Application of adaptive filters for the estimation of partial discharge signals in noisy environments

Partial discharges are localised "electrical sparks" involving the flow of electrons and ions when a small volume of gas breaks down. This can occur in voids within the electrical insulation system itself or adjacent to the insulation of high voltage equipment. The progressive development of partial discharge activity is the major symptom of insulation deterioration. Unfortunately the PD (Partial Discharge) signals usually are superposed by various continuous or pulse shaped interferences (ambient noises, corona discharges, high frequency harmonics, etc.). An adaptive filter is a powerful tool in digital signal processing and can be used for estimation of a desirable random signal in the presence of an additive random noise. By means of an adaptive noise cancelling algorithm one can improve signal-to-noise ratio (SNR) of measured Partial Discharge signals in an unknown environment, resulting in a better system performance compared to direct filtering of the received signal. In fact the adaptive filter minimises the power of the noise at the output of the system while maintaining the desired signal almost unaffected.