Structural Estimation and Optimal Control of Floating Wind Turbines

To support the growing interest in digital twins and advanced control methods for floating wind turbines, this thesis investigates an analytical approach to designing a real-time structural dynamics observer. Using standard linear and non-linear Kalman filtering methods, displacements and velocities of the floating hull, tower, and blades are reconstructed from IMU and strain gauge measurements. The method is validated using both experimental data from a 1:70 scale 15MW FOWT model and numerically generated data from the open source time-domain FOWT simulation software OpenFAST for a 5MW and 10MW FOWT. To demonstrate the application of the structural observer, the developed method is used to design a linear quadratic gaussian (LQG) controller for a 10MW semi-submersible FOWT. The controller is implemented in OpenFAST coupled with Simulink and compared to an existing FOWT controller ROSCO and shows improved performance over a range of normal and extreme operating conditions.