Atualmente, a intensidade de campo elétrico, campo magnético e campo eletromagnético é um fator determinante não só para a implantação de novas instalações, mas também, para as instalações existentes no sistema elétrico. Apesar de não existir nenhum estudo conclusivo que comprove a evidência direta entre a exposição a estes campos e os efeitos nocivos na saúde das pessoas, muitos países, inclusive o Brasil, definiram em suas legislações limites básicos à exposição de campos elétrico e magnético provenientes dos sistemas elétricos. Este trabalho tem como objetivo contribuir para análise de campo magnético de linhas subterrâneas de alta tensão existentes ou linhas em fase inicial de projeto, visando atender os limites de exposição vigentes na legislação local. Nele é apresentada a metodologia de cálculo de campo magnético baseada na Lei de Biot-Savart e no princípio da superposição. Estudos analíticos para verificação da influência dos parâmetros de instalação e elétricos de linhas sobre o campo magnético são apresentados para linhas subterrâneas de alta tensão compostas por um e dois circuitos com diferentes tipos de instalação e aterramentos. Comparações entre valores analíticos e valores de medições de campo magnético de linhas subterrâneas de alta tensão existentes em operação também são abordadas neste trabalho. As principais técnicas de mitigação de campo magnético utilizadas em linhas subterrâneas de alta tensão, tais como técnicas de compensação envolvendo laços de cabos e técnicas de blindagens com materiais metálicos externos aos cabos, também são apresentadas. Devido ao campo elétrico externo ao cabo isolado ser praticamente zero, assuntos referentes a este campo não são abordados neste trabalho. Por simplicidade, campo magnético refere-se à densidade de fluxo magnético neste documento. / Nowadays, the intensity of electric field, magnetic field and electromagnetic field is a determining factor, not only for implantation of new installations, but also for existing installations in the power system. Although no exist conclusive study that proves the direct evidence between exposure to these fields and adverse effects on human health, many countries, including Brazil, have defined in their laws basic limits for exposure to electric and magnetic fields produced by the electric system. This work aims to contribute to analysis of magnetic field for both existing high voltage underground lines and lines in initial stage of project, aiming the actual exposure limits of the local legislation. In it, is shown the magnetic field calculation methodology based on the Biot-Savart\'s law and the superposition principle. Analytical studies to verify the influence of installation and electrical parameters of lines on the magnetic field are presented for high voltage underground lines consist of one and two circuits with different types of installation and earthing. Comparisons between analytical and measurement values of magnetic field of existing high voltage underground lines in operation are also addressed in this work. The main mitigation techniques of magnetic field used in high voltage underground lines, such as compensation techniques by loop of cables and shielding by metallic materials, are also presented. Due the electric field outside the insulated cable be practically zero, issues related to the electric field are not addressed in this work. For simplicity, the magnetic field refers to the magnetic flux density in this document.

Recent years have seen a growing tendency that a large number of generators are connected to the electricity distribution networks, including renewables such as solar photovoltaics, wind turbines and biomass-fired power plants. Meanwhile, on the demand side, there are also some new types of electric loads being connected at increasing rates, with the most important of them being the electric vehicles (EVs). Uncertainties both from generation and consumption of electricity mentioned above are thereby being introduced, making the management of the system more challenging. With the proportion of electric vehicle ownership rapidly increasing, uncontrolled charging of large populations may bring about power system issues such as increased peak demand and voltage variations, while at the same time the cost of electricity generation, as well as the resulting Greenhouse Gases (GHG) emissions, will also rise. The work reported in this PhD Thesis aims to provide solutions to the three significant challenges related to EV integration, namely voltage regulation, generation cost minimisation and GHG emissions reduction. A novel, high-resolution, bottom-up probabilistic EV charging demand model was developed, that uses data from the UK Time Use Survey and the National Travel Survey to synthesise realistic EV charging time series based on user activity patterns. Coupled with manufacturers' data for representative EV models, the developed probabilistic model converts single user activity profiles into electrical demand, which can then be aggregated to simulate larger numbers at a neighbourhood, city or regional level. The EV charging demand model has been integrated into a domestic electrical demand model previously developed by researchers in our group at the University of Edinburgh. The integrated model is used to show how demand management can be used to assist voltage regulation in the distribution system. The node voltage sensitivity method is used to optimise the planning of EV charging based on the influence that every EV charger has on the network depending on their point of connection. The model and the charging strategy were tested on a realistic "highly urban" low voltage network and the results obtained show that voltage fluctuation due to the high percentage of EV ownership (and charging) can be significantly and maintained within the statutory range during a full 24-hour cycle of operation. The developed model is also used to assess the generation cost as well as the environmental impact, in terms of GHG emissions, as a result of EV charging, and an optimisation algorithm has been developed that in combination with domestic demand management, minimises the incurred costs and GHG emissions. The obtained results indicate that although the increased population of EVs in distribution networks will stress the system and have adverse economic and environmental effects, these may be minimised with careful off-line planning.

