Modelling and control of a wind-driven induction generator for water storage heating

The paper discusses the concept of using a self-excited induction generator, driven by a wind turbine for water storage heating. An accurate mathematical model of the generator is used to establish, as functions of angular velocity, the particular variations of excitation capacitance and load resistance, which simultaneously cause the turbine to run at optimum tip-speed ratio and maximise the generator efficiency. Since it is not feasible to implement these variations exactly, and approximation is derived which users fixed resistive and capactitive elements in conjunction with switched capacitors. The latter, under feedback control, impose a variation of terminal voltage with angular velocity, which is such as to cause the turbine to operate at optimum tip-speed ratio and the generator close to optimum efficiency.