Dissertationen: „Power generation circuit“

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Krishnamurthy, Smitha. „SOLAR AND FUEL CELL CIRCUIT MODELING, ANALYSIS AND INTEGRATIONS WITH POWER CONVERSION CIRCUITS FOR DISTRIBUTED GENERATION“. Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3501.

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Renewable energy is considered to be one of the most promising alternatives for the growing energy demand in response to depletion of fossil fuels and undesired global warming issue. With such perspective, Solar Cells and Fuel Cells are most viable, environmentally sound, and sustainable energy sources for power generation. Solar and Fuel cells have created great interests in modern applications including distributed energy generation to provide clean energy. The purpose of this thesis was to perform a detailed analysis and modeling of Solar and Fuel cells using Cadence SPICE, and to investigate dynamic interactions between the modules and power conversion circuits. Equivalent electronic static and dynamic models for Solar and Fuel Cells, their electrical characteristics, and typical power loss mechanisms associated with them are demonstrated with simulation results. Power conversion circuits for integration with the dynamic models of these renewable low voltage sources are specifically chosen to boost and regulate the input low dc voltage from the modules. The scope of this work was to analyze and model solar and fuel cells to study their terminal characteristics, power loss mechanisms, modules and their dynamics when interfaced with power converters, which would lead to better understanding of these renewable sources in power applications.
M.S.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE

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Kim, Jina. „Area and Power Conscious Rake Receiver Design for Third Generation WCDMA Systems“. Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/30972.

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A rake receiver, which resolves multipath signals corrupted by a fading channel, is the most complex and power consuming block of a modem chip. Therefore, it is essential to design a rake receiver be efficient in hardware and power. We investigated a design of a rake receiver for the WCDMA (Wideband Code Division Multiple Access) system, which is a third generation wireless communication system. Our rake receiver design is targeted for mobile units, in which low-power consumption is highly important. We made judicious judgments throughout our design process to reduce the overall circuit complexity by trading with the performance. The reduction of the circuit complexity results in low power dissipation for our rake receiver. As the first step in the design of a rake receiver, we generated a software prototype in MATLAB. The prototype included a transmitter and a multipath Rayleigh fading channel, as well as a rake receiver with four fingers. Using the software prototype, we verified the functionality of all blocks of our rake receiver, estimated the performance in terms of bit error rate, and investigated trade-offs between hardware complexity and performance. After the verification and design trade-offs were completed, we manually developed a rake receiver at the RT (Register Transfer) level in VHDL. We proposed and incorporated several schemes in the RT level design to enhance the performance of our rake receiver. As the final step, the RT level design was synthesized to gate level circuits targeting TSMC 0.18 mm CMOS technology under the supply voltage of 1.8 V. We estimated the performance of our rake receiver in area and power dissipation. Our experimental results indicate that the total power dissipation for our rake receiver is 56 mW and the equivalent NAND2 circuit complexity is 983,482. We believe that the performance of our rake receiver is quite satisfactory.
Master of Science

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Afifi, Sara Nader. „Impact of hybrid distributed generation allocation on short circuit currents in distribution systems“. Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/15195.

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The rapid development in renewable generation technologies and flexible distribution networks requires current infrastructure to be modified and developed to adapt high penetration levels of distributed generation. Existing distribution networks were not initially designed and anticipated to accommodate generators on large scale. Short circuit studies ensure the effectiveness of protection equipment settings and coordination is maintained in case of short circuit, despite any additional distributed generation is connected to the distribution network. This research aims to study and compare the different network fault situations for wind energy systems with induction generators, photovoltaic energy systems, and diesel generators connected to distribution networks. The simulation study will be conducted on the existing IEEE case study systems including 13 bus and 30 bus distribution test systems, using ETAP software. Short circuit analysis will be performed twice to include the ANSI/IEEE and the IEC methods for short circuit currents calculation. Simulated results showed that the wind energy systems have significant impact on the short circuit currents, whereas the photovoltaic energy systems are found to have inconsequential effect. The most moderate solution is found to be a distributed generation mix.

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Wang, Shen. „Design and Analysis of a Low-Power Low-Voltage Quadrature LO Generation Circuit for Wireless Applications“. Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/39301.

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The competitive market of wireless communication devices demands low power and low cost RF solutions. A quadrature local oscillator (LO) is an essential building block for most transceivers. As the CMOS technology scales deeper into the nanometer regime, design of a low-power low-voltage quadrature LO still poses a challenge for RF designers. This dissertation investigates a new quadrature LO topology featuring a transformer-based voltage controlled oscillator (VCO) stacked with a divide-by-two for low-power low-voltage wireless applications. The transformer-based VCO core adopts the Armstrong VCO configuration to mitigate the small voltage headroom and the noise coupling. The LO operating conditions, including the start-up condition, the oscillation frequency, the voltage swing and the current consumption are derived based upon a linearized small-signal model. Both linear time-invariant (LTI) and linear time-variant (LTV) models are utilized to analyze the phase noise of the proposed LO. The results indicate that the quality factor of the primary coil and the mutual inductance between the primary and the secondary coils play an important role in the trade-off between power and noise. The guidelines for determining the parameters of a transformer are developed. The proposed LO was fabricated in 65 nm CMOS technology and its die size is about 0.28 mm2. The measurement results show that the LO can work at 1 V supply voltage, and its operation is robust to process and temperature variations. In high linearity mode, the LO consumes about 2.6 mW of power typically, and the measured phase noise is -140.3 dBc/Hz at 10 MHz offset frequency. The LO frequency is tunable from 1.35 GHz to 1.75 GHz through a combination of a varactor and an 8-bit switched capacitor bank. The proposed LO compares favorably to the existing reported LOs in terms of the figure of merit (FoM). More importantly, high start-up gain, low power consumption and low voltage operation are achieved simultaneously in the proposed topology. However, it also leads to higher design complexity. The contributions of this work can be summarized as 1) proposal of a new quadrature LO topology that is suitable for low-power low-voltage wireless applications, 2) an in-depth circuit analysis as well as design method development, 3) implementation of a fully integrated LO in 65 nm CMOS technology for GPS applications, 4) demonstration of high performance for the design through measurement results. The possible future improvements include the transformer optimization and the method of circuit analysis.
Ph. D.

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Dam, Quang Binh. „Operating strategies to preserve the adequacy of power systems circuit breakers“. Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28232.

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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Divan, Deepakraj M.; Committee Member: Harley, Ronald G.; Committee Member: Johnson, Ellis L.; Committee Member: Taylor, David G.

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Fradinho, Bastos Ivan. „Marketing Introduction Plan for the New Generation of Sustainable Circuit Breakers LTA 420 kV : A real-life case for implementation at Hitachi ABB Power Grids“. Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297294.

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En strömbrytare är en säkerhetsanordning som är utformad för att bryta strömmen om ett problem uppstår. Det finns ett flertal olika typer av brytare beroende vilket spänningsområde som avses. Brytare för lågspänning används för hushållsapparater, medan högspänningstyper används för överföring av spänning i elnätet. Högspänningsbrytare använder idag svavelhexafluorid (SF6)-gas, som ett isolerande medium för att släcka den elektriska ljusbåge som bildas när strömmen bryts. SF6 är dock problematiskt för miljön, då dess globala uppvärmningspotential (GWP) är 23 500 gånger högre jämfört med koldioxid (CO2). Företaget Hitachi ABB Power Grids har utvecklat AirPlus™-tekniken som ersätter SF6-gasen med en koldioxidbaserad gasblandning. Examensarbetet fokuserade på att utvärdera möjligheten att minska användningen av SF6 genom AirPlus™-tekniken och hur tekniken skulle kunna en introduceras på marknaden. Slutligen så utvecklades en strategi för hur detta skulle kunna ske. Studien innefattar den bakomliggande informationsinhämtningen och analysen av data, marknadsutvärdering och utvecklingen av marknadsstrategin. Detta utfördes genom att utvärdera AirPlus™-tekniken och dess konkurrenter, samt genom en kvalitativ och kvantitativ analys av implementeringen av LTA 420 kV-brytaren på marknaden. Sammanfattningsvis så visar studien att marknadsintroduktionen av strömbrytaren LTA 420 kV är genomförbar. Även om koldioxid tekniskt inte har samma prestanda som SF6, är tekniken fortfarande bra och ger starka kundfördelar: GWP minskar med över 99,9%, användningen överensstämmer med miljöregler, den ger lägre ägandekostnader, färre kontroller, lägre kostnad för hantering av koldioxidgasen, och fungerar väl vid extremt låga temperaturer. De viktigaste utmaningarna för Hitachi ABB Power Grids relaterar till konkurrensen på marknaden. Det är därför tillrådligt att företaget arbetar med en effektiv marknadsintroduktion för att säkerställa en stor marknadsandel.
A circuit breaker is a safety device designed to interrupt power if a problem is detected. There are several kinds of circuit breakers for different applications. Low-voltage circuit breakers are used for household appliances, while high-voltage types are used for transmission networks. High-voltage circuit breakers use sulfur hexafluoride (SF6) gas as an insulating medium, which extinguishes the electric arc that is formed when power is cut. However, it is a huge hazard for the environment, as its global warming potential (GWP) is 23,500 times higher than that of CO2 gas. The company Hitachi ABB Power Grids developed the AirPlus™ technology, which replaces the SF6 gas with a carbon dioxide (CO2) based gas mixture. The presented degree project has evaluated the feasibility of reducing the use of SF6 through the AirPlus™ technology and then developed a strategy for the company Hitachi ABB Power Grids for the market introduction of the eco-efficient LTA 420 kV circuit breaker. This study covers the background research, market evaluation, and market strategy. It was done through research about the AirPlus™ technology and its competitors, so as qualitative and quantitative analysis of the LTA 420 kV circuit breaker implementation in the market. In conclusion, the study shows that the market introduction of the LTA 420 kV circuit breaker is feasible. Although CO2 is not as good an insulation medium as SF6, it is still good and presents strong customer benefits: GWP reduced by over 99.9%, compliance with new regulations, lower cost of ownership, fewer regulatory controls, reduced cost of handling the gas, and well-functioning at extremely low temperatures. The main concerns for Hitachi ABB Power Grids are related to market competition. Thus, it is advisable that the company works on an effective market introduction to assure a large market share.

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Petean, Daniel. „Metodologia para avaliação da influência de geradores distribuídos nos níveis de curto-circuito em sistemas de distribuição de energia“. Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-05082015-105752/.

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A instalação de geração distribuída nas redes de distribuição e de subtransmissão de energia elétrica tem apresentado significativo crescimento em âmbito mundial, impulsionada pelos benefícios que pode proporcionar aos sistemas elétricos, pela necessidade de diversificação da matriz energética dos países, pela desregulamentação do setor de energia elétrica em diversos países e pela necessidade de gerar energia elétrica de forma sustentável. No entanto, para que os geradores distribuídos possam de fato beneficiar a operação das redes elétricas, seus impactos técnicos devem ser cuidadosamente estudados, sobretudo em redes de distribuição, as quais foram inicialmente planejadas para operar com fluxo de potência unidirecional. Dentre esses impactos, destaca-se a elevação do nível de curto-circuito da rede, pois correntes de curto-circuito com valores elevados podem causar violação das capacidades dos equipamentos em suportar os esforços térmicos e dinâmicos e também provocar a perda da coordenação entre os dispositivos de proteção contra sobrecorrente. Neste contexto, este trabalho analisa a influência de geradores distribuídos baseados em inversores na corrente de curto-circuito trifásica em um sistema de distribuição de energia, e sobretudo, comprova que sua contribuição no valor da corrente de falta não supera o dobro de sua corrente nominal. Além disso, com base nesta comprovação, apresenta duas estratégias para inserção desse tipo de gerador nos cálculos de curto-circuito de um sistema de distribuição de energia elétrica. As duas estratégias apresentam resultados satisfatórios, utilizam conceitos básicos de circuitos elétricos, independem de dados minuciosos dos inversores e são validadas através de aplicações numéricas com resultados confrontados aos obtidos das simulações.
The installation of distributed generation in distribution and subtransmission systems has shown significant growth worldwide, driven by the benefits it can provide to electrical systems, the need to diversify the energy sources, deregulation of the electricity industry in several countries and the need to generate electricity in a sustainable manner. However, in order to evaluate if distributed generators benefit the operation of power networks, their technical impacts should be carefully studied, especially in distribution networks, which were originally designed to operate with unidirectional power flow. Among the aforementioned impacts, there is the increase of the short circuit level in the distribution network, since high short-circuit currents may exceed the capabilities of equipment to support the dynamic and thermal stresses and also cause loss of coordination between the overcurrent protection devices. Within this context, this thesis analyzes the influence of inverter based distributed generators on three-phase short circuit currents in a power distribution systems. Especially it confirms that the contribution to the fault current does not exceed twice its rated value. Furthermore, based on this issue, this work presents two strategies for the inclusion of this type of generator in short circuit calculations. Both strategies presented satisfactory results, use basic concepts of electrical circuits, they do not depend on detailed data from the inverters and the results are validated by using simulation results.

