National Science Foundation Grant no. SIA73-07871 A02

Made available in DSpace on 2016-05-17T16:51:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-27. Added 1 bitstream(s) on 2016-05-17T16:54:38Z : No. of bitstreams: 1 000864195.pdf: 1444139 bytes, checksum: 4c71dd66b98863205682d0d369ea0cfa (MD5) / Este trabalho apresenta um modelo de programação cônico de segunda ordem inteiro misto (MPCSOIM) e um modelo de programação linear inteira mista (MPLIM) para resolver o pro- blema de expansão de sistemas de distribuição de energia elétrica (SDEE) a longo prazo com uma abordagem dinâmica, considerando os seguintes planos: aumento da capacidade de subes- tações existentes, a instalação de novas subestações, a alocação de bancos de capacitores e/ou reguladores de tensão, instalação de novos circuitos e/ou recondutoramento dos existentes e, modificação, se for necessário, da topologia do sistema. O objetivo é minimizar o valor pre- sente dos custos de investimento e operação do SDEE dentro de um horizonte de planejamento estabelecido. O modelo de natureza linear usa uma técnica de linearização e uma aproxima- ção para transformar o problema original em um MPLIM, enquanto o modelo cônico é obtido transformando as restrições não lineares em restrições quadráticas devido à equivalência das soluções do modelo de programação não linear (MPNL) e o modelo de programação cônico de segunda ordem (MCSO) na abordagem do cálculo do ponto de operação em regime perma- nente (PORP) dos sistemas de distribuição. A fim de testar e verificar os modelos propostos utilizou-se um sistema teste de 18-nós e um sistema teste de 24-nós / This paper presents a mixed integer second-order cone programming model (MISOCPM) and a mixed integer linear programming model (MILPM) to solve the problem of expansion of electrical energy distribution systems (EDS) on a long-term dynamic approach, considering: increasing the capacity of existing substations, installing new substations, allocation of banks of capacitors and/or voltage regulators, installation of new circuits and/or recondutoring of exis- ting circuits and, if necessary, modification of the topology of the system. The objective is to minimize the present value of the investment and operation costs of EDS within a given plan- ning horizon. The linear model uses a linearization technique and an approach to transform the original problem in a MILPM. The conical model is obtained by transforming nonlinear cons- traints in quadratic constraints given the equivalence of solutions of non-linear programming model (NLPM) and the second-order cone programming model (SOCPM) in addressing the calculation of the operating point in steady state (OPSS) distribution systems. In order to test and verify the proposed models used an 18-nodes system and a 24 nodes system

Doctor of Philosophy / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / Active consumers who engage in energy consumption, production, storage and provide ancillary services in a dynamic and interactive manner will be an integral part of the future grid. Firstly, this dissertation models and analyzes the interaction between active consumers and aggregators with a specific focus on consumer actions in response to real-time electricity pricing and the resulting impact on grid voltage. A unique prospect theory based consumer behavior model is introduced. This model captures wide range of consumers each with their individual preferences by modeling the interaction between the active consumers and the aggregator as a Stackelberg game. However, unlike existing game theoretic efforts that assume rational behavior of consumers, the prospect theory based models systematically incorporate realistic consumer behavior including irrationality. Secondly, this dissertation develops probabilistic voltage sensitivity analysis. In contrast to prior approaches that limit themselves to economic aspects, the proposed techno-economic perspective provides an understanding of the impact of large scale penetration of active consumers on the physical grid. Most current studies are scenario-based, and derived results are scenario specific. Determining the impact of spatially distributed active consumers with temporally variable behavior requires investigation of a large number of scenarios, which is computationally intractable using current iterative power flow algorithms. This work provides a new analytical method of voltage sensitivity analysis that allows for stochastic analysis of change in grid voltage due to change in consumer behavior (load and generation choices). This work first derives an upper bound for change in voltage at a particular bus due to change in power consumption at other buses in a radial distribution network. Next, this bound is used to derive the probability distribution of change voltage at a bus due to randomly changing power consumption/injection of random spatial distribution of the active consumers. This upper bound is also used to develop an algorithmic approach to identify the dominant influencer of voltage fluctuations in the power distribution system. Thirdly, security and stability aspects of transactive energy market based power distribution system is investigated. Specifically, the impact of attacks on pricing/load signals on the physical grid is quantified. This work models the interaction between real-time electricity price and total energy demand in the form of a discrete time non-linear autonomous dynamical system. Equilibrium electricity price and energy demand associated with this coupled dynamical system is derived and conditions for bounded input bounded output (BIBO) stability are identified. Then, a BIBO stable algorithm to design real-time electricity pricing scheme from a techno-economic perspective is developed. Finally, the impact of various level of false data injection (FDI) attack on price of electricity, demand and distribution system voltage is investigated. This dissertation shows that impact of FDI attack on electricity prices is more severe than an attack on electricity demand.

