JP5809934B2 - Power storage device and power supply system - Google Patents

Description

  The present invention relates to a power storage device, and particularly to a technique for reducing deterioration (aging deterioration) due to storage of a storage battery included in the power storage device. The present invention also relates to a power supply system including such a power storage device.

  For deterioration of storage batteries (secondary batteries) such as lithium ion batteries and nickel metal hydride batteries, in addition to deterioration at the time of charge / discharge (cycle deterioration), aged deterioration even when not being charged / discharged (preservation deterioration) (See, for example, Patent Document 1). A power storage device including a storage battery may be used as an uninterruptible power supply (UPS), for example, and may be stored for a long time without being charged / discharged. It is important with the reduction of cycle degradation.

  Patent Document 2 discloses a technique related to extending the life of a storage battery. Patent Document 2 discloses a storage battery discharge control device for extending the life of a storage battery, and the control means provided in this device is a standard that guarantees the life of a storage battery based on the depth of discharge detected by the discharge depth detection means. The operation of the power-supplied device is controlled so as not to exceed the depth of discharge. Thereby, in the said discharge control apparatus, the influence on the lifetime of a storage battery by overdischarge can be eliminated. As can be seen from the above, Patent Document 2 does not disclose a technique for reducing the aging of the storage battery.

JP 2003-17138 A Japanese Patent Laid-Open No. 10-243572

  In view of the above points, an object of the present invention is to provide a power storage device that can reduce aged deterioration (storage deterioration) of a storage battery. Another object of the present invention is to provide a power supply system including such a power storage device.

  In order to achieve the above object, a power storage device according to the present invention is a power storage device including a plurality of storage batteries connected in parallel and an adjustment unit provided to adjust the SOC of each of the plurality of storage batteries. When the total remaining capacity of the storage batteries is stored as a predetermined value, the SOCs of the plurality of storage batteries are configured to be divided into a plurality of types without being the same (first configuration).

  In the first configuration, the storage battery may be a single storage battery cell, or may be a battery (assembled battery) configured by a plurality of storage battery cells.

  The present applicant has found through experiments that there is a storage battery that exhibits nonlinear characteristics with respect to a change in the degree of deterioration of the storage battery (the degree of aging deterioration) with respect to a change in the stored SOC (SOC at the start of storage). For this reason, as in this configuration, when storing the storage battery under certain conditions, the SOCs of the plurality of storage batteries are not all the same, but are divided into a plurality of types, compared with the case where all the SOCs are made identical. It becomes possible to reduce the average deterioration degree (degree of aging deterioration) of the plurality of storage batteries.

  In the power storage device having the first configuration, the SOC of each of the plurality of storage batteries is deterioration information indicating a relationship between the SOC at the start of storage of the storage battery and the deterioration degree after the storage battery is stored for a predetermined period. It is preferable that the configuration is determined based on the second configuration. In the power storage device of the second configuration, when the average deterioration degree of the plurality of storage batteries assumed from the SOC of each of the plurality of storage batteries and the deterioration information is the same for all the SOCs of the plurality of storage batteries Preferably, the SOC of each of the plurality of storage batteries is determined (third configuration) so as to be lower than the average degree of deterioration of the plurality of storage batteries assumed from the deterioration information.

  In the power storage device having any one of the first to third configurations, when the total remaining capacity of the plurality of storage batteries is stored so as to have a predetermined value, the allocation of the SOC to the plurality of storage batteries is performed at a predetermined timing. It is good also as a structure replaced with (4th structure). According to this configuration, it is possible to make the deterioration progress (progress of aging deterioration) of each of the plurality of storage batteries equal.

  In the power storage device having any one of the first to fourth configurations, even when the plurality of storage batteries are charged and discharged, the SOCs of the plurality of storage batteries are not all the same, but are divided into a plurality of types. It is good also as a structure (5th structure). In a storage battery included in a power storage device, aging progresses not only during storage but also during charging and discharging. For this reason, according to this structure, reduction of aged deterioration of the some storage battery with which an electrical storage apparatus is provided can be performed more effectively.

