Stand alone induction generator with terminal impedance controller and no turbine controls

Induction generators with hydraulic turbines are often used for cogeneration. The same turbine generator configuration can be used for stand-alone generation if an impedance controller is connected to the generator terminals; this configuration requires no hydraulic controls on the turbine. The authors propose an electronic impedance controller to control the voltage and the frequency of a stand-alone induction generator. The controller concept and its control range are discussed. Particular attention is given to the harmonic distortion caused by the controller and measures to reduce these distortions. The controller design is discussed, and data from an experimental generator set are provided to verify the proposed concept