Made available in DSpace on 2014-06-11T19:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-06-06Bitstream added on 2014-06-13T21:01:24Z : No. of bitstreams: 1 carvalho_cg_dr_ilha.pdf: 1638470 bytes, checksum: ca46c8123050c9866b9ab13bc540b94d (MD5) / Este trabalho apresenta um modelo analítico para uma linha de transmissão trifásica com plano de simetria vertical. Devido às características físicas dessa linha, é possível representá-la por um sistema constituído por uma linha monofásica e por uma linha bifásica. Nesse sistema, as equações que descrevem o comportamento das grandezas nos terminais da linha monofásica são conhecidas, enquanto que as equações da linha bifásica foram obtidas utilizando uma matriz de transformação escrita explicitamente em função dos parâmetros da linha trifásica. Em seguida, as grandezas modais da linha trifásica foram convertidas para o domínio das fases e as equações resultantes representam um modelo analítico desenvolvido diretamente no domínio das fases dessa linha. Para verificar o desempenho do modelo, foram realizadas simulações considerando a energização e a incidência de uma descarga atmosférica em uma linha trifásica de 440 kV. Esses resultados foram comparados aos resultados obtidos com a linha representada por meio de um método clássico (representação nos modos) e as simulações mostraram que o modelo responde adequadamente na faixa de frequência correspondente aos procedimentos de manobra e chaveamento. O modelo desenvolvido leva em conta o efeito da frequência sobre os parâmetros longitudinais da linha e também o fato de que os parâmetros da linha são distribuídos ao longo de seu comprimento. Acredita-se que a análise das matrizes, que dão suporte ao modelo, e a validação do modelo no domínio do tempo possa dar origem, futuramente, a um modelo de linha de transmissão desenvolvido diretamente no domínio do tempo. Tal modelo, pelo fato de ser obtido diretamente das equações de propagação da linha, permitirá a obtenção de resultados de simulações, de transitórios eletromagnéticos que ocorrem... / This paper presents an analytical model to a three-phase transmission line with vertical symmetry plane. Because of physical characteristics of this line, it is possible to represent it by a system consisting of a single-phase and a two-phase line. In this system, the equations that describe the behavior of single-phase terminals quantities are known, while the two-phase equations were obtained using a transformation matrix written explicitly in terms of the parameters of three-phase line. Then, the modal quantities of three-phase line were converted into phase domain and the resulting equations represent an analytical model developed directly in phase domain of this line. To verify the performance of the model, were performed simulations considering the energization and impact of a lighting surge in a 440 kV three-phase line. These results were compared to results obtained with the line represented by a classical method (presentation modes) and simulations show that the model responds appropriately in the frequency range corresponding to the operation and switching procedures. The model developed takes into account the frequency effect on the longitudinal line parameters and also the fact that the line parameters are distributed along their length. It is believed that the matrix analysis, that support the model and the model validation in time domain may give rise in the future to a transmission line model developed directly in time domain. Such a model, because it is obtained directly from the propagation equations of line, will enable the more accurate results of simulations of electromagnetic transients that... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-03-25Bitstream added on 2014-06-13T19:06:32Z : No. of bitstreams: 1 santos_db_dr_ilha.pdf: 749223 bytes, checksum: a2917d0d97ef24108b6802f76937b5c1 (MD5) / O problema de planejamento da expansão de sistemas de transmissão de energia elétrica a longo prazo é um importante problema de otimização do campo do planejamento de sistema elétricos de potência. Trata-se de um problema cujo modelo matemático é um problema de programação não linear inteiro misto com a complexidade adicional de que é um problema não convexo e com característica de apresentar o fenômeno da explosão combinatória quando cresce as alternativas de expansão. O processo de resolução consiste basicamente nas escolhas de circuitos, dentro de um conjunto pré-definido, donde o candidato a ser incorporado ao sistema deverá apresentar resultados positivos no que tange a minimização do custo de investimento e operação e, além disso, deve atender a demanda de energia futura ao longo de um horizonte de planejamento com confiabilidade, assumindo