Individual blade-pitch system for tidal current turbines with fuzzy logic control based on load reproduction

With the increasing scale of the tidal current turbine, the asymmetric load problem caused by shear flow and turbulence has become prominent, resulting in vibration and fatigue losses. To address the challenge of measuring the asymmetric load on a rotating impeller underwater precisely, a load reproduction method is introduced to calculate the asymmetric load. To address the demand for better power control and load management in tidal current turbines, an individual pitch system is recommended and proven effective in reducing the asymmetric load. In this study, an individual pitch system using hydraulic swing cylinders is proposed, which features a simple structure and a compact size relative to the traditional individual pitch system. A fuzzy-PID individual pitch control strategy based on the load reproduction method is utilized to control the time-varying tidal current turbine pitch system. The simulation results demonstrate that the individual pitch system with fuzzy-PID control can reduce the fluctuation and the RMS value of the tilt moment more effectively than the PID individual pitch control. The semi-physical experiment is conducted. The experimental results validate the simulation results and demonstrate the effectiveness of the proposed individual pitch system and fuzzy-PID individual pitch control strategy in power and load control.