Power distribution method, energy management system and storage medium

Abstract

The invention belongs to the technical field of energy storage systems, and relates to a power distribution method, an energy management system and a storage medium. When a system state is a charging state or a discharging state, the power of each battery pack is adjusted according to an equilibrium charge state distribution strategy when it is judged that the total power of the system meets a second power constraint condition and meets a first power constraint condition; when the total power of the system does not meet the second power constraint condition but meets the first power constraint condition, a maximum allowable power limit value amplification strategy is adopted, and the power potential is fully released and does not exceed the safety range; when the first power constraint condition is not met, an equal-current distribution strategy is adopted, single-pack overcurrent is avoided, the stability and safety of the system are improved, and the service life of the battery cell is prolonged. In addition, when the system state is an idle state, a maximum allowable power proportion distribution strategy is selected to carry out power distribution. On the basis, balance between the battery packs and system power output are considered, and the use performance and the operation stability of the energy storage system are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage systems, and particularly relates to a power distribution method, an energy management system and a storage medium. BACKGROUND

[0002] With the continuous expansion of the scale of energy storage systems, battery pack parallel expansion has become an important way to improve the system capacity and power capability. Common solutions include direct parallel connection at the battery end and parallel connection after voltage conversion through a bidirectional DC-DC converter. Direct parallel connection at the battery end is prone to circulating current in actual operation, especially low-temperature circulating current charging under low-temperature conditions, which may cause accelerated degradation of battery life. In contrast, battery packs equipped with bidirectional DC-DC converters gradually become the mainstream of application due to their voltage compatibility and operational independence.

[0003] In the implementation of the present application, the inventors have found that the existing energy storage system equipped with a bidirectional DC-DC converter still has deficiencies in power distribution. The existing method is mostly based on battery pack charging and discharging limits for distribution, and stops working after some battery packs are fully charged or discharged, which causes insufficient consideration of the balance of battery packs during operation, and the overall power capability of the system is reduced, which may result in excessive time consumption at the end of charging or premature loss of load-carrying capacity during discharging. Therefore, the existing power distribution method cannot simultaneously consider the balance between battery packs and system power output, which affects the performance and stability of the energy storage system. SUMMARY

[0004] To solve the above problems, the embodiments of the present application provide a power distribution method that takes into account the balance between battery packs and system power output, and improves the performance and stability of the energy storage system.

[0005] To solve the above technical problems, one technical solution adopted by the embodiments of the present application is to provide a power distribution method applied to an energy storage system, the method comprising: obtaining a system total power of the energy storage system; obtaining a system state of the energy storage system according to the system total power; selecting a first power distribution strategy when the system state is an idle state; selecting a second power distribution strategy when the system state is a charging state or a discharging state and the system total power does not satisfy a first power constraint condition; and selecting a third power distribution strategy when the system state is the charging state or the discharging state and the system total power satisfies the first power constraint condition, and the system total power satisfies a second power constraint condition.

[0006] In some embodiments, when the system state is an idle state, the first power distribution strategy is selected, comprising: when the system state is an idle state, selecting a maximum allowed power ratio distribution strategy as the first power distribution strategy.

[0007] In some embodiments, when the system state is the charging state or the discharging state, and the system total power does not satisfy the first power constraint condition, a second power distribution strategy is selected, including: when the system state is the charging state or the discharging state, judging whether the system total power satisfies the first power constraint condition; if the system total power does not satisfy the first power constraint condition, selecting an equal current distribution strategy as the second power distribution strategy; wherein the first power constraint condition is that the system total power is not greater than the total power limit value of the overcurrent point.

[0008] In some embodiments, when the system state is the charging state or the discharging state, and the system total power satisfies the first power constraint condition, if the system total power satisfies a second power constraint condition, a third power distribution strategy is selected, including: when the system state is the charging state or the discharging state, if the system total power satisfies the first power constraint condition; judging whether the system total power satisfies the second power constraint condition; if the system total power satisfies the second power constraint condition, selecting a balanced state of charge distribution strategy as the third power distribution strategy; wherein the second power constraint condition is that the system total power is not greater than the maximum allowed total power limit value of the energy storage battery pack.

[0009] In some embodiments, the method further includes: if the system total power does not satisfy the second power constraint condition; updating the maximum allowed power limit value of each battery pack in the energy storage battery pack through a maximum allowed power limit value amplification strategy; and selecting the balanced state of charge distribution strategy as the third power distribution strategy based on the maximum allowed power limit value.

[0010] In some embodiments, selecting the balanced state of charge distribution strategy as the third power distribution strategy includes: setting a target state of charge value of the energy storage battery pack; calculating a state of charge difference value of each battery pack in the energy storage battery pack according to the target state of charge value; initializing the allocated power of each battery pack and the power distribution state of each battery pack; executing a loop process for each battery pack until a first preset condition is satisfied, the loop process including: executing a power distribution process for each battery pack until a second preset condition is satisfied, the power distribution process including: distributing power to each battery pack based on the state of charge difference value, the allocated power, and the system total power, and updating the allocated power; judging the allocated power and the maximum allowed power limit value; if the allocated power is less than the maximum allowed power limit value, setting the power distribution state to an incomplete state; if the allocated power is not less than the maximum allowed power limit value, taking the maximum allowed power limit value as the allocated power; calculating the overflow power of each battery pack and setting the power distribution state to a completed state; calculating the total overflow power of the energy storage battery pack according to the overflow power; and when the total overflow power and the power distribution state of each battery pack do not satisfy the first preset condition, taking the total overflow power as the system total power and executing the power distribution process for each battery pack.

