Determination of the optimal battery capacity based on a life time cost function in wind farm

Use of the battery energy storage system (BESS) as a power buffer becomes a feasible solution to mitigate the intermittent wind power characteristic. Due to the cost, utilizing an economical battery capacity is a crucial requirement of the system design. In this paper, dispatch power strategies are overviewed and the min-max method is selected as the most suitable one for integrating the wind power to grid. A lifetime cost function, which indicates the BESS cost spent to dispatch 1kWh, is defined with the dispatch principle so that the battery capacity can be optimized. With using the optimal capacity, the minimum system operation cost is achieved and the dispatched power is able to satisfy its scheduled reference in any dispatching time period. Moreover, the battery state of charge (SOC) is also managed to be in a safe range so as to guarantee the system undamaged. In order to clarify the proposed determination method, a case study with a 3MW permanent magnet synchronous generator (PMSG) wind turbine model is investigated.