Made available in DSpace on 2014-12-02T11:16:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-24Bitstream added on 2014-12-02T11:20:51Z : No. of bitstreams: 1 000800405.pdf: 913898 bytes, checksum: a1bea0465e9b87954e4a60a61ce3e65b (MD5) / Neste trabalho é realizada uma análise teórica e a implementação computacional de um algoritmo de Busca Dispersa especializado para resolver o problema de planejamento da expansão de sistemas de transmissão (PPEST) de energia elétrica estático. O problema de planejamento consiste em determinar entre um conjunto de circuitos candidatos, aqueles que quando forem incorporados ao sistema apresentarem o menor custo de investimento possível. Este problema é considerado complexo e difícil de ser resolvido por ser um problema não linear inteiro misto, altamente ilhado, envolvendo “explosões” combinatórias. A meta-heurística de busca dispersa é um algoritmo evolutivo que se propõe a combinar soluções de qualidade e de diversidade do espaço de busca. O algoritmo de busca dispersa desenvolvido apresentou-se altamente eficiente para encontrar soluções de ótima qualidade para todos os problemas testados comparados com a literatura consultada, especializada na área. A garantia da diversidade oferecida pelo algoritmo é adicionada intencionalmente como forma de evitar, ou mesmo avançar por ótimos locais. Outro fato importante é que o método opera sobre um conjunto reduzido de soluções do espaço de busca criteriosamente gerado, que faz reduzir significativamente o número de combinações que são realizadas. Rotinas geradas com a utilização de algoritmos heurísticos construtivos gulosos de Garver e Villasana-Garver-Salon para modelos como o de Transportes e o modelo DC no PPEST apresentaram alto desempenho neste trabalho. Uma perturbação controlada nos custos de instalação das linhas de transmissão foi decisiva para que o processo de geração de soluções (factíveis, diversas e/ou com qualidade) fosse altamente eficiente, sendo possível encontrar o ótimo global em alguns problemas ainda nesta etapa de geração de soluções. Mecanismos de melhoramento local aplicados ... / This work presents a theoretical analysis and computational implementation of a specialized Scatter Search algorithm to solve the static transmission network expansion planning (TNEP) problem of electric power systems. The objective of such planning problems is to determine a set of circuits among the candidates in which not only satisfy the demands but also the minimum investment cost is at hand. This problem is considered as a complex mixed integer nonlinear programming (MINLP) problem that has a lot of local optimum problem. The scatter search is an evolutionary method with the objective of maintaining a set of diverse and high-quality candidate solutions. The proposed scatter search algorithmhas been applied in engineering optimization problems especially in electric power system problems and has presented high quality solutions. The diversity sets ensure to avoid getting trapped in a local optimum. Another important factor is that the proposed methodology reduces the search space and consequently the number of combinations is reduced. In this work, a high quality solution of TNEP is obtained using the greedy constructive heuristic algorithms such as Garver, and Villasana-Garver-Salon that work based on Transport model and DC model respectively. In this work, in order to generate the initial solutions, a controlled disturbance has been added in the costs of the transmission lines in order to obtain diverse and high quality solutions that lead to find the global optimum for some problems even in the initial generation step. Moreover, the proposed scatter search algorithm presents a local improvement phase during the implementation. In order to show the effectiveness of the proposed algorithm, 5 case studies are conducted such as Garver 6-bars and 15 branches , IEEE 24-bars and 41 branches , South Brazilian 46-bars and 79 branches, Colombian 93-bars and 155 branches, and the North-Northeast 87-bars ...

Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-30Bitstream added on 2014-06-13T19:28:06Z : No. of bitstreams: 1 rupolo_d_me_ilha.pdf: 1818136 bytes, checksum: 666bb79c31569f91ad006d6801bf47c0 (MD5) / Neste trabalho propõe-se um algoritmo baseado na meta-heurística busca dispersa para o problema de reconfiguração de redes de distribuição de energia elétrica radiais, considerando como sistema de codificação uma estrutura denominada representação nó profundidade (RNP). O problema é modelado como não linear inteiro misto e considera como objetivo principal minimizar as perdas de potência ativa nos alimentadores do sistema de distribuição. Utiliza-se neste trabalho o modelo de cargas com potência constante, como também o modelo exponencial de cargas. O algoritmo proposto é implementado em linguagem de programação C++ e testado em quatro sistemas conhecidos na literatura, 14, 84, 136 e 202 barras. A partir dos resultados obtidos, verifica-se o bom desempenho do algoritmo, pois é capaz de gerar soluções de boa qualidade atendendo a todas as restrições físicas e operacionais do problema. / This work proposes a scatter search algorithm to solve the electric power distribution system reconfiguration problem, considering the encoding system node depth representation. The problem is a mixed-integer nonlinear programming and the objective is to minimize the real power losses in the distribution system. It is used in the work load model with constant power, but also exponential model load. The proposed algorithm is implemented in C + +. The validity of the methodology is verified through four commonly case studies such as 14, 84, 136 and 202 bus system. Results show the effectiveness and good performance of the proposed algorithm, where it obtains the good quality solution satisfying the operational and physics constraints of problem.

Made available in DSpace on 2014-10-09T12:50:30Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:49Z (GMT). No. of bitstreams: 1 00045.pdf: 1150397 bytes, checksum: fd8a86947b37fabf9aa8ff7b1e99d2a9 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

Made available in DSpace on 2016-09-27T13:40:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-26. Added 1 bitstream(s) on 2016-09-27T13:45:21Z : No. of bitstreams: 1 000868828.pdf: 1398254 bytes, checksum: b44031133d83ed0f7078fb32d0787427 (MD5) / Neste trabalho, propõe-se um algoritmo baseado na meta-heurística busca tabu para o problema de restauração de redes de distribuição de energia elétrica radiais com geração distribuída, considerando como sistema de codificação uma estrutura denominada representação nó-profundidade (RNP). O problema é modelado como não linear inteiro misto e considera os principais objetivos da restauração de redes de distribuição: minimizar número de consumidores sem fornecimento de energia elétrica e o número de chaveamentos. Propõe-se, também, uma sequência lógica de chaveamentos que garante os aspectos operacionais. O algoritmo desenvolvido foi implementado em linguagem de programação C++ e testado em sistemas de distribuição de 136 e 7052 barras / This work proposes a methodology based in the meta-heuristic tabu search to distribution power system restoration considering distributed generators installed on the system, using the encoding system node depth representation. The problem is established as a mixed-integer nonlinear programming taking into account the mainly goals: to minimize both the number of consumers without supply and the number of switching. This work also proposes a logic sequence of switching operations, taking care of operational issues. The proposed algorithm was implemented in C++ programming language and tested in a 136 and a 7052 bus distribution systems

