Research On Variable Pitch Control System Of Permanent Magnet Direct Drive Wind Turbine

With the shortage of fossil fuels such as coal and increasing pollution,it is urgent to seek clean and alternative energy.As a green and pollution-free energy,wind energy is widely distributed and rich in resources.However,in the actual operation of the wind turbine,wind conditions such as wind shear and tower shadow effect will cause uneven load distribution on the blades,causing blade flapping vibration and torque fluctuation problems,affecting the stability of the wind turbine output power and power quality.At the same time,the pitch method of the motor acceleration and deceleration unit will lose part of the transmission efficiency,accompanied by noise,vibration and safety problems.In order to make wind energy have a higher competitive advantage in the market and increase the rate of wind energy capture,this paper studies the permanent magnet direct-drive pitch control method with the support of Xuzhou Science and Technology Key Projects.The main research work is as follows:(1)According to the influence of wind shear,tower shadow effect and wind turbulence on the airflow characteristics,simulate the relationship between wind speed and blade radius;based on the leaf element-momentum theory to derive the relationship between the induced factor and the change of wind speed and leaf element Force condition: Combining the pitch angle,wind energy utilization rate and coupled wind speed to simulate the blade load,obtain the required pitch torque when the wind speed changes,and provide effective load data for the subsequent design of the pitch system.(2)Based on the vector control mode with id=0,perform PI controller parameter calculation and simulation debugging on the current loop,speed loop,and position loop,and select appropriate PI control parameters;in order to improve system robustness and restrain external interference Ability to design interference observers for speed loops;build a three-closed-loop permanent magnet direct-drive vector control model,simulate and verify PI controllers and interference observers,and achieve relatively ideal control effects.(3)Aiming at the working environment of permanent magnet direct drive variable pitch,low speed and high torque,the system design of the variable pitch permanent magnet direct drive control system is carried out.The hardware system includes processor structure,control board power supply mode,interface and signal processing circuit,digital signal isolation drive circuit,voltage protection circuit and analog quantity acquisition circuit;the main program of the software system mainly realizes the initialization of each module,control method,and signal acquisition,Fault protection,etc.are realized in the interrupt program.(4)Use a magnetic particle dynamometer to simulate the load required during pitch change,build an experimental platform for the pitch permanent magnet direct drive control system,and verify the speed control through the direct drive drag load.Experiments show that the control system has good response performance to sudden load and slowly varying load,and each control parameter is within the allowable error range,indicating that the variable pitch permanent magnet direct drive system meets the actual control requirements.This paper has a total of 71 pictures,5 tables,and 86 references.