I denna rapport har det utförts två fallstudier från två olika vindkraftsanläggningar och med hjälp av en utarbetad modell har livscykelkostnaderna jämförts för de två fallstudierna.Resultatet visade att livscykelkostnaden per producerad kWh sjunker allteftersom den installerade effekten blir högre.Kostnadsmodellen som utarbetats och tillämpats för resultaten har visat sig ha hög verifierbarhet då resultaten har varit jämförbara med litterära studier. / In this report, conducted two case studies from two wind farms and using an elaborate model, life cycle costs compared to the two case studies.The results showed that the lifecycle cost per kWh decreases as the installed power increases.Cost model as developed and applied to generate the reported results have been generated in the results that are comparable to literary studies.

The market of wind power as a sustainable energy source is growing, both on large and small scale. Conventional large scale wind turbines normally operate in uniform areas where expected wind speeds and turbulence characteristics are well investigated and the constructional design of the wind turbines is regulated by standard classes for different external conditions. Small scale wind turbines (SWT), on the other hand, are sometimes placed in more complex environments where the turbulence conditions are rougher. A larger amount of turbulence will generate a larger amount of fatigue loadings on the construction, increasing the risk of breakdown. It is therefore of major concern to perform more measurements and further investigate the turbulence characteristics in complex environments and the effect that these will have on small wind turbine construction. Thus, turbulence is measured with sonic anemometers at two sites with complex environments; at an urban site above a rooftop in a medium sized city (Uppsala, Sweden) and above a forest in Norunda (outside Uppsala) at two heights, near the treetops (z = 33 m) defined as complex and further up (z = 97 m) defined as more uniform. The turbulence data is analyzed and the results are compared to the normal turbulence model (NTM) as it is defined for the standard SWT classes by the International Electrotechnical Commission in the International standard 61400-2: Design requirements for small wind turbines (IEC, 2006). Measurements of  minute standard deviations of longitudinal wind speed (σu) and turbulence intensity (TIu) are reported, as well as the distributions of TIu and of 10  minute mean wind speeds (um) for the different sites and stabilities. The results show that the NTM represents the turbulence at 97 m height above the forest only for light wind speeds, smaller than 10 m/s, but underestimates the turbulence for higher wind speeds.  It should also be noted that the data is scattered and contain a number of occasions with extreme values of σu and TIu. For wind speeds higher than 10 m/s the number of observations is limited but the majority of the observations are more extreme than the NTM. At the complex sites (near the treetops and the rooftop) the NTM clearly underestimates both the magnitude and rate of change of σu with increasing wind speed, although the observed wind speeds close to these rough surfaces are low so the conclusions are limited. Average TIu at 97 m height is 19 %, compared to 41 % close above forest and 43 % above rooftop. Mean values of TIu above forest are generally 10 % lower during stable conditions (z/L > 0.05) while above rooftop, the wind material is sparse and 95 % of the observations had stable stratification so no dependence on stability can be seen. From these results it can be concluded that the turbulence characteristics close above treetops is similar to those above rooftop, but that the NTM, as it is defined for the standard SWT classes, is not valid in these complex and urban terrains and need to be modified to correctly estimate the turbulence intensities, and consequently also the loadings, affecting small wind turbines located at these kinds of sites. / Marknaden för vindkraft som en förnyelsebar energikälla växer snabbt, både stor- och småskaligt. Traditionella storskaliga vindkraftverk placeras normalt på homogena platser där vindklimatet och turbulensens karaktär är ganska väl kartlagda och konstruktionsstandarden regleras av standardklasser utifrån olika externa förhållanden. Små vindkraftverk (SWT) å andra sidan placeras ofta i mer komplex eller urban miljö där turbulensen är mer intensiv. En större andel turbulens genererar större utmattningslaster på konstruktionen vilket ökar risken att vindturbinen går sönder. Det är därför av stor vikt att utföra fler mätningar och ytterligare undersöka turbulensen i komplexa miljöer och vilken effekt den kommer ha på de små vindkraftverkens konstruktion. Med anledning av detta så har turbulensdata analyserats från mätningar med sonicanemometrar. Dels på en urban plats, ovanför ett hustak i en medelstor stad (Uppsala, Sverige). Dels vanför en skog i Norunda (utanför Uppsala) på två höjder, nära trädtopparna (33 m) som anses komplex och högre upp (97 m) som anes mer homogen. Resultaten är jämförda med den normala turbulensmodellen (NTM) så som den definieras för standard SWT klasserna av International Electrotechnical Commission i International standard 61400-2: Design requirements for small wind turbines (IEC, 2006). Mätningar av 10  minuters standardavvikelse av den longitudinella vindhastigheten (σu) och turbulensintensiteten (TIu) redovisas, liksom fördelningen av TIu och 10 minuters medelvinden (um) för olika stabilitet för de olika mätplatserna. Resultaten visar att NTM är representativ på 97 m höjd endast för låga vindhastigheter, under 10 m/s, medan modellen underskattar turbulensen för högre vindhastigheter. Det bör också noteras att spridningen är stor i data och att extrema värden av σu och TIu uppmätts vid flertalet tillfällen. För vindhastigheter över 10 m/s så är antalet mätvärden begränsade, men majoriteten av mätvärdena är högre än NTM. På de komplexa mätplatserna (nära trädtopparna och ovan hustaket) så underskattar NTM avsevärt både storleken av σu och dess förändring med ökad vindhastighet på de komplexa platserna (nära trädtopparna och ovan hustaket). Dock är de observerade vindhastigheterna låga såhär nära de skrovliga ytorna så slutsatserna är begränsade. På 97 m höjd är medelvärdet av TIu 19 %, jämfört med 41 % nära trädtopparna och 43 % ovan hustak. De är generellt 10 % lägre under stabila förhållanden (z/L > 0.05)  över skog, medan ovan hustak där vindmaterialet är begränsat och 95 % av observationerna var stabilt skiktade så ses inte något stabilitetsberoende. Från dessa resultat kan slutsatserna dras att turbulensens karaktär nära trädtoppar liknar den ovan hustak, men att NTM, så som den definieras för standard SWT klasserna, inte gäller vid dessa komplexa och urbana platser och behöver modifieras för att korrekt uppskatta turbulensintensiteterna och därmed också de laster som påverkar små vindkraftverk placerade på den här typen av platser.

