Earthing requirements for HVDC systems

Following the recent developments in the field of power electronic valves, High Voltage Direct Current (HVDC) systems have become more attractive in power systems, and are widely recognised as a suitable tool for future power systems, especially in bulk power transmission over long distances. Grounding electrodes are an important part with significant roles in the operation of the HVDC systems. In this paper, first a brief review of different types of HVDC configuration is presented. Essential requirements in the design and operation of the HVDC grounding system are then presented and discussed. In the relevant studies, environmental impacts of HVDC electrodes, e.g. step voltage, effect on the buried metallic structures, DC magnetic bias of power transformers and mitigation methods are highlighted. Finally, a basic modelling of different physical configurations of HVDC electrode resistance is performed.