Optimal estimation of the generalized operational impedances of synchronous machines from short-circuit tests

A nonlinear procedure for estimating the dynamic constants of a synchronous machine from sudden short-circuit data is presented. The machine, which is assumed to be operating in a quasi-linear mode, is modeled by operational impedances of a suitable order. By conferring much greater flexibility in the choice of the number of damper windings in each axis, the proposed method of analyzing short-circuit oscillographs is particularly appropriate when the machine is a solid-rotor turbogenerator. By means of a canonical state variables realization of the machine admittance matrix, the proposed algorithms permits an optimal estimation of the three classical operational impedances in a time-domain framework. It is then possible, by means of a few classical approximations, to deduce algebraically the equivalent circuits of the turbogenerator