Abstract: Aiming at the failure of traditional voltage sag source location method in complex grid structure and multi-disturbance source type scenarios,a voltage sag source location method based on positive sequence component phase difference is proposed. Firstly,the superposition principle of linear circuit is used to analyze active power transmission rule under the action of disturbance source is analyzed,and the difference of power transfer mode when the relative position of voltage sag source is different is characterized by the phase difference between voltage and current. Secondly,by introducing instantaneous symmetric component method,the location criterion of voltage sag source is obtained which is not affected by disturbance source types. Finally,the accuracy and effectiveness of proposed method are verified by simulation and field cases.