Capacity specification for hybrid energy storage system to accommodate fast PV fluctuations

To accommodate the fast power fluctuations associated with PV generation, a hybrid energy storage system (HESS) consisting of a battery energy storage system (BESS) and super-capacitor is evaluated in this paper. A probabilistic approach for determining the power capacity specification for the HESS is proposed. This method would allow the capacities of the BESS and super-capacitor to be properly designed to optimize the characteristics of high energy density of the BESS and high power density of the super-capacitor. Results show that the super-capacitor within the HESS helps to mitigate the high frequency fluctuations, which contributes to the extension of BESS lifetime. In addition, the super-capacitor helps to address the peaks in solar power fluctuations without the severe penalty of round trip losses associated with a BESS. The proposed approach has been simulated using real PV generation data from an existing PV power plant in Long Island, New York.