Method, device, equipment and medium for locating low-voltage phase-to-phase high-resistance fault in distribution station area

Abstract

The embodiment of the present invention discloses a method for locating low-voltage interphase high-resistance faults in a distribution station area: monitoring the current of each phase at the outlet of the distribution transformer to determine the interphase short-circuit fault; obtaining the node voltage and node current of each node of each phase under normal state and interphase short-circuit fault state respectively; determining the impedance value of each line section between each node of each phase under normal state and the impedance value of each line section between each node of each phase under fault state; combining the two to determine the fault characteristic value of each line section between each node of each phase; and determining the fault line section and fault phase where the interphase short-circuit fault occurs accordingly. This scheme can monitor the interphase high-resistance 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 find faults, determine fault points, shorten maintenance time, prevent fault expansion, ensure the safety of power supply operation in the substation area, and improve 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 low-voltage phase-to-phase high-resistance faults in distribution network areas. Background Art

[0002] Phase-to-phase short circuit fault is one of the common electrical faults in the distribution area. After the phase-to-phase high-resistance fault occurs, the circuit breaker is difficult to trip due to the small fault current, and the fault persists, causing low voltage and affecting normal power consumption; the high temperature at the fault point brings serious fire hazards; in short, the phase-to-phase high-resistance fault seriously threatens the normal power supply and personnel and equipment safety of the distribution area. The distribution area lines may use cables, overhead lines, etc., and the faults are difficult to troubleshoot. Identifying and accurately locating the phase-to-phase high-resistance faults in the distribution area is of great significance to improving the reliability and safety of the power system.

[0003] Fault identification and location are the primary and necessary steps in distribution network fault handling. There are many methods, such as locating the fault interval by constructing an improved matrix 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 reliable and accurate positioning method that can identify phase-to-phase high-resistance faults. Summary of the invention

[0004] Based on this, it is necessary to propose a method, device, equipment and medium for locating low-voltage phase-to-phase high-resistance faults in distribution station areas to address the above problems.

[0005] To achieve the above objectives, the present application provides, in a first aspect, a method for locating a low-voltage phase-to-phase high-resistance fault in a distribution station area, the method comprising:

[0006] 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 the other nodes is the first household meter voltage under the node, and the node 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 impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0008] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault;

[0009] Obtaining node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0010] Determine the impedance value of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0011] Determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state;

[0012] According to the fault characteristic values ​​of each line section between each node of each phase, the fault line section and the fault phase where the interphase short circuit fault occurs are determined.

[0013] In some embodiments, the impedance value of each line section between each node is based on Determine, where Z Lx is the 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, real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault includes:

[0015] The current of each phase at the outlet of the distribution transformer is monitored in real time. If the current sudden increase of any two phases exceeds the phase-to-phase fault current mutation threshold, it is determined that a phase-to-phase short circuit fault occurs in the distribution substation line.

[0016] In some embodiments, determining the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state specifically includes:

[0017] The absolute value of the difference between the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state is determined as the fault characteristic value of each line section between each node of each phase.

[0018] In some implementations, determining the faulty line section and the faulty phase where the interphase short circuit fault occurs according to the fault characteristic values ​​of each line section between each node of each phase includes:

[0019] Sort the line sections between the nodes of each phase from the load side to the power supply side, and determine the first line section whose fault characteristic value exceeds the fault characteristic threshold as the fault line section of the phase;

[0020] If only two of the phases have the fault line section, and the fault line sections of the two phases overlap, then it is determined that the interphase short circuit fault in the distribution station area is a two-phase short circuit fault, the fault point is located in the overlapping fault line section, and the two phases are fault phases;

[0021] If the fault line sections exist in all three phases and the fault line sections of the three phases overlap, it is determined that the phase-to-phase short circuit fault in the distribution station area is a three-phase short circuit fault, the fault point is located in the overlapping fault line sections, and the three phases are all fault phases.

[0022] In some implementations, the phase-to-phase fault current mutation threshold is 5% to 50% of the rated current on the low-voltage side of the distribution transformer.

