Energy storage system SOC balance control method, device, energy storage system and storage medium

Abstract

The present application discloses a SOC balancing control method, device, energy storage system and storage medium for an energy storage system, which relates to the field of energy storage technology, in order to at least solve the technical problem that the voltage-SOC curve based on the relevant technology cannot be flexibly adjusted according to the working condition application requirements, thereby resulting in poor SOC accuracy. The method includes: for any energy storage cabinet, determining a balancing control mode that matches the operating condition of the energy storage cabinet from multiple balancing control models; when in the first unilateral balancing control mode, determining the target charging curve of the energy storage cabinet at the current charging cutoff temperature and the current charging rate from the multiple charging curves that are dynamically updated, so as to perform SOC balancing control on the charging end of the energy storage cabinet; when in the second unilateral balancing control mode, determining the target discharge curve of the energy storage cabinet at the current discharge cutoff temperature and the current discharge rate from the multiple discharge curves that are dynamically updated, so as to perform SOC balancing control on the discharge end of the energy storage cabinet.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a SOC balancing control method and device for an energy storage system, an energy storage system, and a storage medium. Background Art

[0002] At present, wind energy, solar energy and other energy sources have been vigorously promoted and developed in my country, but due to the intermittent and volatile characteristics of such energy sources, it is easy to abandon wind and solar energy. The energy storage system composed of multiple energy storage cabinets with large-capacity batteries can solve this problem well. In order to give full play to the performance of the energy storage system, it is necessary to use the voltage-SOC (State of Charge) curve of the battery cell for balanced control to ensure that the charge state of each single battery in the energy storage cabinet is as consistent as possible when it is fully charged or discharged, so as to avoid performance degradation or safety problems caused by uneven power.

[0003] In the related art, usually all energy storage cabinets deploy SOC balancing solutions of charge-discharge bilateral balancing control or pure voltage threshold balancing judgment based on the SOC difference represented by the same voltage-SOC curve under fixed charge-discharge voltage thresholds tested offline in the energy storage system. However, in the above-mentioned balancing control method, the voltage-SOC curve tested offline can only represent the sample characteristics of a few battery cells, which has certain or large differences from the working characteristics of the battery cells during the actual operation of the energy storage cabinet on site, and the balancing control method can only adapt to the fixed voltage threshold working condition, and cannot be flexibly adjusted according to the working condition application requirements, resulting in a large deviation in the calculated SOC accuracy, which is prone to misbalancing or over-balancing problems. Summary of the invention

[0004] The present invention provides a method, device, energy storage system and storage medium for SOC balancing control of an energy storage system, so as to at least solve the technical problem that the voltage-SOC curve based on the balancing control method in the related art can only adapt to the fixed voltage threshold working condition, and cannot be flexibly adjusted according to the working condition application requirements, thereby causing the calculated SOC accuracy to have a large deviation, and is prone to wrong balancing or over-balancing. The technical solution of the present invention is as follows:

[0005] According to a first aspect of an embodiment of the present invention, there is provided a SOC balancing control method for an energy storage system, which is applied to an energy storage system, wherein the energy storage system comprises a plurality of energy storage cabinets, each of the plurality of energy storage cabinets corresponds to a preset curve library one by one, and the method comprises: for any energy storage cabinet, determining a target balancing control mode matching the operating condition of the energy storage cabinet from a plurality of balancing control models; when the target balancing control mode is a first unilateral balancing control mode, determining a target charging curve of the energy storage cabinet at a current charging cut-off temperature and a current charging rate from a plurality of charging curves in a preset curve library associated with the energy storage cabinet; and, based on the target charging curve, performing SOC balancing control is performed, and the multiple charging curves are fitted based on multiple groups of actual charging voltage dynamic data of the energy storage cabinet during the charging operation to characterize the correlation mapping relationship between the charging voltage and the SOC; when the target balancing control mode is the second unilateral balancing control mode, the target discharge curve of the energy storage cabinet at the current discharge cut-off temperature and the current discharge rate is determined from multiple discharge curves in the preset curve library; and based on the target discharge curve, SOC balancing control is performed on the discharge end of the energy storage cabinet, and the multiple discharge curves are fitted based on multiple groups of actual discharge voltage dynamic data of the energy storage cabinet during the discharge operation to characterize the correlation mapping relationship between the discharge voltage and the SOC.

[0006] In one implementation, a target balancing control mode matching the operating condition of the energy storage cabinet is determined from a plurality of balancing control models, including: when it is determined that the operating interval of the energy storage cabinet is in a first SOC interval, a first unilateral balancing control mode is determined as the target balancing control mode; the first SOC interval indicates an operating interval in which the energy storage cabinet is fully charged and not fully discharged; when it is determined that the operating interval of the energy storage cabinet is in a second SOC interval, a second unilateral balancing control mode is determined as the target balancing control mode; the second SOC interval indicates an operating interval in which the energy storage cabinet is not fully charged and is fully discharged.

[0007] In another implementation, each group of actual charging voltage dynamic data includes the actual charging cut-off temperature, actual charging rate, actual charging voltage and actual charging SOC value of each battery cell in the energy storage cabinet; each group of actual discharge voltage dynamic data includes the actual discharge cut-off temperature, actual discharge rate, actual discharge voltage and actual discharge SOC value of each battery cell in the energy storage cabinet;

[0008] Determining a target charging curve of the energy storage cabinet at a current charging cut-off temperature and a current charging rate from a plurality of charging curves in a preset curve library associated with the energy storage cabinet, including: determining a first charging cut-off cell from a plurality of cells of the energy storage cabinet, selecting a plurality of candidate charging curves at a target actual charging cut-off temperature and a target actual charging rate that match the current charging cut-off temperature and the current charging rate from a plurality of charging curves associated with the first charging cut-off cell; fitting the plurality of candidate charging curves to obtain a target charging curve;

[0009] Determining a target discharge curve of an energy storage cabinet at a current discharge cut-off temperature and a current discharge rate from a plurality of discharge curves in a preset curve library includes: determining a first discharge cut-off cell from a plurality of cells in the energy storage cabinet, selecting a plurality of candidate discharge curves at a target actual discharge cut-off temperature and a target actual discharge rate that match the current discharge cut-off temperature and the current discharge rate from a plurality of discharge curves associated with the first discharge cut-off cell; and fitting the plurality of candidate discharge curves to obtain a target discharge curve.

[0010] In another implementation, before determining the target balancing control mode matching the operating condition of the energy storage cabinet from the multiple balancing control models, the method further includes:

[0011] The energy storage cabinet is controlled to start operation, and the actual charging voltage dynamic data and the actual discharging voltage dynamic data generated by the energy storage cabinet during the start operation phase are detected and collected according to a preset collection cycle; the data storage time interval is determined according to the storage space of the energy storage cabinet chip used to store data; the data storage time interval is greater than the collection time interval between adjacent preset collection cycles; according to the data storage time interval, multiple target preset collection cycles whose time intervals between collection times are the same as the data storage time interval are selected from each preset collection cycle, and the actual charging voltage dynamic data and the actual discharging voltage dynamic data collected by the multiple target preset collection cycles are respectively determined as multiple groups of actual charging voltage dynamic data and multiple groups of actual discharging voltage dynamic data; the multiple groups of actual charging voltage dynamic data are fitted to obtain multiple charging curves respectively included in each battery cell of the energy storage cabinet; the multiple groups of actual discharging voltage dynamic data are fitted to obtain multiple discharge curves respectively included in each battery cell of the energy storage cabinet.

[0012] The multiple charging curves respectively included in each battery cell of the energy storage cabinet obtained above can be understood as multiple charging curves of each battery cell that is first charged and terminated at each actual charging cut-off temperature and each actual charging rate.

[0013] The multiple discharge curves respectively included in each battery cell of the energy storage cabinet obtained above can be understood as multiple discharge curves of each battery cell that is first discharged and cut off at each actual discharge cut-off temperature and each actual discharge rate.

[0014] The first charging cut-off cell is different under different charging cut-off temperatures and different charging rates; the first discharging cut-off cell is also different under different discharging cut-off temperatures and different discharging rates.

[0015] In another implementation, the method further includes: associating the target charging curve with each battery cell of the energy storage cabinet and storing them in a preset curve library, and, when the number of charging curves associated with each battery cell and stored in the preset curve library is greater than a preset number, deleting the charging curves that exceed the preset number in sequence according to the order of storage time; associating the target discharge curve with each battery cell of the energy storage cabinet and storing them in the preset curve library, and, when the number of discharge curves associated with each battery cell and stored in the preset curve library is greater than a preset number, deleting the discharge curves that exceed the preset number in sequence according to the order of storage time.

[0016] As an implementation method, the association between the target charging curve and the first charging cut-off cell, the current discharge cut-off temperature and the current discharge rate corresponding to the energy storage cabinet is stored in a preset curve library. Based on this, when the number of charging curves associated with the first charging cut-off cell corresponding to the target charging curve is greater than a preset number, the charging curves associated with the first charging cut-off cell exceeding the preset number are deleted in order of storage time.

