Fuzzy PID Individual Pitch Control with Effective Wind Speed Estimation for Offshore Floating Wind Turbines

Individual Pitch Control (IPC) is a crucial mechanism for mitigating asymmetric loads in offshore floating wind turbines (OFWTs). Conventional IPC systems face significant limitations in wind speed estimation accuracy and control strategy robustness, leading to load fluctuations and power degradation. To address these challenges, this study proposes a novel IPC system incorporating an innovative effective wind speed estimation method and a fuzzy PID control strategy. The wind speed estimation is achieved using polynomial fitting of the tip speed ratio and pitch angle. The fuzzy PID control strategy for IPC employs variable control gains calculated based on wind speed, azimuth angle, and blade root loads. To verify the performance of the proposed control system, it is compared against the baseline control system implemented in the OpenFAST software v1.0.0 by a case study of the NREL 5MW OFWT. Results demonstrate that the proposed system has high accuracy in wind speed estimation and maintains rated power output while reducing blade flapwise and pitching moments. Notably, the proposed EWSE has a 53.1% improvement in median error and a 19.23% improvement in data error threshold compared with a reference EWSE. Under strong turbulent conditions (15% turbulence intensity), the proposed system achieves a reduction of 17.9% in flapwise moment and 12.9% in pitching moment compared with a baseline controller.