Sizing of energy storage for hybrid power plants aiming for turbine stress reduction under FCR-N requirements

This paper examines the storage sizing for hybrid power plants providing the Frequency Containment Reserve (FCR) for power grid balancing, where the hybridization of a turbine with energy storage system aims to decrease turbine stress under the most recent Nordic FCR requirements. This objective is addressed via the formulation of a hybrid plant optimal control problem, focusing on the achievable stress reduction as a function of storage energy capacity. The analysis of the optimization problem provided an analytical representation of the least upper bound for the best attainable turbine stress reduction, which was used to derive sizing recommendations for energy capacity. The obtained results imply that the hybrid plant’s control policy has a significant impact on the achievable stress reduction, as relatively small energy capacity can provide a high-stress reduction with “well–designed” control. • Sizing method for storage capacities under FCR-N requirements. • The best attainable upper bound for stress reduction with a given energy capacity. • Formulation of hybrid plant control problem targeting turbine stress reduction.