Energy storage system, control method, control device and energy storage equipment

Abstract

This application provides an energy storage system, control method, control device, and energy storage equipment. It includes: multiple battery clusters, multiple hybrid switches, and a power converter; each battery cluster corresponds to a hybrid switch; each battery cluster is connected to one end of the power converter via a corresponding hybrid switch, and the other end of the power converter is connected to an AC power source; the hybrid switches are used to turn on when the corresponding battery cluster is not in a state imbalance, connecting the battery cluster to the power converter; and to turn off when the corresponding battery cluster is in a state imbalance, disconnecting the connection between the battery cluster and the power converter. This method enables the energy storage system to control the charging and discharging of individual battery clusters during the charging and discharging process.

Description

Technical Field

[0001] This application relates to energy storage technology, and more particularly to an energy storage system, control method, control device, and energy storage equipment. Background Technology

[0002] Large-capacity energy storage systems are widely used in the energy storage field for both energy storage and release. These systems typically consist of multiple battery clusters connected in parallel. For example, one battery cluster and one contactor form a parallel branch, and multiple parallel branches are connected to the AC grid via a power conversion system (PCS). The PCS controls the charging and discharging of each battery cluster.

[0003] This type of energy storage system has the problem that it cannot control the charging and discharging of individual battery clusters during the charging and discharging process. Summary of the Invention

[0004] This application provides an energy storage system, control method, control device, and energy storage equipment to enable the energy storage system to control the charging and discharging of a single battery cluster during the charging and discharging process.

[0005] In a first aspect, embodiments of this application provide an energy storage system, including: multiple battery clusters, multiple hybrid switches, and a power converter;

[0006] The battery clusters correspond one-to-one with the hybrid switches; the battery clusters are connected to one end of the power converter through the corresponding hybrid switches, and the other end of the power converter is connected to an AC power source.

[0007] The hybrid switch is configured to turn on when the corresponding battery cluster is not in a state imbalance, so as to connect the battery cluster to the power converter; and to turn off when the corresponding battery cluster is in a state imbalance, so as to disconnect the connection between the battery cluster and the power converter.

[0008] Optionally, the hybrid switch includes: a first switch and a second switch;

[0009] The first switch and the second switch are connected in parallel.

[0010] Optionally, the hybrid switch is turned on when the corresponding battery cluster is not in a state imbalance, specifically including:

[0011] The second switch is turned on when the corresponding battery cluster is not in an unbalanced state, and the first switch is turned on after the second switch is turned on, and the second switch is turned off after the first switch is turned on, so that the hybrid switch is turned on.

[0012] Optionally, the hybrid switch disconnects when the corresponding battery clusters are in an unbalanced state, specifically including:

[0013] When the corresponding battery cluster experiences an imbalance in its state, the second switch is activated, and after the second switch is activated, the first switch is deactivated, and after the first switch is deactivated, the second switch is deactivated, thereby deactivating the hybrid switch.

[0014] Optionally, the first switch includes a mechanical switch, and the second switch includes a semiconductor switch.

[0015] Optionally, the battery cluster includes: multiple battery packs;

[0016] The multiple battery packs are connected in series.

[0017] Optionally, the battery pack includes multiple battery cells;

[0018] The multiple battery cells are connected in series.

[0019] Optionally, the battery packs have the same specifications.

[0020] Optionally, the power converter is configured to convert AC power from the AC power source into DC power when a charging command is received, so as to charge the battery cluster connected to the power converter; and to convert DC power from the battery cluster connected to the power converter into AC power when a discharging command is received, and output it to the AC power source.

[0021] Optionally, the energy storage system further includes: multiple battery management units;

[0022] The battery management unit corresponds one-to-one with the battery cluster; the battery management unit is used to detect the status of the corresponding battery cluster and report the status.

[0023] In a second aspect, embodiments of this application provide a control method for an energy storage system, applied to an energy storage system as described in any of the first aspects, comprising: detecting the state of multiple battery clusters;

[0024] When the plurality of battery clusters are not in an unbalanced state, the hybrid switch corresponding to the plurality of battery clusters is turned on to charge or discharge the plurality of battery clusters; and when the state of any battery cluster is unbalanced, the hybrid switch corresponding to that battery cluster is turned off to stop charging or discharging that battery cluster.

[0025] Optionally, turning on the hybrid switch corresponding to the plurality of battery clusters specifically includes:

[0026] The second switch is turned on, and after the second switch is turned on, the first switch is turned on, and after the first switch is turned on, the second switch is turned off, so that the hybrid switch is turned on.

[0027] Optionally, disconnecting the hybrid switch corresponding to the battery cluster specifically includes:

[0028] The second switch is turned on, and after the second switch is turned on, the first switch is turned off, and after the first switch is turned off, the second switch is turned off, so that the hybrid switch is turned off.

[0029] Optionally, the method further includes:

[0030] Based on the state of the battery cluster detected by the battery management unit, it is determined whether the battery cluster is experiencing state imbalance.

