Energy storage system and control method and apparatus therefor, device, medium, and program product

Abstract

The present application relates to an energy storage system and a control method and apparatus therefor, a device, a medium, and a program product. The energy storage system comprises: an energy storage apparatus used for connecting to an electric power system, the energy storage apparatus comprising a plurality of energy storage sub-modules, and the plurality of energy storage sub-modules at least comprising therein a first energy storage unit and a second energy storage unit. Charging and discharging rates of the first energy storage unit and the second energy storage unit are different. Each energy storage sub-module comprises a power unit, and one side of the power unit is electrically connected to the first energy storage unit and / or the second energy storage unit in a same energy storage sub-module. By means of the present application, the energy storage system can not only provide a large-current support capability for a short period, but also provide a long-term electric power and energy balancing service.

Description

Energy storage systems and their control methods, devices, equipment, media and program products Related applications

[0001] This application claims priority to Chinese patent application filed on November 1, 2024, with application number 2024115614245, entitled "Energy Storage System and Control Method, Apparatus, Equipment, Medium and Program Product Thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of power system technology, specifically to an energy storage system and its control method, device, equipment, medium, and program products. Background Technology

[0003] With the development of new energy technologies, the power system has a strong demand for energy storage systems that provide high voltage / large capacity, short-term high power inertia support / frequency regulation support, and long-term power balance support.

[0004] Currently, providing both short-term high-current support capabilities during transient periods and long-term power balance services is a major research direction for energy storage systems. Summary of the Invention

[0005] To address the aforementioned issues, this application provides an energy storage system and its control method, apparatus, equipment, medium, and program products, enabling the energy storage system to provide both short-term high-current support capability and long-term power balance service.

[0006] In a first aspect, this application provides an energy storage system, comprising: an energy storage device for connecting to a power system, the energy storage device including multiple energy storage sub-modules, the multiple energy storage sub-modules including at least a first energy storage unit and a second energy storage unit, wherein the first energy storage unit and the second energy storage unit have different charge and discharge rates; the energy storage sub-module includes a power unit, one side of the power unit being electrically connected to the first energy storage unit and / or the second energy storage unit belonging to the same energy storage sub-module.

[0007] In the technical solution of this application embodiment, the energy storage device of the energy storage system includes energy storage units with different charge and discharge rates. According to the different operating modes of the power system, energy storage units with different charge and discharge rates can be put into operation, thereby providing short-term high current support or long-term power balance services. This enables the energy storage system to provide multi-stage inertia, frequency regulation, and peak shaving services, making it more adaptable to the actual needs of the power system.

[0008] In some embodiments, multiple energy storage submodules are connected in series on the first main power transmission line of the energy storage device. The series connection of the energy storage submodules is achieved by connecting the output terminal of one power unit in one energy storage submodule to the input terminal of the power unit in the next energy storage submodule, forming a cascaded energy storage submodule. This allows for cascaded voltage boosting and direct connection to high-voltage buses, such as high-voltage AC grids, high-voltage DC grids, distribution networks, and microgrids. High voltage here refers to voltage levels above 10KV, providing support for large power grids. In the technical solution of this application embodiment, the energy storage device has a simple and easy-to-implement structure, low design cost, and low assembly cost. Furthermore, because different energy storage units have different charge and discharge rates, the energy storage system can provide both short-term high-current support and long-term power balance services.

[0009] In some embodiments, the multiple energy storage submodules include multiple first energy storage submodules and multiple second energy storage submodules; the multiple first energy storage submodules are connected in series on the first main power transmission line of the energy storage device; the multiple second energy storage submodules are connected in series on the second main power transmission line of the energy storage device; wherein the first main power transmission line and the second main power transmission line are connected in parallel. In the technical solution of this application embodiment, energy storage submodules are constructed from energy storage units with different charge and discharge rates, and then energy storage devices are constructed from energy storage submodules. In this way, the control device can activate energy storage units with different charge and discharge rates in the energy storage device according to inertia, frequency regulation, and peak regulation requirements, thereby better supporting the power system.

[0010] In some embodiments, the charge / discharge rates of the first energy storage unit and the second energy storage unit differ by more than 10 times. In the technical solution of this application embodiment, the difference in charge / discharge rates enables the energy storage system to provide both short-term high-current support and long-term power balance services.

[0011] In some embodiments, the ratio of the number of the first energy storage unit to the number of the second energy storage unit is 1:1 to 1:5. In the technical solutions of this application embodiment, more power, or higher voltage and greater current can be provided when providing long-term power balancing services.

[0012] In some embodiments, in the first energy storage unit and the second energy storage unit, the energy storage unit with a high charge / discharge rate includes high-rate cells or supercapacitors, while the energy storage unit with a low charge / discharge rate includes low-rate cells. The technical solution of this application embodiment provides both short-term high-current support and long-term power balance services, enabling the energy storage system to provide multi-stage inertia, frequency regulation, and peak-shaving services, thus better adapting to the actual needs of the power system.

[0013] In some embodiments, the energy storage system further includes a converter valve, through which the energy storage device is coupled to the power system; one side of the converter valve is used to connect to the power system, and the other side of the converter valve is connected to the energy storage device. In the technical solution of this application embodiment, AC / DC conversion is performed through the converter valve, and the energy storage device can be a DC-connected energy storage device. It can be constructed using a first energy storage unit and a second energy storage unit that provide DC power, which can reduce the design and implementation difficulty of the energy storage system, as well as the construction cost of the energy storage system.

[0014] In some embodiments, the converter valve includes a multilevel converter with a mixed configuration of full-bridge and half-bridge modules; the ratio of the number of full-bridge modules to the number of half-bridge modules is inversely correlated with the ratio of the DC voltage of the energy storage device to the AC voltage of the converter valve. In the technical solution of this application embodiment, the converter valve adopts a mixed configuration MMC topology, which can reduce the number of energy storage submodules configured in the energy storage device and meet the capacity requirements.

[0015] In some embodiments, the energy storage system further includes a control device coupled to the energy storage device. The control device is configured to, when determining that the energy storage device adopts a first power supply mode, control a first energy storage unit to connect to the power transmission path and control a second energy storage unit to disconnect from the power transmission path; and, when determining that the energy storage device adopts a second power supply mode, control a second energy storage unit to connect to the power transmission path and control a first energy storage unit to disconnect from the power transmission path. In the technical solution of this application embodiment, the control device can control the energy storage device in different ways depending on the power supply mode adopted by the energy storage device, thereby enabling the energy storage system to provide multi-stage inertia, frequency regulation, and peak shaving services, better adapting to the actual needs of the power system.

[0016] In some embodiments, the control device is further configured to control the converter valve to perform AC / DC conversion. In the technical solution of this application embodiment, the control device controls the AC / DC conversion, which can better supply power to the power system and improve the power supply performance of the energy storage system.

[0017] In some embodiments, the charge / discharge rate of the first energy storage unit is higher than that of the second energy storage unit. The first energy storage submodule includes a first energy storage unit, and the second energy storage submodule includes a second energy storage unit. The number of first energy storage submodules is positively correlated with short-term high-speed power demand; the number of second energy storage submodules is positively correlated with the power demand during peak shaving and backup power periods. In the technical solution of this application embodiment, the number of first energy storage submodules can meet short-term high-speed power demand, and the number of second energy storage submodules can meet the power demand during peak shaving and backup power periods. Therefore, the constructed energy storage device can provide better inertia, frequency regulation, and peak shaving support.

[0018] In some embodiments, the number of the first energy storage submodules is proportional to the short-term high-speed power demand and is adjusted according to the redundancy configuration and power over-sizing rate; the number of the second energy storage submodules is proportional to the power demand during peak-shaving backup power consumption and is adjusted according to the redundancy configuration and power over-sizing rate. In the technical solution of this application embodiment, by using redundancy configuration and calculating the power over-sizing rate, the problems of some energy storage submodules failing to function or insufficient power supply can be solved, while also meeting the power over-sizing rate requirement, thus providing the safety and reliability of the energy storage system.

