Control method and device, electronic equipment and storage medium

Abstract

The invention provides a control method and device, electronic equipment and a storage medium, and the method comprises the steps: issuing AC active power to a corresponding bidirectional energy storage converter so as to adjust the current distributed by each bidirectional energy storage converter, and controlling each DC power converter based on a current distribution target ratio, therefore, the current distributed to each battery cluster is adjusted. According to the invention, by controlling the given AC active power issued to the bidirectional energy storage converter, the current of each DC bus is controlled, each cell stack is fully charged or fully discharged at the same time, on the other hand, the current proportion of the cell clusters in the same stack is distributed, the system difference is reduced, and the system reliability is improved. And the consistency, the service life, the working efficiency and the charge-discharge depth of the whole battery energy storage system are greatly improved.

Description

Technical Field

[0001] The present application relates to the technical field of circuit control, and in particular, to a control method, device, electronic device, and storage medium. Background Art

[0002] The power of a single battery cluster can no longer meet people's needs. In order to meet the growing power requirements of people, a battery energy storage system has emerged. The battery energy storage system is composed of multiple battery stacks connected in parallel, and each battery stack is composed of multiple battery clusters connected in parallel. In order to extend the service life of the battery energy storage system, during use (charging and discharging), it is necessary to try to ensure that the remaining power of each battery cluster in the battery energy storage system is in the same state.

[0003] In the prior art, the current distribution of battery clusters is based on the capacity ratio of the battery clusters. The accuracy of this distribution method is poor, and during use, some battery stacks will still reach the full charge state or full discharge state first, resulting in inconsistent disconnection times of this battery stack and other battery stacks from the operating state, affecting the utilization rate of the entire energy storage system and the depth of discharge (DoD). Summary of the Invention

[0004] In view of this, the purpose of the present application is to provide a control method, device, electronic device, and storage medium to overcome the problems in the prior art.

[0005] In a first aspect, an embodiment of the present application provides a control method, 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 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:

[0006] For each battery stack, 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;

[0007] The energy storage manager real-time 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;

[0008] The energy storage manager calculates the AC active power of each battery stack according to the obtained first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint condition;

[0009] The energy storage manager issues 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.

[0010] In some technical solutions of this application, the above energy storage manager calculates the AC active power of each battery stack according to the obtained first actual AC power, the current remaining capacity, and the DC voltage in accordance with a preset first constraint condition, including:

[0011] 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.

[0012] The AC active power of each battery stack is calculated according to the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter.

[0013] In some technical solutions of this application, the above 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.

[0014] In some technical solutions of this application, the above-mentioned calculation of 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:

[0015] Based on the positive correlation between the current remaining capacity of any battery stack and the reference ratio of the battery stack, the second relative ratio between the reference ratios of each battery stack is determined according to the first relative ratio of the current remaining capacity between each battery stack.

[0016] 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 each battery stack, the first actual AC power, and the DC voltage of each bidirectional energy storage converter.

[0017] In some technical solutions of this application, the above-mentioned calculation of the DC active power of each battery stack 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:

[0018] 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;

[0019] The first matrix operation formula is solved to obtain the DC active power of each battery stack.

[0020] In some technical solutions of the present application, 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:

[0021] 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;

[0022] constructing the second known matrix according to the first actual AC power;

[0023] Constructing the first matrix to be determined according to the DC active power of each of the battery stacks;

[0024] The product of the first known matrix and the first matrix to be determined is equal to the second known matrix.

[0025] In some technical solutions of the present application, 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:

[0026] 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;

[0027] 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.

[0028] In some technical solutions of the present application, the above-mentioned 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.

[0029] In some technical solutions of the present application, the energy storage manager obtains the first actual AC power of all battery stacks in the following manner:

[0030] The energy storage manager obtains the sub-AC power of each battery stack;

[0031] Aggregate all the sub-AC powers together to obtain the first total power of all battery stacks;

[0032] By performing actual loss reduction processing on the first total power, the first actual AC power is obtained.

[0033] In some technical solutions of the present application, the above-mentioned bidirectional energy storage converter is also connected to other energy supply systems;

[0034] The energy storage manager calculates the AC active power of each battery stack in the following manner, including:

[0035] The energy storage manager calculates the AC active power of each battery stack according to the preset second constraint condition, based on the obtained first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity, and the DC voltage.

[0036] In some technical solutions of the present application, the above-mentioned energy storage manager calculates the AC active power of each battery stack according to the preset second constraint condition, based on the obtained first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity, and the DC voltage, including:

[0037] 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 condition, the DC active power of the battery stack is calculated;

[0038] According to the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter, the AC active power of each battery stack is calculated.

[0039] In some technical solutions of the present application, the above-mentioned second constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference difference value of this battery stack; the reference difference value 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 to the DC voltage.

[0040] In some technical solutions of the present application, the above-mentioned 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 condition, the DC active power of the battery stack is calculated, including:

[0041] Based on the fact that the current remaining capacity of the battery stack is positively correlated with the reference difference value of this battery stack, according to the first relative comparison between the current remaining capacities of each battery stack, the third relative comparison between the reference difference values of each battery stack is calculated;

[0042] Based on the power balance principle, calculate the DC active power of each of the battery stacks according to the third-phase comparison, 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.

[0043] In some technical solutions of the present application, the above-mentioned calculating the DC active power of each of the battery stacks based on the power balance principle according to the third-phase comparison, 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:

[0044] Based on the power balance principle, construct a second matrix operation formula; wherein, the third-phase comparison, 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 of the battery stacks is used as a variable to be solved.

[0045] Solve the second matrix operation formula to obtain the DC active power of each of the battery stacks.

[0046] In some technical solutions of the present application, the above-mentioned second matrix operation formula includes a third known matrix, a fourth known matrix, and a second matrix to be solved; the constructing the second matrix operation formula based on the power balance principle includes:

[0047] Construct the third known matrix according to the third-phase comparison between the reference differences of each battery stack, the DC voltage and the working efficiency of each bidirectional energy storage converter;

[0048] Construct 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;

[0049] Construct the second matrix to be solved according to the DC active power of each of the battery stacks and the DC active power of each other DC energy system;

[0050] The product of the third known matrix and the second matrix to be solved is equal to the fourth known matrix.

[0051] In some technical solutions of the present application, the above-mentioned calculating 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 includes:

[0052] Determine 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;

[0053] Convert the DC active power of the bidirectional energy storage converter into the AC active power of the battery stack according to the conversion ratio.

[0054] In some technical solutions of the present application, the above 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.

[0055] In some technical solutions of the present application, the above 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 according to the total number of battery clusters connected in parallel in the battery energy storage system.

[0056] In some technical solutions of the present application, the above-mentioned distribution 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:

[0057] When the system parameters of the battery energy storage system do not meet the current equalization condition, determine the distribution 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.

[0058] In some technical solutions of the present application, the above-mentioned distribution 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:

[0059] Obtain the total number of battery clusters connected in parallel in the battery energy storage system and the overload constraint ratio of the battery energy storage system, where the overload constraint ratio represents the preset ratio of the current of the battery cluster exceeding the rated current range during charging or discharging;

[0060] According to the overload constraint ratio, determine 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.

[0061] In some technical solutions of the present application, the above 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.

[0062] The above-mentioned determination of the current distribution target ratio set for each battery cluster according to the battery cluster parameters includes:

[0063] Determine the first current allocation ratio to be adjusted for each battery cluster according to the current remaining capacity of each battery cluster and the set critical value of the capacity.

