A high resistance ground fault identification method, device, equipment, medium and product for a power distribution line

Abstract

This invention discloses a method, device, equipment, medium, and product for identifying high-resistance grounding faults in power distribution lines, relating to the field of power distribution line grounding fault detection technology. It utilizes a high-resistance grounding fault identification device that can be directly externally installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on one end of the tower of the power distribution line under test. By acquiring real-time line electrical signals of the power distribution line under test, grounding disturbance judgment is first performed based on the acquired signals. Only when a suspected grounding disturbance is detected is the disturbance traveling wave signal specifically extracted and preprocessed. Grounding fault identification is then completed based on the preprocessed clean traveling wave signal. This achieves low-cost, high-reliability identification of high-resistance grounding faults in existing power distribution network scenarios, providing timely and accurate evidence for rapid fault handling in power distribution networks and effectively ensuring the safe and stable operation of the power distribution network.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution line ground fault detection, and in particular to a high-resistance ground fault identification method, device, equipment, medium and product for a power distribution line. BACKGROUND

[0002] With the continuous development of the power system and the increasing demand of terminal users for power supply reliability and stability, the safe and reliable operation of the distribution network, as the key link directly facing the terminal load, is crucial to the protection of production and life order.

[0003] The distribution network usually adopts the neutral point non-effective grounding mode. When a single-phase ground fault occurs on the line, especially a high-resistance ground fault, the fault characteristics are relatively concealed. The line can be operated for a short time, but if the fault cannot be identified and disposed in time, long-term operation with the fault may cause damage to the insulation of the line and equipment, and even cause the expansion of the fault range, posing a potential threat to the safe and stable operation of the power system. Therefore, reliable identification of such faults is of great significance to improving the operation and maintenance efficiency of the distribution network and ensuring power supply continuity.

[0004] Currently, primary and secondary integrated pole-mounted circuit breakers have become widely used protection devices in distribution network lines. They have basic fault section isolation and operation monitoring functions, and can effectively protect the line when a regular fault occurs, providing a foundation for improving the automation level of the distribution network. However, the current identification scheme for high-resistance ground faults has obvious shortcomings. If the fault identification accuracy is to be improved, the existing on-site switch devices usually need to be replaced or extensively modified, which not only complicates the construction process, but also incurs high modification costs, making it difficult to be widely applied. The traditional identification method relying on existing stock equipment also cannot distinguish various transient disturbance interferences in the line, and the reliability and accuracy of high-resistance ground fault identification are low. After a fault occurs, effective disposal cannot be carried out in time, prolonging the period of fault troubleshooting and power supply restoration. The existing technology cannot effectively identify high-resistance ground faults at a low cost, and cannot meet the actual needs of the high-reliability operation of the current distribution network. SUMMARY

[0005] The present application provides a high-resistance ground fault identification method, device, equipment, medium and product for a power distribution line, which solves the technical problem that the existing high-resistance ground fault identification technology cannot simultaneously consider low-cost deployment and high-reliable identification, and cannot effectively ensure the safe and stable operation of the distribution network.

[0006] The first aspect of this invention provides a method for identifying high-resistance grounding faults in power distribution lines, applied to a high-resistance grounding fault identification device. The high-resistance grounding fault identification device is installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on one end of the power distribution line under test. The high-resistance grounding fault identification method includes: Collect the real-time line electrical signal of the power distribution line under test; The grounding disturbance is determined using the real-time line electrical signal. When the ground disturbance determination result is that there is a suspected ground disturbance, the disturbance traveling wave signal is extracted from the real-time line electrical signal and preprocessed to obtain the preprocessed traveling wave signal. The ground fault identification result of the tested power distribution line is obtained by using the preprocessed traveling wave signal for ground fault identification.

[0007] Optionally, the step of using the real-time line electrical signal to determine grounding disturbance includes: Extract the power frequency zero-sequence component and high-frequency transient component of the real-time line electrical signal; Determine whether the power frequency zero-sequence component meets the preset power frequency determination condition, and determine whether the high-frequency transient component meets the preset high-frequency determination condition; If the preset power frequency determination condition or the preset high frequency determination condition is not met, it is determined that there is no suspected grounding disturbance in the tested power distribution line, and this is taken as the grounding disturbance determination result. When both the preset power frequency determination condition and the preset high frequency determination condition are met simultaneously, the tested power distribution line is determined to have a suspected grounding disturbance, and this is taken as the grounding disturbance determination result.

[0008] Optionally, the power frequency zero-sequence component includes power frequency zero-sequence voltage and power frequency zero-sequence current, and the preset power frequency determination condition specifically is that the power frequency zero-sequence voltage exceeds the preset normal voltage fluctuation range, and the power frequency zero-sequence current is lower than the preset current threshold. The preset high-frequency determination condition is specifically that the high-frequency transient component has an amplitude change, and the amplitude of the change is higher than the preset environmental high-frequency noise amplitude threshold.

[0009] Optionally, when the ground disturbance determination result indicates the existence of a suspected ground disturbance, the disturbance traveling wave signal is extracted from the real-time line electrical signal and preprocessed to obtain a preprocessed traveling wave signal, including: When the ground disturbance determination result is that there is a suspected ground disturbance, the disturbance traveling wave signal during the disturbance occurrence period is extracted from the real-time line electrical signal and filtered to obtain the filtered traveling wave signal. The filtered traveling wave signal is denoised to obtain a denoised traveling wave signal; According to the preset number of decomposition layers, the noise-reduced traveling wave signal is subjected to discrete wavelet decomposition to obtain a set of layered wavelet coefficients; Effective high-frequency detail coefficients are extracted from the hierarchical wavelet coefficient set to obtain an effective high-frequency detail coefficient sequence; Detect traveling wave abrupt change feature points from the effective high-frequency detail coefficient sequence and extract the corresponding effective high-frequency detail coefficients; The effective high-frequency detail coefficients corresponding to each of the abrupt feature points are removed by reflection wave elimination, and then a discrete wavelet inverse transform is performed to obtain a preprocessed traveling wave signal.

[0010] Optionally, the step of using the preprocessed traveling wave signal to perform ground fault identification and obtain the ground fault identification result of the tested power distribution line includes: The preprocessed traveling wave signal is subjected to variational mode decomposition to obtain multiple sets of intrinsic mode components; Wavelet packet energy spectrum analysis was performed on the intrinsic mode components of each group, and multi-dimensional fault quantification indicators were extracted from the analysis results. Calculate the kurtosis value of each group of intrinsic mode components, and extract effective fault quantification indicators from the multi-dimensional fault quantification indicators based on the kurtosis value; The effective fault quantification index is normalized and combined with preset weights to construct a standardized fault feature vector. The standardized fault feature vector is matched with a preset fault sample library, and the ground fault type is determined based on the matching result, which is then used as the ground fault identification result.

[0011] Optionally, another high-resistance grounding fault identification device is installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on the other end of the tower of the tested power distribution line. When the grounding fault identification result indicates that a high-resistance grounding fault exists in the tested power distribution line, the device further includes: Read the absolute arrival time of the first fault traveling wave recorded in the high-resistance grounding fault identification device; Read the absolute arrival time of the second fault traveling wave recorded in the other high-resistance ground fault identification device; According to the line type of the power distribution line under test, a preset line traveling wave propagation velocity table is retrieved, and the corresponding line traveling wave propagation velocity is matched. The target difference is obtained by calculating the difference between the absolute arrival times of the first fault traveling wave and the second fault traveling wave. The target multiplication value is obtained by multiplying the target difference with the traveling wave propagation speed of the line. The target sum is obtained by performing a summation operation using the target multiplier and the preset length of the main trunk of the power distribution line under test. The distance from the fault point to the high-resistance grounding fault identification device is obtained by calculating the ratio between the target sum and the line geometric correction coefficient.

