A power distribution network broken line fault positioning method and system

Abstract

The present application belongs to the technical field of broken line fault diagnosis, and particularly relates to a power distribution network broken line fault positioning method and system. For a certain line, if it is found that the current of a certain phase of the line drops to zero, other phases change little, the line with the upper node of the line as the lower node shows a downward trend, other lines with the upper node of the line as the lower node change little, and the broken line phase current of the line with the lower node of the line as the upper node drops to zero, it is determined that the broken line phase of the line has a broken line fault at the current time. The whole method does not need complex parameter calculation, needs less characteristic quantity, has a simple principle algorithm, and is faster in calculation, and has higher real-time performance in broken line fault judgment. Meanwhile, a simple and implementable power distribution network broken line fault system is provided, which provides hardware support for the above method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of broken line fault diagnosis, and particularly relates to a power distribution network broken line fault positioning method and system. BACKGROUND

[0002] In a power system, a power distribution line is a key component of power transmission, and its power supply reliability and power supply quality directly affect industrial production and social economic development; the scale of a power distribution network is increasingly large and complex with the development of a city, there are numerous lines and a large number of devices with different levels in the network, and the probability of broken line in an overhead line of the power distribution network is also increasing, so that the broken line fault has become an important fault type of the power distribution network.

[0003] The broken line fault of the overhead line of the power distribution network is mainly caused by the following reasons: (1) electrical reasons, such as a damaged line due to short circuit or overload, etc., causing the damaged part to heat and burn the conductor, or uneven electric field distribution causing the broken line; (2) external force reasons, such as trees being blown down by wind and pulling the line, or objects falling and crushing the line, etc.; (3) natural disaster reasons, such as lightning arc, frozen rain and ice, etc., causing the broken line; (4) human reasons, such as poor construction quality, disorderly wiring and stealing of fittings, etc., causing the broken line. After the broken line fault of the power distribution network line occurs, obvious three-phase voltage and current imbalance phenomena will occur at the power supply side and the load side, causing the motor to run at a sharply reduced speed or even burn out, causing serious damage to electrical equipment and large economic losses; at the same time, the broken line fault may also cause electric shock of people and animals, forest fires, etc., so timely identification and elimination of the broken line fault is an important responsibility for safe operation of the power distribution network line.

[0004] The operation condition of the power distribution network is complex, and the broken line fault includes three types of broken line not grounded fault, broken line power supply side grounded fault and broken line load side grounded fault according to the actual broken line condition. At present, the power distribution network is relatively mature in handling short circuit and power supply grounded fault, but the monitoring and identification of the other two types of broken line fault are still relatively insufficient, and the handling of the broken line fault mainly relies on manual line inspection, resulting in a long time for fault confirmation and handling. With the increasing attention to the broken line fault, some scholars have proposed some broken line fault detection methods, but most of them rely on complex phase and zero sequence, negative sequence component calculation, and the algorithm is complex, and a large number of electrical characteristic quantities are required, which has certain limitations.

[0005] In summary, the broken line fault of the power distribution network is relatively complex, and its fault characteristics are not obvious. Based on the existing relay protection and short-circuit grounding fault positioning method, a relatively complex calculation method is mostly used, including the broken line fault judgment method based on the voltage, current phasor relationship or sequence component characteristic relationship, which is not suitable for the identification and positioning of the broken line fault, and there is a lack of simple, practical, economical and reliable broken line fault identification and protection method. Therefore, how to realize the rapid detection and positioning of the broken line fault of the power distribution network and improve the practicability, economy and reliability of the detection method is a problem that needs to be solved by the technical personnel in the field. SUMMARY

[0006] The purpose of the present application is to provide a power distribution network broken line fault positioning method and system to solve the problem of complex broken line fault positioning method in the prior art.

