Energy storage system and protection method for energy storage system

Abstract

The present application provides an energy storage system, and a protection method for an energy storage system. The energy storage system comprises at least one power supply branch, the power supply branch comprising at least one battery pack and a high-voltage box. A breaking current of a first switch in the high-voltage box is greater than or equal to a first current, and a first breaking current of a first fuse in the high-voltage box is less than or equal to a second current, the first current being less than or equal to the second current, and a breaking speed of the first switch being greater than a breaking speed of the first fuse.

Description

Energy storage system and protection method of energy storage system

[0001] The present application claims priority to the Chinese patent application No. 202410858989.3, filed on June 28, 2024, to the Chinese Patent Office, the whole content of the above application being incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to an energy storage system and a protection method of the energy storage system. BACKGROUND

[0003] When a short circuit occurs in the energy storage system, the lithium battery and other elements in the energy storage system are greatly damaged, therefore, the selection of the protection device in the energy storage system is particularly important, and the protection device is generally arranged in a high-voltage box to protect the energy storage system from short circuit. SUMMARY

[0004] However, the protection device in the high-voltage box has a protection blind area and cannot effectively protect the energy storage system.

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

[0006] at least one battery pack;

[0007] a high-voltage box, comprising: a first fuse and a first switch; the first fuse and the first switch are connected in series between a first interface and a third interface of the high-voltage box, or the first fuse and the first switch are connected in series between a second interface and a fourth interface of the high-voltage box; one end of the battery pack is electrically connected to the first interface, the other end of the battery pack is electrically connected to the second interface, and the third interface and the fourth interface are respectively electrically connected to a target device.

[0008] The breaking current of the first switch is greater than or equal to a preset first current, the first breaking current of the first fuse is less than or equal to a preset second current, the first current is less than or equal to the second current, and the breaking speed of the first switch is greater than the breaking speed of the first fuse.

[0009] In a second aspect, the present application further provides a protection method of an energy storage system, the energy storage system comprising: at least one power supply branch, the power supply branch comprising: at least one battery pack and a high-voltage box, the high-voltage box comprising: a first switch and a first fuse, the method comprising:

[0010] When it is detected that the fault current of the power supply branch is greater than or equal to a preset first current and less than a preset second current, a cut-off instruction is sent to the first switch to cut off the power supply branch.

[0011] When the fault current of the power supply branch is detected to be greater than or equal to the preset second current, the first fuse is fused to cut off the power supply branch. Advantages

[0012] The energy storage system provided in the application can use the first switch or the first fuse for protection when the fault current of the power supply branch of the energy storage system is between the first current and the second current, so as to avoid the problem of protection blind area, and preferentially use the first switch for breaking when the first switch and the first fuse both meet the breaking condition, so as to reduce the number of replacements of the first fuse and the maintenance cost of the energy storage system.

[0013] The protection method of the energy storage system provided in the application can send a cutting instruction to the first switch to cut off the power supply branch when the fault current of the power supply branch is detected to be greater than or equal to the preset first current and less than the preset second current, and the first fuse is fused to cut off the power supply branch when the fault current of the power supply branch is detected to be greater than or equal to the preset second current, so as to avoid the problem of protection blind area when the energy storage system is protected by the high-voltage box, realize the full-domain protection of the energy storage system, and greatly improve the safety performance of the energy storage system. BRIEF DESCRIPTION OF DRAWINGS

[0014] FIG. 1 is a protection range diagram of an energy storage system in the related art;

[0015] FIG. 2 is a schematic block diagram of an energy storage system provided in the application;

[0016] FIG. 3 is a protection range diagram of an energy storage system provided in the application;

[0017] FIG. 4 is a flow diagram of a protection method of an energy storage system provided in the application;

[0018] FIG. 5 is a flow diagram of a protection method of an energy storage system provided in the application;

[0019] FIG. 6 is another flow diagram of a protection method of an energy storage system provided in the application. Embodiments of the application

[0020] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0021] In the related art, the fuses and relays in the high-voltage box of the energy storage system adopt the protection range shown in FIG. 1 to protect the energy storage system from short circuit. As can be seen from FIG. 1, the energy storage system has a protection blind area. When the fault current of the power supply branch is less than 1kA (i.e. phase I), the relay in the high-voltage box is used to protect the energy storage system from short circuit; when the fault current of the power supply branch is greater than or equal to 1kA and less than or equal to 4kA (i.e. phase II), the energy storage system is not protected from short circuit; when the fault current of the power supply branch is greater than 4kA (i.e. phase III), the fuse in the high-voltage box is used to protect the energy storage system from short circuit. As can be seen, the protection devices in the high-voltage box cannot effectively protect the energy storage system.

[0022] To solve the technical problem that the protection devices in the high-voltage box cannot effectively protect the energy storage system, the present application provides an energy storage system, which can use the first switch K1 or the first fuse FU1 to protect when the fault current of the energy storage system is between the first current and the second current, and when the first switch K1 and the first fuse FU1 both satisfy the breaking condition, the first switch K1 is used to break preferentially, thereby reducing the number of replacements of the first fuse FU1 and reducing the maintenance cost of the energy storage system.

[0023] Please refer to FIG. 2, which is a schematic block diagram of the energy storage system provided by the present application. As shown in FIG. 1, an energy storage system comprises at least one power supply branch, which comprises:

[0024] at least one battery pack 10;

[0025] a high-voltage box 20, comprising a first fuse FU1 and a first switch K1; the first fuse FU1 and the first switch K1 are connected in series between a first interface and a third interface of the high-voltage box 20, or the first fuse FU1 and the first switch K1 are connected in series between a second interface and a fourth interface of the high-voltage box 20; the first interface is electrically connected to one end of the battery pack 10, the second interface is electrically connected to the other end of the battery pack 10, and the third interface and the fourth interface are respectively electrically connected to a target device;

[0026] The breaking current of the first switch K1 is greater than or equal to a preset first current, the first breaking current of the first fuse FU1 is less than or equal to a preset second current, the first current is less than or equal to the second current, and the breaking speed of the first switch K1 is greater than the breaking speed of the first fuse FU1.

[0027] In the embodiment, the first breaking current can be the minimum breaking current of the first fuse FU1, and the interval between the first current and the second current can be understood as a protection blind area of the energy storage system. In the application, the breaking current of the first switch K1 is greater than or equal to the first current, that is, the maximum breaking current of the first switch K1 is greater than or equal to the first current, the breaking current of the first fuse FU1 is less than or equal to the second current, and at the same time, the minimum breaking current of the first fuse FU1 is less than or equal to the second current. Therefore, after a short-circuit fault occurs in the energy storage system, if the fault current of the power supply branch of the energy storage system is between the first current and the second current, the first switch K1 or the first fuse FU1 can be used for breaking, so as to avoid the protection blind area. At the same time, when the first switch K1 and the first fuse FU1 both meet the breaking condition, the first switch K1 is preferentially used for breaking, so that the number of replacements of the first fuse FU1 can be reduced, and the maintenance cost of the energy storage system can be reduced.

