Battery system and multi-cluster inter-cluster equalization operation method

Abstract

The application discloses a battery system and a multi-cluster inter-cluster equalization operation method, and belongs to the equalization technical field of energy storage battery systems. The method comprises the following steps: a battery stack management unit acquires the state of charge (SOC) state of each battery cluster of a plurality of battery cluster management units through communication as a target judgment condition of multi-cluster inter-cluster equalization to perform input judgment conditions of an equalization strategy; it is judged whether the SOC range of each battery cluster in the whole system reaches an inter-cluster equalization starting condition, if yes, one battery cluster operation is performed according to the current energy storage system state to balance the values of each battery cluster SOC, the one battery cluster operation being one of a request for charging and / or a request for discharging and / or power-off; and the process is continued until the SOC of the multi-cluster battery cluster reaches an equalization closing condition. The application reduces the inconsistency of the inter-cluster capacity of the battery cluster, thereby improving the consistency of different battery clusters of the whole energy storage battery system, and effectively prolonging the service life of the whole energy storage battery system.

Description

Technical Field

[0001] This invention belongs to the field of equalization technology of energy storage battery systems, and in particular to a battery system and a method for equalization operation among multiple clusters. Background Technology

[0002] With the rapid development of power energy storage systems, the energy and voltage levels required for energy storage battery systems are becoming increasingly higher, as are the required number of battery cells. An energy storage system often consists of multiple battery clusters connected in series and parallel within a single system unit. A single battery cluster, for different DC voltage levels, can consist of hundreds or even thousands of individual battery cells connected in series and parallel. Such a large number of battery cells in series and parallel exacerbates the bottleneck effect of the energy storage system. Therefore, ensuring the consistency of individual cells, modules, and clusters within the energy storage system places high demands on it. Improving the consistency of the entire energy storage battery system—including the consistency of battery clusters, battery modules, and individual cells—to extend the lifespan of energy storage systems and extend the life cycle of large-scale energy storage systems has become a problem to be solved. How to effectively ensure the consistency of each battery cluster in the energy storage system and avoid the "bottleneck" effect caused by inconsistencies in voltage differences and state of charge (SOC) between battery clusters, thus affecting the full and effective utilization of some energy in the entire system, requires a technical approach to ensuring the consistency between battery clusters.

[0003] Therefore, it is necessary to adopt a suitable inter-cluster balancing method for energy storage battery systems in this application scenario to balance the battery clusters of the entire system. It is of great importance to provide an inter-cluster balancing method that can effectively balance the various clusters of the entire system, ensure that each battery cluster does not affect the normal operation of the entire energy storage system, ensure the consistency between battery clusters of the entire energy storage battery system in real time, improve the consistency of the entire energy storage battery system, ensure the effective utilization of the energy of the entire system, and extend the life of the entire energy storage system. Summary of the Invention

[0004] The purpose of this invention is to provide a battery system and a method for balanced operation among multiple clusters to solve the problems involved in the background art.

[0005] Based on the above-mentioned technical problems, the present invention proposes a battery system and a method for balanced operation among multiple clusters, including the following two aspects.

[0006] In a first aspect, the present invention provides a battery system, the system comprising:

[0007] An energy storage system is composed of at least two battery clusters connected in parallel; each battery cluster is composed of at least two cell modules connected in series and parallel.

[0008] A battery management system includes at least one battery stack management unit, at least two battery cluster management units, and several battery module management units; the battery stack management unit coordinates and manages at least two battery cluster management units; each battery cluster management unit coordinates and manages at least one battery module management unit; the battery module management units manage the battery cell modules.

[0009] The high-voltage box corresponds one-to-one with the battery cluster management unit and performs actions to realize the functions of the battery cluster management unit controlling the DC high voltage of the battery cluster to power on and / or power off.

[0010] The energy storage inverter corresponds one-to-one with the battery stack control unit and performs charging and discharging actions based on the charging and discharging power fed back by the battery stack control unit.

[0011] Preferably or optionally, the communication between the battery cluster management unit and the battery stack management unit is achieved by establishing a matching and clustering communication protocol on the communication link to facilitate communication between each battery cluster.

[0012] The present invention also provides a method for equalizing operation among multiple clusters based on the battery system, the method comprising:

[0013] The battery stack management unit obtains the SOC status of each battery cluster from multiple battery cluster management units through communication, and uses it as the target judgment setting for the equalization strategy among multiple clusters.

