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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Multi-function monitoring system for harmonic and transient study of power networks /

Chan, Wai-lok. January 1992 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1993.
32

Design and evaluation of active power factor correction circuit operation in discontinuous inductor current mode /

Chan, Chuk-hung. January 1999 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 81-85).
33

Compact fluorescent lamps phase dependency modelling and harmonic assessment of their widespread use in distribution systems : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering in Electrical and Computer Engineering at the University of Canterbury, Christchurch, New Zealand /

Wei, Zhiliang. January 1900 (has links)
Thesis (M.E.)--University of Canterbury, 2009. / Typescript (photocopy). "September 2009." Includes bibliographical references (leaves [53]-58). Also available via the World Wide Web.
34

Direct observation of laser filamentation in high-order harmonic generation /

Painter, John, January 2006 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Physics and Astronomy, 2006. / Includes bibliographical references (p. 61-64).
35

Independent component analysis for harmonic source identification in electric power systems /

Gursoy, Ekrem. Niebur, Dagmar. January 2007 (has links)
Thesis (Ph. D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 139-147).
36

Harmonic state estimation and transient state estimation : a thesis presented for the degree of Doctor of Philosophy in Electrical and Electronic Engineering at the University of Canterbury, Christchurch, New Zealand /

Yu, Kent K. C. January 2005 (has links)
Thesis (Ph. D.)--University of Canterbury, 2005. / Typescript (photocopy). Includes bibliographical references (p. 135-138). Also available via the World Wide Web.
37

Modeling, prediction and mitigation of power distribution system voltage distortion caused by nonlinear loads /

Wang, Yen-Ju, January 2000 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 106-111). Also available on the Internet.
38

Design and development of medium voltage open rack harmonic filters for distribution networks

Meru, Alan Henry Micheni January 2013 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2013 / Harmonic voltages and currents in distribution networks are on the increase in recent times due to the introduction of a proliferation of electronic controlled devices such as variable speed drives. These non-linear devices improve efficiency but distort the supply waveforms. To address the harmonic issues, harmonic filters are used to mitigate distortion levels and prevent damage. These harmonic filters are commonly found at medium voltage levels in power systems. The problem is that knowledge from the design to commissioning stages of these medium voltage harmonic filters are neither well developed nor adequately documented. The aim of this research is to investigate and expound upon the process whilst taking into account all the factors involved throughout the process from bringing such a filter into operation in the real world. Medium voltage harmonic filters are usually the open rack type found in outdoor installations. Capacitors and reactors are the main components used in the construction of such harmonic filters and in some instances resistors are also used. The physical size and spacing of such components determines the construction layout area and how this is done in practice warrants being researched and explained in this thesis. In order to make these factors explicit, a methodology is developed from design, to installation and commissioning and is applied to two networks which are used to prove that the developed methodology is applicable for the different types of harmonic filters designed. The network voltage levels are also different, thus implying that the components will have different design factors. The final arrangements of the harmonic filters are later drawn and shown in three-dimension (3D) as per dimensions. The 3D figures are a further contribution as the design is taken from theory and is ultimately implemented into an installation and construction layout for erection at site. Interviews and surveys are conducted with specialists in industry dealing with harmonic filter applications and the results are analysed as part of implementation of the developed methodology. The design, installation and construction phases are documented and shown to be effective in application and the work disclosed in this thesis will help newcomers to this specialised field and is recommended for use in industry.
39

Flow charts and indices for evaluating true efficiency and effectiveness of harmonic filters in power systems

Amushembe, Hilde January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology / Traditionally, efficiency is defined for sinusoidal networks and not for non-sinusoidal networks. For this reason, the efficiency formula and indices for efficiency calculations are reviewed. The concepts for determining powers, efficiency and power direction of flow in a non-sinusoidal network are explained. A new index „True Efficiency‟ is introduced to represent efficiency in non-sinusoidal circuits. Harmonic filters are installed in networks with harmonic distortion levels above the set standards for harmonic mitigation. However, there are no specific indices for evaluating the effectiveness of filter(s), hence the introduction of the index „Filter Effectiveness‟. Two software tools are utilised to develop flow charts and indices for evaluating true efficiency and effectiveness of harmonic filters in a power system under distorted waveform conditions. In this way, the effect that distortions have on efficiency can be determined and the effectiveness of the mitigation measure in place can be evaluated. The methodologies are developed using a step-by-step approach for two software packages. Three case studies were conducted on a large network. This network has multiple harmonic sources and capacitor banks. The first case study considered a network with two harmonic sources and three capacitor banks of which two are at the point of common coupling (PCC) and one is at a load bus; the second case study considered Case 1 with two capacitor banks at the PCC used as components for the 2nd - order filter and the third case considered Case 2 with a Notch filter added at one of the load buses. The network was simulated using DIgSILENT and SuperHarm software packages. DIgSILENT can calculate powers while SuperHarm gives current and voltages and power is hand calculated. The two packages were used together to test their compatibility and verify the network modelling. For the different investigations conducted, the software-based methodologies developed to calculate true efficiency in a network with multiple harmonic sources and capacitor banks have been shown to be effective. The indices developed for evaluating the effectiveness of harmonic filters proved to be effective too. The two software packages used proved to be compatible as the results obtained are similar. The methodologies can easily be adapted for investigations of other large networks as demonstrated in this study. The true efficiency methodologies are thus recommended for application in this field as it will help determine efficiency for networks with non-linear loads and help mitigate the distortions.
40

