A distribution line fault location method, system and storage medium

Abstract

The embodiment of the present invention discloses a method, system and storage medium for locating faults in a distribution line. The method includes: obtaining the line impedance value of each line section and the current value of the distribution network under normal operation; determining the type of interphase fault according to the current value; obtaining the power parameter data of each node of the distribution network under the fault state; determining the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data under any fault phase; determining the node fault voltage of each node according to the line impedance value, node user active power and node user reactive power of the line section where the current node is located; locating the fault line section according to the comparison of the node reference voltage and the node fault voltage. By using the power parameter data and accurately locating the fault according to the impedance characteristics of the line section, the grounding fault of the line can be monitored in real time and located.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution line fault handling, and in particular to a power distribution line fault locating method, system and storage medium. Background Art

[0002] Low-voltage grounding fault is one of the common electrical faults in the distribution area. Low-voltage grounding fault causes unbalanced operation of distribution transformers, heating and fire at the fault point, etc., threatening the normal power supply of the area and the safety of personnel and equipment. The line area may use cables, overhead lines, etc., and the fault is difficult to troubleshoot. Identifying and accurately locating low-voltage grounding 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. For example, Xu Biao et al., in their paper "Distribution Network Fault Location Combining Matrix Algorithm and Optimization Algorithm", constructed an improved matrix to locate the fault interval, and established an optimization model to make fault-tolerant judgments on fault location. The fault tolerance performance of this method is outstanding, but the accuracy of fault location is relatively insufficient. In their paper "Intelligent Distributed Fault Section Location Algorithm for Distribution Network Based on Bayesian Estimation", Zheng Chenling et al. further used the Bayesian probability model to determine the fault section through the newly established causal relationship model of feeder status and current overlimit. 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 low-voltage grounding faults in distribution sections, 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 distribution line fault location method, system and storage medium to address the above problems.

[0005] A method for locating a distribution line fault, the method comprising:

[0006] Obtain the line impedance value of each line section and the current value of the distribution network under normal operating conditions.

[0007] The type of the phase-to-phase fault is determined according to the current value.

[0008] Obtain the power parameter data of each node in the distribution network under fault conditions.

[0009] Under any fault phase, the node reference voltage, node user active power and node user reactive power of the current node are determined according to the power parameter data.

[0010] The node fault voltage of each node is determined according to the line impedance value of the line section where the current node is located, the node user active power and the node user reactive power.

[0011] The faulty line section is located according to the comparison between the node reference voltage and the node fault voltage.

[0012] Wherein, determining the type of phase-to-phase fault according to the voltage value and the current value specifically includes:

[0013] If each line section is in a medium-voltage distribution network, it is determined that the current values ​​of any two phases at the main transformer outlet are greater than the phase-to-phase short-circuit fault current mutation threshold, and the remaining phase is less than or equal to the phase-to-phase short-circuit fault current mutation threshold, then a bidirectional phase-to-phase short-circuit fault occurs; it is determined that the current values ​​of the three phases at the main transformer outlet are all greater than the phase-to-phase short-circuit fault current mutation threshold, then a three-phase phase-to-phase short-circuit fault occurs.

[0014] If each line section is in a low-voltage distribution network, it is determined that the current values ​​of any two phases at the distribution transformer outlet are greater than the phase-to-phase short-circuit fault current mutation threshold, and the remaining phase is less than or equal to the phase-to-phase short-circuit fault current mutation threshold, then a bidirectional phase-to-phase short-circuit fault occurs; it is determined that the current values ​​of the three phases at the distribution transformer outlet are all greater than the phase-to-phase short-circuit fault current mutation threshold, then a three-phase phase-to-phase short-circuit fault occurs.

[0015] The obtaining of power parameter data of each node in the distribution network under a fault state specifically includes:

[0016] In the fault state, it is determined that the low-voltage distribution network is in operation, and the voltage data, active power data, and reactive power data of the user end of each node in the interval are obtained.

[0017] In the fault state, it is determined that the medium voltage distribution network is in operation, and the three-phase low voltage side voltage data and the three-phase low voltage side current data of the low voltage side of each node distribution transformer are obtained.

[0018] Wherein, under any fault phase, determining the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data specifically includes:

[0019] Under any fault phase, the node reference voltage of the current node is determined according to the voltage data of the user end of the current node in the interval.

[0020] The node user active power of the current node is determined according to the algebraic sum of the active power data of the current node user end in the interval.

[0021] The node user reactive power of the current node is determined according to the algebraic sum of the reactive power data of the current node user end in the interval.

[0022] Wherein, under any fault phase, determining the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data specifically includes:

[0023] Under any fault phase, the low-voltage side positive sequence current and the low-voltage side negative sequence current of the current fault phase current are determined according to the three-phase low-voltage side current data of the current node.

[0024] The high-voltage side positive-sequence current and the high-voltage side negative-sequence current are determined according to the low-voltage side positive-sequence current and the low-voltage side negative-sequence current.

[0025] The three-phase high-voltage side current of the current node is determined according to the high-voltage side positive-sequence current and the high-voltage side negative-sequence current.

[0026] The low-voltage side positive-sequence voltage and the low-voltage side negative-sequence voltage of the current fault phase voltage are determined according to the three-phase low-voltage side voltage data of the current node and the low-voltage side positive-sequence current and the low-voltage side negative-sequence current.

[0027] The high-voltage side positive-sequence voltage and the high-voltage side negative-sequence voltage are determined according to the low-voltage side positive-sequence voltage and the low-voltage side negative-sequence voltage.

[0028] The three-phase high-voltage side voltage of the current node is determined according to the high-voltage side positive-sequence voltage and the high-voltage side negative-sequence voltage.

[0029] A node reference voltage of a current node is determined according to the voltage amplitude of the three-phase high-voltage side voltage.

[0030] The node user active power and the node user reactive power of the current node are determined according to the product of the three-phase high-voltage side current and the three-phase high-voltage side voltage.

[0031] The determining of the node fault voltage of each node according to the line impedance value, the node user active power and the node user reactive power of the line section where the current node is located specifically includes:

[0032] From the end node on the load side of the line section to the starting node on the power supply side of the line section, the node active power and node reactive power of each node are determined in turn according to the line impedance value of the line section where the current node is located, the node reference voltage of the node on the load side of the current line section, the node user active power and the node user reactive power.

[0033] From the end node on the load side of the line section to the starting node on the power supply side of the line section, the node fault voltage of each node is determined in turn according to the node reactive power, node active power of the adjacent nodes on the load side of the current node and the line impedance value of the load side line section where the current node is located.

