Research On LVRT Strategy Based On Passivity Theory Of Current Source PMSG Wind Power System

With the rapid development of wind power generation systems,the penetration of the wind power into utility is becoming higher,and low voltage ride through(LVRT)technology attracts more and more attention.This paper focuses on LVRT control method for current source converter based permanent magnet synchronous generator wind generation system(CSC-PMSG-WGS),the main research contents and outcomes of the paper are as follows:1.Through analyzing the power fluctuation mechanisms in the system when grid voltage drop occurs,an unbalanced control method of grid-side inverter based on PR controller in ?? coordinate system is proposed,and compared with unbalanced control method based on PIR controller in dq rotating coordinate system,the contrast analysis is adopted through the simulation2.In order to improve system dynamic performance and robustness,a noval LVRT strategy based on passivity theory is proposed in this paper.By the proposed strategy,once grid voltage dip happens,generator-side converter adopts direct power control strategy based on passivity theory,which can rapidly limits output power of generator;meanwhile grid-side inverter uses unbalanced control method based on passivity theory to keep the dc current stable and eliminate the power ripples of twice times fundametal frequency.3.Interconnection and damping assignment passivity based control is introduced to generator-side and grid-side control methods,which is based on port controlled hamiltonian with dissipation system.Then,this paper deduces and analyzes the controller design of generator-side and grid-side converter4.Simulation models of the CSC PMSG-WGS are established in Matlab/Simulink.And the low-voltage ride-through capability of the proposed control strategy under different grid voltage drop conditions is verified,simulation results indicate that proposed strategy can significantly improve the system response speed and suppress power fluctuation caused by negative components of grid voltage.In addition,the reliability and efficiency of LVRT strategy based on PIR controller is verified by the experiments based on the hardware platform,the experimental results show that LVRT strategy based on PIR controller can eliminate power fluctuation and keep DC-link current stable,which realize the predetermined control target.