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Shoai, Tehrani Bianka. "Electricity investments and development of power generation capacities : An approach of the drivers for investment choices in Europe regarding nuclear energy." Phd thesis, Ecole Centrale Paris, 2014. http://tel.archives-ouvertes.fr/tel-01020273.
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In a context of growing energy prices and climate change mitigation, the thesis addresses the issues of investments in power generation capacities and in particular nuclear capacities. Given that the Generation IV of nuclear reactors is supposed to be ready in 2040 for industrial deployment, the purpose of the thesis is to study the conditions for electricity investments in France and Europe within this horizon, in order to assess development perspectives for nuclear energy and for potential emergence of Generation IV on the European market. To do so, it is necessary to study the mechanisms at stake in investment choices taking into account all power generating technologies. Economic theory usually bases the choice on long-term economic rationality, which does not allow explain the actual choices observed in European electricity mix. The objective of the research work is thus to identify investment choice drivers and to propose an approach describing the behavior of investors in a more realistic way. A multidisciplinary approach was adopted to explore the question. It combines a historical analysis of drivers evolution according to historical context, a structural analysis of these drivers to identify favorable scenarios for future nuclear reactors, a value creation approach to replicate investors' preferences in those scenarios, and last, a value option approach focusing on nuclear technologies and comparing competitiveness of Generation IV reactors with current reactors. As a result, only strong climate policy combined to government support to nuclear energy could allow industrial development of Generation IV, while high progress of renewables does not lessen the attractiveness of nuclear energy.On a international level, such analysis could be broaden by taking into account the drivers specific to each area of the world, such as highly growing demand in developing countries.
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Paul, Sushanta. "Optimal capacitor placement for line-loss reduction and importance of voltage reduction during reactive power compensation and its effects on load, line loss, and generation." Diss., Wichita State University, 2013. http://hdl.handle.net/10057/10615.
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A methodology to determine the optimal capacitor locations and sizes to minimize line loss on a radial distribution system was developed in this work. Both the power loss index (PLI)-based approach and the loss sensitivity coefficient-based approach were comparatively studied to determine the optimal capacitor location. The index-based approach combined with a genetic algorithm was used to determine the capacitor sizes. After reactive power compensation voltage-dependent loads consume more power because of the increase in node voltage; therefore, customers pay more for their electricity while utilities experience savings from line-loss reduction. Therefore, a rationale for the necessity of reducing voltage for load demand reduction during reactive power compensation is presented, and the optimal voltage setting at the substation regulator is determined. The joint effect of ambient temperature, price, size, and phase kVAr of the capacitor on load, line loss, and generation is analyzed using a 24 factorial design. How consumer energy consumption, line loss, and generation are affected by voltage reduction is also evaluated. Since bus voltage also depends on line resistance, which varies with ambient temperature, the impact of temperature on power consumption, line loss, and generation is discussed as well. At reduced voltage, variations in line loss need to be analyzed, because losses affect the cost-benefit analysis. A model is derived that explains, at reduced voltage, how line loss varies with the type of load. Also analyzed is the effect of line resistance on line loss for various types of loads. The results of this work will improve the effectiveness and reliability of future voltage-reduction programs. Finally, analyses for negative line loss, higher voltage at the downstream node, and the active and reactive current components of a capacitor are presented in this work.<br>Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science
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Michel, André Bernardes. "Alocação de bancos de capacitores e reguladores de tensão usando otimização por metas considerando geração distribuída." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/118829.
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Sistemas de Distribuição de Energia Elétrica (SDEE) estão, pelas próprias condições de funcionamento, sujeitos a perdas de energia e quedas nos níveis de tensão. Uma das formas de reduzir as perdas e ao mesmo tempo melhorar o perfil de tensão do SDEE consiste na utilização de bancos de capacitores e reguladores de tensão ao longo dos alimentadores. Para isto a alocação ótima destes equipamentos torna-se de fundamental importância, logo este trabalho tem por objetivo a utilização de um método quadrático de programação por metas multiobjetivo para a ótima alocação desses equipamentos visando a redução de perdas (meta 1) com o menor custo de investimento (meta 2) sujeito a restrições do fluxo de potência, limites técnicos de operação, mudança no controle dos capacitores chaveados e dos taps dos reguladores de tensão. O constante aumento na penetração da geração distribuída traz novos desafios para o controle e a operação dos SDEE. A metodologia proposta considera os efeitos destas fontes de geração e os seus impactos na alocações ótima dos bancos de capacitores e reguladores de tensão. Com o intuito de resolver o problema de otimização em programas comerciais como Gurobi e Cplex uma metodologia linear de cálculo de fluxo de potência é utilizada. Os algoritmos foram desenvolvidos no software Matlab, e posteriormente foi realizada a conversão para linguagem GAMS (Generic Algebraic Modeling System) para utilização dos solvers na plataforma NEOS (Network Enabled Optimization System).<br>Power distribution systems (DS) are susceptible to energy loss and voltage drops, mainly because of the way that they are operated and built. One way to minimize system loss and improve the voltage profile of DS is with the use of capacitor banks and voltage regulators (VRs) along the distribution feeders. In this scenario, the optimal placement of these devices becomes crucial. In this paper, a quadratic multi objective goal programming method is proposed to obtain the optimal placement of these devices, where the goals are energy loss (goal 1) and the total investment cost (goal 2). The model is subject to system operation constraints, such as power flow demands, limits of voltages and currents, number of stages of switched capacitors and the tap control of VRs. The increase of distributed generation penetration brings new challenges for control and operation of DS. The proposed methodology considers the effects of these power sources and their impact on optimal allocations of capacitors and VRs. With the aim of solving the optimization problem in commercial programs, a linear power flow is used. The algorithms were developed with Matlab software and the conversion was made to a General Algebraic Modeling System (GAMS) language and solved in the NEOS (Network Enabled Optimization System) platform.
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Kim, Jong Wan. "Back to Back Active Power Filter for Multi-Generator Power Architecture with Reduced dc-link Capacitor." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96638.
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Multi-pulse converters have been widely used for a multi-megawatt scale power generating system to comply with harmonic regulations. Among all types of multi-pulse converters, a 12-pulse converter is the most widely used due to the simple structure, which consists of a delta-delta and a delta-wye phase-shift transformer pair and it effectively mitigates undesirable harmonics from the nonlinear load.
In the early 2000s, a shunt type passive front-end for a shipboard power system was proposed. By shunting the two gensets with 30° phase angle difference, a single phase-shift transformer effectively eliminates 5th and 7th harmonics. It achieves a significant size and weight reduction compared to a 12-pulse converter while keep the comparable harmonic cancellation performance. Recently, a hybrid type front-end was proposed. On top of the passive front-end, 3 phase active power filter was added and an additional harmonic cancellation was achieved to further eliminate 11th and 13th harmonics. However, the performance of both the passive and hybrid type front-end are highly dependent on the size of the line reactor in ac mains.
A back to back active power filter is proposed in this dissertation to replace the phase-shift transformer in the multi-generator power architecture. The proposed front-end does not include phase-shift transformer and the size and the weight of the overall front-end can be significantly reduced. Due to the active harmonic compensation, the back to back front-end achieves better power quality and the line reactor dependency is improved. The number of required dc-link capacitors is reduced by half by introducing a back to back configuration and the capacitor size is reduced by adjusting the phase angle difference of genset to cancel out the most significant voltage harmonics in the shared dc-link bus.
The overview of the existing shunt type front-end is provided and the concept of back to back active power filter is validated by simulation and prototype hardware. The comparison between existing front-end and the proposed front-end is provided to highlight the superior performance of back to back active front-end. The dc-link bus current and voltage ripple analysis is provided to explain the dc-link ripple reduction mechanism.<br>Doctor of Philosophy<br>The transportation electrification has gained more and more attention due to its smaller carbon dioxide emission, better fuel efficiency. The recent advances in power devices, microcontrollers, and transducers accelerate the electrification of transportation. This trend is shown in the propulsion system in marine transport as well and the electric propulsion system has been widely used to meet the strict environmental regulations.
