Summary of HVDC Grounding Electrode and Related Issues

Basic concepts of grounding are introduced in this paper.The earth current,the step voltage,the maximum allowable temperature rise and the grounding electrode life of high voltage direct current(HVDC) are analyzed.Main issues involved in designing HVDC grounding electrode are stated,such as soil resistivity test,grounding electrode type selection,and calculation of grounding parameters.The impact of HVDC grounding electrode on DC bias in transformer is expounded,and the corresponding suppression measurements are presented,such as the use of deep grounding technology,series capacitors at the AC outlet of transformer and installation of devices for DC current suppression at the neutral point of transformer,etc.Finally,the common grounding mode of HVDC transmission system is discussed.