JP6204902B2 - Charge / discharge control device and battery system having the same - Google Patents

Description

  The present invention relates to a charge / discharge control device and a battery system having the same.

  In a battery system having a plurality of power storage devices, there is a battery system that performs unit control for controlling the number of power storage batteries to be driven in accordance with supplied power or output power. For example, in Patent Document 1, a power command acquisition unit that acquires a power command and a power command for the number of operating power converters for each operating number of power converters based on the power command acquired by the power command acquisition unit. An index value acquisition unit that obtains an index value of the degree of effective utilization of power, an operation number determination unit that determines the number of operating power converters based on the index value acquired by the index value acquisition unit, and the number of operations An operation selection command unit that determines a power converter to be operated based on the number of operating units determined by the determination unit, outputs an individual power command for the power converter to be operated, and outputs a stop command for the power converter to be stopped Is described.

JP 2013-172567 A

  By controlling the driving of the plurality of power storage devices with the power control device described in Patent Document 1, it is possible to operate each power storage device with a charge rate within a target range. However, the power control device described in Patent Literature 1 has a problem that the charging device to be driven frequently switches depending on the relationship between the charging rates of the respective power storage devices. When the driving charging device is frequently switched, the operation efficiency is lowered due to the operation. Moreover, when control cannot follow, control cannot be performed appropriately.

  An object of this invention is to provide the charging / discharging control apparatus and battery system which can drive | operate an electrical storage apparatus efficiently.

  In order to achieve the above object, the present invention provides a charge / discharge control device that controls charging / discharging of a plurality of power storage devices, a charge rate acquisition unit that acquires a charge rate of the plurality of power storage devices, and a plurality of the power storage devices. Based on the charge rate, a charge / discharge target value acquisition unit that acquires a target value of charge / discharge output from the entire device, a priority switching timing generation unit that generates a switching timing for switching the priority of using the power storage device, and A priority order is determined, and a priority order determination unit that switches the priority order at the switching timing generated by the priority order switching timing generation unit, the priority order determined by the priority order determination unit, and the charge / discharge target value acquisition A power conversion command unit that determines the power storage device to be used based on the charge / discharge target value acquired by the unit, and executes charge / discharge from the determined power storage device, and the priority order The replacement timing generation unit calculates a cycle of the switching timing based on a reference capacity calculated based on a battery capacity of the power storage device and a preset allowable charge rate difference and a maximum charge / discharge current of the power storage device. The switching timing is output based on the calculated period.

  The priority switching timing generation unit sets the battery capacity of the power storage device to Ah [Wh], sets the allowable charge rate difference to α [%], sets the reference capacity to ΔC, and sets the maximum charge / discharge current to A [W], where the coefficient is B (0.8 ≦ B ≦ 1), the reference capacity ΔC is calculated based on the battery capacity Ah [Wh] of the power storage device and the allowable charge rate difference α, and the switching is performed. It is preferable to calculate the timing period T by T = B × ((60 × ΔC) / A).

  Moreover, it is preferable that the priority switching timing generation unit calculates the reference capacity ΔC by ΔC = Ah × (α / 100).

  The priority switching timing generation unit preferably calculates the reference capacity ΔC by ΔC = Ah × ((α−β) / 100), where β [%] is the dead zone charging rate difference corresponding to the dead zone. .

  The priority switching timing generation unit sets a difference in charging rate before switching, which is a difference in charging rate at the latest determination, to γ [%], and sets the reference capacity ΔC to ΔC = Ah × ((α + γ) / 100). It is preferable to calculate by.

  Further, the priority switching timing generation unit further sets the dead zone charging rate difference corresponding to the dead zone to β [%], and sets the charging rate difference before switching, which is the difference in charging rate at the latest determination, to γ [%], The reference capacity ΔC is preferably calculated as ΔC = Ah × ((α−β + γ) / 100).

  The coefficient B is preferably 1.

  The priority switching timing generation unit preferably outputs the switching timing with a period obtained by subtracting a time corresponding to a control delay from a period T of the switching timing.

