Este trabalho apresenta o desenvolvimento de um sistema de controle de absorção ativa de ondas como parte integrante da implementação de um novo tanque de ensaios de estruturas oceânicas na Universidade de São Paulo. O tanque é equipado com 148 geradores de onda dispostos em todo o seu perímetro para propiciar a geração de ondas em quaisquer direções. O método de absorção de ondas implementado é baseado em filtros digitais utilizando como realimentação hidrodinâmica a leitura de sensores de nível solidários ao gerador de ondas. Foram estudados filtro recursivos e não recursivos, unidimensionais e bidimensionais. Também é apresentado um método para a análise da estabilidade do sistema de controle em malha fechada. Para avaliar o desempenho do sistema de controle de absorção foi executada uma série de experimentos com ondas regulares com direção de propagação normal ao gerador de ondas e algumas direções oblíquas. Também foram executados ensaios com ondas irregulares na direção de propagação normal ao gerador de ondas. O coeficiente de reflexão experimental obtido apresentou boa aderência aos valores teóricos, apresentado um máximo de 5,61% para um ângulo de incidência entre 0 e 45 graus na faixa de frequência de operação do tanque. Nos ensaios com ondas oblíquas foi observado o aparecimento de uma ressonância lateral de ondas com frequência mais alta que a da onda gerada, o que impossibilitou a execução de ensaios de longa duração de ondas com ângulo de incidência diferente de 0 grau. No final são apresentadas sugestões para a correção deste problema. / This work presents the development of a control system for active absorption of waves as part of the implementation of a new test tank of ocean structures at the University of São Paulo. The tank is equipped with 148 wave generators disposed around its perimeter to allow the generation of waves in all directions. The implemented method of wave absorption is based on digital filters with hydrodynamic feedback given by level sensors solidary to the wave generator. Were studied recursive and non-recursive, one-dimensional and two-dimensional filters. A method for stability analysis of the closed loop control system it is also presented. To evaluate the performance of the absorption control system, a series of experiments was performed considering regular waves with propagation direction normal to the wave generator and some oblique directions. Were also performed tests with irregular waves with propagation direction normal to the wave generator. The experimental reflection coefficient obtained showed good adherence to the theoretical values, presenting a maximum of 5.61% for an angle of incidence between 0o to 45o in the frequency range of operation of the tank. In tests with oblique waves was observed the appearance of a lateral wave resonance with highest frequency of the generated wave, prohibiting the accomplishment of long term experiments of waves with different incidence angle of 0o. At the end it is made suggestions to correct this problem.

Este trabalho apresenta o desenvolvimento de um sistema de controle de absorção ativa de ondas como parte integrante da implementação de um novo tanque de ensaios de estruturas oceânicas na Universidade de São Paulo. O tanque é equipado com 148 geradores de onda dispostos em todo o seu perímetro para propiciar a geração de ondas em quaisquer direções. O método de absorção de ondas implementado é baseado em filtros digitais utilizando como realimentação hidrodinâmica a leitura de sensores de nível solidários ao gerador de ondas. Foram estudados filtro recursivos e não recursivos, unidimensionais e bidimensionais. Também é apresentado um método para a análise da estabilidade do sistema de controle em malha fechada. Para avaliar o desempenho do sistema de controle de absorção foi executada uma série de experimentos com ondas regulares com direção de propagação normal ao gerador de ondas e algumas direções oblíquas. Também foram executados ensaios com ondas irregulares na direção de propagação normal ao gerador de ondas. O coeficiente de reflexão experimental obtido apresentou boa aderência aos valores teóricos, apresentado um máximo de 5,61% para um ângulo de incidência entre 0 e 45 graus na faixa de frequência de operação do tanque. Nos ensaios com ondas oblíquas foi observado o aparecimento de uma ressonância lateral de ondas com frequência mais alta que a da onda gerada, o que impossibilitou a execução de ensaios de longa duração de ondas com ângulo de incidência diferente de 0 grau. No final são apresentadas sugestões para a correção deste problema. / This work presents the development of a control system for active absorption of waves as part of the implementation of a new test tank of ocean structures at the University of São Paulo. The tank is equipped with 148 wave generators disposed around its perimeter to allow the generation of waves in all directions. The implemented method of wave absorption is based on digital filters with hydrodynamic feedback given by level sensors solidary to the wave generator. Were studied recursive and non-recursive, one-dimensional and two-dimensional filters. A method for stability analysis of the closed loop control system it is also presented. To evaluate the performance of the absorption control system, a series of experiments was performed considering regular waves with propagation direction normal to the wave generator and some oblique directions. Were also performed tests with irregular waves with propagation direction normal to the wave generator. The experimental reflection coefficient obtained showed good adherence to the theoretical values, presenting a maximum of 5.61% for an angle of incidence between 0o to 45o in the frequency range of operation of the tank. In tests with oblique waves was observed the appearance of a lateral wave resonance with highest frequency of the generated wave, prohibiting the accomplishment of long term experiments of waves with different incidence angle of 0o. At the end it is made suggestions to correct this problem.

