Analysis of the maximization of wind turbine energy yield using a continuously variable transmission system

In this paper, an analytic study of the subject of mechanical power transmission in HAWT wind turbine has been carried out. For the most part, the study analyzes the use of continuously variable transmission (CVT) in order to allow the turbine and the electric generator to couple, allowing in turn, an unremitting transmission ratio adjustment. In low-wind sites, the design criteria suggest an oversizing of the wind turbine in order to generate adequate electrical power even at low wind speed. The proposed solution enhances the space of operating points since it allows the electric generator to release the rotational speed from the turbine one (limited due to structural integrity). Employing a CVT transmission, the modulation system of the input power to the turbine starts operating at higher wind speeds when compared to a conventional direct-drive case: this corresponds with the possibility to fully exploit the wind power at a higher speed range, therefore maximizing the wind turbine’s energy production. The analysis has showed that, in the case of CVT configuration, the annual energy yield increases of about 50% compared to direct-drive solution.