Method and system for setting use capacity of battery cell of energy storage system

Abstract

The invention discloses a method and a system for setting the use capacity of a battery cell of an energy storage system, relates to the technical field of energy storage system optimization, and solves the problems of low efficiency, limited precision and poor universality existing in the setting of the use capacity of the battery cell in the prior art. The method comprises the following steps: performing full charge and discharge on protection parameters of the energy storage system adapted to conventional battery cluster single cell voltage in a BMS (Battery Management System), recording direct current side electric quantity in a charge process and a discharge process in a second level and a maximum value, a minimum value and an extreme value difference of the battery cluster single cell voltage to obtain a first array, and calculating cell use capacity, according to the method, based on the VOC curve of the battery cell of the high-precision energy storage system and the high-precision electric energy metering mode, the voltage and the electric quantity of the battery cell are highly synchronized in time in the charging and discharging process, and the charging and discharging efficiency of the battery cell is improved. And the use capacity of the battery cell can be accurately and rapidly set, and the universality is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage system optimization, in particular to a method and system for setting the use capacity of an energy storage system. BACKGROUND

[0002] The use capacity of an electric core is the capacity range selected based on the higher efficiency and smaller voltage change of the electric core under the standard conditions (ambient temperature 25℃, charge termination voltage 3.65V, discharge termination voltage 2.5V) and the changed charge and discharge termination conditions (conventional charge termination voltage 3.6V, discharge termination voltage 2.8V), as the use capacity of the energy storage system. Based on the integrated control level of the energy storage system, the optimal method for selecting the use capacity of the electric core is the setting method for the capacity of the electric core of the energy storage system, which is used to maximize the efficiency of the energy storage system, ensure the available capacity of the energy storage system, and prolong the cycle life of the energy storage system. The setting of the use capacity of the electric core of the energy storage system is an optimization method based on the performance of the electric core for the requirements of the system, which is an effective supplement to the production process of the consistency of the electric core in the use stage of the electric core, and the purpose is consistent with the methods such as grading of new electric core capacity, sorting and grouping of PACK, sorting of PACK by battery cluster, and optimal distribution of battery cluster by electric pile. The consistency of the electric core requires high control accuracy in the production stage, and the sorting and grouping of the electric core in the energy storage system stage requires high detection accuracy. The capacity selected in the optimal performance stage is based on the capacity redundancy of the energy storage system, which is the final optimization means of the energy storage system.

[0003] The core defects of the traditional electric core capacity setting method based on fixed cutoff voltage repeated testing and based on time integral calculation of charge and discharge capacity are:

[0004] 1. Low efficiency: time-consuming, energy-consuming, resource-consuming, and difficult to meet the modern high-efficiency production testing requirements.

[0005] 2. Limited precision and instability: affected by polarization, voltage relaxation, current measurement error, integral accumulation error, insufficient coulomb efficiency, self-discharge, temperature change and other factors, the precision is difficult to guarantee and fluctuates greatly.

[0006] 3. Poor universality: poor adaptability to electric cores of different chemical systems, different designs / processes / aging states, and different manufacturers. Parameters (cutoff voltage, test conditions) need to be calibrated and verified separately for each case, lacking universality and robustness. It cannot intelligently adapt to individual differences and state changes of electric cores. SUMMARY

[0007] The present application aims to overcome the problems of low efficiency, limited precision and poor universality in the existing technology of electric core use capacity setting, and provides a method and system for setting the use capacity of an electric core of an energy storage system.

[0008] In a first aspect, a method for setting the capacity of an energy storage system is provided, comprising:

[0009] obtaining parameter information of the energy storage system;

[0010] performing full charging and full discharging on the energy storage system under the protection parameters of the BMS adapted to the voltage of the battery cluster monomer cell, and recording the maximum, minimum and difference of the direct current side electric quantity and the battery cluster monomer cell voltage in the charging and discharging process to obtain a first array;

[0011] calculating the capacity of the cell according to the charging and discharging capacity of the energy storage system direct current side, the nominal voltage of the cell, the number of single PACK cell and the number of PACK at the end of the full charging and full discharging process;

[0012] selecting a second array meeting the preset parameter setting principle from the first array as the setting parameter;

[0013] performing rated power full charging and full discharging using the setting parameter in the second array and recording a third array for verification of the setting parameter.

