Optimizing Wind Turbine Load Reduction: Trade-offs Including Blade Angle Deviation in PID Individual Pitch Control and MPC Collective Pitch Control

Abstract

This study investigates trade-offs in Individual Pitch Control (IPC) for wind turbines by optimizing proportional-integral-derivative (PID) controllers, introducing blade pitch angle deviation as a performance objective that has received little attention so far. Smaller deviation angles reduce IPC-induced actuator duty cycles and lower the risk of unintended increases in out-of-plane root moments caused by load sensor inaccuracies. Another drawback of larger blade deviations is that, during emergency shutdowns, blades can stop at different pitch angles, potentially causing temporary asymmetric aerodynamic braking forces and higher transient loads than collective pitch control. While often disregarded in proof-of-concept studies, keeping blade deviation within acceptable limits is crucial for implementing IPC in production. By quantifying blade deviations alongside damage equivalent loads (DEL), power output, and actuator energy, this study provides a comprehensive IPC assessment. Results reveal a trade-off between DEL reduction and blade deviation in IPC-PID controllers. Additionally, a comparison with Model Predictive Control (MPC)-based Collective Pitch Control (CPC) highlights that incorporating wind information and advanced algorithms can improve this trade-off by shifting the Pareto front.