Energy storage system and energy storage system protection method

Abstract

The application discloses an energy storage system and an energy storage system protection method. The energy storage system comprises a battery-level protection device, a direct-current protection device, a cluster-level protection device, a cabin-level protection device, a system-level protection device and a controller. The controller is configured to determine a target protection device from the battery-level protection device, the direct-current protection device, the cluster-level protection device, the cabin-level protection device and the system-level protection device according to the operating state of the energy storage system, and control the target protection device to perform a protection operation. Different protection devices are arranged at the battery module, the direct-current side of the battery cluster, the alternating-current side of the battery cluster, the alternating-current side of the battery cabin and the alternating-current side of the system of the energy storage system, so that the protection operation can be performed in a targeted manner when a fault occurs in the energy storage system, the energy storage system can be protected in a coordinated manner, the protection blind area caused by independent protection actions between the direct-current side and the alternating-current side of the energy storage system is reduced, and the safety and reliability of the energy storage system are improved.

Description

Technical Field

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

[0002] With the development of energy storage technology, the electrical safety protection of energy storage systems has received widespread attention. The safety protection of energy storage systems in related technologies typically involves separate protection operations on the AC and DC sides of the energy storage system. For example, an independent protection relay is configured on the AC side, while protection operations on the DC side are performed through the internal protection functions of the battery management system or the energy storage converter.

[0003] However, the current safety protection methods for energy storage systems are not very effective. How to improve the protection effect of energy storage systems, and thus improve their safety and reliability, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This application provides an energy storage system and an energy storage system protection method, which can provide comprehensive protection for the energy storage system from multiple levels, thereby improving the safety and reliability of the energy storage system.

[0005] To achieve the above objectives, according to a first aspect of this application, an energy storage system is provided, comprising: multiple battery compartments, each battery compartment including at least one battery cluster, each battery cluster including a power conversion module and a battery module, the DC terminal of the power conversion module being connected to the battery module, and the AC terminal of the power conversion module being connected in series with an AC bus; the energy storage system further includes: battery-level protection devices, DC protection devices, cluster-level protection devices, compartment-level protection devices, system-level protection devices, and a controller; the battery-level protection devices are disposed within the battery modules; the DC protection devices are disposed within the power conversion modules. The module's DC terminal is located between the battery module; the cluster-level protection device is located between the battery cluster's AC terminal and the AC bus; the compartment-level protection device is located between adjacent battery compartments or between the battery compartment and the AC bus; the system-level protection device is located between the energy storage system and the AC bus; the controller is configured to: determine a target protection device among the battery-level protection device, the DC protection device, the cluster-level protection device, the compartment-level protection device, and the system-level protection device according to the operating status of the energy storage system, and control the target protection device to perform protection operations.

[0006] Optionally, the protection levels of the battery-level protection device, the DC protection device, the cluster-level protection device, the cabin-level protection device, and the system-level protection device increase sequentially. The controller is further configured to: in response to the failure of the protection operation of the target protection device, control the next-level protection device of the target protection device to perform a protection operation.

[0007] Optionally, the energy storage system includes a bus connection terminal and a neutral point connection terminal. The system-level protection device includes: a phase line protection unit connected to the bus connection terminal and a neutral point protection unit connected to the neutral point connection terminal; wherein, the phase line protection unit includes: a first AC circuit breaker and a first disconnecting switch connected in series, and a plurality of first grounding switches disposed on both sides of the first AC circuit breaker and the first disconnecting switch; the neutral point protection unit includes: a second disconnecting switch and a plurality of second grounding switches disposed on both sides of the second disconnecting switch.

[0008] Optionally, the compartment-level protection device includes: a third disconnect switch and a third grounding switch disposed on the side of the third disconnect switch near the battery compartment; or, a third AC circuit breaker and a third disconnect switch connected in series, and a third grounding switch disposed on the side of the third disconnect switch near the battery compartment.

[0009] Optionally, the cabin-level protection device is encapsulated in a first housing, which is connected to a grounding terminal; the battery compartment is encapsulated in a second housing, which is connected to the midpoint of the cascaded potential within the battery compartment; the cabin-level protection device further includes: a housing grounding switch, the first end of which is insulated through the first housing and connected to the second housing of the battery compartment, and the second end of which is connected to the first housing.

[0010] Optionally, the battery cluster includes a first AC connection terminal and a second AC connection terminal; the cluster-level protection device includes: a bypass unit connected between the first AC connection terminal and the second AC connection terminal, and a connection unit connected between the battery cluster and the AC bus, wherein the on / off states of the bypass unit and the connection unit are opposite; wherein the bypass unit includes a bypass switch; the connection unit includes: a fourth disconnect switch and a fourth AC contactor connected in series; or, a fourth disconnect switch, a fourth AC circuit breaker, and a fourth AC contactor connected in series.

[0011] Optionally, the DC protection device includes: a first DC contactor and a first fuse connected in series; or, a first DC circuit breaker, a first DC contactor, and a first fuse connected in series.

[0012] Optionally, the battery module includes a battery assembly, and the battery-level protection device includes a second fuse connected in series with the battery assembly.

[0013] Optionally, the controller includes: a battery controller, a power conversion controller, and a relay protection controller connected in communication; the battery-level protection device and the DC protection device are both connected to the battery controller, the cluster-level protection device is connected to the power conversion controller; the cabin-level protection device and the system-level protection device are connected to the relay protection controller.

[0014] According to a second aspect of this application, a protection method for an energy storage system is provided. The energy storage system includes: multiple battery compartments, each battery compartment including at least one battery cluster, each battery cluster including a power conversion module and a battery module, the DC terminal of the power conversion module being connected to the battery module, and the AC terminal of the power conversion module being connected in series with an AC bus; the energy storage system further includes: battery-level protection devices, DC protection devices, cluster-level protection devices, compartment-level protection devices, and system-level protection devices; the battery-level protection devices are disposed within the battery modules; the DC protection devices are disposed between the DC terminal of the power conversion module and the battery module; the cluster-level protection devices are disposed between the AC terminal of the battery cluster and the AC bus; the compartment-level protection devices are disposed between adjacent battery compartments or between the battery compartment and the AC bus; the system-level protection devices are disposed between the energy storage system and the AC bus; the method includes: determining a target protection device among the battery-level protection devices, the DC protection devices, the cluster-level protection devices, the compartment-level protection devices, and the system-level protection devices according to the operating state of the energy storage system, and controlling the target protection device to perform a protection operation.

[0015] Optionally, the protection levels of the battery-level protection device, the DC protection device, the cluster-level protection device, the cabin-level protection device, and the system-level protection device increase sequentially. The method further includes: in response to the failure of the protection operation of the target protection device, controlling the next-level protection device of the target protection device to perform a protection operation.

[0016] Optionally, the method further includes: acquiring operating data of the energy storage system, the operating data including at least one of current, voltage, temperature or pressure; and determining the operating status of the energy storage system based on the operating data.

[0017] Optionally, the method further includes: in response to a shutdown and maintenance command, controlling the energy storage system to stop power conversion; controlling the protection devices of each protection level to disconnect in sequence from the AC side to the DC side; controlling the energy storage elements in the energy storage system to discharge, and controlling the grounding switch to close after discharge verification to enter the maintenance state.

[0018] Optionally, the method further includes: controlling the grounding switch in the closed state to open in response to a power-on restoration command; and controlling the protection devices of multiple protection levels to close in sequence from the DC side to the AC side.

[0019] In summary, the energy storage system of this application includes: multiple battery compartments, each battery compartment including at least one battery cluster, the battery cluster including a power conversion module and a battery module, the DC terminal of the power conversion module being connected to the battery module, and the AC terminal of the power conversion module being connected in series with the AC bus; the energy storage system also includes: battery-level protection devices, DC protection devices, cluster-level protection devices, compartment-level protection devices, system-level protection devices, and a controller; the battery-level protection devices are disposed within the battery modules; the DC protection devices are disposed between the DC terminal of the power conversion module and the battery module; the cluster-level protection devices are disposed between the AC terminal of the battery cluster and the AC bus; the compartment-level protection devices are disposed between adjacent battery compartments or between a battery compartment and the AC bus; the system-level protection devices are disposed between the energy storage system and the AC bus; the controller is configured to: determine a target protection device among the battery-level protection devices, DC protection devices, cluster-level protection devices, compartment-level protection devices, and system-level protection devices according to the operating status of the energy storage system, and control the target protection device to perform protection operations.

