of the 2-norm of a vector, which is the sum of the squares of all its elements. The first term... This is the data fitting term, measuring the deviation between the calculated value and the traveling wave arrival time difference extracted in step B1. (Second term) To smooth the constraint term, It is a first-order difference matrix with dimension . The difference matrix of the first... OK The elements are: in Representation matrix The Line 1 The matrix is ​​composed of columns, with all other elements being 0. It calculates the difference between the square roots of the dielectric constant of adjacent segments. This is a regularization parameter that controls the balance between the accuracy of data fitting and the smoothness of the solution.

[0051] Selecting candidate regularization parameter sequences ,in .

[0052] For each candidate parameter Solving the minimization problem The solution is obtained ,in For parameters The corresponding solution vector.

[0053] Calculate the residual norm corresponding to the solution. and smoothness norm ,in Indicates the first The residual norm corresponding to each parameter Indicates the first The smoothness norm corresponding to each parameter.

[0054] Mark points in a log-log coordinate system ,in It represents a logarithm with base 10.

[0055] Calculate the curvature of the curve. For the Points ,set up The curvature is: in For the first The curvature at a point, The x-coordinates of three adjacent points are: This represents the corresponding ordinate.

[0056] Select the point with the greatest curvature, i.e. Corresponding As the optimal regularization parameter.

[0057] Initialization vector ,in Let be the initial solution vector, with the superscript (0) indicating the 0th iteration, and 2.3 being the nominal dielectric constant of the cross-linked polyethylene cable.

[0058] No. iteration (for iteration number) Calculate the gradient of the objective function at the current point: in For the first The gradient vector of the next iteration. For matrix transpose, For matrix transpose, For the first The solution vector for the nth iteration.

[0059] Calculate the conjugate search direction: in For the first The search direction for the next iteration. For the first The search direction for the next iteration. For conjugate coefficients: in This represents the transpose of the gradient vector. Represents the vector dot product. For the first The gradient vector for the first iteration. .

[0060] Line search to determine step size : Initialize step size Verify the Armijo condition: in If the condition is not met, the step size is reduced. ,in This indicates an assignment update, with 0.5 as the step size reduction factor. The check is repeated until the condition is met.

[0061] Update the solution vector: in For the first The solution vector of the nth iteration. For the first The step size determined in the next iteration.

[0062] Determine the harvest: Calculate the relative change: in For the first The relative change in each iteration. When The iteration terminates at time, where The convergence interval is denoted as .

[0063] The dielectric constant of each cable segment is obtained by squaring each element of the convergent solution: in For convergent solution vectors The One element, For the first The dielectric constant obtained by inversion of a section of cable.

[0064] Calculate the average dielectric constant gradient of the internal segment: in For the average gradient, For the first Section and the The difference in dielectric constant between the first and last segments. Correcting the dielectric constants of the first and last segments: in The dielectric constant is corrected to the value in paragraph 1. Revised to the first The corrected dielectric constant.

[0065] After fixing the corrected boundary values, repeat steps B3-4 to B3-6 for the internal segments to obtain the final dielectric constant distribution of each cable segment. .

[0066] In an optional implementation, in step B3, the dielectric constant distribution of each cable segment can be inverted by: Based on the physical relationship between the propagation speed of electromagnetic waves and the dielectric constant, the equivalent dielectric constant at each measuring point interval is calculated. The calculation method is to divide the square of the speed of light by the square of the equivalent traveling wave propagation speed.

[0067] Statistical analysis was performed on the calculated equivalent traveling wave propagation velocity. The arithmetic mean of the equivalent velocities at all measuring point intervals was calculated by summing the velocities at each interval and dividing by the total number of measuring point intervals. The standard deviation was calculated by first finding the difference between the velocity at each interval and the mean, then summing the squares of these differences, dividing by the total number of measuring point intervals, and taking the square root. Measuring point intervals with abnormal velocities were identified based on the criterion that the absolute value of the difference between the equivalent velocity and the mean was greater than twice the standard deviation.

[0068] The line is divided into zones based on the spatial distribution of equivalent speed. The rate of change of speed between adjacent measuring points is calculated by subtracting the speed between the previous and subsequent measuring points, and then dividing the difference by the average speed. When the absolute value of the rate of change of speed between three or more consecutive measuring point intervals is less than 0.05, these measuring point intervals are classified as the same section.

