There are many calamitous events such as earthquakes, hurricanes, tsunamis etc. that occur suddenly and cause great loss of life, damage, or hardship. Hurricanes cause significant damage to power distribution systems, resulting in prolonged customer outages and excessive delays in the reconstruction efforts. Accordingly, predicting the effects of power outages on the performance of power distribution systems is of major importance to government agencies, utilities, and customers. Unfortunately, the current tools to predict the performance of power distribution systems during catastrophic events are limited in both the performance measures considered, as well as in their ability to model real systems. The main goal of this research is to develop a methodology for simulating hurricanes of different intensity on power distribution systems of small and medium size cities. Our study includes a detailed comparison between the engineering-based and connectivity-based models of power distribution systems, as well as the impact of power re-routing algorithms on the system reliability. Our approach is based on fragility curves that capture the ability of the system to withstand a range of wind speeds. In addition, we develop a multiscale approach that facilitates efficient computation of fragility curves for large cities. With this approach, hurricanes are simulated over small zones of a city and fragility curves are obtained. These are used to estimate the damage for identical zones throughout the city. To validate our techniques, two testbeds, Micropolis and Mesopolis, were used. Micropolis is synthetic model for a small city and Mesopolis for a big city. Obtained results have validated our approach and have shown that they can be used to effectively predict hurricane damage.

Στην παρούσα διπλωματική εργασία μελετήθηκαν οι αιτίες, οι επιπτώσεις και η αντιμετώπιση σε προβλήματα που αφορούν διείσδυση ανώτερων αρμονικών σε δίκτυο μέσης τάσης. Μοντελοποιήθηκε και εισήχθη ένα κομμάτι πραγματικού δικτύου μέσης τάσης στο υπολογιστικό πακέτο MATLAB. Ο εξαχθείσες προσομοιώσεις τόσο της εμπέδησης-συχνότητας όσο και της τάσης παρουσία αρμονικών, έδωσαν συμπεράσματα για τη συμπεριφορά του δικτύου. Τέλος εξετάστηκε η συμπεριφορά του παρουσία παθητικών φίλτρων. / In the present "Diploma Thesis" the causes,the effects and the treatment of high harmonics penetration in middle voltage electric distribution systems were studied.A real middle voltage electric distribution system was modeled with the use of Matlab.The simulations (impedance vs. frequency and voltage with presence of high harmonics) resulted conclusions over the behavior of such system.At last,the behavior of the electric distribution system in presence of passive filters was studied.

Made available in DSpace on 2014-06-11T19:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-24Bitstream added on 2014-06-13T18:41:00Z : No. of bitstreams: 1 ruedamedina_ac_dr_ilha.pdf: 2722738 bytes, checksum: 33ca19bfc424019d1195ad295d45dbab (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo principal deste projeto é o desenvolvimento de metodologias que indiquem os custos reais de determinados serviços ancilares de geradores distribuídos, e como podem contribuir, com estes serviços, para melhoria da qualidade do fornecimento de energia na distribuição, subtransmissão e até transmissão. Estas metodologias deverão fornecer os custos destes serviços, bem como os benefícios para o sistema elétrico, além de identificar quem e quanto oferece de cada serviço para a operação segura e dentro dos procedimentos preestabelecidos. Para o desenvolvimento dos algoritmos de solução são considerados dois tipos de geração distribuida: geradores distribuídos com variabilidade da fonte primária de energia mínima ou desprezível (microturbinas a gás, pequenas centrais hidrelétricas, geradores em usinas de açúcar e álcool, etc.), e geradores distribuídos que tem forte dependência das variações da fonte primária de energia (principalmente turbinas eólicas e sistemas fotovoltaicos). Este último grupo de geradores precisa de considerações mais elaboradas que incluam as incertezas na geração de energia. Este assunto é tratado através de Simulações de Monte Carlo, Cadeias de Markov e Lógica Fuzzy. Através das Simulações de Monte Carlo são realizados fluxos de potência probabilísticos em múltiplos cenarios, enquanto que com as Cadeias de Markov e a Lógica Fuzzy são descritas as séries de tempo relacionadas com a geração de potência ativa dos geradores distribuídos. Também sãoconsiderados vários objetivos a serem otimizados através de técnicas multiobjetivo, observando principalmente as perdas de potência nas linhas do sistema, os custos de geração dos geradores distribuídos e a estabilidade de tensão... / The main objective of this project is to develop methodologies to indicate the real costs of certain ancillary services when they are delivered by distributed generators, and how they can contribute, with these services, to improve the quality of power supply in distribution, subtransmission and even transmission systems. These methodologies should provide the costs of these services and benefits to the electrical system as a whole, and they should also identify who and how much of each service provides for the safe operation and within the pre-established procedures. Two types of distributed generation are considered for the development of solution algorithms: distributed generators with minimal or negligible variability of the primary energy source (gas micro-turbines, small hydroelectric plants, generators in sugar and alcohol plants, etc.), and distributed generators that have strong dependence on variations of the primary energy source (mainly wind turbines and photovoltaic systems). This latter group of generators need more elaborate considerations to include the uncertainties in power generation. This matter is addressed through Monte Carlo Simulations, Markov Chains and Fuzzy Logic. Through Monte Carlo Simulations probabilistic power flows in multiple scenarios are performed, while with Markov Chains and Fuzzy Logic the time series related to the active power generation of distributed generators are described. Several objectives are also considered to be optimized by multi-objective techniques, noting particularly the power losses in the lines of the system, generation costs of distributed generators and voltage stability of the system. The ancillary services considered in this work are reactive power support, reserves for frequency control and secondary frequency control. Reactive power support... (Complete abstract click electronic access below)

