As part of the recent Uprating and Refurbishing Hydro Power Plants conference, held from 10-12 December 2001 in the Czech Republic, delegates were given a tour of the CEZ-owned Stechovice pumped storage power plant. Carrieann Davies shares some of the information gained on the trip
December may not seem like the best time to visit a hydro plant, particularly in the climate of the Czech Republic. But after persevering through the wind and snow we were treated to Czech utility CEZ’s hospitality and an interesting tour of its Stechovice plant.
Located on the Vltava river, Stechovice is split into two units – power generation and pumped storage. The Stechovice I hydro power station was originally built as the second station of the Vltava cascade at the end of World War II, between 1943-1944.
Controlled directly from the control centre at Stechovice, the 22.5MW power station is equipped as a classic run-of-river hydro power station, with two sets of Kaplan turbines with an installed capacity of 11.25MW each. It also includes an outdoor 110 kV substation, and outgoing and distribution transformers.
The reservoir of this medium-head hydro station is 9.4km long and reaches as far as the stilling basin of the Slapy hydro power station, also owned by CEZ. With a capacity of 11.2M m3, the reservoir’s predominant purpose is to balance the fluctuating runoff from the peak load hydro power station at Slapy. Along with the Vrané reservoir, it balances the runoff from the entire Vltava cascade. It allows for the peak load operation of the Slapy hydro power station, while it generates semi-peak load electricity.
The plant’s concrete dam with a granite revetment is 22.5m high and 120m long, with five spillways with crest gates. The spillways have a capacity of 2400m3/sec. According to the company, this will allow to plant to handle floods as catastrophic as the one the country experienced in 1890.
The 45MW Stechovice II pumped storage plant was commissioned in 1948, with rehabilitation work undertaken in 1996. The plant was originally designed with two pumped storage units of 20MW each. These were, however, taken out of operation during the rehabilitation works and a new shaft pumped storage unit was installed. According to the company, the new 45MW unit works more effectively, and takes only 100sec to get from still to full operation in order to generate electricity – 300sec to pump water. Pipeline for the plant is located 40m deep and has been kept as straight as possible.