Performance control method of energy storage system and energy storage system

Abstract

The invention discloses a performance control method of an energy storage system and a corresponding energy storage system, and the method comprises the steps: collecting the real-time data of a plurality of battery modules in the energy storage system, and carrying out the different processing and judgment of the data; according to the processing and judgment results, consistency equalization charging and discharging operation or non-stop battery module replacement operation is executed, so that SOC equalization of battery modules of different specifications in the energy storage system is achieved, the wooden barrel effect in the energy storage system is effectively solved, or non-stop battery module replacement of the energy storage system is achieved, and the energy storage efficiency is improved. And the continuous operation efficiency and the safe and stable operation time in the energy storage system are improved.

Description

Technical Field

[0001] The present invention relates to the field of energy storage control, and in particular to a performance control method based on an energy storage system and an energy storage system for executing the performance control method. Background Art

[0002] In the cascade energy storage system, since retired battery modules are used, compared with new battery modules, the battery performance of retired battery modules is significantly different from that of new battery modules in terms of capacity, charge and discharge rate, battery internal resistance, consistency, etc.

[0003] The new battery module energy storage system has good consistency, SOC, and capacity of its battery modules are almost the same. Therefore, during the charging and discharging process, the energy storage system can ensure that the SOC of all battery modules remains consistent within a charging and discharging cycle, and they are fully charged or discharged at the same time.

[0004] However, in the cascade energy storage system, the remaining capacity and SOC of each retired battery module are different. During the system discharge process, the battery module with the smallest initial SOC or the smallest capacity will be discharged first; during the system charging process, the battery module with the smallest initial SOC or the smallest capacity will be fully charged first. As a result, other battery modules with large capacity are not fully charged or discharged. This is the "barrel effect" of the cascade energy storage system, and the battery module utilization rate is not maximized.

[0005] At the same time, since the degree of attenuation of each battery module in the cascade energy storage system is different, the time it takes to reach the point where it does not meet the requirements of the energy storage system is also different, so the battery needs to be replaced frequently. However, the current energy storage system battery replacement is carried out under shutdown, which takes about 4 hours each time, including the shutdown preparation time, shutdown time, and normal operation time of the system after shutdown. If the battery is replaced frequently, the system will not run continuously and will not play its maximum role; secondly, frequent shutdown and startup will also damage the system itself, causing system instability and easily causing failures.

[0006] How to reduce the adverse effects of the barrel effect and battery replacement in the above-mentioned cascade energy storage system has become a technical problem that needs to be urgently solved by technicians in this field. Summary of the invention

[0007] The present invention provides a discharge and charging method and an energy storage system based on battery module SOC consistency balance, which are used to solve the technical problem of low utilization rate of battery modules in existing cascade energy storage systems.

[0008] In order to solve the above technical problems, the technical solution proposed by the present invention is: A performance control method for an energy storage system, the energy storage system comprising a plurality of battery modules, the performance control method for the energy storage system comprising the following steps: Periodically reading real-time parameters of the plurality of battery modules through a control system, wherein the real-time parameters include a real-time SOC value and a real-time SOH value; When the read parameter is the real-time SOC value, a consistent balanced discharge operation is performed: Sort multiple battery modules in ascending order according to the real-time SOC values, and select the N battery modules with the lowest ranking as the target module 1; connect the target module 1 to the energy storage system to participate in the discharge, and bypass other battery modules; when the target module 1 is connected to the energy storage system, the real-time output voltage Vin of the energy storage system is within the preset stable voltage Vstable interval; or When the read parameter is the real-time SOC value, the consistent equalization charging operation is performed: Sort multiple battery modules in ascending order according to the real-time SOC values, and select the top N battery modules as target modules 2; connect the target modules 2 to the energy storage system for charging, and bypass other battery modules; When the parameter read is the real-time SOH value, the battery module replacement operation is performed without stopping the machine: The real-time SOH values ​​of multiple battery modules are judged, and a battery module with a real-time SOH value less than 60.0% is selected as the target module 3; the target module 3 is bypassed, and other battery modules except the target module 3 are connected to the energy storage system to participate in charging or discharging, and then the data communication between the target module 3 and the control system is disconnected, and the target module is replaced; after the replacement is completed, the data communication between the replaced target module 3 and the control system is reconnected, and then the target module 3 group is reconnected to the energy storage system to participate in charging or discharging.

[0009] As a further optimization of the above technical solution, when a consistent balanced discharge operation is performed, the following conditions are met: the total stable output voltage of the energy storage system is within the voltage range of the energy storage transformer; when a consistent balanced charging operation is performed, the following conditions are met: the total input voltage of the energy storage system is within the voltage range of the energy storage transformer; when a battery module replacement operation is performed without stopping the system, the following conditions are met: the total stable output voltage and the total input voltage of the energy storage system are within the voltage range of the energy storage transformer.

[0010] As a further preferred embodiment of the above technical solution, periodically reading the real-time SOC values ​​of multiple battery modules specifically refers to scanning the real-time SOC values ​​of multiple battery modules that are connected to the energy storage system and participating in discharge or charging; periodically reading the real-time SOH values ​​of multiple battery modules specifically refers to scanning the real-time SOH values ​​of multiple battery modules that participate in discharge or charging after each charging or discharging of the energy storage system.

[0011] As a further optimization of the above technical solution, when performing the operation of replacing the battery module without stopping the machine, the battery data and real-time SOC values ​​of multiple battery modules are synchronously read, and the battery data is preprocessed and initialized to obtain the cycle parameters; when charging or discharging other battery modules except the target module 3, execute: S1. Calculate the current total capacity of the battery according to the battery data, and calculate the aging coefficient of the battery, and calculate the time of the current charge and discharge cycle of the battery based on the aging coefficient and cycle parameters combined with Gaussian regression and extended Kalman filtering; S2. The time of the current battery charge and discharge cycle is used as the time of the next battery charge and discharge cycle and the battery health status is calculated in combination with the aging coefficient. The battery balancing time is calculated according to the battery health status and a preset cutoff coefficient. The charge and discharge time of the battery in the next charge and discharge process is adjusted based on the balancing time to complete the energy balancing of the battery in the charge and discharge process.

[0012] As a further preferred embodiment of the above technical solution, in S1, the battery data includes voltage, current, capacity change and battery calibrated capacity; the cycle parameters include real-time battery voltage collected at several fixed intervals, and the cycle parameters are obtained based on the voltage in the battery data; the preprocessing operations performed on the battery data include missing value processing, data deduplication, outlier processing and data segment cutting and reconstruction.

[0013] As a further optimization of the above technical solution, in S1, the current total capacity of the battery is calculated according to the battery data and the battery aging coefficient is further calculated in combination with the battery health formula, including: obtaining the battery charge change during battery charging and discharging based on the current, calculating the current total capacity of the battery in combination with the capacity change, and calculating the battery aging coefficient based on the current total capacity and the battery calibrated capacity.

