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Publicações

Publicações por CPES

2025

Multiobjective energy management of multi-source offshore parks assisted with hybrid battery and hydrogen/fuel-cell energy storage systems

Autores
Kazemi-Robati, E; Varotto, S; Silva, B; Temiz, I;

Publicação
APPLIED ENERGY

Abstract
With the recent advancements in the development of hybrid offshore parks and the expected large-scale implementation of them in the near future, it becomes paramount to investigate proper energy management strategies to improve the integrability of these parks into the power systems. This paper addresses a multiobjective energy management approach using a hybrid energy storage system comprising batteries and hydrogen/fuel-cell systems applied to multi-source wind-wave and wind-solar offshore parks to maximize the delivered energy while minimizing the variations of the power output. To find the solution of the optimization problem defined for energy management, a strategy is proposed based on the examination of a set of weighting factors to form the Pareto front while the problem associated with each of them is assessed in a mixed-integer linear programming framework. Subsequently, fuzzy decision making is applied to select the final solution among the ones existing in the Pareto front. The studies are implemented in different locations considering scenarios for electrical system limitation and the place of the storage units. According to the results, applying the proposed multiobjective framework successfully addresses the enhancement of energy delivery and the decrease in power output fluctuations in the hybrid offshore parks across all scenarios of electrical system limitation and combinational storage locations. Based on the results, in addition to the increase in delivered energy, a decrease in power variations by around 40 % up to over 80 % is observed in the studied cases.

2025

Speed Control of Switched Reluctance Motor with Torque Ripple Reduction Based on Super-Twisting Sliding Mode Control

Autores
Touati, Z; Araújo, RE;

Publicação
IFAC PAPERSONLINE

Abstract
In this paper, a robust nonlinear Super-Twisting Sliding Mode Controller (STSMC) is proposed to minimize torque ripple in Switched Reluctance Motor (SRM) drive systems, thereby reducing acoustic noise and vibration. To optimize torque ripple, the firing angles (theta(on) and theta(off)) are dynamically adjusted based on the instantaneous torque and speed error. To demonstrate its superiority, the performance of the STSMC is compared with conventional linear and Sliding Mode Control (SMC) regulators. The results confirm the robustness and effectiveness of the proposed controller. The torque ripple with PSO-optimized firing angles and STSMC is reduced by around 50% compared to conventional fixed switching angles. Copyright (c) 2025 The Authors. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)

2025

A New Design for an Electrolyzer Power Converter Architecture Capable of Fault Ride Through

Autores
Elhawash, M; Araújo, RE; Lopes, A;

Publicação
2025 IEEE Kiel PowerTech

Abstract
This paper presents a new power chain and its control scheme that provides highly flexible low voltage ride through (LVRT) capabilities for power converters that feed the stack of Polymer Electrolyte Membrane (PEM) hydrogen electrolyzers. It introduces an intermediate power stage with a new adaptive feedforward controller, that isolates the electrolyzer stack from grid-side disturbances. An RMS model of the whole solution is developed and validated. The system was developed in MATLAB/SIMULINK and PLECS environments. Furthermore, the system was tested in DC and AC grids by subjecting it to a fault reducing the input voltage magnitude down to 0.2 pu. The system demonstrated its ability to ride through the fault whilst maintaining the power set-points and supply quality at the electrolyzer stack connection point. © 2025 Elsevier B.V., All rights reserved.

2025

Towards a digital model for emulation of an electrolyzer in real-time: An initial study

Autores
Joao, MA; Araújo, RE;

Publicação
2025 9TH INTERNATIONAL YOUNG ENGINEERS FORUM ON ELECTRICAL AND COMPUTER ENGINEERING, YEF-ECE

Abstract
The objective of this paper is to delineate the ongoing doctoral research work that is focused on the development of a digital model intended to emulate the real-time operation of an electrolyzer that is powered by a DC/DC converter. The digital model of the converter and the proton exchange membrane (PEM) electrolyzer (EL) is presented, and it is based on an electrical equivalent model. A primary contribution of this study is the analysis of the errors resulting from the discretization process. Furthermore, the implementation and development of the digital model requires a comprehensive study of the errors and key affecting factors. Additionally, the formulation of a mechanism to reduce these errors is essential for advancing this topic. Preliminary results obtained using the digital emulator developed demonstrated its capacity to reproduce the voltage and current response applied to the electrolyzer with a reduced error compared to the continuous-time model.

2025

A Nonlinear Control Allocation Strategy for Dual Half Bridge Power Converters

Autores
de Castro, R; Araujo, RE; Brembeck, J;

Publicação
IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING

Abstract
This work focuses on designing nonlinear control algorithms for dual half-bridge converters (DHBs). We propose a two-layer controller to regulate the current and voltage of the DHB. The first layer utilizes a change in the control variable to obtain a quasi-linear representation of the DHB, allowing for the application of simple linear controllers to regulate current and power flow. The second layer employs a nonlinear control allocation algorithm to select control actions that fulfill (pseudo) power setpoints specified by the first control layer; it also minimizes peak-to-peak currents in the DHB and enforces voltage balance constraints. We apply the DHB and this new control strategy to manage power flow in a hybrid energy storage system comprising of a battery and supercapacitors. Numerical simulation results demonstrate that, in comparison with state-of-the-art approaches, our control algorithm is capable of maintaining good transient behavior over a wide operating range, while reducing peak-to-peak current by up to 80%.

2025

Comparative analysis of active rectifiers for hydrogen electrolyzer applications

Autores
Délcio Pedro; Rui Esteves Araújo;

Publicação
2025 IEEE Vehicle Power and Propulsion Conference (VPPC)

Abstract

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