Recovery characteristics of YBCO tapes against DC over current impulse

Abstract

With the fast development of voltage source converter based high voltage direct current (VSCHVDC) power system, an effective fault current method is in demand. In HVDC systems, the short-circuit current generally exceeds the capacity of the fast circuit breaker. Meanwhile, a superconducting fault current limiter (SFCL) is able to limit the short circuit current level. If installed in an overhead line system, SFCL has to meet the requirement of the reclosing time. The fault current is much larger than the critical current of superconducting tapes, which generates huge heat and the temperature of the tapes in the resistive type SFCL will increase sharply. After removing the fault, the tapes need certain time to recover to the superconducting state. Thus, the recovery characteristics in DC faults are an important feature of the resistive type SFCL, and they are mainly determined by the corresponding features of the superconducting tapes. In this paper, a method is presented to measure the recovery time under transient DC over current impulse. The recovery characteristics of high temperature superconducting (HTS) tapes under transient DC over current impulse are studied. The recovery time under different impulse duration and different impulse amplitude are measured by experiments. The influence factors of the recovery characteristics are discussed, which will be useful for the design of SFCL.