A high-power energy storage system and soc automatic correction method

Abstract

The application discloses a kind of high-power energy storage systems and SOC automatic correction method, wherein system includes battery PACK group, cluster level manager, grid-connected inverter and local EMS;The battery PACK group is connected to DC bus by the cluster level manager;The grid-connected inverter is connected between the DC bus and power grid;The local EMS is respectively communicated with the grid-connected inverter and at least two cluster level managers connection.The application can realize cluster level equalization by providing battery PACK group, cluster level manager, grid-connected inverter and local EMS, so that different battery PACK can be directly connected in parallel, with high battery conversion efficiency, low cost, small footprint, easy to expand and other advantages, improve the safety of system, with wide market application prospect.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, and in particular to a high-power energy storage system and an automatic SOC correction method. Background Technology

[0002] Currently, in large-scale electrochemical energy storage systems, the number of battery clusters installed and the number of battery cells connected in series in each cluster are relatively large. Due to the inconsistency in the internal resistance, voltage, and SOC (State of Charge) between battery clusters, circulating currents will form between battery clusters when multiple battery clusters are connected in parallel, resulting in poor battery temperature uniformity and affecting the system's conversion efficiency.

[0003] Existing solutions to the problem of parallel circulating current in battery clusters involve adding DC-DC (Direct Current to Direct Current) devices of the same power level in parallel or assigning a separate PCS (Power Conversion System) to each battery cluster for full-power DC-DC conversion. This not only increases the system cost and sacrifices system efficiency, but also makes it difficult to expand the system by assigning a single PCS to each cluster.

[0004] Therefore, improvements to existing technologies are necessary.

[0005] The above information is provided as background information only to aid in understanding this disclosure and does not constitute an assertion or admission that any of the above content can be used as prior art relative to this disclosure. Summary of the Invention

[0006] This invention provides a high-power energy storage system and an automatic SOC correction method to address the shortcomings of existing technologies.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, embodiments of the present invention provide a high-power energy storage system, the system comprising a battery pack 10, a cluster manager 20, a grid-connected inverter 30, and a local EMS 40; wherein...

[0009] The battery pack 10 is connected to the DC bus via the cluster manager 20;

[0010] The grid-connected inverter 30 is connected between the DC bus and the power grid;

[0011] The local EMS40 is communicatively connected to the grid-connected inverter 30 and at least two of the cluster-level managers 20.

[0012] Furthermore, in the high-power energy storage system, the cluster-level manager 20 includes a cluster-level equalizer 21, a cluster-level BMS 22, a data acquisition device 23, a first switch 24, and a second switch 25;

[0013] One end of the battery pack 10 is connected to the negative terminal of the DC bus through the cluster equalizer 21, and the other end of the battery pack 10 is connected to the positive terminal of the DC bus through the first switch 24.

[0014] The second switch 25 is connected in parallel across the two ends of the cluster equalizer 21;

[0015] The voltage sampling terminal of the acquisition device 23 is connected to the positive and negative terminals of the DC bus, respectively, and the current sampling terminal of the acquisition device 23 is connected between the cluster equalizer 21 and the negative terminal of the DC bus.

[0016] The cluster-level BMS22 is connected to the cluster-level equalizer 21, the acquisition device 23, and the battery pack 10, respectively.

[0017] Furthermore, in the high-power energy storage system, the cluster-level equalizer 21 is powered by the DC bus;

[0018] Alternatively, the cluster equalizer 21 may be powered by the battery pack 10;

[0019] Alternatively, the cluster-level equalizer 21 may be powered by the power grid.

[0020] Furthermore, in the high-power energy storage system, the system also includes a fuse 50;

[0021] The grid-connected inverter 30 is connected in series with the DC bus.

[0022] The fuse 50 is connected in series between the first switch 24 and the positive terminal of the DC bus;

[0023] The fuse 50 is connected in series between the cluster equalizer 21 and the negative terminal of the DC bus.

[0024] Furthermore, in the high-power energy storage system, the battery PACK 10 includes at least two battery PACKs 11;

[0025] At least two of the battery packs 11 are connected in series.

