Balanced control method and device for energy storage system

Abstract

The invention provides a balance control method and device of an energy storage system, the energy storage system comprises a plurality of battery clusters, and each battery cluster is connected in series with a DC / DC module; the equalization control method comprises the following steps: determining a current distribution rule in a battery cluster of the energy storage system under various working conditions; determining a target battery cluster put into operation of the energy storage system under the target working condition, and obtaining an initial remaining power state of the target battery cluster; determining a target current distribution proportion of the target battery cluster based on a target current distribution rule corresponding to the target working condition and / or an initial remaining power state of the target battery cluster; according to the target current distribution proportion, the current in the target battery cluster is controlled, so that the electric quantity state of the energy storage system changes in a balanced mode, all the target battery clusters soc of the system change in a balanced mode, all the clusters soc are consistent after the system enters the standing working condition, the difference of the sum of ocv of all the clusters of battery cells is reduced, and inter-cluster circulation is avoided based on a DC / DC module.

Description

Technical Field

[0001] The present application relates to the field of battery management technology, and in particular to a method and device for balancing control of an energy storage system. Background Art

[0002] Due to the heterogeneity of batteries and components, the traditional energy storage system has a large difference in the soc (state-of-charge) of each battery cluster. During the system's charging and discharging operation, the inconsistency of soc will lead to a large difference in the sum of the open-circuit voltages (OCV) of each battery in the battery cluster. In parallel operation, the current size of each cluster cannot be accurately controlled, resulting in an imbalance in the charging and discharging current. Long-term current differences directly lead to large temperature differences between clusters. At the same time, when the system is static, the difference in soc is reflected in the inconsistency of the sum of the open-circuit voltages (OCV) of each battery in the battery cluster, causing a large inter-cluster circulating current. The unbalanced current and inter-cluster circulating current further aggravate the inconsistency between clusters, forming a vicious circle, which ultimately affects the system performance and life. Summary of the invention

[0003] In view of this, the purpose of the present application is to provide a balancing control method and device for an energy storage system, which can dynamically adjust the voltage and current of each battery cluster through a DC / DC module, so that the current changes of each battery cluster under various working conditions meet the balancing requirements, reduce the difference in the sum of the OCVs of the battery cells in each cluster, and avoid inter-cluster circulation through the DC / DC module.

[0004] An embodiment of the present application provides a balanced control method for an energy storage system, wherein the energy storage system includes a plurality of battery clusters, each battery cluster being connected in series with a DC / DC module; the balanced control method includes:

[0005] Determine the current distribution rules in the battery cluster of the energy storage system under various working conditions; wherein the current distribution rules are used to determine the current distribution ratio of the battery cluster put into operation based on the initial remaining power state; different working conditions correspond to different current distribution rules; the working conditions include charging working conditions, discharging working conditions, and static working conditions;

[0006] Determine the target battery cluster that the energy storage system is put into operation under the target operating conditions, and obtain the initial remaining power state of the target battery cluster;

[0007] Determining a target current distribution ratio of the target battery cluster based on a target current distribution rule corresponding to the target operating condition and / or an initial remaining power state of the target battery cluster;

[0008] The current in the target battery cluster is controlled according to the target current distribution ratio, so that the charge states of different target battery clusters of the energy storage system under the target working condition change evenly.

[0009] In some embodiments, in the energy storage system balancing control method, based on the target current distribution rule corresponding to the target operating condition and / or the initial remaining power state of the target battery cluster, determining the target current distribution ratio of the target battery cluster includes:

[0010] When the target operating condition is a stationary condition, the current ratio is evenly distributed according to the number of target battery clusters.

[0011] In some embodiments, in the energy storage system balancing control method, based on the target current distribution rule corresponding to the target operating condition and / or the initial remaining power state of the target battery cluster, determining the target current distribution ratio of the target battery cluster includes:

[0012] When the target operating conditions are charging and discharging conditions, whether the energy storage system meets the preset balancing conditions is determined according to the initial remaining power state of the target battery cluster;

[0013] If it meets the requirement, the current ratio is evenly distributed according to the number of target battery clusters;

[0014] If not, the remaining power change capacity is determined according to the initial remaining power state and the target power state;

[0015] Based on the proportional relationship between the remaining power change capacities of different target battery clusters, the target current distribution ratio of the target battery cluster is determined.

[0016] In some embodiments, in the energy storage system balancing control method, judging whether the energy storage system meets the preset balancing condition according to the initial remaining power state of the target battery cluster includes:

[0017] Determining a balancing parameter of the energy storage system according to the initial remaining power state of the target battery cluster; wherein the balancing parameter is used to characterize the difference in initial remaining power of different target battery clusters;

[0018] It is determined whether the equalization parameter is less than a preset equalization threshold.

[0019] In some embodiments, in the energy storage system balancing control method, determining the balancing parameters of the energy storage system according to the initial remaining power of the target battery cluster includes:

[0020] Determine a maximum initial remaining power state and a minimum initial remaining power state of a target battery cluster of the energy storage system;

[0021] The difference between the maximum initial remaining power state and the minimum initial remaining power state is determined as a balancing parameter of the energy storage system.

[0022] In some embodiments, in the energy storage system balancing control method, the remaining power change capacity includes the remaining chargeable capacity under charging conditions and the remaining dischargeable capacity under discharging conditions;

[0023] Determine the remaining power change capacity according to the initial remaining power state and the target power state; including:

[0024] When the target operating condition is a discharge operating condition, the remaining dischargeable capacity when the remaining power state is 0 is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity;

[0025] When the target operating condition is a charging operating condition, the remaining chargeable capacity when charging to the remaining power state of 100% is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity;

[0026] The battery capacity upper limit represents the capacity upper limit of the battery cluster when operating in a target operating condition.

[0027] In some embodiments, in the energy storage system balancing control method, determining the remaining dischargeable capacity when the remaining power state is 0 according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity includes:

[0028] Determine the product of the initial remaining power state of the target battery cluster and the upper limit of the battery capacity as the remaining discharge capacity;

[0029] According to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity, the remaining chargeable capacity when charging to the remaining power state of 100% is determined, including:

[0030] Determine a difference percentage between an initial state of charge remaining of the target battery cluster and a state of charge remaining of 100%;

[0031] The product of the difference percentage of the target battery cluster and the upper limit of the battery capacity is determined as the remaining chargeable capacity.

[0032] In some embodiments, in the energy storage system balancing control method, based on the proportional relationship between the remaining power change capacities of different target battery clusters, the target current distribution ratio of the target battery cluster is determined, including:

[0033] Calculate the sum of the remaining power change capacity of all target battery clusters;

[0034] Calculate the ratio of the remaining power change capacity of each target battery cluster to the sum of the remaining power change capacities;

[0035] The ratio of each target battery cluster is determined as the target current distribution ratio of the target battery cluster.

[0036] In some embodiments, in the energy storage system balancing control method, controlling the current in the target battery cluster according to the target current distribution ratio includes:

[0037] The output current of the DC / DC modules connected in series to the target battery cluster is controlled and distributed according to the target current distribution ratio, so as to control the current size in the target battery cluster.

[0038] In some embodiments, in the energy storage system balancing control method, controlling the current in the target battery cluster according to the target current distribution ratio includes:

[0039] Based on the pre-calculated and real-time remaining power change capacity of the target battery cluster, determine the battery cluster with the largest remaining power change capacity as the master control node;

[0040] Controlling and distributing the current of each target battery cluster in series according to the target current distribution ratio;

[0041] Based on the sum of the currents of the target battery clusters other than the master control node, the current in the battery cluster serving as the master control node is adjusted so that the sum of the currents of all the target battery clusters is equal to the bus current of the energy storage system.

[0042] In some embodiments, the energy storage system balancing control method further includes:

[0043] When it is detected that a preset update condition is met, updating the target current distribution ratio;

[0044] updating the current size in the target battery cluster according to the updated target current distribution ratio;

[0045] The preset update conditions include: the target operating condition of the energy storage system changes, the target battery cluster put into operation changes, and the energy storage system is updated according to the preset collection frequency.

