On the estimation of the transient state of a synchronous machine by an optimal observer

This paper presents a new optimal observer which estimates the transient state of a synchronous machine. The optimal observer, which is a state estimator with decaying error at a desired speed, is constructed by using the non-linear transformation of Letov (1960). The proposed observer is then applied to the reconstruction of the entire state vector for a single machine connected to an infinite bus. Also, in order to demonstrate the feasibility of practical implementation of the optimal controller obtained by Yamashita et al. (1982), the performance of the system with the optimal observer cascaded to this controller is compared with that obtained by the conventional control.