A cable fault locating device and method for a cross-bonded system in service

Abstract

The application provides a cable fault positioning device and method in a cross-connection system in operation, which does not need to modify the cross-connection system, and the time difference of the fault breakdown current is captured by the first-end sensor and the last-end sensor to position, solves the problems that the traditional method needs to disassemble the grounding system and depends on the experience of complex waveform identification, and improves the efficiency, accuracy and on-site operation convenience of long-distance cable fault positioning; the cable fault positioning device, the measured fault cable grounding system is in a cross-connection operation state, and comprises an impulse voltage unit, a first-end sampling unit, a last-end sampling unit and a data processing system; the impulse voltage unit generates an impulse voltage for making the cable fault click discharge; the first-end sampling unit filters the high-frequency impulse current generated when the impulse voltage unit discharges, provides a freewheeling channel for the pulse current generated by the cable fault click, collects the pulse current generated by the cable fault click, and records and uploads to the data processing system.

Description

Technical Field

[0001] This invention relates to the field of cable fault location technology, and specifically to a cable fault location device and method for a cross-connected system in operation. Background Technology

[0002] In recent years, with the continuous growth of my country's electricity demand, the ongoing transformation of energy structure, and the rapid development of urbanization, high-voltage and ultra-high-voltage cables have gradually replaced traditional overhead transmission lines and become an important carrier of the power transmission backbone network. The continuous improvement of cable application voltage levels, the continuous increase in application scale, and the continuous growth of single-circuit length have become typical characteristics of the development of the cable industry.

[0003] With the continuous increase in cable loop length, rapid and accurate cable fault location is of great significance for the high-quality operation of cable lines. Currently, the traditional impulse-flash method for cable fault location requires converting the cross-connected cable line system into a straight-through state, and locating the cable fault by the reflection of the fault wave in the line. This makes the fault location of long-distance cable lines complicated, labor-intensive, time-consuming, and requires high-level waveform recognition technology, making it difficult to adapt to the current situation of cable operation and maintenance with the continuous increase in loop length.

[0004] The defects and shortcomings of the existing technology are as follows:

[0005] 1) Existing fault location technology requires converting the cross-connection system of cable lines into a straight-through state, which involves a large workload and seriously affects the efficiency of fault location.

[0006] 2) Existing fault location technology relies on the reflection of the flashover waveform at the fault point in the line for location, which requires the ability to accurately identify the corresponding reflected waveform, and has high technical requirements.

[0007] Given the limitations of the existing technologies, they are no longer adequate for the current state of cable maintenance, which involves increasing loop lengths and increasingly stringent maintenance requirements. To overcome the bottlenecks of traditional methods, there is an urgent need to develop a new fault location technology and device that can achieve rapid and accurate fault location without large-scale modifications to the existing grounding system. Summary of the Invention

[0008] This invention aims to address the technical deficiencies of existing technologies by providing a cable fault location device and method for cross-connected systems in operation. It eliminates the need to modify the cross-connected system and locates faults by capturing the time difference of fault breakdown current through sensors at the beginning and end of the cable. This completely solves the problems of traditional methods that require disassembling the grounding system and relying on experience in identifying complex waveforms, and significantly improves the efficiency, accuracy, and convenience of on-site operation for long-distance cable fault location.

[0009] The present invention provides the following technical solution: On one hand, it discloses a cable fault location device in the operation state of a cross-interconnected system, wherein the grounding system of the faulty cable under test is in the cross-interconnected operation state, including an impulse voltage unit, a first-end sampling unit, an end-end sampling unit, and a data processing system;

[0010] The impulse voltage unit generates an impulse voltage that causes the cable fault point to discharge.

[0011] The first-end sampling unit filters out the high-frequency impulse current generated during the discharge of the impulse voltage unit, provides a follow current channel for the pulse current generated by the cable fault point puncture, collects the pulse current generated by the cable fault point puncture, records the amplitude and corresponding time of the pulse current, and uploads the collected data to the data processing system;

[0012] The end sampling unit provides a follow current channel for the pulse current generated by the cable fault puncture, collects the pulse current generated by the cable fault puncture, records the amplitude and corresponding time of the pulse current, and uploads the collected data to the data processing system;

[0013] The data processing system receives the data collected by the first-end sampling unit and the last-end sampling unit, and calculates the distance to the fault point of the tested faulty cable.

