Stress-informed Control of Medium- and High-head Hydropower Plants to Reduce Penstock Fatigue

TL;DR

This paper introduces a model predictive control approach that models hydraulic transients to reduce penstock fatigue in hydropower plants, enhancing long-term durability while maintaining real-time operational capabilities.

Contribution

It presents a convex MPC scheme that explicitly models hydraulic transients to effectively reduce penstock fatigue in hydropower plants, a novel approach for long-term infrastructure health.

Findings

Significantly reduces penstock fatigue in simulations

Outperforms existing control approaches

Achieves real-time feasible optimization

Abstract

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.