[0034] Among them, the node active power and node reactive power of each node are determined in sequence from the end node on the load side of the line section to the starting node on the power supply side of the line section according to the line impedance value of the line section where the current node is located, the node voltage of the node on the load side of the current line section, the node user active power and the node user reactive power, specifically including:

[0035] The node active power and the node reactive power of the end node are determined according to the node user active power and the node user reactive power of the end node on the line load side.

[0036] According to the line impedance value of the load side line section where the non-end node on the line load side is located, the node reference voltage of the load side node, the node user active power and the node user reactive power, the node active power and the node reactive power of the non-end node are determined in turn.

[0037] The step of determining the node active power and the node reactive power of the non-end node in sequence according to the line impedance value of the load side line section where the non-end node on the load side of the line is located, the node reference voltage of the load side node, the node user active power and the node user reactive power specifically includes:

[0038] The apparent power lost in the line section is determined based on the line impedance value of the load-side line section where the non-terminal node on the load side of the line is located, the node reference voltage of the load-side node, the node active power and the node reactive power.

[0039] The active power of the line section loss and the reactive power of the line section loss are determined according to the apparent power of the line section loss.

[0040] The node active power of the current node is determined based on the algebraic sum of the node user active power of the current node, the active power lost in the load-side line section where the current node is located, and the node active power of the nodes adjacent to the load side of the current node.

[0041] The node reactive power of the current node is determined based on the algebraic sum of the node user reactive power of the current node, the reactive power lost in the load-side line section where the current node is located, and the node reactive power of the nodes adjacent to the load side of the current node.

[0042] The determining of the apparent power lost in the line section according to the line impedance value of the load side line section where the non-terminal node on the load side of the line is located, the voltage data of the load side node, the node active power and the node reactive power specifically includes:

[0043] according to Determine the apparent power lost in the line section, where S L is the apparent power loss in the line section; P NL is the node active power of the load side node in the line section; Q NL is the node reactive power of the load side node in the line section; U T-NL is the node reference voltage of the load side node of the line section; Z Lis the line impedance value of the line section.

[0044] Among them, the node fault voltage of each node is determined in sequence from the end node on the load side of the line section to the starting node on the power supply side of the line section according to the node reactive power, node active power of the adjacent node on the load side of the current node and the line impedance value of the load side line section where the current node is located, specifically including:

[0045] The node fault voltage of the end node is determined according to the node reference voltage of the end node on the load side of the line section.

[0046] The node fault voltage of the non-terminal node is determined according to the line impedance value of the load-side line section where the non-terminal node on the load side of the line section is located, and the node active power and node reactive power of the node adjacent to the load side of the current non-terminal node.

[0047] The step of determining the node fault voltage of the non-terminal node according to the line impedance value of the load-side line section where the non-terminal node on the load side of the line section is located, and the node active power and node reactive power of the node adjacent to the load side of the current non-terminal node specifically includes:

[0048] according to Determine the node fault voltage of the non-terminal node, where U g_Nx is the node fault voltage of the node; U J_Nnx is the node fault voltage of the adjacent node on the load side of the node; P Nnx is the node active power of the adjacent node on the load side of the node; Q Nnx is the node reactive power of the adjacent nodes on the load side of the node; R Lnext is the real part of the line impedance of the line section on the load side of the node; X Lnext It is the imaginary part of the line impedance of the line section on the load side of the node.

[0049] The step of locating the faulty line section according to the comparison between the node reference voltage and the node fault voltage specifically includes:

[0050] The comparison between the node reference voltage and the node fault voltage of each node is determined in sequence from the load side to the power supply side.

[0051] If the first node fault voltage is less than the node reference voltage and the node fault voltage is greater than the fault characteristic threshold, the load side line section where the node corresponding to the node fault voltage is located is the fault line section.

[0052] If the first node fault voltage is greater than or equal to the node reference voltage, and the node fault voltage is less than or equal to the fault characteristic threshold, then the load side line section where the node corresponding to the node fault voltage is located is a non-fault line section.

[0053] A distribution line fault location system, the system comprising:

[0054] The first acquisition module is used to obtain the line impedance value of each line section and the voltage value and current value of the distribution network under normal operating conditions.

[0055] The phase-to-phase fault determination module is used to determine the phase-to-phase fault type according to the voltage value and the current value.

[0056] The second acquisition module is used to obtain the power parameter data of each node in the distribution network under a fault state.

[0057] The node user active power and node user reactive power determination module is used to determine the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data under any fault phase.

[0058] The node fault voltage determination module is used to determine the node fault voltage of each node according to the line impedance value, the node user active power and the node user reactive power of the line section where the current node is located.

[0059] The fault line section determination module is used to locate the fault line section according to the comparison between the node reference voltage and the node fault voltage.

[0060] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor executes the steps of the method described above.

[0061] The embodiments of the present invention have the following beneficial effects:

[0062] This application utilizes the power parameter data of the normal operating state and the fault state of the distribution section, and accurately locates the fault according to the impedance characteristics of the line section, which reduces the positioning cost and has a high accuracy rate. It can monitor the grounding fault of the line in real time and locate it, quickly locate the fault point, support the power grid operation and maintenance personnel to quickly discover the fault, determine the fault point, shorten the maintenance time, prevent the fault from expanding, ensure the safety of the power supply operation in the section, and improve the reliability of power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] 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.

[0064] in:

[0065] Figure 1 A schematic diagram of a flow chart of an embodiment of a method for locating a fault in a power distribution line provided by the present invention;

[0066] Figure 2 A schematic diagram of a flow chart of another embodiment of a method for locating a power distribution line fault provided by the present invention;

[0067] Figure 3 It is a schematic diagram of a distribution network simulation calculation model provided by the present invention;

[0068] Figure 4 A schematic diagram of a flow chart of another embodiment of a method for locating a power distribution line fault provided by the present invention;

[0069] Figure 5 is another schematic diagram of the distribution network simulation calculation model provided by the present invention;

[0070] Figure 6 A schematic diagram of the structure of an embodiment of a distribution line fault location system provided by the present invention;

[0071] Figure 7 A schematic structural diagram of an embodiment of a storage medium provided by the present invention. DETAILED DESCRIPTION

[0072] 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.

[0073] like Figure 1 As shown, Figure 1 A schematic diagram of a flow chart of an embodiment of a method for locating a power distribution line fault provided by the present invention. A method for locating a power distribution line fault, the method comprising:

[0074] S101: Obtain the line impedance value of each line section and the current value of the distribution network under normal operating conditions.

