Štěchovice pumped-storage plant in Czechia back in operation after three-month upgrade

The Štěchovice pumped-storage plant is back at full capacity after a three-month upgrade. Technicians replaced its control system and electrical protection systems. Energy workers also used the outage to carry out comprehensive maintenance on the normally inaccessible, more than half-kilometre-long penstock leading to the turbine, ČTK was told today by ČEZ spokesperson Martin Schreier.

The Štěchovice II pumped-storage plant is an important source of reserve power. It can reach full output within three minutes and supply the grid for four hours at the output of a smaller gas-fired power plant, helping to stabilise the Czech energy system.

„To guarantee that it continues to operate reliably in the years ahead, we have to keep it in excellent condition. In recent weeks, we have managed to replace the plant’s brain – its control system and electrical protection systems,“ said Róbert Heczko, director of ČEZ’s hydropower plants.

Energy workers also used the outage to carry out thorough maintenance on the water passages, which repair crews cannot access during normal operation. They inspected the more than half-kilometre-long penstock from the upper reservoir to the turbine, repaired wear on the turbine runner, which has a diameter of 2.2 metres, inspected the compressed-air equipment and carried out diagnostics and maintenance on the electric generator and transformers.

The Štěchovice pumped-storage plant has been in operation since 1947, when it was among the largest facilities of its kind in the world. Under ideal conditions, 27 cubic metres of water per second flow through the half-kilometre-long penstock from the upper reservoir to the generating unit; in pumping mode, the flow is 21 cubic metres in the opposite direction. Another notable feature is the floating solar power installation on the surface of the upper reservoir at Homole.