Frequency-shift acceleration control for anti-islanding of a distributed-generation inverter

This paper proposes frequency-shift acceleration control for anti-islanding of an inverter-based distributed generator. The proposed control is based on frequency positive feedback in the synchronous $dq$ frame. Overall, the scheme of the proposed control is described. The design methodology of the frequency-shift acceleration gain is presented based on small-signal stability and step input response. The proposed control is intended for zero nondetection zone, noncompromised power quality, and easy implementation without additional devices required. Simulation and experimental results verify that the proposed anti-islanding scheme and the gain design approach are effective and useful in real applications.