Power transformers thermal modeling using an Enhanced Set-Membership Multivariable Gaussian Evolving Fuzzy System

Knowledge of temperature distribution in power transformers is essential for the management of electrical distribution systems. Monitoring the hot-spot temperature of a power transformer can extend its lifetime. In this work, we present two new models based on Set-Membership filtering: the Set-Membership evolving Multivariable Gaussian and the Enhanced Set-Membership evolving Multivariable Gaussian. Both approaches are acting by adjusting the learning rate in the evolving fuzzy modeling system. To evaluate its performance were applied synthetic data sets, as benchmarks, and data for thermal modeling of real power transformers, under two load conditions: with and without an overload condition. The obtained results are compared with the performance of the original evolving Multivariable Gaussian and with other classical models suggested in the literature. Both proposed models obtained lower errors and presenting a competitive number of rules, suggesting that the models are flexible and efficient approaches in these scenarios.O conhecimento da distribuição de temperatura em transformadores de potência é essencial para o gerenciamento de sistemas de distribuição elétrica. O monitoramento da temperatura do ponto quente de um transformador de energia pode estender sua vida útil. Neste trabalho, apresentamos dois novos modelos baseados na filtragem Set-Membership: o Set-Membership evolutivo Gaussiano Multivariado e o Enhanced Set-Membership evolutivo Gaussiano Multivariado. Ambas as abordagens agem ajustando a taxa de aprendizagem no sistema de modelagem fuzzy evolutivo. Para avaliar seu desempenho foram aplicados conjuntos de dados sintéticos, como benchmarks, e dados para modelagem térmica de transformadores de potência reais, sob duas condições de carga: com e sem sobrecarga. Os resultados obtidos são comparados com o desempenho do modelo evolutivo Gaussiano Multivariado original e com outros modelos clássicos sugeridos na literatura. Ambos os modelos propostos obtiveram erros menores e apresentam número competitivo de regras, sugerindo que os modelos são abordagens flexíveis e eficientes nestes cenários.PROQUALI (UFJF

Transformer NN-based behavioral modeling and predistortion for wideband pas

Abstract. This work investigates the suitability of transformer neural networks (NNs) for behavioral modeling and the predistortion of wideband power amplifiers. We propose an augmented real-valued time delay transformer NN (ARVTDTNN) model based on a transformer encoder that utilizes the multi-head attention mechanism. The inherent parallelized computation nature of transformers enables faster training and inference in the hardware implementation phase. Additionally, transformers have the potential to learn complex nonlinearities and long-term memory effects that will appear in future high-bandwidth power amplifiers. The experimental results based on 100 MHz LDMOS Doherty PA show that the ARVTDTNN model exhibits superior or comparable performance to the state-of-the-art models in terms of normalized mean square error (NMSE) and adjacent channel power ratio (ACPR). It improves the NMSE and ACPR up to −37.6 dB and −41.8 dB, respectively. Moreover, this approach can be considered as a generic framework to solve sequence-to-one regression problems with the transformer architecture

Predicting the Future

Due to the increased capabilities of microprocessors and the advent of graphics processing units (GPUs) in recent decades, the use of machine learning methodologies has become popular in many fields of science and technology. This fact, together with the availability of large amounts of information, has meant that machine learning and Big Data have an important presence in the field of Energy. This Special Issue entitled “Predicting the Future—Big Data and Machine Learning” is focused on applications of machine learning methodologies in the field of energy. Topics include but are not limited to the following: big data architectures of power supply systems, energy-saving and efficiency models, environmental effects of energy consumption, prediction of occupational health and safety outcomes in the energy industry, price forecast prediction of raw materials, and energy management of smart buildings

Spatial-Temporal Recurrent Graph Neural Networks for Fault Diagnostics in Power Distribution Systems

Fault diagnostics are extremely important to decide proper actions toward fault isolation and system restoration. The growing integration of inverter-based distributed energy resources imposes strong influences on fault detection using traditional overcurrent relays. This paper utilizes emerging graph learning techniques to build a new temporal recurrent graph neural network models for fault diagnostics. The temporal recurrent graph neural network structures can extract the spatial-temporal features from data of voltage measurement units installed at the critical buses. From these features, fault event detection, fault type/phase classification, and fault location are performed. Compared with previous works, the proposed temporal recurrent graph neural networks provide a better generalization for fault diagnostics. Moreover, the proposed scheme retrieves the voltage signals instead of current signals so that there is no need to install relays at all lines of the distribution system. Therefore, the proposed scheme is generalizable and not limited by the number of relays installed. The effectiveness of the proposed method is comprehensively evaluated on the Potsdam microgrid and IEEE 123-node system in comparison with other neural network structures

Advances in Batteries, Battery Modeling, Battery Management System, Battery Thermal Management, SOC, SOH, and Charge/Discharge Characteristics in EV Applications

The second-generation hybrid and Electric Vehicles are currently leading the paradigm shift in the automobile industry, replacing conventional diesel and gasoline-powered vehicles. The Battery Management System is crucial in these electric vehicles and also essential for renewable energy storage systems. This review paper focuses on batteries and addresses concerns, difficulties, and solutions associated with them. It explores key technologies of Battery Management System, including battery modeling, state estimation, and battery charging. A thorough analysis of numerous battery models, including electric, thermal, and electro-thermal models, is provided in the article. Additionally, it surveys battery state estimations for a charge and health. Furthermore, the different battery charging approaches and optimization methods are discussed. The Battery Management System performs a wide range of tasks, including as monitoring voltage and current, estimating charge and discharge, equalizing and protecting the battery, managing temperature conditions, and managing battery data. It also looks at various cell balancing circuit types, current and voltage stressors, control reliability, power loss, efficiency, as well as their advantages and disadvantages. The paper also discusses research gaps in battery management systems.publishedVersio