Energy storage equipment battery pack equalization method and energy storage equipment control system

Abstract

The invention relates to an energy storage equipment battery pack equalization method and an energy storage equipment control system. The method comprises the following steps: when the energy storage equipment works, acquiring current accumulated charging energy in the energy storage equipment, and determining an equalization condition of the energy storage equipment according to the current accumulated charging energy; confirming a charge-discharge state and a cluster SoE value of the energy storage equipment, and determining an equalization mode of the energy storage equipment according to the charge-discharge state and the cluster SoE value of the energy storage equipment; and balancing the battery pack in the energy storage equipment according to the balancing condition of the energy storage equipment and the balancing mode of the energy storage equipment. The balancing efficiency can be improved, and the energy utilization rate of the energy storage system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage devices, and more specifically, to an energy storage device battery pack equalization method and an energy storage device control system. Background Art

[0002] At present, in order to improve the space utilization rate of the energy storage system, the capacity of the battery cells is getting higher and higher, and the number of battery cluster strings is getting more and more. Due to the long-term operation of the energy storage system, the environments of each battery pack are inconsistent, resulting in a larger and larger difference in the capacity of the battery cells in the battery cluster after running for a period of time. At this time, the BMS equalization technology needs to be used to reduce the difference in the capacity of the battery cells. The common methods include two schemes of passive equalization and active equalization. The passive equalization current is small, resulting in a long equalization time and unable to respond to the system requirements in a timely manner. For the active equalization scheme, the industry has not formulated corresponding specifications and standards, and the hardware schemes and software algorithms adopted by each manufacturer are different, and the equalization effects vary greatly.

[0003] At the same time, in the currently common equalization schemes, the equalization conditions and equalization strategies are both relatively single, and it is difficult to guarantee the equalization efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an energy storage device battery pack equalization method and an energy storage device control system for the above-mentioned partial technical defects of the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problems is: constructing an energy storage device battery pack equalization method, including:

[0006] When the energy storage device is working, obtaining the current cumulative charging energy in the energy storage device, and determining the equalization condition of the energy storage device according to the current cumulative charging energy;

[0007] Confirming the charge and discharge state and the cluster SoE value of the energy storage device, so as to determine the equalization mode of the energy storage device according to the charge and discharge state and the cluster SoE value of the energy storage device;

[0008] Equalizing the battery pack in the energy storage device according to the equalization condition of the energy storage device and the equalization mode of the energy storage device.

[0009] Preferably, in the embodiment of the energy storage device battery pack equalization method of the present invention, the obtaining the current cumulative charging energy in the energy storage device, and determining the equalization condition of the energy storage device according to the current cumulative charging energy; includes:

[0010] When the current cumulative charging energy is greater than a first preset value, using the voltage parameter corresponding to the energy storage device as the equalization condition of the energy storage device;

[0011] When the current cumulative charging energy is less than or equal to the first preset value, the SoE parameter corresponding to the energy storage device is used as the balancing condition for the energy storage device.

[0012] Preferably, in an embodiment of the battery pack balancing method for an energy storage device of the present invention, the charging and discharging state of the energy storage device and the cluster SoE value are confirmed to determine the balancing mode of the energy storage device according to the charging and discharging state of the energy storage device and the cluster SoE value; including:

[0013] When the energy storage device is in the charging state, judge the cluster SoE value corresponding to the energy storage device;

[0014] When the cluster SoE value is greater than or equal to the second preset value, set the balancing mode of the energy storage device to the extreme value balancing mode;

[0015] When the cluster SoE value is less than the second preset value, set the balancing mode of the energy storage device to the efficiency balancing mode.

[0016] Preferably, in an embodiment of the battery pack balancing method for an energy storage device of the present invention, the charging and discharging state of the energy storage device and the cluster SoE value are confirmed to determine the balancing mode of the energy storage device according to the charging and discharging state of the energy storage device and the cluster SoE value; including:

[0017] When the energy storage device is in the discharging state, judge the cluster SoE value corresponding to the energy storage device;

[0018] When the cluster SoE value is less than or equal to the third preset value, set the balancing mode of the energy storage device to the extreme value balancing mode;

[0019] When the cluster SoE value is greater than the third preset value, set the balancing mode of the energy storage device to the efficiency balancing mode.

[0020] Preferably, in an embodiment of the battery pack balancing method for an energy storage device of the present invention, the battery pack in the energy storage device is balanced according to the balancing condition of the energy storage device and the balancing mode of the energy storage device; including:

[0021] When the voltage parameter corresponding to the energy storage device is used as the balancing condition of the energy storage device and the balancing mode of the energy storage device is the extreme value balancing mode;

[0022] The balancing process of the battery pack in the energy storage device includes:

[0023] Obtain the absolute value of the first difference between the individual voltage and the average cell voltage of all cells in the battery pack within a first preset duration, sort the absolute values of the first differences in ascending order, obtain the cells with a number less than a first preset number and whose absolute value of the first difference exceeds a preset individual voltage difference threshold according to the sorting, discharge the cells with an individual voltage greater than the average cell voltage, charge the cells with an individual voltage less than the average cell voltage, and stop balancing within a second preset duration.

