Analysis of a total integration of renewable energy in Catalonia through a dynamic virtual power plant model and the use of hydrogen as a method of energy production stabilization

Several models and scenarios have been developed to understand the dynamics and implications of integrating renewable energy technologies into the grid. In this document, the focus was on photovoltaic (PV), wind power, hydropower, and hydrogen systems facing Catalonia’s electric demand. In the process to elaborate a functional model, several factors are taken into account such as power generation, storage, and demand, aiming to minimize the levelized cost of energy (LCOE) and identify cost-effective solutions. The importance of the impact of renewable energy shares, the role of nuclear and gas facilities, and the potential of hydrogen as a storage medium and versatile energy carrier are relevant topics that incorporates new variables and corresponds to the increase of the diversity of sources needed to face climatic change. Considerations such as production limits, hydrogen limited to absorbs electricity and generation in function of the grid requirements, LCOE dynamics, and policy frameworks were also emphasized in order to develop a general system that supports to understand how the natural response of the system in changes on demand in function of the available sources could b

Improved harmonic performance of cascaded H-Bridge converters with thermal control

Among multilevel converter topologies, the cascaded H-bridge converter (CHB) is one suitable solution for multiple applications such as flexible ac transmission systems and motor drives. CHB presents a natural high modularity because it is formed by the serial connection of H-bridges. This paper deals with a CHB where the cells do not have the same aging because the maintenance during the years of operation forces to replace some damaged cells of the converter with new or repaired ones. A method based on clamping one power cell can be used to reduce the power losses of that cell reducing its temperature and increasing its lifetime. However, clamping one cell of the CHB introduces high harmonic distortion around twice the carrier frequency due to the CHB unbalanced operation when a conventional phase-shifted PWM is applied. A deep harmonic distortion analysis of the CHB output voltage with thermal control based on clamping one cell is presented. Using this analysis, the harmonic distortion at twice the carrier frequency is eliminated applying a non-conventional phase-shifted PWM where the angles between the carriers of consecutive power cells are modified. Experimental results show how the thermal control applying the clamping of a power cell is achieved whilst the harmonic distortion around twice the carrier frequency is eliminated

Model predictive control: a review of its applications in power electronics

Model-based predictive control (MPC) for power converters and drives is a control technique that has gained attention in the research community. The main reason for this is that although MPC presents high computational burden, it can easily handle multivariable case and system constraints and nonlinearities in a very intuitive way. Taking advantage of that, MPC has been successfully used for different applications such as an active front end (AFE), power converters connected to resistor inductor RL loads, uninterruptible power supplies, and high-performance drives for induction machines, among others. This article provides a review of the application of MPC in the power electronics area

Sampling-time harmonic control for cascaded H-bridge converters with thermal control

Cascaded H-bridge converter (CHB) is a multilevel topology that is a well-suited solution for multiple applications such as flexible ac transmission systems or motor drives. This paper is focused on a CHB where the cells present an aging mismatch. This can be caused by the maintenance operation which forces the replacement of some damaged cells of the converter with new or repaired ones. In this paper, a new improved approach of the active thermal control (ATC) of the CHB using discontinuous pulsewidth modulation (PWM) (D-PWM) is presented. The D-PWM technique is used to reduce the power losses of one cell reducing its average temperature in order to increase its remaining lifetime. However, the combination of D-PWM with traditional phase-shifted PWM (PS-PWM) introduces high harmonic distortion in the output voltage of the CHB converter at twice the carrier frequency. A detailed harmonic distortion analysis of the CHB output voltage when the D-PWM based ATC is active is presented. From this analysis, a modification of the traditional PS-PWM is derived to eliminate the harmonic distortion at twice the carrier frequency. Experimental results show how the ATC using D-PWM is achieved whereas the harmonic distortion around twice the carrier frequency is eliminated. © 1982-2012 IEEE

Power routing: a new paradigm for maintenance scheduling

Currently, the necessity of efficient and reliable power systems is also increasing because of the strict requirements that standards and regulations impose, but still costs have to remain low. The monitoring and control of the components' lifetime can lead to reduce maintenance costs. However, overcoming the related challenges is not a straightforward task, as it involves knowledge of power device physics, smart management of electrical quantities, and optimal maintenance planning and scheduling. It represents a multidisciplinary issue being faced in the last decade

