Energy storage system, and circuit protection method for energy storage system

Abstract

The present application provides an energy storage system, and a circuit protection method for an energy storage system. A power supply branch of the energy storage system is provided with a relay and a fuse; the breaking current of the relay is greater than or equal to first current, and is smaller than or equal to second current; the fusing current of the fuse is greater than or equal to third current, and is smaller than or equal to fourth current, and the fourth current is greater than or equal to the first current, and is smaller than the second current. Therefore, global-range fault prevention can be implemented on the energy storage system.

Description

Energy storage system and circuit protection method for energy storage system

[0001] This application claims priority to the Chinese patent applications filed with the China Patent Office on March 15, 2024, with application numbers 202410304657.0 and 202420514006.X, respectively. The entire contents of the above applications are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to an energy storage system and a circuit protection method for the energy storage system. Background Art

[0003] When a short circuit occurs in the energy storage system, the lithium battery and other components in the energy storage system will be severely damaged, so the circuit of the energy storage system needs to be protected. SUMMARY OF THE INVENTION

[0004] In related art, fuses are installed in high-voltage boxes to provide short-circuit protection for energy storage systems. However, this approach has low safety performance and cannot protect the energy storage system from global faults.

[0005] In a first aspect, the present application provides an energy storage system, comprising at least one power supply branch, wherein the power supply branch comprises:

[0006] at least one battery pack including an input terminal and an output terminal;

[0007] The high-voltage box includes a first interface, a second interface, a third interface, and a fourth interface, wherein the first interface is electrically connected to the input end, the second interface is electrically connected to the output end, and the third interface and the fourth interface are electrically connected to the target device respectively;

[0008] Wherein, the high-voltage box further includes a first fuse and a first relay, and the first fuse and the first relay are arranged between the first interface and the third interface, or the first fuse and the first relay are arranged between the second interface and the fourth interface;

[0009] The fusing current of the first fuse is greater than or equal to a preset first current and less than or equal to a preset second current; the disconnecting current of the first relay is greater than or equal to a preset third current and less than or equal to a preset fourth current; the fourth current is greater than or equal to the first current and less than the second current.

[0010] In a second aspect, the present application further provides a circuit protection method for an energy storage system, wherein the energy storage system includes at least one power supply branch, the power supply branch includes a high-voltage box, the high-voltage box includes a first fuse and a first relay, and the method includes:

[0011] When it is detected that the fault current of the power supply branch is less than or equal to a preset critical current, a cut-off instruction is sent to the first relay to disconnect the power supply branch;

[0012] When the fault current is greater than the critical current, the first fuse blows to disconnect the power supply branch. Beneficial effects

[0013] The energy storage system provided in the present application is configured with a first fuse and a first relay in a high-voltage box. The first breaking current of the first fuse is greater than or equal to the first current and less than or equal to the second current, and the first breaking current of the first relay is greater than or equal to the third current and less than or equal to the fourth current. The fourth current is greater than or equal to the first current and less than the second current. Thus, when a small fault current occurs in the power supply branch, the relay can be used to cut off the power supply branch. At the same time, when a large fault current occurs in the power supply branch, the fuse can be used to cut off the power supply branch. This achieves global fault protection for the energy storage system and improves the safety performance of the energy storage system.

[0014] The circuit protection method for an energy storage system provided in the present application sends a disconnection instruction to a first relay to disconnect the power supply branch when it detects that the fault current of the power supply branch is less than or equal to a preset critical current; when the fault current is greater than the preset critical current, the first fuse blows to disconnect the power supply branch, thereby achieving circuit disconnection protection for the energy storage system under the full range of fault currents, protecting the energy storage system to the greatest extent, facilitating maintenance of the energy storage system, and improving the safety of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG1 is a schematic block diagram of an energy storage system provided by the present application;

[0016] FIG2 is a flow chart of a method for protecting an energy storage system according to the present invention;

[0017] FIG3 is another flow chart of the energy storage system protection method provided in the present application;

[0018] FIG4 is a schematic diagram of the protection range of the relay and fuse provided in this application.

[0019] Explanation of the accompanying drawings: 10 is the power supply branch, 101 is the high-voltage box, 102 is the battery pack, FU1 is the first fuse, FU2 is the second fuse, FU3 is the third fuse, J1 is the first relay, J2 is the second relay, B+ is the first interface, B- is the second interface, P+ is the third interface, P- is the fourth interface, TK is the trip unit, 20 is the energy storage converter, and 30 is the load switch. Modes for Carrying Out the Invention

[0020] In the description of this application, unless otherwise specified or limited, the terms "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0021] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, with the first feature having a higher horizontal height than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, with the first feature having a lower horizontal height than the second feature.

[0022] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings. They are intended to facilitate description and simplify operation, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and do not have any special meanings.

[0023] Please refer to FIG1 , which is a schematic block diagram of the energy storage system provided in this application.

[0024] As shown in FIG1 , an energy storage system includes at least one power supply branch 10 , which includes:

[0025] At least one battery pack 101, including an input terminal and an output terminal;

[0026] The high-voltage box 102 includes a first interface B+, a second interface B-, a third interface P+, ​​and a fourth interface P-. The first interface B+ is electrically connected to an input terminal, the second interface B- is electrically connected to an output terminal, and the third interface P+ and the fourth interface P- are electrically connected to target devices respectively.

[0027] The high-voltage box 102 further includes a first fuse FU1 and a first relay J1. The first fuse FU1 and the first relay J1 are arranged between the first interface B+ and the third interface P+, ​​or the first fuse FU1 and the first relay J1 are arranged between the second interface B- and the fourth interface P-.

[0028] The melting current of the first fuse FU1 is greater than or equal to the preset first current and less than or equal to the preset second current; the disconnecting current of the first relay J1 is greater than or equal to the preset third current and less than or equal to the preset fourth current; the fourth current is greater than or equal to the first current and less than the second current.

