A fault detection method for multi-user low-voltage power supply lines

Abstract

The present invention discloses a fault detection method for multi-user low-voltage power supply lines. By using a multi-functional power line detector, the probes located on the host and the terminal acquisition unit of the multi-functional power line detector are respectively connected to the power distribution network, and the circuit data of any low-voltage power supply line in the power distribution network can be obtained simultaneously. Based on all the circuit data, the host can quickly analyze and judge the fault type and fault location. Compared with the traditional manual inspection, the present invention provides a comprehensive solution for line inspection, repair and fault detection of the power distribution network in complex environments. It can not only detect faults of a single line simultaneously, but also detect faults of a power distribution network composed of several low-voltage power supply lines, effectively solving the problem that it is difficult to quickly determine the fault location and fault type in the current power distribution network inspection method, and achieving the effects of improving the inspection efficiency and inspection accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of power supply line fault diagnosis, and particularly relates to a fault detection method for multi-user low-voltage power supply lines. Background Art

[0002] At present, the functions and structures of distribution networks are relatively single, the fault management and autonomous capabilities of distribution networks are weak, and the new energy acceptance capabilities are low. In terms of infrastructure construction, compared with transmission networks, problems such as aging distribution equipment and fault power outages are more prominent. Therefore, in order to improve the reliability of power supply in distribution networks and meet the strategic goals such as the energy Internet, new industrialization, and urbanization construction, the construction and transformation of distribution networks are being vigorously promoted.

[0003] To ensure the stable operation of the distribution network, it is necessary to regularly inspect the distribution network, that is, to check each suspicious low-voltage power supply line in the faulty distribution network one by one through workers, so as to determine the fault location. Although the current inspection method can meet the inspection requirements of traditional distribution networks, under the construction and transformation of distribution networks, the coverage of distribution networks changes greatly, and the connected equipment is more complex, making faults not only occur at a single location, but also easily lead to a chain fault reaction in the entire distribution network, resulting in difficult inspection. When workers conduct inspections, they need to carry multiple devices to collect circuit data of multiple suspicious low-voltage power supply lines at the same time, and then analyze and judge based on all circuit data. This process not only consumes a lot of manpower, material resources, and time, but also is difficult to quickly determine the fault location and fault type. Summary of the Invention

[0004] Aiming at the above deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a fault detection method for multi-user low-voltage power supply lines, solve the problem that it is difficult to quickly determine the fault location and fault type in the current distribution network inspection method, and achieve the effects of improving the inspection efficiency and inspection accuracy.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A fault detection method for multi-user low-voltage power supply lines, the fault detection method uses a multi-functional electrical circuit detector. The multi-functional electrical circuit detector includes a main unit, an end acquisition unit, and a plurality of detection units. Each detection unit includes two probes respectively electrically connected to the main unit and the end acquisition unit, and the main unit and the end acquisition unit are communicatively connected; the fault detection method includes the following steps:

[0007] 1) Based on the main unit time, perform clock synchronization calibration on the main unit and the end acquisition unit;

[0008] 2) Arrange the several detection units in a distribution network including several low-voltage power supply lines, and connect the two probes of the same detection unit to one low-voltage power supply line;

[0009] 3) Each detection unit collects the circuit data of the corresponding connected low-voltage power supply line;

[0010] 4) The host obtains the circuit data of the low-voltage power supply line and performs clock synchronization calibration on the circuit data;

[0011] 5) The host analyzes and judges the circuit data after clock synchronization calibration to obtain the fault detection result.

[0012] Further, in step 3), the circuit data includes residual current data, current waveform data, and voltage waveform data.

