Optimal control of variable speed hydropower. Utilising model predictive and virtual inertia for delivering power system services.  2021 Tor Inge Reigstad, PhD.

As the share of wind and solar energy production increases, more flexible production and loads are required to control the balance of the grid.  

In his Thesis, Tor Inge Reigstad proposes a new control method for optimal control of hydropower plants with variable speed. His work shows that the variable speed generators can provide siginificant stabilitation services to the network.

Trailing edge vortex shedding in hydraulic turbines and the effect of stream-wise vorticity on vortex induced vibrations, 2021. Kristian Sagmo, PhD.

Experiments as well as some numerical simulations were conducted investigating the resonance region of vortex induced vibrations for different trailing edges of a hydrofoil in channel flow.

The study focuses on the usefulness of stream-wise vorticity for the mitigation of vortex induced vibrations for the different trailing edge geometries.

Assessment on the swelling and disintegration potential of weak and weathered rocks in water tunnels of hydropower projects - a contribution based on use of laboratory testing methods, 2020. Lena Selen PhD.

The extensive laboratory work in combination with the wide-ranged cooperation has resulted in suggestions on project-specific modifications on standardized laboratory tests which enable an interpretation of weak rock behavior closer to the in-situ situation of water tunnels. Improvements are made explicit on the oedometer swelling test procedure in operation at the NTNU laboratory, including preparation techniques and apparatus configuration, and investments on new equipment is in progress. Additionally, the research includes an experimental application of the in-situ flatjack test normally used to measure in-situ stresses around tunnels which now is installed in a hydropower tunnel to measure changes in stress during the initial phase of operation. 

Hydraulic and structural evaluation of rockfill dam behavior when exposed to throughflow and overtopping scenarios. 2020. Ganesh Hiriyanna Rao Ravindra, PhD.

Ravindra has published several scientific articles during his PhD-research. He has investigated flow and overtopping of rock fill dams and, among other things, found that the dam toe can be crucial in extreme load situations such as overtopping. The data from the doctoral thesis will now be used to develop improve the design of the dam toe of rock fill dams. Read more about his research.

Francis turbines for variable speed operation. 2020. Igor Iliev, PhD. 

Iliev designed 421 hydropower turbines during his PhD-research and chose the best for variable speed operation. Read more about his reseach.