[0031] Optionally, the method further includes:

[0032] A charging command is sent to the power converter to convert the AC power from the AC power source into DC power to charge the battery cluster connected to the power converter; or, a discharging command is sent to the power converter to convert the DC power output from the battery cluster connected to it into AC power and output it to the AC power source.

[0033] Thirdly, embodiments of this application provide a control device for an energy storage system, applied to an energy storage system as described in any of the first aspects, comprising:

[0034] The detection module is used to detect the status of multiple battery clusters;

[0035] The control module is configured to, when the plurality of battery clusters are not in a state imbalance, turn on the hybrid switch corresponding to the plurality of battery clusters to charge or discharge the plurality of battery clusters; and, when the state of any battery cluster is imbalanced, turn off the hybrid switch corresponding to that battery cluster to stop charging or discharging that battery cluster.

[0036] Fourthly, embodiments of this application provide an energy storage device, including an energy storage system as described in any of the first aspects, and a control device as described in the third aspect.

[0037] The energy storage system, control method, control device, and energy storage equipment provided in this application embodiment use a hybrid switch instead of a contactor. This allows the hybrid switch to be disconnected when the state of the battery cluster becomes unbalanced, thereby disconnecting the battery cluster from the power converter and stopping charging or discharging the battery cluster. This enables the energy storage system to control the charging and discharging of individual battery clusters during the charging and discharging process. Attached Figure Description

[0038] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0039] Figure 1 A schematic diagram illustrating an application scenario provided in an embodiment of this application;

[0040] Figure 2 This is a schematic diagram of the structure of an energy storage system provided in an embodiment of this application;

[0041] Figure 3 This is a schematic diagram of another energy storage system provided in an embodiment of this application;

[0042] Figure 4 This is a schematic diagram of the structure of a third energy storage system provided in an embodiment of this application;

[0043] Figure 5 This is a schematic diagram of the structure of the fourth energy storage system provided in the embodiments of this application;

[0044] Figure 6 A flowchart illustrating a control method for an energy storage system provided in an embodiment of this application;

[0045] Figure 7 A flowchart illustrating the control method for a second energy storage system provided in this application embodiment;

[0046] Figure 8 This is a schematic diagram of the structure of a control device for an energy storage system provided in an embodiment of this application.

[0047] Explanation of reference numerals in the attached figures:

[0048] 1: Battery cluster; 11: Battery pack; 2: Hybrid switch; 21: First switch; 22: Second switch; 3: Power converter.

[0049] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0050] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0051] Figure 1 This is a schematic diagram illustrating an application scenario provided in an embodiment of this application, such as... Figure 1 As shown, the specific application scenario of this application is large-capacity energy storage.

[0052] Large-capacity energy storage systems are widely used in the field of energy storage, and can be used for the storage and release of energy. For example, large-capacity energy storage systems can store excess electrical energy during off-peak hours and release it during peak hours, playing a role in peak shaving and valley filling, thereby reducing the operating costs of the power grid.

[0053] How to increase the capacity of energy storage systems and achieve long-term energy storage is an urgent problem to be solved.

[0054] Currently, there are four main methods to increase the capacity of energy storage systems:

[0055] (1) Increase the capacity of the battery cells. For example, the current maximum capacity of a battery cell is 1130 Ah, which is only 3.6 times higher than the widely used 314 Ah battery cell.

[0056] This method is constrained by the development progress of large-capacity battery cells, making it difficult to increase capacity.

[0057] (2) In response to the problems of the first method, another method to increase the capacity of the energy storage system is proposed. Increase the number of battery packs connected in series in the battery cluster. For example, the commonly used battery cluster consists of 8 battery packs connected in series, each battery pack consists of 52 cells connected in series. Taking the voltage of each cell as 3.6V as an example, the total voltage of the battery cluster can be close to 1500V. If the number of battery packs connected in series is further increased, the voltage level of the energy storage system needs to be increased, and electrical components with higher withstand voltage values ​​need to be used.

[0058] This method may increase the cost of electrical components and also poses a risk of high voltage.

[0059] (3) In response to the problems of the above two methods, a third method to improve the capacity of energy storage system is proposed.

[0060] Figure 2 This is a schematic diagram of an energy storage system provided in an embodiment of this application. Figure 2As shown, the system includes n battery clusters and n contactors; each battery cluster and contactor corresponds one-to-one; one battery cluster and one contactor form a parallel branch, and multiple parallel branches are connected to the AC grid side through a PCS. The PCS controls the charging or discharging of each battery cluster. One battery cluster consists of m battery packs connected in series. One battery pack consists of 52 cells connected in series. Each cell has a rated power (P). In this configuration, the voltage and current of the battery clusters are typically quite high. When the contactor disconnects under load, an electric arc may form between the contactor's switching contacts, damaging the device and affecting the safety and reliability of the energy storage system. Therefore, the contactor cannot frequently disconnect under load, and it cannot control the disconnection or connection of a single battery cluster to the PCS during charging and discharging.

[0061] This method overcomes the shortcomings of the two methods mentioned above, and can also reduce the current of each battery cluster, thereby improving the efficiency of the battery cluster and reducing heat generation.

