Analysis on partial discharge propagation and detection in MV power transformers

UHF Partial discharge (PD) detection in MV transformers is discussed in this paper. Transformers are modeled as resonant cavities and bushing openings as slot antennas. Laboratory tests are carried out to validate the models. At first, irradiation properties are determined placing emitting dipoles inside a dummy transformer tank and detecting the electromagnetic emission through appropriate antennas. Then, CAD simulations are done showing good fitting with experimental results. At last, simulations and PD measurements are carried out on a three-phase 15 kV transformer in order to find the optimum detection bandwidth and develop suitable PD sensors.