Selection of Gearbox Ratio and Power Converters Ratings for Wind Turbines Equipped With Doubly-Fed Induction Generators

This paper presents a methodology for the optimal selection of the gearbox ratio and the power converters ratings of a doubly-fed induction generator (DFIG) drive associated to a wind turbine. The design process of such an electromechanical system needs suitable compromises between the performances of the wind turbine on the whole speed range and the respective characteristics of the induction machine, the gearbox and the static converters. The optimal solution in terms of performance and cost must be derived from a global design approach. For a given turbine, a given DFIG and a given annual wind distribution, a suitable compromise must be found between the gearbox ratio and the sizing of the power converters to maximize the annual energy yield. This paper presents a methodology that can be used for the optimal determination of these two important variables of the design process, in terms of annual energy yield and initial cost. The proposed approach is applied to a 2MW wind turbine.