Battery charging and discharging method of energy storage system and energy storage system

Abstract

The embodiment of the invention relates to the technical field of energy storage, and provides a battery charging and discharging method of an energy storage system and the energy storage system. The battery charging and discharging method of the energy storage system comprises the following steps: monitoring a single battery voltage and a battery total voltage; under the condition that the voltage of the single battery meets a first preset condition, a first multi-stage protection strategy is started, and the strategy comprises that different charging and discharging protection measures are taken when the voltage of the single battery reaches different preset values; under the condition that the total voltage of the battery meets a second preset condition, a second multi-stage protection strategy is started, and according to the strategy, different charging and discharging protection measures are taken when the total voltage of the battery reaches different preset values. According to the technical scheme, the problem that in the prior art, an overvoltage protection mechanism is single, refined protection cannot be provided according to different voltage levels, and consequently the safety of an energy storage system is insufficient can be effectively solved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery charging and discharging method and an energy storage system. Background Art

[0002] Overvoltage protection is an important component of energy storage system safety, used to prevent battery damage or safety incidents caused by excessive voltage.

[0003] Current energy storage converters are generally equipped with overvoltage protection mechanisms to prevent battery overcharging. However, these mechanisms are typically triggered by a single threshold. Once the battery voltage reaches a preset overvoltage protection point, immediate action is taken, such as stopping charging. While this provides basic safety protection, it has certain limitations in practical applications. Specifically, a single overvoltage protection point cannot fully account for the differences between different battery systems and operating environments. For example, in a low-temperature environment, the upper limit of the battery's charging voltage may be higher than that in a normal temperature environment. A single overvoltage protection point may lead to premature charging interruption, thereby affecting battery charging efficiency and the performance of the entire energy storage system. Summary of the Invention

[0004] The embodiments of the present application provide a battery charging and discharging method and an energy storage system for an energy storage system, which at least solves the problem in the prior art that the overvoltage protection mechanism is single and cannot provide refined protection according to different voltage levels, thereby resulting in insufficient safety of the energy storage system.

[0005] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a battery charging and discharging method for an energy storage system, including: monitoring the voltage of a single cell and the total voltage of the battery; when the voltage of the single cell meets a first preset condition, starting a first multi-level protection strategy, the first multi-level protection strategy including adopting different charging and discharging protection strategies when the voltage of the single cell reaches different preset single cell voltages; when the total voltage of the battery meets a second preset condition, starting a second multi-level protection strategy, the second multi-level protection strategy including adopting different charging and discharging protection strategies when the total voltage of the battery reaches different preset total pressures.

[0006] In some embodiments, when the single cell voltage satisfies the first preset condition, before starting the first multi-stage protection strategy, the method further includes: when the single cell voltage reaches any of the preset single cell voltages and maintains the voltage for a corresponding period of time, determining that the single cell voltage satisfies the first preset condition; when the battery total voltage satisfies the second preset condition, before starting the second multi-stage protection strategy, the method further includes: when the battery total voltage reaches any of the preset total voltages and maintains the voltage for a corresponding period of time, determining that the battery total voltage satisfies the second preset condition.

[0007] In some embodiments, the first multi-level protection strategy includes a first sub-protection strategy, a second sub-protection strategy, and a third sub-protection strategy. When the single cell voltage meets a first preset condition, the first multi-level protection strategy is activated, including: when the single cell voltage reaches a first preset single cell voltage and maintains for a first time period, the first sub-protection strategy is activated, and the first sub-protection strategy is used to control the PCS charge and discharge power to drop to a first charge and discharge power; when the single cell voltage reaches a second preset single cell voltage and maintains for a second time period, the second sub-protection strategy is activated, and the second sub-protection strategy is used to control the PCS charge and discharge power to drop to a second charge and discharge power; when the single cell voltage reaches a third preset single cell voltage and maintains for a third time period, the third sub-protection strategy is activated, and the third sub-protection strategy is used to control the PCS charge and discharge power to drop to a third charge and discharge power; wherein the first preset single cell voltage is less than the second preset single cell voltage, the second preset single cell voltage is less than the third preset single cell voltage, the first time period is greater than the second time period, the second time period is greater than the third time period, the first charge and discharge power is greater than the second charge and discharge power, and the second charge and discharge power is greater than the third charge and discharge power.

[0008] In some embodiments, the second multi-level protection strategy includes a fourth sub-protection strategy, a fifth sub-protection strategy, and a sixth sub-protection strategy. When the battery total voltage meets the second preset condition, the second multi-level protection strategy is activated, including: when the battery total voltage reaches a first preset total voltage and is maintained for a fourth time period, the fourth sub-protection strategy is activated, and the fourth sub-protection strategy is used to control the PCS charge and discharge power to drop to a fourth charge and discharge power; when the single cell voltage reaches a second preset total voltage and is maintained for a fifth time period, the fifth sub-protection strategy is activated, and the fifth sub-protection strategy is used to control the PCS charge and discharge power to drop to a fifth charge and discharge power; when the single cell voltage reaches a third preset total voltage and is maintained for a sixth time period, the sixth sub-protection strategy is activated, and the sixth sub-protection strategy is used to control the PCS charge and discharge power to drop to a sixth charge and discharge power; wherein the first preset total voltage is less than the second preset total voltage, the second preset total voltage is less than the third preset total voltage, the fourth time period is greater than the fifth time period, the fifth time period is greater than the sixth time period, the fourth charge and discharge power is greater than the fifth charge and discharge power, and the fifth charge and discharge power is greater than the sixth charge and discharge power.

[0009] In some embodiments, when the single cell voltage meets a first preset condition, a first multi-level protection strategy is initiated, including: when the single cell voltage meets the first preset condition, one of an alarm strategy, a charge and discharge prohibition strategy, and a high-voltage power-off strategy is initiated, wherein the alarm strategy is to adjust the PCS to enter a constant voltage charging mode, the charge and discharge prohibition strategy is to limit the PCS charge and discharge power, and the high-voltage power-off strategy is to reduce the PCS charge and discharge power to zero.

[0010] In some embodiments, the method further includes: predicting the predicted single cell voltage and the predicted total battery voltage at a future target time point based on the single cell voltage and the total battery voltage obtained in the current time period; starting a first pre-protection strategy based on the predicted single cell voltage, the first pre-protection strategy including at least one of pre-reducing the PCS charging and discharging power, pre-enhancing cooling, and optimizing load charging distribution; starting a second pre-protection strategy based on the predicted single cell voltage, the second pre-protection strategy including at least one of pre-reducing the PCS charging and discharging power, pre-cutting off the charging branch, and pre-fault isolation.

[0011] According to some embodiments of the present application, another aspect of the present application provides an energy storage system, comprising: a plurality of battery clusters, each of the battery clusters comprising a plurality of single cells connected in series; a plurality of battery management units electrically connected to the single cells in a one-to-one correspondence; a plurality of battery control units, one of the battery control units being connected to the plurality of battery management units via a bus, the number of the battery control units being equal to the number of the battery clusters; a network switch and a system control unit, each of the battery control units being connected to the network switch via a bus, and the network switch being connected to the system control unit via a bus; an energy storage converter being connected to the system control unit via a bus, and having a charging branch connected to the single cells; wherein the battery management units are configured to obtain single cell voltages, the battery control unit is configured to activate a first multi-stage protection strategy when the single cell voltage meets a first preset condition, the first multi-stage protection strategy including adopting different charge and discharge protection strategies when the single cell voltage reaches different preset single cell voltages, and the energy storage converter is configured to monitor the total battery voltage and to activate a second multi-stage protection strategy when the total battery voltage meets a second preset condition, the second multi-stage protection strategy including adopting different charge and discharge protection strategies when the total battery voltage reaches different preset total voltages.

[0012] According to some embodiments of the present application, the energy storage system further includes: an energy management system connected to the system control unit via a bus.

[0013] According to some embodiments of the present application, the energy storage system further includes: a plurality of high-voltage boxes, wherein one of the high-voltage boxes includes a battery control unit and a charging branch.

[0014] According to some embodiments of the present application, another aspect of the embodiments of the present application provides an energy storage system, comprising: multiple battery clusters, each of the battery clusters comprising multiple single cells connected in series; multiple battery management units, electrically connected to the single cells in a one-to-one correspondence; multiple energy storage converters, each of the energy storage converters comprising a battery control unit, a charging branch, and an auxiliary control unit, one battery control unit being connected to multiple battery management units via a bus, and the number of battery control units being equal to the number of battery clusters; a network switch and a system control unit, each of the energy storage converters being connected to the network switch via a bus, and the network switch being connected to the system control unit via a bus; wherein the battery management unit is configured to obtain a single cell voltage, the battery control unit is configured to activate a first multi-stage protection strategy when the single cell voltage meets a first preset condition, the first multi-stage protection strategy including adopting different charge and discharge protection strategies when the single cell voltage reaches different preset single cell voltages, and the auxiliary control unit is configured to monitor the battery total voltage and, when the battery total voltage meets a second preset condition, activate a second multi-stage protection strategy including adopting different charge and discharge protection strategies when the battery total voltage reaches different preset total voltages.

