Fault battery detection method, electronic equipment and storage medium

Abstract

The invention provides a fault battery detection method, electronic equipment and a storage medium, which can be applied to the technical field of fault detection of an energy storage system. The method comprises the steps that in response to the fact that M single batteries in a battery cluster are not in an equilibrium state, voltage change values of the M single batteries in a target time period are obtained, and the target time period is determined according to a single voltage sampling period; in response to the fact that the voltage change values of the N cascaded battery monomers in the battery cluster are all smaller than zero and the voltage change values of the M-N battery monomers in the battery cluster are all larger than zero, obtaining a first statistical voltage change value according to the voltage change values of the N battery monomers, and obtaining a second statistical voltage change value according to the voltage change values of the M-N battery monomers; n is less than M; and according to a difference value between the second statistical voltage change value and the first statistical voltage change value and a predetermined voltage change threshold, obtaining a detection result used for indicating that the battery cluster is in a fault state or a normal state.

Description

Technical Field

[0001] The present invention relates to the technical field of fault detection of energy storage systems, and more specifically, to a faulty battery detection method, electronic equipment, and storage medium. Background Art

[0002] Lithium battery electrochemical energy storage systems, with their technical advantages such as fast response, high energy density and long cycle life, have gradually become an important support for curbing fluctuations in new energy and improving the flexibility of the power grid.

[0003] In related technologies, the fault detection strategy adopted by lithium battery energy storage systems has low accuracy. Summary of the Invention

[0004] In view of this, the present invention provides a faulty battery detection method, an electronic device, and a storage medium.

[0005] One aspect of the present invention provides a faulty battery detection method, comprising: in response to M battery cells in a battery cluster not being in a balanced state, obtaining voltage change values ​​of each of the M battery cells within a target time period, wherein the target time period is determined based on a single voltage sampling cycle, the balanced state indicates voltage regulation of the battery cluster using a predetermined voltage regulation strategy, and M is a positive integer; in response to N cascaded battery cells in the battery cluster having voltage change values ​​each less than zero and MN battery cells in the battery cluster having voltage change values ​​each greater than zero, obtaining a first statistical voltage change value based on the voltage change values ​​of the N battery cells and obtaining a second statistical voltage change value based on the voltage change values ​​of the MN battery cells, wherein N<M and N is a positive integer; and obtaining a detection result indicating whether the battery cluster is in a faulty state or a normal state based on a difference between the second statistical voltage change value and the first statistical voltage change value and a predetermined voltage change threshold.

[0006] According to an embodiment of the present invention, the starting moment of the target time period is the moment corresponding to the sum of the current sampling moment and the preset delay, and the ending moment of the target time period is the previous sampling moment of the current sampling moment; or the starting moment of the target time period is the current sampling moment, and the ending moment of the target time period is the previous sampling moment of the current sampling moment; wherein, obtaining the voltage change value of each of the M battery cells within the target time period includes: for any battery cell among the M battery cells, obtaining a first voltage value of the battery cell at the starting moment and a second voltage value at the ending moment; and obtaining the voltage change value of the battery cell based on the first voltage value and the second voltage value.

[0007] According to an embodiment of the present invention, the preset delay is greater than a single voltage sampling period.

[0008] According to an embodiment of the present invention, the first statistical voltage change value is an average of the voltage change values ​​of N cascaded battery cells, and the second statistical voltage change value is an average of the voltage change values ​​of MN battery cells. Wherein, based on the difference between the second statistical voltage change value and the first statistical voltage change value and a predetermined voltage change threshold, a detection result indicating that the battery cluster is in a faulty state or a normal state is obtained, including: when the absolute value of the difference is greater than or equal to the predetermined voltage change threshold, obtaining a detection result indicating that the battery cluster is in a faulty state; when the absolute value of the difference is less than the predetermined voltage change threshold, obtaining a detection result indicating that the battery cluster is in a normal state.

[0009] According to an embodiment of the present invention, the method further includes: in response to obtaining a detection result indicating that the battery cluster is in a fault state, determining that the N cascaded battery cells are short-circuit fault batteries.

[0010] According to an embodiment of the present invention, the predetermined voltage change threshold is determined based on the following operations: using the loop current equation to obtain the voltage drop value of the mth battery cell in the battery cluster and the average voltage increase value of the M-1 battery cells other than the mth battery cell in the battery cluster, wherein the mth battery cell serves as a short-circuit fault battery, and the loop current equation is constructed based on the topological parameters of the energy storage system in which the battery cluster is located, m is a positive integer and 1<m<M; the predetermined voltage change threshold is determined based on the absolute value of the difference between the average voltage increase value of the M-1 battery cells and the voltage drop value of the mth battery cell.

[0011] According to an embodiment of the present invention, a loop current equation is used to obtain a voltage drop value of the mth battery cell in a battery cluster and an average voltage rise value of M-1 battery cells in the battery cluster except the mth battery cell, including: using the loop current equation to obtain a first branch current value of the branch where the mth battery cell is located and a second branch current value of the branch where the M-1 battery cells are located; obtaining an internal resistance value of the mth battery cell based on a terminal voltage change value and a terminal current change value of the mth battery cell when switching from a constant current charge / discharge state to a static state; obtaining an open circuit voltage value of the mth battery cell based on the internal resistance value of the mth battery cell and the terminal voltage value and terminal current value of the mth battery cell in a constant current charge / discharge state; obtaining a voltage drop value of the mth battery cell and an average voltage rise value of the M-1 battery cells based on the open circuit voltage value and the internal resistance value of the mth battery cell.

