Avaliação da representação tensorial da potência instantânea em condições senoidais equilibradas

Monografia (graduação)—Universidade de Brasília, Faculdade UnB Gama, Curso de Engenharia de Energia, 2014.Este trabalho se propôs a estudar o comportamento da potência elétrica instantânea em condições senoidais equilibradas por meio da definição do tensor potência instantânea. Esse tensor é definido para que seja possível aplicar uma analogia entre os estudos da mecânica dos meios contínuos para deformação e os estudos das potências ativa e reativa de um sistema elétrico trifásico. Procura-se relacionar o tensor potência elétrica e suas componentes simétrica e antissimétrica com as definições das parcelas de potência ativa e reativa da potência instantânea. A proposta principal do documento é analisar as alterações na forma da representação espacial do tensor potência instantânea assim como é feito na representação do elemento de volume cúbico do tensor de deformações. Dessa forma, fundamenta-se uma interpretação geométrica que associa qual componente da potência altera o volume total e qual a componente da potência que provoca alterações rotacionais da representação espacial do tensor potência elétrica instantânea. ____________________________________________________________________________ ABSTRACTThis work aimed to study the behavior of instantaneous electrical power in balanced sinusoidal conditions by defining the instantaneous power tensor. This tensor is defined so that it is possible to apply an analogy between the study of continuum mechanics for deformation and the study of active and reactive power in a three phase electrical system. It seeks to relate the tensor electric power and its symmetric and antisymmetric components with the definitions of the parcel of active and reactive power of instantaneous power. The main purpose of the document is to analyze the changes in the form of spatial representation of the instantaneous power tensor as it has done in the representation of the cubic volume element of the strain tensor. Thus, is based on a geometric interpretation that associated what power component alters the total volume and what power component causes rotational changes of the spatial representation of the instantaneous power tensor

Método generalizado de localização de faltas baseado na teoria de ondas viajantes para linhas de transmissão não-homogêneas

Tese (Doutorado em Engenharia Elétrica)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, Brasília, 2020.Um algoritmo generalizado de dois terminais baseado na teoria de ondas viajantes para linhas não-homogêneas de múltiplas seções é proposto nesse documento de tese de doutorado. O algoritmo é capaz de identificar a seção da linha com falta e, na sequência calcular de forma precisa a distância da falta. Para desenvolver essa solução, uma formulação matemática generalizada é primeiramente proposta para identificar o trecho com falta, requerendo ajustes simples. Para tanto, necessita-se da detecção das primeiras frentes de onda incidentes nos dois terminais da linha monitorada, tal como realizado por métodos tradicionais. Por fim, uma vez detectado o trecho da linha com falta, uma formulação fechada baseada em ondas viajantes é proposta para estimar a distância de falta em relação a um dado terminal de referência. Uma vez que são utilizados como entrada parâmetros da linha monitorada, propõe-se também uma versão do algoritmo capaz de acomodar possíveis imprecisões nos parâmetros da linha a fim de torná-lo mais conservador. Um algoritmo baseado na transformada wavelet é utilizado na solução desenvolvida, garantindo a correta identificação das frentes de onda de interesse em casos de transitórios atenuados combinados com ruídos do sistema elétrico. A avaliação do método proposto foi realizada por meio de simulações digitais de faltas através do Alternative Transients Program (ATP), nas quais foi considerada uma linha não-homogênea, composta por trechos aéreos, subterrâneos e submarinos, usando parâmetros provenientes de sistemas elétricos reais. Os resultados obtidos comprovam a eficiência do método proposto em identificar corretamente o trecho com falta e localizar com precisão os pontos de faltas mesmo em situações de transitórios atenuados, na presença de ruídos eletromagnéticos no sistema e imprecisões nos parâmetros elétricos da linha.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).A generalized two-terminal traveling wave-based fault location algorithm for non homogeneous lines with multiple sections is proposed in this PhD thesis document. The algorithm is able to identify the faulted section and, then, to accurately calculate the fault distance. In order to develop such a solution, a generalized mathematical formulation is firstly proposed to identify the faulted section, requiring simple settings. To do so, only the detection of the first incident wavefronts at both line terminals is needed, as traditional methods do. Finally, once the faulted section is identified, a closed-form traveling wave-based fault location formulation is proposed to estimate the fault distance from a given reference terminal. It is also proposed a version of the algorithm capable of accommodating possible inaccuracies in the parameters of the line in order to make it more conservative in real applications. A wavelet-based sensitive transient detection algorithm is used in the developed solution, guaranteeing the proper identification of the wavefronts of interest in cases of attenuated transients combined to power system noise. The evaluation of the proposed method was carried out by means of digital fault simulations in the Alternative Transients Program (ATP), through which a non-homogeneous line composed by overhead, underground and submarine sectoins was modeled, using parameters taken from real electrical systems. The results show the efficiency of the proposed method, attesting it is able to correctly identify the line faulted section and to precisely pinpoint the fault either in cases of attenuated transients and in the presence of noise and inaccuracies in the line electrical parameters

