Energy storage devices and their charging and discharging control methods, energy storage systems

Abstract

This invention provides an energy storage device and its charging and discharging control method and energy storage system, including a cabinet with a chamber and a ventilation duct, a battery cell located in the chamber, and at least one fan located in the ventilation duct; wherein, at least one fan is connected in series between the battery cell and the power conversion system, and at least one fan is used to absorb the surge current in the charging and discharging circuit between the battery cell and the power conversion system by using the excitation coil of at least one fan as a large inductor during the charging and discharging process of the battery cell and the power conversion system, and to realize soft start charging and discharging, and to send air to the ventilation duct to reduce the temperature of the battery cell and realize energy recovery.

Description

Technical Field

[0001] This invention relates to the field of battery energy storage system technology, specifically to an energy storage device and its charging and discharging control method, and an energy storage system. Background Technology

[0002] With the increasing global demand for renewable energy, energy storage technology, as an important component of new energy, has been widely applied and developed.

[0003] Safety and efficiency are paramount during the charging and discharging of energy storage devices. However, rapid current changes during charging and discharging can generate significant surge currents, which can severely impact downstream low-voltage measurement equipment and even damage it. Furthermore, this surge energy is also wasted.

[0004] Therefore, how to suppress surge current during the charging and discharging process of energy storage devices and reduce energy waste is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To overcome the above-mentioned defects, this invention is proposed to provide an energy storage device and its charging and discharging control method and energy storage system that solve or at least partially solve the technical problem that surge current during the charging and discharging process of energy storage devices causes serious impact on downstream low-voltage measuring equipment and other equipment, resulting in large energy losses.

[0006] In a first aspect, the present invention provides an energy storage device, the energy storage device comprising:

[0007] The cabinet includes a chamber and a ventilation duct;

[0008] The battery cell is located within the cavity;

[0009] At least one fan is located within the ventilation duct;

[0010] The at least one fan is connected in series between the battery cell and the power conversion system. The at least one fan is used to absorb the surge current in the charging and discharging circuit between the battery cell and the power conversion system during the charging and discharging process, and to send air to the ventilation duct to reduce the temperature of the battery cell. The surge current is the current when the current in the charging and discharging circuit is greater than a preset current.

[0011] Furthermore, in the energy storage device described above, the total number of wind turbines is multiple;

[0012] The energy storage device also includes:

[0013] A switching assembly corresponding to each of the multiple wind turbines, the switching assembly being used to connect or remove the respective wind turbine from the charging and discharging circuit;

[0014] A current acquisition device is configured to acquire the current of the charging and discharging circuit;

[0015] A temperature acquisition device is configured to acquire the temperature of the battery cell;

[0016] The controller, electrically connected to the switching assembly, the current acquisition device, and the temperature acquisition device, is configured to, if the current of the charging and discharging circuit is greater than a preset current, determine the first number of fans to be connected based on the current of the charging and discharging circuit and the temperature of the battery cell, and control the switching assemblies corresponding to the first number of fans to connect the first number of fans to the charging and discharging circuit.

[0017] Furthermore, the energy storage device described above also includes:

[0018] A memory, electrically connected to the controller, is used to store historical operating information of each wind turbine;

[0019] The controller is also configured to:

[0020] Based on the historical operating information, the start-up probability of each wind turbine is determined;

[0021] The first number of wind turbines are selected in descending order of their start-up probabilities.

[0022] Furthermore, in the energy storage device described above, the ventilation ducts are located on both sides of the chamber.

[0023] Furthermore, in the energy storage device described above, at least one fan is a DC fan.

[0024] In a second aspect, the present invention provides a charging and discharging control method for an energy storage device, comprising:

[0025] If there are multiple motors in the energy storage device, the current of the charging and discharging circuit and the temperature of the battery cells in the energy storage device are obtained; wherein, the charging and discharging circuit is the circuit between the battery cells and the power conversion system;

[0026] If the current in the charging and discharging circuit is greater than the preset current, the first number of fans to be connected is determined based on the current in the charging and discharging circuit and the temperature of the battery cell.

