An energy storage system

Abstract

The application discloses an energy storage system, comprising an AC-DC converter, an auxiliary device, an energy storage converter and a plurality of first DC-DC converters; the first ends of the plurality of first DC-DC converters are connected to corresponding battery packs, and the second ends of the plurality of first DC-DC converters are connected to an equalization bus; the DC end of the energy storage converter is connected to a battery cluster, the AC end of the energy storage converter is connected to the AC end of the AC-DC converter, and the AC end of the energy storage converter is used for connecting a power grid; the DC end of the AC-DC converter is connected to the equalization bus; and the battery cluster comprises a plurality of battery packs. The auxiliary device is connected to the equalization bus, and in a black start process, the battery packs can be used to supply power to the auxiliary device, and an USP does not need to be additionally arranged, thereby reducing the operation and maintenance cost of the energy storage system.

Description

Technical Field

[0001] This application relates to the field of electronic power technology, and specifically to an energy storage system. Background Technology

[0002] Black start refers to the process of gradually restoring power to the entire power system when it is completely or partially out of service due to a fault, through its own starting capability or with the help of other external power sources (such as uninterruptible power supply, UPS).

[0003] During the black start process of a power system, especially in the event of a power grid failure, a UPS needs to be installed in the power system to provide auxiliary power supply and achieve a black start. Summary of the Invention

[0004] In view of this, this application provides an energy storage system.

[0005] In a first aspect, embodiments of this application provide an energy storage system, including an AC-DC converter, auxiliary equipment, an energy storage converter, and a plurality of first DC-DC converters;

[0006] The first terminals of the plurality of first DC-DC converters are connected to the corresponding battery packs, and the second terminals of the plurality of first DC-DC converters are connected to the equalization bus.

[0007] The DC terminal of the energy storage converter is connected to the battery cluster, and the AC terminal of the energy storage converter is connected to the AC terminal of the AC-DC converter. The AC terminal of the energy storage converter is used to connect to the power grid. The DC terminal of the AC-DC converter is connected to the balancing bus. The battery cluster includes multiple battery packs.

[0008] The auxiliary equipment is connected to the equalization bus.

[0009] In one possible implementation, in the event of a power grid outage, the battery pack supplies power to the auxiliary equipment via the balancing bus.

[0010] In one possible implementation, the energy storage system further includes a second DC-DC converter;

[0011] The auxiliary equipment is connected to the equalization bus via the second DC-DC converter;

[0012] The AC-DC converter is connected to the equalization bus via the second DC-DC converter.

[0013] In one possible implementation, the DC terminal of the energy storage converter is connected to multiple battery clusters connected in parallel.

[0014] In one possible implementation, when the DC terminal voltage of the energy storage converter is lower than the startup voltage of the energy storage converter, the AC-DC converter charges the battery pack through the balancing bus.

[0015] When the DC terminal voltage of the energy storage converter is higher than or equal to the startup voltage of the energy storage converter, the energy storage converter starts to charge the battery pack or the AC-DC converter charges the battery pack through the balancing bus.

[0016] In one possible implementation, when the charge of at least one of the battery packs is below a threshold, the AC-DC converter charges the battery packs via the balancing bus.

[0017] In one possible implementation, when the energy of the battery packs connected to the plurality of first DC-DC converters is different, the plurality of first DC-DC converters control the discharge power or charging power of the corresponding battery packs to control the energy balance of the battery packs connected to the plurality of first DC-DC converters.

[0018] In one possible implementation, when the battery packs connected to the multiple first DC-DC converters have different energies, the first DC-DC converter corresponding to the battery pack with energy lower than the average energy draws power from the balancing bus, and the first DC-DC converter corresponding to the battery pack with energy higher than the average energy discharges to the balancing bus.

[0019] In one possible implementation, the auxiliary equipment includes at least one of fire-fighting equipment, a fan, or a controller.