[0019] In some embodiments, the capacity of the first energy storage submodule and the number of parallel-connected electrical cabinets within the module, as well as the capacity of the second energy storage submodule and the number of parallel-connected electrical cabinets within the module, are related to the submodule voltage level. The submodule voltage level is determined based on system parameters, which include one or more of the following: system voltage, capacity parameters, parameters of the first energy storage unit, parameters of the second energy storage unit, system inertia parameters, system frequency regulation ratio parameters, and system peak-shaving backup power duration parameters. In the technical solution of this application embodiment, the system parameters allow for the setting of a more reasonable capacity for the energy storage submodule and the number of parallel-connected electrical cabinets within the module, which can reduce the cost of the energy storage system and improve its support capabilities.

[0020] Secondly, this application also provides a control method for an energy storage system, the method comprising: when it is determined that the energy storage device in the energy storage system adopts a first power supply mode, controlling the first energy storage unit of the energy storage device to connect to the power transmission path, and controlling the second energy storage unit of the energy storage device to disconnect from the power transmission path; when it is determined that the energy storage device adopts a second power supply mode, controlling the second energy storage unit to connect to the power transmission path, and controlling the first energy storage unit to disconnect from the power transmission path.

[0021] In the technical solution of this application embodiment, energy storage units with different charging and discharging rates can be activated according to the inertia, frequency regulation, and peak regulation requirements characterized by the power system's operating mode, thereby improving the support capability of the energy storage system.

[0022] In some embodiments, the method further includes: determining that the energy storage device adopts a first power supply mode when the fluctuation of the system frequency is greater than the change threshold and a dispatch instruction from the power system is received, and it is determined that the inertial response and primary frequency regulation have not ended; and determining that the energy storage device adopts a second power supply mode when the fluctuation of the system frequency is greater than the change threshold and a dispatch instruction is received, and it is determined that the inertial response and primary frequency regulation have ended. In the technical solution of this application embodiment, determining the operating mode of the power system based on the power system disturbance situation can improve the support capability of the energy storage system and make the energy storage system more in line with actual power demand.

[0023] In some embodiments, the method further includes: when it is determined that the energy storage device adopts a first power supply mode, controlling the operating mode of the converter valve in the energy storage system to an inertia and primary frequency regulation mode; and when it is determined that the energy storage device adopts the first power supply mode, controlling the operating mode of the converter valve to a secondary frequency regulation mode. In the technical solution of this application embodiment, controlling the converter valve simultaneously according to the disturbance situation of the power system can enable the energy storage system to provide better support.

[0024] Thirdly, this application also provides a control device for an energy storage system, the device comprising:

[0025] The first control module is used to control the first energy storage unit of the energy storage device to connect to the power transmission path and control the second energy storage unit of the energy storage device to disconnect from the power transmission path when the energy storage device in the energy storage system adopts the first power supply mode.

[0026] The second control module is used to control the second energy storage unit to connect to the power transmission path and control the first energy storage unit to disconnect from the power transmission path when it is determined that the energy storage device adopts the second power supply mode.

[0027] Fourthly, this application also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method of any one of the second aspects.

[0028] Fifthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method of any one of the second aspects.

[0029] Sixthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the method of any one of the second aspects. Attached Figure Description

[0030] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the alternative embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0031] Figure 1a is a schematic diagram of the structure of an energy storage system according to an embodiment of this application;

[0032] Figure 1b is a schematic diagram of the structure of an energy storage system according to an embodiment of this application;

[0033] Figure 2a is a schematic diagram of the structure of an energy storage device according to an embodiment of this application;

[0034] Figure 2b is a second schematic diagram of the structure of an energy storage device according to an embodiment of this application;

[0035] Figure 2c is a third schematic diagram of the structure of an energy storage device according to an embodiment of this application;

[0036] Figure 2d is a fourth structural schematic diagram of an energy storage device according to an embodiment of this application;

[0037] Figure 3a is a fifth structural schematic diagram of an energy storage device according to an embodiment of this application;

[0038] Figure 3b is a schematic diagram of the structure of an energy storage device according to an embodiment of this application;

[0039] Figure 4 is a schematic diagram of the structure of an energy storage system according to another embodiment of this application;

[0040] Figure 5 is a second schematic diagram of the energy storage system according to another embodiment of this application;

[0041] Figure 6 is a schematic diagram of the structure of an energy storage system according to another embodiment of this application;

[0042] Figure 7 is a flowchart illustrating a control method for an energy storage system according to an embodiment of this application;

[0043] Figure 8 is a flowchart illustrating the steps for determining the power supply mode according to an embodiment of this application;

[0044] Figure 9 is a flowchart illustrating a control method for an energy storage system according to another embodiment of this application;

[0045] Figure 10 is a structural block diagram of a control device for an energy storage system according to an embodiment of this application;

[0046] Figure 11 is a second structural block diagram of the control device of an energy storage system according to an embodiment of this application;

[0047] Figure 12 is an internal structural diagram of an electronic device according to an embodiment of this application.

[0048] Explanation of reference numerals in the attached figures:

[0049] Energy storage system 10, energy storage device 11, converter valve 12, control device 13;

[0050] First energy storage unit B, second energy storage unit B';

[0051] First energy storage string 111, second energy storage string 112;

[0052] First energy storage submodule SM1, second energy storage submodule SM2;

[0053] First bypass switch K1, second bypass switch K2;

[0054] Circuit switch K3, pre-charge resistor R, pre-charge switch K4, inductor L;

[0055] Multilevel converter (MMC), full-bridge module 121, half-bridge module 122. Detailed Implementation

[0056] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0057] 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 this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0058] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0059] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0060] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0061] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0062] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0063] With the development of new energy technologies, the power system has a strong demand for energy storage systems that can provide high-voltage / large-capacity, short-term high-power inertia / frequency regulation support, and long-term power balance support. Currently, providing both short-term high-current support capability and long-term power balance service during transient periods is a major research direction for energy storage systems.

[0064] Research addressing the aforementioned needs revealed that energy storage units with high charge / discharge rates (charging and / or discharging rates) possess short-term, high-power charge / discharge characteristics, but their cost is high, typically requiring only small-capacity (low-power) cells to handle short-term charge / discharge conditions. Energy storage units with conventional charge / discharge rates have good long-term operation at rated current, but their short-term overcurrent capability is poor, failing to provide high-speed power support. Based on these findings, this application provides an energy storage system comprising an energy storage device, which includes a first energy storage unit and a second energy storage unit with different charge / discharge rates. In the technical solution of this application, the energy storage device includes energy storage units with different charge / discharge rates. Depending on the power system's operating mode, energy storage units with different charge / discharge rates can be connected to the power system to provide short-term high-current support or long-term power balancing services. This allows the energy storage system to provide multi-stage inertia, frequency regulation, and peak shaving services, better adapting to the actual needs of the power system.

[0065] According to some embodiments of this application, referring to FIG1a, an energy storage system is provided. The energy storage system 10 includes an energy storage device 11 for connecting to a power system. The energy storage device 11 includes a plurality of energy storage submodules SM. The plurality of energy storage submodules SM include at least a first energy storage unit B and a second energy storage unit B', wherein the first energy storage unit B and the second energy storage unit B' have different charge and discharge rates. The energy storage submodule SM includes a power unit G, one side of which is electrically connected to the first energy storage unit B and / or the second energy storage unit B' belonging to the same energy storage submodule SM.

