CN117895626B - Control method and control system for cell balance in energy storage system - Google Patents

Abstract

The application provides a control method and a control system for cell balance in an energy storage system, which are used for improving the charge and discharge voltages and the uniformity of charge and discharge electric quantity of a plurality of cells. The control method for cell equalization comprises the following steps: recording charging/discharging data of a plurality of battery cells; screening out the battery cells to be balanced, which need to be balanced; after the charge/discharge is completed, the battery cells to be balanced are subjected to power compensation or discharge; the cell to be balanced comprises a high cell to be balanced and a low cell to be balanced. The screening step comprises the steps of determining a low battery cell to be balanced at the discharge end, and executing a compensation control strategy on the low battery cell to be balanced after the next charge; and determining a high cell to be balanced at the charging end, and executing a discharge control strategy on the high cell to be balanced after the next discharge.

Description

Control method and control system for cell balance in energy storage system

Technical Field

The application relates to the technical field of energy storage, in particular to a control method and a control system for cell balance in an energy storage system.

Background

The energy storage system is capable of regulating the balance between energy production and consumption to ensure efficient use and stable supply of energy. The energy storage system can store energy on different time and space scales to adapt to the change of the demand, thereby improving the economy and reliability of the whole energy system.

The main functions of the energy storage system include: peak clipping and valley filling and improving the self-utilization rate of new energy. Specifically, (1) the energy storage system may help balance power demand and supply, reduce peak grid load pressures, and store electrical energy for later use when demand is low. (2) The energy storage system is beneficial to smoothing the output power of new energy sources (such as wind energy and solar energy), and improving the controllability and the stability of the new energy sources, so that the proportion of the new energy sources in the total energy supply is improved. In order to ensure that the energy storage system better realizes two main functions of peak clipping and valley filling and improving the self-utilization rate of new energy, the battery cells in the energy storage system need to be controlled in a more stable and balanced manner.

The energy storage system is generally formed by connecting a plurality of electric cores (for example, lithium iron phosphate electric cores) in series and parallel, and the larger the electric quantity is, the more the electric cores are needed. In general, part of the electric quantity is converted into heat energy in the charge and discharge processes of the battery cell. The heat generated by different cells in the charge and discharge process is different due to the difference of internal resistances of the cells, the difference of connection materials of the cells in groups, the difference of assembly process, the difference of positions of the cells in the module, and the like. Therefore, after the battery system is used for a long time, the voltage difference between the battery cores can be gradually increased, and the available energy of the battery system is reduced due to the wooden barrel effect, so that the storage electric quantity of the energy storage system is reduced, and further the storage electric quantity of the energy storage power station is greatly reduced.

The inventors found that: the key of the cell balance control is to find a target cell and formulate an accurate balance strategy. (1) When a target battery cell is searched, the problem of misjudgment exists; (2) The equalization strategy is interfered by factors such as external environment, so that the conditions of excessive equalization, insufficient equalization and the like are easy to occur, the equalization effect is not easy to control, and the battery cells cannot be equalized accurately.

Disclosure of Invention

In view of the above, the application provides a control method and a control system for cell balancing in an energy storage system capable of accurately balancing cells.

The technical scheme provided by the application is as follows:

the control method is applied to the energy storage system comprising a plurality of electric cores and is used for improving the charge and discharge voltage among the electric cores and the uniformity of charge and discharge electric quantity;

s1, in the charging and discharging process of the energy storage system, recording charging/discharging data of a plurality of battery cells, wherein primary battery cell charging and primary battery cell discharging are a charging and discharging process;

S2, screening out to-be-balanced electric cores needing to be balanced, wherein the to-be-balanced electric cores comprise to-be-balanced high electric cores and to-be-balanced low electric cores, the to-be-balanced high electric cores need to execute a discharge control strategy to realize the balance of a plurality of electric cores, the to-be-balanced low electric cores need to execute a compensation control strategy to realize the balance of a plurality of electric cores, and the number of the to-be-balanced low electric cores and the number of the to-be-balanced high electric cores are natural numbers;

S3, after one-time charging or discharging of the energy storage system is completed, performing a compensation control strategy or a discharge control strategy on the battery cells to be balanced;

The step S2 of screening out the battery cells to be balanced which need to be balanced, and the step S3 of performing a compensation control strategy or a discharge control strategy on the battery cells to be balanced comprise the following steps:

determining the low battery cell to be balanced at the discharge end, and executing a compensation control strategy on the low battery cell to be balanced after the next charge;

And determining the high-voltage battery cell to be balanced at the charging end, and executing a discharge control strategy on the high-voltage battery cell to be balanced after the next discharge.

Further, the control method for cell balance in the energy storage system further comprises the step of detecting abnormal cells:

Determining the low battery cell to be balanced at the discharge end of the first charge-discharge process, and determining the high battery cell to be balanced at the charge end of the first charge-discharge process;

Judging whether the low battery cell to be balanced and the high battery cell to be balanced exist or not as the same battery cell;

if yes, the battery cell is an abnormal battery cell; if not, executing a compensation control strategy on the low-voltage battery cell to be balanced at the charging end in the second charging and discharging process, and executing a discharge control strategy on the high-voltage battery cell to be balanced at the discharging end in the second charging and discharging process.

Further, the step of determining the low cell to be balanced at the discharge end includes:

s10, acquiring discharge voltages of a plurality of battery cells at the discharge end to form a discharge voltage data set;

S11, determining a discharge mode voltage from the discharge voltage data set through mode selection;

S12, calculating a difference value between the discharge voltage of each cell and the discharge mode voltage, and taking the absolute value of the difference value as a first voltage difference value;

and S13, if the first voltage difference value is larger than a first voltage threshold value, determining that the battery cell is the low battery cell to be balanced, and recording the physical node position of the low battery cell to be balanced.

Further, the step of executing a compensation control strategy for the low battery cell to be balanced after the next charging includes:

S20, matching a channel of an equalizer according to the physical node position of the low battery cell to be equalized, so that the equalizer only supplements power for the low battery cell to be equalized, and the battery state of other battery cells is not affected;

s21, determining the power compensation parameters of the low battery cell to be balanced, wherein the power compensation parameters comprise any one or more of an operation mode, a voltage value, a current value and a capacity value of the balancing instrument;

S22, operating the balancing instrument to complete the power compensation of the low battery cell to be balanced.

Further, the step of determining the high cell to be balanced at the charging end includes:

S110, acquiring charging voltages of a plurality of battery cells at the charging terminal to form a charging voltage data set;

s111, determining a charging mode voltage from the charging voltage data set through mode selection;

S112, calculating a difference value between each charging mode voltage and the charging voltage of the battery cell, and taking an absolute value of the difference value as a second voltage difference value;

and S113, if the second voltage difference value is larger than a second voltage threshold value, determining that the battery cell is the high battery cell to be balanced, and recording the physical node position of the high battery cell to be balanced.

