Overhead line leakage current detection device and detection method thereof

Abstract

The invention discloses an overhead line leakage current detection device and a detection method thereof, and belongs to the technical field of power system overhead line detection. The device comprises a plurality of current acquisition units, a signal transmission unit, an insulation operation unit and a signal processing unit. The current acquisition unit is used for acquiring current signals of each phase and a neutral line of an overhead line, the signal transmission unit transmits the signals, the insulation operation unit realizes safe hanging and evacuation of the acquisition unit, and the signal processing unit measures a current signal vector sum through a built-in current transformer so as to calculate a leakage current value. The method comprises the steps of hanging the acquisition unit, transmitting a signal, calculating leakage current and positioning a fault point. The automatic clamping and evacuating structure reduces the labor intensity, the V-shaped clamping structure ensures accurate butt joint of the magnetic rings, electric leakage faults can be rapidly detected and positioned in a non-power-off state, the power maintenance efficiency and the operation safety are improved, meanwhile, the three-phase unbalance degree and line load monitoring function is achieved, and the application range is wide.

Description

Technical Field

[0001] This invention relates to the field of power system testing technology, specifically to an overhead line leakage current detection device and its detection method. Background Technology

[0002] In power system operation and maintenance, overhead lines, due to their long-term exposure to the outdoor environment, are susceptible to damage from factors such as wind, rain, aging, and external forces, leading to damage to the cable insulation and subsequently causing grounding or phase-to-phase short circuits, resulting in leakage current. Leakage current not only causes a significant increase in line losses and reduces the economic benefits for power grid companies, but it can also trigger leakage protection tripping, user power outage complaints, and even serious safety accidents such as fires and electric shocks. Therefore, leakage current detection of overhead lines is a core daily task for power maintenance personnel.

[0003] Current leakage current detection mainly relies on clamp-on leakage current detectors, which work by simultaneously clamping a three-phase four-wire cable with the jaws and measuring the vector sum of the currents to determine the leakage current. However, the spacing between the A, B, C, and N phases of overhead lines is typically around 1 meter, and the jaw diameter of existing clamp-on detectors cannot accommodate this spacing, making simultaneous clamping difficult. If a separate measuring device is used, it requires multiple disassemblies and reassemblies, which is cumbersome and prone to introducing measurement errors. Furthermore, existing detection devices require operators to hold the instrument and continuously align it with the line, resulting in high labor intensity and high-risk work at heights. Simultaneously, measurement accuracy is greatly affected by the jaw closure degree, and the gap in the magnetic ring connection can easily lead to current induction deviations, failing to meet the requirements for high-precision detection.

[0004] To address the aforementioned issues, there is an urgent need for a leakage current detection device and method that can adapt to the large spacing of overhead lines, is easy to operate, provides accurate measurements, and enables fault location, thereby improving power maintenance efficiency and operational safety. Summary of the Invention

[0005] The purpose of this invention is to provide an overhead line leakage current detection device and its detection method, which solves the problems of existing devices being unable to adapt to large spacing of overhead lines, cumbersome operation, low measurement accuracy, and difficulty in fault location.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, an overhead line leakage current detection device is provided, comprising:

[0008] Multiple current acquisition units are used to acquire the current signals of each phase line and the neutral line in the overhead line respectively. The current acquisition unit has an openable and closable clamping structure to achieve detachable connection with the line.

[0009] The signal transmission unit is connected at one end to each of the current acquisition units and is used to transmit the current signal acquired by the current acquisition unit.

[0010] An insulated operating unit is detachably connected to each of the current acquisition units and is used by operators to perform overhead line installation and removal operations on the current acquisition units on the ground or in a safe area.

[0011] A signal processing unit is connected to the other end of the signal transmission unit. The signal processing unit has a built-in high-precision current transformer. The high-precision current transformer is used to simultaneously acquire each of the current signals and measure their vector sum. The signal processing unit is also used to calculate the leakage current value of the overhead line based on the vector sum.

[0012] As a further improvement to the technical solution of the present invention, the current acquisition unit includes a housing, two rotatable clamps, two rotating shafts, and two compression springs; the housing is provided with a U-shaped mounting area, a signal interface, and a connection interface, the signal interface being connected to the signal transmission unit, and the connection interface being detachably connected to the insulation operation unit; the U-shaped mounting area is used to pre-mount the current acquisition unit onto an overhead line; the two clamps are symmetrically mounted on both sides of the U-shaped mounting area of ​​the housing via the rotating shafts, and the compression springs are sleeved on the rotating shafts, with their ends respectively abutting against the housing and the clamps, for driving the two clamps to automatically close to clamp the line.

[0013] As a further improvement to the technical solution of the present invention, an arc-shaped guide area is provided at the end of the clamp away from the rotating shaft. The arc-shaped guide area is used to make the two clamps open outward against the elastic force of the compression spring when the insulation operation unit applies external force, so as to realize the automatic clamping and automatic withdrawal of the current acquisition unit from the overhead line.

[0014] As a further improvement to the technical solution of the present invention, each of the two clamps is provided with a semi-circular magnetic ring on its inner side. When the two semi-circular magnetic rings are closed, they form a complete current sensing magnetic ring for collecting line current signals. One of the clamps is provided with at least two V-shaped blocks on its inner side, and the other clamp is provided with V-shaped grooves corresponding to the V-shaped blocks. When the two clamps are closed, the V-shaped blocks are inserted into the V-shaped grooves to achieve precise docking of the two semi-circular magnetic rings.

[0015] As a further improvement to the technical solution of the present invention, the signal processing unit further includes a display module, a storage module, and a communication module; the display module is used to display the leakage current value, the current value of each phase, the three-phase imbalance, and the line load parameters in real time; the storage module is used to store at least 1000 sets of detection data; the communication module includes a Bluetooth unit and a USB interface unit, used to transmit the detection data to a mobile terminal or computer device.

[0016] A second aspect of the present invention provides a method for detecting leakage current in overhead lines, comprising the following steps:

[0017] S1: The operator uses the insulation operation unit to hang multiple current acquisition units on each phase line and neutral line of the overhead line, so that the clamping structure of each current acquisition unit clamps the corresponding line and acquires the current signal.

[0018] S2: Each of the current acquisition units transmits the acquired current signal to the signal processing unit through the signal transmission unit;

[0019] S3: The signal processing unit acquires all the current signals through the built-in high-precision current transformer, calculates the vector sum of each current signal, and obtains the leakage current value of the overhead line based on the vector sum. The calculation formula for the leakage current value is: I0 = |I_A + I_B + I_C + I_N|, where I0 is the leakage current value, I_A, I_B, and I_C are the current signals of the three-phase lines A, B, and C, respectively, and I_N is the current signal of the neutral line.

[0020] S4: The signal processing unit determines whether there is a leakage fault in the overhead line based on the leakage current value and the preset natural leakage current threshold range. If there is a leakage fault, the leakage fault point is located.

[0021] As a further improvement to the technical solution of the present invention, in step S1, the step of mounting the plurality of current acquisition units on each phase line and the neutral line of the overhead line specifically includes:

[0022] S11: The connection interface between the insulation operation unit and the current acquisition unit is detachably connected, and the signal transmission unit is connected to the signal interface of the current acquisition unit;

[0023] S12: The operator holds the insulating operating unit and brings the arc-shaped guide area of ​​the current acquisition unit close to the target line;

[0024] S13: Pull the insulation operation unit away from the line, so that the two clamps open outward against the spring force of the compression spring until the line enters the U-shaped mounting area; S14: Release the insulation operation unit, the compression spring resets and drives the two clamps to close, the V-block is inserted into the V-groove, and the semi-circular magnetic ring is precisely aligned to complete the mounting.

[0025] As a further improvement to the technical solution of the present invention, step S4, namely locating the leakage fault point, specifically includes:

[0026] S41: Select two measurement points on the leakage current branch line, and mark them as measurement point 1 and measurement point 2 respectively. Measurement point 1 is close to the transformer output terminal, and measurement point 2 is far away from the transformer output terminal.