[0014] Furthermore,

[0015] The impulse voltage unit includes a test transformer T1, a rectifier silicon stack VD1, an energy storage capacitor C1, and a discharge ball gap Q1. The primary side of the test transformer T1 is connected to an external power supply, and the high-voltage terminal of the secondary side of the test transformer T1 is connected to the end of the rectifier silicon stack VD1. The first end of the rectifier silicon stack VD1 is connected to the high-voltage terminal of the energy storage capacitor C1 and the first end of the discharge ball gap Q1. The tail end of the discharge ball gap Q1 is connected to the first end sampling unit.

[0016] Furthermore,

[0017] The first-end sampling unit includes a charging resistor R1, a filter capacitor C2, and a sampling module high-frequency current sensor CY1. The tail end of the discharge ball gap Q1 is connected to the first end of the charging resistor R1. The tail end of the charging resistor R1 and the high-voltage terminal of the filter capacitor C2 are connected to the first end of the conductor of the faulty cable under test. The sampling module high-frequency current sensor CY1 is set on the high-voltage output line connected to the high-voltage terminal of the filter capacitor C2 and the first end of the conductor of the faulty cable under test for signal acquisition.

[0018] Furthermore,

[0019] The end sampling unit includes a freewheeling capacitor C3 and a sampling module high-frequency current sensor CY2. The end of the conductor of the faulty cable under test is connected to the high-voltage end of the freewheeling capacitor C3, and the low-voltage end of the freewheeling capacitor C3 is connected to the ground of the cable system. The low-voltage end of the secondary side of the test transformer T1, the low-voltage end of the energy storage capacitor C1, and the low-voltage end of the filter capacitor C2 are connected to the ground of the cable system. The sampling module high-frequency current sensor CY2 is set on the high-voltage connection line connecting the high-voltage end of the freewheeling capacitor C3 and the end of the conductor of the faulty cable under test for signal acquisition.

[0020] Furthermore,

[0021] Adjust the spacing of the discharge ball gap Q1 according to the voltage threshold required for cable fault point breakdown, so as to ensure that the voltage on the energy storage capacitor C1 can discharge the cable fault point after the discharge ball gap Q1 breaks down.

[0022] Furthermore,

[0023] The data processing system is mounted on a host computer, and the system includes:

[0024] The data receiving module is communicatively connected to the first sampling unit and the last sampling unit, and is used to receive the collected data;

[0025] The data analysis processor is electrically connected to the data receiving module, calls the preset fault location algorithm embedded in the host computer, processes the collected data, calculates and outputs the distance to the fault point of the tested fault cable.

[0026] Furthermore,

[0027] The external power supply is either AC 220V or 380V.

[0028] Another aspect of the present invention discloses a method for locating cable faults in a cross-connection system during operation, comprising the following steps:

[0029] Connect the cable fault location device to the conductor of the faulty cable under test, and adjust the discharge ball gap Q1 to the preset discharge distance;

[0030] The external power supply charges the energy storage capacitor C1 through the test transformer T1 and the rectifier silicon stack VD1. When the voltage on the energy storage capacitor C1 reaches the discharge voltage of the discharge ball gap Q1, the discharge ball gap Q1 breaks down. The energy storage capacitor C1 charges the conductor of the faulty cable under test through the first-end sampling unit, generating an impulse voltage wave on the conductor of the faulty cable under test.

[0031] The impulse voltage wave causes the cable fault point to break down, generating a pulse discharge current. The pulse discharge current propagates from the fault point to both ends of the cable and is collected by the high-frequency current sensor CY1 at the beginning and the high-frequency current sensor CY2 at the end. The high-frequency current sensor CY1 and the high-frequency current sensor CY2 record the times t1 and t2 when the pulse current arrives at the two sensors, respectively, and calculate the distance to the fault point of the tested cable based on the collected data.

