A control method and system for a multi-cluster parallel battery

Abstract

The application discloses a control method of a multi-cluster parallel battery, which is applied to a power management system comprising a plurality of parallel battery clusters; the control method comprises the following steps: in step S1, a control unit acquires real-time state of charge and accumulative charge and discharge amount of all battery clusters, and executes a charge and discharge instruction by selecting a battery cluster with the minimum accumulative charge and discharge amount; in step S2, the control unit switches a battery cluster with extreme amount to another battery cluster for work according to the real-time state of charge; and the control unit switches a battery cluster with a work amount difference value in a preset amount interval to another battery cluster for work based on the accumulative charge and discharge amount. The application switches the working battery cluster by the real-time state of charge and the accumulative charge and discharge amount, avoids premature aging of some battery clusters due to long-term overload, ensures that all battery clusters cooperatively and uniformly reach the end of life, and improves the utilization rate of the battery cluster.

Description

Technical Field

[0001] This invention relates to the field of power storage control, and more particularly to a control method and system for multiple parallel-connected batteries. Background Technology

[0002] With the continuous expansion of new energy power generation and the increasing demand for peak shaving in power systems, electrochemical energy storage, as an important resource for flexible regulation, has been widely used in power systems. To meet the application requirements of large-capacity energy storage scenarios, multi-cluster parallel architecture has become the mainstream configuration for energy storage systems. This architecture connects multiple independent battery clusters in parallel to the DC bus, with a centralized power conversion unit handling energy conversion and management. This architecture has significant advantages in reducing system costs and simplifying operation and maintenance management. Current operation control of multi-cluster parallel energy storage systems mainly revolves around the real-time state of charge (SOC) balancing of battery clusters. By adjusting the charging and discharging power of each battery cluster, the SOC of different battery clusters is kept at a similar level, thereby avoiding overcharging or over-discharging of individual battery clusters. At the system scheduling level, the battery clusters to be put into operation are usually determined by polling or random selection, or dynamically selected based on parameters such as the real-time voltage and SOC of the battery clusters.

[0003] Existing operation and control strategies for multi-cluster parallel battery systems primarily focus on balancing the real-time operating status of battery clusters, failing to comprehensively consider the cumulative workload differences among clusters throughout the battery's entire lifecycle. Scheduling decisions based solely on real-time state of charge (SOC) result in some clusters undertaking more charging and discharging tasks for extended periods, while others experience relatively low utilization. Under this scheduling approach, the aging rates of different clusters differ significantly, limiting the overall lifespan of the energy storage system to the cluster that reaches its end-of-life earliest, leading to wasted battery assets. When a cluster reaches its SOC limit, existing control mechanisms lack smooth and reliable automatic switching strategies, easily resulting in DC bus voltage fluctuations or even system outages. Current control methods cannot achieve balanced control of the aging rates of each cluster, making it difficult to maximize the overall lifecycle value of the energy storage system. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a control method for multiple parallel battery clusters, applicable to an energy storage system, wherein the energy storage system includes multiple parallel battery clusters; The control method includes: Step S1: The control unit obtains the real-time state of charge and cumulative charge / discharge amount of all battery clusters in the energy storage system, and selects the battery cluster with the smallest cumulative charge / discharge amount to execute the charge / discharge command issued by the energy storage system. Step S2: The control unit determines whether the battery cluster executing the charge / discharge command is at its maximum charge level based on the real-time state of charge, and switches the battery cluster to execute the charge / discharge command when the battery cluster is at its maximum charge level; and The control unit obtains the workload difference value between the battery cluster currently executing the charge / discharge command and the other battery clusters based on the cumulative charge / discharge amount and processing, and switches the battery cluster to execute the charge / discharge command when the workload difference value is within a preset power range.

[0005] Preferably, when performing step S2, the control unit compares the real-time state of charge of the battery cluster executing the charge / discharge command with a preset limit threshold in each preset measurement cycle, and when the comparison result indicates that the battery cluster is at its limit capacity, the control unit switches the battery cluster executing the charge / discharge command to the battery cluster with the second smallest cumulative charge / discharge amount to execute the charge / discharge command.

