Energy storage system and control method therefor

Abstract

The present application relates to the technical field of energy storage. Specifically disclosed are an energy storage system and a control method therefor. The energy storage system comprises a plurality of branches. The control method for the energy storage system comprises: acquiring a power-on request; in response to the power-on request, acquiring state information of all battery clusters on each branch, wherein the state information at least comprises an internal sampling voltage; and for any branch, on the basis of the state information of all the battery clusters on the branch, sending a power-on instruction to one of the battery clusters on the branch or to a plurality of voltage-equalized battery clusters on the branch, wherein the power-on instruction is used for instructing the corresponding battery cluster to execute a power-on operation. By means of the control method of the present invention, there is one battery cluster or a plurality of voltage-equalized battery clusters on each branch to implement a power-on process, such that all the branches can be powered on. Compared with the relevant art in which some branches cannot be powered on, the control method can increase the external discharge capacity of the energy storage system. Moreover, the possibility of the battery clusters on the branches being damaged due to the generation of a circulating current on the branches can be reduced.

Description

Energy storage system and control method thereof

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202411021343.6, filed on July 29, 2024, entitled “Energy storage system and control method thereof”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of energy storage, and in particular to an energy storage system and a control method thereof. BACKGROUND

[0004] An energy storage system stores excess electrical energy when there is an excess of energy supply through a medium or device, and releases the stored energy when there is a shortage of energy supply, thereby solving the problems of grid volatility and unstable supply. When the energy storage system is composed of multiple branches and each branch includes multiple battery clusters, if the difference between the internal sampling voltages of each battery cluster is large, in order to reduce the possibility of circulating current between each battery cluster and damaging the battery cluster, part of the branches are not powered on, resulting in low external discharge capacity of the energy storage system. SUMMARY

[0005] In view of the above problems, the present application provides an energy storage system and a control method thereof, which solves the problem of low external discharge capacity of the energy storage system caused by the fact that part of the branches are not powered on.

[0006] A first aspect of the present application provides a control method of an energy storage system, the energy storage system comprising N branches and at least one energy storage converter, each branch being provided with a plurality of battery clusters independent of each other, a battery cluster comprising at least one battery pack, N being a positive integer greater than or equal to 2, each energy storage converter being electrically connected to K branches, and each branch being capable of charging or discharging through the corresponding energy storage converter, K being a positive integer, K being greater than or equal to 2 and less than or equal to N, and the K branches being connected in parallel when K is greater than or equal to 2 and less than or equal to N.

[0007] The control method of the energy storage system comprises:

[0008] obtaining a power-on request;

[0009] in response to the power-on request, obtaining state information of all battery clusters in each branch, the state information at least including an internal sampling voltage; and

[0010] For any branch of the N branches, based on the state information of all battery clusters on the branch, an upper power instruction is sent to one of the battery clusters on the branch or to M battery clusters on the branch that satisfy voltage balance, M is a positive integer greater than or equal to 2, and the voltage balance means that the difference between the internal sampling voltage of the remaining battery clusters and the reference voltage, which is the voltage value related to one of the M battery clusters, is less than a first threshold value, and the upper power instruction is used to instruct the corresponding battery cluster to perform the upper power operation.

[0011] In the present application, each branch independently performs the upper power flow in response to the upper power request, and the upper power logic of each branch does not affect each other. Moreover, for any branch, when there is voltage balance of M battery clusters, the upper power control of the M battery clusters is realized, and when the voltage of any two battery clusters is not balanced, the upper power control of one battery cluster is realized. In this way, at least one battery cluster on each branch performs the upper power operation, so that the N branches can all realize the upper power. Compared with the related art in which part of the branches cannot be powered on, the external discharge capacity of the energy storage system can be improved. At the same time, the possibility of generating circulating current on the branch and damaging the battery cluster on the branch is reduced as much as possible.

[0012] In some embodiments of the present application, for any branch of the N branches, based on the state information of all battery clusters on the branch, an upper power instruction is sent to one of the battery clusters on the branch or to M battery clusters on the branch that satisfy voltage balance, including:

[0013] For any branch of the N branches, based on the state information of all battery clusters on the branch, a first battery cluster is determined among all the battery clusters;

[0014] An upper power instruction is sent to the first battery cluster;

[0015] In the case that the first battery cluster is successfully powered on, it is confirmed whether there is a second battery cluster on the branch, the second battery cluster is in voltage balance with the first battery cluster, and the reference voltage is related to the first battery cluster;

[0016] In response to the existence of the second battery cluster on the branch, an upper power instruction is sent to the second battery cluster.

[0017] In the present embodiment, a single battery cluster (i.e. the first battery cluster) on each branch is first caused to perform the upper power operation, so that circulating current is not generated in the single battery cluster upper power stage. In the case that the first battery cluster is successfully powered on, in the second battery cluster upper power stage, since the first battery cluster and the second battery cluster are in voltage balance, the possibility of generating circulating current between the first battery cluster and the second battery cluster is still low, which is conducive to improving the operation stability of the energy storage system.

[0018] In some embodiments of the present application, the state information further includes an external sampling voltage;

[0019] In a case that the first battery cluster is successfully powered on, it is determined whether there is a second battery cluster on the branch, the second battery cluster is voltage balanced with the first battery cluster, and the reference voltage is related to the first battery cluster, specifically comprising:

[0020] In a case that the first battery cluster is successfully powered on, the reference voltage is obtained, and the reference voltage is an external sampling voltage of the first battery cluster;

[0021] It is determined whether an absolute value of a difference between an internal sampling voltage of a battery cluster and the reference voltage is less than a first threshold value among the remaining battery clusters on the branch;

[0022] Based on the determination result, it is determined whether there is a second battery cluster.

[0023] By designing the second battery cluster to satisfy that an absolute value of a difference between the internal sampling voltage and the external sampling voltage of the first battery cluster is less than the first threshold value, the internal sampling voltage of the screened second battery cluster is balanced with the external sampling voltage of the first battery cluster that is successfully powered on, so that the risk of the second battery cluster and the energy storage converter being too large in pressure difference and causing high pressure impact on the energy storage converter can be more accurately reduced.

[0024] In some embodiments of the present application, each branch is provided with at least three battery clusters;

[0025] The first battery cluster is determined among all battery clusters, specifically comprising:

[0026] The battery cluster with the internal sampling voltage arranged in the middle position is determined as the first battery cluster among all battery clusters.

[0027] Designing the first battery cluster as the battery cluster with the internal sampling voltage arranged in the middle position can increase the number of second battery clusters, thereby facilitating to increase the number of battery clusters performing power-on operation on the branch, facilitating to increase the possibility of each branch achieving power-on, and facilitating to increase the external discharge power of the energy storage system.

[0028] In some embodiments of the present application, the state information further comprises fault information;

[0029] The power-on instruction is sent to one of the battery clusters on the branch or to the M battery clusters on the branch that satisfy voltage balance, specifically comprising:

[0030] The power-on instruction is sent to one of the battery clusters on the branch that satisfies the allowed power-on condition, or the power-on instruction is sent to the M battery clusters on the branch that satisfy the allowed power-on condition and voltage balance; wherein the allowed power-on condition comprises a fault level lower than a first set level.

[0031] By designing to send the power-up instruction to the battery cluster meeting the allowed power-up condition on the branch, the battery cluster receiving the power-up instruction to perform the power-up operation should meet the premise of meeting the allowed power-up condition, so that the power-up instruction does not need to be sent to the battery cluster not meeting the allowed power-up condition, which is beneficial to simplify the control process of the energy storage system.

[0032] In some embodiments of the present application, the power-up time of the battery cluster is timed while sending the power-up instruction to any one of the battery clusters;

[0033] In response to the battery cluster completing the power-up operation within the first preset time, it is confirmed that the battery cluster is successfully powered up.

