Variable speed constant frequency stand-alone power generator using wound-rotor 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, an inverter and capacitors. We show that the proposed power generating system maintains a constant amplitude, constant frequency output voltage despite several percentage change in the rotor speed.