Protection method of energy storage system and energy storage system

Abstract

The embodiment of the invention discloses an energy storage system protection method and an energy storage system. The energy storage system comprises at least one power supply branch, the power supply branch comprises at least one battery pack and a high-voltage box, and the high-voltage box comprises a first switching device and a first fuse. Disconnecting the first switching device to cut off the power supply branch; and when the ratio of the detected fault current to the rated current is greater than the first threshold value, the first fuse is fused to cut off the power supply branch, so that global range fault protection of the energy storage system can be realized, a protection blind area of a protection device in the high-voltage box is avoided, and the safety performance of the energy storage system is improved.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a protection method for an energy storage system and an energy storage system. Background Technology

[0002] As the capacity of energy storage cells gradually increases and the charge / discharge rate improves, the current-carrying capacity required for energy storage systems also becomes increasingly demanding. Therefore, the selection of protection devices in energy storage systems is particularly important. Generally, short-circuit protection is achieved by installing protection devices in a high-voltage box. However, the protection devices in the high-voltage box have protection blind spots and cannot effectively protect the energy storage system. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a protection method and energy storage system for energy storage systems, aiming to solve the technical problem that protection devices in high-voltage boxes cannot effectively protect energy storage systems in the prior art.

[0004] To address the aforementioned problems, in a first aspect, this application provides a protection method for an energy storage system. The energy storage system includes at least one power supply branch, which includes at least one battery pack and a high-voltage box. The high-voltage box includes a first switching device and a first fuse. The method includes:

[0005] If the ratio between the fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold, the first switching device is disconnected to cut off the power supply branch.

[0006] If the ratio between the detected fault current and the rated current is greater than the first threshold, the first fuse will blow to cut off the power supply branch.

[0007] Secondly, this application also provides an energy storage system, which includes at least one power supply branch, the power supply branch including:

[0008] At least one battery pack;

[0009] A high-voltage box, a first fuse, and a first switching device, wherein the first switching device is provided with a first terminal and a second terminal;

[0010] The interface group includes the first interface, the second interface, the third interface, and the fourth interface;

[0011] Wherein, the first end is electrically connected to one end of the first fuse, the other end of the first fuse is electrically connected to one end of the first interface, the second end is electrically connected to one end of the third interface, and one end of the second interface is electrically connected to one end of the fourth interface; or, the first end is electrically connected to one end of the first interface, the second end is electrically connected to one end of the third interface, one end of the first fuse is electrically connected to one end of the second interface, and the other end of the first fuse is electrically connected to one end of the fourth interface.

[0012] The other ends of the first interface and the second interface are electrically connected to the two ends of the battery pack, respectively; the other ends of the third interface and the fourth interface are electrically connected to the first bus and the second bus of the energy storage system, respectively.

[0013] The energy storage system is protected using the protection method for energy storage systems provided in the first aspect.

[0014] The energy storage system protection method provided in this application disconnects the first switching device to cut off the power supply branch when the ratio between the detected fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold; and blows the first fuse to cut off the power supply branch when the detected fault current is greater than the first threshold. This method can achieve global fault protection for the energy storage system, avoid the existence of protection blind spots in the protection devices in the high-voltage box, and improve the safety performance of the energy storage system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a first internal circuit diagram of a high-voltage box provided in an embodiment of this application;

[0017] Figure 2 This is a second internal circuit diagram of a high-voltage box provided in an embodiment of this application;

[0018] Figure 3 This is a third internal circuit diagram of a high-voltage box provided in an embodiment of this application;

[0019] Figure 4 Protection curves of circuit breakers and fuses in high-voltage boxes provided in embodiments of this application;

[0020] Figure 5 The fourth internal circuit diagram of the high-voltage box provided in the embodiments of this application;

[0021] Figure 6 The fifth internal circuit diagram of the high-voltage box provided in the embodiments of this application;

[0022] Figure 7 The sixth internal circuit diagram of the high-voltage box provided in the embodiments of this application;

[0023] Figure 8 A first architecture diagram illustrating the connection between the high-voltage box and the battery management system provided in an embodiment of this application;

[0024] Figure 9 This is a second architecture diagram showing the connection between the high-voltage box and the battery management system provided in an embodiment of this application;

[0025] Figure 10 A schematic block diagram of an energy storage system provided in an embodiment of this application;

[0026] Figure 11 A flowchart illustrating the protection method for an energy storage system provided in this application embodiment. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0029] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0030] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0031] Furthermore, in this application, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication between two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific implementation.

[0032] In related technologies, high-voltage boxes in energy storage systems typically rely on a combination of disconnect switches, fuses, and relays for fault protection. However, this approach has increasingly revealed its drawbacks. The minimum breaking capacity of fuses is usually 8 to 10 times their rated current. For example, a 500A fuse can only break a fault current of 4000A or higher. However, the maximum breaking capacity of relays is currently 2000A, and disconnect switches can only isolate fault currents they can withstand. This results in a protection blind zone for fault currents between 2000A and 4000A in the energy storage system, reducing the reliability of the energy storage system and posing safety hazards.

[0033] Specifically, when a small fault current occurs in the energy storage system, it can be interrupted by a relay; when a large short-circuit fault current occurs, it can be interrupted by a fuse. The main function of a disconnecting switch is to provide reliable electrical isolation and a visible disconnect point. It has strong short-circuit withstand capability but cannot be operated under load. Therefore, in the high-voltage box, only relays and fuses are used as devices to interrupt fault currents.

[0034] As the current in energy storage charging and discharging systems increases, the protection blind zone between relays and fuses gradually becomes more apparent. The maximum breaking current of a relay under rated voltage is 2kA, while the minimum breaking current of a fuse is typically 8In to 10In (i.e., 8 to 10 times the rated current, where the rated current is the fuse's rated current). When the minimum breaking current of a fuse is set to 5In, if the fuse's rated current In > 400A, then 5In > 2kA, resulting in a protection blind zone that prevents breaking, thereby reducing the reliability of the energy storage system and posing a safety hazard.

[0035] To address this, this application provides a high-voltage box installed in the power supply branch of an energy storage system. The power supply branch includes at least one battery pack and the high-voltage box. The high-voltage box includes a first fuse, a first switching device, and an interface group. The first switching device includes a first terminal, a second terminal, a third terminal, and a fourth terminal. The interface group includes a first interface, a second interface, a third interface, and a fourth interface. The first fuse and the first switching device are located in the main circuit of the high-voltage box. The rated current of the first fuse is set to be less than or equal to a preset first current. The product of the first breaking capacity of the first fuse and the first current is less than or equal to the first breaking current of the first switching device. This avoids protection blind spots in the protection devices of the high-voltage box. Furthermore, the first switching device can be used for protection when a small fault current occurs in the energy storage system, and the first fuse can be used for protection when a large fault current occurs. This achieves global fault protection for the energy storage system and improves the safety performance of the energy storage system.

[0036] Please see Figure 1 and Figure 2, Figure 1 This is a first internal circuit diagram of a high-voltage box provided in an embodiment of this application; Figure 2 This is a second internal circuit diagram of a high-voltage box provided in an embodiment of this application.