abstract: The deterioration of drinking-water quality within distribution systems is a serious cause for concern. Extensive water-quality deterioration often results in violations against regulatory standards and has been linked to water-borne disease outbreaks. The causes for the deterioration of drinking water quality inside distribution systems are not yet fully understood. Mathematical models are often used to analyze how different biological, chemical, and physical phenomena interact and cause water quality deterioration inside distribution systems. In this dissertation research I developed a mathematical model, the Expanded Comprehensive Disinfection and Water Quality (CDWQ-E) model, to track water quality changes in chloraminated water. I then applied CDWQ-E to forecast water quality deterioration trends and the ability of Naegleria fowleri (N.fowleri), a protozoan pathogen, to thrive within drinking-water distribution systems. When used to assess the efficacy of substrate limitation versus disinfection in controlling bacterial growth, CDWQ-E demonstrated that bacterial growth is more effectively controlled by lowering substrate loading into distribution systems than by adding residual disinfectants. High substrate concentrations supported extensive bacterial growth even in the presence of high levels of chloramine. Model results also showed that chloramine decay and oxidation of organic matter increase the pool of available ammonia, and thus have potential to advance nitrification within distribution systems. Without exception, trends predicted by CDWQ-E matched trends observed from experimental studies. When CDWQ-E was used to evaluate the ability N. fowleri to survive in finished drinking water, the model predicted that N. fowleri can survive for extended periods of time in distribution systems. Model results also showed that N. fowleri growth depends on the availability of high bacterial densities in the 105 CFU/mL range. Since HPC levels this high are rarely reported in bulk water, it is clear that in distribution systems biofilms are the prime reservoirs N. fowleri because of their high bacterial densities. Controlled laboratory experiments also showed that drinking water can be a source of N. fowleri, and the main reservoir appeared to be biofilms dominated by bacteria. When introduced to pipe-loops N. fowleri successfully attached to biofilms and survived for 5 months. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2010

