Dissertations / Theses on the topic 'Éolienne offshore'
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Boujelben, Abir. "Géante éolienne offshore (GEOF) : analyse dynamique des pales flexibles en grandes transformations." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2442.
Full textIn this work, a numerical model of fluid-structure interaction is developed for dynamic analysis of giant wind turbines with flexible blades that can deflect significantly under wind loading. The model is based on an efficient partitioned FSI approach for incompressible and inviscid flow interacting with a flexible structure undergoing large transformations. It seeks to provide the best estimate of true design aerodynamic load and the associated dynamic response of such system (blades, tower, attachments, cables). To model the structure, we developed a 3D solid element to analyze geometrically nonlinear statics and dynamics of wind turbine blades undergoing large displacements and rotations. The 3D solid bending behavior is improved by introducing rotational degrees of freedom and enriching the approximation of displacement field in order to describe the flexibility of the blades more accurately. This solid iscapable of representing high frequencies modes which should be taken under control. Thus, we proposed a regularized form of the mass matrix and robust time-stepping schemes based on energy conservation and dissipation. Aerodynamic loads are modeled by using the 3D Vortex Panel Method. Such boundary method is relatively fast to calculate pressure distribution compared to CFD and provides enough precision. The aerodynamic and structural parts interact with each other via a partitioned coupling scheme with iterative procedure where special considerations are taken into account for large overall motion. In an effort to introduce a fatigue indicator within the proposed framework, pre-stressed cables are added to the wind turbine, connecting the tower to the support and providing more stability. Therefore, a novel complementary force-based finite element formulation is constructed for dynamic analysis of elasto-viscoplastic cables. Each of theproposed methods is first validated with differents estexamples.Then,several numerical simulations of full-scale wind turbines are performed in order to better understand its dynamic behavior and to eventually optimize its operation
Ikni, Djamel. "Production d’énergie marine : intégration de la production éolienne offshore dans un bouquet énergétique décentralisé." Thesis, Le Havre, 2014. http://www.theses.fr/2014LEHA0020/document.
Full textThe research work performed in this thesis is in the framework of issues related of renewable energies led by GREAH laboratory. The research work has been funded by Le Havre Municipality Assembly (CODAH). The requirements of power fluctuations in the grid are given by the grid code established by the electricity utilities companies in order to mitigate the impact of the wind power fluctuation on frequency and voltage in electrical grid. As wind energy has a fluctuating behavior, solutions have been proposed in this thesis for the situation where the power produced by an offshore wind power plant exceeds the threshold given by the grid code. Among the solutions, we can quote the ability of the wind power plant to smooth its own power production or integrate storage units. In the first case, the use of power reserve in wind turbines is possible and two methods have been proposed, and their performance evaluated. For the second solution, a methodology to find and to choose out the storage technology has been discussed. Proposals to build offshore wind farms with technologies using direct current (DC) have emerged. To get a coupling which fulfills the requirement of good reliability of power electronic devices used for the design of new wind farms, it has been proposed in this thesis adequate converters and control strategies that ensure their stability
Fichaux, Nicolas. "Évaluation du potentiel éolien offshore et imagerie satellitale." Phd thesis, École Nationale Supérieure des Mines de Paris, 2003. http://pastel.archives-ouvertes.fr/pastel-00001276.
Full textBenhamida, Mohammed Ali. "Investigation de nouvelles technologies de générateurs pour les éoliennes offshore." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMLH11/document.
Full textThe aim of this PhD report is the investigation of electrical generators dedicated to an offshore wind turbine application. The main goal is to find optimal solutions in a vast research domain containing between eight and eleven optimization variables, while respecting a the imposed constraints. In order to achieve this goal, a multi-physics model was developed allowing the determination of the electromagnetic and temperature fields distributions in the selected topologies. Lumped models coupled to the interpolation functions were chosen as a solution offering a good computation time / precision ratio, thus taking into consideration the characteristics of the materials (thermal and magnetic). The developed model was coupled to a genetic optimization algorithm, NSGAII, allowing at first; the investigation of the necessary permanent magnets weight and the active parts one of two permanent magnet synchronous generator topologies where in the first the magnets are mounted in surfaces and in the second inserted in order to have flux concentration, three different powers have been investigated 5, 8 and 15 [MW]. Second, the integration of a magnetic gear in the wind energy conversion chain was studied using the same optimal approach previously used, while comparing the weight required of permanent magnets for this type of training with that of direct drive topologies (without gearbox)
Isorna, Rocio. "Etude de l’interaction sol-structure et de la fondation d’une éolienne offshore soumise à des chargements statiques/cycliques." Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0002/document.
Full textOffshore structures are designed to resist to severe environmental loads. This manuscript presents experimental and numerical studies on offshore wind turbine pile foundations submitted to static monotonic/cyclic loads. Isolated piles (diameter of 1.8 m and embedded length of 40m) and a four-legged truss structure installed in dense Fontainebleau sand have been tested at 100×g in a geotechnical centrifuge. The behavior of the isolated piles has been characterized under monotonic axial load. The piles have been jacketed at 1×g and 100×g and the influence of the setup method on the bearing capacity has been measured. The stability diagram of a pile has been constructed using cyclic tests, CPT experiments have been performed and the influence of the initial stresses has been studied. Finally, experimental results of the jacket foundation submitted to lateral cyclic loadings are presented. The finite element method and a macro-element for piles have been used to numerically reproduce the experimental results. Constitutive laws are based on the hypoplasticity theory and the initial stresses in the soil have been calculated using the IC-05 method. The numerical results are compared with the experimental and the analytical results from the API standards
Lacaze, Jean-Baptiste. "Etude expérimentale et numérique du couplage des phénomènes aérodynamiques et hydrodynamiques sur une éolienne offshore flottante." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4735.
Full textThe present work focuses on the modeling of the hydrodynamic and aerodynamic loads on a floating wind turbine. The experimental approach took advantage of the wind and wave flume in Luminy operated by the MIO (Mediterranean Institute for Oceanography) comprising a wind tunnel with a very high flow quality blowing over a wave tank. The dimensions of the installation impose working at very small scales for which the similitudes (Reynolds, Froude) introduce high modeling complexities. This work allowed the development of numerical tools using one the one hand a frequency domain approach based on a finite element code developped by IFP¨in the early seventies, and in the other hand a time-domain approach based on Morison or Rainey formulation for hydrodynamic loads allowing the introduction of advanced methods for aerodynamic loads computation
Coudurier, Christophe. "Conception, modélisation et contrôle d'un tube anti-roulis multidirectionnel pour une barge offshore portant une éolienne." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM054/document.