[0020] The above technical solution sets up different protection devices on the battery modules, DC side of the battery clusters, AC side of the battery clusters, AC side of the battery compartments, and AC side of the system in the energy storage system. The corresponding protection level can be selected according to the location and scope of the fault, and targeted protection operations can be performed when the energy storage system fails. The setting of multi-level protection devices can also provide coordinated protection for the energy storage system. For example, if a certain protection device cannot clear the fault, backup protection can be achieved through other protection devices. This not only achieves comprehensive protection for the energy storage system, but also reduces the protection blind spots caused by independent protection actions between the DC and AC sides of the energy storage system, thereby improving the safety and reliability of the energy storage system. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples of this application; those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0022] Figure 1 Schematic diagrams of the energy storage system provided for some embodiments of this application; Figure 2 Structural schematic diagrams of the battery compartment provided for some embodiments of this application; Figure 3 Structural schematic diagrams of the battery compartment provided for other embodiments of this application; Figure 4 for Figure 3 A magnified view of a section at point A in the middle; Figure 5 Schematic diagram of controller connection provided for other embodiments of this application; Figure 6 A flowchart illustrating an energy storage system protection method provided in some embodiments of this application; Figure 7 A flowchart illustrating another energy storage system protection method provided for some embodiments of this application; Figure 8 A flowchart illustrating the shutdown and maintenance process of an energy storage system provided for some embodiments of this application; Figure 9 This is a schematic diagram illustrating the process of restoring power to an energy storage system according to some embodiments of this application.

[0023] Explanation of icon numbers: 10. Battery compartment; 20. Battery cluster; 30. Power conversion module; 40. Battery module; 100. Battery-level protection device; 200. DC protection device; 310. Bypass unit; 320. Connection unit; 400. Cabin-level protection device; 510. Phase line protection unit; 520. Neutral point protection unit; 610. Battery controller; 620. Power conversion controller; 630. Relay protection controller. Detailed Implementation

[0024] 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 a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0025] With the large-scale application of electrochemical energy storage power stations, especially lithium battery energy storage systems, in power systems, the electrical safety of energy storage systems has received widespread attention. The protection configuration of related energy storage systems is usually similar to that of power systems, with independent relay protection devices configured on the AC side of the energy storage system, while the DC side relies on the internal protection functions of the battery management system (BMS) and power conversion system (PCS).

[0026] However, in the protection methods of related technologies, the protection actions (such as current threshold and operating time) of AC-side relay protection and DC-side BMS are independent, lacking coordination. Improper coordination can easily create protection blind spots. Furthermore, although BMS can sensitively detect overvoltage, undervoltage, and overtemperature faults in the battery itself, its actuators (usually contactors) have limited breaking capacity and speed, making it difficult to quickly disconnect DC short-circuit faults reaching tens of kiloamperes. While DC circuit breakers possess strong breaking capacity, relying solely on their inverse-time current characteristics makes them insufficiently sensitive to small-current faults such as early internal short circuits in energy storage batteries.

[0027] In view of this, this application provides an energy storage system and an energy storage system protection method, which can provide comprehensive protection for the energy storage system from multiple levels, thereby improving the safety and reliability of the energy storage system.

[0028] In a first aspect, embodiments of this application provide an energy storage system.

[0029] Please see Figure 1 , Figure 1 The diagram illustrates the structure of an energy storage system provided for some embodiments of this application. For example... Figure 1 As shown, the energy storage system includes: multiple battery compartments 10, each battery compartment 10 including at least one battery cluster 20, the battery cluster 20 including a power conversion module 30 and a battery module 40, the DC terminal of the power conversion module 30 being connected to the battery module 40, and the AC terminal of the power conversion module 30 being connected in series with an AC bus; the energy storage system also includes: a battery-level protection device 100, a DC protection device 200, a cluster-level protection device, a compartment-level protection device 400, a system-level protection device, and a controller; the battery-level protection device 100 is disposed within the battery module 40; the DC protection device 200 is disposed within the battery module 40. The power conversion module 30 is located between the DC terminal and the battery module 40; the cluster-level protection device is located between the AC terminal of the battery cluster 20 and the AC bus; the compartment-level protection device 400 is located between adjacent battery compartments 10 or between the battery compartment 10 and the AC bus; the system-level protection device is located between the energy storage system and the AC bus; the controller is configured to: determine the target protection device among the battery-level protection device 100, DC protection device 200, cluster-level protection device, compartment-level protection device 400 and system-level protection device according to the operating status of the energy storage system, and control the target protection device to perform protection operation.

[0030] In energy storage systems, direct-grid connected energy storage systems connect a large number of battery compartments in series to achieve a certain grid voltage level, enabling direct grid connection without the need for a step-up transformer. This approach is highly efficient and cost-effective. This application uses a direct-grid connected energy storage system as an example to illustrate the protection system of this application embodiment. It is understood that this application embodiment does not limit the type of energy storage system; different types of energy storage systems can be determined according to application requirements. In some implementations, the energy storage system is a medium-voltage direct-grid connected energy storage system, corresponding to AC grids of 10kV, 35kV, etc. This application embodiment does not specifically limit this type.

[0031] The energy storage system is a direct-connected grid energy storage system. The AC bus of the AC grid includes three-phase power transmission lines: phase A, phase B, and phase C. The energy storage system comprises multiple energy storage branches, each corresponding to one phase of the AC bus of the AC grid, used to realize the power transmission of that phase. For example... Figure 1 As shown, the energy storage branch includes a battery compartment 10. When the energy storage branch includes multiple battery compartments 10, these compartments are connected in series. The battery compartment 10 can be a container, cabinet, or other enclosed or semi-enclosed structure capable of accommodating battery clusters 20. Each battery compartment 10 includes at least one battery cluster 20. Multiple battery clusters 20 within the same battery compartment 10 are connected in series to an AC bus to directly transmit electrical energy to the power grid via the AC bus.

[0032] Please see Figure 2 , Figure 2 This is a structural schematic diagram of the battery compartment provided for some embodiments of this application. For example... Figure 2 As shown, the first battery compartment 10 in the A-phase AC bus includes multiple battery clusters 20 connected in series. Each battery cluster 20 includes a battery module 40 and a power conversion module 30. The battery module 40 is used to store and release electrical energy. Exemplarily, the battery module 40 includes one or more battery packs, which may include one or more battery modules, each including multiple battery cells. The DC terminal of the power conversion module 30 is connected to the battery module 40 for transmitting DC power between the two modules. The AC terminal of the power conversion module 30 is connected in series to the AC bus, so that multiple power conversion modules 30 are cascaded on the AC side. Exemplarily, the power conversion module 30 includes an inverter circuit to achieve the conversion between AC and DC power.

[0033] The energy storage system in this embodiment of the application also includes a battery-level protection device 100, a DC protection device 200, a cluster-level protection device, a cabin-level protection device 400, and a system-level protection device. Different protection devices correspond to different protection levels of the energy storage system, and the protection range corresponding to different protection levels expands sequentially to form a multi-level protection architecture from the inside of the battery module 40 to the whole energy storage system.

[0034] like Figure 2 As shown, the battery-level protection device 100 is installed within the battery module 40. When an abnormality such as overcurrent or short circuit occurs in the battery pack or battery module within the battery module 40, the corresponding current path is cut off. The battery-level protection device 100, installed within the battery module 40, directly isolates the corresponding faulty branch when an abnormality occurs in a local branch within the battery module 40, preventing the entire battery cluster 20, the entire battery compartment 10, or the entire energy storage system from shutting down, thereby reducing the scope of the fault's impact.

[0035] A DC protection device 200 is disposed between the DC terminal of the power conversion module 30 and the battery module 40, and is used to control the DC connection between the battery module 40 and the power conversion module 30. Exemplarily, the DC protection device 200 can be connected to the positive terminal of the battery module 40, the negative terminal of the battery module 40, or both the positive and negative terminals of the battery module 40. When a short circuit, overcurrent, or other abnormality occurs at the DC terminal of the battery module 40 or the power conversion module 30, the DC protection device 200 disconnects the DC path between the battery module 40 and the power conversion module 30 to perform a protection operation. The DC protection device 200 can prevent the battery module 40 from continuing to transmit power to the power conversion module 30 by switching the DC path of the power conversion module 30 when the battery module 40 malfunctions.

