Series direction reconstruction method based on dynamic reconfigurable energy storage system

Abstract

The invention discloses a series direction reconstruction method based on a dynamic reconfigurable energy storage system, and relates to the field of energy storage of a new energy power system. In order to overcome the defects that when series batteries of an existing energy storage system are unbalanced, passive equalization is needed, additional balancing devices and equipment are needed, the equalization efficiency is low, and circuit switching loss is large, a battery system is constructed into a dynamic reconfigurable battery system; the m battery modules are arranged in a descending order according to the SOC initial values; the battery modules corresponding to the first m-1 SOC initial values are discharged; the m discharged battery modules are arranged in an ascending order according to the current SOC primary discharge value; the battery modules corresponding to the first m-1 SOC primary discharge values are charged; the charging and discharging processes are repeated, and in any charging or discharging process, if the SOC standard deviation is smaller than or equal to a standard deviation threshold value, charging and discharging are stopped. The method is mainly used for dynamically reconstructing the batteries in the series connection direction of the energy storage system.

Description

Technical Field

[0001] This invention relates to the field of energy storage in new energy power systems, and in particular to a method for series directional reconfiguration of a dynamically reconfigurable energy storage system. Background Technology

[0002] In the field of new energy batteries, electrochemical energy storage systems, primarily based on lithium-ion batteries, are widely used. When numerous battery modules are connected in series, inconsistencies gradually emerge over long-term use. For example, the differences in charge and voltage between battery modules gradually widen, seriously affecting the lifespan and safety of the battery system. Currently, the main method for handling inconsistencies between batteries is passive balancing. This method is slow, especially when the cell capacity is large, and its effectiveness is poor. In large-scale energy storage systems, the number of battery modules connected in series is large, and inconsistencies between batteries frequently occur during actual operation. In actual operation and maintenance, manual inspection methods are usually used, employing additional balancing devices and equipment, which are labor-intensive, inefficient, and costly in terms of personnel and time.

[0003] Therefore, there is a need for a series direction reconfiguration method for dynamically reconfigurable energy storage systems that can achieve dynamic reconfiguration of the series direction, eliminate the difference in charge between battery modules, achieve fast and efficient battery module balancing, and improve the service life and consistency of the energy storage system. Summary of the Invention

[0004] This invention addresses the shortcomings of existing energy storage systems, such as the need for passive balancing when series batteries become unbalanced, the requirement for additional balancing devices and equipment, low balancing efficiency, and significant circuit switching losses. It provides a series direction reconfiguration method for dynamically reconfigurable energy storage systems that enables dynamic reconfiguration of the series direction, eliminates differences in battery charge between modules, achieves rapid and efficient battery module balancing, and improves the lifespan and consistency of the energy storage system.

[0005] The series directional reconfiguration method based on a dynamically reconfigurable energy storage system according to the present invention includes the following steps: S1. Construct the battery system as a dynamically reconfigurable battery system; S2. Arrange the m battery modules in the battery system in descending order according to their initial SOC values; S3. Discharge the first m-1 battery modules: Disconnect the battery module corresponding to the last initial SOC value and discharge the battery modules corresponding to the first m-1 initial SOC values; calculate the average SOC of the battery system in real time during the discharge process, and obtain the instantaneous SOC values ​​of the battery modules corresponding to the first m-1 initial SOC values ​​in real time. If the minimum instantaneous SOC value SOC_min is less than or equal to the current average SOC value of the battery system, stop discharging and take the instantaneous SOC values ​​of the m battery modules at this time as the SOC value of one discharge; calculate the standard deviation of SOC of the m battery modules in real time. S4. Sort the m battery modules after discharge in ascending order according to their current SOC discharge value. S5. Charge the first m-1 battery modules: Disconnect the battery module corresponding to the last SOC discharge value and charge the battery modules corresponding to the first m-1 SOC discharge values; calculate the average SOC of the battery system in real time during charging, and obtain the instantaneous SOC value of the battery modules corresponding to the first m-1 SOC discharge values ​​in real time. If the maximum value of the instantaneous SOC value is greater than or equal to the current average SOC of the battery system, stop discharging and take the instantaneous SOC value of the m battery modules at this time as the SOC charge value; calculate the standard deviation of SOC of the m battery modules in real time. S6. Repeat S2-S5. In any charging or discharging process, if the SOC standard deviation is less than or equal to the standard deviation threshold, it is considered that the SOC between battery modules tends to be consistent, and charging or discharging is stopped.