O presente trabalho tem como objetivo propor uma metodologia para avaliar o impacto das diversas técnicas de repotenciação no desempenho de linhas de transmissão em regime permanente, visto que na atual literatura não existe uma análise abrangente que possa ser aplicada em qualquer linha de transmissão carente de repotenciação. A metodologia busca fornecer subsídios para escolha da técnica mais vantajosa para repotenciar uma linha, utilizando de forma extensiva, os fatores de desempenho, e de forma sintetizada, os índices de mérito agregado, que, avaliados individualmente e/ou em conjunto, propiciam informações qualificadas para as conclusões técnicas. Destaca-se que a proposição dos fatores de desempenho e dos índices de mérito são as principais contribuições deste trabalho. Para complementar a metodologia, uma análise de curtos-circuitos foi proposta. Os resultados da utilização da metodologia foram positivos, possibilitando verificar os ganhos de potência na transmissão de energia. Vale destacar a eficiência dos índices de mérito agregado, que identificaram a melhor técnica de repotenciação de forma sintetizada, resguardando a qualidade e enquadramento dos resultados nas normas regulamentadoras. / This work aims at proposing a methodology to assessing the impact of power upgrade techniques on the steady-state performance of transmission lines, since there is not anything similar to this in the technical literature. The proposed methodology aims at providing technical information to subside the choice of the best power line upgrade technique, by the extensive application of the performance factors and of the aggregate merit indices. It must be pointed out that the proposition of the performance factors and of the aggregate merit indices are the main contributions of this work. Additionally, a short circuit analysis was also proposed to assess the power upgrade techniques. The results after the method application were satisfactory and allowed verifying the surplus of power related to each upgrade technique. The contribution of the aggregate merit indices was very important to identifying the most favorable upgrade technique in a simple way, so that all statutory technical limits were not violated.

O objetivo deste trabalho é estudar a identificação, classificação, localização e setorização de faltas em redes de distribuição radiais, verificar a maneira de aplicar e integrar diversas ferramentas numéricas convencionais, assim como ferramentas de sistemas inteligentes, visando identificar a ocorrência de uma falta, classificar as fases envolvidas com a mesma, e aplicar as diversas ferramentas existentes a fim de localizar em tempo real o eventual local onde houve a ocorrência da falta, permitindo que a mesma possa ser setorizada dentro do sistema da concessionária e informada ao centro de operações, usando uma nova abordagem inteligente baseada em análise espectral de sinais. / The aim of this work is study the identification, classification, location and sectorization of a fault in distribution radial networks, check how to implement and integrate various conventional numerical tools, as well as intelligent systems based tools, to identify the occurrence of a fault, classify the phases involved with it, and apply the various tools available to locate the place where a fault was occurred in real time, enabling it to be sectorized into the utility system and informed to operational center using a new intelligent approach based on spectral signals analysis.

