A method and device for preventing reverse flow control and an energy storage system

Abstract

This application discloses an anti-reverse current control method, device, and energy storage system. The anti-reverse current control method determines whether reverse power occurs at the grid connection interface while the energy storage device is in a discharging state. If so, it controls the energy storage power converter to gradually reduce the output power value and controls the reverse power protection device to enter a locked state, making the grid connection switch in a conducting state. It acquires the current output power of the energy storage power converter and the duration of the reverse power, compares the duration with a preset time threshold, and compares the current output power with a first power threshold. When the duration of the reverse power is less than the preset time threshold, it controls the reverse power protection device to maintain the locked state. When the duration of the reverse power is greater than or equal to the preset time threshold, but the output power is still less than the first power threshold, it controls the reverse power protection device to exit the locked state. This application can effectively balance the operational reliability of the energy storage system with the accuracy of protection actions.

Description

Technical Field

[0001] This application relates to the field of electronic technology, specifically to an anti-backflow control method, device, and energy storage system. Background Technology

[0002] Electrochemical energy storage devices installed in user-side scenarios such as industrial parks are typically required to operate in a "self-consumption, no backfeeding to the grid" mode. When reverse current occurs, causing backfeeding to the grid, the energy storage system needs to be equipped with anti-reverse current protection to prevent the stored energy from being fed back to the grid, thus avoiding grid-related performance evaluations. Therefore, anti-reverse current protection is crucial for the normal operation and profitability of new industrial and commercial lithium-ion energy storage devices.

[0003] Currently, the backflow prevention measures commonly used in user-side electrochemical energy storage devices are relatively simple and ineffective. Commonly used backflow prevention measures either lack timely response, leading to untimely control and backflow; or they have fast detection and response speeds, meeting timely response requirements, but their protection logic is relatively simple. Once a backflow occurs (even a brief, minor fluctuation), it triggers a trip, causing frequent grid disconnection of the energy storage device. Frequent opening and closing of the grid-connected switch affects its lifespan, thus reducing the reliability of the energy storage equipment. Therefore, there is an urgent need for a backflow prevention protection technology that can balance timely response with the reliability of energy storage devices. Summary of the Invention

[0004] This application provides a backflow prevention control method, device, and energy storage system, which can alleviate the problem that current backflow prevention protection measures cannot simultaneously address the timeliness and reliability of energy storage equipment.

[0005] This application provides an anti-backflow control method applied to an energy storage system. The energy storage system includes an energy storage device, an energy storage power converter, a grid-connected switch, and a reverse power protection device. The grid-connected switch is used to connect to the power grid. The energy storage power converter is connected to both the grid-connected switch and the energy storage device. The reverse power protection device is used to connect to the grid connection interface and is connected to the grid-connected switch. The anti-backflow control method includes the following steps:

[0006] When the energy storage device is in a discharging state, determine whether reverse power appears at the grid connection port; If so, the energy storage power converter is controlled to gradually reduce the output power value, and the reverse power protection device is controlled to enter the lockout state, so that the grid-connected switch is in the conducting state. The current output power and the duration of the reverse power of the energy storage power converter are obtained, and the duration of the reverse power is compared with a preset time threshold, and the current output power is compared with a first power threshold. When the duration of reverse power is less than a preset time threshold, the reverse power protection device is controlled to remain in a locked state; when the duration of reverse power is greater than or equal to the preset time threshold, and the output power is still less than the first power threshold, the reverse power protection device is controlled to exit the locked state, causing the grid-connected switch to disconnect.

[0007] This application provides an anti-backflow control method applied to an energy storage system. The energy storage system includes an energy storage device, an energy storage power converter, a grid-connected switch, a reverse power protection device, and a photovoltaic power generation device. The grid-connected switch and the photovoltaic power generation device are used for grid connection. The energy storage power converter is connected to the grid-connected switch and the energy storage device respectively. The reverse power protection device is used for grid connection and is connected to the grid-connected switch. The anti-backflow control method includes the following steps: When the energy storage device is in a discharging state, determine whether reverse power appears at the grid connection port; If so, the energy storage power converter is controlled to gradually reduce the output power value, and the reverse power protection device is controlled to enter the lockout state, so that the grid-connected switch is in the conducting state. The duration of the reverse power is compared with a preset time threshold, and the output power is compared with a first power threshold and a second power threshold; the second power threshold is greater than the first power threshold. When the duration of reverse power is greater than or equal to a preset time threshold and the output power is greater than or equal to a second power threshold, the reverse power protection device is locked, so that the grid-connected switch remains on. When the duration of reverse power is greater than or equal to a preset time threshold and the output power is less than a first power threshold, the reverse power protection device is controlled to exit the lockout state, causing the grid-connected switch to disconnect.

[0008] In some embodiments of the anti-reverse current control method, after the steps of comparing the duration of reverse power with a preset time threshold and comparing the output power with a first power threshold and a second power threshold, the method further includes: If the duration of reverse power is less than a preset time threshold, the reverse power protection device will be kept in a locked state.

[0009] In some embodiments of the anti-reverse current control method, after determining whether reverse power occurs at the grid connection port when the energy storage device is in a discharging state, the method includes: When no reverse power is detected at the grid connection port, the reverse power protection device is locked, which keeps the grid connection switch in the ON state.

