Dissertations / Theses on the topic 'Energy conversion systems'
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Thorburn, Karin. "Electric Energy Conversion Systems : Wave Energy and Hydropower." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7081.
Full textMuralidharan, Shylesh. "Assessment of ocean thermal energy conversion." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76927.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 103-109).
Ocean thermal energy conversion (OTEC) is a promising renewable energy technology to generate electricity and has other applications such as production of freshwater, seawater air-conditioning, marine culture and chilled-soil agriculture. Previous studies on the technology have focused on promoting it to generate electricity and produce energy-intensive products such as ammonia and hydrogen. Though the technology has been understood in the past couple of decades through academic studies and limited demonstration projects, the uncertainty around the financial viability of a large-scale plant and the lack of an operational demonstration project have delayed large investments in the technology. This study brings together a broad overview of the technology, market locations, technical and economic assessment of the technology, environmental impact of the technology and a comparison of the levelized costs of energy of this technology with competing ones. It also provides an analysis and discussion on application of this technology in water scarce regions of the world, emphasized with a case study of the economic feasibility of this technology for the Bahamas. It was found that current technology exists to build OTEC plants except for some components such as the cold water pipe which presents an engineering challenge when scaled for large-scale power output. The technology is capital intensive and unviable at small scale of power output but can become viable when approached as a sustainable integrated solution to co-generate electricity and freshwater, especially for island nations in the OTEC resource zones with supply constraints on both these commodities. To succeed, this technology requires the support of appropriate government regulation and innovative financing models to mitigate risks associated with the huge upfront investment costs. If the viability of this technology can be improved by integrating the production of by-products, OTEC can be an important means of producing more electricity, freshwater and food for the planet's increasing population.
by Shylesh Muralidharan.
S.M.in Engineering and Management
Ahmed, Shehab. "Compact harsh environment energy conversion systems." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1289.
Full textBoström, Cecilia. "Electrical Systems for Wave Energy Conversion." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-140116.
Full textFelaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 727
Michas, Marios. "Control of turbine-based energy conversion systems." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/117586/.
Full textOh, Sang Joon. "Electromagnetics of inertial energy storage systems with fast electromechanical energy conversion /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Full textMcEnaney, Kenneth. "Thermoelectrics and aerogels for solar energy conversion systems." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97770.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 115-124).
Concerns about climate change, the world's growing energy needs, and energy independence are driving demand for solar energy conversion technologies. Solar thermal electricity generation has the potential to ll this demand. Solar thermal technology could also be used to displace fossil fuels in applications which require heat as an input. This thesis addresses the potential of two solar thermal technologies: solar thermoelectric generators and aerogel-based solar thermal receivers. Thermoelectrics are materials which produce a voltage when subjected to a temperature gradient. In a solar thermoelectric generator (STEG), sunlight heats one end of the thermoelectric materials, generating a voltage across the device. The voltage can be connected to a load and useful work can be extracted. By adding optical concentration and using higher-temperature materials, the power output and energy conversion eciency of STEGs can be increased. In this work, segmented thermoelectric generators (TEGs) made of bismuth telluride and skutterudite alloys are modeled, optimized, built, and tested. These TEGs achieve a heat-to-electricity conversion efficiency of 10.7% at a hot side of 550° C, the highest TEG eciency reported in this temperature range. From these TEGs, STEGs are built which achieve a sunlight-to-electricity conversion eciency of 5.7% at less than 60 suns, higher than the best reported literature values in this concentration range. With further improvements, it is projected that these STEGs will achieve 10% eciency at 100 suns. In any type of solar thermal system, heat losses from the system must be suppressed to achieve high eciency. Aerogels, which are stable ultra-low density foams, can suppress radiative and convective losses. It is shown that aerogel-based solar thermal receivers can increase the eciency of traditional solar thermal electricity and hot water generation. These results can help advance the field and expand the scope of solar thermal technologies.
by Kenneth McEnaney.
Ph. D.
Yassin, Ali M. "Functional conjugated systems for energy conversion and storage." Angers, 2011. http://www.theses.fr/2011ANGE0080.
