Control method and apparatus, electronic device, and storage medium

Abstract

Provided are a control method and apparatus, an electronic device, and a storage medium. The method comprises: issuing alternating-current active power to corresponding bidirectional energy storage converters so as to adjust current distributed by each bidirectional energy storage converter; and controlling each direct-current power converter on the basis of a target current distribution ratio so as to adjust current distributed to each battery cluster. By controlling alternating-current active power issued to the bidirectional energy storage converters to be a given value, the current of each direct-current bus is controlled, so that battery stacks are simultaneously fully charged or fully discharged; in addition, the current is distributed on the basis of the current ratio of battery clusters in a same stack to reduce system differences, thereby greatly improving the consistency, service life, working efficiency and depth of charge and discharge of a whole battery energy storage system.

Description

Control method, device, electronic device and storage medium

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese patent application number 2023118328560, filed with the State Intellectual Property Office of China on December 27, 2023, entitled “A control method, device, electronic device and storage medium,” the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] The present disclosure relates to the field of circuit control technology, and in particular to a control method, device, electronic device, and storage medium. Background Art

[0004] The power of a single battery cluster is no longer sufficient to meet human needs. To meet people's ever-increasing power demands, battery energy storage systems have emerged. A battery energy storage system consists of multiple battery stacks connected in parallel, each of which is composed of multiple battery clusters connected in parallel. To extend the life of a battery energy storage system, it is necessary to ensure that the remaining charge in each battery cluster remains at the same level during use (charging and discharging).

[0005] Existing technologies distribute current among battery clusters based on their capacity ratios. This method of distribution has poor accuracy, and during use, some battery stacks may reach full charge or full discharge before others, causing them to exit the operating state at different times than other battery stacks, affecting the utilization rate and depth of discharge (DoD) of the entire energy storage system.

[0006] Summary of the Invention

[0007] In view of this, an object of the present disclosure is to provide a control method, device, electronic device and storage medium to overcome the problems in the prior art.

[0008] In a first aspect, embodiments of the present disclosure provide a control method for a battery energy storage system, the battery energy storage system comprising multiple battery stacks and an energy storage manager; each battery stack comprising a bidirectional energy storage converter, multiple DC power converters, and multiple battery clusters; each battery cluster being sequentially connected to an AC power grid via the DC power converter and the bidirectional energy storage converter corresponding to the battery cluster; the energy storage manager being signal-connected to each DC power converter and the bidirectional energy storage converter, respectively; the method comprising:

[0009] For each of the battery stacks, the energy storage manager determines a current distribution target ratio set for each battery cluster according to battery cluster parameters of each battery cluster in the battery stack;

[0010] The energy storage manager obtains in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bidirectional energy storage converter;

[0011] The energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the current remaining capacity, and the DC voltage, in accordance with a preset first constraint condition;

[0012] The energy storage manager sends the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated to each bidirectional energy storage converter, and controls each DC power converter based on the current distribution target ratio to adjust the current allocated to each battery cluster.

[0013] In some technical solutions of the present disclosure, the energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the current remaining capacity, and the DC voltage obtained in accordance with a preset first constraint condition; including:

[0014] Based on the power balance principle, the DC active power of the battery stack is calculated according to the first actual AC power, the current remaining capacity, the DC voltage and the first constraint condition;

[0015] The AC active power of each battery stack is calculated based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter.

[0016] In some technical solutions disclosed herein, the above-mentioned first constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference ratio of the battery stack; the reference ratio is the ratio of the DC active power to the DC voltage of the battery stack.

[0017] In some technical solutions of the present disclosure, the DC active power of the battery stack is calculated based on the power balance principle according to the first actual AC power, the current remaining capacity, the DC voltage and the first constraint condition; including:

[0018] Based on a positive correlation between a current remaining capacity of any battery stack and a reference ratio of the battery stack, determining a second relative ratio between the reference ratios of the battery stacks according to the first relative ratios of the current remaining capacities between the battery stacks;

[0019] Based on the power balance principle, the DC active power of each battery stack is calculated according to the second relative ratio between the reference ratios of the battery stacks, the first actual AC power and the DC voltage of each bidirectional energy storage converter.

[0020] In some technical solutions of the present disclosure, the DC active power of each battery stack is calculated based on the power balancing principle according to the second relative ratio between the reference ratios of each battery stack, the first actual AC power, and the DC voltage of each bidirectional energy storage converter, including:

[0021] Based on the power balance principle, a first matrix operation formula is constructed; wherein the second relative ratio between the reference ratios of the battery stacks, the first actual AC power, and the DC voltage of each bidirectional energy storage converter are used as known quantities, and the DC active power of each battery stack is used as a variable to be determined;

[0022] The first matrix operation formula is solved to obtain the DC active power of each battery stack.

[0023] In some technical solutions of the present disclosure, the first matrix operation formula includes a first known matrix, a second known matrix, and a first matrix to be determined; and constructing the first matrix operation formula based on the power balance principle includes:

[0024] constructing the first known matrix according to a second relative ratio between the reference ratios of the battery stacks, a DC voltage and an operating efficiency of each bidirectional energy storage converter;

[0025] constructing the second known matrix according to the first actual AC power;

[0026] constructing the first matrix to be determined according to the DC active power of each of the battery stacks;

[0027] The product of the first known matrix and the first matrix to be determined is equal to the second known matrix.

[0028] In some technical solutions of the present disclosure, the AC active power of each battery stack is calculated based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter, including:

[0029] Determining a conversion ratio corresponding to the DC active power of each bidirectional energy storage converter based on the working efficiency of the bidirectional energy storage converter;

[0030] According to the conversion ratio, the DC active power of the bidirectional energy storage converter is converted into the AC active power of the battery stack.

[0031] In some technical solutions disclosed herein, the power balancing principle is that the total power input of the battery energy storage system is equal to the total power output; the total power input is the first actual AC power of all battery stacks; and the total power output is the sum of the DC active power of each battery stack.

[0032] In some technical solutions of the present disclosure, the energy storage manager obtains the first actual AC power of all battery stacks in the following manner:

[0033] The energy storage manager obtains the sub-AC power of each battery stack;

[0034] Aggregate all the sub-AC powers to obtain the first total power of all battery stacks;

[0035] The first actual AC power is obtained by performing actual loss removal processing on the first total active power.

[0036] In some technical solutions of the present disclosure, the bidirectional energy storage converter is further connected to other energy supply systems;

[0037] The energy storage manager calculates the AC active power of each battery stack in the following manner, including:

[0038] The energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity and the DC voltage in accordance with the preset second constraint condition.

[0039] In some technical solutions of the present disclosure, the energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity, and the DC voltage according to a preset second constraint condition, including:

[0040] Based on the power balance principle, the DC active power of the battery stack is calculated according to the first actual AC power, the second actual AC power, the current remaining capacity, the DC voltage, the DC active power of each other DC energy system, and the second constraint condition;

[0041] The AC active power of each battery stack is calculated based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter.

[0042] In some technical solutions disclosed herein, the above-mentioned second constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference difference of the battery stack; the reference difference is the difference between the first ratio and the second ratio; the first ratio is the ratio of the DC active power to the DC voltage of the battery stack, and the second ratio is the ratio of the DC active power to the DC voltage of other DC energy sources.

[0043] In some technical solutions of the present disclosure, the DC active power of the battery stack is calculated based on the power balance principle according to the first actual AC power, the second actual AC power, the current remaining capacity, the DC voltage, the DC active power of each other DC energy system, and the second constraint, including:

[0044] Based on a positive correlation between the current remaining capacity of the battery stack and the reference difference value of the battery stack, calculating a third relative ratio between the reference difference values ​​of the battery stacks according to the first relative ratio between the current remaining capacity of the battery stacks;

[0045] Based on the power balance principle, the DC active power of each battery stack is calculated according to the third relative ratio, the first actual AC power, the second actual AC power, the DC active power of each other DC energy system and the DC voltage of each bidirectional energy storage converter.

[0046] In some technical solutions of the present disclosure, the DC active power of each battery stack is calculated based on the power balance principle according to the third relative ratio, the first actual AC power, the second actual AC power, the DC active power of each other DC energy system, and the DC voltage of each bidirectional energy storage converter, including:

[0047] Based on the power balance principle, a second matrix operation formula is constructed; wherein the third relative ratio, the first actual AC power, the DC active power of each other DC energy system, and the DC voltage of each bidirectional energy storage converter are used as known quantities, and the DC active power of each battery stack is used as a variable to be determined;

[0048] The second matrix operation formula is solved to obtain the DC active power of each battery stack.

[0049] In some technical solutions of the present disclosure, the second matrix operation formula includes a third known matrix, a fourth known matrix, and a second matrix to be determined; and the second matrix operation formula is constructed based on the power balance principle, including:

[0050] constructing the third known matrix according to a third relative ratio between the reference difference values ​​of the battery stacks, the DC voltage and the operating efficiency of each bidirectional energy storage converter;

[0051] constructing the fourth known matrix according to the first actual AC power, the second actual AC power and the DC active power of each other DC energy system;

[0052] constructing the second matrix to be determined according to the DC active power of each of the battery stacks and the DC active power of each other DC energy system;

[0053] The product of the third known matrix and the second matrix to be determined is equal to a fourth known matrix.

[0054] In some technical solutions of the present disclosure, the AC active power of each battery stack is calculated based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter, including:

[0055] Determining a conversion ratio corresponding to the DC active power of each bidirectional energy storage converter based on the working efficiency of the bidirectional energy storage converter;

[0056] According to the conversion ratio, the DC active power of the bidirectional energy storage converter is converted into the AC active power of the battery stack.

[0057] In some technical solutions disclosed in the present invention, the above-mentioned power balancing principle is that the total power input of the battery energy storage system and other energy power supply systems is equal to the total power output; the total power input is the first actual AC power of all battery stacks and the second actual AC power of other energy power supply systems, and the total power input is the sum of the DC active power of each battery stack and the second actual AC power of other energy power supply systems.

