A method for achieving active battery balancing within a battery cluster in an energy storage power station.

Abstract

This invention relates to a method for active battery balancing within a battery cluster in an energy storage power station. The steps include: the energy storage power station system first scans the lowest and highest SOC batteries in a single string of batteries within the same cluster. If the SOC difference exceeds a first threshold, balancing is performed from the high-SOC batteries to the low-SOC batteries, and a current balancing channel is formed on each side of the single string of batteries. Several high-SOC battery blocks are selected to calculate the average SOC, and several low-SOC battery blocks are also selected to calculate the average SOC. If the difference between the average SOCs of the two blocks exceeds a second threshold, balancing is performed from the high-SOC battery blocks to the low-SOC battery blocks. The method also includes balancing between high- and low-SOC modules and between high- and low-SOC module groups. This invention helps overcome the inconsistency in SOC between batteries within a cluster and between modules within a cluster that occurs during the use of an energy storage power station, ensuring the energy storage capacity, rated output power, and service life of the power station.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method for achieving active battery balancing within a battery cluster in an energy storage power station. Background Technology

[0002] In the field of energy storage power station technology, the definition of a battery cluster is different from that of a battery or battery pack. Battery cells can be connected in series, parallel or series-parallel to form a battery cluster. The energy storage part in the battery is called the cell. The battery cluster is a battery assembly that can operate independently after being connected with the energy storage converter and auxiliary facilities.

[0003] Generally, energy storage battery systems consist of multiple battery clusters connected in parallel. After operating for a period of time, not only will there be significant differences in the State of Charge (SOC) between battery clusters, but also inconsistencies in SOC among the cells within each cluster. These SOC differences will affect the charging and discharging capacity of the energy storage battery system at its rated power, resulting in a decrease in the rated output power of the system. Clearly, problems originating locally can affect the entire energy storage power station. In other words, during operation, the consistency of SOC among the cells within each battery cluster will impact the energy storage capacity and the lifespan of the power station. Therefore, when the above situation is widespread, adjustments need to be made to the cells within the battery clusters or the modules composed of these cells.

[0004] While technicians can refer to previous techniques used to adjust the SOC between batteries or modules within a battery cluster, the details of these methods differ significantly, making them less valuable for reference. Furthermore, using adjustment devices to adjust the SOC of batteries within a battery cluster requires additional equipment connections and incurs substantial system losses during operation. Redesigning the charging scheme, on the other hand, is time-consuming and labor-intensive, and cannot be completed quickly.

[0005] In summary, this invention, based on existing known technologies and combined with practical application experience, comprehensively considers the problem of SOC consistency of batteries within a battery cluster exposed during the use of existing energy storage power stations, and provides a method for active battery balancing within a battery cluster in an energy storage power station. Through continuous practice and analysis following the proposal of this technical solution, it has been proven that the proposed technical solution effectively solves the problems existing in the prior art and also meets the current application needs of energy storage power stations. Summary of the Invention

[0006] To address the above deficiencies, this invention provides a method for active battery balancing within a battery cluster in an energy storage power station. This method can overcome the inconsistency in State of Charge (SOC) between batteries within a cluster and the large differences in SOC levels that occur during the use of an energy storage power station. It also helps to solve the problem of inconsistent SOC between modules within a cluster, thereby ensuring the energy storage capacity, rated output power, and service life of the energy storage power station.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for active battery balancing within a battery cluster in an energy storage power station, used to ensure real-time balancing among batteries within the cluster, includes the following steps:

[0009] Step 1: The energy storage power station equipment system first scans the lowest and highest SOC cells in a single string of batteries within the same cluster. If the SOC difference exceeds a set first threshold (e.g., 10% depending on application requirements), the system balances the batteries from the high SOC to the low SOC, forming a current balancing channel within the single string of batteries. Depending on the battery connection method in the actual design, the position of the current balancing channel is not fixed; for example, it can be located on both sides or on the same side of the battery pack.