[0036] Cluster-level protection devices are installed between the AC terminal of battery cluster 20 and the AC bus to achieve fault isolation and safety protection of the AC terminal of battery cluster 20. During normal operation of battery cluster 20, the cluster-level protection devices are normally activated, and the AC terminal of power conversion module 30 is connected to the AC bus. When a fault occurs in battery cluster 20 or power conversion module 30, the cluster-level protection devices can perform disconnection, bypass, or fault clearing operations, disconnecting the corresponding battery cluster 20 from the AC bus. This embodiment of the application can prevent the entire battery compartment 10 or the entire energy storage system from shutting down by controlling the corresponding cluster-level protection device when a fault occurs in a battery cluster 20.

[0037] The compartment-level protection device 400 is disposed between adjacent battery compartments 10 or between a battery compartment 10 and the AC bus. For multiple battery compartments 10 connected in series, the compartment-level protection device 400 can be disposed between two adjacent battery compartments 10. For a battery compartment 10 located at the end of an AC branch, the compartment-level protection device 400 can be disposed between that battery compartment 10 and the AC bus. The compartment-level protection device 400 is used to isolate the corresponding battery compartment 10 from the AC bus or adjacent battery compartments 10 when a battery compartment 10 fails or needs maintenance. The compartment-level protection device 400 can provide independent protection for a single battery compartment 10 or serve as a backup protection level above the cluster-level protection device.

[0038] The system-level protection device is located between the energy storage system and the AC bus. When a system-level fault occurs in the energy storage system, multiple battery compartments 10 malfunction simultaneously, or the entire energy storage system needs to be shut down for maintenance, the system-level protection device can perform protection operations to isolate the energy storage system from the AC bus.

[0039] The controller is connected to the battery-level protection device 100, DC protection device 200, cluster-level protection device, cabin-level protection device 400, and system-level protection device. It can determine the protection device that needs to perform protection operation as the target protection device in each level of protection device according to the operating status of the energy storage system, and control the target protection device to perform protection operation.

[0040] The operating status of an energy storage system includes normal operation, abnormal operation, shutdown, maintenance, and power-on recovery. Abnormal operation can be further categorized based on the location, type, and severity of the anomaly. Taking an anomaly in the energy storage system as an example, the controller determines the location and severity of the anomaly based on its state. Then, it identifies the corresponding protection device as the target protection device and controls it to perform protective operations. These operations include disconnection, fuse blowing, bypassing, and grounding.

[0041] In this embodiment, different protection devices are respectively set on the DC side of the battery module 40, the AC side of the battery cluster 20, the AC side of the battery compartment 10, and the AC side of the system in the energy storage system. The corresponding protection level can be selected according to the location of the fault and the scope of the fault impact, and the protection operation can be performed in a targeted manner when the energy storage system fails. The setting of multi-level protection devices can also provide coordinated protection for the energy storage system. For example, if a certain protection device cannot clear the fault, backup protection can be achieved through other protection devices. This not only achieves comprehensive protection for the energy storage system, but also reduces the protection blind spot caused by independent protection actions between the DC side and the AC side of the energy storage system, thereby improving the safety and reliability of the energy storage system.

[0042] In some embodiments, the protection levels of the battery-level protection device 100, DC protection device 200, cluster-level protection device, cabin-level protection device 400, and system-level protection device increase sequentially, and the controller is further configured to: in response to the failure of the protection operation of the target protection device, control the next-level protection device of the target protection device to perform a protection operation.

[0043] The protection level of the protection devices is determined based on the protection range, the interruptible fault current, the fault isolation area, and the corresponding outage range. The protection range of battery-level protection device 100 is the interior of battery module 40. The protection range of DC protection device 200 is the DC path between the entire battery module 40 and the power conversion module 30. The protection range of cluster-level protection device is a single battery cluster 20. The protection range of compartment-level protection device 400 is a battery compartment 10. The protection range of system-level protection devices can be the entire energy storage branch or the entire energy storage system.

[0044] Failure of the target protection device to perform protection operation includes: the target protection device failing to complete the state switch within the preset time; the feedback state of the target protection device after performing the protection operation being inconsistent with the target state; and the target protection device still detecting abnormalities in its operating state after performing the protection operation. For example, when the battery-level protection device 100 fails to isolate the faulty battery module within the battery module 40, the controller isolates the entire battery module 40 through the DC protection device 200; if the DC protection device 200 fails to clear the fault, the controller controls the cluster-level protection device to isolate the entire battery cluster 20 from the AC bus; if the cluster-level protection device fails to operate, the controller controls the compartment-level protection device 400 to perform the protection operation; if the compartment-level protection device 400 still fails to clear the fault, the controller controls the system-level protection device to perform the protection operation.

[0045] It should be noted that when the controller controls the upper-level protection device to perform protection operations, it does not restrict the state of the lower-level protection device; it simply cuts off other power supply paths to the fault by expanding the isolation range.

[0046] This application embodiment sets progressively higher protection levels and provides backup protection by setting an upper-level protection device. When the lower-level protection device cannot clear the fault, the upper-level protection device can expand the isolation range and clear the fault, which has a better fault tolerance rate and can improve the safety and reliability of the energy storage system.

[0047] In some embodiments, the energy storage system includes a bus connection terminal and a neutral point connection terminal. The system-level protection device includes a phase line protection unit 510 connected to the bus connection terminal and a neutral point protection unit 520 connected to the neutral point connection terminal. The phase line protection unit 510 includes a first AC circuit breaker and a first disconnecting switch connected in series, and a plurality of first grounding switches disposed on both sides of the first AC circuit breaker and the first disconnecting switch. The neutral point protection unit 520 includes a second disconnecting switch and a plurality of second grounding switches disposed on both sides of the second disconnecting switch.

[0048] The busbar connection terminal is the electrical port connecting the energy storage system to the corresponding phase line of the AC bus. The neutral point connection terminal is the common electrical connection terminal formed by connecting the ends of the multi-phase energy storage branches furthest from the AC bus. The neutral point connection terminal can be in a floating state or connected to the grounding terminal. The phase line protection unit 510 is connected between the busbar connection terminal and the energy storage branch, controlling the connection status between the energy storage system and the phase line side of the AC bus. The neutral point protection unit 520 is connected between the neutral point connection terminal and the neutral point bus position of the energy storage system, used to control the connection status of the neutral point side of the energy storage system.

[0049] like Figure 1 As shown, the phase line protection unit 510 includes: a first AC circuit breaker QFA and a first disconnecting switch QS1A connected in series, and a plurality of first grounding switches disposed on both sides of the first AC circuit breaker QFA and the first disconnecting switch QS1A; the plurality of first grounding switches are respectively the grounding switch ES1A between the first disconnecting switch QS1A and the energy storage branch, the grounding switch ES2A between the first disconnecting switch QS1A and the first AC circuit breaker QFA, and the grounding switch ES3A between the first AC circuit breaker QFA and the AC phase line connection terminal.

[0050] The first AC circuit breaker is used to interrupt the normal load current or fault current between the energy storage system and the AC bus. The first disconnecting switch is used to form a recognizable electrical isolation point after the first AC circuit breaker has opened. The first disconnecting switch is typically not used to directly interrupt large fault currents, but rather to perform isolation operations after the first AC circuit breaker has opened. The first grounding switch is used to connect to the grounding terminal to discharge through a grounding operation.

[0051] Please continue reading. Figure 1 The neutral point protection unit 520 includes a second disconnecting switch QS2A and a plurality of second grounding switches disposed on both sides of the second disconnecting switch QS2A; the second grounding switches are ES4A and ES5A on both sides of the second disconnecting switch QS2A. The second disconnecting switch is used to disconnect the neutral point connection path of the energy storage system, and the second grounding switches are used to connect to the grounding terminal to discharge through grounding operation.

[0052] For example, during a shutdown maintenance of the energy storage system, the first AC circuit breaker in the phase line protection unit 510 can be disconnected first, followed by the first disconnecting switch; then the second disconnecting switch in the neutral point protection unit 520 can be disconnected. After confirming no power is applied, the corresponding first and second grounding switches can be closed.

[0053] In this embodiment, system-level protection devices are installed at the bus connection end and the neutral point connection end of the energy storage system, respectively. This can isolate the energy storage system from both the phase line side and the neutral point side simultaneously, avoiding residual potential on the neutral point side after only disconnecting the phase line side, and improving the integrity of system-level fault isolation and maintenance grounding.

