Energy Storage Sizing Based on Automatic Frequency Restoration Reserve Market Participation of Hybrid Renewable Power Plants

Energy Storage Systems are expected to play a key role in the transition towards increasing the renewable energy share in electrical grids. In order to ensure their profitability, sizing these systems becomes a decisive task. In this study, we propose a sizing method for Battery Energy Storage Systems (BESSs) based on their participation in the Automatic Frequency Restoration Reserve (aFRR) Market. The revenues of this market are linked both to the power band offer and to the real-time energy required. In this context, different case studies are considered to analyze the sensitivity towards these parameters. Battery selection is conducted by performing simulations with a novel optimization formulation, in which the expected aFRR requirement is considered. Results show that the BESS profitability has a great dependence on the aFRR demand and, for a high aFRR requirement case, low power and low capacity batteries (2.5 MW power and 1 h capacity) are the best option.