[0034] By setting the first preset time as a threshold to confirm whether the power-up time of the battery cluster is too long, the power-up time of the battery cluster successfully powered up does not exceed the first preset time, and the function of the battery cluster successfully powered up is normal, so that the possibility of causing failure or even accident by powering up the battery cluster not in normal function can be reduced.

[0035] In some embodiments of the present application, the state information further includes an external sampling voltage;

[0036] The power-up instruction is configured to instruct the pre-charging circuit of the corresponding battery cluster to be powered up, and to obtain the pre-charging time, the internal sampling voltage and the external sampling voltage of the battery cluster;

[0037] The power-up instruction is configured to instruct the pre-charging circuit of the corresponding battery cluster to be powered up, and to obtain the pre-charging time, the internal sampling voltage and the external sampling voltage of the battery cluster;

[0038] The power-up instruction is configured to instruct the pre-charging circuit of the corresponding battery cluster to be powered up, and to obtain the pre-charging time, the internal sampling voltage and the external sampling voltage of the battery cluster;

[0039] In this embodiment, the battery cluster is powered up to pre-charge before the main circuit is powered up, which is beneficial to reduce the risk of high voltage impact on the energy storage converter caused by excessive voltage difference between the battery cluster and the energy storage converter.

[0040] In some embodiments of the present application, after sending the power-up instruction to one battery cluster or to M battery clusters for voltage balancing on any branch of the N branches based on the state information of all battery clusters on the branch, the method further comprises:

[0041] Confirming whether the total number of battery clusters successfully powered up is greater than or equal to the minimum number of running battery clusters;

[0042] In response to the total number of battery clusters successfully powered on being greater than or equal to the minimum number of running battery clusters, it is confirmed that the power-on of the energy storage system is completed.

[0043] In this way, when the energy storage system is running, the total number of battery clusters successfully powered on is greater than or equal to the minimum number of running battery clusters, so as to meet the design requirements and use requirements.

[0044] In some embodiments of the present application, before the power-on request is obtained, the state information of all battery clusters in the N branches is obtained, and the state information further includes fault information.

[0045] Based on the fault information of all battery clusters, the fault levels of the battery clusters are determined.

[0046] It is confirmed whether the total number of battery clusters with fault levels lower than the second set level is greater than or equal to the minimum number of running battery clusters.

[0047] In response to the total number of battery clusters with fault levels lower than the second set level being greater than or equal to the minimum number of running battery clusters, the power-on request is obtained.

[0048] In the present embodiment, the precondition for the energy storage system to respond to the power-on request is that the total number of battery clusters with fault levels lower than the second set level is greater than or equal to the minimum number of running battery clusters, so as to reduce the possibility of powering on the battery clusters in a serious fault state, and to improve the safety of the energy storage system.

[0049] The second aspect of the present application provides an energy storage system, comprising: N branches, at least one energy storage converter, and a control unit; each branch is provided with a plurality of battery clusters, the battery cluster includes at least one battery pack, N is a positive integer greater than or equal to 2; each energy storage converter is electrically connected with one branch or K branches connected in parallel, and the battery clusters of each branch can be charged or discharged through the corresponding energy storage converter, K is a positive integer greater than or equal to 2 and less than or equal to N; the control unit is electrically connected with at least one energy storage converter, and the control unit is configured to implement the control method of any one of the energy storage systems provided in the first aspect of the present application.

[0050] The third aspect of the present application provides a computer device, which comprises at least one memory and at least one processor in communication connection with the at least one memory; the at least one memory stores instructions; the at least one processor executes the instructions alone or jointly to implement the control method of any one of the energy storage systems provided in the first aspect of the present application.

[0051] The fourth aspect of the present application provides a computer readable storage medium, which stores instructions, and the instructions are executed by one or more processors of a computer device alone or jointly to implement the control method of any one of the energy storage systems provided in the first aspect of the present application.

[0052] A fifth aspect of the present application provides a computer program product comprising instructions which, when executed by one or more processors of a computer device, alone or in co-operation with one another, implement the control method of any of the energy storage systems according to the first aspect of the present application.

[0053] The above description is only a summary of the technical solutions of the present application. In order to enable one of ordinary skill in the art to better understand the technical means of the present application and implement it according to the contents of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0054] Fig. 1 schematically shows a block diagram of an energy storage system according to an embodiment of the present application;

[0055] Fig. 2 schematically shows a block diagram of an energy storage system according to an embodiment of the present application;

[0056] Fig. 3 schematically shows a block diagram of an energy storage system according to an embodiment of the present application;

[0057] Fig. 4 schematically shows a block diagram of an energy storage system according to another embodiment of the present application;

[0058] Fig. 5 schematically shows a flowchart of a control method of an energy storage system according to an embodiment of the present application;

[0059] Fig. 6 schematically shows a flowchart of a main control unit responding to a power-on instruction of an energy storage system according to an embodiment of the present application;

[0060] Fig. 7 schematically shows a flowchart of a control method of an energy storage system according to another embodiment of the present application. DETAILED DESCRIPTION

[0061] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application; the terms "comprise" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0063] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0064] Reference herein to "embodiments" means that a particular feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0065] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after it.

[0066] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0067] The energy storage system can include an energy storage converter and a plurality of battery clusters. Each battery cluster can include a master control unit and at least one battery pack, each battery pack including at least one battery cell electrically connected. When a battery pack includes multiple (two or more) battery cells, the multiple battery cells can be electrically connected in parallel and / or in series.

[0068] In some related technologies, one energy storage converter of the energy storage system corresponds to all battery clusters.

[0069] It can be understood that when the voltages of the respective battery clusters are different, a larger voltage difference is formed between two battery clusters, and the ring current impact on the battery clusters is easy to cause damage to the battery clusters. In order to reduce the possibility of damage to the battery clusters due to the impact of the ring current, in the control method of the existing energy storage system, the voltage of one of the battery clusters is often taken as a reference voltage, and the voltage difference between the reference voltage and the voltage of the remaining battery clusters is smaller. The battery cluster is controlled to be powered on.

[0070] However, a single energy storage converter corresponds to an energy storage system with all the battery clusters, and the current is large when all the battery clusters are powered on. Therefore, the protection devices (for example, fuses for short-circuit protection and circuit breakers for power-off protection) in the energy storage system need to be selected from high-current rated types, resulting in high requirements for protection devices and great difficulty in selection.

[0071] To solve the above problems, the related art also proposes an energy storage system composed of multiple branches, and each branch is provided with multiple battery clusters in parallel. Compared with all the battery clusters in parallel, by setting multiple branches, the number of battery clusters in each branch is relatively reduced, so as to reduce the requirements for protection devices and thus reduce the difficulty in selection of protection devices. When the existing control method is applied to the energy storage system composed of multiple branches, for the branches with large differences between the voltage of each battery cluster and the reference voltage, the branches are not powered on, resulting in low external discharge power of the energy storage system. Therefore, for the energy storage system composed of multiple branches, it is urgent to improve the control method of the energy storage system.

[0072] In the present application, an energy storage system and a control method thereof are designed. When a power-on request is obtained, each branch can be independently controlled to perform a power-on process, so that the power-on logic of each branch does not affect each other. For any branch, a certain battery cluster or multiple battery clusters for voltage balancing on the branch are powered on. In this way, all branches can be powered on under the premise that the possibility of circulating current in each branch is low, which can improve the external discharge power of the energy storage system.

[0073] The energy storage system disclosed in the embodiments of the present application can be applied in a power system, and the energy storage system disclosed in the present application can be used as an energy supplement of the power system.

