Smart Operation of Four-Quadrant Electric Vehicle Chargers in Distribution Grids

Many policies and programs adopted in the context of climate change mitigation and substitution of fossil fuels are contributing to the continuous development and growth of Electric Vehicles (EVs) in urban mobility systems, reaching 1.26 million units on the roads through the end of 2015. Even though the increasing number of EVs will create problems in distribution systems, which can be mitigated using smart charging strategies, there will also be economic opportunities for EV owners to provide services to the grid while their vehicle are parked and plugged in, a concept known as Vehicle-to-Grid (V2G). Most of the studies on V2G have concentrated on the provision of services such as frequency regulation or spinning reserves, which may reduce the battery life because of the required extra charging/discharging cycles, and little attention has been paid to the possibility of providing reactive power control services to the grid by using the ac/dc converter and the dc link capacitor available in most advanced chargers, a practice that does not compromise the vehicle battery life. These kinds of chargers, which are known as four-quadrant EV chargers due to the capability of being operated in all quadrants of the P-Q plane, can be used in distribution networks to improve the power factor and help regulate voltage, thus facilitating larger EV penetrations, as discussed in this thesis. In the first part of this thesis, a new average model of a single-phase, four-quadrant EV charger is developed. The steady-state and step responses of the proposed model for different P-Q requests, corresponding to the operation in the four quadrants of the P-Q plane, are used to validate its performance against a four-quadrant EV charger prototype. The model is shown to be useful for efficient time-domain simulations and studies that include a number of EV chargers, such as EV integration studies in Low-Voltage (LV) distribution networks. A practical case study is presented to demonstrate and test the performances of the four-quadrant charger and its model, investigating the voltage interactions of several chargers in an LV residential network during the provision of three vehicle-to-grid (V2G) strategies for active and reactive power. In the second part, a novel three-stage algorithm to coordinate the operation of four-quadrant EV chargers with other volt/var control devices in Medium-Voltage (MV) and LV distribution feeders is proposed. The first stage of the algorithm is operated on a day-ahead basis and defines the Load Tap Changer (LTC) and capacitor schedules while minimizing the peak load associated with EVs in the distribution system. The second and third stages update their operation every five minutes, to fairly allocate the aggregated and individual EV loads in the MV and LV feeders, respectively, while minimizing active power losses and voltage deviations. The proposed technique is applied to CIGRE's North-American MV and LV benchmark systems to demonstrate its ability to properly allocate EV loads, and improve distribution system performance in terms of losses and voltage profiles

Communicative interaction and organizational culture

This article is an approach to the concepts of Culture and organizational culture from different theoretical perspectives. Furthermore, it aims at establishing a relationship between the notions on communicative interaction and organizational culture, expounding two possible hermeneutic models in order to approach such an issue.El presente artículo es una aproximación a los conceptos de cultura y cultura organizacional desde distintas perspectivas teóricas. Igualmente, intenta una relación entre las nociones de interacción comunicativa y cultura organizacional, planteando dos posibles modelos hermenéuticos para abordar dicha problemática

Health insurance as a strategy for access: streamlined facts of the colombian health care reform

The Colombian reform to the health system (Law 100 of 1993) established, as strategy to facilitate the access, the universality of a health insurance that is acquired by means of the quotation in the contributive regime or by means of the gratuitous affiliation to the subsidized regime, in order to cover all the population with a unique plan of benefits that includes services in all levels of complexity. In this paper we intend to cover the main streamlined facts of the reform as far as coverage and access of the insurance, by means of logit models, the determinants of the enrollment and the access are considered, using data from the Living Standards Surveys of 1997 and 2003. It stands out that the coverage rose from 20% of the population in 1993 to 60% in 2003, although it seems very difficult to reach the universality; the structure and evolution of the coverage show that both regimes complement each other, while the contributive one has greater presence in the cities and among the population with formal employment, the subsidized one has greater weight among the rural population and in those with low levels of income; on the other hand, the insurance has advantages for the subsidized population, with a greater probability for use of the services, although the plan offers less benefits than the contributive one there are some barriers for the access.health insurance, access, enrollment affiliation, social security, Colombia

El logro académico y el efecto colegio en las pruebas Icfes en Antioquia

RESUMEN: Esta investigación muestra que, a través de un análisis del diseño institucional e implementación, el programa de bonos educativos Paces en Colombia, en el periodo 1992-1998, estuvo lejos de cumplir sus objetivos de corto y largo plazo. La no inclusión dentro del valor del bono del costo de oportunidad por los ingresos laborales perdidos, la escasa regulación y monitoreo de los colegios participantes, en especial de aquellos que surgieron a raíz del programa, son algunos de los factores que incidieron en sus resultados. Al final, se presentan algunas propuestas para mejorar el diseño de este tipo de programas que permitan alcanzar los objetivos planteados en cuanto a cobertura, calidad y equidad.ABSTRACT: This research show, through an analysis of the institutional design and the implementation of the program, that the program for educational aids Paces, in Colombia, in the 1992-1998 term, did not accomplish its short-term and long-term objectives. The fact that the opportunity cost for the lost revenues was not included in the value of the "bono" andthe poor control and monitoring of the intervening schools, particularly those that were created with the program, are some of the issues that had an effect on the results. At the end, we present some proposals for a better design of this type of programs that makes possible reaching the objectives proposed as to "covertures", quality, and equity