[0023] In some embodiments, the fault characteristic threshold is k times the absolute value of the difference between the impedance value of the line section when the load power factor is 1 and the impedance value of the line section when the load power factor is 0.85 under the rated output current of the distribution transformer, where k is the sensitivity coefficient and the value of k is 1 to 2.

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

[0025] A first acquisition unit is used to acquire the node voltage and node 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 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 the other nodes is the first household meter voltage under the node, and the node 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 first impedance value determination unit, configured to determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0027] A monitoring unit, used to monitor the current of each phase at the outlet of the distribution transformer in real time to determine the phase-to-phase short circuit fault;

[0028] A second acquisition unit is used to acquire the node voltage and node current of each node of each phase under the inter-phase short circuit fault state;

[0029] A second impedance value determination unit, configured to determine the impedance values ​​of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0030] A fault characteristic value determination unit, configured to determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state;

[0031] The fault point determination unit is used to determine the fault line section and the fault phase where the interphase short circuit fault occurs according to the fault characteristic values ​​of each line section between each node of each phase.

[0032] 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:

[0033] 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 the other nodes is the first household meter voltage under the node, and the node 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;

[0034] Determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0035] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault;

[0036] Obtaining node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0037] Determine the impedance value of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0038] Determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state;

[0039] According to the fault characteristic values ​​of each line section between each node of each phase, the fault line section and the fault phase where the interphase short circuit fault occurs are determined.

[0040] 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:

[0041] 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 the other nodes is the first household meter voltage under the node, and the node 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;

[0042] Determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0043] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault;

[0044] Obtaining node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0045] Determine the impedance value of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0046] Determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state;

[0047] According to the fault characteristic values ​​of each line section between each node of each phase, the fault line section and the fault phase where the interphase short circuit fault occurs are determined.

[0048] The embodiments of the present invention have the following beneficial effects:

[0049] At present, when the distribution network is developing rapidly, the present invention is suitable for the comprehensive coverage of most distribution stations by smart meters, monitoring the current of each phase at the outlet of the distribution transformer, and determining the phase-to-phase short-circuit fault; obtaining the node voltage and node current of each node of each phase under normal state and phase-to-phase short-circuit fault state respectively; determining the impedance value of each line section between each node of each phase under normal state and the impedance value of each line section between each node of each phase under fault state; combining the two to determine the fault characteristic value of each line section between each node of each phase; determining the fault line section and the fault phase where the phase-to-phase short-circuit fault occurs accordingly, being able to monitor the phase-to-phase fault situation of 0.4kV low-voltage line in real time and locate it, being able to quickly locate the fault point, supporting the power grid operation and maintenance personnel to quickly discover hidden faults and determine the fault point, shortening the maintenance time and power outage time, and improving the power supply reliability, being a simple, reliable, highly accurate and low-cost new fault location method. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] 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.

[0051] in:

[0052] Figure 1 A schematic diagram of a flow chart of a method for locating a low-voltage phase-to-phase high-resistance fault in a distribution station area in an embodiment;

[0053] Figure 2 A distribution network simulation model diagram of a method for locating interphase high-resistance faults in a distribution station area in an embodiment;

[0054] Figure 3 It is a structural diagram of a low-voltage phase-to-phase high-resistance fault locating device in a distribution station area in one embodiment;

[0055] Figure 4 is a schematic diagram of the structure of a computer device in one embodiment;

[0056] Figure 5 Schematic diagram of the structure of a computer-readable storage medium in one embodiment. DETAILED DESCRIPTION

[0057] 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.

[0058] In the embodiment of the present application, a sensor data anomaly detection method is provided, see Figure 1 , Figure 1 The figure is a flow chart of locating a low-voltage phase-to-phase high-resistance fault in a distribution station area in an embodiment. The locating a low-voltage phase-to-phase high-resistance fault in a distribution station area includes steps S1 to S7.

