Partial discharge diagnosis for transformer — One step toward strong smart grid in China

This paper presented four cases of online/offline partial discharge (PD) diagnosis in various scenarios. Some case gave strong evidence of PD occurrence but no discharge signal was detected. Some case gave obvious PD signal pattern, which was identified as noise. In the last case, a small PD phenomenon was identified and located by a combination of several diagnostic methods, including dissolved gas analysis, leakage current analysis, and PD detection through pulse current signal and ultra sonic signal. The results show that online PD detection was useful but complicate. The information can be conflicting and misleading. A comprehensive understanding of test condition and an in-deep study of the measurement results is essential in such diagnosis.