[0075] For example, the line section is in a low-voltage distribution network. When the power system is in normal operation, each line section in the power system is measured to determine the line impedance value of each line section. The two ends of the line section are user nodes, each node is connected to the user's smart meter, and the smart meter measures the power usage. At the same time, the positioning equipment is used to measure the voltage and current values ​​at the distribution transformer outlet.

[0076] For example, the line section is in a medium voltage distribution network. When the power system is in normal operation, each line section in the power system is measured to determine the line impedance value of each line section. The two ends of the line section are nodes, and the low voltage side of the distribution transformer of each node is connected to a measurement terminal. At the same time, a positioning device is used to measure the voltage and current values ​​at the main transformer outlet.

[0077] S102: Determine the type of phase-to-phase fault according to the current value.

[0078] Exemplarily, the line section is in a low-voltage distribution network. By analyzing the measured current value, it is determined whether a phase-to-phase fault has occurred in the power system and the type of the phase-to-phase fault is determined. Specifically, if the current values ​​of any two phases at the distribution transformer outlet are greater than the phase-to-phase short-circuit fault current mutation threshold, and the remaining phase is less than or equal to the phase-to-phase short-circuit fault current mutation threshold, a bidirectional phase-to-phase short-circuit fault occurs; if the current values ​​of the three phases at the distribution transformer outlet are all greater than the phase-to-phase short-circuit fault current mutation threshold, a three-phase phase-to-phase short-circuit fault occurs.

[0079] Exemplarily, the line section is in a medium-voltage distribution network, and the positioning equipment detects the current value of each phase at the main transformer outlet. If the current values ​​of any two phases at the main transformer outlet are greater than the phase-to-phase short-circuit fault current mutation threshold, and the remaining phase is less than or equal to the phase-to-phase short-circuit fault current mutation threshold, a bidirectional phase-to-phase short-circuit fault occurs; if the current values ​​of the three phases at the main transformer outlet are all greater than the phase-to-phase short-circuit fault current mutation threshold, a three-phase phase-to-phase short-circuit fault occurs.

[0080] S103: Obtain power parameter data of each node in the interval under fault status.

[0081] Exemplarily, in a fault state, it is determined that the network is in a low-voltage distribution network, and the positioning device requests the voltage data, active power data, and reactive power data provided by the smart meters at the user end of each node, which help to locate the fault more accurately.

[0082] Exemplarily, in a fault state, it is determined that the medium voltage distribution network is in place, and the positioning device requests the three-phase low-voltage side voltage data and the three-phase low-voltage side current data of the low-voltage side of each node distribution transformer.

[0083] S104: Under any fault phase, determine the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data.

[0084] Exemplarily, a fault phase is selected, and the node reference voltage of the current node is determined according to the three-phase low-voltage side voltage data of the current node user end; the algebraic sum of the low-voltage side active power data of the current node user end under the fault phase is used as the node user active power of the current node; the algebraic sum of the low-voltage side reactive power data of the current node user end under the fault phase is used as the node user reactive power of the current node. Furthermore, the node user active power and node user reactive power of the corresponding node under any fault are obtained.

[0085] Exemplarily, under any fault phase, the three-phase low-voltage side voltage data and the three-phase low-voltage side current data are used to reversely calculate the three-phase high-voltage side voltage as the node reference voltage of the node where the distribution transformer is located. After the three-phase high-voltage side voltage and the three-phase high-voltage side current are reversely calculated, the active power and reactive power are determined according to the product of the two as the node user active power and node user reactive power of the node. Among them, the product of the three-phase high-voltage side current and the three-phase high-voltage side voltage obtains the three-phase apparent power of the node, and its real part and imaginary part are the node user active power and node user reactive power of the node, respectively.

[0086] S105: Determine the node fault voltage of each node according to the line impedance value of the line section where the current node is located, the node user active power and the node user reactive power.

[0087] Exemplarily, the node active power of the end node is first determined according to the node user active power of the end node on the load side of the line section. The node reactive power of the end node is determined according to the node user reactive power of the end node on the load side of the line section. The apparent power lost in the line section is determined according to the line impedance value of the load side line section where the non-end node on the load side of the line is located, the node reference voltage of the load side node, the node active power and the node reactive power. The apparent power lost in the line section is shown in the following formula:

[0088]

[0089] Among them, S L is the apparent power loss in the line section; P NL is the node active power of the load side node in the line section; Q NL is the node reactive power of the load side node in the line section; U T-NL is the node reference voltage of the load side node of the line section; Z L is the line impedance value of the line section.

[0090] Furthermore, the active power of the line section loss and the reactive power of the line section loss are determined according to the apparent power of the line section loss. The active power of the line section loss is the real part of the apparent power of the line section loss; the reactive power of the line section loss is the imaginary part of the apparent power of the line section loss.

[0091] Furthermore, the node active power of the current node is determined based on the algebraic sum of the node user active power of the current node, the active power lost in the line section on the load side where the current node is located, and the node active power of the nodes adjacent to the load side of the current node; the node reactive power of the current node is determined based on the algebraic sum of the node user reactive power of the current node, the reactive power lost in the line section on the load side where the current node is located, and the node reactive power of the nodes adjacent to the load side of the current node.

[0092] Further, the node fault voltage is calculated one by one from the load side to the power supply side, and the node fault voltage of the line end node is equal to the node reference voltage. The node fault voltage of the end node is determined according to the node reference voltage of the end node on the load side of the line section. The node fault voltage of the non-end node is determined according to the line impedance value of the load side line section where the non-end node on the load side of the line section is located, the node active power and the node reactive power of the node adjacent to the load side of the current non-end node, and the node fault voltage of the non-end node is determined according to the following formula:

[0093]

[0094] Among them, U g_Nx is the node fault voltage of the node; U J_Nnx is the node fault voltage of the adjacent node on the load side of the node; P Nnx is the node active power of the adjacent node on the load side of the node; Q Nnx is the node reactive power of the adjacent nodes on the load side of the node; R Lnext is the real part of the line impedance of the line section on the load side of the node; X Lnext It is the imaginary part of the line impedance of the line section on the load side of the node.

[0095] S106: Locate the faulty line section based on the comparison between the node reference voltage and the node fault voltage.

[0096] Exemplarily, the comparison between the node reference voltage and the node fault voltage of each node is determined in turn from the load side to the power supply side; if the first node fault voltage is less than the node reference voltage, and the node fault voltage is greater than the fault characteristic threshold, then the load side line section where the node corresponding to the node fault voltage is located is the fault line section; if the first node fault voltage is greater than or equal to the node reference voltage, and the node fault voltage is less than or equal to the fault characteristic threshold, then the load side line section where the node corresponding to the node fault voltage is located is the non-fault line section.

