Location method for single-phase earth fault of power distribution network based on genetic algorithm and location device

Abstract

The invention relates to a section location method and a location device for a single-phase earth fault of a power distribution network. The location method comprises the steps that terminals mounted at different positions of a line captures zero-sequence current transient signals at two cycles before and after zero-sequence current exceeds a start value, conduct wavelet transformation and reconstruction on the zero-sequence current transient signals, and are encoded according to reconstructed detail components, and a section where a fault point is located is searched by a genetic algorithm. The location device consists of the terminals and a master station, wherein the terminals are mounted on overhead line towers or in cable ring main units; input ends of the terminals receive zero-sequence current signals synthesized by phase current signals of CT (Current Transformer) secondary sides of distribution lines (comprising overhead lines and cables); the terminals are connected with the master station through optical fiber communication or mobile communication; and the master station is mounted in a transformer substation or a dispatch center, comprises an optical fiber communication module and a mobile communication module and receives signals sent by the terminals. The location method and the location device are mature in technology and high in reliability.

Description

technical field [0001] The invention belongs to the technical field of power system automation, and specifically relates to a section positioning method for a single-phase ground fault in a distribution network and a positioning device based on the positioning method. When a phase-to-ground fault occurs, accurately locate the fault section. Background technique [0002] The 3-60kV distribution network in my country widely adopts the non-effective neutral point grounding method, also known as the small current grounding system, and most of the faults in the small current grounding system are single-phase grounding faults. When a single-phase ground fault occurs, the ground current is very small, and it can continue to run for 1 to 2 hours under the fault condition, but the fault point must be found as soon as possible, which raises the problem of fault location. [0003] The problem of fault location in the distribution network has not been well resolved for a long time, and...

AI Technical Summary

Problems solved by technology

When a single-phase ground fault occurs, the ground current is very small, and it can continue to run for 1 to 2 hours under the fault condition, but the fault point must be found as soon as possible, which raises the problem of fault location

[0003] The problem of fault location in the distribution network has not been well resolved for a long time. The method of manual line inspection is often still used on site. Manual line inspection not only consumes a lot of manpower and material resources, but also prolongs the power outage time and affects the safety of power supply.

At present, there are three methods for automatic positioning on site. The first method is to inject a high-frequency signal from the PT and detect the signal along the line to determine the fault location. However, because the distributed capacitance of the line forms a path for the high-frequency signal, the positioning is not correct when it is grounded through a resistor. precise

The second method is to use the fault indicator. Since the fault indicator can only measure the phase current and cannot measure the zero-sequence current, it is better for short-circuit faults, but the accuracy of single-phase ground fault location is very low.

The third method is to install a smart switch with a built-in CT. Although this method can measure the zero-sequence current, the terminals and master stations operating on the market have simple algorithms that only judge whether the steady-state zero-sequence current exceeds a fixed value. The positioning accuracy of the arc suppression coil grounding system is very low

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