[0026] Furthermore, in the high-power energy storage system, the cluster-level equalizer 21 includes a controllable equalization power supply 211;

[0027] At least two of the battery packs 11 connected in series are connected as a whole to the balanced controllable power supply 211.

[0028] Furthermore, in the high-power energy storage system, the cluster-level equalizer 21 includes at least two equalization controllable power supplies 211 corresponding to at least two of the battery PACK11;

[0029] Each of the at least two battery packs 11 connected in series is connected to a corresponding equalization controllable power supply 211.

[0030] Furthermore, in the high-power energy storage system, the balanced controllable power supply 211 includes a bidirectional DC-DC converter.

[0031] Furthermore, the high-power energy storage system also includes a remote EMS;

[0032] The remote EMS is connected to the local EMS40.

[0033] In a second aspect, embodiments of the present invention provide a method for automatic SOC correction, which is performed using a high-power energy storage system as described in the first aspect above, the method comprising:

[0034] During charging or discharging, the current and voltage of the battery pack are collected;

[0035] The SOC of the battery pack is calculated based on the collected current and voltage.

[0036] Determine whether the deviation of the SOC is greater than a preset value;

[0037] If the deviation of the SOC is greater than the preset value, then return to the step of collecting the current and voltage of the battery pack during the charging or discharging process;

[0038] If the deviation of the SOC is not greater than the preset value, then it is determined whether it is in the end of the charging and discharging period;

[0039] If it is not in the final stage of charging or discharging, the calibration is complete;

[0040] If it is in the final stage of charging or discharging, the error factor K is calculated, and the SOC is calibrated, and the calibration ends.

[0041] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0042] The present invention provides a high-power energy storage system and an automatic SOC correction method. By providing a battery pack, a cluster manager, a grid-connected inverter, and a local EMS, cluster-level balancing can be achieved, allowing different battery packs to be directly connected in parallel. It has advantages such as high battery conversion efficiency, low cost, small footprint, and easy expansion, and improves system safety, thus having broad market application prospects. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of a high-power energy storage system provided in Embodiment 1 of the present invention;

[0045] Figure 2 This is a schematic diagram of the cluster-level equalizer provided in Embodiment 1 of the present invention;

[0046] Figure 3 This is a schematic diagram of the cluster-level equalizer provided in Embodiment 1 of the present invention;

[0047] Figure 4 This is a schematic diagram of the structure of the balanced and controllable power supply provided in Embodiment 1 of the present invention;

[0048] Figure 5 This is a schematic diagram of the control loop of the cluster-level manager provided in Embodiment 1 of the present invention;

[0049] Figure 6 This is a flowchart illustrating an automatic SOC correction method provided in Embodiment 2 of the present invention.

[0050] Figure label:

[0051] 10 battery packs, 20 cluster managers, 30 grid-connected inverters, 40 local EMS, and 50 fuses.

[0052] Battery PACK11;

[0053] Cluster level equalizer 21, cluster level BMS 22, data acquisition device 23, first switch 24, second switch 25;

[0054] Balanced and controllable power supply 211. Detailed Implementation

[0055] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0056] In the description of this invention, it should be understood that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component present simultaneously. When a component is considered to be "set" on another component, it can be directly set on the other component or there may be an intermediate component present simultaneously.

[0057] Furthermore, terms such as “long,” “short,” “inner,” and “outer” indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings. They are used only for the purpose of describing the present invention and are not intended to indicate or imply that the device or component referred to must have this specific orientation or operate in a specific orientational configuration. Therefore, they should not be construed as limitations of the present invention.

[0058] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0059] Example 1

[0060] In view of the aforementioned deficiencies in existing parallel battery technology, the applicant, based on years of extensive practical experience and professional knowledge in the design and manufacture of such products, and in conjunction with the application of theoretical principles, has actively conducted research and innovation in order to create a technology that can overcome the shortcomings of existing technologies and make parallel battery technology more practical. After continuous research, design, and repeated prototype production and improvement, this invention with real practical value has finally been created.

