Abstract: The stability of the distribution network is directly related to the operational quality of energy storage on the end user side.A thermal runaway early warning method for user-side energy storage systems under abnormal operation scenarios in distribution networks is proposed.The method establishes a complete transmission path from the abnormal state of the distribution network to the user-side energy storage and identifies key characteristic quantities of lithium-ion battery thermal runaway,including abnormal current/voltage values and the duration of abnormal states.The study constructs a state evolution model for user-side energy storage to analyze the impact of these characteristic quantities on the safe operation state of the energy storage.Simulation results reveal the specific impact of different abnormal electrical quantity changes on energy storage safety,such as the high positive correlation between abnormal current/voltage values and the abnormal temperature of energy storage,and the strong positive correlation of the duration of abnormal states.Based on this,the study determines the triggering boundary for thermal runaway of user-side energy storage and formulates preventive,control,and response measures for various abnormal operation states,including single-phase grounding,two-phase short circuits,two-phase grounding,and three-phase short circuits.These measures include preparing to disconnect energy storage in case of untimely fault elimination and strengthening line protection construction.The application of this method significantly improves the safety and stability of the distribution network and user-side energy storage systems.