[0064] Determine the target current allocation ratio according to whether the first current allocation ratio to be adjusted is within the allocation ratio constraint interval.

[0065] In some technical solutions of the present application, each of the above battery clusters 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.

[0066] In a second aspect, an embodiment of the present application provides a control device for a battery energy storage system, the battery energy storage system including 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 in a signal connection; the device includes:

[0067] A determination module, configured to, for each of the battery stacks, determine the target current allocation ratio to be set for each battery cluster according to the battery cluster parameters of each battery cluster in the battery stack;

[0068] 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;

[0069] A calculation module, configured to calculate the AC active power of each of the battery stacks according to the acquired first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint condition;

[0070] A control module, configured to send the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated by each bidirectional energy storage converter, and control each DC power converter based on the target current allocation ratio to adjust the current allocated by each battery cluster.

[0071] In a third aspect, an embodiment of the present application provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and the steps of the above control method are implemented when the processor executes the computer program.

[0072] Fourthly, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is run by a processor, the steps of the above control method are executed.

[0073] The technical solutions provided by the embodiments of the present application may include the following beneficial effects:

[0074] The method of the present application includes, for each of the battery stacks, the energy storage manager determining a 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 acquiring 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 battery stack according to the acquired first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint condition; the energy storage manager sending the AC active power to the corresponding bidirectional energy storage converter to adjust the current distributed by each bidirectional energy storage converter, and controlling each DC power converter based on the current distribution target ratio to adjust the current distributed by each battery cluster.

[0075] By controlling the given AC active power sent to the bidirectional energy storage converter, the present application controls the DC bus current of each path, so that each battery stack reaches full charge or full discharge simultaneously. On the other hand, by cooperating with the distribution of the current ratio of the battery clusters in the same stack, the system difference is reduced, and the consistency, lifespan, working efficiency, and charge and discharge depth of the entire battery energy storage system are greatly improved.

[0076] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specific preferred embodiments are given below in conjunction with the accompanying drawings for detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0078] Figure 1 It shows a schematic flowchart of a control method provided by an embodiment of the present application;

[0079] Figure 2 It shows a schematic diagram of a battery energy storage system provided by an embodiment of the present application;

[0080] Figure 3Shows another schematic diagram of the battery energy storage system provided by the embodiments of the present application;

[0081] Figure 4 Shows a schematic circuit connection diagram of the AC coupling between a battery energy storage system provided by the embodiments of the present application and other energy systems;

[0082] Figure 5 Shows a schematic circuit connection diagram of the DC coupling between a battery energy storage system provided by the embodiments of the present application and other energy systems;

[0083] Figure 6 Is a schematic diagram of a control device provided by the embodiments of the present application;

[0084] Figure 7 Is a schematic structural diagram of an electronic device provided by the embodiments of the present application. Detailed implementation manners

[0085] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It should be understood that the accompanying drawings in the present application are only for the purposes of illustration and description, and are not used to limit the protection scope of the present application. In addition, it should be understood that the schematic drawings are not drawn to actual scale. The flowcharts used in the present application illustrate the operations implemented according to some embodiments of the present application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and the steps without logical context relationships may be reversed or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart or remove one or more operations from the flowchart under the guidance of the content of the present application.

[0086] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application to be protected, but only represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present application.

[0087] It should be noted that the term "including" will be used in the embodiments of the present application to indicate the existence of the features stated hereinafter, but does not exclude adding other features.

[0088] The power of a single battery cluster can no longer meet people's needs. In order to meet the growing power requirements of people, a battery energy storage system has emerged. The battery energy storage system is composed of multiple battery stacks connected in parallel, and each battery stack is composed of multiple battery clusters connected in parallel. In order to extend the service life of the battery energy storage system, during use (charging and discharging), it is necessary to try to ensure that the remaining power of each battery cluster in the battery energy storage system is in the same state.

[0089] In the prior art, the current is distributed to the battery clusters according to the capacity ratio of the battery clusters. The accuracy of this distribution method is poor, and during use, there will still be some battery stacks reaching the full charge state or full discharge state earlier, resulting in inconsistent disconnection times of this battery stack and other battery stacks from the operating state, affecting the utilization rate of the entire energy storage system and the depth of discharge (DoD).

[0090] Based on this, the embodiments of the present application provide a control method, device, electronic device, and storage medium, which will be described below through embodiments.

[0091] Figure 1 The flowchart of a control method provided by the embodiments of the present application is shown. This method acts on a battery energy storage system, where this method includes S101 - S104; specifically:

[0092] S101. 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;

[0093] S102. The energy storage manager real - time obtains the current remaining capacity of each battery stack, the first actual AC power of all battery stacks, and the DC voltage of each bi - directional energy storage converter;

[0094] S103. 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;

[0095] S104. The energy storage manager sends the AC active power to the corresponding bi - directional energy storage converter to adjust the current distributed by each bi - directional energy storage converter, and controls each DC power converter based on the current distribution target ratio to adjust the current distributed to each battery cluster.

[0096] By controlling the AC active power reference sent to the bidirectional energy storage converter, the DC bus current of each path is controlled, enabling each battery stack to reach full charge or full discharge simultaneously. On the other hand, by coordinating the distribution of the current ratio among the battery clusters within the same stack, the system difference is reduced, significantly enhancing the consistency, lifespan, working efficiency, and charge-discharge depth of the entire battery energy storage system.

[0097] Some embodiments of the present application will be described in detail below. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0098] Before introducing the control method of the present application, the battery energy storage system in the embodiments of the present application will be introduced first. The battery energy storage system in the prior art is only a parallel arrangement of multiple battery clusters and does not have a DC / DC. In a traditional energy storage system, generally multiple battery clusters are directly connected in parallel to the DC side of the PCS. This method will cause inter-cluster circulating current due to the existence of the inter-cluster voltage difference caused by the inconsistency between battery clusters. Excessive inter-cluster circulating current will affect the battery lifespan. And due to the inconsistency of the internal resistance, the magnitude of the current of each battery cluster during the charge and discharge process is determined by the internal resistance, which will continuously amplify the reduction of the discharge depth caused by the cask effect. After adding DCDC, the current of each cluster can be accurately controlled, thereby enhancing the system consistency and improving the discharge depth. Different from the parallel DCDC, the series DCDC has lower requirements for withstand voltage, the charge and discharge current range remains unchanged, and the output voltage is only dozens of volts. Compared with the parallel DCDC with hundreds or thousands of volts, it has lower power, smaller volume, and lower cost.

[0099] The PCS control algorithm includes PQ control (P is the active power, Q is the reactive power, which is the power control mode of the PCS), VF control (V is the voltage amplitude, F is the voltage frequency, which is the constant voltage control mode of the PCS), and droop control. The distribution algorithm in the control method of the present application is applicable to the PCS grid-connected PQ control algorithm.

