Date of Award

Spring 2010

Project Type


Program or Major

Electrical Engineering

Degree Name

Master of Science

First Advisor

L G Kraft


Wind turbines have experienced an economy of scale that caused them to become larger, more expensive and provided the challenge to protect the components, particularly the failure-prone gearboxes. This thesis focused on new control systems for wind turbines in above-rated, or Region 3, wind regimes. The control goals were to regulate the generator speed and protect the gearbox by mitigating drivetrain torque variations.

This thesis included the development of a linear wind turbine model based on the National Renewable Energy Laboratory's FAST 5MW model. A magnetic continuously variable transmission (CVT) was included in the model. A multi-input linear quadratic regulator (LQR) controller was developed and simulated. The multi-input controller provided large improvements in speed regulation and torque variation reduction when compared to blade-pitch industry standard proportional-integral and single-input LQR controllers. Results indicated that use of a magnetic CVT and multi-input LQR controller could reduce fatigue on wind turbine gearboxes.