Made available in DSpace on 2016-08-31T13:33:39Z (GMT). No. of bitstreams: 1 AdelsonML_DISSERT.pdf: 2600977 bytes, checksum: b09d306ac9269f72f993eda2576b8229 (MD5) Previous issue date: 2014-07-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Renewable energy has been essencial in power generation, among then, the wind energy arouses great attention because it is a renewable source with largely in connection with the electric power system. This connection has provided several problems to the electrical system due to electronic converters, wind variation, type of machinery. In order to reduce these problems, hybrid controllers(PI+LQR) and optimal controllers(LQR) in the inverters connected to the grid are evaluated. For the evaluation of controllers were developed mathematical models in order to perform and validate the simulations with PSIM software, the manufacturer Powersim Inc. version 9.1. The results indicate that the hybrid and optimal controllers achieved good performances when compared with a conventional type controller (PI) / As energias renováveis tem sido fundamentais na geração de energia, dentre elas a energia eólica desperta uma grande atenção, pois é uma fonte renovável com grande parte na conexão com o sistema elétrico de potência. Esta conexão tem proporcionado várias problemas ao sistema elétrico, devido aos conversores eletrônicos, variação do vento, tipo de máquinas. Com o objetivo de aliviar estes problemas, são avaliados os controladores híbrido (PI + LQR) e os controladores ótimos (LQR) nos conversores conectados à rede elétrica. Para a avaliação dos controladores foram desenvolvidos modelos matemáticos a fim de realizar e validar as simulações com o auxílio do software PSIM®, do fabricante Powersim Inc. versão 9.1. Os resultados obtidos permitem concluir que o controlador híbrido e ótimo tiveram um bom desempenho quando comparados com um controlador tipo clássico (PI)

Indiana University-Purdue University Indianapolis (IUPUI) / The harvested energy of wind can be transferred to the generators either through a gearbox or through an intermediate medium such as hydraulic fluids. In this method, high-pressure hydraulic fluids are utilized to collect the energy of single or multiple wind turbines and transfer it to a central generation unit. In this unit, the mechanical energy of the hydraulic fluid is transformed into electric energy. The prime mover of hydraulic energy transfer unit, the wind turbine, experiences the intermittent characteristics of wind. This energy variation imposes fluctuations on generator outputs and drifts their angular velocity from desired frequencies. Nonlinearities exist in hydraulic wind power transfer and are originated from discrete elements such as check valves, proportional and directional valves, and leakage factors of hydraulic pumps and motors. A thorough understanding of hydraulic wind energy transfer system requires mathematical expression of the system. This can also be used to analyze, design, and predict the behavior of large-scale hydraulic-interconnected wind power plants. This thesis introduces the mathematical modeling and controls of the hydraulic wind energy transfer system. The obtained models of hydraulic energy transfer system are experimentally validated with the results from a prototype. This research is classified into three categories. 1) A complete mathematical model of the hydraulic energy transfer system is illustrated in both ordinary differential equations and state-space representation. 2) An experimental prototype of the energy transfer system is built and used to study the behavior of the system in different operating configurations, and 3) Controllers are designed to address the problems associated with the wind speed fluctuation and reference angular velocity tracking. The mathematical models of hydraulic energy transfer system are also validated with the simulation results from a SimHydraulics Toolbox of MATLAB/Simulink®. The models are also compared with the experimental data from the system prototype. The models provided in this thesis do consider the improved assessment of the hydraulic system operation and efficiency analysis for industrial level wind power application.