[0014] In some possible implementations, the parameter information includes the direct current side charging and discharging efficiency, the nominal capacity of the cell, the nominal voltage of the cell, the number of single PACK cell and the number of PACK.

[0015] In some possible implementations, the temperature of the cell of the energy storage system is controlled within a preset temperature range by a temperature control system during the full charging and full discharging process.

[0016] In some possible implementations, the energy storage system that has completed at least two rounds of rated power full charging and full discharging under the protection parameters of the voltage of the conventional battery cluster monomer cell is considered as the cell being activated, and the full charging and full discharging cycle can be stopped.

[0017] In some possible implementations, the energy storage system records an array A=[E 充 , U 大1 , U 小1 , U 极差1 ] during the charging process, where E 充 is the charging capacity of the energy storage system direct current side, U 大1 , U 小1 and U 极差1 represent the maximum, minimum and difference of the battery cluster monomer cell voltage during the charging process, and the energy storage system records an array B=[E 放 , U 大2 , U 小2 , U 极差2 ] during the discharging process, where E 放 is the discharging capacity, U大2 , U 小2 and U 极差2 represent the maximum value, the minimum value and the extreme difference of the battery cluster single cell voltage during discharging, respectively.

[0018] In some possible implementation manners, the condition of E 充 > E0 and E 放 < E0 is met, the calculation formula of the cell use capacity is: C = (E 充 + E 放 ) / 2 / (U0 * X * Y), wherein C is the cell use capacity, E 充 is the charging electric quantity of the direct current side of the energy storage system, E 放 is the discharging electric quantity of the direct current side of the energy storage system, U0 is the nominal voltage of the cell, X is the number of single PACK cells, and Y is the number of PACKs.

[0019] In some possible implementation manners, the preset parameter setting principle includes a cell capacity condition, an extreme value condition of battery cluster single cell voltage and a voltage span level condition.

[0020] The cell capacity condition is:

[0021] C ≥ C0 + C 级 *N;

[0022] C ≤ C0 + C 级 *(N+1);

[0023] wherein C is the optimized cell use capacity, C0 is an initial cell use capacity, C 级 is a cell capacity level, and C is N cell capacity levels higher than C0.

[0024] The extreme value condition of the battery cluster single cell voltage is:

[0025] U 极差 -10XmV ≤ U 极差1 ≤ U 极差 ;

[0026] U 极差 -10XmV ≤ U 极差2 ≤ U 极差 ;

[0027] wherein U 极差 is the optimized battery cluster single cell voltage difference, X is a positive integer, U 极差1 represents the extreme difference of the battery cluster single cell voltage during charging, and U 极差2 represents the extreme difference of the battery cluster single cell voltage during discharging.

[0028] The voltage span level condition is that the voltage 0.025V is the maximum charging voltage U of the battery cluster single cell 大 and the minimum discharging voltage U 小 The second array is selected from the array satisfying the cell capacity condition and the maximum and minimum voltage conditions of the battery cluster single cell.

[0029] In some possible implementations, if the second array contains multiple groups of parameters, the multiple groups of parameters in the second array are used to fine-tune the cell usage capacity.

[0030] In some possible implementations, the setting parameters in the second array are used to perform the rated power full charging and discharging, and a third array is recorded for verification of the setting parameters, including:

[0031] The setting parameters in the second array are input into the BMS system to perform the rated power full charging and discharging, and a third array is recorded, and the system efficiency and the cell usage capacity in the rated power full charging and discharging process are calculated according to the third array to verify the use effect of the setting parameters.

[0032] In the second aspect, a setting system for the cell usage capacity of an energy storage system is provided, which adopts the setting method in the first aspect, and includes a high-voltage box, the high-voltage box is connected with a plurality of battery packs through a bidirectional daisy chain, the high-voltage box is connected with an EMS system and a BMS upper computer, the high-voltage box is connected with an alternating current bus through a PCS system, the alternating current side and the direct current side of the PCS system are connected with a power analyzer, and the EMS system is in communication connection with the PCS system.