However, the non-linear circuit components such as capacitor and diode in the electric propulsion system draw non-linear current and significantly deteriorate power quality and lead to critical problems such as reduced life span of circuit components Accordingly, a front-end is required to improve power quality. Also, it is desired to have compact and lightweight front-end for installation flexibility and fuel efficiency improvement.
In this dissertation, several front-ends using a phase-shift transformer are reviewed and a detailed analysis is provided to help understand the harmonic cancellation principle of the existing front-end through equivalent circuit analysis, quantitative analysis, and a phasor diagram representation. Based on the analysis of the existing front-ends and shipboard power architecture, lightweight and high-performance front-end is proposed and verified by simulation and prototype hardware.
The performance, size comparison between existing front-end and the proposed front-end is provided to show the advantage of the proposed front-end.
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Enge, Thomas. "Power generation assets." Doctoral thesis, Humboldt-Universität zu Berlin, Wirtschaftswissenschaftliche Fakultät, 2010. http://dx.doi.org/10.18452/16223.
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Wir betrachten die Einsatzplanung (Unit Commitment Problem) für ein thermisches Kraftwerk mit zusätzlicher Energienebenbedingung. Dazu definieren wir ein stochastisches dynamisches Programm (SDP)mit stetigem Zustandsraum und integriertem gemischt-ganzzahligem Programm (MIP). Wir stellen einen effizienten Algorithmus vor zur Lösung des MIP über eine Matrixmultiplikation und verwenden eine Hauptkomponentenanalyse zur Reduzierung der Dimension des Preisvektors. Außerdem liefern wir zum Vergleich des SDP eine vereinfachte Regel zur Energieallokation. Zur Beurteilung der Güte der Ergbnisse betrachten wir als nächstes obere Grenzen. Für eine vereinfachte Modellierung des Kraftwerks als Swing Option mit Mehrfachausübung auf derselben Stufe bestimmen wir formal eine solche obere Grenze. Abschließend untersuchen wir Strategien zur Vermeidung des Spotpreisrisikos, dem das Kraftwerk aufgrund der Nichtspeicherbarkeit von Strom besonders ausgesetzt ist. Zunächst konzentrieren wir uns auf die Messung des Spotpreisrisikos und stellen drei neue Maße vor (Forward Delta, Synthetisches Spot Delta und Earnings-at-Risk). Danach präsentieren wir Strategien zur Risikoreduzierung vor und während der Lieferperiode. Im zweiten Fall wird versucht, durch einen neuen Produktionsplan das Risiko mehr als den Gewinn zu senken. Wir schlagen dazu einen Referenzwert vor, den wir EaR-effizienten Optionswert nennen und in eine neue Erzeugungspolitik basierend auf Quantil-Regression einfließt. Die Politik beschreibt ein Preisband innerhalb dessen ein beobachteter Preis zur Ausübung eines Swing-Rechts führt. Für den Fall der amerikanischen Option können wir EaR-Effizienz mit dieser Strategie nachweisen. Abschließend betrachten wir die Absicherung des Kraftwerks vor der Lieferung durch gezielten Verkauf einer Swing Option. Wir stellen eine Heuristik basierend auf unserem synthetischen Spot Delta vor, um Swinghöhe und –anzahl effizient zu finden.<br>We define a new not yet investigated unit commitment problem that introduces an energy constraint to a thermal power plant. We define a stochastic dynamic program with continuous state space and nested mixed integer program (MIP). We introduce a fast implementation approach by replacing the MIP with an efficient matrix calculation and use principal component analysis to reduce the dimension of the price vector. We also provide a fast heuristic valuation approach for comparison. We investigate the theory of upper bounds for a proper validation of our power plant results. In particular we provide an extension for swing options with multiple exercises at the same stage. Finally we provide a risk analysis for our thermal power plant. In particular we investigate strategies to reduce the spot price risk to which power plants are significantly exposed. First, we focus on the measurement of spot price risk and propose three appropriate risk figures (Forward delta, synthetic spot delta and Earnings-at-Risk ). Second we suggest risk mitigation strategies for both periods, before and in delivery. The latter tries to alter the dispatch policy i.e. pick less risky hours and accept a (desirably only slightly) smaller return. We introduce a benchmark that we will call EaR-efficient option value. We propose a mitigation strategy for this benchmark that is based on quantile regression. It defines a price interval for executing an individual swing right and is therefore very well suited for real world applications. In case of an American option we are able to show EaR-efficiency of our strategy. Finally, we investigate hedging strategies before delivery. In particular, we look at a hedge for the spot price risk of the power plant using a swing option. We propose a heuristic based on our synthetic spot deltas to find the swing number and size of the swing option for a given upper generation amount.
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Navarrete, Pablo-Romero Javier. "Power Quality for Distributed Wind Power Generation." Thesis, KTH, Elektroteknisk teori och konstruktion, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105221.
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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.<br>StandUp
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Ali, Richard A. "Reliability and characterization of high voltage power capacitors." Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/41346.
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Approved for public release; distribution is unlimited.<br>Alternative energy products are an increasingly common sight on military bases in the United States. Energy product reliability affects the sustainability and cost-effectiveness of these systems, which must be tested by outside entities to ensure quality. The purpose of this thesis is to perform component level reliability testing on a high voltage power capacitor used in an electrical vehicle solar charging system. A component level characterization was performed to better understand the physical attributes of these capacitors. This investigation identified the expected component lifetime and conditions in which this component will become less reliable. Results are compared to those published by the manufacturer.
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Montenegro, León Alejandro. "Advanced power electronic for wind-power generation buffering." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010112.
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Al-Anfaji, Ahmed Suaal Bashar. "The optimization of combined power-power generation cycles." Thesis, University of Hertfordshire, 2015. http://hdl.handle.net/2299/15485.