[0010] In some embodiments of the anti-backflow control method, the anti-backflow control method further includes: When the energy storage device is charging, the reverse power protection device is locked, which keeps the grid-connected switch in the on state.

[0011] In some embodiments of the anti-reverse current control method, determining whether reverse power occurs at the gateway interface specifically includes: Collect and connect the current and voltage signals output from the gateway interface; Calculate real-time power based on current and voltage signals; The direction of real-time power is determined based on the preset power direction. When the direction of real-time power is positive, it is determined that no reverse power has appeared at the gate. If the real-time power is reverse power, then reverse power is determined to have appeared at the gateway interface.

[0012] In some embodiments of the anti-reverse current control method, the step of calculating real-time power based on current and voltage signals includes: Filtering is performed on current and voltage signals; The real-time power is calculated from the filtered current and voltage signals.

[0013] This application embodiment also provides an anti-backflow control device, which includes: The judgment module is used to determine whether reverse power appears at the gate of the grid when the energy storage device is in the discharge state. If reverse power appears at the gate of the grid, the first judgment signal is output; if reverse power does not appear at the gate of the grid, the second judgment signal is output. The control module is used to control the reverse power protection device to enter the lockout state according to the first judgment signal and the second judgment signal, so that the grid-connected switch is in the conducting state, and to control the energy storage power converter to gradually reduce the output power value according to the first judgment signal. The comparison module is connected to the control module and the judgment module respectively. The comparison module is used to obtain the current output power and the duration of the reverse power of the energy storage power converter according to the first judgment signal. When the duration of the reverse power is found to be less than a preset time threshold, the first comparison signal is output. When the duration of the reverse power is greater than or equal to the preset time threshold and the output power is still less than the first power threshold, the second comparison signal is output. The control module is also used to control the reverse power protection device to maintain the locked state according to the first comparison signal, and to control the reverse power protection device to exit the locked state according to the second comparison signal, so that the grid-connected switch is disconnected.

[0014] This application also provides an energy storage system, which includes an energy storage device, an energy storage power converter, a grid-connected switch, a reverse power protection device, and an anti-reverse current control device. The grid-connected switch is used to connect to the power grid. The energy storage power converter is connected to both the grid-connected switch and the energy storage device. The reverse power protection device is used to connect to the grid-connected port and is connected to the grid-connected switch. The anti-reverse current control device is used to connect to the grid-connected port and is connected to both the reverse power protection device and the energy storage power converter. The anti-reverse current control device is used to execute the anti-reverse current control method described above.

[0015] This application embodiment also provides an energy storage system, which includes an energy storage device, an energy storage power converter, a grid-connected switch, a reverse power protection device, a photovoltaic power generation device, and an anti-reverse current control device. The grid-connected switch and the photovoltaic power generation device are used to connect to the power grid. The energy storage power converter is connected to the grid-connected switch and the energy storage device respectively. The reverse power protection device is used to connect to the grid-connected port and is connected to the grid-connected switch. The anti-reverse current control device is used to execute the anti-reverse current control method as described above.

[0016] This application provides a reverse current prevention control method, device, and energy storage equipment. The reverse current prevention control method, when reverse power occurs at the grid connection interface, prioritizes active suppression by adjusting the output power of the energy storage power converter. Combined with a reverse power blocking protection device, this prevents frequent malfunctions of the grid connection switch due to short-term reverse power disturbances, maintaining continuous operation of the energy storage system and the grid, and improving the stability and continuity of the energy storage system's grid connection. Simultaneously, by combining the duration of reverse power and the output power of the energy storage power converter as dual judgment conditions, it can accurately distinguish between short-term fluctuating reverse power and long-term abnormal reverse power. In scenarios where active adjustment methods cannot eliminate the reverse power anomaly, it promptly triggers the grid connection switch to disconnect, achieving dual electrical protection for both the grid side and the local energy storage system. This prevents long-term reverse power from adversely affecting grid operation safety and related equipment, thus balancing the reliability of the energy storage system operation with the accuracy of protection actions. Attached Figure Description

[0017] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0018] Figure 1 This is a first structural block diagram of an energy storage system provided in an embodiment of this application.

[0019] Figure 2 This is a second structural block diagram of an energy storage system provided in an embodiment of this application.

[0020] Figure 3 This is a third structural block diagram of an energy storage system provided in an embodiment of this application.

[0021] Figure 4 This is a schematic diagram of the first type of anti-backflow control method provided in the embodiments of this application.

[0022] Figure 5 This is a schematic diagram of step S100 in the anti-backflow control method provided in the embodiments of this application.

[0023] Figure 6 This is a fourth structural block diagram of the energy storage system provided in the embodiments of this application.

[0024] Figure 7 This is a schematic diagram of the second process of the anti-backflow control method provided in the embodiments of this application.

[0025] Figure 8 This is a structural block diagram of the anti-backflow control device provided in the embodiments of this application. Detailed Implementation

[0026] 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 scope of protection of this application.

[0027] Furthermore, 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. Features thus 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.

[0028] This application provides an anti-backflow control method, device, and energy storage system, which will be described in detail below.

[0029] Please see Figure 1 , Figure 1 This is a first structural block diagram of an energy storage system provided in an embodiment of this application. The energy storage system includes an energy storage device 11, an energy storage power converter 12, a grid-connected switch 13, and an energy storage management device 14. The grid-connected switch, the energy storage power converter 12, and the energy storage device 11 are connected in sequence. The grid-connected switch 13 is used to connect to the power grid 20, and the energy storage management device 14 is used to connect to the grid interface 15 and is connected to the energy storage power converter 12.