[0029] In this embodiment, the disconnection current of the first relay J1 is configured to disconnect the current of the first relay J1, and the melting current of the first fuse FU1 is configured to melt the first fuse FU1. The current for melting the first fuse FU1 is set between the first current and the second current, and the current for disconnecting the first relay J1 is set between the third current and the fourth current. The fourth current is greater than or equal to the first current and less than the second current. Not only can the first relay J1 be directly used to cut off the power supply branch 10 when a small fault current occurs in the power supply branch 10, but the first fuse FU1 can also be directly used to cut off the power supply branch 10 when a large fault current occurs in the power supply branch 10, thereby achieving global coverage of the fault current, improving the safety performance of the energy storage system, and reducing the maintenance cost of the energy storage system.

[0030] Specifically, when a short circuit fault occurs in the power supply branch 10, if the fault current of the power supply branch 10 is between the third current and the fourth current, the first relay J1 can be controlled to disconnect to cut off the circuit of the corresponding power supply branch 10; if the fault current of the power supply branch 10 is between the fourth current and the second current, the first fuse FU1 can be blown to cut off the circuit of the corresponding power supply branch 10; if the fault current of the power supply branch 10 is between the first current and the fourth current and the first relay J1 is stuck, the first fuse FU1 can be blown to cut off the circuit of the corresponding power supply branch 10; if the fault current of the power supply branch 10 is between the first current and the fourth current and the first relay J1 is not stuck, the first relay J1 can be controlled to disconnect to cut off the circuit of the corresponding power supply branch 10.

[0031] It should be noted that the on and off of the relays in the energy storage system can be controlled by the battery management system (BMS) where the energy storage system is located.

[0032] In some implementations, as shown in FIG4 , when the fault current of the power supply branch 10 is greater than or equal to the first current and less than the fourth current, the melting time of the first fuse FU1 is less than the disconnection time of the first relay J1 .

[0033] Specifically, during normal operation of the relay, if the current in the power supply branch 10 is too large, the relay is prone to sticking. At the same time, if the fault current of the power supply branch 10 is greater than the first current, the fault current can melt the first fuse FU1. Therefore, the fault current is necessarily large, and the probability of the first relay J1 sticking is also relatively high. To this end, the present application can use the first fuse FU1 to cut off the power supply branch 10, that is, set the melting time of the first fuse FU1 to be less than the disconnection time of the first relay J1 to avoid overload and improve the safety performance of the energy storage system.

[0034] In addition, if the fault current of the power supply branch 10 is greater than the third current and less than the first current, although the first fuse FU1 is not blown, the power supply branch 10 is faulty at this time. In order to avoid the energy storage system from operating when there is a fault in the power supply branch 10, and because the probability of the first relay J1 being stuck between the third current and the first current is low, the first relay J1 can be disconnected to ensure the safety of the battery pack 101 where the power supply branch 10 is located, thereby improving the safety performance of the energy storage system.

[0035] It can be understood that the first current in this embodiment is greater than or equal to the third current. If the first current is equal to the third current, the first fuse FU1 will be blown first. Although the coverage of global faults can be guaranteed, in order to reduce the number of replacements of the first fuse FU1, this application can set the first current to be greater than the third current.

[0036] In addition, when the power supply branch 10 uses the first relay J1 and the first fuse FU1 for full current range protection, the critical current used by the first relay J1 and the first fuse FU1 to cut off the power supply branch 10 can be less than the fourth current and greater than the first current.

[0037] It should be noted that when setting the critical current, it is necessary to ensure that the probability of the first relay J1 sticking is low when the first relay J1 reaches the disconnection condition, and to minimize the number of replacements of the first fuse FU1. This not only ensures the coverage of global faults of the energy storage system and improves the safety performance of the energy storage system, but also reduces the maintenance cost of the energy storage system.

[0038] In some implementations, as shown in FIG1 , each battery pack includes a second fuse FU2 and at least one battery cell, and the second fuse FU2 and the at least one battery cell are connected in series and are respectively connected to the input and output terminals of the battery pack;

[0039] Alternatively, each battery pack 101 includes at least one second fuse FU2 and at least one battery cell, and the second fuse FU2 and the battery cell are connected in series one by one and are electrically connected to the input end and the output end respectively to achieve parallel connection;

[0040] The fusing current of the second fuse FU2 is greater than or equal to a preset fifth current and less than or equal to a preset sixth current; wherein the fifth current is less than or equal to the fourth current and greater than or equal to the first current.

[0041] In this embodiment, by setting a second fuse FU2 in the battery pack 101, when a short circuit occurs in the battery pack 101, the second fuse FU2 can be used to promptly cut off the circuit where the battery pack 101 is located to ensure the safety of the battery pack 101. At the same time, this application also sets the melting current of the second fuse FU2 to be greater than or equal to the preset fifth current and less than or equal to the preset sixth current. The fifth current is less than the fourth current and greater than the first current, thereby avoiding the second fuse FU2 from melting earlier than the first fuse FU1. Therefore, when the fuse of the power supply branch 10 is replaced subsequently, the number of replacement times of the second fuse FU2 is reduced, thereby reducing the number of times the battery pack 101 is disassembled and assembled, greatly improving the maintenance efficiency of the energy storage system and reducing the maintenance cost of the energy storage system.

[0042] In addition, when the fifth current is equal to the fourth current and the fifth current is equal to the first current, the first fuse FU1 and the second fuse FU2 in the same power supply branch 10 both meet the conditions for melting. At this time, in order to avoid increasing the number of times the battery pack 101 is disassembled and assembled due to replacing the second fuse FU2, it is necessary to set the melting speed of the first fuse FU1 to be greater than the melting speed of the second fuse FU2.

