L’optimisation de la maintenance industrielle revêt différents aspects suivant les objectifs fixés par l’exploitant industriel. L’objectif le plus courant est la réduction des arrêts et des pannes. Le but est d’assurer une disponibilité élevée de l’équipement. Nous allons plus loin en nous posant la question de l’efficience des coûts de maintenance et de la rentabilité. La réponse donnée ici à cette question provient des résultats d’une fonction de coût associée à une plateforme de simulation basée sur les systèmes multiagents. Le choix du paradigme Agent est motivé par l’utilisation des SMA à d’autres fins de simulation et qu’ils garantissent une forme de souplesse quant à l’évolution du contexte métier. La thèse porte sur un modèle de systèmes multiagents destiné à améliorer la gestion des parcs éoliens à travers la définition d'un ensemble de critères financiers propres à l’exploitant éolien. / Optimization & maintenance in the Industrial sector covers different aspects according to the objectives set by the industrial operator. Their common goal is to reduce downtime and failures. For the windfarm operators the goal is to ensure the wind farms high availibility. We went one step further by asking the question of the efficiency of maintenance costs and the profitability. The answer to this question comes from the results of a cost function associated to a simulation model based on multiagents systems. The choice of the multiagent paradigm is motivated by the use of MAS for other simulation purposes and the fact that they guarantee a kind of flexibility regarding the evolution in a moving business context. This Phd thesis focuses on a multi-agent systems model designed to improve the management of wind farms through the definition of a set of financial criteria specific to the wind farm operators.

Pour parvenir à une maîtrise des enjeux en matière de changement climatique les stratégies politiques se succèdent à tous les échelons du territoire. Au sein de ces politiques, les projets de développement d'énergies renouvelables ont retenu mon attention en particulier les projets de parcs éoliens. Fortement développés au cours du XXIème siècle, ces projets mis en place pour répondre aux attentes en matière de lutte contre le réchauffement climatique s'articulent-ils pour autant au développement durable des territoires ? L'ambition de ce travail est de chercher à comprendre les dynamiques de la durabilité. Pour cela, je partirai d'un postulat de recherche selon lequel une approche du développement durable par le territoire permet de renouveler l'étude de la durabilité en aménagement. Dans la première partie, j'ancre donc territorialement les études menées sur les politiques de durabilité en mobilisant la notion de développement territoriale durable. Dans la deuxième partie, je m'intéresse aux projets de parcs éoliens en tant que projets de territoire, ce qui me permet de questionner les politiques durables sur des micro-espaces en milieu rural. Il s'est avéré que ces espaces répondent aux mêmes logiques d'aménagement que celles du milieu urbain. Cette constatation m'a amenée à formuler l'hypothèse d'une « nouvelle forme d'organisation des territoires » sans distinction entre l'urbain et le rural. La troisième partie s'attache plus particulièrement à étudier le rôle de catalyseur d'action des acteurs dans le processus de durabilité. Par leurs implications territoriales conscientes ou non, ils suscitent des réactions territoriales. Ces réactions sont la manifestation d'un nouvel intérêt pour le territoire et d'un nouvel ancrage territorial, nécessaire à la conduite de projets territoriaux durables. / Political strategies have been renewed regularly to better respond to climate issues, across international, national, regional and local levels. Within those politics, renewable energy projects caught my attention. Developed in the XIXth century, this project was implanted to uncross the climate change. Therefore, the research aims at understanding how wind power plants interfere "positively or negatively" with place-based territorial constructions. The point is to address the trade-offs between spatial equity and intergenerational equity, which are the core of sustainable policies. I choose a territorial approach of sustainable development to better respond to the core aim. I think this approach contributes to renew the sustainable studies in urban planning. Consequently, in my first part, I settle the sustainable studies in territorial context by mobilizing sustainable territorial development concept. In the second part, my interests focus on wind farms projects; reconsidering such projects is to get some perspectives towards the territorial projects and sustainable policy particularly in micro-territory in rural area. The finding was a concept of “negotiated territory” without distinction between planning in rural or urban area. The third part, tried to understand the stakeholders implementation in sustainable decision-making process. With our territorial positions (conscious or not) they're because of territorial effects. These reactions are reflecting a new interest to the territory, a new links to the local communities, necessary to conduce territorial sustainable development projects.

