HVDC System Refurbishment


ABB was awarded a contract by Societe nationale d’electricite (SNEL) to upgrade key technology on one of the longest electricity transmission systems, located in the Democratic Republic of Congo (DRC).

The Inga – Kolwezi HVDC Converter link, built in 1973, connects the hydro power resources from the Congo River to the mining district of Katanga in the south-east of the country. It also enables excess power to be exported to the Southern African Power Pool countries.

Project Solution

The HVDC system refurbishment included new thyristor valves, high-voltage apparatus and the MACH control and protection system. Refurbishment will extend the links life span, enhance the reliability of the DRC grid and ensure efficient transmission of hydro electricity across the region.

The refurbishment included:

  • New thyristor valves and valve cooling systems
  • New main circuit components in the AC harmonic filters
  • New main circuit components in the AC and DC switchyards
  • New MACH control and protection system
  • Refurbishment of synchronous condensers

PSC Services

PSC provided ABB with on-site management of all activities associated with commissioning of the new equipment installed as part of the refurbishment of the HVDC system.


Working in the DRC poses many challenges which had to be carefully managed to ensure a timely delivery of project milestones to the client. The extreme climate and difficult transport networks were some of the main challenges that had to be factored into the project planning.



PSC involvement in this project was completed upon successful commissioning of the majority of the upgrade scope. A full system testing of the enhanced converter link was carried out upon completion of a parallel project to replace the converter transformers, which was scheduled and completed in 2016.