Control method of energy storage system and energy storage system

Abstract

The invention relates to the technical field of energy storage, and discloses a control method of an energy storage system and the energy storage system.The control method of the energy storage system comprises the steps that a control module of the ith level obtains first power; summarizing the first power to obtain second power of the grid connection point of the ith level; adjusting the second power according to a preset rule to obtain the adjusted second power; under the condition that i is smaller than N, the control module of the ith level reports the adjusted second power to the control module of the (i + 1) th level; acquiring first target power of the grid connection point of the ith level; determining second target power of the grid connection point or the energy storage cabinet of the (i-1) th level according to the adjusted second power and the first target power, and issuing the second target power to the control module or the energy storage cabinet of the (i-1) th level; therefore, the hardware cost of the energy storage system is reduced, the cooperation efficiency of the energy storage system is improved, and the power control adaptability is high.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a control method for an energy storage system and an energy storage system. Background Art

[0002] Currently, traditional energy storage systems use a configuration method with multiple local EMS hardware. In this configuration, each energy storage cabinet is configured as a slave cabinet and is connected to the master cabinet via a communication line to form a master-slave architecture. Each master cabinet and slave cabinet is equipped with an independent EMS.

[0003] However, current energy storage systems have problems such as high hardware cost, low coordination efficiency, and poor power control adaptability. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a control method and an energy storage system, thereby reducing the hardware cost of the energy storage system, improving the coordination efficiency of the energy storage system, and having high power control adaptability.

[0005] In order to solve the above technical problems, an embodiment of the present application provides a control method for an energy storage system, which is applied to an energy management system of an energy storage system, wherein the energy management system is connected to at least one energy storage cabinet through a switch; the energy storage system includes N levels of grid connection points, where N is an integer greater than 0; the grid connection point of the first level is connected to the energy storage cabinet, and the energy management system includes N levels of control modules, the grid connection point of the i-th level corresponds to the control module of the i-th level, 0<i≤N, and i is an integer; the control method of the energy storage system includes: the control module of the i-th level obtains a first power; when i is greater than 1, the first power is the first power reported by the control module of the i-1-th level. The power of the grid connection point at the i-1 level, when i is equal to 1, the first power is the power reported by the energy storage cabinet; the first power is aggregated to obtain the second power of the grid connection point at the i-th level; the second power is adjusted according to the preset rule to obtain the adjusted second power; when i is less than N, the control module at the i-th level reports the adjusted second power to the control module at the i+1-th level; the first target power of the grid connection point at the i-th level is obtained; the second target power of the grid connection point or the energy storage cabinet at the i-1-th level is determined based on the adjusted second power and the first target power, and is sent to the control module or the energy storage cabinet at the i-1-th level.

[0006] An embodiment of the present application further provides an energy storage system, comprising: an energy management system, a switch, and an energy storage cabinet; the energy management system is connected to at least one of the energy storage cabinets via the switch; the energy storage system comprises N levels of grid connection points, the grid connection point of the first level is connected to the energy storage cabinet, the energy management system comprises N levels of control modules, the grid connection point of the i-th level corresponds to the control module of the i-th level, 0<i≤N, and i is an integer; the control module of the i-th level is configured to obtain a first power; when i is greater than 1, the first power is the i-th power reported by the control module of the i-1-th level. -1 level said grid connection point, when i is equal to 1, the first power is the power reported by the energy storage cabinet; summarizing the first power to obtain the second power of the grid connection point of the i-th level; adjusting the second power according to a preset rule to obtain the adjusted second power; reporting the second power to the control module of the i+1th level; obtaining the first target power of the grid connection point of the i-th level; determining the second target power of the grid connection point or the energy storage cabinet of the i-1th level according to the adjusted second power and the first target power, and sending it to the control module or the energy storage cabinet of the i-1th level.

[0007] In some embodiments, adjusting the second power according to a preset rule to obtain the adjusted second power includes: the control module at the i-th level obtaining the charge and discharge status of the energy storage system based on the second power before adjustment; executing charging protection control when the energy storage system is in a charging state; and executing discharging protection control when the energy storage system is in a discharging state.

[0008] In some embodiments, the charging protection control is: determine whether the sum of the second power and the first load power is greater than the target demand power; if so, adjust the second power to the difference between the first load power and the target demand power; if not, maintain the current second power; the discharging protection control is: determine whether the second power is greater than the difference between the second load power and the minimum off-grid power; if so, adjust the second power to the difference between the second load power and the minimum off-grid power; if not, maintain the current second power.

[0009] In some embodiments, the first load power is the sum of the demand powers of the grid connection points of the i-th level other than the current grid connection point of the i-th level; the second load power is the sum of the load powers of the grid connection points of the i-th level other than the current grid connection point of the i-th level.

[0010] In some embodiments, after adjusting the second power to the difference between the first load power and the target demand power, the method further includes: re-determining the charge and discharge state of the energy storage system based on the adjusted second power; when the energy storage system is in a discharge state, determining whether to convert from a charging state to a discharge state based on a user instruction; if so, executing the discharge protection control; if not, adjusting the second power to 0; and when the energy storage system is in a charging state, maintaining the current second power.

[0011] In some embodiments, the energy storage system control method further includes: after adjusting the second power to 0, the energy management system controls the energy storage cabinet connected to the grid connection point at the i-th level to stop operating.

