Control protection method, control device and program product

Abstract

The invention discloses a control protection method, a control device and a program product, the control protection method is applied to an energy storage system, and the energy storage system comprises a plurality of energy storage sub-modules connected in series; the energy storage sub-module comprises an energy storage converter, a protection device and a battery cell, and the protection device is arranged between the energy storage converter and the battery cell; the method comprises the following steps: determining that the energy storage system is switched from a charge-discharge state to a hot standby state; wherein under the condition that the energy storage system is in a hot standby state, the energy storage converter can generate resonance current during working; the protection device is controlled to be connected between the energy storage converter and the single battery, and the protection device is used for absorbing resonance current generated by the energy storage converter during working; and controlling the energy storage system to be switched to the hot standby state. Therefore, when the energy storage system is in the hot standby state, the protection device can be connected to absorb the resonance current generated by the energy storage converter, so that the battery is protected from being damaged by microcirculation, and the service life of the battery is prolonged.

Description

Control and protection methods, control devices and program products Technical Field

[0001] This application relates to the field of battery technology, and in particular to a control and protection method, control device, and program product. Background Technology

[0002] As a flexible power regulation resource, energy storage systems typically operate in three modes: hot standby, maintenance, and operation. When operating in hot standby mode, the power converter (PCS) within the energy storage system remains in a high-frequency switching state, generating common-mode voltage and creating high-frequency reactive power fluctuations on associated reactive components. This results in high-frequency ripple current at the terminals of individual battery cells, impairing battery cycle life. Summary of the Invention

[0003] This application mainly provides a control and protection method, control device, and program product, which can absorb the resonant current generated by the operation of the energy storage converter when the energy storage system is in hot standby state, protect the battery from micro-circulation damage, and extend the battery life.

[0004] The technical solution of this application is implemented as follows.

[0005] In a first aspect, embodiments of this application provide a control and protection method applied to an energy storage system. The energy storage system includes multiple energy storage sub-modules connected in series. Each energy storage sub-module includes an energy storage converter, a protection device, and a battery cell. The protection device is disposed between the energy storage converter and the battery cell. The method includes: determining that the energy storage system is switching from a charging / discharging state to a hot standby state; wherein, when the energy storage system is in the hot standby state, the energy storage converter generates a resonant current during operation; controlling the protection device to be connected between the energy storage converter and the battery cell, the protection device being used to absorb the resonant current generated by the operation of the energy storage converter; and controlling the energy storage system to switch to the hot standby state.

[0006] Through the aforementioned technical means, the energy storage system comprises multiple energy storage sub-modules connected in series. Each sub-module includes protection devices, an energy storage converter, and individual battery cells. When the energy storage system switches from a charging / discharging state to a hot standby state, the protection device is connected between the energy storage converter and the individual battery cells, and then the system switches to hot standby mode. In hot standby mode, the protection device absorbs the resonant current generated by the high-frequency switching of the energy storage converter, blocking the high-frequency components transmitted from the converter to the individual battery cells. This prevents the individual battery cells from being in a micro-circulation charging / discharging state due to the resonant current, thus protecting them from micro-circulation damage and extending their lifespan.

[0007] In some embodiments, the method further includes: determining that the energy storage system switches from a hot standby state to a charge / discharge state; controlling the protection device to disconnect from the corresponding energy storage converter and the corresponding battery cell, wherein the energy storage converter is connected to the battery cell, the energy storage converter being used to output electrical energy to the battery cell or receive electrical energy output by the battery cell; and controlling the energy storage system to switch to the charge / discharge state.

[0008] By employing the aforementioned technical means, when the energy storage system is determined to switch from a hot standby state to a charge / discharge state, the protection device is bypassed, disconnecting the protection device from the energy storage converter and the battery cell. The energy storage converter is then controlled to connect to the corresponding battery cell, allowing it to output or receive electrical energy from the battery cell. This approach takes into account the needs of different energy storage systems under different operating modes, avoids the losses and heat generated by current flowing through the protection device during normal charging and discharging of the energy storage submodule, thereby extending the lifespan of the protection device and improving the energy consumption and reliability of the energy storage system during charging and discharging.

[0009] In some embodiments, the energy storage system further includes a switching module, one end of which is connected to the energy storage inverter, and the other end of which is connected to a protection device and a battery cell. Controlling the connection of the protection device between the energy storage inverter and the battery cell includes: when it is determined that the energy storage system is switching from a charging / discharging state to a hot standby state, controlling the switching module to switch to a first operating state to connect the protection device between the energy storage inverter and the battery cell; or, controlling the protection device to disconnect from the corresponding energy storage inverter and the corresponding battery cell includes: when it is determined that the energy storage system is switching from a hot standby state to a charging / discharging state, controlling the switching module to switch to a second operating state to disconnect the protection device from the corresponding energy storage inverter and the corresponding battery cell.

[0010] Through the aforementioned technical means, the energy storage system switches to a first operating state via a control switch module, connecting the protection device between the energy storage converter and the battery cells. The energy storage system then switches to a second operating state via the same control switch module, bypassing the protection device and directly connecting the energy storage converter to the battery cells. This allows for control over the bypassing and connection of the protection device through the operating modes of the control switch module, improving the control efficiency of connecting and disconnecting the protection device and meeting the protection device requirements of the energy storage system under different operating modes.

[0011] In some embodiments, the switching module includes a first switch and a second switch; the first switch is connected in series with a protection device, and the branch containing the first switch and the second switch are respectively connected between the energy storage converter and the battery cell; the method further includes: controlling the switching module to switch to a first operating state or a second operating state by controlling the first switch and the second switch to be turned on or off.

[0012] Using the aforementioned technical means, the switching module includes a first switch and a second switch. The first switch is connected in series with the protection device, and the second switch is connected in parallel with the branch containing the first switch and the protection device between the energy storage converter and the battery cell. This establishes two current paths between the energy storage converter and the battery cell. Turning on the first switch and turning off the second switch connects the protection device between the energy storage converter and the battery cell; turning on the second switch and turning off the first switch bypasses the protection device, thus meeting the protection device requirements of the energy storage system under different operating modes.

[0013] In some embodiments, controlling the switch module to switch to a first operating state includes: sending a first control signal to the energy storage converter; the first control signal is used to instruct the energy storage converter to control the corresponding battery management system in the energy storage submodule to send a second control signal to the first switch and the second switch; wherein, the second control signal is used to control the corresponding first switch to switch to the on state; and is also used to control the corresponding second switch to switch to the off state when the corresponding first switch is switched to the on state.

[0014] Through the above-mentioned technical means, the energy storage converter in the energy storage submodule receives the first control signal. Based on the first control signal, the energy storage converter instructs the corresponding battery management system to send a second control signal to the first switch and the second switch. The first switch is turned on first, and after the protection device is connected, the second switch is turned off. This not only ensures that the electrical connection between the energy storage converter and the battery cell is not interrupted, but also makes the arc smaller when the first switch is turned on and the second switch is turned off. This avoids connecting the protection device in the hot standby state, reduces the impact of ripple current generated by the operation of the energy storage converter, and extends the service life of the battery cell, the first switch, and the second switch.

[0015] In some embodiments, controlling the switch module to switch to the second operating state includes: sending a third control signal to the energy storage converter; the third control signal is used to instruct the energy storage converter to control the corresponding battery management system in the energy storage submodule to send a fourth control signal to the first switch and the second switch; wherein, the fourth control signal is used to control the corresponding second switch to switch to the on state; and is also used to control the corresponding first switch to switch to the off state when the corresponding second switch is switched to the on state.

