Effects of a flux-coupling type superconducting fault current limiter on the surge current caused by closed-loop operation in a 10 kV distribution network

• A flux-coupling type SFCL is suggested to suppress the surge current caused by closed-loop operation.
• The suggested SFCL′s performance is assessed in a real 10 kV distribution system.
• The suggested SFCL can improve the system′s robustness against the surge current.
• Technical discussion regarding the practicability of experimentally building the suggested SFCL is conducted.

Due to the continually expansion in size of electricity distribution networks, the demand for the reliability of power supply is on the increase, and in the case of transferring load, a closed-loop operation is usually needed. However, in the course of the closed-loop operation, a larger surge current may be induced, and this current can cause the equipped over-current protection take action incorrectly. In this paper, a flux-coupling type superconducting fault current limiter (SFCL) is suggested to suppress the surge current caused by the closed-loop operation. The structure and principle of the suggested SFCL are introduced, and considering the SFCL′s current-limiting impedance, the mathematical process for calculation of the surge current is presented. Furthermore, according to the simulation analysis of a practical 10 kV power distribution network integrated with the SFCL, the surge current′s dynamic characteristics and the SFCL′s performance behaviors are both assessed. From the demonstrated results, the SFCL′s positive effects on reducing the surge current and improving the system′s robustness against the closed-loop operation can be verified. At the last of the paper, a few technical discussions regarding the SFCL′s engineering application are conducted, and some useful conclusions related to the practicability of experimentally building the SFCL are obtained. PACS codes: 85.25.Am; 84.30.Jc.