[0043] In some implementations, as shown in FIG4 , in the power supply branch 10 , the fusing speed of the first fuse FU1 is greater than the fusing speed of the second fuse FU2 .

[0044] In this embodiment, by setting the melting speed of the first fuse FU1 to be greater than the melting speed of the second fuse FU2, after both the first fuse FU1 and the second fuse FU2 meet the melting conditions, the first fuse FU1 can be blown first and the second fuse FU2 is not blown, thereby avoiding increasing the number of times the battery pack 101 is disassembled and assembled due to replacing the second fuse FU2. At the same time, when the second fuse FU2 is blown between the fifth current and the sixth current, the fifth current can be greater than the critical current between the first relay J1 and the first fuse FU1, and thus, when both the first relay J1 and the first fuse FU1 fail, the second fuse FU2 can be used to cut off the power supply branch 10, thereby improving the safety of the energy storage system.

[0045] In some implementations, as shown in FIG1 , the power supply branch 10 includes a plurality of battery packs 101 , and the plurality of battery packs 101 are connected in series.

[0046] In this embodiment, by setting multiple battery packs 101 in each power supply branch 10, each battery pack 101 can also be connected in series with a fuse and / or a relay, which can not only increase the voltage of the power supply branch 10, but also enhance the safety performance of the power supply branch 10.

[0047] In some implementations, as shown in Figure 1, the high-voltage box 102 also includes a third fuse FU3; wherein, the first fuse FU1 and the first relay J1 are arranged between the first interface B+ and the third interface P+, ​​and the third fuse FU3 is arranged between the second interface B- and the fourth interface P-; or the first fuse FU1 and the first relay J1 are arranged between the second interface B- and the fourth interface P-, and the third fuse FU3 is arranged between the first interface B+ and the third interface P+; the third fusing current of the third fuse FU3 is greater than or equal to the first current, and less than or equal to the second current.

[0048] In this embodiment, fuses are provided on both the high side and the low side of the high-voltage box 102, thereby ensuring that whether a short circuit fault occurs on the high side of the high-voltage box 102 or a short circuit fault occurs on the low side of the high-voltage box 102, the circuit of the power supply branch 10 can be cut off by the fuse to ensure the safety of the energy storage system.

[0049] In some implementations, as shown in FIG1 , the high-voltage box 102 further includes a second relay J2; wherein the first fuse FU1 and the first relay J1 are arranged between the first interface B+ and the third interface P+, ​​and the third fuse FU3 and the second relay J2 are arranged between the second interface B- and the fourth interface P-; the second disconnection current of the second relay J2 is greater than or equal to the third current, and less than or equal to the fourth current.

[0050] Specifically, fuses and relays are provided on both the high side and the low side of the high-voltage box 102, which can further form complete short-circuit protection for the power supply branch 10, thereby further improving the safety performance of the energy storage system.

[0051] In some implementations, as shown in FIG1 , the target device in the energy storage system may be a power conversion system (PCS). The power storage converter 20 may control the charging and discharging process of the power supply branch 10 and perform AC / DC conversion. Furthermore, the PCS may directly power AC loads in the absence of a power grid.

[0052] In some implementations, as shown in FIG1 , the energy storage system includes multiple power supply branches 10 and load switches 30 ; wherein, after the multiple power supply branches 10 are connected in parallel, they are electrically connected to the energy storage converter 20 through the load switch 30 .

[0053] Specifically, one end of the load switch 30 is electrically connected to the third port P+ and the fourth port P− of the high-voltage box 102 in each power supply branch 10 , and the other end of the load switch 30 is electrically connected to the energy storage converter 20 .

[0054] In this embodiment, a load switch 30 is provided between the energy storage inverter 20 and the high-voltage box 102. When the relay in the high-voltage box 102 and / or the relay in the battery pack 101 cannot be disconnected, the load switch 30 can be used to disconnect the main circuit of the energy storage system, thereby further ensuring the safety performance of the energy storage system.

[0055] In some implementations, when the current of the power supply branch 10 is greater than or equal to a preset seventh current and less than or equal to a preset eighth current, the energy storage converter 20 controls the battery pack 101 in the power supply branch 10 to stop charging and / or stop discharging; wherein the eighth current is less than or equal to the fourth current.

[0056] In this embodiment, when the current of the power supply branch 10 is greater than or equal to the preset seventh current and less than or equal to the preset eighth current, a short circuit fault occurs in the power supply branch 10, and the current of the power supply branch 10 is the fault current. To improve the life of the first relay J1 in the high-voltage box 102 and prevent the first relay J1 from being unable to disconnect due to excessive current sticking, the energy storage converter 20 can be used to control the battery pack 101 in the power supply branch 10 to stop charging and / or discharging.

[0057] At the same time, the seventh current can be 210A, and the eighth current can be used as the critical current between the first relay J1 and the first fuse FU1, that is, it can be 3200A. Then, the first relay J1 and the first fuse FU1 can be used to achieve global fault coverage of the energy storage system.

[0058] In addition, when the current of the power supply branch 10 is greater than the eighth current, the first fuse FU1 in the high-voltage box 102 of the power supply branch 10 needs to be blown, and the first relay J1 in the high-voltage box 102 of other power supply branches 10 needs to be disconnected to put the energy storage system in standby state.

[0059] In some implementations, when the energy storage converter 20 controls the battery pack 101 in the power supply branch 10 to stop charging and / or discharging, if the current of the main circuit of the energy storage system is not the preset current, the load switch 30 is disconnected to cut off the main circuit of the energy storage system.

