A new method based on wavelet packet transformation to reduce narrow band noise in on-site PD measurement

The suppression of interference is crucial in onsite Partial Discharge (PD) monitoring. This paper presents a new algorithm to reduce narrow band noise coupled into PD measurements. The algorithm is based on wavelet packet analysis and is capable of automatically detecting narrow band interference without requiring prior knowledge of detailed noise characteristics. Simulations are provided as well as some results obtained during laboratory experiment and on-line PD measurements for a power transformer. The efficiency of reducing narrow band noises is measured by comparing the frequency spectrum before and after filtering with the new method.