Reduced-Order Observer Design for Small-Signal Multi-Machine Power System Stability Improvement by Optimal Control

In this paper, we present the design of an observer of reduced-order used, in cascade, with optimal control to improve the small-signal stability of a multi-machine power system. The limitation of the measurement of all state variables of the system requires the design of reduced-order observer to reconstruct the unavailable part of the state variable vector. The non linear system is first linearized, and then a state space model is constructed. The optimal control is calculated with an interesting method which is briefly presented. The main construction of the observer is illustrated and the observer gain is calculated with the minimization of a quadratic index.