Energy storage system and equipment

Abstract

The utility model discloses an energy storage system and equipment. The energy storage system comprises a first bus, an energy storage inverter, a direct current conversion module, thermal management equipment, a control system and at least one battery module, the energy storage inverter is electrically connected with the battery module and the first bus and used for converting direct current output by the battery module into alternating current and transmitting the alternating current to the first bus and converting the alternating current output by the first bus into direct current to charge the battery module. The direct current conversion module is electrically connected with the energy storage inverter and is used for transmitting the direct current to the thermal management equipment; the heat management equipment is used for executing heating operation or refrigerating operation on the energy storage system; and the control system is electrically connected with the energy storage inverter and is used for controlling the energy storage inverter to enter a black-start mode when the temperature of the energy storage system is within a safe temperature range. According to the technical scheme provided by the utility model, the black start function of the energy storage system in a severe environment can be realized.

Description

Technical Field

[0001] The utility model relates to the technical field of energy storage, and in particular to an energy storage system and equipment. Background Art

[0002] Because the power system lacks the means to effectively store large amounts of electrical energy, power generation, transmission, and distribution must be completed simultaneously. This requires the system to always be in a dynamic balance state. Momentary imbalances may lead to safety and stability issues. Battery energy storage systems, through their rapid response characteristics, can quickly absorb changes in user loads and fundamentally solve the control problems of the power system.

[0003] Current energy storage systems cannot meet the black start function of the energy storage system under long-term standby or off-grid conditions because the battery cell temperature is too high or too low, resulting in the inability to output power through the energy storage inverter. Utility Model Content

[0004] The embodiments of the present invention provide an energy storage system and equipment to realize the black start function of the energy storage system in harsh environments.

[0005] In a first aspect, an embodiment of the present utility model provides an energy storage system, comprising: a first bus, an energy storage inverter, a DC conversion module, a thermal management device, a control system, and at least one battery module;

[0006] The energy storage inverter is electrically connected to the battery module and the first busbar, respectively, and is used to convert the direct current output by the battery module into alternating current and transmit it to the first busbar, and to convert the alternating current output by the first busbar into direct current to charge the battery module;

[0007] The DC conversion module is electrically connected to the energy storage inverter and is used to transmit the DC power to the thermal management device; the thermal management device is used to perform heating or cooling operations on the energy storage system; the control system is electrically connected to the energy storage inverter and is used to control the energy storage inverter to enter a black start mode when the temperature of the energy storage system is within a safe temperature range.

[0008] Optionally, the DC conversion module may include: a first DC conversion unit; the input end of the first DC conversion unit is electrically connected to the energy storage inverter; the output end of the first DC conversion unit is electrically connected to the thermal management device; and the output end of the first DC conversion unit is electrically connected to the control system.

[0009] Optionally, the energy storage system may include: a second DC conversion unit and a third DC conversion unit; the input end of the second DC conversion unit is electrically connected to the energy storage inverter; the output end of the second DC conversion unit is electrically connected to the thermal management device; the input end of the third DC conversion unit is electrically connected to the energy storage inverter; and the output end of the third DC conversion unit is electrically connected to the control system.

[0010] Optionally, the thermal management device may include at least: a heating device and a cooling device; the control system may include at least: a battery management system, an energy management system and an energy storage converter.

[0011] Optionally, the DC conversion module is integrated into the high-voltage box, the thermal management device or the control system.

[0012] Optionally, the energy storage system may further include: a control cabinet, a second busbar and a high-voltage box; the number of the battery modules is multiple; the high-voltage box is electrically connected to the battery modules in a one-to-one correspondence; the control cabinet is electrically connected to the energy storage inverter and the second busbar, respectively, for transmitting the direct current output by the energy storage inverter to the second busbar; the high-voltage box is electrically connected to the second busbar, for transmitting the direct current on the second busbar to the corresponding battery modules.

