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This report presents the work done to develop generator and gearbox models in the Matrix Laboratory (MATLAB) environment and couple them to the National Renewable Energy Laboratory's Fatigue, Aerodynamics, Structures, and Turbulence (FAST) program. The goal of this project was to interface the superior aerodynamic and mechanical models of FAST to the excellent electrical generator models found in various Simulink libraries and applications. The scope was limited to Type 1, Type 2, and Type 3 generators and fairly basic gear-train models. The final product of this work was a set of coupled FAST and MATLAB drivetrain models. Future work will include models of Type 4 generators and more-advanced gear-train models with increased degrees of freedom. As described in this study, the developed drivetrain model can be used in many ways. First, the model can be simulated under different wind and grid conditions to yield further insight into the drivetrain dynamics in terms of predicting possible resonant excitations. Second, the tool can be used to simulate and understand transient loads and their couplings across the drivetrain components. Third, the model can be used to design the various flexible components of the drivetrain such that transmitted loads on the gearbox can be reduced. Several case studies are presented as examples of the many types of studies that can be performed using this tool.

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Fidelity of a plant's dynamic model is a concern in any controller design process. In this context, fidelity refers to which dynamics of the plant needs to be included in the control model and which dynamics can be left out or approximated. Studies on wind turbine control have shown that modelling error due to the unmodeled dynamics can lead to unstable closed-loop dynamics. This paper investigates the use of Kalman estimator to design the Stochastic Disturbance Accommodating Control (SDAC) scheme to stabilize the system in the presence of the unmodeled dynamics. Performance of the presented control scheme is investigated through simulations on two different wind turbine configurations under turbulent wind conditions with different mean wind speeds and turbulence intensities using FAST (Fatigue, Aerodynamics, Structures, and Turbulence) aero-elastic tool. The generator speed regulation, drivetrain load, and control effort of the presented control scheme are compared with those of the baseline Gain Scheduled Proportional Integral (GSPI) controller. The results indicate better speed regulation and lower drivetrain load for the presented SDAC under the tested wind conditions.

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