Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-01-19T10:31:58Z No. of bitstreams: 1 gustavojosesantiagorosseti.pdf: 1281297 bytes, checksum: 0d547bba728df4c23bbf1317541f6e39 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-01-25T17:44:12Z (GMT) No. of bitstreams: 1 gustavojosesantiagorosseti.pdf: 1281297 bytes, checksum: 0d547bba728df4c23bbf1317541f6e39 (MD5) / Made available in DSpace on 2016-01-25T17:44:12Z (GMT). No. of bitstreams: 1 gustavojosesantiagorosseti.pdf: 1281297 bytes, checksum: 0d547bba728df4c23bbf1317541f6e39 (MD5) Previous issue date: 2015-08-31 / Esta tese apresenta uma metodologia para maximizar o restabelecimento de cargas em sistema de distribuição de energia elétrica após à ocorrência de uma ou simultâneas contingências. Para tanto, um algoritmo heurístico construtivo é proposto, determinando passo a passo os procedimentos operativos a serem adotados. Aspectos associados com as restrições de radialidade e de tensão nas barras, minimização de manobras de chaves, consumidores prioritários e mínimo corte discreto de carga são considerados a fim de uma representação mais realista do problema. A metodologia é aplicada em sistemas tradicionais da literatura, incluindo um sistema real de médio porte. / This thesis presents a methodology for maximizing the load restoration in power distribution system after simultaneous occurrence of contingency. Therefore, a heuristic constructive algorithm is proposed to determine step by step the operation procedures to be adopted. Aspects associated with the radiality and bus voltage constraints, minimization of maneuvering switches, priority consumers and minimum discrete load shedding are considered to provide a more realistic representation of the problem. The proposed approach is applied in traditional systems from literature including a real medium size test system.

This diploma thesis describes study of interconnection of Letohrad and Lanškroun water distribution systems. The thesis contains an overview of legislative regulations and technical standards related to the construction, design and directional solution of water supply systems. Following that, there is the description of the current state of the affected water mains. Next part is the design of interconnection including hydraulic analysis in using Epanet 2.0 software. The study contains several variants of the solution. The economic assessment is included.

Theoretical part of the diploma thesis purveys information on drinking water and quality requirements, changes of drinking water quality during distribution and accumulation caused by disinfection, chemical processes, corrosion of constructional materials, incrusting solids, biofilms, nitrification of ammonia nitrogen, sediments in pipelines, elution of harmful matter. Attention was given to drinking water quality indicators which are associated with changes in drinking water distribution systems. In experimental part are studied changes of drinking water quality during distribution on the basis of selected drinking water quality indicators. There is specifically chemical oxygen demand, concentration of iron, manganese, ammonia ions, nitrites, nitrates, chloroform and chlorine. For periodical monitoring were selected suitable locality within the framework of Brno distribution system; for illustration were taken water samples from distribution systems of drinking water treatment plants Švařec, Vír, Štítary and Mostiště. For selected methods of analytical determination of above mentioned drinking water quality indicators are presented their characteristics. Obtained information on drinking water quality is mentioned in tabular and graphical form.

A water distribution system (WDS) is based in a network of interconnected hydraulic components to transport the water directly to the customers. Water must be treated in a Water Treatment Plant (WTP) to provide safe drinking water to consumers, free from pathogenic and other undesirable organisms. The disinfection is an important aspect in achieving safe drinking water and preventing the spread of waterborne diseases. Chlorine is the most commonly used disinfectant in conventional water treatment processes because of its low cost, its capacity to deactivate bacteria, and because it ensures residual concentrations in WDS to prevent microbiological contamination. Chlorine residual concentration is affected by a phenomenon known as chlorine decay, which means that chlorine reacts with other components along the system and its concentration decrease. Chlorine is measured at the output of the WTP and also in several considered points within the WDS to control the water quality in the system. Simulation and modeling methods help to predict in an effective way the chlorine concentration in the WDS. The purpose of the thesis is to assess chlorine concentration in some strategic points within the WDS by using the historical measured data of some water quality parameters that influence chlorine decay. Recent investigations of the water quality have shown the need of the use of non-linear modeling for chlorine decay prediction. Chlorine decay in a pipeline is a complex phenomenon so it requires techniques that can provide reliable and efficient representation of the complexity of this behavior. Statistical models based on Artificial Neural Networks (ANN) have been found appropriated for the investigation and solution of problems related with non-linearity in the chlorine decay prediction offering advantages over more conventional modeling techniques. In this sense, this thesis uses a specific neural network application to solve the problem of forecasting the residual chlorine

