Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-17T17:28:24Z No. of bitstreams: 1 RENATA GUEDES DE ALMEIDA RIBEIRO – DISSERTAÇÃO (PPGEE) 2017.pdf: 1632479 bytes, checksum: 9b29fe9df4e8998b598b4b1a8fefacb0 (MD5) / Made available in DSpace on 2018-04-17T17:28:24Z (GMT). No. of bitstreams: 1 RENATA GUEDES DE ALMEIDA RIBEIRO – DISSERTAÇÃO (PPGEE) 2017.pdf: 1632479 bytes, checksum: 9b29fe9df4e8998b598b4b1a8fefacb0 (MD5) Previous issue date: 2017-02 / CNPq / Um algoritmo de enxame de partículas foi aplicado para determinar os locais ótimos de instalação de unidades geradoras fotovoltaicas, visando redução das perdas de potência no sistema de distribuição, as quais foram calculadas pelo método da soma das correntes. O estudo considerou o índice de radiação solar e a temperatura local, o que diferencia este trabalho de outros encontrados na literatura especializada no tema. O algoritmo foi validado tomando como referência a técnica de busca exaustiva e o seu desempenho avaliado em um sistema-teste de 36-barras, no qual três fontes fotovoltaicas foram inseridas. Análise minuciosa dos resultados mostrou que o algoritmo proposto conseguiu estimar os ótimos locais para instalação das fontes fotovoltaicas. / A particle swarm algorithm (PSO) is used to determine the optimal placement for the installation of photovoltaic generators, aiming to reduce the power loss in distribution systems, which are calculated by the sum of currents method (MSI). The solar radiation index and the local temperature are considered, what distinguish this work from others found on specialized literature about the theme. The algorithm was validated using the exhaustive search technique as a reference and its performance was evaluated in a 36-bus test system, in which three photovoltaic sources were included. The rigorous analysis of the results showed that the proposed algorithm achieved its purpose to estimate de optimal placement for the installation of photovoltaic sources.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2015. / From the electric power generation perspective, the last three decades have been characterized by sustained growth in the amount of Distributed Power Generation (DPG) systems integrated into the electric grid. This trend is anticipated to continue, especially in light of the widespread acceptance of the many benefits envisaged in the increase of renewable-based power generation. The potential for grid-integrated DPG systems to significantly contribute to electric power supply reliability has consistently attracted extensive research in recent times, although concerns continue to be raised over their adverse impact on the normal grid operation at high penetration levels. These concerns largely stem from the limited controllability of most DPG systems, which tend to exhibit large output impedance variation, and non-deterministic power output characteristics. There has therefore also been a growing need to develop effective control strategies that can enhance the overall impact of the DPG systems on the grid operation, thus improving their synergistic properties, and probably also enabling an even higher penetration level into the utility grid. In line with this identified need, this thesis discusses the modeling and controller design for an inverter-based DPG system with the capability to effectively operate both in grid-connected and autonomous (i.e. independent of the utility grid) operational modes. The dual-mode operation of the DPG is made possible by incorporating into the inverter interface control scheme the means to ensure seamless transition of the DPG between the grid-connected and autonomous modes of operation. The intention is to have a grid-integrated inverter-based DPG system whose operation approximates that of an online Uninterruptible Power Supply (UPS) system, in that it is able to sustain power supply to the local load in the absence of the grid supply, which would be desirable for critical loads, for which the level of power supply reliability guaranteed by the grid often falls short of the requirements. The work developed in this thesis considers three of the aspects associated with grid-integrated DPG systems that are equipped with autonomous-mode operation capability.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology. / Distributed Generation systems based on renewable energy sources, such as wind or solar are mostly intermittent sources, due to their dependency on the weather, whereas those based on other primary energy sources are non-intermittent. All of them are specially designed to be integrated into distribution systems, in order to improve the power demand of consumers. In the last few decades of the twentieth century, several different factors have played a key role in increasing interest in systems. Distributed Generation (DG) is gaining more and more attention worldwide as an alternative to large-scale central generating stations. The aim of this research project is to investigate the contribution of distributed generation in fault current level in a power distribution system. The simulation results indicate that DG can have a positive or negative impact, on the fault current level in distribution network systems. The DG location and size affect the fault level. The second aim of this research was to suggest a model-based method for design, and implementation of a protection scheme for power distribution systems, by establish algorithms in a hardware environment. The overcurrent relay was chosen for the model development because it is considered a simple and popular protection scheme, and it is a common scheme in relaying applications. The proposed relay model was tested for fault conditions applied on a simple power system in different scenarios. The overcurrent relay model was implemented in MATLAB/Simulink, by using MATLAB programming languages and the SimPowerSystem (SPS) Tool. MATLAB/SIMULINK software is applicable to the modelling of generation, transmission, distribution and industrial grids, and the analysis of the interactions of these grids. This software provides a library of standard electrical components or models such as transformers, machines, and transmission lines. Therefore, the modelling and simulations are executed using MATLAB/Simulink version 2014b