[0006] Further: In S1, the construction process of the dynamically reconfigurable battery system is as follows: The preset upper and lower limits of the allowable SOC of the battery module, the upper and lower limits of the voltage, and the SOC standard deviation threshold are set.

[0007] Further: In S3, when discharging, the average SOC of the battery system is the average SOC of the remaining initial SOC values ​​after removing the lowest and highest initial SOC values ​​in the descending order sequence. The formula for calculating the average SOC is as follows: ; In the formula, SOC_mean is the average SOC, m is the number of battery modules connected in series, i is the sorting position of the battery module, and SOC_descend is the SOC sequence after descending order.

[0008] Furthermore: In S3, the formula for calculating the standard deviation of SOC is as follows: ; In the formula, SOC_std is the standard deviation of SOC, m is the number of battery modules connected in series, and i is the ranking of the battery module. The average SOC of all cells is calculated using the following formula: .

[0009] Furthermore: In S3, when the minimum instantaneous SOC value SOC_min is less than or equal to the average SOC value of the current battery system, or when any SOC exceeds the upper and lower limits of the allowable use and the upper and lower limits of the voltage, the discharge is stopped.

[0010] Furthermore: In S5, charging stops when the maximum instantaneous SOC value SOC_max is greater than or equal to the average SOC value of the current battery system or when any SOC exceeds the upper and lower limits of the allowable use and the upper and lower limits of the voltage.

[0011] The series directional reconfiguration method based on a dynamically reconfigurable energy storage system according to the present invention includes the following steps: S1. Construct the battery system as a dynamically reconfigurable battery system; S2. Arrange the m battery modules in the battery system in ascending order according to their initial SOC values; S3. Charge the first m-1 battery modules: Disconnect the battery module corresponding to the last initial SOC value and charge the battery modules corresponding to the first m-1 initial SOC values; calculate the average SOC of the battery system in real time during the charging process, and obtain the instantaneous SOC values ​​of the battery modules corresponding to the first m-1 initial SOC values ​​in real time. If the maximum value of the instantaneous SOC value is greater than or equal to the current average SOC value of the battery system, stop discharging and take the instantaneous SOC values ​​of the m battery modules at this time as the SOC value for one charge; calculate the standard deviation of SOC of the m battery modules in real time. S4. Sort the m battery modules after charging in descending order according to their current SOC (State of Charge) value after a single charge. S5. Discharge the first m-1 battery modules: Disconnect the battery module corresponding to the last SOC (State of Charge) charge value, and discharge the battery modules corresponding to the first m-1 SOC charge values. Calculate the average SOC of the battery system during the discharge process in real time, and obtain the instantaneous SOC values ​​of the battery modules corresponding to the first m-1 SOC charge values ​​in real time. If the minimum instantaneous SOC value (SOC_min) is less than or equal to the current average SOC of the battery system, stop discharging and use the instantaneous SOC values ​​of the m battery modules at this time as the SOC discharge value. Calculate the standard deviation of the SOC of the m battery modules in real time. S6. Repeat S2-S5. In any charging or discharging process, if the SOC standard deviation is less than or equal to the standard deviation threshold, it is considered that the SOC between battery modules tends to be consistent, and charging or discharging is stopped.

[0012] The beneficial effects of this invention are: (1) The series direction reconfiguration method based on a dynamically reconfigurable energy storage system described in this invention is a method that can realize dynamic reconfiguration of the series direction, thereby eliminating the difference in charge between battery modules. This invention can utilize the inherent components of the dynamically reconfigurable energy storage system to achieve fast and efficient battery module balancing, eliminate inconsistencies, and improve the service life and consistency of the energy storage system.

