analyzing the relationship between uhf partial discharge signal features and transferred charge

The ultra-high frequency (uhf) technique offers significant advantages over the conventional partial discharge (pd) measurement method, particularly for online monitoring, 3d localization, and immunity against noise. however, its primary limitation lies in the challenge of calibration due to the impact of various factors such as pd source locations, antenna characteristics, and transformer structures including, active part and tank wall, on the received uhf signals. currently established parameters such as signals peak-to-peak and energy of signals do not provide a meaningful correlation between received uhf signals strength and factors such as distance and antenna radiation pattern. addressing these gaps, this paper introduces a novel parameter: the first arrived signal (fas), derived from the short-time fourier transform (stft) of uhf signals. experimental results demonstrated the capability of the fas to correlate meaningfully between signal strength and distance from the source, as well as antenna radiation pattern and polarization. the proposed parameter is then utilized to estimate conventional transferred charge using the received uhf signals. results indicate promising estimation accuracy, particularly when electromagnetic waves directly reach the antenna. this approach offers the potential for a more precise estimation of conventional pd transferred charge, enhancing the capabilities of the uhf method in assessing insulation system health conditions.