[0012] In some embodiments, when i is equal to N, the first target power is the power of the energy storage system determined according to a peak-valley mode.

[0013] In some embodiments, when i is less than N, the first target power acquired by the control module at the i-th level is the second target power issued by the control module at the (i+1)-th level.

[0014] In some embodiments, determining the second target power of the grid connection point or the energy storage cabinet at the i-1th level based on the adjusted second power and the first target power includes: the control module at the i-th level selects the smallest one between the first target power and the second power as the designated power; and determining the second target power based on the first power, the second power, and the designated power.

[0015] In some embodiments, determining the second target power based on the first power, the second power, and the specified power includes: determining the weight of the grid connection point or the energy storage cabinet at the i-1th level based on the first power and the second power; and obtaining the second target power of the grid connection point or the energy storage cabinet at the i-1th level based on the weight and the specified power.

[0016] In some embodiments, the second target power is calculated by the following formula: P0×P1 / P2; wherein P0 is the specified power, P1 is the first power, and P2 is the second power.

[0017] The technical solution provided by the embodiments of the present application has at least the following advantages: In an embodiment of the present application, multiple layers of virtual control modules are provided in the energy management system of the energy storage system. The control modules of each layer correspond to the actual grid connection points in the energy storage system. The control modules of each layer are used to obtain the first power reported by the grid connection points or energy storage cabinets at the next layer, summarize the first power to obtain the second power corresponding to the grid connection points at the current layer and adjust it. At the same time, the first target power corresponding to the grid connection points at the current layer is obtained, and the second target power of the grid connection points or energy storage cabinets at the next layer is determined based on the adjusted second power and the first target power. The second target power is then sent to the control modules or energy storage cabinets at the next layer. In this way, the multi-layer grid connection points of the energy storage system can be managed and controlled by only one energy management system, with low hardware cost. At the same time, the energy management system of the embodiment of the present application is directly connected to the energy storage cabinet, eliminating the intermediate EMS node in the traditional solution. The instructions of the energy management system can directly reach the bottom energy storage cabinet, with high collaborative efficiency. In addition, multiple virtual control modules are provided in the energy management system of the embodiment of the present application, which can accurately capture sudden changes in grid connection point power and quickly complete the response, and has high power control adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0019] Figure 1 is a structural diagram of an energy storage system according to an embodiment of the present application; Figure 2 is another structural schematic diagram of an energy storage system according to an embodiment of the present application; Figure 3 is a schematic structural diagram of an energy management system according to an embodiment of the present application; Figure 4 is a flow chart of a method for controlling an energy storage system according to an embodiment of the present application; Figure 5 is a flowchart of each sub-step of step 103 according to an embodiment of the present application; Figure 6 1 is a schematic diagram of an execution flow of charging protection control according to an embodiment of the present application; Figure 7 is a schematic diagram of an execution flow of discharge protection control according to an embodiment of the present application; Figure 8 is a flowchart of the sub-steps of step 105 according to an embodiment of the present application; Figure 9 It is a flowchart of the sub-steps of step 1052 according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] As can be seen from the background technology, the current energy storage system has problems such as high hardware cost, low coordination efficiency, and poor power control adaptability.

[0021] Analysis and research revealed that the current energy storage system has high hardware costs, low coordination efficiency, and poor power control adaptability due to the following reasons: In energy storage scenarios with multiple grid-connected points, each energy storage cabinet is equipped with Energy Management System (EMS) hardware. The cumulative costs of equipment procurement, installation, and maintenance increase project investment, and hardware redundancy leads to resource waste, resulting in high hardware costs. Data interaction and command coordination between multiple EMS hardware rely on complex communication protocols, which are prone to delays. This affects the real-time performance of power control functions such as backflow prevention and demand control at multiple grid-connected points, making it difficult to accurately achieve power regulation at different grid-connected points, resulting in low coordination efficiency. In addition, the energy management logic is concentrated in the main cabinet, lacking hierarchical control logic for multiple grid-connected points. This makes it impossible to flexibly configure power control strategies such as backflow prevention and overcapacity prevention according to the control requirements of different grid-connected points (such as transformer grid-connected points and low-voltage side grid-connected points). As a result, power control accuracy and scenario adaptability are poor, resulting in poor power control adaptability.

[0022] In order to solve the above technical problems, an embodiment of the present application provides a control method for an energy storage system, which is applied to an energy management system of an energy storage system, wherein the energy management system is connected to at least one energy storage cabinet through a switch; the energy storage system includes N levels of grid connection points, where N is an integer greater than 0; the grid connection point of the first level is connected to the energy storage cabinet, and the energy management system includes N levels of control modules, the grid connection point of the i-th level corresponds to the control module of the i-th level, 0<i≤N, and i is an integer; the control method of the energy storage system includes: the control module of the i-th level obtains a first power; when i is greater than 1, the first power is the first power reported by the control module of the i-1-th level. The power of the grid connection point at the i-1 level, when i is equal to 1, the first power is the power reported by the energy storage cabinet; the first power is aggregated to obtain the second power of the grid connection point at the i-th level; the second power is adjusted according to the preset rule to obtain the adjusted second power; when i is less than N, the control module at the i-th level reports the adjusted second power to the control module at the i+1-th level; the first target power of the grid connection point at the i-th level is obtained; the second target power of the grid connection point or the energy storage cabinet at the i-1-th level is determined based on the adjusted second power and the first target power, and is sent to the control module or the energy storage cabinet at the i-1-th level.

