The relay protections of the transmission lines play a fundamental role in the electrical power systems. They permit to ensure the security and the reliability of the electricity transmission from the generators to the final consumers. The objective of a relay protection is to provide a corrective action as quickly as possible when an abnormal condition of the power system is detected. The quickness of the response permits to limit the stress on the equipments of the power system and the consumers, to ensure the security of the people, to improve the power quality and to maintain the stability of the power system.The protective relaying systems have evolved a lot since their first implementation in the 1900’s. However, the electrical power systems are in constant evolution and the reliability of the protective relaying systems becomes more and more challenging. The three main characteristics of the relay protections which are security, dependability and speed must be continuously improved to achieve these objectives. The major relay protections implemented nowadays are based on frequency-domain methods. These methods are intrinsically limited in speed by the phasor estimation of the voltage and current signals. More recent methods based on incremental quantities permitted to break this limitation by working directly in time-domain. Despite the speed of these methods, the dependability is usually limited in order to ensure the security.In this work, it is proposed to develop a time-domain ultra-fast non-pilot distance protection based on a Gamma model of line to improve the security, the dependability and the speed, even for long lines and weak power systems. This protection is composed of a loop selection element, a directional element and a distance element. The target tripping time is 4 ms or less. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

[pt] A transmissão de energia elétrica através de linhas de transmissão aéreas encontra um grau de dificuldade muito grande na constituição de novas faixas de passagem e licenciamento de obras, devido, principalmente, à questão ambiental. Por outro lado, a crescente demanda de energia do sistema elétrico leva o sistema de transmissão a uma progressiva elevação do carregamento de seus componentes, incluindo linhas de transmissão. Desta forma, é fundamental o desenvolvimento de técnicas que permitam aumentar a capacidade de transporte de energia a baixo custo com as instalações existentes e a recapacitação de linhas existentes aparece como uma alternativa a ser analisada nos estudos da expansão do sistema de transmissão. O objetivo deste trabalho é apresentar alternativas de técnicas de recapacitação de linha de transmissão, segundo a ótica de dimensionamento elétrico e da determinação das distâncias mínimas de coordenação de isolamento necessárias na torre, visando maximizar a energia transportada por área ocupada pela faixa da linha de transmissão e com isso, reduzir a necessidade de negociação de novas faixas de passagem com os órgãos de licenciamento e a comunidade, diminuindo o impacto sobre o ambiente e dando maior agilidade na ampliação da capacidade de transporte da malha existente. Busca-se, além disso, identificar, para diferentes níveis de tensão, as possíveis alternativas de recapacitação aplicáveis à linha de transmissão. / [en] The construction of new overhead transmission lines is, nowadays, a difficult activity to achieve, as new right-of- ways are not easily being permitted, due to environmental restrictions. On the other hand, the increase of electrical energy demand leads the transmission system to over load its components, including transmission lines. Therefore, it is extremely important to develop techniques in order to raise energy transmission capacity in low costs using the existent components. Capability increase in existent transmission lines is an alternative to be analyzed in transmission system expansion studies. This dissertation presents techniques to increase capability in existent transmission lines, according to electrical dimensioning and minimum distances needed in towers evaluated in insulation coordination studies. The aim is to maximize the transport capacity of an existent transmission line, reducing the need of negotiating new right-of-ways permit. This study also identifies, for different voltage levels, te available alternatives of a technique to increase the transmission line capability.

[pt] Com o progressivo crescimento das tensões de operação dos sistemas elétricos de transmissão de potência. O método convencional de coordenação de isolamento vai-se tornar ineficiente e, devido a esta circunstância, fez-se necessária a criação do método probabilístico de coordenação de isolamento para surtos de manobra. No presente trabalho é apresentado o já acima citado método probabilístico, um programa de computador que tem por objetivo o cálculo do risco de falha do isolamento de uma linha de transmissão e, ainda, uma análise de sensibilidade do custo de uma linha de 800 KV com os diversos parâmetros que vão influir nesse custo. O presente trabalho vai-se afigurar bastante prático devido ao fato de ele apresentar o que se faz, atualmente, em termos de coordenação de isolamento de linha bem como de subestação / [en] The progressive growth of power system operating voltages imposes several constraints to the application of the conventional approach to insulation coordination. As a consequence a statistical approach to the problem was developed concerning switching surges. This paper explains the method mentioned above and introduces a computer program that calculates the risk of failure for the insulation of a transmission line. A sesitivity cost analysis of a 800 KV transmission line, as well as the various parameters involved, is also presented. Emphasis is given to the practical aspects of this work, for it presents the modern techniques used nowadays in solving the problems of power station and transmision line insulation coordination.

