Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009. / Full text also available online. Scroll down for electronic link.

Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 28, 2007) Vita. Includes bibliographical references.

To design high frequency complex electromagnetic structures with TLM is not trivial in spite of the simplicity of the fundamental TLM algorithm. This is because TLM is a time and space discretization method in which the entire computational domain must be filled with nodes. In three-dimensional cases, the computational effort to solve realistic problems would soon become intractable unless special techniques are used. To be attractive to the design engineer, field simulation tools must include these advanced techniques automatically in the models. New TLM features and computational techniques have been developed in this thesis to overcome the above mentioned problems. An experimental multi-purpose electromagnetic field simulation tool has also been created to demonstrate the features and techniques developed in this thesis can be easily integrated into a well designed tool. / Graduate

Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-22Bitstream added on 2014-06-13T18:49:34Z : No. of bitstreams: 1 monzani_rc_me_ilha.pdf: 2053077 bytes, checksum: 368877199580a49390152b7476beba1a (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho apresenta um método para determinação de matrizes reais de transformação em sistemas trifásicos considerando a presença de cabos pára-raios. Assim, para as matrizes Z e Y que representam a linha de transmissão, considera-se que os cabos pára-raios não estão implícitos nos valores das fases. Como proposta, usa-se uma matriz de transformação real por toda faixa de frequência de análise. Essa matriz de transformação é uma aproximação da matriz de transformação exata. Para os elementos relacionados com a fase do sistema considerado, a matriz de transformação é composta a partir dos elementos da matriz de Clarke. Nas partes relacionadas com os cabos pára-raios, os elementos da matriz de transformação devem estabelecer uma relação com os elementos das fases considerando o estabelecimento de uma referência homopolar única no domínio dos modos. No caso de linhas de transmissão trifásicas com a presença de dois cabos pára-raios, não é possível obter a diagonalização completa das matrizes Z e Y no domínio dos modos. Isso leva a aplicação de uma matriz média-antimédia com o objetivo de minimizar os erros da composição da matriz de transformação obtida a partir da primeira matriz proposta. Uma segunda proposta de matriz de transformação ainda é aplicada. Os resultados obtidos são analisados por meio de gráficos e condensados em tabelas. Por fim, é aplicada uma rotina de correção com o objetivo de minimização dos erros obtidos para os autovalores e os valores relativos fora da diagonal principal / This paper presents a method for determining real transformation matrices in three-phase systems considering the presence of ground wires. Thus, for the matrices Z and Y represent the transmission line, it is considered that the ground wires are not implied in the phases values. As a proposal, it uses a transformation matrix throughout the frequency range for analysis. This transformation matrix is an approximation of the exact transformation matrix. For items related to the phase of the considered system, the transformation matrix is composed by elements from Clarke’s matrix. In parts related to ground wires, the elements of the transformation matrix must establish a relationship with the elements of the phases considering the establishment of a unique homopolar reference in mode domain. In the case of three phase transmission lines in the presence of ground wires, it is not possible to obtain complete diagonalization of the Z and Y matrices in the mode domain. This leads to the application of a media-antimedia matrix in order to minimize errors in the composition of the transformation matrix obtained from the first proposal. A second proposal of transformation matrix is still applied. The results are analyzed by using graphs and condensed tables. Finally, it is applied a correction routine with the goal of minimizing errors obtained for the eigenvalues and relative values outside the main diagonal

M.A. / Emergence of informal settlements on vacant lands in urban areas results from intuition and political decisions, and sometimes cultural background. So any available vacant land is used for settlement development and dwelling sites. An informal settlement named after Elias Motsoaledi, a political activist of the African National Congress (ANC), was developed in the south-western part of the city of Johannesburg in 1993. Motsoaledi informal settlement was established on a vacant piece of land where there are overhead power lines. Motsoaledi community members that have their dwellings in close proximity and even underneath overhead power lines are exposed to an environment that is surrounded by electrical magnetic fields (EMFs). There are no reported cases of biological and health consequences that have been caused by EMFs as yet. This study aims to focus on the health aspect of persons who have their dwelling in the vicinity of the overhead power lines in Motsoaledi. The high levels of EMFs around Motsoaledi is further excelerated by the zinc structures that are conductive to electricity and may result in electrocution for dwellers that are in the direct vicinity of overhead power lines. Longer exposure to athermal conditions may result in bio-effects and lead to changes in human health. Furthermore, effects from EMFs are possible electrocution, often causing immediate death of persons and destruction of property. Due to the lack of proper planning of informal settlements, such settlements become vulnerable to potential environmental hazards such as the destruction of structures. This study hopes to identify the plight of a particular informal settlement, namely, Motsoaledi as an isolated case to reflect dire conditions of most of the informal settlements around the country.

