Hydro power plant Slapy (CZ)
In this article we invite you to discover hydro power plant Slapy in Czech Republic – the first large construction of Vltava cascade after world war II. Slapy is situated in Central Bohemia, approx. 25 km south of the capital Prague.
Type of hydro power plant
Slapy can be classified as medium pressure, accumulation, peak type hydro power plant.
Scheme of hydro power plant Slapy
An illustrative scheme of hydro power plant Slapy is depicted in figure 2.
Description:
1 … Machine room
2 … Cranes
3 … Kaplan turbine
4 … Generator
5 … Upper reservoir
6 … Feeder
7 … Dam
8 … Substation
9 … Segment closing valve
10 … Fast closing valve
History
Medium pressure hydroelectric power plant Slapy was commissioned in 1955. It was the first large hydro power plant of Vltava cascade after WWII. First turbine was commissioned on October 6, 1955. There are in total three Kaplan turbines designed for nominal head of 56 meters. Each machine set has a rated power of 48 MW. Since the begining of operation the power plant generated almost 20 million MWh of electric power (equivalent of consumption of Prague for about 3.5 years).
Water works Slapy was built between 1949 and 1955. The hydro power plant is located directly on the body of the dam. It consists of the machine room, step-up transformers, auxiliary equipment, internal 110 kV substation, 22 kV substation and an administrative building. From the substation the electric power is brought out via 110 kV power cables.
Curiosities
- In 1954, still before commissioning, the plant captured water from flood and protected Prague against flooding. At the same time, the flood accelerated the first filling of Slapy waterworks.
- Hydro power plant Slapy successfully resisted severe floods on Vltava river in August 2002 and remained operational with full power throughout the entire critical period.
- The power plant needs approx. 8 m³ of water to generate 1 kWh of electricity.
- Power generated by Slapy since its commissioning exceeded 19 million MWh and would cover the entire consumption of Czech Republic for approx. 4 months.
- After completing the modernization of TG2 in 2022 the yearly generation output shall increase by approx. 10’000 MWh.
- The turbine impeller with 3.7 m of diameter swallows 100 m³ per second.
Power control / grid balancing
Fully automated power plant generates peak electric power and helps to balance the national power grid. The start-up time requires less than 2.5 minutes. Power control of Slapy is regulated remotely from centralized dispatch center in Štěchovice. Fluctuation of water outlet is compensated by water reservoirs in Štěchovice and Vrané. In emergency case the power plant can be controlled locally.
Water basin has a volume of 269.3 million m³ with concrete gravitational dam of 65 m height. The dam is situated in a narrow gorge and features unique construction solution. There are well visible four overflow fields with closures 15 x 8 meters used in the event of floods (rated capacity of 3’000 m³/s). Created dam lake has a surface of 14 km² and length of 44 km. Large accumulation capacity has not only power generation purpose. It also enables water flow control in Vltava river and provides basic flood protection. Finally, the lake became a popular summer recreation area, especially for citizens of Prague.
Basic technical data of hydro power plant Slapy
Installed power: 144 MW (3 x 48 MW)
Rated speed: 230.8 rpm
Runner diameter: 3’700 mm
Turbine type: Kaplan
Generator voltage: 10.5 kV
Start-up time: 136 s
Weight of generator rotor: 240 t
Weight of turbine block: 60 t
Weight of turbine impeller: 35 t
Length of steel feeders to the turbines: 50 m
Water height: 27 to 56 m
Yearly power generation: ~ 300’000 MWh (~300 GWh, long term average)
Number of starts per day: 1.8 (long term average)
Running hours per day: 8.3 (long term average)
Modernization
Turbine-generators TG3 and TG1 have already been modernized in 2011 and 2020, respectively. Modernization of TG2 is currently in process and will be finalized in 2022. Afterwards, the hydro power plant Slapy will be in similar condition like 65 years ago when it was commissioned.
References
[1] The Slapy hydroelectric power station, https://www.cez.cz/en/energy-generation/hydroelectric-power-plants/cez-hydroelectric-power-plants/czech-republic/slapy
[2] Hydro applications (series), https://mb-drive-services.com/category/hydro-applications/
