Energy storage system, method for determining the number of sub-modules in an energy storage system, and electronic device

Abstract

The present application relates to an energy storage system, a method for determining the number of sub-modules in the energy storage system, and an electronic device, belonging to the technical field of power systems. The energy storage system includes: a valve bridge arm, the valve bridge arm includes a plurality of serially connected sub-modules, and the number of the plurality of sub-modules is related to the battery characteristics of the sub-modules. When determining the number of sub-modules in the energy storage system in the present application, the influence of the battery characteristics on the sub-modules is taken into account, so that the number of sub-modules in the energy storage system is related to the battery characteristics of the sub-modules, avoiding the problem that the number of redundant sub-modules is insufficient due to the influence of the battery characteristics during the operation of the energy storage system, resulting in a reduction in the fault tolerance and reliability of the energy storage system, and can improve the situation that the current energy storage system is prone to shut down due to the failure to meet the requirements of fault tolerance and reliability.

Description

Technical Field

[0001] The present application belongs to the technical field of power systems, and specifically relates to an energy storage system, a method for determining the number of submodules in the energy storage system, and an electronic device. Background Art

[0002] With the development of the power system, modular multi-level battery energy storage systems have gradually entered the demonstration application stage. The modular multi-level battery energy storage system includes a valve bridge arm, which generally includes multiple sub-modules. Each sub-module can be connected in series and / or in parallel. The sub-module generally integrates power electronic components such as capacitors and / or energy storage batteries. As those skilled in the art will understand, the sub-modules in the present disclosure play the role of storing electrical energy in the energy storage system. Since each component is relatively delicate and is a consumable item, the failure of the sub-module is inevitable during long-term operation. In order to avoid the failure of individual sub-modules affecting the normal operation of the system, additional redundant sub-modules can be configured during system design to replace the failed sub-modules. When one or more sub-modules fail, these failed sub-modules will not be put into use, and the redundant sub-modules will continue to perform normal work.

[0003] The inventors of the present application have discovered that, as the current energy storage system ages, its fault tolerance and reliability decrease, making it prone to shutdown due to failure to meet the requirements for fault tolerance and reliability. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide an energy storage system and a method and electronic device for determining the number of submodules in the energy storage system, so as to improve the problem that the current energy storage system is prone to shutdown due to failure to meet the requirements of fault tolerance and reliability.

[0005] The embodiment of the present application is implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides an energy storage system, comprising: a valve bridge arm, wherein the valve bridge arm comprises a plurality of submodules connected in series, and the number of the plurality of submodules is related to battery characteristics of the submodules.

[0007] In an embodiment of the present application, when determining the number of submodules in the energy storage system, the influence of battery characteristics on the submodules is taken into account, so that the number of submodules in the energy storage system is related to the battery characteristics of the submodules. This avoids the problem of insufficient number of redundant submodules (it should be noted that, for cost, volume, and other considerations, the number of redundant submodules needs to be determined more accurately) due to the influence of battery characteristics during operation of the energy storage system, which leads to reduced fault tolerance and reliability of the energy storage system. This can improve the situation in which current energy storage systems are prone to shutdown due to failure to meet fault tolerance and reliability requirements.

[0008] In a possible implementation manner combining the embodiments of the first aspect, the multiple sub-modules include: an initial sub-module and a redundant sub-module required for the normal operation of the energy storage system; wherein, the number of the redundant sub-modules is determined according to the number of the initial sub-modules, the failure rate of the sub-modules, and the voltage drop rate of the sub-modules; or, determined according to the number of the initial sub-modules, the failure rate of the sub-modules, the voltage drop rate of the sub-modules, and the system safety margin of the energy storage system, wherein the voltage drop rate of the sub-modules is related to the battery characteristics of the sub-modules.

[0009] In the embodiments of the present application, when determining the number of redundant sub-modules, in addition to the failure rate of the sub-modules, the voltage drop rate of the sub-modules related to the battery characteristics of the sub-modules needs to be considered. The number of redundant sub-modules determined by the method shown in the present application is more and more accurate compared with the number of redundant sub-modules determined only according to the failure rate of the sub-modules (it should be noted that, considering factors such as cost and volume, the number of redundant sub-modules needs to be determined more precisely), so as to alleviate the problem that the number of redundant sub-modules is insufficient due to the influence of battery characteristics during the operation of the energy storage system, resulting in the reduction of the fault tolerance and reliability of the energy storage system, and can improve the situation that the current energy storage system is prone to shutdown due to the failure to meet the requirements of fault tolerance and reliability.

[0010] In a possible implementation manner combining the embodiments of the first aspect, the voltage drop rate of the sub-module is determined according to the internal resistance growth rate of the battery when the sub-module is used until a specified period, the rated voltage of the battery, the rated current of the battery, and the initial internal resistance of the battery.

[0011] In the embodiments of the present application, the voltage drop rate of the sub-module is determined according to the internal resistance growth rate of the battery when the sub-module is used until a specified period, the rated voltage of the battery, the rated current of the battery, and the initial internal resistance of the battery, so that when determining the number of redundant sub-modules, the voltage drop rate caused by the internal resistance growth rate of the battery is taken into account. The number of redundant sub-modules determined in this way (it should be noted that, considering factors such as cost and volume, the number of redundant sub-modules needs to be determined more precisely) is more and more accurate, thus avoiding the insufficient number of redundant sub-modules due to the influence of battery characteristics.

[0012] In a possible implementation manner combining the embodiments of the first aspect, the redundant sub-modules include: a first redundant sub-module and a second redundant sub-module; the number of the first redundant sub-modules is determined according to the number of the initial sub-modules and the voltage drop rate of the sub-modules; the number of the second redundant sub-modules is determined according to the number of the initial sub-modules, the number of the first redundant sub-modules, and the failure rate of the sub-modules, or determined according to the number of the initial sub-modules and the failure rate of the sub-modules.

[0013] In the embodiments of the present application, the redundant sub-module includes a second redundant sub-module related to the failure rate and a first redundant sub-module related to the voltage drop rate. Compared with the existing method, the present application adds a first redundant sub-module related to the voltage drop rate. Moreover, when determining the number of the second redundant sub-modules, the influence of the voltage drop rate can also be taken into account, so that it can be determined according to the number of the initial sub-modules, the number of the first redundant sub-modules, and the failure rate of the sub-modules. By fully considering the influence of the battery characteristics on the sub-modules, the problem that the number of redundant sub-modules is insufficient due to the influence of the battery characteristics during the operation of the energy storage system, resulting in the reduction of the fault tolerance and reliability of the energy storage system, can be better alleviated.