Full textThis work entitled « Functional Conjugated Systems for Energy Conversion and Storage » involves the design and synthesis of new classes of functional π-conjugated systems for photovoltaic conversion and the development of new microporous materials. After a general introduction to the structure and electronic properties of the major classes of conjugated systems and more particularly conjugated molecules used as donor material in organic solar cells (OSC), the second chapter describes the synthesis and study of a series of molecular donors obtained by grafting dicyanovinylene on three types of conjugated rigid blocks : carbazole, cyclopentadithiophene and dithienopyrrole (DTP). The evaluation of these systems in donor-acceptor bilayer heterojunction OSCs shows that the DTP leads to best results. A study of the evolution of the electronic properties, of a series of oligo-DTPs, with the chain length further confirms the interest of the donor block for low band gap conjugated systems. The next chapter deals with the synthesis of a series of conjugated molecules of donor-acceptor-donor (D-A-D) type, built around a core of isoindigo, and describes a first evaluation of their potential as donor materials in OSCs. The fourth chapter deals with the synthesis of a series of 3D molecules derived from the grafting of donor groupas on a quaterthiophene core with a quasi-tetrehedral geometry caused by steric effect, and examine the relationship between the structure of the molecules, the mobility of positive charges in these materials and their performance in OSCs. Finally the fift and last chapter describes the first steps towards the design and use of 3D conjugated molecules in order to develop new classes of electro-active materials by polymerization of microporous 3D molecular systems provided with reactive end groups
Buehrle, Bridget Erin. "Modeling of Small-Scale Wind Energy Conversion Systems." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/50920.
Full textThe study of the diffuser augmented wind turbine provides optimum dimensions for achieving high power density that can address the challenges associated with small scale wind energy systems; these challenges are to achieve a lower start-up speed and low wind speed operation. The diffuser design was modeled using commercial computational fluid dynamics code. Two-dimensional modeling using actuator disk theory was used to optimize the diffuser design. A statistical study was then conducted to reduce the computational time by selecting a descriptive set of models to simulate and characterize relevant parameters\' effects instead of checking all the possible combinations of input parameters. Individual dimensions were incorporated into JMP® software and randomized to design the experiment. The results of the JMP® analysis are discussed in this paper. Consistent with the literature, a long outlet section with length one to three times the diameter coupled with a sharp angled inlet was found to provide the highest amplification for a wind turbine diffuser.
The second study consisted of analyzing the capabilities of a small-scale vertical axis wind turbine. The turbine consisted of six blades of extruded aluminum NACA 0018 airfoils of 0.08732 m (3.44 in) in chord length. Small-scale wind turbines often operate at Reynolds numbers less than 200,000, and issues in modeling their flow characteristics are discussed throughout this thesis. After finding an appropriate modeling technique, it was found that the vertical axis wind turbine requires more accurate turbulence models to appropriately discover its performance capabilities.
The use of tubercles on aerodynamic blades has been found to delay stall angle and increase the aerodynamic efficiency. Models of 440 mm (17.33 in) blades with and without tubercles were fabricated in Virginia Tech\'s Center for Energy Harvesting Materials and Systems (CEHMS) laboratory. Comparative analysis using three dimensional models of the blades with and without the tubercles will be required to determine whether the tubercle technology does, in fact, delays the stall. Further computational and experimental testing is necessary, but preliminary results indicate a 2% increase in power coefficient when tubercles are present on the blades.
Master of Science
Trilla, Romero Lluís. "Power converter optimal control for wind energy conversion systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/134602.
Full textWind energy has increased its presence in many countries and it is expected to have even a higher weight in the electrical generation share with the implantation of offshore wind farms. Consequently, the wind energy industry has to take greater responsibility towards the integration and stability of the power grid. In this sense, there are proposed in the present work control systems that aim to improve the response and robustness of the wind energy conversion systems without increasing their complexity in order to facilitate their applicability. In the grid-side converter it is proposed to implement an optimal controller with its design based on H-infinity control theory in order to ensure the stability, obtain an optimal response of the system and also provide robustness. In the machine-side converter the use of a Linear Parameter-Varying controller is selected, this choice provides a controller that dynamically adapts itself to the operating point of the system, in this way the response obtained is always the desired one, the one defined during the design process. Preliminary analysis of the controllers are performed using models validated with field test data obtained from operational wind turbines, the validation process followed the set of rules included in the official regulations of the electric sector or grid codes. In the last stage an experimental test bench has been developed in order to test and evaluate the proposed controllers and verify its correct performance.
Anheden, Marie. "Analysis of gas turbine systems for sustainable energy conversion." Doctoral thesis, KTH, Chemical Engineering and Technology, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2914.