[0046] In some embodiments, in the energy storage system balancing control method, determining the current distribution rules in the battery cluster of the energy storage system under various working conditions includes:

[0047] Determine the equivalent model of the DC / DC module connected in series with the target battery cluster in the energy storage system; wherein; when the relay of the target battery cluster is opened, the DC / DC module connected in series with the target battery cluster is equivalent to a series controlled voltage source; when the relay of the target battery cluster is closed, the DC / DC module connected in series with the target battery cluster is equivalent to a series controlled current source;

[0048] Based on the equivalent model of DC / DC module, the energy storage system model is constructed;

[0049] Based on the constructed energy storage system model, the process of voltage regulation of the target battery cluster within the preset voltage regulation range through the DC / DC module is simulated by a series controlled voltage source. The process of operation of the target battery cluster according to the current distribution ratio through the DC / DC module is simulated by a series controlled current source. The current distribution rules in the battery cluster of the energy storage system under various working conditions are determined.

[0050] In some embodiments, in the energy storage system balancing control method, the equivalent model of the DC / DC module of the target battery cluster in the energy storage system in series includes: a relay, a series controlled voltage source, a series controlled current source, and a switching circuit;

[0051] When the relay is opened, the switching circuit is driven to switch to a state where the voltage source is connected in series with the target battery cluster; when the relay is closed, the switching circuit is driven to switch to a state where the current source is connected in series with the target battery cluster.

[0052] In some embodiments, in the energy storage system balancing control method, the step of obtaining the initial remaining power state of the target battery cluster includes:

[0053] When the target operating condition is a charging operating condition, determining the maximum initial remaining power state of the cells in the battery cluster as the initial remaining power state of the target battery cluster;

[0054] When the target operating condition is a discharging operating condition, the minimum initial remaining power state of the cells in the battery cluster is determined as the initial remaining power state of the target battery cluster.

[0055] In some embodiments, a balancing control device for an energy storage system is further provided. The energy storage system includes a plurality of battery clusters, each battery cluster is connected in series with a DC / DC module; the balancing control device includes:

[0056] The first determination module is used to determine the current distribution rules in the battery cluster of the energy storage system under various working conditions; wherein the current distribution rules are used to determine the current distribution ratio of the battery cluster put into operation based on the initial remaining power state; different working conditions correspond to different current distribution rules; the working conditions include charging working conditions, discharging working conditions, and static working conditions;

[0057] An acquisition module is used to determine a target battery cluster that is put into operation under a target operating condition of the energy storage system, and to obtain an initial remaining power state of the target battery cluster;

[0058] A second determination module, configured to determine a target current distribution ratio of a target battery cluster based on a target current distribution rule corresponding to a target operating condition and / or an initial remaining power state of the target battery cluster;

[0059] The control module is used to control the current in the target battery cluster according to the target current distribution ratio, so that the power states of different target battery clusters of the energy storage system under the target working condition change evenly.

[0060] The embodiment of the present application provides a balanced control method and device for an energy storage system, wherein the energy storage system includes a plurality of battery clusters, each battery cluster being connected in series with a DC / DC module; the balanced control method includes: determining a current distribution rule in a battery cluster of the energy storage system under a plurality of operating conditions; wherein the current distribution rule is used to determine a current distribution ratio of a battery cluster put into operation based on an initial remaining power state; different operating conditions correspond to different current distribution rules; the operating conditions include a charging operating condition, a discharging operating condition, and a static operating condition; determining a target battery cluster put into operation by the energy storage system under a target operating condition, and obtaining an initial remaining power state of the target battery cluster; determining a target current distribution rule corresponding to the target operating condition, and / or an initial remaining power state of the target battery cluster; determining a target current distribution rule corresponding to the target operating condition, and / or an initial remaining power state of the target battery cluster; determining a target current distribution rule corresponding to the target operating condition, and / or an initial remaining power state of the target battery cluster; determining a target current distribution rule corresponding to the target operating condition, and / or an initial remaining power state of the target battery cluster; determining a target current distribution ratio of a battery cluster put into operation based on the ... The target current distribution ratio of the target battery cluster is determined according to the remaining power state; the current size in the target battery cluster is controlled according to the target current distribution ratio, so that the power state of different target battery clusters of the energy storage system under the target working condition changes evenly; in this way, by providing the current distribution ratio to the battery cluster put into operation, the current in the target battery cluster with the initial remaining power state changes according to the current distribution ratio, so that the soc of each target battery cluster of the system reaches 100% at the same time in a charging condition or reaches 0% at the same time in a discharging condition, and the soc of each cluster is consistent during operation and after entering the static condition, so as to reduce the difference in the sum of the ocv of the cells of each cluster, and avoid the circulation current between clusters through the DC / DC module. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0062] Figure 1 A flow chart showing a balanced control method for an energy storage system according to an embodiment of the present application is shown;

[0063] Figure 2 A flow chart of a method for determining current distribution rules in a battery cluster of an energy storage system under various working conditions according to an embodiment of the present application is shown;

[0064] Figure 3 It shows the equivalent series controlled voltage source of the DC / DC modules connected in series before the relay of the battery cluster described in the embodiment of the present application is closed;

[0065] Figure 4 It shows the equivalent series controlled current source of the DC / DC module connected in series after the relay of the battery cluster described in the embodiment of the present application is closed;

[0066] Figure 5 The topology of the energy storage system model after the relay is closed according to the embodiment of the present application is shown;

[0067] Figure 6 The circuit topology structure of the equivalent model of the DC / DC module described in the embodiment of the present application is shown;

[0068] Figure 7 The circuit topology structure of the equivalent model of the DC / DC module described in the embodiment of the present application is shown;

[0069] Figure 8 The soc simulation results of the energy storage system model described in the embodiment of the present application are shown;

[0070] Fig. 9 A schematic structural diagram of a balancing control device for an energy storage system according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0071] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0072] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0073] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0074] Due to the heterogeneity of batteries and components, the traditional energy storage system has a large difference in the soc (state-of-charge) of each battery cluster. During the system's charging and discharging operation, the inconsistency of soc will lead to a large difference in the sum of the open-circuit voltages (OCV) of each battery in the battery cluster. In parallel operation, the current size of each cluster cannot be accurately controlled, resulting in an imbalance in the charging and discharging current. Long-term current differences directly lead to large temperature differences between clusters. At the same time, when the system is static, the difference in soc is reflected in the inconsistency of the sum of the open-circuit voltages (OCV) of each battery in the battery cluster, causing a large inter-cluster circulating current. The unbalanced current and inter-cluster circulating current further aggravate the inconsistency between clusters, forming a vicious circle, which ultimately affects the system performance and life.

[0075] Based on this, an embodiment of the present application provides a balanced control method and device for an energy storage system, wherein the energy storage system includes multiple battery clusters, each battery cluster is connected in series with a DC / DC module; the balanced control method includes: determining current distribution rules in the battery cluster of the energy storage system under multiple operating conditions; wherein the current distribution rules are used to determine the current distribution ratio of the battery cluster put into operation based on the initial remaining power state; different operating conditions correspond to different current distribution rules; the operating conditions include charging conditions, discharging conditions, and static conditions; determining a target battery cluster put into operation by the energy storage system under the target operating condition, and obtaining the initial remaining power state of the target battery cluster; based on the target current distribution rule corresponding to the target operating condition, and / or the initial remaining power state of the target battery cluster The target current distribution ratio of the target battery cluster is determined according to the initial remaining power state; the current size in the target battery cluster is controlled according to the target current distribution ratio, so that the power state of different target battery clusters of the energy storage system under the target working condition changes evenly; in this way, by providing the current distribution ratio to the battery cluster put into operation, the current in the target battery cluster with the initial remaining power state changes according to the current distribution ratio, so that the soc of each target battery cluster of the system reaches 100% at the same time in a charging condition or reaches 0% at the same time in a discharging condition, and the soc of each cluster is consistent during operation and after entering the static condition, so as to reduce the difference in the sum of the ocv of the battery cells of each cluster, and avoid the circulation current between clusters through the DC / DC module.

[0076] Please refer to Figure 1 , Figure 1 A flow chart of a balanced control method for an energy storage system according to an embodiment of the present application is shown, wherein the energy storage system comprises a plurality of battery clusters, each battery cluster being connected in series with a DC / DC module; the balanced control method comprises the following steps S101-S104:

[0077] S101, determining a current distribution rule in a battery cluster of an energy storage system under various operating conditions; wherein the current distribution rule is used to determine a current distribution ratio of a battery cluster put into operation based on an initial remaining power state; different operating conditions correspond to different current distribution rules; the operating conditions include a charging condition, a discharging condition, and a static condition;

[0078] S102, determining a target battery cluster that the energy storage system is put into operation under a target operating condition, and obtaining an initial remaining power state of the target battery cluster;

[0079] S103, determining a target current distribution ratio of the target battery cluster based on a target current distribution rule corresponding to the target operating condition and / or an initial remaining power state of the target battery cluster;

[0080] S104: Control the current in the target battery cluster according to the target current distribution ratio, so that the power states of different target battery clusters of the energy storage system under the target working condition change evenly.

