Programa de Pós-Graduação em Engenharia Elétrica - PPGEE/ITEC

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2314

O Programa de Pós-Graduação em Engenharia Elétrica (PPGEE) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA) foi o primeiro e é considerado o melhor programa de pós-graduação em Engenharia Elétrica da Região Amazônica. As atividades acadêmicas regulares dos cursos de mestrado e doutorado são desenvolvidas principalmente nas Faculdades de Engenharia Elétrica e Engenharia de Computação, supervisionadas pela Coordenação do Programa de Pós-Graduação em Engenharia Elétrica (CPPGEE).

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Agora exibindo 1 - 20 de 28

Acesso aberto (Open Access)
Análise de modelos, simulações e ensaios de impulso em um transformador de distribuição.
(Universidade Federal do Pará, 2019-03-12) CARDOSO, Antonio Fernando Martins; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
Acesso aberto (Open Access)
Análise de supraharmônicos em equipamentos eletrônicos e caracterização utilizando a transformada wavelet
(Universidade Federal do Pará, 2018-09-10) RODRIGUES, Carlos Eduardo Moreira; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
Esta dissertação objetiva analisar a emissão, a propagação e a interação entre equipamentos envolvendo componentes harmônicas que possuem frequência na faixa entre 2 kHz e 150 kHz, denominadas supraharmônicos. A literatura especializada já reportou a emissão de supraharmônicos por equipamentos eletrônicos como lâmpadas fluorescentes, lâmpadas LED, inversores de frequência e nobreaks, além de impactos relacionados ao aquecimento de cabos e terminações, ruído acústico e interferência em sistemas PLC (Power Line Communication). No presente trabalho, foram realizadas campanhas de medição, em ambiente laboratorial, em inversores de frequência e um conjunto de lâmpadas LED. As medições se dividiram em dois grupos distintos: com os equipamentos conectados à rede elétrica e a uma fonte eletrônica trifásica, com o objetivo de verificar as ordens e os níveis, tanto das emissões provenientes dos equipamentos, quanto da distorção emitida pela própria fonte eletrônica, além da interação entre a fonte e os equipamentos alimentados. Foram empregadas a Transformada de Fourier e a Transformada Wavelet Packet para efetuar a análise e caracterização das distorções observadas. As medições mostraram uma contribuição significativa dos equipamentos observados e da fonte eletrônica para a emissão de supraharmônicos, além da amplificação da distorção quando os equipamentos são por ela alimentados.
Acesso aberto (Open Access)
Análise do impacto de geradores fotovoltaicos na estabilidade transitória de geradores síncronos distribuídos
(Universidade Federal do Pará, 2018-02-19) PINHEIRO, Wanessa Tâmiris de Souza; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
This dissertation aims to present a comparative analysis between two models of inverter control for the study of the transient stability analysis and voltage stability, with the insertion of the photovoltaic generation in the distribution electric grid. It is also proposed an analysis of the influence, both negative and positive, caused by the control modes of these inverters in the stability of synchronous machine connected to the grid. Another proposed solution to be investigated in this work will be the use of the reactive power control mode of photovoltaic generators via the inverter, which can contribute to the relief of the reactive demand of distributed synchronous generators interconnected in the same electric system, in order to reduce the possibility of generating a voltage instability condition, after a big disturbance, or in the occurrence of contingencies in the electric power system that may affect weak or overloaded electrical grids and with large insertion of photovoltaic generators. The analysis of the control models will be carried out through simulations in the time domain, through the ANATEM and ANAREDE computational tools.
