CN110988699A - State diagnosis method and device for echelon utilization of lithium battery energy storage unit - Google Patents

State diagnosis method and device for echelon utilization of lithium battery energy storage unit Download PDF

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Publication number
CN110988699A
CN110988699A CN201911420047.2A CN201911420047A CN110988699A CN 110988699 A CN110988699 A CN 110988699A CN 201911420047 A CN201911420047 A CN 201911420047A CN 110988699 A CN110988699 A CN 110988699A
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China
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storage unit
energy storage
lithium battery
dispersion
voltage
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卢梦瑶
董锐锋
赵光金
王放放
胡玉霞
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State Grid Corp of China SGCC
China Three Gorges University CTGU
Electric Power Research Institute of State Grid Henan Electric Power Co Ltd
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State Grid Corp of China SGCC
China Three Gorges University CTGU
Electric Power Research Institute of State Grid Henan Electric Power Co Ltd
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Priority to CN201911420047.2A priority Critical patent/CN110988699A/en
Publication of CN110988699A publication Critical patent/CN110988699A/en
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/378Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] specially adapted for the type of battery or accumulator
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/385Arrangements for measuring battery or accumulator variables
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/396Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery

Abstract

The application relates to a state diagnosis method and a state diagnosis device for utilizing a lithium battery energy storage unit in a gradient manner, wherein the diagnosis steps are as follows: the method comprises the steps of carrying out cyclic charge and discharge on the lithium battery energy storage unit, calculating the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at a 100% SOC point and the open-circuit voltage dispersion at a 0% SOC point of each monomer under different cycle times, respectively carrying out correlation analysis on the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at the 100% SOC point and the open-circuit voltage dispersion at the 0% SOC point of the same monomer battery under different cycle times and the residual capacity of the lithium battery energy storage unit, and the correlation analysis is carried out on the charge cut-off voltage range and the discharge cut-off voltage range of the energy storage unit under different cycle times and the residual capacity thereof, the characterization index with high correlation with the capacity of the energy storage unit is screened out, and judging the residual capacity of the energy storage unit according to the relation between the characterization index and the capacity, and finishing the on-site accurate evaluation of the echelon utilization lithium battery energy storage unit.

Description

State diagnosis method and device for echelon utilization of lithium battery energy storage unit
Technical Field
The application belongs to the technical field of lithium batteries, and particularly relates to a state diagnosis method and device for utilizing a lithium battery energy storage unit in a gradient manner.
Background
The development of new energy automobiles is an important transformation direction of the automobile industry in China towards energy cleaning, in recent years, the electric automobile industry in China enters a rapid development period, the sales volume of electric automobiles in China from 2011 to 2018 is in a rapid growth trend, correspondingly, the shipment volume of power batteries of electric automobiles also keeps a high-speed growth situation, and the shipment volume of power batteries in 2018 reaches 65 GWH. Thanks to the support of national technology and industry, lithium batteries such as lithium iron phosphate batteries and ternary lithium batteries occupy the mainstream position in the power battery market in recent years.
Because the power lithium battery has the advantages of good safety, long cycle life and the like, most of retired lithium batteries still have higher residual energy and use value, and if a proper application occasion can be found, the echelon utilization of the power lithium battery can be realized. Through the echelon utilization to the different technical performance stages of power lithium cell, can let power battery's performance obtain abundant performance, effectively reduce the cost that power battery is applied to the electric automobile field, prolong the life of whole battery.