Further, the step of executing a discharge control strategy on the high cell to be balanced after the next discharge includes:

s210, matching a channel of an equalizer according to the physical node position of the high battery cell to be equalized, so that the equalizer only discharges the high battery cell to be equalized and the battery state of other battery cells is not affected;

S211, determining discharge parameters of the high battery cell to be balanced, wherein the discharge parameters comprise any one or more of an operation mode, a voltage value, a current value and a capacity value of the balancing instrument;

And S212, operating the balancing instrument to finish discharging the high battery cell to be balanced.

Further, in the step of determining a discharge mode voltage from the discharge voltage data set through mode selection S11, or determining a charge mode voltage from the charge voltage data set through mode selection S111, the determination of the discharge mode voltage and the charge mode voltage includes the steps of:

In the charge and discharge control process of the plurality of battery cells, recording charge voltage data of the plurality of battery cells at the charge end and discharge voltage data of the plurality of battery cells at the discharge end;

respectively determining an alternative charging voltage and an alternative discharging voltage in the charging voltage data and the discharging voltage data through mode selection;

If the number of the alternative charging voltages and the alternative discharging voltages is 1, the alternative charging voltages and the alternative discharging voltages are respectively used as the charging mode voltage and the discharging mode voltage;

If the number of the alternative charging voltages and the number of the alternative discharging voltages are respectively larger than or equal to 2, taking an average value of a plurality of the alternative charging voltages as the charging mode voltage; and taking an average value of a plurality of the alternative discharge voltages as the discharge mode voltage.

Further, when the charge control strategy is executed on the low battery cell to be balanced after the next charge and when the discharge control strategy is executed on the high battery cell to be balanced after the next discharge, the charge cell capacity value and the discharge cell capacity value are obtained through calculation according to the voltage and capacity correspondence table of the battery cell.

Further, the control method for cell balance in the energy storage system further comprises the following steps:

after the next charge is carried out and the compensation control strategy is carried out on the low-voltage battery cell to be balanced, the charge and discharge activity data of the low-voltage battery cell to be balanced is further monitored; and

After the next discharging, executing a discharging control strategy on the high-voltage battery cell to be balanced, and further monitoring charging and discharging activity data of the high-voltage battery cell to be balanced;

if the charge and discharge data of the low battery cell to be balanced and the high battery cell to be balanced in the last 3 times are restored to the normal numerical range after the primary power supply or discharge control strategy, the battery cell balancing control for the low battery cell to be balanced and the high battery cell to be balanced is completed;

if the charge and discharge data of the low battery cell to be balanced and the high battery cell to be balanced after the first charge and discharge control strategy are recovered to the normal numerical range, but the 3rd charge and discharge data are degraded to the battery cell to be balanced, performing the second battery cell balancing control on the battery cell to be balanced, and if the battery cell after performing the second battery cell balancing control is still not recovered to the normal numerical range in the subsequent charge and discharge data, replacing the battery cell;

And if the charge and discharge data of the low battery cell to be balanced and the high battery cell to be balanced are not restored to the normal numerical range after the charge and discharge control strategies are carried out for one time, executing a second charge and discharge control strategy on the low battery cell to be balanced at the charging end, executing a second discharge control strategy on the high battery cell to be balanced at the discharging end, further monitoring the charge and discharge activity data of the high battery cell to be balanced and the high battery cell to be balanced after the second charge control strategy and the second discharge control strategy, and if the charge and discharge activity data of the high battery cell to be balanced and the high battery cell to be balanced are not restored to the normal numerical range after the second charge control strategy and the second discharge control strategy, replacing the high battery cell to be balanced and the high battery cell to be balanced.

The application also provides a control system for balancing the battery cells in the energy storage system, which is applied to the energy storage system comprising a plurality of battery cells and is used for improving the charge and discharge voltage among the battery cells and the uniformity of charge and discharge electric quantity; the control system for cell equalization in the energy storage system comprises:

The battery core data recording device is used for recording charging/discharging data of a plurality of battery cores in the operation process of the energy storage system;

the battery cell electricity-supplementing or discharging auxiliary device is used for supplementing or discharging electricity to the battery cell to be balanced after the energy storage system is charged/discharged, and the battery cell electricity-supplementing or discharging auxiliary device is connected with the battery cell to be balanced in the use process;

the battery cells to be balanced comprise high battery cells to be balanced and low battery cells to be balanced, and the quantity of the low battery cells to be balanced and the quantity of the high battery cells to be balanced are natural numbers;

the control system for cell equalization in the energy storage system further comprises:

and the control device is used for receiving the data of the cell data recording device, determining the low cell to be balanced at the discharge end, executing a compensation control strategy on the low cell to be balanced after the next charge, determining the high cell to be balanced at the charge end, and executing a discharge control strategy on the high cell to be balanced after the next discharge.

According to the scheme provided by the application, the control method for balancing the battery cells in the energy storage system can realize abnormal judgment and balancing control of a plurality of battery cells in one charge and discharge process, and the judgment standard is more reasonable and accurate, and the charge and discharge control strategy is more effectively set. Has the following beneficial effects:

1. the control method selects the high battery cell at the charging end and selects the low battery cell at the discharging end, so that the method for selecting the battery cell to be balanced is more scientific and effective, and misjudgment of the battery cell to be balanced is avoided.

2. According to the control method, the battery cells to be balanced can be found in different time periods, the battery cells to be balanced are divided into two different types of battery cells to be balanced, different balanced actions are carried out on the different types of battery cells to be balanced, and accurate balanced control can be achieved on multiple battery cells at the same time.

3. The physical node position of the battery cell to be balanced is accurately positioned by calculating the difference value of the charge/discharge voltage and the charge/discharge mode voltage of each battery cell, the positioning method is more accurate and effective, and the calculation method can avoid misjudgment of the battery cell to be balanced.

4. Different equalization actions are respectively carried out on different types of battery cores to be equalized, and further, when different equalization actions are carried out, different battery core capacity values are set to serve as references, so that on one hand, the battery cores to be equalized can be protected, and overcharge or overdischarge of the battery cores to be equalized can be avoided, and the service life of the battery cores is affected; on the other hand, the battery cells to be balanced have different levels to be balanced, and the balance is realized through a small amount of repeated power supply/discharge, so that the maximization of the whole electric quantity of the energy storage system can be ensured.

5. After the battery cell is balanced at the tail end of each charge and discharge and once, parameters such as the electric quantity and the state of the battery cell are observed and recorded, and the next action guidance can be timely given for the change of the battery cell to be balanced.