[pt] Em sistemas de distribuição de energia elétrica, um dos maiores desafios para as distribuidoras é a estimação das perdas técnicas. De acordo com a bibliografia, as perdas elétricas nas redes de distribuição em diferentes países podem variar aproximadamente de 3 porcento e 25 porcento da energia fornecida à rede, o que pode significar grandes impactos nos custos do sistema. Especificamente no Brasil, a adequada avaliação das perdas elétricas fornece informação importante para que o regulador estabeleça as tarifas de distribuição de energia elétrica. Na literatura há diversos métodos para a estimação das perdas técnicas de energia, mas devido à dificuldade na modelagem dos equipamentos do sistema, assim como a falta de informação da energia consumida pelas cargas, as estimações podem acarretar em grandes erros. Para tratar este problema, esta dissertação propõe um novo método baseado em um modelo de carga polinomial modificado para estimar as perdas elétricas, considerando medições de tensão e potência na subestação e, quando disponíveis, medições de tensão e potência demandadas pelas cargas. A contribuição principal do método proposto é o uso da informação da topologia da rede e a correlação entre a potência consumida pelas cargas e as grandezas medidas na subestação. Para detalhar e analisar o desempenho do método proposto são utilizados três sistemas elétricos. Os resultados das estimações são comparados com os resultados obtidos por outros métodos de referência encontradas na literatura e em aplicações práticas. / [en] In electrical distribution systems, one of the greatest challenges for utilities is the estimation of technical losses. According to the literature, energy losses throughout the world s electric distribution networks may vary from country to country approximately between 3 percent and 25 percent of the electricity provided, which may cause great impacts on the electrical system costs. Specifically in Brazil, the appropriate evaluation of the energy losses provides valuable information for the regulator to establish the energy distribution tariffs. In literature, there are different ways for estimating energy losses, but due to the difficulty for modeling precisely the equipment of the system, as well as the lack of information regarding the energy consumed of each load, the energy losses estimation may lead to huge errors. To deal with this problem, it is proposed a new method based on a modified load model, taking into account the measurements of voltages and power at the substation and, when available, the measurements of voltages and power demanded by loads with meters installed. The main contribution of the proposed method is the use of the network information and the correlation between the power consumed by the loads and the voltage and power supplied by the substation. In order to detail and analyze the performance of the proposed method, three electric systems are used. The results of the estimations given by the proposed method are compared to those obtained with other methods found in literature and in practical applications.

[pt] Os recursos disponíveis neste trabalho são a operação do On Load Tap Changer (OLTC) da subestação, possibilidade de cortes de carga e, finalmente, o dimensionamento e despacho de baterias no sistema. Para uma análise mais realista, é abordada, ainda, uma formulação robusta da incerteza da carga e uma representação dos perfis de consumo através de cenários típicos, estabelecidos por agrupamento de similaridade, utilizando algoritmo de mineração de dados K-Means. O sistema teste modificado IEEE 123 barras é empregado na avaliação da metodologia descrita, e indica a viabilidade operacional e econômica da inserção de dispositivos armazenadores de energia no contexto de proposta do trabalho. / [en] The development of studies related to the power applications and economic feasibility of energy storage resources in electricity distribution networks has become promising considering the reduction in the cost of energy storage. Such technology can minimize the intermittence of renewable sources, provide the displacement of peak loads, extend the expansion of the electricity grid infrastructure, among other benefits. In this sense, this dissertation intends to explore and evaluate an integer-mixed linear optimization model, which is originally non-linear, for the planning and operation of energy storage systems inserted in a distribution system that may present unbalanced loads. The model seeks to minimize operation and investment costs, meeting systemic constraints, coordinating the different resources of a distribution system. The resources available in this work are the operation of the On Load Tap Changer (OLTC) of the substation, the possibility of load cuts and, finally, the sizing and dispatch of batteries in the system. For a more realistic analysis, a robust formulation of the load uncertainty and a representation of consumption profiles through typical scenarios, established by similarity clustering, using K-Means data mining algorithm are also addressed. The modified test system IEEE 123 bus is used in the evaluation of the described methodology and indicates the operational and economic feasibility of inserting energy storage devices in the context of the proposed work.

