Research On Lvrt Control Strategy Of DFIG Wind Energy Conversion System Based On Stator Flux Linkage Tracking

With the increasing demand for energy,Some issues about the globalization of energy also gradually appear,for instance,energy depletion due to non-renewable fossil fuels,environmental pollution caused by a large number of SO₂,CO and dust,smoke and other,and global warming caused by the increase of CO₂ and other greenhouse gases.So the development of renewable energy has become the main goal of the energy revolution.Wind energy resources which are heir abundant and renewable energy in the world have been paid more and more attention.The wind power generation technology,which converts wind energy into electric energy,is paid more and more attention by domestic and foreign experts and scholars.In the modern wind power generation technology,because the doubly fed induction generator?DFIG?is easy to control and stable running,the DFIG wind power generation system has been widely used.With the increase of wind power installed capacity,for the requirement of parallel operation of unit is more and more strict with the specification of power grid,this is mainly embodied in the power grid fault,DFIG unit is able to connect to the grid,to realize low voltage ride through?LVRT?.In this paper,the DFIG wind power system converter is taken as the research object,and LVRT of DFIG is studied deeply during the power grid fault.The rotor side converter?RSC?of the DFIG wind power generation system is a part of the whole system which can be controlled.It is the key method to realize the LVRT of the DFIG unit when the fault occurs in the power grid,and the hardware protection is not used that RSC is controlled reasonablely.Firstly,in this paper,in different coordinate system,the DFIG mathematical model is established,on this basis,a low voltage DFIG control strategy based on stator flux tracking is proposed,the principle and realization method of this control strategy are detailed introduced,and the effect of control parameters on the control strategy is analyzed.Secondly,the influence of symmetric drop and asymmetric drop of the grid voltage to DFIG is also analyzed,including the transient process of stator flux,the transient response of the stator current and the rotor voltage.Finally,the proposed control strategy is verified by the MATLAB/Simulink software,built the experimental platform of a doubly fed induction generator wind power generation system,the proposed control strategy of the rotor side converter is researched on this platform.The simulation results and experimental results show that the proposed control strategy is effective.