Energy storage equipment, charging and discharging control method thereof and energy storage system

Abstract

The invention provides energy storage equipment, a charging and discharging control method thereof and an energy storage system. The energy storage equipment comprises a cabinet body with a cavity and a ventilation air duct, a battery cell located in the cavity and at least one draught fan located in the ventilation air 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 for absorbing surge current in a charging and discharging loop between the battery cell and the power conversion system by using a magnet exciting coil of the at least one fan as a large inductor in the charging and discharging process of the battery cell and the power conversion system; and air is supplied to the ventilation air duct, so that the temperature of the battery cell is reduced, and energy recovery is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of battery energy storage systems, and in particular to an energy storage device and a charge and discharge control method thereof, and an energy storage system. Background Art

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

[0003] The safety and efficiency of energy storage equipment during charging and discharging are crucial. However, during the charging and discharging process, due to the rapid change of current, large surge current may be generated, which will inevitably have a serious impact on the low-voltage measurement equipment at the back end, and may even cause damage to the back-end equipment. At the same time, these surge energies will also be 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 needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] In order to overcome the above-mentioned defects, the present 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 has a serious impact on the low-voltage measuring equipment at the back end and the energy loss is large during the charging and discharging process of the energy storage device.

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

[0007] A cabinet body, the cabinet body comprising a chamber and a ventilation duct;

[0008] A battery cell, located in the chamber;

[0009] at least one fan located in the ventilation duct;

[0010] Among them, 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 of the battery cell and the power conversion system, and to supply air to the ventilation duct to reduce the temperature of the battery cell. The surge current is the current when the current of the charging and discharging circuit is greater than the 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 switch assembly corresponding to each of the plurality of fans, the switch assembly being used to connect or remove the corresponding fan from the charge-discharge circuit;

[0014] A current collection device, configured to collect the current of the charging and discharging circuit;

[0015] A temperature collection device, configured to collect the temperature of the battery cell;

[0016] The controller is electrically connected to the switch component, the current collection device and the temperature collection device, and is configured to determine a first number of fans that need to be connected based on the current of the charge and discharge circuit and the temperature of the battery cell if the current of the charge and discharge circuit is greater than a preset current, and control the switch components corresponding to the first number of fans to connect the first number of fans to the charge and discharge circuit.

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

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

[0019] The controller is also configured to:

[0020] Determining the startup probability of each wind turbine according to the historical operation information;

[0021] The first number of wind turbines is selected in descending order of the startup 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, the at least one fan is a DC fan.

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

[0025] If there are multiple motors in the energy storage device, obtain the current of the charge-discharge circuit and the temperature of the battery cell in the energy storage device; wherein the charge-discharge circuit is a circuit between the battery cell and the power conversion system;

[0026] If the current of the charging and discharging circuit is greater than a preset current, determining a first number of fans that need to be connected according to the current of the charging and discharging circuit and the temperature of the battery cell;

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

[0028] Furthermore, in the above-mentioned method for controlling the charge and discharge of the energy storage device, before controlling the first number of wind turbines to be connected to the charge and discharge circuit, the method further includes:

[0029] Determining a startup probability of each wind turbine according to historical operation information of each wind turbine among the plurality of wind turbines;

[0030] The first number of fans are selected in descending order of startup probability.

[0031] Furthermore, in the above-mentioned charge and discharge control method for energy storage equipment, the historical operation information includes the first operation duration of each wind turbine under different surge currents each time:

[0032] Determining the startup probability of each wind turbine according to the historical operation information of each wind turbine among the plurality of wind turbines includes:

[0033] Determining the duration for each wind turbine to absorb the surge current according to the first operating duration and the weights of different surge currents;

[0034] The startup probability is determined according to the duration of absorbing the surge current.

[0035] Furthermore, the above-mentioned charge and discharge control method of the energy storage device further includes:

[0036] If the duration for which the current is less than the preset current is longer than the preset duration, determining a second number of fans that need to be connected according to the temperature of the battery cell;

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

[0038] Further, in the above-mentioned charge and discharge control method of the energy storage device, the historical operation information includes the second operation time of each wind turbine without surge current;

[0039] Before controlling the second number of fans to be connected to the charging and discharging circuit, the method further includes:

[0040] Determining the total operation time of each wind turbine according to the duration of absorbing the surge current and the second operation time;

[0041] The second number of fans are selected in order of total operating time from small to large.