[0058] In some technical solutions disclosed herein, the above-mentioned current distribution target ratio is within the distribution ratio constraint interval, and the battery cluster parameters include at least one of the following items: the current remaining capacity of the battery cluster, the capacity setting critical value, and the distribution ratio constraint interval set for each battery cluster determined based on the total number of battery clusters connected in parallel in the battery energy storage system.

[0059] In some technical solutions of the present disclosure, the allocation ratio constraint interval set for each battery cluster is determined based on the total number of battery clusters in the battery energy storage system, including:

[0060] When system parameters of the battery energy storage system do not satisfy the current sharing condition, an allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters connected in parallel in the battery energy storage system.

[0061] In some technical solutions of the present disclosure, the allocation ratio constraint interval set for each battery cluster is determined based on the total number of battery clusters in the battery energy storage system, including:

[0062] Obtaining a total number of battery clusters in a plurality of battery clusters connected in parallel in the battery energy storage system and an overload constraint ratio of the battery energy storage system, wherein the overload constraint ratio represents a preset ratio at which a current of the battery cluster exceeds a rated current range during charging or discharging;

[0063] According to the overload constraint ratio, an upper limit and a lower limit of an allocation ratio constraint of the battery energy storage system are determined to determine an allocation ratio constraint interval set for each battery cluster.

[0064] In some technical solutions of the present disclosure, the battery cluster parameters include the current remaining capacity of the battery cluster and a capacity setting critical value; wherein the capacity setting critical value represents the fastest convergence of each battery cluster in the battery energy storage system to a consistent state of charge;

[0065] The determining of the current distribution target ratio set for each battery cluster according to the battery cluster parameters includes:

[0066] determining a first current distribution ratio to be adjusted for each battery cluster according to the current remaining capacity of each battery cluster and the capacity setting critical value;

[0067] The current distribution target ratio is determined according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval.

[0068] In some technical solutions disclosed herein, each of the above-mentioned battery clusters corresponds to one of the DC power converters, and each of the battery stacks corresponds to one of the bidirectional energy storage converters; wherein, the battery clusters are packaged together with the DC power converters corresponding to the battery clusters.

[0069] In a second aspect, embodiments of the present disclosure provide a control device for a battery energy storage system, the battery energy storage system comprising a plurality of battery stacks and an energy storage manager; each battery stack comprising a bidirectional energy storage converter, a plurality of DC power converters, and a plurality of battery clusters; each battery cluster being sequentially connected to an AC power grid via the DC power converter and the bidirectional energy storage converter corresponding to the battery cluster; the energy storage manager being signal-connected to each DC power converter and the bidirectional energy storage converter, respectively; the device comprising:

[0070] a determination module, configured to determine, for each of the battery stacks, a current distribution target ratio to be set for each battery cluster according to battery cluster parameters of each battery cluster in the battery stack;

[0071] An acquisition module is used to obtain in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bidirectional energy storage converter;

[0072] a calculation module, configured to calculate the AC active power of each battery stack according to the first actual AC power, the current remaining capacity, and the DC voltage, in accordance with a preset first constraint condition;

[0073] A control module is used to send the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated to each bidirectional energy storage converter, and to control each DC power converter based on the current distribution target ratio to adjust the current allocated to each battery cluster.

[0074] In a third aspect, an embodiment of the present disclosure provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned control method when executing the computer program.

[0075] In a fourth aspect, an embodiment of the present disclosure provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned control method are executed.

[0076] The technical solutions provided by the embodiments of the present disclosure may have the following beneficial effects:

[0077] The method disclosed herein includes, for each of the battery stacks, the energy storage manager determining a current distribution target ratio set for each battery cluster based on the battery cluster parameters of each battery cluster in the battery stack; the energy storage manager obtaining in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks and the DC voltage of each bidirectional energy storage converter; the energy storage manager calculating the AC active power of each of the battery stacks according to a preset first constraint condition based on the first actual AC power, the current remaining capacity and the DC voltage; the energy storage manager sending the AC active power to the corresponding bidirectional energy storage converter to adjust the current distributed to each of the bidirectional energy storage converters, and controlling each of the DC power converters based on the current distribution target ratio to adjust the current distributed to each battery cluster.

[0078] The present disclosure controls the AC active power given to the bidirectional energy storage converter, thereby controlling the current of each DC bus, so that each battery stack can be fully charged or fully discharged at the same time. On the other hand, it also distributes the current ratio of battery clusters in the same stack to reduce system differences, greatly improving the consistency, lifespan, working efficiency and charge and discharge depth of the entire battery energy storage system.

[0079] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0081] FIG1 shows a flow chart of a control method provided by an embodiment of the present disclosure;

[0082] FIG2 shows a schematic diagram of a battery energy storage system provided by an embodiment of the present disclosure;

[0083] FIG3 shows a schematic diagram of another battery energy storage system provided by an embodiment of the present disclosure;

[0084] FIG4 shows a schematic diagram of a circuit connection of a battery energy storage system and other energy systems provided by an embodiment of the present disclosure;

[0085] FIG5 shows a schematic diagram of a circuit connection between a battery energy storage system and other energy systems provided by an embodiment of the present disclosure;

[0086] FIG6 is a schematic diagram of a control device provided by an embodiment of the present disclosure;

[0087] FIG7 is a schematic structural diagram of an electronic device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0088] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. It should be understood that the drawings in the present disclosure are only for the purpose of illustration and description and are not used to limit the scope of protection of the present disclosure. In addition, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in the present disclosure illustrate operations implemented according to some embodiments of the present disclosure. It should be understood that the operations of the flowchart can be implemented out of sequence, and steps that do not have a logical context relationship can be reversed in order or implemented simultaneously. In addition, those skilled in the art, guided by the contents of the present disclosure, can add one or more other operations to the flowchart, or remove one or more operations from the flowchart.

[0089] In addition, the described embodiments are only a portion of the embodiments of the present disclosure, rather than all of the embodiments. The components of the embodiments of the present disclosure generally described and shown in the drawings herein can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the disclosure claimed for protection, but merely represents selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present disclosure.

[0090] It should be noted that the term “comprising” will be used in the embodiments of the present disclosure to indicate the existence of the features claimed thereafter, but does not exclude the addition of other features.

[0091] The power of a single battery cluster is no longer sufficient to meet human needs. To meet people's ever-increasing power demands, battery energy storage systems have emerged. A battery energy storage system consists of multiple battery stacks connected in parallel, each of which is composed of multiple battery clusters connected in parallel. To extend the life of a battery energy storage system, it is necessary to ensure that the remaining charge in each battery cluster remains at the same level during use (charging and discharging).

[0092] Existing technologies distribute current among battery clusters based on their capacity ratios. This method of distribution has poor accuracy, and during use, some battery stacks may reach full charge or full discharge before others, causing them to exit the operating state at different times than other battery stacks, affecting the utilization rate and depth of discharge (DoD) of the entire energy storage system.

[0093] Based on this, the embodiments of the present disclosure provide a control method, device, electronic device, and storage medium, which are described below through embodiments.

[0094] FIG1 shows a flow chart of a control method provided by an embodiment of the present disclosure, which acts on a battery energy storage system. The method includes S101 to S104. Specifically:

[0095] S101. For each battery stack, the energy storage manager determines, according to battery cluster parameters of each battery cluster in the battery stack, a current distribution target ratio to be set for each battery cluster;

[0096] S102, the energy storage manager obtains in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bidirectional energy storage converter;

[0097] S103: The energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the current remaining capacity, and the DC voltage, in accordance with a preset first constraint condition;

[0098] S104. The energy storage manager sends the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated to each bidirectional energy storage converter, and controls each DC power converter based on the current distribution target ratio to adjust the current allocated to each battery cluster.

[0099] The present disclosure controls the AC active power given to the bidirectional energy storage converter, thereby controlling the current of each DC bus, so that each battery stack can be fully charged or fully discharged at the same time. On the other hand, it also distributes the current ratio of battery clusters in the same stack to reduce system differences, greatly improving the consistency, lifespan, working efficiency and charge and discharge depth of the entire battery energy storage system.

[0100] The following describes some embodiments of the present disclosure in detail. In the absence of conflict, the following embodiments and features thereof may be combined with each other.

[0101] Before introducing the control method disclosed herein, let's first introduce the battery energy storage system in the disclosed embodiment. Prior art battery energy storage systems consist simply of multiple battery clusters connected in parallel, without a DC / DC converter. Traditional energy storage systems typically directly connect multiple battery clusters in parallel to the DC side of a PCS. This approach can lead to inter-cluster currents due to inter-cluster voltage differences caused by inconsistencies between battery clusters. Excessive inter-cluster currents can affect battery life. Furthermore, due to the inconsistency of internal resistance, the current in each battery cluster during the charge and discharge process is determined by the internal resistance, which further amplifies the reduced depth of discharge caused by the "barrel effect." Adding a DC-DC converter allows for precise control of the current in each cluster, enhancing system consistency and increasing depth of discharge. Unlike parallel DC-DC converters, series DC-CDC converters have lower voltage requirements, a constant charge and discharge current range, and an output voltage of only tens of volts. Compared to the hundreds or thousands of volts of parallel DC-CDC converters, they offer low power, a small size, and low cost.

[0102] The PCS control algorithm includes PQ control (P active power, Q reactive power, which is the power control mode of PCS), VF control (V voltage amplitude, F voltage frequency, which is the constant voltage control mode of PCS) and droop control. The distribution algorithm described in the control method of the present invention is applicable to the PCS grid-connected PQ control algorithm.