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An investigation into the performance of several combined gas-steam power generating plants’ cycles was undertaken at the School of Engineering and Technology at the University of Hertfordshire and it is predominantly analytical in nature. The investigation covered in principle the aspect of the fundamentals and the performance parameters of the following cycles: gas turbine, steam turbine, ammonia-water, partial oxidation and the absorption chiller. Complete thermal analysis of the individual cycles was undertaken initially. Subsequently, these were linked to generate a comprehensive computer model which was employed to predict the performance and characteristics of the optimized combination. The developed model was run using various input parameters to test the performance of the cycle’s combination with respect to the combined cycle’s efficiency, power output, specific fuel consumption and the temperature of the stack gases. In addition, the impact of the optimized cycles on the generation of CO2 and NOX was also investigated. This research goes over the thermal power stations of which most of the world electrical energy is currently generated by. Through which, to meet the increase in the electricity consumption and the environmental pollution associated with its production as well as the limitation of the natural hydrocarbon resources necessitated. By making use of the progressive increase of high temperature gases in recent decades, the advent of high temperature material and the use of large compression ratios and generating electricity from high temperature of gas turbine discharge, which is otherwise lost to the environment, a better electrical power is generated by such plant, which depends on a variety of influencing factors. This thesis deals with an investigation undertaken to optimize the performance of the combined Brayton-Rankine power cycles' performance. This work includes a comprehensive review of the previous work reported in the literature on the combined cycles is presented. An evaluation of the performance of combined cycle power plant and its enhancements is detailed to provide: A full understanding of the operational behaviour of the combined power plants, and demonstration of the relevance between power generations and environmental impact. A basic analytical model was constructed for the combined gas (Brayton) and the steam (Rankine) and used in a parametric study to reveal the optimization parameters, and its results were discussed. The role of the parameters of each cycle on the overall performance of the combined power cycle is revealed by assessing the effect of the operating parameters in each individual cycle on the performance of the CCPP. P impacts on the environment were assessed through changes in the fuel consumption and the temperature of stack gases. A comprehensive and detailed analytical model was created for the operation of hypothetical combined cycle power and power plant. Details of the operation of each component in the cycle was modelled and integrated in the overall all combined cycle/plant operation. The cycle/plant simulation and matching as well as the modelling results and their analysis were presented. Two advanced configurations of gas turbine cycle for the combined cycle power plants are selected, investigated, modelled and optimized as a part of combined cycle power plant. Both configurations work on fuel rich combustion, therefore, the combustor model for rich fuel atmosphere was established. Additionally, models were created for the other components of the turbine which work on the same gases. Another model was created for the components of two configurations of ammonia water mixture (kalina) cycle. As integrated to the combined cycle power plant, the optimization strategy considered for these configurations is for them to be powered by the exhaust gases from either the gas turbine or the gases leaving the Rankine boiler (HRSG). This included ChGT regarding its performance and its environmental characteristics. The previously considered combined configuration is integrated by as single and double effect configurations of an ammonia water absorption cooling system (AWACS) for compressor inlet air cooling. Both were investigated and designed for optimizing the triple combination power cycle described above. During this research, tens of functions were constructed using VBA to look up tables linked to either estimating fluids' thermodynamic properties, or to determine a number of parameters regarding the performance of several components. New and very interesting results were obtained, which show the impact of the input parameters of the individual cycles on the performance parameters of a certain combined plant’s cycle. The optimized parameters are of a great practical influence on the application and running condition of the real combined plants. Such influence manifested itself in higher rate of heat recovery, higher combined plant thermal efficiency from those of the individual plants, less harmful emission, better fuel economy and higher power output. Lastly, it could be claimed that various concluding remarks drawn from the current study could help to improve the understanding of the behaviour of the combined cycle and help power plant designers to reduce the time, effort and cost of prototyping.
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SOARES, LEONARDO BRAGA. "POWER GENERATION INVESTMENTS SELECTION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11951@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>A reestruturação do setor de energia elétrica, iniciada nos
anos 90, teve como uma de suas principais implicações a
introdução da competição na atividade de geração. A expansão
do parque gerador, necessária para garantir o equilíbrio
estrutural entre oferta e demanda, é estimulada por
contratos de longo prazo negociados em leilões, na
modalidade de menor tarifa. Destarte, o investidor deve
oferecer um limite de preço para que o seu projeto seja
competitivo (de forma a ganhar a licitação), mas que ao
mesmo tempo seja suficiente para remunerar seu investimento,
custos de operação e, sobretudo, protegê-lo contra todos os
riscos intrínsecos ao projeto. Nesse contexto, as duas
principais contribuições do presente trabalho são: (i) a
proposição de uma metodologia de precificação de riscos,
utilizando o critério do Value at Risk (VaR), que indica a
máxima perda admitida pelo invetidor avesso a risco, com um
determinado nível de confiança, e (ii) a aplicação de
diferentes modelos de seleção de carteiras, que incorporam o
critério do VaR para otimizar um portfolio com diferentes
tecnologias de geração de energia. Os resultados da
precificação de riscos são úteis para determinar os
componentes críticos do projeto e calcular a
competitividade (preço) de cada tecnologia. A aplicação de
diferentes métodos de seleção de carteiras busca determinar
o modelo mais indicado para o perfil das distribuições de
retorno dos projetos de geração, que apresentam assimetria e
curtose elevada (caldas pesadas).<br>The new structure of the brazilian electric sector,
consolidated by the end of the 90s main
implication the introduction of competition in the power
generation activity. The expansion of generation capacity,
responsible to ensure structural equilibrium between supply
and demand, is stimulated by long-term contracts negotiated
through energy auctions. Therefore, the investor must give a
competitive price (in order to win the auction), but also
sufficient to pay his investment, operational costs and,
especially, protect him against all project risks.
In this role, the two main contributions of this work are:
(i) to suggest a methodology of risk pricing, using the
Value at Risk (VaR) criterium, which gives the maximum loss
admitted by the risk averse investor, with a specified
confidence level, and (ii) to apply different portfolio
selection models, which incorporates the VaR criterium to
optimize a portfolio with different power generation
technologies. The risk pricing results are usefull to
determine the project critical components and to calculate
the competitiviness (price) of each technology. The study of
different portfolio selection methods aims to investigate
the most suitable model for the return distribution shape,
characterized by having assimetry and curtosis (heavy tails).
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Fucetola, Jay J. "Mesofluidic magnetohydrodynamic power generation." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74463.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 161-162).<br>Much of the previous research into magnetohydrodynamics has involved large-scale systems. This thesis explores the miniaturization and use of devices to convert the power dissipated within an expanding gas flow into electricity. Specific properties, such as high surface tension, allow for unique possibilities in the design of such devices. The material covered includes a brief derivation of the theory describing steady well-developed MHD flows within circular and rectangular channels. Numerical simulations are used to elucidate the relationships derived theoretically and to enable future design without the reliance upon such simulation. Fabricated devices are experimentally observed to determine the agreement with the modeled behavior. Finally, a design is proposed that is predicted to be a viable generator as well as a means for further examining the unanswered questions raised by the research performed in this thesis.<br>by Jay J. Fucetola.<br>S.M.
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Chou, Paul L. (Paul Lee). "Low power ROM generation." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40995.
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Anderson, Guy Stewart. "Managing nuclear power generation." Thesis, University of Manchester, 2004. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.647092.
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Imam, Afroz M. "Condition Monitoring of Electrolytic Capacitors for Power Electronics Applications." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14472.
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The objective of this research is to advance the field of condition monitoring of electrolytic capacitors used in power electronics circuits.
The construction process of an electrolytic capacitor is presented. Descriptions of various kinds of faults that can occur in an electrolytic capacitor are discussed. The methods available to detect electrolytic capacitor faults are discussed. The effects of the capacitor faults on the capacitor voltage and current waveforms are investigated through experiments. It is also experimentally demonstrated that faults in the capacitor can be detected by monitoring the capacitor voltage and current.
Various ESR estimation based detection techniques available to detect capacitor failures in power electronics circuits are reviewed. Three algorithms are proposed to track and detect capacitor failures: an FFT based algorithm, a system modeling based detection scheme, and finally a parameter estimation based algorithm. The parameter estimation based algorithm is a low-cost real-time scheme, and it is inexpensive to implement.
Finally, a detailed study is carried out to understand the failure mechanism of an electrolytic capacitor due to inrush current.
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Zubieta, Bernal Luis Eduardo. "Characterization of double-layer capacitors for power electronics applications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28861.pdf.
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Rennie, Anthony. "Nitrogen-enriched carbon materials for high-power electrochemical capacitors." Thesis, University of Strathclyde, 2011. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=16769.
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Wade, Timothy Lawrence. "High power carbon based supercapacitors /." Connect to thesis, 2006. http://repository.unimelb.edu.au/10187/439.
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Energy storage devices are generally evaluated on two main requirements; power and energy. In supercapacitors these two performance criteria are altered by the capacitance, resistance and voltage. (For complete abstract open document)
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Rosas, Espejel Juventino Delfino. "RF to DC power generation." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/176.
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Thesis (M.S.) -- University of Maryland, College Park, 2003.<br>Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Wallace, Alexander Robert Swan. "Small-scale hydro power generation." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/14633.
