Control method of energy storage system and energy storage system

Abstract

The application 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 following steps: a control module at an i-th level acquires first power; second power of a grid-connected point at the i-th level is obtained by aggregating the first power; the second power is adjusted according to a preset rule to obtain adjusted second power; in the case that i is less than N, the control module at the i-th level reports the adjusted second power to a control module at an (i+1)-th level; a first target power of the grid-connected point at the i-th level is acquired; second target power of the grid-connected point at an (i-1)-th level or an energy storage cabinet is determined according to the adjusted second power and the first target power, and is delivered to the control module at the (i-1)-th level or the energy storage cabinet; thereby, the hardware cost of the energy storage system is reduced, the collaborative efficiency of the energy storage system is improved, and the power control is adapted to be high.

Description

Technical Field

[0001] This 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 Technology

[0002] Currently, traditional energy storage systems employ a configuration of multiple local EMS hardware. Each energy storage cabinet is configured as a slave cabinet and connected to the master cabinet via communication lines, forming a master-slave architecture. Each master cabinet and slave cabinet is equipped with an independent EMS.

[0003] However, current energy storage systems suffer from high hardware costs, low coordination efficiency, and poor power control compatibility. Summary of the Invention

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

[0005] To address the aforementioned technical problems, embodiments of this application provide a control method for an energy storage system, applied to the energy management system of the energy storage system. The energy management system is connected to at least one energy storage cabinet via a switch. The energy storage system includes N levels of grid connection points, where N is an integer greater than 0. The first level of grid connection points connects to the energy storage cabinet. The energy management system includes N levels of control modules, where the i-th level of grid connection point corresponds to the i-th level of control module, 0 < i ≤ N, and i is an integer. The control method for the energy storage system includes: the i-th level control module acquiring a first power; when i is greater than 1, the first power is the first power reported by the (i-1)-th level control module. The power of the grid connection point at level i-1 is determined as follows: when i equals 1, the first power is the power reported by the energy storage cabinet; the first power is summarized to obtain the second power of the grid connection point at level i; the second power is adjusted according to a preset rule to obtain the adjusted second power; when i is less than N, the control module at level i reports the adjusted second power to the control module at level i+1; the first target power of the grid connection point at level i is obtained; the second target power of the grid connection point or the energy storage cabinet at level i-1 is determined based on the adjusted second power and the first target power, and then sent to the control module or the energy storage cabinet at level i-1.

[0006] An embodiment of this application also provides an energy storage system, including: 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 through the switch; the energy storage system includes N levels of grid connection points, the first level of grid connection points is connected to the energy storage cabinets, the energy management system includes N levels of control modules, the i-th level of grid connection point corresponds to the i-th level of control module, 0 < i ≤ N, and i is an integer; the i-th level of control module is configured to acquire a first power; when i is greater than 1, the first power is the i-th power reported by the (i-1)-th level of control module. The power of the grid connection point at level -1, when i equals 1, the first power is the power reported by the energy storage cabinet; the first power is summarized to obtain the second power of the grid connection point at level i; 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 at level i+1; the first target power of the grid connection point at level i is obtained; the second target power of the grid connection point or the energy storage cabinet at level i-1 is determined according to the adjusted second power and the first target power, and then sent to the control module or the energy storage cabinet at level i-1.

[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 charging and discharging state of the energy storage system based on the second power before adjustment; performing charging protection control when the energy storage system is in a charging state; and performing discharging protection control when the energy storage system is in a discharging state.

[0008] In some embodiments, the charging protection control is as follows: determining whether the sum of the second power and the first load power is greater than the target demand power; if yes, adjusting the second power to the difference between the first load power and the target demand power; if no, maintaining the current second power; the discharging protection control is as follows: determining whether the second power is greater than the difference between the second load power and the minimum grid disconnection power; if yes, adjusting the second power to the difference between the second load power and the minimum grid disconnection power; if no, maintaining the current second power.

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

[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 / discharge state of the energy storage system based on the adjusted second power; if 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 yes, executing the discharge protection control; if no, adjusting the second power to 0; and if the energy storage system is in a charging state, maintaining the current second power.

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

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

[0013] In some embodiments, when i is less than N, the first target power obtained 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-1)th level based on the adjusted second power and the first target power includes: the control module at the i-th level selecting the smaller of the first target power and the second power as the specified power; and determining the second target power based on the first power, the second power, and the specified 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-1)th 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-1)th 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; where P0 is the specified power, P1 is the first power, and P2 is the second power.

