Esta tese apresenta uma estratégia de controle para gerenciar a potência entregue ou absorvida da rede, independente de características das cargas locais. Para atingir este objetivo é utilizado um inversor fonte de tensão (VSI) que funcionará semelhante a um sistema de geração distribuída (GD) ou como um filtro ativo. O VSI é controlado por meio de controladores clássicos em cascata, nos quais a malha interna é utilizado para estabilizar a corrente e a malha externa controla a tensão nos terminais de saída da GD. Para melhorar a resposta do VSI são colocados filtros ressonantes em paralelo ao controlador de tensão (P+RES). Além disso, as respostas dos filtros ressonantes são melhoradas através da utilização de um método adequado de discretização, no qual os coeficientes são alterados dinamicamente mediante a frequência de sincronismo produzido pelo algoritmo de sincronismo (PLL). O controle de potência apresenta duas estruturas de controle em malha fechada: uma para controlar a potência reativa através da rede pelo ajuste da amplitude da tensão da GD, e o outra para controlar a potência ativa, modificando o ângulo de defasagem entre as tensões da rede e as tensões GD. Por fim, um conjunto de simulações e resultados experimentais é apresentado para validar todas as propostas deste trabalho. / This thesis presents a control strategy to manage the power delivered to or absorbed from the grid, independently of the local load characteristics. To achieve this goal, a voltage source inverter (VSI) will work as a distributed generation system (DG) or according to active filter. The VSI will be controlled by means of a double cascade classical controller, in which the inner loop is used to stabilize the VSI output current and the outer loop controls the DG terminal voltage. To improve the response of the VSI, resonant filters are placed in parallel. Additionally, resonant filter dynamic responses are enhanced through the use of a proper discretization method, in which the coefficients are changed dynamically by means of the synchronism frequency produced by the phase-locked loop (PLL) algorithm. This study also exhibits two closed-loop structures: one to control the reactive power through the grid by adjusting the DG voltage amplitude, and the other to control the active power by modifying the angle of displacement between the grid and the DG voltages. Both power control structures operate adequately in decoupled operation mode, so that one has a faster dynamic response than the other. To verify all statements proposed in this thesis, a set of simulations and experimental results are presented.

A geração de energia elétrica através de grandes empreendimentos, sejam hídricos, térmicos ou nucleares demandam cada vez mais, grandes investimentos e longo período de tempo para início de operação. Em contrapartida, a demanda por este insumo básico para o desenvolvimento e manutenção da sociedade cresce cada vez a um ritmo mais acelerado. Visando atender a essa demanda, existe uma tendência global de instalar uma maior quantidade de pequenas unidades geradoras, ligadas diretamente à rede primária ou á rede secundária de distribuição. Tais unidades são usualmente denominadas de geração distribuída (GD) e dispersa (Gdd), respectivamente. Dentre as diversas vantagens obtidas por estas formas de geração poderá haver aumento da confiabilidade do sistema elétrico, a possibilidade de postergar investimentos necessários à rede de distribuição e a diversificação da matriz energética com maior possibilidade de uso de fontes renováveis de energia. A partir deste conceito foi desenvolvida uma metodologia, fundamentada na teoria de planejamento agregado, para identificar e quantificar potenciais unidades de geração distribuída na área da concessionária de distribuição de energia elétrica, avaliando os respectivos custos e benefícios de cada oportunidade. Por meio destes resultados é possível classificar e, conseqüentemente, priorizar as instalações com maior interesse tanto para o consumidor como, principalmente, para a concessionária local de distribuição de energia. De forma complementar, foram desenvolvidos modelos que possibilitem considerar a geração dispersa no planejamento da expansão dos sistemas de distribuição, bem como avaliar fatores que limitem sua expansão no Brasil. Este trabalho prioriza a análise sob ponto de vista da concessionária de energia elétrica, prática ainda não usual no Brasil, mas com grande potencial de aplicação. / The generation of electrical energy through large power plants (hydro, thermal or nuclear) demands, each time larger investments and high time to be ready for operation. In the other hand, the demand for electrical energy, that is so necessary for the development and maintenance of the society, is growing each day faster. Looking at the attendance of this demand, there is a global tendency to install a larger quantity of small generators, connected directly to the secondary or primary distribution grid of the electrical utility company. These units are known as distributed generation (GD) and dispersed generation (Gdd). Out of the many advantages through the use of distributed generation, the reliability growth in the electrical system, possibility of postpone necessary investments in the distribution network presents high importance and diversify the energetic matrix with the possibility of use renewable resources. From this concept, it was developed a routine, based on the theory of aggregated planning to identify and quantify potential units of distributed generation in the utility company area, evaluating the costs and benefits of each connection for the utility company. Through the results it will be possible the classification of the most interesting units, allowing the decision in conjoint between the consumer and the utility company. As a complement, it was developed mechanisms to make possible to consider disperse generation on the planning of distribution systems expansion. It was also made an evaluation of the factors that restrict the expansion of the disperse generation in Brazil. This thesis focus the analysis considering the utility company impacts, what is not used in Brazil but has a large potential of application.