[0069] For each segment, it is assumed that the dielectric constant follows a linear distribution. The dielectric constant distribution of the entire segment is characterized by two parameters: the dielectric constant at the starting point and the dielectric constant at the ending point. The dielectric constant at any position within the segment is calculated using linear interpolation. The interpolation method is that the dielectric constant at the current position equals the dielectric constant at the starting point plus the difference between the dielectric constant at the ending point and the dielectric constant at the starting point, multiplied by the ratio of the distance from the current position to the starting point to the total length of the segment.

[0070] Establish the inversion equation for the dielectric constant of the section. Substitute the linear distribution assumption into the traveling wave propagation time equation for all measurement point intervals covered by the section. The traveling wave propagation time equation is derived from the established correlation equation between the dielectric constant of each section and the time difference between the measurement point intervals. Establish a system of equations concerning the dielectric constants at the start and end points of the section, with the number of equations equal to the number of measurement point intervals included in the section.

[0071] The least squares method is used to solve the system of equations. The goal of the least squares method is to minimize the sum of squares of the equation residuals. This is done by taking the partial derivatives of the dielectric constants at the starting and ending points and setting them to zero, resulting in a linear equation containing two unknowns. Solving this linear equation yields the dielectric constant values ​​of the segment boundaries.

[0072] A continuity constraint is applied to adjacent sections. The constraint condition is that the dielectric constant of the end point of the previous section is equal to the dielectric constant of the starting point of the next section. The linear dielectric constant distributions of each section are then spliced ​​together to obtain the dielectric constant distribution of each cable segment along the entire line.

[0073] In another alternative implementation, in step B3, the dielectric constant distribution of each cable segment can also be inverted by: Empirical Mode Decomposition (EMD) was performed on the traveling wave current waveform used to extract the time difference of arrival (TDOA). EMD decomposes the original waveform into several intrinsic mode functions (IMFs). The three IMFs with the highest energy were selected and superimposed for reconstruction. The energy was calculated as the sum of the squares of the amplitudes at each sampling point of the IMF. The reconstructed waveform removed high-frequency noise and low-frequency drift.

[0074] The instantaneous amplitude envelope is extracted from the reconstructed waveform. The extraction method involves constructing an analytic signal, where the real part of the analytic signal represents the reconstructed waveform, and the imaginary part represents the Hilbert transform of the reconstructed waveform. The magnitude of the analytic signal is calculated as the instantaneous amplitude envelope. The arrival time of the traveling wave is re-identified on the instantaneous amplitude envelope by finding the moment when the envelope amplitude first exceeds three times the root mean square value of the waveform's first 100 sampling points. The arrival time difference of the traveling wave between adjacent measurement points is re-extracted and used for subsequent inversion.

[0075] Path correction is performed on the cable segment lengths between adjacent measuring points. The turning angles and elevation information of each laying path are extracted from the cable construction archive. For cable segments with turning angles, the arc length is calculated based on the turning angle and the radius of curvature at the turning angle; the arc length is calculated by multiplying the radius of curvature by the turning angle in radians. For cable segments with elevation changes, the oblique length is calculated based on the horizontal distance and the elevation difference; the oblique length is calculated by taking the square root of the square of the horizontal distance plus the square of the elevation difference. A path correction coefficient is introduced, which is the ratio of the actual calculated length to the length marked in the construction archive. Step B2 is then re-executed using the corrected length to calculate the equivalent traveling wave propagation velocity.

[0076] A state-space model is established to invert the dielectric constant of each segment. The dielectric constant of each segment is treated as a state variable. The state equation describes the current segment's dielectric constant as equal to the previous segment's dielectric constant plus process noise, where the process noise follows a normal distribution with a mean of 0. The observation equation is the established correlation equation between the dielectric constant of each segment and the time difference between measurement points, where the observation noise follows a normal distribution with a mean of 0.

[0077] Kalman filtering is used for sequential estimation. Starting from the first segment of the line, the dielectric constant estimate of the first segment is initialized using the time difference between the first measurement points and the first measurement point interval. The initial estimate is set to 2.3. Segments are then moved towards the end of the line, and the dielectric constant estimate of the current segment is updated each time using the time difference between the new measurement point intervals. The update includes a prediction step and a correction step. The prediction step uses the state equation to predict the dielectric constant of the current segment, and the correction step uses the observation equation and Kalman gain to correct the predicted value. The Kalman gain is calculated based on the prediction error and the observation error, and outputs the dielectric constant distribution of each segment.