[0027] S42: At measurement point 1 and measurement point 2, the current signals of each phase and the neutral line are collected by the current acquisition unit, and the leakage current vector sum of the two measurement points is calculated and denoted as I_i1 and I_i2 respectively;

[0028] S43: Compare the magnitudes of I_i1 and I_i2: If I_i1≈I_i2, it is determined that there is no leakage fault between the two measurement points, and new measurement points are selected in the direction away from the transformer, repeating steps S42-S43; if I_i1>I_i2, it is determined that there is a leakage fault between the two measurement points, and new measurement points are selected between the two measurement points using the binary search method, repeating steps S42-S43 until the specific fault point is located.

[0029] As a further improvement to the technical solution of the present invention, in step S4, the preset natural leakage current threshold range is 10mA to 100mA; when the leakage current value of the overhead line exceeds 1.5 to 2 times the natural leakage current threshold range, or is continuously higher than 300mA and there is no clear equipment interference cause, it is determined that there is a leakage fault in the overhead line.

[0030] As a further improvement to the technical solution of the present invention, step S5 is also included: the detected leakage current value, phase current value, fault location information and detection time are uploaded to a mobile terminal or computer device through the communication module of the signal processing unit to generate a leakage current detection report. The detection report includes the fault line number, fault point distance, leakage current peak value and suggested maintenance plan.

[0031] A third aspect of the present invention provides a computer device including a memory and a processor, the memory storing a computer program and the processor being configured to execute the computer program to implement the overhead line leakage current detection method as described above.

[0032] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the overhead line leakage current detection method as described above.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The overhead line leakage current detection device and its detection method of the present invention firstly effectively solve the technical pain point of existing clamp-on leakage current detectors being unable to adapt to the large spacing of about 1 meter between the A, B, C, and N phases of overhead lines due to the limitation of the aperture. Multiple independent hook-type current acquisition units are respectively mounted on each line, achieving current signal acquisition without simultaneous clamping. The arc-shaped guide area of ​​the acquisition unit, in conjunction with the compression spring, forms an automatic clamping and retraction structure. Operators can complete the installation and retraction operations on the ground using a telescopic insulating rod, eliminating the need for continuous hand-held alignment or high-altitude work, greatly reducing labor intensity and avoiding the risk of electric shock. Simultaneously, the U-shaped hanging area and V-shaped block-V-groove clamping structure ensure precise alignment of the semi-circular magnetic rings when the clamps are closed. The precise alignment of the two semi-circular magnetic rings and the double-layer shielded signal line significantly improve the current acquisition accuracy, enabling accurate detection of the current in the transmission line. The signal processing unit incorporates a high-precision current transformer, using I0 = |I_A + I_B + I_C +I_N|. The formula calculates leakage current values ​​and supports monitoring of three-phase imbalance, line load, and harmonic parameters. Combined with preset natural leakage current threshold ranges (1mA~10mA for dry, well-insulated lines, 50mA~300mA for damp, old lines), it effectively avoids misjudgments or missed faults. The detection method uses a binary search to compare the vector sum of leakage currents at different measurement points, enabling rapid fault location (accuracy ≤5 meters), solving the problem of blind inspections in traditional methods. It also supports uploading detection data to mobile terminals or computers via Bluetooth or USB interface, and, in conjunction with the accompanying APP, generates a detection report including the fault line number, fault distance, peak leakage current, and repair plan, achieving data traceability and digital operation and maintenance. The overall solution supports uninterrupted power supply detection, avoiding user complaints due to power outages, reducing line losses and power grid company revenue loss. It is also adaptable to various scenarios such as overhead lines in low-voltage distribution areas, branch lines, T-connected lines, and repeated neutral grounding, balancing ease of operation, measurement accuracy, and comprehensive functionality, significantly improving power maintenance efficiency and operational safety. Attached Figure Description

[0035] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0036] Figure 1 This is a three-dimensional structural diagram of the current acquisition unit according to an embodiment of the present invention;

[0037] Figure 2 This is a front view of the current acquisition unit according to an embodiment of the present invention.

[0038] Figure 3 for Figure 2 AA section view;

[0039] Figure 4This is a partial internal schematic diagram of the current acquisition unit according to an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of the composition of a computing device according to an embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram illustrating the measurement of total leakage current and branch line leakage current in a transformer substation according to an embodiment of the present invention.

[0042] Figure 7 This is a schematic diagram illustrating the leakage vector and measurement principle of overhead lines according to an embodiment of the present invention;

[0043] Figure 8 This is a schematic diagram of the structure of an overhead line leakage current detection device according to an embodiment of the present invention;

[0044] Figure 9 This is a schematic diagram of the automatic clamping and retraction of the hook-type current clamp according to an embodiment of the present invention;

[0045] Figure 10 This is a schematic diagram illustrating the location of a branch line leakage fault point according to an embodiment of the present invention;

[0046] Figure 11 This is a schematic diagram illustrating the location of the leakage fault point on the T-connection branch line according to an embodiment of the present invention;

[0047] Figure 12 This is a schematic diagram illustrating the location of a leakage fault point on a repeatedly grounded branch line according to an embodiment of the present invention.

[0048] Figure 13 This is a schematic diagram illustrating the measurement of load current, leakage current, and ground current in an embodiment of the present invention.

[0049] Figure 14 This is a schematic diagram of the framework of an overhead line leakage current detection method according to an embodiment of the present invention.

[0050] In the attached diagram: 1-Current acquisition unit; 2-Signal transmission unit; 3-Insulation operation unit; 4-Signal processing unit; 5-Overhead line cable; 11-Housing; 12-Clamp; 13-Spindle; 14-Compression spring; 115-Spring arm; 111-U-shaped hanging area; 112-Signal interface; 113-Connection interface; 121-Arc-shaped guide area; 122-Semi-circular magnetic ring; 123-V-block; 124-V-groove; 125-Clamping area. Detailed Implementation

[0051] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0052] The present invention will be further described in detail below with reference to the accompanying drawings.

[0053] Reference Figures 1 to 4 ,as well as Figure 8 and Figure 9 In a first aspect, the present invention provides an overhead line leakage current detection device, comprising:

[0054] Multiple current acquisition units 1 (hook-type current clamps) are used to acquire the current signals of each phase line and the neutral line in the overhead line respectively. The current acquisition unit 1 has an openable and closable clamping structure to achieve detachable connection with the line.

[0055] The signal transmission unit 2 is connected at one end to each of the current acquisition units 1, and is used to transmit the current signal acquired by the current acquisition unit 1.

[0056] The insulation operation unit 3 is detachably connected to each of the current acquisition units 1, and is used by operators to perform overhead line installation and removal operations on the current acquisition units 1 on the ground or in a safe area.

[0057] The signal processing unit 4 is connected to the other end of the signal transmission unit 2. The signal processing unit 4 has a built-in high-precision current transformer. The high-precision current transformer is used to simultaneously acquire each of the current signals and measure their vector sum. The signal processing unit 4 is also used to calculate the leakage current value of the overhead line based on the vector sum.

[0058] It should be noted that the overhead line leakage current detection device is composed of multiple current acquisition units 1, signal transmission units 2, insulation operation units 3, and signal processing units 4 working together. Multiple current acquisition units 1 are detachably connected to each phase and neutral line of the overhead line, enabling independent acquisition of current signals for each line and meeting the adaptation requirements of large spacing between phases and neutral lines in the overhead line. One end of the signal transmission unit 2 is connected to each current acquisition unit 1 to stably transmit the acquired current signals and avoid external interference during transmission. The insulated operation unit 3 is detachably connected to each current acquisition unit 1, allowing operators to install and remove the current acquisition units 1 on the overhead line from the ground or a safe area without close contact with the overhead line. The signal processing unit 4 is connected to the other end of the signal transmission unit 2. Its built-in high-precision current transformer can simultaneously acquire the current signals transmitted by all current acquisition units 1 and measure the vector sum of these current signals. The signal processing unit 4 then calculates the leakage current value of the overhead line based on the measured vector sum, ultimately achieving accurate detection of leakage current in the overhead line. This device effectively solves the problem that existing clamp-on leakage current detectors cannot adapt to the large spacing between phases and neutral lines of overhead lines due to the limited clamping jaw diameter. It achieves separate acquisition of current for each line through multiple independent current acquisition units 1, eliminating the need to clamp all lines simultaneously. The setting of the insulation operation unit 3 completely avoids the risk of high-altitude operation for operators and greatly reduces labor intensity. The signal processing unit 4 measures the current vector sum through a high-precision current transformer, ensuring the accuracy of leakage current calculation. At the same time, it supports the detection of overhead lines under uninterrupted power conditions, avoiding power outages for users due to power outages. It significantly improves the efficiency and safety of power maintenance and is suitable for leakage current detection scenarios of overhead lines in various low-voltage distribution areas.