[0011] In some embodiments, the power distribution to each battery pack, the updating of the distributed power based on the state of charge difference, the distributed power and the total system power comprises: calculating a total state of charge difference of the energy storage battery pack according to the state of charge difference; calculating a power increment of each battery pack according to the state of charge difference, the total state of charge difference and the total system power; and updating the distributed power according to the power increment and the distributed power.

[0012] In some embodiments, the updating of the maximum allowable power limit of each battery pack in the energy storage battery pack by the maximum allowable power limit amplification strategy comprises: obtaining the maximum allowable power limit of each battery pack in the energy storage battery pack; obtaining an overcurrent point power limit of each battery pack; calculating a total maximum allowable power limit of the energy storage battery pack according to the maximum allowable power limit of each battery pack; calculating a target amplification power according to the total system power and the total maximum allowable power limit; calculating a maximum allowable power difference of each battery pack according to the overcurrent point power limit and the maximum allowable power limit; and updating the maximum allowable power limit of each battery pack according to the maximum allowable power difference, the target amplification power and the maximum allowable power limit.

[0013] To solve the above technical problems, another technical scheme adopted by the embodiments of the present application is to provide an energy management system, comprising: at least one processor; and a memory in communication connection with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the above method.

[0014] To solve the above technical problems, still another technical scheme adopted by the embodiments of the present application is to provide a non-volatile computer readable storage medium, which stores computer executable instructions, and when the computer executable instructions are executed by an energy management system, the energy management system performs the above method.

[0015] Different from the related art, the application provides a power distribution method, an energy management system and a storage medium. When the system state is a charging or discharging state, the application judges whether the total system power meets the second power constraint condition and the first power constraint condition, and adjusts the power of each battery pack according to the equal state of charge distribution strategy when the total system power meets the second power constraint condition and the first power constraint condition, so that the SOC tends to be consistent, and the power balance and the system load capacity are improved; when the total system power does not meet the second power constraint condition but meets the first power constraint condition, the maximum allowable power limit amplification strategy is adopted to fully release the power potential and not exceed the safety range; when the first power constraint condition is not met, the equal current distribution strategy is adopted to avoid single pack overcurrent, and the system stability, safety and cell life are improved. In addition, when the system state is an idle state, the maximum allowable power proportional distribution strategy is selected for power distribution. Based on this, the balance between the battery packs and the system power output is considered, and the use performance and operation stability of the energy storage system are improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are schematic and not intended to be limiting of the embodiments, and in which like reference numerals designate similar items in the figures. The figures are not necessarily to scale, the emphasis instead being placed upon illustrating the principles of the embodiments.

[0017] Figure 1 is a flowchart of a power distribution method provided by an embodiment of the application; Figure 2 is a flowchart of an equal state of charge distribution strategy provided by an embodiment of the application; Figure 3 is a hardware structure schematic diagram of an energy management system for executing the power distribution method provided by an embodiment of the application. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described below in detail with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the application. It should be understood that the specific embodiments described herein are only used to explain the application and should not be used to limit the application. It should be noted that, if not in conflict, the various features in the embodiments of the application can be combined with each other, and all within the protection scope of the application.

[0019] The terms "first", "second", and the like in the description and in the claims of the present application are used for distinguishing between similar objects and are not necessarily used to describe a particular sequential or chronological order. It is to be understood that the use of such terms is only made to distinguish between objects fulfilling comparable or similar functions to facilitate describing the present application and are not to be construed as limiting of a specific order or chronology of events as such can occur sequentially or can be performed concurrently or can be performed in any order.

[0020] Unless otherwise defined, all technical and scientific terms used in the present specification are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0021] Please refer to Figure 1 , Figure 1 is a flow chart of a power distribution method provided by an embodiment of the present application. As shown in Figure 1 , the method is applied to an energy management system of an energy storage system, and includes steps S1-S5: S1: Obtain the system total power of the energy storage system.

[0022] Obtain the real-time operating parameters of each battery pack from the battery management system (BMS) of each battery pack, including: the state of charge (SOC) of the battery pack, which is used to represent the percentage of the remaining capacity of the battery relative to the rated capacity; the maximum allowable power (SOP) limit of the battery pack, which is used to represent the available charging and discharging power capability of the battery under the current state, which is affected by factors such as SOC, state of health (SOH), temperature, and internal resistance; the battery pack terminal voltage U; the battery pack terminal current I; and the state flag information of the battery pack (such as fault flag, offline flag).

