Energy storage system circuit protection method and energy storage system circuit

Abstract

The present invention provides an energy storage system loop protection method and an energy storage system loop, wherein the energy storage system loop comprises at least one power supply branch; wherein the power supply branch comprises a high-voltage box, and the high-voltage box comprises a first fuse and a first relay. The energy storage system loop protection method sends a cut-off instruction to the first relay to disconnect the power supply branch when detecting that a fault current of the power supply branch is less than or equal to a preset current threshold, and when the fault current is greater than the preset current threshold, the first fuse is blown to disconnect the power supply branch, thereby realizing disconnection protection of the energy storage system loop under a full range of fault currents, protecting the energy storage system loop to the greatest extent, facilitating maintenance of the energy storage system loop, and improving the safety of operation of the energy storage system loop.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage systems, and in particular to an energy storage system circuit protection method and an energy storage system circuit. Background Art

[0002] Energy storage systems are equipped with fuses in the high-voltage box, battery rack, and combiner cabinet. In the event of a fault in the high-voltage box or combiner cabinet, the fuses in the box will 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. Consequently, existing energy storage system circuits suffer from high maintenance difficulty, high maintenance costs, and a low system design safety factor. Summary of the Invention

[0003] The embodiments of the present invention provide an energy storage system circuit protection method and an energy storage system circuit, which can improve the technical problems of low energy storage system circuit safety performance, high maintenance difficulty, high maintenance cost and low system design safety factor in related technologies.

[0004] In a first aspect, an embodiment of the present invention provides a method for protecting an energy storage system circuit, wherein the energy storage system circuit includes at least one power supply branch; wherein the power supply branch includes a high-voltage box, and the high-voltage box includes a first fuse and a first relay. The method includes:

[0005] When it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, a cut-off instruction is sent to the first relay to disconnect the power supply branch;

[0006] When the fault current is greater than the preset current threshold, the first fuse blows to disconnect the power supply branch.

[0007] In one embodiment, the preset current threshold is a peak current of the first relay.

[0008] In one embodiment, the energy storage system loop includes an energy storage converter, the power supply branch is electrically connected to the energy storage converter, and the method further includes:

[0009] When it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, a charge and discharge prohibition instruction is sent to the energy storage converter. If it is detected that the power of the energy storage converter is less than or equal to a first preset value and the current of the energy storage system loop is less than or equal to a second preset value, it is determined that the power supply branch is disconnected.

[0010] In one embodiment, a load switch is provided between the energy storage converter and the power supply branch, and the method further includes:

[0011] If it is detected that the power of the energy storage converter is greater than the first preset value and the current of the energy storage system loop is greater than the second preset value within the first preset time, the load switch is controlled to disconnect to disconnect the power supply branch.

[0012] In one embodiment, the method of controlling the load switch to be disconnected includes:

[0013] After a predetermined delay, a tripping instruction is sent to the load switch.

[0014] In one embodiment, the method further comprises:

[0015] If it is detected that the load switch does not respond to the tripping instruction within the second preset time, a cut-off instruction is sent to the first relay to disconnect the power supply branch.

[0016] In one embodiment, the power supply branch includes a first power supply branch and a second power supply branch connected in parallel, and the method further includes:

[0017] If it is detected that the fault current of the first power supply branch is less than or equal to a preset current threshold, a disconnection instruction is sent to a first relay in a high-voltage box of the first power supply branch to disconnect the corresponding first power supply branch; and / or,

[0018] If the fault current of the second power supply branch is greater than a preset current threshold, the first fuse in the high-voltage box of the second power supply branch is blown to disconnect the corresponding second power supply branch.

[0019] In one embodiment, the energy storage system loop includes a plurality of power supply branches connected in parallel, and the method further includes:

[0020] If the fault current of at least one power supply branch is greater than the preset current threshold, the first fuse in the high-voltage box of the corresponding power supply branch is blown to disconnect the corresponding power supply branch;

[0021] A disconnection instruction is sent to the first relays in other power supply branches to disconnect all power supply branches.

[0022] In one embodiment, the energy storage system loop includes at least one battery pack, and the battery pack includes an input end and an output end; each of the battery packs includes a second fuse and at least one battery cell, and the second fuse and at least one battery cell are connected in series and are respectively connected to the input end and the output end; or, each of the battery packs includes at least one second fuse and at least one battery cell, and the second fuse and the battery cell are connected in series one by one and are respectively electrically connected to the input end and the output end to achieve parallel connection; the high-voltage box includes a first interface, a second interface, a third interface and a fourth interface, 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 respectively electrically connected to the target device; the method further includes:

[0023] The fusing speed of the first fuse is set to be greater than the fusing speed of the second fuse.

[0024] In a second aspect, an embodiment of the present invention provides an energy storage system loop, which is protected by the energy storage system loop protection method as described in any one of the first aspects, wherein the energy storage system loop includes at least one power supply branch, wherein the power supply branch includes:

[0025] at least one battery pack including an input terminal and an output terminal;

[0026] 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, 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;

[0027] 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;

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

[0029] In one embodiment, the target device is an energy storage converter, and the energy storage system loop includes a load switch and a plurality of power supply branches;

[0030] Among them, after the multiple power supply branches are connected in parallel, they are electrically connected to the energy storage converter through the load switch.

[0031] Beneficial effects of the embodiments of the present invention:

[0032] In an embodiment of the present invention, upon detecting that the fault current of the power supply branch is less than or equal to a preset current threshold, a cut-off instruction is sent to the first relay to disconnect the power supply branch. When the fault current is greater than the preset current threshold, the first fuse is blown to disconnect the power supply branch. This achieves disconnection protection of the energy storage system circuit under a full range of fault currents, protects the energy storage system circuit to the greatest extent, facilitates maintenance of the energy storage system circuit, and improves the safety of the operation of the energy storage system circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 This is a flow chart of an embodiment of a method for protecting a circuit of an energy storage system provided in an embodiment of the present application;

[0035] Figure 2 This is a flow chart of another embodiment of the energy storage system circuit protection method provided in the embodiments of the present application;

[0036] Figure 3 This is a schematic structural diagram of an embodiment of the energy storage system circuit protection system provided in the embodiments of the present application;

[0037] Figure 4 This is a schematic diagram of the melting time of the first fuse in the high-voltage box and the second fuse in the battery pack under different currents, as well as the tolerance time of the first relay in the high-voltage box under different currents provided in the embodiment of the present application. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0039] like Figure 1 The figure shows a flow chart of an embodiment of the energy storage system circuit protection method in the embodiment of the present application. The execution subject of the embodiment of the present application is an electrical device or a control module in the electrical device, etc. The control module can be a BMS (Battery Management System), a VCU (Vehicle Control Unit), etc. The embodiment of the present application is described in detail by taking the execution subject as an example of BMS. The energy storage system circuit includes at least one power supply branch; wherein the power supply branch includes a high-voltage box, and the high-voltage box includes a first fuse and a first relay. The energy storage system circuit protection method includes:

[0040] 101. When it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, a cut-off instruction is sent to the first relay to disconnect the power supply branch.

[0041] The energy storage system loop includes at least one power supply branch, the power supply branch includes a high-voltage box, and the high-voltage box includes a first fuse and a first relay.

[0042] The preset current threshold is a pre-set critical current, such as 3200 A, used to determine whether the fault current of the power supply branch in the energy storage system loop is too high. The fault current is the current detected by the BMS when it receives a signal that a short circuit fault has occurred in the power supply branch in the energy storage system loop. Exemplarily, the fault current of the power supply branch is greater than or equal to 210 A.

[0043] Specifically, when the BMS receives a signal that a short circuit fault has occurred in the energy storage system loop, if it detects that the fault current of the power supply branch is less than or equal to a preset current threshold, the first relay in the high-voltage box of the power supply branch sends a cut-off instruction to control the first relay to disconnect the power supply branch, thereby controlling the first relay to cut off the energy storage system loop under load, that is, controlling the first relay to force-cut off, thereby protecting the first relay and the high-voltage load in the energy storage system loop, and ensuring that the first relay covers the minimum breaking current of the first fuse, avoiding the problem that when the fault current of the power supply branch in the energy storage system loop is less than or equal to the preset current threshold, the first relay will cause adhesion due to exceeding the tolerance time and the high-voltage load will be destroyed due to long-term overload.

