Zambezi (previously Caprivi) Link HVDC Interconnector: Review of Operational Performance in the First Five Years

摘要

The Zambezi Link HVDC Interconnector (previously named Caprivi Link HVDC Interconnector), located in Namibia, was put into commercial operation in October 2010. The monopole scheme rated at 300MW connects the electricity networks of Namibia and Zambia. The scheme utilises Voltage Sourced Converters (VSC) and was the first scheme to use VSC technology with overhead lines. The Zambezi 330 kV substation is connected to Gerus 400 kV substation via 952 km of overhead line operating at -350kV dc. The Link has been designed to allow for a future bipole extension with a final rating of 600MW in conjunction with ac network strengthening. The Zambezi Link HVDC scheme is an important regional interconnection in the Southern African Power Pool. The scheme has been in operation for more than 5 years since commissioning and this paper reports on the operational performance of the scheme during this time. The scheme connects two very weak ac networks that have a high possibility of transferring to islanded/passive networks. The scheme was designed with special control and protection functions such as transfer to passive/island operation and a dc line fault clearing scheme for VSC. The performance of the scheme in response to actual network events, and the operational experience of the dc line fault clearing scheme are presented. The paper also presents the Reliability, Availability and Maintainability (RAM) performance of the scheme and reports on the performance of the test earth electrodes.