[0015] According to some embodiments of the present application, the energy storage system further includes: an energy management system connected to the system control unit via a bus.

[0016] According to some embodiments of the present application, the energy storage system further includes: multiple battery cabinets, the number of the battery cabinets being equal to the number of the battery clusters; wherein, one of the battery clusters, one of the energy storage inverters, the network switch, and the system control unit are integrated in a target battery cabinet, the target battery cabinet is one of the multiple battery cabinets, and one of the battery clusters and the energy storage inverter is integrated in a non-target battery cabinet.

[0017] According to some embodiments of the present application, the energy storage converter further includes: a DCAC converter electrically connected to the charging branch.

[0018] According to some embodiments of the present application, one of the charging branches includes: a circuit breaker, a contactor module and a fuse connected in series, one end of the circuit breaker is electrically connected to the single battery, and one end of the fuse is electrically connected to one end of the DCAC converter.

[0019] According to some embodiments of the present application, the energy storage system further includes: a dehumidifier, a liquid cooler, a temperature and humidity sensor, and a water immersion sensor, which respectively communicate with the battery control unit via a bus.

[0020] The technical solutions provided by the embodiments of the present application have at least the following advantages: They monitor not only the voltage of individual cells, i.e., individual cell voltages, but also the total voltage of the entire battery pack, and initiate corresponding multi-level protection strategies based on the monitoring results. This comprehensive monitoring approach ensures comprehensive protection from the microscopic individual cells to the macroscopic overall battery pack, improving system safety and reliability. Setting different preset cell voltages and total voltages fully accounts for the differences between different battery systems and operating environments. The first and second multi-level protection strategies employ different levels of charge and discharge protection measures based on voltage levels. This means that the more severe the overvoltage condition, the more stringent the system protection measures. This graded response effectively avoids resource waste caused by overprotection while ensuring that the system can respond quickly when emergency intervention is truly necessary, thus preventing major accidents. By dynamically adjusting the charge and discharge strategies, battery safety can be maintained while preserving the performance and service life of the battery pack to the greatest extent possible. This set of protection measures, implemented at the earliest stages of an overvoltage event, provides early warning of a fault, allowing the system to intervene before a minor problem develops, preventing it from escalating. Through preventative protection measures, the system can reduce battery failure rates, extend the service life of the battery pack, and reduce maintenance costs. It can effectively solve the problem in the existing technology that the overvoltage protection mechanism is single and cannot provide refined protection according to different voltage levels, thus leading to insufficient safety of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] One or more embodiments are exemplified by the figures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic flow chart of a battery charging and discharging method for an energy storage system provided in an embodiment of the present application;

[0023] Figure 2 A schematic diagram of a battery charging and discharging method for a specific energy storage system provided in an embodiment of the present application;

[0024] Figure 3A schematic diagram of another specific battery charging and discharging method for an energy storage system provided in an embodiment of the present application;

[0025] Figure 4 A schematic diagram of an energy storage system provided in an embodiment of the present application;

[0026] Figure 5 Schematic diagram of another energy storage system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] As can be seen from the background art, a single overvoltage protection point cannot fully account for the differences between different battery systems and operating environments. To address this issue, embodiments of the present application provide a battery charging and discharging method and energy storage system for an energy storage system.

[0028] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0029] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0031] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0032] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0033] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0034] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) as being on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present between the two components. Conversely, when describing a component as being on the surface of another component or as being formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0035] In the description of the embodiments of this application, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them) or another component can be present between them. In addition, when a component such as a layer, film, region, or plate is "directly on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located between them.

[0036] The terms used herein in the description of the various embodiments are intended only to describe the specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "part" is intended to include the plural form unless the context clearly indicates otherwise. A component includes a layer, film, region, or plate.

[0037] The following detailed description of the various embodiments of the present application is provided in conjunction with the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present application to facilitate a better understanding of the present application. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0038] The embodiment of the present application provides a battery charging and discharging method for an energy storage system, Figure 1 Flowchart of the battery charging and discharging method of the energy storage system according to the embodiment of the present application. Figure 1 As shown, the method includes the following steps:

[0039] Step S101, monitoring the single cell voltage and the total battery voltage;

[0040] A battery cluster or battery pack is composed of multiple single cells connected in series or in parallel. The single cell voltage refers to the voltage of the single cell, and the total battery voltage refers to the voltage of the entire battery pack.

[0041] Step S102, when the single cell voltage meets a first preset condition, starting a first multi-stage protection strategy, wherein the first multi-stage protection strategy includes adopting different charge and discharge protection strategies when the single cell voltage reaches different preset single cell voltages;

[0042] Once the monitored cell voltage meets the first pre-set condition, a multi-level protection strategy is activated. This provides different levels of protection response based on the severity of the overvoltage condition. This multi-level strategy means that the protection mechanism is not a one-size-fits-all approach, but rather gradually escalates based on the severity of the overvoltage, resulting in a more precise and effective response.

[0043] Step S103 , when the battery total pressure meets a second preset condition, starting a second multi-stage protection strategy, wherein the second multi-stage protection strategy includes adopting different charge and discharge protection strategies when the battery total pressure reaches different preset total pressures.

[0044] That is, when the total pressure meets the second pre-set condition, the most stringent measures are not immediately taken. Instead, the protection strategy is implemented gradually according to the total pressure level. This multi-level strategy allows for more precise control of the response, avoiding excessive protection measures when the problem is not serious, which would affect the normal use and efficiency of the battery pack.

[0045] It should be noted that the solution including S101, S102 and S103 of the present application can be applied not only in the battery charging process but also in the battery discharging process.

[0046] Through steps S101, S102, and S103, not only the voltage of the individual cells (i.e., individual cell voltages) but also the total voltage of the entire battery pack are monitored. Based on the monitoring results, the corresponding multi-level protection strategy is activated. This comprehensive monitoring approach ensures comprehensive protection from the microscopic individual cells to the macroscopic overall battery pack, improving system safety and reliability. Setting different preset cell voltages and total voltages fully accounts for the differences between different battery systems and operating environments. The first and second multi-level protection strategies employ different levels of charge and discharge protection measures based on voltage levels. This means that the more severe the overvoltage condition, the more stringent the system protection measures. This graded response effectively avoids resource waste caused by overprotection while ensuring that the system can respond quickly when emergency intervention is truly necessary, thus preventing major accidents. By dynamically adjusting the charge and discharge strategy, battery safety is ensured while preserving the performance and service life of the battery pack to the greatest extent possible. This set of protection measures, implemented at the earliest stages of an overvoltage event, provides early warning of a fault, allowing the system to intervene before a minor problem develops, preventing it from escalating. Through preventative protection measures, the system can reduce battery failure rates, extend the service life of the battery pack, and reduce maintenance costs. It can effectively solve the problem in the existing technology that the overvoltage protection mechanism is single and cannot provide refined protection according to different voltage levels, thus leading to insufficient safety of the energy storage system.

[0047] In a specific implementation, when the single cell voltage satisfies the first preset condition, before initiating the first multi-stage protection strategy, the method further includes: when the single cell voltage reaches any of the preset single cell voltages and maintains the voltage for a corresponding period of time, determining that the single cell voltage satisfies the first preset condition;

[0048] By monitoring individual cell voltages and setting different preset cell voltage thresholds, the system can react promptly when the battery voltage begins to approach unsafe levels. More importantly, by requiring the voltage to remain above the preset threshold for a certain period of time before triggering protection, false alarms caused by transient voltage fluctuations are effectively avoided, improving the accuracy and stability of overvoltage detection.

[0049] Some overvoltage protection solutions trigger protection immediately when the voltage first exceeds the threshold. While this approach provides a quick response, it can lead to unnecessary battery usage restrictions in some cases. This solution sets a maintenance time, allowing the system to intelligently determine whether an overvoltage condition truly requires intervention, thereby minimizing the impact on normal battery operation while ensuring safety.

[0050] By adopting different degrees of charge and discharge protection strategies under different preset single-cell voltages, the battery's charge and discharge process can be controlled more precisely, avoiding the impact of sudden and drastic changes in charging current or power on the battery, protecting the battery's health and extending the battery's service life.