[0028] In some embodiments, the first switch K1 includes a relay, and the first fuse FU1 and the relay are connected in series between the first interface and the third interface, or the first fuse FU1 and the relay are connected in series between the second interface and the fourth interface. The second breaking current of the relay is greater than or equal to the first current and less than or equal to the second current, and the breaking speed of the relay is greater than the breaking speed of the first fuse FU1.

[0029] In the embodiment, the first switch K1 can be a relay, and the second breaking current can be the maximum breaking current of the relay. The relay and the first fuse FU1 connected in series in the high-voltage box 20 can be used to protect the energy storage system. In order to avoid the protection blind area, the maximum breaking current of the relay needs to be greater than or equal to the first current (such as 1kA) and less than or equal to the second current (such as 4kA). Therefore, when the fault current of the power supply branch of the energy storage system is less than or equal to the second current, the relay can be used for protection, and when the fault current is greater than the second current, the first fuse FU1 can be used for protection, so that the protection blind area can be avoided.

[0030] In addition, the application can also set two groups of series-connected relays and first fuses FU1 in the high-voltage box 20. One group of relays and first fuses FU1 are connected in series between the first interface and the third interface, and the other group of relays and first fuses FU1 are connected in series between the second interface and the fourth interface.

[0031] In some embodiments, the second breaking current of the relay is less than or equal to the first breaking current of the first fuse FU1.

[0032] Specifically, the first breaking current can be the minimum breaking current of the first fuse FU1, and the second breaking current can be the maximum breaking current of the relay. Generally, during normal operation of the relay, if the fault current in the power supply branch is too large, the relay is prone to sticking. When the fault current in the power supply branch is between the first current and the second current, in order to reduce the probability of sticking of the relay, the second breaking current of the relay can be less than or equal to the minimum breaking current of the first fuse FU1, so that the relay can be used for breaking between the first current and the minimum breaking current of the first fuse FU1, and the first fuse FU1 can be used for breaking between the minimum breaking current of the first fuse FU1 and the second current.

[0033] In some embodiments, when the fault current in the power supply branch is equal to the second breaking current of the relay, the direct current time constant of the energy storage system is greater than or equal to a preset first time and less than or equal to a preset second time, and the relay breaks after a preset third time.

[0034] Specifically, in order to ensure that the fault current in the power supply branch is equal to the second breaking current of the relay, the relay can break at the maximum breaking current, the energy storage system provided by the present application also needs to meet certain conditions, that is, the direct current time constant of the energy storage system needs to be greater than or equal to a preset first time and less than or equal to a preset second time, wherein the first time can be 1 ms, and the second time can be 3 ms.

[0035] At the same time, in order to ensure that the battery management system of the energy storage system performs fault recording and the power conversion system (PCS) executes zero power after a short circuit occurs in the energy storage system, the relay needs to break after a preset third time. The third time can be 6 s.

[0036] In some embodiments, the first switch K1 includes a second fuse, and a third breaking current of the second fuse is greater than or equal to the second current; wherein the first fuse FU1 and the second fuse are connected in series between the first interface and the third interface, or the first fuse FU1 and the second fuse are connected in series between the second interface and the fourth interface.

[0037] In the embodiment, the first switch K1 can be a second fuse, the second fuse can be an intelligent fuse, and the third breaking current can be the maximum breaking current of the second fuse. As shown in FIG. 3, the maximum breaking current of the second fuse can be greater than or equal to the minimum breaking current of the first fuse FU1, so that the second fuse can be used for breaking when the fault current of the power supply branch is less than the second current, and the second fuse or the first fuse FU1 can be used for breaking when the fault current of the power supply branch is greater than or equal to the second current, thereby avoiding the protection blind area when the protection device in the high-voltage box 20 is used to protect the energy storage system.

[0038] In some embodiments, when the fault current of the power supply branch is greater than or equal to the first current and less than a preset third current, the breaking speed of the second fuse is greater than the breaking speed of the first fuse FU1; wherein the third current is greater than or equal to the second current; when the fault current of the power supply branch is greater than the third current, the breaking speed of the second fuse is less than the breaking speed of the first fuse FU1.

[0039] In the embodiment, in order to avoid the replacement frequency of the first fuse FU1 and at the same time avoid that the fault current of the power supply branch is too large and cannot be cut off in time, the application can set a third current, and the third current is greater than or equal to the second current.

[0040] Specifically, the third current can be 5kA, when the fault current of the power supply branch is greater than or equal to the first current and less than the third current, the breaking speed of the second fuse is greater than the breaking speed of the first fuse FU1, at this time the second fuse can be used for breaking; when the fault current of the power supply branch is equal to the third current, the second fuse or the first fuse FU1 can be used for breaking; when the fault current of the power supply branch is greater than the third current, the breaking speed of the second fuse is less than the breaking speed of the first fuse FU1, at this time the first fuse FU1 can be used for breaking.

[0041] In some embodiments, the first breaking current of the first fuse FU1 is greater than or equal to the first current; wherein when the fault current of the power supply branch is equal to the minimum breaking current of the first fuse FU1, the first fuse FU1 breaks after a preset fourth time.

[0042] Specifically, the selection of the minimum breaking current of the first fuse FU1 needs to meet the delay strategy of the battery management system in the energy storage system, and the fourth time can be 6s. For example, if the battery management system sends a command to the relay to break after a delay of 6s, at this time the first fuse FU1 cannot appear arc / spray.

[0043] In some embodiments, as shown in FIG. 2, the high-voltage box 20 further comprises: a second switch QF1, the second switch QF1 is provided with a first end, a second end, a third end and a fourth end; wherein the first end is electrically connected to the first interface, the first fuse FU1 and the first switch K1 are connected in series between the second interface and the second end, the third end is electrically connected to the third interface, and the fourth end is electrically connected to the fourth interface, or the first fuse FU1 and the first switch K1 are connected in series between the first interface and the first end, the second end is electrically connected to the second interface, the third end is electrically connected to the third interface, and the fourth end is electrically connected to the fourth interface.

[0044] In this embodiment, the second switch QF1 can be a disconnecting switch or a circuit breaker. By providing a disconnecting switch in the high-voltage box 20, the power supply branch can be disconnected when it is necessary to replace the components in the battery pack 10 and the high-voltage box 20, thereby avoiding accidents during replacement.

