Research On Primary Frequency Regulation Coordinated Control Strategy Of Direct Drive Permanent Magnet Wind Turbine

In recent years,with the increasing penetration of wind turbine in the power grid,the impact on the grid becomes more and more obvious.Due to the wind turbine operating at maximum power tracking model,it effects the output power of wind turbines that cannot respond to the changes of power grid frequency,at the same time the reserve power of primary frequency regulatioan will reduce,the power grid frequency stability issues become more prominent.Therefore,this paper makes a comprehensive analysis of primary frequency control strategy,and put forward the coordinated control strategy of overspeed control and pitch angle control,applied in the primary frequency control system of direct drive permanent magnet wind turbine.Firstly,This paper introduces the basic theory of primary frequency regulation,analyzing the relative factors to the influence of the primary frequency regulation,and then studies and analyzes the theory and the model of variable speed wind turbines participation in primary frequency regulation in the power system.Secondly,analyzing the operation principle of the direct drive permanent magnet wind turbine generator,and the mathematical model of direct drive permanent magnet wind turbine generator is presented.Based on the paper analyses the generator rotor flux oriented vector control strategy,the grid side converter of grid voltage orientation control strategy and pitch angle control strategy,which has laid a theoretical foundation for the study of primary frequency control strategy of wind turbine.Then,in order to make the direct drive permanent magnet wind turbine with the ability of primary frequency regulation.In this paper,applying the coordinated control strategy of the speed and the pitch angle.According to the different conditions of the wind speed,the wind speed can be divided into three modes of low wind speed,middle wind speed and high wind speed.In the mode of low wind speed,control strategy is the combination of switching to 90%maximum power curve and droop control.In the middle wind speed,the coordinated control strategy is combining the speed and pitch angle.In the high wind speed,control strategy is the combination of switching to 90%maximum power curve and pitch angle.Finaly,simulating the coordinated control strategy and the traditional combination control stratergy in the PSCAD/EMTDC.The simulation results show that in the low wind speed model,relying on speed control of decreasing load and need to 6s to a state of equilibrium;In the middle wind speed model,because of the speed and the pitch angle control at the same time,the dynamic transition need to 4s;in the high wind speed model,only through adjust the pitch angle change active power output,wind turbine needs 1.2s to a new steady-state operating point.