[0060] In this embodiment, after the energy storage converter 20 controls the battery pack 101 in the power supply branch 10 to stop charging or discharging, the main circuit of the energy storage system is usually in a cut-off state. In order to avoid the situation where the main circuit of the energy storage system is not cut off, after the energy storage converter 20 controls the battery pack 101 in the power supply branch 10 to stop charging or discharging, it can be determined whether the main circuit of the energy storage system is in a cut-off state by detecting whether the current of the main circuit of the energy storage system is a preset current. If the current of the main circuit of the energy storage system is the preset current, then it can be determined that the main circuit of the energy storage system is in a cut-off state; if the current of the main circuit of the energy storage system is not the preset current, then it can be determined that the main circuit of the energy storage system is in an uncut-off state, and then a load switch 30 needs to be used to cut off the main circuit of the energy storage system.

[0061] At the same time, in order to avoid directly cutting off the load switch 30 before the main circuit is discharged, the present application can also delay the cutting off of the load switch 30 for a preset time, wherein the preset current can be zero current, and the preset time can be 3s, 4s, etc.

[0062] In some implementations, after the energy storage converter 20 controls the battery pack 101 in the power supply branch 10 to stop charging and / or discharging, if the current of the main circuit of the energy storage system is not a preset current and the load switch 30 is not disconnected, the first relay J1 in the power supply branch 10 is disconnected.

[0063] Specifically, in order to avoid the situation where the current in the main circuit of the energy storage system is not the preset current and the load switch 30 is not disconnected after the energy storage inverter 20 controls the battery pack 101 in the power supply branch 10 to stop charging or / and stop discharging, the present application can also force the first relay J1 in the power supply branch 10 to be cut off to provide safety protection for the battery pack 101 in the energy storage system.

[0064] It should be noted that when controlling the first relay J1 in the power supply system to be disconnected, it is necessary to at least control the first relay J1 in the power supply branch 10 where the fault current occurs to be disconnected.

[0065] That is, after the energy storage converter 20 controls the battery pack 101 in the power supply branch 10 to stop charging and / or discharging, if the current in the main circuit of the energy storage system is not the preset current and the load switch 30 is not disconnected, the first relays J1 in all power supply branches 10 in the energy storage system may be disconnected, or the first relays J1 in some power supply branches 10 in the energy storage system may be disconnected. The some power supply branches 10 include the power supply branch 10 that has a fault.

[0066] In some implementations, as shown in FIG1 , the load switch 30 includes a trip unit TK; wherein the trip unit TK is configured to cut off the main circuit of the energy storage system.

[0067] The present application utilizes a trip device TK within the load switch 30 to disconnect the main circuit of the energy storage system. When there is a line leakage or a person is electrocuted, the trip device TK generates a voltage across the transformer's secondary coil when the vector sum of the currents flowing through the zero-sequence current transformer is not equal to zero. This voltage is amplified by an integrated circuit and, when the voltage reaches a set value, is rapidly disconnected via the leakage trip device TK, thereby providing protection against electric shock and leakage.

[0068] In related technologies, energy storage systems are equipped with fuses in the high-voltage box, battery rack, and combiner cabinet. When a fault occurs in the high-voltage box or combiner cabinet, the fuses in the high-voltage box blow, disconnecting the high-voltage circuit and providing protection. However, this approach cannot protect the energy storage system against the full range of fault currents, reducing the safety of the energy storage system circuit and increasing the difficulty and cost of maintenance.

[0069] To this end, in some implementations, as shown in FIG2 , this application further provides a method for protecting an energy storage system. The method is performed by an electrical device or a control module within the electrical device. The control module may be a battery management system (BMS), a vehicle control unit (VCU), or the like.

[0070] The following embodiments of the present application are described in detail using a battery management system as an example.

[0071] Referring to FIG. 1 and FIG. 2 , the energy storage system includes at least one power supply branch 10 ; wherein the power supply branch 10 includes a high-voltage box 102 , which includes a first fuse FU1 and a first relay J1 . The circuit protection method of the energy storage system includes:

[0072] S101 : When it is detected that the fault current of the power supply branch 10 is less than or equal to a preset critical current, a cut-off instruction is sent to the first relay J1 to disconnect the power supply branch 10 .

[0073] The energy storage system includes at least one power supply branch 10 , the power supply branch 10 includes a high-voltage box 102 , and the high-voltage box 102 includes a first fuse FU1 and a first relay J1 .

[0074] The critical current is a preset threshold current, such as 3200 A, configured to determine whether the fault current of power supply branch 10 in the energy storage system is too high. The fault current is the current detected by the battery management system upon receiving a signal indicating a short circuit fault in power supply branch 10 in the energy storage system. For example, the fault current of power supply branch 10 is greater than or equal to 210 A.

[0075] In this embodiment, when the battery management system receives a signal indicating a short circuit fault in the energy storage system, if it detects that the fault current of the power supply branch 10 is less than or equal to the critical current, it can send a cut-off instruction to the first relay J1 in the high-voltage box 102 of the power supply branch 10, control the first relay J1 to disconnect the power supply branch 10, and control the first relay J1 to cut off the circuit of the energy storage system under load, that is, control the first relay J1 to forcibly cut off, thereby avoiding the appearance of a high-voltage load in the circuit of the energy storage system and ensuring that the first relay J1 covers the minimum breaking current of the first fuse FU1, avoiding the problem that when the fault current of the power supply branch 10 is less than or equal to the critical current, the first relay J1 will cause adhesion due to exceeding the tolerance time and the high-voltage load will be destroyed due to long-term overload.

[0076] It should be noted that when the battery management system detects that the fault current of the power supply branch 10 is less than or equal to the critical current, it can directly send a cut-off instruction to the first relay J1 in the high-voltage box 102 to achieve forced cutting of the first relay J1 in the power supply branch 10. Compared with the traditional method of sending a charge and discharge prohibition instruction to the target device (such as the energy storage inverter 20), that is, by cutting off the power to the target device, it may be possible to return to the situation where the target device cannot be powered off. In this embodiment, by controlling the first relay J1 to force cut off, that is, controlling the first relay J1 to disconnect the power supply branch 10, it is achieved to control the first relay J1 to cut off the circuit of the energy storage system under load, thereby avoiding the occurrence of high-voltage load in the energy storage system.

