Variable speed constant frequency power generating system by the use of rotor excitation of induction machine

Stand-alone, diesel engine-driven synchronous generators have been widely used for emergency supply of plants, isolated islands, etc. Even though the speed of the diesel engine is controlled using high performance governors in order to keep the output frequency constant, the output frequency changes when there is a step change in the load. In this paper, we propose a new stand-alone generator that uses the rotor excitation of a wound-rotor induction machine. We show that the proposed power generating system maintains a constant amplitude, constant frequency output voltage despite several percentage change in the rotor speed