Hybrid transfer switch with fault current limiting function

The transfer switch is one of the most useful devices for power quality improvement. The authors have been studying about the control scheme of a solid state transfer switch for faster and stabler operation, and a hybrid configuration with mechanical and semiconductor switch for lower conduction losses. On the other hand, distributed generators such as wind turbines, photovoltaic generators, micro turbines and fuel cells are coming into the load side. As a new power delivery system with such distributed generations, the Flexible, Reliable and Intelligent Electrical eNergy Delivery System (FRIENDS) is proposed. These situations make the fault current level of distribution networks higher and some fault current limiting devices are required in distribution systems. The authors propose to combine the fault current limiter with the hybrid transfer switch. Configuration of the system, detection method of faults, and experimental results to show the principle are presented.