[0045] In some embodiments, the second switch QF1 comprises: a circuit breaker, the circuit breaker comprises: a first end, a second end, a third end and a fourth end, and the fourth breaking current of the circuit breaker is greater than or equal to the second current.

[0046] In this embodiment, the second switch QF1 can be a circuit breaker, the fourth breaking current can be the maximum breaking current of the circuit breaker, and the circuit breaker can be a split excitation circuit breaker. The breaking capacity of the circuit breaker needs to be greater than the maximum load cutting capacity of the relay, and the breaking capacity of the circuit breaker is greater than the minimum breaking capacity of the first fuse FU1, thereby avoiding the protection blind area when the high-voltage box 20 is used to protect the energy storage system.

[0047] Specifically, as shown in FIG. 3, the maximum breaking current of the circuit breaker can be greater than or equal to the minimum breaking current of the first fuse FU1, so that the circuit breaker can be used for disconnection when the fault current of the power supply branch is less than the second current, and the circuit breaker or the first fuse FU1 can be used for disconnection when the fault current of the power supply branch is greater than or equal to the second current, thereby avoiding the protection blind area when the protection device in the high-voltage box 20 is used to protect the energy storage system.

[0048] In some embodiments, when the fault current of the power supply branch is greater than or equal to the first current and less than a preset fourth current, the breaking speed of the circuit breaker is greater than the breaking speed of the first fuse FU1; wherein the fourth current is greater than or equal to the second current; when the fault current of the power supply branch is greater than the fourth current, the breaking speed of the circuit breaker is less than the breaking speed of the first fuse FU1.

[0049] In this embodiment, in order to avoid the replacement frequency of the first fuse FU1 and to avoid that the fault current of the power supply branch is too large and cannot be cut off in time, the application can set a fourth current, and the fourth current is greater than or equal to the second current.

[0050] Specifically, the fourth current can be 5kA, when the fault current of the power supply branch is greater than or equal to the first current and less than the fourth current, the breaking speed of the circuit breaker is greater than the breaking speed of the first fuse FU1, at this time, the circuit breaker can be used for breaking; when the fault current of the power supply branch is equal to the fourth current, the circuit breaker or the first fuse FU1 can be used for breaking; when the fault current of the power supply branch is greater than the fourth current, the breaking speed of the circuit breaker is less than the breaking speed of the first fuse FU1, at this time, the first fuse FU1 can be used for breaking.

[0051] In some embodiments, as shown in FIG. 2, the energy storage system includes: a third switch QS1 and N power supply branches, N is a positive integer and greater than or equal to 2; wherein, after the N power supply branches are connected in parallel, the target device is electrically connected through the third switch QS1.

[0052] In this embodiment, the third switch QS1 can be a disconnecting switch, and the target device can be an energy storage converter, and the PCS+ interface and the PCS- interface of the third switch QS1 are electrically connected with the energy storage converter. By setting the disconnecting switch between the energy storage converter and the high-voltage box 20, the main circuit of the energy storage system can be disconnected by using the third switch QS1 when the high-voltage box 20 cannot be broken, so as to further ensure the safety performance of the energy storage system.

[0053] In some embodiments, N times of the fifth breaking current of the third switch QS1 is the preset fifth current, and the fifth current is greater than the minimum breaking current of the first fuse FU1.

[0054] Specifically, the application can also solve the problem of protection blind area of the high-voltage box 20 by using the third switch QS1, and the fifth breaking current can be the maximum breaking current of the third switch QS1, so that when the fault current of the power supply branch is less than or equal to the minimum breaking current of the first fuse FU1, the third switch QS1 can be used for breaking; when the fault current of the power supply branch is greater than the minimum breaking current of the first fuse FU1, the first fuse FU1 can be used for breaking, so as to avoid the protection blind area when the protection device in the high-voltage box 20 is used to protect the energy storage system.

[0055] In the embodiment, the breaking capacity of the third switch QS1 needs to be decomposed to the power supply branch layer. If there are N power supply branches in the energy storage system, the fifth current, which is the maximum breaking current of the third switch QS1 divided by N, needs to be greater than the minimum breaking current of the first fuse FU1. Thus, when the fault current of the power supply branch is less than or equal to the minimum breaking current of the first fuse FU1, the third switch QS1 can be used for breaking; when the fault current of the power supply branch is greater than the minimum breaking current of the first fuse FU1, the first fuse FU1 can be used for breaking, thereby avoiding the protection blind area when the protection device in the high-voltage box 20 is used to protect the energy storage system.

[0056] When the fault current of the power supply branch is greater than or equal to the first current and less than a preset sixth current, the breaking speed of the third switch QS1 is greater than the breaking speed of the first fuse FU1; wherein the sixth current is greater than or equal to the second current; when the fault current of the power supply branch is greater than the sixth current, the breaking speed of the third switch QS1 is less than the breaking speed of the first fuse FU1.

[0057] In the embodiment, in order to avoid the replacement frequency of the first fuse FU1 and to avoid that the fault current of the power supply branch is too large and cannot be cut off in time, the application can set a sixth current, which is greater than or equal to the second current.

[0058] Specifically, the sixth current can be 5kA. When the fault current of the power supply branch is greater than or equal to the first current and less than the sixth current, the breaking speed of the third switch QS1 is greater than the breaking speed of the first fuse FU1, and the third switch QS1 can be used for breaking at this time; when the fault current of the power supply branch is equal to the sixth current, the third switch QS1 or the first fuse FU1 can be used for breaking; when the fault current of the power supply branch is greater than the sixth current, the breaking speed of the third switch QS1 is less than the breaking speed of the first fuse FU1, and the first fuse FU1 can be used for breaking at this time.

[0059] In some embodiments, as shown in FIG. 2, the battery pack 10 includes: a third fuse FU2 and at least one battery cell, the sixth breaking current of the third fuse FU2 is greater than or equal to the first breaking current of the first fuse FU1; wherein the third fuse FU2 and the at least one battery cell are connected in series and are respectively connected to one end of the battery pack 10 and the other end of the battery pack 10; or, the third fuse FU2 and the battery cell are connected in series one by one and are respectively connected to one end of the battery pack 10 and the other end of the battery pack 10 to realize parallel connection.

[0060] In the embodiment, the first breaking current can be the minimum breaking current of the first fuse FU1, and the sixth breaking current can be the minimum breaking current of the third fuse FU2. By arranging the third fuse FU2 in the battery pack 10, when a short circuit occurs in the battery pack 10, the third fuse FU2 can timely cut off the loop in which the battery pack 10 is located, so as to ensure the safety of the battery pack 10. Meanwhile, the minimum breaking current of the third fuse FU2 can be greater than or equal to the minimum breaking current of the first fuse FU1, so that the third fuse FU2 can be prevented from being fused earlier than the first fuse FU1, thereby reducing the replacement frequency of the third fuse FU2 when replacing the fuse of the power supply branch, and the disassembly and assembly frequency of the battery pack 10 can be reduced, the maintenance efficiency of the energy storage system is greatly improved, and the maintenance cost of the energy storage system is reduced.

