Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-01T17:54:00Z No. of bitstreams: 1 samuelnevesduarte.pdf: 5789380 bytes, checksum: b5b511b2ce2bf7c5f0c6c6b3ef94a9c1 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-02T15:58:36Z (GMT) No. of bitstreams: 1 samuelnevesduarte.pdf: 5789380 bytes, checksum: b5b511b2ce2bf7c5f0c6c6b3ef94a9c1 (MD5) / Made available in DSpace on 2017-06-02T15:58:36Z (GMT). No. of bitstreams: 1 samuelnevesduarte.pdf: 5789380 bytes, checksum: b5b511b2ce2bf7c5f0c6c6b3ef94a9c1 (MD5) Previous issue date: 2017-03-08 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esta dissertação propõe estratégias de energização/desenergização de um compensador estático síncrono para distribuição. É também proposta uma alteração na topologia do compensador estático síncrono com a inclusão de dois circuitos capazes de realizar o procedimento de energização/desenergização proposto. O primeiro circuito é baseado em um retificador semi–controlado enquanto o segundo circuito é baseado na topologia de um gradador. A metodologia de controle é derivada da modelagem matemática do circuito equivalente formado durante a energização e a desenergização. A equação obtida é resolvida numericamente pelo método de Newton-Raphson e posteriormente usa-se uma aproximação linear por partes para representar os pontos intermediários da curva que relaciona a tensão do barramento CC do compensador com o ângulo de disparo dos tiristores. Um modelo digital do compensador estático, desenvolvido no programa PSIM, e um modelo experimental de pequena escala (3,8 kVA/220 V) são usados para validar a metodologia proposta. Resultados de simulação e experimentais demonstram a eficiência dos controladores de energização e desenergização. / This dissertation proposes strategies to energize/de-energize a distribution static synchronous compensator. It is also proposed a change in the topology of the static synchronous compensator with the inclusion of two circuits capable of performing the energization/de-energization procedure. The first circuit is based on a semi-controlled rectifier while the second one is based on a grader. The control methodology is derived from the mathematical modeling of the equivalent circuit formed during the energization and de-energization process. The resulting equation is numerically solved by the Newton-Raphson method and a piecewise linear method is used to model the curve that relates the DC bus voltage of the compensator to the firing angle of the thyristors. A digital model, in the PSIM program, and a small scale laboratory prototype (3,8 kVA/220 V) are used to validate the proposed methodology. Simulation and experimental results demonstrates the effectiveness of the energization and de-energization controllers.

abstract: Switching surges are a common type of phenomenon that occur on any sort of power system network. These are more pronounced on long transmission lines and in high voltage substations. The problem with switching surges is encountered when a lot of power is transmitted across a transmission line/network, typically from a concentrated generation node to a concentrated load. The problem becomes significantly worse when the transmission line is long and when the voltage levels are high, typically above 400 kV. These overvoltage transients occur following any type of switching action such as breaker operation, fault occurrence/clearance and energization, and they pose a very real danger to weakly interconnected systems. At EHV levels, the insulation coordination of such lines is mainly dictated by the peak level of switching surges, the most dangerous of which include three phase line energization and single-phase reclosing. Switching surges can depend on a number of independent and inter-dependent factors like voltage level, line length, tower construction, location along the line, and presence of other equipment like shunt/series reactors and capacitors. This project discusses the approaches taken and methods applied to observe and tackle the problems associated with switching surges on a long transmission line. A detailed discussion pertaining to different aspects of switching surges and their effects is presented with results from various studies published in IEEE journals and conference papers. Then a series of simulations are presented to determine an arrangement of substation equipment with respect to incoming transmission lines; that correspond to the lowest surge levels at that substation. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2018