[0014] As a further preferred embodiment of the above technical solution, in S1, the aging coefficient is calculated by the following formula: ; in, is the rated capacity of the battery; Indicates the current total capacity, calculated using the following formula: ; In the formula, and Indicates different moments in the charging or discharging process, For the corresponding The remaining battery capacity; For the corresponding The remaining battery capacity; for The battery current at that moment.

[0015] As a further optimization of the above technical solution, in S1, the calculation of the time of the current battery charge and discharge cycle based on the cycle parameters and the aging coefficient combined with Gaussian regression and extended Kalman filtering includes: performing Gaussian regression on the cycle parameters, and then using the cycle parameters after Gaussian regression as the cycle parameters of the next charge and discharge cycle to perform extended Kalman filtering to calculate the time of the current battery charge and discharge cycle; the Gaussian regression uses a linear function As the mean function, the squared exponential covariance function was chosen as the kernel function.

[0016] As a further preferred embodiment of the above technical solution, in S2, the balancing time includes a charging balancing time and a discharging balancing time, and the cut-off coefficient includes a charging cut-off coefficient and a discharging cut-off coefficient; The charge equalization time is calculated by the following formula: ; in, Indicates the charge equalization time; Indicates the amount of power transferred during battery balancing; Said Calculated by the following formula: ; in, represents the charge cut-off coefficient, express Moment Save the remaining battery power. Indicates the average remaining chargeable capacity of the battery; For the Battery health status at each cycle; Said Calculated by the following formula: ; Where N is the number of cycles; The discharge balance time is calculated by the following formula: ; in Indicates the amount of electricity transferred by battery discharge; Said Calculated by the following formula: ; in, represents the discharge cut-off coefficient; Indicates the average discharge capacity of the battery at the end of discharge; Said Calculated by the following formula: ; Where N is the number of cycles; Said Calculated by the following formula: ; in, Time to fully charge the battery; is a given charge and discharge current.

[0017] Based on the same technical concept, the present invention also provides an energy storage system for executing the above-mentioned performance control method, comprising: an EMS controller, a plurality of battery cells arranged in series; each battery cell comprises a battery module, a control module and a battery management unit, the battery module is connected to the energy storage system through the control module, the battery management unit is used to collect the real-time SOC value, real-time SOH value and battery data of the corresponding battery module, and the EMS controller establishes communication with the control module and the battery management unit respectively; The battery management unit is used to periodically collect the real-time SOC value and real-time SOH value of the battery module and send them to the EMS controller; The EMS controller is used to sort the real-time SOC values ​​of multiple battery modules according to the numerical values ​​when in the discharge state, select the top N battery modules with large real-time SOC values ​​as the target module 1; and control the corresponding control module to connect the target module 1 to the energy storage system to participate in the discharge, and bypass other battery modules; and / or The EMS controller is used to sort the real-time SOC values ​​of multiple battery modules according to the numerical values ​​when in the charging state, select the top N battery modules with small real-time SOC values ​​as the target module 2; and control the corresponding control module to connect the target module 2 to the energy storage system for charging, and bypass other battery modules; and / or The EMS controller is used to judge the real-time SOH values ​​of multiple battery modules when in a charging state or a discharging state, select a battery module with a real-time SOH value less than 60.0% as the target module 3; and control the corresponding control module to bypass the target module 3, and then control the corresponding battery management unit to disconnect data communication; and / or The EMS controller is used to control the battery management unit corresponding to the replaced target module to re-establish data communication when in a charging state or a discharging state, and control the corresponding control module to re-connect the replaced target module 3 to the energy storage system to participate in charging or discharging.

[0018] As a further preferred embodiment of the above technical solution, the EMS controller is used to calculate the battery health status of multiple battery modules and obtain the balancing time when in a charging state or a discharging state, and control the corresponding control module to adjust the charging and discharging time of the battery module during the next charging and discharging process.

[0019] As a further preferred embodiment of the above technical solution, the control module includes a K1 high-frequency switch and a K2 high-frequency switch, the positive electrode of the battery module is connected to the emitter of the K1 high-frequency switch, the collector of the K1 high-frequency switch is connected to the emitter of the K2 high-frequency switch, and the collector of the K2 high-frequency switch is connected to the negative electrode of the battery module.

[0020] As a further preferred embodiment of the above technical solution, the output voltages of the battery modules are all equal.

[0021] As a further preferred embodiment of the above technical solution, the energy storage system is a cascade energy storage system, and the battery module is a retired lithium battery module. The present invention has the following beneficial effects: In the present invention, by collecting the real-time SOC values ​​and real-time SOH values ​​of multiple battery modules in the energy storage system, on the one hand, the target module 1 with a high SOC value and the target module 2 with a low SOC value can be screened out for discharge and charging operations respectively, and then the above steps can be repeated to achieve battery balancing of different specifications in the energy storage system, effectively solving the "barrel effect" in the energy storage system and maximizing the utilization of the battery modules; on the other hand, by comparing the SOH value of each battery module with the standard value (60%) in the energy storage system composed of multiple battery modules, first determine which batteries need to be replaced, and then replace the battery modules without stopping the energy storage system according to the bypass control of the battery modules, thereby improving the continuous operation efficiency and safe and stable operation time in the energy storage system.

[0022] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 A topological diagram of the energy storage system provided by the present invention; Figure 2 A diagram showing the state change of the K1 high-frequency switch being turned on / off under two hypothetical conditions of the energy storage system discharging provided in Example 1; Figure 3A diagram showing the state change of the K1 high-frequency switch being turned on / off under two hypothetical conditions of charging the energy storage system provided in Example 1; Figure 4 A flowchart of performing a balanced consistent charging and discharging operation in the performance control method of the energy storage system of Example 1; Figure 5 A flowchart of performing a balanced consistent charging and discharging operation in a performance control method for an energy storage system according to Embodiment 3; Figure 6 This is a flow chart of performing a battery capacity balancing operation in the performance control method of the energy storage system of Example 5. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0025] Embodiment 1: A performance control method for an energy storage system of the present invention is used to achieve SOC consistency balance of battery modules in the energy storage system and solve the technical problem of low utilization rate of battery modules in the energy storage system.