[0012] The second aspect of this invention provides a high-resistance grounding fault identification device for power distribution lines. The device is installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on one end of the power distribution line under test. The high-resistance grounding fault identification device includes: A wideband current transformer is used to collect the real-time line electrical signal of the power distribution line under test. The suspected disturbance detection module is used to determine ground disturbances using the real-time line electrical signal. The traveling wave preprocessing module is used to extract the disturbance traveling wave signal from the real-time line electrical signal and perform preprocessing when the ground disturbance determination result is that there is a suspected ground disturbance, so as to obtain the preprocessed traveling wave signal. The fault identification and judgment module is used to identify ground faults using the preprocessed traveling wave signal to obtain the ground fault identification result of the tested power distribution line.

[0013] A third aspect of the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the high-resistance grounding fault identification method for power distribution lines as described above.

[0014] The fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed, implements the high-resistance grounding fault identification method for power distribution lines as described above.

[0015] The fifth aspect of the present invention provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, wherein, when the program instructions are executed by a computer, the computer performs the high-resistance grounding fault identification method for power distribution lines as described above.

[0016] As can be seen from the above technical solutions, the present invention has the following advantages: This invention provides a method, device, equipment, medium, and product for identifying high-resistance grounding faults in power distribution lines. It utilizes a high-resistance grounding fault identification device that can be directly externally installed between the primary and secondary integrated pole-mounted circuit breaker and the feeder terminal on one end of the tower of the power distribution line under test. This innovative external installation design eliminates the need to modify or replace existing distribution network switchgear; system upgrades can be completed through rapid on-site deployment, completely avoiding the huge investment and complex construction requirements associated with replacing complete sets of switches, and significantly lowering the engineering threshold for technology promotion. This invention collects real-time line electrical signals from the power distribution line under test, first determining grounding disturbances based on the collected signals, and only identifying suspected grounding disturbances. During disturbances, the system extracts and preprocesses the disturbance traveling wave signal, and then identifies ground faults based on the preprocessed clean traveling wave signal. Through the signal processing logic of first determining and then processing, it effectively filters out various transient interferences caused by non-grounding disturbances during line operation, accurately captures the weak transient characteristics of high-resistance ground faults, and effectively overcomes the shortcomings of traditional identification methods, such as susceptibility to interference, difficulty in distinguishing between fault and non-fault disturbances, and insufficient identification reliability. It significantly improves the accuracy and stability of high-resistance ground fault identification, realizes low-cost and high-reliability identification of high-resistance ground faults in existing distribution network scenarios, provides timely and accurate basis for rapid handling of distribution network faults, and effectively ensures the safe and stable operation of the distribution network. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of the steps of a method for identifying high-resistance grounding faults in power distribution lines, provided in Embodiment 1 of the present invention. Figure 2 This is a flowchart illustrating the steps of a method for identifying high-resistance grounding faults in power distribution lines, provided in Embodiment 2 of the present invention. Figure 3 This is a schematic diagram of the single-end external mounting structure of the high-resistance grounding fault identification device provided in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the dual-end external mounting structure of the high-resistance grounding fault identification device provided in Embodiment 2 of the present invention; Figure 5 This is a structural block diagram of a high-resistance grounding fault identification device for power distribution lines provided in Embodiment 3 of the present invention; Figure 6This is a structural block diagram of an electronic device provided in Embodiment 4 of the present invention. Detailed Implementation

[0019] This invention provides a method, apparatus, equipment, medium, and product for identifying high-resistance grounding faults in power distribution lines, which addresses the technical problem that existing high-resistance grounding fault identification technologies cannot simultaneously achieve low-cost deployment and high-reliability identification, thus failing to effectively ensure the safe and stable operation of the power distribution network.

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 , Figure 1 This is a flowchart of the steps for identifying high-resistance grounding faults in power distribution lines, as provided in Embodiment 1 of the present invention.

[0022] This invention provides a method for identifying high-resistance grounding faults in power distribution lines. The method is applied to a high-resistance grounding fault identification device, which is installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on one end of the tower of the power distribution line under test. The high-resistance grounding fault identification method includes: Step 101: Collect the real-time line electrical signal of the power distribution line under test.

[0023] In this embodiment of the invention, the high-resistance grounding fault identification device collects the three-phase current and three-phase voltage signals of the tested distribution line in real time through its signal acquisition interface connected to the secondary side of the primary and secondary integrated pole-mounted circuit breaker; at the same time, the device directly outputs the line electrical signal to the feeder terminal (FTU) without changing the original signal transmission link between the equipment, thus ensuring the normal operation of the original protection and monitoring functions of the distribution network.

[0024] Step 102: Use real-time line electrical signals to determine grounding disturbances.

[0025] In this embodiment of the invention, the high-resistance grounding fault identification device performs a preliminary analysis on the real-time line electrical signal acquired in step 101, extracts preset disturbance judgment feature quantities from the three-phase voltage and current signals, and compares the feature quantities with the disturbance judgment threshold built into the device. If the feature quantity meets the preset disturbance triggering condition, it is determined that there is a suspected grounding disturbance, triggering the subsequent disturbance traveling wave extraction and preprocessing process. If the feature quantity does not meet the triggering condition, it is determined that there is no grounding disturbance at present, and the device can maintain the real-time signal acquisition and monitoring state without executing the subsequent steps.

[0026] Step 103: When the ground disturbance determination result is that there is a suspected ground disturbance, the disturbance traveling wave signal is extracted from the real-time line electrical signal and preprocessed to obtain the preprocessed traveling wave signal.

[0027] In this embodiment of the invention, when the ground disturbance determination result in step 102 indicates the existence of a suspected ground disturbance, the high-resistance ground fault identification device extracts a signal segment containing the transient process of the disturbance from the real-time line electrical signal collected in step 101 based on the disturbance triggering time information, and extracts the disturbance traveling wave signal from it; then, it performs basic preprocessing on the disturbance traveling wave signal to filter out background noise and non-fault interference components, and obtains a preprocessed traveling wave signal for subsequent fault identification.

[0028] Step 104: Use preprocessed traveling wave signals to identify ground faults and obtain the ground fault identification results of the tested power distribution line.

[0029] In this embodiment of the invention, the high-resistance grounding fault identification device extracts key feature information for grounding fault identification based on the preprocessed traveling wave signal obtained in step 103, and performs matching analysis between the feature information and the preset fault identification criteria to determine whether a high-resistance grounding fault has occurred in the tested power distribution line, thereby generating the corresponding grounding fault identification result.

[0030] The power distribution line specifically refers to 10kV / 20kV medium-voltage power distribution lines, including overhead lines, cable lines, or hybrid overhead-cable lines, which are the monitoring targets of this method. The high-resistance grounding fault identification device is an external plug-in fault monitoring device that can be connected in series between the primary and secondary integrated pole-mounted circuit breaker and the feeder terminal via quick plug-in connection. It supports uninterrupted operation, and the installation and maintenance process does not require line power outage. It has the core functions of collecting line electrical signals, determining grounding disturbances, identifying high-resistance grounding faults, and recording the arrival time of traveling waves. The power distribution line under test is the target power distribution line being monitored. Primary and secondary integrated pole-mounted circuit breakers are deployed on both ends of the line, which can be adapted to single-end or double-end device deployment modes. The poles are power distribution lines. The support structure of the circuit breaker is mainly used to install the primary and secondary integrated pole-mounted circuit breaker, high-resistance grounding fault identification device, and feeder terminal, serving as the physical carrier for the device deployment. The primary and secondary integrated pole-mounted circuit breaker is a pole-mounted switching device that integrates the primary switch body and secondary voltage and current acquisition units, capable of outputting secondary voltage and current signals of the line, providing the original signal source for this device. The feeder terminal (FTU) is a distribution network automation terminal device that is matched with the primary and secondary integrated pole-mounted circuit breaker. It can collect line operation data, receive instructions from the distribution master station, and perform switch opening and closing operations. When this device is connected in series between the circuit breaker and the feeder terminal, it will transmit the signal directly without modification, without affecting the original working function of the feeder terminal. The real-time line electrical signal is the three-phase voltage and three-phase current signal of the tested distribution line output by the primary and secondary fusion pole-mounted circuit breaker. It is collected in real-time by the high-resistance ground fault identification device according to a preset sampling rate and serves as the raw data for subsequent signal analysis. Ground disturbance determination is a preliminary judgment process where the device performs power frequency and high-frequency characteristic analysis on the real-time line electrical signal to determine whether the line has experienced abnormal disturbances caused by suspected ground faults. Suspected ground disturbance refers to an abnormal state presented by the real-time line electrical signal simultaneously meeting preset power frequency and preset high-frequency judgment conditions, indicating a high probability of a ground fault in the line, requiring further extraction of traveling wave characteristics for fault identification. The disturbance traveling wave signal is the suspected ground disturbance. During the fault occurrence period, the transient traveling wave component contained in the line electrical signal is the key signal carrier reflecting the essential characteristics of the fault. The preprocessed traveling wave signal is an effective fault traveling wave signal with low noise and no reflected wave interference obtained by sequentially filtering, denoising, reflecting wave removal, and inverse wavelet transform of the disturbed traveling wave signal, providing clean feature data for ground fault identification. Ground fault identification is a process of conducting multi-dimensional feature analysis based on the preprocessed traveling wave signal to determine whether a ground fault has occurred on the line and the type of fault. The ground fault identification result is the final conclusion output by the ground fault identification process, mainly divided into three categories: no fault has occurred on the line, a low-resistance ground fault has occurred, and a high-resistance ground fault has occurred.

