Insulation design of direct current resistive type superconducting fault current limiter

DC resistive type superconducting fault current limiters (SFCL) can be used in multi-terminal DC systems for fault current limiting. They help DC circuit breakers interrupt fault current with lower interruption overvoltage and they improve the interruption reliability. Insulation design is necessary for the application of SFCLs. The objective of this paper is to design the insulation of DC resistive type SFCLs. Firstly, Finite Element Method (FEM) is used to simulate the electric field distribution and magnetic field distribution in the SFCL. The simulation result shows that the strongest electric field is between the superconducting coils and the dewar vessel. Secondly, Bubble generation inside of SFCLs is analyzed, and so is the subcooled effects. The arrangement of the superconducting coils and the dewar vessel is optimized to achieve a good insulation ability, considering the insulation degradation caused by bubbles. A bubbles shield is suggested to put between the superconducting coils and the dewar vessel. Besides, a vertical arrangement of the superconducting coils shows a better insulation ability than horizontal arrangement. Finally, a 10 kV DC resistive SFCL is designed.