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

Abstract

Abstract-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.

Multi-scale model of resistive-type superconducting fault current limiters based on 2G HTS coated conductors

“…where T 0 is the temperature of the liquid nitrogen bath, T c is the critical temperature of the (RE)BCO superconductor, and J c 0 is the critical current density in self-magnetic field at = T T 0 . We chose not to include the effect oftemperature on n, as proposed in [23]. However, this is by no means a limitation of the model: any n T ( ) model could be used, such as that in [24] or any better flux flow model to be proposed in the future.…”

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“…The temperature dependent critical current can be calculated according to (5) while the temperature dependence of the transition index is calculated according to (6) where T c is the critical temperature and T ref is a reference temperature. I cref and α cref are the critical current and transition index measured at a reference temperature while the indices k and β describe the nature of the temperature dependence for the critical current and transition index respectively [29].…”

Understanding the impact of failure modes of cables for the design of turbo-electric distributed propulsion electrical power systems

“…These locations then have to absorb a disproportionate amount of energy which can result in thermal take-off and localized damage over a short period of time [7]. Due to the relatively high heat capacity of HTS (compared to low temperature superconductors), the spread of the normal resistive area during a quench is in the order of cm/s, increasing the likelihood of damage from hotspots [8]. Improving the normal zone propagation velocity following a quench will be important in ensuring the stability of superconducting components.…”