Dynamics estimation and generalized tuning of stationary frame current controller for grid-tied power converters

The integration of AC-DC power converters to manage the connection of generation to the grid has increased exponentially over the last years. PV or wind generation plants are one of the main applications showing this trend. High power converters are increasingly installed for integrating the renewables in a larger scale. The control design for these converters becomes more challenging due to the reduced control bandwidth and increased complexity in the grid connection filter. A generalized and optimized control tuning approach for converters becomes more favored. This paper proposes an algorithm for estimating the dynamic performance of the stationary frame current controllers, and based on it a generalized and optimized tuning approach is developed. The experience-based specifications of the tuning inputs are not necessary through the tuning approach. Simulation and experimental results in different scenarios are shown to evaluate the proposal.Peer ReviewedPostprint (published version

Frequency support properties of the synchronous power control for grid-connected converters

Grid-connected converters with primary frequency control and inertia emulation have emerged and are promising for future renewable generation plants because of the contribution in power system stabilization. This paper gives a synchronous active power control solution for grid-connected converters. As design considerations, the virtual angle stability and transient response are both analyzed, and the detailed implementation structure is also given without entailing any difficulty in practice. The analysis and validation of frequency support characteristics are particularly addressed. The 10 kW simulation and experimental frequency sweep tests on a regenerative source test bed present good performance of the proposed control in terms of showing inertia and droop characteristics, and the controllable transient response is also demonstrated.Peer ReviewedPostprint (author's final draft

New data about the geomorphological and paleoenvironmental evolution of the Cantabrian Coast during MIS 6-4: the Cobiḥeru Natural Monument (Asturias)

Se proporcionan nuevos datos sobre la geomorfología y evolución paleoambiental de la Costa Cantábrica durante el MIS 6–4 a partir del modelo espeleogenético de la Cueva de Cobḥi eru, incluyendo: (1) la identificación de 2 fases de relleno de la cueva relacionadas con condiciones más frías y etapas de nivel del mar bajo a 60–70 y 130–150 ka, (2) el inicio de un descenso del nivel del Mar Cantábrico en la transición entre el MIS 5-4, (3) la presencia de un ambiente abierto con poca vegetación en torno a 65 ka (MIS 4), (4) el descubrimiento del Elona quimperiana más antiguo, indicando el desarrollo de bosque caducifolio húmedo hace más de 350 ka, y (5) la relación entre la erosión de los abanicos torrenciales que cubrían el karst y la entrada de fauna fría a las cuevas de la costa de AsturiasNew data about the geomorphology and paleoenvironmental evolution of the Cantabrian Coast for the MIS 6-4 interval is derived from the speleogenetical model of the Cobḥi eru Cave. This data includes: (1) the identification of 2 phases of cave sedimentary infill related to cold conditions and global sea-level lowstand at ca. 60–70 and 130–150 ka, (2) set the timing for the beginning of sea-level lowering in the Cantabrian Sea in MIS 5-4 transition , (3) evidence of an open landscape with scarce vegetation around 65 ka (MIS 4), (4) the discovery of the oldest Elona quimperiana site, which suggest the development of wet deciduous forest in this coastal setting prior to 350 ka, and (5) to establish a link between karst exhumation due to erosion of overlying fluvial sediments and the introduction of the cold-adapted fauna in the coast caves of Asturia

Control proposals for the operation of power converters in wind power systems

The wind turbines based on Doubly Fed Induction Generators (DFIG) represent almost the 60% of the installed windpower worldwide. Nowadays most of the existing algorithms, used for regulating the production of active and reactive power in such systems, are based on control techniques that use rotational reference frames theories, where the dq0 is maybe the most popular. Despite of its good operation under balanced conditions its behaviour depends on a good phase synchronization, otherwise the different transformations cannot be performed with enough guarantees. Of course this kind of response is becomming insuficient, as far as the windpower penetration is increasing. This paper will present a new control topology for DFIG, that are connected using back to back inverters, that is able to behave better in case of faulty grids. Besides some proposals for improving the operation of the DFIG will be presented as well. The aim of that part is to extend the possibilities that the back to back inverters are able to offer to the generator system by means of including new functionalities, as the active filtering capability or the reduction of the flicker emission that will be later discussed.Postprint (published version

Glioma Diagnosis Aid through CNNs and Fuzzy-C Means for MRI

Glioma is a type of brain tumor that causes mortality in many cases. Early diagnosis is an important factor. Typically, it is detected through MRI and then either a treatment is applied, or it is removed through surgery. Deep-learning techniques are becoming popular in medical applications and image-based diagnosis. Convolutional Neural Networks are the preferred architecture for object detection and classification in images. In this paper, we present a study to evaluate the efficiency of using CNNs for diagnosis aids in glioma detection and the improvement of the method when using a clustering method (Fuzzy C-means) for preprocessing the input MRI dataset. Results offered an accuracy improvement from 0.77 to 0.81 when using Fuzzy C-Means.Ministerio de Economía y Competitividad TEC2016-77785-

