With the continuous integration of large-scale new energy，the scale of power grids and distribution networks is constantly expanding.Due to the large number of power electronic devices in the grid，the traditional fault line selection scheme for small current grounding systems can hardly ensure the line selection accuracy.To solve this problem， the fault characteristics of active distribution networks with energy storage power stations when single-phase grounding faults occur are analyzed，namely the different fault characteristics during the charging and discharging of energy storage power stations and the distribution characteristics of single-phase grounding fault current in resonant grounding systems.Then，a fault line selection method that actively injects characteristic electrical quantities based on the control strategy of energy storage power stations is proposed.Then，a detailed analysis and research on the injection quantity frequency selection method suitable for high-precision fault line selection is conducted，including the control strategy of energy storage power stations and its parameter selection principle.Finally，a line selection criterion based on the 10 Hz component in the zero-sequence current is proposed.The PSCAD/EMTDC simulation verifies the effectiveness of the energy storage power station control strategy，the correctness of the fault line selection theory，and the effectiveness of the scheme implementation.