Boron-Bearing Kornerupine from Fiskenaesset, West Greenland: A Reexamination of Specimens from the Type Locality

In 1884, Lorenzen proposed the formula MgAI2SiO6 for his new mineral kornerupine from Fiskenæsset and did not suspect it to contain boron. Lacroix and de Gramont (1919) reported boron in Fiskenæsset kornerupine, while Herd (1973) found none. New analyses (ion microprobe mass analyser and spectrophotometric) of kornerupine in three specimens from the type locality, including the specimens analysed by Lorenzen and Herd, indicate the presence of boron in all three, in amounts ranging from 0.50 to 1.44 wt.% B203, e.g. (Li0.04 Na0.01 Ca0.01) (Mg3.49 Mn0.01 Fe0.17 Ti0.01 Al5.64)Σ9.30 (Si3.67 Al1.02 B0.31)Σ5 O21 (OH0.99 F0.01) for Lorenzen\u27s specimen. Textures and chemical compositions suggest that kornerupine crystallized in equilibrium in the following assemblages, all with anorthite (An 92-95) and phlogopite (XFe = atomic Fe/(Fe + Mg) = 0.028-0.035): (1) kornerupine (0.045)-gedrite (0.067); (2) kornerupine (0.038-0.050)-sapphirine (0.032-0.035); and (3) kornerupine (0.050)-hornblende. Fluorine contents of kornerupine range from 0.01 to 0.06%, of phlogopite, from 0.09 to 0.10%. In the first assemblage, sapphirine (0.040) and corundum are enclosed in radiating bundles of kornerupine; additionally sapphirine, corundum, and/or gedrite occur with chlorite and pinite (cordierite?) as breakdown products of kornerupine. Kornerupine may have formed by reactions such as: gedrite + sapphirine + corundum + B203 (in solution) + H20 = kornerupine + anorthite + Na-phlogopite under conditions of the granulite facies. Boron for kornerupine formation was most likely remobilized by hydrous fluids from metasedimentary rocks occurring along the upper contact of the Fiskenæsset gabbro-anorthosite complex with amphibolite

In situ measurements of speciated atmospheric mercury and the identification of source regions in the Mexico City Metropolitan Area

In order to expand the currently limited understanding of atmospheric mercury source-receptor relationships in the Mexico City Metropolitan Area, real time measurements of atmospheric mercury were made at a downtown urban site, and a rural site on the outskirts of Mexico City, during March 2006. Numerous short-lived increases in particulate mercury (PHg) and reactive gaseous mercury (RGM) concentrations were observed at the urban site during the 17 day study, and less frequent increases in gaseous elemental mercury (GEM) concentrations were measured at both the urban and rural sites. The episodic increases observed were attributed to plume impacts from industrial point source emissions in and around Mexico City. Average concentrations and standard deviations measured during the study were as follows: i) urban site; PHg=187±300 pg m−3 [m superscript -3], RGM=62±64 pg m−3 [m superscript -3], GEM=7.2±4.8 ng m−3 [m superscript -3], and; ii) rural site; GEM=5.0±2.8 ng m−3 [m superscript -3]. Several source regions of atmospheric mercury to the urban and rural sites were determined using Concentration Field Analysis, in which atmospheric mercury measurements were combined with back trajectory data to determine source regions. Only some source regions correlated to mercury emission sources listed in the Federal Pollutant Release and Transfer Register, leaving the rest unaccounted for. Contributions of anthropogenic mercury point sources in and around Mexico City to concentration averages measured at the urban site during the study were estimated to be: 93±3% of reactive mercury (PHg and RGM), and; 81±0.4% of GEM. Point source contributions to GEM measured at the rural site were 72±1%. GEM and reactive mercury (PHg+RGM) were not found to correlate with biomass burning at either of the measurement sites.National Science Foundation (U.S.) (Grant 0514280)National Science Foundation (U.S.) (Grant 0511803)Science to Achieve Results Program (U.S.) (Grant R829798)United States. Environmental Protection Agenc

