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Implicações das propriedades estruturais de redes para o gerenciamento de projetos interorganizacionais de geração de energia eólicaAdami, Vivian Sebben 29 May 2015 (has links)
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Previous issue date: 2015-05-29 / Nenhuma / Uma das prioridades da agenda sustentável mundial é a promoção do uso de fontes energéticas renováveis, como a energia eólica. O crescimento do uso dessa fonte desenvolveu uma indústria na Europa e nos Estados Unidos para atender à demanda desses mercados precursores. Na última década, o Brasil, juntamente com a China e a Índia, vem investindo na geração eólica, e destacando-se no cenário mundial. A implantação de parques eólicos acontece por meio de projetos interorganizacionais (PIOs), envolvendo atividades compartilhadas entre empresas com interesses e capacidades diferentes em um ambiente de riscos e incertezas. Esta pesquisa propõe-se a contribuir com a temática ainda nova dos PIOs da indústria eólica, tendo sustentação nos progressos recentes do conhecimento sobre redes e propriedades estruturais. O objetivo principal é compreender as implicações das propriedades estruturais das redes estabelecidas no contexto dos PIOs de geração de energia eólica para seu gerenciamento. Estudos recentes têm adotado a perspectiva de redes para a compreensão e o aprimoramento das relações nos PIOs. Nesses estudos, os PIOs são entendidos como uma rede de atores interdependentes que pode ser detalhada a partir de suas propriedades estruturais em vários níveis. O mapeamento da rede, sua análise e caracterização a partir de múltiplos níveis iluminam questões até então complexas para o desenvolvimento dos parques eólicos. A introdução do nível triádico permitiu novas visões aos aspectos estruturais e posicionais dos atores. As redes são um fenômeno relativamente recente, e o campo de estudos ainda se ressente com a falta de pesquisas que abordem as estruturas relacionais entre os atores. A utilização conjunta de abordagens quantitativas, com a adoção da Análise de Redes Sociais, e qualitativas, com a realização de entrevistas semiestruturadas, possibilitou incorporar diferentes (e complementares) perspectivas de análises ao fenômeno. Em termos acadêmicos, uma das contribuições da pesquisa foi o desenvolvimento de um conceitual teórico para as propriedades estruturais dos PIOs em vários níveis, reforçando o poder explicativo da estrutura frente ao dos atributos individuais dos atores. Outra contribuição foi a identificação de relações e papéis-chave para a estruturação de modelos de gestão mais efetivos. Relações informais, invisíveis nas redes de fornecimento e contratos, acontecem dentro de uma lógica cooperativa, e são importantes na coordenação do projeto. Em termos gerenciais, as contribuições centraram-se na compreensão da estrutura relacional dos PIOs, de seu funcionamento, e em aspectos relacionados às implicações das propriedades estruturais para seu gerenciamento. A composição e organização dos PIOs foi revelada assim como a importância da cooperação ou de uma estrutura relacional que estimule a cooperação entre os participantes do projeto. / One of the priorities of sustainable world agenda is promoting the use of renewable energy sources, like wind power. The growth of this source developed an industry in Europe and in the United States to supply the demand of these precursors markets. Recently (in the last decade), Brazil along with China and India has been investing in wind generation and emerging on the world scenario. The deployment of wind farms happens through inter-organizational projects (IOPs), involving shared activities among companies with different interests and capabilities in an environment of risks and uncertainties. This research aims to contribute to the still new topic of the wind industry IOPs, having support in recent progress of knowledge on networks and structural properties. Its main goal is to understand how the characteristics of networks established in the context of wind power generation IOPs affect the development of Brazilian initiatives. Recent studies have adopted social networking perspective for understanding and improving relations in IOPs. In these studies, IOPs are understood as a network of interdependent actors that can be detailed from their structural properties at various levels. Network mapping, analysis and characterization from multiple levels shed light to issues hitherto complex for the development of wind farms. The introduction of the triadic level, still little explored in studies of interorganizational networks, enables new visions to actors structural and positional aspects. The networks are a relatively new phenomenon, and the field of study still resents the lack of research that address the relational structures between the actors. The joint use of quantitative approaches, with the adoption of social network analysis, and qualitative, based on semi-structured interviews, made it possible to incorporate different (and complementary) analysis perspectives to the phenomenon. In academic terms, one of the research contributions was the development of a theoretical framework for the structural properties of IOPs on many levels, reinforcing the explanatory power of the structure over the individual attributes of the actors. Another result was the identification of relations and key roles for structuring more effective management models. Informal relations, invisible in supply and procurement networks, happen within a cooperative logic and are important in coordinating the project. In managerial terms, the contributions focused on understanding the relational structure of the IOPs, their operation, and issues related to the implications of the structural properties to its management. The composition and organization of IOPs was revealed as well as the importance of cooperation or of a relational structure that encourages cooperation between project participants.