[0020] The energy storage system provided in this application includes an AC-DC converter, auxiliary equipment, an energy storage converter, and multiple first DC-DC converters. The first terminals of the multiple first DC-DC converters are connected to corresponding battery packs, and the second terminals of the multiple first DC-DC converters are connected to an balancing bus. The DC terminals of the energy storage converters are connected to the battery packs, and the AC terminals of the energy storage converters are connected to the AC terminals of the AC-DC converters, which are used to connect to the power grid. The DC terminals of the AC-DC converters are connected to the balancing bus. The battery packs include multiple battery packs. The auxiliary equipment is connected to the balancing bus. During black start, the battery packs can be used to power the auxiliary equipment through the balancing bus, eliminating the need for an additional USB power supply (USP) and reducing the operation and maintenance costs of the energy storage system. Attached Figure Description

[0021] Figure 1 A schematic diagram of an energy storage system provided in an embodiment of this application;

[0022] Figure 2A schematic diagram of a second energy storage system provided in the embodiments of this application;

[0023] Figure 3 A schematic diagram of a third energy storage system provided in the embodiments of this application;

[0024] Figure 4 A schematic diagram of the fourth energy storage system provided in the embodiments of this application;

[0025] Figure 5 A schematic diagram of the fifth energy storage system provided in the embodiments of this application;

[0026] Figure 6 A schematic diagram of the sixth energy storage system provided in the embodiments of this application;

[0027] Figure 7 A schematic diagram of the seventh energy storage system provided in the embodiments of this application;

[0028] Figure 8 A schematic diagram of the eighth energy storage system provided in the embodiments of this application;

[0029] Figure 9 A schematic diagram of the ninth energy storage system provided in the embodiments of this application;

[0030] Figure 10 A schematic diagram of the tenth energy storage system provided in the embodiments of this application;

[0031] Figure 11 A schematic diagram of the eleventh energy storage system provided in the embodiments of this application;

[0032] Figure 12 A schematic diagram of the twelfth type of energy storage system provided in the embodiments of this application;

[0033] Figure 13 A schematic diagram of the thirteenth energy storage system provided in this application embodiment;

[0034] Figure 14 This is a schematic diagram of the fourteenth energy storage system provided in the embodiments of this application. Detailed Implementation

[0035] In some power systems, UPS systems are typically configured to supply power to auxiliary equipment during the initial black start phase to support the power system's black start capability. However, this increases the cost of the power system.

[0036] To address this issue, this application provides an energy storage system that uses a battery pack to power auxiliary equipment via a balancing bus, eliminating the need for a UPS and reducing the cost of manufacturing and maintenance of the energy storage system.

[0037] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0038] like Figure 1 As shown, Figure 1 This is a schematic diagram of an energy storage system provided in an embodiment of this application. The energy storage system includes an AC-DC converter (also called an alternating current to direct current converter), auxiliary equipment, a power conversion system (PCS), and multiple first DC-DC converters (also called first direct current to direct current converters or equalization converters);

[0039] The first terminals of multiple first DC-DC converters are connected to the corresponding battery packs, and the second terminals of multiple first DC-DC converters are connected to the balancing bus; the DC terminal of the PCS is connected to the battery pack, the AC terminal of the PCS is connected to the AC terminal of the AC-DC converter, and the AC terminal of the PCS is used to connect to the power grid; the DC terminal of the AC-DC converter is connected to the balancing bus; auxiliary equipment is connected to the balancing bus.

[0040] The number of first DC-DC converters is the same as the number of battery packs, with a one-to-one correspondence between the first DC-DC converter and each battery pack. The positive and negative terminals of the first DC-DC converter can be connected to the positive and negative terminals of the battery packs, while the positive and negative terminals of the second DC-DC converter are connected to the positive and negative terminals of the balancing bus. The first DC-DC converter is a bidirectional DC-DC converter. When the battery packs are discharging, the first terminal of the first DC-DC converter receives energy, performs a boost or buck conversion, and then transmits the energy to the balancing bus through the second terminal. When the battery packs are charging, the second terminal of the first DC-DC converter can obtain energy from the balancing bus, perform a boost or buck conversion, and then transmit the energy to the corresponding battery pack through the first terminal to charge the battery packs.

[0041] An AC-DC converter is used to convert AC power supplied by the grid or PCS into DC power. The positive and negative terminals of the AC-DC converter are connected to the positive and negative terminals of the PCS's AC power; the positive and negative terminals of the AC-DC converter are connected to the positive and negative terminals of the balancing bus. When a battery pack needs charging, the AC-DC converter converts the AC power supplied by the grid into DC power and supplies it to the balancing bus so that the first DC-DC converter can charge the corresponding battery pack. When the battery pack is discharging, the AC-DC converter can also draw power from the balancing bus, converting the DC power back into AC power and supplying it to the grid or other AC loads.

