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Significant research efforts are now being directed at floating offshore wind turbines. The main challenge posed by floating wind turbines is the high construction and installation costs of the substructure, which make it too expensive for commercial exploitation in the current energy market. With the aim of achieving a cost-effective floating platform for offshore wind turbines, a new concept of a monolithic floating spar buoy is hereby presented. The monolithic concrete structure includes both the tower and the floater, built as a continuous single piece. This new concept offers a significant cost reduction during the construction phase and also while in operation, because the platform becomes almost free of maintenance during its lifetime. The main dimensions and the hydrostatic and hydrodynamic properties are presented, including a basic structural assessment of the platform to ensure its structural integrity. The construction and installation processes are presented, taking into account the special requirements of the monolithic design. Finally, a cost comparison between a steel and an equivalent concrete platform design has been performed, showing a material cost reduction larger than 60% in the case of the concrete design.

The monolithic nature of Windcrete, that sees floater, transition piece and tower as a single concrete structure, has direct impact on its potential construction process. The large-draft spar-buoy, to be fully completed in a coastal facility, requires horizontal transport that prompts construction also to be done horizontally. Then, the constraints to produce Windcrete structures are: large concrete structure built in horizontal position, preferably in a single monolithic pour with high quality standards, and this within reasonable production time if the project is considered at commercial deployment stage. In search for an appropriate solution, proposals will seek inspiration from a variety of engineering fields: mechanized tunnelling practices, farreaching adaptations of slip-forming, reinforced centrifugal concrete pipe production and even trenchless technologies such as pipe jacking will all serve as a basis to elaborate a series of tailored solutions compatible with the specific requirements of Windcrete.

The increased size and flexibility of modern multi-Megawatt wind turbines has lead to their dynamic behaviour becoming an important design consideration. The aim of this paper is to develop a semi-active control algorithm using Semi-Active Tuned Mass Dampers (STMDs) to reduce vibrations in the flapwise direction. The model developed in this study considers only the structural dynamics of the turbine and includes the coupling between the blades and tower. The algorithm developed uses a frequency tracking technique based on the Short Time Fourier Transform (STFT). This allows real-time tuning of the dampers to the dominant frequencies in the system. Numerical simulations have been carried out to study the effectiveness of the STMDs for steady and turbulent wind loading. (6 pages)

In this paper, the hypoplastic macroelement formulation proposed by [1] has been modified in order to extend its range of applicability to offshore structures subject to cyclic loads with very high number of cycles, with particular attention to fatigue phenomena and cyclic displacement accumulation. A series of FE analysis has been performed to model the soil–foundation interaction processes of a prototype of offshore wind turbine, for which the geometrical characteristic of the superstructure and foundation, the soil conditions and the predicted environmental (wave and wind) loads were known. The study, carried out in parametric form, has allowed to better understand the role played by the modified cyclic part of the macroelement model in reproducing the shake–down effects as observed in small–scale model tests.

En este proyecto se realizará el diseño de un generador síncrono de imanes permanentes y rotor exterior para ser instalado en una turbina eólica de eje horizontal. El diseño se basará en una turbina eólica disponible en el mercado, más concretamente, una turbina de la empresa Bornay. También, eléctricamente, se basará en diseñar el generador para que se adapte a un inversor disponible en el mercado, ya que, diseñar un inversor para el generador provocaría un sobrecoste. Una vez seleccionados los elementos en que se basará el diseño del generador, se establecerán unas restricciones con el objetivo de cumplir con las exigencias de la aplicación. De esta manera, durante el transcurso del proyecto, se irán calculando y analizando las características magnéticas y eléctricas que darán forma al generador síncrono, sin olvidarnos de que se ha de adaptar a una turbina eólica e inversor electrico en concreto. Así pues, se determinarán las dimensiones del generador, los materiales empleados y la configuración de características del devanado situado en el estator. Seguidamente, se realizará un modelo en 2D tanto lateral como longitudinalmente del generador diseñado para realizar un estudio de simulación con el programa de elementos finitos FEMM. De estas simulaciones se podrán extraer resultados que determinarán algunos parámetros magnéticos, como también se podrá observar el comportamiento magnético que ocurre dentro del generador en diferentes condiciones de trabajo. Conocidos todos los parámetros característicos de un generador síncrono, se realizará un análisis de los resultados obtenidos con el objetivo de comprobar que estos resultados se adaptan a la aplicación a la que va dirigida. Este análisis será bastante interesante ya que se podrá ver la evolución de la potencia entregada en función de la velocidad del viento, también se podrá ver la variación de la tensión, frecuencia e intensidad de la corriente que hay en la salida del generador y se verá el rendimiento que tendrá el generador en todo su rango de funcionamiento. Finalmente, se ideará como se realizaría el montaje del generador diseñado en la turbina eólica y se estimará el coste económico de los elementos eléctricos que componen la instalación para la generación eólica.