[0074] The energy storage system disclosed in the embodiments of the present application can also be applied in an electric device, and the energy storage system disclosed in the present application can be used to form a power system of the electric device. The electric device can be, but is not limited to, a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. The electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric plane toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0075] The following embodiments take the power system of an embodiment of the present application as an example for convenience of description.

[0076] Please combine the figures shown in FIG. 1 and FIG. 2, the energy storage system can include N branches, at least one power conversion system (PCS) and a control unit, N is a positive integer greater than or equal to 2. The number of branches is not limited to two as shown in FIG. 1, and can be customized according to actual working conditions.

[0077] Each branch is provided with Q battery clusters connected in parallel and independent of each other, Q is also a positive integer greater than or equal to 2. The number of battery clusters in each branch can be the same or different. Each battery cluster can be installed in an independent electrical cabinet to protect the battery cluster from the external environment. The battery cluster can include at least one battery pack, that is, the battery cluster can include one or a plurality of battery packs connected in series. The battery cluster can also include a master control unit (BCMU) for controlling the operating state of at least one battery pack in the battery cluster. Each battery pack can include a plurality of battery cells electrically connected in parallel and / or series, and each battery pack can also include a battery management unit (BMU) for controlling the operating state of the plurality of battery cells in the battery pack.

[0078] The energy storage system can also include N busbars corresponding to the N branches, and the positive and negative electrodes of each battery cluster in the same branch are connected to the positive and negative terminals of the corresponding power conversion system through the same busbar. Please combine FIG. 3 and FIG. 4, a main positive relay K+ can be provided between the positive electrode of each battery cluster and the corresponding power conversion system, and a main negative relay K- can be provided between the negative electrode of each battery cluster and the power conversion system, and the battery cluster, the main positive relay K+, the main negative relay K- and the power conversion system form a main circuit in series. The main positive relay K+ can also be connected in parallel with a pre-charge circuit, which includes a pre-charge relay S and a pre-charge resistor R connected in series.

[0079] Each power conversion system is electrically connected with K branches, so that the battery clusters of each branch can be charged or discharged through the corresponding power conversion system, K is a positive integer, and K≤N. When K is greater than or equal to 2 and less than or equal to N, the K branches corresponding to the same power conversion system are connected in parallel. It can be understood that the power conversion system can be one, and one power conversion system is electrically connected with N branches.

[0080] The power conversion system can also be multiple, and the number of branches corresponding to each power conversion system can be the same or different. In one way of the present embodiment, the number of power conversion systems can be consistent with the number of branches, that is, the number of power conversion systems is also N, and the N power conversion systems correspond to the N branches one by one. In the embodiment where N≥3 and the number of power conversion systems is not less than two, part of the power conversion systems can be connected corresponding to one branch, and the remaining part of the power conversion systems can be connected corresponding to multiple branches of the N branches.

[0081] The energy storage converter is electrically connected with the power consuming device and the power generating device. The energy storage converter can charge or discharge the battery cluster. Specifically, the power generating device charges the battery cluster of the corresponding branch through the energy storage converter, and the multiple battery clusters on the branch supply power to the power consuming device through the corresponding energy storage converter. The energy storage converter can also convert AC and DC, can directly supply power to the AC load in the case of no power grid, and can realize the adjustment of active power and reactive power of the power grid.

[0082] The control unit is used to control the running state of at least one energy storage converter included in the energy storage system and all battery clusters on each branch.

[0083] The control unit can be configured to have communication capability. The control unit can communicate with at least one energy storage converter and the master control unit (BCMU) of each battery cluster through a CAN (Controller Area Network) bus or Ethernet, but is not limited thereto. Specifically, taking the CAN bus communication as an example, the control unit has a multi-channel RS485 and CAN bus interface. The control unit is connected with the master control unit (BCMU) of each battery cluster through the CAN bus. The control unit and the master control unit serve as nodes on the CAN bus, can send messages (i.e. data frames, overload frames and error frames, etc.) to the CAN bus, and can receive the entire message when the required message is listened to and identified, so that the control unit and each master control unit can communicate. The master control unit (BCMU) can also be connected with each battery management unit (BMU) in the corresponding battery cluster through the CAN bus, so that the master control unit and each battery management unit can communicate with each other as nodes on the CAN bus.

[0084] The control unit can also be configured to have a parameter configuration function, which can not only modify its own parameters, but also modify the control parameters in the form of issuing commands through the CAN bus. The control unit can also realize the communication function with the background monitoring system, upload system information in real time and accept the monitoring instructions of the monitoring background.

[0085] The control unit, the master control unit and the battery management unit can jointly constitute at least part of a battery management system (BMS), and the battery management system is used to monitor the battery state and can also be used to connect with external devices.

[0086] In some embodiments, the energy storage system can also include an energy management system (EMS), and the control unit can communicate with the energy management system through a CAN bus or a device network bus, but is not limited thereto. The energy management system is used for energy scheduling.

[0087] The embodiment of the present application provides a control method of an energy storage system. The control method can be executed by a control unit of the energy storage system, that is, the execution subject of the control method is the control unit, and the control unit is used for managing and controlling the running state of at least one energy storage converter and all battery clusters on each branch included in the energy storage system.

[0088] Fig. 5 schematically shows a flow chart of the control method of the energy storage system according to an embodiment of the present application. As shown in Fig. 5, the control method mainly comprises the following steps.

[0089] S110, obtaining a power-on request.

[0090] The power-on request can be sent by the energy storage converter or an external device. In the embodiment in which the energy storage system further comprises an energy management system, the power-on request can be sent by the energy storage converter or the external device, or can be sent by the energy management system.

[0091] S120, in response to the power-on request, obtaining state information of all battery clusters on each branch, and the state information at least comprises an internal sampling voltage Va.

[0092] As shown in Figs. 3 and 4, the internal sampling voltage Va refers to the potential difference between the positive electrode and the negative electrode of the main circuit corresponding to the battery cluster in the open circuit state (the main positive relay and the main negative relay are not closed), and can also be understood as the potential difference between the first end (that is, the a end connected with the positive electrode of the battery cluster) of the main positive relay and the first end (that is, the b end connected with the negative electrode of the battery cluster) of the main negative relay. When the battery cluster comprises a plurality of battery packs connected in series, the internal sampling voltage Va can be understood as the sum of the voltage values of the plurality of battery packs included in the battery cluster in the open circuit state. Since the internal sampling voltage Va refers to the potential difference between the first end of the main positive relay and the first end of the main negative relay in the open circuit state of the main circuit corresponding to the battery cluster, the corresponding internal sampling voltage Va can be collected when the battery cluster is not powered on.

[0093] In combination with the above content, the battery management unit can report the state information of the corresponding battery pack to the master control unit, the master control unit can comprehensively arrange the received state information of the battery pack into the state information of the battery cluster and report the state information to the control unit, and the control unit can receive the state information of the battery cluster sent by each master control unit.

[0094] S130, for any branch of the N branches, based on the state information of all battery clusters on the branch, send a power-on instruction to one of the battery clusters on the branch or to the M battery clusters on the branch that satisfy voltage balance, M is a positive integer greater than or equal to 2, and voltage balance means that the difference between the internal sampling voltage of the remaining battery clusters and the reference voltage, which is the voltage value related to one of the M battery clusters, is less than the first threshold value, and the power-on instruction is used to instruct the corresponding battery cluster to perform the power-on operation.

[0095] The control unit can obtain the internal sampling voltage of all battery clusters on any branch based on the state information of the battery clusters reported by each master control unit. In response to the internal sampling of any two battery clusters on the branch not satisfying voltage balance, a power-on instruction is sent to one of the battery clusters on the branch. In response to the internal sampling of M battery clusters among the Q battery clusters on the branch satisfying voltage balance, a power-on instruction is sent to the M battery clusters, 2≤M≤Q. The first threshold value is a voltage difference threshold value representing the generation of circulating current between any two of the plurality of battery clusters. The first threshold value can be in the range of 10V to 20V, and the first threshold value can be any of 10V, 15V and 20V.

