A Cable Partial Discharge Model with Consideration of Temperature and Working Voltage

Cable assets play a key role in power transmission and distribution. Partial Discharge (PD) is a very good predictor of cable insulation condition because most cable insulation failures can result in PD. Based on the analysis of PD results, it is found that temperature, which is relevant to load current and ambient temperature, and working voltage can influence the PD activities. However, previously published PD models failed to reflect the relationships among PD magnitude, PD numbers, the ambient operating temperature and working voltage. In this paper, the previously reported PD models are reviewed first. Then an improved PD model with consideration of load current, ambient temperature and applied voltage is developed. Simulation studies which is presented in the paper demonstrate how the PD magnitude responds to cable load current and ambient temperature. The voltage drop within a normal 10% limit due to cable impedance will have a negligible influence on PD magnitude. However, when a single phase-to-ground fault occurs, or the working voltage becomes 1.73 times higher, a 7% increase in PD magnitude is observed.