[0016] Through the aforementioned technical means, the energy storage converter in the energy storage submodule receives a third control signal. Based on the third control signal, the energy storage converter instructs the corresponding battery management system to send a fourth control signal to the first and second switches. This control signal first turns on the second switch and then turns on the first switch, disconnecting the protection device. This ensures that the electrical connection between the energy storage converter and the battery cell remains uninterrupted when the energy storage system switches operating modes, and smoothly disconnects the protection device. This avoids the losses generated by the protection device during normal charging and discharging of the energy storage submodule, reduces the generation of arcs during the switching on and off processes, extends the life of the switches, and ensures the working stability and reliability of the energy storage system under charging and discharging conditions.

[0017] In some embodiments, the switching module further includes a third switch; the method further includes: when the energy storage system is powered on, sending a fifth control signal to the energy storage converter of each energy storage submodule; the fifth control signal is used to instruct the corresponding third switch to switch to the on state.

[0018] Through the above-mentioned technical means, the switching module also includes a third switch, which provides electrical isolation between the energy storage converter and the battery cells. It can also serve as a redundancy for the second switch, replacing it to perform related functions when the second switch fails, thereby improving the reliability of the energy storage system.

[0019] In some embodiments, the energy storage converter includes multiple switching transistors, the control terminals of which are respectively connected to a control device; before the switching module switches to the first operating state, the method further includes: when it is determined that the energy storage system is switching from a charging / discharging state to a hot standby state, sending a sixth control signal to the energy storage converter in each energy storage submodule; the sixth control signal is used to instruct the corresponding multiple switching transistors to switch to the off state; after the switching module switches to the second operating state, the method further includes: when it is determined that the energy storage system is switching from a hot standby state to a charging / discharging state, sending a seventh control signal to the energy storage converter in each energy storage submodule; the seventh control signal is used to instruct the corresponding multiple switching transistors to switch to the on state.

[0020] By employing the aforementioned technical means, when the energy storage system switches to a hot standby state, the switching transistors of the energy storage converters in each energy storage submodule are locked out, and the high-frequency switching action of each switching transistor is disconnected, but the energy storage converter does not go into hibernation. Then, the operating state of the switching module is switched. When the energy storage system switches to a charge / discharge state, the operating state of the switching module is switched first, and then the switching transistors in each submodule are turned on. This can suppress the generation of common-mode signals from the source, thereby reducing the impact on the lifespan of individual battery cells and extending battery life. It can also enable the energy storage system to respond in a shorter time when switching to a charge / discharge state, reducing response delay.

[0021] Secondly, embodiments of this application provide a control device, which is disposed in an energy storage system. The energy storage system includes multiple energy storage sub-modules connected in series. Each energy storage sub-module includes an energy storage converter, a protection device, and a battery cell. The protection device is disposed between the energy storage converter and the battery cell. The control device is used to determine when the energy storage system switches from a charging / discharging state to a hot standby state. When the energy storage system is in hot standby mode, the energy storage converter generates a resonant current during operation. The protection device is connected between the energy storage converter and the battery cell and is used to absorb the resonant current generated by the energy storage converter. The control device controls the energy storage system to switch to hot standby mode.

[0022] Thirdly, embodiments of this application provide a program product, including a computer program or instructions, which, when executed by a processor, implement the method as described in any of the first aspects.

[0023] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this application. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the composition structure of an energy storage system provided in an embodiment of this application; Figure 2 is a flowchart of a control and protection method provided in an embodiment of this application; Figure 3 is a schematic diagram of a reactive power output curve provided in an embodiment of this application; Figure 4 is a schematic diagram of a reactive power output curve provided in an embodiment of this application; Figure 5 is a flowchart of a control and protection method provided in an embodiment of this application; Figure 6 is a schematic diagram of the composition structure of an energy storage submodule provided in an embodiment of this application; Figure 7 is a schematic diagram of the composition structure of an energy storage submodule provided in an embodiment of this application; Figure 8 is a schematic diagram of the composition structure of an energy storage submodule provided in an embodiment of this application; Figure 9 is a schematic diagram of the composition structure of an energy storage submodule provided in an embodiment of this application. Detailed Implementation

[0025] In order to gain a more detailed understanding of the features and technical content of the embodiments of this application, the implementation of the embodiments of this application will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for reference and illustration only and are not intended to limit the embodiments of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0027] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0028] It should also be noted that the terms "first, second, and third" used in the embodiments of this application are only used to distinguish similar objects and do not represent a specific order of objects. It is understood that "first, second, and third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

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

[0030] The following is a description of the relevant technologies used in this application.

[0031] New energy batteries are being used more and more widely in daily life and industry. For example, new energy vehicles equipped with batteries are already widely used. In addition, batteries are being used more and more in the field of energy storage.

[0032] Currently, new energy batteries are being used more and more widely in daily life and industry. They are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in aerospace and other fields. With the continuous expansion of the application areas of power batteries, the market demand is also constantly increasing.

[0033] In this embodiment, the battery can be a single battery cell. A single battery cell refers to a basic unit capable of converting chemical energy into electrical energy, and can be used to manufacture battery modules or battery packs to supply power to electrical devices. A single battery cell can also be a rechargeable battery, which is a battery cell that can be recharged after discharge to reactivate its active materials and continue to be used.

[0034] In this embodiment, the battery may also be a single physical module comprising one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed via a busbar.

[0035] Energy storage systems are typically in operation for designated periods according to dispatch requirements, either storing or releasing energy, while remaining in hot standby mode for the rest of the time and undergoing maintenance for a small period. Specifically, the time an energy storage system is in operation accounts for approximately 15% to 35% of the total time, the time under maintenance accounts for approximately 1% of the total time, and the time in hot standby mode accounts for approximately 65% ​​to 85% of the total time.

[0036] Currently, when an energy storage system is in hot standby mode, it is typically configured to have zero active and reactive power outputs. In this state, the power supply system (PCS) remains connected to the grid and operates normally. The insulated-gate bipolar transistors (IGBTs) inside the PCS undergo high-frequency switching, generating a high-frequency common-mode voltage. Although a large number of reactance devices are connected in series in the energy storage system, the common-mode voltage does not directly generate active power, but it forms a high-frequency common-mode current path through parasitic capacitance. When the common-mode voltage acts on the reactance devices, it creates reactive power fluctuations on the associated reactance devices. This results in high-frequency ripple current at the terminals of the individual battery cells in the energy storage system, reducing the battery's cycle life.

[0037] Based on this, embodiments of this application provide a control and protection method, control device, and program product. The energy storage system includes multiple energy storage sub-modules connected in series. Each energy storage sub-module includes a protection device, an energy storage converter, and a battery cell. When it is determined that the energy storage system is switching from a charging / discharging state to a hot standby state, the energy storage system control protection device is connected between the energy storage converter and the battery cell, and then the energy storage system is controlled to switch to the hot standby state. In the hot standby state of the energy storage system, the protection device can absorb the resonant current generated by the high-frequency switching of the energy storage converter, blocking the high-frequency components transmitted from the energy storage converter to the battery cell. This prevents the battery cell from being in a micro-circulation charging / discharging state due to the resonant current, thereby protecting the battery from micro-circulation damage and extending the battery's lifespan.

[0038] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0039] In one embodiment of this application, a control and protection method is provided, which is applied to an energy storage system. As shown in FIG1, the energy storage system includes multiple energy storage sub-modules connected in series. The energy storage sub-module includes an energy storage converter, a protection device, and a battery cell. The protection device is disposed between the energy storage converter and the battery cell.

[0040] As shown in Figure 1, in this application and the following embodiments, the flow of the control and protection method for an energy storage system is described using a three-phase AC cascaded scenario as an example. It should be noted that the control and protection method can also be applied to other scenarios, such as DC-connected energy storage systems.

