Examinando por Autor "Rodriguez, J."
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Ítem An Overview of Microgrids Challenges in the Mining Industry(Institute of Electrical and Electronics Engineers Inc., 2020) Gomez, J.; Rodriguez, J.; Garcia, C.; Tarisciotti, L.; Flores-Bahamonde, F.; Pereda, J.; Nunez, F.; Cipriano, A.; Salas, J.The transition from fossil fuels to renewable energies as power sources in the heavy industries is one of the main climate change mitigation strategies. The carbon footprint in mining is related to its inherent extraction process, its high demand of electric power and water, and the use of diesel. However, considering its particular power requirements, the integration of microgrids throughout the whole control hierarchy of mining industry is an emergent topic. This paper provides an overview of the opportunities and challenges derived from the synergy between microgrids and the mining industry. Bidirectional and optimal power flow, as well as the integration of power quality have been identified as microgrid features that could potentially enhance mining processes. Recommendations pertaining to the technological transition and the improvement of energy issues in mining environments are also highlighted in this work.Ítem Model reference adaptive system with finite-set for encoderless control of PMSGs in micro-grid systems(MDPI AG, 2020-09) Abdelrahem, M.; Hackl, C.M.; Rodriguez, J.; Kennel, R.In micro-grid systems, wind turbines are essential power generation sources. The direct-driven surface-mounted permanent-magnet synchronous generators (SMPMSGs) in variable-speed wind generation systems (VS-WGSs) are promising due to their high efficiency/power density and the avoidance of using a gearbox, i.e., regular maintenance and noise are averted. Usually, the main goal of the control system for SMPMSGs is to extract the maximum available power from the wind turbine. To do so, the rotor position/speed of the SMPMSG must be known. Those signals are obtained by the help of an incremental encoder or speed transducer. However, the system reliability is remarkably reduced due to the high failure rate of these mechanical sensors. To avoid this problem, this paper presents a model reference adaptive system with finite-set (MRAS-FS) observer for encoderless control of SMPMSGs in VS-WGSs. The motif of the presented MRAS-FS observer is taken from the direct-model predictive control (DMPC) principle, where a certain number of rotor position angles are utilized to estimate the stator flux of the SMPMSG. Subsequently, a new optimization criterion (also called quality or cost function) is formulated to select the best rotor position angle based on minimizing the error between the estimated and reference value of the stator flux. Accordingly, the traditional fixed-gain proportional-integral regulator generally employed in the classical MRAS observers is not needed. The proposed MRAS-FS observer is validated experimentally, and its estimation response has been compared with the conventional MRAS observer under different conditions. In addition to that, the robustness of the MRAS-FS observer is tested at mismatches in the parameters of the SMPMSG. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Ítem Model-Free Predictive Current Control of a Voltage Source Inverter(Institute of Electrical and Electronics Engineers, 2020-11) Rodriguez, J.; Heydari, R.; Rafiee, Z.; Young, H.; Flores-Bahamonde, F.; Shahparasti, M.Conventional model predictive control (MPC) of power converter has been widely applied to power inverters achieving high performance, fast dynamic response, and accurate transient control of power converter. However, the MPC strategy is highly reliant on the accuracy of the inverter model used for the controlled system. Consequently, a parameter or model mismatch between the plant and the controller leads to a sub-optimal performance of MPC. In this paper, a new strategy called model-free predictive control (MF-PC) is proposed to improve such problems. The presented approach is based on a recursive least squares algorithm to identify the parameters of an auto-regressive with exogenous input (ARX) model. The proposed method provides an accurate prediction of the controlled variables without requiring detailed knowledge of the physical system. This new approach and is realized by employing a novel state space identification algorithm into the predictive control structure. The performance of the proposed model-free predictive control method is compared with conventional MPC. The simulation and experimental results show that the proposed method is totally robust against parameters and model changes compared with the conventional model based solutions.Ítem Simple Finite-Control-Set Model Predictive Control of Grid-Forming Inverters with LCL Filters(Institute of Electrical and Electronics Engineers Inc., 2020) Young, H.; Marin, V.; Pesce, C.; Rodriguez, J.Grid-forming inverters (GFI) play an important role as power interfaces for distributed generation units in islanded microgrids, where inductive-capacitive-inductive (LCL) output filters are commonly employed to mitigate the harmonics injected by voltage-source inverters. Due to advantages such as fast dynamic response and straightforward handling of constraints, Finite-control-set model predictive control (FCS-MPC) has become an attractive option for voltage control in GFI systems. However, conventional FCS-MPC algorithms with short prediction horizon have performance limitations in the tracking of ac references in systems with high-order dynamics, such as LCL-filtered GFIs. On the other hand, predictive algorithms with extended prediction horizons suffer from an increased computational burden. This paper proposes a new FCS-MPC algorithm to accurately control the capacitor voltage in an LCL-filtered GFI, using a discrete-time prediction model to dynamically compute the reference for a FCS-MPC inverter-side current controller. The main advantages of the proposed method are its simple implementation without requiring the tuning of weighting factors in its cost function; and its short prediction horizon, which maintains a reduced computational cost. Moreover, active resonance damping elements such as digital filters or ad hoc feedback loops to deal with the LCL filter resonance are not required. Simulation tests and experimental results in a laboratory-scale setup confirm the effectiveness of the proposed control algorithm, yielding lower distortion of output voltage waveforms and increased robustness to modeling errors compared with the conventional FCS-MPC approach.Ítem Uso de multiinyector para electro-hilado de fibras cerámicas en aplicaciones energéticas(Elsevier, 2019) Campana, R.; Sevilla, G.; Herradón, C.; Larrañaga, A.; Rodriguez, J.En este trabajo se propone el empleo de la técnica de electro-hilado para la síntesis de fibras cerámicas que puedan ser empleadas como constituyentes de electrodos de pilas de combustible de óxido sólido. Concretamente se ha demostrado el aumento en la capacidad de producción de fibras cerámicas (en un orden de magnitud) gracias a la sustitución de un inyector simple por uno múltiple (provisto de 10 agujas). Además, los diámetros, longitudes, tamaños de cristal y área superficial de las fibras obtenidas indican que estas podrían ser empleadas para fabricar electrodos con una microestructura altamente porosa, fácilmente infiltrable y donde se maximice la región donde tiene lugar la reacción de reducción de oxígeno y el transporte de gases y cargas.