  The present invention for achieving the above object is a battery system, the charge / discharge control device according to any one of the above, a plurality of power storage devices whose charge / discharge is controlled by the charge / discharge control device, and the charge / discharge device. And a host controller that outputs a target value of charge / discharge output from the entirety of the plurality of power storage devices to the discharge controller.

  The plurality of power storage devices preferably have the same performance.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the difference of the charging rate between electrical storage apparatuses becomes large, suppressing the frequency of switching of an electrical storage apparatus. Thereby, the power storage device can be operated efficiently.

FIG. 1 is a block diagram showing a schematic configuration of a battery system having a charge / discharge control device. FIG. 2 is a flowchart illustrating an example of a processing operation of the charge / discharge control device. FIG. 3 is an explanatory diagram for explaining an example of a processing operation of the charge / discharge control device. FIG. 4 is a flowchart illustrating an example of a processing operation of the charge / discharge control device. FIG. 5 is an explanatory diagram for explaining an example of a processing operation of the charge / discharge control device. FIG. 6 is a flowchart illustrating an example of a processing operation of the charge / discharge control device. FIG. 7 is an explanatory diagram for explaining an example of a processing operation of the charge / discharge control device.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment, and when there are two or more embodiments, what comprises combining each embodiment is also included.

  FIG. 1 is a block diagram showing a schematic configuration of a battery system having a charge / discharge control device. The battery system 10 includes a plurality of power storage devices 12, a power system 14, an electric wire 16, a charge / discharge control device 18, and a host control device 20. The battery system 10 only needs to include two or more power storage devices 12, and may include 100 or more power storage devices 12.

  The plurality of power storage devices 12 are connected to the electric wires 16 in parallel. Each of the plurality of power storage devices 12 includes a battery unit 30, a power conversion unit 32, and an SOC determination unit 34. Here, although the some charging device 12 of this embodiment has the difference by a manufacturing error, it has the basically same performance. Specifically, the charging device 12 has the same design values such as battery capacity and maximum charge / discharge current value. The battery unit 30 is a secondary battery such as a lead battery, and performs charging and discharging. The battery unit 30 can store power of a predetermined battery capacity. The power conversion unit 32 is disposed between the battery unit 30 and the electric wire 16. The power conversion unit 32 converts direct current into alternating current and converts the wake into direct current. Specifically, the power conversion unit 32 converts the power stored in the battery unit 30 from direct current to alternating current and outputs it to the wiring 16. The power conversion unit 32 converts alternating current power supplied from the wiring 16 into direct current, supplies the direct current to the battery unit 30, and charges the battery unit 30. The power conversion unit 32 switches between discharging from the battery unit 30 and charging the battery unit 30 based on the control of the charge / discharge control device 18. The SOC determination unit 34 detects the charge rate (State Of Charge) of the battery unit 30. The charging rate [%] is a ratio of the current capacity to the battery capacity of the battery unit 30. The SOC determination unit 34 sends the detected charging rate to the charge / discharge control device 18.

  The power storage device 12 controls the power conversion unit 32 based on the control of the charge / discharge control device 18 to discharge the battery unit 30 to the wiring 16 and charge the battery unit 30 with the power supplied from the wiring 16. . In addition, the power storage device 12 may be on standby based on the control of the charge / discharge control device 18 without performing charging or discharging. In addition, the power storage device 12 sends the charge rate detected by the SOC determination unit 34 to the charge / discharge control device 18.

  The power system 14 is a system having a generator for generating power and a load device that consumes power. In the power system 14, a state where the power generated by the generator is larger than the power consumed by the load device or a state where the power generated by the generator is smaller than the power consumed by the load device occurs. The power system 14 is connected to the plurality of power storage devices 12 via the electric wires 16. The electric wire 16 connects the plurality of power storage devices 12 and the power system 14.