[0013] Further, in step 2), three detection units are connected to each low-voltage power supply line, and the three detection units respectively adopt the following three connection methods:

[0014] The two probes of the same detection unit are respectively located at the head end and the tail end of the low-voltage power supply line, and the corresponding two probes are both connected between the live wire and the neutral wire, and are used to collect the residual current data of the corresponding low-voltage power supply line;

[0015] The two probes of the same detection unit are respectively located at the head end and the tail end of the low-voltage power supply line, and the corresponding two probes are both connected to the live wire or the neutral wire, and are used to collect the current waveform data on the live wire or the neutral wire of the corresponding low-voltage power supply line;

[0016] The two probes of the same detection unit are respectively located at the head end and the tail end of the low-voltage power supply line, and the corresponding two probes are respectively connected to the live wire and the neutral wire, and are used to collect the voltage waveform data between the live wire and the neutral wire of the corresponding low-voltage power supply line.

[0017] Further, in step 4), define the last 0 value in all current waveform data as I1, define the preset fault threshold as I 差 , define the first value in all current waveform data that satisfies the conditional formula |I1 - I2| ≥ |I 差 | as I2, and perform clock synchronization calibration on the circuit data based on the time point corresponding to I2.

[0018] Further, in step 5), for the voltage waveform data of the low-voltage power supply line, define the effective value of the voltage of the live wire to the neutral wire as U LN , define the effective value of the voltage of the live wire to the ground wire as U LD , define the effective value of the voltage of the neutral wire to the ground wire as U ND , define the standard effective value of the voltage of the live wire to the neutral wire as U LNSET, define the effective value of the standard voltage of the live wire to the ground wire as U LDSET , define the effective value of the standard voltage of the neutral wire to the ground wire as U NDSET ;

[0019] Make the following judgment: If |U LNSET | >> |U LN |, |U LDSET | >> |U LD | and |U NDSET | ≈ |U ND |, then it is judged that there is a break in the live wire; if |U LNSET | >> |U LN |, |U LDSET | ≈ |U LD | and |U NDSET | < |U ND |, then it is judged that there is a break in the neutral wire; if |U LNSET | ≈ |U LN |, |U LDSET | >> |U LD | and |U NDSET | << |U ND |, then it is judged that there is a break in the ground wire.

[0020] Furthermore, in step 5), for the current waveform data of the low-voltage power supply line, define the effective values of the currents collected by the two probes of the same detection unit at the head and end of the live wire as I L1 and I L2 , define the effective values of the currents collected by the two probes of the same detection unit at the head and end of the neutral wire as I N1 and I N2 ;

[0021] Make the following judgment: If |I L1 | > 0 and |I L2 | ≈ 0, then it is judged that there is a break in the live wire; if |I N1 | > 0 and |I N2 | ≈ 0, then it is judged that there is a break in the neutral wire.

[0022] Furthermore, in step 5), for the current waveform data of the low-voltage power supply line, define the instantaneous current amplitudes of any k consecutive sampling points collected by the two probes of the same detection unit at the head and end of the live wire as and Define the instantaneous current amplitudes of any k consecutive sampling points collected by the two probes of the same detection unit at the head and end of the neutral wire as and T is the time interval of each sampling point;

[0023] Make the following judgment: If If it holds, it is determined that there is a short circuit on the live wire; if holds, it is determined that there is a short circuit on the neutral wire.

[0024] Furthermore, in step 5), for the current waveform data of the low-voltage power supply line, the effective values of the Gth harmonic contents collected by the two probes of the same detection unit at the head and end of the live wire are defined as I L1-G and I L2-G , and the effective values of the Gth harmonic contents collected by the two probes of the same detection unit at the head and end of the neutral wire are defined as I N1-G and I N2-G , and the maximum effective value of the Gth harmonic content under normal conditions is defined as G SET ;

[0025] Make the following judgment: If holds, it is determined that there is an arc on the live wire; if holds, it is determined that there is an arc on the neutral wire.