[0077] It should also be noted that, in actual application scenarios, the fault current of the power supply branch 10 may contain spikes, which may lead to misjudgment of the fault current detection. Therefore, when it is detected that the fault current of the power supply branch 10 is less than or equal to the critical current, a preset time can be set for delayed disconnection. If the fault current is still less than or equal to the critical current after the preset time, a disconnection command is sent to the first relay J1 in the high-voltage box 102 to prevent misjudgment of the fault current. The preset time can be 3 seconds, 4 seconds, etc.

[0078] S102 : When the fault current is greater than the critical current, the first fuse FU1 is blown to disconnect the power supply branch 10 .

[0079] Specifically, when the battery management system detects that the fault current of the power supply branch 10 is greater than the critical current, the first fuse FU1 in the high-voltage box 102 automatically blows, that is, the first fuse FU1 in the high-voltage box 102 is disconnected first, thereby disconnecting the power supply branch 10, and then disconnecting the circuit of the energy storage system, thereby protecting the energy storage system. In addition, the first fuse FU1 is disconnected before the first relay J1, and there is no need to disconnect the first relay J1, thereby avoiding adhesion of the first relay J1, thereby protecting the battery pack 101, high-voltage load and first relay J1 of the energy storage system, avoiding the replacement of the battery pack 101, facilitating the maintenance of the energy storage system, and improving the safety of the energy storage system.

[0080] It can be understood that when the present application detects that the fault current of the power supply branch 10 is greater than the critical current, the first fuse FU1 is blown first compared to the fuse in the battery pack 101. This can avoid increasing the number of times the battery pack 101 is disassembled and assembled due to replacing the fuse in the battery pack 101, thereby reducing the maintenance cost and difficulty caused by replacing the battery pack 101, and protecting the energy storage system to the greatest extent.

[0081] In this embodiment, when it is detected that the fault current of the power supply branch 10 is less than or equal to the critical current, a cut-off instruction can be sent to the first relay J1 to disconnect the power supply branch 10; when the fault current is greater than the critical current, the first fuse FU1 is blown to disconnect the power supply branch 10, thereby achieving current matching between the first relay J1 and the first fuse, thereby ensuring that the first relay J1 and the first fuse FU1 can protect the energy storage system under the full range of fault currents, avoiding the situation where the first relay J1 in the high-voltage box 102 cannot be disconnected and the first fuse cannot be blown when a fault current occurs in the power supply branch 10.

[0082] It can be understood that this embodiment adopts corresponding disconnection methods based on the two comparison results between the fault current and the critical current of the power supply branch 10, thereby achieving loop disconnection protection for the energy storage system under the full range of fault currents, protecting the energy storage system to the greatest extent, facilitating the maintenance of the energy storage system, and improving the safety of the energy storage system.

[0083] In the circuit protection method for the energy storage system provided in the present application, when it is detected that the fault current of the power supply branch 10 is less than or equal to the critical current, the first relay J1 in the high-voltage box 102 is cut off, and the first relay J1 is controlled to disconnect the power supply branch 10, thereby controlling the first relay J1 to cut off the circuit of the energy storage system under load; when the fault current of the power supply branch 10 is greater than the critical current, the first fuse FU1 is blown first to cut off the circuit of the energy storage system, thereby achieving current matching between the first relay J1 and the first fuse FU1, and thereby ensuring that the first relay J1 and the first fuse FU1 achieve circuit disconnection protection of the energy storage system under the full range of fault currents, thereby protecting the energy storage system to the greatest extent, facilitating the maintenance of the energy storage system, and improving the safety of the energy storage system.

[0084] In some implementations, the critical current may be a peak current of the first relay J1 .

[0085] In this embodiment, the critical current is the peak current of the first relay J1. Therefore, when the fault current value of the power supply branch 10 is greater than the peak current of the first relay J1, it indicates that the fault current is too large. At this time, the first fuse FU1 in the high-voltage box 102 is blown before the second fuse FU2 in the battery pack 101, thereby disconnecting the power supply branch 10 and protecting the battery pack 101, the first relay J1, and the high-voltage load of the energy storage system. When the fault current value of the power supply branch 10 is less than the peak current of the first relay J1, it indicates that the fault current is small and the first fuse FU1 takes a longer time to blow. At this time, the battery management system controls the first relay J1 to be disconnected, and controls the first relay J1 to be forced to cut.

[0086] In some implementations, as shown in Figure 1, the energy storage system includes an energy storage converter 20, and the power supply branch 10 is electrically connected to the energy storage converter 20. The loop protection method of the energy storage system also includes: when it is detected that the fault current of the power supply branch 10 is less than or equal to the critical current, a charge and discharge prohibition instruction is sent to the energy storage converter 20; if it is detected that the power of the energy storage converter 20 is less than or equal to a first preset value and the current of the loop of the energy storage system is less than or equal to a second preset value, it is determined that the power supply branch 10 is disconnected.

[0087] The "discharge and charge prohibition instruction" refers to an operational command that controls the energy storage converter 20 through the battery management system to disconnect the power supply branch 10. The first preset value represents the maximum power value of the energy storage converter 20 when the power supply branch 10 is disconnected. For example, the first preset value may be 0W (watts), 0.5W, etc. The second preset value represents the maximum current value of the energy storage system circuit when the power supply branch 10 is disconnected. For example, the second preset value may be 0A, 0.1A, etc.

