A control method of an energy storage system and an energy storage system

Abstract

The application provides a control method and system of an energy storage system. The control method comprises: determining that a first energy storage unit cluster in the plurality of energy storage unit clusters needs to be corrected; and controlling the first energy storage unit cluster to charge or discharge or standby according to a state of charge (SOC) of the first energy storage unit cluster and the fact that the energy storage system is currently in a charging or discharging state, so that the first energy storage unit cluster reaches an SOC correction condition. The control method and system of the energy storage system can control only one energy storage unit cluster that needs to be corrected in the energy storage system to charge or discharge or standby, independently decouple and manage the energy storage unit cluster, do not affect the normal operation of the energy storage system, and can make the energy storage unit cluster quickly reach the SOC correction condition, so that the overall SOC precision of the energy storage system can be improved.

Description

Technical Field

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

[0002] Currently, battery management systems (BMS) estimate battery state of charge (SOC) using the ampere-hour accumulation method. This involves measuring the battery charging or discharging current (A), accumulating it over hours (h), calculating the cumulative charge / discharge capacity (Ah), and adding it to the initial capacity to obtain the current remaining battery capacity.

[0003] However, due to the accuracy issues of devices such as current sensors and conditioning circuits, the inherent errors in current sampling, the time-varying nature of battery operating current, and the possible presence of high and low frequency harmonics, if the current sampling frequency is not high enough, it will lead to sampling deviation, and the accuracy of the BMS in estimating the SOC of the energy storage system will gradually decrease as the system operating time increases.

[0004] In typical energy storage scenarios, the energy storage system is periodically fully charged and discharged, and the voltage at the end of the charge or discharge cycle is used to calibrate the State of Charge (SOC). However, in frequency regulation scenarios, the energy storage system follows automatic generation control (AGC) scheduling commands to perform charging or discharging actions. A single AGC scheduling command is usually within 5 minutes, and the probability of charging and discharging is roughly equal, with few prolonged periods of unidirectional charging or discharging. Therefore, this approach causes the energy storage system to operate in the battery voltage plateau region for extended periods, rarely meeting the SOC calibration conditions for full charge / discharge. This results in the SOC not being calibrated for a long time, leading to increasingly poor SOC accuracy. When SOC accuracy is poor, SOC-based control becomes infeasible, and the SOC value loses its reference value.

[0005] Therefore, how to achieve SOC correction of energy storage systems has become an urgent problem to be solved in the industry. Summary of the Invention

[0006] This application provides a control method and an energy storage system that can achieve online SOC correction of the energy storage system without affecting its normal operation.

[0007] In a first aspect, a control method for an energy storage system is provided. The energy storage system includes multiple energy storage unit clusters, multiple DC converters, and a controller. Each of the multiple energy storage unit clusters corresponds one-to-one with the multiple DC converters, so that the controller can individually control each of the multiple energy storage unit clusters. The method is executed by the controller and includes: determining that a first energy storage unit cluster among the multiple energy storage unit clusters needs to be calibrated; and controlling the first energy storage unit cluster to charge, discharge, or standby according to the state of charge (SOC) of the first energy storage unit cluster and the current charging or discharging state of the energy storage system, so that the first energy storage unit cluster reaches the SOC calibration condition.

[0008] This application uses a controller to determine that the first energy storage unit cluster among multiple energy storage unit clusters needs calibration. Then, based on the State of Charge (SOC) of the first energy storage unit cluster and whether the energy storage system is currently charging or discharging, it controls the first energy storage unit cluster to charge, discharge, or enter standby mode to bring it to the SOC calibration condition. This allows for charging, discharging, or standby control of only one energy storage unit cluster requiring calibration within the energy storage system, achieving independent and decoupled management of the energy storage unit clusters. The energy storage system does not need to be shut down, nor is its normal operation affected, enabling the energy storage unit clusters to quickly reach the SOC calibration condition and achieving online SOC calibration of the energy storage system. Furthermore, the technical solution of this application allows for sequential online SOC calibration of each energy storage unit cluster requiring calibration within the energy storage system, thereby improving the overall SOC accuracy of the energy storage system.

[0009] Alternatively, the energy storage unit cluster can be a battery cluster or other units capable of storing energy.

[0010] Alternatively, the controller can be an energy management system (EMS) or a smart array control unit (SACU).

[0011] Optionally, the SOC correction condition can be a fully charged / fully discharged state.

[0012] In conjunction with the first aspect, in certain implementations of the first aspect, controlling the first energy storage unit cluster to charge, discharge, or standby based on the state of charge (SOC) of the first energy storage unit cluster and the current charging or discharging state of the energy storage system includes: if the SOC of the first energy storage unit cluster is greater than or equal to a first threshold, controlling the first energy storage unit cluster to charge when the energy storage system is in a charging state, and controlling the first energy storage unit cluster to standby until the energy storage system is in a charging state when the energy storage system is in a discharging state; or, if the SOC of the first energy storage unit cluster is less than the first threshold, controlling the first energy storage unit cluster to discharge when the energy storage system is in a discharging state, and controlling the first energy storage unit cluster to standby until the energy storage system is in a discharging state when the energy storage system is in a charging state.

[0013] Optionally, the first threshold can be 50%.

[0014] By determining whether the State of Charge (SOC) of the first energy storage unit cluster is greater than or equal to a first threshold, it is possible to determine how to control the first energy storage unit cluster to quickly reach the SOC correction condition. If the SOC of the first energy storage unit cluster is greater than or equal to the first threshold, when the energy storage system is in a charging state, the first energy storage unit cluster is controlled to charge; when the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a charging state. If the SOC of the first energy storage unit cluster is less than the first threshold, when the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to discharge; when the energy storage system is in a charging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a discharging state. This allows the first energy storage unit cluster to quickly reach the SOC correction condition.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, controlling the first energy storage unit cluster to charge includes: controlling the first energy storage unit cluster to charge at a power greater than that in the normal operating mode of the energy storage system, where the charging power in the normal operating mode refers to the charging power when the energy storage system allocates power according to the SOC of the plurality of energy storage unit clusters; or, controlling the first energy storage unit cluster to discharge includes: controlling the first energy storage unit cluster to discharge at a power greater than that in the normal operating mode of the energy storage system, where the discharge power in the normal operating mode refers to the discharge power when the energy storage system allocates power according to the SOC of the plurality of energy storage unit clusters.

[0016] By controlling the first energy storage unit cluster to charge at a power greater than that of the energy storage system under normal operating conditions, or by controlling the first energy storage unit cluster to discharge at a power greater than that of the energy storage system under normal operating conditions, the first energy storage unit cluster can be charged or discharged at a power greater than that of the normal operating conditions, thereby quickly reaching the SOC correction condition.

[0017] In conjunction with the first aspect, in some implementations of the first aspect, controlling the first energy storage unit cluster to charge includes: controlling the first energy storage unit cluster to charge at the maximum charging power of the energy storage system, the maximum charging power being greater than the charging power in the normal operating mode, and being the maximum power calculated by the battery management system (BMS) of the energy storage system; or, controlling the first energy storage unit cluster to discharge includes: controlling the first energy storage unit cluster to discharge at the maximum discharge power of the energy storage system, the maximum discharge power being greater than the discharge power in the normal operating mode, and being the maximum power calculated by the battery management system (BMS) of the energy storage system.