[0026] Furthermore, in step 5), for the residual current data of the low-voltage power supply line, in the same detection unit, the residual current collected by one probe is I leak1 and the voltage to ground of the neutral wire at the probe connection is U ND1 , the residual current collected by the other probe is I leak2 and the voltage to ground of the neutral wire at the probe connection is U ND2 , the defined difference limit value of the residual current is I leak-set , and the difference limit value of the voltage to ground of the neutral wire is U leak-set ;

[0027] Make the following judgment: If holds, it is determined that there is a leakage on the corresponding low-voltage power supply line.

[0028] Furthermore, the communication connection between the host and the end collection unit adopts LoRa wireless communication technology.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The fault detection method for multi-user low-voltage power supply lines of the present invention uses a multi-functional power line detector. The probes located on the host and the terminal acquisition unit of the multi-functional power line detector are respectively connected to the distribution network, and the circuit data of any low-voltage power supply line in the distribution network can be obtained simultaneously. Based on all the circuit data, the host can quickly analyze and judge the fault type and fault location. Compared with the traditional manual inspection, the present invention proposes a comprehensive solution that can handle the line inspection, repair, and fault detection of the distribution network in a complex environment. It can not only detect faults in a single line simultaneously but also detect faults in a distribution network composed of several low-voltage power supply lines, effectively solving the problem that it is difficult to quickly determine the fault location and fault type in the current distribution network inspection method, and achieving the effects of improving the inspection efficiency and inspection accuracy.

[0031] 2. The fault detection method for multi-user low-voltage power supply lines of the present invention not only performs clock synchronization calibration on the host and the terminal acquisition unit before the detection starts but also performs clock synchronization calibration on all the circuit data after the circuit data acquisition is completed, which can effectively improve the accuracy of the fault detection results.

[0032] 3. The fault detection method for multi-user low-voltage power supply lines of the present invention uses the current waveform data, voltage waveform data, and residual current data respectively to analyze and judge the fault type and fault location, which is convenient for maintenance personnel to quickly formulate a maintenance and rectification plan according to the fault type and fault location, and is beneficial to improving the efficiency of the distribution network maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flowchart of a fault detection method for multi-user low-voltage power supply lines according to an embodiment;

[0034] Figure 2 It is a schematic diagram of the connection mode of two probes in the detection unit and the line according to the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present invention provided herein is not intended to limit the scope of the claimed invention but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0036] It should be noted that like reference numerals and letters refer to like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance. In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging vertically, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Embodiment:

[0038] Please refer to Figure 1 , a fault detection method for a multi-user low-voltage power supply line. The fault detection method uses a multi-functional detector for an electric power line. The multi-functional detector for an electric power line includes a host, an end acquisition unit, and a plurality of detection units. Each detection unit includes two probes respectively electrically connected to the host and the end acquisition unit, and the host and the end acquisition unit are communicatively connected. In this embodiment, the communication connection between the host and the end acquisition unit adopts LoRa wireless communication technology;

[0039] The fault detection method includes the following steps:

[0040] 1) Based on the host time, perform clock synchronization calibration on the host and the end acquisition unit;

[0041] 2) Connect and arrange the plurality of detection units in a power distribution network including a plurality of low-voltage power supply lines, and connect the two probes of the same detection unit to a low-voltage power supply line;

[0042] 3) Each detection unit collects the circuit data of the corresponding low-voltage power supply line connected thereto;

[0043] 4) The host obtains the circuit data of all low-voltage power supply lines and performs clock synchronization calibration on the circuit data;

[0044] 5) The host analyzes and judges the obtained circuit data after clock synchronization calibration to obtain the fault detection result.

[0045] For the fault detection method for multi-user low-voltage power supply lines of the present invention, an electric circuit multi-functional detector is used. The probes located on the host and the terminal acquisition unit of the electric circuit multi-functional detector are respectively connected to the power distribution network, and the circuit data of any low-voltage power supply line in the power distribution network can be obtained simultaneously. Based on all the circuit data, the host can quickly analyze and judge the fault type and fault location. Compared with the traditional manual inspection, the fault detection method for multi-user low-voltage power supply lines of the present invention can not only detect the faults of a single line simultaneously, but also detect the faults of the power distribution network composed of several low-voltage power supply lines, effectively solving the problem that it is difficult to quickly determine the fault location and fault type in the current power distribution network inspection method, and achieving the effects of improving the inspection efficiency and inspection accuracy.