Technological improvements on wind energy systems with governmental supports have increased the penetration level of wind power into the grid in recent years. The high level of penetration forces the wind turbines stay connected to the grid during the disturbances in order to enhance system stability. Moreover, power system operators must revise their grid codes in parallel with these developments. This work is devoted to the modeling of variable speed wind turbines and the investigation of fault ride trough capability of the wind turbines for grid integration studies. In the thesis, detailed models of different variable speed wind turbines will be presented. Requirements of grid codes for wind power integration will also be discussed regarding active power control, reactive power control and fault ride through (FRT) capability. Investigation of the wind turbine FRT capability is the main focus of this thesis. Methods to overcome this problem for different types of wind turbines will be also explained in detail. Models of grid-connected wind turbines with doubly-fed induction generator and permanent magnet synchronous generator are implemented in the dedicated power system analysis tool PSCAD/EMTDC. With these models and computer simulations, FRT capabilities ofvariable speed wind turbines have been studied and benchmarked and the influences on the grid during the faults are discussed.

Thesis (M.S.)--James Madison University, 2009. / Includes bibliographical references.

This thesis presents novel algorithms and a revised modeling framework to evaluate residential aggregate electrical demand response performance under scenarios with limited device-state feedback. These algorithms permit the provision of balancing reserves, or the smoothing of variable renewable energy generation, via an externally supplied target trajectory. The responsive load populations utilized were home heat pumps and deferred electric vehicle charging. As fewer devices in a responsive population report their state information, the error of the demand response program increases moderately but remains below 8%. The associated error of the demand response program is minimized with responsive load populations of approximately 4500 devices; the available capacity of the demand response system scales proportionally with population size. The results indicate that demand response programs with limited device-state feedback may provide a viable option to reduce overall system costs and address privacy concerns of individuals wishing to participate in a demand response program. / Graduate

Mémoire (T.Sc.A)--Université du Québec à Chicoutimi, 1990. / Document électronique également accessible en format PDF. CaQCU

Σκοπός της παρούσας εργασίας είναι η προσομοίωση και κατακευή ηλεκτρονικού μετατροπέα ισχύος για τη σύνδεση με το ηλεκτρικό δίκτυο του υβριδικού συστήματος της ανεμογεννήτριας και των φωτοβολταϊκών πλαισίων που είναι εγκατεστημένα στο εργαστηρίο Ε.Η.Μ.Ε. / This study is about simulation and constraction of a grid connected converter which connects a photovoltaic panel and a wind turbine into the electric grid.

