30 September 2025
Smarter turbine control can extend hydropower lifespan
Hydropower turbines are increasingly used to balance the fluctuations of wind and solar power. New research shows that adjusting guide vanes in a novel way can reduce damaging pressure pulsations, paving the way for longer-lasting and more reliable turbines in the renewable energy system.
As more renewable energy sources like wind and solar feed into the grid, hydropower has taken on a new role. Turbines are no longer just producing electricity at steady load but are constantly adapting to help stabilize the system. This often means running at very low loads or even at speed-no-load, when the turbine rotates without generating power. Such conditions create chaotic water flows that trigger harmful pressure pulsations inside the turbine, shortening its lifespan and increasing the risk of material fatigue.
"My research focuses on how water behaves inside the turbine during these demanding conditions. Understanding the flow is key to making turbines more reliable when they are used for grid regulation.", says Jelle Kranenbarg, doctoral student in Fluid Mechanics at Luleå University of Technology.
Asynchronous guide vanes reduce pulsations
In his thesis, Kranenbarg has tested a mitigation strategy that uses asynchronous guide vanes. Instead of opening all the guide vanes evenly, as is normally done, some are opened more while others remain closed. This creates a controlled jet of water that reduces the swirling vortices responsible for strong pressure pulsations.
The results show that the method can significantly lower pulsations and make the flow more predictable, especially during speed-no-load operation.
"With asynchronous guide vanes we can limit the harmful pulsations without adding any extra equipment, just by controlling the vanes differently," says Jelle Kranenbarg. "That makes the solution both practical and cost-effective."
Jelle Kranenbarg, doctoral student in fluid mechanics at Luleå University of Technology.
Balancing efficiency and lifespan
The technique is most effective at speed-no-load, when vortices are formed upstream of the runner. During part-load operation, when vortices originate downstream of the runner in the draft tube, the effect is weaker. While pressure pulsations are reduced, new challenges arise such as efficiency losses and asymmetric forces on the turbine.
Even so, the overall effect is positive for turbine health. By reducing the pressure variations, the method can extend the lifespan of hydropower turbines and make them more reliable as balancing tools in a renewable energy system.
"Hydropower is crucial for stabilizing the grid when wind and solar production fluctuates," says Jelle Kranenbarg. "If we can operate turbines more safely and extend their life, we strengthen the whole renewable energy system."
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