A New Topology of Fault-current Limiter and its control strategy

In this paper a new type of fault current limiter based on DC reactor with using superconductor are presented. In normal operation condition the limiter has no obvious effect on loads. When fault happens, the bypass AC reactor and series resistor 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 an inverter and is closed as soon as possible. Subsequently the fault current is fully limited by the bypass AC reactor and series resistor. The magnitude of L_ac and r_ac must be equal with protected load. By using the electro-magnetic transients in DC systems which are the simulator of electric networks (EMTDC) software we carried out analysis of the voltage and current waveforms for fault conditions. Waveforms are considered in calculating the voltage drop at substation during the fault. The analysis used in selecting an appropriate inductance value for designing