[0059] Step S1, obtaining the node voltage and node 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 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 the other nodes is the first household meter voltage under the node, and the node 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;

[0060] Specifically, under normal operating conditions, the measurement terminal measures the voltage and current of each HPLC household meter, and records the voltage value measured by the HPLC household meter at each node as the node voltage of the node; the node voltage of the head node is measured by the measurement terminal, and the node current of each node except the head node is the algebraic sum of the HPLC household meter currents of the node and all nodes on the load side after the node.

[0061] For example, in Figure 2 In the simulation model shown, the currents at each node are: I 1 ~I 4 They are the household meter current values ​​uploaded by the HPLC household meters of nodes N1~N4 respectively.

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

[0063] In some embodiments, the impedance value of each line section between each node is based on Determine, where Z Lx is the 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 Nxis the node current of the node on the load side of the line section.

[0064] Step S3, real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault;

[0065] In some implementations, real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault includes:

[0066] The current of each phase at the outlet of the distribution transformer is monitored in real time. If the current sudden increase of any two phases exceeds the phase-to-phase fault current mutation threshold, it is determined that a phase-to-phase short circuit fault occurs in the distribution substation line.

[0067] In some implementations, the phase-to-phase fault current mutation threshold is 5% to 50% of the rated current on the low-voltage side of the distribution transformer.

[0068] Step S4, obtaining the node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0069] The specific acquisition method is the same as step S1.

[0070] Step S5, determining the impedance value of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0071] Step S6, determining the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state;

[0072] In some embodiments, the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase short circuit fault state, determine the fault characteristic value of each line section between each node of each phase, specifically including:

[0073] The absolute value of the difference between the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state is determined as the fault characteristic value of each line section between each node of each phase.

[0074] Step S7, determining the faulty line section and the faulty phase where the interphase short circuit fault occurs according to the fault characteristic values ​​of each line section between each node of each phase.

[0075] In some implementations, determining the faulty line section and the faulty phase where the interphase short circuit fault occurs according to the fault characteristic values ​​of each line section between each node of each phase includes:

[0076] Sort the line sections between the nodes of each phase from the load side to the power supply side, and determine the first line section whose fault characteristic value exceeds the fault characteristic threshold as the fault line section of the phase;

[0077] If only two of the phases have the fault line section, and the fault line sections of the two phases overlap, then it is determined that the interphase short circuit fault in the distribution station area is a two-phase short circuit fault, the fault point is located in the overlapping fault line section, and the two phases are fault phases;

[0078] If the fault line sections exist in all three phases and the fault line sections of the three phases overlap, it is determined that the phase-to-phase short circuit fault in the distribution station area is a three-phase short circuit fault, the fault point is located in the overlapping fault line sections, and the three phases are all fault phases.

[0079] In some embodiments, the fault characteristic threshold is k times the absolute value of the difference between the impedance value of the line section when the load power factor is 1 and the impedance value of the line section when the load power factor is 0.85 under the rated output current of the distribution transformer, where k is the sensitivity coefficient and the value of k is 1 to 2.

[0080] The present invention proposes a method for locating low-voltage phase-to-phase high-resistance faults in distribution stations. With the rapid development of distribution networks, as smart meters have covered most distribution stations in a relatively comprehensive manner, the present invention proposes to use smart meters in distribution stations to obtain node voltages and node currents of nodes in each phase under normal conditions and under phase-to-phase short-circuit fault conditions; determine the impedance values ​​of each line section between nodes in each phase under normal conditions and the impedance values ​​of each line section between nodes in each phase under fault conditions; determine the fault characteristic values ​​of each line section between nodes in each phase by combining the two; and determine the fault line section and fault phase where the phase-to-phase short-circuit fault occurs. This method is a new fault locating method that is simpler, more reliable, more accurate, and less costly, and 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 fault points, supporting power grid operation and maintenance personnel to quickly discover hidden faults and determine fault points, shorten maintenance time and power outage time, and improve power supply reliability.

