Partial Discharge Experimental Study for Medium Voltage DC Cables

Medium voltage dc (MVDC) distribution is a promising solution for many applications such as transportation electrification, city centers, oil and gas platforms, and renewable energy collection systems. Compared to ac, a MVDC system can significantly improve power density, energy efficiency, and controllability. Weight and size of power equipment are limiting factors in transportation electrification, and cables usually take up a large space in a power system. A focus of this research is to investigate the potential of dc supply to reduce cable size without compromising cable service life. Since partial discharges (PD) in internal voids have been identified as a major source for power equipment premature failure, it is critical to understand PD mechanisms of medium voltage cables under both ac and dc, especially PD from internal void and delamination. This paper presents PD experimental data from medium voltage cables and test coupons to show that dc supply could be a more favorable condition for cables than ac.