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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Posouzení připravenosti chovů na výpadky elektrické energie na území ORP Soběslav / Power shortage readiness assessment of animal farms in Soběslav municipality

MUSILOVÁ, Karolína January 2017 (has links)
The importance of electrical energy for a contemporary society is increasing. However, most of people don´t realise possible consequences of power outage for agriculture. This thesis aims at presenting an analysis of power outage effects on agricultural breeding in MEC Soběslav area. Considering the aim of the thesis, there is a problem whether the selected breeding farms are ready enough for power outages. The theoretical part of the thesis characterises crisis management, integrated rescue system (IRS), critical infrastructure and electrical grid. The following part of the chapter deals with livestock, poultry and pig breeding, mainly from the point of view of their technological as well as technical equipment. The research part is based on pen and paper interviews with representatives and owners of breeding farms. The research was focused on a degree of dependency on electrical energy in MEC Soběslav area. Two breeding farms in Germany were selected for a comparison with the situation abroad. The results revealed that most of the breeding farms are strongly dependent on electrical energy. Thanks to the last modernisation, automatic feeding or water supplying became a common standard. Unfortunately, most of the modern breeding farms are not able to guarantee these procedures in case of power outage. Great amount of breeding farms don´t have any emergency sources of energy and those that own some, have only limited supplies of fuel. There are no contracts guaranteeing the fuel for the breeding farms. The most problematic situation concerns poultry breeding, where the breeding procedures are wholly controlled by information systems and even the minute failures cause massive losses. Therefore the research problem was confirmed because the breeding farms are not equipped for powers outages. This diploma thesis is supposed to be used for educational purposes or as the means of orientation in the problem for individual breeders. The purpose is the education of presented subjects.
22

Serviços ancilares através da geração distribuíba = reserva de potência ativa e suporte de reativos / Ancillary services provide by distributed generation : active power reserves and reactive support

Moya Chaves, Francisco David 16 August 2018 (has links)
Orientadores: Gilberto de Martino Jannuzzi, Luiz Carlos Pereira da Silva / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T17:50:00Z (GMT). No. of bitstreams: 1 MoyaChaves_FranciscoDavid_D.pdf: 2595862 bytes, checksum: b7384c05596f9dc99d6f2e42bbbe231c (MD5) Previous issue date: 2009 / Resumo: Com a finalidade de constituir os princípios para um futuro marco regulatório no Brasil, que contemple a participação da geração distribuída para o fornecimento de serviços ancilares, este trabalho apresenta uma análise desenvolvida em três grandes áreas assim: técnica, econômica e regulatória. Como objetivo específico do projeto, realiza-se uma analise da utilização da GD para o fornecimento de reservas de potência ativa e suporte de reativos. Para atingir os objetivos dessa pesquisa, o trabalho e realizado em três seções complementares. A primeira parte á uma análise técnica, feita mediante a simulação de sistemas elétricos em regime permanente utilizando a analise de fluxos de carga. Apresentam-se algumas das vantagens e limitações técnicas no uso da GD no fornecimento de potencia ativa e reativa. Apresenta-se também, o estudo sobre o fornecimento de reservas operativas com GD, propondo-se uma metodologia para estabelecer o nível máximo de GD que pode ser instalado sem causar impactos negativos sobre a rede. Apresenta-se o desempenho da GD e seus impactos em situações de entrega de reservas operativas, simulando casos diante de possíveis desligamentos de geradores centralizados. Listam-se diversas tecnologias que podem ser utilizadas em aplicações de GD fornecendo serviços ancilares. A segunda seção é uma análise econômica, na qual, e apresentado o despacho adequado de geradores centralizados e descentralizados, realizada mediante a simulação de cenários de sistemas elétricos com fluxos de carga ótimos. Também e feita uma quantificação da contribuição da GD no fornecimento de suporte de reativos. A análise regulatória lista os aspectos a serem considerados num marco regulatório que permita o fornecimento de serviços ancilares através da GD para o futuro mercado de eletricidade no Brasil. Este trabalho, conseqüentemente, conceitua a GD; especifica suas aplicações; evidencia as suas vantagens; lista os segmentos potencialmente geradores e os principais agentes operantes da GD; aponta as tecnologias ora disponíveis e aquelas em processo de desenvolvimento; mostra, generalizadamente, os aspectos legais e institucionais vigentes que influenciam a GD; detalha as principais barreiras a sua inserção como uma alternativa complementar, no fornecimento de servicos ancilares tão necessários nos sistemas elétricos / Abstract: In order to set the principles for a future regulatory framework in Brazil which involves the participation of distributed generation (DG) to provide ancillary services; this work presents an analysis developed in three broad areas, technical, economic and regulatory. A specific objective of the project is to make an analysis of the use of the DG for the supply of active power reserves and reactive support. To achieve the objectives of this research it is necessary to develop three additional sections. The first part is a technical analysis done through the simulation of electrical systems on a permanent regime that uses the analysis of power flows. There are some advantages and technical limitations in the use of DG for the supply of active and reactive power. This part also presents the study on the provision of operating reserves with DG, and proposes a methodology to establish the level of DG, which can be installed without causing negative impacts on the network. In addition to this, this section shows the performance of DG and its impact in case of delivery of operating reserves, simulating some cases before possible disconnections of centralized generators. Finally, it lists different technologies that can be used in applications of DG provided with ancillary services. The second section is an economic analysis which is presented in the appropriate order that centralized and decentralized generators are made by the simulation of scenarios in electrical systems with optimal power flows. It is a quantification of the contribution of DG in the provision of reactive support. The analysis lists the regulatory aspects to be considered in a regulatory framework that enables the provision of ancillary services through the DG for the future market of electricity in Brazil. This work, therefore, conceptualizes a DG; specifies its applications highlighting their advantages, listing segments and potentially generating the key players involved in DG; outlines the technologies now available and those in the development process; shows generally, the legal and institutional force affecting DG; details the key barriers to their inclusion as an additional alternative in the provision of ancillary services as needed in the electrical systems / Doutorado / Engenharia Mecanica / Doutor em Planejamento de Sistemas Energéticos
23