[0061] In some embodiments, the fusing speed of the first fuse FU1 is greater than the fusing speed of the third fuse FU2.

[0062] In the embodiment, the fusing speed of the first fuse FU1 is greater than the fusing speed of the third fuse FU2, so that the first fuse can be preferentially fused when the first fuse FU1 and the third fuse FU2 both reach the breaking condition, thereby avoiding increasing the disassembly and assembly frequency of the battery pack 10.

[0063] In some embodiments, the target device is an energy storage converter; and when the current of the power supply branch is greater than or equal to the first current and less than or equal to the second current, the energy storage converter controls the battery pack 10 in the power supply branch to stop charging or / and stop discharging.

[0064] The energy storage converter can control the charging and discharging process of the power supply branch, and convert AC and DC, and can also directly supply power to an AC load in the absence of a power grid.

[0065] In some embodiments, as shown in FIG. 4, the application also provides a protection method of an energy storage system. The execution subject of the protection method is a power consumption device or a control module in the power consumption device. The control module can be a battery management system (BMS), a vehicle control unit (VCU), etc.

[0066] The embodiments of the application are described in detail below with the execution subject being a battery management system (BMS) as an example.

[0067] As shown in FIG. 4, a protection method of an energy storage system includes steps S110 and S120.

[0068] S110, when it is detected that the fault current of the power supply branch is greater than or equal to a preset first current and less than a preset second current, a first switch K1 is sent a cut-off instruction to cut off the power supply branch;

[0069] S120, when it is detected that the fault current of the power supply branch is greater than or equal to the preset second current, a first fuse FU1 is fused to cut off the power supply branch.

[0070] In the embodiment, the breaking current of the first switch K1 is greater than or equal to the first current, the first breaking current of the first fuse FU1 is less than or equal to the second current, the first breaking current can be the minimum breaking current of the first fuse FU1, the first current is less than or equal to the second current, and the interval between the first current and the second current can be understood as a protection blind area of the energy storage system. Thus, when it is detected that the fault current of the power supply branch is greater than or equal to the first current and less than the second current, the battery management system can send a cut-off instruction to the first switch K1 to cut off the power supply branch; when it is detected that the fault current of the power supply branch is greater than or equal to the second current, the first fuse FU1 is fused to cut off the power supply branch. Therefore, when the high-voltage box 20 is used to protect the energy storage system, the protection blind area can be avoided, the global protection of the energy storage system is realized, and the safety performance of the energy storage system is greatly improved.

[0071] In addition, the breaking speed of the first switch K1 is greater than the breaking speed of the first fuse FU1. Thus, when the first switch K1 and the first fuse FU1 both meet the breaking condition, the first switch K1 is preferentially used for breaking, so that the number of replacements of the first fuse FU1 is reduced, and the maintenance cost of the energy storage system is reduced.

[0072] In some embodiments, the first switch K1 includes a relay. When it is detected that the fault current of the power supply branch is greater than or equal to the preset first current and less than the preset second current, a cut-off instruction is sent to the first switch K1 to cut off the power supply branch, including the following steps: when it is detected that the fault current of the power supply branch is greater than or equal to the first current and less than the second current, a cut-off instruction is sent to the relay after a preset first delay time to cut off the power supply branch.

[0073] Specifically, the first fuse FU1 and the relay are connected in series between the first interface and the third interface, or the first fuse FU1 and the relay are connected in series between the second interface and the fourth interface. The second breaking current of the relay is greater than or equal to the first current and less than or equal to the second current, and the breaking speed of the relay is greater than the breaking speed of the first fuse FU1.

[0074] In the embodiment, the first switch K1 can be a relay, the second breaking current can be the maximum breaking current of the relay, and the relay and the first fuse FU1 in series can be arranged in the high-voltage box 20 to protect the energy storage system. To avoid a protection blind area, the maximum breaking current of the relay needs to be greater than or equal to the first current (e.g., 1 kA) and less than or equal to the second current (e.g., 4 kA). Thus, when the fault current of the power supply branch of the energy storage system is less than or equal to the second current, the relay can be used for protection, and when the fault current is greater than the second current, the first fuse FU1 can be used for protection, thereby avoiding the protection blind area.

[0075] In addition, the application can also be provided with two groups of relays and first fuses FU1 in series in the high-voltage box 20. One group of relays and first fuses FU1 are connected in series between the first interface and the third interface, and the other group of relays and first fuses FU1 are connected in series between the second interface and the fourth interface.

[0076] In some embodiments, the second breaking current of the relay is less than or equal to the first breaking current of the first fuse FU1.

[0077] Specifically, the first breaking current can be the minimum breaking current of the first fuse FU1, and the second breaking current can be the maximum breaking current of the relay. Generally, during normal operation of the relay, if the fault current in the power supply branch is too large, the relay is prone to sticking. To reduce the probability of sticking of the relay, when the fault current of the power supply branch is between the first current and the second current, the second breaking current of the relay can be less than or equal to the minimum breaking current of the first fuse FU1, so that the relay can be used for breaking between the first current and the minimum breaking current of the first fuse FU1, and the first fuse FU1 can be used for breaking between the minimum breaking current of the first fuse FU1 and the second current.

[0078] In some embodiments, when the fault current of the power supply branch is equal to the second breaking current of the relay, the direct-current time constant of the energy storage system is greater than or equal to a preset first time and less than or equal to a preset second time, and the relay breaks after a preset third time (i.e., a first delay time).

[0079] Specifically, to ensure that the relay can break at the maximum breaking current when the fault current of the power supply branch is equal to the second breaking current of the relay, the energy storage system provided by the application also needs to meet certain conditions, i.e., the direct-current time constant of the energy storage system needs to be greater than or equal to a preset first time and less than or equal to a preset second time. The first time can be 1 ms, and the second time can be 3 ms.

[0080] Meanwhile, in order to ensure that the battery management system of the energy storage system performs fault recording and the power conversion system (PCS) performs zero power after a short circuit of the energy storage system occurs, the relay needs to be disconnected after a preset third time. The third time can be 6s.

[0081] In some embodiments, the first switch K1 includes a second fuse, and the protection method of the energy storage system further includes the following steps: when it is detected that the fault current of the power supply branch is greater than or equal to the first current and less than a preset third current, sending a cutting instruction to the second fuse to cut off the power supply branch; wherein the third current is greater than the second current.