[0103] As shown in Figure 2, the battery energy storage system in the disclosed embodiment includes multiple battery stacks and an energy storage manager. Each battery stack includes a bidirectional energy storage converter, multiple DC power converters, and multiple battery clusters. Each battery cluster is sequentially connected to the AC power grid through the DC power converter and bidirectional energy storage converter corresponding to the battery cluster. The energy storage manager is signal-connected to each DC power converter and bidirectional energy storage converter. Each battery cluster corresponds to a DC power converter, and each battery stack corresponds to a bidirectional energy storage converter. The battery clusters are packaged together with the DC power converters corresponding to the battery clusters. In an optional embodiment, as shown in Figure 3, the energy storage manager in the disclosed embodiment includes a battery management system (BMS) and an energy management system (EMS). In this embodiment, the BMS and EMS jointly assume the management responsibilities of the energy storage manager in the above-mentioned embodiment. It should be noted that in Figures 2 and 3, solid connecting lines represent electrical connections, and interspersed connecting lines represent signal connections. The dashed boxes outside battery clusters 1 to 3 indicate that battery clusters 1 to 3 (including the DC / DCs corresponding to battery clusters 1 to 3) are encapsulated in a single housing. The dashed boxes outside the DC / DCs in the figure merely delineate all DC / DCs as a single unit and do not represent physical positional relationships. In the system shown in FIG3 , conventional control methods are unable to directly control the DC current of each energy storage PCS through EMS instructions. Furthermore, the efficiency of each PCS and the DC side voltage differ due to the inconsistency of the battery clusters. Each DC bus current is independent and uncoupled. Directly distributing the total power based on the capacity proportion of each battery stack makes it difficult to accurately control the DC bus current. Consequently, when the energy storage system is connected to the grid, a certain energy storage battery stack or container may reach a fully charged or fully discharged state first, causing the stack to exit operation, impacting the availability and DOD of the entire energy storage system.

[0104] For the system shown in Figure 2, the control method in steps S101 to S104 can be divided into two levels of control. The first level involves the energy storage manager's control of the DC / DC side. Specifically, for each battery stack, the energy storage manager determines a target current distribution ratio for each battery cluster based on the battery cluster parameters of each battery cluster in the battery stack. Based on the target current distribution ratio, the energy storage manager controls each DC power converter to adjust the current allocated to each battery cluster. The second level involves the energy storage manager's control of the PCS side. Specifically, the energy storage manager obtains in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bidirectional energy storage converter. The energy storage manager calculates the AC active power of each battery stack based on the obtained first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint. The energy storage manager then distributes the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated to each bidirectional energy storage converter.

[0105] For the system shown in Figure 3, the control method from S101 to S104 can be divided into two levels of control. The first level is the BMS's control of the DC / DC side, specifically: for each battery stack, the BMS determines a target current distribution ratio for each battery cluster based on the battery cluster parameters of each battery cluster in the battery stack; based on the target current distribution ratio, it controls each DC power converter to adjust the current allocated to each battery cluster. The second level is the EMS's control of the PCS side, specifically: the EMS obtains the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bidirectional energy storage converter in real time; the EMS calculates the AC active power of each battery stack based on the obtained first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint; and the EMS transmits the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated to each bidirectional energy storage converter.

[0106] In specific implementation, EMS is set up in multiple levels in each battery stack (for example, it can be set up in the form of battery pack, battery cluster and battery stack). The battery pack power data is obtained from each battery pack at the lower level, and then summarized to obtain the sub-AC power of each battery stack. All the sub-AC powers are aggregated together to obtain the first total power (P0) of all battery stacks; the first actual AC power (P0) is obtained by performing actual loss removal on the first total power. * ). P* is the AC side power of the entire energy storage system. The specific actual loss reduction process is manually input according to demand, or it can be based on the optimization algorithm (taking into account the income, battery health, temperature, etc.), but it follows P* ≤P0. After obtaining the first actual AC power, the BMS sends the first actual AC power to the EMS.

[0107] It should be noted that, in the processing of the above two levels, there is no sequential processing order between the first level and the second level, that is, S101 to S104 in the embodiment of the present disclosure are merely exemplary, and can also be performed in the manner of S102, S103, S101, S104, or in the manner of S101, S102, S103 being performed simultaneously followed by S104.

[0108] The control method of the present disclosure is introduced below in two levels. Before introducing the control method, the characters appearing below are defined. Specifically, i: battery stack number; j: battery cluster number; imax: number of PCS in parallel; jmax: number of battery clusters in parallel in each battery stack; P ij : The power of the jth battery cluster corresponding to the i-th PCS; P DC,i : DC side power of the i-th PCS; P DG : Power of other energy supply system per stack; P AC,i : AC active power sent by EMS to the i-th PCS; soc0: initial soc of battery cluster; Δsoc0: maximum soc difference between initial clusters; I ij,pct : Current ratio of the jth cluster in the i-th stack; Cap ij : The current remaining capacity (chargeable / dischargeable) of the jth cluster in the i-th stack; C i,min : The remaining working capacity when the system SOC converges to the same level as the DC / DC fast allocation algorithm; I ij : DC current value of the jth cluster of the i-th pile; I DC,i : DC bus current of the i-th stack; η i : The working efficiency of the i-th PCS; Cap i : The current remaining capacity of the i-th battery (chargeable / dischargeable); U DC,i : DC voltage of the DC busbar of the i-th stack; A: coefficient matrix of the boundary condition equation system; x: vector of variables to be solved of the boundary condition equation system; b: constraint condition of the boundary condition equation system; I Bat : Total current of each DC bus battery; I DG : Current of other energy supply system of each DC bus.

[0109] In an optional embodiment, the current distribution target ratio is determined for the first level:

[0110] In S101, the battery cluster parameter refers to a parameter associated with the current distribution of the battery cluster, which may be an attribute characteristic of the battery cluster, such as the current remaining capacity of the battery cluster; the parameter may be a numerical value pre-set according to the attribute characteristics of the battery cluster, wherein the preset numerical value may be adjusted in real time and the numerical value is applicable to each battery cluster, such as each battery cluster corresponds to the same capacity setting critical value; the parameter may also be a numerical value calculated according to the attribute characteristics of the battery cluster, such as an allocation ratio constraint interval calculated according to the total number of battery clusters and the overload constraint ratio.

[0111] Here, the target current distribution ratio for each battery cluster is determined based on the battery cluster parameters, and this current distribution ratio is within the distribution ratio constraint interval. In other words, the target current distribution ratio for each battery cluster can be accurately determined based on the battery cluster parameters. By distributing current to each battery cluster according to this current distribution ratio, battery clusters of different capacities can achieve balance as quickly as possible during operation.

[0112] The above allocation ratio constraint interval is obtained through the following steps:

[0113] S1011. Obtain a total number of battery clusters in a plurality of battery clusters connected in parallel in a battery energy storage system and an overload constraint ratio of the battery energy storage system. The overload constraint ratio represents a preset ratio by which a current of the battery cluster exceeds a rated current range during charging or discharging.

[0114] Here, overload means that the battery energy storage system can still operate beyond the rated current range under certain abnormal conditions. Among them, the abnormal state refers to the state in which the battery energy storage system operates without a cluster but maintains a constant power / current output. The overload constraint ratio represents the preset proportion by which the current of the battery cluster exceeds the rated current range during charging or discharging. In other words, the overload constraint ratio represents the preset proportion by which the current of the battery cluster during charging is allowed to exceed the first current specified value or the preset proportion by which the current of the battery cluster during discharging is allowed to be lower than the second current specified value, wherein the second current specified value is less than the first current specified value, and the range between the first current specified value and the second current specified value constitutes the rated current range.

[0115] Exemplarily, the range of the overload constraint ratio is between 0 and 1. Specifically, the overload constraint ratio may be 0.1.

[0116] S1012: Determine an upper limit and a lower limit of an allocation ratio constraint of the battery energy storage system according to the overload constraint ratio, so as to determine an allocation ratio constraint interval to be set for each battery cluster.

[0117] Specifically, the allocation ratio constraint upper limit and the allocation ratio constraint lower limit are determined as two endpoint values ​​of the allocation ratio constraint interval.

[0118] Exemplarily, S1012 specifically includes:

[0119] S1012a. Determine the total upper limit value and the total lower limit value of the allocation ratio constraint of the battery energy storage system according to the overload constraint ratio.

[0120] Here, since the overload constraint ratio is between 0 and 1, the total value of the upper limit of the allocation ratio constraint is the sum of 1 and the overload constraint ratio, and the total value of the lower limit of the allocation ratio constraint is the difference between 1 and the overload constraint ratio.

[0121] S1012b: Determine the upper and lower limits of the allocation ratio constraints to be set for each battery cluster by using the ratios of the total values ​​of the upper and lower limits of the allocation ratio constraints to the total number of battery clusters.

[0122] Here, the allocation ratio constraint interval of each battery cluster is the same.

[0123] For example, the total number of battery clusters is defined as n, the overload constraint ratio is defined as limit, and I pct_max represents the upper limit of the allocation ratio constraint, I pct_min Indicates the lower limit of the allocation ratio constraint; the upper limit of the allocation ratio constraint I pct_max and the lower limit of the allocation ratio constraint I pct_min The calculation formula is as follows:

[0124] For example, according to the actual configuration parameters of the battery cluster, the limit can be set to 0.1.

[0125] The disclosed embodiments can adjust the overload constraint ratio in real time according to the actual operating conditions of the battery cluster, thereby flexibly setting the upper and lower limits of the allocation ratio constraint. Within the allocation ratio constraint range, current can be allocated according to the current allocation target ratio set for each battery cluster. Since the range of the current allocation target ratio is locked, the stability and reliability of the battery energy storage system can be further improved.

[0126] Furthermore, when the state of charge of each battery cluster differs greatly, the current distribution target ratios of each battery cluster are different, but the differences in the current distribution target ratios are guaranteed to be within the distribution ratio constraint range, so that the state of charge of each battery cluster can be consistent at a relatively fast speed while avoiding the problem of overload of the battery energy storage system due to external oscillation to the greatest extent. This can achieve balanced management and safe use, and further extend the service life of the battery clusters in the battery energy storage system.

[0127] In a preferred embodiment, the battery cluster parameters include the current remaining capacity of the battery cluster and a capacity setting critical value; here, the current remaining capacity refers to the maximum chargeable or dischargeable capacity of the battery cluster in the current working state, and the capacity setting critical value represents the fastest convergence of each battery cluster in the battery energy storage system to a consistent state of charge. Exemplarily, the capacity setting critical value can be the minimum value among the current remaining capacities of multiple battery clusters.

