Experimental study on UHF pattern of partial discharges in transformer bushings

As busing fault is a serious problem, the traditional method to detect it requires bushing tap grounding lines, but generally there are few in the worksite. In order to solve this problem, this paper proposes a bushing partial discharge detection and pattern recognition method based on ultra-high frequency technology. According to the typical defects in actual bushings, four PD defect models were designed on an 110kV transformer bushing. And then the PD signals of different defects were detected by pulse current method and UHF detection method through a set of experiments. The results show that: (1) the partial discharge defects of bushings UHF phase patterns and the results of pulse current method are basically identical; (2) the PD defect types and possible discharge position would be identified based on morphological characteristics of PRPD and NV maps. UHF method can be used to detection and identify partial discharges in transformer bushings. The research has a guiding significance on on-line bushing PD detection.