[0023] Based on the battery pack terminal voltage and the battery pack terminal current, the instantaneous power of each battery pack is calculated according to the formula , where the instantaneous power refers to the instantaneous power absorbed by the battery from the outside when charging >0); or the instantaneous power released by the battery to the outside when discharging <0>.

[0024] The instantaneous powers of all battery packs in the online state are accumulated to obtain the system total power of the current energy storage system: ; where N is the number of battery packs currently in the online state. ​

[0025] In the calculation process, further comprising: filtering the collected voltage and current data to eliminate transient noise; when detecting battery pack data anomaly or communication interruption, marking the battery pack as unusable and excluding the data of the battery pack in the total power calculation.

[0026] The total system power and the SOC and SOP limits of each battery pack are output to the energy management system (EMS) as the basis for subsequent power allocation and scheduling control.

[0027] S2: According to the system total power, the system state of the energy storage system is obtained.

[0028] To avoid misjudgment caused by transient fluctuations, a power determination threshold is set in advance , which is determined according to the number of battery packs, sampling accuracy and system noise level, and is used to define the range of "close to zero".

[0029] Based on the system total power and the power determination threshold , the system state of the energy storage system is determined, specifically including: When , it is determined that the system is in charging state, i.e. the system as a whole is in the process of absorbing external energy; When , it is determined that the system is in discharging state, i.e. the system as a whole releases energy to the outside; When , it is determined that the system is in idle state, i.e. the system as a whole does not have significant energy exchange.

[0030] The system state is output as a running flag signal for guiding the selection of subsequent power allocation strategy.

[0031] S3: When the system state is idle, select the first power allocation strategy.

[0032] When the system state is idle, select the maximum allowed power proportion allocation strategy as the first power allocation strategy.

[0033] When the system state is idle based on the system total power obtained in step S1, the following power allocation process is performed: When the system is in idle state, it means that the charging or discharging process has not been performed, at this time the initial power allocation strategy needs to be set according to the running mode (charging or discharging) to be performed. If not set reasonably, it may cause overcurrent of individual battery packs, expansion of SOC difference or system efficiency reduction.

[0034] When the energy storage system is operated in combination with a grid-side energy storage converter (PCS), the PCS issues a total charging power instruction or a total discharging power instruction, and ensures that the instruction does not exceed the maximum allowed power total limit value (SOP total limit value) of the energy storage battery pack reported by the system, that is, the SOP limit value of total charging or total discharging.

[0035] In this scenario, the first power distribution strategy is an SOP proportional distribution strategy (maximum allowed power proportional distribution strategy): if the PCS issues a total charging power instruction, the power is distributed according to the charging SOP proportion of each battery pack; if the PCS issues a total discharging power instruction, the power is distributed according to the discharging SOP proportion of each battery pack. The distribution proportion calculation formula is as follows: ; wherein, is the SOP limit value of the i-th battery pack, is the SOP total limit value of the energy storage battery pack.

[0036] For example, when the PCS issues a total charging power instruction, if the SOP limit value of battery pack A is 20 kW and the SOP limit value of battery pack B is 40 kW, the SOP total limit value of the energy storage battery pack is 60 kW, and when the total charging power instruction issued by the PCS requires a system total power of 30 kW, the system distributes the power according to the SOP proportion, and the distribution power of battery pack A is 10 kW and the distribution power of battery pack B is 20 kW.

[0037] In this embodiment, when the system state of the energy storage system is determined to be an idle state, the first power distribution strategy is executed to reasonably plan the output or energy absorption of each battery pack before charging and discharging starts, thereby effectively avoiding damage of individual battery packs due to overcurrent or uneven current distribution, and suppressing the expansion of SOC difference. When used in combination with a grid-side energy storage converter (PCS), the power is distributed according to the charging or discharging SOP proportion of each battery pack, which can fully utilize the available power capacity of each battery pack, ensure that the system total power does not exceed the SOP total limit value, and realize safe and efficient power output.

[0038] S4: When the system state is in a charging state or a discharging state, and the system total power does not satisfy the first power constraint condition, a second power distribution strategy is selected.

[0039] ​​​When the system state is the charging state or the discharging state and the total system power does not satisfy the first power constraint condition, a second power distribution strategy is selected, including: when the system state is the charging state or the discharging state, judging whether the total system power satisfies the first power constraint condition; if the total system power does not satisfy the first power constraint condition, selecting an equal current distribution strategy as the second power distribution strategy; wherein the first power constraint condition is that the total system power is not greater than the total power limit value at the overcurrent point.

[0040] When the system state is determined to be in the charging state or the discharging state, it is further necessary to check whether the current power of the system has an overcurrent risk. Specifically, first, the battery voltage U of each battery pack and its overcurrent protection set current value I are obtained , and the overcurrent point power limit value of each battery pack is calculated by the following formula : ; wherein, represents the maximum power threshold that the battery pack can safely withstand at the current voltage. Based on the overcurrent point power limit values of all battery packs, the total overcurrent point power limit value of the system is accumulated, that is, the upper limit of the total power that the system can safely withstand under the current conditions.

