Lifetime and operating impairments

Photo: Juliet Landrø/ HydroCen

To run production as profitably as possible without compromising the condition of the components in the hydropower plant, it is important to have the right information about how the components are affected by different operating patterns.

Most hydropower plants in Norway are designed to run with relatively constant production, where components slowly and surely wear out and age over time. This could mean, for example, that the insulation of the generator windings deteriorates over time or the development of cracks in the impeller of the turbine.

To avoid major damage, costly repairs and downtime, the wear must be detected and repaired in time. This can be done, for example, by condition monitoring and fault detection of tunnels, turbines, and generators, among other things. When production is also increasingly controlled by varying market prices, with increased use of peaking power (start/stop) and variable production, the components of the hydropower plant face increased wear/degradation and there is an increasing risk of breakdown.

More variation means increased wear

Rapid variations in pressure because of rapid changes in production could cause the rock masses in the water tunnel to collapse, and rapid variations in temperature could destroy the insulation in the generator over time.

In HydroCen, new methods are being researched and new tools developed to make it easier and more efficient to measure the condition of various components in the hydropower plant, and to include this in the planning of maintenance and production.

Some examples of results from the centre have been:

• A cheaper and more efficient test to measure the bearing capacity of the rock masses in hydropower tunnels. The test allows you to measure the rock mass's minimum stress in larger parts of the tunnel and can thus obtain more precise measurements of how much the rock can withstand.
• A method for more variable production patterns without risking the rock masses in the tunnel being exhausted and collapsing.
• Improvement of the method for testing the properties of the rock masses, with a focus on swelling rocks and weathered rock.
• Models that include the cost of different operating patterns and the costs of starting/stopping during peaking power.
• New knowledge about how the stator winding in the generator is affected by temperature variations from frequent start/stop during peaking power.
• A new method for detecting faults in the generator by measuring the magnetic field around the generator.

The topic is strongly linked to the research the centre has carried out on Data collection, measuring equipment and analysis, where several tools have been developed that make it easier and more efficient to carry out condition analysis of the various components, so that errors can be detected before they go wrong, and thereby reducing costs and downtime for the power plant.