[0006] Preferably, the limit threshold includes a maximum threshold and a minimum threshold; The maximum charge capacity includes the full charge capacity and the discharged capacity. Step S2 includes the control unit comparing the real-time state of charge of the battery cluster with the maximum threshold and the minimum threshold respectively: When the real-time state of charge is not less than the maximum threshold, the battery cluster is at the full charge level. The control unit disconnects the battery cluster currently executing the charge / discharge command and selects the battery cluster with the second smallest cumulative charge / discharge value to execute the charge / discharge command. When the real-time state of charge is not greater than the minimum threshold, the battery cluster is in the state of depletion. The control unit disconnects the battery cluster that is executing the charge / discharge command and selects the battery cluster with the second smallest cumulative charge / discharge amount to execute the charge / discharge command.

[0007] Preferably, the charge / discharge command includes a charging command and a discharging command; The battery cluster at the full charge level can only be selected to execute the discharge command; and The battery cluster that is in the state of being discharged can only be selected to execute the charging command.

[0008] Preferably, when performing step S2, the control unit processes and obtains the difference between the largest and smallest cumulative charge / discharge sums among all the battery clusters in each preset measurement cycle as the workload difference value, and when the charge / discharge difference value is greater than a preset first threshold and less than a preset second threshold, the battery cluster currently executing the charge / discharge command is switched to the battery cluster with the second smallest cumulative charge / discharge sum to execute the charge / discharge command. The power range is constituted by the first threshold and the second threshold; The first threshold is less than the second threshold.

[0009] Preferably, when a new battery cluster is connected in parallel to the energy storage system, the control unit switches the battery cluster that is currently executing the charging and discharging command to the new battery cluster to execute the charging and discharging command; When the difference between the largest cumulative charge / discharge sum among all battery clusters and the cumulative charge / discharge sum of a new battery cluster is not less than a preset third threshold, the control unit switches the battery cluster currently executing the charge / discharge command to the battery cluster with the second smallest cumulative charge / discharge sum to execute the charge / discharge command. When the cumulative charge / discharge amount and the charge / discharge amount after the second smallest battery cluster switch reach a preset fourth threshold, the control unit switches the battery cluster currently executing the charge / discharge command to a new battery cluster to execute the charge / discharge command.

[0010] Preferably, before the battery cluster selected for target switching is put into execution of the charge / discharge command, the control unit determines whether the candidate battery cluster is at the limit of power, and if the candidate battery cluster is at the limit of power, the candidate battery cluster is not selected, and the control unit proceeds to determine the next battery cluster with the next largest cumulative charge / discharge amount and the second smallest amount.

[0011] Preferably, when performing step S1, if the cumulative charge / discharge amounts of all the battery clusters are equal, the control unit selects the battery cluster with the highest real-time state of charge to execute the charge / discharge command.

[0012] Preferably, each of the battery clusters includes a diode contactor and a main contactor; When performing step S2, the control unit switches the battery cluster using the following steps: Step S21, the control unit closes the diode contactor of the battery cluster that is in operation; Step S22, the control unit disconnects the main contactor of the battery cluster that is in operation; Step S23, the control unit closes the main contactor of the battery cluster for target switching; In step S24, the control unit disconnects the diode contactor of the battery cluster that is in operation.

[0013] This invention discloses a control system for multi-cluster parallel batteries, which is applied to the control method described above; The energy storage system includes multiple battery clusters connected in parallel; The control system includes a control unit, the control unit comprising: The selection module is used to obtain the real-time state of charge and the cumulative charge and discharge amount of all battery clusters in the energy storage system, and select the battery cluster with the smallest cumulative charge and discharge amount to execute the charge and discharge command issued by the energy storage system. The first switching module, connected to the selection module, is used to determine whether the battery cluster executing the charging and discharging command is at its limit capacity based on the real-time state of charge, and to switch the battery cluster to execute the charging and discharging command when the battery cluster is at its limit capacity. The second switching module, connected to the selection module, is used to obtain the workload difference value between the battery cluster currently executing the charge / discharge command and the other battery clusters based on the cumulative charge / discharge amount and the processed value, and to switch the battery cluster to execute the charge / discharge command when the workload difference value is within a preset power range.

