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

The engineering critical current, i.e., Ic, of 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. In addition, 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 recent years, several methods have been proposed, and many various techniques are now available. In this paper, we are interested to quantify the impact the enhancement of NZPV will have on the design of RFCLs based on HTS-CCs whichever is the adopted technical solution. For this reason, we use numerical models to analyze the effects of the NZPV enhancement on the limitation performance of an RFCL integrated in a medium-voltage power grid.