<p>This thesis deals with energetic oxygen ions (i.e. single-charged atomic oxygen ions, O+) at altitudes higher than 5 Earth radii (RE) and at latitudes above 75 (toward 90) degrees invariant latitude (deg ILAT) in the dayside polar magnetosphere observed by Cluster. The instrument used in this study is CIS (Cluster Ion Spectrometry experiment) / CODIF (a time-of-flight ion COmposition and DIstribution Function analyser), which covers an energy range from »10 eV up to 38 keV. Cluster detected O+ with energies more than 1 keV (hereafter termed “keV O+”), indicating that energization and/or acceleration process(es) take place in the dayside high-altitude (inside magnetopause) and high-latitude region. These O+ are outflowing (precisely, upward-going along the geomagnetic field lines), and these outflowing keV O+ show a heated (or energized) signature in the velocity distribution as well.</p><p>First, outflowing O+ are observed at the poleward cusp and/or the mantle formed a partial shell-like configuration seen in the velocity distribution. Second, the latitudinal distribution of outflowing O+ (most of them have energies less than 1 keV statistically) observed below 7 RE is consistent with velocity filter effect by the polar convection, while the latitudinal distribution of outflowing keV O+ observed above 7 RE cannot be explained by velocity filter effect only, i.e. this indicates that additional energization and/or acceleration takes place at higher altitudes in the dayside polar region. Thirdly, a tendency to observe outflowing keV O+ for during different geomagnetic conditions is studied. The keV O+ above 9 RE is more often for K p¸5 rather than for K p•3. However the energy of O+ is not dependent on ASY /SYM indices.</p><p>Finally, the dependence on the solar wind conditions is also studied. The energization and/or acceleration of outflowing O+ is controlled by both solar wind moments (except solar wind electric field) and strong southward interplanetary magnetic field (IMF) at the time scale of tens of minutes at only higher altitudes. Further examination shows that solar wind dependence is different at three regions: one is the poleward cusp, another is the low-altitude polar cap, and finally the high-altitude polar cap, combining all the results. There is (a) new energization and/or acceleration process(es) at the high-altitude polar cap. On the other hand, flux enhancement of O+ observed above 5 RE is also controlled by solar wind moments (e.g. solar wind electric field) and strong southward IMF, however the ionospheric changes play a more important role on the flux enhancement of O+.</p>

This thesis deals with energetic oxygen ions (i.e. single-charged atomic oxygen ions, O+) at altitudes higher than 5 Earth radii (RE) and at latitudes above 75 (toward 90) degrees invariant latitude (deg ILAT) in the dayside polar magnetosphere observed by Cluster. The instrument used in this study is CIS (Cluster Ion Spectrometry experiment) / CODIF (a time-of-flight ion COmposition and DIstribution Function analyser), which covers an energy range from »10 eV up to 38 keV. Cluster detected O+ with energies more than 1 keV (hereafter termed “keV O+”), indicating that energization and/or acceleration process(es) take place in the dayside high-altitude (inside magnetopause) and high-latitude region. These O+ are outflowing (precisely, upward-going along the geomagnetic field lines), and these outflowing keV O+ show a heated (or energized) signature in the velocity distribution as well. First, outflowing O+ are observed at the poleward cusp and/or the mantle formed a partial shell-like configuration seen in the velocity distribution. Second, the latitudinal distribution of outflowing O+ (most of them have energies less than 1 keV statistically) observed below 7 RE is consistent with velocity filter effect by the polar convection, while the latitudinal distribution of outflowing keV O+ observed above 7 RE cannot be explained by velocity filter effect only, i.e. this indicates that additional energization and/or acceleration takes place at higher altitudes in the dayside polar region. Thirdly, a tendency to observe outflowing keV O+ for during different geomagnetic conditions is studied. The keV O+ above 9 RE is more often for K p¸5 rather than for K p•3. However the energy of O+ is not dependent on ASY /SYM indices. Finally, the dependence on the solar wind conditions is also studied. The energization and/or acceleration of outflowing O+ is controlled by both solar wind moments (except solar wind electric field) and strong southward interplanetary magnetic field (IMF) at the time scale of tens of minutes at only higher altitudes. Further examination shows that solar wind dependence is different at three regions: one is the poleward cusp, another is the low-altitude polar cap, and finally the high-altitude polar cap, combining all the results. There is (a) new energization and/or acceleration process(es) at the high-altitude polar cap. On the other hand, flux enhancement of O+ observed above 5 RE is also controlled by solar wind moments (e.g. solar wind electric field) and strong southward IMF, however the ionospheric changes play a more important role on the flux enhancement of O+.