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Salomonsson, Daniel. „Modeling, Control and Protection of Low-Voltage DC Microgrids“. Doctoral thesis, Stockholm : Elektriska energisystem, Electric Power Systems, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4666.

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Silva, Rafael Schincariol da 1983. „Desempenho de geradores distribuídos durante curtos-circuitos considerando requisitos de suportabilidade a afundamentos de tensão = Distributed generators performance during short-circuits considering fault ride-through requirements“. [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259990.

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Orientador: Walmir de Freitas Filho
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: O aumento da penetração de geradores em redes de distribuição de energia elétrica além de diversificar a matriz elétrica proporciona benefícios técnicos e econômicos. Contudo, também levanta preocupações relativas à confiabilidade no suprimento de energia elétrica. Para plantas eólicas conectadas na média e alta tensão são estabelecidos requisitos de "Fault Ride-Through" que determinam que os geradores devem permanecer conectados à rede durante perturbações com afundamentos de tensão e, em alguns casos, fornecer reativos para o reestabelecimento da tensão terminal. Porém, implementar tais requisitos para geradores na baixa tensão não é trivial. Na ocorrência de grandes perturbações os geradores distribuídos devem obrigatoriamente ser desconectados em casos de ilhamento, caso contrário a segurança de pessoas e equipamentos é colocada em risco e a qualidade de energia fornecida não é garantida. Ainda, durante curtos-circuitos os geradores contribuem para ao aumento das correntes de falta e os esquemas de proteção podem sofrer impactos na seletividade e coordenação. Por isso, para atender o requisito de "Fault Ride- Through" seria necessário além de manter os geradores conectados rever os esquemas de proteção de sobrecorrente, sendo necessários estudos dos impactos desta iniciativa e a análise do comportamento dos principais tipos de geradores distribuídos na ocorrência de curtos-circuitos. Nesta dissertação de mestrado, uma rede de distribuição com geradores distribuídos foi analisada através do estudo de sucessivas simulações de transitórios eletromagnéticos. O comportamento de três tipos de geradores distribuídos na ocorrência de curtos-circuitos foi investigado por meio de estudos de estabilidade, da análise das características de afundamentos de tensão e do suporte de reativos. Os geradores síncronos se mostraram com maior capacidade de suportarem faltas temporárias na rede. Os impactos do aumento das correntes de falta nas proteções contra sobrecorrente e da não desconexão do gerador do sistema ilhado também foram analisados. Os resultados mostraram que a presença de geradores distribuídos pode causar problemas na seletividade e na coordenação da proteção, alem de deteriorar o comportamento transitório de geradores ilhados
Abstract: The increase of distributed generation penetration in distribution systems not only helps to diversify the electrical matrix but also brings both technical and economic benefits. Yet, it also raises worries related to energy supply reliability. For wind power plants into the medium and high voltage networks there are the grid codes for "Fault Ride-Through" which stands that wind generators ought to ride a fault with voltage sag and, in some cases, provide reactive power for the terminal voltage restoration. However, implementing such requisites for low voltage connected generators is not a trivial task, as under great perturbations the distributed generators are required to be disconnected from the grid if an islanding situation occurs. Otherwise, people and equipment security would be at risk and the quality of the supplied power cannot be guaranteed. Besides, during short-circuits generators contribute to the increased fault currents along the grid and because of that the protection schemes should experience loss of selectivity and coordination. So, meeting the fault ride-through requirement demand a review of the anti-islanding schemes in order to permit generator islanding, as well as review the protection schemes to guarantee selectivity and coordination. Therefore, studies about the impacts of this initiative are necessary as well as the main generators behavior analysis under short-circuits. In this dissertation, a distribution network was analyzed through successive electromagnetic transient simulations. The behavior of three types of distributed generators under shortcircuits was investigated by stability studies, voltage sag characteristics and reactive power support. Synchronous generators showed to present the best capability to ride through temporary faults on the grid. The impacts on overcurrent protection of increased shortcircuit currents due to the distributed generators and impacts of not disconnecting the generators during islanding situations were also analyzed. The outcomes showed that keeping distributed generators connected might lead to problems on the protection selectivity and coordination and deteriorate the transient behavior of generators
Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica

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Salgado, Danilo Augusto. „Uma abordagem paramétrica do impacto da geração distribuída sobre as correntes de curto-circuito e na proteção de redes de distribuição“. Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-20062016-083241/.

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Esta dissertação tem por propósito analisar os impactos da geração distribuída sobre as correntes de curto-circuito e sobre a proteção das redes de média tensão das concessionárias de distribuição de energia elétrica usando uma abordagem paramétrica. A principal motivação deste trabalho são os recentes incentivos regulatórios que estão fomentando a geração distribuída no Brasil. Contudo, as redes de distribuição convencionais foram projetadas para serem passivas e a introdução da geração poderá causar problemas de ordem técnica que ainda precisam ser resolvidos. Tais problemas foram pesquisados e aqueles relacionados com os impactos sobre as correntes de curto-circuito foram enfatizados. As normas técnicas das concessionárias também foram investigadas porque seus requisitos, como a ligação dos transformadores de acoplamento, influem nas correntes de curto-circuito. Para se calcular as correntes de curto-circuito, desenvolveu-se uma planilha eletrônica cujos resultados foram validados com programas comerciais de análise de redes elétricas. Esta ferramenta foi utilizada para demonstrar, através de exemplos, o impacto causado pela geração distribuída sobre as correntes de curto-circuito e, posteriormente, para realizar as análises paramétricas nas quais a influência de cada variável foi avaliada. A aplicação do método paramétrico permitiu o estudo de possíveis limites para a potência de um gerador distribuído em função dos impactos admissíveis, de seu ponto de conexão, de seus parâmetros elétricos e dos parâmetros elétricos da rede.
The purpose of this thesis is to analyse the impacts of distributed generation on short-circuit currents and protection of the distribution utilities medium voltage networks using a parametric approach. The new regulations that are promoting the distributed generation in Brazil are the main motivation for this work. However, the conventional distribution networks were designed to be passive; therefore the integration of generation may cause some technical problems yet to be solved. Such problems were researched and those related to the impacts on short-circuit currents were emphasized. The utilities technical standards were also explored as their requirements affect the short-circuit currents (e.g. the transformers connections). A spreadsheet was developed in order to calculated the short-circuit currents and it was validated comparing its results to those of a commercial network analysis software. This tool was used to expose the impacts of distributed generation on short-circuit currents through examples and also to carry out parametric analysis in which the influence of every variable was evaluated. The application of a parametric method made it possible to define the maximum installed capacity of a distributed generator as a function of the allowed limits to the impacts on the short-circuit currents, its point of coupling, its electrical parameters and the electrical parameters of the network.

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Deifelt, Samuel Vanderlei. „Análise da viabilidade técnica da operação de sistemas com geração distribuída no modo ilhado intencional“. Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/8584.

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The increasing demand for energy, coupled with the difficulties inherent in the implementation of large generation projects, significantly increased the use of energy resources from renewable energy sources, in order to better meet the energy market. Recent research shows that there are several benefits of using the Distributed Generation in relation to large enterprises Centralized Generation. In this sense, this work shows the results of studies conducted in order to verify the feasibility of taking advantage of the Distributed Generation to meet the remaining local loads in any power shortages Distributor. This operation is called Intentional Islanded Operation. In order to implement the intentional islanding operation of Distributed Generation, it is necessary to carry out specific studies to meet the levels of quality and continuity established by regulations and to ensure the safety of the electrical system. Thus, this work presents an analysis of the technical feasibility of intentional islanded operation of distributed generators, given the restrictions imposed resulting from Power Flow studies, Transient Stability and Short Circuit.
O crescente aumento da demanda de energia, associado às dificuldades inerentes à implantação de empreendimentos de geração de grande porte, aumentou significativamente o aproveitamento dos recursos energéticos a partir de fontes de energia renováveis, visando um melhor atendimento do mercado de energia. Pesquisas recentes mostram que há diversas vantagens em se utilizar a Geração Distribuída em relação aos grandes empreendimentos de Geração Centralizada. Neste sentido, esta dissertação mostra os resultados de estudos realizados com o objetivo de verificar a viabilidade em se aproveitar as Gerações Distribuídas para o atendimento das cargas locais remanescentes, em eventuais faltas de energia da Distribuidora. Esta operação é denominada de Operação Ilhada Intencional. Para que a operação ilhada de Geradores Distribuídos possa ser admitida, estudos específicos devem ser realizados, a fim de que os níveis de qualidade e continuidade exigidos pelos órgãos reguladores sejam atendidos e que a segurança do sistema elétrico seja preservada. Desta forma, esta dissertação apresenta uma análise da viabilidade técnica da operação ilhada intencional de Geradores Distribuídos, considerando as restrições resultantes impostas a partir de estudos de Fluxo de Potência, Estabilidade Transitória e Curto-Circuito.

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Potscavage, William J. Jr. „Physics and engineering of organic solar cells“. Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39634.

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Organic solar cells have the potential to be portable power sources that are light-weight, flexible, and inexpensive. However, the highest power conversion efficiency for organic solar cells to date is ~8%, and most high-efficiency solar cells have an area of less than 1 cm². This thesis advances the field of organic solar cells by studying the physics and engineering of the devices to understand the reverse saturation current, which is related to efficiency, and the effects of area scaling. The most commonly accepted models to describe the physics of organic photovoltaic devices are reviewed and applied to planar heterojunction solar cells based on pentacene / C60 as a model system. The equivalent circuit model developed for inorganic solar cells is shown to work well to describe the behavior of organic devices and parameterize their current-voltage characteristics with five parameters. Changes in the parameters with different material combinations or device structures are analyzed to better understand the operation of the presented organic solar cells. A one-dimensional diffusion model for the behavior of excitons and treatment of the organic layers as planes is demonstrated to adequately model the external quantum efficiency and photocurrent in pentacene / C60 solar cells. The origin of the open-circuit voltage is studied using cells with different electrodes and different donor materials. While changing the electrodes does not affect open-circuit voltage, it is greatly modified by changes in the donor. Tests with additional semiconductors show the change in open-circuit voltage is not consistent from donor to donor as the acceptor is varied, suggesting a more complex relation than just the difference in energy levels. Study of the temperature dependence of the equivalent circuit parameters shows that the reverse saturation current, which has a significant role in determining the open-circuit voltage, has a thermally activated behavior. From this behavior, the reverse saturation current is related back to charge transfer at the donor / acceptor heterojunction to suggest that both the effective energy barrier presented by the energy levels and the electronic coupling are important in determining the reverse saturation current and open-circuit voltage. This marks a shift from just considering a built-in voltage or the energy levels to also considering the electronic coupling of the donor and acceptor materials. Temperature-dependent performance characteristics are also used to show key differences between organic and inorganic devices. Finally, the effect of area scaling is explored with pentacene / C60 solar cells having areas of 0.11, 7, and 36.4 cm². Analysis with the equivalent circuit model shows that performance decreases as area increases because of an increasing series resistance presented by the transparent electrode. A metal grid, to provide low resistance pathways for current, fabricated on top of the transparent electrode is proposed to reduce the effective resistance. The grid is unique in that it is placed between the electrode and the semiconductor layer and must be passivated to prevent shorts through the thin semiconductor to the back metal electrode. Analysis of the grid predicts greatly reduced series resistance, and experimental results show reduced resistance and improved performance for the 7 cm² and 36.4 cm² devices when including the grid.

