Fast-cycling, conduction-cooled, quasi-isothermal, superconducting fault current limiter

Abstract

Fault Current Limiters (FCL) provide protection for upstream and/or downstream devices in electric power grids. Conventional FCL require the use of expensive conductors and liquid or gas cryogen handling. Disclosed embodiments describe FCL systems and devices that use lower cost superconductors, require no liquid cryogen, and are fast cycling. These improved FCL can sustain many sequential faults and require less time to clear faults while avoiding the use of liquid cryogen. Disclosed embodiments describe a FCL with a superconductor and cladding cooled to cryogenic temperatures; these are connected in parallel with a second resistor across two nodes in a circuit. According to disclosed embodiments, the resistance of the superconducting components and its sheath in the fault mode are sufficiently high to minimize energy deposition within the cryogenic system, minimizing recovery time. A scheme for intermediate heat storage also is described which allows a useful compromise between conductor length enabled energy minimization and allowable number of sequential faults to enable an overall system design which is affordable, and yet allows conduction cooled (cryogen free) systems which have fast recovery and allows for multiple sequential faults.