M.Tech. (Electrical and Electronic Engineering) / With the increasing use of nonlinear loads in power systems, harmonic pollution becomes more frequent with disastrous consequences on the electrical network and other loads. Harmonic currents cause problems such as system resonance, protective relays and switchgear malfunction, communication interference, incorrect meter, equipment and process failure, over heating of transmission and distribution systems, insulation degradation and power transformer failure. It appears therefore absolutely essential to determine the current profile of the loads connected to the same Point of Common Coupling (PCC). This study aims to assess a distorted power system in order to determine the characteristics components of distorted waveforms (DC components, fundamental and harmonics components), and to quantify the respective distortion contributions in the power network. The numerical method is applied to analyse the current waveforms captured with the aid of the digital scope meter (DSO) 1200 series at different sections of the network. The power network under study is designed, constructed and analysed with the MatLab/Simulink 7.0 package. In both methods, the Individual Harmonic Distortion (IHD) and the current total harmonic distortion (ITHD) for the line, the non-linear and linear loads are computed for the harmonic components 5th, 7th, 11th and 13th. The results showed that for the analysis of the power system, numerical analysis based on the resultant harmonic curve method and the MatLab/Simulink as applied to the network all converged to highlight that harmonic components appear both on the line, the PCC and the linear load. This is due to the fact that the converter characteristic harmonics (5th, 7th, 11th, 13th…) are found in the network components (line, PCC, linear load…). The resultant harmonic curve method indicated a randomly distributed percentage IHD in different sections of the network for harmonic orders higher than 7th, whereas the Matlab/Simulink results normally show a non-uniform decay pattern of the IHD as the harmonic order increases within the respective section of the network.

Electricity is a perishable commodity; once it is generated it needs to be consumed or stored. Electric energy storage provides both power and energy capacity. Power capacity applications reduce the need for generation, while energy capacity allows for energy consumption to be decoupled from generation. Previous research was done to develop an algorithm for determining the power (MW) and energy (MWh) capacities of a battery energy storage system (BESS) to mitigate the adverse impacts of high levels of photovoltaic (PV) generation. The algorithm used a flat feeder profile, and its performance was demonstrated on the equinoxes and solstices. Managing feeder power leads to fewer voltage fluctuations along the length of the feeder, potentially mitigating load management issues caused by variability of renewable generation and load profile. These issues include lighting flicker, compressor seizing, equipment shut-off, loss of motor torque, frequent transformer tap changes and even voltage collapse due to loss of reactive power support. The research described in this thesis builds on this algorithm by incorporating a smoothed feeder profile and testing it over an entire year. Incorporating a smoothing function reduces the requisite BESS energy capacity necessary to provide firming and shaping to accommodate the stochastic nature of PV. Specifically, this method is used to conduct a year-long study on a per second basis, as well as a one-minute basis, for a distribution feeder. Statistical analytical methods were performed to develop recommendations for appropriately sizing the BESS. This method may be used to determine the amount of PV generation that could be installed on a distribution feeder with a minimal investment in the BESS power and energy capacities that would be required to manage the distribution feeder power. Results are presented for PV penetration levels of 10%-50% of the distribution feeder capacity and show that the use of a smooth feeder profile reduces the required energy capacity by a minimum factor of 10 when compared to a flat feeder profile. Results indicated that it is sufficient to have a one-minute sampling rate, as it provides the necessary granularity to model cloud-induced fluctuations. This method can be applied to any distribution feeder where a load profile and a PV profile are available.

The exponential power (EP) distribution is a very important distribution that was used by survival analysis and related with asymmetrical EP distribution. Many researchers have discussed statistical inference about the parameters in EP distribution using i.i.d random samples. However, sometimes available data might contain only record values, or it is more convenient for researchers to collect record values. We aim to resolve this problem. We estimated two parameters of the EP distribution by MLE using upper record values. According to simulation study, we used the Bias and MSE of the estimators for studying the efficiency of the proposed estimation method. Then, we discussed the prediction on the next upper record value by known upper record values. The study concluded that MLEs of EP distribution parameters by upper record values has satisfactory performance. Also, prediction of the next upper record value performed well