[0082] Specifically, the second fuse can be an intelligent fuse, the third breaking current of the second fuse is greater than or equal to the second current, the first fuse FU1 and the second fuse are connected in series between the first interface and the third interface, or the first fuse FU1 and the second fuse are connected in series between the second interface and the fourth interface.

[0083] As shown in FIG. 3, the third breaking current can be the maximum breaking current of the second fuse, that is, the maximum breaking current of the second fuse can be greater than or equal to the minimum breaking current of the first fuse FU1, so that the second fuse can be used for disconnection when the fault current of the power supply branch is less than the second current, and the second fuse or the first fuse FU1 can be used for disconnection when the fault current of the power supply branch is greater than or equal to the second current, so that a protection blind area can be avoided when the protection device in the high-voltage box 20 is used to protect the energy storage system.

[0084] In some embodiments, the protection method of the energy storage system further includes the following steps: when it is detected that the fault current of the power supply branch is greater than or equal to the third current, the first fuse FU1 is fused to cut off the power supply branch.

[0085] In this embodiment, in order to avoid the replacement frequency of the first fuse FU1 and avoid that the fault current of the power supply branch is too large and the power supply branch cannot be cut off in time, a third current greater than or equal to the second current can be set.

[0086] Specifically, when the fault current of the power supply branch is greater than or equal to the first current and less than the third current, the breaking speed of the second fuse is greater than the breaking speed of the first fuse FU1; wherein the third current is greater than or equal to the second current; when the fault current of the power supply branch is greater than the third current, the breaking speed of the second fuse is less than the breaking speed of the first fuse FU1.

[0087] For example, the third current can be 5 kA, when the fault current of the power supply branch is greater than or equal to the first current and less than the third current, the breaking speed of the second fuse is greater than the breaking speed of the first fuse FU1, at this time the second fuse can be used for breaking; when the fault current of the power supply branch is equal to the third current, the second fuse or the first fuse FU1 can be used for breaking; when the fault current of the power supply branch is greater than the third current, the breaking speed of the second fuse is less than the breaking speed of the first fuse FU1, at this time the first fuse FU1 can be used for breaking.

[0088] In some embodiments, the first breaking current of the first fuse FU1 is greater than or equal to the first current; wherein when the fault current of the power supply branch is equal to the minimum breaking current of the first fuse FU1, the first fuse FU1 breaks after a preset fourth time.

[0089] Specifically, the first breaking current can be the minimum breaking current of the first fuse FU1, and the selection of the minimum breaking current of the first fuse FU1 needs to meet the delay strategy of the battery management system in the energy storage system, and the fourth time can be 6s. For example, if the battery management system sends a command to the relay to break after a delay of 6s, the first fuse FU1 cannot have arc or explosion.

[0090] In some embodiments, as shown in FIG. 2, the high-voltage box 20 further comprises a second switch QF1, and the protection method of the energy storage system further comprises the following steps: when it is detected that the fault current of the power supply branch is greater than or equal to the first current and less than a preset fourth current, sending a cut-off instruction to the second switch QF1 to cut off the power supply branch; wherein the fourth current is greater than the second current.

[0091] In the embodiment, the high-voltage box 20 further comprises a second switch QF1, and the second switch QF1 is provided with a first end, a second end, a third end and a fourth end; wherein the first end is electrically connected to the first interface, the first fuse FU1 and the first switch K1 are connected in series between the second interface and the second end, the third end is electrically connected to the third interface, and the fourth end is electrically connected to the fourth interface, or the first fuse FU1 and the first switch K1 are connected in series between the first interface and the first end, the second end is electrically connected to the second interface, the third end is electrically connected to the third interface, and the fourth end is electrically connected to the fourth interface.

[0092] The second switch QF1 can be a disconnecting switch or a circuit breaker. By providing a disconnecting switch in the high-voltage box 20, the power supply branch can be broken when it is necessary to replace the battery pack 10 and the components in the high-voltage box 20, thereby avoiding accidents during the replacement process.

[0093] In some embodiments, the second switch QF1 can be a circuit breaker, and the protection method of the energy storage system further comprises the following steps: when it is detected that the fault current of the power supply branch is greater than or equal to the fourth current, the first fuse FU1 is blown to cut off the power supply branch.

[0094] In the embodiment, the fourth breaking current of the circuit breaker is greater than or equal to the second current, the fourth breaking current can be the maximum breaking current of the circuit breaker, and the circuit breaker can be a split-break circuit breaker, the breaking capacity of the circuit breaker needs to be greater than the maximum load breaking capacity of the relay, and at the same time, the breaking capacity of the circuit breaker is greater than the minimum breaking capacity of the first fuse FU1, thereby avoiding the protection blind area when the protection device in the high-voltage box 20 is used to protect the energy storage system.

[0095] As shown in FIG. 3, the maximum breaking current of the circuit breaker can be greater than or equal to the minimum breaking current of the first fuse FU1, so that the circuit breaker can be used for breaking when the fault current of the power supply branch is less than the second current, and the circuit breaker or the first fuse FU1 can be used for breaking when the fault current of the power supply branch is greater than or equal to the second current, thereby avoiding the protection blind area when the protection device in the high-voltage box 20 is used to protect the energy storage system. The timing of sending the cut-off instruction to the circuit breaker can be after detecting the fault current 1s.

[0096] In some embodiments, in order to avoid the replacement frequency of the first fuse FU1 and at the same time avoid that the fault current of the power supply branch is too large and the power supply branch cannot be cut off in time, the present application can set a fourth current greater than or equal to the second current.

[0097] Specifically, when the fault current of the power supply branch is greater than or equal to the first current and less than the fourth current, the breaking speed of the circuit breaker is greater than the breaking speed of the first fuse FU1; wherein the fourth current is greater than or equal to the second current; when the fault current of the power supply branch is greater than the fourth current, the breaking speed of the circuit breaker is less than the breaking speed of the first fuse FU1.

[0098] For example, the fourth current can be 5kA, when the fault current of the power supply branch is greater than or equal to the first current and less than the fourth current, the breaking speed of the circuit breaker is greater than the breaking speed of the first fuse FU1, at this time the circuit breaker can be used for breaking; when the fault current of the power supply branch is equal to the fourth current, the circuit breaker or the first fuse FU1 can be used for breaking; when the fault current of the power supply branch is greater than the fourth current, the breaking speed of the circuit breaker is less than the breaking speed of the first fuse FU1, at this time the first fuse FU1 can be used for breaking.

