Low-voltage phase-to-phase low-resistance short-circuit fault location method, device, equipment and medium

Abstract

The embodiment of the present invention discloses a method for locating a low-voltage phase-to-phase low-resistance short-circuit fault: obtaining the node voltage and node current of each node of each phase in the normal operating state of the distribution station area; determining the normal impedance value of each line section between each node of the phase in the normal state, and then determining the characteristic impedance section of each line section; monitoring the current of each phase at the outlet of the distribution transformer, determining the voltage vector and current vector of the two faulty phases when the phase-to-phase low-resistance short-circuit fault occurs, and determining the fault characteristic impedance of the distribution transformer outlet from the fault point; according to the characteristic impedance section and fault characteristic impedance of each line section, determining the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short-circuit fault occurs. This scheme monitors the low-voltage phase-to-phase low-resistance short-circuit fault in the distribution station area in real time and locates it, quickly locates the fault point, supports the power grid operation and maintenance personnel to quickly discover and determine the fault point, shortens the maintenance time, prevents the fault from expanding, ensures the power supply safety of the station area, and improves the power supply reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network fault location, and in particular to a method, device, equipment and medium for locating a low-voltage phase-to-phase low-resistance short-circuit fault. Background Art

[0002] Phase-to-phase low-resistance short-circuit fault is one of the common electrical faults in distribution substations. Phase-to-phase faults cause regional power outages, affecting users' normal power consumption. If the circuit breaker cannot trip correctly, it may also cause fires and other accidents. Substation lines may use cables, overhead lines, etc., and faults are difficult to troubleshoot. Identifying and accurately locating phase-to-phase low-resistance short-circuit faults in distribution substations is of great significance to improving the reliability and safety of power systems.

[0003] Fault identification and location are the primary and necessary steps in distribution network fault handling. There are many methods, such as constructing an improved matrix to locate the fault interval and establishing an optimization model to make fault-tolerant judgments on fault location. However, although this method has outstanding fault-tolerant performance, the accuracy of fault location is relatively insufficient. Another method is to establish a causal relationship model between the feeder status and the current overlimit, and further use the Bayesian probability model to determine the fault section. However, the positioning accuracy of this method is closely related to the parameters of the probability model and is difficult to be generally applied. It can be seen that although there are many methods for locating faults in distribution station areas, there is still no simple, reliable, and accurate fault location method. Summary of the invention

[0004] Based on this, it is necessary to propose a low-voltage phase-to-phase low-resistance short-circuit fault locating method, device, equipment and storage medium to address the above problems.

[0005] To achieve the above objectives, the present application provides a first aspect of a low-voltage phase-to-phase low-resistance short-circuit fault locating method, the method comprising:

[0006] Obtain the voltage and current of each node of each phase in the normal operating state of the distribution station area, wherein the nodes include the head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located;

[0007] Determine the normal impedance value of each line section between each node of the phase under normal operation according to the node voltage and node current of each node of each phase under normal operation of the distribution station area;

[0008] Determining a characteristic impedance interval of each line interval according to a normal impedance value of each line interval between the nodes;

[0009] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs;

[0010] Acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs;

[0011] Determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault;

[0012] According to the characteristic impedance interval of each line section and the fault characteristic impedance, the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs is determined.

[0013] In some embodiments, the normal impedance value of each line section is based on Determine, where Z Lx is the normal impedance value of the line section Lx, U Np is the node voltage of the node on the power supply side of the line section; U Nn is the node voltage of the load side node of the line section, I Nx is the node current of the node on the load side of the line section.

[0014] In some implementations, determining the characteristic impedance interval of each line interval according to the normal impedance value of each line interval between the nodes includes:

[0015] Set the characteristic impedance value of the head node to zero;

[0016] Determine the algebraic sum of the normal impedance values ​​of all line sections between any node among the other nodes and the head node as the characteristic impedance value of the node;

[0017] The characteristic impedance values ​​of the nodes at both ends of each line section are obtained, and the characteristic impedance sections of each line section are formed by the characteristic impedance values ​​of the nodes at both ends of each line section.