The gradient utilization of the retired power lithium battery mainly solves the following two problems: firstly, evaluating whether the retired power lithium battery can be used in a echelon mode; and secondly, the retired lithium battery can provide a certain use value in the echelon utilization. Considering that the performance dispersion of the retired lithium power battery is large, the states of all batteries cannot be evaluated in a similar new battery sampling inspection mode, and the inspection must be carried out one by one. The traditional evaluation method for the state of the retired power lithium battery is similar to the evaluation of a new battery, mainly tests external characteristics such as capacity characteristics, energy characteristics, impedance characteristics, rate characteristics, high and low temperature charge and discharge characteristics, self-discharge characteristics and service life characteristics of the battery, disassembles partial batteries, researches internal defects of the battery and performance conditions of components of the battery, and finally evaluates the state of the retired power battery of the electric automobile by combining analysis results of the internal and external characteristics of the battery. Therefore, it is necessary to research the field diagnosis technology of the battery energy storage unit used in the echelon to guide the echelon to use the energy storage power station to operate safely and stably.
Generally, the health condition of a lithium battery is estimated by a model, and the lithium battery health condition estimation models researched by the existing literature mainly include an electrochemical model, an equivalent circuit model and an empirical model, for example: a lithium ion battery capacity degradation empirical model [ J ]. Power technology, 2016, (6) 1176 + 1179] gives the relation between the internal impedance and the capacity degradation of the battery, and provides a conditional three-parameter capacity degradation empirical model for preferentially determining an integer variable according to the capacity degradation rate; according to the literature [ open congealing, expanding winter, sheath, and the like ], a lithium ion battery residual life prediction method based on a particle filter algorithm is researched [ J ] high technology communication, 2017, (8): 699-. As described above, although certain results are obtained for the evaluation of the health state of the battery and the model research thereof, the evaluation of the health state of the power lithium battery pack cannot be performed quickly and accurately, and thus, the evaluation is not suitable for on-site detection and analysis.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the state diagnosis method and device for the lithium battery energy storage unit in the echelon utilization mode are provided for solving the technical problem that an existing lithium battery pack health condition evaluation model is not suitable for on-site detection and analysis due to the fact that rapid and accurate evaluation cannot be achieved.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a state diagnosis method for utilizing a lithium battery energy storage unit in a gradient manner comprises the following steps:
the method comprises the steps of carrying out cyclic charging and discharging on a lithium battery energy storage unit to be detected, calculating the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at a 100% SOC point and the open-circuit voltage dispersion at a 0% SOC point of each single battery in the lithium battery energy storage unit under different cycle times, then respectively carrying out correlation analysis on the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at the 100% SOC point and the open-circuit voltage dispersion at the 0% SOC point of the same single battery under different cycle times and the residual capacity of the lithium battery energy storage unit to be detected under corresponding cycle times, respectively carrying out correlation analysis on the charge cut-off voltage range and the discharge cut-off voltage range of the lithium battery energy storage unit to be detected under different cycle times and the residual capacity of the lithium battery energy storage unit to be detected under corresponding cycle times, and screening out a characterization, and judging the residual capacity of the lithium battery energy storage unit to be tested according to the relation between the characterization index and the capacity.
Preferably, the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at the 100% SOC point, and the open-circuit voltage dispersion at the 0% SOC point of the same single battery subjected to correlation analysis with the remaining capacity of the lithium battery energy storage unit to be tested at the corresponding cycle number are the maximum charge cut-off voltage dispersion, the maximum discharge cut-off voltage dispersion, the open-circuit voltage dispersion at the maximum 100% SOC point, and the open-circuit voltage dispersion at the maximum 0% SOC point, respectively.
Preferably, the characterization index with high relevance to the capacity of the energy storage unit of the lithium battery to be tested is the dispersion of the charging cut-off voltage or the extreme difference of the charging cut-off voltage.
Preferably, the correlation analysis is a linear correlation coefficient analysis, and the correlation is high.
Preferably, the lithium battery is a lithium iron phosphate battery or a ternary lithium iron battery.
Preferably, the cyclic charge and discharge method comprises the following steps: and discharging the residual electric quantity of the lithium battery energy storage unit to be tested, carrying out constant current charging to the lithium battery energy storage unit after the electric quantity is discharged to reach the upper limit voltage, then carrying out constant voltage charging until the current is reduced to be lower than the lower limit current, standing, and then stopping discharging when the current is discharged to reach the lower limit voltage by adopting a constant current discharging mode.