[0017] The technical solution provided in this application has at least the following advantages:

[0018] This application embodiment sets up a multi-layer virtual control module in the energy management system of the energy storage system. Each layer of the control module corresponds to an actual grid connection point in the energy storage system. Each layer of the control module is used to obtain the first power reported by the next-level grid connection point or energy storage cabinet, summarize the first power to obtain the second power corresponding to the grid connection point at this level and adjust it. At the same time, it obtains the first target power corresponding to the grid connection point at this level, determines the second target power of the next-level grid connection point or energy storage cabinet based on the adjusted second power and the first target power, and sends it to the control module or energy storage cabinet at the next level. Thus, the control of the multi-level grid connection points of the energy storage system can be realized by setting up only one energy management system, with low hardware cost. At the same time, the energy management system of this application embodiment 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 coordination efficiency. Furthermore, the energy management system of this application embodiment sets up multiple virtual control modules, which can accurately capture power changes at the grid connection point and quickly complete the response, with high power control adaptability. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 This is a schematic diagram of an energy storage system according to an embodiment of this application;

[0021] Figure 2 This is another structural schematic diagram of an energy storage system according to an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the structure of an energy management system according to an embodiment of this application;

[0023] Figure 4 This is a schematic flowchart of a control method for an energy storage system according to an embodiment of this application;

[0024] Figure 5 This is a flowchart illustrating each sub-step of step 103 according to an embodiment of this application;

[0025] Figure 6 This is a schematic diagram of the execution flow of charging protection control according to an embodiment of this application;

[0026] Figure 7 This is a schematic diagram of the execution flow of discharge protection control according to an embodiment of this application;

[0027] Figure 8This is a flowchart illustrating the various sub-steps of step 105 according to an embodiment of this application;

[0028] Figure 9 This is a flowchart illustrating the various sub-steps of step 1052 according to an embodiment of this application. Detailed Implementation

[0029] As can be seen from the background technology, current energy storage systems suffer from high hardware costs, low coordination efficiency, and poor power control adaptation.

[0030] Analysis revealed that the high hardware cost, low coordination efficiency, and poor power control adaptability of current energy storage systems are due to the following reasons: In multi-level grid-connected energy storage scenarios, each energy storage cabinet is equipped with an 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 anti-reverse current and demand control at multi-level grid-connected points, making it difficult to accurately achieve power regulation at different levels of grid-connected points, resulting in low coordination efficiency. Furthermore, the energy management logic is concentrated in the main cabinet, lacking hierarchical control logic for multi-level grid-connected points. It is impossible to flexibly configure power control strategies such as anti-reverse current and anti-overcapacity based on the control requirements of different levels of grid-connected points (such as transformer grid-connected points and low-voltage side grid-connected points). This results in poor power control accuracy and scenario adaptability, leading to poor power control adaptability.

[0031] To address the aforementioned technical problems, this application provides a control method for an energy storage system, applied to the energy management system of the energy storage system. The energy management system is connected to at least one energy storage cabinet via a switch. The energy storage system includes N levels of grid connection points, where N is an integer greater than 0. The first level of grid connection points connects to the energy storage cabinet. The energy management system includes N levels of control modules, where the i-th level of grid connection point corresponds to the i-th level of control module, 0 < i ≤ N, and i is an integer. The control method for the energy storage system includes: the i-th level control module acquiring a first power; when i is greater than 1, the first power is the first power reported by the (i-1)-th level control module. The power of the grid connection point at level i-1 is determined as follows: when i equals 1, the first power is the power reported by the energy storage cabinet; the first power is summarized to obtain the second power of the grid connection point at level i; the second power is adjusted according to a preset rule to obtain the adjusted second power; when i is less than N, the control module at level i reports the adjusted second power to the control module at level i+1; the first target power of the grid connection point at level i is obtained; the second target power of the grid connection point or the energy storage cabinet at level i-1 is determined based on the adjusted second power and the first target power, and then sent to the control module or the energy storage cabinet at level i-1.

[0032] This application embodiment sets up a multi-layer virtual control module in the energy management system of the energy storage system. Each layer of the control module corresponds to an actual grid connection point in the energy storage system. Each layer of the control module is used to obtain the first power reported by the next-level grid connection point or energy storage cabinet, summarize the first power to obtain the second power corresponding to the grid connection point at this level and adjust it. At the same time, it obtains the first target power corresponding to the grid connection point at this level, determines the second target power of the next-level grid connection point or energy storage cabinet based on the adjusted second power and the first target power, and sends it to the control module or energy storage cabinet at the next level. Thus, the control of the multi-level grid connection points of the energy storage system can be realized by setting up only one energy management system, with low hardware cost. At the same time, the energy management system of this application embodiment 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 coordination efficiency. Furthermore, the energy management system of this application embodiment sets up multiple virtual control modules, which can accurately capture power changes at the grid connection point and quickly complete the response, with high power control adaptability.

