Design and Performance Test of a 20-kV DC Superconducting Fault Current Limiter

A resistive-type dc superconducting fault current limiter (SFCL) is developed for the fault current limiting at the Suzhou Nami substation. The rated voltage and current are 20 kV and 400 A, respectively. The prospective peak value of the short-circuit current is about 3.5 kA, and the current could be limited to less than 2.1 kA by the SFCL. The SFCL uses about 1800-m stainless steel reinforced yttrium barium copper oxide (YBCO) conductor. According to the testing results, the developed SFCL has passed the dc withstand voltage test at 50 kV/min, the full-wave lightning impulse voltage at 95 kV, and the dc power switching test with a peak value of 2.26 kA and a fault duration of 16.5 ms.