京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20705号 / 工博第4402号 / 新制||工||1684(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 引原 隆士, 教授 土居 伸二, 教授 松尾 哲司 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Wind energy as renewable energy will be crucial in ensuring future energy supply. Foundation for agood implementation of wind power output in the electrical grid are wind forecasts. Especially windpower ramp forecasting is important for an effective generation of wind power energy by wind parks.Wind power ramps are large changes in wind power output over a relative short amount of time. Thiswork compares two statistical definitions for four Swedish wind parks using 15 years of data from theNew European Wind Atlas data. This model provides, among other variables, the wind speed and direction at for wind power relevant height with a temporal solution of 30 min. Compared to absolutedefinitions, commonly used to define wind power ramps, a statistical definition is beneficial since it considers each site’s climatology. Based on this definition, a random forest classifier identifies wind speedand direction as the most important variables when forecasting wind power ramps. When fine-tuned, therandom forest classifier could become a valuable tool for forecasting wind power ramps.

The demand for sustainable energy generation is constantly growing and with it comes higher demands on minimizing greenhouse gas emissions. This means not only finding ways of cleaner production processes from cradle to grave but also reducing the material use, extending the lifespan of constructions and finding ways to re-use and re-cycle materials. The fastest expanding energy generation type in Sweden is wind energy. The wind turbines continue to grow in size, meaning that the foundations also need to grow in order to balance the forces they are subjugated to. The aim of this thesis is to investigate which type of windmill foundation could be more sustainable and which geotechnical parameters control the choice of foundation to later explore ways to create GIS tools that can help to map where more sustainable wind power parks can be placed. Through literature reviews and interviews with different experts in the field it was decided upon which foundation type would be considered the most economically and ecologically sustainable as well as the parameters that control the choice during the projection and construction phase. The necessary data was collected and by using ModelBuilder in ArcGIS three tools were built to, in different ways, show where would be the optimal placement of wind power parks in regard to foundation type. Rock-anchored foundations were discovered to be the most sustainable type of foundation. It uses less raw materials, minimizes the area of impact on surrounding terrain, needs the shallowest excavation, which minimizes groundwater drainage, and has a higher potential for supporting new generations of windmills. The first tool shows where it is practically feasible to place these foundations and the second tool where it is recommended to place these foundations in order to minimize risks to ecosystems and infrastructure. The third tool uses a multi-criteria evaluation method to show the optimal placement of the wind power parks in regard to distance to the electrical grid, roads and other parameters. The foundation method found to be the most economically and ecologically sustainable is the rock- anchored foundation, mainly for requiring much less material. The tools developed in ArcGIS can be used for crude estimations for placement of wind power parks but can be refined by using data with higher resolution. / Efterfrågan på hållbar energiproduktion växer ständigt och med den kommer högre krav på att minimera utsläpp av växthusgaser. Detta innebär inte bara att utveckla rena produktionsprocesser utan också minska materialanvändningen, förlänga livslängden för konstruktioner och hitta sätt att återanvända och återvinna material. Den snabbast växande energiproduktionstypen i Sverige är vindkraft. Vindkraftverken fortsätter att växa i storlek, vilket innebär att grundläggningen också behöver växa för att balansera krafterna de utsätts för. Syftet med denna avhandling är att undersöka vilken typ av grundläggningsmetod som kan vara mer hållbar och vilka geotekniska parametrar som styr valet av det, för att senare utforska sätt att skapa GIS-verktyg som kan hjälpa till att kartlägga där mer hållbara vindkraftsparker kan placeras. Genom litteraturgranskningar och intervjuer med olika experter inom området beslutades vilken grundläggningsmetod som skulle betraktas som den mest ekonomiskt och ekologiskt hållbara samt de parametrar som styr valet under projekterings- och konstruktionsfasen. De nödvändiga uppgifterna samlades in och med hjälp av ModelBuilder i ArcGIS byggdes tre verktyg för att på olika sätt visa var en optimal placering av vindkraftsparker med avseende på grundtyp kan placeras. Bergförankrad grundläggning ansågs vara den mest hållbara grundläggningsmetoden. Den använder mindre råmaterial, minimerar påverkan på omgivande terräng, behöver den grundaste utgrävningen vilket minimerar dränering av grundvatten och har en högre potential för att stödja nya generationer av vindkraftverk. Det första verktyget visar var det är praktiskt möjligt att placera dessa fundament och det andra verktyget där det rekommenderas att placera dessa fundament för att minimera riskerna för ekosystem och infrastruktur. Det tredje verktyget använder en multikriterieanalys (MCA) med flera kriterier för att visa optimal placering av vindkraftsparkerna när det gäller avstånd till elnätet, vägar och andra parametrar. Grundläggningsmetoden som har visat sig vara den mest ekonomiskt och ekologiskt hållbara är den bergförankrade grunden, främst för att den kräver mycket mindre material. Verktygen som utvecklats i ArcGIS kan användas för grova uppskattningar för placering av vindkraftsparker, men kan förfinas genom att använda data med högre upplösning.