[0014] Determine whether the SOC difference between each battery cluster in the entire system reaches the inter-cluster equalization activation condition. If so, perform a request to charge and / or request to discharge and / or power off one of the battery clusters according to the current energy storage system state to balance the SOC values ​​between each battery cluster.

[0015] This continues until the SOC state of the multiple battery clusters reaches the condition for balanced shutdown.

[0016] Preferably or optionally, the inter-cluster equalization activation condition is that the SOC difference between each battery cluster is >5%, and the inter-cluster equalization deactivation condition is that the SOC difference between each battery cluster is ≤5%.

[0017] Preferably or optionally, the method further includes:

[0018] When the battery stack management unit detects a protection alarm fault state in the entire energy storage system, the battery stack management unit terminates the operation of the multi-cluster equalization operation method and controls all battery clusters to perform a power-down operation.

[0019] Preferably or optionally, the method further includes:

[0020] To prevent the energy storage system from remaining in a balanced state for an extended period without exiting the balanced state, the system will start a countdown for the single-time balance timeout while in a balanced state. If the countdown is completed and the system still has not exited the balanced state, it will exit the single-time balance and wait for the single-time restart balance delay to be completed before re-judging the logic.

[0021] Preferably or optionally, the method further includes:

[0022] Once the equalization activation conditions are met, the battery stack management unit will perform different equalization response operations based on the current state of the energy storage system, whether it is in charging, discharging, or standby mode.

[0023] Preferably or optionally, the method further includes:

[0024] During the execution of the multi-cluster balancing strategy, when a single battery cluster is powered on or off, the energy storage battery stack management unit will send the synchronous system request charging and discharging power to the energy storage inverter to feed back and perform synchronous power following for balancing control.

[0025] During the charging and discharging process, i.e., in the charging state or the resting state, the battery stack control unit requests the charging and discharging power P. sys The battery cluster management unit requests the charging and discharging power P. cluster The number of battery clusters in the system is N. sys The number of battery clusters N powered on in the system online ,

[0026] Under normal conditions, the system's charge / discharge request power Psys = N online *Min(P cluster ), N sys ≥N online ;

[0027] After equalization is completed, the power-on request before power-off cluster charging and discharging request power Psys = Min(N) online *Min(P cluster ),10),N sys ≥N online ;

[0028] During the balancing process, the requested power for charging and discharging of the battery cluster is Psys = Min((N online -1)*Min(P cluster ),10),N sys ≥N online .

[0029] Preferably or optionally, the method further includes: the time interval between the above-described multi-cluster equalization operation strategy method executed by the battery stack management unit is at least 1 minute.

[0030] This invention relates to a battery system and a method for equalizing operation among multiple clusters. Compared with the prior art, this invention has the following advantages:

[0031] 1. This invention establishes an inter-cluster balancing strategy at the battery cluster level in the energy storage battery system. The balancing strategy is mainly coordinated by the upper-level battery stack management unit to perform an inter-cluster balancing mechanism synchronously with the battery cluster management unit. This balancing control strategy method can execute the parallel inter-cluster strategy of battery clusters without affecting the normal operation of the energy storage system, thereby quickly and stably achieving inter-cluster balancing, reducing the inconsistency of capacity between battery clusters, and thus improving the consistency between different battery clusters in the entire energy storage battery system, effectively extending the service life of the entire energy storage battery system.

[0032] 2. This invention, through this equalization control strategy, ensures that each battery cluster in the entire energy storage battery system can perform time-sharing equalization, thus guaranteeing the safety, stability, and reliability of the entire system. At the same time, the equalization control strategy ensures that only one battery cluster is performing charge-discharge equalization at any given time. Simultaneously, the battery stack control unit synchronously reduces its power to follow suit and perform charge-discharge equalization control, preventing the impact on the lifespan of the battery cluster relays caused by the opening and closing of the circuit breaker during the power-on and power-off processes under high current charging and discharging.

[0033] 3. The present invention has novel logic. The current conventional balancing mode is the battery module balancing mode. This invention mainly focuses on the balancing control strategy between battery clusters in the entire battery system, which is quite innovative. Attached Figure Description

[0034] Figure 1 This is a battery system architecture diagram according to an embodiment of the present invention;

[0035] Figure 2 This is a block diagram of the inter-cluster balanced operation system according to an embodiment of the present invention;

[0036] Figure 3 This is a block diagram of the high-voltage box system according to an embodiment of the present invention;

[0037] Figure 4 This is a flowchart illustrating the high-voltage closing and connection process of the battery cluster according to an embodiment of the present invention.

