A distance protection method for double-circuit lines on the same tower without transposition

Abstract

The invention discloses a distance protection method for a double-circuit line without transposition on the same tower. First, based on the existing fault phase selection method, the fault phase of the double-circuit line without transposition on the same tower is accurately identified; secondly, using the actual The six-phase impedance matrix that tower structure obtains calculates average self-impedance, phase-to-phase mutual impedance, line-to-line mutual impedance and virtual line positive-sequence impedance and zero-sequence impedance; Fault calculation is carried out, and the protection area of ​​each fault phase is set separately; the method of the present invention can make the distance protection of the double circuit line without transposition on the same tower work in an excellent state and has important practicality for ensuring the safe and stable operation of the power system significance.

Description

technical field [0001] The invention belongs to the field of electric power systems, relates to the technical field of relay protection of double-circuit lines on the same tower without transposition, and in particular relates to a distance protection method for double-circuit lines on the same tower without transposition. Background technique [0002] At present, the double-circuit line on the same tower has been widely used in high-voltage power grids, and distance protection, as one of the mainstream backup protections of the line, plays an extremely important role in the safe operation of the double-circuit line on the same tower. There is zero-sequence mutual inductance between the ideally transposed double-circuit lines on the same tower. Under this action, the action range of the grounding distance protection will be exceeded and shortened, which brings many practical engineering problems to the relay protection. By introducing the zero-sequence current compensation o...

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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