[0018] By controlling the first energy storage unit cluster to charge at the maximum charging power calculated by the battery management system (BMS) of the energy storage system, or by controlling the first energy storage unit cluster to discharge at the maximum discharging power calculated by the BMS of the energy storage system, the first energy storage unit cluster can be charged or discharged at the maximum power calculated by the BMS, thereby quickly reaching the SOC correction condition.

[0019] In conjunction with the first aspect, in some implementations of the first aspect, determining that the first energy storage unit cluster among the plurality of energy storage unit clusters needs calibration includes: receiving the cumulative operating time Tr of the first energy storage unit cluster since the last SOC calibration time point and the cumulative non-operating time Td of the first energy storage unit cluster since the last SOC calibration time point sent by the BMS of the energy storage system; and determining that the first energy storage unit cluster needs calibration based on the Tr and the Td.

[0020] By receiving the cumulative operating time Tr and the cumulative non-operating time Td of the first energy storage unit cluster since the last SOC correction time point sent by the BMS of the energy storage system, the controller can determine that the first energy storage unit cluster needs correction based on Tr and Td, thereby controlling the charging and discharging power of the first energy storage unit cluster and enabling the first energy storage unit cluster to quickly reach the SOC correction condition.

[0021] In conjunction with the first aspect, in some implementations of the first aspect, determining that the first energy storage unit cluster needs calibration based on the Tr and the Td includes: if the Tr is greater than or equal to the cumulative operating time Ts that requires calibration, then the first energy storage unit cluster is determined to be an energy storage unit cluster that requires calibration; or, if the Td is greater than or equal to the cumulative non-operating time Tp that requires calibration, then the energy storage unit cluster is determined to be an energy storage unit cluster that requires calibration.

[0022] By determining whether Tr is greater than or equal to Ts, or whether Td is greater than or equal to Tp, it is possible to determine whether the energy storage unit cluster is an energy storage unit cluster that needs to be calibrated, so as to determine whether to control the charging, discharging or standby operating mode of the energy storage unit cluster separately.

[0023] In conjunction with the first aspect, in some implementations of the first aspect, when multiple energy storage unit clusters are energy storage unit clusters that need to be calibrated, the first energy storage unit cluster that needs to be calibrated is determined according to the priority order.

[0024] By determining the first energy storage unit cluster according to priority order among multiple energy storage unit clusters that need to be calibrated, the controller can prioritize the charging, discharging, or standby operating mode of the first energy storage unit cluster.

[0025] In conjunction with the first aspect, in some implementations of the first aspect, when the first energy storage unit cluster reaches the SOC correction condition, the BMS of the energy storage system is notified to perform SOC correction on the first energy storage unit cluster.

[0026] When the first energy storage unit cluster reaches the SOC correction condition, the BMS of the energy storage system is notified to perform SOC correction on the first energy storage unit cluster, thereby realizing the SOC correction of the first energy storage unit cluster.

[0027] In conjunction with the first aspect, in some implementations of the first aspect, a notification sent by the BMS indicating that the SOC correction of the first energy storage unit cluster is complete is received; the first energy storage unit cluster is controlled to charge, discharge, or standby in the normal operating mode of the energy storage system, wherein the normal operating mode refers to the mode in which the energy storage system allocates power according to the SOC of the multiple energy storage unit clusters.

[0028] After receiving a notification from the BMS that the SOC correction of the first energy storage unit cluster is complete, the controller can control the first energy storage unit cluster to charge, discharge, or standby in the normal operating mode of the energy storage system. This allows the controller to terminate the individual control of the first energy storage unit cluster, enabling the controller to control the charging, discharging, or standby of other energy storage unit clusters that need correction, so that the other energy storage unit clusters that need correction can reach the SOC correction conditions.

[0029] Secondly, an energy storage system is provided, comprising multiple energy storage unit clusters, multiple DC converters, a controller, and a battery management system (BMS). Each energy storage unit cluster corresponds one-to-one with one of the multiple DC converters, enabling the controller to individually control each of the multiple energy storage unit clusters. The BMS is used to acquire the state of charge (SOC) of the multiple energy storage unit clusters and send the SOC of the multiple energy storage unit clusters to the controller. The controller is used to determine that a first energy storage unit cluster among the multiple energy storage unit clusters needs calibration. The controller is also used to control the first energy storage unit cluster to charge, discharge, or standby based on its SOC and whether the energy storage system is currently in a charging or discharging state, so that the first energy storage unit cluster reaches the SOC calibration condition.

[0030] This application uses a controller to determine that the first energy storage unit cluster among multiple energy storage unit clusters needs calibration. Then, based on the state of charge (SOC) of the first energy storage unit cluster and whether the energy storage system is currently charging or discharging, it controls the first energy storage unit cluster to charge, discharge, or enter standby mode to bring it to the SOC calibration condition. This allows for charging, discharging, or standby control of only one energy storage unit cluster requiring calibration within the energy storage system, achieving independent and decoupled management of the energy storage unit clusters. The energy storage system does not need to be shut down, nor is its normal operation affected, enabling the energy storage unit clusters to quickly reach the SOC calibration condition and achieving online SOC calibration of the energy storage system. Furthermore, the technical solution of this application allows for sequential online SOC calibration of each energy storage unit cluster requiring calibration within the energy storage system, thereby improving the overall SOC accuracy of the energy storage system.

[0031] Alternatively, the energy storage unit cluster can be a battery cluster or other units capable of storing energy.

[0032] Alternatively, the controller can be an EMS or a SACU.

[0033] Optionally, the SOC correction condition can be a fully charged / fully discharged state.

[0034] In conjunction with the second aspect, in some implementations of the second aspect, controlling the first energy storage unit cluster to charge, discharge, or standby based on the state of charge (SOC) of the first energy storage unit cluster and the current charging or discharging state of the energy storage system includes: if the SOC of the first energy storage unit cluster is greater than or equal to a first threshold, controlling the first energy storage unit cluster to charge when the energy storage system is in a charging state, and controlling the first energy storage unit cluster to standby until the energy storage system is in a charging state when the energy storage system is in a discharging state; or, if the SOC of the first energy storage unit cluster is less than the first threshold, controlling the first energy storage unit cluster to discharge when the energy storage system is in a discharging state, and controlling the first energy storage unit cluster to standby until the energy storage system is in a discharging state when the energy storage system is in a charging state.

[0035] Optionally, the first threshold can be 50%.

[0036] By determining whether the State of Charge (SOC) of the first energy storage unit cluster is greater than or equal to a first threshold, it is possible to determine how to control the first energy storage unit cluster to quickly reach the SOC correction condition. If the SOC of the first energy storage unit cluster is greater than or equal to the first threshold, when the energy storage system is in a charging state, the first energy storage unit cluster is controlled to charge; when the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a charging state. If the SOC of the first energy storage unit cluster is less than the first threshold, when the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to discharge; when the energy storage system is in a charging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a discharging state. This allows the first energy storage unit cluster to quickly reach the SOC correction condition.

