Analysis of current-controller in grid-connected and islanded mode for dispersed generation

An islanding is that the islanded entity including DGs and critical load disconnects from the utility and then, operates in the islanded mode. During that mode, the Power Electronic Interface of DGs not only has a role in keeping the Point of Common Coupling´s voltage within a required range, it also needs to make islanded frequency arbitrarily at normal values. This paper investigates the operation response while keeping the conventional current controller in some cases of typical islanded loads and then, validate feasibility of proposed current controller for the islanded entity dealing with transient-to-island mode. The islanding detection method by using negative-sequence impedances also facilitates the fast switching for the entire control scheme. The droop control mechanism is presented for inductive-reductive impedance.