An overcurrent, overvoltage and undervoltage protection device and method for an energy storage system

Abstract

The application discloses an overcurrent, overvoltage and under-voltage protection device and method for an energy storage system, wherein a DC / DC power module is used to supply power to a controller from an energy storage battery, so that the overcurrent, overvoltage and under-voltage protection device can still work normally when the power grid is abnormal, and the overcurrent, overvoltage and under-voltage protection logic can continuously run. Voltage data of the energy storage battery are collected through a voltage collection port and transmitted to the controller, current data are obtained through a communication port and transmitted to the controller, and then the controller comprehensively judges whether the energy storage battery is in an overvoltage state, an under-voltage state or an overcurrent state, and controls a break-make structure to be disconnected when the energy storage battery is in the overvoltage state, the under-voltage state or the overcurrent state and the duration reaches a delay time. In the working condition that the battery management system is powered off due to abnormal protection of the power grid and the user misoperates to power on again, the application can still independently execute voltage and current monitoring and protection, and the problem of secondary protection failure of the battery management system is avoided.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to an overcurrent, overvoltage and undervoltage protection device and method for energy storage systems. Background Technology

[0002] The safety and lifespan of energy storage systems are highly dependent on the precise control of voltage and current. Voltage and current runaway are the main causes of battery degradation, equipment damage, and even thermal runaway. Current energy storage system voltage and current protection strategies typically rely on a three-level protection architecture of the Battery Management System (BMS) (alarm reminder - shutdown - circuit disconnection). When the system voltage or current exceeds the third-level protection threshold, the BMS will execute the final protection action, forcibly disconnecting the DC circuit and putting the energy storage system into a shutdown state.

[0003] However, this architecture has a potential "protection blind spot" risk: if the energy storage system shuts down due to grid anomalies such as voltage or current abnormalities, and the user turns it back on without knowing or by mistake, the battery management system may fail to trigger secondary protection due to state latching abnormalities or logic defects. This causes the energy storage battery to continue charging and discharging in a damaged state, which not only seriously accelerates the lifespan degradation, but may also completely destroy the safety boundary of the energy storage system and cause a major accident. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings of the prior art, the present invention provides an overcurrent, overvoltage and undervoltage protection device and method for an energy storage system, which aims to solve the problem that when the battery management system is shut down due to grid abnormality protection and then powered on again by user misoperation, the battery management system no longer triggers secondary protection and cannot effectively prevent the energy storage battery from continuing to charge and discharge in a damaged state.

[0005] The technical solution adopted by this invention to solve its technical problem is: an overcurrent, overvoltage, and undervoltage protection device for an energy storage system, comprising:

[0006] A switching structure is connected in series in the output circuit of the energy storage battery. One end of the structure is connected to the energy storage battery, and the other end is connected to the energy storage inverter and the DC / DC power module respectively. The DC / DC power module is used to convert the high DC voltage output by the energy storage battery into a low DC voltage.

[0007] The controller includes a voltage acquisition port, a communication port, and a power supply port; the voltage acquisition port is connected to the energy storage battery and is used to acquire the voltage data of the energy storage battery and transmit it to the controller; the communication port is used to acquire current data; the power supply port is connected to the output terminal of the DC / DC power module and is used to supply power to the controller.

[0008] The controller is connected to the switching structure, the voltage acquisition port, and the communication port, respectively, and is used to determine whether the energy storage battery is in an overvoltage or undervoltage state based on the voltage data, and to determine whether the energy storage battery is in an overcurrent state based on the current data. When the energy storage battery is in an overvoltage, undervoltage, or overcurrent state, the controller starts a delay timer. When the timer reaches the delay time, the controller sends a disconnection control signal to the switching structure to control the switching structure to disconnect.

[0009] As a further improvement of the present invention: the switching structure includes a shunt trip unit, which is electrically connected to the controller and is used to receive the disconnection control signal and perform the disconnection action.

[0010] As a further improvement of the present invention: the on / off structure further includes a micro switch, which is electrically connected to the controller. The micro switch is used to detect the on / off state of the on / off structure and feed back the on / off state signal of the on / off structure to the controller.

