Wavelets Selection for Commutation Failure Detection in HVDC System

This paper presents a wavelet based commutation failure (CF) detection technique in HVDC system, and selects the suitable mother wavelet. The different properties of wavelets are analyzed in detail. It is shown that the orthogonality, regularity, moments, and symmetry of a wavelet function may affect the CF detection to some extent, and the critical factor is the moments of the mother wavelet. Discrete wavelet transform (DWT) has executed respectively on normal sinusoidal voltage signal and alternative voltage record with CF in Tianguang HVDC project. The transform result shows that DWT by Daubechies wavelet function with high vanishing moments is a cogent tool for CF detection in HVDC system