Detection in Spacer of Gas-Insulated Switchgears

With the increasing demand for precise condition monitoring and diagnosis of 11 gas-insulated switchgears (GIS), it has become a challenge to improve the detection sensitivity of 12 partial discharge (PD) induced in the GIS spacer. This paper deals with the elimination of the 13 capacitive component from the phase resolved partial discharge (PRPD) signal generated in GIS 14 spacer based on the discrete wavelet transform. Three types of typical insulation defects were 15 simulated using PD cells. The single PD pulses were detected and were further used to determine 16 the optimal mother wavelet. As a result, the bior6.8 was selected to decompose the PD signal into 8 17 levels and the signal energy at each level was calculated. The decomposed components related 18 with capacitive disturbance were discarded whereas those associated with PD were de-noised by a 19 threshold and a thresholding function. Finally, the PRPD signals were reconstructed using the 20 de-noised components. 21