[0054] In some embodiments, please continue reading Figure 1 The phase line protection unit 510 also includes a current transformer TA1A, which is connected between the first disconnecting switch QS1A and the energy storage system. The neutral point protection unit 520 also includes a current transformer TA2A, which is connected between the second disconnecting switch QS2A and the energy storage system.

[0055] Current transformers are used to collect the current in the corresponding AC path so that the controller can monitor the operating status, such as overcurrent, short circuit, and grounding fault, based on the collected current.

[0056] In some embodiments, the compartment protection device 400 includes: a third disconnecting switch and a third grounding switch disposed on the side of the third disconnecting switch near the battery compartment 10. Alternatively, the compartment protection device 400 includes: a third AC circuit breaker and a third disconnecting switch connected in series, and a third grounding switch located on the side of the third disconnecting switch near the battery compartment 10.

[0057] Please continue reading. Figure 1 and Figure 2 Each side of the battery compartment 10 is equipped with a compartment-level protection device 400, which is used to control the on / off state between the battery compartment 10 and the AC bus, as well as between the battery compartment 10 and other energized parts. By controlling the disconnection of the compartment-level protection device 400 on at least one side of the battery compartment 10, the controller can isolate the battery compartment 10 from the corresponding AC phase line and other energized parts in the energy storage branch.

[0058] Taking the compartment-level protection device 400 between the first battery compartment 10 and the AC phase line as an example, the compartment-level protection device 400 includes a third disconnecting switch QSA0 and a third grounding switch ESA0 disposed on the side of the third disconnecting switch QSA0 near the battery compartment 10. Figure 2 As shown, in some implementations, the compartment protection device 400 includes a third AC circuit breaker QFA0 and a third disconnecting switch QSA0 connected in series, and a third grounding switch ESA0 disposed on the side of the third disconnecting switch QSA0 near the battery compartment 10.

[0059] The third AC circuit breaker is used to interrupt the load current or fault current of the battery compartment. The third disconnecting switch is used to form a maintenance isolation break, isolating the battery compartment 10 from adjacent battery compartments 10 or the AC bus. The third grounding switch closes when the third disconnecting switch is determined to be open, grounding the battery compartment 10. Taking normal shutdown as an example, first control the battery compartment 10 to stop power conversion and transmission, then open the third AC circuit breaker, then open the third disconnecting switch. After the power-off verification is completed and it is determined that the battery compartment 10 meets the power-off conditions, close the third grounding switch to connect the battery compartment 10 to the grounding terminal.

[0060] The compartment-level protection device 400 of this application embodiment is equipped with an isolating switch, a grounding switch and an optional circuit breaker for the battery compartment 10, which can realize fault current isolation, maintenance isolation and grounding protection at the battery compartment level.

[0061] In some embodiments, the compartment protection device 400 is encapsulated in a first housing, which is connected to a grounding terminal; the battery compartment 10 is encapsulated in a second housing, which is connected to the midpoint of the cascaded potential within the battery compartment 10. The compartment protection device 400 further includes: a housing grounding switch, the first end of which is insulated through the first housing and connected to the second housing of the battery compartment 10, and the second end of which is connected to the first housing.

[0062] The first housing is the switch compartment housing or switch cabinet housing that houses the compartment-level protection device 400. The first housing can be made of metal and reliably connected to the grounding terminal through a grounding conductor, so that the first housing is grounded during the shutdown and maintenance of the energy storage system, reducing the risk of electric shock caused by the first housing being energized.

[0063] The second housing is a metal enclosure that houses the battery compartment 10. The second housing is connected to the midpoint of the cascaded potential within the battery compartment 10. The midpoint of the cascaded potential refers to the intermediate potential node in the AC cascaded circuit formed by multiple series-connected battery clusters 20 within the battery compartment 10. Connecting the second housing to the midpoint of the cascaded potential ensures that the potential of the second housing is positioned in the middle of the cascaded potential distribution within the battery compartment 10, reducing the potential difference between the electrical components near the ends of the cascaded circuit within the battery compartment 10 and the second housing.

[0064] Please see Figure 3 , Figure 3 Schematic diagrams of the battery compartment provided for other embodiments of this application, such as Figure 3 As shown, the cabin-level protection device 400 also includes a housing grounding switch, a first terminal of which passes through a first housing and is electrically connected to a second housing, and a second terminal of which is electrically connected to the first housing. In some implementations, the first terminal of the housing grounding switch passes through the first housing via an insulating sleeve, thereby maintaining electrical insulation between the first terminal and the first housing as it passes through the first housing.

[0065] Since the first housing is connected to the grounding terminal, when the housing grounding switch is closed, the second housing can be connected to the grounding terminal in sequence through the housing grounding switch and the first housing, thereby reliably grounding the second housing.

[0066] Please see Figure 4 , Figure 4 for Figure 3 A magnified view of a portion of point A, as shown below. Figure 4As shown, the first end of the outer casing grounding switch ESSA1 passes through the first casing and is connected to the second casing, while the second end is connected to the first casing. The second casing is connected to the cascaded potential midpoint within the battery compartment 10 via switches S2A1 and S1A1.

[0067] During normal operation of the energy storage system, the casing grounding switch ESSA1 of the compartment protection device 400 is in the open state, maintaining electrical isolation between the first and second casings. At this time, the first casing maintains the ground potential, and the second casing is at the corresponding cascade potential midpoint. Since each battery compartment 10 in the medium-voltage direct-connected energy storage system may be located at different cascade potentials, the second casing can be set to floating ground during normal operation and maintain a preset potential at the corresponding cascade potential midpoint.

[0068] During the shutdown and maintenance of the energy storage system, first, control the energy storage system to shut down, control the power conversion module 30 to stop power conversion, and disconnect the electrical connection between the battery compartment 10 and the AC phase line, neutral point, or adjacent battery compartments 10. Subsequently, discharge the energy storage elements in the battery compartment 10, and after confirming that the battery compartment 10 meets the de-energized conditions, close the outer casing grounding switch ESSA1 and switches S2A1 and S1A1, so that the second casing of the battery compartment 10 is connected to the grounding terminal in sequence through the outer casing grounding switch and the first casing, releasing the charge on the second casing to the ground, and switching the second casing from the cascaded potential to the grounding potential.

[0069] The compartment-level protection device 400 in this application embodiment includes a housing grounding switch, which can control the grounding of the second housing of the battery compartment 10 according to the operating status of the energy storage system, while meeting the insulation requirements under the operating status of the energy storage system and the safety requirements under the maintenance status.

[0070] In some embodiments, the battery cluster 20 includes a first AC connection terminal and a second AC connection terminal. The cluster-level protection device includes a bypass unit 310 connected between the first and second AC connection terminals, and a connection unit 320 connected between the battery cluster 20 and the AC busbar, wherein the bypass unit 310 and the connection unit 320 have opposite on / off states. The bypass unit 310 includes a bypass switch. The connection unit 320 includes a fourth disconnect switch and a fourth AC contactor connected in series. Alternatively, the connection unit 320 includes a fourth disconnect switch, a fourth AC circuit breaker, and a fourth AC contactor connected in series.

[0071] The first and second AC connection terminals of the battery cluster 20 are the two AC connection terminals through which the battery cluster 20 connects to the energy storage branch. A bypass unit 310 is connected between the first and second AC connection terminals, and a connection unit 320 is used to control the connection state between the power conversion module 30 and the AC bus. The on / off states of the bypass unit 310 and the connection unit 320 are opposite; that is, under normal operating conditions, the connection unit 320 is on and the bypass unit 310 is off; under bypass conditions, the connection unit 320 is off and the bypass unit 310 is on.

[0072] For example, when the battery cluster 20 is operating normally, the connection unit 320 is in the on state, the bypass unit 310 is in the off state, and the AC current passes through the power conversion module. When the battery cluster 20 malfunctions or needs to be taken out of operation, the connection unit 320 is disconnected, and after confirming that the connection unit 320 is disconnected, the bypass unit 310 is closed, so that the AC current of the AC bus can bypass the battery cluster 20 through the bypass channel formed by the bypass unit 310.

[0073] The bypass unit 310 includes a bypass switch. The bypass switch can be a contactor or a circuit breaker. Figure 2 For example, the bypass switch corresponding to the first battery cluster in battery compartment A1 is S3A11.

