An improved real-time economic NMPC scheme for Wind Turbine control using spline-interpolated aerodynamic coefficients

Nonlinear Model Predictive Control (NMPC) is a strong candidate for the control of large Multi-Mega Watt Wind Turbine Generators (WTG), especially when reliable Light Detection And Ranging (LIDAR) systems are available. Recently, a real-time NMPC for WTG control has been proposed, but had a limited reliability if deployed over the full WTG operating range due to the difficulty of handling the WTG aerodynamic coefficients over a large domain and of using a Gauss-Newton Hessian. In this paper, we address these two issues. A fast surface B-spline code has been developed specifically to tackle the interpolation of the aerodynamic coefficients for NMPC-based WTG control. A novel Hessian approximation for the NMPC problem is used, for which an efficient and inexpensive regularization is proposed. The approach presented is real-time feasible, and accurate over the full operating range of the WTG.