Energy storage system and equalization control method, device and storage medium thereof

Abstract

The application discloses an energy storage system and a balancing control method and device thereof and a storage medium, and relates to the technical field of energy storage. The method comprises the following steps: determining a to-be-balanced battery cluster according to state information of each battery cluster; distributing target scheduling power to each energy storage unit, and the scheduling power distributed to the energy storage unit where the to-be-balanced battery cluster is located is not more than the maximum bearing power of the to-be-balanced battery cluster; and controlling a plurality of energy storage converters to respectively schedule the to-be-balanced battery cluster and the battery cluster in a non-balanced energy storage unit according to the scheduling power distributed to the corresponding energy storage unit, wherein the non-balanced energy storage unit refers to an energy storage unit that does not contain the to-be-balanced battery cluster. The method can achieve the balancing control of a single battery cluster while meeting the scheduling demand of the scheduling work of the energy storage converter, thereby prolonging the service life of the energy storage unit.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and more specifically, to an energy storage system and its equalization control method, device and storage medium. Background Technology

[0002] A power conversion system (PCS) can control the charging and discharging of multiple battery clusters in an energy storage unit and perform power scheduling on the multiple battery clusters in the energy storage unit.

[0003] In related technologies, multiple battery clusters in an energy storage unit are directly connected in parallel, and the energy storage converter needs to simultaneously manage these multiple battery clusters. If a battery cluster malfunctions, such as having a significantly lower charge level than other battery clusters in the same energy storage unit, it will cause the energy storage converter to malfunction in managing the energy storage unit and will also affect the lifespan of the energy storage unit. Summary of the Invention

[0004] This application provides an energy storage system and its equalization control method, device and storage medium.

[0005] In a first aspect, embodiments of this application provide a method for balancing control of an energy storage system. The energy storage system includes multiple energy storage units and multiple energy storage converters that correspond one-to-one. The AC sides of the multiple energy storage converters are connected to each other, and the DC sides of the energy storage converters are respectively connected to multiple battery clusters in the corresponding energy storage units. The method includes: determining the battery cluster to be balanced based on the state information of each battery cluster; allocating the target scheduling power to each of the energy storage units, wherein the scheduling power allocated to the energy storage unit containing the battery cluster to be balanced does not exceed the maximum power that the battery cluster to be balanced can withstand; controlling the multiple energy storage converters to schedule the battery cluster to be balanced and the battery clusters in the unbalanced energy storage units according to the scheduling power allocated to the corresponding energy storage units, wherein the unbalanced energy storage unit refers to an energy storage unit that does not contain the battery cluster to be balanced.

[0006] In some embodiments, the state information of the battery cluster includes the power information of the battery cluster; determining the battery cluster to be balanced based on the state information of each battery cluster includes: for each energy storage unit, if the power difference between battery clusters in the energy storage unit is greater than the balancing threshold, then in the charging case, the battery cluster with the smallest power in the energy storage unit is taken as the battery cluster to be balanced, and / or, in the discharging case, the battery cluster with the largest power in the energy storage unit is taken as the battery cluster to be balanced.

[0007] In some embodiments, before controlling the plurality of energy storage converters to schedule the battery clusters in the unbalanced energy storage unit according to the scheduling power allocated to the corresponding energy storage unit, the method further includes: controlling the switches corresponding to the battery clusters in the unbalanced energy storage unit to close, and controlling the switches corresponding to the battery clusters in the energy storage unit where the balanced battery cluster is located to open; wherein, the energy storage unit further includes a plurality of switches corresponding one-to-one with the plurality of battery clusters, and the battery clusters are connected to the DC side of the corresponding energy storage converter through the corresponding switches.

[0008] In some embodiments, the method further includes: when the charge of the battery cluster to be balanced reaches the average charge of the energy storage unit where the battery cluster to be balanced is located, controlling the switches corresponding to the battery clusters other than the battery cluster to be balanced in the energy storage unit where the battery cluster to be balanced is located to close, and returning to the step of determining the battery cluster to be balanced based on the state information of each battery cluster.

[0009] In some embodiments, the state information of the battery clusters further includes normal state and abnormal state; before determining the battery clusters to be balanced based on the state information of each battery cluster, the method further includes: controlling the switch corresponding to the battery cluster in the normal state to close.

[0010] In some embodiments, before determining the battery clusters to be balanced based on the state information of each battery cluster, the method further includes: when it is determined based on the state information of each battery cluster that there are battery clusters that need to be recharged, initiating a battery recharge request.

[0011] In some implementations, determining the presence of a battery cluster requiring recharging based on the state information of each battery cluster includes: for each energy storage unit, if the power difference between battery clusters in the energy storage unit is greater than the recharging threshold, or if there is a battery cluster in the energy storage unit with a power level lower than the recharging start value, then it is determined that there is a battery cluster requiring recharging.

[0012] In some implementations, the power allocated to the unbalanced energy storage unit does not exceed the maximum power that a single energy storage unit can handle.