como conhecido o plano de geração. Devido a complexidade do problema tem-se tentado aplicar todas as técnicas de otimização para auxiliar na tentativa de resolução. Sendo estas técnicas classificadas em três grandes grupos: técnicas de otimização clássica, técnicas heurísticas e técnicas metaheurísticas. Neste trabalho apresenta-se uma nova forma de resolução, oriunda do grupo , denominada Busca em vizinhança variável (VNS). O VNS é uma metaheurística recente que explora basicamente a ideia de mudança sistemática de estruturas de vizinhança no espaço de soluções durante o processo de busca para encontrar soluções ótimas locais e para sair desses ótimos locais. Esta técnica de solução oferece novas alternativas de solução, comparado com os diversos tipos de metaheurísticas já utilizadas na literatura, apresentando excelentes resultados com baixo esforço computacional. Os algoritmos utilizados são apresentados e detalhados a sua forma de... / The expansion planning problem of the power electrical transmission system to long term is an important problem of optimization of power electrical system fields. It refers to a problem whose mathematical model is a non-linear whole mixed program problem with additional complexity is a non-convex problem and presents the feature of the combinatorial expansion when grows the expansion alternatives. The reduction process is just choices of circuits in a pre-defined array where the candidate, which should be incorporated to the system, should have positive minimization cost of investment and operation and should support the future energy demand along of a reliable horizon of planning to a known generation plan. In the past, many optimization methods were tested to search the best solution due the problem complexity. These methods can be classified by: classical optimization methods, heuristic methods and meta-heuristic methods. However, in this work is presented a new approach of solution based on the method of Variable Neighborhood Search (VNS). The VNS is a modern meta-heuristic uses a systematic change of neighborhood structures over solution space during the search procedure of optimal local solutions and to go out from local optimum. Thus, this approach provides new alternatives of solution in comparison with other meta-heuristic methods previously found at the literature. Additionally, the new approach presents excellent results with low computational cost. In summary, the used algorithms are showed and the adaptation mode to the planning problem of the power electrical transmission system is described. This adaptation considers two traditional mathematical models: Transport and DC models. Lastly, it was performed tests with the bars/paths IEEE system, the bars/paths south Brazilian system and... (Complete abstract click electronic access below)

Thesis (Master of Engineering in Electrical Engineering))--Cape Peninsula University of Technology, 2018. / Transformer Differential and overcurrent schemes are traditionally used as main and backup protection respectively. The differential protection relay (SEL487E) has dedicated harmonic restraint function which blocks the relay during the transformer magnetizing inrush conditions. However, the backup overcurrent relay (SEL751A) applied to the transformer protection does not have a harmonic restraint element and trips the overcurrent relay during the inrush conditions. Therefore, to prevent the malfunction caused by the transformer magnetizing inrush current, a novel harmonic blocking method is developed, implemented and tested in the RSCAD simulation environment. The IEEE 14 bus transmission system is considered as a case study. The IEEE 14 bus system is modelled and simulated in the DIgSILENT and RSCAD simulation environments respectively. The developed harmonic blocking scheme is implemented in the Hardware-In-the-Loop (HIL) simulation environment using Real-Time Digital Simulator and numerical protection IEDs. The developed scheme uses the Harmonic Blocking element (87HB) of the transformer differential relay (SEL487E) to send an IEC61850 GOOSE-based harmonic blocking signal to the backup overcurrent relay (SEL751A) to inhibit it from tripping during the transformer magnetizing inrush current conditions. The hardwired and GOOSE simulation results are analysed for the transformer differential protection and the backup overcurrent protection schemes for internal, external events and transformer magnetizing inrush current conditions. The simulation results proved that the IEC61850 standard-based protection scheme is faster than the hardwired. Therefore, the speed and reliability are improved using the IEC61850 standard-based GOOSE applications to the transformer digital protective relaying system.