[0078] In this embodiment of the application, in step B6, the distribution of the dielectric loss factor of each cable segment is inverted by: based on the theory of electromagnetic wave propagation in a lossy medium, the attenuation coefficient... With loss factor satisfy: in The attenuation coefficient is... For frequency, The relative permittivity, At the speed of light, For loss factor, Pi is the mathematical constant of a circle.

[0079] Traveling wave through length Energy attenuation after the cable section ,in In order to output energy, To input energy, The base of the natural logarithm, This refers to the length of the cable segment.

[0080] measuring point With measuring points Between contains the first Section of cable, among which Number the measurement points. 1) +1 represents the starting cable segment number. The attenuation ratio calculated in step B5 is: in The energy attenuation ratio between measurement points. For measuring points Energy in the preset frequency band For measuring points Energy in the preset frequency band For the first Segment attenuation coefficient, For the first Segment length.

[0081] The logarithmic decay is: in The logarithmic decay, This represents the logarithm to base 10, with 8.686 being the neper to decibel conversion factor.

[0082] Select the center frequency of the preset frequency band from 100kHz to 500kHz in step B5. Substituting the characteristic frequency into the attenuation coefficient formula: Define coefficients ,in For the first Segment coefficient, The first step obtained by inversion in step B3 The dielectric constant of the segment. The equation simplifies to: Define loss factor vector Logarithmic decay vector Establish a system of equations ,in The coefficient matrix, This represents the total number of cable segments. The total number of measurement points. This indicates transpose.

[0083] Construct the regularization objective function: Constraints ,in Let be the objective function. It is the square of the 2-norm. It is a second-order difference matrix. The smoothing parameters are solved using the active set algorithm, and are initialized... Iterate until the KKT conditions are met. Smooth the logarithmic decay in step B5 using a moving average: Boundary processing The loss factor for each segment is obtained by using the smoothed data. .

[0084] In an optional implementation, in step B6, the dielectric loss factor distribution of each cable segment can be inverted by: based on the attenuation ratio, and through the attenuation law of electromagnetic waves in the loss medium, inverting the dielectric loss factor distribution of each cable segment.

[0085] The preset frequency band is divided into several sub-bands. The energy in each sub-band is calculated by summing the squares of the amplitudes at each frequency point of the traveling wave spectrum within the sub-band and multiplying by the frequency resolution. The energy attenuation ratio between adjacent measurement points in each sub-band is calculated by dividing the energy of the sub-band at the previous measurement point by the energy of the corresponding sub-band at the next measurement point.

[0086] Attenuation equations are established for each sub-frequency band. For each sub-frequency band, the center frequency is selected as the characteristic frequency, and the coefficient is defined as 8.686 multiplied by pi, the center frequency, the square root of the dielectric constant, divided by the speed of light, and then multiplied by the cable segment length. The attenuation equation is that the logarithmic attenuation of the measurement point interval is equal to the sum of the products of the coefficients of the three cable segments contained in that interval and the loss factor. A system of equations is established for all measurement point intervals and all sub-frequency bands along the entire line; the total number of equations is the number of measurement point intervals multiplied by the number of sub-frequency bands.

[0087] The weighted least squares method is used to solve the problem. Different weights are assigned to the equations for different sub-frequency bands, with each weight being the center frequency of each sub-frequency band divided by the sum of the center frequencies of all sub-frequency bands. A weighted sum of squared residuals is constructed, where the residuals are the differences between the calculated and measured values ​​of each equation. The partial derivative of the loss factor vector is taken and set to zero, and the linear equations are solved to obtain the loss factor distribution for each cable segment.

[0088] In another optional implementation, in step B6, the dielectric loss factor distribution of each cable segment can also be inverted by: based on the attenuation ratio, through the attenuation law of electromagnetic waves in the loss medium, inverting the dielectric loss factor distribution of each cable segment.

[0089] A frequency-dependent model of the loss factor is established. The loss factor of each cable segment is expressed as a second-order polynomial function of the frequency, with the function form being: loss factor equals zero-order coefficient plus first-order coefficient multiplied by frequency plus second-order coefficient multiplied by frequency squared. Each cable segment has three polynomial coefficients as parameters to be determined.