Thesis (MScEng)--Stellenbosch University, 2012 / ENGLISH ABSTRACT: A technology that has advanced immeasurably as a result of the necessity for green energy production is the harnessing of wind energy. One of the most important aspects of a wind turbine is its supporting structure. The tower of a wind turbine needs to be sufficiently reliable and structurally sound to ensure that the design life of the wind turbine machine is unaffected. The tower also needs to be of the correct height to ensure that the full potential of energy capture is realised. The supporting structure of a wind turbine constitutes up to as much as 30% of the total costs of a wind turbine. The most common wind turbine supporting structures seen worldwide today are Steel Monopole Towers. The large cost proportion of the tower compels the industry to investigate the most feasible alternative supporting tower structures and thus prompted the research developed in this thesis. In this thesis the focus is on small scale wind turbines (<50kW), more specifically, a 3kW Wind Turbine. The proposed alternative design the support structures of small scale wind turbines to the presently used Steel Monopole tower was a Steel Lattice tower. Both a Steel Lattice and Steel Monopole Tower was designed for a 3kW Wind Turbine using rational design methods determined from pertinent sections of the South African design codes. The Tower designs needed to incorporate the details of the element connections, so as to encompass all of the cost parameters accurately. The foundation design of each of the towers was also required from the point of view of cost analysis completeness, and ended up playing a critical role in the feasibility analysis. To validate the design methods, the two towers were modelled in the finite element package Strand7 and a number of different analyses were performed on the two towers. The analyses included linear static, nonlinear static, natural frequency and harmonic frequency analyses. The towers were assessed for a number of different load case combinations and were examined in terms of stress states, mass participation factors and deflections, to mention a few, for the worst loading combination cases that were encountered. Once a final design was reached for both the Steel Lattice and Steel Monopole Towers, each element from which they were made was assessed from a structural viewpoint to determine manufacturing and construction costs. The cost analysis was conducted by means of asking a number of leading construction companies for unit prices for each of the identified elements to be assessed. The fabrication and construction of each of the Towers was then compared to determine which one was more feasible, in terms of each design aspect considered as well as looking at the complete end product. It was found that the Steel Lattice Tower was more feasible from the points of view of fabrication, and construction, as well as having a far more cost effective foundation. This was a positive conclusion from the perspective of the proposal for a more feasible alternative to the presently used Steel Monopole Towers. The outcome of the research conducted here could certainly prove to be worth considering from a wind farm development perspective, with particular focus on the up and coming Wind Industry developments in South Africa. / AFRIKAANSE OPSOMMING: As gevolg van die noodsaaklikheid vir die produksie van volhoubare energie is ʼn tegnologie wat met rasse skrede vooruitgegaan het die vir die benutting van windenergie. Een van die belangrikste aspekte van 'n windturbine is die ondersteunende struktuur. Die toring van 'n windturbine moet funksioneel en struktureel betroubaar wees om te verseker dat die ontwerpleeftyd van die windturbine masjien nie nadelig beïnvloed word nie. Die toring moet ook die regte hoogte wees om te verseker dat die volle potensiaal van die wind energie in meganiese energie omgesit word. Die koste van die ondersteunende struktuur van 'n windturbine verteenwoordig tot 30% van die totale koste van 'n windturbine. Die mees algemene vorm van ondersteunende strukture vir windturbines wat vandag wêreldwyd teëgekom word, is die van 'n enkel staal buisvormige toring. Die groot koste‐komponent van die toring dwing die industrie om ondersoek in te stel na die mees koste effektiewe prakties uitvoerbare alternatief vir die ondersteunende toring struktuur. Hierdie aspek van die struktuur konseptualisering het gelei tot die navorsing wat in hierdie tesis onderneem is. Die fokus van die navorsing is op klein skaal windturbines (<50kW), en meer spesifiek op 'n 3kW windturbine model. Die alternatiewe ontwerp wat ontwikkel is vir klein skaal wind turbines se ondersteunende structure, is 'n staal vakwerk toring as alternatief vir die staal buisvormige toring. Beide 'n staal vakwerk en staal buisvormige toring vir 'n 3kW wind turbine is ontwerp deur rasionele ontwerp metodes. Die toepaslike gedeeltes van die Suid‐Afrikaanse ontwerp kodes is hiervoor gebruik. Die ontwerp vir die toring moet die besonderhede van die element verbindings in ag neem en die nodige koste parameters moet akkuraat bepaal word. Die ontwerp van die fondament van elke toring is ook noodsaaklik vir die volledigheid van die koste‐ontleding en dit speel ook 'n kritieke rol in die gangbaarheid analise. Om die ontwerp metodes te bevestig, is die twee tipes torings in die eindige element pakket, Strand7, gemodelleer en 'n aantal verskillende ontledings vir die twee torings is uitgevoer. Die ontledings sluit lineêr en nie‐lineêr statiese ontledings asook natuurlike frekwensie en dinamiese ontledings onder harmoniese belastings in. Die torings is vir 'n aantal verskillende lasgevalkombinasies ondersoek en in die spannings toestande, massadeelname faktore en defleksies vir die ergste laskombinasie gevalle wat ondervind is, is geassesseer. Sodra 'n finale ontwerp vir beide die staal vakwerk en staal buisvormige toring voltooi is, is elke element beoordeel uit 'n strukturele en materiaal oogpunt om die kostes daarvan te bepaal. Die koste‐analise is baseer op data wat voorsien is deur 'n aantal vooraanstaande konstruksiemaatskappye op 'n prys per eenheid basis vir elk van die geïdentifiseerde elemente wat geassesseer moes word. Die vervaardiging en konstruksie van elke toring is dan vergelyk om te bepaal watter een die mees haalbaar is, in terme van elke toepaslike ontwerpsaspek en deur ook die volledige eindproduk te evalueer. Daar is bevind dat die staal vakwerk toring uit die oogpunt van vervaardiging en konstruksie, asook as gevolg van 'n meer koste‐effektiewe fondament, die voorkeur alternatief verteenwoordig het. Dit was 'n positiewe gevolgtrekking uit die oogpunt van die soeke na 'n ander alternatief as die buisvormige staal torings wat tans algemeen in gebruik is. Die uitkoms van hierdie navorsing verdien oorweging uit ʼn windplaas ontwikkelingsperspektief, met ʼn spesifieke fokus op die opkomende ontwikkelinge in die wind energie industrie in Suid‐Afrika.