[0037] like Figure 1 and Figure 2 As shown, this application provides a high-voltage box 10, which is disposed in the power supply branch 1 of an energy storage system. The power supply branch 1 includes at least one battery pack 20 and the high-voltage box 10; the high-voltage box 10 includes:

[0038] First fuse FU+;

[0039] The first switching device K1 has a first terminal A and a second terminal B, and the first terminal A is electrically connected to one end of the first fuse FU+.

[0040] The interface group includes interface B+, interface B-, interface P+, ​​and interface P-.

[0041] Wherein, the first end A is electrically connected to one end of the first fuse FU+, the other end of the first fuse FU+ is electrically connected to one end of the first interface B+, the second end B is electrically connected to one end of the third interface P+, ​​and one end of the second interface B- is electrically connected to one end of the fourth interface P-; or, the first end A is electrically connected to one end of the first interface B+, the second end B is electrically connected to one end of the third interface P+, ​​one end of the first fuse FU+ is electrically connected to one end of the second interface B-, and the other end of the first fuse FU+ is electrically connected to one end of the fourth interface P-;

[0042] The other ends of the first interface B+ and the second interface B- are electrically connected to the two ends of the battery pack 20, respectively; the other ends of the third interface P+ and the fourth interface P- are electrically connected to the first bus and the second bus, respectively.

[0043] Wherein, the rated current of the first fuse FU+ is less than or equal to the first current, and the product between the first breaking ratio of the first fuse FU+ and the first current is less than or equal to the first breaking current of the first switching device K1.

[0044] In this application, the first fuse FU+ can be a conventional passive fuse or a Pyro fuse, i.e., a smart fuse. The first breaking capacity can be understood as the minimum breaking capacity of the first fuse FU+. The first switching device K1 can be one or more of a circuit breaker QF, a disconnector, a fusion switch QF1, and a relay. At least one of the circuit breaker QF, the disconnector, and the fusion switch QF1 can be equipped with a tripping device. The first breaking current can be understood as the maximum breaking current of the first switching device K1.

[0045] The breaking current of the first fuse FU+ can be obtained by multiplying the rated current of the first fuse FU+ by its breaking capacity. Since the rated current of the first fuse FU+ provided in this application is less than or equal to the first current, and the product of the first breaking capacity of the first fuse FU+ and the first current is less than or equal to the first breaking current of the first switching device K1, the product of the first breaking capacity of the first fuse FU+ and the rated current of the first fuse FU+ must also be less than or equal to the first breaking current of the first switching device K1. That is, the minimum breaking current of the first fuse FU+ is less than or equal to the first breaking current of the first switching device K1, thereby avoiding the existence of a protection blind zone in the power supply branch where the high-voltage box is located, and thus improving the safety and reliability of the energy storage system. The first current can be 400A.

[0046] The high-voltage box 10 provided in this application includes a first fuse FU+, a first switching device K1, and an interface group. The first switching device K1 has a first terminal A and a second terminal B. The interface group includes a first interface B+, a second interface B-, a third interface P+, ​​and a fourth interface P-. The first fuse FU+ and the first switching device K1 are located in the main circuit of the high-voltage box 10. The rated current of the first fuse FU+ is set to be less than or equal to a first current, and the product between the first breaking capacity of the first fuse FU+ and the first current is less than or equal to the first breaking current of the first switching device K1. This avoids the existence of protection blind spots in the protection devices in the high-voltage box. Thus, when a small fault current occurs in the energy storage system, the first switching device K1 can be used for protection, and when a large fault current occurs, the first fuse FU+ can be used for protection. This achieves global fault protection for the energy storage system and improves the safety performance of the energy storage system.

[0047] In some embodiments, the first breaking capacity of the first fuse FU+ is less than or equal to a preset first threshold, the first breaking current of the first switching device K1 is greater than or equal to a preset second current, and the ratio between the second current and the rated current of the first fuse FU+ is greater than or equal to the first threshold and less than or equal to the second breaking capacity of the first fuse.

[0048] Specifically, the first breaking capacity ratio can be understood as the minimum breaking capacity ratio of the first fuse FU+, and the second breaking capacity ratio can be understood as the maximum breaking capacity ratio of the first fuse FU+. This application sets the minimum breaking capacity ratio of the first fuse FU+ to be less than or equal to a preset first threshold, while the first threshold is less than or equal to the ratio between the second current and the rated current of the first fuse FU+. The first breaking capacity ratio of the first fuse FU+ is less than or equal to the first threshold, and the ratio between the second current and the rated current of the first fuse FU+ is less than or equal to the second breaking capacity ratio of the first fuse. Therefore, when the fault current of the energy storage system is less than or equal to the second current, the first switching device K1 is used for protection, and when the fault current is greater than the second current, the first fuse FU+ is used for protection. This achieves global fault protection for the energy storage system, avoids blind spots in the protection devices of the high-voltage box 10, and improves the safety performance of the energy storage system.

[0049] Meanwhile, the minimum breaking capacity of the first fuse FU+ mentioned in this application can be determined by the ratio between the minimum breaking current of the first fuse FU+ and its rated current. The first threshold can be 5, and the second current can be 5000A.

[0050] In some embodiments, when the fault current of the high-voltage box 10 is less than or equal to the second current, the breaking speed of the first fuse FU+ is less than or equal to the breaking speed of the first switching device K1; when the fault current is greater than the second current, the breaking speed of the first fuse FU+ is greater than the breaking speed of the first switching device K1.

[0051] In this application, when the fault current of the high-voltage box 10 is less than or equal to the second current, the breaking speed of the first fuse FU+ is less than or equal to the breaking speed of the first switching device K1. This allows the first switching device K1 to break first, thus preventing the first fuse FU+ from breaking before the first switching device K1. This reduces the number of times the first fuse FU+ needs to be replaced. At the same time, when the fault current is greater than the second current, the breaking speed of the first fuse FU+ is greater than the breaking speed of the first switching device K1. This ensures that when the fault current is greater than the second current, the first fuse FU+ is used first to break, thus preventing the failure of the first switching device K1 from preventing the main circuit of the high-voltage box 10 from being cut off.

[0052] In some embodiments, such as Figure 3 , Figure 5 and Figure 6As shown, the first switching device K1 includes a circuit breaker QF, a disconnector QS, a fusion switch QF1, or a second fuse FU-; wherein, the first terminal A and the second terminal B are provided on the circuit breaker QF, the disconnector QS, the fusion switch QF1, or the second fuse FU-; when the fault current of the high-voltage box 10 is less than or equal to the second current, the breaking speed of the circuit breaker QF, the breaking speed of the disconnector QS, the breaking speed of the fusion switch QF1, or the breaking speed of the second fuse FU- is greater than or equal to the breaking speed of the first fuse FU+.

[0053] Specifically, this application can use circuit breaker QF, disconnector QS, fusion switch QF1, or second fuse FU- as the first switching device K1. Then, when the fault current of the high-voltage box 10 is less than or equal to the second current, the breaking speed of circuit breaker QF, disconnector QS, fusion switch QF1, or second fuse FU- can be used to disconnect the main circuit of the high-voltage box 10. When the fault current of the high-voltage box 10 is greater than the second current, the first fuse FU+ can be used to disconnect the main circuit of the high-voltage box 10, thus achieving global fault protection for the energy storage system and improving the safety performance of the energy storage system.

