Detection device for low-voltage transformer area of power distribution network

Abstract

A power distribution network low-voltage transformer area detection device provided by the present invention comprises two sets of detection units used for different detection positions, each set of detection unit comprises three grounding rods, and each grounding rod is in contact with cable cores of different phase cables in a detection area through cable puncture. One of the three grounding rods is a main grounding rod for installing the signal processing unit, the signal processing unit of the main grounding rod is connected with the other two grounding rods through wires, and during detection, the puncture structure of the grounding rod is in direct contact with a cable core and transmits a line three-phase voltage signal to the signal processing unit in real time through the wires; the signal processing unit is used for receiving and processing a voltage signal transmitted by the grounding rod puncture structure; when transformer area detection is carried out, the two sets of detection unit groups are arranged at the two ends of a suspected low-voltage transformer area respectively, and voltage data of circuits at the two ends of the suspected low-voltage transformer area are collected, uploaded and compared at the same time, so that whether the suspected low-voltage transformer area is a low-voltage transformer area or not is judged; the monitoring accuracy can be improved, and the processing efficiency of the low-voltage problem is improved.

Description

Technical Field

[0001] This invention relates to the field of power grid operation and maintenance technology, and in particular to a detection device for low-voltage distribution areas in a distribution network. Background Technology

[0002] In my country, low- and medium-voltage rural power distribution networks mostly adopt a radial network structure. Due to their low construction costs and ease of initial maintenance, they were well-suited to the early, low-load, and dispersed electricity demands of rural areas. However, they suffer from limitations such as single-path power supply and wide-ranging fault impacts. A severe mismatch between power supply distribution and load demand, coupled with a surge in demand forcing a sharp increase in the load on the distribution network, has led to continuous overload operation of transformers in some remote areas, exacerbating line voltage losses. Furthermore, the long power supply radius and small wire diameter of early-installed lines have resulted in low voltage issues at the end of the lines—voltage values ​​often fall below the national standard of 200V (rated 220V), and in some extreme cases, even drop below 180V.

[0003] Excessively low supply voltage can lead to decreased efficiency of some electrical equipment, even affecting its lifespan, and also increase distribution costs, adversely impacting the economic operation of the system. This vicious cycle of inefficient equipment operation, soaring line losses, and rising maintenance costs not only reduces the user's electricity experience but also hinders the rural electrification process and the overall economic efficiency of the distribution network.

[0004] Currently, the frequent low-voltage problems at the end of the power grid are identified and prevented through user complaints and periodic inspections. This passive approach is inefficient and cannot resolve issues in a timely manner, severely impacting the performance of regional power transmission and distribution equipment. Summary of the Invention

[0005] This invention proposes a low-voltage distribution area detection device that can identify various typical operating data characteristics that lead to misjudgments, thereby reducing false alarms, improving monitoring accuracy, reducing manual measurement costs and operational risks, and improving the efficiency of handling low-voltage problems.

[0006] The present invention adopts the following technical solution.

[0007] A low-voltage distribution area detection device includes two sets of detection units for different detection positions. Each detection unit includes three grounding rods. Each grounding rod contacts the cable core of a different phase cable in the detection area through cable piercing. The piercing grounding rods are specially designed, and the piercing structure enables real-time voltage transmission. They also have insulation, outdoor use, and rust prevention functions. One of the three grounding rods is the main grounding rod with a signal processing unit mounted on it. The signal processing unit of the main grounding rod is connected to the other two grounding rods via conductors. During detection, the piercing structure of the grounding rod directly contacts the cable core and transmits the three-phase voltage signal of the line to the signal processing unit in real time through the conductors. The signal processing unit is used to receive and process the voltage signal transmitted by the grounding rod piercing structure; When conducting transformer area testing, two sets of testing units are deployed at both ends of the suspected low-voltage transformer area. They simultaneously collect, upload, and compare the voltage of the lines at both ends of the suspected low-voltage transformer area to determine whether it is a low-voltage transformer area.