[0024] Preferably, in an embodiment of the battery pack balancing method for an energy storage device of the present invention, balancing the battery pack in the energy storage device according to the balancing condition of the energy storage device and the balancing mode of the energy storage device includes:

[0025] When using the SoE parameter corresponding to the energy storage device as the balancing condition of the energy storage device and the balancing mode of the energy storage device is the extreme value balancing mode;

[0026] The balancing process of the battery pack in the energy storage device includes:

[0027] Obtain the absolute value of the second difference between the SoE value of all cells in the battery pack and the cluster SoE value within a third preset duration, sort the absolute values of the second differences in ascending order, obtain the cells with a number less than a second preset number and whose absolute value of the second difference exceeds a preset SoE difference threshold according to the sorting, discharge the cells with an SoE greater than the cluster SoE value, discharge the cells with an SoE less than the cluster SoE value, and stop balancing within a fourth duration.

[0028] Preferably, in an embodiment of the battery pack balancing method for an energy storage device of the present invention, balancing the battery pack in the energy storage device according to the balancing condition of the energy storage device and the balancing mode of the energy storage device includes:

[0029] When using the voltage parameter corresponding to the energy storage device as the balancing condition of the energy storage device and the balancing mode of the energy storage device is the efficiency balancing mode;

[0030] The balancing process of the battery pack in the energy storage device includes:

[0031] Obtain the absolute value of the third difference between the individual voltage and the average cell voltage of some cells in the battery pack within a fifth preset duration, sort the absolute values of the third differences in ascending order, obtain the cells with a number less than a third preset number and whose absolute value of the third difference exceeds a preset individual voltage difference threshold according to the sorting, discharge the cells with an individual voltage greater than the average cell voltage, and charge the cells with an individual voltage less than the average cell voltage;

[0032] Within a sixth preset duration, obtain the absolute value of the fourth difference between the single-cell voltage and the average cell voltage of the remaining cells in the battery pack, sort the absolute values of the fourth differences in descending order, and based on the sorting, obtain cells with a quantity less than a fourth preset quantity and whose absolute value of the fourth difference exceeds a preset single-cell voltage difference threshold. Discharge the cells with a single-cell voltage greater than the average cell voltage of the cells, and charge the cells with a single-cell voltage less than the average cell voltage of the cells.

[0033] Preferably, in an embodiment of the battery pack balancing method for an energy storage device of the present invention, balancing the battery pack in the energy storage device according to the balancing conditions of the energy storage device and the balancing mode of the energy storage device includes:

[0034] When using the SoE parameter corresponding to the energy storage device as the balancing condition of the energy storage device and the balancing mode of the energy storage device is the efficiency balancing mode;

[0035] The balancing process of the battery pack in the energy storage device includes:

[0036] Within a seventh preset duration, obtain the absolute value of the fifth difference between the SoE value of some cells in the battery pack and the cluster SoE value, sort the absolute values of the fifth differences in descending order, and based on the sorting, obtain cells with a quantity less than a fifth preset quantity and whose absolute value of the fifth difference exceeds a preset SoE difference threshold. Discharge the cells with an SoE greater than the cluster SoE value, and discharge the cells with an SoE less than the cluster SoE value;

[0037] Within an eighth preset duration, obtain the absolute value of the sixth difference between the SoE value of the remaining cells in the battery pack and the cluster SoE value, sort the absolute values of the sixth differences in descending order, and based on the sorting, obtain cells with a quantity less than a sixth preset quantity and whose absolute value of the sixth difference exceeds a preset SoE difference threshold. Discharge the cells with an SoE greater than the cluster SoE value, and discharge the cells with an SoE less than the cluster SoE value.

[0038] Preferably, in an embodiment of the battery pack balancing method for an energy storage device of the present invention, it further includes: monitoring the abnormal state of the energy storage device, and stopping balancing when an open circuit occurs in the voltage acquisition line or a temperature rise fault occurs in the energy storage device.

[0039] The present invention also provides an energy storage device control system, including a memory and a processor; the memory is used to store a computer program; the processor is used to execute the computer program to implement the method.

[0040] Implementing the battery pack balancing method for an energy storage device and the energy storage device control system of the present invention has the following beneficial effects: it can improve the balancing efficiency and enhance the energy utilization rate of the energy storage system. Brief Description of the Drawings

[0041] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0042] Figure 1 is a flowchart of a program of an embodiment of a method for balancing a battery pack of an energy storage device according to the present invention;

[0043] Figure 2 is Figure 1 a flowchart of a program of step S2 in one embodiment of

[0044] Figure 3 is Figure 1 a flowchart of a program of another embodiment of step S2 in

[0045] Figure 4 is Figure 1 a flowchart of a program of one embodiment of step S3 in

[0046] Figure 5 is Figure 1 a flowchart of a program of another embodiment of step S3 in

[0047] Figure 6 is Figure 1 a flowchart of a program of still another embodiment of step S3 in

[0048] Figure 7 is Figure 1 a flowchart of a program of still another embodiment of step S3 in Detailed Embodiments

[0049] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the drawings.