Preferably, the upper limit voltage is 3.6-4.2V, and the lower limit voltage is 2.8-3.0V.
Preferably, the current for constant current charging is 0.2-0.4C, the lower limit current is 0.05C, and the current for constant current discharging is 0.4-0.6C.
Preferably, the rest time of the lithium battery energy storage unit to be tested is 20-40 minutes after the residual electric quantity of the lithium battery energy storage unit to be tested is discharged and then needs to be placed for 10-20 minutes.
The application also provides a diagnostic device for utilizing the lithium battery energy storage unit in a gradient manner, which comprises:
the dispersion and cut-off voltage range acquiring unit is used for acquiring the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at a 100% SOC point and the open-circuit voltage dispersion at a 0% SOC point of a single battery in the lithium battery energy storage unit to be tested under different charge and discharge cycle times, and the charge cut-off voltage range and the discharge cut-off voltage range of the lithium battery energy storage unit to be tested under different charge and discharge cycle times;
the lithium battery energy storage unit capacity characterization index acquisition unit acquires a characterization index with high correlation with the capacity of the lithium battery energy storage unit to be detected through correlation analysis of charge cut-off voltage dispersion, discharge cut-off voltage dispersion, open-circuit voltage dispersion at a 100% SOC point and open-circuit voltage dispersion at a 0% SOC point of the same single battery and the residual capacity of the lithium battery energy storage unit to be detected;
and the battery pack residual capacity acquisition unit is used for judging the residual capacity of the lithium battery energy storage unit to be tested according to the relation between the characterization index with high capacity relevance with the lithium battery energy storage unit to be tested and the capacity.
The invention has the beneficial effects that:
the invention relates to a state diagnosis method for a lithium battery energy storage unit by utilizing echelon, which mainly calculates the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion of a 100% SOC point and the open-circuit voltage dispersion of a 0% SOC point of each single battery in the lithium battery energy storage unit to be tested under different charge-discharge cycle times, and carries out correlation analysis on the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion of the 100% SOC point and the open-circuit voltage dispersion of the 0% SOC point of the same single battery under different cycle times, and screens out a characterization index for accurately evaluating the capacity of the lithium battery energy storage unit, thereby giving an accurate conclusion whether an energy storage battery pack can continue to normally run or not by utilizing echelon on site according to the characterization index, the characterization index is obtained quickly, and the nondestructive diagnosis and the field evaluation of the health state of the lithium battery energy storage unit used in the echelon mode can be completed through the characterization index data.
Drawings
The technical solution of the present application is further explained below with reference to the drawings and the embodiments.
