Smart control interface for robust operation of DG units in grid connected and Islanded modes

In this paper a flexible distributed generation (DG) control interface is being presents to be used in smart grid applications. The main objectives are to maintain hierarchical control framework; offer minimal control function switching during mode transition from grid connected and islanded modes and maximize the disturbance rejection performance of the DG interface against network and load during grid connected or islanded mode operations. To achieve these objectives, a fixed voltage-current cascaded control structure with robust internal model control-based voltage controller and a power flow controller is proposed to maximize the disturbance rejection performance within the DG interface and to minimize control function switching. The effectiveness of the proposed control scheme is evaluated via simulation results for different operating scenarios.