[0044] It should be noted that when the BMS detects that the fault current of the power supply branch is less than or equal to the preset current threshold, it directly sends a cut-off instruction to the first relay in the high-voltage box to realize forced cutting of the first relay in the power supply branch. Compared with the traditional method of sending a charge and discharge prohibition instruction to the target device (such as the energy storage inverter), that is, by cutting off the power to the target device, there may be a situation where the target device cannot be powered off. In this embodiment, by controlling the first relay to force cut off, that is, controlling the first relay to disconnect the power supply branch, the first relay is controlled to cut off the energy storage system loop with load, thereby protecting the first relay and the high-voltage load in the energy storage system loop.

[0045] It is worth noting that in actual application scenarios, the fault current in the power supply branch of the energy storage system circuit may have spikes, which can lead to misjudgment of fault current detection. Therefore, after detecting that the fault current in the power supply branch is less than or equal to a preset current threshold and delaying for a preset time, if the fault current is still less than or equal to the preset current threshold, a disconnection command is sent to the first relay in the high-voltage box to prevent misjudgment of fault current. The preset time can be 3 seconds, 4 seconds, etc.

[0046] 102. When the fault current is greater than the preset current threshold, the first fuse blows to disconnect the power supply branch.

[0047] Specifically, when the BMS detects that the fault current of the power supply branch is greater than a preset current threshold, the first fuse in the high-voltage box automatically blows, that is, the first fuse in the high-voltage box is disconnected first, thereby disconnecting the power supply branch and, in turn, disconnecting the energy storage system circuit, thereby protecting the energy storage system circuit. In addition, the first fuse is disconnected first before the first relay, eliminating the need to disconnect the first relay, thereby avoiding adhesion of the first relay, thereby protecting the battery pack, high-voltage load, and first relay in the energy storage system circuit, avoiding the need to replace the battery pack, facilitating maintenance of the energy storage system circuit, and improving the safety of the energy storage system circuit. It can be understood that in this embodiment, when the fault current of the power supply branch is detected to be greater than the preset current threshold, the first fuse is disconnected first, thereby protecting the battery pack in the energy storage system circuit, avoiding the maintenance cost and difficulty of replacing the battery pack, and protecting the energy storage system circuit to the greatest extent.

[0048] In this embodiment, when it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, a disconnection instruction is sent to the first relay to disconnect the power supply branch; when the fault current is greater than the preset current threshold, the first fuse is blown to disconnect the power supply branch, thereby achieving current matching between the first relay and the first fuse, thereby ensuring that the first relay and the first fuse achieve disconnection protection of the energy storage system circuit under a full range of fault currents, thereby avoiding the situation where the first relay in the high-voltage box cannot be disconnected and the first fuse cannot be blown when a fault current occurs in the power supply branch. It can be understood that this embodiment adopts corresponding disconnection methods based on the two comparison results between the fault current of the power supply branch and the preset current threshold, thereby achieving disconnection protection of the energy storage system circuit under a full range of fault currents, protecting the energy storage system circuit to the greatest extent, facilitating maintenance of the energy storage system circuit, and improving the safety of the energy storage system circuit operation.

[0049] In the above-mentioned energy storage system circuit protection method, by detecting that the fault current of the power supply branch is less than or equal to the preset current threshold, the first relay in the high-voltage box is cut off, and the first relay is controlled to disconnect the power supply branch, thereby controlling the first relay to cut off the energy storage system circuit under load; when the fault current of the power supply branch is greater than the preset current threshold, the first fuse is blown first to cut off the energy storage system circuit, thereby achieving current matching between the first relay and the first fuse, and further ensuring that the first relay and the first fuse achieve energy storage system circuit disconnection protection under the full range of fault currents, protecting the energy storage system circuit to the greatest extent, facilitating the maintenance of the energy storage system circuit, and improving the safety of the energy storage system circuit operation.

[0050] Furthermore, the preset current threshold is the peak current of the first relay.