[0013] Optionally, the DC conversion module may include: a first DC conversion unit; the battery module includes a first battery module and a second battery module; the high-voltage box includes a first high-voltage box and a second high-voltage box; the first high-voltage box is electrically connected to the first battery module; the second high-voltage box is electrically connected to the second battery module; the first high-voltage box is electrically connected to the second high-voltage box through a first switch; the second high-voltage box is electrically connected to the input end of the first DC conversion unit through a second switch; the output end of the first DC conversion unit is electrically connected to the thermal management device through a third switch; and the output end of the first DC conversion unit is electrically connected to the control system through a fourth switch.

[0014] Optionally, the DC conversion module may include: a second DC conversion unit and a third DC conversion unit; the battery module includes a first battery module and a second battery module; the high-voltage box includes a first high-voltage box and a second high-voltage box; the first high-voltage box is electrically connected to the first battery module; the second high-voltage box is electrically connected to the second battery module; the first high-voltage box is electrically connected to the second high-voltage box through a first switch; the second high-voltage box is electrically connected to the input ends of the second DC conversion unit and the third DC conversion unit respectively through a second switch; the output end of the second DC conversion unit is electrically connected to the thermal management device through a third switch; the output end of the third DC conversion unit is electrically connected to the control system through a fourth switch.

[0015] In a second aspect, an embodiment of the present invention provides an energy storage device, including the energy storage system provided by any embodiment of the present invention.

[0016] In the present invention, the energy storage system includes a first busbar, an energy storage inverter, a DC conversion module, a thermal management device, a control system, and at least one battery module. The first busbar is electrically connected to the energy storage inverter, which is electrically connected to the battery modules. The energy storage inverter can convert the DC power output by the battery module into AC power and transmit it to the first busbar, and convert the AC power output by the first busbar into DC power and transmit it to the battery module. The DC conversion module can be connected to the energy storage inverter to transmit the DC power to the thermal management device, so that the thermal management device can heat the entire energy storage system when the temperature exceeds the safe temperature range, so that the battery module will not be unable to output power through the energy storage inverter due to the temperature of the battery cell being too high or too low. In this embodiment, the control system can control the energy storage inverter to enter the black start mode when the temperature of the energy storage system is within the safe temperature range. Therefore, the energy storage system can realize the off-grid operation mode of the energy storage inverter under long-term standby or off-grid conditions and harsh environmental conditions. That is, the battery module is used as the black start power supply to quickly achieve black start, ensure continuous power supply to the power system, and improve the reliability of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of an energy storage system in the prior art;

[0018] Figure 2 A schematic structural diagram of an energy storage system provided in an embodiment of the present utility model;

[0019] Figure 3 A schematic structural diagram of another energy storage system provided in an embodiment of the present utility model;

[0020] Figure 4 A schematic diagram of a black start process of an energy storage system provided in this embodiment;

[0021] Figure 5 A schematic structural diagram of an energy storage device provided in an embodiment of the present utility model. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all of its components.

[0023] Figure 1It is a structural diagram of an energy storage system in the prior art. The first busbar 11' is electrically connected to the battery module 15' through the energy storage inverter PSC', the control cabinet 12' and the high-voltage box 14' in sequence. At present, the energy storage system cannot output power through the energy storage converter under high / low temperature or off-grid conditions because the battery core temperature of the battery module 15' is too high / too low, so the energy storage system cannot meet the black start function under long-term standby or off-grid conditions. In addition, when designing a 100-megawatt energy storage power station, because 400V AC power distribution is required in the energy storage system, an additional 690V / 400V isolation transformer T2' needs to be designed. At the same time, the main transformer T1' also needs to reserve the maximum power of the auxiliary transformer, so the comprehensive cost and floor space of the energy storage power station have no advantages.