[0061] Please refer to Figure 1 This invention provides a high-power energy storage system, which includes a battery pack 10, a cluster manager 20, a grid-connected inverter 30, and a local EMS 40; wherein,

[0062] The battery pack 10 is connected to the DC bus via the cluster manager 20;

[0063] The grid-connected inverter 30 is connected between the DC bus and the power grid;

[0064] The local EMS40 is communicatively connected to the grid-connected inverter 30 and at least two of the cluster-level managers 20.

[0065] It should be noted that the battery PACK group 10 and the cluster-level manager 20 form an energy storage array, providing a DC bus to the grid-connected inverter 30. The grid-connected inverter 30 is connected to the power grid to realize energy interaction with the power grid.

[0066] This system adopts a two-level BMS architecture. The battery pack 10 is the first-level BMS, and the cluster manager 20 has a built-in second-level BMS. The system energy scheduling is uniformly coordinated and managed through the local EMS (energy management system) 40.

[0067] Please refer to this again. Figure 1 In this embodiment, the cluster-level manager 20 includes a cluster-level equalizer 21, a cluster-level BMS 22, a data acquisition device 23, a first switch 24, and a second switch 25.

[0068] One end of the battery pack 10 is connected to the negative terminal of the DC bus through the cluster equalizer 21, and the other end of the battery pack 10 is connected to the positive terminal of the DC bus through the first switch 24.

[0069] The second switch 25 is connected in parallel across the two ends of the cluster equalizer 21;

[0070] The voltage sampling terminal of the acquisition device 23 is connected to the positive and negative terminals of the DC bus, respectively, and the current sampling terminal of the acquisition device 23 is connected between the cluster equalizer 21 and the negative terminal of the DC bus.

[0071] The cluster-level BMS22 is connected to the cluster-level equalizer 21, the acquisition device 23, and the battery pack 10, respectively.

[0072] The battery pack 10 includes at least two battery packs 11;

[0073] At least two of the battery packs 11 are connected in series.

[0074] The cluster-level equalizer 21 is powered by the DC bus;

[0075] Alternatively, the cluster equalizer 21 may be powered by the battery pack 10;

[0076] Alternatively, the cluster-level equalizer 21 may be powered by the power grid.

[0077] It should be noted that the core of this invention lies in the cluster-level manager 20, which mainly consists of a cluster-level BMS 22 and a cluster-level equalizer 21. The cluster-level BMS 22 has functions such as automatic SOC calibration and SOH prediction, while the cluster-level equalizer 22 has an active equalization compensation function, automatically balancing SOC and voltage. The power input of the cluster-level manager 22 is taken from the system DC bus, a single battery PACK 11, or the AC power grid, and automatically outputs an adaptive voltage to balance the voltage difference that exists when different battery PACK 11s are connected in parallel, thereby achieving inter-cluster equalization of SOC.

[0078] The cluster-level equalizer 21 has a built-in adjustable power supply and uses an innovative method to connect to the battery pack. The controllable power supply provided by the cluster-level equalizer 21 is connected in series between the battery PACK11. By controlling the output voltage of the power supply, it achieves SOC equalization, optimizes the SOC after parallel connection, and thus improves system efficiency and battery utilization.

[0079] In this embodiment, the system further includes a fuse 50;

[0080] The grid-connected inverter 30 is connected in series with the DC bus.

[0081] The fuse 50 is connected in series between the first switch 24 and the positive terminal of the DC bus;

[0082] The fuse 50 is connected in series between the cluster equalizer 21 and the negative terminal of the DC bus.

[0083] Please refer to Figure 2 In one embodiment, the cluster equalizer 21 may include only one equalization controllable power supply 211.

[0084] At least two of the battery packs 11 connected in series are connected as a whole to the balanced controllable power supply 211.

[0085] It should be noted that, in Figure 2 In this process, the cluster-level equalizer 21 adopts an integrated structure, which can achieve equalization control for each cluster of batteries.

[0086] Please refer to Figure 3 In another embodiment, the cluster equalizer 21 may further include at least two equalization controllable power supplies 211 corresponding to at least two of the battery PACK 11.

[0087] Each of the at least two battery packs 11 connected in series is connected to a corresponding equalization controllable power supply 211.

[0088] It should be noted that, in Figure 2In this process, the cluster-level equalizer 21 adopts a modular structure with parallel outputs, enabling equalization control for each PACK.

