The refurbishment of Unit 2 at the Chaira pump-storage hydropower plant has been successfully completed, featuring a groundbreaking turbine modification that is unique on a global scale. The 12-month intensive repair process has significantly improved the facility’s security and efficiency, enabling it to once again play an active role in the country’s electricity grid. A similar refurbishment approach will be applied to Unit 3, with work expected to be completed by the end of 2025.
Meanwhile, the National Electricity Company (NEK) is in ongoing discussions with Toshiba, the original equipment manufacturer, for a medium-term solution to repair Unit 1. These talks are in line with the Memorandum of Cooperation signed in September between Bulgaria and Japan. Toshiba is expected to finalize and sign the agreement by the end of the year, which would allow for the operation of two additional units at the region’s largest pump-storage HPP by early 2026.
The refurbishment of Unit 2, which has already resumed operations, involved the rehabilitation and installation of the generator stator and turbine. After successful testing, the facility is expected to be fully operational by early 2025. This refurbishment marks the first major overhaul of the plant’s control and management systems, as well as key turbine components, since the plant’s initial construction.
Located beneath the Belmeken dam, the Chaira pump-storage HPP is the largest underground power station in the Balkans, with an installed capacity comparable to one unit of the Kozloduy nuclear power plant. The facility had been offline since March 2022 following an incident during post-rehabilitation testing.