[pt] O cálculo do fluxo de potência em uma rede elétrica consiste em determinar o estado da rede, os fluxos e perdas elétricas nas linhas e as perdas internas totais no sistema. Nesse tipo de problema, a modelagem do sistema é estática e a rede é representada por um conjunto de equações e inequações algébricas. Diferentes métodos de solução foram propostos na literatura para realizar cálculos de fluxo de potência. No entanto, para redes de distribuição, esses métodos devem ser capazes de modelar, com detalhes suficientes, algumas características únicas desses sistemas, como sua estrutura quase radial, a natureza desequilibrada das cargas e a inserção de geradores distribuídos. Além disso, a modelagem do padrão de consumo nos sistemas de distribuição é mais complexa e os parâmetros das linhas são mais difíceis de serem obtidos, quando comparados com o sistema de transmissão. Portanto, a aplicação de métodos tradicionais para cálculos de fluxo de potência em redes de distribuição pode levar a soluções divergentes. Nesse contexto, o presente trabalho propõe uma nova abordagem para cálculos de fluxo de potência em sistemas de distribuição, baseada em Machine Learning. Os modelos propostos utilizam Redes Neurais Artificiais (RNAs) para prever as perdas ativas internas de uma rede de distribuição e os fluxos de potência nas fronteiras com o sistema de transmissão. Simulações numéricas demonstram o desempenho eficiente da abordagem proposta, além de suas vantagens computacionais em relação aos softwares normalmente utilizados nesse tipo de estudo pois, uma vez treinadas, as RNAs podem aproximar, de modo extremamente rápido, cálculos de fluxo de potência, já que apenas operações matriciais são realizadas. Além disso, o trabalho apresenta uma aplicação da metodologia proposta: as previsões, obtidas pela RNA, para os fluxos nas fronteiras com a rede de transmissão foram utilizadas para gerar contratos ótimos de demanda para um sistema de distribuição real no Brasil. / [en] The power flow calculation on an electric network consists of determining the network s state, power flows and electrical losses on the lines, and total losses on the feeder. In this type of problem, the system s modeling is static, and the network is represented by a set of algebraic equations and inequations. Different solution methods were proposed in the literature to perform power flow calculations. However, for distribution networks, these methods must be able to model, with sufficient details, some unique features of these systems, such as their near radial structure, the unbalanced nature of the loads, and distributed generators insertion. Besides that, modeling the consumption pattern in distribution systems is more complex, and the line parameters are more difficult to be obtained when compared to the transmission system. Hence, applying traditional methods for power flow calculations in distribution networks may lead to divergent solutions. Within this context, this work proposes a new approach for power flow calculations in distribution systems based on Machine Learning. The proposed models use Artificial Neural Networks (ANNs) to predict the active internal losses of a distribution network and the power flows at the borders with the transmission system. Numerical simulations demonstrate the effective performance of the proposed approach, as well as its computational advantages over benchmark software programs since, once trained, ANNs can approximate power flow calculations extremely fast, as only matrix operations are needed. Moreover, the work presents an application of the ANN methodology proposed: predictions of the flows at the borders with the transmission network were used to generate optimal demand contracts for a real distribution system in Brazil.

The research reported in this dissertation focuses on the development of optimization tools for the design of subsystems in a modern aircraft power distribution system. The baseline power distribution system is built around a 270V DC bus. One of the distinguishing features of this power distribution system is the presence of regenerative power from the electrically driven flight control actuators and structurally integrated smart actuators back to the DC bus. The key electrical components of the power distribution system are bidirectional switching power converters, which convert, control and condition electrical power between the sources and the loads. The dissertation is divided into three parts. Part I deals with the formulation of an optimization problem for a sample system consisting of a regulated DC-DC buck converter preceded by an input filter. The individual subsystems are optimized first followed by the integrated optimization of the sample system. It is shown that the integrated optimization provides better results than that obtained by integrating the individually optimized systems. Part II presents a detailed study of piezoelectric actuators. This study includes modeling, optimization of the drive amplifier and the development of a current control law for piezoelectric actuators coupled to a simple mechanical structure. Linear and nonlinear methods to study subsystem interaction and stability are studied in Part III. A multivariable impedance ratio criterion applicable to three phase systems is proposed. Bifurcation methods are used to obtain global stability characteristics of interconnected systems. The application of a nonlinear design methodology, widely used in power systems, to incrementally improve the robustness of a system to Hopf bifurcation instability is discussed. / Ph. D.