[0051] Specifically, the preset current threshold is the peak current of the first relay. Therefore, when the fault current value of the power supply branch is greater than the peak current of the first relay, indicating that the fault current is too large, the first fuse in the high-voltage box will be disconnected first, disconnecting the power supply branch, thereby protecting the battery pack, the first relay, and the high-voltage load in the energy storage system circuit. When the fault current value of the power supply branch is less than the peak current of the first relay, indicating that the fault current is small, the first fuse will take a long time to melt. At this time, the BMS controls the first relay to cut off and control the first relay to force cut, thereby protecting the high-voltage relay and high-voltage load.

[0052] Furthermore, the energy storage system loop includes an energy storage converter, and the power supply branch is electrically connected to the energy storage converter. The method also includes: when it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, sending a charge and discharge prohibition instruction to the energy storage converter; if it is detected that the power of the energy storage converter is less than or equal to a first preset value and the current of the energy storage system loop is less than or equal to a second preset value, it is determined that the power supply branch is disconnected.

[0053] The energy storage system circuit includes a power conversion system (PCS) that controls the battery's charging and discharging processes, converting AC to DC, and directly powering AC loads in the absence of a power grid. The PCS is electrically connected to the power supply branch.

[0054] The charge and discharge prohibition instruction refers to an operation command to cut off the power supply branch by controlling the energy storage converter through the BMS.

[0055] The first preset value refers to the maximum power value of the energy storage converter when the power supply branch is disconnected. For example, the first preset value may be 0W (watt), 0.5W, etc. The second preset value refers to the maximum current value of the energy storage system loop when the power supply branch is disconnected. For example, the second preset value may be 0A, 0.1A, etc.

[0056] Specifically, when the fault current is less than or equal to a preset current threshold, the BMS sends a charge / discharge disable instruction to the energy storage converter. To detect whether the energy storage converter responds to the charge / discharge disable instruction, detection can be performed based on the power of the energy storage converter and the current of the energy storage system circuit. When it is detected that the power of the energy storage converter is less than or equal to a first preset value and the current of the energy storage system circuit is less than or equal to a second preset value, it indicates that the power of the energy storage converter has dropped below the first preset value and the current of the energy storage system circuit has dropped below the second preset value. At this point, it can be determined that the power supply branch is disconnected, that is, the energy storage converter responds to the charge / discharge disable instruction. It can be understood that in this embodiment, when the fault current of the power supply branch is less than or equal to the preset current threshold, the power supply branch is disconnected by controlling the energy storage converter to disable charge / discharge, thereby disconnecting the energy storage system circuit. This further protects the energy storage system circuit, reduces the frequency of load tripping of the first relay, and increases the service life of various electrical components.

[0057] Furthermore, a load switch is provided between the energy storage converter and the power supply branch, and the method further includes: if it is detected that within a first preset time, the power of the energy storage converter is greater than the first preset value and the current of the energy storage system loop is greater than the second preset value, then the load switch is controlled to disconnect to disconnect the power supply branch.

[0058] Among them, a load switch is set between the energy storage converter and the power supply branch to control the on and off of the power supply branch.

[0059] The first preset time is used to prevent misjudgment of whether the energy storage converter responds to the charge and discharge prohibition instruction. For example, the first preset time may be 3 seconds, 4 seconds, etc.

[0060] Specifically, to ensure the stability of the detected power of the energy storage converter and the current of the energy storage system circuit and to avoid misjudgment, detection is performed within a first preset time. If it is detected that the power of the energy storage converter is greater than a first preset value and the current of the energy storage system circuit is greater than a second preset value, indicating that the power of the energy storage converter is above the first preset value and the current of the energy storage system circuit is above the second preset value, it can be determined that the power supply branch is connected, that is, the energy storage converter has not responded to the charge and discharge prohibition instruction, that is, the control of the energy storage converter to prohibit charge and discharge and disconnect the power supply branch has failed. At this time, the BMS controls the load switch to disconnect to disconnect the power supply branch. It can be understood that in this embodiment, by providing a load switch between the energy storage converter and the power supply branch, the load switch can be used to disconnect the power supply branch when the BMS fails to control the energy storage converter to prohibit charge and discharge and disconnect the power supply branch, thereby further protecting the energy storage system circuit, reducing the frequency of the first relay's load disconnection, and increasing the service life of various electrical components.