[0059] In some embodiments, the current acquisition unit 1 includes a housing 11, two rotatable clamps 12, two rotating shafts 13, and two compression springs 14. The housing 11 has a U-shaped mounting area 111, a signal interface 112, and a connection interface 113. The signal interface 112 is connected to the signal transmission unit 2, and the connection interface 113 is detachably connected to the insulation operation unit 3. The U-shaped mounting area 111 is used to pre-mount the current acquisition unit 1 onto an overhead line. The two clamps 12 are symmetrically mounted on both sides of the U-shaped mounting area 111 of the housing 11 via the rotating shafts 13. The compression springs 14 are sleeved on the rotating shafts 13, and their two ends abut against the housing 11 and the clamps 12, respectively, to drive the two clamps 12 to automatically close and clamp the line. One end of the compression spring 14 abuts against the clamp 12 to form a spring arm 115.

[0060] It should be noted that the housing 11 is made of high-strength insulating material, and the U-shaped mounting area 111 on it can be adapted to the outer diameter of the overhead line cable 5 to achieve pre-fixation of the current acquisition unit 1 on the overhead line. The signal interface 112 on the housing 11 is connected to the signal transmission unit 2 for exporting the acquired current signal. The connection interface 113 on the housing 11 is detachably connected to the insulating operation unit 3 to provide operating support for the operator. Two clamps 12 are symmetrically installed on both sides of the U-shaped mounting area 111 of the housing 11 via a rotating shaft 13 and can rotate freely around the rotating shaft 13. A compression spring 14 is sleeved on the rotating shaft 13, with its two ends abutting against the housing 11 and the clamps 12 respectively. When no external force is applied, the elastic force of the compression spring 14 can drive the two clamps 12 to close automatically, so that the clamps 12 are in close contact with the overhead line, ensuring the stability of the current signal acquisition. When disassembly is required, external force can be applied through the insulating operation unit 3 to make the clamps 12 open against the spring force. The current acquisition unit 1 features a compact and stable structure. The insulating material of the housing 11, combined with the U-shaped mounting area 111, ensures operational safety and reliably pre-fixes the acquisition unit to the line. The rotatable clamp 12, in conjunction with the compression spring 14, enables automatic closing of the clamp 12, eliminating the need for manual adjustment and simplifying the operation. The detachable connection design of each component facilitates future maintenance and replacement of the acquisition unit, reducing equipment maintenance costs. Furthermore, the automatically closing clamp 12 ensures tight contact with the line, reducing measurement errors caused by poor contact and further improving the accuracy of current signal acquisition.

[0061] In some embodiments, the clamp 12 is provided with an arc-shaped guide area 121 at one end away from the rotating shaft 13. The arc-shaped guide area 121 is used to make the two clamps 12 open outward against the elastic force of the compression spring 14 when the insulation operation unit 3 applies external force, so as to realize the automatic clamping and automatic withdrawal of the current acquisition unit 1 from the overhead line.

[0062] It should be noted that an arc-shaped guide area 121 is provided at the end of the clamp 12 away from the rotating shaft 13. The curvature of the arc-shaped guide area 121 is adapted to the outer diameter of the overhead line cable 5. When the operator moves the current acquisition unit 1 closer to the overhead line through the insulated operating unit 3, the arc-shaped guide area 121 first contacts the cable. If an external force (such as pulling down or pushing up) is applied through the insulated operating unit 3, the cable will exert a squeezing force on the arc-shaped guide area 121. This force will cause the two clamps 12 to open outward against the elastic force of the compression spring 14, allowing the cable to smoothly enter the clamping area inside the clamp 12. When the external force is removed, the compression spring 14 returns to its original position, driving the clamps 12 to close automatically, completing the mounting of the current acquisition unit 1. When it is necessary to remove the clamps, an external force is applied in the opposite direction, and the arc-shaped guide area 121 is subjected to force again, causing the clamps 12 to open, thus removing the acquisition unit from the line and achieving automatic removal. The arc-shaped guide area 121 completely solves the problem of manually opening and closing the clamps 12 in existing acquisition devices. The clamps 12 can be automatically opened and closed by external force and the arc-shaped structure, which greatly simplifies the installation and removal process of the current acquisition unit 1 on the overhead line. Operators do not need to adjust the clamps 12 at close range. All actions can be completed by operating the insulated operation unit 3 from the ground, which further reduces labor intensity and operational risks. At the same time, the design of the arc-shaped guide area 121 to fit the cable can avoid scratching and damage to the cable insulation during operation, protect the original structure of the overhead line, reduce the potential for line faults caused by the detection operation, and improve the safety and reliability of the detection process.

[0063] In some embodiments, each of the two clamps 12 has a semi-circular magnetic ring 122 on its inner side. When the two semi-circular magnetic rings 122 are closed, they form a complete current-sensing magnetic ring for collecting line current signals. One clamp 12 has at least two V-shaped blocks 123 on its inner side, and the other clamp 12 has V-shaped grooves 124 corresponding to the V-shaped blocks 123 on its inner side. When the two clamps 12 are closed, the V-shaped blocks 123 are inserted into the V-shaped grooves 124 to achieve precise alignment of the two semi-circular magnetic rings 122. The V-shaped blocks 123 and the V-shaped grooves 124 together constitute the clamping area 125.

[0064] It should be noted that a semi-circular magnetic ring 122 is provided on the inner side of each of the two clamps 12. When the clamps 12 are closed, the two semi-circular magnetic rings 122 can be spliced ​​to form a complete current-sensing magnetic ring. This magnetic ring is made of a high-permeability material and can effectively sense the current signal in the overhead line and convert it into an electrical signal. At the same time, at least two V-blocks 123 are provided on the inner side of one of the clamps 12, and V-grooves 124 corresponding to the V-blocks 123 are provided on the inner side of the other clamp 12. When the compression spring 14 drives the two clamps 12 to close, the V-blocks 123 can be accurately inserted into the V-grooves 124. Through the positioning effect of the V-shaped structure, the coaxiality of the two semi-circular magnetic rings 122 is ensured during the closing process, avoiding magnetic gaps or misalignment. The complete current sensing magnetic ring formed by splicing two semi-circular magnetic rings 122 can improve the sensing efficiency and sensitivity of the current signal, ensuring effective acquisition of small leakage current signals. The cooperative structure of the V-block 123 and the V-groove 124 achieves precise positioning when the clamp 12 is closed from a mechanical perspective, completely solving the measurement error problem caused by the gap or misalignment of the magnetic ring docking in existing acquisition devices, and ensuring the accuracy and repeatability of current signal acquisition. The precise closure of the two semi-circular magnetic rings enables the current acquisition unit 1 to accurately detect the current of the transmission line, meeting the needs of high-precision leakage current detection for overhead lines in low-voltage distribution areas, and providing a reliable data foundation for subsequent leakage current calculation and fault diagnosis.

[0065] In some embodiments, the signal processing unit 4 further includes a display module, a storage module, and a communication module; the display module is used to display leakage current value, phase current value, three-phase imbalance, and line load parameters in real time; the storage module is used to store at least 1000 sets of detection data; the communication module includes a Bluetooth unit and a USB interface unit, used to transmit detection data to a mobile terminal or computer device.

