High Voltage Calculations for a 380 kV Superconducting Fault Current Limiter

Increasing fault current demands for future high voltage grids may not only exceed technical feasible limits for current breaking but they may have also strong impact on system costs if all components of the affected network must be designed or replaced for such increasing stresses. Superconducting fault current limiter technology may deliver a cost effective alternative by keeping the fault currents within common values. For the 380 kV voltage range such fault current limiters are supposed to be designed for similar high voltage test values and waveforms as power transformers of this grid level. In combination with a superconductor tape length of about 100 km per phase, it can be expected that 380 kV superconducting fault current limiters for one phase have sizes similar to 3-phase 380 kV power transformers. In this article, field limit estimations were done for the different insulation materials since experimental data with high voltage of several 100 kV or above 1 MV are rare or still missing for the assumed cryogenic temperature and pressure range. A principle high voltage design for one phase of a 380 kV/5 kA superconducting fault current limiter was performed based on these maximum field values. The design includes capacitor bushings and post insulators.