[0100] As Figure 2 shown, the battery energy storage system in the embodiments of the present application includes multiple battery stacks and an energy storage manager; each of the battery stacks includes a bidirectional energy storage converter, multiple DC power converters, and multiple battery clusters; each battery cluster is sequentially connected to the AC grid through the DC power converter corresponding to the battery cluster and the bidirectional energy storage converter; the energy storage manager is respectively connected to each DC power converter and the bidirectional energy storage converter in a signal connection. 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. In an optional embodiment, as Figure 3As shown in the figure, the energy storage manager in the embodiment of the present application includes a Battery Management System (BMS) and an Energy Management System (EMS). That is, in this embodiment, the management work of the energy storage manager in the above embodiment is jointly undertaken by the BMS and the EMS. It should be noted that in Figure 2 and Figure 3 , the solid connecting line represents an electrical connection, and the connecting line with intervals represents a signal connection. The dashed boxes outside Battery Cluster 1 to Battery Cluster 3 indicate that Battery Cluster 1 to Battery Cluster 3 (including the corresponding DC / DCs of Battery Cluster 1 to Battery Cluster 3) are encapsulated in a housing. The dashed box outside the DC / DC in the figure only serves to group all the DC / DCs into an overall unit and does not represent a physical position relationship. In Figure 3 In the system shown, the control method in the prior art cannot directly control the DC current magnitude of each energy storage PCS through EMS instructions, and the efficiency of each PCS and the DC bus voltage of each DC side are not the same due to the inconsistency of the battery clusters. The DC bus current of each DC bus is independent and has no coupling. Directly allocating the total power based on the capacity ratio of each battery stack makes it difficult to accurately control the DC bus current, so that when the energy storage system is connected to the grid, a certain energy storage battery stack or container reaches the full charge or full discharge state first, resulting in the withdrawal of this stack from the operating state, affecting the availability and DOD of the entire energy storage system.

[0101] For Figure 2 In the system shown, in the control method from S101 to S104, it can be controlled in two levels. The first level is the control of the energy storage manager on the DC / DC side. Specifically: for each of the battery stacks, the energy storage manager determines the current allocation target ratio set for each battery cluster according to the battery cluster parameters of each battery cluster in the battery stack; based on the current allocation target ratio, controls each of the DC power converters to adjust the current allocated to each battery cluster. The second level is the control of the energy storage manager on 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 of the battery stacks according to the obtained first actual AC power, the current remaining capacity, and the DC voltage in accordance with a preset first constraint condition; the energy storage manager issues the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated to each bidirectional energy storage converter.

[0102] For Figure 3For the system shown, in the control methods of S101 to S104, it can be divided into two levels for control. The first level is the control of the BMS on the DC / DC side. Specifically: for each of the battery stacks, the BMS determines the target current distribution ratio set for each battery cluster according to the battery cluster parameters of each battery cluster in the battery stack; based on the target current distribution ratio, controls each of the DC power converters to adjust the current allocated to each battery cluster. The second level is the control of the EMS on the PCS side. Specifically: the EMS 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 EMS 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 in accordance with a preset first constraint condition; the EMS sends the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated to each of the bidirectional energy storage converters.

[0103] In specific implementation, the EMS is respectively set to multiple levels in each battery stack (for example, it can be set in the manner of battery pack, battery cluster, and battery stack). Obtain the battery pack power data from each battery pack at the lower level, and then summarize to obtain the sub-AC power of each battery stack. Gather all the sub-AC powers together to obtain the first total power (P0) of all battery stacks; through actual loss reduction processing on the first total power, obtain the first actual AC power (P * ). P* is the AC side power actually operating in the entire energy storage system. The specific actual loss reduction processing is manually input according to requirements, or can be based on an optimization algorithm (considering benefits, battery health, temperature, etc.), but it follows P * ≤P0. After the BMS obtains the first actual AC power, it sends the first actual AC power to the EMS.

[0104] 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 embodiments of the present application are only exemplary, and can also be carried out in the manner of S102, S103, S101, S104, or can also be carried out in the manner of S104 after S101 and S102, S103 are synchronized.

[0105] The control method of the present application will be introduced below in two levels. Before introducing the control method, the characters appearing below are first defined. Specifically, i: battery stack serial number; j: battery cluster serial number; imax: number of PCSs in parallel; jmax: number of battery clusters in parallel in each battery stack; P ij : power of the jth battery cluster corresponding to the ith PCS; P DC,i: The DC-side power of the i-th PCS; P DG : The power of each other energy power supply system; P AC,i : The AC active power sent by the EMS to the i-th PCS; soc0: The initial soc of the battery cluster; Δsoc0: The maximum initial soc difference between clusters; I ij,pct : The current ratio of the j-th cluster in the i-th stack; Cap ij : The current remaining capacity (chargeable / dischargeable) of the j-th cluster in the i-th stack; C i,min : The remaining working capacity when the system soc converges uniformly obtained by the DC / DC fast distribution algorithm; I ij : The DC current value of the j-th cluster in the i-th stack; I DC,i : The DC bus current of the i-th stack; η i : The working efficiency of the i-th PCS; Cap i : The current remaining capacity (chargeable / dischargeable) of the battery in the i-th stack; U DC,i : The DC voltage of the DC bus of the i-th stack; A: The coefficient matrix of the boundary condition equation system; x: The variable vector to be solved in the boundary condition equation system; b: The constraint condition of the boundary condition equation system; I Bat : The total current of the battery on the DC bus of each stack; I DG : The current of the other energy power supply system on the DC bus of each stack.

[0106] In an optional embodiment, for the first level, determine the current distribution target ratio:

[0107] In S101, the battery cluster parameters refer to the parameters associated with the current distribution of the battery cluster. This parameter can be the attribute characteristics of the battery cluster, such as the current remaining capacity of the battery cluster; this parameter can be a value preset according to the attribute characteristics of the battery cluster, where the preset value can be adjusted in real time and this value is applicable to each battery cluster, such as each battery cluster corresponding to the same capacity setting critical value; this parameter can also be a value calculated according to the attribute characteristics of the battery cluster, such as the distribution ratio constraint interval calculated according to the total number of battery clusters and the overload constraint ratio.

[0108] Here, determine the current distribution target ratio set for each battery cluster according to the battery cluster parameters, and this current distribution target ratio is within the distribution ratio constraint interval. That is, the current distribution target ratio set for each battery cluster can be accurately determined according to the battery cluster parameters. In this way, by distributing current to each battery cluster according to this current distribution target ratio, battery clusters with different capacities can reach equilibrium as soon as possible during operation.

[0109] The above distribution ratio constraint interval is obtained through the following steps:

[0110] S1011. Obtain the total number of battery clusters in a battery energy storage system that are connected in parallel and the overload constraint ratio of the battery energy storage system. The overload constraint ratio represents a preset ratio of the current of the battery cluster exceeding the rated current range during charging or discharging.

[0111] Here, overload means that the battery energy storage system can still operate beyond the rated current range under a certain abnormal state. Among them, the abnormal state refers to the state where the battery energy storage system operates with a cluster missing but maintains a constant power / current output. The overload constraint ratio represents a preset ratio of the current of the battery cluster exceeding the rated current range during charging or discharging. That is to say, the overload constraint ratio represents that the current of the battery cluster during charging is allowed to exceed a preset ratio of the first current specified value or the current of the battery cluster during discharging is allowed to be lower than a preset ratio of the second current specified value. Among them, 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.

[0112] Exemplarily, the range of the overload constraint ratio is between 0 and 1. Specifically, the overload constraint ratio can take a value of 0.1.

[0113] S1012. Determine the upper limit of the distribution ratio constraint and the lower limit of the distribution ratio constraint of the battery energy storage system according to the overload constraint ratio to determine the distribution ratio constraint interval set for each battery cluster.

[0114] Specifically, determine the upper limit of the distribution ratio constraint and the lower limit of the distribution ratio constraint as the two endpoint values of the distribution ratio constraint interval.