[0024] In order to solve the above problems, the present invention provides an energy storage system. Figure 2 As shown, Figure 2 This is a schematic diagram of the structure of an energy storage system provided by an embodiment of the present invention. This embodiment can achieve black start functionality in high / low temperature conditions and off-grid conditions by drawing power from the DC side. It also eliminates the need for isolation transformer T2', reducing the cost and footprint of the energy storage system. Specifically, the energy storage system includes: a first bus 11, an energy storage inverter PSC, a DC conversion module 12, a thermal management device 13, a control system 14, and at least one battery module 15.

[0025] The energy storage inverter PSC is electrically connected to the battery module 15 and the first bus 11, respectively, and is used to convert the direct current output by the battery module 15 into alternating current and transmit it to the first bus 11, and to convert the alternating current output by the first bus 11 into direct current to charge the battery module 15;

[0026] The DC conversion module 12 is electrically connected to the energy storage inverter PSC and is used to transmit DC power to the thermal management device 13; the thermal management device 13 is used to perform heating or cooling operations on the energy storage system; the control system 14 is electrically connected to the energy storage inverter PSC and is used to control the energy storage inverter PSC to enter the black start mode when the temperature of the energy storage system is within the safe temperature range.

[0027] In an embodiment of the present invention, the energy storage system includes a first busbar, an energy storage inverter, a DC conversion module, a thermal management device, a control system, and at least one battery module. The first busbar is electrically connected to the energy storage inverter, and the energy storage inverter is electrically connected to the battery modules respectively. The energy storage inverter can convert the DC power output by the battery module into AC power and transmit it to the first busbar, and convert the AC power output by the first busbar into DC power and transmit it to the battery module. The DC conversion module can be connected to the energy storage inverter to transmit the DC power to the thermal management device, so that the thermal management device can heat the entire energy storage system when the temperature exceeds the safe temperature range, so that the battery module will not be unable to output power through the energy storage inverter due to the temperature of the battery cell being too high or too low. In this embodiment, the control system can control the energy storage inverter to enter the black start mode when the temperature of the energy storage system is within the safe temperature range. Therefore, the energy storage system can realize the off-grid operation mode of the energy storage inverter under long-term standby or off-grid conditions and harsh environmental conditions. That is, the battery module is used as the black start power supply to quickly achieve black start, ensure continuous power supply to the power system, and improve the reliability of the energy storage system.

[0028] The above is the core concept of the present invention. The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0029] As modern society's dependence on electricity supply continues to increase, the consequences of large-scale power outages are becoming increasingly serious. Black start technology is an effective means to reduce the losses caused by large-scale power system failures. Specifically, it can use the units with self-starting capabilities in the power system to start them first, gradually load the load and expand the recovery range of the system, and ultimately achieve the recovery and power supply of the entire power system. However, in extreme environments of high or low temperatures, the battery cells of the battery module 15 of the energy storage system are easily affected and cannot achieve self-starting through the output power of the energy storage converter in the controller system 14. In this embodiment, Figure 2As shown, the energy storage system includes not only a first busbar 11, a power storage inverter PSC, and at least one battery module 15 electrically connected in sequence, but also a DC conversion module 12 and a thermal management device 13. The thermal management device 13 can obtain DC power through the DC conversion module 12 and perform heating or cooling operations to keep the battery module 15 within a safe temperature range. In this embodiment, the safe temperature range can be set according to the performance of the battery cell. If the current temperature affects the output function of the battery module 15, the temperature is not within the safe temperature range and is considered an extreme environment. In this case, the thermal management device 13 restores the temperature of the battery module 15 to the safe temperature range, and then the output power of the battery module 15 is used to achieve a black start of the energy storage system. Specifically, when the energy storage system is in the energy storage working state, the energy storage inverter PSC converts the AC power output by the first busbar 11 into DC power to charge the battery module 15; when the energy storage system is in the power supply working state, the energy storage inverter PSC converts the DC power output by the battery module 15 into AC power and transmits it to the first busbar 11. The thermal management device 13 can detect the ambient temperature of the energy storage system. When the energy storage system is in a low temperature / high temperature operating condition for a long time (not within the safe temperature range), the thermal management device 13 can obtain DC power from the first bus 11 through the DC conversion module 12 and the energy storage inverter PSC, and heat or cool the energy storage system until the temperature returns to a safe temperature range. Optionally, the thermal management device 13 may include at least: a heating device and a cooling device to achieve heating and cooling functions. In addition, the thermal management device 13 may also include a DC device or an AC device, which is not specifically limited in this embodiment. When the energy storage system returns to a safe temperature range, the control system 14 can perform a power outage detection on the power grid system, and when the grid power is detected, it sends an off-grid working mode instruction to the energy storage inverter PSC to achieve a black start. Specifically, the control system 14 may include at least: a battery management system, an energy management system, and an energy storage converter. The energy management system can detect grid power outages. When the grid power is detected, the energy management system issues an off-grid operating mode instruction to the energy storage inverter (PSC) and simultaneously issues a high-voltage start-up and close-down instruction to the battery management system (BMS), thereby achieving a black start using the battery module 15 as the power source. That is, the battery module 15 outputs voltage to the first bus 11 through the energy storage inverter (PSC) for use by other loads on the first bus 11. The control system 14 also obtains DC power from the first bus 11 through the DC conversion module 12 and the energy storage inverter (PSC) to obtain operating power.

