Cable fault early warning method and system, storage medium and program product

Abstract

The invention provides a cable fault early warning method and system, a storage medium and a program product, and relates to the technical field of electrical variable measurement. And calculating the absolute value of the amplitude difference under adjacent sampling points, comparing the absolute value with the relative change value, and screening out signal parts which are really changed and possibly predict faults. Waveform segments in a preset time window before and after the traveling wave starting point are extracted to generate a front-end feature segment and a rear-end feature segment; carrying out discretization, Fourier transform and other operations on the characteristic fragments, converting a complex waveform of a time domain into a frequency domain for analysis, calculating time delay by searching a peak position in a time domain cross-correlation function sequence through correlation calculation of the frequency domain, and comparing with a traveling wave theoretical propagation time difference calculated by detecting the length of a cable between groups; if the difference value is greater than the threshold value, the fault hidden danger is judged and early warning is triggered, the cable section with the fault hidden danger is positioned, the fault repair efficiency is improved, and the normal power supply order and the normal operation of the power utilization unit are ensured.

Description

Technical Field

[0001] The present application relates to the technical field of measuring electrical variables, and in particular to a cable fault early warning method, system, storage medium, and program product. Background Art

[0002] In the rapid development of today's society, the application scale of high-voltage cables in power transmission systems continues to expand. It has become a core element to ensure urban power supply and electricity consumption of many key infrastructures, and its importance is becoming increasingly prominent.

[0003] At present, the common practice for cable fault-related problems is to rely on some basic electrical detection tools to test the cables during a power outage. By detecting basic electrical parameters such as resistance and current and comparing them with the normal parameter range, it is hoped that faults can be discovered in time and corresponding measures can be taken to ensure the normal operation of the cable.

[0004] In actual cable fault troubleshooting scenarios, since it can only know that there is a fault in the cable but cannot accurately point out the specific location of the fault, the fault repair efficiency is low, affecting the normal power supply order and the normal operation of the power user. Summary of the Invention

[0005] The present application provides a cable fault early warning method, system, storage medium and program product for improving fault repair efficiency, ensuring normal power supply order and normal operation of power users.

[0006] In the first aspect, the present application provides a cable fault warning method, including: selecting adjacent monitoring terminals as a detection group; setting the monitoring terminals at both ends of the cable line, at intervals, at the junctions between cables, and at the junctions between cables and overhead sections; determining the traveling wave current signal collected by the detection group according to the direction of the current, and determining the traveling wave current signal collected by the upstream monitoring terminal as the front-end traveling wave signal, and the traveling wave current signal collected by the downstream monitoring terminal as the rear-end traveling wave signal; calculating the absolute value of the amplitude difference between the traveling wave current signal of the latter sampling point and the previous sampling point at adjacent sampling points; comparing the absolute value with the relative change value, the relative change value is the amplitude of the traveling wave current signal of the previous sampling point multiplied by a preset frequency threshold; when only the absolute value of the rear-end traveling wave signal is greater than the corresponding relative change value In the case of a changing value; waveform segments within a preset time window before and after the starting point of the traveling wave are extracted from the front-end traveling wave signal and the rear-end traveling wave signal respectively to generate front-end characteristic segments and rear-end characteristic segments; the front-end characteristic segments and the rear-end characteristic segments are discretized respectively to obtain a front-end discrete sequence and a rear-end discrete sequence; and Fourier transform is performed to obtain a front-end discrete frequency domain and a rear-end discrete frequency domain; the product of the conjugate of the front-end discrete frequency domain and the rear-end discrete frequency domain is calculated, and a time domain cross-correlation function sequence is obtained by inverse Fourier transform; the peak position in the time domain cross-correlation function sequence is searched and the time delay is calculated; the theoretical propagation time difference of the traveling wave is calculated according to the cable length between the detection groups; if the difference between the time delay and the theoretical propagation time difference of the traveling wave is greater than the threshold, it is determined that there is a potential fault in the cable section covered by the detection group and an early warning is triggered.

[0007] By implementing the above technical solution, monitoring terminals are installed at both ends of the cable line, at intervals, at cable-to-cable junctions, and at the junctions between cables and overhead sections. This layout enables the collection of traveling wave current signals from multiple key locations. The traveling wave current signals collected by the detection group are then divided into front-end and back-end traveling wave signals based on current direction, facilitating subsequent differentiated analysis. The absolute value of the amplitude difference is calculated at adjacent sampling points and compared with the relative change value (calculated by multiplying the amplitude of the traveling wave current signal at the previous sampling point by a preset frequency threshold). This filter identifies signal portions that have genuine changes and may indicate a fault, avoiding misinterpreting normal fluctuations as fault signals. Then, if only the absolute value of the back-end traveling wave signal is greater than the corresponding relative change value, a fault is likely present, and the fault is likely to occur within the cable section covered by the detection group. Waveform segments within a preset time window before and after the starting point of the traveling wave are extracted to generate front-end and back-end feature segments, focusing on key waveform features and removing irrelevant interference information. These characteristic segments are discretized and Fourier transformed, and the complex waveforms in the time domain are converted into the frequency domain for analysis. Through relevant calculations in the frequency domain (such as calculating the product of the front-end discrete frequency domain and the conjugate of the back-end discrete frequency domain and obtaining the time domain cross-correlation function sequence through inverse Fourier transform), the time delay is calculated by searching for the peak position in the time domain cross-correlation function sequence, and then compared with the theoretical propagation time difference of the traveling wave calculated by combining the cable length between the detection groups. If the difference is greater than the threshold, the fault is determined to be a hidden danger and an early warning is triggered. The cable section with the fault risk is located, the fault repair efficiency is improved, and the normal power supply order and the normal operation of the power user are guaranteed.

[0008] In combination with some embodiments of the first aspect, in some embodiments, after the step of comparing the absolute value with the relative change value, where the relative change value is the amplitude of the traveling wave current signal at the previous sampling point multiplied by a preset frequency threshold, the method further includes: determining whether there is a connection point between the cables before the detection group; if not, executing the steps when only the absolute value of the rear-end traveling wave signal is greater than the corresponding relative change value; if so, determining all cables connected to the connection point between the cables, and then searching for the defined monitoring terminal closest to the connection point between the cables from all cables; calculating the change in the amplitude of the traveling wave current flowing into the cable where the detection group is located based on the impedance of the monitoring terminal to obtain an initial compensation value; determining the front-end compensation value of the front-end traveling wave signal based on the cable length from the connection point between the cables to the upstream monitoring terminal and the initial compensation value; determining the rear-end compensation value of the rear-end traveling wave signal based on the cable length from the connection point between the cables to the downstream monitoring terminal and the initial compensation value; using the front-end compensation value to compensate for the relative change value corresponding to the front-end traveling wave signal, and using the rear-end compensation value to compensate for the relative change value corresponding to the rear-end traveling wave signal; and executing the steps when only the absolute value of the rear-end traveling wave signal is greater than the corresponding relative change value.