Filtro ativo de potência paralelo utilizando inversores monofásicos full-bridge aplicado em sistemas trifásicos a quatro-fios

Campanhol, Leonardo Bruno Garcia 30 August 2012 (has links)
CAPES / Este trabalho apresenta o estudo, projeto e implementação digital usando DSP de um Filtro Ativo de Potência Paralelo (FAPP) trifásico com potência de 4,5kVA, sendo este implementado utilizando três topologias de inversores monofásicos em ponte completa compartilhando o mesmo barramento de tensão CC. O FAPP é utilizado em sistemas trifásicos a quatro-fios para supressão de harmônicos de corrente, compensação de reativos e compensação de desbalanços das correntes de carga. Dentre as características mais relevantes desta topolgia de FAPP, pode-se citar: possibilidade de controle de corrente independente entre as fases; tensão reduzida no barramento CC; isolação galvânica entre o FAPP e a rede elétrica; e modularidade. Os algoritmos adotados para obtenção das correntes de referência de compensação são fundamentados no método de controle baseado no sistema de eixos de referência síncrona (SRF). Estes podem ser empregados em sistemas monofásicos bastando, para isso, a criação de um sistema trifásico fictício. Desse modo, em um sistema trifásico a quatro-fios, cada uma das correntes de fase pode ser controlada de forma independente. Duas estratégias distintas de operação do FAPP são implementadas. Na primeira delas, chamada de Controle de Corrente Independente por Fase (CCIF), o FAPP atua na supressão de correntes harmônicas da carga e compensação de potência reativa. Neste caso, as correntes da rede serão senoidais, no entanto desequilibradas. Na segunda estratégia, além de atuar na supressão de harmônicas da carga e compensação de potência reativa, o FAPP também atua na Compensação dos Desequilíbrios das Correntes de Carga (CDCC). Assim, as correntes da rede, além de senoidais, serão equilibradas. Análises matemáticas são realizadas de forma a obter o modelo matemático que representa o sistema físico do FAPP. Além disso, é apresentada uma metodologia de projeto para a obtenção dos ganhos dos controladores das malhas de corrente e de tensão do barramento CC. Resultados de simulação e experimentais são apresentados de forma a validar o desenvolvimento teórico realizado e avaliar o desempenho do FAPP. / This work deals with the study, design and digital implementation by means of digital signal processor (DSP) of a 4.5kVA three-phase shunt active power filter (SAPF), which is implemented by using three single-phase full-bridge converters sharing the same dc-bus voltage. The SAPF is applied to three-phase four-wire systems performing harmonic current suppression, reactive power compensation and load unbalance compensation. The main characteristics of the SAPF topology can be related: possibility of independent current control; low DC-link voltage; galvanic isolation between the SAPF and the grid utility; and possibility of modular implementation. The algorithms adopted for obtaining the current references are based on the synchronous reference frame (SRF) control method. They can be employed in single-phase systems by creating a fictitious three-phase system. Thereby, in a three-phase four-wire system, it is possible the controlling of each phase current independently. Two different operation strategies of the SAPF are implemented. In the first one, which is called Independent Phase-Current Control (IPCC), the SAPF performs harmonic current suppression and reactive power compensation. In this case, the source current will become sinusoidal although unbalanced. In the second strategy, besides acting in the harmonic current suppression and reactive power compensation, the SAPF performs Load Unbalance Compensation (LUnC). In this case, the source currents will become sinusoidal and balanced. Mathematical analyses are carried out in order to obtain the mathematical model which represents the physical system of the SAPF. Additionally, a design methodology is presented, which is used to obtain the controller gains of both current and dc-bus voltage loops. Simulation and experimental results will be presented in order to validate the presented theoretical development and evaluate the performance of the SAPF.

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