[0050] As Figure 1 shown, an embodiment of a method for balancing a battery pack of an energy storage device according to the present invention is shown. In Figure 1 the embodiment of a method for balancing a battery pack of an energy storage device according to the present invention shown, the following steps are included: S1. When the energy storage device is operating, obtain the currently accumulated charging energy in the energy storage device, and determine the balancing condition of the energy storage device according to the currently accumulated charging energy; S2. Confirm the charge and discharge state and the cluster SoE value of the energy storage device to determine the balancing mode of the energy storage device according to the charge and discharge state and the cluster SoE value of the energy storage device; S3. Balance the battery pack in the energy storage device according to the balancing condition and the balancing mode of the energy storage device.

[0051] Based on step S1, when the energy storage device is in a normal working state, obtain the accumulated charging energy that the energy storage device has reached. Here, the accumulated charging energy of the energy storage device refers to the total electrical energy stored through the charging process from the start of use of the energy storage device to the current time point. It can be understood that the longer the energy storage device has been in operation, the greater the corresponding accumulated charging energy, and the greater the change in the performance of the energy storage device compared to when it was first used. Simply put, the performance state of the energy storage device can be judged based on the accumulated charging energy of the energy storage device, and the equalization conditions of the energy storage device can be set according to the judgment result. Based on different performance states of the energy storage device, the selected equalization conditions for the energy storage device will also vary. For example, according to the cumulative charge and the SoE calibration status, after each static SoE calibration, the accumulated charging energy is cleared. That is to say, the SoE after each calibration is very accurate, but after charging and discharging for a period of time, the more the accumulated charging energy, the greater the possible error. If the SoE has not been calibrated for a long time, there will be a cumulative error in the SoE, and the credibility of the current SoE value will decrease. At this time, the voltage parameter can be selected as the judgment condition for whether to start equalization. If the SoE has been calibrated, the SoE parameter is used as the condition for starting equalization, and the factor of SoH is considered, as shown in the formula SoE` = SoE X SoH. When a new battery pack is replaced in the energy storage device, the nominal energy of the battery cells with different lifetimes is different. Therefore, even if the voltage of the new battery cells is lower than that of the old battery cells, the SoE of the new battery cells may be higher, and instead of charging equalization, discharging equalization is required. Here, the SoE of the battery cell is the percentage of the remaining energy of the battery cell in the total energy of the battery cell, and the cluster SoE value of the battery pack is the percentage of the remaining energy of the battery pack in the remaining energy of the battery pack.

[0052] Based on step S2, judge the charge and discharge state of the energy storage device, obtain the cluster SoE of the battery pack in the energy storage device, and determine the applicable equalization mode for the current energy storage device according to the charge and discharge state and the cluster SoE of the energy storage device. In the extreme value equalization mode, since a single cell is selected for equalization in each equalization channel and equalization needs to be stopped for a period of time to re-collect the single cells for equalization. In the efficiency equalization mode, equalization is performed on some single cells in time periods, and there is no need to stop equalization, so the equalization efficiency is higher.

[0053] Based on step S3, after selecting the equalization conditions and equalization mode of the energy storage device, the battery pack in the energy storage device can be equalized according to the set equalization conditions and equalization mode.

[0054] In one embodiment, in step S1, the currently accumulated charging energy in the energy storage device is obtained, and the equalization condition of the energy storage device is determined according to the currently accumulated charging energy, including: S11. When the currently accumulated charging energy is greater than the first preset value, the voltage parameter corresponding to the energy storage device is used as the equalization condition of the energy storage device; S12. When the currently accumulated charging energy is less than or equal to the first preset value, the SoE parameter corresponding to the energy storage device is used as the equalization condition of the energy storage device.

[0055] Specifically, the threshold value of the accumulated charging energy of the energy storage device, which corresponds to the first preset value, is determined. When the currently accumulated charging energy of the energy storage device exceeds this threshold value, the equalization condition of the energy storage device needs to be switched. This threshold value can be obtained according to the nominal energy of the energy storage device. In one embodiment, this threshold value is set to m * nominal energy. Where m is a constant, usually greater than zero and less than 1. The nominal energy is the nominal voltage of the battery X the capacity of the single cell. For example, for a lithium iron phosphate battery cell with a capacity of 280 Ah, the nominal energy: 3.2 V X 280 A = 896 W. Different cell types have different nominal voltages and capacities. When the currently accumulated charging energy exceeds this threshold value, the voltage parameter of the energy storage device is used as the equalization condition of the energy storage device, that is, the energy storage device performs the equalization process according to the corresponding voltage parameter. If the currently accumulated charging energy does not exceed this threshold value, the SoE parameter of the energy storage device is used as the equalization condition, that is, the energy storage device performs the equalization process according to the corresponding SoE parameter.

