Recent years have seen the development of wind energy conversion systems that can exploit the superior wind resource that exists at altitudes above current wind turbine technology. One class of these systems incorporates a flying wing tethered to the ground which drives a winch at ground level. The wings often resemble sports kites, being composed of a combination of fabric and stiffening elements. Such wings are subject to load dependent deformation which makes them particularly difficult to model and control. Here we apply the techniques of evolutionary robotics i.e. evolution of neural network controllers using genetic algorithms, to the task of controlling a steerable kite. We introduce a multibody kite simulation that is used in an evolutionary process in which the kite is subject to deformation. We demonstrate how discrete time recurrent neural networks that are evolved to maximise line tension fly the kite in repeated looping trajectories similar to those seen using other methods. We show that these controllers are robust to limited environmental variation but show poor generalisation and occasional failure even after extended evolution. We show that continuous time recurrent neural networks (CTRNNs) can be evolved that are capable of flying appropriate repeated trajectories even when the length of the flying lines are changing. We also show that CTRNNs can be evolved that stabilise kites with a wide range of physical attributes at a given position in the sky, and systematically add noise to the simulated task in order to maximise the transferability of the behaviour to a real world system. We demonstrate how the difficulty of the task must be increased during the evolutionary process to deal with this extreme variability in small increments. We describe the development of a real world testing platform on which the evolved neurocontrollers can be tested.

Depuis une quinzaine d'années, l'éolien s'est grandement développé en nombre d'infrastructures et en puissance unitaire mais il reste toujours confronté à un problème de disponibilité de par les nombreuses pannes d'ordre mécanique ou électrique. Le but de ces travaux consiste à concevoir, modéliser et piloter des aérogénérateurs tolérants aux défauts mécaniques et électriques. Pour cela, une structure basée sur une génératrice asynchrone hexaphasée à grand nombre de paires de pôles a été retenue. L'augmentation du nombre de pôles permet de s'affranchir ou de simplifier le multiplicateur, source des pannes mécaniques, tandis que l'utilisation d'une structure multiphasée permet de poursuivre la production d'énergie lors de la perte de phases au stator ou de bras du convertisseur. Une modélisation fine de la génératrice sur la méthode des circuits internes équivalents a été réalisée et un algorithme de calcul des paramètres à partir des données géométriques de la machine a été développé permettant d'automatiser le calcul pour n'importe quels stators et schémas de bobinage. Associé au convertisseur, ce modèle a été simulé avec succès et une commande vectorielle a également été introduite à ce schéma. Cette stratégie de contrôle permet d'adapter les matrices de transformation ainsi que les paramètres des régulateurs PI en fonction du défaut et confère une tolérance aux défauts électriques. Cette adaptation permet de réduire significativement les oscillations de puissance lors de la perte d'une ou plusieurs phases. Pour valider les théories développées et déjà simulées, des essais ont été réalisés avec succès sur un banc d'essai de 24kW, image d'une éolienne connectée au réseau / For around 15 years, wind turbines have found a wide popularity and increase in terms of number and power per unit but they have still to deal with mechanical and electrical faults. Then, the aim of this thesis is to design, model and control a wind turbine generator that is able to cope with these problems. For this, a structure based on a squirrel cage induction machine with 6 phases and 24 poles has been studied. Indeed, by increasing the number of poles, one can simplify or eliminate the gearbox that induces many faults while a multiphase structure allows electrical energy production when several stator phases or inverter legs are lost. For this, a precise model of the generator has been developed using the equivalent intern circuits and a parameters computing strategy that allows the determination of the parameters whatever the geometrical and electrical structure of the stator has been introduced. Associated to the power converter, this model has been simulated successfully and a field oriented control has also been inserted in the whole simulation scheme. This control strategy allows tuning of the transformation matrices and also PI regulators parameters as function of the fault and therefore is robust against electrical parameters changes. Indeed, the on-line adaptation lets to reduce significantly the power ripples that appear when one or more phases are lost. To validate the proposed method that have been previously simulated, the same test have been carry out successfully on a 24 kW prototype that is a picture, at scale 1/100, of a real advanced wind turbine connected to the grid

No description available.

