Design of UHVDC earth electrode

Based on the differences between UHVDC system and HVDC system, this paper introduces the new safety requirements of UHVDC earth electrode, elaborates the design process of UHVDC earth electrode and emphatically analyzes two design requirements: the maximum allowable step potential and the maximum allowable temperature. Analysis indicates that step potential in previous HVDC earth electrode design is quite strict and not suitable for the situation, the new standard is proposed. In addition, the body size of UHVDC earth electrode is unlike the previous HVDC earth electrode mainly limited by thermal stability, but is decided by step potential limits.