  In the power storage device having any one of the first to fifth configurations, the adjustment unit includes a plurality of DC-DC converters and a control unit that controls the plurality of DC-DC converters (first configuration). 6) may be employed. According to this configuration, since a plurality of power storage devices having different SOCs can be used simultaneously, the output power of the power storage device can be sufficiently secured. In some cases, a switch may be used instead of the DC-DC converter.

  In order to achieve the above object, a power supply system of the present invention is provided with a power supply source capable of supplying power to an external load, and capable of charging power from the power supply source, and discharging to the external load. A configuration (seventh configuration) provided with any one of the first to sixth power storage devices provided as possible.

  In this configuration, the power supply system is configured using a power storage device that can reduce the aging deterioration of the storage battery, and it is expected to extend the life of the power supply system.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage apparatus which can reduce aged deterioration (storage deterioration) of a storage battery can be provided. In addition, according to the present invention, the life of the power supply system can be expected to be extended.

The block diagram which shows schematic structure of the power supply system which concerns on 1st Embodiment of this invention. The flowchart which shows the flow of the aged deterioration reduction control process of the storage battery performed with the electrical storage apparatus of 1st Embodiment. The graph which shows an example of the aged deterioration characteristic of the storage battery with which the electrical storage apparatus of 1st Embodiment is equipped The graph which shows another example of the aged deterioration characteristic of the storage battery with which the electrical storage apparatus of 1st Embodiment is equipped. In the electrical storage apparatus of 1st Embodiment, it is a figure for demonstrating the determination method of SOC of each storage battery at the time of a preservation | save, The figure at the time of making SOC of all the storage batteries the same (comparative figure) In the electrical storage apparatus of 1st Embodiment, it is a figure for demonstrating the determination method of SOC of each storage battery at the time of a preservation | save, and the figure when SOC of each storage battery is divided into multiple types The figure for demonstrating the modification of the aged deterioration reduction control process of the storage battery in 1st Embodiment. The block diagram which shows the modification of the electrical storage apparatus of 1st Embodiment. The block diagram which shows schematic structure of the power supply system which concerns on 2nd Embodiment of this invention. The graph for demonstrating the usage method of the electrical storage apparatus of 2nd Embodiment. The graph which shows the change (an example) of SOC of each storage battery with which the electrical storage apparatus of 2nd Embodiment is equipped. The figure for demonstrating the modification of the aged deterioration reduction control process of the storage battery in 2nd Embodiment.

  Hereinafter, embodiments of a power storage device and a power supply system of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a block diagram showing a schematic configuration of a power supply system 1 according to the first embodiment of the present invention. In FIG. 1, thick lines indicate power lines and thin lines indicate signal lines. As shown in FIG. 1, the power supply system 1 includes a power supply source 10, a PCS (Power Conditioning System) 20, and a power storage device 30.

  The power supply source 10 supplies power to the external load and the power storage device 30. In the present embodiment, a commercial AC power supply (connected to the power system) is assumed as the power supply source 10. However, the power supply source may be a natural energy power generation device that generates power using natural energy. Examples of the natural energy power generation device include a solar power generation device that generates power using sunlight and a wind power generation device that generates power using wind power.

  The PCS 20 (power conversion unit) includes a bidirectional converter. With this bidirectional converter, the PCS 20 converts AC power from the power supply source 10 into DC power, and also converts DC power from the power storage device 30 into AC power. Note that, for example, when a solar power generation device is employed as the power supply source, since the supplied power is a direct current, the type of power converter provided in the PCS needs to be changed as appropriate.