[0012] According to an embodiment of the present invention, a predetermined voltage change threshold is determined based on the absolute value of the difference between the average voltage increase value of M-1 battery cells and the voltage drop value of the m-th battery cell, including: obtaining an initial voltage change threshold based on the absolute value of the difference between the average voltage increase value of M-1 battery cells and the voltage drop value of the m-th battery cell; determining a braking coefficient based on at least one item of the charge status information, health status information and operating condition information of each of the M battery cells; and determining a predetermined voltage change threshold based on the initial voltage change threshold and the braking coefficient.

[0013] Another aspect of the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the method described above.

[0014] Another aspect of the present invention provides a computer-readable storage medium storing computer-executable instructions, which are used to implement the above method when executed.

[0015] Another aspect of the present invention provides a computer program product, comprising computer executable instructions, which are used to implement the method described above when the instructions are executed.

[0016] According to an embodiment of the present invention, the balanced state of an energy storage system indicates that a predetermined voltage control strategy is used to control the voltage of the M battery cells in a battery cluster, thereby reducing the differences in voltage or capacity between the individual battery cells in the battery cluster. Therefore, even when the battery cluster is in a balanced state, the voltage of some battery cells may drop while the voltage of others may increase due to control. Therefore, performing fault detection when the battery cluster is in a balanced state may result in a misjudgment of the fault state. Therefore, performing fault detection on the battery cluster when the battery cluster is not in a balanced state where the voltage of the battery cluster is controlled using the predetermined voltage control strategy reduces misjudgments of faults and improves the accuracy of fault detection. If, within a target time period, the voltage change value of at least one cascaded battery cell in the battery cluster is less than zero, and the voltage change values ​​of the remaining battery cells are all greater than zero, this indicates that the voltage change direction of some battery cells in the battery cluster is opposite to that of other battery cells. Since a battery cluster fault may also cause the voltage change direction of some battery cells to be opposite to that of other battery cells, performing subsequent judgments when the above conditions are met further improves the accuracy of fault detection. When the above conditions are met, a first statistical voltage change value and a second statistical voltage change value are determined, and a detection result is obtained based on the difference between the second statistical voltage change value and the first statistical voltage change value and a predetermined threshold value to determine whether the battery cluster is in a faulty state or a normal state. In this way, fault detection is performed by collaboratively considering the voltage changes of multiple battery cells in the battery cluster within the target time period, thereby reducing misjudgment or missed fault judgment and improving the accuracy of fault detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0018] Figure 1 A flow chart of a faulty battery detection method according to an embodiment of the present invention is shown;

[0019] Figure 2 A circuit diagram of a battery cluster having a local short circuit fault according to an embodiment of the present invention is shown;

[0020] Figure 3 Shown Figure 2 Schematic diagram of voltage changes of different battery cells in the circuit schematic shown;

[0021] Figure 4 Shown Figure 2 Equivalent circuit diagram of the circuit schematic shown;

[0022] Figure 5shows a schematic diagram of an equivalent model of a battery cell according to an embodiment of the present invention; and

[0023] Figure 6 A block diagram of an electronic device suitable for implementing a faulty battery detection method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When expressions such as "at least one of A, B, and C, etc." are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] Renewable energy is currently being integrated into power systems on a large scale. However, the high randomness and weak disturbance resistance of renewable energy generation can easily lead to voltage instability and frequency fluctuations in power systems. Lithium batteries can serve as the energy carrier for electrochemical energy storage systems. Against this backdrop, energy storage systems are limited by technical bottlenecks in their protection strategies, hindering their further development.

[0029] Currently, short-circuit protection devices on the DC side of energy storage power stations use fuses. However, fuses provide protection within a predetermined fault current range and are unable to cope with changes in fault current under complex operating conditions. Furthermore, after the fuse operates, the battery management system (BMS) struggles to accurately locate the fault, resulting in delayed fault isolation and even cascading failures, which can cause the fault to spread further.

[0030] In view of this, an embodiment of the present invention provides a faulty battery detection method, comprising: in response to M battery cells in a battery cluster not being in a balanced state, obtaining voltage change values ​​of each of the M battery cells within a target time period, wherein the target time period is determined based on a single voltage sampling cycle, the balanced state indicates voltage regulation of the battery cluster using a predetermined voltage regulation strategy, and M is a positive integer; in response to N cascaded battery cells in the battery cluster having voltage change values ​​each less than zero, and MN battery cells in the battery cluster having voltage change values ​​each greater than zero, obtaining a first statistical voltage change value based on the voltage change values ​​of the N battery cells and obtaining a second statistical voltage change value based on the voltage change values ​​of the MN battery cells, wherein N<M and N is a positive integer; and obtaining a detection result indicating whether the battery cluster is in a faulty state or a normal state based on a predetermined voltage change threshold and the difference between the first statistical voltage change value and the second statistical voltage change value.

