Optimization of power dispatch to minimize battery storage capacity in wind farm

Use of a battery energy storage system (BESS) becomes a feasible solution to mitigate the intermittent characteristic of wind power resource. Due to the cost, the minimal battery capacity is the crucial requirement to obtain the economic wind-battery system operation. In this paper, an optimal power dispatch strategy is proposed to minimize the storage capacity while the fluctuation mitigation requirement (FMR) imposed by grid codes is satisfied. The power dispatch which is determined through a first-order low-pass filter (FLF) is optimized by adjusting the filter smoothing time constant (FSTC). In order to optimize the FSTC, we introduce two online-based optimization methods that include a linear search approach and a direct computation approach. In the first method, the search objective is the appropriate FSTC to minimize the BESS capacity with a constraint that the power dispatch satisfies the FMR in a time window. In the second method, we demonstrate a mathematical relationship between the FSTC and FMR in 1-sampling time scale; therefore, the optimal solution can be directly computed. As a result, the proposed power dispatch strategy significantly reduces the BESS capacity. In order to verify the effectiveness of the proposed power dispatch strategy, case studies using a 3-MW wind turbine with real wind speed data are shown.