Les phénomènes de couplage électromagnétique entre les lignes aé- riennes de transmission d\'énergie et des structures voisines sont inévitables, surtout dans les zones densément peuplées. Les effets indésirables découlants de cette proximité sont variés, allant de l\'établissement des tensions dangereuses à l\'apparition de phénomènes de corrosion dus au courant alternatif. L\'étude de cette classe de problèmes est nécessaire pour assurer la sécurité dans les alentours de la zone d\'interaction et aussi pour préserver l\'intégrité des équipements et des dispositifs présents. Cependant, la modélisation compl ète de ce type d\'application implique la représentation tridimensionnelle de la région d\'intérêt et nécessite des méthodes numériques de calcul de champs spécifiques. Dans ces travaux, des problèmes liés à la circulation de courants électriques dans le sol (ou de couplage dit conductif) seront abordés avec la méthode des éléments finis. D\'autres problèmes résultants de la variation temporelle des champs électromagnétiques (ou de couplage dit inductif) seront aussi considérés et traités avec la méthode PEEC (Partial Element Equivalent Circuit) généralisée. Plus précisément, une condition limite particulière sur le potentiel électrique est proposée pour tronquer le domaine de calcul dans l\'analyse par éléments finis des problèmes de couplage conductif et une formulation PEEC complète pour la modélisation de problèmes de couplage inductif est présentée. Des con gurations tests de complexités croissantes sont considérées pour valider les approches précédentes. Ces travaux visent ainsi à apporter une contribution à la modélisation de cette classe de problèmes, qui tendent à devenir communs avec l\'expansion des réseaux électriques. / Electromagnetic coupling phenomena between overhead power transmission lines and other nearby structures are inevitable, especially in densely populated areas. The undesired effects resulting from this proximity are manifold and range from the establishment of hazardous potentials to the outbreak of alternate current corrosion phenomena. The study of this class of problems is necessary for ensuring security in the vicinities of the interaction zone and also to preserve the integrity of the equipment and of the devices there present. However, the complete modeling of this type of application requires the three- -dimensional representation of the region of interest and needs specific numerical methods for field computation. In this work, the modeling of problems arising from the flow of electrical currents in the ground (the so-called conductive coupling) will be addressed with the finite element method. Those resulting from the time variation of the electromagnetic fields (the so-called inductive coupling) will be considered as well, and they will be treated with the generalized PEEC (Partial Element Equivalent Circuit) method. More specifically, a special boundary condition on the electric potential is proposed for truncating the computational domain in the finite element analysis of conductive coupling problems, and a complete PEEC formulation for modeling inductive coupling problems is presented. Test configurations of increasing complexities are considered for validating the foregoing approaches. These works aim to provide a contribution to the modeling of this class of problems, which tend to become common with the expansion of power grids.

Este trabalho tem por objetivo apresentar o desenvolvimento e a implementação, em uma rotina computacional, de um algoritmo para localização de faltas em linhas de transmissão com compensação série baseado em método heurístico. O algoritmo de localização de faltas proposto neste trabalho é capaz de identificar o ponto de ocorrência da falta utilizando informações sobre os parâmetros da linha de transmissão, os sinais de tensões e correntes registrados nos terminais dessa linha, bem como as características das unidades de compensação série empregadas. O algoritmo desenvolvido no âmbito desta pesquisa foi codificado no ambiente Matrix Laboratory (MATLAB), bem como o método heurístico escolhido (pattern search) e a sua validação foi conduzida a partir de simulações computacionais utilizando modelos de rede implementados no Alternate Transient Program (ATP). / This work aims to describe the development and implementation in a computational routine, an algorithm to locate faults in series-compensated transmission lines based on an heuristic method. The fault location algorithm proposed in this work is capable of identifying the fault point using information about the parameters of the transmission line, voltages and currents signals recorded at the line terminals, as well as the characteristics of the series compensation units. The optimization method used for objective functions was pattern search. The algorithm developed during this research was coded using MATLAB, as well as the heuristic method chosen (pattern search) and its validation was based on computer simulations using network models implemented in ATP.

O presente trabalho tem como objetivo propor uma metodologia para avaliar o impacto das diversas técnicas de repotenciação no desempenho de linhas de transmissão em regime permanente, visto que na atual literatura não existe uma análise abrangente que possa ser aplicada em qualquer linha de transmissão carente de repotenciação. A metodologia busca fornecer subsídios para escolha da técnica mais vantajosa para repotenciar uma linha, utilizando de forma extensiva, os fatores de desempenho, e de forma sintetizada, os índices de mérito agregado, que, avaliados individualmente e/ou em conjunto, propiciam informações qualificadas para as conclusões técnicas. Destaca-se que a proposição dos fatores de desempenho e dos índices de mérito são as principais contribuições deste trabalho. Para complementar a metodologia, uma análise de curtos-circuitos foi proposta. Os resultados da utilização da metodologia foram positivos, possibilitando verificar os ganhos de potência na transmissão de energia. Vale destacar a eficiência dos índices de mérito agregado, que identificaram a melhor técnica de repotenciação de forma sintetizada, resguardando a qualidade e enquadramento dos resultados nas normas regulamentadoras. / This work aims at proposing a methodology to assessing the impact of power upgrade techniques on the steady-state performance of transmission lines, since there is not anything similar to this in the technical literature. The proposed methodology aims at providing technical information to subside the choice of the best power line upgrade technique, by the extensive application of the performance factors and of the aggregate merit indices. It must be pointed out that the proposition of the performance factors and of the aggregate merit indices are the main contributions of this work. Additionally, a short circuit analysis was also proposed to assess the power upgrade techniques. The results after the method application were satisfactory and allowed verifying the surplus of power related to each upgrade technique. The contribution of the aggregate merit indices was very important to identifying the most favorable upgrade technique in a simple way, so that all statutory technical limits were not violated.