[0041] In this embodiment of the application, as shown in Figure 1, the energy storage system is, for example, a three-phase energy storage system. The grid connection point refers to the point of common coupling (PCC), which is the boundary between the energy storage system and the upstream power grid. The electrical energy input from each energy storage submodule in the energy storage system to the upstream power grid, as well as the electrical energy input from the upstream power grid to each energy storage submodule in the energy storage system, all pass through the grid connection point.

[0042] In this embodiment, the grid connection switch QF1 refers to the main switch between the energy storage system and the upstream power grid. It is connected between the grid connection point and multiple energy storage modules and is usually a circuit breaker or disconnector. The grid connection switch QF1 is used to disconnect the energy storage system from the upstream power grid when the energy storage system needs maintenance or encounters a fault, or to trip when a short circuit or overcurrent occurs inside the energy storage system to protect the energy storage system.

[0043] In this embodiment, the three-phase energy storage system includes three energy storage modules, corresponding to phases A, B, and C respectively. Each corresponding energy storage module includes multiple energy storage sub-modules connected in series. For example, the first energy storage module 1 corresponding to phase A includes energy storage sub-modules SM11, SM12, SM13...SM1n connected in series; the second energy storage module 2 corresponding to phase B includes energy storage sub-modules SM21, SM22, SM23...SM2m connected in series; and the third energy storage module 3 corresponding to phase C includes energy storage sub-modules SM31, SM32, SM33...SM3k connected in series. Here, n, m, and k are all positive integers greater than or equal to 1. One positive terminal of each series-connected energy storage sub-module is connected to the grid-connected switch QF1, and one negative terminal is connected to the grid-connected switch QF1. After connecting multiple energy storage sub-modules in series to the grid voltage, the system is connected to the high-voltage grid via a reactor.

[0044] In this embodiment, the energy storage system may further include a control device 4, which is connected to the energy storage converter in each energy storage submodule and serves as the control center for all energy storage converters. The connection to the energy storage converters in each energy storage submodule is not specifically shown in Figure 1. The control device 4 is the largest management unit in the energy storage system, responsible for controlling the DC-side circuit; for example, it may be a control and protection device.

[0045] Each energy storage submodule is an independent unit. In this embodiment, as shown in Figure 1, the energy storage submodule SM31 is used as an example for explanation. Other energy storage submodules SM in the energy storage system can refer to the structure and control method of the energy storage submodule SM31.

[0046] As shown in Figure 1, the energy storage submodule 31 includes an energy storage converter 311, a protection device 312, and battery cells 313. The protection device 312 is located between the energy storage converter 311 and the battery cells 313, and is connected to the energy storage device via a control interface between the energy storage converter 311 and the battery cells 313, or disconnected from the energy storage converter 311 and the battery cells 313. The battery cells 313 serve as the medium for absorbing or releasing electrical energy from the grid in the energy storage system. The battery cells provide DC voltage, and the energy storage converter 311 converts the DC voltage to AC voltage for supply to the grid, or converts the AC voltage to DC voltage for supply to the battery cells 313.

[0047] As shown in Figure 2, the method may include the following steps S501 to S503.

[0048] S501 determines that the energy storage system switches from a charging / discharging state to a hot standby state; wherein, when the energy storage system is in a hot standby state, the energy storage converter will generate a resonant current when it is working.

[0049] In this embodiment of the application, when the grid-connected switch QF1 is closed, the control device determines that the energy storage system is switching from the charging / discharging state to the hot standby state by receiving an instruction from the upper-level power grid to switch to the hot standby state, an instruction from the user to switch to the hot standby state, or when the preset charging / discharging time period reaches its end time.

[0050] S502, the control and protection device is connected between the energy storage converter and the battery cell. The protection device is used to absorb the resonant current generated by the operation of the energy storage converter.

[0051] When the control device determines that the energy storage system is switching to hot standby mode, it sends a control signal to the energy storage converter in each energy storage submodule, instructing the topology of the control circuit of the energy storage converter in each energy storage submodule to change, and connecting the protection device between the energy storage converter and the battery cell.

[0052] Figure 3 shows the reactive power output of a 35kV, 29-module energy storage system in hot standby mode. The horizontal axis represents time, and the vertical axis represents reactive power (values ​​expressed in terms of time, time, and reactive power). (Calculated in kW). As shown in Figure 3, in the hot standby state, even if the current command is 0, the energy storage converters in each energy storage submodule are still operating normally, generating a high-frequency common-mode voltage in the energy storage system. When the common-mode voltage acts on the reactive devices in the energy storage system, such as filters, the presence of parasitic capacitance will induce a high-frequency resonant current. This will cause the reactor to experience "reactive power jitter," that is, generate a high-frequency reactive power circulating current, causing the energy storage system to continue to experience reactive power jitter involving both release and absorption. Although the average value of this reactive power jitter is very small, it exists continuously during the hot standby period of the energy storage system, meaning that there is a continuous resonant current at the battery port, keeping the battery in a state of "micro-circulation." This high-frequency micro-circulation will exacerbate the side reactions inside the battery, causing the battery's equivalent cycle life to decay faster than during static storage. Over the entire lifespan of the energy storage system, the accumulated ineffective charge and discharge capacity can even reach 400 battery cycles. Since the battery life is usually directly related to the total charge and discharge throughput, this results in unnecessary loss of battery life.

[0053] Based on this, in this embodiment, before the energy storage system switches to hot standby mode and enters hot standby mode, a protection device is connected between the energy storage converter and the battery cells. The protection device is used to absorb the resonant current generated by the operation of the energy storage converter. Thus, after the energy storage system enters hot standby mode, the energy storage converter operates normally in this state, and the generated resonant current is absorbed by the protection device between the energy storage converter and the battery cells. The resonant current is not transmitted to the battery cells, avoiding lifespan degradation caused by micro-charging or micro-discharging of the battery cells due to the resonant current. As shown in Figure 4, after connecting the protection device, under the same conditions as Figure 3, when the energy storage system is in hot standby mode, the battery current decreases by several orders of magnitude, thereby significantly reducing unnecessary cycle life loss of the battery.

[0054] In this embodiment, the protection device may be, for example, a pre-charge resistor, which is a standard configuration on the DC side of the PCS. However, in related technologies, the pre-charge resistor is a short-time operating resistor, typically used only to withstand inrush currents within 1-2 seconds before the energy storage system is connected to the grid. In this embodiment, by reusing the pre-charge resistor, a switching module is added, and the logic program of the control device is modified. By controlling the switching module, when the energy storage system is in hot standby mode, the protection device is connected between the energy storage converter and the battery cell. The current path is: grid... Energy storage converters for each energy storage submodule Protection devices For the corresponding battery cell, this is equivalent to inserting a physical impedance between the energy storage converter and the battery cell, which can directly block the resonant current generated by the common-mode voltage, reduce the impact of the high-frequency resonant current on the battery cell, reduce hardware investment, and reduce circuit complexity.

[0055] S503 controls the energy storage system to switch to hot standby mode.

[0056] In this embodiment, the control device controls the loop current in each energy storage submodule to decrease, thereby controlling the energy storage system to enter a hot standby state. The control device determines whether the energy storage system has switched to a hot standby state by detecting the DC bus voltage, the main loop current, and the current reported by the energy storage converter in each energy storage submodule.

[0057] It should be noted that, in the embodiments of this application, the control device can also independently control the working status of each energy storage submodule in the energy storage system based on parameters such as scheduling time period and scheduling power in historical data. For example, during the scheduling off-peak period at night, all energy storage submodules in the energy storage system are in hot standby state, and protection devices are connected between the energy storage inverter and the battery cell of each energy storage submodule. During periods when scheduling is more frequent and the scheduling power demand is lower than the preset power value, at least some of the energy storage submodules can be controlled to switch to hot standby state. For the energy storage submodules that have switched to hot standby state, the protection devices in these energy storage submodules are connected between the energy storage inverter and the battery cell. During periods when scheduling is more frequent and the scheduling power demand is lower than the preset power value, all energy storage submodules can be controlled to enter the charging and discharging state.

