A Research On Modeling And Simulation Technology Of Wind Turbines

Modeling and simulation have been an important method for the study on the basic principle, the control technology, and the coordinated optimization for wind turbines. At present, the influence of uneven wind speed and unbalanced blades on the wind turbine characteristics and the grid connected power quality is more and more serious, so this paper analyzes the influence of uneven wind speed and unbalanced blades on the wind turbines and puts forward an improved grid connected control strategy to mitigate the fluctuation of the grid connected power based on the wind turbine model by simulation.First of all, the wind turbines models are built. The wind turbine aerodynamic part, driving chain, generator, converter and control system are modeled based on the structure and operating principle of wind turbines. The wind turbine aerodynamic model based on the BEM (Blade Element Momentum theory), the equivalent power model of converter and the power-voltage model of DC link are modeled especially according to the study purpose of this paper.Secondly, the aerodynamic characteristics are analyzed. Considering wind shear, tower shadow effect and the unbalanced blades, the aerodynamic loads model of large scale wind turbine are built based on the BEM; by analyzing the simulation results of aerodynamic loads in time domain and frequency domain, the influence of wind shear, tower shadow effect and unbalanced blades on the aerodynamic loads characteristics and the resonance characteristic of relative mechanical components are obtained.Finally, the stable control strategy of grid connected power is studied. The influence of wind shear, tower shadow effect, and unbalances blades on grid connected power are analyzed based on the model built before, and the classical grid connected control strategy is improved to mitigate the influence of the three elements; the classical grid connected control strategy and the improved one are both simulated on the model platform, and the simulation results verify the validity of the improved control strategy.