[0026] To solve the above technical problems, it is necessary to define: Remaining capacity of retired lithium battery (Ah): the remaining capacity of retired lithium battery module after attenuation, calculated once at the end of the system charging (or discharging) cycle; Real-time capacity of retired lithium battery (Ah): the real-time capacity of retired lithium battery module; Retired lithium battery SOC (%): retired lithium battery real-time capacity / retired lithium battery remaining capacity*100%; SOC n : SOC of n# lithium battery module; Lithium battery module bypass: In an energy storage system composed of multiple lithium batteries, the lithium battery module that is not connected to the system because the access switch is disconnected is called bypass; Lithium battery module access: In an energy storage system composed of multiple lithium batteries, the lithium battery module is connected to the system because the access switch is turned on. Switch reversal: two high-frequency switches in the control panel, that is, K1 high-frequency switch is disconnected, K2 high-frequency switch must be closed, K1 high-frequency switch is closed, K2 high-frequency switch must be disconnected; Among them, this embodiment adopts the method of energy storage system performance control of embodiment 6, that is, the energy storage system includes multiple battery units, EMS controller (including operation platform) and PCS, each battery unit is composed of 1 control board, 1 group of lithium battery modules and 1 BMS, each control board has two high-frequency switches (K1 and K2) to control the bypass and access of lithium battery modules. All lithium battery modules are connected in series due to the disconnection of the high-frequency switch K1 of the control board and the conduction of the high-frequency switch K2. The total voltage output after the series connection is V 输 ; BMS collects the voltage, temperature, current, SOC and other parameters of each lithium battery module, and obtains the real-time capacity, SOC, SOH and other data of the lithium battery module through logical operations, and exchanges data with the EMS controller through communication; The EMS controller mainly performs the system's logical operation algorithm control to achieve stable and safe operation of the energy storage system, intuitively display important data, receive manual operation instructions, and exchange data with the BMS, control board, and PCS; The PCS mainly realizes the AC / DC inverter function of electric energy.

[0027] The energy storage system meets the following conditions: Condition 1: Assuming the number of lithium battery cells is m, the voltage of each lithium battery module is 3.2*m (V); Condition 2: The entire control system can be composed of n units, that is, there are n lithium battery modules, and the maximum total voltage of the system is 3.2*m*n (V); Condition 3: Assume that the system outputs a stable DC voltage of 3.2*m*(n-10)V≤V 输 ≤3.2*m*(n-9)V; Condition 4: The SOC data of each lithium battery module obtained by the EMS controller through communication with the BMS are SOC 1 , SOC 2 , SOC 3 ┈┈SOC n ; Condition 5: K1 and K2 in the control board are high-frequency semiconductor switches, which are in an opposing relationship with each other, that is, when the K1 high-frequency switch is disconnected, the K2 high-frequency switch must be closed, and when the K1 high-frequency switch is closed, the K2 high-frequency switch must be disconnected; Condition 6: The time it takes for the EMS controller to scan a unit is t (ms), that is, the time it takes for the K1 high-frequency switch or the K2 high-frequency switch to be turned on or off in the system is t (ms), and the scanning time of each unit is equal to t (ms); Condition 7: The system outputs a stable DC voltage of 3.2*m*(n-10)V≤V 输 ≤3.2*m*(n-9)V, we get: In each scanning cycle T, at least n-10 lithium battery modules are connected to the system; Condition 8: Based on conditions 6 and 7, we can get: the total time for the EMS controller to scan the entire system in one scanning cycle is T = (n-10) * t (ms); Condition 9: From conditions 3 and 7, we can get: in one scanning cycle, 10 modules do not participate in the operation, that is, the K1 high-frequency switch in the 10 unit control boards is disconnected and the K2 high-frequency switch is closed, which we call lithium battery module bypass, and the remaining lithium battery modules have the K1 high-frequency switch closed and the K2 high-frequency switch disconnected, which is called lithium battery module access; Condition 10: Define the upper limit of SOC when charging the lithium battery module as 100%, and the lower limit of SOC when discharging as 10%.

[0028] Energy storage systems based on the above structure, such as Figure 4 As shown, the control method of this embodiment is as follows: A. When the system is in the discharge state, perform the following steps: Step A1: The EMS controller obtains the SOC data of each lithium battery module based on the communication BMS data, that is, SOC 1 , SOC 2 , SOC 3 ┈┈SOC n ; Step A2: The EMS controller performs sorting based on the real-time SOC data of each lithium battery module; Assumptions: SOC 1 <SOC 2 <SOC 3 <┈┈<SOC n-1 <SOC n ; Step A3: When the system is in the discharge state, within the first discharge scanning cycle T, the EMS controller makes a decision that the 1# to 10# lithium battery modules are bypassed by the system and do not discharge, and then sends a command to the control board to disconnect the K1 high-frequency switch from the 1# to 10# lithium battery modules and close the K2 high-frequency switch; Step A4: After the first discharge scan cycle T is completed, the EMS controller again compares the SOC real-time data of the lithium battery module. ①If still: SOC 1 <SOC 2 <SOC 3 <┈┈<SOC n-1 <SOC n , then in the second discharge scanning cycle T, the EMS controller still makes the decision that the 1# to 10# lithium battery modules are bypassed by the system and do not discharge, and then sends instructions to the control board to continue to disconnect the K1 high-frequency switch from the 1# to 10# lithium battery modules and continue to close the K2 high-frequency switch; ②If yes: SOC 1 <SOC 2 <┈┈SOC 9 <SOC 11 <SOC 10 <SOC 12 <┈┈SOC n-1 <SOC n , then in the second scanning discharge cycle T, the EMS controller makes the decision that the 1# to 9# and 11# lithium battery modules are bypassed by the system and do not discharge, and then sends instructions to the control board, the K1 high-frequency switch of the 1# to 9# lithium battery modules continues to be disconnected, and the K2 high-frequency switch continues to be closed, but 10# and 11# perform the opposite operation, the K1 high-frequency switch of the 10# lithium battery module changes from disconnected to closed, and the K2 high-frequency switch changes from closed to disconnected; the K1 high-frequency switch of the 11# lithium battery module changes from closed to disconnected, and the K2 high-frequency switch changes from disconnected to closed; ③ By analogy, after the second discharge scan cycle, the EMS controller continues to compare the real-time SOC data of the lithium battery module, and determines which lithium battery modules are bypassed and connected based on the comparison results, and then issues instructions to perform related actions. The conduction status of the bypass and access switches is as follows: Figure 2 shown.

[0029] According to the above principle, after the system has gone through multiple scanning discharge cycles T, the SOC of all lithium battery modules will gradually tend to the same level, forming a consistent and balanced control of SOC, until the SOC of all lithium battery modules reaches 10% and the system stops discharging.

[0030] B. When the system is in charging state, perform the following steps: Step B1: When the system is in the charging state, within the first charging scan cycle T, the EMS controller makes a decision that the (n-9)# to n# lithium battery module groups are bypassed by the system and are not charged, thereby sending instructions to the control board to disconnect the K1 high-frequency switch from the (n-9)# to n# lithium battery modules and close the K2 high-frequency switch.