[0088] Specifically, when the fault current is less than or equal to the critical current, the battery management system sends a charge and discharge prohibition instruction to the energy storage inverter 20. In order to detect whether the energy storage inverter 20 responds to the charge and discharge prohibition instruction, it can be detected based on the power of the energy storage inverter 20 and the current of the energy storage system loop. When it is detected that the power of the energy storage inverter 20 is less than or equal to the first preset value and the current of the energy storage system loop is less than or equal to the second preset value, it indicates that the power of the energy storage inverter 20 has dropped below the first preset value, and it also indicates that the current of the energy storage system loop has decreased below the second preset value. At this time, it can be determined that the power supply branch 10 is disconnected, that is, the energy storage inverter 20 responds to the charge and discharge prohibition instruction.

[0089] It can be understood that in this embodiment, when the fault current of the power supply branch 10 is less than or equal to the critical current, the power supply branch 10 is disconnected by controlling the energy storage converter 20 to prohibit charging and discharging, thereby disconnecting the circuit of the energy storage system. This can enhance the protection of the energy storage system, reduce the frequency of load disconnection of the first relay J1, and increase the service life of each electrical component.

[0090] In some implementations, as shown in Figure 1, a load switch 30 is provided between the energy storage inverter 20 and the power supply branch 10, and the loop protection method of the energy storage system also includes: if it is detected that within a first preset time, the power of the energy storage inverter 20 is greater than a first preset value and the current of the loop of the energy storage system is greater than a second preset value, the load switch 30 is controlled to disconnect to disconnect the power supply branch 10.

[0091] The first preset time is configured to prevent misjudgment of whether the energy storage converter 20 responds to the charge and discharge prohibition instruction. For example, the first preset time may be 3 seconds, 4 seconds, etc.

[0092] Specifically, in order to ensure the stability of the detected power of the energy storage inverter 20 and the current of the energy storage system loop and avoid misjudgment, the present application can perform detection within a first preset time. If it is detected that the power of the energy storage inverter 20 is greater than the first preset value and the current of the energy storage system loop is greater than the second preset value, it indicates that the power of the energy storage inverter 20 is above the first preset value and the current of the energy storage system loop is above the second preset value. It can be determined that the power supply branch 10 is connected, that is, the energy storage inverter 20 does not respond to the charge and discharge prohibition instruction, that is, controlling the energy storage inverter 20 to prohibit charging and discharging and disconnect the power supply branch 10 fails. At this time, the battery management system controls the load switch 30 to disconnect to disconnect the power supply branch 10.

[0093] It can be understood that in this embodiment, by providing a load switch 30 between the energy storage converter 20 and the power supply branch 10, when the battery management system fails to control the energy storage converter 20 to prohibit charging and discharging and disconnect the power supply branch 10, the load switch 30 is used to disconnect the power supply branch 10, thereby strengthening the protection of the energy storage system, reducing the frequency of load disconnection of the first relay J1, and increasing the service life of each electrical component.

[0094] In some implementations, controlling the load switch 30 to be disconnected specifically includes: after a predetermined delay, sending a tripping instruction to the load switch 30 to control the load switch 30 to be disconnected.

[0095] The tripping instruction is an operation command to disconnect the power supply branch 10 by controlling the load switch 30 to trip. The predetermined time is a preset time configured to prevent misjudgment of whether the power supply branch 10 is disconnected. The predetermined time can be 3 seconds, 4 seconds, etc.

[0096] Specifically, after a predetermined time, a tripping instruction can be sent to the load switch 30 through the battery management system to control the load switch 30 to perform tripping, so as to protect the energy storage system by controlling the load switch 30, reduce the frequency of load disconnection of the high-voltage relay, and increase the service life of each electrical component.

[0097] In some implementations, the circuit protection method for the energy storage system further includes: if it is detected that the load switch 30 does not respond to the tripping instruction within the second preset time, sending a disconnection instruction to the first relay J1 to disconnect the power supply branch 10.

[0098] The second preset time is a time set in advance to prevent misjudgment of whether the load switch 30 responds to the tripping instruction. The second preset time may be 3 seconds, 4 seconds, or the like.

[0099] Specifically, when it is detected that the load switch 30 does not respond to the tripping instruction within the second preset time, that is, the load switch 30 is not disconnected, in order to disconnect the power supply branch 10, the battery management system sends a disconnection instruction to the first relay J1 to disconnect the power supply branch 10, so as to achieve forced disconnection of the power supply branch 10 by controlling the first relay J1, thereby protecting the energy storage system and improving the safety of the energy storage system.

[0100] In some implementations, as shown in FIG3 , the present application provides a circuit protection method for an energy storage system, the method specifically comprising the following steps:

[0101] When it is detected that the fault current of the power supply branch 10 is less than or equal to the critical current, a cut-off instruction is sent to the first relay J1 to disconnect the power supply branch 10;

[0102] When it is detected that the fault current of the power supply branch 10 is less than or equal to the critical current, a charge and discharge prohibition instruction is sent to the energy storage converter 20. If it is detected that the power of the energy storage converter 20 is less than or equal to the first preset value and the current of the energy storage system loop is less than or equal to the second preset value, it is determined that the power supply branch 10 is disconnected;

[0103] If it is detected that the power of the energy storage converter 20 is greater than a first preset value and the current of the energy storage system circuit is greater than a second preset value within a first preset time, the load switch 30 is controlled to be disconnected to disconnect the power supply branch 10; wherein, controlling the load switch 30 to be disconnected to disconnect the power supply branch 10 specifically includes: after a predetermined delay, sending a tripping instruction to the load switch 30 to control the load switch 30 to be disconnected to disconnect the power supply branch 10;

[0104] If it is detected that the load switch 30 does not respond to the tripping instruction within the second preset time, a cut-off instruction is sent to the first relay J1 to disconnect the power supply branch 10;

[0105] When the fault current is greater than the critical current, the first fuse FU1 is blown to disconnect the power supply branch 10 .

[0106] Specifically, the fault current is greater than or equal to 210A, the critical current is 3200A, the first preset time is 3 seconds, the second preset time is 3 seconds, the predetermined time is 3 seconds, the first preset value is 0W, and the second preset value is 0A. FIG3 is another flow chart of the circuit protection method for the energy storage system in this example.