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Baptista, João Eduardo Ribeiro. „Análise Probabilística das Variações de Tensão de Curta Duração em Redes de Distribuição de Baixa Tensão Considerando a Inserção de Geração Distribuída Fotovoltaica“. Universidade Federal do Maranhão, 2016. http://tedebc.ufma.br:8080/jspui/handle/tede/300.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Driven by the high indices of solar irradiation in Brazil, the increasing reduction on the price of the photovoltaic solar panels and the high tariffs charged by the utility companies, the photovoltaic distributed generation (PVDG) shall considerably increase its participation percentage in the Brazilian energy matrix in the next years. Due to this tendency, it is important to know the technical impacts of the connection of PVDG to electric grid. It is known that the insertion of DG affects the short circuit levels. One of the most important power quality disturbances in sensitive loads are the short duration voltage variations (SDVV) caused mainly by short circuits (faults) in the electric network. Thus, the insertion of PVDG has the potential to affect quality indices associated with SDVV. However, the power output of the PVDG depends on the stochastic environmental conditions, i.e., the solar irradiance and the environmental temperature. Due to this, a precise assessment of the impact of PVDG on the indices associated with SDVV must be carried out considering uncertainties related to these environmental conditions. This work assessed the impact of PVDG in the SDVV indices of the secondary distribution system proposed by the CIGRÈ using a probabilistic approach. For this purpose, it was developed a model based on the following techniques: network representation in phase coordinates, admittance summation method, failure rate model based on loading condition, state enumeration method and data clustering. Uncertainties in the fault scenario (for example, fault location, type and resistance) and in the output power variation of the PVDG due to random variations of the solar irradiance and the environmental temperature were considered. The fault scenario uncertainties were modeled according to their known probability distributions, while the one related to the input parameters of the PVDG were modeled using data clustering techniques. The state enumeration method based on fault position was chosen to perform the probabilistic prediction of the SDVV indices after a careful comparison between this method and the Monte Carlo simulation method considering both precision and computational effort. The admittance summation method was used to obtain the pre-fault and the post-fault states of the network. It was proposed an improvement of this method in order to reduce the CPU time of the short-circuit states evaluation. It was also proposed a model to obtain the failure rate of a feeder section according to the loading condition of its conductors. This model intended to investigate the variation on SDVV indices due to changing in the reliability data of the feeders caused by the variation on their loading which is caused by the insertion of PVDG in the system. Tests carried on the CIGRÈ low voltage system showed that the insertion of PVDG has little direct effect in the SDVV indices, but it can significantly reduce the indices by the indirect effect of the failure rate reduction caused by the decrease in the distribution network loading.
Impulsionada pelos altos índices de irradiação solar no Brasil, pela crescente redução do preço dos painéis fotovoltaicos e pelas altas tarifas praticadas pelas concessionárias, a geração distribuída fotovoltaica (GDFV) deve aumentar consideravelmente seu percentual de participação na matriz energética brasileira dos próximos anos. Devido a esta tendência, é importante que se conheçam os impactos técnicos da conexão da GDFV à rede elétrica. Sabe-se que a inserção de GD afeta os níveis de curto-circuito. Um dos distúrbios de qualidade de energia mais impactantes em cargas sensíveis são as variações de tensão de curta-duração (VTCD), cuja principal causa são os curtos-circuitos (faltas) na rede elétrica. Desta forma, a inserção de GDFV tem potencial para afetar índices de qualidade associados com as VTCD. No entanto, a potência de saída da GDFV depende de fatores ambientais estocásticos, i.e., a irradiância solar e a temperatura ambiente. Devido a isto, uma determinação precisa do impacto da GDFV nos índices associados com VTCD deve ser realizada considerando as incertezas relacionadas a tais fatores ambientais. Este trabalho avaliou o impacto da GDFV nos índices de VTCD do sistema de distribuição secundário proposto pelo CIGRÈ a partir de um enfoque probabilístico. Para tanto, desenvolveu-se um modelo baseado nas técnicas: representação da rede em coordenadas de fase, método de soma de admitâncias, modelo de taxa de falha baseado na condição de carregamento, método de enumeração de estados e agrupamentos de dados. Foram consideras as incertezas nos cenários de falta (por exemplo, local, tipo e resistência de falta) e na potência de saída da GDFV devido às variações estocásticas na irradiância solar e na temperatura ambiente. As incertezas do cenário de faltas foram modeladas de acordo com suas distribuições de probabilidade conhecidas, enquanto as relacionadas aos parâmetros de entrada da GDFV foram modeladas utilizando-se técnicas de agrupamentos de dados. O método de enumeração de estados baseado nas posições de falta foi escolhido para efetuar a predição probabilística dos índices de VTCD, após criteriosa comparação deste com o método de simulação Monte Carlo em termos de precisão e esforço computacional. O método de soma de admitâncias foi utilizado para obtenção dos estados pré-falta e pós-falta da rede. Foi proposto um aprimoramento desse método, de forma a reduzir o tempo de execução da avaliação dos estados de curto-circuito. Também foi proposto um modelo de obtenção da taxa de falha de uma seção de alimentador de acordo com a condição de carregamento dos seus condutores. Este modelo buscou investigar a variação nos índices de VTCD resultante da alteração dos dados de confiabilidade dos alimentadores provocada pela variação no carregamento dos mesmos, causada, por sua vez, pela inserção de GDFV no sistema. Os resultados dos testes no sistema de baixa tensão do CIGRÈ mostraram que a inserção de GDFV pouco afeta os índices de VTCD de forma direta, mas pode reduzir os índices significativamente de forma indireta devido à redução das taxas de falha anuais dos alimentadores causada pela diminuição no carregamento da rede de distribuição.

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Abbas, Junaid. „Logical selectivity for medium voltage overcurrent protection and its verification via co-simulation tool for the responses of the power and communication network“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15274/.

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This thesis deals with the modelling and simulation of MV network overcurrent protection using EMTP. Transmission lines 25 Km in length for both radial and loop network with constant parameters operates at 50 Hz and 66 kV line to line voltages are simulated using EMTP. The first part of the thesis discusses the simulation of Radial network with unearthed neutral for analysing the behaviour of the fault current making the comparison with healthy feeder. Second part is to use a Radial network with compensated neutral, Petersen Coil (PC) is used for compensation of the short circuit current making the similar comparison. Third step is to design a 67N directional replay protection in EMTP to trip the circuit breaker in the fault situation. Then using both Radial and Loop network, a comparison and response of the 67N protection in both situations is analysed. Several simulations of Single Line to Ground Faults (SLGF) with different fault locations were carried out to verify the correct operation of the relay based on the developed protection scheme. The results of the simulation the operation of the relay based on its protection scheme and its response time based on the fault location. Finally, delay between the blocking signals are inserted to see the behaviour of the protection system under loop network configuration.

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15

Howard, Dustin F. „Short-circuit currents in wind-turbine generator networks“. Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50361.

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Protection of both the wind plant and the interconnecting transmission system during short-circuit faults is imperative for maintaining system structural integrity and reliability. The circuit breakers and protective relays used to protect the power system during such events are designed based upon calculations of the current that will flow in the circuit during the fault. Sequence-network models of various power-system components, such as synchronous generators, transformers, transmission lines, etc., are often used to perform these calculations. However, there are no such models widely accepted for certain types of wind-turbine generators used in modern wind plants. The problem with developing sequence-network models of wind plants is that several different wind-turbine generator designs exist; yet, each exhibit very different short-circuit behavior. Therefore, a “one size fits all” approach is not appropriate for modeling wind plants, as has been the case for conventional power plants based on synchronous-generator technology. Further, many of the newer wind-turbine designs contain proprietary controls that affect the short-circuit behavior, and wind-turbine manufacturers are often not willing to disclose these controls. Thus, protection engineers do not have a standard or other well-established model for calculating short-circuit currents in power systems with wind plants. Therefore, the research described in this dissertation involves the development of such models for calculating short-circuit currents from wind-turbine generators. The focus of this dissertation is on the four existing wind-turbine generator designs (identified as Types 1 – 4). Only AC-transmission-interconnected wind-turbine generators are considered in this dissertation. The primary objective of this research is the development of sequence-network models, which are frequency-domain analysis tools, for each wind-turbine generator design. The time-domain behavior of each wind-turbine generator is thoroughly analyzed through transient simulations, experimental tests on scaled wind-turbine generator test beds, and solutions to the system dynamic equations. These time-domain analyses are used to support the development of the sequence-network models.

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Horký, Jiljí. „Analýza stavu potrubí odvodnění parní turbíny K 220-44 a návrh korektivních opatření“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443203.

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This diploma thesis deals with the analysis of the drainage pipeline of the Škoda K 220-44 steam turbine. This turbine is operated in Dukovany Nuclear Power Plant. One part of this work is proposal of corrective measures. The aims of this work include the creation of a search for drainage, steam, erosion corrosion and mapping of defects in long-term operated drainage system. Work also includes the evaluation of measured values of the pipe wall thickness measured by ultrasonic analyzer. In addition, the work contains images created from 3D model, on which the location of defects and measurements are displayed.

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Fourie, Johannes Frederick. „Evaluation of generator circuit breaker applications / J.F. Fourie“. Thesis, North-West University, 2010. http://hdl.handle.net/10394/4220.

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The use of generator circuit breakers in power stations was investigated and evaluated. A feasibility study to determine if the additional capital cost required, when using a generator circuit breaker in a power station could be justified by the advantages it provides. The background to the study is provided through a technology and literature survey. Included in the technology review and the literature study is information on interruption mediums, the historic developments of circuit breakers and generator circuit breaker application theory. This data was used to determine the practicality of using a specific interruption medium within a generator circuit breaker application. The requirements of generator circuit breakers were determined and used to evaluate the interruption mediums in question. To ensure practical results, commonly used layouts were used to determine the effect of using a generator circuit breaker on the reliability, availability and the mean time to repair of a power station electrical distribution layout. Furthermore, the effect of the protection on the generator and generator transformer was evaluated. It was found that increased selectivity of the protection system by using a generator circuit breaker limits the extent of equipment damage in case of failure. Practical layouts were used to determine the effect on reliability. The analysis was conducted using assumed values of operational costs to determine the cost incurred through the change in reliability of the power station. By adding a generator circuit breaker, the station transformer and associated equipment is regarded as back-up or redundant equipment. This increases the reliability of the power station dramatically and limits the risk of income lost due to failures. The full evaluation included the estimation of the capital investment costs and the impact that the additional cost has on the operational requirements of a power station. The study determined that the capital cost required to use a generator circuit breaker results in no additional income for a power station. Through the increased protection, higher availability and the possible omission of power station ancillary equipment, the use of generator circuit breakers will result in more power being delivered and more income generated by a power station. The study proved that the generator circuit breaker is a critical part of a power station layout and is a necessary capital requirement to ensure the sustainability of the power station.
Thesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2010.

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Lazzari, Cristiano. „Automatic layout generation of static CMOS circuits targeting delay and power“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2003. http://hdl.handle.net/10183/5690.

