Lithium battery cross-cabin electric quantity compensation equalization system and method

Abstract

The invention relates to a lithium battery cross-cabin electric quantity compensation equalization system, which comprises a compensation module, a battery cabin selection module and a battery unit selection module, each battery unit is correspondingly connected with a battery gating switch, the battery gating module in each battery cabin is connected to the corresponding battery cabin gating switch, and the battery cabin gating switches are connected to a compensation module, so that the corresponding battery cabin gating switch and the corresponding battery gating switch are determined to be closed according to a target battery unit needing to be compensated; and connecting the target battery unit with the compensation module, and balancing and compensating the target battery unit by controlling the power of the compensation module. Compared with the prior art, the consistency of the whole energy storage battery station can be kept, the problem that the minimum battery cluster of the whole energy storage battery station is limited can be solved, the power and electric quantity release aspects of the whole energy storage battery station can be optimized, and the overall performance and the available capacity of the large lithium battery energy storage power station can be improved.

Description

Technical Field

[0001] This invention relates to the field of battery energy storage system technology, and in particular to a lithium battery cross-compartment power compensation and balancing system and method. Background Technology

[0002] With the large-scale integration of renewable energy and the increasing demand for power system regulation capabilities, energy storage systems are being used more and more widely in the power grid. This is especially true in large-scale lithium battery energy storage power stations, where the requirements for continuous charging and discharging power are extremely high, as are the requirements for the consistency of all battery clusters throughout the station. Because individual battery cells exhibit differences in parameters such as capacity and internal resistance during manufacturing, assembly, transportation, storage, and use, voltage imbalances occur between individual cells, making inconsistencies in battery packs and clusters even more pronounced.

[0003] In existing energy storage systems, individual battery cells are connected in series and parallel to form battery boxes, battery boxes are connected in series and parallel to form battery clusters, and multiple battery clusters are connected in parallel on the DC side to form an energy storage battery stack.

[0004] Existing balancing methods are all carried out within a single battery stack, such as the mainstream active balancing and passive balancing. These methods cannot improve the overall consistency of the energy storage power station. Therefore, when these methods are widely used in large-scale lithium battery energy storage power stations, they often fail to effectively solve the problem of the minimum battery cluster constraint of the entire station.

[0005] Adjustments at the energy storage power station level are often based on power regulation between battery stacks to ensure the consistency of the entire station's battery stacks, which cannot guarantee that the entire station will achieve optimal power and energy release. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a lithium battery cross-compartment power compensation and equalization system.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] This invention provides a lithium battery cross-compartment power compensation and equalization system, including a compensation module, a battery compartment selection module, and a battery cell selection module;

[0009] The energy storage battery station has multiple battery compartments, and the battery clusters in the battery compartments form multiple battery units. The battery compartment selection module has a battery compartment selection switch corresponding to the battery compartment, and the battery unit selection module has a battery selection switch corresponding to the battery unit. Each battery unit is connected to a corresponding battery selection switch, and the battery selection module in each battery compartment is connected to the corresponding battery compartment selection switch. The battery compartment selection switches are all connected to the compensation module. The target battery unit to be compensated is determined by closing the corresponding battery compartment selection switch and the corresponding battery selection switch, so that the target battery unit is connected to the compensation module. The power of the compensation module is controlled to balance and compensate the target battery unit.

[0010] Compared with existing technologies, this invention connects each battery cell to a corresponding battery selection switch, and each battery selection module in each battery compartment is connected to a corresponding battery compartment selection switch. These battery compartment selection switches are all connected to a compensation module. The invention can determine the closing of the corresponding battery compartment selection switch and the corresponding battery selection switch based on the target battery cell requiring compensation, thus connecting the target battery cell to the compensation module. By controlling the power of the compensation module, the target battery cell is balanced and compensated, thereby maintaining the consistency of the entire energy storage battery station. Furthermore, it can solve the problem of minimum battery cluster constraints in the entire energy storage battery station, optimize the power and energy release of the entire energy storage battery station, and improve the overall performance and available capacity of large-scale lithium battery energy storage power stations.

[0011] Preferably, the energy storage battery station is divided into multiple areas, each area has multiple battery compartments, and the compensation module includes multiple compensation power units corresponding to the areas. The battery compartment selection switch of each area is connected to the corresponding compensation power unit.

[0012] Compared with existing technologies, this invention optimizes the cost-effectiveness of power storage power stations by configuring compensation devices according to regions, thus reducing the number of compensation devices. Furthermore, by dividing the system topology of power compensators according to regions and selecting target battery compartments, it can select to compensate battery cells within the target battery compartment, achieving regional-level compensation effects and further ensuring that the power storage power station achieves optimal performance in terms of power and energy release.

