JP5113789B2 - Charge / discharge control device and charge / discharge control method - Google Patents

Description

  The present invention relates to a charge / discharge control technique for suppressing output fluctuation of a natural energy power generation apparatus.

  Natural energy generators that use natural energy, such as wind power generation and solar power generation, fluctuate in the generated power due to changes in natural conditions. There is a possibility of adverse effects such as frequency fluctuations and voltage fluctuations. As one of countermeasures, a method has been proposed in which a power storage device is provided in addition to a natural energy power generation device to suppress voltage fluctuations in the power system. For example, a power storage device that compensates for output fluctuations of a natural energy power generation device described in Patent Document 1 includes two batteries and periodically switches between discharging and charging to compensate for output fluctuations of the natural energy power generation device. It is.

JP 2001-157382 A

  However, in the power storage device described in Patent Document 1, the switching period between discharging and charging is determined in advance according to the rated capacity of the power storage device (see paragraphs 0022 and 0024). Therefore, there is a problem that it is not possible to adaptively switch between discharging and charging between batteries constituting the power storage device while adapting to a large output fluctuation when the amount of introduction of the natural energy power generation device increases. Then, this invention makes it a subject to provide the charging / discharging control technique which can perform charging / discharging management of a battery adaptively, suppressing the output fluctuation | variation of a natural energy power generation device to a regulation range.

  In order to solve the above-mentioned problem, the charge / discharge control device according to the present invention includes a plurality of units in which a power converter (inverter and converter) is connected in parallel to a battery (including a case where a plurality of single cells are connected in series). In order to control the power storage device, a power converter controller that controls charge / discharge of each unit, a group controller that performs charge / discharge control with a plurality of the power converter controllers as one group, and the group controller And an overall controller for controlling charging / discharging of the entire power storage device, and the output fluctuation of the natural energy power generation device is suppressed within a specified range.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the charging / discharging control technique which can perform charging / discharging management of a battery adaptively, suppressing the output fluctuation of a natural energy power generation device to a regulation range.

It is a figure which shows the structure of the electric power system in this embodiment. It is a figure which shows the structural example of a general controller. It is a figure which shows the outline | summary of the allocation method in a group charge / discharge command value distribution part, (a) is a figure which shows the case of discharge, (b) is a figure which shows the case of charge. It is a figure which shows the flow (in the case of discharge) of the process in a group charge / discharge command value distribution part. It is a figure which shows the flow (in the case of charge) of the process in a group charge / discharge command value distribution part. It is a figure which shows the structural example of a group controller. It is a figure which shows the structural example of a power converter controller. It is a figure which shows the example of the gate pulse stop method. It is a figure which shows the example of the time passage of the charging / discharging state of each unit at the time of recovery charge.

  Next, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate.

The configuration of the power system 1 in the present embodiment will be described with reference to FIG.
As shown in FIG. 1, the power system 1 is configured such that the sum of the power PN output from the natural energy power generation device 80 and the power PB output from the power storage device 100 (discharge is positive and charge is negative) The point A is adjusted so as to be the system power PS of the power system 90. The natural energy power generation device 80 is a wind power generation device, a solar power generation device, or the like. Therefore, the electric power PN fluctuates due to changes in natural energy. Therefore, power storage device 100 absorbs fluctuations in power PN and controls charging / discharging of battery 60 provided in power storage device 100 so that system power PS falls within a specified fluctuation range. The battery 60 is a secondary battery, and is a lead battery, a NaS (sodium sulfur) battery, an electric double layer capacitor, a redox flow battery, or the like.

  The power storage device 100 includes the battery 60 and the power converter 50 as a unit 51, connects the units 51 in parallel, and outputs power PB via the transformer 70. The number of units 51 is about 100, for example. Charge / discharge management including recovery charge of the battery 60 is performed by the charge / discharge control device 10 in units of units 51.

  The charge / discharge control device 10 according to the present embodiment includes an overall controller 20 that controls the entire power storage device 100 and controls electric power PB that is an output of the power storage device 100. A plurality of group controllers 30 are provided under the overall controller 20. The group controller 30 controls the plurality of units 51 as a group 52. The group controller 30 controls the power converter 50 of the unit 51 via the power converter controller 40 and manages charge / discharge of the unit 51. For example, the number of units 51 managed as one group 52 is about ten. Therefore, if the number of units 51 is about 100, the number of group controllers 30 is about 10. Note that a programmable logic controller or a microcomputer having a control operation function is used for the overall controller 20 and the group controller 30.

  Next, a configuration example of the overall controller 20 will be described with reference to FIG. 2 (see FIG. 1 as appropriate). The overall controller 20 includes a power storage device output correction unit 21, a storage unit 22 that holds an output target value PST of the power system 1 set in advance by an operator or the like, and a group charge / discharge command value distribution unit 23. The output target value PST of the power system 1 held in the storage unit 22 is a target value of the system power PS.