[0081] The following is a further verification and explanation of the method for locating low-voltage phase-to-phase high-resistance faults in the distribution station area of ​​the present application in combination with specific embodiments:

[0082] According to the structure of the distribution network, establish Figure 2The simulation model shown in the figure specifically 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, 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.

[0083] A positioning device 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.

[0084] Case 1:

[0085] Set the AB phase short circuit fault to occur in the middle of Line3 interval, the transition resistance is 3Ω, and the phase short circuit fault current mutation threshold is set to 10% of the distribution transformer rated current, that is, 72.1A. According to the distribution station area low-voltage phase-to-phase high-resistance fault location method of this application, the fault location process includes:

[0086] Determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0087] The positioning device measures the effective value of voltage and current at N0, and requests the effective value of voltage and current of phase A of the user's electric meter set at N1 to N5 (the three phases are the same, taking phase A as an example), see Table 1,

[0088] Table 1: Node voltage, node current, and node current of each node of each phase under normal operating conditions

[0089]

[0090] The impedance values ​​of each line section between each node of each phase under normal conditions are calculated, see Table 2;

[0091] Table 2 Impedance values ​​of each line section between each node of each phase under normal conditions

[0092] Line section Impedance modulus (Ω) Line1 0.036 Line2 0.036 Line3 0.036 Line4 0.036 Line5 0.036

[0093] The positioning device monitors the current of each phase. After a phase-to-phase short circuit fault occurs in Line 3, the current of phases A and B suddenly changes from 56.3A to 153A and 176A, with sudden increases of 96.7A and 119.7A respectively, both exceeding the sudden change threshold of 72.1A (10% of the rated current of the distribution transformer). The current of phase C remains at 56.6A without obvious changes. It is judged that a phase-to-phase short circuit fault occurs in the line, and the fault phases are phases A and B that exceed the fault current sudden change threshold.

[0094] After the fault occurs, since the fault current is small, the positioning device requests data from each smart meter under the phase-to-phase short circuit fault state, and calculates the impedance value of each line section of each phase under the fault state.

[0095] The positioning device measures the effective value of voltage and current at N0, and requests the effective value of voltage and current of the user's electric meter set at N1 to N5, as shown in the following table:

[0096] Determine the impedance value of each line section between each node of each phase in the interphase short circuit fault state according to the node voltage and node current of each node of each phase in the interphase short circuit fault state of the distribution station area;

[0097] The positioning device measures the effective value of voltage and current at N0, and requests the effective value of voltage and current of the user meter set at N1 to N5, see Table 3:

[0098] Table 3 Node voltage and node current of each node of each phase under interphase short circuit fault condition

[0099]

[0100] The impedance values ​​of each line section between each node of each phase under the phase-to-phase short circuit fault state of each line section Line1-Line5 are calculated, referred to as the fault impedance value for short, and then combined with the impedance values ​​of each line section between each node of each phase under the normal state mentioned above, referred to as the normal impedance value for short, to determine the fault characteristic value, see Table 4 for details.

[0101] Table 4: Normal impedance value, fault impedance value, and fault characteristic value for each phase and line section

[0102]

[0103] Since the Line 3 line section of phases A and B is the first line section of the phase whose fault characteristic value exceeds the fault impedance threshold of the line section, the fault line section is the fault line section, and the fault characteristic values ​​of each line section of phase C do not exceed the fault impedance threshold of their respective line sections. There are only two phases with faulty line sections, and the faulty line sections overlap. It is determined that a two-phase short circuit fault occurs in the line section Line 3, and phases A and B are the faulty phases.