[0023] In an embodiment of the present application, multiple layers of virtual control modules are provided in the energy management system of the energy storage system. The control modules of each layer correspond to the actual grid connection points in the energy storage system. The control modules of each layer are used to obtain the first power reported by the grid connection points or energy storage cabinets at the next layer, summarize the first power to obtain the second power corresponding to the grid connection points at the current layer and adjust it. At the same time, the first target power corresponding to the grid connection points at the current layer is obtained, and the second target power of the grid connection points or energy storage cabinets at the next layer is determined based on the adjusted second power and the first target power. The second target power is then sent to the control modules or energy storage cabinets at the next layer. In this way, the multi-layer grid connection points of the energy storage system can be managed and controlled by only one energy management system, with low hardware cost. At the same time, the energy management system of the embodiment of the present application is directly connected to the energy storage cabinet, eliminating the intermediate EMS node in the traditional solution. The instructions of the energy management system can directly reach the bottom energy storage cabinet, with high collaborative efficiency. In addition, multiple virtual control modules are provided in the energy management system of the embodiment of the present application, which can accurately capture sudden changes in grid connection point power and quickly complete the response, and has high power control adaptability.

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present application, many technical details are proposed to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present application. The various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0025] Another embodiment of the present application relates to an energy storage system, such as Figure 1 As shown in FIG. 1 , a structural diagram of the energy storage system of this embodiment is shown. Figure 2 As shown, another structural schematic diagram of the energy storage system of this embodiment, the energy storage system of this embodiment includes: an energy management system, a switch, and an energy storage cabinet; the energy management system is connected to at least one energy storage cabinet via the switch; the energy storage system includes N levels of grid connection points, and the first level of grid connection points is connected to the energy storage cabinet.

[0026] like Figure 3As shown, it is a structural diagram of the energy management system of this embodiment. The energy management system of this embodiment includes N levels of control modules, the grid connection point of the i-th level corresponds to the control module of the i-th level, 0<i≤N, and i is an integer; the control module of the i-th level is configured to obtain a first power; when i is greater than 1, the first power is the power of the grid connection point of the i-1th level reported by the control module of the i-1th level, and when i is equal to 1, the first power is the power reported by the energy storage cabinet; the first power is aggregated to obtain the second power of the grid connection point of the i-th level; the second power is adjusted according to a preset rule to obtain the adjusted second power; the second power is reported to the control module of the i+1th level; the first target power of the grid connection point of the i-th level is obtained; the second target power of the grid connection point or the energy storage cabinet of the i-1th level is determined based on the adjusted second power and the first target power, and sent to the control module or energy storage cabinet of the i-1th level.

[0027] refer to Figure 2 The energy storage system of this embodiment further includes a grid connection point meter installed at each grid connection point. The grid connection point meter can be a smart meter and / or a demand meter. The smart meter and / or demand meter can monitor the real-time load demand and real-time load power of the grid connection point in real time for subsequent demand control protection and anti-backflow control protection.

[0028] pass Figure 1 、 Figure 2 、 Figure 3 As can be seen, the N levels of control modules in the energy management system of this embodiment form a multi-level relationship with the energy storage cabinets. The first-level control module is used to obtain the power reported by the energy storage cabinets. The first-level control module aggregates the power reported by the energy storage cabinets and then reports it to the second-level control module. This process continues layer by layer, until the Nth-level control module is reached. The figure shows a three-level grid connection point structure. In actual applications, the grid connection point level can be 1, 2, 4, or other levels.

[0029] In terms of hardware deployment, this embodiment only deploys a set of local EMS hardware in the control room of the energy storage system. To adapt to the scenario and data volume, the EMS hardware uses industrial-grade servers, industrial computers, or embedded devices. It has multiple network ports and high computing power to meet the requirements of multi-level data processing and command concurrency. The EMS hardware is connected to an industrial Ethernet switch and serves as the core hub for multi-layer grid connection point power control, uniformly collecting, processing, and issuing data and commands.

[0030] Specifically, the energy storage cabinet includes an energy storage inverter, a battery management system (BMS), a protocol converter, and at least one functional module. The energy management system is connected to the energy storage inverter, battery management system, and protocol converter via a switch. The protocol converter is also connected to at least one functional module. Functional modules can include fire protection systems, liquid cooling units, temperature and humidity sensors, etc. within the energy storage cabinet. The energy storage inverter and battery management system support Modbus-TCP or other network protocols and directly connect to the switch to communicate with the local EMS. Functional modules such as the fire protection system, liquid cooling units, and temperature and humidity sensors within the energy storage cabinet do not support network protocols and are connected after converting the protocol via a protocol converter (such as an RS485 to Ethernet converter), ensuring that all devices in the underlying energy storage cabinet are fully connected.

[0031] Specifically, each control module and each energy storage cabinet is provided with corresponding identity information, such as ID (Identification), to distinguish the hierarchical relationship between multiple control modules. When reporting or sending the corresponding power, each will carry its own ID information, so that the corresponding control module and energy storage cabinet can identify the corresponding power, thereby improving the accuracy of energy storage system control.

[0032] In the traditional multi-EMS architecture, power control instructions must pass through the master EMS to the slave EMS and then to the converter PCS in the energy storage cabinet. This involves a long transmission link and high communication latency. Furthermore, the slave EMS must first parse the master instructions before forwarding them to the converter in the energy storage cabinet. This, combined with the time-consuming protocol conversion, leads to response delays in scenarios with high real-time requirements, such as backflow prevention and demand control.

[0033] The energy storage system of this embodiment only has one energy management system, which not only enables the management and control of the energy storage system's multi-level grid connection points, but also reduces hardware costs. Furthermore, the energy management system is connected to the energy storage cabinets via a switch, eliminating the intermediate EMS node in traditional solutions. Instructions from the energy management system can be directly transmitted to the underlying energy storage cabinets, improving collaborative efficiency. Furthermore, multiple virtual control modules are provided within the energy management system, which can accurately capture sudden power changes at the grid connection points and quickly respond, achieving high power control adaptability.

[0034] Another embodiment of the present application relates to a control method for an energy storage system, which is applied to an energy management system of the energy storage system. Figure 1 、 Figure 2 、 Figure 3 The energy management system is connected to at least one energy storage cabinet through a switch; the energy storage system includes N levels of grid connection points, where N is an integer greater than 0; the grid connection point of the first level is connected to the energy storage cabinet; the energy management system includes N levels of control modules, the grid connection point of the i-th level corresponds to the control module of the i-th level, 0<i≤N, and i is an integer.

[0035] like Figure 4 FIG. 1 is a flow chart of a method for controlling an energy storage system according to an embodiment of the present invention. The method for controlling an energy storage system according to an embodiment of the present invention includes the following steps: Step 101: A control module at the i-th level obtains a first power.

[0036] The executor of this embodiment is an energy management system, which includes N levels of control modules. The grid connection point of the i-th level corresponds to the control module of the i-th level. For any control module of the i-th level, the first power P1 of the control module of the next level or the energy storage cabinet is obtained.

[0037] Specifically, when i is greater than 1, the first power P1 is the power of the grid connection point at the i-1th level reported by the control module at the i-1th level; when i is equal to 1, the first power P1 is the power reported by the energy storage cabinet.

[0038] Step 102: Summarize the first powers to obtain the second powers of the grid connection points at the i-th level.

[0039] Specifically, the control module at level i corresponds to the grid connection point at level i. When i is greater than 1, the grid connection point at level i is connected to the grid connection point at level i-1. The power of the grid connection point at level i-1 is reported by the control module at level i-1. Therefore, the control module at level i aggregates the first power P1 reported by the control modules at level i-1 to obtain the second power P2 of the grid connection point at level i. When i is equal to 1, the grid connection point at level one is connected to the energy storage cabinet at the bottom layer. The energy storage cabinet reports its first power P1 to the control module at level one. The control module at level one aggregates the first power P1 reported by the energy storage cabinet to obtain the second power P2 of the grid connection point at level one.

[0040] Step 103: Adjust the second power according to a preset rule to obtain an adjusted second power.

[0041] Specifically, when i is less than N, the control module at the i-th level reports the adjusted second power P2 to the control module at the i+1-th level for aggregation by the control module at the i+1-th level. When i is equal to N, the control module at the highest level, i.e., the control module at the N-th level, directly calculates the second target power of the grid connection point or energy storage cabinet at the N-1-th level based on the second power P2.

[0042] In this embodiment, after the control module at the i-th level aggregates the first power P1 to obtain the second power P2 of the i-th grid connection point, it adjusts the second power P2 according to a preset rule, thereby improving the accuracy of the second power P2 of the i-th grid connection point. For example, when adjusting the second power P2, the control module at the i-th level can combine the control logic of demand control protection and anti-backflow control protection. Demand control protection prevents overload and damage to equipment in the energy storage system, such as transformers and lines, by limiting the user's maximum demand. Anti-backflow control protection can prevent the grid voltage from increasing and avoid damage to user equipment on the grid side. Therefore, the second power P2 is adjusted through demand control protection and anti-backflow control protection, thereby ensuring the safe operation of the energy storage system.

[0043] like Figure 5 FIG. 1 is a flow chart of each sub-step of step 103. Step 103 includes the following sub-steps: Step 1031 : The control module at the i-th level obtains the charge and discharge status of the energy storage system according to the second power before adjustment.

[0044] Step 1032: When the energy storage system is in a charging state, perform charging protection control.

[0045] Step 1033: When the energy storage system is in a discharging state, discharge protection control is performed.

[0046] In this embodiment, the second power P2 of the i-th grid-connected point obtained by aggregation can be used to determine the charge and discharge status of the energy storage system. When the second power P2 is positive, the energy storage system is in a discharge state and discharge protection control is executed. When the second power P2 is negative, the energy storage system is in a charge state and charge protection control is executed. The corresponding protection control mode can be used according to the charge and discharge status of the energy storage system to ensure the safety of the energy storage system during operation.

[0047] The charging protection control of this embodiment can be demand control protection, and the discharging protection control can be anti-backflow control protection. By performing demand control protection and anti-backflow control protection during the charging and discharging processes of the energy storage system, the safety of the energy storage system during operation is improved.

[0048] like Figure 6 The figure shows the execution flow of charging protection control, which includes the following steps: Step 10321: Determine whether the sum of the second power and the first load power is greater than the target demand power.

