Hydraulic turbines are subject to an increasing number of start/stop and load variations mainly due to the introduction of wind power and the deregulation of the electricity market. Therefore, the stresses casued by these events should be given more attention as they cause heavy cyclic stresses and high cycle fatigue on the turbines.
One start-stop may reduce the service period of a runner by about 15 hours as well as putting additional cost of break-down to the power plant owner. There is a need to better understand such operation conditions to minimize failure and decrease wear of the machines but also predict upcoming trends for design purpose. The development of accurate and cost-effective measuring techniques is an essential element in this context as well as the implementation and analysis of full-scale measurements.
Several measurements are performed during transient and steady operations on the runner and shaft. This data will now be evaluated and analysis carried out on the coupling between runner and shaft. If successful, the analysis may allow determination of expected runner life, exclusively from measurements on the shaft. Such measurements may thereby allow operation optimization of the turbine, reducing cost of operation and maintenance.
Today, measurements on the runner are necessary to assess its life. Such measurements are expensive and difficult to perform. This project is expected to give guidelines on the implementation of measuring techniques that allows for simpler measurements to assess the expected life of a runner.
The following measurements performed on the Porjus U9 prototype will be further analysed:
- Stresses on the blade.
- Pressure on the blade.
- Acceleration of the runner in 3 axes.
- Torsion, bending and axial load on the shaft