Fully Distributed Unknown Input Observer Based Fault Detection for Interconnected Systems

In this article, a set of fully distributed unknown input observers (UIOs) are designed for continuous-time linear interconnected systems. As a fully distributed scheme, each subsystem uses only local and interconnected information with neighbors to design the UIO, and then their data to monitor the local state. By unknown input decomposition, the UIOs can asymptotically estimate the state of interconnected systems in the presence of actuator faults. The presented scheme is scalable, allowing plug and play (PnP) operations. Then, a Luenberger observer is constructed for each subsystem, which interconnected with UIOs for the other subsystems is utilized to construct the fault detector. The residual generated by the fault detector is sensitive to the local fault while decoupled with faults in the other subsystems such that distributed fault detection for interconnected systems with more than one faulty subsystems is feasible. Finally, simulations are conducted for fault detection on power networks to show the effectiveness of the proposed method.