Coil Design of 200 MVA/200kV DC Superconducting Fault Current Limiter by Employing Iron Yoke

Abstract

With increase of direct current (DC) transmission voltage and capacity, the short-circuit fault current of DC transmission is one of serious difficulties in high-power DC system. In order to reduce the fault current, we propose a coil design method of a 200 MVA/200kV resistive DC superconducting fault current limiter (DC-SFCL). The target is to limit the short-circuit current to less than (1-35%) of the predicted value when the DC short-circuit occurs. However, the cost of DC-SFCL in high-power DC system is relatively high, which weakens the advantage of resistive DC-SFCL. For economic reasons, a pair of iron yokes is installed with the DC-SFCL limiting component, a superconductor coil, to alter the magnetic field and promote the utilization efficiency of YBCO CCs. We design two resistive DC-SFCLs without and with iron yokes for comparison for target limiting resistance 5 $\Omega$ . Influence of the iron yoke is investigated and discussed in 2-dimensional (2D) Finite Element Method (FEM) models by simulation. The simulation result shows that the proposed method is effective and economical.