Research On Sturctures Damage Diagnosis Method Of Large Wind Turbine Blade

With the exploitation and utilization of renewable energy, wind energy has become one of the primary energy of the world because of its abundant reserves, extensive distribution and little impact on the environment, and wind power technology is also increasingly developed.As the key components of the wind turbine, wind turbine blades is easy to damage in the harsh natural environment, and due to the influence of various factors, the damage of blade can’t be identified timely and effectively. Blade damage will cause serious economic losses on wind farm, and it also has a very important influence on the safe operation of wind turbines.So the research on damage identification method of wind turbine blade under common damage types is very important. Based on the analysis of common damage identification method, the application of vibration testing technology and computational intelligence technology to structure damage identification of wind turbine blade is paid more attention in the thesis.Firstly, the basic structure of the blade, common damage types and the common damage identification method of blade are introduced, which provide the theoretical basis to establish the finite element model of the blade, and to choose the damage identification methods.Secondly, based on the operation characteristics of blade in the real environment, the blade is treated as a cantilever beam which has the same structure as blade. Then take a 2MW wind turbine blade as research object, which finite element model is built based on ANSYS,so the blade modal parameters can be calculated before and after damage, and damage identification method based on vibration characteristic is adopted to identify the damage position of the blade.Then, the damage identification problem of blade can be converted to a mathematical problems, which is about objective function optimization. The common genetic algorithm and fruit flies algorithm is adopted respectively to identify the damage of the wind turbine blade,and the fruit flies algorithm is improved for its lack on identification accuracy. Through the numerical simulation results of single damage and multiple damage of blade, we can find that the improved method has an obvious improvement of the recognition precision under different damage condition.Finally, a laboratory bench for vibration testing system of blade is set up. Through the method of manufacturing crack to simulate the crack damage of blade, the modal analysis technology is adopted to calculate the modal parameters before and after the damage of blade,then the method above can be used to identify the damage of the blade, which can prove the effectiveness of the method for the identification of blade damage.