[0062] However, this type of energy storage system has the problem of not being able to control the charging and discharging of individual battery clusters during the charging and discharging process. After long-term charging and discharging, the energy storage system may face performance degradation or capacity decay due to imbalances between battery clusters.

[0063] Therefore, how to achieve charge and discharge control of individual battery clusters during the charging and discharging process in energy storage systems has become an urgent problem to be solved.

[0064] (4) Targeting Figure 2 To address the shortcomings of the energy storage system shown, an alternative energy storage system is proposed.

[0065] Figure 3 This is a schematic diagram of another energy storage system provided in an embodiment of this application. Figure 3 As shown, it includes n battery clusters, n contactors, and n PCS (Power Control System); each battery cluster, contactor, and PCS corresponds one-to-one. One battery cluster, one contactor, and one PCS form a parallel branch, and multiple parallel branches are connected to the AC power grid. One battery cluster consists of m battery packs connected in series. One battery pack consists of 52 cells connected in series. Each battery pack is 1P (Power Output).

[0066] Figure 3 The energy storage system shown can control the charging and discharging of corresponding battery clusters through PCS, achieving individual cluster management and thus solving the impact of inter-cluster imbalance. However, parallel connection of multiple PCS increases the difficulty of AC coupling control and also increases system cost.

[0067] Therefore, how to achieve charge and discharge control of individual battery clusters in an energy storage system without increasing the difficulty of AC coupling control is an urgent problem to be solved.

[0068] In view of this, this application proposes an energy storage system, in Figure 2 Based on the above, by replacing the contactor with a device capable of load-bearing disconnection, the device can be disconnected when the state of the battery cluster becomes unbalanced, thereby breaking the connection between the battery cluster and the PCS and stopping the charging or discharging of the battery cluster. This enables the energy storage system to control the charging and discharging of individual battery clusters during the charging and discharging process. Each battery cluster is connected to the AC side via a DC bus and then through the PCS, eliminating the need for AC coupling control.

[0069] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0070] Figure 4 This is a schematic diagram of the structure of a third type of energy storage system provided in an embodiment of this application. Figure 4 As shown, the energy storage system includes: multiple battery clusters 1, multiple hybrid switches 2, and a power converter 3;

[0071] Battery cluster 1 can be, for example, an integral assembly composed of any unit capable of storing and releasing electrical energy.

[0072] The hybrid switch 2 can be any switch that combines mechanical and semiconductor technologies to enable the connection and disconnection of a load circuit. The hybrid switch 2 can include, for example, any of the following: a mechanical switch combined with a semiconductor switch, a mechanical relay combined with a solid-state relay, a smart circuit breaker combined with a semiconductor switch, a vacuum circuit breaker combined with a semiconductor switch, etc.

[0073] The power converter 3 can be any converter capable of bidirectional conversion, capable of converting direct current to alternating current and vice versa. The power converter 3 can be, for example, a PCS.

[0074] Each battery cluster 1 corresponds one-to-one with a hybrid switch 2. Each battery cluster 1 is connected to one end of a power converter 3 via its corresponding hybrid switch 2, and the other end of the power converter 3 is connected to an AC power source. In charging mode, the power converter 3 converts the AC power from the AC power source into DC power to charge the battery cluster 1. In discharging mode, the power converter 3 converts the DC power released from the battery cluster 1 into AC power and outputs it to the AC power source. Each battery cluster 1 is connected to the AC side via DC power and then through the power converter 3, eliminating the need for AC coupling control.

[0075] The hybrid switch 2 is used to turn on when the corresponding battery cluster 1 is not in a state imbalance, so as to connect the battery cluster 1 to the power converter 3; the power converter 3 can charge or discharge the connected battery cluster 1. Conversely, the hybrid switch 2 is turned off when the corresponding battery cluster 1 is in a state imbalance, so as to disconnect the connection between the battery cluster 1 and the power converter 3. The power converter 3 can then stop charging or discharging the battery cluster 1, thereby enabling the energy storage system to control the charging and discharging of individual battery clusters during the charging and discharging process.

[0076] In summary, the energy storage system provided in this application, by using a hybrid switch instead of a contactor, allows the hybrid switch to be disconnected when the state of the battery cluster becomes unbalanced, thereby disconnecting the battery cluster from the power converter and stopping the charging or discharging of the battery cluster. This enables the energy storage system to control the charging and discharging of individual battery clusters during the charging and discharging process.

[0077] Figure 5 This is a schematic diagram of the structure of a fourth energy storage system provided in an embodiment of this application. Figure 4 Based on the embodiments, the structure of the energy storage system will be described in detail. For example... Figure 5 As shown, in this energy storage system, the hybrid switch 2 includes a first switch 21 and a second switch 22.

[0078] The first switch 21 can be any switch capable of being turned on or off based on a high-level or low-level signal and having mechanical contacts. The first switch 21 typically has low conduction losses. For example, the first switch 21 can include a mechanical switch. A mechanical switch can be any switch that turns a circuit on or off through physical movement based on a high-level or low-level signal, and typically includes metal contacts. Examples include any of the following: a relay, a circuit breaker, a contactor, etc.