[0031] Please see Figure 2 , Figure 2This is a flowchart illustrating the steps of a method for identifying high-resistance grounding faults in power distribution lines, as provided in Embodiment 2 of the present invention.

[0032] It should be noted that, as Figure 3 The high-resistance grounding fault identification device shown has a single-end external mounting structure. The secondary signal output terminal of the integrated primary and secondary pole-mounted circuit breaker on one end of the tower of the distribution line under test is directly connected to the signal input terminal of the high-resistance grounding fault identification device. The signal output terminal of the high-resistance grounding fault identification device is then connected to the signal input terminal of the feeder terminal, forming a continuous secondary signal transmission link. In actual operation, the three-phase electrical signals output by the integrated primary and secondary pole-mounted circuit breaker are synchronously collected by the high-resistance grounding fault identification device for subsequent grounding disturbance judgment and fault identification analysis. On the other hand, they are directly transmitted to the feeder terminal through the device without any modification, without changing the original signal transmission logic between the equipment, and without affecting the normal operation of the original protection and monitoring functions of the distribution network. This external series installation method requires no structural modification or equipment replacement of existing primary and secondary integrated pole-mounted circuit breakers or feeder terminals. Deployment can be completed simply by on-site wiring. It effectively avoids the high costs and complex construction processes of equipment modification and complete machine replacement in traditional fault identification solutions, and realizes low-cost and non-destructive upgrade of existing distribution network equipment. At the same time, the device directly collects line electrical signals from the secondary side of the circuit breaker without the need for additional sensors. The signal acquisition link is simple and reliable, providing stable and accurate raw data support for the accurate identification of high-resistance grounding faults.

[0033] The high-resistance grounding fault identification device features an external plug-in design. It can be quickly connected in series between the primary and secondary integrated switch and the feeder terminal unit (FTU) on the tested distribution line to enable uninterrupted operation. The installation, removal, and maintenance of the device do not require power outages and do not affect the normal power supply of the distribution network. The feeder terminal unit (FTU) serves as a supporting automated terminal device for the primary and secondary integrated switch. When the device is connected in series between the primary and secondary integrated switch and the FTU, it only performs bypass acquisition and fault transient feature extraction of the secondary voltage and current signals output by the switch. The output signal is directly transmitted to the FTU without modification, completely preserving the original signal link. The FTU can continue to perform its normal functions, including real-time acquisition of line operation data, receiving control commands from the distribution master station, performing switch opening / closing operations, and local monitoring. The device measures and reports common fault information such as line short circuits and overcurrents to ensure the normal operation of the distribution network automation system. However, FTUs have a weak ability to identify high-resistance grounding faults. This device is specifically designed to analyze the transient traveling wave characteristics of high-resistance grounding faults. Its fault identification and location results can be uploaded to the distribution master station through the communication interface, complementing the fault information of the FTU and providing the master station with more comprehensive fault data, thereby improving the accuracy of fault judgment and handling. On one end of the tower of the distribution line under test, the external plug-in high-resistance grounding fault identification device can be connected in series between the primary and secondary fusion switch of the tower and the corresponding FTU. The input end of the device is connected to the three-phase voltage and three-phase current secondary signals output by the switch, and the output end is directly transmitted to the FTU. The entire process does not require line power outage. The device completes the identification of single-end high-resistance grounding faults according to the aforementioned process.

[0034] This invention provides a method for identifying high-resistance grounding faults in power distribution lines. The method is applied to a high-resistance grounding fault identification device, which is installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on one end of the tower of the power distribution line under test. The high-resistance grounding fault identification method includes: Step 201: Collect the real-time line electrical signal of the power distribution line under test.

[0035] In this embodiment of the invention, the high-resistance grounding fault identification device is connected in series between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on one end of the tower of the distribution line under test. The signal input terminal of the device is directly connected to the secondary side signal output terminal of the primary and secondary fusion pole-mounted circuit breaker, and receives and collects real-time line electrical signals such as three-phase current and three-phase voltage of the distribution line under test output by the circuit breaker in real time. At the same time, during the signal acquisition process, the device will output the real-time line electrical signal directly to the feeder terminal through the internal link without any modification, without changing the original signal transmission logic between the devices, ensuring the normal operation of the original protection and monitoring functions of the distribution network. The real-time line electrical signal collected by the device will serve as the original data basis for subsequent grounding disturbance judgment.

[0036] Step 202: Use real-time line electrical signals to determine grounding disturbances.

[0037] Furthermore, step 202 may include the following sub-steps: S11. Extract the power frequency zero-sequence component and high-frequency transient component of the real-time line electrical signal.

[0038] In this embodiment of the invention, the device first performs phasor summation calculation on the acquired three-phase voltage and three-phase current signals to obtain the initial zero-sequence voltage and zero-sequence current signals. Then, it filters the initial zero-sequence signal through a built-in power frequency bandpass filter to separate the power frequency zero-sequence voltage and power frequency zero-sequence current, i.e., the power frequency zero-sequence components. At the same time, the device performs high-frequency transient feature separation on the real-time line electrical signal through a built-in high-pass filter, filters out the steady-state components at and below the power frequency, and extracts the high-frequency transient components containing fault transient information, thus completing the extraction of the two key components.

[0039] S12. Determine whether the power frequency zero-sequence component meets the preset power frequency judgment condition, and determine whether the high-frequency transient component meets the preset high-frequency judgment condition.

[0040] The power frequency zero-sequence component includes power frequency zero-sequence voltage and power frequency zero-sequence current. The preset power frequency judgment condition is that the power frequency zero-sequence voltage exceeds the preset normal voltage fluctuation range and the power frequency zero-sequence current is lower than the preset current threshold. The preset high-frequency judgment condition is that there is a sudden change in the amplitude of the high-frequency transient component, and the amplitude of the change is higher than the preset environmental high-frequency noise amplitude threshold.

[0041] In this embodiment of the invention, the device then judges the extracted power frequency zero-sequence component and high-frequency transient component according to preset conditions. The device internally stores preset power frequency judgment conditions and preset high-frequency judgment conditions set according to the normal operation conditions of the distribution network and the characteristics of high-resistance grounding faults. The preset power frequency judgment condition is that the power frequency zero-sequence voltage exceeds the preset normal voltage fluctuation range and the power frequency zero-sequence current is lower than the preset current threshold. The preset high-frequency judgment condition is that the high-frequency transient component has an amplitude change and the change amplitude is higher than the preset environmental high-frequency noise amplitude threshold. The device compares the real-time extracted power frequency zero-sequence voltage with the preset normal voltage fluctuation range and compares the power frequency zero-sequence current with the preset current threshold to confirm whether the power frequency judgment conditions of voltage exceeding the limit and current being lower than the threshold are met simultaneously. At the same time, the device monitors the extracted high-frequency transient component in real time, and judges whether there is an amplitude change by calculating the instantaneous rate of change and amplitude change of the signal. The change amplitude is compared with the preset environmental high-frequency noise amplitude threshold to confirm whether the high-frequency judgment condition is met.