[0013] (2) This invention can make full use of the electronic switching devices of the dynamically reconfigurable energy storage system to achieve battery module balancing in the series direction. By reasonably controlling the switching components, the energy storage system can be charged and discharged without changing the existing system hardware, thus achieving balancing between battery modules. This method has fewer switching operations, reduces switching losses, eliminates the need for frequent reconfiguration, reduces control difficulty, and has a short running time and high balancing efficiency. Attached Figure Description

[0014] Figure 1 It is a battery system consisting of four batteries; Figure 2 It shows the changes in the SOC of the four batteries during the entire series reconfiguration process; Figure 3 This shows the changes in the standard deviation of the SOC of the four batteries; Figure 4 This shows the variation in the SOC range of the four batteries; Figure 5 It shows the changes in the SOC of the ten batteries during the entire series reconfiguration process; Figure 6 This shows the variation of the standard deviation of the SOC of ten batteries; Figure 7 This shows the variation in the SOC range of ten batteries. Detailed Implementation

[0015] The following are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The embodiments described below are only for explaining the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the scope of the claims. The embodiments of the present invention are described in detail below. In order to facilitate the description of the present invention and simplify the description, the technical terms used in the specification of the present invention should be interpreted broadly, including but not limited to conventional alternatives not mentioned in this application, as well as direct and indirect implementation methods.

[0016] Example 1 Combination Figures 1-4 This embodiment describes a series directional reconfiguration method based on a dynamically reconfigurable energy storage system, comprising the following steps: S1. Construct the battery system as a dynamically reconfigurable battery system; S2. Arrange the m battery modules in the battery system in descending order according to their initial SOC values; S3. Discharge the first m-1 battery modules: Disconnect the battery module corresponding to the last initial SOC value and discharge the battery modules corresponding to the first m-1 initial SOC values; calculate the average SOC of the battery system in real time during the discharge process, and obtain the instantaneous SOC values ​​of the battery modules corresponding to the first m-1 initial SOC values ​​in real time. If the minimum instantaneous SOC value SOC_min is less than or equal to the current average SOC value of the battery system, stop discharging and take the instantaneous SOC values ​​of the m battery modules at this time as the SOC value of one discharge; calculate the standard deviation of SOC of the m battery modules in real time. S4. Sort the m battery modules after discharge in ascending order according to their current SOC discharge value. S5. Charge the first m-1 battery modules: Disconnect the battery module corresponding to the last SOC discharge value and charge the battery modules corresponding to the first m-1 SOC discharge values; calculate the average SOC of the battery system in real time during charging, and obtain the instantaneous SOC value of the battery modules corresponding to the first m-1 SOC discharge values ​​in real time. If the maximum value of the instantaneous SOC value is greater than or equal to the current average SOC of the battery system, stop discharging and take the instantaneous SOC value of the m battery modules at this time as the SOC charge value; calculate the standard deviation of SOC of the m battery modules in real time. S6. Repeat S2-S5. In any charging or discharging process, if the SOC standard deviation is less than or equal to the standard deviation threshold, it is considered that the SOC between battery modules tends to be consistent, and charging or discharging is stopped.

[0017] As shown Figure 1 in the figure, the battery system consists of four batteries, and each battery is equipped with two switches. Switch S is the access switch, and B is the bypass switch. When the battery is connected to the circuit, S = 1 and B = 0; when the battery is disconnected from the circuit, S = 0 and B = 1. The access and disconnection of the battery from the main circuit are achieved through switch S and switch B. The upper and lower limits of the allowable SOC of the battery module are set as [10%, 90%], and the upper and lower limits of the voltage are [11V, 14V].

[0018] Let the initial SOC of the four batteries be [B1 = 63.3%, B2 = 69%, B3 = 67%, B4 = 59%], and the set SOC standard deviation threshold SOC_std_threshold = 0.2%; first, perform discharge. The initial SOC is sorted in descending order to obtain a new descending-ordered SOC sequence SOC_descend = [B2 = 69%, B3 = 67%, B1 = 63.3%, B4 = 59%], and the average value SOC_mean = 65.15% of SOC_descend(2:m - 1) is calculated; SOC_descend(2:m - 1) represents the values from the 2nd to the (m - 1)th in the SOC_descend sequence, that is, after removing the maximum SOC and the minimum SOC, the remaining SOC values.