Esta dissertação trata do problema de projeto e fortalecimento de sistemas de medição, para efeito de estimação de estado em sistemas elétricos de potência. São dois os objetivos principais desta dissertação. O primeiro é o desenvolvimento e implementação, em computador, de uma metodologia para projeto e fortalecimento de sistemas de medição confiáveis que fazem uso de medidas convencionais obtidas pelo sistema SCADA e de medidas fasoriais sincronizadas. Haja vista a existência de medidas redundantes que apresentam a característica de não refletirem grande parcela de seus erros nos resíduos do estimador por mínimos quadrados ponderados, definidas em (BENEDITO et al., 2013) como medidas com elevado índice UI, o segundo objetivo desta dissertação é o desenvolvimento e implantação, em computador, de uma metodologia para projeto e fortalecimento de sistemas de medição confiáveis que, além de considerar os critérios técnicos de confiabilidade para efeito de estimação de estado, considere também o índice UI das medidas. A metodologia possibilita a obtenção de sistemas de medição confiáveis formados por medidas com índice UI baixo. Para o desenvolvimento das metodologias propostas são utilizados como base algoritmo evolutivo monobjetivo e o método para projeto de sistemas de medição que faz uso da chamada matriz HΔT, que é obtida via um processo de fatoração triangular da matriz jacobiana transposta do estimador de estado por mínimos quadrados ponderados. / This thesis focuses on the problem of metering system planning for state estimation purposes and has two main objectives. The first one is to develop a methodology for metering system planning that allows the project of reliable metering systems considering both conventional and synchronized phasor measurements. Because of the existence of redundant measurements that have the characteristics of not reflecting their errors into the residuals of the weighted least squares estimator, called in (BENEDITO et al., 2013) as measurements with high Undetectability Index (UI), the second objective of this thesis is to develop a methodology, for metering system planning, that allow the project of reliable metering systems formed by measurements with UI lower than a pre-specified value. The background to develop the proposed methodologies are evolutionary algorithms and the method to metering system planning based on the analysis of the HΔt matrix, that is obtained from the triangular factorization of the transpose Jacobian matrix of the weighted least squares estimator.

<p>As space exploration vehicles travel deeper into space, their distance to earth increases.The increased communication delays and ground personnel costs motivatea migration of the vehicle health management into space. A way to achieve thisis to use a diagnosis system. A diagnosis system uses sensor readings to automaticallydetect faults and possibly locate the cause of it. The diagnosis system usedin this thesis is a model-based reasoning tool called RODON developed by UptimeSolutions AB. RODON uses information of both nominal and faulty behavior ofthe target system mathematically formulated in a model.The advanced diagnostics and prognostics testbed (ADAPT) developed at theNASA Ames Research Center provides a stepping stone between pure researchand deployment of diagnosis and prognosis systems in aerospace systems. Thehardware of the testbed is an electrical power system (EPS) that represents theEPS of a space exploration vehicle. ADAPT consists of a controlled and monitoredenvironment where faults can be injected into a system in a controlled manner andthe performance of the diagnosis system carefully monitored. The main goal of thethesis project was to build a model of the ADAPT EPS that was used to diagnosethe testbed and to generate decision trees (or trouble-shooting trees).The results from the diagnostic analysis were good and all injected faults thataffected the actual function of the EPS were detected. All sensor faults weredetected except faults in temperature sensors. A less detailed model would haveisolated the correct faulty component(s) in the experiments. However, the goal wasto create a detailed model that can detect more than the faults currently injectedinto ADAPT. The created model is stationary but a dynamic model would havebeen able to detect faults in temperature sensors.Based on the presented results, RODON is very well suited for stationary analysisof large systems with a mixture of continuous and discrete signals. It is possibleto get very good results using RODON but in turn it requires an equally goodmodel. A full analysis of the dynamic capabilities of RODON was never conductedin the thesis which is why no conclusions can be drawn for that case.</p><p> </p>