[0030] The grid connection port 15 is a core node connecting the energy storage device 11, load 30, and the power grid 20. It serves as the interface for power exchange between the energy storage device 11 and the power grid 20. Through the grid connection port 15, data such as power, voltage, and current transmitted bidirectionally between the power grid 20 and the energy storage device 11 can be collected. The grid connection switch 13 can be used to control the on / off state of the power transmission path between the energy storage device 11 and the power grid 20. The energy storage power converter 12 can perform bidirectional AC / DC conversion, rectifying the AC power from the power grid 20 into DC power to safely and stably charge the energy storage device 11. Simultaneously, it can also invert the DC power from the energy storage device 11 into AC power, outputting AC power with the same frequency, phase, and voltage level as the power grid 20, which is then fed into the AC bus for use by the load 30 or fed into the grid as needed. The energy storage management device 14 can be used to control the operation of the energy storage power converter 12, adjusting the charging and discharging power, etc.

[0031] The technical approach of using the above-mentioned energy storage system for backflow protection is as follows: when the energy storage management device 14 detects a backflow signal at the grid connection port 15, the energy storage management device 14 will control the energy storage power converter 12 to reduce its power operation until the energy storage power converter 12 enters the standby state and the energy storage device 11 outputs zero power, thereby suppressing the backflow phenomenon and preventing excessive backflow of local power to the grid 20, thus achieving backflow protection.

[0032] Please see Figure 2 , Figure 2 This is a second structural block diagram of the energy storage system provided in an embodiment of this application. The energy storage system includes an energy storage device 11, an energy storage power converter 12, a grid-connected switch 13, and a reverse power protection device 16. The grid-connected switch 13, the energy storage power converter 12, and the energy storage device 11 are connected sequentially. The grid-connected switch 13 is used to connect to the power grid 20, and the reverse power protection device 16 is used to connect to the grid-connected port 15 and is connected to the grid-connected switch 13. The technical approach of the reverse power protection device 16 is as follows: when the reverse power protection device 16 detects a reverse current connection signal at the grid-connected port 15, the reverse power protection device 16 trips the grid-connected switch 13, thereby disconnecting the energy storage device 11 from the power grid 20, thus achieving reverse current protection.

[0033] Please see Figure 3 , Figure 3This is a third structural block diagram of an energy storage system provided in an embodiment of this application. The energy storage system includes an energy storage device 11, an energy storage power converter 12, a grid-connected switch 13, a reverse power protection device 16, and an anti-reverse current control device 17. The grid-connected switch 13 is used to connect to the power grid 20. The energy storage power converter 12 is connected to both the grid-connected switch 13 and the energy storage device 11. The reverse power protection device 16 is used to connect to the grid-connected port 15 and is connected to the grid-connected switch 13. The anti-reverse current control device 17 is used to connect to the grid-connected port 15 and is connected to both the reverse power protection device 16 and the energy storage power converter 12.

[0034] Unlike the energy storage system described above, the energy storage system in this embodiment is equipped with both a reverse power protection device 16 and an anti-reverse current control device 17. Based on this energy storage system, this application also provides an anti-reverse current control method, which is executed by the anti-reverse current control device 17. Please refer to... Figure 4 Specifically, the backflow prevention control method includes the following steps: S100. When the energy storage device is in a discharging state, determine whether reverse power appears at the grid connection port; S200, if so, control the energy storage power converter to gradually reduce the output power value and control the reverse power protection device to enter the lockout state, so that the grid connection switch is in the conducting state. S300: Obtain the current output power and the duration of the reverse power of the energy storage power converter, compare the duration of the reverse power with a preset time threshold, and compare the current output power with a first power threshold. S400: When the duration of reverse power is less than a preset time threshold, the reverse power protection device is controlled to maintain the locked state; when the duration of reverse power is greater than the preset time threshold and the output power is still less than the first power threshold, the reverse power protection device is controlled to exit the locked state, causing the grid-connected switch 13 to open.

[0035] When the energy storage device 11 is in a discharging state, it is first determined whether reverse power occurs at the grid connection port 15. If reverse power is detected at the grid connection port 15, the energy storage power converter 12 is controlled to gradually reduce its output power, while the reverse power protection device 16 is controlled to enter a locked state, keeping the grid connection switch 13 in a conducting state and preventing it from tripping immediately, thus ensuring uninterrupted power supply to the grid. Subsequently, the current output power of the energy storage power converter 12 and the duration of the reverse power are acquired, the duration of the reverse power is compared with a preset time threshold, and the current output power of the energy storage power converter 12 is compared with a first power threshold. If the duration of reverse power is less than the preset time threshold, it means that the reverse power disappears within the preset time threshold. In this case, the reverse power protection device 16 is kept in the locked state and does not operate. The grid-connected switch 13 is in the conducting state, and the power transmission path between the energy storage device 11 and the power grid 20 is connected. If the duration of reverse power is greater than the preset time threshold, it means that the preset time threshold has been exceeded and there is still reverse power at the grid-connected port 15. The reverse current phenomenon has not disappeared. If the current output power of the energy storage power converter 12 is still less than the first power threshold, then the protection function of the reverse power protection device 16 is triggered, and the reverse power protection device 16 is controlled to exit the locked state. The reverse power protection device 16 controls the grid-connected switch 13 to open.