[0007] To solve the above technical problems, the technical solutions provided by the present application and the beneficial effects corresponding to the technical solutions are as follows:

[0008] The power distribution network broken line fault positioning method of the present application comprises the following steps:

[0009] 1) Obtain the three-phase current of each section of the power distribution network line; wherein, a plurality of nodes are arranged on the power distribution network line, and all nodes divide the power distribution network line into a plurality of sections. For a section, if a node is connected upstream of the section, it is called an upper node of the section, and if a node is connected downstream of the section, it is called a lower node of the section;

[0010] 2) For a certain section, determine whether the current phase or phases of the certain section at the current time is less than the set zero drop threshold value. If the phenomenon occurs, define the phase less than the set zero drop threshold value as a broken line phase, and determine whether the difference between the non-broken line phase current at the current time and the non-broken line phase current at the previous time is within the set difference range. If it is within the set difference range, define the certain section as a line to be diagnosed, and perform step 3) for further judgment and processing;

[0011] 3) Determine whether the following judgment conditions are met. If they are met, it is determined that the broken line phase of the line to be diagnosed has a broken line fault at the current time; the judgment conditions include:

[0012] Condition 1: the current broken line phase current of the line with the upper node of the line to be diagnosed as the lower node is less than the previous broken line phase current;

[0013] Condition 2: there is a line other than the line to be diagnosed with the upper node of the line to be diagnosed as the upper node, and the difference between the current and previous currents of the other line is within the set difference range;

[0014] Condition 3, in the case where there is a line with the lower node of the line to be diagnosed as the upper node, the broken-phase current of the line with the lower node of the line to be diagnosed as the upper node is less than the set zero-out threshold.

[0015] The beneficial effects of the above technical solutions are: the method of the application is designed by taking advantage of the characteristics that the power distribution network line has greater influence on the power distribution network line downstream of the fault point and has smaller influence on the power distribution network line upstream of the fault point when the power distribution network line has a broken line fault, the method collects and judges the three-phase current of the power distribution network line, and can quickly find the broken phase and the specific line that has a broken line fault, the entire method does not require complex parameter calculation, compared with the existing broken line protection technology based on voltage, current phasor relationship or sequence component characteristic relationship, the required characteristic quantity is less, the principle algorithm is simple, the calculation is faster, and the broken line fault judgment has higher real-time performance.

[0016] Further, in order to accurately locate the fault position, after it is determined that the line to be diagnosed has a broken line fault at the current time, the line to be diagnosed is further photographed to determine the specific geographic position of the broken line fault in the line to be diagnosed.

[0017] Further, in step 2), the difference between the non-broken-phase current of the certain line at the current time and the non-broken-phase current at the previous time is calculated by the following method: calculating the ratio of the difference between the non-broken-phase current of the certain line at the current time and the non-broken-phase current at the previous time to the non-broken-phase current at the current time.

[0018] Further, in step 3), the difference between the current and the previous current of the other line is calculated by the following method: calculating the ratio of the difference between the current and the previous current of the other line to the current of the other line.

[0019] Further, the set difference range is less than 10%.

[0020] The power distribution network broken line fault positioning system of the application comprises a remote positioning module and a branch control module corresponding to the upper node of the power distribution network line, each branch control module is in communication connection with the remote positioning module.

[0021] Each branch control module comprises a core control unit, a line collection unit and a power supply unit; the power supply unit is in power supply connection with the core control unit.

[0022] The core control unit is connected with a sampling connection line collection unit; if the node is a first node, the first node is a node on a line upstream of the first node as a lower node and a power supply side, the line collection unit corresponding to the node includes a current sensor arranged on the line with the first node as an upper node for collecting three-phase current on the line, and a current sensor arranged on the line with the first node as a lower node for collecting three-phase current on the line; if the node is not the first node, the line collection unit corresponding to the node includes a current sensor arranged on the line with the corresponding node as an upper node for collecting three-phase current on the line;

[0023] The remote positioning module includes an industrial server for realizing the power distribution network broken line fault positioning method according to the acquired data.

[0024] The beneficial effects of the above technical scheme are that: in order to cooperate with the realization of the power distribution network broken line fault positioning method, the system is designed, and a plurality of branch control modules are designed in the system, each branch control module is responsible for collecting the change of part of the line current, the division of labor is clear, and hardware support is provided for the realization of the power distribution network broken line fault positioning method, and the reliable operation of the entire system is ensured.