Acesso aberto (Open Access)
Análise dos impactos harmônicos na qualidade da energia elétrica utilizando kdd – estudo de caso na Universidade Federal do Pará
(Universidade Federal do Pará, 2019-03-18) SILVA, Waterloo Ferreira da; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
The present work presents an analysis of data related to Power Quality (PQ), the increasing use of nonlinear loads, equipment based on power electronics in residential, commercial and industrial installations are contributing to the significant increase in the levels of harmonic distortion of current and, consequently, of voltage, as observed in the Brazilian electricity distribution system. It was developed in Brazil, the distribution procedures in the national electricity system (PRODIST), created and developed by the National Electric Energy Agency (ANEEL). PRODIST aims to standardize and standardize activities related to energy distribution, including product quality standards. In order to monitor the quality of the product "electric energy" through the harmonic content generated by the electric network of the institution, a methodology is proposed for the analysis using computational intelligence (CI) and data mining techniques to analyze the data collected by meters of energy quality installed in the main sectors of this institution and at the point of common coupling of the consumer and consequently establish the relationship between the harmonic currents of the nonlinear loads with the harmonic distortion at the common coupling point. The KDD process was applied, including the collection, selection, cleaning, integration, transformation and reduction, mining, interpretation and evaluation of the data, in order to monitor the quality of the product "electric energy" through the harmonic content generated by the electric grid. educational institution. In the "Data Mining" data mining phase, the Naive Bayes classifier was used. The obtained results showed that the KDD process has applicability in the analysis of the Total Harmonic Distortion of Voltage at the Common Coupling Point and can be applied in any commercial, residential and industrial area.
Acesso aberto (Open Access)
Análises multifísica via método de elementos finitos para o auxílio à manutenção preditiva em transformadores de potência.
(Universidade Federal do Pará, 2018-09-21) SOUSA, Antonio Roniel Marques de; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
The National Interconnected System (NIS) is an organ of fundamental importance in the Brazilian panorama. Its function is to electrically connect generating centers and consumer centers, whether they are business, commercial or residential. The main equipment responsible for the connection and transmission of electric power from the generating centers to the consumers are the power transformers. This equipment is subject to several types of faults that can affect its components, in some cases compromising the operation of this equipment, and consequently the supply of electric energy. In this work, a multiphysical analysis is performed on power transformers, coupling thermal and structural electromagnetic simulations with the objective of providing the operator with information about the ideal moment for performing predictive maintenance, avoiding unplanned shutdowns. For this, computational simulations using the Finite Element Method (FEM) were used and from this, we analyzed the different situations that these equipments can be submitted, in the nominal condition, as well as extreme conditions of operation like current of inrush and current short-circuit. In this perspective, analyzes of the effects that the thermal expansion and the axial forces and radia exerted contributing to possible defects in these equipments were carried out. As a study object, the simulations were performed in a 50 MVA single-phase transformer, which is an equipment that is in operation in the northern region of the country. For a more validation of the methodology used in this work the simulations were validated with real measurement data and with results present in current literature. In this way, this work presents a methodology that can help the technical framework of an industry in the decision of the appropriate moment of stop in a power transformer for the accomplishment of predictive maintenance.
Acesso aberto (Open Access)
Augmentação estocástica com horizonte de predição estendido baseada no PID para um sistema multivariável
(Universidade Federal do Pará, 2019-10-25) CRUZ, Jahyrahã Leal dos Santos; SILVEIRA, Antonio da Silva; http://lattes.cnpq.br/1828468407562753
The objective of this research was to investigate and design a control system based on the Stochastic Augmentation with Extended Prediction Horizon using 10-steps ahead, consisting of the union of characteristics of a linear deterministic controller with a stochastic predictive controller, resulting in a control system with guaranteed robustness and with predictive, linear, and stochastic characteristics. For the application of the Stochastic Augmentation, the chosen controllers were the classic PID and the GMV in its incremental form, where the former was augmented resulting in a controller with extended prediction horizon, the AEHP. The classic PID controller in the discrete time domain is compared to AEHP. Both controllers were tested in simulations with a process model that represents the dynamics of a helicopter, denominated 2DOF Helicopter (H2DOF), produced by the Quanser company. The H2DOF is a multivariable system, whose model in the state space is transformed to the transfer function form, generating two coupled subsystems, one for the pitch angle and other to the yaw angle, in which the couplings influence were considered as disturbances in the controllers design stage. The transformation of the system model to the transfer function form reduced the complexity of multivariable system in the state space, allowing the use of a more simple control law. Furthermore, it was performed the pairing of input and output, to verify what output was more sensible the one specific input, by means of Relative Gain Array. And to prove the control system efficiency based in the Stochastic Augmentation with extended prediction horizon, simulations were realized using the software Matlab®, assessing the performance of extended prediction horizon, enduring the coupled dynamics, facing load disturbances and Gaussian disturbances. The essays were evaluated by robustness and performance indices. The predictive AEHP controller obtained better results for most indices with guaranteed robustness, compared to the discrete-time PID controller.
