Advanced control of large scale wind turbines

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\u27s 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