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The requirement for decentralised power generation in the rural electrification of developing countries is vast, and extensive hydrological resources for small-hydro power have been identified. Despite this, the utilisation of small-scale hydro is extremely slow, and the market is not fully developed. This study reviews the marketplace for small-scale hydro in the industrialised, newly-industrialised, less-developed and third-world countries. The extent, characteristics, and timescales of small-hydro development are used to estimate the market for varying levels of power generation technology. Existing power plant and practices as applied to rural electrification programmes are examined and suggestions are made to improve the cost effectiveness of the generating plant. The economic effects which increase the cost of energy produced at smaller sites are considered and a pre-feasibility cost model is proposed. Existing design methods for Pelton turbines are appraised. A new method of designing and estimating the performamce of multi-jet machines has been developed in a comprehensive software package, which is described and evaluated. A test facility designed and constructed during the study is described, and the results obtained by testing a small Pelton turbine are presented. Conclusions are drawn at the end of each chapter and these are ultimately summarised in an overview of the effective market and the means by which Pelton turbine technology may be applied more widely. The market sectors which will benefit by the availability of the design software are identified, together with further work required to integrate the design ability into manufacture.
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Greenhalgh, Daniel. "Aerostat for electric power generation." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415870/.
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Solar power is one source of renewable energy that is well established but, in the UK, expensive per kilowatt due to low levels of insolation caused by cloud cover. To over- come the limitations of cloud cover, an aerostat for electrical power generation has been proposed in literature. The aerostat would float at an altitude of six kilometres, above the majority of cloud cover, and can receive around 3.3 times the annual insolation of a ground based system in the UK. The aim of this work is to further demonstrate the feasibility of such an aerostat concept. This is achieved by considering three areas of study: the solar array shape, the control system and the thermal analysis. The analysis of the solar array compares two configurations, a spherical cap and a stepped array, in terms of size, mass, power production and sensitivity to pointing error. The results show that a spherical cap array has a lower sensitivity to pointing error and, with the support structure required for a stepped array, a lower mass despite its larger surface area. The control system design takes a proposed system concept as its starting point and revises it. The system is sized and its Sun tracking and disturbance rejection performance is simulated. It is found that the system is capable of maintaining a pointing error of within 1.81◦ during tracking and of correcting disturbances. The thermal analysis extends previous models to include the effects of a ballonet used for gas pressure regulation. The model is validated against experimental data and shows a good agreement (r ≥ 0.9). The model is then applied to the aerostat concept and shows that the gas pressure can be maintained within acceptable bounds and that the solar array does not become hot due to solar heating. Overall, the results of this study increase confidence in the feasibility of the aerostat concept.
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Redi, Stefano. "Aerostat for electric power generation." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/390101/.
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The exploitation of renewable energy sources is currently at the top of the agenda of many governments that are required to face the problem of the rising energy demand. In particular photovoltaics is considered one of the most promising technologies to meet the energy needs in the long term. However the effective exploitation of this source has always been hindered in many northern countries (like the UK) due to the weather conditions which are detrimental for the efficiency of photovoltaic generators. As a possible solution to this problem, this research presents the preliminary concept evaluation of an innovative power generator based on photovoltaic and lighter than air technologies (Aerostat for Electric Power Generation – AEPG). The generator consists of a helium filled platform tethered to the ground that would be used to locate a photovoltaic array at high altitude, ideally above the cloud coverage, in order to reduce the negative effect of the atmosphere and optimize the power production. The power produced at high altitude would then be transmitted to the ground via the mooring tether. First of all, the potential of this technology is evaluated in terms of the solar energy that can be collected at high altitude. The results obtained demonstrate that a generator located at an altitude between 6 km and 12 km could collect between 3.3 and 4.9 times the solar radiation that would fall on a ground based photovoltaic array. Furthermore the environmental conditions in which the system is due to operate are evaluated, employing standard atmospheric models and experimental wind speed datasets. An overview of the main parameters involved in the design is then provided and general considerations are discussed in order to narrow the range of values these different parameters can take. A simplified mathematical model is introduced to assess the performance of the system in steady state conditions and a set of design parameters is chosen to define a baseline configuration for the concept design. Moreover, a transient 3D analysis of the whole system is performed in order to check if the dynamic behaviour can constitute a show stopper. Finally the concept design of the AEPG is addressed and the most critical technical issues are identified. The location of the different subsystems is briefly discussed and a possible solution for the system layout is proposed. The study is completed with an initial sizing of the main components (structural in particular) in order to evaluate the different mass contributions and provide a preliminary assessment of the technical feasibility of the AEPG.
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CARRARA, Samuel. "Small-scale biomass power generation." Doctoral thesis, Università degli studi di Bergamo, 2010. http://hdl.handle.net/10446/595.
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In recent years considerable attention has been paid to power generation from biomass, especially in small scale plants. Several plant configurations have been proposed and investigated, but so far, definitely preferable technological solutions have not been found yet. Moreover, a comparison of their performances is often difficult, due to the fact that working assumptions are not always consistent.
The aim of the present work is to provide a full overview on small scale technologies regarding biomass exploitation (particularly woody one) for power generation, in order to define the most interesting solutions from a thermodynamic and economic point of view. Existing configurations or those which are expected to be potentially available on the market in the near future have been considered. Three plant sizes have been focused: 100 kWel, 1 MWel and 5 MWel. Internal combustion engines (ICE), (micro) gas turbines (mGT/GT), both internally and externally fired, and organic Rankine cycles (ORC)
have been taken into account as power plants, while direct combustion and gasification have been considered for biomass. Simulations show that the externally fired gas turbine is the most promising technology at small scale (100 kWel), if a high temperature heat exchanger is available. A gasifier coupled with an internal combustion engine is instead preferable at larger scales (1 MWel and 5 MWel).
An also proposed sensitivity analysis concerning moisture effects shows that biomass drying with flue gas is generally disadvantageous, even if sometimes (e.g. in gasifiers) necessary, because of the dryer cost.
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Brown, Robert Winston, and rwb@rmit edu au. "Electrical and Thermal Modelling of Low Power Metallised Polypropylene Capacitors." RMIT University. Electrical and Computer Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080130.155318.
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Metallised polypropylene (MPP) capacitors, the dominant capacitor type used in a wide range of power and electronic circuit applications, offer high volumetric capacitor density, low cost, excellent frequency characteristics and a unique ability to recover from point failures in the dielectric film. However MPP capacitors have a generic weakness that is not well understood, failure of the self-healing process leading to ongoing catastrophic failure. The work described in this thesis includes the derivation of an improved electrical model of a capacitor and the uncovering of a mechanism for the catastrophic failure mode. Corrosion of the thin metallic field is firmly linked to drastic increases in metal film current densities and generation of hot spots in capacitors. In the work, novel formulae were derived relating capacitor parameters such as equivalent series resistance and equivalent series capacitance to frequency and physical characteristics such as metal film resistivity and physical dimensions of multiple layer capacitors. Modelling using numerical methods and diffusion equation showed that capacitors with double-end connection topology have more uniform voltage and power distribution than single-end connected capacitors. External characteristics of both connection topologies were shown to be virtually identical up to frequencies well above typical self-resonance. The aggregate spatial distribution of power from both layers and the voltage across the dielectric were found to be fundamentally different in the two circuit connection topologies. In this work it was shown that above singularity frequencies defined by distributed capacitance and metal film spreading resistance, equivalent series resistance and capacitance both fall with the square root of frequency Analysis of the inductance of typical MPP capacitors for single-end and double-end connected topologies and for circumferentially connected capacitor metallization showed that the magnitude and effect of distributed inductance in typical MPP power capacitors was insignificant compared to packaging inductance. Thermal and electrical modelling and experimental measurements showed that corrosion effects could readily account for the generic catastrophic failure mode of metallised polypropylene capacitors. Modelling showed that remnant vestiges of metal bridging corrosion gaps between the schooping and the metallic film could also pose serious thermal danger to the affected capacitor. Fusing current modelling and experimental measurement showed that fusing in metallic films typically occurred for current densities of several hundred thousand amperes per square centimetre. The partial disconnection of the metallic layers from the schooping edge by corrosion for example, was shown to result in large increases in dissipation factor and power loss in a capacitor readily explaining how capacitors
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Vennerberg, Patrik. "Improvement of Routine Test Process of High Voltage Power Capacitors." Thesis, Högskolan Dalarna, Maskinteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4097.