[0031] Figure 1 A flow chart of a faulty battery detection method according to an embodiment of the present invention is shown.

[0032] like Figure 1 As shown, the method 100 includes operations S110 to S130.

[0033] In operation S110 , in response to the M battery cells in the battery cluster not being in a balanced state, a voltage change value of each of the M battery cells within a target period is obtained, where M is a positive integer.

[0034] In operation S120, in response to the voltage change values ​​of the N cascaded battery cells in the battery cluster being less than zero and the voltage change values ​​of the MN battery cells in the battery cluster being greater than zero, a first statistical voltage change value is obtained based on the voltage change values ​​of the N battery cells and a second statistical voltage change value is obtained based on the voltage change values ​​of the MN battery cells.

[0035] In operation S130 , a detection result indicating whether the battery cluster is in a fault state or a normal state is obtained based on a difference between the second statistical voltage change value and the first statistical voltage change value and a predetermined voltage change threshold.

[0036] According to an embodiment of the present invention, the energy storage system includes multiple parallel battery clusters. Each battery cluster includes M cascaded battery cells. A balanced state means that the voltage of the M battery cells in the battery cluster is regulated using a predetermined voltage regulation strategy (e.g., active or passive) to reduce differences in voltage or capacity between the individual battery cells in the cluster. This means that even when the battery cluster is in a balanced state, the voltage of some battery cells may drop while the voltage of others increases, potentially leading to a false alarm.

[0037] Therefore, when the battery cluster is in a balanced state, the detection process of the faulty battery is not triggered until the balanced state of the battery cluster is completed. That is, when the M battery cells in the battery cluster are not in a balanced state, the voltage change values ​​of the M battery cells within the target time period are obtained. The target time period is determined based on a single sampling cycle.

[0038] According to an embodiment of the present invention, when there is no local short-circuited battery cell in the battery cluster, the voltage change trend of all battery cells in the same battery cluster is the same, which is either rising or falling. In order to analyze the voltage change of each battery cell in the battery cluster when there is a local short-circuited battery cell in the battery cluster, the following will be used to analyze the voltage change of each battery cell in the battery cluster. Figure 2 and Figure 3 Provide explanation.

[0039] Figure 2 A circuit diagram of a battery cluster having a local short circuit fault according to an embodiment of the present invention is shown.

[0040] like Figure 2 As shown, the energy storage system includes multiple parallel battery clusters, and the equivalent load resistance R L Connect multiple battery clusters in parallel. For the battery cluster 210, it includes multiple cascaded battery cells (such as the battery cell 211 shown in the figure). Connect the short-circuit resistor R s The battery pack 220 includes a plurality of cascaded battery cells, that is, a local short circuit fault occurs in the battery pack 220 in the current energy storage system.

[0041] Figure 3 Shown Figure 2 Schematic diagram of voltage changes of different battery cells in the circuit schematic shown.

[0042] like Figure 3As shown, the horizontal axis represents the number of battery cells in battery pack 220. The vertical axis represents the difference between the voltage before and after the short circuit. The voltage change direction of battery pack 220 before and after the short circuit is opposite to the voltage change direction of the other battery cells in the battery cluster where battery pack 220 is located. Therefore, the voltage change direction of the battery cell experiencing a short circuit is opposite to that of the other battery cells in the same battery cluster before and after the short circuit.

[0043] Therefore, if there are N cascaded battery cells in the battery cluster, and the voltage change values ​​of each of the N battery cells are less than zero, and the voltage change values ​​of each of the MN battery cells in the battery cluster are greater than zero, the N cascaded battery cells can be determined as the battery group to be determined, and a first statistical voltage change value can be obtained based on the voltage change values ​​of each of the N battery cells, and a second statistical voltage change value can be obtained based on the voltage change values ​​of each of the MN battery cells, where N<M and N is a positive integer.

[0044] According to an embodiment of the present invention, the first statistical voltage change value may represent the arithmetic mean or weighted average of the voltage change values ​​of N battery cells. Correspondingly, the second statistical voltage change value may represent the arithmetic mean or weighted average of the voltage change values ​​of MN battery cells. The difference between the second statistical voltage change value and the first statistical voltage change value is compared with a predetermined voltage change threshold to obtain a detection result indicating whether the battery cluster is in a faulty state or a normal state.

[0045] According to an embodiment of the present invention, the predetermined voltage change threshold represents the minimum value that the difference between the second statistical voltage change value and the first statistical voltage change value can reach when a local short circuit fault occurs in the current battery cluster. Figure 3 It can be seen that the smaller the number of short-circuited battery cells is, the smaller the difference between the second statistical voltage change value and the first statistical voltage change value is.