Full textThanks to the recent policies of subsidizing renewables energies, constructions of offshore wind farms are booming all over the world. Yet, fixed-bottom wind turbine technology, the only one currently deployed, are too costly for deep waters. This hinders the development of wind power. This is why the scientific community has an interest in floating wind turbines (FWT). The cost of these wind turbines does not depend much on water depth. But since the wind turbine is not fixed into the seabed, the mechanical stress caused by the waves significatively raises.To reduce these detrimental loads, different approaches can be used. The litterature already discarded the control of the wind thrust applied on the rotor to compensate the "fore-aft" oscillations of the tower. We focused on stabilizing floating wind turbine by means of an attached damping system placed inside the float, it is a Tuned Liquid Column Damper (a U-tube containing a liquid, TLCD, also known as anti-roll tank), used in other areas. The damper we propose is an active system where TLCD parameters are continuously modified. Parameters are updated according to a strategy defined thanks to an analysis of the interactions between TLCD and the float (referred to as barge) supporting the wind turbine. We modelled the coupled dynamics of the barge and the TLCD in the vertical plan using a Lagrangian approach. We studied the motions of the damped system for a constant head-loss coefficient in the TLCD. The limits of this approach were detailed thanks to the classic results in double oscillators literature. Then, we focused on an active approach involving a time varying of the head-loss coefficient. We proposed Linear Quadratic Regulator and Model Predictive Control strategies to determine the head-loss coefficient. At a later stage, simulations enabled us to discard the MPC strategy as its complexity/performance ratio is rather bad compared to the LQR strategy in this particular case.A more general study of the system, in three dimensions, showed us that the TLCD is not robust against wave incidence. Therefore, we imagined and modeled new dampers inspired by the TLCD, which can damp the float effectively, regardless of the wave incidence. We named those dampers Tuned Liquid Multiple Column Damper (TLMCD).The dampers we propose are active TLMCD. Their designs are based on their dynamic properties and a cost study. We also detailed the specificities of LQR design to ensure the best possible robustness against wave incidence.The performance of the proposed TLMCD dampers was assessed through numerical simulations for a wide range of sea conditions. We observe that barge roll can be reduced by a factor of four compared to the undamped FWT. These results show us that the TLMCD we propose is interesting to damp significantly, robustly and economically our FWT
Binti, Abd Jamil Roshamida. "Optimization of the capacity factor of energy ships for far-offshore wind energy conversion using weather-routing." Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0002.
Full textThe energy ship is a relatively new concept for offshore wind energy harvesting. It consists of a windpropelled ship that generates electricity using water turbines attached underneath its hull. Since the energy ship is not grid-connected, the generated energy is stored aboard (for instance, using batteries or through conversion to hydrogen using an electrolyzer). A key advantage of the energy ship is that it is mobile. Therefore, its trajectory can be optimized using weatherrouting in order to maximize energy production, which is the focus of this thesis. The analysis in the thesis is based on numerical simulations. The weather-routing software is a modified version of QtVlm in which the optimization objective has been replaced by the maximization of the energy production. The energy ship is modelled in the software by a velocity polar and a power production polar. The wind data is based on the ECMWF ERA-5 wind dataset. The energy ship concept is particularly well-suited for the harvesting of the wind energy conversion in the faroffshore. Therefore, the capacity factor of energy ships deployed in the North-Atlantic Ocean is investigated first. Results show that a capacity factor of 70% can be (annual average). It is similar to that of floating offshore wind farms which would be deployed in the same area. Energy ships may also be used for the power supply of islands and coastal communities. Therefore, the capacity factor of energy ships deployed nearshore is also investigated. Two case studies are considered: the island of “Ile de Sein” and the “Saint-Pierre-et-Miquelon” archipelagos. Results show that the capacity factor is in the order of 50%. In this case, it would be 10 to 20% smaller than that of offshore wind farms. The weather-routing optimization depends on physical (e.g. storage capacity, rated power) and numerical parameters. Sensitivity analyses are performed in order to understand their effect on energy production. Results show that the optimization algorithm in QtVlm tends to converge to local maxima. Therefore, future work should be directed towards the development of better optimization methods
Kerner, Laura. "Interaction sol-structure sous sollicitations cycliques dynamiques : Application aux éoliennes offshore fondées sur monopieu." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1118/document.
Full textThis PhD thesis deals with the main issue which is the evolution of the first natural frequency of an offshore wind turbine. These slender structures are submitted to cyclic and dynamic loads such as wind, waves, currents, and the blade rotations. The frequencies related to these loads are close to the first natural frequency of the turbine, which lay in a narrow interval between the frequencies of the rotor and the blades. In order to avoid any resonance phenomenon, one needs a precise evaluation of not only the natural frequency of the wind turbine after its installation but also its evolution during the operation of the turbine. These two issues are considered in this work.In this context, an experimental work was developed considering two 1g physical models of an offshore wind turbine with a monopile foundation installed in Fontainebleau sand. Based on the modelling of the foundation as a set of lateral and rotational springs, an experimental program was developed in order to evaluate the stiffness of these springs and the natural frequency of the scaled models. This method was first compared to the existing methods and has allowed to develop some original methods to evaluate the natural frequency of the considered scaled model. The tests, conducted on two physical models with different scales (1/60 and 1/120), also allowed us to adapt the obtained results to a real offshore wind turbine. As a part of the study of the turbine’s evolution during its operation, cyclic load tests were conducted. A parametric study is proposed with a focus on the influence of the load’s frequency and its amplitude. The obtained results allowed us to analyze the behavior of the scaled models submitted up to one million cycles considering, mainly, the evolution of the displacement, the rotation, and the natural frequency of the structures. These results were then compared to the limits imposed by the serviceability limit state of a real offshore wind turbine
Ramachandran, Ragavendran. "Gestion des flux énergétiques d'une ferme éolienne offshore connectée à un système HVDC au travers d'un redresseur à diodes." Thesis, Ecole centrale de Lille, 2019. http://www.theses.fr/2019ECLI0015.
Full textEnergy Transition for a more sustainable world is now the priority in societies. Towards this objective, especially in Europe, the offshore wind energy development has been fast. For Offshore Wind Power Plants (OWPP) farther from the shore (50 km and beyond) Voltage Source Converter (VSC) based High Voltage DC (HVDC) Transmission has become a the prominent solution. Replacement of offshore VSC station by multiple Diode Rectifier Units (DRUs) led to a cheaper, more compact and robust solution. This thesis focusses on various technological and scientific problems involved in the control system of the Offshore Wind power Plant with Diode Rectifier (DR) based HVDC transmission. These challengess are first reviewed in detail along with the state of the art. Then, based on the system dynamics, a grid forming control scheme is proposed by using the P-V and Q-f droop relationships with a solution for the synchronization of the wind generators. Following this, some of the selected control solutions in the literature for this topology are reviewed, compared and assessed by using time domain simulations of a study case. Following this, a novel black start strategy is devised for the offshore network and a Supervisory Control is implemented for a study case by using a Discrete Event System (DES) based modeling and Supervisory Control Theory (SCT). The various faults in the offshore system are then analyzed and the above designed Grid forming control scheme is extended with Fault Ride through (FRT) capability, for offshore AC grid faults. Finally, a brief analysis is done on the challenges for the integration of this OWPP topology into a Multi Terminal DC (MTDC) network
Courbois, Adrien. "Étude expérimentale du comportement dynamique d'une éolienne offshore flottante soumise à l'action conjuguée de la houle et du vent." Phd thesis, Ecole centrale de nantes - ECN, 2013. http://tel.archives-ouvertes.fr/tel-00840511.
Full textCourbois, Adrien. "Etude expérimentale du comportement dynamique d'une éolienne offshore flottante soumise à l'action conjuguée de la houle et du vent." Ecole centrale de Nantes, 2013. https://tel.archives-ouvertes.fr/tel-00840511.
Full textBen, Ticha Mohamed Bassam. "Fusion de données satellitaires pour la cartographie du potentiel éolien offshore." Phd thesis, École Nationale Supérieure des Mines de Paris, 2007. http://tel.archives-ouvertes.fr/tel-00198912.
Full textEl, Haj Abdul Kader. "Enhanced kriging-based approaches for the probabilistic analysis of a large diameter offshore monopile in a spatially varying soil." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4036.
