Earth fault judging method for overhead line fault indicator

Abstract

The invention discloses an earth fault judging method for an overhead line fault indicator in the technical field of power grids. A voltage signal on an open-delta side of a three-phase potential transformer on a bus of a power grid to be detected is introduced into a signal output end of a quintuple harmonic generator; a plurality of fault indicators are arranged on a plurality of sections of overhead power lines of the power grid to be detected; and after a permanent earth fault reaches the judging time, the quintuple harmonic generator outputs specific coding waves communicating between a system power supply and a fault line of an earth point to the power grid to be detected through the open-delta side of the three-phase potential transformer so as to realize earth fault positioning. The earth fault judging method avoids the defects of the conventional fault indicators in distribution network system application and improves the accuracy of judging the earth fault.

Description

Technical field [0001] The invention relates to a method in the technical field of power grids, in particular to a ground fault determination method for overhead line fault indicators. Background technique [0002] Most of the line faults in the power grid occur in the distribution network, which directly affects social production. It is very important to locate the fault point in time and accurately. In recent years, the application of overhead line fault indicators has brought great convenience to fault finding and has been widely used in power grids. However, most of the distribution networks in my country are neutral point ungrounded systems or low current grounded systems. For short-circuit faults with large fault currents, the fault indicator has a certain accuracy. For ground faults, the accuracy of the fault indicator is greatly reduce. Although product manufacturers and research institutions have conducted in-depth research on this issue, they have not made breakthrough...

AI Technical Summary

Problems solved by technology

But its fault judgment method has certain shortcomings: when a ground fault occurs in the system, the fifth harmonic signal of the system itself is small, and it is easily affected by the fault type and the power grid system, and the fault judgment is unreliable and accurate.

Most of these technologies use simple analog circuits to sample the fault signal of the line itself to judge the fault of the line. , has a certain degree of accuracy, but for ground faults with small fault signal characteristics, it cannot be accurately judged

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