The theory and effects of neglecting stator and network transients

The reduced order linearized equations of the induction machine are derived. Analytical results are developed to show that a ratio of machine parameters may be used as an indication of the accuracy of the eigenvalues predicted by the reduced order model. Large excursion studies of induction machines are presented and the accuracy of the results is shown to be dependent upon the machine parameters and type of study when the stator transients are neglected. Results are presented which show that it is not generally acceptable to neglect the stator and network transients when turbine generator shaft torques are of interest. It is shown that the magnitude of shaft torques resulting from faults in the system is very dependent upon the impedance between the machine and the point of the fault. A method is developed to allow the use of a modified standard transient stability program for the calculation of shaft torques.