Wavelet analysis of partial discharge acoustic signals in a model transformer

The focus of acoustic partial discharge measurements is based on the discharge location. The tank wall thickness of a power transformer is usually larger than the wavelength of the signal, and therefore possesses a path for the signal, thereby complicating the triangulation procedure for the determination of the discharge location. Owing to their difference in frequency, the signals that travel faster through the mixed path of oil and tank and the slower ones that follow a direct path through oil can be differentiated. By using wavelet transform, we are able to not only discriminate between these two signals, but also to determine the exact instant at which a change in the detected signal occurs due to their interference. This is a new method of analyzing the partial discharge acoustic signal to extract the signal that travels through the direct path in oil and can lead to a more accurate discharge location.