De-noising for partial discharge signals of power transformers using wavelet threshold method based on ant colony optimization

This paper presents an improved method of ant colony optimization wavelet threshold for partial discharge (PD) signals de-noising. A thresholding function with continuous derivatives based on the ant colony optimization algorithm is utilized for the threshold calculation. The ant colony optimization algorithm is competent to obtain the global optimum thresholds and to raise the efficiency of adaptive searching computation. De-noising experiments of simulative PD high frequency signals and detected PD ultra-high frequency signals with two methods were presented. The results show that the waveform distortion and magnitude errors of the de-noised signals by the proposed method are smaller than those by the soft threshold calculation method.