Devido à alta demanda energética e a grande complexidade dos atuais Sistemas Elétricos de Potência (SEPs), altamente interligados, torna-se cada vez mais importante para o operador do sistema, conhecer o estado atual do SEP. Além disso, dispor de ferramentas que permitam prever situações que venham a comprometer o bom funcionamento do sistema. Como um bom funcionamento, enquadra-se a continuidade do suprimento e perfis adequados de tensão elétrica, mesmo após a ocorrência de perturbações, o que pode ser afetado pelo fenômeno de instabilidade de tensão (ou colapso de tensão). Por isso, o objetivo deste trabalho é desenvolver uma metodologia de análise do colapso de tensão em tempo real considerando limites de potência ativa e reativa de geradores, a qual visa auxiliar o operador do sistema. Esta metodologia é dividida em cinco etapas. A primeira delas consiste em uma análise do caso base dos SEPs considerados, utilizando um algoritmo que permite estimar a margem de estabilidade de tensão do sistema, considerando os limites de potência ativa e reativa dos geradores. Esta primeira etapa utiliza a metodologia de fluxo de potência continuado, utilizando a carga e a tensão como parâmetros de continuação. A segunda etapa apresenta uma análise de contingências rápida considerando contingências simples de linhas de transmissão, seguindo o critério N-1. Nesta segunda etapa, foi utilizado o método de Look Ahead Modificado. A terceira etapa é uma análise apurada das contingências mais críticas, identificadas na etapa dois, a fim de verificar a presença de bifurcações induzidas por limites. Nesta terceira etapa, também se utilizou a metodologia de fluxo de potência continuado. Na quarta etapa, são aplicados todos os controle disponíveis no sistema, como inserção de banco de capacitores e ajuste do TAP dos transformadores, a fim de verificar qual seria o impacto dessas ações de controle no limite de operação segura do sistema, utilizando o método de Look Ahead Modificado. Essas quatro etapas possibilitam uma análise da estabilidade de tensão do sistema em tempo real. Por fim, é proposta uma quinta etapa de análise de contingências Offline, sendo uma análise mais precisa de todas as contingências, utilizando a metodologia de fluxo de potência continuado. Os SEPs analisados nesta dissertação foram o sistema de cinco barras Stagg, o sistema de quatorze barras padrão do Institute of Electrical and Electronics Engineers (IEEE) e o sistema de trinta barras padrão IEEE. / Due to the high energy demand and the high complexity of today's interconnected Electrical Power Systems (SEPs), it is becoming increasingly important for the system operator to know the current state of the SEP. In addition, have the tools to predict situations that may compromise the smooth operation of the system. As a good operation, the continuity of the supply and adequate voltage profiles are correct, even after the occurrence of disturbances, which can be affected by the phenomenon of voltage instability (or voltage collapse). Therefore, the objective of this work is to develop a methodology for the analysis of voltage collapse in real time considering the limits of active and reactive power of generators, which aims to assist the system operator. This methodology is divided into five steps. The first one consists of an analysis of the base case of the considered SEPs, using an algorithm that allows estimating the voltage stability margin of the system considering the limits of active and reactive power of the generators. This first step uses the continuous power flow methodology, using load and voltage as continuation parameters. The second stage presents a fast contingency analysis considering simple contingencies of transmission lines, following the criterion N-1. In this second step, the Modified Look Ahead method was used. The third step is an accurate analysis of the most critical contingencies, identified in step two, in order to verify the presence of limits-induced bifurcations. In this third step, we also used the continuous power flow methodology. In the fourth step, all available system controls, such as capacitor bank insertion and TAP adjustment of the transformers, are applied in order to verify the impact of these control actions on the safe operation limit of the system, using the Look Ahead Modified. These four steps enable a real-time analysis of the voltage stability of the system. Finally, a fifth stage of analysis of Offline contingencies is proposed, and a more precise analysis of all the contingencies using the methodology of continuous power flow is proposed. The SEPs analyzed in this dissertation were the Stagg five-bar system, the Institute of Electrical and Electronics Engineers (IEEE) standard fourteen bar system and the IEEE standard thirty-bar system.