[0056] In one embodiment, as Figure 2 shown, in step S2, the charge-discharge state of the energy storage device and the cluster SoE value are confirmed to determine the equalization mode of the energy storage device according to the charge-discharge state of the energy storage device and the cluster SoE value, including: S21A. When the energy storage device is in the charging state, the cluster SoE value corresponding to the energy storage device is judged; S22A. When the cluster SoE value is greater than or equal to the second preset value, the equalization mode of the energy storage device is set to the extreme value equalization mode; S23A. When the cluster SoE value is less than the second preset value, the equalization mode of the energy storage device is set to the efficiency equalization mode.

[0057] Specifically, when the energy storage device is in the charging state, the cluster SoE value of the energy storage device is obtained and judged. If the cluster SoE is greater than or equal to the second preset value, the energy storage device can be set to enter the extreme value equalization mode and the battery pack is equalized. Otherwise, the energy storage device can be directly set to enter the efficiency equalization mode and the battery pack is equalized. In one embodiment, the second preset value is set to 90%. In other embodiments, the second preset value can be other values.

[0058] In one embodiment, as Figure 3As shown, in step S2, confirm the charge and discharge state of the energy storage device and the cluster SoE value to determine the equalization mode of the energy storage device according to the charge and discharge state of the energy storage device and the cluster SoE value; including: S21B. When the energy storage device is in the discharge state, judge the cluster SoE value corresponding to the energy storage device; S22B. When the cluster SoE value is less than or equal to the third preset value, set the equalization mode of the energy storage device to the extreme value equalization mode; S23B. When the cluster SoE value is greater than the third preset value, set the equalization mode of the energy storage device to the efficiency equalization mode.

[0059] Specifically, when the energy storage device is in the discharge state, obtain the cluster SoE value of the energy storage device and make a judgment. If the cluster SoE is less than or equal to the third preset value, the energy storage device can be set to enter the extreme value equalization mode to facilitate the equalization of the battery pack. Otherwise, the energy storage device can be directly set to enter the efficiency equalization mode and the equalization of the battery pack can be carried out. In one embodiment, the third preset value is set to 10%. In other embodiments, the third preset value can be other values.

[0060] In one embodiment, as Figure 4 shown, in step S3, equalize the battery packs in the energy storage device according to the equalization conditions of the energy storage device and the equalization mode of the energy storage device; including: S31A. When the voltage parameter corresponding to the energy storage device is used as the equalization condition of the energy storage device and the equalization mode of the energy storage device is the extreme value equalization mode; the equalization process of the battery packs in the energy storage device includes: S32A. Obtain the absolute value of the first difference between the single-cell voltage and the average cell voltage of all the battery cells in the battery pack within the first preset duration, sort the absolute values of the first differences in descending order, and according to the sorting, obtain the battery cells with the number less than the first preset number and the absolute value of the first difference exceeding the preset single-cell voltage difference threshold value. Discharge the battery cells with a single-cell voltage greater than the average cell voltage and charge the battery cells with a single-cell voltage less than the average cell voltage, and stop the equalization within the second preset duration.

[0061] Specifically, when the energy storage device performs equalization in the extreme value equalization mode with the voltage parameter as the equalization condition, within each equalization cycle, first obtain the individual voltages of all the battery cells in the battery pack and the average cell voltage of the battery pack within the first preset duration, and obtain the absolute value of the difference between each individual voltage and the average cell voltage, resulting in a number of first absolute difference values. Sort all the first absolute difference values in ascending order, and based on the sorting, obtain the battery cells whose first absolute difference values exceed the preset individual voltage difference threshold. Considering the impact of the equalization process on the energy storage system, set the number of selected battery cells to be within a certain data range, that is, less than the first preset number. Briefly understood, if the number of battery cells whose first absolute difference values exceed the preset individual voltage difference threshold is large and exceeds the first preset number, then select no more than the first preset number of battery cells in descending order according to the sorting. Discharge the battery cells whose individual voltages are greater than the average cell voltage and charge the battery cells whose individual voltages are less than the average cell voltage. And stop equalization within the second preset duration of the equalization cycle. It can be understood that the sum of the first preset duration and the second preset duration constitutes the equalization cycle. Within each equalization cycle, first perform equalization (corresponding to the first preset duration), and then stop equalization (corresponding to the second preset duration) until the next equalization cycle. Among them, the equalization cycle can be set in advance, and there may be differences for different energy storage devices. The preset individual voltage difference threshold can also be set as needed. For example, for battery cells with a small capacity, the voltage difference may be 20 mV, and the actual difference is 2 Ah. However, for battery cells with a large capacity, the voltage difference is 20 mV, and the actual difference is 20 Ah. Therefore, the larger the capacity of the battery cell, the smaller the set voltage difference. In one embodiment, the first preset duration and the second preset duration can be equal.

[0062] In one embodiment, as Figure 5 shown, in step S3, equalize the battery pack in the energy storage device according to the equalization condition of the energy storage device and the equalization mode of the energy storage device; including: S31B. When the SoE parameter corresponding to the energy storage device is used as the equalization condition of the energy storage device and the equalization mode of the energy storage device is the extreme value equalization mode; the equalization process of the battery pack in the energy storage device includes: S32B. Obtain the second absolute difference value between the SoE values of all the battery cells in the battery pack and the cluster SoE value within the third preset duration, and sort the second absolute difference values in ascending order. Based on the sorting, obtain the battery cells whose number is less than the second preset number and whose second absolute difference values exceed the preset SoE difference threshold. Discharge the battery cells whose SoE is greater than the cluster SoE value and charge the battery cells whose SoE is less than the cluster SoE value, and stop equalization within the fourth duration.

[0063] Specifically, when the energy storage device performs equalization in the extreme value equalization mode with the SoE parameter as the equalization condition, within each equalization cycle, first obtain the SoE values of all the battery cells in the battery pack and the cluster SoE value corresponding to the battery pack within the third preset duration, and obtain the absolute value of the difference between each SoE value and the cluster SoE value, resulting in a number of second absolute difference values. Sort all the second absolute difference values in ascending order, and based on the sorting, obtain the battery cells whose second absolute difference value exceeds the preset SoE difference threshold value. Considering the impact of the equalization process on the energy storage system, set the number of selected battery cells to be within a certain data range, that is, less than the second preset number. Briefly understood, if the number of battery cells whose second absolute difference value exceeds the preset SoE difference threshold value is large and exceeds the second preset number, then select no more than the second preset number of battery cells in descending order according to the sorting. Discharge the battery cells whose SoE value is greater than the cluster SoE value among them, and charge the battery cells whose SoE value is less than the cluster SoE value among them. And stop the equalization within the fourth preset duration of the equalization cycle. It can be understood that the sum of the third preset duration and the fourth preset duration constitutes the equalization cycle. Within each equalization cycle, first perform equalization (corresponding to the third preset duration), and then stop equalization (corresponding to the fourth preset duration) until the next equalization cycle. Among them, the equalization cycle can be set in advance, and there may be differences for different energy storage devices. The preset SoE difference threshold value can also be set as needed. The equalization cycle may be set according to different battery cell types. If the battery cell capacity is relatively small and the voltage changes rapidly, the set cycle may need to be shorter to improve the acquisition and update time. Because the individual voltage is not collected during the equalization time. In one embodiment, the third preset duration and the fourth preset duration may be equal.

[0064] In one embodiment, such as Figure 6As shown, in step S3, the battery packs in the energy storage device are balanced according to the balancing conditions of the energy storage device and the balancing mode of the energy storage device; including: S31C. When the voltage parameter corresponding to the energy storage device is used as the balancing condition of the energy storage device and the balancing mode of the energy storage device is the efficiency balancing mode; the balancing process of the battery packs in the energy storage device includes: S32C. Obtain the absolute value of the third difference between the single-cell voltage and the average cell voltage of some cells in the battery pack within the fifth preset time period, sort the absolute values of the third differences in descending order, and obtain the cells with the absolute value of the third difference exceeding the preset single-cell voltage difference threshold and less than the third preset quantity according to the sorting. Discharge the cells with a single-cell voltage greater than the average cell voltage and charge the cells with a single-cell voltage less than the average cell voltage; S33C. Obtain the absolute value of the fourth difference between the single-cell voltage and the average cell voltage of the remaining cells in the battery pack within the sixth preset time period, sort the absolute values of the fourth differences in descending order, and obtain the cells with the absolute value of the fourth difference exceeding the preset single-cell voltage difference threshold and less than the fourth preset quantity according to the sorting. Discharge the cells with a single-cell voltage greater than the average cell voltage and charge the cells with a single-cell voltage less than the average cell voltage.

[0065] Specifically, when the energy storage device uses the voltage parameter as the balancing condition and the efficiency balancing mode for balancing, within each balancing cycle, first obtain the single-cell voltage of some cells in the battery pack and the average cell voltage of the battery pack within the fifth preset time period, obtain the absolute value of the difference between each single-cell voltage and the average cell voltage, and obtain a number of absolute values of the third differences. Sort all the absolute values of the third differences in descending order, and obtain the cells with the absolute value of the third difference exceeding the preset single-cell voltage difference threshold. Considering the impact of the balancing process on the energy storage system, the number of selected cells is set to be within a certain data range, that is, less than the third preset quantity. Simply put, if the number of cells with the absolute value of the third difference exceeding the preset single-cell voltage difference threshold is large and exceeds the third preset quantity, then select no more than the third preset quantity of cells in descending order according to the sorting. Discharge the cells with a single-cell voltage greater than the average cell voltage and charge the cells with a single-cell voltage less than the average cell voltage.