[0030] When the ambient temperature of the energy storage system is within a safe temperature range, the DC conversion module 12 is electrically connected to the energy storage inverter PSC to obtain DC power through the first bus 11 and transmit the DC power to the control system 14. Similarly, the energy management system can perform grid power outage detection. When the grid power is detected, the energy management system issues an off-grid operating mode instruction to the energy storage inverter PSC and simultaneously issues a high-voltage start-up and close-down instruction to the battery management system BMS, achieving a black start using the battery module 15 as the power source. This embodiment effectively solves the problem of the energy storage system being unable to achieve self-starting in extreme environments such as high or low temperatures, further improving the reliability of the energy storage system.

[0031] Continue to refer Figure 2 Optionally, the energy storage system may further include: a control cabinet 16, a second busbar 17, and a high-voltage box 18; the number of battery modules 15 is multiple; the high-voltage box 18 is electrically connected to the battery modules 15 in a one-to-one correspondence; the control cabinet 16 is electrically connected to the energy storage inverter PSC and the second busbar 17 respectively, for transmitting the DC power output by the energy storage inverter PSC to the second busbar 17; the high-voltage box 18 is electrically connected to the second busbar 17, for transmitting the DC power on the second busbar 17 to the corresponding battery module 15. The control cabinet 16 is used to connect the energy storage inverter PSC and the second busbar 17 to establish a safe connection between the power grid system and the energy storage system, optionally, as Figure 2 As shown, the switch element QS in the control cabinet 16 is used to connect the energy storage inverter PSC to the second busbar 17. The grid-connected and off-grid states are achieved by controlling the switch element QS. Furthermore, the control cabinet 16 may also include circuit breakers FU1 and FU2, which are used to disconnect the circuit when the current exceeds a specified value to prevent damage to equipment or circuits due to overload. Circuit breaker FU2 can be grounded via fuse F. Fuse F is an overload protection device primarily used for short circuit and overcurrent protection. There can be multiple high-voltage boxes 18 and multiple battery modules 15. The high-voltage boxes 18 are electrically connected to each battery module 15 in a one-to-one correspondence. Each high-voltage box 18 is also electrically connected to the second busbar 17. The control system 14 can control the switch QF and AC contactors KM1 and KM2 to transmit DC power between the second busbar 17 and the battery modules 15. Furthermore, the high-voltage box 18 may also include a circuit breaker FU to protect the battery modules 15.