[0128] Here, a capacity adjustment limit range is pre-set for the capacity setting critical value. When adjusting the capacity setting critical value, the capacity adjustment limit range cannot be exceeded. Specifically, when multiple battery clusters in the battery energy storage system are in a discharging condition or a charging condition, the capacity adjustment limit range corresponds to the range between 0 and the capacity setting critical value.

[0129] The current distribution target ratio set for each battery cluster according to the battery cluster parameters specifically includes:

[0130] Step 1021 : Determine a first current distribution ratio to be adjusted for each battery cluster according to the current remaining capacity and the capacity setting threshold of each battery cluster.

[0131] Specifically, the capacity difference between the current remaining capacity of each battery cluster and the capacity setting critical value is calculated, the sum of the capacity differences corresponding to all battery clusters is calculated, and for each battery cluster, the ratio between the capacity difference corresponding to the battery cluster and the sum of the capacity differences is calculated, and the ratio is determined as the first current distribution ratio to be adjusted.

[0132] For example, the first current distribution ratio to be adjusted of the i-th battery cluster is defined as I 1i,pct , the capacity setting critical value is min_cap, and the current remaining capacity is cap i , the total number of battery clusters is n; furthermore, the first current distribution ratio to be adjusted for the i-th battery cluster is I 1i,pct The calculation formula is as follows:

[0133] By using the above formula, the first current distribution ratio to be adjusted corresponding to each battery cluster can be calculated. According to the first current distribution ratio to be adjusted, the purpose of quickly distributing current to the battery cluster can be achieved.

[0134] Step 1022: Determine a current distribution target ratio based on whether the first current distribution ratio to be adjusted is within a distribution ratio constraint interval.

[0135] Step 1022 specifically includes:

[0136] Step 1022a: If it is detected that the first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, determine the first current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval as the corresponding current distribution target ratio for each battery cluster.

[0137] Here, if the first current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint range, the currently calculated first current distribution ratio to be adjusted can be determined as the current distribution target ratio to distribute current to the battery cluster according to the first current distribution ratio to be adjusted.

[0138] Step 1022b: If it is detected that the first current distribution ratio to be adjusted set for the battery cluster is not within the distribution ratio constraint interval, the capacity setting critical value is adjusted, and the first current distribution ratio to be adjusted set for each battery cluster is re-determined based on the current remaining capacity of each battery cluster and the adjusted capacity setting critical value, until the first current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, and the first current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval is determined to be the corresponding current distribution target ratio of each battery cluster.

[0139] That is, when it is detected that the first current distribution ratio to be adjusted corresponding to a battery cluster is not within the distribution ratio constraint interval, the capacity setting threshold value may be adjusted. For example, the capacity setting threshold value may be reduced, and then the first current distribution ratio to be adjusted set for each battery cluster is recalculated according to the calculation formula for the first current distribution ratio to be adjusted in step 1021 until the capacity setting threshold value is adjusted to the minimum value of the capacity adjustment limit range, such as the minimum value of the capacity adjustment limit range being 0. If, under the condition that the capacity setting threshold value is within the capacity adjustment limit range, it is detected that the first current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint interval, then the currently determined first current distribution ratio to be adjusted may be determined as the current distribution target ratio.

[0140] Step 1023: If it is detected that the adjusted capacity setting critical value is not within the capacity adjustment limit range, and the first current distribution ratio to be adjusted that is newly set for the battery cluster is not within the distribution ratio constraint interval, then a second current distribution ratio to be adjusted that is set for each battery cluster is determined based on the current remaining capacity of each battery cluster;

[0141] Here, the current remaining capacities of all battery clusters are summed to obtain the current remaining capacity sum value. For each battery cluster, the ratio between the current remaining capacity corresponding to the battery cluster and the current remaining capacity sum value is calculated, and the ratio is determined as the second current distribution ratio to be adjusted.

[0142] For example, the second current distribution ratio to be adjusted of the i-th battery cluster is defined as I 2i,pct , and then, the second current distribution ratio to be adjusted for the i-th battery cluster is I 2i,pct The calculation formula is as follows:

[0143] The second current distribution ratio to be adjusted corresponding to each battery cluster can be calculated by the above formula. The purpose of quickly distributing current to the battery cluster can be achieved according to the second current distribution ratio to be adjusted.

[0144] Step 1024 : Determine the current distribution target ratio according to whether the second current distribution ratio to be adjusted is within the distribution ratio constraint interval.

[0145] Step 1024 specifically includes:

[0146] Step 1024a: If it is detected that the second current distribution ratio to be adjusted set for each battery cluster is within the distribution ratio constraint interval, determine the second current distribution ratio to be adjusted for each battery cluster within the distribution ratio constraint interval as the corresponding current distribution target ratio for each battery cluster.

[0147] Here, if the second current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint range, the currently calculated second current distribution ratio to be adjusted can be determined as the current distribution target ratio to distribute current to the battery cluster according to the second current distribution ratio to be adjusted.

[0148] Step 1024b: If it is detected that the second current distribution ratio to be adjusted set for the battery cluster is not within the distribution ratio constraint interval, the number of first battery clusters corresponding to the battery clusters whose second current distribution ratio to be adjusted is greater than the upper limit of the distribution ratio constraint and the number of second battery clusters corresponding to the battery clusters whose second current distribution ratio to be adjusted is less than the lower limit of the distribution ratio constraint are determined respectively.

[0149] The battery cluster parameters include an allocation ratio constraint interval, which includes an allocation ratio constraint upper limit and an allocation ratio constraint lower limit. The number of the first battery cluster can be determined based on the allocation ratio constraint upper limit, and the number of the second battery cluster can be determined based on the allocation ratio constraint lower limit.

[0150] Step 1024c: Determine the allocation ratio adjustment value of the second current allocation ratio to be adjusted that is not within the allocation ratio constraint interval to the closest allocation ratio constraint upper limit or allocation ratio constraint lower limit, so as to obtain the total allocation ratio adjustment value corresponding to all battery clusters whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval.

[0151] Among them, the allocation ratio adjustment value obtained by adjusting the second current allocation ratio to be adjusted, which is less than the lower limit of the allocation ratio constraint, to the lower limit of the allocation ratio constraint is a negative value, and the allocation ratio adjustment value obtained by adjusting the second current allocation ratio to be adjusted, which is greater than the upper limit of the allocation ratio constraint, to the upper limit of the allocation ratio constraint is a positive value.

[0152] Here, the difference between the second current distribution ratio to be adjusted and the closest upper or lower distribution ratio constraint is calculated; this difference is the distribution ratio adjustment value. Specifically, this difference can be positive or negative. Subtracting the second current distribution ratio to be adjusted from the lower distribution ratio constraint, which is less than the lower distribution ratio constraint, results in a negative distribution ratio adjustment value; while subtracting the second current distribution ratio to be adjusted from the upper distribution ratio constraint, which is greater than the upper distribution ratio constraint, results in a positive distribution ratio adjustment value. The distribution ratio adjustment values ​​corresponding to all battery clusters whose second current distribution ratios to be adjusted are not within the distribution ratio constraint interval are summed to obtain a total distribution ratio adjustment value. Here, since distribution ratio adjustment values ​​can be both positive and negative, the calculated total distribution ratio adjustment value can be either positive or negative.

[0153] Step 1025 : Determine the current distribution target ratio according to the relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold.

[0154] Step 1025 specifically includes:

[0155] Step 1025a: If the total value of the allocation ratio adjustment is less than or equal to the preset allocation ratio adjustment threshold, then the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval according to the allocation ratio constraint lower limit, the total value of the allocation ratio adjustment, and the number of the second battery clusters; and the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery cluster.

[0156] For example, the preset distribution ratio adjustment threshold may be 0. If, for the second current distribution ratios to be adjusted corresponding to the battery clusters calculated in step 1023, the second current distribution ratios to be adjusted corresponding to some or all of the battery clusters are not within the distribution ratio constraint interval, then the new calculation method involved in step 1025 is used to calculate the current distribution target ratio for the battery clusters whose second current distribution ratios to be adjusted are not within the distribution ratio constraint interval, while the calculation method involved in step 1023 is continued to be used to calculate the current distribution target ratio for the battery clusters whose second current distribution ratios to be adjusted are within the distribution ratio constraint interval.

[0157] Here, if the total value of the distribution ratio adjustment is less than or equal to the preset distribution ratio adjustment threshold, then for the battery cluster whose second current distribution ratio to be adjusted is not within the distribution ratio constraint interval, the current distribution target ratio is determined using the following calculation method:

[0158] The ratio between the total value of the allocation ratio adjustment and the number of the second battery clusters is used to determine the allocation ratio adjustment mean; and the sum of the allocation ratio constraint lower limit and the allocation ratio adjustment mean is used to determine the current allocation target ratio to be set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval.

[0159] For example, the current distribution target ratio of the i-th battery cluster is defined as I 32i,pct , the number of the second battery cluster is n2, the total value of the allocation ratio adjustment is Vol, and then, the current allocation target ratio of the i-th battery cluster is I 32i,pct The calculation formula is as follows:

[0160] Step 1025b: If the total value of the allocation ratio adjustment is less than or equal to the preset allocation ratio adjustment threshold, then the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval according to the allocation ratio constraint upper limit, the total value of the allocation ratio adjustment, and the number of the first battery clusters, and the current allocation target ratio is set for the battery cluster whose second current allocation ratio to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery cluster.

[0161] Here, if the total value of the distribution ratio adjustment is less than or equal to the preset distribution ratio adjustment threshold, then for the battery cluster whose second current distribution ratio to be adjusted is not within the distribution ratio constraint interval, the current distribution target ratio is determined using the following calculation method:

[0162] The ratio between the total value of the allocation ratio adjustment and the number of the first battery clusters is used to determine the allocation ratio adjustment mean value; and the sum of the allocation ratio constraint upper limit and the allocation ratio adjustment mean value is used to determine the current allocation target ratio to be set for the battery cluster whose second current allocation ratio to be adjusted is not within the allocation ratio constraint interval.