[0046] For the convenience of the host to analyze and judge the fault type and fault location of the line, in step 3), the circuit data to be obtained includes residual current data, current waveform data, and voltage waveform data. Correspondingly, in step 2), three detection units are connected to each low-voltage power supply line, and the three detection units respectively adopt the following three connection methods:

[0047] Two probes of the same detection unit are respectively located at the head end and the tail end of the low-voltage power supply line, and the corresponding two probes are both connected between the live wire and the neutral wire, for collecting the residual current data of the corresponding low-voltage power supply line; as Figure 2 shown in, the connection method of the probes CT0_1 and CT0_2 to the line;

[0048] Two probes of the same detection unit are respectively located at the head end and the tail end of the low-voltage power supply line, and the corresponding two probes are both connected to the live wire or the neutral wire, for collecting the current waveform data on the live wire or the neutral wire of the corresponding low-voltage power supply line; as Figure 2 shown in, the connection method of the probes CT1 and CT2 to the line;

[0049] Two probes of the same detection unit are respectively located at the head end and the tail end of the low-voltage power supply line, and the corresponding two probes are respectively connected to the live wire and the neutral wire, for collecting the voltage waveform data between the live wire and the neutral wire of the corresponding low-voltage power supply line; Figure 2 not shown in.

[0050] To improve the accuracy of the fault detection results, in the fault detection method for multi-user low-voltage power supply lines according to the present invention, not only are the host and the terminal acquisition units subjected to clock synchronization calibration before the detection starts, but also, after the circuit data acquisition is completed, all the circuit data are subjected to clock synchronization calibration; the specific operations in step 4) are as follows: Define the last 0 value in all the current waveform data as I1, define the preset fault threshold as I 差 , define the first value in all the current waveform data that satisfies the conditional formula |I1 - I2| ≥ |I 差 | as I2, and perform clock synchronization calibration on the circuit data based on the time point corresponding to I2.

[0051] To facilitate the maintenance of the line according to the fault detection results, in step 5), the current waveform data, the voltage waveform data, and the residual current data are respectively used to analyze and judge the fault type and the fault location, which specifically includes the following sub-steps, and there is no sequence among the steps:

[0052] 51) For the voltage waveform data of the low-voltage power supply line, define the effective voltage value of the live wire to the neutral wire as U LN , define the effective voltage value of the live wire to the ground wire as U LD , define the effective voltage value of the neutral wire to the ground wire as U ND , define the standard effective voltage value of the live wire to the neutral wire as U LNSET , define the standard effective voltage value of the live wire to the ground wire as U LDSET , define the standard effective voltage value of the neutral wire to the ground wire as U NDSET ;

[0053] Make the following judgments: If |U LNSET | >> |U LN |, |U LDSET | >> |U LD | and |U NDSET | ≈ |U ND |, then it is judged that there is a break in the live wire; if |U LNSET | >> |U LN |, |U LDSET | ≈ |U LD | and |U NDSET | < |U ND |, then it is judged that there is a break in the neutral wire; if |U LNSET | ≈ |U LN |, |U LDSET | >> |U LD | and |U NDSET | << |U ND |, then it is judged that there is a break in the ground wire.

[0054] 52) For the current waveform data of the low-voltage power supply line, define the effective values of the currents collected by the two probes of the same detection unit at the head and end of the live wire as I L1 and I L2 , and define the effective values of the currents collected by the two probes of the same detection unit at the head and end of the neutral wire as I N1 and I N2 ;

[0055] Make the following judgments: If |I L1 | > 0 and |I L2 | ≈ 0, then it is judged that there is a break in the live wire; if |I N1 | > 0 and |I N2 | ≈ 0, then it is judged that there is a break in the neutral wire.

