Unknown Input Observer Based Robust Actuator Fault Detection and Isolation in Interconnected Power Systems

In this paper, the performance degradation of a generating unit in a multi-area power system regulated by an area-wise decentralized load frequency control is detected and isolated via a scheme of unknown input observers. This scheme is robust to the changes in the load demand, which are considered as the unknown inputs. The actuator faults studied in this work are meant to be the performance degradations in generating units under load frequency control. Both stuck and non-stuck actuator faults are analyzed and the performances of the proposed method in both cases are tested through computer simulations on a two-area power system composed of five generating units. The results show that a performance degradation in any generating unit can be detected and isolated successfully provided that the faults in the sensors measuring generator outputs are absent.