Marine Renewable Energy (MRE) is a promising source of energy for the future. However, it is still under development and many challenges need to be overcome to develop competitive solutions. While the design of the station keeping system of traditional offshore oil and gas structures is driven mainly by their low frequency motions, MRE devices are installed at nearshore locations and move dynamically. Because of these criteria, MRE mooring systems require novel mooring systems and associated standards. MRE mooring standards need to take into account the highly dynamic behaviour of these systems, which can lead to large mooring loads. The nature of these loads needs to be investigated to improve the confidence in mooring design and to improve cost-effectiveness. The aim of this thesis is to develop the understanding of peak mooring loads on highly dynamic mooring systems, in particular, the environmental conditions associated with the loads. In addition, preliminary research into the response of the mooring systems to environmental conditions is presented. Both field tests and tank tests have been conducted. Field tests give insight into the behaviour of a dynamic mooring system in real sea conditions. Measuring the mooring loads and the environmental conditions - wave, and current if available – for several months, a methodology has been developed to detect peak mooring loads and identify the associated environmental conditions in order to compare them with the environmental conditions recorded throughout the field tests. The principal finding is that peak mooring loads occur for sea states with large but not always the highest significant wave height HS. The understanding of the effect of tidal conditions on peak mooring loads requires further work. A tank test of a dynamic mooring system in moderate sea states has been conducted to observe the dynamic behaviour of the mooring system. Tank tests enable detailed observations of the dynamic behaviour of a system in a well controlled environment and allow the calibration of a numerical model. The model can be used to investigate separate physical parameters. The results from this thesis will assist in the development of specific standards for MRE mooring systems. These standards are essential for the evolution of the MRE industry.

Durch Umwandlung unterschiedlichster Formen von Energie in mechanische oder elektrische Energie wird die Menschheit seit Jahrhunderten bei der Umsetzung von Arbeitsprozessen im Alltag und bei der industriellen Nutzung unterstützt. Strömende Medien wie Wasser oder Wind gelten dabei als die ältesten Energielieferanten. Im Rahmen der Dissertation wird das Konzept einer zugspannungsverankerten Plattform für Offshore Windenergieanlagen (WEA) vorgestellt, wobei neben den, für diesen Plattformtyp typischen, vertikalen auch geneigte Verankerungselemente Verwendung finden. Diese Art der Verspannung einer zugspannungsverankerten Plattform, respektive ’Tension Leg Platfrom’ (TLP) ist bisher von keiner Quelle bekannt und stellt ein Alleinstellungsmerkmal dar. Folglich sollen Untersuchungen zum dynamischen Verhalten schwimmender Gründungen für Offshore WEA, im Speziellen zu einer TLP mit vertikalen und geneigten Ankerelementen, im Rahmen dieser Arbeit erstmalig vorgestellt werden. Die Plattform ist ein modular gestaltetes Tragwerk bestehend aus großen Rohren und mit integrierten zylindrischen Auftriebskörpern. Diese erzeugen im Transportzustand der Plattform vom Hafen zum Einsatzort und im Betriebszustand innerhalb eines Windparks den nötigen Auftrieb. Infolge der speziellen Art der Verspannung werden die Bewegungen der TLP durch die, aus den Belastungen resultierenden, Seildehnungen dominiert. Damit stellte die TLP im Vergleich zu anderen schwimmenden Gründungen ein bewegungsarmes System dar. Inhalt der hier vorgelegten Arbeit sind Untersuchungen zum dynamischen Verhalten schwimmender Offshoregründungen, im speziellen einer TLP für Windenergieanlagen. Es wurden unterschiedliche Tragstrukturen für TLP-Systeme entwickelt und im Rahmen von Modellversuchen getestet. Den Kern der Arbeit bildet der Vergleich des dynamischen Tragverhaltens der unterschiedlichen Plattformen unter Berücksichtigung der geometrischen und strukturellen Randbedingungen.

Durch Umwandlung unterschiedlichster Formen von Energie in mechanische oder elektrische Energie wird die Menschheit seit Jahrhunderten bei der Umsetzung von Arbeitsprozessen im Alltag und bei der industriellen Nutzung unterstützt. Strömende Medien wie Wasser oder Wind gelten dabei als die ältesten Energielieferanten. Im Rahmen der Dissertation wird das Konzept einer zugspannungsverankerten Plattform für Offshore Windenergieanlagen (WEA) vorgestellt, wobei neben den, für diesen Plattformtyp typischen, vertikalen auch geneigte Verankerungselemente Verwendung finden. Diese Art der Verspannung einer zugspannungsverankerten Plattform, respektive ’Tension Leg Platfrom’ (TLP) ist bisher von keiner Quelle bekannt und stellt ein Alleinstellungsmerkmal dar. Folglich sollen Untersuchungen zum dynamischen Verhalten schwimmender Gründungen für Offshore WEA, im Speziellen zu einer TLP mit vertikalen und geneigten Ankerelementen, im Rahmen dieser Arbeit erstmalig vorgestellt werden. Die Plattform ist ein modular gestaltetes Tragwerk bestehend aus großen Rohren und mit integrierten zylindrischen Auftriebskörpern. Diese erzeugen im Transportzustand der Plattform vom Hafen zum Einsatzort und im Betriebszustand innerhalb eines Windparks den nötigen Auftrieb. Infolge der speziellen Art der Verspannung werden die Bewegungen der TLP durch die, aus den Belastungen resultierenden, Seildehnungen dominiert. Damit stellte die TLP im Vergleich zu anderen schwimmenden Gründungen ein bewegungsarmes System dar. Inhalt der hier vorgelegten Arbeit sind Untersuchungen zum dynamischen Verhalten schwimmender Offshoregründungen, im speziellen einer TLP für Windenergieanlagen. Es wurden unterschiedliche Tragstrukturen für TLP-Systeme entwickelt und im Rahmen von Modellversuchen getestet. Den Kern der Arbeit bildet der Vergleich des dynamischen Tragverhaltens der unterschiedlichen Plattformen unter Berücksichtigung der geometrischen und strukturellen Randbedingungen.