[0115] Exemplarily, S1012 specifically includes:

[0116] S1012a. Determine the total value of the upper limit of the distribution ratio constraint and the total value of the lower limit of the distribution ratio constraint of the battery energy storage system according to the overload constraint ratio.

[0117] Here, since the overload constraint ratio is between 0 and 1, the total value of the upper limit of the distribution ratio constraint is the sum of 1 and the overload constraint ratio, and the total value of the lower limit of the distribution ratio constraint is the difference between 1 and the overload constraint ratio.

[0118] S1012b. Use the ratios of the total value of the upper limit of the distribution ratio constraint and the total value of the lower limit of the distribution ratio constraint to the total number of battery clusters respectively to determine the upper limit of the distribution ratio constraint and the lower limit of the distribution ratio constraint set for each battery cluster.

[0119] Here, the distribution ratio constraint intervals of each battery cluster are the same.

[0120] Exemplarily, define the total number of battery clusters as n, the overload constraint ratio as limit, I pct_max represents the upper limit of the distribution ratio, Ipct_min Indicates the lower limit of the allocation ratio constraint; the upper limit I of the allocation ratio constraint pct_max and the lower limit I of the allocation ratio constraint pct_min The calculation formula is as follows:

[0121]

[0122]

[0123] For example, according to the actual configuration parameters of the battery cluster, etc., limit can be set to 0.1, then

[0124]

[0125]

[0126] In the embodiments of the present application, the overload constraint ratio can be adjusted in real time according to the actual operating conditions of the battery cluster, and then the upper limit and lower limit of the allocation ratio constraint can be flexibly set. Within this allocation ratio constraint interval, the current can be allocated according to the target current allocation ratio set for each battery cluster. Since the range of the target current allocation ratio is locked, the stability and reliability of the battery energy storage system can be further increased.

[0127] Furthermore, when the state of charge differences of each battery cluster are too large, there are differences in the target current allocation ratios of each battery cluster, but the differences in the target current allocation ratios are ensured to be within the allocation ratio constraint interval, which can make the state of charge of each battery cluster reach consistency at a faster speed while avoiding the problem of overload of the battery energy storage system caused by external oscillations to the greatest extent, and can achieve balanced management and safe use, further extending the service life of the battery clusters in the battery energy storage system.

[0128] In a preferred embodiment, the battery cluster parameters include the current remaining capacity of the battery cluster and the 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 characterizes the fastest convergence of the state of charge of each battery cluster in the battery energy storage system to consistency. Exemplarily, the capacity setting critical value can be the minimum value of the current remaining capacities of multiple battery clusters.

[0129] Here, a capacity adjustment limit range is set for the capacity setting critical value in advance, and when adjusting the capacity setting critical value, it cannot exceed this capacity adjustment limit range. Specifically, when multiple battery clusters in the battery energy storage system are in the discharge working condition or the charge working condition, the capacity adjustment limit range corresponds to the range between 0 and the capacity setting critical value.

[0130] Among them, determining the target current distribution ratio set for each battery cluster according to the battery cluster parameters specifically includes:

[0131] Step 1021: Determine the first current distribution ratio to be adjusted for each battery cluster according to the current remaining capacity and the capacity setting critical value of each battery cluster.

[0132] Specifically, calculate the capacity difference between the current remaining capacity and the capacity setting critical value of each battery cluster, calculate the sum of the capacity differences corresponding to all battery clusters, for each battery cluster, calculate the ratio between the capacity difference corresponding to this battery cluster and the sum of the capacity differences, and determine this ratio as the first current distribution ratio to be adjusted.

[0133] Exemplarily, define the first current distribution ratio to be adjusted for the i-th battery cluster as I 1i,pct , the capacity setting critical value as min_cap, the current remaining capacity as cap i , and the total number of battery clusters as n; furthermore, the calculation formula for the first current distribution ratio to be adjusted for the i-th battery cluster as I 1i,pct is as follows:

[0134]

[0135] Through the above formula, the first current distribution ratio to be adjusted corresponding to each battery cluster can be calculated, and the purpose of quickly distributing current to the battery cluster can be achieved according to this first current distribution ratio to be adjusted.

[0136] Step 1022: Determine the target current distribution ratio according to whether the first current distribution ratio to be adjusted is within the distribution ratio constraint interval.

[0137] Among them, step 1022 specifically includes:

[0138] 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, then determine the first current distribution ratio to be adjusted within the distribution ratio constraint interval for each battery cluster as the target current distribution ratio corresponding to each battery cluster.

[0139] Here, if the first current distribution ratio to be adjusted corresponding to each battery cluster is within the distribution ratio constraint interval, then the currently calculated first current distribution ratio can be determined as the target current distribution ratio to distribute current to the battery cluster according to this first current distribution ratio to be adjusted.

[0140] Step 1022b: If it is detected that the first to-be-adjusted current allocation ratio set for the battery clusters is not within the allocation ratio constraint interval, then adjust the capacity setting critical value, and re-determine the first to-be-adjusted current allocation ratio set for each battery cluster according to the current remaining capacity of each battery cluster and the adjusted capacity setting critical value until the first to-be-adjusted current allocation ratio re-set for each battery cluster is within the allocation ratio constraint interval. Determine the first to-be-adjusted current allocation ratio within the allocation ratio constraint interval for each battery cluster as the current allocation target ratio corresponding to each battery cluster.

[0141] That is to say, when it is detected that there is a first to-be-adjusted current allocation ratio corresponding to a battery cluster that is not within the allocation ratio constraint interval, the capacity setting critical value can be adjusted. Exemplarily, the capacity setting critical value can be adjusted downward, and then re-calculate the first to-be-adjusted current allocation ratio set for each battery cluster according to the calculation formula of the first to-be-adjusted current allocation ratio in Step 1021 until the capacity setting critical value is adjusted to the minimum value of the capacity adjustment limit range. For example, the minimum value of the capacity adjustment limit range is 0. If, under the condition that the capacity setting critical value is within the capacity adjustment limit range, it is detected that the first to-be-adjusted current allocation ratio corresponding to each battery cluster is within the allocation ratio constraint interval, then the currently determined first to-be-adjusted current allocation ratio can be determined as the current allocation target ratio.

[0142] Step 1023: If it is detected that the adjusted capacity setting critical value is not within the capacity adjustment limit range and there is a first to-be-adjusted current allocation ratio re-set for the battery clusters that is not within the allocation ratio constraint interval, then determine the second to-be-adjusted current allocation ratio set for each battery cluster according to the current remaining capacity of each battery cluster;

[0143] Here, sum up the current remaining capacity of all the battery clusters to obtain the current remaining capacity sum value. For each battery cluster, calculate the ratio between the current remaining capacity corresponding to this battery cluster and the current remaining capacity sum value, and determine this ratio as the second to-be-adjusted current allocation ratio.

[0144] Exemplarily, define the second to-be-adjusted current allocation ratio of the i-th battery cluster as I 2i,pct , and further, the calculation formula for the second to-be-adjusted current allocation ratio of the i-th battery cluster as I 2i,pct is as follows:

[0145]

[0146] Through the above formula, the second to-be-adjusted current allocation ratio corresponding to each battery cluster can be calculated, and the purpose of quickly allocating current to the battery clusters can be achieved according to this second to-be-adjusted current allocation ratio.

[0147] Step 1024: Determine the target current distribution ratio based on whether the second adjustable current distribution ratio is within the distribution ratio constraint range.