[0011] As a further improvement of the present invention: the communication port is used to communicate with the battery management system of the energy storage system to obtain the current data from the battery management system, and upload the voltage data, the on / off state of the on / off structure, and abnormal alarm information such as the overvoltage state, undervoltage state, or overcurrent state to the battery management system.

[0012] As a further improvement of the present invention: the communication port is used to communicate with the current acquisition device of the energy storage system to obtain the current data from the current acquisition device.

[0013] As a further improvement of the present invention: the communication port is an RS485 communication interface, a CAN communication interface, or an Ethernet communication interface.

[0014] As a further improvement of the present invention: the sampling period of the voltage acquisition port is less than or equal to 100ms, and the sampling period of the communication port for acquiring current data is less than or equal to 50ms.

[0015] As a further improvement of the present invention, the controller further includes a parameter setting interface, which is used to set the charging overcurrent protection threshold, the discharging overcurrent protection threshold, the overvoltage protection threshold, the undervoltage protection threshold, and the delay time.

[0016] As a further improvement of the present invention, it also includes an AC / DC power supply module, the input end of which is used to connect to the power grid, and its output end is connected to the power port of the controller, for converting the AC power of the power grid into low-voltage DC power to supply power to the controller when the power grid is normal.

[0017] This invention also provides a method for overcurrent, overvoltage, and undervoltage protection of an energy storage system, applied to the aforementioned overcurrent, overvoltage, and undervoltage protection device for an energy storage system, comprising the following steps:

[0018] Parameter settings: After the controller is powered on, set the charging overcurrent protection threshold, discharging overcurrent protection threshold, overvoltage protection threshold, undervoltage protection threshold, and delay time;

[0019] On / off structure closure: The on / off structure is manually closed, and the micro switch transmits the closure signal to the controller;

[0020] Voltage determination: The controller collects the voltage data of the energy storage battery through the voltage acquisition port, and compares the voltage data with the overvoltage protection threshold and the undervoltage protection threshold respectively. When the voltage data is greater than or equal to the overvoltage protection threshold, the energy storage battery is determined to be in an overvoltage state; when the voltage data is less than or equal to the undervoltage protection threshold, the energy storage battery is determined to be in an undervoltage state.

[0021] Current determination: The controller obtains current data through the communication port, compares the current data with the charging overcurrent protection threshold or the discharging overcurrent protection threshold, and determines whether the energy storage battery is in an overcurrent state.

[0022] Delay judgment: When the energy storage battery is in an overvoltage state, undervoltage state, or overcurrent state, the delay timer is started;

[0023] Disconnection control: When the delay time reaches the specified delay time, the controller sends a disconnection control signal to the on / off structure to control the on / off structure to disconnect.

[0024] As a further improvement of the present invention: in the current determination step, the controller determines whether the current direction is the charging direction or the discharging direction based on the current data;

[0025] When the current direction is the charging direction, the current data is compared with the charging overcurrent protection threshold. If the current data is greater than the charging overcurrent protection threshold, it is determined that the energy storage battery is in an overcurrent state.

[0026] When the current direction is the discharge direction, the current data is compared with the discharge overcurrent protection threshold. If the current data is greater than the discharge overcurrent protection threshold, the energy storage battery is determined to be in an overcurrent state.

[0027] As a further improvement of the present invention: in the voltage judgment step, when it is determined that the energy storage battery is in an overvoltage state or an undervoltage state, the abnormal alarm information such as the overvoltage state or undervoltage state is uploaded to the battery management system through the communication port.

[0028] In the current determination step, when it is determined that the energy storage battery is in an overcurrent state, the abnormal alarm information of the overcurrent state is uploaded to the battery management system through the communication port.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This invention draws power from the energy storage battery to power the controller via a DC / DC power module, ensuring that the overcurrent, overvoltage, and undervoltage protection devices can still operate normally during grid anomalies, and guaranteeing the continuous operation of the overcurrent, overvoltage, and undervoltage protection logic. Voltage data from the energy storage battery is acquired through a voltage acquisition port and transmitted to the controller, while current data is acquired through a communication port and transmitted to the controller. The controller then comprehensively determines whether the energy storage battery is in an overvoltage, undervoltage, or overcurrent state. When the energy storage battery is in an overvoltage, undervoltage, or overcurrent state, a delay timer is initiated. When the duration of the overvoltage, undervoltage, or overcurrent state reaches the delay time, the controller sends a disconnection control signal to the switching structure, controlling the switching structure to disconnect, effectively avoiding malfunctions caused by instantaneous voltage fluctuations. Even after the battery management system is shut down due to grid anomaly protection and then powered on again due to user error, this invention can still independently perform voltage and current monitoring and protection, avoiding the problem of secondary protection failure of the battery management system. Together with the battery management system, it forms a dual protection system, significantly improving the safety and reliability of the energy storage system. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of an overcurrent, overvoltage and undervoltage protection device for an energy storage system according to Embodiment 1 of the present invention.

