An Optimized Frequency and Voltage Control Scheme for Distributed Generation Units of an Islanded Microgrid

Frequency and voltage regulation is an issue of utmost importance when the microgrid is islanded. During islanding, the loads in the system are reallocated to be shared by the distributed generations (DGs) leading to voltage and frequency shifts. These variations should be such that the load does not experience transients. Therefore, an optimization based scheme is proposed for minimizing both frequency and voltage deviations. In the proposed work, the DG unit having largest capacity in the microgrid is assigned as the master controller. This controller calculates the optimized frequency and voltage deviations dynamically at different load levels. Similar procedure is followed by other DG units for setting their respective phase angle and voltage references for individual inverters. Therefore, simultaneous control of frequency and voltage is achieved with proper load sharing among the DG units. Simulations performed in MATLAB/Simulink justify the effectiveness of the proposed controller.