[0074] Please continue reading. Figure 2 The connection unit 320 includes: a fourth disconnecting switch QSA11 and a fourth AC contactor KMA11 connected in series. Alternatively, the connection unit 320 includes: a fourth disconnecting switch QSA11, a fourth AC circuit breaker QFA11, and a fourth AC contactor KMA11 connected in series.

[0075] The fourth disconnecting switch QSA11 can form an electrical isolation break when the battery cluster 20 is shut down or under maintenance; the fourth AC contactor KMA11 can meet the frequent connection and disconnection of the power conversion module 30 during normal operation of the energy storage system. The fourth AC circuit breaker QFA11 is an optional protective component in the connection unit 320, used to cut off the fault current when an AC overcurrent, short circuit or ground fault occurs on the AC side of the battery cluster 20.

[0076] During normal operation of the energy storage system, connection unit 320 first closes the fourth disconnecting switch QSA11, then closes the fourth AC contactor KMA11. When connection unit 320 includes the fourth AC circuit breaker QFA11, the fourth AC circuit breaker QFA11 is closed after the fourth disconnecting switch QSA11 is closed, followed by the fourth AC contactor KMA11. When the energy storage system shuts down, the power conversion module 30 is first controlled to stop power conversion, then the fourth AC contactor KMA11 is disconnected; when connection unit 320 includes the fourth AC circuit breaker QFA11, the fourth AC circuit breaker QFA11 is disconnected, and finally the fourth disconnecting switch QSA11 is disconnected. During maintenance, after the fourth disconnecting switch QSA11 is open and the battery cluster 20 is confirmed to be disconnected, the power conversion module 30 and related AC circuits are tested and inspected.

[0077] The cluster-level protection device in this application includes a bypass unit 310 and a connection unit 320. When a single battery cluster 20 fails, the bypass unit 310 can isolate and bypass the battery cluster 20, while maintaining the electrical continuity of other battery clusters 20 in the same AC series branch, reducing the situation where a single cluster failure causes the entire energy storage branch to shut down.

[0078] In some embodiments, the DC protection device 200 includes a first DC contactor and a first fuse connected in series. Alternatively, it includes a first DC circuit breaker, a first DC contactor, and a first fuse connected in series.

[0079] The DC protection device 200 includes a first DC contactor KMDA11 and a first fuse FUA11 connected in series. In some implementations, such as... Figure 2 As shown, the DC protection device 200 includes: a first DC circuit breaker QFDA11, a first DC contactor KMDA11, and a first fuse FUA11 connected in series.

[0080] The first DC contactor controls the connection or disconnection of the DC path between the battery module 40 and the power conversion module 30. The first fuse blows when the DC current reaches a preset blowing condition to cut off the fault current; it can serve as backup protection in case of a severe short circuit or switch failure. The first fuse can be a passive fuse or an active fuse. A passive fuse blows based on the heat generated by the fault current; an active fuse actively cuts off the current path in response to a trigger signal from the battery management system. The first DC circuit breaker is an optional protective component, capable of disconnecting the connection in the event of a large DC fault; if the first fuse is an active fuse, the first DC circuit breaker can be omitted.

[0081] For example, when the battery module 40 malfunctions, the first DC contactor is controlled to disconnect; when the fault current is large or the first DC contactor cannot effectively cut off the current, the first DC circuit breaker is controlled to perform a protection operation; when the fault current further increases or the first DC circuit breaker fails to operate, the first fuse is controlled to blow.

[0082] The DC protection device 200 of this application embodiment connects a DC contactor, a DC circuit breaker, and a fuse in series. By utilizing the repeatable operation capability of the DC contactor, the fault current breaking capability of the DC circuit breaker, and the fast backup protection capability of the fuse, the speed and reliability of DC side protection are improved.

[0083] In some embodiments, the battery module 40 includes a battery module, and the battery-level protection device 100 includes a second fuse connected in series with the battery module.

[0084] Battery module 40 includes one or more battery modules. Each battery module may include multiple cells connected in series and / or parallel. Please continue reading. Figure 2 In the battery-level protection device 100, the second fuse is connected in series with one battery module or in series with a branch consisting of multiple battery modules. When an overcurrent or short circuit occurs in the battery module, the second fuse trips to isolate the battery module.

[0085] The second fuse can be either an active fuse or a passive fuse. When the second fuse is an active fuse, the battery management system can determine whether the battery module is in an abnormal state based on the battery module's voltage, temperature, current, insulation status, or other status parameters, and send a trigger signal to the second fuse to blow when it is determined that the battery module needs to be isolated. When the second fuse is a passive fuse, it blows due to thermal effect when the fault current meets the blowing conditions.

[0086] The battery-level protection device 100 in this application embodiment includes a second fuse connected in series with the battery module. When a single battery module malfunctions, it can preferentially cut off the local fault, avoiding direct isolation of the entire battery module 40 or the entire battery cluster 20, thereby reducing the scope of the fault and improving the stability of the energy storage system operation.

[0087] In some embodiments, please refer to Figure 5 , Figure 5 This is a schematic diagram of controller connection provided for other embodiments of this application. For example... Figure 5 As shown, the controller includes: a battery controller 610, a power conversion controller 620, and a relay protection controller 630, which are connected in communication; a battery-level protection device 100 and a DC protection device 200 are both connected to the battery controller, a cluster-level protection device is connected to the power conversion controller; a cabin-level protection device 400 and a system-level protection device are connected to the relay protection controller.

[0088] The battery controller 610 is the controller corresponding to the battery module 40, such as a battery management system (BMS). Based on parameters such as current, voltage, temperature, and pressure of the battery module 40, the battery controller 610 can control the operation of controllable devices in the battery-level protection device 100 and the DC protection device 200. It should be noted that since the passive fuse can actively melt based on current to perform protection operations, it does not need to rely on the controller's control commands to perform protection actions. That is, the battery controller 610 only sends protection commands to the controllable devices in the battery-level protection device 100 and the DC protection device 200, such as contactors, DC circuit breakers, and active fuses.

[0089] The power conversion controller 620 is the controller corresponding to the power conversion module 30, such as a power conversion system controller (PCS). The power conversion controller 620 is mainly used to control the output drive pulses of the power conversion module 30. In this embodiment, the power conversion controller 620 also controls the protection actions of the connection unit 320 and the bypass unit 310 in the cluster-level protection device.

[0090] The relay protection controller 630 is a controller used to control relays and related protective devices to perform protective actions. The relay protection controller 630 can control the operation of the cabin-level protection device 400 and the AC circuit breaker, disconnector and grounding switch in the system-level protection device based on parameters such as AC bus current and AC bus voltage.

[0091] The battery controller 610, power conversion controller 620, and relay protection controller 630 of this application embodiment can communicate through a communication network to achieve comprehensive coordinated control of the energy storage system. For example, if the DC protection device 200 corresponding to the battery controller 610 fails to perform a protection operation, the power conversion controller 620 can control the upstream protection device of the DC protection device 200 to perform backup protection, thereby improving the protection effect of the energy storage system.

[0092] In this embodiment, by configuring different protection levels to the battery controller 610, power conversion controller 620, and relay protection controller 630 respectively, rapid protection can be achieved by utilizing the closest detection information and control capabilities of each controller. At the same time, the communication between the controllers enables coordinated protection of the AC side and DC side, improving the protection effect of the energy storage system and thus enhancing the safety and reliability of the energy storage system.

[0093] Secondly, embodiments of this application also provide a method for protecting an energy storage system.

[0094] Please see Figure 6 , Figure 6This is a schematic flowchart illustrating a protection method for an energy storage system provided in some embodiments of this application. The energy storage system includes: multiple battery compartments, each battery compartment including at least one battery cluster, each battery cluster including a power conversion module and a battery module, the DC terminal of the power conversion module being connected to the battery module, and the AC terminal of the power conversion module being connected in series with an AC bus; the energy storage system also includes: battery-level protection devices, DC protection devices, cluster-level protection devices, compartment-level protection devices, and system-level protection devices; the battery-level protection devices are disposed within the battery modules; the DC protection devices are disposed between the DC terminal of the power conversion module and the battery module; the cluster-level protection devices are disposed between the AC terminal of the battery cluster and the AC bus; the compartment-level protection devices are disposed between adjacent battery compartments or between a battery compartment and the AC bus; the system-level protection devices are disposed between the energy storage system and the AC bus. Figure 6 As shown, the energy storage system protection method includes step S600.

[0095] Step S600: Based on the operating status of the energy storage system, determine the target protection device among battery-level protection devices, DC protection devices, cluster-level protection devices, cabin-level protection devices, and system-level protection devices, and control the target protection device to perform protection operations.