Full textIncreased energy demands and fear of global warming due tothe emission of greenhouse gases call for development of newefficient power generation systems with low or no carbondioxide(CO2) emissions. In this thesis, two different gasturbine power generation systems, which are designed with theseissues in mind, are theoretically investigated and analyzed.Inthe first gas turbine system, the fuel is combusted using ametal oxide as an oxidant instead of oxygen in the air. Thisprocess is known as Chemical Looping Combustion (CLC). CLC isclaimed to decrease combustion exergy destruction and increasethe power generation efficiency. Another advantage is thepossibility to separate CO2without a costly and energy demanding gasseparation process. The system analysis presented includescomputer-based simulations of CLC gas turbine systems withdifferent metal oxides as oxygen carriers and different fuels.An exergy analysis comparing the exergy destruction of the gasturbine system with CLC and conventional combustion is alsopresented. The results show that it is theoretically possibleto increase the power generation efficiency of a simple gasturbine system by introducing CLC. A combined gas/steam turbinecycle system with CLC is, however, estimated to reach a similarefficiency as the conventional combined cycle system. If thebenefit of easy and energy-efficient CO2separation is accounted for, a CLC combined cyclesystem has a potential to be favorable compared to a combinedcycle system with CO2separation.
In the second investigation, a solid, CO2-neutral biomass fuel is used in a small-scaleexternally fired gas turbine system for cogeneration of powerand district heating. Both open and closed gas turbines withdifferent working fluids are simulated and analyzed regardingthermodynamic performance, equipment size, and economics. Theresults show that it is possible to reach high power generationefficiency and total (power-and-heat) efficiency with thesuggested system. The economic analysis reveals that the costof electricity from theEFGT plant is competitive with the moreconventional alternatives for biomass based cogeneration in thesame size range (<10 MWe).
Keywords:power generation, Chemical Looping Combustion,CO2separation, oxygen carrier, biomass fuel, closedcycle gas turbine, externally fired gas turbine
Mendonca, Jose Manuel de Araujo Baptista. "Microcomputer on-line control of wind energy conversion systems." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38101.
Full textRen, Yaxing. "Perturbation estimation based control of electric energy conversion systems." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3005548/.
Full textTsujimura, Seiya. "Studies on energy conversion systems based on bioelectrocatalytic reactions." Kyoto University, 2007. http://hdl.handle.net/2433/59291.
Full text0048
新制・論文博士
博士(農学)
乙第12049号
論農博第2636号
新制||農||944(附属図書館)
学位論文||H19||N4268(農学部図書室)
UT51-2007-H604
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 加納 健司, 教授 清水 昌, 教授 坂田 完三
学位規則第4条第2項該当
Presby, Andrew L. "Thermophotovoltaic energy conversion in space nuclear reactor power systems." Thesis, Monterey, Calif. : Naval Postgraduate School, 2004. http://edocs.nps.edu/npspubs/scholarly/theses/2004/Dec/04Dec%5FPresby.pdf.
Full textThesis Advisor(s): Gopinath, Ashok ; Michael, Sherif. "December 2004." Description based on title screen as viewed on March 13, 2009. Includes bibliographical references (p. 123-127). Also available in print.
FORCINETTI, RENATO. "MAGNETO-FLUID-DYNAMIC ENERGY CONVERSION SYSTEMS FOR AEROSPACE APPLICATIONS." Doctoral thesis, Università degli Studi di Cagliari, 2017. http://hdl.handle.net/11584/249563.
Full textCarpintero, Moreno Efrain. "Wave energy conversion based on multi-mode line absorbing systems." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/wave-energy-conversion-based-on-multimode-line-absorbing-systems(dc39c038-c89e-4243-be4c-062a6e27be5b).html.
Full textTopal, Emre Tan. "A Mems Thermoelectric Energy Harvester For Energy Generation In Mobile Systems." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613636/index.pdf.
Full textT values. The performance of the MEMS TE energy harvesters was optimized using analytical and 3-D finite element models. An analytical code was used for profiling the electrical power output with varying geometry. The design points with maximum generated power were selected, and the microfabricated thermoelectric energy harvesters were designed accordingly. The fabricated devices are formed on a silicon wafer and composed of Nickel and Chromium thermocouples on SiO2/Si3N4 diaphragms, and Titanium heater and monitor resistors for testing purposes. Microfabrication was followed by the performance characterization of MEMS TE energy harvesters with the conducted tests. For 10 °
C temperature difference between the hot and cold junctions (a heat source at 35 °
C), the proposed TE energy harvesters are capable of providing 1.1 µ
W/cm2 power density and 1.71 V voltage. The performance of the thermoelectric generators in general is limited by Carnot cycle efficiency. Nevertheless, the validated practical performance of MEMS TE energy harvesters proposed in this thesis is comparable to other examples in literature. It is anticipated by the calculations that this design will be able to provide the highest thermoelectric efficiency factor (4.04 µ
W/K2cm2) among the lateral TE energy harvesters if thermoelectric materials having high Seebeck coefficient values (such as p-Si, n-Si, polysilicon, Bi2Te3 etc.) are used. According to the performance results, the MEMS TE energy harvesters can be implemented in mobile systems to convert waste heat into electricity. The fabrication process can be adapted to CMOS with some modifications if needed. The lateral MEMS thermoelectric energy harvesters can also be combined with vibration energy harvesters to realize multi-mode energy scavenging. For prospective study, vertical thermoelectric generator configurations are also discussed in order to further increase the power density generated. The finite element simulations for proposed vertical configurations with air and water convection were completed. The vertical TE generators proposed can supply up to 4.2 mW/cm2 with a heat source at a temperature of 310 K.