[0033] The present application has the following beneficial effects: by unifying the single cell voltage extreme value, the single cell voltage extreme value difference, and the alternating current and direct current side charging and discharging electric quantity second-level data in time during the charging and discharging process of the energy storage system, the cell usage capacity meeting the product requirements of the energy storage system is selected, the cell extreme difference value of the battery cluster at the end of the charging and discharging is reduced, the consistency of the single cell voltage and the charging and discharging capacity in the charging and discharging process is ensured, and a certain capacity performance margin is left on the basis of the product nominal capacity. Compared with the method of setting the cut-off voltage for repeated testing and calculating the charging and discharging capacity according to time to intercept the cell usage capacity, the cell capacity operating range of the energy storage system can be more quickly and accurately set, the charging and discharging cycle number of the energy storage system is greatly prolonged, the consistency of the system charging and discharging capacity is ensured, and the efficiency of the energy storage system is improved. The present method is based on the high-precision energy storage system cell VOC curve and the high-precision electric energy metering mode, so that the voltage and the electric quantity of the cell are highly synchronized in time during the charging and discharging process, the cell usage capacity is accurately and quickly set, and the present method is suitable for the energy storage systems of different cell manufacturers and different cell specifications. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a flowchart of the method for setting the battery cell capacity of the energy storage system according to Embodiment 1 of this application;

[0037] Figure 2 This is a structural block diagram of the energy storage system cell capacity setting system of Embodiment 2 of this application;

[0038] Figure 3 This is a flowchart of the processing of arrays A3 and B3 in Embodiment 2 of this application.

[0039] Figure label:

[0040] 100. High-voltage box; 200. Battery pack; 300. EMS system; 400. BMS host computer; 500. AC bus; 600. Power analyzer; 700. PCS system. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] like Figure 1 As shown in Embodiment 1 of this application, a method for setting the cell capacity of an energy storage system includes:

[0044] S100. Obtain the parameter information of the energy storage system, select the energy storage system for which the cell usage capacity needs to be adjusted, and set the difference between the DC side charging efficiency and discharging efficiency of the energy storage system as k. Specify the nominal capacity (C0), nominal voltage (U0), number of cells per PACK (X), and number of PACKs (Y). The temperature control system ensures that the temperature of the battery cluster cells is stable within the preset temperature range during the full charging and discharging process of the energy storage system at rated power. In this embodiment, the temperature of the battery cluster cells is stabilized at the control target value, and the temperature difference is less than or equal to 2°C.

[0045] S200: The energy storage system is fully charged and discharged using the protection parameters of the BMS adapted to the voltage of the individual cells of the conventional battery cluster. The maximum, minimum, and extreme value differences of the DC side charge and the voltage of the individual cells of the battery cluster are recorded in seconds to obtain the first array.

[0046] In this embodiment, a high-precision power analyzer and a matching current transformer are used to simultaneously monitor the AC and DC side voltages and currents of the energy storage system and perform energy integration settings. The monitoring data is stored at the second level, and the DC side charging capacity E of the energy storage system is recorded. 充 Record the data to obtain array A1=[E 充 Discharge capacity E 放 Record the data to obtain array B1=[E 放 ].

[0047] Use the BMS host computer to monitor the maximum voltage U of individual cells in the battery cluster. 大 Minimum value U 小 Extreme value difference U The range is calculated, and the data is stored at the second level. The energy storage system charging process yields the array A2=[ U 大1 U 小1 U 极差1 The discharge process yields array B2=[ U 大2 U 小2 U 极差2 ].

[0048] Under standard BMS cell voltage protection parameters (discharge cutoff voltage 2.8V, charging cutoff voltage 3.6V), the energy storage system undergoes activation charge-discharge cycles. An energy storage system that has completed two full charge-discharge cycles at rated power under standard system parameters can be considered as having activated cells. The array data recorded in arrays A1 and A2, as well as arrays B1 and B2, are synchronized in time to obtain array A3 = [E]. 充 U 大1 ,U small 1, U极差1 B3 = [E] 放 U 大2 U 小2 U 极差2 ].

