Analysis and rejection of noises from partial discharge (PD) on-site testing environment

There were many kinds of interference resources in the partial discharge on-site testing environment for a power transformer. According to their spectrums, those could be classified into sinusoidal continuous noises from power carrier communication and radio systems, pulse-shaped wide-band noises including periodical and stochastical pulse-shaped noises, as well as the background noise which was similar to the white noise. Generally speaking, the sinusoidal continuous noise would "submerge" the partial discharge information of monitoring signals which should be suppressed firstly. Rejection methods for this kind of interference were mainly adaptive filters, FFT frequency-domain filtering, wavelet denosing and digital high-pass filters based on Remez algorithm etc. Results of on-site PD signals indicated that the digital high-pass digital filter based on Remez algorithm had optimum rejection effects and best signal-to-noise ratio.