This thesis validates SIMLOX as a simulation tool for wind energy operation and maintenance (O&M). SIMLOX have been used for modeling O&M in other sectors since 2002 but have recently begun to be used for simulating wind energy. This study validates SIMLOX for the newly introduced sector by creating a model of an existing offshore wind farm. The model used real historical data as input and the output was compared to real system response quantities (SRQs). Example of SRQs which were compared was time based availability, energy based availability, energy production, weather days, and item replacements. The study showed that SIMLOX is very well suited for this type of studies. It also showed that the major difficulty lies in obtaining proper input data. All models simulated the exact right number of major item replacements. The time based availability was considered to be the most important SRQ. The time based availability turned out to be between 0.11 - 0.66 percentage points too high compared to reference data. This most certainly depended on an overestimated work schedule for the technicians. Validation is the process of determining the degree to which a model is an accurate representation of the real world from the perspective of the intended uses of the model. This report presents all necessary knowledge to validate SIMLOX as a tool for wind energy simulations but it is thus up to the user to decide whether or not the output is accurate enough for their intended use.

Year 2040 the goal is to have a 100 % renewable Swedish energy system. Svenska kraftnät (Svk) predicts fully decommissioned nuclear power plants and an increased amount of connected wind power plants, especially offshore, year 2045. These kind of renewable power plants are non-synchronous and do not provide the grid with the same system stability services naturally as synchronous generators, such as nuclear power plants. With the increased number of renewables connected, one future challenge is to maintain the stability of the power grid. Grid stability can be divided into voltage-, frequency- and rotor angle stability.This thesis has investigated how large-scale offshore wind power plants (OWPPs) can contribute with reactive power compensation and in turn voltage stability to a nearby onshore power grid in Sweden. The evaluation has been done from the perspective of the TSO and the OWPP owner interests, with a focus on grid codes, economic incentives and technical capabilities.This project has been made in three parts. First, a comparison of voltage stability control requirements in different European grid codes was made. Secondly, static power flow simulations of a case study of a 1000 MW OWPP have been performed in PowerWorld Simulator, testing the OWPP’s reactive power outputs under different circumstances. Thirdly, a market opportunity analysis has been completed, analyzing reactive power market opportunities for OWPPs as well as for TSOs.The study shows that the reactive power capabilities of the simulated OWPP is considerable higher than the Swedish grid codes requires. Thus, an opportunity is to make the grid codes stricter, in combination with economic incentives. The case study showed that the distance offshore has an impact of the reactive power reaching the grid onshore. Though, the OWPP’s contribution to local voltage stability onshore is considered as good. Finally, with short- and long-term contracts, a reactive power market can be favorable for both the OWPP owner and the TSO.

The interaction between wind turbines in simple wind farm layouts is investigated with the purpose of observing the influence of wake loss phenomenon on the energy production of downwind turbines. Following an intensive exploration stage about wind farm aerodynamics and wake modeling subjects, several tests cases are designed to represent various wind farm configurations, consisting of different number of wind turbines. These cases are simulated by using DNV GL WindFarmer software which provides the opportunity of performing simulations with two different wake modeling techniques, namely Modified PARK and Eddy Viscosity. Various terrain and ambient turbulence intensity conditions are considered during the test cases. Also three different turbine types having different hub heights, rotor diameters and power-thrust coefficients are used in order to observe the effect of turbine characteristics on wake formation. Besides WindFarmer, WAsP and MATLAB tools are used in some simulation stages in order to generate input data such as wind and terrain conditions or farm layout configurations; and to process the data obtained in the end of these test cases. Simulations which are executed in the presence of a predominant wind direction from a narrow direction bin indicate that, even though there exists no significant interaction between the turbines placed in abreast configurations, successive turbine rows affect each other strongly due to the existence of the wake region of upwind turbines. It is observed that downwind spacing between turbine rows required to recover wake deficit up to a certain level changes depending on terrain and ambient turbulence intensity conditions together with turbine characteristics. For instance increasing surface roughness length (or ambient turbulence intensity) of a given site by keeping all the other parameters constant can provide up to 20% (or 30%) decrease in the required downstream distance to reduce wake loss to 5% level in a simple tandem layout consisting of two wind turbines. Further test cases are executed with various numbers of wind turbines in different configurations to observe the effect of partial, full and multiple wake regions on total farm efficiency. The results obtained from these cases are used in order to have a comparison between several farm layouts and evaluate their advantages and drawbacks.