[0049] S300, according to the charging capacity and the discharging capacity of the direct current side of the energy storage system at the end of the charging and discharging process, and the nominal voltage of the battery cell, the number of battery cells in a single PACK and the number of PACKs, the use capacity of the battery cell is calculated.

[0050] Specifically, the relationship between the rated capacity (E0) of the energy storage system and the nominal capacity (C0), the nominal voltage (U0), the number of battery cells in a single PACK (X) and the number of PACKs (Y) is as follows:

[0051] E0= C0* U0* X* Y;

[0052] At the end of the charging and discharging process, the relationship between the charging capacity (E 充 ) and the discharging capacity (E 放 ) of the direct current side of the energy storage system and the rated capacity (E0) of the energy storage system is as follows:

[0053] E0=E 充 / k;

[0054] E0=E 放 *k;

[0055] From the above relationship, the following relationship can be obtained:

[0056] E0=(E 充 +E 放 )*k / (k 2 +1);

[0057] Under the charging and discharging conditions, the charging and discharging efficiency k of the system direct current side is greater than or equal to 97.5%, k / (k 2 +1)≈0.5, so we can get:

[0058] E0≈(E 充 +E 放 ) / 2。

[0059] Then the expression of the nominal capacity (C0) of the battery cell is as follows:

[0060] C0=(E 充 +E 放 ) / 2 / (U0* X* Y);

[0061] Under the condition of E

[0062] C=(E 充 +E 放 ) / 2 / (U0* X* Y);

[0063] S400, filtering a second array meeting a preset parameter setting principle from the first array as a setting parameter.

[0064] The preset parameter setting principle includes a battery cell capacity condition, an extreme value condition of a battery cluster single battery cell voltage, and a voltage span level condition.

[0065] The battery cell capacity condition: C value can be selected according to the battery cell capacity level C level (2 Ah) to select N (2-3) levels higher than C0 as the optimal, that is, to meet the following range:

[0066] C≥C0+C 级 *N;

[0067] C≤C0+C 级 *(N+1);

[0068] The extreme value condition of the battery cluster single battery cell voltage: the single voltage extreme difference U 极差 The 10 mV level is divided, and the 10 mV, 20 mV, 30 mV, 40 mV, and 50 mV levels are selected from U 极差1 and U 极差2 are less than or equal to U 极差 , that is:

[0069] U 极差 -10mV ≤U 极差1 ≤U 极差 ;

[0070] U 极差 -10mV ≤U 极差2 ≤U 极差 .

[0071] The voltage span level condition: the charging voltage maximum value Umax and the discharging voltage minimum value Umin of the battery cluster single battery cell are selected as the screening level with the voltage 0.025 V, and the array meeting the condition is selected from the array meeting the battery cell capacity condition and the extreme value condition of the battery cluster single battery cell voltage as the second array.

[0072] In the screening of the setting parameter, first, the E 充 group meeting the battery cell capacity condition is taken out from the array A3 and B3, and the following array is obtained by combining E 放 :

[0073] A=[ U 大1 , U 小1 , U 极差1 ];

[0074] B=[ U 大2 , U 小2 , U 极差2 ];

[0075] Then, extract the U values ​​from arrays A and B that satisfy the extreme value conditions of the individual cell voltages in the battery cluster. 极差1 with U 极差2 The resulting array AB is as follows:

[0076] AB=[U 大 U 小 ];

[0077] Among them, U 大 U 小 U in array A, which simultaneously satisfies the cell capacity condition and the extreme value condition of the individual cell voltage in the battery cluster. 大1 and U in B 小2 ;

[0078] Finally, the maximum charging voltage U of a single battery cell is set at 0.025V. 大 and the minimum discharge voltage U 小 The filtering level is used to select arrays AB'=[U] that meet the conditions from array AB. 大 ', U 小 ').

