JP2015010962A - Method for determining degradation of storage battery and device for determining degradation of storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for determining the degradation of a storage battery and a device for determining the degradation of the storage battery capable of improving the accuracy of determining the degradation of the storage battery for cyclical use.SOLUTION: The prevent invention comprises: a step S11 for fully charging a storage battery for cyclical use by equalized charging; a step S12 for discharging the storage battery to a 50-95% state of charge (SOC); a step S13 for measuring a voltage of the storage battery when charged with a current in the range 0.05-0.6 CA or discharged with a current in the range 0.05-1.0 CA; a step S14 for calculating, after calculating a polarization voltage ΔV from the measurement result, an internal DC resistance R from the calculated value; and a step S15 for determining a degradation state of the storage battery by comparing the internal DC resistance R, which is calculated from the polarization voltage on the basis of a data table indicating an internal DC resistance constituting a threshold J for the determination of degradation at charge time or at discharge time predetermined corresponding to a charge-time current (0.05-0.6 CA) or a discharge-time current (0.05-1.0 CA), and the internal DC resistance constituting the threshold J.

Description

  The present invention relates to a storage battery deterioration determination method and a storage battery deterioration determination apparatus for a cycle in which the state of charge is controlled within a predetermined range in order to operate in association with the power of a system power supply or the power from renewable energy.

An assembled battery system in which a plurality of storage batteries are connected in series and / or in parallel is used for industrial purposes, and is attached to a power supply facility such as communication or electric power so that the storage battery is fully charged by always performing float charging. It is used as an emergency power source by keeping the battery discharged during a power outage. In this case, a float lead storage battery or the like is used as the storage battery.
On the other hand, in recent years, it is used as a power storage power source that stores (charges) low-cost electricity at night in a storage battery, discharges (discharges) it when daytime power demand increases, and equalizes the power load. It has become to. In this case, a lead storage battery for cycles is used as the storage battery. In addition, an assembled battery system can be used in combination with wind power generation or solar power generation, which is a renewable energy, and discharges from the storage battery when the power generation amount is small, and charges the storage battery when the power generation amount is large. May also be used for leveling. Furthermore, it may be used in a hybrid manner in both the emergency and power storage applications.
Further, in the above-described storage battery for cycle, the state of the storage battery is changed to a partially charged state (PSOC: Partial) so that the cycle life is improved and the battery is easily charged in accordance with the output fluctuations of wind and sunlight with large fluctuations. (State of Charge) is increasingly used.
In this way, in a storage battery for a cycle, since the charge and discharge cycles are frequently repeated in the PSOC, the state of charge constantly fluctuates, and the deterioration state of the storage battery changes greatly depending on the usage situation, so the accurate deterioration determination of the storage battery Is particularly important.

  As a method for determining the deterioration of a storage battery, in the case of a float, the internal resistance is measured by the AC 4-terminal method using a fixed wiring internal resistance device during float charging, and this is compared with a threshold value to determine the deterioration. On the other hand, in the case of the cycle, the change in the discharge voltage is measured, and this is compared with the threshold value to determine the deterioration (degradation is larger than the threshold value). It has been proposed to do so (see, for example, Patent Document 1). In these determination methods, since the value changes depending on the state of charge (SOC) of the storage battery, measurement with an SOC with less error leads to accurate determination.

JP 2010-164441 A

  However, a cycle storage battery used for power storage or the like is subject to errors in current integration, charge / discharge device noise, etc., when the cycle of charging and discharging is repeated between a predetermined range of SOCs in PSOC. Since the SOC gradually shifts due to the influence, the deterioration cannot be determined with the correct SOC, so it is difficult to determine the deterioration with the high-accuracy correct SOC.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a storage battery deterioration determination method and a storage battery deterioration determination apparatus capable of improving the deterioration determination accuracy of a storage battery for a cycle. .

