The energy systems of most countries around the world are rapidly evolving. In this transformation, it is desirable to increase the resilience of these systems, which can also be achieved through the use of new technologies to ensure electricity generation that responds to demand in order to avoid instability and blackouts. The exploitation of the properties of superconductors for realising elements such as current limiters is more than promising, even if it is still at the prototype stage.

This report describes the progress and results of research activities carried out regarding the development and application of new experimental characterisation and numerical modelling methods for the study of the behaviour of ReBCO-based 2G SAT (Superconducting High Transition Temperature) tapes for applications in SFCL (Superconducting Fault Current Limiter) devices in electricity grids.

These activities were developed according to the following two main macro themes:

• Theoretical and experimental activities for assessing of the impact of the SAT winding configuration on the distribution and propagation of the quench phenomenon. These activities are part of the analysis on the realisation methods of windings for superconducting devices with SAT tapes. In particular, the aim is to examine innovative winding methods, called NI (no-insulation), which do not require the use of electrical insulation between the layers of SAT tape that make up the device. These configurations, initially developed for the winding of superconducting magnets, can be used to realise superconducting devices for electrical power applications. Of particular interest is the application in SFCL devices, especially for both AC and HVDC (High Voltage Direct Current) grids. In this first phase, preliminary studies and tests were performed with the aim of developing the design and analysis methods of thermal quench induction systems in SAT tapes and windings and checking the feasibility and effectiveness of the proposed methodologies on simpler systems made on linear sections of SAT tape.

• Activity related to the European FASTGRID Project with studies and tests on prototype 2G SATs for SFCLs in HVDC power grids. THEVA’s GdBCO-based 2G SAT tapes, developed and produced within the FASTGRID project, have been subjected to a significant set of experiments in the RSE Superconductor Laboratory, which can be divided into: direct current (DC Direct Current) tests for the evaluation of the SAT critical current; alternating current (AC Alternate Current) tests for assessing of AC losses, the behaviour in the current limitation phase and the thermal stability of SAT.

For both of these types of tests, new measurement and numerical processing methods have been implemented which provide quantitatively and qualitatively better information than the techniques used previously.