[0037] In conjunction with the second aspect, in some implementations of the second aspect, controlling the first energy storage unit cluster to charge includes: controlling the first energy storage unit cluster to charge at a power greater than that in the normal operating mode of the energy storage system, where the charging power in the normal operating mode refers to the charging power when the energy storage system allocates power according to the SOC of multiple energy storage unit clusters; or, controlling the first energy storage unit cluster to discharge includes: controlling the first energy storage unit cluster to discharge at a power greater than that in the normal operating mode of the energy storage system, where the discharge power in the normal operating mode refers to the discharge power when the energy storage system allocates power according to the SOC of multiple energy storage unit clusters.

[0038] By controlling the first energy storage unit cluster to charge at a power greater than that of the energy storage system under normal operating conditions, or by controlling the first energy storage unit cluster to discharge at a power greater than that of the energy storage system under normal operating conditions, the first energy storage unit cluster can be charged or discharged at a power greater than that of the normal operating conditions, thereby quickly reaching the SOC correction condition.

[0039] In conjunction with the second aspect, in some implementations of the second aspect, controlling the first energy storage unit cluster to charge includes: controlling the first energy storage unit cluster to charge at the maximum charging power of the energy storage system, wherein the maximum charging power is greater than the charging power in the normal operating mode and is the maximum power calculated by the BMS; or, controlling the first energy storage unit cluster to discharge includes: controlling the first energy storage unit cluster to discharge at the maximum discharge power of the energy storage system, wherein the maximum discharge power is greater than the discharge power in the normal operating mode and is the maximum power calculated by the BMS.

[0040] By controlling the first energy storage unit cluster to charge at the maximum charging power calculated by the battery management system (BMS) of the energy storage system, or by controlling the first energy storage unit cluster to discharge at the maximum discharging power calculated by the BMS of the energy storage system, the first energy storage unit cluster can be charged or discharged at the maximum power calculated by the BMS, thereby quickly reaching the SOC correction condition.

[0041] In conjunction with the second aspect, in certain implementations of the second aspect, determining that the first energy storage unit cluster among the plurality of energy storage unit clusters needs calibration includes: the BMS is further configured to send the cumulative operating time Tr of the first energy storage unit cluster since the last SOC calibration time and the cumulative non-operating time Td of the first energy storage unit cluster since the last SOC calibration time to the controller; the controller is further configured to receive the Tr and the Td sent by the BMS of the energy storage system; the controller is further configured to determine that the first energy storage unit cluster needs calibration based on the Tr and the Td.

[0042] By receiving the cumulative operating time Tr and the cumulative non-operating time Td of the first energy storage unit cluster since the last SOC calibration time from the BMS of the energy storage system, the controller can determine that the first energy storage unit cluster needs calibration based on Tr and Td, thereby controlling the charging and discharging power of the first energy storage unit cluster and enabling the first energy storage unit cluster to quickly reach SOC calibration.

[0043] In conjunction with the second aspect, in some implementations of the second aspect, determining that the first energy storage unit cluster needs calibration based on the Tr and the Td includes: if the Tr is greater than or equal to the cumulative operating time Ts that requires calibration, then the first energy storage unit cluster is determined to be an energy storage unit cluster that requires calibration; or, if the Td is greater than or equal to the cumulative non-operating time Tp that requires calibration, then the energy storage unit cluster is determined to be an energy storage unit cluster that requires calibration.

[0044] By determining whether Tr is greater than or equal to Ts, or whether Td is greater than or equal to Tp, it is possible to determine whether the energy storage unit cluster is an energy storage unit cluster that needs to be calibrated, so as to determine whether to control the charging, discharging or standby operating mode of the energy storage unit cluster separately.

[0045] In conjunction with the second aspect, in some implementations of the second aspect, when multiple energy storage unit clusters are energy storage unit clusters that need to be calibrated, the controller determines the first energy storage unit cluster that needs to be calibrated according to the priority order.

[0046] By determining the first energy storage unit cluster according to priority order among multiple energy storage unit clusters that need to be calibrated, the controller can prioritize the charging, discharging, or standby operating mode of the first energy storage unit cluster.

[0047] In conjunction with the second aspect, in some implementations of the second aspect, the controller is further configured to notify the BMS of the energy storage system to perform SOC correction on the first energy storage unit cluster when the first energy storage unit cluster reaches the SOC correction condition.

[0048] When the first energy storage unit cluster reaches the SOC correction condition, the BMS of the energy storage system is notified to perform SOC correction on the first energy storage unit cluster, thereby realizing the SOC correction of the first energy storage unit cluster.

[0049] In conjunction with the second aspect, in some implementations of the second aspect, the controller is further configured to receive a notification from the BMS indicating that the SOC correction of the first energy storage unit cluster is complete; the controller is further configured to control the first energy storage unit cluster to charge, discharge, or standby in the normal operating mode of the energy storage system, wherein the normal operating mode refers to the mode in which the energy storage system allocates power according to the SOC of the plurality of energy storage unit clusters.

[0050] After receiving a notification from the BMS that the SOC correction of the first energy storage unit cluster is complete, the controller can control the first energy storage unit cluster to charge, discharge, or standby in the normal operating mode of the energy storage system. This allows the controller to terminate the individual control of the first energy storage unit cluster, enabling the controller to control other energy storage unit clusters that need correction to charge, discharge, or standby, so that the other energy storage unit clusters that need correction can reach the SOC correction conditions. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of an energy storage system provided in this application.

[0052] Figure 2 This is an architecture diagram of an energy storage system provided in this application.

[0053] Figure 3 This is another architecture diagram of an energy storage system provided in this application.

[0054] Figure 4 This is another architecture diagram of an energy storage system provided in this application.

[0055] Figure 5 This is an architecture diagram of an energy storage system provided in this application.

[0056] Figure 6 This is a schematic diagram of a control method for an energy storage system provided in this application.

[0057] Figure 7 This is a schematic flowchart of a control method for an energy storage system provided in this application. Detailed Implementation

[0058] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0059] Figure 1 This is a schematic diagram of an energy storage system provided in this application.

[0060] The energy storage system contains at least one cluster of energy storage units, such as Figure 1 The battery clusters shown are 1 to m, where m can be a natural number greater than 0. In practical applications, the number of battery clusters can be flexibly adjusted according to the energy storage capacity. If the energy storage capacity is large, the number of battery clusters can be increased appropriately, and if the energy storage capacity is small, the number of battery clusters can be reduced appropriately.

[0061] It should be understood that, Figure 1 In the energy storage system shown, the energy storage unit cluster can be presented in the form of a battery cluster or in the form of other units capable of storing energy; this application does not limit this. For ease of description, this application uses the form of a battery cluster to describe the technical solution of this application.

[0062] Each battery cluster consists of at least two energy storage systems (ESS) connected in series, such as Figure 1The system comprises battery modules 1 through j, where j can be a natural number greater than or equal to 2. Each energy storage module (ESS) consists of several energy storage elements connected in series or parallel, forming the smallest energy storage and management unit. To enable the detection and control of the energy storage system, each energy storage module and battery cluster is equipped with a battery management system (BMS) to monitor battery information such as SOC, temperature, and current, and to interact with the upper-level EMS or SACU in real time, thereby achieving effective management and control of the entire battery energy storage system.