Diagnostico do uso de energia de um frigorifico de frangos de corte enfatizando medidas de eficiencia energetica / Diagnosis of the use of electric energy of slaugterhouse chicken emphasing action of energy efficiency

Bueno, Leda Gobbo de Freitas 29 February 2008 (has links)
Orientador: Luiz Antonio Rossi / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-11T11:07:23Z (GMT). No. of bitstreams: 1 Bueno_LedaGobbodeFreitas_D.pdf: 3460239 bytes, checksum: 352ebe782b90ca7094650917d0d00794 (MD5) Previous issue date: 2008 / Resumo: Nos abatedouros, as operações que se desencadeiam na ante mortem até o armazenamento do produto final são intensamente dependentes da energia elétrica e respondem, em parte, pela qualidade do produto final. Este trabalho teve como objetivo diagnosticar, analisar e propor soluções que conduzam ao uso racional da energia elétrica, sem interferir, ou manter, a qualidade do produto final nas linhas de produção de um frigorífico de frangos de corte, incluindo o processo de armazenamento que usa câmaras de resfriamento e congelamento. Este trabalho foi realizado em um frigorífico de abate de frangos de corte, situado no estado de São Paulo, SP, no período de 2004 a 2008. Através das análises verificou-se que os compressores da sala de máquinas, responsáveis pela manutenção do frio dos ambientes refrigerados, apresentaram o maior consumo de energia elétrica no frigorífico, cerca de 97%. Observou-se que em nenhum dos motores elétricos avaliados, o fator de potência, atinge o valor recomendado pela ANEEL, e que possivelmente com a implantação de medidas de conservação de energia elétrica, indicadores de eficiência energética, como o fator de carga e o consumo específico, podem ser otimizados. A temperatura média do ar dos ambientes refrigerados, com exceção das câmaras de resfriamento, não atende as recomendações da portaria n° 210 do Ministério da Agricultura e Abastecimento de 1998. Entretanto observou-se que o comportamento da temperatura média do ar, nas câmaras de resfriamento, apresentou oscilações, ficando acima ou no limite superior da faixa de temperatura recomendada por esta portaria. No mapeamento da temperatura do ar, foram identificadas áreas com médias diferentes no interior da câmara de resfriamento 2 e no túnel de congelamento. A temperatura média da água dos resfriadores por imersão e a percentagem de absorção de água apresentaram valores condizentes aos recomendados pela portaria supracitada. Concluiu-se haver falhas no uso da energia elétrica, demonstrando necessidade da implementação de um plano de ação que vise a conservação e o uso racional da energia e conseqüente redução nos custos gerados para produção de carne de frango / Abstract: In the slaughterhouses the operations that if unchain in the one before slaughter until the storage of the end item are intensely dependents of the electric energy and answer for the final product quality. This work had as objective to diagnosis, to analyze and to consider solutions that lead to the rational use of the electric energy without intervening or keeping the product quality in the lines of production of one cold storage room of broiler including the storage process that uses chambers of cooling and freezing. This work was carried through in one cold storage room of slaughter of chicken situated in the state of São Paulo, SP in the period of 2004 the 2008. Through the analyses it was verified that the compressors of the room of machines, responsible for the maintenance of the cold of cooled environments, had presented the biggest consumption of electric energy in the cold storage room, about 97%. It was observed that in none of the evaluated electric engines, the potency factor, reaches the value recommended for the ANEEL, and that possibly with the implantation of measures of conservation of electric energy pointers of energy efficiency as the load factor and the specific consumption they can be optimized. The average temperature of the air of cooled environments with exception of the cooling chambers does not take care of the recommendations of current law. However it was observed that the behavior of the average temperature of air, in the cooling chambers presented oscillations being above or in the superior limit of the band of temperature recommended for this it would carry. In the mapping of the temperature of air areas with different averages in the chamber of cooling 2 and in the tunnel of freezing had been identified. The average temperature of the water of the coolers for immersion and the percentage of water absorption had presented accepted values to the recommended ones for would carry above-mentioned. It was concluded to have imperfections in the use of the electric energy demonstrating necessity of the implementation of an action plan that aims at the conservation and the rational use of the energy and consequence reduction in the costs generated for production of broiler / Doutorado / Construções Rurais e Ambiencia / Doutor em Engenharia Agrícola
24

OPTIMIZATION-BASED OPERATION AND CONTROL APPROACHES FOR IMPROVING THE RESILIENCE OF ELECTRIC POWER SYSTEMS

Dakota James Hamilton (17048772) 27 September 2023 (has links)
<p dir="ltr">The safe and reliable delivery of electricity is critical for the functioning of our modern society. However, high-impact, low-probability (HILP) catastrophic events (such as extreme weather caused by climate change, or cyber-physical attacks) pose an ever-growing threat to the power grid. At the same time, modern advancements in computational capabilities, communication infrastructure, and measurement technologies provide opportunities for new operation and control strategies that enhance the resilience of electric power systems to such HILP events. In this work, optimization-based operation and control approaches are proposed to improve resilience in two power systems applications. First, a real-time linearized-trajectory model-predictive controller (LTMPC) is developed for ensuring voltage, frequency, and transient (rotor angle) stability in systems engineered to operate as microgrids. Such microgrids are capable of seamlessly transitioning from grid-connected operation to an islanded mode and thus, enhance system resilience. The proposed LTMPC enables rapid deployment of such systems by reducing engineering costs and development time while maintaining stable operation. On the other hand, some power systems, such as distribution feeders, are not designed to operate as standalone microgrids. For these cases, a method is proposed for forming ad-hoc microgrids from intact sections of the damaged feeder in the aftermath of a HILP event. A feeder operating center-on-a-laptop (FOCAL) is introduced that coordinates the control of possibly hundreds of inverter-interfaced distributed energy resources (e.g., rooftop solar, battery storage) to improve system resilience. Theoretical analysis as well as numerical case studies and simulations of the proposed strategies are presented for both applications.</p>
25

DFIG-BASED SPLIT-SHAFT WIND ENERGY CONVERSION SYSTEMS

Rasoul Akbari (13157394) 27 July 2022 (has links)
<p>In this research, a Split-Shaft Wind Energy Conversion System (SS-WECS) is investigated</p> <p>to improve the performance and cost of the system and reduce the wind power</p> <p>uncertainty influences on the power grid. This system utilizes a lightweight Hydraulic Transmission</p> <p>System (HTS) instead of the traditional gearbox and uses a Doubly-Fed Induction</p> <p>Generator (DFIG) instead of a synchronous generator. This type of wind turbine provides</p> <p>several benefits, including decoupling the shaft speed controls at the turbine and the generator.</p> <p>Hence, maintaining the generator’s frequency and seeking maximum power point</p> <p>can be accomplished independently. The frequency control relies on the mechanical torque</p> <p>adjustment on the hydraulic motor that is coupled with the generator. This research provides</p> <p>modeling of an SS-WECS to show its dependence on mechanical torque and a control</p> <p>technique to realize the mechanical torque adjustments utilizing a Doubly-Fed Induction</p> <p>Generator (DFIG). To this end, a vector control technique is employed, and the generator</p> <p>electrical torque is controlled to adjust the frequency while the wind turbine dynamics</p> <p>influence the system operation. The results demonstrate that the generator’s frequency is</p> <p>maintained under any wind speed experienced at the turbine.</p> <p>Next, to reduce the size of power converters required for controlling DFIG, this research</p> <p>introduces a control technique that allows achieving MPPT in a narrow window of generator</p> <p>speed in an SS-WECS. Consequently, the size of the power converters is reduced</p> <p>significantly. The proposed configuration is investigated by analytical calculations and simulations</p> <p>to demonstrate the reduced size of the converter and dynamic performance of the</p> <p>power generation. Furthermore, a new configuration is proposed to eliminate the Grid-</p> <p>Side Converter (GSC). This configuration employs only a reduced-size Rotor-Side Converter</p> <p>(RSC) in tandem with a supercapacitor. This is accomplished by employing the hydraulic</p> <p>transmission system (HTS) as a continuously variable and shaft decoupling transmission</p> <p>unit. In this configuration, the speed of the DFIG is controlled by the RSC to regulate the</p> <p>supercapacitor voltage without GSC. The proposed system is investigated and simulated in</p> <p>MATLAB Simulink at various wind speeds to validate the results.</p> <p>Next, to reduce the wind power uncertainty, this research introduces an SS-WECS where the system’s inertia is adjusted to store the energy. Accordingly, a flywheel is mechanically</p> <p>coupled with the rotor of the DFIG. Employing the HTS in such a configuration allows the</p> <p>turbine controller to track the point of maximum power (MPPT) while the generator controller</p> <p>can adjust the generator speed. As a result, the flywheel, which is directly connected</p> <p>to the shaft of the generator, can be charged and discharged by controlling the generator</p> <p>speed. In this process, the flywheel energy can be used to modify the electric power generation</p> <p>of the generator on-demand. This improves the quality of injected power to the</p> <p>grid. Furthermore, the structure of the flywheel energy storage is simplified by removing</p> <p>its dedicated motor/generator and the power electronics driver. Two separate supervisory</p> <p>controllers are developed using fuzzy logic regulators to generate a real-time output power</p> <p>reference. Furthermore, small-signal models are developed to analyze and improve the MPPT</p> <p>controller. Extensive simulation results demonstrate the feasibility of such a system and its</p> <p>improved quality of power generation.