  The power storage device 30 includes a controller 31, four DC-DC converters 32a to 32d, and four storage batteries 33a to 33d. The first DC-DC converter 32a is connected to the first storage battery 33a, the second DC-DC converter 32b is connected to the second storage battery 33b, the third DC-DC converter 32c is connected to the third storage battery 33c, and the fourth DC-DC converter 32d is connected to the fourth storage battery 33d. These four sets are connected in parallel.

  The storage batteries 33a to 33d may be appropriately selected from rechargeable batteries such as lithium ion batteries and nickel metal hydride batteries. Moreover, the storage batteries 33a to 33d may be configured by one storage battery cell, or may be an assembled battery in which a plurality of storage battery cells are connected in series, parallel, or series-parallel. Moreover, the four storage batteries 33a-33d have the same full charge capacity in the state which has not deteriorated.

  The controller 31 outputs a command signal related to charging / discharging of the storage batteries 33a to 33d connected to the DC-DC converters 32a to 32d to the DC-DC converters 32a to 32d. Each of the DC-DC converters 32a to 32d converts the electric power supplied from the PCS 20 into an appropriate electric power for each of the storage batteries 33a to 33d and outputs the electric power. Moreover, each DC-DC converter 32a-32d converts the electric power supplied from each storage battery 33a-33d into suitable electric power for PCS20, and outputs it. That is, control (battery capacity adjustment) related to charging / discharging of each of the storage batteries 33a to 33d is executed by the controller 31 and each of the DC-DC converters 32a to 32d.

  The controller 31 includes a non-volatile memory 31a in which data (described later) relating to the aging deterioration characteristics of the storage battery is stored. Further, battery information including SOC (State Of Charge) is transmitted to the controller 31 from each of the storage batteries 33a to 33d. The SOC is an index indicating the state of charge of the battery, and is represented by the ratio (percentage) of the dischargeable capacity (remaining capacity) to the full charge capacity. The SOC of each of the storage batteries 33a to 33d is obtained, for example, from the integrated value of the charge / discharge current flowing through each of the storage batteries 33a to 33d. Further, the SOC of each of the storage batteries 33a to 33d is obtained by referring to a calculation formula or table indicating a relationship between the SOC and the open circuit voltage (OCV) determined in advance of each of the storage batteries 33a to 33d. You can also.

  The four storage batteries 33a to 33d are an example of a plurality of storage batteries connected in parallel according to the present invention. The controller 31 and the four DC-DC converters 32a to 32d are examples of the adjusting means of the present invention.

  Next, a control method for reducing aging deterioration (also referred to as storage deterioration) of the storage battery, which is executed in the power storage device 30 configured as described above, will be described. The four storage batteries 33a to 33d of the power storage device 30 are stored so that the total remaining capacity becomes a predetermined value for the purpose of enabling power supply from the power storage device 30 to an external load, for example, during a power failure. The predetermined value is appropriately determined depending on the operation of the power supply system 1.

  FIG. 2 is a flowchart illustrating a flow of the storage battery aging deterioration control process executed by the power storage device 30 of the first embodiment. When the controller 31 determines that it is time to save the total remaining capacity of the four storage batteries 33a to 33d to a predetermined value (Yes in step S1), the storage battery is stored in the memory 31a over time. Data (deterioration information) relating to storage deterioration characteristics is read (step S2).

  Here, the deterioration information stored in the memory 31a will be described with reference to FIG. 3A. FIG. 3A is a graph illustrating an example of aged deterioration characteristics of the storage batteries 33a to 33d included in the power storage device 30 of the first embodiment. In FIG. 3A, the horizontal axis indicates the SOC of the storage battery at the start of storage, and the vertical axis indicates the ratio (percentage) of the full charge capacity before and after storing the storage battery for a predetermined period (in this example, 12 months). The vertical axis is an indicator of the degree of deterioration of the storage battery. When the vertical axis is 100%, the full charge capacity has not changed, so it has not deteriorated (degradation progress is zero). When the vertical axis is 90%, the full charge capacity has decreased due to storage. The capacity was degraded by 10%.