[0163] For example, the current distribution target ratio of the i-th battery cluster is defined as I 31i,pct The number of the first battery cluster is n1, the total value of the allocation ratio adjustment is Vol, and then the current allocation target ratio of the i-th battery cluster is I 31i,pct The calculation formula is as follows:

[0164] It should be noted that when the second current distribution ratio to be adjusted is not within the distribution ratio constraint interval, the current distribution target ratio is directly calculated through step 1025a or step 1025b according to the size relationship between the total distribution ratio adjustment value and the preset distribution ratio adjustment threshold.

[0165] Step 1025c: if it is detected that the current distribution target ratio set for the battery cluster whose second current distribution ratio to be adjusted is not within the distribution ratio constraint interval is not within the distribution ratio constraint interval, recalculate the total distribution ratio adjustment value corresponding to all battery clusters whose current distribution target ratio is not within the distribution ratio constraint interval;

[0166] Detect the size relationship between the recalculated total value of the allocation ratio adjustment and the preset allocation ratio adjustment threshold, and loop through step 1025a and / or step 1025b until a new current allocation target ratio is set for each battery cluster whose current allocation target ratio is not within the allocation ratio constraint interval and is within the allocation ratio constraint interval.

[0167] The current distribution target ratio finally obtained in step 1025c can be guaranteed to be within the distribution ratio constraint range, and no further calculation is required through other methods.

[0168] Through the above method, different calculation methods can be used to determine the current distribution target ratio under different parameter conditions, so that the current can be accurately distributed to each battery cluster according to the current distribution target ratio, thereby enabling battery clusters of different capacities to reach balance as quickly as possible during operation.

[0169] In the embodiment of the present disclosure, the system parameters of the battery energy storage system may not meet the current sharing conditions. In this case, the following steps are performed:

[0170] S201: If system parameters of the battery energy storage system do not satisfy a current sharing condition, determine an allocation ratio constraint interval set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system;

[0171] S202, determining a current distribution target ratio to be set for each battery cluster based on battery cluster parameters; wherein the current distribution target ratio is within a distribution ratio constraint interval, and the battery cluster parameters include at least one of the following items: a current remaining capacity of the battery cluster, a capacity setting threshold, and a distribution ratio constraint interval; and distributing current to each battery cluster according to the current distribution target ratio;

[0172] S203 : When the system parameters of the battery energy storage system meet the current sharing condition, determine the current sharing ratio set for each battery cluster according to the total number of battery clusters; and distribute current to each battery cluster according to the current sharing ratio.

[0173] The description of S202 may refer to the above embodiment and will not be repeated here.

[0174] In S201, the current sharing condition includes one of the following items: the battery energy storage system is in a static operating condition, the DC converter in the battery energy storage system is in a fault state, the minimum state of charge of the battery energy storage system during discharge is not greater than a first preset ratio, the maximum state of charge of the battery energy storage system during charging is not less than a second preset ratio, the first preset ratio is less than the second preset ratio, and the state of charge difference is less than a preset difference threshold, where the state of charge difference represents the difference between the maximum state of charge and the minimum state of charge of all battery clusters currently connected to the DC bus.

[0175] The battery management system (BMS) collects statistics on the total number of battery clusters connected in parallel, the initial state of charge of each battery cluster, the current remaining capacity of each battery cluster, and system operating conditions. System operating conditions include static conditions, charging conditions, and discharging conditions. The BMS uses this data to determine whether the battery energy storage system parameters meet the current sharing requirements.

[0176] For example, in order to prevent excessive differences in the current remaining capacities of the battery clusters in the battery energy storage system, the preset difference threshold is selected to be a relatively small value, such as 1%.

[0177] Here, if the system parameters of the battery energy storage system do not meet the above-mentioned current sharing conditions, the allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters in the battery energy storage system. The specific implementation method can be referred to S101 and will not be repeated here.

[0178] Furthermore, in S203 , when the system parameters of the battery energy storage system meet the current sharing condition, the current sharing ratio set for each battery cluster is determined according to the total number of battery clusters; and current is distributed to each battery cluster according to the current sharing ratio.

[0179] That is to say, when the battery energy storage system is in a static operating condition, the DC converter in the battery energy storage system is in a faulty state, the minimum state of charge of the battery energy storage system during discharge is not greater than a first preset ratio, and the maximum state of charge of the battery energy storage system during charging is not less than a second preset ratio, the first preset ratio is less than the second preset ratio. For example, the first preset ratio is 10%, the second preset ratio is 90%, and the state of charge difference is less than a preset difference threshold. The state of charge difference represents the difference between the maximum state of charge and the minimum state of charge of all battery clusters currently connected to the DC bus. The current sharing ratio set for each battery cluster is directly determined based on the total number of battery clusters.

[0180] Exemplarily, the current sharing ratio is determined by the following formula:

[0181] Where n represents the total number of battery clusters.

[0182] By determining the current sharing ratio set for each battery cluster in the above manner, it is possible to quickly distribute current to each battery cluster, which is relatively simple and convenient.

[0183] The disclosed embodiment first defines a distribution ratio constraint interval set for each battery cluster. This allows the current distribution target ratio set for each battery cluster to be controlled within the distribution ratio constraint interval, regardless of whether the initial states of charge of the battery clusters differ significantly. This prevents excessive differences in the current distribution target ratios of the battery clusters when the initial states of charge differ significantly. This not only allows the battery clusters to reach a consistent state of charge quickly, but also prevents oscillations caused by external factors of the battery energy storage system, which can easily cause overload of the battery energy storage system when the current distribution ratios differ significantly. The current distribution target ratio set for each battery cluster is then determined based on battery cluster parameters, which include at least one of the following: the current remaining capacity of the battery cluster, a capacity setting threshold, and the distribution ratio constraint interval. The DC converter in the battery energy storage system can accurately distribute current to each battery cluster according to the current distribution target ratio in this manner. The current distribution target ratio can be configured as a limit ratio within the distribution ratio constraint interval, allowing the DC converter to charge and discharge at an allowable limit current. This ensures that battery clusters of different capacities quickly reach equilibrium during operation, thereby increasing the stability and reliability of the battery energy storage system.

[0184] In an optional embodiment, the AC active power of each battery stack is calculated for the second level: In order to calculate the AC active power of each battery stack, the embodiment of the present disclosure first calculates the DC active power of each battery stack, and then converts the active power to obtain the AC active power of the battery stack.

[0185] When calculating the DC active power of a battery stack, the disclosed embodiment is primarily based on a preset first constraint. This first constraint is that the current remaining capacity of any battery stack is positively correlated with a reference ratio for that battery stack; the reference ratio is the ratio of the DC active power of the battery stack to the DC voltage.

[0186] The current remaining capacity of the battery stack is the sum of the current remaining capacities of each battery cluster in the battery stack, which can be calculated as follows:

[0187] During specific implementation, the reference ratio in the embodiment of the present disclosure can be expressed using the DC bus current, that is, the DC bus current is the ratio of DC active power to DC voltage. Furthermore, the current remaining capacity of any battery stack in the embodiment of the present disclosure is positively correlated with the DC bus current of the battery stack. Based on the positive correlation between the current remaining capacity of any battery stack and the DC bus current of the battery stack, the current remaining capacity of each battery stack is obtained in the embodiment of the present disclosure, and the relative ratio between the DC bus currents can be obtained by the relative ratio between the current remaining margins. In order to distinguish, the embodiment of the present disclosure refers to the relative ratio of the current remaining capacity between each of the battery stacks as the first relative ratio, and the relative ratio between the reference ratios (i.e., DC bus currents) of each battery stack as the second relative ratio. Specifically: I DC,1 :I DC,2 :…:I DC,i =Cap1:Cap2:…:Cap i

[0188] The positive correlation between the current remaining capacity of any battery stack and the DC bus current of that battery stack in the disclosed embodiments is determined by the connection relationship of the battery energy storage system in the disclosed embodiments. In the battery energy storage system in the disclosed embodiments, each battery stack is independent and has its own independent thermal management system. Therefore, only the simultaneous full charge or discharge of different battery stacks in parallel operation is considered. Excessive differences in DC bus current within the maximum power allowable range will not affect battery consistency. To achieve simultaneous full charge or discharge of the battery stacks, the DC bus current ratio is determined by capacity.

[0189] After determining the second relative ratio between the DC bus currents of each battery stack, and combining the DC voltage obtained in the embodiment of the present disclosure with the DC voltage of each battery stack and the second relative ratio of the battery stack, the ratio between the DC active powers of each battery stack can be calculated. In combination with the power balance principle (the total power input of the battery energy storage system is equal to the total power output; the total power input is the first actual AC power of all battery stacks; the total power output is the sum of the DC active powers of each battery stack), the first actual AC power is distributed to each battery stack according to the second relative ratio to obtain the DC active power of each battery stack. After obtaining the DC active power of each battery stack, the DC active power is converted to obtain the AC active power of the battery stack.

[0190] In an optional embodiment, due to factors such as loss of electrical energy during use, in order to improve accuracy, the disclosed embodiment also needs to consider the actual working efficiency of the PCS. That is, when calculating the DC active power based on the power balance principle, the total power input here is the first actual AC power of all battery stacks; the total power output here is the DC active power (P) of each battery stack at the actual working efficiency.AC,i Multiply by η i When converting DC active power, it is also necessary to consider the actual working efficiency of the PCS and make the conversion based on the working efficiency.

[0191] To improve the efficiency of calculating DC active power, the disclosed embodiment employs a matrix operation formula. Specifically, the second relative ratio between the reference ratios of the battery stacks, the first actual AC power, and the DC voltage of each bidirectional energy storage converter are used as known quantities, and the DC active power of each battery stack is used as the variable to be determined. Based on the principle of power balance, a first matrix operation formula is constructed; the DC active power of each battery stack is obtained by solving the first matrix operation formula.

[0192] The constructed first matrix operation formula is specifically: the product of the first known matrix and the first matrix to be determined is equal to the second known matrix. The first known matrix is ​​constructed based on the second relative ratio between the reference ratios of the battery stacks, the DC voltage, and the operating efficiency of each bidirectional energy storage converter; the second known matrix is ​​constructed based on the first actual AC power; and the first matrix to be determined is constructed based on the DC active power of each battery stack.