[0097] From the above description, it can be seen that the present application utilizes the power parameter data of the distribution line section under normal operating conditions and fault conditions, and accurately locates the fault according to the impedance characteristics of the line section, thereby reducing the positioning cost and having a high accuracy rate. It is capable of real-time monitoring and locating the grounding fault of the line, quickly locating the fault point, and supporting power grid operation and maintenance personnel to quickly discover faults, determine the fault point, shorten maintenance time, prevent the fault from expanding, ensure the safety of power supply operation in the section, and improve power supply reliability.

[0098] like Figure 2 As shown, Figure 2 A schematic diagram of a flow chart of another embodiment of a method for locating a power distribution line fault provided by the present invention. A method for locating a power distribution line fault, the method comprising:

[0099] S201: Obtain the line impedance value of each line section and the voltage and current values ​​of the distribution network under normal operating conditions.

[0100] For example, in a low-voltage distribution network, according to the structure of the distribution network, a 0.4kV distribution system model is established using PSCAD simulation software, including 5 sections of 0.4kV lines and several 0.4kV loads. Figure 3 As shown, Figure 3It is a schematic diagram of the distribution network simulation calculation model provided by the present invention. 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 a 0.4kV low-voltage overhead conductor setting of JKLYJ-50. The impedance parameter of this model of 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, three models with different power factors, Load1~Load3, are set, and the power factors are 0.8, 0.9, and 0.95, respectively. An AB phase-to-phase short-circuit fault is set between N2-N3, and the transition resistance is set to 1Ω. The phase-to-phase short-circuit fault current mutation threshold is set to 10% of the rated current of the distribution transformer. The fault interval is located according to the distribution line fault location method. The line impedance values ​​of all line sections measured are 0.0336+j0.0146Ω, the line resistance is R=0.0336Ω, and the line reactance is X=0.0146Ω.

[0101] S202: Determine the type of interphase fault according to the voltage value and current value at the distribution transformer outlet.

[0102] For example, the positioning equipment monitors the current of each phase at the distribution transformer outlet. After a ground fault occurs in the N2-N3 line section, the current of phases A and B suddenly changes from 177A to 433A and 469A, with sudden increases of 256A and 292A respectively, both exceeding the sudden increase threshold of 72.1A (10% of the rated current of the distribution transformer), and the current of phase C has no obvious change. It is determined that a short circuit fault occurs between phases AB.

[0103] S203: Obtain power parameter data of each node in the interval under fault status.

[0104] Exemplarily, in a fault state, the voltage data, active power data and reactive power data of each smart meter at each node user end of the positioning device request interval are shown in Table 1, which is the A-phase power parameter data of each node user end:

[0105] Table 1 Phase A voltage and load power at each node

[0106]

[0107]

[0108] Among them, load 11 is Load 1 under node N1, load 12 is Load 2 under node N1, load 13 is Load 3 under node N1, and so on.

[0109] S204: Under any fault phase, determine the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data.

[0110] Exemplarily, a fault phase is selected to calculate the node reference voltage, node user active power, and node user reactive power of the corresponding node. Specifically, phase A is selected, the node reference voltage is the same as the voltage measured by the user-side smart meter in the above table, and the node reference voltage of the current node is determined according to the voltage data of the current node. The node user active power and node user reactive power are shown in Table 2, which shows the node user active power and node user reactive power of phase A of each node.

[0111] Table 2 Node user active power and node user reactive power of each node

[0112] node Node user active power (kW) Node user reactive power (kvar) N1 7.14 3.0 N2 6.91 2.236 N3 5.988 2.317 N4 6.412 2.098 N5 6.128 2.240

[0113] S205: From the end node on the load side of the line section to the starting node on the power supply side of the line section, determine the node active power and node reactive power of each node in turn according to the line impedance value of the line section where the current node is located, the node reference voltage of the node on the load side of the current line section, the node user active power and the node user reactive power.

[0114] Exemplarily, the node active power and node reactive power of each node are calculated one by one from the load side to the power supply side. For the load side terminal node N5, its node active power is equal to the node user active power of the node 6.128kW, and its node reactive power is equal to the node user reactive power of the node 2.24kvar.

[0115] When calculating the node active power and node reactive power of N4, the node (reactive) power of node N5 (the load side node of node N4) is first used to calculate the active (reactive) power loss of the N4-N5 section (the load side line section where the N4 node is located).

[0116] For node N4, the node active power is equal to the algebraic sum of the user active power of node N4 (6.412kW), the active power lost in the load-side line section N4-N5 where node N4 is located, and the node active power of node N5 (6.128kW) adjacent to the load side of node N4. The node reactive power is equal to the algebraic sum of the user reactive power of node N4 (2.098kvar), the reactive power lost in the load-side line section N4-N5 where node N4 is located, and the node reactive power of node N5 (2.24kvar) adjacent to the load side of node N4.

[0117] The apparent power loss in the line section N4-N5 is:

[0118]

[0119] The active power loss in the line section N4-N5 is 0.037kW, and the reactive power loss in the line section N4-N5 is 0.016kVA. Then the node active power of node N4 is: P N4 =6.412+0.037+6.128=12.577(kW) The node reactive power of node N4 is: Q N4 =2.24+0.016+2.098=4.354 (kvar). Similarly, the node active power and node reactive power of other nodes can be obtained. The power loss of each line section is shown in Table 3. Table 3 shows the power loss of each line section:

[0120] Table 3 Power loss in each line section

[0121] Line segment Active power loss (kW) Reactive power loss (kvar) N0-N1 0.905 0.394 N1-N2 0.591 0.257 N2-N3 0.329 0.143 N3-N4 0.151 0.066 N4-N5 0.037 0.016

[0122] The node active power and node reactive power of each node are shown in Table 4. Table 4 shows the node active power and node reactive power of each node:

[0123] Table 4 Node active power and node reactive power of each node

[0124] node Node active power (kW) Node reactive power (kvar) N1 33.695 12.376 N2 25.960 9.116 N3 18.717 6.737 N4 12.577 4.354 N5 6.128 2.240

[0125] S206: From the end node on the load side of the line section to the starting node on the power supply side of the line section, determine the node fault voltage of each node in turn according to the node reactive power, node active power of the adjacent nodes on the load side of the current node and the line impedance value of the load side line section where the current node is located.

