Decentralized power allocation with integrated bus voltage recovery for hybrid energy storage systems

Abstract

Abstract A hybrid energy storage system (HESS) plays a crucial role in stabilizing DC microgrids against power fluctuations from renewable sources and loads. To mitigate severe bus voltage deviations under complex disturbances, this paper proposes a composite control method integrating a super-twisting sliding mode controller (STSMC) with an extended state observer (ESO). Combined with virtual impedance droop control, the proposed method enables coordinated power sharing in the HESS, where the ESO estimates disturbances and the STSMC improves transient performance. A decentralized secondary voltage recovery (SVR) strategy with decoupled battery (BAT) and supercapacitor (SC) control is further introduced to restore the bus voltage and rapidly recover the SC state of energy (SOE). Under the proposed scheme, the BAT handles low-frequency power components, while the SC compensates for high-frequency fluctuations. Simulation and controller hardware-in-the-loop (CHIL) tests validate the effectiveness of the proposed method in improving the dynamic response and stability of the HESS.