The ultra high voltage direct current（UHVDC） project transfers huge capacity energy so that it must have high reliability.Many equipment are developed and produced for the first time without the operation experience.The reliability requirements on the converter transformer

valve

reactor etc are stricter than that of the normal HVDC project.This paper studies the operation experience of HVDC transmission project belonging to the State Grid Operation Company since 2000.Some methods are carried out to complete the UHVDC scheme and eliminate the potential problems

like the analysis on the EHVDC operation experience

the earlier control and prevention of major accidents

the similar problems and their regularities.The safe operation level of UHVDC pilot project can be increased in order to fulfill its transmission capacity

reduce the unnecessary blocking and maintenance time.