Current Limiting with Liquid Arc for HVDC Circuit Breaker

Multi terminal grid HVDC(MTDC) is important from the point of stability of electric power system with renewable energy power generation. Our new concept for HVDC-CB with the hybrid structure of the current limiter and the mechanical switch has been researched. Higher arc voltage in liquid arc (than gas or vacuum) is used for direct current limiting in the current limiter. The mechanical switch plays a role for final current interruption and insulation after interruption. Arc voltage characteristics in liquid arc stabilized with resin tube in some liquid materials (water, silicon oil, hydro fluoroether…). The arcing voltage more than 3kV was obtained with only 50mm gap. Fault current interruption in 10kV HVDC transmission system was simulated in EMTP/ATP with the new concept HVDC-CB using measured arc voltage. In conclusion, arc voltage more than five times of the measured value is necessary for successful interruption with enough limiting effect. Further research will be performed for improvement of liquid arc voltages and necessary time for interruption.