Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis (Dr.-Ing.)--Otto-von-Guericke-Universität Magdeburg, 2004. / "Untersuchungen zur Spannungsqualität in Verteilungsnetze under Verwendung der Spektralanalyse"--p. v. Includes bibliographical references (p. 114-123).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 122-124).

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.Eng.)--University of Louisville, 2007. / Title and description from thesis home page (viewed May 14, 2007). Department of Industrial Engineering. Vita. "May 2007." Includes bibliographical references (p. 34-35).

With advances in technology and the increasing use of power electronic components in the design of household and industrial equipment, harmonic distortion has become one of the major power quality problems in power systems. Identifying the harmonic sources and quantifying the contributions of these harmonic sources provides utility companies with the information they require to effectively mitigate harmonics in the system. This thesis proposes the use of observers for harmonic estimation and harmonic source identification. An iterative observer algorithm is designed for performing harmonic estimation in measured voltage or current signals taken from a power distribution system. The algorithm is based on previous observer designs for estimating the power system states at the fundamental frequency. Harmonic estimation is only carried out when the total harmonic distortion (THD) exceeds a specified threshold. In addition, estimation can be performed on multiple measurements simultaneously. Simulations are carried out on an IEEE distribution test feeder. A number of scenarios such as changes in harmonic injections with time, variations in fundamental frequency and measurement noise are simulated to verify the validity and robustness of the proposed iterative observer algorithm. Furthermore, an observer-based algorithm is proposed for identifying the harmonic sources in power distribution systems. The observer is developed to estimate the system states for a combination of suspicious nodes and the estimation error is analysed to verify the existence of harmonic sources in the specified node combinations. This method is applied to the identification of both single and multiple harmonic sources. The response of the observer-based algorithm to time varying load parameters and variations in harmonic injections with time is investigated and the results show that the proposed harmonic source identification algorithm is able to adapt to these changes. In addition, the presence of time delay in power distribution system measurements is taken into consideration when identifying harmonic sources. An observer is designed to estimate the system states for the case of a single time delay as well as multiple delays in the measurements. This observer is then incorporated into the observer-based harmonic source identification algorithm to identify harmonic sources in the presence of delayed measurements. Simulation results show that irrespective of the time delay in the measurements, the algorithm accurately identifies the harmonic sources in the power distribution system.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009 / Traditionally, harmonics are ignored in overall efficiency and energy usage studies. However, in the modern era, power systems contain levels of harmonics which can no longer be ignored by engineers, planners, energy conservationists and economists. The directions of power flows have to be considered when harmonics are present in the power network. A methodology and new formulae for individual and overall efficiency and energy usage is developed at each frequency (f1, h and H) and forms the main contribution to research in this field. Two case studies were conducted; a measurement based laboratory experiment set-up and a simulated case study. In the set-up, measurements of current, voltage and power at different points in the network for the 1st, 5th and 7th frequencies were taken. Current and voltage results were used for hand calculations to prove the measured power flows and directions. The measurements were taken with a Fluke 345 three-phase harmonic power quality analyzer. For the simulated case study, a network was investigated using the DIgSILENT and SuperHarm software packages. Their results were compared and it was found that DIgSILENT is the preferred package for power results. It was found that the total harmonic distortion limit for voltage in the simulated network exceeded an acceptable level. The harmonic mitigation solution chosen was to design a passive filter to decrease the distortion by shifting the resonance point of the network. The method to design the passive filter and its impact on efficiency and energy usage is included in the thesis. Unique power flow direction diagrams are developed as part of the methodology and form an essential step in the derivation of the new formulae. Efficiencies, power losses and energy usage at individual and combined frequencies were determined. Results showed the negative effects of harmonics on overall efficiency, energy usage and power losses of the system. The methodology and new formulae developed was found to be effective and their application is recommended for use by industry.