Efficiency analysis in the public sector assesses the performance of municipal and government entities in their provision of services to the public. South Africa, in particular, has experienced a large degree of negative feedback with respect to the ability of the government and its municipal departments to provide basic services to citizens. This has led to a number of service delivery protests throughout the country. To remedy this, the ability of the municipality to provide basic services needs to be assessed in order for improvements to be made. A first step in this process would be to determine the efficiency with which municipalities are providing these services. This study focuses on a particular municipal service, namely electricity distribution. Primarily, the efficiency with which municipalities provide electricity to consumers is determined. This is achieved using the parametric cost frontier approach, which is appropriate since municipalities aim to reduce the costs incurred in distributing electricity. The municipalities are compared to a frontier (theoretical best practice) from which inferences on their performances can be made. Those municipalities whose performances are not optimal, deviate from the frontier. The deviations (errors) are then assumed to be caused by two factors, namely stochastic random noise and inefficiency. This composition accounts for effects for which municipalities cannot control (stochastic random noise) and those for which it can (inefficiency). The parametric nature of the cost frontier approach allows for distributional assumptions to be made on these factors. Stochastic random noise is always assumed to be normally distributed, while inefficiency is assumed to be one-sided and positively skewed.

There is growing interest in research and development activities on biomass gasification technologies as an alternative to fossil fuels technologies. However not much has been done in terms of technology transfer, particularly in under-developed and developing countries such as South Africa. This is mainly because of the lack of resources such as funding. Most parts of the under-developed and developing countries fall within rural areas and semi-urban centers, which are endowed with biomass resources. South Africa has a number of sawmill operators who generate tons of biomass waste during processing of timber; the large proportion of this is burned in furnaces as a means for waste management while a very small proportion is collected and used by people in rural areas for cooking their food. The majority of people in rural areas of South Africa are either unemployed or cannot afford the current energy services. The main aim of this research was to establish the viability of electricity generation for community economic development through biomass gasification, specifically using the locally designed System Johansson Biomass Gasifier™ (SJBG), and to establish the efficiency of the gasifier and associated components with a view of developing strategies to enhance it. The study established the technical and economic feasibility of using the SJBG to generate low-cost electricity for community empowerment. The study also developed strategies to improve the particle collection efficiency of the cyclone. In addition to this, a low-cost gas and temperature monitoring system capable of monitoring gas and temperature at various points of the gasifier was developed. The system was built from three Non- Dispersive Infrared gas sensors, one Palladium/Nickel gas sensor and four type K thermocouples. The study also investigated the impact of fuel compartment condensates on gasifier conversion efficiency. This is an area that has not yet been well researched since much has been done on energy recovery using combined heat and power applications that do not utilize the energy in condensates because these are produced in the gasifier and drained with chemical energy stored in them. The study established that the condensates do not have a significant impact on efficiency.

D.Phil / The prediction of the expected transmission network loads as required for transmission network power flow studies, has become very important and much more complex than ten to twenty years ago. Therefore a single forecast is no longer the answer to the problem. The modelling of different long-term electrical forecasts makes it possible to compare a number of different forecasts. The modelling provides the further option that each expected load can be entered as a range and then the developed balancing algorithm checks for consensus (feasibility). If feasibility exists, then the different forecasts are reconciled (a feasible solution is determined). Factors such as international and national market trends, economical cycles, different weather patterns, climate cycles and demographic changes are studied. The factors that have significant impact on the transmission electrical loads are integrated in ten different forecasts. It thus gives more insight into the electrical industry and makes the forecast results more informative and therefore reduces the uncertainty in the future expected loads.

Orientador: Sinclair Mallet-Guy Guerra / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-23T20:32:36Z (GMT). No. of bitstreams: 1 OliveiraJunior_AntomarViegasdeCarvalhoe_M.pdf: 10159272 bytes, checksum: 55aaa1b3047a2f48a89d4c3bdf4e7668 (MD5) Previous issue date: 1998 / Resumo: A atuação efetiva sobre a arborização urbana constitui importante elemento para a imagem e eficiência empresarial das companhias de distribuição de energia, não só pelos índices expressos na atualidade, mas principalmente pela sua significativa taxa de crescimento. Por sua vez, as atividades de poda, isoladamente, além de constituírem-se em gastos periódicos e que não guardam qualquer relação com investimentos para melhoria de redes, não possibilitam o completo equacionamento da questão. Além disso, acarretam desgastes com Prefeituras e comunidades e tem sido pautadas pela ausência de técnicas adequadas, potencializando o problema. O presente trabalho pretende determinar a importância dos efeitos provocados pelo contato da arborização sobre a rede elétrica e estabelecer alternativas visando melhorar a performance do sistema elétrico de distribuição e proporcionar uma arborização urbana harmoniosa de forma a reduzir-se sensivelmente à necessidade de podas e, naquelas onde esta atividade seja indispensável, executá-Ias de forma tecnicamente correta, garantindo o equilíbrio, saúde e estética das espécies vegetais / Abstract: The effective performance on the urban tree planting issue is a important element for the energy distribution company's image and efficiency, not only because of the indices presently shown, but also mainly of their significant increase rate. Besides presenting periodic expenses and not having any relation with investments to improve networks, the sole pruning activities do not provide the total solution to the matter. Moreover, such activities cause problems to the City Governments and communities and are mentioned due to the lack of proper techniques making the problem worse. This work intends, therefore, to determine the importance of effects caused by the contact of vegetation with the power system and to stablish alternative to trying provide a harmonious urban tree planting, so as to greatly reduce the needs of pruning, and where such an activity is indispensable to find ways to do it in a technically correct way, assuring the balance, health and aesthetic of the vegetation species / Mestrado / Energia, Sociedade e Meio Ambiente / Mestre em Planejamento de Sistemas Energéticos

