FT-ESO-Based Fixed-Time Secondary Control for DC Microgrids With Unknown External Disturbances

Reliable stability and fast response of DC microgrids are gaining wide attention, especially for those subject to disturbances imposed by renewable resources and uncertain loads. In this paper, a novel fixed-time extended state observer (FT-ESO) based secondary controller is constructed for DC microgrid with unknown external disturbances, enabling both voltage regulation and current sharing within a fixed settling time. In the control scheme, a novel compensation term together with an adaptive mechanism is designed to mitigate both disturbances and residual observation errors from FT-ESO, ensuring practical fixed-time convergence of the voltage and current tracking errors. This integration further improves the performance of convergence time and anti-disturbance. The proposed FT-ESO based controller is evaluated through MATLAB/Simulink simulations and experimental tests under several scenarios. Comparison studies further demonstrate the fast convergence rate and strong disturbance rejection capability of the proposed controller.