Comparative study on the performance of a commercially designed induction generator with induction motors operating as self excited induction generators

The paper presents the performance characteristics of different induction machines of various ratings operating as a capacitor self-excited induction generator. Their computed performance is compared with commercially designed line excited induction generators operating as self excited induction generators. An algorithm, using the Newton-Raphson method and steady state equivalent circuit for the machine, is developed to compute the excitation requirement for maintaining a constant terminal voltage at different loads. This technique is also used to compute the number of capacitor steps required to load the machine, from no load to full load, while maintaining terminal voltage within specified limits. The optimum output power of the machine is computed without exceeding the rated stator current for its rated speed. The voltage range within which the machine is expected to operate at or above its rated capacity in stand alone mode, but without being overloaded, is also obtained. The effect of speed on excitation requirements is studied.