Distance protection method for non-transposition double-circuit lines on same tower

Abstract

The invention discloses a distance protection method for non-transposition double-circuit lines on the same tower. The method comprises the following steps of firstly, according to the existing fault phase selection method, accurately identifying the fault phase of the non-transposition double-circuit lines on the same tower; then, utilizing a six-phase impedance matrix obtained by an actual pole tower structure to calculate the average self-impedance, inter-phase mutual impedance, inter-line mutual impedance, and positive sequence impedance and zero sequence impedance of a virtual line; performing the fault calculation on the occurred fault type, and performing phase division and rectification on the protection area of each fault phase. The method has the advantage that the distance protection work of the non-transposition double-circuit lines on the same tower is controlled in the excellent state, and the important realistic meaning is realized for guaranteeing the safe and stable running of power systems.

Description

technical field [0001] The invention belongs to the field of power systems, and relates to the technical field of relay protection for double-circuit lines on the same tower without transposition, in particular to a distance protection method for double-circuit lines on the same tower without transposition. Background technique [0002] At present, double-circuit lines on the same tower are widely used in high-voltage power grids, and distance protection, as one of the mainstream backup protections, plays an extremely important role in the safe operation of double-circuit lines on the same tower. There is zero-sequence mutual inductance between ideally transposed double-circuit lines on the same tower. Under this effect, the action range of grounding distance protection will exceed and shorten, which brings many practical engineering problems to relay protection. The problem of exceeding and shortening the action range of the grounding distance protection can be better solve...

AI Technical Summary

Problems solved by technology

However, in engineering applications, for short-distance transmission lines or high-voltage especially ultra-high-voltage lines, due to technical and economic considerations, the line is often not completely transposed. At this time, the measured impedance of the protection is not only affected by the zero-sequence mutual inductance, but also Also affected by positive-sequence mutual inductance and negative-sequence mutual inductance, the distance element will show some complex characteristics after zero-sequence compensation, and its distance protection range will show obvious shortening and surpassing when different phases fail, which is difficult to meet the high voltage The backup protection requirement of the double-circuit line on the same tower without transposition in the large power grid has laid a great potential safety hazard for the safe and stable operation of the power grid

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