[0013] Secondly, embodiments of this application provide an equalization control device for an energy storage system. The energy storage system includes multiple energy storage units and multiple energy storage converters that correspond one-to-one. The AC sides of the multiple energy storage converters are connected to each other, and the DC sides of the energy storage converters are respectively connected to multiple battery clusters in the corresponding energy storage units. The device includes: a determining unit, used to determine the battery cluster to be equalized based on the state information of each battery cluster; an allocation unit, used to allocate a target scheduling power to each of the energy storage units, wherein the scheduling power allocated to the energy storage unit containing the battery cluster to be equalized does not exceed the maximum power that the battery cluster to be equalized can withstand; and a control module, used to control the multiple energy storage converters to schedule the battery cluster to be equalized and the battery clusters in the unbalanced energy storage units according to the scheduling power allocated to the corresponding energy storage units, wherein the unbalanced energy storage unit refers to an energy storage unit that does not contain the battery cluster to be equalized.

[0014] Thirdly, embodiments of this application provide an energy storage system, comprising: a plurality of energy storage units and a plurality of energy storage converters corresponding to each other, wherein the AC sides of the plurality of energy storage converters are connected to each other, and the DC side of the energy storage converters is respectively connected to a plurality of battery clusters in the corresponding energy storage units; and the device described in the second aspect above.

[0015] In some embodiments, the energy storage unit further includes a plurality of switches corresponding one-to-one with the plurality of battery clusters, the battery clusters being connected to the DC side of the corresponding energy storage converter through the corresponding switches.

[0016] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method described in the first aspect above.

[0017] The energy storage system, its equalization control method, apparatus, and storage medium provided in this application allow for independent scheduling of each battery cluster within an energy storage unit. The process includes: determining the battery cluster to be equalized based on the state information of each battery cluster, and allocating a target scheduling power to each energy storage unit, wherein the scheduling power allocated to the energy storage unit containing the battery cluster to be equalized does not exceed the maximum power that the battery cluster to be equalized can withstand; controlling multiple energy storage converters to schedule the battery cluster to be equalized and the battery clusters in unbalanced energy storage units according to the scheduling power allocated to their respective energy storage units, wherein unbalanced energy storage units refer to energy storage units that do not contain the battery cluster to be equalized. Therefore, while the energy storage converters perform scheduling operations to meet scheduling requirements, individual equalization control of the battery clusters can be achieved, thereby improving the lifespan of the energy storage unit. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein:

[0019] Figure 1 This is a schematic diagram of the structure of an energy storage system according to an embodiment of this application;

[0020] Figure 2 This is a flowchart of an energy storage system equalization control method according to an embodiment of this application;

[0021] Figure 3 This is a schematic diagram of switch control in an energy storage system according to one embodiment of this application;

[0022] Figure 4 This is a flowchart of an energy storage system equalization control method according to a specific embodiment of this application;

[0023] Figure 5 This is a structural block diagram of the equalization control device of the energy storage system according to an embodiment of this application;

[0024] Figure 6 This is a structural block diagram of an energy storage system according to an embodiment of this application.

[0025] Reference numerals: energy storage system 1000, energy storage unit 100, energy storage converter 200, energy storage system equalization control device 500, determination module 10, distribution module 20 and control module 30. Detailed Implementation

[0026] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are optional and are only used to explain the embodiments of this application, and should not be construed as limiting the embodiments of this application.

[0027] Due to differences in the production consistency of each battery cluster in the energy storage unit, uneven operating temperature, and the cumulative effect of long-term charge-discharge cycles, the state (such as charge level) between battery clusters will gradually deviate. If, as indicated in the background art, multiple battery clusters in the energy storage unit are directly connected in parallel, once the state between the battery clusters deviates, it will lead to abnormal scheduling of the energy storage unit by the energy storage converter and affect the lifespan of the energy storage unit.

[0028] To address the aforementioned technical problems, this application provides an energy storage system and its equalization control method.

[0029] In the embodiments of this application, such as Figure 1As shown, the energy storage system 1000 includes multiple energy storage units 100 and multiple energy storage converters 200 that correspond one-to-one. The AC sides of the multiple energy storage converters 200 are connected to each other and are suitable for direct or indirect (e.g., through a transformer) connection to the AC power grid. The DC side of the energy storage converter 200 is connected to the corresponding energy storage unit. The energy storage unit includes multiple battery clusters, each of which can be charged and discharged.

[0030] Specifically, refer to Figure 1 The number of energy storage units 100 and energy storage converters 200 is N, where N is an integer greater than 1. The N energy storage units 100 are denoted as Unit(1) to Unit(N), and the N energy storage converters 200 are denoted as PCS(1) to PCS(N). The DC sides of Unit(n) and PCS(n) are connected, and the AC sides of PCS(1) to PCS(N) are connected. Here, n takes any integer from 1 to N. For example, if n is 1, Unit(1) is connected to the DC side of PCS(1); if n is N, Unit(N) is connected to the DC side of PCS(N).