Acesso aberto (Open Access)
Avaliação do desempenho das funções de controle volt-watt e volt-var em inversores fotovoltaicos integrados nas redes de distribuição
(Universidade Federal do Pará, 2018-03-27) WANZELER, Tiago Machado; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
This dissertation addresses some of the major operational problems faced by distribution system operators due to the high integration of photovoltaic (PV) generators, such as overvoltages and excessive tap counts in step voltage regulators (SVR). These situations are continually being studied, since they can cause voltage quality problems and damage in SVRs. The overvoltage problem can be caused by a significant injection of active power from the PV generation to the network. Moreover, the rapid and significant variations in PV generator active power associated with cloud transients result in an increase of voltage regulator tap counts, which can affect the useful life of device. In this context, the smart inverters Volt-Watt and Volt-Var control functions have been added in recent studies to mitigate the overvoltages. This work shows how Volt-Watt and Volt-Var control functions mitigate the overvoltage and voltage regulation problems in distribution networks with PV generation. Time series power flow simulations on LV and MV single feeders with PV solar plant have been performed in high and low solar variability scenarios.
Acesso aberto (Open Access)
Avaliação operacional dos efeitos do perfil de demanda de quatro sistemas de microgeração fotovoltaica conectados à rede
(Universidade Federal do Pará, 2018-06-29) PARIJÓS JÚNIOR, Ivan Ruy de; PEREIRA, Edinaldo José da Silva; http://lattes.cnpq.br/9596575345034065; MACÊDO, Wilson Negrão; http://lattes.cnpq.br/3386249951714088
Power quality has been widely researched. Several phenomena that affect power quality, and its consequences, have been investigated. When the power quality theme involves the operation of a grid-connected photovoltaic system, the main concern is about the operation of the inverter, which is responsible for the interface of the photovoltaic generator with the grid. The introduction of photovoltaic generation in the grid requires attention on certain factors such as changes in the load curve, voltage level, harmonic components in the inverter current and variation on the power factor (PF) of the costumer. This work aims to test and evaluate some aspects that may influence the power quality due to the insertion of photovoltaic generation in the grid, associated whit the load demand. Four grid-connected photovoltaic systems were used to develop this work, as well as a data acquisition bench that was set up to monitor the operation of these systems. In this work it is possible to conclude that the operation of photovoltaic systems causes changes in the voltage level at the point of common coupling. Also, the interaction between photovoltaic systems and loads causes changes in the load profile measured by the side of the grid, causing the total harmonic distortion in the current (THDi) and PF measured at this side to be different from those measured at the loads and photovoltaic sides. It is possible to observe that the grid-connected photovoltaic system can contribute to increase or reduce the THDi seen by the local grid, where the greatest contribution of harmonic distortion in the current delivered by the grid is associated to the demand profile of the load.
Acesso aberto (Open Access)
Cálculo de perdas técnicas e não técnicas nas redes de distribuição de energia elétrica usando a definição de impedância equivalente de perdas
(Universidade Federal do Pará, 2018-10-17) PAYE, Juan Carlos Huaquisaca; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
This work presents a new concept called Loss Equivalent Impedance (LEI), which is characterized by being a practical and economical method that allows calculating technical and non-technical losses in electricity distribution networks with good accuracy, for which it uses the data that any electric utility has, such as the user's electricity bills, the grid's electrical parameters and the measurements of power and currents at the substation coupling point. To show the application of this method, this document covers the data processing and description of the software used to simulate the operation in the test systems IEEE 13 and 37 buses networks, considering that they present technical and non-technical losses. In addition, these systems are evaluated with different operational conditions, including the incorporation of a photovoltaic plant. The cases evaluated in this work show that the method can be used to plan and monitor the electricity distribution networks, considering the separation of technical and non-technical losses, so that in future reduction actions concerning these losses can be managed, since of unmanaged electricity losses is translated into considerable economic losses for both the utility and customers and indirectly for the country. The results presented in this dissertation, regarding the application of the Equivalent Operational Impedance to the calculation of technical and non-technical losses, have demonstrated the effectiveness of the proposed methodology, so that it is foreseen a great potential for the application of the proposed procedure in the electrical sector mainly in the distribution utilities.
