Station keeping analysis and design for new floating offshore wind turbines
- Autores: Pau Trubat Casal
- Directores de la Tesis: Climent Molins Borrell (dir. tes.), Xavi Gironella (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2020
- Idioma: español
- Materias:
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- Resumen
In the framework of the reduction of the emissions of greenhouse gases, FOWT will be the technology that will exploit the wind resources in deep seas. In order to achieve a commercial deployment of this technology, a cost reduction is necessary through the optimization of the wind turbine by detailed studies to reduce its design uncertainties. One important aspect is the mooring system, which commonly represents between a 10 to 15 % of the capex.
The present research aims to increase the knowledge of the design and analysis of the station keeping systems for floating offshore wind turbines. One of the most important aspects for a correct analysis and design of the mooring system is the simulation of the lines coupled with the floating structure and the wind turbine.
In this dissertation, two different mooring line models coupled to a finite element model for the analysis of floating platforms are presented. The first model is a finite element model based on a slender rod approach. The model is extended to consider the rheological damping in the axial and bending direction within the constitutive equations of the problem. The second model is a new approach named quasi-dynamic model. The model assesses the static solution of the catenary equation but updates the line tension based on the external hydrodynamic forces and the inertial forces from the theoretical motion of the mooring line.
In the design of mooring lines is important to consider and foresee the different phenomena and loads that can act along on the life span of these elements. Within these phenomena, the effects of the waves forces over the mooring lines o have been studied. The study analyzes the contribution of the wave forces over the mooring lines to determine when it is an important source of damage for the fatigue strength.
Finally, new floating platform concepts need to be tested and analyzed in controlled conditions in order to validate the models used for the final designs. It is common that pool and flume basins do not present enough size for the catenary shape mooring systems because they cover a large extension. In this area, an optimization model for a truncated mooring system is presented. The truncated mooring system is formed by two types of chains to emulate the actual prototype mooring system of a scale spar platform in a narrow flume.