[0079] S500. Using the setting parameters in the second array, perform full charge and discharge at rated power and record the results in a third array for verification of the setting parameters. The third array can be an array recorded in the second round of full charge and discharge cycle at rated power, or an array recorded in the second and third rounds of full charge and discharge cycle at rated power, or an array recorded in the second, third, ... and Nth rounds of full charge and discharge cycle at rated power, where N is a positive integer.

[0080] Specifically, the energy storage system undergoes three full-charge-discharge cycles at rated power, and second-level operating data is recorded. The data from the first cycle is used to set the cell operating capacity, resulting in AB'=[U 大 ', U 小 The latter two rounds are performed at rated power for full charging and discharging according to the set parameters, and the data is recorded as verification data for the set parameters. That is, the set parameters in array AB' are input into the BMS system for full charging and discharging at rated power, and the data is recorded in a third array as verification data. The system efficiency and cell capacity used during the full charging and discharging process at rated power are calculated based on the third array to verify the effectiveness of the set parameters. Cells in the same batch can all have their system parameters set according to the set parameters. If array AB' contains multiple sets of parameters, the cell capacity can be finely adjusted.

[0081] The setting parameters in the second array are input into the BMS system to perform a full charge and discharge at rated power and the results are recorded in the third array. The system efficiency and cell capacity used during the full charge and discharge process at rated power are calculated based on the third array to verify the effectiveness of the setting parameters.

[0082] In the present embodiment, by unifying the single cell voltage extreme value, single cell voltage extreme value difference, AC and DC side charge and discharge power second-level data in time during the charge and discharge process of the energy storage system, the battery cell usage capacity meeting the product requirements of the energy storage system is selected, the battery cluster at the end of charge and discharge is reduced, the consistency of the single cell voltage and the charge and discharge capacity in the charge and discharge process is ensured, and a certain capacity performance margin is left on the basis of the nominal capacity. Compared with the method of setting the cut-off voltage for repeated testing and calculating the charge and discharge capacity according to time to intercept the battery cell usage capacity, the energy storage system battery cell capacity operating range can be set more quickly and accurately, the energy storage system charge and discharge cycle number is greatly extended, the system charge and discharge consistency is ensured, and the energy storage system efficiency is improved. The present embodiment is based on the high-precision energy storage system battery cell VOC curve and the high-precision electric energy metering method, so that the voltage and power of the battery cell are highly synchronized in time during the charge and discharge process, the battery cell usage capacity is accurately and quickly set, and the energy storage system of different battery cell manufacturers and different battery cell specifications is applicable.

[0083] Embodiment 2

[0084] As shown in Figure 2 , the present application embodiment 2 relates to a kind of energy storage system battery cell usage capacity setting system, using the setting method described in embodiment 1, the setting system includes high pressure box 100, the high pressure box 100 is connected with several battery packs 200 by bidirectional daisy chain, the high pressure box 100 is connected with EMS system 300 and BMS host computer 400, the high pressure box 100 is connected with alternating current bus 500 by PCS system 700, the alternating current side and the direct current side of the PCS system 700 are connected with power analyzer, the EMS system 300 is connected with communication with PCS system 700.

[0085] The following is an example to illustrate the setting process of the energy storage system battery cell usage capacity:

[0086] The energy storage system uses single cell nominal capacity 280Ah battery cell, the direct current side scheme is 5 1P52S battery PACK in series, configures high pressure box 100 and BMS system, uses high-precision power analyzer and matching current transformer to monitor energy storage system alternating current, direct current voltage and current simultaneously, and carries out charge and discharge power two-way integration setting. After fresh battery cell is charged and discharged, according to the charging single cell cut-off voltage 3.6V, the discharging single cell cut-off voltage 2.8V, the rated power full charge full discharge cycle is carried out, and the energy storage system needs to be static for 30min when charging state is converted. Charging power E 充 , discharging power E 放 is stored in power analyzer, single cell voltage maximum U 大 , minimum U 小 , extreme difference U 极差The data stored in the BMS host computer 400 are all stored in seconds. After the first charge and discharge cycle, the second-level bidirectional power data stored by the power analyzer is matched with the second-level cell data stored by the BMS host computer 400 in the table with the charge and discharge start and stop state as the mark, and the BMS charge and discharge cutoff voltage parameter is set according to the parameter setting method, and the optimal cell capacity range is selected. During the charging and discharging process, the charging and discharging power is the rated power 105kW of the energy storage system, the cell charging and discharging temperature range is controlled at 31℃-34℃, the cell temperature difference is less than or equal to 2℃, and the environment temperature is 25℃, so that the charging efficiency and discharging efficiency difference of the energy storage system can be ignored.