In order to solve the above-described problem, the storage battery deterioration determination method of the present invention is used for a battery pack system in which a plurality of storage batteries are connected in series and / or in parallel, and is used for a cycle operated in PSOC (partial charge state). A step of fully charging the storage battery by equal charge, a step of discharging to a predetermined SOC (charged state), a step of measuring a voltage when charged or discharged with a current in a range of 0.05 to 0.6 CA, and After calculating the polarization voltage from the measured voltage, the step of calculating the value of the DC internal resistance from the polarization voltage, and the direct current that becomes the threshold for deterioration determination at the time of charging or discharging that is predetermined corresponding to the current The deterioration determination of the storage battery is performed by comparing the DC internal resistance calculated from the polarization voltage based on the data table indicating the internal resistance with the DC internal resistance serving as the threshold. Characterized in that it comprises a degree, the.
According to this configuration, it is possible to improve the deterioration determination accuracy of the cycle storage battery.

The said structure WHEREIN: In the process discharged to the said predetermined | prescribed SOC, it discharges to 50 to 95% of SOC on the basis of the total electric discharge amount of the said storage battery before deterioration, It is characterized by the above-mentioned.
According to this configuration, by setting the SOC to 95% or less, it is possible to make a large polarization during charging of the assembled battery, making it difficult to reach the upper limit voltage during operation, and it is possible to correctly determine the deterioration state. . On the other hand, by setting the SOC to 50% or more, the time from full charge to adjustment can be shortened, and by not reducing the SOC too much, the life of the assembled battery can be prevented from decreasing.

Moreover, in the said structure, it is made to discharge to the middle SOC of the charging / discharging cycle in which the said storage battery is used in the process discharged to the said predetermined SOC.
According to this configuration, it is possible to determine the deterioration of the assembled battery 11 within the range of the SOC that is in operation, and it is possible to more appropriately determine the deterioration.

Moreover, the said structure WHEREIN: The said storage battery is operate | moved by PSOC of SOC 50 to 95% of range.
According to this configuration, the deterioration of the assembled battery can be more appropriately determined while preventing rapid deterioration of the assembled battery life. Further, by operating within this range, charging from other power can be performed efficiently.

In addition, the storage battery deterioration determination device of the present invention is used in an assembled battery system in which a plurality of storage batteries are connected in series and / or in parallel, and performs charge / discharge of a storage battery for a cycle operated in a PSOC (partial charge state). The storage battery is discharged to a predetermined SOC (charged state) by the charging / discharging unit and the charging / discharging unit, and then charged with a current in the range of 0.05 to 0.6 CA, or in the range of 0.05 to 1.0 CA. After measuring the voltage at the time of discharging with the current, and calculating the polarization voltage from the measured voltage, the DC internal resistance is calculated from the polarization voltage, and at the time of charging or discharging predetermined corresponding to the current The storage battery is compared by comparing the DC internal resistance calculated from the polarization voltage with the DC internal resistance serving as the threshold based on a data table indicating the DC internal resistance serving as a threshold for determining deterioration of the battery. Characterized in that it comprises an information processing unit for performing the deterioration determination.
According to this configuration, it is possible to improve the deterioration determination accuracy of the storage battery.

  ADVANTAGE OF THE INVENTION According to this invention, the deterioration determination precision of the storage battery for cycles can be improved.

It is a figure which shows the deterioration determination apparatus of the storage battery which concerns on embodiment of this invention. It is a graph which shows the relationship between the electric current and voltage of the discharge for 5 seconds in SOC90%. It is a graph which shows the relationship between the electric current of the 5th charge in SOC 90%, and a voltage. It is a flowchart which shows operation | movement of the deterioration determination apparatus of a storage battery.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a storage battery deterioration determination device according to an embodiment of the present invention.
The storage battery deterioration determination device (hereinafter referred to as a battery deterioration determination device) 10 is a device that determines the deterioration of an assembled battery 11 serving as a power source for a device that operates on electric power.
First, an example in which a lead storage battery is used as a storage battery constituting the assembled battery will be described as an example of the assembled battery 11 targeted by the battery deterioration determination device 10.
This assembled battery 11 is a lead acid battery for a cycle in which a plurality of cells (lead acid batteries) 12 are connected in series. In other words, the assembled battery 11 is intended to be used in a situation where the state of charge constantly fluctuates in order to repeat the charge and discharge cycles, so that the cycle life is extended, and the PSOC (Partial State; of Charge), which is a secondary battery designed to improve charge acceptance.
Specifically, the assembled battery 11 is used as a leveling power source that charges surplus power from, for example, wind power generation or solar power generation, which is renewable energy, and discharges insufficient power, or power at night It is used for power storage power sources for leveling the power load.