[0014] The following beneficial effects can be obtained by using the present invention: By controlling the switching of working battery clusters in real time based on the state of charge and cumulative charge / discharge, premature aging of some battery clusters due to long-term overload is prevented, ensuring that all battery clusters reach the end of their lifespan in a coordinated and uniform manner, thereby improving the utilization rate of battery clusters. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of the control method of the present invention; Figure 2 This is a schematic diagram of the process for switching battery clusters in this invention; Figure 3 This is a circuit topology diagram of each battery cluster in this invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0019] This invention discloses a control method for multiple parallel battery clusters, which is applied to an energy storage system, including multiple parallel battery clusters. like Figure 1 As shown, the control methods include: Step S1: The control unit obtains the real-time state of charge and cumulative charge / discharge amount of all battery clusters in the energy storage system, and selects the battery cluster with the smallest cumulative charge / discharge amount to execute the charge / discharge command issued by the energy storage system. Step S2: The control unit determines whether the battery cluster currently executing the charge / discharge command is at its maximum charge level based on the real-time state of charge, and switches the battery cluster to execute the charge / discharge command if the battery cluster is at its maximum charge level; and The control unit obtains the workload difference value between the battery cluster currently executing the charge / discharge command and the other battery clusters based on the cumulative charge / discharge amount and processing. When the workload difference value is within the preset power range, the control unit switches the battery cluster to execute the charge / discharge command.

[0020] Specifically, energy storage systems include EMS (Energy Management System), BCU (Battery Control Unit), and PCS (Power Conversion System).

[0021] Each battery cluster consists of several battery modules connected in series or in parallel. The clusters are independent of each other, and only one battery cluster can work at a time, i.e., execute charging and discharging commands.

[0022] The BCU monitors the voltage, temperature, and SOC (State of Charge) of each battery cluster in real time, as well as the cumulative charge and discharge amounts since the cluster was put into use. The cumulative charge and discharge amounts are summed to obtain the cumulative charge / discharge sum reflecting the historical workload of the battery cluster, and this sum is reported to the control unit via CAN (Controller Area Network) communication. The control unit continuously acquires the cumulative charge / discharge sum for each battery cluster.

[0023] Furthermore, the EMS acts as the dispatching center, simultaneously issuing power dispatching commands to the PCS and operation commands to the control unit. Upon receiving the operation command, the control unit, based on the SOC and cumulative charge / discharge amounts reported by each BCU, selects the battery cluster with the smallest cumulative charge / discharge amount for operation and issues a contactor control command to the corresponding BCU. After the BCU executes the contactor control command to connect the main circuit of the battery cluster, the PCS dispatches the charge / discharge commands according to the rated power, charging and discharging the selected battery cluster via the DC bus.

[0024] In a preferred embodiment of the present invention, when performing step S2, the control unit compares the real-time state of charge of the battery cluster executing the charge / discharge command with a preset limit threshold in each preset measurement cycle, and when the comparison result indicates that the battery cluster is at its limit capacity, the control unit switches the battery cluster executing the charge / discharge command to the battery cluster with the second smallest cumulative charge / discharge amount to execute the charge / discharge command.

[0025] Specifically, when the current battery cluster's SOC reaches the full charge threshold during charging or the empty discharge threshold during discharging, the control unit disconnects the current battery cluster and selects the battery cluster with the current cumulative charge / discharge amount and the second smallest amount for charging and discharging.

[0026] In one embodiment, the fill threshold is 95%.

[0027] In one embodiment, the venting threshold is 5%.

[0028] The fill threshold and empty threshold can be configured according to the actual situation.