Made available in DSpace on 2015-07-13T12:10:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-27. Added 1 bitstream(s) on 2015-07-13T12:25:33Z : No. of bitstreams: 1 000836334.pdf: 1535440 bytes, checksum: 8662c660666cc734fb6a0b7771db7959 (MD5) / Esta dissertação apresenta a modelação, metodologia de projeto e os principais resultados de simulação para um elemento eletromagnético de transmissão indutiva de energia elétrica sem fios, aplicado em postos de abastecimento de Veículos Elétricos (VE) puros. A estrutura proposta é composta por no mínimo dois indutores, sendo um deles o emissor e o outro o receptor de energia. Realizou-se uma revisão bibliográfica das estruturas dos sistemas utilizados para a transmissão de energia eletromagnética sem fios (wireless) e, predominantemente, as mesmas utilizam-se de indutores com formatos espirais cilíndricos ou quadrados, para formar os elementos para transmissão de energia. Neste contexto, este trabalho baseou-se apenas em indutores com formato espiral cilíndrico, sendo estes analisados com base nas teorias do eletromagnetismo, partindo-se da Lei de Biot Savart e da Terceira Lei de Maxwell, com o intuito de obter-se os principais parâmetros de projeto para o elemento de transferência indutiva de potência (IPT - Inductive Power Transfer), quais sejam: Indutância Mútua (emissor/receptor), Indutância Própria (emissor) e Fator de Acoplamento (emissor/receptor). A fim de comprovar a exatidão da metodologia teórica desenvolvida, adotaram-se modelos computacionais utilizando-se o software Comsol ®, onde se construiu o modelo físico do elemento de transmissão de energia (IPT), para cada caso analisado. Os resultados obtidos decorrentes da modelação teórica proposta são inéditos e o trabalho pioneiro em determinar algebricamente um método de cálculo para o acoplamento mútuo entre indutores com geometrias espirais cilíndricas que, quando comparados com os resultados de simulações obtidos através do Comsol ®, demonstraram-se praticamente exatos. Considerando-se a aplicação num estudo de caso de transmissão de energia sem fios (WPT - Wireless Power Transfer), para um Veículo Elétrico (VE) puro em escala... / This work proposes a modeling, design methodology and shows the main simulation results to the development of a Wireless Power Transmission (WPT) element, applied to pure Electric Vehicles (EV). The proposed structure is composed of at least two inductors, composing a transmitter and an energy receiver with weak magnetic coupling among them, considering a far-field energy-transfer method. Considering a literature review for the structures of the systems used for Wireless Power Transmission (WPT), it was observed the use of cylindrical spiral or square shapes, predominantly, in order to compose the inductive elements for power transmission. In this context, this work was based only on inductors with cylindrical spiral shape, which was analyzed based on electromagnetism theories. The proposed methodology starts from the Biot Savart Law and the Third Maxwell Law, in order to obtain the key design parameters for the inductive power transfer element (IPT - Inductive Power Transfer), which are: Mutual Inductance (transmitter / receiver), Self Inductance (transmitter) and Coupling Factor (transmitter / receiver). In order to prove the accuracy of the developed theoretical methodology, was adopted a computational model using the Comsol® software, considering a physical model for the designed IPT element. The results obtained from the proposed theoretical modeling are original and this is a pioneering work in determining algebraically a calculation method for mutual coupling between cylindrical spiral inductors that, when compared with the simulation results obtained by Comsol®, demonstrated practically exact. Furthermore, considering the application in a small-scale case study to WPT, for a pure Electric Vehicle (EV), an important contribution presented in this work is the analysis of arrangements for the inductive element of power transmitter, presenting its advantages and disadvantages and the best configuration for the case study. It should ...

