132 research outputs found
Rol de la electrónica de potencia en las energías renovables y la calidad de red
1. Estudio teórico del control no lineal en accionamientos eléctricos enfocados a la generación de energía eléctrica basados en fuentes de energías renovables.
2. Metodologías de control no lineal aplicados a convertidores de potenciaCONACYT - Consejo Nacional de Ciencia y TecnologíaPROCIENCI
Finite-fixed switching predictive control technique for a 7-level cascaded H-bridge multilevel active power filter. A comparative study.
This paper presents a finite-fixed predictive control technique applied to the three-wire cascade H-bridge multilevel converters for active power filter applications. The focus of this paper is to examine the impacts of the use of optimum modulation techniques combined with predictive current control in order to increase the control performance in terms of reactive power compensation and total harmonic distortion.CONACYT – Consejo Nacional de Ciencia y Tecnologí
Asymmetric multilevel topology for photovoltaic energy injection to microgrids
The massive penetration of renewable energy sources in the utility grid has emerged as the solution to obtain clean energy in modern electric systems, which are gradually replacing their generators that produce CO2 emissions to achieve a sustainable growing. Power electronics is quite relevant in the deep penetration of renewable energy, because the use of such equipment is mandatory to integrate these new resources with the existing facilities. In order to reach higher power ranges, multilevel topologies are the state-of-the-art solution, due to the limited rating of the actual semiconductor devices. Furthermore, latest trends show that asymmetric multilevel configurations are an attractive technology to connect directly the power converters to the grid. This paper analyze the photovoltaic energy injection to microgrids using a hybrid approach that mixes the existing topologies: string, multistring and central inverter to implement an asymmetric structure that generate highly sinusoidal resulting waveforms. This document includes a simple analysis of the proposed configuration and highlights the advantages of using an asymmetric converter, supported with stationary and dynamic simulated results
Research in power electronics and control
Fault-tolerance is one of the most interesting feature of wind energy conversion systems (WECS). The ability to maintain operation even after an open-phase fault, allows for the system operators to maintain energy production, providing tangible economic benefits.CONACYT – Consejo Nacional de Ciencia y Tecnologí
Predictive-fixed switching frequency technique for six-phase wind energy conversion systems
This paper presents a speed control with an enhanced predictive current control technique with fixed switching frequency applied to the six-phase wind energy conversion systems. Simulation results show the efficiency of the proposed technique, demonstrating that it is a viable alternative to conventional predictive controllers.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI
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Scene memory and spatial inhibition in visual search
Abstract: Any object-oriented action requires that the object be first brought into the attentional foreground, often through visual search. Outside the laboratory, this would always take place in the presence of a scene representation acquired from ongoing visual exploration. The interaction of scene memory with visual search is still not completely understood. Feature integration theory (FIT) has shaped both research on visual search, emphasizing the scaling of search times with set size when searches entail feature conjunctions, and research on visual working memory through the change detection paradigm. Despite its neural motivation, there is no consistently neural process account of FIT in both its dimensions. We propose such an account that integrates (1) visual exploration and the building of scene memory, (2) the attentional detection of visual transients and the extraction of search cues, and (3) visual search itself. The model uses dynamic field theory in which networks of neural dynamic populations supporting stable activation states are coupled to generate sequences of processing steps. The neural architecture accounts for basic findings in visual search and proposes a concrete mechanism for the integration of working memory into the search process. In a behavioral experiment, we address the long-standing question of whether both the overall speed and the efficiency of visual search can be improved by scene memory. We find both effects and provide model fits of the behavioral results. In a second experiment, we show that the increase in efficiency is fragile, and trace that fragility to the resetting of spatial working memory
A review of existing evaluation methods for point clouds quality
This paper analyzes the existing evaluation methods for the point cloud quality and a new discussion regarding their applicability to aerial photographs is opened. Some of these methods are chosen based on practical issues and applied to a pair of reconstructions. The principal conclusion is that objective methods are the most interesting in photogrammetry applications, particularly the comparison between two point clouds.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI
Attitude tracking of a tri-rotor uav based on robust sliding mode with time delay estimation
The paper presents a robust sliding mode with time delay estimation method for controlling the attitude of a tri-rotor unmanned aerial vehicle (UAV) in presence of uncertainties and disturbances. The proposed control algorithm allows high accuracy tracking since a good disturbance estimation is provided using time delay estimation method and allows chattering reduction. The stability analysis of the closedloop system is presented using the theory of Lyapunov. Finally, two numerical simulations are presented in the presence of disturbances to show the effectiveness of the proposed nonlinear control scheme.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI
Modulated model based predictive control with switcher of redundant states for a three-phase cascade H-bridge multilevel STATCOM
Due to problems caused by variable switching frequency a modulated model based predictive control was proposed for different topologies and their applications. However, for cascade H-bridge multilevel converters, there is another problem, the imbalance in the dc-link voltages. This paper proposes extend the modulated model based predictive control to a cascade H-bridge 7-level STATCOM, further including a switcher of redundant states to solve the imbalance voltage issue. Simulation results show improvements in terms of mean squared error, total harmonic distortion and balance voltages in the dc-links.CONACYT – Consejo Nacional de Ciencia y Tecnologí
Nonlinear backstepping with time delay estimation for six-phase induction machine
In this paper, a robust nonlinear stator currents controller based on a known nonlinear technique is proposed for a six-phase induction machine. First of all, a proportional-integral regulator is used in an outer loop to control the speed. Secondly, the inner loop based on a nonlinear method that combines the nonlinear backstepping control scheme with the time delay estimation consists of controlling the stator currents. The chosen time delay estimation method can approximate the unmeasurable rotor current while the nonlinear backstepping can achieve good tracking performances. The stability analysis of the current closed-loop error dynamics is provided based on a recursive Lyapunov function. Numerical simulations have been conducted to demonstrate the efficiency and the performance of the developed nonlinear control method for the asymmetrical six-phase induction machine.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI
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