[0025] Further, in order to accurately locate the fault position, each branch control module further includes an image collection unit corresponding to a node on the power distribution network line, and the image collection unit is used for shooting the to-be-diagnosed line.

[0026] Further, in order to ensure reliable operation of the system and save energy, the power supply unit includes a solar main power supply and a backup battery, and the solar main power supply is connected with the backup battery for power supply.

[0027] Further, in order to realize reliable communication between the branch control module and the remote positioning module, each branch control module is connected with the remote positioning module in a narrowband Internet of Things communication mode.

[0028] Further, in order to facilitate the staff to check the fault position, the remote positioning module further includes a man-machine interaction unit and a graphic display unit, both of which are connected with the industrial server. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the power distribution network broken line fault positioning system of the application;

[0030] Figure 2 is an electrical principle schematic diagram of the power distribution network broken line fault positioning system of the application;

[0031] Figure 3 is a communication network principle schematic diagram of the power distribution network broken line fault positioning system of the application;

[0032] Figure 4 is the schematic diagram of the branch control module of the application;

[0033] Figure 5 is the schematic diagram of another power distribution network broken line fault locating system of the application.

[0034] Wherein, 1-remote positioning module, 2-n branch control module, 10-industrial server, 11-graphical display unit, 12-human-computer interaction unit, 20-core control unit, 21-line acquisition unit, 22-image acquisition unit, 23-power supply unit, 210-218-acquisition components, 220-high-definition camera component, 221-pan-tilt control component, 230-power management component, 231-backup power supply, 232-solar main power supply. DETAILED DESCRIPTION

[0035] The application utilizes the characteristics that the power distribution network line downstream of the fault point is greatly affected while the power distribution network line upstream of the fault point is less affected when the power distribution network line occurs a broken line fault, designs a power distribution network broken line fault locating method of the application, and simultaneously provides a power distribution network broken line fault locating system for realizing the method. The power distribution network broken line fault locating system and the power distribution network broken line fault locating method of the application are further described in detail below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the application, and are not a limitation of the application.

[0036] System embodiment:

[0037] The power distribution network broken line fault locating system embodiment of the application is aimed at the power distribution network system in the Figure 1 , n-1 nodes are arranged on the main line of the power distribution network, and the n-1 nodes are called node 1, node 2, …, node n-1 in order from left to right according to Figure 1 . The n-1 nodes are each connected with a branch line. The n-1 nodes divide the entire power distribution network line into multiple line sections. For a line section, a node connected upstream of the line section is called an upper node of the line section, and a node connected downstream of the line section is called a lower node of the line section. For example, for the line section between node 1 and node 2, node 1 is the upper node and node 2 is the lower node; for the branch line connected with node 1, there is only an upper node (i.e. node 1) without a lower node.

[0038] The fault locating system comprises a remote positioning module 1 and n-1 branch control modules, which are respectively called a branch control module 2, a second branch control module 3, …, and an n-1th branch control module n. All the branch control modules are connected with the remote positioning module 1, wherein the connection mode between the branch control module 2 and the remote positioning module 1 is as shown inFigure 2 As shown, Figure 2 In the figure, a single arrow direction is used to represent the connection cable signal transmission direction, and a double arrow is used to represent the wireless network signal transmission direction.

[0039] 1 branch control module corresponds to 1 node, and the branch control module 2 includes a line acquisition unit 21, an image acquisition unit 22, a core control unit 20 and a power supply unit 23. The branch control module 2 corresponds to node 1 (the upstream of the line of node 1 is the power supply side, so node 1 is the first node). The core control unit 20, the image acquisition unit 22 and the power supply unit 23 are installed as a whole structure on the tower at the line branch; the line acquisition unit 21 includes 9 acquisition communication components, which are respectively installed on the main line upstream of the node, the main line between the node and the node downstream of the node, and the branch line connected to the node, respectively acquiring the current at the main line a3, b3, c3, the main line a1, b1, c1 and the branch line a2, b2, c2, and the image acquisition unit 21 communicates with the core control unit 20 through 433M wireless frequency; the core control unit 20 controls the image acquisition unit 22 through the power supply and communication cable, and confirms whether to start the image acquisition action according to the instruction issued by the remote positioning module 1; the power supply unit 23 is connected with the core control unit 20 through the power supply cable, and provides power supply for the branch control module 2; the branch control module 2 communicates data with the industrial server 10 of the remote positioning module 1 through the NBIoT (Narrow Band Internet of Things) communication module embedded in the core control unit 20. The structures of other branch control modules are similar to that of the branch control module 2, but since the nodes corresponding to the other branch control modules are no longer the first node, the acquisition communication components included in the other branch control modules are 6, only including the main line between the node and the node downstream of the node and the branch line connected to the node, and no longer including the acquisition communication components on the main line upstream of the node, and the rest are the same, which will not be described here.