[0038] Figure 5 This is a flowchart illustrating the high-voltage tripping and exit process of the battery cluster according to an embodiment of the present invention.

[0039] Figure 6 This is a flowchart illustrating the timed inter-cluster load balancing operation in an embodiment of the present invention. Detailed Implementation

[0040] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0041] Example 1

[0042] See appendix Figure 1 This embodiment provides a battery system, including: an energy storage system, a battery management system, a high-voltage box, and an energy storage inverter.

[0043] The energy storage system consists of at least two battery clusters connected in parallel; each battery cluster consists of at least two cell modules connected in series and parallel; and each cell module is mainly composed of cells connected in series and parallel.

[0044] See appendix Figure 2 The Battery Management System (BMS) includes at least one Battery Array Unit (BAU), at least two Battery Cluster Units (BCUs), and several Battery Module Units (BMUs). The Battery Array Unit (BAU) is the system's main controller, coordinating and managing the at least two Battery Cluster Units (BCUs). Each Battery Cluster Unit (BCU) is a system battery cluster controller, coordinating and managing at least one Battery Module Unit. Each Battery Module Unit (BMU) is a system battery module controller, used to manage cell modules and collect cell voltage, temperature, and perform cell balancing control.

[0045] Each high-voltage box corresponds one-to-one with a Battery Cluster Management Unit (BCU). The BCU executes actions to control the DC high-voltage power-on and / or power-off of the battery clusters. The high-voltage box includes a main positive relay, a main negative relay, a pre-charge relay, a fuse, a circuit breaker, a current transformer, a pre-charge resistor, and a DC high-voltage circuit. For detailed circuit connections, please refer to the appendix. Figure 3The high-voltage box is equipped with a main positive relay and a main negative relay programmable switch execution unit, which has the function of controlling the DC high voltage power-on and power-off switching. The battery cluster management unit (BCU) has a control interface to control the main positive / main negative / precharge relay programmable switch execution unit. The programmable switches are executed in a certain sequence to realize the function of controlling the DC high voltage power-on and power-off switching of the battery cluster by the BCU. In the power-on closing operation, the battery cluster management unit (BCU) controls the main negative relay to close, and then controls the precharge relay to close. When the precharge voltage reaches 95% of the total voltage, the battery cluster management unit (BCU) controls the main positive relay to close and simultaneously opens the precharge relay. In the power-off opening operation, the battery cluster management unit (BCU) controls the main positive relay to open, and then controls the main negative relay to open.

[0046] The energy storage inverter PCS corresponds one-to-one with the battery stack control unit BAU, and performs charging and discharging actions based on the charging and discharging power fed back by the battery stack control unit.

[0047] In this system, the battery management system (BMS) uses a single communication link between the battery array unit (BAU) and the battery cluster management system unit (BCU), forming the system's communication architecture. This link allows each battery cluster to send status-related messages to the BAU. This communication method enables information sharing between the BCUs and the BAU, with the communication method not limited to RS485, CAN, CAN-FD, or Ethernet. Furthermore, the BAU can send messages to the BCU via a communication bus. The BCU then performs power-on / off actions on the battery clusters, disconnecting a specific battery cluster from the DC connection of the entire system. In this embodiment, communication between the BAU and BCU is conducted via a CAN communication link, and the communication protocol is not limited to standard or extended frame protocols. Communication between the energy storage inverter (PCS) and the BAU is also conducted via a CAN communication link, primarily exchanging battery status and charging / discharging power requests. The CAN communication protocol is not limited to standard or extended frame protocols.

[0048] Example 2

[0049] Based on the battery system described in Embodiment 1 above, this embodiment also provides a method for equalizing operation between multiple clusters. The method includes: the Battery Stack Management Unit (BAU) obtains the SOC state of each battery cluster from multiple Battery Cluster Management Units (BCUs) via communication as the target judgment setting for inter-cluster equalization, and uses this as the input judgment condition for the equalization strategy; it determines whether the SOC range between each battery cluster in the entire system reaches the inter-cluster equalization activation condition; if so, it performs a request to charge and / or request to discharge and / or power off one of the battery clusters according to the current energy storage system state to balance the SOC values ​​between the various battery clusters; until the state of charge of the multiple battery clusters reaches the equalization shutdown condition. By establishing an inter-cluster equalization strategy at the battery cluster level in the energy storage battery system, the equalization strategy is mainly coordinated by the upper-level Battery Stack Management Unit (BAU) to synchronously perform an inter-cluster equalization mechanism with the Battery Cluster Management Units (BCUs). This equalization control strategy method can execute the parallel inter-cluster strategy without affecting the normal operation of the energy storage system, thereby quickly and stably achieving inter-cluster equalization, reducing the inconsistency of capacity between battery clusters, and thus improving the consistency between different battery clusters in the entire energy storage battery system, effectively extending the service life of the entire energy storage battery system.