<p>As welfare and industry production gets higher the demand for electricity increases. Almost 90 % of the electricity generated in Brazil is from renewable sources, 85 % of the renewable energy comes from hydropower. Even if Latin America has a lot of potential for wind power their installed capacity in only 1 % of the worlds total installed capacity. Lately more and more wind turbines and wind farms are appearing along Brazil’s over 7500 kilometer long coastline.</p><p>Osorio wind farm is the largest wind farm in Latin America with a total installed effect of 150 MW. In the same state, Rio Grande du Sul, a farmer has shown interest for using his property for wind power. The purpose of this project is to lay the foundation for a deeper investigation about using Aguapé farm’s property for wind power and to show the future possibilities for Brazilian wind power.</p><p>The study is made on set in Brazil, divided into two parts, one theoretical research part and one practical part with a field trip to Aguapé farm.</p><p>In 2002 The Brazilian Government launched the PROINFA program, Alternative Sources for Energy Incentive. This year, 2009, the first wind power projects auctions are held to increase the generation from renewable electricity sources. Wind power in Brazil has the highest production when the level in the hydropower dams are at the lowest, which by integrating the electrical generating wiht wind power makes it possible to save water and avoiding lack of electricity.</p><p>Aguapé farm is located between one of the worlds biggest fresh water lakes, Lagao dos Patos, and the Atlantic Ocean. The location has very good wind potential, almost like offshore because of the closeness to large areas of water. Road connections to the farm are functional in good and dry weather conditions and not far away a 138kV power line passes through. </p><p>Surrounding neighbors are positive to wind power which makes it easier with problem caused by wind turbines, for example noise. About 40 kilometers from the farm Lagoa do Peixe National Park is located. Suggestion from the Aguapé owner is to stop with the rice production, which is disturbing the park’s natural hydrological system, to use the property for wind turbines instead.</p><p>Conclusions of the study shows that the potential for wind power at Aguapé farm is excellent and that wind power at Aguapé farm will help both the owner, Lagoa do Peixe National Park and Brazil to a better future.</p>

This thesis presents a performance evaluation of a micro horizontal axis wind turbine, investigates the use of particle image velocimetry (PIV) to capture the flow field around a rotating blade and to track water droplets in the flow. The testing was done in a low speed wind tunnel in a highly blocked configuration. The turbine was instrumented to measure rotational speed of the rotor, axial thrust and power output. Wind speed of the wake was measured with a Kiel probe. Performance characteristics were calculated and compared with the manufacturer’s published data and to power predictions by axial momentum theories. The turbine was shown to perform well and the manufacturer’s published data are accurate. Axial momentum theory over-predicts power by approximately 50%. It is shown that good PIV results can be obtained using a fog machine to seed the flow. Improved illumination and optics will be required to measure 3D flow close to the blade. Water droplets can be tracked but a shadowgraphy arrangement should be used to better visualize the droplets. The droplets also affect the rotational speed of the rotor such that capturing the blade in a consistent point in the field of view is problematic.

Thesis (M.S.)--Virginia Polytechnic Institute, 1970. / Also available via the Internet.

<p>Power generation using wind turbines is a highly researched control field.</p><p>Many control designs have been proposed based on continuous-time models</p><p>like PI-control, or state observers with state feedback but without special</p><p>regard to robustness to model uncertainties. The aim of this thesis was to</p><p>design a robust digital controller for a wind turbine.</p><p>The design was based on a discrete-time model in the polynomial framework</p><p>that was derived from a continuous-time state-space model based on</p><p>data from a real plant. A digital controller was then designed by interactive</p><p>pole placement to satisfy bounds on sensitivity functions.</p><p>As a result the controller eliminates steady state errors after a step</p><p>response, gives sufficient damping by using dynamical feedback, tolerates</p><p>changes in the dynamics to account for non linear effects, and avoids feedback</p><p>of high frequency un modeled dynamics.</p>

