The feasibility of locating PD source in transformer using the UHF technology

Lots of researches have demonstrated that the UHF technique is an effective way for on-line partial discharge monitoring in power transformers. According to the shortest optical path principle, it is possible to locate the PD source by time-of-flight analysis of the incident UHF signals by multiple sensors, but it is still left unknown because of the complex structure of power transformers. In this paper, the feasibility of locating the PD source using UHF is studied based on experiments on simple propagation models using basic geometrical conducting obstacles. We found that large conducting obstacles could bring errors or even make fault location impossible due to its shielding of EM waves. When an aperture was put in conducting obstacles, to simulate the oil gap in transformers, the results changed a lot. Based on the experimental results, the relationship of the time-of-flight and the propagation path was studied; the validity and effective scope of the shortest optical path principle was discussed.