[0063] In this embodiment, each battery cluster is managed in a decoupled manner, meaning each battery cluster can be controlled independently. When at least one battery cluster among multiple battery clusters requires SOC correction, that battery cluster requiring SOC correction is controlled independently without affecting the normal operation of the energy storage system.

[0064] The following text will first combine Figures 2 to 5 The energy storage system provided in this application is described.

[0065] Figure 2 This is an architecture diagram of an energy storage system provided in this application.

[0066] Specifically, such as Figure 2 As shown, the battery module is arranged according to Figure 1 The battery clusters are connected in series as shown, and then connected to one port of a bidirectional DC converter. The other port of the bidirectional DC converter is connected to a DC bus.

[0067] exist Figure 2 The architecture shown includes a total of m battery clusters, each of which is connected to a bidirectional DC converter and a DC bus. The battery clusters exchange energy with the DC bus through the bidirectional DC converter.

[0068] It should be understood that, Figure 2 In the architecture shown, by setting each battery cluster to be connected to a bidirectional DC converter, the battery clusters can be controlled independently, thereby achieving independent decoupled management of the operation of each battery cluster. This also effectively avoids the bottleneck effect between battery clusters and ensures the normal operation of the energy storage system.

[0069] After m battery clusters are connected in series with m DC converters in a one-to-one correspondence, they will converge to Figure 2The diagram shows one port of a DC combiner cabinet. The other port of the combiner cabinet is connected to the DC side of n power conversion systems (PCSs), where n is a natural number greater than 0. The AC side of the n PCSs is connected to the low-voltage side of a transformer, and the high-voltage side of the transformer is connected to the power grid.

[0070] The combiner cabinet can collect and distribute the current on the DC bus. When the power of the DC converter and the PCS unit is not matched, the overall power of the AC and DC sides can be matched by configuring the appropriate number of units.

[0071] It should be understood that Figure 2 The combined switch shown is not mandatory. When a combined switch is not available, this application can also achieve the equivalent function of a combined switch by connecting DC buses in parallel, etc., and this application does not limit this.

[0072] It should also be understood that Figure 2 The n PCS units shown can be connected in parallel to the low-voltage side of a two-winding transformer, or they can be divided into two or more groups and connected in parallel to multiple low-voltage busbars of a three-winding double-split transformer or other multi-winding transformers. Furthermore, the transformer is not a strictly constrained component in this application; in low-voltage grid connection scenarios, a transformer may not be necessary.

[0073] To aid in understanding the technical solution of this application, this application uses a battery module voltage of 57.6V and a series connection of 20 battery modules as an example rather than a limitation, to further illustrate the technical solution of this application. When the battery module voltage is 57.6V and the series connection of 20 battery modules is 20, the battery cluster port voltage is 57.6 × 20 = 1152Vdc.

[0074] It should be understood that after calculating the battery cluster port voltage, a matching DC-DC converter should be selected based on the magnitude of the port voltage. For example, when the calculated battery cluster port voltage is 1152Vdc, the matching DC-DC converter is a bidirectional DC / DC converter, matching voltages from 1000Vdc to 1500Vdc, and matching the battery cluster port voltage with AC voltages from 380Vac to 800Vac.

[0075] It should also be understood that, in order to achieve high-efficiency power conversion, the DC converter in the embodiments of this application typically uses a non-isolated circuit topology. As an example and not a limitation, the non-isolated circuit may include a flying capacitor multilevel circuit, a three-level boost circuit, a four-transistor BUCK-BOOST circuit, etc., and this application does not limit it in this regard.

[0076] It should also be understood that the PCS described in this application is a bidirectional DC / AC converter, which can employ neutral point clamped T-type three-level circuits, neutral point clamped (NPC) circuits, active neutral point clamped (ANPC) circuits, flying capacitor multilevel circuits, etc. Furthermore, since the port voltage of the energy storage element varies with the energy storage capacity, and the battery cluster port voltage is a wide-range output voltage, the DC converter or PCS is typically designed with a wide-range input / output capability to match the varying range of the battery cluster port voltage.

[0077] In this application, the power switching devices of the DC converter and PCS used in the embodiments can be either MOSFETs or IGBTs, by way of example and not limitation.

[0078] Figure 3 This is a schematic diagram of another energy storage system architecture provided in this application.

[0079] and Figure 2 The architecture shown is different. Figure 3 The other ends of the m DC converters shown are connected to the DC side of the m PCS respectively. The AC sides of the m PCS are collected to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the power grid. There is a one-to-one correspondence between the DC converters and PCS, and the individual power of the DC converters and PCS is matched. In power dispatch control, the output power of the PCS can be directly controlled. The DC converters operate in voltage source mode.

[0080] Figure 4 This is a schematic diagram of the architecture of another energy storage system provided in this application.

[0081] exist Figure 4 The architecture shown consists of a total of m battery clusters, where m is a natural number greater than 0. Each battery cluster is connected to a PCS (Power Control System). The AC sides of the m PCS converge to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the power grid.

[0082] Figure 4 The architecture shown allows for independent control of battery clusters, enabling decoupled management of individual cluster operation and effectively avoiding bottleneck effects between clusters. In power dispatch control, the charging / discharging of battery clusters can be controlled by adjusting the output power of the PCS.

[0083] Figure 5 This is a schematic diagram of another energy storage system architecture provided in this application.

[0084] It should be understood that, Figure 5In the architecture shown, each battery cluster is connected to a DC converter, and the other end of each cluster's DC converter is connected to the DC side of a centralized PCS. The AC side of the centralized PCS is connected to one side of a transformer, and the other side of the transformer is connected to the power grid. Figure 5 In the architecture shown, although multiple battery clusters are connected to a single PCS, the DC converter connected in series with the battery clusters can decouple the battery clusters, thereby enabling independent charging, discharging, or standby control.

[0085] It should be understood that in the energy storage system architecture shown above, transformers are not necessary. In scenarios such as low-voltage distribution network access, where the grid voltage level is the same as the PCS output voltage level, transformers may not be required.

[0086] The above Figures 2 to 5 A schematic diagram illustrating the specific architecture of four energy storage systems provided in this application is shown. It should be understood that, in the embodiments of this application, the energy storage system may include the following components: multiple energy storage unit clusters, multiple DC converters, a controller, and a battery management system (BMS). Each of the multiple energy storage unit clusters corresponds one-to-one with a single DC converter, enabling the controller to individually control each of the multiple energy storage unit clusters.

[0087] The battery management system (BMS) is used to obtain the state of charge (SOC) of multiple energy storage cell clusters and send the SOC of multiple energy storage cell clusters to the controller.

[0088] The controller can be an EMS or an SACU, and it is used to determine that the first energy storage unit cluster among multiple energy storage unit clusters needs calibration. Based on the SOC of the first energy storage unit cluster and whether the energy storage system is currently charging or discharging, the controller controls the first energy storage unit cluster to charge, discharge, or standby mode so that the first energy storage unit cluster reaches the SOC calibration condition. The SOC calibration condition can be a fully charged / fully discharged state.

[0089] The following will combine Figure 6 and Figure 7 The control method for the energy storage system provided in this application is described.

