Autonomous operation of wind-battery hybrid power system with maximum power extraction capability

The hybrid operation of a remote area power system consisting of a Doubly Fed Induction Generator (DFIG) based wind turbine, a battery storage unit and a dummy load is investigated in this paper. The battery storage unit operates as a source or load, depending on the wind power output and loading conditions of the system. The battery storage is connected to the AC side of the wind energy system through a three phase inverter to supply both active and reactive power. A dummy load is also incorporated into the AC side of the system. The design criteria of the controllers for each component (ie. DFIG, battery storage system and dummy load) and an approach for control coordination of the entire system are presented in this paper. The suitability of the proposed control coordination strategy and individual system controllers are tested in relation to the system voltage, frequency and DC link stability of the DFIG under variable wind and changing load conditions. The maximum power extraction capability from wind is also achieved throughout the operation.