[0058] It should also be noted that in some embodiments, since the hot standby state may last for a long time, although the current value generated by reactive power jitter is very small, the long-term current flow may cause the resistor to continuously heat up. Based on this, the model of the pre-charge resistor can be replaced to ensure that the heat capacity of the pre-charge resistor can withstand the heat generation of the energy storage system in the hot standby state.

[0059] In some embodiments, the temperature of the protection device can be monitored to prevent it from overheating and burning out during prolonged hot standby.

[0060] This application provides a control and protection method. The energy storage system includes multiple energy storage sub-modules connected in series. Each sub-module includes a protection device, an energy storage converter, and a battery cell. When the energy storage system is determined to switch from a charging / discharging state to a hot standby state, the energy storage system controls the protection device to connect between the energy storage converter and the battery cell, and then controls the energy storage system to switch to the hot standby state. In the hot standby state, the protection device can absorb the resonant current generated by the high-frequency switching of the energy storage converter, blocking the high-frequency components transmitted from the energy storage converter to the battery cell. This prevents the battery cell from being in a micro-circulation charging / discharging state due to the resonant current, thereby protecting the battery from micro-circulation damage and extending the battery's lifespan.

[0061] In some embodiments, as shown in FIG5, the method may further include the following steps S601 to S603.

[0062] S601, determine the energy storage system to switch from hot standby state to charging and discharging state.

[0063] In this embodiment of the application, when the grid-connected switch QF1 is closed, the control device determines that the energy storage system is switching from the hot standby state to the charging and discharging state by receiving the instruction from the upper-level power grid to switch to the charging and discharging state, the instruction from the user to switch to the charging and discharging state, or when the preset hot standby time period reaches its end time.

[0064] S602, the control and protection device is disconnected from the corresponding energy storage converter and the corresponding battery cell, and the energy storage converter is connected to the battery cell. The energy storage converter is used to output electrical energy to the battery cell or receive electrical energy output by the battery cell.

[0065] As shown in Figure 1, when the control device determines that the energy storage system is preparing to switch from a hot standby state to a charging / discharging state, before the energy storage system switches to the charging / discharging state, the control device sends a control signal to the energy storage converter in each energy storage submodule, instructing the energy storage converter in each energy storage submodule to bypass the protection device. Taking energy storage submodule SM31 31 as an example, the energy storage converter 311, based on the instruction of the control device, bypasses the protection device 312 and exits the main power circuit. At this time, the current circuit is: grid Energy storage converters for each energy storage submodule The corresponding battery cells ensure the ability of the battery cells to input or receive current during charging and discharging.

[0066] S603 controls the energy storage system to switch to charging and discharging state.

[0067] In this embodiment, the control device controls the increase of the loop current in each energy storage submodule to control the energy storage system to enter the charging and discharging state. The control device determines whether the energy storage system has switched to the charging and discharging state by detecting the DC bus voltage, the main loop current, and the current reported by the energy storage converter in each energy storage submodule.

[0068] In the embodiments of this application, after each energy storage submodule switches to the charging and discharging state, the current output by the energy storage converter directly charges the corresponding battery cell without passing through the protection device; or, the current output by the battery cell directly supplies power to the grid through the energy storage converter without passing through the protection device.

[0069] This application provides a control and protection method. When it is determined that the energy storage system is switching from a hot standby state to a charge / discharge state, the protection device is bypassed, the connection between the protection device and the energy storage converter and the battery cell is disconnected, and the energy storage converter is controlled to connect to the corresponding battery cell. The energy storage converter outputs electrical energy to the battery cell or receives electrical energy output by the battery cell. This method takes into account the needs of different energy storage systems in different operating modes, avoids the loss and heat generated by the current flowing through the protection device during normal charging and discharging of the energy storage submodule, thereby extending the life of the protection device and improving the energy consumption and reliability of the energy storage system in the charging and discharging state.

[0070] In some embodiments, as shown in FIG6, the energy storage system further includes a switch module 314, one end of which is connected to the energy storage converter 311, and the other end of which is connected to the protection device 312 and the battery cell 313.

[0071] It should be noted that after the energy storage system is powered on, the control device determines the operating state of the switching modules in each energy storage submodule based on the operating mode to be switched by the energy storage system. For example, if the control device determines that the energy storage system is currently switching to a hot standby state, it controls the switching modules to switch to the first operating state; or, if the control device determines that the energy storage system is currently switching to a charging / discharging state, it controls the switching modules to switch to the second operating state.

[0072] In some embodiments, controlling the protection device to be connected between the energy storage converter and the battery cell includes: when it is determined that the energy storage system is switching from a charging / discharging state to a hot standby state, controlling the switch module to switch to a first operating state and connecting the protection device between the energy storage converter and the battery cell.

[0073] In the first working state, the switch module 314 means that multiple switches in the switch module are turned on or off to change the connection relationship of the circuit and connect the protection device between the energy storage converter and the battery cell.

[0074] It should be noted that after all the switching modules of each energy storage submodule are switched to the first working state, the energy storage system enters the hot standby state.

[0075] Alternatively, in some embodiments, disconnecting the protection device from the corresponding energy storage converter and the corresponding battery cell includes: when it is determined that the energy storage system is switching from a hot standby state to a charge / discharge state, controlling the switch module to switch to a second operating state to disconnect the protection device from the corresponding energy storage converter and the corresponding battery cell.

[0076] In this embodiment, the second working state of the switch module 314 means that the multiple switches in the switch module 314 are turned on or off to change the connection relationship of the circuit, bypass the protection device, and the energy storage converter 311 is directly connected to the battery cell 313.

[0077] It should also be noted that after the switching modules of each energy storage submodule are switched to the second working state, the energy storage system enters the charging and discharging state.

[0078] This application provides a control and protection method. The energy storage system switches to a first operating state via a control switch module, connecting a protection device between the energy storage converter and the battery cell. The energy storage system then switches to a second operating state via the control switch module, bypassing the protection device and directly connecting the energy storage converter to the battery cell. This allows for control of the bypassing and connection of the protection device through the operating mode of the control switch module, improving the control efficiency of connecting and disconnecting the protection device and meeting the protection device requirements of the energy storage system under different operating modes.

[0079] In some embodiments, as shown in FIG6, the switch module includes a first switch K1 and a second switch K2.

[0080] The first switch K1 is connected in series with the protection device, and the branch where the first switch K1 is located and the second switch K2 are respectively connected between the energy storage converter 311 and the battery cell 313.

[0081] In some embodiments, the method may further include: controlling the switch module to switch to a first working state or a second working state by controlling the first switch and the second switch to turn on or off.

[0082] Figure 6 shows a schematic diagram of the composition structure of any energy storage submodule SM in Figure 1. In the embodiments of this application and the following embodiments, the circuit structure of any energy storage submodule is used as an example for explanation.

[0083] In this embodiment of the application, as shown in FIG6, a second switch K2 is connected in series between the energy storage converter 311 and the battery cell 313, a first switch K1 is connected to a protection device, the branch containing the first switch K1 and the protection device is connected in parallel with the branch containing the second switch K2, and the branch is connected between the energy storage converter 311 and the battery cell 313.

[0084] It should be noted that Figure 6 shows a connection example of the first switch K1, the second switch K2 and the protection resistor R1. The functions in the above embodiments can be achieved by adopting other connection relationships, topologies and switch control methods based on actual needs and circuit layout. For example, the protection device can be connected in series with the second switch K2. No specific limitation is made here.