[0104] Case 2:

[0105] A three-phase interphase short circuit fault is set to occur in the middle of Line 3, with a transition resistance of 3Ω, and the interphase short circuit fault current mutation threshold is set to 10% of the rated current of the distribution transformer, that is, 72.1A. According to the above positioning method, the fault positioning process includes:

[0106] Determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0107] The positioning device measures the effective value of voltage and current at N0, and requests the effective value of voltage and current of phase A of the user meter set at N1 to N5 (the three phases are the same, taking phase A as an example), see Table 5,

[0108] Table 5: Node voltage, node current, and node current of each node of each phase under normal operating conditions

[0109]

[0110] The impedance values ​​of each line section between each node of each phase under normal conditions are calculated, see Table 6;

[0111] Table 6: Impedance values ​​of each line section between each node of each phase under normal conditions

[0112]

[0113]

[0114] The positioning device monitors the current of each phase. After a phase-to-phase short circuit fault occurs in Line 3, the currents of phases A, B, and C suddenly change from 56.3A to 252A, 253A, and 253A, with sudden increases of 195.7A, 196.7A, and 196.7A, respectively, all exceeding the sudden increase threshold of 72.1A (10% of the rated current of the distribution transformer).

[0115] After the fault occurs, since the fault current is small, the positioning device requests data from each smart meter under the phase-to-phase short circuit fault state, and calculates the impedance value of each line section of each phase under the fault state.

[0116] The positioning device measures the effective value of voltage and current at N0, and requests the effective value of voltage and current of the user's electric meter set at N1 to N5, as shown in the following table:

[0117] Determine the impedance value of each line section between each node of each phase in the interphase short circuit fault state according to the node voltage and node current of each node of each phase in the interphase short circuit fault state of the distribution station area;

[0118] The positioning device measures the effective value of voltage and current at N0, and requests the effective value of voltage and current of the user's electric meter set at N1 to N5, see Table 7;

[0119] Table 7: Node voltage and node current of each node of each phase under phase-to-phase short circuit fault state

[0120]

[0121]

[0122] The impedance values ​​of each line section between each node of each phase under the phase-to-phase short circuit fault state of each line section Line1-Line5 are calculated, referred to as the fault impedance value for short, and then combined with the impedance values ​​of each line section between each node of each phase under the normal state mentioned above, referred to as the normal impedance value for short, to determine the fault characteristic value, see Table 8 for details.

[0123] Table 8: Normal impedance value, fault impedance value, and fault characteristic value for each phase and line section

[0124]

[0125]

[0126] Since the Line 3 line section of phases A, B, and C is the first line section of the phase whose fault characteristic value exceeds the fault impedance threshold of the line section, it is the fault line section, and there are fault line sections in all three phases, and the fault line sections of the three phases coincide, it is determined that a three-phase short circuit fault occurs in the line section Line 3.

[0127] It can be seen that the simulation results of the above two cases are consistent with the determination results of this application. The low-voltage phase-to-phase high-resistance fault location method provided by this application can identify phase-to-phase high-resistance faults, which is a reliable and highly accurate location method.

[0128] In the embodiment of the present application, a low-voltage phase-to-phase high-resistance fault locating device is provided in a distribution station area. Figure 2 , Figure 2 A structural diagram of a low-voltage phase-to-phase high-resistance fault locating device in a distribution station area in one embodiment, the low-voltage phase-to-phase high-resistance fault locating device in a distribution station area includes: a first acquisition unit 201, a first impedance value determination unit 202, a monitoring unit 203, a second acquisition unit 204, a second impedance value determination unit 205, a fault characteristic value determination unit 206 and a fault point determination unit 207.

[0129] Wherein, the first acquisition unit 201 is used to obtain the node voltage and node current of each node of each phase in the normal operating state of the distribution station area, wherein the 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 the other nodes is the first household meter voltage under the node, and the node 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;

[0130] The first impedance value determination unit 202 is used to determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0131] A monitoring unit 203 is used to monitor the current of each phase at the outlet of the distribution transformer in real time to determine the phase-to-phase short circuit fault;

[0132] The second acquisition unit 204 is used to acquire the node voltage and node current of each node of each phase under the inter-phase short circuit fault state;

[0133] The second impedance value determination unit 205 is used to determine the impedance value of each line section between each node of each phase in the interphase short circuit fault state according to the node voltage and node current of each node of each phase in the interphase short circuit fault state;

[0134] A fault characteristic value determination unit 206, configured to determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state;

[0135] The fault point determination unit 207 is used to determine the fault line section and the fault phase where the interphase short circuit fault occurs according to the fault characteristic values ​​of each line section between each node of each phase.

