Research On The Influence Of Sharing Earth Electrode On ±800kV UHVDC Transmission Systems

Combining the feasibility study results of UHVDC project from Xiangjiaba to Nanhui, the connection modes of sharing earth electrode are analyzed. Sharing earth electrode by three UHVDC system rectifiers or inverters are studied respectively by electromagnetic transient analysis software EMTP-RV based on the main parameters of±800kV HVDC project from Xiangjiaba to Nanhui. This paper analyzes the different operation modes of the UHVDC system sharing earth electrode from the aspect of power system stable operation and transient operation. The merits and demerits of sharing earth electrode are summarized in detail. The feasible suggestions for the corresponding control and protection of UHVDC system sharing earth electrode are put forward.The simulation results show that the scheme of sharing earth electrode is feasible. However, the resistors of both the earth electrode and earth electrode line should be restricted within a certain range. In addition, there are very strict requirements for choosing the location to bury the earth electrode and designing the shared earth electrode itself.