The Slapy Hydroelectric Power Station

The Slapy Hydroelectric Power Station was the first large project of the Vltava Cascade after the World War II. A 65 m high concrete gravity dam was built, forming an artificial lake that contains 270 million m3 of water, covers 14 km2, and is 44 km long, reaching as far as the stilling basin of the Kamýk hydroelectric power station.

The Slapy Hydroelectric Power Station was the first large project of the Vltava Cascade after the World War II. A 65 m high concrete gravity dam was built, forming an artificial lake that contains 270 million m³ of water, covers 14 km², and is 44 km long, reaching as far as the stilling basin of the Kamýk hydroelectric power station. In addition to power engineering significance, the large retention reservoir assists the regulation of the Vltava River’s water regime. The area is also favoured for summer recreation by inhabitants of the capital Prague.

The fully automatic power station generates peak-load electric energy, and participates in the output balance regulation of the national power system. It is able to reach full load in 136 seconds, and its output is remotely regulated from the control centre at Štěchovice, according to the power system’s needs. The fluctuating runoff from the Slapy hydroelectric power station is balanced by the Štěchovice and Vrané water reservoirs.

The Slapy water reservoir was built between 1949 and 1955. The reservoir is situated in a narrow defile at the end of the former Svatojánské proudy (St. John’s Streams) and used an original design. The entire power station is located in the very body of the dam. Under the four 15 m x 8 m spillways with 3,000 m³/s capacity are the machine room, all the supporting shops, administrative rooms, a 110 kV switch room, a 22 kV switching station, all the transformers and two bottom outlets.

The hydroelectric power station, put into operation between 1955 and 1956, is equipped with three sets of Kaplan turbines for a 56 m head. The water is brought to the turbines by three steel pipelines embedded in the concrete of the dam. The intake has steel quick-operating closing valves and temporary barriers. The generated electricity with 10.5 kV voltage is carried through transformers to the 110 kV switching house inside the dam. The electricity is then carried by cables through an inclined shaft up the dam to the portals above the headwater level. The 22 kV switching station is located and operates similarly.

See the movie about hydropower plants on the river Vltava