The Research On Individual Blade Pitch Control Of Wind Turbine For Blade Load Reduction

This paper presents an optimal individual pitch control method of decreasing the unbalanced load caused by wind shear, thus prolonging life of wind turbine. A mathematical model and simulation platform of the pitch control system were built and on the basis of aerodynamics, a mathematical model of the load optimization was established. The angles of three blades used as reference values of the controller are calculated by the load optimization mathematical model, the objective function of which is unbalanced load minimization based on blade element theory and power is the essential restriction as well as the range of pitch angles.The paper introduces the mathematical models of wind power conversion system, such as wind turbines, generators, transmission mechanism and pitch controller system, then based on them builds the digital simulation platform of wind power conversion system under the environment of SIMULINK in order to simulate and calculate. Secondly, the wind according to rule in nature was recommended, especially wind shear effect which is used to describe the relationship of wind and height. By learning the aerodynamics we applied blade element-momentum theory in the calculation of fan load and put a blade divided into many range to analyze of the force and calculate the force of the blade by integralling the range to the blade. Based on the characteristics of load formula got by the above theory, this article designed the mathematical model of the load optimization in order to calculate the optimal angles. By writing programs in MATLAB, we can calculate the load of blade and the power to simulate, compare and analyze the model in different cases.Thirdly, this article analyzed the pitch control methods, which was applied in the case of high wind and a mathematical model of the load optimization was added to get the angles by calculating the model. The angles were set as the reference to control the pitch individually. Above is the key point, which is individual blade pitch control of wind turbine for blade load reduction.In the end, the paper conducted the pitch control, individual blade pitch control base on weight and individual blade pitch control of wind turbine for blade load reduction. The performance of the proposed individual controller is evaluated on the UPWIND 500kW wind turbine model and compared with typical individual pitch control. Simulation results indicate that the controller lessens the unbalanced load significantly, without the loss of power and the frequent pitching.