[0066] In this embodiment, the energy storage system 10 includes an energy storage device 11. The energy storage device 11 includes multiple energy storage sub-modules SM, and the multiple energy storage sub-modules SM include at least a first energy storage unit B and a second energy storage unit B'. The first energy storage unit B and the second energy storage unit B' have different charge and discharge rates.

[0067] The energy storage submodule SM includes a power unit G, and there are several ways to connect the power unit G to the energy storage unit. As shown in Figure 1b, in the energy storage submodule SMMa, one side of the power unit G is connected to the first energy storage unit B belonging to the same energy storage submodule SM; in the energy storage submodule SMb, one side of the power unit G is connected to the second energy storage unit B' belonging to the same energy storage submodule SM; in the energy storage submodule SMc, the first energy storage unit B and the second energy storage unit B' belonging to the same energy storage submodule SM are first connected in series, and then connected to the power unit G; in the energy storage submodule SMd, the first energy storage unit B and the second energy storage unit B' belonging to the same energy storage submodule SM are connected in parallel, and then connected to the power unit G.

[0068] There are several ways to construct an energy storage device: 1) Constructed by multiple energy storage sub-modules SMa and multiple energy storage sub-modules SMb, as shown in Figure 1a; 2) Constructed by multiple energy storage sub-modules SMa and multiple energy storage sub-modules SMc; 3) Constructed by multiple energy storage sub-modules SMa and multiple energy storage sub-modules SMd; 4) Constructed by multiple energy storage sub-modules SMb and multiple energy storage sub-modules SMc; 5) Constructed by multiple energy storage sub-modules SMb and multiple energy storage sub-modules SMd; 6) Constructed by multiple energy storage sub-modules SMc and multiple energy storage sub-modules SMd; 7) Constructed by multiple energy storage sub-modules SMa, multiple energy storage sub-modules SMb, multiple energy storage sub-modules SMc and multiple energy storage sub-modules SMd, as shown in Figure 1b.

[0069] It should be noted that the construction method of energy storage devices is not limited to the above examples, and can be set according to the actual situation.

[0070] Depending on the power system's operating mode, energy storage devices need to provide short-term high-current support or long-term power balance services. In some embodiments, depending on the situation, the energy storage device connects the first energy storage unit B to the power system via power unit G and disconnects the second energy storage unit B' from the power system via power unit G; or, it connects the second energy storage unit B' to the power system via power unit G and disconnects the first energy storage unit B from the power system via power unit G.

[0071] In some embodiments, the first energy storage unit B and the second energy storage unit B' are connected in parallel, and then in parallel with the power unit G. The energy storage device, depending on the situation, controls the switch connected in series with the first energy storage unit B to turn on, connecting the first energy storage unit B to the power system; and controls the switch connected in series with the second energy storage unit B' to turn off, disconnecting the first energy storage unit B from the power system. Alternatively, the energy storage device controls the switch connected in series with the first energy storage unit B to turn off, disconnecting the first energy storage unit B from the power system; and controls the switch connected in series with the second energy storage unit B' to turn on, connecting the second energy storage unit B' to the power system.

[0072] In some embodiments, the first energy storage unit B and the second energy storage unit B' are connected in series and then in parallel with the power unit G. The energy storage device connects the first energy storage unit B to the power system and controls the switch connected in parallel with the second energy storage unit B' to conduct, bypassing the second energy storage unit B'; or, the energy storage device controls the switch connected in parallel with the first energy storage unit B to conduct, bypassing the first energy storage unit B, and connects the second energy storage unit B' to the power system.

[0073] It should be noted that the connection methods between the first energy storage unit B and the power system, and between the second energy storage unit B' and the power system, are not limited to the examples above and can be set according to the actual situation.

[0074] In the above embodiments, the energy storage system includes an energy storage device, which includes a first energy storage unit and a second energy storage unit with different charge and discharge rates, as well as a power unit. In the technical solution of this application embodiment, the energy storage device includes energy storage units with different charge and discharge rates. Depending on the different operating modes of the power system, energy storage units with different charge and discharge rates can be deployed to provide short-term high-current support or long-term power balance services. This allows the energy storage system to provide multi-stage inertia, frequency regulation, and peak-shaving services, better adapting to the actual needs of the power system.

[0075] According to some embodiments of this application, multiple energy storage submodules SM are connected in series on the first main power transmission line of the energy storage device 11.

[0076] In this embodiment of the application, there are multiple ways to connect the first energy storage unit B and the second energy storage unit B' in the energy storage device 11.

[0077] Referring to Figure 2a, one connection method may include: a power unit G comprising power devices S1 and S2, multiple first energy storage units B connected in series and then connected in parallel with the power unit G to form an energy storage submodule SMx, and multiple energy storage submodules SMx connected in series to form a first energy storage string 111. The power unit G comprises power devices S3 and S4, multiple second energy storage units B' connected in series and then connected in parallel with the power unit G to form an energy storage submodule SMy, and multiple energy storage submodules SMy connected in series to form a second energy storage string 112. The first energy storage string 111 and the second energy storage string 112 are connected in series on the first main power transmission line of the energy storage device 11.

[0078] Referring to Figure 2b, one connection method may include: a power unit G comprising power devices S1 and S2, multiple first energy storage units B connected in parallel, which are then connected in parallel with the power unit G to form an energy storage submodule SMx, and the multiple energy storage submodules SMx connected in series to form a first energy storage string 111. The power unit G comprises power devices S3 and S4, multiple second energy storage units B' connected in parallel, which are then connected in parallel with the power unit G to form an energy storage submodule SMy, and the multiple second energy storage submodules SMy connected in series to form a second energy storage string 112. The first energy storage string 111 and the second energy storage string 112 are connected in series on the first main power transmission line of the energy storage device 11.

[0079] Referring to Figure 2c, one connection method may include: power unit G including power devices S5 and S6, power unit G, first energy storage unit B and second energy storage unit B' connected in parallel, and energy storage submodule SMz formed based on this parallel structure. Multiple energy storage submodules SMz are connected in series on the first main power transmission line of energy storage device 11.

[0080] The energy storage submodule SMz also includes a first control switch K5 connected to the first energy storage unit B and a second control switch K6 connected to the second energy storage unit B'. When the first energy storage unit B needs to be used, the first control switch K5 in each energy storage submodule SMz is turned on, connecting the first energy storage unit B in each energy storage submodule SMz to the power transmission path, and the second control switch K6 in each energy storage submodule SMz is turned off, disconnecting the second energy storage unit B' in each hybrid energy storage submodule SMz from the power transmission path. When the second energy storage unit needs to be used, the second control switch K6 in each energy storage submodule SMz is turned on, connecting the second energy storage unit B' in each energy storage submodule SMz to the power transmission path, and the first control switch K5 in each energy storage submodule SMz is turned off, disconnecting the first energy storage unit B' in each energy storage submodule SMz from the power transmission path.

[0081] The aforementioned power unit G has two sides, one for connecting to the power system and the other for connecting to the energy storage unit. The aforementioned energy transmission path includes the path for transmitting electrical energy between the energy storage device and the power system.

[0082] It should be noted that the structure of the energy storage submodule SM is not limited to the example above and can be set according to the actual situation.

[0083] In some embodiments, each energy storage submodule SM further includes a filtering unit, which is connected in parallel with the power unit G. The filtering unit may include a filtering capacitor C, as shown in Figures 2a, 2b, and 2c.

[0084] Understandably, the filtering unit can filter out interference signals, improve the stability of the energy storage device, and thus reduce interference to the power system.

[0085] In some embodiments, referring to FIG2d, the energy storage submodule SMx includes a first bypass switch K1, and the energy storage submodule SMy includes a second bypass switch K2.