Fig. 1 is a curve of charging voltage over time for 8 individual batteries using an energy storage unit of a lithium iron phosphate battery (1# battery pack) in a stepwise manner during a first charge-discharge cycle;
fig. 2 is a graph of discharge voltage versus time for 8 cells that use a lithium iron phosphate battery energy storage unit (1# battery) in a stepped manner during a first charge-discharge cycle;
fig. 3 is the open circuit voltage at 0% SOC point in the first charge-discharge cycle for 8 cells using a lithium iron phosphate battery energy storage unit (1# battery) in steps;
fig. 4 is the open circuit voltage at 100% SOC point in the first charge-discharge cycle for 8 cells using a lithium iron phosphate battery energy storage unit (1# battery) in steps;
fig. 5 is a correlation analysis of maximum charge cut-off voltage dispersion of an energy storage unit (1# battery pack) of a lithium iron phosphate battery in a stepped manner and the capacity of the energy storage unit of the corresponding cycle number;
fig. 6 is a correlation analysis of the maximum discharge cut-off voltage dispersion of the lithium iron phosphate battery energy storage unit (1# battery pack) in a gradient manner and the energy storage unit capacity of the corresponding cycle number;
fig. 7 is a correlation analysis of the open-circuit voltage dispersion at the maximum 0% SOC point of a lithium iron phosphate battery energy storage unit (1# battery pack) in a stepped manner and the energy storage unit capacity of the corresponding cycle number;
FIG. 8 is a correlation analysis of the charge cut-off voltage range of an energy storage unit (1# battery pack) utilizing lithium iron phosphate batteries in a stepped manner and the capacity of the energy storage unit corresponding to the number of cycles;
fig. 9 is a correlation analysis of the discharge cut-off voltage range of an energy storage unit (1# battery pack) of a lithium iron phosphate battery in a stepped manner and the capacity of the energy storage unit of the corresponding cycle number;
fig. 10 is a correlation analysis of the maximum charge cut-off voltage dispersion of the ternary lithium iron battery energy storage unit (2# battery pack) used in a gradation manner and the energy storage unit capacity of the corresponding cycle number;
fig. 11 is a correlation analysis of the maximum discharge cut-off voltage dispersion of the ternary lithium iron battery energy storage unit (2# battery pack) used in a gradation manner and the energy storage unit capacity of the corresponding cycle number;
fig. 12 is a correlation analysis of the open-circuit voltage dispersion at the maximum 0% SOC point of a ternary lithium battery energy storage unit (2# battery pack) used in a stepped manner and the energy storage unit capacity of the corresponding cycle number;
FIG. 13 is a correlation analysis of the charge cut-off voltage range of a three-way lithium battery energy storage unit (No. 2 battery pack) used in a stepped manner and the capacity of the energy storage unit corresponding to the number of cycles;
fig. 14 is a correlation analysis of the discharge cut-off voltage range of the three-way lithium battery energy storage unit (2# battery pack) used in a stepped manner and the capacity of the energy storage unit corresponding to the cycle number.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
The technical solutions of the present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Example 1
The embodiment provides a state diagnosis method for utilizing an energy storage unit of a lithium iron phosphate battery in a gradient manner, which comprises the following steps:
(1) the method comprises the following steps of carrying out cyclic charge and discharge on an energy storage unit (No. 1 battery pack) of a lithium iron phosphate battery in a gradient manner, wherein the energy storage unit comprises 8 series-connected single batteries, the batteries of the battery pack are respectively numbered as No. 1-8, and the charge and discharge method comprises the following steps: discharging the residual electricity of the battery at room temperature (20 +/-5 ℃), standing for 15 minutes, performing constant current charging at 0.3 ℃ until the voltage is reduced to 3.65V, converting the constant current charging into constant voltage charging until the charging current is reduced to 0.05C, standing for 30 minutes, and then performing constant current discharging at 0.5C until the voltage is reduced to 2.8V;
as can be seen from fig. 1, in the first charge/discharge cycle, the No. 8 cell reaches the charge cut-off voltage first, and the charge cut-off voltage of the No. 8 cell is maximum and is 3.65V, and the average charge cut-off voltage of the No. 8 cell is 3.49V, and the charge cut-off voltage of the No. 1 cell is minimum and is 3.449V, then in this cycle, the dispersion of the charge cut-off voltage of the No. 8 cell is (3.65-3.49)/3.49-4.5%, the dispersion of the charge cut-off voltage of the No. 8 cell is maximum, the charge cut-off voltage range of this cycle is 3.65V-3.449V-0.201V, actually, in each subsequent charge/discharge cycle, the dispersion of the charge cut-off voltage and the charge cut-off voltage of the No. 8 cell is always maximum, and thus the dispersion of the charge/discharge cut-off voltage of the No. 8 cell in each charge/discharge cycle can be calculated, and calculating the charge cut-off voltage range in each charge-discharge cycle; (ii) a
