Impact of the Normal Zone Propagations Velocity of High Temperature Superconducting Coated Conductors on Resistive Fault Current Limiters

The engineering critical current (Ic) of the high temperature superconducting coated conductors (HTS-CCs), today available on the market, is not a uniform parameter and varies significantly along the length of the conductors. Moreover, commercial HTS-CCs have a low normal zone propagation velocity (NZPV). This property, together with the Ic inhomogeneity, exposes the HTS-CCs to local thermal instabilities. A crucial challenge for the design of resistive fault current limiters (RFCLs) based on HTS-CCs is to avoid the thermal runaway of the conductors, and in this respect the enhancement of the NZPV is a promising solution. In the recent years, several methods have been proposed and many and various techniques are now available to enhance the NZPV. Whichever will be the best technical solution to improve NZPV of HTS-CCs, our aim is to quantify the impact the enhancement of NZPV will have on the design of RFCLs based on HTS-CCs. For this reason, we used numerical models to analyze the effects of the enhancement of NZPV on the limitation performance of a RFCL integrated in a medium voltage (MV) power grid. In this manuscript, we quantify the benefits the enhancement of the NZPV will have on the next generation of HTS-CC-based RFCLs for MV grids