Research on detection and recognition of partial discharge in gas insulated system

Partial discharge (PD) is one of the major factors causing insulation damage of gas insulated system (GIS). The conventional PD detection methods are too susceptible to disturbances and unsuitable for on-line monitoring. The ultra-high-frequency (UHF) PD detection technique can detect and locate the PD sources inside GIS by detecting electromagnetic wave emitted from PD source. The narrow band UHF method was emphasized in this paper, because it can avoid the electromagnetic interference by selecting the appropriate frequency. A PD detection system using narrow band UHF method was designed. The typical defects that can cause partial discharge in GIS were simulated in laboratory. Using this detection system the PD waveform of frequency domain and time domain could be gotten. The results show that the time domain waveforms of the same defect have very similar distribution characteristics and those of different defect have different ones. So it would be very convenient for the recognition of PD types.