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The capacitor test process at ABB Capacitors in Ludvika must be improved to meet future demands for high voltage products. To find a solution to how to improve the test process, an investigation was performed to establish which parts of the process are used and how they operate. Several parts which can improves the process were identified. One of them was selected to be improved in correlation with the subject, mechanical engineering. Four concepts were generated and decision matrixes were used to systematically select the best concept. By improving the process several benefits has been added to the process. More units are able to be tested and lead time is reduced. As the lead time is reduced the cost for each unit is reduced, workers will work less hours for the same amount of tested units, future work to further improve the process is also identified. The selected concept was concept 1, the sway stop concept. This concept is used to reduce the sway of the capacitors as they have entered the test facility, the box. By improving this part of the test process a time saving of 20 seconds per unit can be achieved, equivalent to 7% time reduction. This can be compared to an additional 1400 units each year.
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Kim, Jiseong. "Procedures for locating switched capacitors in electric power distribution systems /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Chen, Qiyu. "Coordinated scheduling of hydroelectric and wind power generation in power systems." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.680862.
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Wind generation has emerged as an important renewable resource for power systems in recent years. However, the stochastic availability and variability of wind make scheduled generation dispatch complex. Therefore, a Coordinated Hydro and Wind Generation (CHWG) strategy is proposed to improve scheduled dispatch and thereby contribute to preservation of system stability, while offering access to wind energy at grid level. The CHWG is described in detail and a feasibility study has been conducted. In CHWG strategy, the hydroelectric generation is proposed for energy reserve and compensation in the context of wind power fluctuation in order to avoid curtailment of wind generation to benefit wind providers. An optimal dispatch model for CHWG proposed, which includes a wind forecasting confidence interval and electricity tariff. The boundary constraint and inertia coefficient of a particle swarm optimization algorithm are adopted and used to solve the optimal dispatch model. The model is applied to a wind farm system in North China to exemplify the proposed strategy. The following work and achievements are related to the use of the CHWG method. CHWG enhances the capacity of peak load regulation with offshore wind power integration. A model is presented to study the capacity of peak load regulation with offshore wind power integration. Meantime, a CHWG strategy mode is adopted to provide peak load regulation and some measures are proposed to improve regulation. A power system model is used to demonstrate that wind power fluctuations can readily render Over-frequency generator tripping (OFGT) and under-frequency load shedding (UFLS) mal-operation. Using the proposed CHWG strategy, a coordinated approach is proposed to resolve problems associated with OFGT and UFLS and preserve system stability. Finally, a risk assessment model (RAM) for wind generator tripping is established and verified by simulation results from a provincial Power Grid of China on line data.
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Gallé, William Preston. "MEMS-based fabrication of power electronics components for advanced power converters." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45821.
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Fabrication technology, based on MEMS processes, for constructing components for use in switched-mode power supplies are developed and presented. Capacitors, magnetic cores, and inductors based on sacrificial multilayer electroplating are designed, fabricated, and characterized. Characterization of the produced inductors' core losses at high frequency and high flux is presented, confirming the aptness of the featured microfabrication processes for reducing eddy current losses in magnetic cores. As well, the demonstration of the same inductors in DC/DC converters at high switching frequencies, up to 6 MHz, is presented.
Initial work addressing the top-down development of a fully-integrated DC/DC converter is presented. As well, the comprehensive advancement of the central process - sacrificial multilayer electroplating - is presented, including the development of a second-generation automated multilayer electroplating system. The advanced sacrificial multilayer plating process is applied to produce microfabricated capacitors, which achieved in excess of 1.5 nF/mm² capacitance density,
The fabrication of highly-laminated magnetic cores and power inductors based on sacrificial multilayer electroplating is presented, along with the design and development of a system for characterizing inductor behavior at high-frequency, high-flux conditions. The design and operation of both buck and boost DC/DC converters, switching at up to 6 MHz, built around these highly-laminated-core inductors are presented.
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Arnold, David Patrick. "Magnetic Machines for Microengine Power Generation." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4854.
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This dissertation presents an investigation of miniaturized magnetic induction and permanent magnet (PM) machines, intended for use in a microengine. Similar to a macroscale turbogenerator, a microengine comprises a small, gas-fueled turbine engine for converting chemical fuel energy into mechanical power and an integrated electrical generator for converting mechanical power to electrical power. The microengine system is proposed as a revolutionary, high power-density source for portable electronics.
In this research, miniaturized magnetic induction machines and PM machines were designed, fabricated, and characterized. Both types of machines used axially directed magnetic fields and were nominally 10 mm in diameter and 1.5-2.3 mm in thickness. Innovative microfabrication techniques were developed to demonstrate the feasibility of integrating magnetic machines within a bulk-micromachined, silicon-based microengine system.
Two-phase, eight-pole induction machines were constructed within silicon substrates using Cu coils in a laminated, slotted ferromagnetic NiFe or CoFeNi stator core. Silicon etching, wafer bonding, and electrodeposition were used to form all of the magnetic machine components. The induction machines were characterized in motoring mode using tethered rotors and demonstrated motoring torques of up to 2.5 uN-m.
Also, three-phase, eight-pole, surface wound PM machines were built using a hybrid microfabrication/assembly approach. The stators were fabricated by electroplating Cu coils on ferromagnetic NiFeMo (Moly Permalloy) substrates. The rotors were formed by assembling a magnetically patterned SmCo PM with a FeCoV (Hiperco 50) back iron. The PM machines were tested as generators with free-spinning rotors, powered by an air-driven spindle, and demonstrated 2.6 W of mechanical-to-electrical power conversion with continuous DC power generation of 1.1 W at 120 krpm rotor speed.
The primary contributions of this work are (1) the demonstration of microfabricated magnetic machines integrated within bulk-micromachined silicon and (2) the demonstration of multi-watt power conversion from a microfabricated PM generator. These achievements represent progress in the ongoing development of silicon-based microengines, but in addition, the fabrication technologies and device structures may find application in other microsystems.
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Williams, Orla. "On biomass milling for power generation." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33464/.
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Biomass combustion has increasingly been used in pulverised fuel coal fired power stations as a way of addressing a wide range of emissions reduction targets. The reuse of existing equipment such as coal mills is essential to minimise the costs of conversion. However the fundamental fracture mechanics involved in biomass comminution are completely different to coal. Thus a thorough knowledge of the comminution properties of all biomass types in coal and biomass mills is necessary in order to minimise operational issues and to optimise milling and combustion. This thesis provides extensive novel characterisation on densified biomass before and after milling. The study analysed 9 densified biomasses, 2 non-densified biomasses, and a sample coal in five different mills; planetary ball mill, Hardgrove Grindability Index testing mill, Bond Work Index ball mill, cutting mill, and a ring-roller mill. Milling was found to have little impact on particle shape, even when an order of magnitude change in particle size was observed. Particle shape is inherent to the particles which comprise a pellet, and is determined by the pre-densified comminution processes. Milling had little impact on compositional particles of herbaceous or wood pellets. Olive cake had the most spherical of all the materials. Thermal pre-treatments of woody biomass not only saw a significant improvement in grindability in all mills, but also enhanced shape factors. The Hardgrove Grindability Index is a poor indicator of the grindability of biomass. The Bond Work Index can be used to analyse the choking potential of biomass pellets prior to full scale mill trials. To optimise milling in coal mills, biomass pellets should be composed of particles close to the required size so that only the pellet comminution stage occurs. The milling behaviour of densified biomass in a laboratory scale ring-roller mill with dynamic classification was investigated for the first time. The milling studies showed that knowledge of a materials critical particle size for comminution through compression is essential to understand its milling behaviour in different mills. The results presented in this thesis not only provide new insight and addresses significant gaps in knowledge, they also provide useful and practical guidance for addressing operational issues such as mill choking, as well as ways to optimise biomass comminution in laboratory and full scale mills, such as mill classifier optimisation based on real particle characteristics.
