Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title Improved Phase and Harmonic Detection Scheme using Fast Fourier Transform with Minimum Sampling Data under Distorted Grid Voltage
Authors Hyun-Sou Kim, Kyeong-Hwa Kim ;
DOI 10.6113/TKPE/2015.20.1.72
Page pp.72-80
ISSN 1229-2214
Keywords Distorted grid; FFT(Fast Fourier Transform); Minimum sampling; PLL(Phase Locked Loop)
Abstract In distributed generation systems, a grid-connected inverter should operate with synchronization to grid voltage. Considering that synchronization requires the phase angle of grid voltage, a phase locked loop (PLL) scheme is often used. The synchronous reference frame phase locked loop (SRF-PLL) is generally known to provide reasonable performance under ideal grid voltage. However, this scheme indicates performance degradation under the harmonic distorted or unbalanced grid voltage condition. To overcome this limitation, this paper proposes a phase and harmonic detection method of grid voltage using fast Fourier transform (FFT). To reduce the calculation time of FFT algorithm, minimum sampling data is taken from the voltage measurement to determine the phase angle and the magnitude of harmonic components. An experimental test setup for a grid-connected inverter system has been constructed. By comparative simulations and experiments under various abnormal grid voltage conditions, the proposed scheme has been proven to effectively track the phase angle of the grid voltage.