Design for Passivity in the Z-Domain for LCL Grid-Connected Converters

This paper develops a design methodology aimed to shape passive the admittance of the LCL grid-connected voltage source converters (VSCs). A novel aspect of this work is the assessment of the range of frequencies for control design: due to discrete and PWM operation, the effectiveness of the control action is more and more reduced as frequency increases; in practice, system delays and non-linear effects tend to impair the passivity properties and also its experimental validation. However, as shown in this paper, those effects can be minimised by including the LCL filter as a part of an outer VSC admittance: this assumption is supported by the fact that high frequency disturbances (generated in the point of connection) are absorbed by the LCL capacitor branch, and hence, are not able to create a positive feedback in the VSC (i.e., the active component). By taking advantage of this remark, the inner VSC admittance can be shaped by a reduced order filter in the Z-domain, which mainly depends on the proportional and active damping (controller) gains. The design hypotheses and the control design methodology are verified by PLECS switching-mode simulations

Input-Admittance Passivity Compliance for Grid-Connected Converters With an LCL Filter

This work presents a design methodology and its experimental validation for the input-admittance passivity compliance of LCL grid-connected converters. The designs of the LCL filter parameters and discrete controller are addressed systematically, and suitable design guidelines are provided. The controller design is developed in the z-domain, with capacitor voltage based active damping used as degree of freedom to compensate for system delay effects. The role of resistive components in the circuit, which have inherent dissipative properties, is also discussed. As an outcome of the design, a passive input admittance shaping is obtained. The theoretical development is further verified in a low-scale prototype supplied from a controllable grid simulator. For the sake of generality, different combinations of resonant to sampling frequency are tested. Experimental results fully prove the input-admittance passivity compliance

Izaña Atmospheric Research Center. Activity Report 2015-2016

This report is a summary of the many activities at the Izaña Atmospheric Research Center to the broader community. The combination of operational activities, research and development in state-of-the-art measurement techniques, calibration and validation and international cooperation encompass the vision of WMO to provide world leadership in expertise and international cooperation in weather, climate, hydrology and related environmental issues

Modular medium voltage drive for demanding applications

Nowadays, several state-of-the-art multilevel converter topologies are used for numerous industrial medium-voltage (MV) high-power variable-speed drive applications. The 3-level neutral point clamped (3L-NPC) topology is one of those and is often used as a benchmark for various alternatives. In this paper, a 3L-NPC medium voltage special-purpose drive based on an integrated gate commutated thyristor (IGCT) is presented, highlighting the design paradigms followed in order to achieve highest performances at maximum possible flexibility. Modular hardware design supported by highly dynamic direct torque control, fulfills the needs of the demanding applications

Atención médica en el enfrentamiento a la COVID-19. Hospital Pediátrico Universitario de Cienfuegos, 2021-2022

Fundamento: la pandemia de COVID-19 tensó enormemente los servicios de salud en el mundo entero y Cuba no fue una excepción. Aunque la proporción de casos confirmados en niños fue menor, es necesaria la descripción de la atención médica a este sector de la población.Objetivo: describir la organización de los servicios médicos y morbilidad hospitalaria durante la COVID-19, de enero 2021 a febrero 2022, en el pediátrico de Cienfuegos.Métodos: estudio descriptivo realizado en el Hospital pediátrico de Cienfuegos sobre la atención médica a niños en Cienfuegos, durante la COVID-19. Se analizaron las variables número de casos, edad, sintomatología, casos ingresados en unidades de cuidados intensivos, egreso.Resultados: fueron ingresados 2758 pacientes confirmados de COVID-19; los meses de junio a septiembre aportaron el mayor número de casos, con agosto como más representativo con 46,4 %. Cienfuegos y Cumanayagua fueron los municipios con más casos; predominaron los menores de cinco años (88,3 %) fundamentalmente los menores de un año (49,2 %). La presentación clínica asintomática fue preponderante y sintomatología leve. Requirieron cuidados intensivos el 1,1 % del total y la letalidad fue de 0,04 %. El enfrentamiento a la enfermedad tuvo un carácter intersectorial; el cumplimiento de los protocolos y guías se dieron en un contexto donde primó la reorganización de los servicios y la gestión del conocimiento.Conclusiones: la atención médica oportuna y encaminada a alcanzar el mayor detalle científico asistencial, acompañado de una continua gestión del conocimiento para su adherencia permitió que la mayoría de los niños con COVID-19 egresaran de manera satisfactoria.</p