Research on the Design of Operating Condition of Multi-Resistance Superconducting DC Current Limiter

  Introduction  The working principle of the resistive superconducting current limiter is based on the zero resistance effect of the superconductor, which is connected in series in the line and basically has no resistance during normal operation. When the circuit is short-circuited and the current exceeds the critical current, the superconductor loses excess and the resistance value increases rapidly, which plays a role in limiting the short-circuit current. So the superconducting DC (Direct Current) current limiter has little effect on the power grid when it is in normal operation. When the system short-circuit current exceeds the critical current, it will quickly limit the current value, effectively reducing the requirements for DC equipment. Based on Nan'ao ±160 kV multi-terminal VSC-HVDC (Voltage Source Converter Based High Voltage Direct Current) system, the possible operating conditions of superconducting DC current limiter are discussed, and how to realize the possible operating conditions is analyzed.

  Method  For the five possible operating conditions, it was recommended to set disconnector to achieve automatic switching of operating conditions.

  Result  The proposed scheme of electrical connection and compact layout is given based on the configuration of the equipment. And according to different operating conditions, the corresponding current path diagram is given.

  Conclusion  The possible working conditions of superconducting DC current limiter and the automatic switching electrical connection and compact layout can be obtained by similar analysis for other flexible DC transmission systems.