Le but de cette thèse est l'optimisation de la production de l'électricité renouvelable pour site isolé de faible puissance. Un système, utilisant deux sources renouvelables : photovoltaïque et éolienne, est étudié afin d'améliorer le rendement énergétique de l'énergie produite. Pour la chaîne de conversion photovoltaïque, un contrôleur pour suivre le point de puissance maximale est conçu en utilisant l'approche de recherche directe (méthode Perturbe & Observe) combinée avec la logique floue, tout en prenant en compte le sens de variation des perturbations. Avec cette combinaison, on peut éviter des défauts de la méthode Perturbe & Observe, s'affranchir des informations sur les caractéristiques du panneau photovoltaïque et des conditions climatiques. Egalement, pour la chaîne de conversion éolienne de petite puissance fonctionnant à vitesse variable couplée à un générateur synchrone à aimant permanent, un contrôleur pour suivre le point de puissance maximale est proposé qui est basé sur le même principe par rapport à la chaîne de conversion photovoltaïque. Cette approche proposée a l'avantage de l'utilisation d'un capteur de tension au lieu d'un capteur de vitesse, ceci présente un intérêt certain notamment pour sites isolés par rapport aux autres solutions. Enfin, pour la réalisation d'un système de production d'électricité hybride, un superviseur est conçu pour obtenir un comportement optimal du système en fonction des variations de la charge et de la production en prenant en compte du système de stockage et de délestage. Pour chaque point abordé, des études en simulation sont fournies pour montrer l'efficacité des approches proposées. / The objective of this thesis is to optimize the production of renewable electricity for small isolated network. A system using two renewable sources: solar and wind power, is studied in order to improve the efficiency of energy extracted. For the photovoltaic conversion system, a maximum power point tracking controller is designed using direct searching approach (method Perturbe & Observe) combined with fuzzy logic, taking into account the direction of perturbation. This combination can avoid the disadvantages of the method Perturbe & Observe, and not requires any information about the generator's characteristics or climate conditions. Similarly, for the variable speed wind turbine using permanent magnet synchronous generator, a controller to track the maximum power point, based on the same principle with photovoltaic conversion system, is proposed. This approach has the advantage of using a voltage sensor instead of a speed sensor, this presents a particular interest for stand-alone system comparing to other solutions. Finally, for the realization of hybrid generation system, a fuzzy supervisor is adapted to obtain an optimal behavior of the system according to the variations of load demand and extracted power, taking into account the storage and dissipation system. For each issue, simulation studies are provided to show the effectiveness of the proposed approaches.

Given increasing problems in the availability, affordability and deliverability of commercial primary and secondary energy resources, coupled with growing macroeconomic uncertainties, the use of renewable, non-commercial energy resources has been actively promoted in rural areas of developing countries. This, in addition to the fact that conventional, 'state-of-the-art' energy facilities present technical problems, are inequitable and pose potential environmental hazards, has led to proposals for instituting alternative, intermediate or 'appropriate' technologies in rural settlements. This thesis identifies technical, economic, social, cultural and institutional barriers to the introduction of intermediate or 'appropriate' technologies in rural areas. The cases of solar and biogas technologies in Korea, Malaysia, Papua New Guinea the Philippines and Thailand are considered. Policy and planning process recommendations are made on the roles of government, voluntary aid-agencies and the rural user, to overcome the obstacles to implementing these technologies. These recommendations cover the micro (village) and macro (regional and national) levels over two time horizons, and stress the need for a comprehensive approach to discerning rural needs, followed by integrated technology diffusion through effective program and project implementation. In addition, this thesis identifies the need for a continuous collection of information on rural socio-economic conditions and potential for rural interfuel substitution and finally, recommends research into improving technical efficiencies of alternative energy technologies such as solar and biogas. Alternative or intermediate energy technologies such as solar and biogas can play an important role in augmenting rural energy supply. Unless steps are taken to remove the identified barriers to implementation in future technology diffusion efforts, this potential will not be realized. Policy and planning process recommendations made in this thesis present means through which these barriers could be removed. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate

M.Phil. ( Energy Studies) / In contrast to conventional energy sources, the advantage of renewable energy lies in the fact that it is virtually inexhaustible and that its utilisation is accompanied by minima environmental pollution. I t is, furthermore, very appropriate especially seen in the light of the large Third World component of the South African energy economy. It therefore becomes necessary to evaluate the adequacy of Government strategy as far as the optimal development and utilisation of the renewable energy sources with the best potential in South Africa are concerned, against present and future needs for and the utilisation possibilities of these sources...

abstract: The operating temperature of photovoltaic (PV) modules has a strong impact on the expected performance of said modules in photovoltaic arrays. As the install capacity of PV arrays grows throughout the world, improved accuracy in modeling of the expected module temperature, particularly at finer time scales, requires improvements in the existing photovoltaic temperature models. This thesis work details the investigation, motivation, development, validation, and implementation of a transient photovoltaic module temperature model based on a weighted moving-average of steady-state temperature predictions. This thesis work first details the literature review of steady-state and transient models that are commonly used by PV investigators in performance modeling. Attempts to develop models capable of accounting for the inherent transient thermal behavior of PV modules are shown to improve on the accuracy of the steady-state models while also significantly increasing the computational complexity and the number of input parameters needed to perform the model calculations. The transient thermal model development presented in this thesis begins with an investigation of module thermal behavior performed through finite-element analysis (FEA) in a computer-aided design (CAD) software package. This FEA was used to discover trends in transient thermal behavior for a representative PV module in a timely manner. The FEA simulations were based on heat transfer principles and were validated against steady-state temperature model predictions. The dynamic thermal behavior of PV modules was determined to be exponential, with the shape of the exponential being dependent on the wind speed and mass per unit area of the module. The results and subsequent discussion provided in this thesis link the thermal behavior observed in the FEA simulations to existing steady-state temperature models in order to create an exponential weighting function. This function can perform a weighted average of steady-state temperature predictions within 20 minutes of the time in question to generate a module temperature prediction that accounts for the inherent thermal mass of the module while requiring only simple input parameters. Validation of the modeling method presented here shows performance modeling accuracy improvement of 0.58%, or 1.45°C, over performance models relying on steady-state models at narrow data intervals. / Dissertation/Thesis / Masters Thesis Engineering 2020

Wind power generation has gained a large share in the renewable energy market over the past few years. This study investigates the impact of large scale penetration of permanent magnet synchronous generator (PMSG) based wind turbines on power quality of the grid. PMSGs are attractive due to the absence of a gearbox in the drive-train, which results in lower maintenance costs and higher reliability. Moreover, the advancements in power electronics have facilitated PMSGs to generate optimal power at varying wind speed conditions. This is achieved through the use of maximum power point tracking algorithms. The drawbacks of PMSG-based wind energy systems are that they inject harmonics into the network and cause flicker as well as other power quality issues. Despite these disadvantages, the grid code requires that PMSGs stay connected to the grid even under grid disturbances. This is because the reactive power control capability of PMSG-based wind energy systems can actually assist with voltage support. It will be shown in this study that disconnecting large scale PMSGs based wind turbines during grid disturbances has a detrimental effect on transient stability of the grid. This study will show that PMSG-based wind energy systems improve transient stability and assist in voltage support through reactive power control. Moreover, the impacts of large scale PMSG based wind turbines on power quality of the grid can be reduced by various means, which are also addressed in the study.

Philosophiae Doctor - PhD / Today fossil fuels such as oil, coal and natural gas are providing for our ever growing energy needs. As the world’s fossil fuel reserves fast become depleted, it is vital that alternative and cleaner fuels are found. Renewable energy sources are the way of the future energy needs. A solution to the looming energy crisis can be found in the energy carrier hydrogen. Hydrogen can be produced by a number of production technologies. One hydrogen production method explored in this study is electrolysis of water.

State policy incentives for solar power have grown significantly in the past several years. This paper examines the effectiveness of policy incentives to increase residential solar PV capacity. County-level solar adoption data and controls for demographic characteristics, solar resources, and pro-environmental preferences are used to estimate a model of residential solar adoption. Empirical findings show that financial incentives, solar-specific mandates, and loan financing programs are important drivers of residential PV capacity growth. Incentives that reduce the up-front cost of adoption and that are subject to low uncertainty are found to have the largest impact. Results also point to a significant positive relationship between hybrid vehicle sales and residential PV capacity growth, indicating the importance of pro-environmental preference as a predictor of solar PV demand.