In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 (a) is a diagram illustrating a voltage capacity of a battery cell during a charging process according to an embodiment of the present application; FIG. 1 (b) is a graph of the voltage capacity of a battery cell during a discharging process according to one embodiment of the present application;

fig. 2 is a flow chart of a control method for cell balancing in an energy storage system according to an embodiment of the present application;

Fig. 3 is a schematic diagram illustrating a use process of a method for controlling cell balancing in an energy storage system according to an embodiment of the present application;

FIG. 4 is a graph showing voltage data of a cluster of cells at a discharge end and a charge end before cell equalization in an energy storage system according to an embodiment of the present application, wherein the graph shows abnormal cells with low charge and low discharge;

FIG. 5 is a flowchart illustrating a step of determining a low cell to be balanced at a discharge end according to an embodiment of the present application;

fig. 6 is a schematic flow chart of a control strategy for executing compensation on a low-voltage cell to be balanced after the next charging according to an embodiment of the present application;

FIG. 7 is a schematic diagram illustrating a discharge voltage monitoring for a certain time according to an embodiment of the present application;

FIG. 8 is a schematic diagram illustrating monitoring of a voltage difference (first voltage difference) of a discharge mode voltage according to an embodiment of the present application;

FIG. 9 is a graph showing voltage data of 416 cells at the end of a primary discharge prior to cell equalization in accordance with one embodiment of the present application;

FIG. 10 is a graph showing voltage data of 416 cells at the end of a primary discharge after cell equalization according to one embodiment of the present application;

FIG. 11 is a graph showing voltage data of 416 cells at the end of a charge before cell equalization according to one embodiment of the present application;

fig. 12 is voltage data of 416 cells at the end of a primary charge after cell equalization according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present application.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.

As can be seen from the charge process cell voltage capacity diagram shown in fig. 1 (a) and the discharge process cell voltage capacity diagram shown in fig. 1 (b): the battery cell has a plateau phase during charge and discharge. Specifically, when the battery cell is in the platform phase, the battery cell is charged, the capacity of the battery cell can be greatly increased, but the voltage of the battery cell is not greatly increased; or when the battery cell is in the platform phase, the battery cell is discharged, the capacity of the battery cell can be greatly reduced, but the voltage of the battery cell is not greatly reduced. The change of the charging voltage and the discharging voltage is less obvious in the platform period of charging and discharging the battery cell. The change of the charging voltage and the discharging voltage is obvious in the non-platform phase of the charging and discharging of the battery cell. Therefore, if the target cell is found according to the conventional voltage difference method (conventional method 1: dynamically monitoring whether the voltage change of the cell exceeds the preset value; conventional method 2: statically comparing the maximum value or the minimum value of the cell voltage), there are obviously many misjudgments.

Therefore, the application provides a control method for cell equalization in an energy storage system, which can accurately find a target cell (a cell to be equalized) and can form an effective equalization control strategy. In practical application, the capacity of the battery cell is not increased to 100% or decreased to 0% every charge and discharge. When the capacity of the battery core after the battery core is charged and discharged is in the range of (2%, 98%) or (5%, 95%), or the capacity of the battery core after the battery core is charged and discharged is in the platform period of the battery core charging and discharging, the voltage difference of the battery core is not large, but the charging speed of the high battery core is the fastest in the charging process of the battery core, and the voltage difference between the voltage of the high battery core and the voltage difference of the basic battery core is large, so that the battery core is easier to find; similarly, in the discharging process of the battery cell, the discharging speed of the low battery cell is fastest, and the voltage difference between the voltage of the low battery cell and the voltage of the basic battery cell is larger, so that the low battery cell is easier to find. Thus, a high cell is found/determined at the charge end and a low cell is found/determined at the discharge end. Here, a high cell may be understood as a high cell to be balanced in the subsequent embodiment, and a low cell may be understood as a low cell to be balanced in the subsequent embodiment.

The application provides a control method for cell balance in an energy storage system, which is applied to the energy storage system comprising a plurality of cells and is used for improving charge and discharge voltage among the cells and uniformity of charge and discharge electric quantity. The control method for balancing the battery cells in the energy storage system can realize abnormal judgment and balancing control of the battery cells in one charge and discharge process, and the judgment standard is more reasonable and accurate, and the charge and discharge control strategy is more effectively set.

Referring to fig. 2 and 3, fig. 2 is a flow chart illustrating a control method for cell balancing in an energy storage system according to an embodiment of the application. Fig. 3 is a schematic diagram illustrating a use process of a method for controlling cell balancing in an energy storage system according to an embodiment of the present application.

The battery cell in the energy storage system is a lithium iron phosphate battery cell. The control method for cell equalization comprises the following steps:

S1, in the operation process of the energy storage system, recording charging/discharging data of a plurality of battery cores. The charging data and the discharging data comprise parameters such as nominal voltage, nominal capacity, charging voltage, discharging voltage, maximum charging current, rated charging current, maximum discharging current, rated discharging current, charging temperature, discharging temperature and the like of the battery cell.

S2, screening out the battery cells to be balanced, which need to be balanced. The cell to be balanced comprises a high cell to be balanced and a low cell to be balanced. The high cells to be balanced need to execute a discharge control strategy to realize the balance of the multiple cells, and the low cells to be balanced need to execute a compensation control strategy to realize the balance of the multiple cells (the uniformity of charge and discharge voltage and charge and discharge electric quantity among the multiple cells). The quantity of the low battery cells to be balanced and the quantity of the high battery cells to be balanced in the energy storage system are natural numbers. Natural numbers refer to integers greater than zero and without fractional parts. Such as: 0.1, 2 3......n. N is the total number of all cells in the energy storage system, for example, 416 cells may be provided in the energy storage system.

And S3, after the energy storage system is charged or discharged, carrying out a compensation control strategy or a discharge control strategy on the battery cells to be balanced. And supplementing electricity to the battery cells to be balanced with lower battery cell capacity so as to enable the battery cells to reach the nominal capacity of the battery cells. And discharging, namely discharging the battery cells to be balanced with higher battery cell capacity so as to enable the battery cells to reach the nominal capacity of the battery cells. And finally, the uniformity of charge and discharge voltage and charge and discharge electric quantity among the multiple battery cells is realized.

The control method for cell balance in the energy storage system further comprises the following steps:

And determining the low battery cells to be balanced at the discharge end, and executing a compensation control strategy for the low battery cells to be balanced after the next charge. And determining the high-voltage battery cell to be balanced at the charging end, and executing a discharge control strategy on the high-voltage battery cell to be balanced after the next discharge. Specifically, the charging terminal and the discharging terminal refer to the instant when the electric quantity of the battery cell is full and the instant when the electric quantity of the battery cell is discharged respectively.

