Research on Island Detection Based on Improved Positive Feedback Active Frequency Shift

Abstract

Island detection is the essential function of photovoltaic grid connected generation system. The detection of the island effect must be accurate and fast, and the effect of the island detection method should be minimized on the quality of grid connected current. The positive feedback active frequency drift method is the most widely used method in current application. Aiming at the shortcomings of the detection blind area and the affect of quality of grid connect current of the algorithm. An improved positive feedback active frequency drift method is proposed. By detecting the magnitude the frequency offset of the initial time, the method is applied to determine the initial chopping factor and the direction of the disturbance by detecting the frequency deviation of the initial size, and the absolute value of the cumulative frequency deviation as positive feedback effect act on the common point. The improved island detection method not only improves the detection accuracy, but also reduces the current harmonic distortion rate. The simulation results shows that the improved AFDPF algorithm island detection time is faster than traditional AFDPF algorithm 0.04 s.