Wu, Feng. "Modelling and control of wind and wave energy conversion systems." Thesis, University of Birmingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525483.
Full textMelville, Guy T. "Hydrodynamic and economic modelling of tidal current energy conversion systems." Thesis, Robert Gordon University, 2008. http://hdl.handle.net/10059/695.
Full textMacRae, Angus Neil. "Economic and cost engineering aspects of wind energy conversion systems." Thesis, Robert Gordon University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258961.
Full textMacmillan, Susan. "An appraisal of wind energy conversion systems for agricultural enterprises." Thesis, Robert Gordon University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330282.
Full textZoric, I. "Multiple three-phase induction generators for wind energy conversion systems." Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/8387/.
Full textGhosh, Suvradip. "Energy and data conversion circuits for low power sensory systems." Thesis, University of Missouri - Kansas City, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3610195.
Full textThis dissertation focuses on the problem of increasing the lifetime of wireless sensors. This problem is addressed from two different angles: energy harvesting and data compression. Energy harvesting enables a sensor to extract energy from its environment and use it to power itself or recharge its batteries. Data compression, on the other hand, allows a sensor to save energy by reducing the radio transmission bandwidth.
This dissertation proposes a fractal-based photodiode fabricated on standard CMOS process as an energy harvesting device with increased efficiency. Experiments show that, the fractal based photodiodes are 6% more efficient compared to the conventional square shaped photodiode. The fractal shape photodiode has more perimeter-to-area ratio which increases the lateral response, improving its efficiency.
With increased efficiency, more current is generated but the open-circuit voltage still remains low (0.3V–0.45V depending on illumination condition). These voltages have to be boosted up to higher values if they are going to be used to power up any sensory circuit or recharge a battery. We propose a switched-inductor DC-DC converter to boost the low voltage of the photodiodes to higher voltages. The proposed circuit uses two on-chip switches and two off-chip Components: an inductor and a capacitor. Experiments show a voltage up to 2.81V can be generated from a single photodiode of 1mm2 area. The voltage booster circuit achieved a conversion efficiency of 59%.
Data compression was also explored in an effort to reduce energy consumption during radio transmission. An analog-to-digital converter (ADC), which can jointly perform the tasks of digital conversion and entropy encoding, has also been proposed in this dissertation. The joint data conversion/compression help savings in area and power resources, making it suitable for on-sensor compression. The proposed converter combines a cyclic converter architecture and Golomb-Rice entropy encoder. The converter hardware design is based on current-mode circuits and it was fabricated on a 0.5 μm CMOS process and tested. Experiment results show a lossless compression ratio of 1.52 and a near-lossless compression of 5.2 can be achieved for 32 × 32 pixel image.
Deal, Michael William. "Net Primary Production in Three Bioenergy Crop Systems Following Land Conversion." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1309362383.
Full textZhang, Zhen, and 張鎮. "Advanced control and analysis of energy conversion systems for electric vehicles." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206458.
Full textpublished_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
Greenhut, Andrew David. "Modeling and analysis of hybrid geothermal-solar thermal energy conversion systems." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58087.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 116-118).
