The operation state of the wind turbine is intimately tied to the grid-connected point voltage. Under different operation states, the control strategy and output response characteristics of wind turbines are obviously distinct, which significantly impacts the overall security and stability of the system. For different alternating current (AC) voltage dip scenarios, the impact of voltage dip on the output characteristics of wind turbines is evaluated from the aspects of voltage dip amplitude, dip duration, and dip rate. The operation states of wind turbines are divided into normal operation state, low voltage ride-through (LVRT) operation state and off-grid operation state. Furthermore, building upon the requirements of LVRT of wind turbines, a quantitative analysis method of LVRT safety of wind turbines based on the voltage trajectory of grid-connected point is proposed. The LVRT safety of wind turbines under normal operation is evaluated by the distance between the lowest point of voltage and the critical voltage of LVRT. For wind turbines in LVRT state, a quantitative analysis method that takes into account the two dimensions of voltage dip amplitude and dip duration is introduced. Finally, a simulation test example with wind turbines based on PSCAD/EMTDC is constructed to validate the quantitative evaluation ability of the proposed quantitative analysis method for the LVRT safety of wind turbines.