THE ROLE OF MAGNETIZING REACTANCE IN STEADY-STATE PERFORMANCE OF INDUCTION GENERATORS

The paper presents a computational method for predicting the load perf ormance of a stand-alone induction generator. A mathematical model der ived from the generator equivalent circuit is used as the basis for th e computation. In the model, the minimum value of capacitance necessar y for the machine to serf-excite is the critical factor. This minimum value is both load- and speed-dependent. The magnetizing reactance is nonlinear, and its value is affected by the capacitance used for excit ation. This nonlinear variation of magnetizing reactance related to th e exciting capacitance defines a critical maximum and a critical minim um value of reactance. The terminal voltage, terminal frequency and ge nerator efficiency are calculated from the model for a wide range of l oad impedances and power factors. Close correlation between measured a nd calculated results gives confidence in the model, which provides a basis for VAR compensator design in stand-alone micro-hydro systems.