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this application to help readers better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0034] Another embodiment of this application relates to an energy storage system, such as Figure 1 The diagram shown is a structural schematic of the energy storage system in this embodiment. Figure 2 The diagram shown is another structural schematic of the energy storage system in this embodiment. The energy storage system in 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 through the switch; the energy storage system includes N levels of grid connection points, and the first level of grid connection point is connected to the energy storage cabinet.

[0035] like Figure 3 The diagram shows the structure of the energy management system in this embodiment. The energy management system includes N levels of control modules. The grid connection point at level i corresponds to the control module at level i, where 0 < i ≤ N, and i is an integer. The control module at level i is configured to acquire a first power. When i is greater than 1, the first power is the power of the grid connection point at level i-1 reported by the control module at level i-1. When i equals 1, the first power is the power reported by the energy storage cabinet. The first power is summarized to obtain the second power of the grid connection point at level i. 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 at level i+1. The first target power of the grid connection point at level i is acquired. The second target power of the grid connection point at level i is determined based on the adjusted second power and the first target power, and then sent to the control module at level i-1 or the energy storage cabinet.

[0036] refer to Figure 2 The energy storage system in this embodiment also 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-reverse flow control protection.

[0037] pass Figure 1 , Figure 2 , Figure 3As can be seen, the N-level control modules of the energy management system in this embodiment form a multi-level relationship with the energy storage cabinet. The first-level control module is used to obtain the power reported by the energy storage cabinet. The first-level control module summarizes the power reported by the energy storage cabinet and then reports it to the second-level control module, and so on, reporting layer by layer to the Nth-level control module. The figure shows a three-level grid connection point structure. In practical applications, the grid connection point can be 1 level, 2 levels, 4 levels, etc.

[0038] In terms of hardware deployment, this embodiment only deploys one set of local EMS hardware in the control room of the energy storage system. The EMS hardware uses industrial-grade servers, industrial control computers or embedded devices to adapt to the scenario and data volume. It has multiple network ports and high computing power to meet the needs of multi-level data processing and instruction concurrency. The EMS hardware is connected to an industrial Ethernet switch and serves as the core hub for power control of multi-level grid connection points, uniformly collecting, processing and issuing data and instructions.

[0039] Specifically, the energy storage cabinet includes: an energy storage converter, a battery management system (BMS), a protocol converter, and at least one functional module. The energy management system connects to the energy storage converter, battery management system, and protocol converter via a switch. The protocol converter also connects to at least one functional module. Functional modules can include the fire suppression system, liquid cooling unit, temperature and humidity sensor, etc., within the energy storage cabinet. The energy storage converter and battery management system support Modbus-TCP protocol or other network protocols and are directly connected to the switch to communicate with the local EMS. Functional modules such as the fire suppression system, liquid cooling unit, and temperature and humidity sensor do not support network protocols and are connected after protocol conversion via a protocol converter (such as an RS485 to Ethernet converter), ensuring full connectivity of all devices in the underlying energy storage cabinet.

[0040] Specifically, each control module and each energy storage cabinet is equipped with corresponding identification information, such as ID (Identification), to distinguish the hierarchical relationship between multiple control modules. When reporting or sending the corresponding power, each module will carry its own ID information so that the corresponding control module or energy storage cabinet can identify the corresponding power and improve the accuracy of energy storage system control.

[0041] In traditional multi-EMS architectures, power control commands need to pass through the main EMS to the sub-EMS, and then to the converter PCS in the energy storage cabinet. This is a long-link transmission with high communication latency. Furthermore, the sub-EMS needs to parse the main command before forwarding it to the converter in the energy storage cabinet. Coupled with the time consumed by protocol conversion, this results in delayed response in scenarios with high real-time requirements such as anti-reverse current and demand control.

[0042] The energy storage system in this embodiment only has one energy management system, which not only enables control over the multi-level grid connection points of the energy storage system with low hardware cost; but also, the energy management system of the energy storage system is connected to the energy storage cabinet through a switch, eliminating the intermediate EMS node in the traditional solution. The instructions of the energy management system can directly reach the bottom energy storage cabinet, resulting in high coordination efficiency; furthermore, multiple virtual control modules are set in the energy management system, which can accurately capture power changes at the grid connection points and quickly complete the response, resulting in high power control adaptability.

