Study on propagation characteristics of partial discharge-induced UHF signal in GIS with L shaped structure

Detecting the partial discharge (PD) phenomenon in gas insulated switchgear (GIS) by using ultra-high-frequency (UHF) method is an effective diagnosis method to avoid insulation accidents. Practically, UHF sensor will receive various signal components due to different placements and installation locations, which can greatly influence the diagnostic analysis result. Thus, in order to deeply understand the propagation process of electromagnetic (EM) wave and develop the utilization of the UHF method, it is necessary to investigate the attenuation process of EM wave in each circumferential angle and direction. In this research, the propagation characteristics of UHF signals in the GIS model with L shaped structure is analyzed thoroughly by using finite difference time domain (FDTD) method. Comparing the results in straight GIS tank, the influence of L shaped structure to the attenuation of PD signals in different circumferential angles and directions is mainly analyzed. And the propagation rules of the peak to peak value (Vpp) and cumulative energy of the coupled voltage in each case are summarized. This paper elucidates the propagation mechanism of EM wave in L shaped tank and lays a foundation for the rational use of UHF sensor and better conduct of PD detection.