[0056] 53) For the current waveform data of the low-voltage power supply line, define the instantaneous current amplitudes of any k consecutive sampling points collected by the two probes of the same detection unit at the head and end of the live wire as and Define the instantaneous current amplitudes of any k consecutive sampling points collected by the two probes of the same detection unit at the head and end of the neutral wire as and T is the time interval of each sampling point;

[0057] Make the following judgments: If holds, then it is judged that there is a short circuit in the live wire; if holds, then it is judged that there is a short circuit in the neutral wire.

[0058] 54) For the current waveform data of the low-voltage power supply line, define the effective values of the Gth harmonic contents collected by the two probes of the same detection unit at the head and end of the live wire as I L1-G and I L2-G , and define the effective values of the Gth harmonic contents collected by the two probes of the same detection unit at the head and end of the neutral wire as I N1-G and I N2-G , and define the maximum effective value of the Gth harmonic content under normal conditions as G SET ;

[0059] Make the following judgments: If holds, then it is judged that there is an arc in the live wire; if holds, then it is judged that there is an arc in the neutral wire.

[0060] 55) For the residual current data of the low-voltage power supply line, define that in the same detection unit, the residual current collected by one probe is I leak1 and the voltage to ground of the neutral wire at the probe connection is U ND1 , and the residual current collected by the other probe is Ileak2 and the zero-line voltage to ground at the probe connection is U ND2 , define the difference limit value of the residual current as I leak-set , and the difference limit value of the zero-line voltage to ground as U leak-set ;

[0061] Make the following judgment: If holds, it is determined that there is a leakage on the corresponding low-voltage power supply line.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limiting the technical solutions. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the purpose and scope of the present technical solution shall be covered by the scope of the claims of the present invention.

Claims

1. A fault detection method for multi-user low-voltage power supply lines, characterized in that: The described fault detection method uses a multi-functional detector for electrical circuits. The multi-functional detector for electrical circuits includes a main unit, an end collection unit, and several detection units. Each detection unit includes two probes respectively electrically connected to the main unit and the end collection unit, and the main unit and the end collection unit are communicatively connected. The fault detection method includes the following steps: 1) Based on the time of the main unit, perform clock synchronization calibration on the main unit and the end collection unit; 2) Arrange and connect the several detection units in a power distribution network including several low-voltage power supply lines. The two probes of the same detection unit are connected to one low-voltage power supply line; 3) Each detection unit collects the circuit data of the corresponding connected low-voltage power supply line; 4) The main unit obtains the circuit data of each low-voltage power supply line and performs clock synchronization calibration on the circuit data; 5) The main unit analyzes and judges the circuit data after clock synchronization calibration to obtain the fault detection result; In step 3), the circuit data includes residual current data, current waveform data, and voltage waveform data; In step 2), three detection units are connected to each low-voltage power supply line, and the three detection units respectively adopt the following three connection methods: The two probes of the same detection unit are respectively located at the head end and the end of the low-voltage power supply line, and the corresponding two probes are both connected between the live wire and the neutral wire, for collecting the residual current data of the corresponding low-voltage power supply line; The two probes of the same detection unit are respectively located at the head end and the end of the low-voltage power supply line, and the corresponding two probes are both connected to the live wire or the neutral wire, for collecting the current waveform data on the live wire or the neutral wire of the corresponding low-voltage power supply line; The two probes of the same detection unit are respectively located at the head end and the end of the low-voltage power supply line, and the corresponding two probes are respectively connected to the live wire and the neutral wire, for collecting the voltage waveform data between the live wire and the neutral wire of the corresponding low-voltage power supply line; In step 5), for the current waveform data of the low-voltage power supply line, define the instantaneous current amplitudes of any k consecutive sampling points collected by two probes of the same detection unit at the head end and the tail end of the live wire as and Define the instantaneous current amplitudes of any k consecutive sampling points collected by two probes of the same detection unit at the head end and the tail end of the neutral wire as and T is the time interval of each sampling point. Define the effective current values collected by two probes of the same detection unit at the head end and the tail end of the live wire as I L1 and I L2 ; Make the following judgment: If holds, it is judged that there is a short circuit on the live wire; if holds, it is judged that there is a short circuit on the neutral wire.