[0040] As shown, Figure 3 The line acquisition unit 21 is composed of 9 acquisition communication components 210-218, each of which is composed of an acquisition component and a wireless component. The acquisition component parts of the 9 acquisition communication components are completely consistent in hardware, ensuring the consistency of the acquisition accuracy, and the 9 acquisition communication components can be current sensors using wireless communication mode. The wireless components in the 9 acquisition communication components and the wireless components in the core control unit 20 need to be designed in pairs to ensure the hardware delay and clock synchronization between the line acquisition unit and the core control module. The wireless communication part of the line acquisition unit 21 and the core control unit 20 forms a short-distance wireless network, realizing the wireless communication and information interaction within the branch control module 2.

[0041] The power supply unit 23 in the branch control module 2 is composed of a backup battery 231, a solar main power supply 232 and a power management component, the power management component is responsible for charge and discharge control of the backup battery and power supply management of the core control unit 20, when the solar main power supply 232 has sufficient energy, the power supply of the core control unit 20 is provided by the solar main power supply 232, and the excess energy is distributed to the backup battery for charging, when entering night or the solar main power supply 232 has insufficient energy, the power supply of the core control unit 20 is jointly controlled by the backup battery 231 and the solar main power supply 232 through the power management component for dynamic management control; the power management component simultaneously performs overcharge and overdischarge protection management on the backup battery.

[0042] As shown in Figure 4 The image acquisition unit 22 is composed of a high-definition camera component 220 and a pan-tilt control component 221, and is connected with the core control unit 20 through cables respectively, and the core control unit adjusts the angle of the pan-tilt control component 221 and the focal length of the high-definition camera component 220 according to the control instruction of the remote positioning module 1.

[0043] The remote positioning module 1 includes an industrial server 10, a graphic display unit 11 and a man-machine interaction unit 12. The industrial server 10 is adapted to industrial applications and its network environment, has higher processing capacity, transmission speed and function expansion capacity, safety, reliability and manageability than traditional industrial computers; the industrial server 10 communicates with the graphic display unit 11 through a video cable; the graphic display unit 011 realizes graphic display of the branch control module equipment installed on the line and in the field, and the geographic coordinates of the installation position of the branch control module are displayed on the graphics. The man-machine interaction unit 12 is connected with the industrial server 10 through an IO cable, and realizes various instruction operation control of the device, device running parameter setting, graphic interface operation and inputting and the like.

[0044] The industrial server 10 in the remote positioning module 1 is composed of an NB-IoT communication component and an industrial server core component, the industrial server core component is responsible for data management of n-1 line branch modules managed by the industrial server core component, software logic control of line break and editing control of graphic data, the NB-IoT communication component is completely consistent with the NB-IoT communication component hardware design in the branch control module and forms a high-efficiency Internet of Things communication network, and realizes real-time communication data interaction between the remote positioning module and the branch control module.

[0045] Based on the above-mentioned power distribution network line break fault positioning system, a power distribution network line break fault positioning method of the application can be realized, and the method will be described in detail below.

[0046] Step one, through the acquisition communication components in each branch control module, the current data of the field operation is collected, analyzed and processed to determine the broken phase and the line to be diagnosed, and the results of the analysis and processing are uploaded to the remote positioning module 1.

