  The displacement of conventional generation in favor of stochastic renewable
requires increasing regulation duties from the remaining dispatchable
resources. In high- and medium-head hydropower plants (HPPs), providing
regulation services to the grid and frequently changing the plant's set-point
causes water hammer, which engenders pressure and stress transients within the
pressurized conduits, especially the penstock, damaging it in the long run.
This paper proposes a model predictive control (MPC) that explicitly models the
hydraulic transients within the penstock. It achieves to reduce the mechanical
loads on the penstock wall, and, consequently, fatigue effectively. Thanks to a
suitable linearization of the plant model, the optimization problem underlying
the MPC scheme is convex and can be solved with off-the-shelf optimization
libraries. The performance of the proposed controller is tested with numerical
simulations on a 230MW medium-head HPP with Francis turbine providing primary
frequency control. Simulation results show substantially reduced penstock
fatigue, existing approaches outperformed, and problem resolution times
compatible with real-time control requirements.