[0136] In some embodiments, the first impedance value determining unit 202 and the second impedance value determining unit 205 are further configured to Determine the impedance value of each line section between each node, where Z Lx is the 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.

[0137] In some embodiments, the monitoring unit 203 is further configured to monitor the current of each phase at the outlet of the distribution transformer in real time. If the current sudden increase of any two phases exceeds the phase-to-phase fault current mutation threshold, it is determined that a phase-to-phase short circuit fault occurs in the distribution station area line.

[0138] In some embodiments, the fault characteristic value determination unit 206 is further configured to determine the absolute value of the difference between the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state as the fault characteristic value of each line section between each node of each phase.

[0139] In some embodiments, the fault point determination unit 207 is further configured to sort the line sections between the nodes of each phase from the load side to the power supply side, and determine the first line section whose fault characteristic value exceeds the fault characteristic threshold as the fault line section of the phase;

[0140] If only two of the phases have the fault line section, and the fault line sections of the two phases overlap, then it is determined that the interphase short circuit fault in the distribution station area is a two-phase short circuit fault, the fault point is located in the overlapping fault line section, and the two phases are fault phases;

[0141] If the fault line sections exist in all three phases and the fault line sections of the three phases overlap, it is determined that the phase-to-phase short circuit fault in the distribution station area is a three-phase short circuit fault, the fault point is located in the overlapping fault line sections, and the three phases are all fault phases.

[0142] In some embodiments, the distribution station area low-voltage phase-to-phase high-resistance fault locating device also includes a phase-to-phase fault current mutation threshold determination unit 208, and the phase-to-phase fault current mutation threshold determination unit 208 is also configured to determine the phase-to-phase fault current mutation threshold to 5% to 50% of the rated current of the low-voltage side of the distribution transformer.

[0143] In some embodiments, the distribution station area low-voltage phase-to-phase high-resistance fault locating device also includes a fault characteristic threshold 209, and the fault characteristic threshold 209 is also configured to determine the fault characteristic threshold as k times the absolute value of the difference between the impedance value of the line section when the load power factor is 1 under the rated output current of the distribution transformer and the impedance value of the line section when the load power factor is 0.85, where k is the sensitivity coefficient and the value of k is 1 to 2.

[0144] For other details about how the modules in the low-voltage phase-to-phase high-resistance fault locating device in the distribution station area implement the above-mentioned technical solution, please refer to the description of the low-voltage phase-to-phase high-resistance fault locating method in the distribution station area provided above, which will not be repeated here.

[0145] In an embodiment of the present application, a computer device is provided. Figure 3 , Figure 3 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:

[0146] 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 the other nodes is the first household meter voltage under the node, and the node 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;

[0147] Determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0148] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault;

[0149] Obtaining node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0150] Determine the impedance value of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0151] Determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state;

[0152] According to the fault characteristic values ​​of each line section between each node of each phase, the fault line section and the fault phase where the interphase short circuit fault occurs are determined.

[0153] 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.

[0154] In an embodiment of the present application, a computer readable storage medium is provided. Figure 4 , Figure 4 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:

[0155] 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 the other nodes is the first household meter voltage under the node, and the node 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;

[0156] Determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area;

[0157] Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault;

[0158] Obtaining node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0159] Determine the impedance value of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state;

[0160] Determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state;

[0161] According to the fault characteristic values ​​of each line section between each node of each phase, the fault line section and the fault phase where the interphase short circuit fault occurs are determined.

[0162] 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.

[0163] 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).

[0164] The technical features of the above embodiments may be combined arbitrarily. 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.