[0096] The power-on instruction sent to the battery cluster can be sent to the master control unit of the battery cluster, and the master control unit receives the power-on instruction to control the corresponding battery cluster to perform the power-on operation. The power-on operation can mean connecting the battery cluster to the corresponding busbar to communicate with the high-voltage circuit through the corresponding energy storage converter.

[0097] Therefore, when the control method of the energy storage system of the present application is applied to an energy storage system with multiple branches, the control unit can control each branch to independently power on in response to the power-on request, so that each branch does not need to logically compare and judge the voltage of the battery cluster of the branch with the voltage of the battery cluster on another branch when implementing power-on control, i.e. the power-on logic of each branch does not interfere with each other. And for any branch, when there are M battery clusters in voltage balance, M battery cluster power-on control is implemented, and when any two battery clusters are not in voltage balance, one battery cluster power-on control is implemented. In this way, at least one battery cluster on each branch is powered on, so that N branches can be powered on. Compared with the related art in which some branches cannot be powered on, this can improve the external discharge capacity of the energy storage system. At the same time, it can minimize the possibility of circulating current on the branch damaging the battery cluster on the branch.

[0098] In S130, for any branch, it can be confirmed whether the internal sampling of the M battery clusters satisfies voltage balance before all the battery clusters on the branch perform power-on operation; or a first battery cluster can be determined among the Q battery clusters, the first battery cluster performs power-on operation first, and a voltage value related to the first battery cluster is taken as a reference voltage, and then it is confirmed whether the battery cluster is in voltage balance with the first battery cluster among the remaining battery clusters on the branch. The following describes two possible implementation manners.

[0099] In some implementation manners of the present application, S130 can be implemented by the following steps.

[0100] Step 1, for any branch of the N branches, the state information of all the battery clusters on the branch is obtained, and the highest internal sampling voltage and the lowest internal sampling voltage are determined.

[0101] The highest internal sampling voltage can be the highest value of the internal sampling voltage of all the battery clusters, and the lowest internal sampling voltage can be the lowest value of the internal sampling voltage of all the battery clusters.

[0102] Step 2, taking one of the highest internal sampling voltage and the lowest internal sampling voltage as a reference voltage, it is confirmed whether the difference between the other of the highest internal sampling voltage and the lowest internal sampling voltage and the reference voltage is less than a first threshold value.

[0103] Step 3, if yes, it is confirmed that the internal sampling voltages of all the battery clusters on the branch are balanced, and power-on instructions are sent to all the battery clusters on the branch.

[0104] In steps 2 and 3, by comparing the highest internal sampling voltage and the lowest internal sampling voltage, when the difference between the highest internal sampling voltage and the lowest internal sampling voltage is less than the first threshold value, the difference between the internal sampling voltages of any two battery clusters is less than the first threshold value. On this basis, power-on instructions are sent to all the battery clusters, so that no loop current is generated between any two battery clusters on the branch which are successfully powered on, which can reduce the possibility of loop current damaging the battery clusters.

[0105] Among them, the power-on instructions can be sent to all the battery clusters on the branch at the same time, or the power-on instructions can be sent to all the battery clusters on the branch in a sequence.

[0106] Step 4, if no, a power-on instruction is sent to one of the battery clusters on the branch.

[0107] In some implementation manners of the present application, S130 can be implemented by the following steps.

[0108] S131, for any branch of the N branches, based on the state information of all the battery clusters on the branch, a first battery cluster is determined among all the battery clusters.

[0109] S132, sending a power-on instruction to the first battery cluster.

[0110] This step can be understood as sending a power-on instruction to the master control unit of the first battery cluster. The master control unit of the first battery cluster receives the power-on instruction and controls the first battery cluster to perform the power-on operation.

[0111] S133, in the case of successful power-on of the first battery cluster, confirming whether there is a second battery cluster on the branch, the second battery cluster is voltage balanced with the first battery cluster, and the reference voltage is related to the first battery cluster.

[0112] Successful power-on means that the main positive relay K+ and the main negative relay K- of the main circuit where the first battery cluster is located are closed, and the first battery cluster is connected to the corresponding busbar. According to the content described above, the voltage balance between the second battery cluster and the first battery cluster means that the voltage value related to the first battery cluster is taken as the reference voltage, and the difference between the internal sampling voltage of the second battery cluster and the reference voltage is less than the first threshold value.

[0113] S134, in response to the existence of the second battery cluster on the branch, sending a power-on instruction to the second battery cluster.

[0114] When there are multiple second battery clusters, the power-on instruction can be sent to multiple second battery clusters simultaneously in S134, or the power-on instruction can be sent to multiple second battery clusters in turn according to the order of priority (for example, the order of size of the physical addresses of the multiple second battery clusters).

[0115] S135, in response to the absence of the second battery cluster on the branch, ending the power-on process.

[0116] S136, in the case of failure of the first battery cluster to power on, based on the state information of the remaining battery clusters on the branch, determining a new battery cluster to replace the first battery cluster among the remaining battery clusters, and returning to S132.

[0117] As can be seen from the above, when step S132 is executed, only a single battery cluster on the branch performs the power-on operation, at this time, other battery clusters are not powered on, so no circulating current is generated. When step S134 is executed, multiple battery clusters exist on the branch to perform power-on, and since the first battery cluster and the second battery cluster satisfy the voltage balance, it means that when the first battery cluster and the second battery cluster are powered on at the same time, no circulating current will be generated between them.

[0118] Compared with the manner that M battery clusters on the confirmation branch are caused to perform power-on operation after the M battery clusters are caused to perform voltage equalization, in the embodiment, the power-on procedure for any branch can be regarded as being divided into single battery cluster power-on and multi-battery cluster power-on two stages, and the multi-battery cluster power-on stage is established on the basis of the single battery cluster power-on stage and the successful power-on of the first battery cluster. In this way, a single battery cluster (i.e., the first battery cluster) is caused to perform power-on operation on each branch first, so that the single battery cluster power-on stage does not generate circulating current. In the multi-battery cluster power-on stage, since the first battery cluster and the second battery cluster are equalized in voltage, the possibility of circulating current between the first battery cluster and the second battery cluster is low, which is conducive to improving the operation stability of the energy storage system.

[0119] Optionally, S133 can specifically be that, in the case that the first battery cluster is successfully powered on, a reference voltage is acquired, the reference voltage being the internal sampling voltage of the first battery cluster; it is determined whether there is a battery cluster in the remaining battery clusters on the branch whose internal sampling voltage and the reference voltage have a difference less than a first threshold value; and based on the determination result, it is determined whether there is a second battery cluster. In the embodiment, the internal sampling voltage of the first battery cluster is set as the reference voltage, and the internal sampling voltages of the first battery cluster and the second battery cluster are equalized, i.e., the difference between the internal sampling voltage of the second battery cluster and the internal sampling voltage of the first battery cluster is less than the first threshold value.

[0120] In some embodiments of the present application, S133 can be replaced by the following steps.

[0121] S1331, in the case that the first battery cluster is successfully powered on, a reference voltage is acquired, the reference voltage being the external sampling voltage of the first battery cluster.

[0122] In the embodiment, the state information further includes an external sampling voltage Vd, which refers to the potential difference between the second end of the main positive relay K+ of the main circuit in which the battery cluster is located (i.e., the A end connected to the positive end of the energy storage converter) and the second end of the main negative relay K- of the main circuit in which the battery cluster is located (i.e., the B end connected to the negative end of the energy storage converter). That is, the master control unit can acquire not only the internal sampling voltage of the corresponding battery cluster but also the external sampling voltage of the corresponding battery cluster. It should be understood that when the main positive relay K+ and the main negative relay K- of the main circuit in which the battery cluster is located are closed, the external sampling voltage Vd corresponding to the battery cluster can be collected.