In this thesis we present new approaches in the domains of soft fault detection and location in complex wire networks, based on the properties of time reversal. When addressing the detection of soft faults, the idea is to adapt the testing signal to the network under test, instead of being predefined for all the tested networks, as opposed to standard reflectometry techniques. We prove that this approach, which we name the Matched Pulse approach (MP), is beneficial whenever the system is more complex, i.e., its response is richer in echoes, which is opposed to common understanding. The MP analysis is conducted via a formal mathematical analysis, followed by simulation and experimental results validating the proposed approach. In the domain of soft fault location, and based on the DORT (Décomposition de l'Opérateur de Retournement Temporel) properties, we derive a distributive non-iterative method able to synthesize signals that focus on the fault position. Through a statistical study we analyze some of the influencing parameters on the performance of the method, and then simulation and experimental results show that the method is able to synthesize signals directly focalizing on the soft fault position, without the need for iterations.

This thesis presents the design and fabrication of coplanar waveguide to microstrip transitions and planar spiral inductors, and the design of metal-insulator-metal capacitors, a planar band-pass, and a low-pass filter structures as an application for the inductors and capacitors using the RF MEMS technology. This thesis also includes a packaging method for RF MEMS devices with the use of benzocyclobutene as bonding material. The transition structures are formed by four different methods between coplanar waveguide end and microstrip end, and they are analyzed in 1-20 GHz. Very low loss transitions are obtained by maintaining constant characteristic impedance which is the same as the port impedance through the transition structures. The planar inductors are formed by square microstrip spirals on a glass substrate. Using the self-inductance propery of a conductive strip and the mutual inductance between two conductor strips in a proper arrangement, the inductance value of each structure is defined. Inductors from 0.7 nH up to 20 nH have been designed and fabricated. The metal-insulator-metal capacitors are formed by two coplanar waveguide structures. In the intersection, one end of a coplanar waveguide is placed on top of the end of the other coplanar waveguide with a dielectric layer in between. Using the theory of parallel plate capacitors, the capacitance of each structure is adjusted by the dimensions of the coplanar waveguides, which obviously adjust the area of intersection. Capacitors from 0.3 pF up to 9.8 pF have been designed. A low-pass filter and a band-pass filter are designed using the capacitors and inductors developed in this thesis. In addition to lumped elements, the interconnecting transmission lines, junctions and input-output lines are added to filter topologies. The RF MEMS packaging is realized on a coplanar waveguide structure which stands on a silicon wafer and encapsulated by a silicon wafer. The capping chip stands on the BCB outer ring which promotes adhesion and provides semi hermeticity. Keywords: Transition between transmission lines, planar spiral inductor, metal-insulator-metal capacitor, RF MEMS packaging, surface micromachining.

The dissertation comprises the general characteristic of the work, 5 chapters, conclusions and recommendations, references and list of published works on the topic of the dissertation. The dissertation covers 149 pages, 78 illustrations, 17 tables. In introduction chapter the problem topicality is considered, the aims and tasks of the work are formulated, the novelty of the research is described, the author’s reports and publications as well as the dissertation structure are presented. Chapter 1 is intended for the review of literature. The survey of ozone sources in working premises and the environment air is presented as well as methods of the ozone concentration determination and its dispersion simulation are discussed. At the end of the chapter conclusions are formulated and the dissertation tasks are concretized. In chapter 2 the methodology of the ozone concentration determination with the ozone analyzer and passive samplers as well as the measurement methods of aerosol particles and meteorological, microclimatic parameters are described. In chapter 3 the results obtained during experimental investigations are discussed: the ozone concentration changes near technogenic sources of this pollutant, the influence of meteorological and microclimatic parameters on the ozone concentrations changes, the relation of aerosol particles with the ozone concentration. Ozone concentrations measured by different methods are compared and the results of comparative measurements are... [to full text] / Disertaciją sudaro įvadas, 5 pagrindiniai skyriai, darbo išvados ir rekomendacijos, literatūros sąrašas, publikacijų sąrašas. Bendra disertacijos apimtis – 149 puslapiai, 80 iliustracijų, 17 lentelių. Įvadiniame skyriuje nagrinėjamas problemos aktualumas, formuluojamas darbo tikslas bei uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi autoriaus pranešimai ir publikacijos, disertacijos struktūra. Pirmasis skyrius skirtas literatūros apžvalgai. Jame pateikta ozono šaltinių darbo patalpose ir aplinkos ore apžvalga, aptariami ozono koncentracijos nustatymo ir jos sklaidos modeliavimo metodai. Skyriaus pabaigoje formuluojamos išvados ir konkretinami disertacijos uždaviniai. Antrajame skyriuje aprašomi ozono koncentracijos nustatymo ozono analizatoriumi ir pasyviaisiais kaupikliais metodika bei aerozolio dalelių ir meteorologinių, mikroklimato parametrų matavimo metodai. Trečiajame skyriuje aptariami eksperimentinių tyrimų metu gauti rezultatai apie: ozono koncentracijos kitimą prie technogeninių šio teršalo šaltinių, meteorologinių ir mikroklimato parametrų įtaką ozono koncentracijos pokyčiams, aerozolio dalelių sąryšį su ozono koncentracija. Lyginamos ozono koncentracijos matuotos skirtingais metodais ir aptariami lyginamųjų matavimų rezultatai. Ketvirtajame skyriuje pateikti RISK programa sumodeliuoti ozono sklaidos nuo šaltinio rezultatai. Penktajame skyriuje pasiūlytas technologinis sprendimo variantas, leidžiantis sumažinti ozono koncentracijas prie technogeninių... [toliau žr. visą tekstą]

