In order to accurately describe the impact of distance protection on voltage sag characteristic in meshed network，a novel voltage sag stochastic evaluation method was proposed with the consideration of meshed network topology characteristic and distance protection operation characteristic. Based on the operation principle of distance protection,the protection operation time was determined according to short-circuit calculation result.Comparing the operation time of distance protection at each end of the line,whether or not a fault will lead to a multistage voltage sag could be confirmed.The magnitude of multistage voltage sag was determined by modifying nodal impedance matrix,and multistage voltage sag was converted to rectangular voltage sag based on the concept of loss of voltage.The proposed method was applied to a 250-bus test system, and the simulation results showed that the proposed method could quantify the impact of distance protection operation time on voltage sag magnitude and duration,and over-estimation of multistage voltage sag could be avoid.Compared with the traditional method，the proposed method was more accordant to practical power system operating condition.