[0032] Furthermore,

[0033] The distance to the fault point of the tested faulty cable is calculated using the following formula:

[0034] Where L is the distance from the fault point to the beginning, Lm is the total length of the cable, and v is the wave velocity of the cable.

[0035] This invention discloses a cable fault location device for a cross-connection system in operation, which significantly improves fault location efficiency and eliminates the need for cumbersome modifications to the cable cross-connection system. By using high-frequency current sensors at both ends to record pulse time differences for location, it completely avoids the technical difficulties of traditional methods that rely on complex reflected waveform identification, greatly reducing the experience requirements for maintenance personnel. It is especially suitable for long-distance cable lines and is not limited by grounding methods. At the same time, the device has a signal filtering function to ensure the accuracy of the collected data.

[0036] First, it significantly improves fault location efficiency and breaks through the bottleneck of system reconnection. Addressing the issue that "existing technologies require reconnecting cross-connection systems to a straight-through state, resulting in a large workload and long processing time," this device utilizes the collaborative working mode of the first-end sampling unit and the last-end sampling unit, completely eliminating the need for reconnection operations on cross-connection systems. After a cable line fault occurs, maintenance personnel do not need to enter the site to perform complex disassembly and wiring work to change the original grounding method. By directly utilizing the high-frequency current signal generated at the fault point, combined with the installed high-frequency current sensors (CY1, CY2), location work can be carried out. This design compresses the reconnection preparation time, which originally required several hours or even longer, to near zero, greatly simplifying the work process and significantly improving the overall efficiency of fault location for long-distance cable lines.

[0037] Secondly, this method avoids the technical difficulties of relying on complex reflected waveform identification and reduces the experience requirements for maintenance personnel. Addressing the issue that "traditional impulse-flash methods require accurate identification of reflected waveforms, demanding high levels of technical expertise," this device introduces a time-difference-based positioning principle. The impulse voltage unit is only used to trigger discharge, while the core positioning data comes from the arrival times (t1 and t2) of the pulse current recorded by the first and last sampling units. The data processing system can determine the fault location through simple mathematical calculations. This method no longer relies on technicians identifying weak secondary and tertiary reflected waves from complex waveforms, transforming subjective experience-based judgment into objective time measurement. This not only reduces the technical requirements for maintenance personnel but also fundamentally reduces positioning errors caused by waveform misinterpretation, making the positioning results more intuitive and reliable.

[0038] Finally, the system is adapted to long-distance and complex grounding systems, optimizes signal acquisition, and ensures data accuracy;

[0039] Addressing the issue that "existing technologies are ill-suited to the ongoing maintenance of high-voltage cables with ever-increasing loop lengths," this device fully considers the unique cross-interconnection grounding characteristics of long-distance and high-voltage cables. The end sampling unit not only undertakes the data acquisition task but is also specially designed to form a follow current channel for high-frequency currents, ensuring that weak high-frequency pulse currents can effectively propagate to the end of the line and be reliably captured during long-distance transmission. At the same time, since it does not require changes to the topology of the grounding system, this device is perfectly adaptable to various complex cable sheath grounding methods, and has extremely high engineering application value for ultra-high voltage, long-length, and multi-segment cross-interconnected cable lines.

[0040] To address the issue of "signal mixing and significant interference during impact testing using traditional methods": the front-end sampling unit incorporates a signal filtering function, which effectively filters out high-frequency impact interference generated by the impact voltage unit during operation (i.e., the "reflected signal in the line" mixed signal mentioned in the background technology). This allows the front-end sensor to accurately capture the pure pulse current truly generated by the fault point breakdown, avoiding false triggering or data contamination caused by the equipment's own discharge, ensuring the authenticity and accuracy of the time markers (t1 and t2) used for positioning calculation, thereby further improving the positioning accuracy. Attached Figure Description

[0041] Figure 1 This is an overall structural diagram of the present invention;

[0042] Figure 2 A cable simulation system with cross-connection was built for the laboratory;

[0043] Figure 3 Location map of traditional devices in a cross-connected state;

[0044] Figure 4Location map of traditional devices in a cross-connected system converted to a straight-through state;

[0045] Figure 5 The data and positioning results obtained by this invention;

[0046] Figure 6 The positioning results are for locations where R1 and C2 are not connected.

