Two-Stages Sliding Fourier Transform for High Performance Phase Angle and Frequency Tracking

다국어 초록 (Multilingual Abstract)

Sliding discrete Fourier transform (SDFT) gives excellent performance at nominal frequency operation. However, at off - nominal frequency, it generates errors in both magnitude and phase angle due to spectral leakage. Moreover, its harmonic rejection ability is greatly impaired in this case. This paper introduces a method to apply sliding Fourier transform under off -nominal frequency at fi xed sampling rate while fi xing the defects associated with it off -nominal frequency operation. This method involves the use of two stages sliding Fourier transform (SFT). A fi xed window-width SFT in the fi rst stage is used to drive the variable window-width SFT in the second stage. The proposed technique (SFT–SFT) is tested in real time on dSPACE MicroLabBox using pre-generated voltage vectors to simulate the most inconvenient grid conditions. The testing scenarios proved its superior performance compared to the decoupled stationary reference frame PLL method.

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