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A crescente evolução das tecnologias de fabricação de circuitos integrados demanda o desenvolvimento de novas ferramentas de CAD. O desenvolvimento tradicional de circuitos digitais a nível físico baseia-se em bibliotecas de células. Estas bibliotecas de células oferecem certa previsibilidade do comportamento elétrico do projeto devido à caracterização prévia das células. Além disto,diferentes versões para cada célula são requeridas de forma que características como atraso e consumo sejam atendidos, aumentando o número de células necessárias em uma bilioteca. A geração automática de leiautes é uma alternativa cada vez mais importante para a geracão baseada em células. Este método implementa transistores e conexões de acordo com padrões que são definidos em algoritmos sem as limitações impostas pelo uso de uma biblioteca de células. A previsibilidade em leiautes gerado automaticamente é oferecida por ferramentas de análise e estimativa. Estas ferramentas devem ser aptas a trabalhar com estimativas do leiaute e gerar informações relativas a atraso, potência e área. Este trabalho inclui a pesquisa de novos métodos de síntese física e a implementação de um gerador automático de leiautes cujas células são geradas no momento da síntese do leiaute. A pesquisa investiga diferentes estratégias de disposição dos componentes (transistores, contatos e conexões) em um leiaute e seus efeitos na ocupação de área e no atraso e de um circuito. A estratégia de leiaute utilizada aplica técnicas de otimização de atraso pela integração com uma técnicas de dimensionamento de transistores. Isto é feito de forma que o método de folding permita diferentes dimensionamentos para os transistores. As principais características da estratégia proposta neste trabalho são: linhas de alimentação entre bandas, roteamento sobre o leiaute (não são utilizados canais de roteamento) e geração de leiautes visando a redução do atraso do circuito pela aplicação da técnica de dimensionamento ao leiaute e redução do comprimento médio das conexões. O fato de permitir a implementação de qualquer combinação de equações lógicas, sem as restrições impostas pelo uso de uma biblioteca de células, permite a síntese de circuitos com uma otimização do número de transistores utilizados. Isto contribui para a diminuição de atrasos e do consumo, especialmente do consumo estático em circuitos submicrônicos. Comparações entre a estratégia proposta e outros métodos conhecidos são apresentadas de forma a validar a proposta apresentada.
The evolution of integrated circuits technologies demands the development of new CAD tools. The traditional development of digital circuits at physical level is based in library of cells. These libraries of cells offer certain predictability of the electrical behavior of the design due to the previous characterization of the cells. Besides, different versions of each cell are required in such a way that delay and power consumption characteristics are taken into account, increasing the number of cells in a library. The automatic full custom layout generation is an alternative each time more important to cell based generation approaches. This strategy implements transistors and connections according patterns defined by algorithms. So, it is possible to implement any logic function avoiding the limitations of the library of cells. Tools of analysis and estimate must offer the predictability in automatic full custom layouts. These tools must be able to work with layout estimates and to generate information related to delay, power consumption and area occupation. This work includes the research of new methods of physical synthesis and the implementation of an automatic layout generation in which the cells are generated at the moment of the layout synthesis. The research investigates different strategies of elements disposition (transistors, contacts and connections) in a layout and their effects in the area occupation and circuit delay. The presented layout strategy applies delay optimization by the integration with a gate sizing technique. This is performed in such a way the folding method allows individual discrete sizing to transistors. The main characteristics of the proposed strategy are: power supply lines between rows, over the layout routing (channel routing is not used), circuit routing performed before layout generation and layout generation targeting delay reduction by the application of the sizing technique. The possibility to implement any logic function, without restrictions imposed by a library of cells, allows the circuit synthesis with optimization in the number of the transistors. This reduction in the number of transistors decreases the delay and power consumption, mainly the static power consumption in submicrometer circuits. Comparisons between the proposed strategy and other well-known methods are presented in such a way the proposed method is validated.

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Moore, Christopher Wayne. „Microfabricated Fuel Cells To Power Integrated Circuits“. Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7106.

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Microfabricated fuel cells have been designed and constructed on silicon integrated circuit wafers using many processes common in integrated circuit fabrication, including sputtering, polymer spin coating, reactive ion etching, and photolithography. Fuel delivery microchannels were made through the use of sacrificial polymers. The characteristics of different sacrificial polymers were studied to find the most suitable for this work. A polypropylene carbonate solution containing a photo-acid generator could be directly patterned with ultraviolet exposure and thermal decomposition. The material that would serve as the fuel cells proton exchange membrane (PEM) encapsulated the microchannels. Silicon dioxide deposited by plasma enhanced chemical vapor deposition (PECVD) at relatively low temperatures exhibited material properties that made it suitable as a thin-film PEM in these devices. By adding phosphorous to the silicon dioxide recipe during deposition, a phosphosilicate glass was formed that had an increased ionic conductivity. Various polymers were tested for use as the PEM or in combination with oxide to form a composite PEM. While it did not work well alone, using Nafion on top of the glass layer to form a dual-layer PEM greatly enhanced the fuel cell performance, including yield and long-term reliability. Platinum and platinum/ruthenium catalyst layers were sputter deposited. Experiments were performed to find a range of thicknesses that resulted in porous layers allowing contact between reactants, catalyst, and the PEM. When using the deposited glasses, multiple layers of catalyst could be deposited between thin layers of the electrolyte, resulting in higher catalyst loading while maintaining porosity. The current and power output were greatly improved with these additional catalyst layers.

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20

Thompson, David. „DESIGN OF EMBEDDED POWER SIGNATURE GENERATION CIRCUITS FOR INTERNET OF THINGS SECURITY“. OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2707.

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With the wide adoption of Internet of Things (IoT) in applications that involve sensitive information, the security of IoT devices is becoming an important concern. IoT devices face many challenges in securing information due to their low cost and computation constrains. To over come such challenges, different techniques have been developed. One such technique is power analysis. However, power analysis requires equipment that is often bulky, power hungry and expensive, making them unsuitable for many IoT applications. This thesis developed two energy signature capturing circuits that can be embedded into low dropout (LDO) voltage regulators. The first design targets analog LDO circuits and the second design is suitable for the newly emerged digital LDOs. Both circuits are designed and simulated using a commercial 130nm CMOS technology. To evaluate the effectiveness of the developed circuits, power traces collected from a wireless sensor device are used in circuit simulations. The results indicate that the developed circuits can detect different model wireless transmission as well as other abnormal operations.

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Besmi, Mohammad Reza. „Generator power system modelling and stabiliser design using genetic and neural methods“. Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309406.

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22

Höppner, Sebastian. „Clock Generator Circuits for Low-Power Heterogeneous Multiprocessor Systems-on-Chip“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-193156.

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In this work concepts and circuits for local clock generation in low-power heterogeneous multiprocessor systems-on-chip (MPSoCs) are researched and developed. The targeted systems feature a globally asynchronous locally synchronous (GALS) clocking architecture and advanced power management functionality, as for example fine-grained ultra-fast dynamic voltage and frequency scaling (DVFS). To enable this functionality compact clock generators with low chip area, low power consumption, wide output frequency range and the capability for ultra-fast frequency changes are required. They are to be instantiated individually per core. For this purpose compact all digital phase-locked loop (ADPLL) frequency synthesizers are developed. The bang-bang ADPLL architecture is analyzed using a numerical system model and optimized for low jitter accumulation. A 65nm CMOS ADPLL is implemented, featuring a novel active current bias circuit which compensates the supply voltage and temperature sensitivity of the digitally controlled oscillator (DCO) for reduced digital tuning effort. Additionally, a 28nm ADPLL with a new ultra-fast lock-in scheme based on single-shot phase synchronization is proposed. The core clock is generated by an open-loop method using phase-switching between multi-phase DCO clocks at a fixed frequency. This allows instantaneous core frequency changes for ultra-fast DVFS without re-locking the closed loop ADPLL. The sensitivity of the open-loop clock generator with respect to phase mismatch is analyzed analytically and a compensation technique by cross-coupled inverter buffers is proposed. The clock generators show small area (0.0097mm2 (65nm), 0.00234mm2 (28nm)), low power consumption (2.7mW (65nm), 0.64mW (28nm)) and they provide core clock frequencies from 83MHz to 666MHz which can be changed instantaneously. The jitter performance is compliant to DDR2/DDR3 memory interface specifications. Additionally, high-speed clocks for novel serial on-chip data transceivers are generated. The ADPLL circuits have been verified successfully by 3 testchip implementations. They enable efficient realization of future low-power MPSoCs with advanced power management functionality in deep-submicron CMOS technologies
In dieser Arbeit werden Konzepte und Schaltungen zur lokalen Takterzeugung in heterogenen Multiprozessorsystemen (MPSoCs) mit geringer Verlustleistung erforscht und entwickelt. Diese Systeme besitzen eine global-asynchrone lokal-synchrone Architektur sowie Funktionalität zum Power Management, wie z.B. das feingranulare, schnelle Skalieren von Spannung und Taktfrequenz (DVFS). Um diese Funktionalität zu realisieren werden kompakte Taktgeneratoren benötigt, welche eine kleine Chipfläche einnehmen, wenig Verlustleitung aufnehmen, einen weiten Bereich an Ausgangsfrequenzen erzeugen und diese sehr schnell ändern können. Sie sollen individuell pro Prozessorkern integriert werden. Dazu werden kompakte volldigitale Phasenregelkreise (ADPLLs) entwickelt, wobei eine bang-bang ADPLL Architektur numerisch modelliert und für kleine Jitterakkumulation optimiert wird. Es wird eine 65nm CMOS ADPLL implementiert, welche eine neuartige Kompensationsschlatung für den digital gesteuerten Oszillator (DCO) zur Verringerung der Sensitivität bezüglich Versorgungsspannung und Temperatur beinhaltet. Zusätzlich wird eine 28nm CMOS ADPLL mit einer neuen Technik zum schnellen Einschwingen unter Nutzung eines Phasensynchronisierers realisiert. Der Prozessortakt wird durch ein neuartiges Phasenmultiplex- und Frequenzteilerverfahren erzeugt, welches es ermöglicht die Taktfrequenz sofort zu ändern um schnelles DVFS zu realisieren. Die Sensitivität dieses Frequenzgenerators bezüglich Phasen-Mismatch wird theoretisch analysiert und durch Verwendung von kreuzgekoppelten Taktverstärkern kompensiert. Die hier entwickelten Taktgeneratoren haben eine kleine Chipfläche (0.0097mm2 (65nm), 0.00234mm2 (28nm)) und Leistungsaufnahme (2.7mW (65nm), 0.64mW (28nm)). Sie stellen Frequenzen von 83MHz bis 666MHz bereit, welche sofort geändert werden können. Die Schaltungen erfüllen die Jitterspezifikationen von DDR2/DDR3 Speicherinterfaces. Zusätzliche können schnelle Takte für neuartige serielle on-Chip Verbindungen erzeugt werden. Die ADPLL Schaltungen wurden erfolgreich in 3 Testchips erprobt. Sie ermöglichen die effiziente Realisierung von zukünftigen MPSoCs mit Power Management in modernsten CMOS Technologien

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Bladh, Johan. „Hydropower generator and power system interaction“. Doctoral thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182188.