[0090] Utilizing energy attenuation information from multiple discrete frequency points within a preset frequency band, several frequency points are uniformly selected within the preset frequency band. For each frequency point, the energy of the narrowband spectrum near that frequency is calculated. The narrowband spectrum energy is the sum of the squares of the amplitudes of several frequency points before and after that frequency point multiplied by the frequency resolution. The energy attenuation ratio between adjacent measurement points at each frequency point is calculated.

[0091] An attenuation equation is established for each frequency point. The loss factor in the equation is expressed as the frequency of that frequency point, substituted into a second-order polynomial. The coefficient remains 8.686 multiplied by pi, multiplied by the frequency, multiplied by the square root of the dielectric constant, divided by the speed of light, and then multiplied by the cable segment length. A system of equations is established for all frequency points and all measurement point intervals. The number of equations is the number of frequency points multiplied by the number of measurement point intervals, and the unknowns are the coefficients of the three polynomials for each cable segment.

[0092] The nonlinear least squares method is used for solution. The zero-order coefficients of each segment are initialized to the typical loss factor values ​​of the new cable, while the first- and second-order coefficients are initialized to zero. A residual vector is constructed, and the partial derivatives of the residuals with respect to each coefficient are calculated to form a Jacobian matrix. The coefficients are iteratively updated using the Gauss-Newton method, with the update formula being the current coefficient value minus the transpose of the Jacobian matrix multiplied by the inverse of the Jacobian matrix, then multiplied by the product of the transpose of the Jacobian matrix and the residual vector. The iteration terminates when the relative change in the coefficients is less than a set threshold, yielding the polynomial coefficients of the loss factor for each segment.

[0093] Step 3: Using the dielectric constant and dielectric loss factor of each cable segment as two-dimensional feature vectors, and through coupling analysis of the degree of anomaly in the dielectric constant and the degree of anomaly in the dielectric loss factor, the insulation degradation index of each cable segment is calculated, including the following steps C1-C5: C1: Based on the dielectric constant distribution and the dielectric loss factor distribution, an insulation health evolution baseline is constructed in a two-dimensional feature space. The insulation health evolution baseline adopts a function curve describing the nonlinear relationship between the dielectric constant and the dielectric loss factor. C2: For any cable segment, the actual state point of the segment is determined in the two-dimensional feature space using the dielectric constant value corresponding to the dielectric constant distribution of the segment and the dielectric loss factor value corresponding to the dielectric loss factor distribution of the segment as coordinate components. C3: Calculate the vertical deviation distance between the actual state point and the insulation health evolution baseline. The vertical deviation distance is the absolute value of the difference between the coordinate value of the actual state point in the dielectric loss factor dimension and the dielectric loss factor value of the insulation health evolution baseline at the same dielectric constant value. C4: Calculate the degradation risk amplification factor based on the coordinates of the actual state point in the dielectric constant dimension; C5: Multiply the vertical deviation distance by the degradation risk amplification factor to obtain the insulation degradation index of the cable segment.

[0094] In this embodiment of the application, in step 3, the coupling analysis is performed by: calculating the insulation degradation index of each cable segment by analyzing the degree of abnormality of the dielectric constant and the degree of abnormality of the dielectric loss factor.

[0095] Based on the dielectric constant distribution and dielectric loss factor distribution of all cable segments obtained through inversion, an insulation health evolution baseline is constructed in a two-dimensional feature space. The baseline adopts a power function form. ,in The dielectric loss factor on the baseline. Where is the dielectric constant. and These are parameters to be determined. The nominal dielectric constant of the new cable is determined. The parameters are determined by fitting data points from all cable segments using the least squares method. and .

[0096] Regarding the first The actual state point coordinates of the cable segment are: Calculate the vertical deviation distance. Calculate the degradation risk amplification factor ,in The dielectric constant degradation interval is set to 1.2 times the nominal value of the new cable.

[0097] Insulation degradation index is .

[0098] In an optional implementation, in step 3, the coupling analysis can be performed by: By coupling the anomalies in dielectric constant and dielectric loss factor, the insulation degradation index of each cable segment is calculated. Based on the dielectric constant and dielectric loss factor data of all cable segments, an insulation health evolution baseline is constructed in a two-dimensional feature space. The baseline adopts an exponential function form. ,in and The parameters are to be determined and are fitted using the least squares method.

