| In the current grid-connected system of wind power generation,variable speed and constant frequency technology has become the mainstream market technology with its advantages of maximum wind energy tracking control and small capacity of converter.Although the electromechanical control theory of doubly-fed wind power generation system is more complex,it has been mature so far,and the motor can realize better speed regulation effect.However,with the development of technology,the wind turbine becomes larger and larger.With the increase of the rotary inertia of the wind turbine,the speed of speed regulation and the efficiency of wind energy capture decrease.The main purpose of this paper is optimizeing the traditional wind capture to adapt to the large inertia characteristics of large wind power systems and the variable fluctuation characteristics of real wind speedand control strategy,This method can improve the wind energy utilization efficiency,which is of great practical significance.This paper firstly analyzes the three kinds of classic,the principle of the maximum power tracking strategy implementation requirements and the advantages and disadvantages and limitations of traditional climbing method.On this basis,this paper proposes a climbing method optimization strategy based on wind speed prediction.In this strategy,ultra-short term wind speed prediction and the tip speed ratio control are used to improve the variable step climbing method.Making trend analysis on the results of wind speed prediction,making corresponding decisions and modifying the disturbance applied by traditional mountain-climbing method,in order to improve under the trend of wind speed change tracking speed and reduce the steady-state oscillation under the gentle wind.In this paper,the wind speed prediction is mainly used in the maximum power tracking control,for which detailed wind speed signal have little significance for wind energy.So we design a by wavelet decomposition and single refactoring to grasp the trend of wind speed sequence method,again through the ARIMA model to predict the future trend of wind speed data of a few seconds,so that they can better predict trend of wind speed signal.In this paper,a mathematical method is used to evaluate the predicted results of wind speed trend.The variance and slope are used as two criteria to judge whether the wind speed in the future belongs to a stable or obvious increase/decrease trend.The optimization characteristic of mountain-climbing method makes its response speed slow in the face of large-scale changes in wind speed,and the speed tracking performance of the large inertia system lags further.Therefore,this article designed a wind speed under the obvious change trend of the future use of tip speed ratio control strategy,estimate the tip speed ratio of the stator active power points corresponding to the largest value,so that they can make large fan of early find near MPP,to accelerate the convergence speed of climbing method.This paper analyzes the reasons for the large oscillation of the steady-state operating point in the system,and proposes that the introduction of the steady-state coefficient can reduce the calculation results of the amplitude of the disturbance step near the steady-state operating point so as to reduce the steady-state oscillation and reduce the fluctuation of wind power output.Finally,the realization process of this algorithm is introduced in detail,and a method of parameter selection is introduced in this paper,and the feasibility of this strategy is verified by experiments.It was found that with the addition of prediction and tip ratio control,the dynamic response ability of tip ratio control could be obtained in the face of the rapid change of wind speed,and the speed could be followed quickly without the need for the above tip ratio set value to be completely consistent with the actual system.In the face of gentle wind speed can reduce the steady state oscillation,make the output more stable. |
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