Toshiba, Voith, ABB to repair Bulgaria’s Chaira pumped storage hydropower plant

Bulgarian state-owned power utility NEK signed contracts with Toshiba, for the repair of unit 1 of the Chaira pumped storage hydropower plant, and with the consortium Voith-ABB for unit 3. Generators in units 1 and 4 need to be replaced because of extensive damage that they suffered three years ago.

Following the completion of tests, National Electricity Co. (NEK), part of government-controlled Bulgarian Energy Holding (BEH), put the unit 2 of the Chaira system back into regular operation at the beginning of the year. Now the utility made another crucial step to fully repair the largest pumped storage hydroelectric plant in Southeastern Europe.

The facility with a nominal 784 MW in pumping capacity and 864 MW for generating electricity went completely offline in May 2022. Namely, it has crashed several times, partly due to unsuccessful rehabilitation efforts.

Toshiba built first two units in 1995

NEK signed a contract with Japan-based Toshiba, the original manufacturer, for the repair of unit 1, which will ensure its safe operation in the medium term, the Ministry of Energy said. It said the works would commence as soon as possible, to get the generator back online next year. Minister Vladimir Malinov and Ambassador of Japan Hisashi Michigami attended the event.

Toshiba installed units 1 and 2, three decades ago. The construction of the other two, using the same technology, was completed in 1999. Reversible turbines 1 and 4 are beyond repair, so they need to be replaced. NEK published a joint tender in September.

Austrian consortium comprising Voith, which repaired unit 2, and ABB signed the deal for the rehabilitation of unit 3. The ministry said the contractors would apply a similar special engineering solution. NEK has already dismantled the generator.

Bulgaria envisaged expansion of Chaira capacity

Chaira is part of the Belmeken-Sestrimo-Chaira hydropower complex, Bulgaria’s largest. NEK rehabilitated the Belmeken pumped storage hydroelectric plant last February. It consists of five units with 373.5 MW in generation capacity. Two are reversible, enabling 104 MW in pumping mode.

Bulgaria’s third existing pumped storage hydropower system is called Orphey. Installed inside the Vacha dam in the country’s south, it comprises four turbines with just under 164.8 MW in total. One unit can work both ways, where the pumping mode capacity is 47.4 MW, NEK’s data shows.

In addition, it is developing projects for two pumped storage hydropower plants. According to Bulgaria’s draft energy strategy until 2053, Chaira’s capacity will be expanded.

Notably, the Ministry of Energy has earmarked massive grants for different types of battery energy storage systems (BESS). It is another strategic move aimed at accommodating new renewables. However, Bulgaria has troubles with European Union funding due to an almost continuous political crisis that began three and a half years ago.