Modeling and Control of Magnetic Gear Dynamics in a Wind Turbine Drivetrain

This thesis looks at the modeling and simulation of linear and nonlinear magnetic gear dynamics in a wind turbine drivetrain. The objective is to lay the groundwork for analysis, modeling and optimization of control structures focused on pole-slip prevention. A classical mechanical two-mass torsion spring model is used as the basis for developing the dynamic system equations and Simulink models. The wind turbine torque input to the low speed rotor is modeled as a disturbance input, the generator torque is modeled as a controlled input, and the high-speed rotor speed is the only measured output. The nonlinear dynamics are linearized; and a state space model is built that utilizes both gear rotor speeds and the load angle as states. A state space feedback compensation controller is designed using pole placement techniques; and the sensitivity of the selected poles is tested across the full range of rated load angles. A full order observer is combined with state feedback compensation and the performance is evaluated with and without load angle speed regulation and integral action. A reduced order observer is designed with load torque estimation as an additional metastate , which is then used to calculate the load angle, providing a better estimate than what the observer directly provides. Finally, the accuracy of the reduced order observer is tested using real torque data from a wind turbine