The grid-connected performance of grid-side converters in wind power generation system depends on high-performance synchronous detection system, the quick and accurate extraction of synchronizing signal under power grid fault in especial. A novel phase locked loop based on second-order generalized integrator （SOGI） is proposed, which eliminates the influence of the unbalanced and distorted grid voltage in the dq transform, as well as that of the second-order and higher order harmonic components, realizing the detection of synchronizing signal of the fundamental voltage. MATLAB simulation and experimental results show that the frequency, phase angle and positive and negative sequence components can be obtained quickly and efficiently.