As shown in fig. 3, the 3 charging and discharging processes of the battery cells in the energy storage system are illustrated, in the 1 st charging and discharging process, the high battery cell to be balanced is determined at the charging end, and the low battery cell to be balanced is determined at the discharging end; and executing a compensation control strategy on the low-voltage battery cell to be balanced at the charging end in the 2 nd charging and discharging process, and executing a discharge control strategy on the high-voltage battery cell to be balanced at the discharging end in the 2 nd charging and discharging process. And in the 2 nd charge-discharge process, determining a high cell to be balanced at the charge end and determining a low cell to be balanced at the discharge end; and executing a compensation control strategy on the low-voltage battery cell to be balanced at the charging end in the 3 rd charging and discharging process, and executing a discharge control strategy on the high-voltage battery cell to be balanced at the discharging end in the 3 rd charging and discharging process.

In this embodiment, a high cell is selected at the charging end, a low cell is selected at the discharging end, and the method for selecting the cell to be balanced is more scientific and effective, so that misjudgment of the cell to be balanced is avoided. According to the control method for balancing the battery cells in the energy storage system, the battery cells to be balanced can be found in different time periods, the battery cells to be balanced are divided into two different types of battery cells to be balanced, different balanced actions are carried out on the different types of battery cells to be balanced, and accurate balanced control can be achieved on multiple battery cells at the same time.

In one embodiment, the method for controlling cell balancing in an energy storage system further comprises the step of detecting abnormal cells:

if the charge-discharge of the battery cell is a charge-discharge process, determining a low battery cell to be balanced at the discharge end of the first charge-discharge process, and determining a high battery cell to be balanced at the charge end of the first charge-discharge process;

Judging whether the low battery cell to be balanced and the high battery cell to be balanced determined in the previous step are the same battery cell or not; in this step, the number of the low cells to be balanced and the number of the high cells to be balanced may be one or more, and when the number of the low cells to be balanced and the number of the high cells to be balanced are multiple, it is necessary to compare and determine whether the low cells to be balanced and the high cells to be balanced exist in the same cell (i.e., the 259 th cell shown in fig. 4 is the abnormal cell with the charge level low).

If yes, the battery cell is an abnormal battery cell; if not, executing a compensation control strategy on the low-voltage battery cell to be balanced at the charging end in the second charging and discharging process, and executing a discharge control strategy on the high-voltage battery cell to be balanced at the discharging end in the second charging and discharging process.

In this embodiment, in the actual application process, if an abnormal battery cell is detected, the abnormal battery cell needs to be replaced. The abnormal battery cell comprises a charge-high-low abnormal battery cell detected by the embodiment, and also comprises a charge-low-high abnormal battery cell detected by other modes.

In one embodiment, referring to fig. 5, the step of determining a low cell to be balanced at the discharge end includes:

And S10, acquiring discharge voltages of a plurality of battery cells at the discharge end, and forming a discharge voltage data set as shown in the following table 1. The discharge voltage values of 10 cells at the discharge end of 2023, 11, 1 to 20, V1 to V10 are shown in table 1 as discharge voltage data sets. In this example, the discharge voltage values of 416 cells at the discharge end were collected in total, and only 10 cells of data were shown here for illustration.

S11, a discharge mode voltage (mode voltage as shown in table 2) is determined by mode selection from the discharge voltage data set. In this step, the discharge mode voltage is selected as a reference for comparing the discharge data, so that the discreteness of the voltage data in the discharge voltage data set can be fully represented.

S12, calculating the difference value between the discharge voltage and the discharge mode voltage of each cell, and taking the absolute value of the difference value as a first voltage difference value (shown in table 2).

And S13, if the first voltage difference value is larger than the first voltage threshold value, determining the battery cell as a low battery cell to be balanced, and recording the physical node position of the low battery cell to be balanced. In one embodiment, the first voltage threshold may be set to 200mV.

As shown in the following tables 1 and 2, the voltage values of each cell are checked and recorded at each discharge end (or each discharge end), the mode voltage is determined from a plurality of voltage values of one discharge end, the difference between the discharge voltage and the discharge mode voltage of each cell is calculated, the absolute value of the difference is used as the first voltage difference, the cell with the largest voltage difference (such as the last column of "voltage difference MAX cell" in table 2) can be counted each day (or each discharge end), according to the statistics data of "voltage difference MAX cell", which cell (the cell with the data of V9 in table) always deviates from the cell with the largest discharge mode voltage, and also the number of times of which cell or cells deviate from the charge mode voltage is the largest. The first voltage difference of the cell V9 is within 100mV at and before 11 months 10, the first voltage difference of the cell V9 is between more than 100mV and 200mV after 11 months 10 and before 11 months 14, and the first voltage difference of the cell V9 is more than 200mV after 11 months 14 and after 11 months 14. The first voltage difference for this cell at V9 was 225mV at the end of the discharge on day 11, 16. In one embodiment, it may be provided that the feedback is not triggered when the first voltage difference is not greater than 200mV. When the first voltage difference is greater than or equal to 200mv, triggering feedback, and cell equalization is needed. In another embodiment, the feedback may be triggered when the first voltage difference is greater than or equal to 150mV for M consecutive days, and cell balancing is required.

Table 1: cell operation data record discharge voltage data set (voltage: V)

Table 2: discharge mode voltage and first voltage difference (voltage: V)

In the above embodiment, the difference between the discharge voltage and the discharge mode voltage of each cell is calculated to accurately locate the physical node position of the cell to be balanced, the positioning method is more accurate and effective, and the calculation method can avoid misjudgment of the battery cells to be balanced.

In one embodiment, referring to fig. 6, the step of performing the complementary control strategy for the low cells to be balanced after the next charge includes:

And S20, matching the channel of the balancing instrument according to the physical node position of the low battery cell to be balanced, so that the balancing instrument only supplements power for the low battery cell to be balanced, and the battery state of other battery cells is not affected.

S21, determining the power compensation parameters of the low battery cell to be balanced, wherein the power compensation parameters comprise any one or more of an operation mode (particularly different operation modes capable of setting constant voltage, constant current and constant power), a voltage value, a current value and a capacity value of the balancing instrument. In one embodiment, the discharge mode voltage may be used as a power up target for the low cells to be balanced. In one embodiment, the nominal/nominal capacity value may be taken as the power up target value for the low cells to be balanced.

S22, operating the balancing instrument to complete the electricity compensation of the low battery cell to be balanced.