[0066] It should be noted that a display module, a storage module, and a communication module are added to the signal processing unit 4. The display module uses a high-definition touchscreen color display, which can receive the leakage current value, each phase line current value, three-phase imbalance, and line load parameters calculated by the signal processing unit 4 in real time, and display them in intuitive numerical or waveform form for easy on-site reading by operators. The storage module uses a large-capacity Flash memory, capable of storing at least 1000 sets of detection data. Each set of data includes information such as detection time, line number, leakage current value, and each phase current value. The data retention period is no less than 10 years, supporting later data traceability. The communication module includes a Bluetooth unit and a USB interface unit. The Bluetooth unit can establish a wireless connection with mobile terminals, and the USB interface unit can establish a wired connection with computer equipment, realizing the transmission of detection data to external terminals. The display module allows operators to acquire test data on-site without additional equipment, avoiding data reading delays and errors and improving testing efficiency. The storage module's large-capacity data storage function can retain historical test data on overhead line leakage current, providing data support for analyzing leakage current trends and tracing fault causes, facilitating power maintenance personnel in developing long-term line maintenance plans. The communication module's dual wireless and wired connection methods support flexible transmission of test data to mobile terminals or computer devices. Subsequently, the data can be analyzed, organized, and test reports generated through terminal devices, improving the standardization and convenience of data management and meeting the digitalization needs of power system operation and maintenance.

[0067] Reference Figure 14 The second aspect of the present invention provides a method for detecting leakage current in overhead lines, comprising the following steps:

[0068] S1: The operator uses the insulation operation unit 3 to hang multiple current acquisition units 1 on each phase line and neutral line of the overhead line, so that the clamping structure of each current acquisition unit 1 clamps the corresponding line and acquires the current signal.

[0069] S2: Each of the current acquisition units 1 transmits the acquired current signal to the signal processing unit 4 through the signal transmission unit 2;

[0070] S3: The signal processing unit 4 acquires all the current signals through the built-in high-precision current transformer, calculates the vector sum of each current signal, and obtains the leakage current value of the overhead line based on the vector sum. The calculation formula for the leakage current value is: I0 = |I_A + I_B + I_C + I_N|, where I0 is the leakage current value, I_A, I_B, and I_C are the current signals of the three-phase lines A, B, and C, respectively, and I_N is the current signal of the neutral line.

[0071] S4: The signal processing unit 4 determines whether there is a leakage fault in the overhead line based on the leakage current value and the preset natural leakage current threshold range. If there is a leakage fault, the leakage fault point is located.

[0072] In practice, firstly, the operator uses the insulated operating unit 3 to attach multiple current acquisition units 1 to each phase and neutral line of the overhead line, causing the clamps 12 of each current acquisition unit 1 to automatically close and clamp the corresponding line, thus acquiring the current signal. Secondly, each current acquisition unit 1 transmits the acquired current signal stably to the signal processing unit 4 through the signal transmission unit 2. Then, the signal processing unit 4 simultaneously acquires all current signals through a built-in high-precision current transformer, calculates the vector sum of these current signals, and obtains the leakage current value of the overhead line according to the formula I0 = |I_A + I_B + I_C +I_N| (where I0 is the leakage current value, I_A, I_B, and I_C are the current signals of the three phases A, B, and C, respectively, and I_N is the current signal of the neutral line). Finally, the signal processing unit 4 compares the calculated leakage current value with the preset natural leakage current threshold range to determine whether there is a leakage fault in the overhead line. If a fault exists, the fault point is further located. This detection method is based on the aforementioned detection device, inheriting its advantages of adaptability to large-spacing overhead lines and ease of operation. It can complete leakage current detection without power outages on overhead lines, avoiding disruption to users' normal power supply. The leakage current value is calculated using vector sum formulas, conforming to the measurement principle of leakage current for overhead lines in low-voltage distribution areas, ensuring the accuracy of leakage current calculations. Furthermore, this method combines leakage current detection with fault location, not only determining whether a line is leaking current but also pinpointing the fault location. This solves the problem of existing detection methods that can only detect leakage current but cannot locate the fault point, significantly reducing the inspection time and workload of power maintenance personnel and improving the efficiency of handling leakage faults.

[0073] In some embodiments, step S1, which involves mounting the plurality of current acquisition units 1 onto each phase and the neutral line of an overhead line, specifically includes:

[0074] S11: The connection interface 113 between the insulation operation unit 3 and the current acquisition unit 1 is detachably connected, and the signal transmission unit 2 is connected to the signal interface 112 of the current acquisition unit 1.

[0075] S12: The operator holds the insulating operation unit 3 and brings the arc-shaped guide area 121 of the current acquisition unit 1 close to the target line;

[0076] S13: Pull the insulation operation unit 3 away from the line, so that the two clamps 12 open outward against the elastic force of the compression spring 14 until the line enters the U-shaped mounting area 111; S14: Release the insulation operation unit 3, the compression spring 14 resets and drives the two clamps 12 to close, the V-shaped block 123 is inserted into the V-shaped groove 124, and the semi-circular magnetic ring 122 is precisely aligned, completing the mounting.

[0077] It should be noted that the mounting steps for the current acquisition unit 1 are detailed, specifically including: First, the connection interface 113 between the insulation operation unit 3 and the current acquisition unit 1 is detachably connected via a threaded structure to ensure a secure connection. Simultaneously, one end of the signal transmission unit 2 is inserted into the signal interface 112 of the current acquisition unit 1, and the other end is connected to the corresponding interface of the signal processing unit 4, completing the assembly of each component. Second, the operator holds the bottom of the insulation operation unit 3 and places the arc-shaped guide area 121 of the current acquisition unit 1 close to the target overhead line, ensuring that the arc-shaped guide area 121 is aligned with the line. Third, the insulation operation unit 3 is slowly pulled away from the line. The arc-shaped guide area 121 is compressed by the line, causing the two clamps 12 to open outwards against the spring force of the compression spring 14 until the line is completely inside the U-shaped attachment area 111 of the clamps 12. Fourth, the insulation operation unit 3 is released, and the compression spring 14 resets, driving the two clamps 12 to automatically close. At this time, the V-shaped clamps on the clamps 12... The shaped block 123 is inserted into the V-groove 124, and the semi-circular magnetic ring 122 is precisely aligned, completing the mounting of a single current acquisition unit 1. Repeating the above steps completes the mounting of all acquisition units. This detailed design of the mounting process provides operators with a standardized operating procedure, avoiding improper installation of acquisition units or damage to the wiring due to non-standard operation. The threaded connection between the insulated operating unit 3 and the acquisition unit, and the interface connection of the signal transmission unit 2, ensure the connection stability of each component during operation, reducing the risk of signal transmission interruption or acquisition unit detachment due to loose connections. The cooperation between the arc-shaped guide area 121 and the spring drive eliminates the need for manual adjustment of the clamp 12 during the mounting process; it can be completed simply by pulling and releasing the insulated operating unit 3, further simplifying the operation, lowering the technical threshold for operators, and ensuring that operators of varying skill levels can complete the mounting operation efficiently and safely.

[0078] Reference Figures 10 to 12 In some embodiments, step S4, locating the leakage fault point, specifically includes:

[0079] S41: Select two measurement points on the leakage current branch line, and mark them as measurement point 1 and measurement point 2 respectively. Measurement point 1 is close to the transformer output terminal, and measurement point 2 is far away from the transformer output terminal.

[0080] S42: At measurement point 1 and measurement point 2, the current signals of each phase and the neutral line are collected by the current acquisition unit 1, and the leakage current vector sum of the two measurement points is calculated and denoted as I_i1 and I_i2 respectively.

[0081] S43: Compare the magnitudes of I_i1 and I_i2: If I_i1≈I_i2, it is determined that there is no leakage fault between the two measurement points, and new measurement points are selected in the direction away from the transformer, repeating steps S42-S43; if I_i1>I_i2, it is determined that there is a leakage fault between the two measurement points, and new measurement points are selected between the two measurement points using the binary search method, repeating steps S42-S43 until the specific fault point is located.