[0047] Figure 7 The location result is for R1 alone;

[0048] Figure 8 The positioning result is shown after connecting the charging resistor R1 and the filter capacitor C2.

[0049] Figure 9 The high-frequency current measured by CY2 is when no freewheeling capacitor is connected at the end.

[0050] Figure 10 The high-frequency current measured by CY2 is the terminal freewheeling capacitor.

[0051] Figure 11 This is a picture of the performance verification test site;

[0052] Figure 12 This is a performance verification test graph. Detailed Implementation

[0053] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0054] like Figures 1-12 As shown, it illustrates a specific embodiment of the present invention:

[0055] like Figures 1-12 As shown, one aspect of the present invention discloses Embodiment 1:

[0056] A cable fault location device for a cross-interconnected system in operation, wherein the grounding system of the faulty cable under test is in cross-interconnected operation, includes an impulse voltage unit, a first-end sampling unit, an end-end sampling unit, and a data processing system, wherein the conductor of the faulty cable under test is connected to the cross-interconnected system in operation;

[0057] An impulse voltage unit generates an impulse voltage waveform that causes a cable fault point to discharge. The impulse voltage unit includes a test transformer T1, a rectifier silicon stack VD1, an energy storage capacitor C1, and a discharge ball gap Q1. The primary side of the test transformer T1 is connected to an external power supply, and the high-voltage terminal of the secondary side of the test transformer T1 is connected to the end of the rectifier silicon stack VD1. The beginning of the rectifier silicon stack VD1 is connected to the high-voltage terminal of the energy storage capacitor C1 and the beginning of the discharge ball gap Q1. The end of the discharge ball gap Q1 is connected to the beginning sampling unit.

[0058] The first-end sampling unit filters out the high-frequency impulse current generated during the discharge of the impulse voltage unit, forms a freewheeling channel for the high-frequency current generated by the cable fault puncture, collects the pulse current generated by the cable fault puncture, records the amplitude and corresponding time of the pulse current, and uploads the collected data to the data processing system. The first-end sampling unit includes a charging resistor R1, a filter capacitor C2, and a sampling module high-frequency current sensor CY1. The tail end of the discharge ball gap Q1 is connected to the head end of the charging resistor R1. The tail end of the charging resistor R1 and the high-voltage end of the filter capacitor C2 are connected to the head end of the conductor of the faulty cable under test. The sampling module high-frequency current sensor CY1 is set on the high-voltage output line connected to the high-voltage end of the filter capacitor C2 and the head end of the conductor of the faulty cable under test for signal acquisition.

[0059] The end sampling unit forms a freewheeling channel for the high-frequency current generated by the cable fault puncture, collects the pulse current generated by the cable fault puncture, records the amplitude and corresponding time of the pulse current, and uploads the collected data to the data processing system. The end sampling unit includes a freewheeling capacitor C3 and a sampling module high-frequency current sensor CY2. The end of the conductor of the faulty cable under test is connected to the high-voltage end of the freewheeling capacitor C3, and the low-voltage end of the freewheeling capacitor C3 is connected to the ground of the cable system. The low-voltage end of the secondary side of the test transformer T1, the low-voltage end of the energy storage capacitor C1, and the low-voltage end of the filter capacitor C2 are connected to the ground of the cable system. The sampling module high-frequency current sensor CY2 is set on the high-voltage connection line connecting the high-voltage end of the freewheeling capacitor C3 and the end of the conductor of the faulty cable under test to collect signals.

[0060] A data processing system receives data collected by the first-end sampling unit and the last-end sampling unit, and calculates the distance to the fault point of the tested faulty cable. The data processing system is integrated into a host computer, and the system includes:

[0061] The data receiving module is communicatively connected to the first sampling unit and the last sampling unit, and is used to receive the collected data;

[0062] The data analysis processor is electrically connected to the data receiving module, calls the preset fault location algorithm embedded in the host computer, processes the collected data, calculates and outputs the distance to the fault point of the tested fault cable.

