Synchronous generators are characterized by a nonlinearly interacting electrical and
mechanical dynamics. Accurate and robust state reconsh-uction of this machine by an
observer should be based on its nonlinear dynamic behavior to avoid intolerable errors. The
authors of this paper had published a methodical design of a fill1 order nonlinear observer for
turbogenerator systems and organized its experimental validation on a 120 MVA and 1000
MVA synchronous generators at Gud-Power Station in south Munich (Germany) and the
Nuclear Power Station of Gosgen (Switzerland), Measured results from these power stations
have proved a quite effectiveness of the proposed methodology on getting a stationary robust
state reconstruction. However, some transient results are characterized with state
oscillations. To prevent such transient oscillations, this paper introduces an optimum
technique for the selection of the observer feedback constants. Moreover, additional signals,
such as real, reactive and apparent power as well as the amplitude of the stator current are
used for the observer feedback. These signals have proved to enhance damping of the
observer states transient oscillations.