</p> <p>Next, an integrated Hybrid Energy Storage System (HESS) is developed to support the</p> <p>new DFIG excitation system in the SS-WECS. The goal is to improve the power quality</p> <p>while significantly reducing the generator excitation power rating and component counts.</p> <p>Therefore, the rotor excitation circuit is modified to add the storage to its DC link directly.</p> <p>In this configuration, the output power fluctuation is attenuated solely by utilizing the RSC,</p> <p>making it self-sufficient from the grid connection. The storage characteristics are identified</p> <p>based on several system design parameters, including the system inertia, inverter capacity,</p> <p>and energy storage capacity. The obtained power generation characteristics suggest an energy</p> <p>storage system as a mix of fast-acting types and a high energy capacity with moderate</p> <p>acting time. Then, a feedback controller is designed to maintain the charge in the storage</p> <p>within the required limits. Additionally, an adaptive model-predictive controller is developed</p> <p>to reduce power generation fluctuations. The proposed system is investigated and simulated</p> <p>in MATLAB Simulink at various wind speeds to validate the results and demonstrate the</p> <p>system’s dynamic performance. It is shown that the system’s inertia is critical to damping</p> <p>the high-frequency oscillations of the wind power fluctuations. Then, an optimization approach</p> <p>using the Response Surface Method (RSM) is conducted to minimize the annualized</p> <p>cost of the Hybrid Energy Storage System (HESS); consisting of a flywheel, supercapacitor, and battery. The goal is to smooth out the output power fluctuations by the optimal</p> <p>size of the HESS. Thus, a 1.5 MW hydraulic wind turbine is simulated, and the HESS is</p> <p>configured and optimized. The direct connection of the flywheel allows reaching a suitable</p> <p>level of smoothness at a reasonable cost. The proposed configuration is compared with the</p> <p>conventional storage, and the results demonstrate that the proposed integrated HESS can</p> <p>decrease the annualized storage cost by 71 %.</p> <p>Finally, this research investigates the effects of the reduced-size RSC on the Low Voltage</p> <p>Ride Through (LVRT) capabilities required from all wind turbines. One of the significant</p> <p>achievements of an SS-WECS is the reduced size excitation circuit. The grid side converter is</p> <p>eliminated, and the size of the rotor side converter (RSC) can be safely reduced to a fraction</p> <p>of a full-size excitation. Therefore, this low-power-rated converter operates at low voltage</p> <p>and handles the regular operation well. However, the fault conditions may expose conditions</p> <p>on the converter and push it to its limits. Therefore, four different protection circuits are</p> <p>employed, and their effects are investigated and compared to evaluate their performance.</p> <p>These four protection circuits include the active crowbar, active crowbar along a resistorinductor</p> <p>circuit (C-RL), series dynamic resistor (SDR), and new-bridge fault current limiter</p> <p>(NBFCL). The wind turbine controllers are also adapted to reduce the impact of the fault</p> <p>on the power electronic converters. One of the effective methods is to store the excess energy</p> <p>in the generator’s rotor. Finally, the proposed LVRT strategies are simulated in MATLAB</p> <p>Simulink to validate the results and demonstrate their effectiveness and functionality.</p>
26