Any switching action or lightning stroke on a transmission system causes excessive of voltage, which are propagated through the equipment. The withstand capability of the electrical equipment to these overvoltages is dependent on the rate of rise, peak value and the duration of these overvoltages and are especially critical to information technology (IT) equipment. Whenever there is a probability of these overvoltages appearing across the electrical equipment, they should be limited to a safe value by the application surge arresters of the metal oxide type. However, surge arresters are expensive, an optimal location for these should be found so as to minimise the number of surge arresters used.

In India, with the increase in the number of industries and vehicles the environment is getting more and more polluted. More than industries it is the rapid growth of vehicles which causes serious environmental crisis in the form of air pollution and has become alarming particularly in cities. The industrial and vehicular growth cannot be neglected, as the country’s economic and social well being is largely dependent on them. But this should not come at the cost of our health and eco system. The industrial and vehicular emissions must be controlled in order to keep our air clean. Continued efforts in this direction are being taken up across the globe to investigate an efficient and economical technique. There are many air pollutants being emitted from both natural and manmade sources. The major air pollutants identified as hazardous to human health are nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM), volatile organic compounds (VOC), and sulfur dioxides (SOx). Among these, nitrogen oxides are considered to be difficult to remove. The sources of NOx are thermal power plants, stationary and mobile diesel engines, gasturbine engine, ironore sintering plants and various other smallscale utilities. There are conventionally available technologies to remove NOx such as chemical scrubbing, catalysis etc. But these techniques are either difficult to operate or do not bring down the level of NOx to the required norms imposed by the government. The failure of conventional techniques to remove NOx to the expected limit led to the development of alternative nonconventional techniques. Prominent among these new alternative techniques is electric discharge plasma, where the gas is partially ionized and temperature of electrons is considerably higher than that of ions and background gas molecules. Diesel engines are getting popular due to their inherent merits and their number is increasing considerably. Unfortunately, the exhaust of diesel engine being complex with high oxygen content makes the existing pollution control techniques insufficient particularly with regard to removal of NOx. So there is a need for investigating better technology which can effectively abate the pollutants from diesel engine exhaust. Electric Discharge plasma is one such alternative technique which has been very successful in large volumes of flue gas cleaning and hence, its potential is being explored in the cleaning of small volumes of vehicular exhausts, in particular, diesel engine exhaust. In the present work we investigated the relative performance of different electric discharge plasma reactors, with different type of voltages like AC, DC and pulse. The reactors were evaluated for NOx removal efficiency and NO conversion. This research work is a feasibility study to find whether electric discharge plasma can be used more effectively as an alternative technology for the after treatment of diesel engine exhaust in cascade with some cheaper adsorbents, if necessary. The scope of this qualitative experimental study can briefly be summarized as below: . • To study different reactors for NO conversion and NOx removal . • To study the effect of dielectric pellets in enhancing the radical production which in turn will have a bearing on the chemical reactions . • To study the effect of different types of voltages on the cleansing process . • To propose an efficient reactor system subject to the experimental conditions studied.