[0031] To enable independent scheduling of each battery cluster in the energy storage unit 100, a switching circuit can be set for each battery cluster. This switching circuit is used to establish or disconnect the electrical connection between the battery cluster and the corresponding energy storage converter 200.

[0032] In one embodiment, the switching circuit includes at least one switch, as referenced. Figure 1 Unit(n) can include An battery clusters and An switches. In Unit(n), the An battery clusters can be denoted as Rack(1) to Rack(An), and the An switches can be denoted as S(1) to S(An). Rack(an) can be connected to the DC side of PCS(n) through S(an), where an takes any integer from 1 to An. Optionally, the switches can be connected in series between any two series-connected cells in the battery cluster.

[0033] Understandably, the independent design of multiple battery clusters within the energy storage system 1000 can be achieved through the configuration of the switching circuits. When the energy storage system 1000 needs to be scheduled, if one of its battery clusters malfunctions, the switching circuit corresponding to that malfunctioning battery cluster is disconnected, while the switching circuits corresponding to the other battery clusters are turned on, thus enabling scheduling. In this case, the malfunctioning battery cluster will not affect the scheduling of other battery clusters by the energy storage converter 200.

[0034] Figure 2This is a flowchart of an energy storage system balancing control method according to an embodiment of this application. The balancing control method is implemented based on the aforementioned energy storage system and can be executed by a Smart Control Unit (SCU). The SCU can be configured to control multiple energy storage converters; each energy storage unit can be equipped with a Battery Management System (BMS) to monitor the status information of the battery clusters in the corresponding energy storage unit and control the controllable devices in the corresponding energy storage unit. The SCU can communicate with each BMS.

[0035] like Figure 2 As shown, the equalization control method for energy storage systems includes:

[0036] S21, determine the battery clusters to be balanced based on the status information of each battery cluster.

[0037] In some embodiments of this application, before step S21 is executed, a target scheduling power is determined in response to a scheduling instruction.

[0038] The AC side of the energy storage converter can be directly or indirectly (e.g., through a transformer) connected to the power grid. Dispatch commands can be charging or discharging commands sent by the energy management system (EMS) of the energy storage system based on real-time power demand and grid operating conditions. This EMS can communicate with the smart unit board. Upon receiving the dispatch command, the smart unit board can determine the target dispatch power, including the target charging power and the target discharging power.

[0039] In one embodiment, the state information of the battery cluster includes the power information of the battery cluster; determining the battery cluster to be balanced based on the state information of each battery cluster includes: for each energy storage unit, if the power difference between battery clusters in the energy storage unit is greater than the balancing threshold, then when the scheduling instruction is a charging instruction, the battery cluster with the smallest power in the energy storage unit is taken as the battery cluster to be balanced, and / or, when the scheduling instruction is a discharging instruction, the battery cluster with the largest power in the energy storage unit is taken as the battery cluster to be balanced.

[0040] For example, in the initial state, the smart unit board can acquire the status information of each energy storage converter and the status information (including power information) of each battery cluster in real time. The status information of the battery clusters can be provided to the smart unit board by the corresponding battery management system; the power information can be characterized by the State of Charge (SOC). When the smart unit board receives a scheduling command, it can also determine whether there is a battery cluster to be balanced in each energy storage unit. Specifically, it can calculate the difference between the maximum and minimum SOC values ​​(i.e., the power difference). If this difference is greater than the balancing threshold (which can be within the range of 0% to 100%, e.g., 0%), then when the scheduling command is a charging command, the battery cluster with the smallest SOC value in the energy storage unit is selected as the battery cluster to be balanced, so that it can be charged during subsequent scheduling, thereby achieving balancing; and when the scheduling command is a discharging command, the battery cluster with the largest SOC value in the energy storage unit is selected as the battery cluster to be balanced, so that it can be discharged during subsequent scheduling, thereby achieving balancing.

[0041] In one implementation, the balancing function of the energy storage system can be manually triggered or automatically triggered based on the battery cluster's charge information (e.g., the charge difference between battery clusters in at least one energy storage unit is greater than the aforementioned balancing threshold). When performing balancing control on the energy storage system, upon receiving a scheduling command, it can also determine whether the balancing function is enabled. If enabled, subsequent balancing control is executed; if not enabled, it returns to the aforementioned initial state, or performs routine scheduling operations. For example, routine scheduling operations may refer to directly allocating the target scheduling power equally to each energy storage unit without determining the battery clusters to be balanced, and directly using the battery clusters of each energy storage unit as the target battery clusters for scheduling.

[0042] S22, the target scheduling power is allocated to each energy storage unit, wherein the scheduling power allocated to the energy storage unit where the battery cluster to be balanced is located does not exceed the maximum power that the battery cluster to be balanced can withstand.