[0193] In specific implementation, the maximum power PO of the battery system is first obtained through BMS collection and conversion, specifically:

[0194] The actual charging and discharging operating power P* of the energy storage battery system needs to be set manually or obtained by grid dispatch instructions or optimization algorithms, but must meet the following requirements: P * ≤P0

[0195] The power balancing principle in this embodiment can be expressed as:

[0196] The first matrix operation formula constructed based on the power balance principle is: A*x=b; specifically:

[0197] Among them, the variable to be determined is: x = A -1 *b. By solving for x, the AC active power of each battery stack can be obtained.

[0198] The conversion of the AC active power of each battery stack can be performed in the following manner:

[0199] In an optional embodiment, the battery energy storage system in the embodiment of the present disclosure may also be AC-coupled with other energy supply systems, and the connection method is shown in Figure 4. The other energy supply systems are connected in parallel on the AC side of the PCS. The battery energy storage system in the embodiment of the present disclosure may also be DC-coupled with other energy supply systems, and the connection method is shown in Figure 5: each other energy supply system is individually connected in parallel to each DC bus, and then inverted to the AC side by the PCS. Therefore, the efficiency corresponding to each DC energy supply system should be consistent with the AC-DC conversion efficiency of the energy storage system, which is determined by the PCS. In view of this situation, when calculating the AC active power of each battery stack, the embodiment of the present disclosure needs to exclude the DC current of other energy supply systems. The biggest difference between it and the above embodiment lies in the constraints and consideration parameters. In order to distinguish, the constraints here are called second constraints. The second constraint specifically requires a positive correlation between the current remaining capacity of any battery stack and its reference difference. The reference difference is the difference between the first ratio and the second ratio. The first ratio is the ratio of the battery stack's DC active power to its DC voltage, while the second ratio is the ratio of the DC active power to its DC voltage of the other DC energy source. The parameter considered here primarily reflects the second actual AC power of the other DC power supply system.

[0200] Here, the ratio of the DC active power to the DC voltage of the battery stack can still be expressed by the DC bus current (I DC,i The ratio of DC active power to DC voltage of other DC energy can be expressed as the DC current of each other energy supply system (I DG ) is represented. In the disclosed embodiment, the current remaining capacity of each battery stack is obtained. By comparing the current remaining margins, the relative ratio between the DC bus current and the DC current of other energy supply systems can be obtained. For the purpose of distinction, the relative ratio between the relative differences is referred to as the third relative ratio.

[0201] Based on the positive correlation between the current remaining capacity of the battery stack and the reference difference value of the battery stack, the third relative ratio between the relative differences is obtained based on the first relative ratio between the current remaining capacity of the battery stack. Specifically, it can be expressed as follows:

[0202] It can also be specifically reflected as:

[0203] After determining the third relative ratio between the relative differences, combined with the DC voltage obtained in the embodiment of the present disclosure, the DC voltage of each battery stack is combined with the third relative ratio of the battery stack to calculate the ratio between the DC active powers of each battery stack. Combined with the power balance principle (the power balance principle is that the total power input of the battery energy storage system and other energy supply systems is equal to the total power output; the total power input is the first actual AC power of all battery stacks and the second actual AC power of other energy supply systems, and the total power input is the sum of the DC active power of each battery stack and the second actual AC power of other energy supply systems), the first actual AC power is distributed to each battery stack according to the third relative ratio to obtain the DC active power of each battery stack. After obtaining the DC active power of each battery stack, the DC active power is converted to obtain the AC active power of the battery stack.

[0204] In an optional embodiment, due to factors such as loss of electrical energy during use, in order to improve accuracy, the disclosed embodiment also needs to consider the actual working efficiency of the PCS. That is, when calculating the DC active power based on the power balance principle, the total power input here is the first actual AC power of all battery stacks; the total power output here is the DC active power (P) of each battery stack at the actual working efficiency. AC,i Multiply by η i When converting DC active power, it is also necessary to consider the actual working efficiency of the PCS and make the conversion based on the working efficiency.

[0205] To improve the efficiency of calculating DC active power, the disclosed embodiment employs a matrix operation formula. Specifically, the third relative ratio, the first actual AC power, the DC active power of each other DC energy system, and the DC voltage of each bidirectional energy storage converter are used as known quantities, and the DC active power of each battery stack is used as the variable to be determined. Based on the principle of power balance, a second matrix operation formula is constructed; the second matrix operation formula is solved to obtain the DC active power of each battery stack.

[0206] The constructed second matrix operation formula is specifically: the product of the third known matrix and the second matrix to be determined is equal to the fourth known matrix. The third known matrix is ​​constructed based on the third relative ratio between the reference differences of the battery stacks, the DC voltage of each bidirectional energy storage converter, and the operating efficiency. The fourth known matrix is ​​constructed based on the first actual AC power, the second actual AC power, and the DC active power of each other DC energy system. The second matrix to be determined is constructed based on the DC active power of each battery stack and the DC active power of each other DC energy system.

[0207] In specific implementation, the power balancing principle in this embodiment can be expressed as:

[0208] The second matrix operation formula constructed based on the power balance principle is: A*x=b; specifically:

[0209] Among them, the variable to be determined is: x = A -1 *b. By solving for x, the AC active power of each battery stack can be obtained.

[0210] The conversion of the AC active power of each battery stack can be performed in the following manner:

[0211] The battery energy storage system in this disclosure may also have AC coupling with other energy supply systems in the same manner as the DC coupling with other energy supply systems, which will not be repeated here.

[0212] The present invention discloses that the remaining available capacity Cap of all battery stacks is used in the PCS grid-connected PQ control mode. i The DC bus current ratio corresponding to each stack is calculated, and the total power of the energy storage system is calculated based on the minimum power of each stack reported by the BMS to the EMS. The active power setpoint of each PCS is adjusted without affecting the charging and discharging power of the energy storage system. Taking into account the different working efficiency of each PCS and the inconsistent DC bus voltage caused by the inconsistency of the battery itself, the DC bus current is reasonably and accurately distributed and controlled to achieve full charge or full discharge status simultaneously between stacks, ensuring the charge and discharge depth of the entire system. At the same time, large differences in DC bus current between different PCSs are allowed. Because the stacks have independent thermal management systems, large differences in operating current will not lead to large consistency differences between battery clusters.

[0213] At the same time, by reasonably allocating current ratios to different battery clusters in each stack, the different available capacity SOCs of different battery clusters in the same battery stack can quickly converge to the same consistency with maximum capacity within the allowable operating current range under the DC / DC and the allocated current ratio, thereby reducing the capacity and SOC differences between different battery clusters in the same battery stack.

[0214] On the one hand, the present disclosure controls the active power setting of each PCS to control the current of each DC bus, so that each battery stack can be fully charged or fully discharged at the same time. On the other hand, it cooperates with the DC / DC current distribution algorithm to distribute the current ratio of battery clusters in the same stack, reducing system differences and greatly improving the consistency, lifespan, working efficiency and charge and discharge depth of the entire energy storage system.

[0215] FIG6 shows a schematic structural diagram of a control device provided by an embodiment of the present disclosure, which acts on a battery energy storage system. The battery energy storage system includes multiple battery stacks and an energy storage manager. Each battery stack includes a bidirectional energy storage converter, multiple DC power converters, and multiple battery clusters. Each battery cluster is sequentially connected to an AC power grid through the DC power converter and the bidirectional energy storage converter corresponding to the battery cluster. The energy storage manager is signal-connected to each DC power converter and the bidirectional energy storage converter respectively. The device includes:

[0216] a determination module, configured to determine, for each of the battery stacks, a current distribution target ratio to be set for each battery cluster according to battery cluster parameters of each battery cluster in the battery stack;

[0217] An acquisition module is used to obtain in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bidirectional energy storage converter;

[0218] a calculation module, configured to calculate the AC active power of each battery stack according to the first actual AC power, the current remaining capacity, and the DC voltage, in accordance with a preset first constraint condition;

[0219] A control module is used to send the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated to each bidirectional energy storage converter, and to control each DC power converter based on the current distribution target ratio to adjust the current allocated to each battery cluster.

[0220] According to a preset first constraint condition, the AC active power of each battery stack is calculated based on the acquired first actual AC power, the current remaining capacity, and the DC voltage; including:

[0221] Based on the power balance principle, the DC active power of the battery stack is calculated according to the first actual AC power, the current remaining capacity, the DC voltage and the first constraint condition;

[0222] The AC active power of each battery stack is calculated based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter.

[0223] The first constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference ratio of the battery stack; the reference ratio is the ratio of the DC active power to the DC voltage of the battery stack.

[0224] The method of calculating the DC active power of the battery stack based on the power balance principle and according to the first actual AC power, the current remaining capacity, the DC voltage, and the first constraint condition includes:

[0225] Based on a positive correlation between a current remaining capacity of any battery stack and a reference ratio of the battery stack, determining a second relative ratio between the reference ratios of the battery stacks according to the first relative ratios of the current remaining capacities between the battery stacks;

[0226] Based on the power balance principle, the DC active power of each battery stack is calculated according to the second relative ratio between the reference ratios of the battery stacks, the first actual AC power and the DC voltage of each bidirectional energy storage converter.

[0227] The method of calculating the DC active power of each battery stack based on the power balancing principle according to the second relative ratio between the reference ratios of the battery stacks, the first actual AC power, and the DC voltage of each bidirectional energy storage converter includes:

[0228] Based on the power balance principle, a first matrix operation formula is constructed; wherein the second relative ratio between the reference ratios of the battery stacks, the first actual AC power, and the DC voltage of each bidirectional energy storage converter are used as known quantities, and the DC active power of each battery stack is used as a variable to be determined;

[0229] The first matrix operation formula is solved to obtain the DC active power of each battery stack.

[0230] The first matrix operation formula includes a first known matrix, a second known matrix, and a first matrix to be determined; and the first matrix operation formula is constructed based on the power balance principle, including:

[0231] constructing the first known matrix according to a second relative ratio between the reference ratios of the battery stacks, a DC voltage and an operating efficiency of each bidirectional energy storage converter;

[0232] constructing the second known matrix according to the first actual AC power;

[0233] constructing the first matrix to be determined according to the DC active power of each of the battery stacks;

[0234] The product of the first known matrix and the first matrix to be determined is equal to the second known matrix.