  As illustrated in FIG. 3A, the storage batteries 33a to 33d included in the power storage device 30 of the first embodiment have a degree of deterioration after being stored for a predetermined period as the SOC (storage SOC) at the start of storage increases. I understand. However, the change rate of the deterioration degree with respect to the change of the stored SOC changes at the boundary of the stored SOC of 50%. That is, it is recognized that the rate of change (increase rate) of the degree of deterioration with respect to the change in the stored SOC tends to be smaller when the stored SOC is smaller than 50% than when the stored SOC is larger than 50%. In the memory 31a, such deterioration characteristics of the storage battery are stored, for example, in the form of a table or a calculation formula.

  Returning to FIG. 2, the controller 31 that has read the deterioration information determines the SOC to be assigned to each of the storage batteries 33a to 33d (step S3). This determination is performed as follows. In this determination, as described above, it is assumed that the total remaining capacity of all the storage batteries 33a to 33d is a predetermined value.

For example, when two types of SOCs are assigned (SOCy and SOCz), the SOC is determined so as to satisfy the following expressions (1) and (2). Note that SOCx is an SOC value (a value obtained by dividing the total value of the remaining capacities of the above-described storage batteries by the number of storage batteries) when the SOCs of all the storage batteries are the same. Βx is a degree of deterioration (a value obtained from deterioration information) when the SOC of the storage battery is SOCx. Βy is the degree of deterioration when the SOC of the storage battery is SOCy. Βz is a degree of deterioration when the SOC of the storage battery is set to SOCz.
βx> (βy + βz) / 2 (1)
SOCx = (SOCy + SOCz) / 2 (2)

  Here, a case where SOCx = 50% will be described as an example. When the SOCs of the storage batteries 33a to 33d are all 50% (see FIG. 4A), the average deterioration degree of the four storage batteries 33a to 33d is the deterioration information read out earlier (corresponding to the graph of FIG. 3A). ). In the example of FIG. 3A, the degree of deterioration is 5% (βx = 5%). Next, based on the previously read deterioration information (corresponding to the graph of FIG. 3A) so that the average deterioration degree of the four storage batteries 33a to 33d is lower than the previously obtained deterioration degree (βx = 5%). Thus, the SOC of each of the storage batteries 33a to 33d is determined (sorted into a plurality of types).

  Here, it is preferable that the controller 31 allocates the SOC so that the number of storage batteries having the lower limit value of the SOC at the time of storage allowed by the power supply system 1 is as large as possible. The lower limit value of the SOC may be stored in advance in the memory 31a, or may be provided from a controller (not shown) of the power supply system 1.

  When the SOC allowed by the power supply system 1 is 25%, for example, as shown in FIG. 4B, the SOC of the first storage battery 33a and the second storage battery 33b is 25% (SOCy = 25%), the third storage battery 33c and the fourth storage battery 33c. The SOC of the storage battery 33d is preferably 75% (SOCz = 75%). In this case, the average deterioration degree of the four storage batteries 33a to 33d is 4% (= (2.5% × 2 + 5.5% × 2) / 4 = (βy + βz) / 2) (see FIG. 3). That is, the degree of deterioration (4%) is lower than the degree of deterioration (5%) when the SOCs of the four storage batteries 33a to 33d are all the same (satisfying equation (1)).

  If the lower limit value of the SOC allowed by the power supply system 1 is 0%, the SOCs of the first storage battery 33a and the second storage battery 33b are 0% (SOCy = 0%), the third storage battery 33c, and the fourth storage battery 33d. The SOC is preferably 100% (SOCz = 100%). In this case, the average deterioration degree of the four storage batteries 33a to 33d can be 3% (= (0% × 2 + 6% × 2) / 4) (below βx).

