Coordination of Superconductive Fault Current Limiters With Zero-Sequence Current Protection of Transmission Lines

A 500 kV saturated iron-core superconductive fault current limiter (SISFCL) has been designed to be installed in an extra high voltage (EHV) transmission system in southern China. We carried out studies on compatibility and coordination problems in the application of this kind of device in an EHV network. In this paper, the operational principle of an SISFCL and the protection configuration of transmission lines are briefly introduced. The influence of an SISFCL on the zero-sequence current protection of the grid, taking into consideration both the fault of SISFCL itself and fault of the power lines, is discussed. In order to coordinate the SISFCL and the grid protection scheme, requirements and recommendations are proposed. A model of a 500 kV double-circuit transmission system with SISFCLs is built using Electromagnetic Transient Program including DC (EMTDC) software package. The simulation results are in good agreement with the theoretical analyses.