Development of a supervisory system for maintaining the performance of remote energy management systems / Johan Nicolaas du Plessis

Du Plessis, Johan Nicolaas January 2014 (has links)
Energy services companies (ESCOs) typically implement energy management systems (EMSs) as part of Demand-Side Management (DSM) projects on South African mines. After DSM project completion, the mine becomes responsible for maintaining the performance of the EMS. Due to a lack of experience in using specialised EMSs, mines typically contract ESCOs for EMS maintenance. However, maintaining a large number of EMSs remotely is a resource-intensive task because of time wasted on daily monitoring and travelling to perform on-site maintenance. For the same reason, remote maintenance technologies have become widely used to maintain cellular devices, vehicles and industrial equipment. Mine EMSs typically control production-critical systems that in turn ensure safe working conditions underground. EMSs execute highly specialised control philosophies to achieve electrical energy management, while ensuring safe and productive system operation. None of the work done on remote maintenance, however, provides an integrated solution to maintain the performance of a growing number of these specialised EMSs. As part of this study, a supervisory system was developed to optimise remote maintenance of different EMS technologies. The supervisory system builds on the fundamentals of existing remote maintenance technologies, complemented by comprehensive diagnostics of specialised EMS technologies. This is possible through automated diagnostics of EMS components, the control philosophy and overall EMS performance. Maintenance management forms part of the supervisory system to ensure that maintenance is performed with optimal efficiency. A system implementation was executed to prove the feasibility of the supervisory system. The functional operation of the system was verified with pre-set scenarios that simulated day-to-day operation and common fault diagnostic events. As part of the case studies conducted for this thesis, the supervisory system was integrated with three distinct EMS technologies implemented on South African mines. To support the results of these case studies, the system validation was extended through integrations with seven additional EMSs. For the first time, a supervisory assessed the condition of the EMS components, the control philosophy and DSM performance comprehensively. The results (obtained over a period of more than six months) indicated that the average operational availability of EMS components improved from 90% to 97%. The average EMS performance improved from 1.8 MW to 2.5 MW, an improvement of 39%. The resulting electricity cost reduction achieved on the case studies accumulated to approximately R6 million during the respective assessment periods. The supervisory system facilitated efficient EMS maintenance, thus reducing the risk of unsafe working conditions and production interruptions. The system also allowed maintenance personnel to improve the diagnostic process continually, thus aligning with the standards documented in ISO 50001:2011 (ISO, 2011) regarding continual improvement of electrical energy management initiatives. The new supervisory system is scalable, thus an ESCO can maintain the performance of a growing number of EMSs remotely. Results of this study support further supervisory system integration with compatible EMS technologies, and expansion to new EMS technologies. The modular design of the supervisory system provides a basis for the development of a cross-industry platform for maintaining EMS performance. / PhD (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014
27