  The host controller 20 will be described before the charge / discharge controller 18. The host controller 20 adjusts the generated power and the power consumption of the power generation system 10. The host controller 20 detects the balance between the generated power and the power consumption of the power system 14, and based on the detected result, the overall target value of the power charged by the plurality of charging devices 12, or the plurality of charging devices 12 The charge / discharge target value, which is the overall target value of the power discharged from the battery, is determined, and the determined charge / discharge target value is sent to the charge / discharge control unit 18.

  The charge / discharge control device 18 controls operations such as charging, discharging, and stopping of the plurality of power storage devices 12. In other words, the charge / discharge control device 18 controls the number of the plurality of power storage devices 12 to be driven, and further controls whether the driven power storage device 12 performs charging or discharging. The charge / discharge control device 18 also controls the current value to be charged / discharged. The charge / discharge control device 18 includes a power conversion command unit 50, a priority determination unit 52, a priority switching timing generation unit 54, a charge rate acquisition unit 56, and a charge / discharge target value acquisition unit 58.

  The power conversion command unit 50 determines charging, discharging, and stopping of each power storage device 12 and outputs a command value based on the determination to each power storage device 12. The power conversion command unit 50 determines charging, discharging, and stopping of each power storage device 12 based on the charging / discharging target value and the priority list generated by the priority determination unit 52 described later. The power conversion command unit 50 controls the power storage device 12 to be driven, thereby setting the total value of the charge / discharge power of each power storage device 12 as the charge / discharge target value.

  The priority order determination unit 52 determines the priority order based on the charging rate of each power storage device 12, and creates a priority list. The priority determination unit 52 creates and stores a discharge priority list 52a and a charge priority list 52. The discharge priority list 52a is a list of priorities of the power storage devices 12 to be driven when discharging from the power storage device 12, and the power storage devices 12 having a high charging rate are ranked in the order of higher priority. . The charging priority list 52b is a list of the priorities of the power storage devices 12 to be driven when charging from the power storage device 12, and the power storage devices 12 having a low charging rate are ranked in the order of increasing priority. . The priority determination unit 52 creates the discharge priority list 52a and the charge priority list 52b at the switching timing generated by the priority switching timing generation unit 54, and updates the list when there is a change.

  The priority switching timing generation unit 54 generates switching timing for executing processing for switching the priority. The priority switching timing generation unit 54 generates a cycle of switching timing and outputs the switching timing to the priority determination unit 52 based on the cycle. The priority switching timing generation unit 54 determines the cycle of the switching timing based on the reference capacity calculated based on the battery capacity of the power storage device 12 and the allowable charge rate difference and the maximum charge / discharge current of the power storage device 12. . The battery capacity and the maximum charge / discharge current of power storage device 12 are values determined by the performance of power storage device 12. The allowable charge rate difference is a value set in advance. The allowable charge rate difference is determined by the operator based on the overall configuration of the power generation system 10 and the characteristics of the power storage device 12. A method for determining the cycle of the switching timing will be described later.

  The charging rate acquisition unit 56 acquires information on the charging rate of each power storage device 12 output from the SOC determination unit 34 of each power storage device 12. The charge / discharge target value acquisition unit 58 acquires the charge / discharge target value output from the host controller 20. The charge / discharge target value acquisition unit 58 outputs the acquired charge / discharge target value to the power conversion command unit 50.

  The power generation system 10, when the host control device 20 detects that the power generated by the generator in the power system 14 is larger than the power consumed by the load device, the total target value of the power discharged from the plurality of power storage devices 12. Is output to the charge / discharge control device 18 as a charge / discharge target value. Based on the charge / discharge target value and the charge priority list 52b, the charge / discharge control device 18 selects the power storage devices 12 that are driven in descending order of priority so that the total charge amount becomes the power of the charge / discharge target value. To do. The power generation system 10 collects surplus power in the power system 14 by charging with the selected power storage device 12 having a high priority.