京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第23294号 / エネ博第419号 / 新制||エネ||79(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 手塚 哲央, 教授 宇根﨑 博信, 准教授 MCLELLAN Benjamin / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Microgrid is an essential part of the nation’s smart grid deployment plan, recognized especially for improving efficiency, reliability, flexibility, and resiliency of the electricity system. Since microgrid consists of different distributed generation units, microgrid scheduling and real-time dispatch play a crucial role in maintaining economic, reliable, and resilient operation. The control and optimization performances of the existing online approaches degrade significantly in microgrid applications with missing forecast information, large state space, and multiple probabilistic events. This dissertation focuses on these challenges and proposes efficient online learning and optimization-based approaches. For addressing the missing forecast challenges on online microgrid operations, a new fitted rolling horizon control (fitted-RHC) approach is proposed in Chapter 2. The proposed fitted-RHC approach is designed with a regression algorithm that utilizes the empirical knowledge obtain from the day-ahead forecast to make microgrid real-time decisions whenever the intra-day forecast data is unavailable. Simulation results show that the proposed fitted-RHC approach can achieve the optimal policy for the deterministic case study and perform efficiently with the uncertain environment in the stochastic case study. / Includes bibliography. / Dissertation (PhD)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Sustainable energy has taken center stage in materials research and global markets, which has encouraged an explosion in related materials development. Practical implementations of sustainable energy solutions rely upon high-performance and cost-effective materials for energy harvesting and storage. Organic electronics, a class of materials composed principally of carbon, are regarded as promising candidates in this respect. Carbon, when arranged with atomic precision and warped carefully into desirable conformations, can generate exceptionally inexpensive and high-performance materials. These materials can then be readily integrated into solar cells, capacitors, and transistors. This dissertation explores our progress in the field of high-performance organic electronics in the context of these practical devices, and aims to establish simple design principles for the future development of contorted organic electronics. Of principal importance to this thesis is the conclusion that localized molecular contortion seems to bestow unique and somewhat unexpected properties upon extended systems. Therefore, a key theme underlying our work herein is the idea that for specific applications, contorted or extended graphene nanoribbons can be shown to be superior to planar organics. This advantage has allowed us to report exceptionally high performance metrics in the fields of energy harvesting and storage. Chapter 1 comprises an overview of the entire body of work contained within this dissertation, in a highly condensed format. This includes in-depth specific background on the innovations of prior researchers who have enabled our present work. Chapter 2 details the elongation of the small graphene fragment perylene into long, electronically active, and ambient-stable nanoribbons. This chapter is assembled from three research manuscripts investigating the employment of these nanoribbons as electron transporting materials in photovoltaics and one set of preliminary results on their incorporation as potential surface arrays for chip technologies. Chapter 3 examines the expansion of our perylene-based nanoribbons into large single-molecule three-dimensional nanostructures up to 5 nm in wingspan. These structures, by consequence of their three-dimensional geometry and contorted nature, exhibit curious enhancements over their one-dimensional counterparts. Such enhancements, namely in photovoltaic efficiency and electron transport behavior, are investigated over the course of two research manuscripts. Chapter 4 explores the idea of organic energy storage through the lens of pseudocapacitance, and further expands the perylene toolbox by developing high-capacitance and highly stable polymer structures. These ideas ultimately culminate in the final subchapter, wherein our most recent work on contorted, semi-two-dimensional capacitive polymers is disclosed. The exceptionally strong and potentially economically viable results of our most recent energy storage architecture are enabled entirely by our understanding of molecular contortion. Namely, contortion’s unique ability to manifest long-range electronic conjugation concomitant with the prevention of aggregation, thus improving surface area for ion diffusion and bulk processability. In consideration of the impact these nanoscale ideas could have on the global scale, it is our belief that ideas concerning contortion within the context of organic electronics will continue to generate high-performance energy storing and harvesting materials. Our explorations towards such solutions have garnered substantial interest in the materials community thus far, and this dissertation seeks to add to that growing body of literature by inspiring numerous new twisted architectures.