[0036] Through the aforementioned hierarchical control and protection logic, when reverse power occurs at the grid connection port 15, the active suppression method of adjusting the output power of the energy storage power converter 12 is prioritized. Combined with the reverse power protection device 16, this prevents frequent malfunctions of the grid connection switch 13 due to short-term reverse power disturbances, maintaining continuous operation of the energy storage system and the grid 20, and improving the stability and continuity of the energy storage system's grid connection. Simultaneously, by combining the dual judgment conditions of reverse power duration and the output power of the energy storage power converter 12, short-term fluctuation-type reverse power and long-term abnormal-type reverse power can be accurately distinguished. In scenarios where active adjustment methods still cannot eliminate reverse power anomalies, the grid connection switch 13 is promptly triggered to disconnect, achieving dual electrical protection for both the grid 20 side and the local energy storage system. This prevents long-term reverse power from adversely affecting the operational safety of the grid 20 and related equipment, thus balancing the reliability of the energy storage system's operation with the accuracy of protection actions.

[0037] In some embodiments, after step S100, the method further includes: when no reverse power occurs at the grid connection port 15, controlling the reverse power protection device 16 to enter a locked state, so that the grid connection switch 13 is in a conducting state. When the energy storage device 11 is discharging, if it is determined by detection that no reverse power occurs at the grid connection port 15, i.e., the power flow between the local energy storage system and the grid 20 is normal, the reverse power protection device 16 is directly controlled to enter a locked state to limit the triggering logic of the reverse power protection device 16, ensuring that the grid connection switch 13 always remains in a conducting state, maintaining normal electrical connection and power interaction between the energy storage device 11 and the grid 20. In this embodiment, by actively controlling the reverse power protection device 16 to enter a locked state and keeping the grid connection switch 13 conducting, it is possible to avoid the reverse power protection device 16 being falsely triggered by ultrasonic interference signals due to small voltage fluctuations in the grid 20, and to prevent the grid connection switch from being disconnected without cause, thus ensuring the continuity and stability of the energy storage system's grid-connected operation. On the other hand, by locking the reverse power protection device 16 in advance, the reverse power protection device 16 can be put in a pre-control standby state, which does not affect the normal interaction of the system and does not require an additional protection device start-up preparation process. This is conducive to improving the overall response efficiency of the system to reverse power anomalies, and takes into account both the operational stability under normal operating conditions and the timely control under abnormal operating conditions.

[0038] In some embodiments, the anti-reverse current control method further includes: when the energy storage device 11 is in a charging state, controlling the reverse power protection device 16 to enter a locked state, so that the grid-connected switch 13 is in a conducting state. When the energy storage device 11 is in a charging state, directly controlling the reverse power protection device 16 to enter a locked state, restricting the triggering execution logic of the reverse power protection device 16 through the locked action, ensuring that the grid-connected switch 13 remains in a conducting state, maintaining the normal charging electrical connection between the energy storage device 11 and the power grid 20, ensuring that the power transmission path from the power grid 20 to the energy storage device 11 is unobstructed, and meeting the normal charging power interaction requirements of the energy storage device 11.

[0039] Please see Figure 5 In some embodiments, determining whether reverse power occurs at the gateway interface specifically includes: S110: Collect and connect the current and voltage signals output from the gateway port; S120. Calculate the real-time power based on the current and voltage signals; S130. Determine the direction of real-time power based on the preset power direction. If the direction of real-time power is positive, then confirm that no reverse power has appeared at the gate. S140. When the real-time power is reverse power, it is determined that reverse power has appeared at the gateway port.

[0040] When detecting and determining the reverse power state at the grid connection port 15, the current and voltage signals at the grid connection port 15 are first collected. Based on the collected raw current and voltage signals, the real-time power at the grid connection port 15 is calculated. Then, according to the preset power direction determination rules, the power flow direction of the real-time power is determined. If the real-time power is determined to be positive power, that is, the power flow direction conforms to the normal interaction specifications between the local system and the power grid 20, it is determined that there is no reverse power at the grid connection port 15. If the real-time power is determined to be reverse power, that is, the power flows from the local system back to the power grid 20, it is determined that there is reverse power at the grid connection port 15, thus completing the accurate detection and determination of the reverse power abnormal state. Among them, positive power refers to the power transmission state from the power grid 20 side to the local energy storage system side; reverse power refers to the power transmission state from the local energy storage system side to the power grid 20 side. The reverse power detection method in this embodiment only collects and connects the core electrical signals of the gateway port 15, without the need for additional detection equipment. While ensuring detection accuracy, it simplifies the hardware configuration of the system, reduces the hardware deployment and maintenance costs of the system, and helps to improve the overall operating efficiency of the system.

[0041] As one embodiment, step S120 specifically includes: filtering the current signal and voltage signal; and calculating the real-time power from the filtered current signal and voltage signal. In the reverse power detection process based on the grid interface 15, the current signal and voltage signal at the interface are first collected. The original collected current and voltage signals are then filtered to remove noise and interference components caused by grid fluctuations, equipment operation interference, electromagnetic noise, etc., resulting in stable and accurate filtered current and voltage signals. Based on these filtered current and voltage signals, the real-time power at the grid interface 15 is calculated using the power calculation formula, providing accurate power data for subsequent power direction determination and reverse power status identification. In this embodiment, filtering the collected signals improves the purity of the original signal and ensures the accuracy of power calculation, thereby enhancing the reliability and accuracy of reverse power detection and determination.