Orientador: Antonio Padilha Feltrin / Banca: Sergio Azevedo de Oliveira / Banca: José Aquiles Baesso Grimoni / Resumo: Neste trabalho investigou-se o desempenho de um algoritmo de cálculo de fluxo de potência trifásico baseado em um método de varredura chamado backward forward sweep. O estudo desenvolveu-se para sistemas de distribuição de energia elétrica radiais e/ou radiais fracamente malhados, sendo que o foco principal foi a avaliação do processo de convergência e exatidão do método de fluxo de potência. Para tal finalidade investigou-se variadas situações de redes, tais como: barras conectadas com linhas longas e linhas curtas, presença de reguladores de tensão, presença de geração distribuída, presença de linhas com representação shunt, sistemas com carregamento leve, carregamento médio e carregamento pesado, desequilíbrio de cargas entre as fases (a, b e c), influência de modelos de cargas (potência constante, admitância constante e corrente constante) etc. O método backward-forward sweep é bem conhecido e discutido na literatura, porém uma análise de desempenho com todos os detalhes de modelos existentes nas redes de distribuição não é encontrada. Encontram-se análises com modelos isolados, ou seja, considerando somente redes fracamente malhadas, ou com barras com tensão controlada, ou com modelos de transformadores etc. Muitos destes estudos apresentaram resultados apenas para redes de pequeno porte, pois na maioria dos casos o objetivo principal era validar os modelos. Neste trabalho buscou-se desenvolver um estudo completo de desempenho e confiabilidade de uma implementação do método backward-forward sweep. Assim foram utilizadas redes de distribuição reais e fictícias encontradas na literatura, com as mais variadas topologias, incluindo ramais monofásicos (MRT), diferentes níveis de carregamento, cargas desequilibradas e diversos modelos de componentes de rede. / Abstract: At this work an algorithm of calculation on three-phase power flow was investigated based on a sweeping method called backward forward sweep. The study was developed for radial electric power distribution networks and/or weakly interconnected radial ones, and the main focus was the evaluation of the convergence process and accuracy of the method of power flow. For such a purpose it was investigated varied situations of networks, such as: connected bars with long lines and short lines, voltage regulators presence, distributed generation presence, lines with representation shunt, systems with light, medium and heavy loading, unbalanced of loads among the phases (a, b and c) and influence of loads models (constant power, constant current and constant admittance). The method backward-forward sweep is very known and discussed in the literature, however an analysis with all the details of existent models in the distribution networks is not found. They are analyses with isolated models, in other words, considering only networks weakly interconnected, or with bars with controlled voltage, or with models of transformers. Many of these studies presented resulted just for networks of small load, because in most of the cases the main objective was to validate the models. In this work it was looked for to develop a complete study and reliability of an implementation of the method backward-forward sweep. Like this real and fictitious distribution networks were used found in the literature, with the most varied topologies, including monophase extensions (MRT), different loading levels, unbalanced loads and several models of networks components. / Mestre

M.Ing. / This study investigates the limits to which distortion can be compensated in electrical distribution networks. Many factors hinder the "ideal" compensation of the line current to a perfect sinusoidal, in phase, scaled replica of the supply voltage. The different power theories that can be used to derive the reference compensation current, is one of the fundamental limits. The differences and correspondences between the FBD and Czarnecki theories are investigated in detail. Furthermore, it is shown by simulation and practical results, that the effectivity of compensation by the instantaneous power theory is load dependent. The compensation strategy and topology also impose limits on the effectivity of compensation. The position and strategy of a compensator determine whether the consumer is able to isolate his distortion from the rest of the network, or isolate himself from the distortion of other consumers. Distortion frequencies and system impedances are chosen specifically to visually show the effect of the different topologies and strategies, by means of simulation. One of the most important limits brought about by new technology, is the lagging of the reference compensation current, due to the use of signal processing in determining the reference signals. The effect of this lagging reference is clearly shown by means of simulation and practical compensation systems. An effectivity index for this phenomenon is defined for steady state systems. The dynamic limitations of this lagging reference compensation current is investigated thoroughly. A method is derived by which the maximum fault, due to the sampling time and signal processing time, can be calculated when a high f-region occurs in the line current. The dynamic response of the compensation system is also limited by the ' di-ability of the converter. Therefore, a method is developed to calculate the individual fault contribution of the lagging reference as well as the converter. This method enables designers to determine the parameters of the signal processing system and the converter in the planning phase. The use of a maximum sampling frequency is stressed. In the experimental work, a 10kVA, PWM-switched IGBT inverter is used as a parallel voltage fed compensator. It compensates for two non-linear loads : a three phase diode rectifier with an inductive load, and a three phase diode rectifier with a capacitive load. The practical compensation according to the instantaneous power theory of these two loads, confirms that the result of this compensation is load dependent. The effect of the lagging reference compensation current in a practical system is also shown.

Intrabuilding power distribution circuits offer a number of unique advantages for local area networking. To enable the selection of proper error-control codes and protocols for reliable data communication services, error pattern statistics of intrabuilding power line channels are obtained. Also, error-causing disturbances are identified and their relationships to specific types of error patterns are determined. It is found that error occurrence is highly periodic, with periodicity being a function of the power line frequency which is nominally 60Hz in North America. Furthermore, results indicate that error pattern behaviour is relatively insensitive to communication carrier frequency and modulation schemes. Based on the measurement results, hybrid ARQ with bit-interleaving is suggested for reliable data transmission at high data rate (19,200bps). Burst error correcting codes can be used to reduce decoder cost and complexity with some sacrifices in performance. At lower data rates (1,200bps or below), effective error control can be accomplished more easily. Finally, the attenuation characteristics of a number of typical power line channels are presented. It is found that high frequency bypass can be used to improve signal transmission between different phases of the distribution transformer. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate