An efficiency-optimized energy storage unit power distribution method

Abstract

The application discloses an energy storage unit power distribution method based on efficiency optimization, and relates to the technical field of energy storage systems, which comprises the following steps: receiving a scheduling instruction issued by an energy storage scheduling system through an energy management system; executing a corresponding power distribution scheme according to the type of the scheduling instruction; the power distribution scheme comprises a first distribution scheme corresponding to a discharge instruction, a second distribution scheme corresponding to a charging instruction, and a third distribution scheme corresponding to a zero-power instruction; executing the power distribution scheme in a preset fixed cycle; for the first distribution scheme and the second distribution scheme, each cycle is reordered based on the real-time state of charge of each energy storage unit, and the corresponding power distribution scheme is executed; for the third distribution scheme, the power of all energy storage units is directly adjusted to zero in each cycle. The scheme can realize the charging and discharging balance of the energy storage units, and avoid the power dead zone and overload risk under low scheduling power.

Description

Technical Field

[0001] This application relates to the field of energy storage system technology, and in particular to a power allocation method for energy storage units based on efficiency optimization. Background Technology

[0002] With the rapid development of renewable energy, energy storage systems play a crucial role in power dispatch and load balancing. Currently, energy storage systems are mainly divided into centralized energy storage and string energy storage. Centralized energy storage typically divides multiple energy storage units into battery stacks, which are centrally controlled by an energy management system. String energy storage, on the other hand, is usually divided into battery clusters, with cluster-level energy storage units controlled by a local controller and regulated by the energy management system. Faced with the increasing demand for power allocation strategies for energy storage units, existing solutions generally have shortcomings.

[0003] There are two main current power allocation methods: The first is allocation based on the rated power ratio of energy storage units. This method cannot effectively balance the State of Charge (SOC) when the charging and discharging consistency of energy storage units is poor. Furthermore, when the dispatch command exceeds the total rated power of all energy storage units, it may lead to a shared risk of overload among the energy storage units. The second method allocates power based on the SOC ratio of energy storage units. However, under low dispatch power conditions, the allocated power may be less than the actual power dead zone, causing energy storage units to be unable to perform power allocation. Moreover, when the SOC of energy storage units differs significantly, the allocation result often exceeds the rated power of the energy storage units. Therefore, these methods fail to fully consider the optimal power problem of energy storage units and multi-objective optimization, resulting in the inability to improve the overall operating efficiency of the energy storage system. Summary of the Invention

[0004] The purpose of this application is to provide a power allocation method for energy storage units based on efficiency optimization, which aims to solve the technical problems of uneven charging and discharging of energy storage units and low power execution efficiency caused by insufficient power allocation strategies in the prior art.

[0005] To achieve the above objectives, this application provides a power allocation method for energy storage units based on efficiency optimization, the power allocation method for energy storage units based on efficiency optimization comprising: The energy management system receives dispatch instructions from the energy storage dispatch system; the dispatch instructions include discharge instructions, charging instructions and zero-power instructions. The power allocation scheme is executed according to the type of the scheduling instruction; the power allocation scheme includes a first allocation scheme corresponding to the discharge instruction, a second allocation scheme corresponding to the charging instruction, and a third allocation scheme corresponding to the zero power instruction; The power allocation scheme is executed cyclically according to a preset fixed cycle. For the first and second allocation schemes, each cycle reorders the energy storage units based on their real-time updated state of charge and executes the corresponding power allocation scheme. For the third allocation scheme, each cycle directly adjusts the power of all energy storage units to zero.

[0006] In one embodiment, the first allocation scheme prioritizes power allocation according to the order of energy storage unit state of charge from high to low; the second allocation scheme prioritizes power allocation according to the order of energy storage unit state of charge from low to high.

[0007] In one embodiment, the first allocation scheme includes a first-step discharge allocation and a second-step discharge allocation, wherein the first-step discharge allocation includes: Based on the sorting results of the state of charge from high to low, the first level of power is assigned to each energy storage unit. The first level of power is the operating power value of the energy storage converter that corresponds to each energy storage unit. If the total power corresponding to the discharge command has been fully allocated, the current power allocation round ends; otherwise, the second step of discharge allocation begins.

[0008] In one embodiment, the value of the first power level is configured according to the model of the energy storage converter.

[0009] In one embodiment, the second step of discharge distribution includes: Keeping the energy storage units sorted by state of charge from high to low, continue to allocate the second power level to each energy storage unit one by one. The second power level is the supplementary power to the remaining dispatch power. The power allocation for this round of discharge ends when the total power corresponding to the discharge command has been fully allocated, or when the allocated power of all energy storage units has reached their respective rated power.

[0010] In one embodiment, the second allocation scheme includes a first step of charging allocation and a second step of charging allocation, wherein the first step of charging allocation includes: All energy storage units are sorted from low to high according to their state of charge, and negative first-level power is allocated to each energy storage unit according to the sorting result. If the total power corresponding to the charging command has been fully allocated, the current power allocation round ends; otherwise, proceed to the second step of charging allocation.

[0011] In one embodiment, the second step of charging distribution includes: Keeping the energy storage units sorted by state of charge from low to high, continue to allocate negative second-level power to each energy storage unit one by one; If the total power corresponding to the charging command is fully allocated, or if the allocated power of all energy storage units reaches their respective rated power, then the power allocation for this round of charging ends.

[0012] In one embodiment, the sum of the first power level and the second power level is less than or equal to the rated power of a single energy storage unit.

[0013] In one embodiment, the energy storage scheduling system includes a centralized energy storage system and a string energy storage system. If it is a centralized energy storage system, the energy management system directly applies the power allocation command to each energy storage unit. If it is a string energy storage system, the energy management system first sends the power allocation command to the cluster-level centralized controller, and then the cluster-level centralized controller forwards the power allocation command to the corresponding cluster-level energy storage unit.

[0014] In one embodiment, the allocated power of a single energy storage unit does not exceed the rated power, and the total power allocated to all energy storage units is consistent with the total power corresponding to the scheduling command.

[0015] The above-mentioned technical solution of this application has at least the following beneficial technical effects: The technical solution of this application adapts differentiated power allocation schemes according to the type of scheduling instruction, and combines fixed-cycle loops with dynamic sorting mechanisms based on real-time state of charge. This enables balanced charging and discharging of energy storage units, avoids power dead zones and overload risks under low scheduling power, fully adapts to the optimal power operation requirements of energy storage units, and helps improve power allocation execution efficiency and multi-objective optimization effects, thereby ensuring the overall operational stability of the energy storage system. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating an embodiment of the energy storage unit power allocation method based on efficiency optimization provided in this application; Figure 2 This is a flowchart illustrating a specific embodiment of the energy storage unit power allocation method based on efficiency optimization provided in this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0018] The embodiments described in this application are only some, not all, of the embodiments described herein. All other embodiments obtained by those skilled in the art based on the embodiments described herein without inventive effort are within the scope of protection of this application.

[0019] With the rapid development of renewable energy, energy storage systems play a crucial role in power dispatch and load balancing. Currently, energy storage systems are mainly divided into centralized energy storage and string energy storage. Centralized energy storage typically divides multiple energy storage units into battery stacks, which are centrally controlled by an energy management system. String energy storage, on the other hand, is usually divided into battery clusters, with cluster-level energy storage units controlled by a local controller and regulated by the energy management system. Faced with the increasing demand for power allocation strategies for energy storage units, existing solutions generally have shortcomings.

[0020] There are two main current power allocation methods: The first is allocation based on the rated power ratio of energy storage units. This method cannot effectively balance the State of Charge (SOC) when the charging and discharging consistency of energy storage units is poor. Furthermore, when the dispatch command exceeds the total rated power of all energy storage units, it may lead to a shared risk of overload among the energy storage units. The second method allocates power based on the SOC ratio of energy storage units. However, under low dispatch power conditions, the allocated power may be less than the actual power dead zone, causing energy storage units to be unable to perform power allocation. Moreover, when the SOC of energy storage units differs significantly, the allocation result often exceeds the rated power of the energy storage units. Therefore, these methods fail to fully consider the optimal power problem of energy storage units and multi-objective optimization, resulting in the inability to improve the overall operating efficiency of the energy storage system.

[0021] To address the aforementioned technical problems, this application provides a power allocation method for energy storage units based on efficiency optimization.

[0022] In one embodiment of this application, please refer to Figure 1 The energy storage unit power allocation method based on efficiency optimization includes the following steps: Step S1: Receive dispatch instructions from the energy storage dispatch system through the energy management system. The dispatch instructions include discharge instructions, charging instructions, and zero-power instructions. In this step S1, taking a centralized energy storage system with 10 energy storage units (each with a rated power of 2MW, corresponding to the optimal power point of the energy storage converter of 0.75Pn=1.5MW) as the object, the energy management system receives discharge instructions (positive value), charging instructions (negative value), or zero-power instructions from the energy storage dispatch system in real time. The sampling frequency is set to 10Hz to ensure the real-time and accurate reception of instructions. By accurately receiving dispatch requirements, the foundation is laid for subsequent differentiated power allocation, ensuring the effective implementation of dispatch instructions.

[0023] Step S2: Execute the corresponding power allocation scheme according to the type of scheduling instruction; the power allocation scheme includes a first allocation scheme corresponding to the discharge instruction, a second allocation scheme corresponding to the charging instruction, and a third allocation scheme corresponding to the zero-power instruction; in this step S2, the energy management system identifies the type of scheduling instruction: when receiving a positive discharge instruction, it adapts to the first allocation scheme; when receiving a negative charging instruction, it loads the second allocation scheme; and when receiving a zero-power instruction, it activates the third allocation scheme. Through precise matching of instruction type and allocation scheme, the power allocation under different scheduling needs becomes more targeted, taking into account both optimal efficiency and multi-objective optimization requirements.

[0024] Step S3: Execute the power allocation scheme cyclically according to a preset fixed period. For the first and second allocation schemes, each cycle reorders the energy storage units based on their real-time updated state of charge and executes the corresponding power allocation scheme. For the third allocation scheme, each cycle directly adjusts the power of all energy storage units to zero. In step S3, a preset fixed period of 1 minute is set to cyclically execute the adapted power allocation scheme. For the first and second allocation schemes, each cycle collects and reorders the real-time updated state of charge of each energy storage unit to ensure that the allocation strategy dynamically adapts to the unit state. The third allocation scheme directly adjusts the power of all units to zero in each cycle. Through periodic dynamic adjustment, the balance of the state of charge and the continuity of scheduling command execution are ensured, improving the long-term operational stability of the system.

[0025] Specifically, in the first allocation scheme, for a total discharge command of 20MW, the 10 energy storage units are first sorted according to their state of charge (SOC) from high to low, and then allocated in two steps: the first step allocates 1.5MW (0.75Pn), and the second step allocates 0.5MW (0.25Pn). The final total power allocated to all units matches the dispatch command and does not exceed the rated power. By prioritizing SOC and allocating in stages, optimal efficiency and SOC balance are considered, improving system conversion efficiency by more than 15%. In the second allocation scheme, for a total charging command of -18MW, the 10 energy storage units are first sorted according to their SOC from low to high, and then allocated in two steps: the first step allocates -1.5MW (-0.75Pn), and the second step allocates -0.5MW (-0.25Pn). The final total power allocated matches the charging command and does not exceed the rated power. By prioritizing allocation based on low SOC, charging efficiency and SOC balance are considered, preventing some units from prematurely losing their charging capacity. In this third allocation scheme, when a zero-power command is received, the energy management system directly issues a power zero-adjustment command to all energy storage units without collecting the state of charge and sorting. The command response time is ≤50ms. By quickly executing zero-power control, the system can be smoothly shut down when there is no scheduling requirement, avoiding ineffective energy consumption and ensuring the safety of equipment when it is idle.

[0026] In one embodiment, the first allocation scheme prioritizes power allocation according to the energy storage units' state of charge (SBC) from high to low; the second allocation scheme prioritizes power allocation according to the energy storage units' SBC from low to high. Specifically, in the first allocation scheme, for a total discharge command of 20MW, the 10 energy storage units are first sorted according to their SBC from high to low, and power is allocated sequentially. In the second allocation scheme, for a total charging command of -18MW, the 10 energy storage units are first sorted according to their SBC from low to high, and power is allocated sequentially.

[0027] In one embodiment, the first allocation scheme includes a first-step discharge allocation and a second-step discharge allocation. The first-step discharge allocation includes the following specific steps: Based on the state of charge (SBC) ranking from highest to lowest, a first-tier power is allocated to each energy storage unit. The first-tier power is the operating power value adapted to the energy storage converter corresponding to each energy storage unit. Specifically, the value of the first-tier power is configured according to the model of the energy storage converter. If the total power corresponding to the discharge command has been fully allocated, this round of power allocation ends; otherwise, the second-step discharge allocation begins. In this first-step discharge allocation, based on the SBC ranking from highest to lowest, a first-tier power of 1.5MW (adapting to the optimal efficiency point of the energy storage converter) is allocated to each energy storage unit sequentially. When a 20MW discharge command is allocated to the 10th unit, 5MW remains unallocated, and the second-step discharge allocation begins. By prioritizing the allocation of optimal power, as many units as possible operate in the high-efficiency range, improving the overall system conversion efficiency.

[0028] In one embodiment, the second step of discharge allocation includes: maintaining the energy storage units in descending order of state of charge, and continuing to allocate second-tier power to each energy storage unit one by one. The second-tier power is supplementary power to the remaining dispatched power. The current round of discharge power allocation ends when the total power corresponding to the discharge command has been fully allocated, or when the allocated power to all energy storage units reaches their respective rated power. In this second step of discharge allocation, maintaining the descending order of state of charge, 0.5MW of second-tier power (supplementary power) is allocated to each energy storage unit sequentially. After allocating 1MW to each of the first 5 units, the 20MW discharge command is fully allocated, and the current round of allocation ends. By supplementing the remaining power allocation, the dispatch command is ensured to be fully executed, while avoiding unit overload and ensuring equipment safety.

[0029] In one embodiment, the second allocation scheme includes a first-step charging allocation and a second-step charging allocation. The first-step charging allocation includes: sorting all energy storage units according to their state of charge from low to high, and allocating negative first-level power to each energy storage unit one by one according to the sorting result; if the total power corresponding to the charging command has been fully allocated, the current round of power allocation ends; otherwise, the second-step charging allocation begins. In this first-step charging allocation, each energy storage unit is sorted from low to high state of charge and allocated a negative first-level power of -1.5MW (adapting to the converter's optimal efficiency point) sequentially. When the -18MW charging command is allocated to the 10th unit, -3MW remains unallocated, and the second-step charging allocation begins. By prioritizing the allocation of optimal power to units with low state of charge, the state of charge balancing is accelerated, and the duration of available power in the system is improved.

[0030] In one embodiment, the second step of charging allocation includes: maintaining the energy storage units in ascending order of state of charge, and continuing to allocate negative second-level power to each energy storage unit sequentially; if the total power corresponding to the charging command is fully allocated, or the allocated power of all energy storage units reaches their respective rated power, then this round of charging power allocation ends. In this second step of charging allocation, maintaining the ascending order of state of charge, and continuing to allocate -0.5MW of negative second-level power to each energy storage unit sequentially, after allocating -0.5MW to each of the first 6 units, the -18MW charging command is fully allocated, and this round of allocation ends. By supplementing the allocation of remaining charging power, the scheduling command is fully executed, while avoiding unit overload and ensuring the safety and efficiency of the charging process.

[0031] In one embodiment, the sum of the first-level power and the second-level power is less than or equal to the rated power of a single energy storage unit. In this embodiment, taking an energy storage unit with a rated power of 2MW as an example, the first-level power is set to 1.5MW (0.75Pn), and the second-level power is set to 0.5MW (0.25Pn). The sum of these two is exactly equal to the rated power of a single energy storage unit of 2MW. During charging, the sum of the corresponding negative-level power also matches the absolute value of the rated power. By clearly defining the matching relationship between the two-level power and the rated power, it ensures that the power of a single unit does not exceed the rated value during the allocation process, avoiding the risk of overload operation, while also ensuring the rationality and standardization of power allocation.

[0032] In one embodiment, the energy storage dispatch system includes a centralized energy storage system and a string energy storage system. For a centralized energy storage system, the energy management system directly extends the power allocation command to each energy storage unit. For a string energy storage system, the energy management system first sends the power allocation command to the cluster-level centralized controller, which then forwards the command to the corresponding cluster-level energy storage units. In this embodiment, for the centralized energy storage system, the energy management system directly extends the allocated power command (e.g., 1.5MW or 0.5MW discharge power per unit) to 10 energy storage units. The command transmission delay is ≤20ms. By directly sending the command, intermediate steps are reduced, command execution efficiency is improved, and power allocation is ensured to be implemented quickly, adapting to scenarios with high response speed requirements, such as frequency regulation services.

[0033] In one embodiment, the allocated power of a single energy storage unit does not exceed its rated power, and the total power allocated to all energy storage units is consistent with the total power corresponding to the dispatch command. In this embodiment, for string energy storage systems, the energy management system first sends the allocated power command to three cluster-level centralized controllers (each cluster contains 3-4 energy storage units), and then the controllers forward it to the corresponding cluster-level units. The forwarding delay is ≤30ms. By hierarchically sending commands to adapt to the characteristics of the string structure, the power allocation under different system types can be accurately executed, improving the versatility of the method.

[0034] In one specific embodiment, please refer to Figure 2 Taking an energy storage system (supporting centralized or string type) containing multiple energy storage units (rated power may vary, the optimal efficiency point of the energy storage converter is 0.75Pn_i, 0.75 can be flexibly configured according to the converter model) as the object, the energy storage dispatch system stipulates that the discharge command is a positive value, the charging command is a negative value, and the zero power command is 0. The power allocation process is as follows: The energy management system first receives the Pcommand (total power of the dispatch command) issued by the energy storage dispatch system, initializes Pleft (remaining unallocated power) = Pcommand, and then determines the type of Pcommand: If it is a discharge command (Pcommand>0): First, sort all energy storage units from highest to lowest state of charge, and allocate the first power level of 0.75Pn_i to each unit in turn. For each unit allocated, Pleft=Pleft-0.75Pn_i is updated synchronously. If Pleft≤0, the allocation ends in this round; if Pleft>0, proceed to the second step, keep the original sorting unchanged, and continue to allocate the second power level of 0.25Pn_i to each unit, and update Pleft=Pleft-0.25Pn_i synchronously, until Pleft=0 or all units reach the rated power (0.75Pn_i+0.25Pn_i=Pn_i). In a centralized system, the command is directly issued to the unit, and in a string system, it is forwarded through the cluster-level controller.

[0035] If it is a charging command (Pcommand<0): First, sort all energy storage units according to their state of charge from low to high, and allocate -0.75Pn_i of negative first-level power to each unit in turn. For each unit allocated, Pleft=Pleft-(-0.75Pn_i) is updated synchronously. If Pleft≥0, the allocation round ends; if Pleft<0, proceed to the second step, keep the original sorting unchanged, and continue to allocate -0.25Pn_i of negative second-level power to each unit, and update Pleft=Pleft-(-0.25Pn_i) synchronously until Pleft=0 or the power of all units reaches the absolute value of the rated power.

[0036] If it is a zero power command (Pcommand=0): the power zeroing command is directly issued to all energy storage units without sorting or tiering, and the process ends.

[0037] The entire process is executed in a fixed cycle. The discharge and charging conditions are reordered based on the real-time updated state of charge of each energy storage unit in each round. Pleft real-time tracking ensures that Pcommand is executed accurately, while the energy storage converter operates in the optimal efficiency range as much as possible, taking into account the balance of state of charge and equipment safety, and avoiding overload and power dead zone problems.

[0038] This application aims to protect a power allocation method for energy storage units based on efficiency optimization. The technical solution of this application adapts differentiated power allocation schemes according to the type of scheduling instruction, and combines fixed-cycle loops with dynamic sorting mechanisms based on real-time state of charge. This enables balanced charging and discharging of energy storage units, avoids power dead zones and overload risks under low scheduling power, fully adapts to the optimal power operation requirements of energy storage units, and is conducive to improving the efficiency of power allocation execution and multi-objective optimization effect, thus ensuring the overall operational stability of the energy storage system.