[0008] The power supply module has a built-in battery. When the transformer area is tested by cable puncture, the detection unit draws power directly from the three-phase line to charge the battery, so that the detection unit can maintain a power supply state to maintain the detection operation.

[0009] After the transformer area is inspected, the piercing structure of the grounding rod is removed from the cable line, and then the cable sheath is repaired using airless spraying equipment to restore the insulation properties of the cable line. The cable is one in which there is a stress relationship between the cable sheath and the insulation layer, and the stress can automatically repair the puncture site; The airless spraying equipment includes a high-pressure pump, an air supply pipe, and a spray gun. When repairing cable sheaths, the high-pressure pump pressurizes the coating to 10-25 MPa, atomizes it through a special nozzle, and sprays it directly onto the cable surface, forming a uniform insulation layer in one pass without the need for compressed air. Before spraying, the cable is pre-treated by cleaning the cable sheath surface and removing impurities. After spraying, a uniform insulation layer can be formed on the cable surface in one pass, and the spraying speed is fast and efficient.

[0010] Grounding rod structure for cable piercing, such as Figure 2 As shown, its main structure includes a handle inserted into the grounding rod body. The upper part of the handle has a bent metal operating head. Within the bending range of the operating head, the top of the handle has a metal piercing element for cable piercing. The upper part of the operating head is a hook, and the lower part has a large nut connected to the threaded structure on the upper part of the handle. When piercing the cable, the hook is first placed on the cable to secure the piercing rod. Then, the handle is rotated, and the engagement between the handle's threaded structure and the large nut on the operating head raises the handle, allowing the piercing element at the top of the handle to penetrate the cable. When piercing is complete, the handle is rotated in the opposite direction to lower it, detaching the piercing element from the cable. This structure allows the grounding rod to be installed on transmission lines for extended periods to meet monitoring requirements, while also facilitating disassembly. Rust prevention and conductivity requirements are also considered.

[0011] The handle is a screw, and the operating head, screw, and nut are all made of pure copper and have been tin-plated on the surface. The piercing elements are arranged in two rows on the top of the handle. They are made of pure copper, with four piercing elements in each row. They are processed to be sharp and tough to ensure better contact and conductivity, and the surface is not tin-plated.

[0012] The lower part of the operating head is equipped with a small metal nut that connects to the wire, which is used to transmit the voltage of the transmission line to the signal processing unit at the grounding rod in real time.

[0013] To meet insulation requirements, the grounding rod is made of epoxy resin, which is ultra-lightweight and high-voltage resistant, meeting the needs of long-term line voltage monitoring. The length and diameter of the rod are adjusted according to the voltage level; an insulating silicone sleeve is installed on the handle for insulation and easy gripping.

[0014] During testing, one of the three grounding rods is selected as the main grounding rod, and a signal processing unit for receiving and processing the voltage signal transmitted by the grounding rod is installed on the upper part of the main grounding rod. The signal processing unit mainly includes a signal transmission module, a communication module, and a power supply module; The signal transmission module contains three current transformers with a voltage measurement error of less than 1V, enabling real-time voltage monitoring within the range of 10 to 260V. The current transformers convert the three-phase voltage into a low-voltage signal and calculate the magnitude and phase of the three-phase voltage in real time. The communication module is responsible for transmitting the calculated three-phase voltage signal to the designated server. It also has a built-in high-precision time synchronization system, which enables the two sets of detection units to synchronize data and ensure the accuracy of low voltage judgment. The power supply module includes a battery, a voltage detection module, and a switch. When the grounding rod is hung on the transmission line and penetrates the cable core, the power supply module converts the line voltage into DC power to charge the battery. Therefore, the proposed method can realize long-term monitoring of the transmission line voltage.

[0015] The voltage detection module is used to display the device's power level; The switch is used to control the working status of the detection device.