En el presente proyecto se diseña el proceso de fabricación de un producto. Los objetivos son estudiar y analizar las técnicas de fabricación a utilizar, calcular los tiempos de mecanizado y producción, y a su vez evaluar los costes directos e indirectos sobre la actividad. En el desarrollo de este proceso se estudian la hoja de ruta y las hojas de fase de cada una de las piezas del producto, los tiempos de corte de todas las operaciones, los tiempos en máquina para la obtención de las piezas, los tiempos de montaje, la estructura de producción interna de la fábrica, la elección de la maquinaria necesaria para su producción, entre otros. El producto utilizado para el estudio es un diseño de un prototipo de aerogenerador que forma parte de un proyecto de Mecánica de la Escuela Técnica Superior de Ingeniería Industrial de Barcelona de la Universidad Politécnica de Cataluña. Para poder situar el proyecto en una posible realidad, se considera un producto eficaz y totalmente utilitario. Así pues, en los primeros apartados del proyecto se explica el funcionamiento del producto, sus principales características y los componentes necesarios para el montaje y puesta en marcha.

The main aim of the thesis is to develop and test some design tools for the design of offshore wind turbines (OWT) resting on direct foundations on the seabed. As will be made clear in subsequent sections structural design of OWT is a complex problem and the integration of geotechnical design within the broader structural design problem can take many different forms. It is not yet clear what degree of integration of geotechnical and structural design is optimal, as the experience so far is limited and no clear consensus has yet emerged on the particular. Our objective is not to settle this issue proposing a closed methodology but rather to describe different tools that can be employed within different design approaches.

WINDCRETE: A new spar-type floating substructure made of concrete for offshore wind turbines could help move wind farms to deeper waters while providing a cost-effective and robust alternative to steel. Called Windcrete, the substructure has been developed by a small group of professors and researchers at the Polytechnic University of Catalonia in Barcelona, Spain.

Nowadays the offshore wind energy market is clearly oriented to be extended around the world. Bottom fixed solutions for supporting offshore wind turbines are useful in shallow waters which are available in a limited extent unless a continental shelf exists. Considering the Oil & Gas background knowledge, move from bottom fixed solutions to floating solutions is not a technical challenge, but the cost of each structure in terms of industry profit is currently the main issue for its commercial implementation. That point has induced huge research efforts on the topic. Recently, a new concept consisting of a monolithic concrete SPAR platform was experimentally and numerically studied in the framework of the AFOSP KIC-InnoEnergy project (Alternative Floating Platform Designs for Offshore Wind Towers using Low Cost Materials). The studies comprised a set of hydrodynamic tests performed in the CIEM wave flume facility at UPC, with a 1:100 scaled model assuming Froude similitude. The whole test campaign includes free decay tests, RAO’s determination, regular and irregular waves with and without wind mean force. For the determination of the platform RAO’s, a set of 21 regular waves trains with periods ranging from 0.8s up to 4.8s were applied. The 6 DOF motions of the platform were measured with an infrared stereoscopic vision system. In this paper, a summary of pitch and heave RAO’s tests will be presented with the main objective to calibrate and validate the accuracy of the Morison-based numerical model for floating wind turbine platforms developed at the Universitat Politècnica de Catalunya. Because the wave flume spatial constraints, both Airy and Stokes wave theories are necessary to reproduce the correct wave kinematics. The numerical model includes both theories and a comparison between them has been done, checking the validity range of each one. The simulations revealed a reasonable good agreement with the experimental results, as well with the computed RAO’s in commercial software.

A novel concept of a floating platform for supporting wind turbines (named WindCrete) has been developed at the Universitat Politècnica de Catalunya (UPC) in order to substantially reduce the capital expenditure or CAPEX for floating offshore wind turbines. The concept is based on a monolithic full concrete structure, including the tower and the floater, which also allows a significant reduction of the operating expense, or OPEX. The basics of the concept are presented in this article, including the advantages of concrete in the marine environment, the main dimensions and the hydrostatic and hydrodynamic properties of WindCrete.

Projecte realitzat en col·laboració amb l’empresa Esteyco Energía El punto de partida del presente proyecto ha sido una patente propiedad de Esteyco Energía consistente en un nuevo concepto de cimentación autoflotante para torres eólicas offshore. El objetivo principal del proyecto ha consistido en desarrollar íntegramente una solución viable del concepto expuesto en la patente.

El presente trabajo se basa en el estudio de un nuevo diseño de turbina eólica, la cual se coloca y funciona encima de una superficie fluida. Se define un modelo matemático en base a relaciones entre los parámetros de diseño y funcionamiento, teniendo como base la aerodinámica y la mecánica de fluidos. Así mismo, una vez establecido el modelo se procede al cálculo de un ejemplo de dimensiones reales, comprobando así las premisas teóricas tratadas con un cálculo específico.

L'objectiu del projecte és construir un sistema de control que mantingui una maqueta d'aerogenerador alineada amb la direcció del vent. Per tant, les tasques a completar durant la realització del treball són: dissenyar i construir la planta (maqueta d'aerogenerador i ventilador que generarà el vent); modelitzar el comportament de la planta; definir l'algoritme de control de la posició; implementar el control mitjançant un microprocessador, un servomotor de radiocontrol i uns sensors de pressió i validar les prediccions teòriques amb resultats experimentals. Dissenyar i construir la planta. Modelitzar el comportament de la planta. Disseny del sistema de control. Implementació i programació de la plata controlada. Resultats experimentals. Conclusions