As can be seen from fig. 2, in the first charge and discharge cycle, the No. 8 cell reaches the discharge cut-off voltage first, and the discharge cut-off voltage of the No. 8 cell is 2.493V, while the average discharge cut-off voltage of the No. 8 cells is 3V, and the discharge cut-off voltage of the No. 1 cell is the maximum, and is 3.147V, then in this cycle, the discharge cut-off voltage dispersion of the No. 8 cell is (3-2.493)/3-0.169, the discharge cut-off voltage dispersion of the No. 8 cell is the maximum, the charge cut-off voltage range of this cycle is 3.147V-2.493V-0.654V, actually, in each subsequent charge and discharge cycle, the discharge cut-off voltage of the No. 8 cell is always the minimum, and the discharge cut-off voltage dispersion is always the maximum, thereby the discharge cut-off voltage dispersion of the No. 8 cell in each charge and discharge cycle can be calculated, and can calculate the discharge cut-off voltage range in each charge-discharge cycle;
fig. 3 and 4 show the open circuit voltage values of 8 series-connected single batteries at 100% SOC and 0% SOC, the dispersion of the open circuit voltage of each single battery at 0% SOC in each charge and discharge cycle can be calculated by the open circuit voltage value of 0% SOC of 8 single batteries in each charge and discharge cycle and the dispersion of the open circuit voltage of each single battery at 100% SOC in each charge and discharge cycle can be calculated by the open circuit voltage value of 8 single batteries at 100% SOC and the average open circuit voltage value of 100% SOC of 8 series-connected single batteries in each charge and discharge cycle; the calculating method of the dispersion is that the difference between the open-circuit voltage value of the single battery at the 0% SOC point or the 100% SOC point and the average value of the open-circuit voltages of all the single batteries at the 0% SOC point or the 100% SOC point is divided by the average value of the open-circuit voltages of all the single batteries at the 0% SOC point or the 100% SOC point.
Fig. 5 to 7 are graphs showing the results of correlation analysis of the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, and the 0% SOC point open-circuit voltage dispersion of the single battery (No. 8 battery) having the maximum dispersion with respect to the capacity at different charge and discharge cycle times for the 1# series battery pack, respectively, and fig. 8 and 9 are graphs showing the results of correlation analysis of the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, and the 0% SOC point open-circuit voltage dispersion with respect to the capacity at different charge and discharge cycle times for the 1# series battery pack, respectivelyThe results of the correlation analysis between the difference and the discharge cut-off voltage range and the capacity are shown in the graph, and it can be seen from the analysis results of fig. 5 to 9 that the maximum charge cut-off voltage dispersion and the charge cut-off voltage range have strong linear correlation with the capacity of the battery pack, and the linear correlation coefficient R20.9868 and 0.9996, respectively, therefore, the maximum charge cut-off voltage dispersion and the relationship between the charge cut-off voltage range and the battery pack capacity can be used for judging the residual capacity of the lithium battery energy storage unit to be tested.
Remarking: since the dispersion of the open-circuit voltage at the 100% SOC point is not always the same single battery at different cycle times, the correlation between the dispersion and the capacity is not considered.
Example 2
The embodiment provides a state diagnosis method for utilizing a ternary lithium battery energy storage unit in a gradient manner, which comprises the following steps:
(1) the method comprises the following steps of carrying out cyclic charge and discharge on a ternary lithium battery energy storage unit (2# battery pack) which contains 8 series-connected single batteries in a gradient manner, wherein the charge and discharge method comprises the following steps: discharging the residual electricity of the battery at room temperature (20 +/-5 ℃), standing for 15 minutes, performing constant current charging at 0.3 ℃ until the voltage is reduced to 4.2V, converting the constant current charging into constant voltage charging until the charging current is reduced to 0.05C, standing for 30 minutes, and then performing constant current discharging at 0.5C until the voltage is reduced to 3.0V;
fig. 10-12 are graphs showing the correlation analysis results of the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the 0% SOC point open-circuit voltage and the capacity of the single battery with the maximum dispersion under different charge and discharge cycle times of the 2# series battery pack, respectively, fig. 13 and 14 are graphs showing the correlation analysis results of the charge cut-off voltage range and the discharge cut-off voltage range and the capacity under different charge and discharge cycle times, respectively, and it can be seen from the analysis results of fig. 10-14 that the linear correlation between the maximum charge cut-off voltage dispersion and the charge cut-off voltage range and the battery pack capacity is strong, and the linear correlation coefficient R is strong20.9978 and 0.9992, respectively, and thus can be used to compare the maximum charge cut-off voltage dispersion and the charge cut-off voltage spread with the battery packAnd judging the residual capacity of the energy storage unit of the lithium battery to be tested according to the relation between the capacities.
