Autonomous Predefined-Time Distributed Control for Multihybrid Energy Storage Systems With State-of-Charge Balance

This article proposes an autonomous predefined-time distributed control (PDTDC) strategy for multihybrid energy storage systems in DC microgrids. The strategy enables an adjustable current sharing ratio and voltage regulation within a predefined time, while also maintaining state-of-charge (SoC) balance among energy storage units. The predefined-time disturbance observer (PDTDO) is developed to estimate mismatched disturbances, such as parameter uncertainties and load variations. Based on local and global average information, an adaptive correction factor is proposed to alleviate reliance on prior knowledge and allow the control gain to be adjusted autonomously. The proposed auxiliary controller does not depend on the current data of the adjacent units, which facilitates practical implementation. Compared with some finite-time and fixed-time approaches, the proposed controller achieves predefined-time convergence regardless of the initial conditions, with the upper bound of the convergence time determined by a predefined adjustable parameter. Finally, simulations and experiments validate the effectiveness of the proposed PDTDC approach under scenarios involving sudden load switching, plug and play, and link failure.