[0079] The second switch 22 can be any switch that can be turned on or off based on a high-level or low-level signal and has no mechanical contacts. For example, it can include a semiconductor switch. A semiconductor switch can be any switch that can be turned on based on a high-level or low-level signal, typically with a fast response and without metal contacts. For example, it can be any of the following: a metal-oxide-semiconductor field-effect transistor (MOSFET), also known as a MOS transistor, an insulated-gate bipolar transistor (IGBT), etc.

[0080] The first switch 21 and the second switch 22 are connected in parallel.

[0081] When the battery cluster 1 corresponding to the hybrid switch 2 is not in an unbalanced state, the second switch 22 can be turned on. After the second switch 22 is turned on, the first switch 21 is turned on. After the first switch 21 is turned on, the second switch 22 is turned off so that the hybrid switch 2 is turned on.

[0082] In one example, when the corresponding battery cluster 1 is not in a state imbalance, the second switch 22 is used to receive a high-level signal and the second switch 22 is turned on; after the second switch 22 is turned on, the first switch 21 is used to receive a high-level signal and the first switch 21 is turned on; then, after the first switch 21 is turned on, the second switch 22 is used to receive a low-level signal and the second switch 22 is turned off, so that the hybrid switch 2 is turned on.

[0083] Before the first switch 21 is turned on, the second switch 22 is turned on and used to carry the current. Since the second switch 22 has a fast response and no mechanical contacts, no arcing will occur. After the second switch 22 has been turned on and is stably carrying the current, the first switch 21 is turned on. At this time, since the current has already passed through the second switch 22, the contacts of the first switch 21 will not carry a large current when closed, thus reducing the generation of arcing. Afterwards, once the first switch 21 is fully turned on and can carry the current, the second switch 22 can be turned off, transferring the current completely to the first switch 21. This completes the operation of turning on the hybrid switch 2. By turning on the second switch 22 before the first switch 21 is turned on, arcing on the hybrid switch 2 can be reduced, improving the reliability of the system. When the corresponding battery cluster 1 is not in an unbalanced state, the hybrid switch 2 can be turned on during the charging and discharging process of the energy storage system to connect the corresponding battery cluster 1 to the power converter 3, initiating charging or discharging of the battery cluster 1.

[0084] During normal operation, the hybrid switch 2 is on. At this time, the first switch 21 is on, and the second switch 22 is off, with the load current flowing through the second switch 22. When the state of the battery cluster 1 corresponding to the hybrid switch 2 becomes unbalanced, the hybrid switch 2 needs to switch from the on state to the off state. In this case, the second switch 22 can be turned on first, and after the second switch 22 is turned on, the first switch 21 can be turned off. After the first switch 21 is turned off, the second switch 22 can be turned off, thus turning off the hybrid switch 2.

[0085] In one example, when the state of the battery cluster 1 corresponding to the hybrid switch 2 is unbalanced, the second switch 22 is used to receive a high-level signal and the second switch 22 is turned on; after the second switch 22 is turned on, the first switch 21 is used to receive a low-level signal and the first switch 21 is turned off; then, after the first switch 21 is turned off, the second switch 22 is used to receive a low-level signal and the second switch 22 is turned off, so that the hybrid switch 2 is turned off.

[0086] Before the first switch 21 is opened, the second switch 22 is turned on, providing an additional path for the load current. Therefore, at the instant the first switch 21 is opened, the load current can be transferred to the path of the second switch 22, preventing energy buildup at the ends of the first switch 21 and thus reducing high-voltage arcing. After the first switch 21 is successfully opened, the second switch 22 is opened. Since the second switch 22 has no mechanical contacts, no arc is generated when it is opened. This completes the disconnection operation of the hybrid switch 2. By turning on the second switch 22 before the first switch 21 is opened, providing a new path for the load current, arcing on the hybrid switch 2 can be reduced, improving system reliability. When the corresponding battery cluster 1 experiences state imbalance, the hybrid switch 2 can be disconnected during the charging and discharging process of the energy storage system to disconnect the corresponding battery cluster 1 from the power converter 3, stopping the charging or discharging of that battery cluster 1.

[0087] Furthermore, the battery cluster 1 may include multiple battery packs 11; the multiple battery packs 11 are connected in series. The battery pack 11 may be, for example, an integral assembly composed of any component capable of storing and releasing electrical energy.

[0088] Furthermore, the battery pack 11 may include multiple battery cells; the multiple battery cells are connected in series. A battery cell can be any component capable of storing and releasing electrical energy, and is the basic building block of energy storage, the smallest functional component in an energy storage system. For example, it may include any of the following: lithium-ion battery cells, nickel-metal hydride battery cells, lead-acid battery cells, solid-state battery cells, etc.

[0089] Multiple battery cells can be connected in series to form a battery pack 11, achieving the required voltage. Multiple battery packs 11 connected in series can form a battery cluster 1, which can provide a higher voltage.