Η αιολική ενέργεια είναι το κλειδί για να επιτευχθεί ο στόχος της Ε.Ε. για συμμετοχή των Α.Π.Ε. στην παραγωγή ενέργειας σε ποσοστό τουλάχιστον 20% το 2020.Για το λόγο αυτό, αυτή η διπλωματική εργασία έχει σκοπό τη μελέτη των επιπτώσεων του συστήματος αιολικής ενέργειας στο σύστημα ηλεκτρικής ενέργειας.Η έρευνα επικεντρώνεται στο τμήμα των δυναμικών επιπτώσεων, που αφορά κυρίως στις μεταβολές της αέργου ισχύος και των τάσεων στους ζυγούς του συστήματος λόγω μεταβολών διαφόρων παραμέτρων όπως ο άνεμος, οι γραμμές μεταφοράς και διάφορα είδη σφαλμάτων. / The contribution of renewable sources of energy in percent at least 20% is the energy goal of E.U. in 2020.Thus, wind power is considered to be the key to the achievement of this goal.For this reason, this diploma thesis intendsto study the influences of the wind power system to the electrical power system.The research specifies in the section of the dynamic influences, which mostly includes the variations of the voltage and the reactive powe in the systems buses due to variations of variables such as the wind speed, the transmission lines and different types of fault.

Made available in DSpace on 2014-12-17T14:07:12Z (GMT). No. of bitstreams: 1 MaxdavidOC_DISSERT.pdf: 4786704 bytes, checksum: 3c7952fbe7ed29e1b8d03e70a62dab6c (MD5) Previous issue date: 2013-12-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The research and development of wind turbine blades are essential to keep pace with worldwide growth in the renewable energy sector. Although currently blades are typically produced using glass fiber reinforced composite materials, the tendency for larger size blades, particularly for offshore applications, has increased the interest on carbon fiber reinforced composites because of the potential for increased stiffness and weight reduction. In this study a model of blade designed for large generators (5 MW) was studied on a small scale. A numerical simulation was performed to determine the aerodynamic loading using a Computational Fluid Dynamics (CFD) software. Two blades were then designed and manufactured using epoxy matrix composites: one reinforced with glass fibers and the other with carbon fibers. For the structural calculations, maximum stress failure criterion was adopted. The blades were manufactured by Vacuum Assisted Resin Transfer Molding (VARTM), typical for this type of component. A weight comparison of the two blades was performed and the weight of the carbon fiber blade was approximately 45% of the weight of the fiberglass reinforced blade. Static bending tests were carried out on the blades for various percentages of the design load and deflections measurements were compared with the values obtained from finite element simulations. A good agreement was observed between the measured and calculated deflections. In summary, the results of this study confirm that the low density combined with high mechanical properties of carbon fibers are particularly attractive for the production of large size wind turbine blades / A pesquisa e desenvolvimento de p?s de aerogeradores s?o fundamentais para acompanhar o crescimento no setor de energias renov?veis em todo mundo. Apesar das p?s atualmente serem produzidas tipicamente com materiais comp?sitos refor?ados com fibras de vidro, a tend?ncia de aumento no tamanho das p?s, especialmente no setor offshore, cresce tamb?m o interesse por materiais comp?sitos refor?ados com fibras de carbono, devido ?s suas propriedades, como elevado m?dulo de elasticidade combinado com baixa densidade. Nesse trabalho um modelo de p? desenvolvido para geradores de grande porte (5 MW) foi estudado em escala reduzida. Foram realizados estudos num?ricos empregando t?cnicas de Computational Fluid Dynamics (CFD) para determinar o carregamento aerodin?mico na p?. Foram projetadas e fabricadas duas p?s com materiais comp?sitos de matriz ep?xi, sendo uma p? com refor?o de fibras de vidro e outra com fibras de carbono. Para os c?lculos estruturais, foi adotado o crit?rio de falha por tens?o m?xima. As p?s foram fabricadas pelo processo de Vacuum Assisted Resin Transfer Molding (VARTM), t?pico para este tipo de componente. Uma compara??o do peso das duas p?s foi realizada, e a p? de fibra de carbono apresentou 45% do peso da p? de fibra de vidro. Ensaios est?ticos de flex?o foram realizados nas p?s para v?rios percentuais do carregamento de projeto e as deflex?es medidas foram comparadas com os valores obtidos nas simula??es num?ricas por elementos finitos. Uma boa concord?ncia foi observada entre os valores de deflex?o medidos e calculados. Em resumo, os resultados obtidos neste trabalho confirmam que a baixa densidade combinada com elevadas propriedades mec?nicas das fibras de carbono s?o atrativas para a produ??o de p?s de aerogeradores de grande porte

