Analysis on Recursive Discrete Fourier Transform FLL Based on Delayed Signal Cancellation-PLL Method under Frequency Variations

In this paper, RDFT(Recursive Discrete Fourier Transform) FLL(Frequency Locked Loop) based on DSC-PLL(Delayed Signal Cancellation Phase Locked Loop) is proposed for coping with frequency variation. This method shows significant performance for detection of fundamental positive sequence component voltage when the grid voltage is polluted by grid harmonics and frequency variation. The frequency tracking technique of DSC-PLL is tracking the drift in the phase by the RDFT and TEO(Teager Energy Operator) concept. The proposed RDFT-FLL based on DSC PLL is to present the analysis on method and performance under frequency variations. These compensation algorithms can correct for discrepancies of changing the frequency within maximum 35ms and improve traditional DSC-PLL.