[0090] Furthermore, the specifications of multiple battery packs 11 can be the same. Battery packs 11 with the same specifications have similar voltage and capacity characteristics during charging and discharging, which helps to ensure that each battery pack 11 distributes the current evenly in the battery cluster 1 and improves the charging and discharging efficiency of the entire battery cluster 1.

[0091] Furthermore, the power converter 3 can be used to convert AC power from an AC power source into DC power when a charging command is received, so as to charge the battery cluster 1 connected to the power converter 3; this enables the energy storage system to effectively store electrical energy.

[0092] Furthermore, upon receiving a discharge command, the power converter 3 can convert the DC power from the battery cluster 1 connected to the power converter 3 into AC power and output it to an AC power source. This allows the energy storage system to supply power to an AC power source, such as the AC grid.

[0093] Furthermore, the energy storage system also includes: multiple battery management units;

[0094] Each battery management unit corresponds one-to-one with battery cluster 1. The battery management unit is used to detect the status of the corresponding battery cluster 1 and report the status. The battery management unit can be any unit capable of monitoring and managing the performance of the battery cluster. The battery management unit can detect the status of the corresponding battery cluster 1 and report the status to the controller, so that the controller can perform charge and discharge management of the battery cluster 1 according to its status.

[0095] In summary, the energy storage system provided in this application embodiment uses a hybrid switch connected in parallel with a first switch and a second switch. When any battery cluster experiences state imbalance, the second switch in the corresponding hybrid switch is first turned on, providing an additional path for the load current. At the instant the first switch is turned off, the load current can be transferred to the path of the second switch, preventing energy accumulation across the first switch and enabling micro-arc or even arc-free disconnection. Subsequently, the second switch is turned off, achieving load-bearing disconnection of the hybrid switch to disconnect the battery cluster from the power converter, stopping charging or discharging of the battery cluster. This enables the energy storage system to control the charging and discharging of individual battery clusters during the charging and discharging process.

[0096] This application also provides a control method for an energy storage system to control the charging and discharging of the battery clusters in the energy storage system. The execution entity of this method can be, for example, a controller. The controller can be any module capable of outputting control signals, such as high-level or low-level signals, and can be any processing unit such as a microcontroller, embedded processor, or programmable logic device. Optionally, in addition to the processing unit, it may also include peripheral circuit units for the processing unit. The controller can be a module integrated into the energy storage system, or it can be a module independent of the energy storage system.

[0097] Figure 6 This is a flowchart illustrating a control method for an energy storage system provided in an embodiment of this application. This method can be applied to, for example... Figure 4 The energy storage system shown. (As shown in the image) Figure 6 As shown, the method may include, for example, the following steps:

[0098] S601, The controller detects whether multiple battery clusters 1 are in an unbalanced state.

[0099] The controller can directly detect the electrical parameters of each battery cluster 1, such as voltage, current, and temperature, to determine whether multiple battery clusters 1 are in an unbalanced state. Alternatively, the energy storage system may include a battery management unit corresponding to the battery cluster. The battery management unit can detect the electrical parameters of the corresponding battery cluster to detect the state of the battery cluster and report the state to the controller. The controller can then detect whether multiple battery clusters 1 are in an unbalanced state based on the state reported by the battery management unit.

[0100] The controller can detect whether the states of multiple battery clusters 1 are relatively balanced by detecting the states of the battery clusters 1, and then adopt a control strategy to control the charging and discharging of the battery clusters 1.

[0101] If not, proceed to step S602; if any battery cluster 1 experiences a state imbalance, proceed to step S603.

[0102] S602, the controller turns on the hybrid switch 2 corresponding to multiple battery clusters 1 to charge or discharge the multiple battery clusters 1.

[0103] The controller can be connected to the hybrid switch 2, for example, and control the hybrid switch 2 to be turned on by sending a high-level or low-level control signal to the hybrid switch 2.

[0104] When the states of each battery cluster 1 are relatively balanced, it indicates that each battery cluster 1 can perform normal charging and discharging operations. The control can activate the hybrid switch 2 corresponding to multiple battery clusters 1, and the charging and discharging of the energy storage system is controlled only by the power converter 3.

[0105] S603. The controller disconnects the hybrid switch 2 corresponding to the battery cluster 1 to stop charging or discharging the battery cluster 1.

[0106] The controller can be connected to the hybrid switch 2, for example, and control the hybrid switch 2 to open by sending a high-level or low-level control signal to the hybrid switch 2.

[0107] When the state of any battery cluster 1 is unbalanced, the corresponding hybrid switch 2 of the battery cluster 1 is turned off to stop charging or discharging the battery cluster 1, thereby preventing the battery cluster 1 from being overcharged or over-discharged.

[0108] In summary, the energy storage system control method provided in this application can detect the state of each battery cluster and disconnect the corresponding hybrid switch when any battery cluster becomes unbalanced, thereby stopping the charging or discharging of that battery cluster. This enables the energy storage system to control the charging and discharging of individual battery clusters during the charging and discharging process.