[0049] If so, proceed to step 10322 to adjust the second power P2 to the difference between the first load power and the target demand power; if not, proceed to step 10323 to maintain the current second power P2.

[0050] Step 10322: Adjust the second power to the difference between the first load power and the target demand power.

[0051] Step 10323, maintain the current second power.

[0052] Specifically, the first load power P3 is the sum of the demand power of the grid connection points of the i-th level except the current grid connection point of the i-th level, Figure 1 For a first-tier grid-connected point, the second power P2 is the sum of the first powers P1 of all energy storage cabinets under the grid-connected point, and the sum of the demand powers of other first-tier grid-connected points of the same tier as the grid-connected point is the first load power P3; for a second-tier grid-connected point, the second power P2 is the sum of the first powers P1 of all energy storage cabinets under the grid-connected point, and the sum of the demand powers of other second-tier grid-connected points of the same tier as the grid-connected point is the first load power P3.

[0053] Each grid connection point is equipped with a grid connection point meter, such as a smart meter and / or demand meter. The smart meter and / or demand meter can monitor the real-time load demand and real-time load power of the grid connection point in real time. The demand power of other grid connection points at the i-th level can be obtained by smart meters and / or demand meters installed at other grid connection points at the i-th level. In this embodiment, the real-time load demand monitored by the smart meter and / or demand meter is required to calculate the first load power P3. After the smart meter and / or demand meter detects the real-time load demand of other grid connection points at the i-th level, it reports it to the energy management system. The energy management system can then calculate the sum of the real-time load demand of other grid connection points at the i-th level as the first load power P3.

[0054] In this embodiment, the second power P2 is the charging power, which is generally expressed as a negative number. Therefore, in this embodiment, the calculation of the sum of the second power P2 and the first load power P3 is actually the calculation of the sum of the absolute value of the second power P2 and the absolute value of the first load power P3. In this way, by calculating the sum of the second power P2 and the first load power P3, the total power of all i-level grid-connected points is obtained and compared with the target demand power P4. If the sum of the second power P2 and the first load power P3 is greater than the target demand power P4, it means that the total power of all i-level grid-connected points exceeds the target demand power P4, and the second power P2 of the current i-level grid-connected point needs to be adjusted, and the second power P2 is adjusted to the difference between the first load power P3 and the target demand power P4. By adjusting the second power P2, the total power of all i-level grid-connected points is within the target demand power P4; if the sum of the second power P2 and the first load power P3 is less than or equal to the target demand power P4, it means that the total power of all i-level grid-connected points does not exceed the target demand power P4, and the current second power P2 is maintained.

[0055] Specifically, if the total power of other i-level grid-connected points, that is, the first load power P3, is less than the target demand power P4, at this time, the second power P2 is adjusted to the difference between the first load power P3 and the target demand power P4, and the obtained second power P2 is still a negative value, indicating that the second power P2 is still charging power, and the charging state of the second power P2 has not changed, and the current adjusted second power P2 can be maintained; if the total power of other i-level grid-connected points, that is, the load power, is greater than the target demand power P4, at this time, the second power P2 is adjusted to the difference between the first load power P3 and the target demand power P4. If the second power P2 is adjusted, the obtained second power P2 is a positive value, indicating that the second power P2 is converted into discharging power, and the second power P2 is converted from the charging state to the discharging state. Therefore, it is necessary to further determine whether to switch to the charging state according to user instructions to further adjust the second power P2.

[0056] It should be noted that the difference between the first load power P3 and the target demand power P4 is P3-P4. If the first load power P3 is less than the target demand power P4, the adjusted second power P2 is negative. If the first load power P3 is greater than the target demand power P4, the adjusted second power P2 is positive. If the adjusted second power P2 is positive, it indicates that the second power P2 is the discharge power. If the second power P2 is negative, it indicates that the second power P2 is the charging power.

[0057] Therefore, this embodiment further includes, after step 10322, adjusting the second power P2 to the difference between the first load power P3 and the target demand power P4: Step 10324: Re-determine the charge and discharge state of the energy storage system based on the adjusted second power.

[0058] When the energy storage system is in a discharging state, proceed to step 10325 ; when the energy storage system is in a charging state, proceed to step 10329 .

[0059] Step 10325: When the energy storage system is in the discharging state, determine whether to switch from the charging state to the discharging state according to a user instruction.

[0060] If so, proceed to step 10326 to perform discharge protection control; if not, proceed to step 10327 to adjust the second power P2 to 0.

[0061] Step 10326, execute discharge protection control.

[0062] Step 10327, adjust the second power to 0.

[0063] This embodiment further includes the following steps after step 10327, i.e., after adjusting the second power to 0: In step 10328, the energy management system controls the energy storage cabinets connected to the grid connection point at the i-th level to stop operating.

[0064] Step 10329: When the energy storage system is in a charging state, the current second power is maintained.

[0065] Specifically, when it is detected that the adjusted second power P2 is the charging power, the energy storage system is in the charging state, and the current second power P2 is maintained; when it is detected that the adjusted second power P2 is the discharging power, the user will be prompted whether to switch to the discharging state. If the user issues an instruction to switch to the discharging state, the discharge protection control is performed, that is, the following steps 10331 to 10333 are executed; if the user does not instruct to switch to the discharging state, in order to ensure the safety of the energy storage system, at this time, the second power P2 is adjusted to 0, and all energy storage systems connected to the current grid-connected point stop operating.