[0042] Furthermore, the above-mentioned charge and discharge control method of the energy storage device further includes:

[0043] If the second number of fans and the first number of fans have the same Q fans, maintain the states of the switch components corresponding to the Q fans, and control the switch 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 contain the same fan as the first number of fans, the switch components corresponding to the first number of fans are controlled to remove the first number of fans from the charging and discharging circuit.

[0045] In a third aspect, the present invention provides an energy storage system, the energy storage system comprising a power conversion system and an energy storage device as described in any one of the above items;

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

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

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

[0049] In the process of implementing the technical solution of the present invention, at least one fan is set in the ventilation duct in the cabinet, and at least one fan is 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 inductance to absorb the surge current in the charging and discharging circuit between the two, and cooperate with the torsional torque of the fan blades in the fan to superimpose the entire load, so that the current in the charging and discharging circuit rises slowly, realizing soft start of charging and discharging, and can also convert the surge current into mechanical energy, so that the fan supplies air to the ventilation duct, reduces the temperature of the battery cell, and realizes energy recovery. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0053] Figure 3 It is a flow chart of a control method of an energy storage device. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0055] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, in the present invention, unless otherwise clearly specified and defined, the terms "connected", "connected", and the like should be understood in a broad sense. For example, it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0056] As an important component of new energy, energy storage technology has been widely used and developed. Among them, the safety and efficiency of energy storage equipment during charging and discharging are crucial. However, during the charging and discharging process of energy storage equipment, due to the rapid change of current, large surge current may be generated, which will inevitably have a serious impact on the low-voltage measurement equipment at the back end, and may even cause damage to the back-end equipment. At the same time, these surge energies will also be wasted.

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

[0058] Figure 1 is a schematic diagram of a structure of an energy storage system according to an embodiment of the present invention. 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 the electric energy of the charging power supply to the energy storage device 1 to charge the energy storage device 1, or to transmit the electric energy of the energy storage device 1 to the load to discharge the energy storage device 1.

[0059] like Figure 1As shown, the energy storage device 1 in the 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 in the chamber 111, and at least one fan 13 is located in the ventilation duct 112, and at least one fan 13 is connected in series between the battery cell 12 and the power conversion system 2. At least one fan 13 can be a DC fan 13.

[0060] Continue to see Figure 1 , Figure 1 In the example, two fans 13 are used for explanation, wherein one end of each fan 13 is connected to the power conversion system 2, and the other end of the fan 13 is connected to the battery cell 12, so that the power conversion system 2, the fan 13, the battery cell 12, and the 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 is greater than the preset current, a surge current is generated between the power conversion system 2 and the battery cell 12. However, since the fan 13 is connected in series in the charging and discharging circuit, the excitation coil of the DC motor in the fan 13 itself has a large inductance, so that 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, and the mechanical load is converted into an electrical work load through the torque of the fan blades in the fan 13. When the torque of the fan blades rotates, the angular velocity gradually accelerates from zero. In this way, the current of the DC motor cannot increase sharply in a short time due to the large work load, which is equivalent to achieving a slow increase in current, thereby achieving a 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 wind sent out by the fan blades flows in the ventilation duct 112, dissipating the heat of the battery cells 12 in the chamber 111, thereby preventing the battery cells 12 from overheating. In this way, there is no need to add additional inductance, the loss of the entire system is relatively low, and the surge current can be reused to achieve surge current recovery and save energy.

