Opportunities for High-Voltage AC Superconducting Cables as Part of New Long-Distance Transmission Lines

The purpose of this study is to compare possible superconducting 380-kV cables with existing overhead lines and underground cables. The study compares the required corridors and energy losses of different versions of a 1.7-km transmission system with a power of 6.6 GVA. Comparison covers the following setups: 4 × 380 kV high-voltage overhead lines, 8 × 380 kV conventional cables, 2 × 380 kV and 4 × 380kV superconducting cables with warm and cold dielectrics. The paper will present the description of the different setups as well as the calculation of energy losses. The required widths of the underground cable corridors are also considered in this study. Finally, the temperature profile and pressure drop of the superconducting cables are investigated. The main results can be summarized as follows. 1) For the assumed voltage level and power, overhead lines require a corridor width of 70 m, whereas a corridor of less than 7.7 m in width is necessary for superconducting 380 kV cables. 2) The 380-kV superconducting cable reduces the energy loss by approximately 8100 MWh per year in comparison to the conventional overhead lines. This yields a feasible energy loss reduction of up to 75%.