[0086] By controlling the first bypass switch K1 to turn off and controlling the power devices S1 and S2 in the energy storage submodule SMx, the energy storage submodule SMx can be connected to the power transmission path. By controlling the first bypass switch K1 to turn on and bypass the energy storage submodule SMx, the energy storage submodule SMx is disconnected from the power transmission path.

[0087] By controlling the second bypass switch K2 to turn off and controlling the power devices S3 and S4 in the energy storage submodule SMy, the energy storage submodule SMy can be connected to the power transmission path. By controlling the first bypass switch K1 to turn on and bypass the energy storage submodule SMy, the energy storage submodule SMy is disconnected from the power transmission path.

[0088] The energy storage device 11 can also be equipped with a circuit breaker K3 or an isolating switch, as well as a pre-charge resistor R, a pre-charge switch K4, and an inductor L. When high voltage is applied to the energy storage device 11, the circuit breaker K3 or the isolating switch can be turned on first, and the DC current flows into the energy storage sub-module through the pre-charge resistor R4. After a preset time, the pre-charge switch K4 is turned on to bypass the pre-charge resistor R.

[0089] Understandably, the energy storage submodule can be quickly switched on or off via a bypass switch, which is simple to control, easy to implement, and low in cost. The presence of a circuit breaker K3, an isolating switch, a pre-charge resistor R, and a pre-charge switch K4 protects the energy storage device 11, preventing excessive current in the power supply path from damaging the battery cells when high voltage is applied.

[0090] In the above embodiments, multiple energy storage submodules are connected in series on the first main power transmission line of the energy storage device. In the technical solution of this application embodiment, the energy storage device has a simple and easy-to-implement structure, low design cost, and low assembly cost. Furthermore, because different energy storage units have different charging and discharging rates, the energy storage system can provide both short-term high-current support and long-term power balance services.

[0091] In some embodiments, the plurality of energy storage submodules SM include a plurality of first energy storage submodules SM1 and a plurality of second energy storage submodules SM2; the plurality of first energy storage submodules SM1 are connected in series on the first main power transmission line of the energy storage device 11; the plurality of second energy storage submodules SM2 are connected in series on the second main power transmission line of the energy storage device 11; wherein the first main power transmission line and the second main power transmission line are connected in parallel.

[0092] In this embodiment of the application, there are multiple ways to connect the first energy storage unit B and the second energy storage unit B' in the energy storage device 11.

[0093] Referring to Figure 3a, one connection method may include: a power unit G comprising power devices S1 and S2; multiple first energy storage units B connected in series and then connected in parallel with the power unit G to form a first energy storage submodule SM1; the multiple first energy storage submodules SM1 are connected in series on the first main power transmission line of the energy storage device 11. The power unit G comprises power devices S3 and S4; multiple second energy storage units B' connected in series and then connected in parallel with the power unit G to form a second energy storage submodule SM2; the multiple second energy storage submodules SM2 are connected in series on the second main power transmission line of the energy storage device 11. The first and second main power transmission lines are connected in parallel.

[0094] Referring to Figure 3b, one connection method may include: a power unit G comprising power devices S1 and S2, multiple first energy storage units B connected in parallel, and then connected in parallel with the power unit G to form an energy storage submodule SMx, the multiple first energy storage submodules SMx being connected in series on the first main power transmission line of the energy storage device 11. The power unit G comprising power devices S3 and S4, multiple second energy storage units B' connected in parallel, and then connected in parallel with the power unit G to form an energy storage submodule SMy, the multiple energy storage submodules SMy being connected in series on the second main power transmission line of the energy storage device 11. The first and second main power transmission lines are connected in parallel.

[0095] It should be noted that the energy storage units in each energy storage submodule are not limited to multiple units; a single unit can be used. The power unit G has two sides: the first side connects to the power system, and the second side connects to the energy storage unit. Electrical energy can be transmitted from the power system to the first side of the power unit G, and then from the second side to the energy storage unit; alternatively, it can be transmitted from the energy storage unit to the second side of the power unit G, and then from the first side back to the power system. In other words, electrical energy can flow bidirectionally within the power unit G. The series connection between energy storage submodules is achieved through two electrical interfaces on the first side of the power unit G. Furthermore, the structure of the energy storage device is not limited to the above example and can be configured according to actual conditions.

[0096] In some embodiments, the first energy storage submodule SM1 and the second energy storage submodule SM2 further include a filtering unit, wherein the filtering unit may include a filtering capacitor C.

[0097] Understandably, the filtering unit can filter out interference signals, improve the stability of the energy storage device, and thus reduce interference to the power system.

[0098] In the above embodiments, the energy storage device includes a first energy storage string and a second energy storage string; the first energy storage string and the second energy storage string are connected in parallel or in series; the first energy storage string includes multiple first energy storage sub-modules connected in series, each first energy storage sub-module including a power unit and multiple first energy storage units connected in series and / or in parallel; the second energy storage string includes multiple second energy storage sub-modules connected in series, each second energy storage sub-module including a power unit and multiple second energy storage units connected in series and / or in parallel. In the technical solution of this application embodiment, energy storage sub-modules are constructed from energy storage units with different charge and discharge rates, and then energy storage devices are constructed from energy storage sub-modules. In this way, the control device can activate energy storage units with different charge and discharge rates in the energy storage device according to inertia, frequency regulation, and peak regulation requirements, thereby better supporting the power system.

[0099] In some embodiments, the difference in charge and discharge rates between the first energy storage unit B and the second energy storage unit B' exceeds 10 times.

[0100] Taking the charging and discharging rate of the first energy storage unit as greater than that of the second energy storage unit as an example, the charging and discharging rate of the first energy storage unit B is greater than or equal to 15C; the charging and discharging rate of the second energy storage unit B' is less than or equal to 1C, such as 0.25C, 0.5C, 1C, etc.

[0101] In the technical solution of this application embodiment, the difference in charging and discharging speed enables the energy storage system to provide both short-term high-current support and long-term power balance service.

[0102] In some embodiments, the ratio of the number of the first energy storage unit B to the number of the second energy storage unit B' is 1:1 to 1:5.

[0103] Taking the charging and discharging rate of the first energy storage unit B as greater than that of the second energy storage unit B' as an example, the number of second energy storage units B' can be the same as that of the first energy storage units B, or the number of second energy storage units B' can be much greater than that of the first energy storage units B. In this way, more electricity, or higher voltage and greater current can be provided when providing long-term power balance services.

[0104] In some embodiments, in the first energy storage unit B and the second energy storage unit B', the energy storage unit with a high charge / discharge rate includes a high-rate battery cell or a supercapacitor, and the energy storage unit with a low charge / discharge rate includes a low-rate battery cell.

[0105] In this embodiment, depending on the different operating modes of the power system, high-rate cells or supercapacitors are used to provide short-term high-current support, or conventional-rate cells are used to provide long-term power balance services, so that the energy storage system can provide multi-stage inertia, frequency regulation, and peak shaving services, which is more adaptable to the actual needs of the power system.

[0106] High-rate battery cells are characterized by excellent high-current discharge performance, strong discharge capability, high plateau, and good cycle life. Some high-rate battery cells can meet the discharge rate requirements of pulse 100C, continuous 60C, and fast charging capability up to 5C. Furthermore, high-rate battery cells also possess high energy density, employing a stacking process. Due to their low internal resistance, they are more conducive to high-rate charging and discharging, resulting in high-efficiency output performance; they also provide higher discharge rates and better temperature stability.

[0107] Supercapacitors can have very large current values ​​during charging and discharging, and the required charging and discharging time is correspondingly shorter, generally within tens of seconds to a few minutes, which is dozens of times faster than traditional electrochemical batteries.

