Battery energy storage in standalone microgrid: Synchronization and transfer between operating modes

This paper presents control scheme for a standalone microgrid having a non-dispatchable fixed-pitch variable-speed wind turbine generator (WTG) and a battery energy storage (BES). The WTG is directly interfaced at a point of common coupling (PCC) and the BES is interfaced at the PCC via a bidirectional DC-AC converter. The unique aspect of the control strategy is that the BES not only regulates voltage and frequency at the PCC by active-reactive power compensation, but also ensures proper synchronization and disconnection of WTG during the wind velocity variations for seamless transfer between these operating modes with and without WTG, while providing an uninterruptible supply to critical load. Performance under each operating mode and transitions is tested through modeling and implementation of control algorithm in MATLAB/Simulink environment to demonstrate the capability of the scheme.