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Department of Electrical and Computer Engineering, University of Kuwait, P.O. Box 5969,

Safat 13060, Kuwait

ABSTRACT

The paper presents a computational method for predicting the load performance of a standalone induction generator. A mathematical model derived from the generator equivalent circuit is used as the basis for the computation. In the model, the minimum value of capacitance necessary for the machine to self-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 excitation. This nonlinear variation of magnetizing reactance related to the exciting capacitance defines a critical maximum and a critical minimum value of reactance. The terminal voltage, terminal frequency and generator eficiency are calculated from the model for a wide range of load impedances and power factors. Close correlation between measured and calculated results gives confidence in the model, which provides a basis for VAR compensator design in stand-alone micro-hydro systems.