A new proposal for solid state fault current limiter and its control strategies

A novel topology of solid state fault current limiter (SSFCL) is presented for medium- and high-voltage electric network in This work. In normal operation condition the limiter has no obvious effect on loads. When fault happens, the bypass AC reactor will insert the fault line automatically to limit the short circuit current, when the control circuit detects a short circuit fault, the solid state bridge in fault line works as a inverter and is closed as soon as possible. Subsequently the fault current is fully limited by the bypass AC reactor. Because the parameters of the solid state devices and DC reactor are not determined by short circuit current rating of the network, it is flexible to design. The proposed single-phase SSFCL is numerically tested. It is shown that the single-phase bridge is closed at the current across zero just like as a soft-switch, and there is no oscillation as well as overvoltage excited by the SSFCL when the fault current is switched off. The control mode is simple and facile. It proved that the theoretical prediction and the current limiting performance is satisfactory for research and development.