[0042] Please see Figure 6 , Figure 6 This is a fourth structural block diagram of an energy storage system provided in an embodiment of this application. The energy storage system includes an energy storage device 11, an energy storage power converter 12, a grid-connected switch 13, a reverse power protection device 16, a photovoltaic power generation device 18, and an anti-reverse current control device 17. The grid-connected switch 13 and the photovoltaic power generation device 18 are used to connect to the power grid 20. The energy storage power converter 12 is connected to the grid-connected switch 13 and the energy storage device 11, respectively. The reverse power protection device 16 is used to connect to the grid-connected port 15 and is connected to the grid-connected switch 13.

[0043] Unlike the energy storage systems described above, the energy storage system in this embodiment also integrates a photovoltaic (PV) power generation device 18. This PV power generation device 18 is connected to the power grid 20 and shares a grid connection interface 15, a reverse power protection device 16, and an anti-reverse current control device 17 with the energy storage device 11 and the power grid 20, forming an integrated power supply system comprising PV, energy storage, the power grid 20, and the load 30. The PV power generation device 18 can convert solar energy into alternating current, which can be preferentially supplied to the local load 30. Surplus energy can be stored in the energy storage device 11 through the energy storage power converter 12, or fed back to the power grid 20 through the grid connection interface 15 under compliant operating conditions. The working process of the PV power generation device 18 in this energy storage system is not limited in this application; it can be configured according to actual needs.

[0044] Please see Figure 7 Based on the above-described energy storage system, this application embodiment also provides an anti-backflow control method, which is executed by an anti-backflow control device 17 in the energy storage system. The anti-backflow control method specifically includes the following steps: S101. When the energy storage device is in a discharging state, determine whether reverse power appears at the grid connection port; S201. If so, control the energy storage power converter to gradually reduce the output power value and control the reverse power protection device to enter the lockout state, so that the grid-connected switch is in the conducting state. S301. The duration of the reverse power is compared with a preset time threshold, and the output power is compared with a first power threshold and a second power threshold; the second power threshold is greater than the first power threshold. S401. When the duration of reverse power is greater than or equal to a preset time threshold and the output power is greater than or equal to a second power threshold, the reverse power protection device is locked, so that the grid-connected switch remains on. S501. When the duration of reverse power is greater than or equal to a preset time threshold and the output power is less than a first power threshold, the reverse power protection device is controlled to exit the lockout state, causing the grid-connected switch to open.

[0045] When the energy storage device 11 is in discharge operation, it is first determined whether reverse power occurs at the grid connection port 15. If reverse power is detected at the grid connection port 15, the energy storage power converter 12 is controlled to gradually reduce its output power, while the reverse power protection device 16 is controlled to enter the lockout state, keeping the grid connection switch 13 in the conducting state and preventing it from tripping immediately, thus ensuring uninterrupted power supply to the grid. Subsequently, the current output power of the energy storage power converter 12 and the duration of the reverse power are acquired, and the duration of the reverse power is compared with a preset time threshold. The current output power of the energy storage power converter 12 is also compared with a first power threshold and a second power threshold. The second power threshold is greater than the first power threshold.

[0046] If the duration of reverse power is greater than or equal to a preset time threshold, it indicates that the reverse power has not disappeared after reaching the preset time threshold. However, if the current output power of the energy storage power converter 12 is greater than or equal to a second power threshold (e.g., the second power threshold is 0 and the first power threshold is -10kW), it indicates that the energy storage device 11 is not outputting power to the grid 20 side at this time. The reverse power phenomenon at the grid connection port 15 at this time may be caused by other factors (e.g., the photovoltaic power generation device 18 feeding power to the grid 20 side). Therefore, the reverse power protection device 16 is kept in the locked state, and the grid connection switch 13 remains continuously conducting. If the duration of reverse power is greater than or equal to a preset time threshold, and the current output power of the energy storage power converter 12 is less than the first power threshold, it indicates that the occurrence of reverse power is related to the energy storage device 11, thereby triggering the action conditions of the reverse power protection device 16. Therefore, the reverse power protection device 16 is controlled to exit the locked state, so that the reverse power protection device 16 triggers the grid connection switch 13 to disconnect, cutting off the electrical connection between the energy storage device 11 and the grid 20.

[0047] In this embodiment, upon detecting reverse power, the system does not directly trigger a hard protection grid disconnection. Instead, it prioritizes controlling the energy storage power converter 12 to gradually reduce its power and locks the reverse power protection device 16 to maintain grid connection. By actively adjusting the power, it attempts to resolve the reverse power, thus mitigating frequent grid disconnections caused by short-term reverse power fluctuations and improving the continuity of the energy storage system. Simultaneously, this embodiment combines the duration of reverse power and dual power thresholds to form a triple-judgment logic. This allows for the separation of reverse power causes between the energy storage and photovoltaic sides. It preserves grid-connected adjustment space for reverse power caused by photovoltaic power supply and promptly triggers protection for reverse power caused by energy storage anomalies. This approach does not affect the normal supply of photovoltaic power while achieving precise protection on the energy storage side, which is beneficial for improving the energy storage system's anti-interference capability and operational reliability under complex operating conditions such as photovoltaic output fluctuations and sudden load changes.

