https://repositorio.ufu.br/handle/123456789/18974 2026-09-20T15:35:21Z 2026-09-20T15:35:21Z https://repositorio.ufu.br/handle/123456789/50286 2026-09-16T06:21:41Z 2025-05-06T00:00:00Z

Title: Medidor de consumo de energia elétrica utilizando o microcontrolador ESP Abstract: Energy efficiency is a crucial aspect in the current context of resource scarcity and environmental concerns, aiming to optimize energy consumption by reducing waste and promoting sustainable use. In this scenario, the electrical energy consumption monitoring system developed with the ESP32 microcontroller and the Peacefair PZEM-004T meter emerges as a viable solution for necessary measurements. The main goal is to provide an efficient tool for real-time energy data measurement and analysis using Bluetooth Low Energy communication. This enables the connection between the ESP32 and the mobile application developed on the Thunkable platform, allowing data visualization on Android and iOS devices. The methodology involved integrating the PZEM-004T with the ESP32 via UART communication. Tests conducted with an 8W LED bulb were validated by comparison with the Atorch S1 meter. Results demonstrated that the system is functional and offers a low-cost, easy-to-implement alternative for monitoring energy consumption in homes and businesses. This approach supports the automation and efficient control of energy, standing out as a practical solution for energy consumption management. Additionally, it promotes awareness of the importance of energy efficiency.

2025-05-06T00:00:00Z https://repositorio.ufu.br/handle/123456789/50188 2026-09-10T06:21:01Z 2026-08-06T00:00:00Z

Title: Uma análise da proteção de sobrecorrente com restrição por tensão (51V) em contexto da minigeração distribuída Abstract: The increasing integration of distributed minigeneration into distribution networks changes the behavior of power systems during faults and creates new challenges for overcurrent protection. In installations with inverter-based sources, the limitation of the current supplied by power converters may hinder the operation of conventional protection functions, requiring the assessment of alternatives that consider additional electrical quantities. In this context, this study analyzes the application of ANSI function 51V, voltage-restrained overcurrent protection, in networks with distributed generation connected at medium voltage. The study comprises an overview of the protection functions associated with the connection of generating facilities, a literature review concerning the application of function 51V, and an analysis of the technical documents adopted by Brazilian distribution utilities. Additionally, simulations were performed in MATLAB/Simulink to evaluate voltage and current behavior under different fault conditions, as well as the sensitivity of functions 51 and 51V. The results showed that the combined analysis of these quantities provides a more comprehensive characterization of fault conditions. In cases where the current contribution from the generating facility remained limited, conventional function 51 showed difficulty in reaching its operating threshold, whereas voltage restraint reduced the operating threshold of function 51V and enabled the identification of conditions not detected through overcurrent alone. Nevertheless, its response remained dependent on voltage-sag severity, fault characteristics, and the selected settings. Accordingly, function 51V proved to be a complementary alternative for improving protection sensitivity in networks with inverter-based generation, especially when fault current is limited by power converters. However, its application requires system-specific studies and coordination with other protection functions.

2026-08-06T00:00:00Z https://repositorio.ufu.br/handle/123456789/50101 2026-09-04T06:31:32Z 2026-08-06T00:00:00Z

Title: Análise de compensação de reativos para melhoria da eficiência energética em um empreendimento do setor comercial Abstract: This study investigates the electrical installation of a commercial consumer unit in the financial sector, highlighting energy efficiency from the construction phase through the completion of the project. Indicators are presented to support the selection of construction alternatives aimed at improving power quality, energy efficiency, and economic performance. In a competitive and sustainability-oriented environment, efficient energy management is essential; however, many projects underestimate the impact of a low power factor (PF). An analysis of utility bills from a 15-month case study identified an increase in reactive energy consumption even with only a limited number of loads connected during the construction phase. Inductive equipment, such as transformers, motors and air-conditioning systems, requires a significant amount of reactive power, reducing the installation's power factor. In parallel, the aggregation of nonlinear loads introduces harmonic distortion into the electrical network, compromising power quality. The main objective of this study is to evaluate the impacts of a low power factor and propose technically and economically feasible solutions. Three alternatives were considered: (i) an automatic capacitor bank; (ii) photovoltaic inverters with reactive power compensation (Q Night) and renewable energy sources; and (iii) rational energy-use strategies for the post-construction phase. The results indicate the potential for reducing tariff penalties and optimizing the use of active power, resulting in improvements in overall energy efficiency. The analyzed consumer unit is classified as Commercial, subclass "Other Services and Activities," under the Green Time-of-Use Tariff (THS Green – A4), supplied by Cemig at 13.8 kV, with a secondary voltage of 380/220 V, located in Uberlândia, Minas Gerais, Brazil, where construction activities were carried out between 2018 and 2020.

2026-08-06T00:00:00Z https://repositorio.ufu.br/handle/123456789/50064 2026-09-04T06:31:11Z 2026-07-29T00:00:00Z

Title: Projeto de sistema de proteção contra descargas atmosféricas para armazém de silo de grande porte com análise comparativa da aplicação de dispositivos ESE em relação ao sistema convencional conforme a ABNT NBR 5419 Abstract: Lightning strikes represent a relevant risk for large agro-industrial structures, especially grain silo facilities, due to their geometric exposure, metallic structures, combustible dust hazards, and the sensitivity of automation, measurement and control systems. This work analyzes a Lightning Protection System (LPS) project applied to the Ouro Safra facility in Araxá–MG, using the technical drawings of the project as a case study. The methodology was developed based on the ABNT NBR 5419:2026 series, including a preliminary risk assessment, evaluation of air-termination, down-conductor and earthing subsystems, equipotential bonding analysis, definition of Lightning Protection Zones (LPZ) and discussion of Surge Protective Device (SPD) coordination. Additionally, the work compares the conventional solution based on Franklin air terminals with the alternative use of Early Streamer Emission (ESE) air terminals, considering technical materials, foreign standards adopted by the manufacturer, a technical consultation with Indelec and application limitations in the Brazilian context. The results indicate that the choice of air terminal type does not eliminate the need for a systemic LPS approach: down-conductors, earthing, electrical continuity, equipotential bonding, LPZ, SPD coordination, inspection and technical responsibility remain essential for the safety of the installation. Therefore, this work contributes by turning a real silo project into an applied technical analysis, highlighting the points that must be maintained, verified or complemented when comparing a conventional solution with an ESE alternative.

2026-07-29T00:00:00Z