Integration of a cyber system and communication systems with the traditional power grid has enabled better monitoring and control of the smart grid making it more reliable and resilient. This empowers the system operators to make informed decisions as a result of better system visibility. The grid has moved from a completely air-gapped structure to a well-connected network. However, this remote-control capability to control distributed physical components in a distribution system can be exploited by adversaries with malicious intent to disrupt the power supply to the customers. Therefore, while taking advantage of the cyber-physical posture in the smart grid for improved controllability, there is a critical need for cybersecurity research to protect the critical power infrastructure from cyberattacks. While the literature regarding cybersecurity in distribution systems has focused on detecting and mitigating the cyberattack impact on the physical system, there has been limited effort towards a preventive approach for detecting cyberattacks. With this in mind, this dissertation focuses on developing intelligent solutions to detect cyberattacks in the cyber layer of the distribution grid and prevent the attack from impacting the physical grid. There has been a particular emphasis on the impact of coordinated attacks and the design of proactive defense to detect the attacker's intent to predict the attack trajectory. The vulnerability assessment of the cyber-physical system in this work identifies the key areas in the system that are prone to cyberattacks and failure to detect attacks timely can lead to cascading outages. A comprehensive cyber-physical system is developed to deploy different intrusion detection solutions and quantify the effect of proactive detection in the cyber layer. The attack detection approach is driven by artificial intelligence to learn attack patterns for effective attack path prediction in both a fully observable and partially observable distribution system. The role of effective communication technology in attack detection is also realized through detailed modeling of 5G and latency requirements are validated. / Doctor of Philosophy / The traditional power grid was designed to supply electricity from the utility side to the customers. This grid model has shifted from a one-directional supply of power to a bi-directional one where customers with generation capacity can provide power to the grid. This is possible through bi-directional data flow which ensures the complete power system observability and allows the utility to monitor and control distributed power components remotely. This connectivity depends on the cyber system and efficient communication for ensuring stable and reliable system operations. However, this also makes the grid vulnerable to cyberattacks as the traditional air-gapped grid has evolved into a highly connected network, thus increasing the attack surface for attackers. They might pose the capability to intrude on the network by exploiting network vulnerability, move laterally through different aspects of the network, and cause operational disruption. The type of disruption can be minor voltage fluctuations or even widespread power outages depending on the ultimate malicious attack goal of such adversaries. Therefore, cybersecurity measures for protecting critical power infrastructure are extremely important to ensure smooth system operations. There has been recent research effort for detecting such attacks, isolating the attacked parts in the grid, and mitigating the impact of the attack, however, instead of a passive response there is a need for a preventive or proactive detection mechanism. This can ensure capturing the attack at the cyber layer before intruders can impact the physical grid. This is the primary motivation to design an intrusion detection system that can detect different coordinated attacks (where different attacks are related and directed towards a specific goal) and can predict the attack path. This dissertation focuses on first identifying the vulnerabilities in the distribution system and a comprehensive cyber-physical system is developed. Different detection algorithms are developed to detect cyberattacks in the distribution grid and have the intelligence to learn the attack patterns to successfully predict the attack path. Additionally, the effectiveness of advanced communication such as 5G is also tested for different system operations in the distribution system.

