Effect of Voltage Slew Rate on Partial Discharge Phenomenology during Voltage Transient in HVDC Insulation: The Case of Polymeric Cables

In this article, the partial discharge (PD) behavior inside a cavity embedded in a dc cable, upon application of a voltage step from transient till steady-state dc, is analyzed as a function of voltage slew rate. The variation of PD characteristics, namely PD charge amplitude and repetition rate, is modeled and fitted from the beginning of the voltage transient to dc steady state, and the extent of aging associated with PD at different slew rates is evaluated through a cumulative damage concept. Two possible scenarios for the electric field transient and PD repetition rate are presented, differing for the ratio of conductivity and permittivity of dielectric and cavity medium. Having demonstrated that the proposed PD repetition rate model can predict reasonably the experimental results, it is shown that slowing down voltage rise time during, e.g., cable energization or voltage polarity inversion, could be beneficial to reduce the accelerated aging extent associated with voltage transients.