  When the power generation system 10 detects that the power generated by the generator is less than the power consumed by the load device, the power generation system 10 charges and discharges the total target value of the power discharged from the plurality of power storage devices 12. The target value is output to the charge / discharge control device 18. Based on the charge / discharge target value and the discharge priority list 52a, the charge / discharge control device 18 selects the power storage devices 12 that are driven in descending order of priority so that the total discharge amount becomes the power of the charge / discharge target value. To do. The power generation system 10 supplies necessary power to the power system 14 by discharging with the selected power storage device 12 having a high priority.

  Next, the control method of the electrical storage apparatus 12 by the charging / discharging control apparatus 18 of this embodiment is demonstrated. FIG. 2 is a flowchart illustrating an example of a processing operation of the charge / discharge control device. FIG. 3 is an explanatory diagram for explaining an example of a processing operation of the charge / discharge control device. The processing shown in FIG. 2 can be realized by executing processing in each unit of the charge / discharge control device 18.

  The charge / discharge control device 18 calculates the reference capacity ΔC and the period T by the priority switching timing generation unit 54 (step S12). Here, as described above, the priority order switching timing generation unit 54 calculates the reference capacity ΔC based on the battery capacity of the power storage device 12 and the preset allowable charge rate difference. The priority switching timing generation unit 54 calculates the switching timing period T based on the calculated reference capacity and the maximum charge / discharge current of the power storage device 12. Based on the reference capacity and the maximum charge / discharge current of the power storage device 12, the cycle T of the switching timing is determined. Reference capacity ΔC is calculated based on the battery capacity of the power storage device and the allowable charge rate difference.

Specifically, when the battery capacity of the power storage device 12 is Ah [Wh], the allowable charge rate difference is α [%], the maximum charge / discharge current is A [W], and the coefficient is B, the following formula is used. The capacity ΔC and the period T are calculated. Here, the coefficient B is 0.8 ≦ B ≦ 1.
ΔC = Ah × (α / 100)
T = B × ((60 × ΔC) / A)

  Next, the charge / discharge control device 18 determines whether the time T has elapsed from the previous determination by the priority determination unit 52 (step S14). That is, the charge / discharge control device 18 determines whether it is time to execute control for switching the priority order after the calculated period T has elapsed.

  When it is determined that the time T has not elapsed (No in step S14), the charge / discharge control device 18 proceeds to step S20. When the charge / discharge control device 18 determines that the time T has elapsed (Yes in step S14), the priority determination unit 52 determines whether there is a change in the discharge priority or the charge priority (step S16). That is, the priority order determination unit 52 determines whether or not the order is different between the stored discharge priority order list 52a and the current discharge priority order. Further, the priority order determination unit 52 determines whether or not the order is different between the stored charge priority list 52b and the current charge priority order. Here, the priority order determination unit 52 may always monitor the change in the discharge priority order or the charge priority order based on the charge rate sent from the power storage device 12 and acquired by the charge rate acquisition unit 56. During the process of determining whether there is a change in the discharge priority or the charge priority by the rank determination unit 52, the discharge priority or the charge priority at the time of the process may be detected.

  If the charge / discharge control device 18 determines that neither the discharge priority order nor the charge priority order is changed (No in step S16), the process proceeds to step S20. When it is determined that there is a change in either the discharge priority or the charge priority (Yes in step S16), the charge / discharge control device 18 switches the priority (step S18). That is, at least one of the discharge priority list 52a and the charge priority list 52b that has been changed in priority is switched.

  The charge / discharge control device 18 determines whether the control is completed when it is determined No in either step S14 or step S16 or when the process of step S18 is performed (step S20). When the charge / discharge control device 18 determines that the control is not finished (No in Step S20), the charge / discharge control device 18 returns to Step S14. That is, the charge / discharge control device 18 repeats the processing from step S14 to step S20 until it is determined that the control is finished. If the charge / discharge control device 18 determines that the control is terminated (Yes in step S20), the process is terminated.