Acesso aberto (Open Access)
Comparação entre regressão linear, redes neurais artificiais e árvores de regressão para quantificação do impacto harmônico de múltiplas cargas em redes elétricas de distribuição.
(Universidade Federal do Pará, 2018-11-19) PAIXÃO JÚNIOR, Ulisses Carvalho; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
In recent years, the socio-economic development of the population, the growth of commercial and industrial sectors, as well as the ever-increasing installation of new electrical loads, have generated great evolution in demand of electricity consumption. In turn, to obtain more efficient systems, the manufacturers have produced equipment more energy efficient for residential, commercial and industrial use. However, these loads due their non-linearities, have contributed significantly to the increase in harmonic distortion levels of voltage and current, raising the concern of the power sector managers with respect to the power quality, mainly, due to the difficulty in the identification of the origin of the harmonic distortion. Therefore, to anticipate the harmonic effects and meet the current legislation, through computational techniques, this work emphasis is placed on the common coupling point (CCP) of consumers and utility, regardless of consumption characteristics and loads, to assess the harmonic impacts in his grid, besides comparing the reliability level of the techniques through the mean absolute error (MAE). The proposed methodology uses the Electrical Power Quality System (SISQEE) software that allows the use of three different computational techniques, such as Linear Regression, Artificial Neural Networks and Regression Trees, to evaluate the harmonic contribution of each feeder at the point of interest of the chosen electric grid. To prove the validity of the methodology, two case studies, based on real measurements at a university and at an industrial district, was carried out with a minimum sampling period of seven days using power quality analyzers, according to the distribution procedures by ANEEL (PRODIST). As a result of the power quality, it was verified how much each feeder impacts the voltage and current distortion at the CCP, besides classifying the feeders in relation to their respective impacts in the studied electrical grid. Also, as a result, the studies allowed the evaluation of performance between the different techniques, with different time intervals (weekly, daily and per load level), allowing to classify the behavior and reliability of each technique in each period. As a conclusion of the work, the proposed methods and analyzes presented allow managers to perform a more efficient mitigation action of the harmonic impacts caused in the electrical network and, also, to identify the differences between the techniques and their degree of reliability, in accordance with the time intervals studied.
Acesso aberto (Open Access)
Desenvolvimento e modelagem de uma nanorrede de distribuição em corrente contínua em baixa tensão com sistemas de geração distribuída
(Universidade Federal do Pará, 2019-10-23) TORRES, Pedro Ferreira; MACÊDO, Wilson Negrão; http://lattes.cnpq.br/3386249951714088
The concept of direct current distribution minigrids has been gaining ground in academia and industry regarding the development of distribution grid applications with high penetration of distributed energy sources and storage systems. The adoption of a direct current distribution system facilitates the integration of sources such as photovoltaic and wind generation and storage systems such as batteries, as these technologies in general operate intrinsically in direct current. This work presents the development of a direct current distribution nanogrid (DCDN) installed in the laboratory of the Grupo de Estudos e Desenvolvimento de Alternativas Energéticas (GEDAE), of the Universidade Federal do Pará. The developed grid is composed of three photovoltaic generation and storage systems in battery banks and three load banks, distributed over the 200 m grid in a ring topology, with a 24 Vdc bus. Two simulation methodologies were developed and are capable of reproducing the nanogrid’s operational behavior under static and dynamic conditions, allowing the evaluation of the grid performance over a day of operation. Tests are also presented with measurements at strategic points of the grid to evaluate the system behavior under specific operating conditions, being normal or under contingency. The results attest the nanogrid's ability to reliably supply the loads, as long as it respects the limitations of the implemented power generation and storage capacities. In addition, it was found that the characteristics related to the topology of the commercial charge controller that is used to form the DC distribution nanogrid benefits the power quality for the developed grid size and topology.