M.Ing. (Electrical and Electronic Engineering) / This research project sets out to investigate passive L-C coupling circuits as an alternative to transformer-capacitor couplers, with the prime intention to reduce the cost of coupling in power-line communications, hence the title “Compact, Economical Coupling Circuits for Low-Voltage Power-line Communications”. This chapter first presents a short introduction to Power-Line Communications, and then briefly reviews relevant topics surrounding this project. Also discussed, in general, are the standards and regulations for power-line communications i.e. the CENELEC EN50065.1 Standard and the IEEE 1901.2 Standard. This information intends to give the reader guidelines and relevant protocols and/or rules when designing and building communication devices for PLC. This information will also help us in our designs and experimental set-ups as we proceed with this project. The reader will also be introduced to the concept of filtering and impedance matching in communication systems. Emphasis will be laid on the required output signal frequency profile of a coupling band-pass filter. The chapter will define filtering in terms of communications and also discuss the more significant and important parameters in filter circuits. The last section of this chapter will touch on impedance matching and the concept of maximum power transfer, so as to attain maximum signal transfer to the receiver-end.

In this thesis, the finite element method (FEM) is applied to the calculation of frequency-dependent series impedances and shunt capacitances of underground power cables. The principal equations describing the quasi-magnetic fields and static electric fields are solved with FEM based on the Galerkin technique. The Js method and the loss-energy method are derived to calculate the impedances of a multiconductor system from its field solution, and the energy method and the surface charge method are derived to calculate the capacitances. With a single-core (SC) coaxial cable, the suitability of quadratic isoparametric elements and high-order simplex elements are studied, and a suitable division scheme is suggested for the auto-mesh program. The conventional FEM with a field truncation boundary is applied to the impedance calculation of buried SC cables. Suitable locations for the field truncation boundary and division schemes in the earth are studied. The results show that rb ≥ 12[symbol omitted] is required to obtain accurate impedances of shallowly buried cables with the conventional FEM. This requires a large solution region in the earth at low frequencies. A new technique based on the perturbation concept is proposed to reduce the solution region in the earth. Comparisons between the results from the conventional FEM and from the proposed technique with a significantly reduced solution region in the earth show good agreement. In the case studies, the FEM is applied to the parameter calculation of multiphase SC cables, PT cables, sector-shaped cables, and stranded conductors. The numerical results are compared with those from analytical formulas. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

A digital program has been developed which uses the Monte Carlo technique to estimate the risk of failure of transmission line insulation during system switching operations. The effect of overvoltage waveshape on insulation strength is included. A simple electrical system is used to demonstrate the method and to investigate some general aspects of error and parameter sensitivity. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Geomagnetically Induced Currents (GIC's) in B. C. Hydro's 500 kV transmission system have in the past been responsible for the generation of harmonics of 60 Hz, system voltage drops, and misoperation of relay units. Characterization of the associated magnetic storms' spatial scales would further the understanding of GIC generation in the area, and allow advanced warning of potential problems in future power transmission projects. Data collected in 1984 at four substations were analysed to determine lateral variations in geomagnetically induced earth surface electric fields. Inversion techniques were employed to find a variety of solutions that would reproduce the data. Results suggested that the magnetic storms were larger than the area monitored, and that resultant electric fields seen by a large portion of the transmission grid were uniform. Departures from this uniformity in other portions of the electric field models were felt either to be due to earth induction effects, or in some cases, to be artifacts of the data analysis techniques. An experiment designed to determine the controlling factors behind GIC's is outlined. Considerable effort would be required to explicitly determine all electric fields affecting the transmission system / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

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