[0041] Subsequently, the total system power is compared with the total overcurrent point power limit value: If the total system power is not greater than the total overcurrent point power limit value, it indicates that the system as a whole is running within a safe range, and the power distribution strategy of step S5 can be executed without triggering the overcurrent protection; If the total system power is greater than the total overcurrent point power limit value, it indicates that the current total power has exceeded the overcurrent safety capability of part of the battery packs, at which time the distribution strategy needs to be adjusted. The equal current distribution strategy (second power distribution strategy) can be used to make each battery pack bear the same current on the battery side, so as to ensure that all battery packs approach the overcurrent point at the same time, thereby avoiding that individual battery packs trigger higher level overcurrent protection in advance.

[0042] The equal current distribution strategy, the basic principle of which is: according to the power formula , when the currents of the battery packs are controlled to be the same, that is, the same target current is set, the instantaneous power of each battery pack is proportional to its terminal voltage . It can be understood that the voltage ratio of each battery pack is the power distribution ratio, and the distribution ratio calculation formula is as follows: wherein, is the battery voltage of the i-th battery pack.

[0043] ​In this way, the same current can be guaranteed for all battery packs on the battery side, thereby avoiding triggering the overcurrent point due to excessive current borne by individual battery packs caused by voltage differences.

[0044] For example, assume that the system has three battery packs A, B, and C. The voltages are 300 V, 310 V, 290 V, and the target current is set to 10 A, then the power of each battery pack is: , the total power of the system is 9000 W. Among them, the power proportion of each battery pack is 33.3%, 34.4%, and 32.2% respectively. As can be seen, the battery pack with a higher voltage bears more power, and the battery pack with a lower voltage bears less power, and the current of all battery packs is consistent, thereby avoiding the risk of overcurrent.

[0045] In this embodiment, by comparing the total power of the system with the total power limit of the overcurrent point when the system is in the charging state or the discharging state, the potential overcurrent risk can be identified in the power distribution link in advance. When the total power of the system exceeds the total power limit of the overcurrent point, the equal-current distribution strategy is triggered in time, so that the current borne by each battery pack on the battery side remains consistent, thereby ensuring that each battery pack reaches the same protection level when approaching the overcurrent point, and avoiding the problem that individual battery packs trigger high-level overcurrent protection in advance, resulting in a sudden drop in the power of the entire system or disconnection. In this way, not only can the safety hazards caused by single-pack overload be effectively avoided, but also the power output stability and overcurrent resistance of the entire energy storage system can be improved, thereby prolonging the service life of the battery pack and enhancing the operation reliability of the system under complex working conditions.

[0046] Another situation is that when the system is in blind charging or directly running with a load, since the SOP intelligent management based on the real-time state of the battery is lost, the external power demand may not be constrained by the SOP total limit, and the system may attempt to extract (or pour) power exceeding the SOP total limit from one or more battery packs. Therefore, the equal-current distribution strategy (second power distribution strategy) can also be used to make each battery pack bear the same current on the battery side, thereby ensuring that all battery packs approach the overcurrent point at the same time, and avoiding individual battery packs triggering higher-level overcurrent protection in advance.

[0047] In the scenario of blind charging or direct drive of load, the equal current distribution strategy is adopted to keep the current of each battery pack consistent, and through current balancing control, some battery packs are avoided from bearing excessive power due to voltage difference, thereby reducing the risk of triggering overcurrent point. Through reasonable initial power distribution, not only the safe operation of each battery pack in the initial charging and discharging stage is ensured, and the system stability is improved, but also a reliable foundation is provided for subsequent dynamic power scheduling and SOC balancing, thereby improving the charging and discharging efficiency of the entire energy storage system, prolonging the battery life and ensuring the safe operation of the system.

[0048] S5: When the system state is in the charging state or the discharging state, and the total system power satisfies the first power constraint condition, if the total system power satisfies the second power constraint condition, a third power distribution strategy is selected.

[0049] When the system state is in the charging state or the discharging state, and the total system power satisfies the first power constraint condition, if the total system power satisfies the second power constraint condition, a third power distribution strategy is selected, including: when the system state is in the charging state or the discharging state, if the total system power satisfies the first power constraint condition; determining whether the total system power satisfies the second power constraint condition; if the total system power satisfies the second power constraint condition, selecting an equal state of charge distribution strategy as the third power distribution strategy; wherein the second power constraint condition is that the total system power is not greater than the maximum allowed total power limit value of the energy storage battery pack.

[0050] When the system state is in the charging state or the discharging state, and the total system power satisfies the first power constraint condition (the total system power is not greater than the total power limit value of the overcurrent point), it is determined whether the total system power satisfies the second power constraint condition (the total system power is not greater than the maximum allowed total power limit value of the energy storage battery pack (SOP total limit value)). It can be understood that when the total system power satisfies the first power constraint condition and the second power constraint condition at the same time, not only can it be ensured that the current will not exceed the current safety boundary of the battery or the device, avoiding the risk of overcurrent, but also it can be ensured that the battery can safely and continuously output / absorb the maximum power in the current state. At this time, the system is allowed to use the equal state of charge distribution strategy (equal SOC distribution strategy) to optimize the consistency of the energy storage battery pack.

[0051] Please refer to Figure 2 , Figure 2 is a flowchart of an equal state of charge distribution strategy provided by an embodiment of the present application. As shown in Figure 2 , selecting an equal state of charge distribution strategy as a third power distribution strategy includes steps S51-S54: S51: Setting a target state of charge value of the energy storage battery pack.

[0052] S52: Calculating the state of charge difference value of each battery pack in the energy storage battery pack according to the target state of charge value.

[0053] S53: Initialize the allocated power and power allocation status of each battery pack.

[0054] First, set a target state of charge value that all battery packs should eventually approach. For example: setting during charging ; Setting during discharge .

[0055] Secondly, according to The state-of-charge difference of each battery pack can be calculated.

[0056] Assume the energy storage battery pack contains N battery packs, and let the first one be the Nth battery pack. One battery pack is When the system is in a charging state, the first... State of charge difference of individual battery packs When in a discharge state, .in, For the first The current state of charge (SOC) value of each battery pack. This is understandable. Reflecting the How much charge is a battery pack still away from its target state of charge? The battery pack that is further away should be allocated more power.

[0057] Before the cycle begins, the maximum allowable power limit for each battery pack can also be obtained. and total system power In addition, the allocated power of each battery pack also needs to be checked. Power distribution status of each battery pack Overflow power Total overflow power Perform initialization. That is: ; ; ; .in, This indicates that the battery pack allocation is complete. The battery pack has reached [number]. ,but Otherwise, it is 0.

[0058] S54: Execute a cyclic process for each battery pack until a first preset condition is met. The cyclic process includes: executing a power allocation process for each battery pack until a second preset condition is met. The power allocation process includes: allocating power to each battery pack based on the state-of-charge difference, allocated power, and total system power, and updating the allocated power; judging the allocated power and the maximum allowable power limit; if the allocated power is less than the maximum allowable power limit, setting the power allocation status to incomplete; if the allocated power is not less than the maximum allowable power limit, using the maximum allowable power limit as the allocated power; calculating the overflow power of each battery pack and setting the power allocation status to completed; calculating the total overflow power of the energy storage battery pack based on the overflow power; when the total overflow power and the power allocation status of each battery pack do not meet the first preset condition, using the total overflow power as the total system power, and executing the power allocation process for each battery pack. The first preset condition is that the total overflow power is 0 or the power allocation status of all battery packs is completed; the second preset condition is that the current battery pack is the last battery pack in the energy storage battery pack.

[0059] Specifically, based on the state-of-charge difference, allocated power, and total system power, power is allocated to each battery pack, and the allocated power is updated. This includes: calculating the total state-of-charge difference of the energy storage battery pack based on the state-of-charge difference; calculating the power increment of each battery pack based on the state-of-charge difference, the total state-of-charge difference, and the total system power; and updating the allocated power based on the power increment and the allocated power.

[0060] Iterate through N battery packs until the second preset condition is met (the current battery pack is the last battery pack in the energy storage battery pack). Then according to their respective Percentage Perform power allocation to update The allocation calculation formula is as follows: ; in, This represents the total difference in the state of charge of the energy storage battery pack; the current power increment of the battery pack is... .

[0061] Secondly, determine the updated Does it exceed the capacity of the battery pack? If it does not exceed the battery pack's capacity. This indicates that the allocation is valid. The thermal state remains at 0, meaning the power distribution of this battery pack is incomplete. If the power distribution exceeds the capacity of this battery pack... Then Revised to Additionally, the excess portion is recorded as overflow power. And by summing them up, we can obtain the results. At the same time, the battery pack is marked as completed, i.e. .

[0062] Subsequently, an end condition judgment phase is performed, when the total overflow power and the power distribution state of each battery pack meet a first preset condition, the loop process is ended. The first preset condition is that the total overflow power is 0 or the power distribution state of all battery packs is 1. It can be understood that if the total overflow power is 0, it indicates that the total overflow power has been distributed, and the process is ended; if the power distribution state of all battery packs is 1, it indicates that all battery packs have reached the SOP limit value, and the process is ended even if there is still overflow power; if the above two conditions are not met, the next phase is entered.

[0063] When the total overflow power and the power distribution state of each battery pack do not meet the first preset condition, the total overflow power is distributed to the battery pack with the lowest state of charge, i.e. , and then the power distribution process is performed again for each battery pack, and the secondary distribution is continued for the battery pack that has not completed the distribution until the first preset condition is met.

[0064] Finally, the final distribution power of each battery pack is output, i.e. (i=1,…,N); if there is still total overflow power that cannot be distributed, i.e. , and the power distribution state of all battery packs is 1, the residual power is returned as the amount that cannot be distributed, and the host computer is suggested to take measures such as derating, current limiting, or alarm.

[0065] For example, assume that there are 3 battery packs (A, B, C) in the energy storage battery pack, the system total power that needs to be distributed by the current system is 90kW, , the state of charge value of each battery pack is A=80%, B=70%, and C=60%, respectively, and the SOP limit value of each battery pack is A=50kW, B=40kW, and C=30kW, respectively.

