A Novel Power Frequency Phasor Algorithm for Non-uniform Sampling

The accurate and stable calculation of power frequency phasors is of vital significance to the safety and reliability of relay protection. The Fourier algorithm can calculate the power frequency phasor of a target signal using uniformly sampled discrete arrays. However, when there is jitter or variation in the sampling interval, it fails to accurately compute the power frequency phasor. This paper proposes a novel power-frequency phasor algorithm under non-uniform sampling conditions, achieving accurate phasor calculation amidst real-time variations in sampling intervals. The study begins by analyzing the frequency characteristics of conventional Fourier algorithms and examining their performance in processing non-uniformly sampled signals. Subsequently, by incorporating sampling time offset information and employing a fixed-point compensation approach, an improved Fourier algorithm adapted to non-uniform sampling is developed. Simulation results validate the effectiveness of the proposed algorithm. The proposed method can still obtain accurate calculation results even when the sampling cycle jitter is uniform, and fully effective even when handling real-time, point-by-point variations in sampling intervals, demonstrating substantial engineering applicability.