Power Control And Load Analysis Of Wind Turbine

Under the background of increasing energy demand,domestic attention to energy structure is also increasing.As a new energy power generation industry,the important position of wind power generation is ineffable.With the rapid development of wind power technology,the new problems that need to be faced are the power control problem and unbalanced load problem caused by the increase of installed capacity,blade length and tower height of wind turbine,and the maximum power tracking problem of low wind speed resources.At low wind speeds,many scholars have solved the problem of maximum wind energy capture from the perspective of control methods.Few studies have been conducted on the point that the wind turbine response with a certain delay error in the control process will affect the tracking of the best control target.At high wind speeds,most scholars focus on power control or load control to make specific analysis,and less on load analysis based on control methods.In order to solve the above problems,the main work of this paper is as follows :(1)In the analysis of wind turbine energy conversion and wind energy absorption,and improve the utilization of wind energy and high wind speed to maintain constant power output,the paper takes 1.5 MW horizontal axis wind turbine as the research object,the wind turbine model control research,and build the relevant sub model and wind speed model of the unit,for the back of the low wind speed maximum power tracking and high wind speed variable pitch control design foundation.The submodels include wind turbine model,transmission system model,generator model and pitch actuator model.(2)When the wind speed is lower than the rated wind speed,the common control method has some shortcomings in maximizing the utilization of wind energy.From the point of view of reducing the delay error in the control process of the unit,considering that the measured wind speed is nonlinear and time-varying,the empirical mode decomposition(EMD)method is adopted to decompose the measured wind speed of the wind farm.Reduce the fluctuation of wind speed with time,then optimize the short-term wind speed prediction model of BP neural network(BPNN)by genetic algorithm(GA),and sum the predicted values of each component to get the predicted wind speed.On this basis,the optimal speed of the generator is obtained in advance by using the optimal tip speed ratio method,and the fuzzy PID controller is used to improve the control effect.The simulation results show that the maximum capture of wind energy can be achieved by adding the predictive wind speed model.(3)Aiming at the shortcomings of unified pitch control and independent pitch control of common control algorithm in constant power stability output and load reduction,an independent pitch control strategy based on azimuth weight coefficient distribution of grey fuzzy PID is proposed.As the power of the generator set is related to the change of wind speed and pitch angle,the control effect will be improved through the improvement of the controller and pitch actuator.Fuzzy control belongs to ex post control,and grey prediction can solve the problem of overshoot and accuracy in ex post control.In addition,the reliability of grey prediction is high,the prediction result is accurate,and there is no need to consider the accuracy of the controlled object,so the grey prediction method of prior control is introduced into the independent variable pitch fuzzy PID controller of wind turbine.The simulation experiments are compared with the grey fuzzy PID unified pitch control and fuzzy PID independent pitch control under the wind turbine.It can be seen from the simulation results that the control strategy can improve the overshoot and jitter amplitude of the generator compared with the other two,and finally stabilize the output at a constant value.(4)Because the model established by the simulation software is idealized,it can not accurately represent the wind turbine,and the load calculation is often carried out by GH Bladed software.Therefore,based on the blade element momentum theory in aerodynamics,the paper models the 2MW wind turbine,generates a separate external control dynamic link file(DLL)in the simulation software,and then imports the external control DLL file into the control system in the GH Bladed software,and calculates the load of the blade and hub under the grey fuzzy PID independent variable pitch control strategy.Compared with the fuzzy PID independent pitch control strategy,the performance of the controller in reducing the load is verified.The simulation results show that this method can obviously reduce the unbalanced load of the fan blade and achieve the effect of reducing the load fluctuation.