  When the controller 31 determines the SOC of each of the storage batteries 33a to 33d, the controller 31 charges or discharges each of the storage batteries 33a to 33d so that the determined SOC is obtained (step S4). The operation of setting each storage battery 33a to 33d to the determined SOC may be performed simultaneously on each storage battery 33a to 33d, or may be performed in a plurality of groups or individually. The storage is started when the SOC of each of the storage batteries 33a to 33d reaches the target SOC value (step S5). Thus, the storage battery aging deterioration control process ends.

  By performing the aging deterioration reduction control process as described above, the aging deterioration (storage deterioration) of the four storage batteries 33a to 33d can be reduced.

  In addition, the average deterioration degree of the four storage batteries 33a to 33d assumed from the SOC and the aging deterioration characteristics of the storage batteries 33a to 33d is assumed from the aging deterioration characteristics when the SOCs of the storage batteries 33a to 33d are all the same. What is necessary is that the SOC of each of the storage batteries 33a to 33d can be determined so as to be lower than the average deterioration degree of the four storage batteries 33a to 33d. For this reason, in addition to a storage battery (the characteristic shown in FIG. 3 is applicable) in which the increase rate of the deterioration degree is smaller on the side where the storage SOC is larger than the point where the change rate of the deterioration degree (the change ratio with respect to the change of the storage SOC) changes For example, a storage battery that changes in a direction in which the degree of deterioration is reduced (for example, a storage battery that shows a V-shaped graph with a storage SOC of 50% in FIG. 3 as a vertex) can be used as the storage battery of this embodiment.

  FIG. 3B is a graph illustrating another example of the aging deterioration characteristics of the storage batteries 33a to 33d included in the power storage device 30 of the first embodiment. The horizontal and vertical axes in FIG. 3B are the same as in FIG. 3A. FIG. 3B shows nonlinear characteristics as in FIG. 3A, but is more complicated. Generally speaking, when the stored SOC is about 0 to 25%, the degree of deterioration increases as the stored SOC increases (the rate of increase in the degree of deterioration with respect to changes in the stored SOC is relatively large). When the stored SOC is about 25 to 50%, the degree of deterioration does not change much (slightly increases) even if the stored SOC changes. Further, when the stored SOC is about 50% or more, the degree of deterioration increases as the stored SOC increases. However, the increase rate of the degree of deterioration with respect to the change in the stored SOC is not so large until the stored SOC is about 75%. When approaching 100%, the rate of increase in deterioration (relative to changes in stored SOC) becomes relatively large.

  Even when a storage battery having such characteristics is used, for example, the SOC of the first storage battery 33a and the second storage battery 33b is 10% (corresponding to SOCy in FIG. 3B), and the SOC of the third storage battery 33c and the fourth storage battery 33d. If the SOC allocation is determined so that is 60% (corresponding to SOCz in FIG. 3B), it is possible to reduce aging degradation. Here, it is assumed that SOCx = 35% in the above formula (2). As can be seen from FIG. 3B, when the SOCs of all the storage batteries 33a to 33d are the same, the deterioration degree is 5%, but by assigning the SOC as described above (SOCy = 10%, SOCz = 60%) The degree of deterioration is suppressed to 4.25% (= (3% × 2 + 5.5% × 2) / 4).

  The aged deterioration reduction control process described above may be performed every time when the storage batteries 33a to 33d are stored. However, once the SOC allocation of each of the storage batteries 33a to 33d is determined, thereafter, the SOC determination process (steps S2 and S3) is not performed, and each of the storage batteries 33a to 33d is set so as to obtain the previously determined SOC. Charging / discharging may be performed. Alternatively, the SOC of each of the storage batteries 33a to 33d at the time of storage may be determined in advance according to the method described in step S3, and the determined value may be stored in the memory 31a. In this case, the controller 31 performs only the process of reading out the SOC of each of the storage batteries 33a to 33d from the memory 31a at the time of storage, and does not perform the arithmetic process for determining the SOC distribution.

