An insight into the dynamics of loaded and free running isolated self-excited induction generators

This paper presents the loading analysis of an isolated induction generator and how the operating frequency and generated voltage are affected by the change in operating slip value. It also explains the effect of magnetizing inductance in self-excitation. The paper investigates the minimum and maximum value of speeds necessary to initiate the self-excitation process in an isolated three-phase induction generator for a given capacitance value and load. For a variable speed prime mover driving a self-excited induction generator (SEIG) with an input which is not controllable it is shown how to determine the limits of a given variation of speed so that the generator will continue to operate without loss of self-excitation. During self-excitation the variation in the value of magnetizing inductance, due to saturation, is the main factor that stabilizes the growing initial transient of generated voltage. The experimental and simulated results for dynamic generated voltage, frequency and power are presented. A DSPACE DS1102 DSP card is used for data acquisition and for control of speed.