[0099] Regarding the first The actual coordinates of the cable segment are: Calculate the vertical deviation of this point from the baseline, i.e., the deviation in the dimension of the dielectric loss factor. .

[0100] Calculate the degradation risk amplification factor. The amplification factor reflects the contribution of the degree of deviation of the dielectric constant to the overall degradation risk, and is calculated using a linear function. ,in The basic weight coefficient is taken as: The gain coefficient is determined based on historical degradation data.

[0101] The insulation degradation index is the product of the vertical deviation distance and the degradation risk amplification factor. .

[0102] In another alternative implementation, in step 3, the coupling analysis can also be performed by: The insulation degradation index of each cable segment was calculated by coupling the anomalies in dielectric constant and dielectric loss factor. An insulation health evolution baseline was constructed in a two-dimensional feature space based on data from all cable segments. A piecewise linear function was used to describe the baseline, dividing the dielectric constant range into several intervals, with the baseline within each interval being a linear function. The interval division was determined based on the data distribution density, and data points were grouped using cluster analysis. Linear regression was then used to fit the baseline segment for each interval's data points.

[0103] Regarding the first Determine the dielectric constant of a section of cable. Within the specified interval, find the dielectric constant on the baseline segment of that interval. The corresponding reference loss factor value Calculate the vertical deviation distance. .

[0104] Calculate the degradation risk amplification factor. A piecewise function is used. When the dielectric constant is less than or equal to 1.1 times the nominal value of the new cable, the amplification factor is 1. When the dielectric constant is greater than 1.1 times but less than or equal to 1.2 times, the amplification factor increases linearly to 2. When the dielectric constant is greater than 1.2 times, the amplification factor is 3.

[0105] Insulation degradation index is .

[0106] It should be noted that in the two-dimensional feature space, the dielectric constant dimension refers to the dimension constructed with the dielectric constant as the coordinate axis. This space consists of two coordinate axes: the horizontal axis represents the dielectric constant dimension, and the vertical axis represents the dielectric loss factor dimension. Each cable segment corresponds to a point with coordinates as follows: .

[0107] The coordinate values ​​of the dielectric constant dimension are the dielectric constant values ​​for that segment. When calculating the vertical deviation distance, the coordinate values ​​of the dielectric constant dimension are fixed, and only the differences in the dielectric loss factor dimension are compared. When calculating the degradation risk amplification factor, the amplification factor is determined based on the coordinate values ​​of the dielectric constant dimension; a larger dielectric constant value indicates a higher degree of degradation, and the corresponding amplification factor is larger.

[0108] Step 4: Based on the numerical distribution of the insulation degradation index, each cable segment is divided into high-risk degradation segment, medium-risk degradation segment, and low-risk degradation segment, including the following steps D1-D6: D1: Based on the numerical similarity of the insulation degradation index of each cable segment, cable segments with similar insulation degradation indices are aggregated into multiple cable segment groups; D2: Calculate the arithmetic mean of the insulation degradation index of each cable segment within the cable segment group, and use it as the group degradation index of the cable segment group; D3: Based on the numerical range of the group deterioration index, a preliminary risk level determination is made for the cable segment group to obtain a preliminary risk level; D4: Extract the vertical deviation distance of each cable segment in the cable segment group during the calculation of the insulation degradation index, and calculate the maximum value of the vertical deviation distance in the cable segment group; D5: When the maximum value of the vertical deviation distance exceeds the preset abnormal deviation threshold, the preliminary risk level is increased by one level to obtain the final risk level; D6: Assign the final risk level to each cable segment within the cable segment group.

[0109] Furthermore, based on the numerical similarity of the insulation degradation index of each cable segment, cable segments with similar insulation degradation indices are aggregated into multiple cable segment groups. According to the spatial order of the current collector cable line, a continuous degradation region is identified in which the insulation degradation index of N or more consecutive cable segments exceeds a preset degradation identification threshold. For each of the continuous deterioration areas, the cable segment with the largest insulation deterioration index within the continuous deterioration area is identified as a suspected deterioration source segment; Centered on the suspected deterioration source segment, the judgment is extended to the adjacent cable segments in front and behind. When the insulation deterioration index of the adjacent cable segment is greater than the deterioration identification threshold, or when the difference in the insulation deterioration index between the adjacent cable segment and the suspected deterioration source segment is less than the preset gradient threshold, the adjacent cable segment is included in the continuous deterioration area. Repeat the extended determination until neither of the adjacent cable segments at the two ends of the continuously deteriorated area meets the inclusion condition, and then aggregate all the cable segments in the continuously deteriorated area into a cable segment group. For the remaining cable segments that are not included in any of the continuous degradation regions, the coordinate values ​​of the actual state points of the remaining cable segments in the dielectric constant dimension during the calculation of the insulation degradation index are extracted. The remaining cable segments are divided into corresponding degradation stages according to the coordinate values. The remaining cable segments that belong to the same degradation stage and whose insulation degradation indices differ by less than a preset threshold are aggregated into a cable segment group.

