Core losses analysis of the LCL filter inductor for SiC-based inverter

The ability of SiC devices to switch at high speed allows increasing significantly the power density in both converters and passive components, reducing their required size. To mitigate harmonic injection form inverters into the grid, in order to comply with power quality standards, an accurate filter design is required. Given its excellent performance, an LCL filter is the configuration most suitable in grid-connected power converters. Several parameters must be considered when designing an effective LCL filter, and the inverter-side inductor assumes a special importance because of its relevance to suppress high frequency harmonic content at the inverter side. One of the most relevant issues to be considered in the process of designing the LCL filter is the evaluation of core losses in the inverter-side inductor, which will determine the final temperature of the inductor. This paper analyses the core losses of the inverter-side inductor of an LCL filter. The proposed method is based on the computation of the current harmonics generated by the inverter and on Steinmetz’s empirical equation. As a result, core losses calculated taking into account several carrier and sideband harmonics show good agreement with the experimental values. When current harmonics are estimated by simulation, as it is done in the proposed design procedure, results are less accurate, but precise enough for a design procedure

An anti-islanding protection based on RoCoF compliant with ENTSO-E and IEC 62116

In case of unintentional islanding, distributed generation units must be able to detect it and disconnect from the grid in less than 2 seconds. In this work, a Rate of Change of Frequency (RoCoF) method has been developed for islanding detection. Since these algorithms are conditioned by the requirements of grid codes, ENTSO-E network code and IEC 62116 have been taken into account. The RoCoF anti-islanding algorithm has been developed in MATLAB-Simulink and implemented through rapid prototyping techniques in an FPGA ALTERA Cyclone V. To check the proposed protection algorithm, simulation tests have been carried out. Finally, the RoCoF anti-islanding protection has been validated using FPGA in the loop and experimentally in a real 20-kW inverter. © 2022, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved

Analysis of Finite Microstrip Structures Using an Efficient Implementation of the Integral Equation Technique

An efficient numerical implementation of the Integral Equation technique (IE) has been developed for the analysis of the electrical characteristics of finite microstrip structures. The technique formulates a volume version of the IE for the finite dielectric objects, and a standard surface IE technique for the metallic areas. The system of integral equations formu- lated are solved with special numerical techniques described in this paper. The input impedances of several microstrip antennas have been computed, showing good agreement with respect mea- surements. The technique has shown to be accurate even for complex geometries containing several stacked dielectric layers. The radiation patterns of the structures have also been com- puted, and measured results from real manufactured hardware confirm that backside radiation and secondary lobes are accurately predicted by the theoretical model. The paper also discuss a suitable excitation model for finite size ground planes, and investigates the possibilities for an independent meshing of the metallic areas and the dielectric objects inside a given geom- etry. The practical value of the approach derived is that microstrip circuits can be designed minimizing the volume and size of the dielectric substrates.This work has been supported bythe Spanish National Project ESP2001-4546-PE, and RegionalSeneca Project PB/4/FS/02

CNstream: A method for the identification and genotyping of copy number polymorphisms using Illumina microarrays

<p>Abstract</p> <p>Background</p> <p>Understanding the genetic basis of disease risk in depth requires an exhaustive knowledge of the types of genetic variation. Very recently, Copy Number Variants (CNVs) have received much attention because of their potential implication in common disease susceptibility. Copy Number Polymorphisms (CNPs) are of interest as they segregate at an appreciable frequency in the general population (i.e. > 1%) and are potentially implicated in the genetic basis of common diseases.</p> <p>Results</p> <p>This paper concerns CNstream, a method for whole-genome CNV discovery and genotyping, using Illumina Beadchip arrays. Compared with other methods, a high level of accuracy was achieved by analyzing the measures of each intensity channel separately and combining information from multiple samples. The CNstream method uses heuristics and parametrical statistics to assign a confidence score to each sample at each probe; the sensitivity of the analysis is increased by jointly calling the copy number state over a set of nearby and consecutive probes. The present method has been tested on a real dataset of 575 samples genotyped using Illumina HumanHap 300 Beadchip, and demonstrates a high correlation with the Database of Genomic Variants (DGV). The same set of samples was analyzed with PennCNV, one of the most frequently used copy number inference methods for Illumina platforms. CNstream was able to identify CNP loci that are not detected by PennCNV and it increased the sensitivity over multiple other loci in the genome.</p> <p>Conclusions</p> <p>CNstream is a useful method for the identification and characterization of CNPs using Illumina genotyping microarrays. Compared to the PennCNV method, it has greater sensitivity over multiple CNP loci and allows more powerful statistical analysis in these regions. Therefore, CNstream is a robust CNP analysis tool of use to researchers performing genome-wide association studies (GWAS) on Illumina platforms and aiming to identify CNVs associated with the variables of interest. CNstream has been implemented as an R statistical software package that can work directly from raw intensity files generated from Illumina GWAS projects. The method is available at <url>http://www.urr.cat/cnv/cnstream.html</url>.</p

Ensayo metodológico de planificación física de una autovía en el Estado Miranda (Venezuela)

La planificación física con base ecológica es fundamental para desarrollar el potencial ambiental y humano de un territorio. Sin embargo, en numerosas áreas de Latinoamérica hay carencias de información territorial que dificultan estos procedimientos. En esta línea, se ha realizado un ensayo metodológico de una planificación física de una autovía hipotética. Para ello se han realizado modelos en SIG (Sistemas de Información Geográfica) de capacidad territorial, riesgos, calidad, fragilidad e impacto ambiental, que se han integrado en una síntesis de planificación territorial. El objetivo final ha sido modelizar un mapa de impedancia o fricción frente a la autovía, para aplicar un algoritmo cost distance / cost path y obtener un trazado de autovía que optimizase la capacidad del territorio y minimizase el impacto ambiental. Se ha consolidado un aprendizaje y una primera transferencia I + D dirigida a la gestión territorial y a la toma de decisiones para diversos países de Latinoamérica