[0043] Another embodiment of this application relates to a control method for an energy storage system, applied to the energy management system of the energy storage system, see reference. Figure 1 , Figure 2 , Figure 3 The energy management system is connected to at least one energy storage cabinet via a switch; the energy storage system includes N levels of grid connection points, where N is an integer greater than 0; the first level of grid connection points is connected to the energy storage cabinet; the energy management system includes N levels of control modules, where the i-th level of grid connection point corresponds to the i-th level of control module, 0 < i ≤ N, and i is an integer.

[0044] like Figure 4 The diagram shown is a flowchart illustrating the control method of the energy storage system in this embodiment. The control method of the energy storage system in this embodiment includes the following steps:

[0045] Step 101: The control module of the i-th level obtains the first power.

[0046] The execution entity in 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.

[0047] Specifically, when i is greater than 1, the first power P1 is the power of the grid connection point at level i-1 reported by the control module at level i-1; when i is equal to 1, the first power P1 is the power reported by the energy storage cabinet.

[0048] Step 102: Summarize the first power to obtain the second power of the grid connection point at the i-th level.

[0049] 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 summarizes the first power P1 reported by the control module at level (i-1) to obtain the second power P2 of the grid connection point at level i. When i equals 1, the grid connection point at level i is connected to the underlying energy storage cabinet. The energy storage cabinet reports its own first power P1 to the control module at level i. The control module at level i summarizes the first power P1 reported by the energy storage cabinet to obtain the second power P2 of the grid connection point at level i.

[0050] Step 103: Adjust the second power according to the preset rules to obtain the adjusted second power.

[0051] Specifically, when i is less than N, the control module at level i reports the adjusted second power P2 to the control module at level i+1 for aggregation. When i equals N, the highest-level control module, i.e., the control module at level N, directly calculates the second target power of the grid connection point or energy storage cabinet at level N-1 based on the second power P2.

[0052] In this embodiment, after the control module of the i-th level summarizes the first power P1 to obtain the second power P2 of the grid connection point of the i-th level, it adjusts the second power P2 according to preset rules, which can improve the accuracy of the second power P2 of the grid connection point of the i-th level. For example, when adjusting the second power P2, the control module of the i-th level can combine the control logic of demand control protection and anti-reverse current control protection. Demand control protection limits the maximum demand of users to prevent overload of equipment in the energy storage system, such as transformers and lines, and avoids equipment damage. Anti-reverse current control protection can prevent the grid voltage from rising and avoid damage to user equipment on the grid side. Thus, the adjustment of the second power P2 is achieved through demand control protection and anti-reverse current control protection, thereby ensuring the safety of the energy storage system operation.

[0053] like Figure 5 The diagram shown is a flowchart of each sub-step of step 103. Step 103 includes the following sub-steps:

[0054] Step 1031: The control module at level i obtains the charging and discharging state of the energy storage system based on the second power before adjustment.

[0055] Step 1032: When the energy storage system is in a charging state, execute charging protection control.

[0056] Step 1033: When the energy storage system is in a discharge state, execute discharge protection control.

[0057] In this embodiment, the second power P2 of the i-th level grid connection point can determine the charging and discharging state of the energy storage system. When the second power P2 is positive, the energy storage system is in the discharging state and discharge protection control is executed. When the second power P2 is negative, the energy storage system is in the charging state and charging protection control is executed. The corresponding protection control mode can be selected according to the charging and discharging state of the energy storage system to ensure the safety of the energy storage system during operation.

[0058] In this embodiment, the charging protection control can be demand control protection, and the discharging protection control can be reverse current prevention control protection. By implementing demand control protection and reverse current prevention control protection during the charging and discharging processes of the energy storage system, the safety of the energy storage system during operation is improved.

[0059] like Figure 6 The diagram shown illustrates the execution flow of charging protection control, which includes the following steps:

[0060] Step 10321: Determine whether the sum of the second power and the first load power is greater than the target required power.

[0061] If yes, proceed to step 10322, whereby the second power P2 is adjusted to the difference between the first load power and the target demand power; otherwise, proceed to step 10323, whereby the current second power P2 is maintained.

[0062] Step 10322: Adjust the second power to the difference between the first load power and the target demand power.

[0063] Step 10323: Maintain the current second power.

