Digital protection systems rely on accurate phasor estimation. When a fault occurs in such systems, fault current contains non-fundamental frequency components and DC component in addition to the fundamental frequency component. A DC component has a significant impact on the performance of the Fourier filter. A lot of different algorithms have been proposed in the past in order to eliminate this component. In this paper, we present a comparative analysis of the selected algorithms. Furthermore, we propose a new algorithm which combines different approaches and exploits their advantages. A performance evaluation of these algorithms is done by using a simple power system network model. Finally, the selected algorithms are compared using following criteria: the speed of convergence of the Fourier algorithm, the impact of non-fundamental frequency components, the impact of off-nominal frequency and computation burden. Our results have shown that the proposed algorithm outperforms previously proposed algorithms under a variety of negative effects encountered in a real power system.
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