[0066] The state of charge difference value of each battery pack is calculated, i.e. , , The total state of charge difference value of the energy storage battery pack is 20+30+40=90.

[0067] The first power distribution is performed according to the state of charge difference value ratio, i.e. kW; is 30 kW; is 40 kW.

[0068] The distributed power is compared with the SOP limit value of itself, i.e.​​​​​​ This allocation is legal. (Not completed despite meeting the deadline); This allocation is legal. ; At this point, it has exceeded its own SOP limit, so take... kW, (The battery pack has been allocated); Overflow power =10kW, accumulated to The results of this round are as follows: kW, allocated power: A=20kW, B=30kW, C=30kW.

[0069] Entering the termination condition judgment phase. Because... The value is not 0, and neither battery pack A nor battery pack B has been fully allocated, so a secondary allocation is required.

[0070] Will kW, and reset to zero. It should be noted that at this point, only battery packs A and B, which have not yet been allocated, need to be allocated.

[0071] At this point, the total state of charge difference of the energy storage battery pack is 20 + 30 = 50. Performing a secondary distribution calculation, we obtain: kW; It is 36 kW. The allocated power is compared again with its own SOP limit: A: 24 < 50; B: 36 < 40. Neither exceeds the limit. Therefore... The current value is 0, which satisfies the first preset condition, thus ending the process.

[0072] The final allocation result is: kW kW kW; a total of 90kW, allocated and not exceeding its own SOP limit.

[0073] In this embodiment, power allocation is adaptively adjusted based on the difference between the current state of charge (SOC) value and the target SOC value of each battery pack. Under the premise of meeting the SOP limit of each battery pack, more power is allocated to battery packs with a larger SOC deviation from the target. The available power of the system is fully utilized through an iterative allocation mechanism to avoid resource waste. When the power cannot be fully allocated, the remaining power information can be output in a timely manner, which is convenient for the upper-level system to take power limiting or protection measures.

[0074] In some embodiments, the method further comprises: if the system total power does not satisfy the second power constraint condition; updating the maximum allowed power limit value of each battery pack in the energy storage battery pack through a maximum allowed power limit value amplification strategy; and selecting the equalized state of charge distribution strategy as the third power distribution strategy based on the maximum allowed power limit value.

[0075] The maximum allowed power limit value of each battery pack in the energy storage battery pack is updated through the maximum allowed power limit value amplification strategy, including: obtaining the maximum allowed power limit value of each battery pack in the energy storage battery pack; obtaining the overcurrent point power limit value of each battery pack; calculating the maximum allowed power total limit value of the energy storage battery pack according to the maximum allowed power limit value of each battery pack; calculating the target amplification power according to the system total power and the maximum allowed power total limit value; calculating the maximum allowed power difference value of each battery pack according to the overcurrent point power limit value and the maximum allowed power limit value; and updating the maximum allowed power limit value of each battery pack according to the maximum allowed power difference value, the target amplification power, and the maximum allowed power limit value.

[0076] When the system is in a charging state or a discharging state, if the first power constraint condition is satisfied but the second power constraint condition is not satisfied (i.e. ), the SOP total limit value can be amplified using the maximum allowed power limit value amplification strategy (SOP limit value amplification strategy) to meet the system total power requirement while ensuring that the overcurrent point total power limit value is not exceeded. The implementation process of the SOP limit value amplification strategy is as follows: The overcurrent point power limit value of each battery pack is obtained The maximum allowed power limit value of each battery pack is obtained , and the SOP total limit value is calculated according to the SOP limit value of each battery pack . The maximum allowed power difference value of each battery pack is calculated according to the overcurrent point power limit value and the maximum allowed power limit value , i.e. .

[0077] The target amplification power is calculated according to the system total power and the maximum allowed power total limit value , i.e. . .

[0078] The target amplification power is updated according to the maximum allowed power difference value ratio, i.e. ; ​It can be understood that when the total system power exceeds the original SOP total limit value but still does not reach the overcurrent point, the SOP limit value of each battery pack is amplified in proportion to the margin of each battery pack and the overcurrent point power limit value, so that the system can safely output / absorb greater power. On this basis, the above-mentioned balanced state of charge distribution strategy is used for power distribution.

[0079] For example, battery pack A and B, the original SOP limit value of A is 10 kW, the original SOP limit value of B is 15 kW, the overcurrent point power limit value of A is 20 kW, and the overcurrent point power limit value of B is 18 kW. The current state of charge value of A is 40%, and the current state of charge value of B is 60%.

[0080] First, SOP limit value amplification: the total system power = 30 kW > the original SOP total limit value = 25 kW; Calculate the maximum allowed power difference of battery pack A and battery pack B: A = 20-10 = 10 kW, B = 18-15 = 3 kW; Second, amplify in proportion to the maximum allowed power difference: the increment of battery A = (30-25) x (10 / (10+3)) ≈ 3.85 kW, that is, the updated SOP limit value of battery pack A is 13.85 kW; the increment of battery pack B = (30-25) x (3 / 13) ≈ 1.15 kW, that is, the updated SOP limit value of battery pack B is 16.15 kW.