[0017] As another implementation method, the association between the target discharge curve and the first discharge cut-off cell corresponding to the energy storage cabinet, the current discharge cut-off temperature and the current discharge rate is stored in a preset curve library. Based on this, when the number of discharge curves associated with the first discharge cut-off cell corresponding to the target discharge curve is greater than a preset number, the discharge curves associated with the first discharge cut-off cell exceeding the preset number are deleted in order of storage time.

[0018] In another implementation, based on the target charging curve, SOC balancing control is performed on the charging end of the energy storage cabinet, including: when the energy storage system is in a fully charged state, determining, according to the target charging curve, each first SOC value of each of the multiple battery cells of the energy storage cabinet at the corresponding first battery cell voltage; and determining the first average voltage of each first battery cell voltage of the multiple battery cells; selecting at least one first target battery cell whose first battery cell voltage is greater than the first average voltage from the multiple battery cells and determining the first SOC value corresponding to the first target battery cell as the first target SOC value, and selecting a second target battery cell whose voltage deviation between the first battery cell voltage and the first average voltage is the smallest from the multiple battery cells and determining the first SOC value corresponding to the second target battery cell as the second target SOC value; for any first target battery cell, determining the first balancing time of any first target battery cell according to the SOC difference between the first target SOC value and the second target SOC value of any first target battery cell, and performing discharge processing on any first target battery cell according to the first balancing time.

[0019] In another implementation, based on the target discharge curve, SOC balancing control is performed on the discharge end of the energy storage cabinet, including: when the energy storage system is in a fully discharged state, according to the target discharge curve, determining each second SOC value of each battery cell in the multiple battery cells of the energy storage cabinet at each corresponding second battery cell voltage; and determining the second average voltage of each second battery cell voltage of the multiple battery cells; selecting at least one second target battery cell whose second battery cell voltage is greater than the second average voltage from the multiple battery cells and determining the second SOC value corresponding to the second target battery cell as the third target SOC value, and selecting a fourth target battery cell whose voltage deviation between the second battery cell voltage and the second average voltage is the smallest from the multiple battery cells and determining the second SOC value corresponding to the fourth target battery cell as the fourth target SOC value; for any second target battery cell, determining the second balancing time of any second target battery cell according to the SOC difference between the third target SOC value and the fourth target SOC value of any second target battery cell, and performing discharge processing on any second target battery cell according to the second balancing time.

[0020] According to a second aspect of an embodiment of the present invention, there is provided an energy storage system SOC balancing control device, which is applied to an energy storage system, wherein the energy storage system includes a plurality of energy storage cabinets, each of the plurality of energy storage cabinets is provided with a one-to-one corresponding preset curve library, and the device includes: a mode determination unit, which is used to determine, for any energy storage cabinet, a target balancing control mode that matches the operating condition of the energy storage cabinet from a plurality of balancing control models; a first balancing control unit, which is used to determine, when the target balancing control mode is a first unilateral balancing control mode, a target charging curve of the energy storage cabinet at a current charging cut-off temperature and a current charging rate from a plurality of charging curves in the preset curve library associated with the energy storage cabinet; and based on the target charging curve , performing SOC balancing control on the charging end of the energy storage cabinet, wherein the multiple charging curves are fitted based on multiple groups of actual charging voltage dynamic data during the charging operation of the energy storage cabinet and are used to characterize the correlation mapping relationship between the charging voltage and the SOC; a second balancing control unit is used to determine the target discharge curve of the energy storage cabinet at the current discharge cut-off temperature and the current discharge rate from multiple discharge curves in a preset curve library when the target balancing control mode is the second unilateral balancing control mode; and based on the target discharge curve, performing SOC balancing control on the discharge end of the energy storage cabinet, wherein the multiple discharge curves are fitted based on multiple groups of actual discharge voltage dynamic data during the discharge operation of the energy storage cabinet and are used to characterize the correlation mapping relationship between the discharge voltage and the SOC.

[0021] According to a third aspect of an embodiment of the present invention, an energy storage system is provided, which includes a plurality of energy storage cabinets, each of the plurality of energy storage cabinets being provided with a one-to-one corresponding preset curve library to implement the energy storage system SOC balancing control method as described in the first aspect and any possible implementation method thereof.

[0022] According to a fourth aspect of an embodiment of the present invention, a control device is provided, comprising: a processor and a memory for storing processor executable instructions; wherein the processor is configured to execute executable instructions to implement an energy storage system SOC balancing control method such as the first aspect and any possible implementation thereof.

[0023] According to a fifth aspect of an embodiment of the present invention, a computer-readable storage medium is provided, on which instructions are stored. When the instructions in the computer-readable storage medium are executed by a processor of a computer device, the computer device is enabled to execute the energy storage system SOC balancing control method such as the first aspect and any possible implementation thereof.

[0024] According to a sixth aspect of an embodiment of the present application, a computer program product is provided, the computer program product comprising computer instructions, which, when executed on a computer device, enables the computer device to execute the energy storage system SOC balancing control method of the first aspect and any possible implementation thereof.

[0025] The technical solution provided by the embodiment of the present invention brings at least the following beneficial effects: corresponding preset curve libraries are set for different energy storage cabinets, and each preset curve library is respectively provided with a charging curve and a discharging curve fitted based on the actual charging voltage dynamic data and the actual discharging voltage dynamic data, so that the charging curve and / or the discharging curve based on the balancing control process are generated based on the relevant dynamic data generated by the energy storage cabinet itself in the actual operating condition, thereby ensuring that the charging curve and / or the discharging curve stored in the preset curve library of the energy storage cabinet is more in line with the operating condition of the energy storage cabinet, so that the above-mentioned charging curve and the discharging curve can more accurately characterize the correlation mapping relationship between voltage and SOC. At the same time, according to the operating condition of the energy storage cabinet, the unilateral balancing control mode matching the time operating condition requirement is flexibly adjusted, and the charging end or the discharging end is unilaterally balanced according to the charging curve or the discharging curve corresponding to the control mode, so as to ensure that the SOC balancing control process can be flexibly adjusted based on the operating condition requirement, thereby improving the flexibility and accuracy of the SOC balancing control method.

[0026] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application, and do not constitute an improper limitation on the present application.

[0028] Figure 1 is a schematic block diagram of an energy storage system according to an exemplary embodiment;

[0029] Figure 2 The following is a flow chart of a method for SOC balancing control of an energy storage system according to an exemplary embodiment. Figure 1 ;

[0030] Figure 3 The following is a flow chart of a method for SOC balancing control of an energy storage system according to an exemplary embodiment. Figure 2 ;

[0031] Figure 4 is a schematic block diagram of a SOC balancing control device for an energy storage system according to an exemplary embodiment;

[0032] Figure 5 is a schematic diagram of a control device according to an exemplary embodiment. DETAILED DESCRIPTION

[0033] In order to enable ordinary persons in the art to better understand the technical solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0035] Before introducing in detail the SOC balancing control method for the energy storage system provided in the embodiment of the present application, a brief introduction is first given to the application scenarios and implementation architecture involved in the embodiment of the present application.

[0036] First, the application scenario of the SOC balancing control method of the energy storage system of the present application is described as follows.

[0037] At present, my country's wind energy, solar energy and other energy sources have been vigorously promoted and developed, but due to the intermittent and volatile characteristics of this type of energy, it is easy to abandon wind and light. The energy storage system composed of multiple energy storage cabinets with large-capacity batteries can solve this problem well. In order to give full play to the performance of the energy storage system, it is necessary to use the voltage-SOC (State of Charge) curve of the battery cell for balanced control to ensure that the power of each single battery in the energy storage cabinet can be kept consistent as much as possible to avoid performance degradation or safety problems caused by uneven power.

[0038] In the related art, usually all energy storage cabinets deploy SOC balancing solutions of charge-discharge bilateral balancing control or pure voltage threshold balancing judgment based on the SOC difference represented by the same voltage-SOC curve under fixed charge-discharge voltage thresholds tested offline in the energy storage system. However, in the above-mentioned balancing control method, the voltage-SOC curve tested offline can only represent the sample characteristics of a few battery cells, which has certain or large differences from the working characteristics of the battery cells during the actual operation of the energy storage cabinet on site, and the balancing control method can only adapt to the fixed voltage threshold working condition, and cannot be flexibly adjusted according to the working condition application requirements, resulting in a large deviation in the calculated SOC accuracy, which is prone to misbalancing or over-balancing problems.

[0039] Research has found that the voltage-SOC curve obtained by offline testing can only adapt to the fixed charge and discharge cut-off voltage threshold conditions. When the user modifies the charge and discharge voltage cut-off threshold, the offline voltage-SOC curve cannot be applied. In addition, as the battery cell continues to decay during long-term use, the deviation of the offline voltage-SOC curve will gradually increase.

[0040] Therefore, it is urgent to develop a control algorithm that can autonomously learn and update the voltage-SOC curve online according to the actual operating status of the energy storage cabinet, so as to meet the application requirements of different charging and discharging voltage cut-off thresholds, continuous attenuation of battery cells, and large differences in battery cell voltage consistency.

[0041] Furthermore, the current balancing algorithms mostly use pure voltage threshold judgment or charging and discharging bilateral SOC judgment solutions. The accuracy of balancing time calculation and the flexibility of working condition application are difficult to coordinate. It is urgent to develop a balancing control system with high accuracy and flexible triggering.