[0046] According to the embodiment of the present application, the balanced state of the energy storage system indicates that the voltage of the M battery cells in the battery cluster is regulated by the predetermined voltage regulation strategy, which is used to reduce the difference between the voltage or capacity of each battery cell in the battery cluster, so that in the case of the balanced state of the battery cluster, the phenomenon of the voltage drop of some battery cells and the voltage rise of another part of the battery cells caused by regulation will occur, and if fault detection is performed in the case of the balanced state of the battery cluster, the fault state will be misjudged. Therefore, in the case that the battery cluster is not in the balanced state regulated by the predetermined voltage regulation strategy, the fault detection of the battery cluster is performed, which reduces the fault misjudgment and improves the accuracy of fault detection. If the voltage change value of at least one cascaded battery cell in the battery cluster in the target period is less than zero and the voltage change value of the remaining battery cells is greater than zero, it can be indicated that the voltage change direction of some battery cells in the battery cluster is opposite to that of another part of the battery cells, and since the voltage change direction of some battery cells may be opposite to that of another part of the battery cells in the case of a fault of the battery cluster, subsequent judgment is performed in the case of meeting the above condition, which further improves the accuracy of fault detection. In the case of meeting the above condition, the first statistical voltage change value and the second statistical voltage change value are determined, and a detection result is obtained according to the difference between the second statistical voltage change value and the first statistical voltage change value and a predetermined threshold value, to determine whether the battery cluster is in a fault state or a normal state. Therefore, the fault detection is performed by considering the voltage change of each battery cell in the battery cluster in the target period, which reduces the fault misjudgment or fault omission and improves the accuracy of fault detection.

[0047] According to the embodiment of the present application, the starting time of the target period is the time corresponding to the sum of the current sampling time and the preset delay, and the ending time of the target period is the last sampling time of the current sampling time; or the starting time of the target period is the current sampling time, and the ending time of the target period is the last sampling time of the current sampling time; wherein the voltage change value of each of the M battery cells in the target period is obtained by: for any battery cell in the M battery cells, obtaining a first voltage value of the battery cell at the starting time and a second voltage value of the battery cell at the ending time; and obtaining the voltage change value of the battery cell according to the first voltage value and the second voltage value.

[0048] The voltage change value of the mth battery cell in the battery cluster may be represented as formula (1) as follows.

[0049] (1).

[0050] Where t represents the current sampling time, τ represents the preset delay, Represents a single sampling period, represents the first voltage value of the mth battery cell when the starting time is the time corresponding to the sum of the current sampling time and the preset delay time, A second voltage value representing the voltage of the m-th battery cell.

[0051] According to an embodiment of the present invention, for the real-time voltage measurement of the BMS, it is possible that the voltage of the battery cell has changed but the BMS has not sensed it in time, resulting in a hysteresis in the voltage measurement. Therefore, a preset delay can be used to compensate for the voltage measurement error caused by this hysteresis. The preset delay can be greater than a single voltage sampling period, that is, τ> .

[0052] Taking the starting time of the target period as the current sampling time and the ending time of the target period as the previous sampling time as an example, the voltage change value of the mth battery cell in the battery cluster is It can also be expressed as the following formula (2).

[0053] (2).

[0054] in, Indicates the first voltage value of the voltage of the mth battery cell when the starting time is the current sampling time.

[0055] According to an embodiment of the present invention, a preset delay is introduced based on two adjacent sampling moments, and the starting moment of the target period is set to the moment corresponding to the sum of the current sampling moment and the preset delay, and the ending moment of the target period is set to the sampling moment before the current sampling moment, so that for any battery cell in the battery cluster, a first voltage value of the battery cell at the starting moment and a second voltage value at the ending moment are obtained; based on the first voltage value and the second voltage value, a voltage change value of the battery cell is obtained, so that fault detection is performed based on the voltage change values ​​of each of the M battery cells in the battery cluster, achieving a fault response speed of milliseconds, and accurately identifying fault states with smaller voltage drops, thereby reducing misjudgments and missed judgments of fault states.

[0056] According to an embodiment of the present invention, a detection result indicating whether a battery cluster is in a faulty state or a normal state is obtained based on the difference between the second statistical voltage change value and the first statistical voltage change value and a predetermined voltage change threshold value, including: obtaining a detection result indicating that the battery cluster is in a faulty state when the absolute value of the difference is greater than or equal to the predetermined voltage change threshold value; and obtaining a detection result indicating that the battery cluster is in a normal state when the absolute value of the difference is less than the predetermined voltage change threshold value.

[0057] According to an embodiment of the present invention, there are N cascaded battery cells in the battery cluster, and the voltage change value of each of them is less than zero, that is, ,in, It represents the voltage change value of the n1th battery cell in the N cascaded battery cells and the voltage change values ​​of the remaining MN battery cells in the battery cluster where the N cascaded battery cells are located are all greater than zero, that is, ,in, The voltage change value of the n2th battery cell among the MN battery cells is represented, and a first statistical voltage change value and a second statistical voltage change value are calculated.

[0058] According to an embodiment of the present invention, the first statistical voltage change value is the average value of the voltage change values ​​of N cascaded battery cells, which can be expressed as the following formula (3).

[0059] (3).

[0060] According to an embodiment of the present invention, the second statistical voltage change value is the average value of the voltage change values ​​of MN battery cells, which can be expressed as the following formula (4).

[0061] (4).

[0062] According to an embodiment of the present invention, the absolute value of the difference between the second statistical voltage change value and the first statistical voltage change value is greater than or equal to the predetermined voltage change threshold value. In the case of , a detection result indicating that the battery cluster is in a fault state is obtained. On the contrary, the absolute value of the difference between the second statistical voltage change value and the first statistical voltage change value is less than the predetermined voltage change threshold value. In the case of < , obtaining a detection result indicating that the battery cluster is in a normal state.