Remarking: since the dispersion of the open-circuit voltage at the 100% SOC point is not always the same single battery at different cycle times, the correlation between the dispersion and the capacity is not considered.
Example 3
The embodiment provides a diagnosis device for utilizing a lithium battery energy storage unit in a gradient manner, which comprises:
the dispersion and cut-off voltage range acquiring unit is used for acquiring the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at a 100% SOC point and the open-circuit voltage dispersion at a 0% SOC point of a single battery in the lithium battery energy storage unit to be tested under different charge and discharge cycle times, and the charge cut-off voltage range and the discharge cut-off voltage range of the lithium battery energy storage unit to be tested under different charge and discharge cycle times;
the lithium battery energy storage unit capacity characterization index acquisition unit acquires a characterization index with high correlation with the capacity of the lithium battery energy storage unit to be detected through correlation analysis of charge cut-off voltage dispersion, discharge cut-off voltage dispersion, open-circuit voltage dispersion at a 100% SOC point and open-circuit voltage dispersion at a 0% SOC point of the same single battery and the residual capacity of the lithium battery energy storage unit to be detected;
and the battery pack residual capacity acquisition unit is used for judging the residual capacity of the lithium battery energy storage unit to be tested according to the relation between the characterization index with high capacity relevance with the lithium battery energy storage unit to be tested and the capacity.
In light of the foregoing description of the preferred embodiments according to the present application, it is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention. The technical scope of the present application is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims (10)

1.A state diagnosis method for utilizing a lithium battery energy storage unit in a gradient manner is characterized by comprising the following steps:
the method comprises the steps of carrying out cyclic charging and discharging on a lithium battery energy storage unit to be detected, calculating the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at a 100% SOC point and the open-circuit voltage dispersion at a 0% SOC point of each single battery in the lithium battery energy storage unit under different cycle times, then respectively carrying out correlation analysis on the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at the 100% SOC point and the open-circuit voltage dispersion at the 0% SOC point of the same single battery under different cycle times and the residual capacity of the lithium battery energy storage unit to be detected under corresponding cycle times, respectively carrying out correlation analysis on the charge cut-off voltage range and the discharge cut-off voltage range of the lithium battery energy storage unit to be detected under different cycle times and the residual capacity of the lithium battery energy storage unit to be detected under corresponding cycle times, and screening out a characterization, and judging the residual capacity of the lithium battery energy storage unit to be tested according to the relation between the characterization index and the capacity.
2. The method for diagnosing the state of the lithium battery energy storage unit in the echelon utilization manner as claimed in claim 1, wherein the dispersion of the charge cut-off voltage, the dispersion of the discharge cut-off voltage, the dispersion of the open-circuit voltage at the 100% SOC point, and the dispersion of the open-circuit voltage at the 0% SOC point of the same single battery subjected to the correlation analysis with the remaining capacity of the lithium battery energy storage unit to be measured at the corresponding cycle number are the maximum dispersion of the charge cut-off voltage, the maximum dispersion of the discharge cut-off voltage, the dispersion of the open-circuit voltage at the maximum 100% SOC point, and the dispersion of the open-circuit voltage at the maximum 0% SOC point, respectively.