[0148] Among them, Step 1024 specifically includes:

[0149] Step 1024a: If it is detected that the second adjustable current distribution ratio set for each battery cluster is within the distribution ratio constraint range, then determine the second adjustable current distribution ratio of each battery cluster within the distribution ratio constraint range as the corresponding target current distribution ratio of each battery cluster.

[0150] Here, if the second adjustable current distribution ratio corresponding to each battery cluster is within the distribution ratio constraint range, then the currently calculated second adjustable current distribution ratio can be determined as the target current distribution ratio to distribute current to the battery clusters according to this second adjustable current distribution ratio.

[0151] Step 1024b: If it is detected that the second adjustable current distribution ratio set for the battery cluster is not within the distribution ratio constraint range, then respectively determine the number of the first battery clusters corresponding to the battery clusters with the second adjustable current distribution ratio greater than the upper limit of the distribution ratio constraint and the number of the second battery clusters corresponding to the battery clusters with the second adjustable current distribution ratio less than the lower limit of the distribution ratio constraint.

[0152] Among them, the battery cluster parameters include the distribution ratio constraint range, and the distribution ratio constraint range includes the upper limit of the distribution ratio constraint and the lower limit of the distribution ratio constraint. The number of the first battery clusters can be determined according to the upper limit of the distribution ratio constraint, and the number of the second battery clusters can be determined according to the lower limit of the distribution ratio constraint.

[0153] Step 1024c: Determine the distribution ratio adjustment value for adjusting the second adjustable current distribution ratio that is not within the distribution ratio constraint range to the closest upper limit or lower limit of the distribution ratio constraint, so as to obtain the total distribution ratio adjustment value corresponding to all the battery clusters with the second adjustable current distribution ratio not within the distribution ratio constraint range.

[0154] Among them, the distribution ratio adjustment value for adjusting the second adjustable current distribution ratio less than the lower limit of the distribution ratio constraint to the lower limit of the distribution ratio constraint is negative, and the distribution ratio adjustment value for adjusting the second adjustable current distribution ratio greater than the upper limit of the distribution ratio constraint to the upper limit of the distribution ratio constraint is positive.

[0155] Here, calculate the difference between the second current allocation ratio to be adjusted and the closest upper limit or the closest lower limit of the allocation ratio constraint. This difference is the allocation ratio adjustment value. Specifically, this difference can be positive or negative. When subtracting the lower limit of the allocation ratio constraint from the second current allocation ratio to be adjusted that is less than the lower limit of the allocation ratio constraint, the obtained allocation ratio adjustment value is negative; when subtracting the upper limit of the allocation ratio constraint from the second current allocation ratio to be adjusted that is greater than the upper limit of the allocation ratio constraint, the obtained allocation ratio adjustment value is positive. Sum up the allocation ratio adjustment values corresponding to all battery clusters whose second current allocation ratios to be adjusted are not within the allocation ratio constraint interval to obtain the total allocation ratio adjustment value. Here, since the allocation ratio adjustment value can be positive or negative, the calculated total allocation ratio adjustment value can be positive or negative.

[0156] Step 1025: Determine the target current allocation ratio according to the magnitude relationship between the total allocation ratio adjustment value and the preset allocation ratio adjustment threshold.

[0157] Among them, Step 1025 specifically includes:

[0158] Step 1025a: If the total allocation ratio adjustment value is less than or equal to the preset allocation ratio adjustment threshold, then determine the target current allocation ratio for the battery clusters whose second current allocation ratios to be adjusted are not within the allocation ratio constraint interval according to the lower limit of the allocation ratio constraint, the total allocation ratio adjustment value, and the number of the second battery clusters, and determine the target current allocation ratio for the battery clusters whose second current allocation ratios to be adjusted are within the allocation ratio constraint interval according to the current remaining capacity of the battery clusters.

[0159] Exemplarily, the preset allocation ratio adjustment threshold can be 0. For the second current allocation ratios to be adjusted corresponding to each battery cluster calculated in Step 1023, there are some or all battery clusters whose second current allocation ratios to be adjusted are not within the allocation ratio constraint interval. Then, for the battery clusters whose second current allocation ratios to be adjusted are not within the allocation ratio constraint interval, use the new calculation method involved in Step 1025 to calculate the target current allocation ratio, and for the battery clusters whose second current allocation ratios to be adjusted are within the allocation ratio constraint interval, continue to use the calculation method involved in Step 1023 to calculate the target current allocation ratio.

[0160] Here, if the total allocation ratio adjustment value is less than or equal to the preset allocation ratio adjustment threshold, then for the battery clusters whose second current allocation ratios to be adjusted are not within the allocation ratio constraint interval, use the following calculation method to determine the target current allocation ratio:

[0161] Adjust the ratio between the total value and the number of the second battery clusters using the allocation ratio to determine the average value of the allocation ratio adjustment; use the sum value between the lower limit of the allocation ratio constraint and the average value of the allocation ratio adjustment to determine the current allocation target ratio for the battery clusters whose second current to be adjusted is not within the allocation ratio constraint interval.

[0162] Exemplarily, define the current allocation target ratio of the i-th battery cluster as I 32i,Pct , the number of the second battery clusters is n2, the total value of the allocation ratio adjustment is Vol. Further, the current allocation target ratio I 32i,pct of the i-th battery cluster is calculated as follows:

[0163]

[0164] Step 1025b: If the total value of the allocation ratio adjustment is less than or equal to the preset allocation ratio adjustment threshold, determine the current allocation target ratio for the battery clusters whose second current to be adjusted is not within the allocation ratio constraint interval according to the upper limit of the allocation ratio constraint, the total value of the allocation ratio adjustment, and the number of the first battery clusters, and determine the current allocation target ratio for the battery clusters whose second current to be adjusted is within the allocation ratio constraint interval according to the current remaining capacity of the battery clusters.

[0165] Here, if the total value of the allocation ratio adjustment is less than or equal to the preset allocation ratio adjustment threshold, for the battery clusters whose second current to be adjusted is not within the allocation ratio constraint interval, the following calculation method is used to determine the current allocation target ratio:

[0166] Adjust the ratio between the total value of the allocation ratio adjustment and the number of the first battery clusters to determine the average value of the allocation ratio adjustment; use the sum value between the upper limit of the allocation ratio constraint and the average value of the allocation ratio adjustment to determine the current allocation target ratio for the battery clusters whose second current to be adjusted is not within the allocation ratio constraint interval.

[0167] Exemplarily, define the current allocation target ratio of the i-th battery cluster as I 31i,pct , the number of the first battery clusters is n1, the total value of the allocation ratio adjustment is Vol. Further, the current allocation target ratio I 31i,pct of the i-th battery cluster is calculated as follows:

[0168]

[0169] It should be noted that when the second current to be adjusted is not within the allocation ratio constraint interval, according to the magnitude relationship between the total value of the allocation ratio adjustment and the preset allocation ratio adjustment threshold, directly calculate the current allocation target ratio through Step 1025a or Step 1025b.

[0170] Step 1025c: If the current distribution target ratio set for a battery cluster whose second to-be-adjusted current distribution ratio is not within the distribution ratio constraint interval is not within the distribution ratio constraint interval, recalculate the total adjustment value of the distribution ratio corresponding to all battery clusters whose current distribution target ratios are not within the distribution ratio constraint interval;

[0171] Detect the magnitude relationship between the recalculated total adjustment value of the distribution ratio and the preset distribution ratio adjustment threshold, and loop to execute Step 1025a and / or Step 1025b until the new current distribution target ratio newly set for each battery cluster whose current distribution target ratio is not within the distribution ratio constraint interval is within the distribution ratio constraint interval.

