Análise de perdas em sistemas de energia que empregam materiais supercondutores de alta temperatura

Dissertação apresentada para obtenção do Grau de Doutor em Engenharia Electrotécnica e de Computadores, especialidade em Energia, pela Universidade Nova de Lisboa, Faculdade de Ciências e TecnologiaA descoberta dos materiais supercondutores de alta temperatura, arrefecidos a azoto líquido, deram início à criação de vários protótipos de dispositivos de potência, nomeadamente de transformadores. Nestes dispositivos a optimização do rendimento é um aspecto fundamental uma vez que, a melhoria de apenas algumas décimas percentuais corresponde a uma poupança energética considerável e, tanto maior, quanto maior for a potência da máquina. Os transformadores supercondutores permitem diminuir consideravelmente as perdas óhmicas nos enrolamentos, uma vez que o cobre tradicional é substituído por materiais com resistência eléctrica quase nula. No entanto, as perdas magnéticas no núcleo mantêm-se iguais às dos transformadores convencionais ou são agravadas, caso os núcleos sejam mantidos a baixa temperatura. Assim, a análise do comportamento a baixa temperatura dos materiais estruturais e funcionais que constituem as máquinas tornou-se mais importante, uma vez que uma optimização na escolha destes materiais poderá contribuir ainda mais para a optimização da máquina. Neste trabalho são determinadas as principais propriedades magnéticas de três materiais magnéticos macios, à temperatura do azoto líquido (77 K) e à temperatura ambiente (298 K). O principal objectivo é determinar se os materiais magnéticos seleccionados para funcionarem em máquinas à temperatura de 77 K, deverão ser os mesmos que os utilizados em máquinas que operam à temperatura ambiente. Os materiais escolhidos para os ensaios são usualmente utilizados no fabrico de núcleos de transformadores convencionais, e consistem num aço de grão não orientado e em dois aços de grão orientado, todos com diferentes espessuras. Essencialmente por comparação, é analisado também o comportamento magnético de uma liga magnética amorfa, utilizada em núcleos de transformadores

Implementation Framework for Energy Flexibility Technologies in Alkmaar and Évora

This research was funded by POCITYF, (FP7 grant agreement No 864400).As energy generation based on renewable resources does not always match energy consumption profiles, Positive Energy Districts (PEDs) should embody energy flexibility technologies to decrease possible negative impacts on existing grids due to, e.g., reverse power flows. As part of the EU H2020 Smart Cities and Communities project POCITYF, the cities Alkmaar (NL) and evora (PT) aim to support the deployment and market uptake of such districts and in doing so demonstrate innovative and integrated technologies to enable flexibility in the energy system. This paper addresses implementation conditions for energy flexibility technologies that help cities to engender the expected impact and ensure replication of these technologies to other sites. It aims to guide both urban planners and technology solution providers through pitfalls and opportunities that can appear during the design and implementation of PEDs. Taking this into consideration, the RUGGEDISED innovation and implementation framework for smart city technology was taken as a starting point to describe and analyze the experiences in Alkmaar and evora.publishersversionpublishe

Design Aspects and Test of an Inductive Fault Current Limiter

Magnetic shielding inductive fault current limiters with high temperature superconducting tapes are considered as emerging devices that provide technology for the advent of modern power grids. The development of such limiters requires magnetic iron cores and leads to several design challenges regarding the constitutive parts of the limiter, namely the primary and secondary windings. Preliminary tests in a laboratory scale prototype have been carried out considering an assembly designed for simplicity in which the optimization of the magnetic coupling between the primary and secondary was not the main focus. This work addresses the design configuration of an inductive current limiter prototype regarding the assembly of the primary and secondary windings in the core. The prototype is based on a closed magnetic core wound by a primary, built from a normal electric conductor, and a short-circuited secondary, built from first generation superconducting tape. Four different design configurations are considered. Through experimental tests, the performance of such prototype is discussed and compared, in terms of normal and fault operation regimes. The results show that all the configurations assure effective magnetic shielding at normal operation regime, however, at fault operation regime, there are differences among configurations

Development of a Simulink Model of a Saturated Cores Superconducting Fault Current Limiter

Part 14: Energy: SimulationInternational audienceSuperconducting fault current limiters are considered as emerging devices for the advent of modern power grids. Those limiters as well as other electric power grid applications have been developed in the last years in order to support the increased penetration of dispersed generation. The development of such limiters requires new design tools that allows to simulate those devices in electrical power grids with different voltage ratings and characteristics. This work presents a methodology to simulate the behaviour of saturated core type limiters based on its characteristic curves. A prototype is tested to obtain its characteristic and then the methodology is implemented in Simulink. The simulation carried out by the proposed methodology is compared with a real test