Orientador: Jose Sanches Mantovani / Resumo: Neste trabalho propõem-se metodologias para realizar o planejamento de sistemas de distribuição de energia elétrica de média tensão (MT), baixa tensão (BT) e o planejamento integrado de sistemas de média e baixa tensão (MT/BT). Nos modelos de funções objetivos considerados minimizam-se os custos associados à construção, expansão, operação e confiabilidade das redes de MT, BT e MT/BT, considerando a presença de geradores distribuídos e variáveis de natureza estocástica. A geração distribuída presente no planejamento de sistemas de distribuição é avaliada através de metodologias de geração de cenários e análise de risco. Como método de busca de soluções para o problema de planejamento dos sistemas de distribuição é proposta a meta-heurística de busca em vizinhança variável GVNS (General Variable Neighborhood Search). A meta-heurística GVNS trabalha com uma série de estruturas de vizinhanças que permitem explorar o espaço de busca de forma eficiente através dos critérios de diversificação e intensificação, aumentando a probabilidade de obter soluções que não sejam ótimos locais. No planejamento integrado MT/BT, as soluções obtidas são analisadas através de um fluxo de potência integrado entre as redes de MT e BT, considerando as relações de conexão dos transformadores entre estes sistemas. Os algoritmos propostos relacionados ao planejamento de sistemas MT, BT e MT/BT são implementados em linguagem de programação C++ e testado em diferentes sistemas testes de MT (54 barras e 182... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

Pour faire face aux mutations du paysage énergétique, les réseaux de distribution d'électricité sont soumis à des exigences de fonctionnement avec des indices de fiabilité à garantir. Dans les années à venir, de grands investissements sont prévus pour la construction des réseaux électriques flexibles, cohérents et efficaces, basés sur de nouvelles architectures et des solutions techniques innovantes, adaptatifs à l'essor des énergies renouvelables. En prenant en compte ces besoins industriels sur le développement des réseaux de distribution du futur, nous proposons, dans cette thèse, une approche reposant sur la théorie des graphes et l'optimisation combinatoire pour la conception de nouvelles architectures pour les réseaux de distribution. Notre démarche consiste à étudier le problème général de recherche d'une architecture optimale qui respecte l'ensemble de contraintes topologiques (redondance) et électrotechniques (courant maximal, plan de tension) selon des critères d'optimisation bien précis : minimisation du coût d'exploitation (OPEX) et minimisation de l'investissement (CAPEX). Ainsi donc, les deux familles des problèmes combinatoires (et leurs relaxations) ont été explorées pour proposer des résolutions efficaces (exactes ou approchées) du problème de planification des réseaux de distribution en utilisant une formulation adaptée. Nous nous sommes intéressés particulièrement aux graphes 2-connexes et au problème de flot arborescent avec pertes quadratiques minimales. Les résultats comparatifs de tests sur les instances de réseaux (fictifs et réels) pour les méthodes proposées ont été présentés. / To cope with the changes in the energy landscape, electrical distribution networks are submitted to operational requirements in order to guarantee reliability indices. In the coming years, big investments are planned for the construction of flexible, consistent and effective electrical networks, based on the new architectures, innovative technical solutions and in response to the development of renewable energy. Taking into account the industrial needs of the development of future distribution networks, we propose in this thesis an approach based on the graph theory and combinatorial optimization for the design of new architectures for distribution networks. Our approach is to study the general problem of finding an optimal architecture which respects a set of topological (redundancy) and electrical (maximum current, voltage plan) constraints according to precise optimization criteria: minimization of operating cost (OPEX) and minimization of investment (CAPEX). Thus, the two families of combinatorial problems (and their relaxations) were explored to propose effective resolutions (exact or approximate) of the distribution network planning problem using an adapted formulation. We are particularly interested in 2-connected graphs and the arborescent flow problem with minimum quadratic losses. The comparative results of tests on the network instances (fictional and real) for the proposed methods were presented.