[0064] Specifically, the first load power P3 is the sum of the demand power of all grid-connected points in the i-th level other than the current i-th level grid-connected point, referencing... Figure 1 For a first-level grid connection point, the second power P2 is the sum of the first power P1 of all energy storage cabinets under that grid connection point, and the sum of the demand power of other first-level grid connection points at the same level as that grid connection point is the first load power P3; for a second-level grid connection point, the second power P2 is the sum of the first power P1 of all energy storage cabinets under that grid connection point, and the sum of the demand power of other second-level grid connection points at the same level as that grid connection point is the first load power P3.

[0065] Each grid connection point is equipped with a grid connection point meter, such as 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. The demand power of other grid connection points at the i-th level can be obtained through the smart meters and / or demand meters installed at other grid connection points at the i-th level. In this embodiment, the calculation of the first load power P3 requires the use of the real-time load demand monitored by the smart meters and / or demand meters. After the smart meters and / or demand meters detect the real-time load demand of other grid connection points at the i-th level, they report it to the energy management system. The energy management system can then calculate the sum of the real-time load demands of the other grid connection points at the i-th level, which is the first load power P3.

[0066] In this embodiment, the second power P2 is the charging power, which is generally represented as a negative number. Therefore, in this embodiment, calculating the sum of the second power P2 and the first load power P3 is actually calculating the sum of the absolute value of the second power P2 and the absolute value of the first load power P3. By calculating the sum of the second power P2 and the first load power P3, the total power of all grid-connected points at the i-th level 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 grid-connected points at the i-th level exceeds the target demand power P4. In this case, the second power P2 of the current grid-connected point at the i-th level needs to be 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 grid-connected points at the i-th level is kept 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 grid-connected points at the i-th level does not exceed the target demand power P4, and the current second power P2 is maintained.

[0067] Specifically, if the total power of the grid connection points at other i-th levels, i.e., the first load power P3, is less than the target demand power P4, then the second power P2 is adjusted to the difference between the first load power P3 and the target demand power P4. If the resulting second power P2 is still negative, it indicates that the second power P2 is still charging power, and the charging state of the second power P2 has not changed. The current adjusted second power P2 can be maintained. If the total power of the grid connection points at other i-th levels, i.e., the load power, is greater than the target demand power P4, then the second power P2 is adjusted to the difference between the first load power P3 and the target demand power P4. If the resulting second power P2 is positive after adjustment, it indicates that the second power P2 has changed to discharging power, and the second power P2 has changed from a charging state to a discharging state. Therefore, it is necessary to further determine whether to switch to a charging state according to the user's instructions in order to further adjust the second power P2.

[0068] 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. A positive adjusted second power P2 indicates that the second power P2 is the discharge power, and a negative adjusted second power P2 indicates that the second power P2 is the charging power.

[0069] Therefore, this embodiment, after step 10322, which adjusts the second power P2 to the difference between the first load power P3 and the target demand power P4, further includes:

[0070] Step 10324: Re-determine the charging and discharging state of the energy storage system based on the adjusted second power.

[0071] If the energy storage system is in a discharging state, proceed to step 10325; if the energy storage system is in a charging state, proceed to step 10329.

[0072] Step 10325: When the energy storage system is in a discharging state, determine whether to switch from a charging state to a discharging state according to the user's instruction.

[0073] If yes, proceed to step 10326 to execute discharge protection control; otherwise, proceed to step 10327 to adjust the second power P2 to 0.

[0074] Step 10326: Execute discharge protection control.

[0075] Step 10327: Adjust the second power to 0.

[0076] This embodiment, after step 10327, which adjusts the second power to 0, also includes the following steps:

[0077] Step 10328: The energy management system controls the energy storage cabinet connected to the grid connection point of level i to stop operating.

[0078] Step 10329: If the energy storage system is in a charging state, then maintain the current second power.

[0079] Specifically, when the adjusted second power P2 is detected as charging power, and the energy storage system is in a charging state, the current second power P2 is maintained. When the adjusted second power P2 is detected as discharging power, the user will be prompted whether to switch to discharging state. If the user issues a command to switch to discharging state, discharge protection control will be executed, i.e., steps 10331 to 10333 below will be executed. If the user does not instruct to switch to discharging state, in order to ensure the safety of the energy storage system, the second power P2 will be adjusted to 0, and all energy storage systems connected to the current grid connection point will stop operating.

[0080] like Figure 7 The diagram shown illustrates the execution flow of discharge protection control, which includes the following steps:

[0081] Step 10331: Determine whether the second power is greater than the difference between the second load power and the minimum grid power.

[0082] If yes, proceed to step 10332, whereby the second power is adjusted to the difference between the second load power and the minimum grid power; otherwise, proceed to step 10333, whereby the current second power is maintained.