Full textThis thesis aims at performing a probabilistic analysis of an offshore monopile foundation embedded in a spatially varying clayey soil. The probabilistic analysis of geotechnical structures involving spatially varying soil properties is generally performed using simulation methods as the conventional Monte Carlo Simulation MCS methodology or the variance reduction techniques. These methods are not suitable for the accurate assessment of the small values of the failure probability encountered in practice when considering a computationally expensive mechanical model as is the case in this thesis. The traditional Kriging-based approach AK-MCS is an Active learning approach combining Kriging metamodeling and MCS simulation technique. Within AK-MCS, Monte Carlo simulation is performed without evaluating the whole MCS population. Indeed, the population is predicted using a Kriging meta-model which is defined on the basis of only a few points of the population, thus significantly reducing the computation time with respect to the crude MCS. Notice however that AK-MCS approach presents some issues related to (i) the strategy of selection of new training samples when performing the enrichment process of the Kriging meta-model and (ii) the corresponding stopping criterion. Three Kriging-based approaches (namely, GSAS, AK-MCSm and AK-MCSd) were developed in order to overcome these issues. GSAS is a Global sensitivity analysis-enhanced surrogate modelling approach, AK-MCSm is a multi-point enrichment approach and AK-MCSd is a Kriging-based approach that takes into account the dependency between the Kriging predictions. The proposed approaches were found to provide efficient tools for the computation of the small failure probability of complex offshore foundations within a reasonable computation time
Arnal, Vincent. "Modélisation expérimentale d'une éolienne flottante par une approche "sofware-in-the-loop"." Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0037.
Full textActual calculation tools for the multi physical numerical modeling (wind, waves, current, etc.) of a floating wind turbine need validation through experimental campaigns. The objective of this work is the development and validation of an experimental apparatus dedicated to floating wind turbines wave tank testing, focusing on the representation of wind turbine forces. A hybrid approach combining physical and numerical modeling is developed, called “software-in-the-loop” (SIL). The development of the different subsystems of an SIL system includes (i) the selection and development of the numerical model (ii) the design of the force reproduction system (actuators) and (iii) the definition of the real time environment for the integration of the numerical model, the control of actuators, and the data acquisition. To characterize and identify the performances of the SIL system, dedicated methodologies are developed. Specific test benches are built, and wave tank tests of a floating wind turbine are carried out. These wave tank tests are then compared to coupled aero-hydro-servo structure simulations to investigate the hypotheses of the hydrodynamic force model
Monjean, Pascal. "Optimisation de l'architecture et des flux énergétiques de centrales à énergies renouvelables offshore et onshore équipées de liaisons en continu." Phd thesis, Paris, ENSAM, 2012. http://pastel.archives-ouvertes.fr/pastel-00749737.
Full textLadeira, Icaro. "Développement d'un solveur rapide et fiable basé sur des formules simplifiées pour évaluer la réponse des supports tubulaires d'éoliennes offshore soumis à l 'impact d'un navire." Electronic Thesis or Diss., Ecole centrale de Nantes, 2023. http://www.theses.fr/2023ECDN0016.
Full textThis thesis focuses on thedevelopment of simplified methodologies toassess the ship collision response of offshorewind turbines (OWT) supported by standalonetubular members such as monopiles and sparfloaters, with the inclusion of elasticcontributions, and the capability to address bothlow and high-energy impactsThe research is divided into two parts. The firstpart concerns the quasi-static elasto-plasticimpact response of typical OWTs. A timesteppingalgorithm was developed based ontheoretical formulations and implemented in astructural solver that is capable of predicting theOWT’s complete deformation process.The second part examines the dynamic elasticresponse of a monopile to a ship impact. Asimplified two-step framework based ontransfer matrices was developed to assess theresponse of the OWT to a given collision load,in particular the RNA acceleration.This thesis was conducted in the framework ofthe ColFOWT project, which aims to develop acomprehensive and rapid assessment tool forship-OWT collisions. The tool will be capable ofmodelling the multi-mechanism energy transferprocess that takes place during a collisionevent, including local and global deformationmechanisms, hydrodynamic effects, andmooring response
Tekobon, Jerry. "Système multi physique de simulation pour l'étude de la production de l'énergie basée sur le couplage éolien offshore-hydrolien." Thesis, Le Havre, 2016. http://www.theses.fr/2016LEHA0031/document.
Full textThe thesis work concerns the development of a real-time emulation platform for theoretical and experimental studies of offshore wind and tidal power hybrid systems. Various energy coupling architectures are processed on the basis of the functional similarities of two systems and by both numerical and experimental emulation concepts. The notion of accelerated time used for real time simulation has been developed. The concept was validated on the experimental platform using the evolution of the mean power delivered by a small wind turbine. This approach can reduce the observation times of the measurement campaigns and could accelerate the studies for the wind potential of developing sites. We have also developed two types of coupling of the wind-tidal hybrid system. An electrical coupling based on the connection in parallel on a continuous bus of two turbines. We have developed an innovative concept of an electromechanical coupling based on the use of a single asynchronous generator on which the wind turbine and tidal turbine are simultaneously coupled. For this purpose, a vector-controlled servomotor was used to emulate the wind turbine while a synchronous motor was used as a tidal turbine emulator. The generator shaft is used as a mechanical coupling between the two systems. We have demonstrated in the experiments that we have developed the complementarity of the electrical productions of the two systems; we highlighted the need to add a storage system to compensate the simultaneous decrease of the two energy productions. The real time simulations results allow us to validate the feasibility of such a coupling
Bussolati, Federico. "Modèle multi-échelle de la fatigue des lignes d’ancrage câblées pour l’éolien offshore flottant." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN041/document.
Full textThe main function of mooring systems of floating offshore wind turbines is to ensure station keeping. The mooring lines can be composed of chains, wire ropes, synthetic ropes, or even a combination of them. In this thesis we focus on wire ropes, whose advantage over chain is to sustain high tension at a lower weight. Their design must consider the successive tension and bending loading induced by the floater movement for various wind and waves conditions.The thesis purpose is to develop a new numerical model, dedicated to the prediction of fatigue damage in mooring wire ropes of a floating wind turbine. In particular it has to simulate the relative movements between the wires when the rope is bent. Results from free-bending fatigue tests in the literature show the importance of these effects, since the first rupture is localized near the neutral plane, where fretting is more important. This phenomenon affecting the fatigue life is not considered by fatigue criteria of current offshore standards, which are related to tension-tension loading.It is worth noting that the use of a detailed model of wire rope in a fatigue design procedure represents a real challenge. The high number of contact interactions to be modeled, which are several thousands per meter of rope, and the large amount of loading cases make this type of computations extremely time-consuming.The loading used in the developed local model of wire rope is obtained from global computations performed with a dedicated multiphysics software (Deeplines). This software allows to simulate the environmental conditions (wind, waves, current) applied on the whole structural system.Some preliminary computations showed that the nonlinear bending behavior of the wire rope, linked to the wire contact interactions, does not significantly affect the output of the global model. This observation justifies the use of a top-down scheme, with a prior computation of the global scale.The global scale tension and curvature are then uniformly imposed on the central wire of the local model. The continuity of the rope is represented by periodic conditions which link the end sections to points within the model, at the same circumferential locations. The wires are modeled by beam elements. The outputs at the local scale are the stress resultants on the wires, and the contact forces and relative displacements at contact locations.Small sliding between the wires has been observed from first numerical analysis, for a representative loading case. Therefore, in order to reduce the computational cost of the wire rope model, a new node-to-node contact element has been developed, dedicated to the modeling of contact between non-parallel beams with circular cross section. It assumes fixed contact pairing and finite rotations. Numerical benchmarks and experimental tests on wire ropes show the improvement with results closer to a reference surface-to-surface model, when compared to standard algorithm for the simulation of contact between beams. Moreover, the new model reduces significantly the CPU cost and is also more robust, which is crucial for fatigue life estimates.The outputs of the local scale model are then used to obtain the complete 3D stress state by means of analytical solutions of contact between solids with cylindrical shape. Finally, a multiaxial fatigue criterion is applied in order to assess the safety of the system
Douteau, Louis. "CFD simulation with anisotropic mesh adaptation : application to floating offshore wind turbines." Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0003.