Made available in DSpace on 2014-12-02T11:16:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-27Bitstream added on 2014-12-02T11:20:50Z : No. of bitstreams: 1 000797343.pdf: 769171 bytes, checksum: e4b6a7c175e5957d6ca52df5c59819d1 (MD5) / Neste trabalho foi apresentado uma nova modelagem matemática para problemas de Planejamento da expansão de sistemas de transmissão ao longo prazo que permite uma mudança no conceito de expansão de sistema de transmissão. Nos problemas de planejamento da expansão de sistemas de transmissão tradicionais apenas as adições de linhas candidatas são consideradas. Neste trabalho um novo conceito de planejamento da expansão do sistema de transmissão é encontrar uma nova solução para a topologia base onde todas as linhas estão temporariamente desconectadas e a implementação dessas linhas são reconsideradas quando elas podem voltar à sua posição anterior. Portanto as linhas da topologia de base não será restabelecida se impedir o desempenho do sistema. Depois um novo problema é resolvido para encontrar o plano futuro da rede do sistema elétrico, com a adição de novas linhas de candidatas na topologia base modificada. A fim de encontrar um plano mais eficiente para a rede futura, a metodologia proposta é implementada usando a linguagem de modelagem para a programação matemática (AMPL) e solucionada usando o solver comercial CPLEX. A fim de validar a abordagem proposta e fazer alguma comparação com o método na literatura, três sistemas de testes são realizados, tais como: o sistema de 24-Bus IEEE teste com 41 linhas de candidatas, um estudos de casos práticos do sistema de 46-Bus do Sul do Brasil com 79 linhas de candidatas, e do sistema colombiano 93-Bus com 155 candidatas. Para sistemas de grande porte, a fim de facilitar a implementação do modelo matemático, uma estratégia é apresentada para reduzir o espaço de busca das barras em que a geração ou a demanda. Nos problemas de planejamento da expansão da transmissão geralmente nos deparamos com um problema de programação não-linear inteira mista (PNLIM) usando o modelo DC, o que torna impossível usar o solver linear ... / In this work and in order to solve the long-term transmission expansion planning problems, a novel mathematical model which is based on a change in the concept of expanding a transmission system is presented. In traditional transmission system expansion planning, only the additions of candidate lines are considered. In this work, a new concept of transmission system expansion planning is to find a new solution for the base topology where all the lines are temporarily disconnected and the implementation of these lines are reconsidered when they may return to their previous position. Therefore, the lines of the base topology will not be reconnected if they prevent the system performance. Afterwards a new problem is solved to find the future plan of the electrical system network with the addition of new candidate lines in the modified base topology. In order to find a more efficient plan for the future network, the proposed methodology is implemented using a Modeling Language for Mathematical Programming (AMPL) and solved using the commercial solver of CPLEX. In order to validate the proposed approach and make some comparison with the method in the literature, three test systems are conducted such as: the 24-Bus IEEE test system with 41 candidate lines, a practical case studies of 46-Bus South Brazilian system with 79 candidate lines, and the 93-Bus Colombian system with 155 candidates. For large-scale systems, in order to facilitate the implementation of the mathematical model, a strategy to reduce the search space of the buses in which the generation or demand has been presented. In the transmission expansion planning problems, usually we face with a mixed integer non-linear programming problem (MINLP) using the DC model, which make it impossible to use the linear solver of CPLEX. The strategy to overcome this problem is using the disjunctive linear model, which is a DC linear equivalent model. The ...

Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-30Bitstream added on 2014-06-13T19:47:48Z : No. of bitstreams: 1 vanderlinde_jb_me_ilha.pdf: 817450 bytes, checksum: f55727575f9ad09191bc30a0419b1f24 (MD5) / A presente pesquisa considera a análise teórica e a implementação computacional do algoritmo Dual Simplex Canalizado especializado na reotimização eficiente dos subproblemas gerados pelo algoritmo Branch and Bound para resolver problemas de Programação Linear Inteiro Misto. Juntamente com estes algoritmos é implementado o algoritmo Primal Simplex Canalizado para resolver o problema de Programação Linear inicial resultante do problema Programação Linear Inteiro Misto após desconsiderar a restrição de integralidade das variáveis. Estes algoritmos, adequadamente analisados e sistematizados são implementados através da linguagem computacional FORTRAN 77 e empregados no Planejamento da Expansão de Sistemas Transmissão modelados através do Modelo de Transportes que resulta em um problema de Programação Linear Inteiro Misto. / This research considers the theoretical analysis and computational implementation of the Dual Simplex algorithmfor Bounded Variables specializes in efficient re-optimization of sub-problems generated by the Branch and Bound algorithm to solve Mixed-Integer Linear Programming problems. Along with these algorithms has been implemented Primal Simplex algorithm for Bounded Variables to solve the initial Linear Programming problem result of a Mixed-Integer Linear Programming problem after relaxing the integrality of the variables. These algorithms has been adequately analyzed and implemented via the computer language FORTRAN 77. The methodology has been tested on the Transmission Network Expansion Planning based on a transportation model that results in a Mixed-Integer Linear Programming.