  The power storage device output correction unit 21 integrates the difference between the system power PS and the output target value PST of the power system 1 over a predetermined time, and outputs a power storage device output correction value PSC. The power storage device output correction value PSC includes compensation for wiring from each unit 51 to the connection point A, impedance drop of the transformer 70, and the like. Further, in this power storage device output correction value PSC, when an auxiliary device of the power storage device 100 (such as an air conditioner for maintaining the operating environment of the power storage device 100) is supplied with power from the power storage device 100, The power consumption compensation is included.

  Furthermore, the overall controller 20 adds the power storage device output correction value PSC and the output target value PST of the power system 1 and performs a calculation of subtracting the power PN that is the output of the natural energy power generation device 80 from the added value. By this calculation, charge / discharge command value PBR for controlling electric power PB that is the output of power storage device 100 is calculated.

  Next, the group charge / discharge command value distribution unit 23 determines a group charge / discharge command value PBGRx to be distributed to each group controller 30 (30x) based on a process described later. Note that x is an identifier of the group controller 30 (30x). Then, the overall controller 20 transmits a group charge / discharge command value PBGRx to each group controller 30x.

  Here, an overview of the distribution method in the group charge / discharge command value distribution unit 23 (when the number of groups is 3) will be described with reference to FIG. 3 (see FIGS. 1 and 2 as appropriate). In FIG. 3, the group 52 is represented as G1, G2, G3 (Gx). In the case of the discharge shown in FIG. 3A, first, the SOC (State of Charge) of each group G1, G2, G3 is calculated by integrating the output current of the battery 60. In addition, SOC represents the amount of electricity charged with respect to the battery capacity as a ratio. In the case of discharging, priority is given to the groups G1 to G3 in descending order of SOC, and the charge / discharge command value PBR is distributed. In FIG. 3A, the SOC is expressed in the order of G1, G2, and G3. That is, the priority order is G1, G2, G3 from the top.

  Next, the group charge / discharge command value distribution unit 23 determines a group Gx for distributing the charge / discharge command value PBR from the charge / discharge command value PBR and the maximum discharge output values PBGP1 to PBGP3 of the groups G1 to G3. In the case of FIG. 3A, since the charge / discharge command value PBR is larger than the maximum discharge output value PBGP1 and not more than PBGP1 + PBGP2, the charge / discharge command value PBR is distributed to the group G1 and the group G2. Note that the distribution to the group G3 is zero.

As shown in the following equation, the distribution ratio is the ratio of the discharge maximum output value of each group to the total discharge maximum output value of the entire group to be distributed. Therefore, the group charge / discharge command value PBGRx allocated to each group Gx is calculated as follows by multiplying the charge / discharge command value PBR by the ratio.
PBGR1 = PBR × PBGP1 / (PBGP1 + PBGP2)
PBGR2 = PBR × PBGP2 / (PBGP1 + PBGP2)
PBGR3 = 0

  Next, as shown in FIG.3 (b), in the case of charge, priority is given to each group G1-G3 in order with low SOC, and charge / discharge command value PBR is allocated. That is, the priority order is the reverse of the case of discharging, and is in the order of G3, G2, and G1 from the top.

  Next, a group Gx to which the charge / discharge command value PBR is allocated is determined from the charge / discharge command value PBR and the maximum charge output values PBGN1 to PBGN3 of the groups G1 to G3. In the case of FIG. 3B, since the charge / discharge command value PBR is smaller than the maximum charge output value PBGN3 and is equal to or greater than PBGN3 + PBGN2, the charge / discharge command value PBR is distributed to the group G3 and the group G2. The distribution to the group G1 is zero.

As shown in the following equation, the distribution ratio is the ratio of the maximum charge output value of each group to the total charge maximum output value of the entire group to be distributed. Therefore, the group charge / discharge command value PBGRx allocated to each group Gx is calculated as follows by multiplying the charge / discharge command value PBR by the ratio.
PBGR1 = 0
PBGR2 = PBR × PBGN2 / (PBGN3 + PBGN2)
PBGR3 = PBR × PBGN3 / (PBGN3 + PBGN2)

  The process flow in the group charge / discharge command value distribution unit 23 will be described with reference to FIGS. 4 and 5 (see FIGS. 1 and 3 as appropriate). FIG. 4 shows the case of discharge. First, for each group 52, the priority order for using the group 52 for discharging is determined in descending order of SOC (step S401). Then, it is determined whether there is a group 52 having the same SOC (step S402). When there is a group 52 having the same SOC (Yes in step S402), the order with the smaller integrated discharge amount is given priority between the groups 52 having the same SOC (step S403). Thereby, even when SOC is equal, the integrated discharge amount between groups can be equalized, and as a result, the progress of battery deterioration in a specific group can be prevented. The accumulated discharge amount is a value obtained by integrating the discharge current or discharge power of the battery. When the integrated discharge amounts are also equal, for example, the smaller number identifying the group 52 is set as the higher priority. Note that if No in step S402, step S403 is skipped. Through the processing up to step S403, a rearrangement function g (i) for rearranging the highest i-th priority order to a number (symbol) k identifying the group 52 is calculated (step S404). That is, k = g (i).