In this embodiment, the balancing action of the power supply is performed after the next charging for the low battery cell to be balanced, and the battery cell to be balanced can be accurately positioned when the power supply balancing action is performed. And setting the power compensation parameters of the low battery cells to be balanced according to the calculated first voltage difference value, so that the power compensation process is more accurate and intelligent.

In one embodiment, the energy storage system includes a plurality of battery packs (Pack), and the battery cells in the battery packs are connected in different sampling manners, and the battery cells are supplied with electricity in different manners. The specific (1) sampling line is a PVC type sampling line. The PVC sampling line can only bear 0.2A current and cannot bear more than 2.5A current, so that the cell equalization can only be unpacked and equalized. (2) the sampling lines are in a line pattern. The harness type sampling line can bear 2.5-5A current, and a fixed constant portable equalizer can be used.

In one embodiment, the step of determining the high cells to be balanced at the charging end comprises:

S110, acquiring charging voltages of a plurality of battery cells at the charging terminal to form a charging voltage data set (refer to table 1, wherein the charging voltage values in the table are different).

S111, the charging mode voltage is determined from the charging voltage data set through mode selection (referring to table 2, the total voltage values in the table are different, and the voltage difference MAX cells may be different). In the step, the charging mode voltage is selected as a comparison reference of charging data, so that the discreteness of the voltage data in the charging voltage data set can be fully represented.

And S112, calculating the difference value between each charging mode voltage and the charging voltage of the battery cell, and taking the absolute value of the difference value as a second voltage difference value.

And S113, if the second voltage difference value is larger than the second voltage threshold value, determining the battery cell as a high battery cell to be balanced, and recording the physical node position (physical node position, voltage) of the high battery cell to be balanced. In one embodiment, the second voltage threshold may be set to 200mV.

In this embodiment, the voltage value of each cell can be checked and recorded at the charging end (or at the charging end each time) every day, the mode voltage is determined from a plurality of voltage values of one charging end, the difference between the charging voltage of each cell and the charging mode voltage is calculated, the absolute value of the difference is used as the second voltage difference, the cell with the largest voltage difference (used as the "voltage difference MAX cell") can be counted every day (or at the charging end each time), and according to the statistics data of the "voltage difference MAX cell", it can be seen which cell has the voltage value at the charging end always being the cell with the largest deviation from the charging mode voltage, and also can be seen which cell or cells have the largest deviation from the charging mode voltage. In one embodiment, it may be provided that the feedback is not triggered when the second voltage difference is not greater than 200 mV. And when the second voltage difference is greater than or equal to 200mv, triggering feedback, and balancing the battery cells. In another embodiment, the feedback may be triggered when the second voltage difference is greater than or equal to 150mV for M consecutive days, and cell balancing is required. In the above embodiment, the difference between the charging voltage and the charging mode voltage of each cell is calculated to accurately locate the physical node position where the cell to be balanced is located, and the locating method is more accurate and effective, and the calculating method can avoid misjudgment of the cell to be balanced.

In one embodiment, the step of performing a discharge control strategy for the high cells to be balanced after the next discharge comprises:

and S210, matching the channel of the balancing instrument according to the physical node position of the high battery cell to be balanced, so that the balancing instrument only discharges the high battery cell to be balanced, and the battery state of other battery cells is not affected.

S211, determining a discharge parameter of the high battery cell to be balanced, wherein the discharge parameter comprises any one or more of an operation mode (particularly, different operation modes of constant voltage, constant current and constant power) of the balancing instrument, a voltage value, a current value and a capacity value. In one embodiment, the charge mode voltage may be used as the discharge target value for the high cells to be balanced. In one embodiment, the nominal/nominal capacity value may be taken as the power up target value for the high cells to be balanced.

And S212, operating the balancing instrument to finish discharging the high battery cells to be balanced.

In this embodiment, the equalization operation of discharging is performed after the next discharging for the high cell to be equalized, and the cell to be discharged can be accurately positioned when the discharge equalization operation is performed. And setting the discharge parameters of the high battery cells to be balanced according to the calculated second voltage difference value, so that the discharge process is more accurate and intelligent.

In one embodiment, S11, determining the discharge mode voltage from the discharge voltage dataset through mode selection, or S111, determining the charge mode voltage from the charge voltage dataset through mode selection, the determining of the discharge mode voltage and the charge mode voltage includes the steps of:

In the charge and discharge control process of the multiple electric cores, the charge voltage data of the multiple electric cores at the charge end and the discharge voltage data at the discharge end are recorded.

In the charge voltage data and the discharge voltage data, an alternative charge voltage and an alternative discharge voltage are determined by mode selection, respectively. The alternative charging voltage and the alternative discharging voltage may be charging voltage values and discharging voltage values with highest occurrence frequency obtained through statistics. The alternative charging voltages may be one or more. The alternative discharge voltage may be one or more.

If the number of the alternative charging voltages and the alternative discharging voltages is 1, the alternative charging voltages and the alternative discharging voltages are respectively the charging mode voltage and the discharging mode voltage.

And if the number of the alternative charging voltages and the number of the alternative discharging voltages are respectively greater than or equal to 2, taking the average value of the alternative charging voltages as the charging mode voltage. Similarly, the alternative discharge voltage is averaged as the discharge mode voltage.

Specifically, the voltage data for 1-10 of these 10 cells at the end of a charge is shown in the example shown in Table 3. The voltage data for 1-10 of these 10 cells at the end of a charge is shown in the example shown in table 4. The alternative charging voltage in table 3 has only one value, 3.119V, so this alternative charging voltage (3.119V) is the charging mode voltage 3.119V. The alternative charging voltages in table 4 have two values, 3.09V and 3.12V, respectively, and the average value of the two alternative charging voltages, 3.105V, is taken as the charging mode voltage.

Table 3: cell operation data recording-charging terminal voltage data

Table 4: cell operation data recording-charging terminal voltage data

In this embodiment, the mode of determining the mode voltage is further refined, so that the first voltage difference value and the second voltage difference value can be determined more accurately, and further, the accuracy of the cell to be balanced can be improved, so that the physical node position where the cell to be balanced is located can be positioned more accurately, the positioning method is more accurate and effective, and the misjudgment of the cell to be balanced can be avoided by the calculation method.

In another embodiment, the specific mode voltage calculation method may be implemented by a mode voltage calculation module, and the mode voltage calculation module may include the following steps:

(1) The CSV file is read, and a specific CSV file is composed of any number of records, and the records are separated by a certain line-feed symbol. Each record consists of fields, with the separators between the fields being other characters or strings, most commonly commas or tab.

(2) And finding out corresponding battery cell data in the CSV file, wherein the battery cell data comprise the serial number of the battery cell, the physical node position of the low battery cell, the charging voltage, the discharging voltage and other data.