Submitted by DIOGO RUPOLO null (rupolo.diogo@gmail.com) on 2017-09-08T14:50:14Z No. of bitstreams: 1 Tese Final Diogo Rupolo.pdf: 4125842 bytes, checksum: 60d451cc4d13afb90cca7e443d7436b1 (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-09-11T20:51:49Z (GMT) No. of bitstreams: 1 rupolo_d_dr_ilha.pdf: 4125842 bytes, checksum: 60d451cc4d13afb90cca7e443d7436b1 (MD5) / Made available in DSpace on 2017-09-11T20:51:49Z (GMT). No. of bitstreams: 1 rupolo_d_dr_ilha.pdf: 4125842 bytes, checksum: 60d451cc4d13afb90cca7e443d7436b1 (MD5) Previous issue date: 2017-08-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho propõem-se metodologias para realizar o planejamento de sistemas de distribuição de energia elétrica de média tensão (MT), baixa tensão (BT) e o planejamento integrado de sistemas de média e baixa tensão (MT/BT). Nos modelos de funções objetivos considerados minimizam-se os custos associados à construção, expansão, operação e confiabilidade das redes de MT, BT e MT/BT, considerando a presença de geradores distribuídos e variáveis de natureza estocástica. A geração distribuída presente no planejamento de sistemas de distribuição é avaliada através de metodologias de geração de cenários e análise de risco. Como método de busca de soluções para o problema de planejamento dos sistemas de distribuição é proposta a meta-heurística de busca em vizinhança variável GVNS (General Variable Neighborhood Search). A meta-heurística GVNS trabalha com uma série de estruturas de vizinhanças que permitem explorar o espaço de busca de forma eficiente através dos critérios de diversificação e intensificação, aumentando a probabilidade de obter soluções que não sejam ótimos locais. No planejamento integrado MT/BT, as soluções obtidas são analisadas através de um fluxo de potência integrado entre as redes de MT e BT, considerando as relações de conexão dos transformadores entre estes sistemas. Os algoritmos propostos relacionados ao planejamento de sistemas MT, BT e MT/BT são implementados em linguagem de programação C++ e testado em diferentes sistemas testes de MT (54 barras e 182 barras), BT (76 barras) e MT/BT (172 e 412 barras), sob diferentes cenários operacionais. / This work proposes methodologies for the planning of medium voltage (MV), low voltage (LV), and integrated planning of medium and low voltage (MV/LV) systems. In the objective function models are considered the costs associated with the construction, expansion, operation and reliability of MV, LV and integrated MV/LV networks. Distributed generators and stochastic variables are also considered in the models. The distributed generation present in the planning of distribution systems is evaluated through methodologies of scenario generation and risk analysis. As a method of finding solutions to the problem of distribution system planning, the GVNS metaheuristic (General Variable Neighborhood Search) is proposed. The metaheuristic GVNS works with a series of neighborhood structures that allow to explore the search space efficiently through diversification and intensification criteria, increasing the probability of obtaining solutions that are not local optimum. In integrated MV/LV planning, the solutions obtained are analyzed through an integrated power flow between the MV and LV networks, considering the connection ratios of the transformers between these systems. The proposed algorithms related to the planning of MV, LV and integrated MV/LV systems are implemented in C ++ programming language and tested in different distribution systems, MV (54 and 182 bus), LV (76 bus) and MV/LV (172 and 412 bus), under different operating scenarios.

A ocorrência de arborescências em água (water tree) ou elétrica (electrical tree) é apontada como o principal fenômeno de degradação em isolações sólidas de cabos de distribuição de energia elétrica. A evolução destas arborescências pode levar a camada de isolação à ruptura dielétrica e, como conseqüência, à falha destes equipamentos, com a interrupção do fornecimento de energia elétrica. O entendimento deste fenômeno é necessário para desenvolver métodos de análise e prevenção da ruptura de materiais isolantes. Este trabalho mostra a aplicação da técnica contraste de fase por raios X como metodologia para o estudo das arborescências formadas em materiais isolantes de borracha de propileno etileno (EPR) e polietileno reticulado (XLPE). / The water tree or electrical tree occurrence is identified as the main phenomena in the degradation in solid isolations of the electric energy distribution cables. The water tree evolution can lead to dielectric breakdown of the isolation layer and, consequently, to the failure this equipment and the interruption of the electric energy supply. The understanding this phenomenon is necessary for the development analysis methods and to prevent collapse in the polymeric insulation. This work demonstrates the application of X-ray phase contrast technique as a methodology for the study of the water tree and electrical tree in Ethylene propylene rubber (EPR) and crosslinked polyethylene (XLPE).