Thesis (DTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017. / Fuel cells are among power generation technologies that have been proven to reduce greenhouse gas emissions. They have the potential of being one of the most widely used technologies of the 21st century, replacing conventional technologies such as gas turbines in stationary power supplies, internal combustion engines in transport applications and the lithium-ion battery in portable power applications. This research project concentrates on the performance analysis of a micro-cogeneration system based on a high temperatureproton exchange membrane (HT-PEM) fuel cell through modelling and parametric analysis. A model of a 1kWe micro-cogeneration system that consists of a HT-PEM fuel cell, a methane steam reformer (MSR) reactor, a water-gas-shift (WGS) reactor, heat exchangers and an inverter was developed. The model is coded/implemented in gPROMS Model Builder, an equation oriented modelling platform. The models predictions for the HTPEM fuel cell, MSR and WGS, and the whole system were validated against experimental and numerical results from literature. The validation showed that the HT-PEM fuel cell model was able to predict the performance of a 1kWe fuel cell stack with an error of less than 6.4%. The system model is rstly used in a thermodynamic analysis of the fuel processor for a methane steam reforming process and investigated in terms of carbon monoxide produced. The combustor fuel and equivalence ratios were shown to be critical decision variables to be considered in order to keep the carbon monoxide from the fuel processor at acceptable levels for the fuel cell stack.

A Geração Distribuída no Brasil tem crescido ao longo dos anos, especialmente na fonte fotovoltaica e na categoria que a ANEEL denomina microgeração distribuída, que são centrais geradoras de energia elétrica com potência instalada menor ou igual a 75 kW e conectada na rede de distribuição por meio de instalações de unidades consumidoras. Apesar dos problemas tradicionais que podem ocorrer com a inserção em larga escala, como maiores perdas e desvios de tensão, as placas fotovoltaicas, conectadas à rede de distribuição por meio de um inversor, trazem a possibilidade de controlar a tensão no ponto de conexão, manipulando-se o fator de potência de saída do inversor, controlando a potência reativa. Neste contexto, considerando o uso dos inversores inteligentes com possibilidade de envio de sinal remotamente ao operador e a possibilidade de criação de Centros de Despacho de Geração Distribuída (CDGD), este trabalho tem por objetivo propor uma metodologia de regulação de tensão centralizada utilizando unidades de microgeração fotovoltaicas, em redes de distribuição com larga inserção. A metodologia proposta utiliza o conceito de despacho de potência reativa e fluxo de potência reativa ótimo, por meio de uma abordagem centralizada da rede, utilizando-se o software OpenDSS e MatLab, equipado com Algoritmo Genético (AG) para solucionar o problema de otimização. Para avaliar o desempenho do modelo, foram feitos estudos de caso no sistema IEEE 123 barras e em uma rede real em Alegrete. Os resultados obtidos validam a abordagem proposta, demonstra a aplicabilidade e limitações em casos reais. / The distributed generation in Brazil has increased in the past years, specially in photovoltaic power generation, at the category that Brazilian Electric Regulator ANEEL classifies as "distributed micro-generation", i.e., generation units in which the active power capacity is equal or bellow 75kW and conected on distribution network by the consumers. Despite the traditional problems that might occur due to high penetration of the units, e.g., higher losses and voltage sags and swells, they are conected to the network through an inverter that can be controlled in order to provide or consume reactive power, providing voltage regulation. In that context, considering the use of intelligent inverters that can be remotely operated by a centralized utility operator, this work aims to propose a centralized voltage regulation methodology using distributed micro-generation in distribution networks. The proposed methodology uses the concept of reactive power dispatch and optimal power flow, from a centralized view of the network, using the software MatLab and OpenDSS with Genetic Algorithm to solve the optimization problem. To evaluate the model, simulations were performed with the IEEE 123 bus system and with a real distribution network from the Alegrete city, in the Brazilian state of Rio Grande do Sul. The results show the proposed is valid, despite some limitations on real cases.