[0009] By adopting the above technical solution, in view of the possible branch structure of the T-type cable, an additional step is added to determine whether there is a connection point between the cables before the detection group (the connection point here includes the T-type branch point). If not, continue the subsequent judgment according to the normal process; if it exists, start a series of targeted compensation operations. First, determine all the cables connected to the connection point (such as the T-type branch point), and then search for the monitoring terminal closest to the connection point from all the cables, and lock the monitoring equipment of each branch and related position that will affect the current detection group signal. Then, based on the impedance of the monitoring terminal, the change in the amplitude of the traveling wave current flowing into the cable where the detection group is located is calculated to obtain the initial compensation value. This initial compensation value can quantify the current change caused by factors such as the difference in branch loads at the T-type branch, and accurately reflect the degree of influence of the branch current on the current amplitude of the main or branch line where the detection group is located. Then, the front-end compensation value of the front-end traveling wave signal and the rear-end compensation value of the rear-end traveling wave signal are determined respectively based on the cable length from the connection point between the cables (such as the T-type branch point) to the upstream monitoring terminal and the downstream monitoring terminal, taking into account the changes in the branch current during the cable transmission process at different positions and the impact on the front-end and rear-end traveling wave signals. Finally, these compensation values ​​are used to compensate the corresponding relative change values ​​before executing the subsequent judgment steps. Through this compensation process that fits the actual situation of the T-type cable branch structure, the interference factors caused by the change of the branch current can be effectively eliminated, so that the subsequent judgment of whether the front-end and rear-end traveling wave signals are abnormal is more in line with the actual cable operation status, especially when the branch current fluctuates greatly, avoiding its normal fluctuation from being misjudged as a fault signal, and preventing early fault signals from being masked and missed, thereby improving the accuracy of fault warning judgment in T-type cable application scenarios.

[0010] In conjunction with some embodiments of the first aspect, in some embodiments, the step of calculating the change in the amplitude of the traveling wave current flowing into the cable where the detection group is located to obtain the initial compensation value based on the impedance of the monitoring terminal specifically includes: determining the assigned defined monitoring terminal as the first monitoring terminal based on the distribution relationship of the traveling wave; determining the assigned defined monitoring terminal in the same cable as the detection group as the second monitoring terminal, and determining another assigned defined monitoring terminal as the third monitoring terminal; determining the initial compensation value according to the initial compensation value calculation function; the initial compensation value calculation function is: Where, is the equivalent wave impedance at the connection point between cables; is the transmission coefficient of the cable between the first monitoring terminal and the connection point between the cables; is the current value of the cable between the first monitoring terminal and the connection point between the cables; is the theoretical current value of the cable between the second monitoring terminal and the connection point between the cables, is the initial compensation value.

[0011] By employing the above technical solution, when calculating the change in the amplitude of the traveling wave current flowing into the cable where the detection group is located to obtain the initial compensation value, the first, second, and third monitoring terminals are determined based on the traveling wave distribution relationship. This step clarifies the role of each monitoring terminal in the traveling wave current distribution, laying the foundation for subsequent accurate calculations. Based on the wave impedance of each branch, a specific formula is used to calculate the compensation value for each transmission branch. Wave impedance reflects the electrical characteristics of the branch. Different wave impedances of different branches can cause changes in the traveling wave current, such as shunting, at the branch. Using this formula to calculate the compensation value, it is possible to accurately quantify the current changes caused by these branch characteristics. In a T-type cable branch structure, differences in branch loads can lead to complex variations in current magnitude and phase. By accurately calculating the transmission branch compensation value, the impact of branch current variations on the traveling wave current signal amplitude of the cable where the detection group is located can be effectively compensated. This prevents normal branch current fluctuations from being misidentified as fault signals, or early fault signals from being masked and missed. This improves the accuracy and effectiveness of fault feature extraction for T-type cables and enhances the reliability and accuracy of the entire cable fault warning system.

[0012] In conjunction with some embodiments of the first aspect, in some embodiments, the step of determining the front-end compensation value of the front-end traveling wave signal based on the cable length from the connection point between the cables to the upstream monitoring terminal and the initial compensation value specifically includes: calculating the front-end compensation value based on an attenuation function; the attenuation function is: Where, is the compensation value, is the amplitude after reverse attenuation, is the original amplitude, is the cable attenuation constant, is the cable length, is the initial compensation value.

[0013] By adopting the above technical solution, when determining the front-end compensation value of the front-end traveling wave signal, the amplitude measured by the monitoring terminal is first subjected to reverse attenuation processing to calculate the amplitude just after leaving the T-type branch point, and then the current amplitude change caused by factors such as traveling wave distribution at the T-type branch point is added to obtain the original amplitude. Finally, the final compensation value is determined by calculating the difference between the original amplitude and the amplitude measured by the monitoring terminal. In the T-type cable branch structure, the transmission of the traveling wave current signal is affected by both the branch characteristics and the cable attenuation. Through the above steps, the amplitude of the front-end traveling wave signal is compensated, and the amplitude deviation caused by the branch current change and the cable attenuation is effectively eliminated, so that the front-end traveling wave signal can truly reflect the actual operating status of the cable, avoiding fault misjudgment and missed judgment due to amplitude deviation.

[0014] In combination with some embodiments of the first aspect, in some embodiments, the step of determining the rear-end compensation value of the rear-end traveling wave signal based on the cable length from the connection point between the cables to the downstream monitoring terminal and the initial compensation value specifically includes: calculating the rear-end compensation value based on the attenuation function.

[0015] By adopting the above technical solution, the amplitude of the rear-end traveling wave signal is compensated, and the amplitude deviation caused by branch current changes and cable attenuation is effectively eliminated, so that the rear-end traveling wave signal can truly reflect the actual operating status of the cable, avoiding fault misjudgment and missed judgment due to amplitude deviation.

[0016] In combination with some embodiments of the first aspect, in some embodiments, after the step of comparing the absolute value with the relative change value, where the relative change value is the amplitude of the traveling wave current signal of the previous sampling point multiplied by a preset frequency threshold, the method further includes: when the absolute values ​​of the front-end traveling wave signal and the rear-end traveling wave signal are both greater than the corresponding relative change values; updating the adjacent monitoring terminal before the detection group to the detection group, and executing the step of determining the traveling wave current signal collected by the detection group as the front-end traveling wave signal according to the direction of the current, and determining the traveling wave current signal collected by the upstream monitoring terminal as the front-end traveling wave signal, and determining the traveling wave current signal collected by the downstream monitoring terminal as the rear-end traveling wave signal.

[0017] By adopting the above technical solution, when the absolute values ​​of the traveling wave signal at the front end and the traveling wave signal at the back end are both greater than the corresponding relative change values, it indicates that within the current detection group, a possible abnormality has occurred at the front end, while the probability of an abnormality at the back end is lower. The adjacent monitoring terminals before the detection group are updated to the detection group, allowing detection to be extended forward, focusing on areas where abnormalities may have occurred before, thereby improving the efficiency of cable fault warning.

[0018] In combination with some embodiments of the first aspect, in some embodiments, after the step of comparing the absolute value with the relative change value, where the relative change value is the amplitude of the traveling wave current signal of the previous sampling point multiplied by a preset frequency threshold, the method further includes: when the absolute values ​​of the front-end traveling wave signal and the rear-end traveling wave signal are not greater than the corresponding relative change values; updating the adjacent monitoring terminal after the detection group to the detection group, and executing the step of determining the traveling wave current signal collected by the detection group as the front-end traveling wave signal according to the direction of the current, and determining the traveling wave current signal collected by the upstream monitoring terminal as the front-end traveling wave signal, and determining the traveling wave current signal collected by the downstream monitoring terminal as the rear-end traveling wave signal.

