Studies on the use of conventional induction motors as self-excited induction generators

The suitability of using a normal three-phase induction motor as a capacitor self-excited induction generator (SEIG) is illustrated. The thermal limit of the stator windings being the limiting factor, the capacity of the SEIG is determined. The steady-state performance of such induction generators, maintaining a constant terminal voltage, is analyzed under resistive and reaction loads. Typical experimental results are also presented. It was found that, for low power motors, the maximum power that can be extracted as generators is 148% to 160% of the motor rating for resistive loads and 118% to 128% of the motor rating for 0.8 lagging power factor loads. Capacitive reactive volt-ampere (VAR) required to maintain constant voltage at 1.0 p.u. speed is in the range 85% to 140% of the power rating of the motor with resistive loads and 100% to 140% with lagging reactive loads