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After decades of routine operation, the hydropower industry faces new challenges. Large-scale integration of other renewable sources of generation in the power system accentuates the role of hydropower as a regulating resource. At the same time, an extensive reinvestment programme has commenced where many old components and apparatus are being refurbished or replaced. Introduction of new technical solutions in existing power plants requires good systems knowledge and careful consideration. Important tools for research, development and analysis are suitable mathematical models, numerical simulation methods and laboratory equipment. This doctoral thesis is devoted to studies of the electromechanical interaction between hydropower units and the power system. The work encompasses development of mathematical models, empirical methods for system identification, as well as numerical and experimental studies of hydropower generator and power system interaction. Two generator modelling approaches are explored: one based on electromagnetic field theory and the finite element method, and one based on equivalent electric circuits. The finite element model is adapted for single-machine infinite-bus simulations by the addition of a network equivalent, a mechanical equation and a voltage regulator. Transient simulations using both finite element and equivalent circuit models indicate that the finite element model typically overestimates the synchronising and damping properties of the machine. Identification of model parameters is performed both numerically and experimentally. A complete set of equivalent circuit parameters is identified through finite element simulation of standard empirical test methods. Another machine model is identified experimentally through frequency response analysis. An extension to the well-known standstill frequency response (SSFR) test is explored, which involves measurement and analysis of damper winding quantities. The test is found to produce models that are suitable for transient power system analysis. Both experimental and numerical studies show that low resistance of the damper winding interpole connections are vital to achieve high attenuation of rotor angle oscillations. Hydropower generator and power system interaction is also studied experimentally during a full-scale startup test of the Nordic power system, where multiple synchronised data acquisition devices are used for measurement of both electrical and mechanical quantities. Observation of a subsynchronous power oscillation leads to an investigation of the torsional stability of hydropower units. In accordance with previous studies, hydropower units are found to be mechanically resilient to subsynchronous power oscillations. However, like any other generating unit, they are dependent on sufficient electrical and mechanical damping. Two experimentally obtained hydraulic damping coefficients for a large Francis turbine runner are presented in the thesis.

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Marinkovic, Djordje [Verfasser]. „A New Power-Processing Circuit for an Ultra-Low-Power Autonomous Sensor Node Based on a Piezoelectric Generator / Djordje Marinkovic“. Aachen : Shaker, 2012. http://d-nb.info/1069047155/34.

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25

Chen, Baifeng. „High-efficiency Transformerless PV Inverter Circuits“. Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/56686.

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With worldwide growing demand for electric energy, there has been a great interest in exploring photovoltaic (PV) sources. For the PV generation system, the power converter is the most essential part for the efficiency and function performance. In recent years, there have been quite a few new transformerless PV inverters topologies, which eliminate the traditional line frequency transformers to achieve lower cost and higher efficiency, and maintain lower leakage current as well. With an overview of the state-of-the-art transformerless PV inverters, a new inverter technology is summarized in the Chapter 2, which is named V-NPC inverter technology. Based this V-NPC technology, a family of high efficiency transformerless inverters are proposed and detailly analyzed. The experimental results demonstrate the validity of V-NPC technology and high performance of the transformerless inverters. For the lower power level transformerless inverters, most of the innovative topologies try to use super junction metal oxide semiconductor field effect transistor(MOSFET) to boost efficiency, but these MOSFET based inverter topologies suffer from one or more of these drawbacks: MOSFET failure risk from body diode reverse recovery, increased conduction losses due to more devices, or low magnetics utilization. By splitting the conventional MOSFET based phase leg with an optimized inductor, Chapter 3 proposes a novel MOSFET based phase leg configuration to minimize these drawbacks. Based on the proposed phase leg configuration, a high efficiency single-phase MOSFET transformerless inverter is presented for the PV micro-inverter applications. The PWM modulation and circuit operation principle are then described. The common mode and differential mode voltage model is then presented and analyzed for circuit design. Experimental results of a 250 W hardware prototype are shown to demonstrate the merits of the proposed MOSFET based phase-le and the proposed transformerless inverter. New codes require PV inverters to provide system regulation and service to improve the distribution system stabilization. One obvious impact on PV inverters is that they now need to have reactive power generation capability. The Chapter 4 improves the MOFET based transformerless inverter in the Chapter 3 and proposed a novel pulse width modulation (PWM) method for reactive power generation. The ground loop voltage of this inverter under the proposed PWM method is also derived with common mode and differential mode circuit analyses, which indicate that high-frequency voltage component can be minimized with symmetrical design of inductors. A 250-W inverter hardware prototype has been designed and fabricated. Steady state and transient operating conditions are tested to demonstrate the validity of improved inverter and proposed PWM method for reactive power generation, high efficiency of the inverter circuit, and the high-frequency-free ground loop voltage. Besides the high efficiency inverter circuit, the grid connection function is also the essential part of the PV system. The Chapter 5 present the overall function blocks for a grid-connected PV inverter system. The current control and voltage control loop is then analyzed, modeled, and designed. The dynamic reactive power generation is also realized in the control system. The new PLL method for the grid frequency/voltage disturbance is also realized and demonstrate the validity of the detection and protection capability for the voltage/frequency disturbance. At last, a brief conclusion is given in the Chapter 6 about each work. After that, future works on device packaging, system integration, innovation on inverter circuit, and standard compliance are discussed.
Ph. D.

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Naranjo, Rafael Ricardo Avila. „Alternatives to the use of the crowbar circuit in DFIG based wind turbines during balanced voltage dips“. Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-30122014-112624/.

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Most of the modern wind turbines are based on doubly fed induction generators (DFIG), with a back to back power converter connecting the rotor to the network. It is known that voltage dips at the stator terminals can cause overcurrents in the rotor windings, which could threaten the converter integrity. In order to protect the converter, several strategies have been proposed in technical literature, requiring in some cases the converter deactivation, which disables the control that the converter has over the power transference between the generator and the system. This last is not a desirable behavior since it can put on risk the voltage stability of the electric system. It is the aim of this dissertation to introduce and compare five of those protection strategies, through the computational simulation of their performance in case of balanced voltage dips. In order to achieve this, the electromagnetic dynamic model of the DFIG was theoretically developed, as well as the models of the strategies of interest. Subsequently, the computational model of the system was assembled in the software Matlabs Simulink to finally perform the desired simulations and its corresponding analysis.
A maioria das turbinas eólicas modernas é baseada em geradores de indução duplamente alimentados (GIDE), com um back to back conversor de energia que liga o rotor para a rede. Sabe-se que as quedas de tensão nos terminais do estator podem causar sobrecorrentes nos enrolamentos do rotor, que podem ameaçar a integridade do conversor. A fim de proteger o conversor, várias estratégias têm sido propostas na literatura técnica, exigindo, em alguns casos, a desativação do conversor, o qual desativa o controlo do conversor, que possui ao longo da transferência de energia entre o gerador e o sistema. Este último não é um comportamento desejável, uma vez que pode colocar em risco a estabilidade de tensão do sistema elétrico. É o objetivo desta dissertação apresentar e comparar cinco dessas estratégias de proteção, através da simulação computacional de seu desempenho em caso de quedas de tensão equilibrada. A fim de alcançar este objetivo, o modelo dinâmico eletromagnética do DFIG teoricamente foi desenvolvido, bem como os modelos das estratégias de interesse. Subsequentemente, o modelo computacional do sistema foi montado no software Simulink do Matlab para finalmente executar as simulações desejadas e sua análise correspondente.

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Moura, Adriano Aron Freitas de. „Novo MÃtodo e Modelos Para Estudos de Fluxo de PotÃncia e de Curto-circuito“. Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=9208.

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nÃo hÃ
Este trabalho apresenta um novo mÃtodo de fluxo de potÃncia linear o fluxo de potÃncia linear V-teta tambÃm apresenta uma nova modelagem do gerador sÃncrono para estudos de fluxo de potÃncia trifÃsico em redes de distribuiÃÃo desequilibradas radiais e uma modelagem do gerador eÃlico sÃncrono em componentes de fase para estudos de curto-circuito em sistemas de distribuiÃÃo radiais Os resultados revelam que 1) Para o fluxo de potÃncia linear V-teta Ã possÃvel o cÃlculo de forma desacoplada e linear dos fluxos de potÃncia ativa e reativa no sistema Assim os erros obtidos com o fluxo de potÃncia linear V-teta sÃo em geral menores que os erros obtidos no mÃtodo clÃssico de fluxo de potÃncia CC e espera-se que o mesmo seja usado em muitas aplicaÃÃes onde o mÃtodo clÃssico de fluxo de potÃncia CC Ã atualmente utilizado 2) Uma nova modelagem Ã proposta considerando o gerador sÃncrono diretamente conectado a rede elÃtrica Uma outra modelagem jÃ existente na literatura considerando a conexÃo do gerador atravÃs de retificador e inversor tambÃm Ã usada As duas modelagens sÃo utilizadas para a realizaÃÃo de estudos de impacto dos sistemas de excitaÃÃo dos geradores sÃncronos em sistemas de distribuiÃÃo com modelagem trifÃsica Os resultados sÃo obtidos utilizando-se o sistema IEEE-13 barras A modelagem do gerador sÃncrono em componentes de fase sob condiÃÃes desequilibradas permite: a) calcular as injeÃÃes ou consumo de potÃncias ativa/reativa de cada fase na mÃquina, b) simular o gerador sÃncrono como barra do tipo PQ e como barra do tipo PV Juntamente com esses estudos uma anÃlise inÃdita e detalhada de desequilÃbrio de tensÃo inclusive com uma demonstraÃÃo matemÃtica Ã apresentada 3) A representaÃÃo em componentes de fase do gerador eÃlico sÃncrono nos cÃlculos de faltas de sistemas de distribuiÃÃo radiais obtÃm resultados mais precisos do que o mÃtodo tradicional das componentes simÃtricas uma vez que valores de impedÃncias mÃtuas de diferentes valores podem ser considerados na anÃlise do sistema
This thesis presents a new method of linear power flow linear power flow V-theta it also presents a new model of synchronous generator for power flow studies in three phase unbalanced radial distribution networks and modeling of wind synchronous generator in phase components for studies of short-circuit in radial distribution systems The results reveal that 1) For the linear power flow V-theta is possible to calculate like a linear and uncoupled form the active and reactive power flows in the system Thus the errors obtained with the linear power flow V-theta are usually smaller than the errors obtained in classical method of DC power flow and it is expected that the linear power flow V-theta can be used in many applications where the classical method of DC power flow is currently used 2) A new model is proposed, considering the synchronous generator directly connected to the power grid Another existing literature modeling considering the connection from the generator through rectifier and inverter is also used The two modeling are used to perform impact studies of synchronous generators excitation systems for distribution systems with three-phase modeling The results are obtained using the IEEE 13 bus - test system The modeling of synchronous generator in phase components under unbalanced conditions allow: a) calculate the active / reactive power injections in each phase of the machine b) simulate the synchronous generator as PQ bus-type and as PV bustype Along with these studies an unprecedented and detailed analysis of voltage unbalance including a mathematical proof is presented 3) the representation of synchronous windmill generators in phase components calculations in short-circuits of radial distribution systems get more accurate results than the traditional method of symmetrical components since values of mutual impedances of different values can be considered in the analysis of the system

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Zafar, Jawwad. „Winding short-circuit fault modelling and detection in doubly-fed induction generator based wind turbine systems“. Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209854.

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Abstract

This thesis deals with the operation of and winding short-circuit fault detection in a Doubly-Fed Induction Generator (DFIG) based Wind Turbine Generator System (WTGS). Both the faulted and faultless condition of operation has been studied, where the focus is on the electrical part of the system. The modelled electrical system is first simulated and the developed control system is then validated on a test bench. The test-bench component dimensioning is also discussed.

The faultless condition deals with the start-up and power production mode of operation. Control design based on the Proportional Integral (PI) control technique has been compared for power and torque control strategies against the Linear Quadratic Gaussian (LQG) control technique, at different operating points through the variable-speed region of WTGS operation following the maximum power curve of the system. It was found that the torque control strategy offered less degradation in performance for both the control techniques at operating points different for the one for which the control system was tuned. The start-up procedure of the DFIG based WTGS has been clarified and simplified. The phase difference between the stator and the grid voltage, which occurs due to the arbitrary rotor position when the rotor current control is activated, is minimized by using a sample-and-hold technique which eliminates the requirement of designing an additional controller. This method has been validated both in simulation and experiments.

