When the sub-synchronous oscillation (SSO)occurs in the power grid, the performance of the converter of doubly-fed wind power system is disturbed, which affects the stability of the power generation system. To address this problem, this paper firstly establishes a mathematical model of doubly-fed wind power system taking into account the phase perturbation, combs the mechanism of grid sub-synchronous oscillation perturbation on doubly-fed wind power system, and divides the perturbation into physical perturbation as well as error perturbation; secondly, the improved phase-locked loop is designed to eliminate the adverse effect of the phase-induced error perturbation on the doubly-fed wind power system; and lastly, the quasi-resonant controller is improved by using the frequency adaptation algorithm, so as to suppress the disturbance caused by different frequencies of the physical perturbation of the converter of doubly-fed wind power system. Finally, a frequency adaptive algorithm is used to improve the quasi-resonant controller to suppress the oscillating power output of the doubly-fed wind power system caused by the physical perturbations at different frequencies.