On-line positioner of small current earth fault

Abstract

The invention discloses an on-line positioning method of small current earth fault and a positioner based on the positioning method. The method is suitable for a 3 to 60 kV neutral non-effective grounding electrical network. When a line is in operation with single phase earth fault, a 130 to 230 Hz (excluding power frequency of integer times of 50 Hz) AC signal is filled into a transformer station PT (potential transformer), voltage phasor of the filled signal is measured in a transformer station, current phasor of the filled signal is measured in a line, thus the section position of a fault point is determined according to the phase relationship of the filled signal voltage phasor and the filled signal current phasor. The positioner in the present invention comprises a host computer and a lower computer. The host computer is installed in the transformer station, and is used for filling 130 to 230 Hz (excluding power frequency of integer times of 50 Hz) AC signal into the transformer station PT and measuring the voltage phasor of bus filling signal. The lower computer is installed on the line, and is used for measuring current phasor of the filled signal. The lower computer uploads a measuring result to the host computer, and the host computer carries out phasor analysis and completes positioning calculation. The on-line positioning method of small current earth fault and the positioner based on the positioning method provided in the invention have the advantages of mature technology and high reliability.

Description

technical field [0001] The invention belongs to the technical field of electric power grounding fault detection, and specifically relates to an online positioning method and positioning device for a small current grounding fault, which is suitable for 3-60kV neutral point non-effectively grounded power grids, and can be used for fault detection when a single-phase grounding fault occurs. Accurate positioning while running. 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 live fault location. [0003] The problem of o...

AI Technical Summary

Problems solved by technology

The former adopts the offline positioning method, which needs power failure injection signal, which cannot meet the requirements of on-line positioning with faulty operation on site

The latter uses zero-sequence voltage and zero-sequence current phasor comparison for online positioning, but it needs to collect three-phase current and synthesize zero-sequence current, the equipment is complex and costly, and on-site operation is inconvenient

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