[0019] By adopting the above technical solution, the detection can be extended backward, focusing on areas where abnormalities may exist in the future, thereby improving the efficiency of cable fault warning.

[0020] In a second aspect, the present application provides a cable fault warning system, which includes: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program code, the computer program code includes computer instructions, and the one or more processors call the computer instructions to enable the cable fault warning system to execute the method described in the first aspect and any possible implementation method of the first aspect.

[0021] In a third aspect, the present application provides a computer program product comprising instructions, which, when run on a cable fault warning system, enables the cable fault warning system to execute the method described in the first aspect and any possible implementation of the first aspect.

[0022] In a fourth aspect, the present application provides a computer-readable storage medium comprising instructions, which, when executed on a cable fault warning system, enable the cable fault warning system to execute the method described in the first aspect and any possible implementation of the first aspect.

[0023] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. Monitoring terminals are installed at both ends of the cable line, at intervals, at the connections between cables, and at the connections between cables and overhead sections. This layout enables the collection of traveling wave current signals from multiple key locations. The traveling wave current signals collected by the detection group are then divided into front-end and back-end traveling wave signals based on current direction, facilitating subsequent differentiated analysis. The absolute value of the amplitude difference is calculated at adjacent sampling points and compared with the relative change value (calculated by multiplying the amplitude of the traveling wave current signal at the previous sampling point by a preset frequency threshold). This screens out signal portions that have truly changed and may indicate a fault, avoiding misinterpreting normal fluctuations as fault signals. Then, when only the absolute value of the back-end traveling wave signal is greater than the corresponding relative change value, a fault is likely present, and the fault is likely to occur within the cable section covered by the detection group. Waveform segments within a preset time window before and after the starting point of the traveling wave are extracted to generate front-end and back-end feature segments, focusing on key waveform features and removing irrelevant interference information. These characteristic segments are discretized and Fourier transformed, and the complex waveforms in the time domain are converted into the frequency domain for analysis. Through relevant calculations in the frequency domain (such as calculating the product of the front-end discrete frequency domain and the conjugate of the back-end discrete frequency domain and obtaining the time domain cross-correlation function sequence through inverse Fourier transform), the time delay is calculated by searching for the peak position in the time domain cross-correlation function sequence, and then compared with the theoretical propagation time difference of the traveling wave calculated by combining the cable length between the detection groups. If the difference is greater than the threshold, the fault is determined to be a hidden danger and an early warning is triggered. The cable section with the fault risk is located, the fault repair efficiency is improved, and the normal power supply order and the normal operation of the power user are guaranteed.

[0024] 2. To address the potential branching structures of T-type cables, a step is added to determine whether there are any cable-to-cable connections (including T-type branch points) before the detection group. If not, the subsequent determination process continues as normal; if present, a series of targeted compensation operations are initiated. First, all cables connected to the connection (e.g., T-type branch point) are identified. Then, the monitoring terminal closest to the connection is searched for on all cables, and the branches and monitoring equipment at related locations that may affect the current of the current detection group are identified. Next, the change in the amplitude of the traveling wave current flowing into the cable where the detection group is located is calculated based on the impedance of the monitoring terminal to obtain an initial compensation value. This initial compensation value can quantify the current changes caused by factors such as the load differences between different branches at the T-type branch, accurately reflecting the impact of the branch current on the current amplitude of the main or branch line where the detection group is located. Then, the front-end compensation value for the front-end traveling wave signal and the back-end compensation value for the back-end traveling wave signal are determined based on the cable length from the cable connection (e.g., T-type branch point) to the upstream monitoring terminal and the downstream monitoring terminal, respectively. This takes into account the changes in the branch current during cable transmission at different locations and its impact on the front-end and back-end traveling wave signals. Finally, these compensation values ​​are used to compensate the corresponding relative change values ​​before executing the subsequent judgment steps. Through this compensation process that fits the actual situation of the T-type cable branch structure, the interference factors caused by the branch current change can be effectively eliminated, so that the subsequent judgment of whether the front-end and rear-end traveling wave signals are abnormal is more in line with the actual cable operation status, especially when the branch current fluctuates greatly, avoiding its normal fluctuation from being misjudged as a fault signal, and preventing early fault signals from being masked and missed, thereby improving the accuracy of fault warning judgment in T-type cable application scenarios.

[0025] 3. When calculating the change in the amplitude of the traveling wave current flowing into the cable where the detection group is located to obtain the initial compensation value, the first, second, and third monitoring terminals are determined based on the traveling wave distribution relationship. This step clarifies the role of each monitoring terminal in the traveling wave current distribution and lays the foundation for subsequent accurate calculations. Based on the wave impedance of each branch, a specific formula is used to calculate the compensation value for each transmission branch. The wave impedance reflects the electrical characteristics of the branch. The different wave impedances of different branches will cause changes such as shunting of the traveling wave current at the branch. By calculating the compensation value with the help of the formula, the current changes caused by the branch characteristics can be accurately quantified. In the T-type cable branch structure, the difference in the load of each branch will cause complex changes in the current magnitude and phase. By accurately calculating the transmission branch compensation value, the impact of the branch current change on the traveling wave current signal amplitude of the cable where the detection group is located can be effectively compensated, avoiding the normal fluctuation of the branch current being misjudged as a fault signal, or the early fault signal being masked and missed, thereby improving the accuracy and effectiveness of the T-type cable fault feature extraction and enhancing the reliability and accuracy of the entire cable fault warning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of a cable fault early warning method according to an embodiment of the present application; Figure 2 This is a schematic diagram of a solution for configuring a monitoring terminal in an embodiment of the present application; Figure 3 is a schematic diagram of another solution for configuring a monitoring terminal in an embodiment of the present application; Figure 4 is a schematic diagram of another solution for configuring a monitoring terminal in an embodiment of the present application; Figure 5 This is a structural diagram of an applicable system architecture of the cable fault early warning method in an embodiment of the present application; Figure 6 This is another flowchart of the cable fault early warning method in an embodiment of the present application; Figure 7 It is a schematic diagram of an exemplary hardware structure of the cable fault warning system in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The terms used in the following examples of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. As used in the specification and appended claims of the present application, the singular expressions "a," "an," "said," "above," "the," and "this" are intended to include plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used in the present application refers to and encompasses any or all possible combinations of one or more of the listed items.

[0028] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of this application, unless otherwise specified, "plurality" means two or more.

[0029] See also Figure 1 , Figure 1 This is a flow chart of a cable fault early warning method according to an embodiment of the present application; S101, selecting adjacent monitoring terminals as a detection group; the monitoring terminals are set at both ends of the cable line, at intervals, at the connection points between cables, and at the connection points between cables and overhead sections; It should be noted that there are many solutions for configuring monitoring terminals on cable lines in this embodiment, for example: See also Figures 2 to 4 , Figure 2This is a schematic diagram of a solution for configuring a monitoring terminal in an embodiment of the present application; Figure 3 is a schematic diagram of another solution for configuring a monitoring terminal in an embodiment of the present application; Figure 4 is a schematic diagram of another solution for configuring a monitoring terminal in an embodiment of the present application; In the case of pure cable lines, in principle, it is necessary to ensure that one set of monitoring terminals are configured at both ends of the cable line, and for the middle line part, it is configured according to the principle of adding one set of monitoring terminals for every preset kilometer.

