Among the applications of superconductivity for electrical power systems, for several years cables have been attracting great interest at an international level, thereby reaching a high TRL. Superconducting cables, in fact, give the possibility of transporting large quantities of electrical energy with very limited losses compared to conventional cables as long as they operate below the critical temperatures of the superconducting materials used (liquid nitrogen temperatures or lower).

At a national level, in the three-year period 2022-2024 RSE continued its activities in continuity with what has already been carried-out in the previous three-year periods and in particular in this report the research activity is mainly focused on the use of MgB2 for the development of superconducting cables. The results of a critical state-of-the-art research are shown with particular reference to the methodologies for the analysis of failure and fault conditions in superconducting cables for power transmission.

The use of the OSCaR (Optimization tool for Superconducting Cable Research) software for the techno-economic optimization of the design parameters of a DC MgB2 cable and the related refrigeration system is then discussed. OSCaR was originally developed for AC HTS cables, so the first part of the dedicated chapter illustrates the main changes made to the algorithm to parameterize costs, losses and design factors referring to DC MgB2 cables; in the second part, some examples of parametric analyzes aimed at identifying the variation in line costs and losses as function of project parameters (such as length, transmitted power and line voltage) are reported.

Finally, the problem of modeling the motion in forced convection of the refrigerant fluids inside the cryostat of superconducting cables was addressed. Starting from the conservation equations of energy, momentum and mass, the dynamic model is built in non-stationary conditions and is solved numerically by discretizing the duct along the axis of the duct itself. The simulation results are shown and discussed in detail considering the case of the single-chamber cryostat and the case of the double-chamber cryostat with two cryogenic fluids.

The Report is available on the Italian site