Transmission loss of prospective power transmission model system integrated under superconducting environment

We have developed a ''Prospective Power Transmission Model System Integrated under Superconducting Environment'', abbreviated to PROMISE, with the transmission capability of 6kV-1000kVA. The PROMISE consists of a superconducting transformer (SC-Tr), a superconducting fault current limiter (SC-FCL) and a superconducting power cable (SC-power cable). These components are cooled down at liquid helium (LHe) temperature, 4.2K, in a cryostat with a volume of 854 e. The paper indicates a computing procedure of a total heat leak P-leak into the cryostat and discusses transmission losses of the superconducting electric power system, which evaporate the LHe. P-leak, core loss P-core of the SC-Tr and a.c. loss P-ac in the superconductor were measured in the PROMISE to be 43W, 180W and 50W, respectively. The measured P-leak agreed with the theoretical one. In the superconducting power transmission system, the power to operate the refrigerator for liquefying the evaporated helium must be taken as the transmission loss. If the penalty factor was 500, the transmission loss was estimated to be 137kW and took 13.7% of the transmission capability in the PROMISE.