[0032] Figure 2 This is a flowchart of an overcurrent, overvoltage, and undervoltage protection method for an energy storage system according to Embodiment 2 of the present invention.

[0033] Figure 3 This is a flowchart of an overcurrent, overvoltage, and undervoltage protection method for an energy storage system according to Embodiment 3 of the present invention. Detailed Implementation

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0035] It should be understood that the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0036] It should be understood that specific details are provided in the following description to facilitate a complete understanding of the exemplary embodiments. However, those skilled in the art will understand that the exemplary embodiments can be implemented without these specific details. For example, the system may be shown in block diagrams to avoid obscuring the example with unnecessary details. In other instances, well-known processes, structures, and techniques may be shown without unnecessary details to avoid obscuring the exemplary embodiments.

[0037] Example 1:

[0038] Please see Figure 1 An overcurrent, overvoltage, and undervoltage protection device for an energy storage system, comprising:

[0039] The on / off structure is connected in series in the output circuit of the energy storage battery. One end of the structure is connected to the energy storage battery, and the other end is connected to the energy storage inverter (PCS) and the DC / DC power module respectively. The DC / DC power module is used to convert the high DC voltage output by the energy storage battery into a low DC voltage.

[0040] The controller includes a voltage acquisition port, a communication port, and a power supply port; the voltage acquisition port is connected to the energy storage battery and is used to acquire the voltage data of the energy storage battery and transmit it to the controller; the communication port is used to acquire current data; the power supply port is connected to the output terminal of the DC / DC power module and is used to supply power to the controller.

[0041] The controller is connected to the switching structure, the voltage acquisition port, and the communication port, respectively, and is used to determine whether the energy storage battery is in an overvoltage or undervoltage state based on the voltage data, and to determine whether the energy storage battery is in an overcurrent state based on the current data. When the energy storage battery is in an overvoltage, undervoltage, or overcurrent state, the controller starts a delay timer. When the timer reaches the delay time, the controller sends a disconnection control signal to the switching structure to control the switching structure to disconnect.

[0042] One end of the switching structure is connected to the energy storage battery, and the other end is connected to the DC / DC power module. The DC / DC power module is connected to the power port of the controller. When the power grid is abnormal and the switching structure is closed, the DC / DC power module can draw power from the energy storage battery and convert it into low DC voltage to power the controller. This ensures that the overcurrent, overvoltage and undervoltage protection devices can still work normally when the power grid is abnormal, and ensures the continuous operation of the overcurrent, overvoltage and undervoltage protection logic.

[0043] Voltage data of the energy storage battery is acquired through the voltage acquisition port and transmitted to the controller. Current data is acquired through the communication port and transmitted to the controller. The controller then comprehensively judges whether the energy storage battery is in an overvoltage, undervoltage, or overcurrent state. When the energy storage battery is in an overvoltage, undervoltage, or overcurrent state, a delay timer is started. When the duration of the overvoltage, undervoltage, or overcurrent state reaches the delay time, the controller sends a disconnection control signal to the switching structure to control the switching structure to disconnect, effectively avoiding malfunctions caused by instantaneous voltage fluctuations.

[0044] This invention can still independently perform voltage and current monitoring and protection even when the battery management system is shut down due to grid anomaly protection and then powered on again due to user error, thus avoiding the problem of secondary protection failure of the battery management system; together with the battery management system, it forms a dual protection, significantly improving the safety and reliability of the energy storage system.

[0045] In some embodiments, the switching structure includes a shunt trip unit electrically connected to the controller, the shunt trip unit being used to receive the disconnection control signal and perform a disconnection action.

