Lithium battery energy storage system and fault detection method

Abstract

The present application belongs to the field of lithium batteries, and specifically relates to a lithium battery energy storage system and a fault detection method, which comprises N groups of series battery packs, M parallel single batteries in each battery pack, two battery packs forming a battery group, two battery packs in the battery group being connected through M nodes to form a symmetric loop topology structure. A current meter is arranged at the middle position of each group of parallel battery packs and between the first battery and the last battery of the two battery packs in the battery group; a voltage meter is arranged between every two battery packs. The present application uses the difference in current ratio and the difference in adjacent voltage to determine and locate the position of the faulty battery in the form of the symmetric loop topology structure, reduces the number of sensors, and solves the problem of complicated detection in the process of large-scale battery integration.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of lithium batteries, and particularly relates to a lithium battery energy storage system and a fault detection method. BACKGROUND

[0002] Since a lithium battery energy storage system needs to integrate a large number of lithium batteries, a conventional topology structure adopts a traditional series or parallel mode, and in the process of large-scale battery integration, a large number of sensors need to be used to help locate and monitor the safety problems of the energy storage system. For example, for a conventional topology structure of 64 series-parallel combinations, 64 current sensors need to be configured, and then the current values detected can be used to determine which batteries in the structure have faults. SUMMARY

[0003] The application aims to provide a lithium battery energy storage system and a fault detection method for a lithium battery energy storage system topology structure, and solve the problem of complicated fault detection in the process of large-scale battery integration.

[0004] The application is implemented in the following manner,

[0005] A lithium battery energy storage system comprises:

[0006] N groups of series battery packs, each battery pack comprising M parallel single batteries, two battery packs forming a battery group, and the two battery packs in the battery group being connected through M nodes to form a symmetrical loop topology structure.

[0007] Further, a current meter is arranged at the middle position of each group of parallel battery packs and between the first battery and the last battery of the two battery packs in the battery group, and a voltage meter is arranged between each two battery packs.

[0008] Further, the application further comprises:

[0009] A fault battery pack locating module is configured to analyze the correlation between the battery packs according to the voltage signals collected by the voltage meters and determine the state of the battery packs according to the correlation analysis result.

[0010] A fault battery locating module is configured to determine the specific battery in the battery pack that has a fault by the value of the current meter of the battery pack.

[0011] Further, the fault battery pack locating module is further configured to establish a battery pack fault corresponding relationship corresponding to the correlation coefficient generated in various situations when the battery pack has a fault, find the corresponding battery pack that has a fault from the fault analysis corresponding relationship according to the correlation coefficient obtained from the voltage value, and identify the battery pack that has a short circuit fault by using different correlation coefficient changes.

[0012] Further, the fault battery positioning module establishes a battery fault corresponding table according to different currents of the ammeters corresponding to the short-circuit faults of the batteries at different positions in the battery pack, and judges the battery that has the fault by using the reading of the ammeter to correspond to the battery fault corresponding relation.

[0013] A fault detection method of a lithium battery energy storage system, each two battery packs form a battery group, current meters are arranged at the middle positions of each group of parallel battery packs, and the first battery and the last battery of the two battery packs in the battery group;

[0014] The sum of voltages between two adjacent battery packs is measured by a voltmeter;

[0015] According to the signal of the voltmeter, the state of the battery pack is judged by correlation analysis;

[0016] The battery pack with an abnormal state is judged to be the battery pack in which the specific battery that has the fault is located by the value of the ammeter of the battery pack.

[0017] Further, the correlation analysis includes analyzing the correlation between each battery pack and other battery packs.

[0018] Further, the correlation coefficient is obtained by using formula (1) for the correlation analysis:

[0019]

[0020] Wherein, according to the ratio of the covariance of two variables X and Y to the standard deviation of the two variables, the variable is the measured voltage value, the correlation degree of the vector is judged by the value range, cov(X, Y) is the covariance of X and Y; σ X is the covariance of X; σ Y is the covariance of Y.

[0021] Further, the battery pack fault corresponding relation is established according to the correlation coefficient corresponding to the fault of the battery pack in various cases, the battery pack that has the fault is found from the fault analysis corresponding relation according to the correlation coefficient obtained from the voltage value, and the battery pack that has the short-circuit fault is identified by using different correlation coefficient changes.

[0022] Further, the battery fault corresponding table is established according to the different currents of the ammeters corresponding to the short-circuit faults of the batteries at different positions in the battery pack, and the battery that has the fault is judged by using the reading of the ammeter to correspond to the battery fault corresponding relation.