  Next, a determination process for the group 52 to which the charge / discharge command value PBR is allocated is performed. In step S405, initial values P = 0, i = 0, and PBGRj = 0 are set for all j. Then, i = i + 1 is calculated, and the discharge maximum output value PBGPi of the i-th group 52i with the highest priority is added to P (step S406). Then, it is determined whether i is the last (step S407). If i is not the last (No in step S407), it is determined whether the charge / discharge command value PBR is equal to or less than P (step S408). When the charge / discharge command value PBR is equal to or less than P (Yes in step S408), each group charge / discharge command value PBGRx is calculated by equation (1) (step S409).

For k = g (j) where 1 ≦ j ≦ i, group charge / discharge command value PBGRk is expressed by equation (1).

  If i is the last in step S407 (Yes in step S407), step S408 is skipped. If PBR is larger than P in step S408 (No in step S408), the process returns to step S406.

  FIG. 5 shows the case of charging. First, for each group 52, the priority order for charging the group 52 in order of increasing SOC is determined (step S501). Then, it is determined whether there is a group 52 having the same SOC (step S502). When there is a group 52 having the same SOC (Yes in step S502), the rank is determined by giving priority to the one with the smaller integrated charge amount between the groups 52 having the same SOC (step S503). Thereby, even when SOC is equal, the charge integration amount between groups can be equalized, and as a result, progress of battery deterioration of a specific group can be prevented. The charge integration amount is a value obtained by integrating the charging current or charging power of the battery. If the integrated charge amounts are also equal, for example, the smaller number identifying the group 52 is set as the higher priority. Note that, if No in step S502, step S503 is skipped. Through the processing up to step S503, a rearrangement function g (i) for rearranging the highest i-th priority in order to the number (symbol) k identifying the group 52 is calculated (step S504). That is, k = g (i).

  Next, a determination process for the group 52 to which the charge / discharge command value PBR is allocated is performed. In step S505, initial values P = 0, i = 0, and PBGRj = 0 are set for all j. Then, i = i + 1 is calculated, and the charging maximum output value PBGNi of the i-th group 52i with the highest priority is added to P (step S506). Then, it is determined whether i is the last (step S507). If i is not the last (No in step S507), it is determined whether the charge / discharge command value PBR is equal to or greater than P (step S508). When the charge / discharge command value PBR is equal to or greater than P (Yes in step S508), each group charge / discharge command value PBGRx is calculated by equation (2) (step S509).

For k = g (j) when 1 ≦ j ≦ i, group charge / discharge command value PBGRk is expressed by equation (2).

  If i is the last in step S507 (Yes in step S507), step S508 is skipped. If PBR is less than P in step S508 (No in step S508), the process returns to step S506.

  As shown in FIGS. 3 to 5, the charge / discharge command value PBR of the entire power storage device 100 is distributed according to the SOC of each group 52x and the maximum discharge output value PBGPx or the maximum charge output value PBGNx of the power converter 50. As a result, it is possible to equalize the SOC for each group 52x. The SOC, discharge maximum output value PBGPx, and charge maximum output value PBGNx of each group 52x are acquired from each power converter controller 40 in the group 52x by the group controller 30x and transmitted to the overall controller 20.

  Next, a configuration example of the group controller 30 will be described with reference to FIG. 6 (see FIG. 1 as appropriate). As shown in FIG. 6, the group controller 30 includes a unit recovery charge management unit 31 that manages recovery charge of each unit 51, a group output correction unit 32 that calculates a group output correction value PBGRCx of the group 52, and a group charge / discharge command. A unit charge / discharge command value distribution unit 33 for calculating a unit charge / discharge command value PBURxn for distributing the value PBGRRx to each unit 51 is provided. Note that x represents a group identifier, and n represents a unit identifier.

  The unit recovery charge management unit 31 determines the recovery charge timing of each battery 60 in the group 52, receives the power PN that is the output of the natural energy power generation device 80, and sets the magnitude of the power PN to a predetermined value (regulation). And a recovery charge command value PSTRxn is transmitted to each power converter controller 40 based on the comparison result. In addition, when the power PN that is the output of the natural energy power generation device 80 becomes smaller than the specified value during the recovery charge, the unit recovery charge management unit 31 instructs each power converter controller 40 to temporarily stop the recovery charge. Send. Then, the unit recovery charge management unit 31 performs recovery charge management of the battery 60 in units of groups 52.