[0042] The power control system (PCS) is used to convert direct current (DC) to alternating current (AC), or vice versa. The positive and negative terminals of the PCS's AC outputs connect to the positive and negative terminals of the AC-DC converter; the positive and negative terminals of the PCS's DC outputs connect to the positive and negative terminals of the battery pack. When the battery pack is discharging, the PCS converts the DC power supplied by the battery pack into AC power to ensure compatibility with the power grid or load. When the battery pack is charging, the PCS converts the AC power supplied by the power grid into DC power to charge the battery pack within it.

[0043] Auxiliary equipment can be devices that require direct current (DC). These auxiliary devices operate by drawing alternating current (AC) from the balancing bus after connecting to it. The energy in the balancing bus can come from a battery pack or an AC-DC converter.

[0044] In this embodiment of the application, in the event of a power grid outage, the battery pack can be used to supply power to auxiliary equipment through the balancing bus.

[0045] The battery pack delivers energy to the balancing bus via the corresponding first DC-DC converter, and the auxiliary equipment draws power from the balancing bus.

[0046] Alternatively, when the PCS starts up, the energy in the battery pack is sequentially delivered to the equalization bus through the PCS and the AC-DC converter, and the auxiliary equipment draws power from the equalization bus.

[0047] The energy storage system provided in this application embodiment allows auxiliary equipment to be directly connected to the balancing bus. During the initial black start phase, the battery pack powers the auxiliary equipment without the need for a UPS, thus reducing the cost of energy storage system manufacturing and subsequent maintenance.

[0048] In this embodiment, the DC terminal of the PCS can be connected to multiple parallel battery clusters, which are connected to a battery cluster bus. Each battery cluster includes multiple first DC-DC converters and multiple battery packs connected in series. The number of battery packs within a battery cluster is the same as and corresponds one-to-one with the number of first DC-DC converters.

[0049] There is no limit to the number of battery clusters connected to the PCS, and there is also no limit to the number of battery packs and first DC-DC converters within each battery cluster. The number of battery packs and first DC-DC converters within the same battery cluster must be the same and connected in a one-to-one correspondence. The number of battery packs within each battery cluster can be the same or different.

[0050] It should be noted that the first terminal, second terminal, AC terminal, or DC terminal of each device described in the embodiments of this application (such as the first DC-DC converter, the second DC-DC converter, the AC-DC converter, the PCS, the battery pack, the battery cluster, and the auxiliary power transformer) all include positive and negative terminals, which will not be repeated below.

[0051] In one possible implementation, the energy storage system may also include a second DC-DC converter (also called a second DC-DC converter). The second DC-DC converter is used for boosting or bucking the voltage.

[0052] like Figure 2 As shown, Figure 2 This is a schematic diagram of an energy storage system provided in an embodiment of this application.

[0053] When auxiliary equipment is connected to the balancing bus, it can be connected to the balancing bus via a second DC-DC converter. Figure 2 In the energy storage system shown, the current path for the battery pack to supply power to the auxiliary equipment can be: battery pack—first DC-DC converter—balancing bus—second DC-DC converter—auxiliary equipment; or battery pack—PCS—AC-DC converter—balancing bus—second DC-DC converter—auxiliary equipment.

[0054] The second DC-DC converter is used for boosting or bucking voltage. In this embodiment, the second DC-DC converter can adjust the voltage on the balancing bus to the operating voltage of the auxiliary equipment to ensure that the auxiliary equipment can operate normally.

[0055] like Figure 3 As shown, the AC-DC converter can also be connected to the balancing bus via a second DC-DC converter. The second DC-DC converter is used to match the voltage levels between the DC terminal of the AC-DC converter and the balancing bus. Figure 3 In the energy storage system shown, the current path for the battery pack to supply power to the auxiliary equipment can be either battery pack—first DC-DC converter—balancing bus—second DC-DC converter—auxiliary equipment; or battery pack—PCS—AC-DC converter—auxiliary equipment.

