VSC-HVDC Bipolar Grid Based On Novel Distance Protection Scheme

Abstract

Mostly distance protection is widely used in HVAC system no practical implementation is done for HVDC system. It is essential to measure accurately difference in internal fault from external correctly in distance protection at the zone boundary. The smoothing reactor in HVDC system is present at two ends and it can be considered as the operating boundary of distance protection. Considering these feature this paper introduce distance protection method for HVDC transmission line. Current and voltage at end-point are planned accurately using those at the relay point, based on distributed parameter model. The line between the fault point and end point is simplified as RL model lumped parameter and differential equations obtain fault distance. In this way, accuracy of calculation at the zone boundary is attained, that contributes to the improvement in operation of protection. Simulation results show that proposed method is used as primary protection for HVDC transmission and is capable of protecting the whole line with high rapidity.