Orientador: Laurence Duarte Colvara / Banca: Percival Bueno de Araujo / Banca: Geraldo Caixeta Guimarães / Resumo: Os efeitos de compensação série em uma linha de transmissão sobre a potência sincronizante entre máquinas de um sistema de energia elétrica são considerados mediante análises da matriz admitância de barra, focando as admitâncias de transferência entre máquinas. Com este propósito, faz-se a redução da matriz que descreve a rede às barras internas das máquinas, preservando, no entanto, os efeitos da ação do compensador na capacidade de sincronização entre máquinas do sistema, definindo o Coeficiente de Eficácia e o Fator de Efeito da compensação sobre a admitância de transferência. Alguns estudos de casos foram efetuados com a finalidade de observar o comportamento do Fator de Efeito, visando, além de validar sua utilização para descrever o desempenho do sistema de potência com atuação de um TCSC, considerar sua habilidade em discriminar ligações entre máquinas que são mais severamente afetadas pela compensação série de outras que são pouco ou nada afetadas. Embora os testes tenham sido aplicados a sistemas exemplo de pequeno porte, os resultados obtidos são promissores / Abstract: The main concern lies in the TCSC action installed in a multimachine power system. The device effects upon the synchronizing power are taken into account by means of bus admittance matrix, focusing the intermachine transfer admittances. Since the purpose is to analyze the transfer admittances between machines, the bus admittance matrix is reduced to the machines internal busses preserving the compensator action effects by means of coefficients defined in order to evaluate the effectiveness and effect of the device action upon the intermachines synchronizing capacity. Some cases were evaluated in order to observe the effectiveness coefficient and effect factor as a power system performance descriptor with a TCSC action. The ability of the effect factor in pointing out intermachines connections that are more or less affected by the compensator is investigated. Although tests were applied to small sample systems, the obtained results are considered very promising / Mestre

Orientador: Percival Bueno de Araujo / Banca: Anna Diva Plasencia Lotufo / Banca: George Lauro Ribeiro de Brito / Resumo: Este trabalho apresenta estudos referentes à estabilidade a pequenas perturbações do SEP, considerando a atuação de FACTS para o amortecimento das oscilações eletromecânicas de baixa frequência. São abordados os dispositivos FACTS TCSC (Thyristor Controlled Series Capacitor) e o SSSC (Static Synchronous Series Compensator). É realizada a representação e modelagem dos dispositivos FACTS no SEP inserindo no Modelo Sensibilidade de Potência. Para melhorar o desempenho do SEP no que se refere à estabilidade a pequenas perturbações, controladores suplementares são propostos para aumentar o desempenho dos dispositivos TCSC e SSSC, introduzindo o amortecimento necessário ao SEP. Adicionam-se os controladores suplementares POD no modelo modificado para os dispositivos TCSC e SSSC para verificar sua atuação. Para encontrar a melhor localização para instalação dos dispositivos é usado a teoria dos resíduos. Esta mesma teoria é usada também para o ajuste dos parâmetros dos controlares juntamente com outro ajuste feito através de Redes Neurais Artificiais (RNA), que é proposto como alternativa de comparação ao método dos resíduos. Simulações são efetuadas em um sistema teste simétrico para se verificar resultados e a eficácia do controlador POD (parâmetros ajustados pela RNA proposta), acoplados aos dispositivos FACTS, na manutenção da estabilidade a pequenas perturbações do SEP. Palavras-chave: Controladores POD. Estabilidade de sistema de potência. Redes neurais artificiais. TCSC e SSSC / Abstract: This work presents studies referred to short term Electric Power System (EPS) perturbations, considering the actuation of FACTS devices for low frequency electromechanical oscillation damping. The devices considered are: FACTS TCSC (Thyristor Controlled Series Capacitor) and the SSSC (Static Synchronous Series Compensator). It is representation and modeling FACTS devices in the EPS inserting in the Power Sensitivity Model. To improve the performance of the EPS considering the short term perturbations, additional controllers are proposed to increase the performance of the TCSC and SSSC devices, introducing the necessary damping to the EPS. The additional POD controller is added to the modified model for TCSC and SSSC devices to verify the acting. The residual theory is used to find the best location to install the devices. The same theory is used to adjust the parameters of the controllers and an adjustment with Artificial Neural Networks (ANN) is proposed as an alternative to the residual method. Simulations are effectuated for a symmetric test system to verify the efficiency of the POD controller (parameters adjusted by the ANN proposed), coupled with the FACTS devices, to maintain the stability considering the short term perturbations / Mestre