[0085] In this embodiment, when it is determined that the energy storage system is switching to a hot standby state, the first switch is turned on and the second switch is turned off, and the switch module is switched to a first operating state, connecting the protection device between the energy storage converter and the battery cell; or, when it is determined that the energy storage system is switching to a charge / discharge state, the second switch is turned on and the first switch is turned off, and the switch module is switched to a second operating state, bypassing the protection device, and the energy storage converter and the corresponding battery cell are directly connected.

[0086] This application provides a control and protection method. The switching module includes a first switch and a second switch. The first switch is connected in series with a protection device, and the second switch is connected in parallel with the first switch and the branch containing the protection device between the energy storage converter and the battery cell. This establishes two current paths between the energy storage converter and the battery cell. Turning on the first switch and turning off the second switch connects the protection device between the energy storage converter and the battery cell, while turning on the second switch and turning off the first switch bypasses the protection device, thus meeting the protection device requirements of the energy storage system under different operating modes.

[0087] In some embodiments, referring to FIG6, the aforementioned step of controlling the switch module to switch to the first working state may include: sending a first control signal to the energy storage converter; the first control signal is used to instruct the energy storage converter to control the corresponding battery management system (BMS) in the energy storage submodule to send a second control signal to the first switch and the second switch.

[0088] The second control signal is used to control the corresponding first switch to switch to the on state; and also to control the corresponding second switch to switch to the off state when the corresponding first switch is switched to the on state.

[0089] In this embodiment, each energy storage submodule includes a battery management system (BMS). The BMS of each submodule is connected to the corresponding energy storage converter 311. The BMS is also connected to the first switch K1 and the second switch K2 in the same submodule. In some embodiments, the BMS is also connected to the battery cell 313. The BMS and its connection relationship with each device are not shown in Figure 6.

[0090] In this embodiment of the application, when the control device determines that the energy storage system has switched from a charging / discharging state to a hot standby state, it generates a first control signal and sends the first control signal to the energy storage converter of each energy storage submodule.

[0091] After receiving the first control signal, the energy storage converter of each energy storage submodule communicates with the corresponding battery management system through the communication bus inside the energy storage submodule, instructing the battery management system to generate a second control signal and send the second control signal to the first switch and the second switch of the same energy storage submodule.

[0092] In this embodiment of the application, taking the energy storage submodule SM31 31 as an example, the battery management system in the energy storage submodule sends a second control signal to the first switch K1 and the second switch K2 based on the instruction of the energy storage converter 311, and performs timing control on the first switch K1 and the second switch K2.

[0093] In this embodiment of the application, the timing control logic executed by the battery management system on the first switch K1 and the second switch K2 includes: firstly, based on the second control signal sent to the first switch K1, the first switch K1 is driven to switch from the off state to the on state. At this time, the second switch K2 is still in the on state (when the energy storage system was in a charging and discharging state before).

[0094] When the second switch K2 is still in the conducting state, the first switch K1 is also conducting. The current of the energy storage converter 311 will flow through the branches where the first switch K1 and the second switch K2 are located at the same time. Since the branch where the second switch K2 is located is a low-resistance path, most of the current still flows through the branch where the second switch K2 is located, and a small portion of the current flows through the branch where the first switch K1 is located. Therefore, the arc impact is small when the first switch K1 is turned on, which can prevent the first switch K1 from sticking and reduce the impact on the life of the first switch K1 contacts.

[0095] When the first switch K1 is switched to the ON state, the battery management system drives the second switch K2 based on the second control signal sent to the second switch K2, controlling the second switch K2 to switch from the ON state to the OFF state. After the second switch K2 is turned off, since the branch containing the first switch K1 is already conductive and the protection device is connected in series with the first switch K1, the current is switched from the branch containing the second switch K2 to the branch containing the first switch K1. Because of the presence of the protection device, the current switching process is smooth and no overvoltage will occur.

[0096] It should be noted that, in this embodiment, after the battery management system completes the control of the first switch K1 and the second switch K2, it sends the relevant status of the switching completion to the energy storage converter. The energy storage converter reports the relevant information of the switching completion to the control device. After determining that the first switch and the second switch in each energy storage submodule have been switched, the control device issues relevant control commands for the thermal standby state to each energy storage submodule in the energy storage system, controlling the energy storage system to switch to the thermal standby state.

[0097] This application provides a control and protection method. The energy storage converter in the energy storage submodule receives a first control signal. Based on the first control signal, the energy storage converter instructs the corresponding battery management system to send a second control signal to the first switch and the second switch. The first switch is controlled to turn on first, and after the protection device is connected, the second switch is controlled to turn off. This not only ensures that the electrical connection between the energy storage converter and the battery cell is not interrupted, but also makes the arc smaller when the first switch is turned on and the second switch is turned off. It avoids connecting the protection device in the hot standby state, reduces the impact of ripple current generated by the operation of the energy storage converter, and extends the service life of the battery cell, the first switch and the second switch.

[0098] In some embodiments, referring to FIG6, the aforementioned step of controlling the switch module to switch to the second operating state may include: sending a third control signal to the energy storage converter; the third control signal is used to instruct the energy storage converter to control the corresponding battery management system in the energy storage submodule to send a fourth control signal to the first switch and the second switch.

[0099] The fourth control signal is used to control the corresponding second switch to switch to the on state; it is also used to control the corresponding first switch to switch to the off state when the corresponding second switch is switched to the on state.

[0100] In this embodiment of the application, when the control device determines that the energy storage system has switched from a hot standby state to a charging and discharging state, it generates a third control signal and sends the third control signal to the energy storage converter of each energy storage submodule.

[0101] Taking the energy storage submodule SM3131 as an example, after the energy storage converter of the energy storage submodule receives the third control signal, it instructs the corresponding battery management system to generate a fourth control signal through the communication bus inside the energy storage submodule, and sends the fourth control signal to the first switch and the second switch of the same energy storage submodule.

[0102] In this embodiment, the battery management system controls the second switch K2 to switch from the off state to the on state based on the fourth control signal sent to the second switch K2. At this time, the first switch K1 is still in the on state (when the energy storage system was in a hot standby state before).

[0103] In this embodiment, since the energy storage system is preparing to switch to hot standby mode, the current in the circuit approaches zero. Therefore, when the second switch K2 switches to the on state, the electric arc between the contacts is relatively weak and has little impact on the electrical life of the second switch K2.

[0104] After the second switch K2 in the energy storage submodule is turned on, the protection device is short-circuited because the branch where the first switch K1 is located and the branch where the second switch K2 is located are connected in parallel. However, the current in the circuit is small at this time. Based on the fourth control signal sent to the first switch K1, the battery management system drives the first switch K1 to switch to the off state. At this time, the electric arc between the contacts is relatively weak and has little impact on the electrical life of the second switch K2.

[0105] In this embodiment, after the battery management system completes the control of the first switch K1 and the second switch K2, it sends the relevant status of the switching completion to the energy storage converter. The energy storage converter reports the relevant information of the switching completion to the control device, and the control device issues relevant control commands on the charging and discharging status to each energy storage submodule in the energy storage system, controlling the energy storage system to switch to the charging and discharging state.

[0106] In some embodiments, the protection device may include multiple resistors, each resistor being connected in series with a corresponding switch to form multiple branches, all of which are connected in parallel with the second switch K2. The battery management system can, based on the upper limit of the time each resistor can withstand the impact of the energy storage converter's operating current, control the switches corresponding to each resistor to conduct at different times when the hot standby time is long, thereby connecting the corresponding resistor between the energy storage converter and the battery cell. The control method refers to the control method of the first switch K1 and the second switch K2, and is not specifically limited here.

