Method of modal analysis for wind turbines based on air-structure coupling vibration model

In order to explore the modal characteristics of the wind turbine, aiming at 1500 kw variable speed variable pitch double-fed wind turbines which are the mature products in market, established the whole wind turbine dynamic modal equations by Lagrange method and obtained modal parameters through decoupling calculation. Then process on-site testing to obtain measured modal characteristic parameters. The results of both analytical dates show that deviation between theoretical data and measured data is less than 10%. The results show a good consistency, the theoretical model and the subsystem boundary conditions simplified methods are consistent with the actual situation, indicating a high reliability. The theoretical model verifies that natural frequencies of the major structural components for testing wind turbine within the operation speed range can avoid coupled resonance phenomenon which meets GL specification requirements. It is can effectively conduct the wind turbine development, design and optimization.