[0051] See Figure 2 During the battery charging process, if the single cell voltage rises to 3550mV and maintains for 185s, it means the single cell voltage is overvoltage level 1; if the single cell voltage rises to 3600mV and maintains for 25s, it means the single cell voltage is overvoltage level 2; if the single cell voltage rises to 3630mV and maintains for 12s, it means the single cell voltage is overvoltage level 3.

[0052] See Figure 3 During the battery discharge process, if the single cell voltage drops to 2850mV and maintains for 12s, it means the single cell voltage is overvoltage level 3; if the single cell voltage drops to 2800mV and maintains for 25s, it means the single cell voltage is overvoltage level 2; if the single cell voltage drops to 2550mV and maintains for 185s, it means the single cell voltage is overvoltage level 1.

[0053] When the above-mentioned total battery voltage meets the second preset condition, before starting the second multi-level protection strategy, the above-mentioned method also includes: when the above-mentioned total battery voltage reaches any of the above-mentioned preset total pressures and maintains the corresponding time, determining that the above-mentioned total battery voltage meets the above-mentioned second preset condition.

[0054] By setting the battery total voltage to maintain a preset total voltage for a certain period of time before triggering protection, false alarms caused by measurement noise or brief voltage fluctuations can be avoided. This ensures that overvoltage protection is accurately triggered when there is a real overvoltage risk, enhancing the stability and accuracy of the protection logic.

[0055] During battery total voltage monitoring, transient voltage spikes may occur. Without a time limit, these spikes could erroneously trigger protection mechanisms, impacting the normal operation of the energy storage system. By increasing the hold time requirement, the system can eliminate interference from brief peaks and respond only to sustained overvoltage conditions, improving intelligent decision-making capabilities.

[0056] This added condition before initiating the second multi-level protection strategy means that further protection measures will only be taken if the total battery voltage exceeds the preset threshold and remains at that level for a certain period of time. This ensures that the triggering of the protection strategy is necessary, avoids unnecessary system interruptions, and makes the protection measures more targeted and effective.

[0057] See Figure 2 During the battery charging process, the total battery voltage rises to 923V and maintains for 65s, which means the total voltage is overvoltage level one; the total battery voltage rises to 936V and maintains for 25s, which means the total voltage is overvoltage level two; the total battery voltage rises to 943.8V and maintains for 12s, which means the total voltage is overvoltage level three.

[0058] See Figure 3 During the battery discharge process, if the total battery voltage drops to 741V and maintains for 12s, it means the total voltage is overvoltage level 3; if the total battery voltage drops to 728V and maintains for 25s, it means the total voltage is overvoltage level 2; if the total battery voltage drops to 663V and maintains for 65s, it means the total voltage is overvoltage level 1.

[0059] In the embodiment of the present application, the first multi-level protection strategy includes a first sub-protection strategy, a second sub-protection strategy, and a third sub-protection strategy. When the voltage of the single battery cell meets the first preset condition, the first multi-level protection strategy is activated, including:

[0060] When the single cell voltage reaches a first preset single cell voltage and maintains for a first time period, a first sub-protection strategy is activated, wherein the first sub-protection strategy controls the PCS charge and discharge power to drop to a first charge and discharge power;

[0061] See Figure 2 , the single cell voltage rises to 3550mV and maintains for 185s, which means the single cell voltage is overvoltage level 1, and the first sub-protection strategy is activated;

[0062] See Figure 3 , the single cell voltage drops to 2550mV and maintains it for 185s, which means the single cell voltage is overvoltage level 1, and the first sub-protection strategy is activated;

[0063] When the single cell voltage reaches a second preset single cell voltage and maintains for a second time period, a second sub-protection strategy is activated, wherein the second sub-protection strategy controls the PCS charge and discharge power to drop to a second charge and discharge power;

[0064] See Figure 2 ,When the single cell voltage rises to 3600mV and maintains for 25s, it means that the single cell voltage is overvoltage level 2, and the second sub-protection strategy is activated;

[0065] See Figure 3, the single cell voltage drops to 2800mV and maintains for 25s, which means the single cell voltage is overvoltage level 2, and the second sub-protection strategy is activated;

[0066] When the single cell voltage reaches a third preset single cell voltage and maintains for a third time period, a third sub-protection strategy is activated, wherein the third sub-protection strategy controls the PCS charge and discharge power to drop to a third charge and discharge power;

[0067] See Figure 2 , the single cell voltage rises to 3630mV and maintains for 12s, which means that the single cell voltage is overvoltage level 3, and the third sub-protection strategy is activated.

[0068] See Figure 3 , the single cell voltage drops to 2850mV and maintains for 12s, which means that the single cell voltage is overvoltage level 3, and the third sub-protection strategy is activated.

[0069] Among them, the above-mentioned first preset single cell voltage is less than the above-mentioned second preset single cell voltage, the above-mentioned second preset single cell voltage is less than the third preset single cell voltage, the above-mentioned first time length is greater than the above-mentioned second time length, the above-mentioned second time length is greater than the above-mentioned third time length, the above-mentioned first charge and discharge power is greater than the above-mentioned second charge and discharge power, and the above-mentioned second charge and discharge power is greater than the above-mentioned third charge and discharge power.

[0070] The above-mentioned first multi-level protection strategy includes a first sub-protection strategy, a second sub-protection strategy, and a third sub-protection strategy, and its technical effects are:

[0071] By setting three different cell voltage thresholds (first, second, and third preset cell voltages) and corresponding charge and discharge power reduction levels (first, second, and third charge and discharge power), the system can gradually reduce the PCS charge and discharge power based on changes in battery voltage, rather than a sudden, all-at-once reduction. This approach effectively avoids the impact of instantaneous power changes when the battery is overvoltage, protecting the battery from damage.

[0072] During charging, when the cell voltage reaches a preset condition, the system first activates the lighter first sub-protection strategy. Only after the voltage rises further and remains constant for a period of time does the system sequentially activate the more stringent second and third sub-protection strategies. This sequential control allows the battery to operate within a safe range for as long as possible, balancing overvoltage protection with battery performance.

[0073] During the discharge process, the voltage of the single cell gradually decreases, so the activation order is the third sub-protection strategy, the second sub-protection strategy, and the first sub-protection strategy. During the discharge process, the charge and discharge power restrictions are gradually relaxed, allowing the battery to continue to operate under more relaxed discharge conditions at a lower voltage. This can reduce excessive stress on the battery in the low voltage range, thereby extending the overall life of the battery and improving the economic benefits of the energy storage system. When the battery voltage drops to the corresponding threshold, the system can quickly identify and activate the corresponding sub-protection strategy. This immediate response mechanism can effectively control the battery discharge rate, avoid system performance degradation caused by excessive discharge, and improve the stability and reliability of the energy storage system. During the battery discharge stage, through gradual power adjustment, the energy stored in the battery can be more fully utilized. In particular, when the battery voltage is close to the minimum safety threshold, the first sub-protection strategy allows a lower but controllable discharge power, which can maximize energy recovery and reduce energy waste.

[0074] The activation conditions (preset cell voltage and duration) of each sub-protection strategy are carefully designed to ensure timely adjustment of the PCS charge and discharge power when the battery is close to overcharge, preventing the battery voltage from exceeding the safe range, effectively preventing overcharging and protecting the safety and life of the battery.

[0075] The first multi-level protection strategy automatically adjusts based on the real-time status of the battery, without the need for manual intervention, providing instant and intelligent overvoltage protection. This response is faster than traditional manual adjustment or single threshold triggering, improving the automation level and operational efficiency of the energy storage system.

[0076] By gradually adjusting the charge and discharge power of the PCS rather than simply stopping it, the system can protect the battery while avoiding unnecessary energy waste, reducing energy consumption and optimizing the overall management of the energy storage system.

[0077] A reasonable charge and discharge power adjustment strategy helps reduce the operating time and frequency of the battery under extreme voltage conditions, thereby reducing battery stress, extending the battery cycle life, and improving the economy of the energy storage system in the long run.

[0078] The multi-level protection strategy increases the system's safety redundancy through multi-level voltage monitoring and power adjustment. Even if one level of protection fails, subsequent protection strategies can still work, effectively avoiding systemic risks that may be caused by battery overvoltage.

[0079] In summary, the adoption of a multi-level hierarchical protection strategy can take corresponding measures according to the different stages of battery voltage. This not only protects the safe operation of the battery and avoids the risks of overcharging and over-discharging, but also takes into account the performance and economy of the energy storage system. It embodies the design concept of intelligence, efficiency and safety, and is an important innovation in energy storage technology in the field of battery management.

