Reliability and Availability Index Study of UHVDC System

UHVDC system of Jinsha river first stage transmission project has capability of 6 400MW each, with complicated main circuit arrangement and long distance transmission line, thus higher reliability availability requirements. At the sending end, three converter stations, including Xiangjiaba, Xiluodu left bank and right bank converter station are very close to each other. Consequently, DC fault in any UHVDC system will have impact on the rest other 2 systems, even the whole sending end AC system. For the receiving end system, 6400MW is a bulk transmission capacity, i.e. generation power for receiving end system. It can be anticipated undoubtedly that there will be large impact even the lose of monopole of UHVDC system. Therefore, reliability is an important item for UHVDC system, which should be given enough emphasis. In this paper, analysis was carried out on operating HVDC systems, such as 3GC, 3GG, Tian-Guang, etc trying to indicate the fault apparatus as well as ratio of overall fault time based on operating experience, fault statistics, reliability result of present HVDC system in China. Thus, the reliability availability index for UHVDC system was analyzed and proposed in this paper considering main circuit arrangement as well as project characteristics of UHVDC system.