[0014] Combined with a possible implementation manner of the first aspect embodiment, the number of the initial sub-modules is determined according to the total voltage of the energy storage system, the overvoltage level of the energy storage system, and the minimum voltage value of the sub-modules at different battery SOCs.

[0015] In the embodiments of the present application, when determining the number of the initial sub-modules, the influence of the battery characteristics (the voltage values of the battery are different at different SOCs (State of Charge, that is, the remaining battery charge)) on the sub-modules is taken into account, and the minimum voltage value of the sub-modules at different battery SOCs is used to determine the number of the initial sub-modules, so that the determined number of the initial sub-modules is more and more accurate than the number of the sub-modules determined by the existing method (using the rated voltage of the sub-modules). It should be noted that for reasons such as cost and volume, the number of redundant sub-modules needs to be determined more precisely. The redundant initial sub-modules can be used as redundant sub-modules, thereby alleviating the problem that as the service life of the current energy storage system increases, the fault tolerance and reliability of the energy storage system will decrease, and it is easy to stop operating due to the failure to meet the requirements of fault tolerance and reliability.

[0016] Combined with a possible implementation manner of the first aspect embodiment, the total number of sub-modules in the energy storage system is determined according to the number of redundant sub-modules, the number of initial sub-modules, and the number of valve bridge arms.

[0017] In the embodiments of the present application, according to the number of redundant sub-modules, the number of initial sub-modules, and the number of valve bridge arms, the total number of sub-modules in the energy storage system can be accurately determined. At the same time, when determining the total number of sub-modules in the energy storage system, the number of valve bridge arms is also taken into account, so that the method shown in the present application can be applied to energy storage systems with various valve bridge arms.

[0018] In a second aspect, an embodiment of the present application further provides a method for determining the number of sub-modules in an energy storage system, including: obtaining the number of redundant sub-modules in the energy storage system, and obtaining the number of initial sub-modules in the energy storage system, where the number of redundant sub-modules and / or the number of initial sub-modules are related to the battery characteristics of the sub-modules in the energy storage system; determining the total number of sub-modules in the energy storage system according to the number of redundant sub-modules and the number of initial sub-modules.

[0019] In a possible implementation manner combining with the embodiment of the second aspect, obtaining the number of redundant sub-modules in the energy storage system includes: obtaining the failure rate of the sub-modules in the energy storage system, and obtaining the voltage drop rate of the sub-modules in the energy storage system, where the voltage drop rate is related to the battery characteristics of the sub-modules in the energy storage system; determining the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system.

[0020] In a possible implementation manner combining with the embodiment of the second aspect, determining the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system includes: determining the number of first redundant sub-modules according to the number of initial sub-modules and the voltage drop rate of the sub-modules in the energy storage system; determining the number of second redundant sub-modules according to the number of initial sub-modules, the number of first redundant sub-modules, and the failure rate of the sub-modules in the energy storage system, or according to the number of initial sub-modules and the failure rate of the sub-modules in the energy storage system; determining the number of redundant sub-modules according to the number of first redundant sub-modules and the number of second redundant sub-modules.

[0021] In a possible implementation manner combining with the embodiment of the second aspect, the method further includes obtaining the system safety margin of the energy storage system; correspondingly, determining the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system includes: determining the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of the sub-modules in the energy storage system, the voltage drop rate of the sub-modules in the energy storage system, and the system safety margin.

[0022] In a possible implementation manner combining with the embodiment of the second aspect, obtaining the voltage drop rate of the sub-modules in the energy storage system includes: obtaining the internal resistance growth rate of the battery when the battery of the sub-module in the energy storage system is used to a specified period, the rated voltage of the battery, the rated current of the battery, and the initial internal resistance of the battery; determining the voltage drop rate of the sub-module according to the internal resistance growth rate, the rated voltage, the rated current, and the initial internal resistance.

[0023] In a possible implementation manner combining with the embodiments of the second aspect, obtaining the number of initial sub-modules in the energy storage system includes: determining the number of initial sub-modules according to the total voltage of the energy storage system, the overvoltage level of the energy storage system, and the minimum voltage value of the sub-modules in the energy storage system under different battery SOCs.

[0024] In a possible implementation manner combining with the embodiments of the second aspect, determining the total number of sub-modules in the energy storage system according to the number of redundant sub-modules and the number of initial sub-modules includes: determining the total number of sub-modules in the energy storage system according to the number of redundant sub-modules, the number of initial sub-modules, and the number of valve bridge arms of the energy storage system.

[0025] In a third aspect, an embodiment of the present application further provides a method for determining the number of sub-modules in an energy storage system, including: obtaining the failure rate of the sub-modules in the energy storage system, obtaining the voltage drop rate of the sub-modules in the energy storage system, where the voltage drop rate is related to the battery characteristics of the sub-modules in the energy storage system; determining the number of redundant sub-modules in the energy storage system according to the number of initial sub-modules required for the normal operation of the energy storage system, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system.

[0026] In a fourth aspect, an embodiment of the present application further provides a method for determining the number of sub-modules in an energy storage system, including: obtaining the number of initial sub-modules in the energy storage system; where the number of initial sub-modules is related to the battery characteristics of the sub-modules in the energy storage system; determining the total number of sub-modules in the energy storage system according to the number of initial sub-modules and the redundancy; where the redundancy is related to the battery characteristics of the sub-modules in the energy storage system.

[0027] In a fifth aspect, an embodiment of the present application further provides an electronic device, including: a memory for storing a program; a processor for calling the program stored in the memory to execute the method provided by the embodiments of the second aspect and / or any possible implementation manner combining with the embodiments of the second aspect, or to execute the method provided by the embodiments of the third aspect, or to execute the method provided by the embodiments of the fourth aspect.

[0028] Other features and advantages of the present application will be described in the subsequent specification. The objectives and other advantages of the present application can be achieved and obtained through the structures specifically pointed out in the written specification and the drawings. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. As shown in the drawings, the above-mentioned and other objects, features, and advantages of the present application will become clearer. The same reference numerals indicate the same parts in all the drawings. The drawings are not deliberately drawn to scale in actual size, and the focus is on showing the gist of the present application.

[0030] Figure 1 The flowchart of a method for determining the number of sub-modules in an energy storage system provided by an embodiment of the present application is shown.

[0031] Figure 2 The schematic diagram of the principle of the first method for determining the number of sub-modules in an energy storage system provided by an embodiment of the present application is shown.

[0032] Figure 3 The schematic diagram of the principle of the second method for determining the number of sub-modules in an energy storage system provided by an embodiment of the present application is shown.

[0033] Figure 4 The schematic diagram of the principle of the third method for determining the number of sub-modules in an energy storage system provided by an embodiment of the present application is shown.

