The Inga-Kolwezi link (formerly the Inga-Shaba link) is a ± 500 kV, 560 MW HVDC power transmission system. This HVDC transmission line continues to deliver power despite instability in central Africa. The line's extreme length and difficult logistics resulted in a decision to build two monopolar lines with four switching stations. Converter stations were built so the two converter poles can be operated in parallel with ground return, in case of a monopolar line outage.
ABB signed a contract for the converter stations in 1973, but due to civil unrest in the country (formerly called Zaire), the transmission line was not put into service until 1982. The Inga-Kolwezi link is owned by DRC's national electricity utility, Société nationale d'électricité (SNEL).
Each valve hall is equipped with six air-cooled double valves, which at the time featured the highest valve voltage rating in the world. Each single valve has 258 series-connected thyristors.
ABB upgraded the link in 2009, installing new thyristor valves, high-voltage apparatus and its MACH control and protection system to extend the links life span, enhance the reliability of the DRC grid and ensure efficient transmission of hydro electricity across the region.
2017 ABB was entrusted to carry out another refurbishment that will boost transmission capacity, enhance grid reliability, extend life span and ensure the efficient transmission of hydro-electricity across the region. The retrofit will make it possible to increase transmission capacity from 520 megawatts (MW) to 1000 MW, securing power supplies to the mining region in Katanga and strengthening the power infrastructure in DRC. ABB’s project scope includes system studies, supply of key equipment such as high voltage apparatus and commissioning.