[0110] Step 5: Within the high-risk degradation range, the coordinates of the fault breakdown point are determined based on the location where the polarity of the traveling wave current waveform reverses, including the following steps E1-E6: E1: Based on the dielectric constant distribution of each cable segment, calculate the traveling wave propagation velocity of each cable segment and establish a segmented wave velocity model of the current collector cable line; E2: Detect the polarity reversal feature of the traveling wave current waveform and extract the measured propagation time of the traveling wave from the fault point to the monitoring endpoint; E3: For each of the high-risk deterioration segments, the location with the largest insulation deterioration index within that segment is taken as the initial candidate point of the fault. Based on the segmented wave velocity model, the theoretical propagation time of the traveling wave from the initial candidate point of the fault to the monitoring endpoint is calculated. E4: Calculate the time error between the theoretical propagation time and the measured propagation time. When the time error is greater than the preset time tolerance, adjust the position of the initial candidate point of the fault along the spatial direction of the high-risk deterioration segment according to the positive or negative sign of the time error to obtain the updated candidate point position. E5: Based on the updated candidate point position, repeat the steps of calculating the theoretical propagation time and adjusting the candidate point position until the time error is less than or equal to the time tolerance, and use the candidate point position at this time as the coordinates of the fault breakdown point. E6: When there are multiple high-risk deterioration segments, the iterative positioning process is performed for each high-risk deterioration segment, and the candidate point with the smallest final time error is selected as the coordinate of the fault breakdown point.

[0111] Step 6: Mark the remaining locations in the high-risk deterioration section, except for the location of the fault breakdown point, as first-level insulation hazard points, and mark the medium-risk deterioration section as a second-level insulation hazard area.

[0112] Example 3 is an embodiment of the present invention. This embodiment provides a fault location and hidden danger identification system for a collector cable line, including: a data acquisition module, used to set up multiple measuring points on the collector cable line to collect fault traveling wave signals and obtain the traveling wave current waveform of each measuring point; The feature analysis module is used to obtain the dielectric parameter distribution of each cable segment by analyzing the propagation characteristics of the traveling wave current waveform at different measurement points. The dielectric parameter distribution includes the dielectric constant distribution and the dielectric loss factor distribution. The coupling analysis module is used to take the dielectric constant and dielectric loss factor of each cable segment as two-dimensional feature vectors, and calculate the insulation degradation index of each cable segment by coupling analysis of the degree of abnormality of the dielectric constant and the degree of abnormality of the dielectric loss factor. The degradation analysis module is used to divide each cable segment into high-risk degradation segment, medium-risk degradation segment, and low-risk degradation segment according to the numerical distribution of the insulation degradation index. The fault location module is used to determine the coordinates of the fault breakdown point based on the location where the polarity of the traveling wave current waveform reverses within the high-risk deterioration section. The hazard analysis module is used to mark the remaining locations in the high-risk deterioration section, excluding the location of the fault breakdown point, as first-level insulation hazard points, and to mark the medium-risk deterioration section as second-level insulation hazard areas.

[0113] This embodiment also provides an electronic device applicable to a method for locating faults and identifying potential hazards in a power collection cable line, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the method for locating faults and identifying potential hazards in a power collection cable line as proposed in the above embodiment.

[0114] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements a method for locating faults and identifying potential hazards in a current collector cable line as proposed in the above embodiment.