[0042] In response to the above problems, the present application provides a method for SOC balancing control of an energy storage system, wherein corresponding preset curve libraries are respectively set for different energy storage cabinets, and each preset curve library is respectively provided with a charging curve and a discharging curve fitted based on actual charging voltage dynamic data and actual discharging voltage dynamic data, so that the charging curve and / or discharging curve used in the balancing control process is generated based on the relevant dynamic data generated by the energy storage cabinet itself in the actual operating condition, thereby ensuring that the charging curve and / or discharging curve stored in the preset curve library of the energy storage cabinet is more in line with the operating condition of the energy storage cabinet, so that the above charging curve and discharging curve can more accurately characterize the correlation mapping relationship between voltage and SOC. At the same time, according to the operating condition of the energy storage cabinet, the unilateral balancing control mode that matches the time operating condition requirements is flexibly adjusted, and the charging end or the discharging end is unilaterally balanced according to the charging curve or discharging curve corresponding to the control mode, so as to ensure that the SOC balancing control process can be flexibly adjusted based on the operating condition requirements, thereby improving the flexibility and accuracy of the SOC balancing control method.

[0043] Secondly, the implementation framework of the SOC balancing control method of the energy storage system of the present application is explained as follows.

[0044] like Figure 1 As shown, the energy storage system includes multiple energy storage cabinets 10, and each energy storage cabinet 10 includes multiple batteries 101. Among them, each battery is connected to a corresponding balancing circuit 102, so that the battery cell is discharged evenly through the on-off control of the MOS tube in the balancing circuit 102. Multiple batteries 101 form a battery pack.

[0045] In some embodiments, for easy identification, each energy storage cabinet 10 is marked with an energy storage cabinet number representing a unique identifier, and each of the batteries 101 is marked with a battery number representing a unique battery identifier.

[0046] In some embodiments, the energy storage cabinet 10 may be a lithium battery energy storage cabinet, and the battery may be a lithium iron phosphate battery.

[0047] The energy storage system autonomously learns and updates the voltage-SOC curve online according to the actual operating status of each energy storage cabinet 10, and adopts the updated voltage-SOC curve to implement the corresponding balancing control strategy to meet the application requirements of different charging and discharging voltage cut-off thresholds, continuous attenuation of battery cells, and large differences in battery cell voltage consistency.

[0048] The above-mentioned balancing control strategies include charging unilateral balancing control, discharging unilateral balancing control, charging and discharging bilateral balancing control and charging and discharging end SOC calibration control strategies.

[0049] The energy storage system SOC balancing control method provided in the embodiment of the present application can be applied to a control device applied to an energy storage system or used for SOC balancing control of an energy storage system. For ease of understanding, the energy storage system SOC balancing control method provided in the present application is specifically introduced below in conjunction with the accompanying drawings.

[0050] Figure 2 is a flow chart of a method for SOC balancing control of an energy storage system according to an exemplary embodiment. Figure 2 As shown, the energy storage system SOC balancing control method includes the following steps.

[0051] S21, for any energy storage cabinet, determining a target balancing control mode that matches the operating condition of the energy storage cabinet from multiple balancing control models.

[0052] The multiple balancing control models include at least a first unilateral balancing control mode and a second unilateral balancing control mode.

[0053] S22, when the target balancing control mode is the first unilateral balancing control mode, determining a target charging curve of the energy storage cabinet at the current charging cut-off temperature and the current charging rate from a plurality of charging curves in a preset curve library associated with the energy storage cabinet; and, based on the target charging curve, performing SOC balancing control on the charging end of the energy storage cabinet.

[0054] The multiple charging curves are based on the fitting of multiple sets of actual charging voltage dynamic data during the charging operation of the energy storage cabinet, and are used to characterize the correlation mapping relationship between the charging voltage and SOC.

[0055] S23, when the target balancing control mode is the second unilateral balancing control mode, determining the target discharge curve of the energy storage cabinet at the current discharge cut-off temperature and the current discharge rate from multiple discharge curves in the preset curve library; and performing SOC balancing control on the discharge end of the energy storage cabinet based on the target discharge curve.

[0056] The multiple discharge curves are based on the fitting of multiple groups of actual discharge voltage dynamic data during the discharge operation of the energy storage cabinet, and are used to characterize the correlation mapping relationship between the discharge voltage and SOC.

[0057] Each energy storage cabinet in the above energy storage system is provided with a corresponding preset curve library, which is also called a voltage-SOC curve library.

[0058] It is understandable that the charging curve and the discharging curve in each preset curve library are obtained by fitting the actual voltage dynamic data of the energy storage cabinet, that is, different preset curve libraries include different charging curves and discharging curves. The above operation can be performed for each energy storage cabinet in the energy storage system to achieve balanced control.

[0059] Through the above implementation, corresponding preset curve libraries are set for different energy storage cabinets, and each preset curve library is respectively provided with a charging curve and a discharging curve fitted based on the actual charging voltage dynamic data and the actual discharging voltage dynamic data, so that the charging curve and / or discharging curve used in the balancing control process is generated based on the relevant dynamic data generated by the energy storage cabinet itself in the actual operating condition, thereby ensuring that the charging curve and / or discharging curve stored in the preset curve library of the energy storage cabinet is more in line with the operating condition of the energy storage cabinet, so that the above charging curve and discharging curve can more accurately characterize the correlation mapping relationship between voltage and SOC. At the same time, according to the operating condition of the energy storage cabinet, the unilateral balancing control mode that matches the time operating condition requirements is flexibly adjusted, and the charging end or the discharging end is unilaterally balanced according to the charging curve or discharging curve corresponding to the control mode, so as to ensure that the SOC balancing control process can be flexibly adjusted based on the operating condition requirements, thereby improving the flexibility and accuracy of the SOC balancing control method.

[0060] As a refinement and extension of the specific implementation of the above embodiment, in order to fully illustrate the specific implementation process of this embodiment, the embodiment of the present application provides other implementation methods of the SOC balancing control method of the energy storage system.

[0061] Combination Figure 2 like Figure 3 As shown, the method for determining the target balancing control mode in the above step S21 can be specifically implemented through the following steps.

[0062] S211, when it is determined that the operation range of the energy storage cabinet is in the first SOC range, determining the first unilateral balancing control mode as the target balancing control mode.

[0063] The first SOC interval indicates an operating interval in which the energy storage cabinet is fully charged and not fully discharged.

[0064] S212: When it is determined that the operation range of the energy storage cabinet is in the second SOC range, the second unilateral balancing control mode is determined as the target balancing control mode.

[0065] The second SOC interval indicates an operating interval in which the energy storage cabinet is neither fully charged nor fully discharged.

[0066] According to this implementation, if the energy storage cabinet operates in a fully charged but not fully discharged SOC interval, a charging curve is selected for balancing. If the energy storage cabinet operates in a not fully charged but not fully discharged SOC interval, a discharging curve is selected for balancing.

[0067] As an implementation mode, each group of actual charging voltage dynamic data includes the actual charging cut-off temperature, actual charging rate, actual charging voltage and actual charging SOC value of each battery cell in the energy storage cabinet; each group of actual discharge voltage dynamic data includes the actual discharge cut-off temperature, actual discharge rate, actual discharge voltage and actual discharge SOC value of each battery cell in the energy storage cabinet.

[0068] Based on this implementation, in one implementation, the specific process of determining the target charging curve of the energy storage cabinet at the current charging cut-off temperature and the current charging rate from the multiple charging curves in the preset curve library associated with the energy storage cabinet in the above step S22 is specifically implemented through the following steps.

[0069] First, a first charging cut-off cell is determined from multiple cells in the energy storage cabinet, and multiple candidate charging curves under a target actual charging cut-off temperature and a target actual charging rate that match a current charging cut-off temperature and a current charging rate are selected from multiple charging curves associated with the first charging cut-off cell.

[0070] It is understandable that in actual operation of the energy storage cabinet, the cell that is first charged is called the first charging cut-off cell. Multiple candidate curves of the first charging cut-off cell can be used as candidate charging curves for the remaining cells of the energy storage cabinet.

[0071] Second, multiple candidate charging curves are fitted to obtain a target charging curve;

[0072] In one embodiment, the specific process of determining the target discharge curve of the energy storage cabinet at the current discharge cut-off temperature and the current discharge rate from the multiple discharge curves in the preset curve library in the above step S23 is specifically implemented through the following steps.

[0073] First, a first discharge cutoff cell is determined from multiple cells in the energy storage cabinet; and multiple candidate discharge curves at a target actual discharge cutoff temperature and a target actual discharge rate that match a current discharge cutoff temperature and a current discharge rate are selected from multiple discharge curves associated with the first discharge cutoff cell.

[0074] It is understandable that in actual operation of the energy storage cabinet, the cell that is discharged first is called the cell that is discharged first. Multiple candidate curves of the cell that is discharged first can be used as candidate charging curves for the remaining cells of the energy storage cabinet.

[0075] Second, multiple candidate discharge curves are fitted to obtain a target discharge curve.

[0076] In order to ensure the accuracy of the balancing control, the actual voltage dynamic data is generated and obtained in real time when the energy storage cabinet is started before executing the balancing control, so as to generate the charging curve and the discharging curve based on the actual voltage dynamic data. The actual voltage dynamic data includes the actual discharge voltage dynamic data and the actual charge voltage dynamic data.