  The charge / discharge control device 18 performs the process shown in FIG. 2 and calculates the reference capacity ΔC and the period T based on ΔC = Ah × (α / 100), T = B × ((60 × ΔC) / A). Then, by switching the priority order based on the calculated period T, it is possible to suppress the difference in the charging rate between the power storage devices 12 while suppressing the frequency of switching the priority order. Specifically, as shown in FIG. 3, the time T has elapsed even when the power storage device 1 and the power storage device 2 have the same charge rate and the discharge of only the power storage device 2 having a slightly higher charge rate is started. By switching the priority order again later, it is possible to suppress the difference in charging rate between the power storage device 1 and the power storage device 2 from becoming larger than the allowable SOC difference (allowable charging rate difference). That is, the charging / discharging control device 18 can set the charging rate difference between the power storage devices 12 within the management value (allowable charging rate difference) without frequently switching the priority order of charging / discharging. As described above, the charge rate between the power storage devices 12 connected in parallel can be equalized, so that reduction in the charge power and the discharge power in the entire battery system 10 can be suppressed. In addition, by performing priority switching processing every cycle T and reducing the frequency of switching priority, it is possible to suppress the occurrence of poor response due to time delay from the start of the power storage device 12 to power output. The risk of power fluctuation occurring at the timing of switching the power storage device 12 to be switched can be reduced, and the life of components used in the switching process can be extended.

  In addition, by setting the coefficient B between 0.8 and 1, it is possible to set a coefficient corresponding to the case where there is a variation in battery cells in the power storage device. In other words, by setting the coefficient to a value smaller than 1, even when there are variations in the performance of the power storage device, the priority switching timing frequently occurs while the charge rate difference is maintained within the allowable charge rate difference. This can be suppressed.

  Here, the charge / discharge control device 18 calculates the reference capacity ΔC based on the battery capacity of the power storage device 12 and a preset allowable charge rate difference, and the calculated reference capacity and the maximum charge / discharge current of the power storage device 12. Based on the above, the period T of the switching timing may be calculated, and various information may be added.

  Next, another example of the control operation by the charge / discharge control device 18 will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart illustrating an example of a processing operation of the charge / discharge control device. FIG. 5 is an explanatory diagram for explaining an example of a processing operation of the charge / discharge control device. The process shown in FIG. 4 can be realized by executing the process in each unit of the charge / discharge control device 18.

  The charge / discharge control device 18 calculates the reference capacity ΔC and the period T in consideration of the dead zone by the priority switching timing generation unit 54 (step S32). Here, the priority switching timing generation unit 54 calculates the reference capacity ΔC based on the battery capacity of the power storage device 12, the preset allowable charge rate difference, and the dead zone charge rate. The dead zone charging rate is a preset value. The priority switching timing generation unit 54 calculates the switching timing period T based on the calculated reference capacity and the maximum charge / discharge current of the power storage device 12. A cycle T of the switching timing is determined based on the reference capacity ΔC and the maximum charge / discharge current of the power storage device 12. Reference capacity ΔC is calculated based on the battery capacity of power storage device 12, the allowable charge rate difference, and the dead zone charge rate.

Specifically, when the dead zone charging rate corresponding to the dead zone is β [%], the reference capacity ΔC is calculated by the following formula.
ΔC = Ah × ((α−β) / 100)
The period T is calculated in the same manner as the above formula based on the reference capacity ΔC and the maximum charge / discharge current of the power storage device 12.

  Next, the charge / discharge control device 18 determines whether the time T has elapsed from the previous determination by the priority determination unit 52 (step S34). That is, the charge / discharge control device 18 determines whether it is time to execute control for switching the priority order after the calculated period T has elapsed.

  When it is determined that the time T has not elapsed (No in step S34), the charge / discharge control device 18 proceeds to step S42. If the charge / discharge control device 18 determines that the time T has elapsed (Yes in step S34), the priority determination unit 52 determines whether there is a change in the discharge priority or the charge priority (step S36).

  If the charge / discharge control device 18 determines that neither the discharge priority order nor the charge priority order is changed (No in step S36), the process proceeds to step S42. If the charge / discharge control device 18 determines that there is a change in either the discharge priority or the charge priority (Yes in step S36), is the maximum charge rate minus the minimum charge rate ≧ the dead zone charge rate? Is determined (step S38). That is, the charge / discharge control device 18 determines whether the difference between the maximum value of the charging rate and the minimum value of the charging rate is larger than the dead zone charging rate.

