Wind Turbine Structural Load Reduction by Linear Single Model Predictive Control

A new model-based predictive controller (MPC), specially oriented to facilitate its practical implementation, is presented. This controller is devoted to reduce the structural load in the drive train or/and the rotor of a wind turbine. It keeps its complexity and computational load low, by using a single linear internal model throughout the full range of use. To validate the new approach, the performance of two versions of such a controller is compared to the baseline case. Specifically, the implemented controllers are focused on mitigating the torsional vibrations that appear in the drive-train during turbine operation for wind speeds above rated. First, numerical simulations are used to study the potential performance. Then, the proposed methodology is put into practice by using rapid prototypes of the real-time controllers applied to a specifically designed Hardware-in-the-Loop (HiL) simulator of wind turbines. This HiL simulator realistically reproduces the performance of the National Renewable Energy Laboratory (NREL) 5 MW wind turbine. In order to confirm the practical applicability of such MPC algorithms, the electronic platform mounted on the rapid-prototyping system has a similar -or inferior- computational power than the industrial control platforms used in the actual wind turbines. Anyway, the computational burden is analyzed in detail.