[0016] When conducting low-voltage distribution area detection in the distribution network, the detection device continuously samples the cables within a period of time in the low-voltage overhead line and household meter line area, and sends the collected voltage value, voltage information and time information of the collection point to a remote server. The server analyzes the received measurement data through algorithms to determine whether there is low voltage at that location. The algorithm used in the analysis is as follows: compare the voltage signals of each phase of the two detection units in real time. When the voltage difference is greater than 10%, it is determined that there is a low-voltage area in the cable area between the two detection units. Typical application scenarios for the low-voltage distribution area detection device are shown in the attached figure. Figure 2 As shown, D~K are the access points of the low-voltage distribution area detection device, and the area between the lines is the detection area to be determined as a possible low-voltage weak point; The specific implementation process includes the following methods: Method 1) Install two detection units at adjacent detection points (such as D and E, F and G, etc.) to monitor whether there are low voltage weak points between the lines; Method 2 involves installing the detection unit at a remote detection point (such as I and K, F and H, etc.) to determine whether there are low-voltage weak points in the area, thereby further narrowing down the low-voltage area. The low-voltage detection device includes a microcontroller, which uploads the collected voltage signal to the cloud platform and uses comparison logic to determine the low-voltage weak point. Although the proposed detection device can collect and compare the line voltage at both ends of a certain transformer area in real time, if the load of the transformer area is small, resulting in a small voltage difference between the two ends of the line, it is impossible to determine whether it is a low-voltage weak point. Therefore, a time-domain-based discrimination method is used for detection. Specifically, the peak load period of the transformer area to be detected is determined by the power distribution network power consumption acquisition system, and then the voltage difference between the two ends of the transformer area is compared with the voltage signal collected by the cloud platform to determine whether it is a low-voltage weak point.

[0017] After the grounding rod pierces the inner core of the contact cable, the three-phase voltage of the cable core is first connected to the hardware circuit of the signal processing unit. Each phase voltage is shunt using four 110kΩ resistors (1206 packaged resistors for heat dissipation). The input signal is converted into a small current signal by a ZMPT107-5 current-type voltage transformer, then into a small voltage signal by a 110Ω resistor, and finally amplified by a tail differential circuit and an RC filter circuit. The tail differential circuit receives a 1.625V DC bias because the microcontroller can only sample voltage signals between 0-3.5V. Therefore, the tail differential circuit of each phase ultimately outputs a reduced power frequency bias of 1.625V, which is then sent to the microcontroller for sampling and calculation. Attached Figure Description

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Appendix Figure 1 This is a schematic diagram illustrating the detection of low-voltage distribution areas in an embodiment of the present invention; Appendix Figure 2 This is a schematic diagram of a grounding rod piercing a cable in an embodiment of the present invention; Appendix Figure 3 This is a schematic diagram of a typical application scenario of the low-voltage distribution area detection device in an embodiment of the present invention; Appendix Figure 4 This is a schematic diagram of the hardware circuit topology of the grounding rod in an embodiment of the present invention; In the diagram: 1-Grounding rod; 2-Signal processing unit; 3-Piercing part; 4-Threaded structure; 5-Small nut; 6-Wire; 7-Handle; 8-Grounding rod body; 9-Large nut; 10-Operating head; 11-Cable. Detailed Implementation

[0020] As shown in the figure, a low-voltage distribution area detection device includes two sets of detection units for different detection positions. Each detection unit includes three grounding rods 1. Each grounding rod contacts the cable core of a different phase cable 11 in the detection area through cable piercing. The piercing grounding rods are specially designed, and the piercing structure enables real-time voltage transmission. They also have functions such as insulation, outdoor use, and rust prevention. One of the three grounding rods is the main grounding rod with a signal processing unit 2 installed on top. The signal processing unit of the main grounding rod is connected to the other two grounding rods via conductors. During detection, the piercing structure of the grounding rod directly contacts the cable core and transmits the three-phase voltage signal of the line to the signal processing unit in real time through the conductors. The signal processing unit is used to receive and process the voltage signal transmitted by the grounding rod piercing structure; When conducting transformer area testing, two sets of testing units are deployed at both ends of the suspected low-voltage transformer area. They simultaneously collect, upload, and compare the voltage of the lines at both ends of the suspected low-voltage transformer area to determine whether it is a low-voltage transformer area.