O presente trabalho apresenta uma metodologia de simulação numérica de perfis aerodinâmicos bidimensionais com foco na utilização para o projeto e otimização de pás e rotores de pequenas turbinas eólicas de eixo horizontal, bem como o emprego desses métodos em simulações nas quais efeitos de alta solidez do rotor e baixos números de Reynolds são avaliados. Essa metodologia inclui geração de malhas, seleção de métodos numéricos e validação, tendo as escolhas sido guiadas pelas práticas mais bem sucedidas na simulação de perfis aerodinâmicos, e foi aplicada na simulação dos aerofólios NACA 0012, S809 e SD7062. O código comercial ANSYS Fluent foi utilizado em todas as simulações. Na simulação de aerofólios isolados a altos números de Reynolds dos perfis NACA 0012 e S809, o modelo Transition SST (γ-Reθ) apresentou resultados mais próximos a dados experimentais do que aqueles apresentados pelo modelo k-ω SST para CL e CD, além de produzir resultados para CP que mostraram boa precisão quando comparados aos mesmos dados experimentais. Resultados de CL, CD, CF e CP são apresentados para 20 diferentes condições de operação às quais o perfil SD7062 foi submetido, com números de Reynolds variando entre 25.000 e 125.000. As distribuições dos dois últimos coeficientes sobre os dorsos do aerofólio evidenciam com clareza a presença e magnitude da bolha de separação laminar. Os coeficientes de sustentação e arrasto mostram o impacto negativo da presença da bolha nessa faixa de números de Reynolds. Além disso, nos casos simulados, o arrasto aumenta em função da diminuição do Re. Um design de pá produzido com o auxílio do código de otimização SWRDC, baseado em algoritmos genéticos, é apresentado. Três seções ao longo da envergadura dessa pá foram simuladas em uma bateria de 45 simulações, sob diversas condições de operação em função de solidez, ângulo de ataque e razão de velocidade de ponta de pá. Esses resultados mostram que a bolha de separação laminar se move na direção do bordo de ataque com o aumento da solidez, do ângulo de ataque e da TSR. Além disso, distribuições do CP mostram aumento de pressão em ambos os dorsos do perfil quando submetido aos efeitos da solidez, embora esses efeitos tenham sido responsáveis por um aumento na relação CL/CD nos casos estudados. / This thesis presents a methodology of two-dimensional airfoil simulation focusing on its application on the design and optimization of blades and rotors of small horizontal axis wind turbines, and its application in a set of numerical simulations involving high rotor solidity and low-Re effects. This methodology includes grid generation, selection of numerical methods and validation, reflecting the most successful practices in airfoil simulation, and was applied in the simulation of the NACA 0012, S809 and SD7062 airfoils. The ANSYS Fluent commercial code was used in all simulations. Results for the isolated NACA 0012 and S809 airfoils at high Reynolds numbers show that the Transition SST (γ-Reθ) turbulence model produces results closer to experimental data than those yielded by the SST k-ω model for CL and CD, having also produced CP plots that show good agreement to the same experimental data. Plots of CL, CD, CF and CP for the SD7062 airfoil are presented, for simulations at 20 different operating conditions. The CF and CP distributions evidence the negative impact of the laminar separation bubble in the range of Reynolds numbers evaluated. Results show that, for Re between 25,000 and 125,000, drag increases with decreasing Re. A blade design generated using the SWRDC optimization code, based on genetic algorithms, is presented. Three sections of the resulting blade shape were selected and were tested in a set of 45 simulations, under an array of operating conditions defined by solidity, angle of attack and TSR. Results show that the laminar separation bubble moves towards the leading edge with increasing solidity, angle of attack and TSR. Furthermore, CP plots show an increase in pressure on both surfaces when the airfoil is subject to solidity effects, although these effects show an increase in the lift-to-drag ratio at the conditions evaluated.