[0090] Figure 6 The diagram shows a control method for an energy storage system provided in this application. The main body executing this method is the controller in the energy storage system. The controller can be an EMS or an SACU, and this application does not limit it.

[0091] S610, determine that the first energy storage unit cluster among the multiple energy storage unit clusters needs to be calibrated;

[0092] S620, based on the state of charge (SOC) of the first energy storage unit cluster and the current charging or discharging state of the energy storage system, control the first energy storage unit cluster to charge, discharge, or standby, so that the first energy storage unit cluster reaches the SOC correction condition.

[0093] It should be understood that in the above technical solution, the controller determines the first energy storage unit cluster that needs to be calibrated among the multiple energy storage units, and obtains the state of charge of the first energy storage unit cluster and whether the energy storage system is in a charging or discharging state, so as to individually control the charging, discharging or standby of the first energy storage unit cluster, thereby enabling the first energy storage unit cluster to reach the SOC calibration condition.

[0094] The specific plan is as follows:

[0095] #a: If the SOC of the first energy storage unit cluster is greater than or equal to the first threshold, and the energy storage system is in a charging state, the controller controls the first energy storage unit cluster to charge; and when the energy storage system is in a discharging state, the controller controls the first energy storage unit cluster to standby until the energy storage system is in a charging state.

[0096] #b: If the SOC of the first energy storage unit cluster is less than the first threshold, when the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to discharge; when the energy storage system is in a charging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a discharging state.

[0097] Optionally, the first threshold can be 50%.

[0098] It should be understood that the above technical solution enables the first energy storage unit cluster to quickly reach the SOC correction condition.

[0099] For example, if it is necessary to control the first energy storage unit cluster to charge, the controller controls the first energy storage unit cluster to charge at a power greater than that in the normal operating mode of the energy storage system; or, if it is necessary to control the first energy storage unit cluster to discharge, the controller controls the first energy storage unit cluster to discharge at a power greater than that in the normal operating mode of the energy storage system.

[0100] It should be understood that by controlling the first energy storage unit cluster to charge at a power greater than that of the energy storage system in normal operating mode, or by controlling the first energy storage unit cluster to discharge at a power greater than that of the energy storage system in normal operating mode, the first energy storage unit cluster can be charged or discharged at a power greater than that of the normal operating mode, thereby quickly reaching the SOC correction condition.

[0101] It should be understood that the discharge or charging power under this normal operating mode refers to the discharge or charging power of the energy storage system when the power is allocated according to the SOC of the multiple energy storage unit clusters.

[0102] If the controller controls the first energy storage unit cluster to charge, the first energy storage unit cluster charges at the maximum charging power of the energy storage system, which is greater than the charging power in normal operating mode and is the maximum power calculated by the battery management system (BMS) of the energy storage system; or, if the controller controls the first energy storage unit cluster to discharge, the first energy storage unit cluster discharges at the maximum discharge power of the energy storage system, which is greater than the discharge power in normal operating mode and is the maximum power calculated by the battery management system (BMS) of the energy storage system.

[0103] It should be understood that the controller can receive the cumulative operating time Tr of the first energy storage unit cluster since the last SOC calibration time and the cumulative non-operating time Td of the first energy storage unit cluster since the last SOC calibration time from the BMS of the energy storage system, and determine whether the first energy storage unit cluster needs calibration based on the Tr and the Td.

[0104] Specifically, if Tr is greater than or equal to the cumulative operating time Ts that requires correction, then the first energy storage unit cluster is determined to be an energy storage unit cluster that requires correction; or, if Td is greater than or equal to the cumulative non-operation time Tp that requires correction, then the energy storage unit cluster is determined to be an energy storage unit cluster that requires correction.

[0105] When multiple energy storage cell clusters require calibration, the controller determines the first cluster to require calibration based on priority. This priority order is determined by the detection order; for example, the earlier a cell cluster requiring SC calibration is detected, the higher its priority.

[0106] Optionally, when the first energy storage unit cluster reaches the SOC correction condition, the controller will notify the BMS of the energy storage system to perform SOC correction on the first energy storage unit cluster.

[0107] Optionally, the controller may receive a notification from the BMS indicating that the SOC correction of the first energy storage unit cluster is complete, or it may control the first energy storage unit cluster to charge, discharge, or standby in the normal operating mode of the energy storage system.

[0108] Through the above technical solution, this application can achieve individual control of the charging, discharging, or standby of the first energy storage unit cluster, so that the first energy storage unit cluster reaches the SOC correction condition. It can control the charging, discharging, or standby of only one energy storage unit cluster requiring correction within the energy storage system, achieving independent and decoupled management of the energy storage unit cluster. The energy storage system does not need to be shut down, nor is its normal operation affected, allowing the energy storage unit cluster to quickly reach the SOC correction condition, thus realizing online SOC correction of the energy storage system. Furthermore, the technical solution of this application can perform online SOC correction on each energy storage unit cluster requiring correction in turn, thereby improving the overall SOC accuracy of the energy storage system.

[0109] Figure 7 This is a schematic flowchart of a control method for an energy storage system according to one embodiment of this application, and also a [details about the method]. Figure 6 A further detailed description of the control method shown herein, which may include steps S701-S714. In the following description, ... Figure 2 The architecture shown is used as an example for explanation.

[0110] S701, the BMS monitors the operating status of each battery cluster, records the time Ti of the last SOC calibration for each battery cluster, as well as the cumulative operating time Tr and the cumulative non-operating time Td.

[0111] It should be understood that cumulative operating time refers to the cumulative operating time of the battery cluster since the last SOC calibration; cumulative non-operating time refers to the cumulative non-operating time of the battery cluster since the last SOC calibration. Non-operating means the battery cluster is in a power-off state.

[0112] S702, BMS determines whether Tr is greater than or equal to the preset cumulative running correction time Ts.

[0113] If not, proceed to step S703; if yes, proceed to step S704.

[0114] It should be understood that if Tr is greater than or equal to the cumulative operating time Ts required for calibration, it means that the battery cluster has reached the preset condition for cumulative operating time requiring calibration, and the battery cluster needs to be calibrated. The preset condition for cumulative operating time requiring calibration is that the cumulative operating time of the battery cluster is greater than the preset Ts.

[0115] S703, BMS determines whether Td is greater than or equal to the preset cumulative non-running time Tp that needs to be corrected.

[0116] If not, proceed to step S701; if yes, proceed to step S704.

[0117] It should be understood that if Td is greater than or equal to the cumulative non-operation time Tp that requires calibration, it means that the battery cluster has reached the preset condition for cumulative operation requiring calibration, and the battery cluster needs to be calibrated. The preset condition for cumulative operation requiring calibration is that the cumulative non-operation time of the battery cluster is greater than the preset Td.

[0118] S704 If the BMS determines that multiple battery clusters need to be calibrated, the EMS will prioritize each cluster.

[0119] It should be understood that the BMS determines that a battery cluster needs to be corrected based on Tr≥Ts or Td≥Tp.

[0120] It should also be understood that if the BMS determines that multiple battery clusters require calibration, the EMS prioritizes these clusters based on the order in which they were detected. The earlier a battery cluster is detected requiring calibration, the higher its priority.

