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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Acesso aberto (Open Access)
Análise da metodologia para definição dos limites de continuidade dos conjuntos elétricos das distribuidoras de energia elétrica no Brasil
(Universidade Federal do Pará, 2024-10-10) OLIVEIRA, Loreddana Monteiro Bandeira de; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
The definition of continuity indicator limits for electrical network sectors in electricity distribution companies represents the primary regulatory aspect of electricity supply quality, directly impacting consumer tariffs and investment decisions made by electric companies in electricity distribution systems. In the context of electricity sector regulation, maintaining continuity indices at appropriate levels is crucial to improving supply for consumers and ensuring tariff accessibility. This study presents the Brazilian regulation of collective continuity indicators for electricity supply, developed by the National Electric Energy Agency (ANEEL), from its implementation to the present, analyzing how each regulatory change has influenced the performance and development of the Brazilian electricity sector, with particular emphasis on the State of Pará. Pará exhibits unique continuity indicators compared to other states due to its concession area characteristics, including access challenges, long distances, and low population density. ANEEL uses benchmarking among distribution companies’ electrical sectors to establish performance targets at the end of each tariff cycle; however, the current method for setting regulatory limits does not account for factors that directly impact operational management or specific regional characteristics. This dissertation aims to analyze the current methodology for defining continuity limits for the electrical network sectors of electric companies in Brazil.
Acesso aberto (Open Access)
Análise de Desempenho de Meta-heurísticas Aplicadas ao Problema de Restauração de Redes de Distribuição.
(Universidade Federal do Pará, 2020-02-20) BATISTA, Vítor dos Santos; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
In the last years, several meta-heuristics have been used to solve the problem of restoring distribution systems efficiently. Among them, the Multiobjective Evolutionary Algorithm with Node-depth encoding (MEAN) stands out, which together with Node-Depth Encoding (NDE) makes a great advance in the field. All this because the NDE makes changes on the topology of the distribution system without losing radiality and reestablishing the power supply for all disconnected loads after the fault. Due to the lack of exploration of other meta-heuristics that use NDE as a data structure, this work aims to evaluate a performance analysis comparing MEAN with three other meta-heuristics, Tabu Search, Artificial Bee Colony and Evolutionary Strategies. The analysis was performed in three distribution systems the84-bus, 119-bus and 135-bus.s
Acesso aberto (Open Access)
Análise de estabilidade transitória em geradores distribuídos: considerações sobre a proteção 78PS.
(Universidade Federal do Pará, 2024-09-09) HERINGER, Wesley Rodrigues; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
This dissertation aims to present the transient stability analysis in Distributed Generators, considering the performance of 78PS protection, against loss of synchronization. In this context, the studies developed in this work will be considered For two distinct real cases of two cogeneration plants with synchronous generators of different powers, being a sugar-alcohol plant, which will soon be connected to An extensive rural feeder of Equatorial Energia’s Paragominas 34.5 kV substation, being in the second case analyzed a fruit pulp industry that uses biomass Resulting from the processes as fuel for the steam boiler, which connects to the a turbine, to drive a generator. In turn, this system will be interconnected in a predominantly urban feeder, in a distribution substation of 13.8 kV at Castanhal in the interior of Pará. The analyses are carried out by means of complete simulation in the time domain through software Anatem© , considering two modes of voltage control of synchronous machines: 1) without voltage control; and 2) with voltage control. The studies provide the margins of transient stability of the machines and considerations on the protection against the loss of timing of synchronous generators. The results indicate that the use of the voltage control mode of the automatic voltage regulator and the coordination between the protection of the internal feeders of the industrial consumer and the protection of the plant are fundamental to ensure the maintenance of the timing of distributed generation.