[0050] It should be noted that only one battery cluster can enter the equalization state at a time; multiple clusters cannot simultaneously enter the SOC equalization state. The equalization strategy can run in both the charging / discharging and idle states of the energy storage system. The equalization strategy includes strategies for when the energy storage system is not in an equalization state and strategies for when the energy storage system is in an equalization state.

[0051] In a further embodiment, the inter-cluster equalization activation condition is that the SOC difference between each battery cluster is >5%, and the inter-cluster equalization deactivation condition is that the SOC difference between each battery cluster is ≤5%. Of course, 5% is not a fixed value, and those skilled in the art can make adaptive adjustments based on factors such as the type of battery system and the usage environment.

[0052] In a further embodiment, when the battery stack management unit (BAU) detects a protection alarm fault state in the entire energy storage system, the battery stack management unit (BAU) terminates the operation of the multi-cluster equalization operation method and controls all battery clusters to perform a power-down operation.

[0053] In a further embodiment, the method further includes: to prevent the energy storage system from remaining in a balanced state for an extended period without exiting the balanced state, the system will count down the single-cycle balanced timeout while in the balanced state. If the countdown completes and the system still has not exited the balanced state, it will exit the single-cycle balanced state and wait for the single-cycle restart balanced delay to complete before re-judging the logic. Specifically, the single-cycle balanced timeout between multiple clusters is 5 minutes, and the single-cycle restart balanced timeout is 2 minutes. Preferably, the restart balanced timeout is only required when a balanced timeout occurs.

[0054] In a further embodiment, the method further includes: when the equalization activation condition is met, the battery stack management unit (BAU) will perform different equalization response operations based on the current state of the energy storage system, whether it is in a charging state, a discharging state, or a standby state. Specifically, when the energy storage system is in a charging state, it performs the operation of the cluster with the highest SOC; when the energy storage system is in a discharging state, it performs the operation of the cluster with the lowest SOC; when the energy storage system is in a standby state, the system requests charging or discharging based on whether the average SOC of the clusters exceeds 50%. If the average SOC of the clusters is greater than 50%, it requests discharging; if the average SOC of the clusters is less than or equal to 50%, it requests charging.

[0055] In a further embodiment, the method further includes: during the power-on or power-off process of a single battery cluster during the execution of the multi-cluster balancing strategy, the energy storage battery stack management unit (BAU) sends a synchronous system request for charging and discharging power to the energy storage inverter to provide feedback for synchronous power following and balancing control; during the charging and discharging process, i.e., in the charging state or the resting state, the battery stack control unit requests the charging and discharging power P. sys The battery cluster management unit (BCU) requests charging and discharging power P. cluster The number of battery clusters in the system is N. sys The number of battery clusters N powered on in the system online ,

[0056] Under normal conditions, the system's charge / discharge request power Psys = N online *Min(P cluster ), N sys ≥N online ;

[0057] After equalization is completed, the power-on request before power-off cluster charging and discharging request power Psys = Min(N) online *Min(P cluster ),10),N sys ≥N online ;

[0058] During the balancing process, the requested power for charging and discharging of the battery cluster is Psys = Min((N online -1)*Min(P cluster ),10),N sys ≥N online .

[0059] Specifically, the inter-cluster balancing logic strategy includes a timed inter-cluster balancing operation process for the energy storage battery system, a high-voltage closing and activation process for battery clusters, a high-voltage opening and deactivation process for battery clusters, and a power request strategy for charging and discharging. These logic strategy processes constitute a method for inter-cluster balancing of the entire system. When the overall battery management system (BMS) is powered on, the battery stack management unit (BAU) obtains information such as SOC, charging and discharging request power, and battery cluster status reported by the lower battery cluster management units (BCUs). Here, it is assumed that the SOC of cluster 1 is 15%, the SOC of cluster 2 is 18%, and the SOC of cluster 3 is 21%, and the system has no alarms or faults, is not in a balancing state, and is in a charging state. The overall system inter-cluster balancing operation strategy method includes the following steps:

[0060] Furthermore, the timed inter-cluster balancing operation logic flow strategy of the energy storage battery system is the overall flow strategy of the entire inter-cluster balancing method of the energy storage battery system, such as... Figure 6 As shown, it includes the following steps:

[0061] S301: The battery stack management system (BAU) determines whether the battery cluster is in an alarm or fault state based on the battery status reported by the current system cluster 1, cluster 2, and cluster 3. If it is in an alarm or fault state, it jumps to step S302. If the overall system is not in an alarm or fault state, it jumps to step S303. In this embodiment, it jumps to S303.

[0062] S302: The battery stack management system (BAU) is in an alarm or protection state. The logic does not enter the inter-cluster balance judgment and directly exits the overall balance logic.

[0063] S303: The battery stack management system is not in an alarm or fault state. The battery stack management system BAU determines whether the current state of the three battery clusters has been triggered to enter the balancing state. If the current system is in the balancing state, it jumps to step S3011. If the current system is not in the balancing state, it jumps to step S304. In this embodiment, if it is not in the balancing state, it jumps to S304.

[0064] S304: The battery stack system BAU determines whether the system currently meets the conditions for entering the equalization start-up based on the SOC values ​​of each cluster fed back by each cluster. The equalization start-up condition is that the SOC range is >5%. If the equalization start-up is not met, it means that the energy storage system has good consistency and does not need to be equalized to exit the overall system logic. In this embodiment, if the SOC difference between cluster 3 and cluster 1 meets the equalization start-up condition, then proceed to step S305.

[0065] S305: The battery stack management system (BAU) judges the status of the entire system. If the energy storage system is in a charging state, it jumps to step S309. If the energy storage system is in a discharging state, it jumps to step S310. If the energy storage system is in a standby state, it jumps to step S306. In this embodiment, if it is in a discharging state, it jumps to step S310.

[0066] S306: The energy storage system is in a standby state. The battery stack control unit (BAU) determines that the average SOC of the entire system cluster is ≥50%. If the average SOC of the cluster is ≥50% in the current standby state, proceed to step S308. If the average SOC of the cluster is <50% in the current standby state, proceed to step S307.

[0067] S307: The Battery Stack Management Unit (BAU) requests charging from the Energy Storage Inverter (PCS).

[0068] S308: The battery stack management system (BAU) requests discharge from the energy storage inverter (PCS).

[0069] S309: If the battery stack management system (BAU) is currently in a charging state, it will send a control command to the battery cluster management unit (BCU) to power down the highest SOC cluster.

[0070] S310: If the battery stack management system (BAU) is currently in a discharge state, it sends a control command to the battery cluster management unit (BCU) to power down the lowest SOC cluster; in this embodiment, the lowest SOC cluster is powered down as battery cluster 1.

[0071] S311: The system performs a countdown to determine the equalization timeout; if the equalization timeout occurs, proceed to step S313; if the equalization timeout does not occur, proceed to step S312.

[0072] S312: If the system is balancing and the balancing timeout has not expired, determine whether the system has reached the balancing shutdown condition; if the battery cluster SOC range is <5%, if the balancing shutdown condition is met, proceed to step S313; if not, proceed to S301 to re-determine.

[0073] S313: If the system is balancing and the balancing timeout has expired, the previously powered-down clusters will be restored to the powered-on state and the overall balancing logic will be exited.

[0074] When the information from the three battery clusters is aggregated and coordinated by the Battery Stack Management Unit (BAU) of the Battery Management System (BMS) to trigger the equalization process according to the above logic, after Cluster 1 is powered down, the parallel battery systems of Clusters 2 and 3 continue to discharge until the difference in State of Charge (SOC) of the battery clusters is ≤5%, reaching the equalization shutdown adjustment stage. This continuous discharge then triggers the equalization shutdown operation process, as follows: Figure 4 The high-voltage closing and connection process of the energy storage battery system shown above restores the power to the previously de-energized battery cluster 1.

[0075] like Figure 4 The system's high-voltage closing and connection process strategy for the battery clusters is shown. The system operation method includes the following steps:

[0076] S101: The Battery Stack Management Unit (BAU) determines whether there is a fault in the three battery clusters in the energy storage battery system; if there is a fault, it exits the high-voltage closing process, otherwise it jumps to step S102; in this embodiment, if there is no fault, it jumps to step S102.

[0077] S102: The battery stack management unit (BAU) determines whether there is a de-energized battery cluster among the three battery clusters in the energy storage battery system; if there is no de-energized battery cluster in the system, the high-voltage closing process is exited; otherwise, the process jumps to step S103.

[0078] S103: The battery stack management unit (BAU) determines whether the SOC of the lower battery cluster meets the equalization shutdown power-on condition; the equalization shutdown condition between multiple clusters is that the SOC of each battery cluster is ≤5%. If the equalization shutdown condition is not met, it means that the equalization exit high voltage closing process has not been completed. Otherwise, jump to step S104.

[0079] S104: The Battery Stack Management Unit (BAU) sends the synchronous system's requested charge / discharge power to the inverter PCS system for feedback, enabling synchronous power following and charge / discharge balancing control. Before the balancing request is powered on, the requested charge / discharge power Psys = Min(N online* Min(P cluster ),10);

[0080] S105: The Battery Stack Management Unit (BAU) sends a command to the Battery Cluster Management Unit (BCU) to perform a power-on operation.

[0081] like Figure 5 The system's high-voltage tripping and exit procedure for the battery cluster, as shown, includes the following steps:

[0082] S201: The Battery Stack Management Unit (BAU) determines whether there is a fault in each battery cluster in the energy storage battery system; if there is a fault, it exits the high voltage tripping process; otherwise, it jumps to step S202.

[0083] S202: The battery stack management unit (BAU) determines whether the equalization start condition is triggered based on the equalization strategy. The equalization start condition between multiple clusters is that the SOC of each battery cluster is greater than 5%. If the equalization start condition is not met, the high voltage tripping process is exited; otherwise, the process jumps to step S203.

[0084] S203: The Battery Stack Management Unit (BAU) sends the synchronous system's requested charge / discharge power to the inverter PCS system for feedback, enabling synchronous power following and charge / discharge balancing control. When the balancing request is discontinued, the requested charge / discharge power Psys = Min((N online -1) * Min(P cluster ),10);

[0085] S204: The Battery Stack Management Unit (BAU) sends a command to the Battery Cluster Management Unit (BCU) to perform a power-down operation.

[0086] In summary, the entire system operates according to the above process, employing a cluster balancing logic strategy for a three-cell parallel energy storage battery system. During charging and discharging, the state of each cell cluster changes, triggering different balancing strategy branches to achieve overall inter-cluster balance. This balancing strategy is primarily coordinated by the upper-level battery stack management unit (BAU) and the battery cluster management unit (BCU) to synchronously perform an inter-cluster balancing mechanism. This balancing control strategy can execute the parallel cell cluster strategy without affecting the normal operation of the energy storage system, thus achieving rapid and stable inter-cluster balancing. Through this logical process, the SOC difference among the three cell clusters can be cyclically kept within 5%, reducing capacity inconsistency between cell clusters and improving the consistency of different cell clusters in the entire energy storage battery system, effectively extending the lifespan of the entire energy storage battery system. This balancing method ensures time-sharing balancing of each battery cluster in the entire energy storage battery system, guaranteeing the safety, stability, and reliability of the entire system. Furthermore, the balancing control strategy ensures that only one battery cluster is undergoing charge / discharge balancing at any given time. Simultaneously, the battery stack control unit (BAU) synchronously reduces its power to follow the requested charge / discharge power and interacts with the energy storage inverter (PCS) to perform charge / discharge balancing control. This prevents the impact on the lifespan of the battery cluster relays caused by excessive current during charging and discharging operations. Currently, the conventional balancing mode is a passive balancing mode at the cell level of the battery module. This invention primarily focuses on a novel balancing control strategy at the inter-cluster level for each battery cluster within the entire battery system.

