Study On The Stall And Pitch Hybrid Control Of Permanent Magnet Direct Drive Wind Turbine

Wind energy,as a kind of low development cost,clean and safe renewable energy has attracted more and more attention from all walks of life and has become a hot topic of research.Compared to other clean new energy sources that can be obtained stably,wind energy has low energy density and poor stability.With the different seasons and climates,the speed and direction of the wind are randomly changing.Therefore,while vigorously developing the use of wind energy,the demand for reliability and efficiency of wind turbines are also increasing.Because of the characteristics of high efficiency,high reliability,small overall weight of the unit,and easy and effortless maintenance,permanent magnet direct-drive wind turbine is gradually recognized by professionals.At present,the power control of permanent magnet direct drive wind turbine is mainly pitch control,and constant power operation above the rated wind speed is achieved by adjusting the pitch angle.However,the pitch adjustment requires an independent control system,which virtually increases the complexity of the system.Frequent movement of the pitch angle results in a relatively high failure rate.According to the data released by the SERC's wind power safety supervision report,the failure probability of the wind turbine pitch system in the first eight months of 2011 was more than 40 percent.Aiming at the defects of the existing technology,this paper takes the 60 kW permanent magnet direct drive wind turbine of Ghrepower as the research object,and proposes a stall and pitch hybrid control strategy.This method is an organic combination of stall control and pitch control.When the wind turbine is running at low wind speed,the generator speed is less than the rated speed,and the maximum power tracking strategy is adopted;when the wind turbine is above the rated wind speed,the wind turbine blades are turned to a certain angle through the pitch to increase the attack angle,and the blades are stalled,so that to maintain stable power output.The pitch rate of the stall and pitch hybrid control strategy may be less than the pitch rate of the pitch control.The pitch angle of the blades only need to be fine-tuned to maintain the rated power output,and the stroke of the pitching mechanism is also much less than the pitch control.While ensuring the stable output of power,the flexibility of the transmission system is effectively improved,and the failure rate of the pitch changing mechanism is reduced.This project is based on the authority of the wind power industry auxiliary design and calibration software GH Bladed simulation platform,according to the real data of 60 kW stalled permanent magnet direct drive wind turbine to build the model,and uses C++ to write control program.The GH Bladed software calls an external control program for simulation experiments.The simulation results show that the stall and pitch hybrid control of the permanent magnet direct drive wind turbine can maintain the rated power output when the wind turbine is at high wind speed,and the effect is better than the pitch control.