Analysis and Design Guidelines for Current Control Loops of Grid-Connected Converters Based on Mathematical Models

Having a method for analyzing and designing regulators of controls that contain many current loops such as active filters is not a trivial task. There can be many parameters of regulators and filters that must be carefully selected in order to fulfill certain desired requirements. For instance, these can be stability, dynamic response, robustness under uncertainty of parameters, and rejection capability to switching harmonics. Hence, this paper provides general analysis guidelines for designing current control loops by using mathematical models in an αβ reference frame. Then, by using the proposed modeling tool, a multi-objective tuning algorithm is proposed that helps obtain all the control loops’ regulator and filter parameters, meeting all the desired requirements. Thus, the proposed analysis and design methodology is illustrated by applying it to three different controls conceived in a dq rotating reference frame with PI (Proportional Integral) regulators. The first control presents two current loops (simple dq current control), the second control uses four current loops (dual vector control, for unbalanced loads), while the third control presents eight current loops (active filter controlling current harmonics). Several experimental and simulation results show the effectiveness and usefulness of the proposed method. Since the mathematical model employed is in the αβ reference frame, it can also be easily applied to controls conceived in a αβ reference frame using resonant regulators, providing also a common comparative framework

Early stages of LDL oxidation: apolipoprotein B structural changes monitored by infrared spectroscopy.

Changes in the conformation of apoliprotein B-100 in the early stages of copper-mediated low density lipoprotein oxidation have been monitored by infrared spectroscopy. During the lag phase no variation in structure is observed, indicating that copper binding to the protein does not significantly affect its structure. In the propagation phase, while hydroperoxides are formed but the protein is not modified, no changes in secondary structure are observed, but the thermal profile of the band corresponding to alpha-helix is displaced in frequency, indicating changes in tertiary structure associated with this conformation but not with beta-sheet components. When aldehyde formation starts, a decrease of approximately 3% in the area of bands corresponding to alpha-helix and beta-sheet is produced, concomitantly with an increase in beta-turns and unordered structure. The two bands corresponding to beta-turns vary as well under these conditions, indicating changes in these structures. Also at this stage the thermal profile shows variations in frequency for the bands corresponding to both alpha-helix and beta-sheet.The results are consistent with the hypothesis that as soon as the polyunsaturated fatty acids from the particle core are modified, this change is reflected at the surface, in the alpha-helical components contacting the monolayer.Fil: Chehin, Rosana Nieves. Consejo Superior de Investigaciones Científicas; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad del País Vasco; EspañaFil: Rengel, David. Consejo Superior de Investigaciones Científicas; España. Universidad del País Vasco; EspañaFil: Milicua, José Carlos G.. Universidad del País Vasco; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Goñi, Félix M.. Universidad del País Vasco; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Arrondo JL. Consejo Superior de Investigaciones Científicas; España. Universidad del País Vasco; EspañaFil: Pifat, Greta. Rudjer Bošković Institute; Croaci

Electric Technology in Wind Turbines from a Dialectic Perspective

Wind turbines have been used by many groups of humans for many centu-ries. Wind turbines have allowed groups of humans to perform many different tasks in the past (grinding grain, pumping water, etc.). However, only a century and a half ago, they began to be used to convert the energy captured from wind into electric energy. Moreover, only approximately twenty-five years ago, we started to introduce on a massive scale the energy generated from wind turbines into the electric networks of most developed countries in the world for regular consumption. According to 2017 statistics, approximately 12 percent of the electric energy consumed in the EU is pro-duced by wind turbines. Despite the fact that wind turbines generally appear quite similar externally—i.e., a three-blade structure, a nacelle, a tower, etc.—if we care-fully examine the electric technology used within them, we find quite a wide range of technologies for energy conversion, which is a key issue in wind turbine technology. Hence, this paper adopts a dialectic perspective towards analyzing and understanding why several electric technologies coexist in wind turbine technology. We explain the specific factors that have influenced different wind turbine manufacturers to adopt dif-ferent electric technologies across the last twenty-five years. We show how their actions and the technological directions that have followed have been mutually codetermined, resulting in a technological evolution that has produced today’s wind turbine variety

Modelos Y Estilos De Resolución De Conflictos En El Marco De Una Cultura De La Paz Para Los Líderes De Las Unidades Habitacionales Del Municipio De Puebla, México

This paper focuses on the different theories on management and styles of conflict resolution in order to establish a culture of peace among the leaders of the housing units of the municipality of Puebla, Mexico. The literature was reviewed using keywords in different databases. The main findings suggest that there is a great diversity of models and styles of conflict resolution, as well as different instruments to evaluate them. However, its focus is fundamentally oriented to organizational reality, rather than to issues of a social nature. The model and style of conflict resolution that best explains the prevailing situation in housing units is the two-dimensional approach with four styles

Modelo estratégico que sustenta la importancia del currículum flexible en las IES

En el siguiente artículo se presenta un modelo basado en la planeación estratégica que aglutina una serie de elementos académicos, sociales y estratégicos que, en conjunto, buscan fortalecer la idea de crear currículum flexible en las Instituciones de Educación Superior –IES-. La metodología con la cual se realiza este estudio es cualitativa, y se sustenta en una investigación documentada y de corte transversal. Cabe resaltar, que este escrito se extrae de una tesis doctoral que presenta más de veinte propuestas que sustentan la importancia de establecer currículum flexible. Como resultado, aquí se muestra la propuesta a la que se llega a partir de todo el documento elaborado

Modelo estratégico que sustenta la importancia del currículum flexible en las IES

En el siguiente artículo se presenta un modelo basado en la planeación estratégica que aglutina una serie de elementos académicos, sociales y estratégicos que, en conjunto, buscan fortalecer la idea de crear currículum flexible en las Instituciones de Educación Superior –IES-. La metodología con la cual se realiza este estudio es cualitativa, y se sustenta en una investigación documentada y de corte transversal. Cabe resaltar, que este escrito se extrae de una tesis doctoral que presenta más de veinte propuestas que sustentan la importancia de establecer currículum flexible. Como resultado, aquí se muestra la propuesta a la que se llega a partir de todo el documento elaborado

Evaluación de pautas de diseño bioclimático aplicadas en edificios de vivienda en Uruguay (clima templado húmedo)

Este artículo presenta consumos de energía en viviendas obtenidos a partir de simulaciones computacionales para dos ciudades representativas del clima de Uruguay. El objetivo es evaluar las potencialidades de las estrategias de diseño que se utilizan frecuentemente en la construcción tradicional y sus posibles ajustes. Las estrategias que se presentan son: orientación, factor de huecos, protección solar y transmitancia térmica. En Salto la aplicación de las estrategias de diseño que tienen que ver con el control de la energía incidente (protecciones solares y/o factor de huecos) son determinantes en el consumo de energía total de la vivienda. En Montevideo y en Salto la colocación de aislante térmico tiene un peso relativo similar sobre el consumo de energía.This article presents energy consumption in dwellings obtained from computer simulations for two representative climate cities in Uruguay. The objective is to assess the potential of design strategies that are frequently used in traditional construction and their possible adjustments. The strategies presented are: solar orientation, hole factor, sun protection and thermal transmittance. In Salto implementing design strategies that have to do with control of the incident energy (solar protection and / or hole factor) are determinant of the total housing energy consumption. In Salto and Montevideo placement of thermal insulation has a similar relative influence in the energy consumption.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES