Abstract
In electrical engineering, it is of great importance to monitor partial discharge (PD) of high voltage apparatus. However, on-site PD signal easily gets corrupted by white noise, and hence denoising the measured PD signal is necessary to acquire pure PD. In traditional method, single wavelet and regular thresholding are utilized. By combining wavelets of the same family, dual-tree complex wavelet pairs can be constructed. Specific combinations are approximately translation invariant, and they are also able to achieve better denoising effect without sophisticated computation. Meanwhile, considering the correlation between adjacent wavelet coefficients, the block thresholding is employed. In this paper, it is proposed to combine wavelet pair and block thresholding for PD denoising. There are four combinations based on single wavelet/wavelet pair and regular thresholding/block thresholding, and they are compared with each other. Based on a numerical study, the results demonstrate that the proposed algorithm outperforms the traditional method.
Highlights
In power system, partial discharge (PD) is one of the most common factors damaging the insulation of high voltage apparatus
CASE STUDY OF NOISY PD DENOISING the mathematical models of four typical PD signals described in [35] are adopted, i.e. the ultra high frequency (UHF) PD signal in gas insulated switchgear (GIS) with sulfur hexafluoride (SF6) as the medium
The results show that among four combinations, the proposed wavelet pair/block thresholding performs best
Summary
Partial discharge (PD) is one of the most common factors damaging the insulation of high voltage apparatus. S. Zhou et al.: PD Signal Denoising Based on Wavelet Pair and Block Thresholding for a translation invariant complex wavelet, the scale filter hr of its real part and the scale filter hi of its imaginary part should satisfy 1/2 sample point delay condition [17], [18], i.e. hi(n) = hr(n−0.5). To keep approximate translation invariance as possible, Kingsbury and Selesnick et al [16], [19], [20] pointed out that it is necessary to construct a dual-tree complex wavelet and use two individual wavelets to denoise the signal. In order to achieve better PD signal denoising results, it is proposed to combine wavelet pair and block thresholding in this paper.
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