Ground fault line and type identification method and device based on ultra-low frequency signal

Abstract

The invention discloses a ground fault line and type identification method and device based on an ultra-low frequency signal. The method comprises the steps: obtaining a zero-sequence voltage ultra-low frequency signal and a zero-sequence current ultra-low frequency signal of each line; selecting an absolute value of the peak value of the zero-sequence current ultralow-frequency signal as a representative value of a corresponding line; if the representative values are less than a current threshold value, determining that a single-phase earth fault does not occur, and otherwise, determining that the line with the maximum representative value is a faulty line; acquiring a zero-sequence voltage power frequency signal of the fault line so as to determine a fault angle; adaptively selecting anultra-low frequency characteristic frequency band based on the fault angle; calculating the ratio of the zero-sequence voltage signal energy to the zero-sequence current signal energy of the fault line in the characteristic frequency band, taking the ratio as the characteristic quantity for estimating the transition resistance, and determining the fault type based on the characteristic quantity. According to the invention, the line with the ground fault can be accurately identified, and the fault type can be identified on the basis of accurate line selection.

Description

technical field [0001] The invention belongs to the technical field of power fault detection, and more specifically relates to a method and device for identifying ground fault lines and types based on ultra-low frequency signals. Background technique [0002] According to statistics, single-phase ground faults account for more than 70% of distribution network short-circuit faults. my country's distribution network adopts different neutral point grounding methods according to the proportion of overhead lines and cables. The distribution network dominated by overhead lines mainly adopts small current grounding methods, including ungrounded neutral points and grounding through arc suppression coils. Two, the cable-based distribution network mainly adopts the grounding method of the neutral point through the arc suppression coil or the grounding method of the small resistance. When a single-phase ground fault occurs, arcing may occur at the fault point. It is necessary to accura...

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