[0046] The shunt trip unit is electrically connected to the controller, allowing the controller to remotely control the shunt trip unit to perform a disconnection action via electrical signals. This eliminates the need for manual on-site operation and automates overcurrent, overvoltage, and undervoltage protection. Upon receiving the disconnection control signal, the shunt trip unit reliably executes the disconnection action, ensuring the effective implementation of overcurrent, overvoltage, and undervoltage protection.

[0047] In some embodiments, the on / off structure further includes a micro switch electrically connected to the controller. The micro switch is used to detect the on / off state of the on / off structure and feed back the on / off state signal of the on / off structure to the controller.

[0048] By electrically connecting a microswitch to the controller, the microswitch can detect the open or closed state of the switching mechanism in real time and feed back the status signal to the controller, enabling the controller to accurately grasp the actual on / off state of the switching mechanism. After the controller issues a disconnection control signal, it can confirm whether the switching mechanism has been successfully disconnected through the on / off status signal fed back by the microswitch, ensuring the reliability of overcurrent, overvoltage, and undervoltage protection actions.

[0049] In some implementations, the communication port is used to communicate with the battery management system (BMS) of the energy storage system to obtain the current data from the battery management system and upload the voltage data, the on / off status of the switching structure, and abnormal alarm information such as overvoltage, undervoltage, or overcurrent status to the battery management system.

[0050] By communicating with the battery management system via the communication port, current data can be obtained from the battery management system without the need for additional current acquisition hardware. This simplifies the structure of overcurrent, overvoltage, and undervoltage protection devices and reduces costs. At the same time, the controller can upload abnormal alarm information such as overcurrent, overvoltage, and undervoltage states to the battery management system, realizing two-way information interaction. This allows the battery management system to know the protection action status of the overcurrent, overvoltage, and undervoltage protection devices in a timely manner, facilitating comprehensive judgment and recording management. This effectively improves the informatization level and collaborative management capability of overcurrent, overvoltage, and undervoltage protection in the energy storage system.

[0051] In some implementations, the communication port is used to communicate with a current acquisition device of the energy storage system to obtain the current data from the current acquisition device.

[0052] By communicating with the current acquisition device through the communication port, current data can be obtained directly from the current acquisition device without relying on the battery management system to provide current information, thus enhancing the independence of the overcurrent, overvoltage and undervoltage protection devices and the system compatibility.

[0053] In some implementations, the communication port is an RS485 communication interface, a CAN communication interface, or an Ethernet communication interface.

[0054] In some implementations, the sampling period of the voltage acquisition port is less than or equal to 100ms, and the sampling period of the communication port for acquiring current data is less than or equal to 50ms, thereby avoiding inaccurate data or incorrect judgments caused by sampling periods that are too long or too short.

[0055] In some embodiments, the controller further includes a parameter setting interface for setting charging overcurrent protection threshold, discharging overcurrent protection threshold, overvoltage protection threshold, undervoltage protection threshold, and delay time.

[0056] Among them, the charging overcurrent protection threshold is used to compare whether the energy storage system is overcurrent during the charging state;

[0057] The discharge overcurrent protection threshold is used to compare whether the energy storage system is overcurrent under discharge conditions.

[0058] Overvoltage protection threshold is used to compare whether the energy storage system is overvoltage;

[0059] The undervoltage protection threshold is used to compare whether the energy storage system is undervoltage.

[0060] The delay time is used to delay the execution of protective actions by the energy storage system to avoid malfunctions caused by instantaneous fluctuations in current or voltage.

[0061] In some embodiments, an AC / DC power module is also included. The input terminal of the AC / DC power module is used to connect to the power grid, and its output terminal is connected to the power port of the controller. The AC power is used to convert the AC power from the power grid into low-voltage DC power to supply power to the controller when the power grid is normal.

[0062] By setting up an AC / DC power module, power is drawn from the grid and converted to low-voltage DC to power the controller when the grid is normal. This eliminates the need for the controller to consume energy from the energy storage battery when the grid is normal, effectively reducing the energy consumption of the energy storage battery and extending its standby time and cycle life. At the same time, the AC / DC power module and the DC / DC power module work together to form a dual-power supply architecture. The two complement each other, enabling the controller to obtain a stable power supply under both normal and abnormal grid conditions. This significantly improves the reliability of the power supply for overcurrent, overvoltage, and undervoltage protection devices and its adaptability to complex operating conditions.

