Study on the dynamic modeling and natural characteristics of wind turbine drivetrain considering electromagnetic stiffness

Abstract

As the wind turbine starts running, the drivetrain would suffer a significant impact load, which severely endangers the safety of the wind turbine. Therefore, ensuring the capacity of the drivetrain to resist the impact load is critical to prevent wind turbine downtime. Most of the drivetrain models fail to balance the efficiency and accuracy, and lack the concern on the responses of the drivetrain at start-up. In this paper, a rigid-flexible coupling dynamic modeling method and an experiment method are proposed to study the modal characteristics of the doubly-fed wind turbine drivetrain at start-up. The drivetrain model is constructed applying the electromagnetic (EM) stiffness and the mesh deformation of the multistage gear transmission as well as the flexibility of bearings, main shaft and parallel stage shafts. The proposed model is validated by the professional software. A new measuring point is discovered to record the experimental data influenced by the electromagnetic stiffness. An efficient method is further developed to calculate the electromagnetic stiffness. The modal shape, modal energy and amplitude-frequency responses of the drivetrain are investigated considering the electromagnetic stiffness. The proposed method can be used to guide the drivetrain optimization and the experiment.