abstract: Nowadays there is a pronounced interest in the need for sustainable and reliable infrastructure systems to address the challenges of the future infrastructure development. This dissertation presents the research associated with understanding various sustainable and reliable design alternatives for water distribution systems. Although design of water distribution networks (WDN) is a thoroughly studied area, most researchers seem to focus on developing algorithms to solve the non-linear hard kind of optimization problems associated with WDN design. Cost has been the objective in most of the previous studies with few models considering reliability as a constraint, and even fewer models accounting for the environmental impact of WDN. The research presented in this dissertation combines all these important objectives into a multi-objective optimization framework. The model used in this research is an integration of a genetic algorithm optimization tool with a water network solver, EPANET. The objectives considered for the optimization are Life Cycle Costs (LCC) and Life Cycle Carbon Dioxide (CO2) Emissions (LCE) whereby the system reliability is made a constraint. Three popularly used resilience metrics were investigated in this research for their efficiency in aiding the design of WDNs that are able to handle external natural and man-made shocks. The best performing resilience metric is incorporated into the optimization model as an additional objective. Various scenarios were developed for the design analysis in order to understand the trade-offs between different critical parameters considered in this research. An approach is proposed and illustrated to identify the most sustainable and resilient design alternatives from the solution set obtained by the model employed in this research. The model is demonstrated by using various benchmark networks that were studied previously. The size of the networks ranges from a simple 8-pipe system to a relatively large 2467-pipe one. The results from this research indicate that LCE can be reduced at a reasonable cost when a better design is chosen. Similarly, resilience could also be improved at an additional cost. The model used in this research is more suitable for water distribution networks. However, the methodology could be adapted to other infrastructure systems as well. / Dissertation/Thesis / Ph.D. Construction 2012

Neste trabalho apresentar-se-à um novo método para a localização de faltas em Sistemas de Distribuição de Energia Elétrica. Este combina duas técnicas, uma baseada na Impedância Aparente e outra nas Ondas Viajantes. A técnica de localização por impedância aparente utiliza o sinal armazenado pelo relé, analisando-o na sua frequência fundamental. O resultado desta análise é a estimativa da distância da falta. Esta representa a distância elétrica desde o rele até a falta, o que em sistemas de distribuição radiais, com laterais, pode gerar mais de uma resposta como certa. A técnica das ondas viajantes é utilizada para a localização da seção faltosa utiliza os sinais de alta frequência presentes no sinal. O resultado desta análise é a estimativa da seção onde ocorreu a falta. Assim, estas duas técnicas complementam-se para fornecer a posição da falta. / This work presents a new hybrid method to Fault Location in Power Distribution Systems. This work combines two techniques, one based on Apparent Impedance and the other based on Traveling Waves. Apparent Impedance based methods use the signals stored in the relay. That signals are analyzed in their fundamental frequency. It is obtained as result the distance from sub-station to the fault. This distance represents the electrical distance from the sending end to the fault, but in Power Distribution Systems with several laterals these fault location could be more than one. The Traveling waves method use the high frequencies presents in faulted signals. Obtain with this the faulted section. Thus both techniques are complements, resulting in only one distance to the fault point.

As metodologias de análise de curto-circuito aplicadas a sistemas elétricos de potência apresentaram uma considerável evolução ao longo do último século e foram desenvolvidas inicialmente para o estudo de faltas em sistemas de transmissão de energia elétrica. Estes sistemas possuem características equilibradas e utilizam o método de componentes simétricas para a estimativa do estado do sistema no período durante a falta. O emprego deste método para a determinação das correntes de cur-tos-circuitos em sistemas desequilibrados, por requerer simplificações e considera-ções que viabilizem sua aplicação, incorre em erros que crescem com o aumento do grau de desequilíbrio dos sistemas. Para o estudo de faltas em sistemas de distribui-ção de energia elétrica, que são inerentemente desequilibrados, a aplicação do mé-todo de componentes de fase permite a obtenção de resultados mais precisos, pois considera modelos que representam o desequilíbrio do sistema. Este trabalho apre-senta um estudo analítico e numérico que analisa a influência dos desequilíbrios e da resistência de falta no cálculo das correntes de curtos-circuitos em sistemas de distri-buição empregando o método de componentes de fase, que constitui atualmente o estado da arte para o estudo de faltas nestes sistemas. A partir de um sistema de dis-tribuição simplificado, modelado com matrizes de impedâncias e admitâncias trifási-cas, calculadas na frequência fundamental do sistema, é apresentada uma equação matricial generalizada, que determina a corrente de falta que flui por uma impedância de falta, para uma dada condição faltosa. A equação proposta é analisada analítica e numericamente para o caso de faltas fase-terra. Simulações numéricas de estudos de caso em um sistema sem laterais ou cargas intermediárias, considerando diferentes graus de desequilíbrios e resistências de falta, apresentam resultados que quando comparados com os resultados para um sistema idealmente equilibrado mostram a influência que o efeito do desequilíbrio possui na determinação das correntes de curtos-circuitos e ratificam a contribuição do estudo proposto. / The approaches to short-circuit analysis of electric power systems have con-siderably improved over the last century. They were initially developed to study faults in electric power transmission systems, that have balanced characteristics and the symmetrical component method is used. As the use of this method to determine short-circuit currents in unbalanced systems requires simplifications and considera-tions to suit its application, it incurred a error increase as the systems unbalance de-gree grows. The phase components method allows more accurate results for faults study in electric power distribution systems which are inherently unbalanced as it takes into consideration models that represent the systems unbalance. Therefore an analytical and numerical study that analyses imbalance and fault resistance influence over short-circuits currents calculation in distribution systems is discussed in this work. The currently state-of-the-art method, phase components, is used to calculate faults in unbalanced systems. From an elementary distribution system modeled with three-phase impedances and admittances matrices, it is presented a general matrix equation that expresses the fault current that flows through a fault impedance due to certain fault conditions. The resulting equation is analytically and numerically ana-lysed for this fault type. Numerical simulations of a system with no lateral or inter-mediate loads, considering different imbalance degrees and fault resistances, gener-ate results that compared to the results of an ideally balanced system show the influ-ence of the systems unbalance on the fault.

