Study of wavelet-based threshold de-noising for power quality signal

Signal denoising is an important problem in the field of power quality (PQ) diagnosis of power system. Because the wavelet coefficients of noises are trending towards zero rapidly follow the scale increasing, the denoising methods based on wavelet transform have been widely applied. Threshold denoising method based on wavelet transform is an efficient method to reduce the white noise in the digital signal. There are two key problems need to be solved in practice. One is the optimization of the threshold; another is the determination of the decomposition order. This paper overviewed the theory of basis wavelet-based threshold denoising method and some kind improved soft-threshold theory, summarized their applications in the area of power quality signal denoising. All of results show wavelet-based threshold denoising method has great potential for PQ signals denoising. The analysis direction and emphasis of studying about the power quality (PQ) signal de-noising also put forward.