Research On Variable Pitch Control Technology And Semi-physical Simulation Test For Large Wind Turbine

Because of its characteristics of clean,renewable and low cost,wind energy accounts for an increasing proportion of other alternative new energy sources,which provides a good solution to the ecological pollution caused by the combustion of traditional fossil energy.Due to the randomness of the wind speed and complex nonlinear control system of wind turbine,the change of wind speed can lead to the output power of the wind turbines can’t maintain a stable near the rated power.How to obtain relatively stable’s output power of wind turbine under the condition of the real wind speed is higher than the rated wind speed has become the hot issue of research areas of many experts and scholars.At present,the widely used variable pitch controller in wind farms is PID controller.Although the controller has a simple structure and reliable operation,it is difficult to meet the needs of wind farms for actual fan power accuracy under complex wind conditions.Based on this background,the running state of the wind turbine and the variable pitch angle control algorithm are the main research objects.The main research content includes: the establishment of mathematical model for large wind turbine,the design and implementation of fuzzy adaptive PID,the second order nonlinear active disturbance rejection control(Active Disturbance Rejection Control,ADRC)and the linear active disturbance rejection control,the construction and algorithm validation of the semi-physical simulation platform based on programmable logic controller.First of all,on the basis of detailed analysis and understanding dynamic model of wind turbine,the wind generators is difficult to keep rated output power above the rated wind speed.In order to solve this problem,proposing the method of combining fuzzy control and PID control and establishing the unit model with fuzzy PID controller.The control method has the advantages of fuzzy control without the need to establish an accurate mathematical model and high precision of PID.By applying different simulated wind speed,the simulation results show that the fuzzy adaptive PID in response speed and decrease overshoot is better than PID control effect.Then,aiming at the problem of strong nonlinearity and unknown disturbance in wind power generation system,ADRC is applied to the control process of variable pitch in wind power generation system.In order to solve the problem of parameter multi-setting difficulty in second-order ADRC controller,introducing the concept of bandwidth to reduce the number of unknown parameters,achieving the variable pitch linear ADRC of wind turbine.The simulation results show that,compared with PID and fuzzy adaptive PID control,the variable pitch ADRC control of wind turbine is more effective.Its response speed is faster,overruns are smaller and steady-state accuracy is higher.Finally,through the construction of the semi-physical simulation platform and the writing of the algorithm program,combined with the specific wind speed data input,the effectiveness and feasibility of ADRC control algorithm in reducing the fluctuation of the output power of the wind turbine above the rated wind speed were verified,so as to maintain the safe and stable operation of the unit.