[0023] Compared with the prior art, the present application has the beneficial effects that:

[0024] In order to reduce the application of the sensor in the energy storage system, the application uses the difference of current ratio and the difference of adjacent voltage to determine the position of the fault battery through the symmetrical loop topology. The lithium battery pack constructed in the embodiment provided by the application is of the size of 8x8 (8 series 8 parallel), and 64 current sensors are needed to be configured according to the traditional topology. 15 sensors, 8 ammeters and 7 voltmeters can be used to monitor the safety of the energy storage system by using the application. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A lithium battery pack 8x8 topology diagram provided by the embodiment of the application, wherein the large circle is a voltmeter and the small circle is an ammeter;

[0026] Figure 2 A flow chart of a fault detection method of a lithium battery energy storage system provided by the embodiment of the application;

[0027] Figure 3 A correlation analysis diagram for positioning the battery pack based on the correlation coefficient provided by the embodiment of the application;

[0028] Figure 4 A diagram for positioning the fault current based on the ammeter provided by the embodiment of the application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below in combination with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0030] A lithium battery energy storage system, comprising:

[0031] N groups of series battery packs, each battery pack has M parallel single batteries, two battery packs form a battery pack, and the two battery packs in the battery pack are connected through M nodes to form a symmetrical loop topology.

[0032] Wherein M and N are both even numbers, and when increased, the even numbers are increased, and the ammeters are arranged between the middle position of each group of parallel battery packs and the first battery and the last battery of the two battery packs in the battery pack; the voltmeter is arranged between every two battery packs.

[0033] Further comprising a fault battery pack positioning module, which analyzes the correlation between the battery packs according to the voltage signals collected by the voltmeter, and determines the state of the battery pack according to the correlation analysis result;

[0034] The fault battery positioning module judges the specific battery in the battery pack that has a fault according to the value of the ammeter of the battery pack that has an abnormal state.

[0035] The fault battery positioning module establishes a battery fault correspondence table according to the different currents of the ammeters of the batteries in different positions in the battery pack when the batteries have a short circuit fault, and judges the battery that has a fault by using the reading of the ammeter to correspond to the battery fault correspondence table.

[0036] As shown in Figure 1 The lithium battery pack is constructed in a structure of 8x8 (8 series and 8 parallel), and the coordinates of each battery are numbered according to rows and columns. The connection between two battery packs in each battery pack needs to form 8 nodes, and only one node is needed to connect between each group of battery packs. Only two ammeters are needed to be set in each group of battery packs, and no sensor needs to be added when parallel batteries are added. When series battery packs are added, only voltage sensors and two ammeters need to be added.

[0037] In this embodiment, 15 sensors, i.e. 8 ammeters and 7 voltage meters, are used to monitor the safety of the energy storage system through the topology of the battery of the application.

[0038] As shown in Figure 2 The application also provides a fault detection method for a lithium battery energy storage system

[0039] First, the lithium batteries are grouped according to the topology, i.e. grouped according to battery packs and battery groups, and the row and column coordinates of each battery are numbered.

[0040] Each two battery packs form a battery group, and ammeters are arranged between the middle positions of each group of parallel battery packs and between the first battery and the last battery of the two battery packs in the battery group.

[0041] The sum of the voltages between the adjacent two battery packs is measured by the voltage meter.

[0042] According to the signal of the voltage meter, the state of the battery pack is judged by correlation analysis. In this embodiment, the 8 parallel batteries form a group, and only the signal of the voltage meter is detected when the lithium battery is in a daily working state, and the state of the current lithium battery group is judged by the method of correlation analysis.

[0043] The battery pack with abnormal state is judged to have a specific battery fault by the value of the ammeter of the battery pack. When the voltage meter signal is abnormal, the specific position of the battery pack with fault is judged by the data state. If the data is not abnormal by correlation analysis, the lithium battery pack is in normal working state. When the voltage data between the battery packs is not correlated by correlation analysis, it indicates that there is a battery pack in abnormal state. As shown in Figure 3 When all the batteries are in normal working state, the correlation coefficient of the voltage signals between the battery packs is 1, but when a short circuit fault occurs, the corresponding correlation coefficient will change. When each battery pack has a fault, the corresponding correlation coefficient is different, so different correlation coefficient changes are used to identify the specific battery pack with short circuit fault. When the specific battery pack with fault is obtained, the ammeter of the battery pack is used to judge the specific battery with fault in the battery pack with fault. Figure 4 When the batteries at different positions in the battery pack have short circuit faults, the readings of the ammeters are different, as shown in Figure 4 Therefore, the readings of the ammeters can be used to judge which specific battery has a fault. Eight parallel battery packs form one battery pack, and the fault battery is located at the same time.