[0034] Figure 5 The schematic diagram of the principle of the fourth method for determining the number of sub-modules in an energy storage system provided by an embodiment of the present application is shown.

[0035] Figure 6 The schematic diagram of the principle of the fifth method for determining the number of sub-modules in an energy storage system provided by an embodiment of the present application is shown.

[0036] Figure 7 The flowchart of the second method for determining the number of sub-modules in an energy storage system provided by an embodiment of the present application is shown.

[0037] Figure 8 The flowchart of the third method for determining the number of sub-modules in an energy storage system provided by an embodiment of the present application is shown.

[0038] Figure 9 The schematic diagram of the structure of the first energy storage system provided by an embodiment of the present application is shown.

[0039] Figure 10 The schematic diagram of the structure of the second energy storage system provided by an embodiment of the present application is shown.

[0040] Figure 11 The schematic diagram of the structure of the third energy storage system provided by an embodiment of the present application is shown.

[0041] Figure 12 The schematic diagram of the structure of an electronic device provided by an embodiment of the present application is shown. Detailed implementation manners

[0042] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0043] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present application, relational terms such as "first", "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0044] Furthermore, the term "and / or" in the present application is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three cases: A exists alone, A and B exist simultaneously, and B exists alone.

[0045] Currently, from the perspective of the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in multiple fields such as military equipment and aerospace. Moreover, they are also used in energy storage systems such as hydroelectric, thermal, wind, and solar power stations.

[0046] In view of the fact that as the service life of the current energy storage system increases, the fault tolerance and reliability of the energy storage system will decrease, and it is easy to occur the situation of shutdown due to the failure to meet the requirements of fault tolerance and reliability. The inventor of the present application found that the reason for this situation is that when designing the redundancy of the redundant sub-module of the energy storage system currently, it is only determined according to the failure rate of the sub-module, resulting in insufficient number of redundant sub-modules (it should be noted that due to considerations such as cost and volume, the number of redundant sub-modules needs to be determined more precisely and cannot be set arbitrarily) during the operation of the energy storage system, thus reducing the fault tolerance and reliability of the energy storage system. The inventor of the present application found that the performance of the energy storage system will be affected by the battery characteristics of the sub-modules in the energy storage system. Since the number of sub-modules in the energy storage system is not considered the battery characteristics when designing currently, during the operation of the energy storage system, the number of redundant sub-modules is insufficient due to the influence of the battery characteristics, thereby reducing the fault tolerance and reliability of the energy storage system.

[0047] Among them, the battery has the following characteristics: 1. As the service life increases, the internal resistance of the battery will gradually increase, resulting in a gradual decrease in the terminal voltage of the battery, that is, voltage drop will occur; 2. The voltage values of the battery are different at different SOC (State of Charge, remaining battery charge).

[0048] To solve the problem that as the service life of the current energy storage system increases, the fault tolerance and reliability of the energy storage system decrease. The embodiment of the present application provides a brand-new method for determining the number of sub-modules in the energy storage system. When determining the number of sub-modules in the energy storage system, this method takes into account the influence of battery characteristics on the sub-modules, thereby ensuring that the energy storage system meets the requirements of safe operation throughout the life cycle and solving the problem that as the service life of the current energy storage system increases, the fault tolerance and reliability of the energy storage system decrease. For better understanding, the following will be combined with Figure 1 to illustrate the method for determining the number of sub-modules in the energy storage system provided by the embodiment of the present application.

[0049] S1: Obtain the number of redundant sub-modules in the energy storage system, and obtain the number of initial sub-modules in the energy storage system.

[0050] To ensure the efficient and safe operation of the energy storage system, when determining the number of sub-modules in the energy storage system, it is necessary to obtain the number of redundant sub-modules and the number of initial sub-modules in the energy storage system respectively. In this application, when determining the number of redundant sub-modules and / or initial sub-modules, the influence of battery characteristics on the sub-modules in the energy storage system is taken into account, so that the number of redundant sub-modules and / or initial sub-modules is related to the battery characteristics of the sub-modules in the energy storage system. That is to say, when determining the number of redundant sub-modules, the influence of battery characteristics on the sub-modules in the energy storage system can be taken into account, so that the number of redundant sub-modules is related to the battery characteristics of the sub-modules in the energy storage system; it can also be when determining the number of initial sub-modules, the influence of battery characteristics on the sub-modules in the energy storage system is taken into account, so that the number of initial sub-modules is related to the battery characteristics of the sub-modules in the energy storage system; or, when determining the number of initial sub-modules and redundant sub-modules, the influence of battery characteristics on the sub-modules in the energy storage system is taken into account, so that the numbers of both initial sub-modules and redundant sub-modules are related to the battery characteristics of the sub-modules in the energy storage system.

[0051] It can be understood that redundant sub-modules and initial sub-modules are essentially both sub-modules (Sub Module, SM). Redundant sub-modules are relative to initial sub-modules. For example, assume that the energy storage system includes 10 sub-modules, and assume that 6 sub-modules are required for the normal operation of the energy storage system. Then the remaining 4 sub-modules are redundant sub-modules. And the 6 sub-modules required for the normal operation of the energy storage system are the initial sub-modules. During operation, the system calls 6 out of 10 sub-modules according to a specific control strategy, and the called sub-modules are not specific certain modules.

[0052] The sub-modules in this application can refer to the sub-modules included in the valve bridge arm of the energy storage system, where the valve bridge arm includes a plurality of serially connected sub-modules. The structures of the plurality of sub-modules can be all the same or partially the same. For example, the plurality of sub-modules can all be half-bridge energy storage sub-modules, or all be full-bridge energy storage sub-modules, or some are half-bridge energy storage sub-modules and some are full-bridge energy storage sub-modules.

[0053] In the first implementation manner, when obtaining the number of redundant sub-modules in the energy storage system, the process can be as follows: First, obtain the failure rate of the sub-modules in the energy storage system and the voltage drop rate of the sub-modules in the energy storage system. Then, determine the number of redundant sub-modules based on the number of initial sub-modules, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system. Among them, the voltage drop rate is related to the battery characteristics of the sub-modules in the energy storage system. For example, as the service life increases, the internal resistance of the battery gradually increases, resulting in a gradual decrease in the terminal voltage of the battery, that is, voltage drop occurs. Compared with the existing energy storage system, in the embodiment of the present application, when determining the number of redundant sub-modules, in addition to considering the failure rate of the sub-modules, the voltage drop rate of the sub-modules caused by the battery characteristics is also taken into account.