This research proposes, implements and analyses a novel framework for multiobjective optimisation through evolutionary computing aimed at, but not restricted to, real-world problems in the engineering design domain. Evolutionary algorithms have been used to tackle a variety of non-linear multiobjective optimisation problems successfully, but their success is governed by key parameters which have been shown to be sensitive to the nature of the particular problem, incorporating concerns such as the number of objectives and variables, and the size and topology of the search space, making it hard to determine the best settings in advance. This work describes a real-encoded multi-objective optimising evolutionary algorithm framework, incorporating a genetic algorithm, that uses self-adaptive mutation and crossover in an attempt to avoid such problems, and which has been benchmarked against both standard optimisation test problems in the literature and a real-world airfoil optimisation case. For this last case, the minimisation of drag and maximisation of lift coefficients of a well documented standard airfoil, the framework is integrated with a freeform deformation tool to manage the changes to the section geometry, and XFoil, a tool which evaluates the airfoil in terms of its aerodynamic efficiency. The performance of the framework on this problem is compared with those of two other heuristic MOO algorithms known to perform well, the Multi-Objective Tabu Search (MOTS) and NSGA-II, showing that this framework achieves better or at least no worse convergence. The framework of this research is then considered as a candidate for smart (electricity) grid optimisation. Power networks can be improved in both technical and economical terms by the inclusion of distributed generation which may include renewable energy sources. The essential problem in national power networks is that of power flow and in particular, optimal power flow calculations of alternating (or possibly, direct) current. The aims of this work are to propose and investigate a method to assist in the determination of the composition of optimal or high-performing power networks in terms of the type, number and location of the distributed generators, and to analyse the multi-dimensional results of the evolutionary computation component in order to reveal relationships between the network design vector elements and to identify possible further methods of improving models in future work. The results indicate that the method used is a feasible one for the achievement of these goals, and also for determining optimal flow capacities of transmission lines connecting the bus bars in the network.

[pt] Este trabalho foca a política adotada em 2009 no Brasil para a contratação de energia eólica via leilões e seus impactos na decisão de investimento. Dividida em três partes conectadas entre si, esta tese primeiro discute as políticas de incentivo à energia eólica já adotadas no Brasil e em outros países, os benefícios e dificuldades da inserção eólica, identificando os problemas da atual política e propondo alterações. Na segunda parte, analisa-se a decisão sobre que quantidade ofertar em leilões de energia eólica no Brasil, e a que preço, considerando-se o risco do vento e as regras específicas para o segmento eólico adotadas em 2009. Usa-se como critério de decisão a medida Ômega (KEATING & SHADWICK, 2002), medida de risco ainda pouco disseminada no mundo corporativo e em especial no segmento eólico. Conclui-se que o setor tem incentivos para participar dos leilões ofertando um pouco mais que a geração esperada do projeto, haja vista que as regras são assimétricas para as situações em que o projeto está desempenhando abaixo ou acima do esperado. O resultado é útil para legisladores e para potenciais investidores em geração eólica no Brasil. Finalmente, considerando-se que alguns projetos de menor potencial eólico sobrepujaram outros de maior viabilidade econômica no leilão, a terceira parte deste trabalho procura identificar até que ponto o cenário incerto e as diferentes visões sobre o futuro podem ter favorecido este resultado. Supondo-se que ganhadores e perdedores do leilão apresentam assimetrias não só