Innovative solar-geothermal hybrid energy conversion systems were developed for low enthalpy geothermal resources augmented with solar energy. The goal is to find cost-effective hybrid power cycles that take advantage of the potential synergies of solar thermal and geothermal resources. One aspect is to determine the hybrid configuration that yields the highest annualized electricity generation. The levelized cost of electricity (LCOE) is estimated using equipment costing rules of thumb developed from Aspen HTFS and Aspen ICARUS software and from other sources. Detailed models for the hybrid solar-geothermal system were developed using Aspen Plus and Aspen Dynamics. Turbine flexibility relative to vapor flow rate, temperature and pressure variations was analyzed. In one scenario, a parametric steady-state study was carried out to examine the performance over the range of conditions resulting from diurnal and seasonal variations. The results of the diurnal and seasonal parametric studies were grossly weighted to approximate a typical year in Nevada, and these results led to an estimate of the annualized electricity generation. In another scenario, a dynamic model was selected from possible "greenfield" hybrid systems and used to examine the transient performance for a typical January day and a typical July day in Nevada. The dynamic model approximates the thermal inertial of the heat exchangers and the working fluids in the exchangers, solar collectors, piping and storage tanks. The dynamic model is driven with forcing functions for solar input and ambient temperature to approximate the typical winter and summer days.
(cont.) In all cases, solar energy was found to come at a higher cost per kW capacity than geothermal when the cost of geothermal wells was not considered. However, including well costs had an effect of evening out the levelized cost of electricity. Model complexity increased as more solar heat was added to existing geothermal systems, which suggests that moving a higher exergy heat source down to a lower exergy heat source is difficult, especially given the transient nature of the solar resource. The models developed in this thesis demonstrate the design decisions and complex dynamic behavior inherent in this type of hybrid system.
by Andrew David Greenhut.
S.M.
Qiao, Huan. "Electrochemical Studies on Molten Fluoride Systems for Energy Conversion Related Applications." Kyoto University, 2003. http://hdl.handle.net/2433/148652.
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新制・課程博士
博士(エネルギー科学)
甲第10334号
エネ博第70号
新制||エネ||20(附属図書館)
UT51-2003-H755
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授 伊藤 靖彦, 教授 片桐 晃, 教授 尾形 幸生
学位規則第4条第1項該当
Choudhury, Fatema A. "Heteroatom doped porous carbon for alternative energy conversion and storage systems." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5588.
Full textIsopi, Jacopo <1990>. "Nanostructured Systems for Electrocatalysis of Reduction Reactions for Energy Conversion Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9771/1/Tesi%20PhD%20Isopi%20Jacopo%202021.pdf.
Full textJain, Chinmay. "Design, control and implementation of grid tied solar energy conversion systems." Thesis, IIT Delhi, 2017. http://localhost:8080/xmlui/handle/12345678/7058.
Full textLi, Wenyan Kusiak Andrew. "Predictive engineering in wind energy a data-mining approach /." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/399.
Full textHostettler, Jacob. "Advanced Control of Permanent Magnet Synchronous Generators for Variable Speed Wind Energy Conversion Systems." Thesis, Southern Illinois University at Edwardsville, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1588620.
Full textVarious environmental and economic factors have lead to increased global investment in alternative energy technologies such as solar and wind power. Although methodologies for synchronous generator control are well researched, wind turbines present control systems challenges not presented by traditional generation. The varying nature of wind makes achieving synchronism with the existing electrical power grid a greater challenge. Departing from early use of induction machines, permanent magnet synchronous generators have become the focus of power systems and control systems research into wind energy systems. This is due to their self excited nature, along with their high power density. The problem of grid synchronism is alleviated through the use of high performance power electronic converters. In achievement of the optimal levels of efficiency, advanced control systems techniques oer promise over more traditional approaches. Research into sliding mode control, and linear matrix inequalities with nite time boundedness and H∞ performance criteria, when applied to the dynamical models of the system, demonstrate the potential of these control methodologies as future avenues for achieving higher levels of performance and eciency in wind energy.
Diaz, Matias. "Control of the modular multilevel matrix converter for wind energy conversion systems." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/47157/.
Full textDíaz, Díaz Matías David. "Control of the modular multilevel Matrix converter for wind energy conversion systems." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/147484.