Apesar do crescente desenvolvimento das metodologias de localização de faltas fundamentadas na impedância para sistemas de distribuição de energia elétrica nas últimas décadas, alguns aspectos ainda carecem de progressos, especialmente frente à crescente necessidade de aumento da qualidade da energia elétrica entregue aos consumidores. Um destes aspectos diz respeito à consideração da capacitância das linhas de distribuição, efeito nunca dantes considerado para este fim pelas metodologias baseadas em impedância aparente. Assim sendo, o presente trabalho apresenta novos desenvolvimentos relativos à consideração do efeito capacitivo para as metodologias de localização de faltas fundamentadas na impedância para sistemas de distribuição de energia elétrica. O principal desenvolvimento apresentado é um novo equacionamento para fins de localização de faltas, que torna necessária a apresentação de outro desenvolvimento, o de um algoritmo de localização de faltas que considere a capacitância da linha. As novas equações são apresentadas para todos os tipos de faltas e constituem-se de equações polinomiais de segunda ordem em relação ao local da falta. De forma a entender a resposta destas equações frente a diferentes casos de faltas e determinar qual a solução fisicamente correta destas equações, as mesmas são analisadas sob três pontos de vista, a saber, matemático, físico, e numérico. Inicialmente estas equações são analisadas de forma analítica considerandose faltas em um mesmo local, mas com resistências diferentes. Posteriormente a mesma análise é realizada numericamente através de simulações computacionais. Os desenvolvimentos propostos são também submetidos a testes de faltas, simuladas computacionalmente em um sistema sem laterais ou cargas intermediárias. Os resultados obtidos são comparados frente a resultados obtidos também para outras metodologias que constituem atualmente o estado da arte em localização de faltas fundamentada na impedância para sistemas de distribuição de energia elétrica. Através destes resultados é possível mostrar a grande influência que o efeito capacitivo possui nestas metodologias, mesmo em sistemas aéreos de distribuição, e elucidar as grandes melhorias obtidas através dos desenvolvimentos propostos. / Despite the increasing development of impedance-based fault location techniques for electric power distribution systems in the last decades, some aspects still require to progress, especially with the increasing necessity of power quality enhancement. One of these aspects regards to the distribution line shunt admittance consideration, effect that has never been considered before by the impedance-based fault location methods for power distribution systems. In this way, this work presents further improvements regarding the capacitive effect consideration for impedance-based fault location methods for power distribution systems. The main improvement presented is the development of new fault location equations, which yield the necessity of another improvement, a modified fault location algorithm that also considers the line shunt admittance. The new equations are presented for all fault types and are constituted by second-order polynomials in relation to the fault location. In order to understand the response from these equations regarding different fault situations and determine which solution is the physically feasible one, these equations are analyzed from three different points of view, i.e., mathematical, physical, and numerical. First, the developed equations are analytically analyzed considering faults in one location with different fault resistances. After, the same analysis is numerically carried out through computational simulations. The performance of the proposed improvements are also evaluated through computational simulations of faults in a power distribution system without laterals or intermediate loads. The obtained results are compared with results from the current state-of-the-art impedance-based fault location methodologies for power distribution systems. Through these results it is possible to show the great effect that the line shunt admittance, even in aerial distribution systems, has on the existing fault location methodologies and also the great improvements brought by the proposed developments.