[0013] Preferably, the power compensation unit is connected to the regional AC bus, the battery compartment selection switch is connected to the battery selection switch through the battery compartment DC compensation bus, and the number of regions is the same as the number of regional AC buses or is a multiple of the number of regional AC buses.

[0014] Compared with existing technologies, the power compensation unit is connected to the regional AC bus, which can convert AC to DC and supply it to the battery unit. The number of regions is the same as or a multiple of the number of regional AC buses, which can ensure the economy of the solution.

[0015] Preferably, the power compensation unit communicates with the energy storage battery station management system to adjust the power.

[0016] Preferably, the compensation power of the battery unit is determined by the power of the power compensation unit, and the maximum compensation power of the power compensation unit is determined according to 5% to 10% of the bus charging and discharging power.

[0017] Compared with existing technologies, the maximum compensation power of the power compensation unit is determined according to 5% to 10% of the bus charging and discharging power, which can prevent bus overload.

[0018] Preferably, the battery unit includes a battery pack and / or a battery half-cluster.

[0019] Preferably, the battery compartment contains multiple battery clusters, each containing the same number of battery cells arranged in series, so that both the battery cell selection module and the battery compartment selection module form an array;

[0020] The battery selection switch includes an input switch and an output switch; the battery compartment selection switch includes a positive switch and a negative switch.

[0021] Each battery cell has an input switch connected to its input terminal and an output switch connected to its output terminal. The input switch of each battery compartment is connected to the corresponding positive switch, and the output switch of each battery compartment is connected to the corresponding negative switch.

[0022] Preferably, the target battery cell is determined by its open-circuit voltage and state of charge, and a short-board battery cell is selected.

[0023] The present invention also provides a lithium battery cross-compartment power compensation and balancing method, which applies any of the lithium battery cross-compartment power compensation and balancing systems described above, including: determining the target battery cell to be compensated by the open circuit voltage and state of charge; determining and closing the corresponding battery compartment selection switch and the corresponding battery selection switch according to the target battery cell to be compensated, so that the target battery cell is connected to the compensation module; and balancing and compensating the target battery cell by controlling the power of the compensation module.

[0024] Preferably, after compensating the target battery cell, the target battery cell that needs to be compensated is repositioned by the open circuit voltage and SOC, the switching selection action is repeated, and the compensation and equalization of the newly determined target battery cell continues. Attached Figure Description

[0025] Figure 1 This is a system block diagram of the present invention;

[0026] Figure 2 This is a schematic diagram of the single-unit compensation system according to Embodiment 1 of the present invention;

[0027] Figure 3 This is a detailed structural diagram of the battery compartment in the system of Embodiment 1 of the present invention;

[0028] Figure 4 This is a schematic diagram of the semi-cluster compensation system according to Embodiment 2 of the present invention;

[0029] Figure 5 This is a detailed structural diagram of the battery compartment in the system of Embodiment 2 of the present invention. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0031] Chinese invention patent document CN110504725A discloses a method and device for rapid equalization control of multiple battery stacks in an energy storage power station. The control method divides the state of charge (SBC) of the battery stacks into several regions, updating the SBC and depth of discharge differently in each region. Based on the updated SBC and depth of discharge, active power commands are sequentially and proportionally assigned to each battery stack. Simultaneously, by setting thresholds for SBC and depth of discharge updates, frequent switching of energy storage power is avoided. This improves the equalization speed of the SBC of multiple battery stacks in the energy storage power station, improves the operating conditions of the energy storage power station, and increases its availability. At the same time, it minimizes energy storage power switching, improving the stability and grid friendliness of the energy storage power station.

[0032] However, the rapid equalization control method and device for multiple battery stacks in this energy storage power station adjusts the active power of each battery stack according to the state of charge (SOC) and depth of discharge in each area. Specifically, during charging, battery stacks with a high SOC have lower active power, while those with a low SOC have higher active power; during discharging, battery stacks with a high SOC have higher active power, and those with a low SOC have lower active power. To ensure stable overall power, this adjustment method essentially uses the overload capacity of the battery stacks to meet the active power regulation. Since the overload capacity of the battery stacks is limited, the adjustment depth of this method is very limited. This equalization method does not involve internal adjustment of the battery stacks, which can cause a few battery stacks to be in an overloaded state for extended periods, affecting the overall lifespan of the internal battery, electrical, and heat dissipation components.