[0066] like Figure 7 FIG. 1 is a flow chart showing the execution of discharge protection control, which includes the following steps: Step 10331: Determine whether the second power is greater than the difference between the second load power and the minimum off-grid power.

[0067] If so, proceed to step 10332 to adjust the second power to the difference between the second load power and the minimum off-grid power; if not, proceed to step 10333 to maintain the current second power.

[0068] Step 10332: The second power is adjusted to the difference between the second load power and the minimum off-grid power.

[0069] Step 10333, maintain the current second power.

[0070] Specifically, the minimum off-grid power P5 is the protection threshold set in the anti-backflow control protection. When the power transmitted by the grid to the load side (i.e., the "off-grid power") is lower than or equal to the minimum off-grid power, the anti-backflow control protection process will determine that the local energy storage system's power generation has approached or exceeded the load demand, thereby triggering power limit or removal of some power generation equipment, that is, limiting the energy storage system's power generation to prevent backflow. When the power transmitted by the grid to the load side is greater than this value, the system considers the load to be large enough and allows the energy storage system to generate full power.

[0071] Specifically, the second load power P6 is the sum of the load powers of other i-th-level grid connection points except the current i-th-level grid connection point; each grid connection point in this embodiment is equipped with a grid connection point meter such as a smart meter and / or a demand meter, and the smart meter and / or demand meter can monitor the real-time load demand and the real-time load power of the grid connection point in real time. This embodiment needs to use the real-time load power monitored by the smart meter and / or demand meter to calculate the second load power P6. After the smart meter and / or demand meter detects the real-time load power of other i-th-level grid connection points, it reports it to the energy management system. The energy management system can calculate the sum of the real-time load powers of other i-th-level grid connection points, which is the second load power P6.

[0072] In this embodiment, the second power P2 is the discharge power, which is generally expressed as a positive number. The difference between the second load power P6 and the minimum off-grid power P5 obtained in this embodiment is the absolute value of the difference between the second load power P6 and the minimum off-grid power P5.

[0073] If the second power P2 is greater than the difference between the second load power P6 and the minimum off-grid power P5, it means that the sum of the second load power P6 and the second power P2 of the current i-th grid-connected point exceeds the minimum off-grid power P5, indicating that the total discharge power of the energy storage system exceeds the minimum off-grid power P5. The local energy storage system's power generation has approached or exceeded the load demand, and it is necessary to trigger power limit or remove some power generation equipment, that is, limit the energy storage system's power generation to prevent backflow. Therefore, the second power P2 is adjusted to the difference between the second load power P6 and the minimum off-grid power P5, so that the sum of the second load power P6 and the second power P2 of the current i-th grid-connected point, that is, the total discharge power of the energy storage system, is within the range of the minimum off-grid power P5. If the second power P2 is less than or equal to the difference between the second load power P6 and the minimum off-grid power P5, it means that the sum of the second load power P6 and the second power P2 of the current i-th grid-connected point does not exceed the minimum off-grid power P5, indicating that the total discharge power of the energy storage system does not exceed the minimum off-grid power P5, and the power generation of the local energy storage system does not exceed the load demand. Therefore, the current second power P2 is maintained at this time.

[0074] Step 104: Obtain a first target power of the grid connection point at the i-th level.

[0075] Specifically, when i equals N, the first target power is the power of the energy storage system determined according to the peak-valley mode. This embodiment can determine the charge and discharge state of the energy storage system based on the first target power. When the energy storage system is in the discharging state, the second power P2 is the dischargeable power, and when the energy storage system is in the charging state, the second power P2 is the chargeable power. The peak-valley mode is an economic optimization operation strategy for energy storage systems. Its core purpose is to control the energy storage system to charge during low-price periods and discharge during peak periods, thereby reducing the energy storage system's electricity costs and increasing its profitability.

[0076] Specifically, when i is less than N, the first target power acquired by the control module at the i-th level is the second target power issued by the control module at the (i+1)-th level.

[0077] Step 105 : Determine the second target power of the grid connection point or energy storage cabinet at the i-1th level according to the adjusted second power and the first target power, and send it to the control module or energy storage cabinet at the i-1th level.

[0078] In this embodiment, the second target power of the next-level grid connection point or energy storage cabinet can be calculated based on the adjusted second power P2 and the first target power. Figure 1 , the first-level grid connection point obtains the adjusted second power P2 and the first target power issued by the second-level grid connection point, the first-level grid connection point calculates the second target power of the energy storage cabinet and sends it to each energy storage cabinet; the second-level grid connection point obtains the adjusted second power P2 and the first target power issued by the third-level grid connection point, the second-level grid connection point calculates the second target power of the first-level grid connection point, and sends it to each first-level grid connection point; this cycle continues, the highest-level grid connection point obtains the adjusted second power P2 and the first target power determined according to the peak-valley mode, the highest-level grid connection point calculates the second target power of the second-level grid connection point, and sends it to each second-level grid connection point.

[0079] like Figure 8 FIG. 1 is a flow chart of the sub-steps of step 105. Step 105 includes the following sub-steps: In step 1051 , the control module at the i-th level selects the smallest one between the first target power and the second power as the designated power.

