Design Tradeoffs of Wind Turbine Preview Control

Recent work demonstrated the benefits of preview wind measurements for turbine control. This paper investigates the basic design tradeoffs between turbine performance, preview time, and pitch actuator rate limits. A Region 3 rotor-speed tracking problem is formulated in continuous-time as an optimal control problem using a simple one-state rigid body turbine model. The exact analytical solution to this problem provides insight into the fundamental performance limits. These analytical results are compared with the performance of an H_∞ preview controller simulated on a higher fidelity, nonlinear turbine model with realistic wind sensor models. The performance versus preview time characteristics of the H_∞ controllers are in agreement with the predictions from the lower fidelity model. Thus, the analytical results obtained with the low-order model can provide design guidelines for the use of preview information in turbine control.