[0018] In some implementations, the real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs includes:

[0019] Monitor the current of each phase at the outlet of the distribution transformer in real time. If the sudden increase in current of two phases exceeds the phase-to-phase low-resistance short-circuit fault mutation threshold, and the sudden increase in current of the remaining phase does not exceed the ground fault current mutation threshold, it is judged that a phase-to-phase low-resistance short-circuit fault occurs in the distribution station area line, and the two phases whose sudden increase in current exceeds the phase-to-phase low-resistance short-circuit fault mutation threshold are the two faulty phases.

[0020] In some implementations, determining the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two faulty phases specifically includes:

[0021] according to Determine the fault characteristic impedance of the distribution transformer outlet from the fault point, where: are the fault phase voltage vectors of the two fault phases, are the fault phase current vectors of the two fault phases, Z g is the fault characteristic impedance of the distribution transformer outlet at the fault point.

[0022] In some implementations, determining the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs according to the characteristic impedance section of each line section and the fault characteristic impedance includes:

[0023] The characteristic impedance intervals of the line sections are compared with the fault characteristic impedance, and it is determined that the line section corresponding to the characteristic impedance interval in which the fault characteristic impedance is located is the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs.

[0024] To achieve the above-mentioned purpose, the second aspect of the present application provides a low-voltage phase-to-phase low-resistance short-circuit fault locating device, the device comprising:

[0025] A first acquisition unit is used to acquire the voltage and current of each node of each phase in the normal operating state of the distribution station area, wherein the various nodes include the head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located;

[0026] A normal impedance value determination unit, used to determine the normal impedance value of each line section between each node of the phase under normal state according to the node voltage and node current of each node of each phase under normal operation of the distribution station area;

[0027] A characteristic impedance interval determining unit, configured to determine a characteristic impedance interval of each line interval according to a normal impedance value of each line interval between the nodes;

[0028] A monitoring unit, used for real-time monitoring of the current of each phase at the outlet of the distribution transformer, and determining the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs;

[0029] A second acquisition unit is used to acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs;

[0030] A fault characteristic impedance determination unit, used to determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault;

[0031] The fault point determination unit is used to determine the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs according to the characteristic impedance section of each line section and the fault characteristic impedance.

[0032] In some embodiments, the fault point determination unit is further used to compare the characteristic impedance interval of each line section with the fault characteristic impedance, and determine that the line section corresponding to the characteristic impedance interval in which the fault characteristic impedance is located is the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs.

[0033] To achieve the above-mentioned object, the third aspect of the present application provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the following steps:

[0034] Obtain the voltage and current of each node of each phase in the normal operating state of the distribution station area, wherein the nodes include the head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located;

[0035] Determine the normal impedance value of each line section between each node of the phase under normal operation according to the node voltage and node current of each node of each phase under normal operation of the distribution station area;

[0036] Determining a characteristic impedance interval of each line interval according to a normal impedance value of each line interval between the nodes;

[0037] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs;

[0038] Acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs;

[0039] Determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault;

[0040] According to the characteristic impedance interval of each line section and the fault characteristic impedance, the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs is determined.

[0041] To achieve the above-mentioned purpose, the fourth aspect of the present application provides a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the following steps:

[0042] Obtain the voltage and current of each node of each phase in the normal operating state of the distribution station area, wherein the nodes include the head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located;

[0043] Determine the normal impedance value of each line section between each node of the phase under normal operation according to the node voltage and node current of each node of each phase under normal operation of the distribution station area;

[0044] Determining a characteristic impedance interval of each line interval according to a normal impedance value of each line interval between the nodes;

[0045] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs;

[0046] Acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs;

[0047] Determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault;

[0048] According to the characteristic impedance interval of each line section and the fault characteristic impedance, the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs is determined.