Acesso aberto (Open Access)
Análise magnética e mecânica em transformadores sob correntes de energização e energização solidária
(Universidade Federal do Pará, 2019-10-01) LIMA, Diorge de Souza; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
The power transformer is one of the most important equipment in the electric power system, allowing the feasibility of connecting the generating centers to the consumer centers, even over long distances. Reliable and continuous operation is of fundamental importance for service maintenance and is subject to various types of disturbances that can lead to failures. In this perspective, studies of the dynamic behavior of transformer windings through computer simulations have been widely used to safely and accurately evaluate their operation. Therefore, this paper presents the methodology for research on a 50 MVA power transformer using the finite element method for static and time domain analysis. Thus, the study was performed by means of magnetic-mechanical couplings. In the first analysis (circuit study), the ATPDraw software was used to obtain the behavior of the inrush current and solidarity energization during the transformer bank energization. Therefore, in the ANSYS MAXWELL software magnetic studies were performed. For this, a real 3D model was used (taking into account the characteristics of the lamination core and windings, being in disc). Thus, the results of the behavior of magnetic induction and magnetic forces in the windings of the equipment are presented. Finally, in the ANSYS STRUCTURAL software, structural (mechanical) studies were performed. Also, as before, a close-to-real 3D model was used, presenting as results the behavior of the total deformation in the winding, the mechanical stress suffered and the degree of safety during the occurrence of energization. The static studies were considered three operating conditions: nominal condition, sympathetic inrush and inrush current. For the nominal condition, the equipment's plate data was used, for the energizing condition (sympathetic inrush and inrush current) the largest amplitude obtained during the simulation was used. It is noteworthy that for the time domain analysis, only the condition of the inrush current was analyzed, both for the high computational cost required and for being the worst condition in the static analysis.
Acesso aberto (Open Access)
Aplicações de controle preventivo baseadas em árvore de decisão para aumentar a capacidade de sobrevivência a afundamentos de tensão dos geradores de indução duplamente excitados em sistemas de potência
(Universidade Federal do Pará, 2018-09-21) VIEIRA, Dione Jose Abreu; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
The development of a preventive control methodology to increase the capacity of voltage sag recovery (Fault Ride Through Capability (FRTC)) of a doubly-fed induction generator (DFIG) connected in an electrical network is presented. This methodology, which is based on the decision trees (DT) technique, assists with monitoring and support for security and preventive control, ensuring that wind systems remain connected to the power system even after the occurrence of disturbances in the electric system. Based on offline studies, DT discovers inherent attributes of the FRTC scenario related to electrical system behavior and provides a quick prediction model for real-time applications. From the obtained results, it is possible to check that the DFIG is contributing to a system’s operation security from the availability of power dispatch and participation in the voltage control. It is also noted that the use of DT, in addition to classifying the system’s operational state with good accuracy, also significantly facilitates the operator´s task, by directing him to monitor the most critical variables of the monitored operation state for a given system’s topological configuration.
Acesso aberto (Open Access)
Avaliação da distorção harmônica total de tensão no ponto de acoplamento comum industrial usando o processo KDD baseado em medição
(Universidade Federal do Pará, 2018-03-27) OLIVEIRA, Edson Farias de; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
In the last decades, the transformation industry has provided the introduction of increasingly faster and more energy efficient products for residential, commercial and industrial use, however these loads due to their non-linearity have contributed significantly to the increase of distortion levels harmonic of voltage as a result of the current according to the Power Quality indicators of the Brazilian electricity distribution system. The constant increase in the levels of distortions, especially at the point of common coupling, has generated in the current day a lot of concern in the concessionaires and in the consumers of electric power, due to the problems that cause like losses of the quality of electric power in the supply and in the installations of the consumers and this has provided several studies on the subject. In order to contribute to the subject, this thesis proposes a procedure based on the Knowledge Discovery in Database - KDD process to identify the impact loads of harmonic distortions of voltage at the common coupling point. The proposed methodology uses computational intelligence and data mining techniques to analyze the data collected by energy quality meters installed in the main loads and the common coupling point of the consumer and consequently establish the correlation between the harmonic currents of the nonlinear loads with the harmonic distortion at the common coupling point. The proposed process consists in analyzing the loads and the layout of the location where the methodology will be applied, in the choice and installation of the QEE meters and in the application of the complete KDD process, including the procedures for collection, selection, cleaning, integration, transformation and reduction, mining, interpretation, and evaluation of data. In order to contribute, the data mining techniques of Decision Tree and Naïve Bayes were applied and several algorithms were tested for the algorithm with the most significant results for this type of analysis as presented in the results. The results obtained evidenced that the KDD process has applicability in the analysis of the Voltage Total Harmonic Distortion at the Point of Common Coupling and leaves as contribution the complete description of each step of this process, and for this it was compared with different indices of data balancing, training and test and different scenarios in different shifts of analysis and presented good performance allowing their application in other types of consumers and energy distribution companies. It also shows, in the chosen application and using different scenarios, that the most impacting load was the seventh current harmonic of the air conditioning units for the collected data set.