[0066] Then, within the sixth preset duration of the equalization period, obtain the individual voltages of the remaining cells in the battery pack and the average cell voltage of the battery pack. Obtain the absolute value of the difference between each individual voltage and the average cell voltage to obtain a number of fourth absolute differences. Sort all the fourth absolute differences in ascending order, and based on the sorting, obtain the cells whose fourth absolute differences exceed the preset individual voltage difference threshold. Considering the impact of the equalization process on the energy storage system, set the number of selected cells to be within a certain data range, that is, less than the fourth preset number. Briefly understood, if the number of cells whose fourth absolute differences exceed the preset individual voltage difference threshold is large and exceeds the fourth preset number, then select no more than the fourth preset number of cells in descending order according to the sorting. Discharge the cells whose individual voltages are greater than the average cell voltage and charge the cells whose individual voltages are less than the average cell voltage.

[0067] It can be understood that the fifth preset duration and the sixth preset duration together constitute the equalization period. Within each equalization period, first perform the equalization of some cells (corresponding to the fifth preset duration), and then perform the equalization of the remaining cells (corresponding to the sixth preset duration). After that, enter the next equalization period. The equalization period can be set in advance, and there may be differences for different energy storage devices. The preset individual voltage difference threshold can also be set as needed. For example, for cells with a small cell capacity, the voltage difference may be 20 mV, and the actual difference is 2 Ah. However, for cells with a large cell capacity, the voltage difference is 20 mV, and the actual difference is 20 Ah. Therefore, the larger the cell capacity, the smaller the set voltage difference. In one embodiment, the fifth preset duration and the sixth preset duration can be equal. In another embodiment, the number of cells participating in the equalization process within the fifth preset duration and the sixth preset duration is equal. That is, within the fifth preset duration, obtain the individual voltages of half of the cells in the battery pack, and within the sixth preset duration, obtain the individual voltages of the other half of the cells in the battery pack.

[0068] In one embodiment, such as Figure 7As shown, in step S3, the battery packs in the energy storage device are balanced according to the balancing conditions of the energy storage device and the balancing mode of the energy storage device; including: S31D. When the SoE parameter corresponding to the energy storage device is used as the balancing condition of the energy storage device and the balancing mode of the energy storage device is the efficiency balancing mode; the balancing process of the battery packs in the energy storage device includes: S32D. Obtain the absolute value of the fifth difference between the SoE values of some battery cells in the battery pack and the cluster SoE value within the seventh preset time period, and sort the absolute values of the fifth difference in descending order. According to the sorting, obtain the battery cells with the absolute value of the fifth difference exceeding the preset SoE difference threshold and less than the fifth preset quantity, discharge the battery cells with SoE greater than the cluster SoE value, and charge the battery cells with SoE less than the cluster SoE value; S32D. Obtain the absolute value of the sixth difference between the SoE values of the remaining battery cells in the battery pack and the cluster SoE value within the eighth preset time period, and sort the absolute values of the sixth difference in descending order. According to the sorting, obtain the battery cells with the absolute value of the sixth difference exceeding the preset SoE difference threshold and less than the sixth preset quantity, discharge the battery cells with SoE greater than the cluster SoE value, and charge the battery cells with SoE less than the cluster SoE value.

[0069] Specifically, when the energy storage device uses the SoE parameter as the balancing condition and the efficiency balancing mode for balancing, within each balancing cycle, first obtain the SoE values of some battery cells in the battery pack and the cluster SoE value of the battery pack within the seventh preset time period, obtain the absolute value of the difference between each SoE value and the cluster SoE value, and obtain a number of absolute values of the fifth difference. Sort all the absolute values of the fifth difference in descending order. According to the sorting, obtain the battery cells with the absolute value of the fifth difference exceeding the preset SoE difference threshold. Considering the impact of the balancing process on the energy storage system, set the number of selected battery cells to be within a certain data range, that is, less than the fifth preset quantity. Simply put, if the number of battery cells with the absolute value of the fifth difference exceeding the preset SoE difference threshold is large and exceeds the fifth preset quantity, then select no more than the fifth preset quantity of battery cells from largest to smallest according to the sorting. Discharge the battery cells with SoE greater than the cluster SoE value and charge the battery cells with SoE less than the cluster SoE value.

[0070] Then, within the eighth preset duration of the equalization period, obtain the SoE values of the remaining cells in the battery pack and the cluster SoE value of the battery pack. Obtain the absolute value of the difference between each SoE value and the cluster SoE value to get a number of sixth absolute difference values. Sort all the sixth absolute difference values in ascending order, and based on the sorting, obtain the cells whose sixth absolute difference value exceeds the preset SoE difference threshold value. Considering the impact of the equalization process on the energy storage system, set the number of selected cells to be within a certain data range, that is, less than the sixth preset number. Briefly understood, if the number of cells whose sixth absolute difference value exceeds the preset SoE difference threshold value is large and exceeds the sixth preset number, then select no more than the sixth preset number of cells from largest to smallest according to the sorting. Discharge the cells whose SoE value is greater than the cluster SoE value among them, and charge the cells whose SoE value is less than the cluster SoE value among them.