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Detta kandidatexamensarbete syftar till att konstruera ett förslag på en lagerlösning till en generator av typen TFM [1], utvecklad av Anders Hagnestål vid KTH, som är tänkt att användas i vind- eller vågkraft. Generatorn alstrar inre elektromagnetiska krafter som ger upphov till påfrestningar på dess konstruktion, inte minst på de kullager som håller generatorns struktur på plats. Valet av lager föll på ett axialkullager i hybridutförande då den betydande delen av den elektromagnetiska kraften verkar rent axiellt. Hybridlagret består av keramiska kulor mot en kulbana av lagerstål, en kombination som motstår högre tryck än axialkullager med stålkulor. Keramiska kulor används främst för att undvika problem med elektriska urladdningar mellan lagerbana och kula, vilka uppkommer på grund av switchtransienter i strömmen från kraftelektroniksystemet. Lagrets placering i generatorn är av stor vikt, något som togs i beaktning för att minimera utböjningen i konstruktionen. Fokus har lagts på att analysera utböjningen av rotorskivan och de punkter där trycket på kullagret är som störst, dvs i kontaktytan mellan kulan och lagerbanan. Hertz yttryck användes för att beräkna kontakttrycket mellan kula och lagerbana och Finita Element Metoden för att beräkna utböjningen av rotorskivan. / The purpose of this Bachelor thesis project is the design of a bearing solution for a TFM generator [1], developed by Anders Hagnestål at KTH, suitable for windand wave power. The generator produces inner electromagnetic forces that puts stress on the generators architecture. The bearings will have an essential role in withstanding the force from the electromagnets. The most suitable solution was a hybrid axial bearing since the electromagnetic forces are mainly in the axial direction. The hybrid bearing consists of ceramic balls and a steel bearing race, a combination being able to withstand pressures better than axial bearings with steel balls. Ceramic balls are mainly used to avoid electrical discharges between the bearing race and balls. These discharges occur due to switchtransients in the current from the powerelectronic system. The placement of the bearing in the generator is of great importance and has to be considered to minimize the displacement of the rotor discs. The project is focused on analyzing the displacement of the rotor disc and the area with greatest pressure in the bearing, this area occurs in the contact point between the ceramic ball and the steel bearing race. Hertzian contact pressure was used for the contact pressure between the ball and the bearing race and the Finite Element Method for calculating the displacement of the rotor disc.