(3) And calculating the numerical value of the cell data. Such as: a charge mode voltage and a discharge mode voltage.

(4) And calculating the difference value (first voltage difference value and/or second voltage difference value) between each cell and the mode, and when the difference value exceeds a standard value (first voltage threshold value and/or second voltage threshold value), determining that the cell is in an abnormal position, and recording the cell.

(5) The die data is patterned as shown in fig. 7 and 8. Fig. 7 is a monitor diagram of a discharge voltage, and fig. 8 is a monitor diagram of a voltage difference (first voltage difference) of a discharge mode voltage.

(6) And returning and displaying the serial numbers and the data of the abnormal cell. As shown in fig. 8, the mode voltage calculation module feeds back: v9 cell voltage: 2.895V, the difference in discharge mode voltage (first voltage difference): cell balancing is required for 0.225V, which exceeds the first voltage threshold by 200mV for 3 consecutive days.

In one embodiment, when the charge control strategy is executed on the low-voltage battery cell to be balanced after the next charge and when the discharge control strategy is executed on the high-voltage battery cell to be balanced after the next discharge, the charge battery cell capacity value and the discharge battery cell capacity value are obtained through calculation according to the voltage and capacity corresponding table of the battery cell. The voltage and capacity correspondence table of the specific battery cell can be provided by a battery cell manufacturer.

In the embodiment, the rationalized setting of the power supply and discharge strategies can protect the battery cells to be balanced on one hand and avoid overcharge or overdischarge of the battery cells, thereby influencing the service life of the battery cells; on the other hand, the battery cells to be balanced have different levels to be balanced, and the balance is realized through a small amount of repeated power supply/discharge, so that the maximization of the whole electric quantity of the energy storage system can be ensured.

In one embodiment, the method for controlling cell balancing in the energy storage system further comprises:

and after the next charge and the compensation control strategy is executed on the low-voltage battery cells to be balanced, further monitoring the charge and discharge activity data of the low-voltage battery cells to be balanced. And after the discharge control strategy is executed on the high battery cell to be balanced after the next discharge, further monitoring the charge and discharge activity data of the high battery cell to be balanced.

If the charge and discharge data of the low battery cell to be balanced and the high battery cell to be balanced in the last 3 times are restored to the normal numerical range after the primary power supply or discharge control strategy, the battery cell balancing control for the low battery cell to be balanced and the high battery cell to be balanced is completed. It will be appreciated that the normal value ranges herein are "the first voltage difference is less than or equal to the first voltage threshold", and/or "the second voltage difference is less than or equal to the second voltage threshold", and/or "the charging voltage of the plurality of cells at the charging end is 3.45V-3.65V", and/or "the discharging voltage of the plurality of cells at the discharging end is 2.8V-3.1V". The first voltage threshold and the second voltage threshold may be set to 100mV.

If the low-level cell to be balanced and the high-level cell to be balanced recover to the normal value range after the first charge-discharge control strategy is adopted, but the low-level cell to be balanced and the high-level cell to be balanced degrade to the cell to be balanced in the 3 rd charge-discharge data, the second-level cell balancing control is executed for the cell to be balanced, and if the cell after the second-level cell balancing control is executed still can not recover to the normal value range in the subsequent charge-discharge data, the cell is replaced.

And if the charge and discharge data of the low battery cell to be balanced and the high battery cell to be balanced are not restored to the normal numerical range after the first charge and discharge control strategy is adopted, executing a second charge and discharge control strategy on the low battery cell to be balanced at the charging end, executing a second discharge control strategy on the high battery cell to be balanced at the discharging end, further monitoring the charge and discharge activity data of the high battery cell to be balanced and the high battery cell to be balanced after the second charge control strategy and the second discharge control strategy, and if the charge and discharge activity data of the high battery cell to be balanced and the high battery cell to be balanced are not restored to the normal numerical range after the second charge control strategy and the second discharge control strategy, replacing the high battery cell to be balanced and the battery cell to be balanced.

In this embodiment, after each charge and discharge terminal and one equalization, parameters such as the electric quantity and the state of the battery cell are observed and recorded, and the next action guidance can be timely given to the change of the battery cell to be equalized. In addition, in the embodiment, different compensation control strategies are set according to different detection data, so that the service life of the battery cell is ensured to the maximum extent under reasonable data monitoring, and excessive elimination/excessive replacement of the battery cell is avoided.

In one embodiment, in the energy storage system, the charging voltage of the plurality of battery cells at the charging end is 3.45V-3.65V, the discharging voltage of the plurality of battery cells at the discharging end is 2.8V-3.1V, and the first voltage threshold and the second voltage threshold are both 100mV. In some embodiments, the first voltage threshold and the second voltage threshold may also be set to 150mV; in some embodiments, the first voltage threshold and the second voltage threshold may also be set to be 200mV.

In one embodiment, the battery cell charging voltage is set to reach 3.6V to trigger the charge-forbidden protection, the battery cell discharging voltage is set to reach 2.8V to trigger the charge-forbidden protection, and the battery cell voltage difference is set to reach 0.5V to trigger the charge-forbidden protection.

The application also provides a control system for balancing the battery cells in the energy storage system, which is applied to the energy storage system comprising a plurality of battery cells and is used for improving the charge and discharge voltage among the battery cells and the uniformity of charge and discharge electric quantity. A control system for cell equalization in an energy storage system, comprising: the system comprises a cell data recording device, a cell electricity supplementing or discharging auxiliary device and a control device.

And the battery core data recording device is used for recording the charging/discharging data of the battery cores in the operation process of the energy storage system.

And the battery cell electricity supplementing or discharging auxiliary device is used for supplementing or discharging the battery cell to be balanced after the energy storage system is charged or discharged, and is connected with the battery cell to be balanced in the use process.

The battery cells to be balanced comprise high battery cells to be balanced and low battery cells to be balanced, and the quantity of the low battery cells to be balanced and the quantity of the high battery cells to be balanced are natural numbers.

Control system of balanced battery cell in energy storage system still includes:

And the control device is used for receiving the data of the cell data recording device, determining the low cell to be balanced at the discharge end, executing a compensation control strategy for the low cell to be balanced after the next charge, determining the high cell to be balanced at the charge end, and executing a discharge control strategy for the high cell to be balanced after the next discharge.

The control system for cell balancing in the energy storage system according to the above embodiment may perform the control method for cell balancing in the energy storage system according to any of the above embodiments, and has the corresponding beneficial effects.