[0056] In this embodiment, the auxiliary equipment is other equipment besides the heat dissipation air conditioner. Auxiliary equipment includes, for example, one or more of fire-fighting equipment, fans, or controllers. Figure 4 As shown, Figure 4 The auxiliary equipment in the energy storage system shown includes fire-fighting equipment, air conditioning, and controllers.

[0057] Firefighting equipment, such as fire extinguishers, automatic fire suppression systems, and smoke detectors, is used to prevent and control the occurrence and spread of fires. In the event of a fire, firefighting equipment can respond quickly and take measures to protect the safety of energy storage systems and prevent equipment damage and personnel injury.

[0058] Fans are used to enhance the heat dissipation capacity of energy storage systems, especially when devices such as PCS and battery packs generate a large amount of heat during operation. Fans can also be used to maintain the internal environmental conditions of energy storage systems, such as providing ventilation and expelling harmful gases, to ensure the normal operation of the energy storage system.

[0059] The controller can be used to operate the Energy Management System (EMS). It monitors and controls the operating status of the energy storage system, such as battery pack charging and discharging management, battery pack energy balancing, and fault diagnosis. By monitoring the operation of various components of the energy storage system in real time, the controller can optimize energy distribution and utilization, improving the overall efficiency and reliability of the energy storage system.

[0060] Typically, the heat generated during PCS operation is correlated with the PCS's output power. If the PCS outputs high power before the cooling system starts, it may be damaged due to overheating. Therefore, during black start, the PCS needs to initially output low power to power the cooling system. Once the cooling system starts, it dissipates the heat generated by the PCS, at which point the PCS can then output higher power to supply power, achieving a black start for the power system. However, this can result in a slower black start speed, leading to power interruptions.

[0061] To address this issue, the energy storage system provided in this application embodiment may further include a cooling air conditioner, such as... Figure 5 and Figure 6 As shown. The cooling air conditioner is directly connected to the balancing bus or the DC terminal of the PCS. During black start, the battery pack can directly power the cooling air conditioner, enabling it to start quickly for heat dissipation. The PCS can then output higher power without overheating. This eliminates the need for the PCS to power the cooling air conditioner at a lower power output until it starts, thus improving the speed of black start.

[0062] Figure 5 In the energy storage system shown, the cooling air conditioner is connected to the balancing bus; Figure 6 In the energy storage system shown, the cooling air conditioner is connected to the DC terminal of the PCS. In practical applications, the cooling air conditioner can also be connected to both the balancing bus and the DC terminal of the PCS. Regardless of whether the cooling air conditioner is connected to the balancing bus or the DC terminal of the PCS, during black start-up, the battery pack supplies power to the cooling air conditioner without going through the PCS.

[0063] Thermal air conditioning is used to control the internal ambient temperature of energy storage systems, preventing damage or performance degradation of equipment due to high temperatures. Through active cooling, thermal air conditioning can quickly dissipate the heat generated by devices such as PCS during operation, ensuring that the equipment operates within a safe temperature range.

[0064] As an example, if the heat dissipation components (such as fans or compressors) inside a thermal air conditioner require AC power, an inverter can be integrated inside the thermal air conditioner to convert DC power to AC power to meet the electrical needs of the thermal air conditioner. This eliminates the need for a separate inverter for the thermal air conditioner within the energy storage system, reducing system complexity and potentially improving energy efficiency, as the internal converter can more optimally match the electrical requirements of the thermal air conditioner.

[0065] During black start, the cooling air conditioner no longer relies on the PCS for power supply, but instead draws power directly from the battery pack for rapid startup. After the cooling air conditioner starts, it quickly dissipates the heat generated by the PCS and other devices, ensuring that the PCS can output high power immediately after startup without overheating, thereby accelerating the black start process. The energy storage system provided in this application improves the speed and efficiency of black start by optimizing the power transmission path. The combination of the rapid startup of the cooling air conditioner and the high-power output of the PCS reduces system recovery time and ensures the rapid and stable operation of the power system.

[0066] In one possible implementation, the energy storage system includes a cooling air conditioner and a second DC-DC converter. The energy storage system can be as follows: Figures 7-10 As shown.