Acesso aberto (Open Access)
Avaliação da segurança de sistemas de potência para múltiplas contingências usando árvore de decisão multicaminhos
(Universidade Federal do Pará, 2017-09-15) OLIVEIRA, Werbeston Douglas de; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
The search for effective ways to promote the secure operation of power systems and to increase its understanding by operators has encouraged continuous research for new techniques and methods that can help in this task. In this paper, it is proposed an approach to assess power system operation security for multiple contingencies using a multiway decision tree (MDT). The MDT differs from other decision tree techniques for establishing, in the training step, one value of the categorical attributes by branch. This approach proposes the use of topologies (contingencies) as categorical attributes. In this way, it improves interpretability regarding the power system operational state, as the operator can see clearly the critical variables for each topology, such that the MDT rules can be used in aiding the decision-making. This proposal was used for security assessment of two test systems, the IEEE 39-bus system and the Northern part of the Brazilian Interconnected Power System (BIPS), and BIPS was tested with real data from one day operation. The proposed MDT-based technique demonstrated superior performance, with a set of simple and clear rules. It was also performed a comparison of the obtained results with other techniques based on DT and it turned out that MDT has resulted in a simpler procedure for power system security classification with good accuracy.
Acesso aberto (Open Access)
Avaliação de algoritmos evolucionários multiobjetivo para o problema de alocação de bancos de capacitores na presença de harmônicos
(Universidade Federal do Pará, 2017-08-10) KATAOKA, Vitor da Silva; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
The rapid growth of urban areas bring, as a consequence, an increase in the amount of loads connected to the distribution grids. Furthermore, the increase in the demand implies in equal raise in reactive loads, which are known to cause losses in the network. Thus, the utilities have a great challenge ahead, as the dynamics of the load require a greater effort in terms of expansion and improvements of the grid. In an attempt to mitigate the problems caused, the allocation of capacitor banks can become a practical, economical and technically robust solution. Nevertheless, it is extremely important to analyze the sizing and positioning of the banks, in order to achieve the best possible outcome. In parallel, the increasing use of nonlinear loads cause harmonics to appear in the system. When in conjunction with capacitor banks, it is possible to develop the far more dangerous phenomenon of resonance, where the amplitude of some of the harmonics goes beyond acceptable limits, resulting in undesirable effects. In this context, this work proposes a comparison between two multiobjective optimization tehcniques, NSGA-II and SPEA2, to solve the problem of sizing and placement of capacitor banks in electric energy distribution grids, considering the effects of harmonics produced by nonlinear loads.
Acesso aberto (Open Access)
Avaliação do impacto da produção eólica na reserva operativa de curto e longo prazo utilizando séries temporais
(Universidade Federal do Pará, 2019-05-30) SANTOS, Fernando Manuel Carvalho da Silva; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; BRANCO, Tadeu da Mata Medeiros; http://lattes.cnpq.br/8911039344594817
One of the main concerns of a system planner is to size generation equipment, mainly for meeting the load growth and to achieve certain spinning reserve requirements. In general, generation systems must be sized with sufficient capacity, flexibility and robustness to respond to several operational challenges. However, the volatility and variability that comes from renewable generation is a relatively recent concern for the system planners. This thesis evaluates the potential of diverse wind power patterns to balance the global power output of wind farms using the concept of operating reserve assessment. To achieve this, operating reserve assessment models are utilized to evaluate bulk generation systems under several conditions of wind power geographic distribution. Different wind behavior patterns and wind power penetration levels are tested using a modified configuration of the IEEE RTS-96 and a planning configuration of the Portuguese Generation System. The results highlight that on a large country scale system with different wind characteristics, the diversification of wind behavior might be conducive to a compensation of wind power fluctuations, which may significantly decrease the need for system operating reserves. This effect is verified using probability distribution functions of reserve needs estimated by sequential Monte Carlo simulations (SMCS), such that useful information regarding generation capacity flexibility is drawn from the evaluations.
