Waseda University has developed computer programs to estimate the transient temperature and pressure distributions in a high-temperature superconducting (HTS) power cable cooled by a forced flow of subcooled LN2. This simulation is crucial for realizing a practical HTS power cable to assess the effects of short-circuit accidents. When a short-circuit accident occurs, a fault current of 31.5 kA with a duration of 2 s may flow in a cable in the worst case, which is the Japanese criterion for a 66-kV transmission line. The temperature profiles of the LN2 coolant and cable cores were analyzed by solving the heat conduction and heat transfer equations using a finite-difference method. The pressure profiles of the LN2 coolant were calculated using Fanning's equation. For practical use, it was assumed that HTS cables that are a few kilometers long will be adopted. In this study, an evaluation of the stability of a 1.5-km HTS cable with a fault current of 31.5 kA over 2.0 s was performed using our computer program. According to the results, the temperature of the LN2 coolant at the outlet reached the saturation temperature after the fault, and vaporization suddenly occurred. The evaporated gas was released from the outlet to the terminal.
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