An Improved Speed Sensorless Control of Self Excited Induction Generators Considering Magnetic Nonlinearity

Abstract

Self excited induction generators (SEIG) are widely used for wind power generation in remote areas. The challenge is to maintain constant voltage and frequency under variable load and variable wind speeds. In this paper a reactive power control technique of the generator partially through fixed capacitor bank connected at the stator terminals and switched dc power source is proposed for constant voltage operation. The dc power source can be a battery charged from a solar module and from the generator during light loaded condition. The capacitor provides the bulk excitation current for the induction generator (IG) while the inverter adds the reactive current needed to regulate the IG output voltage under variable wind speeds and loads. The method is simple and can also be applicable for a wider speed range of operation. Different simulations and experiments are performed on a real machine to validate the proposed concept. 