[0039] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this application and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this application should be included within the protection scope of this application. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A power allocation method for energy storage units based on efficiency optimization, characterized in that, include: The energy management system receives dispatch instructions from the energy storage dispatch system; the dispatch instructions include discharge instructions, charging instructions and zero-power instructions. The power allocation scheme is executed according to the type of the scheduling instruction; the power allocation scheme includes a first allocation scheme corresponding to the discharge instruction, a second allocation scheme corresponding to the charging instruction, and a third allocation scheme corresponding to the zero power instruction; The power allocation scheme is executed cyclically according to a preset fixed period; For the first and second allocation schemes, each round of the cycle reorders the energy storage units based on their real-time updated state of charge and executes the corresponding power allocation scheme; for the third allocation scheme, each round of the cycle directly adjusts the power of all energy storage units to zero.

2. The energy storage unit power allocation method based on efficiency optimization according to claim 1, characterized in that, The first allocation scheme prioritizes power allocation based on the energy storage units' state of charge from high to low; the second allocation scheme prioritizes power allocation based on the energy storage units' state of charge from low to high.

3. The energy storage unit power allocation method based on efficiency optimization according to claim 2, characterized in that, The first allocation scheme includes a first-step discharge allocation and a second-step discharge allocation, wherein the first-step discharge allocation includes: Based on the sorting results of the state of charge from high to low, the first level of power is assigned to each energy storage unit. The first level of power is the operating power value of the energy storage converter that corresponds to each energy storage unit. If the total power corresponding to the discharge command has been fully allocated, the current power allocation round ends; otherwise, the second step of discharge allocation begins.

4. The energy storage unit power allocation method based on efficiency optimization according to claim 3, characterized in that, The value of the first power level is configured according to the model of the energy storage converter.

5. The energy storage unit power allocation method based on efficiency optimization according to claim 3, characterized in that, The second step of discharge distribution includes: Keeping the energy storage units sorted by state of charge from high to low, continue to allocate the second power level to each energy storage unit one by one. The second power level is the supplementary power to the remaining dispatch power. The power allocation for this round of discharge ends when the total power corresponding to the discharge command has been fully allocated, or when the allocated power of all energy storage units has reached their respective rated power.

6. The energy storage unit power allocation method based on efficiency optimization according to claim 5, characterized in that, The second allocation scheme includes a first step of charging allocation and a second step of charging allocation. The first step of charging allocation includes: All energy storage units are sorted from low to high according to their state of charge, and negative first-level power is allocated to each energy storage unit according to the sorting result. If the total power corresponding to the charging command has been fully allocated, the current power allocation round ends; otherwise, proceed to the second step of charging allocation.

7. The energy storage unit power allocation method based on efficiency optimization according to claim 6, characterized in that, The second step of charging distribution includes: Keeping the energy storage units sorted by state of charge from low to high, continue to allocate negative second-level power to each energy storage unit one by one; If the total power corresponding to the charging command is fully allocated, or if the allocated power of all energy storage units reaches their respective rated power, then the power allocation for this round of charging ends.

8. The energy storage unit power allocation method based on efficiency optimization according to claim 7, characterized in that, The sum of the first power level and the second power level is less than or equal to the rated power of a single energy storage unit.

9. The energy storage unit power allocation method based on efficiency optimization according to any one of claims 1 to 8, characterized in that, The energy storage scheduling system includes centralized energy storage systems and string energy storage systems. If it is a centralized energy storage system, the energy management system directly applies the power allocation command to each energy storage unit. If it is a string energy storage system, the energy management system first sends the power allocation command to the cluster-level centralized controller, and then the cluster-level centralized controller forwards the power allocation command to the corresponding cluster-level energy storage unit.

10. The energy storage unit power allocation method based on efficiency optimization according to any one of claims 1 to 8, characterized in that, The allocated power of a single energy storage unit shall not exceed the rated power, and the total power allocated to all energy storage units shall be consistent with the total power corresponding to the dispatch command.

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