[0044] In this embodiment, the formula used in correlation analysis is:

[0045] Formula 1:

[0046] Formula 1 represents the ratio of the covariance of X and Y to the standard deviation of the two variables. The variable here refers to the voltage value measured by the voltage meter, and the correlation degree of the vector is judged by the value range. cov(X, Y) - X, Y covariance; σ X - X covariance; σ Y - Y covariance. For example, as shown in Figure 3 When the correlation coefficient of the voltage is 1, the battery is in normal working state, and when the correlation coefficient is less than 1, the battery pack is in short circuit fault state.

[0047] The method of the application can also: when the battery pack has a fault in various cases, the corresponding correlation coefficient is established to correspond to the battery pack fault, and when the correlation coefficient obtained from the voltage value is found from the fault analysis corresponding relationship to find the corresponding battery pack with fault, different correlation coefficient changes are used to identify the specific battery pack with short circuit fault.

[0048] And according to the different currents of the ammeters of the batteries at different positions in the battery pack when the batteries have short circuit faults, a battery fault corresponding table is established, and the readings of the ammeters are used to correspond to the battery fault corresponding relationship to judge the battery with fault.

[0049] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A lithium battery energy storage system, characterized by, include: N sets of series-connected battery packs, each battery pack contains M parallel single cells, two battery packs form a battery group, and the two battery packs in the battery group are connected through M nodes to form a symmetrical loop topology. An ammeter is placed in the middle of each group of parallel battery packs, and between the first and last cells of two battery packs in the battery pack. A voltmeter is installed between every two battery packs; It also includes: a faulty battery pack location module, which analyzes the correlation between battery packs based on the voltage signals collected by the voltmeter, and determines the status of the battery packs based on the correlation analysis results; The faulty battery location module identifies the specific faulty battery in a battery pack by measuring the ammeter readings of that pack.

2. The lithium battery energy storage system of claim 1, wherein, The faulty battery pack location module is also used to establish a battery pack fault correspondence relationship by identifying the correlation coefficients of battery pack faults under various conditions. When the corresponding faulty battery pack is found from the fault analysis correspondence based on the correlation coefficient obtained from the voltage value, the specific battery pack that has experienced a short circuit fault is identified by using different changes in the correlation coefficient.

3. The lithium battery energy storage system of claim 1, wherein, The faulty battery location module establishes a battery fault correspondence table based on the different current readings of the battery meter corresponding to short-circuit faults in batteries at different locations in the battery pack. It uses the ammeter readings to match the battery fault correspondence to determine the faulty battery.

4. A method of fault detection for a lithium battery energy storage system as claimed in any one of claims 1 to 3, characterised in that, Each pair of battery packs forms a battery group. An ammeter is installed in the middle of each group of parallel battery packs, and between the first and last battery of each pair of battery packs in the battery group. The sum of the voltages between two adjacent battery packs is measured using a voltmeter; The status of the battery pack is determined by correlation analysis based on the voltmeter signal. For battery packs with abnormal conditions, the specific battery that has failed can be determined by the reading of the ammeter in that battery pack.

5. The fault detection method according to claim 4, characterized in that, The correlation analysis includes analyzing the correlation between each battery pack and other battery packs.

6. The fault detection method according to claim 4 or 5, characterized in that, The correlation coefficient was obtained by performing the correlation analysis using formula (1): （1） Wherein, according to the ratio of the covariance of X, Y two variables and the standard deviation of two variables, the variable is the measured voltage value, the correlation degree of the vector is judged by the value range, is the covariance of X, Y; is the covariance of X; is the covariance of Y.

7. The fault detection method according to claim 4, characterized in that, By establishing a correlation coefficient for battery pack failures under various conditions, a corresponding relationship between battery pack failures is established. When the correlation coefficient obtained based on the voltage value is used to find the corresponding faulty battery pack from the fault analysis relationship, the specific battery pack that has experienced a short circuit fault is identified by using different changes in the correlation coefficient.

8. The fault detection method according to claim 4, characterized in that, A battery fault correspondence table is established based on the different current readings of the battery meters corresponding to short-circuit faults in batteries at different locations in the battery pack. The faulty battery can be identified by mapping the ammeter readings to the corresponding battery faults.

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