Fixed-Time Active Disturbance Rejection Control Scheme for Hybrid Energy Storage System Based on Cascaded Extended State Observer

To suppress the bus voltage fluctuations caused by disturbances such as photovoltaic-side power fluctuations and load-side power variations in hybrid energy storage systems, a fixed-time active disturbance rejection controller (FxADRC) integrated with a cascaded extended state observer (CESO) is proposed in this paper. The paper first constructs a dynamic model of the hybrid energy storage system, considering the impact of disturbances. Second, this paper designs a cascaded extended state observer to estimate the total disturbances affecting the system, achieving finite-time convergence performance. Then, a fixed-time sliding mode active disturbance rejection control strategy combined with the CESO is proposed, which can achieve bus voltage tracking with fixed-time convergence rate irrespective of the effect of the initial state. In addition, the stability of the proposed controller is validated by the Lyapunov method. Finally, Comparative studies are conducted by simulation to verify the effectiveness and outstanding performance of the proposed control scheme.