[0067] like Figure 7 and Figure 8 As shown, auxiliary equipment can be connected to the balancing bus via a second DC-DC converter, and the cooling air conditioner can be directly connected to the balancing bus. Figure 7 (as shown) or PCS DC terminal ( Figure 8 (As shown).

[0068] The second DC-DC converter can perform voltage boosting or bucking operations according to the operating voltage requirements of the auxiliary equipment, ensuring that the auxiliary equipment can operate normally. Through the second DC-DC converter, the battery pack can supply power to the auxiliary equipment through the balancing bus, enabling the auxiliary equipment to operate normally during the initial black start phase.

[0069] like Figure 9 As shown, when the cooling air conditioner is connected to the balancing bus, the auxiliary equipment and the cooling air conditioner can be connected to the balancing bus through the second DC-DC converter.

[0070] like Figure 10 As shown, when the cooling air conditioner is connected to the balancing bus through the second DC-DC converter, the auxiliary equipment can be directly connected to the balancing bus.

[0071] In one possible implementation, the AC-DC converter can be connected to the balancing bus via a second DC-DC converter. The energy storage system can be as follows: Figures 11-13 As shown.

[0072] When the AC-DC converter is connected to the balancing bus via a second DC-DC converter, the cooling air conditioner can be directly connected to the balancing bus. Figure 11 (as shown) or PCS DC terminal ( Figure 12 As shown), it can also be connected to the equalization bus via a second DC-DC converter (as shown). Figure 13 (As shown).

[0073] In one possible implementation, Figures 1-13 The energy storage system shown may also include an auxiliary power transformer. For example... Figure 14 As shown, the auxiliary power transformer is connected between the AC terminal of the AC-DC converter and the AC terminal of the PCS.

[0074] The auxiliary power transformer is used to step up or step down the input AC power to match the voltage at the AC terminal of the AC-DC converter with the voltage at the AC terminal of the PCS, or to match the voltage at the AC terminal of the AC-DC converter with the voltage of the power grid.

[0075] The energy storage system provided in this application embodiment enables the battery pack to directly power the cooling air conditioner during black start, allowing the cooling air conditioner to start quickly. The PCS can output energy at a higher power during startup, thus achieving a rapid black start.

[0076] In addition, the energy storage system provided in this application embodiment can also realize the charging start-up of the battery pack and the energy balance of each battery pack.

[0077] In some implementations, if the DC terminal voltage of the PCS is lower than the PCS startup voltage, the PCS cannot start and therefore cannot use the energy provided by the grid to charge the battery pack.

[0078] The embodiments provided in this application Figures 1-14 In the energy storage system shown, the AC-DC converter is connected between the power grid and the balancing bus. When the power grid is needed to charge the battery pack, if the PCS cannot start (i.e., the energy of the battery pack in the current battery cluster is too low, and the DC terminal voltage of the PCS is lower than the PCS start-up voltage), the AC-DC converter converts the AC power provided by the power grid into DC power and transmits it to the balancing bus. Then, multiple first DC-DC converters draw power from the balancing bus to charge the corresponding battery pack.

[0079] In one possible implementation, after the battery pack has been charging for a period of time, once the DC terminal voltage of the PCS reaches the PCS startup voltage, the PCS is then used to continue charging the battery pack.

[0080] When charging the battery pack via an AC-DC converter, the energy in the grid undergoes at least two stages of conversion: the AC-DC converter and the first DC-DC converter. However, when charging the battery pack via a PCS (Power Control System), the energy in the grid only undergoes one stage of conversion. The energy loss is lower with a single-stage conversion compared to a two-stage conversion. Therefore, when the PCS is operational, switching from AC-DC converter charging to PCS charging can reduce energy loss and improve energy utilization to some extent.

[0081] Of course, if it is necessary to use the power grid to charge the battery pack, and the PCS can start (i.e., the DC terminal voltage of the PCS is higher than or equal to the PCS start-up voltage), the PCS can be used directly to charge the battery pack to improve energy utilization.

[0082] Typically, the energy within multiple battery packs may vary; for example, the energy within different battery packs differs after charging or discharging. Over time, this can lead to variations in battery pack lifespan, affecting the performance of the energy storage system and increasing maintenance and replacement costs. In some implementations, energy balancing within a battery cluster is typically achieved. This requires the battery cluster to be connected to the cluster bus via a cluster DC-DC converter to achieve inter-cluster energy balancing. However, the switching between multiple converter stages results in energy losses during energy balancing.