[0042] S13. If the preset power frequency judgment condition or the preset high frequency judgment condition is not met, it is determined that there is no suspected grounding disturbance in the tested power distribution line, and this is taken as the grounding disturbance judgment result.

[0043] In this embodiment of the invention, when the device determines that the preset power frequency determination condition or the preset high frequency determination condition is not met, or neither is met, it indicates that the signal characteristics of the current line do not match the typical characteristics of a high-resistance grounding fault. It may be due to signal fluctuations caused by normal unbalanced loads, external interference, or other non-fault disturbances. At this time, the device determines that there is no suspected grounding disturbance in the tested power distribution line and takes this result as the grounding disturbance determination result. The device maintains normal signal acquisition and monitoring status, does not trigger the subsequent traveling wave extraction and preprocessing process, and continues to continuously monitor the real-time line electrical signal of the tested power distribution line.

[0044] S14. When both the preset power frequency judgment condition and the preset high frequency judgment condition are met simultaneously, the tested power distribution line is judged to have a suspected grounding disturbance, and this is taken as the grounding disturbance judgment result.

[0045] In this embodiment of the invention, when the device determines that both the preset power frequency determination condition and the preset high frequency determination condition are met simultaneously, it indicates that the current line has simultaneously experienced a power frequency steady-state anomaly and a high frequency transient change that conform to the characteristics of a high-resistance grounding fault, thus ruling out the possibility of a single interference or non-fault disturbance. Based on this, the device determines that the tested power distribution line has a suspected grounding disturbance and uses this result as the grounding disturbance determination result, triggering the subsequent disturbance traveling wave extraction and preprocessing process, providing a reliable preliminary judgment basis for the subsequent grounding fault identification steps.

[0046] The power frequency zero-sequence component refers to the 50Hz power frequency zero-sequence voltage and zero-sequence current components in the real-time line electrical signal. It reflects the steady-state three-phase imbalance characteristics of the line and serves as the power frequency basis for grounding disturbance judgment. The high-frequency transient component refers to the transient change component in the real-time line electrical signal generated by the fault and with a frequency higher than the power frequency. It reflects the transient characteristics at the moment the fault occurs and serves as the high-frequency basis for grounding disturbance judgment. The preset power frequency judgment condition is an anomaly judgment rule set for the power frequency zero-sequence component. It conforms to the typical characteristics of high-resistance grounding faults, such as zero-sequence voltage deviation and low zero-sequence current amplitude, and realizes grounding disturbance judgment from the steady-state level. The preset high-frequency judgment condition is an anomaly judgment rule set for the high-frequency transient component. It is used to distinguish between fault transient changes and non-fault-related high-frequency fluctuations such as environmental noise and equipment interference, and realizes grounding disturbance judgment from the transient level.

[0047] The power frequency zero-sequence voltage is the zero-sequence component synthesized from the three-phase voltages. It directly reflects the degree of three-phase voltage imbalance. When a high-resistance ground fault occurs in a distribution line, the system's voltage imbalance to ground increases significantly, and the power frequency zero-sequence voltage will show a significant shift, making it a core indicator for power frequency identification. The power frequency zero-sequence current is the zero-sequence component synthesized from the three-phase currents. Due to the larger ground impedance in a high-resistance ground fault, the corresponding zero-sequence current amplitude is much lower than that in a low-resistance ground fault, making it a key indicator for distinguishing between high-resistance and low-resistance ground faults. The preset normal voltage fluctuation range is the allowable fluctuation range of the power frequency zero-sequence voltage under normal operating conditions of the distribution line. The range is set based on parameters such as the line's rated voltage and the system's inherent imbalance. When the power frequency zero-sequence voltage exceeds this range, it is determined that the line has a grounding abnormality. The preset current threshold is a zero-sequence current judgment threshold set for the characteristics of high-resistance grounding faults. If the zero-sequence current is lower than this threshold, it can effectively eliminate interference caused by low-resistance grounding faults and complete the initial screening of high-resistance faults. The preset environmental high-frequency noise amplitude threshold is the maximum allowable amplitude of high-frequency signals generated by factors such as equipment electromagnetic interference and external environmental noise during normal line operation. Only when the sudden amplitude of high-frequency transient components exceeds this threshold will it be identified as a valid transient disturbance, thereby eliminating conventional noise interference.

[0048] Step 203: When the ground disturbance determination result is that there is a suspected ground disturbance, the disturbance traveling wave signal during the disturbance period is extracted from the real-time line electrical signal and filtered to obtain the filtered traveling wave signal.

[0049] In this embodiment of the invention, after the device determines that there is a suspected grounding disturbance in the tested power distribution line, the device immediately uses the moment of amplitude change of the high-frequency transient component in step 202 as a reference to locate the starting time of the disturbance. Following a preset time window, for example, centered on the moment of change, it traces back several milliseconds and extends forward tens of milliseconds to extract a continuous three-phase electrical signal segment containing the entire transient process of the disturbance from the real-time line electrical signal acquired and cached in step 201. This segment completely covers the signal change process before and after the fault, ensuring that complete fault transient features can be extracted. Subsequently, the device performs power frequency steady-state component separation on the extracted signal segment, filtering out the power frequency voltage and current components to extract the disturbance traveling wave signal containing only fault transient information. Considering the complex operating environment of the field line, the extracted disturbance traveling wave signal may be mixed with non-fault high-frequency interference such as line coupling noise and environmental electromagnetic interference. The device further performs targeted filtering on the disturbance traveling wave signal to filter out noise components unrelated to the fault characteristics, effectively improving the signal-to-noise ratio, and finally obtaining a clean and stable filtered traveling wave signal.

[0050] Step 204: Denoise the filtered traveling wave signal to obtain a denoised traveling wave signal.

[0051] In this embodiment of the invention, the device first performs noise reduction processing. For the signal characteristics of a 10kV distribution line scenario, a preset FIR bandpass filter is used to filter the traveling wave signal by frequency band selection. The passband is set to 5kHz~50kHz to ensure that the useful frequency band (1kHz~100kHz) of the traveling wave signal is preserved, while effectively suppressing odd harmonics and high-frequency sampling noise in the line. Based on this, the device further employs wavelet thresholding to decompose the bandpass-filtered signal using wavelets and remove background noise. By dynamically generating a threshold through the calculation of the noise standard deviation, noise components below the threshold are suppressed, resulting in a noise-reduced traveling wave signal with a significantly improved signal-to-noise ratio.

[0052] Step 205: According to the preset number of decomposition layers, perform discrete wavelet decomposition on the denoised traveling wave signal to obtain the layered wavelet coefficient set.

[0053] In this embodiment of the invention, the device selects a compactly supported, approximately symmetric, and regularly regularized db4 / db6 or sym8 wavelet according to a preset number of decomposition layers (6-8 layers) to perform discrete wavelet decomposition on the denoised traveling wave signal obtained in step 204, splitting the signal into wavelet coefficients of different frequency bands to achieve local time-frequency separation. The approximate coefficients obtained by decomposition correspond to the traveling wave fundamental wave in the low-frequency band, and the detail coefficients correspond to the traveling wave abrupt component in the high-frequency band, thereby obtaining a hierarchical wavelet coefficient set containing coefficient information at each scale, and completing the structured decomposition of the signal at different scales and frequencies.

[0054] Step 206: Extract effective high-frequency detail coefficients from the layered wavelet coefficient set to obtain the effective high-frequency detail coefficient sequence.