[0030] For lines with special branching structures like T-junction cables, monitoring points should first be set up at both ends of the main line and at the T-junction. Furthermore, additional monitoring points should be added at predetermined intervals based on the length of the line.

[0031] For mixed-rack lines, that is, lines with overhead cables mixed in, first set up a monitoring point at the overhead cable mixing location (on the cable side). Then, install the cable section according to the configuration principles of a pure cable line.

[0032] Among them, the monitoring terminal refers to the equipment used to monitor the relevant electrical parameters of the cable line (such as traveling wave current signals, etc.), and the detection group refers to a set of adjacent monitoring terminals, which is used to monitor the cable lines within its coverage area for faults.

[0033] It should be noted that the system architecture revolves around cable fault monitoring and early warning, and consists of a monitoring terminal, a data center, and a client, connected via a wide area network. The details are as follows: See also Figure 5 , Figure 5 This is a structural diagram of an applicable system architecture of the cable fault early warning method in an embodiment of the present application; Monitoring Terminal: Attached to the terminal cable, it monitors and collects cable data in real time. Using a wired or wireless network, the collected data signals are uploaded to the data center, providing basic data for subsequent system analysis.

[0034] Data Center: Serving as the execution entity, it receives and analyzes data signals uploaded by monitoring terminals. It automatically stores the uploaded data signals and analysis results, provides a web service query function for users to easily access relevant information, and features SMS push notifications to promptly notify relevant personnel when anomalies occur. Furthermore, it sends analysis results to the client for display.

[0035] Client: Receives and displays data and analysis results sent by the data center. Users can obtain cable-related information through the client, understand the cable's operating status, and whether there are any potential fault hazards.

[0036] S102: Determine the traveling wave current signal collected by the detection group according to the direction of the current, the traveling wave current signal collected by the upstream monitoring terminal as the front-end traveling wave signal, and the traveling wave current signal collected by the downstream monitoring terminal as the rear-end traveling wave signal; The traveling wave current signal refers to a current fluctuation signal propagating in the cable due to a fault or other disturbance.

[0037] Specifically, after the detection group collects traveling wave current signals, these signals need to be classified and identified. Based on the actual flow direction of the current in the cable, the positions of the upstream and downstream monitoring terminals within the detection group are clearly defined. The traveling wave current signals collected by the upstream monitoring terminal are defined as the front-end traveling wave signals, and the signals collected by the downstream monitoring terminal are defined as the back-end traveling wave signals, so that subsequent targeted analysis and processing of signals from different directions can be performed.

[0038] In some embodiments, an electrical connection diagram of the cable line is obtained to clarify the direction of current flow; then, a current direction identifier is set for each monitoring terminal in the monitoring system, and the upstream and downstream monitoring terminals are determined based on the identifier; finally, in the signal acquisition module, the signal collected by the upstream monitoring terminal is marked as a front-end traveling wave signal, and the downstream is marked as a rear-end traveling wave signal according to the set rules, which is not limited here.

[0039] S103, calculating the absolute value of the amplitude difference between the traveling wave current signal at the next sampling point and the previous sampling point at adjacent sampling points; Adjacent sampling points refer to two sampling points that are adjacent in time or position when sampling the traveling wave current signal. The amplitude of the traveling wave current signal refers to its magnitude at a specific moment. The absolute value of the amplitude difference refers to the absolute value of the difference between the amplitude of the traveling wave current signal at the subsequent sampling point and the amplitude at the previous sampling point, and is used to reflect the degree of change in the signal amplitude.

[0040] Specifically, to analyze the changes in the traveling wave current signal, it is necessary to process the signal amplitude at adjacent sampling points. After sampling the traveling wave current signal, the amplitude data of adjacent sampling points is obtained. The difference between the amplitude of the subsequent sampling point and the amplitude of the previous sampling point is calculated, and the absolute value of this difference is taken. This is used to quantify the degree of change in the signal amplitude between adjacent sampling points, providing basic data for subsequent judgment of whether the signal is abnormal.

[0041] S104, comparing the absolute value with the relative change value, where the relative change value is the amplitude of the traveling wave current signal at the previous sampling point multiplied by a preset frequency threshold; The absolute value refers to the absolute value of the amplitude difference of the traveling wave current signals at adjacent sampling points calculated in step S103.

[0042] Specifically, to determine whether a change in the traveling wave current signal amplitude is abnormal, the absolute value of the calculated amplitude difference is compared with a reference value. This reference value is the relative change value, which is calculated by multiplying the traveling wave current signal amplitude at the previous sampling point by a preset frequency threshold. By comparing the absolute value with the relative change value, it is possible to determine whether the signal amplitude change is excessive.

[0043] It should be understood that there are three situations in the judgment result; different processing methods are used for different situations, namely step S105, step S110, and step S111.

[0044] S105, when only the absolute value of the rear-end traveling wave signal is greater than the corresponding relative change value; extracting waveform segments within a preset time window before and after the starting point of the traveling wave from the front-end traveling wave signal and the rear-end traveling wave signal, respectively, to generate a front-end feature segment and a rear-end feature segment; The starting point of the traveling wave refers to a point where the absolute value is greater than the relative change value; the preset time window refers to a pre-set time range used to determine the time interval for extracting waveform segments.

[0045] Specifically, if the amplitude variation of only the rear-end traveling wave signal exceeds the normal range, it indicates that the cable section covered by the inspection group may have a potential fault. To further analyze the fault characteristics, it is necessary to extract key waveform segments from the front-end and rear-end traveling wave signals. First, the starting point of the traveling wave is determined. Then, with this point as the center, waveform segments are extracted within a preset time window before and after it. These segments generate front-end characteristic segments and rear-end characteristic segments, respectively. These segments contain important information related to the fault and provide data support for subsequent signal processing and analysis.

[0046] S106, discretizing the front-end feature segments and the back-end feature segments to obtain a front-end discrete sequence and a back-end discrete sequence; and performing Fourier transform to obtain a front-end discrete frequency domain and a back-end discrete frequency domain; Discretization is the process of converting continuous waveform segments into discrete numerical sequences. Fourier transform is a mathematical transformation method that converts time-domain signals into frequency-domain signals and is used to analyze the frequency components of signals.

[0047] Specifically, to analyze the characteristics of the traveling wave current signal from different perspectives, the front-end and back-end characteristic segments need to be processed. First, they are discretized, converting the continuous waveform into a discrete numerical sequence for easier computer processing and analysis. Then, a Fourier transform is performed on the discretized sequence, converting the time-domain signal into the frequency domain, resulting in the front-end discrete frequency domain and the back-end discrete frequency domain. This transformation allows the frequency components of the signal to be analyzed, revealing more information related to the fault, providing a richer basis for subsequent determination of potential cable faults.

[0048] S107, calculating the product of the front-end discrete frequency domain and the conjugate of the back-end discrete frequency domain, and obtaining a time domain cross-correlation function sequence through inverse Fourier transform; It should be noted that, from a mathematical perspective, conjugate complex numbers possess unique properties in complex number operations. When a complex number is multiplied by its conjugate complex number, the result effectively normalizes the effects of the imaginary part, facilitating subsequent calculations and relationship analysis. For signals represented in the frequency domain as complex numbers, the conjugate of the back-end discrete frequency domain is taken before multiplication with the front-end discrete frequency domain.