[0049] The embodiments of the present invention have the following beneficial effects:

[0050] The present invention obtains the voltage and current of each node of each phase in the normal operating state of the distribution station area according to the user electric meter in the distribution station area; determines the normal impedance value of each line section between the nodes of the phase in the normal state, and then determines the characteristic impedance section of each line section; monitors the current of each phase at the outlet of the distribution transformer in real time, determines the voltage vector and current vector of the two faulty phases when the phase-to-phase low-resistance short-circuit fault occurs, and determines the fault characteristic impedance of the distribution transformer outlet from the fault point; determines the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short-circuit fault occurs according to the characteristic impedance section and the fault characteristic impedance of each line section, solves the problems of insufficient accuracy and poor universality of the current distribution station area fault location method, and can monitor the phase-to-phase fault of 0.4kV low-voltage line in real time and locate it, can quickly locate the fault point, support power grid operation and maintenance personnel to quickly discover hidden faults, determine the fault point, shorten the maintenance time and power outage time, and improve power supply reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] in:

[0053] Figure 1 A schematic diagram of a flow chart of a method for locating a low-voltage phase-to-phase low-resistance short-circuit fault in one embodiment;

[0054] Figure 2 is a structural diagram of a distribution network in an embodiment;

[0055] Figure 3 1 is a structural diagram of a low-voltage phase-to-phase low-resistance short-circuit fault locating device in one embodiment;

[0056] Figure 4 is a schematic diagram of the structure of a computer device in one embodiment;

[0057] Figure 5 Schematic diagram of the structure of a computer-readable storage medium in one embodiment. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] In the embodiment of the present application, a method for locating a low-voltage phase-to-phase low-resistance short-circuit fault is provided. Figure 1 , Figure 1 1 is a flow chart of a method for locating a low-voltage phase-to-phase low-resistance short-circuit fault in an embodiment. The method for locating a low-voltage phase-to-phase low-resistance short-circuit fault includes steps S1 to S7.

[0060] Step S1, obtaining the voltage and current of each node of each phase in the normal operating state of the distribution station area, wherein the nodes include the head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located;

[0061] Specifically, a positioning terminal is set at the outlet of the distribution transformer, and the outlet of the distribution transformer where the positioning terminal is located is used as the head node. The node voltage of the head node is measured by the positioning terminal, and the voltage and current of each node of each phase are obtained. Other nodes are equipped with smart meters, and the voltage value of the smart meter of each phase and each node is recorded as the node voltage of the node. Except for the head node, the node current of each phase and each node is calculated. The node current is the algebraic sum of the currents measured by the smart meters of the phase, the node and all nodes on the load side of the node.

[0062] Step S2, determining the normal impedance value of each line section between each node of the phase under normal state according to the node voltage and node current of each node of each phase under normal operation of the distribution station area;

[0063] In some embodiments, the normal impedance value of each line section is based on Determine, where Z Lx is the normal impedance value of the line section Lx, U Np is the node voltage of the node on the power supply side of the line section; U Nn is the node voltage of the load side node of the line section, I Nx Specifically, for the node current of the load-side node of the line section, the collected sensor data are first time-aligned to ensure the consistency of the data, and then operations such as standardization, filtering and denoising, and feature engineering are performed to improve the data quality.

[0064] Step S3, determining the characteristic impedance interval of each line interval according to the normal impedance value of each line interval between the nodes;

[0065] In some implementations, determining the characteristic impedance interval of each line interval according to the normal impedance value of each line interval between the nodes includes:

[0066] Set the characteristic impedance value of the head node to zero;

[0067] Determine the algebraic sum of the normal impedance values ​​of all line sections between any node among the other nodes and the head node as the characteristic impedance value of the node;

[0068] The characteristic impedance values ​​of the nodes at both ends of each line section are obtained, and the characteristic impedance sections of each line section are formed by the characteristic impedance values ​​of the nodes at both ends of each line section.

[0069] Step S4, real-time monitoring of the current of each phase at the outlet of the distribution transformer, and determining the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs;

[0070] In some implementations, the real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs includes:

[0071] Monitor the current of each phase at the outlet of the distribution transformer in real time. If the sudden increase in current of two phases exceeds the phase-to-phase low-resistance short-circuit fault mutation threshold, and the sudden increase in current of the remaining phase does not exceed the ground fault current mutation threshold, it is judged that a phase-to-phase low-resistance short-circuit fault occurs in the distribution station area line, and the two phases whose sudden increase in current exceeds the phase-to-phase low-resistance short-circuit fault mutation threshold are the two faulty phases.

