Statistical operators calculation of partial discharge on floating electrode defect in GIS

This paper considers the features extraction of Gas Insulated metal-enclosed switchgear(GIS) which suffer from partial discharge (PD) by floating electrode defect. The 220 kV GIS bus bar cavity is taken as an object to design physical model of floating electrode defect. The experiment PD data are obtained from a 220 kV GIS equipment using Ultra-high frequency(UHF) partial discharge measurement. The data is stored as phase resolved pulse sequence (PRPS) data format. This data format allows the actual test voltage (rms) of every cycle, the number of measuring cycles, phase information of all PD pulses, together with their peak values to be obtained, so the discussion of statistical analysis of the floating electrode defect can be performed. Firstly, the phase resolved partial discharge (PRPD) pattern is calculated from the PRPS data sets. Then, the statistical operators at different voltage levels are extracted from the PRPD patterns of the floating electrode defect. On the basis of the present experimental research and statistical analysis, statistical operators such as skewness, kurtosis can be used to classify different PD defects.

I. Introduction

Gas Insulated metal-enclosed switchgear (GIS) has been widely used in high-voltage power system. On the basis of the CIGRE 23.10 investigation report, insulation fault is the main cause of the accident in GIS. If any insulation faultexists inside GIS, the intensity of the electric field around the insulation fault increases locally. In this case, it will cause a partial discharge (PD), progressive deterioration and, in the worst case, an insulation breakdown. Therefore, the PD detection is considered an effective way to avoid insulation failure and identify insulation defects in GIS [1]–[4].