[0077] Specifically, before determining a target balancing control mode that matches the operating condition of the energy storage cabinet from a plurality of balancing control models, the charging curve and the discharging curve are obtained in the following manner.

[0078] First, the energy storage cabinet is controlled to start operation, and the actual charging voltage dynamic data and the actual discharging voltage dynamic data generated by the energy storage cabinet during the startup operation phase are detected, and the detected dynamic data are collected according to a preset collection cycle.

[0079] The above-mentioned startup operation stage is a stage for acquiring actual charging voltage dynamic data and actual discharging voltage dynamic data to realize real-time collection of voltage dynamic data, so as to obtain charging curve and discharging curve by fitting.

[0080] During the startup operation phase, the energy storage system controls each energy storage cabinet to operate in different operating modes and adopts different balancing control strategies for balancing, so as to obtain multiple sets of actual charging voltage dynamic data and multiple sets of actual discharging voltage dynamic data under different control strategies and different operating conditions.

[0081] Secondly, the data storage time interval is determined according to the storage space of the energy storage cabinet chip used to store data; the data storage time interval is greater than the collection time interval between adjacent preset collection cycles.

[0082] In some implementations, the data storage time interval is a positive integer multiple of the collection time interval between adjacent preset collection cycles.

[0083] Third, according to the data storage time interval, multiple target preset collection periods whose time intervals between collection times are the same as the data storage time interval are selected from each preset collection period, and the actual charging voltage dynamic data and the actual discharging voltage dynamic data collected by the multiple target preset collection periods are respectively determined as multiple groups of actual charging voltage dynamic data and multiple groups of actual discharging voltage dynamic data.

[0084] In the above steps, in order to avoid excessive storage space occupied by storing the voltage dynamic data used for fitting, the voltage dynamic data collected in each preset collection period is screened according to the data storage time interval.

[0085] It should be noted that when the energy storage cabinet is in a factory state, that is, before operation, the preset curve library includes an initial voltage-SOC curve obtained by using offline data, and the initial voltage-SOC curve is a static curve.

[0086] Fourthly, multiple groups of actual charging voltage dynamic data are fitted to obtain multiple charging curves of each battery cell of the energy storage cabinet.

[0087] The multiple charging curves respectively included in each battery cell of the energy storage cabinet obtained above can be understood as multiple charging curves of each battery cell that is first charged and terminated at each actual charging cut-off temperature and each actual charging rate.

[0088] Fifth, multiple groups of actual discharge voltage dynamic data are fitted to obtain multiple discharge curves of each battery cell of the energy storage cabinet.

[0089] The multiple discharge curves respectively included in each battery cell of the energy storage cabinet obtained above can be understood as multiple discharge curves of each battery cell that is first discharged and cut off at each actual discharge cut-off temperature and each actual discharge rate.

[0090] Through this implementation, autonomous learning and autonomous generation of the voltage-SOC curve are achieved.

[0091] As an implementation mode, the above-mentioned groups of actual charging voltage dynamic data and the groups of actual charging voltage dynamic data can be determined based on the following data collected at different times: the voltage of each battery cell in the energy storage cabinet, the maximum voltage of the battery cell, the minimum voltage of the battery cell, the current of the energy storage system, the average temperature of the energy storage system, the energy storage ampere-hour integrated throughput, the current rated capacity of the energy storage system and the system working status and other parameters.

[0092] In some specific embodiments, by collecting the actual ampere-hour throughput and voltage parameters of the charging terminal and the discharging terminal, the actual SOC at each collected voltage of the charging and discharging terminal is calculated based on the judgment that the data is valid.

[0093] Further, according to the data storage interval requirements of the voltage-SOC curve library, the calculated charge-discharge voltage-SOC curve is processed to obtain the dynamic voltage-SOC curve at the current temperature and rate discrete point, and then stored. The latest curve that needs to be updated to the voltage-SOC curve library is obtained by mean fitting the three voltage-SOC curves at the same temperature and rate discrete point that were recently stored.

[0094] Furthermore, combined with the voltage-SOC curve library after real-time data update, the charging cut-off SOC of each cell is interpolated and calculated according to the voltage of each cell at the charging cut-off time. At the same time, the cell position to be balanced whose charging cut-off voltage is above the average value and whose deviation from the average value is the smallest is selected. According to the charging cut-off SOC of the cell to be balanced and the deviation of the SOC of the cell near the average value of the charging cut-off voltage, the maximum balancing time of each cell to be balanced is calculated, so as to achieve balancing of the cells to be balanced by controlling the opening of the MOS tube of the balancing circuit.

[0095] Optionally, considering the influence of errors, balancing is a multiple and dynamic process. After each charging reaches the balancing calculation condition, the cells to be balanced and the balancing time are recalculated. When the average voltage at the end of charging exceeds the balancing start voltage threshold 1, the system reaches a relatively balanced state.

[0096] Through this implementation, the dynamic voltage-SOC curve is continuously identified online during the charge and discharge process, and the different rate and temperature curves in the voltage-SOC curve library are updated. This parameter online identification solution can, on the one hand, identify the differences in cabinet charge and discharge characteristics caused by the inconsistency of the battery cells online; on the other hand, it can automatically adapt to the differences in the charge and discharge terminal voltage-SOC curve caused by the change of the charge and discharge cut-off voltage threshold and the aging and attenuation of the battery cells, and comprehensively improve the interpolation accuracy of the dynamic voltage-SOC curve library.

[0097] In some embodiments, SOC balancing control is performed according to a preset control cycle, and actual charging voltage dynamic data and multiple groups of actual discharging voltage dynamic data collected in a preset control cycle before the current preset control cycle are used for fitting to update the charging curve and the discharging curve in the preset curve library in the energy storage cabinet.

[0098] Furthermore, in order to be more consistent with the current operating conditions, actual charging voltage dynamic data and multiple groups of actual discharging voltage dynamic data collected in a preset number of preset control cycles that are continuously adjacent to the current preset control cycle are used for fitting.

[0099] Optionally, the curves in the preset curve library are updated in the following manner to improve the timeliness of the stored curves. The target charging curve is associated with each battery cell of the energy storage cabinet and stored in the preset curve library, and when the number of charging curves associated with each battery cell stored in the preset curve library is greater than a preset number, the charging curves exceeding the preset number are deleted in sequence according to the order of storage time. The target discharge curve is associated with each battery cell of the energy storage cabinet and stored in the preset curve library, and when the number of discharge curves associated with each battery cell stored in the preset curve library is greater than a preset number, the discharge curves exceeding the preset number are deleted in sequence according to the order of storage time.

[0100] As an implementation method, the association between the target charging curve and the first charging cut-off cell, the current discharge cut-off temperature and the current discharge rate corresponding to the energy storage cabinet is stored in a preset curve library. Based on this, when the number of charging curves associated with the first charging cut-off cell corresponding to the target charging curve is greater than a preset number, the charging curves associated with the first charging cut-off cell exceeding the preset number are deleted in order of storage time.

[0101] As another implementation method, the association between the target discharge curve and the first discharge cut-off cell corresponding to the energy storage cabinet, the current discharge cut-off temperature and the current discharge rate is stored in a preset curve library. Based on this, when the number of discharge curves associated with the first discharge cut-off cell corresponding to the target discharge curve is greater than a preset number, the discharge curves associated with the first discharge cut-off cell exceeding the preset number are deleted in order of storage time.

[0102] The target charging curve and the target discharging curve are used to update the charging curve and the discharging curve stored in the preset curve library, so that the updated charging curve and the discharging curve are used for balancing the next time when the control balancing is performed.

[0103] In some embodiments, based on the actual charging voltage and the actual charging SOC value at the actual charging cut-off temperature and the actual charging rate, an interpolation algorithm is used to update the preset charging cut-off temperature and the preset charging rate in the preset curve library, where the deviation from the actual charging cut-off temperature and the actual charging rate is less than a preset deviation threshold.

[0104] Optionally, in order to ensure the timeliness of the curve data in the subsequent preset curve library, the target charging curve and the target discharging curve are associated with each battery cell of the energy storage cabinet and stored in the preset curve library.

[0105] Based on the above implementation mode, in order to prevent calculation interpolation errors, each time the full charge equalization calculation condition is reached, the battery cells to be equalized and the equalization time are recalculated and updated, and the battery cells with high charging cut-off voltage are gradually discharged evenly to increase the charging time of the battery cells with lower charging voltage in the next charging process, increase the average charging cut-off voltage, and thus improve the system capacity.

[0106] As an implementation manner, the SOC balancing control of the charging end of the energy storage cabinet based on the target charging curve in the above S22 specifically includes the following steps.

[0107] First, when the energy storage system is in a fully charged state, the first SOC values ​​of each of the multiple battery cells in the energy storage cabinet at the corresponding first battery cell voltages are determined according to the target charging curve; and the first average voltage of the first battery cell voltages of the multiple battery cells is determined.

[0108] The above-mentioned fully charged state can be understood as the SOC of the energy storage system = 100% when the charging is cut off.

[0109] Secondly, at least one first target battery cell whose first battery cell voltage is greater than the first average voltage is selected from the multiple battery cells, and the first SOC value corresponding to the first target battery cell is determined as the first target SOC value; and a second target battery cell whose voltage deviation between the first battery cell voltage and the first average voltage is the smallest is selected from the multiple battery cells, and the first SOC value corresponding to the second target battery cell is determined as the second target SOC value.