Lors de la réalimentation des auxiliaires d'une tranche nucléaire ou hydraulique, l'étape la plus à risque est la remise sous tension brusque du transformateur à cause des surtensions et courants d'appels générés. Ces phénomènes transitoires engendrent des effets très indésirables autant pour le réseau comme pour le transformateur (efforts électrodynamiques sous les bobinages, vibration du circuit magnétique, bruit et vieillissement prématuré du transformateur.) Le but de ces travaux de thèse est de proposer de nouvelles méthodologies permettant d'évaluer les paramètres mal connus (les valeurs des flux rémanents présents dans le circuit magnétique du transformateur avant sa mise sous tension). Face aux problèmes actuelles pour l'estimer (méthode non directe, dérive, imprécision de la mesure de la tension, etc.), deux nouvelles méthodes basées sur la magnétisation préalable du circuit magnétique (méthode de prefluxing) et sur la mesure des flux de fuites du circuit magnétique (méthode de mesure directe de flux par mesure de l’induction magnétique) sont proposées. / During the re-energization of the auxiliaries of a nuclear or hydraulic power plant, the most dangerous step is the re-energization of the power transformer, because of the temporary overvoltage and inrush currents. These transients phenomenon causes undesirable effects for both network and for the power transformer (electrodynamic forces over the windings, the magnetic circuit’s vibration, noise and the premature aging of the transformer). The goal of these thesis is to suggest new methodologies allowing us to evaluate unknown parameters (the residual flux’s values in the magnetic circuit before transformer’s energization). According to the latest problems in order to evaluate it (no direct method, derivation, voltage measurement error, etc) two new methods based on the previous magnetization of the magnetic circuit (prefluxing method) and on the leakage flux measurement of the magnetic circuit (direct measurement of the flux by measuring the magnetic induction method) are proposed.

Orientador: Walmir de Freitas Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-11T01:48:23Z (GMT). No. of bitstreams: 1 Pavani_AhdaPionkoskiGrilo_D.pdf: 1263424 bytes, checksum: a9bc6ef797b8137921a5148c04dc44f7 (MD5) Previous issue date: 2008 / Resumo: Esta tese apresenta o desenvolvimento de diversos métodos analíticos para análise de geradores de indução com rotor em gaiola de esquilo conectados em redes de distribuição de energia elétrica. Foram desenvolvidas metodologias para investigar as seguintes questões técnicas: análise de estabilidade de geradores de indução frente a grandes perturbações; análise de estabilidade de geradores de indução frente a pequenas perturbações; determinação dos valores ótimos dos resistores utilizados por diferentes técnicas de energização de geradores de indução e determinação das correntes de curto-circuito fornecidas por geradores de indução durante faltas desequilibradas. Os métodos analíticos desenvolvidos foram validados por meio de comparações dos resultados obtidos através da aplicação das fórmulas propostas com aqueles obtidos através de simulações computacionais empregando-se típicos programas de análise de sistemas de potência e/ou testes experimentais. Os resultados obtidos comprovam que os métodos analíticos propostos são suficientemente precisos para avaliar o comportamento dos geradores de indução com rotor em gaiola de esquilo, reduzindo o esforço usualmente necessário na realização de análise através de simulações computacionais / Abstract: This thesis presents the development of analytical methods for analysis of squirrel-cage induction generators connected to distribution systems. It was developed analytical methods for evaluation of the following technical issues: large-disturbance stability analysis of induction generators; small-disturbance stability analysis of induction generators; determination of optimum resistances employed by energization devices of induction generators and development of formulas to determine the short-circuit currents of induction generators during unbalanced faults. The analytical methods developed were validated by comparing the results obtained by the proposed formulas with those determined by computational simulations employing typical programs of analysis of power systems and/or experimental tests. The results showed that the proposed analytical methods are enough accurate to evaluate the behavior of the squirrel-cage induction generators, reducing the usually necessary effort for analysis by computational simulations / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica

En s’appuyant sur l’hypothèse frontale du vieillissement (West, 1996), ce travail vise à évaluer le vieillissement normal de capacités frontales (contrôle exécutif, prise de décision, énergisation, métacognition ; Stuss, 2008)et à analyser les liens éventuels entre ces habiletés,l’autonomie et la qualité de vie des aînés. Quarante personnes jeunes (26±5 ans), 40 âgées (68,7±3,7 ans)et 30 très âgées (83,4±3,5 ans) en bonne santé ont participé à notre étude. Les aînés ne montraient pas de traits dépressifs/anxieux, ni de déclin cognitif typiques d’un vieillissement pathologique. Ils présentaient une autonomie et une qualité de vie satisfaisantes.Certaines habiletés cognitives semblent se détériorer après 65 ans (flexibilité, énergisation, prise de décision sous risque explicite, théorie de l’esprit, détection de la coopération/tromperie), d’autres après 80 ans (fluence verbale, mémoire épisodique, dénomination, inhibition,prise de décision en situation ambiguë), d’autres encore seraient préservées (lecture, rappel immédiat,réalisation de tâches de flexibilité spontanée et de temps de réaction simple). La conscience que les sujets ont d’eux-mêmes dépendrait de leur âge. Trois profils distincts de fonctionnement frontal ont été décrits pour chaque groupe de participants, montrant une variabilité intra groupe importante. Le niveau d’autonomie des personnes âgées serait associé au contrôle exécutif,celui de qualité de vie à l’énergisation et à la métacognition. Ces résultats vérifient partiellement nos hypothèses et conduisent à envisager le développement de programmes d’entraînement cognitif multidimensionnels, susceptibles d’influencer la sphère personnelle des aînés. / Starting from the “frontal lobe hypothesis of cognitive aging” (West, 1996), the main objective of this work is to study frontal lobe functions (executive control, decision making,energization, metacognition; Stuss, 2008) and their possible associations with levels of autonomy and quality of life in normal aging. Forty young adults (26±5years), forty old adults (68,7±3,7 years) and thirty very old adults (83,4±3,5 years) participated to our study.These healthy subjects didn’t show any depressive/anxious symptoms and global cognitive decline, which are frequently observed in pathologic alaging. They have a good level of autonomy and general satisfaction of life. A number of frontal lobe abilities seem to decrease after 65 years old (flexibility,energization, explicit decision-making, theory of mind,detection of cooperative and deceptive situations).Other functions decline after 80 years old (verbalfluency, episodic memory, naming, inhibition, implicit decision-making). Reading, immediate recall, realization of spontaneous flexibility and simple reaction time tasks are preserved with aging. Self-consciousness seems to depend on individuals’ age. We have described three different clusters of the frontal functioning for each group of participants, showing the existence of animportant intragroup variability. Old adults’ level of autonomy seems to be associated with the executive control, old adults’ quality of life correlated with the energization and metacognitive functions. These resultsconfirm in part our hypothesis and support the development of multidimensional cognitive training programs, which could impact old adults’ personal sphere.

Choisir entre l'action ou l'inaction est peut-être le type de décision le plus critique auquel un animal peut faire face. Une formalisation simple de ces choix consiste à évaluer les bénéfices attendus (nourriture, argent par exemple) ainsi que les coûts (punitions, pertes de temps ou d'argent) associés à chaque action et d'optimiser le rapport entre récompenses reçues et coûts assumés. Notre motivation à s'engager dans une action donnée dépend donc de la valeur de ce rapport. Dans le domaine de l'économie comportementale, l’optimisation de ce rapport bénéfices/coûts constitue le principe fondamental qui régule et explique le comportement des individus. Dans mes travaux de thèse, j'ai réalisé une implémentation de ces concepts venant de l'économie comportementale en utilisant une forme expérimentalement quantifiable de coûts: l'effort physique. Dans notre vie de tous les jours, si l'on nous demande de choisir entre deux options rapportant les même bénéfices mais demandant différents efforts (par exemple, travailler 3 ou 7 jours par semaine pour le même salaire), nous choisissons habituellement l'option qui nécessite la plus petite dépense d'énergie, en optant donc pour le moindre effort. Néanmoins, l'effort physique a été beaucoup moins étudié en comparaison à d'autres formes de coûts comme le fait de différer la récompense ou d'en augmenter l'incertitude. Le présent travail de recherche a donc pour but de mettre en lumière les bases neurales de la balance récompense / effort dans la prise de décision. Comprendre comment l'effort affecte la dévaluation des potentielles récompenses a un intérêt particulier pour la prise de décisions économiques mais aussi pour la clinique, étant donné que la diminution de la capacité à accepter d'avoir à exercer un effort est un symptôme-clé de nombreuses pathologies comme l'apathie ou la dépression. Nous faisons l’hypothèse que de tels désordres pourraient résulter