Partial Discharge Tests in DC Applications: A Review

The wide spreading of solar power generation stations, far off-shore wind farms, electric vehicles charging stations, as well as the high voltage DC power transmission systems has dramatically increased the development of DC power grid, which in turn calls new challenges to the partial discharge (PD) detections under DC voltage (DC-PD). Although PD diagnosis has been well studied and under industrial practice for decades, the experiences in AC-PD tests cannot be directly transplanted in the DC-PD applications. The mechanism of the initiation and recurrence of DC-PD differs from the situation under AC voltage. The testing and analyzing of DC-PD confront various challenges which are not presented in the AC applications. In the recent decades, more and more researchers have been focusing in the field of utilizing DC-PD diagnosis to verify the insulation design and to evaluate the dielectric deterioration under DC voltages. This paper gives a brief review of the published studies on DC-PD diagnosis. The review covers the PD signal generation, detection and data processing under DC voltages.