[0083] Step 10332: The second power is adjusted to the difference between the second load power and the minimum grid power.

[0084] Step 10333: Maintain the current second power.

[0085] Specifically, the minimum grid-connected power P5 is a protection threshold set in the anti-reverse current control protection. When the power delivered by the grid to the load side (i.e., the "grid-connected power") is lower than or equal to the minimum grid-connected power, during the anti-reverse current control protection process, it will be determined that the power generation of the local energy storage system has approached or exceeded the load demand, thereby triggering the limiting of power generation or the disconnection of some power generation equipment, that is, limiting the power generation of the energy storage system to prevent reverse current. When the power delivered 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 at full capacity.

[0086] Specifically, the second load power P6 is the sum of the load powers of all other grid-connected points at the i-th level, excluding the current i-th level grid-connected point. In this embodiment, each grid-connected point is equipped with a grid-connected point meter, such as 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-connected point in real time. In this embodiment, the calculation of the second load power P6 requires the use of the real-time load power monitored by the smart meter and / or demand meter. After the smart meter and / or demand meter detects the real-time load power of other grid-connected 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 power of the other grid-connected points at the i-th level, which is the second load power P6.

[0087] In this embodiment, the second power P2 is the discharge power, which is generally represented as a positive number. The difference between the second load power P6 and the minimum grid power P5 obtained in this embodiment is the absolute value of the difference between the second load power P6 and the minimum grid power P5.

[0088] If the second power P2 is greater than the difference between the second load power P6 and the minimum grid disconnection power P5, it means that the sum of the second load power P6 and the second power P2 of the current i-th grid connection point exceeds the minimum grid disconnection power P5. This indicates that the total discharge power of the energy storage system exceeds the minimum grid disconnection power P5, and the power generation of the local energy storage system is close to or exceeds the load demand. It is necessary to trigger power limiting or disconnect some power generation equipment, that is, to limit the power generation of the energy storage system and prevent backflow. Therefore, the second power P2 is adjusted to the difference between the second load power P6 and the minimum grid disconnection power P5, so that the sum of the second load power P6 and the second power P2 of the current i-th grid connection point, that is, the total discharge power of the energy storage system, is within the range of the minimum grid disconnection power P5. If the second power P2 is less than or equal to the difference between the second load power P6 and the minimum grid connection power P5, it means that the sum of the second load power P6 and the second power P2 of the current i-th grid connection point does not exceed the minimum grid connection power P5. This means that the total discharge power of the energy storage system does not exceed the minimum grid connection 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.

[0089] Step 104: Obtain the first target power of the grid connection point at the i-th level.

[0090] Specifically, when i equals N, the first target power is the power of the energy storage system determined according to the peak-valley mode. In this embodiment, the charging and discharging state of the energy storage system can be determined based on the first target power. When the energy storage system is in a discharging state, the second power P2 is the dischargeable power; when the energy storage system is in a charging state, the second power P2 is the rechargeable power. The peak-valley mode is an economically optimized operation strategy for the energy storage system. Its core purpose is to control the energy storage system to charge during periods of low electricity prices and discharge during periods of high prices, thereby reducing the electricity cost of the energy storage system and increasing its profitability.

[0091] Specifically, when i is less than N, the first target power obtained by the control module at level i is the second target power issued by the control module at level i+1.

[0092] Step 105: Determine the second target power of the grid connection point or energy storage cabinet at level i-1 based on the adjusted second power and the first target power, and send it to the control module or energy storage cabinet at level i-1.

[0093] This embodiment calculates the second target power of the next-level grid connection point or energy storage cabinet based on the adjusted second power P2 and the first target power, for reference. Figure 1 The first-level grid connection points acquire the adjusted second power P2 and the first target power issued by the second-level grid connection points. The first-level grid connection points calculate the second target power of the energy storage cabinets and issue it to each energy storage cabinet. The second-level grid connection points acquire the adjusted second power P2 and the first target power issued by the third-level grid connection points. The second-level grid connection points calculate the second target power of the first-level grid connection points and issue it to each first-level grid connection point. This process is repeated until the highest-level grid connection point acquires 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 points and issues it to each second-level grid connection point.

[0094] like Figure 8 The diagram shown is a flowchart of each sub-step of step 105. Step 105 includes the following sub-steps:

[0095] Step 1051: The control module of the i-th level selects the smaller of the first target power and the second power as the specified power.

[0096] Step 1052: Determine the second target power based on the first power, the second power, and the specified power.