[0087] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for equalizing operation among multiple clusters in a battery system, characterized in that, This operating method is based on a battery system, which includes: An energy storage system is composed of at least two battery clusters connected in parallel; each battery cluster is composed of at least two cell modules connected in series and parallel. A battery management system includes at least one battery stack management unit, at least two battery cluster management units, and several battery module management units; the battery stack management unit coordinates and manages at least two battery cluster management units; each battery cluster management unit coordinates and manages at least one battery module management unit; the battery module management units manage the battery cell modules. The high-voltage box corresponds one-to-one with the battery cluster management unit and performs actions to realize the functions of the battery cluster management unit controlling the DC high voltage of the battery cluster to power on and / or power off. The energy storage inverter corresponds one-to-one with the battery stack management unit and performs charging and discharging actions based on the charging and discharging power fed back by the battery stack management unit. The method includes the following steps: S301: The battery stack management unit determines whether the battery cluster is in an alarm or fault state based on the battery status reported by each battery cluster in the current system; if it is in an alarm or fault state, it jumps to step S302; if the overall system is not in an alarm or fault state, it jumps to step S303. S302: When the battery stack management unit is in alarm or protection mode, the logic will exit the overall balance logic directly without entering the inter-cluster balance judgment. S303: The battery stack management unit is not in an alarm or fault state. The battery stack management unit determines whether each battery cluster has triggered and entered the balancing state. If the current system is in the balancing state, it jumps to step S3011. If the current system is not in the balancing state, it jumps to step S304. S304: The battery stack management unit determines whether the system currently meets the conditions for entering the equalization start condition based on the SOC value of each cluster fed back by each cluster; the equalization start condition is that the SOC range is >5%; if it is not met, the overall system logic is exited. S305: The battery stack management unit judges the status of the entire system. If the energy storage system is in the charging state, it jumps to step S309. If the energy storage system is in the discharging state, it jumps to step S310. If the energy storage system is in the standby state, it jumps to step S306. S306: The energy storage system is in a standby state. The battery stack management unit determines that the average SOC of the entire system cluster is ≥50%. If the average SOC of the cluster is ≥50% in the current standby state, proceed to step S308. If the average SOC of the cluster is <50% in the current standby state, proceed to step S307. S307: The battery stack management unit requests charging from the energy storage inverter; wherein, the charging and discharging power requested by the battery stack management unit is Psys, the charging and discharging power requested by the battery cluster management unit is Pcluster, the number of battery clusters in the system is Nsys, and the number of battery clusters powered on in the system is Nonline; under normal conditions, the system charging and discharging requested power Psys = Nonline·Min(Pcluster), Nsys ≥ Nonline. S308: The battery stack management unit requests discharge from the energy storage inverter; under normal conditions, the system's charge and discharge request power Psys = Nonline·Min(Pcluster), Nsys ≥ Nonline; S309: If the battery stack management unit is currently in a charging state, it will send a control command to the battery cluster management unit to power down the highest SOC cluster. S310: If the battery stack management unit is currently in a discharge state, it will send a control command to the battery cluster management unit to power down the lowest SOC cluster. S311: The system performs a countdown to determine the equalization timeout; if the equalization timeout occurs, proceed to step S313; if the equalization timeout does not occur, proceed to step S312. S312: If the system is balancing and the balancing timeout has not expired, determine whether the system has reached the balancing shutdown condition; if the battery cluster SOC range is <5%, if the balancing shutdown condition is met, proceed to step S313; if not, proceed to S301 to re-determine. S313: If the system is balancing and the balancing timeout has expired, the previously powered-down clusters will be restored to the powered-on state before exiting the overall balancing logic.

2. The multi-cluster balanced operation method according to claim 1, characterized in that, The communication between the battery cluster management unit and the battery stack management unit is achieved by establishing a matching and clustering communication protocol on the communication link to facilitate communication between each battery cluster.

3. The method for balanced operation among multiple clusters according to claim 1, characterized in that, The method further includes: During the execution of the multi-cluster balancing strategy, when powering on a single battery cluster, the energy storage battery stack management unit sends the synchronous system request charging and discharging power to the energy storage inverter to provide feedback and perform synchronous power following for balancing control. Before the balancing request is powered on, the charging and discharging request power = Min(Nonline·Min(Pcluster),10), Nsys≥Nonline.

4. The method for balanced operation among multiple clusters according to claim 1, characterized in that, The method further includes: During the execution of the multi-cluster equalization strategy, when a single battery cluster is powered on, the energy storage battery stack management unit sends the synchronous system request charging and discharging power to the energy storage inverter to perform synchronous power following for equalization control. Before the equalization request is powered off, the charging and discharging request power Psys = Min((Nonline-1)·Min(Pcluster),10), Nsys≥Nonline.

5. The method for balanced operation among multiple clusters according to claim 1, characterized in that, The method further includes: the time interval between the above-mentioned multi-cluster equalization operation method executed by the battery stack management unit is at least 1 minute.

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