In view of the phenomena of active power, reactive power, electromagnetic torque oscillation and grid-connected current asymmetry of doubly-fed wind power generation in grid-connected operation under unbalanced grid voltage, the mathematical model of doubly-fed wind power generator is established in positive and negative synchronous rotating coordinate system, the positive and negative sequence current instructions under three control objectives are deduced, and the new control scheme of rotor-side converter based on proportional-integral-resonance controller is proposed which makes up for the shortcoming of traditional control strategy that voltage unbalance fault affects system stability, simplifies the control system structure and enhances the Fault-Crossing ability of doubly-fed wind turbines. The feasibility and effectiveness of the control strategy are verified by MATLAB/Simulink simulation.