Development of a supervisory system for maintaining the performance of remote energy management systems / Johan Nicolaas du Plessis

Du Plessis, Johan Nicolaas January 2014 (has links)
Energy services companies (ESCOs) typically implement energy management systems (EMSs) as part of Demand-Side Management (DSM) projects on South African mines. After DSM project completion, the mine becomes responsible for maintaining the performance of the EMS. Due to a lack of experience in using specialised EMSs, mines typically contract ESCOs for EMS maintenance. However, maintaining a large number of EMSs remotely is a resource-intensive task because of time wasted on daily monitoring and travelling to perform on-site maintenance. For the same reason, remote maintenance technologies have become widely used to maintain cellular devices, vehicles and industrial equipment. Mine EMSs typically control production-critical systems that in turn ensure safe working conditions underground. EMSs execute highly specialised control philosophies to achieve electrical energy management, while ensuring safe and productive system operation. None of the work done on remote maintenance, however, provides an integrated solution to maintain the performance of a growing number of these specialised EMSs. As part of this study, a supervisory system was developed to optimise remote maintenance of different EMS technologies. The supervisory system builds on the fundamentals of existing remote maintenance technologies, complemented by comprehensive diagnostics of specialised EMS technologies. This is possible through automated diagnostics of EMS components, the control philosophy and overall EMS performance. Maintenance management forms part of the supervisory system to ensure that maintenance is performed with optimal efficiency. A system implementation was executed to prove the feasibility of the supervisory system. The functional operation of the system was verified with pre-set scenarios that simulated day-to-day operation and common fault diagnostic events. As part of the case studies conducted for this thesis, the supervisory system was integrated with three distinct EMS technologies implemented on South African mines. To support the results of these case studies, the system validation was extended through integrations with seven additional EMSs. For the first time, a supervisory assessed the condition of the EMS components, the control philosophy and DSM performance comprehensively. The results (obtained over a period of more than six months) indicated that the average operational availability of EMS components improved from 90% to 97%. The average EMS performance improved from 1.8 MW to 2.5 MW, an improvement of 39%. The resulting electricity cost reduction achieved on the case studies accumulated to approximately R6 million during the respective assessment periods. The supervisory system facilitated efficient EMS maintenance, thus reducing the risk of unsafe working conditions and production interruptions. The system also allowed maintenance personnel to improve the diagnostic process continually, thus aligning with the standards documented in ISO 50001:2011 (ISO, 2011) regarding continual improvement of electrical energy management initiatives. The new supervisory system is scalable, thus an ESCO can maintain the performance of a growing number of EMSs remotely. Results of this study support further supervisory system integration with compatible EMS technologies, and expansion to new EMS technologies. The modular design of the supervisory system provides a basis for the development of a cross-industry platform for maintaining EMS performance. / PhD (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014
28

Estudo da reação de oxidação de etanol em ânodos de células a combustível SOFC / Studies of ethanol oxidation reaction over SOFC anodes