Comparación de los marcadores de infección (PCR, temperatura corporal, eritrosedimentación y leucograma) en pacientes de terapia intensiva del Hospital Eugenio Espejo de junio - agosto del 2009

Se efectúa un estudio para determinar que la utilización de la Proteína C Reactiva hs es un marcador biológico de alta importancia como pronóstico de los procesos infecciosos e inflamatorios en la Unidad de Terapia Intensiva en la ciudad de Quito, el cual fue realizado en el transcurso de tres meses que corresponden desde junio- agosto del año 2009. Se tomó un total de 140 muestras de pacientes mayores a 16 años de edad. El estudio se lo ejecutó en el “Hospital Eugenio Espejo” Quito. Las determinaciones de la Proteína C Reactiva se realizó por medio del método PCR (LATEX) hs. Los resultados obtenidos en esta investigación, indican que la Proteína C Reactiva es un marcador muy sensible, el cual fue comparado con otros marcadores de infección, presentando los resultados esperados para el PCR, por tanto se demuestra que es una prueba útil y necesaria. Ya que puede elevarse rápidamente ante una infección independientemente del diagnóstico del paciente, lo que no ocurre con otros marcadores como: la temperatura corporal y la velocidad de sedimentación globular

Modelling and simulation of bifacial pv production using monofacial electrical models

In this paper, we investigate the use of monofacial PV models to simulate the production of bifacial PV systems over different albedos. Analytical and empirical models were evaluated using measured data obtained from three identical bifacial PV arrays: (1) with the backside covered by white plastic, (2) with normal albedo, and (3) with high albedo. The front-and rear-side irradiances were measured in order to integrate bifaciality of the modules into the models. The models showed good performance for non-real-time monitoring, especially under clear skies, and the analytical model was more accurate than the empirical model. The heatmap visualization technique was applied to six months of data in order to investigate the site conditions on the rear side of the modules as well as the accuracy of the models. The heatmap results of the rear- and front-sides irradiances showed that the installation conditions, such as the azimuth angles of the sun and the surrounding obstacles, had a strong impact on the energy received from the back of the modules. The heatmap results of the models validated the performance of the analytical model. The average daily errors for the analytical model were less than 1% and 3% for normal and high albedos, respectively.This work was supported by the SUDOKET SOE2/P1/E0677 project funded by FEDER of the EU under the Interreg-Sudoe program. The research leading to these results received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 712949 (TECNIOspring PLUS) and from the Agency for Business Competitiveness of the Government of Catalonia.Peer ReviewedPostprint (published version

Proyectos finales integradores : una alternativa para enseñar y aprender activamente

Este número de Reflexiones Pedagógicas busca presentar los proyectos finales integradores (PFI) como una opción de enseñanza y aprendizaje activo. Se explica qué son los PFI, así como las ventajas que se obtienen al hacer uso de estos en una o más asignaturas. Por otro lado, se relatan las experiencias que el programa de Ingeniería Biomédica ha encontrado en la implementación de PFI en algunas de sus asignaturas. Por último, se exponen algunos retos y desafíos inherentes a la implementación de esta alternativa pedagógica. Esperamos que lo compartido en este número sea de utilidad para continuar en la ruta del aprendizaje activo y significativo, el cual implica retos tanto para los docentes como para los estudiantes. Luego de lo vivido como equipo de profesores, consideramos que esta experiencia es altamente transferible a otros campos de conocimiento. Los resultados son gratificantes, así lo hemos evidenciado en cada momento con los estudiantes

Sistema de predicción por conjuntos a corto plazo sobre la Península Ibérica y Baleares

A short-range ensemble precipitation forecast system has been constructed over the Iberian Peninsula and Balearics by means of the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Model (MM5). The ensemble system onsists of ten members, each run with a different combination of two different initial conditions from global models, IFS-ECMWF and GFS-NCEP, and five different subgrid-scale physics configurations for one month period, October 2006. The mesoscale verification is made by using observational precipitation data of the Spanish Climatic Network. The created short-range ensemble shows high spread-skill correlation values for daily precipitation. However, the asymmetric shape of the rank histogram indicates some underdispersion, suggesting a biased behaviour. The Talagrand shows as well the underdispersive effect because of its asymmetric distribution. The Relative Operating Characteristic curve shows a very outstanding area indicating the good discrimination capacity. The reliability diagrams are also indicative of the good reliability of the forecasting system, depicting in general good agreement between forecast probability and the mean observed frequency. Because of that, the verification proves the usefulness of the forecasting system over the study area.This work has been partially supported by the research projects CGL2007- 61328/CLI and UE Safewind G.A. No. 213740