https://tede.unioeste.br/handle/tede/550 2026-09-12T18:34:41Z 2026-09-12T18:34:41Z Mattje, Juliana Lima https://tede.unioeste.br/handle/tede/8644 2026-09-09T13:19:19Z 2026-04-28T00:00:00Z

Title: Steady-State Thermal-Fluid Modeling of Station-Class Porcelain and Polymeric-Housed Surg Arresters with Internal Air Gap Autor: Mattje, Juliana Lima Primeiro orientador: Franco, Edgar Manuel Carreno Abstract: Este trabalho apresenta o desenvolvimento de modelos numéricos termo-fluidodinâmicos para para-raios com invólucro de porcelana de 228 kV e com invólucro polimérico de 240 kV, sob condições de operação em regime permanente. A abordagem eletrotérmica acoplada proposta permite uma representação detalhada do comportamento térmico do equipamento, ao considerar a distribuição não uniforme das perdas elétricas e a convecção natural nos domínios de ar interno e externo. Diferentemente de estudos anteriores que se baseiam em tratamentos simplificados da convecção natural, utilizando coeficientes médios de transferência de calor ou correlações empíricas, o presente trabalho adota uma formulação termo-fluidodinâmica completa, na qual as equações de conservação de massa, momento e energia são resolvidas pelo Método dos Volumes Finitos. Além disso, a geração de calor nos blocos de varistor de óxido de zinco (ZnO) é obtida a partir de um modelo elétrico, resultando em uma distribuição espacial fisicamente consistente de fontes volumétricas de calor. O modelo desenvolvido permite a predição de campos térmicos internos não acessíveis por técnicas experimentais e fornece uma ferramenta complementar à termografia infravermelha para o monitoramento de condição e avaliação de desempenho de para-raios. Adicionalmente, os coeficientes equivalentes de transferência de calor por convecção obtidos por meio das simulações podem auxiliar no aprimoramento de modelos térmicos simplificados. Por fim, a metodologia pode ser estendida para cenários operacionais mais complexos, incluindo a presença de defeitos internos e efeitos de instalação em transformadores. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Dissertação

2026-04-28T00:00:00Z Gomes, Guilherme Bachega https://tede.unioeste.br/handle/tede/8468 2026-06-17T13:50:31Z 2026-03-06T00:00:00Z

Title: Recomendação de quantificadores utilizando meta-aprendizado Autor: Gomes, Guilherme Bachega Primeiro orientador: Maletzke, André Gustavo Abstract: Metalearning based recommender systems have become an effective approach for the automatic selection of algorithms in machine learning tasks. This approach has been successfully employed in several studies to build recommenders across different domains. In the literature, there are works that investigate the recommendation of classifiers, hyperparameter configurations, and feature selection algorithms. Although a wide range of recommendation approaches has been proposed for classification problems, there is a lack of work in the context of quantification. Recently, quantification has attracted increasing interest in the machine learning community. Unlike classification, whose goal is to assign labels to unlabeled instances, quantification aims to estimate the class distribution in an unlabeled dataset. Several quantification methods have been proposed over the last years and, as in classification, there is no quantifier that consistently outperforms the others across all scenarios. Moreover, the empirical evaluation of quantifiers is particularly costly, as it requires generating multiple test sets with controlled prevalences. In this setting, determining the best quantifier for a given dataset is critical, yet labor-intensive when based on trial-and-error strategies. To address this gap, this work proposes the first meta-learning architecture for quantifier recommendation. The architecture models the relationship between dataset characteristics and quantifier performance to recommend a ranking of the most suitable quantifiers, without requiring trial-and-error experimentation. To evaluate the architecture, two quantifier recommendation strategies are developed. Experimental results demonstrate its effectiveness: under the best strategy, the system places the best-performing quantifier at the top of the recommended ranking in 91 out of 100 evaluated datasets. In addition, the ranking is directly explored in quantification tasks. When applying only the top-ranked quantifier, the method achieves performance comparable to the state-of-the-art DyS quantifier across the 100 datasets. On more complex datasets, performance remains stable and comparable to the best quantifier. Finally, combining the top quantifiers in the recommended ranking yields performance comparable to the state of the art over all datasets and superior performance when considering only the more complex datasets. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Dissertação

2026-03-06T00:00:00Z Bender, Samuel Graff https://tede.unioeste.br/handle/tede/8290 2026-03-03T12:29:22Z 2025-10-10T00:00:00Z