[0110] The first target cell is also called a cell to be balanced.

[0111] Each of the multiple battery cells of the energy storage cabinet has a corresponding first battery cell voltage, also called a charging cut-off voltage.

[0112] Third, for any first target battery cell, a first balancing time of any first target battery cell is determined according to an SOC difference between a first target SOC value and a second target SOC value of any first target battery cell, and any first target battery cell is discharged according to the first balancing time.

[0113] Specifically, performing discharge processing on any first target battery cell according to the first balancing time includes: controlling a MOS tube in the balancing circuit to be turned on, and controlling the MOS tube to be turned off when the MOS tube turn-on time reaches the first balancing time.

[0114] As an implementation mode, in the above S22, based on the target discharge curve, SOC balancing control is performed on the discharge end of the energy storage cabinet, which specifically includes the following steps.

[0115] First, when the energy storage system is in a fully discharged state, the second SOC values ​​of each of the multiple battery cells in the energy storage cabinet at the corresponding second battery cell voltages are determined according to the target discharge curve; and the second average voltage of each of the second battery cell voltages of the multiple battery cells is determined.

[0116] The above-mentioned full discharge state can be understood as when the energy storage system SOC=0% at the discharge cut-off time. Each of the multiple cells of the above-mentioned energy storage cabinet has a corresponding second cell voltage, also called a discharge cut-off voltage.

[0117] Secondly, at least one second target battery cell whose second battery cell voltage is greater than the second average voltage is selected from the multiple battery cells, and the second SOC value corresponding to the second target battery cell is determined as the third target SOC value; and a fourth target battery cell whose voltage deviation between the second battery cell voltage and the second average voltage is the smallest is selected from the multiple battery cells, and the second SOC value corresponding to the fourth target battery cell is determined as the fourth target SOC value.

[0118] The second target cell is also called a cell to be balanced.

[0119] Third, for any second target battery cell, a second balancing time of any second target battery cell is determined according to the SOC difference between the third target SOC value and the fourth target SOC value of any second target battery cell, and any second target battery cell is discharged according to the second balancing time.

[0120] Specifically, performing discharge processing on any second target battery cell includes: controlling a MOS tube in the balancing circuit to be turned on, and when the MOS tube is turned on for a time period that reaches the second balancing time period, controlling the MOS tube to be turned off.

[0121] In some embodiments, in order to ensure the rationality of the balancing process, after any first target battery cell is discharged and / or any second target battery cell is discharged, each time the full charge balancing calculation condition is reached, that is, each time the charging reaches the balancing calculation condition, a new target charging curve or a target discharge curve determined by the current discharge cut-off temperature and the current discharge rate is re-collected, and the balancing time (that is, the first balancing time and the second balancing time) of the battery cell to be balanced and the battery cell to be balanced is re-determined and recalculated and updated until the balancing control is stopped when the balancing stop condition is met. In this way, by gradually achieving balanced discharge of the battery cells with high charging cut-off voltage, the charging time of the battery cells with low charging voltage in the next charging process is increased, the charging cut-off average voltage is increased, and the system capacity is increased.

[0122] Optionally, the above-mentioned balancing stop condition includes that the difference between the charging cut-off average voltage of each battery cell and the balancing start voltage threshold is greater than a preset difference, for example, the charging cut-off average voltage exceeds the balancing start voltage threshold 1.

[0123] Specifically, as balancing proceeds, when the charging cut-off average voltage exceeds the balancing start voltage threshold 1, the system reaches a relatively balanced state and no longer performs balancing. The balancing start voltage threshold 1 is adjusted according to the charging cut-off voltage threshold.

[0124] Exemplarily, the equalization start voltage threshold may also be the charge cut-off voltage minus 20 mV.

[0125] As a specific implementation, a parameter acquisition module, an online identification module, a to-be-balanced cell detection module, and a balancing time calculation and execution module are provided in the energy storage system. The specific balancing process is as follows.

[0126] First, a parameter acquisition module is used to obtain voltage dynamic data related to battery parameters in the energy storage cabinet during the charging and discharging process.

[0127] Specifically, the system working status of the energy storage cabinet is obtained in real time through CAN communication. St (t) , System charge and discharge current I (t), Voltage of each battery cell V i (t)、 Maximum cell voltage Vmax(t), Minimum cell voltage Vmin(t), Average cell temperature T(t), Current rated capacity of the system Q e 、 The system's cumulative charge and discharge ampere-hour throughput at each moment Ah(t) wait.

[0128] The system working state includes but is not limited to charging, discharging, standby, and shutdown states; the system charging and discharging current is defined as discharging as positive and charging as negative.

[0129] The above-mentioned charge-discharge ampere-hour throughput is the result of measurement based on the ampere-hour integration algorithm; the variable i Representative i Cells; t Represents the sampling time.

[0130] Secondly, the dynamic voltage-SOC mapping curve is identified online through an online identification module.

[0131] The online recognition module includes a charging voltage-SOC mapping curve online recognition unit and a discharging voltage-SOC mapping curve online recognition unit.

[0132] Before the energy storage cabinet leaves the factory, the voltage-SOC curve library at different temperatures and different magnifications is set with initial offline data. The temperature range in the voltage-SOC curve library is discretized at intervals of 5°C, and the magnification range is discretized at intervals of 0.1C.

[0133] (1) In the online identification unit of the charging voltage-SOC mapping curve, the energy storage cabinet records the ampere-hour integrated throughput from the highest voltage reaching 3.38V to the end of charging each time. The time recording interval is determined according to actual needs. If the system SOC≠100% at the end of charging, the data record is invalid and no subsequent identification is performed. If the system SOC=100% at the end of charging, the data record is valid and subsequent identification can be performed.

[0134] First, as shown in formula (1), the actual SOC at each recording time under the current temperature of the charging terminal and the current charging rate is calculated based on the ampere-hour integral change and the rated capacity of the energy storage system. real1 , and further combined with the cabinet's highest charging voltage at each recording moment, that is, different charging cut-off voltages, to obtain a charging terminal voltage-SOC curve with denser data intervals, that is, the initial charging curve.

[0135] Formula (1).

[0136] Where t represents the current recording time; t1 represents the time when the system SOC = 100%; Ah represents the system ampere-hour throughput, charging is negative growth, and discharging is positive growth; Q e Represents the rated capacity of the system.

[0137] Then, the charge cut-off temperature T is calculated according to the following formula (2) and formula (3): cha and charging rate C cha The interval division process is performed to match the variable interval division in the voltage-SOC curve library.

[0138] Formula (2).

[0139] Formula (3).

[0140] Wherein, T represents the average temperature of the battery cell; I is the system charge and discharge current, which is negative for charging and positive for discharging; and round function is the rounding function.

[0141] Further, according to the data storage interval in the voltage-SOC curve library, the charging terminal voltage-SOC curve is interpolated and converted to obtain T cha Temperature discrete points and C cha At the discrete rate point, the voltage-SOC curve that needs to be stored in this charging cycle is recorded as curve1_T cha C cha。 By analogy, we can get each voltage-SOC curve curve2_T cha C cha and curve3_T cha C cha For chip data storage space considerations, only the three most recent voltage-SOC curves are stored at each voltage and temperature point, and then fitted according to the following formula (4) to obtain the fitted voltage-SOC curve curve_T cha C cha .

[0142] Formula (4).

[0143] Among them, SOC TchaCcha is curve_T cha C cha SOC values ​​corresponding to different voltage discrete points in the curve; SOC1 TchaCcha is curve1_T cha C cha SOC values ​​corresponding to different voltage discrete points; SOC2 TchaCcha curve2_T cha C chaSOC values ​​corresponding to different voltage discrete points; SOC3 TchaCcha curve3_T cha C cha The SOC values ​​corresponding to different voltage discrete points in the fitting curve are shown in Figure 2, and k represents the voltage discrete point in the fitting curve.

[0144] Finally, the above curve_T cha C cha The curve is updated to the voltage-SOC curve library to realize online identification of a charging curve.

[0145] (2) In the discharge voltage-SOC mapping curve online identification unit, the energy storage cabinet records the ampere-hour integrated throughput from the lowest voltage reaching 3.15V to the end of discharge each time the energy storage cabinet discharges. The time recording interval is determined according to actual needs. If the system SOC≠0% at the end of discharge, the data recorded this time is invalid and no subsequent identification is performed. If the system SOC=0% at the end of discharge, the recorded data is valid and subsequent identification can be performed.

[0146] First, as shown in formula (5), the actual SOC at each recording time under the current temperature and current discharge rate conditions is calculated based on the ampere-hour integral change and the system rated capacity. real2 , and further combined with the cabinet's minimum discharge voltage at each recording moment, the discharge terminal voltage-SOC curve with dense data intervals is obtained. It should be noted that the actual SOC calculated here is not equivalent to the system SOC obtained in the parameter acquisition module. The main reason is that the system SOC often has inaccurate measurement problems due to factors such as the ampere-hour integral accumulation error.

[0147] Formula (5).