[0081] In the embodiment of the present application, the balancing control method of the energy storage system is run in a terminal device or a host computer, and the terminal device can be a BMS system. BMS (Battery Management System), that is, a battery management system, is a device that cooperates to monitor the status of energy storage batteries. Its main purpose is to intelligently manage and maintain each battery unit to prevent overcharging and over-discharging of the battery, so as to extend the service life of the battery and monitor the status of the battery. BMS can monitor and collect the status parameters of the energy storage battery in real time, and perform necessary analysis and calculation on the relevant status parameters to obtain more system status evaluation parameters, and realize effective control of the energy storage battery body according to specific protection control strategies to ensure the safe and reliable operation of the entire battery energy storage unit.

[0082] Therefore, the BMS system can configure current distribution rules in the battery cluster under various operating conditions, determine the real-time operating conditions of the battery cluster, obtain the initial remaining power state of the battery cluster, the current capacity upper limit of the battery cluster, and so on.

[0083] The energy storage system described in the embodiment of the present application includes multiple battery clusters, each battery cluster is connected in series with a DC / DC module. The energy storage system of the series DC / DC modules improves the availability of the battery clusters compared to the traditional direct parallel solution of the battery clusters. The voltage of each cluster is dynamically adjusted by the DC / DC module to adapt to the DC bus voltage, so that the system efficiency is improved and the system DOD is increased. At the same time, compared with the energy storage system of the parallel DC / DC modules, the parallel DC / DC has much higher device withstand voltage requirements, power requirements and costs than the series DC / DC. Therefore, the series DC / DC has lower requirements on the withstand voltage level of components and lower costs. It only needs to consider the voltage drop across the battery positive electrode and the DC bus positive electrode voltage, and the current and voltage output can be accurately controlled within the rated power range.

[0084] In the step S101, current distribution rules in a battery cluster of an energy storage system under various operating conditions are determined; wherein the current distribution rules are used to determine the current distribution ratio of a battery cluster put into operation based on an initial remaining power state; different operating conditions correspond to different current distribution rules; the operating conditions include charging conditions, discharging conditions, and static conditions;

[0085] The current distribution rule may also be referred to as a current distribution algorithm, etc. The current distribution rule characterizes the law of balanced change of the state of charge of different battery clusters in the energy storage system. Therefore, according to the current distribution rule, the current of different battery clusters can be accurately controlled according to the law of balanced change of the state of charge.

[0086] In order to analyze and present the functional characteristics of the series DC / DC, determine the current distribution rules in the battery cluster of the energy storage system under various working conditions, that is, to determine the law of balanced change of the state of charge of different battery clusters, it is necessary to establish an energy storage system model (specifically a series battery cluster model in the embodiment of the present application) for system testing and research.

[0087] However, the energy storage system contains more battery cells and DC / DC modules, that is, it includes a large number of components and the components have complex connection relationships. Ordinary computers cannot simulate the battery system (step size of about 1s) and the DC / DC model involving high-speed power switching devices (step size ≤10us) at the same time, so it is difficult to establish an energy storage system model to study the law of balanced changes in the state of charge.

[0088] To solve this problem, the embodiment of the present application performs equivalent modeling on the series DC / DC model and reflects its external characteristics in the battery system model, thereby determining the current distribution rules in the battery cluster of the energy storage system under various working conditions.

[0089] Please refer to Figure 2 , determining the current distribution rules in the battery cluster of the energy storage system under various working conditions, including the following steps S201-S203:

[0090] S201, determining an equivalent model of a DC / DC module connected in series with a target battery cluster in an energy storage system; wherein: when the relay of the target battery cluster is open, the DC / DC module connected in series with the target battery cluster is equivalent to a series controlled voltage source; when the relay of the target battery cluster is closed, the DC / DC module connected in series with the target battery cluster is equivalent to a series controlled current source;

[0091] S202, constructing an energy storage system model based on an equivalent model of a DC / DC module;

[0092] S203. Based on the constructed energy storage system model, a series controlled voltage source is used to simulate the process of voltage regulation of the target battery cluster through the DC / DC module within a preset voltage regulation range. A series controlled current source is used to simulate the process of the target battery cluster operating according to the current distribution ratio through the DC / DC module, so as to determine the current distribution rules in the battery cluster of the energy storage system under various working conditions.

[0093] In order to simulate the current balance change law of the energy storage system, in the embodiment of the present application, when constructing a series DC / DC equivalent model (ie, an energy storage system model), the current and voltage need to be decoupled and controlled.

[0094] The control logic of the DC / DC module is as follows: when the main relay of the battery cluster is opened, the DC / DC module simulates no-load voltage regulation, and the DC / DC module is equivalent to a series controlled voltage source. As an example only, the input of the series controlled voltage source is 10V; when the main relay of the battery cluster is closed, the DC / DC module is equivalent to a series controlled current source, and the input of the series controlled current source is the true value of the current calculated based on the current distribution rule.

[0095] The bus voltage control logic is as follows: determine whether there is a battery cluster connected to the cabinet. If so, the DC bus controlled voltage source input is the minimum terminal voltage of the currently connected battery cluster +20V; if not, the DC bus controlled voltage source input is 0V.

[0096] Please refer to Figure 3 , Figure 3 The figure shows the equivalent series controlled voltage source of the series DC / DC module before the battery cluster relay is closed; when the battery cluster relay does not receive the high-voltage command, the relay is in the open state, and the DC / DC can only operate with no-load voltage regulation. Therefore, before the relay is closed, the DC / DC is equivalent to a series controlled voltage source U, which realizes the battery cluster voltage regulation within the range of 10 to 20V through the DC / DC.

[0097] Please refer to Figure 4 , Figure 4The figure shows the equivalent series controlled current source of the series DC / DC module after the battery cluster relay is closed; after the battery cluster relay receives the upper high voltage command and is closed, the equivalent DC / DC model only considers the branch current distribution, and a series controlled current source I is connected in series with the battery cluster branch. The true value of the series controlled current source I is obtained through the current distribution algorithm to simulate the charging and discharging process of the battery cluster, and to check whether the SOC of the battery cluster changes evenly under the control of the current distribution algorithm.

[0098] Please refer to Figure 5 , Figure 5 The topology of the energy storage system model after the relay is closed in the embodiment of the present application is shown. Since the internal resistance of the ideal controlled current source is infinite, the voltage across it is calculated based on the total resistance of the external circuit. Therefore, for the system voltage outer loop, it is considered to connect an ideal controlled voltage source V_bus in parallel on the DC bus side for voltage stabilization, and connect an ideal controlled current source I_bus in parallel on the DC bus side for total current excitation. Figure 5 In the three battery cluster branches shown, after the relay is closed, the DC / DC modules of the three battery clusters connected in series are equivalent to a series controlled current source I1, a series controlled current source I2, and a series controlled current source I3 respectively.

[0099] It can be seen that in the embodiment of the present application, the model equivalent to the DC / DC module changes with the action of the battery cluster relay. To conveniently implement this function, in the embodiment of the present application, the equivalent model of the DC / DC module of the target battery cluster in series in the energy storage system includes: a relay, a series controlled voltage source, a series controlled current source, and a switching circuit;

[0100] When the relay is opened, the switching circuit is driven to switch to a state where the voltage source is connected in series with the target battery cluster; when the relay is closed, the switching circuit is driven to switch to a state where the current source is connected in series with the target battery cluster.

[0101] The state of the voltage source being connected in series with the target battery cluster is that the series-controlled voltage source is connected in series with the target battery cluster and the series-controlled current source is short-circuited; the state of the current source being connected in series with the target battery cluster is that the series-controlled current source is connected in series with the target battery cluster and the series-controlled voltage source is short-circuited.

[0102] In this way, based on the characteristics that an ideal voltage source cannot be short-circuited and an ideal current source cannot be open-circuited, the circuit topology of the DC / DC module in the energy storage system model is realized.

[0103] For details, please refer to Figure 6 and Figure 7 , Figure 6 The circuit topology structure of the equivalent model of the DC / DC module described in the embodiment of the present application is shown; Figure 7 The circuit topology structure of the equivalent model of the DC / DC module described in the embodiment of the present application is shown; Figure 6The circuit topology in the DC / DC module is equivalent to a series controlled voltage source. Figure 7 The circuit topology in the embodiment is in a state where the DC / DC module is equivalent to a series controlled current source.