[0048] In some embodiments, after comparing the duration of the reverse power with a preset time threshold and comparing the output power with a first power threshold and a second power threshold, the method further includes: when the duration of the reverse power is less than the preset time threshold, controlling the reverse power protection device 16 to maintain a locked state.

[0049] When the energy storage device 11 is in discharge operation, it is first determined whether reverse power occurs at the grid connection port 15. If reverse power is detected at the grid connection port 15, the energy storage power converter 12 is controlled to gradually reduce its output power value, and the reverse power protection device 16 is controlled to enter the lockout state, keeping the grid connection switch 13 in the conducting state and temporarily not triggering the grid connection switch 13 to disconnect, thus maintaining the grid connection state between the system and the power grid 20. Subsequently, the current output power of the energy storage power converter 12 and the duration of the reverse power are obtained, and the duration of the reverse power is compared with a preset time threshold, and the current output power of the energy storage power converter 12 is compared with a first power threshold and a second power threshold. If the duration of the reverse power is less than the preset time threshold, it indicates that as the output power value of the energy storage power converter 12 decreases, the reverse power disappears within the preset time threshold. In this case, the reverse power protection device 16 can be directly controlled to maintain the lockout state, and the reverse power protection device 16 does not work. This can alleviate the frequent switching of the grid-connected switch 13 caused by short-term reverse power, ensuring continuous power interaction between the energy storage device 11, the photovoltaic power generation device 18 and the power grid 20, which is conducive to improving the continuity and stability of the entire energy storage system's grid-connected operation.

[0050] In some embodiments, the anti-reverse current control method further includes: when the energy storage device 11 is in a charging state, controlling the reverse power protection device 16 to enter a locked state, so that the grid connection switch 13 is in a conducting state. When the energy storage system is simultaneously equipped with an energy storage device 11 and a photovoltaic power generation device 18, if the energy storage device 11 is in a charging state, regardless of whether reverse power occurs at the grid connection port 15, the reverse power protection device 16 is controlled to be in a locked state, so that the reverse power protection device 16 does not malfunction, thereby alleviating the problem that the energy storage device 11 cannot be charged due to the reverse power protection device 16 malfunctioning when the photovoltaic power generation device 18 causes reverse current during the charging of the energy storage device 11.

[0051] In some embodiments, step S101 specifically includes: acquiring current and voltage signals from the parallel gateway port 15; calculating real-time power based on the current and voltage signals; determining the direction of real-time power based on a preset power direction; if the direction of real-time power is positive power, then it is determined that no reverse power has appeared at the parallel gateway port 15; if the real-time power is reverse power, then it is determined that reverse power has appeared at the parallel gateway port 15.

[0052] Similar to an energy storage system that only has energy storage device 11, the anti-reverse flow control method in this embodiment, which includes photovoltaic power generation device 18 and energy storage device 11, also involves collecting current and voltage signals at the grid connection port 15 to determine whether reverse power is present. Based on the collected raw current and voltage signals, the real-time power at the grid connection port 15 is calculated. Then, according to a preset power direction determination rule, the power flow direction of this real-time power is judged. If the real-time power is determined to be positive power, meaning the power flow direction conforms to the normal interaction specifications between the local system and the power grid 20, then it is determined that no reverse power is present at the grid connection port 15. If the real-time power is determined to be reverse power, meaning the power flows back from the local system to the power grid 20, then it is determined that reverse power is present at the grid connection port 15, thus completing the accurate detection and determination of the reverse power anomaly. The reverse power detection method in this embodiment only collects the core electrical signals of the grid connection port 15, eliminating the need for additional detection equipment. While ensuring detection accuracy, it simplifies the system's hardware configuration, reduces the system's hardware deployment and maintenance costs, and helps improve the overall operating efficiency of the system.

[0053] In the process of calculating real-time power based on current and voltage signals, the current and voltage signals can also be filtered. This can improve the purity of the original signal, ensure the accuracy of power calculation, and thus help improve the reliability and accuracy of inverse power detection and judgment.

[0054] The anti-reverse current control method of this application integrates the anti-reverse current protection logic of the energy storage management device 14 and the reverse power protection device 16, constructing a dual-device collaborative anti-reverse current protection system. This method, through hierarchical judgment, active adjustment, and linkage control of protection interlocking / triggering, effectively alleviates the technical problems of low protection timeliness and easy occurrence of actual reverse current when relying solely on the energy storage management device 14. It also avoids the problem of the independent reverse power protection device 16 uncontrollably tripping the energy storage grid connection switch 13, causing unnecessary system disconnection. Furthermore, considering the operating characteristics of the photovoltaic power generation-energy storage integrated system, by setting dual power thresholds, the cause of reverse power can be accurately distinguished, effectively alleviating the pain point of the reverse power protection device 16 malfunctioning and tripping the energy storage power station grid connection switch 13 when the energy storage device 11 is in standby state with zero output power and reverse current caused by power supply from the photovoltaic power generation device 18.

[0055] Please see Figure 8 , Figure 8This is a structural block diagram of the anti-backflow control device 17 provided in the embodiments of this application. The embodiments of this application also provide an anti-backflow control device 17, which is integrated into the aforementioned energy storage system. The anti-backflow control device 17 includes a judgment module 171, a control module 172, and a comparison module 173; the comparison module 173 is connected to both the judgment module 171 and the control module 172, and the judgment module 171 is also connected to the control module 172.