Acesso aberto (Open Access)
Avaliação dos impactos da recarga de veículos elétricos na vida útil de transformadores de distribuição
(Universidade Federal do Pará, 2023-10-30) BARROS, Amanda Monteiro Pinto; AFFONSO, Carolina de Mattos; http://lattes.cnpq.br/2580696185627481
The objective of this dissertation is to provide a comparative assessment of the impacts caused by charging practices of short-range and long-range electric vehicles under different power levels on life expectancy of distribution transformers. This research is based on the use of real data of residential energy consumption collected from the region of East Midlands, United Kingdom, as well as electric vehicle charging data collected through an experimental project also conducted in the United Kingdom. This study examines transformer hottest-spot temperature and evaluates the transformer accelerated aging factor that influences the equipment's lifespan according to the thermal model presented in IEEE Standard C57.91. As a result, this study reveals that the effects caused by long-range vehicles are more pronounced, as they charge at higher power level and the charging process is longer. As the penetration level of electric vehicles increases, transformer load and hottest-spot temperature increases, especially during winter season, where residential demand escalates. In the case of vehicles with 75 kWh, penetration levels starting from 30% already causes severe violations on transformer hottest-spot temperature, contributing to a reduction in the equipment's lifespan.
Acesso aberto (Open Access)
Avaliação probabilística do impacto da recarga rápida de veículos elétricos nos sistemas de distribuição de energia elétrica
(Universidade Federal do Pará, 2024-11-13) HERNÁNDEZ GÓMEZ, Oscar Maurício; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
The mass adoption of electric vehicles (EVs) is transforming the automotive sector, driven by environmental concerns and technological advancements. Governments and companies are investing in the expansion of charging networks, focusing on fast charging to meet the growing demand. Developing a robust infrastructure of charging stations is essential to eliminate “range anxiety” and encourage the transition to EVs. Fast charging is crucial for the success of vehicle electrification. It allows batteries to be charged much more quickly than conventional charging, increasing convenience for users and improving the overall user experience. As more fast-charging stations are installed, consumer confidence in EVs grows, paving the way for a more sustainable future. With a well-distributed fast-charging network, EVs become a practical alternative to fossil fuel-powered vehicles, accelerating the transition to greener mobility. However, fast charging of EVs can cause technical impacts on medium voltage networks. The high current demand can result in voltage drops, especially in areas with weaker distribution infrastructure. Transformers can be overloaded, reducing their lifespan and increasing the risk of failures. Excessive heating of conductors due to high current can also cause losses and damage cables. These challenges highlight the need for proper planning and investments in electrical infrastructure to support the increase in fast charging. A probabilistic analysis of the impact of fast charging on medium voltage networks is crucial. Energy demand varies throughout the year due to seasonal factors, such as the use of air conditioning in summer and heaters in winter. Fast charging adds a considerable load to the network, which can coincide with these demand peaks, exacerbating management challenges. The installation of multiple charging points can cause voltage fluctuations and overloads. Probabilistic analysis helps predict these impacts and develop mitigation strategies by simulating charging scenarios and user behaviors. This allows for more precise infrastructure planning, including network reinforcements and improvements to ensure supply reliability. This thesis proposes a probabilistic methodology to evaluate the impact of fast charging of electric vehicles on medium voltage distribution networks, considering voltage drops, network element loading, and regulator tap changes. Using the Power Factory software by DIgSILENT©, a real feeder in Brazil is simulated, analyzing different case studies. Three fast charging stations (FCS) are connected, each with six charging points of 100 kVA, totaling 600 kVA per EP. The charging profile of the EPs is programmed with stochastic variables. Finally, a Volt/Var control strategy is presented to mitigate the impact on voltage drops and regulator tap changes, allowing reactive power injection without the need for communication between charging points.