[0054] Optionally, when determining the number of redundant sub-modules based on the number of initial sub-modules, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system, the process can be as follows: Determine the number of the first redundant sub-modules based on the number of initial sub-modules and the voltage drop rate of the sub-modules in the energy storage system; determine the number of the second redundant sub-modules based on the number of initial sub-modules and the failure rate of the sub-modules in the energy storage system; determine the number of redundant sub-modules based on the number of the first redundant sub-modules and the number of the second redundant sub-modules. Assume that the number of initial sub-modules is N0, the number of the first redundant sub-modules is N1, the number of the second redundant sub-modules is N2, and the number of redundant sub-modules is N. Then, N1 = N0 * voltage drop rate, N2 = N0 * failure rate. At this time, N = N1 + N2. It can be understood that if the value of N0 * voltage drop rate and / or N0 * failure rate is a non-integer, it can be rounded up.

[0055] Optionally, when determining the number of redundant sub-modules based on the number of initial sub-modules, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system, the process can be as follows: Determine the number of the first redundant sub-modules based on the number of initial sub-modules and the voltage drop rate of the sub-modules in the energy storage system; determine the number of the second redundant sub-modules based on the number of initial sub-modules, the number of the first redundant sub-modules, and the failure rate of the sub-modules in the energy storage system; determine the number of redundant sub-modules based on the number of the first redundant sub-modules and the number of the second redundant sub-modules. Assume that the number of initial sub-modules is N0, the number of the first redundant sub-modules is N1, the number of the second redundant sub-modules is N2, and the number of redundant sub-modules is N. Then, N1 = N0 * voltage drop rate, N2 = (N0 + N1) * failure rate. At this time, N = N1 + N2. It can be understood that if the value of N0 * voltage drop rate and / or (N0 + N1) * failure rate is a non-integer, it can be rounded up.

[0056] Optionally, the failure rate of the sub-module and the voltage drop rate of the sub-module can be determined in advance and directly obtained when needed, which can improve the acquisition efficiency. The existing method can be used to determine the failure rate of the sub-module.

[0057] Among them, the process of obtaining the voltage drop rate of the sub-module in the energy storage system can be as follows: obtain the internal resistance growth rate of the battery of the sub-module in the energy storage system when it is used until the specified period, the rated voltage of the battery, the rated current of the battery, and the initial internal resistance of the battery; determine the voltage drop rate of the sub-module according to the internal resistance growth rate, rated voltage, rated current, and initial internal resistance. Assuming that the rated voltage of the battery is 3.2V, the initial internal resistance is 0.75mΩ = 0.00075Ω, the rated current is 200A, and the internal resistance growth rate is 40%, and these parameters are all basic performance parameters of the battery, then the voltage of the battery when it is used until the specified period can be calculated as: (3.2 - 0.75 * 40% * 200 / 1000)V = (3.2 - 0.06)V = 3.14V, and the corresponding voltage drop rate is (1 - 3.14 / 3.2) * 100% ≈ 2%.

[0058] It can be understood that the internal resistance growth rate of the battery of the sub-module obtained here can be the internal resistance growth rate of the battery in the sub-module when the existing energy storage system using the same sub-module is used until the specified period.

[0059] The above-mentioned specified period can be the end of the battery life or the end of the battery use. The end of the life refers to the end of the normal life of the battery. For example, assuming that the normal life of the battery is 10 years, then the end of the battery life can be 10 years. The end of the use can refer to the period when the battery reaches the specified service life (generally less than or equal to the life limit). For example, when the remaining available capacity of the battery is lower than the preset lower limit value, it is considered that the battery reaches the specified service life. Assuming that the preset lower limit value of the battery is 80% of the available capacity of the battery, and assuming that the normal life of the battery is 10 years (the lower limit of the remaining available capacity is 60%), then it is possible that the remaining available capacity of the battery reaches 80% of the available capacity of the battery in the 6th year. Although it has not reached the normal life time of the battery at this time, it has reached the specified service life of the battery.

[0060] In the second implementation manner, the existing method can also be used to obtain the number of redundant sub-modules in the energy storage system. For example, when obtaining the number of redundant sub-modules in the energy storage system, the process can be as follows: obtain the failure rate of the sub-modules in the energy storage system, and determine the number of redundant sub-modules according to the number of initial sub-modules and the failure rate of the sub-modules in the energy storage system. For example, assuming that the number of initial sub-modules is N0 and the number of redundant sub-modules is N, at this time, N = N0 * the failure rate of the sub-module. It can be understood that if the value of N0 * the failure rate is a non-integer, it can be rounded up.

[0061] Considering that in order for the energy storage system to operate safely, a system safety margin, i.e., a system safety factor, is usually set as a constant. Therefore, when determining the number of redundant sub-modules, whether using the first implementation method or the second implementation method described above to determine the number of redundant sub-modules, the system safety margin can be taken into account.

[0062] When considering the system safety margin of the energy storage system, at this time, the process of determining the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of sub-modules in the energy storage system, and the voltage drop rate of sub-modules in the energy storage system is as follows: Determine the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of sub-modules in the energy storage system, the voltage drop rate of sub-modules in the energy storage system, and the system safety margin. At this time, the number of redundant sub-modules (assumed to be N') = N * system safety margin.

[0063] When considering the system safety margin of the energy storage system, at this time, the process of determining the number of redundant sub-modules according to the number of initial sub-modules and the failure rate of sub-modules in the energy storage system is as follows: Determine the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of sub-modules in the energy storage system, and the system safety margin. At this time, the number of redundant sub-modules (assumed to be N') = N * system safety margin.

[0064] In the first implementation method, when obtaining the number of initial sub-modules, it can be determined by the first method the number of initial sub-modules required for the normal operation of the energy storage system (at this time, the influence of battery characteristics on the initial sub-modules is not considered), or it can be determined by the method shown in this application that takes into account the influence of battery characteristics on the initial sub-modules in the energy storage system (simply referred to as the second method) to determine the number of initial sub-modules required for the normal operation of the energy storage system.

[0065] In the second implementation method, since the influence of battery characteristics on the redundant sub-modules in the energy storage system is not considered when determining the number of redundant sub-modules at this time, therefore, when determining the number of initial sub-modules required for the normal operation of the energy storage system, the influence of battery characteristics on the initial sub-modules in the energy storage system needs to be taken into account, that is, the second method needs to be used to determine the number of redundant sub-modules. At this time, the number of initial sub-modules determined is more than the number of initial sub-modules determined by the first method. The extra initial sub-modules can be used as redundant sub-modules. Therefore, the total number of sub-modules finally determined is more than the total number of sub-modules determined by the first method, which can also alleviate the situation that as the service life of the current energy storage system increases, the fault tolerance and reliability of the energy storage system will decrease, and it is easy to stop operating due to the failure to meet the requirements of fault tolerance and reliability.