Acesso aberto (Open Access)
Estimativa da capacidade de hospedagem de geração distribuída em redes de distribuíção via algoritmos genéticos
(Universidade Federal do Pará, 2019-03-29) SOUSA, Alana Lima de; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
The use of distributed generation (DG) and distributed energy sources (DER) close to the consumer centers has been gaining prominence around the world. The high penetration level of DG will shift the operation paradigm of electric energy systems, affecting power quality delivered to consumers. The active power injection from DG can cause several consequences to distribution systems, being overvoltage issue the most impacting of them. The reverse power flow from the DG units can cause voltage rise issue on distribution networks and consequently the DG shutdown. During unity power factor (pf) operation of DG, the distribution operators control overvoltage by active power curtailment. In this scenario emerges the GD hosting capacity concept, which consists of estimating the maximum power injected by GD without compromising voltage quality of the distribution system. This dissertation estimates the DG hosting capacity on MV distribution systems using genetic algorithms, considering as main limiting factor the overvoltage issue. Performance tests were performed on IEEE 33-bus and IEEE 69-bus systems.
Acesso aberto (Open Access)
Formulação analítica para estudo de redes de distribuição ativas considerando a presença de reguladores de tensão
(Universidade Federal do Pará, 2019-09-26) BRITO, Hugo Rodrigues de; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
Step voltage regulators (SVRs) located at medium-voltage radial feeders are often part of many strategies to mitigate interconnection impacts of distributed generation (DG) units. However, conventional methods for rapid analysis of characteristic parameters of active distribution networks do not usually factor the effect of SVR tap operations in their calculations. This dissertation proposes a novel analytical formulation for the assessment of the influence of such devices, based on mathematical modification of traditional expressions found in the literature. The developed theoretical framework concerns voltage variation along the feeder, requirement of reactive power, electrical losses and DG hosting capacity. The proposed approach is validated via comparative studies conducted in a simple test-system, as well as in a long 34.5 kV rural feeder that contains two cascaded SVRs along with a high penetration DG at its far end. The Open Distribution Simulator Software (OpenDSS) is used for modelling, traditional load flow simulations and quasi-static time series analyses. Results show the merits of the developed formulation in correctly estimating active distribution networks’ parameters in the presence of SVRs, which marks an improvement over conventional tools for DG integration preliminary studies.
Acesso aberto (Open Access)
Gerenciamento ótimo de um sistema de armazenamento de energia utilizando recozimento simulado
(Universidade Federal do Pará, 2018-01-18) ANGELIM, Jorge Henrique Costa; AFFONSO, Carolina de Mattos; http://lattes.cnpq.br/2228901515752720
This work proposes a method of energy management of a university campus, with a photovoltaic solar generation source and a energy storage system, which are connected to the main grid. The developed method aims to minimize the purchase of energy from the external grid using the Simulated Annealing optimization method. It is considered in the simulations variable energy tariffs according to the period of the day applied by the local utility. The obtained results were satisfactory, since the applied management scheme managed to reduce energy consumption significantly throughout the day, taking advantage of the energy stored at cheaper tariff schedules and greater availability of solar generation at peak times, making a minimum daily cost while it reaches the constraints associated with the problem. The obtained results showed the applicability of the optimization method, through the determination of operating points of the battery bank that maximized the use of available resources
Acesso aberto (Open Access)
Grau de confiabilidade operacional de transformadores de instrumentos para sistemas de energia elétrica
(Universidade Federal do Pará, 2018-06-21) SOUSA, Eleanor Dias de; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
Instrument transformers (ITs) such as current transformers (CTs), potential transformers (PTs) and capacitive potential transformers (CPTs) are fundamental equipment in systems involving protection, command, control, supervision and measurement related to the Electric Power System – EPS. The purpose of evaluating the reliability of substation equipment, in particular CTs and PTs, and the impact caused to the Transmission Functions (TFs) to which these equipments belong, is for better management of maintenance schedules, aiming at minimizing scheduled shutdowns, elimination or reduction of untimely disconnections and operational restrictions for the Transmission System of Pará. The choice of the ITs for this dissertation was due to the occurrence of explosions in CTs between the years 2015 to 2016, and some cases of divergences in measurements related to PTs, being that these equipments are installed in the substations belonging to Eletrobrás Eletronorte. The objective is to propose a methodology for IT control based on statistical methods that consider for both equipment (CTs and PTs): maintenance history, installation sites, different families, operating time, systemic occurrences and useful life, to estimate the degree of operational reliability of these equipments based on standard deviation, to be applied in the substations of the Regional Operation of Pará. Aiming at the reliability of complementary diagnoses and support to maintenance planning, in order to reduce the negative financial impact caused by the application of unplanned Variable Parcels (VPs) and/or operational restrictions. Assisting in managerial decisions regarding the prediction of possible substitutions of CTs and PTs that may fail, allowing the guarantee of continuity of the electric power transmission services of Pará applying the concepts of Electric Power Quality, focusing on the quality of services.