[0027] Control the first number of fans to connect to the charging and discharging circuit.

[0028] Furthermore, in the above-described energy storage device charging and discharging control method, before controlling the first number of fans to connect to the charging and discharging circuit, the method further includes:

[0029] Based on the historical operating information of each of the plurality of wind turbines, the start-up probability of each wind turbine is determined;

[0030] Select the first number of wind turbines in descending order of their start-up probability.

[0031] Furthermore, in the charging and discharging control method for the energy storage device described above, the historical operating information includes the first operating duration of each wind turbine under different surge currents each time:

[0032] Based on the historical operating information of each of the plurality of wind turbines, the start-up probability of each wind turbine is determined, including:

[0033] The duration for each wind turbine to absorb surge current is determined based on the first operating time and the weights of different surge currents.

[0034] The activation probability is determined based on the duration of the surge current absorption.

[0035] Furthermore, the charging and discharging control method for the energy storage device described above also includes:

[0036] If the duration of the current being less than the preset current is greater than the preset duration, the second number of fans to be connected is determined based on the temperature of the battery cell.

[0037] Control the second number of fans to connect to the charging and discharging circuit.

[0038] Furthermore, in the charging and discharging control method for the energy storage device described above, the historical operating information includes the second operating duration of each wind turbine under no surge current conditions;

[0039] Before controlling the second number of fans to connect to the charging and discharging circuit, the following steps are also included:

[0040] The total operating time of each fan is determined based on the duration of absorbing surge current and the second operating time.

[0041] The second number of fans are selected sequentially according to the total operating time from smallest to largest.

[0042] Furthermore, the charging and discharging control method for the energy storage device described above also includes:

[0043] If the second number of fans and the first number of fans have the same Q fans, maintain the state of the switching components corresponding to the Q fans, and control the switching components corresponding to the remaining R fans in the first number of fans to remove the R fans from the charging and discharging circuit.

[0044] If the second number of fans does not have the same fans as the first number of fans, control the switching components corresponding to the first number of fans to remove the first number of fans from the charging and discharging circuit.

[0045] Thirdly, the present invention provides an energy storage system, which includes a power conversion system and an energy storage device as described in any of the preceding claims;

[0046] The power conversion system is electrically connected to the energy storage device;

[0047] The power conversion system is configured to transfer electrical energy from the charging power supply to the energy storage device to charge the energy storage device, or to transfer electrical energy from the energy storage device to the load to discharge the energy storage device.

[0048] The above-described technical solutions of the present invention have at least one or more of the following beneficial effects:

[0049] In implementing the technical solution of this invention, at least one fan is installed in the ventilation duct of the cabinet and connected in series between the battery cell and the power conversion system. In this way, during the charging and discharging process of the battery cell and the power conversion system, the excitation coil of at least one fan can be used as a large inductor to absorb the surge current in the charging and discharging circuit between the two. With the torsional torque of the fan blades, the entire load is superimposed, causing the current in the charging and discharging circuit to rise slowly, realizing soft start of charging and discharging. In addition, the surge current can be converted into mechanical energy, so that the fan blows air into the ventilation duct, reducing the temperature of the battery cell and realizing energy recovery. Attached Figure Description

[0050] The disclosure of this invention will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0051] Figure 1 This is a schematic diagram of the energy storage system according to an embodiment of the present invention;

[0052] Figure 2 This is another structural schematic diagram of the energy storage system according to an embodiment of the present invention;

[0053] Figure 3 This is a flowchart illustrating the control method for energy storage devices. Detailed Implementation

[0054] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0055] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, in this invention, unless otherwise expressly specified and limited, the terms "connected," "linked," etc., should be interpreted broadly. For example, they may refer to a direct connection or an indirect connection through an intermediate medium, or the internal connection of two elements or the interaction between two elements, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0056] Energy storage technology, as an important component of new energy sources, has been widely applied and developed. The safety and efficiency of energy storage devices during charging and discharging are crucial. However, during charging and discharging, the rapid changes in current can generate large surge currents, which can severely impact downstream low-voltage measurement equipment and may even damage it. Furthermore, this surge energy is also wasted.