[0031] Step B2: After the first charging scan cycle T is completed, the EMS controller again compares the obtained real-time SOC data of the lithium battery module. ①If still: SOC 1 <SOC 2 <SOC 3 <┈┈<SOC n-1 <SOC n, then in the second charging scan cycle T, the EMS controller still makes the decision that the (n-9)# to n# lithium battery module group is bypassed by the system and does not charge, and then sends instructions to the control board to continue to disconnect the K1 high-frequency switch from the (n-9)# to n# lithium battery module and continue to close the K2 high-frequency switch; ②If yes: SOC 1 <SOC 2 <┈┈SOC n-11 <SOC n-9 <SOC n-10 <SOC n-8 <┈┈SOC n-1 <SOC n , then in the second charging scan cycle T, the EMS controller makes the decision that the n# to (n-8)# and (n-10)# lithium battery modules are bypassed by the system and are not charged, and then sends instructions to the control board. The K1 high-frequency switch of the n# to (n-8)# lithium battery modules continues to be disconnected, and the K2 high-frequency switch continues to be closed. However, the (n-9)# and (n-10)# perform the opposite operation. The K1 high-frequency switch of the (n-9)# lithium battery module changes from disconnected to closed, and the K2 high-frequency switch changes from closed to disconnected; the K1 high-frequency switch of the (n-10)# lithium battery module changes from closed to disconnected, and the K2 high-frequency switch changes from disconnected to closed; ③ By analogy, after the second charging scan cycle, the EMS controller continues to compare the real-time SOC data of the lithium battery module, and determines which lithium battery modules are bypassed and connected based on the comparison results, and then issues instructions to perform related actions. The conduction status of the bypass and access switches is as follows: Figure 3 shown.

[0032] According to the above principle, after the system has gone through multiple charging scan cycles T, the SOC of all lithium battery modules will gradually tend to the same level, forming a consistent and balanced control of SOC, until the SOC of all lithium battery modules reaches 100% and the system stops charging.

[0033] Embodiment 2: Embodiment 2 is an extended embodiment of Embodiment 1. The performance control method of the energy storage system of this embodiment is used to achieve SOC consistency balance of battery modules in the energy storage system and solve the technical problem of low utilization rate of battery modules in the energy storage system.

[0034] Among them, this embodiment adopts the method of energy storage system performance control of embodiment 6, that is, the energy storage system of this embodiment includes 30 battery cells, EMS controller and PCS, each battery cell includes 1 group of lithium battery modules (a total of 30 lithium battery modules, each lithium battery module is 1P16S, the single cell voltage is 3.2V, and the voltage of each module is 51.2V, and the total system voltage is 1536V), and a corresponding control board and 1 BMS, each control board has two high-frequency switches K1 and K2 to control the bypass and access of the lithium battery module. All lithium battery modules are connected in series due to the disconnection of the high-frequency switch K1 of the control board and the conduction of the high-frequency switch K2.

[0035] The energy storage system meets the following conditions: Condition 1: Assuming the system output voltage is 768V, the number of lithium battery modules connected to the system in one scan cycle is 15; Condition 2: Assuming that the scanning period of a single module is t=100ms, the scanning period of the system is T=1500ms; Condition 3: Assume that the specific SOC data of 30 lithium battery modules obtained by the EMS controller from the BMS unit are shown in Table 1 below:

[0036] Condition 4: From condition 3, we can get: SOC 1 <SOC 2 <SOC 3 <┈┈<SOC 29 <SOC 30 , A. When the system is in discharge state: When the system is in the discharge state, within the first discharge scan cycle T=1500ms, based on conditions 1 and 4, the EMS controller makes a decision that the 1# to 15# lithium battery modules are bypassed by the system and do not discharge, and then sends a command to the control board to disconnect the K1 high-frequency switch from the 1# to 15# lithium battery modules and close the K2 high-frequency switch.

[0037] After the first discharge scan cycle T=1500ms is completed, the EMS controller again compares the obtained real-time SOC data of the lithium battery module; assuming that the obtained data is as shown in Table 2 below:

[0038] From the above data, we can get: after the first scanning cycle, there are: Condition 5: SOC 1 <SOC 2 <SOC 3 <┈┈<SOC 29 <SOC 30 , In the second discharge scanning cycle T=1500ms, based on conditions 1 and 5, the EMS controller makes the decision that the 1# to 15# lithium battery modules continue to be bypassed by the system and do not discharge, and then sends instructions to the control board to continue to disconnect the K1 high-frequency switch from the 1# to 15# lithium battery modules and close the K2 high-frequency switch.

[0039] After n discharge scan cycles T have passed, but after a scan cycle T has ended; assuming that the real-time SOC data of the lithium battery module obtained by the EMS controller is as shown in Table 3 below:

[0040] From the above table, we can get condition 6: SOC 1 <SOC 2 <┈┈<SOC 14 <SOC 16 <SOC 15 <┈┈<SOC 29 <SOC 30 , Then, in the n+1th discharge scanning cycle T=1500ms, according to conditions 1 and 6, the EMS controller makes a decision that the 1# to 14# lithium battery modules continue to be bypassed by the system and do not discharge, while the 15# lithium battery module changes from bypass to access, and the 16# lithium battery module changes from access to bypass, and then sends instructions to the control board to continue to disconnect the K1 high-frequency switch from 1# to 14# lithium battery modules and close the K2 high-frequency switch. Close the K1 high-frequency switch of the 15# lithium battery module and disconnect the K2 high-frequency switch. Disconnect the K1 high-frequency switch of the 16# lithium battery module and close the K2 high-frequency switch.

[0041] According to the above situation, patrol until 30 modules are discharged to the same SOC, forming a lithium battery SOC consistency balance control method. When all lithium battery modules are discharged to SOC=10% by this SOC consistency balance control method, the discharge is stopped. At this time, all lithium battery modules fully realize full energy discharge in one discharge cycle.

[0042] B. When the system is in charging state: When the system is in the charging state, within the first charging scan cycle T=1500ms, based on conditions 1 and 4, the EMS controller makes a decision that the 16# to 30# lithium battery modules are bypassed by the system and are not charged, and then sends a command to the control board to disconnect the K1 high-frequency switch from the 16# to 30# lithium battery modules and close the K2 high-frequency switch.

[0043] After the first charging scan cycle T=1500ms is completed, the EMS controller again compares the obtained real-time SOC data of the lithium battery module. Assume that the obtained data is as shown in Table 4 below:

[0044] From the above data, we can get: after the first scanning cycle T ends, we have: Condition 7: SOC 1 <SOC 2 <SOC 3 <┈┈<SOC 29 <SOC 30 , Then, in the second charging scan cycle T=1500ms, based on conditions 1 and 7, the EMS controller makes the decision that the 16# to 30# lithium battery modules continue to be bypassed by the system and not charged, and then sends instructions to the control board to continue to disconnect the K1 high-frequency switch from the 1# to 15# lithium battery modules and close the K2 high-frequency switch.

[0045] After n charging scan cycles T have passed, but after a certain scan cycle T has ended; it is assumed that the real-time SOC data of the lithium battery module obtained by the EMS controller is as shown in Table 5 below:

[0046] From the above table, we get condition 8: SOC 1 <SOC 2 <┈┈<SOC 14 <SOC 16 <SOC 15 <┈┈<SOC 29 <SOC 30 , Then, in the n+1th charging scan cycle T=1500ms, according to conditions 1 and 8, the EMS controller makes a decision that the 17# to 30# lithium battery modules continue to be bypassed by the system and do not discharge, while the 16# lithium battery module changes from bypass to access, and the 15# lithium battery module changes from access to bypass, and then sends instructions to the control board to continue to disconnect the K1 high-frequency switch from the 17# to 30# lithium battery modules and close the K2 high-frequency switch. Close the K1 high-frequency switch of the 16# lithium battery module and disconnect the K2 high-frequency switch. Disconnect the K1 high-frequency switch of the 15# lithium battery module and close the K2 high-frequency switch.

