Resilient Distributed Observer-Based Fault-Tolerant Control for Islanded AC Microgrids Subject to Actuator Fault and Saturation Constraints

This study presents a novel disturbance observerbased distributed predefined-time fault-tolerant controller (DOBDPTFTC) to achieve precise frequency and voltage regulation, as well as accurate power sharing, in islanded AC MGs subject to actuator fault and saturation constraints. The actuator fault can result in poor performance of the controller, thus degrading the dynamics of the MGs. Predefined-time observers are designed to estimate the disturbances that are caused by the actuator fault within a predefined time. Furthermore, owing to the practical physical limitations of the islanded AC MGs, the output of the actuator will suffer from saturation. The controller saturation is taken into account and a saturation compensation system is designed to remedy the effect of the controller saturation. Besides, the average voltages of all DGs are obtained by a distributed predefined-time observer (DPTO). Then, based on the observations of the disturbances, the DOBDPTFTCs are proposed to guarantee frequency/voltage regulation together with power sharing in a predefined time, which is determined by a tunable parameter. The islanded AC MG with actuator fault and saturation is verified to be predefined-time stable under the proposed DOBDPTFTCs through the Lyapunov theorem. Simulation analysis and hardware-in-the-loop experiments are performed to comprehensively assess the performance of the DOBDPTFTCs in islanded AC MGs.