Project, pictures and data of dam of ITAIPU
|Principle of energy conversion at
hydro power plants:
The potential energy given by the water stored in the lake at a certain height above the outlet. This energy is converted into cinetic energy by letting it flow down the tubes. This cinetic energy is given to the blades of the water tubine which transform it into a mechanical rotation. This rotation is used to drive the electric generatores. The electicity is generated by moving magnetic fields along conducting coils.
At ITAIPU the total potential energy of the usuable part of the lake is given by:
Wpot = 0.5 (hul +hip) (hul -hip)* g * A * r
The upper result is related to sea level, while the head of the penstock is 118.4 m only, the used potential energy is:
Wpot = 5,49 * 1016 J = 54,9 PJ
The water intake of one single 715 MW Francis-turbine is 700 m³/s, its weighted efficiency is 93.8 %. So with the lake filled up the turbines can produce 13 400 GWh until the penstock inlet is out of water (if no water follows), which means 44 days full power operation of the plant.
The generators have an efficiency of 98.6 %, while the 50 Hz types with 66 poles have a rated output of 823.6 MVA at (90.9 rounds per minute) and a power factor of 0.85, the 60 Hz types with 78 poles have a rated output of 737 MVA (at 92.3 rounds per minute) and a power factor of 0,95. The output voltages are both 18 kV.
Each year ITAPU generates 75-77 TWh of electricity and avoids 67.5 million tons of carbondioxide emissions.