Saglietti, Guilherme Gonçalves de Aquino 06 May 2019 (has links)
Células a combustível de óxido sólido (SOFC) produzem energia elétrica em elevadas temperaturas e, devido a isto, não necessitam da utilização de metais nobres para a promoção das reações eletródica em seus eletrodos. Entretanto, independentemente deste fato, quando biocombustíveis são utilizados diretamente há a formação de carbono nos eletrodos, o que promove a rápida degradação do dispositivo. Neste trabalho são preparados e estudados catalisadores anódicos baseados em níquel e num segundo metal para utilização como pré-camada anódica em células a combustível SOFC operando a 800 °C visando-se mitigar os efeitos da formação de carbono, aumentar o desempenho e prolongar a vida útil do dispositivo em operação com biocombustíveis, especialmente o etanol. Foram estudados os metais Co, Cu, Ru, Pd, Rh, e Ba. Os materiais foram caracterizados fisicamente para se estabelecer as suas estruturas cristalográficas bem como composição e morfologia. Estudou-se também o desempenho eletroquímico através do levantamento de curvas de polarização em estado estacionário, espectroscopia de impedância eletroquímica e cronoamperometria. Por fim, utilizou-se a técnica de espectrometria de massas para identificação de produtos reacionais. Da maneira como utilizadas, as camadas préanódicas atuaram como um filtro catalítico, promovendo reações de reforma e entregando ao ânodo um combustível com menor teor carbonáceo. Desta maneira todos os materiais mostraram-se em certa extensão capazes de promover a operação de células SOFC com etanol. Observou-se também atividade catalítica para outros combustíveis, sendo possível até mesmo a operação com metano e propano. Para fins deste estudo, o material que demonstrou melhor comportamento ante a operação com etanol tratou-se do NiRu, sendo alcançadas densidades de potência próximas a 0,9 W cm-2 a 500 mV. Em teste de durabilidade observou-se que a célula contendo este material operou por 150 h ininterruptas, ante 15 minutos possíveis para a célula sem proteção. / Solid Oxide Fuel Cells produce electrical energy at high temperatures without the need of noble metals. However, when a biofuel is directly used, carbon formation takes place, also known as \"coking\", which promotes rapid system degradation. In this work, bimetallic nickel based anodic catalysts are prepared and studied as anode prelayers for SOFC working at 800 °C fed with ethanol. The aims are to mitigate the effects of coking, improve the cell performance and extend the life usage of these devices when operating with biofuels, specially ethanol. As second metals Co, Cu, Ru, Pd, Rh and Ba were studied. The catalysts were physically characterized to establish their crystal structures as well as their chemical composition, and morphology. Electrochemical performance was studied using steady state olarization curves, electrochemical impedance spectroscopy and chronoamperometry for lifetime tests. Mass spectrometry was used in order to identify reactional products. In the way they were conceived and used, the anodic pre-layers worked as catalytic filters, promoting reforming reactions, delivering to anode surface a fuel with lower carbon content. All the studied materials showed in some extent activity for SOFC operating with biofuels, even making possible the operations with methane and propane. In the studies, NiRu material showed the best performance when operating with ethanol, reaching power densities as high as 0,9 W cm-2 at 500 mV. Endurance test made with this material showed that by using the NiRu based anode pre-layer fed with ethanol, under different load conditions, it is possible to operate the SOFC for about 150 h without interruption, versus 15 minutes for the uncovered anode.
29

Připravenost Nemocnice Strakonice, a.s. na výpadek kritické infrastruktury / The preparedness of Hospital Strakonice to critical infrastructure failure