[0010] Step 2: If no battery with a SOC difference exceeding the first threshold (e.g., the system is set to 10% based on application requirements) is found, the system continues scanning. After numerical comparison and judgment, several high-segment batteries are selected to calculate the average SOC, and several low-segment batteries are selected to calculate the average SOC. If the average SOC difference between these two parts exceeds the set second threshold (e.g., the system is set to 5% based on application requirements), the battery pack is balanced from the high-segment battery pack to the low-segment battery pack, and a current balancing channel is formed within a single battery string.

[0011] Step 3: When the energy storage power station equipment system scans modules containing single-string battery packs, if the difference between a single lowest SOC module and a single highest SOC module exceeds the first threshold (e.g., the system is set to 10% according to application requirements), the high SOC module is balanced to the low SOC module.

[0012] Step 4: If no module is found with a SOC difference exceeding the first threshold (e.g., the system is set to 10% based on application requirements), the system continues to scan each module. After comparing the values, several high-SOC modules are selected to form a module group and the average SOC is calculated. Then, several low-SOC modules are selected to form a module group and the average SOC is calculated. If the average SOC difference between these two module groups exceeds the set second threshold (e.g., the system is set to 5% based on application requirements), the module group will be balanced from the high-SOC module group to the low-SOC module group.

[0013] Technical personnel may further select the following technical means to supplement the above technical solutions:

[0014] In step one, a single battery pack uses several batteries connected in sequence, and each battery has a switch connected to both ends of the circuit, so that each battery's output circuit contains two switches.

[0015] If a single string of batteries in a battery cluster includes cells 1#, 2#, 3#, 4#, 5#, and 6#, and their SOCs are 90%, 85%, 85%, 80%, 70%, and 85% respectively, then during balancing, balancing will begin from cell 1# and proceed to cell 5#. At this time, switches S1, S5, S8, and S12 will be closed.

[0016] In step two, if a single battery pack includes cells 1#, 2#, 3#, 4#, 5#, and 6#, with their respective SOCs of 90%, 85%, 85%, 80%, 70%, and 70%, then during balancing, cells 1#, 2#, and 3# are considered to form a real-time high SOC battery pack, while cells 5# and 6# form another real-time low SOC battery pack. Between these two battery packs, cells 1#, 2#, and 3# simultaneously balance the SOCs of cells 5# and 6#. At this time, switches S1, S5, S10, and S13 are closed.

[0017] Within a battery pack with the same SOC, the individual cells have similar states of charge, thus allowing for balanced charging from the high-SOC battery pack to the low-SOC battery pack.

[0018] In addition, real-time balancing can be performed between modules with the largest SOC difference; each module contains at least one battery pack.

[0019] The technical solution of this invention is beneficial to overcoming the problems of inconsistent SOC between batteries within a cluster and large differences in SOC between batteries during the use of energy storage power stations. It also helps to solve the problem of inconsistent SOC between modules within a cluster, thereby ensuring the energy storage capacity, rated output power and service life of the energy storage power station. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings.

[0021] Figure 1 This invention describes a method for active battery balancing within a battery cluster in an energy storage power station, and its working principle is illustrated in the diagram. Figure 1 ;

[0022] Figure 2 This invention describes a method for active battery balancing within a battery cluster in an energy storage power station, and its working principle is illustrated in the diagram. Figure 2 . Detailed Implementation

[0023] The method for active battery balancing within a battery cluster in an energy storage power station, as implemented in this invention, aims to solve the problem of poor SOC consistency of batteries within the battery cluster affecting the stable operation of the power station system during previous use.

[0024] like Figure 1-2 As shown, the method for active battery balancing within a battery cluster in an energy storage power station implemented in this invention uses battery cells connected in series, parallel, or series-parallel to form battery clusters. Therefore, for ease of understanding, the balancing direction can be described using the directional positions of several batteries within each battery cluster, and the corresponding battery balancing strategy algorithm within the cluster is implemented as follows:

[0025] When technicians configure the corresponding algorithm, when the energy storage power station equipment system scans the lowest and highest SOC cells in a single battery string, if the SOC difference exceeds a first threshold set by the system (e.g., a threshold of 10%), then the high SOC cells are used to balance the low SOC cells. In the specific implementation of the in-cluster battery balancing strategy, six cells are connected sequentially, forming a current balancing channel on both sides or the same side of the battery pack. Each cell has switches connected to both ends of its circuit, resulting in each cell's output circuit containing two switches. For this six-cell in-cluster setup, a method is adopted where a single high SOC cell charges a single low SOC cell. If... Figure 1 For example, if there are cells 1#, 2#, 3#, 4#, 5# and 6# in sequence, with their SOCs being 90%, 85%, 85%, 80%, 70% and 85% respectively, then in the first balancing step, the balancing will start from cell 1# and proceed to cell 5#. At this time, switches S1, S5, S8 and S12 will be closed.