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Abbott, Stephen. "Reactive power dispatch using distributed generation." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602402.
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Migrating from a legacy network, designed for centralised power production and control, to a network topology which allows for the integration of central and distributed generation has many challenges, The evolution of the network has to overcome the problems associated with integration of distributed generation (DG), These problems include the management of the network's voltage, reactive and active power flows, fault current, power quality and voltage stability issues, In this thesis a solution to the voltage control issue using reactive power dispatched from distributed generation is explored, This study predominantly presents a novel coordinate control stratagem utilising a sensitivity control algorithm to dispatch reactive power from distributed generation, The control stratagem is demonstrated on a balanced version of the IEEE 13 bus feeder, where it is shown to not only have the capability to maintain network voltages within the statutory limits, but also to reduce the requirement for network reinforcement and allow for greater accommodation of further distributed generation, The physical differences of unbalanced networks, and thus the requirement for an enhanced unbalanced controller, are presented for the unbalanced IEEE 13 node test feeder and Scottish and Southern Energy's We stray network. It is noted that unbalanced networks need to establish reactive power support for individual phases to ensure that networks operate within unbalanced limits, This is particularly necessary when stochastic generation is accommodated on the network. Proposals are presented for the connection of dynamic var (DVAr) compensation to ensure that the voltage imbalances, which will occur due to the connection of the proposed DG on the Westray system, are within the network requirements, It is also shown that the need for DVAr support can be elevated if the closure of the open point is allowed and the control strategy is utilised, From this work it is envisaged that dispatching reactive power from distributed generation could form an integral part of future networks if they too are operated effectively, efficiently and within voltage limitations, To allow this to happen, a number of changes to how distribution networks are operated and how DG is connected and compensated are required, The research highlights the importance of real-time monitoring and control of reactive power to better utilise the existing transmission and distribution infrastructure, whilst ensuring security and quality of power supply, It is further emphasised that adequate reward schemes or mandates for reactive power need to be implemented if sufficient reactive power is to be procured for network voltage support.
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McNamara, Fergal. "Improved generation dispatch in power systems." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46443.
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Sheu, Elysia J. (Elysia Ja-Zeng). "Hybrid solar-fossil fuel power generation." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78189.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 83-92).<br>In this thesis, a literature review of hybrid solar-fossil fuel power generation is first given with an emphasis on system integration and evaluation. Hybrid systems are defined as those which use solar energy and fuel simultaneously, thus excluding the viable alternative of solar thermal plants which use fossil fuels as backup. The review is divided into three main sections: performance metrics, the different concentrated solar receiver technologies and their operating conditions, and the different hybridization schemes. In addition, a new linear combination metric for analysis of hybrid systems, which considers trade-off of different metrics at the fleet level, is presented. This metric is also compared to alternative metrics from multi-objective optimization. Some previous work only evaluates the hybrid cycle at a certain point in time, which can be misleading as this evaluation would not take into account certain aspects of hybrid cycle such as fluctuating solar supply. Furthermore, almost all previous work designs the hybrid solar-fossil fuel systems for a certain point in time and then evaluates the performance of the system for an entire year. By not taking into account fluctuating solar supply and selling price of electricity in the design of the system, the best possible annual performance of the hybrid cycle may not be reached. Second, an analysis of solar reforming as the integration method for the hybrid cycle is presented, in particular steam reforming of methane. Two solar reforming systems are analyzed: one with a parabolic trough and the other with a solar tower. From the analysis, it is determined that parabolic troughs are not suitable for steam reforming due to the relatively low operating temperatures. The tower reformer system is integrated with a standard combined cycle, and the design and operation of the hybrid cycle is optimized for highest work output for a fixed fuel input and solar collector area (essentially optimizing for maximum cycle efficiency). A heuristic two step procedure is used for the optimization due to the limitation of the optimizer which cannot simultaneously optimize both design and operation. From the optimization, it is determined that the tower reforming integration method is a promising integration option in that this type of hybrid cycle yields high incremental solar efficiencies and also satisfies the linear combination metric for efficiency and CO₂ emissions (i.e., the analyzed hybrid cycle has a higher efficiency for a fixed CO₂ emissions compared to a linear combination of solar only and fossil fuel only cycles).<br>by Elysia J. Sheu.<br>S.M.
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Mischenko, Alexandre. "On-chip cooling and power generation." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612857.
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Azmi, Syahrul Ashikin. "Grid integration of renewable power generation." Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23161.
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This thesis considers the use of three-phase voltage and current source inverters as interfacing units for renewable power, specifically photovoltaic (PV) into the ac grid. This thesis presented two modulation strategies that offer the possibility of operating PV inverters in grid and islanding modes, with reduced switching losses. The first modulation strategy is for the voltage source inverter (VSI), and exploits 3rd harmonic injection with selective harmonic elimination (SHE) to improve performance at low and high modulation indices, where the traditional SHE implementation experiences difficulties due to pulse dropping. The simulations and experimentation presented show that the proposed SHE allows grid PV inverters to be operated with less than a 1kHz effective switching frequency per device. This is vital in power generation, especially in medium and high power applications. Pulse dropping is avoided as the proposed modified SHE spreads the switching angles over 90°, in add ition increasing the modulation index. The second proposed modulation strategy, called direct regular sampled pulse width modulation (DRSPWM), is for the current source inverter (CSI). It exploits a combination of forced and natural commutation imposed by the co-existence of an insulated gate bipolar transistor in series with a diode in a three phase current source inverter, to determine device dwell times and switching sequence selection. The DRSPWM strategy reduces switching frequency per device in a CSI by suspending each phase for 60°, similar to VSI dead-band, thus low switching losses are expected. Other benefits include simple digital platform implementation and more flexible switching sequence selection and pulse placement than with space vector modulation. The validity of the DRSPWM is confirmed using simulations and experimentation. This thesis also presents a new dc current offset compensation technique used to facilitate islanding or grid operation of inverter based distributed generation, with a reduced number of interfacing transformers. The proposed technique will enable transformerless operation of all inverters within the solar farm, and uses only one power transformer at the point of common coupling. The validity of the presented modulation strategies and dc current offset compensation technique are substantiated using simulations and experimentation.
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Schofield, Daniel M. K. "Power converters for photovoltaic energy generation." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7029/.
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Global demand for renewable energy has provided impetus for increased research into photovoltaic (PV) technology. Photovoltaic modules have intrinsically low efficiency and therefore, to maximise generated electricity, advances must be made in the efficient extraction of energy to maintain viability of their use. In this thesis, efficiency is maximised using novel power electronics. To facilitate advanced design, novel methods for generating accurate models of PV generators are presented. Conventional methods rely on the characterisation of PVs under continuous illumination. These methods cause heating of the module which can degrade the performance below that which would be seen during normal operation. To counter this problem, the use of flashed illumination is presented as a method for unobtrusively generating a PV electrical characteristic which can be used for accurate model-parameter extraction. To develop optimised-switch mode power converters for PVs, the reasons for suboptimal operation in existing converters is analysed and validated experimentally. Whereas existing research has considered the effect of current perturbation at mains frequency, this thesis extends the analysis to 500 kHz, which represents typical switchmode operation. A typical boost converter cannot meet the requirements for optimal power extraction from the PV module and therefore a novel circuit topology based on a SEPIC converter which can achieve optimal conditions is developed and presented. Since the methods for power transfer optimisation presented in this thesis require that the additional hardware is implemented in order to take full advantage of the PV generator, a method is presented whereby the resulting increased cost is significantly reduced. This reduction is achieved through the adaptation of redundant computer power supplies for PV battery charging applications, a method which can be used to produce a PV battery charger with minimal material or design investment.