VODVÁŘKA, Martin January 2019 (has links)
The failure of critical infrastructure is one of the most serious threats, especially in health care. Hospitals and health care facilities play an irreplaceable role, so it is essential to maintain the capacity and responsiveness of the health care facility as a whole during the blackout period. In energy, which is one of the areas of critical infrastructure, power outages can occur at any time, so the hospital should be unconditionally prepared for this crisis situation and the resulting impacts. The theoretical part defines the basic concepts in the health care system located in crisis preparedness and crisis planning, as well as necessary documentation and electrical regulations. The following chapter deals with the critical infrastructure from the perspective of national and international legislative documents and links to the means for its protection. The last part explains the principle of the electricity system of the Czech Republic and describes the production, transmission and distribution of electricity. The topic of Blackout outlines the issue of domestic and foreign cases. The practical part introduces the environment of the Hospital Strakonice, a.s., further describes the available alternative sources of electric energy and legislative standards of the company, on the principles of which it respects crisis preparedness. Three specific cases explain how critical infrastructure failures can be addressed, prevent unwanted situations, respond to problems promptly, and take remedial action. For elaboration of my diploma thesis I used basic scientific procedures which are observation, consultation, analysis and comparison. The aim of the thesis was to map the readiness of the health and non-health part of the hospital to the impact of the failure of critical infrastructure, which could be described as satisfactory. The findings will be forwarded to the Chairman of the Board of Directors and the Crisis Management Department of the Strakonice Hospital, a.s. to assess the possible consequences and effective preparedness for critical infrastructure failures. The results can be used as study material.
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Calibração do consumo de energia elétrica simulado por um modelo EnergyPlus: estudo de caso do Hospital Universitário da Universidade de São Paulo / Calibration of model that simulate the USP university hospital electric energy consumption with EnergyPlus software

Silva, Pedro Paulo Fernandes da 23 October 2018 (has links)
A utilização de um modelo computacional para simular o consumo energético de edificações para diferentes fins tornou-se prática comum. Entretanto, para que suas finalidades sejam válidas para prédios em fase de operação é necessário que a simulação passe por uma fase denominada calibração, ou seja, ajuste de seus parâmetros de entrada para verificar que seu resultado esteja coerente com a realidade. Dado esta necessidade, este trabalho tem como objetivo a calibração da energia elétrica simulada por um modelo EnergyPlus do Hospital Universitário da Universidade de São Paulo (HU-USP). Na busca por este objetivo, faz-se a revisão do estado da arte sobre metodologias de calibração baseadas em evidência, ou seja, no qual os ajustes nos parâmetros de entradas baseiam-se em informações coletadas acerca do edifício real. Pela comparação destas metodologias, selecionou-se aquela proposta por Raftery, Keane e O donnell (2011) cuja aplicação mostrou-se mais generalizada para diferentes tipologias de edifícios. As medições disponíveis do HU-USP contra o qual as simulações foram confrontadas foram: consumo de prédio, consumo de uma das duas centrais de água gelada do prédio e medição de 16 equipamentos modulares do tipo split. Os indicadores estatísticos resultantes da comparação destas medições revelaram que, ao final do processo de calibração, apenas o consumo do prédio pôde ser considerado calibrado. A partir da simulação calibrada foram avaliadas quatro alternativas de eficiência energética, duas no sistema de iluminação e duas no sistema de climatização. As experiências acumuladas na calibração da simulação do HU-USP e a identificação de melhores práticas na literatura permitiram, ao final, a elaboração de uma nova metodologia que engloba a abordagem de um prédio com as características de edificações públicas brasileiras. / The use of a computational model for simulation of the energy consumption of buildings for different goals has become common practice. However, in order to use it to simulate operating buildings, it is necessary that the simulation undergoes a process called calibration. This means adjusting simulation input to certify that its output consistently represents the reality. This work objective is to calibrate the electric energy simulated by an energy model of the University Hospital of the University of São Paulo (HU-USP). The state of the art is reviewed in search of evidence-based calibration methodologies. This type of methodologies uses data collected from the real building to change the simulation input. It was selected the methodology proposed by Raftery, Keane and O donnell (2011) which was evaluated as the most generalized approach between the methodologies reviewed. The available measurements of HU-USP against which the simulations were confronted were: building electricity consumption, one (of the two) chilled water plant electricity consumption and the electricity measurement of 16 split type air conditioner. The statistical indicators resulted in comparisons of the measurements revealed, at the end of the calibration process, that only the consumption of the building could be considered calibrated. From the calibrated calibration, four energy efficiency alternatives were simulated, two concerning the lighting system and two concerning the air conditioning system. From the experience accumulated through the calibration of HU-USP electric energy consumption simulation and the identification of the best practices in the literature, it was elaborated a new methodology that includes an approach that deal with brazilian public buildings features.

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