Active anti-islanding method based on harmonic content detection from overmodulating inverters

This paper proposes a cost effective, simple, and effective method to prevent islanding of grid-connected inverters. It discusses the shortcomings of previous passive and active methods to prevent islanding of utility interactive inverters. A new method, in which the inverter interfacing the main grid and a microgrid is periodically operated in the over-modulation region is proposed. Islanding is detected by measuring the harmonics generated by the over-modulating inverter. It is shown that the proposed method overcomes disadvantages of previously suggested methods without increasing the implementation cost and complexity. Results are validated with the help of simulations and experiments.