The current trend of increased penetration of renewable energy and reduction in the number of large synchronous generators in existing power systems will inevitably lead to general system weakening. The inherent characteristics of traditional synchronous machines will have to be replaced by converter-interfaced sources. The intermittent nature of renewable sources points to a need for high capacity energy storage. Battery energy storage systems (BESS) are of a primary interest in terms of energy storage capabilities, but the potential of such systems can be expanded on the provision of ancillary services. In this chapter, we focus on developing a battery pack model in DIgSILENT PowerFactory simulation software and implementing several control strategies that can address some of the issues mentioned previously. The last section of the paper contains a demonstration of the capabilities of the battery system and evaluation of the implemented functions in various operating scenarios.