[0123] In this step, after the first battery cluster is successfully powered on, the master control unit of the first battery cluster acquires the external sampling voltage and reports it to the control unit, and the control unit receives the external sampling voltage and uses it as the reference voltage.

[0124] S1332, it is determined whether there is a battery cluster in the remaining battery clusters on the branch whose internal sampling voltage and the reference voltage have an absolute value of the difference less than a first threshold value.

[0125] S1333, confirming whether the second battery cluster exists based on the judgment result.

[0126] The meanings of S1332 and S1333 are that the battery cluster satisfying “|internal sampling voltage-reference voltage|<first threshold value” on the branch is screened out as the second battery cluster, that is, the second battery cluster needs to satisfy “|internal sampling voltage of the second battery cluster-external sampling voltage of the first battery cluster|<first threshold value”.

[0127] Compared with the reference voltage being the internal sampling voltage of the first battery cluster and the internal sampling voltage of the second battery cluster being equal to the internal sampling voltage of the first battery cluster, the embodiment takes the external sampling voltage of the first battery cluster successfully powered on as the reference voltage, which means that the voltage of the circuit is normal when the first battery cluster accesses the energy storage converter. By designing that the second battery cluster needs to satisfy that the absolute value of the difference between its internal sampling voltage and the reference voltage is less than the first threshold value, the internal sampling voltage of the screened second battery cluster is equal to the external sampling voltage of the first battery cluster successfully powered on, which makes the possibility of circulating current between the second battery cluster accessing the bus and the first battery cluster low, and also makes the voltage of the circuit normal when the second battery cluster accesses the energy storage converter, thereby being conducive to reducing the risk of high pressure impact on the energy storage converter caused by the excessive pressure difference between the second battery cluster and the energy storage converter.

[0128] In some examples, the first battery cluster can be the battery cluster corresponding to the highest internal sampling voltage, or the battery cluster corresponding to the lowest internal sampling voltage.

[0129] In some examples, each branch is provided with at least three battery clusters, that is, Q≥3, and the first battery cluster can also be the battery cluster corresponding to the internal sampling voltage in the middle position.

[0130] In the embodiment, the first battery cluster is determined in all battery clusters in S131, which can be specifically: the battery cluster with the internal sampling voltage in the middle position is determined as the first battery cluster in all battery clusters.

[0131] Compared with the battery cluster corresponding to the highest internal sampling voltage and the battery cluster corresponding to the lowest internal sampling voltage, in this embodiment, the internal sampling voltage of the first battery cluster is arranged in the middle position, so that the battery cluster on the branch satisfying the condition of "internal sampling voltage-reference voltage<first threshold value" can be determined as the second battery cluster, and the battery cluster on the branch satisfying the condition of "reference voltage-internal sampling voltage<first threshold value" can also be determined as the second battery cluster. That is, under the premise of balancing the internal sampling voltage of the second battery cluster and the internal sampling voltage of the first battery cluster, the number of the second battery cluster can be increased, M is as large as possible, so that as many battery clusters on each branch as possible perform the power-up operation, so that the N branches can all realize power-up at the same time, which is beneficial to increasing the number of battery clusters connected to the energy storage converter on the branch, and is beneficial to improving the external discharge power of the energy storage system.

[0132] In some embodiments of the present application, further, the state information can also include fault information. In this example, S130 is specifically for any branch of the N branches, based on the state information of all battery clusters on the branch, sending a power-up instruction to one of the battery clusters on the branch satisfying the allowed power-up condition or to the M battery clusters on the branch satisfying the allowed power-up condition and voltage balancing; wherein the allowed power-up condition includes a fault level lower than a first set level.

[0133] That is, the battery cluster performing the power-up operation needs to satisfy the allowed power-up condition, that is, the fault level of the battery cluster performing the power-up operation should be lower than the first set level.

[0134] Based on this, in the embodiment of the specific implementation process of S130 as steps S131 to S136, both the first battery cluster and the second battery cluster need to satisfy the allowed power-up condition.

[0135] In this embodiment, by designing to send a power-up instruction to the battery cluster on the branch satisfying the allowed power-up condition, it is ensured that the battery cluster receiving the power-up instruction to perform the power-up operation should satisfy the allowed power-up condition, which is beneficial to enabling the battery cluster receiving the power-up instruction to be normally powered up, so that it is not necessary to send a power-up instruction to the battery cluster not satisfying the allowed power-up condition, which is beneficial to simplifying the control process of the energy storage system, and at the same time, is beneficial to reducing the adverse effects of faults on the energy storage system.

[0136] In the embodiment of the specific implementation process of S130 as steps S131 to S136, in S131, the battery cluster satisfying the allowed power-up condition can be first screened out, and then the battery cluster in the middle position of the sorting can be determined as the first battery cluster, or the battery cluster in the middle position of the sorting can be first determined, and then it is judged whether the battery cluster satisfies the allowed power-up condition. The two possible implementation manners are described below.

[0137] In some examples, the implementation process of S131 can be: for any one branch, based on the state information reported by the master unit of all battery clusters, a battery cluster that meets the allowed power-on condition is screened out from all battery clusters (i.e., Q battery clusters) as a power-on group; then the internal sampling voltage of the battery cluster that meets the allowed power-on condition in the power-on group is sorted, and the battery cluster that is sorted in the middle position is determined as the first battery cluster, and the voltage value related to the first battery cluster is taken as the reference voltage. Correspondingly, S1332 can be: screening out a battery cluster that meets the condition of “|internal sampling voltage-reference voltage|<first threshold” from the other battery clusters in the power-on group except the first battery cluster as the second battery cluster, and the second battery cluster also meets the allowed power-on condition.

[0138] In other examples, the implementation process of S131 can also be the following steps.

[0139] S1311, for any one branch, the internal sampling voltages of all battery clusters are sorted first, and the battery cluster that is sorted in the middle position is determined.

[0140] S1312, based on the state information reported by the master unit of the battery cluster, it is confirmed whether the battery cluster that is sorted in the middle position meets the allowed power-on condition.

[0141] S1313, in response to the battery cluster that is sorted in the middle position meeting the allowed power-on condition, the battery cluster is determined as the first battery cluster.

[0142] S1314, in response to the battery cluster that is sorted in the middle position not meeting the allowed power-on condition, the battery cluster that is sorted in the middle position is determined from the remaining battery clusters, and S1312 is returned.

[0143] In this example, S1333 can be implemented by the following steps: in the case of yes, based on the state information reported by the master unit of the battery cluster, it is confirmed whether the battery cluster that meets the condition of “|internal sampling voltage-reference voltage|<first threshold” meets the allowed power-on condition; when the allowed power-on condition is met, the battery cluster is confirmed as the second battery cluster.

[0144] The above sorting method can be in the order from small to large, or in the order from large to small. Here, taking the example of sorting first and then judging whether the allowed power-on condition is met, the internal sampling voltages of the Q battery clusters on the branch are sorted in S1311. If Q is odd, the (Q+1) / 2th internal sampling voltage is sorted in the middle position; if Q is even, the Q / 2th internal sampling voltage is sorted in the middle position or the (Q / 2)+1th internal sampling voltage is sorted in the middle position.

[0145] The way of confirming whether the battery cluster meets the allowed power-on condition based on the state information is also various.