de deux différents processus comportementaux: (a) une diminution de la sensibilité aux bénéfices futurs et/ou (b) une sensibilité excessive aux coûts potentiels. Ainsi, lorsqu'interrogés sur les raisons pour lesquelles ils ne veulent pas aller au cinéma regarder un film qu'ils apprécient, les patients apathiques peuvent déclarer que (a) le film n'est pas assez bon (soit une plus faible réponse à la valeur attendue), (b) le cinéma est trop loin (soit une plus forte sensibilité à l'effort anticipé). Afin de tester ces hypothèses, nous avons enregistré l'activité de neurones chez le singe pendant des tâches comportementales. Nous avons trouvé que d'une part, la dopamine encode la valeur de l'action future et oriente le comportement vers l'option demandant le moindre effort. D'autre part, la noradrénaline permet à l'individu de faire face à l'effort à venir en réduisant la sensibilité à l'anticipation de l'effort. En utilisant une approche pharmacologique, nous avons démontré que lorsque le niveau de noradrénaline est augmenté, les singes exercent d'avantage d'effort. En outre, nous avons montré que les potentiels locaux de champ dans le cortex pré-frontal ventro-médian, enregistrés dans une tâche comportementale identique, sont modulés par la valeur attendue et prédisent le choix du singe. En résumé, ce travail permet de départager en partie les circuits neuronaux impliqués dans le calcul de la balance récompense / effort, principalement encodée par les neurones dopaminergiques et dans les potentiels locaux de champ au niveau du cortex pré-frontal ventro-médian. Enfin, ce travail souligne le rôle de la noradrénaline dans la mobilisation de l'énergie d'un individu afin de faire face au défi que représente l'effort physique. / There is perhaps no more critical factor for the behaviour of an animal than the way it chooses between action and inaction. A simple way to formalise such choices is to evaluate the predicted benefit (e.g. food, money) and costs (e.g. punishments, losses, delays) associated with each action and optimise the rates at which rewards are received and costs avoided. Our motivation to perform a given action depends upon such value ratio. In the current behavioural economics literature, the optimisation of the benefits/costs ratio stands as the fundamental principle that regulates and explains agents’ behaviour. In my Ph.D. studies, I implement a realistic model of such concepts from behavioural economics by using an empirical type of cost: physical effort. In our everyday life, if we are asked to choose between two options that imply the same reward but different efforts (e.g., working 3 or 7 days per week for the same salary), we usually opt for the alternative that requires the slightest energy expenditure, thus the least effort. However, physical effort has been far less studied compared to other decision costs such as delay or uncertainty. The present Ph.D. work aims at highlighting the neuronal bases of such reward/effort tradeoff. Understanding how effort cost affects the discounting of potential rewards has a clear significance for economic decisions and clinics, since the reduced willingness to exert effort is a key signature of several clinical disorders such as apathy and depression We suggest that disorders such as apathy could result from two different behavioural processes: (a) a decreased responsiveness to future benefits and/or (b) an excessive sensitivity to potential costs. For instance, when asked why they would not go see a movie they like, patients may say that (a) the movie is not good enough (i.e. low responsiveness to expected value) or that (b) the theatre is too far away (i.e. high sensitivity to anticipated effort). To test our hypothesis, we combined behavioural tasks and pharmacological approach with neuron recordings in monkeys, targeting specifically two majors actors of the rewarding and effort system, dopamine and noradrenaline. We found that dopamine and noradrenaline have distinct but complementary roles. On the one hand, dopamine tracks the reward value of future outcomes and orient the behaviour towards the least effortful options. On the other hand, noradrenaline enables subjects to face the effort at hand, reducing the sensitivity to anticipated effort. Using a pharmacological approach, we found that, when we increase noradrenaline, monkeys exerted significantly more effort. Moreover, we have found that local field potentials in the ventromedial prefrontal cortex recorded in the same task encode the expected value and predict action selection. In summary, this Ph.D. work allows to disentangle some of the neuronal circuits implicated in the computation of the reward/effort tradeoff, mainly encoded by dopaminergic neurons and in the local field potential of the ventromedial prefrontal cortex. On the other hand, this work highlights the role of noradrenaline in the energization of behaviour to face the challenge represented by the physical effort.