[0043] It should be noted that the power allocated to the unbalanced energy storage unit must not exceed the maximum power that a single energy storage unit can withstand, so that the dispatched power does not exceed the capacity of each energy storage unit and avoids damage to the battery clusters in the energy storage unit.

[0044] In one embodiment, assuming that each energy storage unit comprises the same number of battery clusters and that each battery cluster is in a normal state, the target scheduling power is divided into two parts. One part is allocated to the energy storage unit containing the battery cluster to be balanced, and the other part is evenly allocated to the unbalanced energy storage units. The scheduling power allocated to the energy storage unit containing the battery cluster to be balanced is 1 / M of the scheduling power allocated to each unbalanced energy storage unit, where M is the number of battery clusters in the energy storage unit.

[0045] In another implementation, the target scheduling power is directly and evenly distributed to the target battery clusters at various locations, wherein the target battery clusters include balanced battery clusters and battery clusters in unbalanced energy storage units, and the target battery clusters are battery clusters in a normal state.

[0046] When there are multiple battery clusters to be balanced, the two implementation methods described above can be used to balance multiple battery clusters simultaneously, resulting in better timeliness. If the scheduling power allocated using the two implementation methods exceeds the limit, the battery clusters to be balanced can be balanced in batches. For example, the first batch of battery clusters to be balanced can be determined from multiple battery clusters. The target scheduling power can be allocated to the energy storage unit where the first batch of balanced battery clusters is located and other energy storage units (including energy storage units where battery clusters to be balanced are located, excluding those in the first batch) using the two implementation methods described above. Subsequently, the first batch of battery clusters to be balanced is balanced first, and the other battery clusters to be balanced are scheduled as ordinary battery clusters. After the first batch of battery clusters to be balanced is balanced, the process returns to step S21 to determine the next batch of battery clusters to be balanced, and so on, until all battery clusters to be balanced are balanced, or the scheduling task ends. The first batch of battery clusters to be balanced can be one or more battery clusters with large power differences, and the allocated scheduling power does not exceed the limit.

[0047] In the above implementation, for the energy storage unit containing the battery cluster to be balanced, only the battery cluster to be balanced is scheduled to achieve balancing. Therefore, the allocated scheduling power is less than the scheduling power allocated to other energy storage units. It can also be considered that the energy storage unit containing the battery cluster to be balanced has a power limit, and the limited power is distributed to other energy storage units, while the overall scheduling power remains unchanged. In other words, the sum of the scheduling power allocated to multiple energy storage units is still the target scheduling power. That is, during the scheduling process, the overall scheduling power of the energy storage system remains unchanged, thereby ensuring the stability of the power grid.

[0048] In some embodiments of this application, if, regardless of the allocation method, there are energy storage units whose allocated scheduling power is greater than the corresponding maximum allowable scheduling power, for example, if the scheduling power allocated to the energy storage unit where the battery cluster to be balanced is located is greater than the maximum allowable scheduling power of the battery cluster to be balanced, it indicates that the current scheduling exceeds the battery cluster's capacity (over-limit). Forced scheduling may damage the battery cluster. In this case, the scheduling process can be terminated and the process can be returned to the initial state described above.

[0049] S23, control multiple energy storage converters to schedule the battery clusters in the unbalanced energy storage unit and the battery clusters in the unbalanced energy storage unit according to the scheduling power allocated to the corresponding energy storage unit. The unbalanced energy storage unit refers to the energy storage unit that does not contain the battery cluster to be balanced.

[0050] The energy storage system balancing control method of this application embodiment is based on the design of independently schedulable battery clusters. It allocates different scheduling power to the energy storage unit where the battery cluster to be balanced is located and other energy storage units, and performs individual scheduling on the battery cluster to be balanced. While meeting the scheduling requirements, it can achieve the power balance of the battery cluster in the energy storage unit where the battery cluster to be balanced is located, thereby improving the life of the energy storage unit.

[0051] In some embodiments of this application, before controlling multiple energy storage converters to schedule the battery clusters in the unbalanced energy storage unit according to the scheduling power allocated to the corresponding energy storage unit, the method further includes: controlling the switches corresponding to the battery clusters to be balanced and the battery clusters in the unbalanced energy storage unit to close, and controlling the switches corresponding to the battery clusters in the energy storage unit where the balanced battery cluster is located to open, except for the battery cluster to be balanced; wherein, the energy storage unit also includes multiple switches corresponding one-to-one with multiple battery clusters, and the battery clusters are connected to the DC side of the corresponding energy storage converter through the corresponding switches.

[0052] For example, when it is determined that the balancing function of the energy storage system is activated, and there is a difference in charge between battery clusters of energy storage units that is greater than the balancing threshold, the battery clusters that need to be balanced are identified, and the first energy storage unit (containing the battery clusters to be balanced) and the second energy storage unit (excluding the battery clusters to be balanced) that do not need to be balanced are identified from Unit(1) to Unit(N). For example, the battery cluster to be balanced is Rack(2) in Unit(2), the first energy storage unit is Unit(2), and the second energy storage unit is the energy storage unit other than Unit(2) in Unit(1) to Unit(N), such as Figure 3 As shown, before the energy storage converter is controlled to schedule the target battery cluster, the switches in the second energy storage unit are closed, the switch S(2) corresponding to Rack(2) in Unit(2) is closed, and the switches in Unit(2) except S(2) are opened so that the target battery clusters can be scheduled in the future.