[0029] In a preferred embodiment of the present invention, the limit threshold includes a maximum threshold and a minimum threshold; Maximum battery capacity includes both full charge capacity and fully discharged capacity; Step S2 includes the control unit comparing the real-time state of charge of the battery cluster with the maximum threshold and the minimum threshold, respectively: When the real-time state of charge is not less than the maximum threshold, the battery cluster is at full charge. The control unit disconnects the battery cluster currently executing the charge / discharge command and selects the battery cluster with the second smallest cumulative charge / discharge capacity to execute the charge / discharge command; and When the real-time state of charge is not greater than the minimum threshold, the battery cluster is in a state of depletion. The control unit disconnects the battery cluster that is executing the charge / discharge command and selects the battery cluster with the second smallest cumulative charge / discharge amount to execute the charge / discharge command.

[0030] In a preferred embodiment of the present invention, the charge / discharge command includes a charging command and a discharging command; Battery clusters at full charge can only be selected to execute discharge commands; and Battery clusters that are in a state of complete discharge can only be selected to execute charging commands.

[0031] Specifically, the disconnected battery clusters enter standby mode.

[0032] On the one hand, when the energy storage system issues a discharge command, the battery clusters that are fully charged temporarily enter the selection pool of available battery clusters. They can be compared with the cumulative charge and discharge of the normally operating battery clusters. After being selected, they leave the fully charged state and return to the available battery clusters when they are not completely discharged.

[0033] On the other hand, when the energy storage system issues a charging command, the battery clusters that are in a state of depletion temporarily enter the selection pool of available battery clusters. They can be compared with the cumulative charge and discharge of normally operating battery clusters. After being selected, they leave the depletion pool and return to the available battery clusters when they are not in a state of full charge.

[0034] In a preferred embodiment of the present invention, when performing step S2, the control unit processes and obtains the difference between the largest and smallest cumulative charge and discharge amounts among all battery clusters in each preset measurement cycle as the workload difference value, and when the difference between the charge and discharge amounts is greater than a preset first threshold and less than a preset second threshold, the battery cluster currently executing the charge and discharge command is switched to the battery cluster with the second smallest cumulative charge and discharge amount to execute the charge and discharge command. The first threshold and the second threshold constitute the energy range; The first threshold is less than the second threshold.

[0035] Specifically, the first threshold is when the current battery cluster has worked for N1 cycles of power, and the second threshold is when the current battery cluster has worked for N2 cycles of power.

[0036] Specifically, a cycle capacity is the cumulative charge and discharge amount of the current battery cluster and the amount of the battery cluster reaching its rated capacity.

[0037] In one embodiment, N1 is set to 2 and N2 is set to 3.

[0038] An embodiment is provided here to help those skilled in the art understand the working principle of switching battery clusters: After the system is powered on, the control unit reads the SOC value and cumulative charge / discharge amount and data uploaded by each BCU, and processes them to obtain: Cluster 1 (SOC=50%, TotalEng1=1000kWh), Cluster 2 (SOC=60%, TotalEng2=950kWh), Cluster 3 (SOC=55%, TotalEng3=1050kWh), Cluster 4 (SOC=65%, TotalEng4=900kWh).

[0039] When the system receives the first charge and discharge command, it will prioritize selecting the cluster with the smallest cumulative charge and discharge amount, namely cluster 4 (SOC=65%, TotalEng4=900kWh). If cluster 4 fails, the next smallest cluster 2 (SOC=60%, TotalEng2=950kWh) will be selected.

[0040] If no faulty cluster occurs, and cluster 4 triggers an extreme state, such as triggering a discharge switch when continuously discharging to 5%, or triggering a full charge switch when continuously charging to 95% SOC, the control unit selects the cluster with the smallest cumulative charge and discharge amount from the remaining fault-free clusters, i.e., cluster 2, to continue charging and discharging.

