Milenko Stegić

Torsional oscillations of the turbine-generator due to network faults

A model of the electromechanical system, suitable for the analysis of torsional oscillations due to the power systems faults, is established. Results of an example of computer simulation of transient torsional torques in the shaft-line due to a three-phase fault and the subsequent fault clearing, as obtained by the model, are presented. Effect of chosen fault clearing time is discussed.

Nonlinear Problems in Dynamics by the Finite Element in Time Method

The finite element method in time domain is a fast and reliable numerical method for predicting the steady state response of the nonlinear dynamic system under periodic excitation. The stability of solutions can be investigated by the application of Floquet-Lyapunov theorem on the transition matrix. Close agreement is found between obtained results and the published findings of a harmonic balance method.

Bifurcation of Periodic Solutions in the Two-Degree-of-Freedom System With Clearances

Clearances exist in many mechanical systems either by design or due to manufacturing tolerances and wear. The characteristics of such systems include abrupt variation of stiffness usually approximated as piecewise linear. It is well-known that the stiffness discontinuity can be a source of the instabilities in the dynamic behavior of the system.