[0063] Figure 2 is another structural schematic diagram of the energy storage system according to an embodiment of the present invention, such as Figure 2As shown, the total number of fans 13 in the energy storage device 1 is multiple. The energy storage device 1 also includes a current acquisition device (no longer shown in the figure), a temperature acquisition device (no longer shown in the figure), a controller (no longer shown in the figure) and a switch assembly 14 corresponding to each fan 13 of the N fans 13. Among them, the switch assembly 14 is connected to the corresponding fan 13, and the switch assembly 14 is used to connect or remove the corresponding fan 13 to the charging and 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 single-pole single-throw switches in parallel, 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 a specific implementation process, the current acquisition device is configured to acquire the current of the charge and discharge 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 is a flow chart of a method for controlling the charge and discharge of an energy storage device, wherein the method for controlling the charge and discharge is implemented by a controller in the energy storage device 1, such as Figure 3 As shown, the charge and discharge control method of the energy storage device may include the following steps:

[0066] Step 300, obtaining the current of the charge-discharge circuit and the temperature of the battery cell 12 in the energy storage device, and detecting whether the current of the charge-discharge circuit is greater than a preset current; if so, executing step 301, if not, executing step 305;

[0067] Step 301, determining a first number of fans 13 that need to be connected according to the current of the charge-discharge circuit and the temperature of the battery cell 12;

[0068] In a specific implementation process, if the current of the charging and discharging circuit is greater than the preset current, it means that a surge current is generated in the charging and discharging circuit. At this time, the fan 13 is needed to absorb the surge current. However, the surge current generated each time may also be different. If a large number of fans 13 are connected, it will cause a large load during charging and discharging, and the charging and discharging of the energy storage device 1 will not be utilized. If a small number of fans 13 are connected, the surge current absorption effect is poor. In addition, the ventilation volume required by the battery cell 12 is different at different temperatures. Therefore, when a surge current appears in the charging and discharging circuit, a relatively balanced number of fans 13 can be determined in combination with the current of the charging and discharging circuit and the temperature of the battery cell 12 to connect the fan 13, that is, it can simultaneously meet the surge absorption effect, small load, and heat dissipation effect.

[0069] Specifically, one implementation method is as follows, but the present invention is not limited to the following method: the number of fans 13 required to absorb surge current can be determined first, recorded as m1, and then it is judged whether the number of fans 13 can meet the heat dissipation requirements of the battery cells 12. If so, the first number of fans 13 determined is m1. If the heat dissipation effect of the battery cells 12 cannot be met, the number of fans 13 that meet the heat dissipation requirements can be obtained by looking up a table or the like, recorded as m2, and the first number of fans 13 determined is m2.

[0070] Step 302: Determine the startup probability of each wind turbine 13 according to the historical operation information of each wind turbine 13;

[0071] In a specific implementation process, the larger the surge current, the greater the damage to the fan 13 when it absorbs the surge current. If a surge current is generated in the charging and discharging circuit, some of the multiple fans 13 are always connected to absorb the surge current, while other fans 13 are connected relatively less frequently. This will result in different lifespans for all fans 13, and the entire energy storage device 1 will fail relatively early, affecting the user's evaluation of the energy storage device 1.

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

[0073] Specifically, the energy storage device 1 also includes a memory, which is electrically connected to the controller, and the memory stores the historical operation information of each fan 13. Among them, the historical operation information may include the first operating time of each fan 13 under different surge currents each time. That is to say, each time a surge current is generated, the following records will be made: the start time of each fan 13 that needs to be started, and the time when the surge current is completely absorbed. In this way, the time period between the two moments is the first operating time of the fan 13 that needs to be started under the surge current. For each fan 13, the memory stores the first operating time of each fan 13 under different surge currents each time. For example, fan 131 is at a surge current I 11 The surge current I 12 It ran for 15μs under the surge current. 1j The fan 132 operates for 20μs at the surge current I 21 The surge current I 22 It ran for 20μs under the surge current I 2j The operation lasted for 15 μs. We will not give examples here.

[0074] In a specific implementation process, since the larger the surge current, the greater the damage to the fan 13, corresponding weights can be set for different surge currents, and the larger the surge current, the greater the weight. In this way, the duration of each fan 13 absorbing the surge current can be determined based on the first operating time and the weights of different surge currents, and the startup probability can be determined based on the duration of absorbing the surge current.