  Further, the deterioration information is not obtained in advance by experiments, but may be deterioration information obtained by operating the power storage device 30. For example, at first, the SOC determination process of each of the storage batteries 33a to 33d at the time of storage is performed using the deterioration information obtained in the experiment, and the SOC determination process is obtained by operation at a certain timing. A configuration in which the deterioration information is changed so as to be performed may be employed.

  Here, the modification regarding the structure of 1st Embodiment is demonstrated. FIG. 5 is a diagram for explaining a modification of the aging deterioration reduction control process of the storage battery in the first embodiment. In this modification, when the storage period elapses a predetermined period (which may be determined as appropriate), the SOC assignment at the time of storage of each of the storage batteries 33a to 33d is switched (rotated).

  In the example shown in FIG. 5, first, the SOC when the first storage battery 33a and the second storage battery 33b are stored is 25%, and the SOC when the third storage battery 33c and the fourth storage battery 33d are stored is 75%. When the storage period passes a predetermined period, the SOC when the first storage battery 33a and the second storage battery 33b are stored is 75%, and the SOC when the third storage battery 33c and the fourth storage battery 33d are stored is 25%. Is replaced. By performing such replacement, it can be expected that the progress of the deterioration degree of each of the storage batteries 33a to 33d becomes equal.

  FIG. 6 is a block diagram illustrating a modification of the power storage device 30 according to the first embodiment. In the modification shown in FIG. 6, the DC-DC converters 32a to 32d in the power storage device 30 of the first embodiment are replaced with switches 34a to 34d. Even with such a configuration, the same aging deterioration reducing process as described above can be executed.

  However, in the configuration of this modification, for example, when a power failure occurs during storage and the power storage device 30 is used, storage batteries having different SOCs cannot be used at the same time. For example, only the first storage battery 33a and the second storage battery 33b having a large SOC are used. For this reason, the maximum output power of the power storage device 30 is reduced. Even with such a configuration, for example, if the power demand of the external load is small when a power failure occurs, there is no problem at all.

  In the case of this configuration, the controller 31 (see FIG. 1) and the switches 31a to 31d controlled by the controller 31 correspond to the adjusting means of the present invention.

Second Embodiment
Next, the power supply system and power storage device of the second embodiment will be described. FIG. 7 is a block diagram showing a schematic configuration of the power supply system 2 according to the second embodiment of the present invention. As shown in FIG. 7, the power supply system 2 includes a solar power generation device 11 and a commercial AC power source (connected to a power system) 12, a PCS (power conversion unit) 21, and a power storage device 40 that are power supply sources. Prepare.

  The PCS 21 includes a DC-DC converter 21a and an inverter 21b. The DC-DC converter 21a provided in the PCS 21 converts the DC power supplied from the solar power generation device 11 into appropriate DC power. The DC power output from the DC-DC converter 21a is appropriately supplied to an external load (DC device), the inverter 21b, or the power storage device 40. The inverter 21b converts the DC power supplied from the solar power generation device 11 or the power storage device 30 into appropriate AC power. The AC power output from the inverter 21b is supplied to an external load (AC device) or supplied to the power system 12. In some cases, a bidirectional converter may be used instead of the inverter 21b.

  In addition, the electrical storage apparatus 40 is comprised with the same member as the electrical storage apparatus 30 of 1st Embodiment. For this reason, detailed description of the configuration is omitted. Moreover, the same member is demonstrated using the same code | symbol as 1st Embodiment.

  As a method of using the power storage device 40 in the power supply system 2, a method of use as shown in FIG. 8 is assumed. FIG. 8 is a graph for explaining a method of using the power storage device 40 of the second embodiment. In FIG. 8, the horizontal axis represents time (one day's time), and the vertical axis represents the average SOC of the four storage batteries 33a to 33d.