[0055] In this embodiment of the invention, the device filters and extracts high-frequency detail coefficients from the layered wavelet coefficient set obtained in step 205 according to the preset extraction frequency band. These coefficients correspond to the core frequency band of the fault traveling wave mutation and can accurately reflect the key mutation information in the fault transient process. Low-frequency approximation coefficients that are irrelevant to the fault characteristics and high-frequency detail coefficients in non-core frequency bands are removed to form an effective high-frequency detail coefficient sequence, which further focuses on the effective feature information of the fault traveling wave.

[0056] Step 207: Detect traveling wave abrupt change feature points from the effective high-frequency detail coefficient sequence and extract the corresponding effective high-frequency detail coefficients.

[0057] In this embodiment of the invention, the device performs step 207, detecting abrupt change feature points of the traveling wave from the effective high-frequency detail coefficient sequence and extracting the corresponding effective high-frequency detail coefficients. Since the abrupt change feature points of the fault traveling wave in the effective high-frequency detail coefficient sequence will manifest as local maxima (i.e., modulus maxima) of the absolute values ​​of the coefficients, the device locates the abrupt change time of the fault traveling wave by detecting these modulus maxima points. Specifically, the device first traverses the effective high-frequency detail coefficient sequence obtained in step 206, and extracts the effective high-frequency detail coefficients corresponding to each time n in the sequence. Simultaneously, three judgments are made: First, whether the absolute value of the effective high-frequency detail coefficients at that moment is simultaneously greater than the absolute values ​​of the coefficients at the adjacent previous and next moments, i.e. and The second step is to determine whether the absolute value of the coefficient is greater than a preset threshold, which is 3 to 5 times the noise standard deviation calculated in step 204 of the noise reduction process. This threshold can effectively distinguish between real fault abrupt changes and random noise fluctuations. The third step is to determine whether the coefficient changes of multiple consecutive sampling points before and after the given moment show the same upward or downward trend, thus eliminating irregular single-point abnormal fluctuation interference. When the effective high-frequency detail coefficients at a certain moment simultaneously meet the above three judgment conditions, the device determines that moment as a traveling wave abrupt change feature point, records the time position of the feature point, and extracts the effective high-frequency detail coefficients corresponding to that position. After traversal, the device organizes all detected abrupt change feature points and their corresponding effective high-frequency detail coefficients into a feature point sequence, which includes both the modulus maxima corresponding to the initial traveling wave of the fault and the modulus maxima corresponding to the line reflected wave.

[0058] Step 208: Remove the reflected wave from the effective high-frequency detail coefficients corresponding to each mutation feature point, and perform discrete wavelet inverse transform to obtain the preprocessed traveling wave signal.

[0059] In this embodiment of the invention, the device first sorts all the abrupt change feature points obtained in step 207 in ascending order according to their arrival time, generating a time-sorted feature point list. Each list item contains two pieces of information: the arrival time of the feature point and the corresponding effective high-frequency detail coefficient amplitude. Then, the device locks onto the target feature point corresponding to the initial incident wave of the fault: since the initial traveling wave of the fault is the first transient component to arrive at the device and has not undergone line propagation attenuation, its amplitude is the largest among all feature points. The device selects the feature point with the earliest arrival time from the sorted list and verifies that the effective high-frequency detail coefficient amplitude corresponding to this point is the largest among all feature points, thus confirming that this point is the first arrival point of the initial incident wave of the fault, and as the only valid feature point retained in the single-ended scenario, its corresponding effective high-frequency detail coefficient is the target coefficient.

[0060] Next, the device performs reflection wave judgment and elimination processing on all other feature points in the list, adapting to single-end installation scenarios. The device is based on the known length of the power distribution line under test (i.e., the preset main length of the power distribution line under test) and the preset traveling wave velocity (i.e., the propagation speed of the traveling wave in the line, such as approximately 2.7 × 10⁻⁶ for overhead lines). 8 m / s, for cable lines approximately 1.8 × 10 m / s 8 The theoretical arrival time window for the reflected wave from the opposite busbar is calculated using the speed of the traveling wave (m / s). The traveling wave emitted from the fault point propagates towards the opposite end of the line, is reflected upon reaching the busbar, and then returns to the device. The theoretical propagation time difference is 2L / v (where L is the length of the main trunk of the tested distribution line, and v is the speed of the traveling wave). The device uses the arrival time of the initial incident wave as a reference and sets the time interval corresponding to this time difference as the reflected wave determination window. Simultaneously, considering the attenuation characteristics of traveling wave propagation, the amplitude of the reflected wave will be significantly lower than the amplitude of the initial incident wave after long-distance propagation and reflection. The device uses this characteristic as an auxiliary determination condition. For feature points in the sorted list whose arrival time falls within the reflected wave determination window and whose effective high-frequency detail coefficient amplitude is significantly lower than the initial incident wave amplitude, the device directly determines them as feature points corresponding to the line reflected wave, discarding these points and their corresponding effective high-frequency detail coefficients to avoid interference from the reflected wave components in subsequent fault identification.

[0061] After eliminating reflected waves, the device retains only the effective high-frequency detail coefficients corresponding to the initial incident wave of the fault. These coefficients are then combined with the low-frequency approximation coefficients obtained from the discrete wavelet decomposition in step 205. An inverse discrete wavelet transform is performed using the same wavelet basis (such as db4 / db6 or sym8 wavelets) as the decomposition process to reconstruct a preprocessed traveling wave signal free from reflected wave interference and with effectively suppressed noise. This signal retains only the core transient characteristics of the initial incident wave of the fault, making it perfectly suited for signal acquisition scenarios with single-ended external installations.

[0062] Filtering involves bandpass processing of the extracted disturbance traveling wave signal to remove unwanted signal components such as power frequency harmonics and line carrier interference, thus obtaining a filtered traveling wave signal. Noise reduction is the process of adaptively denoising the filtered traveling wave signal to eliminate random interference such as environmental noise and equipment white noise, improving the signal-to-noise ratio and obtaining a denoised traveling wave signal. Discrete wavelet decomposition is a signal processing method that uses discrete wavelet transform to break down the denoised traveling wave signal into different frequency bands to form a hierarchical wavelet coefficient set, effectively separating the high-frequency detail components and low-frequency approximation components of the fault traveling wave. The hierarchical wavelet coefficient set is the complete set of wavelet coefficients obtained at different decomposition levels after discrete wavelet decomposition of the denoised traveling wave signal, including two main types: low-frequency approximation coefficients and high-frequency detail coefficients. Effective high-frequency detail coefficients are selected from the hierarchical wavelet coefficient set and reflect the fault traveling wave. The process involves identifying high-frequency detail coefficients that represent wave mutation characteristics, while simultaneously removing invalid coefficients that lack mutation features. The effective high-frequency detail coefficient sequence is a set of coefficients arranged chronologically, used for detecting traveling wave mutation feature points. A traveling wave mutation feature point is the corresponding time point in the effective high-frequency detail coefficient sequence where the amplitude mutation exceeds a set threshold; this time corresponds to the arrival time of the initial traveling wave at the device. Reflection wave elimination involves analyzing and identifying the effective high-frequency detail coefficients corresponding to the traveling wave mutation feature point, removing coefficients corresponding to reflected waves generated by impedance discontinuities such as line branches and joints, retaining only the effective coefficients of the initial traveling wave at the fault, thus avoiding interference from reflected waves in subsequent signal analysis. Discrete wavelet inverse transform is the process of reconstructing the traveling wave signal and ultimately obtaining the pre-processed traveling wave signal based on the effective high-frequency detail coefficients after removing reflected waves.

[0063] Step 209: Use preprocessed traveling wave signals to identify ground faults and obtain the ground fault identification results of the tested power distribution line.

[0064] Furthermore, step 209 may include the following sub-steps: S21. Perform variational mode decomposition on the preprocessed traveling wave signal to obtain multiple sets of intrinsic mode components.

