Complex adaptive notch filters for frequency estimation of three-phase power systems

This paper presents a new technique for adaptive estimation of the frequency of unbalanced three-phase power systems using complex coefficient first-order notch filters. The input complex sinusoid is given by a sum of sequences with positive and negative frequencies. The analytical expression of a estimation error oscillation introduced by the sequence with negative frequency has been derived. Closed form expression for frequency tracking error has been also derived for a complex linear chirp signal. Computer simulation results are presented to validate the analysis.