SoC management strategies in Battery Energy Storage System providing Primary Control Reserve

Nowadays, the deployment of grid-tied Lithium-ion Battery Energy Storage Systems (BESSs) is a promising technical solution to guarantee the security and reliability of the electric power system characterized by an increasing share of renewable sources. This paper studies BESS for Primary Control Reserve (PCR) provision by developing an approach to properly simulate BESS behaviour. The proposed approach consists of a controller that elaborates the input signals (frequency fluctuations and battery State of Charge) and returns a power setpoint for the battery, a simplified inverter model and the battery model which is the core part of the approach. Finally, economic analyses are detailed to evaluate the investment on a defined period. The case study is developed in Matlab™ Simulink™ and applied on the Italian regulation framework. Two different battery models are compared: empirical and electrical. Their different nature (e.g. model characteristics and complexity) brings to different results on the PCR service provision. The economic analyses highlight that the optimal design of the BESS is strongly influenced by the penalty costs connected to battery unavailability. In order to guarantee the service continuity SoC mitigation strategies are proposed and simulated; however, it is demonstrated that such strategies might cause a heavier battery utilization impacting on the BESS lifetime expectations and decreasing the investment profitability.