With the great possibility of offshore wind power that can be installed in the world seas, offshore wind power is starting to get and important source of energy. The growing sizes of wind turbines and a growing distance to land, makes the choice of transmission alternative to a more important factor. The profitability of the transmission solution is affected by many parameters, like investment cost and power losses, but also by parameters like operation &amp; maintenance and lead time of the system. The study is based on a planned wind farm with a rated power of 1 200 MW and at a distance of 125 km to the connection point. Four models have been made for the transmission network with the technology of HVAC, HVDC and a hybrid of both. The simulation program used is EeFarm II, which has an interface in Matlab and Simulink. The four solutions have been compared technically, with difficulties and advantages pointed out and also economically, with the help of LCOE, NPV and IRR. Costs, power losses and availability of the wind turbines and intra array network are not included in the study. The result of the simulations implies that the HVAC solution is the most profitable with the lowest Levelized Cost of Energy and highest Net Price Value and Internal Rate of Return. The values are 25.11 €/MWh, 387.60 M€ and 15.32 % respectively. A HVDC model with just one offshore converter station, has a LCOE close to the HVAC solution, but with a more noticeable difference in NPV and IRR (25.71 €/MWh, 300.76 M€ and 14.84 % respectively). A sensitivity analysis has been done, where seven different parameters have been changed for analysing their impact on the economic result. The largest impact made was by a change in investment cost and lead times. The results imply that with a structure of the transmission network as for the models, and with similar input data, the break point where a HVDC solution is more profitable than a HVAC solution is not yet passed at a distance of 125 km from the connection point. With an evolving technology in the field of HVDC, a shorter lead time and lower investment cost could mean that a HVDC solution would be more profitable at this distance. Difficulties for a HVAC solution with more cable required, like bigger land usage and cable manufacturing as a bottle neck, could make an important factor tough while making a decision. / Med den stora potentialen hos världens hav, börjar havsbaserad vindkraft bli en betydande energikälla. Den ökande storleken på vindkraftsturbinerna tillsammans med de ökade avstånden mellan vindkraftsparkerna och land, gör att transmissionslösningen blir en mer betydelsefull komponent. Flera olika parametrar kan vara avgörande för transmissionslösningens lönsamhet, som investeringskostnad och effektförluster, men också saker som drift &amp; underhåll och projektets ledtid. Studien är baserad på en planerad vindkraftspark med en märkeffekt på 1 200 MW och på ett avstånd på 125 km till anslutningspunkten. Fyra modeller av transmissionssnätet har gjorts, där tekniken har bestått av HVAC, HVDC samt en blandning av dessa. Simuleringarna har gjort i EeFarm II, ett program baserat på Matlab och Simulink. De fyra modellerna har jämförts tekniskt, med för- och nackdelar poängterade, och även ekonomiskt med hjälp av LCOE, NPV och IRR. Kostnader, effektförluster och tillgängligheten för vindkraftsturbinerna och internnätet i vindkraftsparken är inte inkluderade i studien. Resultaten av simuleringarna visar på att HVAC-lösningen är den mest lönsamma, med lägst Levelized Cost of Energy och högst Net Price Value och Internal Rate of Return. Värdena för dessa är 25,11 €/MWh, 387,60 M€ respektive 15,32 %. En HVDC-lösning med enbart en DC-plattform och likriktarstation för hela märkeffekten, har en LCOE inte långt ifrån HVAC-lösningen, men med en lite större skillnad i NPV och IRR (25,71 €/MWh, 300,76 M€ respektive 14,84 %). För att analysera påverkan av olika parametrar på de ekonomiska mätvärdena, har en osäkerhetsanalys gjort. Den största påverkan på resultatet syntes av förändringar av investeringskostnader och ledtider. Ovanstående resultat tyder på, med transmissionslösningar enligt modellerna i detta arbete, att brytpunkten där en HVDC-lösning är mer lönsam än en HVAC-lösning inte än är passerad vid ett avstånd på 125 km till anslutningspunkten. Med en fortfarande väldigt ung teknik för HVDC, kan den ständigt utvecklande tekniken i framtiden betyda kortare ledtider och en lägre investeringskostnad för en HVDC-lösning och möjligheten att vara en mer lönsam lösning. Komplikationer med en HVAC-lösning pga den extra landkabeln, som större landanvändning och med kabeltillverkningen som en flaskhals, kan ändå göra en HVDC-lösning mer praktisk.

As international growth in wind energy steadily increases and the world gradually moves away from fossil fuels, advanced computational tools are required to produce accurate and fast predictions in wind turbine performance, and to allow efficient design cycles using advanced materials and manufacturing methods. Currently, aerostructural analysis often employs the relatively fast but inaccurate Blade Element Momentum (BEM) theory, while accurate but slower Computational Fluid Dynamics (CFD) methods are generally used for aerodynamic analysis alone.To bridge the gap between speed and accuracy, a 3D panel code, TriPan, was coupled with an advanced structural Finite Element Method (FEM) code, TACS, to perform aerostructural analysis for wind turbine blades. In addition, the framework allows the replacement of the panel solver by higher fidelity solvers to increase the accuracy of the overall aerostructural solution.

As international growth in wind energy steadily increases and the world gradually moves away from fossil fuels, advanced computational tools are required to produce accurate and fast predictions in wind turbine performance, and to allow efficient design cycles using advanced materials and manufacturing methods. Currently, aerostructural analysis often employs the relatively fast but inaccurate Blade Element Momentum (BEM) theory, while accurate but slower Computational Fluid Dynamics (CFD) methods are generally used for aerodynamic analysis alone.To bridge the gap between speed and accuracy, a 3D panel code, TriPan, was coupled with an advanced structural Finite Element Method (FEM) code, TACS, to perform aerostructural analysis for wind turbine blades. In addition, the framework allows the replacement of the panel solver by higher fidelity solvers to increase the accuracy of the overall aerostructural solution.