Control Strategy for Seamless Transition of Microgrid Using Battery Energy Storage System

The transient over/under voltage and frequency during operation mode transition of microgrid is the key trouble in microgrid operation, i.e. seamless transition. To overcome this problem, this paper proposes modified control scheme in battery energy storage system controller based on master-slave control strategy. Main objective of this control scheme is seamless transition especially when grid-connected microgrid is transferred to islanded mode due to fault in main grid. A static transfer switch signal at point of common coupling is used to be the trigger sign for control method changing from PQ to V/f control mode. The proposed method is validated in Mae Sariang microgrid case study using DIgSILENT. For seamless transition conditions, the microgrid's voltage amplitude, frequency limit, and clearing time are defined by IEEE 1547 standard. The simulation results illustrate that when fault occurs, microgrid seamlessly transfers to islanded mode by proposed controller. In addition, the range of battery SOC that guarantees the seamless transition for critical load is discussed.