[0053] In some embodiments of this application, the state information of the battery clusters also includes normal state and abnormal state; before determining the battery clusters to be balanced based on the state information of each battery cluster, the method further includes: controlling the closing of the switch corresponding to the battery cluster in the normal state.

[0054] For example, in the initial state, the status information of each battery cluster acquired by the intelligent unit board includes normal and abnormal states, and the status information of each energy storage converter also includes normal and abnormal states. Subsequently, the intelligent unit board can notify each battery management system via command instructions. Upon receiving the command instructions, the battery management system controls the closing of the switches corresponding to the normal battery clusters connected to the normal energy storage converters to prepare for subsequent scheduling. In other words, before scheduling, the switches corresponding to the normal battery clusters can be closed first, so that scheduling can be performed directly during scheduling. Correspondingly, when there are battery clusters to be balanced, only the switches corresponding to the battery clusters other than the one to be balanced in the energy storage unit containing the battery cluster to be balanced need to be opened, reducing control complexity.

[0055] In some embodiments of this application, when the charge of the battery cluster to be balanced reaches the average charge of the energy storage unit where the battery cluster to be balanced is located, the switches corresponding to the battery clusters other than the battery cluster to be balanced in the energy storage unit where the battery cluster to be balanced is located are closed, and the process returns to determining the battery cluster to be balanced based on the state information of each battery cluster.

[0056] In one implementation, after executing step S23, the intelligent unit board can detect the power information of the battery cluster to be balanced in real time and determine whether the power information reaches the average power value of the energy storage unit where the battery cluster to be balanced is located. The average power value can be the average power value of all battery clusters in the energy storage unit where the battery cluster to be balanced is located, or it can be the average power value of the battery clusters excluding the battery cluster to be balanced. The difference is that the former changes with the power of the battery cluster to be balanced, while the latter does not change with the power of the battery cluster to be balanced, resulting in lower processing complexity. If the power information of the battery cluster to be balanced reaches the average power value, it indicates that the battery cluster to be balanced has been balanced. At this point, the balancing control of the battery cluster to be balanced can be terminated, and the switches corresponding to the battery clusters excluding the battery cluster to be balanced in the energy storage unit can be closed. Then, the process returns to determining the battery cluster to be balanced based on the status information of each battery cluster for the next round of balancing, until there are no more battery clusters to be balanced in the energy storage system or the scheduling task ends. It should be understood that when there are no battery clusters to be balanced in the energy storage system or when the scheduling task ends, the system can return to the initial state described above; when there are no battery clusters to be balanced in the energy storage system, the energy storage system can also be subjected to regular scheduling work.

[0057] In some embodiments of this application, before determining the battery clusters to be balanced based on the state information of each battery cluster, the method further includes: when it is determined based on the state information of each battery cluster that there are battery clusters that need to be recharged, initiating a battery recharge request.

[0058] In this embodiment, the battery replenishment request can be used to generate scheduling instructions or to trigger replenishment control between energy storage units in the energy storage system. Determining the existence of battery clusters that need replenishment based on the status information of each battery cluster can include: for each energy storage unit, if the power difference between battery clusters in the energy storage unit is greater than the replenishment threshold, or if there is a battery cluster in the energy storage unit with a power level lower than the replenishment start value, then it is determined that there is a battery cluster that needs replenishment.

[0059] The charging threshold value can be determined based on the actual battery cluster characteristics and scheduling conditions, and its range can be 20% to 100%, for example, 30%. In one embodiment, the charging threshold is greater than the aforementioned equalization threshold. The charging start value can be determined based on the scheduling conditions, and its range can be 0% to 20%, for example, 10%. If there is a discharge situation in the scheduling, the charging start value can be set to 0.

[0060] For example, after controlling the closing of the switch corresponding to the normal battery cluster based on the status information of the energy storage converter and the battery cluster, the smart unit board can determine whether a battery cluster needs to be recharged based on the power information of each battery cluster. For each energy storage unit, if the power difference between battery clusters in the energy storage unit is greater than the recharge threshold, or if there is a battery cluster in the energy storage unit with a power lower than the recharge start value, then it is determined that there is a battery cluster that needs to be recharged. At this time, the smart unit board can, on the one hand, initiate a battery recharge request to the energy management system so that the energy management system can issue scheduling instructions to realize the scheduling between the energy storage system and the external power grid; on the other hand, it can control the energy storage converter to perform scheduling between energy storage units within the energy storage system.

