https://repositorio.ufu.br/handle/123456789/5464 2026-04-23T04:33:08Z https://repositorio.ufu.br/handle/123456789/48387 Title: LoRa e IEEE 802.15.4 a 2,4 GHz: Análise Comparativa de Comunicação Sem Fio e Viabilidade Energética com Fontes Renováveis em Cenários Industriais Abstract: The Fourth Industrial Revolution, characterized by the interconnection of systems, relies on the Internet of Things (IoT) as a fundamental pillar, fostering the convergence between the physical and digital worlds. Within the Industrial IoT (IIoT) landscape, technologies such as ZigBee and LoRa have driven the adoption of monitoring solutions due to their flexibility and low power consumption. However, ensuring network reliability and energy autonomy remains a critical challenge for scalability. In this context, this study presents a comparative analysis of two wireless solutions operating in the 2.4 GHz ISM band: the IEEE 802.15.4 standard, implemented via the AT86RF233 transceiver, and the LoRa physical layer (PHY), utilizing the SX1280 transceiver. Specifically, the work evaluates the robustness of LoRa’s proprietary modulation against the standardized IEEE protocol, while also investigating the feasibility of applying photovoltaic energy harvesting. Experimental results indicate that IEEE 802.15.4 exhibited greater stability in packet delivery, maintaining success rates above 90% at distances up to 150 meters, albeit with significantly higher energy consumption due to the external amplification required to reach 12 dBm. In contrast, LoRa technology demonstrated superior energy efficiency, consuming approximately half the current in the tested configurations, while maintaining competitive transmission rates. Additionally, the technical feasibility of photovoltaic panels was confirmed, as they successfully supplied the full energy demand during continuous transmission under high solar irradiance conditions. 2026-02-06T00:00:00Z https://repositorio.ufu.br/handle/123456789/48306 Title: Uma arquitetura de ambiente virtual interativo suportada por imagens aéreas e esféricas para visualização de dados e de diagrama unifilar de subestações de energia elétrica Abstract: Electrical substations are critical infrastructures whose complexity and high voltage levels require solutions that ensure safety, agile navigation, and efficient maintenance. This research developed a navigable digital platform designed to integrate and visualize orthomosaic images generated by drones, CAD (Computer-Aided Design) plans, and spherical georeferenced images captured at different points in the substation yard. The interactive interface allows switching between layers and links each piece of equipment to its single-line diagram, enabling immediate access to technical specifications and safety guidelines. The methodology involves visual data capture, photogrammetric processing, georeferencing via control points, and integration into a database with each asset's attributes. The results demonstrate that virtual navigation reduces the time needed for inspection, accelerates the identification of critical equipment, and improves communication between teams, speeding up response times in preventive and corrective maintenance. The usage of drones, digital modeling, and spherical images in a unified environment represents a significant advance in modernizing the substation operation and monitoring practices, promoting greater efficiency, safety, and reliability in the management of these critical assets. 2025-12-19T00:00:00Z https://repositorio.ufu.br/handle/123456789/48301 Title: Uma contribuição dos impactos do carregamento de veículos elétricos em redes de distribuição: análise técnica e uma proposta tarifária para mitigação Abstract: The increasing electrification of transportation and the rapid expansion of photovoltaic distributed generation have introduced significant operational challenges to electric distribution networks, particularly regarding power quality, hosting capacity, and demand management. In this context, this dissertation systematically investigates the technical impacts associated with the integration of residential electric vehicle chargers into a real distribution feeder obtained from the Geographic Database of the Utility. The study focuses on 7 kW residential chargers, which are predominant in domestic applications, and employs a probabilistic modeling approach to represent the stochastic behavior of EV charging profiles. The proposed methodology integrates the OpenDSS software with the Python environment, enabling Monte Carlo simulations for different levels of EV penetration. Key operational indicators are analyzed, including transformer overloading, technical losses, voltage profiles, and phase imbalance. The results show that the simultaneous penetration of EV chargers can lead to violations of regulatory limits, increasing system losses, reducing voltage levels, and causing overloading in low-capacity transformers. Beyond the technical assessment, this dissertation discusses tariff structures applicable to electromobility, with emphasis on Time-of-Use pricing models and international charging strategies. Based on this analysis, a mitigation strategy is proposed by shifting the probability distribution of charging start times toward periods of higher solar irradiance. The simulations demonstrate that this approach reduces net feeder demand, alleviates transformer loading, improves voltage profiles, and increases the system’s EV hosting capacity. The findings highlight the importance of tariff-driven demand management and reinforce the need for coordinated strategies to support the sustainable integration of electric mobility into distribution networks. 2026-01-28T00:00:00Z https://repositorio.ufu.br/handle/123456789/48277 Title: Avaliação comparativa da resistividade do solo em projetos de aterramento: análise de terrômetro e resistivímetro em SEV e seus efeitos sobre parâmetros de segurança via Software XGSLab Abstract: A resistividade do solo é um dos principais parâmetros no projeto e na avaliação de sistemas de aterramento, influenciando diretamente a resistência de aterramento e os níveis de tensão de toque e de passo. Nesse contexto, a correta caracterização elétrica do solo é fundamental para garantir a segurança de pessoas e equipamentos. Este trabalho apresenta uma investigação comparativa entre medições de resistividade do solo realizadas com terrômetro e resistivímetro, analisando as diferenças entre os resultados obtidos e seus impactos no dimensionamento de sistemas de aterramento. Foram realizadas medições experimentais em cinco locais distintos, utilizando o método de Wenner, com diferentes espaçamentos entre eletrodos. Os resultados indicaram que o terrômetro tende a fornecer valores de resistividade inferiores aos obtidos com o resistivímetro, sendo esse comportamento mais acentuado para maiores espaçamentos entre eletrodos. Observou-se que, para espaçamentos superiores a 16 m, o terrômetro apresenta perda significativa de confiabilidade, com erros da ordem de 30%. A partir dos dados experimentais, foram realizadas análises computacionais no software XGSLab, aplicadas a sistemas reais de aterramento de uma usina fotovoltaica, de um hospital e de uma subestação de energia elétrica. As simulações demonstraram que, em solos de baixa resistividade, as variações nos valores medidos exercem menor influência sobre a resistência final de aterramento, enquanto em solos de alta resistividade essas diferenças resultam em variações expressivas na resistência de aterramento e nos níveis de tensão de toque e de passo. Os resultados evidenciaram ainda que o uso de valores de resistividade obtidos com terrômetro tende a subestimar a resistência de aterramento e as tensões de toque e de passo, podendo conduzir ao subdimensionamento dos sistemas e a uma avaliação excessivamente otimista das condições de segurança. Conclui-se que o terrômetro é mais indicado para medições de pequeno porte e espaçamentos reduzidos, enquanto o resistivímetro se mostra mais adequado para estudos que demandam maior precisão e profundidade de investigação. 2026-02-06T00:00:00Z