[0146] Optionally, the state information reported by the battery management unit to the master control unit includes fault information, the master control unit can comprehensively arrange the received state information of the battery pack into state information of the battery cluster and report it to the control unit, the state information of the battery cluster received by the control unit includes fault information, the control unit can confirm the fault level of the battery cluster according to the fault information, and in response to the fault level of the battery cluster being lower than a first set level, it is confirmed that the battery cluster meets the power-on enabling condition. Here, it should be pointed out that the fault level of the battery cluster is level 1 to level 7, and the higher the fault level, the more serious the fault. The first set level is a fault level threshold value representing that the battery cluster cannot be powered on, which can be selected according to experience and actual working conditions, for example, it can be level 4.

[0147] In an alternative manner, the state information reported by the battery management unit to the master control unit includes fault information, the master control unit can confirm the fault level of the battery cluster based on the state information of the battery pack, and in response to the fault level of the battery cluster being lower than a first set level (for example, level 4), the power-on flag bit is switched from low to high, and the state information including the power-on enabling signal is reported to the control unit, and the control unit receives the state information including the power-on enabling signal, and confirms that the battery cluster meets the power-on enabling condition based on the power-on enabling signal.

[0148] In this embodiment, the master control unit does not need to analyze the fault information of the battery cluster to confirm the fault level of the battery cluster, but can determine that the battery cluster meets the power-on trigger condition when it is confirmed that the power-on enabling signal is received. As can be seen, the way of confirming whether the battery cluster meets the power-on trigger condition is fast and simple, which is conducive to improving the operation efficiency of the energy storage system.

[0149] In some embodiments of the present application, in S130, the power-on instruction is sent to any one of the battery clusters, and the power-on duration of the battery cluster is also timed; in response to the battery cluster completing the power-on operation within a first preset time duration, it is confirmed that the battery cluster is powered on successfully; and in response to not completing the power-on operation within the first preset time duration, it is confirmed that the battery cluster fails to power on.

[0150] As can be known from the foregoing, in the embodiment in which S130 includes S131 to S136, S132 can be to time the power-on duration of the first battery cluster while sending the power-on instruction to the first battery cluster; and in response to the first battery cluster completing the power-on operation within a first preset time duration, it is confirmed that the first battery cluster is powered on successfully.

[0151] The power-on duration refers to the time required for the battery cluster to access the busbar so that the battery cluster can operate normally. For a battery cluster with normal functions, the power-on duration is generally short. When the power-on duration of a certain battery cluster is too long, it indicates that the battery cluster is not in a normal working state. If the battery cluster is kept in the power-on state, it may lead to further failure or even accidents of the battery cluster. The first preset duration is a threshold value preset for the power-on duration.

[0152] In this embodiment, the first preset duration is set as the threshold value to determine whether the power-on duration of the battery cluster is too long. The power-on duration of the battery cluster that has successfully powered on does not exceed the first preset duration, and thus the functions of the battery cluster that has successfully powered on are normal. In this way, the possibility of powering on the battery cluster that is not in a normal function state and leading to failure or even accidents can be reduced.

[0153] In some embodiments of the present application, the state information can include not only the internal sampling voltage but also the external sampling voltage. The power-on instruction can be configured to instruct the pre-charging circuit of the corresponding battery cluster to power on, to acquire the pre-charging duration, the internal sampling voltage and the external sampling voltage of the battery cluster, to instruct the corresponding battery cluster to determine whether the absolute value of the potential difference between the internal sampling voltage and the external sampling voltage of the battery cluster within the second preset duration is less than the second threshold value based on the pre-charging duration, the internal sampling voltage and the external sampling voltage, and to instruct the corresponding battery cluster to power on the main circuit of the battery cluster and disconnect the pre-charging circuit in response to the absolute value of the potential difference between the internal sampling voltage and the external sampling voltage of the battery cluster within the second preset duration being less than the second threshold value.

[0154] Optionally, the power-on instruction can be configured to instruct the corresponding battery cluster to fail to power on in response to the absolute value of the potential difference between the internal sampling voltage and the external sampling voltage of the battery cluster within the second preset duration being greater than or equal to the second threshold value.

[0155] That is, in combination with FIG. 6, the control method of the battery cluster after the control unit receives the power-on instruction includes the following S410 to S460.

[0156] S410, the pre-charging circuit of the battery cluster is powered on.

[0157] S420, the pre-charging duration, the internal sampling voltage and the external sampling voltage of the battery cluster are acquired.

[0158] S430, it is determined whether the absolute value of the potential difference between the internal sampling voltage and the external sampling voltage of the battery cluster within the second preset duration is less than the second threshold value. If yes, S440; if no, S460.

[0159] S440, the main circuit of the battery cluster is powered on, and the pre-charging circuit is disconnected.

[0160] S450, confirming that the battery cluster is powered on successfully.

[0161] S460, confirming that the battery cluster fails to be powered on.

[0162] According to the foregoing, the control unit sends a power-on instruction to the master control unit of the battery cluster, and the master control unit responds to the power-on instruction. Specifically, the master control unit, in response to the power-on instruction, causes the pre-charging circuit of the corresponding battery cluster to be powered on, which can be achieved by first controlling the main negative relay to be closed and then controlling the pre-charging relay to be closed, so that the pre-charging circuit is turned on.

[0163] The pre-charging duration refers to the time for which the pre-charging circuit is powered on. For a battery cluster that functions normally, the condition “|internal sampling voltage of the battery cluster - external sampling voltage of the battery cluster| < second threshold value” can be met within a short pre-charging duration. When the pre-charging duration is too long, the condition “|internal sampling voltage of the battery cluster - external sampling voltage of the battery cluster| < second threshold value” is met, which indicates that the battery cluster is not in a normal working state. If the battery cluster continues to be powered on, it may further malfunction or even cause an accident. The second preset duration is a threshold value preset for the pre-charging duration.

[0164] The present embodiment is designed in this way. When the battery cluster is powered on, the pre-charging circuit is powered on before the main circuit to perform pre-charging, which helps to reduce the risk of high-voltage impact on the energy storage converter caused by excessive voltage difference between the battery cluster and the energy storage converter.

[0165] In addition, the present embodiment also sets the second preset duration as a threshold value to determine whether the pre-charging duration of the battery cluster is too long, so that the battery cluster with a pre-charging duration within the second preset duration continues to be powered on. This can reduce the possibility of malfunction or even accidents caused by powering on a battery cluster that is not in a normal functional state. The second preset duration can be reasonably designed according to experience and actual working conditions, for example, it can be 100 ms or 200 ms.

[0166] In some embodiments, the master control unit, in response to the power-on instruction, causes the main circuit of the battery cluster to be powered on and the pre-charging circuit to be disconnected. Specifically, it can be achieved by first controlling the main positive relay to be closed, so that the main circuit is powered on, and then controlling the pre-charging relay to be disconnected after a third preset duration, so as to disconnect the pre-charging circuit. The third preset duration can be designed according to experience and requirements, for example, it can be 1000 ms.

[0167] By designing the main circuit to be powered on and then disconnecting the pre-charging circuit after a third preset duration, the pre-charging circuit remains in a closed state during the process of connecting the main circuit to the busbar to connect to the high-voltage circuit. This helps to further reduce the possibility of high-voltage impact on the energy storage converter caused by excessive voltage difference between the internal sampling voltage of the battery cluster and the energy storage converter.

[0168] In some embodiments, the power-on of the energy storage system is confirmed to be completed in response to at least one battery cluster on any of the N branches being successfully powered on. This is conducive to all branches being successfully powered on when the energy storage system is in operation, thereby improving the external discharge capacity and operation stability of the energy storage system.

[0169] In some embodiments of the present application, after S130, the control method of the energy storage system can further include the following steps.

[0170] S140, confirming whether the total number of battery clusters successfully powered on exceeds the minimum number of running battery clusters.

[0171] The minimum number of running battery clusters is pre-set, and the minimum number of running battery clusters ≤ Q, which can be 1, 2, 3, 4, or 5, for example.