[0021] The power supply module has a built-in battery. When the transformer area is tested by cable puncture, the detection unit draws power directly from the three-phase line to charge the battery, so that the detection unit can maintain a power supply state to maintain the detection operation.

[0022] After the transformer area is inspected, the piercing structure of the grounding rod is removed from the cable line, and then the cable sheath is repaired using airless spraying equipment to restore the insulation properties of the cable line. The cable is one in which there is a stress relationship between the cable sheath and the insulation layer, and the stress can automatically repair the puncture site. The airless spraying equipment includes a high-pressure pump, an air supply pipe, and a spray gun. When repairing cable sheaths, the high-pressure pump pressurizes the coating to 10-25 MPa, atomizes it through a special nozzle, and sprays it directly onto the cable surface, forming a uniform insulation layer in one pass without the need for compressed air. Before spraying, the cable is pre-treated by cleaning the cable sheath surface and removing impurities. After spraying, a uniform insulation layer can be formed on the cable surface in one pass, and the spraying speed is fast and efficient.

[0023] Grounding rod structure for cable piercing, such as Figure 2As shown, its main structure includes a handle 7 inserted inside the grounding rod body 8. The upper part of the handle has a bent metal operating head. Within the bending range of the operating head 10, the top of the handle has a metal piercing element for cable piercing. The upper part of the operating head is a hook, and the lower part has a large nut 9 connected to the threaded structure 4 on the upper part of the handle. When piercing the cable, the hook is first placed on the cable to fix the piercing rod. Then, the handle is rotated, and the engagement between the handle's threaded structure and the large nut on the operating head raises the handle, allowing the piercing element 3 at the top of the handle to pierce the cable. When piercing is complete, the handle is rotated in the opposite direction to lower it, causing the piercing element at the top of the handle to detach from the cable. This structure allows the grounding rod to be installed on the transmission line for a long time to meet monitoring requirements, while also facilitating disassembly. Rust prevention and conductivity requirements are also considered.

[0024] The handle is a screw, and the operating head, screw, and nut are all made of pure copper and have been tin-plated on the surface. The piercing elements are arranged in two rows on the top of the handle. They are made of pure copper, with four piercing elements in each row. They are processed to be sharp and tough to ensure better contact and conductivity, and the surface is not tin-plated.

[0025] The lower part of the operating head is equipped with a small metal nut 5 connected to the wire 6, which is used to transmit the voltage of the transmission line to the signal processing unit at the grounding rod in real time.

[0026] To meet insulation requirements, the grounding rod is made of epoxy resin, which is ultra-lightweight and high-voltage resistant, meeting the needs of long-term line voltage monitoring. The length and diameter of the rod are adjusted according to the voltage level; an insulating silicone sleeve is installed on the handle for insulation and easy gripping.

[0027] During testing, one of the three grounding rods is selected as the main grounding rod, and a signal processing unit for receiving and processing the voltage signal transmitted by the grounding rod is installed on the upper part of the main grounding rod. The signal processing unit mainly includes a signal transmission module, a communication module, and a power supply module; The signal transmission module contains three current transformers with a voltage measurement error of less than 1V, enabling real-time voltage monitoring within the range of 10 to 260V. The current transformers convert the three-phase voltage into a low-voltage signal and calculate the magnitude and phase of the three-phase voltage in real time. The communication module is responsible for transmitting the calculated three-phase voltage signal to the designated server. It also has a built-in high-precision time synchronization system, which enables the two sets of detection units to synchronize data and ensure the accuracy of low voltage judgment. The power supply module includes a battery, a voltage detection module, and a switch. When the grounding rod is hung on the transmission line and penetrates the cable core, the power supply module converts the line voltage into DC power to charge the battery. Therefore, the proposed method can realize long-term monitoring of the transmission line voltage.

