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Litostroj - Reversible Pump Turbines
Design principle and range of use: Pump-turbines are used in pumped-storage hydropower plants (PSP). Their role in the electrical grid system is to store non used energy by transforming it to the potential energy of water. Pump-turbines can work either as a pump to store water in an upper reservoir or as a turbine to use the water to generate power. An additional role of pump-turbines and PSP systems in recent years has been balancing and stabilization of the electrical grid. Litostroj Power provides state-of-the-art solutions tailored to customers’ demands in the most various environments. In order to achieve high efficiency and a wide operating range in both the pump and turbine regimes all machines are hydraulically optimized and model tested in Litostroj Power’s hydraulic laboratory.
Pumped storage hydropower plants equipped with reversible units consist of two reservoirs (upper and lower) connected by a penstock. The reversible unit – located at the end of the penstock - is usually isolated by a main inlet valve, which is coupled to a welded steel spiral case where the guide vanes serve to control the unit discharge and power output.
The runner-impeller is hydraulically and mechanically designed to work in both pumping and power generating mode. Transition from pump to turbine regime can be very quick and repeated several times per day.
By means of the shaft, the runner-impeller is coupled to the generator-motor, which transforms the mechanical work into electrical energy or vice-versa.
Double-regulated Deriaz pump-turbine allows adjusting the runner blade angle similarly as in Kaplan runner and thus enables efficient use of water in turbine regime under a wide range of head and discharge conditions, on one hand, and adjustment of the power consumption during pump regime, on the other. Such ability to control the power consumption in pumping regime omits the need for variable speed generator. This solution is typically used at a lower head (up to 50 m).
- Francis pump-turbine
- Deriaz-type pump-turbine
- Energy accumulation
- Heads from 10 m up to 750 m
- Wide range of heads and discharges
- Outputs up to 350 MW
- Short starts and transitions (1-3 min)
- Runner diameters up to 7 m
- Grid frequency regulation
- Special design for non-restricted pumping power range available
- Generating power range from 2 - 100%