[0096] The operating status of an energy storage system includes normal operation, abnormal operation, shutdown, maintenance, and power-on recovery. This application's embodiments can determine whether the energy storage system is experiencing an anomaly, or whether maintenance or shutdown is required, based on its operating status. This allows for the identification of a target protection device among the multi-level protection devices in the energy storage system, and the control of that target protection device to perform protection operations.

[0097] For example, if the energy storage system is in normal operation, the multi-level protection devices in the energy storage system do not perform protection actions, and the energy storage system operates normally. If an anomaly occurs in the energy storage system, the anomaly is located, and the target protection device is determined based on the anomaly location, and then protection operations are performed. If the energy storage system requires maintenance or shutdown, the multi-level protection devices are sequentially controlled as target protection devices to perform protection operations.

[0098] This application's embodiments can adaptively select the protection level based on the actual operating state of the energy storage system using multi-level protection devices. This avoids all faults directly triggering system-wide shutdowns. The appropriate protection level can be selected based on the fault location and its impact range, allowing for targeted protection operations when a fault occurs in the energy storage system. Furthermore, this application's embodiments can provide coordinated protection for the energy storage system. For example, if a certain protection device cannot clear a fault, backup protection can be provided through other protection devices. This not only achieves comprehensive protection for the energy storage system but also reduces the protection blind spots caused by independent protection actions between the DC and AC sides of the energy storage system, improving the safety and reliability of the energy storage system.

[0099] In some embodiments, the protection levels of the battery-level protection device, DC protection device, cluster-level protection device, cabin-level protection device, and system-level protection device increase sequentially. The energy storage system protection method further includes: in response to the failure of the protection operation of the target protection device, controlling the next-level protection device of the target protection device to perform a protection operation.

[0100] The multi-level protection devices in this application embodiment have sequentially corresponding protection levels. If the protection operation of the target protection device fails, the next-level protection device is controlled to perform a protection operation. The failure of the target protection device's protection operation includes: the target protection device failing to complete the state transition within a preset time; the feedback state of the target protection device after performing the protection operation being inconsistent with the target state; and the target protection device still detecting an abnormality in its operating state after performing the protection operation.

[0101] This application embodiment sets progressively higher protection levels and provides backup protection by setting an upper-level protection device. When the lower-level protection device cannot clear the fault, the upper-level protection device can expand the isolation range and clear the fault, which has a better fault tolerance rate and can improve the safety and reliability of the energy storage system.

[0102] In some embodiments, the energy storage system protection method further includes: acquiring operating data of the energy storage system, the operating data including at least one of current, voltage, temperature or pressure; and determining the operating status of the energy storage system based on the operating data.

[0103] Operational data is data used to characterize the current state of an energy storage system. Operational data can be collected by data detection devices, such as operational data from battery modules, operational data corresponding to power conversion control modules, and operational data corresponding to relays. This application embodiment does not limit the method of acquiring operational data.

[0104] Current data is used to characterize the charge / discharge state of the battery module or the operating state of the power conversion module, and can be obtained through a current sensor. Voltage is the voltage corresponding to the battery module, power conversion module, or battery cluster, and can be obtained through a voltage sampling circuit. Temperature can be the temperature of different areas of the energy storage system, used to characterize the thermal state of the energy storage system, and can be obtained through a temperature sensor. Pressure is the gas pressure within the energy storage system, such as characterizing the generation of gas inside the battery, the expansion or depressurization state of the casing within the battery module, and can be obtained through a pressure sensor.

[0105] For example, embodiments of this application can compare operating data such as current, voltage, temperature, or pressure with preset thresholds, and determine that the energy storage system is in an abnormal state when the operating data exceeds the preset thresholds. In some implementations, the operating state of the energy storage system can also be determined based on the rate of change of the operating data.

[0106] This application embodiment acquires operational data such as current, voltage, temperature, or pressure, and determines the operating status of the energy storage system based on the operational data. This enables early identification of internal anomalies, thereby providing a more accurate basis for the selection and operation of graded protection devices.

[0107] The energy storage system protection method of this application embodiment will be described below through an example.

[0108] Please see Figure 7 , Figure 7 This is a flowchart illustrating another energy storage system protection method provided in some embodiments of this application. Figure 7 As shown, the energy storage system protection method includes the following steps S701 to S727.

[0109] Step S701: Monitor the operating data of the battery module.

[0110] Operating data can be monitored by the battery management system (BMS), including the voltage, current, temperature, or pressure of the battery modules.

[0111] Step S702: Determine whether the blocking capability of the power conversion controller is exceeded.

[0112] If the energy storage system is determined to be in an abnormal state based on the operating data, determine whether the current abnormal state exceeds the blocking capability of the power converter. If it does not exceed the capability, proceed to step S703; otherwise, proceed to step S710.

[0113] Step S703: Determine whether the wave blocking threshold has been reached.

[0114] If the wave blocking threshold is reached, proceed to step S704; otherwise, proceed to step S707.

[0115] Step S704: Control the power conversion controller to send a blocking command.

[0116] Step S705: Control the DC contactor to disconnect.

[0117] Step S706: Determine whether the DC contactor has successfully disconnected.

[0118] If the DC contactor successfully disconnects, the maintenance process of the energy storage system will begin; if the DC contactor fails to disconnect, proceed to step S710.

[0119] Step S707: Determine whether the threshold for reducing the amount has been reached.

[0120] If the threshold for reducing the credit limit is reached, proceed to step S708; otherwise, proceed to step S709.

[0121] Step S708: Control the power conversion controller to send a derating command.

[0122] Step S704 is executed after step S708.

[0123] Step S709: Determine whether the alarm threshold has been reached.

[0124] If the alarm threshold is reached, an alarm is triggered, and the current abnormal status is reported to the monitoring system; if the alarm threshold is not reached, the process returns to step S701 to continue monitoring the running data.

[0125] Step S710: Determine whether to configure cluster-level active fuses.

[0126] If configured, proceed to step S711; otherwise, proceed to step S712.

[0127] Step S711: Trigger cluster-level active fuse to disconnect.

[0128] After the cluster-level active fuse is tripped, the system maintenance process begins.

[0129] Step S712: Determine whether a DC circuit breaker is configured.

[0130] If configured, proceed to step S713; otherwise, proceed to step S714.

[0131] Step S713: Trigger the DC circuit breaker to open.

[0132] After the DC circuit breaker is disconnected, proceed to step S715.

[0133] Step S714: Determine whether to configure a cluster-level AC circuit breaker.

[0134] If configured, execute step S716; otherwise, execute step S717.

[0135] Step S715: Determine whether the DC circuit breaker tripped within the required time.

[0136] If yes, proceed to the system maintenance process; otherwise, execute step S716.

[0137] Step S716: Trigger the cluster-level AC circuit breaker to disconnect.

[0138] The cluster-level AC circuit breaker is disconnected, and step S718 is executed.

[0139] Step S717: Determine whether a cabin-level AC circuit breaker is configured.

[0140] If configured, execute step S719; otherwise, execute step S720.

[0141] Step S718: Determine whether the cluster-level AC circuit breaker tripped within the required time.

[0142] If yes, proceed to the system maintenance process; otherwise, execute step S719.

[0143] Step S719: Trigger the compartment-level AC circuit breaker to disconnect.

[0144] The cabin-level AC circuit breaker is disconnected, and step S721 is executed.

[0145] Step S720: Trigger the system-level AC circuit breaker.

[0146] The system-level AC circuit breaker is triggered, and the system maintenance process begins.

[0147] Step S721: Determine whether the cabin-level AC circuit breaker tripped within the required time.

[0148] If yes, proceed to the system maintenance process; otherwise, execute step S720.

[0149] Step S722: Continuously monitor the operating data of the power conversion module.

[0150] The operating data of the power conversion module includes current or voltage.

[0151] Step S723: Determine whether the operating data of the power conversion module has reached the set protection value.

[0152] If the condition is met, proceed to step S716; otherwise, return to step S722 for continued monitoring.

[0153] Step S724: Continuously monitor the operating data of the cabin-level relay protection device.

[0154] The operating data of the cabin-level relay protection device includes current or voltage.

[0155] Step S725: Determine whether the operating data of the cabin-level relay protection device has reached the set protection value.

[0156] If the condition is met, proceed to step S719; otherwise, return to step S724 for continued monitoring.

