Battery energy storage system SOC tail end calibration method

The invention provides a battery energy storage system SOC tail end calibration method, which comprises the steps that when an EMS calibrates the SOC for a BMS, the charging/discharging power given value of the BMS is increased, and the charging/discharging SOC upper limit and the charging/discharging SOC lower limit of the BMS are increased; and after the battery of the BMS is fully charged and emptied for a cycle, the ampere-hour electric quantity of the complete charging/discharging of this round and the current effective ampere-hour electric quantity of the battery are used for solving the weighted average sum, and the weighted average sum result is used as the new effective ampere-hour electric quantity of the battery so as to complete SOC calibration. According to the method, on the basis of reserving simple calculation of the ampere-hour integral method, the problem that a traditional ampere-hour integral method is low in precision when power fluctuation is large is solved, and tail end calibration bas