[0172] The current distribution target ratio finally obtained through Step 1025c can be guaranteed to be within the distribution ratio constraint interval, and there is no need to perform further calculations by other means.

[0173] Through the above method, different calculation methods can be used to determine the current distribution target ratio under different parameter conditions. In this way, the current can be accurately distributed to each battery cluster according to the current distribution target ratio, so that battery clusters with different capacities can reach equilibrium as soon as possible during operation.

[0174] In the embodiment of the present application, there are also cases where the system parameters of the battery energy storage system do not meet the current equalization condition. For such cases, the following steps are taken for processing:

[0175] S201: Under the condition that the system parameters of the battery energy storage system do not meet the current equalization condition, determine the distribution ratio constraint interval set for each battery cluster according to the total number of battery clusters in the battery energy storage system that are connected in parallel;

[0176] S202: Determine the current distribution target ratio set for each battery cluster according to the battery cluster parameters; among them, 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; distribute current to each battery cluster according to the current distribution target ratio;

[0177] S203: Under the condition that the system parameters of the battery energy storage system meet the current equalization condition, determine the current equalization ratio set for each battery cluster according to the total number of battery clusters; distribute current to each battery cluster according to the current equalization ratio.

[0178] Among them, the description of S202 can refer to the above embodiment and will not be elaborated here.

[0179] In S201, the current sharing condition includes one of the following items: the battery energy storage system is in a stationary 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.

[0180] Among them, the battery management system (BMS) counts 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 the system operating conditions, etc. Among them, the system operating conditions include stationary conditions, charging conditions, or discharging conditions. It is determined whether the system parameters of the battery energy storage system meet the current sharing condition according to the above data counted by the BMS.

[0181] Exemplarily, in order to prevent the capacity difference between the current remaining capacities of the battery clusters in the battery energy storage system from being too large, a relatively small value, such as 1%, is selected for the preset difference threshold.

[0182] Here, when the system parameters of the battery energy storage system do not meet the above current sharing condition, the 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. The specific implementation method can refer to S101 and will not be elaborated here.

[0183] 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; the current is allocated to each battery cluster according to the current sharing ratio.

[0184] That is to say, when the battery energy storage system is in a stationary 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, exemplarily, the first preset ratio is 10%, the second preset ratio is 90%, and the state of charge difference is less than the 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, the current sharing ratio set for each battery cluster is directly determined according to the total number of battery clusters.

[0185] Exemplarily, the current sharing ratio is determined by the following formula:

[0186]

[0187] Among them, n represents the total number of battery clusters.

[0188] 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.

[0189] In the embodiment of the present application, the constraint interval of the distribution ratio set for each battery cluster is first defined. In this way, regardless of whether the difference in the initial state of charge of each battery cluster is too large, it is possible to control the target current distribution ratio set for each battery cluster within the distribution ratio constraint interval, avoiding too large a difference in the target current distribution ratio of each battery cluster in the case of too large a difference in the initial state of charge. This can not only make the state of charge of each battery cluster reach agreement more quickly, but also avoid the problem that the oscillation caused outside the battery energy storage system is likely to cause the battery energy storage system to be overloaded when the difference in the current distribution ratio is large. Then, according to the battery cluster parameters, the target current distribution ratio set for each battery cluster is determined. 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. The DC converter in the battery energy storage system can accurately distribute current to each battery cluster according to the target current distribution ratio in the above manner, and the target current distribution ratio can be configured as the limit ratio within the distribution ratio constraint interval, so that the DC converter charges and discharges with the allowable limit current, thereby ensuring that battery clusters with different capacities can quickly reach equilibrium during operation, achieving the effect of increasing the stability and reliability of the battery energy storage system.

[0190] In an optional embodiment, for the second layer, the AC active power of each battery stack is calculated: In order to calculate the AC active power of each battery stack, in the embodiment of the present application, the DC active power of each battery stack is first calculated, and then through conversion of the active power, the AC active power of the battery stack is obtained.

[0191] When calculating the DC active power of the battery stack, the main basis in the embodiment of the present application is the preset first constraint condition. Here, 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.

[0192] The current remaining capacity of the battery stack here is the sum of the current remaining capacities of each battery cluster in the battery stack, and can be specifically calculated in the following manner:

[0193]

[0194] In specific implementation, the reference ratio in the embodiments of the present application can be represented by the DC bus current, that is, the DC bus current is the ratio of the DC active power to the DC voltage. Furthermore, the current remaining capacity of any battery stack in the embodiments of the present application is positively correlated with the DC bus current of that battery stack. Based on the positive correlation between the current remaining capacity of any battery stack and the DC bus current of that battery stack, the current remaining capacities of each battery stack are obtained in the embodiments of the present application. By comparing the relative current remaining margins, the relative ratio between the DC bus currents can be obtained. For the sake of distinction, in the embodiments of the present application, the relative ratio of the current remaining capacities between each battery stack is called the first relative ratio, and the relative ratio between the reference ratios (i.e., the DC bus currents) of each battery stack is called the second relative ratio. Specifically:

[0195] I DC,1 :I DC,2 :…:I DC,i =Cap1:Cap2:…:Cap i

[0196] The positive correlation between the current remaining capacity of any battery stack and the DC bus current of that battery stack in the embodiments of the present application is determined by the connection relationship of the battery energy storage system in the embodiments of the present application. In the battery energy storage system in the embodiments of the present application, since each battery stack is independent and has an independent thermal management system. Therefore, only the situation where different battery stacks are fully charged or fully discharged simultaneously during parallel operation is considered. The excessive difference in the DC bus current within the allowable range of the maximum power will not affect the battery consistency. To achieve simultaneous full charge or full discharge of the battery stacks, the DC bus current ratio is determined by the capacity.

[0197] After determining the second relative ratio between the DC bus currents of each battery stack, and then combining the DC voltage obtained in the embodiments of the present application, after combining the DC voltage of each battery stack with the second relative ratio of that battery stack, the ratio between the DC active powers of each battery stack can be calculated. Then, 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 can be 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 that battery stack.

[0198] In an optional embodiment, due to factors such as power loss during power usage, to improve the accuracy, the embodiments of the present application also need to consider the actual working efficiency of the PCS. That is to say, 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 sum of the DC active powers (P AC,i multiplied by η i ) of each battery stack at the actual working efficiency. When converting the DC active power, it is also necessary to consider the actual working efficiency of the PCS and perform the conversion based on the working efficiency.

[0199] To improve the efficiency of calculating the above DC active power, the embodiments of the present application adopt the method of constructing a matrix operation formula. Specifically: taking 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 as known quantities, and the DC active powers of each battery stack as variables to be solved, based on the power balance principle, construct a first matrix operation formula; solve the first matrix operation formula to obtain the DC active powers of each battery stack.

[0200] The specifically constructed first matrix operation formula is: the product of a first known matrix and a first matrix to be solved is equal to a second known matrix. Among them, based on the second relative ratio between the reference ratios of each battery stack, the DC voltage of each bidirectional energy storage converter, and the working efficiency, construct the first known matrix; based on the first actual AC power, construct the second known matrix; based on the DC active powers of each battery stack, construct the first matrix to be solved.