[0126] Exemplarily, for the load-side terminal node N5 of the line section, its node fault voltage is equal to its node reference voltage 197.2V.

[0127] For node N4, its node fault voltage is calculated by the following formula:

[0128]

[0129] Among them, U g_N4 is the node fault voltage of node N4, U g_N5 is the node fault voltage of the load side adjacent node N5 of the node N4; N5 Q is the node active power of the load-side adjacent node N5 of node N4; N5 is the node reactive power of the load-side adjacent node N5 of node N4; R N4-N5 is the line resistance (real part of line impedance value) of the load side line section N4-N5 of the node N4; N4-N5 It is the line reactance (imaginary part of the line impedance value) of the line section N4-N5 on the load side of the node N4.

[0130] Similarly, the node fault voltages of N0-N3 are calculated. The node fault voltages of all nodes are shown in Table 5. Table 5 shows the node reference voltage, node fault voltage and amplitude of each node.

[0131] Table 5 Node reference voltage, node fault voltage and amplitude of each node

[0132] node Node reference voltage (V) Node fault voltage(V) Decrease(V) N0 231.6 224.7 6.9 N1 218.7 212.3 6.4 N2 207.5 204.5 3 N3 200.9 200.9 0 N4 198.4 198.4 0 N5 197.2 197.2 0

[0133] S207: Locate the faulty line section based on the comparison between the node reference voltage and the node fault voltage.

[0134] Exemplarily, from the load side to the power side, the node reference voltage and the node fault voltage of each node are compared respectively; the first node whose fault voltage is less than the node reference voltage and whose fault voltage is greater than the fault characteristic threshold is N2, and the load side line section corresponding to this node is N2-N3, and this section is determined to be the fault line section.

[0135] like Figure 4 As shown, Figure 4 A schematic diagram of a flow chart of another embodiment of a method for locating a power distribution line fault provided by the present invention. A method for locating a power distribution line fault, the method comprising:

[0136] S301: Obtain the line impedance value of each line section and the voltage and current values ​​of the distribution network under normal operating conditions.

[0137] For example, in a medium voltage distribution network, according to the structure of the distribution network, a medium voltage distribution network system model is established using PSCAD simulation software, including 1 110kV / 10kV main transformer (100MVA, 10kV side rated current 5773A), 4 sections of 10kV lines, voltage ratio 10kV / 0.4kV, capacity of 100MVA, and 4 distribution transformers (PB01~PB04) with an impedance voltage percentage of 10%. PB01~PB04 correspond to 4 nodes N1~N4. Figure 5 As shown, Figure 5 It is another schematic diagram of the distribution network simulation calculation model provided by the present invention.

[0138] The length of the four 10kV lines is 1km, and each line is divided into two sections. The line model reference model is LGJ-120 0.4kV low-voltage overhead conductor setting. The impedance parameter of this model conductor is 0.2496+j0.1781Ω / km. An AB phase short-circuit fault is set between N2-N3, and the transition resistance is set to 1Ω. The phase-to-phase short-circuit fault current mutation threshold is set to 10% of the rated current of the main transformer, that is, 577A.

[0139] The fault section is located according to the distribution line fault location method. In normal operation, the line impedance values ​​of each line section are all 0.2496+j0.1781Ω, the line resistance is all R=0.2496Ω, and the line reactance is all X=0.1781Ω.

[0140] S302: Determine the type of phase-to-phase fault according to the current value.

[0141] For example, the positioning equipment measures the voltage and current values ​​of the line main transformer. After a phase-to-phase short circuit fault occurs in the N2-N3 line section, the currents of phases A and B suddenly change from 139A to 1610A and 1658A, with sudden increases of 1471A and 1519A, respectively, both exceeding the sudden increase threshold of 577A, and the current of phase C has no obvious change. It is determined that a phase-to-phase short circuit fault occurs in phases AB.

[0142] S303: Acquire power parameter data of each node in the distribution network under fault status.

[0143] Exemplarily, in a fault state, the positioning device requests the three-phase low-voltage side voltage data and the three-phase low-voltage side current data of the low-voltage side of each node distribution transformer in the interval, as shown in Table 6:

[0144] Table 6 Power parameter data of each node

[0145]

[0146] S304: Under any fault phase, determine the low-voltage side positive sequence current and the low-voltage side negative sequence current of the current fault phase according to the three-phase low-voltage side current data of the current node.

[0147] For example, the node reference voltage and current calculation process of the N1 node is taken as an example:

[0148] Select the fault phase A, and use the symmetrical component method to determine the positive, negative, and zero sequence components of the low-voltage side current of phase A based on the three-phase low-voltage side current data of node N1:

[0149]

[0150] in, are the positive, negative and zero sequence components of the current on the low voltage side of phase A, is the three-phase current of A, B, C on the low voltage side, a=e j1200 、a 2 =e j2400 .

[0151] Furthermore, since the high-voltage side of the distribution transformer is connected in a triangle, the zero-sequence current on the low-voltage side cannot pass through the distribution transformer, so only the positive-sequence component and the negative-sequence component are calculated. Substituting the data in the above table, the low-voltage side positive-sequence current and the low-voltage side negative-sequence current of phase A can be obtained as shown below:

[0152]

[0153] S305: Determine the high-voltage side positive-sequence current and the high-voltage side negative-sequence current according to the low-voltage side positive-sequence current and the low-voltage side negative-sequence current.

[0154] Exemplarily, the low-voltage side positive sequence current and the low-voltage side negative sequence current are converted into the high-voltage side positive sequence current and the high-voltage side negative sequence current as shown in the following formula:

[0155] in, is the positive sequence current on the high voltage side, is the negative sequence current on the high voltage side.

[0156] S306: Determine the three-phase high-voltage side current of the current node according to the high-voltage side positive-sequence current and the high-voltage side negative-sequence current.

[0157] For example, the positive sequence current and negative sequence current on the high voltage side of the distribution transformer are synthesized into the current of the A, B, and C phase lines on the high voltage side. The three-phase high-voltage side current is shown in the following formula:

[0158] but

[0159] S307: Determine the low-voltage side positive-sequence voltage and the low-voltage side negative-sequence voltage of the current fault phase voltage according to the three-phase low-voltage side voltage data of the current node and the low-voltage side positive-sequence current and the low-voltage side negative-sequence current.

[0160] Exemplarily, the fault phase A is selected, and the positive sequence, negative sequence, and zero sequence components of the low-voltage side voltage of the phase A current are determined according to the three-phase low-voltage side voltage data of the N1 node using the symmetrical component method, as shown in the following formula:

[0161]

[0162] in, They are the positive sequence, negative sequence and zero sequence components of the low voltage side voltage respectively.

