Series Transformer-Based Solid State Fault Current Limiter

This paper studies a novel transformer-based solid state fault current limiter (TBSSFCL) for radial distribution network applications. The proposed TBSSFCL is capable of controlling the magnitude of fault current. In order to control the fault current, primary winding of an isolating transformer is connected in series with the line and the secondary side is connected to a reactor, paralleled with a bypass switch which is made of anti-parallel insulated gate bipolar transistors. By controlling the magnitude of ac reactor current, the fault current is reduced and voltage of the point of common coupling is kept at an acceptable level. Also, by this TBSSFCL, switching overvoltage is reduced significantly. The proposed TBSSFCL can improve the power quality factors and also, due to its simple structure, the cost is relatively low. Laboratory results are also presented to verify the simulation and theoretical studies. It is shown that this TBSSFCL can limit the fault current with negligible delay, smooth the fault current waveform, and improve the power quality.