[0032] Optionally, the DC conversion module 12 can be integrated into the high voltage box 18, the thermal management device 13 or the control system 14. In this embodiment, the DC conversion module 12 for obtaining DC power for the thermal management device 13 and the control system 14 can be set separately, such as Figure 2 As shown, it can also be integrated into the high-voltage box 18, the thermal management device 13 or the control system 14 to increase the integration of the energy storage system and reduce the footprint of the energy storage system.

[0033] Continue to refer Figure 2 Optionally, the DC conversion module 12 may include: a first DC conversion unit 121; an input end of the first DC conversion unit 121 electrically connected to the energy storage inverter PSC; an output end of the first DC conversion unit 121 electrically connected to the thermal management device 13; and an output end of the first DC conversion unit 121 electrically connected to the control system 14. In this embodiment, the thermal management device 13 and the control system 14 share a first DC conversion unit 121 to obtain DC power. The first DC conversion unit 121 can draw power from the node between the high-voltage box 18 and the battery module 15. Compared to existing solutions, the provision of the first DC conversion unit 121 in this embodiment reduces overall costs, improves energy storage system efficiency, reduces losses, and reduces floor space.

[0034] Optionally, the DC conversion module 12 may include: a first DC conversion unit 121; the battery module 15 includes a first battery module 151 and a second battery module 152; the high-voltage box 18 includes a first high-voltage box 181 and a second high-voltage box 182; the first high-voltage box 181 is electrically connected to the first battery module 151; the second high-voltage box 182 is electrically connected to the second battery module 152; the first high-voltage box 181 is electrically connected to the second high-voltage box 182 through a first switch QF2; the second high-voltage box 182 is electrically connected to the input end of the first DC conversion unit 121 through a second switch QF4; the output end of the first DC conversion unit 121 is electrically connected to the thermal management device 13 through a third switch QF5; the output end of the first DC conversion unit 121 is electrically connected to the control system 14 through a fourth switch QF6. This embodiment further includes a first switch QF2, a second switch QF4, a third switch QF5, and a fourth switch QF6. The first end of the first switch QF2 is connected to the first high-voltage tank 181, the second end of the first switch QF2 is connected to the second high-voltage tank 182, the first end of the second switch QF4 is connected to the second high-voltage tank 182, and the second end of the second switch QF4 is connected to the input of the first DC converter unit 121. The output of the first DC converter unit 121 is electrically connected to the first end of the third switch QF5 and the first end of the fourth switch QF6, respectively. The second end of the third switch QF5 is connected to the thermal management device 13, and the second end of the fourth switch QF6 is connected to the control system 14. When the energy storage system is in an extreme environment, QF2 and QF4 are closed to draw DC power from the first busbar, and QF5 is closed to supply power to the thermal management device for heating / cooling. When the temperature of the energy storage device reaches a set safety threshold, QF6 is closed to activate control systems such as the battery management system, energy management system, and energy storage converter, completing the black start process. When the energy storage system is within a safe temperature range, QF2, QF4 and QF6 are directly closed to implement the black start process.

[0035] Figure 3A schematic diagram of the structure of another energy storage system provided in an embodiment of the present invention. Optionally, the energy storage system may include: a second DC conversion unit 122 and a third DC conversion unit 123; the input end of the second DC conversion unit 122 is electrically connected to the energy storage inverter PSC; the output end of the second DC conversion unit 122 is electrically connected to the thermal management device 13; the input end of the third DC conversion unit 123 is electrically connected to the energy storage inverter PSC; and the output end of the third DC conversion unit 123 is electrically connected to the control system 14. In this embodiment, the thermal management device 13 corresponds to the second DC conversion unit 122, and the control system 14 corresponds to the third DC conversion unit 123. The thermal management device 13 and the control system 14 respectively obtain DC power from their corresponding DC conversion units. The second DC conversion unit 122 and the third DC conversion unit 123 can draw power from the node between the high-voltage box 18 and the battery module 15. Compared with the existing solutions, the configuration of the second DC conversion unit 122 and the third DC conversion unit 123 in this embodiment reduces the overall cost, improves the efficiency of the energy storage system, reduces losses, and reduces the floor space.