[0163] Furthermore, the 10kV side of the distribution transformer is converted to the 0.4kV low-voltage side to determine the positive sequence voltage on the low-voltage side, as shown in the following formula:

[0164]

[0165] in, is the positive sequence voltage on the low voltage side, is the positive sequence voltage component on the low voltage side, is the positive sequence current component on the low voltage side, X T2+ The positive sequence impedance of the distribution transformer from the high voltage side to the low voltage side is 0.064jΩ (only the leakage reactance is considered, and the excitation reactance and winding resistance are ignored).

[0166] Furthermore, the 10kV side of the distribution transformer is converted to the 0.4kV low-voltage side to determine the negative sequence voltage on the low-voltage side, as shown in the following formula:

[0167]

[0168] in, is the negative sequence voltage on the low voltage side, is the negative sequence voltage component on the low voltage side, is the negative sequence current on the low voltage side, X T2- The negative sequence impedance of the high voltage side of the distribution transformer converted to the low voltage side is 0.064jΩ.

[0169] S308: Determine the high-voltage side positive-sequence voltage and the high-voltage side negative-sequence voltage according to the low-voltage side positive-sequence voltage and the low-voltage side negative-sequence voltage.

[0170] Exemplarily, the low-voltage side positive sequence voltage is converted to the high-voltage side positive sequence voltage, and the high-voltage side positive sequence voltage is determined according to the following formula:

[0171] in, is the positive sequence voltage on the high voltage side, and k is the distribution transformer ratio.

[0172] Furthermore, the negative sequence voltage on the low voltage side is converted to the negative sequence voltage on the high voltage side, and the negative sequence voltage on the high voltage side is determined according to the following formula:

[0173] in, is the negative sequence voltage on the high voltage side, and k is the distribution transformer ratio.

[0174] S309: Determine the three-phase high-voltage side voltage of the current node according to the high-voltage side positive-sequence voltage and the high-voltage side negative-sequence voltage.

[0175] Exemplarily, the zero-sequence impedance on the high-voltage side is very small, and the zero-sequence voltage is approximately 0, then the three-phase high-voltage side voltage synthesized by the positive-sequence voltage on the high-voltage side and the negative-sequence voltage on the high-voltage side is determined according to the following formula:

[0176]

[0177] in, is the A phase voltage on the high voltage side, is the voltage of phase B on the high voltage side, is the C phase voltage on the high voltage side.

[0178] S310: Determine a node reference voltage of a current node according to the voltage amplitude of the three-phase high-voltage side voltage.

[0179] Exemplarily, the node reference voltage is the voltage amplitude of each phase, namely 5687V, 5278V and 5859V.

[0180] S311: Determine the node user active power and the node user reactive power of the current node according to the product of the three-phase high-voltage side current and the three-phase high-voltage side voltage.

[0181] For example, the three-phase apparent power of the current node is obtained by multiplying the three-phase high-voltage side current and the three-phase high-voltage side voltage, and its real part and imaginary part are respectively the node user active power and node user reactive power of the node. For phase A of PB01:

[0182]

[0183] Then the active power of the A phase node user of the N1 node (PB01) is 182.64kW, and the reactive power of the node user is 212.3kvar.

[0184] Similarly, the node reference voltage, node user power and node user reactive power of each node are obtained according to the above calculation process.

[0185] S312: From the end node on the load side of the line section to the starting node on the power supply side of the line section, determine the node active power and node reactive power of each node in turn according to the line impedance value of the line section where the current node is located, the node reference voltage of the node on the load side of the current line section, the node user active power and the node user reactive power.

[0186] Exemplarily, the node active power and node reactive power of each node are calculated one by one from the load side to the power supply side. For the load side terminal node N4, its node active power is equal to the node user active power of the node 38.163kW, and its node reactive power is equal to the node user reactive power of the node 28.020kvar.

[0187] When calculating the node active power and node reactive power of N3, the node (reactive) power of node N4 (the load side node of node N3) is first used to calculate the active (reactive) power loss of the N3-N4 section (the load side line section where the N3 node is located).

[0188] For the N3-N4 line section, the apparent power of the line section loss in the N3-N4 section is as follows: is the node active power of the load side node N4 in the N3-N4 interval, is the node reactive power of the load side node N4 in the N3-N4 interval, U is the node reference voltage of the load side node N4 in the N3-N4 interval, and Z N3-N4 is the line impedance value in the N3-N4 section.

[0189] Similarly, the power loss of each line section is calculated.

[0190] For node N3, the node active power is equal to the algebraic sum of the user active power of node N3, the active power lost in the load-side line section N3-N4 where node N3 is located, and the node active power of the adjacent node N4 on the load side of node N3, that is, 205.94+0.02+38.163=244.122kW. The node reactive power is equal to the user reactive power of node N3, the reactive power lost in the load-side line section N3-N4 where node N3 is located, and the node reactive power of the adjacent node N4 on the load side of node N3, that is, 156.662+0.014+28.02=184.696kvar. Similarly, the node active power and node reactive power of other nodes can be obtained.

[0191] S313: From the end node on the load side of the line section to the starting node on the power supply side of the line section, determine the node fault voltage of each node in turn according to the node reactive power, node active power of the adjacent nodes on the load side of the current node and the line impedance value of the load side line section where the current node is located.

[0192] Exemplarily, for the load-side end node N4, its node fault voltage is equal to its node reference voltage 5344V.

[0193] For the N3 node, its node fault voltage is calculated by the following formula:

[0194]

[0195] Among them, U g_N3 is the node fault voltage of node N3, U g_N4 is the node fault voltage of the load side adjacent node N4 of the node N3; N4 Q is the node active power of the load-side adjacent node N4 of node N3; N4 is the node reactive power of the load-side adjacent node N4 of node N3; R N3-N4 is the line resistance of the load side line section N3-N4 of the node N3; N3-N4 is the line reactance of the load side line section N3-N4 of node N3. Similarly, the node fault voltage of each node is calculated.

[0196] like Figure 6 As shown, Figure 6The present invention provides a schematic diagram of the structure of a distribution line fault location system according to an embodiment of the present invention. The distribution line fault location system 10 comprises:

[0197] The first acquisition module 11 is used to obtain the line impedance value of each line section and the current value of the distribution network under normal operating conditions. The phase-to-phase fault determination module 12 is used to determine the type of phase-to-phase fault based on the current value. The second acquisition module 13 is used to obtain the power parameter data of each node of the distribution network under a fault state. The node user active power and node user reactive power determination module 14 is used to determine the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data under any fault phase. The node fault voltage determination module 15 is used to determine the node fault voltage of each node according to the line impedance value, node user active power and node user reactive power of the line section where the current node is located. The fault line section determination module 16 is used to locate the fault line section based on the comparison between the node reference voltage and the node fault voltage.

