Islanding control for grid-connected inverters

Non-detection zone disables the conventional islanding protection.In order to solve the problem,a novel control solution based on the frequency positive feedback disturbance is proposed to achieve the effective islanding protection.Considering high power applications,it is not practical to apply the islanding protection control any more.Therefore,the concept of controlled islanding is proposed in IEEE Std.1547-200.This paper presents a novel controlled islanding based on the operation mode transfer,which maintains the voltage to keep critical loads in safe operation.The proposed islanding control solutions are verified by the simulation results.