Elimination of DC offset in accurate phasor estimation using recursive wavelet transform

DC offset has significant effect on extracting fundamental frequency components. It directly impacts the accuracy of the fundamental frequency component based protective relaying algorithms. This paper proposes a novel method for estimating the fundamental phasor while eliminating the DC offset using improved recursive wavelet transform. The proposed approach converges to the actual value in less than one cycle, and the computation burden is fairly low because of the recursive formula. Studies indicate that to achieve a certain level of accuracy, the higher sampling frequency one uses, the shorter data window the computation needs, and vice versa. Comparing with conventional DFT filter, simulation results demonstrate that the proposed phasor estimation method achieves better performance.