This thesis presents a novel, fast, and accurate 3 steady-state power-flow analysis (PFA) tool for the real-time operation of the active distribution systems, also known as the active distribution networks (ADN), in the grid-tied and islanded operating modes. Three-phase power-flow models of loads, transformers, and multi-phase power lines and laterals are provided. This thesis also presents novel steady-state, fundamental-frequency, power-flow models of voltage-sourced converter (VSC)-based distributed energy resource (DER) units. The proposed models address a wide array of DER units, i.e., (i) variable-speed wind-driven doubly-fed asynchronous generator-based and (ii) single/three-phase VSC-coupled DER units. In addition, a computationally-efficient technique is proposed and implemented to impose the operating constraints of the VSC and the host DER unit within the context of the developed PFA tool. Novel closed forms for updating the corresponding VSC power and voltage reference set-points are proposed to guarantee that the power-flow solution fully complies with the VSC constraints. All the proposed DER models represent (i) the salient VSC control strategies and objectives under balanced and unbalanced power-flow scenarios and (ii) all the operating limits and constraints of the VSC and its host DER unit. Also, the slack bus concept is revisited, associated with the PFA, where a 3 distributed slack bus (DSB) model is proposed for the PFA and operation of islanded ADNs. Distributing the real and reactive slack power among several DER units is essential to provide a realistic power-flow approach for ADNs in the absence of the utility bus. The proposed DSB model is integrated with the developed 3 PFA tool to form a complete ADN PFA package. The new PFA tool, including the proposed DER and DSB models, is tested using several benchmark networks of different sizes, topologies, and parameters. Many case studies, encompassing a wide spectrum of DER control specifications and operating modes, are conducted to demonstrate (i) the numerical accuracy of the proposed models of the DER units and their operating constraints, (ii) the effectiveness of the proposed DSB model for the islanded ADN PFA, and (iii) the computational efficiency of the integrated PFA software tool irrespective of the network topology and parameters.

This thesis presents a novel, fast, and accurate 3 steady-state power-flow analysis (PFA) tool for the real-time operation of the active distribution systems, also known as the active distribution networks (ADN), in the grid-tied and islanded operating modes. Three-phase power-flow models of loads, transformers, and multi-phase power lines and laterals are provided. This thesis also presents novel steady-state, fundamental-frequency, power-flow models of voltage-sourced converter (VSC)-based distributed energy resource (DER) units. The proposed models address a wide array of DER units, i.e., (i) variable-speed wind-driven doubly-fed asynchronous generator-based and (ii) single/three-phase VSC-coupled DER units. In addition, a computationally-efficient technique is proposed and implemented to impose the operating constraints of the VSC and the host DER unit within the context of the developed PFA tool. Novel closed forms for updating the corresponding VSC power and voltage reference set-points are proposed to guarantee that the power-flow solution fully complies with the VSC constraints. All the proposed DER models represent (i) the salient VSC control strategies and objectives under balanced and unbalanced power-flow scenarios and (ii) all the operating limits and constraints of the VSC and its host DER unit. Also, the slack bus concept is revisited, associated with the PFA, where a 3 distributed slack bus (DSB) model is proposed for the PFA and operation of islanded ADNs. Distributing the real and reactive slack power among several DER units is essential to provide a realistic power-flow approach for ADNs in the absence of the utility bus. The proposed DSB model is integrated with the developed 3 PFA tool to form a complete ADN PFA package. The new PFA tool, including the proposed DER and DSB models, is tested using several benchmark networks of different sizes, topologies, and parameters. Many case studies, encompassing a wide spectrum of DER control specifications and operating modes, are conducted to demonstrate (i) the numerical accuracy of the proposed models of the DER units and their operating constraints, (ii) the effectiveness of the proposed DSB model for the islanded ADN PFA, and (iii) the computational efficiency of the integrated PFA software tool irrespective of the network topology and parameters.