[0057] Therefore, in order to solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0058] Figure 1 This is a schematic diagram of a structure of an energy storage system according to an embodiment of the present invention, such as... Figure 1 As shown, the energy storage system includes a power conversion system 2 and an energy storage device 1; the power conversion system 2 is electrically connected to the energy storage device 1; wherein, the power conversion system 2 is configured to transmit electrical energy from the charging power supply to the energy storage device 1 to charge the energy storage device 1, or to transmit electrical energy from the energy storage device 1 to a load to discharge the energy storage device 1.

[0059] like Figure 1As shown, the energy storage device 1 in this energy storage system includes a cabinet 11, a battery cell 12, and at least one fan 13. The cabinet 11 includes a chamber 111 and a ventilation duct 112. The ventilation duct 112 is located on both sides of the chamber 111, the battery cell 12 is located inside the chamber 111, and at least one fan 13 is located inside the ventilation duct 112, and the at least one fan 13 is connected in series between the battery cell 12 and the power conversion system 2. The at least one fan 13 can be a DC fan 13.

[0060] See also Figure 1 , Figure 1 Taking two fans 13 as an example, one end of each fan 13 is connected to the power conversion system 2, and the other end is connected to the battery cell 12. Thus, the power conversion system 2, fan 13, battery cell 12, and fan 13 form a series circuit. When the power supply charges the battery cell 12 through the power conversion system 2, or when the battery cell 12 discharges to the load through the power conversion system 2, if the current between the power conversion system 2 and the battery cell 12 exceeds a preset current, a surge current is generated between them. However, since the fan 13 is connected in series in the charging and discharging circuit, and the excitation coil of the DC motor in the fan 13 has a large inductance, the excitation coil of the DC motor can absorb the surge current, thereby suppressing the surge current between the power conversion system 2 and the battery cell 12 and protecting the charging and discharging of the energy storage device 1.

[0061] At the same time, the fan 13 is powered on and started. The mechanical load is converted into an electrical load through the torque of the fan blades in the fan 13. When the fan blades rotate, the angular velocity gradually accelerates from zero. In this way, the current of the DC motor cannot increase sharply in a short time because of the large work load, which is equivalent to realizing the slow rise of the current, thereby realizing the soft start of the charging and discharging process of the energy storage device 1.

[0062] In addition, since the fan 13 is located in the ventilation duct 112, the air delivered by the fan blades flows in the ventilation duct 112, which dissipates heat from the battery cell 12 in the chamber 111, preventing the battery cell 12 from overheating. In this way, no additional inductor is needed, the overall system loss is relatively low, and surge current can also be reused to realize surge current recovery and save energy.

[0063] Figure 2 This is another structural schematic diagram of the energy storage system according to an embodiment of the present invention, such as... Figure 2As shown, the energy storage device 1 contains multiple fans 13. The energy storage device 1 also includes a current acquisition device (not shown in the figure), a temperature acquisition device (not shown in the figure), a controller (not shown in the figure), and a switch assembly 14 corresponding to each of the N fans 13. The switch assembly 14 is connected to its corresponding fan 13 and is used to connect or remove the corresponding fan 13 from the charging / discharging circuit. The controller is electrically connected to the switch assembly 14, the current acquisition device, and the temperature acquisition device. The switch assembly 14 can be two parallel single-pole single-throw switches or a single-pole double-throw switch. The current acquisition device can be a current transformer, and the temperature acquisition device can be a temperature sensor.

[0064] In one specific implementation, the current acquisition device is configured to acquire the current of the charging and discharging circuit, and the temperature acquisition device is configured to acquire the temperature of the battery cell 12. The controller is configured to perform the following steps:

[0065] Figure 3 This is a flowchart illustrating the charging and discharging control method for an energy storage device. This method is implemented by a controller within the energy storage device 1. Figure 3 As shown, the charging and discharging control method of this energy storage device may include the following steps:

[0066] Step 300: Obtain the current of the charging and discharging circuit and the temperature of the battery cell 12 in the energy storage device, and detect whether the current of the charging and discharging circuit is greater than the preset current; if yes, proceed to step 301; if no, proceed to step 305.

