Time-to-Arrival Estimation of UHF PD Signals Based on Dynamic Cumulative Sum of Likelihood Ratio

Estimation of arrival time of EM waves emitted from Partial Discharge (PD) source to the probes is one of the most important parts of PD localization in ultra-high frequency (UHF) range in power transformers. Even a small error in estimation of the start point of PD pulses leads to inaccurate results in PD localization. In this paper a method based on dynamic cumulative sum (DCS) of the normal distribution likelihood ratio is used and compared with more common methods of arrival time estimation including discrete wavelet transform (DWT), the energy accumulation and the average time window methods. These four methods are applied on simulated and laboratory measured signals. High accuracy and robustness against noise are two important features of the proposed method.