abstract: The students of Arizona State University, under the mentorship of Dr George Karady, have been collaborating with Salt River Project (SRP), a major power utility in the state of Arizona, trying to study and optimize a battery-supported grid-tied rooftop Photovoltaic (PV) system, sold by a commercial vendor. SRP believes this system has the potential to satisfy the needs of its customers, who opt for utilizing solar power to partially satisfy their power needs. An important part of this elaborate project is the development of a new load forecasting algorithm and a better control strategy for the optimized utilization of the storage system. The built-in algorithm of this commercial unit uses simple forecasting and battery control strategies. With the recent improvement in Machine Learning (ML) techniques, development of a more sophisticated model of the problem in hand was possible. This research is aimed at achieving the goal by utilizing the appropriate ML techniques to better model the problem, which will essentially result in a better solution. In this research, a set of six unique features are used to model the load forecasting problem and different ML algorithms are simulated on the developed model. A similar approach is taken to solve the PV prediction problem. Finally, a very effective battery control strategy is built (utilizing the results of the load and PV forecasting), with the aim of ensuring a reduction in the amount of energy consumed from the grid during the “on-peak” hours. Apart from the reduction in the energy consumption, this battery control algorithm decelerates the “cycling aging” or the aging of the battery owing to the charge/dis-charges cycles endured by selectively charging/dis-charging the battery based on need. ii The results of this proposed strategy are verified using a hardware implementation (the PV system was coupled with a custom-built load bank and this setup was used to simulate a house). The results pertaining to the performances of the built-in algorithm and the ML algorithm are compared and the economic analysis is performed. The findings of this research have in the process of being published in a reputed journal. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2018

Esta tese apresenta uma estratégia de controle para gerenciar a potência entregue ou absorvida da rede, independente de características das cargas locais. Para atingir este objetivo é utilizado um inversor fonte de tensão (VSI) que funcionará semelhante a um sistema de geração distribuída (GD) ou como um filtro ativo. O VSI é controlado por meio de controladores clássicos em cascata, nos quais a malha interna é utilizado para estabilizar a corrente e a malha externa controla a tensão nos terminais de saída da GD. Para melhorar a resposta do VSI são colocados filtros ressonantes em paralelo ao controlador de tensão (P+RES). Além disso, as respostas dos filtros ressonantes são melhoradas através da utilização de um método adequado de discretização, no qual os coeficientes são alterados dinamicamente mediante a frequência de sincronismo produzido pelo algoritmo de sincronismo (PLL). O controle de potência apresenta duas estruturas de controle em malha fechada: uma para controlar a potência reativa através da rede pelo ajuste da amplitude da tensão da GD, e o outra para controlar a potência ativa, modificando o ângulo de defasagem entre as tensões da rede e as tensões GD. Por fim, um conjunto de simulações e resultados experimentais é apresentado para validar todas as propostas deste trabalho. / This thesis presents a control strategy to manage the power delivered to or absorbed from the grid, independently of the local load characteristics. To achieve this goal, a voltage source inverter (VSI) will work as a distributed generation system (DG) or according to active filter. The VSI will be controlled by means of a double cascade classical controller, in which the inner loop is used to stabilize the VSI output current and the outer loop controls the DG terminal voltage. To improve the response of the VSI, resonant filters are placed in parallel. Additionally, resonant filter dynamic responses are enhanced through the use of a proper discretization method, in which the coefficients are changed dynamically by means of the synchronism frequency produced by the phase-locked loop (PLL) algorithm. This study also exhibits two closed-loop structures: one to control the reactive power through the grid by adjusting the DG voltage amplitude, and the other to control the active power by modifying the angle of displacement between the grid and the DG voltages. Both power control structures operate adequately in decoupled operation mode, so that one has a faster dynamic response than the other. To verify all statements proposed in this thesis, a set of simulations and experimental results are presented.