[0026] When implementing the intra-cluster battery balancing strategy, if the energy storage power station equipment system scans the lowest and highest SOC batteries in a single battery string and finds no batteries with an SOC difference exceeding a first threshold (e.g., 10%), the system continues scanning multiple batteries in the single battery string. After numerical comparison, the system selects several high-SOC blocks to calculate the average SOC, and then selects several low-SOC blocks to calculate the average SOC. If the average SOC difference between these two parts exceeds a second threshold set by the system (e.g., 5%), the battery balancing proceeds from the high-SOC battery string to the low-SOC battery string to accelerate battery balancing and shorten charging time. Figure 2For example, if cells 1#, 2#, 3#, 4#, 5#, and 6# are set sequentially with SOCs of 90%, 85%, 85%, 80%, 70%, and 70% respectively, then during balancing, the system considers cells 1#, 2#, and 3# as forming one real-time battery pack, and cells 5# and 6# as forming another real-time battery pack. Balancing occurs between these two battery packs, with cells 1#, 2#, and 3# simultaneously balancing towards cells 5# and 6#. At this time, switches S1, S5, S10, and S13 are closed. Therefore, when technicians configure the corresponding algorithm, if the SOC difference between the average SOC value of the selected high-SOC batteries and the average SOC value of the simultaneously selected low-SOC batteries exceeds a second threshold, then balancing will proceed from the high-SOC battery pack to the low-SOC battery pack.

[0027] The above-described method for active battery balancing within a battery cluster in an energy storage power station is implemented in accordance with the present invention. Since the batteries within a cluster are not necessarily composed of several batteries connected in series to form a battery pack, when there are multiple battery combinations within a battery cluster, each battery combination is regarded as a single module. When the energy storage power station equipment system scans out a single module with the lowest SOC and a single module with the highest SOC, if the SOC difference exceeds the first threshold set by the system (such as 10%), the high SOC module is balanced to the low SOC module. Of course, the determination of the SOC of the batteries within each module is calculated by the system according to the actual battery connection method, for example, by calculating the average value.

[0028] Building upon the previous step, when the energy storage power station equipment system scans the modules inside the battery cluster, if no module with a SOC difference exceeding the first threshold (e.g., 10%) is found, the system continues to scan each module. After comparing the values, the system selects several modules with relatively high SOC to form a module group and calculates the average SOC. Then, it selects several modules with relatively low SOC to form a module group and calculates the average SOC. If the average SOC difference between these two module groups exceeds the second threshold, the system will balance from the high SOC module group to the low SOC module group, which will help to further shorten the charging time.

[0029] Through the above implementation of the active battery balancing method within a battery cluster in an energy storage power station, it can be seen that the balancing method adopted includes not only the balancing methods between batteries within the cluster, but also the balancing methods between multiple modules within the cluster.

[0030] First, when there are several battery modules within a cluster, the highest SOC module charges and balances the power supply to the lowest SOC module. This achieves replenishment between the highest and lowest SOC modules, preventing the coexistence of modules with very low SOC and very high SOC within the same battery cluster, which would lead to ineffective balancing. Therefore, this method can achieve real-time balancing between modules with large SOC differences. Second, if after scanning, no single highest SOC module or single lowest SOC module is found to exceed the set threshold in real time, but rather modules with different SOCs are found, the system determines that a group of relatively high SOC modules form a high SOC module set, and a group of relatively low SOC modules form a low SOC module set. Modules within the same set have similar SOCs, and thus, the high SOC module set charges and balances the power supply to the low SOC module set. Obviously, through the implemented steps, this active balancing method can solve the imbalance problem of batteries or modules within a cluster. This addresses the imbalance between the remaining power in different parts of the cluster, promoting the maximum storage capacity of the energy storage power station and ensuring the rated output power.