[0054] It should be noted that the second fuse FU- can be a smart fuse. The second fuse FU- can be used as the first switching device K1 or can be used independently of the first switching device K1. It can be selected according to the actual application, and this application does not make specific limitations.

[0055] In some embodiments, such as Figure 3 , Figure 5 and Figure 6 As shown, the circuit breaker QF, the disconnector QS, or the fusion switch QF1 is equipped with a tripping device. The ratio between the instantaneous tripping current and the rated current of the circuit breaker QF, or the ratio between the instantaneous tripping current and the rated current of the disconnector QS, or the ratio between the instantaneous tripping current and the rated current of the fusion switch QF1 is greater than or equal to a preset second threshold and less than or equal to a preset third threshold.

[0056] In this application, the circuit breaker QF, disconnector QS, or fusion switch QF1 is equipped with a tripping device to interrupt fault current in the energy storage system. A tripping device is an electrical protection device that automatically triggers a switch (such as a circuit breaker QF, contactor, etc.) to disconnect the circuit when abnormal conditions such as overload, short circuit, or undervoltage occur, thereby protecting the circuit and equipment from damage. Common tripping devices include thermal trip units, electromagnetic trip units, and composite trip units (i.e., electronic trip units). Thermal trip units utilize the thermal effect of current, triggering the tripping mechanism through the deformation of a bimetallic strip, and are suitable for overload protection. Electromagnetic trip units utilize the magnetic effect of current, triggering the tripping mechanism through the magnetic field generated by an electromagnet, and are suitable for short circuit protection. Composite trip units combine thermal and electromagnetic tripping functions, providing dual protection against overload and short circuit. Electronic trip units use electronic circuits to detect changes in current and voltage, controlling the tripping mechanism through electronic signals, offering higher accuracy and flexibility.

[0057] Specifically, this application sets the ratio between the instantaneous tripping current and the rated current of circuit breaker QF, or the ratio between the instantaneous tripping current and the rated current of disconnector QS, or the ratio between the instantaneous tripping current and the rated current of fusion switch QF1 to be no less than a second threshold and no greater than a third threshold. This allows the first switching device K1 to trip when the fault current is less than or equal to the second current. The second threshold can be 5, and the third threshold can be 10.

[0058] Furthermore, in some embodiments, the second threshold is less than or equal to the first threshold, and the first threshold is less than or equal to the third threshold.

[0059] Specifically, this application sets the first threshold between the second and third thresholds, thereby enabling protection by using a circuit breaker QF, a disconnector QS, or a fusion switch QF1 when the fault current of the energy storage system is equal to or greater than the second current, and by using a first fuse FU+ when the fault current is greater than the second current. This achieves global fault protection for the energy storage system, avoids blind spots in the protection devices in the high-voltage box 10, and improves the safety performance of the energy storage system.

[0060] In some embodiments, such as Figure 3 As shown, the circuit breaker QF has a first terminal A, a second terminal B, a third terminal C, and a fourth terminal D. The circuit breaker QF is equipped with a tripping device; the third terminal C is electrically connected to one end of the second interface B-, and the fourth terminal D is electrically connected to one end of the fourth interface P-.

[0061] Specifically, in the process of selecting the circuit breaker QF, this application, such as Figure 4As shown, the tripping curve of circuit breaker QF can be matched with the pre-arc curve of the first fuse FU+. The curve of the first fuse FU+ shows a slower initial action and a faster later action, while the tripping curve of circuit breaker QF shows thermal tripping in the early stage, a slower initial action and a faster later action, and finally magnetic tripping. The tripping time is fixed. Figure 4 As can be seen from the data, the intersection of the two curves is 5kA. When the fault current is ≤5kA, the tripping curve of the circuit breaker QF acts faster, and the fault current is protected by the circuit breaker QF. When the fault current is >5kA, the arc-preceding curve of the fuse acts faster, and the fault current is protected by the fuse.

[0062] It should be noted that, Figure 4 The current at the intersection of the two curves exceeds the minimum breaking current of the fuse. This application uses a combination of circuit breaker QF and first fuse FU+ to eliminate protection blind spots and achieve full-range fault protection for the energy storage system. Furthermore, the circuit breaker QF must be UL and IEC certified during the selection process.

[0063] In some embodiments, such as Figure 5 As shown, the disconnector switch QS has a first terminal A, a second terminal B, a third terminal C, and a fourth terminal D. The disconnector switch QS is equipped with a tripping device; the third terminal C is electrically connected to one end of the second interface B-, and the fourth terminal D is electrically connected to one end of the fourth interface P-.

[0064] In this application, the disconnector switch QS is widely used due to its strong withstand capability, but it lacks breaking capacity. Therefore, this application upgrades the disconnector switch QS by replacing it with a disconnector switch QS equipped with a tripping device. This allows the disconnector switch to have a strong breaking capacity similar to that of the circuit breaker QF while retaining its strong withstand capability. Thus, when the fault current of the energy storage system is equal to or greater than the second current, the disconnector switch QS can be used for protection, and when the fault current is greater than the second current, the first fuse FU+ can be used for protection. This enables global fault protection for the energy storage system, avoids protection blind spots in the protection devices of the high-voltage box 10, and improves the safety performance of the energy storage system.

[0065] Meanwhile, the breaking capacity of the disconnecting switch QS mentioned in this application must be at least greater than the maximum short-circuit current of the high-voltage cluster and the minimum breaking current of the fuse.

[0066] In addition, after the disconnector switch QS is upgraded to a disconnector switch with a tripping device, it can also be equipped with a shunt trip accessory function to achieve linkage with the battery management system. When the battery management system detects a fault current exceeding a certain threshold, for example, a fault current ≥ 1.3 times the rated current of the first fuse FU+, the battery management system executes a tripping procedure, which can drive the disconnector switch QS to shunt trip and disconnect the faulty circuit.

[0067] It should be noted that the delay time involved in the process from the battery management system receiving a fault signal to issuing a command to the trip unit receiving the signal and starting to execute it must be less than the pre-arc fuse time of the first fuse FU+. At the same time, the pre-arc curve current value of the fuse corresponding to the delay time must be less than the minimum breaking current of the first fuse FU+.

[0068] In some embodiments, such as Figure 1 and Figure 2 As shown, one end of the second fuse FU- is electrically connected to one end of the second interface B-, and the other end of the second fuse FU- is electrically connected to one end of the fourth interface P-.

[0069] In this application, the first fuse FU+ is located between the first interface B+ and the third interface P+, ​​and the second fuse FU- is located between the second interface B- and the fourth interface P-. The first fuse FU+ and the second fuse FU- can be the main and negative fuses in the high-voltage box 10, thereby providing more reliable circuit protection for the high-voltage box 10 and ensuring that the circuit in the high-voltage box 10 can be effectively cut off under different fault conditions.