2. The fault detection method for a multi-user low-voltage power supply line according to claim 1, characterized in that: In step 4), define the last 0 value in all current waveform data as I1, and define the preset fault threshold as I 差 , define the first value in all current waveform data that satisfies the conditional formula |I1 - I2| ≥ |I 差 | as I2, and perform clock synchronization calibration on the circuit data based on the time point corresponding to I2.

3. The fault detection method for a multi-user low-voltage power supply line according to claim 1, characterized in that: In step 5), for the voltage waveform data of the low-voltage power supply line, define the effective voltage value of the live wire to the neutral wire as U LN , define the effective voltage value of the live wire to the ground wire as U LD , define the effective voltage value of the neutral wire to the ground wire as U ND , define the standard effective voltage value of the live wire to the neutral wire as U LNSET , define the standard effective voltage value of the live wire to the ground wire as U LDSET , define the standard effective voltage value of the neutral wire to the ground wire as U NDSET ; Make the following judgments: If |U LNSET | >> |U LN |, |U LDSET | >> |U LD | and |U NDSET | ≈ |U ND |, then it is judged that there is a break in the live wire; if |U LNSET | >> |U LN |, |U LDSET | ≈ |U LD | and |U NDSET | < |U ND |, then it is judged that there is a break in the neutral wire; if |U LNSET | ≈ |U LN |, |U LDSET | >> |U LD | and |U NDSET | << |U ND |, then it is judged that there is a break in the ground wire.

4. The fault detection method for a multi-user low-voltage power supply line according to claim 1, wherein: In step 5), for the current waveform data of the low-voltage power supply line, the effective values of the current collected by the two probes of the same detection unit at the head end and the tail end of the neutral line are defined as I N1 and I N2 ; Make the following judgment: If |I L1 | > 0 and |I L2 | ≈ 0, then it is judged that there is a break in the live wire; if |I N1 | > 0 and |I N2 | ≈ 0, then it is judged that there is a break in the neutral wire.

5. The fault detection method for a multi-user low-voltage power supply line according to claim 1, characterized in that: In step 5), for the current waveform data of the low-voltage power supply line, the effective values of the Gth harmonic content collected by the two probes of the same detection unit at the head and end of the live wire are defined as I L1-G and I L2-G , the effective values of the Gth harmonic content collected by the two probes of the same detection unit at the head and end of the neutral wire are defined as I N1-G and I N2-G , and the maximum effective value of the Gth harmonic content under normal conditions is defined as G SET ; Make the following judgment: If holds, it is judged that there is an arc on the live wire; if holds, it is judged that there is an arc on the neutral wire.

6. The fault detection method for a multi-user low-voltage power supply line according to claim 1, characterized in that: In step 5), for the residual current data of the low-voltage power supply line, in the same detection unit, the residual current collected by one probe is defined as I leak1 and the voltage to ground of the neutral line at the probe connection is U ND1 , the residual current collected by the other probe is I leak2 and the voltage to ground of the neutral line at the probe connection is U ND2 , the defined limit value of the residual current difference is I leak-set , and the defined limit value of the voltage to ground of the neutral line difference is U leak-set ; Make the following judgment: If holds, it is determined that there is a leakage on the corresponding low-voltage power supply line.

7. The fault detection method for multi - user low - voltage power supply lines according to claim 1, wherein: The communication connection between the main unit and the end collection unit adopts LoRa wireless communication technology.

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