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Ανάλυση προσδοκώμενης λειτουργίας και σύγκριση της με πραγματικές μετρήσεις σε αιολικό πάρκο 38MWΜελισσάρης, Ιωάννης 27 April 2015 (has links)
Το αντικείμενο της παρούσας διπλωματικής εργασίας είναι η ανάλυση και η επεξεργασία δεδομένων από αιολικό πάρκο εγκατεστημένης ισχύος 38 MW, η σύγκρισή τους με τις θεωρητικά αναμενόμενες τιμές και η εξαγωγή συμπερασμάτων σχετικά με τη λειτουργία του αιολικού πάρκου.
Για να επιτευχθεί ο στόχος της εργασίας αρχικά γίνεται μία γνωριμία με το σύνολο των ανανεώσιμων πηγών ενέργειας και τονίζεται η σημαντικότητά τους και ο σπουδαίος ρόλος που επιτελούν στη σημερινή ενεργειακή κρίση. Ύστερα η εργασία εστιάζει στην αιολική ενέργεια, σαν έναν από τους κύριους εκφραστές των ανανεώσιμων πηγών ενέργειας και παρουσιάζει τους λόγους και τους τρόπους αξιοποίησής της.
Ακολουθεί η αναλυτική περιγραφή των χαρακτηριστικών της ανεμογεννήτριας, η οποία είναι το βασικό εργαλείο για τη διαδικασία μετατροπής της αιολικής ενέργειας σε ηλεκτρική. Στη συνέχεια παρουσιάζεται η ανάλυση ενός συστήματος ανεμογεννητριών, γνωστό και ως αιολικό πάρκο, η ύπαρξη του οποίου οφείλεται στην ανάγκη μέγιστης απορρόφησης της αιολικής ενέργειας.
Αφού περιγραφούν όλες οι απαραίτητες έννοιες για την κατανόηση της λειτουργίας του αιολικού πάρκου, σειρά έχει η αναλυτική περιγραφή της διαδικασίας μελέτης, κατασκευής και διασύνδεσής του στο δίκτυο, χρησιμοποιώντας ως υπόδειγμα πραγματικές μελέτες και σχέδια από την κατασκευή ενός εγκατεστημένου αιολικού πάρκου.
Από το αιολικό πάρκο που χρησιμοποιήθηκε ως υπόδειγμα, συγκεντρώθηκαν διάφορα δεδομένα λειτουργίας, όπως η παραγόμενη ισχύς, η ταχύτητα και η διεύθυνση του ανέμου, κ.ά. Τα δεδομένα αυτά αναλύθηκαν και επεξεργάστηκαν και τα αποτελέσματα παρουσιάζονται στη συνέχεια. / The subject of this thesis is to analyze and process the data extracted from a wind farm, with installed capacity of 38 MW, then compare them to the theoretical estimated values and finally draw conclusions about the operation of the wind farm.
In order to reach the goal of the thesis, initially, all the renewable energy sources are introduced and their significance and the important role they play in today's energy crisis are highlighted. Then the paper focuses on wind power, being one of the most frequently exploited renewable energy source and presents both the advantages and disadvantages and the ways of exploitation.