[0082] It should be noted that the steps for locating leakage faults are detailed and include: First, select two measurement points on the branch line where a leakage fault has been identified. Measurement point 1 is close to the transformer outlet, and measurement point 2 is far from the transformer outlet. The distance between the two points is set to 50-100 meters according to the line length for easy on-site operation. Second, install current acquisition units 1 at measurement points 1 and 2 respectively according to the above mounting steps to collect the current signals of each phase and the neutral line. The leakage current vector sum of the two measurement points is calculated by the signal processing unit 4 and denoted as I_i1 and I_i2 respectively. Third, compare the magnitudes of I_i1 and I_i2: If the difference between I_i1 and I_i2 does not exceed 5%, it is determined that there is no leakage fault between the two measurement points, and the leakage current originates from the line far from measurement point 2. A new measurement point needs to be selected in the direction away from the transformer, and the above measurement and comparison steps need to be repeated. If I_i1 is greater than I_i2... If the difference exceeds 5%, a leakage fault is determined to exist between the two measurement points. A bisection method is used to select a new measurement point between the two points, and the leakage current vector sum at this new measurement point is calculated. This comparison process is repeated until the specific fault point is located, ensuring the fault location accuracy is controlled within 5 meters. This fault location method is based on the variation law of the leakage current vector sum. Through two-point comparison and bisection approximation, it can quickly narrow down the search range of the fault point, avoiding the problem of blind inspection in traditional fault location methods, significantly shortening the fault location time, and improving the efficiency of handling leakage faults. The reasonable setting of the measurement point spacing and the clear difference judgment standard provide operators with standardized positioning basis, reducing positioning errors caused by subjective judgment differences. Furthermore, this method does not require disassembly or power outage of the line; fault location can be completed solely through external detection, protecting the original structure of the line and reducing additional risks during fault handling. It is suitable for leakage fault location scenarios in various branch lines.

[0083] In some embodiments, in step S4, the preset natural leakage current threshold range is 10mA to 100mA; when the leakage current value of the overhead line exceeds 1.5 to 2 times the natural leakage current threshold range, or is continuously higher than 300mA without a clear cause of equipment interference, it is determined that there is a leakage fault in the overhead line.

[0084] In practice, based on the actual operating characteristics of overhead lines in low-voltage distribution areas, a preset natural leakage current threshold range is established: for dry overhead lines with good insulation, the natural leakage current threshold range is set to 1mA to 10mA; for damp, older overhead lines with long service lives, the natural leakage current threshold range is set to 50mA to 300mA; and for general scenarios, the natural leakage current threshold range is set to 10mA to 100mA. During the detection process, the signal processing unit 4 compares the calculated leakage current value with the corresponding natural leakage current threshold range: if the leakage current value exceeds 1.5 to 2 times the threshold range, or if the leakage current value is consistently higher than 300mA and interference factors caused by capacitive coupling of electronic equipment such as frequency converters and switching power supplies are excluded, then it is determined that there is a leakage fault in the overhead line; if the leakage current value is within the natural leakage current threshold range, then it is determined that there is no leakage fault in the line, and it is only normal current leakage. The setting of this natural leakage current threshold range fully considers the impact of different environmental conditions and line states on the natural leakage current of overhead lines, avoiding the problem of misjudgment or missed judgment caused by using a single threshold. The clear fault judgment criteria provide operators with an objective and unified basis for judgment, reducing judgment errors caused by differences in experience. At the same time, the elimination of interference factors from electronic equipment further improves the accuracy of fault judgment, ensuring that the subsequent fault location process is only initiated when there is a real leakage fault in the line, avoiding unnecessary maintenance operations, reducing the cost and workload of power maintenance, and improving operation and maintenance efficiency.

[0085] In some embodiments, step S5 is further included: uploading the detected leakage current value, phase current value, fault location information and detection time to a mobile terminal or computer device through the communication module of the signal processing unit 4 to generate a leakage current detection report. The detection report includes the fault line number, fault point distance, leakage current peak value and suggested repair plan.

[0086] It should be noted that a data upload and report generation step is added at the end of the testing process: First, the data such as leakage current value, current value of each phase line, fault location information, and testing time obtained during the testing process are transmitted to the mobile terminal or computer device through the communication module (Bluetooth unit or USB interface unit) of signal processing unit 4; then, the mobile terminal or computer device organizes and analyzes the uploaded data according to the preset report template, and automatically generates an overhead line leakage current detection report containing the fault line number, fault distance, leakage current peak value, fault type (such as insulation damage, foreign object connection), and suggested maintenance plan (such as replacing insulation, removing foreign objects); finally, the operator can formulate a targeted maintenance plan based on the generated detection report to guide the subsequent leakage fault handling work. The data upload function enables efficient transmission of test data from equipment to terminals, avoiding errors and omissions caused by manual data recording and ensuring data integrity and accuracy. The automatically generated test reports contain key information needed for fault handling, providing power maintenance personnel with clear and standardized maintenance guidance and avoiding unreasonable maintenance plans due to incomplete information. At the same time, the retention of test reports can form the operation and maintenance archives of overhead lines, providing data support for subsequent regular line inspections, condition assessments, and the formulation of long-term maintenance plans, promoting the standardization and digitalization of power operation and maintenance work, and improving the overall operation and maintenance management level.

[0087] Reference Figure 5 A third aspect of the present invention provides a computer device including a memory and a processor, the memory storing a computer program and the processor being configured to execute the computer program to implement the overhead line leakage current detection method as described above.

[0088] In some embodiments, the overhead line leakage current detection method in the above embodiments can be implemented by a computer device, which includes at least one processor, a communication bus, a memory, and at least one communication interface.

[0089] A processor can be a general-purpose central processing unit (CPU) or an application-specific integrated circuit (ASIC).

[0090] A communication bus can be used to transmit information between the aforementioned components.

[0091] The memory can be read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions, random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, universal optical discs, Blu-ray discs, etc.), magnetic disks or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited to these. The memory can exist independently and be connected to the processor via a communication bus. The memory can also be integrated with the processor.

[0092] The memory stores program code for executing the solution of this application, and its execution is controlled by a processor. The processor executes the program code stored in the memory. The program code may include one or more software modules. In the above embodiments, the overhead line leakage current detection method can be implemented by a processor and one or more software modules in the program code in the memory.

[0093] A communication interface is a device that uses any transceiver or similar device to communicate with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.

[0094] In a specific implementation, as one example, a computer device may include multiple processors, each of which may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. Here, a processor may refer to one or more devices, circuits, and / or processing cores used to process data (e.g., computer program instructions).

[0095] The aforementioned computer device can be a general-purpose computer device or a special-purpose computer device. In specific implementations, the computer device can be a desktop computer, a portable computer, a network server, a handheld digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, a communication device, or an embedded device. This application does not limit the type of computer device.

[0096] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the overhead line leakage current detection method as described above.

[0097] Reference Figures 1 to 4 as well as Figures 6 to 14 To provide a clearer understanding of the invention, the following description further illustrates the invention:

[0098] An overhead line leakage current detection device includes a current acquisition unit 1, a signal transmission unit 2, an insulation operation unit 3, and a signal processing unit 4. The units work together to achieve accurate acquisition, transmission, calculation, and display of overhead line leakage current.

[0099] Current acquisition unit 1

[0100] The current acquisition unit 1 is provided in multiple units, preferably four, corresponding to the A, B, and C phase lines and the neutral line (N line) of the overhead line, respectively, for one-to-one acquisition of the current signal of each line. Each current acquisition unit 1 includes a housing 11, two clamps 12, two rotating shafts 13, and two compression springs 14.

[0101] Housing 11: Made of high-strength insulating material (such as epoxy resin), with a U-shaped mounting area 111, a signal interface 112, and a connection interface 113 on its surface. The curvature of the U-shaped mounting area 111 matches the outer diameter of the overhead line cable 5 for pre-fixing the acquisition unit; the signal interface 112 is a waterproof interface for connecting the signal transmission unit 2; the connection interface 113 has an internal thread for detachable connection with the insulated operation unit 3.