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.

O crescente número de geradores distribuídos conectados em redes de distribuição de energia elétrica é uma realidade dos sistemas elétricos de todo o mundo. Embora a política atual seja desconectar os geradores distribuídos do sistema elétrico de potência (SEP) caso ocorra uma falha na rede da concessionária, conforme preconizam os principais guias técnicos nacionais e internacionais, o módulo 3 dos Procedimentos de Distribuição de Energia Elétrica no Sistema Elétrico Nacional (PRODIST) mostra-se favorável à operação ilhada, pois afirma que este tipo de operação pode ser realizado em comum acordo entre as centrais geradoras de energia e o Operador Nacional do Sistema Elétrico (ONS), permitindo alcançar uma maior disponibilidade no fornecimento de energia. No entanto, para que a operação ilhada seja possível e possa ser praticada de forma segura, o ilhamento intencional precisa superar alguns desafios, dentre os quais estão aqueles relacionados ao sistema de proteção da rede de distribuição, tais como: coordenação indevida de dispositivos de proteção, perda da sensibilidade da proteção, abertura inadequada de fusíveis e religamentos automáticos fora de sincronismo. Portanto, este trabalho avalia o impacto da geração distribuída (GD) sobre o sistema de proteção de sobrecorrente de uma rede de distribuição operando ilhada. A ideia principal é dividir a rede em regiões delimitadas pelos dispositivos de proteção existentes, para em seguida, adequá-los à nova situação operacional, certificando se os ajustes propostos atendem ao comportamento síncrono e estável do sistema de geração por meio de uma análise de estabilidade transitória. Propõe-se então um conjunto de procedimentos para tomada de ações que permitam readequar o sistema de proteção de sobrecorrente existente à operação ilhada. Os resultados obtidos demonstram que a inibição do religamento automático e da curva de atuação instantânea acrescida de reajustes nas curvas temporizadas dos relés e religadores, melhoraram a coordenação e seletividade da rede operando ilhada. / The growing number of distributed generators connected to electricity distribution networks is a reality of electrical systems throughout the world. Although the current policy is to disconnect the distributed generators from the electric power system (EPS) in the event of loss of mains, as required by main national and international technical guides, the module 3 of the Procedures for Electric Power Distribution in the Electric National System (PRODIST) shows itself in favor of islanded operation, it states that this type of operation can be carried out in agreement between power generation plants and the National Electric System Operator (ONS), allowing achieve larger availability in energy supply. However, to make the islanded operation possible and safe, the intentional islanding must overcome some challenges, among which are those related to the protection system of the distribution network, such as improper coordination of protective devices, loss of protection sensitivity, inadequate opening of fuses and automatic reclosing out of synchronism. Therefore, this work evaluates the impact of distributed generation (DG) on the overcurrent protection system of a distribution network operating islanded. The main idea is to divide the network into regions bounded by existing protection devices, to then adapt them to the new operational situation, making sure that the proposed adjustments meet the synchronous and stable behavior of the generation system by means of a transient stability analysis. Thus, a set of procedures is proposed to indicate actions that allow readjusting the existing overcurrent protection system to the islanded operation. The results demonstrate that the inhibition of automatic restart and of the instantaneous operating curve plus adjustments in time delay curves of relays and reclosers, improved the coordination and selectivity of the network operating islanded.

