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.<\/p>\n\n\n\n
The doctoral thesis of Daniel Biner<\/strong>, carried out as part of the European project XFLEX HYDRO<\/strong>, examined the impact of these new ways of working on the fatigue of a variable-speed reversible pump-turbine<\/strong>. The work focused on a 5 MW industrial demonstrator fitted with a full-power frequency converter, enabling extensive control of the rotational speed.<\/p>\n\n\n\n The research combined hydraulic and mechanical simulations, fatigue analyses and experimental testing on prototypes<\/strong>. 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.<\/p>\n\n\n\n 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<\/strong>, 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.<\/p>\n\n\n\n