[0049] In frequency-domain analysis, directly comparing the similarity and synchronization of the front-end and back-end traveling-wave current signals across various frequency components presents difficulties due to differences in signal phase and other factors. However, the conjugate multiplication operation properly addresses these phase-related obstacles, accurately highlighting their synchronization and similarity across frequency components, thereby more accurately measuring their correlation.

[0050] Furthermore, calculating the product of the front-end discrete frequency domain and the conjugate of the back-end discrete frequency domain is essentially exploring the degree of fit or correlation between the front-end and back-end signals within the frequency domain. The front-end and back-end traveling wave current signals can be likened to two objects with multidimensional characteristics, with each frequency component equivalent to one of these dimensions (i.e., a "link"). The product of the two can intuitively reflect the coordination between the two signals at each frequency dimension. If the resulting value of this product is large at a specific frequency, this means that the front-end and back-end traveling wave current signals exhibit strong similarity and correlation in terms of the corresponding frequency characteristics.

[0051] By calculating the product of the front-end discrete frequency domain and the conjugate of the back-end discrete frequency domain, a frequency-domain representation of the correlation between the two is obtained. However, the frequency-domain information is relatively abstract and not conducive to directly observing and analyzing the dynamic changes in the correlation between the signals over time. By converting it to the time domain with the help of the inverse Fourier transform and obtaining the time-domain cross-correlation function sequence, we can use time as the horizontal coordinate and the function value as the vertical coordinate to intuitively see the changes in the strength of the correlation between the front-end and back-end signals at different times. For example, the time point corresponding to the peak position in the time-domain cross-correlation function sequence is the moment when the correlation between the two signals is the strongest. The time corresponding to this peak position can be directly obtained from the time delay information, which can then be compared with the theoretically normal traveling wave propagation time to determine whether there are any potential fault hazards in the cable.

[0052] S108, searching for a peak position in the time domain cross-correlation function sequence, and calculating a time delay; The peak position refers to the point where the function value reaches the maximum value in the time domain cross-correlation function sequence, which reflects the moment when the correlation between the front-end and back-end signals is the strongest.

[0053] It should be noted that the cross-correlation function is used to measure the similarity between two signals at different time points. In the time domain, the peak position of the cross-correlation function generally indicates the optimal temporal alignment of the two signals. For the traveling wave current signals acquired from the front and back ends, by calculating their time-domain cross-correlation function sequences, the peak position corresponds to the time point when the two signals are most similar. The difference between these time points is the time delay, which reflects the time it takes for the traveling wave to propagate from the front to the back end.

[0054] However, the goal isn't just to find the single point in time when the correlation is strongest; more importantly, it's to analyze the time it takes for a traveling wave to propagate through the cable. Considering that a traveling wave propagates from the front end of the cable to the rear end, there should normally be a time difference between when the traveling wave signal is received at the front and rear ends. This time difference is known as the time delay. Specifically, the time delay is defined as the time from the first appearance of the front signal (which can be considered the starting time reference point) to when the rear signal reaches its strongest correlation with the front signal (i.e., the time point corresponding to the peak position). In cable fault warning scenarios, this time delay is closely related to the physical properties of the cable. Under normal circumstances, it follows certain patterns, depending on factors such as cable length and traveling wave propagation speed. For example, given a cable length of L and a traveling wave propagation speed of v, the theoretical time delay t is equal to L / v. However, cable faults, such as local damage that changes the properties of the propagation medium or poor contact at joints, can alter the traveling wave propagation speed, causing the actual time delay to differ from the theoretical value.

[0055] S109. Calculate the theoretical traveling wave propagation time difference based on the cable lengths between the detection groups. If the difference between the time delay and the theoretical traveling wave propagation time difference is greater than a threshold, determine that there is a potential fault in the cable section covered by the detection group and trigger an early warning.

[0056] The theoretical propagation time difference of the traveling wave refers to the time difference required for the traveling wave to propagate from the front end to the back end under normal circumstances, which is calculated based on theoretical parameters such as the cable length between the detection groups and the propagation speed of the traveling wave in the cable.

[0057] Specifically, to determine whether the cable section covered by the inspection group actually has a potential fault, it is necessary to compare the actual monitored time delay with the theoretical traveling wave propagation situation. First, based on relevant theoretical parameters such as the cable length between the inspection groups and the known propagation speed of traveling waves in such cables, the theoretical traveling wave propagation time difference is calculated using the corresponding physical calculation formula (such as time = distance ÷ speed). Then, the difference between the actual calculated time delay and this theoretical traveling wave propagation time difference is calculated and compared with a pre-set threshold. If the difference between the two is greater than the threshold, it means that the actual traveling wave propagation situation has deviated significantly from the theoretical situation, which is likely due to a potential fault in the cable. Therefore, the cable section covered by the inspection group is determined to have a potential fault and an early warning is triggered. Otherwise, the current cable section can be considered normal.

[0058] In some embodiments, the propagation velocity value v of the traveling wave in the current cable and the cable length L between the detection groups are obtained from the cable parameter configuration file; then, the theoretical propagation time difference t of the traveling wave is calculated using the formula t=L / v; then, the calculated time delay Δt is differenced with t to obtain the difference Δd (i.e., Δd=|Δt-t|); finally, Δd is compared with a preset threshold T. If Δd>T, it is determined that there is a potential fault and the early warning mechanism is triggered. Otherwise, it is considered normal and is not limited here.

[0059] As can be seen, monitoring terminals are installed at both ends of the cable line, at intervals, at the connections between cables, and at the connections between cables and overhead sections. This layout enables the collection of traveling wave current signals from multiple key locations. The traveling wave current signals collected by the detection group are then divided into front-end and back-end traveling wave signals based on current direction, facilitating subsequent differentiated analysis. The absolute value of the amplitude difference is calculated at adjacent sampling points and compared with the relative change value (calculated by multiplying the amplitude of the traveling wave current signal at the previous sampling point by a preset frequency threshold). This filter identifies signal portions that have genuine changes and may indicate a fault, avoiding misinterpreting normal fluctuations as fault signals. Then, if only the absolute value of the back-end traveling wave signal is greater than the corresponding relative change value, a fault is likely present, and the fault is likely to occur within the cable section covered by the detection group. Waveform segments within a preset time window before and after the starting point of the traveling wave are extracted to generate front-end and back-end feature segments, focusing on key waveform features and removing irrelevant interference information. These characteristic segments are discretized and Fourier transformed, and the complex waveforms in the time domain are converted into the frequency domain for analysis. Through relevant calculations in the frequency domain (such as calculating the product of the front-end discrete frequency domain and the conjugate of the back-end discrete frequency domain and obtaining the time domain cross-correlation function sequence through inverse Fourier transform), the time delay is calculated by searching for the peak position in the time domain cross-correlation function sequence, and then compared with the theoretical propagation time difference of the traveling wave calculated by combining the cable length between the detection groups. If the difference is greater than the threshold, the fault is determined to be a hidden danger and an early warning is triggered. The cable section with the fault risk is located, the fault repair efficiency is improved, and the normal power supply order and the normal operation of the power user are guaranteed.

[0060] In some embodiments, after step S104, the method further includes: S110 , when the absolute values ​​of the front-end traveling wave signal and the rear-end traveling wave signal are both greater than the corresponding relative change values; the adjacent monitoring terminal before the detection group is updated as the detection group, and step S102 is executed.

