Offshore wind turbines real-time control using convex nonlinear economic MPC scheme

With the rapid advancement of wind power technology, the importance of lower operating costs and improved real-time control capabilities for offshore wind turbines (OWT) has increased. Nonlinear Economic Model Predictive Control (NEMPC) has gained attention due to its effective balancing of economic objectives. However, implementing real-time control for OWTs faces challenges due to their strong nonlinearity. This study proposes a convex NEMPC (CNEMPC) by incorporating variable transformation to account for the instantaneous energy stored in OWTs. The CNEMPC includes a set of convex constraints and aims to maximize power generation while minimizing fatigue loads on system components like the tower and gearbox. A newly designed moving horizon estimator provides an initial state estimation for the CNEMPC. Real-time iteration of the CNEMPC is achieved by leveraging the similarity of nonlinear programs between adjacent sampling moments. The effectiveness of the proposed control strategy is verified using a 5 MW OWT as the simulation target.