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Arsenio, Pedro, Tiago Silva, Nuno Vilhena, João Pina, and Anabela Pronto. "Analysis of Characteristic Hysteresis Loops of Magnetic Shielding Inductive Fault Current Limiters." IEEE Transactions on Applied Superconductivity. 23 (2013): 5601004. AbstractWebsite

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.

Sfetsos, Athanasis, João Pina, Anabela Gonçalves, Mário Neves, and Amadeu Rodrigues. "Flux Modelling of Reluctance Machines with Bulk Superconducting Materials." Electromotion Review (2003). AbstractWebsite
Tavares, Alexandra Impacto do mercado ibérico de electricidade (MIBEL) no comportamento competitivo dos agentes produtores de energia eléctrica. Eds. Mário Neves, Jorge Sousa, and João Pina. FCT-UNL, 2009. Abstract

A presente Dissertação consiste num estudo do comportamento competitivo de entidades, produtoras e comercializadoras de energia eléctrica, num período de tempo antes e após a entrada em vigor do Mercado Ibérico de Electricidade (MIBEL). Esse período de tempo engloba os meses entre Abril de 2007 e Abril de 2008, sendo que o MIBEL teve início a 1 de Julho de 2007. O estudo incide principalmente no grau de competitividade ou ausência da mesma, que as referidas entidades adoptaram após o começo do MIBEL. Para poder efectuar essa avaliação, recorre-se a uma abordagem baseada em variações conjecturais, que constituem um indicador desse grau de competitividade. Ou seja, as variações conjecturais representam a convicção que determinada empresa X tem face ao comportamento que outra empresa Y adoptará após uma acção efectuada pela empresa X. Por acção depreende-se, por exemplo, uma redução ou um aumento da quantidade de produção de uma empresa. Se o valor da variável conjectural for 0, as empresas encontram-se a concorrer à Cournot. Caso seja -1, as empresas encontram-se em concorrência perfeita. Por outro lado, se o valor da variação conjectural for superior a 0 pode existir uma situação de conluio entre as empresas. De modo a obter estes valores das variações conjecturais, utiliza-se e readapta-se um simulador de mercado diário, denominado SiMEC - Simulador do Mercado Eléctrico e do Carbono. Este simulador, que anteriormente simulava apenas períodos temporais precedentes ao MIBEL, foi reajustado de modo a incluir dados pós MIBEL. Finalmente, são então realizados gráficos comparativos e retiradas conclusões acerca do comportamento das entidades face a alterações na estrutura do mercado de electricidade.

Pina, João, Pedro Pereira, Gonçalves A. Pronto, Pedro Arsénio, and Tiago Silva. "Modelling and Simulation of Inductive Fault Current Limiters." Physics Procedia. 36 (2012): 1248-1253. AbstractWebsite

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.

Magro, Caserza M., Mário Neves, Athanasis Sfetsos, João Pina, and Anabela Gonçalves. "Multipole Superconducting Synchronous Generator." 6th European Conference on Applied Superconductivity (EUCAS). 2003. Abstract
Pina, J. M., P. Suárez, Ventim M. Neves, A. Álvarez, and A. L. Rodrigues. "Reverse engineering of inductive fault current limiters." Journal of Physics: Conference Series. 234 (2010): 1-9. AbstractWebsite

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' hysteresis loops and consequently their dynamic behavior. Previous models based on the separate analysis of the limiters' components were already derived, e.g. in transformer like equivalent models. Nevertheless, the assumptions usually made may limit these models' application, as shown in the paper. The proposed methodology obviates these limitations. Results are validated through simulations.

Steve, Inácio, João Pina, Stanimir Valtchev, Mário Neves, and Amadeu Rodrigues. "Topology of an Electrical Gearbox with Variable Poles for Induction and Superconducting Disc Motors." X Portuguese-Spanish Congress in Electrical Engineering. 2007. Abstract