Simulation on locating partial discharge in T-shaped branch of GIS by applying the STA/LTA ratio method to EM waves leaked from insulating spacers

This paper describes partial discharge (PD) location through electromagnetic (EM) waves in ultra-high frequency (UHF: 300MHz-3GHz) band leaked from the insulating spacers in a T-shaped branch of gas insulated switchgear (GIS). The propagation of EM waves in GIS and the leakage through spacers were simulated by using the finite difference time domain (FDTD) method. The time difference of arrival (TDOA) of leaked EM waves was employed to locate PD under white noise background. The short-term-average to long-term-average (STA/LTA) ratio method was applied to estimate TDOAs among the monitoring points arranged on the circumference of the insulating spacers in a connection of the next section of GIS. The simulation results showed that PD position could be located through the EM waves leaked from spacers of GIS wherever PD in a T-branch or straight section. The average location error of PD in the T-branch was larger than that of PD in the straight section. The PD positions and pairing of monitoring points had little influence on the location accuracy. Finally, the influence of flanges and bolts on PD location was investigated.