[0108] In the above embodiments, in the first energy storage unit and the second energy storage unit, the energy storage unit with a high charge and discharge rate includes high-rate cells or supercapacitors, and the energy storage unit with a low charge and discharge rate includes low-rate cells. In this way, it can provide both short-term high-current support and long-term power balance services, enabling the energy storage system to provide multi-stage inertia, frequency regulation, and peak shaving services, and better adapt to the actual needs of the power system.

[0109] According to some embodiments of this application, referring to FIG4, the energy storage system 10 further includes a converter valve 12, one side of which is used to connect to the power system, and the other side of which is connected to the energy storage device 11.

[0110] In this embodiment, the AC side of the converter valve 12 can be connected to the power system (AC power system), and the DC side of the converter valve 12 is connected in parallel with the energy storage device 11.

[0111] The converter valve 12 can convert the alternating current (AC) of the AC power system into direct current (DC) and transmit the DC to the energy storage device 11 to charge the first energy storage unit B and / or the second energy storage unit B' in the energy storage device 11.

[0112] Alternatively, the converter valve 12 can convert the DC power of the energy storage device 11 into AC power and transmit the AC power to the AC power system. The AC power is then discharged through the first energy storage unit B and / or the second energy storage unit B' of the energy storage device 11 to supply power to the AC power system.

[0113] In the above embodiments, the energy storage system further includes a converter valve, through which the energy storage device is coupled to the power system; the control device is also used to control the converter valve to perform AC / DC conversion. In the technical solution of this application embodiment, AC / DC conversion is performed through the converter valve, and the energy storage device can be a DC direct-connected energy storage device, which can be constructed using a first energy storage unit and a second energy storage unit that provide DC power. This can reduce the design and implementation difficulty of the energy storage system, as well as the construction cost of the energy storage system.

[0114] According to some embodiments of this application, referring to FIG5, the converter valve 12 includes a multilevel converter (MMC) with a mixed configuration of full-bridge module 121 and half-bridge module 122; the ratio of the number of full-bridge module 121 to half-bridge module 122 is inversely correlated with the ratio of the DC voltage of the energy storage device 11 to the AC voltage of the converter valve 12.

[0115] In this embodiment, the converter valve 12 includes multiple multilevel converters (MMCs), which are a hybrid structure of full-bridge modules 121 and half-bridge modules 122. The full-bridge modules 121 can provide reverse voltage. By configuring the number of full-bridge modules 121, the voltage on the DC side of the converter valve 12 can be reduced. This reduces the voltage level of the energy storage device 11, thereby simplifying its design.

[0116] In practical applications, the switching ratio of the switching valve 12 can be determined based on the DC voltage of the energy storage device 11 and the AC voltage provided by the AC power system. Based on this switching ratio, the ratio of the number of full-bridge modules 121 and half-bridge modules 122 can be obtained.

[0117] For example, the DC voltage of the energy storage device 11 is ±10kV, and the AC voltage provided by the AC power system is ±30kV. Based on these two voltages, the conversion ratio can be determined to be 1:3. Based on this conversion ratio, the ratio of the number of full-bridge modules 121 to half-bridge modules 122 can be determined to be 3:1.

[0118] In some embodiments, considering the ability to isolate DC short-circuit faults, capacitors with sufficient voltage withstand capability are selected in the full-bridge module 121 and the half-bridge module 122.

[0119] In the above embodiments, the converter valve includes a multilevel converter with a mixed configuration of full-bridge and half-bridge modules; the ratio of the number of full-bridge modules to the number of half-bridge modules is inversely correlated with the ratio of the DC voltage of the energy storage device to the AC voltage of the converter valve. In the technical solution of this application embodiment, the converter valve adopts a mixed configuration MMC topology, which can reduce the number of energy storage sub-modules configured in the energy storage device and meet the capacity requirements.

[0120] According to some embodiments of this application, referring to FIG6, the energy storage system further includes a control device 13, which is coupled to the energy storage device 11. The control device 13 is configured to control the first energy storage unit B to connect to the power transmission path and control the second energy storage unit B' to disconnect from the power transmission path when it is determined that the energy storage device 11 adopts a first power supply mode; and to control the second energy storage unit B' to connect to the power transmission path and control the first energy storage unit B to disconnect from the power transmission path when it is determined that the energy storage device 11 adopts a second power supply mode.

[0121] In this embodiment, the control device 13 is communicatively connected to the energy storage device 11. Taking the energy storage device 11 providing short-term high-current support to the power system in a first power supply mode, and providing long-term power balance services to the power system in a second power supply mode, with the charging and discharging rate of the first energy storage unit B being greater than that of the second energy storage unit B', in the first power supply mode, the control device 13 controls the energy storage device 11 to connect the first energy storage unit B into the power transmission path and disconnect the second energy storage unit B' from the power transmission path. In the second power supply mode, the control device 13 controls the energy storage device 11 to connect the second energy storage unit B' into the power transmission path and disconnect the first energy storage unit B' from the power transmission path.

[0122] In the above embodiments, the energy storage system further includes a control device. When the energy storage device is determined to use a first power supply mode, the control device controls the first energy storage unit to connect to the power transmission path and controls the second energy storage unit to disconnect from the power transmission path; and when the energy storage device is determined to use a second power supply mode, the control device controls the second energy storage unit to connect to the power transmission path and controls the first energy storage unit to disconnect from the power transmission path. In the technical solution of this application embodiment, the control device can control the energy storage device in different ways depending on the power supply mode adopted by the energy storage device, thereby enabling the energy storage system to provide multi-stage inertia, frequency regulation, and peak shaving services, better adapting to the actual needs of the power system.

[0123] According to some embodiments of this application, the control device 13 is also used to control the converter valve 12 to perform AC / DC conversion.

[0124] In this embodiment, the control device 13 is coupled to the converter valve 12. Under the control of the control device 13, the converter valve 12 converts the AC power from the AC power system into DC power and transmits the DC power to the energy storage device 11 to charge the first energy storage unit B and / or the second energy storage unit B' in the energy storage device 11.

[0125] Alternatively, under the control of the control device 13, the converter valve 12 converts the DC power of the energy storage device 11 into AC power and transmits the AC power to the AC power system. The AC power is then discharged through the first energy storage unit B and / or the second energy storage unit B' of the energy storage device 11 to supply power to the AC power system.

[0126] It should be noted that the control devices for the energy storage device and the converter valve can be integrated into one unit, or separate control devices can be set up for the energy storage device and the converter valve. When separate control devices are set up for the energy storage device and the converter valve, a coordination controller can be set up to connect the control devices of the energy storage device and the converter valve.

[0127] In the above embodiments, the control device controls the converter valve to perform AC / DC conversion. In the technical solution of this application embodiment, the control device controls the AC / DC conversion, which can better supply power to the power system and improve the power supply performance of the energy storage system.

[0128] According to some embodiments of this application, the charging and discharging rate of the first energy storage unit B is higher than that of the second energy storage unit B', the number of the first energy storage submodule SM1 is positively correlated with the short-term high-speed power demand, and the number of the second energy storage submodule SM2 is positively correlated with the power demand during peak shaving and backup power periods.

[0129] In this embodiment of the application, before constructing the energy storage device 11, the number of first energy storage submodules SM1 can be calculated based on the short-term high-speed power demand of the power system and the capacity of a single first energy storage submodule SM1. For example, if the short-term high-speed power demand is Q1 and the capacity of a single first energy storage submodule SM1 is Q2, then the number of first energy storage submodules SM1 is m = Q1 / Q2.

[0130] Similarly, the number of second energy storage submodules SM2 can be calculated based on the power demand during peak shaving and backup power generation in the power system, and the capacity of a single second energy storage submodule SM2. For example, if the power demand during peak shaving and backup power generation is Q3, and the capacity of a single second energy storage submodule SM2 is Q4, then the number of second energy storage submodules SM2 is n = Q3 / Q4.

