Iterative Interpolated DFT-based Frequency Estimator for Electrical Waveform Affected by Decaying DC Offset

Abstract

An iterative Interpolated Discrete Fourier Transform (IpDFT)-based frequency estimator of a sinewave affected by decaying dc offset is proposed in this paper. The accuracies of the proposed procedure and the classical IpDFT algorithm are compared with each other under different steady-state and dynamic testing conditions suggested in the IEC/IEEE 60255-118.1:2018 - Synchrophasors for power systems – Measurements. A decaying dc offset is added to the test signals suggested in the Standard and off-nominal frequency is considered. Procedure accuracy is analyzed through simulations by considering the maximum of the absolute value of the frequency error. Comparison with the frequency error thresholds proposed in the Standard is also performed.