Date Added: Dec 2010
Observers for distributed fault detection of interconnected second-order linear time invariant systems are studied. Particularly, networked systems under consensus protocols are considered and it is proved that for these systems one can construct a bank of so called unknown input observers, and use their output to detect and isolate possible faults in the network. The application of this family of fault detectors to power networks is presented. Critical infrastructures such as power grids, water distribution networks, and transport systems are examples of cyber physical systems. These systems consist of large-scale physical processes monitored and controlled by SCADA (Supervisory Control And Data Acquisition) systems running over a heterogeneous set of communication networks and computers.