[0061] Furthermore, controlling the load switch to disconnect includes: sending a tripping instruction to the load switch after a predetermined delay.

[0062] The trip command is an operation command to disconnect the power supply branch by controlling the load switch to trip. The predetermined time is a pre-set time used to prevent misjudgment of whether the power supply branch is disconnected. For example, the predetermined time can be 3 seconds, 4 seconds, etc.

[0063] Specifically, after a predetermined delay, a tripping instruction can be sent to the load switch through the BMS to control the load switch to perform tripping, thereby protecting the energy storage system circuit by controlling the load switch, reducing the frequency of load disconnection of the high-voltage relay, and increasing the service life of various electrical components.

[0064] Furthermore, the method further includes: if it is detected that the load switch does not respond to the tripping instruction within a second preset time, sending a cut-off instruction to the first relay to disconnect the power supply branch.

[0065] The second preset time is a time set in advance to prevent misjudgment of whether the load switch responds to the tripping instruction. For example, the second preset time may be 3 seconds, 4 seconds, etc.

[0066] Specifically, when it is detected that the load switch does not respond to the tripping instruction within the second preset time, that is, the load switch does not disconnect, in order to disconnect the power supply branch, the BMS sends a cut-off instruction to the first relay to disconnect the power supply branch, so as to achieve forced disconnection of the power supply branch by controlling the first relay, thereby protecting the energy storage system loop and improving the safety of the energy storage system loop.

[0067] like Figure 2 As shown, in one embodiment, a method for protecting a circuit of an energy storage system is provided, and the method specifically includes the following steps:

[0068] When it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, a cut-off instruction is sent to the first relay to disconnect the power supply branch;

[0069] When it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, a charge and discharge prohibition instruction is sent to the energy storage converter; if it is detected that the power of the energy storage converter is less than or equal to a first preset value and the current of the energy storage system loop is less than or equal to a second preset value, it is determined that the power supply branch is disconnected;

[0070] If it is detected that the power of the energy storage converter is greater than the first preset value and the current of the energy storage system loop is greater than the second preset value within the first preset time, the load switch is controlled to be disconnected to disconnect the power supply branch; wherein, controlling the load switch to be disconnected to disconnect the power supply branch includes: after a predetermined delay, sending a tripping instruction to the load switch;

[0071] If it is detected that the load switch does not respond to the tripping instruction within the second preset time, sending a cut-off instruction to the first relay to disconnect the power supply branch;

[0072] When the fault current is greater than the preset current threshold, the first fuse blows to disconnect the power supply branch.

[0073] Specifically, in one example, the fault current is greater than or equal to 210A, the preset current threshold 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. Figure 2 The figure is a flow chart of the energy storage system circuit protection method in this example.

[0074] The specific implementation of the above steps can refer to the steps of the above embodiments, and the embodiments of this application will not be repeated here.

[0075] Furthermore, the power supply branch includes a first power supply branch and a second power supply branch connected in parallel, and the method also includes: if it is detected that the fault current of the first power supply branch is less than or equal to a preset current threshold, sending a cut-off instruction to the first relay in the high-voltage box of the first power supply branch to disconnect the corresponding first power supply branch; and / or, if the fault current of the second power supply branch is greater than the preset current threshold, the first fuse in the high-voltage box of the second power supply branch is blown to disconnect the corresponding second power supply branch.

[0076] Specifically, the power supply branch includes a first power supply branch and a second power supply branch connected in parallel, and the protection method of the energy storage system loop may include the following situations: S1: the fault current of the first power supply branch is less than or equal to the preset current threshold, and the BMS sends a cut-off instruction to the first relay in the high-voltage box of the first power supply branch to disconnect the corresponding first power supply branch, or, when the fault current of the second power supply branch is greater than the preset current threshold, the first fuse in the high-voltage box of the second power supply branch blows to disconnect the corresponding second power supply branch. S2: the fault current of the first power supply branch is less than or equal to the preset current threshold, and the BMS sends a cut-off instruction to the first relay in the high-voltage box of the first power supply branch to disconnect the corresponding first power supply branch, and, when the fault current of the second power supply branch is greater than the preset current threshold, the first fuse in the high-voltage box of the second power supply branch blows to disconnect the corresponding second power supply branch.