[0061] Specifically, when the absolute values ​​of the front-end traveling wave signal and the rear-end traveling wave signal are both greater than the corresponding relative change values, it means that within the cable section covered by the current detection group, the front-end area is more likely to have an abnormality, while the probability of fault-related abnormalities occurring at the rear end is relatively low. In order to more accurately and comprehensively check for possible hidden faults, it is necessary to adjust the detection range at this time. Update the adjacent monitoring terminals before the detection group to a new detection group, so that the monitoring range can be extended forward, focusing on areas where abnormalities may have existed before. Then, re-execute the operation of distinguishing the traveling wave current signals collected by the detection group according to the direction of the current, and again determine that the traveling wave current signal collected by the upstream monitoring terminal in the new detection group is the front-end traveling wave signal, and the signal collected by the downstream monitoring terminal is the rear-end traveling wave signal, so that the subsequent analysis and judgment can continue to be carried out according to the established fault warning process, thereby improving the efficiency and accuracy of the cable fault warning and avoiding missing possible fault points in the front-end area.

[0062] It can be seen that when the absolute values ​​of the traveling wave signals at the front end and the back end are both greater than the corresponding relative change values, an abnormality may have occurred at the front end, while the probability of an abnormality at the back end is lower. Updating the adjacent monitoring terminals before the detection group to the detection group allows the detection to be extended forward, focusing on areas where abnormalities may have occurred before, improving the efficiency of cable fault warning.

[0063] In some embodiments, after step S104, the method further includes: S111 , when the absolute values ​​of the front-end traveling wave signal and the rear-end traveling wave signal are both not greater than the corresponding relative change values, executing step S102 .

[0064] Specifically, when the absolute values ​​of the front-end traveling wave signal and the rear-end traveling wave signal are not greater than the corresponding relative change values, it means that within the cable section covered by the current detection group, the rear-end area is more likely to have fault-related abnormalities, while the front-end is relatively less likely to have abnormalities. In order to more carefully investigate potential faults, the detection range must be adjusted. Update the adjacent monitoring terminals after the detection group to a new detection group. In this way, the monitoring range can be extended backward, focusing on monitoring areas where abnormalities may exist in the future. Then, re-execute the operation of distinguishing the traveling wave current signals collected by the detection group according to the current direction, and again determine that the traveling wave current signal collected by the upstream monitoring terminal in the new detection group is the front-end traveling wave signal, and the signal collected by the downstream monitoring terminal is the rear-end traveling wave signal. Then, the subsequent fault warning process can be used to continue analysis and judgment, thereby improving the efficiency of cable fault warning, ensuring that possible fault points in the rear-end area are not missed, and more comprehensively guaranteeing the safe operation of the cable line.

[0065] It can be seen that the detection can be extended backward, focusing on areas where abnormalities may exist later, thereby improving the efficiency of cable fault warning.

[0066] In actual use, the branching structure of a T-type cable causes current to be split when the traveling wave propagates to the branch point. The varying load conditions of each branch can cause variations in the magnitude and phase of the branch current, which in turn affects the amplitude variation pattern of the traveling wave current signal. For example, when a branch is connected to a large number of high-power devices, the start-up or shutdown of these devices can cause large fluctuations in the current in that branch. These fluctuations are transmitted to the main line and other branch lines, causing complex variations in the amplitude difference of the traveling wave current signal at adjacent sampling points. According to the logic in step S104, which relies on comparing the absolute value of the amplitude difference with the relative change value (preset frequency threshold) to determine whether to extract a feature segment, the normal amplitude fluctuations caused by the branch current are likely to meet the threshold condition and be mistakenly identified as a fault signal, resulting in feature segment extraction. Conversely, some early fault signal amplitude changes may be masked by normal branch current fluctuations and fail to reach the threshold, resulting in missed fault detection and seriously affecting the accuracy and effectiveness of fault feature extraction.

[0067] See also Figure 6 , Figure 6 This is another flowchart of the cable fault early warning method in an embodiment of the present application; Therefore, in some embodiments, after step S104, the following steps are further included: S201, determining whether there are any connections between cables before the detection group; According to the above embodiments, the connection points between the cables are also provided with detection terminals; The connection points between cables refer to the locations where two or more cables are connected to each other, such as T-type branch points. The electrical characteristics at these connection points will affect the propagation of traveling wave current.

[0068] In some embodiments, the location information of the current detection group is obtained from the cable line database, and then the cable topology structure upstream of the location is queried, the connection locations between all cables are marked, and finally it is determined whether these connections are located before the detection group.

[0069] S202: If not, execute step S105; This step is performed when step S201 determines that there is no connection between the cables before the detection group. It is suitable for scenarios where the cable line structure is relatively simple and there are no branch connections that may affect the propagation of traveling wave current.

[0070] S203, if it exists, determine all cables connected to the connection point between the cables, and then search for the defined monitoring terminal closest to the connection point between the cables on all the cables; Here, "all cables" refers to all cables connected to the cable junctions, including trunk cables and branch cables. Specifically, if a junction exists in the test group, first identify all cables connected to that junction. These cables may include the trunk cable and multiple branch cables. Then, locate the monitoring terminals closest to the junction on each of these cables. These monitoring terminals can most directly reflect the changes in the traveling wave current at the junction. Targeting these monitoring terminals facilitates the subsequent accurate calculation of the compensation value for current changes caused by the branch structure.

[0071] S204. Calculate the amplitude change of the traveling wave current flowing into the cable where the detection group is located based on the impedance of the monitoring terminal to obtain an initial compensation value; The impedance of the monitoring terminal refers to the equivalent impedance of the cable at the location of the monitoring terminal, which reflects the obstruction of the cable to the traveling wave current.

[0072] The traveling wave current amplitude variation refers to the variation in the traveling wave current amplitude flowing into the cable where the detection group is located due to the existence of the branch structure compared with the case where there is no branch.

[0073] The initial compensation value is a value calculated based on the impedance of the monitoring terminal and is used to compensate for the effect of the branch structure on the traveling wave current amplitude.

[0074] Specifically, the change in the traveling wave current amplitude flowing into the cable where the detection group is located is calculated based on the impedance of the monitoring terminal. In a T-shaped cable branching structure, the varying loads between branches can cause the traveling wave current to shunt at the junction, affecting the current amplitude in the cable where the detection group is located. By calculating the relationship between impedance and current, the change in current amplitude due to the branching structure can be determined. This value is used as the initial compensation value for subsequent compensation of the traveling wave signal.

[0075] In some specific embodiments, step S204 specifically includes: S2041. Based on the traveling wave allocation relationship, determine the allocated defined monitoring terminal as the first monitoring terminal; determine the allocated defined monitoring terminal on the same cable as the detection group as the second monitoring terminal; and determine another allocated defined monitoring terminal as the third monitoring terminal. The traveling wave distribution relationship refers to the law by which the traveling wave current is distributed between different branch cables and related monitoring terminals at the connection points between cables (such as T-type branch points, etc.) based on the electrical characteristics (such as wave impedance, etc.) and connection conditions of each connected cable.

[0076] Definition: A monitoring terminal is a device that is pre-installed on a cable line and is used to collect relevant electrical parameters such as traveling wave current signals to assist in analyzing the cable's operating status and fault conditions.