[0066] The first method to obtain the number of initial sub - modules can be to determine the number of initial sub - modules based on the total voltage of the energy storage system, the over - voltage level of the energy storage system, and the rated voltage of the sub - modules in the energy storage system. Then the number of initial sub - modules \(N_0=\frac{\text{total voltage}\times\text{over - voltage level}}{\text{rated voltage}}\). For example, assuming the total voltage of the energy storage system is \(70\ kV\), the over - voltage level is \(1.1\), and the rated voltage is \(1.5\ kV\), then the number of initial sub - modules \(N_0 = 70\times1.1 / 1.5=52\). It can be understood that if the value of \(\frac{\text{total voltage}\times\text{over - voltage level}}{\text{rated voltage}}\) is a non - integer, it can be rounded up. For example, \(5.1\) rounded up is \(6\).

[0067] The second method to obtain the number of initial sub - modules can be to determine the number of initial sub - modules based on the total voltage of the energy storage system, the over - voltage level of the energy storage system, and the minimum voltage value of the sub - modules in the energy storage system at different battery SOCs. Then the number of initial sub - modules \(N_0=\frac{\text{total voltage}\times\text{over - voltage level}}{\text{minimum voltage value}}\). For example, assuming the total voltage of the energy storage system is \(70\ kV\), the over - voltage level is \(1.1\), and the minimum voltage value is \(1.2\ kV\), then the number of initial sub - modules \(N_0 = 70\times1.1 / 1.2 = 65\). It can be understood that if the value of \(\frac{\text{total voltage}\times\text{over - voltage level}}{\text{minimum voltage value}}\) is a non - integer, it can be rounded up.

[0068] When obtaining the number of initial sub - modules, compared with the first method, in the second method, it is the minimum voltage value of the sub - modules in the energy storage system at different battery SOCs that is used to determine the number of initial sub - modules, rather than the rated voltage value for calculation. By taking into account the influence of battery characteristics on the initial sub - modules in the energy storage system, that is, considering that the voltage values of the battery are different at different SOCs, it can be ensured that the energy storage system meets the requirements of safe operation throughout its life cycle.

[0069] S2: Determine the total number of sub - modules in the energy storage system according to the number of redundant sub - modules and the number of initial sub - modules.

[0070] After obtaining the number of redundant sub - modules (assumed to be \(N'\)) and the number of initial sub - modules (assumed to be \(N_0\)), the total number of sub - modules in the energy storage system can be determined according to the number of redundant sub - modules and the number of initial sub - modules. The total number of sub - modules in the energy storage system \(=N'+N_0\).

[0071] Considering that some energy storage systems include multiple (two or more) valve bridge arms, therefore, in one implementation, the process of determining the total number of sub-modules in the energy storage system according to the number of redundant sub-modules and the number of initial sub-modules can be: determine the total number of sub-modules in the energy storage system according to the number of redundant sub-modules, the number of initial sub-modules, and the number of valve bridge arms (assumed to be n) of the energy storage system. At this time, the total number of sub-modules in the energy storage system = (N'+N0) * the number of valve bridge arms n.

[0072] For better understanding, the following combines Figures 2 - 6 , and explains the principle of the method for determining the number of sub-modules in the energy storage system provided by the embodiments of the present application.

[0073] In Figure 2 , Figure 3 , the first method described above is used to determine the number of initial sub-modules. At this time, the first implementation described above is used to determine the number of redundant sub-modules. Figure 2 Compared with Figure 3 , the difference is that when determining the number of second redundant sub-modules, Figure 2 it is directly calculated according to the failure rate of the sub-modules. Figure 3 It also takes into account the change in the number of sub-modules caused by the voltage drop rate.

[0074] In Figure 4 , Figure 5 , the second method described above is used to determine the number of initial sub-modules. At this time, the first implementation described above is also used to determine the number of redundant sub-modules. Figure 5 Compared with Figure 4 , the difference is that when determining the number of second redundant sub-modules, Figure 5 it is directly calculated according to the failure rate of the sub-modules. Figure 4 It also takes into account the change in the number of sub-modules caused by the voltage drop rate.

[0075] In Figure 6 , the second method described above is used to determine the number of initial sub-modules. At this time, the second implementation described above is used to determine the number of redundant sub-modules. Figure 6 Compared with Figure 2 or Figure 3 , although Figure 6 when determining the number of redundant sub-modules, the influence brought by the battery characteristics is not considered, resulting in the number of redundant sub-modules (which is 10 at this time) being less than Figure 2 or Figure 3 the number of redundant sub-modules in Figure 6 (which is 13 at this time), it can be seen that since Figure 6The number of initial sub - modules at this time (65) is significantly greater than Figure 2 or Figure 3 the number of initial sub - modules at this time (52). The extra 13 (65 - 52) initial sub - modules can be used as redundant sub - modules when the voltage of the sub - modules is relatively high. It should be noted that the 52 sub - modules called during operation are not fixed modules.

[0076] Compared with the number of sub - modules in the energy storage system determined by the existing method that does not consider battery characteristics (at this time, the number of initial sub - modules is 52 + the number of redundant sub - modules is 10), the number of sub - modules in the energy storage system determined by the method shown in this application, that is, the number of sub - modules in the energy storage system in Figures 2 - 6 above, is greater than the number of sub - modules in the energy storage system determined by the existing method that does not consider battery characteristics. Therefore, the defects existing in the existing storage system can be well alleviated.

[0077] It can be understood that Figures 2 - 6 the example shown is for an energy storage system with only one valve bridge arm. When the number of valve bridge arms in the energy storage system is multiple, at this time, the number of sub - modules in the energy storage system=(N’ + N0)* the number of valve bridge arms.

[0078] Based on the same inventive concept, the embodiment of this application also provides a method for determining the number of sub - modules in an energy storage system, as shown in Figure 7 below. The method provided by the embodiment of this application will be described in combination with Figure 7 below.

[0079] S10: Obtain the number of initial sub - modules in the energy storage system; wherein, the number of initial sub - modules is related to the battery characteristics of the sub - modules in the energy storage system.

[0080] When obtaining the number of initial sub - modules in the energy storage system, it can be determined according to the total voltage of the energy storage system, the over - voltage level of the energy storage system, and the minimum voltage value of the sub - modules in the energy storage system at different battery SOCs. Then the number of initial sub - modules N0 = total voltage * over - voltage level / minimum voltage value. By taking into account the influence of battery characteristics on the initial sub - modules in the energy storage system, that is, considering the different voltage values of the battery at different SOCs, the safe operation requirements of the energy storage system can be ensured throughout the entire life cycle.

