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Abstract. The scope of this paper is to adapt the standard mean-variance model of Henry Markowitz theory, creating a simulation tool to find the optimal configuration of the portfolio aggregator, calculate its profitability and risk. Currently, there is a deep discussion going on among the power system society about the structure and architecture of the future electric system. In this environment, policy makers and electric utilities find new approaches to access the electricity market; this configures new challenging positions in order to find innovative strategies and methodologies. Decentralized power generation is gaining relevance in liberalized markets, and small and medium size electricity consumers are also become producers ("prosumers"). In this scenario an electric aggregator is an entity that joins a group of electric clients, customers, producers, "prosumers" together as a single purchasing unit to negotiate the purchase and sale of electricity. The aggregator conducts research on electricity prices, contract terms and conditions in order to promote better energy prices for their clients and allows small and medium customers to benefit improved market prices.

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One potential advantage of the application of superconducting materials in electrical machines is the possibility to build lighter and compact devices by removing iron. These machines find applications, e.g., in systems where cryogenics is already available, or in naturally cryogenic environments. The design of motors with high temperature superconductors (HTS) presents issues unconsidered in classical machines, besides considerations on cryogenics, such as HTS brittleness or mechanical restrictions. Moreover, HTS' electromagnetic properties also degrade due to flux density components, which arise if there is no iron to guide magnetic flux. Several aspects must thus be considered in the design stage, as applications may turn less attractive or even unfeasible. In this paper these issues are detailed, and a numerical methodology for the design of an all superconducting (without iron or conventional conductors) linear synchronous motor is presented.

Abstract. Amongst applications of high temperature superconductors, fault current limiters are foreseen as one of the most promising in power systems. Several topologies have been developed in the last years, taking advantage of different superconductors' properties. Increasing distributed generation (DG) penetration, based on renewable energy, adds new short-circuit sources to electrical grids, which brings several energy quality and protection issues. Superconducting fault current limiters can obviate these problems, representing thus an enabling technology for DG penetration. In this paper current limiter topologies are presented, its operations principles, strengths and weaknesses, in the context of these DG grids. In the end, future trends are discussed.

Abstract. Taking into consideration the development and integration of electrical machines with lower dimensions and higher performance, this paper presents the design and development of a three-phase axial flux disc motor, with 50 Hz frequency supply. It is made with two conventional semi-stators and a rotor, which can be implemented with a conventional aluminum disc or a high temperature-superconducting disc. The analysis of the motor characteristics is done with a 2D commercial finite elements package, being the modeling performed as a linear motor. The obtained results allow concluding that the superconductor motor provides a higher force than the conventional one. The conventional disc motor presents an asynchronous behavior, like a conventional induction motor, while the superconductor motor presents both synchronous and asynchronous behaviors.

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