A zero-sequence current protection method and system

Abstract

The invention provides a zero-sequence current protection method and system. The method includes: calculating the zero-sequence current of a first line and a second line of a three-circuit line on the same tower whose two ends share a bus; building a three-circuit line on the same tower based on an EMTP simulation model The actual model of the loop line is used to calculate the zero-sequence circulating current coefficients of the first line and the second line, respectively; Zero-sequence current of the line; according to the zero-sequence current of the first line and the second line and the compensated zero-sequence current of the first line and the second line, it is determined whether the zero-sequence protection action is required. The zero-sequence current protection method provided by the invention is accurate and effective, conforms to the actual project, and effectively avoids the malfunction of the zero-sequence current protection of the line.

Description

Technical field: [0001] The invention belongs to the field of power system relay protection, and in particular relates to a zero-sequence current protection method and system. Background technique: [0002] In order to cope with problems such as the tense situation of power supply and the reduction of power transmission corridors, the construction conditions of power transmission network are becoming more and more complicated. The application is continuously realized in the ultra-high pressure system. [0003] However, the complicated line erection method leads to the asymmetry of the three-phase parameters of the line. When the line is in normal operation and fault, the unbalanced line parameters will directly lead to the appearance of unbalanced current in the line. In order to limit the unbalanced current caused by electromagnetic coupling, it is stipulated in our country that lines with a length of more than 100km in the ultra-high voltage power grid should be transpos...

AI Technical Summary

Problems solved by technology

In this case, since the zero-sequence current protection method of the first and second double-circuit lines does not take into account the influence of adjacent lines, it is easy to cause zero-sequence current protection due to the large zero-sequence circulating current of the double-circuit line due to the mutual inductance of the third circuit line. Misoperation

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