https://repositorio.ufu.br/handle/123456789/5464 2026-08-25T19:13:16Z 2026-08-25T19:13:16Z https://repositorio.ufu.br/handle/123456789/49547 2026-08-15T06:27:48Z 2026-07-17T00:00:00Z

Title: Implementação e avaliação experimental de sensores para detecção de descargas parciais Abstract: Partial discharges are an important indicator of the degradation of insulation systems in medium and high voltage electrical equipment, and are widely used for diagnosis and monitoring of the operational condition of these assets. In this context, this dissertation presents the implementation and experimental evaluation of sensors for the detection of partial discharges in insulated cables, developed from commercially accessible materials and additive manufacturing techniques. The objective of this study was to develop and experimentally characterize two electromagnetic sensor architectures, called Helical Antenna Sensor (HAS) and HFCT Relative Signature Sensor (HRSS), in addition to investigating the influence of physical, geometric and constructive parameters on the sensitivity of these devices. For this, design, manufacturing, experimental calibration and laboratory tests were carried out on insulated cables containing partial discharges. The performance of the prototypes was compared to that of a commercial HFCT sensor used as a reference. The results showed that both architectures were able to detect signals associated with partial discharges and reproduce patterns compatible with the investigated phenomena. It was found that changes in the construction parameters directly influence the sensitivity and response of the sensors.

2026-07-17T00:00:00Z https://repositorio.ufu.br/handle/123456789/49504 2026-08-17T12:32:21Z 2026-07-13T00:00:00Z

Title: Análise e controle de um sistema fotovoltaico conectado à rede elétrica com mitigação de harmônicas e armazenamento de energia Abstract: This work presents the analysis and control of a single-phase grid-connected photovoltaic system with integrated energy storage and harmonic distortion mitigation. The proposed system consists of a photovoltaic array connected to the direct current (DC) bus through a DC–DC Boost converter, an energy storage system based on batteries associated with a bidirectional Buck–Boost converter, and a Full-Bridge DC–AC inverter responsible for interfacing with the electrical grid. As a strategy to improve power quality, different passive filter topologies, namely L, LC, and LCL, were investigated and compared regarding their effectiveness in reducing harmonic distortions produced by the inverter. The adopted methodology was based on mathematical modeling, controller design, and computational simulation using PSIM software under different operating conditions to evaluate electrical performance, DC bus regulation, and power quality indices. The impacts of filter insertion on the injected current waveform and on the overall system performance were analyzed. The results demonstrated that all evaluated topologies contributed to reducing the Total Harmonic Distortion of current (THDi), achieving values of 3.77% for the L filter, 2.20% for the LC filter, and 1.94% for the LCL filter, highlighting the superior performance of the latter configuration. Additionally, the system achieved a power factor of up to 0.9999 and maintained the DC bus voltage regulated at 400 V, indicating satisfactory control performance and proper integration among photovoltaic generation, energy storage, and grid connection. It is concluded that the combined use of control techniques and passive filtering contributes to improving power quality and enhancing the operational performance of grid-connected photovoltaic systems.

2026-07-13T00:00:00Z 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