Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

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In this work, the accurate representation of transmission lines for the digital simulation of electromagnetic transients in power systems has been examined. A model has been developed that accounts for the frequency dependence and distributed nature of the line parameters over the entire frequency range. This model can easily be incorporated into a time-domain network solution of the complete power system. The model consists simply of a constant resistence in parallel with a current source evaluated at each time step of the solution. The equivalent resistance results from a finite-step-width discretization of the differential equations of a resistance-capacitance (R-C) network that simulates the line characteristic impedance. The equivalent current source accounts for the time delays and attenuations of the different frequency components of the travelling waves and for the discretization of the time-domain equations. Rational-function approximations are used to synthesize the R-C network and the line propagation ("weighting") function in the frequency domain. These rational approximations allow the corresponding time-domain functions to be obtained directly in a closed-form, thus circumventing the need for numerical inverse Fourier transformations. The numerical technique used to obtain the rational functions yields very accurate, high-order approximations. This technique is based on a direct, step-by-step allocation (and reallocation) of poles and zeros and avoids the instability problems which can be encountered with optimization techniques based on search methods. A series of analytical evaluations and simulation tests were performed in order to assess the validity of the model. The results of these tests show that the model is accurate, fast, and reliable. The model was incorporated into the code of the University of British Columbia's version of Dr. H.W. Dommel's Electromagnetic Transients Program (EMTP). i / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

No description available.

published_or_final_version / Electrical Engineering / Master / Master of Science in Engineering

In this research, we are concerned with obtaining characteristics of a scattering object from transient input-output data. The input is a transient pulse with broad bandwidth. The output is the field scattered by the object. Specifically, we consider two classical structures: First a single lossless dielectric slab backed by a perfect conductor; second, a double-layer lossless dielectric slab backed by a perfect conductor. We begin with two generic solution forms: First, the ray-optic form, which emphasizes local object features; second, the singularity expansion method (SEM) form, which emphasizes object resonances. Using these two forms, we generate a variety of solutions for each structure. For the single slab, we obtain five solution forms for the transient response as follows: The ray-optic, the SEM, two hybrids, and one closed. We find that the input signal plays an important role in the results. We believe the specific hybrid solutions for the slab are new. For the double slab, we find four solution forms as follows: Two ray-optic and two quasi-hybrid. The quasi-hybrid solutions involve a ray-optic expansion in one slab and SEM in the other. We believe the quasi-hybrid forms are new and lead to some interesting comparisons with work by other researchers. As a result of critical study of the various solution types, we reach some conclusions concerning determination of parameters that classify an object (the parametric inverse problem). We find that a given SEM pole set does not always correspond to a unique object. In addition, we show that it is often not possible to relate SEM poles to object size or constitution. Because of these facts, it is necessary to add knowledge of the specific form factor of the object to permit classification. We include some conclusions concerning object identification and point out some areas for future research.

Estudos de transitórios eletromagnéticos são importantes fontes de informação para que os transformadores sejam dimensionados de maneira correta. No entanto, para que tais estudos sejam bem sucedidos, os modelos utilizados devem refletir com fidelidade o comportamento do equipamento. Este trabalho mostra como os elementos do modelo de um transformador são influenciados pelas dimensões geométricas de sua parte ativa. Também introduz uma formulação alternativa, para o transformador saturável (STC) do ATP, desenvolvida dentro do programa MATLAB. Os ramos RL foram representados usando o Método de Integração Trapezoidal e a magnetização foi equacionada pelo Método da Compensação. Uma das contribuições que esta dissertação oferece é a possibilidade de identificar erros numéricos que ocorrem em simulações do ATP, bem como permitir a interpretação de resultados que apresentem oscilações numéricas. / Electromagnetic transient studies are an important source of information to develop transformer dimensioning. But, for the success of that purpose, it is important the models which are being used reflect with fidelity the behavior of the machine. This lecture presents how the transformer model elements are influenced by the active part geometrical dimensions. It also introduces an alternative formulation for the ATP saturable transformer (STC), written inside the MATLAB program. The RL branches are represented using the Trapezoidal Rule and the magnetization by the Compensation Method. One of the contributions of this dissertation is the possibility to identify numerical errors that occur in ATP simulations, and also permit numerical oscillatory results interpretation.

by Siu-Chung Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1988. / Bibliography: leaves 98-102.

A large proportion of water and wastewater systems have traditionally been analyzed and designed without the consideration of the nature, risk, and potential consequence of hydraulic transients. Recent advancements in numerical hydraulic modeling have spawned a specialty hydraulic field based on numerical transient analysis. The current practice within this field often lacks physical understanding and can be misguided by both the current knowledge, technology based limitations, and by the sole reliance on numerical models. This thesis aims to provide insights into some of the shortcomings of current practice and to develop the importance and application of field data based confirmations. The thesis examines the advances in the current field oriented technology for recording transient pressures, and provides examples and insights on how this data can be used both in conjunction with numerical modeling and on its own as a first step to a proposed frequency based transient risk assessment methodology. The thesis establishes definitions and a preliminary methodology for a Transient Risk Index.