Keywords

floating offshore turbine, hydrodynamics, Morison equation, wave kinematics, CRAFTS, TMD

Abstract

This thesis presents the development of a platform hydrodynamics module for floating offshore wind turbines (FOWT) within the Control-oriented, Reconfigurable, and Acausal Floating Turbine Simulator (CRAFTS), which is currently being developed in the Hybrid Sustainable Energy Systems Laboratory at UCF. The CRAFTS simulator is an acausal modeling and simulation environment developed utilizing the Modelica language. CRAFTS is capable of fully coupled multi-physics simulations of various types of FOWTs and facilitates Control Co-Design (CCD) of FOWTs.

This work describes an acausal approach for modeling the structure and hydrodynamics, and for verifying the control of a semi-submersible floating platform for a 15MW FOWT. The response of the floating platform to hydrodynamic loading is investigated in this thesis using the Morison equation approach in conjunction with the linear Airy wave theory. The CRAFTS simulator also incorporates a passive control strategy by implementing tuned mass dampers (TMDs) installed in the semi-submersible floating platform. These TMDs are finely tuned to mitigate the pitch resonance of the floating platform or the bending resonance of the tower. The results indicate that these TMDs can effectively diminish the platform's pitch or tower's bending motion in response to irregular wave conditions.

Parametric data of an actual prototype semi-submersible, that is used in a floating offshore wind turbine, were incorporated into the modeling, simulation, and control demonstrations. The model was also verified and validated using numerical data from the industry-standard simulator Open- FAST (developed by the National Renewable Energy Lab, NREL). Experimental data was available from the Floating Offshore Wind and Controls Advanced Laboratory (FOCAL) Project, a multi-institution research initiative in which our project was a participant. Results demonstrated that the hydrodynamics module in CRAFTS can qualitatively and quantitatively capture loads and responses of the floating structure under different wave conditions and control actuations with a low computational cost that enables rapid simulations.

In summary, this thesis discusses the development of a novel acausal hydrodynamics module in CRAFTS that supports Control Co-Design. The verification and validation results of this complex semi-submersible floating platform model enhance the applicability of CRAFTS to the modeling of other types of FOWTs. The work paves its way to further model improvements, including but not limited to incorporating second-order wave models and wave stretching.

Completion Date

2024

Semester

Spring

Committee Chair

Das, Tuhin

Degree

Master of Science in Mechanical Engineering (M.S.M.E.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Degree Program

Mechanical Engineering: Guidance, Control, and Dynamics Track

Format

application/pdf

Language

English

Rights

In copyright

Release Date

November 2024

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Campus Location

Orlando (Main) Campus

Accessibility Status

Meets minimum standards for ETDs/HUTs

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