[0089] The cluster-level manager 20 uses a high-speed communication connection to the outside world, and the communication methods include, but are not limited to, CAN, 485, and 232.

[0090] Please refer to Figure 4 In this embodiment, the balanced controllable power supply 211 includes a bidirectional DC-DC converter.

[0091] It should be noted that the bidirectional DC-DC converter has bidirectional conversion capability. However, since bidirectional DC-DC converters have been implemented in many existing technologies and are not the focus of this design, they will not be elaborated on here.

[0092] In this embodiment, the system also includes a remote EMS;

[0093] The remote EMS is connected to the local EMS40.

[0094] It should be noted that the local EMS40 supports remote scheduling by communicating with a remote EMS.

[0095] In this embodiment, the cluster-level managers 20 of the parallel battery clusters are connected via high-speed communication (CAN communication by default) to exchange information. The parallel online battery clusters compete to sort and find the cluster with the highest voltage. The voltage of the battery cluster is taken as Vmax, and the system soft start is achieved through the cluster-level equalizer 21.

[0096] After the system completes the soft start, the system BMS controls the grid-connected inverter 30 to work according to the scheduling instructions or preset scheduling energy, and the cluster-level manager 20 realizes the balance control. Depending on the power of the grid-connected load, some battery clusters can be put into hibernation.

[0097] When a single cluster is online, the equalizer operates in bypass mode, and the equalizer power supply is not working. When multiple clusters of batteries are connected in parallel, if the voltage and SOC deviation is less than 2% of the preset value (the preset value can be set), each cluster executes the bypass unit, and the DC-DC section does not work. When the deviation exceeds the preset value of 2%, the following equalization strategy is executed, taking the xth cluster as an example.

[0098] Based on the acquired information, the cluster-level manager 20 executes a load balancing strategy, with specific control loops as follows: Figure 5 As shown. The loop includes the voltage and current loops and the equalization adjustment loop of the conventional power supply structure. The core lies in the addition of the equalization adjustment loop and the selection of the equalization coefficient k_x.

[0099] Where k_x is the cluster-level equilibrium coefficient, which is a function of SOC, and k -x= f(SOC), with a value range of 0 to 1, and satisfying k_1+k_2……+k_n=1.

[0100] Itota l is the total output current of the parallel battery on the bus, Itota l*k_x is the command current of this cluster, I fdb_x is the feedback current of this cluster, the deviation is output to the PI regulator, the PI regulation output is the voltage deviation △V_x, which is superimposed on the voltage loop command setpoint.

[0101] The voltage loop is given by Vref_x, which is Vbus-Vbat_x. Vbus is the system bus voltage value, Vbat_x is the voltage value of the cluster, and Vfdb_x is the equalizer power supply output voltage feedback value. The voltage output is given by the current loop Iref_x, and the current loop output is the duty cycle D_x of the cluster equalizer 21 power module output, which is sent to the power PWM unit to control the power supply output.

[0102] In the bidirectional DC-DC converter built into the cluster equalizer 21, the circuit operates in Buck mode when power flows in the forward direction and in Boost mode when power flows in the reverse direction.

[0103] This invention employs an innovative DAB structure, with the filter inductor placed on the output side. The high-frequency voltage and current on the intermediate AC side change simultaneously with the switching action, always maintaining the same direction. This avoids reactive circulating current and enables precise control of the battery's charging and discharging current. Furthermore, the voltage gain of this topology can be achieved by adjusting the turns ratio of the high-frequency transformer or by changing the duty cycle, making it suitable for high-voltage gain applications.

[0104] After the battery PACK11 is connected in series, its voltage is close to that of the DC bus. The power supply of the cluster equalizer 21 only flows through a portion of the power generated or absorbed by the battery, realizing SOC equalization control. This can significantly reduce the rated power of the equalization controllable power supply in the battery cluster, thereby reducing the cost of the energy storage system. The cluster manager 20 innovatively combines the cluster BMS22 with the cluster equalizer 21. The acquisition device 23 and switching devices (i.e., the first switch 24 and the second switch 25, which share a set) and other circuits are highly reused and integrated, which can further reduce the system cost and size.