[0081] S20: Determine the total number of sub - modules in the energy storage system according to the number of initial sub - modules and the redundancy; wherein, the redundancy is related to the battery characteristics of the sub - modules in the energy storage system.

[0082] After obtaining the number of initial sub-modules in the energy storage system, based on the number of initial sub-modules and the redundancy, the total number of sub-modules in the energy storage system can be determined. The total number of sub-modules in the energy storage system = the number of initial sub-modules * (1 + redundancy).

[0083] In an alternative implementation, when determining the total number of sub-modules in the energy storage system according to the number of initial sub-modules and the redundancy, the number of valve bridge arms is also taken into consideration. At this time, the process can be to determine the total number of sub-modules in the energy storage system according to the number of initial sub-modules, the number of valve bridge arms and the redundancy. At this time, the total number of sub-modules in the energy storage system = the number of initial sub-modules * (1 + redundancy) * the number of valve bridge arms.

[0084] The redundancy is estimated based on empirical data and generally does not exceed 30%, which is used for quickly or preliminarily estimating the total number of sub-modules in the energy storage system. In this application, when estimating the redundancy, the influence of battery characteristics on the sub-modules in the energy storage system is taken into consideration, so that the redundancy is related to the battery characteristics of the sub-modules in the energy storage system. Redundancy = the number of redundant sub-modules / the number of initial sub-modules * 100%. The redundancy can be estimated in advance according to the number of redundant sub-modules and the total number of sub-modules in the existing energy storage system. After that, when designing a similar existing energy storage system, the total number of sub-modules in the energy storage system can be quickly or preliminarily estimated directly based on this redundancy.

[0085] Among them, the number of redundant sub-modules can also be related to the battery characteristics of the sub-modules in the energy storage system. For this part of the content, reference can be made to the corresponding content above and will not be elaborated here.

[0086] Based on the same inventive concept, the embodiment of this application also provides a method for determining the number of sub-modules in an energy storage system, as Figure 8 shown. The following will be combined with Figure 7 to illustrate the method in the embodiment of this application.

[0087] S100: Obtain the failure rate of the sub-modules in the energy storage system and obtain the voltage drop rate of the sub-modules in the energy storage system.

[0088] When determining the number of sub-modules in the energy storage system, for example, when determining the number of redundant sub-modules in the energy storage system, obtain the failure rate of the sub-modules in the energy storage system and obtain the voltage drop rate of the sub-modules in the energy storage system, where the voltage drop rate is related to the battery characteristics of the sub-modules in the energy storage system.

[0089] Optionally, the failure rate of the sub-modules and the voltage drop rate of the sub-modules can be determined in advance and directly obtained when needed, which can improve the acquisition efficiency.

[0090] S200: Determine the number of redundant sub-modules in the energy storage system according to the number of initial sub-modules required for the normal operation of the energy storage system, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system.

[0091] After obtaining the failure rate of the sub-modules in the energy storage system and the voltage drop rate of the sub-modules in the energy storage system, the number of redundant sub-modules in the energy storage system can be determined accordingly. When determining the number of redundant sub-modules in the energy storage system, it can be based on the number of initial sub-modules required for the normal operation of the energy storage system, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system to determine the number of redundant sub-modules in the energy storage system. For this process, please refer to the above process of determining the number of redundant sub-modules in the energy storage system according to the number of initial sub-modules required for the normal operation of the energy storage system, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system.

[0092] In addition, when determining the number of redundant sub-modules in the energy storage system, the system safety margin of the energy storage system (i.e., the system safety factor, which is a constant) can also be taken into consideration. At this time, the process of determining the number of redundant sub-modules in the energy storage system according to the number of initial sub-modules required for the normal operation of the energy storage system, the failure rate of the sub-modules in the energy storage system, and the voltage drop rate of the sub-modules in the energy storage system is: Determine the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of the sub-modules in the energy storage system, the voltage drop rate of the sub-modules in the energy storage system, and the system safety margin.

[0093] Among them, the number of initial sub-modules required for the normal operation of the energy storage system can be determined by using the above first method or the above second method.

[0094] Among them, Figure 8 For the parts not introduced in the embodiments, please refer to Figure 1 the introduction of the same parts in the embodiments.

[0095] After determining the number of sub-modules in the energy storage system according to the above method, the energy storage system can be designed according to the determined number of sub-modules. Therefore, based on the same inventive concept, the embodiments of the present application also provide an energy storage system, which includes a valve bridge arm. The valve bridge arm includes a plurality of sub-modules connected in series, and the number of these sub-modules is related to the battery characteristics of the sub-modules. In the embodiments of the present application, when designing the number of sub-modules included in the valve bridge arm, the battery characteristics in the sub-modules are taken into consideration, so that the number of sub-modules in the determined energy storage system is related to the battery characteristics of the sub-modules. Compared with the method that does not consider the battery characteristics, the number of sub-modules included in the valve bridge arm in the present application will be more and more accurate.

[0096] The multiple sub - modules included in the valve bridge arm include: the initial sub - modules required for the normal operation of the energy storage system and the redundant sub - modules.

[0097] In the first implementation mode, the number of redundant sub - modules can be determined according to the number of initial sub - modules, the failure rate of the sub - modules, and the voltage drop rate of the sub - modules; or, according to the number of initial sub - modules, the failure rate of the sub - modules, the voltage drop rate of the sub - modules, and the system safety margin of the energy storage system. The voltage drop rate of the sub - modules is related to the battery characteristics of the sub - modules. For example, according to the number of initial sub - modules and the voltage drop rate of the sub - modules, determine the number of the first redundant sub - modules; according to the number of initial sub - modules, the number of the first redundant sub - modules, and the failure rate of the sub - modules, or, according to the number of initial sub - modules and the failure rate of the sub - modules, determine the number of the second redundant sub - modules. Then, according to the number of the first redundant sub - modules and the number of the second redundant sub - modules, or, according to the number of the first redundant sub - modules, the number of the second redundant sub - modules, and the system safety margin, determine the number of redundant sub - modules.

[0098] In the first implementation mode, the redundant sub - modules include: the first redundant sub - modules and the second redundant sub - modules. When not considering the system safety margin of the energy storage system, the number of redundant sub - modules = the number of the first redundant sub - modules+the number of the second redundant sub - modules. When considering the system safety margin of the energy storage system, the number of redundant sub - modules=(the number of the first redundant sub - modules+the number of the second redundant sub - modules)*system safety margin.