Wind is a fast growing energy resource and the demand for clean energy is increasing with growing interests from media, governmental institutions and the public (EWEA, 2004). The increased interest towards the wind energy market has led to a more competitive environment where it is crucial for a project developer to select projects most likely to succeed, in terms of profitability, among alternatives on the market. To enable such selection, an evaluation process is often applied. Furthermore, traditional evaluation processes are often performed at completion of a project where an early indication of a project’s potential profitability is often missing (Samset & Christensen, 2015). At the early phase of a wind energy project the multiple factors influencing the project’s outcome are often conflicting and contain high level of uncertainty and the evaluation process becomes complex (Kumar et al., 2017). In addition, these factors are difficult to quantify and to determine their relative weight of importance (Çolak & Kaya, 2017). This thesis aims to problematise the early project phase by contributing with a practical tool for evaluating wind energy projects at this phase. In addition, the thesis aims to contribute with an identification and monetarily quantification of the important factors to assess when doing so. The thesis is conducted as a case study at a company developing wind energy projects in Sweden. Due to the multiple factors that influencing a project’s outcome, MCDM (multi-criteria decisionmaking) analysis is used as the research process to create the tool. Findings from this study show that key factors that are possible to quantify at an early phase are conditions for civil works, grid conditions, wind resource and electricity price area. In general, their relative importance, measured in relative increase of IRR, is wind resource, electricity price area, grid conditions and civil works in the descending order. This study has four contributions, three theoretical and one practical. Firstly, the study confirms MCDM as a suitable analysis to use, when creating an evaluation model for wind energy projects. Secondly, the study confirms most of the important factors mentioned in the literature to assess when evaluating a wind energy project. However, this study contributes with insights that only conditions for civil works, grid conditions, wind resource and electricity price area can be quantified for the purpose of creating an evaluation tool at an early phase. Thirdly, previous studies have focused less on determining the relative weight of importance of the relevant key factors and this study contributes by quantifying and determining which of these key factors that are of relevance in an evaluation. Lastly, this study contributes practically by creating an evaluation tool suggested to be used by the case company to compare different projects on the market and form investment decisions based on financial data. Furthermore, the tool facilitates an equal evaluation process for all projects, thus leading to a more standardised decision-making process where the case company can focus their resources on the projects most likely to succeed. / Vind är en snabbväxande energiresurs där efterfrågan efter grön energi ökar från media, statliga myndigheter och allmänheten. Det ständigt ökande intresset av vindenergi har lett till en allt mer konkurrenskraftig marknad där det är viktigt för en projektutvecklare att välja de projekt som är mest troliga att bli lönsamma bland de tillgängliga projekten på marknaden. Dessa urval sker oftast genom en projektutvärderingsprocess. Dock sker merparten av de traditionella projektutvärderingarna i slutet av ett projekt där en tidig indikation rörande ett projektet lönsamhet oftast saknas (Samset & Christensen, 2015). Anledningen till detta är att vindkraftsprojekt består av flera motsägande faktorer med en hög osäkerhet som påverkar ett projekts resultat, vilket leder till en komplex utvärderingsprocess i ett tidigt skede (Kumar et al., 2017). Dessutom är dessa faktorer svåra att kvantifiera vilket gör det svårt att vidare bestämma deras relation i förhållande till varandra (Çolak & Kaya, 2017). Detta examensarbete ämnar därför till att problematisera den komplexa utvärderingsprocessen i ett tidigt skedde genom att skapa ett praktiskt verktyg för en simplifierad utvärderingsprocess av vindkraftsprojekt. Detta examensarbete är utformat som en fallstudie på ett företag i Sverige som utvecklar vindkraftsprojekt. På grund av antalet faktorer som påverkar projektens lönsamhet används MCDM-analys som forskningsprocess för att skapa verktyget. Resultat från denna studie visar att de nyckelfaktorer som är möjliga att kvantifiera i det tidiga skede är: infrastruktur, nätanslutning, vindresurs och elprisområde. Resultaten visar även att faktorernas påverkan, mätt i relativ ökning av IRR, är i fallande ordning: vindresurs, elprisområde, nätanslutning och infrastruktur och att dessa, i fallande ordning, är relevanta att utvärdera. Denna studie har totalt fyra bidrag, varav tre teoretiska och ett praktiskt bidrag. Det första bidraget är en konfirmation av att MCDM är en lämplig analysmetod vid skapandet av utvärderingsverktyget. Det andra bidraget är en konfirmation av de faktorer som nämns i litteraturen som viktiga vid en utvärderingsprocess i ett tidigt skede. Dock är endast faktorerna infrastruktur, nätanslutning, vindresurs och elprisområde möjliga att kvantifiera i detta skede. Det tredje bidraget är kunskap gällande faktorernas förhållande till varandra och vilka som är relevanta att utvärdera. Det praktiska bidraget är utvärderingsverktyget där företaget rekommenderas att använda det för att jämföra olika projekt på marknaden och fatta välinformerade beslut baserat på finansiell data. Dessutom bidrar verktyget med en likvärdig utvärderingsprocess för alla projekt vilket leder till en mer standardiserad beslutsprocess där företaget kan fokusera sina resurser på de projekt som är mest troliga att bli lönsamma.