[0131] Subsequently, based on the number of the first energy storage submodule SM1 and the number of the second energy storage submodule SM2, an energy storage device 11 that meets the short-term high-speed power demand and the long-term power demand for peak shaving and backup power can be constructed.

[0132] In the above embodiments, the charging and discharging rate of the first energy storage unit is higher than that of the second energy storage unit. The number of the first energy storage sub-modules is positively correlated with the short-term high-speed power demand; the number of the second energy storage sub-modules is positively correlated with the power demand during peak shaving and backup power periods. In the technical solution of this application embodiment, the number of the first energy storage sub-modules can meet the short-term high-speed power demand, and the number of the second energy storage sub-modules can meet the power demand during peak shaving and backup power periods. Therefore, the constructed energy storage device can provide better inertia, frequency regulation, and peak shaving support.

[0133] According to some embodiments of this application, the number of the first energy storage submodule SM1 is proportional to the short-term high-speed power demand and is adjusted according to the redundancy configuration and power over-provision rate; the number of the second energy storage submodule SM2 is proportional to the power demand during peak shaving and backup power duration and is adjusted according to the redundancy configuration and power over-provision rate.

[0134] In practical applications, one or more of the following problems may arise: energy storage submodules may fail and become unusable; all first energy storage submodules SM1 may be operational but still insufficient to meet short-term high-speed power demands; and all second energy storage submodules SM2 may be operational but still insufficient to meet peak-shaving backup power demands. Given this situation, redundant configuration needs to be considered, i.e., configuring an additional number of first energy storage submodules SM1 and second energy storage submodules SM2. With redundant energy storage submodule configuration, the power over-provision rate also needs to be considered to prevent the power connected to the power supply path from exceeding the power demand, thus affecting the safety and reliability of the energy storage system 10.

[0135] Based on the above considerations, after determining the number of the first energy storage submodule SM1 according to the short-term high-speed power demand and the number of the second energy storage submodule SM2 according to the peak-shaving backup power demand, the above quantities can be corrected according to the redundancy configuration.

[0136] For example, if the redundancy configuration is p%, the number of the first energy storage submodule SM1 is m, and the corrected number of the first energy storage submodule SM1 is M = m + m * p%, and the number of the second energy storage submodule SM2 is n, and the corrected number of the second energy storage submodule SM2 is N = n + n * p%.

[0137] Based on the revised number of first energy storage submodules SM1, the capacity of a single first energy storage submodule SM1, and the short-term high-speed power demand, calculate the power over-sizing rate of the first energy storage submodule SM1. Based on the revised number of second energy storage submodules SM2, the capacity of a single second energy storage submodule SM2, and the power demand for peak shaving and backup power, calculate the power over-sizing rate of the second energy storage submodule SM2.

[0138] If the over-allocation rate of the first energy storage submodule SM1 and the over-allocation rate of the second energy storage submodule SM2 both meet the preset over-allocation rate requirements, then the energy storage device 11 is constructed based on the corrected number of the first energy storage submodule SM1 and the corrected number of the second energy storage submodule SM2.

[0139] If the overcapacity rate of the first energy storage submodule SM1 and / or the overcapacity rate of the second energy storage submodule SM2 does not meet the preset overcapacity rate requirement, the number of energy storage submodules that do not meet the requirement will be adjusted again, or the number of battery cells and the number of electrical cabinets connected to the energy storage submodules that do not meet the requirement will be adjusted. Then, the energy storage device 11 is constructed based on the finally adjusted number of the first energy storage submodule SM1 and the second energy storage submodule SM2.

[0140] In the above embodiments, the number of the first energy storage submodules is proportional to the short-term high-speed power demand and is adjusted according to the redundancy configuration and power over-sizing rate; the number of the second energy storage submodules is proportional to the power demand during peak-shaving backup power consumption and is adjusted according to the redundancy configuration and power over-sizing rate. In the technical solution of this application embodiment, by using redundancy configuration and calculating the power over-sizing rate, the problems of some energy storage submodules failing to function or insufficient power supply can be solved, while also meeting the power over-sizing rate requirements, thus improving the safety and reliability of the energy storage system.

[0141] According to some embodiments of this application, the capacity of the first energy storage submodule SM1 and the number of parallel electrical cabinets within the module, as well as the capacity of the second energy storage submodule SM2 and the number of parallel electrical cabinets within the module, are related to the voltage level of the submodule. The voltage level of the submodule is determined based on system parameters, which include one or more of the following: system voltage, capacity parameters, parameters of the first energy storage unit, parameters of the second energy storage unit, system inertia parameters, system frequency regulation ratio parameters, and system peak shaving backup power duration parameters.

[0142] In this embodiment, before constructing the energy storage system 10, one or more system parameters can be determined based on the design requirements of the energy storage system 10, including system voltage, capacity parameters, first energy storage unit parameters, second energy storage unit parameters, system inertia parameters, system frequency regulation ratio parameters, and system peak shaving backup power duration parameters. Then, based on these system parameters, the submodule voltage level of each energy storage submodule is calculated, i.e., the highest voltage that each energy storage submodule needs to withstand.

[0143] The capacity of a single first energy storage submodule SM1 is calculated based on the submodule voltage level of a single energy storage submodule, and the number of parallel-connected electrical cabinets within the module is calculated based on the capacity of a single electrical cabinet and the capacity of a single first energy storage submodule SM1.

[0144] Similarly, the capacity of a single second energy storage submodule SM2 is calculated based on the submodule voltage level of a single energy storage submodule, and the number of parallel-connected electrical cabinets within the module is calculated based on the capacity of a single electrical cabinet and the capacity of a single second energy storage submodule SM2.

[0145] In the above embodiments, the capacity of the first energy storage submodule and the number of parallel electrical cabinets within the module, as well as the capacity of the second energy storage submodule and the number of parallel electrical cabinets within the module, are related to the voltage level of the submodule. In the technical solution of this application embodiment, system parameters can be used to set a more reasonable capacity for the energy storage submodule and the number of parallel electrical cabinets within the module, which can reduce the cost of the energy storage system and improve its support capabilities.

[0146] According to some embodiments of this application, referring to FIG7, a control method for an energy storage system is provided. Taking the application of this method to the control device of the energy storage system in the above embodiments as an example, it may include the following steps:

[0147] Step 201: When it is determined that the energy storage device in the energy storage system adopts the first power supply mode, control the first energy storage unit of the energy storage device to connect to the power transmission path, and control the second energy storage unit of the energy storage device to disconnect from the power transmission path.

[0148] The control device can directly determine the power system's operating mode based on the system frequency, or obtain the power system's system frequency and system dispatch instructions, and determine the power system's operating mode based on the system frequency and system dispatch instructions. Then, it determines the power supply mode to be used by the energy storage device based on the power system's operating mode.

[0149] For example, a pre-set correspondence can be established in the control device. After acquiring the system frequency and system dispatch command, the operating mode of the power system can be determined based on the correspondence. Then, based on the correspondence between the operating mode and the power supply mode, the power supply mode adopted by the energy storage device can be determined. For example, when the system frequency is f1 and the system dispatch command is D1, the operating mode of the power system is determined to be the first operating mode E1, and the energy storage device adopts the first power supply mode F1; when the system frequency is f2 and the system dispatch command is D2, the operating mode of the power system is determined to be the second operating mode E2, and the energy storage device adopts the second power supply mode F2.

[0150] It should be noted that the above correspondence can be determined statistically based on historical data, calculated using a model, or determined through system simulation.

[0151] Taking the first power supply mode as an example, which corresponds to the energy storage system needing to provide short-term high current support, and the charging and discharging rate of the first energy storage unit is greater than that of the second energy storage unit, if it is determined that the energy storage device adopts the first power supply mode, the control device controls the energy storage device to connect the first energy storage unit into the power transmission path and disconnect the second energy storage unit from the power transmission path.

