@article {OA5328, title = {Analysis of Characteristic Hysteresis Loops of Magnetic Shielding Inductive Fault Current Limiters}, journal = {IEEE Transactions on Applied Superconductivity}, volume = {23}, number = {3}, year = {2013}, note = {n/a}, pages = {5601004{\textendash}5601004}, abstract = {

Magnetic shielding inductive fault currentlimiterswith high temperature superconducting cylinders have previously been described by a characteristic (or maximum)hysteresisloop, built from properties of their constitutive parts, which allowed predicting their behavior in electrical grids. These preliminary results were based on finite elements simulations, but posterior experiments suggested limitations in the models. In order to investigate the application of these previous models to real devices, two laboratory scale prototypes were built with different types of superconducting material in the secondary, either bulk cylinder, either tape. Although the behavior of both devices is still approximately defined by a maximumhysteresisloop, differences in the shielding current response, when compared with previous model, must be incorporated in future models.

}, url = {http://oa.uninova.pt/5328/}, author = {Pedro Arsenio and Tiago Silva and Nuno Vilhena and Jo{\~a}o Pina and Anabela Pronto} } @article {OA5102, title = {Modelling and Simulation of Inductive Fault Current Limiters}, journal = {Physics Procedia}, volume = {36}, year = {2012}, note = {n/a}, pages = {1248{\textendash}1253}, abstract = {

Inductive superconducting fault current limiters have already demonstrated their technical viability in electrical networks. Its architecture and robustness make them potentially adequate for distribution networks, and this type of devices is considered as an enabling technology for the advent of embedded generation with renewable energy sources. In order to promote the growth and maturity of these superconducting technologies, fast design tools must be developed, allowing simulating devices with different materials in grids with diverse characteristics. This work presents advances in the development of such tool, which, at present stage, is an effective alternative to software simulations by finite elements methods, reducing dramatically computation time. The algorithms are now compared with experimental results from a laboratory scale prototype, showing the need to refine them.

}, url = {http://oa.uninova.pt/5102/}, author = {Jo{\~a}o Pina and Pedro Pereira and A. Gon{\c c}alves Pronto and Pedro Ars{\'e}nio and Tiago Silva} } @article {OA2428, title = {Reverse engineering of inductive fault current limiters}, journal = {Journal of Physics: Conference Series}, volume = {234}, number = {3}, year = {2010}, note = {n/a}, pages = {1{\textendash}9}, publisher = {IOP Publishing}, abstract = {

The inductive fault current limiter is less compact and harder to scale to high voltage networks than the resistive one. Nevertheless, its simple construction and mechanical robustness make it attractive in low voltage grids. Thus, it might be an enabling technology for the advent of microgrids, low voltage networks with dispersed generation, controllable loads and energy storage. A new methodology for reverse engineering of inductive fault current limiters based on the independent analysis of iron cores and HTS cylinders is presented in this paper. Their electromagnetic characteristics are used to predict the devices{\textquoteright} hysteresis loops and consequently their dynamic behavior. Previous models based on the separate analysis of the limiters{\textquoteright} components were already derived, e.g. in transformer like equivalent models. Nevertheless, the assumptions usually made may limit these models{\textquoteright} application, as shown in the paper. The proposed methodology obviates these limitations. Results are validated through simulations.

}, url = {http://oa.uninova.pt/2428/}, author = {J M Pina and P Su{\'a}rez and M Ventim Neves and A {\'A}lvarez and A L Rodrigues} } @unpublished {OA1962, title = {Impacto do mercado ib{\'e}rico de electricidade (MIBEL) no comportamento competitivo dos agentes produtores de energia el{\'e}ctrica}, year = {2009}, note = {n/a}, month = {May}, publisher = {FCT-UNL}, abstract = {

A presente Disserta{\c c}{\~a}o consiste num estudo do comportamento competitivo de entidades, produtoras e comercializadoras de energia el{\'e}ctrica, num per{\'\i}odo de tempo antes e ap{\'o}s a entrada em vigor do Mercado Ib{\'e}rico de Electricidade (MIBEL). Esse per{\'\i}odo de tempo engloba os meses entre Abril de 2007 e Abril de 2008, sendo que o MIBEL teve in{\'\i}cio a 1 de Julho de 2007. O estudo incide principalmente no grau de competitividade ou aus{\^e}ncia da mesma, que as referidas entidades adoptaram ap{\'o}s o come{\c c}o do MIBEL. Para poder efectuar essa avalia{\c c}{\~a}o, recorre-se a uma abordagem baseada em varia{\c c}{\~o}es conjecturais, que constituem um indicador desse grau de competitividade. Ou seja, as varia{\c c}{\~o}es conjecturais representam a convic{\c c}{\~a}o que determinada empresa X tem face ao comportamento que outra empresa Y adoptar{\'a} ap{\'o}s uma ac{\c c}{\~a}o efectuada pela empresa X. Por ac{\c c}{\~a}o depreende-se, por exemplo, uma redu{\c c}{\~a}o ou um aumento da quantidade de produ{\c c}{\~a}o de uma empresa. Se o valor da vari{\'a}vel conjectural for 0, as empresas encontram-se a concorrer {\`a} Cournot. Caso seja -1, as empresas encontram-se em concorr{\^e}ncia perfeita. Por outro lado, se o valor da varia{\c c}{\~a}o conjectural for superior a 0 pode existir uma situa{\c c}{\~a}o de conluio entre as empresas. De modo a obter estes valores das varia{\c c}{\~o}es conjecturais, utiliza-se e readapta-se um simulador de mercado di{\'a}rio, denominado SiMEC - Simulador do Mercado El{\'e}ctrico e do Carbono. Este simulador, que anteriormente simulava apenas per{\'\i}odos temporais precedentes ao MIBEL, foi reajustado de modo a incluir dados p{\'o}s MIBEL. Finalmente, s{\~a}o ent{\~a}o realizados gr{\'a}ficos comparativos e retiradas conclus{\~o}es acerca do comportamento das entidades face a altera{\c c}{\~o}es na estrutura do mercado de electricidade.

}, url = {http://oa.uninova.pt/1962/}, author = {Alexandra Tavares}, editor = {M{\'a}rio Neves and Jorge Sousa and Jo{\~a}o Pina} } @conference {OA791, title = {Topology of an Electrical Gearbox with Variable Poles for Induction and Superconducting Disc Motors}, booktitle = {X Portuguese-Spanish Congress in Electrical Engineering}, year = {2007}, note = {n/a}, abstract = {n/a}, url = {http://oa.uninova.pt/791/}, author = {In{\'a}cio Steve and Jo{\~a}o Pina and Stanimir Valtchev and M{\'a}rio Neves and Amadeu Rodrigues} } @conference {OA378, title = {Multipole Superconducting Synchronous Generator}, booktitle = {6th European Conference on Applied Superconductivity (EUCAS)}, year = {2003}, note = {n/a}, month = {September}, abstract = {n/a}, url = {http://oa.uninova.pt/378/}, author = {M. Caserza Magro and M{\'a}rio Neves and Athanasis Sfetsos and Jo{\~a}o Pina and Anabela Gon{\c c}alves} } @article {OA359, title = {Flux Modelling of Reluctance Machines with Bulk Superconducting Materials}, journal = {Electromotion Review}, year = {2003}, note = {n/a}, abstract = {n/a}, url = {http://oa.uninova.pt/359/}, author = {Athanasis Sfetsos and Jo{\~a}o Pina and Anabela Gon{\c c}alves and M{\'a}rio Neves and Amadeu Rodrigues} }