[0028] The voltage detection module is used to display the device's power level; The switch is used to control the working status of the detection device.

[0029] When conducting low-voltage distribution area detection in the distribution network, the detection device continuously samples the cables within a period of time in the low-voltage overhead line and household meter line area, and sends the collected voltage value, voltage information and time information of the collection point to a remote server. The server analyzes the received measurement data through algorithms to determine whether there is low voltage at that location. The algorithm used in the analysis is as follows: compare the voltage signals of each phase of the two detection units in real time. When the voltage difference is greater than 10%, it is determined that there is a low-voltage area in the cable area between the two detection units. Typical application scenarios for the low-voltage distribution area detection device are shown in the attached figure. Figure 2 As shown, D~K are the access points of the low-voltage distribution area detection device, and the area between the lines is the detection area to be determined as a possible low-voltage weak point; The specific implementation process includes the following methods: Method 1) Install two detection units at adjacent detection points (such as D and E, F and G, etc.) to monitor whether there are low voltage weak points between the lines; Method 2 involves installing the detection unit at a remote detection point (such as I and K, F and H, etc.) to determine whether there are low-voltage weak points in the area, thereby further narrowing down the low-voltage area. The low-voltage detection device includes a microcontroller, which uploads the collected voltage signal to the cloud platform and uses comparison logic to determine the low-voltage weak point. Although the proposed detection device can collect and compare the line voltage at both ends of a certain transformer area in real time, if the load of the transformer area is small, resulting in a small voltage difference between the two ends of the line, it is impossible to determine whether it is a low-voltage weak point. Therefore, a time-domain-based discrimination method is used for detection. Specifically, the peak load period of the transformer area to be detected is determined by the power distribution network power consumption acquisition system, and then the voltage difference between the two ends of the transformer area is compared with the voltage signal collected by the cloud platform to determine whether it is a low-voltage weak point.

[0030] After the grounding rod pierces the inner core of the contact cable, the three-phase voltage of the cable core is first connected to the hardware circuit of the signal processing unit. Each phase voltage is shunt using four 110kΩ resistors (1206 packaged resistors for heat dissipation). The input signal is converted into a small current signal by a ZMPT107-5 current-type voltage transformer, then into a small voltage signal by a 110Ω resistor, and finally amplified by a tail differential circuit and an RC filter circuit. The tail differential circuit receives a 1.625V DC bias because the microcontroller can only sample voltage signals between 0-3.5V. Therefore, the tail differential circuit of each phase ultimately outputs a reduced power frequency bias of 1.625V, which is then sent to the microcontroller for sampling and calculation.

[0031] Example: This example is attached Figure 1 As shown. The technical solution adopted is as follows: The device consists of two identical detection units. The main body of each detection unit includes three piercing grounding rods, which are connected to the three-phase lines respectively. The piercing structure of the grounding rods can directly contact the cable core and transmit the three-phase voltage signals of the line to the signal processing unit in real time through the conductors.

[0032] The piercing grounding rod needs to have the following functions: (1) insulation and safety; (2) the piercing needle can pass through the cable / overhead line; (3) outdoor use; (4) rust prevention. Therefore, the proposed structure of the piercing grounding rod is as follows: Figure 2 As shown, its main structure includes: an operating head, a piercing rod, a screw, a large nut, a small nut, a rod body, and a handle. The operating head and the large nut are fixed as a single unit. By rotating the large nut, the distance between the operating head and the piercing rod can be adjusted. The transmission line is placed between the operating head and the piercing rod. By adjusting the distance, the connection and disconnection between the piercing rod and the transmission line can be achieved, that is, the grounding rod can be installed on the transmission line or removed from the transmission line. This structure can meet the monitoring requirements for long-term installation of the grounding rod on the transmission line, while also facilitating disassembly. Considering the requirements for rust prevention and conductivity, the operating head, screw, and nut are all made of pure copper and tin-plated. The piercing rod is made of pure copper, processed to be sharp and tough, providing better contact conductivity, and its surface is not tin-plated. The small nut connects to the conductor, transmitting the voltage of the transmission line to the signal processing unit in real time. To meet insulation requirements, the rod body is made of epoxy resin, which is ultra-lightweight and high-voltage resistant, meeting the requirements for long-term monitoring of line voltage. The length and diameter of the rod body are adjusted according to the voltage level. An insulating silicone sleeve is installed on the handle for insulation and easy gripping.