[0107] This application provides a control and protection method. The energy storage converter in the energy storage submodule receives a third control signal. Based on the third control signal, the energy storage converter instructs the corresponding battery management system to send a fourth control signal to the first switch and the second switch. The second switch is controlled to turn on first, and then the first switch is controlled to turn on, disconnecting the protection device. This ensures that the electrical connection between the energy storage converter and the battery cell is not interrupted when the energy storage system switches operating modes, and the protection device is smoothly disconnected. This avoids the loss generated by the protection device when the energy storage submodule is charging and discharging normally, and also reduces the generation of arc during the switching on and off process, extends the life of the switch, and ensures the working stability and reliability of the energy storage system in the charging and discharging state.

[0108] In some embodiments, as shown in FIG7, the switch module 314 further includes a third switch K3.

[0109] The method may further include: sending a fifth control signal to the energy storage converter of each energy storage submodule when the energy storage system is powered on; the fifth control signal is used to instruct the corresponding third switch to switch to the on state.

[0110] In this embodiment of the application, as shown in FIG7, the switch module may further include a third switch K3, for example, between the positive terminal of the battery cell connected to the branch where the first switch K1 is located and the energy storage converter connected to the second switch K2, and the third switch K3 is connected in series between the negative terminal of the battery cell and the energy storage converter; or, in some embodiments, between the negative terminal of the battery cell connected to the branch where the first switch K1 is located and the energy storage converter connected to the second switch K2, and the third switch K3 is connected in series between the positive terminal of the battery cell and the energy storage converter.

[0111] In this embodiment, after the energy storage system is powered on, when the control device determines that the energy storage system is ready to enter the charging and discharging state, the control device sends a fifth control signal to the energy storage converter in each energy storage submodule, instructing the energy storage converter to control the third switch K3 to switch to the on state, and sends a third control signal to the energy storage converter, instructing the energy storage converter to control the second switch K2 to switch to the on state, and controls the first switch K1 to remain in the off state.

[0112] In this embodiment of the application, after the energy storage system is powered on, when the control device determines that the energy storage system is ready to enter the hot standby state, the control device sends a fifth control signal to the energy storage converter in each energy storage submodule, instructing the energy storage converter to control the third switch K3 to switch to the on state, and sends a first control signal to the energy storage converter to control the first switch K1 to switch to the on state, and controls the second switch K2 to remain in the off state.

[0113] In this embodiment of the application, when it is determined that the energy storage system is switching from the charging and discharging state to the hot standby state, the third switch K3 remains in the conducting state, the control device sends a first control signal to the energy storage converter in each energy storage submodule, and controls the first switch K1 to switch to the conducting state, and then the second switch K2 switches to the off state.

[0114] In this embodiment, when the energy storage system switches from hot standby to charging / discharging state, the third switch K3 remains in the conducting state. The control device sends a third control signal to the energy storage converter in each energy storage submodule, and after controlling the second switch K2 to switch to the conducting state, the first switch K1 switches to the off state.

[0115] It should be noted that if a fault is detected in the energy storage converter or a battery cell, the first switch K1, the second switch K2, and the third switch K3 between the energy storage converter and the battery cell can be disconnected to achieve electrical isolation of the fault.

[0116] This application provides a control and protection method. The switching module also includes a third switch, which provides electrical isolation between the energy storage converter and the battery cell. It can also serve as a redundancy for the second switch, replacing it to perform related functions when the second switch fails, thereby improving the reliability of the energy storage system.

[0117] In some embodiments, as shown in Figures 6 and 7, the energy storage converter includes multiple switching transistors, and the control terminals of the multiple switching transistors are respectively connected to a control device.

[0118] In this embodiment, the energy storage converter includes multiple switching transistors, as shown in Figures 6 and 7. The following description uses an energy storage converter comprising a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, and a fourth switching transistor Q4 as an example. These multiple switching transistors can be NMOS transistors. The drains of the first switching transistor Q1 and the second switching transistor Q2 are connected and then connected to a battery cell via a first switch and a second switch. The source of the drain of the first switching transistor Q1 is connected to the drain of the third switching transistor Q3, and the source of the second switching transistor Q2 is connected to the drain of the fourth switching transistor Q4. The sources of the third switching transistor Q3 and the fourth switching transistor Q4 are connected and then connected to the battery cell, or connected to the battery cell via a third switch. The gate (or control terminal) of each switching transistor is connected to a control device.

[0119] In some embodiments, before the switching module switches to the first operating state, the method may further include: when it is determined that the energy storage system is switching from a charging / discharging state to a hot standby state, sending a sixth control signal to the energy storage converter in each energy storage submodule; the sixth control signal is used to instruct the corresponding plurality of switching transistors to switch to the off state.

[0120] In this embodiment, when the control device determines that the energy storage system is switching from a charging / discharging state to a hot standby state, the control device sends a sixth control signal to the energy storage converter in each energy storage submodule of the energy storage system to control the switching transistors in each energy storage submodule to lock out. In this case, the pulse width modulation (PWM) signal is no longer generated inside the energy storage converter, the common-mode voltage caused by the high-frequency switching of each switching transistor in the energy storage converter disappears, and the reactive power jitter on the reactor and the micro-charging / discharging current at the battery terminal will be suppressed.

[0121] Furthermore, based on the aforementioned embodiments, after the control device controls the first switch in each energy storage submodule to be turned on and the second switch to be turned off, the energy storage system enters a hot standby state. In this way, locking the switching transistors before switching them off can avoid the large instantaneous power during switching, and can also ensure that if the control of each switching transistor fails, the common-mode voltage generated during the hot standby of the energy storage system will not affect the battery cell side.

[0122] In some embodiments, after the switching module switches to the second operating state, the method may further include: when it is determined that the energy storage system is switching from a hot standby state to a charge / discharge state, sending a seventh control signal to the energy storage converter in each energy storage submodule; the seventh control signal is used to instruct the corresponding plurality of switching transistors to switch to the on state.

[0123] In this embodiment, when the control device determines that the energy storage system is switching from a hot standby state to a charging / discharging state, the control device first controls the second switch in each energy storage submodule to be turned on and the first switch to be turned off based on the second control signal. Further, it sends a seventh control signal to the respective energy storage converter in each energy storage submodule to unlock the switching transistors in each submodule, allowing the energy storage system to enter the charging / discharging state. Thus, switching the switches before unlocking the transistors avoids the system experiencing large instantaneous power during switching, ensuring that the normal charging and discharging of the energy storage system is not affected, and improving the reliability of the energy storage system during operation.

[0124] This application provides a control and protection method. When the energy storage system switches to a hot standby state, it controls the locking of each switch tube of the energy storage converter in each energy storage submodule, disconnects the high-frequency switching action of each switch tube, but the energy storage converter does not go into hibernation, and then switches the working state of the switch module. When the energy storage system switches to a charge / discharge state, it first switches the working state of the switch module, and then controls each switch tube of the device to conduct. This can suppress the generation of common-mode signals from the source, thereby reducing the impact on the life of individual battery cells, extending battery life, and also enabling the energy storage system to respond in a shorter time when switching to a charge / discharge state, reducing response delay.

[0125] In some embodiments, as shown in Figures 8 and 9, the energy storage system further includes a filter module 315; wherein the filter module 315 is connected between the switch module 314 and the energy storage converter 311.

[0126] In this embodiment of the application, as shown in Figures 8 and 9, the filter module 315 is connected between the energy storage converter 311 and the switch module 314. The positive and negative terminals of the battery cell 313 are connected to the DC input terminal of the energy storage converter 311 via the DC-side switch module 314 and the filter module 315.

[0127] In this embodiment, the filtering module 315 can be used to filter the high-frequency current generated by the common-mode voltage generated by the high-frequency switch of the energy storage converter, thereby reducing the current surge borne by the protection device.