[0063] The output terminal of the AC / DC power module is connected to the auxiliary electrical equipment of the energy storage system, and is used to supply power to the auxiliary electrical equipment when the power grid is normal. The output terminal of the DC / DC power module is also connected to the auxiliary electrical equipment of the energy storage system, and is used to supply power to the auxiliary electrical equipment when the power grid is abnormal.

[0064] Under normal power grid conditions, the power grid converts low AC voltage (220Vac) to low DC voltage (24Vdc) through the AC / DC module to supply power to auxiliary electrical equipment and controllers.

[0065] In the event of a grid anomaly, the energy storage battery converts the high-voltage DC (250Vdc~1500Vdc) to a low-voltage DC (24Vdc) through the DC / DC power module to supply power to auxiliary electrical equipment and the controller. This allows the controller to determine whether to perform overcurrent, overvoltage, and undervoltage protection on the energy storage battery when the grid is abnormal and the switching structure is closed.

[0066] By providing dual power supplies to the auxiliary equipment and controller through AC / DC power modules and DC / DC power modules respectively, uninterrupted power supply to the auxiliary equipment and controller is achieved under both normal and abnormal power grid conditions.

[0067] The DC side of the energy storage converter is connected to the energy storage battery via the switching structure, and the AC side of the energy storage converter is connected to the power grid and the user load. In the event of a power grid anomaly, the energy storage converter operates in inverter mode, converting the DC power from the energy storage battery into AC power to supply the user load.

[0068] Example 2:

[0069] Please see Figure 2 A method for overcurrent, overvoltage, and undervoltage protection of an energy storage system, applied to an overcurrent, overvoltage, and undervoltage protection device for an energy storage system as described in Embodiment 1, includes the following steps:

[0070] S01, Manual closing switch structure;

[0071] S02, The controller acquires the closing signal;

[0072] S03. Determine if the battery voltage is normal. If yes, proceed to step S04; if no, proceed to step S09.

[0073] S04. Is the battery current normal? If yes, proceed to step S03; if no, proceed to step S05.

[0074] S05. Determine if the battery is overcharged. If yes, upload the overcharge signal to the BMS and proceed to step S06; otherwise, proceed to step S07.

[0075] S06. Determine whether the duration of the charging overcurrent is greater than or equal to the delay time. If yes, proceed to step S021; if no, proceed to step S05.

[0076] S07. Determine if the battery is over-discharged. If yes, upload the over-discharge signal to the BMS and proceed to step S08; otherwise, proceed to step S04.

[0077] S08. Determine whether the duration of the discharge overcurrent is greater than or equal to the delay time. If yes, proceed to step S021; if no, proceed to step S07.

[0078] S09. Determine if the battery is low on voltage. If yes, proceed to step S010; if no, proceed to step S015.

[0079] S010. Determine if the battery is in standby mode or charging normally. If yes, proceed to step S09; if no, proceed to step S011.

[0080] S011. Determine if the battery is in a discharged state. If yes, upload a battery low voltage and prevent discharge signal to the BMS and proceed to step S012; otherwise, proceed to step S013.

[0081] S012. Determine whether the duration of the discharge state is greater than or equal to the delay time. If yes, proceed to step S021; if no, proceed to step S011.

[0082] S013. Determine if the battery is overcharged. If yes, upload the overcharge signal to the BMS and proceed to step S014; otherwise, proceed to step S010.

[0083] S014. Determine whether the duration of the charging overcurrent is greater than or equal to the delay time. If yes, proceed to step S021; if no, proceed to step S013.

[0084] S015. Determine if the battery is overvoltage? If yes, proceed to step S016; if no, proceed to step S03.

[0085] S016. Determine if the battery is in standby or normal discharge state. If yes, proceed to step S015; if no, proceed to step S017.

[0086] S017. Determine if the battery is charging. If yes, send an overvoltage signal to the BMS and disable charging. Proceed to step S018. If no, proceed to step S019.

[0087] S018. Determine whether the duration of the charging state is greater than or equal to the delay time. If yes, proceed to step S021; if no, proceed to step S017.