[0087] The data collection and arrangement are as follows:

[0088] The charging power data recorded by the power analyzer is arranged as an array A1=[E 充 ], and the discharging power data is arranged as an array B1=[E 放 ].

[0089] The maximum voltage U 大 , the minimum voltage U 小 , and the voltage difference U 极差 of the single cell recorded by the BMS host computer 400 are arranged as an array A2=[U 大1 , U 小1 , U 极差1 ], and the charging process data is arranged as an array B2=[U 大2 , U 小2 , U 极差2 ].

[0090] A1 and A2 are arranged as an array A3=[E 充 , U 大1 , U 小1 , U 极差1 ] in seconds with the charging start and stop mark.

[0091] B1 and B2 are arranged as an array B3=[E 放 , U 大2 , U 小2 , U 极差2 ] in seconds with the discharging start and stop mark.

[0092] The first round of full and empty direct current of the energy storage system is selected in this embodiment, as shown in Table 1:

[0093] Table 1: First round of full and empty direct current of the energy storage system

[0094]

[0095] C=(E 充 +E放 The cell capacity C can be calculated as 293.2Ah by using (U0* X* Y) / 2 / (U0* X* Y).

[0096] C represents the cell's usable capacity at a discharge cutoff voltage of 2.8V and a charging cutoff voltage of 3.6V.

[0097] E 充 =250.16kWh is the initial charging capacity;

[0098] E 放 =237.78kWh is the amount of electricity discharged in the first round;

[0099] U0=3.2V is the nominal voltage of the battery cell selected in this scheme;

[0100] X=52 represents the number of cells in a single PACK;

[0101] Y=5 represents the number of battery packs.

[0102] The setting of the cutoff voltage parameters of the charging and discharging cells of the energy storage system must follow the following preset parameter setting principles:

[0103] 1) The cell capacity C can be selected 2-3 levels higher than C0 (280Ah) based on the cell capacity level (2Ah). In this scheme, C=286Ah is selected. The selection of C value takes into account that the cell capacity meets C≥C0 and minimizes the voltage difference between individual cells at the end of charging and discharging, so as to ensure the consistency of individual cell voltages during charging and discharging of the battery cluster and the certainty of the system's charging and discharging quantity, and improve the charging and discharging efficiency of the DC system.

[0104] Select cells with a capacity of 286Ah, and configure arrays A3 and B3 according to E. 充 >E0, E 放 <E0, 284Ah≤C≤286Ah, E0=232.96kWh, screening E 充 E 放 The array A = [U_large1, U_large1, U_large1] is obtained. 小1 U 极差1 ],B=[ U 大2 U 小2 U 极差2 ].

[0105] 2) While ensuring the usable capacity of the battery cells, guarantee that the charging and discharging ends of the battery cluster simultaneously meet U... 极差1 with U 极差2 Within the same range of individual cell voltage extreme differences, the individual cell voltage extreme difference value U 极差 Divided into 10mV levels, it can be categorized into 10mV, 20mV, 30mV, 40mV, and 50mV levels. This solution uses U... 极差1 with U 极差2At the same time, the pressure difference interval greater than 30 mV and less than 40 mV, the array A, B can be combined as array AB = [U 大 , U 小 ], wherein U 大 is taken from U 大1 in array A, U 小 is taken from U 小2 in array B.

[0106] 3) The array AB = [U 大 , U 小 ] is selected from the array AB by 0.025V voltage span level to obtain the setting parameters, and if the AB' contains multiple groups of parameters, the capacity of the battery cell can be fine-tuned.