[0071] It can be understood that the seventh preset duration and the eighth preset duration together constitute the equalization period. Within each equalization period, perform the equalization of some cells (corresponding to the seventh preset duration), and then perform the equalization of the remaining cells (corresponding to the eighth preset duration). After that, enter the next equalization period. Among them, the equalization period can be set in advance, and there may be differences for different energy storage devices. The preset SoE difference threshold value can also be set as needed, according to different cell types or application scenarios. For example, for a home energy storage project with a relatively small system capacity, the SoE difference may be slightly larger, not too large. For a large energy storage project, the SoE difference is smaller, because a small difference in the whole power station will result in a large difference in energy. In one embodiment, the seventh preset duration and the eighth preset duration can be equal. In another embodiment, the number of cells participating in the equalization process within the seventh preset duration and the eighth preset duration is equal, that is, within the seventh preset duration, obtain the SoE values of half of the cells in the battery pack, and within the sixth preset duration, obtain the SoE values of the other half of the cells in the battery pack.

[0072] In one embodiment, in the battery pack equalization method of the energy storage device of the present invention, it further includes: monitoring the abnormal state of the energy storage device, and stopping the equalization when an open circuit of the voltage acquisition line or a temperature rise fault occurs in the energy storage device. That is, in the present invention, only judge whether an open circuit of the voltage acquisition line or a temperature rise fault occurs in the energy storage device, that is, only consider the faults related to the accuracy of the collected single-cell voltage during the equalization process. Considering that an open circuit of the voltage acquisition line will cause inaccurate maximum and minimum single-cell voltage values collected. If the temperature rise rate is too fast, there may be situations such as poor soldering, and the temperature will rise rapidly during the charge and discharge process, resulting in inaccurate voltage acquisition. Therefore, when any one of the above two faults occurs in the energy storage device, stop the equalization. It is not necessary to stop the equalization when all primary faults occur.

[0073] In addition, a control system for an energy storage device according to the present invention has the function of implementing the corresponding steps performed in the above method. Each of these functions can be implemented by hardware or by hardware executing corresponding software. The corresponding hardware or software includes one or more modules corresponding to the above functions. That is, the steps in the above method are respectively executed by one or more modules. The specific cooperation operations between the modules can refer to the specific process of the above method and will not be elaborated here.

[0074] In addition, a control system for an energy storage device according to the present invention may further include a memory and a processor; the memory is used to store a computer program; the processor is used to execute the computer program to implement the above method. Specifically, according to an embodiment of the present invention, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present invention includes a computer program product that includes a computer program carried on a computer-readable medium, and the computer program includes program codes for executing the method shown in the flowchart. In such an embodiment, when the computer program is downloaded and installed by the energy storage device control system and executed, it executes the above functions defined in the method of the embodiment of the present invention.

[0075] It can be understood that the above embodiments only represent the preferred embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be construed as a limitation on the scope of the patent of the present invention; it should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can also be made, and these all belong to the protection scope of the present invention; therefore, all equivalent transformations and modifications made to the scope of the claims of the present invention should fall within the scope covered by the claims of the present invention.

Claims

1. A method for balancing a battery pack of an energy storage device, characterized in that: include: When the energy storage device is working, obtaining the current accumulated charging energy in the energy storage device, and determining the equilibrium condition of the energy storage device according to the current accumulated charging energy; Confirming the charge and discharge state and the cluster SoE value of the energy storage device to determine the balancing mode of the energy storage device according to the charge and discharge state and the cluster SoE value of the energy storage device; The battery pack in the energy storage device is balanced according to the balancing condition of the energy storage device and the balancing mode of the energy storage device.

2. The energy storage device battery pack balancing method according to claim 1, characterized in that: The step of obtaining the current accumulated charging energy in the energy storage device and determining the equilibrium condition of the energy storage device according to the current accumulated charging energy comprises: When the current accumulated charging energy is greater than a first preset value, a voltage parameter corresponding to the energy storage device is used as a balance condition of the energy storage device; When the current accumulated charging energy is less than or equal to the first preset value, the SoE parameter corresponding to the energy storage device is used as the balancing condition of the energy storage device.

3. The energy storage device battery pack balancing method according to claim 2, characterized in that: The step of confirming the charge and discharge state and the cluster SoE value of the energy storage device to determine the balancing mode of the energy storage device according to the charge and discharge state and the cluster SoE value of the energy storage device comprises: When the energy storage device is in a charging state, determining a cluster SoE value corresponding to the energy storage device; When the cluster SoE value is greater than or equal to a second preset value, setting the balancing mode of the energy storage device to an extreme value balancing mode; When the cluster SoE value is less than the second preset value, the balancing mode of the energy storage device is set to an efficiency balancing mode.

4. The energy storage device battery pack balancing method according to claim 2, characterized in that: The step of confirming the charge and discharge state and the cluster SoE value of the energy storage device to determine the balancing mode of the energy storage device according to the charge and discharge state and the cluster SoE value of the energy storage device comprises: When the energy storage device is in a discharging state, determining a cluster SoE value corresponding to the energy storage device; When the cluster SoE value is less than or equal to a third preset value, setting the balancing mode of the energy storage device to an extreme value balancing mode; When the cluster SoE value is greater than the third preset value, the balancing mode of the energy storage device is set to an efficiency balancing mode.