[0019] Discharge the battery modules corresponding to the first 3 SOCs in SOC_descend, that is, discharge batteries B1, B2, and B3, and battery B4 exits the main circuit. During the discharge process, the SOC_mean of batteries B1 and B3 should be calculated in real time, and the size relationship between the lowest SOC (SOC_min = 59%) and SOC_mean should be judged in real time.

[0020] When SOC_min < SOC_mean, continue to discharge. During the discharge process, the SOC values corresponding to each battery module and the standard deviation SOC_std of each SOC value should be calculated in real time.

[0021] When SOC_min >= SOC_mean, stop discharging and switch to charging. At this time, the SOC of the four batteries is [B2 = 57.1%, B3 = 62.8%, B1 = 60.8%, B4 = 59%]; When charging, the battery modules are sorted in ascending order according to SOC to obtain a new ascending-ordered SOC sequence SOC_ascend = [B2 = 57.1%, B4 = 59%, B1 = 60.8%, B3 = 62.8%], and the average value SOC_mean = 59.9% of SOC_ascend(2:m - 1) is calculated; The battery modules corresponding to the first three SOCs in SOC_ascend are charged, namely batteries B1, B2, and B4, while battery B3 is removed from the main circuit. During the charging process, SOC_mean is calculated in real time, and the relationship between the highest SOC (SOC_max) and SOC_mean is determined in real time. When SOC_max > SOC_mean, charging continues. During charging, the SOC value of each battery module and the standard deviation SOC_std of each SOC value are calculated in real time.

[0022] When SOC_max <= SOC_mean, charging stops and discharge begins. At this point, the SOCs of the four batteries are [B2 = 60%, B3 = 62.8%, B1 = 63.7%, B4 = 61.9%]. Repeat steps 2-9. When SOC_std <= SOC_std_threshold, it is considered that the SOC between battery modules is consistent, and charging and discharging are stopped.

[0023] Throughout the reconstruction process, the SOC range (SOC_max - SOC_min) at each time step was calculated, such as... Figure 4 As shown, it can be seen that as the reconstruction proceeds, the SOC range of the four batteries gradually decreases and the SOC tends to be consistent, which is a very good result.

[0024] Example 2 This embodiment, in conjunction with Example 1, discloses a series directional reconfiguration method based on a dynamically reconfigurable energy storage system, comprising the following steps: S1. Construct the battery system as a dynamically reconfigurable battery system; S2. Arrange the m battery modules in the battery system in ascending order according to their initial SOC values; S3. Charge the first m-1 battery modules: Disconnect the battery module corresponding to the last initial SOC value and charge the battery modules corresponding to the first m-1 initial SOC values; calculate the average SOC of the battery system in real time during the charging process, and obtain the instantaneous SOC values ​​of the battery modules corresponding to the first m-1 initial SOC values ​​in real time. If the maximum value of the instantaneous SOC value is greater than or equal to the current average SOC value of the battery system, stop discharging and take the instantaneous SOC values ​​of the m battery modules at this time as the SOC value for one charge; calculate the standard deviation of SOC of the m battery modules in real time. S4. Sort the m battery modules after charging in descending order according to their current SOC (State of Charge) value after a single charge. S5. Discharge the first m-1 battery modules: Disconnect the battery module corresponding to the last SOC one-time charge value, and discharge the battery modules corresponding to the first m-1 SOC one-time charge values; calculate the average SOC of the battery system in real time during the discharge process, and obtain the instantaneous SOC values of the battery modules corresponding to the first m-1 SOC one-time charge values in real time; if the minimum value SOC_min of the instantaneous SOC values is less than or equal to the average SOC of the current battery system, stop discharging, and use the instantaneous SOC values of the m battery modules at this time as the SOC one-time discharge values; calculate the SOC standard deviation of the m battery modules in real time; S6. Repeat S2-S5. During any charging or discharging process, if the SOC standard deviation is less than or equal to the standard deviation threshold, it is considered that the SOCs between the battery modules tend to be consistent, and stop charging or discharging.