Fuzzy Inference System for fault detection in internal combustion engines in Thermoelectric Power Generating Plants

In this work, an approach to implement a simplified fuzzy inference model for monitoring the conditions of workings of power generators through the pressure values ​​of combustion temperature and engine water pressure is displayed. The model helps the supervisory system, through real-time evaluation of the operating conditions of the engine in percentage rates. The application of tools based on computational intelligence, have shown efficiency in various areas of industrial engineering

Evaluation of Physic-chemical Parameters of Water Quality on Agricultural Fields of Western Bahia

For the diagnosis of the quality of water it is necessary to execute a set of analyzes (physical and chemical) of the body of water that will provide information that integrate biotic and abiotic factors that govern the functioning of the ecosystem. The objective of this study is to evaluate the quality of water from wells and rivers of Urucuia aquifer region for investigation of contamination or contamination risks. Were realize collections in nine (9) areas of western Bahia, which were collect in each area, two points of well water samples and a river, and determining the electrical conductivity, pH, dissolved ions and metals. The results were compare with the maximum permissible values (MPV) for human consumption by Ordinance No. 2914/11 of the Ministry of Health and National Environment Counsel - CONAMA (Resolution 357 and supplementary resolutions). The quantitative results of the analysis showed that the surface and well waters that are part of the aquifer Urucuia within the parameters investigated are below the values recommended by the legislation showing that the agricultural activities in the region has not affected to the evaluated parameters, the quality of water for human consumption. However, it is necessary a monitoring of surface and groundwater in the region with expansion parameters evaluated. DOI: http://dx.doi.org/10.17807/orbital.v9i2.88

Approach of Passive Filters using NSGA II in industrial installations: Part I

The optimization of passive filters in industrial systems has been presented by different computational methods. The objective of this paper is to develop a computational algorithm with NSGA II to select the configuration and design parameters of a set of passive filters for industrial installations. As a methodology, the optimization problem was addressed using three independent objective functions of innovative character for compensation of harmonics through passive filters as a multiobjective problem. The results were the computational solution to this problem that determines a set of Pareto optimal solutions (Frontier). In addition, the computational tool has several new features such as: calculates the parameters that characterize the filters, but also selects the type of configuration and the number of branches of the filter in each candidate bar according to a set of pre-established configurations according to PRODIST-M8 (Brazilian Standard) and IEEE 519-2014. Also determine solutions with good power quality indicators (THD, TDD and NPV) for several characteristic and non-characteristic scenarios of the system that allow to represent: daily variations of the load, and variations of system parameters and filters. It evaluates the cost of energy bills in an industrial power grid that has different operating conditions (characteristic scenarios) and evaluates the economic effect of harmonic filters as reactive power compensators

Educational approach for fault detection in Internal Combustion Engines with Matlab Toolbox Fuzzy Logic

Fuzzy logic is the logic defined from the theory of fuzzy sets. It differs from the crisp logic (traditional) in their characteristics and their details. In textbooks on fuzzy inference systems, exemplified superficially implementation creating doubts among computer science students. Traditionally, teachers teach IC with the use of conceptual models. This model was to serve specified parameters computing courses, allowing students to study and development of computational models using Matlab Fuzzy Logic Toolbox (MFLT) for fault detection in engines. This paper proposes an academic learning model based on fuzzy inference and modeling to detect incipient faults in components of internal combustion engines

Efficacy and safety of subconjunctival bevacizumab for recurrent pterygium

Purpose: To evaluate the clinical outcome(s) and complication(s) of subconjunctival bevacizumab treatment in patients with recurrent pterygium. Methods: This prospective case series included patients who had undergone pterygium surgery and were diagnosed with recurrent pterygium. All patients received one subconjunctival injection of 0.5 mL of bevacizumab (2.5 mg/0.1 mL). The main outcome was the change in size and clinical appearance. The clinical appearance of the pterygium was graded according to Tan and colleagues. The horizontal size of the pterygium (from limbus to apex) was recorded from baseline to 2 months after injection. Treatment-related complications and adverse events were reported. Results: We included 36 eyes of 36 patients (18 males) with a mean age of 58.75 ± 10.98 years. Totally, 30.6% patients developed recurrent pterygium in both eyes (only the worst eye was treated), with 47.2% developing it in the left eye and 22.2% in the right eye. More than half the patients (58.3%) had a family history of pterygium. There was a significant difference in the size of pterygium at different intervals (P<0.05). Approximately two-thirds (66.7%) of patients presented with hyposphagma on the 2nd day after subconjunctival application; this value decreased to 30.6% by day 7 and to 0% at 1 month. Most patients (69.4%) exhibited amelioration of irritative symptoms within 2 days, 88.9% after 7 days, and 97.2% after 1 month. Conclusions: Subconjunctival bevacizumab injection is useful for the management of patients with recurrent pterygium, with no significant local or systemic adverse effects