[0080] It should be noted that the first multi-level protection strategy including the first sub-protection strategy, the second sub-protection strategy and the third sub-protection strategy is only an exemplary solution. The division of more or fewer sub-protection strategies based on actual needs falls within the protection concept of this application.

[0081] In a specific implementation, the second multi-level protection strategy includes a fourth sub-protection strategy, a fifth sub-protection strategy, and a sixth sub-protection strategy. When the total battery voltage meets the second preset condition, the second multi-level protection strategy is activated, including:

[0082] When the battery total voltage reaches the first preset total voltage and is maintained for a fourth time period, a fourth sub-protection strategy is activated, wherein the fourth sub-protection strategy controls the PCS charge and discharge power to decrease to a fourth charge and discharge power;

[0083] See Figure 2 , the total battery voltage rises to 923V and remains for 65s, which means the total voltage is overvoltage level 1, and the fourth sub-protection strategy is activated;

[0084] See Figure 3 , the total battery voltage dropped to 663V and maintained for 65s, which means the single cell voltage is overvoltage level 1, and the fourth sub-protection strategy is activated;

[0085] When the single cell voltage reaches the second preset total voltage and maintains for a fifth time period, a fifth sub-protection strategy is activated, wherein the fifth sub-protection strategy controls the PCS charge and discharge power to drop to a fifth charge and discharge power;

[0086] See Figure 2 , the total battery voltage rises to 936V and remains for 25s, which means the total voltage is overvoltage level 2, and the fifth sub-protection strategy is activated;

[0087] See Figure 3 , the total battery voltage drops to 728V and remains for 25s, which means the total voltage is overvoltage level 2, and the fifth sub-protection strategy is activated;

[0088] When the single cell voltage reaches the third preset total voltage and is maintained for a sixth time period, a sixth sub-protection strategy is activated, wherein the sixth sub-protection strategy controls the PCS charge and discharge power to decrease to a sixth charge and discharge power;

[0089] See Figure 2The total battery voltage rises to 943.8V and remains for 12 seconds, which means the total voltage is overvoltage level 3, and the sixth sub-protection strategy is activated;

[0090] See Figure 3 , the total battery voltage dropped to 741V and maintained for 12s, which means that the single cell voltage is overvoltage level 3, and the sixth sub-protection strategy is activated;

[0091] Among them, the above-mentioned first preset total pressure is less than the above-mentioned second preset total pressure, the above-mentioned second preset total pressure is less than the third preset total pressure, the above-mentioned fourth time length is greater than the above-mentioned fifth time length, the above-mentioned fifth time length is greater than the above-mentioned sixth time length, the above-mentioned fourth charge and discharge power is greater than the above-mentioned fifth charge and discharge power, and the above-mentioned fifth charge and discharge power is greater than the above-mentioned sixth charge and discharge power.

[0092] The above-mentioned second multi-level protection strategy, including the fourth sub-protection strategy, the fifth sub-protection strategy, and the sixth sub-protection strategy, has the following key technical effects:

[0093] By setting three increasing battery total voltage thresholds (the first, second, and third preset total voltages) and sequentially activating different levels of sub-protection strategies according to the increase in battery total voltage, overvoltage protection is achieved at the system level, ensuring the safe operation of the energy storage system under high-voltage conditions.

[0094] Each sub-protection strategy controls the PCS charge and discharge power to gradually decrease to a lower level (the fourth, fifth, and sixth charge and discharge power), avoiding a sudden and sharp drop in charge and discharge power when the total voltage is too high, thereby reducing the impact on the battery and PCS, ensuring a smooth transition of the system and continued stability of battery performance.

[0095] Each sub-protection strategy is set to maintain a certain duration before activation (the fourth, fifth, and sixth durations). This time buffering mechanism not only effectively filters the impact of instantaneous voltage fluctuations and avoids false activation of protection strategies, but also provides the system with sufficient response time for more accurate power adjustment and fault diagnosis.

[0096] When the total battery voltage rises abnormally, the system can quickly identify and initiate the corresponding sub-protection strategy. By gradually reducing the charge and discharge power, it provides conditions for timely response to faults and safe recovery of the system, reducing system failures or downtime caused by excessive total voltage.

[0097] An increase in the total battery voltage is usually accompanied by an increase in the internal battery temperature. By promptly initiating a sub-protection strategy to reduce the charge and discharge power, the heating of the battery can be effectively controlled, the thermal management of the energy storage system can be optimized, and the battery performance degradation and safety hazards caused by excessive temperature can be avoided.

[0098] The multi-level protection strategy allows the system to attempt to alleviate the situation through gentle power adjustments when the total battery voltage increases, and only take more stringent measures when necessary. This strategy balances cost control and performance protection, avoiding the increased energy consumption and reduced system efficiency caused by over-protection.

[0099] The second multi-level protection strategy provides a system-level overvoltage protection solution, which enhances the robustness of the energy storage system. Even under extreme operating conditions, it can effectively protect the battery from overvoltage damage, ensuring the stability of the system and the reliability of long-term operation.

[0100] In summary, the second multi-level protection strategy effectively addresses abnormal increases in battery total voltage by controlling the PCS's charge and discharge power in stages and steps. This not only ensures the safe operation of the energy storage system but also maximizes its performance and economic value. It has significant innovative significance and application value in the field of energy storage technology.

[0101] The fourth duration is greater than the fifth duration, and the fifth duration is greater than the sixth duration. Specifically, the fourth duration, the fifth duration, and the sixth duration may be determined in the following manner:

[0102] First, the setting of these time thresholds must take into account the inherent characteristics of the battery, such as the battery's charge and discharge rates, the rate of voltage rise, and the battery's safe operating range at different voltages. Battery safety standards and industry regulations also guide the setting of time thresholds, ensuring that protective measures are taken in a timely manner in the event of overvoltage without causing damage to the battery.

[0103] These time thresholds are also related to the energy storage system's response speed to overvoltage conditions. For example, 65 seconds can be considered a buffer period, giving the system ample time to detect overvoltage and implement primary protection strategies. However, 25 seconds and 12 seconds represent the time windows within which the system must more quickly implement secondary and tertiary protection strategies to prevent more severe overvoltage conditions.

[0104] The determination of the time threshold is usually based on risk assessment and extensive experimental verification.

[0105] Analyzing the battery's specific performance under overvoltage conditions based on historical operating data, including the rate of voltage rise and the duration of the overvoltage state, can help determine a reasonable threshold. For example, if historical data shows that after the battery voltage reaches 923V, it typically recovers automatically or reduces the voltage through other mechanisms within 65 seconds, then 65 seconds can be considered a reasonable trigger time for Level 1 protection.

[0106] Battery models can also be used for simulation and evaluation to assess battery behavior under different voltage and time conditions. These simulation results can be used to optimize the timing thresholds to ensure effective overvoltage protection in real-world applications.

[0107] Therefore, repeated testing and optimization are conducted through experiments, simulations, and data analysis to ensure that the energy storage system provides the most appropriate protection response under different overvoltage levels, while also balancing system operational efficiency and safety. In actual applications, these time thresholds may also be dynamically adjusted based on the specific system operating conditions and battery status. Similarly, the first, second, and third durations can also be determined using the above scheme.

[0108] It should be noted that the second multi-level protection strategy including the fourth sub-protection strategy, the fifth sub-protection strategy and the sixth sub-protection strategy is only an exemplary solution. The division of more or fewer sub-protection strategies based on actual needs falls within the protection concept of this application.

[0109] See also Figure 2 During charging, total voltage overvoltage occurs after individual cells overvoltage. Therefore, individual cells can be monitored first, followed by total voltage. Since total voltage overvoltage typically occurs after multiple individual cells overvoltage, monitoring individual cells first reduces the system's response time from overvoltage detection to protective measures. This timely response effectively controls the rising trend of battery voltage, preventing the battery from entering an overvoltage state and ensuring stable system operation. Early monitoring of individual cells allows the system to adjust charging strategies based on specific battery conditions, such as slowing the charging rate and optimizing the charging sequence, thereby achieving more refined battery management. This strategy optimization helps extend battery life and improve the performance and cost-effectiveness of the energy storage system. Early detection of individual cell overvoltage allows timely measures to prevent total voltage overvoltage, reducing the need for large-scale system maintenance or battery replacement due to such events, reducing maintenance costs, and improving the operational efficiency of the energy storage system. Monitoring individual cell voltage first, followed by total voltage, allows for earlier measures to prevent overvoltage conditions, thereby improving the safety of the entire energy storage system. Even in extreme cases, the system can avoid dangerous events such as battery thermal runaway and explosion through early warning and intervention.