[0072] Step S5, obtaining the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs;

[0073] Step S6, determining the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two faulty phases;

[0074] In some implementations, determining the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two faulty phases specifically includes:

[0075] according to Determine the fault characteristic impedance of the distribution transformer outlet from the fault point, where: are the fault phase voltage vectors of the two fault phases, are the fault phase current vectors of the two fault phases, Z g is the fault characteristic impedance of the distribution transformer outlet at the fault point.

[0076] Step S7, determining the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs according to the characteristic impedance section of each line section and the fault characteristic impedance;

[0077] In some implementations, determining the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs according to the characteristic impedance section of each line section and the fault characteristic impedance includes:

[0078] The characteristic impedance intervals of the line sections are compared with the fault characteristic impedance, and it is determined that the line section corresponding to the characteristic impedance interval in which the fault characteristic impedance is located is the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs.

[0079] The low-voltage phase-to-phase low-resistance short-circuit fault locating method proposed in the present invention is used. With the rapid development of distribution networks, as smart meters have relatively comprehensively covered most distribution stations, the present invention proposes to use the voltage and current data of smart meters in distribution stations to accurately locate faults according to the impedance characteristics of the line section. This is a simple, reliable, highly accurate and low-cost new fault locating method, which solves the problems of insufficient accuracy and poor universality of current distribution station fault locating methods. It can monitor the phase-to-phase fault conditions of 0.4kV low-voltage lines in real time and locate them, and can quickly locate the fault point, supporting power grid operation and maintenance personnel to quickly discover hidden faults and determine the fault point, shorten maintenance time and power outage time, and improve power supply reliability.

[0080] The following is a further description of the low-voltage phase-to-phase low-resistance short-circuit fault location method of the present application in conjunction with specific embodiments:

[0081] according to Figure 2 The distribution network structure diagram shown in the figure uses PSCAD simulation software to establish a 0.4kV distribution system model, including 5 sections of 0.4kV lines, 5 0.4kV loads, the distribution transformer capacity is set to 500kVA, the rated current is 721A, the length of the 5 sections of 0.4kV lines is 50m, and each line is divided into two sections on average. The line model reference model is JKLYJ-50 0.4kV low-voltage overhead conductor setting. The impedance parameter of this model conductor is 0.67+j0.29Ω / km. In this example, the line length is 50m, and the parameters of each section of the line are 0.0336+j0.0146Ω. The load model is a series connection of resistance and reactance, and the three-phase load is the same. In this example, the load power factor is 0.8.

[0082] A positioning terminal is installed at N0, and a smart meter is installed at each of the N1 to N5 nodes. The entire line is divided into five line sections: Line 1 to Line 5.

[0083] Set the middle position of Line3 interval to have an AB phase interphase low-resistance short-circuit fault, the transition resistance is 0.01Ω, and the interphase low-resistance short-circuit fault current mutation threshold is set to 10% of the distribution transformer rated current, that is, 72.1A. According to the low-voltage interphase low-resistance short-circuit fault location method of the present application, the fault location process includes:

[0084] In normal operation, the node voltage and node current of each node of each phase in the normal operation state of the distribution station area are obtained, as shown in Table 1:

[0085] Table 1: The voltage, current and node current of each node

[0086] node Node voltage (V) Meter current (A) Node current (A) N0 229.38 56.32 / N1 227.35 11.39 56.32 N2 225.72 11.31 44.93 N3 224.51 11.24 33.63 N4 223.70 11.20 22.39 N5 223.29 11.18 11.18

[0087] In the above table, the currents of each node are

[0088] According to the node voltage and node current of each node of each phase under the normal operation state of the distribution station area, the normal impedance value of the line section under the normal state of each line section Line1-Line5 is determined, as shown in Table 2:

[0089] Table 2: Normal impedance values ​​of each line section:

[0090] Line segment Impedance modulus (Ω) Line1 0.036 Line2 0.036 Line3 0.036 Line4 0.036 Line5 0.036

[0091] Calculate the characteristic impedance value of each node, as shown in Table 3:

[0092] Table 3: Characteristic impedance values ​​of each node

[0093] node Impedance modulus (Ω) N0 0 N1 0.036 N2 0.072 N3 0.108 N4 0.144

[0094] in,

[0095] Calculate the characteristic impedance interval of each line section, as shown in Table 4:

[0096] Table 4: Characteristic impedance range of each line segment

[0097] Line segment Impedance modulus (Ω) Line1 0～0.036 Line2 0.036～0.072 Line3 0.072～0.108 Line4 0.108～0.144

[0098] By monitoring the current of each phase, when a low-resistance short-circuit fault occurs between phases AB, the currents of phases AB reach 1753A and 1749A respectively, exceeding the fault current threshold (the threshold is set to 793A, i.e. 1.1 times the rated current of the distribution transformer). The current of phase C is 56A, so it is determined to be a phase-to-phase fault between phases AB.