[0201] In specific implementation, first, the BMS is used to collect and convert to obtain the maximum power PO of the battery system. Specifically:

[0202]

[0203] The actual charge-discharge operating power P* of the energy storage battery system needs to be manually set, or obtained from a grid dispatching instruction or an optimization algorithm, but it must satisfy:

[0204] P * ≤P0

[0205] The power balance principle in this embodiment can be expressed as:

[0206]

[0207] The first matrix operation formula constructed based on this power balance principle is: A * x = b; specifically:

[0208]

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

[0210] For the conversion of the AC active power of each of the battery stacks, it can be carried out in the following manner:

[0211]

[0212] In an alternative embodiment, there may also be a situation where the battery energy storage system in the embodiments of the present application is AC-coupled with other energy power supply systems. The connection method is as Figure 4 shown, and the other energy power supply systems are connected in parallel on the AC side of the PCS. There may also be a situation where the battery energy storage system in the embodiments of the present application is DC-coupled with other energy power supply systems. The connection method is as Figure 5 shown: Each other energy power supply system is separately connected in parallel to each DC bus and then inverted to the AC side through the PCS. Therefore, the efficiency corresponding to each DC energy power supply system should be consistent with the AC-DC conversion efficiency of the energy storage system, which is determined by the PCS. For this situation, when calculating the AC active power of each of the battery stacks in the embodiments of the present application, it is necessary to exclude the DC current of the other energy power supply systems. The biggest difference between this and the above embodiment lies in the constraint conditions and the considered parameters. For the purpose of distinction, the constraint conditions here are called the second constraint conditions. The second constraint condition is specifically 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 to the DC voltage. The considered parameters are mainly reflected in the second actual AC power of other DC power supply systems.

[0213] Here, the ratio of the DC active power of the battery stack to the DC voltage can still be represented by the DC bus current (I DC,i ) of each DC bus in the above embodiment. The ratio of the DC active power of other DC energy to the DC voltage can be represented by the DC current (I DG ) of each other energy power supply system. In the embodiments of the present application, the current remaining capacity of each battery stack is obtained. By comparing the current remaining margins with each other, the relative ratio between the difference between the DC bus current and the DC current of other energy power supply systems can be obtained. For the purpose of distinction, the relative ratio between the relative differences is called the third relative ratio.

[0214] 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 the battery stacks obtained, the third relative ratio between the relative differences here is obtained. Specifically, it can be represented by the following formula:

[0215]

[0216] It can also be specifically embodied as:

[0217]

[0218] After determining the third relative comparison between the relative differences, and then combining the DC voltage obtained in the embodiments of the present application, after combining the DC voltage of each battery stack with the third relative comparison of this battery stack, the ratio between the DC active powers of each battery stack can be calculated, that is, the ratio between the DC active powers of each battery stack can be calculated. Then, in combination 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 comparison 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 this battery stack.

[0219] In an optional implementation manner, due to factors such as power loss during the use of electric energy, in order to improve the accuracy, the embodiments of the present application also need to consider the actual working efficiency of the PCS. That is to say, 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 sum of the DC active powers (P AC,i multiplied by η i ) of each battery stack under the actual working efficiency. When converting the DC active power, it is also necessary to consider the actual working efficiency of the PCS and perform the conversion based on the working efficiency.

[0220] In order to improve the efficiency of calculating the above DC active power, the embodiments of the present application adopt the method of constructing a matrix operation formula. Specifically: taking the third relative comparison, 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 as known quantities, and the DC active power of each battery stack as the variable to be solved, based on the power balance principle, construct a second matrix operation formula; solve the second matrix operation formula to obtain the DC active power of each battery stack.

[0221] The specifically constructed second matrix operation formula is as follows: The product of a third known matrix and a second matrix to be solved is equal to a fourth known matrix. Among them, the third known matrix is constructed based on the third comparison between the reference differences of each battery stack, the DC voltage and operating efficiency of each bidirectional energy storage converter; 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 solved is constructed based on the DC active power of each battery stack and the DC active power of each other DC energy system.

[0222] In specific implementation, the power balance principle in this embodiment can be expressed as:

[0223]

[0224] The second matrix operation formula constructed based on this power balance principle is: A * x = b; specifically:

[0225]

[0226] Among them, the variable to be solved: x = A -1 * b. By solving for x, the AC active power of each battery stack can be obtained.

[0227] For the conversion of the AC active power of each battery stack, it can be carried out in the following manner:

[0228]

[0229] In this application, the calculation method of AC coupling between the battery energy storage system and other energy power supply systems is the same as that of DC coupling with other energy power supply systems, which will not be elaborated here.

[0230] In this application, under the grid-connected PQ control mode of the PCS, the remaining available capacity Cap of all battery stacks is used i to calculate the corresponding DC bus current ratio of each stack, and the total power of the energy storage system is calculated by summarizing the minimum power of each stack reported by the BMS to the EMS. Without affecting the charge and discharge power of the energy storage system, the active power set value of each PCS is adjusted. Considering the different operating efficiencies of each PCS and the inconsistency of the DC bus voltage caused by the inconsistency of the batteries themselves, the DC bus current is reasonably and accurately allocated and controlled to achieve the state of full charge or full discharge between stacks at the same time, ensuring the charge and discharge depth of the entire system. At the same time, a large difference in the DC bus current between different PCSs is allowed because each stack has an independent thermal management system, and a large difference in the operating current will not cause a large difference in consistency between battery clusters.

[0231] Meanwhile, by reasonably allocating the current ratio for each different battery cluster, the different available capacities soc of different battery clusters within the same battery stack can converge quickly and consistently with the maximum capacity within the allowable working current range under the DC / DC and the allocated current ratio, reducing the capacity and soc differences between different battery clusters within the same battery stack.

[0232] On the one hand, this application controls the active power setting of each PCS to control the DC bus current of each branch, enabling each battery stack to reach full charge or full discharge simultaneously. On the other hand, it cooperates with the DC / DC current distribution algorithm to allocate the current ratio of the battery clusters within the same stack, reducing system differences and greatly improving the consistency, lifespan, working efficiency, and charge-discharge depth of the entire energy storage system.

[0233] Figure 6 The figure shows a schematic structural diagram of a control device provided by an embodiment of this application, 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 the AC grid through the DC power converter and the bidirectional energy storage converter corresponding to this battery cluster; the energy storage manager is respectively connected to each DC power converter and the bidirectional energy storage converter by signals; the device includes:

[0234] A determination module, configured to determine the current distribution target ratio set for each battery cluster according to the battery cluster parameters of each battery cluster in each battery stack.

[0235] An acquisition module, configured to acquire 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.

[0236] A calculation module, configured to calculate the AC active power of each battery stack according to the acquired first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint condition.

[0237] A control module, configured to send the AC active power to the corresponding bidirectional energy storage converter to adjust the current allocated by each bidirectional energy storage converter, and control each DC power converter based on the current distribution target ratio to adjust the current allocated to each battery cluster.

[0238] Calculating the AC active power of each battery stack according to the acquired first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint condition includes:

[0239] 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, calculate the DC active power of the battery stack;

[0240] According to the DC active power of the battery stack and the operating efficiency of each bidirectional energy storage converter, calculate the AC active power of each battery stack.

[0241] The first constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference ratio of that battery stack; the reference ratio is the ratio of the DC active power of the battery stack to the DC voltage.