[0056] The judgment module 171 is used to determine whether reverse power occurs at the grid connection port 15 when the energy storage device 11 is in a discharging state. If reverse power occurs at the grid connection port 15, a first judgment signal is output; if reverse power does not occur at the grid connection port 15, a second judgment signal is output. The control module 172 is used to control the reverse power protection device 16 to enter a locked state according to the first and second judgment signals, so that the grid connection switch 13 is in a conducting state, and to control the energy storage power converter 12 to gradually reduce the output power value according to the first judgment signal. The comparison module 173 is used to obtain the current output power and the duration of reverse power of the energy storage power converter 12 according to the first judgment signal. If the duration of reverse power is less than a preset time threshold, a first comparison signal is output. If the duration of reverse power is greater than or equal to the preset time threshold and the output power is still less than the first power threshold, a second comparison signal is output. The control module 172 is also used to control the reverse power protection device 16 to maintain the locked state according to the first comparison signal, and to control the reverse power protection device 16 to exit the locked state according to the second comparison signal, so that the grid connection switch 13 is disconnected.

[0057] The reverse power protection device 16 in this embodiment utilizes a judgment module 171, a comparison module 173, and a control module 172. When reverse power occurs at the grid connection port 15, it prioritizes the active suppression method of adjusting the output power of the energy storage power converter 12. Combined with the blocking reverse power protection device 16, this can prevent the grid connection switch 13 from frequently malfunctioning due to short-term reverse power disturbances, maintain the continuous conduction operation of the energy storage system and the grid 20, and improve the stability and continuity of the energy storage system's grid connection operation. At the same time, by combining the dual judgment conditions of reverse power duration and the output power of the energy storage power converter 12, it can accurately distinguish between short-term fluctuation-type reverse power and long-term abnormal-type reverse power. In scenarios where active adjustment methods still cannot eliminate reverse power abnormalities, it promptly triggers the grid connection switch 13 to disconnect, achieving dual electrical protection for the grid 20 side and the local energy storage system. This prevents long-term reverse power from adversely affecting the operational safety of the grid 20 and related equipment, thus balancing the operational reliability of the energy storage system with the accuracy of protection actions.

[0058] When the aforementioned anti-reverse current control device 17 is applied to an energy storage system consisting of a photovoltaic power generation device, the comparison module 173 is used to obtain the current output power and the duration of reverse power of the energy storage power converter 12 according to the first judgment signal. When the duration of reverse power is less than a preset time threshold, the module outputs a first comparison signal. When the duration of reverse power is greater than or equal to the preset time threshold and the output power is greater than or equal to the second power threshold, the module outputs a third comparison signal. When the duration of reverse power is greater than or equal to the preset time threshold and the output power is less than the first power threshold, the module outputs a fourth comparison signal.

[0059] The control module 172 is also used to control the reverse power protection device 16 to maintain the locked state according to the first comparison signal and the third comparison signal, and to control the reverse power protection device 16 to exit the locked state according to the fourth comparison signal, so that the grid-connected switch 13 is disconnected.

[0060] In this embodiment, the anti-reverse current control device 17 utilizes a comparison module 173, a judgment module 171, and a control module 172. Upon detecting reverse power, it does not directly trigger a hard protection grid disconnection. Instead, it prioritizes controlling the energy storage power converter 12 to gradually reduce power and locks the reverse power protection device 16 to maintain grid connection. By actively adjusting the power, it attempts to eliminate reverse power, thus mitigating frequent grid disconnections caused by short-term reverse power fluctuations and improving the continuity of the energy storage system. Simultaneously, this embodiment combines the duration of reverse power and dual power thresholds to form a triple judgment logic. This allows for the separation of reverse power causes between the energy storage side and the photovoltaic side. It preserves grid-connected adjustment space for reverse power caused by photovoltaic power supply and promptly triggers protection against reverse power caused by energy storage anomalies. This approach does not affect the normal supply of photovoltaic power while achieving precise protection on the energy storage side, which is beneficial for improving the energy storage system's anti-interference capability and operational reliability under complex operating conditions such as photovoltaic output fluctuations and sudden load changes.

[0061] 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.

[0062] The anti-backflow control method, device, and energy storage system provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. 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 of the technical features. These 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 this application.

Claims

1. A method for preventing backflow control, characterized in that, The backflow prevention control method is applied to an energy storage system, which includes an energy storage device, an energy storage power converter, a grid-connected switch, and a reverse power protection device. The grid-connected switch is used to connect to the power grid. The energy storage power converter is connected to both the grid-connected switch and the energy storage device. The reverse power protection device is used to connect to the grid-connected port and is connected to the grid-connected switch. The backflow prevention control method includes the following steps: While the energy storage device is in a discharging state, determine whether reverse power appears at the parallel gateway port; If so, the energy storage power converter is controlled to gradually reduce the output power value, and the reverse power protection device is controlled to enter the lockout state, so that the grid-connected switch is in the on state; The current output power of the energy storage power converter and the duration of the reverse power are obtained, and the duration of the reverse power is compared with a preset time threshold, and the current output power is compared with a first power threshold. When the duration of the reverse power is less than a preset time threshold, the reverse power protection device is controlled to maintain the locked state; when the duration of the reverse power is greater than or equal to the preset time threshold, and the output power is still less than the first power threshold, the reverse power protection device is controlled to exit the locked state, causing the grid-connected switch to open.

