Effects of including automatic excitation control in transient field simulations of hydrogenerators

This paper addresses effects of automatic excitation control in time-stepped finite element analysis of hydroelectric generators. A simple method to incorporate exciter and automatic voltage regulator models in a finite element software is presented and tested on a small hydropower generator connected to a three-phase power system equivalent. Three simulations are performed to demonstrate the impact of the controller and to compare the field voltage and the field current as two possible excitation source variables. It is shown that inclusion of the excitation system greatly enhances the damping of rotor-angle oscillations and that the field voltage should be chosen as source variable to include the transient field winding inductance in the field problem.