[0033] Chinese invention patent document CN114726065A discloses a battery capacity balancing control method and system. The method includes: acquiring the state of each battery in each battery cluster of an energy storage system, and determining whether there are battery clusters with abnormal battery states in the energy storage system based on the state of each battery; if there are battery clusters with abnormal battery states in the energy storage system, then using a current-limiting distribution mode to balance the capacity of each battery cluster in the energy storage system; if there are no battery clusters with abnormal battery states in the energy storage system, then using a power-sharing mode or a state-of-charge balancing mode to balance the capacity of each battery cluster in the energy storage system.

[0034] However, the battery capacity balancing control method and system determine whether some battery clusters need to be limited in power by checking the capacity status and whether there are any abnormalities in each battery cluster. This balancing is carried out within the battery stack. Although it can adjust the state of the battery clusters within the battery stack to be consistent, the differences between battery stacks have a significant impact on the entire station because the power value of the entire energy storage station needs to be controlled as the target value in the use of large power stations.

[0035] Chinese invention patent document CN114865747A discloses an online balancing method for the state-of-charge (POC) power scheduling of energy storage battery clusters. The method determines the charge / discharge state of each battery cluster based on power scheduling commands. By using the POC, charge / discharge limit power, and power scheduling command value for each battery cluster, the online balancing time is estimated in real time. The charging or discharging power of each battery cluster is calculated in real time based on the online balancing time, and the power scheduling commands for each battery cluster are sent to their respective power converters. Each power converter then controls the charging or discharging of its own battery cluster. This invention considers the influence of the charge / discharge limit power of the battery cluster, i.e., the charge / discharge rate, enabling online balancing of the POC during power scheduling.

[0036] However, this online balancing method for power dispatching of energy storage battery clusters obtains the state of charge (SOC) of each battery cluster and adjusts the power of the power converter configured in each cluster to achieve the adjustment of the power and SOC of each cluster. This method, like the patent document with publication number CN110504725A, essentially uses the overload capacity of the battery stack to meet the regulation of active power. Due to the limited overload capacity of the battery stack, the adjustment depth of this method is very limited. Furthermore, configuring a large number of battery cluster power converters not only requires very high real-time control of the entire station, but also results in very high costs.

[0037] In addition, Chinese patent document CN118899963A discloses a multi-level energy storage system and its power balancing method; Chinese patent document CN116599181A also discloses an online balancing device and method for series battery clusters; Chinese patent document CN112510270A also discloses a unified control method and system for multi-level state of charge balancing of energy storage systems; and Chinese patent document CN118487354A also discloses a dynamic balancing unit, a dynamic balancing system and method for battery clusters, and an energy storage system.

[0038] In view of the above, the technical solutions provided by the various embodiments of this application will be described below with reference to the accompanying drawings.

[0039] This specification presents an embodiment of a lithium battery cross-cell power compensation and balancing system, such as... Figure 1 and Figure 2 As shown, the system includes a compensation module, a battery compartment selection module, and a battery cell selection module. The energy storage battery station has multiple battery compartments, and each battery compartment contains multiple battery cells. The battery compartment selection module has a corresponding battery compartment selection switch, and the battery cell selection module has a corresponding battery selection switch. Each battery cell is connected to a corresponding battery selection switch. Each battery compartment's battery selection module is connected to its corresponding battery compartment selection switch, and these switches are all connected to the compensation module. The system determines the closing of the corresponding battery compartment selection switch and the corresponding battery selection switch based on the target battery cell to be compensated, connecting the target battery cell to the compensation module. The compensation module's power is controlled to balance and compensate the target battery cell. Initially, both the battery compartment selection switch and the battery selection switch are in the open state.

[0040] In one embodiment, such as Figure 2 and Figure 3 As shown, the energy storage battery station is divided into multiple zones, each with multiple battery compartments. To ensure the economic efficiency of the solution, the number of zones can be equal to the number of cascaded buses in the energy storage station, or a multiple thereof. The compensation module includes multiple compensation power units corresponding to the zones, and the selection switch for each zone's battery compartment is connected to the corresponding compensation power unit. The compensation power unit is also called a zone compensation module or power compensator. There is a one-to-one correspondence between zones and compensation power units; n zones result in n compensation power units. Each zone can have n battery compartments, and each battery compartment can contain n battery clusters.

[0041] In one embodiment, such as Figure 1 and Figure 2As shown, the power compensation unit is connected to the regional AC bus, and the battery compartment selection switch is connected to the battery selection switch through the battery compartment DC compensation bus. The number of regions is the same as the number of regional AC buses or is a multiple of the number of regional AC buses. In the regional AC buses, A, B, and C represent three-phase lines, and N represents the neutral line.