5. The energy storage device battery pack balancing method according to claim 3 or 4, characterized in that: The method of balancing the battery pack in the energy storage device according to the balancing condition of the energy storage device and the balancing mode of the energy storage device comprises: When the voltage parameter corresponding to the energy storage device is used as the balancing condition of the energy storage device, and the balancing mode of the energy storage device is the extreme value balancing mode; The balancing process of the battery pack in the energy storage device includes: Within a first preset time period, a first absolute value of a difference between a single cell voltage and an average cell voltage of all the battery cells in the battery pack is obtained, and the first absolute values ​​of the difference are sorted in order of size; based on the sorting, battery cells whose number is less than a first preset number and whose absolute values ​​of the first difference exceed a preset single cell voltage difference threshold are obtained; battery cells whose single cell voltage is greater than the average cell voltage are discharged, and battery cells whose single cell voltage is less than the average cell voltage are charged, and balancing is stopped within a second preset time period.

6. The energy storage device battery pack balancing method according to claim 3 or 4, characterized in that: The method of balancing the battery pack in the energy storage device according to the balancing condition of the energy storage device and the balancing mode of the energy storage device comprises: When the SoE parameter corresponding to the energy storage device is used as the balancing condition of the energy storage device, and the balancing mode of the energy storage device is the extreme value balancing mode; The balancing process of the battery pack in the energy storage device includes: Within a third preset time period, a second absolute value of the difference between the SoE values ​​of all the battery cells in the battery pack and the cluster SoE value is obtained, and the second absolute value of the difference is sorted in order of size, and battery cells less than a second preset number and whose second absolute value of the difference exceeds a preset SoE difference threshold are obtained according to the sorting, and the battery cells whose SoE is greater than the cluster SoE value are discharged, and the battery cells whose SoE is less than the cluster SoE value are discharged, and balancing is stopped within a fourth time period.

7. The energy storage device battery pack balancing method according to claim 3 or 4, characterized in that: The method of balancing the battery pack in the energy storage device according to the balancing condition of the energy storage device and the balancing mode of the energy storage device comprises: When the voltage parameter corresponding to the energy storage device is used as the balancing condition of the energy storage device, and the balancing mode of the energy storage device is the efficiency balancing mode; The balancing process of the battery pack in the energy storage device includes: Obtaining a third absolute value of a difference between a single cell voltage and an average cell voltage in some of the cells in the battery pack within a fifth preset time period, and sorting the third absolute values ​​of the difference in order of magnitude, obtaining cells less than a third preset number and whose third absolute values ​​of the difference exceed a preset single cell voltage difference threshold value according to the sorting, discharging cells whose single cell voltage is greater than the average cell voltage, and charging cells whose single cell voltage is less than the average cell voltage; Within a sixth preset time period, the fourth absolute value of the difference between the single cell voltage and the average cell voltage in the remaining battery cells in the battery pack is obtained, and the fourth absolute value of the difference is sorted in order of size. According to the sorting, battery cells whose number is less than the fourth preset number and whose fourth absolute value of the difference exceeds the preset single cell voltage difference threshold are obtained, and the battery cells whose single cell voltage is greater than the average cell voltage are discharged, and the battery cells whose single cell voltage is less than the average cell voltage are charged.

8. The energy storage device battery pack balancing method according to claim 3 or 4, characterized in that: The method of balancing the battery pack in the energy storage device according to the balancing condition of the energy storage device and the balancing mode of the energy storage device comprises: When the SoE parameter corresponding to the energy storage device is used as the balancing condition of the energy storage device, and the balancing mode of the energy storage device is the efficiency balancing mode; The balancing process of the battery pack in the energy storage device includes: within a seventh preset time period, obtaining a fifth absolute value of a difference between the SoE values ​​of some of the battery cells in the battery pack and the cluster SoE value, and sorting the fifth absolute values ​​of the difference in order of magnitude, obtaining battery cells less than a fifth preset number and whose fifth absolute values ​​of the difference exceed a preset SoE difference threshold value according to the sorting, discharging the battery cells whose SoE is greater than the cluster SoE value, and discharging the battery cells whose SoE is less than the cluster SoE value; Within an eighth preset time period, a sixth absolute value of the difference between the SoE values ​​of the remaining battery cells in the battery pack and the cluster SoE value is obtained, and the sixth absolute value of the difference is sorted in order of size. According to the sorting, battery cells whose number is less than the sixth preset number and whose sixth absolute value of the difference exceeds a preset SoE difference threshold are obtained, and battery cells whose SoE is greater than the cluster SoE value are discharged, and battery cells whose SoE is less than the cluster SoE value are discharged.

9. The energy storage device battery pack balancing method according to claim 1, characterized in that: The method further comprises: The abnormal state of the energy storage device is monitored, and when an open circuit or a temperature rise fault occurs in the voltage collection line of the energy storage device, balancing is stopped.

10. An energy storage device control system, characterized in that: including memory and processor; The memory is used to store computer programs; The processor is configured to execute the computer program to implement the method according to any one of claims 1 to 9.

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