[0041] If the system remains in a smooth charge / discharge regulation state for an extended period, cluster 4 may operate for a long time, but its State of Charge (SOC) will fluctuate between 5% and 95%, never reaching its maximum capacity. During this period, the control unit continuously calculates the cumulative charge / discharge amount of each cluster. Thresholds N1 = 2 cycles of charge / discharge (assuming a single cluster's full charge / discharge capacity is 200 kWh, then N1 corresponds to 400 kWh), and N2 = 3. When the cumulative charge / discharge amount of cluster 4 reaches 1350 kWh, the difference between the cumulative charge / discharge amounts of cluster 4 and cluster 2 reaches threshold N1 and is less than threshold N2, satisfying the condition for triggering the workload difference. The control unit then automatically switches from cluster 4 to cluster 2 to continue charging and discharging.

[0042] In a preferred embodiment of the present invention, when a new battery cluster is connected in parallel to the energy storage system, the control unit switches the battery cluster that is currently executing the charge / discharge command to the new battery cluster to execute the charge / discharge command. When the difference between the sum of the largest cumulative charge and discharge values ​​among all battery clusters and the sum of the cumulative charge and discharge values ​​of a new battery cluster is not less than a preset third threshold, the control unit will switch the battery cluster currently executing the charge and discharge command to the battery cluster with the second smallest sum of cumulative charge and discharge values ​​to execute the charge and discharge command. When the cumulative charge / discharge amount and the cumulative charge / discharge of the second smallest battery cluster reach the preset fourth threshold, the control unit will switch the battery cluster that is currently executing the charge / discharge command to a new battery cluster to execute the charge / discharge command.

[0043] Specifically, the newly added battery cluster has a cumulative charge / discharge sum of 0, making it the battery cluster with the smallest cumulative charge / discharge sum in the energy storage system. Therefore, when a new battery cluster is added, it is preferred to operate from the new cluster. Simultaneously, to protect the newly added battery cluster, when the difference between the largest and smallest cumulative charge / discharge sum in the energy storage system is not less than N³ cycles, the currently operating battery cluster is switched to the second smallest cumulative charge / discharge sum. When the second smallest cumulative charge / discharge sum has operated for N⁴ cycles, the system switches back to the original battery cluster with the smallest cumulative charge / discharge sum for charging and discharging operations.

[0044] In one embodiment, N3 is set to 3.

[0045] In one embodiment, N4 is set to 1.

[0046] An embodiment is provided here to help those skilled in the art understand the switching method after a new battery cluster is connected: After the system powers on, the control unit reads the SOC value and cumulative charge / discharge amount and data uploaded by each BCU, and processes them to obtain: Cluster 1 (SOC=50%, TotalEng1=1000kWh), Cluster 2 (SOC=60%, TotalEng2=950kWh), Cluster 3 (SOC=55%, TotalEng3=1050kWh), and Cluster 4 (SOC=65%, TotalEng4=900kWh). After operating for a period of time, the system merges into a new cluster called Cluster 5 (SOC=30%, TotalEng5=0kWh). When the system receives the next charge / discharge command, it prioritizes selecting the cluster with the smallest cumulative charge / discharge amount, i.e., Cluster 5.

[0047] If no faulty cluster occurs, and cluster 5 is triggered in an extreme state (i.e., when continuously discharging to 5% triggers a discharge switch, or when continuously charging to 100% SOC triggers a full charge switch), the control unit selects the cluster with the smallest cumulative charge / discharge amount from the remaining fault-free clusters, i.e., cluster 4, for charging and discharging. When cluster 4 reaches its limit, the system will automatically switch to cluster 5, and so on. If cluster 5, after being incorporated into the system, operates in a smooth charge / discharge regulation state and does not trigger the extreme state condition, the control unit continuously calculates the cumulative charge / discharge amount of each cluster during this period. A threshold N3 is set for 3 cycles of charge / discharge (assuming a single cluster's full charge / discharge capacity is 200 kWh, then N3 corresponds to 600 kWh). When the cumulative charge / discharge amount of cluster 5 reaches 600 kWh, the triggering condition is met. The control unit automatically switches from cluster 5 to cluster 4 to continue charging / discharging. After cluster 4 completes N4 = 1 cycle, the system switches back to the cluster with the smallest current cumulative charge / discharge amount.

[0048] The specific values ​​of the first, second, third, and fourth thresholds can be optimized and adjusted based on factors such as battery chemical characteristics and system operation strategies.