[0105] Although this document frequently uses terms such as battery pack, cluster manager, grid-connected inverter, local EMS, and fuse, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this invention; interpreting them as any additional limitation would contradict the spirit of this invention.

[0106] The high-power energy storage system provided in this invention provides a battery pack, a cluster manager, a grid-connected inverter, and a local EMS, which can achieve cluster-level balancing, allowing different battery packs to be directly connected in parallel. It has advantages such as high battery conversion efficiency, low cost, small footprint, and easy expansion, and improves system safety, thus having broad market application prospects.

[0107] Example 2

[0108] Please refer to Figure 6 This invention provides an automatic SOC correction method, which is implemented using the high-power energy storage system described in Embodiment 1 above. The method includes:

[0109] S101. During charging or discharging, the current and voltage of the battery pack are collected.

[0110] S102. Calculate the SOC of the battery pack based on the collected current and voltage.

[0111] S103. Determine whether the deviation of the SOC is greater than a preset value. If yes, return to step S101; otherwise, proceed to step S104.

[0112] S104. Determine if the charging / discharging process is in its final stages. If yes, proceed to step S105; otherwise, proceed to step S106.

[0113] S105. Calculate the error factor K and calibrate the SOC.

[0114] S106, Calibration complete.

[0115] The present invention provides an automatic SOC correction method that, by providing a battery pack, a cluster manager, a grid-connected inverter, and a local EMS, can achieve cluster-level balancing, enabling different battery packs to be directly connected in parallel. It has advantages such as high battery conversion efficiency, low cost, small footprint, and easy expansion, and improves system safety, thus having broad market application prospects.

[0116] Thus far, the description of the above embodiments has been provided for illustrative and descriptive purposes. This is not intended to be exhaustive or limiting of the present disclosure. Individual elements or features of particular embodiments are generally not limited to those particular embodiments, but may be interchanged and used in selected embodiments where applicable, even if not specifically shown or described. In many respects, the same elements or features may also be varied. Such variations are not considered a departure from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

[0117] Example embodiments are provided so that this disclosure will become thorough and will fully convey the scope to those skilled in the art. Numerous details, such as examples of specific parts, apparatus, and methods, are set forth to provide a thorough understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that the specific details are not required, and the example embodiments may be implemented in many different forms, neither of which should be construed as limiting the scope of this disclosure. In some example embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0118] Technical terms are used herein for the purpose of describing specific exemplary embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a” and “the” as used herein may also refer to the plural forms. The terms “comprising” and “having” are inclusive and therefore specify the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or additional having of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof. Unless expressly indicated in order of execution, the method steps, processes, and operations described herein are not to be construed as necessarily requiring performance in the specific order discussed and shown. It should also be understood that additional or optional steps may be employed.

[0119] When an element or layer is described as "on," "joined with," "connected to," or "linked to" another element or layer, it may be directly on, joined to, connected to, or linked to another element or layer, or there may be an element or layer in between. Conversely, when an element or layer is described as "directly on," "directly joined with," "directly connected to," or "directly linked to" another element or layer, there may not be an element or layer in between. Other terms used to describe element relationships should be interpreted in a similar manner (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.). The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts are not limited by these terms. These terms may be used only to distinguish one element, component, region, or part from another element, component, region, or part. Unless the context clearly indicates otherwise, the use of terms such as “first,” “second,” and other numerical terms herein does not imply sequence or order. Therefore, the terms “first element,” “component,” “region,” “layer,” or “part” discussed below may be used in the context of “second element,” “component,” “region,” “layer,” or “part” without departing from the teachings of this exemplary embodiment.

[0120] Spatial relative terms, such as “inside,” “outside,” “below,” “under,” “lower,” “above,” “upper,” etc., may be used herein for descriptive purposes to describe the relationship between one element or feature and one or more other elements or features as shown in the figure. Spatial relative terms may refer to different orientations of the device other than those depicted in the figure. For example, if the device in the figure is rotated, an element described as “below other elements or features” or “below the element or feature” will be oriented “above other elements or features.” Therefore, the example term “below” can encompass both upward and downward orientations. The device may be oriented in other ways (rotated 90 degrees or other orientations) and interpreted using the spatial relative descriptions herein.