[0063] The impulse voltage unit in this invention has the following main function: to generate an impulse voltage waveform that causes the cable fault point to discharge. It mainly includes a test transformer T1, a rectifier silicon stack VD1, an energy storage capacitor C1, and a discharge ball gap Q1.

[0064] The primary functions of the sampling unit are: 1) to filter out the high-frequency impulse current generated during the discharge of the discharge ball gap Q1 in the impulse voltage unit, preventing this high-frequency current from being collected by the high-frequency current sensor CY1 in the sampling module and superimposed with the high-frequency current generated by the cable fault puncture, thus failing to accurately capture the time t1 at which the high-frequency current of the fault puncture is transmitted to the high-frequency current sensor CY1 in the sampling module. 2) The high-frequency current sensor CY1 in the sampling module is located on the high-voltage output line connected to the cable conductor at the high-voltage end of the filter capacitor. This sensor is used to collect the pulse current generated by the cable fault puncture, record the amplitude and corresponding time of the pulse current, and upload the collected data to the data processing system. It mainly includes a charging resistor R1, a filter capacitor C2, and the high-frequency current sensor CY1 in the sampling module.

[0065] The main functions of the end-sampling unit are: first, the freewheeling capacitor C3 forms a freewheeling channel for the high-frequency current generated by the cable fault puncture, facilitating its measurement by the high-frequency current sensor CY2 of the sampling module located at the cable end; second, the high-frequency current sensor CY2 of the sampling module, located on the high-voltage connection line connecting the high-voltage end of the freewheeling capacitor to the cable conductor, is used to collect the pulse current generated by the cable fault puncture, record the amplitude and corresponding time of the pulse current, and upload the collected data to the data processing system.

[0066] The main functions of the data processing system are: to receive the data collected by the first-end sampling unit and the last-end sampling unit, and to calculate the distance to the fault point of the tested faulty cable.

[0067] Figure 2 The cable simulation system with cross-connection system was built in the laboratory. The cable was 150m long and a cross-connection box was set up every 50m. The left side was the starting end and the simulated fault point was 100m away from the starting end.

[0068] The differences between this embodiment and traditional cable fault location devices in specific experiments are as follows:

[0069] (1) Different sampling locations for high-frequency current sensors. Traditional cable fault location devices sample signals from the ground wire connected to the cable grounding system. In this scheme, the high-frequency current sensor of the cable fault location device samples signals from the high-voltage connection line between the device and the cable head conductor, the cable end conductor and the freewheeling capacitor. Because traditional fault location devices collect signals from the ground wire, when the cable cross-interconnected grounding system is in operation, the high-frequency current generated by the fault point breakdown will produce a complex reflection process in the cross-interconnected grounding system, making it difficult to calculate the distance to the fault point from the measured fault current waveform through the reflection law. In this scheme, the cable fault location device collects signals from the connection line between the device and the cable conductor. At the same time, by combining the time when the high-frequency current generated by the fault point breakdown propagates to the two sensors with the relative position of the two sensors, the distance to the cable fault point is calculated, avoiding the influence of the cross-interconnected system on fault location. Therefore, fault location can be achieved when the cross-interconnected system is in operation.

[0070] (2) Compared with traditional fault location devices, the key to accurate positioning of the cable fault location device in this scheme lies in accurately obtaining the times t1 and t2 when the high-frequency current generated by the fault puncture is transmitted to the two sensors. As can be seen from the structural diagrams of the traditional fault location device and the cable fault location device in this scheme, before the energy storage capacitor discharges to the faulty cable under test, the discharge ball gap Q1 will break down first. When the ball gap Q1 breaks down, it will also generate a high-frequency pulse current. If no processing is done, this high-frequency pulse current will be collected by CY1 and CY2 and superimposed with the high-frequency pulse current generated by the fault puncture of the cable under test, resulting in the inability to accurately capture the times t1 and t2 when the high-frequency current generated by the fault puncture is transmitted to the two sensors, ultimately leading to positioning failure. Therefore, compared with the traditional cable fault location device, this device adds a charging resistor R1 and a filter capacitor C2 after the discharge ball gap. R1 and C2 filter out the high-frequency current generated by the breakdown of the discharge ball gap, preventing it from being collected by CY1 and CY2 and ultimately affecting the positioning result.