Full textThe simulation of Floating Offshore Wind Turbines (FOWTs) is a tool to help this technology reach an industrial scale. Nowadays, low-precision numerical methods are used for the dimensioning of the structures, as they involve a reduced computational effort. This PhD thesis focused on the development of highly-accurate numerical methods, with a potential to provide a thin description of the flows and efforts around FOWTs. The simulations presented in this thesis have been realized on the highly-parallelized software platform ICI-tech. A resolution of the Navier- Stokes equations in a Variational MultiScale formulation is performed using Stabilized Finite Elements. The representation of the different phases in the computational domain is achieved using immersed boundary methods. Several numerical tools have been implemented in ICItech towards an application to the simulation of FOWTs. A fluid-structure interaction paradigm has been set up, and a numerical wave tank has been defined. Verification and validation studies have been realized to assess the solver results for environmental conditions representative of those observed for operating FOWT. The accuracy achieved for both the aerodynamics at high Reynolds numbers and the propagation of wave fields has been disappointing. The influence of the anisotropic meshing on the results presented has been quantified. Several options aiming at increasing the accuracy of the simulations have been discussed
Célie, Sabrina. "Détermination des zones d'implantation d'éoliennes offshore flottantes en zone côtière Méditerranéenne à partir d'un modèle atmosphérique." Toulon, 2007. http://www.theses.fr/2007TOUL0004.
Full textThe part of the renewable energies in the French electric production should increase in a important \vay in the years to corne, encouraged in it by the policy of the European Union in protection of the environment. The most easily exploitable kind of renewable energy most easily exploitable in term of profitability and technological solutions is supplied by windmills. The maritime zones have the advantage to offer a better wind potential even for a higher cost but are rather quickly limited by the bathymetry. The floating offshore windmills will allow to increase the distances from the coast by pushing away the deep limit, with the advantage to offer a better exposure to the wind, to allow the exploitation of more powerful! wind fields and to decrease the visual impact. A climatological study is led over the last twenty years (from the data ECMWF and from the meteorological station of Marignane), to know the occurrence of the various typical meteorological situations of the Mediterranean coast (mistral, East wind. West wind, breeze of earth and sea breeze, no wind). The meteorological modelling w:ith mesoscale model RAMS 43 is used to obtain a better understanding of the climatology of the Mediterranean region and the detailed spatiotemporal structure of the wind fields in the troposphere. The attention is focus on the 10 m levels (for the interaction with the waves field) and 100 m levels (height foreseen by the axis of windmills). The modelling of the wind field in the zone of study presents various problems due to the presence of coastal zone and a very damaged topography. An adaptation of the model to the site is made by entering in the model a precise topography and vegetation. To validate the simulations, the results are compared with the experimental data measured during the campaigns of FETCH (1998), Map (1999) and DISCOUNT (2001). Then, the atmospheric modelling is used to estimate the wind potential of the region Provence-Alpes-Cote-d'Azur. Beforehand an estimation of the wind resources of the region from the parameters of Weibull is established. Then the association of the statistical analysis and the modelling completes these results by determining the fields of annual and monthly average wind potential as well as the power density of the zone. From this, the most profitable places for the exploitation of floating offshore windmills were selected
Ahayan, Sanae. "A constitutive Model for natural Clays : From Laboratory Testing to Modelling of Offshore Monopiles." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0027.
Full textNowadays, offshore wind energy industry is developing exponentially, due to the significant contribution of the North Sea wind turbines energy production to the total consumed energy in Europe. Given that the EU's energy target is to increase the share of renewable energy by 2020, there is a great potential of the offshore wind energy applications towards this direction. In order to achieve this, the support of scientific research is crucial. Monopiles have been by far the most support structure for offshore turbines, nowadays becoming applicable also for complex site conditions. The main objective of this PhD thesis is to study the soil-foundation interaction problem for offshore wind turbines monopiles embedded in clays. We focus therefore on the numerical modelling of natural clay behavior. We aim to develop a constitutive model for clay soils, which allow developing new p-y curves that could be widely applied in offshore wind turbines monopiles
Aimene, Merzak. "Services au système et gestion d'interactions énergétiques transitoires dans un parc éolien offshore." Thesis, Le Havre, 2016. http://www.theses.fr/2016LEHA0020/document.
Full textThe massive integration of intermittent production of wind energy in electrical networks creates an electrical system stability problem. Indeed, its characteristics are very different from those of conventional sources controlled by Grid managers. Therefore, the injection of this energy makes new challenges for power Grid operators. Moreover, the connection conditions are evolving and go towards the situations that all different sources participate into services of electrical systems. This thesis proposes a new nonlinear control strategy based on a « one loop flatness control » of a wind energy conversion system. This control strategy has aim of energy interactions management at the connection point through generation and tracking of reference trajectories. As all system variables are functions of the « flat output » of the system, this control provides fast response and good control in transient state. The application of this new control strategy into an offshore wind farm which is able to satisfy different connection conditions was simulated successfully. Specifically, effects of various grid faults on the proposed ancillary services (frequency and voltage regulation, and low-voltage ride through capabilities) were performed
Ech, Cheikh Fouad. "Modélisations numérique et analytique du comportement mécanique et multiphysique d'une phase haute-tension pour fermes offshores." Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0004.
Full textOTDR-based electrical cable diagnostic methods exist that allow the detection and localization of faults, but the analysis of the measured signals needs to be improved, particularly through the use of models. The link between the physical degradation of the cable and the values of the electrical parameters has, to our knowledge, never yet been realized. As a result, we are not able to know the actual condition of the cable in its natural evolution environment, let alone its residual life. The work carried out in this thesis aims at studying the mechanical behavior in both quasistatic and cyclic fatigue loadings in order to correlate the deformation levels reached to the operating mechanisms of damage and which reflect the proliferation of microstructural defects within the components of the phase (Conductor and insulators). To do this, we propose a numerical modeling using Abaqus. Then, again using numerical modeling, this time using Comsol, we tried to show the impact of mechanical damage on the physical properties (electrical and thermal) of the phase, emphasizing the role of copper. Insulators are playing a key role as well. However, the contour of the thesis had to be well defined in accordance with the time allocated and it seemed to us that a lot of information can be got out of the study of the conductor
Zhang, Haibo. "Analysis and performance enhancement of a series parallel offshore wind farm topology integrated into a HVDC grid." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10156/document.
Full textThe massive exploitation of far offshore wind energy relies heavily on the High Voltage Direct Current (HVDC) transmission system, in which dedicated offshore substations for converting power from AC into DC are necessary. However, the bulky offshore platform is costly and its installation is complicated. This thesis aims to contribute to the study of a pure DC offshore wind farm topology which exports its energy to onshore without using an offshore centralized power conversion substation. The examined wind farm topology is called Series Parallel Wind Farm (SPWF), which comprises several clusters of wind turbines connected in series, so that the output converters of the wind turbines step up the voltage to a higher level for direct power transmission. However, due to this distinctive feature, unbalanced power production of wind turbines leads to output voltage variation of wind turbines, which is harmful to the wind turbines. The work carried out in this thesis begins with the identification of the basic elements to constitute the SPWF. Afterwards, the operation of the SPWF is explained and its overvoltage characteristic is described and emphasized. An overvoltage limitation control strategy is developed, which requires an active participation of the onshore converter. Hence, the onshore Multilevel Modular Converter (MMC) as well as the HVDC cables models are examined. The control strategy is applied to both Point-to-Point (P2P) HVDC transmission system and Multi-Terminal DC (MTDC) systems. The results validate the feasibility of the proposed strategy, and demonstrate its advantage of no power curtailment requirement to limit the wind turbines output voltage
Wuillaume, Pierre-Yves. "Simulation numérique des opérations d’installation pour les fermes d’éoliennes offshore." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0003/document.