[0104] like Figure 6 and Figure 7 As shown, the switching circuit includes a single-pole double-throw switch SPTD and a first relay Ks1, a second relay Ks2, a third relay Ks3, and a fourth relay Ks4 linked with the battery cluster relay Ks; when the battery cluster relay Ks is opened, the first relay Ks1, the second relay Ks2, and the fourth relay Ks4 are closed, and the third relay Ks3 is opened; when the battery cluster relay Ks is closed, the first relay Ks1, the second relay Ks2 are opened, and the third relay Ks3 is closed.

[0105] The first end of the series controlled current source Ir is connected in series with the battery cluster relay Ks, the first fixed end of the single-pole double-throw switch SPTD is connected to the first end of the series controlled current source Ir, the moving end of the single-pole double-throw switch SPTD is connected in series with the second end of the controlled current source Ir, the second fixed end of the single-pole double-throw switch SPTD is connected in series with the controlled voltage source Ur through the third relay Ks3 and the second end of the fourth relay Ks4; the battery cluster relay Ks is connected in series with the first end of the controlled voltage source through the first relay Ks1 and the second relay Ks2.

[0106] Please refer to Figure 6 When the battery cluster relay Ks signal is 0, the battery cluster relay Ks is opened, the series controlled current source Ir is short-circuited through the single-pole double-throw switch SPTD, the third relay Ks3 is disconnected, and the first relay Ks1, the second relay Ks2, and the third relay Ks3 are closed, and the series controlled voltage source Ur is connected in series with the target battery cluster to form a voltage source series circuit; Clear reference Figure 7 When the battery cluster relay Ks signal is 1, the battery cluster relay Ks is closed, the series controlled current source Ir is connected to the main circuit via SPDT, the third relay Ks3 is closed, the first relay Ks1, the second relay Ks2, and the fourth relay Ks4 are disconnected, and the series controlled current source Ir is connected in series with the target battery cluster to form a current source series circuit.

[0107] Through the energy storage system model, the current distribution rules for each working condition are studied.

[0108] In the embodiment of the present application, in order to solve the problem of automatic current diversion based on the inconsistency of the traditional system according to the voltage difference and internal resistance, the current percentage should be accurately allocated to each cluster in proportion to ensure that the battery clusters of different capacities maintain the same SOC during operation. The current distribution rules are as follows:

[0109] Determine the current number of parallel clusters n, the initial remaining power state soc0 of each battery cluster, calculate the difference Δsoc0 between the maximum initial remaining power and the minimum initial remaining power as a balancing parameter, and determine whether Δsoc0 is less than a preset balancing threshold; illustratively, the preset balancing threshold is 0.5%, if so, calculate the output current distribution ratio according to the current number of parallel clusters n; as an example only, in the embodiment of the present application, the current distribution ratio is in the form of a percentage;

[0110] When the balancing parameter is less than the preset balancing threshold, the current distribution ratio is determined by the following formula (1):

[0111]

[0112] Among them, I i，pct Characterizes the current distribution ratio of battery cluster i; n represents the number of parallel clusters n, that is, the number of target battery clusters put into operation.

[0113] When the balancing parameter is greater than or equal to the preset balancing threshold, that is, if the maximum initial Δsoc0 is greater than or equal to 0.5%, under the discharge condition, the minimum soc of the cells in the cluster i is taken as soc i , according to the soc i And the current upper limit of battery capacity Q of the corresponding battery cell due to factors such as aging imax Calculate the remaining discharge capacity Q of battery cluster i 1i ; or under charging conditions, the maximum soc of the cells in battery cluster i is taken as soc i , according to the maximum soc of the cells in the cluster i And the corresponding battery current capacity upper limit Q imax Calculate the remaining chargeable capacity Q of each cluster 2i ;

[0114] The remaining discharge capacity under discharge conditions is determined by the following formula (2):

[0115] Q 1i =soc i *Q imax ; (2)

[0116] Among them, Q 1i SOC is the remaining discharge capacity of the battery cluster under discharge conditions. i is the initial remaining power state of the battery cluster, Q imax The upper limit of the battery capacity of the battery cluster.

[0117] The remaining chargeable capacity under charging conditions is determined by the following formula (3):

[0118] Q 2i =(1-soc i )*Qimax ; (3)

[0119] Among them, Q 2i SOC is the remaining chargeable capacity of the battery cluster under charging conditions. i is the initial remaining power state of the battery cluster, Q imax The upper limit of the battery capacity of the battery cluster.

[0120] It should be noted that, in the formula (2) described in the embodiment of the present application, the initial remaining power state and the upper limit of the battery capacity of the battery cluster under the discharge condition are determined based on the battery cell corresponding to the minimum soc of the battery cell in the cluster; in the formula (3) described in the embodiment of the present application, the initial remaining power state and the upper limit of the battery capacity of the battery cluster under the charging condition are determined based on the battery cell corresponding to the maximum soc of the battery cell in the cluster. In this way, the remaining chargeable capacity and the remaining dischargeable capacity of the battery cluster are calculated more accurately.

[0121] Based on the above method (2) and formula (3), the current distribution ratio is calculated according to the proportion of the remaining chargeable and dischargeable capacity.

[0122] The current distribution ratio under discharge conditions is determined by the following formula (4):

[0123]

[0124] Among them, I i，disch，pct Characterizes the current distribution ratio of battery cluster i under discharge conditions.

[0125] The current distribution ratio under charging conditions is determined by the following formula (5):

[0126]

[0127] I i，ch，pct Characterizes the current distribution ratio of battery cluster i under charging conditions.

[0128] Under static conditions, the current distribution ratio of each parallel cluster is uniformly distributed by default, that is, the current distribution ratio of the battery cluster is calculated according to formula (1).

[0129] After determining the current distribution ratio of the battery cluster, the true value of the controlled current source of the equivalent model of the DC / DC module connected in series with the battery cluster is calculated.

[0130] Based on the above formulas (4) and (5), the true value of the controlled current source under discharge conditions is determined by the following formula (6):

[0131] I i =I i，disch，pct *I Bus (6)

[0132] Among them, Ii Characterizes the true value of the controlled current source, I Bus Characterizes the bus current.

[0133] The true value of the controlled current source under charging conditions is determined by the following formula (7):

[0134] I i =I i，ch，pct *I Bus (7)

[0135] Among them, I i Characterizes the true value of the controlled current source, I Bus Characterizes the bus current.

[0136] Due to problems such as calculation accuracy, the sum of the true values ​​of the controlled current sources may not be 100% of the bus current. Therefore, in the embodiment of the present application, at least one balancing node is determined for proportional compensation. After the above algorithm, when the current true values ​​of the equivalent series controlled current sources of all DC / DC modules are calculated, the DC / DC module of the cluster with the largest current chargeable or dischargeable capacity is taken as the main control node. The main control node is used as a balancing node, and the value of its equivalent series controlled current source follows the difference between the sum of the current true values ​​calculated by each cluster and the bus current, thereby achieving system balance.

[0137] The true value of the current of the master node is determined by the following formula (8):

[0138]

[0139] Among them, I slack Characterizes the true value of the current at the balancing node.

[0140] According to the calculated true current value of each cluster, the true current value of the series controlled current source of the equivalent DCDC model is allocated to simulate the SOC change during the charging and discharging process of the energy storage system.

[0141] The bus voltage is stabilized and controlled by a controlled voltage source connected in parallel on the DC bus side. In the embodiment of the present application, its voltage value is the minimum battery cluster terminal voltage of all currently connected cabinet battery clusters plus 20V, so that the series DC / DC voltage regulation capability is 10V~20V.

[0142] Figure 8 The soc simulation results of the energy storage system model described in the embodiment of the present application are shown, such as Figure 8 As shown, after controlling the current of each battery cluster for charging and discharging according to the current distribution rule described in the embodiment of the present application, the soc of each cluster of the voltage stabilizing system simultaneously reaches 100% in a charging condition or simultaneously reaches 0% in a discharging condition.

[0143] Based on the simulation results of the voltage stabilization system model, the current distribution rule corresponding to each working condition is determined.

[0144] It should be noted that the preset balance threshold used to determine whether the initial remaining power state of the system is balanced is determined by simulation of the voltage stabilization system model. For example, after simulation, it is determined that the preset balance threshold is set to 0.5%, and the simulation result can meet the user's soc balance requirements, then the preset balance threshold is set to 0.5%.

