Improved active frequency drift anti-islanding method with lower total harmonic distortion

As more distributed generators join the utility grid, the concern of unintentional islanding increases. This concern is due to the safety hazards this phenomena imposes on the personnel and equipment. Passive anti-islanding methods monitor grid parameters to detect islanding, whereas active methods inject perturbation into current waveform to drive theses parameters out of limit. The performance of active methods, such as conventional active frequency drift method (AFD), is limited by the amount of total harmonic distortion (THD) they inject into the grid. In this paper a novel anti-islanding method is presented, which generates 30% less THD than the AFD, which results in faster island detection and better non-detection zone. The performance of the proposed method is derived analytically, simulated using MATLAB and verified experimentally using a prototype setup. A single phase grid-tied photovoltaic distributed generation system is used for the simulation and experimental setup, and considered as potential application.