  The charge / discharge control device 18 determines that it is not the maximum value of the charging rate−the minimum value of the charging rate ≧ the dead zone charging rate (No in step S38), that is, the maximum value of the charging rate and the minimum value of the charging rate. When the difference is smaller than the dead zone charging rate, the process proceeds to step S42. When the charge / discharge control device 18 determines that the maximum value of the charging rate−the minimum value of the charging rate ≧ the dead zone charging rate (Yes in step S38), the charging / discharging control device 18 switches the priority (step S40). That is, when the priority is changed and the difference between the maximum value of the charging rate and the minimum value of the charging rate is larger than the dead zone charging rate, at least one of the discharging priority list 52a and the charging priority list 52b. Switch one side.

  The charge / discharge control device 18 determines whether the control is finished when it is determined No in any of step S34, step S36, and step S38, or when the process of step S40 is performed (step S42). If the charge / discharge control device 18 determines that the control is not finished (No in step S42), the charge / discharge control device 18 returns to step S34. That is, the charge / discharge control device 18 repeats the processing from step S34 to step S42 until it is determined that the control is finished. If the charge / discharge control device 18 determines that the control is complete (Yes in step S42), the process ends.

  The charge / discharge control device 18 performs the process shown in FIG. 4, calculates the reference capacity ΔC based on ΔC = Ah × (α−β / 100), and based on the cycle T calculated taking the dead zone charging rate into consideration. By switching the priority order, it is possible to suppress the difference in the charging rate between the power storage devices 12 while suppressing the frequency of switching the priority order. In addition, when the process shown in FIG. 4 is performed and the dead zone charging rate is taken into account, and the difference in charging rate is smaller than the dead zone charging rate, the priority list is not updated. Thereby, the frequency of priority switching can be further suppressed, and the occurrence of misjudgment in comparison of charging rates due to noise in the calculation result can be suppressed. Specifically, as shown in FIG. 5, when the charging rates of the power storage device 1 and the power storage device 2 are the same, the difference in the charging rate is smaller than the dead zone charging rate when switching to discharging with one unit. In this case, it is possible to further suppress the frequency of switching the priority order by continuously using the power storage device 2 without switching the priority order. Also in this case, by detecting the period T in consideration of the dead zone charging rate and the allowable charging rate difference, the difference between the charging rates of the power storage device 1 and the power storage device 2 is larger than the allowable SOC difference (allowable charging rate difference). It is possible to suppress the increase.

  Next, another example of the control operation by the charge / discharge control device 18 will be described with reference to FIGS. 6 and 7. FIG. 6 is a flowchart illustrating an example of a processing operation of the charge / discharge control device. FIG. 7 is an explanatory diagram for explaining an example of a processing operation of the charge / discharge control device. The processing shown in FIG. 6 can be realized by executing processing in each unit of the charge / discharge control device 18.

  The charge / discharge control device 18 determines whether the time T has elapsed from the previous determination by the priority determination unit 52 (step S52). That is, the charge / discharge control device 18 determines whether it is time to execute control for switching the priority order after the calculated period T has elapsed. The charge / discharge control device 18 determines that the time T has elapsed from the previous determination, although there is no previous determination when the control is started.