[0033] Furthermore, the puncture must be sharp and tough enough to easily penetrate the cable insulation layer and form good contact with the conductor; simultaneously, the removal of the puncture should not affect the cable's continued operation. Therefore, the puncture size can be adjusted according to the actual cable size. Taking a 240mm² copper cable conductor (current carrying capacity 1000A) as an example, the cable sheath thickness is between 1-3mm, so the puncture length is 5mm. To avoid damaging the thick sheath while ensuring penetration of the insulation layer, the puncture tip diameter is 1mm and the bottom diameter is 2mm, forming a conical shape to facilitate insulation penetration while maintaining good mechanical strength. After the puncture is removed, the cable sheath and insulation layer will automatically repair themselves due to stress; to further improve safety and insulation, insulating spraying can be applied to the puncture site. The above operations comply with power grid operation and maintenance specifications at the 400V voltage level. The insulation spraying method employs airless spraying. The basic structure includes a high-pressure pump, air supply pipe, and spray gun. The high-pressure pump pressurizes the coating to 10-25 MPa, atomizes it through a special nozzle, and sprays it directly onto the cable surface without the need for compressed air. Before spraying, the cable is pre-treated by cleaning the cable sheath surface and removing impurities. After spraying, a uniform insulation layer is formed on the cable surface in one pass, and the spraying speed is fast and efficient. Furthermore, the piercings on a grounding rod are arranged in two rows, with four piercings in each row.

[0034] One of the three grounding rods is selected as the main grounding rod, and a signal processing unit is installed on top of it to receive and process the voltage signal transmitted by the grounding rod. The signal processing unit mainly includes a signal transmission module, a communication module, and a power supply module. The signal transmission module contains three current transformers with a voltage measurement error of less than 1V, enabling real-time voltage monitoring within the range of 10 to 260V. The current transformers convert the three-phase voltage into low-voltage signals and calculate the magnitude and phase of the three-phase voltage in real time. The communication module is responsible for transmitting the calculated three-phase voltage signals to a designated server and also has a built-in high-precision time synchronization system, enabling data synchronization between the two detection units and ensuring the accuracy of low-voltage judgment. The power supply module includes a battery, a voltage detection module, and a switch. When the grounding rod is attached to the transmission line, the line voltage is converted into DC current to charge the battery; therefore, the proposed method can achieve long-term monitoring of the transmission line voltage. The voltage detection module displays the device's power level. The switch controls the operating status of the detection device.

[0035] The monitoring device continuously samples the low-voltage overhead lines and household meter lines during their cycles, sending the collected voltage values, voltage information, and time information of the sampling points to the server. The server then uses software algorithms to determine whether low voltage exists at the location based on the received measurement data. Specifically, the algorithm compares the voltage signals of each phase of the two detection units in real time; if the voltage difference is greater than 10%, a low-voltage area is identified.

