Formulation of an Operation Theory for Wind-Generators with Controlled Variable Speed-Ratio

Abstract

The basic variables relevant to wind generation systems were formulated in this study as to relate the operational torque coefficient to the power output and wind velocity. A dimensionless number connecting wind velocity, power output, generator speed, turbine size and air density was identified and shown to be the pivotal independent parameter of the wind-generator operation.

An optimization criterion based on this mathematical formulation was developed. It relates the gearbox's speed-ratio to the newly defined wind generator number. This led, in turn, to the introduction of a variable speed-ratio gearbox that has a constant speed output and a variable turbine shaft-speed to be controlled in such a way as to match continuously and optimally the operation condition.

Making use of a reported experimental study of a variable pitch-angle turbine driving an induction generator, a demonstration of the design procedure was presented. The model was shown to accurately predict the experimentally produced results. The demonstration proceeded to predict the optimum performance for the reported system.