Ladder-Wise calculation method for z-coordinate of transformer PD source based on planar layout UHF antenna sensors

In locating a transformer partial discharge (PD) source, there is a large fluctuation error in the z-coordinate of the location, which results with planar layout ultrahigh-frequency (UHF) antenna sensors. For the large fluctuation error, this paper first theoretically analyzes the reason. According to the theoretical analysis results, a ladder-wise calculation method of the PD source z-coordinate is proposed: first, the x- and y-coordinates of the PD source are calculated, then the univariate equation f(z) is derived, and the z-coordinate of the PD source is obtained by f(z). Finally, the positioning effect of the ladder-wise calculation method for PD source z-coordinate is verified experimentally. Experimental results show that the proposed method can reduce the fluctuation of the z-coordinate of the PD source from 0.6 to 0.2, and when the PD location sample set is >= 10, the average absolute error of the z-coordinate is reduced from about 0.4 m to less than 0.1 m. (c) 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.