In last decade, there is a large increase in installed capacity of wind power. Asmore wind power is integrated into utility networks, related technologychallenges draw much attention. The doubly fed induction generator (DFIG) isthe mainstream choice for wind turbine generator (WTG) in current market andthe object of this thesis. It is very sensitive to voltage dips. The enhancement oflow voltage ride through (LVRT) is one of the most important issues for DFIG,and many works have already been done to provide solutions.In current works, the voltage dip waveforms that are applied in LVRTrelated works are largely different from waveforms in reality, because they failto consider the the effect of realistic wind farm configurations on waveforms ofvoltage dips and significant influences of additional characteristics of voltagedips. The true impact of the voltage dip needs to be assessed in performanceevaluation and development of LVRT methods. To support the development ofpractical LVRT capacity enhancement solutions, the application of voltage dipknowledge is definitely demanded.In this thesis, the characteristics of realistic waveform voltage dips in windfarm are analyized based on voltage dip knowldege from power quality field,measured voltage dip from industry and realistic wind farm configurations.Classical analysis theory is applied to explain the principles of the impact ofvoltage dip characteristics on dynamic behavior of DFIG. The impacts of manywidely neglected characteristics such as phase angle jump (PAJ), point on wave(POW) of initiation and recovery, voltage recovery process, transformerconfigurations, load effect are revealed and verified by simulations. The impactof many voltage dip characteristics on DFIG are studied for the first time. / De senaste tio åren har sett en stor ökning av installerad effekt av vindkraft.Mer vindkraft i elnäten har lett till större uppmärksamhet om dess tekniskautmaningar. Den dubbelmatad asynkrongenerator (DFIG) är idag denvanligaste förekommande typen i vindkraftverk. Den är mycket känslig förspänningssänkningar. Förbättring av tålighet för spänningssänkningar (LVRT)är en av de viktigaste frågorna för DFIG, och många studier har redan söktlösningar.I befintliga studier om LVRT har spänningssänkningarna skiljt sig väsentligtfrån verkliga vågformer, då de inte har tagit hänsyn till realistiskavindparkkonfigurationer och betydande påverkan av ytterligare egenskaper hosspänningssänkningar. För att stödja utvecklingen av praktiska LVRT lösningarbehövs mer kunskap om spänningssänkningar för att bedöma dess verkligainverkan.Detta examensarbete förbättrar LVRT analysen av DFIG genom att tillämpakunskap om spänningssänkningar från elkvalitetsområdet, tillsammans medrealistiska vindparkskonfigurationer. Inflytandet av ändringar i fasvinkel(PAJ), fasvinkeln vid sänkning och återhämtning (POW), spänningsåterhämtning, transformatorkonfigurationer, last och många andra egenskaperav spänningssänkningar ingår också. Inflytandet av många egenskaper avspänningssänkningar studeras här akademiskt för första gången. Denkaraktäristik av realistiska spänningssänkningar som inträffar vid generatornspoler, och de effekter dessa har, studeras och förklaras genom teoretisk analysoch intensiva simuleringar.

Wind power often is a source of voltage fluctuations and possible voltage issues are raised when considering interconnecting wind turbines to an electric grid. Also, the power electronics introduced in the wind turbines might insert more fluctuations and different PQ problems. Distributed generation seems to be a good option in order to try to mitigate these problems. The first goal of the work is to create a model of a small electric grid, using MATLAB/Simulink. The models aims to simulate various DFIG wind turbines coupled to the grid in different conditions of location and wind. Then, the main objective is to analyze the PQ in the grid with this type of turbine. For this, once the simulations have been done, the results obtained have allowed calculating different indices to study PQ in the model. Afterwards, a comparison of those indices in the different conditions is made. / StandUp

