Electric transmission line single-phase earth fault direction discriminating method based on instantaneous sampled values

Abstract

The invention discloses an electric transmission line single-phase earth fault direction discriminating method based on instantaneous sampled values. The electric transmission line single-phase earth fault direction discriminating method includes the steps of measuring fault-phase voltage sampled values, fault-phase current sampled values, fault-phase negative sequence current sampled values and zero sequence current sampled values at the protection installation position of an electric transmission line at sampling moments, calculating whether an electric transmission line single-phase earth fault direction criterion is workable or not through the fault-phase electric component sampled values at the three adjacent sampling moments, and if the electric transmission line single-phase earth fault direction criterion is workable, judging that a single-phase earth fault in the corresponding direction is generated on the electric transmission line. According to the electric transmission line single-phase earth fault direction discriminating method, the electric transmission line single-phase earth fault direction criterion is calculated only through the fault-phase electric component sampled values at the three adjacent sampling moments, a required data window is short, Fourier algorithm operation is not referred, the operation amount is small, and the calculating speed is high; the discriminating result is not influenced by the factors such as electric system oscillation, the fault position, transition resistance and a load current, and the fault direction of an electric transmission line single-phase earth fault is accurately discriminated.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for judging the direction of a single-phase grounding fault of a transmission line based on instantaneous sampling values. Background technique [0002] In the actual power grid, the fault point may be located in the opposite direction of the transmission line, or in the forward direction of the transmission line. If the fault point is located in the opposite direction of the transmission line, the relay protection device of the protected line will not act, but the relay protection device of the adjacent line will act to isolate the fault. If the fault point is located in the positive direction of the transmission line, the relay protection device of the protected line will act to isolate the fault on the protected line. The existing transmission line direction discrimination elements mainly include zero sequence power directional element,...

AI Technical Summary

Problems solved by technology

The existing transmission line direction discrimination elements mainly include zero sequence power directional element, negative sequence power directional element and zero sequence directional element, negative sequence directional element, zero sequence power directional element, negative sequence power directional element and zero sequence directional element, negative sequence The electrical quantities used in the directional element algorithm are all phasors, which require a whole wave of data windows to participate in the calculation, involving relatively complex Fourier algorithm calculations, so the traditional transmission line direction determination element is not real-time

If the fault is located at the opposite end of the protected line, the phase current power frequency variation, negative sequence current and zero sequence current protection criteria will act quickly. At this time, the traditional transmission line direction determination element will not be able to block the relay protection device in time. , will cause the relay protection device of the protected line to malfunction, cause the fault range to expand, and cause impact on the stability of the power grid, which is not conducive to the safe and stable operation of the power grid

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