[0047] For example, for branch control module 3, the 6 acquisition communication components in the branch control module collect the main line current and branch line circuit corresponding to the node in real time, and the 6 acquisition communication modules send the collected current data to the core control unit; after the core control unit corrects the wireless network transmission delay error by software, the relevant current amplitude and time scale are recorded, and the core control unit judges the current current collected by each acquisition communication component at the current time, judges whether the current current of each line at the current time is less than the set zero threshold (the zero threshold is set to be small, about equal to zero), if a phase appears zero drop phenomenon (for example, the sensor at position a1 detects that the A phase main line between node 2 and node 3 appears zero drop phenomenon), define this phase as broken phase, at this time, the non-broken phase current of this line is adjusted, and it is judged whether the difference between the non-broken phase current at the current time and the non-broken phase current at the last time is within the set difference range (for example, the sensor at position b1 detects that the B phase line current changes less than 10% compared with the last time, and the sensor at position c1 detects that the C phase line current changes less than 10% compared with the last time), if both satisfy, it is judged that the first broken line judgment condition is satisfied; define the main line between node 2 and node 3 as the line to be diagnosed. Thereafter, the core control unit uploads the analysis results including the broken phase, the line to be diagnosed, the time scale (here, the current time) to the industrial server in the remote positioning module 1 through the NB-IoT communication component.

[0048] Step two, after receiving the analysis results sent by branch control module 3, remote positioning module 1 acquires the data collected by the acquisition communication modules in branch control module 2 and branch control module 4 for further analysis and processing.

[0049] The industrial server generates a logic diagram according to the installation information of branch control module 3 to confirm the addresses of other branch control modules installed before and after branch control module 3; according to the related address, the related current amplitude information of other branch control modules installed before and after branch control module 3 at the same time scale is measured. The remote positioning module starts the second level judgment according to the measured line installation module data, logically analyzes the current information of the branch control modules installed before and after criterion 1 branch control module, and obtains the current change trend. Specifically:

[0050] Since the broken phase in step one is phase A, the line between node 2 and node 3 is the line to be diagnosed, the line with the upper node (node 2) of the line to be diagnosed as the lower node is the main line between node 1 and node 2, the other lines with the upper node (node 2) of the line to be diagnosed as the upper node are the branch lines connected at node 2, and the lines with the lower node (node 3) of the line to be diagnosed as the upper node include the main line between node 3 and node 4 (not shown in the figure) after node 3 and the branch lines connected at node 3, the current information needs to be obtained from branch control module 2 and branch control module 4 (not shown in the figure), it is judged whether the current A-phase current on the main line between node 1 and node 2 at the current time is less than the broken-phase current at the previous time (i.e. there is a downward trend) and whether the difference between the current at the current time and the current at the previous time of the branch lines connected at node 2 is within the set difference range (for example, the ratio of the difference between the current at the current time and the current at the previous time to the current at the previous time is within 10%), if both are satisfied, it is defined as satisfying the second broken-line judgment condition. Further, it is further judged whether the A-phase currents of the main line between node 3 and node 4 and the branch lines connected at node 3 are less than the set zero-drop threshold, if satisfied, it is defined as satisfying the third broken-line judgment condition. At this time, it can be determined that the main line between node 2 and node 3 has a broken-line fault at the current time.

[0051] In step three, after the broken line is determined, the closed-loop image verification work is started, the remote positioning module 1 starts the camera arranged at the branch control module 3 to collect the on-site images of different directions and focal lengths on the line, and sends the images to the graphic display unit in the remote positioning module through the NBIoT (Narrow Band Internet of Things) communication module, the remote positioning module confirms the collected broken-line images and confirms the specific position of the broken line, and completes the closed-loop verification logic of the broken-line fault.

[0052] It should be noted that in step two, if there is no other line than the line to be diagnosed with the upper node of the line to be diagnosed as the upper node, at this time, it is not necessary to further judge the difference between the current and the previous current of the other line; if there is no line with the lower node of the line to be diagnosed as the upper node, at this time, it is not necessary to further calculate whether the broken-phase current of the line with the lower node of the line to be diagnosed as the upper node is less than the set zero-drop threshold.

