Modeling and Control to Mitigate Resonant Load in Variable-Speed Wind Turbine Drivetrain

Failure of the drivetrain components is currently listed among the most problematic failures during the operational lifetime of a wind turbine. Guaranteeing robust and reliable drivetrain designs is important to minimize the wind turbine downtime as well as to meet demand in both power quantity and quality. While aeroelastic codes are often used in the design of wind turbine controllers, the drivetrain model in such codes is limited to a few (mostly two) degrees of freedom, resulting in a restricted detail in describing its dynamic behavior and assessing the effectiveness of controllers on attenuating the drivetrain load. In the previous work, the capability of the well-known FAST aeroelastic tool for wind turbine has been enhanced through integration of a dynamic model of a drivetrain. The drivetrain model, built using the Simscape in the MATLAB/Simulink environment, is applied in this paper. The model is used to develop a power-electronics-based controller to prevent excessive drivetrain load. The controller temporarily shifts the closed-loop eigenfrequency of the drivetrain through the addition of virtual inertia, thus avoiding the resonance. Simulation results demonstrating the fidelity of the expanded drivetrain model as well as the effectiveness of the virtual inertia controller are presented.