Daniel Biner’s PhD
The growing integration of intermittent renewable energy sources is increasing the need for flexibility and stabilisation within the electricity grid. Pumped-storage power stations play a vital role in this context, thanks to their ability to rapidly generate, absorb and store large quantities of energy. Variable-speed technologies make it possible to further increase this flexibility, but the new operating modes they enable require an assessment of their impact on the service life of hydromechanical components.
The doctoral thesis of Daniel Biner, carried out as part of the European project XFLEX HYDRO, examined the impact of these new ways of working on the fatigue of a variable-speed reversible pump-turbine. The work focused on a 5 MW industrial demonstrator fitted with a full-power frequency converter, enabling extensive control of the rotational speed.
The research combined hydraulic and mechanical simulations, fatigue analyses and experimental testing on prototypes. Numerical methodologies combining CFD and structural analysis have been developed to evaluate the stresses and damage to the impeller over a wide operating range, particularly under partial load and during transient phases. Specialised instrumentation fitted to the prototype enabled these numerical approaches to be compared with measurements taken directly on the machine.
In particular, the research has made it possible to investigate how controlling the rotational speed can be used to optimise operating trajectories and start-up sequences, whilst limiting the fatigue stresses on the wheel and the penstock. They thus help to demonstrate that increasing the flexibility of pumped-storage power stations can be reconciled with managing the service life of the equipment, paving the way for more flexible and sustainable operation of hydroelectric facilities.
Publications and related work
Doctoral thesis
D. Biner, Fatigue investigations of a converter-fed variable-speed pump-turbine for flexible power generation, PhD thesis, EPFL, 2024, Thesis No. 10711.https://doi.org/10.5075/epfl-thesis-10711
Newspaper articles
Biner, D., Hasmatuchi, V., Dujic, D., & Münch-Alligné, C. (2026). Fatigue design of Francis-type pump-turbine runners under flexible power generation. Results in Engineering, 29, 109480. https://doi.org/10.1016/j.rineng.2026.109480
Conference papers / proceedings
Biner, D., Hasmatuchi, V., Lecointre, C. L., Quarroz, A., Nicolet, C., Alligné, S., … & Münch-Alligné, C. (November 2024). Experimental investigation of a FSFC variable-speed pump-turbine prototype – Part 2: runner fatigue reduction. In IOP Conference Series: Earth and Environmental Science (Vol. 1411, No. 1, p. 012031). IOP Publishing.
Biner, D., Dujic, D., & Münch-Alligné, C. (March 2025). Numerical study of pressure fluctuations in a variable-speed pump-turbine with head variations. In IOP Conference Series: Earth and Environmental Science (Vol. 1483, No. 1, p. 012028). IOP Publishing.
D. Biner, S. Alligné, V. Hasmatuchi, et al., “Numerical fatigue damage analysis of a variable
”speed of the Francis pump-turbine during start-up in generating mode”, IOP Conference Series: Earth and
Environmental Science 774 (2021) 012070, 2022
D. Biner, P. Bontepms, D. Dujic, et al., “Discretisation uncertainties in flow and fatigue damage”
”Simulations of a reversible Francis pump-turbine operating off-design in turbine mode’, in
Advances in Hydroinformatics, 2022, pp. 649–670
J. Schmid, S. Alligné, D. Biner, et al., “Optimisation of the turbine start-up sequence for a full-scale
”Variable-speed pump-turbine frequency converter’, IOP Conference Series: Earth and Environmental
Science, vol. 1079, no. 1, pp. 012–109, September 2022
S. Alligné, A. Béguin, D. Biner, et al., “Turbine mode start-up simulation of a FSFC variable-speed
”Pump-turbine prototype – Part I: 1D simulation’, IOP Conf. Series: Earth and Environmental
Science 774 (2021) 012052, 2021
D. Biner, S. Alligné, V. Hasmatuchi, et al., “Turbine mode start-up simulation of a variable-speed
”Francis Pump-Turbine Prototype – Part II: 3-D Unsteady CFD and FEM”, IOP Conference Series: Earth and
Environmental Science 774 (2021) 012070, 2021
Popular science article
Biner D, Pacot O, Decaix J, Münch-Alligné C (2022), «Greater flexibility thanks to simulations », ElectroSuisse Bulletin 2, 2022
Other publications not directly related to the scope of the thesis:
P. Bontemps, D. Biner, C. Münch-Alligné, et al., “Online loss calculation and optimisation of
”An m3c-driven externally excited sm’, IEEE Transactions on Industrial Electronics, vol. 71, no. 6,
pp. 5608–5617, 2024
J. Decaix, D. Biner, J.-L. Drommi, et al., “CFD simulations of a Y-junction for the implementation of
”hydraulic short-circuit operating mode’, IOP Conference Series: Earth and Environmental Science,
Vol. 774, No. 1, pp. 012–013, June 2021