[0109] Figure 7 This is a flowchart illustrating a second control method for an energy storage system provided in an embodiment of this application. This method can be applied to, for example... Figure 5 The energy storage system shown. (As shown in the image) Figure 7 As shown, in this embodiment... Figure 6 Based on the embodiments, the control method of the energy storage system is described in detail, and the method includes:

[0110] S701, the controller sends a charging command to the power converter 3 so that the power converter 3 converts the AC power from the AC power source into DC power to charge the battery cluster 1 connected to the power converter 3; or, sends a discharging command to the power converter 3 so that the power converter 3 converts the DC power output from the battery cluster 1 connected to it into AC power and outputs it to the AC power source.

[0111] The controller can establish a communication connection with the power converter 3, and send charging or discharging commands by sending communication commands to the power converter 3.

[0112] The power converter 3 executes the corresponding operation according to the received instruction to charge or discharge the battery cluster connected to the power converter 3.

[0113] S702. The controller determines whether battery cluster 1 is experiencing state imbalance based on the state of battery cluster 1 detected by the battery management unit.

[0114] The controller can establish a communication connection with the battery management unit, and determine whether battery cluster 1 is experiencing state imbalance by receiving the status of battery cluster 1 reported by the battery management unit.

[0115] If not, proceed to step S703; if any battery cluster 1 experiences a state imbalance, proceed to step S704.

[0116] S703, the controller turns on the hybrid switch 2 corresponding to the multiple battery clusters 1 to charge or discharge the multiple battery clusters 1. As an example, turning on the hybrid switch 2 corresponding to the multiple battery clusters 1 may include the following operation:

[0117] The hybrid switch 2 may include, for example, a first switch 21 and a second switch 22. A controller is connected to the control terminals of the first switch 21 and the second switch 22. The controller controls the first switch 21 to be on or off by sending a high-level or low-level control signal to the first switch 21; the controller controls the second switch 22 to be on or off by sending a high-level or low-level control signal to the second switch 22.

[0118] The controller turns on the second switch 22, and after the second switch 22 is turned on, it turns on the first switch 21, and after the first switch 21 is turned on, it turns off the second switch 22 so that the hybrid switch 2 is turned on.

[0119] In one example, the controller sends a high-level signal to the second switch 22, which turns on the second switch 22; after the second switch 22 turns on, it sends a high-level signal to the first switch 21, which turns on the first switch 21; then, it sends a low-level signal to the second switch 22, which turns off the second switch 22, thereby controlling the hybrid switch 2 to turn on.

[0120] S704. The controller disconnects the hybrid switch corresponding to the battery cluster 1 to stop charging or discharging the battery cluster 1. As an example, disconnecting the hybrid switch 2 corresponding to the battery cluster 1 may include the following operations:

[0121] The controller turns on the second switch 22, and after the second switch 22 is turned on, it turns off the first switch 21, and after the first switch 21 is turned off, it turns off the second switch 22, so that the hybrid switch 2 is turned off.

[0122] In one example, the controller sends a high-level signal to the second switch 22, which turns on the second switch 22; after the second switch 22 turns on, it sends a low-level signal to the first switch 21, which turns off the first switch 21; then, it sends a low-level signal to the second switch 22, which turns off the second switch 22, thereby controlling the hybrid switch 2 to turn off.

[0123] In summary, the energy storage system control method provided in this application, by detecting the state of each battery cluster, when any battery cluster experiences state imbalance, first turns on the second switch to transfer the load current carried by the first switch to the second switch, and then turns off the first switch, which can achieve micro-arc or even arc-free disconnection. Subsequently, the second switch is turned off to achieve the disconnection of the hybrid switch corresponding to the battery cluster under load, so as to stop charging or discharging the battery cluster. This method enables the energy storage system to control the charging and discharging of individual battery clusters during the charging and discharging process.

[0124] The following continues with Figure 5 Taking an energy storage system as an example, this paper explains how to design a large-capacity energy storage system.

[0125] Taking an 8-hour battery energy storage system with a design power of 2.5 MW and a capacity of 20 MWh as an example, the DC side of the energy storage system can be composed of 48 battery clusters connected in parallel; each cluster can be composed of 8 battery packs connected in series; each battery pack can be composed of 52 cells connected in series; among them, the cells use cells with a capacity of 314Ah, a rated voltage of 3.2V, and operate at a power of 0.125P, where P is the rated power of the cell.

[0126] The battery cell has a capacity of 314Ah, meaning it can operate at its rated current of 314 amps (A) for 1 hour (h). The rated power P of the battery cell is: rated current * rated voltage = 314A * 3.2V = 1004.8 watts (W). The rated power of the energy storage system is: rated power of the battery cell * number of cells = 1004.8W * 52 * 8 * 48 = 20MW; if each cell operates at 0.125P, then the operating power of the energy storage system is 20MW * 0.125 = 2.5MW.