Full textOffshore wind represents the most advanced and used marine energy in the world. To increase the wind power extraction, turbines grow in size and wind farms are installed further offshore in presence of rough seas and strong winds. Marine operations become more challenging and expensive, weather windows are shorter and less frequent. This PhD work focuses on the development of a numerical tool to simulate marine operations with consistency, in particular lowering and lifting operations. The Composite-Rigid-Body Algorithm, implemented in the numerical tool InWave, is used to model multibody systems. A cable model and a winch model are developed following this multibody approach and compared to the classical low-order lumped mass theory. Hydrodynamic loads and hydrodynamic interactions are simulated using an unsteady potential flow theory based on the weakscatterer hypothesis, implemented in the numerical tool WS_CN. This approach is extended to multibody simulations and validated with comparisons to experimental data. InWave and WS_CN are coupled to solve wavestructure interaction for articulated multibody systems with large relative motions in waves. A tight coupling is selected for its robustness. The coupling equation is derived and validated from comparisons with WS_CN. This leads to the creation of a new numerical tool, InWaveS_CN, using Python as glue code language. A new mesh strategy, based on the coupling between a panel cutting method and an advance front method, is developed in WS_CN. Experiments of an upending operation were conducted at Ecole Centrale de Nantes. The comparison between the numerical simulations and the experimental data leads to a first and promising validation of InWaveS_CN
Pham, Hong-Duc. "Modélisation et Suivi en Service des Lignes d’Ancrages des Éoliennes Flottantes." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0030.
Full textIn this work a methodology for service life monitoring of mooring lines of floating wind turbines is proposed. First, an empirical expression of dynamic stiffness of a nylon rope is obtained from the testing data in the literature. A practical modeling procedure is proposed which allows accounting for the non-linear dynamic axial stiffness of nylon mooring ropes. The second part is devoted to the prediction of fatigue life of mooring lines. Cutting-edge methods for fatigue analysis in frequency domain and for simulation of nonlinear mooring response are investigated in order to perform a quick fatigue estimate and strength check in a reliability framework. The present methodology aims to support making decisions regarding maintenance or replacement of lines based on the level of reliability estimated during the expected service life
Pezy, Jean-Philippe. "Approche écosystémique d'un futur parc éolien en Manche orientale : exemple du site de Dieppe-Le Tréport." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC262.
Full textThe French government has set a target of 23% of energetic consumption derived from renewable energysources including Marine Renewable Energy for 2020. Eight offshore wind farms (OWF) are plannedalong the Atlantic-English Channel French coasts and among them Dieppe-Le Tréport site in the easternpart of the English Channel. In order to gain further knowledge on the ecosystem structure andfunctioning before the OWF installation, my PhD thesis is focused on the construction of an EcopathModel on the wind farm site in comparison with similar benthic habitats from the English Channel. Thecollection of new data on biological compartments (zooplankton, suprabenthos, meiofauna, benthos anddemersal fishes) are essential. Four cruises (summers 2014 /2015 and winters 2015 /2016) allowed toestimate the contribution of each zoological group in two main benthic habitats: i.e. sandy gravels andmedium clean sands, founded on the site (about 30 km²), corresponding to two microbenthiccommunities well represented in the English Channel. Macrofauna was sampled with a Van Veen grab,suprabenthos with a modified Macer-Giroq sledge in one station from each benthic habitat (day andnight sampling) and fish with a beam trawl in ten stations. A total of 1,584 demersal fishes has beencollected and their stomach contents has been examined. The results show the importance of largebivalves in the benthic biomass whereas the crustaceans are preferential preys of fishes. This link isdiscussed within the trophic network between consumed and non-consumed species of benthiccommunities, and the concept trophic ‘cul de sac’
Raman, Venkadesh. "A smart composite based on carbon fiber and epoxy matrix for new offshore wind-turbines. Multi-scale numerical and analytical modelings." Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0016.
Full textSmart structures have been developed as to monitor structures that have to operate in demanding industrial applications with includes harsh environments (Aeronautics and aerospace, Civil engineering, nuclear and chemical power plants…), too. Current study is focused on the suggestion of new smart composite materials that can be successfully used for wind blade structures in offshore energy generation farms. Indeed, to bring expectable energy-generation performances, new generation wind blades have to exceed 100m length, which is a hardly achievable target given that actual constitutive composite materials are based on glass-fibers, that are notably known to be very heavy and lacking stiffness. Therefore, the switch to carbon fibers (lighter and stiffer) becomes mandatory. In this thesis, we propose the implementation of a smart composite material that is based on carbon fibers and epoxy matrix (here called parent material). Fiber Optic Sensors (FOS) and Quantum-Resistive Sensors (QRS) will be used for detection of over-strained areas all over the structure. This choice is expected to enable for accurate documentation and instant sending of critical information to engineers. To achieve this goal of development of a new smart material for a critical application in offshore wind generation, we have chosen to illustrate it in a research document that is grouping several aspects, summarized in 5 chapters. The thesis is conducted using numerical and analytical modelings. The document is not having the ambition to be exhaustive. It is intended to present a pragmatic research that emphasize how areas of mechanical weakness can be diagnosed, what are the solutions that can be suggested and how we can support them, what are the issues pertaining to the use of embedded sensors and some experimental results that give appraisal of current performance status and what could be future trends
Bidaud, Pierre. "Analysis of the cyclic behavior of an adhesive in an assembly for offshore windmills applications." Thesis, Brest, 2014. http://www.theses.fr/2014BRES0119/document.
Full textEstimating capacities of adhesives to endure repetitive loadings is an essential point to perform fatigue assessments. Nevertheless, few studies have been performed on the cyclic behaviour of adhesively bonded structures. Moreover, fatigue crack initiation is less studied for adhesives than the fatigue crack propagation. Fatigue behaviour is mainly analysed using lap-shear type specimens, which are associated with complex stress states and stress concentrations. The aim of this work is to develop a predictive tool describing the cyclic behaviour of an adhesive in an assembly under fatigue loading using an experimental approach based on modified Arcan tests. Such a device is associated with low edge effects and a maximum stress state in the centre of the adhesive. Accurate experimental results under monotonic, creep and cyclic loading are presented for several load amplitudes, mean loads and loading rates. For a two-component polyurethane SikaForce®-7817 L60 MR adhesive, experimental results led to reproducible behaviour. These results underline that the evolutions of the non linear strains strongly depend on the loading type. This behaviour is well described using a visco-elastic-visco-plastic model with non-linear viscous parameters. This model, implemented in 3D finite element simulations, allows analysing the influence of viscosity. In order to limit the experimental test time the inverse identification of the model parameters is performed from modified Arcan creep-relaxation tests. The finite element simulations of bonded structures allowing an efficient description of the cyclic behaviour and using an adequate failure criterion based on the viscous strains evolutions, a validation on fatigue life predictions is performed. This work is dedicated to the study of fatigue of bonded structures in offshore windmills applications. From this strategy a fatigue life estimation of composite structures tests and on an application test is proposed
Leroy, Vincent. "Aérodynamique instationnaire pour l'analyse de la tenue à la mer des éoliennes flottantes." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0050/document.
