CN-122017464-A - Quick positioning method for cable branch box ground fault

CN122017464ACN 122017464 ACN122017464 ACN 122017464ACN-122017464-A

Abstract

The invention discloses a quick positioning method for a ground fault of a cable branch box, which belongs to the technical field of measurement or test of electric variables and comprises the steps of taking each cable branch box in a power distribution system as a node, establishing a physical connection topology comprising a ground reference point, defining a virtual fault channel for each fault current path between each node and the ground reference point, generating a virtual channel network, acquiring zero sequence current measured values of each preset monitoring node, distributing the zero sequence current measured values to the virtual channel network, calculating to obtain virtual branch currents of each virtual fault channel, carrying out verification screening by combining the acquired impedance parameters of each virtual fault channel to obtain a target virtual channel set, mapping the target virtual channel set to the physical connection topology, and determining and outputting the physical position of the fault point. By adopting the virtual channel network to simulate the fault current path and performing bimodal verification screening, the rapid, automatic and accurate positioning of the ground fault of the complex power distribution network can be realized.

Inventors

LIU HUAN
LIU YUNIAN

Assignees

亚正电气集团有限公司

Dates

Publication Date: 20260512
Application Date: 20260317

Claims (10)

1. A method for quickly locating a cable feeder pillar ground fault, the method comprising: Taking each cable branch box in the power distribution system as a node, and establishing a physical connection topology comprising a grounding reference point; Defining a virtual fault channel for each fault current path between each node and a ground reference point based on the physical connection topology, and generating a virtual channel network; Acquiring zero sequence current measured values of all preset monitoring nodes; distributing the zero sequence current measured value of each monitoring node to the virtual channel network, and calculating to obtain virtual branch current of each virtual fault channel; Obtaining impedance parameters of each virtual fault channel, and performing verification and screening by combining the virtual channel network, the virtual branch current and the zero sequence current measured value to obtain a target virtual channel set; and mapping the target virtual channel set into the physical connection topology, and determining and outputting the physical position of the fault point.
2. The method for quickly positioning a ground fault of a cable breakout box according to claim 1, wherein the establishing a physical connection topology using each cable breakout box in the power distribution system as a node comprises: Acquiring line connection relation data and equipment ledger data in a power distribution system; Identifying and checking the electrical connection relation among the cable branch boxes based on the line connection relation data and the equipment ledger data, and generating a connection relation matrix; And determining a grounding reference point in the network according to the connection relation matrix and a preset grounding reference point configuration rule, so as to construct a physical connection topology.
3. The method for quickly locating a ground fault of a cable feeder box according to claim 2, wherein said defining a virtual fault path for each fault current path between each node and a ground reference point based on the physical connection topology, generating a virtual path network comprises: Traversing an electrical path from each node to a ground reference point based on the physical connection topology; Defining a virtual fault channel for each identified electrical path, and assigning a unique channel identification to each virtual fault channel; and logically combining all the defined virtual fault channels according to the physical connection relation to generate a virtual channel network representing all fault current circulation paths.
4. A method for quickly locating a ground fault in a cable feeder box according to claim 3, wherein the obtaining the zero sequence current measurement values of each preset monitoring node comprises: Selecting a cable branch box node meeting preset conditions as a monitoring node; According to a unified synchronous time reference, acquiring zero sequence current waveform data of a monitoring node in a preset time window after a fault occurs; And preprocessing the zero sequence current waveform data of each monitoring point to obtain zero sequence current measured values of each monitoring node.
5. The method for quickly positioning a ground fault of a cable trunk according to claim 4, wherein the distributing the zero sequence current measurement values of each monitoring node to the virtual channel network, and calculating the virtual branch current of each virtual fault channel comprises: obtaining the subordinate relations between each virtual fault channel and each monitoring node in the virtual channel network, and generating a monitoring node coverage relation matrix; Based on the monitoring node coverage relation matrix and zero sequence current measured values of all the monitoring nodes, calculating to obtain initial branch current vectors of all the virtual fault channels through a current distribution algorithm; Performing topology constraint correction on the initial branch current vector according to the topology mapping relation between the physical connection topology and the virtual channel network to generate a correction coefficient vector; And carrying out weighted calculation on the initial branch current vector by using the correction coefficient vector to obtain and output virtual branch currents of each virtual fault channel.
6. The method for quickly positioning a ground fault of a cable trunk according to claim 5, wherein the obtaining the impedance parameters of each virtual fault channel, and performing verification screening to obtain a target virtual channel set by combining the virtual channel network, the virtual branch current and the zero sequence current measured values comprises: Obtaining impedance parameters of each virtual fault channel, and calculating fault distances corresponding to each virtual fault channel by combining the virtual channel network and the virtual branch current to generate a fault distance set; performing time-frequency analysis on transient components in the zero sequence current measured value, and extracting transient energy characteristics; Mapping the transient energy characteristics to the virtual channel network, analyzing the distribution difference of the same transient energy characteristics on different virtual fault channels, and generating channel energy difference vectors; And carrying out bimodal verification on each virtual fault channel according to the calculated residual error of each fault distance in the barrier distance set and the channel energy difference vector, and screening out a target virtual channel set.
7. The method for quickly positioning a ground fault of a cable trunk according to claim 6, wherein the step of performing bimodal verification on each virtual fault channel according to each fault distance in the set of fault distances and the channel energy difference vector, and the step of screening out the set of target virtual channels includes: extracting residual errors of the corresponding fault distances of each virtual fault channel from the barrier distance set, and generating a channel residual error vector; Normalizing the channel energy difference vector to obtain a channel energy difference index vector; weighting calculation is carried out on the channel residual error vector and the channel energy difference index vector of the corresponding virtual fault channel, so that a confidence score of the corresponding virtual fault channel is obtained; and screening the virtual fault channels with the confidence scores larger than a preset scoring threshold value to obtain a target virtual channel set.
8. The method for quickly positioning a ground fault of a cable feeder pillar according to claim 7, wherein the weighting calculation is performed on a channel residual vector and a channel energy difference index vector of a corresponding virtual fault channel to obtain a confidence score of the corresponding virtual fault channel, and further comprising: Identifying the current shunt characteristic of the virtual channel network, and calculating to obtain a shunt interference compensation coefficient; And compensating and adjusting the confidence score by using the shunt interference compensation coefficient.
9. The method for quickly locating a ground fault of a cable feeder pillar according to claim 7, wherein mapping the target virtual channel set into the physical connection topology, determining and outputting a fault point physical location comprises: sorting the confidence scores in the target virtual channel set from large to small, and selecting a virtual fault channel corresponding to the confidence score of the first sorting as a main judging channel; Mapping the main judgment channel into the physical connection topology to obtain a line section sequence; Determining physical position points in the line section sequence according to the fault distance corresponding to the main judging channel; And performing cross verification on the physical location point and the virtual fault channel in the target virtual channel set, and outputting the physical location of the fault point based on a verification result.
10. A cable breakout box ground fault quick location system, the system comprising: The topology construction module is used for establishing a physical connection topology containing a grounding reference point by taking each cable branch box in the power distribution system as a node; The channel network generation module is used for defining a virtual fault channel for each fault current path between each node and the ground reference point based on the physical connection topology, and generating a virtual channel network; The zero-sequence current acquisition module is used for acquiring zero-sequence current measured values of all preset monitoring nodes; The virtual branch current calculation module is used for distributing the zero sequence current measured value of each monitoring node to the virtual channel network and calculating to obtain the virtual branch current of each virtual fault channel; the target channel screening module is used for acquiring impedance parameters of each virtual fault channel, and performing verification screening by combining the virtual channel network, the virtual branch current and the zero sequence current measured value to obtain a target virtual channel set; and the fault location mapping module is used for mapping the target virtual channel set into the physical connection topology, and determining and outputting the physical location of the fault point.

