Progress on the R&D of fault current limiters for utility applications

Mechanical and thermal stresses caused by short-circuits are a major design criterion of electric power systems. Conditional impedance increase during a fault from new fault current limiter (FCL) devices can reduce short-circuit current levels significantly without adding additional impedance during normal operation. This paper updates on the present R&D status of new FCL technologies. At present, superconducting FCLs (SCFCLs) are being introduced commercially after first field tests of medium voltage demonstrators showed the technical feasibility. Different types of SCFCLs and non-superconducting FCLs have been developed in order to best fit the specific application requirements. Several FCL projects are investigated in order to illustrate and discuss the progress on the way to meet the two major R&D objectives: developing high voltage SCFCLs (Gt100 kV) and producing simple and low cost SCFCLs for medium voltage levels (6-36 kV).