With environmental and policy pressure to move towards cleaner fuel sources, wind energy is a proven technology that can be successfully implemented at the utility-scale and provide clean energy to the grid. Wind energy consists of many distributed wind turbines that are paralleled and connected to inject power to one location on the transmission grid. There are real power losses and reactive power drops that must be taken into consideration for these projects for plant performance and compliance. The better the performance of each new and operating wind farm installed, the more efficiently the grid operates as well as the less greenhouse gases generated. This thesis will first review the creation of an Excel tool to perform a load flow study given inputs for a wind farm using Newton-Raphson algorithms. Next, the results of the load flow analysis will be compared to an actual operating wind farm located in Texas to review the accuracy of the scenarios. Finally, alternative design and operating states for the wind farm are proposed and cases are simulated to review the impact on wind farm energy generation and reactive power provided to the grid. Finally, preferred improvements for future design and operational considerations are provided along with future areas of research and development. / Master of Science / This thesis is focused on improvements for wind farm design and operation to help wind farms generate more clean power to the grid. The thesis involves the creation of an Excel tool which can be used to complete required grid studies for real and reactive power flows within the wind farm to the point of connection with the transmission system. This analysis helps inform the wind farm design and operation to be more effective and operate more efficiently. An operating wind farm in Texas is explained and depicted for an understanding of how utility-scale wind farms are set up. Additionally, a year of data from an operating wind farm is used to compare the Excel load flow tool to actual data and confirm it's accuracy. Alternate methods this plant could have been designed and operated are evaluated using the new tool and actual operating conditions from the plant for the year under analysis are performed to better understand and quantify possible improvements for wind farms. This thesis is less focused on the wind turbine generator (WTG) construction and operation of a single unit, but rather focused on the output from the WTG and the impact on an entire system containing many of these distributed generators and their operation to provide energy to the grid.

More and larger wind farms are planned offshore. As the most suitable build sites are limited wind farms will be constructed near to each other in so called wind farm clusters. Behind the wind turbines in these farms there is a disrupted flow of air called a wake that is characterized by reduced wind speed and increased turbulence. These individual turbine wakes combine to form a farm wake that can travel a long distance. In wind farm clusters farm to farm interaction will occur, i.e. the long distance wake from one wind farm will impact the wind conditions for other farms in the surrounding area. The thesis contains numerical studies of these long distance wakes. In this study Large Eddy Simulations (LES) using an Actuator Disc method (ACD) are used. A prescribed boundary layer is used where the wind shear is introduced using body forces. The turbulence, based on the Mann model, is introduced as fluctuating body forces upstream of the farm. A neutral atmosphere is assumed. The applied method has earlier been used for studies of wake effects inside farms but not for the longer distances needed for farm to farm interaction. Numerical studies are performed to get better knowledge about the use of this model for long distance wakes. The first study compares the simulation results with measurements behind an existing farm. Three parameter studies are thereafter setup to analyze how to best use the model. The first parameter study examines numerical and physical parameters in the model. The second one looks at the extension of the domain and turbulence as well as the characteristics of the flow far downstream. The third one gathers information on the downstream development of turbulence with different combinations of wind shear and turbulence level. The impact of placing the turbines at different distances from the turbulence plane is also studied. Finally a second study of an existing wind farm is performed and compared with a mesoscale model. The model is shown to be relevant also for studies of long distance wakes. Combining LES with a mesoscale model can be of interest.