Description

Quick positioning method for cable branch box ground fault Technical Field The invention relates to the technical field of measurement or test of electric variables, in particular to a quick positioning method for a cable branch box ground fault. Background The cable branch box is key equipment for realizing tapping and conversion of cable lines in a power distribution network, and quick and accurate positioning of the ground faults is important for guaranteeing power supply reliability and maintenance and overhaul safety. In the prior art, the localization of such faults is mostly dependent on the analysis and calculation of the electrical measurement signals. In the prior art, a monitoring device is usually installed at an outlet of a transformer substation or a few key nodes, and single-end or double-end ranging is performed by measuring zero sequence current or voltage signals generated by faults and combining line impedance parameters. Another common approach is to rely on manual inspection or injection of specific signals for segment-by-segment investigation to determine the specific segment where the fault occurred. However, the prior art solutions have obvious technical drawbacks. The accuracy of the impedance-based ranging method is seriously dependent on accurate line parameters, and significant errors are introduced by uncertainty of parameters in an actual network and change of transition resistance of a fault point. Schemes relying on a single or a few monitoring points are difficult to effectively cope with complex multi-branch structures of a power distribution network, and the actual flow path of fault current cannot be uniquely determined. The manual line inspection or signal injection rule is time-consuming and labor-consuming, and cannot meet the requirement of quickly recovering power supply. Disclosure of Invention In order to solve the problems, the invention provides a rapid positioning method for the ground fault of a cable branch box, which adopts a virtual channel network to simulate a fault current path and perform bimodal verification screening, so that the rapid, automatic and accurate positioning of the ground fault of a complex power distribution network can be realized. The above object can be achieved by the following scheme: A quick positioning method for a cable branch box ground fault comprises the steps of taking each cable branch box in a power distribution system as a node, establishing a physical connection topology comprising a ground reference point, defining a virtual fault channel for each fault current path between each node and the ground reference point based on the physical connection topology, generating a virtual channel network, obtaining zero sequence current measured values of each preset monitoring node, distributing the zero sequence current measured values of each monitoring node into the virtual channel network, calculating to obtain virtual branch currents of each virtual fault channel, obtaining impedance parameters of each virtual fault channel, combining the virtual channel network, the virtual branch currents and the zero sequence current measured values, performing verification screening to obtain a target virtual channel set, mapping the target virtual channel set into the physical connection topology, and determining and outputting the physical position of the fault point. The method comprises the steps of obtaining line connection relation data and equipment account data in a power distribution system, identifying and checking electrical connection relations among the cable branch boxes based on the line connection relation data and the equipment account data to generate a connection relation matrix, and determining a grounding reference point in a network according to the connection relation matrix and a preset grounding reference point configuration rule to construct the physical connection topology. Optionally, defining a virtual fault channel for each fault current path between each node and a ground reference point based on the physical connection topology, and generating a virtual channel network includes traversing electrical paths from each node to the ground reference point based on the physical connection topology, defining a virtual fault channel for each identified electrical path, and assigning a unique channel identifier to each virtual fault channel, and logically combining all defined virtual fault channels according to a physical connection relationship to generate a virtual channel network characterizing all fault current flow paths. Optionally, the acquiring the zero sequence current measured value of each preset monitoring node comprises selecting a cable branch box node meeting preset conditions as the monitoring node, acquiring the zero sequence current waveform data of the monitoring node in a preset time window after the fault occurs according to a uniform synchronous time reference, and preprocessing the zero sequence