[0063] According to an embodiment of the present invention, in response to obtaining a detection result indicating that the battery cluster is in a fault state, it is determined that the N cascaded battery cells are short-circuit fault batteries.

[0064] According to an embodiment of the present invention, the absolute value of the difference between the second statistical voltage change value and the first statistical voltage change value is greater than or equal to the predetermined voltage change threshold value. In the case of N battery cells with voltage change values ​​less than zero, the N battery cells are determined to be short-circuit fault batteries, thereby realizing fault location.

[0065] According to an embodiment of the present invention, after obtaining a detection result indicating that a battery cluster is in a faulty state, N cascaded battery cells are identified as short-circuit fault batteries, and the detection result is uploaded to trigger a protection mechanism to cut off the branch where the short-circuit fault battery is located. This collaboratively considers the voltage variation patterns of multiple battery cells in the same battery cluster, thereby achieving accurate detection and positioning of short-circuit fault batteries.

[0066] According to an embodiment of the present invention, the predetermined voltage change threshold is determined according to the following operations: using a loop current equation, obtaining a voltage drop value of the mth battery cell in the battery cluster and an average voltage increase value of the M-1 battery cells in the battery cluster excluding the mth battery cell; and determining the predetermined voltage change threshold according to the absolute value of the difference between the average voltage increase value of the M-1 battery cells and the voltage drop value of the mth battery cell. Where m is a positive integer and 1<m<M.

[0067] Combined with the above Figure 3 It can be seen that when the number of short-circuit faulty cells is minimized, the difference between the voltage change values ​​of the battery cells that have not experienced short-circuit faults and the voltage change values ​​of the battery cells that have experienced short-circuit faults is minimized. Therefore, any battery cell can be selected as the short-circuit faulty cell. The predetermined voltage change threshold can be determined based on the absolute value of the difference between the average voltage increase of other battery cells in the same battery cluster and the voltage decrease of the current battery cell. The voltage decrease value of the mth battery cell represents the voltage change value of the mth battery cell before and after the short-circuit fault occurs, and the average voltage increase value of the M-1 battery cells represents the average voltage change value of each of the M-1 battery cells before and after the fault occurs.

[0068] The following will be Figure 2 Taking the circuit schematic diagram shown as an example, the loop current equation is explained.

[0069] Figure 4 Shown Figure 2 Equivalent circuit diagram of the circuit schematic shown.

[0070] like Figure 4 As shown, due to Figure 4 and Figure 2 Correspondingly, equivalent branch represents the equivalent branches of multiple battery clusters in the energy storage system except the battery cluster where the short-circuit fault battery is located, where U F1 Represents an equivalent branch The equivalent voltage source of all corresponding battery cells, R F1 Represents an equivalent branch The equivalent resistance of all corresponding battery cells. represents the equivalent branch where the battery pack 220 is located, where U F3 Represents an equivalent branch The equivalent voltage source of all corresponding battery cells, R F3 Represents an equivalent branch The equivalent resistance of all corresponding battery cells. Represents an equivalent branch Equivalent branch in the battery cluster The equivalent branch corresponding to all battery cells on the left, U F2 Represents an equivalent branch The equivalent voltage source of all corresponding battery cells, R F2 Represents an equivalent branch The equivalent resistance of all corresponding battery cells. Represents an equivalent branch Equivalent branch in the battery cluster The equivalent branches corresponding to all battery cells on the right, U F4 Represents an equivalent branch The equivalent voltage source of all corresponding battery cells, R F4 Represents an equivalent branch The equivalent resistance of all corresponding battery cells. I1, I2, and I3 represent the currents in the loops indicated by the arrows.

[0071] According to an embodiment of the present invention, the loop current equation is constructed based on the topological parameters of the energy storage system in which the battery cluster is located, and can be expressed as the following formula (5).

[0072] (5).

[0073] Among them, B b represents the loop matrix, T represents the matrix transpose symbol, Z b represents the impedance matrix, U bs represents the voltage source matrix, I b represents the current matrix, and B b 、Z b , I b 、U bs They satisfy the following equations (6) to (9) respectively.

[0074] (6).

[0075] (7).

[0076] (8).

[0077] (9).

[0078] in, Indicates the short-circuit resistance, Represents the equivalent load resistance.

[0079] According to an embodiment of the present invention, an energy storage system includes A battery clusters. Taking as an example that each battery cluster includes M battery cells, and the i-th battery cell in the battery cluster is the first battery cell in the battery cluster to suffer a short-circuit fault, the total number of battery cells suffering from the short-circuit fault is N, the internal resistance of each battery cell is R0, the open-circuit voltage is U0, and before the short-circuit fault occurs, the constant discharge current of each battery cell is I.

[0080] Equivalent branch The equivalent voltage source and equivalent resistance It can be expressed as the following formula (10).

[0081] (10).

[0082] Equivalent branch The equivalent voltage source and equivalent resistance It can be expressed as the following formula (11).

[0083] (11).

[0084] Equivalent branch The equivalent voltage source and equivalent resistance It can be expressed as the following formula (12).

[0085] (12).

[0086] Equivalent branch The equivalent voltage source and equivalent resistance It can be expressed as the following formula (13).