  When it is determined that the time T has not elapsed (No in step S52), the charge / discharge control device 18 proceeds to step S60. When it is determined that the time T has elapsed (Yes in step S52), the charge / discharge control device 18 calculates the reference capacity ΔC and the period T in consideration of the pre-switching charge rate (step S54). The pre-switching charging rate is a difference in charging rate of the target power storage device 12 at the time of determination. Here, the target power storage device 12 is the power storage device 12 having the highest priority and the next power storage device 12. That is, in the case of charging, the pre-switching charging rate is a difference in charging rate between the power storage device 12 with the lowest power storage rate and the second lowest power storage device 12. In the case of discharging, the pre-switching charging rate is a difference in charging rate between the power storage device 12 having the highest power storage rate and the second highest power storage device 12. The priority switching timing generation unit 54 calculates a reference capacity ΔC based on the battery capacity of the power storage device 12, a preset allowable charging rate difference, and the current charging rate before switching. The priority switching timing generation unit 54 calculates the switching timing period T based on the calculated reference capacity and the maximum charge / discharge current of the power storage device 12. A cycle T of the switching timing is determined based on the reference capacity ΔC and the maximum charge / discharge current of the power storage device 12. Reference capacity ΔC is calculated based on the battery capacity of power storage device 12, the allowable charge rate difference, and the dead zone charge rate.

Specifically, when the difference in electric power before switching is γ [%], the reference capacity ΔC is calculated by the following formula.
ΔC = Ah × ((α + γ) / 100)
The period T is calculated in the same manner as the above formula based on the reference capacity ΔC and the maximum charge / discharge current of the power storage device 12.

  After calculating the reference capacity ΔC and the cycle T, the charge / discharge control device 18 determines whether there is a change in the discharge priority or the charge priority by the priority determination unit 52 (step S56).

  If the charge / discharge control device 18 determines that neither the discharge priority order nor the charge priority order is changed (No in step S56), the process proceeds to step S60. When it is determined that there is a change in either the discharge priority or the charge priority (Yes in step S56), the charge / discharge control device 18 switches the priority (step S58). That is, when there is a change in priority, at least one of the discharge priority list 52a and the charge priority list 52b is switched.

  The charge / discharge control device 18 determines whether the control is finished when it is determined No in either step S52 or step S56 or when the process of step S58 is performed (step S60). When the charge / discharge control device 18 determines that the control is not finished (No in step S60), the charge / discharge control device 18 returns to step S52. That is, the charge / discharge control device 18 repeats the processing from step S52 to step S60 until it is determined that the control is finished. If the charge / discharge control device 18 determines that the control is complete (Yes in step S60), the process ends.

  The charge / discharge control device 18 performs the processing shown in FIG. 6, calculates the reference capacity ΔC based on ΔC = Ah × (α + γ / 100), and based on the cycle T calculated taking into account the charging rate before switching, Even by switching the priority order, it is possible to suppress the difference in the charging rate between the power storage devices 12 while suppressing the frequency of switching the priority order. Further, by adding the pre-switching charge rate, the cycle T can be lengthened when the difference in charge rate is large, and the cycle T can be shortened when the difference in charge rate is small. Thereby, the length of the period T can be adjusted according to the current state, so that the determination interval can be lengthened while suppressing the difference in the charging rate from becoming larger than the allowable charging rate difference. The switching frequency can be further suppressed. Specifically, as shown in FIG. 7, the difference between the charge rates of the power storage device 1 and the power storage device 2 is detected as the pre-switching charge rate, and the cycle T is obtained by adding the pre-switching charge rate. Even when only the power storage device 1 with the highest priority is used after switching to discharge by one unit, the difference between the charge rates of the power storage device 1 and the power storage device 2 when the period T elapses is the allowable SOC difference (allowable (Charge rate difference) can be suppressed.

  Further, the charging / discharging control device 18 takes into account both the dead zone charging rate difference β [%] corresponding to the dead zone and the charging rate difference γ [%] before switching, which is the difference between the charging rates at the latest determination, The reference capacity ΔC may be calculated by ΔC = Ah × ((α−β + γ) / 100). Thereby, both effects of the example mentioned above can be acquired.

  Further, in the present embodiment, the discharge priority list 52a and the charge priority list 52b are stored separately, but both are determined based on the charging rate, and the priority criterion is reversed. One priority list may be used, and switching from the upper level or the lower level may be switched according to each case.