[0097] 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 grid connection point or peak-valley mode at the previous level 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 grid connection point or peak-valley mode at the previous level 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 grid connection point or peak-valley mode at the previous level. Therefore, the first target power is selected as the designated power P0 to ensure a lower electricity cost for the energy storage system. In other words, this embodiment balances the safety and electricity cost of the energy storage system by taking the smaller of the first target power and the second power P2.

[0098] like Figure 9 The diagram shown is a flowchart of each sub-step of step 1052. Step 1052 includes the following sub-steps:

[0099] Step 10521: Determine the weight of the grid connection point or energy storage cabinet of the (i-1)th level based on the first power and the second power.

[0100] Step 10522: Obtain the second target power of the grid connection point or energy storage cabinet at level i-1 based on the weight and specified power.

[0101] Specifically, the second target power is calculated using the following formula: P0×P1 / P2; where P0 is the specified power, P1 is the first power, and P2 is the second power.

[0102] Specifically, after the grid connection point or energy storage cabinet at level i-1 reports the first power P1, the grid connection points at level i aggregate the first power P1 to obtain the second power P2. The weight of each grid connection point or energy storage cabinet at level i-1 is obtained based on the proportion of each first power P1 to the second power P2. For example, the grid connection points at level i-1 obtain the first power P1 reported by the bottom-level energy storage cabinets and aggregate it to obtain the second power P2. The weight of each energy storage cabinet is obtained based on the ratio of its first power P1 to its second power P2. The second target power of each energy storage cabinet is obtained based on its weight and a specified power P0. The grid connection points at level i-1 obtain the first power P1 reported by the grid connection points at level i-1 and aggregate it to obtain the second power P2. The weight of each grid-connected point in the first level is obtained by calculating the ratio of its first power P1 to its second power P2. The second target power of each grid-connected point in the first level is then obtained based on its weight and a specified power P0. Similarly, the grid-connected point in the Nth level obtains the first power P1 reported by the grid-connected point in the (N-1)th level and summarizes it to obtain the second power P2. The weight of each grid-connected point in the (N-1)th level is obtained by calculating the ratio of its first power P1 to its second power P2. The second target power of each grid-connected point in the (N-1)th level is then obtained based on its weight and a specified power P0.

[0103] This embodiment sets up multi-layer virtual control modules in the energy management system of the energy storage system. Each layer of control modules corresponds to an actual grid connection point in the energy storage system. Each layer of control module is used to obtain the first power P1 reported by the next-level grid connection point or energy storage cabinet, summarize the first power P1 to obtain the second power P2 corresponding to the grid connection point at this level and adjust it. At the same time, it obtains the first target power corresponding to the grid connection point at this level, determines the second target power of the next-level grid connection point or energy storage cabinet based on the adjusted second power P2 and the first target power, and sends it to the control module or energy storage cabinet at the next level. Thus, the control of multi-level grid connection points of the energy storage system can be realized by setting up only one energy management system, with low hardware cost. At the same time, the energy management system of this embodiment 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 coordination efficiency. Furthermore, the energy management system of this embodiment sets up multiple virtual control modules, which can accurately capture power changes at the grid connection point and quickly complete the response, with high power control adaptability.

[0104] This embodiment reduces the number of local EMS hardware components in the energy storage system, lowering equipment procurement, installation, and maintenance costs. Hardware costs for multi-level grid-connected energy storage projects in industrial and commercial sectors can be reduced by 35%-45%, effectively alleviating hardware cost pressures. Simultaneously, this embodiment, through the collaboration of virtual logic layers and real control layers, adapts to the differentiated control requirements of multi-level grid-connected points in industrial and commercial sectors (e.g., transformer side, low-voltage side). Combined with power control strategies such as anti-reverse current control protection and demand control protection, the execution is more precise, improving power control accuracy at multi-level grid-connected points by over 35%. Furthermore, the single EMS hardware architecture reduces multi-device collaboration latency, improving strategy response speed by over 30%. The real-time performance and accuracy of power control at multi-level grid-connected points are significantly enhanced, ensuring the safe and efficient operation of the energy storage system.