  In the example illustrated in FIG. 8, it is assumed that the power generated by the solar power generation device 11 covers most of the power required for the external load during the daytime. It is assumed that surplus power out of the power generated by the solar power generation device 1 is stored (charged) in the power storage device 40. In the example illustrated in FIG. 8, the power storage device 40 is discharged in the evening because the power storage device 40 supplies a part of the power that cannot be supplied by the solar power generation device 1. At night, since the solar power generation device 11 does not generate power, the power storage device 40 is not charged, and the power storage device 40 is adjusted so that the total remaining capacity of the four storage batteries 33a to 33d becomes a predetermined value. It is not used (saved) after that.

  In the example illustrated in FIG. 8, it is assumed that the total value of the remaining capacity when the SOC of each of the storage batteries 33a to 33d is 50% is equal to the predetermined value described above. The reason why the average SOC of the four storage batteries 33a to 33d is set to 50% at night is, for example, for the purpose of enabling the power storage device 40 to be used as a power failure countermeasure.

  FIG. 9 is a graph showing a change (one example) in SOC of each of the storage batteries 33a to 33d provided in the power storage device 40 of the second embodiment. In FIG. 9, the horizontal axis represents time (one day's time), and the vertical axis represents the SOC of each of the storage batteries 33a to 33d. In FIG. 9, (a) shows the SOC change of the first storage battery 33a and the second storage battery 33b, and (b) shows the SOC change of the third storage battery 33c and the fourth storage battery 33d. The broken line graph is an SOC change pattern in the case where the SOCs of the four storage batteries 33a to 33d are all the same, and are shown for comparison.

  As shown in FIG. 9, the SOC of the first storage battery 33a and the second storage battery 33b is 25%, the third storage battery 33c, and the fourth storage battery 33d at night (that is, the storage period in which the storage batteries 33a to 33d are stored). Is adjusted to be constant at 75% (the same as the state shown in FIG. 4B).

  For this reason, as described in the first embodiment, the average deterioration degree of the four storage batteries 33a to 33d during the storage period (aging deterioration) as compared with the case where the four storage batteries 33a to 33d are all arranged in the same SOC. Deterioration degree) is reduced. As in the case of the first embodiment, the power supply system 2 requires the total remaining capacity of the storage batteries 33a to 33d during storage, and the lower limit value of the SOC allowed by the power supply system 2 in the storage period. The method of distributing the SOC of each of the storage batteries 33a to 33d may be changed as appropriate. Further, the SOC value of each of the storage batteries 33a to 33d during the storage period may be a predetermined value stored in the memory 31a, or may be appropriately determined by the controller 31 by calculation. Good.

  In the second embodiment, even when the power storage device 40 is charged and discharged, the SOCs of the four storage batteries 33a to 33d are not all the same, but are divided into two types. That is, the SOC is controlled to be different between the first set of the first storage battery 33a and the second storage battery 33b and the second set of the third storage battery 33c and the fourth storage battery 33d. In the example shown in FIG. 9, the SOC when the SOCs of the four storage batteries 33 a to 33 d are all the same as the average value of the first set of SOCs and the second set of SOCs during charging and discharging. The charge / discharge rates of the storage batteries 33a to 33d are determined so as to be the same as the assumed change pattern (broken line graph in FIG. 9).

  Aging also occurs during charging and discharging. For this reason, by controlling each storage battery 33a-33d like the example shown in FIG. 9, compared with the case where all four storage batteries 33a-33d are arrange | equalized with the same SOC, at the time of charging / discharging, four The average deterioration degree of the storage batteries 33a to 33d can be reduced. However, there is no effect of reducing the progress of deterioration at any time during charging and discharging, and in this example, the effect of reducing the progress of deterioration when the SOC of the first storage battery 33a and the second storage battery 33b exceeds 50%. (See graph in FIG. 3A).

  In the configuration of the second embodiment, the charge / discharge pattern may be changed as appropriate within a range that does not cause overdischarge, overcharge, or overcurrent. In addition, the average value of the first set of SOCs and the second set of SOCs during charging and discharging is controlled to be the same as the assumed SOC pattern when the SOCs are all aligned. You don't have to.