Wind is the second largest renewable energy source after solar. It is one of the fastest growing sources of electricity in the world and currently of wind energy is installed in the United States and an additional is under construction (Office of Energy and Environment Affairs, 2011). For the growth of wind electricity, one of the most prominent environmental concerns relates to the death of birds, bats and other avian species resulting from collision with turbine blades. This thesis develops a model that provides the optimal strategy of turning the turbines off in a wind farm for certain periods to mitigate bird mortalities. We first create a single turbine optimization model for each hour on each day of a single month. We maximize the expected revenue generation and limit the expected bird mortalities to a certain level to solve for the dates and times for which the turbine should be turned off. The optimization problem is found to be part of common class of problems called Knapsack problems and through experiments we conclude that a linear programming (LP) relaxation of the problem provides a near-optimal solution. We extend the single-turbine model to a multiple-turbine model applicable to a wind farm. In this case, we solve for the percentage of wind turbines that should be turned off to limit the expected bird mortalities to a certain level. Finally, we carry out an uncertainty analysis and estimate probability distributions over the outcome of optimal strategy of turning the turbine off. We consider the Cape Wind project as a case study and limit the analysis to only one species of endangered birds called the common loon. We find that in order to save an expected number of 10 such birds in the month of March; we need to turn the turbine off for a total of 23 hours spread over specific dates and times. The average cost per bird was found to be $171.

Cost efficient operation and maintenance strategies are crucial for reducing cost of wind energy. Since the regime change from feed-in tariffs to an auction-based bidding system for capacity in most European wind projects, levelized cost of energy is challenged constantly. Therefore, new technologies such as new controllers are developed to improve operation and to increase profit. Previous research studies demonstrated the advantage of increased power output of wake redirection control. However, understanding and quantifying the impact of wind farm control technologies on operation and maintenance strategies is inevitable to evaluate the economic feasibility of such new technologies. Thus, an event-based O&M simulation tool has been developed. Besides general modules, such as the wind turbine model, the weather forecasting model and a model for simulating corrective and planned maintenance, the developed tool also takes wake effects into account. This allows considering different power productions for each individual turbine and a failure rate distribution within the wind farm which is based on altering loads on the different components. Both aspects are driven by changes in operation when applying a new controller technology. Exemplarily, the economic feasibility of a closed-loop active wake steering control has been analysed. Main achievements of this study are the possibility to quantify the impact of the active wake steering control on O&M related KPIs. Results show that additional loads caused by applying yaw-misalignment and redirecting wake, lead to an increase in OPEX. However, the achieved energy production gain and thus related additional revenue exceeds additional cost in the case study. Nonetheless, the study reveals that the profitability of the controller is highly dependent on the electricity price which can be acquired during the wind farm’s lifetime.