[0099] Measure the voltage vector and current vector of each phase at N0, and the voltage and current vector values ​​of the fault phase, as shown in Table 5:

[0100] Table 5 Fault phase voltage and current vectors at the distribution transformer outlet N0

[0101] Phase A Phase B Voltage (V) 226.23∠-69.95° 179.04∠177.94° Current (A) 1753.6∠-83.67° 1749.7∠98.17°

[0102] Calculate the fault characteristic impedance of the distribution transformer outlet distance to the fault point:

[0103]

[0104] Since the fault impedance Z of the distribution transformer outlet positioning terminal is far from the fault point g =0.096Ω, the fault impedance is located in the characteristic impedance range of 0.072~0.108 of line segment Line3, so it is judged that the fault point is located in line segment Line3.

[0105] In the embodiment of the present application, a low-voltage phase-to-phase low-resistance short-circuit fault locating device is provided. Figure 3 , Figure 3 A structural diagram of a low-voltage phase-to-phase low-resistance short-circuit fault locating device in one embodiment, the low-voltage phase-to-phase low-resistance short-circuit fault locating device comprising: a first acquisition unit 201, a normal impedance value determination unit 202, a characteristic impedance interval determination unit 203, a monitoring unit 204, a second acquisition unit 205, a fault characteristic impedance determination unit 206 and a fault point determination unit 207.

[0106] Wherein, the first acquisition unit 201 is configured to obtain the voltage and current of each node of each phase in the normal operating state of the distribution station area, wherein the various nodes include the head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located;

[0107] The normal impedance value determination unit 202 is configured to determine the normal impedance value of each line section between each node of the phase under normal state according to the node voltage and node current of each node of each phase under normal operation of the distribution station area;

[0108] The characteristic impedance interval determining unit 203 is configured to determine the characteristic impedance interval of each line interval according to the normal impedance value of each line interval between the nodes;

[0109] The monitoring unit 204 is configured to monitor the current of each phase at the outlet of the distribution transformer in real time, and determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs;

[0110] The second acquisition unit 205 is configured to acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs;

[0111] A fault characteristic impedance determination unit 206 is configured to determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault;

[0112] The fault point determination unit 207 is configured to determine the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs according to the characteristic impedance section of each line section and the fault characteristic impedance.

[0113] In some implementations, the normal impedance value determination unit 202 is further configured to determine the normal impedance value of each line section according to Determine, where Z Lx is the normal impedance value of the line section Lx, U Np is the node voltage of the node on the power supply side of the line section; U Nn is the node voltage of the load side node of the line section, I Nx is the node current of the node on the load side of the line section.

[0114] In some implementations, the fault characteristic impedance determination unit 206 is further configured to set the characteristic impedance value of the head node to zero;

[0115] Determine the algebraic sum of the normal impedance values ​​of all line sections between any node among the other nodes and the head node as the characteristic impedance value of the node;

[0116] The characteristic impedance values ​​of the nodes at both ends of each line section are obtained, and the characteristic impedance sections of each line section are formed by the characteristic impedance values ​​of the nodes at both ends of each line section.

[0117] In some embodiments, the monitoring unit 204 is also configured to monitor the current of each phase at the outlet of the distribution transformer in real time. If the current sudden increase of two phases exceeds the phase-to-phase low-resistance short-circuit fault mutation threshold, and the current sudden increase of the remaining phase does not exceed the ground fault current mutation threshold, it is judged that a phase-to-phase low-resistance short-circuit fault occurs in the distribution station area line, and the two phases whose current sudden increase exceeds the phase-to-phase low-resistance short-circuit fault mutation threshold are the two faulty phases.

