A double-terminal ranging method for single-phase ground faults in overhead-cable hybrid lines

Abstract

The invention relates to a double-end range finding method for a single-phase earth fault of an overhead-cable mixed line. The method comprises: according to positive-sequence components of three-phase voltages and currents of a front end and a tail end in a normal condition of an overhead-cable mixed line, non-synchronized angles delta of currents at the two ends of the overhead-cable mixed line are calculated; power frequency components of the three-phase voltages and currents at the front end and the tail end of the overhead-cable mixed line after a single-phase earth fault are extracted by using a differential fourier algorithm; symmetric component conversion is carried out on the power frequency components of the three-phase voltages and currents at the front end and the tail end of the overhead-cable mixed line after the single-phase earth fault to obtain sequence components of the voltages and currents at the front end and the tail end of the overhead-cable mixed line after the single-phase earth fault; a sequence component of the single-phase earth fault current of the overhead-cable mixed line is calculated; and the fault point position is determined based on a one-dimensional iterative searching algorithm. Compared with the prior art, the provided method has characteristics of accurate range finding and high efficiency.

Description

technical field [0001] The invention belongs to the technical field of power system fault detection, and in particular relates to a double-terminal ranging method for a single-phase ground fault of an overhead-cable hybrid line. Background technique [0002] Transmission and distribution lines are an important part of the power system. Once a major fault occurs, it will directly affect the normal production and life of the society and cause major economic losses. Therefore, it is of great significance for the stable and reliable operation of the power system to quickly and accurately locate the fault point and take effective measures to eliminate the fault in time. [0003] The line fault with the highest probability of occurrence in the power grid is the single-phase ground fault. At the same time, due to the impact of the urban environment and topography, there are more and more applications of overhead line-cable hybrid lines, and the discontinuity of line parameters mak...

AI Technical Summary

Problems solved by technology

Existing fault location methods for overhead-cable hybrid lines are mainly based on fault analysis methods, but most of them use lumped parameter models for calculation, ignoring the influence of line distributed capacitance, resulting in inaccurate ranging results

At the same time, the traditional positioning methods regard the transition impedance as pure resistance. However, the transition impedance of single-phase ground faults is more complex, and there may be inductive components, which brings new difficulties and challenges to fault location technology.

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