[0061] In one implementation, when it is determined that there are battery clusters that need to be recharged based on the status information of each battery cluster, the smart unit board can also report battery cluster alarm information to the energy management system.

[0062] The following is combined with Figure 4 This application describes a method for equalization control of an energy storage system according to a specific embodiment.

[0063] like Figure 4 As shown, the energy storage system's equalization control method includes the following process:

[0064] S41, Begin;

[0065] S42, real-time acquisition of status information of each battery cluster;

[0066] S43 controls the closing of the switch corresponding to the battery cluster in normal operation;

[0067] S44, determine if there is a scheduling instruction. If yes, proceed to step S47; otherwise, execute step S45.

[0068] S45, determine whether there is a charging unit or a battery cluster with a charge level lower than the charging start value. If so, proceed to step S46; otherwise, return to step S42.

[0069] Among them, the replenishment unit is an energy storage unit where the difference in charge between battery clusters is greater than the replenishment threshold.

[0070] S46, initiates a battery charging request;

[0071] S47, determine whether there is a scheduling balance unit. If yes, proceed to step S48; otherwise, return to step S42.

[0072] Among them, the scheduling and balancing unit is an energy storage unit where the difference in power between battery clusters is greater than the balancing threshold.

[0073] S48, determine whether charging is currently in progress. If yes, proceed to step S49; otherwise, proceed to step S55.

[0074] The scheduling instructions determine whether the battery is currently charging or discharging. For charging, the battery cluster to be balanced is the one with the lowest capacity in the scheduling balancing unit; for discharging, the battery cluster to be balanced is the one with the highest capacity in the scheduling balancing unit.

[0075] S49 limits the charging power of the scheduling and balancing unit and shares the limited charging power with other energy storage units;

[0076] Among them, the scheduling and balancing unit is the energy storage unit where the battery cluster to be balanced is located.

[0077] S50, determine whether the charging power allocated to other energy storage units sharing the charging power exceeds their maximum capacity. If it does, cancel step S49 and return to step S42; otherwise, execute step S51.

[0078] S51, keep the switch corresponding to the battery cluster with the smallest power in the scheduling and balancing unit closed, and keep the switches corresponding to other battery clusters in the scheduling and balancing unit open;

[0079] S52, charging the corresponding battery clusters based on the allocated charging power;

[0080] S53, determine whether the battery clusters in the scheduling and balancing unit have reached the average battery level of the unit. If so, proceed to step S54; otherwise, return to step S53.

[0081] S54, close the switches corresponding to all normal battery clusters in the scheduling and balancing unit where the battery cluster whose charge has reached the average charge of the unit is located, and return to step S47.

[0082] S55 limits the discharge power of the dispatch equalization unit and distributes the limited discharge power to other energy storage units.

[0083] S56, determine whether the discharge power allocated to other energy storage units sharing the discharge power exceeds their maximum withstand power. If it does, cancel step S55 and return to step S42; otherwise, execute step S57.

[0084] S57, keep the switch corresponding to the battery cluster with the largest capacity in the scheduling and balancing unit closed, and keep the switches corresponding to other battery clusters in the scheduling and balancing unit open;

[0085] S58 controls the corresponding battery clusters to discharge based on the allocated discharge power;

[0086] S59, determine whether the battery clusters in the scheduling and balancing unit have reached the unit power average. If so, proceed to step S60; otherwise, return to step S58.

[0087] S60, close the switches corresponding to all normal battery clusters in the scheduling and balancing unit where the battery cluster whose charge has reached the average charge of the unit is located, and return to step S47.

[0088] Corresponding to the energy storage system equalization control method in the above embodiments, this application proposes an energy storage system equalization control device.

[0089] Figure 5 This is a structural block diagram of the equalization control device of the energy storage system according to an embodiment of this application. The equalization control device 500 is implemented based on the energy storage system 1000 of the above embodiment and can be the aforementioned intelligent unit board.

[0090] like Figure 5 As shown, the equalization control device 500 includes: a determination module 10, an allocation module 20, and a control module 30.

[0091] The determination module 10 is used to determine the battery clusters to be balanced based on the status information of each battery cluster. The allocation module 20 is used to allocate the target scheduling power to each energy storage unit, wherein the scheduling power allocated to the energy storage unit containing the battery cluster to be balanced does not exceed the maximum power that the battery cluster to be balanced can withstand. The control module 30 is used to control multiple energy storage converters to schedule the battery clusters to be balanced and the battery clusters in the unbalanced energy storage units according to the scheduling power allocated to the corresponding energy storage units, wherein the unbalanced energy storage unit refers to an energy storage unit that does not contain the battery cluster to be balanced.

[0092] For example, the power allocated to an unbalanced energy storage unit does not exceed the maximum power that a single energy storage unit can handle.