[0087] (13).

[0088] Equivalent load resistance .

[0089] According to the embodiment of the present invention, by combining the above formulas (5) to (13), the equivalent branch can be obtained: Current , equivalent branch Current , equivalent branch Current , equivalent branch Current .

[0090] According to an embodiment of the present invention, based on a loop current equation adapted to the topological parameters of the energy storage system, the absolute value of the difference between the average voltage increase of the remaining cells in the battery cluster and the voltage drop of the short-circuited cell is used as the predetermined voltage change threshold when a single cell short-circuit occurs. This achieves adaptive determination of the predetermined voltage change threshold. Based on this, the predetermined voltage change threshold is used to determine whether the battery cluster is in a faulty or normal state, improving the accuracy of faulty cell detection.

[0091] According to an embodiment of the present invention, a loop current equation is used to obtain a voltage drop value of the mth battery cell in a battery cluster and an average voltage rise value of M-1 battery cells in the battery cluster except the mth battery cell, including: using the loop current equation to obtain a first branch current value of the branch where the mth battery cell is located and a second branch current value of the branch where the M-1 battery cells are located; obtaining an internal resistance value of the mth battery cell based on a terminal voltage change value and a terminal current change value of the mth battery cell when switching from a constant current charge / discharge state to a static state; obtaining an open circuit voltage value of the mth battery cell based on the internal resistance value of the mth battery cell and the terminal voltage value and terminal current value of the mth battery cell in a constant current charge / discharge state; obtaining a voltage drop value of the mth battery cell and an average voltage rise value of the M-1 battery cells based on the open circuit voltage value and the internal resistance value of the mth battery cell.

[0092] Take N=1, and we can use the above equation based on the loop current to get , get the branch where the mth battery cell is located (i.e. equivalent branch ) of the first branch current value, and using the above and , get the branch where M-1 battery cells are located (i.e. equivalent branch and equivalent branches ) of the second branch current value.

[0093] According to an embodiment of the present invention, the voltage change value of any battery cell in the M-1 battery cells before and after the short circuit fault occurs is It can be expressed as the following formula (14).

[0094] (14).

[0095] By traversing and calculating the voltage change values ​​of each of the M-1 battery cells, the average voltage rise value of the M-1 battery cells can be obtained.

[0096] According to an embodiment of the present invention, the voltage change value of the mth battery cell before and after the short circuit fault occurs, that is, the voltage drop value It can be expressed as the following formula (15).

[0097] (15).

[0098] It can be seen that the above formulas (14) and (15) are related to the open circuit voltage and internal resistance of the battery cell. However, it has been found that the internal resistance and open circuit voltage of the battery cell change with the state of charge (SOC) and health (SOH) of the battery cell. In order to further improve the accuracy of the voltage change threshold, the following can be used Figure 5 Construct an equivalent model of the mth battery cell and calculate the internal resistance and open circuit voltage of the battery cell in real time.

[0099] Figure 5 FIG. 4 shows a schematic diagram of an equivalent model of a battery cell according to an embodiment of the present invention.

[0100] like Figure 5 As shown, the battery cell can be equivalent to a voltage source connected in series with an internal resistor. , Indicates the terminal voltage of the battery cell under constant current charge / discharge state. Indicates the current flowing through the battery cell, that is, the terminal current of the battery cell in the constant current charge / discharge state. When the internal resistance changes The voltage will also change, so the resistance of the internal resistance can be calculated according to the following formula (16).

[0101] (16).

[0102] Among them, for the energy storage system that maintains constant current charge / discharge state, there is no current change in the battery cell. When the battery cell switches from constant current charge / discharge state to static state, there is a terminal voltage change value. and terminal current change value .

[0103] According to an embodiment of the present invention, the above formula (16) can be substituted into the following formula (17) to obtain the open circuit voltage value.

[0104] (17).

[0105] Therefore, the current internal resistance and open circuit voltage of the battery cell can be calculated in real time according to formula (16) and formula (17), and the average voltage rise value of M-1 battery cells and the voltage drop value of the mth battery cell can be calculated respectively according to the above formulas (14) and (15).

[0106] According to an embodiment of the present invention, the voltage change threshold is determined using the loop current equation, making the fault status determination method applicable to a variety of energy storage systems, improving compatibility and universality. At the same time, considering that the internal resistance and open-circuit voltage of the battery cell change with SOC and SOH, the change in the terminal voltage and terminal current when the battery cell switches from the constant current charge / discharge state to the static state is used to obtain the current real-time internal resistance and open-circuit voltage of the battery cell, and then adjust the voltage change threshold in real time. This takes into account the impact of the changes in the battery cell's SOC and SOH with factors such as battery life on the internal resistance and open-circuit voltage of the battery cell, further improving the accuracy of fault battery detection.

[0107] According to an embodiment of the present invention, in addition to determining the state of the battery cluster based on the adaptive predetermined voltage change threshold and the difference between the second statistical voltage change value and the first statistical voltage change value, a coefficient may be introduced to further improve the accuracy of the detection result.