[0071] like Figures 3-5 The accuracy of the positioning in this solution can be seen. Figure 3 The positioning map of the traditional device in the cross-interconnected state (positioning at 126 meters, with a huge deviation). Figure 4 The location map of the traditional device in the cross-interconnection system is changed to a straight-through state (location 103 meters, can be located). Figure 5 The data and positioning results obtained by this device (positioning at 101 meters);

[0072] like Figures 6-8 The waveforms of CY1 and CY2 before and after adding R1 and C2 are shown respectively. Figure 6 R1 and C2 are not connected (the positioning position is 4m, which is the location of the discharge ball gap). Figure 7Connect R1 (3000Ω) separately (located at 3m, i.e., the location of the discharge ball gap). Figure 8 The positioning result after connecting the charging resistor R1 and the filter capacitor C2 (the positioning position is 101m, which is the location of the discharge ball gap).

[0073] (3) Compared with traditional positioning devices, this device introduces a freewheeling capacitor at the end of the faulty cable under test, providing a propagation path for the high-frequency pulse current generated by the fault breakdown, and ensuring that the high-frequency current sensor CY2 in the end sampling module can collect the high-frequency pulse current generated by the fault breakdown. Figures 9-10 The high-frequency current waveforms measured by CY2 were tested under two conditions: with and without a freewheeling capacitor C3 connected at the end.

[0074] In addition to the 150-meter simulated circuit built in the laboratory, this embodiment also conducted tests on an 800-meter-long cable in the laboratory (simulating a fault at 300 meters). Figures 11-12 A set of sensors was deployed at 0m, 600m, 700m, and 800m respectively. The test results are shown in the figure. As can be seen from the figure, the arrival times of the pulse current collected by the sensors at 0m (the beginning of the figure) and 600m are consistent, indicating that the fault point is located in the middle of the two points, which is consistent with the set location. The arrival times of the pulse current collected by the sensors at 600m, 700m, and 800m are the same, which is consistent with the relative position of the sensor deployment. This verifies that this scheme can accurately capture the time and waveform of the pulse current generated by the fault point to be transmitted to the sensors at each point, thereby achieving accurate location of the cable fault point.

[0075] Specifically, the spacing of the discharge ball gap Q1 is adjusted according to the voltage threshold required for the cable fault to break down, so as to ensure that the voltage on the energy storage capacitor C1 can discharge the cable fault point after the discharge ball gap Q1 breaks down.

[0076] Before fault location, the voltage threshold required for fault breakdown is first estimated based on the type, length, and insulation condition of the cable under test. The breakdown voltage is then set by adjusting the spacing of the discharge gaps Q1. Specifically, increasing the gap spacing increases the breakdown voltage, while decreasing it decreases it. After adjustment, the energy storage capacitor C1 is charged. When the capacitor voltage reaches the set breakdown value of the discharge gap Q1, the gap breaks down instantaneously, generating a high-voltage shock wave applied to the faulty phase of the cable. This shock wave propagates along the cable to the fault point, forcing the insulation at the fault point to break down and discharge, thereby generating a high-frequency pulse current for fault location. By precisely adjusting the gap spacing, it is ensured that the voltage on the energy storage capacitor C1 still has sufficient energy to reliably discharge the fault point after the gap breaks down, while avoiding unnecessary impact damage to the intact parts of the cable due to excessive voltage.

[0077] Specifically, the external power supply is an AC 220V or 380V power supply. This external power supply, an AC 220V or 380V power supply, is used to boost and rectify the industrial frequency AC power to charge the energy storage capacitor C1.