The faulted condition of operation deals with the turn-turn short-circuit fault in the phase winding of the generator. The model of the generator, implemented using the winding-function approach, allows the fault to be created online both in a stator and a rotor phase. It has been demonstrated that the magnitude of the current harmonics, used extensively in literature for the Machine Current Signature Analysis (MCSA) technique for winding short-circuit fault detection, is very different when the location of the fault is changed to another coil within the phase winding. This makes the decision on the threshold selection for alarm generation difficult. Furthermore, the control system attenuates the current harmonics by an order of magnitude. This attenuation property is also demonstrated through experiments. The attention is then shifted to the negative-sequence current component, resulting from the winding unbalance, as a possible fault residual. Its suitability is tested in the presence of noise for scenarios with different fault locations, fault severity in terms of the number of shorted-turns and grid voltage unbalance. It is found that due to the presence of a control system the magnitude of the negative-sequence current, resulting from the fault, remains almost the same for all fault locations and fault severity. Thus, it was deemed more suitable as a fault residual. In order to obtain a fast detection method, the Cumulative Sum (CUSUM) algorithm was used. The test function is compared against a threshold, determined on the basis of expected residual magnitude and the time selected for detection, to generate an alarm. The validation is carried out with noise characteristics different from the ones used during the design and it is shown that the voltage unbalance alone is not able to trigger a false alarm. In all the scenarios considered, the detection was achieved within 40 ms despite the presence of measurement filters.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

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Iindombo, Julia Dimbulukweni. „Efficiency plan for large interconnected urban ring main network under contingency conditions“. Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1185.

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Thesis (MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2011
In a situation, where there is a shortage of power generation or the power stations are operating with a very low reserve margin, as is typically the current position in South Africa, there is a need to operate distribution network at the highest possible efficiency by utilising network power loss reduction techniques. Such techniques are especially important when contingencies occur as they tend to increase loss, reduce efficiencies and cause power supplies to such networks to increase. This increase can cause the network or multiples of such networks to be load shed as the power stations do not have the reserve margins to meet this increased demand. The ideal situation would thus be to minimise network loss and in so doing decrease the amount of power needed and possibly avoid load shedding. Thus, there is a need to study efficiency, network loss reduction under contingency conditions and this is the focus of the research. Most large urban distribution networks are operated as ring main networks. Ring networks are considered to have less power loss. However, a major component in a ring network can cause the loss to substantially increase; resulting in power shortage in the network. There is an urgency to eliminate high network loss. An efficiency plan was developed for a large ring network that reduces the loss so that its input power can be decreased. In this way, the available power existing due to the contingency can be more evenly spread, and the number of ring main networks to be load shed could be reduced.

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Chamas, Ibrahim. „The Analysis and Design of Phase-tunable Low-Power Low-Phase-Noise I/Q Signal Sources for Analog Phase Calibrated Transceivers“. Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/102076.

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Due to the demand for low-cost, small-form factor and large-scale integration of system-on-chip wireless transceivers, the image-reject, zero-IF and low-IF receiver architectures have become the main topologies used in mainstream wireless communication systems. Consequently, signal sources with quadrature phase outputs [quadrature oscillators (QOs)] are therefore essential, and their phase noise, driving capability, tuning range, oscillation frequency, and power consumption have a major impact on the overall receiver performance. Additionally, it is required that the QO synthesize precise I/Q waveforms across the signal bandwidth over process, voltage, and temperature variations for adequate image-rejection and signal modulation/demodulation. While the use of symmetrical layout and large inter-digitated devices minimize both systematic and random mismatches, this solution alone may not succeed in achieving the stringent performance requirements dictated by modern wireless standards particularly as the technology scales into the sub-100nm regime, necessitating both phase and gain calibration of the mismatched I/Q channels post-fabrication. Given the necessity for precise RF quadrature signal synthesis, the goal of this work is to investigate low-power low-phase-noise quadrature oscillator (QVCO) topologies with an integrated phase calibration feature. The first part of this work focuses on the analysis and modeling of cross-coupled LC QVCOs. The analysis focuses on understanding the oscillator basic performance characteristics, design trade-offs, phase-noise performance, effect of including phase shift in the coupling paths, and on examining the quadrature accuracy in presence of process variations. New design parameters and circuit insight are developed and a generalized first order linear model and a one-port model are proposed. Particularly, we introduce the concept of an effective core and coupling transconductances to explain various oscillator properties. Additionally, a new incremental circuit element — the quadrature resistance — is introduced to evaluate the effect of coupling on the open-loop quality factor and hence on the oscillator phase noise performance. Mechanisms affecting the mode selectivity are identified and modeled. A qualitative and quantitative study of the effect of mismatch on the phase imbalance and amplitude error is presented. Particularly, closed-form intuitive expressions of the phase imbalance and amplitude error are derived and verified via circuit simulation. Based on our understanding of the various mechanisms affecting the quadrature accuracy, the second part of this work introduces a very efficient quadrature phase calibration technique based on the disconnected-source parallel-coupled LC QVCO topology. The phase-tunable LC QVCO (PT-QVCO) achieves an ultra-wide I/Q phase tuning range without affecting the relative amplitude error or consuming additional power or chip area. Additionally, in restoring the phase balance, it is observed that the proposed method restores the phase noise performance to its optimal value which presents a potential advantage over classical calibration techniques. Time domain measurements performed on a 5 GHz prototype show that I/Q signals with phase error up to ~±30°, beyond which the VCO cores are unlocked, can be driven to perfect quadrature phase. The PT-QVCO can be tuned from 3.87-4.45 GHz at the negative mode and 4.4-5.4 GHz at the positive mode, a total of ~1.5 GHz. The fabricated circuit including pad structures occupies an area of 1.1x0.7 mm² and drains 18mW (excluding buffer circuits) from a 1.8 V supply voltage. The third part of this work introduces a new low-power, low-phase-noise super harmonic injection-coupled LC QVCO (IC-QVCO) topology. Analysis of the waveform accuracy reveals an inverse dependence of the quadrature error on the tank quality factor thus allowing circuit optimization for both low phase noise and precise quadrature synthesis. Additionally, a tunable tail filter (TTF) is incorporated to calibrate the residual quadrature imbalance in presence of a 3-σ variation in the device parameters. An X-band IC-QVCO prototype with a TTF implemented in a 0.18μm RF CMOS process, achieves a measured phase noise figure-of-merit ranging from 177.3 to 182.6 dBc/Hz along the 9.0 to 9.6 GHz frequency tuning range while dissipating only 9mW from the 1.8V supply. The TTF reduces both the 1/f² and 1/f³ phase noise and calibrates the residual phase error within ±11° post-fabrication without affecting the relative amplitude error or the phase noise performance. The circuit performance compares favorably with recently published work. In the fourth part of this work, we explore the implementation of LC QVCOs as potential I/Q sources at millimeter-wave (MMW) frequencies. Among the several design challenges that emerge as the oscillator frequency is scaled into the MMW band, precise quadrature synthesis and adequate frequency tuning range are among the hardest to achieve. After describing the limitation of using an MOS varactor and a digitally controlled switch capacitor array for frequency tuning, we propose an alternative frequency tuning technique based on the fundamental operation of LC QVCOs. The off-resonance operation, which is defined by the coupling network, suggests varying the coupling current to achieve frequency tuning. In essence, by modifying the bias current of the coupling transistors (G_Mc-tuning), a wide and linear frequency tuning range can be achieved. Extensive simulation results of a 60 GHz prototype, implemented in a 90 nm commercial RF CMOS process, demonstrates a 5 GHz of frequency tuning range (57.5 GHz → 62.5 GHz), a tuning sensitivity of 1GHz/mA, and a 4dB improvement in the phase noise compared to a varactor solution. Finally, the Appendix includes recent research work on the analysis and design of gm-boosted common-gate low-noise amplifiers (CG-LNAs). While this topic seems to diverge from the main theme of the dissertation, we believe that the comprehensive analysis and the originality of the circuit design introduced in this work are worth acknowledging.
Ph.D.
While resting in bed due to illness, the Dutch scientist Christiaan Huygens keenly observed that the pendulums of two clocks hanging on the wall moved synchronously when the clocks were hung close to each other. He concluded that these two oscillatory systems were forced to move in unison by virtue of mechanical coupling through the wall. In essence, each pendulum injected mechanical vibrations into the wall that was strong enough to lock the adjacent pendulum into synchronous motion. Injection locking of oscillatory systems plays a critical role in communication systems ranging from frequency division, to generating clocks (oscillators) with finer phase separation, to the synthesis of orthogonal (quadrature) clocks. All communication systems have the same basic form. Firstly, there will some type of an information or data source which can be a keyboard or a microphone in a smartphone. The source is connected to a receiver by some sort of a channel. In wireless systems, the channel is the air medium. Moreover, to comply with the FCC and 3GPP requirements, data can only be transmitted wirelessly within a predefined set of frequencies and with stringent emission requirements to avoid interference with other wireless systems. These frequencies are generated by high fidelity clock sources, also known as oscillators. Consider a group of people sharing the same room and hence the same channel want to share information. Without regulating the “loudness” of each communicating ensemble, the quality of communication can be severely impaired. Moreover, it is to be expected that information can be shared more efficiently if each pair is allocated non-overlapping timeslots – speak when others are quiet. Called time orthogonality, all wireless systems require precise orthogonal (quadrature) clock sources to improve the communication efficiency. The precision of quadrature clocks is determined by the amplitude and phase accuracy. This dissertation takes a deep dive into the analysis and implementation of high accuracy quadrature (I/Q) clock sources using the concept of injection locking. These I/Q clocks or oscillators, also known as quadrature voltage controlled oscillators (QVCOs), have gained enormous popularity in the last decade. The first part of this work focuses on the analysis and modeling of QVCOs. The analysis focuses on understanding the oscillator basic performance characteristics, and on examining the quadrature accuracy in presence of process variations. New design parameters and circuit insight are developed and a generalized first order linear model and a one-port model are proposed. A qualitative and quantitative study of the effect of mismatch on the phase imbalance and amplitude error is presented. Particularly, closed-form intuitive expressions of the phase imbalance and amplitude error are derived and verified via circuit simulation. Based on our understanding of the various mechanisms affecting the quadrature accuracy, the second part of this work introduces a very efficient quadrature phase calibration technique based The phase-tunable QVCO (PT-QVCO) achieves an ultra-wide I/Q phase tuning range without affecting the oscillator other performance metrics. The proposed topology was successfully verified in silicon using a 5GHz prototype. The third part of this work introduces a new low-power, low-phase-noise injection coupled QVCO (IC-QVCO) topology. An X-band IC-QVCO prototype was successfully verified in a 0.18m RF CMOS process. In the fourth part of this work, we explore the implementation of QVCOs as potential I/Q sources at millimeter-wave (MMW) frequencies. Among the several design challenges that emerge as the oscillator frequency is scaled into the MMW band, precise quadrature synthesis and adequate frequency tuning range are among the hardest to achieve. After describing the limitation of using an conventional frequency tuning techniques, we propose an alternative approach based on the fundamental operation of QVCOs that outperforms existing solutions.

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Brdečko, Aleš. „Popis zkratovny CVVOZE“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220946.

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This diploma thesis deals with the analysis and description of high power laboratory CVVOZE. In the text we can find a description of the individual elements high power laboratory stating their parameters and their analysis from the perspective of impedance. The practical concern of this work is the creation of program for calculating the adjustment burdens and creating utilities helpful for operation and interpretation of laboratory function laity and technical employees.

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Säll, Erik. „Design of a Low Power, High Performance Track-and-Hold Circuit in a 0.18µm CMOS Technology“. Thesis, Linköping University, Department of Electrical Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1353.

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This master thesis describes the design of a track-and-hold (T&H) circuit with 10bit resolution, 80MS/s and 30MHz bandwidth. It is designed in a 0.18µm CMOS process with a supply voltage of 1.8 Volt. The circuit is supposed to work together with a 10bit pipelined analog to digital converter.

A switched capacitor topology is used for the T&H circuit and the amplifier is a folded cascode OTA with regulated cascode. The switches used are of transmission gate type.

The thesis presents the design decisions, design phase and the theory needed to understand the design decisions and the considerations in the design phase.

The results are based on circuit level SPICE simulations in Cadence with foundry provided BSIM3 transistor models. They show that the circuit has 10bit resolution and 7.6mW power consumption, for the worst-case frequency of 30MHz. The requirements on the dynamic performance are all fulfilled, most of them with large margins.