Acesso aberto (Open Access)
Contribuição da geração solar fotovoltaica na certificação de edificações públicas pelo RTQ-C e em edifícios de energia zero: laboratório de ensino da Universidade Federal do Pará
(Universidade Federal do Pará, 2020) SILVA, Hosaías Alves dos Prazeres; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
This work presents the contribution of solar photovoltaic generation as a renewable source in the methodology for obtaining Level A Label in Energy Efficiency certification and for the transformation into a Zero Energy Building, being applicable to buildings and public teaching laboratories. The methodology step-by-step essentially consists of two stages: the first, through an energetic diagnosis of the building analyzed, following the guidelines established in the Technical Regulation on Quality in Commercial, Service and Public Buildings - RTQ-C (in portuguese), resulting in a proposal of energetic, financial and environmental improvement processed with the aid of the RETScreen® software; and the second, dimensioning a photovoltaic solar generation system, based on local measurement data and the Meteonorm® software, as a bonus for obtaining the Level A Label of the RTQ-C levels and with energy production capacity that makes the energetic balance of the building as positive, making it a Zero Energy Building. In order to contextualize the relevance of the work and update the reader in the state of the art applicable to the methodology, a bibliographic review is presented, directed to the benefits of Energy Efficiency in public buildings and to the RTQ-C; to the current scenario, application and contribution of Solar Photovoltaic Energy in sustainable development, in obtaining nationally and internationally recognized classifications for public buildings; and the concepts currently used by the academic community to characterize Zero Energy Buildings. The bibliographic review and methodology were applied in a case study of the Laboratory of Electrical and Computer Engineering – LEEC (in portuguese), located at the Campus Guamá of the Federal University of Pará, with presentation of the energetic, financial and environmental results, showing that it is a solution to be applied in public institutions and buildings that have available space and similar infrastructure to that of the LEEC.
Acesso aberto (Open Access)
Contribuição do controle secundário de tensão aplicado em um parque eólico composto de aerogeradores dfig à estabilidade de tensão de longo-prazo
(Universidade Federal do Pará, 2019-08-30) MATOS, Kayt Nazaré do Vale; AFFONSO, Carolina de Mattos; http://lattes.cnpq.br/2228901515752720; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
This thesis investigates the use of secondary voltage control (SVC) in a wind park based on doubly fed induction generator (DFIG) and its effect on long-term voltage stability. The wind park consists of several wind turbines is modeled as an DFIG equivalent model. Initially, the performance of the SVC applied to wind park is compared with the case when only the primary voltage control (PVC) is adopted. A detailed analysis is conducted with time-domain simulations, considering high and low wind speed regimes, control variable limits of wind generators, static and dynamic loads, as well as dynamic models of overexcitation limiter (OEL) and load tap changing (LTC) transformer. Based on the results, the use of secondary voltage control in a DFIG-based wind park can postpone long-term voltage collapse of power system. Further, an adverse situation was observed showing that SVC can lead the grid-side converter (GSC) of DFIG to absorb reactive power from the electric grid and lose the capability of injecting reactive power in the grid. Thus, two novel auxiliary control strategies inserted in the GSC control loop are presented to prevent reactive reverse flow in the GSC, as well as forcing the provision of reactive power to the system via the GSC. The results indicate the effectiveness of the auxiliary control strategies in postponing the voltage collapse and increase the voltage stability margin of the system.
Acesso aberto (Open Access)
Desempenhos térmico e energético de uma edificação na região amazônica brasileira
(Universidade Federal do Pará, 2018-09-06) AGUILAR, Heliana Maria Ceballos; PINHO, João Tavares; http://lattes.cnpq.br/0847897516772421
This work presents an innovative proposal of integration of several strategies to reduce energy consumption, where the impact of each one of them is evaluated individually, and all together, in the thermal, energetic and economic performance of a building located in the Brazilian Amazon Region. High temperature and humidity characterize this region climatically, where achieving adequate comfort conditions implies a high demand for energy for air conditioning systems. Different Energy Conservation Measures are evatuated in order to achieve a better use of daylighting; and to reduce thermal loads for cooling, with the installation of a thermal insulation material in the eastern and western walls, and a thermal insulation and air chamber in the roof, which are the external surfaces that receive higher solar radiation in the building. Additionally, various photovoltaic generation systems are considered, one of which is integrated as an architectural element and another adapted on the roof of the building. In the building, two types of analysis are conducted: dynamic and static. For the dynamic analysis, the EnergyPlus software is used to know its thermal and energy consumption performances, analyzed for the entire year and for the design day, and the Daysim/Radiance software to know the autonomy of daylighting attained, using data measured with an on-site meteorological station. Concerning the static analysis, the level of energy efficiency is evaluated by the prescriptive method according to the current national regulations. Subsequently, the same building is simulated for the nine capital cities of the states of the Legal Brazilian Amazon Region, with the aim of knowing its energetic performance and the economic feasibility depending on the climatic characteristics and electrical energy tariffs of each city. With the assessments performed, it is determined that the ECM have a direct and significant influence on the reduction of the thermal load for cooling, through the reduction of radiation effects, the shading in the eaves and the reduction of the transmittance of the surfaces treated. The possibility of maximizing the daylight in internal spaces, to improve the comfort of the users is also verified, allowing better performance and energy savings with artificial lighting. In terms of energy consumption and economic feasibility, the ECM achieve an annual energy savings of 52 % in the building taken as a case study, and the solutions adopted show a good return on financial investment, and are also suitable for energy saving and economically feasible in regions with similar climatic characteristics.