Yes / A new approach of modelling the electromagnetic wave propagation and the penetration of small objects, are investigated and analysed. The travelling electromagnetic wave from source is simulated by time-dependent Maxwell's solutions. Subgridding technique is imposed at the point of interest for observing the electromagnetic field in high resolution. The computational burden caused by a large number of time steps has been parried by implementing the state of art of quasi-static approach. The induced electromagnetic fields near a buried pipeline runs parallel to a 400 kV power transmission lines are presented, and discussed.

Metamaterials are a growing area of interest in the electromagnetics community due to their highly uncommon wave-material interaction characteristics, and they can be modeled using transmission line (TL) based networks. From verification of negative refraction to modeling more complex devices such as invisibility cloaks and field rotators, TL metamaterials offer a tangible solution to modeling novel devices in 1-D, 2-D, and 3-D structures. While currently available TL metamaterials allow for a predictable and easily manufactured network, the need for periodic, regular grids make current TL metamaterials sub-optimal for devices with curved boundaries or realization on curved surfaces. Our work presents the theory and application of TL metamaterials on irregular, nonperiodic grids for modeling 2-D electromagnetic phenomena in TE polarization, allowing for accuracy in curved device boundary modeling and significantly increased adaptability in potential application to curved surfaces. Based on an irregular grid obtained using an unstructured surface mesher, irregularly-shaped individual cells are related to local medium parameters to represent an overall device. The design method is validated using simple scattering problems with known analytical solutions and simulation data through lumped-element circuit- network simulations. The design process is then applied to more complex devices such as the Luneburg lens and field rotator. Capabilities and limitations of this technique are tested and explored. A microstrip based version of this method is subsequently developed and investigated using circuit and full-wave simulation data as well as experiment of a printed-circuit realization.

No / We consider Markov reliability models whose finite state space is partitioned into the set of up states View the MathML source and the set of down states View the MathML source. Given a collection of k disjoint time intervals I¿=[t¿,t¿+x¿], ¿=1,¿,k, the joint interval reliability is defined as the probability of the system being in View the MathML source for all time instances in I1union or logical sumcdots, three dots, centeredunion or logical sumIk. A closed form expression is derived here for the joint interval reliability for this class of models. The result is applied to power transmission lines in a two-state fluctuating environment. We use the Linux versions of the free packages Maxima and Scilab in our implementation for symbolic and numerical work, respectively.

This work examines and implements two different techniques for the estimation of the capacitance and impedance of microstrip-like open structures. Both theories, one developed by Yamashita and Mittra and the other by Itoh and Hebert are based on variational methods. The results for the capacitance and impedance of a microstrip-like structure are calculated numerically and compared with measurements taken using a sample. The results presented in this thesis indicate that the first method produces results with large error and it can be used for microstrip structures with only one strip. The second method produces very accurate results for the microstrip structure under consideration and is the one recommended. / Master of Science

In this thesis a numerical technique is developed determining the propagation constant in waveguides and transmission lines. The technique accounts for both dielectric and conductor losses in a guide having an arbitrary cross section and uses a full-wave solution process. A set of coupled, vector integral equations which characterize the system are derived. The equations enforce the necessary boundary conditions on the tangential electric and magnetic fields at the boundaries separating the conductors and dielectrics. The method of moments (MOM) technique is used to cast the equations into a numerically solvable form. Computed results for various waveguide structures are compared to known or perturbed results for three well-known structures. However, the program is more general and may be applied to other cross-sections. Finally, possible future extensions of the work is presented. / Master of Science

As the boundaries of Moore's Law rapidly approach, research is increasingly turning to exotic materials and metamaterials to advance the capabilities of electronic and micromechanical systems. This thesis presents systems, models, and simulation techniques for novel microfabrication in the realms of silicon carbide (SiC) and metal mesh filters. Through the unification of femtosecond laser pulses, high numerical aperture (NA) objective lenses, and system power and motion control, a system capable of achieving arbitrary 3D features without line-of-sight with aspect ratios up to 109:1 in SiC is developed. Additionally, a model of a direct-write femtosecond-laser-ablation fabricated metal mesh filter (MMF) is simulated in ANSYS High Frequency Structure Simulator (HFSS) and validates the novel fabrication technique. Finally, a transmission-line-theory based MMF model is presented as an alternative to modelling multilayer filters in HFSS. This model produces comparable results to an HFSS simulation with dramatically reduced computational intensity.

The field of superconductivity has recently begun to grow in an exponential fashion. This thesis has briefly described a history of superconductivity discoveries, provided the brief literature review about the superconductors. The superconductor material realization and characterization are provided. The delay line design method is presented and various printed delay lines are constructed. The experimental results are presented and discussed. / Master of Science