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Normand, Guy. „Les circuits translineaires : contribution a leur etude et a leur mise en oeuvre dans les domaines analogique et logique“. Nantes, 1987. http://www.theses.fr/1987NANT2056.

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Les circuits translineaires sont des circuits constitues d'un certain nombre de jonctions bipolaires, organisees en mailles translineaires. Le processus translineaires conduit a la realisation de nombreuses fonctions electroniques lineaires ou non lineaires, analogiques ou logiques. Les structures translineaires sont destinees a commander electroniquement le facteur transfert des reseaux lineaires

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Höppner, Sebastian [Verfasser], René [Akademischer Betreuer] Schüffny und Ulrich [Akademischer Betreuer] Rückert. „Clock Generator Circuits for Low-Power Heterogeneous Multiprocessor Systems-on-Chip / Sebastian Höppner. Betreuer: René Schüffny. Gutachter: René Schüffny ; Ulrich Rückert“. Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://d-nb.info/1093412240/34.

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Singh, Rahul. „Design Techniques for Frequency Reconfigurability in Multi-Standard RF Transceivers“. Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1185.

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Compared to current single-standard radio solutions, multi-standard radio transceivers enable higher integration, backward compatibility and save power, area and cost. The primary bottleneck in their realization is the development of high-performance frequency-reconfigurable RF circuits. To that end, this research introduces several CMOS-integrated, transformer-based reconfigurable circuit techniques whose effectiveness is validated through measurements of designed transceiver front-end low-noise (LNA) and power amplifier (PA) prototypes. In the first part, the use of high figure-of-merit phase-change (PC) based RF switches in the reconfiguration of CMOS LNAs in the receiver front-end is proposed. The first reported demonstration of an integrated, PC-switch based, dual-band (3/5 GHz) reconfigurable CMOS LNA with transformer source degeneration and designed in a 0.13 μm process is presented. In the second part, a frequency-reconfigurable CMOS transformer combiner is introduced that can be reconfigured to have similar efficiencies at widely separated frequency bands. A 65-nm CMOS triple-band (2.5/3/3.5 GHz) PA employing the reconfigurable combiner was designed. In the final part of this work, the use of transformer coupled-resonators in mm-wave LNA designs for 28 GHz bands was investigated. To cover contiguous and/or widely-separated narrowband channels of the emerging 5G standards, a 65-nm CMOS 24.9-32.7 GHz wideband multi-mode LNA using one-port transformer coupled-resonators was designed. Finally, a 25.1-27.6 GHz tunable-narrowband digitally-calibrated merged LNA-vector modulator design employing transformer coupled-resonators is presented that proposes a compact, differential quadrature generation scheme for phased-array architectures.

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Song, Tae Joong. „A fully integrated SRAM-based CMOS arbitrary waveform generator for analog signal processing“. Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34760.

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This dissertation focuses on design and implementation of a fully-integrated SRAM-based arbitrary waveform generator for analog signal processing applications in a CMOS technology. The dissertation consists of two parts: Firstly, a fully-integrated arbitrary waveform generator for a multi-resolution spectrum sensing of a cognitive radio applications, and an analog matched-filter for a radar application and secondly, low-power techniques for an arbitrary waveform generator. The fully-integrated low-power AWG is implemented and measured in a 0.18-¥ìm CMOS technology. Theoretical analysis is performed, and the perspective implementation issues are mentioned comparing the measurement results. Moreover, the low-power techniques of SRAM are addressed for the analog signal processing: Self-deactivated data-transition bit scheme, diode-connected low-swing signaling scheme with a short-current reduction buffer, and charge-recycling with a push-pull level converter for power reduction of asynchronous design. Especially, the robust latch-type sense amplifier using an adaptive-latch resistance and fully-gated ground 10T-SRAM bitcell in a 45-nm SOI technology would be used as a technique to overcome the challenges in the upcoming deep-submicron technologies.

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Guliš, Tomáš. „Zkratový výpočet a nastavení ochran generátorů vodní elektrárny Lipno I“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316972.

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This Master 's thesis deals with the topic of protection of generators in case of faults, short circuits and their calculation according to the valid standard ČSN EN 60909-0 ed.2. The practical part includes the calculation of the minimum and maximum short-circuit currents of the Lipno I hydroelectric power plant at various locations using the NetCalc calculation program and for comparison of program funcionality provides the manual calculation. Next chapter deals with the calculation of settings of each protection function of the SIEMENS Siprotec 7UM622 protection relay, which is used to protect main generators of this hydropower plant.

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Urbánek, Jaroslav. „Projekt modelu malé vodní elektrárny“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221347.

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Master thesis consists of the construction of a small hydroelectric power play model for laboratory use. The first step is to calculate parameters required for the creation of the 2D model Banki turbine. Next part is a proposal and selection of individual components of the model, such as generator, turbine housing, water circuit, pump and alternator mounting. The last step is to launch the model and verify, if the model of a small hydroelectric power plant achieves the required parameters.

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Arroyo, Emmanuelle. „Récupération d'énergie à partir des vibrations ambiantes : dispositif électromagnétique et circuit électronique d'extraction synchrone“. Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00768218.

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La récupération d'énergie vise à réaliser des dispositifs électromécaniques de taille centimétrique permettant d'alimenter des systèmes électroniques en puisant de manière opportuniste l'énergie du milieu environnant. Parmi les différentes sources disponibles (solaire,thermique etc.) les vibrations ambiantes sont susceptibles de fournir assez de puissance pour alimenter des microsystèmes autonomes tels que des noeuds de réseaux de capteurs communicants. L'enjeu consiste à concevoir des microgénérateurs effectuant la conversion de cette énergie mécanique ambiante en énergie électrique exploitable de manière optimale.Ces travaux de thèse proposent dans un premier temps un critère d'étude et de comparaison des performances des générateurs de types piézoélectriques ou électromagnétiques, à partir d'un modèle normalisé unifié. Dans un second temps, un circuit non linéaire d'extraction de l'énergie est étudié pour les générateurs électromagnétiques, et ses performances sont discutées en comparaison avec un circuit classique d'extraction de l'énergie. A partir de ces résultats, une nouvelle structure de générateur électromagnétique est conçue, optimisée puis validée expérimentalement.

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Halaš, Rostislav. „Odstraňovač zubního kamene“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219252.

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Tato práce se zabývá návrhem ultrazvukového odstraňovače zubního kamene pracujícím na frekvenci 27 kHz s maximální intenzitou ultrazvuku 5W/cm2. Popisuje mechanismus vzniku zubního kamene, důsledky na zdraví a metody jeho odstraňování. Zaměřuje se na principy odstraňování s využitím ultrazvukového vlnění. Dále je sestaveno funkční a blokové schéma. Na základě těchto znalostí je proveden návrh a výpočet jednotlivých částí aplikátoru. Výkonové a napěťové poměry jsou vypočítány od aplikačního hrotu směrem ke generátoru. V neposlední řadě je popsán návrh obvodů buzení měniče i kontrolních obvodů. Schémata jsou doplněna výkresy desek plošných spojů a soupiskou součástek.

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Černý, Michal. „Analýza sekundárního okruhu bloku VVER 440“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378709.

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The main aim of this thesis is the model design and control the secondary circuit block VVER 440. The search part of my work is a description of the secondary circuit. In the first part of the calculation is performed for the rated secondary circuit. The second calculation part focuses on the calculation circuit of the secondary for the reduced, influenced by shutting down one steam generator.

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Petrič, Peter. „Návrh uzemňovače 80 kA/3 s pro odpojovač generátoru“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-376995.

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This master thesis is focused on the design of earthing switch for the indoor three pole generator disconnector from IVEP, a.s. The main task of the theoretical part of the master thesis was mechanical and electrical calculations on the contact system and the design of two variants of earthing switch construction. It has been proposed two variants of earthing switch construction. The first variant included three earthing knives for each pole of earthing switch and the other variant included two earthing knives for each pole. The aim of the practical part of this diploma thesis was to create a model of the earthing switch for generator disconnector, to simulate the heating of the contact system by passing the short-circuit current and to prepare the production documentation. For modeling, calculations and simulations were used Autodesk Inventor 2018, Matlab and Ansys Workbench.

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Sýkora, Martin. „Studie připojitelnosti výrobny“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219019.

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It is necessary to judge the influences of producers on the electric compounds while creating electrical energy or during the regulation of those existing. These analyses are sorted out by so called studies of connectivity. These calculations analyze the degree of connection of the producer and the standby unit during a break-down. The results of this report are several recommendations for creating such unit and succeeding steps leading to secure the stability and safety of the electric compound operation. The aim of this thesis is to discuss about software for PC solutions for static and dynamic network model, to draft power outlet into a network of generating high voltage, to complete a study of connectivity with respect to all the distortion factor, as increased voltage, inrush current at startup, flicker, harmonic currents, interference ripple, contribution to short-circuit current, reactive power control options, and demands for compensation.

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Huang, Kuei-Ming, und 黃奎銘. „Research on Power Transformation Circuit of Wind Power Generation System“. Thesis, 2017. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22105CYCU5489070%22.&searchmode=basic.

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碩士
中原大學
機械工程研究所
105
In this paper, we design a wind power generation system to convert the AC voltage output from the wind turbine through the full bridge rectification change from AC to DC voltage in the wind turbine. Due to the fact that the wind power generation varies with the difference of the wind speed that produce unstable AC voltage. This paper use of DC / DC converter through the rectifier with the difference of the wind turbine generator output to produce a different DC voltage into a sufficient battery charge voltage. At the same time, DC / DC converters charge the battery and transmit energy to the inverter, converting the resulting DC voltage to an AC voltage of 220V during the windless state. As a result, the energy stored in the battery can be temporarily used as an alternative power source to provide an inverter reach into AC power uninterruptible power system. In order to make the wind turbine at lower wind speed Voltage that can also charge the battery. Therefore the battery need to increase the DC / DC converter input voltage range. In this paper we use two different specifications of the DC / DC converter, then through the input voltage range of the expansion combination of the two diodes to make the range of acceptable wind speeds becomes wider.

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CHEN, SHIH-SYUN, und 陳世勳. „The develop a step up circuit of TB88 IC in thermal power generation“. Thesis, 2017. http://ndltd.ncl.edu.tw/handle/qsq8e4.

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碩士
國立宜蘭大學
機械與機電工程學系碩士班
105
In this study, the TB-88 set-up subjected to thermoelectric chip, TEG112703. Here both side of thermoelectric chip was heat imposed under the differential surficial temperature, it is investigated several hundred millivolts of voltage. The power seems too be still weak to meet the commercial development. It was still available to be practical after invoking the circuit module. Consequently a TB-88 IC step up circuit, thermoelectric electricity transforming efficiency 55~65 % has been carried out, which successfully boosts the voltage from 0.5 V to 5 V. And the self-designed device significantly reduces the experimental budget. Besides, the TB-88 thermoelectric system will induce 79.8 mW of 2.85 V and 28 mA during the initial 3 minutes, which delivers additional benefit, about 53 % of power as well as half of start-up time, while compared to the performance undertaken by original design. Base on above advantage accessed, the extended TB-88 set-up module for the future research might be believed to be beneficent to the development of green energy.

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Figarado, Sheron. „Multilevel Inverter Topologies With Reduced Power Circuit Complexity For Medium Voltage High Power Induction Motor Drives By Cascading Conventional Two-Level And Three-Level Inveters“. Thesis, 2009. http://hdl.handle.net/2005/1061.