Full textLa potencia nominal de los Sistemas de Conversión de Energía Eólica se ha incrementado constantemente alcanzando niveles de potencia cercanos a los 10 MW. Por tanto, convertidores de potencia de media tensión están reemplazando a los convertidores Back-to-Back de baja tensión habitualmente empleados en la etapa de conversión de energía. Convertidores Modulares Multinivel se han posicionado como una solución atractiva para Sistemas de Conversión de Energía Eólica de alta potencia debido a sus buenas prestaciones. Algunas de estas prestaciones son la capacidad de alcanzar altos voltajes, modularidad y confiabilidad. En este contexto, esta tesis discute la aplicación del Convertidor Modular Matricial Multinivel para conectar Sistemas de Conversión de Energía Eólica de alta potencia. Los modelos matemáticos y estrategias de control requeridas para esta aplicación son descritos y discutidos en este documento. Las estrategias de control propuestas habilitan una operación desacoplada del convertidor, proporcionando seguimiento del máximo punto de potencia en el lado del generador eléctrico del sistema eólico, cumplimiento de normas de conexión en el lado de la red eléctrica y regulación de los condensadores flotantes del convertidor. La efectividad de las estrategias de control propuestas es validada a través de simulaciones y experimentos realizados con un prototipo de laboratorio. Las simulaciones se realizan con un Sistemas de Conversión de Energía Eólica de 10 MW operando a 6.6 kV. Dicho sistema se implementa en el software PLECS. Por otro, se ha desarrollado un prototipo de laboratorio de 6kVA durante el desarrollo de este proyecto. El prototipo de laboratorio considera un Convertidor Modular Matricial Multinivel de 27 módulos Puente-H . El sistema es controlado empleando una plataforma de control basada en una Digital Signal Processor conectada a tres tarjetas del tipo Field Programmable Gate Array que proveen de 50 mediciones análogo-digital y 108 señales de disparo. La entrada del convertidor es conectada a una fuente programable marca Ametek que emula el comportamiento de la turbina eólica. A su vez, la salida del convertidor es conectada a otra fuente programable con capacidad de producir fallas en la tensión. Los resultados obtenidos, tanto en el prototipo experimental como en simulación, confirman la operación exitosa del Convertidor Modular Matricial Multinivel en aplicaciones eólicas de alta potencia. En todos los casos, las estrategias de control propuestas aseguran regulación de la tensión en los condensadores flotantes, seguimiento del máximo punto de potencia en el lado del generador eléctrico del sistema eólico y cumplimiento de normas de conexión en el lado de la red eléctrica.
The nominal power of single Wind Energy Conversion Systems has been steadily growing, reaching power ratings close to 10MW. In the power conversion stage, medium-voltage power converters are replacing the conventional low-voltage back-to-back topology. Modular Multilevel Converters have appeared as a promising solution for Multi-MW WECSs due to their characteristics such as modularity, reliability and the capability to reach high nominal voltages. Thereby, this thesis discusses the application of the Modular Multilevel Matrix Converter (\mc) to drive Multi-MW Wind Energy Conversion Systems (WECSs). The modelling and control systems required for this application are extensively analysed and discussed in this document. The proposed control strategies enable decoupled operation of the converter, providing maximum power point tracking capability at the generator-side, grid-code compliance and Low Voltage Ride Through Control at the grid-side and good steady state and dynamic performance for balancing the capacitor voltages of the converter.\\ The effectiveness of the proposed control strategies is validated through simulations and experimental results. Simulation results are obtained with a 10MW, 6.6 kVM3C based WECS model developed in PLECS software. Additionally, a 5 kVA downscale prototype has been designed and constructed during this Ph.D. The downscale prototype is composed of 27 H-Bridges power cells. The system is controlled using a Digital Signal Processor connected to three Field Programmable Gate Array which are equipped with 50 analogue-digital channels and 108 gate drive signals. Two programmable AMETEK power supplies emulate the electrical grid and the generator. The wind turbine dynamics is programmed in the generator-side power supply to emulate a generator operating in variable speed/voltage mode. The output port of the M3C is connected to another power source which can generate programmable grid sag-swell conditions. Simulation and experimental results for variable-speed operation, grid-code compliance, and capacitor voltage regulation have confirmed the successful operation of the \mc{} based WECSs. In all the experiments, the proposed control systems ensure proper capacitor voltage balancing, keeping the flying capacitor voltages bounded and with low ripple. Additionally, the performance of the generator-side and grid-side control system have been validated for Maximum Power Point Tracking and Low-Voltage Ride Through, respectively.
Navaporn, Kaerkitcha. "Materials design and processing development of electrospun nanofibers for energy conversion systems." Kyoto University, 2018. http://hdl.handle.net/2433/232391.