[0099] In some embodiments, the energy storage system comprises a third switch QS1 and a plurality of power supply branches, the plurality of power supply branches are connected in parallel and electrically connected with the third switch QS1, and the protection method of the energy storage system further comprises the following steps: when the fault current of the power supply branch is greater than or equal to the first current and less than a preset fifth current, a cut-off instruction is sent to the third switch QS1 to cut off the power supply branch; wherein the fifth current is greater than or equal to the second current; when the fault current of the power supply branch is greater than or equal to the fifth current, the first fuse FU1 is fused to cut off the power supply branch.

[0100] In the embodiment, the third switch QS1 can be a disconnecting switch, and the target device can be an energy storage converter, and the PCS+ interface and the PCS- interface of the third switch QS1 are electrically connected with the energy storage converter. By arranging the disconnecting switch between the energy storage converter and the high-voltage box 20, the main circuit of the energy storage system can be disconnected by the third switch QS1 when the high-voltage box 20 cannot be broken, so that the safety performance of the energy storage system can be further ensured.

[0101] Specifically, the fifth current can be obtained by dividing the maximum breaking current of the third switch QS1 by the number of the power supply branches, and the fifth current is greater than the minimum breaking current of the first fuse FU1, so that the problem of the protection blind area of the high-voltage box 20 can be solved by the third switch QS1. When the fault current of the power supply branch is less than or equal to the minimum breaking current of the first fuse FU1, the third switch QS1 can be used for breaking; when the fault current of the power supply branch is greater than the minimum breaking current of the first fuse FU1, the first fuse FU1 can be used for breaking, so that the protection blind area can be avoided when the protection device in the high-voltage box 20 is used to protect the energy storage system.

[0102] In order to avoid the replacement frequency of the first fuse FU1 and avoid that the fault current of the power supply branch is too large and the power supply branch cannot be cut off in time, a sixth current can be set, and the sixth current is greater than or equal to the second current.

[0103] Specifically, when the fault current of the power supply branch is greater than or equal to the first current and less than a preset sixth current, the breaking speed of the third switch QS1 is greater than the breaking speed of the first fuse FU1; wherein the sixth current is greater than or equal to the second current; when the fault current of the power supply branch is greater than the sixth current, the breaking speed of the third switch QS1 is less than the breaking speed of the first fuse FU1.

[0104] For example, the sixth current can be 5kA, when the fault current of the power supply branch is greater than or equal to the first current and less than the sixth current, the breaking speed of the third switch QS1 is greater than the breaking speed of the first fuse FU1, at this time, the third switch QS1 can be used for breaking; when the fault current of the power supply branch is equal to the sixth current, the third switch QS1 or the first fuse FU1 can be used for breaking; when the fault current of the power supply branch is greater than the sixth current, the breaking speed of the third switch QS1 is less than the breaking speed of the first fuse FU1, at this time, the first fuse FU1 can be used for breaking.

[0105] In some embodiments, the protection method of the energy storage system further comprises the following steps: determining the fifth current according to the number of power supply branches and the breaking current of the third switch QS1; wherein the fifth current is greater than the first breaking current of the first fuse FU1.

[0106] In the embodiment, the breaking capacity of the third switch QS1 needs to be decomposed to the power supply branch layer, and then the fifth current can be determined according to the number of power supply branches and the fifth breaking current of the third switch QS1. The fifth breaking current can be the maximum breaking current of the third switch QS1, and the first breaking current can be the minimum breaking current of the first fuse FU1.

[0107] For example, there are N power supply branches in the energy storage system, and then the current after the maximum breaking current of the third switch QS1 is divided by N, that is, the fifth current, needs to be greater than the minimum breaking current of the first fuse FU1, so that when the fault current of the power supply branch is less than or equal to the minimum breaking current of the first fuse FU1, the third switch QS1 can be used for breaking; when the fault current of the power supply branch is greater than the minimum breaking current of the first fuse FU1, the first fuse FU1 can be used for breaking, thereby avoiding the protection blind area when the protection device in the high-voltage box 20 is used to protect the energy storage system.

[0108] In some embodiments, as shown in FIG. 2, the battery pack 10 comprises: a third fuse FU2 and at least one battery cell, the sixth breaking current of the third fuse FU2 is greater than or equal to the first breaking current of the first fuse FU1; wherein the third fuse FU2 and the at least one battery cell are connected in series and respectively connected to one end of the battery pack 10 and the other end of the battery pack 10; or, the third fuse FU2 and the battery cell are connected in series one by one and respectively connected to one end of the battery pack 10 and the other end of the battery pack 10 to realize parallel connection.

[0109] In the embodiment, the first breaking current can be the minimum breaking current of the first fuse FU1, and the sixth breaking current can be the minimum breaking current of the third fuse FU2. By arranging the third fuse FU2 in the battery pack 10, when a short circuit occurs in the battery pack 10, the third fuse FU2 can timely cut off the loop in which the battery pack 10 is located, thereby ensuring the safety of the battery pack 10.

[0110] Meanwhile, the minimum breaking current of the third fuse FU2 can be greater than or equal to the minimum breaking current of the first fuse FU1, thereby avoiding the third fuse FU2 from being blown earlier than the first fuse FU1, so that the replacement frequency of the third fuse FU2 can be reduced when the fuses in the subsequent power supply branch are replaced, thereby reducing the disassembly frequency of the battery pack 10, greatly improving the maintenance efficiency of the energy storage system, and reducing the maintenance cost of the energy storage system.

[0111] In some embodiments, the blowing speed of the first fuse FU1 is greater than the blowing speed of the third fuse FU2.

[0112] In the embodiment, the blowing speed of the first fuse FU1 is greater than the blowing speed of the third fuse FU2, so that the first fuse can be blown preferentially when the first fuse FU1 and the third fuse FU2 both reach the breaking condition, thereby avoiding increasing the disassembly frequency of the battery pack 10.

[0113] In some embodiments, after step S120, the following step is further included: if it is detected that the preset current exists in the power supply branch and the preset current is greater than the preset threshold current, the third fuse FU2 is blown to cut off the power supply branch.

[0114] In the embodiment, the preset current is the current detected in the power supply branch in which the first fuse FU1 is located after the first fuse FU1 is blown. After the first fuse FU1 is blown, the power supply branch in which the first fuse FU1 is located is usually 0, but there can be a case that the first fuse FU1 is not completely blown, so that the loop of the power supply branch is not cut off. Therefore, it is necessary to detect whether the preset current exists in the power supply branch and whether the preset current is greater than the preset threshold current. If the preset current is greater than the preset threshold current, it can be determined that the loop of the power supply branch is not cut off, and therefore the third fuse FU2 in the power supply branch needs to be blown to cut off the loop of the power supply branch.

[0115] In some embodiments, the target device is an energy storage converter; and when the current of the power supply branch is greater than or equal to the first current and less than or equal to the second current, the energy storage converter controls the battery pack 10 in the power supply branch to stop charging or / and stop discharging.