[0105] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A control method for an energy storage system, characterized in that, An energy management system applied to an energy storage system, wherein the energy management system is connected to at least one energy storage cabinet via a switch; the energy storage system includes N levels of grid connection points, where N is an integer greater than 0; the first level of grid connection point is connected to the energy storage cabinet; the energy management system includes N levels of control modules, where the i-th level of grid connection point corresponds to the i-th level of control module, 0 < i ≤ N, and i is an integer; The control method for the energy storage system includes: The control module at level i acquires the first power; when i is greater than 1, the first power is the power of the grid connection point at level i-1 reported by the control module at level i-1; when i is equal to 1, the first power is the power reported by the energy storage cabinet. The first power is summarized to obtain the 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; 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. Obtain the 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-1)th level is determined based on the adjusted second power and the first target power, and then sent to the control module or the energy storage cabinet at the (i-1)th level. The step of 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 charging and discharging state of the energy storage system based on the second power before adjustment; When the energy storage system is in a charging state, charging protection control is executed; When the energy storage system is in a discharging state, discharge protection control is executed; The charging protection control is as follows: determine whether the sum of the second power and the first load power is greater than the target demand power; if yes, adjust the second power to the difference between the first load power and the target demand power; if no, maintain the current second power; The discharge protection control is as follows: determine whether the second power is greater than the difference between the second load power and the minimum grid disconnection power; if yes, adjust the second power to the difference between the second load power and the minimum grid disconnection power; if no, maintain the current second power.

2. The control method for the energy storage system according to claim 1, characterized in that, The first load power is the sum of the demand power of the grid-connected points at the i-th level other than the current i-th level grid-connected point; the second load power is the sum of the load power of the grid-connected points at the i-th level other than the current i-th level grid-connected point.

3. The control method for the energy storage system according to claim 1, 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: The charge and discharge state of the energy storage system is re-determined based on the adjusted second power. When the energy storage system is in a discharging state, it is determined whether to switch from a charging state to a discharging state according to the user's instruction; if yes, the discharge protection control is executed; if no, the second power is adjusted to 0. When the energy storage system is in a charging state, the current second power is maintained.

4. The control method for the energy storage system according to claim 3, characterized in that, The control method for the energy storage system also includes: After the second power is adjusted 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.

5. The control method for the energy storage system according to claim 1, characterized in that, When i equals N, the first target power is the power of the energy storage system determined according to the peak-valley pattern.

6. The control method for the energy storage system according to claim 1, characterized in that, When i is less than N, the first target power obtained 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.

7. The control method for the energy storage system according to claim 1, characterized in that, The step of determining the second target power of the grid connection point or the energy storage cabinet at the (i-1)th level based on the adjusted second power and the first target power includes: The control module at level i selects the smaller of the first target power and the second power as the specified power; The second target power is determined based on the first power, the second power, and the specified power.

8. The control method for the energy storage system according to claim 7, characterized in that, Determining the second target power based on the first power, the second power, and the specified power includes: The weight of the grid connection point or the energy storage cabinet at the (i-1)th level is determined based on the first power and the second power; the second target power of the grid connection point or the energy storage cabinet at the (i-1)th level is obtained based on the weight and the specified power.

9. The control method for the energy storage system according to claim 8, characterized in that, The second target power is calculated using the following formula: P0×P1 / P2; Wherein, P0 is the specified power, P1 is the first power, and P2 is the second power.

10. An energy storage system, characterized in that, include: Energy management system, switch, energy storage cabinet; The energy management system is connected to at least one of the energy storage cabinets through the switch; the energy storage system includes N levels of grid connection points, the first level of grid connection point is connected to the energy storage cabinet, the energy management system includes N levels of control modules, the i-th level of grid connection point corresponds to the i-th level of control module, 0 < i ≤ N, and i is an integer; The control module at level i is configured to acquire a first power; when i is greater than 1, the first power is the power of the grid connection point at level i-1 reported by the control module at level i-1; when i is equal to 1, the first power is the power reported by the energy storage cabinet; the first power is summarized to obtain a second power of the grid connection point at level i; 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 level i+1. 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-1)-th 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-1)-th level. The step of 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 charging and discharging state of the energy storage system according to the second power before adjustment; When the energy storage system is in a charging state, charging protection control is executed; when the energy storage system is in a discharging state, discharging protection control is executed. The charging protection control is as follows: determining whether the sum of the second power and the first load power is greater than the target demand power; if yes, adjusting the second power to the difference between the first load power and the target demand power; if no, maintaining the current second power. The discharging protection control is as follows: determining whether the second power is greater than the difference between the second load power and the minimum grid disconnection power; if yes, adjusting the second power to the difference between the second load power and the minimum grid disconnection power; if no, maintaining the current second power.

11. The energy storage system according to claim 10, 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 via the switch; the protocol converter is also connected to at least one of the functional modules.

12. The energy storage system according to claim 10, characterized in that, The energy storage system also includes a grid connection point meter installed 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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