[0070] Furthermore, in some embodiments, when the fault current of the high-voltage box 10 is less than or equal to the second current, the breaking speed of the second fuse FU- is greater than or equal to the breaking speed of the first switching device K1; when the fault current is greater than the second current, the breaking speed of the second fuse FU- is less than the breaking speed of the first switching device K1.

[0071] In this application, the first fuse FU+ and the second fuse FU- can be a smart fuse and a traditional passive fuse, respectively. That is, this application can adjust the two traditional passive fuses at the positive and negative poles in the high-voltage box 10 to Pyro fuses and traditional passive fuses. Traditional passive fuses have a significant advantage in melting quickly when the short circuit current is large, but they have limitations in melting when the short circuit current is small, and they cannot melt in time, or even if the melting time is too long, there is a risk of tube explosion.

[0072] Therefore, this application replaces the two conventional passive fuses at the positive and negative terminals inside the high-voltage box 10 with Pyro fuses and conventional passive fuses, which can solve the risk of blank protection for small short-circuit currents. The Pyro fuse, also known as a smart fuse, is an integrated active and passive device. When any fault current occurs, the battery management system detects the fault current signal and sends an excitation signal to the Pyro fuse. Upon receiving the external excitation signal, the Pyro fuse activates the igniter, cutting off the internal connection circuit, thereby achieving rapid interruption of the circuit current.

[0073] In addition, Pyro fuses can internally detect fault currents and send excitation signals to trigger the circuit, forming an integrated active and passive protection scheme to ensure the safety and reliability of the energy storage system. When selecting Pyro fuses, they must possess certifications such as UL and IEC.

[0074] In some embodiments, such as Figure 6 and Figure 7 As shown, the fusion switch QF1 has a first terminal A, a second terminal B, a third terminal C, and a fourth terminal D. The third terminal C is electrically connected to one end of the second interface B-, and the fourth terminal D is electrically connected to one end of the fourth interface P-.

[0075] Specifically, this application can cover the minimum breaking capacity of the first fuse FU+ by setting a fusion switch QF1 in the high-voltage box 10. At the same time, the fusion switch QF1 adopts a modular design, which can reduce the size of the high-voltage box 10 and achieve the purpose of reducing the cost of the energy storage system.

[0076] Furthermore, in some embodiments, the second breaking current of the fusion switch QF1 is greater than or equal to the second current.

[0077] In this application, the second breaking current can be understood as the maximum breaking current of the fusion switch QF1. The main contacts of the fusion switch QF1 can replace the power-on and power-off functions of the relay in the high-voltage box 10. The breaking capacity of the fusion switch QF1 can reach 20kA, which is greater than 2kA. This avoids the limitation of the relay's breaking capacity. When the fault current of the energy storage system is equal to or equal to the second current, the fusion switch QF1 is used for protection. When the fault current is greater than the second current, the first fuse FU+ is used for protection. This enables global fault protection of the energy storage system, avoids the protection blind zone of the protection devices in the high-voltage box 10, and improves the safety performance of the energy storage system.

[0078] Furthermore, in some embodiments, the third breaking current of the first fuse FU+ is less than or equal to a preset third current, the third breaking current is greater than the first breaking current, and the second breaking current of the fusion switch QF1 is greater than or equal to the third current.

[0079] In this application, the third breaking current can be understood as the maximum breaking current of the first fuse FU+. The maximum breaking current of the first fuse FU+ is less than or equal to the preset third current. At the same time, the second breaking current of the fusion switch QF1, that is, the maximum breaking current of the fusion switch QF1, can be greater than or equal to the third current. Therefore, when performing full-area protection of the energy storage system, only the fusion switch QF1 can be used for protection, thereby reducing the number of fuse replacements in the high-voltage box 10.

[0080] In some embodiments, such as Figure 6 As shown, the tripping device provided with the fusion switch QF1 may include a motor tripping device and / or a shunt tripping device.

[0081] In this application, the fusion switch QF1 may be equipped with accessories such as a motor trip device and / or a shunt trip device. Both the motor trip device and the shunt trip device can realize remote tripping operation. The circuits of the motor trip device and the shunt trip device are independent, thereby realizing the tripping redundancy control function. In this way, the fusion switch QF1 can be guaranteed to operate normally in the event of power loss or a single fault in the active circuit.

[0082] Meanwhile, the protection mechanism of the integrated switch QF1 is similar to that of the circuit breaker QF protection. Both the motor tripping device and the shunt tripping device can be linked with the battery management system's protection strategy. When the battery management system detects a fault current exceeding a certain threshold, for example, a fault current ≥ 1.3 times the rated current of the first fuse FU+, the battery management system executes a tripping procedure, which can activate the motor tripping device or the shunt tripping device within the integrated switch QF1 to disconnect the faulty circuit. The integrated switch QF1 must possess UL, IEC, and other certifications during the selection process.

[0083] In some embodiments, such as Figure 6 and Figure 7 As shown, the fusion switch QF1 is equipped with a first relay KM+. One end of the first relay KM+ is electrically connected to the first terminal A, and the other end of the first relay KM+ is electrically connected to the second terminal B.

[0084] In this application, the first relay KM+ can be the main positive relay inside the high-voltage box 10. The main positive relay is used to control the on / off state of the high-voltage circuit, ensuring that the circuit can be quickly cut off when needed to prevent faults such as overload and short circuit. At the same time, before the main relay operates, a self-test is performed through the pre-charge circuit to prevent the large current at the moment of power-on from damaging other electronic components in the high-voltage system.

[0085] Specifically, the first relay KM+ is located within the fusion switch QF1, meaning that the first relay KM+ can be integrated into the fusion switch QF1. The main positive contact of the fusion switch QF1 can replace the function of the first relay KM+. Thus, when the fault current of the energy storage system is equal to or equal to the second current, the first relay KM+ integrated into the fusion switch QF1 can be used for protection. When the fault current is greater than the second current, the first fuse FU+ can be used for protection. This enables global fault protection for the energy storage system, avoids blind spots in the protection devices in the high-voltage box 10, and improves the safety performance of the energy storage system.

[0086] It should be noted that the first relay KM+ can also be independent of the fusion switch, and it can be selected according to the actual application. This application does not make any specific restrictions.

[0087] In some embodiments, such as Figure 6 and Figure 7 As shown, the high-voltage box 10 also includes a pre-charging circuit, the two ends of which are electrically connected to the two ends of the first relay KM+.

[0088] In this application, a pre-charging circuit can be provided inside the high-voltage box 10. The pre-charging circuit can cooperate with the first relay KM+ to enable the high-voltage box 10 to be powered on.

[0089] In some embodiments, the pre-charging circuit includes a pre-charging relay KM and a pre-charging resistor R; wherein, one end of the pre-charging relay KM is electrically connected to one end of the first relay KM+ and one end of the first fuse FU+, the other end of the pre-charging relay KM is electrically connected to one end of the pre-charging resistor R, and the other end of the pre-charging resistor R is electrically connected to the other end of the first relay KM+ and the second end B.

