Novel unknown input observer for fault estimation of gas turbine dynamic systems

In this paper, an innovative unknown input observer (UIO) is developed to estimate the faults of the system subjected to faults and process disturbances. By representing the concerned faults as auxiliary states, an augmented system is constructed. By designing an unknown input observer for the augmented system, the simultaneous estimations of the system states and concerned faults can be obtained readily. In this study, the unknown input disturbance is not assumed to be decoupled completely. The integration of the UIO technique and the linear matrix inequality (LMI) optimization technique is proposed to decouple and attenuate the input disturbances. The existence condition of such an observer and the design method of the observer gains by using the LMI are addressed as well. Finally, the proposed algorithm is applied to the simulation study of a three shaft gas turbine system to show the excellent fault estimation performance.