[0235] The step of calculating the AC active power of each battery stack based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter includes:

[0236] Determining a conversion ratio corresponding to the DC active power of each bidirectional energy storage converter based on the working efficiency of the bidirectional energy storage converter;

[0237] According to the conversion ratio, the DC active power of the bidirectional energy storage converter is converted into the AC active power of the battery stack.

[0238] The power balancing principle is that the total power input of the battery energy storage system is equal to the total power output; the total power input is the first actual AC power of all battery stacks; the total power output is the sum of the DC active power of each battery stack.

[0239] Get the first actual AC power of all battery stacks by:

[0240] The energy storage manager obtains the sub-AC power of each battery stack;

[0241] Aggregate all the sub-AC powers to obtain the first total power of all battery stacks;

[0242] The first actual AC power is obtained by performing actual loss removal processing on the first total active power.

[0243] The bidirectional energy storage converter is also connected to other energy supply systems;

[0244] The AC active power of each battery stack is calculated by the following method, including:

[0245] The energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity and the DC voltage in accordance with the preset second constraint condition.

[0246] The energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity, and the DC voltage in accordance with a preset second constraint condition, including:

[0247] Based on the power balance principle, the DC active power of the battery stack is calculated according to the first actual AC power, the second actual AC power, the current remaining capacity, the DC voltage, the DC active power of each other DC energy system, and the second constraint condition;

[0248] The AC active power of each battery stack is calculated based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter.

[0249] The second constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference difference of the battery stack; the reference difference is the difference between the first ratio and the second ratio; the first ratio is the ratio of the DC active power to the DC voltage of the battery stack, and the second ratio is the ratio of the DC active power to the DC voltage of other DC energy sources.

[0250] The method of calculating the DC active power of the battery stack based on the power balancing principle and according to the first actual AC power, the second actual AC power, the current remaining capacity, the DC voltage, the DC active power of each other DC energy system, and the second constraint condition includes:

[0251] Based on a positive correlation between the current remaining capacity of the battery stack and the reference difference value of the battery stack, calculating a third relative ratio between the reference difference values ​​of the battery stacks according to the first relative ratio between the current remaining capacity of the battery stacks;

[0252] Based on the power balance principle, the DC active power of each battery stack is calculated according to the third relative ratio, the first actual AC power, the second actual AC power, the DC active power of each other DC energy system and the DC voltage of each bidirectional energy storage converter.

[0253] The method of calculating the DC active power of each battery stack based on the power balance principle according to the third relative ratio, the first actual AC power, the second actual AC power, the DC active power of each other DC energy system, and the DC voltage of each bidirectional energy storage converter includes:

[0254] Based on the power balance principle, a second matrix operation formula is constructed; wherein the third relative ratio, the first actual AC power, the DC active power of each other DC energy system, and the DC voltage of each bidirectional energy storage converter are used as known quantities, and the DC active power of each battery stack is used as a variable to be determined;

[0255] The second matrix operation formula is solved to obtain the DC active power of each battery stack.

[0256] The second matrix operation formula includes a third known matrix, a fourth known matrix, and a second matrix to be determined; and the second matrix operation formula is constructed based on the power balance principle, including:

[0257] constructing the third known matrix according to a third relative ratio between the reference difference values ​​of the battery stacks, the DC voltage and the operating efficiency of each bidirectional energy storage converter;

[0258] constructing the fourth known matrix according to the first actual AC power, the second actual AC power and the DC active power of each other DC energy system;

[0259] constructing the second matrix to be determined according to the DC active power of each of the battery stacks and the DC active power of each other DC energy system;

[0260] The product of the third known matrix and the second matrix to be determined is equal to a fourth known matrix.

[0261] The step of calculating the AC active power of each battery stack based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter includes:

[0262] Determining a conversion ratio corresponding to the DC active power of each bidirectional energy storage converter based on the working efficiency of the bidirectional energy storage converter;

[0263] According to the conversion ratio, the DC active power of the bidirectional energy storage converter is converted into the AC active power of the battery stack.

[0264] The power balancing principle is that the total power input of the battery energy storage system and other energy power supply systems is equal to the total power output; the total power input is the first actual AC power of all battery stacks and the second actual AC power of other energy power supply systems, and the total power input is the sum of the DC active power of each battery stack and the second actual AC power of other energy power supply systems.

[0265] The current distribution target ratio is within the distribution ratio constraint interval, and the battery cluster parameters include at least one of the following items: a current remaining capacity of the battery cluster, a capacity setting critical value, and an distribution ratio constraint interval set for each battery cluster based on the total number of battery clusters connected in parallel in the battery energy storage system.

[0266] The step of determining the allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters connected in parallel in the battery energy storage system includes:

[0267] When system parameters of the battery energy storage system do not satisfy the current sharing condition, an allocation ratio constraint interval set for each battery cluster is determined according to the total number of battery clusters connected in parallel in the battery energy storage system.

[0268] The step of determining the allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters connected in parallel in the battery energy storage system includes:

[0269] Obtaining a total number of battery clusters in a plurality of battery clusters connected in parallel in the battery energy storage system and an overload constraint ratio of the battery energy storage system, wherein the overload constraint ratio represents a preset ratio at which a current of the battery cluster exceeds a rated current range during charging or discharging;

[0270] According to the overload constraint ratio, an upper limit and a lower limit of an allocation ratio constraint of the battery energy storage system are determined to determine an allocation ratio constraint interval set for each battery cluster.

[0271] The battery cluster parameters include the current remaining capacity of the battery cluster and a capacity setting critical value; wherein the capacity setting critical value represents the fastest convergence of each battery cluster in the battery energy storage system to a consistent state of charge;

[0272] The determining of the current distribution target ratio set for each battery cluster according to the battery cluster parameters includes:

[0273] determining a first current distribution ratio to be adjusted for each battery cluster according to the current remaining capacity of each battery cluster and the capacity setting critical value;

[0274] The current distribution target ratio is determined according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval.

[0275] Each battery cluster corresponds to one of the DC power converters, and each battery stack corresponds to one of the bidirectional energy storage converters; wherein the battery cluster and the DC power converter corresponding to the battery cluster are packaged together.

[0276] As shown in Figure 7, an embodiment of the present disclosure provides an electronic device for executing the control method of the present disclosure. The device includes a memory, a processor, a bus, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the control method when executing the computer program.

[0277] Specifically, the above-mentioned memory and processor may be general-purpose memory and processor, which are not specifically limited here. When the processor runs the computer program stored in the memory, the above-mentioned control method can be executed.

[0278] Corresponding to the control method in the present disclosure, an embodiment of the present disclosure further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned control method are executed.

[0279] Specifically, the storage medium can be a general storage medium, such as a mobile disk, a hard disk, etc. When the computer program on the storage medium is run, the above-mentioned control method can be executed.

[0280] In the embodiments provided in the present disclosure, it should be understood that the disclosed systems and methods can be implemented in other ways. The system embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. There may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed may be through some communication interface, indirect coupling or communication connection of the system or unit, which may be electrical, mechanical or other forms.

[0281] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0282] In addition, each functional unit in the embodiments provided in the present disclosure 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.

[0283] 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 computer-readable storage medium. Based on this understanding, the technical solution of the present disclosure, 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 enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present disclosure. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0284] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0285] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present disclosure, which are used to illustrate the technical solutions of the present disclosure, rather than to limit them. The scope of protection of the present disclosure is not limited thereto. Although the present disclosure has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed in the present disclosure, or replace some of the technical features therein with equivalents. However, these modifications, changes, or replacements do not deviate from the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present disclosure. They should all be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be based on the scope of protection of the claims. Industrial Applicability

[0286] The method disclosed herein includes, for each of the battery stacks, the energy storage manager determining a current distribution target ratio set for each battery cluster based on the battery cluster parameters of each battery cluster in the battery stack; the energy storage manager obtaining in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks and the DC voltage of each bidirectional energy storage converter; the energy storage manager calculating the AC active power of each of the battery stacks according to a preset first constraint condition based on the first actual AC power, the current remaining capacity and the DC voltage; the energy storage manager sending the AC active power to the corresponding bidirectional energy storage converter to adjust the current distributed to each of the bidirectional energy storage converters, and controlling each of the DC power converters based on the current distribution target ratio to adjust the current distributed to each battery cluster.

[0287] The present disclosure controls the AC active power given to the bidirectional energy storage converter, thereby controlling the current of each DC bus, so that each battery stack can be fully charged or fully discharged at the same time. On the other hand, it also distributes the current ratio of battery clusters in the same stack to reduce system differences, greatly improving the consistency, lifespan, working efficiency and charge and discharge depth of the entire battery energy storage system.

[0288] Furthermore, it is understood that the control method, apparatus, electronic device, and storage medium provided by the embodiments of the present disclosure are reproducible and can be used in a variety of industrial applications. For example, the control method, apparatus, electronic device, and storage medium provided by the embodiments of the present disclosure can be used in the field of circuit control technology.

Claims

1. A control method, characterized in that, Act on a battery energy storage system, which includes a plurality of battery stacks and an energy storage manager; each of the battery stacks includes a bidirectional energy storage converter, a plurality of DC power converters, and a plurality of battery clusters; each battery cluster is sequentially connected to the AC grid through the DC power converter and the bidirectional energy storage converter corresponding to the battery cluster; the energy storage manager is respectively connected to each DC power converter and the bidirectional energy storage converter by signals; the method includes: For each of the battery stacks, the energy storage manager determines the current distribution target ratio set for each battery cluster according to the battery cluster parameters of each battery cluster in the battery stack; The energy storage manager obtains in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bidirectional energy storage converter; The energy storage manager calculates the AC active power of each of the battery stacks according to the obtained first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint condition; The energy storage manager sends the AC active power to the corresponding bidirectional energy storage converter to adjust the current distributed by each bidirectional energy storage converter, and controls each DC power converter based on the current distribution target ratio to adjust the current distributed by each battery cluster.