Claims

1. A high-power energy storage system, characterized in that, The system includes a battery pack (10), a cluster manager (20), a grid-connected inverter (30), and a local EMS (40); wherein, The battery pack (10) is connected to the DC bus via the cluster manager (20); The grid-connected inverter (30) is connected between the DC bus and the power grid; The local EMS (40) is communicatively connected to the grid-connected inverter (30) and at least two of the cluster-level managers (20); The cluster manager (20) includes a cluster equalizer (21), a cluster BMS (22), a data acquisition device (23), a first switch (24), and a second switch (25); One end of the battery pack (10) is connected to the negative terminal of the DC bus through the cluster equalizer (21), and the other end of the battery pack (10) is connected to the positive terminal of the DC bus through the first switch (24). The second switch (25) is connected in parallel across the two ends of the cluster equalizer (21); The voltage sampling terminal of the acquisition device (23) is connected to the positive and negative terminals of the DC bus, respectively, and the current sampling terminal of the acquisition device (23) is connected between the cluster equalizer (21) and the negative terminal of the DC bus. The cluster-level BMS (22) is connected to the cluster-level equalizer (21), the acquisition device (23), and the battery pack (10) respectively. The cluster-level managers (20) connected in parallel are connected by high-speed communication to exchange information. The battery packs (10) of each cluster connected in parallel online are sorted by competition to find the cluster with the highest voltage. The voltage of the battery pack (10) of that cluster is taken as Vmax. The system soft start is realized through the cluster-level equalizer (21). After the system completes the soft start, the system BMS controls the grid-connected inverter (30) to work according to the scheduling instructions or the preset scheduling energy, and the cluster-level manager (20) realizes the balance control.

2. The high-power energy storage system according to claim 1, characterized in that, The cluster-level equalizer (21) is powered by the DC bus; Alternatively, the cluster equalizer (21) may be powered by the battery pack (10); Alternatively, the cluster-level equalizer (21) may be powered by the power grid.

3. The high-power energy storage system according to claim 1, characterized in that, The system also includes a fuse (50); The grid-connected inverter (30) is connected in series with the DC bus. The fuse (50) is connected in series between the first switch (24) and the positive terminal of the DC bus. The fuse (50) is connected in series between the cluster equalizer (21) and the negative terminal of the DC bus.

4. The high-power energy storage system according to claim 1, characterized in that, The battery pack (10) includes at least two battery packs (11). At least two of the battery packs (11) are connected in series.

5. The high-power energy storage system according to claim 4, characterized in that, The cluster-level equalizer (21) includes an equalization controllable power supply (211). At least two of the battery packs (11) connected in series are connected as a whole to the balanced controllable power supply (211).

6. The high-power energy storage system according to claim 4, characterized in that, The cluster equalizer (21) includes at least two equalization controllable power supplies (211) corresponding to at least two of the battery packs (11). Each of the at least two battery packs (11) connected in series is connected to a corresponding equalization controllable power supply (211).

7. The high-power energy storage system according to claim 5 or 6, characterized in that, The balanced controllable power supply (211) includes a bidirectional DC-DC converter.

8. The high-power energy storage system according to claim 1, characterized in that, The system also includes a remote EMS; The remote EMS is connected to the local EMS (40) via communication.

9. A method for automatic SOC calibration, characterized in that, The method is performed using a high-power energy storage system as described in any one of claims 1-8, and includes: During charging or discharging, the current and voltage of the battery pack are collected; The SOC of the battery pack is calculated based on the collected current and voltage. Determine whether the SOC deviation between battery packs in the battery pack is greater than a preset value; If the SOC deviation is greater than the preset value, then return to the step of collecting the current and voltage of the battery pack during the charging or discharging process; If the SOC deviation is not greater than a preset value, then determine whether it is in the final stage of charging or discharging; If it is not in the final stage of charging or discharging, the calibration is complete; If it is in the final stage of charging or discharging, the error factor K is calculated, and the SOC is calibrated, and the calibration ends.

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