The control strategies for microgrid converters in grid-connected mode and islanding mode are different. Without reliance on rapid communication
micro-grid converters must be able to distinguish the states of the microgrid system on their own. In consideration of the practical operation environment
a new composite islanding detection method combining positive feedback of uncharacteristic harmonics and passive islanding detection is proposed for microgrid converters based on the islanding detection idea of voltage positive feedback. The principle
coefficient values and measurement mode of positive feedback are analyzed
and the feasibility of the method proposed is verified by simulation and experimental study. The simulation and experiment results show that the proposed method can detect islanding quickly and accurately in complicated working environments. What is more
it is conducive to smooth changeover for microgrid converter control strategy.