Decentralized active fault tolerant control of direct current microgrids under actuator and source disturbances using proportional integral unknown input observer

This paper introduces a decentralized active fault tolerant control technique for actuator faults in a DC microgrid with load variations and source perturbations without requiring communication between distributed generators or load current measurement. The proposed control technique consists of two sections, each designed separately. One section aims to maintain the system's stability and desired performance; the other section compensates for the actuator fault through fault reconstruction. To achieve this, a decentralized unknown input proportional-integral observer (UI-PIO) estimates the fault accuracy regardless of the load variations. The proposed linear quadratic regulator (LQR)-based UI-PIO strategy optimizes the trade-off between control performance and energy consumption, ensuring efficient operation under normal conditions and minimizing disruptions during fault states while robust to load variation. The stability and robustness of the closed-loop system under load variations are ensured through Lyapunov's conditions, solved by the linear matrix inequality technique. The proposed decentralized LQR-UI-PIO circumvents the limitations of load variations, source perturbations, and actuator fault by allowing local controllers within the MG to independently compute control actions based on locally available information and a shared global objective. Finally, the hardware-in-the-loop setup is implemented to evaluate and validate the efficiency of the proposed decentralized fault-tolerant technique. The obtained results highlight the effectiveness and efficiency of the proposed approach in detecting and reconstructing faults, maintaining stability, and improving performance, which makes this approach of interest in other industrial applications.