[0121] Optionally, the execution entity in step S704 can also be SACU.

[0122] S705, BMS determines whether the SOC of the battery cluster that needs correction is greater than the first threshold.

[0123] If not, proceed to step S706; if yes, proceed to step S711.

[0124] It should be understood that when the BMS determines that the SOC of the battery cluster requiring correction is greater than the first threshold, it means that the current state of the battery cluster is more likely to achieve full charge than full discharge. Therefore, the next step is to make the battery cluster reach full charge as soon as possible to meet the SOC correction conditions. When the BMS determines that the SOC of the battery cluster requiring correction is not greater than the first threshold, it means that the current state of the battery cluster is more likely to achieve full discharge than full charge. Therefore, the next step is to make the battery cluster reach full discharge as soon as possible to meet the SOC correction conditions.

[0125] It should be understood that the criterion used in this embodiment for determining whether the battery cluster meets the SOC correction conditions is whether the battery cluster's SOC is in a fully charged / fully discharged state.

[0126] Optionally, the first threshold can be 50%.

[0127] Alternatively, the SOC correction condition can also be based on whether the battery cluster voltage is in a fully charged / fully discharged state.

[0128] The S706 EMS controller monitors whether the energy storage system is currently charging or discharging.

[0129] It should be understood that the EMS controller monitors whether the energy storage system is currently charging or discharging. This allows the EMS to determine in step S707 whether the energy storage system is discharging, and thus adjust the state of the battery clusters accordingly. The state of the battery clusters includes participating in discharging and standby.

[0130] Optionally, the EMS can determine whether the energy storage system is currently charging or discharging by judging whether the power command P* received from the upper-level scheduling or local control is positive. A positive P* indicates that the system is discharging, while a negative P* indicates that the system is charging.

[0131] Optionally, the execution entity of step S706 can also be SACU.

[0132] S707, EMS determines whether the energy storage system is in a discharging state.

[0133] If not, proceed to step S708; if yes, proceed to step S709.

[0134] It should be understood that the EMS controller monitors whether the energy storage system is currently in a discharging state, and determines the next operation of the battery cluster that needs to be corrected. That is, through different operations, the battery cluster can reach a fully discharged state as soon as possible, so as to achieve the SOC correction condition of the battery cluster.

[0135] Optionally, the execution entity of step S707 can also be SACU.

[0136] S708, the battery clusters that require calibration under EMS control are in standby mode and do not participate in energy storage scheduling control.

[0137] It should be understood that when the BMS determines that the SOC of a battery cluster requiring correction is not greater than the first threshold, achieving full discharge is easier than full charge for that cluster. Therefore, the cluster needs to be discharged to reach full discharge. Thus, when the EMS determines that the energy storage system is not in a discharging state, the cluster requiring correction should be put into standby mode and not participate in energy storage scheduling control. This prevents the SOC of the cluster from increasing, which would hinder achieving full discharge.

[0138] Alternatively, the battery cluster to be calibrated can be put into standby mode by putting the DC inverter connected to the battery cluster into standby mode.

[0139] Alternatively, if the calibration speed is not a priority, the battery cluster that needs calibration can continue to operate in the same power distribution mode as other battery clusters during charging / discharging until the SOC calibration condition is met.

[0140] Optionally, the execution entity of step S708 can also be SACU.

[0141] S709, EMS controls the battery clusters that need correction to participate in discharge within the constraints of BMS until the SOC correction condition is reached.

[0142] It should be understood that when the BMS determines that the SOC of the battery cluster requiring correction is not greater than the first threshold, achieving full discharge is easier than full charge. Therefore, the battery cluster needs to be discharged to reach full discharge. Thus, when the EMS determines that the energy storage system is in a discharge state, it should allow the battery cluster requiring correction to participate in the discharge. Furthermore, by controlling the discharge within the constraints of the BMS—that is, discharging at the maximum discharge rate allowed by the BMS (correction mode)—it is beneficial for the battery cluster to reach full discharge as quickly as possible, thereby meeting the SOC correction conditions.

[0143] It should also be understood that the calibration mode refers to the charging power P = P1max of the DC converter connected to the battery cluster to be calibrated controlled by the EMS, where P1max is the maximum charging power that can be operated under the constraints of the current limiting table or power limiting table of the battery cluster to be calibrated provided by the BMS, until the battery cluster to be calibrated meets the SOC calibration conditions.

[0144] Alternatively, if the calibration speed is not a priority, the battery cluster that needs calibration can continue to operate in the same power distribution mode (normal mode) as other battery clusters during charging / discharging until the SOC calibration condition is met.

[0145] It should be understood that in normal mode, the power allocation mechanism for charging or discharging is as follows: the remaining power P*-P1max after allocating power to the battery cluster that needs to be calibrated is allocated by the other m-1 DC converters in normal charging or discharging mode.

[0146] Specifically, during charging, battery clusters with higher State of Charge (SOC) receive less power, while those with lower SOC receive more power, aiming to achieve a balanced charging effect. If the total power is P*, and the battery cluster requiring correction is cluster 1, then its charging power is P1max. For the other battery clusters (i.e., clusters 2 to m), the charging power of the i-th battery cluster is... Where SOCi is the SOC of the i-th battery cluster, 2≤i≤m. For example, when there are three battery clusters, assuming battery cluster 1 is the cluster that needs correction, and the SOC ratio of battery cluster 2 to battery cluster 3 is 4:6, then during charging power allocation, the power allocated to battery cluster 2 is (P*-P1max)×0.6, and the power allocated to battery cluster 3 is (P*-P1max)×0.4. During discharging, battery clusters with larger SOCs receive more power, and battery clusters with smaller SOCs receive less power, in order to achieve a balanced control effect of simultaneous discharge. If the total power is P*, and the battery cluster that needs correction is the 1st cluster, then the discharge power of the 1st battery cluster is P1max. Except for the battery cluster that needs correction, the discharge power of the i-th battery cluster in the other battery clusters (i.e., clusters 2 to m) is... Where SOCi is the SOC of the i-th battery cluster, 2≤i≤m. For example, when there are three battery clusters, assuming that battery cluster 1 is the battery cluster that needs to be corrected, and the SOC ratio of battery cluster 2 to battery cluster 3 is 4:6, then when discharging power, the power allocated to battery cluster 2 is (P*-P1max)×0.4, and the power allocated to battery cluster 3 is (P*-P1max)×0.6.

[0147] It should also be understood that for n PCS, the power can be evenly distributed among the PCS according to P*, that is, the power allocated to each PCS is P* / n.

[0148] Optionally, the execution entity of step S709 can also be SACU.

[0149] After the S710 BMS completes the SOC calibration, it informs the EMS so that the calibrated battery clusters can participate in normal charging, discharging, or standby operation.

[0150] It should be understood that before the battery cluster that needs to be calibrated is calibrated, in order to bring the battery cluster to the SOC calibration condition as soon as possible, the battery cluster needs to be controlled to charge / discharge in calibration mode, that is, to charge / discharge using the maximum operating power / current under BMS constraints, instead of operating in normal mode (i.e., the operating mode that allocates power based on SOC); after the battery cluster completes SOC calibration, it needs to be restored to normal charging or discharging or standby operation, that is, to operate in the power allocation mode based on SOC.

