Risk Analysis and Upgradation of Protections for HVDC Project with Common Grounding Electrode

As an essential part of HVDC project, the grounding electrode provides path for the ground current and unbalanced current. HVDC projects in Southeastern China usually adopt the method of common grounding electrode, where two or more HVDC projects are connected to the same grounding electrode. A potential risk is that the common grounding site could provide the path and introduce ground current and unbalanced current to the other HVDC converter station, causing the protection system to respond unexpectedly. This paper carried out the verification through PSCAD simulation and provide protection upgradation method in a common-grounding HVDC system.