Design and operation strategy for multi-use application of battery energy storage in wind farms

Wind power plants have become a mainstay of renewable energy production, especially in Germany, and they accounted for 21 % of the gross electricity production there in 2019. Nonetheless, energy production from wind turbines depends on the weather and wind farms require active power from the electrical power system in windless periods. Battery energy storage systems (BESS) are well suited to increase the integration and optimal utilisation of wind energy and reduce the significant energy consumption cost. In this paper, the authors present a methodology to size a BESS for self-consumption in windless times optimally and operate the BESS in a technically and economically optimal way. For the latter, a multi-use operation strategy is developed, where the BESS reduces energy demand in windless periods, balances forecast deviations in its balancing zone and stores energy from wind power curtailment. Mixed integer linear programming is used to identify the optimal operation strategy for the wind farm storage system considering intra-day energy market prices and imbalances. Furthermore, BESS market participation factors are introduced that are used to consider BESS' payback time and lifetime in the development of the optimal multi-use operation strategy. The methodology proposed is verified in a case study using real wind farm measurements, forecasts and market data for Germany. It has been verified that the multi-use operation developed is economically attractive. Furthermore, the energy demand of a wind farm has been reduced by about 13 % and imbalance costs by about 37.5 %.