Method and device for calibrating SOC at tail end of charging or discharging of energy storage system

1 . A method for calibrating a State of Charge (SOC) at a tail end of charging or discharging of an energy storage system, comprising:

acquiring battery parameters of a battery unit during charging or discharging of the battery unit, wherein the battery parameters comprise an SOC and a voltage;

acquiring a pre-calibrated calibration SOC at the tail end of charging or discharging and a corresponding calibration voltage;

determining whether the battery unit meets an SOC calibration condition, by comparing the SOC of the battery unit with the calibration SOC and comparing the voltage of the battery unit with the calibration voltage; and

calibrating the SOC of the battery unit to the calibration SOC, in responding to determining that the battery unit meets the SOC calibration condition,

wherein the determining whether the battery unit meets an SOC calibration condition comprises: determining that the battery unit meets the SOC calibration condition during charging of the battery unit, in response to the SOC of the battery unit being less than the calibration SOC and the voltage of the battery unit being greater than the calibration voltage.

2 . The method according to claim 1 , wherein acquiring the pre-calibrated calibration SOC at the tail end of charging or discharging and the calibration voltage comprises:

selecting the calibration SOC corresponding to a charging state or a discharging state of the battery unit, and a voltage and a current that are corresponding to the calibration SOC, from a pre-determined battery voltage curve under a standard operating condition; and

calibrating the voltage corresponding to the calibration SOC, based on a current of the battery unit, an internal resistance of the battery unit, and the current corresponding to the calibration SOC, to obtain the calibration voltage.

3 . The method according to claim 1 , wherein determining whether the battery unit meets the SOC calibration condition during charging of the battery unit comprises:

determining whether the SOC of the battery unit is less than a sum of the calibration SOC and a charge calibration return difference threshold, wherein the charge calibration return difference threshold is a negative value;

determining that the battery unit does not meet the SOC calibration condition, in response to the SOC of the battery unit being not less than the sum of the calibration SOC and the charge calibration return difference threshold;

determining whether the voltage of the battery unit is greater than the calibration voltage, in response to the SOC of the battery unit being less than the sum of the calibration SOC and the charge calibration return difference threshold;

determining that the battery unit does not meet the SOC calibration condition, in response to the voltage of the battery unit being not greater than the calibration voltage;

determining that the battery unit meets the SOC calibration condition, in response to the voltage of the battery unit being greater than the calibration voltage.

4 . The method according to claim 3 , wherein the voltage of the battery unit is a highest voltage of voltages of cells in the battery unit during charging of the battery unit.

5 . The method according to claim 1 , wherein determining whether the battery unit meets the SOC calibration condition during discharging of the battery unit comprises:

determining whether the SOC of the battery unit is greater than a sum of the calibration SOC and a discharge calibration return difference threshold, wherein the discharge calibration return difference threshold is a positive value;

determining that the battery unit does not meet the SOC calibration condition, in response to the SOC of the battery unit being not greater than the sum of the calibration SOC and the discharge calibration return difference threshold;

determining whether the voltage of the battery unit is less than the calibration voltage, in response to the SOC of the battery unit being greater than the sum of the calibration SOC and the discharge calibration return difference threshold;

determining that the battery unit does not meet the SOC calibration condition, in response to the voltage of the battery unit being not less than the calibration voltage;

determining that the battery unit meets the SOC calibration condition, in response to the voltage of the battery unit being less than the calibration voltage.

6 . The method according to claim 5 , wherein the voltage of the battery unit is a lowest voltage of voltages of cells in the battery unit during discharging of the battery unit.

7 . A device for calibrating a State of Charge (SOC) at a tail end of charging or discharging of an energy storage system, comprising:

one or more processors; and

a memory, the memory storing computer-readable instructions, and the computer-readable instructions, when executed by the one or more processors, causing the one or more processors to:

acquire battery parameters of a battery unit during charging or discharging of the battery unit, wherein the battery parameters comprise an SOC and a voltage;

acquire a pre-calibrated calibration SOC at the tail end of charging or discharging and a corresponding calibration voltage;

determine whether the battery unit meets an SOC calibration condition by comparing the SOC of the battery unit with the calibration SOC and comparing the voltage of the battery unit with the calibration voltage; and

calibrate the SOC of the battery unit to the calibration SOC in responding to determining that the battery unit meets the SOC calibration condition,

wherein during charging of the battery unit, the computer-readable instructions further cause the one or more processors to: determine that the battery unit meets the SOC calibration condition, in response to the SOC of the battery unit being less than the calibration SOC and the voltage of the battery unit being greater than the calibration voltage.

8 . The device according to claim 7 , wherein the computer-readable instructions further cause the one or more processors to:

select the calibration SOC corresponding to a charging state or a discharging state of the battery unit, and a voltage and a current that are corresponding to the calibration SOC, from a pre-determined battery voltage curve under a standard operating condition; and

calibrate the voltage corresponding to the calibration SOC based on a current of the battery unit, an internal resistance of the battery unit, and the current corresponding to the calibration SOC, to obtain the calibration voltage.

9 . The device according to claim 7 , wherein during charging of the battery unit, the computer-readable instructions further cause the one or more processors to:

determine whether the SOC of the battery unit is less than a sum of the calibration SOC and a charge calibration return difference threshold, wherein the charge calibration return difference threshold is a negative value;

determine that the battery unit does not meet the SOC calibration condition, in response to the SOC of the battery unit being not less than the sum of the calibration SOC and the charge calibration return difference threshold;

determine whether the voltage of the battery unit is greater than the calibration voltage, in response to the SOC of the battery unit being less than the sum of the calibration SOC and the charge calibration return difference threshold;

determine that the battery unit does not meet the SOC calibration condition, in response to the voltage of the battery unit being not greater than the calibration voltage;

determine that the battery unit meets the SOC calibration condition, in response to the voltage of the battery unit being greater than the calibration voltage.

10 . The device according to claim 9 , wherein the voltage of the battery unit is a highest voltage of voltages of cells in the battery unit during charging of the battery unit.

11 . The device according to claim 7 , wherein during discharging of the battery unit, the computer-readable instructions further cause the one or more processors to:

determine whether the SOC of the battery unit is greater than a sum of the calibration SOC and a discharge calibration return difference threshold, wherein the discharge calibration return difference threshold is a positive value;

determine that the battery unit does not meet the SOC calibration condition, in response to the SOC of the battery unit being not greater than the sum of the calibration SOC and the discharge calibration return difference threshold;

determine whether the voltage of the battery unit is less than the calibration voltage, in response to the SOC of the battery unit being greater than the sum of the calibration SOC and the discharge calibration return difference threshold;

determine that the battery unit does not meet the SOC calibration condition, in response to the voltage of the battery unit being not less than the calibration voltage;

determine that the battery unit meets the SOC calibration condition, in response to the voltage of the battery unit being less than the calibration voltage.

12 . The device according to claim 11 , wherein the voltage of the battery unit is a lowest voltage of voltages of cells in the battery unit during discharging of the battery unit.