[0165] 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 low-voltage phase-to-phase high-resistance faults in a distribution station area, 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 the other nodes is the first household meter voltage under the node, and the node 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; Determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area; Real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault; Obtaining node voltage and node current of each node of each phase under the interphase short circuit fault state; Determine the impedance value of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state; Determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state; According to the fault characteristic values ​​of each line section between each node of each phase, the fault line section and the fault phase where the interphase short circuit fault occurs are determined.

2. The method for locating low-voltage phase-to-phase high-resistance faults in a distribution station area according to claim 1 is characterized in that: The impedance value of each line section between the nodes is based on Determine, where Z Lx is the 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 method for locating low-voltage phase-to-phase high-resistance faults in a distribution station area according to claim 2 is characterized in that: The real-time monitoring of the current of each phase at the outlet of the distribution transformer to determine the phase-to-phase short circuit fault includes: The current of each phase at the outlet of the distribution transformer is monitored in real time. If the current sudden increase of any two phases exceeds the phase-to-phase fault current mutation threshold, it is determined that a phase-to-phase short circuit fault occurs in the distribution substation line.

4. The method for locating low-voltage phase-to-phase high-resistance faults in a distribution station area according to claim 3 is characterized in that: Determining the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state, specifically including: The absolute value of the difference between the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state is determined as the fault characteristic value of each line section between each node of each phase.

5. The method for locating low-voltage phase-to-phase high-resistance faults in a distribution station area according to claim 4 is characterized in that: The determining, according to the fault characteristic values ​​of each line section between each node of each phase, the fault line section and the fault phase where the interphase short circuit fault occurs comprises: Sort the line sections between the nodes of each phase from the load side to the power supply side, and determine the first line section whose fault characteristic value exceeds the fault characteristic threshold as the fault line section of the phase; If only two of the phases have the fault line section, and the fault line sections of the two phases overlap, then it is determined that the interphase short circuit fault in the distribution station area is a two-phase short circuit fault, the fault point is located in the overlapping fault line section, and the two phases are fault phases; If the fault line sections exist in all three phases and the fault line sections of the three phases overlap, it is determined that the phase-to-phase short circuit fault in the distribution station area is a three-phase short circuit fault, the fault point is located in the overlapping fault line sections, and the three phases are all fault phases.

6. The method for locating low-voltage phase-to-phase high-resistance faults in a distribution station area according to claim 5 is characterized in that: The phase-to-phase fault current mutation threshold is 5% to 50% of the rated current on the low-voltage side of the distribution transformer.

7. The method for locating low-voltage phase-to-phase high-resistance faults in a distribution station area according to claim 6 is characterized in that: The fault characteristic threshold is k times the absolute value of the difference between the impedance value of the line section when the load power factor is 1 and the impedance value of the line section when the load power factor is 0.85 under the rated output current of the distribution transformer, where k is the sensitivity coefficient and the value of k is 1 to 2.

8. A low-voltage phase-to-phase high-resistance fault location device in a distribution station area, 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 operating state of the distribution station area, wherein the nodes include 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 the other nodes is the first household meter voltage under the node, and the node 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 first impedance value determination unit, configured to determine the impedance value of each line section between each node of each phase in a normal state according to the node voltage and node current of each node of each phase in a normal operating state of the distribution station area; A monitoring unit, used to monitor the current of each phase at the outlet of the distribution transformer in real time to determine the phase-to-phase short circuit fault; A second acquisition unit is used to acquire the node voltage and node current of each node of each phase under the inter-phase short circuit fault state; A second impedance value determination unit, configured to determine the impedance values ​​of each line section between each node of each phase under the interphase short circuit fault state according to the node voltage and node current of each node of each phase under the interphase short circuit fault state; A fault characteristic value determination unit, configured to determine the fault characteristic value of each line section between each node of each phase according to the impedance value of each line section between each node of each phase in the normal state and the impedance value of each line section between each node of each phase in the phase-to-phase short circuit fault state; The fault point determination unit is used to determine the fault line section and the fault phase where the interphase short circuit fault occurs according to the fault characteristic values ​​of each line section between each node of each phase.

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 7.

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 7.

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