[0049] In a preferred embodiment of the present invention, before the target battery cluster is put into execution of the charge and discharge command as a candidate battery cluster, the control unit compares the real-time state of charge of the candidate battery cluster with the limit threshold, and does not select the candidate battery cluster when the comparison result indicates that the candidate battery cluster is at the limit capacity, and then proceeds to judge the next cumulative charge and discharge amount and the second smallest battery cluster.

[0050] Specifically, the control unit determines whether to perform the aforementioned battery cluster switching operation in each preset control cycle. When switching battery clusters is required, the control unit compares the target battery cluster's SOC with the full charge and discharge capacity in the limit thresholds to determine whether the SOC of the selected target battery cluster is at the limit capacity, including not less than the full charge capacity and not more than the discharge capacity. If it is not at the limit capacity, the battery cluster can be selected; if it is at the limit capacity, the control unit switches to the next battery cluster with the smallest cumulative charge / discharge capacity and determines whether it can be selected.

[0051] In one embodiment, the control cycle is 20ms.

[0052] In a preferred embodiment of the present invention, when performing step S1, if the cumulative charge and discharge amounts of all battery clusters are equal, the control unit selects the battery cluster with the highest real-time state of charge to execute the charge and discharge command.

[0053] Specifically, before initially selecting the working battery cluster in step S1, the energy storage system performs fault detection on all battery clusters and disconnects any clusters in a faulty state. When a battery cluster is detected to have issues such as single-cell overvoltage, single-cell undervoltage, or single-cell overheating, that battery cluster is disconnected, and the fault information is reported to the staff. If all battery clusters are faulty, the control unit disconnects all battery clusters, preventing any cluster from being charged or discharged at high voltage until the staff repairs the fault and restarts the energy storage system.

[0054] Furthermore, when initially selecting a battery cluster for operation, the control unit chooses the cluster with the smallest cumulative charge / discharge amount among all battery clusters. If the cumulative charge / discharge amounts of all battery clusters are equal, the cluster with the highest State of Charge (SOC) is selected. If the cumulative charge / discharge amounts and SOC of all battery clusters are consistent, the control unit reads the addresses of all battery clusters and starts charging and discharging from the cluster with the smallest address, before proceeding with the subsequent battery cluster switching decision.

[0055] In a preferred embodiment of the present invention, each battery cluster includes a diode contactor and a main contactor; When performing step S2, such as Figure 2 As shown, the control unit switches the battery clusters using the following steps: Step S21: The control unit closes the diode contactor of the working battery cluster; Step S22: The control unit disconnects the main contactor of the working battery cluster; Step S23: The control unit closes the main contactor of the battery cluster for target switching; In step S24, the control unit disconnects the diode contactor of the working battery cluster.

[0056] Specifically, the diode contactor is an auxiliary switching device connected in series with the anti-reverse diode and in parallel on the branch of the main circuit of the positive terminal of the battery cluster. Under normal operation, it is in the open state, and the diode is not connected to the main circuit to avoid conduction losses. It is only briefly closed at the moment of battery cluster switching, so that the diode is temporarily connected to the circuit. The unidirectional conduction characteristic of the diode is used to carry the bus current, prevent the bus voltage from dropping during the switching process, realize seamless and smooth switching between battery clusters, and avoid the PCS from tripping due to voltage loss.

[0057] The main contactor, consisting of a positive main contactor and a negative main contactor, is a core power switching device connected in series in the positive and negative main circuits of the battery cluster, respectively. Under normal operation, it is in a closed state, carrying the entire charging and discharging current of the battery cluster and serving as the main path for power transmission between the battery cluster and the DC bus. When the battery cluster needs to be disconnected or switched, both the positive and negative main contactors simultaneously open, achieving complete electrical isolation between the battery cluster and the bus, ensuring system safety.