[0093] In some embodiments of this application, the state information of the battery cluster includes the power information of the battery cluster; determining the battery cluster to be balanced based on the state information of each battery cluster includes: for each energy storage unit, if the power difference between battery clusters in the energy storage unit is greater than the balancing threshold, then in the charging case, the battery cluster with the smallest power in the energy storage unit is taken as the battery cluster to be balanced, and / or, in the discharging case, the battery cluster with the largest power in the energy storage unit is taken as the battery cluster to be balanced.

[0094] In some embodiments of this application, the energy storage unit further includes multiple switches corresponding to multiple battery clusters one-to-one. The battery clusters are connected to the DC side of the corresponding energy storage converter through the corresponding switches. Before the control module 30 controls the multiple energy storage converters to schedule the battery clusters to be balanced and the battery clusters in the unbalanced energy storage unit according to the scheduling power allocated to the corresponding energy storage unit, it also controls the switches corresponding to the battery clusters to be balanced and the battery clusters in the unbalanced energy storage unit to be closed, and controls the switches corresponding to the battery clusters in the energy storage unit where the balanced battery cluster is located to be opened, except for the battery cluster to be balanced.

[0095] In some embodiments of this application, when the power of the battery cluster to be balanced reaches the average power of the energy storage unit where the battery cluster to be balanced is located, the control module 30 is further configured to control the switches corresponding to the battery clusters other than the battery cluster to be balanced in the energy storage unit where the battery cluster to be balanced is located to close, and notify the determination module 10 to continue to determine the battery cluster to be balanced based on the status information of each battery cluster.

[0096] In some embodiments of this application, the state information of the battery clusters also includes normal state and abnormal state; before determining the battery clusters to be balanced based on the state information of each battery cluster, the control module 30 is also used to control the closing of the switch corresponding to the battery cluster in the normal state.

[0097] In some embodiments of this application, before determining the battery clusters to be balanced based on the state information of each battery cluster, the determining module 10 is further configured to: initiate a battery charging request when it is determined based on the state information of each battery cluster that there are battery clusters that need to be charged.

[0098] In some embodiments of this application, determining the presence of battery clusters that need to be recharged based on the status information of each battery cluster includes: for each energy storage unit, if the difference in charge between battery clusters in the energy storage unit is greater than the recharge threshold, or if there is a battery cluster in the energy storage unit with a charge lower than the recharge start value, then it is determined that there is a battery cluster that needs to be recharged.

[0099] Figure 6 This is a schematic diagram of the structure of an energy storage system according to another embodiment of this application.

[0100] like Figure 6As shown, the energy storage system 1000 includes: a plurality of energy storage units 100 and a plurality of energy storage converters 200, which correspond one-to-one, as well as the equalization control device 500 of the above embodiment.

[0101] Reference Figure 6 Multiple energy storage converters 200 are connected on their AC sides, and the DC side of each energy storage converter 200 is connected to its corresponding energy storage unit 100. The wiring connections between the DC and AC sides of the energy storage converters 200 are shown in [reference needed]. Figure 6 The solid line in the middle, Figure 6 The dashed lines in the diagram represent the control lines of the equalization control device 500 to the energy storage converter 200.

[0102] In one embodiment, the energy storage unit 100 further includes a plurality of switches corresponding one-to-one with a plurality of battery clusters, and the battery clusters are connected to the DC side of the corresponding energy storage inverter 200 through the corresponding switches.

[0103] Based on the energy storage system equalization control method of the above embodiments, this application proposes a computer-readable storage medium.

[0104] In this embodiment, a computer program is stored on a computer-readable storage medium, and when the computer program is executed by a processor, it implements the energy storage system equalization control method of the above embodiment.

[0105] The energy storage system, its equalization control method, apparatus, and storage medium of the present application embodiments can achieve the following beneficial effects:

[0106] 1) Independent battery cluster design: When a battery cluster in the energy storage unit malfunctions, the corresponding switching circuit of the malfunctioning battery cluster can be used to isolate the malfunctioning battery cluster, ensuring that the energy storage converter can still perform dispatching operations.

[0107] 2) By comparing the power difference between battery clusters with the equalization threshold, it can be determined whether equalization should be performed, which can prevent frequent equalization in unnecessary situations and affect scheduling efficiency.

[0108] 3) When the battery cluster equalization is activated, the scheduling power of the scheduling equalization unit is limited to prevent the scheduling current from exceeding the maximum support current of the battery cluster and thus damaging the battery; and the limited power of the scheduling equalization unit will be distributed to other energy storage units to share the burden, ensuring that the overall scheduling power remains unchanged.

[0109] 4) When the power difference between battery clusters is large or the power of a certain battery cluster is low, a power replenishment request can be initiated to replenish the power.

