Abstract:

Based on the operation and maintenance of AC/DC hybrid systems in China Southern Power Grid, the statistic analysis was carried out on the multiple DC commutation failures caused by AC fault. Then, the influence of AC fault on the weak links of DC system, such as converter valve, valve cooling system, DC protection, was summarized. From the actual conditions of operation and maintenance, the preliminary improvements were suggested according to the specific effect, which were not only valuable for improving the operation and maintenance capability and insuring the safe and reliable operation of AC/DC system, but also could provide useful references to the design and construction of DC transmission projects in the future.

Key words: AC system, commutation failure, multiple DC, voltage fluctuation, valve cooling system