[0058] Furthermore, such as Figure 3 As shown, the State Grid 1, solar panels 2, and load 4 on the left achieve AC / DC energy conversion through integrated power equipment 3. The DC side of integrated power equipment 3 is connected in parallel to multiple battery clusters below through P+ / P- buses. Each battery cluster is equipped with an independent BMS (Battery Management System) for monitoring and protection. All BMSs achieve data interaction and collaborative control through a CAN bus composed of CAN_H and CAN_L. Each battery cluster's BMS is equipped with a human-machine interface 5 for operation monitoring and operation. The overall system realizes an energy storage system architecture of parallel operation of multiple battery clusters, unified power conversion, and distributed battery management.

[0059] When switching battery clusters, the control unit needs to control the diode contactors and main contactors of the currently operating battery cluster, as well as the diode contactors and main contactors of the target battery cluster. For example, when it detects that the currently operating battery cluster is completely discharged, the control unit sends an allowable discharge current of 0 to the EMS to ensure that the battery will no longer output current; then it closes the diode contactor of the currently operating cluster, and after closing the diode contactor, it opens the main positive and main negative contactors of the current cluster; next, it sends control commands to the battery cluster with the smallest cumulative charge / discharge amount and the second smallest amount, causing its main positive and main negative contactors to close respectively; after the main positive and main negative contactors are closed, it opens the diode contactor of the previously operating battery cluster; finally, the EMS discharges according to the allowable discharge current sent by the control unit. Throughout the entire process, the PCS only needs to operate according to the charge / discharge power sent by the EMS; if the sent charge / discharge power is 0, it is equivalent to disconnecting.

[0060] This invention discloses a control system for multi-cluster parallel batteries, which is applied to the control method for the aforementioned multi-cluster parallel batteries; The energy storage system includes multiple battery clusters connected in parallel; The control system includes a control unit, which includes: The selection module is used to obtain the real-time state of charge and cumulative charge / discharge amount of all battery clusters in the energy storage system, and select the battery cluster with the smallest cumulative charge / discharge amount to execute the charge / discharge command issued by the energy storage system. The first switching module, connected to the selection module, is used to determine whether the battery cluster executing the charging and discharging command is at its limit capacity based on the real-time state of charge, and to switch the battery cluster to execute the charging and discharging command when the battery cluster is at its limit capacity. The second switching module, connected to the selection module, is used to switch the battery cluster executing the charging and discharging command based on the cumulative charge and discharge amount and the difference in workload between the battery cluster currently executing the charging and discharging command and the other battery clusters, when the difference in workload is within a preset power range.

[0061] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for multi-cluster parallel batteries, applied to an energy storage system, characterized in that, The energy storage system includes multiple battery clusters connected in parallel; The control method includes: Step S1: The control unit obtains the real-time state of charge and cumulative charge / discharge amount of all battery clusters in the energy storage system, and selects the battery cluster with the smallest cumulative charge / discharge amount to execute the charge / discharge command issued by the energy storage system. Step S2: The control unit determines whether the battery cluster executing the charge / discharge command is at its maximum charge level based on the real-time state of charge, and switches the battery cluster to execute the charge / discharge command when the battery cluster is at its maximum charge level; and The control unit obtains the workload difference value between the battery cluster currently executing the charge / discharge command and the other battery clusters based on the cumulative charge / discharge amount and processing, and switches the battery cluster to execute the charge / discharge command when the workload difference value is within a preset power range.

2. The control method according to claim 1, characterized in that, When performing step S2, the control unit compares the real-time state of charge of the battery cluster executing the charge / discharge command with a preset limit threshold in each preset measurement cycle, and when the comparison result indicates that the battery cluster is at its limit capacity, the control unit switches the battery cluster executing the charge / discharge command to the battery cluster with the second smallest cumulative charge / discharge amount to execute the charge / discharge command.