[0110] In the description of this specification, the references to terms such as "some embodiments," "in one example," "exemplarily," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0111] Any process or method description in the flowchart or otherwise herein can be understood as representing a unit, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0112] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are optional and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for equalization control of an energy storage system, characterized in that, The energy storage system includes multiple energy storage units and multiple energy storage converters in a one-to-one correspondence. The AC sides of the multiple energy storage converters are connected to each other, and the DC side of each energy storage converter is connected to a corresponding energy storage unit. The energy storage unit includes multiple battery clusters. The method includes: The battery clusters to be balanced are determined based on the state information of each battery cluster. The target scheduling power is allocated to each of the energy storage units, wherein the scheduling power allocated to the energy storage unit where the battery cluster to be balanced is located does not exceed the maximum power that the battery cluster to be balanced can withstand. Multiple energy storage converters are controlled to schedule the battery clusters in the unbalanced energy storage unit and the battery clusters in the unbalanced energy storage unit according to the scheduling power allocated to the corresponding energy storage unit. The unbalanced energy storage unit refers to an energy storage unit that does not contain the battery cluster to be balanced.

2. The energy storage system equalization control method according to claim 1, characterized in that, The status information of the battery cluster includes the power information of the battery cluster; The step of determining the battery cluster to be balanced based on the state information of each battery cluster includes: For each of the energy storage units, if the difference in charge between the battery clusters in the energy storage unit is greater than the equalization threshold, then in the charging case, the battery cluster with the smallest charge in the energy storage unit is taken as the battery cluster to be equalized, and / or in the discharging case, the battery cluster with the largest charge in the energy storage unit is taken as the battery cluster to be equalized.

3. The energy storage system equalization control method according to claim 2, characterized in that, Before controlling the plurality of energy storage converters to schedule the battery clusters in the unbalanced energy storage unit according to the scheduling power allocated to the corresponding energy storage unit, the method further includes: The switches corresponding to the battery clusters in the unbalanced energy storage unit and the battery clusters to be balanced are controlled to close, and the switches corresponding to the battery clusters in the energy storage unit where the balanced battery cluster is located, excluding the battery cluster to be balanced, are controlled to open; wherein, the energy storage unit also includes multiple switches corresponding one-to-one with multiple battery clusters, and the battery clusters are connected to the DC side of the corresponding energy storage converter through the corresponding switches.

4. The energy storage system equalization control method according to claim 3, characterized in that, The method further includes: When the charge of the battery cluster to be balanced reaches the average charge of the energy storage unit where the battery cluster to be balanced is located, the switches corresponding to the battery clusters other than the battery cluster to be balanced in the energy storage unit where the battery cluster to be balanced is located are closed, and the process returns to determining the battery cluster to be balanced based on the status information of each battery cluster.

5. The energy storage system equalization control method according to claim 3, characterized in that, The status information of the battery clusters also includes normal status and abnormal status; before determining the battery clusters to be balanced based on the status information of each battery cluster, the method further includes: The switch corresponding to the battery cluster that is in normal condition is closed.

6. The energy storage system equalization control method according to claim 2, characterized in that, Before determining the battery cluster to be balanced based on the state information of each battery cluster, the method further includes: When it is determined, based on the status information of each battery cluster, that there is a battery cluster that needs to be recharged, a battery recharge request is initiated.

7. The energy storage system equalization control method according to claim 6, characterized in that, The step of determining which battery clusters need recharging based on the status information of each battery cluster includes: For each energy storage unit, if the difference in charge between battery clusters in the energy storage unit is greater than the charging threshold, or if there is a battery cluster in the energy storage unit with a charge lower than the charging start value, then it is determined that there is a battery cluster that needs charging.

8. The equalization control method for an energy storage system according to any one of claims 1-7, characterized in that, The power allocated to the unbalanced energy storage unit does not exceed the maximum power that a single energy storage unit can withstand.

9. A balancing control device for an energy storage system, characterized in that, The energy storage system includes multiple energy storage units and multiple energy storage converters, with the AC sides of the multiple energy storage converters connected to each other, and the DC side of each energy storage converter connected to multiple battery clusters in the corresponding energy storage unit; the device includes: The determination module is used to determine the battery clusters to be balanced based on the state information of each battery cluster. The allocation module is used to allocate the target scheduling power to each of the energy storage units, wherein the scheduling power allocated to the energy storage unit where the battery cluster to be balanced is located does not exceed the maximum power that the battery cluster to be balanced can withstand. The control module is used to control multiple energy storage converters to schedule the battery clusters in the unbalanced energy storage unit and the battery clusters in the unbalanced energy storage unit according to the scheduling power allocated to the corresponding energy storage unit. The unbalanced energy storage unit refers to an energy storage unit that does not contain the battery clusters to be balanced.

10. An energy storage system, characterized in that, include: Multiple energy storage units and multiple energy storage converters are provided in a one-to-one correspondence. The AC sides of the multiple energy storage converters are connected to each other, and the DC side of the energy storage converters is respectively connected to multiple battery clusters in the corresponding energy storage units. as well as The apparatus according to claim 9.

11. The energy storage system according to claim 10, characterized in that, The energy storage unit also includes multiple switches corresponding to the multiple battery clusters, and the battery clusters are connected to the DC side of the corresponding energy storage converter through the corresponding switches.

12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method according to any one of claims 1-8.

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