[0081] Subsequently, the balanced state of charge distribution strategy is used: the current state of charge value of battery pack A is low, and more power should be allocated; the current state of charge value of battery pack B is high, and less power should be allocated, but the allocated power cannot exceed the updated SOP limit value of each battery pack. For details of the balanced state of charge distribution strategy, see the above-mentioned step S5.

[0082] In this embodiment, when the total system power exceeds the SOP total limit value but is still lower than the overcurrent point total power limit value, the SOP limit value of each battery pack can be moderately amplified to cover the current real-time power demand, and the power is distributed in proportion to the distance of each battery pack SOP limit value and the overcurrent point power limit value. On the one hand, the power potential of the battery pack can be fully released, and the problem that the total system power is limited due to the simple distribution according to the original SOP limit value proportion can be avoided, so as to improve the charging and discharging efficiency and the system load capacity; on the other hand, the safety distance of each battery pack and the overcurrent point power limit value is considered in the amplification process, so as to ensure that the power of each battery pack is still within the safety range, avoid the overcurrent protection from being triggered in advance, improve the service life of the battery and the safety of the system operation; in addition, the balanced state of charge distribution strategy can be combined to realize the balanced control of the battery pack SOC while amplifying the power, so as to further optimize the overall performance and stability of the system.

[0083] The embodiment of the present application provides a power distribution method, through dynamic monitoring and calculation of total system power, SOC and SOP limit value of each battery pack, when the total system power is less than the maximum allowed total power limit value of the energy storage battery group and the total system power is not greater than the total power limit value of the overcurrent point, power distribution is adjusted according to the SOC state of each battery pack, so that the SOC of each battery pack tends to be consistent, thereby improving the power balance between the battery packs, ensuring that the charging speed and the maximum load capacity in the whole use cycle are maximized, and the SOP limit value of each battery pack is considered, which does not exceed the safety power boundary, effectively prolongs the cycle life of the battery cell. When the total system power exceeds the total SOP limit value but does not reach the total power limit value of the overcurrent point, the SOP limit value of each battery pack is moderately amplified according to the safety distance proportion of the overcurrent power limit value, so as to meet the actual power demand, and at the same time, it is ensured that the amplified power is still in the safety range, the system power potential is fully released, and the charging and discharging efficiency is improved. In the working condition that the power further exceeds the total power limit value of the overcurrent point, an equal current distribution strategy is adopted, so that all the battery packs work at the same current at the same time, and the lower level overcurrent protection is triggered at the necessary moment, so as to avoid serious overcurrent of a single battery pack, and improve the overall stability and safety of the system. In addition, through the combination of SOC balancing and SOP limit value management, dynamic optimization control of the SOC and power of each battery pack under various working conditions is realized, the system power utilization rate, the battery life and the charging and discharging performance are considered, and the reliability, efficiency and safety of the whole energy storage system in practical application are significantly improved.

[0084] The embodiment of the present application also provides an energy management system 200, please refer to Figure 3 which shows a hardware structure schematic diagram of the energy management system 200 capable of executing the method of the above embodiment. The energy management system 200 comprises at least one processor 210 and a memory 220 connected with the at least one processor 210, Figure 3 The memory 220 stores instructions executable by the at least one processor 210, and the instructions are executed by the at least one processor 210 to enable the at least one processor 210 to execute the power distribution method of the above embodiment. The processor 210 and the memory 220 can be connected through a bus or other means, Figure 3 For example, the connection through the bus is taken as an example.

[0085] The memory 220 is a non-volatile computer readable storage medium, which can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules corresponding to the power distribution method in the embodiment of the present application. The processor 210 executes various function applications and data processing of the server by running the non-volatile software programs, instructions and modules stored in the memory 220, that is, the power distribution method of the above embodiment is realized.

[0086] The memory 220 can include a program storage area and a data storage area. The program storage area can store an operating system, application programs required by at least one function, and the like. The data storage area can store data created according to usage of the computing device, and the like. In addition, the memory 220 can include a high-speed random access memory, and can also include a nonvolatile memory such as at least one disk memory device, a flash memory device, or other nonvolatile solid-state memory device. In some embodiments, the memory 220 can optionally include a memory disposed remotely with respect to the processor 210, which can be connected to the computing device through a network. Examples of the network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0087] One or more modules are stored in the memory 220, and when executed by the one or more processors 210, perform the power distribution method of the above-described embodiments.

[0088] The above-described product can perform the method provided by the embodiments of the present application, and has the corresponding function modules and beneficial effects of performing the method. Technical details not described in detail in the embodiments can be referred to the power distribution method of the embodiments of the present application.

[0089] The embodiments of the present application provide a non-volatile computer readable storage medium, which stores computer executable instructions. The computer executable instructions are executed by one or more processors to enable at least one processor to perform the power distribution method of the above-described embodiments. For example, the non-volatile computer readable storage medium can be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CDROM), a magnetic tape, a floppy disk, and an optical data storage device, etc.