Following the aforementioned is a detailed description of the characteristics of the wind turbine, which is the main equipment for the conversion of wind energy into electricity. The necessity of power nowadays has forced us to find ways for best absorption of wind energy. A wind farm allows us to get the maximum out of the wind potential of an area therefore what follows is the analysis of the main components of a wind farm.
After describing all the necessary concepts for understanding the operation of the wind farm, a detailed description of the design process, construction and interconnection with the grid is presented. The description is made by using studies and drawings of an actual construction project of an installed wind farm.
From the wind farm that was used as a template, were gathered various operating data such as power output, air speed and direction, etc. These data have been analyzed and processed, and the results are projected in the last two chapters of this thesis.
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Triukšmo sklaidos vėjo jėgainių parke tyrimas ir vertinimas / Investigation and Assessment of noise dispersion of a wind farmEivienė, Rasa 17 June 2013 (has links)
Baigiamajame magistro darbe nagrinėjamas dviejų vėjo jėgainių parkų keliamas triukšmas. Analizuojami triukšmo susidarymo ypatumai vėjo jėgainių parkų viduje bei sklaida parko išorėje. Vertinamos infragarso bei žemo dažnio garso dažninės charakteristikos vėjo jėgainių parkų aplinkoje. Darbą sudaro 4 skyriai. Pirmajame skyriuje apžvelgiama garso fizikinė prasmė, triukšmo šaltiniai, problema bei keliamo triukšmo poveikis žmonėms. Antrajame skyriuje aprašomi tyrimo objektai bei eksperimentinė vėjo jėgainių keliamo triukšmo tyrimų metodika. Trečiajame skyriuje pateikiami dviejų vėjo jėgainių parkų keliamo triukšmo tyrimų rezultatai bei analizė. Dviejų vėjo jėgainių parko Anužių kaime bei šešių vėjo jėgainių parko „Liepynė“ Kretingos rajone. Ketvirtajame skyriuje pateikiamas vėjo jėgainių parkų keliamo triukšmo modeliavimo rezultatai taikant „CadnaA“ modeliavimo programą. Taip pat pateikiamos bendros išvados, rekomendacijos, literatūros sąrašas ir publikacijų sąrašas šio darbo tema. Darbo apimtis – 103 p. teksto be priedų, 72 iliustr., 5 lent., 84 bibliografiniai šaltiniai. / In this master analyzing of noise dispersion around two wind farms. Analyzing the noise generation and dissemination characteristics of wind farms within and outside the park. Assessed infrasound and low frequency sound frequency response in the places around of wind farms. The master consists of 4 chapters. The first chapter provides an overview of sound physical meaning, sources of noise, the problem and the noise impact to people. The second section describes the objects of research, experimental wind noise research methodology. The third section presents the research results and analysis of two wind parks. Wind farm of two wind turbines in Anužiai village and wind farm of six wind turbines in „Liepynė“ Kretingos district. The fourth section describes the modeling results of wind park using simulation program „CadnaA“ . Also provides an overall conclusion, recommendations, bibliography and list of publications of this master. The volume of master – 103 pages text without attachments, 72 pictures, 5 tables, 84 references.
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Δυναμικές επιδράσεις του αιολικού συστήματος στο σύστημα ηλεκτρικής ενέργειας / Dynamic influences of the wind system to power systemΣταματόπουλος, Ευάγγελος, Σαμαράς, Ιωάννης 29 August 2011 (has links)
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.