Acesso aberto (Open Access)
Desenvolvimento a eventos discretos de um controlador de balanceamento de fases para sistemas legados de baixa tensão e microgrids
(Universidade Federal do Pará, 2019-06-10) VILCHEZ, José Ruben Sicchar; SILVA, José Reinaldo; http://lattes.cnpq.br/9317869378701106; COSTA JÚNIOR, Carlos Tavares da; http://lattes.cnpq.br/6328549183075122
In the up-grading of the legacy low-voltage system as urban microgrids, phase - balance algorithm development becomes useful and important to ensures robust and reliable load balancing, establish an efficient automation workflow among consumers, the legacy lowvoltage grid and the supervision center of the distribution network of electrical power. It constituting an alternative. This may constitute an alternative phase-balancing control system based on consumer units dynamic switching rather than electrical current injection by microgrids. Formal automation design of these algorithms become an interesting milestone for performance evaluation and properties validation for their insertion in the new microgrid architecture. This may evaluate the system's reliable performance when verifying dynamic properties as well as, the univocal solutions that ensure load transfer and load stability robustness of low-voltage grid, without operation interruptions neither conflicting events. This work, proposes a new phase-load- balancing control system based on combined algorithms resulting from a Hierarchical Petri net system design. Through this model it was obtained an optimized and reliable automated workflow of load balance in the low-voltage grid phases, with an efficient choice of consumer units for the switching process, aiming to obtain a robust steady state of load against unbalances between phases, and neutral current minimized. From the model obtained called “Transformer- Phase Balancing Controller” (T-PBC) were developed four integrated algorithms: the Load Transfer Algorithm, that calculates the load imbalance level and power to be transferred in the transformer phases; the Consumption Diagnose Algorithm, that identifies the load levels margins in each consumer unit; the Consumption Forecast Algorithm, that forecast the monthly energy future states in consumers; and the Switch Selection Algorithm, that selects the consumers units to switch based on the future state of energy consumption, the load level margins and the average of the energy future states. Based on the performance results, it was obtained, the efficient reduction of the neutral current and the load average unbalance in the low-voltage grid phases, with load stability robustness about three months, making it an efficient alternative system against load unbalances in the legacy low-voltage grid and the microgrids.
Acesso aberto (Open Access)
Detecção de faltas de alta impedância em redes aéreas de distribuição: testes experimentais em laboratório e análises no domínio do tempo e da frequência
(Universidade Federal do Pará, 2023-07-04) SOUSA, Ádrea Lima de; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913
The present work deals with the analysis of high impedance faults (HIFs) in overhead distribution networks. A comprehensive and in-depth study is conducted on this type of fault, as well as on some existing methods to detect HIFs. Next, the laboratory developed for experimental testing of HIFs is explained, which replicates the three-phase, three wire medium voltage distribution network with solidly grounded system at the primary substation typically used in Brazil. From the laboratory, 127 tests were performed in 18 different scenarios, including shunt faults and series shunt faults on the source side. In order to perform a comparative analysis with the existing literature on high impedance fault detection based on harmonics, the harmonic spectrum was evaluated, based on even harmonics, odd harmonics (especially the third order), and the angle of the third harmonic, obtained through the Fast Fourier Transform (FFT). The main contribution of this work lies in evaluating the peculiarities of the harmonic spectrum of voltage and current signals obtained from experimental laboratory tests for different soil topologies and tree branch configurations, and their correlation with the signal in the time domain. This provides an important foundation for the development of HIF detection algorithms. The results obtained in the analysis revealed that shunt and series shunt high impedance faults exhibit distinct behaviors in the harmonic spectrum and time domain, and a large portion of the tests performed does not fall within the thresholds established in the literature. Furthermore, it should be noted that the evaluation of the harmonic spectrum of voltage was carried out, which is usually not considered in HIF detection algorithms.