[0118] In some implementations, the fault characteristic impedance determination unit 206 is further configured to: Determine the fault characteristic impedance of the distribution transformer outlet from the fault point, where: are the fault phase voltage vectors of the two fault phases, are the fault phase current vectors of the two fault phases, Z g is the fault characteristic impedance of the distribution transformer outlet at the fault point.

[0119] In some embodiments, the fault point determination unit 207 is further configured to compare the characteristic impedance interval of each line section with the fault characteristic impedance, and determine that the line section corresponding to the characteristic impedance interval in which the fault characteristic impedance is located is the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs.

[0120] For other details about how each module in the low-voltage phase-to-phase low-resistance short-circuit fault locating device implements the above-mentioned technical solution, please refer to the description of the low-voltage phase-to-phase low-resistance short-circuit fault locating method provided above, which will not be repeated here.

[0121] In an embodiment of the present application, a computer device is provided. Figure 4 , Figure 4 3 is a schematic diagram of the structure of a computer device in an embodiment. The device includes a memory 301 and a processor 302. The memory 301 stores a computer program. When the computer program is executed by the processor 302, the processor 302 performs the following steps:

[0122] Obtain the voltage and current of each node of each phase in the normal operating state of the distribution station area, wherein the nodes include the head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located;

[0123] Determine the normal impedance value of each line section between each node of the phase under normal operation according to the node voltage and node current of each node of each phase under normal operation of the distribution station area;

[0124] Determining a characteristic impedance interval of each line interval according to a normal impedance value of each line interval between the nodes;

[0125] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs;

[0126] Acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs;

[0127] Determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault;

[0128] According to the characteristic impedance interval of each line section and the fault characteristic impedance, the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs is determined.

[0129] Among them, the processor 302 can also be called a CPU (Central Processing Unit), and the processor 302 may be an integrated circuit chip with signal processing capabilities; the processor 302 can also be a general-purpose processor, DSP (Digital Signal Process), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, among which the general-purpose processor can be a microprocessor or the processor 302 can also be any conventional processor, etc.

[0130] In an embodiment of the present application, a computer readable storage medium is provided. Figure 5 , Figure 5 The structure diagram of a computer-readable storage medium in an embodiment is a schematic diagram, on which a readable computer program 401 is stored; wherein the computer program 401 may be stored in the above storage medium in the form of a software product, and includes a number of instructions for causing a computer device (which may be a personal computer, a server machine, or a network device, etc.) or a processor to perform the following steps:

[0131] Obtain the voltage and current of each node of each phase in the normal operating state of the distribution station area, wherein the nodes include the head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located;

[0132] Determine the normal impedance value of each line section between each node of the phase under normal operation according to the node voltage and node current of each node of each phase under normal operation of the distribution station area;

[0133] Determining a characteristic impedance interval of each line interval according to a normal impedance value of each line interval between the nodes;

[0134] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs;

[0135] Acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs;

[0136] Determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault;

[0137] According to the characteristic impedance interval of each line section and the fault characteristic impedance, the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs is determined.

[0138] The aforementioned storage media include: USB flash drives, mobile hard disks, magnetic disks or optical disks, ROM (Read-Only Memory), RAM (Random Access Memory), and other media that can store program codes, or terminal devices such as computers, service machines, mobile phones, and tablets.

[0139] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0140] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0141] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for locating a low-voltage phase-to-phase low-resistance short-circuit fault, characterized in that: The method comprises: Obtain the node voltage and node current of each node of each phase in the normal operating state of the distribution station area, wherein each node includes the head node and other nodes, the node voltage and node current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of other nodes is the first household meter voltage under the node, and the node current of other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located; Determine the normal impedance value of each line section between each node of the phase under normal operation according to the node voltage and node current of each node of each phase under normal operation of the distribution station area; Determining a characteristic impedance interval of each line interval according to a normal impedance value of each line interval between the nodes; Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs; Acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs; Determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault; According to the characteristic impedance interval of each line section and the fault characteristic impedance, the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs is determined.

2. The low-voltage phase-to-phase low-resistance short-circuit fault locating method according to claim 1 is characterized in that: The normal impedance value of each line section is based on Among them, Z Lx is the normal impedance value of the line section Lx, U Np is the node voltage of the node on the power supply side of the line section; U Nn is the node voltage of the load side node of the line section, I Nx is the node current of the node on the load side of the line section.