[0090] From the above description of the embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment method can be realized by means of software plus a general hardware platform required, of course, it can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which is stored in a storage medium (such as a ROM / RAM, a magnetic disk, or an optical disc) and includes a number of instructions to make a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) execute the methods described in the various embodiments of the present application.

[0091] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and are not limited; under the idea of the present application, the technical features in the above examples or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in detail for simplicity; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power allocation method applied to an energy storage system, characterized in that, The method comprises: acquiring system total power of the energy storage system; obtaining a system state of the energy storage system according to the system total power; when the system state is an idle state, selecting a first power distribution strategy; when the system state is a charging state or a discharging state and the system total power does not satisfy a first power constraint condition, selecting a second power distribution strategy; when the system state is the charging state or the discharging state and the system total power satisfies the first power constraint condition, if the system total power satisfies a second power constraint condition, selecting a third power distribution strategy.

2. The power distribution method of claim 1, wherein, The step of selecting the first power distribution strategy when the system state is the idle state comprises: when the system state is the idle state, selecting a maximum allowable power proportion distribution strategy as the first power distribution strategy.

3. The power distribution method of claim 2, wherein, The step of selecting the second power distribution strategy when the system state is the charging state or the discharging state and the system total power does not satisfy the first power constraint condition comprises: when the system state is the charging state or the discharging state, judging whether the system total power satisfies the first power constraint condition; if the system total power does not satisfy the first power constraint condition, selecting an equal current distribution strategy as the second power distribution strategy; wherein the first power constraint condition is that the system total power is not greater than an overcurrent point total power limit value.

4. The power distribution method of claim 3, wherein, The step of selecting the third power distribution strategy when the system state is the charging state or the discharging state and the system total power satisfies the first power constraint condition, if the system total power satisfies the second power constraint condition, comprises: when the system state is the charging state or the discharging state, if the system total power satisfies the first power constraint condition; judging whether the system total power satisfies the second power constraint condition; if the system total power satisfies the second power constraint condition, selecting a balanced state of charge distribution strategy as the third power distribution strategy; wherein the second power constraint condition is that the system total power is not greater than a maximum allowable power total limit value of the energy storage battery pack.

5. The power distribution method of claim 4, wherein, The method further comprises: if the system total power does not satisfy the second power constraint condition; updating maximum allowable power limit values of each battery pack in the energy storage battery pack through a maximum allowable power limit value amplification strategy; based on the maximum allowable power limit values, selecting the balanced state of charge distribution strategy as the third power distribution strategy.

6. The power distribution method of claim 5, wherein, The step of selecting the balanced state of charge distribution strategy as the third power distribution strategy comprises: setting a target state of charge value of the energy storage battery pack; calculating state of charge difference values of each battery pack in the energy storage battery pack according to the target state of charge value; initializing allocated powers of the each battery pack and power distribution states of the each battery pack; performing a loop process on the each battery pack until a first preset condition is satisfied, the loop process comprising: The power distribution process is performed on each battery pack until a second preset condition is met, the power distribution process including: distributing power to each battery pack based on the state of charge difference, the allocated power, and the system total power, updating the allocated power; judging the allocated power and the maximum allowable power limit; if the allocated power is less than the maximum allowable power limit, setting the power distribution state to an incomplete state; if the allocated power is not less than the maximum allowable power limit, taking the maximum allowable power limit as the allocated power; calculating the overflow power of each battery pack, and setting the power distribution state to a completed state; calculating the total overflow power of the energy storage battery pack according to the overflow power; When the total overflow power and the power distribution state of each battery pack do not meet the first preset condition, the total overflow power is taken as the system total power, and the power distribution process is performed on each battery pack.

7. The power distribution method of claim 6, wherein, The power distribution process based on the state of charge difference, the allocated power, and the system total power includes: calculating a total state of charge difference of the energy storage battery pack according to the state of charge difference; calculating a power increment of each battery pack according to the state of charge difference, the total state of charge difference, and the system total power; updating the allocated power according to the power increment and the allocated power.

8. The power distribution method of claim 5, wherein, The maximum allowable power limit of each battery pack in the energy storage battery pack is updated through a maximum allowable power limit amplification strategy, including: obtaining the maximum allowable power limit of each battery pack in the energy storage battery pack; obtaining an overcurrent point power limit of each battery pack; calculating a total maximum allowable power limit of the energy storage battery pack according to the maximum allowable power limit of each battery pack; calculating a target amplification power according to the system total power and the total maximum allowable power limit; calculating a maximum allowable power difference of each battery pack according to the overcurrent point power limit and the maximum allowable power limit; updating the maximum allowable power limit of each battery pack according to the maximum allowable power difference, the target amplification power, and the maximum allowable power limit.

9. An energy management system, characterized by including: at least one processor; and a memory connected to the at least one processor in communication; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-8.

10. A non-transitory computer readable storage medium, comprising: The non-volatile computer readable storage medium stores computer executable instructions, when the computer executable instructions are executed by the energy management system, the energy management system executes the method of any one of claims 1-8.

Images