[0148] Among them, t represents the current recording time; t2 represents the time when the system SOC=0; Ah represents the system ampere-hour throughput, with current charging as a negative count and discharging as a positive count; Qe represents the system rated capacity.

[0149] Then, the discharge cut-off temperature T is calculated according to the following formula (6) and formula (7): dis and discharge rate C dis The interval division process is performed to match the variable interval division in the voltage-SOC curve library.

[0150] Formula (6).

[0151] Formula (7).

[0152] Furthermore, according to the data storage interval in the voltage-SOC curve library, the discharge end voltage-SOC curve is interpolated and converted to obtain Tdis Temperature discrete points and C dis At the discrete rate point, the voltage-SOC curve that needs to be stored in this discharge cycle is recorded as curve1_T dis C dis。 By analogy, we get curve2_T dis C dis and curve3_T dis C dis Etc., and then fit according to the following formula (8) to obtain the fitted voltage-SOC curve curve_T dis C dis .

[0153] Formula (8).

[0154] Among them, SOC TdisCdis is curve_T dis C dis SOC values ​​corresponding to different voltage discrete points in the curve; SOC1 TdisCdis is curve1_T dis C dis SOC values ​​corresponding to different voltage discrete points; SOC2 TdisCdis curve2_T dis C dis SOC values ​​corresponding to different voltage discrete points; SOC3 TdisCdis curve3_T dis C dis The SOC values ​​corresponding to different voltage discrete points in the fitting curve; k represents the discrete points of the battery cell in the fitting curve.

[0155] Finally, curve_T dis C dis The curve is updated to the voltage-SOC curve library to realize online identification of a discharge curve.

[0156] In the above implementation, the dynamic voltage-SOC curve is continuously identified online during the charging and discharging process, so that the different rate and temperature curves in the voltage-SOC curve library are updated. This parameter online identification solution can, on the one hand, identify online the differences in cabinet charging and discharging characteristics caused by the inconsistency of the battery cells; on the other hand, it can automatically adapt to the differences in the charging and discharging terminal voltage-SOC curve caused by the changes in the charging and discharging cut-off voltage threshold and the aging and attenuation of the battery cells, and comprehensively improve the interpolation accuracy of the dynamic voltage-SOC curve library.

[0157] Thirdly, a cell detection module to be balanced is used to detect the cell to be balanced according to the voltage at the charging cut-off time.

[0158] When the system SOC=100% at the charging cutoff time, based on the voltage-SOC curve library, the charging cutoff voltage set V(t1)=[V1(t1), V2(t1), ..., Vn(t1)], system charging current I(t1), and battery cell average temperature T(t1) of each battery cell at this moment are used as input for interpolation to obtain the charging cutoff SOC value data set SOC(t1)= [SOC1(t1), SOC2(t1), ..., SOCn(t1)] of all battery cells, where n is the number of battery cells.

[0159] Calculate the average voltage at the end of charging, recorded as V avg , and find the cell with the smallest deviation from the average voltage, record its cell number as Num0, the cells to be balanced are the cells whose charging cut-off voltage is above the average value, record these cell numbers in the data set Num=[Num1,Num2, ...,Num m ], where m is the number of cells to be balanced.

[0160] Fourthly, the balancing time calculation and execution module calculates the balancing time of the battery cells to be balanced according to the evaluation of the battery cells to be balanced in the above-mentioned "battery cells to be balanced detection module" using the following formula (9), and the balancing time is Time (Num).

[0161] Formula (9).

[0162] Wherein, Num is the number of the battery cell to be balanced; η For balancing efficiency, hardware sampling and balancing are usually performed alternately. The balancing efficiency is the duty cycle of the balancing time within a unit algorithm scheduling cycle. b To balance the current, each cell in the balancing circuit is connected in parallel with a balancing resistor. The balancing control of the cells to be balanced is achieved by controlling the MOS tube to be turned on and off. The balancing current is the current passing through the balancing resistor.

[0163] After calculating the balancing time, the MOS tube in the balancing circuit is controlled to be turned on according to the number of the cell to be balanced, and the cells are discharged evenly. When the balancing time of a cell reaches its calculated value Time (Num), the MOS tube is controlled to be turned off, ending the balancing.

[0164] In order to prevent calculation interpolation errors, each time the full charge equalization calculation conditions are reached, the equalization cells to be equalized and the equalization time are recalculated and updated, and the cells with high charging cut-off voltages are gradually discharged evenly to increase the charging time of the cells with lower charging voltages in the next charging process, increase the average charging cut-off voltage, and thus increase the system capacity.

[0165] As balancing proceeds, when the average charge cut-off voltage exceeds the equalization start voltage threshold 1, the system reaches a relative equilibrium state and no longer performs balancing. The equalization start voltage threshold 1 is adjusted according to the charge cut-off voltage threshold, which can be optionally the charge cut-off voltage minus 20mV.

[0166] Optionally, the to-be-balanced detection module may also detect the to-be-balanced cells according to the voltage at the discharge cut-off time.

[0167] When the system SOC=0% at the discharge cut-off time, based on the latest identified discharge voltage-SOC curve in the voltage-SOC curve library, the discharge cut-off voltage set V(t2)=[V1(t2), V2(t2), ..., Vn(t2)], system charging current I(t2), and battery cell average temperature T(t2) of each battery cell at this moment are used as input for interpolation to obtain the discharge cut-off SOC data set SOC(t2)= [SOC1(t2), SOC2(t2), ..., SOCn(t2)] of all battery cells, where n is the number of battery cells.

[0168] Calculate the average voltage at the discharge cut-off time, recorded as V avg , and find the average voltage V avg The cell with the smallest deviation is numbered as Num0. The cells to be balanced are the cells whose discharge cut-off voltage is above the average value. The data set Num=[Num1, Num2, ..., Num m ], where m is the number of cells to be balanced.

[0169] The unilateral balancing control strategy can be selected based on the charging cut-off voltage-SOC curve in the voltage-SOC curve library to perform charging end balancing. The final effect is that the voltage of all cells is maintained in the high voltage range (such as the charging cut-off voltage minus 20mV) at the charging cut-off time.

[0170] The unilateral balancing control strategy can also be selected based on the discharge cut-off voltage-SOC curve in the voltage-SOC curve library to perform discharge end balancing. The final effect is that the voltage of all cells is maintained in a low voltage range (such as the discharge cut-off voltage plus 20mV) at the discharge cut-off time.

[0171] Both of the above-mentioned balancing methods can ultimately achieve the optimal energy utilization state and can be selected according to application requirements.

[0172] This unilateral balancing control strategy can effectively identify the cells to be balanced and accurately control the balancing time of each cell. Compared with the balancing strategy based on charge and discharge bilateral judgment, this solution is more flexible in terms of working conditions. Especially when there is a large amount of reserved discharge power in the power station operation strategy, the discharge terminal voltage is in a plateau period, and the discharge terminal SOC cannot be calculated by interpolation based on the dynamic voltage-SOC curve, which makes it impossible to implement the balancing strategy based on charge and discharge bilateral judgment.

[0173] In order to realize the above functions, the SOC balancing control device of the energy storage system includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should easily realize that, in combination with the algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0174] The present application also provides a method Figure 4 The energy storage system SOC balancing control device shown is applied to an energy storage system, which includes multiple energy storage cabinets, each of which is provided with a one-to-one corresponding preset curve library. The device includes: a mode determination unit 401, a first balancing control unit 402, a second balancing control unit 403 and a data acquisition unit 404.

[0175] The mode determination unit 401 is used to determine, for any energy storage cabinet, a target balancing control mode that matches the operating condition of the energy storage cabinet from multiple balancing control models.

[0176] The first balancing control unit 402 is used to determine, when the target balancing control mode is the first unilateral balancing control mode, a target charging curve of the energy storage cabinet at the current charging cut-off temperature and the current charging rate from a plurality of charging curves in a preset curve library associated with the energy storage cabinet; and, based on the target charging curve, perform SOC balancing control on the charging end of the energy storage cabinet, wherein the plurality of charging curves are fitted based on a plurality of groups of actual charging voltage dynamic data of the energy storage cabinet during the charging operation and are used to characterize the associated mapping relationship between the charging voltage and the SOC.

[0177] The second balancing control unit 403 is used to determine the target discharge curve of the energy storage cabinet at the current discharge cut-off temperature and the current discharge rate from the multiple discharge curves in the preset curve library when the target balancing control mode is the second unilateral balancing control mode; and based on the target discharge curve, perform SOC balancing control on the discharge end of the energy storage cabinet, the multiple discharge curves are based on multiple groups of actual discharge voltage dynamic data fitting during the discharge operation of the energy storage cabinet to characterize the correlation mapping relationship between the discharge voltage and the SOC.

[0178] In one embodiment, the mode determination unit 401 is specifically used to: when it is determined that the operating range of the energy storage cabinet is in a first SOC range, determine the first unilateral balancing control mode as the target balancing control mode; the first SOC range indicates an operating range in which the energy storage cabinet is fully charged and not fully discharged; when it is determined that the operating range of the energy storage cabinet is in a second SOC range, determine the second unilateral balancing control mode as the target balancing control mode; the second SOC range indicates an operating range in which the energy storage cabinet is not fully charged and is fully discharged.