em termos do investimento necessário para entrar no mercado e no valor de seus projetos-padrão, mas também na forma como prevêem que o mercado para energia eólica evoluirá no Brasil, a tese analisa este problema à luz da teoria de Jogos com Opções Reais, avaliando a decisão de investir em projetos eólicos em ambiente de incerteza e sob os efeitos de competição. Mais especificamente, usa-se como referencial teórico os trabalhos de Huisman (2001) e Pawlina & Kort (2006) para duopólios assimétricos, estendendo-os de modo a considerar três assimetrias: assimetria no investimento necessário para entrar no mercado, no fluxo de valor de cada jogador (representado pelo valor dos projetos-padrão que comporão o portfólio de cada jogador), assimetria no processo estocástico utilizado para caracterizar as perspectivas futuras para os projetos eólicos. Análises de sensibilidade do modelo aos parâmetros identificam as situações limite em que se passa a favorecer a entrada no mercado de projetos menos viáveis economicamente e, portanto, com menores chances de serem concretizados. Conclui-se que pequenas discrepâncias na visão de futuro podem ter deixado de fora do leilão empresas com maiores chances de materializarem seus projetos. O risco de preempção de empresas menos viáveis cai quando há menos informação sobre as crenças dos concorrentes, porém ao custo de preços de energia um pouco mais elevados para os consumidores. Observa-se que quando há baixa incerteza e similaridade de crenças, fruto de política governamental mais clara, favorece-se tanto uma tarifa baixa de energia quanto uma indústria eólica mais forte no Brasil. / [en] This dissertation focuses on the governmental policy adopted in 2009 to contract wind power energy in Brazil through auctions and its impacts on the decision to invest in the wind power industry, and is organized into three separate but interconnected studies. The first study discusses the incentive policies adopted in Brazil and worldwide and the benefits and difficulties of increasing the stake of wind power in the country, identifying potential problems in the current policy and proposing changes. In the second part, the decision on the optimal amount of power to offer at auctions - and at what price - is analyzed based on the wind risk at the project’s site and on the specific rules for wind power in Brazil that were prevailing in 2009. For this purpose, the Omega measure (KEATING & SHADWICK, 2002) was adopted as decision criterion. The use of the Omega measure is still new to the corporate world and has not yet been used in the wind industry. The main conclusion is that entrepreneurs have incentives to sell slightly more than the expected output of the wind farm, given that the purchasing rules are asymmetric for situations in which a farm is underperforming or is above expectations. This result is useful for legislators and potential investors in wind power generation in Brazil. Finally, considering that some projects with lower wind potential have won over others with higher potential, the third part of this work attempts to identify to what extent the uncertain scenario and investors’ different outlooks of the market’s potential may have influenced this result. Assuming that losers and winners of the auction had asymmetries not only in terms of the investments necessary to enter the market and build their portfolio of wind farms, but also in terms of their views on how the market for wind power will evolve in Brazil, this dissertation analyses this problem in light of the Option-Games Theory, deriving the decision to invest in wind projects under uncertainty and competition. The theoretical frameworks of this analysis are the works by Huisman (2001) and Pawlina & Kort (2006) for asymmetric duopolies, extending their theory to consider three asymmetries: asymmetry in the investment to enter the market, in the value of each player’s portfolio, and asymmetry in the stochastic process adopted by each player to describe the market prospects for wind farms. A sensitivity analysis to the parameters of the model identified the thresholds above which less viable firms preempt the market. The main conclusion is that minor asymmetries in the views about the future may have been sufficient to make more viable firms quit the auction earlier. The risk of less viable firms preempting the market drops when their opponent’s beliefs are not known, but at the expense of higher energy prices for consumers. When uncertainty is low and beliefs are symmetric, a feasible scenario when the governmental policy for the sector is clearer, the result can be lower energy tariffs as well as a stronger wind industry in Brazil.