The battery deterioration determination device 10 includes a charge / discharge device (charge / discharge unit) 21 having a function of charging or discharging the assembled battery 11, a control function of the charge / discharge device 21, and an information processing having a deterioration determination function of the assembled battery 11. And an apparatus (information processing unit) 22.
The information processing apparatus 22 includes a measurement unit 24 that can measure the voltage and current of each cell 12 via a monitor line 23 connected to each cell 12 of the assembled battery 11, and a processing unit that inputs measurement results of the measurement unit 24. 25. Under the control of the processing unit 25, measurement by the measurement unit 24 and charging and discharging by the charge / discharge device 21 are controlled, and determination data is calculated based on the measurement data.

The processing unit 25 includes a storage unit 26 that stores various types of data. In the storage unit 26, program data for performing various controls and calculations for determining deterioration of the assembled battery 11, and deterioration determination Data such as the threshold value J is stored.
The threshold value J of the deterioration determination is a threshold value of the DC internal resistance R calculated from the polarization voltage ΔV, and these threshold values are set at a predetermined current rate of 0.05 to 1 CA, for example, every 0.05 CA increment. These are stored as a data table indicating the DC internal resistance R that is a threshold value for determining deterioration during charging or discharging.

FIG. 2 shows that a 2V-1000 Ah (10 hour rate capacity) cycle lead-acid battery is fully charged by equal charge, then discharged for 1 hour at a current of 0.1 CA, and the SOC is adjusted to 90%. It is the graph which plotted the electric current and voltage when discharging for 5 second by the electric current of 0.05CA (50A)-1CA (1000A). Here, the slope of the current and voltage indicates the DC internal resistance. From this graph, it can be seen that the relationship between the current and voltage is a straight line during discharge, and the DC internal resistance shows the same numerical value at any current. In addition, although the case where it discharged after adjustment to SOC90% was shown here, even when it discharged after adjustment to SOC50% -95%, the same behavior was shown.
On the other hand, FIG. 3 is a graph plotting current and voltage when a lead acid battery for a cycle with SOC adjusted to 90% is charged with a current of 0.05 CA (50 A) to 1 CA (1000 A) for 5 seconds. From this graph, during charging, the direct current internal resistance is the same because it shows linearity from 0.05CA (50A) to 0.6CA (600A), but the polarization increases when it exceeds 0.75CA (750A). I understand. Therefore, if the current rate during charging exceeds 0.75 CA, the DC internal resistance cannot be measured correctly due to the influence of oxygen overvoltage and hydrogen overvoltage, so the range of 0.05 CA to 0.6 CA is preferable. In addition, although the case where it charged after adjustment to SOC90% was shown here, even when it charged after adjustment to SOC50% -95%, the same behavior was shown.
Further, the DC internal resistance can be measured even when the current is less than 0.05 CA, both at the time of discharging and at the time of charging. However, since the polarization is relatively small and the measurement accuracy of the DC internal resistance is lowered, it may be 0.05 CA or more. preferable.
By using this data table format, it is possible to perform the deterioration determination more easily by comparing the calculated value and the data table value.

  The charge / discharge device 21 performs equal charge (including recovery charge and refresh charge) on the assembled battery 11 to eliminate the variation in SOC for each cell 12 under the control of the information processing device (information processing unit) 22. The assembled battery 11 is discharged or charged with a current value based on an instruction from the information processing device 22. As this charging / discharging device 21, a known charging / discharging device can be applied.