In one particular embodiment: in practical applications, the control system for cell balancing in the energy storage system may be incorporated in a BMS (battery management system). Before the battery cells are actively balanced, the running battery cells are monitored in real time, and then the battery cells needing to be balanced are found. Specifically, the logic of finding the cell to be balanced (including the high cell to be balanced and the low cell to be balanced) is that:

1. And (3) data acquisition:

Daily charge/discharge amount data is acquired from a BMS (battery management system), and the data are collected in chronological order (as shown in table 1, the data may be collected).

2. Data analysis:

Calculating the voltage difference between each cell voltage and the mode cell voltage (the discharge mode voltage or the charge mode voltage) every day;

The pressure differences were summarized in time series (the discharge mode voltages and the first voltage differences may be summarized as shown in table 2);

detecting whether the mode voltage difference of each cell tends to be large or whether the mode voltage difference exceeds a preset threshold value;

If the trend is larger or the preset threshold value is exceeded, information feedback is carried out.

3. And (3) data feedback:

summarizing information of cell mode voltage differences (such as the first voltage difference and/or the second voltage difference) occurring in the data analysis process;

Feedback is carried out on the voltage, mode voltage and differential pressure information of the battery cell which is close to the threshold value (the voltage is lower than/higher than an alarm value or the differential pressure reaches 200 mv);

the above information is further fed back to the BMS system in preparation for cell balancing.

In one embodiment, the energy storage system includes 416 cells in the 1 st cluster of cells. As shown in fig. 9-12, the voltage data of the charge and discharge of 416 cells in the 1 st cluster of cells are counted, and the charge and discharge control strategy is executed according to the steps shown in any of the embodiments, wherein the discharge end schematic diagram before cell equalization is shown in fig. 9, the discharge voltage of the 330 th cell at the discharge end is 3.081V, the discharge mode voltage is 3.189V, the first voltage difference is 0.108V (108 mV), and since the first voltage difference of the 330 th cell is 108mV > 100mV, the equalization is performed, and the power is supplied after the next charge.

The discharge end schematic diagram of the 330 th cell after equalization is shown in fig. 10, and fig. 10 shows that the voltage of the 330 th cell after the next discharge is 3.155V, the discharge mode voltage is 3.164V, and the first voltage difference is 0.009V (9 mV). As can be seen from the data in fig. 9 and 10, the first voltage difference of the 330 th cell before equalization is 108mV, and the first voltage difference after equalization is 9mV, so that the 330 th cell has completed cell equalization, and only the data of the charge and discharge ends of the 330 th cell need to be continuously monitored in the next charge and discharge process.

The schematic diagram of the charging end before cell equalization is shown in fig. 11, in which the charging voltage of the 330 th cell at the charging end is 3.445V, the charging mode voltage is 3.504V, and the second voltage difference is 0.059V (59 mV), so that it can be seen that the 330 th cell second voltage difference is 59mV, and although the second voltage threshold is not exceeded, the first voltage difference monitored in fig. 9 is already exceeded by the first voltage threshold, and therefore equalization is performed at the charging end of the second time (i.e. after the data acquisition in fig. 11, cell equalization is performed on the 330 th cell).

The schematic diagram of the charging end of the 330 th cell after equalization is shown in fig. 12, and fig. 12 shows that the voltage of the 330 th cell at the charging end is 3.399V, the charging mode voltage is 3.445V, and the second voltage difference is 0.046V (46 mV). As can be seen from the data in fig. 11 and fig. 12, the second voltage difference of the 330 th cell before equalization is 59mV, and the second voltage difference after equalization is 46mV, so that after the 330 th cell is charged at the charging end, the cell is equalized, and the cell performance of the 330 th cell is improved to a certain extent in both the charging process and the discharging process. After the equalization control is made for the 330 th cell, it can be seen from fig. 10 and 12: the charge and discharge voltages of the 330 th cell are respectively closer to the charge mode voltage and the discharge mode voltage, so that the cell balance control is successful.

More specifically, fig. 9 is voltage data of 416 cells at the primary discharge end before equalization, fig. 11 is voltage data of 416 cells at the primary charge end before equalization, and after fig. 11, power is supplemented, fig. 10 is voltage data of 416 cells at the primary discharge end after equalization, and it can be seen that the discharge voltage of the 330 th cell is already close to the discharge mode voltage. Fig. 12 shows the voltage data of the 416 cells at the end of primary charge after equalization, and it can be seen that the charging voltage of the 330 th cell is also closer to the charge mode voltage. By looking at the charge end data, it was found that 330 th cell reached the target value, but when the overall voltage of the cluster (cluster 1) was lower than before, there was a charged cell in the stack. Looking at the total charge of the battery stack on the same day, it can be seen that the total charge on the same day is obviously improved, and the electric quantity is increased by 254kW.h.

The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (8)

1. The control method is applied to the energy storage system comprising a plurality of electric cores and is used for improving the charge and discharge voltage among the electric cores and the uniformity of charge and discharge electric quantity;

it is characterized in that the method comprises the steps of,

S1, in the charging and discharging process of the energy storage system, recording charging/discharging data of a plurality of battery cells, wherein primary battery cell charging and primary battery cell discharging are a charging and discharging process;

S2, screening out to-be-balanced electric cores needing to be balanced, wherein the to-be-balanced electric cores comprise to-be-balanced high electric cores and to-be-balanced low electric cores, the to-be-balanced high electric cores need to execute a discharge control strategy to realize the balance of a plurality of electric cores, the to-be-balanced low electric cores need to execute a compensation control strategy to realize the balance of a plurality of electric cores, and the number of the to-be-balanced low electric cores and the number of the to-be-balanced high electric cores are natural numbers;

S3, after one-time charging or discharging of the energy storage system is completed, performing a compensation control strategy or a discharge control strategy on the battery cells to be balanced;

The step S2 of screening out the battery cells to be balanced which need to be balanced, and the step S3 of performing a compensation control strategy or a discharge control strategy on the battery cells to be balanced comprise the following steps:

determining the low battery cell to be balanced at the discharge end, and executing a compensation control strategy on the low battery cell to be balanced after the next charge;

Determining the high battery cell to be balanced at the charging end, and executing a discharge control strategy on the high battery cell to be balanced after the next discharge;

the step of determining the low cell to be balanced at the discharge end comprises the following steps:

s10, acquiring discharge voltages of a plurality of battery cells at the discharge end to form a discharge voltage data set;

S11, determining a discharge mode voltage from the discharge voltage data set through mode selection;

S12, calculating a difference value between the discharge voltage of each cell and the discharge mode voltage, and taking the absolute value of the difference value as a first voltage difference value;

S13, if the first voltage difference value is larger than a first voltage threshold value, determining that the battery cell is the low battery cell to be balanced, and recording the physical node position of the low battery cell to be balanced;

the step of determining the high battery cell to be balanced at the charging end comprises the following steps:

S110, acquiring charging voltages of a plurality of battery cells at the charging terminal to form a charging voltage data set;

s111, determining a charging mode voltage from the charging voltage data set through mode selection;

S112, calculating a difference value between each charging mode voltage and the charging voltage of the battery cell, and taking an absolute value of the difference value as a second voltage difference value;

and S113, if the second voltage difference value is larger than a second voltage threshold value, determining that the battery cell is the high battery cell to be balanced, and recording the physical node position of the high battery cell to be balanced.