[0065] In this embodiment of the invention, the device performs variational mode decomposition on the preprocessed traveling wave signal obtained by reconstruction in step 208, overcoming the mode aliasing problem of traditional signal decomposition. It adaptively decomposes the preprocessed traveling wave signal into multiple sets of intrinsic mode components with non-overlapping frequency bands. Each intrinsic mode component corresponds to an independent characteristic frequency band, which can effectively separate the weak transient characteristics of high-impedance grounding faults from the residual steady-state baseline components, completely preserve the key information of the fault signal, and obtain multiple sets of hierarchical and feature-independent intrinsic mode components.

[0066] S22. Perform wavelet packet energy spectrum analysis on the intrinsic mode components of each group, and extract multi-dimensional fault quantification indicators from the analysis results.

[0067] In this embodiment of the invention, wavelet packet energy spectrum analysis is performed on each set of intrinsic mode components obtained by S21 decomposition. The time-frequency domain depth analysis of each set of intrinsic mode components is performed by preset wavelet packet decomposition parameters to calculate the energy proportion of each frequency band, comprehensively capture the energy distribution characteristics and frequency domain variation law of the fault signal, and extract multi-dimensional fault quantification indicators including energy characteristics, frequency domain characteristics, and fluctuation characteristics based on the analysis results to construct a complete set of multi-dimensional fault quantification indicators.

[0068] S23. Calculate the kurtosis value of each group of intrinsic mode components, and extract effective fault quantification indicators from the multi-dimensional fault quantification indicators based on the kurtosis value.

[0069] In this embodiment of the invention, the device calculates the corresponding kurtosis value for each set of intrinsic mode components obtained in S21. The kurtosis value can reflect the pulse characteristics of the signal. As a pulse signal, the fault traveling wave has a kurtosis value of its corresponding intrinsic mode component that is significantly higher than that of the components corresponding to stable interference signals such as load fluctuations and electromagnetic clutter. The formula for calculating kurtosis is as follows:

[0070] In the formula, This is the kurtosis value. For mathematical expectation, The sampled signal of the current intrinsic mode components, The mean of the signal. This represents the standard deviation of the signal.

[0071] The device performs hierarchical processing on the multi-dimensional fault quantification indicators extracted by S22 based on the kurtosis values ​​of each set of intrinsic mode components: when the kurtosis value of an intrinsic mode component is greater than 3, the component is determined to be a fault characteristic component, and all corresponding multi-dimensional fault quantification indicators are retained; when the kurtosis value of an intrinsic mode component is between 1 and 3, the component is determined to be a weak interference component, and its corresponding multi-dimensional fault quantification indicators are subjected to soft threshold attenuation processing, retaining 50% of the energy weight to weaken the influence of the interference component on subsequent analysis; when the kurtosis value of an intrinsic mode component is less than 1, the component is determined to be a pure interference component, and all corresponding multi-dimensional fault quantification indicators are removed. After the above screening and processing, the device removes invalid indicators corresponding to pure interference components from the set of multi-dimensional fault quantification indicators obtained by S22, weakens the influence of weak interference components, and retains only the effective fault quantification indicators that can truly reflect the characteristics of grounding faults, thus completing the dynamic suppression of interference signals.

[0072] S24. Normalize the effective fault quantification indicators and construct a standardized fault feature vector by combining them with preset weights.

[0073] In this embodiment of the invention, the device performs global normalization on the effective fault quantification indicators obtained by screening in S23, eliminating the dimensional differences and numerical magnitude deviations between indicators of different dimensions, and uniformly mapping all indicators to a standard numerical range; then, combined with the pre-trained and calibrated preset weights, the normalized effective fault quantification indicators are weighted and fused, giving higher weights to core indicators with high fault identification sensitivity and lower weights to auxiliary indicators, thereby strengthening the core fault features and weakening invalid interference features, and finally constructing a standardized fault feature vector with unified dimensions and focused features.

[0074] S25. Match the standardized fault feature vector with the preset fault sample library, determine the ground fault type based on the matching result, and use it as the ground fault identification result.

[0075] In this embodiment of the invention, the device performs full-domain feature matching between the standardized fault feature vector constructed in S24 and the preset fault sample library stored locally in the device. The preset fault sample library contains standard fault feature samples corresponding to different operating conditions. The device completes the sample comparison and matching through a feature similarity algorithm, determines the ground fault type of the current tested power distribution line based on the optimal matching result, distinguishes between real ground faults and non-fault disturbances, and uses the determination result as the final ground fault identification result.

[0076] Variational Mode Decomposition (VMD) is an adaptive signal decomposition method that decomposes a preprocessed traveling wave signal into multiple sets of intrinsic mode components (EMCs) with different center frequencies. It effectively separates fault features from noise components and is suitable for the weak transient characteristics of high-impedance grounding faults. EMCs are narrowband mode components obtained after variational VMD of the preprocessed traveling wave signal; each component corresponds to an independent center frequency and carries fault feature information in different frequency bands. Wavelet packet energy spectrum analysis (WPA) is an analytical method that performs wavelet packet decomposition on the EMCs, calculates the energy distribution of each frequency band, and extracts signal energy features, enabling a quantitative characterization of energy changes caused by faults. Multidimensional fault quantification indicators are a set of parameters extracted from the wavelet packet energy spectrum analysis results, covering energy entropy, energy proportion of each frequency band, kurtosis, etc., used to comprehensively describe fault characteristics. Kurtosis is a statistical indicator describing the steepness of the signal distribution; the kurtosis value of the EMCs corresponding to high-impedance grounding faults is significantly higher than that of normal noise components, mainly used to screen effective fault feature components. Effective fault quantification indicators are selected based on the kurtosis values ​​of each EMC. The system retains multi-dimensional quantitative indicators containing real fault characteristics while eliminating invalid indicators corresponding to noise components. Normalization involves standardizing the effective fault quantitative indicators to eliminate dimensional differences between different indicators, unifying them into the same numerical range to facilitate subsequent feature vector construction. Preset weights are weight coefficients pre-defined based on the sensitivity of different fault quantitative indicators to high-resistance grounding faults, used to construct standardized fault feature vectors. Standardized fault feature vectors are vectors formed by combining normalized effective fault quantitative indicators with preset weights; they represent a standardized expression of fault characteristics and are used for matching and identification with a fault sample library. The preset fault sample library is a database storing standardized fault feature vector samples corresponding to various operating states, such as normal line operation, low-resistance grounding faults, and high-resistance grounding faults with different grounding impedances, providing a reference for fault type matching. Fault types are classifications of line operating states, mainly including categories such as normal operation, low-resistance grounding faults, and high-resistance grounding faults; these are also the specific output content of the grounding fault identification results.

[0077] In one optional embodiment, please refer to Figure 4As shown, both ends of the tested distribution line are equipped with primary and secondary integrated pole-mounted circuit breakers. A high-resistance grounding fault identification device is externally installed between the secondary side of each circuit breaker and the corresponding feeder terminal unit (FTU), forming a dual-end synchronous acquisition deployment architecture. The input end of each high-resistance grounding fault identification device is connected to the three-phase voltage and three-phase current secondary signals output from the corresponding primary and secondary integrated pole-mounted circuit breaker. The output end transmits the signals directly to the corresponding feeder terminal without modification, without altering the original signal transmission link between the devices, ensuring the normal operation of the original protection and monitoring functions of the distribution network. In the dual-end deployment mode, the two devices can synchronously acquire and analyze the electrical signals at both ends of the tested distribution line, providing data support for accurate identification and location of high-resistance grounding faults by combining the transient characteristics of faults at both ends.

[0078] Furthermore, an external plug-in high-resistance grounding fault identification device is also installed between the primary and secondary fusion switch and the corresponding feeder terminal unit (FTU) on the other end of the tested distribution line. Both devices are connected via quick plug-in, without any power outage. The input terminals of the two devices are respectively connected to the three-phase voltage and three-phase current secondary signals output by the corresponding primary and secondary fusion switch. The output terminals transmit the signals directly to the corresponding FTU without modification, without changing the original equipment's operating logic and signal link, thus forming a dual-end synchronous acquisition deployment architecture. When a high-resistance grounding fault is identified at one end, the two devices can synchronously read the arrival time of the fault traveling wave and accurately locate the fault point based on the formulas encapsulated in steps A4-A7.

