Second life battery energy storage system for enhancing renewable energy grid integration

Connecting renewable power plants to the grid must comply with certain codes and requirements. One requirement is the ramp rate constraint, which must be fulfilled in order to avoid penalties. As this service becomes compulsory with an increased grid penetration of renewable, all possible solutions must be explored especially that large battery energy storage systems are still expensive solutions. Thus, in order to make battery investment economic viable, the use of second life batteries is investigated in the present work. This paper proposes a method for determining firstly, the optimal rating of a second life battery energy storage system (SLBESS) and secondly, to obtain the power exchange and battery state of charge profiles during the operation. These will constitute the cycling patterns for testing batteries and studying the ageing effect of this specific application. Real data from the Spanish electricity market for a whole year are used for validating the results.