A Novel Protection Method for Grounding Electrode Line of UHVDC Based on Injection Current

In view of the Ultra High Voltage Direct Current (UHVDC) grounding electrode line protection based on injection method, this paper analyses the performance deficiency of the conventional protection scheme due to dead zone, and puts forward a new protection scheme of grounding electrode line. The new uses the head-end high frequency measured impedance transverse difference ratio to create the protection criterion, which only depends on the unilateral electrical quantity rather than on the communication channel. The proposed scheme greatly shortens the protection dead zone. In this paper, a simulation model was established using PSCAD/EMTDC based on the example of a certain ±800kV UHVDC system to validate the proposed protection scheme. Simulation results showed that the proposed protection of the new protection scheme proposed in this paper could greatly reduce the dead zone protection compared with the conventional protection scheme.