Thesis submitted in partial fulfilment of the requirements for the degree Magister Technologiae: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2013 / The space environment is characterised by harsh radiation, extreme temperatures and vacuum. Electronics subsystems for satellite applications are designed to be fault tolerant and robust enough to survive this environment. A power distribution module (PDM) for a CubeSat nanosatellite application is developed here, with the aim to distribute power to CubeSat subsystems reliably. The PDM prototype is carefully designed with reference to an extensive literature study. The study dwells on the low Earth orbit (LEO) space environment, critically identifying radiation sources and temperature ranges in the LEO. The study further investigates traditional analogue techniques of logic circuit design using bipolar junction transistors (BJTs) which are known for their higher tolerance to radiation sources as compared to recent integrated circuits (ICs). Careful consideration is given to different ways of designing a fault tolerant system. The study specifically looks at redundant circuit design within the limitations of weight and space of a nanosatellite. Possible electrical faults in power systems are identified, which include over-currents, over-voltages, over-temperatures, inrush currents and latchup. This study shows that identified faults generally are overcurrents. A power switch is included in each power distribution channel to trip the current in case a faulty condition is detected. The PDM is designed to have eight power output distribution channels to allow a subsystem load to connect to more than one channel, thereby meeting its power requirements. The PDM power channels are designed identically. Upon application, current limits are selected by a two-resistor divider circuit and connectors are used to connect to a required voltage bus at manufacturing time. The system’s functionality is tested and verified using an Arduino development board interfaced to all I2C devices as a master node, typically the on-board computer (OBC) in a real satellite mission. The system’s functionality in a Gamma irradiated laboratory environment is verified to perform as required. The PDM system is further tested in a temperature cycled chamber from -31°C to 61°C. The system survived the entire eight hour test duration of two cycles. It is observed that the system is fault tolerant to radiation sources up to 10 krad and the temperature limits mentioned. The PDM system is recommended as an additional module to the CubeSat electrical power subsystem (EPS), thereby improving the reliability of the power subsystem. Keywords: CubeSat, power channel, module, radiation, reliability, efficiency, I2C, prototype.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2013 / Harmonic voltages and currents in distribution networks are on the increase in recent times due to the introduction of a proliferation of electronic controlled devices such as variable speed drives. These non-linear devices improve efficiency but distort the supply waveforms. To address the harmonic issues, harmonic filters are used to mitigate distortion levels and prevent damage. These harmonic filters are commonly found at medium voltage levels in power systems. The problem is that knowledge from the design to commissioning stages of these medium voltage harmonic filters are neither well developed nor adequately documented. The aim of this research is to investigate and expound upon the process whilst taking into account all the factors involved throughout the process from bringing such a filter into operation in the real world. Medium voltage harmonic filters are usually the open rack type found in outdoor installations. Capacitors and reactors are the main components used in the construction of such harmonic filters and in some instances resistors are also used. The physical size and spacing of such components determines the construction layout area and how this is done in practice warrants being researched and explained in this thesis. In order to make these factors explicit, a methodology is developed from design, to installation and commissioning and is applied to two networks which are used to prove that the developed methodology is applicable for the different types of harmonic filters designed. The network voltage levels are also different, thus implying that the components will have different design factors. The final arrangements of the harmonic filters are later drawn and shown in three-dimension (3D) as per dimensions. The 3D figures are a further contribution as the design is taken from theory and is ultimately implemented into an installation and construction layout for erection at site. Interviews and surveys are conducted with specialists in industry dealing with harmonic filter applications and the results are analysed as part of implementation of the developed methodology. The design, installation and construction phases are documented and shown to be effective in application and the work disclosed in this thesis will help newcomers to this specialised field and is recommended for use in industry.

Orientador: Marina Lavorato de Oliveira / Banca: José Roberto Sanches Mantovani / Banca: Eduardo Nobuhiro Asada / Resumo: Este trabalho apresenta um modelo de programação cônico de segunda ordem inteiro misto (MPCSOIM) e um modelo de programação linear inteira mista (MPLIM) para resolver o pro- blema de expansão de sistemas de distribuição de energia elétrica (SDEE) a longo prazo com uma abordagem dinâmica, considerando os seguintes planos: aumento da capacidade de subes- tações existentes, a instalação de novas subestações, a alocação de bancos de capacitores e/ou reguladores de tensão, instalação de novos circuitos e/ou recondutoramento dos existentes e, modificação, se for necessário, da topologia do sistema. O objetivo é minimizar o valor pre- sente dos custos de investimento e operação do SDEE dentro de um horizonte de planejamento estabelecido. O modelo de natureza linear usa uma técnica de linearização e uma aproxima- ção para transformar o problema original em um MPLIM, enquanto o modelo cônico é obtido transformando as restrições não lineares em restrições quadráticas devido à equivalência das soluções do modelo de programação não linear (MPNL) e o modelo de programação cônico de segunda ordem (MCSO) na abordagem do cálculo do ponto de operação em regime perma- nente (PORP) dos sistemas de distribuição. A fim de testar e verificar os modelos propostos utilizou-se um sistema teste de 18-nós e um sistema teste de 24-nós / Abstract: This paper presents a mixed integer second-order cone programming model (MISOCPM) and a mixed integer linear programming model (MILPM) to solve the problem of expansion of electrical energy distribution systems (EDS) on a long-term dynamic approach, considering: increasing the capacity of existing substations, installing new substations, allocation of banks of capacitors and/or voltage regulators, installation of new circuits and/or recondutoring of exis- ting circuits and, if necessary, modification of the topology of the system. The objective is to minimize the present value of the investment and operation costs of EDS within a given plan- ning horizon. The linear model uses a linearization technique and an approach to transform the original problem in a MILPM. The conical model is obtained by transforming nonlinear cons- traints in quadratic constraints given the equivalence of solutions of non-linear programming model (NLPM) and the second-order cone programming model (SOCPM) in addressing the calculation of the operating point in steady state (OPSS) distribution systems. In order to test and verify the proposed models used an 18-nodes system and a 24 nodes system / Mestre