[0102] Clamps 12: Two clamps 12 are symmetrically mounted on both sides of the U-shaped abutment area 111 of the housing 11 via a rotating shaft 13, and can rotate around the rotating shaft 13. The end of the clamp 12 away from the rotating shaft 13 is provided with an arc-shaped guide area 121. The arc design of the guide area allows the clamp 12 to open automatically under external pulling force. A semi-circular magnetic ring 122 is provided on the inner side of the clamp 12. When the two clamps 12 are closed, they form a complete ring current transformer, which is used to sense the line current and convert it into an electrical signal.

[0103] Clamping structure: To ensure precise alignment of the semicircular magnetic rings 122 and reduce magnetic gap error, one clamp 12 has two V-blocks 123 on its inner side, and the other clamp 12 has two V-grooves 124 that fit the V-blocks 123 on its inner side. When the clamps 12 are closed, the V-blocks 123 are inserted into the V-grooves 124 to achieve mechanical positioning, ensuring that the coaxiality error of the two semicircular magnetic rings 122 is ≤0.1mm, which significantly improves the current acquisition accuracy.

[0104] Compression spring 14: It is sleeved on the rotating shaft 13, and its two ends abut against the housing 11 and the clamp 12 respectively. In the initial state, it drives the two clamps 12 to close. When an external force is applied to pull the insulating operating unit 3, the clamps 12 open against the spring force. After the external force is removed, the spring returns to its original position, realizing automatic closure.

[0105] Signal transmission unit 2

[0106] The signal transmission unit 2 uses shielded signal cables (such as double-layer copper mesh shielded cables). One end is connected to the signal interface 112 of each current acquisition unit 1, and the other end is connected to the signal processing unit 4. The shielding structure can effectively resist outdoor electromagnetic interference (such as electromagnetic radiation from the transmission line itself and interference from surrounding electronic equipment), ensuring a signal-to-noise ratio ≥60dB during current signal transmission and avoiding signal distortion. The length of the signal cable can be adjusted according to the height of the overhead line, preferably 5-10 meters, to meet the detection needs of most low-voltage distribution area overhead lines.

[0107] Insulation Operation Unit 3

[0108] The insulated operating unit 3 is a telescopic insulated rod made of fiberglass reinforced plastic (FRP), possessing high strength and high insulation (insulation resistance ≥100MΩ, conforming to IEC 61326 standard). The insulated rod has a retracted length of 1000mm (easy to carry) and an extended length of 4300mm (suitable for operation on overhead lines at heights of 3-5 meters). The top of the rod has an external thread that mates with the connection interface 113 of the current acquisition unit 1, enabling a detachable connection. Operators can attach and detach the acquisition unit by holding the bottom of the insulated rod, eliminating the need for working at heights and significantly improving operational safety.

[0109] The signal processing unit 4 is a portable concentrator, which integrates a high-precision current transformer (accuracy class 0.2), a microprocessor (such as an ARM Cortex-M4 core chip), a display module, a storage module, and a communication module.

[0110] High-precision current transformer: Simultaneously clamps four signal transmission lines to acquire current signals from phases A, B, C, and N. Through electromagnetic induction, these current signals are converted into measurable low-voltage signals for subsequent vector sum calculations. Leakage current is detected by the high-precision current transformer, which uses a permalloy magnetic ring and can detect leakage currents less than 0.1mA.

[0111] Microprocessor: Samples and amplifies the low-voltage signal output from the transformer (adjustable amplification factor, range 100-1000 times), converts the analog signal into a digital signal through an ADC module (16-bit resolution), and then calculates the leakage current value according to the formula I0 = |I_A + I_B + I_C + I_N| (where I_A, I_B, I_C, and I_N are the vector values ​​of the current in each phase, including amplitude and phase information, and the magnitude of the vector sum is the leakage current); at the same time, it can calculate the three-phase unbalance (formula β = (I_max - I_min) / I_avg × 100%, where I_max is the maximum value of the three-phase current, I_min is the minimum value, and I_avg is the average value) and line load parameters.

[0112] Display module: It adopts a 7-inch touch color screen with a resolution of 1280×720. It can display the leakage current value (unit: mA / A), the current value of each phase, the three-phase imbalance, the detection time and the battery level in real time. The interface is intuitive and easy for operators to read.

[0113] Storage module: It adopts Flash memory and can store 1000 sets of test data. Each set of data includes test time, line number, leakage current value, current value of each phase and fault identifier. The data retention time is ≥10 years, which is convenient for subsequent traceability and analysis.

[0114] Communication module: Includes Bluetooth unit (supports Bluetooth 5.0, transmission distance ≤10 meters) and USB Type-C interface, which can transmit detection data to mobile APP ("Overhead Line Leakage Location Assistant") or computer to realize real-time data viewing, report generation and printing.

[0115] A method for detecting leakage current in overhead lines, the detection method of the present invention is based on the above-mentioned device, and includes the steps of mounting a data acquisition unit, transmitting signals, calculating leakage current, locating fault points, and uploading data, as detailed below:

[0116] Step S1: Install current acquisition unit 1

[0117] S11: Preparation: Check the status of each unit to ensure that the clamp 12 of the current acquisition unit 1 is properly closed, the signal transmission unit 2 is undamaged, the insulation performance of the insulation operation unit 3 is good (which can be tested with an insulation resistance meter), and the signal processing unit 4 has sufficient power (battery life ≥ 10 hours). S12: Connection assembly: Screw the external thread at the top of the insulation operation unit 3 into the connection interface 113 of the current acquisition unit 1 (tightening torque ≤ 5 N·m, to avoid damaging the interface), insert one end of the signal transmission unit 2 into the signal interface 112 of the current acquisition unit 1, and connect the other end to the corresponding interface of the signal processing unit 4. S13: Mounting Operation: The operator stands in a safe area on the ground, holds the bottom of the insulated operating unit 3, and places the arc-shaped guide area 121 of the current acquisition unit 1 close to the target line (e.g., phase A); slowly pull the insulated operating unit 3 away from the line. The arc-shaped guide area 121 is squeezed by the line, causing the two clamps 12 to open outward against the elastic force of the compression spring 14 until the line is completely in the U-shaped mounting area 111; release the insulated operating unit 3, the compression spring 14 returns to its original position, driving the clamps 12 to close, the V-shaped block 123 to insert into the V-shaped groove 124, and the semi-circular magnetic ring 122 to precisely align, completing the mounting of a single acquisition unit. S14: Repeat Operation: Following the steps of S13, mount the remaining 3 current acquisition units 1 to phase B, phase C, and the neutral line (N line) respectively, ensuring that each acquisition unit has good contact with the line and is not loose.

[0118] Step S2: Transmitting Current Signals The semi-circular magnetic ring 122 of each current acquisition unit 1 senses the line current and converts it into a weak electrical signal (amplitude range 10-100mV), which is transmitted to the signal processing unit 4 through the shielded signal line of the signal transmission unit 2. During the transmission process, the shielding layer effectively isolates electromagnetic interference and ensures that the signal transmission error is ≤0.5%.

[0119] Step S3: Calculate the leakage current value. S31: The high-precision current transformer in signal processing unit 4 receives four current signals and converts them into low-voltage signals with a uniform range (e.g., 0-5V). S32: The microprocessor samples the low-voltage signal through the ADC module (sampling frequency 500Hz, meeting the sampling requirements of 50 / 60Hz power frequency signals) and performs filtering (using an IIR low-pass filter with a cutoff frequency of 100Hz to remove high-frequency noise). S33: Based on the sampled amplitude and phase of each phase current, calculate the vector sum using the formula I0 = |I_A + I_B + I_C + I_N|. Obtain the leakage current value; for example, if I_A=5A∠0°, I_B=5A∠120°, I_C=5A∠240°, I_N=0A, then the vector sum is 0A, the leakage current I0=0A, and it is determined that there is no leakage in the line; if I_N=0.5A∠0°, then the vector sum is 0.5A, the leakage current I0=0.5A, and further judgment is needed to determine whether it is a fault.