[0127] Each battery cell has a rated capacity of 314 Ah, which translates to watt-hours (Wh): 314 Ah * 3.2V = 1004.8 Wh. Therefore, the rated capacity of the energy storage system is 1004.8 Wh * 52 * 8 * 48 = 20 MWh. This enables an 8-hour battery energy storage system with an operating power of 2.5 megawatts (MW) and a capacity of 20 MWh.

[0128] In one example, when a 314Ah battery cell is used to make an energy storage system with an operating power of 2.5MW, its capacity is 5MWh, and the battery cell power operates at 0.5P, that is, 2.5MW = 5MWh * 0.5P.

[0129] The energy storage system provided in this application embodiment has a low operating rate of the battery cell (less than 0.5P), which can maintain high energy efficiency of the battery cell and reduce the heat generation of the battery cell, thereby reducing thermal management requirements.

[0130] The 48 battery clusters 1 are connected to the PCS through the corresponding hybrid switch 2, so that the battery clusters 1 can perform DC current collection and then be connected to the AC side through the PCS.

[0131] The hybrid switch 2 is composed of a mechanical switch and a semiconductor switch connected in parallel.

[0132] The control strategy for the energy storage system is as follows:

[0133] (1) When each battery cluster 1 is relatively balanced, for example, when the consistency of the state of charge (SOC) and state of health (SOH) is high, the hybrid switch 2 corresponding to each battery cluster 1 is turned on. When the controller sends a charging command to the power converter 3, the power converter 3 converts the AC power from the AC power source into DC power to charge the battery cluster 1 connected to the power converter 3; or, when the controller sends a discharging command to the power converter 3, the power converter 3 converts the DC power output from the battery cluster 1 connected to it into AC power and outputs it to the AC power source. The charging and discharging of the energy storage system is controlled only by the power converter 3.

[0134] (2) When the battery clusters 1 are unbalanced, for example, the consistency between the state of charge (SOC) and the state of health (SOH) is poor, the battery cluster 1 with less power will reach the charging and discharging cutoff condition first. At this time, the hybrid switch 2 corresponding to the battery cluster 1 will be disconnected to prevent it from being overcharged or over-discharged. This process continues until all battery clusters are fully charged or discharged.

[0135] (3) When the controller detects an abnormality in any battery cluster 1 during charging and discharging, the hybrid switch 2 corresponding to that battery cluster 1 is disconnected. The operating power of the remaining normally functioning battery cluster 1 is adjusted to P1 = 0.125 * 48 / k; where k represents the number of remaining battery cluster 1, i.e., the number of battery cluster 1 connected to the power converter 3 in a charging or discharging state. After the operating power of the remaining normally functioning battery cluster 1 is adjusted, the power of the energy storage system corresponding to each battery cluster 1 connected to the power converter 3 can be maintained. For example, when the controller detects an abnormality in two battery cluster 1 during the operation of the energy storage system, it disconnects the hybrid switch 2 corresponding to these two battery clusters to disconnect these two battery cluster 1 from the power converter 3. At this time, the number of battery cluster 1 connected to the power converter 3 changes from 48 to 46. The operating power of the remaining 46 normally functioning battery clusters is adjusted to P1 = 0.13P, where P represents the rated power of the cell. The energy storage system can still operate at 2.5MW to maintain the original operating power of the energy storage system and improve the stability of the energy storage system operation.

[0136] The energy storage system control method provided in this application embodiment can stop charging or discharging a battery cluster by disconnecting the hybrid switch corresponding to the battery cluster when an imbalance is detected. This allows for charging and discharging control of a single battery cluster during the charging and discharging process. When an abnormality is detected in a battery cluster, disconnecting the hybrid switch corresponding to that battery cluster allows the remaining battery clusters to maintain their original operating power, ensuring the normal operation of the energy storage system.

[0137] Figure 8 A schematic diagram of the structure of a control device for an energy storage system provided in an embodiment of this application is shown below. Figure 8 As shown, the control device includes: a detection module 801 and a control module 802.

[0138] Detection module 801 is used to detect the status of multiple battery clusters 1;

[0139] The control module 802 is used to turn on the hybrid switch 2 corresponding to the multiple battery clusters 1 to charge or discharge the multiple battery clusters 1 when the state of the multiple battery clusters 1 is not unbalanced; and to turn off the hybrid switch 2 corresponding to any battery cluster 1 to stop charging or discharging the battery cluster 1 when the state of any battery cluster 1 is unbalanced.

[0140] One possible implementation is that the control module 802 is specifically used to turn on the second switch 22, and after the second switch 22 is turned on, turn on the first switch 21, and after the first switch 21 is turned on, turn off the second switch 22 so that the hybrid switch 2 is turned on.

[0141] One possible implementation is that the control module 802 is specifically used to turn on the second switch 22, and after the second switch 22 is turned on, to turn off the first switch 21, and after the first switch 21 is turned off, to turn off the second switch 22, so that the hybrid switch 2 is turned off.

[0142] In one possible implementation, the detection module 801 is also used to determine whether the battery cluster 1 is experiencing a state imbalance based on the state of the battery cluster 1 detected by the battery management unit.