[0031] The technical solution implemented in this invention mainly proposes a method for achieving active battery balancing within a battery cluster in an energy storage power station. This differs from inter-cluster balancing and should not be confused with solutions for inter-cluster (i.e., between battery clusters) balancing. Due to varying design and application requirements, no mandatory requirements are made regarding the specific type of battery cluster used in practice, the specific selection of battery components, or the connection method of batteries within the module. These are not significantly related to the technical solution implemented in this invention, and those skilled in the art can refer to existing conventional techniques for selection. Furthermore, this invention does not involve further improvements to circuit components or circuit diagrams, etc., in terms of specific circuit layout. Those skilled in the art will understand that implementing the steps of this invention can provide some inspiration for these technologies requiring further development. Therefore, the technical solution implemented in this invention is essentially a method for achieving active battery balancing within a battery cluster in an energy storage power station that can be implemented by those skilled in the art in conjunction with conventional techniques. Those skilled in the art can obtain a series of advantages by practicing and testing the method formed in this application according to different application conditions and requirements.

[0032] In the description of this specification, the terms "connection", "set", "have", etc. are interpreted in a broad sense. For example, "connection" can be a fixed connection or an indirect connection through an intermediate component without affecting the relationship between components and the technical effect. It can also be an integral connection or a partial connection. In such cases, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] The above description of the embodiments is intended to enable those skilled in the art to understand and apply them. It is obvious to those skilled in the art that they can easily make various modifications to these examples and apply the general principles described herein to other embodiments without creative effort. Therefore, this case is not limited to the above embodiments. Modifications in the following situations should also be within the scope of protection of this case: ① New technical solutions implemented based on the technical solutions of this invention and combined with existing common knowledge, where the technical effects of the new technical solutions do not exceed the technical effects of this invention, such as balancing high-SOC batteries to low-SOC batteries within the same battery cluster or balancing high-SOC battery combinations to relatively low-SOC battery combinations within the same battery cluster, and the resulting technical effects do not exceed the scope of this invention; ② Equivalent substitution of some features of the technical solutions of this invention using known technologies, resulting in the same technical effects as the technical effects of this invention, such as equivalent substitution of the batteries involved in the steps of this method and the modules composed of batteries; ③ Extensions based on the technical solutions of this invention, where the substantive content of the extended technical solutions does not exceed the scope of the technical solutions of this invention; ④ Solutions that apply the obtained technical means to other related technical fields by using equivalent transformations made by the textual description or the accompanying drawings of this invention.

Claims

1. A method for achieving active battery balancing within a battery cluster in an energy storage power station, used to ensure real-time balancing among batteries within the cluster, characterized in that, Includes the following steps: Step 1: The energy storage power station equipment system first scans the lowest and highest SOC cells in a single string of batteries within the same cluster. If the SOC difference exceeds the set first threshold, the high SOC cells are balanced to the low SOC cells, and a current balancing channel is formed within the single string of batteries. Step 2: If no battery with a SOC difference exceeding the first threshold is found, the system continues scanning. After numerical comparison and judgment, several high-segment batteries are selected to calculate the average SOC, and several low-segment batteries are selected to calculate the average SOC. If the average SOC difference between these two parts exceeds the set second threshold, the high-segment battery pack is balanced to the low-segment battery pack, and a current balancing channel is formed within a single battery pack. Step 3: When the energy storage power station equipment system scans modules containing single-string battery packs, if the difference between a single lowest SOC module and a single highest SOC module exceeds the first threshold, then the high SOC module is balanced to the low SOC module. Step 4: If no module with a SOC difference exceeding the first threshold is found, the system device continues to scan each module. After making a judgment by comparing the values, several high SOC modules are selected to form a module group and the average SOC is calculated. Then, several low SOC modules are selected to form a module group and the average SOC is calculated. If the average SOC difference between these two module groups exceeds the set second threshold, the balance is shifted from the high SOC module group to the low SOC module group. In step one, a single battery pack uses several batteries connected in sequence, and each battery has a switch connected to both ends of the circuit, so that each battery's output circuit contains two switches. Each module contains at least one battery pack.

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