2. The method for controlling cell balancing in an energy storage system of claim 1, further comprising the step of detecting abnormal cells:

Determining the low battery cell to be balanced at the discharge end of the first charge-discharge process, and determining the high battery cell to be balanced at the charge end of the first charge-discharge process;

Judging whether the low battery cell to be balanced and the high battery cell to be balanced exist or not as the same battery cell;

if yes, the battery cell is an abnormal battery cell; if not, executing a compensation control strategy on the low-voltage battery cell to be balanced at the charging end in the second charging and discharging process, and executing a discharge control strategy on the high-voltage battery cell to be balanced at the discharging end in the second charging and discharging process.

3. The method for controlling cell balancing in an energy storage system according to claim 2, wherein the step of performing a complementary control strategy on the low cell to be balanced after the next charging comprises:

S20, matching a channel of an equalizer according to the physical node position of the low battery cell to be equalized, so that the equalizer only supplements power for the low battery cell to be equalized, and the battery state of other battery cells is not affected;

s21, determining the power compensation parameters of the low battery cell to be balanced, wherein the power compensation parameters comprise any one or more of an operation mode, a voltage value, a current value and a capacity value of the balancing instrument;

S22, operating the balancing instrument to complete the power compensation of the low battery cell to be balanced.

4. The method of claim 3, wherein the step of performing a discharge control strategy for the high cells to be balanced after the next discharge comprises:

s210, matching a channel of an equalizer according to the physical node position of the high battery cell to be equalized, so that the equalizer only discharges the high battery cell to be equalized and the battery state of other battery cells is not affected;

S211, determining discharge parameters of the high battery cell to be balanced, wherein the discharge parameters comprise any one or more of an operation mode, a voltage value, a current value and a capacity value of the balancing instrument;

And S212, operating the balancing instrument to finish discharging the high battery cell to be balanced.

5. The method of claim 4, wherein S11, the step of determining a discharge mode voltage from the discharge voltage dataset by mode selection, or S111, the step of determining a charge mode voltage from the charge voltage dataset by mode selection, the determination of the discharge mode voltage and the charge mode voltage comprises the steps of:

In the charge and discharge control process of the plurality of battery cells, recording charge voltage data of the plurality of battery cells at the charge end and discharge voltage data of the plurality of battery cells at the discharge end;

respectively determining an alternative charging voltage and an alternative discharging voltage in the charging voltage data and the discharging voltage data through mode selection;

If the number of the alternative charging voltages and the alternative discharging voltages is 1, the alternative charging voltages and the alternative discharging voltages are respectively used as the charging mode voltage and the discharging mode voltage;

If the number of the alternative charging voltages and the number of the alternative discharging voltages are respectively larger than or equal to 2, taking an average value of a plurality of the alternative charging voltages as the charging mode voltage; and taking an average value of a plurality of the alternative discharge voltages as the discharge mode voltage.

6. The method according to claim 5, wherein the cell capacity value for the compensation and the cell capacity value for the discharge are calculated according to a voltage and capacity correspondence table of the cell when the compensation control strategy is performed on the low cell to be balanced after the next charge and when the discharge control strategy is performed on the high cell to be balanced after the next discharge.

7. The method of claim 6, further comprising:

after the next charge is carried out and the compensation control strategy is carried out on the low-voltage battery cell to be balanced, the charge and discharge activity data of the low-voltage battery cell to be balanced is further monitored; and

After the next discharging, executing a discharging control strategy on the high-voltage battery cell to be balanced, and further monitoring charging and discharging activity data of the high-voltage battery cell to be balanced;

if the charge and discharge data of the low battery cell to be balanced and the high battery cell to be balanced in the last 3 times are restored to the normal numerical range after the primary power supply or discharge control strategy, the battery cell balancing control for the low battery cell to be balanced and the high battery cell to be balanced is completed;

if the charge and discharge data of the low battery cell to be balanced and the high battery cell to be balanced after the first charge and discharge control strategy are recovered to the normal numerical range, but the 3rd charge and discharge data are degraded to the battery cell to be balanced, performing the second battery cell balancing control on the battery cell to be balanced, and if the battery cell after performing the second battery cell balancing control is still not recovered to the normal numerical range in the subsequent charge and discharge data, replacing the battery cell;

And if the charge and discharge data of the low battery cell to be balanced and the high battery cell to be balanced are not restored to the normal numerical range after the charge and discharge control strategies are carried out for one time, executing a second charge and discharge control strategy on the low battery cell to be balanced at the charging end, executing a second discharge control strategy on the high battery cell to be balanced at the discharging end, further monitoring the charge and discharge activity data of the high battery cell to be balanced and the high battery cell to be balanced after the second charge control strategy and the second discharge control strategy, and if the charge and discharge activity data of the high battery cell to be balanced and the high battery cell to be balanced are not restored to the normal numerical range after the second charge control strategy and the second discharge control strategy, replacing the high battery cell to be balanced and the high battery cell to be balanced.

8. The control system is applied to the energy storage system comprising a plurality of electric cores and is used for improving the charge and discharge voltage among the electric cores and the uniformity of charge and discharge electric quantity; the method for controlling cell balance in the energy storage system is characterized in that the control system for cell balance in the energy storage system is used for executing the control method for cell balance in the energy storage system according to any one of claims 1 to 7, and comprises the following steps:

The battery core data recording device is used for recording charging/discharging data of a plurality of battery cores in the operation process of the energy storage system;

the battery cell electricity-supplementing or discharging auxiliary device is used for supplementing or discharging electricity to the battery cell to be balanced after the energy storage system is charged/discharged, and the battery cell electricity-supplementing or discharging auxiliary device is connected with the battery cell to be balanced in the use process;

the battery cells to be balanced comprise high battery cells to be balanced and low battery cells to be balanced, and the quantity of the low battery cells to be balanced and the quantity of the high battery cells to be balanced are natural numbers;

the control system for cell equalization in the energy storage system further comprises:

and the control device is used for receiving the data of the cell data recording device, determining the low cell to be balanced at the discharge end, executing a compensation control strategy on the low cell to be balanced after the next charge, determining the high cell to be balanced at the charge end, and executing a discharge control strategy on the high cell to be balanced after the next discharge.