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / This work aims to quantify the impact in the steady state operation of a distribution system when electric vehicles are connected. It is worth noting that the connection of them may cause significant changes in the voltage profile, in the degree of voltage unbalance and in the electrical losses of the system. In order to make this analysis, a three-phase power flow program was developed in MATLAB language. This program is based on the Ladder Iterative Technique and it contains models of overhead distribution lines, underground distribution lines, spot loads, distributed loads connected in wye and delta, step voltage regulators, capacitor banks, three-phase transformers and the model of an electric vehicle. This model allows simulation of a real electric vehicle of model Tesla Roadster, produced by Tesla Motors. The test system used in all simulations was the IEEE 13 bus. Moreover, the methodology consisted in simulate the system with the voltage regulator and without the voltage regulator under heavy load and light load conditions. The electric vehicle was connected to a specific systemâs bus and it were considered that it could work as a load or as a distributed generator with or without positive sequence voltage control. Constants configurations of the electric vehicles were considered for the heavy load and light load cases. The results of the simulations reveal there was voltage violation due to the connection of electric vehicles acting as loads in the test system under heavy load conditions without voltage regulator. When they operate as generators, they can maintain the voltage unbalance under the allowed 2%, turning the systemâs voltages more balanced. There were significant reductions when the electric vehicles acted as a load (71.1%) and as generator (77.5%) on the total real power losses when the system operated with voltage regulator on the substation and the electric vehicles operated with positive sequence voltage control (specified at 1,0 pu). / Este trabalho tem o objetivo de quantificar o impacto da conexÃo de veÃculos elÃtricos na operaÃÃo em regime permanente de um sistema de distribuiÃÃo. à visto que a conexÃo dos mesmos pode causar mudanÃas significativas no perfil de tensÃes, no grau de desequilÃbrio de tensÃo e nas perdas elÃtricas do sistema. Para realizar essa anÃlise, desenvolveu-se um programa de fluxo de potÃncia trifÃsico na linguagem MATLAB. O programa à baseado na tÃcnica iterativa de escada. Foram implementados nesse programa modelos de linhas de distribuiÃÃo aÃreas e subterrÃneas, modelos de cargas concentradas e distribuÃdas conectadas em delta e em estrela, modelos de reguladores de tensÃo, modelos de banco de capacitores, modelo de transformadores trifÃsicos e o modelo do veÃculo elÃtrico. Esse modelo permite simular o veÃculo elÃtrico Tesla Roadster da Tesla Motors. O sistema teste utilizado em todas as simulaÃÃes foi o sistema IEEE 13 barras. A metodologia utilizada consistiu em simular o sistema sem regulador de tensÃo e com o regulador de tensÃo, em carga pesada e em carga leve. O veÃculo elÃtrico foi conectado a uma barra do sistema e considerou-se que o mesmo podia funcionar como carga ou gerador distribuÃdo sem e com controle de tensÃo de sequÃncia positiva no ponto de conexÃo. Adotou-se disposiÃÃes constantes de veÃculos elÃtricos para os casos de carga pesada e carga leve. Os resultados das simulaÃÃes revelam que houve violaÃÃo de tensÃo devido à inserÃÃo de veÃculos elÃtricos atuando como carga no sistema teste em carga pesada sem regulador de tensÃo. Jà quando operam como gerador, os veÃculos elÃtricos diminuem o grau de desequilÃbrio em mÃdia, podendo mantÃ-lo abaixo do limite permitido de 2 %, tornando assim as tensÃes das barras trifÃsicas do sistema mais equilibradas. Houve reduÃÃes significativas quando os veÃculos elÃtricos atuaram como carga (71,1 %) e como gerador (77,5 %) na perda de potÃncia ativa total do sistema quando o sistema operou com regulador de tensÃo na subestaÃÃo e os veÃculos elÃtricos operaram com controle de tensÃo de sequÃncia positiva (especificada em 1,0 pu).