[0242] 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:

[0243] Based on the fact that the current remaining capacity of any battery stack is positively correlated with the reference ratio of that battery stack, according to the first relative ratio of the current remaining capacity between each battery stack, determine the second relative ratio between the reference ratios of each battery stack;

[0244] 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, calculate the DC active power of each battery stack.

[0245] The calculating the DC active power of each battery stack 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:

[0246] Based on the power balance principle, construct a first matrix operation formula; 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 the variable to be solved;

[0247] Solve the first matrix operation formula to obtain the DC active power of each battery stack.

[0248] The first matrix operation formula includes a first known matrix, a second known matrix, and a first matrix to be solved; the constructing the first matrix operation formula based on the power balance principle includes:

[0249] According to the second relative ratio between the reference ratios of each battery stack, the DC voltage and the operating efficiency of each bidirectional energy storage converter, construct the first known matrix;

[0250] Construct the second known matrix according to the first actual AC power;

[0251] Construct the first matrix to be solved according to the DC active power of each battery stack;

[0252] The product of the first known matrix and the first matrix to be solved is equal to the second known matrix.

[0253] 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 bi-directional energy storage converter includes:

[0254] Determine the conversion ratio corresponding to the DC active power of the bi-directional energy storage converter according to the working efficiency of each bi-directional energy storage converter;

[0255] Convert the DC active power of the bi-directional energy storage converter into the AC active power of the battery stack according to the conversion ratio.

[0256] The power balance 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 powers of each battery stack.

[0257] Obtain the first actual AC power of all battery stacks in the following way:

[0258] The energy storage manager obtains the sub-AC power of each battery stack;

[0259] Pool all the sub-AC powers together to obtain the first total power of all battery stacks;

[0260] Obtain the first actual AC power by performing actual loss removal processing on the first total power.

[0261] The bi-directional energy storage converter is also connected to other energy supply systems;

[0262] Calculate the AC active power of each battery stack in the following way, including:

[0263] The energy storage manager calculates the AC active power of each battery stack according to the preset second constraint conditions, based on the obtained first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity, and the DC voltage.

[0264] The energy storage manager calculates the AC active power of each battery stack according to the preset second constraint conditions, based on the obtained first actual AC power, the second actual AC power of other DC energy systems, the current remaining capacity, and the DC voltage, including:

[0265] Based on the power balance principle, calculate the DC active power of the battery stack 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;

[0266] Calculate 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.

[0267] The second constraint condition is that the current remaining capacity of any battery stack is positively correlated with the reference difference value of the battery stack; the reference difference value 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 to the DC voltage.

[0268] The method of calculating the DC active power of the battery stack 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 condition includes:

[0269] Based on the positive correlation between the current remaining capacity of the battery stack and the reference difference value of the battery stack, calculate the third relative ratio between the reference difference values of each battery stack according to the first relative ratio between the current remaining capacities of each battery stack;

[0270] Based on the power balance principle, calculate the DC active power of each battery stack 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.

[0271] 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:

[0272] Based on the power balance principle, construct a second matrix operation formula; 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 the variable to be solved;

[0273] Solve the second matrix operation formula to obtain the DC active power of each battery stack.

[0274] The second matrix operation expression includes a third known matrix, a fourth known matrix, and a second matrix to be solved; constructing the second matrix operation expression based on the power balance principle includes:

[0275] Construct the third known matrix according to the third relative comparison between the reference differences of each battery stack, the DC voltage and working efficiency of each bidirectional energy storage converter;

[0276] Construct 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;

[0277] Construct 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 system;

[0278] The product of the third known matrix and the second matrix to be solved is equal to the fourth known matrix.

[0279] 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:

[0280] Determine 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;

[0281] Convert the DC active power of the bidirectional energy storage converter into the AC active power of the battery stack according to the conversion ratio.

[0282] 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.

[0283] 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 according to the total number of battery clusters connected in parallel in the battery energy storage system.

[0284] Determining the distribution 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:

[0285] When the system parameters of the battery energy storage system do not meet the current equalization condition, determine the distribution 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.

[0286] Determining the allocation ratio constraint interval set for each battery cluster according to the total number of battery clusters in a battery energy storage system connected in parallel includes:

[0287] Obtaining the total number of battery clusters in a 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;

[0288] According to the overload constraint ratio, determining the upper limit and lower limit of the allocation ratio constraint of the battery energy storage system to determine the allocation ratio constraint interval set for each battery cluster.

[0289] 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.

[0290] Determining the target current allocation ratio set for each battery cluster according to the battery cluster parameters includes:

[0291] According to the current remaining capacity of each battery cluster and the capacity setting critical value, determining the first to-be-adjusted current allocation ratio set for each battery cluster;

[0292] Determining the target current allocation ratio according to whether the first to-be-adjusted current allocation ratio is within the allocation ratio constraint interval.

[0293] 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.

[0294] As Figure 7 shown, an embodiment of the present application provides an electronic device for executing the control method in the present application. The device includes a memory, a processor, a bus, and a computer program stored on the memory and executable on the processor. Wherein, when the above-mentioned processor executes the above-mentioned computer program, the steps of the above-mentioned control method are implemented.

[0295] Specifically, the above-mentioned memory and processor can be general memory and processor, which are not specifically limited here. When the processor runs the computer program stored in the memory, it can execute the above-mentioned control method.

[0296] Corresponding to the control method in this application, an embodiment of this application also provides a computer-readable storage medium. A computer program is stored on this computer-readable storage medium. When the computer program is run by a processor, it executes the steps of the above-mentioned control method.

[0297] Specifically, this storage medium can be a general storage medium, such as a removable disk, a hard disk, etc. When the computer program on this storage medium is run, it can execute the above-mentioned control method.

[0298] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. The system embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For another example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some communication interfaces. The indirect coupling or communication connection of the system or unit can be in an electrical, mechanical or other form.

[0299] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units. They can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0300] In addition, each functional unit in the embodiments provided in this application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0301] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art or part of this technical solution can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable 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 methods described in various embodiments of this application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0302] It should be noted that like reference numerals and letters indicate like 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 for descriptive distinction and should not be construed as indicating or implying relative importance.

[0303] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present application, used to illustrate the technical solutions of the present application, rather than limiting it. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the art within the technical scope disclosed in the present application can still modify the technical solutions described in the foregoing embodiments or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application. All should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A control method, characterized in that, Acting on a battery energy storage system, the battery energy storage system 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 corresponding to the battery cluster and the bidirectional energy storage converter; the energy storage manager is respectively signal-connected to each DC power converter and the bidirectional energy storage converter; 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 issues 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, according to the first actual AC power, the current remaining capacity, the DC voltage, and the first constraint condition, calculate the DC active power of the battery stack; According to the DC active power of the battery stack and the working efficiency of each bidirectional energy storage converter, calculate the AC active power of each of the battery stacks.

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, wherein 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 fact that the current remaining capacity of any battery stack is positively correlated with 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, 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, calculate the DC active power of each of the battery stacks.

5. The method according to claim 4, characterized in that, 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; 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, wherein 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, wherein 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, calculating the third relative ratio between the reference differences of each battery stack according to the first relative ratio between the current remaining capacities 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, characterized in that, 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, wherein 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 converters; 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 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 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 bidirectional energy storage converter in a 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 the acquired first actual AC power, the current remaining capacity, and the DC voltage according to a preset first constraint condition; A control module, configured 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 control each DC power converter based on the current allocation target ratio to adjust the current allocated to 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.

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