Next, operation | movement of this battery deterioration determination apparatus 10 is demonstrated.
FIG. 4 is a flowchart showing the operation of the battery deterioration determination device 10.
As shown in FIG. 4, in the battery deterioration determination device 10, first, the processing unit 25 of the information processing device 22 performs equal charge by the charge / discharge device 21 according to a predetermined schedule to fully charge the assembled battery 11. (Step S11: Charging step).
Next, the process part 25 discharges the assembled battery 11 by the charging / discharging apparatus 21 (step S12: discharge process). In this case, the processing unit 25 calculates the discharge amount by integrating the current values measured by the measurement unit 24, and monitors the discharge amount to determine the SOC (charge state) of the assembled battery 11 to the target value Sx. Adjust to.

Next, the processing unit 25 causes the charging / discharging device 21 to discharge or charge the assembled battery 11 whose SOC is adjusted to the target value Sx in step S12, and measures the voltage at this time by the measuring unit 24 ( Step S13: Voltage measurement step).
Subsequently, the processing unit 25 obtains the polarization voltage ΔV from the measurement result of this voltage, calculates the direct current internal resistance R from this value (step S14), and determines the deterioration state of the assembled battery 11 based on the direct current internal resistance R. Determination (step S15: determination process). The above is the deterioration determination process by the battery deterioration determination apparatus 10.

In general, when a lead-acid battery continues to be used in the PSOC state, sulfation of the negative electrode proceeds and the life tends to be short.
In this structure, since equal charge is performed according to a predetermined schedule, the assembled battery 11 composed of a lead storage battery is regularly charged equally. For this reason, the lead sulfate produced | generated on the negative electrode plate surface of each cell 12 at one end can be returned to sponge-like metal lead. Therefore, the progress of sulfation is suppressed, the SOC is returned to 100%, and the SOC error generated during operation is easily reset.
Moreover, this equal charge can omit step S11 of the first equal charge of the deterioration determination by utilizing the timing of the equal charge performed periodically.

In step S12, the processing unit 25 sets the target value Sx to a value within the range of 50 to 95%.
Here, as an example, Table 1 shows the time until the SOC adjustment of a 2V-1000 Ah (10 hour rate capacity) cycle lead storage battery and the remaining capacity after the SOC adjustment.

According to the study by the inventors, when the SOC exceeds 95%, the lead storage battery is largely polarized when charged, so that it becomes easy to reach the upper limit voltage during operation as the assembled battery 11 and it is difficult to correctly determine the deterioration state. In addition, it is necessary for the battery pack 11 to be an SOC that can always be charged and discharged in order to stabilize the power. However, if the SOC of the lead storage battery exceeds 95%, the amount of charge accepted is too small, which is disadvantageous for power stabilization. I found out that
On the other hand, if the SOC is 40%, it takes too much time to adjust the lead storage battery from full charge to the target SOC, which is not preferable. In addition, an undegraded battery has a remaining capacity even if the SOC is 40%, so there is no problem with charging and discharging. However, in a battery deteriorated to a capacity of 70% of the initial capacity, the remaining capacity becomes 100 Ah when the SOC is 40%. If the battery is charged / discharged, the battery will be deeply discharged, and the deterioration determination may cause damage to the lead storage battery, leading to a decrease in the life of the assembled battery 11. Furthermore, there is a drawback that the amount of power that can be discharged in an emergency is reduced.