[0075] That is to say, all the surge absorbing operation times of a certain fan 13 are no longer simply superimposed, but the corresponding first operation time is adjusted in combination with the weight of the surge current, and then the adjusted first operation time is superimposed to obtain the time for each fan 13 to absorb the surge current, and then the start probability of each fan 13 is determined. Among them, the longer the time for absorbing the surge current, the smaller the start probability. In this way, for a certain fan 13, although the operation time is short, due to the large surge current it absorbs, the final time for absorbing the surge current will be appropriately extended. For another fan 13, although the operation time is long, due to the small surge current it absorbs, the final time for absorbing the surge current will be appropriately shortened. In this way, the probability of the two fans 13 being started is more reasonable, and finally the degree of damage of all fans 13 is guaranteed to be consistent, that is, the life of all fans 13 is guaranteed to be consistent.

[0076] Step 303, selecting the first number of wind turbines 13 in descending order of the startup probability;

[0077] Step 304, controlling the first number of fans to be connected to the charging and discharging circuit;

[0078] After selecting the first number of fans 13 in order of the probability of starting each fan 13 from large to small, the switch components 14 corresponding to the first number of fans 13 are controlled to connect the first number of fans 13 to the charging and discharging circuit to start the first number of fans to absorb surge current and dissipate heat for the battery cells, while other fans 13 are not connected for charging and discharging.

[0079] Step 305: Determine the third number of fans 13 that need to be connected according to the temperature of the battery core 12;

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

[0081] Step 306: Control the switch components 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 operation information stored in the memory may also include the second operating time of each fan 13 without surge current. The total operating time of each fan 13 can be determined based on the duration of absorbing surge current and the second operating time. After selecting a third number of fans 13 in order of the total operating time of each fan 13 from small to large, the third number of fans 13 are connected to the charging and discharging circuit.

[0083] It should be noted that when the first number of fans 13 are selected above, the reason why the duration of absorbing surges rather than each fan 13 is used as the selection criterion is because the surge current causes relatively greater damage to the fan 13, while when there is no surge current, the damage to the fan 13 during operation is relatively small. However, when the third number of fans 13 is selected without surge current, it is necessary to combine the duration of absorbing surge current and the second operating time of each fan 13 without surge current at the same time, so as to ensure that the total operating time of each fan 13 tends to be consistent as a whole.

[0084] The energy storage device 1 of this embodiment uses a controller to reasonably select the connected fans 13 when there is a surge current and when there is no surge current, so that the degree of damage of all the fans 13 tends to be consistent with the passage of time, thereby making the service life of all the fans 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, as the surge current disappears, the number of fans 13 required by the energy storage device 1 may change. Therefore, after the first number of fans 13 are connected to the charging and discharging circuit, the following steps may also be performed:

[0086] If the time length during which the current is less than the preset current is longer than the preset time length, the second number of fans 13 that need to be connected is determined according to the temperature of the battery cell 12; the switch 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. Among them, the method for determining the second number of fans 13 is the same as the method for determining the third number of fans 13 mentioned above, and will not be repeated here. In other words, as the charging and discharging current stabilizes, the control process of connecting the fans 13 without surge current can be executed. However, since the first number of fans 13 have 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, the states of the switch components 14 corresponding to the Q fans 13 are maintained, and the switch components 14 corresponding to the remaining R fans 13 in the first number of fans 13 are controlled to remove the R fans 13 from the charging and discharging circuit. In other words, the Q fans 13 that have been started are retained, and S fans 13 are reselected from the fans 13 that have not been started, and the remaining R fans 13 in the M fans 13 are connected, so that each fan 13 can be started as much as possible, and finally the service life of all fans 13 is ensured to be consistent.

[0088] Second, if the second number of fans 13 and the first number of fans 13 do not have the same fan 13, control the switch components 14 corresponding to the M fans 13 to remove the M fans 13 from the charging and discharging circuit.

[0089] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effect of the present application, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders. These changes are within the scope of protection of the present application.

[0090] It is understood by those skilled in the art that all or part of the processes in the method for implementing the above-mentioned embodiment of the present application can also be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of each of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device, medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electric carrier signal, telecommunication signal and software distribution medium that can carry the computer program code. It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media do not include electric carrier signals and telecommunication signals.