[0077] It should be noted that, when the fault current of the first power supply branch is less than or equal to the preset current threshold, and the fault current of the second power supply branch is less than or equal to the preset current threshold, the BMS sends a cut-off command to the first relay in the high-voltage box of the first power supply branch to disconnect the corresponding first power supply branch. At the same time, the BMS also sends a cut-off command to the first relay in the high-voltage box 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 preset current threshold, and the fault current of the second power supply branch is greater than the preset current threshold, the first fuse in the high-voltage box of the first power supply branch blows to disconnect the corresponding first power supply branch. At the same time, the first fuse in the high-voltage box of the second power supply branch blows to disconnect the corresponding second power supply branch.

[0078] 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 circuit, in this embodiment, the first power supply branch and the second power supply branch are respectively disconnected according to the size of the fault current of the first power supply branch and the second power supply branch 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 circuit.

[0079] Furthermore, the energy storage system loop includes multiple power supply branches connected in parallel, and the method also includes: if the fault current of at least one power supply branch is greater than the preset current threshold, the first fuse in the high-voltage box of the corresponding power supply branch is blown to disconnect the corresponding power supply branch; and a disconnection instruction is sent to the first relay in other power supply branches to disconnect all power supply branches.

[0080] Specifically, the energy storage system loop includes multiple power supply branches connected in parallel. For a power supply branch with a fault current greater than a preset current threshold, the first fuse in the high-voltage box of the power supply branch blows to disconnect the corresponding power supply branch. For other power supply branches with a fault current less than or equal to the preset current threshold, the BMS sends a disconnection instruction to the first relay in the other power supply branches to disconnect all power supply branches, thereby achieving disconnection protection for all power supply branches and comprehensively protecting the energy storage system loop.

[0081] Furthermore, if Figure 3 As shown, it is a schematic block diagram of an energy storage system loop, wherein the energy storage system loop includes at least one battery pack, and the battery pack includes an input end and an output end; each of the battery packs includes a second fuse and at least one battery cell, and the second fuse and at least one battery cell are connected in series and are respectively connected to the input end and the output end; or, each of the battery packs includes at least one second fuse and at least one battery cell, and the second fuse and the battery cell are connected in series one by one and are respectively electrically connected to the input end and the output end to achieve parallel connection; the high-voltage box includes a first interface, a second interface, a third interface and a fourth interface, 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 respectively electrically connected to the target device; the method further includes: setting the melting speed of the first fuse to be greater than the melting speed of the second fuse.

[0082] The target device may be an energy storage converter.

[0083] Specifically, in the energy storage system circuit, the melting speed of the first fuse is set to be greater than the melting speed of the second fuse, thereby ensuring that the first fuse in the high-voltage box melts before the second fuse in the battery pack, that is, the melting sequence of the second fuse in the battery pack and the first fuse in the high-voltage box is matched, and because the first fuse melts first, the second fuse in the battery pack is protected, avoiding the maintenance cost and high maintenance difficulty caused by replacing the second fuse in the battery pack, and protecting the energy storage system circuit to the greatest extent.

[0084] In one example, if Figure 4The figure shows the melting time of the first fuse in the high-voltage box and the second fuse in the battery pack under different currents, as well as the withstand time of the first relay in the high-voltage box under different currents. As can be seen from the figure, if the preset current threshold is 3200A, when the fault current is ≤3200A, the first relay (corresponding to curve L1 in the figure) achieves the protection capability of the load disconnection circuit after 6 seconds through BMS control when the fault current is less than or equal to 3200A. When the fault current is greater than 3200A, the melting time of the second fuse in the battery pack (corresponding to curve L2 in the figure) is 0.18 seconds, which is greater than the melting time of the first fuse of 0.018 seconds. The first fuse takes precedence and thus protects the battery pack and the high-voltage box.