[0145] In step S102, a target battery cluster that is put into operation under a target operating condition of the energy storage system is determined, and an initial remaining power state of the target battery cluster is obtained.

[0146] Different energy storage systems have different numbers of battery clusters. Battery clusters are part of an energy storage system. When building an energy storage system, the number of battery clusters is determined based on the required energy storage capacity and the system's operating requirements. For example, if a large amount of energy needs to be stored and there is enough space, more battery clusters may be selected; if space is limited, fewer battery clusters may be selected; in addition, the way the battery modules are connected may also affect the number of battery clusters. Therefore, in specific practical applications, the number of battery clusters used in different energy storage systems may vary due to a variety of factors.

[0147] The number of battery clusters actually put into operation may also be different under different working conditions of the energy storage system. The number of battery clusters actually in operation in the energy storage system may be less than the minimum number of battery clusters corresponding to the total battery capacity. In actual operation, due to factors such as the characteristics and usage of the energy storage system, the actual operating state of the battery may deviate from the ideal state. For example, battery parameters such as voltage and current may change, resulting in the battery capacity not being fully utilized, thereby reducing the number of battery clusters actually in operation. For example, when charging is about to be completed, the charging current decreases, resulting in a reduction in the number of battery clusters actually in operation. In addition, if a battery fails or is damaged during use, the number of battery clusters actually in operation may also be reduced.

[0148] Therefore, it is necessary to determine the target battery cluster that the energy storage system actually puts into operation under the target operating conditions.

[0149] Get the initial remaining power status of the target battery cluster, including:

[0150] When the target operating condition is a charging operating condition, determining the maximum initial remaining power state of the cells in the battery cluster as the initial remaining power state of the target battery cluster;

[0151] When the target operating condition is a discharging operating condition, the minimum initial remaining power state of the cells in the battery cluster is determined as the initial remaining power state of the target battery cluster.

[0152] When the target operating condition is a charging condition, the maximum initial remaining power state of the battery cells in the battery cluster is determined as the initial remaining power state of the target battery cluster. This is because if a smaller initial remaining power is selected, some cells in the battery cluster may be undercharged, thereby affecting the performance and service life of the entire battery cluster.

[0153] When the target operating condition is a discharge condition, the minimum initial remaining power state of the battery cells in the battery cluster is determined as the initial remaining power state of the target battery cluster. This is because if a larger initial remaining power is selected, some of the battery cells in the battery cluster may be over-discharged, thereby damaging the battery cells in the battery cluster and even causing failure of the entire battery cluster.

[0154] Therefore, when selecting the initial remaining charge state of the target battery cluster, it is necessary to comprehensively consider the target operating conditions and the specific conditions of the battery cluster to determine the most appropriate initial remaining charge state.

[0155] It should be noted that, during the actual charging and discharging process, it is necessary to redetermine the target current distribution ratio of the target battery cluster in real time according to the preset update duration, and also to redetermine the initial remaining power state of the target battery cluster. Therefore, the initial remaining power state is the minimum or maximum SOC of the current battery cell in the cluster, and the state of the battery cell will also change continuously during the charging and discharging process, and the battery cell corresponding to the minimum or maximum SOC will also change continuously, thereby achieving an overall dynamic balance during the entire charging and discharging process.

[0156] In step S103, the target current distribution ratio of the target battery cluster is determined based on the target current distribution rule corresponding to the target operating condition and / or the initial remaining power state of the target battery cluster.

[0157] Specifically, when the target operating condition is a static operating condition, the current ratio is evenly distributed according to the number of target battery clusters. Please refer to formula (1) in the embodiment of the application.

[0158] When the target operating conditions are charging and discharging conditions, whether the energy storage system meets the preset balancing conditions is determined according to the initial remaining power state of the target battery cluster;

[0159] If it meets the requirement, the current ratio is evenly distributed according to the number of target battery clusters;

[0160] If not, the remaining power change capacity is determined according to the initial remaining power state and the target power state;

[0161] Based on the proportional relationship between the remaining power change capacities of different target battery clusters, the target current distribution ratio of the target battery cluster is determined.

[0162] The preset balancing condition is a condition for judging whether the initial remaining power state of all target battery clusters put into operation in the energy storage system is balanced, thereby judging the SOC balancing performance of the entire energy storage system. When judging whether the energy storage system meets the preset balancing condition, a comprehensive judgment is required based on the initial remaining power state of each battery cluster.

[0163] In the embodiment of the present application, judging whether the energy storage system meets the preset balancing condition according to the initial remaining power state of the target battery cluster includes:

[0164] Determining a balancing parameter of the energy storage system according to the initial remaining power state of the target battery cluster; wherein the balancing parameter is used to characterize the difference in initial remaining power of different target battery clusters;

[0165] It is determined whether the equalization parameter is less than a preset equalization threshold.

[0166] During the battery balancing process, balancing parameters are needed to describe the differences in the initial remaining capacities of different target battery clusters.

[0167] Exemplarily, the balancing parameters may include the maximum initial remaining capacity, the minimum initial remaining capacity, the standard deviation of the initial remaining capacity, etc. Through the balancing parameters, the initial remaining capacities of different target battery clusters may be compared and evaluated, so as to judge the SOC balancing performance of the energy storage system according to the balancing parameters, and adopt different rules to control the target current distribution ratio of the target battery cluster in the charging and discharging conditions based on the judgment results.

[0168] It is determined whether the balancing parameter is less than a preset balancing threshold value, that is, whether the SOC difference between the battery clusters exceeds an acceptable range according to whether the balancing parameter is less than the preset balancing threshold value; when the balancing parameter is less than the preset balancing threshold value, it indicates that the SOC difference between the battery clusters does not exceed an acceptable range, and formula (1) can be used to evenly distribute the current ratio according to the number of target battery clusters; when it exceeds the preset balancing threshold value, it indicates that the SOC difference between the battery clusters does not exceed an acceptable range, and the target current distribution ratio of the target battery cluster is determined based on the proportional relationship between the remaining power change capacity of different target battery clusters.

[0169] It should be noted that different balancing thresholds may lead to different results. A lower balancing threshold can more accurately detect the SOC difference between battery clusters, but it may increase energy consumption, increase the amount of calculation, and increase the difficulty of current distribution. Therefore, it is necessary to select an appropriate balancing threshold according to specific needs.

[0170] In the embodiment of the present application, the preset balancing threshold is obtained by simulating a pre-built energy storage system based on the user's requirements for SOC balancing performance, thereby obtaining a preset balancing threshold that meets the accuracy requirements but is not overly detailed.

[0171] In the embodiment of the present application, the step of determining the balancing parameters of the energy storage system according to the initial remaining power of the target battery cluster includes:

[0172] Determine a maximum initial remaining power state and a minimum initial remaining power state of a target battery cluster of the energy storage system;

[0173] The difference between the maximum initial remaining power state and the minimum initial remaining power state is determined as a balancing parameter of the energy storage system.

[0174] By calculating the difference between the maximum initial remaining power state and the minimum initial remaining power state, the equilibrium state differences of different battery clusters in the energy storage system are maximized for quantitative evaluation, thereby more accurately evaluating the equilibrium state of the energy storage system.

[0175] In the embodiment of the present application, when the initial remaining power state of the target battery cluster determines that the energy storage system does not meet the preset balancing condition, it is necessary to determine the remaining power change capacity according to the initial remaining power state and the target power state;

[0176] Based on the proportional relationship between the remaining power change capacities of different target battery clusters, the target current distribution ratio of the target battery cluster is determined.

[0177] In the embodiment of the present application, the remaining power change capacity is determined according to the initial remaining power state and the target power state; including:

[0178] When the target operating condition is a discharge operating condition, the remaining dischargeable capacity when the remaining power state is 0 is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity;

[0179] When the target operating condition is a charging operating condition, the remaining chargeable capacity when charging to the remaining power state of 100% is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity;

[0180] The battery capacity upper limit represents the capacity upper limit of the battery cluster when operating in a target operating condition.

[0181] Here, the upper limit of the battery capacity is determined according to the battery cells in the battery cluster whose initial remaining power state is determined.

[0182] Specifically, according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity, determining the remaining dischargeable capacity when discharging to the remaining power state of 0 includes:

[0183] The product of the initial remaining power state of the target battery cluster and the upper limit of the battery capacity is determined as the remaining discharge capacity.