Redes inteligentes de distribuição de energia fornecem serviços com o potencial de aumentar a eficiência energética e a qualidade de vida da sociedade, mas possuem requisitos severos de tempo de resposta, confiabilidade, escalabilidade e QoS. As chaves ópticas são dispositivos comutadores de caminhos em fibras ópticas popularmente utilizados para trocas físicas de rotas. Neste trabalho sugere-se utilizar estes dispositivos para ativamente reorganizar uma rede com o objetivo de diminuir a latência de comunicação, visando atender aos requisitos de comunicações dos serviços de redes inteligentes. Foram estudadas as características de protocolos de roteamento conhecidos e aplicou-se o algoritmo de Dijkstra na criação de quatro heurísticas de otimização dos caminhos máximos em redes com chaves ópticas. Simulações realizadas mostram que as heurísticas propostas reduzem o número de saltos nos caminhos máximos, levando à redução de latência. É sugerida a continuação deste estudo aperfeiçoando as heurísticas propostas com outros mecanismos de otimização e diferentes métricas, como redução de congestionamento de tráfego e de consumo de energia na rede. / Smart grid networks provide services with the potential to increase energy efficiency and the quality of life of society, but have strict requirements regarding response time, reliability, scalability and QoS. The optical switches are fiber optic switching devices commonly used for physical route changing. In this study, it is suggested to use these devices to actively rearrange a network in order to reduce the communication latency, to meet the communications requirements of smart grid services. The characteristics of known routing protocols have been studied and the Dijkstra algorithm has been applied at the creation of four heuristics that aim to optimize the maximum paths in networks with optical switches. The simulations show that the heuristics reduce the maximum number of hops in the paths, leading to reductions in latency. It is suggested the continuation of this study improving the heuristics with other optimization engines and different metrics, such as reducing traffic congestion and energy.

Redes inteligentes de distribuição de energia fornecem serviços com o potencial de aumentar a eficiência energética e a qualidade de vida da sociedade, mas possuem requisitos severos de tempo de resposta, confiabilidade, escalabilidade e QoS. As chaves ópticas são dispositivos comutadores de caminhos em fibras ópticas popularmente utilizados para trocas físicas de rotas. Neste trabalho sugere-se utilizar estes dispositivos para ativamente reorganizar uma rede com o objetivo de diminuir a latência de comunicação, visando atender aos requisitos de comunicações dos serviços de redes inteligentes. Foram estudadas as características de protocolos de roteamento conhecidos e aplicou-se o algoritmo de Dijkstra na criação de quatro heurísticas de otimização dos caminhos máximos em redes com chaves ópticas. Simulações realizadas mostram que as heurísticas propostas reduzem o número de saltos nos caminhos máximos, levando à redução de latência. É sugerida a continuação deste estudo aperfeiçoando as heurísticas propostas com outros mecanismos de otimização e diferentes métricas, como redução de congestionamento de tráfego e de consumo de energia na rede. / Smart grid networks provide services with the potential to increase energy efficiency and the quality of life of society, but have strict requirements regarding response time, reliability, scalability and QoS. The optical switches are fiber optic switching devices commonly used for physical route changing. In this study, it is suggested to use these devices to actively rearrange a network in order to reduce the communication latency, to meet the communications requirements of smart grid services. The characteristics of known routing protocols have been studied and the Dijkstra algorithm has been applied at the creation of four heuristics that aim to optimize the maximum paths in networks with optical switches. The simulations show that the heuristics reduce the maximum number of hops in the paths, leading to reductions in latency. It is suggested the continuation of this study improving the heuristics with other optimization engines and different metrics, such as reducing traffic congestion and energy.

Legislation on benefit sharing dates back to 1992 and the commandment of the UNConvention on Biological Diversity, hence implementation still has few cases to fall back on(CBD, 1992). The case study of the project ProBenefit presented by the thesis highlights howlack of deliberation can undermine a democratic process. The objective of the thesis is thatProBenefit’s attempt to implement the standards of the CBD on access and benefit sharingwill highlight not only problems met by this specific project, but difficulties that generallymeet democratic processes in contexts of high inequality. To define if the project ProBenefitsucceeded in carrying out a deliberative process the project will be analyzed by the criteria:access to information, representation, legitimacy and involvement.The population in the project area of ProBenefit had a long history of social marginalization,which made it hard for foreign projects to gain legitimacy. The lack of independentorganizations and the late establishment of the project, which resulted in time shortage, madeit impossible to prevent the distrust of the local population. The failure of the projectcoordinators to ensure active participation of all stakeholders resulted in a late and lowinvolvement of the local participants. The absence of independent organization also madedemocratic legitimacy of the process questionable. Even if ProBenefit had a vision ofdemocratic deliberation the project was unable to break down the prevailing unequal powerdistribution which resulted in an unsustainable process and failure. The conclusion of thethesis is that the attainment of deliberation foremost depends on how a project deals with theexisting distribution of power and how it succeeds in involving all stakeholders.