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Unni, Vineet. "Next-generation GaN power semiconductor devices." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11984/.
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Kyaw, Phyo Aung. "Efficient Power-Dense Passive Components for Next-Generation High-Frequency Power Conversion." Thesis, Dartmouth College, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10978933.
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<p> Advancements in energy systems and electric vehicles have increased demands for efficient and compact power electronics. High-frequency operation is important for miniaturization of switching power converters since it reduces energy storage requirement and improves transient performance. Wide-bandgap semiconductors allow for efficient high-frequency switching, but full realization of their potential in power electronics requires efficient power-dense high-frequency passive components. Magnetic components such as inductors and transformers, due to their frequency-dependent losses, are increasingly the main bottleneck in improving the density of power converters. </p><p> Although incremental improvements in magnetics, and passives in general, are enabling advances in power electronics, the importance of the problem merits consideration of the fundamental performance limits and exploration of alternative passive component technologies. Analysis of various energy storage mechanisms indicates the potential of mechanical storage coupled with a piezoelectric transduction mechanism. Optimally designed piezoelectric and electromagnetic resonators, in ideal scenarios, are capable of orders-of-magnitude higher power density than passive components in use today. Investigation of various practical limitations provides insights into possible technological development for improving the performance of passive components and switching converters. </p><p> High-performance resonant tanks and power converters are also presented. First, an integrated LC resonator with a multilayer foil winding demonstrates 50% better performance compared to a similar resonator with a single-layer skin-effect limited winding. Second, an optimally designed integrated LC resonant tank, made of commercial Class I ceramic capacitors, has a sub-m? effective series resistance and incurs only 4.56 W loss, resulting in a 7.42 kW power capability in a small 1.14 cm<sup>3</sup> volume. The high performance means that a power converter utilizing these prototype resonators will be limited by the performance of switches rather than by the passive component. Finally, a prototype 48 V to 16 V stacked-ladder converter, with a high active device utilization figure of merit, combined with a small low-loss integrated resonator, provides a peak efficiency of 97.8% and a high power density of 913 W/in<sup>3</sup>. The theoretical analysis, together with these prototypes, shows the potential for significant improvement in the efficiency and power density of high-frequency switching converters, and the various technological developments required to achieve such improvements.</p><p>
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Quillen, Chris A. "Analysis of reactive power compensation methods in distribution systems a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=2&did=1913184261&SrchMode=1&sid=2&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1264100685&clientId=28564.
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Uz, Eda. "Design And Implementation Of Thyristor Switched Shunt Capacitors." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611616/index.pdf.
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This research work deals with the analysis, design and implementation of thyristor switched plain capacitor banks and thyristor switched shunt filter banks. Performances of various thyristor switched capacitor (TSC) topologies are also investigated by simulations. The theoretical findings have been verified by carrying out experimental work on two prototypes implemented within the scope of this research work, one is a wye-connected laboratory prototype and the other is a delta-connected application prototype integrated to some of the SVCs existing in Turkish Coal Enterprise s Plants. The advantages of back-to-back connected thyristor switches over conventional electromechanical contactors are also made clear by conducting an intensive experimental work in the laboratory. A good correlation have been obtained between theoretical and experimental results.
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Paaso, Esa A. "Coordinated Voltage and Reactive Power Control of Power Distribution Systems with Distributed Generation." UKnowledge, 2014. http://uknowledge.uky.edu/ece_etds/40.
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Distribution system voltage and VAR control (VVC) is a technique that combines conservation voltage reduction and reactive power compensation to operate a distribution system at its optimal conditions. Coordinated VVC can provide major economic benefits for distribution utilities. Incorporating distributed generation (DG) to VVC can improve the system efficiency and reliability. The first part of this dissertation introduces a direct optimization formulation for VVC with DG. The control is formulated as a mixed integer non-linear programming (MINLP) problem. The formulation is based on a three-phase power flow with accurate component models. The VVC problem is solved with a state of the art open-source academic solver utilizing an outer approximation algorithm. Applying the approach to several test feeders, including IEEE 13-node and 37-node radial test feeders, with variable load demand and DG generation, validates the proposed control.
Incorporating renewable energy can provide major benefits for efficient operation of the distribution systems. However, when the number of renewables increases the system control becomes more complex. Renewable resources, particularly wind and solar, are often highly intermittent. The varying power output can cause significant fluctuations in feeder voltages. Traditional feeder controls are often too slow to react to these fast fluctuations. DG units providing reactive power compensation they can be utilized in supplying voltage support when fluctuations in generation occur. The second part of this dissertation focuses on two new approaches for dual-layer VVC. In these approaches the VVC is divided into two control layers, slow and fast. The slow control obtains optimal voltage profile and set points for the distribution control. The fast control layer is utilized to maintain the optimal voltage profile when the generation or loading suddenly changes. The MINLP based VVC formulation is utilized as the slow control. Both local reactive power control of DG and coordinated quadratic programming (QP) based reactive power control is considered as the fast control approaches. The effectiveness of these approaches is studied with test feeders, utility load data, and fast-varying solar irradiance data. The simulation results indicate that both methods achieve good results for VVC with DG.
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Li, L. "Maximum power control of permanent magnet synchronous generator based wind power generation systems." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3006695/.
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Jayakumar, Ramkumar. "Analysis of power generation processes using petcoke." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2802.
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Yalcinoz, Tankut. "Computational intelligence applied to power generation dispatch." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/8257.
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Jabr, Rabih Adel. "Interior-point methods for power generation dispatching." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/8428.
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Cooke, Susannah. "Enhanced array design for tidal power generation." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:cdce19c8-dad4-4f2d-8432-d6b6c41eb927.
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Tidal stream energy is a predictable source of renewable energy. Tidal stream turbines have been proposed as a way to extract useful energy from the tide. Many arrays of such devices will need to be installed to extract significant amounts of energy. The presence of an array of turbines within a tidal flow will impact the flowfield, as complex fluid interactions occur across multiple scales. This thesis is concerned with the behaviour of tidal turbines arrayed across channels. Experimental and analytical work is carried out to investigate array behaviour and to create new modelling tools to replicate this behaviour. Linear Momentum Actuator Disc Theory (LMADT) is employed to develop a new analytical model for a long row array of tidal turbines split into multiple smaller, co- linear row arrays. An argument of separation of scales is used to facilitate this model. It is found that increases in power extraction beyond that of a single continuous row array are possible. Experimental work is carried out on a row array of eight porous discs, simulating a short row array of tidal turbines. Disc porosity and spacing are varied to investigate thrust on the array, flow behaviour behind the array and an 'inferred' power removed from the flow. The results are compared to previously developed theoretical models. Good agreement is found with the trends of the analytical model, for example that there is a peak power coefficient which can be reached through appropriate selection of spacing and disc resistance. Differences from theory are found in the total thrust and power measurements, as well as in some aspects of the flow behaviour in the array wake. Reductions in thrust and power towards the ends of the array are also identified as 'end effects' which are not included in the analytical model. Based on these results a new semi-empirical model is proposed, using LMADT with experimental data closure. This model allows variation of the disc resistance across a row array. Values from the experimental work are used as inputs to the model, and the results compared to experimental measurements of flowspeed, thrust and power. Although agreement with experimental results is found in some areas, there are still some discrepancies between the analytical model and the experimental results. This indicates that there are additional factors that contribute to end effects on a short row array.
