Numerical simulation on fault current condition in 66 kV class RE-123 superconducting cable

The new Japanese national project of development of 66 kV/5 kA high-temperature superconducting (HTS) power cables has been started since 2008. In an AC power system, a fault current may flow in the event of a short circuit accident. The maximum fault current condition is defined to be 31.5 kA _rms for duration of 2 s for 66 kV class transmission line in this project. Therefore, one of the technical targets in this project is to design the HTS power cable to survive at this fault current condition. The coated conductors have copper layer as a stabilizer not to be damaged by over-currents. The HTS cable has a copper former and copper shield layers in parallel with the HTS conductor layers and HTS shield layers, respectively, to control the temperature rises in the HTS cable at a fault accident. In this study, we simulated the maximum temperature rises in the HTS power cable at the fault current condition of 31.5 kA_rms for 2 s in order to design the copper stabilizer and copper shield layers by using a computer program we developed on the basis of 3D finite element method (FEM) and electrical circuit model.