[0077] The first monitoring terminal refers to a defined monitoring terminal that is determined to be in a specific position and has a specific role in the current distribution process based on the traveling wave distribution relationship. It plays a key reference role in the subsequent calculation of the traveling wave current amplitude change and other aspects.

[0078] The second monitoring terminal refers to another defined monitoring terminal that is in the same cable as the detection group and is distinguished under the traveling wave distribution relationship. It is closely related to the current situation of the cable where the detection group is located and can be used to compare and analyze current changes.

[0079] The third monitoring terminal refers to another defined monitoring terminal determined at other branches, etc., in addition to the assigned defined monitoring terminal on the same cable as the detection group. It is also important in reflecting the distribution of traveling wave current in different branches.

[0080] S2042, determining an initial compensation value according to an initial compensation value calculation function; The initial compensation value calculation function is: Where, is the equivalent wave impedance at the connection point between cables; is the transmission coefficient of the cable between the first monitoring terminal and the connection point between the cables; is the current value of the cable between the first monitoring terminal and the connection point between the cables; is the theoretical current value of the cable between the second monitoring terminal and the connection point between the cables, is the initial compensation value.

[0081] As can be seen, when calculating the change in the traveling wave current amplitude flowing into the cable where the detection group is located to obtain the initial compensation value, the first, second, and third monitoring terminals are determined based on the traveling wave distribution relationship. This step clarifies the role of each monitoring terminal in the traveling wave current distribution, laying the foundation for subsequent accurate calculations. Based on the wave impedance of each branch, a specific formula is used to calculate the compensation value for each transmission branch. Wave impedance reflects the electrical characteristics of the branch. Different wave impedances of different branches can cause changes in the traveling wave current, such as shunting, at the branch. Using the formula to calculate the compensation value, it is possible to accurately quantify the current changes caused by these branch characteristics. In a T-type cable branch structure, differences in branch loads can cause complex variations in current magnitude and phase. By accurately calculating the transmission branch compensation value, the impact of branch current changes on the traveling wave current signal amplitude of the cable where the detection group is located can be effectively compensated. This prevents normal branch current fluctuations from being misidentified as fault signals, or early fault signals from being masked and missed. This improves the accuracy and effectiveness of fault feature extraction for T-type cables and enhances the reliability and accuracy of the entire cable fault warning system.

[0082] S205, determining a front-end compensation value of a front-end traveling wave signal based on a cable length from a cable connection point to an upstream monitoring terminal and an initial compensation value; determining a rear-end compensation value of a rear-end traveling wave signal based on a cable length from a cable connection point to a downstream monitoring terminal and an initial compensation value; Specifically, considering that traveling wave currents attenuate over distance as they propagate through cables, the initial compensation value is modified based on the cable length from the cable connection point to the upstream and downstream monitoring terminals. The longer the cable, the greater the attenuation of the traveling wave current. Therefore, adjusting the initial compensation value based on the cable length yields more accurate front-end and back-end compensation values, which are used to compensate for the front-end and back-end traveling wave signals, respectively.

[0083] In some specific embodiments, step S205 specifically includes: S2051, calculating the front-end compensation value according to the attenuation function; calculating the back-end compensation value according to the attenuation function The decay function is: Where, is the compensation value, is the amplitude after reverse attenuation, is the original amplitude, is the cable attenuation constant, is the cable length, is the initial compensation value.

[0084] It can be seen that when determining the front-end compensation value of the front-end traveling wave signal, the amplitude measured by the monitoring terminal is first subjected to reverse attenuation processing to calculate the amplitude just after leaving the T-type branch point, and then the current amplitude change caused by factors such as traveling wave distribution at the T-type branch point is added to obtain the original amplitude. Finally, the final compensation value is determined by calculating the difference between the original amplitude and the amplitude measured by the monitoring terminal. In the T-type cable branch structure, the transmission of the traveling wave current signal is affected by both the branch characteristics and the cable attenuation. Through the above steps, the amplitude of the front-end traveling wave signal is compensated, and the amplitude deviation caused by the branch current change and the cable attenuation is effectively eliminated, so that the front-end traveling wave signal can truly reflect the actual operating status of the cable, avoiding fault misjudgment and missed judgment due to amplitude deviation.

[0085] It can be seen that compensating the amplitude of the rear-end traveling wave signal can effectively eliminate the amplitude deviation caused by branch current changes and cable attenuation, so that the rear-end traveling wave signal can truly reflect the actual operating status of the cable and avoid fault misjudgment and missed judgment due to amplitude deviation.

[0086] S206 , using the front-end compensation value to compensate for the relative change value corresponding to the front-end traveling wave signal, and using the back-end compensation value to compensate for the relative change value corresponding to the back-end traveling wave signal; and executing step S105 .

[0087] In some embodiments, the front-end compensation value is added to the corresponding relative change value to complete the compensation; similarly, the back-end compensation value is added to the corresponding relative change value to complete the compensation.

[0088] As can be seen, to address the potential branching structures of T-type cables, an additional step is required to determine whether there are any cable-to-cable connections (here, connections include T-type branch points) before the detection group. If not, the normal process continues; if present, a series of targeted compensation operations are initiated. First, all cables connected to the connection (e.g., T-type branch point) are identified. The monitoring terminal closest to the connection is then located on each cable, identifying the branches and monitoring equipment at the relevant locations that may affect the current of the current detection group. Next, the amplitude change of the traveling wave current flowing into the cable where the detection group is located is calculated based on the impedance of the monitoring terminal to obtain an initial compensation value. This initial compensation value quantifies the current changes caused by factors such as the load differences between different branches at the T-type branch, accurately reflecting the impact of the branch current on the current amplitude of the main or branch line where the detection group is located. The front-end compensation value for the front-end traveling wave signal and the rear-end compensation value for the rear-end traveling wave signal are then determined based on the cable length from the cable-to-cable connection (e.g., T-type branch point) to the upstream and downstream monitoring terminals, respectively. This takes into account the changes in the branch current during transmission at different cable locations and its impact on the front-end and rear-end traveling wave signals. Finally, these compensation values ​​are used to compensate the corresponding relative change values ​​before executing the subsequent judgment steps. Through this compensation process that fits the actual situation of the T-type cable branch structure, the interference factors caused by the branch current change can be effectively eliminated, so that the subsequent judgment of whether the front-end and rear-end traveling wave signals are abnormal is more in line with the actual cable operation status, especially when the branch current fluctuates greatly, avoiding its normal fluctuation from being misjudged as a fault signal, and preventing early fault signals from being masked and missed, thereby improving the accuracy of fault warning judgment in T-type cable application scenarios.

[0089] The following introduces an exemplary cable fault warning system 700 provided in an embodiment of the present application. Figure 7 Schematic diagram of an exemplary hardware structure of the cable fault warning system 700 provided in an embodiment of the present application.

[0090] In some embodiments, the cable fault warning system 700 is a computer device or the cable fault warning system 700 includes a computer device. The computer device includes a processor, a memory, and a network interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store data. The network interface of the computer device is used to communicate with other external terminals or servers via a network connection. In some embodiments, the network interface can be a wired network interface, and in some embodiments, the network interface can also be a wireless network interface. When the computer program is executed by the processor, the method in the embodiment of the present application is implemented.

