The Dalesice Pumped-Storage Hydroelectric Power Station

The Dalešice waterworks was built as a part of the nearby Dukovany Nuclear Power Station project. It includes the Dalešice water reservoir with the capacity of 127 million m³ of water, the Mohelno equalization basin, the Dalešice Pumped-Storage Hydroelectric Power Station, and the Mohelno run-off-river hydroelectric power station.

The Dalešice water reservoir is also used for a recreational purposes, fish breeding, improving flow of water in the river in dry seasons. However, the Dalešice water reservoir is namely a source of process water for the Dukovany Nuclear Power Station. It creates necessary head and water volume for operation of the Dalešice pumped-storage hydroelectric station, and it balances the water flow in the Jihlava River in the long run. It reduces the flood peaks on the lower course of the Jihlava River, and also the sedimentation of impurities from the upper part of the river and from the waste water from the nuclear power station.

The reservoir’s positive influence on the quality of water in the river shows in the presence of crayfish and trout under the Mohelno equalization basin. The power station functions as an energy accumulator; it generates electricity during on-peak periods and consumes it during off-peak periods of surplus. Its installed capacity of 450 MW and an ability to reach full load operation in just 60 seconds makes it an important participant in the output regulation of the national power engineering system, and an immediately available emergency reserve. It is, therefore, fully automatic and remotely controlled from the control centre in Prague.

The Dalešice water reservoir was built between 1970 and 1978. It has a 100 m high clay-sealed rock-fill dam with hydro-technology for handling flood water and for draining the reservoir. The water is brought onto the turbines by four steel pipelines which connect the station with the intake point. The turbines are closed with hydraulic butterfly gates. The hydroelectric power station and the switching station are located at the heel of the dam.The intake and outlet are fitted with trash racks, stop logs and the necessary lifting mechanisms.

The pumped-storage hydroelectric power station is equipped with four sets of reversing Francis turbines for a 90 m head. Synchronous generators with 13.8 kV voltage and two-way rotation are used in both the turbine and storage pumping operation. The generator voltage is transformed to 420 kV outgoing voltage by unit transformers.