[0067] Step 301: Determine the first number of fans 13 to be connected based on the current of the charging and discharging circuit and the temperature of the battery cell 12;

[0068] In a specific implementation, if the current in the charging and discharging circuit is greater than the preset current, it indicates that a surge current has been generated in the charging and discharging circuit. At this time, it is necessary to use the fan 13 to absorb the surge current. However, the surge current generated each time may be different. If a large number of fans 13 are connected, it will cause a large load on the return charge and discharge, which will not be utilized for the charging and discharging of the energy storage device 1. If a small number of fans 13 are connected, the surge current absorption effect will be poor. In addition, the required ventilation volume of the battery cell 12 is also different at different temperatures. Therefore, when a surge current occurs in the charging and discharging circuit, a relatively balanced number of fans 13 can be determined by combining the current in the charging and discharging circuit and the temperature of the battery cell 12, so as to simultaneously meet the requirements of surge absorption effect, small load, and heat dissipation effect.

[0069] Specifically, one implementation is as follows, but the present invention is not limited to the following method: First, the number of fans 13 required to absorb surge current can be determined, denoted as m1. Then, it is determined whether the number of fans 13 can meet the heat dissipation requirements of the battery cell 12. If it can, the first number of fans 13 is determined as m1. If it cannot meet the heat dissipation effect of the battery cell 12, the number of fans 13 that meet the heat dissipation requirements can be obtained by looking up a table or other means, denoted as m2. The first number of fans 13 is determined as m2.

[0070] Step 302: Determine the start-up probability of each wind turbine 13 based on its historical operating information;

[0071] In a specific implementation process, the larger the surge current, the greater the damage to the wind turbine 13 when absorbing the surge current. If a surge current is generated in the charging and discharging circuit, some wind turbines 13 are always connected to absorb the surge current, while others are connected relatively less often. This will result in different lifespans for all wind turbines 13, and the entire energy storage device 1 will fail relatively early, affecting users' evaluation of the energy storage device 1.

[0072] Therefore, in order to solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0073] Specifically, the energy storage device 1 also includes a memory electrically connected to the controller, which stores historical operating information for each wind turbine 13. This historical operating information may include the first operating duration of each wind turbine 13 under different surge currents. That is, after each surge current occurs, the following is recorded: the start-up time of each wind turbine 13 that needs to be started, and the time when the surge current is completely absorbed. The time interval between these two times is the first operating duration of the wind turbine 13 that needs to be started under that surge current. For each wind turbine 13, the memory stores its own first operating duration under different surge currents. For example, wind turbine 131 under surge current I... 11 It ran for 10μs under surge current I 12 It ran for 15μs under surge current I 1j It ran for 20μs. Fan 132 experienced a surge current I... 21 It ran for 15μs under surge current I 22 It ran for 20μs... under surge current I 2j It ran for 15μs. Examples will not be provided here.

[0074] In a specific implementation, since the larger the surge current, the greater the damage to the wind turbine 13, a corresponding weight can be set for different surge currents, with a larger weight for a larger surge current. Thus, the duration for which each wind turbine 13 absorbs the surge current can be determined based on the first operating time and the weights of different surge currents, and the start-up probability can be determined based on the duration of surge current absorption.

[0075] In other words, instead of simply summing up the surge absorption times of all wind turbines 13, the corresponding first operating time is adjusted based on the surge current weight. These adjusted first operating times are then summed to obtain the surge current absorption time for each wind turbine 13, and the start-up probability of each wind turbine 13 is then determined. A longer surge current absorption time results in a lower start-up probability. Thus, for a wind turbine 13, even with a shorter operating time, its larger surge current absorption time will be appropriately extended. Conversely, for another wind turbine 13, although its operating time is longer, its smaller surge current absorption time will be appropriately shortened. This makes the start-up probability of the two wind turbines 13 more reasonable, ultimately ensuring that the damage level of all wind turbines 13 tends to be consistent, i.e., ensuring that the lifespan of all wind turbines 13 tends to be consistent.

