Frequency estimation using signal reconstruction approach

Abstract

Frequency estimated throughout the wide-spread grid is used for monitoring and controlling various local as well as global power system phenomena. Such applications require precise frequency estimation, especially during challenging power system conditions when signals are non-stationary or contain harmonics. Therefore, in this paper, a signal-reconstruction-based approach has been described to estimate the frequency and rate-of-change of frequency (ROCOF) for a single-phase system. The approach is based on the idea that the frequency information in case of a reconstructed signal is preserved even during off-nominal frequency conditions. Single-phase reconstructed time-domain signals are proposed as an alternative to phase-angle signals for frequency estimation. From the reconstructed time-domain signals, the frequency is estimated using the convolution average filter (CAF) based method and a single-phase demodulation technique employing Hilbert filter (HFD). The effectiveness of this approach especially during off-nominal and inter-harmonic conditions is demonstrated using the synchrophasor standard based test signals. The proposed method is compared against state-of the art single-phase phasor measurement unit based estimates. Accuracy of the reconstruction-based approach is also verified through signals obtained from the ISO-New England power system and simulation based studies. The output frequency and ROCOF signals are also used for mode identification using the Prony method. © 2023 Elsevier B.V.