[0110] See also Figure 3During discharge, total voltage overvoltage occurs before individual cell overvoltage. Therefore, during discharge, the total voltage can be monitored first, followed by individual cell voltage. If the total voltage is not overvoltage during discharge, the system does not need to further examine the individual cell level. This not only saves monitoring resources but also reduces unnecessary data processing and analysis, improving system efficiency. Although total voltage overvoltage occurs before individual cell overvoltage, this does not mean that the individual cell status is unimportant. On the contrary, total voltage overvoltage is often caused by the individual cell status. Therefore, monitoring total voltage first and then individual cells as necessary can help the system predict and prevent potential failures earlier, allowing appropriate measures to avoid system-level overvoltage events. During discharge, total voltage overvoltage may indicate an impending major safety threat to the system, such as battery thermal runaway or fire. By promptly detecting total voltage and taking swift action, the system can contain the situation before it escalates, significantly improving the safety and stability of the energy storage device. While ensuring that the total voltage does not overvoltage, the system can also optimize the cell balancing strategy by monitoring individual cell voltages. Maintaining balance among individual cells within the battery pack during discharge helps improve the overall performance and service life of the battery pack.

[0111] In some embodiments, when the voltage of the single battery cell satisfies a first preset condition, activating a first multi-level protection strategy includes:

[0112] When the voltage of the above-mentioned single battery meets the first preset condition, one of the alarm strategy, the charge and discharge prohibition strategy and the high-voltage power-off strategy is activated, wherein the above-mentioned alarm strategy is to adjust the PCS to enter the constant voltage charging mode, the above-mentioned charge and discharge prohibition strategy is to limit the PCS charge and discharge power, and the above-mentioned high-voltage power-off strategy is to reduce the PCS charge and discharge power to zero.

[0113] As described above, the single cell voltage corresponding to the warning strategy, the charge and discharge prohibition strategy, and the high-voltage power-off strategy gradually increases.

[0114] When the single cell voltage meets the first preset condition, one of the alarm strategy, the charge and discharge prohibition strategy, and the high-voltage power-off strategy is activated, and the single cell voltage corresponding to these strategies gradually increases. The technical effects of this design are mainly reflected in the following aspects:

[0115] The alarm strategy is activated when the battery voltage just exceeds the normal range. By adjusting the PCS to enter constant voltage charging mode, it can effectively reduce the further increase of the battery voltage, playing a preventive protection role and preventing the battery voltage from unnecessarily approaching a more dangerous threshold.

[0116] As the battery voltage rises, the system first initiates a milder warning strategy, then upgrades to a charge / discharge restriction strategy that limits the PCS charge / discharge power. Finally, when the battery voltage reaches the extreme high-risk zone, the system implements a high-voltage power-down strategy, reducing the PCS charge / discharge power to zero. This progressive power control mechanism ensures gradual, rather than abrupt, power adjustments when the battery faces overvoltage risk, minimizing impact on the battery and helping to extend its lifespan.

[0117] By setting different battery voltage thresholds to trigger different levels of protection strategies, the energy storage system can achieve more refined safety management. Alarm strategies, charge and discharge prohibition strategies, and high-voltage power-off strategies form a gradient protection system ranging from minor warnings to emergency power outages, ensuring appropriate safety responses at different voltage levels.

[0118] Because different strategies correspond to gradually increasing single-cell voltages, this design enables the system to flexibly adjust its response measures based on the specific battery voltage conditions. Whether it is a slight voltage fluctuation or a severe overvoltage condition, it can be responded to in a timely and appropriate manner.

[0119] Early intervention of alarm strategies and charge and discharge prohibition strategies can prevent the battery voltage from reaching the level of high voltage and power failure. This not only reduces hardware damage caused by battery overvoltage, but also reduces maintenance and repair costs, while also reducing system downtime.

[0120] For users, this hierarchical protection strategy can provide clear early warning signals, allowing users to understand changes in battery status and have enough reaction time to take action, avoiding the inconvenience and loss caused by sudden power outages and improving the overall user experience.

[0121] In the embodiment of the present application, the above method further includes:

[0122] Predicting the single cell voltage and the predicted total battery voltage at a future target time point based on the single cell voltage and the battery total voltage obtained in the current time period;

[0123] Based on the predicted single cell voltage, a first pre-protection strategy is initiated, wherein the first pre-protection strategy includes at least one of pre-reducing PCS charge and discharge power, pre-enhancing cooling, and optimizing load charge distribution;

[0124] Based on the predicted single cell voltage, a second pre-protection strategy is initiated. The second pre-protection strategy includes at least one of pre-reducing the charging and discharging power of the PCS, pre-cutting off the charging branch, and pre-fault isolation.

[0125] In the embodiment of the present application, by predicting the predicted single cell voltage and the predicted total battery voltage at a future target time point, and activating the first pre-protection strategy and the second pre-protection strategy based on these prediction results, the technical effects are as follows:

[0126] Predictions based on current battery voltage and total pressure data can identify potential increases in battery voltage and total pressure in advance, enabling the initiation of appropriate preemptive protection strategies. This proactive safety control approach is more effective in preventing overvoltage events than traditional post-event responses, ensuring the safe operation of the energy storage system.

[0127] The first proactive protection strategy, which reduces PCS charge and discharge power, intelligently adjusts the charge and discharge power based on predicted cell voltages to prevent the battery voltage from reaching or exceeding the threshold in the future. This dynamic adjustment mechanism enhances the system's intelligent management capabilities, enabling better adaptation to changes in battery status and maintaining the battery within a safe operating range.

[0128] The preemptive cooling strategy can proactively activate or enhance the cooling system before predicting impending battery overheating or voltage increases, effectively controlling battery temperature and avoiding performance degradation or safety issues caused by high temperatures. This strategy optimizes thermal management, extends battery life, and improves the overall performance of the energy storage system.

[0129] Optimizing load charging distribution can intelligently adjust the charge and discharge loads of different battery modules based on the predicted battery voltage distribution, ensuring overall voltage balance in the system and preventing certain battery modules from reaching overvoltage conditions prematurely, thereby improving the efficiency and reliability of the energy storage system.

[0130] The pre-cut-off of charging branches and pre-fault isolation in the second pre-protection strategy can take isolation measures in advance before predicting that the battery voltage may increase abnormally, and cut off the battery cells that may have faults or overvoltage risks, to avoid affecting the stability and safety of the entire system, thereby enhancing the system's self-protection capabilities.

[0131] By implementing a pre-protection strategy, a series of intervention measures can be taken before the battery voltage and total voltage reach an emergency state, reducing the need for emergency shutdown or high-voltage power-off, lowering the probability of sudden failures, and improving the system's continuous operation capability and user satisfaction.

[0132] The implementation of the pre-protection strategy not only avoids overcharging and over-discharging of the battery, but also enables more efficient utilization of resources within the energy storage system by optimizing load charging distribution and enhancing cooling, thereby improving the overall energy conversion efficiency and the economy of system operation.

[0133] The embodiment of the present application provides an energy storage system, such as Figure 4As shown, including:

[0134] Multiple battery clusters, any of the above battery clusters includes multiple single cells connected in series, the single cells are Figure 4 Battery PACK in;

[0135] Multiple battery management units are electrically connected to the above-mentioned single batteries in a one-to-one correspondence; the battery management units refer to Figure 4 BMU (Battery Management Unit);

[0136] Multiple battery control units, one battery control unit is connected to multiple battery management units via a bus, and the number of the battery control units is equal to the number of the battery clusters;

[0137] Battery Control Unit Figure 4 BCU (Battery Control Unit);

[0138] A network switch and a system control unit, wherein each of the battery control units is connected to the network switch via a bus, and the network switch is connected to the system control unit via a bus;

[0139] System control unit see Figure 4 SCU (System Control Unit);

[0140] an energy storage converter connected to the system control unit via a bus, and having a charging branch connected to the single battery;

[0141] Energy storage converter Figure 4 PCS (Power Conversion System);

[0142] Among them, the above-mentioned battery management unit BMU is used to obtain the voltage of the single cell battery, and the above-mentioned battery control unit is used to start a first multi-level protection strategy when the voltage of the single cell battery meets a first preset condition. The above-mentioned first multi-level protection strategy includes adopting different charge and discharge protection strategies when the voltage of the single cell battery reaches different preset single cell voltages. The above-mentioned energy storage converter PCS is used to monitor the total voltage of the battery and is used to start a second multi-level protection strategy when the total voltage of the battery battery meets a second preset condition. The above-mentioned second multi-level protection strategy includes adopting different charge and discharge protection strategies when the total voltage of the battery battery reaches different preset total pressures.