[0076] Step 303: Select the first number of fans 13 according to the order of starting probability from large to small;

[0077] Step 304: Control the first number of fans to connect to the charging and discharging circuit;

[0078] After selecting a first number of fans 13 in descending order of their start-up probability, the corresponding switch assembly 14 of the first number of fans 13 is controlled to connect the first number of fans 13 to the charging and discharging circuit, thereby starting the first number of fans to absorb surge current and dissipate heat from the battery cells, while the other fans 13 are not connected to the charging and discharging circuit.

[0079] Step 305: Determine the third number of fans 13 to be connected based on the temperature of the battery cell 12;

[0080] In a specific implementation process, if the current in the charging and discharging circuit is less than or equal to the preset current, it means that there is no surge current in the charging and discharging circuit. In this case, the number of fans 13 that need to be connected can be determined solely based on the temperature of the battery cell 12.

[0081] Step 306: Control the switching assembly 14 corresponding to the third number of fans 13 to connect the third number of fans 13 to the charging and discharging circuit.

[0082] In a specific implementation process, the historical operating information stored in the memory may also include the second operating time of each wind turbine 13 under no surge current. The total operating time of each wind turbine 13 can be determined based on the duration of absorbing surge current and the second operating time. Then, in order of increasing total operating time of each wind turbine 13, a third number of wind turbines 13 are selected and connected to the charging and discharging circuit.

[0083] It should be noted that when selecting the first number of wind turbines 13, the reason for using the surge absorption duration rather than each wind turbine 13 as the selection criterion was because surge current causes relatively greater damage to wind turbines 13, while the damage to wind turbines 13 is relatively smaller when there is no surge current. However, when selecting the third number of wind turbines 13 under the condition of no surge current, it is necessary to combine the surge absorption duration and the second operating duration of each wind turbine 13 under the condition of no surge current to ensure that the total operating duration of each wind turbine 13 is consistent.

[0084] In this embodiment, the energy storage device 1 uses a controller to rationally select which wind turbine 13 to connect when there is a surge current and when there is no surge current, so that the degree of damage to all wind turbines 13 tends to be consistent over time, thereby making the service life of all wind turbines 13 tend to be consistent.

[0085] In a specific implementation process, after the first number of fans 13 are connected to the charging and discharging circuit to absorb the surge current, the number of fans 13 required by the energy storage device 1 may change as the surge current disappears. Therefore, after connecting the first number of fans 13 to the charging and discharging circuit, the following steps can also be performed:

[0086] If the duration of the current being less than the preset current is greater than the preset duration, based on the temperature of the battery cell 12, a second number of fans 13 need to be connected; the switching components 14 corresponding to the second number of fans 13 are controlled to connect the second number of fans 13 to the charging and discharging circuit. The method for determining the second number of fans 13 is the same as the method for determining the third number of fans 13, and will not be repeated here. That is, once the charging and discharging current stabilizes, the control process for connecting the fans 13 can be executed under conditions of no inrush current. However, since the first number of fans 13 has already been connected, the second number of fans 13 can be connected as follows:

[0087] First, if the second number of fans 13 and the first number of fans 13 have the same Q fans 13, maintain the state of the switching components 14 corresponding to the Q fans 13, and control the switching components 14 corresponding to the remaining R fans 13 in the first number of fans 13 to remove the R fans 13 from the charging and discharging circuit. That is, retain the Q fans 13 that have been started, reselect S fans 13 from the fans 13 that have not been started, and connect the remaining R fans 13 from the M fans 13. In this way, we can ensure that each fan 13 can be started as much as possible, and ultimately ensure that the service life of all fans 13 tends to be consistent.

[0088] Second, if there is no identical fan 13 among the second number of fans 13 and the first number of fans 13, control the switching components 14 corresponding to the M fans 13 to remove the M fans 13 from the charging and discharging circuit.

[0089] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effect of this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of this application.

