Abstract: When the wind power enters the low voltage ride through state, it will cause active power disturbance. Nowadays, wind turbines possess excellent low voltage ride through ability and can run without off-grid operation after a fault occurs. The active power disturbance form is no longer strictly equivalent to a step; instead, it exhibits a slope recovery after the step. The current research on the system frequency quantization characteristics in the case of active slope recovery is limited. Therefore, the introduction of wind power into the closed-loop frequency model is performed on the basis of simplifying the frequency closed-loop model of the power system, and the model is simplified to an open-loop one by fitting function method. The analytical expression of the maximum frequency variation is then derived through the open-loop model, and the maximum wind power ratio of the system and the minimum droop coefficient of wind power participating in frequency regulation are calculated based on this expression. Finally, the effectiveness of the open-loop method and the proposed formula under the low voltage ride through of the power system with wind power is verified through simulations using Matlab/Simulink and PSCAD/EMTDC electromagnetic transient simulation software.