[0042] In one embodiment, the power compensation unit comprises a DC side module, a power conversion module, a control system module, an AC side module, and other communication auxiliary modules. Its main principle is the same as that of the main circuit energy storage converter. In use, the power compensation unit can communicate with the battery management system or the whole station management system to perform power regulation.

[0043] In one embodiment, the compensation power of the battery cell is determined by the power of the power compensation unit. Since the overload capacity of the design bus is usually 10%, the maximum compensation power of the compensation unit is determined according to 5%-10% of the charging and discharging power of the main bus.

[0044] In one embodiment, the battery unit includes a battery pack and / or a battery half-cluster, and the battery pack or battery half-cluster can be selected as the final compensation object according to actual design needs.

[0045] In one embodiment, the battery compartment contains multiple battery clusters, each with the same number of battery cells connected in series, so that both the battery cell selection module and the battery compartment selection module form an array, forming a target compartment selection array and a target battery pack or battery cluster selection array.

[0046] The battery selection switch includes an input switch and an output switch; the battery compartment selection switch includes a positive switch and a negative switch; the input terminal of each battery cell is connected to the corresponding input switch, the output terminal of each battery cell is connected to the corresponding output switch, the input switch of each battery compartment is connected to the corresponding positive switch, and the output switch of each battery compartment is connected to the corresponding negative switch.

[0047] like Figure 1 As shown, the system consists of a regional compensation device, a target battery compartment selection array, and a battery pack or battery cluster selection array. The regional compensation device is a power compensation actuator, through which the compensation system is connected to the regional AC bus; the target battery compartment selection array is an external switch selection array, through which the system connects to the DC compensation bus of the battery compartment requiring compensation via a selector switch; the target battery pack or battery cluster selection array is an internal switch selection array, through which the system connects to the DC compensation bus of the battery compartment and then connects to the positive and negative terminals of the target battery cluster or battery pack requiring compensation via a selector switch.

[0048] In one embodiment, the target battery cell is determined by its open-circuit voltage and state of charge, and the short-board battery cell is selected.

[0049] like Figure 2 He Ru Figure 3 Example 1 shown: A compensation power unit is configured on the regional bus. For example, based on the current open-circuit voltage or SOC of the battery cell, the target compensation cell is determined to be the first cell of battery cluster 2 in battery compartment #2 within the region. Then, the positive and negative switches #2 in the target compartment selection array are closed, while other switches in the target compartment selection array remain open. Next, switches 2-1 and 2-2 in battery compartment #2 within the region are closed. At this point, the target cell is connected to the compensation power module. By controlling the power of the compensation power unit, the target cell can be balanced and compensated. As compensation occurs, the target cell may change. After repositioning the cell requiring compensation based on the open-circuit voltage and SOC (State of Charge), the switch selection action is repeated to continue compensating and balancing other cells.

[0050] like Figure 4 and Figure 5 Example 2 shown: A compensation power unit is configured on the regional bus. For example, based on the open-circuit voltage or SOC of the battery half-cluster, it is determined that the target compensation half-cluster is the upper half-cluster of battery cluster 2 in battery compartment #2 within the region. Then, the positive and negative switches #2 in the target compartment selection array are closed, while other switches in the target compartment selection array remain open. Next, switches 2-1 and 2-2 in battery compartment #2 within the region are closed. At this point, the target half-cluster is connected to the compensation power module. By controlling the power of the compensation power unit, the target half-cluster can be balanced and compensated. As compensation occurs, the target half-cluster may change. After repositioning the half-cluster requiring compensation based on the open-circuit voltage and SOC, the switch selection action is repeated to continue compensating and balancing other half-clusters.

[0051] The present invention can also install equalization circuits between battery packs within the cluster and configure cluster compensation devices on the battery cluster outlet side, but configuring these components at the same time will increase the cost.

[0052] This specification also provides a lithium battery cross-compartment power compensation and balancing method. The lithium battery cross-compartment power compensation and balancing system applied in any of the above embodiments includes: determining the target battery cell that needs to be compensated by the open circuit voltage and state of charge; determining and closing the corresponding battery compartment selection switch and the corresponding battery selection switch according to the target battery cell to be compensated, so that the target battery cell is connected to the compensation module; and balancing and compensating the target battery cell by controlling the power of the compensation module.

[0053] In one embodiment, after compensating the target battery cell, the target battery cell that needs to be compensated is repositioned by the open circuit voltage and SOC, the switching selection action is repeated, and the compensation and equalization of the newly determined target battery cell continues.

[0054] This invention is a novel lithium battery cross-compartment capacity compensation and balancing system. By configuring one or more battery pack-level / semi-cluster-level compensation devices in different areas of the entire energy storage battery station, it performs battery pack-level / semi-cluster-level capacity compensation and balancing across battery compartments, ensuring that the entire power station achieves optimal performance in terms of power and energy release, thereby improving the overall performance and available capacity of large-scale lithium battery energy storage power stations.

