Enhancing Operational Stability of Floating Offshore Wind Turbines Based on ‘Plan-Control’ Strategy

Floating offshore wind turbines (FOWTs) are significantly influenced by the coupled wind-wave operating environment, where the motion of the floating platform reduces the system's operational stability. Existing advanced control strategies alter the structure of industry-standard controllers, posing a risk of operational failure. To address this issue, this paper proposes a ‘Plan-Control’ strategy for FOWTs. The inner ‘Control’ loop adopts an industry-standard controller, while the outer ‘Plan’ loop integrates a planner based on nonlinear model predictive control (NMPC). For the inner loop, the controller provides reference signals for generator torque and blade pitch angle to the actuators, with the core control parameters specified by the planner. For the outer loop, the planner determines the core control parameters by solving a multi-objective cost function. The multi-objective cost function includes suppressing platform motion and minimizing speed/power fluctuations. Finally, simulation experiments under realistic wind-wave environmental conditions are conducted to validate the comprehensive improvement in the operational stability of FOWTs.