Full textAccurate numerical simulation of thesea keeping of Floating Wind turbines (FWTs) is essential for the development of Marine Renewable Energy. State-of-the-art simulation tools assume a steady flow on the rotor. The accuracy of such models has been proven for bottom-fixed turbines, but has not been demonstrated yet for FWTs with substantial platform motions. This PhD thesis focuses on the impact of unsteady aerodynamics on the seakeeping of FWTs. This study is done by comparing quasi-steady to fully unsteady models with a coupled hydro-aerodynamic simulation tool. It shows that unsteady load shave a substantial effect on the platform motion when the rotor is highly loaded. The choice of a numerical model for example induces differences in tower base bending moments. The study also shows that state of the art quasi-steady aerodynamic models can show rather good accuracy when studying the global motion of the FWTs. Vertical Axis Wind Turbines (VAWTs) could lower infrastructure costs and are hence studied today for offshore wind projects. Unsteady aerodynamics for floating VAWT sand its effects on the sea keeping modelling have been studied during the PhD thesis,leading to similar conclusions than for traditional floating Horizontal Axis Wind Turbines (HAWTs). Those turbines have been compared to HAWTs. The study concludes that, without blade pitch control strategy, VAWTs suffer from very high wind thrust at over-rated wind speeds, leading to excessive displacements and loads. More developments are hence needed to improve the performance of such floating systems
Paniah, Crédo. "Approche multi-agents pour la gestion des fermes éoliennes offshore." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112067/document.
Full textRenewable Energy Sources (RES) has grown remarkably in last few decades. Compared to conventional energy sources, renewable generation is more available, sustainable and environment-friendly - for example, there is no greenhouse gases emission during the energy generation. However, while electrical network stability requires production and consumption equality and the electricity market constrains producers to contract future production a priori and respect their furniture commitments or pay substantial penalties, RES are mainly uncontrollable and their behavior is difficult to forecast accurately. De facto, they jeopardize the stability of the physical network and renewable producers competitiveness in the market. The Winpower project aims to design realistic, robust and stable control strategies for offshore networks connecting to the main electricity system renewable sources and controllable storage devices owned by different autonomous actors. Each actor must embed its own local physical device control strategy but a global network management mechanism, jointly decided between connected actors, should be designed as well.We assume a market participation of the actors as an unique entity (the coalition of actors connected by the Winpower network) allowing the coalition to facilitate the network management through resources aggregation, renewable producers to take advantage of controllable sources flexibility to handle market penalties risks, as well as storage devices owners to leverage their resources on the market and/or with the management of renewable imbalances. This work tackles the market participation of the coalition as a Cooperative Virtual Power Plant. For this purpose, we describe a multi-agent architecture trough the definition of intelligent agents managing and operating actors resources and the description of these agents interactions; it allows the alliance of local constraints and objectives and the global network management objective.We formalize the aggregation and planning of resources utilization as a Markov Decision Process (MDP), a formal model suited for sequential decision making in uncertain environments. Its aim is to define the sequence of actions which maximize expected actual incomes of the market participation, while decisions over controllable resources have uncertain outcomes. However, market participation decision is prior to the actual operation when renewable generation still is uncertain. Thus, the Markov Decision Process is intractable as its state in each decision time-slot is not fully observable. To solve such a Partially Observable MDP (POMDP), we decompose it into a classical MDP and an information state (a probability distribution over renewable generation errors). The Information State MDP (IS-MDP) obtained is solved with an adaptation of the Backwards Induction, a classical MDP resolution algorithm.Then, we describe a common simulation framework to compare our proposed methodology to some other strategies, including the state of the art in renewable generation market participation. Simulations results validate the resources aggregation strategy and confirm that cooperation is beneficial to renewable producers and storage devices owners when they participate in electricity market. The proposed architecture is designed to allow the distribution of the decision making between the coalition’s actors, through the implementation of a suitable coordination mechanism. We propose some distribution methodologies, to this end
Paskin, Liad. "On the interaction of fast traveling Ocean Waves and the Atmospheric Boundary Layer : A Mechanistic Approach combining Field Measurements and High-fidelity Simulations." Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0012.
Full textIn coastal areas, the wind energy industry migrates to the offshore environment, where huge spaces are still available in stronger and better behaved wind conditions. The offshore environment imposes new challenges to a well established wind energy industry. It is imperative to accurately predict and describe the offshore wind resource in order to design cost efficient solutions. The concerned flow is characterized by a turbulent Atmospheric Boundary Layer (ABL) where the ocean’s dynamics significantly alter the atmospheric flow through higher heat capacity and complex wind-wave interactions important in fairly common situations.So this Thesis reviews and extends the current knowledge regarding Wind-Wave interactions in the lower part of the Marine ABL (MABL), where they are possibly significant in the characterization of the wind resource. The MABL is investigated through physical and numerical experiments, to reveal the role of Wave Induced (WI) motions transferred from the sea into the atmosphere. Thanks to the use of complementary physical and numerical experiments, new insights on the wind-wave interaction processes are obtained
Spraul, Charles. "Suivi en service de la durée de vie des ombilicaux dynamiques pour l’éolien flottant." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0007/document.
Full textThe present work introduces a methodology to monitor fatigue damage of the dynamic power cable of a floating wind turbine. The suggested approach consists in using numerical simulations to compute the power cable response at the sea states observed on site. The quantities of interest are then obtained in any location along the cable length through the post-treatment of the simulations results. The cable has to be instrumented to quantify and to reduce the uncertainties on the calculated response of the power cable. Indeed some parameters of the numerical model should be calibrated on a regular basis in order to monitor the evolution of the cable properties that might change over time. In this context, this manuscript describes and compares various approaches to analyze the sensitivity of the power cable response to the variations of the parameters to be monitored. The purpose is to provide guidance in the choice of the instrumentation for the cable. Principal components analysis allows identifying the main modes of power cable response variations when the studied parameters are varied. Various methods are also assessed for the calibration of the monitored cable parameters. Special care is given to the quantification of the remaining uncertainty on the fatigue damage. The considered approaches are expensive to apply as they require a large number of model evaluations and as the numerical simulations durations are quite long. Surrogate models are thus employed to replace the numerical model and again different options are considered. The proposed methodology is applied to a simplified configuration which is inspired by the FLOATGEN project
Morvan, Antoine. "Impact sur le pont mouillé d’un navire SWATH pour la maintenance des éoliennes offshore." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0003.
Full textThe aim of this PhD thesis is to develop simplified models about hydrodynamic impact (slamming) on the wet deck of a SWATH vessel for the maintenance of offshore wind turbines. The knowledge of the hydrodynamic loadings that the wet deck is subjected is an essential step in the design of the vessel’s bow. To realise this study we chose a parabolic twodimensional geometry which symbolises the wet deck and a regular Airy wave for the moving free surface. The models developed are based on the Wagner theory which provides relevant results for a low computational time. Two types of impact models have been developed. So-called asymptotic models, because they use a Taylor expansion of the wave profil and non-asymptotic models because they retain the whole shape of the wave. The pressure distributions on the parabolic shape are mainly calculated by the Modified Logvinovich Model (MLM). The results in terms of wetted corrections, pressure fields and hydrodynamic loadings are compared between the two types of models as a function of the wave radius of curvature We also determine the hydrodynamic impact arrangement which produces the highest hydrodynamic loadings by using reference configurations. For non-asymptotic models, the contribution of wave amplitude and phase velocity within hydrodynamic loadings is analysed in details. For non-asymptotic models, we made the study of the spatial and time variations of pressure fields computed with the linearized Bernoulli equation. We also compared the results of composite theory (COMP) to MLM theory and their consequences on hydrodynamic loadings. Finally, in order to get a basis of comparison for these regular Airy wave impact models, we implemented a numerical model using ABAQUS/CAE software. This model is based on a Coupled Eulerian-Lagrangian (CEL) coupling and show good matching with the results of non-asymptotic models in terms of relative errors. In a design office, all those results can be used to help design of the wet deck of a SWATH vessel
Dahmani, Ouahid. "Modélisation, optimisation et analyse de fiabilité de topologies électriques AC de parcs éoliens offshore." Nantes, 2014. http://archive.bu.univ-nantes.fr/pollux/show.action?id=f600bf1d-f958-4169-862b-896e31b48209.