[0085] Please refer to Figure 3 An embodiment of the present application further provides an energy storage system circuit, which is protected by the energy storage system circuit protection method of any one of the above embodiments, wherein the energy storage system circuit includes at least one power supply branch, wherein the power supply branch includes: at least one battery pack, including an input end and an output end; a high-voltage box, including 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 a target device respectively; wherein the high-voltage box further includes 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; a first fusing current of the first fuse is greater than or equal to a first preset current and less than or equal to a second preset current, a first disconnecting current of the first relay is greater than or equal to a third preset current and less than or equal to a fourth preset current, and the fourth preset current is greater than or equal to the first preset current and less than the second preset current.

[0086] Among them, the first disconnecting current is the current used to disconnect the first relay, the first melting current is the current used to melt the first fuse, the current at which the first fuse is melted is set between the first preset current and the second preset current, the current at which the first relay is disconnected is set between the third preset current and the fourth preset current, and the fourth preset current is greater than or equal to the second preset current. It can not only directly use the first relay to cut off the power supply branch when a small fault current occurs in the power supply branch, but also directly use the first fuse to cut off the power supply branch when a large fault current occurs in the power supply branch, thereby reducing the maintenance cost of the energy storage system loop, and at the same time, it can also achieve global coverage of the fault current, avoiding the situation where the first relay in the high-voltage box cannot be disconnected and the first fuse cannot be melted when a fault occurs in the energy storage system loop.

[0087] Specifically, when it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, a cut-off instruction is sent to the first relay to disconnect the power supply branch; when the fault current is greater than the preset current threshold, the first fuse blows to disconnect the power supply branch. More specifically, when the BMS receives a signal that a short circuit fault has occurred in the energy storage system loop, when it detects that the fault current of the power supply branch is less than or equal to a preset current threshold, the first relay in the high-voltage box of the power supply branch sends a cut-off instruction to control the first relay to disconnect the power supply branch, thereby controlling the first relay to cut off the energy storage system loop under load, that is, controlling the first relay to forcibly cut off, thereby protecting the first relay and the high-voltage load in the energy storage system loop, and ensuring that the first relay covers the minimum breaking current of the first fuse, avoiding the problem that the fault current of the power supply branch in the energy storage system loop is less than or equal to the preset current threshold, the first relay will cause adhesion due to exceeding the tolerance time, and the high-voltage load will be destroyed due to long-term overload; when the BMS detects that the fault current of the power supply branch is greater than the preset current threshold, the first fuse in the high-voltage box will be disconnected first, so that the first relay will not stick, and the power supply branch will be disconnected, thereby protecting the high-voltage load and the first relay, without replacing the second fuse in the battery pack, facilitating the maintenance of the energy storage system loop, and improving the safety of the energy storage system loop.

[0088] It can be understood that in this embodiment, when it is detected that the fault current is greater than the preset current threshold, the first fuse is blown first, that is, the blowing sequence of the second fuse in the battery pack and the first fuse in the high-voltage box is matched, and because the first fuse is blown first, the second fuse in the battery pack is protected, thereby avoiding the maintenance cost and high maintenance difficulty caused by replacing the second fuse in the battery pack, protecting the energy storage system circuit to the greatest extent, improving the safety of the energy storage system circuit, and greatly reducing the difficulty of maintaining the energy storage system circuit.

[0089] Furthermore, the target device is an energy storage converter, and the energy storage system loop includes a load switch and multiple power supply branches; wherein, after the multiple power supply branches are connected in parallel, they are electrically connected to the energy storage converter through the load switch.

[0090] Specifically, one end of the load switch is electrically connected to the third and fourth interfaces of the high-voltage box in each power supply branch, respectively, and the other end of the load switch is electrically connected to the energy storage converter. By placing the load switch between the energy storage converter and the power supply branch, if the BMS fails to control the energy storage converter to disable charging and discharging and disconnect the power supply branch, the load switch can be used to disconnect the power supply branch. This further protects the energy storage system circuit, reduces the frequency of the first relay's load disconnection, and increases the service life of various electrical components.