[0099] Among them, the number of the first redundant sub - modules can be determined according to the number of initial sub - modules and the voltage drop rate of the sub - modules. For example, assume that the number of initial sub - modules is N0 and the number of the first redundant sub - modules is N1, then N1 = N0*the voltage drop rate of the sub - modules.

[0100] The number of the second redundant sub - modules can be determined according to the number of initial sub - modules, the number of the first redundant sub - modules, and the failure rate of the sub - modules, or, according to the number of initial sub - modules and the failure rate of the sub - modules. For example, assume that the number of initial sub - modules is N0, the number of the first redundant sub - modules is N1, and the number of the second redundant sub - modules is N2, N2 = N0*the failure rate of the sub - modules, or, N2=(N0 + N1)*the failure rate of the sub - modules.

[0101] In the second implementation mode, the number of redundant sub-modules can be determined according to the number of initial sub-modules and the failure rate of the sub-modules; or, it can be determined according to the number of initial sub-modules, the failure rate of the sub-modules, and the system safety margin of the energy storage system. If the voltage drop rate of the sub-modules is not considered, the redundant sub-modules only include the second redundant sub-modules. When the system safety margin of the energy storage system is not considered, the redundant sub-modules = the second redundant sub-modules. When the system safety margin of the energy storage system is considered, the number of redundant sub-modules = the number of the second redundant sub-modules * the system safety margin.

[0102] In the second implementation mode, the number of the second redundant sub-modules can be determined according to the number of initial sub-modules and the failure rate of the sub-modules. Suppose the number of initial sub-modules is N0 and the number of the second redundant sub-modules is N2, then N2 = N0 * the failure rate of the sub-modules.

[0103] Optionally, the voltage drop rate of the sub-modules is determined according to the internal resistance growth rate of the battery when the battery of the sub-module is used up to the specified period, the rated voltage of the battery, the rated current of the battery, and the initial internal resistance of the battery. Suppose, taking the rated voltage of the battery as 3.2V, the initial internal resistance as 0.75mΩ = 0.00075Ω, the rated current as 200A, and the internal resistance growth rate as 40% as an example, and these parameters are all basic performance parameters of the battery, then the voltage of the battery when it is used up to the specified period can be calculated as: (3.2 - 0.75 * 40% * 200 / 1000)V = (3.2 - 0.06)V = 3.14V, and the corresponding voltage drop rate is (1 - 3.14 / 3.2) * 100% ≈ 2%.

[0104] Similarly, when determining the number of initial sub-modules, there are also two ways to determine it. The first way does not consider the influence of battery characteristics on the initial sub-modules, and the first way considers the influence of battery characteristics on the initial sub-modules.

[0105] In the first way, the number of initial sub-modules can be determined according to the total voltage of the energy storage system, the overvoltage level of the energy storage system, and the rated voltage of the sub-modules. For example, the number of initial sub-modules N0 = the total voltage of the energy storage system * the overvoltage level / the minimum voltage value.

[0106] In the second way, the number of initial sub-modules can be determined according to the total voltage of the energy storage system, the overvoltage level of the energy storage system, and the minimum voltage value of the sub-modules under different battery SOCs. For example, the number of initial sub-modules N0 = the total voltage of the energy storage system * the overvoltage level / the minimum voltage value.

[0107] In one implementation mode, the number of valve bridge arms can be 1. At this time, the energy storage system is a directly-connected energy storage system, and its schematic diagram is as Figure 9 shown. It can be understood that Figure 9The example diagram shown is only a part of the energy storage system, and only the part related to the valve bridge arm is shown. It can be seen that in addition to including multiple series-connected sub-modules (SM), the valve bridge arm can also include devices such as reactors connected in series with the sub-modules. The valve bridge arm is connected in series between the positive pole and the negative pole of the DC bus. At this time, the total number of sub-modules in the energy storage system = the number of redundant sub-modules + the number of initial sub-modules.

[0108] When the energy storage system includes multiple valve bridge arms, for example, as Figure 10 , Figure 11 shown in the schematic diagram, it includes multiple valve bridge arms. At this time, the total number of sub-modules in the energy storage system is determined according to the number of redundant sub-modules, the number of initial sub-modules, and the number of valve bridge arms. For example, the total number of sub-modules in the energy storage system = (the number of redundant sub-modules + the number of initial sub-modules) * the number of valve bridge arms. For Figure 10 , when determining the total number of sub-modules in the energy storage system, the number of valve bridge arms is 6; for Figure 11 , when determining the total number of sub-modules in the energy storage system, the number of valve bridge arms is 3.

[0109] The energy storage system provided by the embodiments of the present application has the same implementation principle and technical effects as those of the foregoing method embodiments. For the sake of brief description, for the parts not mentioned in the system embodiments, reference can be made to the corresponding content in the foregoing method embodiments. For example, when determining the number of initial sub-modules and redundant sub-modules in the energy storage system, the principle shown above Figures 2 - 6 can be used for determination.

[0110] Based on the same inventive concept, the embodiments of the present application also provide an electronic device, as Figure 12 shown, Figure 12 shows a structural block diagram of an electronic device 100 provided by the embodiments of the present application. The electronic device 100 includes: a transceiver 110, a memory 120, a communication bus 130, and a processor 140.

[0111] The transceiver 110, the memory 120, and the processor 140 are electrically connected to each other directly or indirectly to enable data transmission or interaction. For example, these components can be electrically connected to each other via one or more communication buses 130 or signal lines. The transceiver 110 is used to send and receive data. The memory 120 is used to store computer programs or software function modules. These computer programs or software function modules include at least one software function module that can be stored in the memory 120 in the form of software or firmware or embedded in the operating system (OS) of the electronic device 100. The processor 140 is used to execute the software function modules or computer programs stored in the memory 120. For example, the processor 140 is used to obtain the number of redundant submodules in the energy storage system and the number of initial submodules in the energy storage system; the number of redundant submodules and / or the number of initial submodules are related to the battery characteristics of the submodules in the energy storage system; and the total number of submodules in the energy storage system is determined based on the number of redundant submodules and the number of initial submodules.

[0112] Alternatively, the processor 140 is configured to obtain a failure rate of a submodule in the energy storage system and a voltage drop rate of the submodule in the energy storage system, wherein the voltage drop rate is related to battery characteristics of the submodule in the energy storage system; and determine the number of redundant submodules in the energy storage system based on the number of initial submodules required for normal operation of the energy storage system, the failure rate of the submodule in the energy storage system, and the voltage drop rate of the submodule in the energy storage system.

[0113] Alternatively, the processor 140 is configured to obtain an initial number of submodules in the energy storage system, where the initial number of submodules is related to battery characteristics of the submodules in the energy storage system; and determine a total number of submodules in the energy storage system based on the initial number of submodules and redundancy, where the redundancy is related to battery characteristics of the submodules in the energy storage system.