[0053] Moreover, in step two, the way of judging the difference between the two currents is to calculate the percentage. As another embodiment, the difference between the two currents can be directly calculated, a difference threshold is set accordingly, and the relationship between the actual difference and the difference threshold is used to judge the difference between the two currents.

[0054] In addition, the present application is further described in combination with a complex distribution network line. As shown in Fig. 4, the distribution network line includes a main line between node 1 and node 2, a main line between node 2 and node 3, a main line between node 3 and node 4, a branch line connected at node 1, a branch line connected at node 2, and a branch line connected at node 3. Figure 5The power distribution network line is shown in the figure, and the actual three-phase line is represented by a line. Five nodes k1-k5 are arranged on the entire line, nodes k1-k3 are on the main line, nodes k4-k5 are on the branch line, and the five nodes divide the entire power distribution network line into 12 lines l1-l12. For a line, the node connected upstream is called the upper node of the line, and the node connected downstream is called the lower node of the line. For example, for line l1, the upper node is node k1, and the lower node is node k2; for line l10, the upper node is node k4, and the lower node is node k5. A branch control module is arranged at each node, and there are five branch control modules. These branch control modules cooperate with a remote positioning module. A collection communication component for collecting three-phase current is arranged on each line, and for a branch control module arranged at a node, the collection communication component includes the collection communication components arranged on the lines with the node as the upper node (except for node k1). For example, for node k2, the branch control module arranged at node k2 includes the collection communication components arranged on lines l2 and l5; for node k4, the branch control module arranged at node k4 includes the collection communication components arranged on lines l10 and l7. For node k1, one end is connected to the power supply side, so the branch control module arranged at node k1 includes the collection communication components arranged on lines l4 and l1, and the collection communication component arranged on line l12.

[0055] After introducing the entire system, the method is introduced. For example, the B-phase current of line l10 drops to zero at the current time, and the A-phase and C-phase currents of line l10 at the current time are not much different from the A-phase and C-phase currents at the previous time, so further judgment and processing is continued. The upper node of line l10 is node k4, the line with node k4 as the lower node is line l4, the upper node of line l10 is node k4, the other lines with node k4 as the upper node are lines l7, and the lower node of line l10 is node k5. The lines with node k5 as the upper node include lines l9 and l11. Further judgment and processing is: if the B-phase current of line l4 at the current time has a downward trend, the three-phase currents of line l7 at the current time are not much different from those at the previous time, and the B-phase currents of lines l9 and l11 drop to zero, then it can be determined that line l10 has a broken line fault at the current time. Thereafter, the specific position of the fault in line l10 is determined by the image collection unit in the branch control module corresponding to node k4.

[0056] In summary, the present application has the following characteristics:

[0057] 1) The power distribution network broken line fault positioning method realized by the power distribution network broken line fault positioning system of the application utilizes the acquisition communication assembly in the branch control module to acquire current characteristic quantities on site, so as to realize positioning of the broken line fault section, and compared with the existing broken line protection technology based on the relationship of voltage and current phase quantities or the relationship of phase sequence component characteristics, the required characteristic quantities are less, and the principle algorithm is simple.

[0058] 2) The remote positioning module in the application can comprehensively analyze and judge the on-site equipment, the fault monitoring function is more perfect, complex parameter calculation is not required, and theoretically, the neutral point grounding mode has no influence, so compared with the prior art, the application has wide applicability.

[0059] 3) The application performs closed loop verification through the branch control module and the remote control module, the implementation manner is clear, the judgment result is more accurate, and the application has strong economy and practicability.

[0060] 4) The application reduces energy consumption of the equipment through hierarchical control, the on-site equipment operation is more reliable, and through hierarchical control, unnecessary communication data and graphic image data transmission are reduced, that is, energy loss is saved, communication flow consumption is reduced, and then the operation cost of the equipment is reduced.

[0061] Method embodiment:

[0062] The power distribution network broken line fault positioning method embodiment of the application is consistent with the power distribution network broken line fault positioning method introduced in the system embodiment, and details are not repeated here.