[0152] Step 202: When it is determined that the energy storage device adopts the second power supply mode, control the second energy storage unit to connect to the power transmission path and control the first energy storage unit to disconnect from the power transmission path.

[0153] Taking the second power supply mode as an example, and the energy storage system needs to provide long-term power balance services, with the first energy storage unit having a higher charging and discharging rate than the second energy storage unit, if it is determined that the energy storage device adopts the second power supply mode, the control device controls the energy storage device to connect the second energy storage unit into the power transmission path and disconnect the first energy storage unit from the power transmission path.

[0154] It should be noted that the order of steps 201 and 202 above is not limited to that shown in the flowchart.

[0155] In the above embodiments, when it is determined that the energy storage device in the energy storage system adopts a first power supply mode, the first energy storage unit of the energy storage device is controlled to connect to the power transmission path, and the second energy storage unit of the energy storage device is controlled to disconnect from the power transmission path; when it is determined that the energy storage device adopts a second power supply mode, the second energy storage unit is controlled to connect to the power transmission path, and the first energy storage unit is controlled to disconnect from the power transmission path. In the technical solution of this application embodiment, energy storage units with different charging and discharging rates can be activated according to the inertia, frequency regulation, and peak regulation requirements characterized by the power system's operating mode, thereby improving the support capability of the energy storage system.

[0156] According to some embodiments of this application, referring to FIG8, the following steps may also be included:

[0157] Step 301: When the fluctuation of the system frequency of the power system is greater than the change threshold and the dispatch instruction of the power system is received, and the inertial response and primary frequency regulation have not ended, the energy storage device is determined to adopt the first power supply mode.

[0158] The control device acquires the system frequency from the frequency detection equipment and calculates the fluctuation of the system frequency within a preset time period. If the fluctuation of the system frequency exceeds a change threshold, it indicates that the power system is experiencing significant fluctuations. In this case, if a dispatch command is also received, the control device determines whether the inertial response and primary frequency regulation have ended within a preset time scale. Optionally, the preset time scale is 30 seconds.

[0159] If the inertial response and primary frequency regulation have not ended, it indicates that the energy storage system needs to provide short-term high-current support. Therefore, the power system is determined to be in the first operating mode, and the energy storage device adopts the first power supply mode. Based on the short-term support control, the energy storage device engages the first energy storage unit and disconnects the second energy storage unit, while continuously acquiring the system frequency.

[0160] If, after providing short-term high-current support, the fluctuation in system frequency is less than the change threshold, it indicates that the power system fluctuation is small, and the system returns to a stable state. If the fluctuation in system frequency is still greater than the change threshold, then it is necessary to determine whether the inertial response and primary frequency regulation have ended.

[0161] Step 302: When the fluctuation of the system frequency is greater than the change threshold and a scheduling instruction is received, and the inertial response and the first frequency regulation are determined to be completed, the energy storage device is determined to adopt the second power supply mode.

[0162] The control device obtains the system frequency from the frequency detection equipment and calculates the fluctuation of the system frequency within a preset time period. If the fluctuation of the system frequency is greater than the change threshold, it indicates that the power system is fluctuating significantly. In this case, if a dispatch command is also received, it determines whether the inertial response and primary frequency regulation have ended within the preset time scale.

[0163] Given the determined inertial response and the end of primary frequency regulation, indicating a need for long-term power balance services from the energy storage system, the power system is determined to be in the second operating mode, and the energy storage device adopts the second power supply mode. Based on the long-term support control, the energy storage device engages the second energy storage unit and disconnects the first energy storage unit.

[0164] It should be noted that the order of steps 301 and 302 above is not limited to that shown in the flowchart.

[0165] In some embodiments, the control method of the converter valve may also include the following:

[0166] 1) When the energy storage device adopts the first power supply mode, the operating mode of the converter valve in the energy storage system is the inertia and primary frequency regulation mode.

[0167] 2) When it is determined that the energy storage device adopts the second power supply mode, the operating mode of the control converter valve is the secondary frequency regulation mode.

[0168] When the energy storage device adopts the first power supply mode, a constant DC voltage is used to control the energy storage device, and the operating mode of the converter valve in the energy storage system is controlled to inertia and primary frequency regulation mode. When the energy storage device adopts the second power supply mode, a constant DC voltage is used to control the energy storage device, and the operating mode of the converter valve in the energy storage system is controlled to secondary frequency regulation mode.

[0169] Understandably, controlling the converter valves simultaneously based on the disturbances in the power system can provide better support for the energy storage system.

[0170] In the above embodiments, when the fluctuation of the power system frequency exceeds the change threshold and a dispatch instruction from the power system is received, and it is determined that the inertial response and primary frequency regulation have not ended, the energy storage device is determined to adopt a first power supply mode. When the fluctuation of the system frequency exceeds the change threshold and a dispatch instruction is received, and it is determined that the inertial response and primary frequency regulation have ended, the energy storage device is determined to adopt a second power supply mode. In the technical solution of this application embodiment, determining the corresponding control method according to the power system disturbance situation can improve the support capability of the energy storage system and make the energy storage system more in line with actual power demand.

[0171] According to some embodiments of this application, a control method for an energy storage system is provided. Taking the application of this method to the energy storage system in the above embodiments as an example, and referring to FIG9, it may include the following steps:

[0172] Step 1: Obtain the system frequency and dispatch instructions for the power supply.

[0173] Step 2: When the fluctuation of the system frequency is greater than the change threshold and the dispatch instruction of the power system is received, and the inertial response and primary frequency regulation have not ended, the energy storage device is determined to adopt the first power supply mode.

[0174] Step 3: Control the first energy storage unit of the energy storage device to connect to the energy transmission path, and control the second energy storage unit of the energy storage device to disconnect from the energy transmission path. Control the working mode of the converter valve in the energy storage system to inertia and primary frequency regulation mode.

[0175] Step 4: When the fluctuation of the system frequency is greater than the change threshold and a scheduling instruction is received, and the inertial response and the first frequency regulation are completed, the energy storage device is determined to adopt the second power supply mode.

[0176] Step 5: Control the second energy storage unit to connect to the power transmission path, control the first energy storage unit to disconnect from the power transmission path, and control the working mode of the converter valve to the secondary frequency regulation mode.

[0177] In the above embodiments, when a power system disturbance occurs, the first energy storage unit can be activated first, followed by the second energy storage unit. This allows the first energy storage unit to provide high-power support while also ensuring long-term power balance support.

[0178] It should be understood that although the steps in the flowchart above are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowchart above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps.

[0179] Based on the same inventive concept, this application also provides a control device for an energy storage system to implement the control method of the energy storage system described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of the one or more control device embodiments of the energy storage system provided below can be found in the limitations of the control method of the energy storage system above, and will not be repeated here.

[0180] According to some embodiments of this application, referring to FIG10, a control device for an energy storage system is provided, the device comprising:

[0181] The first control module 401 is used to control the first energy storage unit of the energy storage device to connect to the power transmission path and control the second energy storage unit of the energy storage device to disconnect from the power transmission path when it is determined that the energy storage device in the energy storage system adopts the first power supply mode.

[0182] The second control module 402 is used to control the second energy storage unit to connect to the power transmission path and control the first energy storage unit to disconnect from the power transmission path when it is determined that the energy storage device adopts the second power supply mode.

[0183] In some embodiments, referring to FIG11, the device further includes:

[0184] The first mode determination module 403 is used to determine that the energy storage device adopts the first power supply mode when the fluctuation of the system frequency is greater than the change threshold and the dispatching instruction of the power system is received, and the inertial response and primary frequency regulation have not ended.