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Avaliação de ruídos em aerogeradores situados no complexo eólico Serra Azul - BaGomes, Leonardo Rafael Teixeira Cotrim 11 May 2017 (has links)
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Previous issue date: 2017-05-11 / Agência 1 / O estado da Bahia detém um dos maiores potenciais eólicos do Brasil, dispondo de uma infinidade de complexos e parques eólicos instalados em seu território. O ritmo acelerado de fabricação, implantação e operação dos aerogeradores foi preponderante para assegurar maior participação no cenário nacional de produção de energia elétrica, aumentando a segurança e fortalecendo o setor energético, promovendo o crescimento econômico e social do país. Embora seja uma fonte de energia tida como alternativa e sustentável, se comparada às tradicionais, a geração de energia elétrica advinda da força dos ventos é capaz de gerar impactos ambientais indesejáveis, que podem ser verificados desde a cadeia de produção dos aerogeradores até os ecossistemas nas vizinhanças dos parques e complexos eólicos. Os impactos ambientais são diversos, entretanto quando se restringe às populações que vivem próximos aos parques alguns impactos se tornam mais evidentes, tais como: o impacto visual, ruído, interferências eletromagnéticas, corona visual, efeito estroboscópio. O presente estudo visa avaliar os ruídos emitidos por aerogeradores no Complexo Serra Azul-BA, a partir de coletas de dados realizadas no local com distâncias pré-definidas entre o aerogerador e o receptor, utilizando um método de estimativa de ruído da Agencia Internacional de Energia (IEA), cujo resultado foi comparando com os dados fornecidos pelo fabricante dos aerogeradores e as principais normas vigentes no mundo quanto aos limites permissíveis de ruído. Os resultados das medições demonstraram que através do método de medição do ruído na fonte proposto pela IEA é possível determinar de forma satisfatória o nível de pressão sonora emitido pelos aerogeradores e, portanto, auxiliar no monitoramento ambiental. Através dos resultados obtidos notou-se também, que havia diferença na emissão de ruído entre aerogeradores no parque, sugerindo que um deles pudesse estar desregulado, emitindo ruído próximo do limite superior especificado pelo fabricante, em velocidades de vento abaixo do valor da potência nominal do aerogerador. A pesquisa avaliou normas e leis aplicadas no âmbito nacional e internacional acerca de emissão e monitoramento de ruídos gerados por aerogeradores. Foi visto que há grande variedade de conceitos e que geralmente cada país ou região possui normas próprias a serem utilizadas para o controle, monitoramento, medição e aplicação de leis. A partir do estudo de legislações existente no mundo, foi possível propor ações mitigadoras, atualização e criação de novas normas para o Brasil, haja visto que o país é carente de normas específicas que abranjam de forma adequada a questão dos ruídos emitidos pelos aerogeradores. / The state of Bahia holds one of the largest wind potential in Brazil, with a multitude of wind farms installed in its territory. The quickly increase of manufacturing, implementation and operation of wind turbines was important to ensure greater participation in the national scenario of electric power generation, increasing safety and strengthening of the energy sector, promoting economic and social growth of the country. The wind power it is an alternative and sustainable source of energy, compared to traditional ones, although the production of electric energy from the force of the winds can generate undesirable environmental impacts that can happen from the production chain of the wind turbines to the ecosystems around the windfarms. Environmental impacts are diverse, however when it is restricted to the populations that living near the windfarms, some issues become more evident, such as visual impact, noise, electromagnetic interference, visual corona, strobe effect. The present study aims to evaluate the wind turbine noises in the Serra Azul-BA windfarm, from data collections performed at the site with pre-defined distances between the wind turbine and the receiver using an International Energy Agency (IEA) noise estimation method. With the collected data is possible to compare the noise with the values provided by manufacturer of the wind turbines and the main standards in the world. The results of the measurements shows that through the method of measurement of noise at source proposed by the IEA it is possible to determine satisfactorily the sound pressure level emitted by wind turbines and therefore to assist in the environmental monitoring. Can be verified differences in the noise emission between wind turbines in the park, suggesting that one of them could be deregulated, emitting noise near the upper limit specified by the manufacturer, at wind speeds below the nominal power Wind turbine. The research evaluated national and international laws and regulations on the emission and noise environmental monitoring generated by wind turbines. Nowadays the world have a great variety of concepts and each country or region have its own norms to be used to control, monitoring, measure and enforcement of laws. With the study of existing laws in the world, it was possible to propose mitigating actions, updates and creation of new standards for Brazil, since the country lacks specific norms that adequately cover the issue of noises emitted by wind turbines.