[0179] In one embodiment, each group of actual charging voltage dynamic data includes the actual charging cut-off temperature, actual charging rate, actual charging voltage and actual charging SOC value of each battery cell in the energy storage cabinet; each group of actual discharge voltage dynamic data includes the actual discharge cut-off temperature, actual discharge rate, actual discharge voltage and actual discharge SOC value of each battery cell in the energy storage cabinet;

[0180] The first balancing control unit 402 is used to determine the first charging cut-off cell from the multiple cells of the energy storage cabinet, select multiple candidate charging curves at the target actual charging cut-off temperature and the target actual charging rate that match the current charging cut-off temperature and the current charging rate from the multiple charging curves associated with the first charging cut-off cell; fit the multiple candidate charging curves to obtain the target charging curve;

[0181] The second balancing control unit 403 is used to determine the first discharge cut-off battery cell from the multiple battery cells of the energy storage cabinet, select multiple candidate discharge curves under the target actual discharge cut-off temperature and the target actual discharge rate that match the current discharge cut-off temperature and the current discharge rate from the multiple discharge curves associated with the first discharge cut-off battery cell; fit the multiple candidate discharge curves to obtain the target discharge curve.

[0182] In one embodiment, the device further includes: a data acquisition unit 404, which is used to control the start-up operation of the energy storage cabinet, and detect the actual charging voltage dynamic data and the actual discharging voltage dynamic data generated by the energy storage cabinet during the start-up operation stage, and collect the data according to a preset acquisition cycle; determine the data storage time interval according to the storage space of the energy storage cabinet chip used to store data; the data storage time interval is greater than the collection time interval between adjacent preset collection cycles; according to the data storage time interval, select multiple target preset collection cycles whose time intervals between collection times are the same as the data storage time interval from each preset collection cycle, and respectively determine the actual charging voltage dynamic data and the actual discharging voltage dynamic data collected by the multiple target preset collection cycles as multiple groups of actual charging voltage dynamic data and multiple groups of actual discharging voltage dynamic data; fit the multiple groups of actual charging voltage dynamic data to obtain multiple charging curves respectively included in each battery cell of the energy storage cabinet; fit the multiple groups of actual discharging voltage dynamic data to obtain multiple discharge curves respectively included in each battery cell of the energy storage cabinet.

[0183] The multiple charging curves respectively included in each battery cell of the energy storage cabinet obtained above can be understood as multiple charging curves of each battery cell that is first charged and terminated at each actual charging cut-off temperature and each actual charging rate.

[0184] The multiple discharge curves respectively included in each battery cell of the energy storage cabinet obtained above can be understood as multiple discharge curves of each battery cell that is first discharged and cut off at each actual discharge cut-off temperature and each actual discharge rate.

[0185] In one embodiment, the data acquisition unit 404 is further used to: associate the target charging curve with each battery cell of the energy storage cabinet and store them in a preset curve library, and, when the number of charging curves associated with each battery cell and stored in the preset curve library is greater than a preset number, delete the charging curves that exceed the preset number in order of storage time; associate the target discharge curve with each battery cell of the energy storage cabinet and store them in the preset curve library, and, when the number of discharge curves associated with each battery cell and stored in the preset curve library is greater than a preset number, delete the discharge curves that exceed the preset number in order of storage time.

[0186] As an implementation mode, the data acquisition unit 404 is further used to store the association between the target charging curve and the first charging cut-off battery cell corresponding to the energy storage cabinet, the current discharge cut-off temperature and the current discharge rate in a preset curve library. Based on this, when the number of charging curves associated with the first charging cut-off battery cell corresponding to the target charging curve is greater than a preset number, the charging curves associated with the first charging cut-off battery cell exceeding the preset number are deleted in order of storage time.

[0187] As another embodiment, the data acquisition unit 404 is further used to store the association between the target discharge curve and the first discharge cut-off battery cell corresponding to the energy storage cabinet, the current discharge cut-off temperature and the current discharge rate in a preset curve library. Based on this, when the discharge curve associated with the first discharge cut-off battery cell corresponding to the target discharge curve is greater than a preset number, the discharge curves associated with the first discharge cut-off battery cell exceeding the preset number are deleted in order of storage time.

[0188] In one embodiment, the first balancing control unit 402 is specifically used to: when the energy storage system is in a fully charged state, determine, according to the target charging curve, each first SOC value of each battery cell in the multiple battery cells of the energy storage cabinet at the corresponding first battery cell voltage; and determine the first average voltage of each first battery cell voltage of the multiple battery cells; select at least one first target battery cell whose first battery cell voltage is greater than the first average voltage from the multiple battery cells and determine the first SOC value corresponding to the first target battery cell as the first target SOC value, and select a second target battery cell whose voltage deviation between the first battery cell voltage and the first average voltage is the smallest from the multiple battery cells and determine the first SOC value corresponding to the second target battery cell as the second target SOC value; for any first target battery cell, determine the first balancing time of any first target battery cell according to the SOC difference between the first target SOC value and the second target SOC value of any first target battery cell, and discharge any first target battery cell according to the first balancing time.

[0189] In one embodiment, the second balancing control unit 403 is specifically used to: when the energy storage system is in a fully discharged state, determine, according to the target discharge curve, each second SOC value of each battery cell in the multiple battery cells of the energy storage cabinet at the corresponding second battery cell voltage; and determine the second average voltage of each second battery cell voltage of the multiple battery cells; select at least one second target battery cell whose second battery cell voltage is greater than the second average voltage from the multiple battery cells and determine the second SOC value corresponding to the second target battery cell as the third target SOC value, and select a fourth target battery cell whose voltage deviation between the second battery cell voltage and the second average voltage is the smallest from the multiple battery cells and determine the second SOC value corresponding to the fourth target battery cell as the fourth target SOC value; for any second target battery cell, determine the second balancing time of any second target battery cell according to the SOC difference between the third target SOC value and the fourth target SOC value of any second target battery cell, and discharge any second target battery cell according to the second balancing time.

[0190] Regarding the device in the above embodiment, the specific manner in which each unit module performs the operation has been described in detail in the embodiment of the method, and will not be elaborated here.

[0191] Figure 5is a schematic diagram of a control device provided by this application. Figure 5 The control device 60 may include at least one processor 601 and a memory 603 for storing processor executable instructions. The processor 601 is configured to execute instructions in the memory 603 to implement the energy storage system SOC balancing control method in the following embodiment.

[0192] In addition, the control device 60 may further include a communication bus 602 , at least one communication interface 604 , an input device 606 , and an output device 605 .

[0193] The processor 601 may be a central processing unit (CPU), a microprocessing unit, an ASIC, or one or more integrated circuits for controlling the execution of the program of the present application.

[0194] Communication bus 602 may include a pathway for transmitting information between the above-mentioned components.

[0195] The communication interface 604 uses any transceiver-like device for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.

[0196] The input device 606 is used to receive input signals and the output device 605 is used to output signals.

[0197] The memory 603 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory may exist independently and be connected to the processing unit through a bus. The memory may also be integrated with the processing unit.

[0198] The memory 603 is used to store instructions for executing the solution of the present application, and the execution is controlled by the processor 601. The processor 601 is used to execute the instructions stored in the memory 603, so as to realize the functions in the method of the present application.

[0199] In a specific implementation, as an embodiment, the processor 601 may include one or more CPUs, such as Figure 5 CPU0 and CPU1 in.

[0200] In a specific implementation, as an embodiment, the control device 60 may include multiple processors, such as Figure 5 601 and processor 607 in the embodiment of the present invention. Each of these processors may be a single-CPU processor or a multi-CPU processor. The processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0201] The control device is Figure 5 The system shown includes: a processor 601 and a memory 603 for storing executable instructions of the processor 601; wherein the processor 601 is configured to execute the executable instructions to implement the energy storage system SOC balancing control method of any possible implementation method described above. And the same technical effect can be achieved, so it will not be repeated here to avoid repetition.

[0202] The embodiment of the present application also provides an energy storage system, which is configured to execute any of the above possible implementation methods for energy storage system SOC balancing control, and can achieve the same technical effect, which will not be described here to avoid repetition.

[0203] The embodiment of the present application also provides a computer-readable storage medium, when the instructions in the computer-readable storage medium are executed by the processor of the control device or control equipment, the control device or control equipment can execute the energy storage system SOC balancing control method as any possible implementation method described above. And can achieve the same technical effect, to avoid repetition, it will not be repeated here.

[0204] The embodiment of the present application also provides a computer program product, including a computer program or instruction, which is executed by a processor as a method for SOC balancing control of an energy storage system in any of the above possible implementations. And the same technical effect can be achieved, so it will not be repeated here to avoid repetition.