Our alarming rate of resource exploitation and its consequences on the environment is fuelling an increase in sustainable energy production around the world. Wind power appears to be a particularly promising energy source relative to its environmental footprint, with the exception of potential negative effects of wind power on birds. Varying results from impact assessments around the world indicate that knowledge of both abiotic and biotic factors, as well as bird behavior and ecology, is required to assess the cumulative impact of any given wind farm on local bird communities. This study aims to assess the cumulative impact of a proposed wind farm on a threatened seabird, the red-throated diver (Gavia stellata), at one of its breeding "hotspots" in Sweden: the Holmöarna islands. Measurements of environmental variables in lakes on Holmöarna are combined with breeding surveys from 2012 to 2015 to assess which environmental variables may be associated with lakes that red-throated divers do or do not breed in, and which variables are correlated with breeding success. These results are combined with a literature review to assess the potential negative effects of the proposed wind farm on the breeding population on Holmöarna. The results show that average breeding success over the survey period was 0.35 fledged young per pair per year. No difference was found in environmental variables between lakes that divers had or had not bred in. Lake area/perimeter ratio and distance to the sea were significantly negatively correlated with breeding success, although distance to the sea was only significant for lakes with at least one successful breeding attempt during the survey period. Based on these correlations, 33 of a total 40 breeding lakes are shown to have relatively high area/perimeter ratios and long distances to the sea, which may pre-dispose divers breeding within them to low breeding success. These lakes are, therefore, identified as being at high-to-moderate risk of increased breeding failure if breeding success is further reduced as a result of external factors, including that of any negative impacts of the proposed wind farm. 31 of the 40 breeding lakes are also within 1 km of the proposed wind turbine sites, which may render red-throated divers breeding within them vulnerable to displacement as a result of wind farm-related disturbance. The literature review highlights the mechanisms that may determine the cumulative impact of the wind farm on red-throated divers in terms of collision mortality, habitat displacement, and barriers to movement. The strong sensitivity of red-throated divers to disturbance is considered to be the most likely driver of any negative effects of the wind farm. In this context, I thus argue the need for a precautionary approach to planning wind power developments in the vicinity of breeding red-throated diver populations.

[pt] O investimento em energias é fundamental para a manutenção do crescimento econômico. O aumento da demanda impulsiona a busca por novas fontes que sejam eficientes e renováveis. Nesse contexto, o aumento dos investimentos em energia eólica vem se expandindo em todo o mundo. Entretanto, no caso do Brasil, esses investimentos apresentam diversos fatores de risco, tanto na regulação quanto nas condições técnicas e de mercado. A Teoria de Opções Reais será utilizada como uma ferramenta para determinar o valor do projeto eólico. Essa técnica incorpora, ao valor do projeto, as incertezas inerentes ao fluxo de caixa e, principalmente, a flexibilidade da dinâmica de decisões ao longo do tempo. A metodologia proposta neste estudo é analisar o projeto imediato pelo Método tradicional (VPL) e postergado pelos métodos de opções reais: Método Binomial e Contingent Claims. Com isso, buscou-se avaliar o melhor momento para a realização de um investimento em um Parque Eólico fictício no Nordeste do Brasil, levando em consideração que o investidor pode realizar o projeto imediatamente ou esperar. / [en] Investments in energy are crucial to maintaining economic growth. The demand growth drives the search for new sources that are both efficient and renewable. In this context, investments in wind power are increasing worldwide. However, in the Brazilian case, such investments have different risk factors, such as regulatory, technical and market conditions. We will use the Real Option Theory as a tool to determine the wind project’s value. This method incorporates the uncertainties intrinsic to the cash flow, and especially the flexibility of the over time decision dynamic, in the project value. In this work, we propose a methodology that analyzes the immediate project by the traditional method (VPL) and compare it with the delayed project analyzed by the two real option variations: binomial method and Contingent Claims. Thus, we intend to assess the best moment for investing in a fictitious wind farm in the northeastern area of Brazil, considering the investor can wait or execute the project right away.