[0185] The second mode determination module 404 is used to determine that the energy storage device adopts the second power supply mode when the fluctuation of the system frequency is greater than the change threshold and a scheduling instruction is received, and the inertial response and the first frequency regulation are completed.

[0186] In some embodiments, the first control module 401 is further configured to determine that the energy storage device adopts a first power supply mode and control the working mode of the converter valve in the energy storage system to inertia and primary frequency regulation mode.

[0187] The second control module 402 is also used to determine that the energy storage device adopts the first power supply mode and to control the working mode of the converter valve to be the secondary frequency regulation mode.

[0188] The various modules in the control device of the aforementioned energy storage system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of the electronic device in hardware form or independent of it, or stored in the memory of the electronic device in software form, so that the processor can call and execute the operations corresponding to each module.

[0189] According to some embodiments of this application, an electronic device is provided, which can be a control device in an energy storage system. Its internal structure is shown in Figure 12. The electronic device includes a processor, a memory, an input / output interface, a communication interface, a display module, and an input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display module, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a control method for an energy storage system. The display module is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the electronic device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the electronic device, or external keyboards, touchpads, or mice, etc.

[0190] Those skilled in the art will understand that the structure shown in Figure 12 is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0191] According to some embodiments of this application, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory including instructions that can be executed by a processor of an electronic device to perform the above-described method. For example, the non-transitory computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc.

[0192] According to some embodiments of this application, a computer program product is also provided, which, when executed by a processor, can implement the above-described methods. The computer program product includes one or more computer instructions. When these computer instructions are loaded and executed on a computer, some or all of the above-described methods can be implemented, wholly or partially, according to the processes or functions described in the embodiments of this application.

[0193] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0194] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0195] The embodiments described above merely illustrate several implementation methods of this application to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. An energy storage system, wherein, The energy storage system includes: An energy storage device for connecting to a power system, the energy storage device comprising multiple energy storage sub-modules, the multiple energy storage sub-modules including at least a first energy storage unit and a second energy storage unit, wherein the first energy storage unit and the second energy storage unit have different charge and discharge rates; The energy storage submodule includes a power unit, one side of which is electrically connected to a first energy storage unit and / or a second energy storage unit belonging to the same energy storage submodule.

2. The energy storage system according to claim 1, wherein, Multiple energy storage submodules are connected in series on the first main power transmission line of the energy storage device.

3. The energy storage system according to claim 1, wherein, The plurality of energy storage submodules include a plurality of first energy storage submodules and a plurality of second energy storage submodules; Multiple first energy storage sub-modules are connected in series on the first main power transmission line of the energy storage device; Multiple second energy storage submodules are connected in series on the second main power transmission line of the energy storage device; The first main power transmission line and the second main power transmission line are connected in parallel.

4. The energy storage system according to any one of claims 1 to 3, wherein, The charging and discharging rates of the first energy storage unit and the second energy storage unit differ by more than 10 times.

5. The energy storage system according to any one of claims 1 to 4, wherein, The ratio of the number of the first energy storage unit to the number of the second energy storage unit is 1:1 to 1:

5.

6. The energy storage system according to any one of claims 1 to 5, wherein, In the first energy storage unit and the second energy storage unit, the energy storage unit with a high charge and discharge rate includes high-rate cells or supercapacitors, and the energy storage unit with a low charge and discharge rate includes low-rate cells.

7. The energy storage system according to any one of claims 1 to 6, wherein, The energy storage system also includes a converter valve, one side of which is used to connect to the power system, and the other side of which is connected to the energy storage device.

8. The energy storage system according to claim 7, wherein, The converter valve includes a multilevel converter with a mixed configuration of full-bridge and half-bridge modules; the ratio of the number of full-bridge modules to the number of half-bridge modules is inversely correlated with the ratio of the DC voltage of the energy storage device to the AC voltage of the converter valve.

9. The energy storage system according to claim 7, wherein, The energy storage system also includes a control device, which is coupled to the energy storage device; The control device is used to control the first energy storage unit to connect to the power transmission path and control the second energy storage unit to disconnect from the power transmission path when it is determined that the energy storage device adopts the first power supply mode. And when it is determined that the energy storage device adopts the second power supply mode, control the second energy storage unit to connect to the power transmission path, and control the first energy storage unit to disconnect from the power transmission path.

10. The energy storage system according to claim 9, wherein, The control device is also used to control the converter valve to perform AC / DC conversion.

11. The energy storage system according to claim 1, wherein, The charging and discharging rate of the first energy storage unit is higher than that of the second energy storage unit. The first energy storage submodule includes the first energy storage unit, and the second energy storage submodule includes the second energy storage unit. The number of the first energy storage submodules is positively correlated with the short-term high-rate power demand; the number of the second energy storage submodules is positively correlated with the power demand for peak shaving and backup power duration.

12. The energy storage system according to claim 11, wherein, The number of the first energy storage submodules is proportional to the short-term high-speed power demand and is adjusted according to the redundancy configuration and power over-provision rate; the number of the second energy storage submodules is proportional to the peak-shaving backup power duration power demand and is adjusted according to the redundancy configuration and power over-provision rate.

13. The energy storage system according to claim 11, wherein, The capacity of the first energy storage submodule and the number of parallel electrical cabinets within the module, as well as the capacity of the second energy storage submodule and the number of parallel electrical cabinets within the module, are related to the voltage level of the submodule. The voltage level of the submodule is related to the system parameters, which include one or more of the following: system voltage, capacity parameters, first energy storage unit parameters, second energy storage unit parameters, system inertia parameters, system frequency regulation ratio parameters, and system peak shaving backup power duration parameters.

14. A control method for an energy storage system, wherein, The method includes: When it is determined that the energy storage device in the energy storage system adopts the first power supply mode, the first energy storage unit of the energy storage device is controlled to connect to the power transmission path, and the second energy storage unit of the energy storage device is controlled to disconnect from the power transmission path. When it is determined that the energy storage device adopts the second power supply mode, the second energy storage unit is controlled to connect to the power transmission path, and the first energy storage unit is controlled to disconnect from the power transmission path.

15. The method according to claim 14, wherein, The method further includes: If the fluctuation of the system frequency of the power system is greater than the change threshold, and the dispatch instruction of the power system is received, and it is determined that the inertial response and primary frequency regulation have not ended, the energy storage device is determined to adopt the first power supply mode. If the fluctuation of the system frequency is greater than the change threshold, and the scheduling instruction is received, and the inertial response and the first frequency regulation are determined to be completed, the energy storage device is determined to adopt the second power supply mode.

16. The method of claim 14, wherein, The method further includes: When it is determined that the energy storage device adopts the first power supply mode, the working mode of the converter valve in the energy storage system is controlled to be inertia and primary frequency regulation mode. When it is determined that the energy storage device adopts the second power supply mode, the operating mode of the converter valve is controlled to be the secondary frequency regulation mode.

17. A control device for an energy storage system, wherein, The device includes: The first control module is used to control the first energy storage unit of the energy storage device to connect to the power transmission path and control the second energy storage unit of the energy storage device to disconnect from the power transmission path when it is determined that the energy storage device in the energy storage system adopts the first power supply mode. The second control module is used to control the second energy storage unit to connect to the energy transmission path and control the first energy storage unit to disconnect from the energy transmission path when it is determined that the energy storage device adopts the second power supply mode.

18. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein, When the processor executes the computer program, it implements the method of any one of claims 14 to 16.

19. A computer-readable storage medium having a computer program stored thereon, wherein, When the computer program is executed by a processor, it implements the method of any one of claims 14 to 16.

20. A computer program product comprising a computer program, wherein, When the computer program is executed by a processor, it implements the method of any one of claims 14 to 16.

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