[0115] The storage medium proposed in this embodiment and the method for locating faults and identifying potential hazards in a current collector cable line proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0116] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0117] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for fault location and hidden danger identification in a current collector cable line, characterized in that: include, Multiple measuring points are set up on the collector cable line to collect fault traveling wave signals and obtain the traveling wave current waveform at each measuring point. By analyzing the propagation characteristics of the traveling wave current waveform at different measurement points, the dielectric parameter distribution of each cable segment is obtained. The dielectric parameter distribution includes the dielectric constant distribution and the dielectric loss factor distribution. The dielectric constant and dielectric loss factor of each cable segment are used as two-dimensional feature vectors. By coupling analysis of the degree of abnormality of the dielectric constant and the degree of abnormality of the dielectric loss factor, the insulation degradation index of each cable segment is calculated. Based on the numerical distribution of the insulation degradation index, each cable segment is divided into high-risk degradation segment, medium-risk degradation segment, and low-risk degradation segment. Within the high-risk degradation range, the coordinates of the fault breakdown point are determined based on the location where the polarity of the traveling wave current waveform reverses. The locations in the high-risk deterioration section, excluding the location of the fault breakdown point, are marked as first-level insulation hazard points, and the medium-risk deterioration section is marked as a second-level insulation hazard area.

2. The method for fault location and hidden danger identification of a current collector cable line as described in claim 1, characterized in that: The step of obtaining the distribution of dielectric parameters of each cable segment by analyzing the propagation characteristics of the traveling wave current waveform at different measuring points includes performing time-domain analysis on the traveling wave current waveform and extracting the travel wave arrival time difference between adjacent measuring points. Based on the travel wave arrival time difference and the cable segment length between adjacent measuring points, the equivalent travel wave propagation speed of each cable segment is calculated. Based on the equivalent traveling wave propagation speed, the dielectric constant distribution of each cable segment is inverted through the physical relationship between electromagnetic wave propagation speed and dielectric constant.

3. The method for fault location and hidden danger identification of a current collector cable line as described in claim 2, characterized in that: The step of obtaining the distribution of dielectric parameters of each cable segment by analyzing the propagation characteristics of the traveling wave current waveform at different measuring points also includes performing frequency domain transformation on the traveling wave current waveform to obtain the traveling wave spectrum at each measuring point. Extract the energy of the preset frequency band in the traveling wave spectrum and calculate the attenuation ratio of the preset frequency band energy between adjacent measurement points; Based on the attenuation ratio, the distribution of the dielectric loss factor of each cable segment is inverted by using the attenuation law of electromagnetic waves in the loss medium.

4. The method for fault location and hidden danger identification of a current collector cable line as described in claim 3, characterized in that: The calculation of the insulation degradation index of each cable segment includes constructing an insulation health evolution baseline in a two-dimensional feature space based on the dielectric constant distribution and the dielectric loss factor distribution. For any cable segment, the actual state point of the segment is determined in the two-dimensional feature space using the dielectric constant value corresponding to the dielectric constant distribution and the dielectric loss factor value corresponding to the dielectric loss factor distribution of the segment as coordinate components. Calculate the vertical deviation distance between the actual state point and the insulation health evolution baseline; Calculate the degradation risk amplification factor based on the coordinates of the actual state point in the dielectric constant dimension; Multiplying the vertical deviation distance by the degradation risk amplification factor yields the insulation degradation index of the cable segment.

5. The method for fault location and hidden danger identification of a current collector cable line as described in claim 4, characterized in that: The step of dividing each cable segment into high-risk deterioration segments, medium-risk deterioration segments, and low-risk deterioration segments according to the numerical distribution of the insulation deterioration index includes, based on the numerical similarity of the insulation deterioration index of each cable segment, aggregating cable segments with similar insulation deterioration indices into multiple cable segment groups. Calculate the arithmetic mean of the insulation degradation index of each cable segment within the cable segment group, and use it as the group degradation index of the cable segment group; Based on the numerical range of the group deterioration index, a preliminary risk level is determined for the cable segment group to obtain a preliminary risk level. Extract the vertical deviation distance of each cable segment within the cable segment group during the calculation of the insulation degradation index, and calculate the maximum value of the vertical deviation distance within the cable segment group; When the maximum value of the vertical deviation distance exceeds the preset abnormal deviation threshold, the preliminary risk level is increased by one level to obtain the final risk level; The final risk level is assigned to each cable segment within the cable segment group.