[0107] In some implementations, the energy storage system includes a first power supply branch and a second power supply branch connected in parallel, and the circuit protection method of the energy storage system further includes: if it is detected that the fault current of the first power supply branch is less than or equal to the critical current, sending a disconnection instruction to the first relay J1 in the high-voltage box 102 of the first power supply branch to disconnect the corresponding first power supply branch; and / or,

[0108] If the fault current of the second power supply branch is greater than the critical current, the first fuse FU1 in the high-voltage box 102 of the second power supply branch is blown to disconnect the corresponding second power supply branch.

[0109] Specifically, the energy storage system includes a first power supply branch and a second power supply branch connected in parallel. The circuit protection methods of the energy storage system may include the following situations:

[0110] The first situation: the fault current of the first power supply branch is less than or equal to the critical current, and the battery management system sends a cut-off command to the first relay J1 in the high-voltage box 102 of the first power supply branch to disconnect the corresponding first power supply branch, or the fault current of the second power supply branch is greater than the critical current, and the first fuse FU1 in the high-voltage box 102 of the second power supply branch melts to disconnect the corresponding second power supply branch.

[0111] The second situation: the fault current of the first power supply branch is less than or equal to the critical current, and the battery management system sends a cut-off command to the first relay J1 in the high-voltage box 102 of the first power supply branch to disconnect the corresponding first power supply branch. In addition, the fault current of the second power supply branch is greater than the critical current, and the first fuse FU1 in the high-voltage box 102 of the second power supply branch melts to disconnect the corresponding second power supply branch.

[0112] It should be noted that, when the fault current of the first power supply branch is less than or equal to the critical current, and the fault current of the second power supply branch is less than or equal to the critical current, the battery management system sends a cut-off instruction to the first relay J1 in the high-voltage box 102 of the first power supply branch to disconnect the corresponding first power supply branch. At the same time, the battery management system also sends a cut-off instruction to the first relay J1 in the high-voltage box 102 of the second power supply branch to disconnect the corresponding second power supply branch; when the fault current of the first power supply branch is greater than the critical current, and the fault current of the second power supply branch is greater than the critical current, the first fuse FU1 in the high-voltage box 102 of the first power supply branch is blown to disconnect the corresponding first power supply branch. At the same time, the first fuse FU1 in the high-voltage box 102 of the second power supply branch is blown to disconnect the corresponding second power supply branch.

[0113] It can be understood that since the first power supply branch and the second power supply branch are connected in parallel, in order to achieve comprehensive protection of the energy storage system, in this embodiment, the first power supply branch and the second power supply branch are disconnected according to the magnitude of the fault current, respectively, through the corresponding power supply branch disconnection method, thereby achieving disconnection protection for multiple power supply branches, and thus comprehensively protecting the energy storage system.

[0114] In some implementations, as shown in FIG1 , the energy storage system includes a plurality of power supply branches 10 connected in parallel, and the circuit protection method of the energy storage system further includes: if the fault current of at least one power supply branch 10 is greater than the critical current, the first fuse FU1 in the high-voltage box 102 of the corresponding power supply branch 10 is blown to disconnect the corresponding power supply branch 10; and a disconnection instruction is sent to the first relay J1 in the other power supply branches 10 to disconnect all power supply branches 10.

[0115] Specifically, the energy storage system includes multiple power supply branches 10 connected in parallel. For a power supply branch 10 whose fault current is greater than the critical current, the first fuse FU1 in the high-voltage box 102 of the power supply branch is blown to disconnect the corresponding power supply branch 10; for other power supply branches 10 whose fault current is less than or equal to the critical current, the battery management system sends a disconnection instruction to the first relay J1 in the other power supply branches 10 to disconnect all power supply branches, thereby achieving disconnection protection for all power supply branches 10, and thereby comprehensively protecting the energy storage system.

[0116] In some implementations, please refer to Figure 4, which shows the melting time of the first fuse FU1 in the high-voltage box 102 in the power supply branch and the second fuse FU2 in the battery pack 101 under different currents, as well as the tolerance time of the first relay J1 in the high-voltage box 102 under different currents.

[0117] As can be seen from Figure 4, if the critical current is 3200A, when the fault current is ≤3200A, the sectional disconnection capacity of the first fuse FU1 and the second fuse FU2 in the battery pack 101 is not reached. The first relay J1, through the battery management system control, realizes the protection capability of the load disconnection circuit after 6 seconds. When the fault current is greater than 3200A, the melting time of the second fuse FU2 in the battery pack 101 (0.18 seconds) is greater than the melting time of the first fuse FU1 (0.018 seconds), and the first fuse FU1 melts first, thereby achieving protection for the battery pack 101 and the high-voltage box 102.

Claims

1. An energy storage system, comprising at least one power supply branch each comprising:at least one battery pack, each comprising an input and an output;a high-voltage box comprising a first interface, a second interface, a third interface and a fourth interface, wherein the first interface is electrically connected to the input end of one battery pack, the second interface is electrically connected to the output end of the battery pack, and the third interface and the fourth interface are electrically connected to a target device;wherein the high-voltage box further comprises a first fuse and a first relay, wherein the first fuse and the first relay are arranged between the first interface and the third interface, or the first fuse and the first relay are arranged between the second interface and the fourth interface; andwherein a fusing current of the first fuse is greater than or equal to a preset first current and is less than or equal to a preset second current; a disconnecting current of the first relay is greater than or equal to a preset third current and is less than or equal to a preset fourth current; the fourth current is greater than or equal to the first current and is less than the second current.

2. The energy storage system according to claim 1, wherein when a fault current of one power supply branch is greater than or equal to the first current and is less than the fourth current, a fusing time of the first fuse is less than a disconnection time of the first relay.