[0036] Continue to refer Figure 3Optionally, the DC conversion module 12 may include: a second DC conversion unit 122 and a third DC conversion unit 123; the battery module 15 includes a first battery module 151 and a second battery module 152; the high-voltage box 18 includes a first high-voltage box 181 and a second high-voltage box 182; the first high-voltage box 181 is electrically connected to the first battery module 151; the second high-voltage box 182 is electrically connected to the second battery module 152; the first high-voltage box 181 is electrically connected to the second high-voltage box 182 through a first switch QF2; the second high-voltage box 182 is electrically connected to the input ends of the second DC conversion unit 122 and the third DC conversion unit 123 respectively through a second switch QF4; the output end of the second DC conversion unit 122 is electrically connected to the thermal management device 13 through a third switch QF5; the output end of the third DC conversion unit 123 is electrically connected to the control system 14 through a fourth switch QF6. This embodiment further includes a first switch QF2, a second switch QF4, a third switch QF5, and a fourth switch QF6. The first end of the first switch QF2 is connected to the first high-voltage tank 181, the second end of the first switch QF2 is connected to the second high-voltage tank 182, the first end of the second switch QF4 is connected to the second high-voltage tank 182, and the second end of the second switch QF4 is connected to the input ends of the second DC converter unit 122 and the third DC converter unit 123. The output end of the second DC converter unit 122 is electrically connected to the first end of the third switch QF5, the output end of the third DC converter unit 123 is electrically connected to the first end of the fourth switch QF6, the second end of the third switch QF5 is connected to the thermal management device 13, and the second end of the fourth switch QF6 is connected to the control system 14. When the energy storage system is in an extreme environment, QF2 and QF4 are closed to draw DC power from the first busbar, and QF5 is closed to supply power to the thermal management device for heating / cooling. When the energy storage device temperature reaches a set safety threshold, QF6 is closed to activate control systems such as the battery management system, energy management system, and energy storage converter, completing the black start process.

[0037] Based on the above embodiments, Figure 4 As shown, Figure 4A schematic diagram of a black start process of an energy storage system provided in this embodiment. Specifically, the thermal management device determines the current operating condition of the scene to determine whether it is an extremely cold / hot black start state under transportation / storage conditions. If so, QF2 and QF4 are closed to obtain DC power through the first bus, and QF5 is closed to supply the thermal management device for heating / cooling. Then, the thermal management device is used to confirm whether the temperature of the energy storage system reaches a safe temperature range. If the temperature reaches the safe temperature range, QF6 is closed to start the battery management system, energy management system, energy storage inverter and other control systems. If the temperature cannot reach the safe temperature range, heating / cooling continues to be performed through the thermal management device; if the current operating condition is not an extremely cold / hot black start state under transportation / storage conditions, QF2 and QF4 are directly closed to obtain DC power through the first bus, and QF6 is closed to start the battery management system, energy management system, energy storage inverter and other control systems. The energy management system performs grid power outage detection. When grid power is detected, the energy management system sends an off-grid working mode instruction to the PCS, and at the same time sends a start-up and high-voltage closing instruction to the BMS to achieve a black start.

[0038] An embodiment of the present utility model also provides an energy storage device. Figure 5 A schematic diagram of the structure of an energy storage device provided by an embodiment of the present utility model is shown as follows: Figure 5 As shown, the energy storage device provided in the embodiments of the present invention includes the energy storage system 200 of any embodiment of the present invention. The energy storage device can be an emergency power supply device or a backup power station, which is used to balance the power supply and demand of the power grid. Specifically, it can be used to smooth the peak of the power grid system and fill the valley of power consumption, storing power during low-demand periods and outputting power to the power grid system during peak demand periods. This embodiment does not specifically limit this.