Title: Influência de técnicas de sincronização de conversores na distorção harmônica de microrredes Autor: Bender, Samuel Graff Primeiro orientador: Almeida, Adriano Batista de Abstract: Microgrids (MGs) are smaller-scale power systems used to integrate distributed energy resources into the main electrical grid through power converters. To ensure safe and efficient operation of these systems, both in grid-connected and islanded modes, control strategies are essential for power sharing and maintaining voltage and frequency stability. In the context of converter control, synchronization techniques, such as Phase-Locked Loops (PLLs), are employed to estimate the grid frequency and phase, ensuring the converters are synchronized with the voltage signal at their point of connection. However, these control systems are vulnerable to power quality issues, mainly voltage imbalances and harmonic distortions in the voltage signals. The presence of converters and non-linear loads are some of the causes of harmonic distortions in MGs, negatively affecting the performance of synchronization techniques. Based on the hypothesis that synchronization techniques may affect the harmonic distortion of voltage and current signals, and given the scarcity of studies regarding this problem, the present work aims to fill this gap in the literature by evaluating the dynamic behavior of synchronization techniques and their impact on the harmonic distortion of MGs. Four synchronization techniques were selected based on the literature and implemented on Digital Signal Processors (DSPs). The techniques were subjected to two types of tests: the first involved applying known signals using the UNIOESTE MG Laboratory structure, where their dynamic performance was evaluated under events of frequency and phase variation, and harmonic distortion. The second type of test was conducted via simulations in PSIM software, in which the laboratory MG model was implemented. The simulations considered the connection of a non-linear load model at different operating points and under various converter combinations. The experimental results showed that synchronization techniques with advanced filtering capabilities have better dynamic performance, ensuring robustness against grid disturbances. In the simulations, it was concluded that there is no significant coupling between the chosen synchronization technique and the harmonic distortion of the electrical quantities in the evaluated scenarios. The main contribution of this work is the verification of the hypothesis in the MG context, in addition to the development of the laboratory MG structure and the detailed computational model for future studies. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Dissertação

2025-10-10T00:00:00Z Pereira, Eduardo Henrique https://tede.unioeste.br/handle/tede/8210 2026-02-23T14:41:29Z 2025-11-27T00:00:00Z

Title: Comparação de protótipo localizador de faltas com relés comerciais: um estudo para identificação de melhorias Autor: Pereira, Eduardo Henrique Primeiro orientador: Motter, Daniel Abstract: Fault location (FL) in transmission lines (TL) plays a strategic role in the operation of electric power systems, as it makes it possible to precisely identify the point of occurrence of disturbances and reduce system restoration time. In this way, accurate FL estimates contribute to efficient service restoration and optimize maintenance activities, thus increasing system reliability. With the objective of monitoring signals and recording disturbances at points of interest, Itaipu Parquetec, with the support of ITAIPU Binacional, developed a device that integrates the functionalities of a Digital Fault Recorder (DFR) and a Phasor Measurement Unit (PMU), resulting in the Disturbance Recorder and Phasor Measurement Unit (RPMF), with its latest update being the addition of an LF module for LTs. Considering the need to test and enhance these updates, this work presents a comparative evaluation of the RPMF’s LF prototype with commercial LF estimators, in order to assess the technological compatibility between the products, as well as to verify whether the proposed multi-method can be applied to more critical LTs without the need for flexibility. To achieve this, real-time simulations were carried out using a Hardware-inthe-loop configuration, in which the RPMF and two intelligent electronic devices (IEDs) were connected in parallel to amplifiers controlled by a Real-Time Digital Simulator (RTDS). The LTused as a model in the tests is part of the Paraguayan power system, selected due to ITAIPU’s interest and aiming for future applications of the LF prototype at the location. In addition to the comparison with the commercial IEDs, the performance of the main LF methods present in the RPMF algorithm was also evaluated, namely: (i) Impedance Method, (ii) Reactance Method, (iii) Simple Takagi, (iv) Negative-Sequence Polarized Takagi, and (v) Zero-Sequence Polarized Takagi. A series of tests was conducted simulating various fault scenarios, including variations in fault type, resistance, incidence angle, and distance to the fault point. The analysis of the results allowed for a comparison between the methods implemented in the RPMF and the other evaluated equipment. The results obtained demonstrate that the RPMF presents satisfactory performance, comparable to the commercial solutions analyzed, and stands out in various scenarios. Furthermore, the analysis of the RPMF methods evidenced potential for multimethod improvement, revealing the possibility of recommendations for strategic adjustments that would increase its accuracy in more critical LTs. Thus, the study reinforces the viability of the RPMF as a promising national solution for LF, distinguishing itself by its performance and flexibility for adaptation to different conditions, while also indicating paths for future developments. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Dissertação

2025-11-27T00:00:00Z