[0128] This application provides an energy storage system in which a filter module is connected between the energy storage converter and the switching module. This reduces the impact of the high-frequency current generated by the energy storage converter during operation on the protection devices and battery cells, thereby improving the safety and stability of the energy storage system.

[0129] In another embodiment of this application, as shown in FIG1, a control device 4 is provided. The control device 4 is disposed in an energy storage system, which includes multiple energy storage sub-modules connected in series. Each energy storage sub-module includes an energy storage converter, a protection device, and a battery cell. The protection device is disposed between the energy storage converter and the battery cell. The control device 4 is used to determine whether the energy storage system switches from a charging / discharging state to a hot standby state. When the energy storage system is in the hot standby state, the energy storage converter generates a resonant current during operation. The control device is connected between the energy storage converter and the battery cell to absorb the resonant current generated by the operation of the energy storage converter. The control device controls the energy storage system to switch to the hot standby state.

[0130] In some embodiments, the control device 4 is further configured to determine that the energy storage system switches from a hot standby state to a charge / discharge state; control the protection device to disconnect from the corresponding energy storage converter and the corresponding battery cell, and connect the energy storage converter to the battery cell, wherein the energy storage converter is used to output electrical energy to the battery cell or receive electrical energy output by the battery cell; and control the energy storage system to switch to the charge / discharge state.

[0131] In some embodiments, as shown in FIG6, the energy storage system further includes a switch module 314, one end of which is connected to the energy storage converter 311, and the other end of which is connected to the protection device 312 and the battery cell 313.

[0132] In some embodiments, the control device 4 is further configured to control the switch module to switch to a first operating state and connect the protection device between the energy storage converter and the battery cell when it is determined that the energy storage system is switching from a charging / discharging state to a hot standby state.

[0133] In some embodiments, the control device 4 is further configured to control the switch module to switch to a second operating state when it is determined that the energy storage system is switching from a hot standby state to a charge / discharge state, thereby disconnecting the protection device from the corresponding energy storage converter and the corresponding battery cell.

[0134] In some embodiments, as shown in FIG6, the switch module 314 includes a first switch K1 and a second switch K2; the first switch K1 is connected in series with the protection device, and the branch where the first switch K1 is located and the second switch K2 are respectively connected between the energy storage converter 311 and the battery cell 313.

[0135] In some embodiments, the control device 4 is further configured to control the switch module to switch to a first working state or a second working state by controlling the first switch and the second switch to be turned on or off.

[0136] In some embodiments, the control device 4 is further configured to send a first control signal to the energy storage converter; the first control signal is configured to instruct the energy storage converter to control the corresponding battery management system in the energy storage submodule to send a second control signal to the first switch and the second switch; wherein the second control signal is configured to control the corresponding first switch to switch to the on state; and is further configured to control the corresponding second switch to switch to the off state when the corresponding first switch is switched to the on state.

[0137] In some embodiments, the control device 4 is further configured to send a third control signal to the energy storage converter; the third control signal is configured to instruct the energy storage converter to control the corresponding battery management system in the energy storage submodule to send a fourth control signal to the first switch and the second switch; wherein, the fourth control signal is configured to control the corresponding second switch to switch to the on state; and is further configured to control the corresponding first switch to switch to the off state when the corresponding second switch is switched to the on state.

[0138] In some embodiments, as shown in FIG7, the switch module further includes a third switch K3.

[0139] In some embodiments, the control device 4 is further configured to send a fifth control signal to the energy storage converter of each energy storage submodule when the energy storage system is powered on; the fifth control signal is configured to instruct the corresponding third switch to switch to the on state.

[0140] In some embodiments, as shown in FIG7, the energy storage converter includes multiple switching transistors, and the control terminals of the multiple switching transistors are respectively connected to a control device.

[0141] In some embodiments, the control device 4 is further configured to send a sixth control signal to the energy storage converter in each energy storage submodule before the switching module switches to the first operating state, provided that the energy storage system is determined to switch from a charging / discharging state to a hot standby state; the sixth control signal is configured to instruct the corresponding plurality of switching transistors to switch to the off state.

[0142] In some embodiments, the control device 4 is further configured to send a seventh control signal to the energy storage converter in each energy storage submodule after the switching module switches to the second operating state and the energy storage system is determined to switch from a hot standby state to a charge / discharge state; the seventh control signal is used to instruct the corresponding plurality of switching transistors to switch to the on state.

[0143] This application provides a control device installed in an energy storage system. The energy storage system includes multiple energy storage sub-modules connected in series. Each sub-module includes a protection device, an energy storage converter, and a battery cell. When the energy storage system is determined to switch from a charging / discharging state to a hot standby state, the control device controls the protection device to connect between the energy storage converter and the battery cell, and then controls the energy storage system to switch to the hot standby state. In the hot standby state, the protection device can absorb the resonant current generated by the high-frequency switching of the energy storage converter, blocking the high-frequency components transmitted from the energy storage converter to the battery cell. This prevents the battery cell from being in a micro-circulation charging / discharging state due to the resonant current, thereby protecting the battery from micro-circulation damage and extending the battery's lifespan.

[0144] This application also provides a computer program product, which includes a computer program or instructions that, when executed by a processor, implement some or all of the steps in the above-described method. This computer program product can be implemented specifically through hardware, software, or a combination thereof. In one optional embodiment, the computer program product is specifically embodied in a computer storage medium; in another optional embodiment, the computer program product is specifically embodied in a software product, such as a software development kit (SDK), etc.

[0145] The control and protection methods, control devices, and program products provided in the embodiments of this application will be described in detail below, in conjunction with specific application scenarios.

[0146] Electrochemical energy storage systems typically operate on a timed basis according to scheduling requirements, either storing or releasing energy, with the remaining time in hot standby mode and a small amount of time under maintenance. Operating time accounts for approximately 15%–35% of the total time, maintenance time for approximately 1%, and hot standby time for approximately 65%–85%. Current energy storage systems are typically configured for hot standby with both active and reactive power at zero. Because the PCS continues to operate normally during hot standby, the switching of the IGBTs generates common-mode voltage, creating reactive power fluctuations on associated reactive components. Figure 3 shows the reactive power results from computer simulation; the release and absorption are interleaved, with a small average value, but its long-term presence still causes unnecessary loss of battery life. Preliminary analysis suggests that approximately 400 cycles are lost over the entire lifespan of the energy storage unit, which is unacceptable.

[0147] The reason for the aforementioned loss of battery cycle life due to reactive power is that the PCS continues to operate in hot standby mode, causing the battery to be in a state of continuous micro-charging and micro-discharging, resulting in wasted battery life.

[0148] Based on this, the present application provides a control and protection method, control device and program product. By improving the strategy of the control and protection device of the energy storage system, the pre-charge resistor (protection device) in the DC side circuit is put into operation when the energy storage system is in hot standby. The pre-charge resistor limits the waste of battery cycle life caused by continuous reactive power fluctuation.

[0149] In this embodiment of the application, when the electrochemical energy storage unit is in hot standby mode, the main controller of the electrochemical energy storage unit issues a command to connect the DC side pre-charge resistor to the circuit, thereby reducing the energy entering the battery. Under the same conditions as in Figure 3, the battery current is reduced by several orders of magnitude, as shown in Figure 4, which significantly reduces the unnecessary cycle life loss of the battery.

[0150] In this embodiment of the application, the simplified topology of the energy storage system is shown in Figure 1, where SM is a submodule and the serial number indicates the number of the submodule cascade sequence. After each phase of the system connects multiple submodules in series to reach the grid voltage, they are connected to the grid through a reactor. Each submodule contains a battery cluster (battery cell) and a PCS. The battery cell provides / absorbs energy for the system, and the PCS is responsible for converting the DC power of the battery into AC power.

[0151] The main control units involved in the implementation of the energy storage system are the battery management unit and the control and protection device. The battery management unit is the largest management unit of the submodule battery cluster, responsible for controlling the DC-side precharge circuit and communicating with the PCS in the submodule. The control and protection device is the control center of all PCS in the system and communicates with all PCS.

[0152] In the embodiments of this application, the principle is as shown in steps 1)-3).

[0153] 1) The topology of the power module of the energy storage converter is shown in Figures 6-9. The pre-charge circuit is controlled by switches K1 and K2. When the unit is running normally, K2 and K3 are closed and K1 is open.

[0154] 2) When the energy storage system enters the hot standby state, the control and protection device recognizes that the system is about to enter the hot standby state and sends a hot standby command to all PCS. After receiving the command, the PCS sends a request to close K1 to the corresponding battery management system. The battery management system closes K1 and opens K2 in sequence. After all energy storage submodules have closed K1 and opened K2, the system enters the hot standby state.

[0155] 3) When the system is charging or discharging, the control and protection device sends a command to exit hot standby to all PCS. Each PCS sends a request to disconnect K1 to the battery management system. The battery management system then sequentially closes K2, disconnects K1, and sends the command. After all energy storage submodules have their K2 connections closed, the control and protection device controls the energy storage system to enter the charging and discharging state.

[0156] In this embodiment of the application, the control process of the power module in the energy storage submodule shown in Figures 6-9 includes the following steps (1)-(6).

[0157] (1) The energy storage system enters hot standby mode.

[0158] (2) Send a blocking signal to the PCS, and the IGBT blocks.

[0159] (3) Close K2, open K1, and connect the pre-charge resistor.

[0160] (4) The PCS receives the scheduling signal.

[0161] (5) Close K1 and open K2 to cut off the pre-charge resistor.

[0162] (6) Unlock the PCS and the energy storage system enters the charging and discharging state.

[0163] Thus, in this embodiment, by improving the control strategy of the main control of the electrochemical energy storage unit (energy storage system), a pre-charge resistor function is added for hot standby. Furthermore, the bypass pre-charge resistor signal is associated with unit operation; when the unit starts operating, all DC-side pre-charge resistors are bypassed immediately, ensuring the unit is in normal operating condition. The hot standby control program is also optimized: during hot standby, all stages of IGBTs (switching transistors of the energy storage converter) are locked out, and on this basis, the DC-side pre-charge resistors are closed, increasing the battery circuit impedance and limiting power fluctuations to the bus capacitor. This reduces the current entering the battery, lowers the battery's charge / discharge capacity during hot standby, and reduces capacity loss in the hot standby state.

[0164] It should be understood that the phrases "one embodiment," "an embodiment," or "some embodiments" mentioned throughout the specification mean that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment," "in one embodiment," or "in some embodiments" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above-described embodiments are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments. The descriptions of the various embodiments above tend to emphasize the differences between the various embodiments; their similarities or commonalities can be referred to mutually, and for the sake of brevity, they will not be repeated here.

[0165] It should also be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0166] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0167] The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments.

[0168] The features disclosed in the several product embodiments provided in this application can be arbitrarily combined without conflict to obtain new product embodiments.

[0169] The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined without conflict to obtain new method or device embodiments.

[0170] The above are merely preferred embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A control and protection method, characterized in that, An application is made in an energy storage system, the energy storage system comprising multiple energy storage sub-modules connected in series; each energy storage sub-module includes an energy storage converter, a protection device, and a battery cell, the protection device being disposed between the energy storage converter and the battery cell; the method includes: determining that the energy storage system is switching from a charge / discharge state to a hot standby state; wherein, when the energy storage system is in the hot standby state, the energy storage converter generates a resonant current during operation; controlling the protection device to connect between the energy storage converter and the battery cell, the protection device being used to absorb the resonant current generated by the operation of the energy storage converter; and controlling the energy storage system to switch to the hot standby state.

2. The method according to claim 1, characterized in that, The method further includes: determining that the energy storage system switches from a hot standby state to a charge / discharge state; controlling the protection device to disconnect from the corresponding energy storage converter and the corresponding battery cell, wherein the energy storage converter is connected to the battery cell, and the energy storage converter is used to output electrical energy to the battery cell or receive electrical energy output by the battery cell; and controlling the energy storage system to switch to a charge / discharge state.

3. The method according to claim 2, characterized in that, The energy storage system also includes a switching module, one end of which is connected to the energy storage converter, and the other end of which is connected to the protection device and the battery cell. The control of the protection device connecting between the energy storage converter and the battery cell includes: when it is determined that the energy storage system is switching from a charging / discharging state to a hot standby state, the control switch module switches to a first operating state to connect the protection device between the energy storage converter and the battery cell; or, the control of the protection device disconnecting from the corresponding energy storage converter and the corresponding battery cell includes: when it is determined that the energy storage system is switching from a hot standby state to a charging / discharging state, the control switch module switches to a second operating state to disconnect the protection device from the corresponding energy storage converter and the corresponding battery cell.

4. The method according to claim 3, characterized in that, The switching module includes a first switch and a second switch; the first switch is connected in series with the protection device, and the branch where the first switch is located and the second switch are respectively connected between the energy storage converter and the battery cell; the method further includes: controlling the switching module to switch to the first working state or the second working state by controlling the first switch and the second switch to turn on or off.

5. The method according to claim 4, characterized in that, Switching the control switch module to the first operating state includes: sending a first control signal to the energy storage converter; the first control signal is used to instruct the energy storage converter to control the corresponding battery management system in the energy storage submodule to send a second control signal to the first switch and the second switch; wherein, the second control signal is used to control the corresponding first switch to switch to the on state; and is also used to control the corresponding second switch to switch to the off state when the corresponding first switch is switched to the on state.

6. The method according to claim 4, characterized in that, Switching the control switch module to the second operating state includes: sending a third control signal to the energy storage converter; the third control signal is used to instruct the energy storage converter to control the corresponding battery management system in the energy storage submodule to send a fourth control signal to the first switch and the second switch; wherein, the fourth control signal is used to control the corresponding second switch to switch to the on state; and is also used to control the corresponding first switch to switch to the off state when the corresponding second switch is switched to the on state.

7. The method according to any one of claims 4-6, characterized in that, The switching module further includes a third switch; the method further includes: when the energy storage system is powered on, sending a fifth control signal to the energy storage converter of each energy storage submodule; the fifth control signal is used to instruct the corresponding third switch to switch to the on state.

8. The method according to any one of claims 1-6, characterized in that, The energy storage converter includes multiple switching transistors, the control terminals of which are respectively connected to a control device. Before the switching module switches to the first operating state, the method further includes: when it is determined that the energy storage system is switching from a charging / discharging state to a hot standby state, sending a sixth control signal to the energy storage converter in each of the energy storage sub-modules; the sixth control signal is used to instruct the corresponding multiple switching transistors to switch to the off state. After the switching module switches to the second operating state, the method further includes: when it is determined that the energy storage system is switching from a hot standby state to a charging / discharging state, sending a seventh control signal to the energy storage converter in each of the energy storage sub-modules; the seventh control signal is used to instruct the corresponding multiple switching transistors to switch to the on state.

9. A control device, characterized in that, The control device is installed in the energy storage system, which includes multiple energy storage sub-modules connected in series. Each energy storage sub-module includes an energy storage converter, a protection device, and a battery cell. The protection device is located between the energy storage converter and the battery cell. The control device is used to determine when the energy storage system switches from a charging / discharging state to a hot standby state. When the energy storage system is in the hot standby state, the energy storage converter generates a resonant current during operation. The control device connects the protection device between the energy storage converter and the battery cell, and absorbs the resonant current generated by the energy storage converter. The control device then switches the energy storage system to the hot standby state.

10. A program product comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the method of any one of claims 1 to 8.

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