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Understanding the interaction of wind farms and turbulent atmospheric boundary layer in a large eddy simulation framework: from periodic to LIDAR based data driven casesJanuary 2018 (has links)
abstract: This thesis focuses on an improved understanding of the dynamics at different length scales of wind farms in an atmospheric boundary layer (ABL) using a series of visualization studies and Fourier, wavelet based spectral analysis using high fidelity large eddy simulation (LES). For this purpose, a robust LES based neutral ABL model at very high Reynolds number has been developed using a high order spectral element method which has been validated against the previous literature. This ABL methodology has been used as a building block to drive large wind turbine arrays or wind farms residing inside the boundary layer as documented in the subsequent work. Studies conducted in the thesis involving massive periodic wind farms with neutral ABL have indicated towards the presence of large scale coherent structures that contribute to the power generated by the wind turbines via downdraft mechanisms which are also responsible for the modulation of near wall dynamics. This key idea about the modulation of large scales have seen a lot of promise in the application of flow past vertically staggered wind farms with turbines at different scales. Eventually, studies involving wind farms have been progressively evolved in a framework of inflow-outflow where the turbulent inflow is being fed from the precursor ABL using a spectral interpolation technique. This methodology has been used to enhance the understanding related to the multiscale physics of wind farm ABL interaction, where phenomenon like the growth of the inner layer, and wake impingement effects in the subsequent rows of wind turbines are important owing to the streamwise heterogeneity of the flow. Finally, the presence of realistic geophysical effects in the turbulent inflow have been investigated that influence the flow past the wind turbine arrays. Some of the geophysical effects that have been considered include the presence of the Coriolis forces as well as the temporal variation of mean wind magnitude and direction that might occur due to mesoscale dynamics. This study has been compared against field experimental results which provides an important step towards understanding the capability of the mean data driven LES methodology in predicting realistic flow structures. / Dissertation/Thesis / Turbulent flow past a large periodic wind farm / Doctoral Dissertation Mechanical Engineering 2018
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Requisitos de suporte de potência reativa para operação de usinas eólicasBento, José Antônio Chiabai 27 February 2013 (has links)
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Previous issue date: 2013-02-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A penetração de parques eólicos nos sistemas elétricos de potência tem apresentado
um grande crescimento no Brasil e no mundo devido à disponibilidade da matéria prima, os
ventos, e à necessidade de reformulação das matrizes energéticas a fim de reduzir os impactos
ambientais decorrentes da geração de energia elétrica. Porém, as usinas eólicas apresentam
variações nos despachos de potência devido à variabilidade de velocidade dos ventos. Estas
variações causam impactos no sistema, podendo afetar a confiabilidade e a estabilidade de
tensão. Além disto, a operação de determinados tipos de aerogeradores requer suporte
adicional de potência reativa.
Uma opção para aumentar as margens operativas e acomodar as intermitências de
regime dos ventos em sistemas elétricos de potência consiste na utilização de compensadores
estáticos de reativos (CER) junto às usinas eólicas. Estes equipamentos FACTS (Flexible AC
Transmission Systems) provêm suporte de potência reativa variável e de rápido controle, de
acordo com os requisitos operacionais dos aerogeradores.
Neste sentido, o presente trabalho apresenta uma metodologia para ajuste ótimo dos
parâmetros do CER visando dar suporte de potência reativa para a operação de usinas eólicas
em sistemas elétricos de potência. Para representar as intermitências no despacho de potência
dos aerogeradores, a metodologia proposta considera diferentes cenários de vento. O
problema é modelado através de fluxo de potência ótimo (FPO), associado à técnica de
decomposição matemática de Benders. Os parâmetros de ajuste do CER são a tensão de
referência e o coeficiente de inclinação da curva característica deste equipamento em regime
permanente. Destaca-se que o ajuste ótimo deste coeficiente é inédito na literatura
especializada. Testes com sistemas do IEEE são realizados para validar a metodologia
proposta. / The penetration of wind farms in power systems has shown tremendous growth in
Brazil and in the world due to the availability of the raw material, the wind, and the need to
redefine the energy mix to reduce the environmental impacts from the electrical energy
generation. However, the wind farms have variable outputs due to the variation of wind
speeds. These outputs impact the power system and can affect the reliability and the voltage
stability. Besides, the operation of some aerogenerators requires additional support of reactive
power.