[0090] Furthermore, in some embodiments, such as Figure 6 and Figure 7 As shown, the precharge relay KM is located inside the fusion switch QF1.

[0091] In this application, the pre-charge relay KM can also be integrated into the fusion switch QF1, so that when the high-voltage box 10 needs to be powered on, the fusion switch QF1 can be used to power on, thereby avoiding damage to electronic components.

[0092] In some embodiments, such as Figure 6 and Figure 7 As shown, the high-voltage box 10 also includes a second relay KM-, one end of the second relay KM- is electrically connected to one end of the second interface B-, and the other end of the second relay KM- is electrically connected to the third terminal C.

[0093] In this application, the second relay KM- can be the main negative relay in the high-voltage box 10. The main negative relay is a key relay on the negative side of the high-voltage system. The operation of the main negative relay is usually completed in conjunction with the pre-charging circuit and the main positive relay. The main negative relay is responsible for connecting the negative terminal of the battery to the negative terminal of the external load or charger. At the same time, by controlling the closing and opening of the main negative relay, it can be determined whether the high-voltage circuit forms a closed loop, thereby realizing the on-off control of the high-voltage circuit.

[0094] In some embodiments, such as Figure 6 and Figure 7 As shown, the second relay KM is located inside the fusion switch QF1.

[0095] In this application, the second relay KM- can be integrated into the fusion switch QF1. The main negative contact of the fusion switch QF1 can replace the function of the second relay KM-, and thus can power on the high voltage box 10 together with the first relay KM+ and the pre-charging circuit.

[0096] Furthermore, this application can integrate the first relay KM+, the second relay KM-, and the pre-charge relay KM into the fusion switch QF1, thereby reducing the size of the high-voltage box 10. For example... Figure 8 and Figure 9 As shown, Figure 8 This is a schematic diagram showing the connection between the first relay KM+, the second relay KM-, and the precharge relay KM, which are not integrated into the fusion switch QF1, and the main control board of the battery management system. Figure 9 This diagram shows the integration of the first relay KM+, the second relay KM-, and the precharge relay KM within the fusion switch QF1, and their connection to the main control board of the battery management system.

[0097] Traditional solutions require one disconnecting switch, two main negative relays, two fuses, one pre-charge relay KM, one pre-charge resistor R, and one Hall sensor HALL. However, by integrating the first relay KM+, the second relay KM-, and the pre-charge relay KM into the fusion switch QF1, only one disconnecting switch, two fuses, one pre-charge resistor R, and one Hall sensor HALL are needed. Therefore, it can be seen that the use of the fusion switch QF1 in this application can reduce the structural complexity of the high-voltage box 10 and also reduce installation time, thereby achieving the goal of saving costs for the energy storage system.

[0098] At the same time, from Figure 8 and Figure 9As can be seen, the traditional battery management system has a total of 7 interfaces in its control loop: 4 high-side drivers and 3 DI interfaces. In contrast, the QF1 integrated switch solution only requires 4 interfaces: 3 high-side drivers and 1 DI interface. It can be seen that using the QF1 integrated switch can save 3 interfaces and also optimize the control circuit.

[0099] The control circuit principle of the traditional battery management system is as follows: the coil drives of the main positive and negative relays, precharge relay KM, shunt intermediate relay, etc. are all controlled by the high-side drive signal of the battery management system to turn on and off, that is, on when high level, off when low level; the auxiliary contacts of the main positive and negative relays and circuit breaker QF are connected to the DI feedback signal interface of the battery management system to identify the switching status of the main positive and negative relays and circuit breaker QF; the shunt tripping function of circuit breaker QF is driven by the contacts of the shunt intermediate relay, which solves the problem of insufficient direct drive power of the battery management system.

[0100] The control circuit principle of the battery management system (BMS) using the integrated switch QF1 scheme is as follows: The integrated switch QF1 contains a main charging switch and a pre-charging switch, which are controlled by a motor trip to open and close. The opening and closing time can be 2 seconds. The high-side drive point of the BMS continuously sends a high-level signal (greater than 2 seconds) to the internal electric operating mechanism of the integrated switch QF1 for 3 seconds. The high level is between 19.2V and 28.8V, and the low level is between 0V and 4.5V. The high and low level strategies are as follows: Low level input to both the main charging switch and the pre-charging switch: pre-charging fully open, main charging fully open; low level input to both the main charging switch and the pre-charging switch: pre-charging closed, main charging fully open; high level input to both the main charging switch and the pre-charging switch: pre-charging closed, main charging fully open; high level input to both the main charging switch and the pre-charging switch: pre-charging fully open, main charging closed. It can be seen that the control circuit of the BMS using the integrated switch QF1 scheme in this application requires fewer control points, has a lower failure rate, and a simpler execution strategy.

[0101] In some embodiments, such as Figure 2 As shown, the high-voltage box 10 also includes a shunt SH, which is located on the line between the first interface B+ and the third interface P+, ​​or on the line between the second interface B- and the fourth interface P-.

[0102] In some embodiments, such as Figure 7 As shown, the high-voltage box 10 also includes a Hall sensor HALL, which is located on the line between the first interface B+ and the third interface P+, ​​or on the line between the second interface B- and the fourth interface P-.

[0103] Specifically, this application enables current acquisition of the battery cluster located in the high-voltage box 10 by installing a shunt SH and / or a Hall sensor HALL inside the high-voltage box 10. Simultaneously, the shunt SH and / or the Hall sensor HALL can be placed at the negative terminal, where the negative potential is lower, isolation requirements are less stringent, circuit design is simpler, cost may be lower, and the risk of electric shock or short circuit can be reduced.

[0104] In some embodiments, such as Figure 10 As shown, this application also provides an energy storage system, which includes at least one power supply branch 1, the power supply branch 1 including at least one battery pack 20 and the high voltage box 10 provided in this application.

[0105] In this application, by setting multiple battery packs 20 in each power supply branch 1, and while each battery pack 20 is connected in series, a fuse and / or a relay can also be connected in series to form a battery cluster, which can not only increase the voltage of the power supply branch 1, but also enhance the safety performance of the power supply branch 1.

[0106] In some embodiments, such as Figure 10 As shown, the energy storage system includes a second switching device K2 and N power supply branches 1, where N is a positive integer greater than or equal to 2, i.e., N is a natural number greater than 1; among them, the N power supply branches 1 are connected in parallel and then connected to the target device through a third switching device.

[0107] In this application, the second switching device K2 can be a disconnecting switch, and the target device can be an energy storage converter. The PCS+ and PCS- interfaces of the second switching device K2 are electrically connected to the energy storage converter, respectively. By setting a disconnecting switch between the energy storage converter and the high-voltage box 10, the main circuit of the energy storage system can be disconnected by the second switching device K2 when the high-voltage box 10 cannot be disconnected, thereby further ensuring the safety performance of the energy storage system.

[0108] Furthermore, in some embodiments, the fourth breaking current of the second switching device K2 is greater than N times the third breaking current of the first fuse FU+.