[0107] The data obtained by the first round of charge and discharge and the preset parameter setting principle are used to process the array A3 and the array B3, as shown in Figure 3 .

[0108] After obtaining the setting parameters AB', the battery cell monomer discharge cutoff voltage is selected as 2.95V and the charge cutoff voltage is selected as 3.5V, the setting parameters are input into the BMS system, and the subsequent charge and discharge verification is used to verify the use effect of the setting parameters, and the charge and discharge data are shown in Table 2.

[0109] Table 2: Charge and discharge data

[0110]

[0111] By comparing the charge and discharge data, the direct current side system efficiency is improved from 95.05% in the first round of charge and discharge to 95.64% in the second round and 95.68% in the third round, and the subsequent two rounds of charge and discharge capacity and system efficiency stability are greatly improved. The battery cell usage capacity in the second round of charge and discharge is 285.5Ah, and the battery cell usage capacity in the third round is 285.6Ah, which achieves the purpose and effect of battery cell usage capacity setting.

[0112] According to the performance of the battery cell usage capacity under the conventional parameters, the priority of the input battery cell usage capacity and the input range of the difference value in the parameter setting principle can be exchanged, at this time, the following parameter setting conditions should be followed:

[0113] 1) U 极差1 and U 极差2 satisfy the pressure difference interval greater than or equal to 20mV and less than or equal to 30mV, or greater than or equal to 40mV and less than or equal to 50mV, at this time, C should not be less than C0 (280Ah), and C should not be greater than 293.2Ah under the conventional setting parameters (discharge monomer cutoff voltage 2.8V, charge cutoff voltage 3.6V),

[0114] 2) The selection principle of the voltage level of array AB, the voltage span can be selected according to the extreme voltage width of U 大 小 The voltage span level should be greater than 0.005V to avoid the influence of BMS single cell voltage detection accuracy on parameter setting; and there are at least 3 voltage level points within the extreme voltage width of U 大 小 The voltage span level should be greater than 0.005V to avoid the influence of BMS single cell voltage detection accuracy on parameter setting; and there are at least 3 voltage level points within the extreme voltage width of U

[0115] In this embodiment, the selection of cell capacity level and single cell voltage difference level is based on the cell capacity, the detection data accuracy of the charging and discharging equipment, the actual voltage difference of the cell, and the rules of the industry convention. If the cell capacity, manufacturer, or cell operating conditions are changed, the parameter setting conditions can be adjusted appropriately. Changes in the parameter setting conditions do not affect the use of this setting method under the setting principle.

[0116] It should be noted that other specific embodiments of the setting system of the energy storage system cell usage capacity in this embodiment can refer to the specific embodiments of the energy storage system cell usage capacity setting method described above. To avoid redundancy, this will not be repeated here.

[0117] The above is only a preferred specific embodiment of the present application; however, the protection scope of the present application is not limited thereto. Any person skilled in the art can make equivalent replacements or changes to the technical solutions and improved concepts of the present application within the technical scope disclosed by the present application, which should be covered by the protection scope of the present application.​​

Claims

1. A method for setting the capacity of a battery cell in an energy storage system, characterized in that, The method comprises: obtaining parameter information of the energy storage system; performing full charging and full discharging on the energy storage system under the protection parameters of the BMS which are adapted to the regular battery cluster cell voltage, and recording the maximum, minimum and difference of the direct current side electric quantity and the battery cluster cell voltage in the charging and discharging process in seconds to obtain a first array; calculating the cell usage capacity according to the charging and discharging capacity of the energy storage system direct current side, the nominal voltage of the cell, the number of single PACK cells and the number of PACK during the full charging and discharging process; selecting a second array meeting the preset parameter setting principle from the first array as the setting parameter; performing rated power full charging and full discharging using the setting parameter in the second array and recording a third array for verification of the setting parameter.

2. The method of setting the energy system electric core usage capacity according to claim 1, characterized in that, The parameter information includes direct current side charging and discharging efficiency, cell nominal capacity, cell nominal voltage, number of single PACK cells and number of PACK.