[0143] based on Figure 4In the energy storage system, each battery management unit (BMU) in the system is directly connected to the single battery and can obtain the battery voltage in real time. This enables accurate monitoring of the status of each battery in the energy storage system. Compared with the centralized monitoring system, distributed monitoring can more quickly identify and respond to local overvoltage events, improving the system's response speed and overall monitoring accuracy.

[0144] The battery control unit (BCU) and multiple battery management units (BMUs) form the second-level control layer, which aggregates data from the BMUs and activates the first multi-level protection strategy based on the first preset conditions. The power storage converter (PCS), located at a higher control level, is responsible for monitoring the entire system status and total battery voltage, enabling global regulation of the multi-level overvoltage protection strategy. This hierarchical control structure enables the system to monitor battery status from a micro perspective, coordinate the operation of battery clusters from a meso perspective, and control the safety and efficiency of the entire energy storage system from a macro perspective, forming an intelligent, adaptive control system.

[0145] By setting different levels of preset single-cell voltage and total voltage, the system can respond to even the slightest change in battery status, rather than waiting until a serious problem occurs. This not only effectively prevents overcharging and over-discharging, but also optimizes the battery charging and discharging process by dynamically adjusting the charge and discharge power, reducing energy loss and improving the overall energy efficiency of the system.

[0146] The system's modular design, with multiple battery clusters, battery management units, and control units, makes it easy to expand and maintain. Adding new battery clusters simply requires increasing the number of battery management units and control units, without changing the overall architecture. This significantly enhances the system's design flexibility and future expansion potential.

[0147] In addition to the protection mechanisms of the PCS and BCU, the system also includes an SCU as a higher-level controller, which comprehensively monitors the operating status of the entire network and, when necessary, takes further safety measures, such as initiating a second multi-level protection strategy. This multi-layered defense mechanism provides additional safety redundancy. Even if a control layer fails, the higher-level controller can still take over and ensure safe system operation.

[0148] Through early warning and hierarchical response, the system can promptly detect and address overvoltage issues, reducing the probability of battery failure. Furthermore, the clearly defined control structure and redundant design improve the operational reliability of the entire energy storage system, reducing the risk of system collapse due to single component failure.

[0149] It is additionally noted that Figure 4 The battery management unit BMU is used to execute all the solutions related to the first multi-level protection strategy in the method embodiment, and will not be described again;

[0150] It is additionally noted that Figure 4 The energy storage converter PCS is used to execute all the solutions related to the second multi-stage protection strategy in the method embodiment, and will not be described again;

[0151] In addition, the energy storage system also includes: an energy management system connected to the system control unit via a bus. Figure 4 The EMS (Energy Management System) in the energy storage system is connected to the SCU via a bus. The SCU is responsible for controlling the various components within the energy storage system, while the EMS performs global management and optimization of the energy storage system at a higher level. The synergy between the two enables the energy storage system to not only operate safely and reliably, but also respond efficiently and intelligently to the needs of the external power network and achieve its optimal performance.

[0152] Also, see Figure 4 The energy storage system further includes: a plurality of high-voltage boxes, each of which contains a battery control unit and a charging branch circuit. The charging branch circuit includes a branch circuit breaker, a contactor, and a total voltage fuse.

[0153] exist Figure 4 In the energy storage system shown, the design of multiple high-voltage boxes and the charging branches and battery control unit (BCU) contained within them jointly improve the following technical effects of the system:

[0154] The high-voltage box is an independent modular unit, and each box contains a BCU and corresponding charging branch. This design facilitates the installation, maintenance and expansion of the system. The number of high-voltage boxes can be flexibly increased or decreased according to demand to adapt to energy storage projects of different scales.

[0155] Each charging branch in the high-voltage box is equipped with a branch circuit breaker and a main voltage fuse, which can quickly cut off the circuit in the event of overload, short circuit or voltage abnormality, preventing safety accidents such as electrical fires and providing multiple safety protections.

[0156] Through the close integration of the BCU and the charging branch, refined charge and discharge management of each battery cell or battery cluster can be achieved, including real-time monitoring of battery status, adjustment of charging strategies, and avoidance of overcharge and over-discharge, thereby effectively extending battery life and improving energy storage efficiency.

[0157] When a battery or charging branch in a high-voltage box fails, the fault can be isolated by disconnecting the branch circuit breaker of the box without affecting the operation of other high-voltage boxes, thereby improving the overall fault tolerance and recovery speed of the system.

[0158] The charging branch controls the access of the battery through a contactor, which can reduce unnecessary energy consumption. At the same time, through intelligent control of the charging process, it improves the efficiency of energy conversion and storage and reduces energy waste.

[0159] The modular design makes it easy to locate and replace faulty components, reducing maintenance workload and downtime, and improving system availability and maintenance efficiency.

[0160] In summary, through the modular design of the high-voltage box and the precise configuration of the charging branches, the energy storage system achieves higher safety, scalability, management efficiency, and energy utilization efficiency. It also improves the system's fault response capability and maintenance convenience, which is an important progress in the field of energy storage technology.

[0161] The embodiment of the present application provides an energy storage system, such as Figure 5 As shown, including:

[0162] Multiple battery clusters, any of which includes multiple single cells connected in series. Figure 5 Medium battery PACK;

[0163] Multiple battery management units are electrically connected to the above-mentioned single batteries in a one-to-one correspondence; the battery management units refer to Figure 5 BMU (Battery Management Unit);

[0164] Multiple energy storage converters, any of which includes a battery control unit, a charging branch, and an auxiliary control unit. One battery control unit is connected to multiple battery management units via a bus. The number of battery control units is equal to the number of battery clusters. Figure 5 PCS in;

[0165] Auxiliary control unit see Figure 5 ARM+DSP in;

[0166] Battery Control Unit Figure 5 BCU (Battery Control Unit);

[0167] A network switch and a system control unit, each of the energy storage converters is connected to the network switch via a bus, and the network switch is connected to the system control unit via a bus;

[0168] System control unit see Figure 5 SCU (System Control Unit);

[0169] Among them, the above-mentioned battery management unit BMU is used to obtain the voltage of the single cell battery, and the above-mentioned battery control unit BCU is used to start a first multi-level protection strategy when the voltage of the single cell battery meets a first preset condition. The above-mentioned first multi-level protection strategy includes adopting different charge and discharge protection strategies when the voltage of the single cell battery reaches different preset single cell voltages. The above-mentioned auxiliary control unit is used to monitor the total voltage of the battery and to start a second multi-level protection strategy when the total voltage of the battery battery meets a second preset condition. The above-mentioned second multi-level protection strategy includes adopting different charge and discharge protection strategies when the total voltage of the battery battery reaches different preset total pressures.

[0170] The energy storage system provided in the embodiments of the present application achieves refined management of battery status through its unique network architecture and hierarchical protection strategy. Its technical effects can be summarized as follows:

[0171] Each single cell has a corresponding battery management unit (BMU) for voltage monitoring. This one-to-one monitoring method improves data accuracy and response speed, ensuring that the system can promptly detect and handle single cell overvoltage conditions.

[0172] The system design comprises a multi-layered control architecture, encompassing both local and global control. The BCU is responsible for first-level protection, directly controlling charge and discharge power. The ARM+DSP, as part of the PCS, monitors total battery voltage and implements second-level protection strategies. The SCU, acting as the upper-level controller, provides global coordination and emergency response. This architecture not only improves system response speed but also enhances redundancy and stability.

[0173] The introduction of the first and second multi-level protection strategies enables the system to take different levels of protection measures based on the severity of overvoltage. This intelligent hierarchical protection not only improves safety but also avoids unnecessary over-protection, maintaining efficient system operation.

[0174] Through close collaboration between the BMU and BCU, the system can adjust its charge and discharge strategies at the earliest stages of overvoltage, avoiding energy waste and shortened battery life caused by overvoltage. The auxiliary control unit (ARM+DSP) in the PCS monitors the total battery voltage and adjusts the PCS operating mode accordingly, ensuring more efficient energy distribution across the entire energy storage system and improving energy efficiency.

[0175] Each battery cluster is equipped with an independent energy storage converter PCS, a battery control unit BCU, and an auxiliary control unit ARM+DSP. This modular design makes the system easy to expand horizontally. At the same time, due to the independence of each PCS, BCU, and ARM+DSP, the failure of a single component will not affect the entire system, reducing maintenance difficulty and downtime.

[0176] All BCUs and SCUs are connected via a network switch, forming an efficient and stable communication network. This network design improves data transmission efficiency. At the same time, because data is transmitted on the bus, it enhances communication security and reduces system risks caused by communication failures.