[0108] According to an embodiment of the present invention, a predetermined voltage change threshold is determined based on the absolute value of the difference between the average voltage increase value of M-1 battery cells and the voltage drop value of the m-th battery cell, including: obtaining an initial voltage change threshold based on the absolute value of the difference between the average voltage increase value of M-1 battery cells and the voltage drop value of the m-th battery cell; determining a braking coefficient based on at least one item of the charge status information, health status information and operating condition information of each of the M battery cells; and determining a predetermined voltage change threshold based on the initial voltage change threshold and the braking coefficient.

[0109] According to an embodiment of the present invention, the braking coefficient can be obtained by studying the historical data of multiple battery cells, summarizing the mapping relationship between the historical data and the braking coefficient, and then determining the current braking coefficient from the mapping relationship through a mapping table lookup method. The braking coefficient can take a value of 0.85~0.95.

[0110] The historical data includes at least one of historical state of charge information, historical health status information, and historical operating condition information.

[0111] According to an embodiment of the present invention, the initial voltage change threshold is adjusted according to the braking coefficient to obtain a predetermined voltage change threshold, which takes into account the influence of the charge state information, health status information and operating condition information of the battery cell on the relevant parameters of the battery cell, fills the gap in fault detection under extreme working conditions or complex working conditions, and further improves the accuracy of fault detection in various application scenarios.

[0112] Figure 6 A block diagram of an electronic device suitable for implementing a faulty battery detection method according to an embodiment of the present invention is shown. Figure 6The electronic device shown is only an example and should not limit the functions and scope of use of the embodiments of the present invention.

[0113] like Figure 6 As shown, an electronic device 600 according to an embodiment of the present invention includes a processor 601, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 602 or a program loaded from a storage unit 608 into a random access memory (RAM) 603. The processor 601 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 601 may also include onboard memory for caching purposes. The processor 601 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present invention.

[0114] Various programs and data required for the operation of the electronic device 600 are stored in the RAM 603. The processor 601, ROM 602, and RAM 603 are connected to each other via a bus 604. The processor 601 executes the programs in the ROM 602 and / or RAM 603 to perform various operations according to the method flow of the embodiment of the present invention. It should be noted that the programs may also be stored in one or more memories other than the ROM 602 and RAM 603. The processor 601 may also execute the programs stored in the one or more memories to perform various operations according to the method flow of the embodiment of the present invention.

[0115] According to an embodiment of the present invention, electronic device 600 may further include an input / output (I / O) interface 605, which is also connected to bus 604. Electronic device 600 may also include one or more of the following components connected to I / O interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including devices such as a cathode ray tube (CRT), liquid crystal display (LCD), and speakers; a storage section 608 including a hard disk; and a communication section 609 including a network interface card such as a LAN card or modem. Communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to I / O interface 605 as needed. Removable media 611, such as a magnetic disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed in drive 610 as needed, so that computer programs read from the removable media can be installed into storage section 608 as needed.

[0116] According to an embodiment of the present invention, the method flow according to an embodiment of the present invention can be implemented as a computer software program. For example, an embodiment of the present invention includes a computer program product, which includes a computer program carried on a computer-readable storage medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 609, and / or installed from the removable medium 611. When the computer program is executed by the processor 601, the above-mentioned functions defined in the system of the embodiment of the present invention are executed. According to an embodiment of the present invention, the system, device, apparatus, module, unit, etc. described above can be implemented by a computer program module.

[0117] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments, or may exist independently and not incorporated into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of the present invention.

[0118] According to embodiments of the present invention, a computer-readable storage medium may be a non-volatile computer-readable storage medium. Examples include, but are not limited to, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0119] For example, according to an embodiment of the present invention, the computer-readable storage medium may include the ROM 602 and / or the RAM 603 described above and / or one or more memories other than the ROM 602 and the RAM 603 .

[0120] An embodiment of the present invention also includes a computer program product, which includes a computer program containing program code for executing the method provided by the embodiment of the present invention. When the computer program product is run on an electronic device, the program code is used to enable the electronic device to implement the faulty battery detection method provided by the embodiment of the present invention.

[0121] When the computer program is executed by the processor 601, the above functions defined in the system / device of the embodiment of the present invention are performed. According to the embodiment of the present invention, the above-described systems, devices, modules, units, etc. can be implemented by computer program modules.

[0122] In one embodiment, the computer program can be tangibly embodied in a non-transitory machine-readable storage medium. In another embodiment, the computer program can be tangibly embodied in a signal that can be downloaded and installed by a communication interface 609, and / or installed from a removable medium 611. The computer program can include program code that can be transmitted over a network, including, but not limited to, wireless, wired, or any suitable combination thereof, or any suitable combination of the foregoing. The computer program can be downloaded and installed by a communication interface 609, and / or installed from a removable medium 611.

[0123] According to an embodiment of the present application, program code that implements the application embodiments provided by the present application can be written in any combination of one or more programming languages, including a high-level procedural and / or object-oriented programming language, and / or an assembly / machine language. Program code can execute entirely on a user's computing device, partly on the user's device, as a stand-alone software package, partly on a remote computing device, or entirely on the remote computing device or server. In the latter scenario, the remote computing device can be connected to the user's computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computing device, such as through the Internet using an Internet Service Provider. In some embodiments, the application provides a program that can be used to implement the application on a remote computing device.