[0025] Embodiment 3 Combined with Embodiment 1 and Figures 5-7 Describe this embodiment. A series direction reconstruction method based on a dynamically reconfigurable energy storage system disclosed in this embodiment. Assume that the initial SOCs of ten batteries are [B1 = 83.1%, B2 = 73.2%, B3 = 63.3%, B4 = 66.3%, B5 = 68.3%, B6 = 65%, B7 = 60%, B8 = 74%, B9 = 79%, B10 = 40%], and set the SOC standard deviation threshold SOC_std_threshold = 1%; first perform discharging. Arrange the initial SOCs in descending order to obtain a new descending-ordered SOC sequence SOC_descend = [B1 = 83.1%, B9 = 79%, B8 = 74%, B2 = 73.2%, B5 = 68.3%, B4 = 66.2%, B6 = 65%, B3 = 63.3%, B7 = 60%, B10 = 40%], and calculate the average value SOC_mean = 68.625% of SOC_descend(2:m-1); Discharge the battery modules corresponding to the first 9 SOCs in SOC_descend, that is, battery B10 exits the main circuit, and discharge the other batteries. During the discharge process, calculate SOC_mean in real time, and judge the magnitude relationship between the lowest SOC (SOC_min = 40%) and SOC_mean in real time.

[0026] When SOC_min < SOC_mean, continue discharging. During the discharge process, calculate the SOC values corresponding to each battery module and the standard deviation SOC_std of each SOC value in real time.

[0027] When SOC_min >= SOC_mean, discharging stops and charging begins. At this point, the SOCs of the ten batteries are [B1=54.47%, B2=44.57%, B3=34.63%, B4=37.57%, B5=39.67%, B6=36.37%, B7=31.37%, B8=45.37%, B9=50.37%, B10=40%]; During charging, the battery modules are sorted in ascending order according to their State of Charge (SOC), resulting in a new ascending SOC sequence: SOC_ascend = [B7=31.37%, B3=34.67%, B6=36.37%, B4=37.57%, B5=39.67%, B10=40%, B2=44.57%, B8=45.37%, B9=50.37%, B1=54.47%]. The average value of SOC_ascend(2:m-1) is calculated as SOC_mean = 41.07%. The battery modules corresponding to the first 9 SOCs in SOC_ascend are charged, meaning battery B1 exits the main circuit and the other batteries are discharged. During the charging process, SOC_mean is calculated in real time, and the relationship between the highest SOC (SOC_max) and SOC_mean is determined in real time. When SOC_max > SOC_mean, charging continues. During charging, the SOC value of each battery module and the standard deviation SOC_std of each SOC value are calculated in real time.

[0028] When SOC_max <= SOC_mean, charging stops and discharge begins. At this point, the SOCs of the ten batteries are [B1=54.47%, B2=63.53%, B3=53.63%, B4=56.53%, B5=58.63%, B6=55.33%, B7=50.33%, B8=64.33%, B9=69.33%, B10=58.96%].

[0029] Repeat steps 2-9. When SOC_std <= SOC_std_threshold, it is considered that the SOC between battery modules is consistent, and charging and discharging are stopped.

[0030] Throughout the reconstruction process, the SOC range (SOC_max - SOC_min) at each time step was calculated, such as... Figure 7 As shown, it can be seen that as the reconstruction proceeds, the SOC range of the ten batteries gradually decreases and the SOC tends to be consistent, which is a very good result.

Claims

1. A series directional reconfiguration method based on a dynamically reconfigurable energy storage system, characterized in that, Includes the following steps: S1. Construct the battery system as a dynamically reconfigurable battery system; S2. Arrange the m battery modules in the battery system in descending order according to their initial SOC values; S3. Discharge the first m-1 battery modules: Disconnect the battery module corresponding to the last SOC initial value and discharge the battery modules corresponding to the first m-1 SOC initial values; calculate the average SOC of the battery system in real time during the discharge process, and obtain the instantaneous SOC value of the battery module corresponding to the first m-1 SOC initial values ​​in real time. If the minimum instantaneous SOC value SOC_min is less than or equal to the current average SOC of the battery system, stop discharging and take the instantaneous SOC value of the m battery modules at this time as the SOC value of one discharge. Real-time calculation of the SOC standard deviation of m battery modules; S4. Sort the m battery modules after discharge in ascending order according to their current SOC discharge value. S5. Charge the first m-1 battery modules: Disconnect the battery module corresponding to the last SOC discharge value and charge the battery modules corresponding to the first m-1 SOC discharge values; calculate the average SOC of the battery system in real time during the charging process, and obtain the instantaneous SOC value of the battery module corresponding to the first m-1 SOC discharge values ​​in real time. If the maximum value of the instantaneous SOC value is greater than or equal to the current average SOC of the battery system, stop discharging and take the instantaneous SOC value of the m battery modules at this time as the SOC charge value. Real-time calculation of the SOC standard deviation of m battery modules; S6. Repeat S2-S5. In any charging or discharging process, if the SOC standard deviation is less than or equal to the standard deviation threshold, it is considered that the SOC between battery modules tends to be consistent, and charging or discharging is stopped.