[0083] In one possible implementation, the AC-DC converter charges the battery pack via an equalization bus when the charge of at least one battery pack is below a threshold.

[0084] This threshold is used to measure whether the battery pack is low on power, and the specific value of the threshold can be set by technicians. When there are battery packs in the energy storage system with power levels below the threshold, the AC-DC converter delivers energy from the grid to the balancing bus. The battery packs with power levels below the threshold draw power from the balancing bus to charge the corresponding battery packs, at least to the threshold level, but not exceeding the upper limit of the battery pack's power level.

[0085] The embodiments provided in this application Figures 1-14 In the energy storage system shown, each battery in each battery cluster is connected to the balancing bus through the first DC-DC converter. The balancing bus enables energy balancing of battery packs within the same battery cluster and battery packs in different battery clusters.

[0086] In one possible implementation, when the battery packs are used to power the cooling air conditioner and other auxiliary equipment via a balancing bus, each first DC-DC converter can control the discharge power according to the charge level of its corresponding battery pack, so as to achieve energy balance among the battery packs. For example, the discharge power of the battery pack with higher charge level is greater than that of the battery pack with lower charge level.

[0087] As an example, when the battery pack's charge level is greater than the balanced charge level, the corresponding first DC-DC converter increases the discharge power; when the battery pack's charge level is less than or equal to the balanced charge level, the corresponding first DC-DC converter decreases the discharge power. The balanced charge level can be set by a technician.

[0088] In another possible implementation, when charging each battery pack using AC-DC converters, each first DC-DC converter needs to draw energy from the balancing bus to charge its corresponding battery pack. Each first DC-DC converter can control the charging power according to the charge level of the corresponding battery pack to achieve energy balance among the battery packs. For example, the charging power of a battery pack with a higher charge level is less than that of a battery pack with a lower charge level.

[0089] As an example, when the battery pack's charge level is greater than the balanced charge level, the first DC-DC converter corresponding to that battery pack reduces the charging power; when the battery pack's charge level is less than or equal to the balanced charge level, the first DC-DC converter corresponding to that battery pack increases the charging power. The balanced charge level can be set by a technician.

[0090] In another possible implementation, the battery packs can also achieve energy balance by transferring energy between them via a balancing bus. As an example, if the first battery pack has a higher charge than the second battery pack, the first battery pack transfers energy to the balancing bus through its corresponding first DC-DC converter, while the second battery pack obtains energy from the balancing bus through its corresponding first DC-DC converter, thus achieving energy balance between the first and second battery packs.

[0091] Specifically, when the battery pack's charge level is greater than the average charge level, the corresponding first DC-DC converter controls the battery pack to discharge; when the battery pack's charge level is less than the average charge level, the corresponding first DC-DC converter controls the battery pack to charge; when the battery pack's charge level equals the average charge level, the corresponding first DC-DC converter does not operate. The average charge level is the average charge level of all battery packs in the energy storage system. For example, the average charge level is the ratio of the total charge level of all battery packs in the energy storage system to the total number of battery packs in the energy storage system. Through energy transfer between battery packs, energy balance among the battery packs within the energy storage system can be achieved.

[0092] In the energy storage system provided in this application embodiment, multiple battery packs within multiple battery clusters can achieve energy balancing through a balancing bus. Energy balancing can be achieved not only through energy transfer between battery packs but also by controlling the charging and discharging power of each battery pack. Even battery packs within different battery clusters can achieve energy balancing through the balancing bus, and there is no need to install a battery cluster DC-DC converter. This not only reduces the manufacturing and maintenance costs of the energy storage system but also avoids the energy loss caused by the battery cluster DC-DC converter during the energy balancing process.

[0093] Furthermore, compared to achieving energy balancing through energy transfer between battery packs, controlling the charging and discharging power of each battery pack to achieve energy balancing can improve energy utilization and reduce energy loss. Previously, energy was converted through at least two stages of conversion via two first DC-DC converters, but during charging and discharging, each battery pack only undergoes conversion via its corresponding first DC-DC converter.

