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Publicações

Publicações por CPES

2025

Data-Driven Charging Strategies to Mitigate EV Battery Degradation

Autores
Carvalhosa, S; Ferreira, JR; Araújo, RE;

Publicação
IEEE ACCESS

Abstract
Battery degradation remains a major challenge in electric vehicle (EV) adoption, directly affecting long-term performance, cost, and user satisfaction. This paper proposes a data-driven charging strategy that reduces battery wear while meeting the user's daily range needs. By integrating manufacturer guidelines, battery aging models, and thermal dynamics, the proposed optimization algorithm dynamically adjusts the charging current and timing to minimize stressors, such as high temperatures and prolonged high state of charge (SoC). The methodology is responsive to user inputs such as departure time and required driving range, enabling personalized charging behavior. Simulation results show that this approach can reduce battery degradation by up to 2.7% over a 30-day period compared to conventional charging habits, without compromising usability. The framework is designed for integration into Battery Management Systems (BMS), with applications for both private EV users and fleet operators. We address EV battery aging driven by high core temperature and prolonged high state of charge (SoC) during overnight/home charging. Given a user-specified departure time and required driving range, we schedule charging power over time to minimize predicted degradation exposure while still meeting the range requirement. The scheduler optimizes charging timing/current under SoC dynamics, thermal constraints, and charger/ BMS limits.

2025

Comparative Evaluation of the Performance of Vegetable Insulating Oils in Power Transformers Against the Lightning Impulse Voltage

Autores
Antonio Fernando Martins Cardoso; Mateus Martins Laranjeira; Bernardo Marques Amaral Silva; José Rui da Rocha Pinto Ferreira; Marcus Vinicius Alves Nunes;

Publicação
2025 16th IEEE International Conference on Industry Applications (INDUSCON)

Abstract

2025

Performance Evaluation of a Synthetic Ester-Based Insulating Fluid for Power Transformers under Lightning Impulse Stress

Autores
Antonio Fernando Martins Cardoso; Mateus Martins Laranjeira; Matias Pinheiro Torres Fabricius; Bernardo Marques Amaral Silva; José Rui da Rocha Pinto Ferreira; Marcus Vinicius Alves Nunes;

Publicação
2025 International Symposium on Lightning Protection (XVIII SIPDA)

Abstract

2025

Location of grid forming converters when dealing with multi-class stability problems

Autores
Fernandes, F; Lopes, JP; Moreira, C;

Publicação
IET GENERATION TRANSMISSION & DISTRIBUTION

Abstract
This work proposes an innovative methodology for the optimal placement of grid-forming converters (GFM) in converter-dominated grids while accounting for multiple stability classes. A heuristic-based methodology is proposed to solve an optimisation problem whose objective function encompasses up to 4 stability indices obtained through the simulation of a shortlist of disturbances. The proposed methodology was employed in a modified version of the 39-bus test system, using DigSILENT Power Factory as the simulation engine. First, the GFM placement problem is solved individually for the different stability classes to highlight the underlying physical phenomena that explain the optimality of the solutions and evidence the need for a multi-class approach. Second, a multi-class approach that combines the different stability indices through linear scalarisation (weights), using the normalised distance of each index to its limit as a way to define its importance, is adopted. For all the proposed fitness function formulations, the method successfully converged to a balanced solution among the various stability classes, thereby enhancing overall system stability.

2025

Frequency support from PEM hydrogen electrolysers using Power-Hardware-in-the-Loop validation

Autores
Elhawash, AM; Araújo, RE; Lopes, JAP;

Publicação
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

Abstract
Maintaining frequency stability is one of the biggest challenges facing future power systems, due to the increasing penetration levels of inverter-based renewable resources. This investigation experimentally validates the frequency provision capabilities of a real Polymer Electrolyte Membrane (PEM) hydrogen electrolyser (HE) using a power hardware-in-the-loop (PHIL) setup. The PHIL consists of a custom 3-level interleaved buck converter and a hardware platform for real-time control of the converter and conducting grid simulation, associated with the modelling of the future Iberian Peninsula (IP) and Continental Europe (CE) systems. The investigation had the aim of validating earlier simulation work and testing new responses from the electrolyser when providing different frequency services at different provision volumes. The experimental results corroborate earlier simulation results and capture extra electrolyser dynamics as the double-layer capacitance effect, which was absent in the simulations. Frequency Containment Reserve (FCR) and Fast Frequency Response (FFR) were provided successfully from the HE at different provision percentages, enhancing the nadir and the rate of change of frequency (RoCoF) in the power system when facing a large disturbance compared to conventional support only. The results verify that HE can surely contribute to frequency services, paving the way for future grid support studies beyond simulations.

2025

Evolving Symbolic Model for Dynamic Security Assessment in Power Systems

Autores
Fernandes, FS; Bessa, RJ; Lopes, JP;

Publicação
JOURNAL OF MODERN POWER SYSTEMS AND CLEAN ENERGY

Abstract
In a high-risk sector, such as power system, transparency and interpretability are key principles for effectively deploying artificial intelligence (AI) in control rooms. Therefore, this paper proposes a novel methodology, the evolving symbolic model (ESM), which is dedicated to generating highly interpretable data-driven models for dynamic security assessment (DSA), namely in system security classification (SC) and the definition of preventive control actions. The ESM uses simulated annealing for a data-driven evolution of a symbolic model template, enabling different cooperative learning schemes between humans and AI. The Madeira Island power system is used to validate the application of the ESM for DSA. The results show that the ESM has a classification accuracy comparable to pruned decision trees (DTs) while boasting higher global inter-pretability. Moreover, the ESM outperforms an operator-defined expert system and an artificial neural network in defining preventive control actions.

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