Selective generator stator single phase grounding protective method

Abstract

A selective protection method for single-phase earthing of generator stator uses three times of B-spline wavelet as an analysing tool to directly analyse the measured voltage at two sides of generator end and neutral point as well as zero sequence current, and it can be sure that 100% of earthing fault of generator stator can be identified reliably by this method which works as using standard connection form for voltage and current mutual-inductor, calibrating the phase of zero sequence current at generator end, using mode maximum value as a start element after zero sequence voltage being analysed by B-spline wavelet, to judge whether the earthing fault of internal single plase of generator stator is produced or not by checking that the mode maximum value of zero sequence current at generator end and zero sequence voltage of generator end and neutral point side is in an uniformity or not through the analysis by B-spline wavelet.

Description

technical field

[0001] The invention relates to a generator stator single-phase ground protection method, in particular to a selective generator stator single-phase ground protection method, which belongs to the field of relay protection. Background technique

[0002] The single-phase grounding of the stator of the generator is often a harbinger of a phase-to-phase or inter-turn short circuit, so the stator grounding protection is of great significance. According to literature search, Huang Shaofeng and others published "Generator Stator Grounding Protection Based on the Principle of Third Harmonic Phase Angle Sudden Change" in "Power Grid Technology" No. 12, 2000. The 100% stator grounding protection scheme composed of the third harmonic of the generator and the fundamental zero-sequence voltage has been widely used at home and abroad. The fundamental zero-sequence voltage protection can realize the protection of 85% to 95% of the stator winding. It is used together with t...