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International audience; The volume integral equation method based on the current vector potential approximated by means of edge element basis function is a well-established approach for 3D eddy currents computation. Within this approach the unknowns of the problem are expressed in terms of projection of the current vector potential along the edges of the discretization and a solving system is obtained based on tree/cotree decomposition of the primal graph. Due to its integral nature, an interpretation of the method in terms of circuits can be made. In this paper, the link between the volume integral equation method and the circuit is investigated and the numerical model is formulated in terms of a distributed parameter equivalent RL circuit. The numerical equivalent circuit is applied for investigating the lateral levitation force between a PM and a bulk superconductor with axial symmetry. The comparison between calculated and measured values is presented.

A three-year research project, called DRYSMES4GRID, was recently funded by the Italian Minister of Economic Development, Italy. The project is aimed to demonstrate the feasibility of cost-competitive SMES based on magnesium diboride (MgB2) with a cryogen-free cooling by means of the manufacturing and the testing of a demonstrator with an objective rating of 500 kJ/200 kW. The preliminary design, concerning the definition the geometry of the coil and the reference MgB2 conductor based on the functional requirements of the system, is first discussed. The detailed design of the coil, aimed at producing the information and the technical drawings needed for the manufacturing of the coil, is then presented. The mechanical behavior of the coil during cool down and successive energization up to the nominal transport current is analyzed and the compatibility of stress and strain with allowable limits of the conductor is verified. The distribution of electrical stress on the coil during the switching of the power electronic converters is also calculated for the proper design of electrical insulation. Results of quench analysis are also presented showing that the maximum hot spot temperature reached when the coil is discharged is within the design value. Evaluation of the thermal load due to radiation, conduction through the supports, current leads and AC loss is presented. The same methodology has been applied on another superconducting application in order to design the SC coil of a Saturated Iron superconductive Fault Current Limiter (SI-SFCL) at Changwon National University, South Korea. The SI-SFCL consists of three main parts: one magnetic iron-core, one normal conductive primary coil (CPC), and one superconducting secondary coil (SSC). The design of the SSC was based on the terms of shape, wire types, required fault current limit and protection aspects.

SMES technology based on MgB2 superconductor and cryogenic-free cooling can offer a viable solution to power-intensive storage in the short term. One of the main obstacles to the development of dry-cooled SMES systems is the heat load removal due to the AC loss of the superconductor during fast charging and discharging cycles at high power. Accurate knowledge of the amount and distribution of AC loss in the coil is of paramount importance for the sizing and the design of the cooling system and for assessing the possible operational limits of the technology. In this manuscript, the AC loss of a 500 kJ/200 kW multifilamentary MgB2 SMES during charge–discharge cycling at full power is numerically investigated. The methodology and assumptions of the calculation are briefly resumed, and numerical results are reported and discussed in detail. In particular, the time profile and the distribution of the dissipated power all over the coil are reported. An average dissipation of 85.5 mW/m is found all over the coil during one charge–discharge cycle at full power, with a peak of 150.1 mW/m in the turns lying at the ends of the coil.

The paper reports the results of the test and modelling activities carried out on large commercial supercapacitor cells at high current. Four commercials cells, with rated capacitance of 3000 F and rated voltage of 2.7 V, are considered. All cells are submitted to consecutive charge/discharge cycles at constant current. A test current in the range 80-130 A is used, which is comparable with the maximum operating current (up to 150 A) that the cells can reach in practical operations. A circuit model of the cells, able to reproduce the most relevant dynamic behavior, with a good compromise between accuracy, simplicity and robustness of the model's parameters, is also developed and validated against the experimental data. It is shown that all the investigated commercial cells are characterized by similar phenomena and comply with the same circuit model. Moreover, it is shown that the circuit parameters of the cells are in the same range and are weakly dependent on the test current. The obtained circuit parameters are accurately reported for all the cells and made fully accessible to users.

A three-year research project, called DRYSMES4GRID, was recently funded by the Italian Minister of Economic Development, Italy. The project, which involves five Italian partners (companies, universities, and research institutes), is aimed to demonstrate the feasibility of cost-competitive SMES based on magnesium diboride (MgB2) with a cryogen-free cooling by means of the manufacturing and the testing of a demonstrator with an objective rating of 500 kJ/200 kW. This rating is deemed suitable for disclosing the critical technological aspects of all components in view of practical applications. A further goal of the project is the assessment of the technical and economic benefits that the SMES can bring to real-world electric grids. The general outline and technical objectives of the project are presented in this paper. Preliminary design assumptions and results concerning the MgB2 coil and the power condition system are also discussed. © 2018 IEEE.