Abstract

One promising device for fast, automatic and fail-safe limitation of short-circuit currents is a resistive type SFCL. Since the first successful field test of a resistive type SFCL in 2004 in Germany several prototypes have been built and tested successfully worldwide with voltages up to 220 kV. Medium voltage SFCLs have been operated in the grid for several years but so far, no 380 kV resistive type SFCL exists.
This study investigates the technical and economic feasibility of a 380 kV, 5 kA resistive type SFCL and proposes a feasible design. Based on the key requirements of the TSO, approximately 200 km of a 10 mm wide HTS tape with a critical current of 700 A at 77 K are needed for a three phase limiter. With this, a feasible design of the current limiting modules is shown. The detailed high voltage design considers all important components like e.g. the bushing and the cryostat and includes investigations of the non-linear voltage distribution inside the limiter. It is shown that a cryostat with a diameter of appr. 4 m and a length of appr. 14 m can fit all modules. Cooling is provided with liquid nitrogen at 77 K with a pressure of 5 bar and a closed as well as an open cooling system is possible.
It can be concluded that a 380 kV, 5 kA resistive type SFCL is feasible and that a dedicated R&D program is recommended to develop critical items, like the high voltage bushing and the current limiting module.