Control schemes for intentional islanding operation of distributed generation

Intentional islanding describes the condition in which a micro grid or a portion of the power grid, which consists of a local load and a distributed generation(DG) system, is isolated from the remainder of the utility system. In this situation, it is important for the micro grid to continue to provide adequate power to the load. The DG unit utilizes a voltage sourced converter (VSC) as the coupling medium. In a grid connected mode, based on the conventional current control strategy, the VSC controls real and reactive power components of the DG unit. Subsequent to an islanding detection and confirmation, the current controller is disabled and the designed controller is activated. In this mode, the micro grid will provide a constant voltage to the local load. The proposed controller utilizes an internal oscillator for frequency control and a voltage feedback signal to regulate the island voltage. Here another control strategy is described for the intentional islanding operations of distributed power generations. And the performances of both controllers are compared.