[0047] According to the above situation, patrol until 30 modules are charged to the same SOC, forming a control method for SOC consistency balance of lithium battery modules. When all lithium battery modules are charged to SOC=100% by using this SOC consistency balance control method, charging is stopped. At this time, all lithium battery modules are fully charged in one charging cycle. Embodiment 3: A performance control method for an energy storage system of the present invention is used to realize replacement of battery modules of the energy storage system without stopping the system, thereby solving the technical problem of low continuous operation efficiency and safety of the energy storage system.

[0048] In order to solve the above technical problems, it is necessary to further define on the basis of Example 1: Nominal capacity of retired lithium batteries (Ah): the nominal capacity of retired batteries when they leave the factory; SOH of retired lithium battery (%): real-time capacity of retired lithium battery / nominal capacity of retired lithium battery*100%; SOH n : SOH of n# battery module; Among them, this embodiment adopts the method of energy storage system performance control of embodiment 6, that is, the energy storage system includes multiple battery units, EMS controller (including operation platform) and PCS, each battery unit is composed of 1 control board, 1 group of lithium battery modules and 1 BMS, each control board has two high-frequency switches (K1 and K2) to control the bypass and access of lithium battery modules. All lithium battery modules are connected in series due to the disconnection of the high-frequency switch K1 of the control board and the conduction of the high-frequency switch K2. The total voltage output after the series connection is V 输 ; BMS collects the voltage, temperature, current, SOC and other parameters of each lithium battery module, and obtains the real-time capacity, SOC, SOH and other data of the lithium battery module through logical operations, and exchanges data with the EMS controller through communication; The EMS controller mainly performs the system's logical operation algorithm control to achieve stable and safe operation of the energy storage system, intuitively display important data, receive manual operation instructions, and exchange data with the BMS, control board, and PCS; The PCS mainly realizes the AC / DC inverter function of electric energy.

[0049] The energy storage system meets the following conditions: Condition 1: Assuming the number of cells in a battery module is m, the voltage of each battery module is V=3.2*m (V); Condition 2: The entire energy storage system can be composed of n units, that is, there are n battery modules, and the maximum total voltage of the system is 3.2*m*n (V); Condition 3: Assume that the system outputs a stable DC voltage of 3.2*m*(n-10)V≤V DC输 ≤3.2*m*(n-9)V; Condition 4: The SOC data of each battery module obtained by the EMS controller through communication with the BMS are SOC 1 , SOC 2 , SOC 3 ┈┈SOC n ; Condition 5: The SOH data of each battery module obtained by the EMS controller through communication with the BMS are 1 , SOH 2 , SOH 3 ┈┈SOH n ; Condition 6: K1 and K2 in the control substrate are high-frequency semiconductor switches, which are in an opposing relationship with each other, that is, when the K1 high-frequency switch is disconnected, the K2 high-frequency switch must be closed, and when the K1 high-frequency switch is closed, the K2 high-frequency switch must be disconnected; Condition 7: The system outputs a stable DC voltage of 3.2*m*(n-10)V≤V 输 ≤3.2*m*(n-9)V, we get: In each charge and discharge cycle T, at most n-10 lithium battery modules are connected to the system, and at least 10 battery modules can be bypassed and not connected to the energy storage system; Condition 8: The SOH of all battery modules connected to the system must be greater than or equal to 60.0%; Condition 9: Define the upper limit of SOC when charging the battery module as 100.0% and the lower limit of SOC when discharging as 10.0%; Condition 10: The time for the EMS controller to scan a unit is t (ms), that is, the time for the K1 high-frequency switch or the K2 high-frequency switch to be turned on or off in the system is t (ms), and the scanning time of each unit is equal to t (ms); Condition 11: From conditions 7 and 10, we can get: the total time for one scanning cycle of the EMS controller to scan the entire system is T = (n-10) * t (ms).

[0050] Energy storage systems based on the above structure, such as Figure 5 As shown, the control method of this embodiment is as follows: Step S1: At the end of each charge (or discharge) of the energy storage system, the EMS controller obtains the remaining capacity and SOH value of each lithium battery module according to the communication BMS data; Step S2, judging the real-time SOH value of each battery module, selecting a lithium battery module with a real-time SOH value less than 60.0% as the target module; the EMS controller disconnects the K1 switch of the control board of the a lithium battery module and closes the K2 switch, bypassing the target module, but maintaining data communication between the BMS corresponding to the target module and the EMS controller; keeping other battery modules except the target module connected to the energy storage system to participate in charging or discharging; Step S3: During this or subsequent charging (or discharging) cycles, the EMS controller can only charge (na) battery modules according to their V DC输 To determine how many modules need to be bypassed, and then determine which modules are bypassed based on their SOH size; Step S4: In the subsequent charging (or discharging) cycle, if the EMS controller does not detect that the module with SOH < 60% is replaced or the module with SOH < 60% is added, the K1 switch of the control board of the module with SOH < 60% remains open and the K2 switch remains closed, but the data communication between the BMS and the EMS controller is maintained; Step S5: If ① the lithium battery module is not replaced, the battery modules participating in the charging (or discharging) operation of the energy storage system will become fewer and fewer. When V1+V2+V3+┅┅+Vn<V DC输 When the system stops, it stops running; If ② the operator finds that there is a module with SOH < 60% in the system from the system operation platform, he can select the battery on the operation platform and click the replacement button. After the EMS controller receives the replacement information from the operation platform, the K1 switch of the control panel of the corresponding a lithium battery module remains open and the K2 switch remains closed, which cannot be released and is in a locked state; and the data communication between the BMS and EMS controller of the a lithium battery module is disconnected, and the entire system is adjusted to the mode of (na) modules; the battery is replaced; when the battery replacement is completed, the operator Click on the work platform to confirm that the module has been replaced. After the EMS controller receives the confirmation information, it first restores the communication between the BMS and the EMS controller of the replaced a lithium battery module. When the detection data is correct, at the end of the next charging (or discharging) cycle, the EMS controller controls the K1 switch of the control board to close and the K2 switch to disconnect, and connects the replaced a battery module to the main circuit of the system and re-incorporates it into the scanning cycle, thereby starting a new round of charging and discharging cycle. The number of batteries is restored to n. At this point, the energy storage system completes the replacement of battery modules without stopping.

[0051] Embodiment 4: Embodiment 4 is an extended embodiment of Embodiment 3. The performance control method of the energy storage system of this embodiment is used to realize the replacement of battery modules of the energy storage system without stopping the energy storage system, thereby solving the technical problem of low continuous operation efficiency and safety of the energy storage system.