Perception of scale is important to our activity within a space and to our experience of a landscape. This presents a problem if people cannot predict or convey the scale effects of large structures proposed in a landscape, as has been the case for recent wind turbine proposals in Scotland. To address this problem, this research explored how people perceive scale and scale effects in a landscape. It took wind turbines as an example structure and analysed how different scales of windfarm create different scale effects in different landscapes, as well as how to best assess and communicate these effects. The research applied three methods to address the research questions: Landscape and Visual Impact Assessment (LVIA), which is a standard, structured process applied by professional landscape architects; experiential landscape assessment, which included semi-structured interviews with local people in addition to site assessment; and public attitude and preference study, which included Adaptive Choice-Based Conjoint analysis (ACBC). These different methods allowed the research questions to be explored in different ways, while overlapping in some aspects and providing triangulation. The research findings revealed that our perception of scale and scale effects in a landscape is influenced by numerous attributes and depends on how these are experienced together. Building upon the theoretical background, an important difference between visual scale and spatial scale was highlighted, as well as alternative ways in which scale references are made. Throughout the research, the need for clear communication was emphasised and the findings included identifying the specific words that people use to describe scale effects in the most discriminating way. This research supported other studies in finding that consultation with local people (professionals and the public) was vital to understand in sufficient depth how a landscape was perceived, experienced and valued. In addition, the innovative development of Conjoint Analysis demonstrated how this method can reveal how people judge the relative importance of different attributes that influence landscape and visual effects and, by doing so, offer new possibilities as a tool in landscape research. Building upon the general findings concerning scale, specific findings regarding the scale effects of windfarms included: greater influence of the proximity of a windfarm than size or numbers of wind turbines; greater importance for being in private and/or fixed locations that offer a sense of refuge compared to public locations and/or when moving; the importance of collective effects perceived and experienced by a community; the importance of perceived spatial separation between a viewer and a windfarm (affecting sensitivity to scale effects within open settings); and differences in how people judge the importance of horizontal scale effects compared to vertical scale effects. The research findings contribute to the knowledge and understanding of people’s perception of scale and scale effects in a landscape and they counter some common assumptions and current practice in landscape architecture. They can be applied in practice and policy to help assess scale effects, convey more clearly to people the type of scale effects and how these will affect them, and minimise the adverse scale effects of windfarms through siting and design. The thesis also identifies how to build upon these findings in the future, including recommendations for additional research, new approaches to assessment (including the use of prompt lists) and thresholds for acceptability of scale effects.

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-09-29T12:46:00Z No. of bitstreams: 1 Eduardo Stüker - 2017.pdf: 7313484 bytes, checksum: 62b33528c60c5929fa82fa9096afeeee (MD5) / Approved for entry into archive by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2017-09-29T16:25:01Z (GMT) No. of bitstreams: 1 Eduardo Stüker - 2017.pdf: 7313484 bytes, checksum: 62b33528c60c5929fa82fa9096afeeee (MD5) / Made available in DSpace on 2017-09-29T16:25:01Z (GMT). No. of bitstreams: 1 Eduardo Stüker - 2017.pdf: 7313484 bytes, checksum: 62b33528c60c5929fa82fa9096afeeee (MD5) Previous issue date: 2017-08-18 / Este trabalho tem por objetivo principal analisar a influência de um parque eólico sobre as variáveis que controlam o escoamento atmosférico na camada limite atmosférica. O período simulado foi todo o ano de 2008, utilizando duas configurações diferentes: sem parque eólico (simplesmente o modelo Weather Research and Forecasting (WRF)) e o com parque eólico (o modelo WRF com o módulo Fitch, que parametriza a influência de aerogeradores no escoamento atmosférico), ambas utilizando a parametrização de camada limite (PCL) Yonsei-University (YSU). A partir da simulação sem parque eólico é feita a validação do modelo, utilizando dados observacionais coletados em duas estações automáticas do Instituto Nacional de Meteorologia (INMET), os municípios de Alegrete-RS e Quaraí-RS. Os índices de correlação para as estações de Alegrete-RS e Quarai-RS foram de aproximadamente 80% a 85%, respectivamente. Porém, essa análise, também mostrou uma tendência de o WRF superestimar os dados observados. O parque eólico idealizado nesse trabalho possui 100 aerogeradores de 3 MW de potência com 120 m de altura e com rotor medindo 125 m de diâmetro. Os resultados indicam que e o parque geraria, no ano de 2008, 89; 1 MWh de energia elétrica, com um fator de capacidade (FC) de 29; 7%. A partir da comparação entre os resultados das simulações com as duas configurações, a influência da presença do parque eólico sobre o comportamento das variáveis que controlam o escoamento médio na atmosfera é analisado. Apesar da velocidade do vento responder de maneira adequada, a temperatura e a turbulência do escoamento próximo à superfície diminuem, apesar da parametrização utilizada para as turbinas eólicas transformar parte da energia mecânica, parte em energia na forma de calor e parte em turbulência. Uma análise da dependência da turbulência próximo à superfície, com a estabilidade vertical do escoamento indica que a turbulência que está sendo gerada pelas turbinas não está chegando até a superfície. Esse problema pode estar diretamente relacionado com a parametrização de camada limite escolhido. / The main objective of this work is to analyze the influence of a wind farm on the variables that control the atmospheric flow in the atmospheric boundary layer (ABL). The period simulated was the whole year of 2008, by using two different configurations: without wind farm (simply Weather Research and Forecasting (WRF) model) and with a wind farm (the WRF model with the module Fitch, which parameterizes the influence of the wind turbines in the atmospheric flow), both of them using the boundary layer module (PBL-module) Yonsei-University (YSU). From the simulations without the wind farm the model validation is done, with the observed data collected in two automatic stations of Instituto Nacional de Meteorologia (INMET), in Alegrete-RS e Quaraí-RS. The correlation ratio for the stations of Alegrete-RS and Quarai-Rs was, approximately, 80% a 85%, respectively. However, this analysis, also showed a tendency in the model overestimation of the observed data. The idealized wind farm, in this work, has 100 wind turbines of 3 MW of power with 120 m of height and with rotor measuring 125 m of diameter. The results show that the wind farm would generate, in 2008, 89; 1 MWh of electric energy, with a capacity factor of 29; 7%. From the comparison between the results of the simulations with both configurations, the influence of the presence of the wind farm over the behavior of the variables that control the mean flow in the atmosphere is analyzed. In spite of adequate answer of the wind velocity, the temperature and the turbulence of the flow decreases in the presence of the wind farm, although the parametrization for the wind turbines to change part of the mechanical energy of the flow part in heat and in part in turbulence. An analysis of the dependence of the turbulence, near the ground, with the vertical stability of the flow indicates that the turbulence generate by turbines does not arrive in the low levels of the atmosphere. This problem can be directly caused by the PBL-module chosen.