[0109] Specifically, this application can also solve the protection blind zone problem of the high-voltage box 10 by using the second switching device K2. By setting the fourth breaking current of the second switching device K2 to be greater than N times the third breaking current of the first fuse FU+, the second switching device K2 can be used to break the fault when the fault current of the power supply branch 1 is less than or equal to the minimum breaking current of the first fuse FU+; and the first fuse FU+ can be used to break the fault when the fault current of the power supply branch 1 is greater than the minimum breaking current of the first fuse FU+. This can avoid the occurrence of a protection blind zone when the protection devices in the high-voltage box 10 are used to protect the energy storage system.

[0110] In this embodiment, the breaking capacity of the second switching device K2 needs to be decomposed to the power supply branch 1 layer. If there are N power supply branches 1 in the energy storage system, then the current after N times the maximum breaking current of the second switching device K2, i.e., the third current, needs to be greater than the minimum breaking current of the first fuse FU+. Thus, when the fault current of the power supply branch 1 is less than or equal to the minimum breaking current of the first fuse FU+, the second switching device K2 can be used for breaking; when the fault current of the power supply branch 1 is greater than the minimum breaking current of the first fuse FU+, the first fuse FU+ can be used for breaking. This avoids the occurrence of protection blind spots when using the protection devices in the high-voltage box 10 to protect the energy storage system.

[0111] In some embodiments, such as Figure 10 As shown, the battery pack 20 includes a third fuse FU and at least one battery cell. The minimum breaking current of the third fuse FU is greater than or equal to the minimum breaking current of the first fuse FU+. The third fuse FU and at least one battery cell are connected in series and electrically connected to one end of the battery pack 20 and the other end of the battery pack 20, respectively. Alternatively, the third fuse FU and the battery cell are connected in series one-to-one and electrically connected to one end of the battery pack 20 and the other end of the battery pack 20, respectively, to achieve parallel connection. This allows the third fuse FU to quickly and effectively interrupt short circuits in the battery pack 20. The circuit containing battery pack 20 is disconnected in a timely manner to ensure the safety of battery pack 20. At the same time, the minimum breaking current of the third fuse FU can be greater than or equal to the minimum breaking current of the first fuse FU+, thereby avoiding the third fuse FU blowing before the first fuse FU+FU1. This reduces the number of times the third fuse FU needs to be replaced when replacing the fuses in the power supply branch 1, and thus reduces the number of times battery pack 20 needs to be disassembled and reassembled, greatly improving the maintenance efficiency of the energy storage system and reducing the maintenance cost of the energy storage system.

[0112] Furthermore, in some embodiments, the fusing speed of the first fuse FU+ is greater than the fusing speed of the third fuse FU.

[0113] In this implementation, the melting speed of the first fuse FU+ is greater than that of the third fuse FU. When both the first fuse FU+ and the third fuse FU meet the conditions for breaking, the first fuse FU+ will melt first, thereby avoiding increasing the number of times the battery pack 20 needs to be disassembled and reassembled.

[0114] In some embodiments, the target device is an energy storage converter; the energy storage converter can control the charging and discharging process of the power supply branch 1 and perform AC-DC conversion, and can also directly supply power to AC loads in the absence of a power grid.

[0115] It is understood that the high-voltage box and energy storage system provided in the above embodiments are merely examples. The description of the high-voltage box and energy storage system in this application is to more clearly illustrate the technical solutions of the embodiments of this application, and does not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of high-voltage boxes and energy storage systems and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems. Detailed descriptions are provided below.

[0116] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. The protection method for the energy storage system is described in detail below. Furthermore, the protection method for the energy storage system provided in this application can be executed by a battery management system.

[0117] Please see Figure 11 , Figure 11 This is a flowchart illustrating the protection method for an energy storage system provided in an embodiment of this application. Figure 11 As shown, this application also provides a protection method for an energy storage system, the method including steps S110 and S120.

[0118] S110. If the ratio between the fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold, the first switching device is disconnected to cut off the power supply branch.

[0119] S120. If the ratio between the detected fault current and the rated current is greater than the first threshold, the first fuse blows to cut off the power supply branch.

[0120] In this application, the energy storage system includes at least one power supply branch, which includes at least one battery pack and a high-voltage box. The high-voltage box includes a first switching device and a first fuse. The first fuse FU+ can be a conventional passive fuse or a Pyro fuse, i.e., a smart fuse. The first breaking capacity can be understood as the minimum breaking capacity of the first fuse FU+. The first switching device K1 can be at least one of a circuit breaker QF, a disconnector, or a fusion switch QF1. At the same time, at least one of the circuit breaker QF, the disconnector, and the fusion switch QF1 can be equipped with a tripping device. The first breaking current can be understood as the maximum breaking current of the first switching device K1.

[0121] Specifically, this application sets the minimum breaking capacity of the first fuse FU+ to be less than or equal to a preset first threshold, while the first threshold is less than or equal to the ratio between the preset current and the rated current of the first fuse FU+, and the first breaking capacity of the first fuse FU+ is less than or equal to the first threshold. Therefore, when the ratio between the fault current of the power supply branch and the rated current of the first fuse is detected to be less than or equal to the preset first threshold, it can be determined that the fault current of the energy storage system is less than or equal to the preset current. Thus, the first switching device K1 is used for protection. Conversely, when the ratio between the detected fault current and the rated current is greater than the first threshold, it can be determined that the fault current is greater than the preset current, and the first fuse FU+ is used for protection. This achieves global fault protection for the energy storage system, avoiding protection blind spots in the protection devices of the high-voltage box 10 and improving the safety performance of the energy storage system. The preset current can be understood as the second current mentioned in this application.

[0122] In some embodiments, if the ratio between the detected fault current and the rated current is greater than or equal to a first threshold, the first fuse blows to cut off the power supply branch, including: if the ratio between the detected fault current and the rated current is greater than the first threshold and the fault current is less than or equal to a preset current, the first switching device is disconnected to cut off the power supply branch; if the fault current is greater than the preset current, the first fuse blows to cut off the power supply branch.

[0123] In this application, when the ratio between the fault current and the rated current is detected to be greater than or equal to the first threshold, it is also necessary to determine whether the fault current is less than or equal to the preset current. If it is less than or equal to the preset current, the first switching device can be used to cut off the power supply branch. If it is greater than the preset current, in order to avoid the first switching device being unable to cut off the power supply branch, the first fuse needs to blow to cut off the power supply branch.

[0124] In some embodiments, if the ratio between the detected fault current and the rated current is greater than a first threshold, and the fault current is less than or equal to a preset current, disconnecting the first switching device to cut off the power supply branch includes: if the ratio between the detected fault current and the rated current is greater than a first threshold, and the fault current is less than or equal to a preset current, sending a first disconnection command to the first switching device; after a preset first time, disconnecting the first switching device based on the first disconnection command to cut off the power supply branch; the arc-precession time of the first fuse is greater than the first time.

[0125] In this application, when the ratio between the detected fault current and the rated current is greater than a first threshold and the fault current is less than or equal to a preset current, the battery management system can send a first disconnect command to the first switching device. Since there is a certain delay time between the battery management system detecting the fault signal and issuing the command and the trip unit receiving the signal and starting to execute, this application can disconnect the switching device based on the first disconnect command to cut off the power supply branch after a preset first time.