[0090] Those skilled in the art will understand that all or part of the processes in the method of the above-described embodiment can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0091] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An energy storage device, characterized in that, include: The cabinet includes a chamber and a ventilation duct; The battery cell is located within the cavity; At least one fan is located within the ventilation duct; wherein the at least one fan is connected in series between the battery cell and the power conversion system, and the at least one fan is used to absorb the surge current in the charging and discharging circuit between the battery cell and the power conversion system during the charging and discharging process, and to supply air to the ventilation duct to reduce the temperature of the battery cell, wherein the surge current is the current when the current in the charging and discharging circuit is greater than a preset current; A switching assembly corresponding to each of the multiple wind turbines, the switching assembly being used to connect or remove the respective wind turbine from the charging and discharging circuit; A current acquisition device is configured to acquire the current of the charging and discharging circuit; A temperature acquisition device is configured to acquire the temperature of the battery cell; A memory is used to store the historical operating information of each wind turbine; The controller is electrically connected to the memory, the switching assembly, the current acquisition device, and the temperature acquisition device, and is configured to: If the current in the charging / discharging circuit is greater than the preset current, the first number of fans to be connected is determined based on the current in the charging / discharging circuit and the temperature of the battery cell. Based on the historical operating information, the start-up probability of each wind turbine is determined. Select the first number of fans according to the order of their activation probabilities from highest to lowest. Control the switching components corresponding to the first number of fans to connect the first number of fans to the charging and discharging circuit.

2. The energy storage device according to claim 1, characterized in that, The ventilation ducts are located on both sides of the chamber.

3. The energy storage device according to claim 1, characterized in that, All of the fans mentioned are DC fans.

4. A charging and discharging control method for an energy storage device according to any one of claims 1 to 3, characterized in that, If the energy storage device contains multiple fans, the method includes: The current of the charging and discharging circuit and the temperature of the battery cell in the energy storage device are obtained; wherein, the charging and discharging circuit is the circuit between the battery cell and the power conversion system; If the current in the charging and discharging circuit is greater than the preset current, the first number of fans to be connected is determined based on the current in the charging and discharging circuit and the temperature of the battery cell. The start-up probability of each wind turbine is determined based on the historical operating information of each wind turbine among multiple wind turbines; Select the first number of fans in descending order of their activation probability; Control the first number of fans to connect to the charging and discharging circuit.

5. The charging and discharging control method for an energy storage device according to claim 4, characterized in that, The historical operation information includes the first operating duration of each wind turbine under different surge currents each time: Based on the historical operating information of each of the plurality of wind turbines, the start-up probability of each wind turbine is determined, including: The duration for each wind turbine to absorb surge current is determined based on the first operating time and the weights of different surge currents. The activation probability is determined based on the duration of the surge current absorption.

6. The charging and discharging control method for an energy storage device according to claim 5, characterized in that, Also includes: If the duration of the current in the charging and discharging circuit being less than the preset current is greater than the preset duration, the second number of fans to be connected is determined based on the temperature of the battery cell. Control the second number of fans to connect to the charging and discharging circuit.

7. The charging and discharging control method for an energy storage device according to claim 6, characterized in that, The historical operation information also includes the second operating time of each wind turbine under no surge current; Before controlling the second number of fans to connect to the charging and discharging circuit, the following steps are also included: The total operating time of each fan is determined based on the duration of absorbing surge current and the second operating time. The second number of fans are selected sequentially according to the total operating time from smallest to largest.

8. The charging and discharging control method for an energy storage device according to claim 7, characterized in that, Also includes: If the second number of fans and the first number of fans have the same Q fans, maintain the state of the switching components corresponding to the Q fans, and control the switching components corresponding to the remaining R fans in the first number of fans to remove the R fans from the charging and discharging circuit. If the second number of fans does not have the same fans as the first number of fans, control the switching components corresponding to the first number of fans to remove the first number of fans from the charging and discharging circuit.

9. An energy storage system, characterized in that, Includes a power conversion system and an energy storage device as described in any one of claims 1 to 3; The power conversion system is electrically connected to the energy storage device; The power conversion system is configured to transfer electrical energy from the charging power supply to the energy storage device to charge the energy storage device, or to transfer electrical energy from the energy storage device to the load to discharge the energy storage device.

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