Layout optimization of offshore wind farms seeks to automate the design of the wind farm and the placement of wind turbines such that the proposed wind farm maximizes its potential. The optimization of an offshore wind farm layout therefore seeks to minimize the costs of the wind farm while maximizing the energy extraction while considering the effects of wakes on the resource; the electrical infrastructure required to collect the energy generated; the cost variation across the site; and all technical and consenting constraints that the wind farm developer must adhere to. As wakes, electrical losses, and costs are non-linear, this produces a complex optimization problem. This thesis describes the design, development, validation, and initial application of a new framework for the optimization of offshore wind farm layouts using either a genetic algorithm or a particle swarm optimizer. The developed methodology and analysis tool have been developed such that individual components can either be used to analyze a particular wind farm layout or used in conjunction with the optimization algorithms to design and optimize wind farm layouts. To accomplish this, separate modules have been developed and validated for the design and optimization of the necessary electrical infrastructure, the assessment of the energy production considering energy losses, and the estimation of the project costs. By including site-dependent parameters and project specific constraints, the framework is capable of exploring the influence the wind farm layout has on the levelized cost of energy of the project. Deploying the integrated framework using two common engineering metaheuristic algorithms to hypothetical, existing, and future wind farms highlights the advantages of this holistic layout optimization framework over the industry standard approaches commonly deployed in offshore wind farm design leading to a reduction in LCOE. Application of the tool to a UK Round 3 site recently under development has also highlighted how the use of this tool can aid in the development of future regulations by considering various constraints on the placement of wind turbines within the site and exploring how these impact the levelized cost of energy.

