The activation of crowbar protection will change the doubly-fed induction generator (DFIG) stator and rotor flux coupling process and its coupling strength during the low voltage ride-through (LVRT) period

which will affect the dynamic attenuation of the unit fluxes and the crowbar protection performance. Facing this problem

this paper proposes a kind of flux coupling coefficients to characterize the induction effect between stator flux and rotor winding

which deals with the flux transient coupling process of generator following a grid fault as the superposition of different states

while analyzing the coupling laws of crowbar resistance on the amplitude and phase angle of the positive sequence

negative sequence

as well as transient reverse ac rotor induction flux component. On this basis

the dynamic response of the motor rotor flux is described by the rotor flux space vector diagram and vector locus. Finally

an optimal configuration method of crowbar resistance is proposed based on the principle of rotor flux amplitude ratio and the optimum inclination angles to deal with the grid asymmetrical faults

which can weaken the DFIG transient response due to improper flux coupling while effectively improving the reactive power characteristics and transient performance of the unit. The correctness of the proposed theoretical analysis and method is verified using MATLAB/Simulink simulation software. This work is supported by Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) of China (No. 20130181110004) and Science and Technology Support Program of Sichuan Province (No. 2013GZ0062).