Orientador: Antonio Padilha Feltrin / Coorientador: Carlos Roberto Minussi / Banca: Jose Roberto Sanches Mantovani / Banca: André Nunes de Souza / Resumo: As perdas de energia elétrica por fraudes, ligações clandestinas ou erro na medição são denominadas Perdas Não-Técnicas ou Perdas Comerciais e seu combate tem sido prioridade quer por empresas concessionárias de distribuição de energia elétrica, quer por órgãos reguladores. Nesse contexto, neste trabalho, implementa-se computacionalmente um sistema inteligente híbrido intercomunicativo específico que se baseia no emprego de diferentes técnicas oriundas da área de sistemas inteligentes tais como redes neurais e lógica fuzzy em módulos independentes e que se comunicam entre si. O sistema é baseado em três pilares: extração automática de conhecimento a partir da base de dados da concessionária, incorporação na metodologia do conhecimento e experiência de especialistas e, em último, consultas na base de dados por características específicas de cada cliente. A metodologia utiliza simultaneamete inúmeros dados reais de entrada de natureza diversa e combina várias técnicas a fim de verificar o risco percentual de cada cliente de possuir alguma anomalia que implique em perda comercial. Além dos dados cadastrais e do histórico de consumo mensal dos clientes, comumente utilizados pelos trabalhos orientados à detecção de perdas comerciais, a metodologia proposta utilizou também dados adicionais tais como a lista de nomes e de atividades suspeitas. A utilização de dados adicionais possibilitou uma melhoria na detecção de clientes anômalos, grande parte dos quais seriam possivelmente considerados normais pelos trabalhos da literatura avaliada. Neste trabalho, pretende-se detectar as perdas comerciais de maneira mais rápida e precisa possível. Investigações adicionais devem ser feitas posteriormente para encontrar quais são as causas que culminaram em altas perdas comerciais em... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Electrical energy losses due to theft, fraud or error in the measurement are called Non-Technical Losses and their reduction has been a priority utilities power and by regulators. In this context, this paper presents the computational implementation of an intelligent hybrid system that combines techniques such as neural networks and fuzzy logic. The system is based on three pillars: knowledge extraction from the database utility, incorporating the methodology of knowledge and experience of experts and queries the database for specific features of each client. The methodology uses several simultaneous input of diverse nature and combines several techniques to verify the percentage risk of each customer to have some problem to configure non-technical losses as fraud, defective in the measurement system. In this paper, the main objective is to locate the focus of the problem more quickly. Further investigations should be made later to find what are the causes that resulted in high nontechnical losses in a feeder or in a specific region. This work covers the registered customers at utilities power, especially residential... (Complete abstract click electronic access below) / Mestre