Claims

1. A method for locating faults in a power distribution network, characterized in that, Includes the following steps: 1) Obtain the three-phase current of each segment of the distribution network line; wherein, the distribution network line is provided with multiple nodes, and all nodes divide the distribution network line into multiple segments. For a segment, if there is a node connected upstream of the segment, the node is called the upper node of the segment; if there is a node connected downstream of the segment, the node is called the lower node of the segment. 2) For a certain line segment, determine whether the current of one or more phases of the line segment is less than the set zero-drop threshold at the current moment. If the phenomenon occurs, define the phase with the current less than the set zero-drop threshold as the disconnected phase. Then, determine whether the difference between the current of the non-disconnected phases at the current moment and the current of the non-disconnected phases at the previous moment is within the set difference range. If it is within the set difference range, define the line segment as the line to be diagnosed and execute step 3) for further judgment and processing. 3) Determine whether the following judgment conditions are met. If they are met, then determine that the broken phase of the line to be diagnosed has experienced a broken-line fault at the current moment. The judgment conditions include: Condition 1: The current phase current of the line with the upper node of the line to be diagnosed as the lower node is less than the current phase current of the line at the previous moment. Condition 2: If there are other lines besides the line to be diagnosed with the upper node of the line to be diagnosed, the difference between the current of the other lines at the current moment and the current at the previous moment is within the set difference range. Condition 3: If there is a line with the lower node of the line to be diagnosed as the upper node, the open-circuit phase current of the line with the lower node of the line to be diagnosed as the upper node is less than the set zero-drop threshold.

2. The method for locating faults in a power distribution network according to claim 1, characterized in that, After determining that the line under diagnosis has a broken circuit fault at the current moment, the line under diagnosis is further photographed to determine the specific geographical location of the broken circuit fault in the line under diagnosis.

3. The method for locating faults in a power distribution network according to claim 1, characterized in that, In step 2), the difference between the current non-disconnected phase current of a certain line segment at the current moment and the current non-disconnected phase current at the previous moment is calculated by the following method: calculate the ratio of the difference between the current non-disconnected phase current of the certain line segment at the current moment and the current non-disconnected phase current at the previous moment to the current non-disconnected phase current at the current moment.

4. The method for locating faults in a power distribution network according to claim 1, characterized in that, In step 3), the difference between the current of the other lines at the current moment and the current at the previous moment is calculated by the following method: calculate the ratio of the difference between the current of the other lines at the current moment and the current at the previous moment to the current of the other lines at the current moment.

5. The method for locating faults in a power distribution network according to claim 3 or 4, characterized in that, The specified difference range is less than 10%.

6. A power distribution network open circuit fault location system, characterized in that, It includes a remote positioning module and branch control modules corresponding to nodes on the distribution network line, with each branch control module communicating with the remote positioning module; Each branch control module includes a core control unit, a line acquisition unit, and a power supply unit; the power supply unit provides power to the core control unit. The core control unit samples and connects to the line acquisition unit; if the node is the first node, and the first node is the node upstream of the line with the first node as the lower node as the power supply side, then the line acquisition unit corresponding to the node includes a current sensor installed on the line with the first node as the upper node for acquiring the three-phase current on the line, and a current sensor installed on the line with the first node as the lower node for acquiring the three-phase current on the line. If the node is not the first node, the line acquisition unit corresponding to the node includes a current sensor installed on the line with the corresponding node as the upper node for acquiring the three-phase current on the line. The remote positioning module includes an industrial server, used to implement the power distribution network disconnection fault location method as described in any one of claims 1 to 5 based on the acquired data.

7. The power distribution network open circuit fault location system according to claim 6, characterized in that, Each branch control module also includes an image acquisition unit corresponding to a node on the distribution network line, the image acquisition unit being used to photograph the line to be diagnosed.

8. The power distribution network open circuit fault location system according to claim 6, characterized in that, The power supply unit includes a solar main power supply and a backup battery, with the solar main power supply connected to the backup battery.

9. The power distribution network open circuit fault location system according to claim 6, characterized in that, Each branch control module communicates with the remote positioning module via narrowband IoT.

10. The power distribution network open circuit fault location system according to any one of claims 6 to 9, characterized in that, The remote positioning module also includes a human-computer interaction unit and a graphics display unit, both of which are connected to an industrial server.

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