A Technoeconomic Assessment Methodology of Energy Storage Systems for Dynamic Frequency Regulation

Frequency-regulation markets are becoming more dynamic and placing a greater premium on fast frequency response that requires energy-storage systems, such as batteries, to provide high-quality response. While batteries can technically provide this service, the continuous cycling leads to faster degradation. Ultracapacitors can be cycled rapidly without degrading, but are more expensive for storing large amounts of energy. Therefore, a battery and ultracapacitor hybrid energy-storage system (HESS) may provide the ability to provide effective fast frequency response and reduce degradation. In this paper, we present a methodology for performing technoeconomic assessment of an HESS participating in Pennsylvania-New Jersey-Maryland Interconnection's (PJM's) dynamic frequency-regulation market (their fast frequency-response product). In particular, the proposed method uses performance measures, battery -degradation modeling, and financial investment return for different input-power allocations to the battery and ultraca-pacitor components of the HESS system during fast frequency-regulation services. The paper evaluates the proposed approach on a fully-active HESS topology using the fast regulation signal (RegD) from the PJM market. Our experimental results reveal that the input regulation power allocation has a significant impact on HESS performance, battery degradation, and 5-year investment return. This work also highlights the importance of developing an optimal sizing tool for HESS to provide better performance measures and financial benefits during participation in regulation services.