Temperature Simulation of a 20 m HTS Power Model Cable System in a Fault Current for 275 kV Transmission Lines

A simulation has been developed for estimating the transient temperature and pressure distributions in a high-temperature superconducting (HTS) power cable with a fault current accident cooled by a forced flow of subcooled liquid nitrogen (LN₂). This simulation is an essential tool for realizing a practical HTS power cable in order to assess the effects of short-circuit accidents. When a fault occurs in a 275 kV class power transmission system in Japan, an excessive current of 63 kA may flow in the cable for 0.6 s. When faults occur, it is important to estimate the temperature and pressure profiles in a cable cooled by the forced flow of subcooled LN₂. The temperature profiles of the LN₂ coolant and the cable cores were analyzed by solving nonlinear partial differential equations of the heat transfer phenomenon through heat conduction using finite-difference method. The GASPAK software package (Cryodata) was used to evaluate the fluid properties. The simulation results for 275 kV class 20 m model cable show fairly good agreement with the experimental results obtained by Fukukawa Electric.