Aujourd’hui les réseaux électriques sont exploités dans un marché dérégulé. Les gestionnaires des réseaux électriques sont tenus d’assurer un certain nombre de critères de fiabilité et de continuité du service, tout en minimisant le coût total consacré aux efforts effectués pour maintenir la fiabilité des installations. Il s’agit de trouver une stratégie, qui répond à plusieurs exigences, comme :le coût, les performances, la législation, les exigences du régulateur, etc. Cependant, le processus de prise de décision est subjectif, car chaque participant ramène sa contribution sur base de sa propre expérience. Bien que ce processus permette de trouver la « meilleure » stratégie, cette dernière n’est pas forcément la stratégie « optimale ». Ce compromis technico-économique a sensibilisé les gestionnaires des réseaux électriques à la nécessité d’un recours à des outils d’aide à la décision, qui doivent se baser sur des nouvelles approches quantitatives et une modélisation plus proches de la réalité physique.<p>Cette thèse rentre dans le cadre d’un projet de recherche lancé par ELIA, et dénommé COMPRIMa (Cost-Optimization Models for the Planning of the Renewal, Inspection, and Maintenance of Belgian power system facilities). Ce projet vise à développer une méthodologie qui permet de modéliser une partie du réseau électrique de transport (par les réseaux de Petri stochastiques) et de simuler son comportement dynamique sur un horizon donné (simulation de Monte Carlo). L’évaluation des indices de fiabilité permet de comparer les différents scénarios qui tentent d’améliorer les performances de l’installation. L’approche proposée est basée sur la stratégie RCM (Reliability-Centered Maintenance).<p>La méthodologie développée dans cette thèse permet une modélisation plus réaliste du réseau qui tient compte, entre autres, des aspects suivants :<p>- La corrélation quantitative entre le processus de maintenance et le processus de vieillissement des composants (par un modèle d’âge virtuel) ;<p>- Les dépendances liées à l’aspect multi-composant du système, qui tient compte des modes de défaillance spécifiques des systèmes de protection ;<p>- L’aspect économique lié à la stratégie de maintenance (inspection, entretien, réparation, remplacement), aux coupures (programmées et forcées) et aux événements à risque (refus disjoncteur, perte d’un client, perte d’un jeu de barres, perte d’une sous-station, etc.). / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

MSc (Statistics) / Department of Statistics / Forecasting of electricity peak demand levels is important for decision makers in Eskom. The overall objective of this study was to develop medium term load forecasting models which will help decision makers in Eskom for planning of the operations of the utility company. The frequency table of hourly daily demands was carried out and the results show that most peak loads occur at hours 19:00 and 20:00, over the period 2009 to 2013. The study used generalised additive models with and without tensor product interactions to forecast electricity demand at 19:00 and 20:00 including daily peak electricity demand. Least absolute shrinkage and selection operator (Lasso) and Lasso via hierarchical interactions were used for variable selection to increase the model interpretability by eliminating irrelevant variables that are not associated with the response variable, this way also over tting is reduced. The parameters of the developed models were estimated using restricted maximum likelihood and penalized regression. The best models were selected based on smallest values of the Akaike information criterion (AIC), Bayesian information criterion (BIC) and Generalized cross validation (GCV) along with the highest Adjusted R2. Forecasts from best models with and without tensor product interactions were evaluated using mean absolute percentage error (MAPE), mean absolute error (MAE) and root mean square error (RMSE). Operational forecasting was proposed to forecast the demand at hour 19:00 with unknown predictor variables. Empirical results from this study show that modelling hours individually during the peak period results in more accurate peak forecasts compared to forecasting daily peak electricity demand. The performance of the proposed models for hour 19:00 were compared and the generalized additive model with tensor product interactions was found to be the best tting model. / NRF