Wind energy is a means of energy production without carbon emissions, facilitating regional and national energy security. While there are currently no offshore wind farms in the United States, there has been growing success in building land-based wind capacity. Within the wind industry, there is a call for a streamlined permitting process, as well as an objective evaluation of current stakeholder processes. Within city and regional planning, the stakeholder process and public participation in general have long been subject to research and discourse, as scholars and practitioners alike seek to identify and typify what exactly makes public participation robust or rigorous. In Europe, researchers have found that a stakeholder process characterized by early inclusion and local decision-making increases community acceptance of large-scale wind projects, and that a ‘soft-path’, decentralized approach to infrastructure development, as seen in Germany, leads to greater community acceptance as well, versus the ‘hard-path’, centralized approach to infrastructure development as typified in early Dutch wind development. While the public process should not supplant the formal permitting process, or detract from technical expertise, a better understanding of what type of siting and decision-making process are construed by participants as positive or negative could help to formulate stakeholder involvement more effectively in future projects. It could also help to decrease the length of permitting times by promoting consensus-building rather than inadvertently creating an adversarial decision-making climate. This thesis uses a case study methodology to compare three land-based wind farms in Massachusetts and Vermont. It also compares the wind development policies between the two states. From each site, stakeholders are identified and interviewed concerning their experiences and perspectives of the stakeholder or public process. Interviews are analyzed using a matrix composed of success criteria pulled from the fields of regional planning and public participation theory, collaborative planning, and adaptive resource management. Findings include evidence as to what degree there was a stakeholder process, and to what degree participants found it positive or negative. The research found that the characteristics and practices of ore robust or rigorous stakeholder engagement are largely lacking in New England land-based wind development. These characteristics or practices included third-party data collection and reporting; early and broad stakeholder inclusion; collaborative ground rule setting; and no third-party mediation or facilitation. Stakeholder process perspectives are easily divided by wind-energy attitudes: anti-wind stakeholders reported greater antipathy toward the process, whereas proponents of both specific projects and the technology in general reported greater favorability toward the process and outcome. Vermont and Massachusetts have distinct wind development processes and distinct mechanisms for public participation and stakeholder engagement in a renewable energy technology context. In many ways, the siting of renewable infrastructure still follows the ‘decide, announce, defend’ character of conventional infrastructure and facility siting. Wind proponents, and proponents of other renewable energy technologies and sustainability measures in general, should pause and consider how to craft meaningful, robust and rigorous stakeholder processes prior to site selection and development. This will lend legitimacy to both the process and technology, lending political and social sustainability to a technology that is well needed for social, economic and environmental well-being. Continued avoidance of early and robust stakeholder engagement may contribute to ongoing conflict and confusion regarding renewable energy siting, permitting and development. Stakeholder experiences and perspectives also demonstrated that there are many factors contributing to public and social perceptions of wind technology and specific projects, including the financial gain or reward to communities and stakeholders; the size of individual turbines; project ownership and management; and project scale. There is opportunity for enhancing the public process and allowing rigorous and robust stakeholder process in wind energy development.

Climate change drives policymakers to reduce emissions and enhance the integration of variable renewable energy sources (VRES) into the power system. Wind power is considered among the most beneficial VRES as it can generate cost-effectively carbon-free electricity but comes with inherent intermittency. Hydropower is a proposed solution among the research community to handle VRES output volatility and ensure balanced energy output to the electricity grid. This thesis addresses the problem by investigating the integration of intermittent wind power into a hydropower system cost-effectively. The research question "How does the integration of wind power affect the hydro operations and the cost of purchased electricity?" is answered within the Design Science Research framework by optimizing a subset of the Røldal-Suldal hydropower system in Norway's NO2 region. The cost-minimization model utilizes historical data from 2018 on water inflows, hourly electricity prices, hourly wind production, and hourly energy consumption for a smelter within the NO2 zone. To reduce the 8,760-time steps and computational concerns, the kmeans clustering algorithm is implemented to obtain four representative weeks. A multiperiod linear programming model is structured to assess the joint operation of wind and hydropower while ensuring a minimum energy production to satisfy the system's power demands. A benchmark scenario with no wind capacity is formed to serve as the basis for comparisons. Ten scenarios with 100-MW incremental steps of wind capacity are implemented. The minimized cost for the benchmark scenario is €104,981,312.34, with electricity purchases covering more than 75% of the energy demand and hydropower satisfying the remaining 25%. Adding 100 MW of wind capacity reduces costs by more than €2,000,000, restricting the purchased energy’s share by 1.49%, which is the equivalent increased share of wind power during each incremental step. A wind capacity of 1,000 MW leads to a 21.24% cost reduction. Hydropower production remains unaffected by the wind integration based on terminal values of reservoir level or turbined water volume. However, the distribution of hydropower production throughout the year changes after installing wind capacity enabling hydropower to utilize stored water optimally to minimize the costs of purchasing energy. A sensitivity analysis to assess the uncertainties tied with the model coefficients shows that increasing initial reservoir levels and adding 1,000 MW of wind capacity is the most influential factor in the optimization model.

Thesis: M.S., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 1977 / Includes bibliographical references. / M.S. / M.S. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science