  Also in the configuration of the second embodiment, as in the first embodiment, a configuration in which the SOC allocation during the storage period of each of the storage batteries 33a to 33d is rotated at a predetermined timing may be employed. For example, as shown in FIG. 10, the SOC allocation in the storage period may be rotated using the timing at which each of the storage batteries 33a to 33d is discharged. In FIG. 10, after discharging, the SOC of the first storage battery 33a and the second storage battery 33b (SOC during the storage period) is switched from 25% to 75%, and the SOC of the third storage battery 33c and the fourth storage battery 33d is from 75%. It has been replaced by 25%.

  In FIG. 10, the horizontal axis represents time (one day's time), and the vertical axis represents the SOC of each of the storage batteries 33a to 33d. In FIG. 10, (a) shows the SOC change of the 1st storage battery 33a and the 2nd storage battery 33b, (b) shows the SOC change of the 3rd storage battery 33c and the 4th storage battery 33d. The broken line graph is an SOC change pattern in the case where the SOCs of the four storage batteries 33a to 33d are all the same, and are shown for comparison.

  In the configuration of the second embodiment, the DC-DC converters 32a to 32d included in the power storage device 40 may be replaced with switches. In this case, since storage batteries of different SOCs cannot be used at the same time, it is necessary to change the charge / discharge control of the storage batteries 33a to 33d.

<Others>
The embodiment described above is an exemplification of the present invention, and the power storage device and the power supply system of the present invention are not limited to the configuration described above. That is, the configuration of the embodiment described above can be changed as appropriate without departing from the spirit of the present invention.

  For example, in the embodiment described above, the number of storage batteries connected in parallel included in the power storage device is four. However, the present invention is not limited to this, and the number of storage batteries connected in parallel may be changed as appropriate. Further, the number of types of SOC set at the time of storage may be changed as appropriate. In some cases, the SOC set at the time of storage may be different for all the storage batteries.

  In addition, the power storage device and the power supply system of the present invention are not limited to stationary devices, and can be applied to moving bodies such as vehicles, ships, airplanes, robots, and power-assisted bicycles.

1, 2 Power supply system 10, 12 Commercial AC power supply (power supply source)
11 Solar power generation equipment (power supply source)
30, 40 Power storage device 31 Controller (control unit, part of adjusting means)
32a to 32d DC-DC converter (part of adjusting means)
33a-33d storage battery 34a-34d switch (part of adjusting means)

Claims (5)

A plurality of storage batteries connected in parallel;
Adjusting means provided so that the SOC of each of the plurality of storage batteries can be adjusted;
A power storage device comprising:
To save the total remaining capacity of the plurality of storage batteries as the predetermined value, SOC of the plurality of power storage pond, divided et is the double several,
The average deterioration degree of the plurality of storage batteries assumed from the deterioration information indicating the relationship between the SOC at the start of storage of the storage battery and the deterioration degree after the storage battery is stored for a predetermined period of time is determined for each of the storage batteries. The power storage device in which the SOC of each of the plurality of storage batteries is determined so as to be lower than the average deterioration degree of the plurality of storage batteries assumed from the deterioration information when the SOCs are all the same . The total remaining capacity of the plurality of storage batteries in the case of storing to a predetermined value, SOC assignment to the plurality of storage battery is replaced at a predetermined timing, power storage device according to claim 1. 3. The power storage device according to claim 1, wherein even when the plurality of storage batteries are charged and discharged, the SOCs of the plurality of storage batteries are not all the same but are divided into a plurality of types. Wherein the adjusting means includes a plurality of DC-DC converter, a control unit for controlling the plurality of DC-DC converter includes a power storage device according to any one of claims 1 to 3. A power supply source capable of supplying power to an external load;
The power storage device according to any one of claims 1 to 4 , wherein the power storage device is provided so as to be able to be charged with electric power from the power supply source, and is provided so as to be capable of being discharged with respect to an external load.
A power system.

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