FILTER FOR OPTIMAL TEMPORAL RESOLUTION IN PARTIAL DISCHARGE MEASUREMENTS.

Abstract

In partial discharge measuring instruments, a band-pass filter is always incorporated for noise reduction. There is a tradeoff between SNR and temporal resolution. The problem of optimizing the temporal resolution in the presence of noise is analyzed and a Wiener filter is proposed as the solution. Methods to implement the filter are given and results of computer evaluation studies are presented. This study shows that the Wiener filter is superior for both temporal and amplitude resolution, and especially for resolving overlapped discharges of opposite polarity. This is partly because the study was based on a completely determined impulse response function and an accurately known noise spectral density. It is noted that the superior performance demonstrated should be considered with some reservations. The disadvantage of the method is that the filter frequency response has to be adjusted for each different application, making the hardware and software more complicated.