[0124] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of the systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram may represent a module, program segment, or portion of code, which contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the boxes may occur in an order different from that marked in the accompanying drawings. For example, two boxes shown in succession may actually be executed substantially in parallel, or they may sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, as well as the combination of boxes in the block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or may be implemented using a combination of dedicated hardware and computer instructions. It will be understood by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or coupled in various ways, even if such combinations or couplings are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention may be combined and / or coupled in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0125] The above describes embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A method for detecting a faulty battery, characterized in that: include: In response to M battery cells in the battery cluster not being in a balanced state, obtaining voltage change values ​​of each of the M battery cells within a target period, wherein the target period is determined based on a single voltage sampling cycle, the balanced state indicates that voltage control of the battery cluster is performed using a predetermined voltage control strategy, and M is a positive integer; In response to the voltage change values ​​of N cascaded battery cells in the battery cluster being less than zero, and the voltage change values ​​of MN battery cells in the battery cluster being greater than zero, obtaining a first statistical voltage change value based on the voltage change values ​​of the N battery cells and obtaining a second statistical voltage change value based on the voltage change values ​​of the MN battery cells, where N<M and N is a positive integer; A detection result indicating whether the battery cluster is in a fault state or a normal state is obtained according to a difference between the second statistical voltage change value and the first statistical voltage change value and a predetermined voltage change threshold.

2. The method according to claim 1, characterized in that The starting time of the target period is the time corresponding to the sum of the current sampling time and the preset delay, and the ending time of the target period is the sampling time before the current sampling time; or the starting time of the target period is the current sampling time, and the ending time of the target period is the sampling time before the current sampling time; The step of obtaining the voltage change value of each of the M battery cells within the target time period includes: For any battery cell among the M battery cells, Obtaining a first voltage value of the battery cell at the starting time and a second voltage value at the ending time; A voltage change value of the battery cell is obtained according to the first voltage value and the second voltage value.

3. The method according to claim 2, characterized in that The preset delay is greater than the single voltage sampling period.

4. The method according to any one of claims 1 to 3, characterized in that The first statistical voltage change value is an average of the voltage change values ​​of the N cascaded battery cells, and the second statistical voltage change value is an average of the voltage change values ​​of the MN battery cells; The step of obtaining a detection result indicating whether the battery cluster is in a fault state or a normal state based on a difference between the second statistical voltage change value and the first statistical voltage change value and a predetermined voltage change threshold value includes: When the absolute value of the difference is greater than or equal to the predetermined voltage change threshold, obtaining a detection result indicating that the battery cluster is in a fault state; When the absolute value of the difference is smaller than the predetermined voltage change threshold, a detection result indicating that the battery cluster is in a normal state is obtained.

5. The method according to claim 4, characterized in that The method further comprises: In response to obtaining a detection result indicating that the battery cluster is in a fault state, it is determined that the N cascaded battery cells are short-circuit fault batteries.

6. The method according to any one of claims 1 to 3, characterized in that The predetermined voltage change threshold is determined according to the following operations: Using a loop current equation, a voltage drop value of the mth battery cell in the battery cluster and an average voltage increase value of M-1 battery cells in the battery cluster other than the mth battery cell are obtained, wherein the mth battery cell serves as a short-circuit fault battery, and the loop current equation is constructed based on topological parameters of the energy storage system in which the battery cluster is located, where m is a positive integer and 1<m<M; The predetermined voltage change threshold is determined according to an absolute value of a difference between an average voltage increase value of the M-1 battery cells and a voltage decrease value of the m-th battery cell.

7. The method according to claim 6, characterized in that The method of using the loop current equation to obtain the voltage drop value of the mth battery cell in the battery cluster and the average voltage increase value of M-1 battery cells in the battery cluster excluding the mth battery cell includes: Using the loop current equation, obtain a first branch current value of the branch where the m-th battery cell is located and a second branch current value of the branch where the M-1 battery cell is located; Obtaining an internal resistance value of the mth battery cell according to a terminal voltage change value and a terminal current change value of the mth battery cell when the mth battery cell is switched from a constant current charge / discharge state to a static state; Obtaining an open circuit voltage value of the mth battery cell according to the internal resistance value of the mth battery cell and the terminal voltage value and terminal current value of the mth battery cell in the constant current charge / discharge state; According to the open circuit voltage value and the internal resistance value of the m-th battery cell, the voltage drop value of the m-th battery cell and the average voltage increase value of the M-1 battery cells are obtained.

8. The method according to claim 6, characterized in that The determining the predetermined voltage change threshold according to the absolute value of the difference between the average voltage increase value of the M-1 battery cells and the voltage drop value of the m-th battery cell includes: Obtaining an initial voltage change threshold value according to an absolute value of a difference between an average voltage increase value of the M-1 battery cells and a voltage drop value of the m-th battery cell; determining a braking coefficient according to at least one of state of charge information, health status information, and operating condition information of each of the M battery cells; The predetermined voltage change threshold is determined according to the initial voltage change threshold and the braking coefficient.

9. An electronic device, characterized in that: include: one or more processors; a memory for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 8.

10. A computer-readable storage medium having executable instructions stored thereon, characterized in that: When the instruction is executed by a processor, the processor implements the method according to any one of claims 1 to 8.

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