Adaptive control of energy storage systems for power smoothing applications

Energy storage systems (ESSs) are desired and widely applied for power smoothing especially in systems with renewable generation and pulsed loads. High-pass-filter (HPF) is commonly applied in those applications in which the HPF extracts the high frequency fluctuating power and uses that as the power reference for ESS. The cut-off frequency, as the critical parameter, actually decides the power/energy compensated by ESS. Practically the state-of-charge (SoC) of the ESS has to be limited for safety and life-cycle considerations. In this paper an adaptive cut-off frequency design is proposed for systems with multiple ESS units to realize several objectives simultaneously including SoC limiting, SoC balancing and power smoothing. Experiment is conducted considering a pulsed load profile. The results demonstrate the effectiveness of the proposal concerning the mentioned control objectives.