[0036] Typical application scenarios of the low-voltage zone detection device of the present invention are shown in the appendix. Figure 2 As shown, D~K are the access points of the low-voltage distribution area detection device, and the lines between them represent potential low-voltage weak points. Specific implementation schemes include: 1) Installing detection units at adjacent detection points (e.g., D and E, F and G, etc.) to monitor whether there are low-voltage weak points between the lines; 2) Installing detection units at distant detection points (e.g., I and K, F and H, etc.) to determine whether there are low-voltage weak points in the area, thereby further narrowing down the low-voltage distribution area. The microcontroller of the low-voltage detection device uploads the collected voltage signals to the cloud platform, and determines the low-voltage weak points through comparison logic. Although the proposed detection device can collect and compare the line voltages at both ends of a distribution area in real time, if the load of the distribution area is relatively small, the voltage difference between the two ends of the line is also small, making it impossible to determine whether it is a low-voltage weak point. Therefore, a time-domain-based discrimination method is proposed. Specifically, the peak load period of the distribution area to be detected is determined through the power distribution network consumption acquisition system, and then the voltage difference between the two ends of the distribution area is compared with the voltage signals collected by the cloud platform to determine whether it is a low-voltage weak point.

[0037] The hardware circuit topology for this example is shown in the attached figure. Figure 4 As shown, the three-phase voltage is first connected to the hardware circuit. Each phase is shunt using four 110kΩ resistors in a 1206 package for heat dissipation. The input signal is converted into a small current signal by a ZMPT107-5 current-type voltage transformer, then into a small voltage signal by the 110Ω resistors, and finally amplified by a differential circuit and an RC filter circuit. The differential circuit receives a 1.625V DC bias because the microcontroller can only sample voltage signals between 0-3.5V. Therefore, the differential circuit of each phase ultimately outputs a reduced power frequency bias of 1.625V, which is then fed into the microcontroller for sampling and calculation.

Claims

1. A power distribution network low-voltage transformer area detection device, characterized in that: The detection unit includes two sets of detection units for different detection positions, each set of detection unit includes three grounding rods, each grounding rod is connected with the cable core of different phase cable through cable piercing, one of the three grounding rods is the main grounding rod which is installed with signal processing unit, the signal processing unit of the main grounding rod is connected with the other two grounding rods through wires, during detection, the piercing structure of the grounding rod directly contacts the cable core and transmits the three-phase voltage signal of the line to the signal processing unit in real time; The signal processing unit is used for receiving and processing the voltage signal transmitted by the piercing structure of the grounding rod; When detecting the transformer area, two sets of detection units are arranged at both ends of the suspected low-voltage transformer area, and the voltage data of the line at both ends of the suspected low-voltage transformer area is collected, uploaded and compared to determine whether it is a low-voltage transformer area.

2. The power distribution network low-voltage transformer area detection device according to claim 1, characterized in that: The power supply module is provided with a built-in battery, when detecting the transformer area through cable piercing, the detection unit directly takes power from the three-phase line to charge the battery, so that the detection unit maintains the power supply state to maintain the detection condition.

3. The power distribution network low-voltage transformer area detection device of claim 1, wherein: After detecting the transformer area, the piercing structure of the grounding rod is taken out from the cable line, and then the cable surface is repaired using a gasless spraying device to restore the insulation properties of the cable line. The cable is a cable with a stress relationship between the cable sheath and the insulation layer and a stress automatic repair piercing position. The gasless spraying device includes a high-pressure pump, a gas delivery pipe and a spray gun, when repairing the cable surface, the coating is pressurized to 10-25MPa by the high-pressure pump, and is directly sprayed to the cable surface after being atomized by a special nozzle to form a uniform insulation layer on the cable surface.

4. The power distribution network low-voltage transformer area detection device of claim 1, wherein: The grounding rod structure for cable piercing includes a handle arranged in the grounding rod shaft, the upper part of the handle is provided with a bent metal operating head, the top end of the handle in the bending range of the operating head is provided with a metal piercing element for cable piercing, the upper part of the operating head is a hook part, and the lower part of the operating head is provided with a large nut connected with the threaded structure of the upper part of the handle, when performing cable piercing, the hook part is first hung at the cable to fix the piercing rod, then the handle is rotated, the handle is lifted by the cooperation of the threaded structure of the handle and the large nut of the operating head, and the piercing element at the top end of the handle is pierced into the cable, when the piercing is completed, the handle is rotated in the opposite direction to lower the handle, and the piercing element at the top end of the handle is separated from the cable.