[0198] Exemplarily, the first acquisition module 11 acquires the line impedance value of each line section and the current value of the distribution network under normal operating conditions. Further, in the phase-to-phase fault determination module 12, if each line section is in a medium-voltage distribution network, it is determined that the current values ​​of any two phases at the main transformer outlet are greater than the phase-to-phase short-circuit fault current mutation threshold, and the remaining one phase is less than or equal to the phase-to-phase short-circuit fault current mutation threshold, then a bidirectional phase-to-phase short-circuit fault occurs; it is determined that the current values ​​of the three phases at the main transformer outlet are all greater than the phase-to-phase short-circuit fault current mutation threshold, then a three-phase phase-to-phase short-circuit fault occurs; if each line section is in a low-voltage distribution network, it is determined that the current values ​​of any two phases at the distribution transformer outlet are greater than the phase-to-phase short-circuit fault current mutation threshold, and the remaining one phase is less than or equal to the phase-to-phase short-circuit fault current mutation threshold, then a bidirectional phase-to-phase short-circuit fault occurs; it is determined that the current values ​​of the three phases at the distribution transformer outlet are all greater than the phase-to-phase short-circuit fault current mutation threshold, then a three-phase phase-to-phase short-circuit fault occurs. Furthermore, in the second acquisition module 13, in the fault state, it is determined that it is in the low-voltage distribution network, then the voltage data, active power data, and reactive power data of the user end of each node in the interval are obtained; in the fault state, it is determined that it is in the medium-voltage distribution network, then the three-phase low-voltage side voltage data and three-phase low-voltage side current data of the low-voltage side of each node distribution transformer are obtained. Further, in the node user active power and node user reactive power determination module 14, under any fault phase, the node reference voltage, node user active power, and node user reactive power of the current node are determined according to the power parameter data. Further, in the node fault voltage determination module 15, from the end node on the load side of the line section to the starting node on the power supply side of the line section, the node active power and node reactive power of each node are determined in sequence according to the line impedance value of the line section where the current node is located, the node reference voltage of the node on the load side of the current line section, the node user active power and the node user reactive power; from the end node on the load side of the line section to the starting node on the power supply side of the line section, the node fault voltage of each node is determined in sequence according to the node reactive power of the adjacent node on the load side of the current node, the node active power and the line impedance value of the load side line section where the current node is located. Finally, in the fault line section determination module 16, the comparison between the node reference voltage and the node fault voltage of each node is determined in sequence from the load side to the power supply side; if the first node fault voltage is less than the node reference voltage and the node fault voltage is greater than the fault characteristic threshold, the load side line section where the node corresponding to the node fault voltage is located is the fault line section; if the first node fault voltage is greater than or equal to the node reference voltage and the node fault voltage is less than or equal to the fault characteristic threshold, the load side line section where the node corresponding to the node fault voltage is located is the non-fault line section.

[0199] like Figure 7 As shown, Figure 7The storage medium 20 stores at least one computer program 21, which is executed by a processor to implement the following. Figure 1 , Figure 2 and Figure 4 In one embodiment, the storage medium 20 may be a storage chip, a hard disk, a mobile hard disk, a USB flash drive, an optical disk, or other readable and writable storage tools, or a server, etc.

[0200] 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).

[0201] 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.

[0202] 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 distribution line fault, characterized in that: The method comprises: Obtain the line impedance value of each line section and the current value of the distribution network under normal operating conditions; determining a phase-to-phase fault type according to the current value; Obtain power parameter data of each node in the distribution network under fault conditions; Under any fault phase, determining the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data; Determine the node fault voltage of each node according to the line impedance value, node user active power and node user reactive power of the line section where the current node is located; The faulty line section is located according to the comparison between the node reference voltage and the node fault voltage.

2. A method for locating a distribution line fault according to claim 1, characterized in that: Determining the interphase fault type according to the current value specifically includes: If each line section is in a medium voltage distribution network, it is determined that the current values ​​of any two phases at the main transformer outlet are greater than the phase-to-phase short circuit fault current mutation threshold, and the remaining phase is less than or equal to the phase-to-phase short circuit fault current mutation threshold, then a bidirectional phase-to-phase short circuit fault occurs; it is determined that the current values ​​of the three phases at the main transformer outlet are all greater than the phase-to-phase short circuit fault current mutation threshold, then a three-phase phase-to-phase short circuit fault occurs; If each line section is in a low-voltage distribution network, it is determined that the current values ​​of any two phases at the distribution transformer outlet are greater than the phase-to-phase short-circuit fault current mutation threshold, and the remaining phase is less than or equal to the phase-to-phase short-circuit fault current mutation threshold, then a bidirectional phase-to-phase short-circuit fault occurs; it is determined that the current values ​​of the three phases at the distribution transformer outlet are all greater than the phase-to-phase short-circuit fault current mutation threshold, then a three-phase phase-to-phase short-circuit fault occurs.

3. A method for locating a distribution line fault according to claim 2, characterized in that: The obtaining of power parameter data of each node in the distribution network under a fault state specifically includes: In the fault state, if it is determined to be in a low-voltage distribution network, the voltage data, active power data, and reactive power data of the user end of each node in the interval are obtained; In the fault state, it is determined that the medium voltage distribution network is in operation, and the three-phase low voltage side voltage data and the three-phase low voltage side current data of the low voltage side of each node distribution transformer are obtained.

4. A method for locating a distribution line fault according to claim 3, characterized in that: Under any of the fault phases, determining the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data specifically includes: Under any fault phase, determining the node reference voltage of the current node according to the voltage data of the user end of the current node in the interval; Determine the node user active power of the current node according to the algebraic sum of the active power data of the current node user end in the interval; The node user reactive power of the current node is determined according to the algebraic sum of the reactive power data of the current node user end in the interval.