[0078] Another aspect of the present invention discloses Embodiment 2:

[0079] A method for locating cable faults in a cross-connection system during operation comprises the following steps:

[0080] Connect the cable fault location device to the conductor of the faulty cable under test, and adjust the discharge ball gap Q1 to the preset discharge distance;

[0081] The external power supply charges the energy storage capacitor C1 through the test transformer T1 and the rectifier silicon stack VD1. When the voltage on the energy storage capacitor C1 reaches the discharge voltage of the discharge ball gap Q1, the discharge ball gap Q1 breaks down. The energy storage capacitor C1 charges the conductor of the faulty cable under test through the first-end sampling unit, generating an impulse voltage wave on the conductor of the faulty cable under test.

[0082] The impulse voltage wave causes the cable fault point to break down, generating a pulsed discharge current. This pulsed discharge current propagates from the fault point to both ends of the cable and is collected by high-frequency current sensor CY1 at the beginning and high-frequency current sensor CY2 at the end. High-frequency current sensors CY1 and CY2 record the times t1 and t2 when the pulse current arrives at the two sensors, respectively. The distance to the fault point of the tested cable is calculated based on the collected data using the following formula:

[0083] Where L is the distance from the fault point to the beginning, Lm is the total length of the cable, and v is the wave velocity of the cable.

[0084] This positioning method has the following beneficial effects:

[0085] Simple to operate and highly controllable: By presetting the spacing of the discharge spheres Q1, the breakdown voltage threshold can be flexibly set according to the cable type and fault condition, ensuring that the voltage on the energy storage capacitor C1 can reliably break down the fault point while avoiding unnecessary impact damage to the intact parts of the cable. Meanwhile, it uses conventional AC 220V or 380V power supplies, adapting to various on-site power conditions, eliminating the need for a dedicated high-voltage power supply, thus improving the device's versatility and convenience.

[0086] Significantly improved positioning efficiency: This method completely eliminates the cumbersome operation of converting the cable cross-connection system to a straight-through state, a traditional technique. While the cross-connection system remains in its original operational state, voltage is directly applied through the impulse voltage unit to cause the fault to break down. Signals are collected by sensors at both ends, reducing the preparation time for reconnection from several hours to minutes, greatly shortening unplanned downtime for cable lines.

[0087] Avoiding the waveform recognition challenge: The dual-end traveling wave method is adopted, based on the absolute time difference between the arrival of the pulse current generated by the fault puncture at the first sensor CY1 and the last sensor CY2. This method does not rely on the complex reflected waveform recognition of traditional impulse-flash methods, and does not require technicians to have extensive waveform analysis experience. It fundamentally avoids positioning errors caused by waveform misjudgment, making the positioning results more intuitive and accurate.

[0088] Adaptable to long-distance and complex grounding systems: By installing a sampling module (high-frequency current sensor CY2) at the cable end, a complete freewheeling path for high-frequency current is provided, ensuring that pulse current can effectively propagate to the end of the line and be reliably captured. Combined with calculation formulas... This method is applicable to cable lines of various lengths and is not limited by the cross-interconnection grounding method of high-voltage cables, thus having wide engineering applicability.

[0089] In summary, this method enables rapid and accurate fault location of cables without altering the cross-connection system, utilizing the time difference principle at both ends. This significantly improves the efficiency and accuracy of fault location in long-distance cable lines, and reduces the technical threshold and workload of maintenance work.

[0090] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. These changes involve related technologies well known to those skilled in the art, and all of them fall within the protection scope of the present invention.