[0126] Meanwhile, since the first fuse may also blow when the ratio between the fault current of the power supply branch and the rated current of the first fuse is less than the preset first threshold and the fault current is less than or equal to the preset current, in order to prevent the first fuse from blowing before the first switching device, the arc-precession time of the first fuse needs to be set to be greater than the first time.

[0127] In some embodiments, if the first switching device includes a circuit breaker or a disconnecting switch; if the ratio between the detected fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold, disconnecting the first switching device to cut off the power supply branch includes: if the detected ratio between the fault current and the rated current is less than or equal to the first threshold, sending a second disconnection command to the circuit breaker or disconnecting switch; and after a preset second time, disconnecting the circuit breaker or disconnecting switch based on the second disconnection command to cut off the power supply branch.

[0128] In this application, the second disconnection command can be understood as a command sent by the battery management system to the tripping device installed in the circuit breaker or disconnector. There is a certain delay in the battery management system sending the second disconnection command to the tripping device installed in the circuit breaker or disconnector. Therefore, after a preset second time, the circuit breaker or disconnector can be disconnected based on the second disconnection command to cut off the power supply branch. The first and second times can be equal or unequal, and can be selected according to the actual application; this application does not impose specific limitations.

[0129] In some embodiments, if the first switching device includes a fusion switch; if the ratio between the detected fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold, disconnecting the first switching device to cut off the power supply branch includes: if the detected ratio between the fault current and the rated current is less than the first threshold, sending a third disconnection command to the fusion switch; and disconnecting the fusion switch based on the third disconnection command to cut off the power supply branch.

[0130] In this application, if the ratio between the fault current of the power supply branch and the rated current of the first fuse is less than a preset first threshold, it can be determined that the fault current of the energy storage system is less than or equal to the preset current. Then, a fusion switch is used for protection. When the ratio between the fault current and the rated current is greater than the first threshold, it can be determined that the fault current is greater than the preset current. Then, the first fuse FU+ is used for protection. This can achieve global fault protection for the energy storage system, avoid the protection blind zone of the protection devices in the high-voltage box, and improve the safety performance of the energy storage system.

[0131] In some embodiments, the fusion switch is provided with a motor tripping device and a shunt tripping device; disconnecting the fusion switch based on a third disconnection command to disconnect the power supply branch includes: controlling the motor tripping device to trip based on the third disconnection command to disconnect the power supply branch; if the power supply branch is detected to be not disconnected, sending a fourth disconnection command to the fusion switch; and controlling the shunt tripping device to trip based on the fourth disconnection command to disconnect the power supply branch.

[0132] In some embodiments, the fusion switch is provided with a shunt trip device and a shunt trip device. Disconnecting the fusion switch based on a third disconnection command to disconnect the power supply branch includes: controlling the shunt trip device to trip based on the third disconnection command to disconnect the power supply branch; if the power supply branch is detected to be not disconnected, sending a fifth disconnection command to the fusion switch; and controlling the motor trip device to trip based on the fifth disconnection command to disconnect the power supply branch.

[0133] In this application, the fusion switch can be equipped with both a motor tripping device and a shunt tripping device. Therefore, when the fusion switch is used to cut off the power supply branch, either the motor tripping device or the shunt tripping device can be used to cut off the power supply branch. The third, fourth, and fifth cut-off commands can be understood as commands sent to either the motor tripping device or the shunt tripping device.

[0134] Specifically, in the process of using a fusion switch to cut off the branch, this application can control the motor tripping device to trip based on the third tripping command to cut off the power supply branch, and when the motor tripping device trips but does not cut off the power supply branch, a shunt tripping device is used to cut off the power supply branch.

[0135] Meanwhile, in the process of cutting off the branch using the fusion switch, this application can also control the shunt trip device to trip to cut off the power supply branch using the third cutting-off command, and when the shunt trip device trips but does not cut off the power supply branch, the motor trip device is used to cut off the power supply branch.

[0136] In some embodiments, the protection method for the energy storage system further includes: if a power-on command for the power supply branch is received, sending a pre-charge command to the fusion switch; based on the pre-charge command, controlling the pre-charge contacts of the fusion switch to close to pre-charge the power supply branch; after a preset third time, sending a main charge command to the fusion switch; based on the main charge command, controlling the main charge contacts of the fusion switch to close and controlling the pre-charge contacts to open to power the power supply branch.

[0137] In this application, the fusion switch can also integrate the main negative relay and the pre-charge relay of the pre-charge circuit in the high-voltage box. When it receives the power-on command of the power supply branch, it can send a pre-charge command to the fusion switch to control the pre-charge contact of the fusion switch to close to pre-charge the power supply branch. After a third time, it sends a main charge command to the fusion switch to control the main charge contact of the fusion switch to close. After the main charge contact of the fusion switch closes, it controls the pre-charge contact to open to complete the power supply branch.

[0138] In some embodiments, the first switching device includes a second fuse; the protection method for the energy storage system further includes: if the ratio between the detected fault current and the rated current is less than or equal to a first threshold, the second fuse blows to cut off the power supply branch; if the ratio between the detected fault current and the rated current is greater than the first threshold, the first fuse blows to cut off the power supply branch.

[0139] In this application, the first fuse can be a conventional passive fuse, and the second fuse can be a Pyro fuse, thereby addressing the risk of insufficient protection against small short-circuit currents. The Pyro fuse, also known as a smart fuse, is an integrated active and passive device. When a fault current of any magnitude occurs, the battery management system detects the fault current signal and sends an excitation signal to the Pyro fuse. Upon receiving the external excitation signal, the Pyro fuse activates the igniter, cutting off the internal connection circuit, thus achieving rapid interruption of the circuit current.

[0140] Specifically, when the ratio between the detected fault current and the rated current is less than or equal to the first threshold, it can be determined that the fault current is less than or equal to the preset current, and the second fuse will blow to cut off the power supply branch; when the ratio between the detected fault current and the rated current is greater than the first threshold, it can be determined that the fault current is greater than the preset current, and the first fuse will blow to cut off the power supply branch. This can achieve global fault protection for the energy storage system, avoid the existence of protection blind spots in the protection devices in the high-voltage box, and improve the safety performance of the energy storage system.

[0141] It should be noted that the first fuse and the second fuse mentioned in this application can both be smart fuses, one of which can be a smart fuse and the other a traditional passive fuse, or both of which can be traditional passive fuses. The first fuse and the second fuse can be selected according to the actual application, and this application does not make any specific restrictions.

[0142] In some embodiments, the protection method for the energy storage system further includes: if the ratio between the fault current detected by the second fuse and the rated current is less than or equal to a first threshold, the second fuse blows to cut off the power supply branch.

[0143] In this application, the second fuse can also perform internal self-testing of fault current and send an excitation signal to trigger it, so as to form an integrated active and passive protection scheme to ensure the safety and reliability of the energy storage system. Then, when the ratio between the fault current detected by the second fuse and the rated current is less than or equal to the first threshold, the second fuse can be used to blow to cut off the power supply branch.