[0052] Among them, this embodiment adopts the method of energy storage system performance control of embodiment 6, that is, the energy storage system of this embodiment includes 30 battery cells, EMS controller and PCS, each battery cell includes 1 group of lithium battery modules (a total of 30 lithium battery modules, each lithium battery module is 1P16S, the single cell voltage is 3.2V, and the voltage of each module is 51.2V, and the total system voltage is 1536V), and a corresponding control board and 1 BMS, each control board has two high-frequency switches K1 and K2 to control the bypass and access of the lithium battery module. All lithium battery modules are connected in series due to the disconnection of the high-frequency switch K1 of the control board and the conduction of the high-frequency switch K2.

[0053] The energy storage system meets the following conditions: Condition 1: Assume that the system DC output voltage V DV输 is 768V; it is concluded that the number of battery modules connected to the system in one scanning cycle is 15, and the number of battery modules that can be bypassed is 15; Condition 2: When the system starts charging or discharging, it is assumed that the specific SOH data of 30 battery modules obtained by the EMS controller from the BMS unit before the charging (or discharging) scan cycle are as shown in Table 6 below:

[0054] Condition 3: From condition 2, it can be obtained that if the SOH of the battery modules in the entire system is ≥ 60.0%, all battery modules in the system participate in the charging (or discharging) operation; Condition 4: When the system is charging (or discharging), the SOH of the battery module does not change; Condition 5: When this charge (or discharge) cycle ends, it is assumed that the EMS controller detects the SOH data of the battery module as shown in Table 7 below:

[0055] Condition 6: Before the next charging (or discharging) cycle of the system, according to the data collected in condition 5, the SOH of the battery modules in the entire system is ≥ 60.0%, then all battery modules in the system participate in the operation of the next charging (or discharging) cycle; When the energy storage system has been running for x charging (or discharging) cycles, at the end of a charging (or discharging) cycle, the real-time SOH data of the battery module obtained by the EMS controller is shown in Table 8 below:

[0056] From the above data, we can get: SOH of 1# battery module is less than 60%; Since the energy storage system is charged and discharged continuously, when a battery module SOH < 60.0% is detected after a certain charging (or discharging) cycle, it is impossible for the operator to replace the battery module with SOH < 60.0% immediately. Then the energy storage system will have the following two operating conditions: In the first case, the battery module is not replaced: When the energy storage system is in the (x+1)th charging (or discharging) cycle, according to the collected battery module SOH data, the 1# battery module SOH is less than 60.0%, then the 1# module is permanently bypassed, the K1 switch of the 1# control board remains open, and the K2 switch remains closed, but the EMS controller and the BMS of the 1# battery module are maintained for data exchange.

[0057] The entire system starts from the (x+1)th charging (or discharging) cycle, and only (n-1) battery modules participate in the charging and discharging operation of the energy storage system.

[0058] If the number of battery modules with SOH < 60.0% generated by the subsequent operation of the energy storage system increases and is not replaced, then in the subsequent operation, the battery modules with SOH < 60.0% will be permanently bypassed, and the number of battery modules participating in the system operation will decrease until the number of battery modules participating in the operation is: V1+V2+┅+Va<V DC输 , The entire energy storage system stops running and waits for the battery to be replaced.

[0059] In the second case, the battery module can be replaced without stopping the system: When the energy storage system is in the (x+1)th charging (or discharging) cycle, according to the collected battery module SOH data, the 1# battery module SOH is less than 60.0%, then the 1# module is permanently bypassed, the K1 switch of the 1# control board remains open, and the K2 switch remains closed, but the EMS controller and the BMS of the 1# battery module are maintained for data exchange.

[0060] When an operator is ready to replace the battery without stopping the machine, the operator needs to select the battery to be replaced on the operating platform, click the replacement button, and send an instruction to the EMS controller. When the EMS controller receives the battery replacement instruction from the operating platform, the battery module will continue to be permanently bypassed, the K1 switch of the 1# control board will be disconnected, the K2 switch will remain closed, and the BMS communication between the EMS controller and the 1# battery module will also be disconnected, and no data communication will be carried out with the BMS of the battery; At this point, the entire system continues to operate, but the data of the replaced battery module is no longer updated in the energy storage system; the operator can then replace the battery module; After the battery module is replaced, the operator clicks on the operating platform to confirm that the battery module has been replaced. After the EMS controller receives the replacement completion information, it first releases the data communication with the battery module BMS to perform data detection and comparison. When it is confirmed that the collected battery data is safe and correct, that is, in the next charging (or discharging) cycle, the K1 switch of the control panel of the battery module is closed and the K2 switch is disconnected to participate in the operation of the entire system.

[0061] At this point, the battery module replacement is completed without stopping the energy storage system.

[0062] The method of replacing battery modules without stopping the energy storage system in Examples 3 and 4 can be performed simultaneously with the method of achieving SOC consistency balance of battery modules in the energy storage system in Examples 1 and 2 during the use of the same battery pack.

[0063] Embodiment 5: Embodiment 5 is an extended embodiment of Embodiment 3. The performance control method of the energy storage system of this embodiment is used to achieve battery capacity balancing while replacing battery modules without stopping the energy storage system, thereby solving the technical problems of low utilization rate of battery modules in the energy storage system and low continuous operation efficiency and safety of the energy storage system.

[0064] Among them, this embodiment adopts the method of energy storage system performance control of embodiment 6, that is, the energy storage system includes multiple battery units, EMS controller (including operation platform) and PCS, each battery unit is composed of 1 control board, 1 group of lithium battery modules and 1 BMS, each control board has two high-frequency switches (K1 and K2) to control the bypass and access of lithium battery modules. All lithium battery modules are connected in series due to the disconnection of the high-frequency switch K1 of the control board and the conduction of the high-frequency switch K2. The total voltage output after the series connection is V 输 ; BMS collects the voltage, temperature, current, SOC and other parameters of each lithium battery module, and obtains the real-time capacity, SOC, SOH and other data of the lithium battery module through logical operations, and exchanges data with the EMS controller through communication; The EMS controller mainly performs the system's logical operation algorithm control to achieve stable and safe operation of the energy storage system, intuitively display important data, receive manual operation instructions, and exchange data with the BMS, control board, and PCS; The PCS mainly realizes the AC / DC inverter function of electric energy.

[0065] like Figure 6 As shown, in addition to the control method of Example 3, the performance control method of the energy storage system in this embodiment also includes: Step 1: Collect battery data in the first charge and discharge cycle of the battery to be balanced, preprocess and initialize the battery data, and obtain cycle parameters; Specifically, the battery data in the first charge and discharge cycle of the battery to be balanced is collected. The battery data includes voltage, current, capacity change and battery calibration capacity. After the battery data is collected, missing value processing, data deduplication, outlier processing and data segment cutting and reconstruction are performed on the battery data. Among them, missing value processing: when there are a lot of missing data in the time dimension, a certain data item or all data items in the time period are deleted; when there are only a small amount of missing data in the time dimension, considering the continuity of each parameter data, the interpolation method is used to fill the data to ensure data integrity and data quality; Data deduplication: locate based on time data, sort all data by time, select the first item in the duplicate data to save, and delete the rest of the duplicate data; Abnormal value processing: due to abnormal collection, abnormal communication and other problems, abnormal values ​​that significantly exceed the adjacent data are generated. The processing method is to interpolate based on the adjacent data; if the charging or discharging end data is abnormal, the entire data is directly deleted; Data segment cutting and reconstruction: Data segment cutting and reconstruction is to intercept different data items for classification in different dimensions, and divide the data set into time spans according to the screening conditions.