[ES] El objetivo general de la presente Tesis es investigar metodologías que permitan obtener en tiempo real los parámetros de operación de redes hidráulicas a presión que minimicen el consumo y/o el coste energético, garantizando el cumplimiento de las condiciones de funcionamiento necesarias para una adecuada calidad del servicio. Al tratarse del ámbito de la operación diaria de la red, una de las condiciones indispensables que deben reunir los métodos de optimización es una respuesta lo suficientemente rápida como para que no solo se pueda disponer de las soluciones más convenientes en el momento de ejecutar las consignas de operación, sino que además se habilite un procedimiento flexible que permita dar respuesta a posibles cambios en las predicciones o eventos que puedan producirse. Se ha abordado de manera aislada la optimización energética de los subsistemas de transporte de agua y la de los subsistemas de distribución debido a las distintas características que se pueden observar en ellos. En la parte relativa a los subsistemas de distribución, particularizada al caso de un sistema de riego con bombeo directo a red, se han explorado los métodos metaheurísticos de optimización, realizando varias aportaciones originales orientadas a la mejora en la eficiencia computacional de los mismos, debido a la necesidad de obtener una respuesta rápida compatible con la toma de decisiones en tiempo real. En cuanto a los subsistemas de transporte, se ha explorado la aplicabilidad del método determinista de optimización por programación lineal, a la vista de las importantes ventajas que presenta respecto al resto de métodos generales de optimización. Asimismo, en el contexto de los subsistemas de transporte, se ha trabajado en la definición de una heurística basada en el cálculo del coste energético y/o económico del agua entregada en los puntos de consumo y almacenada en los depósitos intermedios, que ha permitido formular un algoritmo voraz para la optimización energética en cada instante de tiempo. Este método ha conseguido igualar el desempeño alcanzado mediante la programación lineal y se espera que ofrezca unas mejores capacidades en sistemas con un comportamiento marcadamente no lineal, así como también una mejor adaptación a problemas de optimización con la participación de energías renovables. / [CA] L'objectiu general de la present Tesi és la investigació de metodologies que permeten obtindre en temps real els paràmetres d'operació de xarxes hidràuliques a pressió que minimitzen el consum i/o el cost energètic, garantint el compliment de les condicions de funcionament necessàries per a una adequada qualitat del servei. En tractar-se de l'àmbit de l'operació diària de la xarxa, una de les condicions indispensables que han de reunir els mètodes d'optimització és una resposta prou ràpida com perquè no sols es puga disposar de les solucions més convenients en el moment d'executar les consignes d'operació, sinó que a més s'habilite un procediment flexible que permeta donar resposta a possibles canvis en les prediccions o esdeveniments que puguen produir-se. S'ha abordat de manera aïllada l'optimització energètica dels subsistemes de transport d'aigua i la dels subsistemes de distribució (reg per injecció directa) a causa de les diferents característiques que es poden observar en ells. En el treball amb els subsistemes de distribució s'han explorat les possibilitats que ofereixen els mètodes meta-heurístics d'optimització, realitzant diverses aportacions originals orientades a la millora en l'eficiència computacional dels mateixos a causa de la necessitat d'obtindre una resposta més ràpida que siga compatible amb la presa de decisions en temps real. Quant als subsistemes de transport, s'ha explorat l'aplicabilitat del mètode determinista d'optimització per programació lineal a la vista dels importants avantatges que presenta respecte a la resta de mètodes generals d'optimització. Així mateix, en el context dels subsistemes de transport, s'ha treballat en la definició d'una bona heurística basada en el càlcul del cost energètic i/o econòmic de l'aigua entregada en els punts de consum i en els dipòsits intermedis, que ha permés formular un mètode voraç per a l'optimització energètica en cada instant de temps. Aquest mètode ha aconseguit igualar l'acompliment aconseguit mitjançant la programació lineal i s'espera que oferisca unes millors capacitats en sistemes amb un comportament més marcadament no lineal, així com també una millor adaptació a problemes d'optimització amb participació d'energies renovables. / [EN] The general objective of this Thesis is the research of methodologies to obtain in real time the operating parameters of pressurized hydraulic networks that minimize energy consumption and/or cost, ensuring compliance with the operating conditions necessary for an appropriate quality of service. Since this is the field of daily network operation, one of the indispensable conditions that optimization methods must meet is a response fast enough so that not only the most convenient solutions are available at the time of executing the operating instructions, but also a flexible procedure is provided to allow a response to possible changes in the predictions or events that may occur. The energy optimization of the water transport subsystems and that of the distribution subsystems (direct injection irrigation) have been approached separately due to the different characteristics that can be observed in them. In the work with distribution subsystems, the possibilities offered by metaheuristic optimization methods have been explored, making several original contributions aimed at improving their computational efficiency due to the need to obtain a faster response that is compatible with real-time decision making. Regarding transport subsystems, the applicability of the deterministic method of optimization by linear programming has been explored in view of the important advantages it presents with respect to the rest of the general optimization methods. Also, in the context of transport subsystems, there has been a work on the definition of a good heuristic based on the calculation of the energy and/or economic cost of the water delivered at the consumption points and intermediate reservoirs, which has allowed to formulate a greedy method for energy optimization at each time instant. This method has been able to match the performance achieved by linear programming and is expected to offer better capabilities in systems with a more marked non-linear behaviour, as well as a better adaptation to optimization problems involving renewable energies. / Alonso Campos, JC. (2021). Desarrollo e implementación de algoritmos para la optimización energética en tiempo real de redes hidráulicas a presión [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/180389