Transformer backup protection method in six-phase transmission system

Abstract

The invention relates to a transformer backup protection method in a six-phase power transmission system. The method comprises the steps that two sets of three-phase currents on the side of a transformer three-phase system are collected, and the amplitude of same positive sequence currents, the amplitude of same negative sequence currents and the amplitude of reverse positive sequence currents are respectively calculated through a six-sequence component method (please see the specification for the expression); the same positive sequence currents are used for judging a six-phase short circuit, when the amplitude of the same positive sequence currents is larger than a setting value IT1.op, protection action is performed, the setting value is set according to the maximum same positive sequence current, namely a load current IN during normal operation; the same negative sequence currents and the reverse positive sequence currents are used for judging all the interphase short circuits except the six-phase short circuit, when the amplitude of the same negative sequence currents or the amplitude of the reverse positive sequence currents is larger than a setting value IT2.op or IF1.op, protective action is performed, the setting value IT2.op and the setting value IF1.op are set according to the maximum same negative sequence unbalanced current and the maximum reverse positive sequence unbalanced current during normal operation, and three current protection OR gates are used for outputting. The transformer backup protection method in the six-phase power transmission system has the advantages of being higher in protection sensitivity and easy to implement.

Description

technical field [0001] The invention relates to the field of six-phase power transmission and relay protection, a new power transmission mode of a power system, and in particular to a transformer backup protection method applied in a six-phase power transmission system. Background technique [0002] Six-phase power transmission has huge economic and environmental benefits. It can not only increase the natural power of line transmission, reduce the area occupied by line corridors, but also suppress the occurrence of corona and reduce radio interference. It is an important development direction of EHV transmission [1]. attached figure 1 It is a typical six-phase transmission system, which consists of four transformers and six-phase transmission lines. The parallel three-phase system is converted into a six-phase system through two transformers, and the six-phase system is converted into a parallel three-phase system through two transformers at the other end. phase system. Th...

AI Technical Summary

Problems solved by technology

This means: if the transformer in the six-phase system still adopts the same traditional backup protection as the three-phase transformer, its sensitivity as the backup of the transformer itself and the remote backup of the six-phase transmission line will be greatly reduced, and it is very likely that it will not meet the sensitivity requirements

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