[0094] Furthermore, the energy transfer between battery packs to achieve energy equalization may be a separate process from the charging and discharging process. In addition to the charging and discharging process, an extra energy transfer is required between battery packs; that is, the energy in the battery pack must undergo at least two additional conversions by the first DC-DC converter. The aforementioned battery pack charging process refers to the process of charging the battery pack, while the battery pack discharging process refers to the process of discharging the battery pack to power auxiliary equipment or cooling / air conditioning systems. This battery pack charging and discharging process differs somewhat from the charging and discharging process for energy equalization between battery packs.

[0095] In this embodiment, during battery pack charging, the energy loss generated by the AC-DC converter and the first DC-DC converter is a normal loss during the charging process. This charging loss occurs through the AC-DC converter and the first DC-DC converter and is not considered an unnecessary loss during energy balancing. During battery pack discharging, the battery pack can directly transfer energy to the balancing bus via the first DC-DC converter. If the cooling air conditioner or auxiliary equipment is directly connected to the balancing bus, it can directly draw power from the balancing bus. Even if the cooling air conditioner or auxiliary equipment is connected to the balancing bus via the second DC-DC converter, the energy loss generated by the first and second DC-DC converters during discharge is a normal loss during the discharge process. This discharge loss occurs through the second DC-DC converter and is not considered an unnecessary loss during energy balancing.

[0096] In other words, the energy storage system provided in this application embodiment can achieve energy balance of multiple battery packs within a multi-battery cluster during the charging and discharging process, without causing additional energy loss due to energy balance, thereby improving energy utilization.

[0097] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An energy storage system, characterized by, Includes AC-DC converters, auxiliary equipment, energy storage converters, and multiple first DC-DC converters; The first terminals of the plurality of first DC-DC converters are respectively connected to the corresponding battery packs, and the second terminals of the plurality of first DC-DC converters are connected to the equalization bus. The DC terminal of the energy storage converter is connected to the battery cluster, and the AC terminal of the energy storage converter is connected to the AC terminal of the AC-DC converter. The AC terminal of the energy storage converter is used to connect to the power grid. The DC terminal of the AC-DC converter is connected to the balancing bus. The battery cluster includes multiple battery packs. The auxiliary equipment is connected to the equalization bus.

2. The energy storage system of claim 1, wherein, In the event of a power grid outage, the battery pack supplies power to the auxiliary equipment via the balancing bus.

3. The energy storage system of claim 1, wherein, The energy storage system also includes a cooling air conditioner, which is connected to the equalization bus or the DC terminal of the energy storage converter.

4. The energy storage system of claim 1, wherein, The energy storage system also includes a second DC-DC converter; The auxiliary equipment is connected to the equalization bus via the second DC-DC converter; The AC-DC converter is connected to the equalization bus via the second DC-DC converter.

5. The energy storage system of claim 1, wherein, The DC terminal of the energy storage converter is connected to multiple parallel battery clusters.

6. The energy storage system of claim 1, wherein, When the DC terminal voltage of the energy storage converter is lower than the start-up voltage of the energy storage converter, the AC-DC converter charges the battery pack through the balancing bus; When the DC terminal voltage of the energy storage converter is higher than or equal to the startup voltage of the energy storage converter, the energy storage converter starts to charge the battery pack or the AC-DC converter charges the battery pack through the balancing bus.

7. The energy storage system of claim 1, wherein, When the charge of at least one of the battery packs is below a threshold, the AC-DC converter charges the battery packs through the equalization bus.

8. The energy storage system of claim 1, wherein, When the energy of the battery packs connected to the multiple first DC-DC converters is different, the multiple first DC-DC converters control the discharge power or charging power of the corresponding battery packs to control the energy balance of the battery packs connected to the multiple first DC-DC converters.

9. The energy storage system of claim 1, wherein, When the energy of the battery packs connected to the multiple first DC-DC converters is different, the first DC-DC converter corresponding to the battery pack with energy lower than the average energy draws power from the balancing bus, and the first DC-DC converter corresponding to the battery pack with energy higher than the average energy discharges to the balancing bus.

10. The energy storage system of claim 1, wherein, The auxiliary equipment includes at least one of fire-fighting equipment, fans, or controllers.

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