[0184] Specifically, please refer to formula (2) to calculate the remaining discharge capacity of the target battery cluster.

[0185] When the target operating condition is a charging operating condition, the remaining chargeable capacity when charging to the remaining power state of 100% is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity, including:

[0186] Determine a difference percentage between an initial state of charge remaining of the target battery cluster and a state of charge remaining of 100%;

[0187] The product of the difference percentage of the target battery cluster and the upper limit of the battery capacity is determined as the remaining chargeable capacity.

[0188] Specifically, please refer to formula (3) to calculate the remaining discharge capacity of the target battery cluster.

[0189] After calculating the remaining discharge capacity or remaining charge capacity of the target battery cluster, the target current distribution ratio of the target battery cluster is determined based on the proportional relationship between the remaining power change capacities of different target battery clusters, specifically including:

[0190] Calculate the sum of the remaining power change capacity of all target battery clusters;

[0191] Calculate the ratio of the remaining power change capacity of each target battery cluster to the sum of the remaining power change capacities;

[0192] The ratio of each target battery cluster is determined as the target current distribution ratio of the target battery cluster.

[0193] Specifically, for charging and discharging conditions, please refer to formula (4) and formula (5) to determine the target current distribution ratio.

[0194] In step S104 described in the embodiment of the present application, the current in the target battery cluster is controlled according to the target current distribution ratio, so that the charge states of different target battery clusters of the energy storage system under the target working condition change evenly.

[0195] Specifically, controlling the current in the target battery cluster according to the target current distribution ratio includes:

[0196] The output current of the DC / DC modules connected in series to the target battery cluster is controlled and distributed according to the target current distribution ratio, so as to control the current size in the target battery cluster.

[0197] That is to say, according to the target current distribution ratio, the total current is divided into several parts corresponding to different battery clusters; by controlling the output current size of the DC / DC module connected in series with the battery cluster, the current of each battery cluster is controlled to the allocated current value.

[0198] In the actual control process, sensors can be used to monitor the current size of each battery cluster, and the output current of the DC / DC module can be adjusted in real time based on the monitoring results; for example, based on the sensor monitoring the current size of each battery cluster, the current size of the battery cluster can be controlled through a PID control algorithm or other control algorithms.

[0199] Based on this, in the embodiment of the present application, in the balanced control method of the energy storage system, the current size in the target battery cluster is controlled according to the target current distribution ratio, including:

[0200] Based on the pre-calculated and real-time remaining power change capacity of the target battery cluster, determine the battery cluster with the largest remaining power change capacity as the master control node;

[0201] Controlling and distributing the current of each target battery cluster in series according to the target current distribution ratio;

[0202] Based on the sum of the currents of the target battery clusters other than the master control node, the current in the battery cluster serving as the master control node is adjusted so that the sum of the currents of all the target battery clusters is equal to the bus current of the energy storage system.

[0203] In actual operation, due to problems such as calculation accuracy, the sum of the true values ​​of the controlled current sources may not be 100% of the bus current. Therefore, in an embodiment of the present application, the DC / DC module of the cluster with the largest current chargeable or dischargeable capacity is taken as the main control node, and the main control node is used as a balancing node. The current value of the main control node follows the difference between the sum of the current values ​​of each cluster and the bus current, thereby achieving system balance.

[0204] The balanced control method of the energy storage system described in the embodiment of the present application is to perform real-time dynamic control during the operation of the energy storage system. It is necessary to continuously update the target current distribution ratio according to the real-time operating conditions of the energy storage system and the initial remaining power state of the target battery cluster, so that the overall charging and discharging process of the entire energy storage system reaches a dynamic balance, so that the soc of each cluster of the system reaches 100% at the same time in a charging condition or reaches 0% at the same time in a discharging condition, and Δsoc meets the requirements, so that different clusters correct the soc to be consistent in one condition, and maintain the maximum Δsoc to meet the requirements in subsequent charging and discharging conditions.

[0205] Based on this, the balanced control method of the energy storage system described in the embodiment of the present application also includes:

[0206] When it is detected that a preset update condition is met, updating the target current distribution ratio;

[0207] updating the current size in the target battery cluster according to the updated target current distribution ratio;

[0208] The preset update conditions include: the target operating condition of the energy storage system changes, the target battery cluster put into operation changes, and the energy storage system is updated according to the preset collection frequency.

[0209] When the preset update conditions are met, the target current distribution ratio will be updated, and the current size in the target battery cluster will be updated accordingly, so that the target current of each battery cluster will be recalculated and distributed to adapt to the new target operating conditions, battery cluster combination or other operating conditions.

[0210] Specifically, when the target operating condition changes, that is, when the target operating condition of the energy storage system changes, such as switching from a charging condition to a discharging condition, or performing alternating charging and discharging, this may cause the current demand of the battery cluster to change. Therefore, the current distribution ratio may be updated at this time.

[0211] The target battery cluster put into operation changes: If the target battery cluster put into operation in the energy storage system changes, for example, a new battery cluster is added or removed, the current demand of the battery cluster also changes. At this time, in order to ensure the SOC balance of the system, the current distribution ratio also needs to be updated.

[0212] Update according to the preset collection frequency. Specifically, as the charging and discharging process proceeds, the initial remaining power state of the target battery cluster continues to change, and the original target current distribution ratio may no longer be in line with the current target battery cluster; therefore, during operation, it is necessary to update the target current distribution ratio according to the initial remaining power of the target battery cluster in real time; specifically, the target current distribution ratio is updated according to a certain current distribution ratio calculation frequency.

[0213] In some embodiments, the current sharing ratio calculation frequency is determined according to the BMS sampling frequency, for example, the same as the BMS sampling frequency.

[0214] After the target current distribution ratio is updated, the current size in the target battery cluster is updated, that is, the current of each battery cluster is adjusted to the size corresponding to the new current distribution ratio by controlling the DC / DC module.

[0215] As the charging and discharging process proceeds, the initial remaining power state of the target battery cluster keeps changing, and the battery cluster with the largest remaining power change capacity may also change. Therefore, the master control node keeps changing according to the actual system capacity during operation and is always determined by the battery cluster with the largest available capacity.

[0216] That is to say, during the operation of the energy storage system, the master control node is always assumed by the cluster with the largest available capacity during operation.

[0217] That is to say, before the update, the current value of the original master control node follows the difference between the sum of the current values ​​of other clusters and the bus current. After the update, the current value of the original master control node is determined based on its corresponding target current distribution ratio, and the current value of the new master control node follows the difference between the sum of the current values ​​of other clusters and the bus current.

[0218] The DC / DC module of the cluster with the largest current chargeable or dischargeable capacity is used as the master control node for current balancing because the DC / DC module of the cluster with the largest current chargeable or dischargeable capacity has the highest fault tolerance, thereby further ensuring the SOC balance of the entire energy storage system.

[0219] Based on the same inventive concept, an embodiment of the present application also provides a balancing control device for an energy storage system corresponding to the balancing control method for an energy storage system. Since the principle of solving the problem by the device in the embodiment of the present application is similar to the balancing control method for the energy storage system in the embodiment of the present application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0220] Please refer to Fig. 9 , Fig. 9 The schematic diagram of the structure of the balancing control device of the energy storage system according to the embodiment of the present application is shown. The energy storage system includes a plurality of battery clusters, each battery cluster is connected in series with a DC / DC module; the balancing control device includes:

[0221] The first determination module 901 is used to determine the current distribution rules in the battery cluster of the energy storage system under various working conditions; wherein the current distribution rules are used to determine the current distribution ratio of the battery cluster put into operation based on the initial remaining power state; different working conditions correspond to different current distribution rules; the working conditions include charging working conditions, discharging working conditions, and static working conditions;

[0222] An acquisition module 902 is used to determine a target battery cluster that is put into operation under a target operating condition of the energy storage system, and to acquire an initial remaining power state of the target battery cluster;

[0223] A second determination module 903, configured to determine a target current distribution ratio of a target battery cluster based on a target current distribution rule corresponding to a target operating condition and / or an initial remaining power state of a target battery cluster;

[0224] The control module 904 is used to control the current in the target battery cluster according to the target current distribution ratio, so that the charge states of different target battery clusters of the energy storage system under the target working condition change evenly.