Made available in DSpace on 2014-07-29T15:08:18Z (GMT). No. of bitstreams: 1 DISSERTACAO_MESTRADO_Rodrigo M de Carvalho_2012.pdf: 3438844 bytes, checksum: 3b54078140704053b5706662ad841ff3 (MD5) Previous issue date: 2012-04-20 / As a distribution network grows, the need for voltage control and regulator devices increases, as well as the need for supplying the demands, which assists in monitoring and correction of their magnitudes. Thus, the use of voltage regulators and, more recently, distributed generation applications contribute to the improvement of the process of electric power distribution in order not only to supply the demands, but the quality of the energy supplied. This dissertation presents three three-phase step-voltage regulator models, each of Type B, and two distributed generation models, all of them implemented in a power flow application prepared according to the Backward/Forward Sweep algorithm. The three-phase voltage regulator models differ in their connection, that is, grounded-wye, closed-delta and open-delta, while models of distributed generation are identified by technology and size, being classified into PQ and PV nodes. Results are obtained from three distribution networks for different cases of use of voltage regulators and distributed generation. IEEE 13 and 34 bus systems were used for testing the evaluation algorithm and a 103 bus network, derived form one of the CELG distribution systems, were used as a real case example for the application of the implemented models of voltage regulators and distributed generation. The results were discussed and reviewed so that it is possible to identify the most efficient templates for each case or for the majority of the cases. / À medida que cresce uma rede de distribuição, aumenta a necessidade de dispositivos para a regulação e controle de tensão, assim como para suprimento das demandas, o que auxilia na monitoração e correção de suas magnitudes. Assim, a utilização de regulador de tensão e, mais recentemente, a aplicação de geração distribuída contribuem para o aperfeiçoamento do processo de distribuição da energia elétrica tendo em vista não só o atendimento da demanda, mas a qualidade da eletricidade fornecida. Esta dissertação apresenta três modelos de regulador de tensão de passo trifásico, todos do Tipo B, e dois modelos de geração distribuída, todos implementados em um aplicativo de fluxo de potência, o qual foi elaborado segundo o algoritmo Backward/Forward Sweep. Os modelos de regulador de tensão trifásicos se diferem em suas conexões, isto é, estrela aterrada, delta fechado e delta aberto, enquanto que os modelos de geração distribuída são identificados por sua tecnologia e tamanho, podendo se classificar em nós PQ e PV. São obtidos resultados a partir de três redes de distribuição para diferentes situações de utilização do regulador de tensão e da geração distribuída. Foram utilizadas os sistemas de 13 e 34 barras do IEEE para realização de testes avaliativos do algoritmo proposto e uma rede de 103 barras, derivada do sistema CELG de distribuição, como exemplo de caso real para aplicação dos modelos implementados de regulador de tensão e geração distribuída. Os resultados são comentados e analisados de forma que seja possível a identificação dos modelos mais eficientes para cada caso ou ainda para a maioria dos casos.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-25T18:26:00Z No. of bitstreams: 1 ricardovioldossantos.pdf: 2585437 bytes, checksum: 897e63c2118d5c0e74581bbdb80ccb38 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-26T12:23:14Z (GMT) No. of bitstreams: 1 ricardovioldossantos.pdf: 2585437 bytes, checksum: 897e63c2118d5c0e74581bbdb80ccb38 (MD5) / Made available in DSpace on 2017-04-26T12:23:14Z (GMT). No. of bitstreams: 1 ricardovioldossantos.pdf: 2585437 bytes, checksum: 897e63c2118d5c0e74581bbdb80ccb38 (MD5) Previous issue date: 2015-08-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Buscando corrigir aspectos relacionados à qualidade de energia, bancos de capacitores em derivação são utilizados em alimentadores primários dos sistemas de distribuição. A busca pela melhor forma de alocação constitui um problema complexo de natureza matemática combinatória, ao incluir critérios técnicos conflitantes e restrições do sistema. Este problema não tem solução trivial, tornando-se importante a formulação de metodologias para auxiliar nessa tarefa. Neste trabalho, é proposta uma metodologia para alocação de bancos de capacitores em derivação em nós do sistema elétrico, com possibilidade de alocação desequilibrada, considerando sua natureza discreta, com objetivo de minimizar desequilíbrios de tensão e custos de alocação, baseada em aplicação de algoritmo genético. Foram consideradas também restrições tais como limites de correntes nos alimentadores, limites de tensão para a conformidade com as faixas adequadas de tensão padronizadas pelos órgãos competentes e a disponibilidade de bancos. / Seeking for correcting issues related to power quality, shunt capacitor banks are used in primary feeders of distribution systems. The search for the best allocation is a complex problem of combinatorial mathematical nature, including conflicting technical criteria and constraints of the system. This problem has nontrivial solution, making important the development of methodologies to assist in this task. In this work, it is proposed a methodology for allocation of shunt capacitor banks in electric system nodes, with the possibility of unbalanced allocation, considering its discrete nature, with the purpose of minimizing voltage imbalances and allocating costs, based on genetic algorithm application. Restrictions such as limits of current feeders, voltage limits for compliance with the appropriate standard voltage ranges and the availability of capacitor banks were considered.