An option for handling this feature and increasing the operative margins of power
systems is the use of static VAr compensators (SVC) together with the wind farms. These
FACTS devices (Flexible AC Transmission Systems) provide a variable reactive power
support, with a fast control according to the operational requirements of the aerogenerators.
In this sense, this work presents a methodology for the optimal adjustment of the SVC
parameters to give reactive power support for wind farms operating in power systems. The
proposed methodology considers different wind scenarios to represent the variations of the
wind farms outputs. The problem is modeled through an optimal power flow (OPF) and the
Benders decomposition technique. The SVC parameters for adjustment are its reference
voltage and the coefficient of its characteristic curve in stable state. It can be highlighted that
the adjustment of this coefficient is innovative for the literature. Tests with systems of the
IEEE are performed to validate the proposed methodology.
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Maintenance scheduling in the electricity industry : a particular focus on a problem rising in the onshore wind industry / Planification de la maintenance d’équipements de production d’électricité : une attention particulière portée sur un problème de l’industrie éolienne terrestreFroger, Aurélien 14 December 2016 (has links)
L’optimisation de la planification de la maintenance des équipements de production d’électricité est une question importante pour éviter des temps d’arrêt inutiles et des coûts opérationnels excessifs. Dans cette thèse, nous présentons une classification multidimensionnelle des études de Recherche Opérationnelle portant sur ce sujet. Le secteur des énergies renouvelables étant en pleine expansion, nous présentons et discutons ensuite d’un problème de maintenance de parcs éoliens terrestres. Le problème est traité sur un horizon à court terme et l’objectif est de construire un planning de maintenance qui maximise le revenu lié à production d’électricité des éoliennes tout en prenant en compte des prévisions de vent et en gérant l’affectation de techniciens. Nous présentons plusieurs modélisations du problème basées sur la programmation linéaire. Nous décrivons aussi une recherche à grands voisinages basée sur la programmation par contraintes.Cette méthode heuristique donne des résultats probants.Nous résolvons ensuite le problème avec une approche exacte basée sur une décomposition du problème. Dans cette méthode, nous construisons successivement des plannings de maintenance optimisés et rejetons, à l’aide de coupes spécifiques, ceux pour lesquels la disponibilité des techniciens est insuffisante. Les résultats suggèrent que cette méthode est la mieux adaptée pour ce problème. Enfin, pour prendre en compte l’incertitude inhérente à la prévision de vitesses de vent, nous proposons une approche robuste dans laquelle nous prenons des décisions garantissant la réalisabilité du planning de maintenance et le meilleur revenu pour les pires scénarios de vent. / Efficiently scheduling maintenance operations of generating units is key to prevent unnecessary downtime and excessive operational costs. In this work, we first present a multidimensional classification of the body of work dealing with the optimization of the maintenance scheduling in the operations research literature. Motivated by the recent emergence of the renewable energy sector as an Environmental priority to produce low-carbon power electricity, we introduce and discuss a challenging Maintenance scheduling problem rising in the onshore wind industry. Addressing the problem on a short-term horizon, the objective is to find a maintenance plan that maximizes the revenue generated by the electricity production of the turbines while taking into account wind predictions, multiple task execution modes, and technician-to-task assignment constraints. We start by presenting several integer linear Programming formulations of the problem. We then describe a constraint programming-based large neighborhood search which proves to be an efficient heuristic solution method. We then design an exact branch-and-check approach based on a decomposition of the problem. In this method, we successively build maintenance plans while discarding – using problem-specific cuts – those that cannot be performed by the technicians. The results suggest that this method is the best suited to the problem. To tackle the Inherent uncertainty on the wind speed, we also propose a robust approach in which we aim to take risk-averse decisions regarding the revenue associated with the maintenance plan and its feasibility.
