Partial discharge recognition of insulation defects in HVDC GIS and a calibration approach

Partial discharge (PD) monitoring is an established technique used to assess the condition of AC gas insulated switchgears (GIS). The growing application of High Voltage Direct Current (HVDC) transmission systems has triggered research projects focusing on the measurement and interpretation of PD signals in DC GIS. In this paper, several insulation defects are characterized using Phase Resolved Partial Discharge (PRPD) patterns in HVAC. The defects then are identified using Time Resolved Partial Discharge (TRPD) patterns in HVDC. Noticeable characteristics of PD patterns in HVDC are presented and related with the physical phenomena of the discharges. The potentiality of on-line defect recognition based on Radio Frequency (RF) PD detection measurement is discussed. In addition, the relationship between the apparent charge and the frequency spectrum of the PD signal is investigated.