[0079] Furthermore, another high-resistance grounding fault identification device is installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on the other end of the tower of the tested distribution line. When the grounding fault identification result indicates that there is a high-resistance grounding fault in the tested distribution line, the following steps may also be included: A1. Read the absolute arrival time of the first fault traveling wave recorded in the high-resistance grounding fault identification device; In this embodiment of the invention, the first fault traveling wave is the same signal as the fault transient traveling wave extracted after step 102 of the aforementioned single-end operation process, which determines a suspected grounding disturbance. The traveling wave extraction logic of the single end is completely adopted: when the device determines that there is a suspected grounding disturbance, it will extract transient traveling wave features from the real-time line electrical signal collected in step 101 and identify the starting point of the fault initial traveling wave. The high-precision timing module (such as the Beidou / GPS timing unit) built into the device synchronously records the time corresponding to the sudden change point, generates the arrival absolute time of the first fault traveling wave with a timestamp, and stores the timestamp and the fault traveling wave features together in the local storage module of the device for subsequent positioning process reading.

[0080] A2. Read the absolute arrival time of the second fault traveling wave recorded in another high-resistance grounding fault identification device; In this embodiment of the invention, another high-resistance grounding fault identification device operates with the same logic as the device at one end of the tested power distribution line: it synchronously acquires the three-phase voltage and current signals at the other end of the line, executes the same grounding disturbance judgment and fault traveling wave extraction process, identifies the starting abrupt change point of the initial fault traveling wave, and synchronously marks this moment through its built-in high-precision time synchronization module, generating the absolute arrival time of the second fault traveling wave, which is also stored in the local storage module. This second fault traveling wave is of the same type as the fault traveling wave extracted in the single-end process; both are initial transient traveling waves generated by the fault point, only the arriving version at the other end of the line. Its extraction rules and judgment criteria are completely consistent with the aforementioned single-end process.

[0081] A3. Based on the line type of the power distribution line under test, retrieve the preset line traveling wave propagation velocity table and match the corresponding line traveling wave propagation velocity; In this embodiment of the invention, the storage module of the device has a preset traveling wave propagation speed table, which stores the traveling wave propagation speeds corresponding to different types of power distribution lines, for example: The traveling wave propagation speed of overhead power lines is approximately 0.95 to 0.99 times the speed of light (approximately 2.85 × 10⁸ to 2.97 × 10⁸ m / s). The traveling wave propagation speed of cable lines is approximately 0.6 to 0.8 times the speed of light (approximately 1.8 × 10⁸ / 2.4 × 10⁸ m / s).

[0082] The device retrieves and matches the corresponding traveling wave propagation speed of the power distribution line under test (such as the user-preset "overhead line", "cable line" or the line type automatically identified by the system) from the table, with the unit being m / s.

[0083] A4. The target difference is obtained by calculating the difference between the absolute arrival times of the first fault traveling wave and the second fault traveling wave. A5. The target multiplication value is obtained by multiplying the target difference with the line traveling wave propagation speed; A6. The target sum is obtained by performing a summation operation using the target multiplier and the preset length of the main trunk of the power distribution line under test. A7. The distance from the fault point to the high-resistance grounding fault identification device is obtained by calculating the ratio between the target sum and the line geometric correction coefficient.

[0084] In this embodiment of the invention, for ease of understanding, the above steps A4-A7 are encapsulated in the form of formulas: ; In the formula, This refers to the distance from the fault point to the high-resistance grounding fault identification device, i.e., the fault location distance. The preset length of the main branch of the power distribution line under test is a known fixed parameter preset by the system. The absolute time of arrival of the first fault traveling wave. For the absolute time of arrival of the traveling wave of the second fault, For the traveling wave propagation speed of the line, The line geometric correction coefficient is a dimensionless theoretical constant derived from the symmetrical deployment of the devices at both ends of the tested line and the bidirectional propagation characteristics of the fault traveling wave. Its value is always 2.

[0085] Another high-resistance grounding fault identification device is installed on the tower at the other end of the tested distribution line. It can synchronously collect line electrical signals with the device at one end to complete the dual-end traveling wave fault location. High-resistance grounding faults are distribution line grounding faults where the grounding impedance is greater than a preset threshold. This type of fault has a small fault current amplitude, making it difficult for conventional overcurrent protection to identify. It is the key fault type identified in this solution. The absolute time of arrival of the first fault traveling wave is the time when the initial traveling wave of the fault arrives at the device, recorded by the high-resistance grounding fault identification device at one end of the tested distribution line through a built-in GPS / BeiDou dual-mode synchronous clock. It is an absolute time value with a precise timestamp. The absolute arrival time of the second fault traveling wave is the time when the initial traveling wave of the fault arrives at another high-resistance grounding fault identification device at the other end of the tested distribution line, recorded by a built-in GPS / BeiDou dual-mode synchronous clock. This is an absolute time value with a precise timestamp. The preset line traveling wave propagation velocity table is a lookup table pre-stored within the device. This table includes traveling wave propagation velocity parameters corresponding to different types of distribution lines, such as overhead lines, cables, and mixed lines, used to automatically match the wave velocity according to the line type. The line traveling wave propagation velocity is obtained by matching the actual type of the tested distribution line from the preset line traveling wave propagation velocity table, representing the transient travel wave of the fault. The speed of wave propagation in the line medium is the core calculation parameter for double-ended fault location; the target difference is the result obtained by calculating the difference between the absolute arrival times of the first and second fault traveling waves, reflecting the time difference between the arrival times of the fault traveling waves at both ends of the line; the target multiplier is the result of multiplying the target difference by the propagation speed of the traveling waves, representing the difference in the propagation path of the fault traveling waves to the two ends of the line, reflecting the offset distance of the fault point relative to the midpoint of the line; the preset length of the main trunk of the distribution line under test is the total length of the line between the towers at both ends of the distribution line under test, which is a fixed known parameter pre-entered into the device; the target and The value is the result of adding the preset length of the main trunk of the distribution line under test to the target value. Its physical meaning is twice the distance from the fault point to the single-end high-resistance grounding fault identification device. The line geometric correction coefficient is a dimensionless theoretical constant derived from the physical model of double-end traveling wave positioning. Its value is always 2. Its function is to convert the target and the value into the actual distance from the fault point to the device. It is the core correction parameter in the positioning formula. The distance from the fault point to the high-resistance grounding fault identification device is the final calculation result of the entire double-end traveling wave positioning process. It represents the straight-line distance from the fault location to the high-resistance grounding fault identification device on one end of the tower, thereby achieving accurate fault point positioning.

[0086] Please see Figure 5 , Figure 5 This is a structural block diagram of a high-resistance grounding fault identification device for power distribution lines, provided in Embodiment 3 of the present invention.

[0087] This invention provides a high-resistance grounding fault identification device for power distribution lines. The device is installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on one end of the power distribution line under test. The high-resistance grounding fault identification device includes: The wideband current transformer 501 is used to acquire the real-time line electrical signal of the power distribution line under test. The suspected disturbance detection module 502 is used to determine ground disturbances using real-time line electrical signals. The traveling wave preprocessing module 503 is used to extract the disturbance traveling wave signal from the real-time line electrical signal and perform preprocessing to obtain the preprocessed traveling wave signal when the ground disturbance determination result is that there is a suspected ground disturbance. The fault identification and judgment module 504 is used to identify ground faults using preprocessed traveling wave signals and obtain the ground fault identification results of the tested power distribution line.

[0088] Since the above is a device corresponding to a method for identifying high-resistance grounding faults in power distribution lines, and its implementation principle is the same as that of a method for identifying high-resistance grounding faults in power distribution lines, for the sake of convenience and brevity, those skilled in the art can clearly understand that the specific working process of the device and module described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0089] Please see Figure 6 , Figure 6 This is a structural block diagram of an electronic device provided in Embodiment 4 of the present invention.