3. The method of setting the energy system electric core usage capacity according to claim 1, characterized in that, The cell temperature of the energy storage system is controlled within a preset temperature range by a temperature control system during the full charging and full discharging process.

4. The method of setting the energy system electric core usage capacity according to claim 1, characterized in that, The energy storage system which has completed at least two rounds of rated power full charging and full discharging under the protection parameters of the regular battery cluster cell voltage is considered as the cell being activated, and the full charging and full discharging cycle can be stopped.

5. The method of setting the energy system electric core usage capacity according to claim 1, characterized in that, The energy storage system records an array A=[E 充 , U 大1 , U 小1 , U 极差1 ] during the charging process, wherein E 充 is the charging electric quantity of the direct current side of the energy storage system, U 大1 , U 小1 and U 极差1 respectively represent the maximum value, the minimum value and the extreme difference of the cell voltage of the battery cluster during the charging process, the energy storage system records an array B=[E 放 , U 大2 , U 小2 , U 极差2 ] during the discharging process, wherein E 放 is the discharging electric quantity, U 大2 , U 小2 and U 极差2 respectively represent the maximum value, the minimum value and the extreme difference of the cell voltage of the battery cluster during the discharging process.

6. The method of setting the energy system electric core usage capacity according to claim 1, characterized in that, In the case of E 充 >0 and E 放 <0, the calculation formula of the cell usage capacity is: C= (E 充 + E 放 ) / 2 / (U0* X* Y), wherein C is the cell usage capacity, E 充 is the charging electric quantity of the direct current side of the energy storage system, E 放 is the discharging electric quantity of the direct current side of the energy storage system, U0 is the nominal voltage of the cell, X is the number of single PACK cells, and Y is the number of PACKs.

7. The method of setting the energy system electric core usage capacity according to claim 5, characterized in that, The preset parameter setting principle includes cell capacity condition, cell voltage extreme condition and voltage span level condition. The cell capacity condition is: C ≥ C0+ C 级 N; C≤ C0+ C 级 (N+1); Wherein, C is the optimized battery cell usage capacity, C0 is the initial battery cell usage capacity, C 级 is the battery cell capacity level, C is higher than C0 by N battery cell capacity levels; The cell voltage extreme condition is: U 极差 -10XmV ≤U 极差1 ≤U 极差 ; U 极差 -10XmV ≤ U 极差2 ≤ U 极差 ; wherein U 极差 is the optimized difference between the maximum and minimum cell voltages of the battery cluster, X is a positive integer, and U 极差1 represents the difference between the maximum and minimum cell voltages of the battery cluster during charging, U 极差2 represents the difference between the maximum and minimum cell voltages of the battery cluster during discharging. The voltage span level condition is that the voltage 0.025 V is the maximum charging voltage U of the battery cluster single battery cell 大 and the minimum discharging voltage U 小 The screening level, and the array that meets the conditions is selected as the second array from the array that meets the cell capacity condition and the maximum and minimum voltage conditions of the battery cluster single battery cell.

8. The method of setting the energy system electric core usage capacity according to claim 1, characterized in that, If the second array contains multiple sets of parameters, the multiple sets of parameters in the second array are used to fine-tune the cell usage capacity.

9. The method of setting the energy system electric core usage capacity according to claim 1, characterized in that, Performing rated power full charging and full discharging using the setting parameter in the second array and recording a third array for verification of the setting parameter, comprising: Inputting the setting parameter in the second array into the BMS system to perform rated power full charging and full discharging and record a third array, and calculating the system efficiency and cell usage capacity during the rated power full charging and full discharging process according to the third array to verify the use effect of the setting parameter.

10. A system for setting the usage capacity of an energy storage system cell, characterized by, The setting method according to any one of claims 1-9, wherein the setting system comprises a high-voltage box connected with a plurality of battery packs through a bidirectional daisy chain, the high-voltage box is connected with an EMS system and a BMS upper computer, the high-voltage box is connected with an alternating current bus through a PCS system, the alternating current side and the direct current side of the PCS system are connected with a power analyzer, and the EMS system is in communication connection with the PCS system.

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