Neste trabalho propõe-se um modelo de otimização que visa alocar a geração distribuída e determinar a injeção de potência ótima neste ponto, considerados três níveis de carga. Com este fim, utiliza-se uma função objetivo onde são mensuradas as perdas de potência ativa no sistema de distribuição, assim como os desvios de tensão em cada barra, sendo estes termos da função objetivo agrupados por meio de uma constante de proporcionalidade. O modelo apresenta ainda uma série de restrições, sendo estas as variáveis de decisão quanto a alocação da GD, fluxo de potência, limite de injeção de potência no sistema, relação entre as potências aparente, ativa e reativa, fator de potência e fluxo reverso de potência na subestação. Neste contexto emprega-se programação não linear com derivadas descontínuas para resolver matematicamente o modelo do sistema elétrico de potência. Quanto aos resultados, o que se observa é a grande capacidade que a GD possui, quando adequadamente ajustada, em melhorar os valores dos principais parâmetros computados neste estudo. / In this work it is proposed an optimization model that aims to allocate distributed generation and determine the optimum power injection at this point, considering three load levels. For this purpose, it is utilized an objective function which measures active power losses in the distribution system, as well as the voltage deviations at each bus, being these terms of the objective function grouped by a constant of proportionality. The model also presents a series of constraints, which are the decision variables for the allocation of DG, power flow, power injection limit on the system, the relationship between the apparent, active and reactive power, power factor and substation reverse power flow. In this context it is employed a nonlinear with discontinuous derivatives programming to mathematically solve the power system model. As for the results, what is observed is the strong influence that DG has, when properly adjusted, in the improvement of the values of the main parameters computed in this study.

Este trabalho apresenta um modelo para alocação e dimensionamento ótimo da geração distribuída em sistemas elétricos de potência. Com o objetivo de minimizar o custo da concessionária devido as perdas ativas e desvios de tensão em regime permanente, ambos foram transformados em valores monetários utilizando a normativa existente no Brasil. O problema de otimização considera uma curva de carga de 24 níveis com o intuito de simular uma curva de carga diária em intervalos de uma hora. Foram considerados limites de tensão de cada barra e corrente máxima em cada trecho do alimentador. O fluxo de potência foi estimado através do algoritmo clássico de Newton Raphson. A alocação da geração distribuída, a qual é considerada em mais de um local do alimentador, é tratada como uma variável binária no modelo desenvolvido. O modelo de otimização não-linear inteira mista é escrita mediante um algoritmo em Matlab na linguagem GAMS e enviado para o servidor de otimização NEOS e solucionado pelo solver KNITRO. O resultado é a obtenção do valor dos custos evitados para a concessionária facilitando o diagnóstico para a tomada de decisões. Por fim para verificação do método, realiza-se um estudo de caso em um sistema de distribuição de 33 barras da IEEE, sendo os resultados analisados e discutidos. / This work presents a model for optimal distributed generation sizing and allocation in power systems. The main objectives are to reduce costs for the power distribution company by power losses and compensation for voltage levels violation, both are converted in monetary values based on the Brazilian normative. The optimization problem considers a load curve with 24 levels to simulate one day in intervals of one hour. Also the model considers voltage limits for each bus and maximum currents for every line in the feeder. The power flow was formulated by the classical Newton Raphson theory. The distribution generation allocation is modeled as binary variables and can be allocated in more than one bus in the feeder. The mixed integer nonlinear model is written by a Matlab algorithm in GAMS language and solved by KNITRO through NEOS solver for optimization. The model was tested using the IEEE 33 buses, and the results were evaluated and discussed. The model lets power distribution companies reduce operational cost and penalties with optimal placement and sizing of distributed generation.

abstract: The combined heat and power (CHP)-based distributed generation (DG) or dis-tributed energy resources (DERs) are mature options available in the present energy mar-ket, considered to be an effective solution to promote energy efficiency. In the urban en-vironment, the electricity, water and natural gas distribution networks are becoming in-creasingly interconnected with the growing penetration of the CHP-based DG. Subse-quently, this emerging interdependence leads to new topics meriting serious consideration: how much of the CHP-based DG can be accommodated and where to locate these DERs, and given preexisting constraints, how to quantify the mutual impacts on operation performances between these urban energy distribution networks and the CHP-based DG. The early research work was conducted to investigate the feasibility and design methods for one residential microgrid system based on existing electricity, water and gas infrastructures of a residential community, mainly focusing on the economic planning. However, this proposed design method cannot determine the optimal DG sizing and sit-ing for a larger test bed with the given information of energy infrastructures. In this con-text, a more systematic as well as generalized approach should be developed to solve these problems. In the later study, the model architecture that integrates urban electricity, water and gas distribution networks, and the CHP-based DG system was developed. The pro-posed approach addressed the challenge of identifying the optimal sizing and siting of the CHP-based DG on these urban energy networks and the mutual impacts on operation per-formances were also quantified. For this study, the overall objective is to maximize the electrical output and recovered thermal output of the CHP-based DG units. The electrici-ty, gas, and water system models were developed individually and coupled by the devel-oped CHP-based DG system model. The resultant integrated system model is used to constrain the DG's electrical output and recovered thermal output, which are affected by multiple factors and thus analyzed in different case studies. The results indicate that the designed typical gas system is capable of supplying sufficient natural gas for the DG normal operation, while the present water system cannot support the complete recovery of the exhaust heat from the DG units. / Dissertation/Thesis / Ph.D. Electrical Engineering 2013