Evaluación del comportamiento en el largo plazo de un puente con elementos construidos con secciones con materiales compuestos

104 páginasThis paper analyzes the properties of a footbridge with a truss system made of composite materials and a slab of reinforced concrete at the time of completion and two years later after being exposed to environmental conditions. In order to study the evolution of the bridge and find the current stiffness, load and vibration tests were executed to the structure and then compared to the stiffness design hypotheses and test performed originally after the construction. The latest test results indicate that no significant deterioration occurred to the bridge properties during this period of exposure and use.El presente trabajo analiza las propiedades de un puente peatonal, con un sistema de vigas con materiales compuestos y losa en concreto reforzado, una vez construido y dos años después, expuesto a condiciones ambientales. Para estudiar la evolución del puente y encontrar la rigidez actual, se ejecutaron ensayos de carga y vibración sobre la estructura y se comparó dicha rigidez con las hipótesis de diseño y los ensayos realizados luego de la construcción. Los resultados de los últimos ensayos indican que no hubo un deterioro significativo en las propiedades del puente durante este periodo de exposición y uso.PregradoIngeniero(a) Civi

Determinación del efecto de la deficiencia de vitamina A sobre la homeostasis del hierro y su estado en modelo murino

122 páginasIron deficiency anemia (IDA) and vitamin A deficiency (VAD) belong to the micronutrient deficiencies defined by the WHO as worldwide concern. In Colombia, IDA prevalence for children from 1 to 4 years old is 14.8% and anemia is 24.7% for children from 6 to 59 months old, it is remarkable in a country where is mandatory to fortify wheat flour with iron since 1996. On the other hand, VAD prevalence for children from 1 to 4 years old is 27.3% and, in this case, there is no mandatory fortification programs in the country. Interactions between micronutrients are not unknown on health and nutrition field, the most recognized is that between calcium and vitamin D; besides, there is evidence from an epidemiological perspective that VAD and ID are linked in some way, fact supported for some studies using cellular and animal models. This study has the hypothesis that vitamin A regulates in some way the iron homeostasis and its metabolic role, and has three approaches: weight gain, biochemical and hematological parameters and molecular markers of iron homeostasis. We designed a study with four experimental diets with different ratios of iron and vitamin A (sufficient, insufficient and deficient) and a control diet with a sufficient supply of both micronutrients. The quantity of animals was calculated statistically giving seven animals per group for 35 animals. The rats started the experiment at weaning (21 days-old) and received food and water at libitum for six weeks, during this time food intake and weight were recorded each week. At sixth week the animals were euthanized and samples from blood and tissues of interest (liver, spleen and duodenum) were taken for analysis of biochemical and hematological indicators in blood and PCR and Western Blot test in tissues for the analysis of hepcidin, ferritin, transferrin receptors, transferrin and interleukin-6 as proteins of interest.La anemia por deficiencia de hierro (IDA) y la deficiencia de vitamina A (VAD) hacen parte del grupo de las deficiencias por micronutrientes definidas por la OMS como de interés mundial. En el caso de Colombia, la prevalencia de IDA en niños de 1 a 4 años es de 14.8% y la anemia está en 24.7% para niños entre 6 y 59 meses, algo paradójico si se tiene en cuenta que desde 1996 es obligatorio fortificar la harina de trigo con hierro. De otro lado, la prevalencia de VAD es de 27.3% para el mismo grupo poblacional, en este caso hasta el día de hoy no existe ningún tipo de fortificación obligatoria en el país. Las interacciones entre nutrientes no son algo desconocido en el campo de la salud y la nutrición, la más reconocida es la existente entre calcio y vitamina D; además, existe evidencia desde el punto de vista epidemiológico de que la VAD y la ID tienen algún tipo de relación, hecho que ha sido soportado por algunos estudios en modelos celulares y animales. Este estudio parte de la hipótesis de que la vitamina A regula de alguna forma la homeostasis del hierro y su rol metabólico, y aborda tres enfoques: ganancia de peso, parámetros bioquímicos y hematológicos y biomarcadores de la homeostasis del hierro.Doctorado en BiocienciasDoctor en Biociencia

Caracterización de facetas en un sector del cañón del río Buey mediante MDE

Maestrí

La profesión de Fe de Pedro en Mateo 16,13-20 desde las miradas Cristiana Católica y Cristiana Protestante

Licenciado (a) en Ciencias ReligiosasPregrad