[0143] In one possible implementation, the control module 802 is also used to send a charging command to the power converter 3 so that the power converter 3 converts the AC power from the AC power source into DC power to charge the battery cluster 1 connected to the power converter 3; or, to send a discharging command to the power converter 3 so that the power converter 3 converts the DC power output from the battery cluster 1 connected to it into AC power and outputs it to the AC power source.

[0144] The control device for the energy storage system provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0145] This application also provides an energy storage device, including an energy storage system and a control device.

[0146] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. An energy storage system, characterized by, include: Multiple battery clusters, multiple hybrid switches, and power converters; The battery clusters correspond one-to-one with the hybrid switches; the battery clusters are connected to one end of the power converter through the corresponding hybrid switches, and the other end of the power converter is connected to an AC power source. The hybrid switch is configured to turn on when the corresponding battery cluster is not in a state imbalance, so as to connect the battery cluster to the power converter; and to turn off when the corresponding battery cluster is in a state imbalance, so as to disconnect the connection between the battery cluster and the power converter.

2. The energy storage system of claim 1, wherein, The hybrid switch includes: a first switch and a second switch; The first switch and the second switch are connected in parallel.

3. The energy storage system of claim 2, wherein, The hybrid switch is activated when the corresponding battery cluster is not in a state imbalance, specifically including: The second switch is turned on when the corresponding battery cluster is not in an unbalanced state, and the first switch is turned on after the second switch is turned on, and the second switch is turned off after the first switch is turned on, so that the hybrid switch is turned on.

4. The energy storage system of claim 2, wherein, The hybrid switch disconnects when the corresponding battery clusters are in an unbalanced state, specifically including: When the corresponding battery cluster experiences an imbalance in its state, the second switch is activated, and after the second switch is activated, the first switch is deactivated, and after the first switch is deactivated, the second switch is deactivated, thereby deactivating the hybrid switch.

5. The energy storage system of claim 2, wherein, The first switch includes a mechanical switch, and the second switch includes a semiconductor switch.

6. The energy storage system of claim 1, wherein, The battery cluster includes: multiple battery packs; The multiple battery packs are connected in series.

7. The energy storage system of claim 6, wherein, The battery pack includes multiple battery cells; The multiple battery cells are connected in series.

8. The energy storage system of claim 6, wherein, The battery packs are of the same specifications.

9. The energy storage system of claim 1, wherein, The power converter is configured to convert AC power from the AC power source into DC power when a charging command is received, so as to charge the battery cluster connected to the power converter; and to convert DC power from the battery cluster connected to the power converter into AC power when a discharging command is received, so as to output the DC power to the AC power source.

10. The energy storage system of any one of claims 1 to 9, wherein, The energy storage system also includes: multiple battery management units; The battery management unit corresponds one-to-one with the battery cluster; the battery management unit is used to detect the status of the corresponding battery cluster and report the status.

11. A control method of an energy storage system, applied to the energy storage system according to any one of claims 1 to 10, characterized in that, The method includes: Detect the status of multiple battery clusters; When the plurality of battery clusters are not in an unbalanced state, the hybrid switch corresponding to the plurality of battery clusters is turned on to charge or discharge the plurality of battery clusters; and when the state of any battery cluster is unbalanced, the hybrid switch corresponding to that battery cluster is turned off to stop charging or discharging that battery cluster.

12. The control method according to claim 11, characterized by, The process of activating the hybrid switch corresponding to the plurality of battery clusters specifically includes: The second switch is turned on, and after the second switch is turned on, the first switch is turned on, and after the first switch is turned on, the second switch is turned off, so that the hybrid switch is turned on.

13. The control method according to claim 12, characterized in that, Disconnecting the hybrid switch corresponding to the battery cluster specifically includes: The second switch is turned on, and after the second switch is turned on, the first switch is turned off, and after the first switch is turned off, the second switch is turned off, so that the hybrid switch is turned off.

14. The control method according to claim 11, characterized by, The method further includes: Based on the state of the battery cluster detected by the battery management unit, it is determined whether the battery cluster is experiencing state imbalance.

15. The control method according to any one of claims 12 to 14, characterized by, The method further includes: A charging command is sent to the power converter to convert the AC power from the AC power source into DC power to charge the battery cluster connected to the power converter; or, a discharging command is sent to the power converter to convert the DC power output from the battery cluster connected to it into AC power and output it to the AC power source.

16. A control device of an energy storage system, applied to the energy storage system according to any one of claims 1 to 10, characterized in that, The control device includes: The detection module is used to detect the status of multiple battery clusters; The control module is configured to, when the plurality of battery clusters are not in a state imbalance, turn on the hybrid switch corresponding to the plurality of battery clusters to charge or discharge the plurality of battery clusters; and, when the state of any battery cluster is imbalanced, turn off the hybrid switch corresponding to that battery cluster to stop charging or discharging that battery cluster.

17. An energy storage device, comprising: It includes the energy storage system as described in any one of claims 1 to 10, and the control device as described in claim 16.

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