[0090] An electronic device according to an embodiment of the present invention includes a memory 601 and a processor 602. The memory 601 stores a computer program. When the computer program is executed by the processor 602, the processor 602 performs the high-resistance grounding fault identification method for power distribution lines as described in the above embodiment.

[0091] Memory 601 may be an electronic memory such as flash memory, EEPROM (Electrically Erasable Programmable Read-Only Memory), EPROM, hard disk, or ROM. Memory 601 has storage space 603 for program code 613 for performing any of the method steps described above. For example, storage space 603 for program code may include various program codes 613 for implementing the various steps in the methods described above. This program code may be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, CDs, memory cards, or floppy disks. The program code may be compressed, for example, in a suitable form. When run by a computing processing device, this code causes the computing processing device to perform the various steps in the methods described above. This program code may be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, CDs, memory cards, or floppy disks. The program code may be compressed, for example, in a suitable form. When these codes are run by a computing processing device, the computing processing device causes the device to perform the various steps in the high-resistance grounding fault identification method for power distribution lines described above.

[0092] Embodiment 5 of the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the high-resistance grounding fault identification method for power distribution lines as described in the above embodiments.

[0093] Embodiment 6 of the present invention also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions, wherein when the program instructions are executed by a computer, the computer performs the high-resistance grounding fault identification method for power distribution lines as described in the above embodiments.

[0094] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0095] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between apparatuses or units, and may be electrical, mechanical, or other forms.

[0096] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0097] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0098] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0099] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for identifying high-resistance grounding faults in power distribution lines, characterized in that, A high-resistance grounding fault identification device is used in a high-resistance grounding fault identification device. The device is installed between the primary and secondary integrated pole-mounted circuit breaker and the feeder terminal on one end of a tower of the tested power distribution line. The high-resistance grounding fault identification method includes: Collect the real-time line electrical signal of the power distribution line under test; The grounding disturbance is determined using the real-time line electrical signal. When the ground disturbance determination result is that there is a suspected ground disturbance, the disturbance traveling wave signal is extracted from the real-time line electrical signal and preprocessed to obtain the preprocessed traveling wave signal. The ground fault identification result of the tested power distribution line is obtained by using the preprocessed traveling wave signal for ground fault identification.

2. The method for identifying high-resistance grounding faults in power distribution lines according to claim 1, characterized in that, The method of using the real-time line electrical signal to determine grounding disturbances includes: Extract the power frequency zero-sequence component and high-frequency transient component of the real-time line electrical signal; Determine whether the power frequency zero-sequence component meets the preset power frequency determination condition, and determine whether the high-frequency transient component meets the preset high-frequency determination condition; If the preset power frequency determination condition or the preset high frequency determination condition is not met, it is determined that there is no suspected grounding disturbance in the tested power distribution line, and this is taken as the grounding disturbance determination result. When both the preset power frequency determination condition and the preset high frequency determination condition are met simultaneously, the tested power distribution line is determined to have a suspected grounding disturbance, and this is taken as the grounding disturbance determination result.

3. The method for identifying high-resistance grounding faults in power distribution lines according to claim 2, characterized in that, The power frequency zero-sequence component includes power frequency zero-sequence voltage and power frequency zero-sequence current. The preset power frequency determination condition is that the power frequency zero-sequence voltage exceeds the preset normal voltage fluctuation range and the power frequency zero-sequence current is lower than the preset current threshold. The preset high-frequency determination condition is specifically that the high-frequency transient component has an amplitude change, and the amplitude of the change is higher than the preset environmental high-frequency noise amplitude threshold.

4. The method for identifying high-resistance grounding faults in power distribution lines according to claim 1, characterized in that, When the ground disturbance determination result indicates the existence of a suspected ground disturbance, the disturbance traveling wave signal is extracted from the real-time line electrical signal and preprocessed to obtain a preprocessed traveling wave signal, including: When the ground disturbance determination result is that there is a suspected ground disturbance, the disturbance traveling wave signal during the disturbance occurrence period is extracted from the real-time line electrical signal and filtered to obtain the filtered traveling wave signal. The filtered traveling wave signal is denoised to obtain a denoised traveling wave signal; According to the preset number of decomposition layers, the noise-reduced traveling wave signal is subjected to discrete wavelet decomposition to obtain a set of layered wavelet coefficients; Effective high-frequency detail coefficients are extracted from the hierarchical wavelet coefficient set to obtain an effective high-frequency detail coefficient sequence; Detect traveling wave abrupt change feature points from the effective high-frequency detail coefficient sequence and extract the corresponding effective high-frequency detail coefficients; The effective high-frequency detail coefficients corresponding to each of the abrupt feature points are removed by reflection wave elimination, and then a discrete wavelet inverse transform is performed to obtain a preprocessed traveling wave signal.

5. The method for identifying high-resistance grounding faults in power distribution lines according to claim 1, characterized in that, The method of using the preprocessed traveling wave signal for ground fault identification to obtain the ground fault identification result of the tested power distribution line includes: The preprocessed traveling wave signal is subjected to variational mode decomposition to obtain multiple sets of intrinsic mode components; Wavelet packet energy spectrum analysis was performed on the intrinsic mode components of each group, and multi-dimensional fault quantification indicators were extracted from the analysis results. Calculate the kurtosis value of each group of intrinsic mode components, and extract effective fault quantification indicators from the multi-dimensional fault quantification indicators based on the kurtosis value; The effective fault quantification index is normalized and combined with preset weights to construct a standardized fault feature vector. The standardized fault feature vector is matched with a preset fault sample library, and the ground fault type is determined based on the matching result, which is then used as the ground fault identification result.

6. The method for identifying high-resistance grounding faults in power distribution lines according to any one of claims 1-5, characterized in that, Another high-resistance grounding fault identification device is installed between the primary and secondary fusion pole-mounted circuit breaker and the feeder terminal on the other end of the tower of the tested power distribution line. When the grounding fault identification result indicates that the tested power distribution line has a high-resistance grounding fault, the device further includes: Read the absolute arrival time of the first fault traveling wave recorded in the high-resistance grounding fault identification device; Read the absolute arrival time of the second fault traveling wave recorded in the other high-resistance ground fault identification device; According to the line type of the power distribution line under test, a preset line traveling wave propagation velocity table is retrieved, and the corresponding line traveling wave propagation velocity is matched. The target difference is obtained by calculating the difference between the absolute arrival times of the first fault traveling wave and the second fault traveling wave. The target multiplication value is obtained by multiplying the target difference with the traveling wave propagation speed of the line. The target sum is obtained by performing a summation operation using the target multiplier and the preset length of the main trunk of the power distribution line under test. The distance from the fault point to the high-resistance grounding fault identification device is obtained by calculating the ratio between the target sum and the line geometric correction coefficient.

7. A high-resistance grounding fault identification device for power distribution lines, characterized in that, A high-resistance grounding fault identification device is installed between the primary and secondary integrated pole-mounted circuit breaker and the feeder terminal on one end of the power distribution line under test. The high-resistance grounding fault identification device includes: A wideband current transformer is used to collect the real-time line electrical signal of the power distribution line under test. The suspected disturbance detection module is used to determine ground disturbances using the real-time line electrical signal. The traveling wave preprocessing module is used to extract the disturbance traveling wave signal from the real-time line electrical signal and perform preprocessing when the ground disturbance determination result is that there is a suspected ground disturbance, so as to obtain the preprocessed traveling wave signal. The fault identification and judgment module is used to identify ground faults using the preprocessed traveling wave signal to obtain the ground fault identification result of the tested power distribution line.

8. An electronic device, characterized in that, The method includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the high-resistance grounding fault identification method for power distribution lines as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the high-resistance grounding fault identification method for power distribution lines as described in any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, wherein when the program instructions are executed by a computer, the computer performs the high-resistance grounding fault identification method for power distribution lines as described in any one of claims 1-6.

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