Design Aspects and Test of an Inductive Fault Current Limiter

Magnetic shielding inductive fault current limiters with high temperature superconducting tapes are considered as emerging devices that provide technology for the advent of modern power grids. The development of such limiters requires magnetic iron cores and leads to several design challenges regarding the constitutive parts of the limiter, namely the primary and secondary windings. Preliminary tests in a laboratory scale prototype have been carried out considering an assembly designed for simplicity in which the optimization of the magnetic coupling between the primary and secondary was not the main focus. This work addresses the design configuration of an inductive current limiter prototype regarding the assembly of the primary and secondary windings in the core. The prototype is based on a closed magnetic core wound by a primary, built from a normal electric conductor, and a short-circuited secondary, built from first generation superconducting tape. Four different design configurations are considered. Through experimental tests, the performance of such prototype is discussed and compared, in terms of normal and fault operation regimes. The results show that all the configurations assure effective magnetic shielding at normal operation regime, however, at fault operation regime, there are differences among configurations

Young-onset rapidly progressive ALS associated with heterozygous FUS mutation

© 2017 World Federation of Neurology on behalf of the Research Group on Motor Neuron DiseasesWe report a 36-years-old Cape Verdean man who presented with respiratory insufficiency due to rapidly progressive sporadic amyotrophic lateral sclerosis (ALS), in whom FUS mutation c.1551C > G (p.Hist517Gln) in heterozygosity was identified, a finding previously described as non-pathogenic. The only previous report on this mutation was in a family from Cape Verde in which four members developed ALS; all were homozygous for the mutation. This case shows that this FUS mutation presents a highly variable penetrance and expressivity.This work was partially supported by OnWebDuals project (JPND-PS/0001/2013) and MG holds a grant from the project. This is an EU Joint Programme - Neurodegenerative Disease Research (JPND) project. The project is supported through the following funding organisation under the aegis of JPND - www.jpnd.eu: Germany, Bundesministerium für Bildung und Forschung (BMBF); Poland, Narodowe Centrum Badań i Rozwoju (NCBiR); Portugal, Fundação a Ciência e a Tecnologia (FCT); Sweden, Vetenskapsrådet (VR).info:eu-repo/semantics/publishedVersio

Young-onset rapidly progressive ALS associated with heterozygous FUS mutation

© 2017 World Federation of Neurology on behalf of the Research Group on Motor Neuron DiseasesWe report a 36-years-old Cape Verdean man who presented with respiratory insufficiency due to rapidly progressive sporadic amyotrophic lateral sclerosis (ALS), in whom FUS mutation c.1551C > G (p.Hist517Gln) in heterozygosity was identified, a finding previously described as non-pathogenic. The only previous report on this mutation was in a family from Cape Verde in which four members developed ALS; all were homozygous for the mutation. This case shows that this FUS mutation presents a highly variable penetrance and expressivity.This work was partially supported by OnWebDuals project (JPND-PS/0001/2013) and MG holds a grant from the project. This is an EU Joint Programme - Neurodegenerative Disease Research (JPND) project. The project is supported through the following funding organisation under the aegis of JPND - www.jpnd.eu: Germany, Bundesministerium für Bildung und Forschung (BMBF); Poland, Narodowe Centrum Badań i Rozwoju (NCBiR); Portugal, Fundação a Ciência e a Tecnologia (FCT); Sweden, Vetenskapsrådet (VR).info:eu-repo/semantics/publishedVersio

Validation and Application of Sand Pile Modeling of Multiseeded HTS Bulk Superconductors

This work was supported by national funds through FCT Fundacao para a Ciencia e a Tecnologia, under project PEst-OE/EEI/UI0066/2011Sand pile and Bean models have already been applied to describe single grain HTS bulks. An extension to that approach was used to model multiseed bulks, needed for several practical applications as electric motors or flywheels with superconducting bearings. The use of genetic algorithms was then proposed to determine intra- and intergrain current densities, and application to two and three seeds samples using trapped flux experimental measurements was exemplified. However, this model assumed some simplifications, as equal properties in grain boundaries between neighboring grains. In this paper an extension to this methodology is proposed and evaluated by analyzing measurements performed in plans at different distances from surfaces of samples with three seeds. Discussion of its influence on a practical application is also explored.authorsversionpublishe