3. The control method according to claim 2, characterized in that, The limit thresholds include a maximum threshold and a minimum threshold; The maximum charge capacity includes the full charge capacity and the discharged capacity. Step S2 includes the control unit comparing the real-time state of charge of the battery cluster with the maximum threshold and the minimum threshold respectively: When the real-time state of charge is not less than the maximum threshold, the battery cluster is at the full charge level. The control unit disconnects the battery cluster that is executing the charge / discharge command and selects the battery cluster with the second smallest cumulative charge / discharge level to execute the charge / discharge command. as well as When the real-time state of charge is not greater than the minimum threshold, the battery cluster is in the state of depletion. The control unit disconnects the battery cluster that is executing the charge / discharge command and selects the battery cluster with the second smallest cumulative charge / discharge amount to execute the charge / discharge command.

4. The control method according to claim 3, characterized in that, The charge / discharge commands include charging commands and discharging commands. The battery cluster at the full charge level can only be selected to execute the discharge command; and The battery cluster that is in the state of being discharged can only be selected to execute the charging command.

5. The control method according to claim 1, characterized in that, When performing step S2, the control unit processes and obtains the difference between the largest and smallest cumulative charge and discharge amounts among all the battery clusters in each preset measurement cycle as the workload difference value. When the difference between the charge and discharge amounts is greater than a preset first threshold and less than a preset second threshold, the battery cluster currently executing the charge and discharge command is switched to the battery cluster with the second smallest cumulative charge and discharge amount to execute the charge and discharge command. The power range is constituted by the first threshold and the second threshold; The first threshold is less than the second threshold.

6. The control method according to claim 1, characterized in that, When a new battery cluster is connected in parallel to the energy storage system, the control unit will switch the battery cluster that is currently executing the charge / discharge command to the new battery cluster to execute the charge / discharge command. When the difference between the largest cumulative charge / discharge sum among all battery clusters and the cumulative charge / discharge sum of a new battery cluster is not less than a preset third threshold, the control unit switches the battery cluster currently executing the charge / discharge command to the battery cluster with the second smallest cumulative charge / discharge sum to execute the charge / discharge command. When the cumulative charge / discharge amount and the charge / discharge amount after the second smallest battery cluster switch reach a preset fourth threshold, the control unit switches the battery cluster currently executing the charge / discharge command to a new battery cluster to execute the charge / discharge command.

7. The control method according to claim 1, characterized in that, Before the battery cluster selected for target switching is put into execution of the charge / discharge command, the control unit determines whether the candidate battery cluster is at the limit of power. If the candidate battery cluster is at the limit of power, the control unit does not select the candidate battery cluster and proceeds to determine the next battery cluster with the next largest cumulative charge / discharge amount.

8. The control method according to claim 1, characterized in that, When performing step S1, if the cumulative charge and discharge amounts of all the battery clusters are equal, the control unit selects the battery cluster with the highest real-time state of charge to execute the charge and discharge command.

9. The control method according to claim 1, characterized in that, Each of the battery clusters includes a diode contactor and a main contactor; When performing step S2, the control unit switches the battery cluster using the following steps: Step S21, the control unit closes the diode contactor of the battery cluster that is in operation; Step S22, the control unit disconnects the main contactor of the battery cluster that is in operation; Step S23, the control unit closes the main contactor of the battery cluster for target switching; In step S24, the control unit disconnects the diode contactor of the battery cluster that is in operation.

10. A control system for multi-cluster parallel batteries, characterized in that, Applied to the control method as described in any one of claims 1-9; The energy storage system includes multiple battery clusters connected in parallel; The control system includes a control unit, the control unit comprising: The selection module is used to obtain the real-time state of charge and the cumulative charge and discharge amount of all battery clusters in the energy storage system, and select the battery cluster with the smallest cumulative charge and discharge amount to execute the charge and discharge command issued by the energy storage system. The first switching module, connected to the selection module, is used to determine whether the battery cluster executing the charging and discharging command is at its limit capacity based on the real-time state of charge, and to switch the battery cluster to execute the charging and discharging command when the battery cluster is at its limit capacity. The second switching module, connected to the selection module, is used to obtain the workload difference value between the battery cluster currently executing the charge / discharge command and the other battery clusters based on the cumulative charge / discharge amount and the processing, and to switch the battery cluster to execute the charge / discharge command when the workload difference value is within a preset power range.

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