5. A method for locating a distribution line fault according to claim 3, characterized in that: Under any of the fault phases, determining the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data specifically includes: Under any fault phase, determine the low-voltage side positive sequence current and the low-voltage side negative sequence current of the current fault phase current according to the three-phase low-voltage side current data of the current node; Determine the high-voltage side positive-sequence current and the high-voltage side negative-sequence current according to the low-voltage side positive-sequence current and the low-voltage side negative-sequence current; Determine the three-phase high-voltage side current of the current node according to the high-voltage side positive-sequence current and the high-voltage side negative-sequence current; Determine the low-voltage side positive-sequence voltage and the low-voltage side negative-sequence voltage of the current fault phase voltage according to the three-phase low-voltage side voltage data of the current node and the low-voltage side positive-sequence current and the low-voltage side negative-sequence current; Determine the high-voltage side positive-sequence voltage and the high-voltage side negative-sequence voltage according to the low-voltage side positive-sequence voltage and the low-voltage side negative-sequence voltage; Determine the three-phase high-voltage side voltage of the current node according to the high-voltage side positive-sequence voltage and the high-voltage side negative-sequence voltage; Determine a node reference voltage of a current node according to the voltage amplitude of the three-phase high-voltage side voltage; The node user active power and the node user reactive power of the current node are determined according to the product of the three-phase high-voltage side current and the three-phase high-voltage side voltage.

6. A method for locating a distribution line fault according to claim 4 or 5, characterized in that: The determining of the node fault voltage of each node according to the line impedance value, the node user active power and the node user reactive power of the line section where the current node is located specifically includes: From the end node on the load side of the line section to the start node on the power supply side of the line section, according to the line impedance value of the line section where the current node is located, the node reference voltage of the node on the load side of the current line section, the node user active power and the node user reactive power, the node active power and the node reactive power of each node are determined in sequence; From the end node on the load side of the line section to the starting node on the power supply side of the line section, the node fault voltage of each node is determined in turn according to the node reactive power, node active power of the adjacent nodes on the load side of the current node and the line impedance value of the load side line section where the current node is located.

7. A method for locating a distribution line fault according to claim 6, characterized in that: The method of determining the node active power and node reactive power of each node in sequence from the end node on the load side of the line section to the start node on the power supply side of the line section according to the line impedance value of the line section where the current node is located, the node voltage of the node on the load side of the current line section, the node user active power and the node user reactive power specifically includes: Determine the node active power and node reactive power of the end node according to the node user active power and node user reactive power of the end node on the line load side; According to the line impedance value of the load side line section where the non-end node on the line load side is located, the node reference voltage of the load side node, the node user active power and the node user reactive power, the node active power and the node reactive power of the non-end node are determined in turn.

8. A method for locating a distribution line fault according to claim 7, characterized in that: The determining the node active power and the node reactive power of the non-end node in sequence according to the line impedance value of the load side line section where the non-end node on the line load side is located, the node reference voltage of the load side node, the node user active power and the node user reactive power, specifically includes: Determine the apparent power lost in the line section according to the line impedance value of the load-side line section where the non-terminal node on the load side of the line is located, the node reference voltage of the load-side node, the node active power and the node reactive power; Determining the active power of the line section loss and the reactive power of the line section loss according to the apparent power of the line section loss; Determine the node active power of the current node according to the algebraic sum of the node user active power of the current node, the active power lost in the load-side line section where the current node is located, and the node active power of the nodes adjacent to the load side of the current node; The node reactive power of the current node is determined based on the algebraic sum of the node user reactive power of the current node, the reactive power lost in the load-side line section where the current node is located, and the node reactive power of the nodes adjacent to the load side of the current node.

9. A method for locating a distribution line fault according to claim 8, characterized in that: Determining the apparent power lost in the line section according to the line impedance value of the load side line section where the non-terminal node on the load side of the line is located, the voltage data of the load side node, the node active power and the node reactive power specifically includes: according to Determine the apparent power lost in the line section, where S L is the apparent power loss in the line section; P NL is the node active power of the load side node in the line section; Q NL is the node reactive power of the load side node in the line section; U T-NL is the node reference voltage of the load side node of the line section; Z L is the line impedance value of the line section.

10. A method for locating a distribution line fault according to claim 8, characterized in that: The node fault voltage of each node is determined in sequence from the end node on the load side of the line section to the start node on the power supply side of the line section according to the node reactive power and node active power of the adjacent nodes on the load side of the current node and the line impedance value of the load side line section where the current node is located, specifically including: Determining a node fault voltage of an end node according to the node reference voltage of the end node on the load side of the line section; The node fault voltage of the non-terminal node is determined according to the line impedance value of the load-side line section where the non-terminal node on the load side of the line section is located, and the node active power and node reactive power of the node adjacent to the load side of the current non-terminal node.

11. A method for locating a distribution line fault according to claim 10, characterized in that: Determining the node fault voltage of the non-end node according to the line impedance value of the load-side line section where the non-end node on the load side of the line section is located, and the node active power and node reactive power of the node adjacent to the load side of the current non-end node specifically includes: according to Determine the node fault voltage of the non-terminal node, where U g_Nx is the node fault voltage of the node; U J_Nnx is the node fault voltage of the adjacent node on the load side of the node; P Nnx is the node active power of the adjacent node on the load side of the node; Q Nnx is the node reactive power of the adjacent nodes on the load side of the node; R Lnext is the real part of the line impedance of the line section on the load side of the node; X Lnext It is the imaginary part of the line impedance of the line section on the load side of the node.

12. A method for locating a distribution line fault according to claim 10, characterized in that: The locating the faulty line section according to the comparison between the node reference voltage and the node fault voltage specifically includes: Determine the comparison between the node reference voltage and the node fault voltage of each node in turn from the load side to the power supply side; If the first node fault voltage is less than the node reference voltage, and the node fault voltage is greater than the fault characteristic threshold, then the load-side line section where the node corresponding to the node fault voltage is located is the fault line section; If the first node fault voltage is greater than or equal to the node reference voltage, and the node fault voltage is less than or equal to the fault characteristic threshold, then the load side line section where the node corresponding to the node fault voltage is located is a non-fault line section.

13. A distribution line fault location system, characterized in that: The system comprises: The first acquisition module is used to obtain the line impedance value of each line section and the current value of the distribution network under normal operating conditions; A phase-to-phase fault determination module, used to determine the type of phase-to-phase fault according to the current value; The second acquisition module is used to obtain power parameter data of each node in the distribution network under a fault state; A node user active power and node user reactive power determination module, used to determine the node reference voltage, node user active power and node user reactive power of the current node according to the power parameter data under any fault phase; A node fault voltage determination module, used to determine the node fault voltage of each node according to the line impedance value, the node user active power and the node user reactive power of the line section where the current node is located; The fault line section determination module is used to locate the fault line section according to the comparison between the node reference voltage and the node fault voltage.

14. 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 12.

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