https://repositorio.ufu.br/handle/123456789/5464 2026-08-05T05:24:17Z 2026-08-05T05:24:17Z https://repositorio.ufu.br/handle/123456789/49153 2026-07-30T06:26:19Z 2026-05-12T00:00:00Z

Title: Análise comparativa entre geração de eletricidade e produção de biometano a partir do biogás: fundamentação teórica e estudo de caso Abstract: The global climate crisis has intensified the need for measures aimed at mitigating Greenhouse Gas emissions, within the context of the energy transition, in which the search for technological alternatives capable of promoting greater sustainability and efficiency in energy generation has become imperative, with emphasis on the replacement of fossil-based sources by renewable ones. In this context, the objective of this work is to perform a techno-economic comparative analysis between two biogas utilization routes: electricity generation and biomethane production. For this purpose, a real biogas plant located in the interior of Brazil is used as a case study, allowing the evaluation of the alternatives in a practical operational context. The results indicate that, although electricity generation is a consolidated alternative integrated into the Free Energy Market, it remains subject to the volatility of the Settlement Price for Differences and to the hydrological conditions of the country. From an economic perspective, the biomethane route presents a promising revenue structure, with lower exposure to Price for Differences fluctuations that affect electricity generation. The analysis is characterized as a replacement decision, in which an incremental cash flow approach is adopted to compare the alternatives. Thus, cash flow projections were carried out for both the current electricity generation scenario and the proposed biomethane production scenario. The analysis considered both the standalone evaluation of the new project and the incremental analysis relative to the existing operation. The economic feasibility of the transition is assessed using Net Present Value (NPV) and Internal Rate of Return (IRR) indicators applied to the incremental cash flow, resulting in an NPV of R$ 91,875,107.43 and an IRR of 27%, demonstrating the attractiveness of the investment. It is concluded that biomethane production presents higher economic viability compared to electricity generation, representing a more advantageous alternative for the project. However, the results are dependent on the assumptions adopted, particularly regarding market prices and operational costs.

2026-05-12T00:00:00Z https://repositorio.ufu.br/handle/123456789/49142 2026-07-29T06:24:01Z 2026-07-24T00:00:00Z

Title: Modelagem e controle do conversor Dual Active Bridge (DAB) para aplicação em Sistemas de Armazenamento de Energia (SAEs) utilizando Hardware-in-the-Loop (HIL) Abstract: Recent years have proven fertile for research into renewable energy sources and the means to make them feasible. The growing demand for clean energy necessitates the creation and maintenance of new paradigms within the production and consumption of electrical energy. Consequently, new smaller-scale electrical system topologies have emerged, such as microgrids, which are closely linked to distributed power generation. The need for energy storage to ensure uninterrupted system operation has given rise to energy storage system (ESS) strategies, among which battery energy storage systems (BESS) are the most prominent. Therefore, this work presents the development of a 2.5 kW energy storage system capable of maintaining the bus regulated at 400 V during the absence of a primary source. Conversely, in the presence of a primary source, the ESS is capable of charging the battery using distinct stages of constant current at 13 A and constant voltage at 216 V. The bidirectional converter chosen was the Dual Active Bridge (DAB) due to features such as high gain, galvanic isolation, and the possibility of soft switching. The design, modeling, and control were performed using Single Phase Shift (SPS) modulation. The selection of charging and discharging moments is governed by an algorithm that monitors ESS parameters such as input voltage, output voltage, and output current, as well as the battery's State of Charge (SOC). The control algorithms were embedded in a Digital Signal Processor (DSP) for verification using the Controller Hardwarein-the-Loop (C-HIL) technique, and the power circuit is simulated in real-time via Typhoon HIL. Control response results are presented for all controllers, along with the results for charging and discharging mode transitions. Full charge and discharge cycles were performed, and their results are also presented, demonstrating the system's full operational capability.

2026-07-24T00:00:00Z https://repositorio.ufu.br/handle/123456789/49135 2026-07-29T06:23:49Z 2026-07-16T00:00:00Z