3. The method for diagnosing the state of the energy storage unit of the lithium battery by echelon utilization according to claim 1 or 2, wherein the characterization index having high correlation with the capacity of the energy storage unit of the lithium battery to be tested is a maximum charge cut-off voltage dispersion or a charge cut-off voltage range.
4. The method for diagnosing the state of the energy storage unit of the lithium battery by echelon utilization according to claim 1 or 2, wherein the correlation analysis is linear correlation coefficient analysis, and the high correlation is high linear correlation coefficient.
5. The method for diagnosing the state of the energy storage unit of the gradient lithium battery as claimed in claim 1 or 2, wherein the lithium battery is a lithium iron phosphate battery or a ternary lithium iron battery.
6. The method for diagnosing the state of the energy storage unit of the lithium battery used in the echelon manner according to claim 1 or 2, wherein the method for cyclically charging and discharging comprises: and discharging the residual electric quantity of the lithium battery energy storage unit to be tested, carrying out constant current charging to the lithium battery energy storage unit after the electric quantity is discharged to reach the upper limit voltage, then carrying out constant voltage charging until the current is reduced to be lower than the lower limit current, standing, and then stopping discharging when the current is discharged to reach the lower limit voltage by adopting a constant current discharging mode.
7. The method for diagnosing the state of an energy storage unit using lithium batteries in a stepwise manner according to claim 6, wherein the upper limit voltage is 3.6 to 4.2V and the lower limit voltage is 2.8 to 3.0V.
8. The method for diagnosing the state of the energy storage unit of the lithium battery used in the echelon form according to claim 6, wherein the current for constant current charging is 0.2 to 0.4C, the lower limit current is 0.05C, and the current for constant current discharging is 0.4 to 0.6C.
9. The method for diagnosing the state of the energy storage unit of the lithium battery used in the echelon according to claim 6, wherein the rest time after the residual electric quantity of the energy storage unit of the lithium battery to be tested is 10 to 20 minutes after the discharge is finished, and the rest time after the charge is 20 to 40 minutes.
10. A diagnosis device for gradedly utilizing a lithium battery energy storage unit is characterized by comprising:
the dispersion and cut-off voltage range acquiring unit is used for acquiring the charge cut-off voltage dispersion, the discharge cut-off voltage dispersion, the open-circuit voltage dispersion at a 100% SOC point and the open-circuit voltage dispersion at a 0% SOC point of a single battery in the lithium battery energy storage unit to be tested under different charge and discharge cycle times, and the charge cut-off voltage range and the discharge cut-off voltage range of the lithium battery energy storage unit to be tested under different charge and discharge cycle times;
the lithium battery energy storage unit capacity characterization index acquisition unit acquires a characterization index with high correlation with the capacity of the lithium battery energy storage unit to be detected through correlation analysis of charge cut-off voltage dispersion, discharge cut-off voltage dispersion, open-circuit voltage dispersion at a 100% SOC point and open-circuit voltage dispersion at a 0% SOC point of the same single battery and the residual capacity of the lithium battery energy storage unit to be detected;
and the battery pack residual capacity acquisition unit is used for judging the residual capacity of the lithium battery energy storage unit to be tested according to the relation between the characterization index with high capacity relevance with the lithium battery energy storage unit to be tested and the capacity.
CN201911420047.2A 2019-12-31 2019-12-31 State diagnosis method and device for echelon utilization of lithium battery energy storage unit Pending CN110988699A (en)

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Cited By (2)

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CN111600354A (en) * 2020-06-03 2020-08-28 桑顿新能源科技(长沙)有限公司 Grouping protection system for batteries used in echelon and battery pack forming method
CN112147528A (en) * 2020-09-24 2020-12-29 上海空间电源研究所 Method for diagnosing health state of lithium ion storage battery

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