[0088] S019. Determine if the battery is over-discharged. If yes, upload the over-discharge signal to the BMS and proceed to step S020; otherwise, proceed to step S016.

[0089] S020. Determine whether the duration of the discharge overcurrent is greater than or equal to the delay time. If yes, proceed to step S021; if no, proceed to step S019.

[0090] S021, The controller outputs a disconnection control signal, and the on / off structure is disconnected.

[0091] Example 3:

[0092] Please see Figure 3 This embodiment discloses an overcurrent, overvoltage, and undervoltage protection method for an energy storage system, applied to an overcurrent, overvoltage, and undervoltage protection device for an energy storage system as described in Embodiment 1. In this embodiment, the discharge current is defined as a positive value, the charging current as a negative value, and the standby current as 0. After the controller is powered on, a charging overcurrent protection threshold I is set. min Discharge overcurrent protection threshold I max Overvoltage protection threshold U max Undervoltage protection threshold U min and delay time T dT represents the duration of the overvoltage, undervoltage, or overcurrent condition.

[0093] Specifically, an overcurrent, overvoltage, and undervoltage protection method for an energy storage system according to this embodiment includes the following steps:

[0094] S1, Manual closing switch structure;

[0095] S2. The controller acquires a closed signal; the controller acquires the voltage of the energy storage battery as U through the voltage acquisition port and the current as I through the communication port;

[0096] S3, Determine U min <U<U max Is it valid? If yes, proceed to step S4; if no, proceed to step S9.

[0097] S4, Judgment I min <I<I max Is it valid? If yes, proceed to step S3; if no, proceed to step S5.

[0098] S5. Determine if I ≤ I min Is the condition met? If yes, upload the charging overcurrent signal to the BMS and proceed to step S6; if no, proceed to step S7.

[0099] S6. Determine if T≥T d Is it valid? If yes, proceed to step S21; if no, proceed to step S5.

[0100] S7. Determine if I ≥ I max Is it valid? If yes, upload the discharge overcurrent signal to the BMS and proceed to step S8; if no, proceed to step S4.

[0101] S8. Determine if T≥T d Is it valid? If yes, proceed to step S21; if no, proceed to step S7.

[0102] S9. Determine if U≤U min Is it valid? If yes, proceed to step S10; if no, proceed to step S15.

[0103] S10, Judgment I min Is <I≤0 true? If yes, proceed to step S9; if no, proceed to step S11.

[0104] S11. Determine if I > 0 is true. If yes, upload a battery low voltage and prevent discharge signal to the BMS and proceed to step S12; otherwise, proceed to step S13.

[0105] S12. Determine if T≥T d Is it valid? If yes, proceed to step S21; if no, proceed to step S11.

[0106] S13. Determine if I≤I min Is the condition met? If yes, upload the charging overcurrent signal to the BMS and proceed to step S14; if no, proceed to step S10.

[0107] S14. Determine if T≥T d Is it valid? If yes, proceed to step S21; if no, proceed to step S13.

[0108] S15. Determine if U≥U max Is it valid? If yes, proceed to step S16; if no, proceed to step S3.

[0109] S16. Determine whether 0 ≤ I < I max Is it valid? If yes, proceed to step S15; if no, proceed to step S17.

[0110] S17. Determine if I < 0 is true. If yes, upload the battery overvoltage signal, disable the charging signal to the BMS, and proceed to step S18; otherwise, proceed to step S19.

[0111] S18. Determine if T≥T d Is it valid? If yes, proceed to step S21; if no, proceed to step S17.

[0112] S19. Determine if I ≥ I max Is it valid? If yes, upload the discharge overcurrent signal to the BMS and proceed to step S20; if no, proceed to step S16.

[0113] S20. Judgment T≥T d Is it valid? If yes, proceed to step S21; if no, proceed to step S19.

[0114] S21, The controller outputs a disconnection control signal, and the on / off structure is disconnected.