[0157] Step S726: Continuously monitor the operating data of the system-level relay protection device.

[0158] The operating data of system-level relay protection devices include current or voltage.

[0159] Step S727: Determine whether the operating data of the system-level relay protection device has reached the set protection value.

[0160] If the condition is met, proceed to step S720; otherwise, return to step S726 for continued monitoring.

[0161] The embodiments of this application determine the corresponding protection level based on the operating data of the energy storage system, and perform targeted protection operations when the energy storage system fails. The multi-level protection devices correspond to different protection levels. When a certain protection device cannot clear the fault, backup protection can be achieved through other protection devices, so as to achieve comprehensive protection of the energy storage system, reduce the protection blind spot caused by independent protection actions between the DC side and AC side of the energy storage system, and improve the safety and reliability of the energy storage system.

[0162] In some embodiments, the energy storage system protection method further includes: in response to a shutdown maintenance command, controlling the energy storage system to stop power conversion; controlling the protection devices of each protection level to disconnect in sequence from the AC side to the DC side; controlling the energy storage elements in the energy storage system to discharge, and controlling the grounding switch to close after discharge verification to enter the maintenance state.

[0163] During maintenance shutdowns of energy storage systems, the system transitions from a energized state to a safe grounded state to sequentially reduce safety risks during maintenance. For example, the power conversion module stops outputting drive pulses, thus halting active power conversion. Next, controllable connection devices at each level are disconnected sequentially from the AC side to the DC side. For instance, this sequentially involves disconnecting the first AC circuit breaker in the system-level protection devices, the third AC circuit breaker or third disconnecting switch in the cabin-level protection devices, the fourth AC contactor or fourth AC circuit breaker in the cluster-level protection devices, and the first DC contactor or first DC circuit breaker in the DC protection devices.

[0164] Energy storage components include DC bus capacitors, filter capacitors, or other energy storage elements in the power conversion module. After the energy storage system is isolated and powered off, the energy storage components are discharged through a discharge resistor or active discharge circuit, and the complete discharge is verified afterward. Once the discharge verification is successful, the corresponding grounding switch can be closed to enter maintenance mode.

[0165] In this embodiment, the energy storage system is controlled to sequentially perform power-off, isolation, discharge, voltage testing, and grounding steps before shutdown and maintenance, thereby avoiding operation of the isolating switch under load, electric shock from residual voltage, and accidental power supply, and improving the safety of the shutdown and maintenance process.

[0166] The following example illustrates the shutdown and maintenance process of an embodiment of this application.

[0167] Please see Figure 8 , Figure 8 This is a flowchart illustrating the shutdown and maintenance process of an energy storage system provided for some embodiments of this application. For example... Figure 8 As shown, the shutdown and maintenance method for the energy storage system includes the following steps S810 to S860.

[0168] Step S810: Remote shutdown and energy lockout.

[0169] In the event of a confirmed fault in the energy storage system, a shutdown command is sent to the energy storage system to control the power converter of the energy storage system to block the waveform, stop power conversion, and control the energy storage system to enter standby mode. At this time, the circuit breaker between the energy storage system and the AC grid is disconnected.

[0170] Step S820: Disconnect each switching device sequentially from the AC side to the DC side.

[0171] Disconnect the circuit breakers in the system-level protection devices, the circuit breakers or contactors in the cabin-level protection devices and the cluster-level protection devices, and the contactors or circuit breakers in the DC protection devices in sequence.

[0172] Step S830: Inspect the phase-front disconnect switch and grounding control.

[0173] Disconnect the disconnecting switch before each phase, confirm that the disconnecting switch before each phase is in the open and isolated position, and close the grounding switch of the detection phase.

[0174] Step S840: Inspect the cluster pre-stage disconnect switch, the cabin pre-stage disconnect switch, and the grounding control.

[0175] When the disconnecting switch and the grounding switch are set independently, disconnect the cluster-front disconnecting switch and the cabin-front disconnecting switch, confirm that the cluster-front disconnecting switch and the cabin-front disconnecting switch are in the open and isolated positions, and close the grounding switch of the maintenance cluster and the maintenance cabin.

[0176] When the disconnecting switch and the grounding switch are linked, the cluster-front disconnecting switch and the cabin-front disconnecting switch are disconnected. After the cluster-front disconnecting switch and the cabin-front disconnecting switch are disconnected, the grounding switch is closed.

[0177] Step S850: Control the bus capacitor to discharge.

[0178] Wait for the bus capacitor to discharge. If the waiting time is long enough and the bus voltage is less than the safe value, control the discharge resistor or active discharge circuit to discharge the bus capacitor, and detect the bus voltage after the preset discharge time. If the bus voltage is less than or equal to the preset safe voltage, the discharge verification is confirmed to be successful. If the bus voltage is still higher than the preset safe voltage, continue discharging or check the discharge circuit.

[0179] Step S860: Safety measures check before maintenance.

[0180] Check whether temporary grounding wires are suspended on both sides of the battery cluster and battery compartment, and whether warning signs are hung on all disconnected switch handles to indicate that closing the circuit is prohibited. Optionally, a locking procedure can be performed.

[0181] At this point, the energy storage system enters a safe state, and maintenance personnel are able to carry out maintenance.

[0182] In some embodiments, the energy storage system protection method further includes: controlling a grounding switch that is in a closed state to open in response to a power restoration command; and controlling multiple protection level protection devices to close in sequence from the DC side to the AC side.

[0183] Upon completion of maintenance and restoration of the energy storage system, first confirm that maintenance personnel have evacuated, maintenance tools have been removed, and the equipment status meets the restoration conditions. Next, disconnect all grounding switches. After confirming that all grounding switches are in the open state, control the closing of multiple protection levels' devices in sequence from the DC side to the AC side. For example, close the first DC contactor or first DC circuit breaker in the DC protection devices to establish a DC connection between the battery module and the power conversion module; then close the fourth disconnecting switch, fourth AC circuit breaker, and fourth AC contactor in the cluster-level protection devices; subsequently close the third disconnecting switch and third AC circuit breaker in the compartment-level protection devices; finally, close the first disconnecting switch and first AC circuit breaker in the system-level protection devices. During the closing process of each protection level device, status feedback is obtained level by level, and the next protection level device is allowed to close only after the current protection level device has successfully closed.

[0184] In this embodiment, the grounding is removed before power is restored, and the connection is established step by step from the DC side to the AC side. This can avoid the short circuit risk caused by closing the circuit with the grounding on when the energy storage system is powered on, overstepping the power supply, and inconsistent switch states, so that the energy storage system can safely resume operation in the reverse order of shutdown and maintenance.

[0185] The power-on restoration process of this application embodiment will be described below with an example.

[0186] Please see Figure 9 , Figure 9 This is a schematic diagram illustrating the power restoration process of an energy storage system provided in some embodiments of this application. For example... Figure 9 As shown, the method for restoring power to the energy storage system includes the following steps S910 to S960.

[0187] Step S910: Clean up the site and remove temporary safety measures.

[0188] After the energy storage system fault repair is completed, clean up the repair site, allow the repair personnel to leave the repair area, remove all temporary grounding wires, retrieve warning signs, and unlock the locks.

[0189] In step S920, the cluster-front grounding switch and the cabin-front grounding switch are disconnected, and the cluster-front isolating switch and the cabin-front isolating switch are closed.

[0190] When the disconnecting switch and the grounding switch are set independently, disconnect the cluster-front grounding switch and the cabin-front grounding switch, and inspect the insulation resistance of the cluster-front and cabin-front stages. If the insulation resistance is greater than or equal to the rated value, close the cluster-front disconnecting switch and the cabin-front disconnecting switch; if the insulation resistance is less than the rated value, find and eliminate the insulation fault point through insulation testing.

[0191] With the disconnecting switch and grounding switch linked, disconnect the cluster-front grounding switch and the cabin-front grounding switch, and simultaneously close the cluster-front disconnecting switch and the cabin-front disconnecting switch. Next, inspect the insulation resistance of the cluster-front stage and the cabin-front stage. If the insulation resistance is greater than or equal to the rated value, proceed to step S930; if the insulation resistance is less than the rated value, locate and eliminate the insulation fault point through insulation testing.

[0192] In step S930, the phase-front grounding switch is opened and the isolating switch is closed.

