Abstract：With the increasing scale of new energy power generation and the continuous reduction of lithium

battery cost，energy storage technology has gradually become an important supporting technology to achieve the

goal of "double carbon". However，the state of charge（SOC）of the energy storage system is too high or too low，

which will affect its service life. It is necessary to avoid overcharge or overdischarge of the energy storage system

through control strategies. Therefore，the SOC control strategy of energy storage system based on envelope（ENE）index was proposed. Based on the analysis of the track trend of ENE index in stock price analysis，the change trend f SOC direction during the operation of energy storage system is keenly aware. When the SOC offset exceeds the safe range and the change rate is too fast，control measures are taken to avoid overcharge or overdischarge. The simulation results show that the strategy proposed can effectively identify the risk of too high or too low SOC in the process of energy storage participating in peak shaving and frequency modulation，and take preventive measures in time to prolong the service life of the energy storage system.

      Key words：energy storage system；state of charge（SOC）；ENE index；control strategy