Full textThe aim of this thesis is to design connection topologies of AC power systems which optimize the energy efficiency of offshore wind farms with different power levels, taking into account technical constraints such as power losses, reliability and also economical aspect. First, a mono- and multi-objective optimization platform based on genetic algorithm and Prim’s algorithm was developed and tested with several objective functions. The suggested new technique of coding the network topology into a binary string enables to take into account the three parts of the electrical grid of an offshore wind farm, namely the connection among the wind turbines of the MV grid side, the locations of the offshore electrical substations and the connection map of the HV transmission system. Then, a comprehensive study is carried out on the power system reliability issues using several methods. Different electrical arrangements are analyzed according to both investment cost and energy loss in order to evaluate the effectiveness and the optimal locations of the redundant paths on the network. Three real offshore wind farms are studied, including the “Banc de Guérande” park with a capacity of 480 MW. The results prove the performance of this optimization approach and its usefulness during the planning phase of a radial or meshed electrical network in an offshore wind farm
Westerberg, Vanja. "Evaluation économique des changements des paysages littoraux : le cas du développement des parcs éoliennes dans la Mer Méditerranée." Thesis, Montpellier, SupAgro, 2012. http://www.theses.fr/2012NSAM0033/document.
Full textThe French government has committed itself to an ambitious target of boosting the offshore wind power capacity to reach 6 GW by 2020. Wind turbines onshore as well as offshore are highly contested on visual grounds. Affected stakeholders, ranging from business and property owners, fishermen and elected municipal planners, fear significant negative economic impacts on their ‘business' or their ‘property'. In the French Mediterranean region of the Languedoc Roussillon, the expectation is that the tourist industry will be chagrined in the presence of an offshore wind farm – giving a windy and cemented image of the region. Since talks began about 10 years ago, on the potential for ‘harvesting' the winds of the Mediterranean Sea, many postulates have been made with regard to the impact on coastal tourism. In particular, resistance mounted when plans to include the Languedoc Roussillon in the 2011 tender for the construction of 2 GW wind power capacity were materialising. In this light, it was considered of pertinence to investigate how offshore wind farms, installed at realistic distances from the coast (5, 8 or 12 km), would affect coastal tourism. Additionally, it was considered of interest to help define strategies that coastal community resort may adopt to boost visiting numbers or profit margins with or without wind farms. To answer these questions a full-scale choice experiment valuation survey with over 350 tourists was undertaken in the summer of 2010 on Languedoc beaches.Our survey results show (in chapter 3) that average visual disamenity costs tends to zero, when an offshore wind farm is installed somewhere between 8 and 12 km from the shore. We also find that there is considerable demand for “sustainable” coastal community resorts that favours local produce, bicycling, public transport, energy and water saving devices. Thus, our estimates show that a wind farm installed 8 km from the shore could be ‘compensated for' through the simultaneous ‘greening' of the coastal community resort. If in addition a wind farm is associated with artificial reefs and recreational user access, our results point to an actual rise in tourist related revenues when the wind farm is located min. 5 km from the coast. The policy recommendation is thus two fold: Everything else equals, a wind farm located 12 km offshore will have no negative incidence on tourism. With simultaneous application of a coherent environmental policy and wind farm associated recreational activities, wind farm siting can be conceived from 5 km and outwards.In a latter stage (chapter 5) we explicit account for the well-established fact that humans' over-estimate losses compared with equal-sized gains, in our econometric estimations. By incorporating so-called gain-loss asymmetry in the utility function, we observe that the WTP to remove wind farms had they already been installed is half the compensation required to accept their presence during a vacation. The disamenity costs associated with wind farm installation are thus of a significantly smaller magnitude had the wind farms already been installed. On the other hand, the welfare benefits associated with eco-efficiency and wind farm associated recreational activities are larger had they already been invigorated. The verdict is that asymmetry should be accounted for, or at least recognised in stated preference valuation studies that simultaneously use utility increasing and utility decreasing attributes
Huchet, Quentin. "Utilisation des méthodes de Krigeage pour le dimensionnement en fatigue des structures éoliennes posées en mer." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC074/document.
Full textThe mechanical certification of wind turbine structures is required for the funding of newoffshore projects on the French coasts. In order to ensure a maximal safety level of installations,a series of structural analyzes are required by the certification bodies. Amongst all, thedamage based computations represent an important numerical effort for EDF. The presentedworks focus on the applicability and the performances of Kriging metamodels for the estimationof the lifetime cumulated damage of offshore wind turbine structures (AK-DA approach)and the damage based reliability assessment of new designs (AK-MCS/AK-DA coupling)
Barnaud, Félix. "Influence of advanced unsteady aerodynamic models on the aeroelastic response of an offshore wind turbine." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR31.
Full textThe size of modern offshore wind turbine rotors has reached very large dimensions and keeps increasing in order to reduce the cost of electricity. More challenging designs are thus needed to improve the aerodynamic performances and reduce the structural loads. The state-of-the-art tools such as Blade Element Momentum Theory (BEMT) used to predict the loads and performances of wind turbines have been designed for much smaller rotors in standard operating conditions. Load cases in specific conditions such as yaw misalignment are a priori out of the validity range for such tools. The goal of the thesis is to investigate more advanced aerodynamic models in order to assess the differences in load predictions compared to state-of-the-art tools. In particular, this work focuses on unsteady flows which represent a challenge for engineering tools. For this purpose, a panel method code including viscous effects such as dynamic stall is compared to a BEMT code in realistic wind conditions with large yaw misalignment. The calculations are performed in the framework of aero-servo-elasto coupling in order to be represen¬tative of the load calculations performed in industry following certification standards. The impact of the dynamic stall model is investigated in particular for both BEMT and panel method, for extreme and fatigue loading in cases of yaw misalignment. Differences have been observed between both codes and for several parametrizations of dynamic stall model. In addition, it has been noticed that including the servo-elasto coupling changes a lot the observations regarding aerodynamic loading. Large angles of at¬tack are observed on wind turbine blades in yaw misalignment cases, and the flow around blade sections in such conditions is particularly affected by viscous effects such as dynamic stall or vortex shedding which are not inherently solved by panel methods nor BEMT but modeled with semi-empirical models. Alternative models such as Large Eddy Simulation (LES) that would capture these effects have to be considered. Wall-modeled LES (WMLES) is thus used in the second part of this thesis to investigate the flow around wind turbine dedicated airfoils, much thicker than airfoils used in aeronautics. Several cases are simulated, for attached and detached flows and in steady or oscillating cases. Angles of attack up to 90° are investigated at realistic Reynolds number. It appears that WMLES is able to capture correctly the main flow features in attached conditions and at very high angle of attack with coarse meshes. However, the near stall cases are more challenging to capture even with appropriate wall laws and require very fine meshes to be correctly solved. A comparison is also performed for motions with high reduced frequency and compared to other models, revealing the promising capacities of WMLES in such cases
Tiegna, Huguette. "Contribution à la modélisation analytique des machines synchrones à aimants permanents, à flux axial, à entraînement direct en vue de leur dimensionnement : application aux éoliennes." Thesis, Le Havre, 2013. http://www.theses.fr/2013LEHA0017/document.
Full textThis work deals with the search for innovative structures of generators for the offshore wind turbines reaching about ten megawatts and their design. The direct drive, axial flux, permanent magnet synchronous machines are the ones which have more energy potential for these future high power offshore wind turbines. The study of these axial flux machines required the development of a fast analytical design help tool with a good accuracy for their analysis and their design. To do so, a new approach of quasi-3D magnetic analytical modeling, which takes into account 3D effects (end effects and variations of magnets forms in the rotor) is then developed and confirmed by a 3D finite elements method. Its mathematical approach is based on the formal solution of Maxwell’s equations, in low permeability regions of the machine, by the separation of variables method. Coupled with a nodal thermal modelling and the evaluation of losses, this work succeeds in a multi-physical design tool for axial flux machines with an excellent computation time to accuracy ratio
El, Haffar Ismat. "Physical modeling and study of the behavior of deep foundations of offshore wind turbines in sand." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0021/document.