[0172] S150, confirming the power-on of the energy storage system to be completed in response to the total number of battery clusters successfully powered on exceeding the minimum number of running battery clusters.

[0173] In the present embodiment, the power-on of the energy storage system is confirmed to be completed when the total number of battery clusters successfully powered on exceeds the minimum number of running battery clusters, which is conducive to the total number of battery clusters successfully powered on being greater than or equal to the minimum number of running battery clusters when the energy storage system is in operation, so as to meet the design requirements and use requirements.

[0174] In some embodiments of the present application, the control method of the energy storage system can further include:

[0175] Before S110, the state information of all battery clusters on the N branches is obtained, and the state information can further include fault information; the fault level of each battery cluster is determined based on the fault information of all battery clusters; it is confirmed whether the total number of battery clusters with a fault level lower than the second set level is greater than or equal to the minimum number of running battery clusters; and S110 is executed in response to the total number of battery clusters with a fault level lower than the second set level being greater than or equal to the minimum number of running battery clusters.

[0176] As known from the foregoing, the fault level of a battery cluster is from level 1 to level 7, and the higher the fault level, the more serious the fault. The second set level is a threshold value for representing whether a battery cluster has a fault that affects its normal power-on, which can be level 6 fault or level 7 fault, for example. The second set level is greater than the first set level.

[0177] With the design, by judging the failure levels of the battery clusters, the precondition for the energy storage system to respond to the power-on request is that the total number of the battery clusters with the failure level lower than the second set level is greater than or equal to the minimum number of the running battery clusters, that is, the number of the battery clusters capable of normal power-on is not less than the minimum number of the running battery clusters, so as to reduce the possibility of power-on of the battery clusters in a serious failure state and reduce the adverse effects of the failure on the energy storage system, thereby improving the safety of the energy storage system.

[0178] As shown in FIG. 1 and FIG. 2, the embodiment of the present application also provides an energy storage system, which comprises N branches, at least one energy storage converter and a control unit; each branch is provided with a plurality of battery clusters connected in parallel and independent of each other, the battery cluster comprises at least one battery pack, and N is a positive integer greater than or equal to 2; each energy storage converter is electrically connected with one branch or K branches connected in parallel, and the battery clusters of each branch can be charged or discharged through the corresponding energy storage converter, K is a positive integer greater than or equal to 2 and less than or equal to N; the control unit is electrically connected with the at least one energy storage converter, and the control unit is configured to implement the control method of the energy storage system of any one of the above embodiments.

[0179] The embodiment of the present application also provides a computer device, which comprises at least one memory and at least one processor in communication connection with the at least one memory; the at least one memory stores instructions; and the at least one processor executes the instructions alone or in combination to implement the control method of the energy storage system of any one of the above embodiments.

[0180] The various embodiments of the systems and techniques described above in the present application can be implemented in digital electronic circuitry, integrated circuitry, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), an application specific standard product (ASSP), a system on a chip (SOC), a programmable logic device (CPLD), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0181] The embodiment of the present application also provides a computer readable storage medium, which stores instructions, and the instructions are executed by one or more processors of a computer device alone or in combination to implement the control method of the energy storage system of any one of the above embodiments.

[0182] The computer readable medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium will include one or more lines of electrical connections, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fibers, portable compact disc read-only memories (CD-ROMs), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0183] The embodiments of the present application also provide a computer program product comprising instructions which, when executed by one or more processors of a computer device, alone or in combination, implement the control method of the energy storage system according to any one of the above embodiments.

[0184] The above description is only a summary of the technical solutions of the present application. In order to enable one skilled in the art to better understand the technical means of the present application and to implement the same according to the contents of the description, and in order to enable the above and other purposes, features and advantages of the present application to be more apparent and easy to understand, the specific embodiments of the present application are described below.

[0185] In the embodiments of the present application, as shown in FIGS. 1 and 2, the energy storage system comprises N branches, at least one energy storage converter and a control unit, N is a positive integer greater than or equal to 2. Each branch is provided with Q battery clusters connected in parallel and independent of each other, Q is a positive integer greater than or equal to 3, the battery cluster comprises at least one battery pack and a master control unit for controlling the operating state of the at least one battery pack in the battery cluster, and each battery pack comprises a plurality of battery monomers and a battery management unit for controlling the operating state of the plurality of battery monomers in the battery pack. The energy storage converter is electrically connected with the power consuming device and the power generating device.

[0186] The control unit is also in communication connection with the master control unit and the energy storage converter through the CAN bus. The master control unit is in communication connection with the battery management unit through the CAN bus. The battery management unit reports the state information of the corresponding battery pack to the master control unit, which can include but is not limited to at least one of the following: internal sampling voltage, external sampling voltage, fault information, power-on permission signal, temperature, health status, etc. The master control unit then reports the state information of the battery pack reported by the battery management unit to the control unit after comprehensive arrangement.

[0187] As shown in FIG. 7, the control method of the energy storage system comprises the following steps. The execution subject of the control method of the energy storage system is the control unit.

[0188] S210, acquire state information of all battery clusters on the N branches.

[0189] S220, determine the fault level of each battery cluster based on the fault information of all battery clusters.

[0190] S230, confirm whether the total number of battery clusters with fault levels lower than 6 is greater than or equal to the minimum number of operating battery clusters.

[0191] S240, in response to the total number of battery clusters with fault levels lower than 6 being greater than or equal to the minimum number of operating battery clusters, acquire a power-on request.

[0192] S250, in response to the power-on request, acquire state information of all battery clusters on each branch.

[0193] S260, for any branch of the N branches, based on the state information of all battery clusters on the branch, send a power-on instruction to one of the battery clusters on the branch or to M battery clusters on the branch that satisfy voltage balance, M being a positive integer greater than or equal to 2, voltage balance referring to the difference between the internal sampling voltage of the remaining battery clusters and the reference voltage being less than a first threshold value, the reference voltage being the voltage value related to one of the M battery clusters, the power-on instruction being used to instruct the corresponding battery cluster to perform a power-on operation.

[0194] S270, confirm whether the total number of battery clusters that have successfully powered on is greater than or equal to the minimum number of operating battery clusters.

[0195] S280, in response to the total number of battery clusters that have successfully powered on being greater than or equal to the minimum number of operating battery clusters, confirm that the power storage system has powered on and issue a request power instruction.

[0196] S290, in response to the total number of battery clusters that have successfully powered on being less than the minimum number of operating battery clusters, issue a power-on failure instruction.

[0197] In step S260, the power-on process for any branch of the N branches includes steps S31 to S44.

[0198] S31, based on the state information of all battery clusters on the branch, screen out the battery clusters that satisfy the allowed power-on condition (the fault level of the battery cluster being lower than level 4) from all the battery clusters as the power-on-allowed group.

[0199] S32, sort the internal sampling voltages of each battery cluster in the up-chargeable group in ascending order, and determine the battery cluster with the internal sampling voltage in the middle position in the up-chargeable group as the first battery cluster. In this step, when the up-chargeable group has an odd number of battery clusters, the battery cluster with the internal sampling voltage in the (number of battery clusters / 2)th position is taken as the first battery cluster. When the up-chargeable group has an even number of battery clusters, the battery cluster with the internal sampling voltage in the (number of battery clusters / 2)+1th position is taken as the first battery cluster.

[0200] S33, send the up-charge instruction to the first battery cluster, and also count the up-charge duration of the first battery cluster.

[0201] S34, confirm whether the first battery cluster completes the up-charge operation within the first preset duration; if yes, go to S35; if no, go to S43.

[0202] S35, in response to the first battery cluster completing the up-charge operation within the first preset duration, confirm that the first battery cluster is successfully up-charged.

[0203] S36, obtain the external sampling voltage of the first battery cluster and set it as the reference voltage.