Durch die Zunahme von Offshorewindparks wird der anthropogene Lärmpegel im Meer weiter ansteigen. Deshalb ist es notwendig, mögliche negative Effekte von Windturbinenschall auf Fische zu erkennen und zu minimieren. Um mögliche Effekte des Turbinenschalls auf Kabeljau (Gadus morhua) und Scholle (Pleuronectes platessa) zu untersuchen, wurden die Fische in Laborversuchen verschiedenen tiefen Frequenzen und Schallstärken, wie sie von Windturbinen emittiert werden ausgesetzt. Ein ringförmiges Betonversuchsbecken mit 10 Metern Durchmesser wurde mit Schallisolationwänden in verbundene Viertel unterteilt, wodurch im Becken eine Schalldruckdifferenz von 32-52 dB, abhängig von Frequenz und produziertem Schalldruckpegel erzeugt wurde. Die Fische, die sich frei im Becken bewegen und so, wenn sie wollten, den höchsten Schalldruckpegeln ausweichen konnten, wurden monofrequenten Tönen im Frequenzbereich zwischen 25 und 250 Hz in Schalldruckpegeln von 130 und 140 dB re 1 µPa ausgesetzt. Die Position der Fische im Becken wurde in den 24-Stunden-Phasen vor, während und nach Beschallung verglichen und zeigte in den meisten Versuchen während Beschallung signifikant weniger Kabeljau in der Nähe der Schallquelle, als in den Phasen vor und nach Beschallung. Scholle zeigte uneinheitliche Reaktionen, die teilweise auf Meideverhalten, in anderen Versuchen auf Attraktion durch den Schall hindeuteten. Die Ergebnisse lassen wenigstens kurzzeitige, durch Schall verursachte Verteilungsänderungen von Kabeljau in Offshorewindparks erwarten. / The growing number of offshore wind farms will lead to an increase of anthropogenic noise in the sea. Research is therefore necessary to identify and minimize any potentially negative effects of offshore wind turbine noise on fish. To examine the potential impact of offshore wind farm noise emissions on cod (Gadus morhua) and plaice (Pleuronectes platessa), tank experiments were carried out exposing the fishes to different low frequencies at sound levels as emitted by wind turbines An annular concrete tank of 10 m in diameter was divided in connected quarters by sound barriers, so that sound pressure differences of 32 to 52 dB were achieved, depending on frequency and produced sound levels. Pure tones in the frequency range between 25 and 250 Hz were artificially emitted in sound levels of 130 and 140 dB re 1µPa. The experimental fish were free to move around in the tank and therefore could avoid the highest sound levels if they chose to. The location of fish in the 24 hour periods before, during and after sound production were compared and showed significantly lower numbers of cod in the vicinity of the sound source during sound presentation in the majority of the experiments. Reactions of plaice were ambiguous, suggesting both avoidance of, or attraction to the sound. From the results at least short-term changes in distribution of cod related to sound in the vicinity of offshore wind farms could be expected.

The aim of this thesis is to evaluate different repowering alternatives from the viewpoint of increasing power production from existing offshore wind farms (OWF), as some of the first commissioned OWFs are approaching the end of their expected lifetime. The thesis presents a literature review of components and financial aspects that are of importance for repowering of OWFs. In the literature review, risks and uncertainties regarding repowering are also lifted and analysed. The thesis contains a case study on Horns Rev 1 OWF, where three different repowering scenarios are evaluated by technical and financial performance, aiming to compare the cost of repowering alternatives. The design of the case study is based around previous studies of offshore repowering having focused mainly on achieving the lowest possible levelized cost of energy (LCoE) and highest possible capacity factor, often resulting in suggested repowering utilizing smaller wind turbines than the existing ones. In order to evaluate the financial viability of repowering alternatives, the software RETScreen Expert was used to estimate the annual energy production (AEP) after losses and calculate the net present value (NPV) and LCoE for lifetime extension and full repowering utilizing different capacity wind turbines. Input values from the literature as well as real wind resource measurements from the site was utilized to achieve as accurate results as possible. The result of the case study shows that repowering of OWFs have the possibility of providing a very strong business case with all scenarios resulting in a positive NPV as well as lower LCoE than the benchmarked electricity production price. Although the initial investment cost of the different repowering alternatives presented in this thesis still are uncertain to some extent, due to the lack of reliable costs for repowering alternatives, this thesis provides a base for further research regarding the repowering of OWFs.