The adjustment to the target value Sx in step S12 will be described. In the present embodiment, the total discharge electricity amount of the assembled battery 11 before deterioration is used as a reference (SOC = 100%), and a value obtained by subtracting the discharge amount from this total discharge electricity amount is regarded as the current SOC, and this SOC is the target. Discharge until value Sx.
Here, when the deterioration of the assembled battery 11 has not progressed, the actual SOC can be adjusted to substantially the target value Sx by the adjustment method described above.
On the other hand, when the deterioration of the assembled battery 11 is progressing, the actual SOC does not reach 100% even when the batteries are evenly charged, so that a deviation occurs between the measured SOC and the actual SOC. For example, if the target value Sx is set to 40%, the actual SOC will be lower than that.
In the present configuration, as described above, the target value Sx is set to 50% or more, so that even if a deviation occurs from the actual SOC, it is possible to avoid that the actual SOC becomes considerably low. it can. Therefore, a decrease in battery life can be suppressed.

About target value Sx, More preferably, in the range of 50 to 95%, the middle SOC of the charge / discharge cycle in which this assembled battery 11 is used is good. For example, when the assembled battery 11 is operated with an SOC of 50 to 95%, the target value Sx is preferably set to 72.5%, which is an intermediate value of 50 to 95%. If it does in this way, degradation of assembled battery 11 can be judged with SOC currently used in operation, and degradation can be judged more appropriately.
Here, the value of the target value Sx may be stored in advance in the storage unit 26 of the information processing device 22. Alternatively, the information processing device 22 may monitor the SOC, periodically obtain the SOC in the middle of the charge / discharge cycle based on the monitoring result, and set it to the target value Sx.

  As mentioned above, it is preferable that the lead acid battery 12 which comprises the assembled battery 11 is operated by PSOC of SOC 50 to 95% of range. This is because if the SOC is less than 50%, the performance deterioration of the lead storage battery 12 becomes remarkable, and if the SOC is more than 95%, the charging efficiency from other electric power becomes worse.

In step S13, the processing unit 25 sets the current with respect to the rated discharge capacity as the target current value Ix to a value within the range of 0.05 to 1.0 CA during discharge. Moreover, it sets to the value within the range of 0.05-0.6CA at the time of charge.
According to the study by the inventors, if it is less than 0.05 CA, the determination may be difficult because the polarization when the assembled battery 11 is charged or discharged is small. In addition, it is more than 1.0 CA during discharge, and the polarization at the time of discharge is large, so that it is easy to reach the lower limit voltage during operation. This makes it easier to reach the correct judgment.

Subsequently, the step of calculating the DC internal resistance R in step S14 will be described.
After obtaining the polarization voltage ΔV in step S13, the processing unit 25 calculates the DC internal resistance R from the polarization voltage ΔV by the following equation (1).
R = ΔV / Ix (1)

Subsequently, in step S <b> 15, the processing unit 25 determines the life state of the assembled battery 11 by comparing the DC internal resistance R with the deterioration determination threshold value J stored in the storage unit 26.
For example, if the DC internal resistance R is equal to or greater than the threshold value J (resistance value), it is determined that the assembled battery 11 has reached the end of its life. For this deterioration determination, a well-known method for determining deterioration based on the polarization voltage ΔV or the DC internal resistance R can be widely applied.

  As described above, in the present embodiment, after the assembled battery 11 composed of the lead acid battery 12 for cycle is fully charged by equal charge, the step of discharging to 50 to 95% SOC; 0.05 A step of measuring a voltage when charged with a current in a range of .about.0.6 CA or discharged with a current in a range of 0.05 to 1.0 CA, and after calculating a polarization voltage .DELTA.V from the measured voltage, Based on the step of calculating the direct current internal resistance R from the voltage ΔV and the data table showing the direct current internal resistance that becomes the threshold value J of the deterioration determination at the time of charging or discharging corresponding to the current, the polarization A step of determining the deterioration of the battery pack 11 (lead battery 12 for cycle) by comparing the DC internal resistance R calculated from the voltage and the DC internal resistance that is the threshold value J.