[0225] The embodiment of the present application provides a balancing control device for an energy storage system, wherein the energy storage system includes a plurality of battery clusters, each battery cluster being connected in series with a DC / DC module; the balancing control device is used to determine a current distribution rule in a battery cluster of the energy storage system under a plurality of operating conditions; wherein the current distribution rule is used to determine a current distribution ratio of a battery cluster put into operation based on an initial remaining power state; different operating conditions correspond to different current distribution rules; the operating conditions include a charging operating condition, a discharging operating condition, and a static operating condition; a target battery cluster put into operation by the energy storage system under a target operating condition is determined, and an initial remaining power state of the target battery cluster is obtained; a target current distribution rule corresponding to the target operating condition, and / or an initial remaining power state of the target battery cluster are determined; and ... current distribution ratio of a battery cluster put into operation is determined; and The target current distribution ratio of the target battery cluster is determined according to the target current distribution ratio; the current size in the target battery cluster is controlled according to the target current distribution ratio, so that the power state of different target battery clusters of the energy storage system under the target working condition changes evenly; in this way, by providing the current distribution ratio to the battery cluster put into operation, the current in the target battery cluster with the initial residual power state changes according to the current distribution ratio, so that the soc of each target battery cluster of the system reaches 100% at the same time in a charging condition or reaches 0% at the same time in a discharging condition, and the soc of each cluster is consistent during operation and after entering the static condition, so as to reduce the difference in the sum of the ocv of the battery cells of each cluster, and avoid the inter-cluster circulation through the DC / DC module.

[0226] In some embodiments, in the balancing control device of the energy storage system, the second determination module determines the target current distribution ratio of the target battery cluster based on the target current distribution rule corresponding to the target operating condition and / or the initial remaining power state of the target battery cluster, and is specifically used to:

[0227] When the target operating condition is a stationary condition, the current ratio is evenly distributed according to the number of target battery clusters.

[0228] In some embodiments, in the balancing control device of the energy storage system, the second determination module, when determining the target current distribution ratio of the target battery cluster based on the target current distribution rule corresponding to the target operating condition and / or the initial remaining power state of the target battery cluster, is specifically used to:

[0229] When the target operating conditions are charging and discharging conditions, whether the energy storage system meets the preset balancing conditions is determined according to the initial remaining power state of the target battery cluster;

[0230] If it meets the requirement, the current ratio is evenly distributed according to the number of target battery clusters;

[0231] If not, the remaining power change capacity is determined according to the initial remaining power state and the target power state;

[0232] Based on the proportional relationship between the remaining power change capacities of different target battery clusters, the target current distribution ratio of the target battery cluster is determined.

[0233] In some embodiments, in the balancing control device for the energy storage system, the second determination module, when judging whether the energy storage system meets the preset balancing condition according to the initial remaining power state of the target battery cluster, is specifically used to:

[0234] Determining a balancing parameter of the energy storage system according to the initial remaining power state of the target battery cluster; wherein the balancing parameter is used to characterize the difference in initial remaining power of different target battery clusters;

[0235] It is determined whether the equalization parameter is less than a preset equalization threshold.

[0236] In some embodiments, in the balancing control device for the energy storage system, the second determination module, when determining the balancing parameters of the energy storage system according to the initial remaining power of the target battery cluster, is specifically used to:

[0237] Determine a maximum initial remaining power state and a minimum initial remaining power state of a target battery cluster of the energy storage system;

[0238] The difference between the maximum initial remaining power state and the minimum initial remaining power state is determined as a balancing parameter of the energy storage system.

[0239] In some embodiments, in the energy storage system balancing control device, the remaining power change capacity includes the remaining chargeable capacity under charging conditions and the remaining dischargeable capacity under discharging conditions;

[0240] The second determination module, when determining the remaining power change capacity according to the initial remaining power state and the target power state, is specifically used to:

[0241] When the target operating condition is a discharge operating condition, the remaining dischargeable capacity when the remaining power state is 0 is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity;

[0242] When the target operating condition is a charging operating condition, the remaining chargeable capacity when charging to the remaining power state of 100% is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity;

[0243] The battery capacity upper limit represents the capacity upper limit of the battery cluster when operating in a target operating condition.

[0244] In some embodiments, in the balancing control device of the energy storage system, the second determination module determines the remaining dischargeable capacity when the remaining power state is 0 according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity, including:

[0245] Determine the product of the initial remaining power state of the target battery cluster and the upper limit of the battery capacity as the remaining discharge capacity;

[0246] When determining the remaining chargeable capacity when charging to the remaining charge state of 100% according to the initial remaining charge state of the target battery cluster and the upper limit of the battery capacity, it is specifically used for:

[0247] Determine a difference percentage between an initial state of charge remaining of the target battery cluster and a state of charge remaining of 100%;

[0248] The product of the difference percentage of the target battery cluster and the upper limit of the battery capacity is determined as the remaining chargeable capacity.

[0249] In some embodiments, the second determination module in the balancing control device of the energy storage system, when determining the target current distribution ratio of the target battery cluster based on the proportional relationship between the remaining power change capacities of different target battery clusters, is specifically used to:

[0250] Calculate the sum of the remaining power change capacity of all target battery clusters;

[0251] Calculate the ratio of the remaining power change capacity of each target battery cluster to the sum of the remaining power change capacities;

[0252] The ratio of each target battery cluster is determined as the target current distribution ratio of the target battery cluster.

[0253] In some embodiments, the control module in the balancing control device of the energy storage system, when controlling the current size in the target battery cluster according to the target current distribution ratio, is specifically used to:

[0254] The output current of the DC / DC modules connected in series to the target battery cluster is controlled and distributed according to the target current distribution ratio, so as to control the current size in the target battery cluster.

[0255] In some embodiments, the control module in the balancing control device of the energy storage system, when controlling the current size in the target battery cluster according to the target current distribution ratio, is specifically used to:

[0256] Based on the pre-calculated and real-time remaining power change capacity of the target battery cluster, determine the battery cluster with the largest remaining power change capacity as the master control node;

[0257] Controlling and distributing the current of each target battery cluster in series according to the target current distribution ratio;

[0258] Based on the sum of the currents of the target battery clusters other than the master control node, the current in the battery cluster serving as the master control node is adjusted so that the sum of the currents of all the target battery clusters is equal to the bus current of the energy storage system.

[0259] In some embodiments, the balancing control device of the energy storage system further includes:

[0260] An updating module, configured to update the target current distribution ratio when it is detected that a preset updating condition is met;

[0261] updating the current size in the target battery cluster according to the updated target current distribution ratio;

[0262] The preset update conditions include: the target operating condition of the energy storage system changes, the target battery cluster put into operation changes, and the energy storage system is updated according to the preset collection frequency.

[0263] In some embodiments, the first determination module in the balancing control device of the energy storage system is specifically used to determine the current distribution rules in the battery cluster of the energy storage system under various working conditions:

[0264] Determine the equivalent model of the DC / DC module connected in series with the target battery cluster in the energy storage system; wherein; when the relay of the target battery cluster is opened, the DC / DC module connected in series with the target battery cluster is equivalent to a series controlled voltage source; when the relay of the target battery cluster is closed, the DC / DC module connected in series with the target battery cluster is equivalent to a series controlled current source;

[0265] Based on the equivalent model of DC / DC module, the energy storage system model is constructed;

[0266] Based on the constructed energy storage system model, the process of voltage regulation of the target battery cluster within the preset voltage regulation range through the DC / DC module is simulated by a series controlled voltage source. The process of operation of the target battery cluster according to the current distribution ratio through the DC / DC module is simulated by a series controlled current source. The current distribution rules in the battery cluster of the energy storage system under various working conditions are determined.

[0267] In some embodiments, in the first determination module in the balancing control device of the energy storage system, the equivalent model of the DC / DC module of the target battery cluster in series in the energy storage system includes: a relay, a series controlled voltage source, a series controlled current source, and a switching circuit;

[0268] When the relay is opened, the switching circuit is driven to switch to a state where the voltage source is connected in series with the target battery cluster; when the relay is closed, the switching circuit is driven to switch to a state where the current source is connected in series with the target battery cluster.

[0269] In some embodiments, the acquisition module in the balancing control device of the energy storage system, when acquiring the initial remaining power state of the target battery cluster, is specifically used to:

[0270] When the target operating condition is a charging operating condition, determining the maximum initial remaining power state of the cells in the battery cluster as the initial remaining power state of the target battery cluster;

[0271] When the target operating condition is a discharging operating condition, the minimum initial remaining power state of the cells in the battery cluster is determined as the initial remaining power state of the target battery cluster.

[0272] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the method embodiment, and will not be repeated in this application. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0273] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0274] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0275] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a platform server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard drives, ROM, RAM, magnetic disks, or optical disks.