Full textThe axial and lateral capacity of piles jacked in Fontainebleau sand NE34 are studied using centrifuge modelling at 100×g. The effect of the installation method, sand density and saturation, pile diameter and pile tip geometry (open or closed-ended) and pile roughness on the axial capacity of piles are firstly studied. A significant increase in the tension capacity is observed in cyclically-jacked piles unlike piles monotonically jacked at 100×g. The saturation of dense sand accelerates plug formation during pile installation. The increase in pile roughness and sand density increases significantly the shaft resistance of the piles tested here. For all the cases, pile capacities are compared with the current design codes for offshore wind turbines. A parametric study of the effect of the installation method, load eccentricity and sand saturation on the lateral response of jacked piles is then realized using of an instrumented pile. The pile is loaded monotonically, then a thousand cycles are applied. A new methodology has been developed for determining of the constants needed in the integration procedure to identify the lateral displacement profile of the pile. The installation method influences directly the global (maximum moment and lateral displacement) and local behaviour (p-y curves) of the piles. The effect of the load eccentricity and sand saturation on the behaviour of the piles is also presented. In each case a comparison with the p-y curves extracted from the DNVGL code is realized
Jin, Zhuang. "Numerical investigation of caisson foundations in sand under combined monotonic loadings for offshore wind turbines." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0002/document.
Full textThis PhD thesis deals with the response of caisson foundations in sand for offshore wind turbines submitted to combined monotonic and cyclic loadings. First, the failure process and failure envelope (or bearing capacity diagram) of a caisson foundation in sand under combined monotonic loadings is investigated using the conventional Mohr-Coulomb constitutive model. A Combined Lagrangian-Smoothed Particle Hydrodynamics(CLSPH) method is adopted to consider large deformations and the limitations of the approach are highlighted. A recently developed critical state model for sand (SIMSAND) is then introduced and combined with the CLSPH method. Rectangular channel soil collapse tests and granular column collapse tests considering different aspect ratios are simulated to validate the approach in terms of final deposit morphologies, flow profiles and undisturbed areas.The CLSPH method and the SIMSAND model are then used to investigate the bearing capacity diagram of the caisson foundation in sand. Different parameters affecting the shape and size of the failure envelope are considered, as soil density and stiffness, friction strength, grain breakage, geometry and aspect ratio of the foundation. An analytical formula is introduced to describe the 3D failure surface reproducing the numerical results. Based on the proposed analytical formula, a macro-element for the caisson foundation in sand submitted to monotonic and cyclic loadings is finally developed within the framework of hypoplasticity. Validation is provided through comparison with experimental results
Cathelain, Marie. "Développement d’un modèle de simulation déterministe pour l’étude du couplage entre un écoulement atmosphérique et un état de mer." Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0001/document.
Full textModelling the dynamic coupling of ocean-atmosphere systems requires a fundamental and quantitative understanding of the mechanisms governing the windwave interactions: despite numerous studies, our current understanding remains quite incomplete and, in certain conditions, sparse field observations contradict the usual theoretical and stochastic models. Within the context of a growing exploitation of the offshore wind energy and the development of met ocean models, a fine description of this resource is a key issue. Field experiments and numerical modelling have revealed that atmospheric stability and wave effects, including the dynamic sea surface roughness, are two major factors affecting the wind field over oceans. A numerical tool has been implemented in order to study the coupling between an atmospheric flow and the seastate. A massively parallel large-eddy simulation developed by P. Sullivan at the National Center for Atmospheric Research is then coupled to a High-Order Spectral wave model developed at the Hydrodynamics,Energetics & Atmospheric Environment Laboratory in Ecole Centrale de Nantes. Numerous configurations of wind and sea states are investigated. It appears that, under strongly forced wind conditions above a small sea state, the semi-empirical laws referred to as standards in the international guidelines are a good approximation for the vertical profile of the mean wind speed. However, for light winds overlying fast-moving swell, the presence of a wave induced wind jet is observed, invalidating the use of such logarithmic laws
Kermagoret, Charlène. "La compensation des impacts sociaux et écologiques pour les projets d'aménagement : acceptation, perceptions et préférences des acteurs du territoire. Application au projet de parc éolien en mer de la baie de Saint-Brieuc (Bretagne,France)." Thesis, Brest, 2014. http://www.theses.fr/2014BRES0126/document.
Full textIn the context of a territory suffering from the negative impacts of an infrastructure declared of public utility, territorial compensation consists of a set of measure that aims to help maintaining the level of well-being of each and every individual as well as a desirable ecological state. This way, territorial compensation allows to balance between the global scale of the project, in which only the positive impacts are taken into account, and the local scale where both positive and negative externalities of the project are running. Initiated by a questioning on how such a public policy tool can be deployed at the heart of specific territories, the main objective of this PhD work is to characterize the expectation of local stakeholders towards the perceived impacts awaited from the instatement of a development project. More specifically, this work relies on an analytical approach centered on the study of the perception of the stakeholders of the Bay of St-Brieuc territory (Western Brittany, France), who are directly concerned by an offshore wind farm project. To reach suchaims, complementary qualitative and quantitative methods are used such as fuzzy cognitive mapping and choice experiment method. Using this kind of approaches allowed us to better define several keys for understanding how local stakeholders perceive the impacts of such a project and agree or not with compensation being an appropriate answer regarding the negative impacts of the project and consider the implementation of compensation in reference to their preferences towards different types of action – monetary incentives, public goods investments, ecological restoration. Our results show very heterogeneous perceptions in between the different stakeholders that can in a large part beexplained using the concept of Communities of Practice. Finally, when the principle of compensation is accepted by allthe stakeholders of a territory, the equivalency logical that determines the compensation expectations can be of three types: a territorial equivalency, in which the benefits of compensation must be shared by all inhabitants of the impacted territory; an ecological equivalency, in which the level of ecological functions or ecosystem services is maintained constant; and an equivalency based on economic values that must balance the loss of benefits underwent by some professional activities
Vaissière, Anne-Charlotte. "Le recours au principe de compensation écologique dans les politiques publiques en faveur de la biodiversité : enjeux organisationnels et institutionnels : cas des écosystèmes aquatiques marins et continentaux." Thesis, Brest, 2014. http://www.theses.fr/2014BRES0028/document.
Full textBiodiversity offset, as the last step of the mitigation hierarchy (avoid/reduce/offset), aims to address the current biodiversity loss crisis. The main goal of this PhD, which relies on the new institutional economics approach as a theoretical framework, is to understand the organizational and institutional issues of implementing biodiversity offsets policies for impacts on continental and offshore wetlands in Europe and the United-States. Hierarchical organizations (i.e. permittee responsible mitigation) often lead to little to no implementation of biodiversity offsets because the ecological effectiveness of case-by-case compensatory measures is unproven and the monitoring and control of numerous measures are difficult. In the United-States, the mitigation banking system aims to compensate for multiple small impacts on wetlands by carrying out restoration projects on fewer but larger wetland areas in order to reach the goal of no net loss of biodiversity. This hybrid organizational form is highly regulated and therefore stands halfway between hierarchical and market organizations. However, actors have individual and collective strategies that generate negotiations with consequences on economic development and biodiversity conservation stakes. The mitigation banking system leads to a decrease of transaction costs and a change of the actors bearing them. It seems that the evolution of the whole framework of biodiversity offsets policy implementation in the United-States leans toward an institutional complementarity between these two organizational forms rather than a disappearance of hierarchical organizations