Battery energy storage sizing based on a model predictive control strategy with operational constraints to smooth the wind power

The variability of wind power and forecast error not only increase the difficulty in using wind power but also bring security and stability issues into the power system. One of the solutions is to integrate an Energy Storage System (ESS) with the wind farm to accommodate the fluctuating wind power. This paper presents an approach of sizing ESS from the perspective of facilitating the integration of the wind farm. The control structure is twofold: the outer loop which determines the expected set-point power in the next hour and the inner loop which makes the actual output power follow the set-point power by charging/discharging ESS. In particular, operational constraints on ESS, such as maximum output power constraints and SOC constraints, are considered in the model predictive controller in the inner loop. According to the proposed control strategy, the average fluctuation rate of the wind storage system with different configuration capacities of ESS is calculated, and the results are visually presented in a sizing decision map. Finally, the most economical size of ESS is determined by presetting the dispatch fluctuation rate. The proposed sizing approach is applied to an actual wind farm in Fujian, China.