Oregon utilities are replacing their portfolios of traditional fossil fuel generation with renewable generating sources. Stepping away from carbon-producing energy will leave a deficit of on-demand power, resulting in decreased reliability. To overcome these technical challenges, utilities must maximize the use of their present dispatchable resources. One such resource is the Portland General Electric (PGE) Dispatchable Standby Generation Program (DSG), which is an aggregated 105 MWs of distributed generation (DG). These resources are brought on-line when there is a critical need for power. Resources are added to the program if a transfer trip scheme is in place or a modeling study reveals that the feeder load is at least three times the generator capacity. If the load-to-capacity ratio were lower, more assets could be added to the DSG program. To investigate the impacts of lowering the DG load-to-capacity ratio on existing distribution feeders, we use Open-Source Distribution System Simulator (OpenDSS). We modeled the Oxford Rural feeder by converting a utility CYME database to instantiation files using several MATLAB programs. A MATLAB control program varies the load-to-capacity ratio of the OpenDSS feeder model and monitors the generator behavior immediately following a fault. We analyzed the results to determine the ideal load-to-capacity ratio that prevents unintentional islanding. The results show that the instantaneous (50) relay element settings dictate both the minimum load-to-capacity ratio and the maximum DG capacity. The present three-to-one ratio is very conservative and can be reduced. Additional dispatchable resources include a five MW battery-inverter system currently used as grid-back up. The battery is grid-tied to a 12.4 kV feeder making it an ideal candidate for conservation voltage reduction (CVR). Using the same feeder model, we investigated the effects of lowering the system voltage to the allowable minimum using injections of reactive power. A lower system voltage reduces the load at peak times. Conversely, increasing the voltage prevents generation conflicts. To determine the benefit of CVR by VAr-injection on the Oxford Rural feeder, we created a MATLAB optimization program to output the optimal feeder voltage for reduced system power. We use a Simulink feedback model to determine the appropriate reactive power needed to achieve the voltage change. We analyze the system model to reveal that the feeder is ideal for CVR but the system capacity must be increased to achieve the maximum power reduction.

In this dissertation, we propose a novel distributed approach to the control of generators in the electric grid. Specifically, we consider the problem of the optimal economic dispatch of generator; we present a simple, distributed algorithm, which adjusts the power-frequency set-points of generators to correct for power imbalances arising from generation and load fluctuations. In this algorithm each generator independently adjusts its real-power output based on its estimate of the aggregate power imbalance in the network; such as an estimate can be independently obtained by each generator through local measurements of the frequency deviation on the grid. Eventually, over the course of network operation, the distributed algorithm achieves the equal-marginal-cost power allocation among generators while driving the power imbalance exponentially to zero. In the absence of power losses, we prove the eventual optimality of the distributed algorithm under mild assumptions (strict convexity and positivity of cost functions) and present simulation results to compare its performance with traditional (centralized) dispatch algorithms. Furthermore, we present numerical simulation results that show that the distributed algorithm performs well even in the presence of power losses and other constraints. We argue that distributed control methods are especially attractive for electric grids with smart meters and other advanced capabilities at the end node and grids with high penetration of alternative energy generators and we identify interesting open problems for future work in this area.

Governments and utility organizations around the world have mandated and provided incentives for new distributed renewable energy generation (DREG) capacity, and market projections indicate strong growth in distributed renewable energy generation installations in the coming years. New distributed renewable energy generation utilities, by definition, will be primarily located in built environments near consumers; these utilities are often planned and designed by landscape architects, yet no evidence-based, distributed renewable energy generation research is explicitly done by landscape architects or recognizes the role landscape architects play in planning and designing these spaces. The research and analysis provided by this study indicates that distributed renewable energy generation lacks a strong foundation as an independent concept which could benefit from clear broad phraseology linked to organized sub-terms/phrases for specific forms of DREG, that there has been some research done on topics familiar to landscape architects, that more needs to be done to meet important research questions and recommendations already posed, and that landscape architects are positioned to contribute to future distributed renewable energy generation research.

<p>This thesis tries to explain the changes in the control of power electronic converters that are possible by the use of communication. Many of the renewable energy sources such as photovoltaic panels are geographically dispersed. The power rating per generator is therefore typically low. If this kind of energy source should dominate an electrical grid, the number of generators must be high. There should also be means of controlling this large number of generators simultaneously and safely. The cost of safe communication may be too high compared to the power contribution of a single generator. The Internet offers a low-cost solution, but it cannot guarantee real-time properties. Similarly to the Internet itself, it is shown how communication errors can be detected and handled in a safe manner by the end-system, in this case the generator. The generator can detect a communication timeout, and change control algorithms in order to guard itself and the connected electricity grid. When necessary, it can also disconnect and work as a local standalone power supply. In order to be able to supply all kinds of loads, the generator (in this case an inverter) is primarily voltage controlled. This results in challenges concerning current distortion. The use of feed-forward for cancellation of common grid voltage harmonics is discussed, simulated and measured. An anti-islanding algorithm for voltage controlled inverters is also developed, simulated and measured in this thesis. A DC/DC-converter for optimized connection of a photovoltaic panel is built, exploiting the photovoltaic panel properties to reduce the size and the losses significantly. Although most contributions are connected to details and parts of the system, the interactions between communication and control are emphasized.</p>