[0066] After completing the above operations, Collect data at fixed intervals The real-time voltage of each battery constitutes the cycle parameters, which are as follows: ; in, Indicates the specific data sampling time, that is ; Indicates the real-time voltage of the battery to be balanced.

[0067] Step 2: Calculate the current total capacity of the battery and the battery aging coefficient based on the battery data, and then calculate the time of this battery charge and discharge cycle based on the cycle parameters combined with Gaussian regression and extended Kalman filtering; The battery to be balanced starts charging from 0 dehumidification capacity, then: ; in, For the Battery health status at each cycle; is a given charge and discharge current; The rated capacity of the battery to be balanced when it is put into operation; The time required for the battery to be balanced to charge from the initial time 0 to the cut-off voltage; is the aging coefficient.

[0068] As the battery to be balanced continues to charge and discharge, Time has come The battery power changes at all times are: ; in, and for Time has come The internal charge of the battery changes at all times. During this period of time, from Changes to The total capacity of the above formula Calculate and get: ; Based on total capacity , combined with the rated capacity Then we have: ; For loop parameters Perform Gaussian regression and use linear function As the mean function, the square exponential covariance function is selected as the kernel function, and the cycle parameters after Gaussian regression are used as the cycle parameters of the next charge and discharge cycle, that is, , perform extended Kalman filtering to calculate the time of this battery charge and discharge cycle, and update the difference quotient near-view Jacobian matrix in the process of Kalman filtering calculation. The specific formula is as follows: ; ; in, Represents the state matrix, as the identity matrix; Indicates the use of Perform a Gaussian regression process and predict The voltage value, Indicates The observed values ​​of the cycle parameters obtained after Gaussian regression in the charge and discharge cycle are and denote state noise and measurement noise respectively; Extended Kalman filter loop recursion: ; ; in, Represents state noise The covariance of Represents the measurement noise The covariance of Represents the predicted covariance matrix, which is used to represent the covariance of the uncertainty or error of the state estimate; Update the difference quotient approximate Jacobian matrix: ; ; ; ; in, represents the difference quotient approximate Jacobian matrix; Represents the filter gain in the Kalman filter, which combines the observed value and the predicted value to update the state estimate; Indicates The covariance of the sub-cycle estimation errors; Step 3: Use the time of this battery charge and discharge cycle as the time of the next battery charge and discharge cycle and calculate the health status of the battery in combination with the aging coefficient. Calculate the battery balancing time based on the battery health status and the cutoff coefficient. Adjust the charge and discharge time of the battery in the next charge and discharge process based on the balancing time to complete the energy balancing of the battery charge and discharge process.

[0069] The time of this battery charge and discharge cycle is , that is, wait for the balanced battery to be charged from the minimum capacity to The time of the moment, based on this, The full charge time is expressed as: ; Will , and the full charge time is Thus, the full charge time of all cycles is obtained, that is, ; Combined with the aging coefficient, the health status of the battery is calculated: ; Combined with the set charging cut-off coefficient and discharge cut-off coefficient , calculate the battery balancing time; The charge equalization time is calculated by the following formula: ; in, Indicates the charge equalization time; Indicates the amount of power transferred during battery balancing; ; in, express Moment Save the remaining battery power. Indicates the average remaining chargeable capacity of the battery; ; Where N is the number of cycles; The discharge balance time is calculated by the following formula: ; in Indicates the amount of electricity transferred by battery discharge; ; in, Indicates the average discharge capacity of the battery at the end of discharge; ; Where N is the number of cycles.

[0070] Taking a 51.2V280Ah 1p16s battery box as an example, the battery voltage, SOC and other parameter control equalization scheme and the scheme of the present invention are compared and tested, and the equalization effect is shown in Table 9 below:

[0071] The method for replacing battery modules of the energy storage system without stopping the energy storage system in Example 5 can be performed simultaneously with the method for replacing battery modules of the energy storage system without stopping the energy storage system in Examples 3 and 4 during the use of the same battery pack.

[0072] Embodiment 6: like Figure 1 As shown, the energy storage system of this embodiment includes multiple battery units, EMS controller (including operating platform) and PCS. Each battery unit consists of a control board, a group of lithium battery modules and a BMS. Each control board has two high-frequency switches (K1 and K2) to control the bypass and access of the lithium battery module. All lithium battery modules are connected in series due to the disconnection of the high-frequency switch K1 of the control board and the conduction of the high-frequency switch K2. The total output voltage after the series connection is V DC输 ; BMS collects the voltage, temperature, current, SOC and other parameters of each lithium battery module, and obtains the real-time capacity, SOC, SOH and other data of the lithium battery module through logical operations, and exchanges data with the EMS controller through communication; The EMS controller mainly performs the system's logical operation algorithm control to achieve stable and safe operation of the energy storage system, intuitively display important data, receive manual operation instructions, and exchange data with the BMS, control board, and PCS; The PCS mainly realizes the AC / DC inverter function of electric energy.

[0073] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A performance control method for an energy storage system, wherein the energy storage system comprises a plurality of battery modules, characterized in that: The performance control method of the energy storage system comprises the following steps: Periodically reading real-time parameters of the plurality of battery modules through a control system, wherein the real-time parameters include a real-time SOC value and a real-time SOH value; When the read parameter is the real-time SOC value, a consistent balanced discharge operation is performed: Sort multiple battery modules in ascending order according to the real-time SOC values, and select the N battery modules with the lowest ranking as the target module 1; connect the target module 1 to the energy storage system to participate in the discharge, and bypass other battery modules; when the target module 1 is connected to the energy storage system, the real-time total output voltage Vin of the energy storage system is within the preset stable voltage Vstable interval; or When the read parameter is the real-time SOC value, the consistent equalization charging operation is performed: Sort multiple battery modules in ascending order according to the real-time SOC values, and select the top N battery modules as target modules 2; connect the target modules 2 to the energy storage system for charging, and bypass other battery modules; and / or When the parameter read is the real-time SOH value, the battery module replacement operation is performed without stopping the machine: The real-time SOH values ​​of multiple battery modules are judged, and a battery module with a real-time SOH value less than 60.0% is selected as the target module 3; the target module 3 is bypassed, and other battery modules except the target module 3 are connected to the energy storage system to participate in charging or discharging, and then the data communication between the target module 3 and the control system is disconnected, and the target module is replaced; after the replacement is completed, the data communication between the replaced target module 3 and the control system is reconnected, and then the target module 3 group is reconnected to the energy storage system to participate in charging or discharging.

2. The performance control method of the energy storage system according to claim 1, characterized in that: The multiple battery modules are connected in series, and the output voltages V1 of the battery modules are all equal.