Title: Análise de distorções harmônicas em data centers: da medição em campo ao estudo de acesso à rede básica Abstract: The accelerated expansion of data centers, driven by the rise of Artificial Intelligence and the growing demand for digital services, has significantly increased electrical energy consumption and intensified concerns regarding the impacts of these facilities on Power Quality (PQ). Due to the non-linear nature of their loads, especially uninterruptible power supply (UPS) systems and frequency inverter-based cooling systems, these facilities act as potential sources of harmonic distortions, which can compromise grid performance at the point of connection. Given this scenario, the present work aims to analyze the harmonic distortions generated by data center operations and evaluate mitigation strategies in light of the access requirements for the Bulk Power System (Rede Básica). The adopted methodology articulates three levels of analysis: field measurements of a real medium-sized facility located in Uberlândia/MG, according to the PRODIST Module 8 guidelines; computational modeling of linear and nonlinear loads in the MATLAB/Simulink environment, based on the measured data; and the access study of a hyperscale complex to the 230 kV Bulk Power System, conducted in the HarmZs software in accordance with ONS Technical Note NT 009/2016 (rev. 03), representing the Internal Network with a Norton equivalent and the External Network using the Geometric Locus of harmonic admittances. Field measurements confirmed an emission profile compatible with 6- and 12-pulse rectifiers, with all PQ indicators within regulatory limits. In the access study, the original configuration showed a violation of the individual limit for the 11th harmonic order at the Point of Common Coupling (PCC). The insertion of a tuned passive filter for this order corrected the initial non-compliance but caused an amplification of the 3rd harmonic order due to a parallel resonance effect. The definitive solution was achieved by installing a second filter tuned to the 3rd order, empirically resized by increasing its power to 10% of the load power (1900 kVAr), which reduced the individual distortion to 0.56%, remaining below the 0.6% limit. It is concluded that the connection of data center complexes to the Bulk Power System is technically viable, provided it is accompanied by properly sized harmonic mitigation measures, and that the filter design must be conducted systemically, considering the global interaction between the facility's reactive elements and the equivalent grid impedance.

2026-07-16T00:00:00Z https://repositorio.ufu.br/handle/123456789/49118 2026-07-28T06:21:52Z 2026-07-10T00:00:00Z

Title: Development of a Model-in-the-Loop environment and design of an LQI attitude controller for open-source quadcopter Autopilots Abstract: A pesquisa sobre Veículos Aéreos Não Tripulados (VANTs) cresceu significativamente nos últimos anos e espera-se que continue a se expandir devido à grande variedade de projetos, aplicações, regulamentações e requisitos de desempenho dos veículos. Essas diferenças influenciam tanto a modelagem dinâmica das aeronaves quanto as estratégias de controle. Ao mesmo tempo, o rápido crescimento do mercado comercial de VANTs, que abrange desde drones de consumo até sistemas militares, aumentou a demanda pela integração de sensores, atuadores, unidades de processamento e cargas úteis avançadas, criando inúmeros desafios para pesquisa e desenvolvimento tanto na academia quanto na indústria. Embora as técnicas modernas de controle para quadricópteros sejam amplamente estudadas e tenham demonstrado implementações bem-sucedidas, os autopilotos de código aberto e os fabricantes comerciais de UAVs ainda dependem predominantemente de arquiteturas de controle Proporcional-Integral-Derivativo (PID). Essa persistência é impulsionada principalmente pela necessidade de retrocompatibilidade, limitações de hardware, suporte a múltiplas plataformas de UAVs e pela priorização da confiabilidade e extensibilidade do software em detrimento da reformulação do sistema de controle. Embora alguns estudos acadêmicos tenham implementado controladores avançados, estes são frequentemente executados em computadores auxiliares, em vez de serem incorporados diretamente à controladora de voo. Consequentemente, ainda existe uma lacuna na literatura em relação às implementações de abordagens de controle modernas em firmwares de controle de voo de código aberto, o que motiva esforços para transferir conceitos de controle acadêmicos para esses sistemas autônomos \textit{open-source}. Este trabalho, nesse contexto, apresenta um modelo dinâmico de um UAV do tipo quadricóptero que busca representar satisfatoriamente o uso da aeronave na maioria dos casos de aplicação. Além disso, antes de propor uma nova estratégia de controle, realiza-se também um estudo para analisar a estrutura de controle existente no maior piloto automático de código aberto: o Ardupilot. Com uma base sólida simulada utilizando um Model-in-the-Loop (MITL), a pesquisa alcança o potencial de comparar e analisar a viabilidade prática de diferentes estratégias de controle com o padrão já estabelecido. Portanto, com base no modelo desenvolvido, uma arquitetura de Controle Ótimo foi projetada para substituir a estrutura de controle original do autopiloto. Para ampliar o envelope de voo, o controlador ótimo linear foi associado a uma técnica de escalonamento de ganhos. Inicialmente, esse controlador foi projetado apenas para o malha de controle de atitude. A estratégia desenvolvida permitiu o rastreamento de trajetória com desempenho semelhante à arquitetura existente, com esforço de controle mínimo. Para seleções padrão da matriz de ganho, utilizando erros máximos conservadores conforme a Regra de Bryson, o ajuste do controle ótimo Linear-Quadrático-Integral (LQI) aumentou o Erro Integral Absoluto (IAE) em 5,76% em comparação com o PID original. No entanto, o controlador ótimo reduziu a Integral do Quadrado da Entrada (ISU) em 0,1% e a Variação Total (TV) em 50,45%.

2026-07-10T00:00:00Z