[0039] Note that the above are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions are possible for those skilled in the art without departing from the scope of protection of the present invention. Therefore, while the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. An energy storage system, characterized in that: include: A first busbar, an energy storage inverter, a DC conversion module, a thermal management device, a control system, and at least one battery module; The energy storage inverter is electrically connected to the battery module and the first busbar, respectively, and is used to convert the direct current output by the battery module into alternating current and transmit it to the first busbar, and to convert the alternating current output by the first busbar into direct current to charge the battery module; The DC conversion module is electrically connected to the energy storage inverter and is used to transmit the DC power to the thermal management device; the thermal management device is used to perform heating or cooling operations on the energy storage system; the control system is electrically connected to the energy storage inverter and is used to control the energy storage inverter to enter a black start mode when the temperature of the energy storage system is within a safe temperature range.

2. The energy storage system according to claim 1, characterized in that The DC conversion module includes: a first DC conversion unit; The input end of the first DC conversion unit is electrically connected to the energy storage inverter; the output end of the first DC conversion unit is electrically connected to the thermal management device; and the output end of the first DC conversion unit is electrically connected to the control system.

3. The energy storage system according to claim 1, characterized in that The energy storage system includes: a second DC conversion unit and a third DC conversion unit; The input end of the second DC conversion unit is electrically connected to the energy storage inverter; the output end of the second DC conversion unit is electrically connected to the thermal management device; the input end of the third DC conversion unit is electrically connected to the energy storage inverter; and the output end of the third DC conversion unit is electrically connected to the control system.

4. The energy storage system according to claim 1, characterized in that The thermal management device includes at least: a heating device and a cooling device; The control system includes at least: a battery management system, an energy management system and an energy storage converter.

5. The energy storage system according to claim 1, characterized in that: The energy storage system further includes: a control cabinet, a second busbar, and a high-voltage box; the number of the battery modules is multiple; the high-voltage box is electrically connected to the battery modules in a one-to-one correspondence; The control cabinet is electrically connected to the energy storage inverter and the second busbar respectively, and is used to transmit the direct current output by the energy storage inverter to the second busbar; The high-voltage box is electrically connected to the second busbar, and is used to transmit the direct current on the second busbar to the corresponding battery module.

6. The energy storage system according to claim 5, characterized in that: The DC conversion module is integrated into the high-voltage box, the thermal management device or the control system.

7. The energy storage system according to claim 5, characterized in that: The DC conversion module includes: a first DC conversion unit; The battery module includes a first battery module and a second battery module; the high-voltage box includes a first high-voltage box and a second high-voltage box; the first high-voltage box is electrically connected to the first battery module; the second high-voltage box is electrically connected to the second battery module; The first high-voltage box is electrically connected to the second high-voltage box through a first switch; the second high-voltage box is electrically connected to the input end of the first DC conversion unit through a second switch; the output end of the first DC conversion unit is electrically connected to the thermal management device through a third switch; and the output end of the first DC conversion unit is electrically connected to the control system through a fourth switch.

8. The energy storage system according to claim 5, characterized in that: The DC conversion module includes: a second DC conversion unit and a third DC conversion unit; The battery module includes a first battery module and a second battery module; the high-voltage box includes a first high-voltage box and a second high-voltage box; the first high-voltage box is electrically connected to the first battery module; the second high-voltage box is electrically connected to the second battery module; The first high-voltage box is electrically connected to the second high-voltage box through a first switch; the second high-voltage box is electrically connected to the input ends of the second DC conversion unit and the third DC conversion unit respectively through a second switch; the output end of the second DC conversion unit is electrically connected to the thermal management device through a third switch; and the output end of the third DC conversion unit is electrically connected to the control system through a fourth switch.

9. An energy storage device, characterized in that: An energy storage system comprising the energy storage system according to any one of claims 1 to 8.

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