[0091] Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0092] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0093] As used in the above embodiments, the term “when” may be interpreted to mean “if” or “after” or “in response to determining that” or “in response to detecting that”, depending on the context. Similarly, the phrases “upon determining that” or “if (stated condition or event) is detected” may be interpreted to mean “if determining that” or “in response to determining that” or “upon detecting (stated condition or event)” or “in response to detecting (stated condition or event)”, depending on the context.

[0094] In the above embodiments, all or part of the embodiments can be implemented using software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that can be accessed by a computer, or a data storage device such as a server or data center that integrates one or more available media. The available medium can be magnetic media (e.g., floppy disk, hard disk, tape), optical media (e.g., DVD), or semiconductor media (e.g., solid-state drive).

[0095] Those skilled in the art will appreciate that all or part of the process steps in the above-described method embodiments can be implemented by a computer program instructing the relevant hardware. The program can be stored in a computer-readable storage medium, and when executed, the program can include the process steps in the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM or random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A cable fault early warning method, characterized in that: include: Select adjacent monitoring terminals as a detection group; The monitoring terminals are set at both ends of the cable line, at intervals, at the connection points between cables, and at the connection points between cables and overhead sections; According to the direction of the current, the traveling wave current signal collected by the detection group is determined as the front-end traveling wave signal by the upstream monitoring terminal and the traveling wave current signal collected by the downstream monitoring terminal as the rear-end traveling wave signal; Calculate the absolute value of the amplitude difference between the traveling wave current signal at the next sampling point and the previous sampling point at adjacent sampling points; Comparing the absolute value with a relative change value, where the relative change value is the amplitude of the traveling wave current signal at the previous sampling point multiplied by a preset frequency threshold; When only the absolute value of the rear-end traveling wave signal is greater than the corresponding relative change value; extracting waveform segments within a preset time window before and after the starting point of the traveling wave from the front-end traveling wave signal and the rear-end traveling wave signal respectively to generate a front-end characteristic segment and a rear-end characteristic segment; Discretizing the front-end feature segment and the back-end feature segment respectively to obtain a front-end discrete sequence and a back-end discrete sequence; and performing Fourier transform to obtain a front-end discrete frequency domain and a back-end discrete frequency domain; Calculating the product of the front-end discrete frequency domain and the conjugate of the back-end discrete frequency domain, and obtaining a time domain cross-correlation function sequence by inverse Fourier transform; Searching for a peak position in the time domain cross-correlation function sequence and calculating a time delay; Calculating the theoretical propagation time difference of the traveling wave according to the cable length between the detection groups; If the difference between the time delay and the theoretical propagation time difference of the traveling wave is greater than a threshold, it is determined that there is a potential fault in the cable section covered by the detection group and an early warning is triggered.

2. The method according to claim 1, characterized in that After the step of comparing the absolute value with the relative change value, where the relative change value is the amplitude of the traveling wave current signal at the previous sampling point multiplied by a preset frequency threshold, the method further includes: Determine whether there are any connections between cables before the detection group; If not, executing the step when only the absolute value of the rear-end traveling wave signal is greater than the corresponding relative change value; If it exists, determine all cables connected to the connection point between the cables, and then search for the defined monitoring terminal closest to the connection point between the cables from all cables; According to the impedance of the monitoring terminal, the amplitude change of the traveling wave current flowing into the cable where the detection group is located is calculated to obtain the initial compensation value; Determine the front-end compensation value of the front-end traveling wave signal based on the cable length from the cable connection point to the upstream monitoring terminal and the initial compensation value; determine the rear-end compensation value of the rear-end traveling wave signal based on the cable length from the cable connection point to the downstream monitoring terminal and the initial compensation value; The front-end compensation value is used to compensate for the relative change value corresponding to the front-end traveling wave signal, and the rear-end compensation value is used to compensate for the relative change value corresponding to the rear-end traveling wave signal; and the steps are performed when only the absolute value of the rear-end traveling wave signal is greater than the corresponding relative change value.

3. The method according to claim 2, characterized in that The step of calculating the amplitude change of the traveling wave current flowing into the cable where the detection group is located to obtain the initial compensation value based on the impedance of the monitoring terminal specifically includes: Based on the distribution relationship of the traveling waves, the assigned defined monitoring terminal is determined as the first monitoring terminal; the assigned defined monitoring terminal on the same cable as the detection group is determined as the second monitoring terminal, and the other assigned defined monitoring terminal is determined as the third monitoring terminal; Determine the initial compensation value according to the initial compensation value calculation function; The initial compensation value calculation function is: Where, is the equivalent wave impedance at the connection point between cables; is the transmission coefficient of the cable between the first monitoring terminal and the connection point between the cables; is the current value of the cable between the first monitoring terminal and the connection point between the cables; is the theoretical current value of the cable between the second monitoring terminal and the connection point between the cables, is the initial compensation value.

4. The method according to claim 3, characterized in that The cable length and initial compensation value based on the connection point between the cables to the upstream monitoring terminal; The step of determining the front-end compensation value of the front-end traveling wave signal specifically includes: Calculate the front-end compensation value according to the attenuation function; The decay function is: Where, is the compensation value, is the amplitude after reverse attenuation, is the original amplitude, is the cable attenuation constant, is the cable length, is the initial compensation value.

5. The method according to claim 4, characterized in that The step of determining the rear-end compensation value of the rear-end traveling wave signal based on the cable length from the cable connection point to the downstream monitoring terminal and the initial compensation value specifically includes: The back-end compensation value is calculated according to the attenuation function.

6. The method according to claim 1, characterized in that After the step of comparing the absolute value with the relative change value, where the relative change value is the amplitude of the traveling wave current signal at the previous sampling point multiplied by a preset frequency threshold, the method further includes: When the absolute values ​​of the front-end traveling wave signal and the rear-end traveling wave signal are both greater than the corresponding relative change values; Update the adjacent monitoring terminal before the detection group to the detection group, and execute the steps of determining the traveling wave current signal collected by the detection group according to the direction of the current, and determining the traveling wave current signal collected by the upstream monitoring terminal as the front-end traveling wave signal, and the traveling wave current signal collected by the downstream monitoring terminal as the rear-end traveling wave signal.

7. The method according to claim 1, characterized in that After the step of comparing the absolute value with the relative change value, where the relative change value is the amplitude of the traveling wave current signal at the previous sampling point multiplied by a preset frequency threshold, the method further includes: When the absolute values ​​of the front-end traveling wave signal and the rear-end traveling wave signal are not greater than the corresponding relative change values; Update the adjacent monitoring terminal after the detection group to the detection group, and execute the steps of determining the traveling wave current signal collected by the detection group according to the direction of the current, the traveling wave current signal collected by the upstream monitoring terminal as the front-end traveling wave signal, and the traveling wave current signal collected by the downstream monitoring terminal as the rear-end traveling wave signal.

8. A cable fault early warning system, characterized in that: The cable fault warning system includes: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program code, the computer program code includes computer instructions, and the one or more processors call the computer instructions to enable the cable fault warning system to execute the method described in any one of claims 1 to 7.

9. A computer program product comprising instructions, characterized in that When the computer program product is run on a cable fault early warning system, the cable fault early warning system is enabled to perform the method according to any one of claims 1 to 7.

10. A computer-readable storage medium comprising instructions, characterized in that: When the instruction is executed on the cable fault warning system, the cable fault warning system is caused to execute the method according to any one of claims 1 to 7.

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