[0114] The memory 120 may be, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc.

[0115] The processor 140 may be an integrated circuit chip with the ability to process signals. The above-mentioned processor may be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or the processor 140 may also be any conventional processor, etc.

[0116] Among them, the above-mentioned electronic device 100 includes, but is not limited to, mobile phones, tablets, computers, servers, etc.

[0117] It should be noted that the various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0118] As mentioned above, the above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An energy storage system, characterized in that, Including: A valve bridge arm, which includes a plurality of sub - modules connected in series; wherein, the number of the plurality of sub - modules is related to the battery characteristics of the sub - modules; The plurality of sub - modules include: an initial sub - module and redundant sub - modules required for the normal operation of the energy storage system; Wherein, the number of the redundant sub - modules is determined according to the number of the initial sub - modules, the failure rate of the sub - modules, and the voltage drop rate of the sub - modules; or, determined according to the number of the initial sub - modules, the failure rate of the sub - modules, the voltage drop rate of the sub - modules, and the system safety margin of the energy storage system; wherein, the voltage drop rate of the sub - modules is related to the battery characteristics of the sub - modules; The voltage drop rate of the sub - modules is determined according to the internal resistance growth rate of the battery when the battery of the sub - module is used to a specified period, the rated voltage of the battery, the rated current of the battery, and the initial internal resistance of the battery.

2. The energy storage system according to claim 1, characterized in that The redundant sub - modules include: a first redundant sub - module and a second redundant sub - module; The number of the first redundant sub - modules is determined according to the number of the initial sub - modules and the voltage drop rate of the sub - modules; The number of the second redundant sub - modules is determined according to the number of the initial sub - modules, the number of the first redundant sub - modules, and the failure rate of the sub - modules, or determined according to the number of the initial sub - modules and the failure rate of the sub - modules.

3. The energy storage system according to claim 1, characterized in that, The number of the initial sub - modules is determined according to the total voltage of the energy storage system, the over - voltage level of the energy storage system, and the minimum voltage value of the sub - modules at different battery SOCs.

4. The energy storage system according to any one of claims 1-3, characterized in that, The total number of sub - modules in the energy storage system is determined according to the number of redundant sub - modules, the number of initial sub - modules, and the number of the valve bridge arms.

5. A method for determining the number of sub-modules in an energy storage system, characterized in that, Including: Obtain the number of redundant sub - modules in the energy storage system, and obtain the number of initial sub - modules in the energy storage system; wherein, the number of the redundant sub - modules and / or the number of the initial sub - modules is related to the battery characteristics of the sub - modules in the energy storage system; Determine the total number of sub - modules in the energy storage system according to the number of the redundant sub - modules and the number of the initial sub - modules; Obtaining the number of redundant sub - modules in the energy storage system includes: Obtain the failure rate of the sub - modules in the energy storage system, and obtain the voltage drop rate of the sub - modules in the energy storage system; wherein, the voltage drop rate is related to the battery characteristics of the sub - modules in the energy storage system; Determine the number of the redundant sub - modules according to the number of the initial sub - modules, the failure rate of the sub - modules in the energy storage system, and the voltage drop rate of the sub - modules in the energy storage system.

6. The method according to claim 5, wherein Determining the number of the redundant sub - modules according to the number of the initial sub - modules, the failure rate of the sub - modules in the energy storage system, and the voltage drop rate of the sub - modules in the energy storage system includes: Determine the number of the first redundant sub - modules according to the number of the initial sub - modules and the voltage drop rate of the sub - modules in the energy storage system; Determine the number of the second redundant sub - modules according to the number of the initial sub - modules, the number of the first redundant sub - modules, and the failure rate of the sub - modules in the energy storage system, or determine the number of the second redundant sub - modules according to the number of the initial sub - modules and the failure rate of the sub - modules in the energy storage system. Determine the number of redundant sub-modules according to the number of the first redundant sub-modules and the number of the second redundant sub-modules.

7. The method according to claim 5, wherein The method further includes obtaining the system safety margin of the energy storage system; correspondingly, Determining the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of sub-modules in the energy storage system, and the voltage drop rate of sub-modules in the energy storage system includes: Determine the number of redundant sub-modules according to the number of initial sub-modules, the failure rate of sub-modules in the energy storage system, the voltage drop rate of sub-modules in the energy storage system, and the system safety margin.

8. The method according to claim 5, wherein Obtaining the voltage drop rate of sub-modules in the energy storage system includes: Obtain the internal resistance growth rate of the battery in the sub-module of the energy storage system when the battery is used until a specified period, the rated voltage of the battery, the rated current of the battery, and the initial internal resistance of the battery; Determine the voltage drop rate of the sub-module according to the internal resistance growth rate, the rated voltage, the rated current, and the initial internal resistance.

9. The method according to any one of claims 5-8, characterized in that, Obtaining the number of initial sub-modules in the energy storage system includes: Determine the number of initial sub-modules according to the total voltage of the energy storage system, the overvoltage level of the energy storage system, and the minimum voltage value of the sub-module in the energy storage system under different battery SOCs.

10. The method according to any one of claims 5 - 8, characterized in that, Determining the total number of sub-modules in the energy storage system according to the number of redundant sub-modules and the number of initial sub-modules includes: Determine the total number of sub-modules in the energy storage system according to the number of redundant sub-modules, the number of initial sub-modules, and the number of valve bridge arms in the energy storage system.

11. A method for determining the number of sub-modules in an energy storage system, characterized in that, Includes: Obtain the failure rate of sub-modules in the energy storage system, and obtain the voltage drop rate of sub-modules in the energy storage system, where the voltage drop rate is related to the battery characteristics of the sub-modules in the energy storage system; Determine the number of redundant sub-modules in the energy storage system according to the number of initial sub-modules required for the normal operation of the energy storage system, the failure rate of sub-modules in the energy storage system, and the voltage drop rate of sub-modules in the energy storage system.

12. A method for determining the number of sub-modules in an energy storage system, characterized in that, Includes: Obtain the number of initial sub-modules in the energy storage system; where the number of initial sub-modules is related to the battery characteristics of the sub-modules in the energy storage system; Determine the total number of sub-modules in the energy storage system according to the number of initial sub-modules and the redundancy; where the redundancy is related to the battery characteristics of the sub-modules in the energy storage system.

13. An electronic device, characterized in that, Includes: A memory for storing a program; A processor for calling the program stored in the memory to execute the method according to any one of claims 5-10, or execute the method according to claim 11, or execute the method according to claim 12.

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