Acesso aberto (Open Access)
Diagnóstico de eficiência energética com base no INI-C e RTQ-C: estudo de caso da envoltória do Clube de Ciências da UFPA
(Universidade Federal do Pará, 2022-02-09) GOMES, Raphaele Samua Barata; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
Save energy is an emergency and it is just cut costs. Worldwide that theme has been mentioned and discussed through agreements made among countries since 1970 forward reducing the impacts of energy consume and also focused on constructions that consume about 60% of global electricity according to United Nations Environment Programme (UNEP). From here on programs and boosts came up for this sector. In 2001 in Brazil, the program called Brazilian Labeling Program (PBE) of National Institute of Metrology, Standardization and Technology (INMETRO) was created to try and to classify household appliances, electronics, vehicles and others in a group of 24 categories about their energetic efficiency. The national methodology of labeling buildings specify the technical requirements, guidelines classification of energetic sustainable construction based on a regulatory document for commercial buildings, public and services, and another for residential buildings (BRAZIL, 2010). The Technical Normative of Quality for Energetic Efficiency Level of Commercial Constructions Services and Public (RTQ-C) has standards and methods for evaluation and classification commercial, service and public constructions as well as their energetic efficiency with the objective of labeling them. The INMETRO approved on March 9th of 2021 a new Normative instruction for Energetic Efficiency of Commercial, Services and Public Constructions (INI-C) that improves the RTC-C. In this Science Club of UFPA was evaluated according to simplified method from INI-C and prescriptive method from RTQ-C of in order to compare their results and identify the differences on update regulations.
Acesso aberto (Open Access)
Estimação das parcelas de contribuição de cargas não lineares na distorção harmônica de tensão de um barramento de interesse do sistema elétrico de potência utilizando rede neural artificial
(Universidade Federal do Pará, 2019-09-06) MANITO, Allan Rodrigo Arrifano; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
This work presents a methodology to estimate the non-linear loads contribution on voltage harmonic distortion at a bus of interest in the electric power system. The estimation process is carried out through the development of a model based on artificial neural networks (ANN) added to a sensitivity analysis in neural network input. The ANN model input is constituted by the non-linear loads harmonic currents considered in the studied system, and the ANN output corresponds to the harmonic voltage values in the bus under study, for the same harmonic frequency. The study is carried out for each harmonic order individually and the data required for the construction of the model as well as for the results validation have been obtained from synchronized measurement campaigns and by computational simulation, using harmonic load flow studies. Comparisons between reference results through computational simulation with the results obtained by neural model are carried out and it is observed that the developed methodology is able to classify correctly the impact of non-linear loads in the voltage distortion at a bus of interest of the electric system. Additionally, the effectiveness of the methodology is tested in two real systems in order to verify the good performance of this methodology considering real data obtained during measurement campaigns.
Acesso aberto (Open Access)
Estimador de estado harmônico trifásico incorporando Saturação de transformadores
(Universidade Federal do Pará, 2019-06-28) SOARES, Thiago Mota; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
Acesso aberto (Open Access)
Estrutura de redes neurais auto-associativas aplicadas ao processo de identificação de equipamentos elétricos em sistemas de monitoramento não intrusivo de cargas
(Universidade Federal do Pará, 2019-10-23) MORAIS, Lorena dos Reis; CASTRO, Adriana Rosa Garcez; http://lattes.cnpq.br/5273686389382860
The pursuit of reducing and rationalizing electricity consumption is increasingly becoming a priority for all consumers worldwide. Residential environments are responsible for a large part of electricity consumption. Non-intrusive load monitoring systems were created with the aim of helping consumers, providing the possibility of obtaining information about the individual consumption of equipment and thus allowing a monitored consumption and the consequent increase in energy efficiency. In a Non-Intrusive Load Monitoring System, four steps are critical: acquiring aggregate data through a single sensor, detecting equipment on / off events from the aggregate load, extracting disaggregated signal characteristics and the identification of equipment based on the characteristics extracted from the disaggregated signal. In this context, this work proposes a new methodology for identification of electrical equipment in a residential environment employing a competitive structure of Auto-Associative Neural Networks. The proposed system is based on power signal measurements obtained from equipment on / off events. To test the proposed methodology 3 scenarios were developed using 3 different public databases. Due to the good results achieved, analyzed using statistical metrics, it is evaluated that the proposed methodology is able to efficiently perform the task of identifying electrical equipment, thus contributing to the development of future non-intrusive monitoring systems. meet market demands.