[0115] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0116] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. An overcurrent, overvoltage, and undervoltage protection device for an energy storage system, characterized in that: include: The on / off structure is connected in series in the output circuit of the energy storage battery. One end of the structure is connected to the energy storage battery, and the other end is connected to the energy storage inverter and the DC / DC power module respectively. The DC / DC power module is used to convert the high DC voltage output by the energy storage battery into a low DC voltage. The controller includes a voltage acquisition port, a communication port, and a power supply port; the voltage acquisition port is connected to the energy storage battery and is used to acquire the voltage data of the energy storage battery and transmit it to the controller; the communication port is used to acquire current data; the power supply port is connected to the output terminal of the DC / DC power module and is used to supply power to the controller. The controller is connected to the switching structure, the voltage acquisition port, and the communication port, respectively, and is used to determine whether the energy storage battery is in an overvoltage or undervoltage state based on the voltage data, and to determine whether the energy storage battery is in an overcurrent state based on the current data. When the energy storage battery is in an overvoltage, undervoltage, or overcurrent state, the controller starts a delay timer. When the timer reaches the delay time, the controller sends a disconnection control signal to the switching structure to control the switching structure to disconnect.

2. The overcurrent, overvoltage, and undervoltage protection device for an energy storage system according to claim 1, characterized in that: The switching structure includes a shunt trip unit, which is electrically connected to the controller. The shunt trip unit is used to receive the disconnection control signal and perform the disconnection action.

3. The overcurrent, overvoltage, and undervoltage protection device for an energy storage system according to claim 2, characterized in that: The on / off structure also includes a micro switch, which is electrically connected to the controller. The micro switch is used to detect the on / off state of the on / off structure and feed back the on / off state signal of the on / off structure to the controller.

4. The overcurrent, overvoltage, and undervoltage protection device for an energy storage system according to claim 1, characterized in that: The communication port is used to communicate with the battery management system of the energy storage system to obtain the current data from the battery management system and upload the voltage data, the on / off state of the on / off structure, and the overvoltage state, undervoltage state, or overcurrent state to the battery management system.

5. The overcurrent, overvoltage, and undervoltage protection device for an energy storage system according to claim 1, characterized in that: The communication port is used to communicate with the current acquisition device of the energy storage system in order to obtain the current data from the current acquisition device.

6. The overcurrent, overvoltage, and undervoltage protection device for an energy storage system according to claim 1, characterized in that: The communication port is an RS485 communication interface, a CAN communication interface, or an Ethernet communication interface.

7. The overcurrent, overvoltage, and undervoltage protection device for an energy storage system according to claim 1, characterized in that: The sampling period of the voltage acquisition port is less than or equal to 100ms, and the sampling period of the communication port for acquiring current data is less than or equal to 50ms.

8. The overcurrent, overvoltage, and undervoltage protection device for an energy storage system according to claim 7, characterized in that: The controller also includes a parameter setting interface, which is used to set the charging overcurrent protection threshold, the discharging overcurrent protection threshold, the overvoltage protection threshold, the undervoltage protection threshold, and the delay time.

9. The overcurrent, overvoltage, and undervoltage protection device for an energy storage system according to claim 1, characterized in that: It also includes an AC / DC power module, the input of which is connected to the power grid, and its output is connected to the power port of the controller, which is used to convert the AC power of the power grid into low-voltage DC power to supply power to the controller when the power grid is normal.

10. A method for overcurrent, overvoltage, and undervoltage protection of an energy storage system, applied to an overcurrent, overvoltage, and undervoltage protection device for an energy storage system as described in any one of claims 1 to 9, characterized in that: Includes the following steps: Set the charging overcurrent protection threshold, discharging overcurrent protection threshold, overvoltage protection threshold, undervoltage protection threshold, and delay time; The voltage data of the energy storage battery is collected, and the voltage data is compared with the overvoltage protection threshold and the undervoltage protection threshold respectively. When the voltage data is greater than or equal to the overvoltage protection threshold, it is determined that the energy storage battery is in an overvoltage state. When the voltage data is less than or equal to the undervoltage protection threshold, it is determined that the energy storage battery is in an undervoltage state. Acquire current data and compare the current data with the charging overcurrent protection threshold or the discharging overcurrent protection threshold to determine whether the energy storage battery is in an overcurrent state. When the energy storage battery is in an overvoltage state, undervoltage state, or overcurrent state, a time delay timer is activated. When the delay time reaches the specified delay time, the control switch structure is disconnected.

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