Full textAugustine, Chad R. "Hydrothermal spallation drilling and advanced energy conversion technologies for Engineered Geothermal Systems." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51671.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
The purpose of this research was to study the various factors affecting the economic and technical feasibility of Engineered Geothermal Systems, with a special emphasis on advanced drilling technologies. The first part of the thesis was devoted to modeling and analysis of the technologies used to develop EGS projects. Since the cost of completing wells is a major factor in determining the economic feasibility of EGS projects, it is vital to be able to accurately predict in determining the economic feasibility of EGS projects, it is vital to be able to accurately predict their costs. Historic well cost data was analyzed to identify trends, and a drilling cost index for updating historic geothermal well costs to present day costs was developed. The effects of different advanced drilling technologies on drilling costs were estimated and incorporated into a techno-economic model to estimate their impact, as well as the impact of advanced reservoir stimulation technologies, on EGS levelized electricity costs. A technical analysis of geothermal binary Rankine cycle surface power plants was also performed to determine the effect of novel working fluids on plant efficiency for both sub- and supercritical binary cycles. The objective of the second part of the thesis was the application of thermal spallation drilling to deep boreholes. Thermal spallation is the fragmentation of a brittle solid into small, disc-like flakes by rapidly heating a confined fraction of the rock. It was proposed that the necessary temperatures and heat fluxes needed to induce thermal spallation in the high pressure, high density deep borehole environment could be achieved using hydrothermal flame technologies. An autoclave reaction system was designed and constructed to create flame jets in water at a pressure of 250 bar. The temperatures of these flames were measured, and attempts were made to use the flames to spall small rock samples. The experimental system was modified to study the centerline temperature decay of supercritical water jets injected at temperatures up to 525 °C into ambient temperature water. A device for measuring the heat flux from these jets was designed, constructed, and used to determine the heat transfer coefficients of the jets impinging against a flat surface. Together, these studies indicate that the necessary temperatures and heat fluxes required to induce thermal spallation in rocks can be achieved in a deep borehole.
by Chad R. Augustine.
Ph.D.
Riber, Marklund Anders. "Passive acoustic leak detection in energy conversion systems of sodium fast reactors." Doctoral thesis, KTH, Reaktorteknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199415.
Full textQC 20170109
Muhammad, Musbahu. "High gain non-isolated DC-DC converter topologies for energy conversion systems." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3665.
Full textXu, Jing. "FUNDAMENTAL STUDIES OF ELECTROCATALYTIC SYSTEMS WITH RELEVANCE TO ENERGY CONVERSION AND STORAGE." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1449139728.
Full textPopli, Nipun. "Multi-layered Energy Conversion and Frequency Control in Complex Electric Power Systems." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/916.
Full textAl-Qrimli, Fadhil Abbas Mehdi. "An energy conversion scheme using a permanent magnet generator and a PWM, GTO converter." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304736.
Full textFreas, Rosemarv M. "Analysis of required supporting systems for the Supercritical CO2 power conversion system." Thesis, Cambridge Massachusetts Institute of Technology, 2007. http://hdl.handle.net/10945/2992.
Full textContract number: N62271-97-G-0026.
US Navy (USN) author
Ochsmann, Julian Robert [Verfasser]. "Excited-state dynamics in donor-acceptor systems for energy conversion / Julian Robert Ochsmann." Mainz : Universitätsbibliothek Mainz, 2015. http://d-nb.info/1079623396/34.
Full textKarakus, Uzuner Melike [Verfasser]. "Charge carrier dynamics in hybrid systems for solar energy conversion / Melike Karakus Uzuner." Mainz : Universitätsbibliothek Mainz, 2017. http://d-nb.info/1132608430/34.
Full textSchutte, Adriaan Nicholaas. "A bi-directional, direct conversion converter for use in household renewable energy systems." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1726.
Full textA bi-directional, direct conversion switch-mode converter is proposed for use in distributed household renewable energy systems. The converter is intended as the central interface between the household energy system’s low voltage Direct Current bus and the high voltage Alternating Current bus. The low voltage DC bus is connected to renewable generation and storage devices, while the high voltage AC bus is connected to the user’s equipment and the mains grid. The converter overcomes the inherent reverse-duty cycle problem associated with bi-directional converters by using a combination step-up / step-down half-bridge converter on the high voltage side of a high frequency transformer. The low voltage side of the transformer is driven by a full bridge inverter that acts as a rectifier during reverse mode. In order to control the flow of power in both directions the converter implements Average Current Mode Control. A method is developed to determine the transfer functions of common switch-mode converters by inspection alone. This method is applied to the proposed converter, and both current and voltage mode control loops are designed with the frequency response method. The control system is implemented using a Digital Signal Processor. A method of simultaneously simulating both the converter hardware and software is developed using VHDL. This method greatly reduced the development effort of the converter. The operation of the proposed converter is verified through this method of simulation. A prototype converter is constructed and successfully tested, thereby proving the viability of the proposed converter topology and control methodology.