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Multilevel inverters have advantages over two-level inverters such as reduced THD, ability to operate at low switching frequencies, reduced switching losses etc. Moreover, higher voltage levels can be handled with devices of lower voltage rating. The main disadvantage with the multilevel configurations compared to the two-level inverter configuration is the increase in the number of power devices required and the circuit complexity, which necessitates complex control schemes that add to the cost. Also, the reliability of the converters comes down as the number of devices increases. Reduction in complexity and modularity are desirable characteristics for the multilevel inverters. Open-end winding Induction Motor (IM) drive configurations are shown to have advantages over the motor drive schemes with isolated neutral. The DC-link requirement in case of open-end winding structures comes down to half the voltage rating of the conventional NPC inverters. The DC- link requirement in case of open-end winding structures comes down to half compared to that of the conventional NPC inverters. The number of switching states is higher in the case of open-end winding configuration compared to multiplicity of switching states of conventional NPC inverters, which gives a control flexibility that can be used for optimizing the hardware requirements. Taking advantage of the flexibility given by open-end winding configuration, this thesis proposes schemes which have reduced power circuit complexity. Non-sinusoidal voltage fed IM drives suffer from the problems related to the common mode voltage (CMV) generated by the inverters. This CMV causes bearing currents and shaft voltages which in turn cause increased conducted EMI, ground loop currents and premature bearing failure. A three-level scheme was proposed for an open-end winding Induction machine in the literature, which completely eliminate the CMV variation from the pole voltages as well as the phase voltages. This configuration uses 24 controlled switches and two isolated DC-sources. In this thesis, three-level inverter schemes with CMV elimination and reduced power device count for an open-end winding IM drive are proposed. The first scheme gets the reduction in switch count by sharing the top inverter of the three-level scheme and the second scheme achieves the same by sharing the bottom inverter. This way, the number of controlled switches comes down to 18 from 24. Another problem with multilevel inverters is the large number of isolated DC-sources required to achieve the multilevel inversion. Reducing the number of isolated supplies and using capacitors to split the voltage levels poses the problem of capacitor voltage balancing. A four-level inverter with both CMV elimination and capacitor voltage balancing for an open-end winding IM drive is proposed in this thesis. The motor is fed by two four-level inverters from both the sides. A closed loop capacitor voltage balancing scheme is implemented and the redundancies in the switching states are used for achieving the capacitor voltage balancing and thereby reducing the total number of DC-link to two. The control scheme is independent of the load power factor and maintains the balance in the entire modulation range. A five-level inverter scheme is proposed for an open-end winding IM drive in this thesis. It requires only two isolated DC-sources to achieve the five-level inversion. The motor is fed by one NPC three-level inverter from one side and a two-level inverter from the other. The inverters on either side share the DC-sources. Common mode voltage in the phases are made zero in an average sense using sine-triangle modulation in the proposed scheme so that the common mode currents through the phases are suppressed. The maximum fundamental voltage that can be obtained at the phase is limited to 0.5Vdc. DC-link requirement of the inverter scheme is half of that of conventional five-level inverter scheme because of the open-end winding structure. The two-level inverter, which should withstand half the DC-link voltage, is always in square wave operation and hence the switching losses are very less. All the schemes are simulated extensively in MATLAB/Simulink and experimentally verified on laboratory prototypes under V/f control. TI Motor control DSP and Xilinx CPLD/FPGA are used for generation of the PWM signals for the schemes. The inverters are switched at around 1.25 kHz to keep the switching losses low. Due to laboratory constraints, the experimental verification is done on low power prototypes. Nonetheless, the generality of the schemes allow them to be used for medium voltage high power applications.

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„Development of a PCB-integrated micro power generator“. 2001. http://library.cuhk.edu.hk/record=b5895873.

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Ching Ngai-hung.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.
Includes bibliographical references (leaves 81-83).
Abstracts in English and Chinese.
Chapter CHAPTER 1 ´ؤ --- INTRODUCTION --- p.1
Chapter 1.1 --- Background on Micro Power Supply --- p.1
Chapter 1.2 --- Literature Survey --- p.3
Chapter 1.2.1 --- Comparison Among Different Power Sources & Transduction Mechanisms --- p.3
Chapter 1.2.2 --- Previous Works in Vibration Based Generator --- p.6
Chapter CHAPTER 2 一 --- DESIGN OF THE MICRO-POWER GENERATOR --- p.8
Chapter 2.1 --- Concept of Power Generation --- p.8
Chapter 2.2 --- Design Objectives of the Micro Power Generation --- p.9
Chapter 2.3 --- System Modelling and Configuration of the Generator --- p.10
Chapter 2.4 --- RESONATING STRUCTURE --- p.13
Chapter 2.4.1 --- Material Selection --- p.13
Chapter 2.4.2 --- Fabrication Method --- p.14
Chapter CHAPTER 3 一 --- INDUCTING STRUCTURE --- p.17
Chapter 3.1 --- Selection of Winding Method --- p.17
Chapter 3.2 --- Solenoid Windings --- p.19
Chapter 3.2.1 --- Fabrication Process --- p.19
Chapter 3.3 --- PCB Windings --- p.20
Chapter 3.3.1 --- Fabrication Process of the Prototype of Six-layer PCB --- p.21
Chapter CHAPTER 4 一 --- EXPERIMENTAL RESULTS --- p.27
Chapter 4.1 --- Experimental Setup --- p.27
Chapter 4.1.1 --- Generator Systems --- p.27
Chapter 4.1.2 --- Measurement of Vibration and Output from the Generator --- p.28
Chapter 4.1.3 --- Observations of Vibration Motions --- p.31
Chapter 4.2 --- SPRING FOR THE MICRO GENERATOR --- p.32
Chapter 4.2.1 --- Spring Micromachining Optimization --- p.32
Chapter 4.2.2 --- Mode Shapes and Spiral-spring Structures --- p.35
Chapter 4.3 --- MAGNET FOR THE MICRO GENEARTOR --- p.37
Chapter 4.3.1 --- Generator Output and Magnetic Dipole Orientation --- p.37
Chapter 4.4 --- HAND-WIRED COIL GENEARTOR --- p.45
Chapter 4.4.1 --- Performance of Different Design of Housings --- p.45
Chapter 4.5 --- PCB COIL GENERATOR --- p.48
Chapter 4.5.1 --- Size of PCB Coils vs. Generator Output --- p.48
Chapter 4.5.2 --- Effect of Number of PCB Layers --- p.54
Chapter 4.5.3 --- Array of Generators --- p.61
Chapter CHAPTER 5 一 --- MODELLING AND COMPUTER SIMULATION --- p.63
Chapter 5.1 --- Modelling the Second-Order System --- p.63
Chapter CHAPTER 6 一 --- APPLICATION DEMONSTRATIONS --- p.69
Chapter 6.1 --- INFRARED SIGNAL TRANSMISSION --- p.69
Chapter 6.2 --- RF WIRELESS TEMPERATURE SENSING SYSTEM --- p.70
Chapter CHAPTER 7 ´ؤ --- CONCLUSION --- p.75
Chapter CHAPTER 8 一 --- FUTURE WORK --- p.77
BIBLIOGRAPHY --- p.81
APPENDIX --- p.84

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(8848484), Arturo Garcia. „EXPERIMENT AND MODELING OF COPPER INDIUM GALLIUM DISELENIDE (CIGS) SOLAR CELL: EFFECT OF AXIAL LOADING AND ROLLING“. Thesis, 2020.

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In this paper various applications of axial tensile load, bending load, and rolling loading has been applied to a Copper Indium Gallium Diselenide (CIGS) Solar Cell to lean how it would affect the solar cell parameters of: Open circuit voltage (Voc), Short circuit current, (Isc), Maximum power (Pmax), and Efficiency (EFF), and Fill Factor (FF). These Relationships were found for with three different experiments. The first experiment the applies axial tensile stress is to a CIGS solar cell ranging from 0 to 200 psi with various strain rates: 0.0001, 0.001, 0.01, and 0.1 in/sec as well as various relaxation time: 1min, 5min, and 10 min while the performance of solar cell is measured. The results of this gave several trends couple pertaining the Voc . The first is that open circuit voltage increases slightly with increasing stress. The second is the rate of increase (the slope) increases with longer relaxation times. The second set of trend pertains to the Isc. The first is that short circuit current generally is larger with larger stress. The second is there seems to be a general increase in the Isc up to a given threshold of stress. After that threshold the Isc seems to decrease. The threshold stress varies depending on strain rate and relaxation time. The second set of experiments consisted of holding a CIGS solar cell in a fixed curved position while it was in operational use. The radii of the curved cells were: 0.41, 0.20, 0.16, 0.13, 0.11, 0.094, and 0.082 m. The radii were performed for both concave and convex cell curvature. The trends for this show a slight decrease in all cell parameters with decreasing radii, the exception being Voc which is not effecting, the convex curvature causing a slightly faster decrease than the concave. This set of experiments were also processed to find the trends of the single diode model parameters of series resistance (Rs), shunt resistance (Rsh), dark current (I0), and saturation current (IL), which agreed with the experimental results. The second experiment consisted of rolling a CIGS solar cell in tensile (cells towards dowel.) and compression (cells away from dowel) around a dowel to create internal damage. The diameter of the dowels decreased. The dowel diameters were: 2. 1.75, 1.25, 1, 0.75, 0.5, and 0.25 inches. This experiment showed similar trends as the bending one but also had a critical diameter of 1.75 in where beyond that damage much greater. Finally a parametric study was done in COMSOL Multiphysics® to examine how changes in the CIGS material properties of electron mobility (EM), electron life time, (EL), hole mobility 15 (HM), and Hole life time (HL) effect the cell parameters. The trends are of an exponential manner that converges to a given value as the material properties increase. When EL, EM, HL are very small, on the order of 10-4 times smaller than their accepted values, a transient like responses occurs.

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Leong, Yoke Choy. „Broadband millimeter wave power generation using integrated circuits“. 2000. https://scholarworks.umass.edu/dissertations/AAI9988814.

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Broadband, millimeter-wave signals can be generated by using frequency multipliers that are cascaded by broadband power amplifier at the output. This approach has the potential to generate an electronically tunable signal with adequate output power over a wide range of frequencies. In this work, important issues including device modeling, broadband amplifier design and frequency tripler design are investigated. New equations for modeling the drain current, the gate-source and the gate-drain capacitances for HEMT have been proposed. The parameters of the proposed drain current model can be extracted directly and the parameters of the capacitance models can be estimated directly. This results in a fast and efficient parameter extraction process. The new capacitance models ensure that the nonlinear model is consistent with the common small-signal equivalent circuit model along a resistive load line in the IV plane. Since the common small-signal equivalent circuit model has been successfully used in MMIC designs up to 200 GHz, consistency between the models will ensure that the nonlinear model is valid along the known resistive load line at millimeter-wave frequencies. Good agreement between modeled and experimental measurements has been achieved by using the new model on three different HEMT devices. On the design of the broadband power amplifier, a systematic design procedure has been outlined to ensure sufficient power drive for all stages of amplification across the range of frequency of operation. A full W-band MMIC medium power amplifier has been designed by using this procedure. The fabricated chip delivers between 25 mW and 43 mW of power across 75 GHz to 110 GHz. This is the first MMIC amplifier that could deliver such power across the entire W-band. On the design of the active frequency tripler, a new topology that is based on using three-phase signals has been proposed. It has been theoretically shown that the output of this tripler will have good suppression of unwanted harmonic components. An experimental MMIC tripler shows that better than 18 dB of suppression of the fundamental and second harmonic component has been achieved when the output frequency of the tripler is between 42 GHz and 42.7 GHz.

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Chang, Cing-Cian, und 張行憲. „Simulation of Electrical Circuit of Vibration Power Generator“. Thesis, 2011. http://ndltd.ncl.edu.tw/handle/97116486985433353846.

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碩士
華梵大學
機電工程學系博碩專班
99
The simulation of electrical circuit of vibrational power generator is presented. Each element in the electrical circuit is introduced and the behavior of this circuit is simulated using commercial code MULTISIM.The DC voltage output is investigated through harmonic vibration input and their relations are compared. Furthermore, the output voltage is simulated at different output loadings when the input voltage is an impulse function. Results show that the output voltage decays very fast as the output loading is very large.

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