[0151] Optionally, in step S710, after the BMS completes the SOC calibration, it can also inform the SACU so that the calibrated battery clusters can participate in normal charging, discharging, or standby operation.

[0152] The S711 EMS controller monitors whether the energy storage system is currently charging or discharging.

[0153] It should be understood that the EMS controller monitors whether the energy storage system is currently charging or discharging. This allows the EMS to determine whether the energy storage system is charging in step S712, and thus adjust the state of the battery clusters accordingly. The state of the battery clusters includes both charging and standby modes.

[0154] Optionally, the EMS can determine whether the energy storage system is currently charging or discharging by judging whether the power command P* received from the upper-level dispatching, such as a remote terminal unit (RTU), or local control, such as a supervisory control and data acquisition (SCADA) system, is negative. A positive P* indicates that the system is discharging, while a negative P* indicates that the system is charging.

[0155] Optionally, the execution entity of step S711 can also be SACU.

[0156] S712, EMS determines whether the energy storage system is charging.

[0157] If not, proceed to step S713; if yes, proceed to step S714.

[0158] It should be understood that the EMS controller monitors whether the energy storage system is currently charging and determines the next operation of the battery cluster that needs to be calibrated. That is, through different operations, the battery cluster can reach a fully charged state as soon as possible to meet the SOC calibration conditions of the battery cluster.

[0159] Optionally, the execution entity of step S712 can also be SACU.

[0160] S713, the battery clusters that require calibration under EMS control are in standby mode and do not participate in energy storage scheduling control.

[0161] It should be understood that when the BMS determines that the SOC of a battery cluster requiring correction is greater than the first threshold, achieving full charge is easier than full discharge for that cluster. Therefore, the cluster needs to be charged to reach full charge. Consequently, when the EMS determines that the energy storage system is not charging, the cluster requiring correction should be put into standby mode and not participate in energy storage scheduling control. This prevents the SOC of the cluster from decreasing, which would hinder reaching full charge.

[0162] Alternatively, the battery cluster to be calibrated can be put into standby mode by putting the DC inverter connected to the battery cluster into standby mode.

[0163] Alternatively, if the calibration speed is not a priority, the battery cluster that needs calibration can continue to operate in the same power distribution mode as other battery clusters during charging / discharging until the SOC calibration condition is met.

[0164] Optionally, the execution entity of step S713 can also be SACU.

[0165] S714, EMS controls the battery clusters that need correction to participate in charging within the constraints of the BMS until the SOC correction condition is reached.

[0166] It should be understood that when the BMS determines that the SOC of a battery cluster requiring correction is greater than the first threshold, achieving full charge is easier than full discharge for that cluster. Therefore, the cluster needs to be charged to reach full charge. Thus, when the EMS determines that the energy storage system is charging, it should ensure that the cluster requiring correction participates in charging. Furthermore, by controlling the charging of this cluster within the constraints of the BMS—that is, charging at the maximum charging rate allowed by the BMS (correction mode)—it is beneficial for the cluster to reach full charge as quickly as possible, thereby meeting the SOC correction conditions.

[0167] It should also be understood that the calibration mode refers to the discharge power P = P1max of the DC converter connected to the battery cluster to be calibrated controlled by the EMS, where P1max is the maximum discharge power that can be operated under the constraints of the current limiting table or power limiting table of the battery cluster to be calibrated provided by the BMS, until the battery cluster to be calibrated meets the SOC calibration conditions.

[0168] Alternatively, if calibration speed is not a priority, the battery cluster requiring calibration can continue to operate under the same power distribution mode (normal mode) as other battery clusters during charging / discharging until the SOC calibration condition is reached. The normal mode is as described in S709 and will not be repeated here.

[0169] It should be understood that for n PCS, the power can be evenly distributed among the PCS according to P*, that is, the power allocated to each PCS is P* / n.

[0170] Optionally, the execution entity of step S709 can also be SACU.

[0171] It should be understood that using the battery cluster voltage or whether the SOC has reached a fully charged / fully discharged state as the standard for judging whether the battery cluster has met the SOC correction conditions, or using other common standards that can be easily conceived by those skilled in the art, are all within the scope of protection of this application.

[0172] Through the above control strategy, independent decoupled management of each battery cluster can be achieved, minimizing the impact of SOC correction on the energy storage system; furthermore, by performing online SOC correction on each battery cluster in turn according to the control strategy of this invention, the overall SOC accuracy of the energy storage system can be improved; finally, through the above strategy, an independent battery cluster correction operation mode can be provided, enabling rapid correction of battery cluster SOC.

[0173] for Figure 3 The architecture shown in this application, the SOC online correction control strategy and the... Figure 2 The online correction control strategy for SOC shown is similar to that of... Figure 2 The difference between the online correction control strategy for SOC shown is that, in order to Figure 3 In the architecture shown, the power allocation in steps S708-S709 and S713-S714 is for the power allocation of the PCS, and the DC converter can operate in voltage source mode.

[0174] for Figure 4 The architecture shown in this application, the SOC online correction control strategy and the... Figure 2 The online correction control strategy for SOC shown is similar to that of... Figure 2 The difference between the online correction control strategy for SOC shown is that, in order to Figure 4 In the architecture shown, the power allocation in steps S708-S709 and S713-S714 is for the power allocation of PCS. By controlling the power of each PCS, the charging / discharging power of each battery cluster can be controlled.

[0175] for Figure 5 The architecture shown in this application, the SOC online correction control strategy and the... Figure 2 The online correction control strategy for SOC shown is similar to that of... Figure 2 The difference between the online correction control strategy for SOC shown is that, in order to Figure 5 In one of the architectures shown, the PCS in steps S709 and S714 can directly accept P* control.

[0176] It should be understood that the above content details a control method for an energy storage system provided by this application. The execution subject of this method is the controller in the energy storage system. For example, the controller can be an EMS or an SACU, and this application does not limit it.

[0177] It should be understood that the components in the energy storage system of this application embodiment can be used to perform... Figure 6 and Figure 7 The control method of the energy storage system shown, and its corresponding beneficial effects and functions, can be found in the detailed description of the control method of the energy storage system above, and will not be repeated here.

[0178] As used in this specification, the terms "component," "module," "system," etc., are used to refer to computer-related entities, hardware, firmware, combinations of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or a computer. As illustrated, applications running on computing devices and computing devices can both be components. One or more components may reside in a process and / or an execution thread, and components may be located on a single computer and / or distributed among two or more computers. Furthermore, these components can be executed from various computer-readable media on which various data structures are stored. Components can communicate, for example, via local and / or remote processes based on signals having one or more data packets (e.g., data from two components interacting with another component between a local system, a distributed system, and / or a network, such as the Internet interacting with other systems via signals).

[0179] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0180] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0181] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0182] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0183] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0184] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0185] It should also be noted that the terms "first," "second," and "third" used in the embodiments of this application are for ease of description and should not be construed as limiting the scope of application of the embodiments of this application.