abstract: The past few decades have seen a consistent growth of distributed PV sources. Distributed PV, like other DG sources, can be located at or near load centers and provide benefits which traditional generation may lack. However, distribution systems were not designed to accommodate such power generation sources as these sources might lead to operational as well as power quality issues. A high penetration of distributed PV resources may lead to bi-directional power flow resulting in voltage swells, increased losses and overloading of conductors. Voltage unbalance is a concern in distribution systems and the effect of single-phase residential PV systems on voltage unbalance needs to be explored. Furthermore, the islanding of DGs presents a technical hurdle towards the seamless integration of DG sources with the electricity grid. The work done in this thesis explores two important aspects of grid inte-gration of distributed PV generation, namely, the impact on power quality and anti-islanding. A test distribution system, representing a realistic distribution feeder in Arizona is modeled to study both the aforementioned aspects. The im-pact of distributed PV on voltage profile, voltage unbalance and distribution sys-tem primary losses are studied using CYMDIST. Furthermore, a PSCAD model of the inverter with anti-island controls is developed and the efficacy of the anti-islanding techniques is studied. Based on the simulations, generalized conclusions are drawn and the problems/benefits are elucidated. / Dissertation/Thesis / M.S. Electrical Engineering 2013

O objetivo deste trabalho foi determinar o potencial de geração fotovoltaica com sistemas de microgeração sobre os edifícios dentro do campus São Paulo da USP. As diferentes topologias de sistemas fotovoltaicos conectados à rede elétrica foram descritas, apresentando as vantagens e desvantagens de cada uma delas. Em 2012, com a edição da Resolução Normativa n°482 pela Agência Nacional de Energia Elétrica (ANEEL), tornam-se possíveis no Brasil a instalação de sistemas de geração de energia a partir de fontes renováveis, de forma distribuída, onde o consumidor conectado à rede de distribuição injeta energia na rede elétrica e com isso gera créditos que são usados nos meses subsequentes. A Resolução Normativa n° 687 da ANEEL e o Convênio 16 do CONFAZ, ambos de 2015, estabeleceram novas regras que tornaram a geração distribuída mais atrativa economicamente, o que resultou no crescimento do número de instalações de forma acelerada a partir desse ano. A usina fotovoltaica do Instituto de Energia e Ambiente é formada por quatro instalações distintas e tem uma potência instalada de 540 kWp. Os dados de produção e de desempenho do primeiro ano de operação das instalações que se encontram sobre a Biblioteca Brasiliana Guita e José Mindlin e do Instituto de Estudos Brasileiros foram utilizados para que parâmetros mais adequados fossem inseridos no simulador de sistemas fotovoltaicos SISIFO. Com esses parâmetros, juntamente com dados solarimétricos do projeto SWERA e meteorológicos do INMET utilizou-se o software SISIFO para simular a capacidade de produção de energia elétrica a partir de sistemas fotovoltaicos de microgeração sobre os edifícios identificados no campus. A capacidade anual de produção de energia elétrica calculada para esses sistemas é de 2.600 MWh o que corresponde a 3,1% do consumo total de eletricidade do campus entre abril de 2015 e maio de 2016. / The goal of this work was to determine the potential of photovoltaic generation with microgeneration systems on the buildings within the São Paulo campus of USP. The different topologies of on grid photovoltaic systems were described, presenting the advantages and disadvantages of each one of them. In 2012, with the issuance of Normative Resolution No. 482 by the National Electric Energy Agency (ANEEL), it became possible in Brazil to install power generation systems from renewable sources in a distributed way, where consumers connected to the distribution network injects power into the grid and thereby generates credits that are used in the subsequent months. The Normative Resolution N ° 687 of ANEEL and CONFAZ Agreement 16, both of 2015, established new rules that made distributed generation more economically attractive, which resulted in an accelerated growth of the number of installations as of this year. The photovoltaic power plant of the Institute of Energy and Environment is formed by four distinct installations and has an installed power of 540 kWp. The production and performance data of the first year of operation of the facilities located on the Brasiliana Guita and José Mindlin Library and the Brazilian Institute of Studies were used to set the most appropriate parameters to be inserted in the SISIFO photovoltaic system simulator. With these parameters, together with solarimetric data from the SWERA project and meteorological data from INMET, SISIFO was used to simulate the electricity production capacity from photovoltaic microgeneration systems on the identified campus buildings. The annual electricity production capacity calculated for these systems is 2,600 MWh which corresponds to 3.1% of total campus consumption of electricity between April 2015 and May 2016.