[0177] The flexibility of the system architecture enables it to adapt to energy storage needs of different scales. Whether it is a small household energy storage system or a large industrial energy storage facility, it can achieve efficient and safe energy storage and conversion by adjusting the number of battery clusters and the corresponding PCS and BCU configurations.

[0178] In summary, the energy storage system of this application significantly improves the safety, operating efficiency and flexibility of the energy storage system through its hierarchical protection and control structure, intelligent graded overvoltage protection mechanism, modular design, optimized energy management and powerful communication capabilities, providing new ideas and solutions for the development of energy storage technology.

[0179] It is additionally noted that Figure 5 The battery management unit BMU is used to execute all the solutions related to the first multi-level protection strategy in the method embodiment, and will not be described again;

[0180] It is additionally noted that Figure 5 The battery control unit BCU is used to execute all the solutions related to the second multi-level protection strategy in the method embodiment, and will not be described again;

[0181] The above energy storage system also includes: an energy management system, which is connected to the system control unit via a bus. Figure 5 The EMS in the energy storage system. The EMS, in conjunction with the SCU, monitors the health of the energy storage system in real time, preventing potential failures and ensuring safe and reliable system operation, thereby reducing energy losses and safety incidents caused by system instability. The EMS collects and analyzes large amounts of operational data, providing data support for system maintenance, upgrades, and fault prediction, helping operators make data-driven decisions and further improving system performance and O&M efficiency.

[0182] The energy storage system further comprises: a plurality of battery cabinets, the number of the battery cabinets being equal to the number of the battery clusters;

[0183] Among them, one of the above-mentioned battery clusters, one of the above-mentioned energy storage converters, the above-mentioned network switch and the above-mentioned system control unit are integrated in a target battery cabinet, the above-mentioned target battery cabinet is one of the multiple above-mentioned battery cabinets, and one of the above-mentioned battery clusters and the above-mentioned energy storage converter is integrated in a non-target battery cabinet.

[0184] Integrating a battery cluster, a PCS, a network switch, and an SCU into a single target battery cabinet makes the energy storage system highly modular and standardized. This design facilitates system design, production, transportation, and on-site deployment, significantly reducing installation and commissioning costs while also facilitating subsequent system maintenance and upgrades.

[0185] The non-target battery cabinet integrates only one battery cluster and one PCS, while the key control and communication functions are performed by the SCU and network switch in the target battery cabinet. This architecture simplifies the internal complexity of the system, reduces the delay of control signals, and improves the system's response speed and overall efficiency.

[0186] Because the number of battery cabinets and battery clusters matches, more non-target battery cabinets can be quickly added according to project needs, achieving flexible expansion of system capacity. Furthermore, because the target battery cabinets integrate key control and communication equipment, system expansion does not require redesigning the core architecture, simplifying the expansion process.

[0187] The integrated battery cabinet design ensures more stable connections between key components, reducing failures caused by poor wiring or signal interference. The internal independence of each battery cabinet also means that even if a problem occurs in one cabinet, it will not immediately affect the operation of the entire system, enhancing the system's fault tolerance and fault isolation capabilities.

[0188] By sharing the SCU and network switches in the target battery cabinet, non-target battery cabinets no longer need to be equipped with these devices, saving costs and optimizing space layout. Centralized control and communication equipment also facilitates unified management, reducing maintenance manpower and material investment.

[0189] The energy storage converter further includes: a DCAC converter electrically connected to the charging branch. Figure 5 The DC / AC charging branch includes a fuse, a contactor module KM, and a circuit breaker QS. Specifically, one charging branch includes a circuit breaker QS, a contactor module KM, and a fuse connected in series. One end of the circuit breaker is electrically connected to the battery cell, and one end of the fuse is electrically connected to one end of the DC / AC converter.

[0190] As an important component of the energy storage converter (PCS), the DC / AC converter (i.e., DC to AC converter) is electrically connected to the fuse, contactor module KM, and circuit breaker QS in the charging branch. Its technical effects are mainly reflected in the following aspects:

[0191] A DC / AC converter converts DC power to AC power and vice versa. In an energy storage system, it converts DC power stored in batteries for use in the AC power grid, or converts AC power from the grid into DC power suitable for battery charging, thus achieving a two-way flow and conversion of energy.

[0192] The integration of fuses, contactor modules KM, and circuit breakers QS provides multiple protection mechanisms in the charging branch. These mechanisms can quickly cut off the circuit in the event of overcurrent, short circuit, or abnormal voltage, protecting the DC / AC converter and battery from damage and significantly improving the overall safety and reliability of the energy storage system.

[0193] The contactor module KM plays a key control role in the charging and discharging process. It can accurately control the charging and discharging status according to the instructions of the system control unit (SCU), ensuring the efficient operation of the PCS, while avoiding excessive charging and discharging of the battery and extending the battery life.

[0194] Through advanced power electronics technology, DC / AC converters can achieve high-efficiency energy conversion during charging and discharging, reducing energy loss during the conversion process and improving the energy utilization efficiency of the energy storage system.

[0195] The DC / AC converter can adjust the output AC frequency and phase according to the real-time needs of the power grid, ensuring the synchronous operation of the energy storage system and the power grid, and improving the response speed and adaptability of the energy storage system to the needs of the power grid.

[0196] The introduction of QS circuit breakers enables rapid system recovery in the event of a fault. Once an anomaly, such as overvoltage or overcurrent, is detected, the QS immediately disconnects the circuit to prevent the fault from spreading. Once the fault is resolved, the circuit can be safely reconnected, reducing system downtime and improving system availability and fault recovery capabilities.

[0197] When performing system maintenance or operation, the presence of fuses, contactor modules and circuit breakers provides safety protection, ensures the safety of maintenance personnel and the system during operation, and reduces operational risks.

[0198] In summary, the combination of DC / AC converters and protection components in the charging branch not only improves the energy conversion efficiency and flexibility of energy storage systems, but also enhances system safety and reliability. This is an indispensable key technology in energy storage systems. The application of this technology is of great significance for achieving efficient and stable operation of energy storage systems in smart grids.

[0199] The energy storage system further includes a dehumidifier, a liquid cooler, a temperature and humidity sensor, and a water immersion sensor, each of which communicates with the battery control unit via a bus. The battery control unit assigns addresses to the dehumidifier, the liquid cooler, the temperature and humidity sensor, and the water immersion sensor.

[0200] In the above energy storage system, the dehumidifier, liquid cooler, temperature and humidity sensor, water immersion sensor, and battery control unit (BCU) are integrated through bus communication. The BCU assigns addresses, which brings a series of technical benefits:

[0201] Temperature, humidity, and water immersion sensors can monitor the temperature, humidity, and water immersion status inside the battery cabinet in real time. The BCU automatically controls the operation of the dehumidifier and liquid cooler based on this data, ensuring that the batteries operate in a suitable environment and avoiding battery performance degradation or safety hazards caused by poor environmental conditions.

[0202] Liquid coolers can provide precise temperature control and adjust cooling strategies according to the actual operating conditions of the battery to maintain the battery pack within the optimal operating temperature range, which is crucial for extending battery life and improving energy conversion efficiency.

[0203] The water immersion sensor can promptly detect liquid leakage in the battery cabinet. Once an abnormality is detected, it can immediately notify the BCU to take action, such as activating an alarm, cutting off the power supply, etc., effectively preventing serious accidents such as electrical short circuits or fires.

[0204] As the central control unit, BCU is responsible for communicating with all relevant devices and assigning addresses to them, realizing centralized management and control of environmental control equipment, simplifying the system architecture, improving management efficiency, and reducing the difficulty of operation and maintenance.

[0205] By continuously collecting environmental data and combining it with battery charge and discharge data, the BCU can perform analysis and prediction, identifying potential maintenance needs in advance, such as cooling system performance degradation or dehumidifier filter blockage, so as to carry out targeted maintenance and avoid the impact of sudden failures.

[0206] By intelligently controlling the operation of the dehumidifier and liquid cooler, unnecessary energy consumption is avoided, efficient energy utilization is achieved, and the overall operating cost of the system is reduced.

[0207] The BCU records and analyzes data from temperature, humidity, and water sensors, providing a basis for system performance evaluation and optimization. It also plays an important role in fault analysis, helping to identify the source of faults and improve the accuracy of fault response and handling.

[0208] The bus communication method not only enhances the mutual coordination between the components within the system, but also improves the compatibility of the system, making it easier to add or update environmental control equipment in the future to meet the ever-changing energy storage needs.

[0209] By tightly integrating the dehumidifier, liquid cooler, temperature and humidity sensors, and water immersion sensors into the energy storage system and intelligently managing them through the BCU, this design effectively improves the system's thermal management capabilities, operational safety, and maintenance efficiency. It is an innovative application in the field of environmental control in energy storage technology.