[0120] Step S4: Fault Diagnosis and Location S41: Setting the Natural Leakage Current Threshold: Based on the characteristics of overhead lines in low-voltage distribution areas, the preset natural leakage current threshold range is 10mA~100mA (1mA~10mA for dry, well-insulated lines, 50mA~300mA for damp, old lines); when the detected leakage current value exceeds 1.5 to 2 times this threshold range, or remains above 300mA and capacitive coupling interference from inverters, switching power supplies, and other equipment is excluded, a leakage fault is determined to exist in the line. S42: Fault Location (Taking a branch line as an example):

[0121] Select measurement points: Select two measurement points on the leakage branch line. Measurement point 1 is close to the transformer outlet (referred to as "near end"), and measurement point 2 is far from the transformer outlet (referred to as "far end"). The distance between the two points is preferably 50-100 meters (for ease of operation).

[0122] Measurement vector sum: At measurement point 1 and measurement point 2, current signals are collected according to steps S1-S3 respectively, and the leakage current vector sums I_i1 (near end) and I_i2 (far end) of the two points are calculated.

[0123] Determine the fault range:

[0124] If I_i1≈I_i2 (error ≤5%): This indicates that there is no leakage fault between the two measurement points. The leakage current originates from the line at the far end of measurement point 2. It is necessary to select measurement point 3 (located at the far end of measurement point 2) in the direction away from the transformer and repeat the measurement and comparison.

[0125] If I_i1 > I_i2 (difference > 5%): This indicates that there is a leakage fault between the two measurement points (because the leakage current at the fault point will cause the vector sum at the far end to decrease). Use the bisection method to select measurement point 4 between measurement point 1 and measurement point 2, and calculate I_i4. If I_i1 > I_i4, then the fault point is located between measurement point 1 and 4, otherwise it is located between 4 and 2. Repeat until the specific fault point is located (error ≤ 5 meters).

[0126] S43: Special scenario handling (T-connected branch line, neutral line repeated grounding):

[0127] T-connected branch line: Select measurement point 1 (near end of main line), measurement point 2 (far end of main line), and measurement point 3 (far end of T-connected branch line). If I_i3 is very small (≤ natural leakage current threshold) and I_i1≈I_i2, then there is no fault in the T-connected branch line, and the fault is between main line 1 and 2; if I_i3 is very large, then the fault is at the far end of T-connected branch line 3.

[0128] Repeated grounding of neutral line: Select measurement point 1 (before grounding), measurement point 2 (after grounding), and measurement point 3 (neutral line grounding end). If I_i3 is very small and I_i1 > I_i2, then the neutral line is loosely connected, and the fault is between 1 and 2. If I_i3 is very large, then the fault is between 1 and 2.

[0129] Step S5: Data Upload and Report Generation

[0130] The detection data (including leakage current value, current of each phase, fault location, and detection time) can be uploaded to the terminal device via Bluetooth module of signal processing unit 4 or via USB interface to a computer. The terminal device automatically generates an "Overhead Line Leakage Detection Report" based on the uploaded data. The report includes the fault line number, distance to the fault point, peak leakage current, fault type (such as insulation damage, foreign object bridging) and suggested repair solutions (such as replacing insulation and removing foreign objects), which helps power maintenance personnel to formulate maintenance plans.

[0131] Implementation Case: Leakage Current Measurement and Location in Distribution Transformer Areas

[0132] First, check the total leakage current of the transformer area and the leakage current of the branch lines to determine which branch line has a leakage fault. Then, check the branch lines segment by segment from front to back to locate the leakage fault point.

[0133] The detector is equipped with three types of current clamps. The high-precision current clamp and the flexible current clamp are used to collect the total leakage current of the transformer area and the leakage current of the branch circuit, while the hook-type current clamp is used to locate the leakage fault point of the overhead line.

[0134] The high-precision current clamp is made with a permalloy core and double-layer shielding, which has the advantages of strong anti-interference ability, high measurement accuracy, and accurate measurement of weak leakage current. It is recommended to use the high-precision current clamp when testing leakage current to ensure measurement accuracy.

[0135] Flexible current clamps offer advantages such as lightweight coils and large diameters. However, due to the characteristics of Rogowski coils, they exhibit significant errors when measuring small leakage currents. If a flexible current clamp must be used due to environmental reasons, the flexible coil should be repeatedly wound around the conductor being tested multiple times before being closed to improve test resolution. The actual current is equal to the instrument's displayed value divided by the number of turns of the flexible coil. For example, if it is wound 3 times, the instrument displays 7.5A, but the actual current is 7.5 / 3 = 2.5A. This instrument allows setting the number of turns; once set, the displayed value is the actual value, facilitating the management of historical data.

[0136] Measure the total leakage current of the transformer area and the leakage current of the branch lines.

[0137] Use a high-precision current clamp or flexible current clamp to measure the total leakage current and branch line leakage current of the transformer substation at the neutral point grounding wire. When measuring the branch line leakage current, cables A, B, C, and N must be clamped simultaneously. If the leakage current value is greater than the natural leakage current value, it indicates that there is a leakage fault in that branch line. Figure 6 As shown.

[0138] Location of leakage fault:

[0139] For branch lines with leakage faults, follow these steps to locate the fault point. The detector is equipped with four hook-type current clamps, signal connection cables, and an insulating rod for locating leakage fault points. It can also measure the line's load current and three-phase imbalance.

[0140] Overhead line leakage vector and measurement principle:

[0141] Four hook-type current clamps are mounted on the overhead line to collect the currents of lines A, B, C, and N respectively. These currents are then connected to the main unit via signal lines. The main unit has a built-in current transformer and simultaneously clamps the four current signal lines (A, B, C, and N) to measure the leakage vector sum. For example... Figure 7 As shown.

[0142] Step 1: Install hook-type current clamps

[0143] First, screw the four hook-type current clamp threaded interfaces into the insulating rod. Then, insert the signal wires into the current clamp and the host interface, respectively. Next, hang the current clamps on the corresponding A, B, C, and N lines. For example... Figure 8 As shown. Note that the current clamp must be installed in the direction of current flow. After the current clamp is installed, press the power button on the main unit. The main unit will display the load currents A, B, and C, the neutral current N, the three-phase unbalance, and the leakage vector sum.

[0144] The hook-type current clamp features a hook structure and an automatic clamping and retraction mechanism. During installation, place the guide area of ​​the current clamp close to the cable, pull down the insulating rod, and the current clamp will automatically clamp into the cable. After testing, push the insulating rod upward, and the current clamp will automatically retract from the cable. Figure 9 As shown. During the test, the current clamp can remain attached to the cable without support, making the test simple and quick, greatly reducing the workload of the testers and improving work efficiency.

[0145] Step 2: Locating the Leakage Fault Point

[0146] Measurements are taken along the branch lines starting from the transformer outlet. By comparing the leakage vector sum, the location of the leakage fault is determined. The binary search method can be used to quickly approximate the fault point.

[0147] Branch line leakage fault location: such as Figure 10 As shown, the leakage vector sum at two points on the line is measured, and the leakage vector sum at the two points is compared to determine the leakage fault point.

[0148] Leakage vector sum comparison illustrate Ii1≈Ii2 There was no leakage fault between the two measurement points, so we continued to investigate after measurement point 2. Ii1>Ii2 There is a leakage fault point between the two measurement points. Ii1<Ii2 Abnormal measurement results

[0149] Note: Ii1 is the leakage vector sum at measurement point 1, and Ii2 is the leakage vector sum at measurement point 2.

[0150] T-junction branch line leakage fault location: For T-junction branches, three cable points need to be measured. By comparing the leakage vector sum of the three measurement points, the leakage fault point can be determined. Figure 11 As shown.

[0151] Leakage vector sum comparison illustrate Ii3 is very small, Ii1≈Ii2 There was no leakage fault in the T-connection branch. There was no leakage fault between the two measurement points 1 and 2. Continue to check after measurement point 2. Ii3 is very small, Ii1 > Ii2 There is no leakage fault in the T-connection branch, but there is a leakage fault point between measurement point 1 and measurement point 2. Ii3 is very big There is a leakage fault on the T-junction branch, which needs to be investigated after measurement point 3.