Vidakovič-Koch, Tanja Verfasser], and Kai [Gutachter] [Sundmacher. "Bioelectrochemical systems for energy and materials conversion / Tanja Vidakovič-Koch ; Gutachter: Kai Sundmacher." Magdeburg : Universitätsbibliothek Otto-von-Guericke-Universität, 2019. http://d-nb.info/1219965375/34.
Full textMatas, Adams Alba Maria. "Semiconductor Nanoparticles as Platform for Bio-Applications and Energy Related Systems." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/334391.
Full textEsta tesis esta dedicada a la sintesis, caracterizacion y aplicaciones de diferentes nanomateriales que presentan la propiedad de ser semiconductores. Esta dividida en tres bloques, en los cuales, en el primer de ellos se habla sobre quantum dots (QDs), que son nanoparticulas fluorescentes cuya longitud de onda de emision varia con el tamaño. Dichos materiales se estan usando ultimamente como sustitutos de los colorantes organicos ya que presentan ventajas, la principal es que no pierden su emision con el tiempo. Estos QDs han sido usados para estudiar su interaccion con el oro (que aumenta su intensidad de fluorescencia), han sido encapsulados usando polimeros para usarlos como controles en citometria de flujo y por silica para usarlos (una vez unidos a un peptido y un colorante organico adecuado) como detectores de fibrosis quistica. Finalmente tambien han sido usados en esta tesis para intentar seguir el movimiento de un receptor en plaquetas. En el segundo bloque de la tesis se habla de up conversion nanoparticles, cuya diferencia frente a los QDs es que se excitan a mayor longitud de onda a la que emiten, por lo que son capaces de absorber en el infrarojo y emitir en el visible, haciendolos ideales para aplicaciones en biologia. En esta tesis se usaron para reconocer un receptor en neutrofilos y para introducirlo dentro de hidrotalcitas (material que no es reconocido por el cuerpo como extraño) para asi poder liberarlo en el organismo. Finalmente, en el tercer bloque se han sintetizado materiales para catalisis (sulfuro de bismuto) y para celdas solares (oxido de titanio).
This thesis is dedicated to the synthesis, characterization and application of different nanomaterials that are semiconductors. It is divided in three blocks, in the first one we talk about quantum dots (QDs), that are fluorescent nanoparticles whose wavelength of emission changes with size. Such materials are being used as substitutes of organic dyes, due to the many advantages they present, the main one is that the fluorescence is not lost with time. These QDs have been used to study their interaction with gold ( that increases the fluorescence intensity), they have been encapsulated with polimers to be used as controls in flow cytometry or by silica to use them as sensors for cystic fibrosis (once they have been attatched to the right polymer and dye). Finally, in this thesis, they have been also used to track the movement of a platelet receptor. In the second block we talk about up conversion nanoparticles, which only difference regarding QDs is that they are excited using a longer wavelength than the emission, so they are able to absorb in the infrared and emit in the visible range of light, making them ideal for biological applications. We have use this materials to recognice an specific receptor in neutrophils as well as to be surrounded by hydrotalcite (body friendly material) so it can be released in the organism. Finally, in the third block we have syntesized materials for catalysis (bismuth sulfide) and for solar cells (titanium oxide for perovskite solar cells).
Motjolopane, Bokang Patrick. "A power harvesting technique to facilitate energy conversion in distributed wireless sensor networks." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/1113.
Full textDistributed wireless sensor networks (DWSNs) are applied in a variety of applications that can enhance the quality of human life or even save lives, such as in fire monitoring, where DWSN microsensors relay the exact location of the fire to water sprinkler actors to automatically extinguish the fire. Batteries are currently the predominant source of energy in DWSNs. one of the key obstacles in the adoption of DWSN technology is the limited lifetime of batteries in microsensors. Recharging or replacing depleted batteries can significantly increase costs in DWSNs. The aim of this study is to address the power challenge in DWSNs by proposing a sixteen-element equiangular spiral rectenna to ahrvest ambient microwave energy to supply indoor DWSNs. The study concludes that this rectenna model has the potential to generate power that enables long periods of operation of the DWSNs without human intervention in the power manageement process, thus reducing maintenance and administration costs. The efficiency of the rectenna model was tested in an anechoic chamber. Efficiency test results indicated that the highest efficiency of 2% for the rectenna model was achieved as 2 GHz for an ambient power of -6 dBm across a 1 K ohm load resistence. The study further concludes that the current rectenna model size of sixteen elements is a limiting factor for the deployment of DWSNs.
Chahwan, John A. "Vanadium-redox flow and lithium-ion battery modelling and performance in wind energy applications." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100223.
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