3. The energy storage system according to claim 1, wherein each battery pack comprises a second fuse and at least one battery cell, wherein the second fuse and the at least one battery cell are connected in series and are respectively connected to the input end and the output end; orwherein each battery pack comprises at least one second fuse and at least one battery cell, wherein the at least one second fuse and the at least one battery cell are connected in one-to-one correspondence with each other in series and electricallyconnected to the input end and the output end of the battery pack respectively to achieve a parallel connection;a fusing current of the second fuse is greater than or equal to a preset fifth current and is less than or equal to a preset sixth current; the fifth current is less than or equal to the fourth current and greater than or equal to the first current.

4. The energy storage system according to claim 3, wherein in each power supply branch, a fusing speed of the first fuse is greater than a fusing speed of the second fuses.

5. The energy storage system according to claim 1, wherein the high-voltage box further comprises a third fuse;wherein the first fuse and the first relay are arranged between the first interface and the third interface, and the third fuse is arranged between the second interface and the fourth interface; or the first fuse and the first relay are arranged between the second interface and the fourth interface, and the third fuse is arranged between the first interface and the third interface;wherein a fusing current of the third fuse is greater than or equal to the first current and is less than or equal to the second current.

6. The energy storage system according to claim 5, wherein the high-voltage box further comprises a second relay;wherein the first fuse and the first relay are arranged between the first interface and the third interface, and the third fuse and the second relay are arranged between the second interface and the fourth interface;wherein a disconnecting current of the second relay is greater than or equal to the third current and is less than or equal to the fourth current.

7. The energy storage system according to any one of claims 1 to 6, wherein the number of the at least one battery pack is at least two, wherein the at least two of battery packs are connected in series.

8. The energy storage system according to any one of claims 1 to 6, wherein the target device is a power conversion system (PCS);when a current of one power supply branch is greater than or equal to a preset seventh current and is less than or equal to a preset eighth current, the PCS controls one or more of the at least one battery pack in the power supply branch to stop charging and / or stop discharging; wherein the eighth current is less than or equal to the fourth current.

9. The energy storage system according to claim 8, wherein the energy storage system comprises a load switch, wherein the number of the at least one power supply branch is at least two;wherein, after the at least two power supply branches are connected in parallel, and are electrically connected to the PCS by the load switch.

10. The energy storage system according to claim 9, wherein the load switch comprises a tripper configured to cut off a main circuit of the energy storage system.

11. The energy storage system according to claim 9, wherein after the PCS controls the battery pack in the power supply branch to stop charging and / or stop discharging, if a current of a main circuit of the energy storage system is not a preset current, the load switch is disconnected to cut off the main circuit of the energy storage system.

12. The energy storage system according to claim 11, wherein after the PCS controls the battery pack in the power supply branch to stop charging and / or stop discharging, if the current of the main circuit of the energy storage system is not the preset current and the load switch is not disconnected, the first relay in the power supply branch is disconnected.

13. A circuit protection method for an energy storage system, wherein the energy storage system comprises at least one power supply branch each comprising a high-voltage box that comprises a first fuse and a first relay, wherein the circuit protection method comprises:when detecting that a fault current of one power supply branch is less than or equal to a preset critical current, sending a disconnection instruction to the first relay of the power supply branch to disconnect the power supply branch; andwhen the fault current is greater than the critical current, fusing the first fuse of the power supply branch to disconnect the power supply branch.

14. The circuit protection method for the energy storage system according to claim 13, wherein the critical current is a peak current of the first relay.

15. The circuit protection method for the energy storage system according to claim 13, wherein the energy storage system comprises a power conversion system (PCS), wherein the at least one power supply branch is electrically connected to the PCS, and wherein the circuit protection method further comprises:sending a charge and discharge prohibition instruction to the PCS when detecting that the fault current of the power supply branch is less than or equal to the critical current;determining that the power supply branch is disconnected if detecting that a power of the PCS is less than or equal to a first preset value and that a current of a circuit of the energy storage system is less than or equal to a second preset value.

16. The circuit protection method for the energy storage system according to claim 15, wherein a load switch is provided between the PCS and the at least one power supply branch, wherein the circuit protection method further comprises:controlling the load switch to be disconnected to disconnect the power supply branch if detecting that, in a first preset time, the power of the PCS is greater than the first preset value and that the current of the circuit of the energy storage system is greater than the second preset value.

17. The circuit protection method for the energy storage system according to claim 16, wherein the controlling the load switch to disconnect comprises:after a delay of predetermined time, sending a tripping instruction to the load switch to control the load switch to disconnect.

18. The circuit protection method for the energy storage system according to claim 17, wherein the circuit protection method further comprises:sending a disconnection instruction to the first relay to disconnect the powersupply branch if detecting that the load switch does not respond to the tripping instruction within a second preset time.

19. The circuit protection method for the energy storage system according to any one of claims 13 to 18, wherein the energy storage system comprises a first power supply branch and a second power supply branch that are connected in parallel, wherein the circuit protection method further comprises:sending a disconnection instruction to the first relay in the high-voltage box of the first power supply branch to disconnect the first power supply branch if detecting that a fault current of the first power supply branch is less than or equal to the critical current; and / orfusing the first fuse in the high-voltage box of the second power supply branch to disconnect the second power supply branch if a fault current of the second power supply branch is greater than the critical current.

20. The circuit protection method for the energy storage system according to any one of claims 13 to 18, wherein the number of the at least one power supply branch is at least two, and the at least two power supply branches are connected in parallel, wherein the circuit protection method further comprises:if a fault current of each of one or more of the at least two power supply branches is greater than the critical current, fusing the first fuse in the high-voltage box of each of the one or more of the at least two power supply branches to disconnect the one or more of the at least two power supply branches; andsending a disconnection instruction to the first relay in each of all other ones of the at least two power supply branches to disconnect all of the at least two power supply branches in the energy storage system.

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