[0116] In some embodiments, step S110 comprises the following steps: sending a power control instruction to the energy storage converter, and after a first preset time, acquiring the power of the energy storage converter; if the power of the energy storage converter is greater than a preset power, sending a shutoff instruction to the first switch K1 to shut off the power supply branch.

[0117] In the embodiment, the energy storage converter can control the charging and discharging process of the power supply branch, and perform AC-DC conversion, and can also directly supply power to the AC load in the case of no power grid. The first preset time can be the time when the battery management system performs fault recording when the fault current of the power supply branch is between the first current and the second current, for example, the first preset time can be 3s.

[0118] In some embodiments, before sending the power control instruction to the energy storage converter, the following step is further included: if it is detected that the power supply branch has a fault current, performing fault recording on the battery management system of the energy storage system.

[0119] In the embodiment, the fault recording is a dispatch end power grid fault diagnosis system based on fault recording information. The fault recorder is applied to the energy storage system, and can automatically and accurately record the change of various electrical quantities before and after the fault when the energy storage system fails. Through analysis, comparison and analysis of the electrical quantities, it is important to improve the safety operation level of the energy storage system.

[0120] In some embodiments, as shown in FIG. 5, the second switch QF1 is a disconnector, and the protection method of the energy storage system comprises the following steps: when it is detected that the fault current of the power supply branch is greater than or equal to 400A and less than or equal to 5000A, the battery management system performs fault recording; after 3s, the battery management system sends an instruction to the energy storage converter to make the energy storage converter operate at zero power; after 1s, if the energy storage converter does not operate at zero power, the battery management system sends an instruction to the third switch QS1 to make the third switch QS1 open; after 1s, if the third switch QS1 is not opened, the battery management system sends an instruction to the first switch K1 to make the first switch K1 open, thereby ensuring that the energy storage system is in standby state; when it is detected that the fault current of the power supply branch is greater than 5000A, the first fuse FU1 is blown; if it is detected that the first fuse FU1 is not blown, the third fuse FU2 is blown, thereby ensuring that the energy storage system is in standby state.

[0121] In some embodiments, as shown in FIG. 6, the second switch QF1 is a disconnector, and the protection method of the energy storage system includes the following steps: when it is detected that the fault current of the power supply branch is greater than or equal to 400 A and less than or equal to 5000 A, the battery management system performs fault recording; after 3 s, the battery management system sends an instruction to the energy storage converter, so that the energy storage converter operates at zero power; after 1 s, if the energy storage converter does not operate at zero power, the battery management system sends an instruction to the third switch QS1, so that the third switch QS1 is disconnected; after 1 s, if the third switch QS1 is not disconnected, the battery management system sends an instruction to the second switch QF1, so that the second switch QF1 is disconnected; after 1 s, if the second switch QF1 is not disconnected, the battery management system sends an instruction to the first switch K1, so that the first switch K1 is disconnected, thereby ensuring that the energy storage system is in a standby state; when it is detected that the fault current of the power supply branch is greater than 5000 A, the first fuse FU1 is blown; if it is detected that the first fuse FU1 is not blown, the third fuse FU2 is blown, thereby ensuring that the energy storage system is in a standby state.

[0122] The energy storage system and the protection method of the energy storage system provided by the present application, the energy storage system includes: at least one power supply branch, the power supply branch includes: at least one battery pack 10 and a high-voltage box 20, the high-voltage box 20 includes: a first switch K1 and a first fuse FU1, thereby when it is detected that the fault current of the power supply branch is greater than or equal to a preset first current and less than a preset second current, a cut-off instruction is sent to the first switch K1 to cut off the power supply branch; when it is detected that the fault current of the power supply branch is greater than or equal to the preset second current, the first fuse FU1 is blown to cut off the power supply branch, thereby when the high-voltage box 20 is used to protect the energy storage system, a protection blind area can be avoided, the energy storage system is protected in the whole domain, and the safety performance of the energy storage system is greatly improved.

Claims

1. An energy storage system, comprising: At least one power supply branch, said power supply branch comprising: At least one battery pack (10); The high-voltage box (20) includes: a first fuse (FU1) and a first switch (K1); the first fuse (FU1) and the first switch (K1) are connected in series between the first interface and the third interface of the high-voltage box (20), or the first fuse (FU1) and the first switch (K1) are connected in series between the second interface and the fourth interface of the high-voltage box (20); the first interface is electrically connected to one end of the battery pack (10), the second interface is electrically connected to the other end of the battery pack (10), and the third interface and the fourth interface are respectively electrically connected to the target device; Wherein, the breaking current of the first switch (K1) is greater than or equal to a preset first current, the first breaking current of the first fuse (FU1) is less than or equal to a preset second current, the first current is less than or equal to the second current, and the breaking speed of the first switch (K1) is greater than the breaking speed of the first fuse (FU1).

2. The energy storage system according to claim 1, wherein, The first switch (K1) includes: a relay, a first fuse (FU1), the relay being connected in series between the first interface and the third interface, or the first fuse (FU1) and the relay being connected in series between the second interface and the fourth interface; Wherein, the second breaking current of the relay is greater than or equal to the first current and less than or equal to the second current, and the breaking speed of the relay is greater than the breaking speed of the first fuse (FU1).

3. The energy storage system according to claim 2, wherein, The second breaking current of the relay is less than or equal to the first breaking current of the first fuse (FU1).

4. The energy storage system according to claim 2, wherein, When the fault current of the power supply branch is equal to the second breaking current of the relay, the DC time constant of the energy storage system is greater than or equal to the preset first time and less than or equal to the preset second time, and the relay breaks after the preset third time.

5. The energy storage system according to claim 1, wherein, The first switch (K1) includes: a second fuse (FU2), wherein the third breaking current of the second fuse (FU2) is greater than or equal to the second current; The first fuse (FU1) and the second fuse (FU2) are connected in series between the first interface and the third interface, or the first fuse (FU1) and the second fuse (FU2) are connected in series between the second interface and the fourth interface.

6. The energy storage system according to claim 5, wherein, When the fault current of the power supply branch is greater than or equal to the first current and less than the preset third current, the breaking speed of the second fuse (FU2) is greater than the breaking speed of the first fuse (FU1); wherein the third current is greater than or equal to the second current. When the fault current of the power supply branch is greater than the third current, the breaking speed of the second fuse (FU2) is less than the breaking speed of the first fuse (FU1).

7. The energy storage system according to any one of claims 1-6, wherein, When the fault current of the power supply branch is equal to the first breaking current of the first fuse (FU1), the first fuse (FU1) will break after a preset fourth time.

