Advanced phase angle detection algorithm based on optimized half period fast fourier transform under harmonic distortion in grid voltage

Detecting the phase angle of the grid voltage is necessary in various applications which require grid synchronization. Presence of the harmonics or imbalance in the grid voltage causes errors in the detected phase angle and frequency, which lead to the distortion in inverter currents. To enhance the performance of the phase detection algorithm in distributed generation (DG) systems, such phase detection error needs to be removed. In this paper, a new phase angle detection algorithm based on the optimized half period fast Fourier transform (FFT) is presented. Using the half period symmetry of the grid voltage, the proposed algorithm processes only the last half periodic data of the measured grid voltage to obtain the phase angle information. Optimization of the sampling rates for FFT algorithm is done to minimize the calculation time. The proposed algorithm has robustness against the distortion of the grid voltage such as the harmonics or imbalance.