Power System Characteristics of the SCFCL in Parallel With a Resistor in Series With a ZnO Device

Superconducting fault current limiters (SCFCLs) are expected to improve the reliability and stability of power systems. The 3-phase FCL system, which consists of 3 superconducting fault current limiters of transformer type in parallel with a resistor in series with a ZnO device, was proposed and its small model was designed and made. In a power system the FCL system is expected to limit the peak of the fault current inductively and also to consume the acceleration energy of the generators by means resistive component. The power system characteristics of the proposed FCL system was experimentally investigated by use of the model FCL and a laboratory scale power system simulator. The FCL system switches its impedance from inductive type (L-type) to inductive+resistive type (L + R-type) in a cycle due to the ZnO device. The peak of the fault current was limited in the L-type time interval and the energy was consumed in L + R-type interval. The proposed FCL system limited the fault current at the simulated fault and successfully recovered the stand-by mode in the model power system. At the same time, the energy consumption in the resistor reduced the accelerating energy of the generator and then improves the power system transient stability.