A High-Precision Algorithm for Phasor Measurement Based on DFT
WANG Chao, WANG Fang-zong (College of Electrical Engineering & Information Technology, China Three Georges University, Yichang 443002, Hubei, China)
A new phasor measurement approach based on conventional DFT algorithm has been proposed. Firstly, with the fundamental signal, the equation of frequency deviation can be obtained by using of data derived from DFT of two data windows in the proposed approach. Hence, the accurate frequency, amplitude and phase of fundamental signal can be obtained after solving this equation, and there is no any approximate error in the process of derivation of the proposed approach in which the operation amount can be effectively reduced and the measurement accuracy is improved. Then, in order to improve the measurement accuracy with harmonics, it is applied by counteracting the spectrum leakage of data derived from DFT of two data windows which stagger about half period of signal, the same algorithm of measure phasor, tracking of sampling frequency, and measuring again. Finally, signals with harmonics and noises are simulated respectively, and the results show high accuracy of this algorithm in all these situations.