[0204] S37, confirm whether there is a battery cluster in the other battery clusters of the up-chargeable group that satisfies “|internal sampling voltage-reference voltage|<first threshold”.

[0205] S38, if the result is yes, determine the battery cluster in the up-chargeable group that satisfies “|internal sampling voltage-reference voltage|<first threshold” as the second battery cluster.

[0206] S39, send the up-charge instruction to the second battery cluster, and also count the up-charge duration of the second battery cluster.

[0207] S40, confirm whether the second battery cluster completes the up-charge operation within the first preset duration.

[0208] S41, in response to the second battery cluster completing the up-charge operation within the first preset duration, confirm that the second battery cluster is successfully up-charged.

[0209] S42, in response to the second battery cluster not completing the up-charge operation within the first preset duration, confirm that the second battery cluster fails to be up-charged.

[0210] S43, in response to the first battery cluster not completing the up-charge operation within the first preset duration, confirm that the first battery cluster fails to be up-charged, and go to S44.

[0211] S44, re-sort the internal sampling voltages in the remaining battery clusters of the up-chargeable group, and determine the battery cluster in the middle position as the new first battery cluster, and return to S33.

[0212] In this context, the sending the power-up instruction specifically can mean that the control unit sends the power-up instruction to the master control unit of the battery cluster, and the master control unit controls the power-up of the corresponding battery cluster according to the control process shown in FIG. 6 in response to the power-up instruction.

[0213] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A control method of an energy storage system, wherein, The energy storage system comprises N branches and at least one energy storage converter, each of the branches is provided with a plurality of battery clusters independent of each other, the battery cluster comprises at least one battery pack, N is a positive integer greater than or equal to 2, each of the energy storage converters is electrically connected with K branches, and each of the branches can be charged or discharged through the corresponding energy storage converter, K is a positive integer, K is greater than or equal to 2 and less than or equal to N, and K branches are connected in parallel; The control method comprises: acquiring a power-on request; in response to the power-on request, acquiring state information of all the battery clusters on each branch, the state information at least comprising internal sampling voltage; and for any branch of the N branches, based on the state information of all the battery clusters on the branch, sending a power-on instruction to one of the battery clusters on the branch or to M battery clusters on the branch that satisfy voltage balance, M being a positive integer greater than or equal to 2, the voltage balance referring to that the difference between the internal sampling voltage of the remaining battery clusters and the reference voltage is less than a first threshold value, the reference voltage being the voltage value related to one of the M battery clusters, and the power-on instruction being used to instruct the corresponding battery cluster to perform a power-on operation.

2. The control method of an energy storage system according to claim 1, wherein, The method for any branch of the N branches, based on the state information of all the battery clusters on the branch, sending a power-on instruction to one of the battery clusters on the branch or to M battery clusters on the branch that satisfy voltage balance, comprises: for any branch of the N branches, based on the state information of all the battery clusters on the branch, determining a first battery cluster among all the battery clusters; sending the power-on instruction to the first battery cluster; in the case that the first battery cluster is powered on successfully, confirming whether there is a second battery cluster on the branch, the second battery cluster being in voltage balance with the first battery cluster, and the reference voltage being related to the first battery cluster; in response to the existence of the second battery cluster on the branch, sending the power-on instruction to the second battery cluster.

3. The control method of an energy storage system according to claim 2, wherein, The state information further comprises external sampling voltage; The method for any branch of the N branches, based on the state information of all the battery clusters on the branch, sending a power-on instruction to one of the battery clusters on the branch or to M battery clusters on the branch that satisfy voltage balance, comprises: in the case that the first battery cluster is powered on successfully, acquiring the reference voltage, the reference voltage being the external sampling voltage of the first battery cluster; judging whether the absolute value of the difference between the internal sampling voltage of any battery cluster of the remaining battery clusters on the branch and the reference voltage is less than the first threshold value; based on the judgment result, confirming whether there is the second battery cluster.

4. The control method of an energy storage system according to claim 2 or 3, wherein, Each of the branches is provided with at least three battery clusters; The method for determining a first battery cluster among all the battery clusters, comprises: determining the battery cluster with the internal sampling voltage arranged in the middle position among all the battery clusters as the first battery cluster.

5. The control method of an energy storage system according to any one of claims 1-4, wherein, The state information further comprises fault information; sending the power-up instruction to one of the battery clusters on the branch that meets the power-up allowed condition, or sending the power-up instruction to M battery clusters on the branch that meet the power-up allowed condition and voltage balance; wherein the power-up allowed condition includes a fault level lower than a first set level.

6. The control method of an energy storage system according to any one of claims 1-4, wherein, sending the power-up instruction to any one of the battery clusters while timing the power-up duration of the battery cluster; in response to the battery cluster completing the power-up operation within a first preset duration, confirming that the battery cluster is successfully powered up.

7. The control method of an energy storage system according to any one of claims 1-4, wherein, The state information further includes an external sampling voltage; The power-up instruction is configured to instruct the pre-charge circuit of the corresponding battery cluster to be powered up, and to obtain a pre-charge duration, an internal sampling voltage and the external sampling voltage of the battery cluster; to instruct to confirm whether the absolute value of the potential difference between the internal sampling voltage and the external sampling voltage of the corresponding battery cluster is less than a second threshold value within the second preset duration; further configured to instruct the main circuit of the battery cluster to be powered up and the pre-charge circuit to be disconnected when the absolute value of the potential difference between the internal sampling voltage and the external sampling voltage of the corresponding battery cluster is less than the second threshold value within the second preset duration.

8. The control method of an energy storage system according to any one of claims 1-7, wherein, After the step of sending the power-up instruction to one of the battery clusters on the branch that meets the power-up allowed condition, or sending the power-up instruction to M battery clusters on the branch that meet the power-up allowed condition and voltage balance, the method further includes: confirming whether the total number of battery clusters that are successfully powered up is greater than or equal to the minimum number of operating battery clusters; in response to the total number of battery clusters that are successfully powered up being greater than or equal to the minimum number of operating battery clusters, confirming that the energy storage system is powered up.

9. The control method of the energy storage system according to any one of claims 1-8, wherein, before the step of obtaining the power-up request, obtaining state information of all the battery clusters on the N branches, the state information further including fault information; based on the fault information of all the battery clusters, determining the fault level of each battery cluster; confirming whether the total number of battery clusters with a fault level lower than a second set level is greater than or equal to the minimum number of operating battery clusters; in response to the total number of battery clusters with a fault level lower than the second set level being greater than or equal to the minimum number of operating battery clusters, obtaining the power-up request.

10. An energy storage system, wherein, comprising: N branches, each of the branches being provided with a plurality of battery clusters, each of the battery clusters including at least one battery pack, N being a positive integer greater than or equal to 2; at least one energy storage converter, each of the energy storage converters being electrically connected to one of the branches or K branches connected in parallel, and each of the battery clusters of the branch being capable of being charged or discharged through the corresponding energy storage converter, K being a positive integer greater than or equal to 2 and less than or equal to N; and a control unit electrically connected to the at least one energy storage converter, the control unit being configured to implement the control method of the energy storage system according to any one of claims 1-9.

11. A computer device, wherein, comprising: at least one memory storing instructions; and at least one processor communicatively connected with the at least one memory, the at least one processor alone or collectively executing the instructions to implement the control method of the energy storage system as claimed in any one of claims 1-9.

12. A computer readable storage medium, wherein, instructions stored on the computer readable storage medium, the instructions being executed by one or more processors of a computer device, alone or collectively, to implement the control method of the energy storage system as claimed in any one of claims 1-9.

13. A computer program product, wherein, instructions, the instructions being executed by one or more processors of a computer device, alone or collectively, to implement the control method of the energy storage system as claimed in any one of claims 1-9.

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