Announcing the Final Examination of Kazi Ishtiak Mohsin for the degree of Master of Science
This thesis involves the modeling, validation, and control studies of a Control-Oriented, Reconfigurable, and Acausal Floating Turbine Simulator (CRAFTS), that is currently under development. CRAFTS uses Modelica®, an object-oriented, declarative, multi-domain modeling language for physical system modeling in the Dymola environment. The CRAFTS simulator facilitates rapid dynamic simulation of wind turbines with various model variants and enables control co-design. A major emphasis of this thesis is in the validation of the CRAFTS simulator for a 15-MW land-based wind turbine through several test cases. These test cases were collaboratively developed in conjunction with other participating research entities. CRAFTS has undergone rigorous testing, with a particular emphasis on comparison against the industry standard OpenFAST platform (developed by the National Renewable Energy Lab (NREL)) as well as experimental data. Open loop testing scenarios scrutinize the wind turbine dynamic conditions such as varying rotor speed and pitching angle maneuvers. Diverse combinations of ramp and step commands have been employed to modulate rotor speeds and pitching angles. Validation results indicate very good agreement between CRAFTS and baseline results. CRAFTS was also tested under various types of closed-loop control scenarios, such as different types of wind profiles and various wind velocities. Wind types encompass stepped winds, wind gusts, steady winds, and sinusoidal wind patterns. In closed loop testing, firstly an industry standard controller ROSCO (also developed by NREL) was used. Thereafter, a nonlinear controller developed in our prior research was implemented and investigated. The closed loop performance of the CRAFTS model was compared with OpenFAST. The tests confirmed the validity of the CRAFTS model under closed-loop and also validated the nonlinear controller. The work was a critical element in the development of the CRAFTS simulator. Validation tests provided valuable insight into the accuracy of the underlying physics and often provided valuable feedback that led to model improvements. The work has laid the foundations for more advanced research, especially in the area of multivariable control design for floating offshore wind turbines.
Committee in Charge:
Tuhin Das, Chair, Mechanical and Aerospace Engineering
Jeffrey Kauffman, Professor
Yunjun Xu, Professor