3. The low-voltage phase-to-phase low-resistance short-circuit fault locating method according to claim 2 is characterized in that: The determining the characteristic impedance interval of each line interval according to the normal impedance value of each line interval between the nodes includes: Set the characteristic impedance value of the head node to zero; Determine the algebraic sum of normal impedance values ​​of all line sections between any node among the other nodes and the head node as the characteristic impedance value of the node; The characteristic impedance values ​​of the nodes at both ends of each line section are obtained, and the characteristic impedance sections of each line section are formed by the characteristic impedance values ​​of the nodes at both ends of each line section.

4. The low-voltage phase-to-phase low-resistance short-circuit fault locating method according to claim 3 is characterized in that: The real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs includes: Monitor the current of each phase at the outlet of the distribution transformer in real time. If the sudden increase in current of two phases exceeds the phase-to-phase low-resistance short-circuit fault mutation threshold, and the sudden increase in current of the remaining phase does not exceed the phase-to-phase low-resistance short-circuit fault mutation threshold, it is judged that a phase-to-phase low-resistance short-circuit fault occurs in the distribution station line, and the two phases whose sudden increase in current exceeds the phase-to-phase low-resistance short-circuit fault mutation threshold are the two faulty phases.

5. The low-voltage phase-to-phase low-resistance short-circuit fault locating method according to claim 4 is characterized in that: Determining the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault specifically includes: according to Determine the fault characteristic impedance of the distribution transformer outlet from the fault point, where: are the fault phase voltage vectors of the two fault phases, are the fault phase current vectors of the two fault phases, Z g is the fault characteristic impedance of the distribution transformer outlet at the fault point.

6. The low-voltage phase-to-phase low-resistance short-circuit fault locating method according to claim 4, characterized in that: The determining, according to the characteristic impedance interval of each line interval and the fault characteristic impedance, the line interval where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs, comprises: The characteristic impedance intervals of the line sections are compared with the fault characteristic impedance, and it is determined that the line section corresponding to the characteristic impedance interval in which the fault characteristic impedance is located is the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs.

7. A low-voltage phase-to-phase low-resistance short-circuit fault locating device, characterized in that: The device comprises: A first acquisition unit is used to acquire the node voltage and node current of each node of each phase in the normal operation state of the distribution station area, wherein each node includes a head node and other nodes, the voltage and current of the head node are the voltage and current at the outlet of the distribution transformer, the node voltage of the other nodes is the first household meter voltage under the node, and the current of the other nodes is the algebraic sum of the household meter currents of the node and all nodes on the load side of the node on the phase where the node is located; A normal impedance value determination unit, used to determine the normal impedance value of each line section between each node of the phase under normal state according to the node voltage and node current of each node of each phase under normal operation of the distribution station area; A characteristic impedance interval determination unit, configured to determine a characteristic impedance interval of each line interval according to a normal impedance value of each line interval between the nodes; A monitoring unit, used for real-time monitoring of the current of each phase at the outlet of the distribution transformer, and determining the two faulty phases when a phase-to-phase low-resistance short-circuit fault occurs; A second acquisition unit is used to acquire the fault phase voltage vector and the fault phase current vector of the two phases of the fault when the inter-phase low-resistance short circuit fault occurs; A fault characteristic impedance determination unit, used to determine the fault characteristic impedance of the distribution transformer outlet from the fault point according to the fault phase voltage vector and the fault phase current vector of the two phases of the fault; The fault point determination unit is used to determine the line section where the fault point is located when a low-voltage phase-to-phase low-resistance short circuit fault occurs according to the characteristic impedance section of each line section and the fault characteristic impedance.

8. The low-voltage phase-to-phase low-resistance short-circuit fault locating device according to claim 7, characterized in that: The fault point determination unit is further used to compare the characteristic impedance interval of each line section with the fault characteristic impedance, and determine that the line section corresponding to the characteristic impedance interval where the fault characteristic impedance is located is the line section where the fault point is located when the low-voltage phase-to-phase low-resistance short circuit fault occurs.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method according to any one of claims 1 to 6.

10. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 6.

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