Abstract Adding a dc circuit to an existing transmission line is one method of significantly increasing the power transfer capability of a transmission corridor. The resulting hybrid system has significant coupling between the ac and dc circuits, not only because of the proximity of the circuits, but also from the fact that they may share the same sending end or receiving end ac systems. The resultant interaction produces overvoltages on the dc system which can be somewhat higher than for a conventional dc scheme. This thesis investigates the overvoltages on a hybrid ac-dc transmission system and suggests some design considerations which could be taken into account to reduce stresses on certain critical components which result from such an arrangement. Blocking filters consisting of a parallel L-C combination in series with the dc converter were included to limit the flow of fundamental frequency current in the dc line. This thesis also investigates the proper blocking filter configuration to be used as an incorrectly chosen blocking filter can cause resonance overvoltages on the dc line at fundamental frequency. A method of eliminating dc components of the currents in the transformer windings of a dc converter is presented. The method uses the technique of firing angle modulation. It is shown that merely eliminating the fundamental frequency component on the dc side may not remove this dc component. The impact of such control action at one converter on the other converters in the dc transmission system is also presented. It is also shown that the undesirable side effects of such a scheme include increased generation of non-characteristic harmonies on both the ac and dc sides. The study is performed using an electromagnetic transients simulation program and theoretical calculations.

Abstract Adding a dc circuit to an existing transmission line is one method of significantly increasing the power transfer capability of a transmission corridor. The resulting hybrid system has significant coupling between the ac and dc circuits, not only because of the proximity of the circuits, but also from the fact that they may share the same sending end or receiving end ac systems. The resultant interaction produces overvoltages on the dc system which can be somewhat higher than for a conventional dc scheme. This thesis investigates the overvoltages on a hybrid ac-dc transmission system and suggests some design considerations which could be taken into account to reduce stresses on certain critical components which result from such an arrangement. Blocking filters consisting of a parallel L-C combination in series with the dc converter were included to limit the flow of fundamental frequency current in the dc line. This thesis also investigates the proper blocking filter configuration to be used as an incorrectly chosen blocking filter can cause resonance overvoltages on the dc line at fundamental frequency. A method of eliminating dc components of the currents in the transformer windings of a dc converter is presented. The method uses the technique of firing angle modulation. It is shown that merely eliminating the fundamental frequency component on the dc side may not remove this dc component. The impact of such control action at one converter on the other converters in the dc transmission system is also presented. It is also shown that the undesirable side effects of such a scheme include increased generation of non-characteristic harmonies on both the ac and dc sides. The study is performed using an electromagnetic transients simulation program and theoretical calculations.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 138-145). Also available via the Internet.

Σκοπός της εργασίας είναι η μελέτη της συμπεριφοράς απαγωγέων υπέρτασης στις γραμμές μεταφοράς υψηλής τάσης όταν αυτές καταπονούνται από κεραυνικά πλήγματα. Γίνεται μοντελοποίηση πραγματικών πυλώνων και γραμμών του Ελληνικού συστήματος μεταφοράς, καθώς και αλεξικέραυνων, προσομοίωσή τους στο πρόγραμμα ATP/EMTP και στη συνέχεια μελέτη των υπερτάσεων που εμφανίζονται κατά τη διάρκεια κεραυνικών πληγμάτων πάνω στους αγωγούς προστασίας. / The purpose of this thesis is the study of the behavior of surge arresters on high voltage transmission lines when they are strained by lightning strikes. Steel towers and transmission lines used in the Greek Transmission System and also surge arresters are simulated with ATP/EMTP and the overvoltages that occur during lightning strikes on the shielding wires are studied.