[0080] Step 1052: Determine a second target power according to the first power, the second power, and the designated power.

[0081] In this embodiment, if the first target power is greater than the second power P2, it means that the first target power determined by the previous level grid connection point or the peak-valley mode exceeds the power that the current grid connection point can withstand. Therefore, the second power P2 is selected as the designated power P0 to ensure the safety of the energy storage system. If the first target power is greater than the second power P2, it means that the first target power determined by the previous level grid connection point or the peak-valley mode is less than the power that the current grid connection point can withstand. The system can operate according to the first target power determined by the previous level grid connection point or the peak-valley mode. Therefore, the first target power is selected as the designated power P0, thereby ensuring a low electricity cost for the energy storage system. That is, this embodiment takes the smaller of the first target power and the second power P2 into account, thereby balancing the safety and electricity cost of the energy storage system.

[0082] like Figure 9 FIG. 1 is a flow chart of the sub-steps of step 1052. Step 1052 includes the following sub-steps: Step 10521: Determine the weight of the grid connection point or energy storage cabinet at the i-1th level according to the first power and the second power.

[0083] Step 10522: Obtain the second target power of the grid connection point or energy storage cabinet at the i-1th level according to the weight and the specified power.

[0084] Specifically, the second target power is calculated by the following formula: P0×P1 / P2; wherein P0 is the specified power, P1 is the first power, and P2 is the second power.

[0085] Specifically, after the grid connection point or energy storage cabinet of the i-1th level reports the first power P1, the grid connection points of the i-th level summarize the first power P1 to obtain the second power P2, and the weight of each grid connection point or energy storage cabinet of the i-1th level can be obtained according to the proportion of each first power P1 to the second power P2; for example, the grid connection point of the first level obtains the first power P1 reported by the bottom energy storage cabinet, and summarizes it to obtain the second power P2, and the weight of each energy storage cabinet can be obtained according to the ratio of the first power P1 to the second power P2 of each energy storage cabinet, and the second target power of each energy storage cabinet can be obtained according to the weight of each energy storage cabinet and the specified power P0; the grid connection point of the second level obtains the first power P1 reported by the grid connection point of the first level, and summarizes it to obtain the second target power P2. The second power P2, the weight of each first-level grid connection point can be obtained according to the ratio of the first power P1 to the second power P2 of each first-level grid connection point, and the second target power of each first-level grid connection point can be obtained according to the weight of each first-level grid connection point and the designated power P0; and so on, the grid connection point of the Nth level obtains the first power P1 reported by the grid connection point of the N-1th level, and summarizes it to obtain the second power P2, and the weight of each N-1th level grid connection point can be obtained according to the ratio of the first power P1 to the second power P2 of each N-1th level grid connection point, and the second target power of each N-1th level grid connection point can be obtained according to the weight of each N-1th level grid connection point and the designated power P0.

[0086] In this embodiment, multiple layers of virtual control modules are provided in the energy management system of the energy storage system. The control modules of each layer correspond to the actual grid connection points in the energy storage system. The control modules of each layer are used to obtain the first power P1 reported by the grid connection points or energy storage cabinets at the next layer, summarize the first power P1 to obtain the second power P2 corresponding to the grid connection points at the current layer and adjust it. At the same time, the first target power corresponding to the grid connection points at the current layer is obtained. The second target power of the grid connection points or energy storage cabinets at the next layer is determined based on the adjusted second power P2 and the first target power, and is sent to the control modules or energy storage cabinets at the next layer. In this way, the multi-level grid connection points of the energy storage system can be managed and controlled by only providing a single energy management system, which reduces hardware costs. At the same time, the energy management system of the embodiment of the present application is directly connected to the energy storage cabinet, eliminating the intermediate EMS node in the traditional solution. The instructions of the energy management system can directly reach the bottom energy storage cabinet, which has high collaborative efficiency. In addition, multiple virtual control modules are provided in the energy management system of the embodiment of the present application, which can accurately capture sudden changes in grid connection point power and quickly complete responses, and has high power control adaptability.

[0087] This embodiment reduces the amount of local EMS hardware required for energy storage systems, lowering equipment procurement, installation, and operation and maintenance costs. Hardware costs for industrial and commercial multi-layer grid-connected point energy storage projects can be reduced by 35%-45%, effectively alleviating hardware cost pressures for energy storage systems. Furthermore, this embodiment coordinates virtual logic layers with real control layers to accommodate the differentiated control requirements of industrial and commercial multi-layer grid-connected points (e.g., transformer side, low-voltage side, etc.). Power control strategies such as backflow protection and demand control are more accurately executed, improving power control accuracy at multi-layer grid-connected points by over 35%. Furthermore, the single EMS hardware architecture reduces latency associated with multi-device coordination, increasing policy response speed by over 30%, significantly enhancing the real-time and accuracy of power control at multi-layer grid-connected points and ensuring the safe and efficient operation of the energy storage system.

