Wavelet-based denoising for PD online measurement of transformers

The method based on thresholding and shrinking empirical wavelet coefficients is introduced in this paper for denoising PD signals. Because the wavelet-based denoising can not give a satisfied results while PD pulse amplitude is the same as or less than that of discrete spectral interferences (DSI), the wavelet combined with 2nd order lattice infinite impulse response (IIR) notch filter is proposed to enhance the signal-to-noise ratio (SNR) of signal detected by PD online measurement system of transformers. We present the results from simulations and real data examples.