2. The method according to claim 1, wherein The energy storage manager calculates the AC active power of each of the battery stacks according to the obtained first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint condition; Including: Based on the power balance principle, calculate the DC active power of the battery stack according to the first actual AC power, the current remaining capacity, the DC voltage, and the first constraint condition; Calculate the AC active power of each of the battery stacks according to the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter.

3. The method according to claim 2, wherein The first constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference ratio of the battery stack; the reference ratio is the ratio of the DC active power of the battery stack to the DC voltage.

4. The method according to claim 3, characterized in that The calculating the DC active power of the battery stack based on the power balance principle according to the first actual AC power, the current remaining capacity, the DC voltage, and the first constraint condition includes: Based on the positive correlation between the current remaining capacity of any battery stack and the reference ratio of the battery stack, determine the second relative ratio between the reference ratios of each battery stack according to the first relative ratio of the current remaining capacity between each battery stack; Based on the power balance principle, calculate the DC active power of each of the battery stacks according to the second relative ratio between the reference ratios of each battery stack, the first actual AC power, and the DC voltage of each bidirectional energy storage converter.

5. The method according to claim 4, wherein The calculating the DC active power of each of the battery stacks based on the power balance principle according to the second relative ratio between the reference ratios of each battery stack, the first actual AC power, and the DC voltage of each bidirectional energy storage converter includes: Based on the power balance principle, a first matrix operation formula is constructed; wherein the second relative ratio between the reference ratios of each battery stack, the first actual AC power and the DC voltage of each bidirectional energy storage converter are used as known quantities, and the DC active power of each battery stack is used as a variable to be determined. The first matrix operation formula is solved to obtain the DC active power of each battery stack.

6. The method according to claim 5, wherein The first matrix operation formula includes a first known matrix, a second known matrix and a first matrix to be determined; the first matrix operation formula is constructed based on the power balance principle, including: constructing the first known matrix according to the second relative ratio between the reference ratios of the battery stacks, the DC voltage and the working efficiency of each bidirectional energy storage converter; constructing the second known matrix according to the first actual AC power; Constructing the first matrix to be determined according to the DC active power of each of the battery stacks; The product of the first known matrix and the first matrix to be determined is equal to the second known matrix.

7. The method according to claim 2, characterized in that The method of calculating the AC active power of each battery stack according to the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter includes: According to the working efficiency of each bidirectional energy storage converter, a conversion ratio corresponding to the DC active power of the bidirectional energy storage converter is determined; According to the conversion ratio, the DC active power of the bidirectional energy storage converter is converted into the AC active power of the battery stack.

8. The method according to claim 2, wherein The power balancing principle is that the total power input of the battery energy storage system is equal to the total power output; the total power input is the first actual AC power of all battery stacks; and the total power output is the sum of the DC active power of each battery stack.

9. The method according to claim 1, characterized in that The energy storage manager obtains the first actual AC power of all battery stacks in the following manner: The energy storage manager obtains the sub-AC power of each battery stack; Aggregate all the sub-AC powers together to obtain the first total power of all battery stacks; The first actual AC power is obtained by performing actual loss removal processing on the first total power.

10. The method according to claim 1, characterized in that, The bidirectional energy storage converter is also connected to other energy supply systems; The energy storage manager calculates the AC active power of each battery stack in the following manner, including: The energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity and the DC voltage in accordance with the preset second constraint condition.

11. The method according to claim 10, characterized in that, The energy storage manager calculates the AC active power of each battery stack according to the first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity and the DC voltage according to the preset second constraint condition, including: Based on the power balance principle, the DC active power of the battery stack is calculated according to the first actual AC power, the second actual AC power, the current remaining capacity, the DC voltage, the DC active power of each other DC energy system and the second constraint condition; The AC active power of each battery stack is calculated based on the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter.

12. The method according to claim 11, wherein The second constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference difference of the battery stack; the reference difference is the difference between the first ratio and the second ratio; the first ratio is the ratio of the DC active power of the battery stack to the DC voltage, and the second ratio is the ratio of the DC active power of other DC energy sources to the DC voltage.

13. The method according to claim 12, characterized in that, Based on the power balance principle, according to the first actual AC power, the second actual AC power, the current remaining capacity, the DC voltage, the DC active power of each other DC energy source system, and the second constraint condition, calculating the DC active power of the battery stack includes: Based on the fact that the current remaining capacity of the battery stack is positively correlated with the reference difference of the battery stack, according to the first relative ratio between the current remaining capacities of each battery stack, calculating the third relative ratio between the reference differences of each battery stack; Based on the power balance principle, according to the third relative ratio, the first actual AC power, the second actual AC power, the DC active power of each other DC energy source system, and the DC voltage of each bidirectional energy storage converter, calculating the DC active power of each battery stack.

14. The method according to claim 13, wherein Based on the power balance principle, according to the third relative ratio, the first actual AC power, the second actual AC power, the DC active power of each other DC energy source system, and the DC voltage of each bidirectional energy storage converter, calculating the DC active power of each battery stack includes: Based on the power balance principle, constructing a second matrix operation formula; wherein, the third relative ratio, the first actual AC power, the DC active power of each other DC energy source system, and the DC voltage of each bidirectional energy storage converter are used as known quantities, and the DC active power of each battery stack is used as a variable to be solved, Solving the second matrix operation formula to obtain the DC active power of each battery stack.

15. The method according to claim 14, wherein The second matrix operation formula includes a third known matrix, a fourth known matrix, and a second matrix to be solved; based on the power balance principle, constructing the second matrix operation formula includes: Constructing the third known matrix according to the third relative ratio between the reference differences of each battery stack, the DC voltage, and the working efficiency of each bidirectional energy storage converter; Constructing the fourth known matrix according to the first actual AC power, the second actual AC power, and the DC active power of each other DC energy source system; Constructing the second matrix to be solved according to the DC active power of each battery stack and the DC active power of each other DC energy source system; The product of the third known matrix and the second matrix to be solved is equal to the fourth known matrix.

16. The method according to claim 11, wherein Calculating the AC active power of each battery stack according to the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter includes: Determining the conversion ratio corresponding to the DC active power of the bidirectional energy storage converter according to the working efficiency of each bidirectional energy storage converter; Converting the DC active power of the bidirectional energy storage converter into the AC active power of the battery stack according to the conversion ratio.

17. The method according to claim 11, wherein The power balance principle is that the total power input of the battery energy storage system and other energy supply systems is equal to the total power output; the total power input is the first actual AC power of all battery stacks and the second actual AC power of other energy supply systems, and the total power input is the sum of the DC active power of each battery stack and the second actual AC power of other energy supply systems.

18. The method according to claim 1, wherein The current distribution target ratio is within the distribution ratio constraint interval, and the battery cluster parameters include at least one of the following items: the current remaining capacity of the battery cluster, the capacity setting critical value, and the distribution ratio constraint interval set for each battery cluster determined according to the total number of battery clusters in the battery energy storage system connected in parallel.

19. The method according to claim 18, wherein Determining the distribution ratio constraint interval set for each battery cluster according to the total number of battery clusters in the battery energy storage system connected in parallel includes: When the system parameters of the battery energy storage system do not meet the current equalization condition, determining the distribution ratio constraint interval set for each battery cluster according to the total number of battery clusters in the battery energy storage system connected in parallel.

20. The method according to claim 18, wherein Determining the distribution ratio constraint interval set for each battery cluster according to the total number of battery clusters in the battery energy storage system connected in parallel includes: Obtaining the total number of battery clusters in the battery energy storage system connected in parallel and the overload constraint ratio of the battery energy storage system, where the overload constraint ratio represents a preset ratio of the current of the battery cluster exceeding the rated current range during charging or discharging; According to the overload constraint ratio, determining the upper limit and lower limit of the distribution ratio constraint of the battery energy storage system to determine the distribution ratio constraint interval set for each battery cluster.

21. The method according to claim 1, characterized in that, The battery cluster parameters include the current remaining capacity of the battery cluster and the capacity setting critical value; wherein, the capacity setting critical value represents the fastest convergence of each battery cluster in the battery energy storage system to a consistent state of charge. Determining the current distribution target ratio set for each battery cluster according to the battery cluster parameters includes: Determining the first current distribution ratio to be adjusted set for each battery cluster according to the current remaining capacity of each battery cluster and the capacity setting critical value; Determining the current distribution target ratio according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval.

22. The method according to claim 1, characterized in that, Each battery cluster corresponds to one of the DC power converters, and each battery stack corresponds to one of the bidirectional energy storage inverters; wherein, the battery cluster and the DC power converter corresponding to the battery cluster are packaged together.

23. A control device, characterized in that, Acting on the battery energy storage system, the battery energy storage system includes a plurality of battery stacks and an energy storage manager; each battery stack includes a bidirectional energy storage inverter, a plurality of DC power converters, and a plurality of battery clusters; each battery cluster is sequentially connected to the AC grid through the DC power converter and the bidirectional energy storage inverter corresponding to the battery cluster; the energy storage manager is respectively connected to each DC power converter and bidirectional energy storage inverter in signal connection; the device includes: A determination module, configured to, for each battery stack, determine the current distribution target ratio set for each battery cluster according to the battery cluster parameters of each battery cluster in the battery stack. An acquisition module, configured to acquire in real time the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bidirectional energy storage converter; A calculation module, configured to calculate the AC active power of each battery stack according to a preset first constraint condition based on the acquired first actual AC power, the current remaining capacity, and the DC voltage; A control module, configured to send the AC active power to the corresponding bidirectional energy storage converter to adjust the current distributed by each bidirectional energy storage converter, and control each DC power converter based on the current distribution target ratio to adjust the current distributed by each battery cluster.

24. An electronic device, characterized in that, Comprising: A processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device runs, the processor communicates with the memory through the bus. When the machine-readable instructions are executed by the processor, the steps of the control method according to any one of claims 1 to 22 are executed.

25. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium. When the computer program is run by the processor, the steps of the control method according to any one of claims 1 to 22 are executed.

Images