Li-ion batteries and Li-ion ultracapacitors: Characteristics, modeling and grid applications

This paper presents two of the most promising compact energy storage types, Li-ion batteries and ultracapacitors, for grid applications. Different types of lithium-ion batteries are discussed and compared and a generic electrical model for this type of batteries is presented, which models the battery dynamics, capacity, efficiency, and performance. Characteristics and electrical equivalent model of the Li-ion capacitors are also presented and discussed. The electrical models are verified for both devices by conducting extensive testing. Various grid level applications of these energy storage elements including renewable integration, ancillary services, energy time-shifting, and applications in islanded grids are discussed.