8. The energy storage system according to any one of claims 1-6, wherein, The high-voltage box (20) further includes: a second switch (QF1), which is provided with a first terminal, a second terminal, a third terminal and a fourth terminal; Wherein, the first end is electrically connected to the first interface, the first fuse (FU1) and the first switch (K1) are connected in series between the second interface and the second end, the third end is electrically connected to the third interface, and the fourth end is electrically connected to the fourth interface; or, the first fuse (FU1) and the first switch (K1) are connected in series between the first interface and the first end, the second end is electrically connected to the second interface, the third end is electrically connected to the third interface, and the fourth end is electrically connected to the fourth interface.

9. The energy storage system according to claim 8, wherein, The second switch (QF1) includes a circuit breaker, which includes a first terminal, a second terminal, a third terminal, and a fourth terminal, wherein the fourth breaking current of the circuit breaker is greater than or equal to the second current.

10. The energy storage system according to claim 9, wherein, When the fault current of the power supply branch is greater than or equal to the first current and less than the preset fourth current, the breaking speed of the circuit breaker is greater than the breaking speed of the first fuse (FU1); wherein the fourth current is greater than or equal to the second current. When the fault current of the power supply branch is greater than the fourth current, the breaking speed of the circuit breaker is less than the breaking speed of the first fuse (FU1).

11. The energy storage system according to any one of claims 1-6, further comprising: The third switch (QS1) and N power supply branches, where N is a positive integer greater than or equal to 2; Among them, the N power supply branches are connected in parallel and then electrically connected to the target device through the third switch (QS1).

12. The energy storage system according to claim 11, wherein, The fifth breaking current of the third switch (QS1) is one-Nth of the preset fifth current, which is greater than the first breaking current of the first fuse (FU1).

13. The energy storage system according to any one of claims 1-6, wherein, The battery pack (10) includes: a third fuse and at least one battery cell, wherein the sixth breaking current of the third fuse is greater than or equal to the first breaking current of the first fuse (FU1); The third fuse and at least one of the battery cells are connected in series and electrically connected to one end of the battery pack (10) and the other end of the battery pack (10), respectively; or, the third fuse and the battery cells are connected in series one-to-one and electrically connected to one end of the battery pack (10) and the other end of the battery pack (10) respectively to achieve parallel connection.

14. The energy storage system according to claim 13, wherein, The fusing speed of the first fuse (FU1) is greater than that of the third fuse.

15. The energy storage system according to any one of claims 1-6, wherein, The target device is an energy storage converter; When the current of the power supply branch is greater than or equal to the first current and less than or equal to the second current, the energy storage converter controls the battery pack (10) in the power supply branch to stop charging and / or stop discharging.

16. A protection method for an energy storage system, the energy storage system comprising: At least one power supply branch, the power supply branch comprising: at least one battery pack (10) and a high-voltage box (20), the high-voltage box (20) comprising: a first switch (K1) and a first fuse (FU1), the method comprising: When the fault current of the power supply branch is detected to be greater than or equal to a preset first current and less than a preset second current, a cut-off command is sent to the first switch (K1) to cut off the power supply branch. When a fault current in the power supply branch is detected to be greater than or equal to a preset second current, the first fuse (FU1) blows to cut off the power supply branch.

17. The protection method for an energy storage system according to claim 16, wherein, The first switch (K1) includes: a relay; The step of sending a disconnection command to the first switch (K1) to disconnect the power supply branch when the detected fault current of the power supply branch is greater than or equal to a preset first current and less than a preset second current includes: When a fault current in the power supply branch is detected to be greater than or equal to the first current and less than the second current, a cut-off command is sent to the relay after a preset first delay time to cut off the power supply branch.

18. The protection method for an energy storage system according to claim 16, wherein, The first switch (K1) includes a second fuse (FU2), and the method further includes: When a fault current in the power supply branch is detected to be greater than or equal to the first current and less than a preset third current, a disconnection command is sent to the second fuse (FU2) to disconnect the power supply branch; wherein the third current is greater than the second current.

19. The protection method for an energy storage system according to claim 18, further comprising: When a fault current in the power supply branch is detected to be greater than or equal to the third current, the first fuse (FU1) blows to disconnect the power supply branch.

20. The protection method for the energy storage system according to claim 16, wherein the high-voltage box (20) further comprises: The method further includes: a second switch (QF1) and the method also includes: When a fault current in the power supply branch is detected to be greater than or equal to the first current and less than a preset fourth current, a disconnection command is sent to the second switch (QF1) to disconnect the power supply branch; wherein the fourth current is greater than the second current.

21. The protection method for an energy storage system according to claim 20, wherein the second switch (QF1) comprises: The method further includes: a circuit breaker. When a fault current in the power supply branch is detected to be greater than or equal to the fourth current, the first fuse (FU1) blows to disconnect the power supply branch.

22. The protection method for an energy storage system according to claim 16, wherein the energy storage system comprises: The method further includes: a third switch (QS1) and multiple power supply branches, wherein the multiple power supply branches are connected in parallel and electrically connected to the third switch (QS1); When the fault current of the power supply branch is greater than or equal to the first current and less than the preset fifth current, a disconnection command is sent to the third switch (QS1) to disconnect the power supply branch; wherein the fifth current is greater than or equal to the second current.

23. The protection method for an energy storage system according to claim 22 further includes: When the fault current of the power supply branch is greater than or equal to the fifth current, the first fuse (FU1) blows to cut off the power supply branch.

24. The protection method for an energy storage system according to claim 22 further includes: The fifth current is determined based on the number of power supply branches and the breaking current of the third switch (QS1); wherein the fifth current is greater than the first breaking current of the first fuse (FU1).

25. The protection method for an energy storage system according to any one of claims 16-24, wherein, The energy storage system further includes: an energy storage converter, which is electrically connected to the power supply branch; The step of sending a disconnection command to the first switch (K1) to disconnect the power supply branch includes: Send a power control command to the energy storage converter, and obtain the power of the energy storage converter after a first preset time; If the power of the energy storage converter is greater than the preset power, a cut-off command is sent to the first switch (K1) to cut off the power supply branch.

26. The protection method for an energy storage system according to claim 25, wherein, Before sending the power control command to the energy storage converter, the method further includes: If a fault current is detected in the power supply branch, the battery management system of the energy storage system will be recorded for fault.

27. The protection method for an energy storage system according to any one of claims 16-24, wherein, The third fuse of the battery pack (10); Wherein, after the first fuse (FU1) blows to disconnect the power supply branch when the fault current of the power supply branch is detected to be greater than or equal to a preset second current, the method further includes: If a preset current is detected in the power supply branch, and the preset current is greater than a preset threshold current, the third fuse is blown to cut off the power supply branch.

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