6. The method for fault location and hidden danger identification of a current collector cable line as described in claim 5, characterized in that: Based on the numerical similarity of the insulation degradation index of each cable segment, cable segments with similar insulation degradation indices are aggregated into multiple cable segment groups. According to the spatial order of the current collector cable line, a continuous degradation region is identified in which the insulation degradation index of N or more consecutive cable segments exceeds a preset degradation identification threshold. For each of the continuous deterioration areas, the cable segment with the largest insulation deterioration index within the continuous deterioration area is identified as a suspected deterioration source segment; Centered on the suspected deterioration source segment, the judgment is extended to the adjacent cable segments in front and behind. When the insulation deterioration index of the adjacent cable segment is greater than the deterioration identification threshold, or when the difference in the insulation deterioration index between the adjacent cable segment and the suspected deterioration source segment is less than the preset gradient threshold, the adjacent cable segment is included in the continuous deterioration area. Repeat the extended determination until neither of the adjacent cable segments at the two ends of the continuously deteriorated area meets the inclusion condition, and then aggregate all the cable segments in the continuously deteriorated area into a cable segment group. For the remaining cable segments that are not included in any of the continuous degradation regions, the coordinate values ​​of the actual state points of the remaining cable segments in the dielectric constant dimension during the calculation of the insulation degradation index are extracted. The remaining cable segments are divided into corresponding degradation stages according to the coordinate values. The remaining cable segments that belong to the same degradation stage and whose insulation degradation indices differ by less than a preset threshold are aggregated into a cable segment group.

7. The method for fault location and hidden danger identification of a current collector cable line as described in claim 6, characterized in that: The step of determining the fault breakdown point coordinates based on the location where the polarity of the traveling wave current waveform reverses includes calculating the traveling wave propagation velocity of each cable segment based on the dielectric constant distribution of each cable segment, and establishing a segmented wave velocity model of the current collector cable line. The polarity reversal feature of the traveling wave current waveform is detected, and the measured propagation time of the traveling wave from the fault point to the monitoring endpoint is extracted; For each high-risk deterioration segment, the location with the largest insulation deterioration index within that segment is taken as the initial candidate point of the fault. Based on the segmented wave velocity model, the theoretical propagation time of the traveling wave from the initial candidate point of the fault to the monitoring endpoint is calculated. Calculate the time error between the theoretical propagation time and the measured propagation time. When the time error is greater than the preset time tolerance, adjust the position of the initial candidate point of the fault along the spatial direction of the high-risk deterioration segment according to the positive or negative sign of the time error to obtain the updated candidate point position. Based on the updated candidate point position, repeat the steps of calculating the theoretical propagation time and adjusting the candidate point position until the time error is less than or equal to the time tolerance, and use the candidate point position at this time as the coordinates of the fault breakdown point. When there are multiple high-risk deterioration segments, the iterative localization process is performed for each high-risk deterioration segment, and the candidate point with the smallest final time error is selected as the coordinate of the fault breakdown point.

8. A fault location and hazard identification system for a current collector cable line, employing the fault location and hazard identification method for a current collector cable line as described in any one of claims 1 to 7, characterized in that, include: The data acquisition module is used to set up multiple measuring points on the collector cable line to collect fault traveling wave signals and obtain the traveling wave current waveform at each measuring point; The feature analysis module is used to obtain the dielectric parameter distribution of each cable segment by analyzing the propagation characteristics of the traveling wave current waveform at different measurement points. The dielectric parameter distribution includes the dielectric constant distribution and the dielectric loss factor distribution. The coupling analysis module is used to take the dielectric constant and dielectric loss factor of each cable segment as two-dimensional feature vectors, and calculate the insulation degradation index of each cable segment by coupling analysis of the degree of abnormality of the dielectric constant and the degree of abnormality of the dielectric loss factor. The degradation analysis module is used to divide each cable segment into high-risk degradation segment, medium-risk degradation segment, and low-risk degradation segment according to the numerical distribution of the insulation degradation index. The fault location module is used to determine the coordinates of the fault breakdown point based on the location where the polarity of the traveling wave current waveform reverses within the high-risk deterioration section. The hazard analysis module is used to mark the remaining locations in the high-risk deterioration section, excluding the location of the fault breakdown point, as first-level insulation hazard points, and to mark the medium-risk deterioration section as second-level insulation hazard areas.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method for fault location and hidden danger identification of a current collector cable line according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for fault location and hidden danger identification of a current collector cable line as described in any one of claims 1 to 7.

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