3. The performance control method of the energy storage system according to claim 1, characterized in that: When performing a consistent balanced discharge operation, the following conditions must be met: the total stable output voltage of the energy storage system is within the voltage range of the energy storage transformer; when performing a consistent balanced charging operation, the following conditions must be met: the total input voltage of the energy storage system is within the voltage range of the energy storage transformer; when performing a non-stop battery module replacement operation, the following conditions must be met: the total stable output voltage and total input voltage of the energy storage system are within the voltage range of the energy storage transformer.

4. The performance control method of the energy storage system according to claim 1, characterized in that: Periodically reading the real-time SOC values ​​of multiple battery modules, specifically refers to scanning the real-time SOC values ​​of multiple battery modules that are connected to the energy storage system and participating in discharge or charging; periodically reading the real-time SOH values ​​of multiple battery modules, specifically refers to scanning the real-time SOH values ​​of multiple battery modules that participate in discharge or charging after each charging or discharging of the energy storage system.

5. The performance control method of the energy storage system according to claim 1, characterized in that: When performing the operation of replacing a battery module without stopping the machine, the battery data and real-time SOC values ​​of the multiple battery modules are synchronously read, and the battery data is preprocessed and initialized to obtain the cycle parameters; when charging or discharging other battery modules except the target module 3, the following is executed: S1. Calculate the current total capacity of the battery according to the battery data, and calculate the aging coefficient of the battery, and calculate the time of the current charge and discharge cycle of the battery based on the aging coefficient and cycle parameters combined with Gaussian regression and extended Kalman filtering; S2. The time of the current battery charge and discharge cycle is used as the time of the next battery charge and discharge cycle and the battery health status is calculated in combination with the aging coefficient. The battery balancing time is calculated according to the battery health status and a preset cutoff coefficient. The charge and discharge time of the battery in the next charge and discharge process is adjusted based on the balancing time to complete the energy balancing of the battery in the charge and discharge process.

6. The performance control method of the energy storage system according to claim 5, characterized in that: In S1, the battery data includes voltage, current, capacity change and battery rated capacity; The cycle parameters include the real-time voltage of the battery collected at several fixed intervals, and the cycle parameters are obtained based on the voltage in the battery data; the preprocessing operations performed on the battery data include missing value processing, data deduplication, outlier processing, and data segment cutting and reconstruction.

7. The performance control method of the energy storage system according to claim 5, characterized in that: In S1, the current total capacity of the battery is calculated based on the battery data and the battery aging coefficient is further calculated in combination with the battery health formula, including: obtaining the battery charge change during battery charging and discharging based on the current, calculating the current total capacity of the battery in combination with the capacity change, and calculating the battery aging coefficient based on the current total capacity and the battery calibrated capacity.

8. The performance control method of the energy storage system according to claim 7, characterized in that: In S1, the aging coefficient is calculated by the following formula: ； in, is the rated capacity of the battery; Indicates the current total capacity, calculated using the following formula: ； In the formula, and Indicates different moments in the charging or discharging process, For the corresponding The remaining battery capacity; For the corresponding The remaining battery capacity; for The battery current at that moment.

9. The performance control method of the energy storage system according to claim 7, characterized in that: In S1, the calculation of the time of the current battery charge and discharge cycle based on the cycle parameters and the aging coefficient in combination with Gaussian regression and extended Kalman filtering includes: performing Gaussian regression on the cycle parameters, and then using the cycle parameters after Gaussian regression as the cycle parameters of the next charge and discharge cycle to perform extended Kalman filtering to calculate the time of the current battery charge and discharge cycle; the Gaussian regression uses a linear function As the mean function, the squared exponential covariance function was chosen as the kernel function.

10. The performance control method of the energy storage system according to claim 8, characterized in that: In S2, the balancing time includes a charging balancing time and a discharging balancing time, and the cutoff coefficient includes a charging cutoff coefficient and a discharging cutoff coefficient; The charge equalization time is calculated by the following formula: ； in, Indicates the charge equalization time; Indicates the amount of power transferred during battery balancing; Said Calculated by the following formula: ； in, represents the charge cut-off coefficient, express Moment Save the remaining battery power. Indicates the average remaining chargeable capacity of the battery; For the Battery health status at each cycle; is the rated capacity of the battery; Said Calculated by the following formula: ； Where N is the number of cycles; The discharge balance time is calculated by the following formula: ； in Indicates the amount of electricity transferred by battery discharge; Said Calculated by the following formula: ； in, represents the discharge cut-off coefficient; Indicates the average discharge capacity of the battery before discharge; Said Calculated by the following formula: ； Where N is the number of cycles; Said Calculated by the following formula: ； in, Time to fully charge the battery; is a given charge and discharge current; is the aging coefficient.

11. An energy storage system for executing the performance control method according to any one of claims 1 to 10, characterized in that: include: An EMS controller, a plurality of battery cells arranged in series; each battery cell includes a battery module, a control module and a battery management unit, the battery module is connected to the energy storage system through the control module, the battery management unit is used to collect the real-time SOC value, real-time SOH value and battery data of the corresponding battery module, and the EMS controller establishes communication with the control module and the battery management unit respectively; The battery management unit is used to periodically collect the real-time SOC value and real-time SOH value of the battery module and send them to the EMS controller; The EMS controller is used to sort the real-time SOC values ​​of multiple battery modules according to the numerical values ​​when in a discharging state, and select N battery modules with high rankings and large real-time SOC values ​​as target modules 1; And control the corresponding control module to connect the target module 1 to the energy storage system to participate in discharge, and bypass other battery modules; and / or The EMS controller is used to sort the real-time SOC values ​​of multiple battery modules according to the numerical values ​​when in the charging state, select the top N battery modules with small real-time SOC values ​​as the target module 2; and control the corresponding control module to connect the target module 2 to the energy storage system for charging, and bypass other battery modules; and / or The EMS controller is used to judge the real-time SOH values ​​of multiple battery modules when in a charging state or a discharging state, and select a battery module with a real-time SOH value less than 60.0% as the target module 3; and controlling the corresponding control module to bypass the target module 3, and then controlling the corresponding battery management unit to disconnect data communication; and / or The EMS controller is used to control the battery management unit corresponding to the replaced target module to re-establish data communication when in a charging state or a discharging state, and control the corresponding control module to re-connect the replaced target module 3 to the energy storage system to participate in charging or discharging.

12. The energy storage system according to claim 11, characterized in that: The control module includes a K1 high-frequency switch and a K2 high-frequency switch. The positive electrode of the battery module is connected to the emitter of the K1 high-frequency switch, the collector of the K1 high-frequency switch is connected to the emitter of the K2 high-frequency switch, and the collector of the K2 high-frequency switch is connected to the negative electrode of the battery module.

13. The energy storage system according to claim 11, characterized in that: The output voltages of the battery modules are all equal.

14. The energy storage system according to any one of claims 11 to 13, characterized in that: The energy storage system is a cascade energy storage system, and the battery module is a retired lithium battery module.

Images