[0088] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A control method for an energy storage system, characterized in that: An energy management system applied to an energy storage system, the energy management system being connected to at least one energy storage cabinet via a switch; the energy storage system comprising N levels of grid connection points, where N is an integer greater than 0; the grid connection points of the first level being connected to the energy storage cabinet, the energy management system comprising N levels of control modules, the grid connection points of the i-th level corresponding to the control modules of the i-th level, where 0 < i ≤ N, and i is an integer; The control method of the energy storage system includes: The control module at the i-th level obtains a first power; when i is greater than 1, the first power is the power of the grid connection point at the i-1-th level reported by the control module at the i-1-th level; when i is equal to 1, the first power is the power reported by the energy storage cabinet; aggregating the first powers to obtain a second power of the grid connection point at the i-th level; adjusting the second power according to a preset rule to obtain an adjusted second power; when i is less than N, the control module at the i-th level reports the adjusted second power to the control module at the (i+1)-th level; Obtaining a first target power of the grid connection point at the i-th level; The second target power of the grid connection point or the energy storage cabinet at the i-1th level is determined according to the adjusted second power and the first target power, and is sent to the control module or the energy storage cabinet at the i-1th level.

2. The control method of the energy storage system according to claim 1, characterized in that: The adjusting the second power according to a preset rule to obtain the adjusted second power includes: The control module at the i-th level obtains the charge and discharge status of the energy storage system according to the second power before adjustment; When the energy storage system is in a charging state, performing charging protection control; When the energy storage system is in a discharging state, discharge protection control is performed.

3. The control method of the energy storage system according to claim 2, characterized in that: The charging protection control comprises: determining whether the sum of the second power and the first load power is greater than the target demand power; if so, adjusting the second power to the difference between the first load power and the target demand power; if not, maintaining the current second power; The discharge protection control is as follows: determining whether the second power is greater than the difference between the second load power and the minimum grid-off power; if so, adjusting the second power to the difference between the second load power and the minimum grid-off power; if not, maintaining the current second power.

4. The control method of the energy storage system according to claim 3, characterized in that: The first load power is the sum of the demand powers of the grid connection points of the i-th level except the current grid connection point of the i-th level; the second load power is the sum of the load powers of the grid connection points of the i-th level except the current grid connection point of the i-th level.

5. The control method of the energy storage system according to claim 3, characterized in that: After adjusting the second power to the difference between the first load power and the target demand power, the method further includes: re-determining the charge and discharge state of the energy storage system according to the adjusted second power; When the energy storage system is in a discharging state, determining whether to switch from a charging state to a discharging state according to a user instruction; if so, executing the discharge protection control; if not, adjusting the second power to 0; When the energy storage system is in a charging state, the current second power is maintained.

6. The control method of the energy storage system according to claim 5, characterized in that: The control method of the energy storage system further includes: After adjusting the second power to 0, the energy management system controls the energy storage cabinet connected to the grid connection point at the i-th level to stop operating.

7. The control method of the energy storage system according to claim 1, characterized in that: When i is equal to N, the first target power is the power of the energy storage system determined according to the peak-valley mode.

8. The control method of the energy storage system according to claim 1, characterized in that: When i is less than N, the first target power acquired by the control module at the i-th level is the second target power issued by the control module at the (i+1)-th level.

9. The control method of the energy storage system according to claim 1, characterized in that: The determining the second target power of the grid connection point or the energy storage cabinet at the (i-1)th level according to the adjusted second power and the first target power includes: The control module at the i-th level selects the smallest one between the first target power and the second power as the designated power; The second target power is determined according to the first power, the second power, and the designated power.

10. The control method of the energy storage system according to claim 9, characterized in that: The determining the second target power according to the first power, the second power, and the specified power includes: Determine the weight of the grid connection point or the energy storage cabinet at the i-1th level according to the first power and the second power; and obtain the second target power of the grid connection point or the energy storage cabinet at the i-1th level according to the weight and the specified power.

11. The control method of the energy storage system according to claim 10, characterized in that: The second target power is calculated by the following formula: P0×P1 / P2; Wherein, P0 is the specified power, P1 is the first power, and P2 is the second power.

12. An energy storage system, characterized in that: include: Energy management systems, switches, and energy storage cabinets; The energy management system is connected to at least one of the energy storage cabinets via the switch; the energy storage system includes N levels of grid connection points, the grid connection points of the first level are connected to the energy storage cabinet, and the energy management system includes N levels of control modules, the grid connection points of the i-th level correspond to the control modules of the i-th level, 0<i≤N, and i is an integer; The control module at the i-th level is configured to obtain a first power; when i is greater than 1, the first power is the power of the grid connection point at the i-1th level reported by the control module at the i-1th level; when i is equal to 1, the first power is the power reported by the energy storage cabinet; the first power is aggregated to obtain a second power of the grid connection point at the i-th level; the second power is adjusted according to a preset rule to obtain the adjusted second power; and the second power is reported to the control module at the i+1th level; Obtain the first target power of the grid connection point at the i-th level; determine the second target power of the grid connection point or the energy storage cabinet at the i-1th level based on the adjusted second power and the first target power, and send it to the control module or the energy storage cabinet at the i-1th level.

13. The energy storage system according to claim 12, characterized in that: The energy storage cabinet includes: an energy storage converter, a battery management system, a protocol converter, and at least one functional module; The energy management system is connected to the energy storage converter, the battery management system, and the protocol converter through the switch; the protocol converter is also connected to at least one of the functional modules.

14. The energy storage system according to claim 12, characterized in that: The energy storage system further includes a grid connection point meter provided at each of the grid connection points, wherein the grid connection point meter is a smart meter and / or a demand meter.

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