[0205] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0206] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A SOC balancing control method for an energy storage system, characterized in that: Applied to an energy storage system, the energy storage system includes a plurality of energy storage cabinets, each of the plurality of energy storage cabinets corresponds one-to-one to a preset curve library, the method includes: For any energy storage cabinet, determine a target balancing control mode matching the operating condition of the energy storage cabinet from multiple balancing control models; When the target balancing control mode is the first unilateral balancing control mode, a target charging curve of the energy storage cabinet at the current charging cut-off temperature and the current charging rate is determined from a plurality of charging curves in a preset curve library associated with the energy storage cabinet; and based on the target charging curve, SOC balancing control is performed on the charging end of the energy storage cabinet, wherein the plurality of charging curves are fitted based on a plurality of groups of actual charging voltage dynamic data of the energy storage cabinet during the charging operation and are used to characterize the associated mapping relationship between the charging voltage and the SOC; When the target balancing control mode is the second unilateral balancing control mode, a target discharge curve of the energy storage cabinet at the current discharge cut-off temperature and the current discharge rate is determined from the multiple discharge curves in the preset curve library; and based on the target discharge curve, SOC balancing control is performed on the discharge end of the energy storage cabinet, wherein the multiple discharge curves are based on multiple groups of actual discharge voltage dynamic data fitting during the discharge operation of the energy storage cabinet and are used to characterize the correlation mapping relationship between the discharge voltage and the SOC; The step of determining the target charging curve of the energy storage cabinet at the current charging cut-off temperature and the current charging rate from the multiple charging curves in the preset curve library associated with the energy storage cabinet comprises: determining the first charging cut-off cell from the multiple cells of the energy storage cabinet; selecting multiple candidate charging curves at the target actual charging cut-off temperature and the target actual charging rate that match the current charging cut-off temperature and the current charging rate from the multiple charging curves associated with the first charging cut-off cell; and fitting the multiple candidate charging curves to obtain the target charging curve; The step of determining the target discharge curve of the energy storage cabinet at the current discharge cut-off temperature and the current discharge rate from the multiple discharge curves in the preset curve library comprises: determining the first discharge cut-off cell from the multiple cells of the energy storage cabinet; selecting multiple candidate discharge curves at the target actual discharge cut-off temperature and the target actual discharge rate that match the current discharge cut-off temperature and the current discharge rate from the multiple discharge curves associated with the first discharge cut-off cell; and fitting the multiple candidate discharge curves to obtain the target discharge curve.

2. The method according to claim 1, characterized in that The step of determining a target balancing control mode matching the operating condition of the energy storage cabinet from a plurality of balancing control models includes: When it is determined that the operating interval of the energy storage cabinet is in a first SOC interval, the first unilateral balancing control mode is determined as the target balancing control mode; the first SOC interval indicates an operating interval in which the energy storage cabinet is fully charged and not fully discharged; When it is determined that the operating range of the energy storage cabinet is in a second SOC range, the second unilateral balancing control mode is determined as the target balancing control mode; the second SOC range indicates an operating range in which the energy storage cabinet is not fully charged but fully discharged.

3. The method according to claim 2, characterized in that Each group of actual charging voltage dynamic data includes the actual charging cut-off temperature, actual charging rate, actual charging voltage and actual charging SOC value of each battery cell in the energy storage cabinet; each group of actual discharge voltage dynamic data includes the actual discharge cut-off temperature, actual discharge rate, actual discharge voltage and actual discharge SOC value of each battery cell in the energy storage cabinet.

4. The method according to claim 1, characterized in that Before determining the target balancing control mode matching the operating condition of the energy storage cabinet from the multiple balancing control models, the method further includes: Controlling the energy storage cabinet to start operation, and detecting actual charging voltage dynamic data and actual discharging voltage dynamic data generated by the energy storage cabinet during the startup operation phase, and collecting data according to a preset collection cycle; Determine a data storage time interval according to the storage space of the energy storage cabinet chip used to store data; the data storage time interval is greater than the collection time interval between adjacent preset collection cycles; According to the data storage time interval, multiple target preset collection periods are selected from each preset collection period with the same time interval between collection times as the data storage time interval, and the actual charging voltage dynamic data and the actual discharging voltage dynamic data collected by the multiple target preset collection periods are respectively correspondingly determined as the multiple groups of actual charging voltage dynamic data and the multiple groups of actual discharging voltage dynamic data; Fitting the multiple groups of actual charging voltage dynamic data to obtain multiple charging curves respectively included in each battery cell of the energy storage cabinet; The multiple groups of actual discharge voltage dynamic data are fitted to obtain multiple discharge curves respectively included in each battery cell of the energy storage cabinet.

5. The method according to any one of claims 1 to 4, characterized in that The method further comprises: The target charging curve is associated with each battery cell of the energy storage cabinet and stored in the preset curve library; and when the number of charging curves associated with each battery cell and stored in the preset curve library is greater than a preset number, the charging curves exceeding the preset number are deleted in sequence according to the order of storage time; The target discharge curve is associated with each battery cell of the energy storage cabinet and stored in the preset curve library; and when the discharge curves associated with each battery cell and stored in the preset curve library are greater than a preset number, the discharge curves exceeding the preset number are deleted in sequence according to the order of storage time.

6. The method according to any one of claims 1 to 4, characterized in that The performing SOC balancing control on the charging end of the energy storage cabinet based on the target charging curve includes: When the energy storage system is in a fully charged state, determining, according to the target charging curve, each first SOC value of each battery cell in the multiple battery cells of the energy storage cabinet at each corresponding first battery cell voltage; and determining a first average voltage of each first battery cell voltage of the multiple battery cells; Selecting at least one first target battery cell whose first battery cell voltage is greater than the first average voltage from the multiple battery cells and determining a first SOC value corresponding to the first target battery cell as a first target SOC value, and selecting a second target battery cell whose first battery cell voltage has a minimum voltage deviation from the first average voltage from the multiple battery cells and determining the first SOC value corresponding to the second target battery cell as a second target SOC value; For any first target battery cell, a first balancing time of the any first target battery cell is determined according to an SOC difference between a first target SOC value of the any first target battery cell and the second target SOC value, and the any first target battery cell is discharged according to the first balancing time.

7. The method according to any one of claims 1 to 4, characterized in that The performing SOC balancing control on the discharge end of the energy storage cabinet based on the target discharge curve includes: When the energy storage system is in a fully discharged state, determining, according to the target discharge curve, each second SOC value of each battery cell in the multiple battery cells of the energy storage cabinet at each corresponding second battery cell voltage; and determining a second average voltage of each second battery cell voltage of the multiple battery cells; Selecting at least one second target battery cell whose second battery cell voltage is greater than the second average voltage from the multiple battery cells and determining a second SOC value corresponding to the second target battery cell as a third target SOC value, and selecting a fourth target battery cell whose second battery cell voltage has the smallest voltage deviation from the second average voltage from the multiple battery cells and determining the second SOC value corresponding to the fourth target battery cell as a fourth target SOC value; For any second target battery cell, a second balancing time of the any second target battery cell is determined according to the SOC difference between the third target SOC value and the fourth target SOC value of the any second target battery cell, and the any second target battery cell is discharged according to the second balancing time.

8. A SOC balancing control device for an energy storage system, characterized in that: Applied to an energy storage system, the energy storage system includes a plurality of energy storage cabinets, each of the plurality of energy storage cabinets is provided with a one-to-one corresponding preset curve library, the device includes: A mode determination unit, used to determine, for any energy storage cabinet, a target balancing control mode matching the operating condition of the energy storage cabinet from a plurality of balancing control models; A first balancing control unit, configured to determine, when the target balancing control mode is the first unilateral balancing control mode, a target charging curve of the energy storage cabinet at a current charging cut-off temperature and a current charging rate from a plurality of charging curves in a preset curve library associated with the energy storage cabinet; and, based on the target charging curve, perform SOC balancing control on the charging end of the energy storage cabinet, wherein the plurality of charging curves are fitted based on a plurality of groups of actual charging voltage dynamic data of the energy storage cabinet during the charging operation and are used to characterize the associated mapping relationship between the charging voltage and the SOC; a second balancing control unit, for determining, when the target balancing control mode is the second unilateral balancing control mode, a target discharge curve of the energy storage cabinet at a current discharge cut-off temperature and a current discharge rate from a plurality of discharge curves in the preset curve library; and for performing SOC balancing control on a discharge end of the energy storage cabinet based on the target discharge curve, wherein the plurality of discharge curves are fitted based on a plurality of groups of actual discharge voltage dynamic data of the energy storage cabinet during the discharge operation process and are used to characterize the correlation mapping relationship between the discharge voltage and the SOC; The first balancing control unit is specifically used to: determine the first charging cut-off cell from the multiple cells of the energy storage cabinet; select multiple candidate charging curves under the target actual charging cut-off temperature and the target actual charging rate that match the current charging cut-off temperature and the current charging rate from the multiple charging curves associated with the first charging cut-off cell; fit the multiple candidate charging curves to obtain the target charging curve; The second balancing control unit is specifically used to: determine the first discharge cut-off battery cell from the multiple battery cells of the energy storage cabinet; select multiple candidate discharge curves under the target actual discharge cut-off temperature and the target actual discharge rate that match the current discharge cut-off temperature and the current discharge rate from the multiple discharge curves associated with the first discharge cut-off battery cell; fit the multiple candidate discharge curves to obtain the target discharge curve.

9. An energy storage system, characterized in that: The energy storage system comprises a plurality of energy storage cabinets, each of which is provided with a one-to-one corresponding preset curve library, and is configured to execute the energy storage system SOC balancing control method according to any one of claims 1 to 7.

10. A computer-readable storage medium having instructions stored thereon, characterized in that: When the instructions in the computer-readable storage medium are executed by a processor, the energy storage system SOC balancing control method according to any one of claims 1 to 7 can be executed.

Images