Prevenção primária do HIV na população imigrante: análise conceitual

Las estrategias establecidas para la prevención de VIH dirigidas a poblaciones inmigrantes, son diversas y poco específicas sobre las características de estos grupos. Objetivo: Analizar el concepto de “prevención primaria del VIH en población inmigrante”. Metodología: Se siguieron los pasos sugeridos por Walker y Avant, por lo que Se realizó una revisión estructurada de la literatura en diccionarios y bases de datos (Embase, Pubmed y Ebsco). Resultados: No se reporta evidencia de la existencia de una definición sobre el termino especifico, por lo que se realiza una propuesta que englobe las estrategias identificadas en la literatura, especifica en esta población. Conclusiones: la prevención primaria del VIH en migrantes se identifica como una gran oportunidad para fortalecer la cobertura de acceso universal a poblaciones vulnerables, además de ser un proceso complejo que requiere de un abordaje multidisciplinario en esferas estructurales, biomédicas y conductuales que se desarrollen con el eje ser de adaptaciones a las necesidades culturales.The strategies established for HIV prevention directed at immigrant populations are diverse and not very specific about the characteristics of these groups. Objective: To analyze the concept of "primary prevention of HIV in the immigrant population". Methodology: The steps suggested by Walker and Avant were followed, so a structured review of the literature in dictionaries and databases (Embase, Pubmed and Ebsco) was carried out. Results: There is no evidence of the existence of a definition on the specific term, so a proposal is made that encompasses the strategies identified in the literature, specific in this population. Conclusions: primary prevention of HIV in migrants is identified as a great opportunity to strengthen coverage of universal access to vulnerable populations, as well as being a complex process that requires a multidisciplinary approach in structural, biomedical and behavioral areas that are developed with the axis being adaptations to cultural needs.As estratégias estabelecidas para a prevenção do HIV direcionadas às populações imigrantes são diversas e pouco específicas sobre as características desses grupos. Objetivo: Analisar o conceito de "prevenção primária do HIV na população imigrante". Metodologia: Foram seguidas as etapas sugeridas por Walker e Avant, sendo realizada uma revisão estruturada da literatura em dicionários e bancos de dados (Embase, Pubmed e Ebsco. Resultados: Não há evidências da existência de uma definição sobre o termo específico, portanto é feita uma proposta que engloba as estratégias identificadas na literatura, específicas nessa população. Conclusões: A prevenção primária do HIV em migrantes é identificada como uma grande oportunidade para fortalecer a cobertura do acesso universal a populações vulneráveis, além de ser um processo complexo que requer uma abordagem multidisciplinar em áreas estruturais, biomédicas e comportamentais desenvolvidas com o eixo sendo adaptações às necessidades culturais

Common-mode voltage mitigation of dual three-phase voltage source inverters in a motor drive application

Electric variable speed drives (VSDs) based on two VSDs connected to a multiphase machine are an attractive solution to replace high-power mechanic and hydraulic systems in many sectors of industry and transportation because they present high performance with reduced cost, volume and weight. Among the causes which affect the reliability of dual VSDs, the common-mode current flowing through the machine bearing is an important issue. This paper faces the mitigation of the common-mode current by reducing the common-mode voltage (CMV) generated by the operation of a dual VSD. The CMV reduction is carried out without introducing any extra device and/or passive filtering method. This CMV reduction is performed by applying a specific phase-displacement between the modulation strategies of each single inverter drive. The proposed technique has been evaluated in a down scaled experimental setup in order to test its effectivenes

The exposure of the hybrid detector of the Pierre Auger Observatory

The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a surface array to measure secondary particles at ground level and a fluorescence detector to measure the development of air showers in the atmosphere above the array. The "hybrid" detection mode combines the information from the two subsystems. We describe the determination of the hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector of the surface array. A detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure. We discuss the relevance of monitoring data collected during operations, such as the status of the fluorescence detector, background light and atmospheric conditions, that are used in both simulation and reconstruction.Comment: Paper accepted by Astroparticle Physic