Made available in DSpace on 2014-06-11T19:22:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-22Bitstream added on 2014-06-13T18:49:35Z : No. of bitstreams: 1 lopes_vs_me_ilha.pdf: 457406 bytes, checksum: 6e25dd934aee860e9d139376c72ed631 (MD5) / O Problema do Planejamento da Expansão de Sistemas de Transmissão é um problema de otimização combinatória, cujo objetivo é buscar o atendimento de requisitos de cargas a custos mínimos de investimentos, percebendo um horizonte de longo prazo. A perspectiva do planejamento otimizado deve ser feita observando duas possiblidades: o planejamento estático e o planejamento multiestágio. No planejamento estático, o planjedor procura responder as questões onde e que tipos de elementos de transmissão precisam ser adicionados ou construídos para integrar a solução do sistema futuro. No entanto, quando a estratégia de expansão ótima abrange todo um período, o planejador deseja saber quando o circuito deve ser instalado, trata-se de um planejamento multiestágio. Em ambas alternativas, a resolução do problema do planejamento deve abranger duas etapas consecutivas: a modelagem matemática e a técnica de solução para resolver essa modelagem. Neste trabalho é apresentada uma proposta de planejamento estático utilizando aMetaheurística GRASP como técnica de solução para o problema do planejamento. / The Problem of Expansion Planning of Transmission Systems is a combinatorial optimization problem whose goal is to seek the assistance of cargo requirements at minimal cost investment, realizing a long-term horizon.The prospect of planning should be optimized observing two possibilities: planning static and multistage planning. In planning static, designer seeks to answer the questions where and what types of transmission elements need to be added or built to integrate the solution of the future system. However, when the optimal expansion strategy covers the whole period, the planner wants to know when the circuit must be installed, it is a multistage planning. In both alternatives, solving the problem of planning should cover two consecutive steps: mathematical modeling and solution technique to solve this modeling.This work presents a planning proposal using the static technique as GRASP metaheuristic solution to the problem of planning.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009 / Recently, due to concerns about the liberalization of electricity supply, deregulation and global impact on the environment, securing a reliable power supply has become an important social need worldwide To ensure this need is fulfilled, detailed investigations and developments are In progress on power distribution systems protection and the monitoring of apparatus which Is part of the thesis. The main objective of a protection schemes is mainly to keep the power system stable by isolating only the affected components or the section of the electricity network in which the fault has developed while allowing the rest of the network to continue operating. It is important to note that the protection equipment does not prevent faults from occurring, but it limits the damaging effect of the fault and protects other healthy equipment. This is only achieved if the protection system of the electrical network involved complies with the requirements and purpose of the electrical protection standards. These requirements include the Operational speed, Reliability, Security and Sensitivity. In conventional substations that are still existing Within the utilities networks, a number of long cables are then used to complete the links between substation equipment in order for them to communicate (hardwired). This method is uneconomical and is being phased out completely in the near future. Over the last few years a new standard for substation automation communication has been developed Within the International Electrotechnical Commission (IEC), the IEC 61850. This standard defines the integration requirements of multi-vendor compliant relays and other lED's for multiple protection schemes as well as control and automation techniques. In this particular thesis, Distribution protection is the area of interest, particularly the application of Time and Overcurrent protection schemes. A look into different protection alternatives and the application of new technologies for Electrical Power Distribution Systems that unify protection and control units so that they can be incorporated into Intelligent Substation as opposed to the most existing (conventional substation) is analyzed. The proposed algorithm has been verified through simulations of the CPUT and Eureka three phase power distribution systems. A testing Lab is also part of this thesis and Is meant for experiments as well as simulation performance in order to gain knowledge and skills for designing and engineer substations with lEG 61850 standards equiprnents. The results indicate that the reduction of copper wiring cable has increased and the communication speed has improved and simplified.