[0210] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present application, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A battery charging and discharging method for an energy storage system, characterized in that: include: Monitor single cell voltage and total battery voltage; When the single cell voltage meets a first preset condition, a first multi-level protection strategy is activated, wherein the first multi-level protection strategy includes adopting different charge and discharge protection strategies when the single cell voltage reaches different preset single cell voltages; When the battery total voltage meets a second preset condition, a second multi-stage protection strategy is started. The second multi-stage protection strategy includes adopting different charge and discharge protection strategies when the battery total voltage reaches different preset total voltages.

2. The battery charging and discharging method of the energy storage system according to claim 1, characterized in that: Before initiating the first multi-stage protection strategy when the single cell voltage satisfies the first preset condition, the method further includes: determining that the single cell voltage satisfies the first preset condition when the single cell voltage reaches any of the preset single cell voltages and maintains the voltage for a corresponding period of time; When the battery total voltage satisfies the second preset condition, before starting the second multi-level protection strategy, the method further includes: when the battery total voltage reaches any of the preset total voltages and maintains the corresponding time, determining that the battery total voltage satisfies the second preset condition.

3. The battery charging and discharging method of the energy storage system according to claim 2, characterized in that: The first multi-level protection strategy includes a first sub-protection strategy, a second sub-protection strategy, and a third sub-protection strategy. When the voltage of the single battery cell meets a first preset condition, the first multi-level protection strategy is activated, including: When the single cell voltage reaches a first preset single cell voltage and maintains for a first time period, a first sub-protection strategy is activated, wherein the first sub-protection strategy is to control the PCS charge and discharge power to drop to a first charge and discharge power; When the single cell voltage reaches a second preset single cell voltage and maintains for a second time period, a second sub-protection strategy is activated, wherein the second sub-protection strategy controls the PCS charge and discharge power to drop to a second charge and discharge power; When the single cell voltage reaches a third preset single cell voltage and maintains for a third time period, a third sub-protection strategy is activated, wherein the third sub-protection strategy controls the PCS charge and discharge power to drop to a third charge and discharge power; Among them, the first preset single cell voltage is less than the second preset single cell voltage, the second preset single cell voltage is less than the third preset single cell voltage, the first time length is greater than the second time length, the second time length is greater than the third time length, the first charge and discharge power is greater than the second charge and discharge power, and the second charge and discharge power is greater than the third charge and discharge power.

4. The battery charging and discharging method of the energy storage system according to claim 2, characterized in that: The second multi-level protection strategy includes a fourth sub-protection strategy, a fifth sub-protection strategy, and a sixth sub-protection strategy. When the battery total voltage meets a second preset condition, the second multi-level protection strategy is activated, including: When the battery total voltage reaches the first preset total voltage and maintains for a fourth time period, a fourth sub-protection strategy is activated, wherein the fourth sub-protection strategy controls the PCS charge and discharge power to decrease to a fourth charge and discharge power; When the single cell voltage reaches the second preset total voltage and maintains for a fifth time period, a fifth sub-protection strategy is activated, wherein the fifth sub-protection strategy controls the PCS charge and discharge power to drop to a fifth charge and discharge power; When the single cell voltage reaches a third preset total voltage and maintains for a sixth time period, a sixth sub-protection strategy is activated, wherein the sixth sub-protection strategy is to control the PCS charge and discharge power to drop to a sixth charge and discharge power; Among them, the first preset total pressure is less than the second preset total pressure, the second preset total pressure is less than the third preset total pressure, the fourth time length is greater than the fifth time length, the fifth time length is greater than the sixth time length, the fourth charge and discharge power is greater than the fifth charge and discharge power, and the fifth charge and discharge power is greater than the sixth charge and discharge power.

5. The battery charging and discharging method of the energy storage system according to claim 1, characterized in that: When the voltage of the single battery cell meets a first preset condition, starting a first multi-level protection strategy includes: When the voltage of the single battery cell meets the first preset condition, one of the alarm strategy, the charge and discharge prohibition strategy and the high voltage power-off strategy is activated; Among them, the alarm strategy is to adjust the PCS to enter the constant voltage charging mode, the charge and discharge prohibition strategy is to limit the PCS charge and discharge power, and the high-voltage power-off strategy is to reduce the PCS charge and discharge power to zero.

6. The battery charging and discharging method of the energy storage system according to any one of claims 1 to 5, characterized in that: The method further comprises: Predicting the single cell voltage and the predicted total battery voltage at a future target time point based on the single cell voltage and the battery total voltage obtained in the current time period; Initiating a first pre-protection strategy based on the predicted single cell voltage, the first pre-protection strategy comprising at least one of pre-reducing PCS charge and discharge power, pre-enhancing cooling, and optimizing load charge distribution; Based on the predicted single cell voltage, a second pre-protection strategy is started, wherein the second pre-protection strategy includes at least one of pre-reducing the PCS charging and discharging power, pre-cutting off the charging branch, and pre-fault isolation.

7. An energy storage system, characterized in that: include: A plurality of battery clusters, any of which comprises a plurality of single cells connected in series; A plurality of battery management units are electrically connected to the single cells in a one-to-one correspondence; Multiple battery control units, one battery control unit is connected to multiple battery management units via a bus, and the number of the battery control units is equal to the number of the battery clusters; A network switch and a system control unit, wherein each battery control unit is connected to the network switch via a bus, and the network switch is connected to the system control unit via a bus; an energy storage converter connected to the system control unit via a bus, and having a charging branch connected to the single battery; In which, the battery management unit is used to obtain the voltage of the single cell battery, and the battery control unit is used to start a first multi-level protection strategy when the single cell battery voltage meets a first preset condition. The first multi-level protection strategy includes adopting different charge and discharge protection strategies when the single cell battery voltage reaches different preset single cell voltages. The energy storage inverter is used to monitor the total battery voltage and to start a second multi-level protection strategy when the total battery voltage meets a second preset condition. The second multi-level protection strategy includes adopting different charge and discharge protection strategies when the total battery voltage reaches different preset total pressures.

8. The energy storage system according to claim 7, characterized in that: The energy storage system further includes: The energy management system is connected to the system control unit via a bus.

9. The energy storage system according to claim 7, characterized in that: The energy storage system further includes: There are multiple high-voltage boxes, and one of the high-voltage boxes contains a battery control unit and a charging branch.

10. An energy storage system, characterized in that: include: A plurality of battery clusters, any of which comprises a plurality of single cells connected in series; A plurality of battery management units are electrically connected to the single cells in a one-to-one correspondence; Multiple energy storage converters, each of which includes a battery control unit, a charging branch, and an auxiliary control unit, one battery control unit being connected to multiple battery management units via a bus, and the number of battery control units being equal to the number of battery clusters; A network switch and a system control unit, wherein each of the energy storage converters is connected to the network switch via a bus, and the network switch is connected to the system control unit via a bus; In which, the battery management unit is used to obtain the voltage of the single cell battery, and the battery control unit is used to start a first multi-level protection strategy when the single cell battery voltage meets a first preset condition. The first multi-level protection strategy includes adopting different charge and discharge protection strategies when the single cell battery voltage reaches different preset single cell voltages. The auxiliary control unit is used to monitor the total battery voltage and to start a second multi-level protection strategy when the total battery voltage meets a second preset condition. The second multi-level protection strategy includes adopting different charge and discharge protection strategies when the total battery voltage reaches different preset total pressures.

11. The energy storage system according to claim 10, characterized in that: The energy storage system further includes: The energy management system is connected to the system control unit via a bus.

12. The energy storage system according to claim 10, characterized in that: The energy storage system further includes: a plurality of battery cabinets, the number of the battery cabinets being equal to the number of the battery clusters; Among them, one battery cluster, one energy storage converter, the network switch and the system control unit are integrated in a target battery cabinet, the target battery cabinet is one of the multiple battery cabinets, and one battery cluster and one energy storage converter are integrated in a non-target battery cabinet.

13. The energy storage system according to claim 10, characterized in that: The energy storage converter further includes: A DCAC converter is electrically connected to the charging branch.

14. The energy storage system according to claim 13, characterized in that: One of the charging branches includes: A circuit breaker, a contactor module and a fuse are connected in series, one end of the circuit breaker is electrically connected to the single battery, and one end of the fuse is electrically connected to one end of the DCAC converter.

15. The energy storage system according to claim 10, characterized in that: The energy storage system further includes: The dehumidifier, the liquid cooler, the temperature and humidity sensor, and the water immersion sensor communicate with the battery control unit via a bus.

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