Optimal Economical and Technical Sizing Tool for Battery Energy Storage Systems Supplying Simultaneous Services to the Power System

The present work describes a tool for the optimal technical and economical sizing of a battery energy storage system (BESS) designed for the supply of simultaneous different services to the Power System (PS). The tool is based on a linear programming mathematical model. The objective function is the maximization of the ratio between the total incomes and the investment cost, which is dimensionally the inverse of a time and thus is strictly related to the Pay-back Time of the investment. Appropriate constraints take into account the technical requirements imposed by regulations related to the considered services. The following ancillary services for power-frequency regulation have been considered as suitable for a BESS: frequency containment (i.e. primary frequency control) frequency restoration (i.e. secondary frequency control) replacement (i.e. tertiary frequency control). Participation to the Day-Ahead Market is also considered, as well as the coupling of the BESS with a Nonprogrammable Renewable Energy Sources (RES) generator in order to reduce the economical penalties consequent to its imbalances. The model have been applied to a case study on the Italian Power System, where all the above mentioned services are remunerated.