Computational fluid dynamics (CFD) is used in this thesis to model wind and tidal stream turbines and to investigate tidal turbine fence performance. There are two primary objectives of this work. The first is to develop and validate an actuator line method for the simulation of wind and tidal turbines which applies the blade forces to the flow field without the need for a regularisation kernel. The second is to examine tidal fences using, in part, the newly developed actuator line method. A potential flow equivalence method for determining the relative velocity to the blade chord and flow angle at the rotor blades in the actuator line method is proposed and validated. Results for simulations using this method compare favourably with those from both experiments and alternative computational methods, although the present model’s results deviate from experimental results in the vicinity of the blade tips. A CFD-embedded blade element-momentum tool is used to design rotors for operation in infinitely wide tidal fences spanning a tidal channel. Rotors are designed for fences with several different blockage ratios, with those designed for high blockage flows having greater solidity than those designed for operation in fences with lower blockage. It is found that designing rotors for operational blockage conditions can significantly improve the power output achieved by a tidal fence. Improved power output for higher blockage conditions is achieved by the application of greater thrust to the flow. Actuator line simulations of short (up to 8 turbines) fences with varying intra-rotor spacing and number of rotors confirm that hydrodynamic performance of the rotors improves as the spacing is reduced and as rotors are added to a fence. The position of a rotor within the fence impacts its performance; rotors at the ends of a fence extract reduced power compared to those at the centre of the fence, particularly for tip speed ratios greater than the design tip speed ratio.

Climate change creates an imperative to develop renewable energy infrastructure, and the state of Vermont has committed to developing new renewables. However, renewables pose significant threats to natural systems because of the dramatic changes to ecosystems that occur with development. Public outcry over new developments and dissatisfaction with the current process used for siting indicate that the old regulatory process may be outdated. This thesis seeks to bridge the divide between ecology and law in renewable energy infrastructure siting. Using the state of Vermont as a case study, it suggests a new, proactive energy planning process that would use spatial analysis and public involvement to bring experts and citizens together to evaluate difficult tradeoffs and make hard choices about where to site renewables. In this thesis I use content analysis to determine which issues are important to stakeholders involved in the debate about energy siting. I then develop spatial analysis of Chittenden County to examine four metrics important to siting: generating potential, carbon storage, viewshed, and biodiversity. This spatial analysis could be applied by policy makers to evaluate tradeoffs among these four metrics. Finally, I propose a new regulatory siting process that would use stakeholder engagement and proactive planning to create "Renewable Energy Zones" where development could be fast-tracked while safeguards are in place to protect important natural resources and the public interest. A better understanding of public concern, landscape-scale spatial modeling of ecosystem services, and a new proactive energy planning process could pave the way for a more effective siting process that allows for rapid development of renewables to combat climate change and includes local voices.

Master of Arts / Department of Economics / Tracy M. Turner / This report provides a summary of the state of wind energy in the United States, the policy instruments used to encourage renewable energy and the research finding on the benefits of wind energy. It provides insight from a Texas case study, as well as international perspectives. Renewable and non-renewable energy sources are defined and compared. The report discusses the negative environmental impacts of conventional power generation, in contrast to lack of emissions from renewable power. Background information on U.S. energy consumption and climate change are provided. The primary policies used to promote renewable energy, which apply to wind power, are explained. The economic theory behind the relationship of subsidies and externalities is explained, as well as the implications that firm profit-maximization has on market outcomes. This report finds that the benefits derived from wind energy production and the promoting policies outweigh the costs associated with them.

The aim of the paper "Instalace hybridních lamp v České republice" is to reflect on the worldwide phenomenon of renewable energy and its usage in everyday life in the form of a street lighting. Hybrid lamps are particular for the combination of the wind and solar power they generate thanks to the wind turbine and photovoltaic panels they carry. In order to evaluate their possible installation in the Czech Republic the business plan is viewed from four different perspectives - technological, economic, ecological and legal.

