Multi-terminal HVDC and DC-grid technology

The multi-terminal high voltage direct current (HVDC) and DC grid technology based on the traditional HVDC and voltage sourced converter HVDC (VSC-HVDC) is one of the valid approaches which can resolve the problems of renewable energy integration in China. The background of the development of the DC transmission was analyzed and the two-terminal HVDC technology was overviewed in this paper. The basic concepts of the multi-terminal HVDC and DC grid were discussed. Combined the differences and relations between them, and their respective characteristics, the key technical issues to be resolved, cause of these problems and the research progress of building the DC grid in future were indicated, from which the thoughts and suggestions for the DC grid technology direction were put forward.