SF6 가스중 부분방전펄스 분석에 의한 지능형 결함판별 알고리즘

Abstract

This thesis dealt with an intelligent algorithm for defects identification by the analysis of partial discharge(PD) pulses in gas insulated switchgear(GIS). Needle-plane electrode, plane-needle electrode, floating metal and crack inside spacer were fabricated to simulate the defects in GIS. Each electrode system was placed at the inside of shielding enclosure and a non-inductive resistor was installed between the electrode system and ground wire.

PD pulses were measured by an oscilloscope with the frequency bandwidth of 1GHz and the sampling rate of 5GS/s. And the data aquisition and signal processing were controlled by a LabVIEW program. Also, the digital filter was designed to eliminate a power frequency and external noise.

The parameters of a single PD pulse in relation with the polarity of power frequency were analyzed depending on defects. The physical shapes were compared by using kurtosis, skewness, and time-base parameters such as rising time, falling time, pulse-width, and maximum voltage. By applying the proposed algorithm, the identification rate were 97% in needle-plane electrode, 96% in plane-needle electrode, 91% in floating metal, and 93% in crack inside spacer. From the results, it was verified that the proposed algorithm can identify the type of defects in GIS.