2. A method for preventing backflow control, characterized in that, The anti-reverse current control method is applied to an energy storage system, which includes an energy storage device, an energy storage power converter, a grid-connected switch, a reverse power protection device, and a photovoltaic power generation device. The grid-connected switch and the photovoltaic power generation device are used for grid connection. The energy storage power converter is connected to the grid-connected switch and the energy storage device respectively. The reverse power protection device is used for grid connection and is connected to the grid-connected switch. The anti-reverse current control method includes the following steps: While the energy storage device is in a discharging state, determine whether reverse power appears at the parallel gateway port; If so, the energy storage power converter is controlled to gradually reduce the output power value, and the reverse power protection device is controlled to enter the lockout state, so that the grid-connected switch is in the on state; The duration of the reverse power is compared with a preset time threshold, and the output power is compared with a first power threshold and a second power threshold; the second power threshold is greater than the first power threshold. When the duration of the reverse power is greater than or equal to a preset time threshold and the output power is greater than or equal to the second power threshold, the reverse power protection device is controlled to be in a locked state, so that the grid-connected switch remains on. When the duration of the reverse power is greater than or equal to a preset time threshold and the output power is less than the first power threshold, the reverse power protection device is controlled to exit the lockout state, causing the grid-connected switch to disconnect.

3. The anti-backflow control method according to claim 2, characterized in that, The step of comparing the duration of the inverse power with the preset time threshold and comparing the output power with the first power threshold and the second power threshold further includes: If the duration of the reverse power is less than the preset time threshold, the reverse power protection device is controlled to maintain the locked state.

4. The anti-backflow control method according to any one of claims 1-3, characterized in that, After determining whether reverse power occurs at the parallel gateway interface when the energy storage device is in a discharging state, the process includes: When the reverse power does not appear at the grid connection port, the reverse power protection device is controlled to enter the lockout state, so that the grid connection switch is in the conducting state.

5. The anti-backflow control method according to claim 4, characterized in that, The backflow prevention control method further includes: When the energy storage device is in a charging state, the reverse power protection device is controlled to enter a locked state, so that the grid-connected switch is in a conducting state.

6. The anti-backflow control method according to claim 4, characterized in that, The specific steps for determining whether reverse power occurs at the parallel gateway interface include: Collect the current and voltage signals output from the parallel gateway. Calculate the real-time power based on the current signal and the voltage signal; The direction of the real-time power is determined based on the preset power direction. When the direction of the real-time power is positive, it is determined that no reverse power has appeared at the parallel gateway port. If the real-time power is reverse power, then it is determined that reverse power has occurred at the parallel gateway port.

7. The anti-backflow control method according to claim 6, characterized in that, The step of calculating real-time power based on the current signal and the voltage signal includes: The current signal and the voltage signal are filtered. The real-time power is calculated from the filtered current and voltage signals.

8. A backflow prevention control device, characterized in that, The backflow prevention control device includes: The judgment module is used to determine whether reverse power appears at the parallel gateway port when the energy storage device is in a discharge state, and outputs a first judgment signal when the reverse power appears at the parallel gateway port, and outputs a second judgment signal when the reverse power does not appear at the parallel gateway port. The control module is used to control the reverse power protection device to enter the lockout state according to the first judgment signal and the second judgment signal, so that the grid-connected switch is in the conducting state, and to control the energy storage power converter to gradually reduce the output power value according to the first judgment signal. The comparison module is connected to the control module and the judgment module respectively. The comparison module is used to obtain the current output power of the energy storage power converter and the duration of the reverse power according to the first judgment signal. When the duration of the reverse power is found to be less than a preset time threshold, the comparison module outputs a first comparison signal. When the duration of the reverse power is greater than or equal to the preset time threshold and the output power is still less than the first power threshold, the comparison module outputs a second comparison signal. The control module is further configured to control the reverse power protection device to maintain a locked state according to the first comparison signal, and to control the reverse power protection device to exit the locked state according to the second comparison signal, thereby causing the grid-connected switch to disconnect.

9. An energy storage system, characterized in that, The energy storage system includes an energy storage device, an energy storage power converter, a grid-connected switch, a reverse power protection device, and an anti-reverse current control device; the grid-connected switch is used to connect to the power grid; the energy storage power converter is connected to both the grid-connected switch and the energy storage device; the reverse power protection device is used to connect to the grid-connected port and is connected to the grid-connected switch; the anti-reverse current control device is used to connect to the grid-connected port and is connected to both the reverse power protection device and the energy storage power converter; the anti-reverse current control device is used to execute the anti-reverse current control method as described in claim 1.

10. An energy storage system, characterized in that, The energy storage system includes an energy storage device, an energy storage power converter, a grid-connected switch, a reverse power protection device, a photovoltaic power generation device, and an anti-reverse current control device. The grid-connected switch and the photovoltaic power generation device are used to connect to the power grid. The energy storage power converter is connected to the grid-connected switch and the energy storage device respectively. The reverse power protection device is used to connect to the grid-connected port and is connected to the grid-connected switch. The anti-reverse current control device is used to execute the anti-reverse current control method as described in claim 2.

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