Selective active filter applied to an arc furnace adjusted to harmonic emission limitations

This paper describes how to calculate the dif-ferent harmonic sequences that should be filtered with ashunt selective active filter, for two control alternatives: load current measurement or line current measurement. These results are then generalized for shunt hybrid selective filters. Passive parameters are chosen considering the resonances with the electric system that appear. Design basis are defined in order to obtain a minimum cost filter which also meet the applicable regulations requirements. Finally, results showing the potentiality of the selective filter controlled for the proposed methods are reported

Selective active filter with remote harmonic distortion control

PostprintThis paper presents the calculation methods for the different filtering blocks of a selective active filter in order to minimize the active filter inverter size, keeping the harmonic emissions at the limits stated by the applicable regulations. Since it may be necessary to comply with the regulations at a remote place with respect to the active filter location, the method has been extended to this case. In order to validate the simulations, measurements which were made at a real application - and arc furnace - were used. Finally, the simulated results obtained with a remote hybrid filter were compared with those obtained when an active filter is installed directly at the place where the harmonic emission regulations must be met. The comparison shows that remote compensation is an alternative to be seriously considered. The results are similar to those obtained with local compensation and the cost may be substantially lower

Filtro activo instantáneo de corrientes armónicas : FAICA

Proyecto I+D (llamado CSIC 1999)Objetivos generales y específicos. Realizar un aporte significativo a la teoría de los filtros activos en cuanto a la caracterización de los armónicos de corriente a partir del últimamente revalorizado concepto de la potencia instantánea y su descomposición en componentes activa, reactiva y armónicas como funciones en el dominio del tiempo. Este enfoque es especialmente apto para la compensación eficiente en forma dinámica de efectos no lineales en la red, tarea hasta ahora realizada en forma parcial mediante sistemas pasivos y modelos en el dominio de la frecuencia. Desarrollar técnicas modernas de control en tiempo real de los filtros activos. Lograr contar en el país con el conocimiento necesario a los efectos de contribuir a la solución técnica práctica del problema planteado, conocimiento que permita comprender todos los aspectos involucrados, las diferentes opciones tecnológicas, la evolución futura de las mismas y la capacidad de diseño y especificación de requerimientos para su posterior implementación en la Industria Nacional o Regional

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Diseño y simulaciones de un filtro activo selectivo de las corrientes armónicas de un horno de arco

En este trabajo se presentan los modelos y los resultados de las simulaciones realizadas para analizar el comportamientode los filtros activos selectivos en una instalación real de un horno de arco. En la primera parte se muestra cómo se realizaron y verificaron los cálculos para obtener las corrientes consumidas por el horno de arco a partir de registros de corrientes y tensiones tomados en un punto alejado de la instalación. Luego se presenta el modelo de simulación y los resultados del sistema eléctrico y del filtro activo diseñados. Por último se muestra el diseño de un inversor de tensión del filtro activo necesario para que los filtros tomaran la corriente armónica deseada

Building Training Methodology: Preparing Invigilators for Active, In-person, Exam Management

This study assesses effective training methods that support in-person, post-graduate, exam invigilators to build awareness of institutional policies as well as heighten their comfort and confidence with invigilating in the exam setting. Vigilant, active invigilators are considered effective in reducing student cheating behaviour on exams (Alabi, 2014; Attoh Odongo et al., 2021; Feng &amp; Ouyang, 2021; Siniver, 2013). This study followed 26 exam invigilators of varying experience through pre-training, training, and post-exam invigilation. Invigilators completed an online survey prior to participating in an in-person, half-day training session, self-identifying existing levels of experience, policy knowledge, and comfort/confidence in the exam setting in numerous situations. Upon completion of an in-person training session in a group setting, they completed a second online survey, which showed overall improvement. Invigilators were then assigned a live, in-person invigilation shift and following this, completed a third online survey. The study concludes that the training methods implemented foster confident and capable exam invigilators who support students’ compliance with academic integrity. With the shift to online testing during the COVID-19 pandemic, consideration needs to be given as to whether in-person invigilators retain the knowledge when they experience lengthy lapses of employment, and how their learned skills may be transferable to the online environment.

Series and parallel calculations methods for the reference current values in a selective shunt active filter

In this paper, the input/output transfer functions involved in a selective filtering using shunt active filters are analyzed. Their dependence on the employed control method for harmonic current filtering is studied. When performing selective filtering of harmonic sequences, the I/O transfer functions may have non-real terms. For those cases, a suitable frequency-domain analysis method, which takes into account both positive and negative current sequence filtering, is presented. The calculation procedure for the active filter reference current is then analyzed. The series and parallel calculation methods are presented and compared. The advantages of each method depending on the use of load or line current control are shown. The interference between the different filtering blocks obtained by using both series and parallel calculation methods is also shown

Control strategies of selective harmonic current shunt active filter

PostprintThis paper presents the possible calculation methodologies in orden to design a selective shunt active filter. For realizing to selective extraction of harmonic sequences the modulation - filter - demodulation technique is used. The fundamental equations of this method are established in the case of pq theory showing its equivalence with the SRF (Synchronus Reference Frame) method. In order to prove the proposed ways of calculation real non-periodic currents data with a great harmonic distortion of an arc furnace are used, with the good results achieve shows the ability of filtering in a selective and controlled way the undesired current harmonics