By combining the merits of the line commutation converter based HVDC(LCC-HVDC)and the voltage source converter based HVDC(VSC-HVDC)

we have the hybrid high-voltage direct current(HVDC)transmission system that is a new topology of HVDC. A comprehensive technical analysis is made of hybrid-HVDC including the main circuit design

converter topology

control and protection system

to point out the technical barriers and future development directions. An overview of the application and status quo of hybrid-HVDC projects across the world is also given. With an eye to China's energy development strategy

characteristics and demands of future grid advancement

the research and engineering application trend of hybrid-HVDC projects is demonstrated

which shows that the hybrid-HVDC technology has a critical role to play in the future grid arena.