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016. / Power grid and system protection advancement greatly depend on technological advances. Advent technologies like digital microprocessor type protective relays facilitate paradigm shifts, providing inimitable beneficial engineering adaptations. Phasor measuring technology provides one such technological advance. The onset and rapid development of the Phasor Measuring Unit (PMU) provides an excellent platform for phasor-based, power system engineering. Power transmission constitutes a critical section in the electric power system. The power system transmission lines are susceptible to faults which require instant isolation to establish and maintain consistent system stability. This research focuses on the study of transmission line protection based on P-Class synchrophasor measurements. The IEEE C37.238-2011 Precision Time Protocol (PTP) paradigm shift facilitates practical application of synchrophasors in protection schemes. Synchrophasor procession and accurate data alignment over wide areas support the hypothesis of a phasor-based transmission line differential protection. This research aims to directly implement P-Class synchrophasors in transmission line differential protection, employing synchrophasors to determine fault conditions and administer corresponding protective actions in wide area transmission lines. The research also aims to evaluate the operational characteristics of the synchrophasor-based transmission line differential protection scheme. The research deliverables include a laboratory scale Test-bench that implements the PMU-based transmission line differential protection scheme, and a differential protection utility software solution that follows guidelines specified by the C37.118-2011 standard for synchrophasors. The findings stand to evaluate performance of the PMU-based line differential protection scheme, verifying the protection model as an alternate, practical and feasible backup protection solution. The research deliverables include a synchrophasor-based current differential algorithm, software utility for implementing the PMU-based protection scheme and a Test-bench for concept and feasibility validation.

Orientadores: Christiano Lyra Filho, Aurélio Ribeiro Leite de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-17T10:40:56Z (GMT). No. of bitstreams: 1 Carvalho_SilviaMariaSimoesde_D.pdf: 1427390 bytes, checksum: 46a85c5d1759bf72fed5ba7508ef4f53 (MD5) Previous issue date: 2010 / Resumo: Os métodos de pontos interiores do tipo primal-dual são utilizados para minimizar os custos na geração e perdas na transmissão de energia elétrica no planejamento a curto-prazo da operação (prédespacho), em um sistema hidroelétrico com manobras previamente programadas. É realizado o estudo da estrutura matricial desse problema e das alterações que as manobras impõem ao sistema. Essas informações são exploradas para obter métodos especializados para a classe de problemas estudados. A solução de parte dos sistemas lineares em cada iteração depende somente de dados físicos e topológicos da rede. Algumas das matrizes associadas aos sistemas lineares podem ser decompostas antes de iniciar o processo iterativo, aumentando a velocidade de processamento. Resultados computacionais com sistemas testes do IEEE e sistemas reais brasileiros mostram que o método proposto é rápido e robusto, obtendo convergência em todos os testes viáveis à rede, aqui realizados / Abstract: The primal-dual interior point method is used to minimize the predispatch generation costs and transmission losses on short term operation planning of hydroelectric power systems with previously scheduled maneuvers. A matrix structure study is performed to consider the changes that occur in the system along the planning period. This information is used to develop specialized methods for the studied problem class. Some linear systems solved at each iteration depend only on network physical data and topology. Such matrices can be decomposed before starting the iterative process, speeding up the implementation. Numerical experiments with IEEE and real Brazilian power systems show that the proposed approach is fast and robust obtaining convergence in all performed tests / Doutorado / Automação / Doutor em Engenharia Elétrica