Acesso aberto (Open Access)
Impacto técnico e econômico da integração de uma geração distribuída de alta capacidade em um sistema de distribuição com reguladores de tensão em cascata
(Universidade Federal do Pará, 2019-11-14) COSTA, Marcelo Sousa; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
This dissertation analyzes the technical and economical impact of the integration of a high capacity distributed generation (DG) in a distribution system composed of two feeders, both with two cascaded step voltage regulators (SVRs). Distribution networks with the presence of high capacity DG may subject SVR to reverse active power flow scenarios, which, depending on the control modes “Active Bidirectional Flow up to Opposite Limit” and “Reverse Flow by Cogeneration”, result in abnormal situations that lead the SVR to lose its regulating capacity. As a consequence, consumers may be subjected to severe undervoltage or overvoltage. This phenomenon, in which the SVR loses its ability to control the desired bus voltage, is known in technical literature as the reverse power tap changer runaway condition. In addition, high capacity GDs, depending on their location in the distribution system, can cause critical overvoltages. Some actions can be taken to reduce or mitigate this effect, such as distribution system reconfiguration, adjusting the SVR setpoint, and modifying DG control mode. The economic assessment was accomplished for all studied operating scenarios, highlighting technical and financial impacts on the utility and customers.
Acesso aberto (Open Access)
Manutenção preditiva em sistemas elétricos de potência utilizando registros de dispositivos eletrônicos inteligentes (IEDS)
(Universidade Federal do Pará, 2019-11-08) SILVA, Vanderson Geraldo Aranha da; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
Today, electricity generation and transmission utilities are paid for the availability of their transmission functions (FTs) and no longer for what is generated and transmitted in the National Interconnected System (SIN). In this context, more and more efforts are made by the electric energy generation and transmission transmitting utilities so that untimely disconnections do not occur or be avoided. In addition to the loss of revenue when unplanned outages occur in the system, regulators agents, such as the National System Operator and the National Electric Energy Agency, subject utilities to a rigid oversight process. Investments in technology are allowing new directions for the operation and maintenance of power equipment, since high-capacity data-processing devices are enabling optimized predictive maintenance techniques based on the protection, control and monitoring of electrical quantities of the electrical system, as well as guaranteeing the speed and security of information. Intelligent Electronic Devices (IEDs) are multiprocessor systems with hardware and software that continuously work with electrical quantity measurements, protection, command, control, monitoring and have robust memories to record lists of events and waveforms of the analog signals in real time. In this work, real cases will be presented in which FTs shutdowns were avoided with the analysis of the lists of events and waveforms of the IEDs that form the Eletronorte (Pará) substation protection system. This data analysis technique allows the company to perform predictive maintenance of their power equipment in anticipation of the problem, to have useful information to better decision making, as well as to become possible to significantly reduce their financial losses in the operation and maintenance of its electrical system.