[0152] Note: Ii1 is the leakage vector sum of measurement point 1, Ii2 is the leakage vector sum of measurement point 2, and Ii3 is the leakage vector sum of measurement point 3.

[0153] Fault location in a branch line with repeated neutral grounding: For transformer substations with repeated neutral grounding, measurements are taken before and after the repeated grounding point. For example... Figure 12 As shown.

[0154] Leakage vector sum comparison illustrate Ii3 is very small, Ii1≈Ii2 There was no leakage fault between measurement points 1 and 2. Continue the investigation towards measurement point 2. Ii3 is very small, Ii1 > Ii2 The neutral wire is loosely connected, and there is a leakage fault between measurement point 1 and measurement point 2. Ii3 is very big There is a leakage fault point between measurement point 1 and measurement point 2.

[0155] Note: Ii1 is the leakage vector sum of measurement point 1, Ii2 is the leakage vector sum of measurement point 2, and Ii3 is the neutral grounding current.

[0156] Step 3: Remove the current clamp

[0157] After confirming the measurement results, push the insulating rod upwards to remove the hook-type current clamp from the cable. Unscrew the insulating rod and place the current clamp and signal line inside the instrument box. The test is now complete. Note: The hook-type current clamp is a precision instrument and must be handled with care and stored properly.

[0158] Other leakage current fault measurements: High-precision current clamps can be used to measure leakage current in electromechanical equipment, potential grounding faults in walls, and grounding current in electromechanical equipment. For example... Figure 13 As shown.

[0159] Transformer leakage fault quick location assistant APP

[0160] The locator is equipped with a "Quick Location Assistant for Leakage Faults in Transformer Areas" APP. By installing the APP on a mobile terminal and communicating with the main unit via Bluetooth, it can assist operators in quickly diagnosing leakage faults.

[0161] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A leakage current detection device for overhead lines, characterized in that, include: Multiple current acquisition units are used to acquire the current signals of each phase line and the neutral line in the overhead line respectively. The current acquisition unit has an openable and closable clamping structure to achieve detachable connection with the line. The signal transmission unit is connected at one end to each of the current acquisition units and is used to transmit the current signal acquired by the current acquisition unit. An insulated operating unit is detachably connected to each of the current acquisition units and is used by operators to perform overhead line installation and removal operations on the current acquisition units on the ground or in a safe area. A signal processing unit is connected to the other end of the signal transmission unit. The signal processing unit has a built-in high-precision current transformer. The high-precision current transformer is used to simultaneously acquire each of the current signals and measure their vector sum. The signal processing unit is also used to calculate the leakage current value of the overhead line based on the vector sum.

2. The overhead line leakage current detection device according to claim 1, characterized in that: The current acquisition unit includes a housing, two rotatable clamps, two rotating shafts, and two compression springs. The housing has a U-shaped mounting area, a signal interface, and a connection interface. The signal interface is connected to the signal transmission unit, and the connection interface is detachably connected to the insulation operation unit. The U-shaped mounting area is used to pre-mount the current acquisition unit onto an overhead line. The two clamps are symmetrically mounted on both sides of the U-shaped mounting area of ​​the housing via the rotating shafts. The compression springs are sleeved on the rotating shafts, with their ends abutting against the housing and the clamps, respectively, to drive the two clamps to automatically close and clamp the line.

3. The overhead line leakage current detection device according to claim 2, characterized in that: The clamp is provided with an arc-shaped guide area at the end away from the rotating shaft. The arc-shaped guide area is used to make the two clamps open outward against the elastic force of the compression spring when the insulation operation unit applies external force, so as to realize the automatic clamping and automatic withdrawal of the current acquisition unit from the overhead line.

4. The overhead line leakage current detection device according to claim 2, characterized in that: Each of the two clamps has a semi-circular magnetic ring on its inner side. When the two semi-circular magnetic rings are closed, they form a complete current-sensing magnetic ring for collecting line current signals. One of the clamps has at least two V-shaped blocks on its inner side, and the other clamp has V-shaped grooves on its inner side that correspond one-to-one with the V-shaped blocks. When the two clamps are closed, the V-shaped blocks are inserted into the V-shaped grooves to achieve precise docking of the two semi-circular magnetic rings.

5. The overhead line leakage current detection device according to claim 1, characterized in that: The signal processing unit further includes a display module, a storage module, and a communication module; the display module is used to display leakage current value, phase current value, three-phase imbalance, and line load parameters in real time; the storage module is used to store at least 1000 sets of detection data; the communication module includes a Bluetooth unit and a USB interface unit, used to transmit detection data to a mobile terminal or computer device.

6. A method for detecting leakage current in overhead lines, applied to the overhead line leakage current detection device as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: The operator uses the insulation operation unit to hang multiple current acquisition units on each phase line and neutral line of the overhead line, so that the clamping structure of each current acquisition unit clamps the corresponding line and acquires the current signal. S2: Each of the current acquisition units transmits the acquired current signal to the signal processing unit through the signal transmission unit; S3: The signal processing unit acquires all the current signals through the built-in high-precision current transformer, calculates the vector sum of each current signal, and obtains the leakage current value of the overhead line based on the vector sum. The calculation formula for the leakage current value is: I0 = |I_A + I_B + I_C + I_N|, where I0 is the leakage current value, I_A, I_B, and I_C are the current signals of the three-phase lines A, B, and C, respectively, and I_N is the current signal of the neutral line. S4: The signal processing unit determines whether there is a leakage fault in the overhead line based on the leakage current value and the preset natural leakage current threshold range. If there is a leakage fault, the leakage fault point is located.

7. The overhead line leakage current detection method according to claim 6, characterized in that: In step S1, the step of mounting the multiple current acquisition units onto each phase and the neutral line of the overhead line specifically includes: S11: The connection interface between the insulation operation unit and the current acquisition unit is detachably connected, and the signal transmission unit is connected to the signal interface of the current acquisition unit; S12: The operator holds the insulating operating unit and brings the arc-shaped guide area of ​​the current acquisition unit close to the target line; S13: Pull the insulation operation unit away from the line, so that the two clamps open outward against the spring force of the compression spring until the line enters the U-shaped mounting area; S14: Release the insulation operation unit, the compression spring resets and drives the two clamps to close, the V-block is inserted into the V-groove, and the semi-circular magnetic ring is precisely aligned to complete the mounting.

8. The overhead line leakage current detection method according to claim 6, characterized in that: In step S4, locating the leakage fault point specifically includes: S41: Select two measurement points on the leakage current branch line, and mark them as measurement point 1 and measurement point 2 respectively. Measurement point 1 is close to the transformer output terminal, and measurement point 2 is far away from the transformer output terminal. S42: At measurement point 1 and measurement point 2, the current signals of each phase and the neutral line are collected by the current acquisition unit, and the leakage current vector sum of the two measurement points is calculated and denoted as I_i1 and I_i2 respectively; S43: Compare the magnitudes of I_i1 and I_i2: If I_i1≈I_i2, it is determined that there is no leakage fault between the two measurement points, and new measurement points are selected in the direction away from the transformer, repeating steps S42-S43; if I_i1>I_i2, it is determined that there is a leakage fault between the two measurement points, and new measurement points are selected between the two measurement points using the binary search method, repeating steps S42-S43 until the specific fault point is located.

9. The overhead line leakage current detection method according to claim 6, characterized in that: In step S4, the preset natural leakage current threshold range is 10mA to 100mA; when the leakage current value of the overhead line exceeds 1.5 to 2 times the natural leakage current threshold range, or is continuously higher than 300mA without a clear cause of equipment interference, it is determined that there is a leakage fault in the overhead line.

10. The overhead line leakage current detection method according to claim 6, characterized in that: The method also includes step S5: uploading the detected leakage current value, phase current value, fault location information and detection time to a mobile terminal or computer device through the communication module of the signal processing unit to generate a leakage current detection report. The detection report includes the fault line number, fault point distance, leakage current peak value and suggested repair plan.

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