  The priority switching timing generation unit 54 may set a new period T by subtracting the time corresponding to the control delay from the calculated switching timing period T. That is, the T-control delay time may be set as a new cycle (time) T. Thereby, control delay can be considered and it can suppress that the difference of the charging rate between the electrical storage apparatuses 12 opens too much.

  The coefficient B is preferably 1. Thereby, the period T can be made longer and the switching timing can be made longer.

DESCRIPTION OF SYMBOLS 10 Battery system 12 Power storage apparatus 14 Electric power system 16 Electric wire 18 Charging / discharging control apparatus 20 Host control apparatus 30 Battery part 32 Power conversion part 34 SOC determination part 50 Power conversion command part 52 Priority determination part 52a Discharge priority list 52b Charging priority order List 54 Priority switching timing generation unit 56 Charging rate acquisition unit 58 Charge / discharge target value acquisition unit

Claims (10)

A charge / discharge control device for controlling charge / discharge of a plurality of power storage devices,
A charge rate acquisition unit for acquiring the charge rates of the plurality of power storage devices;
A charge / discharge target value acquisition unit for acquiring a target value of charge / discharge output from the entirety of the plurality of power storage devices;
A priority switching timing generating section for generating a switching timing for switching the priority of using the power storage device;
A priority order determination unit that determines a priority order based on a charging rate, and switches the priority order at the switching timing generated by the priority order switching timing generation unit;
Based on the priority order determined by the priority order determination unit and the charge / discharge target value acquired by the charge / discharge target value acquisition unit, the power storage device to be used is determined, and charging / discharging is performed from the determined power storage device. And a power conversion command unit to be executed,
The priority switching timing generation unit is configured to change the switching timing based on a reference capacity calculated based on a battery capacity of the power storage device and a preset allowable charge rate difference and a maximum charge / discharge current of the power storage device. The charge / discharge control apparatus is characterized in that the cycle is calculated and the switching timing is output based on the calculated cycle.   The priority switching timing generation unit sets the battery capacity of the power storage device to Ah [Wh], sets the allowable charge rate difference to α [%], sets the reference capacity to ΔC, and sets the maximum charge / discharge current to A [W And the coefficient is B (0.8 ≦ B ≦ 1), the reference capacity ΔC is calculated based on the battery capacity Ah [Wh] of the power storage device and the allowable charge rate difference α, and the switching timing The charge / discharge control apparatus according to claim 1, wherein the period T is calculated by T = B × ((60 × ΔC) / A).   The charge / discharge control apparatus according to claim 2, wherein the priority switching timing generation unit calculates the reference capacity ΔC by ΔC = Ah × (α / 100).   The priority switching timing generation unit calculates a difference in the dead zone charging rate corresponding to the dead zone as β [%], and calculates the reference capacity ΔC by ΔC = Ah × ((α−β) / 100). The charge / discharge control apparatus according to claim 2.   The priority switching timing generation unit calculates the reference charging capacity ΔC as ΔC = Ah × ((α + γ) / 100), assuming that the charging rate difference before switching, which is the difference in charging rate at the latest determination, is γ [%]. The charge / discharge control apparatus according to claim 2, wherein:   The priority switching timing generation unit further sets the dead zone charging rate difference corresponding to the dead zone to β [%], and sets the charging rate difference before switching, which is the difference in charging rate at the latest determination, to γ [%]. The charge / discharge control device according to claim 2, wherein the capacity ΔC is calculated by ΔC = Ah × ((α−β + γ) / 100).   The charge / discharge control apparatus according to any one of claims 2 to 6, wherein the coefficient B is 1.   8. The priority order switching timing generation unit outputs the switching timing with a period obtained by subtracting a time corresponding to a control delay from a period T of the switching timing. Charge-discharge control apparatus as described in. The charge / discharge control device according to any one of claims 1 to 8,
A plurality of power storage devices whose charge / discharge is controlled by the charge / discharge control device,
A battery system comprising: a higher-order control device that outputs a charge / discharge target value output from the entirety of the plurality of power storage devices to the charge / discharge control device.   The battery system according to claim 9, wherein the plurality of power storage devices have the same performance.

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