Acesso aberto (Open Access)
Medição de módulos fotovoltaicos a sol real por meio de dupla carga capacitiva
(Universidade Federal do Pará, 2018-08-16) BRITO, Thiago Rodrigues; MACÊDO, Wilson Negrão; http://lattes.cnpq.br/3386249951714088
With the increasing demand for electricity worldwide, renewable energy sources are increasingly acquiring space in the world’s energy matrix. In this context, photovoltaic energy has stood out with high growth rates. However, it is necessary to have means to evaluate the performance of the photovoltaic modules. This can be done by means of its characteristic I-V curve, from which the module’s electrical parameters can be evaluated and used as an indicator of possible manufacturing faults, connection or shading. The use of solar simulators is a faster and more reliable to obtain such I-V curve. However, the high costs of a simulator limits access to such measurement, moreover, it is limited to measure only a single PV module. This work seeks to evaluate a methodology for the I-V curve acquisition under outdoor conditions by using two capacitive loads and a reference module as irradiance and temperature sensor. The standard test conditions are obtained by means of IEC 60891 procedures. Silicon technology modules were tested and their results were compared with indoor measurement, using the solar simulator located at GEDAE/UFPA solar laboratory. The results indicated that, depending on which calculation method and considerations related to temperature, this can be a suitable methodology for the measurement of a photovoltaic module.
Acesso aberto (Open Access)
Modelagem e simulação da operação de sistemas de geração com fontes renováveis de energia suprindo minirrede de distribuição
(Universidade Federal do Pará, 2018-01-19) FERREIRA, Andreza Cardoso; GALHARDO, Marcos André Barros; http://lattes.cnpq.br/6672470707462259; PINHO, João Tavares; http://lattes.cnpq.br/0847897516772421
This work is about the development of computational models in Simulink/Matlab workspace, that simulate the operation in islanded or grid connected mode of electrical energy distribution microgrid with hybrid resources, belonging to the Group of Studies and Development of Energy Alternatives (Grupo de Estudos e Desenvolvimento de Alternativas Energéticas - GEDAE) of Universidade Federal do Pará (UFPA), in the Campus of Belém. This paper also describes the hybrid systems and its components (generation systems, power conditioners, microgrid and proposed loads), also the mathematical models, presenting the equations of components applied to dynamic studies. Then the component models that compose the system are validated and analyzed based on the experimental data. It also presents the integration of the proposed models of the hybrid system, simulating three different strategies or modes of operation as a case study. The developed model has the function of helping these studies, simplifying the analysis and providing different possibilities of simulations in short processing time. The principal aim of the work is to make available a computational model able to simulate in detail the behavior of a hybrid system in connected or isolated of conventional power grid operation conditions.
Acesso aberto (Open Access)
Pré-despacho ótimo da geração distribuída para melhoria da operação de redes de distribuição com presença de reguladores de tensão no modo bidirecional
(Universidade Federal do Pará, 2019-09-25) SOUZA, Valéria Monteiro de; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
Electric power systems have been significantly altered over the last few years due to the increased integration of Distributed Generation (DG) into their networks. However, despite the proven advantages associated with the growing penetration of DGs, the modification of the traditional passive nature of such networks incurs several impacts. In order for these systems to have their security, reliability and robustness characteristics ensured, many studies have been developed to mitigate the verified problems caused by this sort of generation and to maximize its benefits. Within this context, it is conducted in this dissertation the integration study of an Independent Power Producer (IPP) in a long rural feeder located in the state of Pará, which contains cascaded step voltage regulators (SVRs) and presents the possibility of switching operations with a neighboring feeder. Upon connection of the IPP, the feeder’s SVRs might be subjected to reverse active power flow by the DG’s injected power as well as by topology reconfiguration of the network, leading them to lose their voltage control capability and indicating the occurrence of runaway condition. Thus, the possible operating scenarios, comprising different SVR configurations and real load profiles, were analyzed via simulations conducted in OpenDSS (Open Distribution Simulator Software). From the assessment of these results, a pre-dispatch optimization strategy for the IPP’s DG control was proposed, aiming not only to prevent the occurrence of runaway condition, but also to help ensure adequate voltage levels and preservation of reliability of the network into which it will be integrated. Perfomance tests of the developed strategy confirmed its feasibility as a tool to mitigate the impacts of high penetration DGs on reconfigurable distribution grids that contain SVR banks.