<p>There often exist hard-to-identify or unforeseen external parties that emerge as indirect stakeholders of a project who can significantly influence its execution and outcome. The broader stakeholder landscape in both theory and practice recognizes the local community including other interest groups of a project site as such key stakeholders. However recent cases have revealed shortcomings in managing this category of stakeholders, leading to authoritative rejection of development permit applications and strong local opposition that consequently increase costs and delay to the project. There is indication that a weak community stakeholder management process in the planning stages can cause problems to the project, or worse, in some cases lead to project failure and abandonment by the developer. Wind energy development projects are not exempted from this condition and are possibly even more prone as they involve the erection of tall wind turbines across wide-open landscapes that are deemed controversial and unacceptable to a wider population. Endorsed by the persuasive rationale for wind energy especially in view of the environment and sustainable development, a more comprehensive and effective guidance for community stakeholder management in the planning stage is required to mitigate, if not eliminate, potential issues that can hinder the successful implementation of wind energy development projects. Hence this thesis primarily seeks to answer the research question of: “How should community stakeholders of wind energy development projects be managed in the planning stage prior to permit application?”.</p><p>Using a qualitative approach to research through interviews with several industry practitioners and reviewing secondary data of industry best practices, policies, literature and case studies, 16 community stakeholder management key conclusion points could be made from research data collected. These points are individually important while in aggregate form a broad and novel framework that serves to further raise the awareness and readiness of wind energy development project managers in their community stakeholder management initiatives. A baseline list of community stakeholders and their common concerns were identified, together with suggested approaches to identify community stakeholders in each project. Community consultation is key to the process and engaging the community as widely and early as possible is recommended. Furthermore, key principles and an array of common methods for community stakeholder management in the planning stages of the project are presented, while acknowledging that not all stakeholders can be satisfied at each instance. Ultimately these findings were consolidated in a community consultation checklist that serves as a more systematic and practical tool in guiding project managers in their community stakeholder management initiatives during planning.</p><p>The research findings herewith contribute valuable insights to the existing body of knowledge in this area and also provide enhanced practical guidance to project managers in achieving successful community stakeholder management during planning, facilitating higher acceptance for the proposal, carrying out a more efficient and effective planning process and improving the likelihood for project approval from both authoritative and judiciary standpoints.</p>

There often exist hard-to-identify or unforeseen external parties that emerge as indirect stakeholders of a project who can significantly influence its execution and outcome. The broader stakeholder landscape in both theory and practice recognizes the local community including other interest groups of a project site as such key stakeholders. However recent cases have revealed shortcomings in managing this category of stakeholders, leading to authoritative rejection of development permit applications and strong local opposition that consequently increase costs and delay to the project. There is indication that a weak community stakeholder management process in the planning stages can cause problems to the project, or worse, in some cases lead to project failure and abandonment by the developer. Wind energy development projects are not exempted from this condition and are possibly even more prone as they involve the erection of tall wind turbines across wide-open landscapes that are deemed controversial and unacceptable to a wider population. Endorsed by the persuasive rationale for wind energy especially in view of the environment and sustainable development, a more comprehensive and effective guidance for community stakeholder management in the planning stage is required to mitigate, if not eliminate, potential issues that can hinder the successful implementation of wind energy development projects. Hence this thesis primarily seeks to answer the research question of: “How should community stakeholders of wind energy development projects be managed in the planning stage prior to permit application?”. Using a qualitative approach to research through interviews with several industry practitioners and reviewing secondary data of industry best practices, policies, literature and case studies, 16 community stakeholder management key conclusion points could be made from research data collected. These points are individually important while in aggregate form a broad and novel framework that serves to further raise the awareness and readiness of wind energy development project managers in their community stakeholder management initiatives. A baseline list of community stakeholders and their common concerns were identified, together with suggested approaches to identify community stakeholders in each project. Community consultation is key to the process and engaging the community as widely and early as possible is recommended. Furthermore, key principles and an array of common methods for community stakeholder management in the planning stages of the project are presented, while acknowledging that not all stakeholders can be satisfied at each instance. Ultimately these findings were consolidated in a community consultation checklist that serves as a more systematic and practical tool in guiding project managers in their community stakeholder management initiatives during planning. The research findings herewith contribute valuable insights to the existing body of knowledge in this area and also provide enhanced practical guidance to project managers in achieving successful community stakeholder management during planning, facilitating higher acceptance for the proposal, carrying out a more efficient and effective planning process and improving the likelihood for project approval from both authoritative and judiciary standpoints.

When more induction generator based wind farms are integrated into the power system, the system voltage dips and stability problems may arise due to the draw of reactive power by induction generators. The power system short-circuit event induced wind turbine trips could result in power imbalance and lead to power system instability. This thesis studies the influence of two compensation techniques on the wind turbine low voltage ride-through (LVRT) capability. One of which is based on a parallel compensation by a static synchronous compensator (STATCOM), and the other one is a series compensation by a dynamic voltage restorer (DVR). In this study, Matlab tools and models are used to simulate an active-stall controlled fixed-speed induction generator connected to a power system. Two system configurations are used to simulate three phase faults and compare the improvement of wind turbine LVRT capability due to the two studied compensation techniques. Simulation results indicate that wind turbine compensated by DVR would have better LVRT performance than that by STATCOM in dealing with the low voltage situations due to system faults.