[0144] In some embodiments, the energy storage system further includes a second switching device and N power supply branches, where N is a natural number greater than 1. The N power supply branches are connected in parallel and then connected to the target device through the second switching device. The protection method of the energy storage system further includes: if the ratio between the detected fault current and the rated current is less than or equal to a first threshold, disconnecting the second switching device to cut off the power supply branches.

[0145] In this application, the second switching device can be a disconnecting switch at the junction of the energy storage system. The disconnecting switch can be equipped with a tripping device to solve the problem of protection blind zone of the high-voltage box. Thus, when the ratio between the detected fault current and the rated current is less than or equal to the first threshold, the second switching device can be used to disconnect; when the ratio between the detected fault current and the rated current is greater than the first threshold, the first fuse is used to disconnect. This can avoid the occurrence of protection blind zone when the protection device in the high-voltage box is used to protect the energy storage system.

[0146] The energy storage system protection method provided in this application disconnects the first switching device to cut off the power supply branch when the ratio between the detected fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold; and blows the first fuse to cut off the power supply branch when the detected fault current is greater than the first threshold. This method can achieve global fault protection for the energy storage system, avoid the existence of protection blind spots in the protection devices in the high-voltage box, and improve the safety performance of the energy storage system.

[0147] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A protection method for an energy storage system, characterized in that, The energy storage system includes at least one power supply branch, the power supply branch includes at least one battery pack and a high-voltage box, the high-voltage box includes a first switching device and a first fuse, and the method includes: If the ratio between the fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold, the first switching device is disconnected to cut off the power supply branch. If the ratio between the detected fault current and the rated current is greater than the first threshold, the first fuse blows to cut off the power supply branch.

2. The protection method for an energy storage system according to claim 1, characterized in that, The step of blowing the first fuse to disconnect the power supply branch if the ratio between the detected fault current and the rated current is greater than the first threshold includes: If the ratio between the fault current and the rated current is detected to be greater than the first threshold, and the fault current is less than or equal to the preset current, the first switching device is disconnected to cut off the power supply branch. If the fault current is greater than the preset current, the first fuse blows to cut off the power supply branch.

3. The protection method for an energy storage system according to claim 2, characterized in that, If the ratio between the detected fault current and the rated current is greater than the first threshold, and the fault current is less than or equal to a preset current, disconnecting the first switching device to cut off the power supply branch includes: If the ratio between the fault current and the rated current is detected to be greater than the first threshold, and the fault current is less than or equal to the preset current, a first disconnection command is sent to the first switching device. After a preset first time, the first switching device is disconnected based on the first cut-off command to cut off the power supply branch; the arc-pre-fuse time of the first fuse is greater than the first time.

4. The protection method for an energy storage system according to any one of claims 1-3, characterized in that, The first switching device includes a circuit breaker or a disconnector; The step of disconnecting the first switching device to cut off the power supply branch if the ratio between the fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold includes: If the ratio between the detected fault current and the rated current is less than or equal to the first threshold, a second disconnection command is sent to the circuit breaker or the disconnecting switch. After a preset second time, the circuit breaker or the disconnecting switch is disconnected based on the second disconnection command to cut off the power supply branch.

5. The protection method for an energy storage system according to any one of claims 1-3, characterized in that, The first switching device includes a fusion switch; The step of disconnecting the first switching device to cut off the power supply branch if the ratio between the fault current of the power supply branch and the rated current of the first fuse is less than or equal to a preset first threshold includes: If the ratio between the detected fault current and the rated current is less than or equal to the first threshold, a third disconnection command is sent to the fusion switch. The fusion switch is disconnected based on the third disconnection command to cut off the power supply branch.

6. The protection method for an energy storage system according to claim 5, characterized in that, The fusion switch is equipped with a motor tripping device and a shunt tripping device; Disconnecting the fusion switch based on the third disconnection command to cut off the power supply branch includes: Based on the third cut-off command, the motor tripping device is controlled to trip, thereby cutting off the power supply branch; If the power supply branch is detected to be uninterrupted, a fourth disconnection command is sent to the fusion switch; Based on the fourth cut-off command, the shunt trip device is controlled to trip, thereby cutting off the power supply branch.

7. The protection method for an energy storage system according to claim 5, characterized in that, The fusion switch is equipped with a motor tripping device and a shunt tripping device; Disconnecting the fusion switch based on the third disconnection command to cut off the power supply branch includes: Based on the third cut-off command, the shunt trip device is controlled to trip, thereby cutting off the power supply branch; If the power supply branch is detected to be uninterrupted, a fifth disconnection command is sent to the fusion switch; Based on the fifth cut-off command, the motor tripping device is controlled to trip, thereby cutting off the power supply branch.

8. The protection method for an energy storage system according to claim 5, characterized in that, The method further includes: If a power-on command is received from the power supply branch, a pre-charge command is sent to the fusion switch; Based on the pre-charge command, the pre-charge contacts of the fusion switch are controlled to close, so as to pre-charge the power supply branch; After a preset third time interval, a main charging command is sent to the fusion switch; Based on the main charging command, the main charging contacts of the fusion switch are closed, and the pre-charging contacts are opened to power the power supply branch.

9. The protection method for an energy storage system according to any one of claims 1-3, characterized in that, The first switching device includes a second fuse; the method includes: If the ratio between the fault current and the rated current is less than or equal to the first threshold, the second fuse blows to cut off the power supply branch. If the ratio between the detected fault current and the rated current is greater than or equal to the first threshold, the first fuse blows to cut off the power supply branch.

10. The protection method for an energy storage system according to claim 9, characterized in that, The method further includes: If the second fuse detects that the ratio between the fault current and the rated current is less than or equal to the first threshold, the second fuse blows to cut off the power supply branch.

11. The protection method for an energy storage system according to any one of claims 1-3, characterized in that, The energy storage system includes a second switching device and N power supply branches, where N is a natural number greater than 1. The N power supply branches are connected in parallel and then connected to the target device through the second switching device. The method further includes: If the ratio between the fault current and the rated current is detected to be less than or equal to the first threshold, the second switching device is disconnected to cut off the power supply branch.

12. An energy storage system, characterized in that, It includes at least one power supply branch, said power supply branch including: At least one battery pack; A high-voltage box includes a first fuse and a first switching device, wherein the first switching device is provided with a first terminal and a second terminal; The interface group includes the first interface, the second interface, the third interface, and the fourth interface; Wherein, the first end is electrically connected to one end of the first fuse, the other end of the first fuse is electrically connected to one end of the first interface, the second end is electrically connected to one end of the third interface, and one end of the second interface is electrically connected to one end of the fourth interface; or, the first end is electrically connected to one end of the first interface, the second end is electrically connected to one end of the third interface, one end of the first fuse is electrically connected to one end of the second interface, and the other end of the first fuse is electrically connected to one end of the fourth interface; The other ends of the first interface and the second interface are electrically connected to the two ends of the battery pack, respectively; the other ends of the third interface and the fourth interface are electrically connected to the first bus and the second bus of the energy storage system, respectively. The energy storage system is protected by the energy storage system protection method described in any one of claims 1-11.

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