[0186] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for an energy storage system, characterized in that, The energy storage system includes multiple energy storage unit clusters, multiple DC converters, and a controller. Each energy storage unit cluster corresponds one-to-one with one of the multiple DC converters, allowing the controller to individually control each of the multiple energy storage unit clusters. The method is executed by the controller and includes: It is determined that the first energy storage unit cluster among the plurality of energy storage unit clusters needs to be calibrated; Based on the State of Charge (SOC) of the first energy storage unit cluster and the current charging or discharging state of the energy storage system, the first energy storage unit cluster is controlled to charge, discharge, or standby mode to achieve the SOC correction condition, wherein the SOC correction condition is a fully charged or fully discharged state. The control method further includes: If the State of Charge (SOC) of the first energy storage unit cluster is greater than or equal to a first threshold, when the energy storage system is in a charging state, the first energy storage unit cluster is controlled to charge at a power greater than that of the energy storage system in normal operating mode. The charging power in normal operating mode refers to the charging power allocated by the energy storage system based on the SOC of the multiple energy storage unit clusters. When the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a charging state; or... If the SOC of the first energy storage unit cluster is less than a first threshold, when the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to discharge at a discharge power greater than that of the energy storage system in normal operating mode. The discharge power in normal operating mode refers to the discharge power of the energy storage system when allocating power according to the SOC of the multiple energy storage unit clusters. When the energy storage system is in a charging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a discharging state.

2. The method according to claim 1, characterized in that, The step of controlling the first energy storage unit cluster to charge includes: The first energy storage unit cluster is controlled to charge at the maximum charging power of the energy storage system, which is greater than the charging power in the normal operating mode and is the maximum power calculated by the battery management system (BMS); or... The control of the first energy storage unit cluster to discharge includes: The first energy storage unit cluster is controlled to discharge at the maximum discharge power of the energy storage system, which is greater than the discharge power in the normal operating mode and is the maximum power calculated by the battery management system (BMS).

3. The method according to claim 1 or 2, characterized in that, The step of determining that the first energy storage unit cluster among the plurality of energy storage unit clusters needs to be calibrated includes: Receive the cumulative running time Tr of the first energy storage unit cluster since the last SOC correction time point and the cumulative non-running time Td of the first energy storage unit cluster since the last SOC correction time point sent by the BMS of the energy storage system; Based on Tr and Td, it is determined that the first energy storage unit cluster needs to be calibrated.

4. The method according to claim 3, characterized in that, The step of determining that the first energy storage unit cluster needs correction based on Tr and Td includes: If Tr is greater than or equal to the cumulative operating time Ts that needs correction, then the first energy storage unit cluster is determined to be the energy storage unit cluster that needs correction; or, If Td is greater than or equal to the cumulative non-operation time Tp that requires correction, then the energy storage unit cluster is determined to be an energy storage unit cluster that requires correction.

5. The method according to claim 4, characterized in that, When multiple energy storage unit clusters are energy storage unit clusters that need to be calibrated, the first energy storage unit cluster is determined to need calibration according to its priority order.

6. The method according to claim 1, characterized in that, The method further includes: When the first energy storage unit cluster reaches the SOC correction condition, the BMS of the energy storage system is notified to perform SOC correction on the first energy storage unit cluster.

7. The method according to claim 1, characterized in that, The method further includes: Receive a notification from the BMS of the energy storage system that the SOC calibration of the first energy storage unit cluster is complete; The first energy storage unit cluster is controlled to charge, discharge, or standby in the normal operating mode of the energy storage system. The normal operating mode refers to the mode in which the energy storage system allocates power according to the SOC of the multiple energy storage unit clusters.

8. An energy storage system, characterized in that, The energy storage system includes multiple energy storage unit clusters, multiple DC converters, a controller, and a battery management system (BMS). The multiple energy storage unit clusters correspond one-to-one with the multiple DC converters so that the controller can individually control each of the multiple energy storage unit clusters. The BMS is used to obtain the State of Charge (SOC) of the plurality of energy storage unit clusters and send the SOC of the plurality of energy storage unit clusters to the controller; The controller is used to determine that the first energy storage unit cluster among the plurality of energy storage unit clusters needs calibration, and, based on the SOC of the first energy storage unit cluster and the current charging or discharging state of the energy storage system, controls the first energy storage unit cluster to charge, discharge, or standby, so that the first energy storage unit cluster reaches the SOC calibration condition, wherein the SOC calibration condition is a fully charged state or a fully discharged state. The controller is used to: If the State of Charge (SOC) of the first energy storage unit cluster is greater than or equal to a first threshold, when the energy storage system is in a charging state, the first energy storage unit cluster is controlled to charge at a power greater than that of the energy storage system in normal operating mode. The charging power in normal operating mode refers to the charging power allocated by the energy storage system based on the SOC of the multiple energy storage unit clusters. When the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a charging state; or... If the SOC of the first energy storage unit cluster is less than a first threshold, when the energy storage system is in a discharging state, the first energy storage unit cluster is controlled to discharge at a discharge power greater than that of the energy storage system in normal operating mode. The discharge power in normal operating mode refers to the discharge power of the energy storage system when allocating power according to the SOC of the multiple energy storage unit clusters. When the energy storage system is in a charging state, the first energy storage unit cluster is controlled to standby until the energy storage system is in a discharging state.

9. The energy storage system according to claim 8, characterized in that, The controller is used for: The first energy storage unit cluster is controlled to charge at the maximum charging power of the energy storage system, which is greater than the charging power in the normal operating mode and is the maximum power calculated by the BMS. or, The first energy storage unit cluster is controlled to discharge at the maximum discharge power of the energy storage system, which is greater than the discharge power in the normal operation mode and is the maximum power calculated by the BMS.

10. The energy storage system according to claim 8 or 9, characterized in that, The BMS is also used to send the controller the cumulative running time Tr of the first energy storage unit cluster since the last SOC correction time and the cumulative non-running time Td of the first energy storage unit cluster since the last SOC correction time. The controller is used to determine, based on Tr and Td, that the first energy storage unit cluster needs to be calibrated.

11. The energy storage system according to claim 10, characterized in that, The controller is used for: If Tr is greater than or equal to the cumulative operating time Ts that needs correction, then the first energy storage unit cluster is determined to be the energy storage unit cluster that needs correction; or, If Td is greater than or equal to the cumulative non-operation time Tp that requires correction, then the energy storage unit cluster is determined to be an energy storage unit cluster that requires correction.

12. The energy storage system according to claim 11, characterized in that, The controller is used to determine, according to priority order, that the first energy storage unit cluster needs to be calibrated when multiple energy storage unit clusters are energy storage unit clusters that need to be calibrated.

13. The energy storage system according to claim 8, characterized in that, The controller is further configured to notify the BMS to perform SOC correction on the first energy storage unit cluster when the first energy storage unit cluster reaches the SOC correction condition.

14. The energy storage system according to claim 8, characterized in that, The BMS is also used to send a notification to the controller that the SOC calibration of the first energy storage unit cluster is complete; The controller is also configured to receive a notification from the BMS that the SOC correction of the first energy storage unit cluster is complete, and control the first energy storage unit cluster to charge, discharge, or standby in the normal operating mode of the energy storage system. The normal operating mode refers to the mode in which the energy storage system allocates power according to the SOC of the multiple energy storage unit clusters.

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