[0055] This invention features compensation devices configured according to regions (cascaded buses). These devices compensate for battery packs / half-clusters, and their compensation power depends on the power of the compensation device itself, not being constrained by the overload capacity of the original charging and discharging system. Since the energy compensation targets the battery packs / half-clusters in the target compartment, balancing and energy compensation can be performed on the shortest battery pack or cluster within the region, achieving stable discharge and power across the entire region. Because the compensation devices are configured according to regions, the regions can be configured according to cascaded buses, minimizing the number of compensation devices and maximizing cost-effectiveness.

[0056] This invention divides the system topology of power compensators by region and selects target battery compartments; it can select to compensate for battery packs / half-clusters in the target battery compartment, achieving regional compensation effect and ensuring that the energy storage power station achieves optimal performance in terms of power and energy release.

[0057] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A lithium battery cross-compartment power compensation and balancing system, characterized in that, Includes a compensation module, a battery compartment selection module, and a battery cell selection module; The energy storage battery station has multiple battery compartments, and the battery clusters in the battery compartments form multiple battery units. The battery compartment selection module has a battery compartment selection switch corresponding to the battery compartment, and the battery unit selection module has a battery selection switch corresponding to the battery unit. Each battery unit is connected to a corresponding battery selection switch, and the battery selection module in each battery compartment is connected to the corresponding battery compartment selection switch. The battery compartment selection switches are all connected to the compensation module. The target battery unit to be compensated is determined by closing the corresponding battery compartment selection switch and the corresponding battery selection switch, so that the target battery unit is connected to the compensation module. The power of the compensation module is controlled to balance and compensate the target battery unit.

2. The lithium battery cross-compartment power compensation and balancing system according to claim 1, characterized in that, The energy storage battery station is divided into multiple areas, each area has multiple battery compartments, and the compensation module includes multiple compensation power units corresponding to the areas. The battery compartment selection switch of each area is connected to the corresponding compensation power unit.

3. The lithium battery cross-compartment power compensation and balancing system according to claim 2, characterized in that, The power compensation unit is connected to the regional AC bus, and the battery compartment selection switch is connected to the battery selection switch through the battery compartment DC compensation bus. The number of regions is the same as the number of regional AC buses or is a multiple of the number of regional AC buses.

4. The lithium battery cross-compartment power compensation and balancing system according to claim 3, characterized in that, The power compensation unit communicates with the energy storage battery station management system to adjust the power.

5. The lithium battery cross-compartment power compensation and equalization system according to claim 4, characterized in that, The compensation power of the battery unit is determined by the power of the power compensation unit, and the maximum compensation power of the power compensation unit is determined according to 5% to 10% of the bus charging and discharging power.

6. The lithium battery cross-compartment power compensation and equalization system according to any one of claims 1 to 5, characterized in that, The battery unit includes a battery pack and / or a battery half-cluster.

7. The lithium battery cross-compartment power compensation and equalization system according to any one of claims 1 to 5, characterized in that, The battery compartment contains multiple battery clusters, each with the same number of battery cells connected in series, so that both the battery cell selection module and the battery compartment selection module form an array. The battery selection switch includes an input switch and an output switch; the battery compartment selection switch includes a positive switch and a negative switch. Each battery cell has an input switch connected to its input terminal and an output switch connected to its output terminal. The input switch of each battery compartment is connected to the corresponding positive switch, and the output switch of each battery compartment is connected to the corresponding negative switch.

8. The lithium battery cross-compartment power compensation and equalization system according to any one of claims 1 to 5, characterized in that, The target battery cell is determined by its open-circuit voltage and state of charge, and a short-board battery cell is selected.

9. A method for cross-compartment capacity compensation and balancing in lithium batteries, characterized in that, The lithium battery cross-compartment power compensation and equalization system according to any one of claims 1 to 8 includes: determining the target battery cell that needs to be compensated by the open circuit voltage and state of charge; determining the closing of the corresponding battery compartment selection switch and the corresponding battery selection switch for the target battery cell that needs to be compensated; connecting the target battery cell to the compensation module; and equalizing and compensating the target battery cell by controlling the power of the compensation module.

10. The lithium battery cross-compartment power compensation and equalization method according to claim 9, characterized in that, After compensating the target battery cell, the target battery cell that needs to be compensated is repositioned by the open circuit voltage and SOC. The switching selection action is repeated to continue to compensate and equalize the newly determined target battery cell.

Images