[0091] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A cable fault location device for a cross-connected system in operation, wherein the grounding system of the faulty cable under test is in a cross-connected operating state, characterized in that, It includes an impulse voltage unit, a first-end sampling unit, an end-end sampling unit, and a data processing system; The impulse voltage unit generates an impulse voltage that causes the cable fault point to discharge. The first-end sampling unit filters out the high-frequency impulse current generated during the discharge of the impulse voltage unit, provides a follow current channel for the pulse current generated by the cable fault point puncture, collects the pulse current generated by the cable fault point puncture, records the amplitude and corresponding time of the pulse current, and uploads the collected data to the data processing system; The end sampling unit provides a follow current channel for the pulse current generated by the cable fault puncture, collects the pulse current generated by the cable fault puncture, records the amplitude and corresponding time of the pulse current, and uploads the collected data to the data processing system; The data processing system receives the collected data from the first-end sampling unit and the last-end sampling unit, and calculates the distance to the fault point of the tested faulty cable. The impulse voltage unit includes a test transformer T1, a rectifier silicon stack VD1, an energy storage capacitor C1, and a discharge ball gap Q1. The primary side of the test transformer T1 is connected to an external power supply, the high-voltage terminal of the secondary side of the test transformer T1 is connected to the end of the rectifier silicon stack VD1, the first end of the rectifier silicon stack VD1 is connected to the high-voltage terminal of the energy storage capacitor C1 and the first end of the discharge ball gap Q1, and the tail end of the discharge ball gap Q1 is connected to the first end sampling unit. The first-end sampling unit includes a charging resistor R1, a filter capacitor C2, and a sampling module high-frequency current sensor CY1. The tail end of the discharge ball gap Q1 is connected to the first end of the charging resistor R1. The tail end of the charging resistor R1 and the high-voltage end of the filter capacitor C2 are connected to the first end of the conductor of the faulty cable under test. The sampling module high-frequency current sensor CY1 is set on the high-voltage output line connected to the high-voltage end of the filter capacitor C2 and the first end of the conductor of the faulty cable under test for signal acquisition. The end sampling unit includes a freewheeling capacitor C3 and a sampling module high-frequency current sensor CY2. The end of the conductor of the faulty cable under test is connected to the high-voltage terminal of the freewheeling capacitor C3. The sampling module high-frequency current sensor CY2 is set on the high-voltage connection line connected to the high-voltage terminal of the freewheeling capacitor C3 and the end of the conductor of the faulty cable under test for signal acquisition. Furthermore, the low-voltage terminals of the freewheeling capacitor C3, the secondary side of the test transformer T1, the energy storage capacitor C1, and the filter capacitor C2 are all connected to the grounding of the cable system.

2. The cable fault location device for a cross-connection system under operating conditions according to claim 1, characterized in that, Adjust the spacing of the discharge ball gap Q1 according to the voltage threshold required for cable fault point breakdown, so as to ensure that the voltage on the energy storage capacitor C1 can discharge the cable fault point after the discharge ball gap Q1 breaks down.

3. The cable fault location device for a cross-connection system under operating conditions according to claim 1, characterized in that, The data processing system is mounted on a host computer, and the system includes: The data receiving module is communicatively connected to the first sampling unit and the last sampling unit, and is used to receive the collected data; The data analysis processor is electrically connected to the data receiving module, calls the preset fault location algorithm embedded in the host computer, processes the collected data, calculates and outputs the distance to the fault point of the tested fault cable.

4. The cable fault location device for a cross-connection system under operating conditions according to claim 1, characterized in that, The external power supply is either AC 220V or 380V.

5. A method for locating cable faults in a cross-connection system during operation, characterized in that, Using the cable fault location device for a cross-connection system in operation as described in any one of claims 1-4, the following steps are performed: Connect the cable fault location device to the conductor of the faulty cable under test, and adjust the discharge ball gap Q1 to the preset discharge distance; The external power supply charges the energy storage capacitor C1 through the test transformer T1 and the rectifier silicon stack VD1. When the voltage on the energy storage capacitor C1 reaches the discharge voltage of the discharge ball gap Q1, the discharge ball gap Q1 breaks down. The energy storage capacitor C1 charges the conductor of the faulty cable under test through the first-end sampling unit, generating an impulse voltage wave on the conductor of the faulty cable under test. The impulse voltage wave causes the cable fault point to break down, generating a pulse discharge current. The pulse discharge current propagates from the fault point to both ends of the cable and is collected by the high-frequency current sensor CY1 at the beginning and the high-frequency current sensor CY2 at the end. The high-frequency current sensor CY1 and the high-frequency current sensor CY2 record the times t1 and t2 when the pulse current arrives at the two sensors, respectively, and calculate the distance to the fault point of the tested cable based on the collected data.

6. The cable fault location method for a cross-connection system in operation according to claim 5, characterized in that, The distance to the fault point of the tested faulty cable is calculated using the following formula: Where L is the distance from the fault point to the beginning, Lm is the total length of the cable, and v is the wave velocity of the cable.

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