Research On Wind Speed Detection And Pitch Control Strategy Of Wind Turbines

The continuous development of wind power has gradually developed towards the large-scale and light-weight of wind turbines.The wind power generation system is a nonlinear,strongly coupled system with instability and randomness.Therefore,it is important to optimize the control strategy of the wind power pitch control and study more efficient and intelligent control technology to achieve safe,efficient and stable operation of the wind turbine.Under the background of this research,the optimization of pitch control is taken as the research goal.The thesis expounds the pitch control principle and pitch control strategy of the wind turbine,and models the 2MW wind turbine.Simulation experiments are carried out in MATLAB / Simulink simulation software.PID pitch control and fuzzy PID pitch control are adopted.The simulation results show that under the fuzzy PID pitch control strategy,no matter under the conditions of gust,step wind and turbulent wind,the control accuracy is high,the adjustment time is short,and the power output of the wind turbine is more stable than PID control.For the equipment-free research,the control scheme containing wind measurement lidar(Li DAR),a strategy for simulating lidar measurement of wind speed based on the transformation method of radar coordinate system and wind coordinate system is proposed.The simulation results show that: under this strategy,it can be equipment-free The wind measurement lidar control scheme is used to provide simulation conditions.In view of the random disturbance of wind speed and the non-linearity and time lag of wind turbines,the output power of wind turbines fluctuates.A control strategy of Li DAR-P(proportional)+ ELM(Extreme Learning Machine)is proposed,which puts wind turbines at rated wind speed.Under the stable output value of the PI controller,use the extreme learning machine(ELM)to learn this stable output value.The wind speed measured by the lidar is input to the ELM to give it the steady state value of the control quantity,using the ratio(P)The controller adjusts the error between the speed of the wind wheel and the rated speed.Finally,the ELM output steady state value and the output value of the proportional controller are superimposed and sent to the pitchactuator together.The simulation results show that the comparison between the Li DAR-P + ELM pitch control strategy and the traditional PI control strategy has high control accuracy and short adjustment time,improves the lag of the traditional PI controller,and makes the power output of the wind turbine more stable.To improve the control strategy of Li DAR-P + ELM pitch control,and three control strategies are proposed,namely Li DAR-fuzzy ratio +ELM pitch control strategy,Li DAR-fuzzy + ELM pitch control strategy and Li DAR-fuzzy neural variable The paddle control strategy,in which the Li DAR-fuzzy neural pitch control strategy takes the error of the wind wheel speed and the rated speed,the rate of error change and the wind speed measured by the lidar as the input of the fuzzy neural network controller,the fuzzy proportional controller output value and ELM The output values are superimposed as the output of the fuzzy neural network controller.The simulation results show that: under the Li DAR-fuzzy +ELM control strategy,the power output of the unit is more stable;under the Li DAR-fuzzy + ELM control strategy,the pitch control effect is smoother,and under the Li DAR-fuzzy neural control strategy,Li DAR is retained-The effect of fuzzy ratio + ELM control strategy,while reducing the controller algorithm.