Date of Award
Master of Science in Ocean Engineering
In light of recent development in offshore wind, especially the need to develop floating wind structures in areas of deep water, improved methods of turbine control are becoming necessary. Floating Offshore Wind Turbines (FOWT) can be actively controlled to minimize their wave induced motions, improve wind energy harvesting efficiency, and increase structural life by reducing fatigue loads. The work done for this thesis is part of a collaborative initiative between the University of Rhode Island and the University of Maine, on a study titled ``Design, optimization, and control of floating offshore wind farms for optimal energy production," with funding by the Department of Energy. The problem of dynamically stabilizing a FOWT under wave loading requires understanding both waves and the dynamics of the floating structure, and we build on the idea that a control system can be improved with information of the future wave forces. To provide a controller with this wave preview, we develop Wave Reconstruction and Prediction (WRP) algorithms to be used on hardware such that they can be effectively used in the loop on a continuous real time basis. In the process of developing this tool, the quality of predictions is validated with numerically generated Numerical Wave Tank data, of which a large amount of results are presented here. In parallel, a Model Predictive Control (MPC) algorithm was developed which reflected the dynamics of a physical float possessed by our lab at URI. As a foundation, the effectiveness of the control system is validated in simulation, fed with the same NWT referenced previously. Results were in simulation were promising, where a wave preview helped minimize the overall float motions. Moving to a completely physical experiment has been an important component of this work. The design and construction of a validation scale moving ballast system, and the process of synchronization for the real time process are detailed in this text. Both the experimental and simulated studies limit the float motions to two degrees of freedom, roll and heave. Preliminary results of the physical experiment show mixed levels of success, where an improvement was seen in simple periodic wave states, while some bugs are still present in the process running in irregular sea states.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Albertson, Shawn, "REAL TIME PHASE RESOLVED WAVE FORECASTING FOR THE ACTIVE CONTROL OF FLOATING BODIES" (2023). Open Access Master's Theses. Paper 2371.