Este documento apresenta uma metodologia analítica adaptativa para localização de faltas baseada na estimativa da impedância para sistemas de distribuição ativos. A metodologia proposta combina a informação fornecida por dispositivos eletrônicos inteligentes alocados na subestação principal e nos terminais de cada unidade de Recurso Energético Distribuído (do inglês Distributed Energy Resources - DER), o conhecimento da topologia da rede e os seus parâmetros para estimar a localização da falta. A característica adaptativa é dada pelo uso de modelos elétricos lineares para considerar o efeito das DER conectadas à rede, quando a informação fornecida pelos Dispositivos Eletrônicos Inteligentes (do inglês Intelligent Electronic Devices - IED) não é disponível. Adicionalmente, uma estratégia baseada na técnica Ladder é desenvolvida para estimar a contribuição de corrente desde as DER até o ponto de falta. Esta estratégia permite considerar vários geradores conectados e seus diferentes modos de operação. A metodologia proposta foi validada com o sistema IEEE 34 barras. Este sistema foi modelado no Alternative Transients Program (ATP) e modificado pela inserção de várias unidades DER. A metodologia proposta foi validada em vários cenários. Estes cenários avaliam o efeito da distância até a falta, resistência da falta, incerteza na carga, nível de penetração de DER, número de geradores conectados e erros nas medidas ou na estimação dos parâmetros das DER quando seus modelos forem utilizados. Para estas considerações, o desempenho da formulação proposta é satisfatório, apresentando erros menores do que 3%. / This document presents an adaptive analytical impedance-based fault location methodology for active distribution systems. The proposal combines information provided by Intelligent Electronic Devices (IEDs) located in the substation, each Distributed Energy Resources units terminal, the knowledge of the network topology as well as its parameters to estimate the fault location. Its adaptive feature is given by the use of linear analytical equivalent models to consider of DER effect in case the information provided by a local IED is not available. Additionally, a ladder-based technique is proposed to estimate the current contribution from of DER to the fault point. This process allows considering several DER connected and their different operation modes. The proposed methodology is validated on the IEEE 34-node test feeder. This system is modeled on ATP/EMTP and modified with the insertion of several DER units. The methodology is validated by considering several scenarios. These scenarios evaluate the effect of fault distance, fault resistance, load variation, DER penetration level, numbers of DERs connected and errors in the DER parameters. For these considerations, the proposed methodology performance is satisfactory, presenting fault location errors below 3%.

A maior presença de correntes harmônicas no sistema de distribuição, principalmente devido à geração distribuída, tem chamado atenção sobre suas possíveis consequências. O trabalho apresenta um método para a avaliação de harmônicas em um sistema elétrico através de um estimador de estados. A proposta é um método de supervisão da rede de distribuição utilizando o menor número de medidores possível. Isso foi feito identificando topologias de rede que viabilizam o uso de pseudomedidas no lugar de medidores. O método é aplicado a um estudo de caso baseado no modelo IEEE 13 barras e os resultados do estimador de estados foram comparados a uma simulação. Também é feita uma análise de sensibilidade do código, observando os resultados quando se adicionam erros sobre as medidas e sobre os parâmetros das linhas do sistema. / The growth of harmonic currents in distribution system, mainly due the distributed generation, is calling attention of the specialists to its possible consequences. This work presents a method to assessment of harmonics in an electric power system through a state estimator. The proposal is a method to monitor the distribution network using as few measurement devices as possible. It was performed identifying network topologies where a pseudomeasurement can replace a measurement device. The method was applied to a study case based on the IEEE 13 buses model and its results were compared to a simulation. A sensitivity analysis of the code also was performed, errors were added to measurements and lines parameters to assess the errors in the state estimator results.