[0091] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for protecting a circuit of an energy storage system, characterized in that: The energy storage system loop includes at least one power supply branch; wherein the power supply branch includes a high-voltage box, the high-voltage box includes a first fuse and a first relay, and the energy storage system loop protection method includes: When it is detected that the fault current of the power supply branch is less than or equal to the preset current threshold, a disconnection instruction is sent to the first relay to disconnect the power supply branch by controlling the first relay to perform forced disconnection and load disconnection; When the fault current is greater than the preset current threshold, the first fuse is blown to disconnect the power supply branch; The energy storage system loop includes an energy storage converter, the power supply branch is electrically connected to the energy storage converter, and when it is detected that the fault current of the power supply branch is less than or equal to a preset current threshold, a charge and discharge prohibition instruction is sent to the energy storage converter, and if it is detected that the power of the energy storage converter is less than or equal to a first preset value and the current of the energy storage system loop is less than or equal to a second preset value, it is determined that the power supply branch is disconnected; A load switch is provided between the energy storage converter and the power supply branch. If it is detected that the power of the energy storage converter is greater than the first preset value and the current of the energy storage system loop is greater than the second preset value within a first preset time, a tripping instruction is sent to the load switch after a predetermined delay to disconnect the power supply branch. If it is detected that the load switch does not respond to the tripping instruction within the second preset time, a disconnection instruction is sent to the first relay to disconnect the power supply branch by controlling the first relay to force disconnection and load disconnection.

2. The energy storage system circuit protection method according to claim 1, characterized in that: The preset current threshold is the peak current of the first relay.

3. The energy storage system circuit protection method according to any one of claims 1 to 2, characterized in that: The power supply branch includes a first power supply branch and a second power supply branch connected in parallel, and the method further includes: If it is detected that the fault current of the first power supply branch is less than or equal to the preset current threshold, a cut-off instruction is sent to the first relay in the high-voltage box of the first power supply branch to disconnect the corresponding first power supply branch; and / or, If the fault current of the second power supply branch is greater than a preset current threshold, the first fuse in the high-voltage box of the second power supply branch is blown to disconnect the corresponding second power supply branch.

4. The energy storage system circuit protection method according to any one of claims 1-2, characterized in that: The energy storage system loop includes a plurality of power supply branches connected in parallel, and the method further includes: If the fault current of at least one power supply branch is greater than the preset current threshold, the first fuse in the high-voltage box of the corresponding power supply branch is blown to disconnect the corresponding power supply branch; A disconnection instruction is sent to the first relays in other power supply branches to disconnect all power supply branches.

5. The energy storage system circuit protection method according to any one of claims 1 to 2, characterized in that: The energy storage system loop includes at least one battery pack, and the battery pack includes an input end and an output end; each of the battery packs includes a second fuse and at least one battery cell, and the second fuse and at least one battery cell are connected in series and are respectively connected to the input end and the output end; or, each of the battery packs includes at least one second fuse and at least one battery cell, and the second fuse and the battery cell are connected in series one by one and are respectively electrically connected to the input end and the output end to achieve parallel connection; the high-voltage box includes a first interface, a second interface, a third interface and a fourth interface, 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 respectively electrically connected to the target device; The method further comprises: The fusing speed of the first fuse is set to be greater than the fusing speed of the second fuse.

6. An energy storage system loop, characterized in that: The energy storage system circuit protection method according to any one of claims 1 to 5 is applied for protection, wherein the energy storage system circuit includes at least one power supply branch, wherein the power supply branch includes: at least one battery pack including an input terminal and an output terminal; 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, 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; Wherein, the high-voltage box further includes a first fuse and a first relay, 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; The first fusing current of the first fuse is greater than or equal to a preset first preset current and less than or equal to a second preset current, the first disconnecting current of the first relay is greater than or equal to a third preset current and less than or equal to a fourth preset current, and the fourth preset current is greater than or equal to the first preset current and less than the second preset current.

7. The energy storage system circuit according to claim 6, characterized in that: The target device is an energy storage converter, and the energy storage system loop includes a load switch and a plurality of power supply branches; Among them, after the multiple power supply branches are connected in parallel, they are electrically connected to the energy storage converter through the load switch.

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