Orientador: José Roberto Sanches Mantovani / Co-orientador: Antonio Marcos Cossi / Co-orientador: Javier Contreras Sanz / Banca: Ruben Agusto Romero Lazaro / Banca: Marcos Julio Rider Flores / Banca: Benemar Alencar de Souza / Banca: Geraldo Roberto Martins da Costa / Resumo: O problema do planejamento de sistemas de distribuição de energia elétrica consiste em determinar as condições topológicas, estruturais e físicas necessárias para que o sistema seja capaz de operar, nos cenários de demanda atual e futuros, segundo os critérios técnicos exigidos pelas agências reguladoras. Visando atender tais condições de operação, algumas ações podem ser realizadas no sistema as quais dividem-se em ações de médio e longo prazo. As ações de médio prazo são aquelas realizadas sem que haja a expansão do sistema, e neste trabalho são consideradas como tais: a alocação de banco de capacitores, reguladores de tensão e recondutoramento de linhas. Por outro lado, as ações de longo prazo possuem custos mais elevados, pois visam à expansão do sistema considerando os futuros cenários de operação. Neste trabalho, além das tradicionais ações adotadas para a expansão do sistema de distribuição, considera-se também a alocação de geração distribuída a fim de avaliar os seus impactos sobre a expansão do sistema. Os modelos matemáticos propostos para os problemas de planejamento de médio e longo prazo são multiobjetivo e resolvidos através das metaheurísticas algoritmo genético multiobjetivo e busca tabu multiobjetivo, respectivamente. No modelo de médio prazo, os objetivos tratados são a regulação de tensão e os custos de investimento e operação. São utilizadas técnicas de redução do espaço de busca baseadas em lógica fuzzy, para melhorar o desempenho do algoritmo genético proposto. Para o modelo de longo prazo, os objetivos são os custos de investimento e operação considerando as opções de compra de energia (gerador distribuído e subestações) e a confiabilidade da rede planejada, através dos custos de energia não suprida. No modelo de longo prazo considera-se a existência de vários estágios dentro do horizonte de planejamento, ... / Abstract: The electric power distribution systems planning problem consists of determining the topological, structural and physical conditions necessary for the system to be able to operate, in the current and future scenarios of demand, according to the technical criteria required by regulatory agencies. Aiming to meet these operating conditions, some actions can be performed on the system, they can be divided into short and long term actions. Short-term actions are the ones performed without the system expansion. In this work the following actions are is treated as such short-term actions: the capacitor banks and voltage regulators allocation and the change of cables in the system. On the other hand, the long-term actions have higher investment costs, because they aim to expand the system, considering the future operation scenarios. In this work, in addition to the traditional actions taken to expand the distribution system, we also consider the allocation of distributed generation, in order to assess its impacts on system expansion. The mathematical models proposed for short and long term planning problem are multiobjective and solved by the metaheuristics multiobjective genetic algorithm and multiobjective tabu search, respectively. In the short-term model the goals addressed are: voltage regulation and the investment and operation cost. Techniques for search space reducing based on fuzzy logic are used to improve the performance of the proposed genetic algorithm. In the long-term model the goals are: the investment and operation costs, entertaining the options of power purchase (distributed generator and substations) and the reliability of the planned network, through the costs of energy not supplied. In the long-term model, we take into account the existence of various stages within the planning horizon, making the model multi-stage, which is solved by utilizing the dynamic planning model. The integration ... / Doutor

Orientador: Marcos Julio Rider Flores / Banca: Ruben Augusto Romero Lazaro / Banca: Antônio César Baleeiro Alves / Resumo: Este trabalho apresenta o desenvolvimento de um modelo de programação cônica de segunda ordem inteira mista para resolver o problema de reconfiguração de sistemas de distribuição de energia elétrica radiais. A intenção desta pesquisa é propor uma nova metodologia que seja eficiente para resolver o problema de reconfiguração de sistema de distribuição que geralmente é modelado por um problema de programação não linear inteiro misto. Foi provado que o ponto de operação em regime permanente de sistemas de distribuição radial pode ser modelado matematicamente como um problema de programação cônica de segunda ordem. Este modelo matemático foi estendido para resolver o problema de reconfiguração de sistema de distribuição. O uso de um modelo de programação cônica de segunda ordem inteira mista garante a convergência para a solução ótima usando as ferramentas de otimização clássica existentes. Os sistemas testes de 33, 70, 136 e 417 nós são utilizados para evidenciar a precisão do modelo matemático proposto, como também a eficiência destas técnicas de soluções para o problema de reconfiguração de sistemas de distribuição de energia elétrica radiais / Abstract: This paper presents the development of a model of mixed integer second-order cone programming to solve the problem of reconfiguration systems power distribution radial. The intent of this research is to propose a new methodology that is efficient to solve the reconfiguration problem of distribution system which is usually modeled as a problem of mixed integer nonlinear programming. It was proven that the operating point in steady radial distribution systems can be modeled mathematically as a problem of second-order cone programming. This mathematical model has been extended to solve the problem of reconfiguration of distribution system. The use of a model mixed integer second-order cone programming ensures convergence to the optimal solution using the existing classical optimization tools. Systems tests 33, 70, 86, 136 and 417 nodes are used to assess the accuracy of the mathematical model, but also the efficiency of these technical solutions to the problem of reconfiguration of distribution systems of electric power radial / Mestre