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Tsai, Peng Fei, and 蔡鵬飛. "Investigation of the Stability Improvement in Power Generation of High Concentration Photovoltaic System with Super-capacitors." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/98107882221542858583.
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碩士<br>國立金門大學<br>電子工程學系碩士班<br>101<br>The Super-capacitor component is proposed to be integrated into HCPV system. The proposed architecture is expected to improve the unstable power generation phenomenon caused by vibration of HCPV’s solar tracking system. The vibration is usually caused by wind or unstable sensor, which is interfered by cloud and noise. If regulator circuit or components can be integrated into HCPV system to regulate the voltage of photovoltaic receivers’ output, it will improve HCPV system’s stability and power generation.
In the Chap two of this thesis, we construct the Tomas’s equivalent circuit of solar cell with super-capacitor which was published in R.M. Nelms’s research paper. The improvement of circuit’s stability with super-capacitor is evaluated by PSpice simulation. The simulation is divided into three segments: the first one is output stability improvement evaluation; the second one is super-capacitor evaluation; and the third one evaluates the tracking angle deviation. The power generation will decrease around 48%. The power generation loss will be improved to 5.4% by adding 5F super-capacitor in the circuit. In addition, the simulation result demonstrates that different value of super-capacitors will cause different stability duration. Therefore, we can choose suitable value for the different conditions.
In the Chap three of this thesis, experiments are carried out to evaluate the simulation results of Chap two. The experiments are divided into two segments: with and without output loading of the solar cell circuit. The output voltage of θ=3° is still within the spec of accept angle (remains 90% output power). The output voltage decreases a little compared to the output voltage of solar cell circuit without resistance loading. Therefore, it is concluded that by adding 5F super-capacitor to the circuit with or without resistance loading, the output voltage could sustain more than 89.8% with deviation angle θ=2°.
This research analyzes and simulates the effect of integrating super-capacitor circuit to HCPV system. The circuit model and simulation parameters of the proposed system are built and investigated. The efficiency and stability of HCPV system’s power generation could be improved by implementation of the proposed model of this research. In addition, the process of integrating super-capacitor to HCPV system can be developed via this project. Moreover, this project proposes a novel application of the super-capacitor with photovoltaic system.
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Gassner, Andy. "Sizing storage and wind generation capacities in remote power systems." Thesis, 2010. http://hdl.handle.net/1828/3618.
Full textAbstract:
Global adoption of renewable energy is increasing due to growing concern over climate change, increasing costs associated with conventional generation, and decreasing capital investment costs of renewable energy technologies. Specifically, wind power represents the most technologically mature renewable alternative and is recognized as a cost effective generation source in both large and small power systems. However, the variability due to the stochastic nature of the wind resource introduces technological limitations to the amount of wind power which can be integrated in a power system. Energy storage is seen as a solution to mitigate the variability in wind power output.
Wind power and energy storage devices have the potential to contribute a substantial amount of renewable generation to meet the electricity demand in remote power systems. Remote power systems are characterized by their self reliance on electrical generation. The basic function of a remote power system is to provide the necessary power to satisfy the community’s electricity demand requirements as economically as possible with an adequate level of continuity and reliability.<br>Graduate
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Garcia, Arregui Marcos. "Theoretical study of a power generation unit based on the hybridization of a fuel cell stack and ultra capacitors." Phd thesis, 2007. http://oatao.univ-toulouse.fr/7617/1/garcia_arregui.pdf.
Full textAbstract:
The presented work deals with the design and conception of an electrical network from a fuel cell stack and its associated storage device. The framework of this project is an aeronautical and transport application. Air pressurized fuel cell stacks need some auxiliary devices that permits a correct gas flow through the fuel cell stack. Due to the auxiliary devices, the fuel cell dynamics performances may be limited, and a power buffer is required to support power peaks. Furthermore, hybridization has a positive effect in the system size, and can lead to reduce the global system weight and volume. Ultracapacitors seem to be well adequate for this purpose. Nevertheless, the introduction of a storage device in the electrical network opens a wide range of possible architectures. Indeed, due to the important voltage variations of the supercapacitor bank and the fuel cell stack, some power electronics interfaces may be placed in order to assure the electrical network requirements. Thus, the system behaviour varies according to the position of the power converters and the storage device in the electrical network. Therefore, the power converter conception, the retained electrical architecture characteristics and its associated control laws are studied in this work. Due to the transport application, the system hydrogen consumption, volume, weight and cost are essential parameters, and become the key to choose one of the retained architectures. Furthermore, the system couplings and the important number of design variables makes impossible to design the system without the help of a software tool. Therefore, and in order to compare fairly all the proposed architectures, a multiobjective optimization tool is developed
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Yu, Wen-Yi, and 游文毅. "ANALYSIS OF CAPACITOR INSTALLATION AND VOLTAGE REGULATION FOR DISTRIBUTION POWER SYSTEM WITH DISPERSED GENERATION." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/85466877166890631966.
Full textAbstract:
碩士<br>大同大學<br>電機工程學系(所)<br>94<br>ABSTRACT
The so-called Distributed Power Generation or Dispersed Power
Generation System refers to small power generator that is closed to the
load terminal and the power generation capacity is comparatively less. It
can be formed as area power supply system or can be connected in
parallel to large-scale power system.
For distribution in the past, the Taipower would supply a one-way
power, therefore this was simpler in respect of control, management,
repair or fee collection. However, when there are many dispersed power
generation systems (abbreviated as DG) on the circuit in parallel
connection. At this time, the reliability of the power supply of the
distribution system and the maintenance of power quality and
maintenance of personnel and equipment safety will be more complex
and it will cause impact on the existing distribution system.
This thesis adopts a feeder of Taipower as the research target. The
substation main transformer specification is 3∮69KV/22.8KV 25MW
that provides power for eight nodes. Based on the existing data and after
computer program simulation, one can understand that for the present
utilization of that feeder, the voltage of various nodes can still conform
to the provision of the permissible value of voltage. However, in the
future, that feeder may encounter situation. Beforehand we can adopt
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computer program simulation. And the author will base on the traditional
method of Taipower and that is general estimate principle to find out the
possible establishment position and capacity of the capacitor on that
feeder. In addition, computer simulation is utilized to prove that the
estimate principle in the traditional way of Taipower is not applicable to
various conditions.
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Wu, Horng-Yuan, and 吳鴻源. "Study of Photovoltaic Generation System with Active Power Filter Using Reduced Energy- Storage Capacitor." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/62610483252895459231.
Full textAbstract:
博士<br>國立高雄應用科技大學<br>電機工程系<br>98<br>Abstract
In this dissertation, the subjects on maximum power point tracking (MPPT) technique and the shield effect of the grid connected photovoltaic generation system are studied. At first, a novel MPPT technique based on perturb and observe scheme is presented. The method uses the pulse width modulation signal of the boost converter as perturbation source. With comparing other MPPT technology, the proposed MPPT technique tracks the maximum power without disturbing the operation condition and has the excellent response. Secondly, a FPGA based SVPWM inverter is used to connect an electric utility and provides the AC power output.
The inverter operates in dual mode: It is operated in the generation mode at sunlight to provide the AC power output, and the inverter is switched into the active power filter (APF) mode during the night or the day without sunshine in order to improve the power quality. With this operation manner, it is able to increase the utilization ratio of equipments.
The APF uses the sampling technique to simplify the calculation of fundamental current. By using the sampling technique with energy balance concept, the APF could use a smaller storage capacitor and controls the terminal voltage of the storage capacitor within the reference range. The advantages of this APF scheme are: (1) Low prices (Using smaller storage capacitor), (2) Excellent transient response.
A theoretical analysis and the design principle of the proposed method are provided. Its feasibility is verified by simulation (Matlab-Simulink and Pspice). Also, a 750W photovoltaic generation system is constructed for testing. The simulation and experimental results reveal that they have good steady state and transient responses.