The most advanced solution is the HVDC Supergrid, nevertheless fault currents mitigation in DC grids remain an issue: even if DC circuit breakers have emerged, they are not satisfying, whereas Superconducting Fault Current Limiters (SCFCLs) using High Temperature Superconducting (HTS) REBCO tapes bring an attractive solution. SCFCLs have already proved their outstanding performances in medium voltage AC systems, with a few commercial devices in service. However, present REBCO conductors cannot be readily used at very high voltages: the electrical fi eld under current limitation is too low and leads to too long tapes and high cost. FASTGRID aims to improve and modify the REBCO conductor, in particular its shunt, in order to signifi cantly enhance (2 to 3 times) the electric fi eld and, at the same time, the economical SCFCL attractiveness.

A commercial tape will be upgraded to reach a higher critical current and enhanced homogeneity as compared to today’s standards. For the sake of a safer and better operation, the tape’s normal zone propagation velocity will be increased by at least a factor of 10 using the patented current flow diverter concept. The shunt surface will also be functionalized to boost the thermal exchanges with coolant. This advanced conductor will be used in a smart DC SCFCL module (0.5/1 kA and 30/50 kV). This one will include new functionalities and will be designed as sub-element of a real HVDC device. In parallel to this main line of work, developments will be carried out on a promising breakthrough path: ultra-high electric fi eld tapes based on sapphire substrates.

FASTGRID will bring this to the next levels of technology readiness. In conclusion, FASTGRID project aims at improving signifi cantly existing REBCO conductor architecture to make SCFCLs economically attractive for HVDC Supergrids. Moreover, availability of such an advanced conductor will have an impact on virtually all other applications of HTS tapes. Cost effective FCL using advanced superconducting tapes for future HVDC grids FASTGRID.