[0091] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle 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 these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An energy storage device, characterized in that: include: A cabinet body, the cabinet body comprising a chamber and a ventilation duct; A battery cell, located in the chamber; at least one fan located in the ventilation duct; Among them, 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 of the battery cell and the power conversion system, and to supply air to the ventilation duct to reduce the temperature of the battery cell. The surge current is the current when the current of the charging and discharging circuit is greater than the preset current.

2. The energy storage device according to claim 1, characterized in that: The total number of fans is multiple; The energy storage device also includes: A switch assembly corresponding to each of the plurality of fans, the switch assembly being used to connect or remove the corresponding fan from the charge-discharge circuit; A current collection device, configured to collect the current of the charging and discharging circuit; A temperature collection device, configured to collect the temperature of the battery cell; The controller is electrically connected to the switch component, the current collection device and the temperature collection device, and is configured to determine a first number of fans that need to be connected based on the current of the charge and discharge circuit and the temperature of the battery cell if the current of the charge and discharge circuit is greater than a preset current, and control the switch components corresponding to the first number of fans to connect the first number of fans to the charge and discharge circuit.

3. The energy storage device according to claim 2, characterized in that: Also includes: A memory, electrically connected to the controller, and used to store historical operation information of each wind turbine; The controller is also configured to: Determining the startup probability of each wind turbine according to the historical operation information; The first number of wind turbines is selected in descending order of the startup probabilities.

4. The energy storage device according to any one of claims 1 to 3, characterized in that: The ventilation ducts are located on both sides of the chamber.

5. The energy storage device according to any one of claims 1 to 3, characterized in that: The at least one fan is a DC fan.

6. A charge and discharge control method for an energy storage device according to any one of claims 1 to 5, characterized in that: include: If there are multiple motors in the energy storage device, obtain the current of the charge-discharge circuit and the temperature of the battery cell in the energy storage device; wherein the charge-discharge circuit is a circuit between the battery cell and the power conversion system; If the current of the charging and discharging circuit is greater than a preset current, determining a first number of fans that need to be connected according to the current of the charging and discharging circuit and the temperature of the battery cell; Control the first number of fans to be connected to the charging and discharging circuit.

7. The charge and discharge control method of the energy storage device according to claim 5, characterized in that: Before controlling the first number of fans to be connected to the charging and discharging circuit, the method further includes: Determining a startup probability of each wind turbine according to historical operation information of each wind turbine among the plurality of wind turbines; The first number of fans are selected in descending order of startup probability.

8. The charge and discharge control method of the energy storage device according to claim 7, characterized in that: The historical operation information includes the first operation duration of each wind turbine under different surge currents each time: Determining the startup probability of each wind turbine according to the historical operation information of each wind turbine among the plurality of wind turbines includes: Determining the duration for each wind turbine to absorb the surge current according to the first operating duration and the weights of different surge currents; The startup probability is determined according to the duration of absorbing the surge current.

9. The charge and discharge control method of the energy storage device according to claim 7, characterized in that: Also includes: If the duration for which the current is less than the preset current is longer than the preset duration, determining a second number of fans that need to be connected according to the temperature of the battery cell; Control the second number of fans to be connected to the charging and discharging circuit.

10. The charge and discharge control method of the energy storage device according to claim 9, characterized in that: The historical operation information includes the second operation time of each wind turbine without surge current; Before controlling the second number of fans to be connected to the charging and discharging circuit, the method further includes: Determining the total operation time of each wind turbine according to the duration of absorbing the surge current and the second operation time; The second number of fans are selected in order of total operating time from small to large.

11. The charge and discharge control method of the energy storage device according to claim 10, characterized in that: Also includes: If the second number of fans and the first number of fans have the same Q fans, maintain the states of the switch components corresponding to the Q fans, and control the switch 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 contain the same fan as the first number of fans, the switch components corresponding to the first number of fans are controlled to remove the first number of fans from the charging and discharging circuit.

12. An energy storage system, characterized in that: comprising a power conversion system and an energy storage device as claimed in any one of claims 1 to 5; The power conversion system is electrically connected to the energy storage device; The power conversion system is configured to transfer the electric energy of the charging power supply to the energy storage device to charge the energy storage device, or to transfer the electric energy of the energy storage device to a load to discharge the energy storage device.

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