Wind Power Pitch Control Based On Fractal Interpolation

Although wind power generation has the advantages of pollution-free,recyclable and low maintenance cost,the fluctuation of wind is random.Thus when the output power of wind power generator is too high,it is necessary to stabilize the output power by pitch control.At present,with the increase of wind power unit capacity,higher performance requirements of wind power pitch control are put forward.In order to further improve the performance of wind power pitch control,this thesis innovatively applies fractal interpolation wind speed prediction to wind power pitch control optimization.The main contents of this thesis are as follows:1.Introduce the basic principle of wind power pitch control,analyze the components of the wind power system,and build a 2MW wind power mathematical model on the Simulink,which provides a simulation platform for the follow-up research.2.Use Empirical Mode Decomposition(EMD)and Hilbert Transform(HT)to analyze the theoretical feasibility of the application of fractal interpolation in wind speed prediction.Compile and run the classical fractal interpolation prediction program on MATLAB.In order to improve the wind power pitch control performance under the guidance of subsequent fractal interpolation prediction,the wind speed prediction algorithm composed of classical fractal interpolation is improved.The analysis of historical vertical scale factor change sequence is added to the classical fractal interpolation prediction algorithm,and the future trend of vertical scale factor is predicted through BP neural network.The simulation results verified that the prediction performance of the improved fractal interpolation prediction algorithm is better than that of the classical fractal interpolation prediction algorithm and the explicit fractal interpolation prediction algorithm.These works above provided subsequent pitch control research an improved fractal interpolation wind speed prediction algorithm.3.The improved fractal interpolation wind speed prediction algorithm is applied to guide the pitch control of doubly fed induction generator(DFIG).Based on the wind speed step response of DFIG,the different effects of predictive pitch control,feedforward pitch control and feedback pitch control are studied with the consideration of the power loss.Combined with the improved fractal interpolation wind speed prediction algorithm,two improved wind power pitch control methods based on fractal interpolation prediction are proposed.In the first method,time domain leading pitch control can improve power stability and avoid DFIG speed overspeed effectively.In the second method,the fuzzy PI pitch control based on wind speed prediction can improve the dynamic tracking performance of DFIG power.Finally,the two improved methods are simulated by the wind power mathematical model built on the Simulink platform.The simulation results show that the two improved methods can effectively improve the performance of feedforward feedback pitch control from two aspects of rotation speed and output power,and improve the stable operation of DFIG.