5. The power distribution network low-voltage transformer area detection device according to claim 4, characterized in that: The handle is a screw rod, the operating head, the screw rod and the nut are all made of pure copper and are tin-plated on the surface. The piercing element is arranged in two rows on the top of the handle and is made of pure copper without tin plating on the surface.

6. The power distribution network low-voltage transformer area detection device of claim 4, wherein: The lower part of the operating head is provided with a small metal nut connected with the wire for transmitting the voltage of the power transmission line to the signal processing unit at the grounding rod shaft.

7. The power distribution network low-voltage transformer area detection device of claim 6, wherein: The grounding rod shaft is made of epoxy resin material, and the length and diameter of the shaft are adjusted according to the voltage grade; an insulating silica gel sleeve is installed outside the handle.

8. The power distribution network low-voltage transformer area detection device of claim 4, wherein: During detection, one of the three grounding rods is selected as the main grounding rod, and a signal processing unit for receiving and processing the voltage signal transmitted by the grounding rod is installed on the upper part of the main grounding rod; The signal processing unit mainly includes a signal transmission module, a communication module and a power supply module; The signal transmission module includes three transformers, which convert three-phase voltage into low-voltage signal and calculate the size and phase of three-phase voltage in real time. The communication module is responsible for transmitting the calculated three-phase voltage signal to the designated server, while the built-in high-precision timing system ensures that the two detection units are synchronized, ensuring the accuracy of low voltage determination. The power supply module includes a battery, a voltage detection module, and a switch. When the grounding rod is hung on the power transmission line and pierced into the cable core, the power supply module converts the line voltage into direct current to charge the battery. The voltage detection module is used to display the power of the grounding rod device.

9. The power distribution network low-voltage transformer area detection device of claim 4, wherein: When detecting the low-voltage area of the power distribution network, the detection device continuously samples the cable in the low-voltage overhead line and household meter line area, and sends the collected voltage value, voltage information, and time information of the measurement point to the remote server. The server analyzes the received measurement data through an algorithm to determine whether there is low voltage at that location. The algorithm used for analysis is as follows: real-time comparison of voltage signals of two detection units per phase, when the voltage difference is greater than 10% or more, it is determined that there is a low voltage area between the two detection units. When the low-voltage area detection device is in use, D~K is the access point of the low-voltage area detection device, and the line is the detection area where there may be a low-voltage weak point. The specific implementation process includes the following methods: Method 1) Install two detection units at adjacent detection points to monitor whether the line is a low-voltage weak point. Method 2) Install the detection unit at a remote detection point to determine whether there is a low-voltage weak point in the area, thereby further narrowing the scope of the low-voltage area. The low-voltage detection device includes a single-chip microcomputer for uploading the collected voltage signal to the cloud platform and determining the low-voltage weak point through comparison logic. If the load of the area is small, making the voltage difference between the two ends of the line small, and unable to determine whether it is a low-voltage weak point, the detection is carried out through a time-domain-based discrimination method, which is: determining the peak load period of the detection area through the power distribution network power collection system, and comparing the voltage difference between the two ends of the area based on the voltage signal collected by the cloud platform, to determine whether it is a low-voltage weak point.

10. The power distribution network low-voltage transformer area detection device of claim 9, wherein: After the grounding rod pierces the cable core, the three-phase voltage signal of the cable core is first connected to the hardware circuit of the signal processing unit. Each phase voltage is divided by four resistors, the input signal is converted into a small current signal by a current-type voltage transformer, and then the signal is amplified by a tail differential circuit and an RC filter circuit, and the output is a small power frequency signal. The signal is then sent to the single-chip microcomputer for sampling and calculation.

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