2. The series directional reconfiguration method based on a dynamically reconfigurable energy storage system according to claim 1, characterized in that, In S1, the construction process of the dynamically reconfigurable battery system is as follows: The preset upper and lower limits of the allowable SOC of the battery module, the upper and lower limits of the voltage, and the SOC standard deviation threshold are set.

3. The series directional reconfiguration method based on a dynamically reconfigurable energy storage system according to claim 1, characterized in that, In S3, when discharging, the average SOC of the battery system is the average SOC of the remaining initial SOC values ​​after removing the lowest and highest initial SOC values ​​in the descending order sequence. The formula for calculating the average SOC is as follows: ； In the formula, SOC_mean is the average SOC, m is the number of battery modules connected in series, i is the sorting position of the battery module, and SOC_descend is the SOC sequence after descending order.

4. The series directional reconfiguration method based on a dynamically reconfigurable energy storage system according to claim 1, characterized in that, In S3, the formula for calculating the standard deviation of SOC is as follows: ； In the formula, SOC_std is the standard deviation of SOC, m is the number of battery modules connected in series, and i is the ranking of the battery module. The average SOC of all cells is calculated using the following formula: 。 5. The series directional reconfiguration method based on a dynamically reconfigurable energy storage system according to claim 1, characterized in that, In S3, discharge stops when the minimum instantaneous SOC value, SOC_min, is less than or equal to the average SOC of the current battery system, or when any SOC exceeds the upper or lower limits of the allowable use and the upper or lower limits of the voltage.

6. The series directional reconfiguration method based on a dynamically reconfigurable energy storage system according to claim 1, characterized in that, In S5, charging stops when the maximum instantaneous SOC value, SOC_max, is greater than or equal to the average SOC of the current battery system, or when any SOC exceeds the upper or lower limits of the allowable usage and the upper or lower limits of the voltage.

7. A series directional reconfiguration method based on a dynamically reconfigurable energy storage system, characterized in that, Includes the following steps: S1. Construct the battery system as a dynamically reconfigurable battery system; S2. Arrange the m battery modules in the battery system in ascending order according to their initial SOC values; S3. Charge the first m-1 battery modules: Disconnect the battery module corresponding to the last initial SOC value and charge the battery modules corresponding to the first m-1 initial SOC values; calculate the average SOC value of the battery system in real time during the charging process, and obtain the instantaneous SOC value of the battery modules corresponding to the first m-1 initial SOC values ​​in real time. If the maximum value of the instantaneous SOC value is greater than or equal to the current average SOC value of the battery system, stop discharging and take the instantaneous SOC value of the m battery modules at this time as the SOC value of one charge. Real-time calculation of the SOC standard deviation of m battery modules; S4. Sort the m battery modules after charging in descending order according to their current SOC (State of Charge) value after a single charge. S5. Discharge the first m-1 battery modules: Disconnect the battery module corresponding to the last SOC charge value and discharge the battery modules corresponding to the first m-1 SOC charge values; calculate the average SOC of the battery system in real time during the discharge process and obtain the instantaneous SOC value of the battery modules corresponding to the first m-1 SOC charge values ​​in real time; if the minimum instantaneous SOC value SOC_min is less than or equal to the current average SOC of the battery system, stop discharging and take the instantaneous SOC value of the m battery modules at this time as the SOC discharge value. Real-time calculation of the SOC standard deviation of m battery modules; S6. Repeat S2-S5. In any charging or discharging process, if the SOC standard deviation is less than or equal to the standard deviation threshold, it is considered that the SOC between battery modules tends to be consistent, and charging or discharging is stopped.

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