20 / 52
20
Background
The variations in the grid frequency in the Nordic countries have increased during the last
years. The turbines are also more often operated at part load or maximum load. In this
project these effects will be studied, to see if they can explain why some relative new Francis
turbines have experienced problems with cracks.
The generator’s torque and the runner’s torque
are acting in opposite direction, and this leads to
stresses in the material of the runner.
These stresses will be studied with Fluid
Structure Interaction (FSI) where the effects from
both the fluid side and the structural side of the
turbine are simulated.
Different things need to be considered:
• The speed droop of the turbine
• The variations in grid frequency
• Design of the conduit system
• The governor
• Design of the runner
• The operation plan for the unit
PhD Thesis
Waterpower Laboratory
Dynamic Loads in Hydro
Power Plants
By Rakel Ellingsen
Supervisor: Pål-Tore Storli