SELF-SYNCHRONIZATION LVRT DUAL-MODE SWITCHING CONTROL METHOD UNDER WEAK GRID
Aiming at the transient over-voltage and over-circuit problems of self-synchronous voltage source at low voltage ride through(LVRT)in the case of weak grid,this paper derives the mathematical equations of grid impedance,angle jump and voltage drop depth,and analyzes the key factors affecting over-voltage and over-current.Then,a self-synchronous voltage source LVRT dual-mode switching control method is proposed.When the power grid is normal,the self-synchronous voltage source equalization control method based on virtual impedance is used to balance the control strength of the voltage loop and the current loop by simulating the impedance.When the grid is in the state of voltage drop,the low voltage ride through mode based on strong current control can effectively improve the smooth transition ability of voltage drop transient,low voltage ride through process and voltage recovery stage.At the same time,in order to further suppress the voltage and current transients in the transition process,a voltage recovery control strategy based on multi-state feedback follower is proposed,and the transient overcurrent impact is suppressed by the phase mutation compensation control strategy to help the network voltage repair.Finally,the feasibility and superiority of the control method are verified by Matlab/Simulink modeling and simulation software.
self-synchronous voltage sourceshort circuit ratiolow voltage ride throughvirtual impedancemulti-state feedback
万方数据
维普