[0276] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A balanced control method for an energy storage system, characterized in that: The energy storage system includes a plurality of battery clusters, each battery cluster being connected in series with a DC / DC module; The balancing control method comprises: Determine the current distribution rules in the battery cluster of the energy storage system under various working conditions; wherein the current distribution rules are used to determine the current distribution ratio of the battery cluster put into operation based on the initial remaining power state; different working conditions correspond to different current distribution rules; the working conditions include charging working conditions, discharging working conditions, and static working conditions; Determine the target battery cluster that the energy storage system is put into operation under the target operating conditions, and obtain the initial remaining power state of the target battery cluster; Determining a target current distribution ratio of the target battery cluster based on a target current distribution rule corresponding to the target operating condition and / or an initial remaining power state of the target battery cluster; The current in the target battery cluster is controlled according to the target current distribution ratio, so that the charge states of different target battery clusters of the energy storage system under the target working condition change evenly.

2. The balanced control method of the energy storage system according to claim 1, characterized in that: Determining a target current distribution ratio of the target battery cluster based on a target current distribution rule corresponding to the target operating condition and / or an initial remaining power state of the target battery cluster includes: When the target operating condition is a stationary condition, the current ratio is evenly distributed according to the number of target battery clusters.

3. The balanced control method of the energy storage system according to claim 1, characterized in that: Determining a target current distribution ratio of the target battery cluster based on a target current distribution rule corresponding to the target operating condition and / or an initial remaining power state of the target battery cluster includes: When the target operating conditions are charging and discharging conditions, whether the energy storage system meets the preset balancing conditions is determined according to the initial remaining power state of the target battery cluster; If it meets the requirement, the current ratio is evenly distributed according to the number of target battery clusters; If not, the remaining power change capacity is determined according to the initial remaining power state and the target power state; Based on the proportional relationship between the remaining power change capacities of different target battery clusters, the target current distribution ratio of the target battery cluster is determined.

4. The balanced control method of the energy storage system according to claim 3, characterized in that: Determine whether the energy storage system meets the preset balancing conditions based on the initial remaining power state of the target battery cluster, including: Determining a balancing parameter of the energy storage system according to the initial remaining power state of the target battery cluster; wherein the balancing parameter is used to characterize the difference in initial remaining power of different target battery clusters; It is determined whether the equalization parameter is less than a preset equalization threshold.

5. The balanced control method of the energy storage system according to claim 4, characterized in that: The balancing parameters of the energy storage system are determined according to the initial remaining power of the target battery cluster, including: Determine a maximum initial remaining power state and a minimum initial remaining power state of a target battery cluster of the energy storage system; The difference between the maximum initial remaining power state and the minimum initial remaining power state is determined as a balancing parameter of the energy storage system.

6. The balanced control method of the energy storage system according to claim 4, characterized in that: The remaining capacity variation includes the remaining chargeable capacity under charging conditions and the remaining dischargeable capacity under discharging conditions; Determine the remaining power change capacity according to the initial remaining power state and the target power state; including: When the target operating condition is a discharge operating condition, the remaining dischargeable capacity when the remaining power state is 0 is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity; When the target operating condition is a charging operating condition, the remaining chargeable capacity when charging to the remaining power state of 100% is determined according to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity; The battery capacity upper limit represents the capacity upper limit of the battery cluster when operating in a target operating condition.

7. The balanced control method of the energy storage system according to claim 6, characterized in that: According to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity, the remaining dischargeable capacity when the remaining power state is discharged to 0 is determined, including: Determine the product of the initial remaining power state of the target battery cluster and the upper limit of the battery capacity as the remaining discharge capacity; According to the initial remaining power state of the target battery cluster and the upper limit of the battery capacity, the remaining chargeable capacity when charging to the remaining power state of 100% is determined, including: Determine a difference percentage between an initial state of charge remaining of the target battery cluster and a state of charge remaining of 100%; The product of the difference percentage of the target battery cluster and the upper limit of the battery capacity is determined as the remaining chargeable capacity.

8. The balanced control method of the energy storage system according to claim 3, characterized in that: Based on the proportional relationship between the remaining power change capacities of different target battery clusters, the target current distribution ratio of the target battery cluster is determined, including: Calculate the sum of the remaining power change capacity of all target battery clusters; Calculate the ratio of the remaining power change capacity of each target battery cluster to the sum of the remaining power change capacities; The ratio of each target battery cluster is determined as the target current distribution ratio of the target battery cluster.

9. The balanced control method of the energy storage system according to claim 1, characterized in that: Controlling the current size in the target battery cluster according to the target current distribution ratio includes: The output current of the DC / DC modules connected in series to the target battery cluster is controlled and distributed according to the target current distribution ratio, so as to control the current size in the target battery cluster.

10. The balanced control method of the energy storage system according to claim 1, characterized in that: Controlling the current size in the target battery cluster according to the target current distribution ratio includes: Based on the pre-calculated and real-time remaining power change capacity of the target battery cluster, determine the battery cluster with the largest remaining power change capacity as the master control node; Controlling and distributing the current of each target battery cluster in series according to the target current distribution ratio; Based on the sum of the currents of the target battery clusters other than the master control node, the current in the battery cluster serving as the master control node is adjusted so that the sum of the currents of all the target battery clusters is equal to the bus current of the energy storage system.

11. The balanced control method of the energy storage system according to claim 1, characterized in that: The method further comprises: When it is detected that a preset update condition is met, updating the target current distribution ratio; updating the current size in the target battery cluster according to the updated target current distribution ratio; The preset update conditions include: the target operating condition of the energy storage system changes, the target battery cluster put into operation changes, and the energy storage system is updated according to the preset collection frequency.

12. The balanced control method of the energy storage system according to claim 1, characterized in that: Determine the current distribution rules in the battery cluster of the energy storage system under various operating conditions, including: Determine the equivalent model of the DC / DC module connected in series with the target battery cluster in the energy storage system; wherein; when the relay of the target battery cluster is opened, the DC / DC module connected in series with the target battery cluster is equivalent to a series controlled voltage source; when the relay of the target battery cluster is closed, the DC / DC module connected in series with the target battery cluster is equivalent to a series controlled current source; Based on the equivalent model of DC / DC module, the energy storage system model is constructed; Based on the constructed energy storage system model, the process of voltage regulation of the target battery cluster within the preset voltage regulation range through the DC / DC module is simulated by a series controlled voltage source. The process of operation of the target battery cluster according to the current distribution ratio through the DC / DC module is simulated by a series controlled current source. The current distribution rules in the battery cluster of the energy storage system under various working conditions are determined.

13. The balanced control method of the energy storage system according to claim 11, characterized in that: An equivalent model of a DC / DC module of a target battery cluster in series in an energy storage system, including: a relay, a series controlled voltage source, a series controlled current source, and a switching circuit; When the relay is opened, the switching circuit is driven to switch to a state where the voltage source is connected in series with the target battery cluster; when the relay is closed, the switching circuit is driven to switch to a state where the current source is connected in series with the target battery cluster.

14. The balanced control method of the energy storage system according to claim 1, characterized in that: The obtaining of the initial remaining power state of the target battery cluster includes: When the target operating condition is a charging operating condition, determining the maximum initial remaining power state of the cells in the battery cluster as the initial remaining power state of the target battery cluster; When the target operating condition is a discharging operating condition, the minimum initial remaining power state of the cells in the battery cluster is determined as the initial remaining power state of the target battery cluster.

15. A balancing control device for an energy storage system, characterized in that: The energy storage system includes a plurality of battery clusters, each battery cluster being connected in series with a DC / DC module; The balancing control device comprises: The first determination module is used to determine the current distribution rules in the battery cluster of the energy storage system under various working conditions; wherein the current distribution rules are used to determine the current distribution ratio of the battery cluster put into operation based on the initial remaining power state; different working conditions correspond to different current distribution rules; the working conditions include charging working conditions, discharging working conditions, and static working conditions; An acquisition module is used to determine a target battery cluster that is put into operation under a target operating condition of the energy storage system, and to obtain an initial remaining power state of the target battery cluster; A second determination module, configured to determine a target current distribution ratio of a target battery cluster based on a target current distribution rule corresponding to a target operating condition and / or an initial remaining power state of the target battery cluster; The control module is used to control the current in the target battery cluster according to the target current distribution ratio, so that the power states of different target battery clusters of the energy storage system under the target working condition change evenly.

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