According to this configuration, as described above, the SOC is returned to 100%, the SOC error generated during operation is reset, and the deterioration state is easily determined within a range that does not reach the upper limit voltage during operation. Moreover, it becomes easy to avoid that it takes too much time to adjust from full charge and that the SOC is lowered too much to shorten the battery life.
Accordingly, in this configuration, it is possible to improve the deterioration determination accuracy of the assembled battery 11 including the lead storage battery 12 for cycles.
Therefore, it is possible to maintain a highly reliable assembled battery system when used for power storage applications such as power load leveling and leveling of renewable energy such as solar power generation.

Furthermore, in this configuration, in the discharge after the full charge is performed by the equal charge, the SOC is discharged to 50 to 95% based on the total discharge electricity amount of the assembled battery 11 before deterioration, so that the SOC can be easily adjusted. . Further, even if a deviation occurs between the adjusted SOC and the actual SOC, it is possible to suppress the actual SOC from being adjusted too low.
Further, in this configuration, in the discharge after the full charge is performed by the equal charge, the battery is discharged to the middle SOC of the charge / discharge cycle in which the assembled battery 11 is used, so that the deterioration can be more appropriately determined.

  The above-described embodiment is merely an aspect of the present invention, and can be arbitrarily modified and applied without departing from the gist of the present invention. For example, in the above-described embodiment, the case where the present invention is applied to the deterioration determination method for the assembled battery 11 or the battery deterioration determination apparatus 10 has been described, but the present invention is not limited thereto. The present invention can be widely applied to a deterioration determination method and a deterioration determination apparatus for a nickel-hydrogen storage battery for a cycle having a plurality of cells.

10 Storage battery deterioration determination device (Battery deterioration determination device)
11 assembled battery 12 cell, storage battery, lead storage battery 21 charge / discharge device (charge / discharge unit)
22 Information processing device (Information processing unit)
23 Monitor Line 24 Measuring Unit 25 Processing Unit 26 Storage Unit

Claims (5)

  A process for charging a storage battery for a cycle that is used in an assembled battery system in which a plurality of storage batteries are connected in series and / or in parallel and operated in PSOC (partial charge state) by equal charge, and a predetermined SOC (charge state) ), A step of measuring a voltage when charged with a current in a range of 0.05 to 0.6 CA, or a discharge with a current of a range of 0.05 to 1.0 CA, and from the measured voltage After calculating the polarization voltage, a step of calculating a DC internal resistance from the polarization voltage, and a data table showing a DC internal resistance that becomes a threshold value for deterioration determination at the time of charge or discharge determined in advance corresponding to the current And determining the deterioration of the storage battery by comparing the direct-current internal resistance calculated from the polarization voltage with the direct-current internal resistance serving as the threshold value. Deterioration determination method of the storage battery to be.   2. The method for determining deterioration of a storage battery according to claim 1, wherein in the step of discharging to the predetermined SOC, the battery is discharged to 50 to 95% of SOC based on a total discharge electricity amount of the storage battery before deterioration.   The method for determining deterioration of a storage battery according to claim 1 or 2, wherein, in the step of discharging to the predetermined SOC, the battery is discharged to an intermediate SOC of a charge / discharge cycle in which the storage battery is used.   The storage battery deterioration determination method according to any one of claims 1 to 3, wherein the storage battery is operated with a PSOC in a range of SOC 50 to 95%. A charge / discharge unit that charges and discharges a storage battery for a cycle that is used in an assembled battery system in which a plurality of storage batteries are connected in series and / or in parallel, and is operated in a PSOC (partial charge state);
The storage battery is discharged to a predetermined SOC (charged state) by the charging / discharging unit, and then charged with a current in the range of 0.05 to 0.6 CA or discharged with a current in the range of 0.05 to 1.0 CA. After measuring the voltage at this time, calculating the polarization voltage from this measurement voltage, calculating the DC internal resistance from the polarization voltage, and a threshold value for deterioration determination at the time of charging or discharging that is predetermined corresponding to the current An information processing unit that determines deterioration of the storage battery by comparing the DC internal resistance calculated from the polarization voltage based on the data table indicating the DC internal resistance to be compared with the DC internal resistance that is the threshold value. An apparatus for determining deterioration of a storage battery.

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