O presente trabalho aborda em primeira instância as contribuições do direito ambiental e sua dimensão axiológica a partir do princípio de desenvolvimento sustentável, no processo de construção do modelo ambientalmente harmônico no setor elétrico. Isto segundo o viés da teoria da justiça aplicada ao direito ambiental é afirmar, identificando os elementos de justiça ambiental, a sua importância na consolidação do arcabouço normativo aplicável à energia eólica. Posteriormente efetua-se a analise da ação racional dos Estados e da sociedade internacional perante o fenômeno de mudança climática, como causa relevante a partir da qual se institucionalizam as políticas públicas que viabilizam a inserção da fonte eólica, como elemento legitimador, da ação de planejamento do setor elétrico, com o viés do tratamento dos bens comuns; para o qual se estrutura um cenário tendencial e outro cenário sustentável do recurso eólico no caso brasileiro. Nesta mesma linha se avalia a importância da supranacionalidade e a intergovernabilidade em termos de vinculação jurídica dos estados membros, com a consequente relativização do conceito de soberania e seu efeito nas integrações regionais do Mercosul e da União Europeia, e seu efeito no comportamento da energia eólica, entendida como elemento relevante da transição energética. Finalmente, revisa-se comparativamente o modelo normativo estruturado vinculante para a energia eólica na Alemanha, na França, na Espanha e na Colômbia para a fonte eólica e o grau de segurança jurídica, assim como o nível de risco regulatório, considerando a abrupta inserção de elementos competitivos para aumentar os incentivos regulatórios. / This work addresses the contribution of environmental law and its axiological dimension, beginning from the principle of sustainable development in the construction process of the harmonious environmentally model in the electrical sector. This is explained through applied justice theory to environmental law, by identifying elements of environmental justice and its relevance to the consolidation of regulatory framework applied to wind energy. Subsequently, the interaction between the states and the international community before the climate change phenomenon is analyzed as an important cause from which the public policies are institutionalized allowing the introduction of wind power as a legitimating element for planning in the electrical sector through the common goods. For this, a tendential scenario and another sustainable scenario of the wind resource in the Brazilian case are structured. In this regard, the importance of supranationalism and intergovernamentalism in terms of legal link of the member states are evaluated, with the consequent relativization of the concept of sovereignty and its effect on the regional integrations of Mercosur and the European Union and the effect on wind energy, understood it as a relevant element of energetic transition. Finally, I make a comparative review of the binding normative model for wind power generation in Germany, France, Spain and Colombia, and the degree of legal security, as well as the level of regulatory risk considering the abrupt insertion of competitive elements to have access to regulatory incentives.