[0193] Disconnect the grounding switch of the phase under maintenance and test the insulation resistance of the energy storage system. If the insulation resistance is greater than or equal to the rated value, close the phase upstream isolating switch; if the insulation resistance is less than the rated value, locate and eliminate the insulation fault point through insulation testing.

[0194] Step S940: Close each operating switch sequentially from the DC side to the AC side.

[0195] Close the contactor and circuit breaker in the DC protection device, and then close the contactor and circuit breaker in the cluster protection device.

[0196] Step S950: Status confirmation and power-on.

[0197] After confirming that all switches are in the correct state with no alarms or abnormal signals, a system start-up preparation command is remotely issued. The power converter self-test is successful, and the bus capacitors have completed pre-charging.

[0198] Step S960: Restore grid-connected operation.

[0199] The AC side circuit breaker of the closed energy storage system controls the soft start and grid connection of the power converter.

[0200] At this point, the energy storage system resumed normal grid-connected operation.

[0201] The energy storage system of this application embodiment can achieve full current range and full time series protection coverage from minor faults to serious faults through multi-level protection devices, eliminating the protection blind spot of the energy storage system; by setting up a hierarchical protection structure of battery level, DC level, cluster level, cabin level and system level, the hierarchical protection configuration and strict curve matching ensure that the fault is isolated to the minimum extent, and maximize the availability of the energy storage power station.

[0202] The embodiments of this application can directly control the protection action of the DC circuit breaker through the emergency trip command output by the battery management system. In simulation verification, the energy storage system of this application embodiment can shorten the fault clearing time from hundreds of milliseconds to tens of milliseconds, improving the DC side protection efficiency. The energy storage system of this application embodiment is easy to implement, requiring no additional hardware, and is convenient for implementation in new construction and renovation projects. The fusion and judgment of multiple operating data improves the reliability of the protection operation of the energy storage system and enhances the safety of the energy storage system.

[0203] It should be understood that for a detailed explanation of the specific working method and beneficial effects of the above-mentioned energy storage system protection method, please refer to the embodiments of the above-mentioned energy storage system, which will not be repeated here.

[0204] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0205] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0206] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0207] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. An energy storage system, characterized in that, include: Multiple battery compartments (10), each of the battery compartments (10) includes at least one battery cluster (20), the battery cluster (20) includes a power conversion module (30) and a battery module (40), the DC terminal of the power conversion module (30) is connected to the battery module (40), and the AC terminal of the power conversion module (30) is connected in series with the AC bus. The energy storage system also includes: battery-level protection device (100), DC protection device (200), cluster-level protection device, cabin-level protection device (400), system-level protection device, and controller; The battery-level protection device (100) is disposed within the battery module (40); the DC protection device (200) is disposed between the DC terminal of the power conversion module (30) and the battery module (40); the cluster-level protection device is disposed between the AC terminal of the battery cluster (20) and the AC bus; the compartment-level protection device (400) is disposed between adjacent battery compartments (10) or between the battery compartment (10) and the AC bus; the system-level protection device is disposed between the energy storage system and the AC bus. The controller is configured to: determine a target protection device among the battery-level protection device (100), the DC protection device (200), the cluster-level protection device, the cabin-level protection device (400), and the system-level protection device according to the operating status of the energy storage system, and control the target protection device to perform protection operations.

2. The system according to claim 1, characterized in that, The protection levels of the battery-level protection device (100), the DC protection device (200), the cluster-level protection device, the cabin-level protection device (400), and the system-level protection device increase sequentially. The controller is also configured to: In response to the failure of the protection operation of the target protection device, the protection operation of the next-level protection device of the target protection device is controlled to be performed.

3. The system according to claim 1 or 2, characterized in that, The energy storage system includes a busbar connection terminal and a neutral point connection terminal. The system-level protection devices include: a phase line protection unit (510) connected to the busbar connection terminal, and a neutral point protection unit (520) connected to the neutral point connection terminal; wherein, The phase line protection unit (510) includes: a first AC circuit breaker and a first disconnecting switch connected in series, and a plurality of first grounding switches disposed on both sides of the first AC circuit breaker and the first disconnecting switch; The neutral point protection unit (520) includes: a second disconnecting switch and a plurality of second grounding switches disposed on both sides of the second disconnecting switch.

4. The system according to claim 1 or 2, characterized in that, The compartment-level protection device (400) includes: a third disconnect switch and a third grounding switch disposed on the side of the third disconnect switch near the battery compartment (10); or, A third AC circuit breaker and a third disconnecting switch connected in series, and a third grounding switch located on the side of the third disconnecting switch near the battery compartment (10).

5. The system according to claim 4, characterized in that, The compartment protection device (400) is encapsulated in a first housing, which is connected to a grounding terminal; the battery compartment (10) is encapsulated in a second housing, which is connected to the midpoint of the cascaded potential within the battery compartment (10); The cabin-level protection device (400) further includes: a housing grounding switch, the first end of which is insulated through the first housing and connected to the second housing of the battery compartment (10), and the second end of which is connected to the first housing.

6. The system according to claim 1 or 2, characterized in that, The battery cluster (20) includes a first AC connection terminal and a second AC connection terminal; the cluster-level protection device includes: a bypass unit (310) connected between the first AC connection terminal and the second AC connection terminal, and a connection unit (320) connected between the battery cluster (20) and the AC bus, wherein the on / off states of the bypass unit (310) and the connection unit (320) are opposite; wherein, The bypass unit (310) includes a bypass switch; The connection unit (320) includes: a fourth disconnecting switch and a fourth AC contactor connected in series; or, a fourth disconnecting switch, a fourth AC circuit breaker and a fourth AC contactor connected in series.

7. The system according to claim 1 or 2, characterized in that, The DC protection device (200) includes: a first DC contactor and a first fuse connected in series; or, a first DC circuit breaker, a first DC contactor and a first fuse connected in series.

8. The system according to claim 1 or 2, characterized in that, The battery module (40) includes a battery module, and the battery-level protection device (100) includes a second fuse connected in series with the battery module.

9. The system according to claim 1, characterized in that, The controller includes: a battery controller (610), a power conversion controller (620), and a relay protection controller (630) connected in communication; the battery-level protection device (100) and the DC protection device (200) are both connected to the battery controller (610), the cluster-level protection device is connected to the power conversion controller (620); the cabin-level protection device (400) and the system-level protection device are connected to the relay protection controller (630).

10. A protection method for an energy storage system, characterized in that, The energy storage system includes: multiple battery compartments, each battery compartment including at least one battery cluster, each battery cluster including a power conversion module and a battery module, the DC terminal of the power conversion module being connected to the battery module, and the AC terminal of the power conversion module being connected in series with an AC bus; the energy storage system further includes: battery-level protection devices, DC protection devices, cluster-level protection devices, compartment-level protection devices, and system-level protection devices; the battery-level protection devices are disposed within the battery modules; the DC protection devices are disposed between the DC terminal of the power conversion module and the battery module; the cluster-level protection devices are disposed between the AC terminal of the battery cluster and the AC bus; the compartment-level protection devices are disposed between adjacent battery compartments or between a battery compartment and the AC bus; the system-level protection devices are disposed between the energy storage system and the AC bus; the method includes: Based on the operating status of the energy storage system, a target protection device is determined among the battery-level protection device, the DC protection device, the cluster-level protection device, the cabin-level protection device, and the system-level protection device, and the target protection device is controlled to perform protection operations.

11. The method according to claim 10, characterized in that, The protection levels of the battery-level protection device, the DC protection device, the cluster-level protection device, the cabin-level protection device, and the system-level protection device increase sequentially, and the method further includes: In response to the failure of the protection operation of the target protection device, the protection operation of the next-level protection device of the target protection device is controlled to be performed.

12. The method according to claim 10, characterized in that, The method further includes: Acquire operational data of the energy storage system, wherein the operational data includes at least one of current, voltage, temperature, or pressure; The operating status of the energy storage system is determined based on the operating data.

13. The method according to claim 10, characterized in that, The method further includes: In response to a shutdown and maintenance command, the energy storage system is controlled to stop power conversion; The protection devices for each protection level are disconnected in sequence from the AC side to the DC side. The energy storage elements in the energy storage system are controlled to discharge, and after discharge verification, the grounding switch is controlled to close to enter the maintenance state.

14. The method according to claim 10, characterized in that, The method further includes: In response to the power restoration command, the grounding switch, which is in the closed state, is opened; The protection devices of multiple protection levels are controlled to close in sequence from the DC side to the AC side.

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