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Analysis of Near-Surface Relative Humidity in a Wind Turbine Array Boundary Layer Using an Instrumented Unmanned Aerial System and Large-Eddy SimulationAdkins, Kevin Allan 11 August 2017 (has links)
Previous simulations have shown that wind farms have an impact on the near-surface atmospheric boundary layer (ABL) as turbulent wakes generated by the turbines enhance vertical mixing of momentum, heat and moisture. These changes alter downstream atmospheric properties. With the exception of a few observational data sets that focus on the impact to near-surface temperature within wind farms, little to no observational evidence exists with respect to vertical mixing. These few experimental studies also lack high spatial resolution due to their use of a limited number of meteorological sensors or remote sensing techniques. This study utilizes an instrumented small unmanned aerial system (sUAS) to gather high resolution in-situ field measurements from two state-of-the-art Midwest wind farms in order to differentially map downstream changes to relative humidity. These measurements are complemented by numerical experiments conducted using large eddy simulation (LES). Observations and numerical predictions are in good general agreement around a single wind turbine and show that downstream relative humidity is altered in the vertical, lateral, and downstream directions. A suite of LES is then performed to determine the effect of a turbine array on the relative humidity distribution in compounding wakes. In stable and neutral conditions, and in the presence of a positive relative humidity lapse rate, it is found that the humidity decreases below the turbine hub height and increases above the hub height. As the array is transitioned, the magnitude of change increases, differentially grows on the left-hand and right-hand side of the wake, and move slightly upward with downstream distance. In unstable conditions, the magnitude of near-surface decrease in relative humidity is a full order of magnitude smaller than that observed in a stable atmospheric regime.
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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) / Compensation for social and ecological impacts of development project : acceptance, perceptions and preferences of local stakeholders. Application of the projected offshore wind farm of the Bay of Saint-BrieucKermagoret, Charlène 17 December 2014 (has links)
Les politiques de développement durable ont fait émerger de nombreux outils qui visent à concilier les enjeux de développement économique et ceux de préservation des intérêts sociaux et environnementaux. Parmi eux, la compensation territoriale se matérialise par l’attribution, à un territoire subissant les impacts négatifs d’un aménagement déclaré d’utilité publique, d’un ensemble de mesures visant à maintenir à niveau acceptable le bien-être des individus et l’état écologique du milieu. Elle permet ainsi de rétablir un équilibre entre la dimension globale du projet, qui ne considère que ses effets positifs, et la dimension locale, dans laquelle les externalités positives et négatives du projet rentrent en jeu. Initié par un questionnement sur la mise en oeuvre d’un tel outil de politique publique au sein de territoires spécifiques, l’objectif principal de ce travail est de caractériser la demande de compensation par les acteurs du territoire au regard des impacts perçus dans un contexte de projet d’aménagement. Ce travail explore les perceptions des acteurs du territoire de la baie de Saint-Brieuc directement concernés par un projet de parc éolien en mer vis-à-vis de ce principe de compensation. Pour ce faire, des approches qualitatives et quantitatives ont été utilisées de manière complémentaire et font appel à des outils spécifiques tels que la cartographie cognitive floue et la méthode des choix expérimentaux. Cette démarche nous a permis de produire de nombreux éléments de compréhension quant à la manière dont ces acteurs perçoivent les impacts d’un tel projet d’aménagement, acceptent ou non le principe de compensation comme outil de réponse aux impacts négatifs du projet et envisagent la mise en oeuvre de la compensation à travers leurs préférences vis-à-vis de différentes types d’actions – indemnisations financières, investissements dans des biens communs, restauration écologique. Les résultats de ce travail montrent que les perceptions, très hétérogènes au sein des acteurs du territoire, s’expliquent en grande partie à travers le concept de Communautés de Pratiques. Finalement, lorsque le principe de compensation est accepté par les acteurs du territoire, la logique d’équivalence qui conditionne la demande de compensation peut s’expliquer de trois manières différentes : une équivalence territoriale dans laquelle les bénéfices issus de la compensation doivent profiter à l’ensemble de la population du territoire impacté ; une équivalence écologique dans laquelle le niveau de fonctions écologiques et de services écosystémiques est maintenu constant, une équivalence basée sur des valeurs économiques pour pallier le manque à gagner de certaines activités professionnelles. / In 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.
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