A busca pelo Desenvolvimento Sustentável inclui estratégias como o maior uso de formas de energia renováveis, que tenham menores impactos no meio ambiente, que tragam benefícios sociais, como geração de empregos, desenvolvimento científico, por exemplo e que tragam benefícios econômicos, como o barateamento do acesso à energia e uma menor dependência ao petróleo, entre outros. No Brasil, a principal fonte de geração de energia elétrica é a hidráulica que precisa ser complementada a fim de garantir um fornecimento estável. Uma forma de energia que tem grande potencial de geração no Brasil é a eólica, que compõe apenas uma pequena parte da matriz energética brasileira, mas que vem ganhando destaque nos leilões, por conta de sua competitividade. No entanto, para que o setor se consolide no país, ainda há diversos desafios. O presente trabalho se propôs a compreender o setor e esses desafios. Além de colaborar para o setor e ajuda-lo com a melhora da informação e sensibilização da opinião pública sobre energias renováveis, o trabalho pode ser de grande valia para o enriquecimento da literatura relacionada, visto que ele supre uma lacuna de trabalhos acadêmicos que analisam o setor de forma tão ampla e com tais metodologias. Foi desenvolvida uma pesquisa qualitativa dividida em duas etapas. A primeira trata-se de uma análise do setor e do ambiente em que ele está inserido, na qual foram analisados aspectos político-legais, econômicos, sociais, ambientais e tecnológicos, bem como oportunidades e ameaças do setor. Em um segundo momento, a fim de complementar essa análise, foi realizada uma análise do sistema por meio da Soft System Methodology. Para as análises propostas foram coletadas informações secundárias, principalmente utilizadas na primeira parte da análise e informações primárias, coletadas por meio de uma entrevista semiestruturada, que, juntamente com as informações da primeira etapa, foi analisada na segunda etapa. Como conclusão do trabalho, foram colocadas sugestões úteis à busca de competitividade do setor. Já que a utilização de fontes de energias renováveis é importante para a busca de Desenvolvimento Sustentável e que o Brasil tem grande potencial de tornar prática essa estratégia por meio da energia eólica, percebeu-se que é necessário incentivar o setor desenvolvendo novas linhas de financiamento, investindo-se em inovação e capacitação de recursos humanos, realizando trabalhos de conscientização do público em geral e trabalhando para que se reduza as dificuldades de implantação de projetos. Isso demonstraria os esforços do país na procura por um desenvolvimento econômico e social, que leve em consideração o meio ambiente e sua sustentabilidade, o que deveria ser feito em âmbito global. / The pursuit of sustainable development includes strategies such as increasing the use of renewable forms of energy that have less impact on the environment, that bring social benefits such as employment generation, scientific development, for example and bring economic benefits, such as cheaper access to energy and less dependence on oil, among others. In Brazil the main source of electricity generation is hydro needs to be supplemented in order to ensure a steady supply. A form of energy that has great potential generation in Brazil is the wind, which makes up only a small part of the Brazilian energy matrix, but it is gaining prominence in the auction because of their competitiveness. However, for the sector to consolidate in the country, there are still many challenges. This study aimed to understand the industry and these challenges. In addition to collaborating for the sector and help it to improve information and raise public awareness about renewable energy, the work can be of great value to the enrichment of the related literature, since it fills a gap in academic papers by analyzing the industry widely and using such methodologies. A qualitative research divided in two steps was developed. The first is an analysis of the industry and his environment, in which political-legal, economic, social, environmental and technological aspects, as well as opportunities and threats in the industry were analyzed. In a second step, in order to complement this analysis, an analysis of the system via the Soft System Methodology was held. For the proposed analyzes were collected secondary information, mainly used in the first part of the analysis and primary data collected through a semi-structured interview, which, together with information from the first step, the second step was analyzed. As completion of the work, were placed in the search for useful suggestions competitiveness of the sector. As the use of renewable energy is important to the search for sustainable development and that Brazil has great potential to make practice this strategy through the use of wind enrgy, it was realized that it is necessary to encourage the industry to develop new lines of financing, by investing in innovation and training of human resources, and undertaking public awareness in general and working for reducing the difficulties of implementing projects. This would demonstrate the country\'s efforts in the search for economic and social development that takes into consideration the environment and its sustainability, what should be done globally.

Neste trabalho desenvolve-se uma análise sobre o estado da arte e tendências para projeto de geradores elétricos em turbinas eólicas offshore. A conjunção dos requerimentos de alta confiabilidade e potência, criam condições adequadas para a aplicação de máquina elétricas multifásicas nesse setor. Desta forma, optou-se por estudar as características e condições de projeto de máquinas elétricas multifásicas, simétricas ou assimétricas. Com esta finalidade, os métodos analíticos de projeto de máquinas elétricas trifásicas são revisitados e estendidos, quando necessário, para diferentes configurações multifásicas. O foco do trabalho, consiste em desenvolver e explorar temas de projeto de geradores elétricos multifásicos, síncronos de imãs permanentes, com enrolamentos distribuídos de dupla camada. Para estudo de caso, realiza-se a comparação entre o projeto de quatro topologias diferentes. Nomeadamente, compara-se o projeto de geradores de três, seis, nove e dezoito fases para turbinas eólicas offshore de 10 MW. A configuração com gerador de nove fases apresenta os melhores resultados, com densidade de torque 10,96% superior à densidade de torque desenvolvida pela máquina trifásica analisada. Por fim, a metodologia analítica desenvolvida para o projeto de máquinas elétricas multifásicas é verificada usando o método de elementos finitos bidimensional, para o gerador síncrono de imãs permanentes de nove fases. / The state of the art and future trends for offshore wind turbines were reviewed. Due to its fault-tolerant characteristic, multiphase electrical generators were identified as strong candidates to meet the power and resilience targets of the offshore wind sector. In this work, the design aspects of three-phase electrical machines are reviewed and extended to different multiphase configurations. The main focus of the work is to develop an analytical design methodology for multiphase, symmetrical and asymmetrical, synchronous generators with double-layer distributed windings. As a case study, the project of a three-phase, six-phase, nine-phase and eighteen-phase permanent magnet synchronous generators were compared for a 10MW offshore wind turbine. The best results were found for the nine-phase topology, with a torque density 10.96% higher than the torque density of the analysed three-phase machine. The developed design methodology was validated with a finite element analysis of the ninephase permanent magnet generator.