Temperature and Pressure Simulation of a 1.5-km HTS Power Cable Cooled by Subcooled With a Fault Current

Abstract

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 LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . 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 LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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 LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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 LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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.