  The group output correction unit 32 integrates a difference between the group charge / discharge command value PBGRx and the group output PBGx for a predetermined time to calculate a group output correction value PBGRCx. Then, group controller 30 adds group charge / discharge command value PBGRx and group output correction value PBGRCx to calculate group charge / discharge command value PBGRRx. This group charge / discharge command value PBGRRx includes a power loss compensation amount from each unit 51 to the interconnection point B of each group 52. Further, the integration time constant of group output correction unit 32 is adjusted in coordination with the integration time constant of power storage device output correction unit 22 shown in FIG. 2 in order to compensate for power loss related to power storage device 100 as a whole.

  Unit charge / discharge command value distribution unit 33 calculates unit charge / discharge command value PBURxn to be distributed to each unit 51 from group charge / discharge command value PBGRRx. Then, the unit charge / discharge command value distribution unit 33 transmits the calculated unit charge / discharge command value PBURxn to each power converter controller 40. The distribution method used in unit charge / discharge command value distribution unit 33 is the same as the distribution method in group charge / discharge command value distribution unit 21 (see FIG. 2). That is, in the distribution method, the group 52 in the group charge / discharge command value distribution unit 21 may be replaced with the unit 51 in the unit charge / discharge command value distribution unit 33.

  As described above, the group charge / discharge command value PBGRRx of the group 52 is distributed according to the SOC of each unit 51xn and the maximum discharge output value PBGPxn or the maximum charge output value PBGNxn of the power converter 50, so that the SOC for each unit is obtained. It becomes possible to equalize. The SOC, discharge maximum output value PBGPxn, and charge maximum output value PBGNxn of each unit xn are acquired by the power converter controller 40xn and transmitted to the group controller 30x.

  Next, a configuration example of the power converter controller 40 will be described with reference to FIG. As shown in FIG. 7, the power converter controller 40 includes a recovery charging unit 41 that performs recovery charging of the battery 60, a power control unit 42 that controls output power of each unit 51, and each power converter 50 with PWM (Pulse The PWM current control part 43 to control is provided.

  The recovery charging unit 41 receives the recovery charge command value PSTRxn from the group controller 30 and performs recovery charge control for suppressing the life and capacity reduction of the battery 60 such as constant current and constant voltage.

  The power control unit 42 receives the unit charge / discharge command value PBURxn from the group controller 30 and controls the output power of each unit 51.

  The PWM current control unit 43 controls the output current of each unit 51 according to the output of the recovery charging unit 41 or the power control unit 42. Then, the PWM current control unit 43 generates a gate pulse GPLSxn for driving each power converter 50xn, and stops the output of the gate pulse when the unit charge / discharge command value PBURxn is zero. Thereby, it is possible to eliminate the switching loss of power converter 50 that does not contribute to the suppression of fluctuations in power, and to reduce the power loss of power storage device 100 as a whole. Further, when the PWM current control unit 43 detects the input of the unit charge / discharge command value PBURxn, the PWM current control unit 43 cancels the stop of the output of the gate pulse and starts immediately.

  Here, an example of a gate pulse stopping method will be described with reference to FIG. As shown in FIG. 8, the gate pulse GPLSxn is generated at the intersection of the PWM modulated wave and the carrier wave. And in the period of unit charging / discharging command value PBURn = 0, the power converter controller 40 stops the output of a gate pulse using a stop signal.

  Next, a specific example of the operation of each unit 51 during recovery charging (when the number of units is 3) will be described with reference to FIG. 9 (see FIGS. 1 and 6 as appropriate). The horizontal axis in FIG. 9 represents time, and the vertical axis represents the power of the unit 51. The positive side is the discharge area and the negative side is the charge area.

  As shown in FIG. 9, each unit 51 (51aa, 51ab, 51ac) suppresses fluctuations in the power PN that is the output of the natural energy power generation device 80 in all units 51 until time T1. From time T1, the unit recovery charge management unit 31 of the group controller 30 does not adversely affect the output fluctuation control using the maximum discharge value PBGPaa of the power converter 50aa for the recovery charge of the unit 51aa. , Gradually narrow down to zero. The discharge power of the units 51ab and 51ac increases so as to compensate for the decrease in the maximum discharge output value PBGPaa of the power converter 50aa.

  Then, recovery charging of the unit 51aa is started from the time T2. Between times T2 and T3, recovery charging of the unit 51aa is performed, and power compensation is performed by the units 51ab and 51ac. Between times T3 and T4, the power PN that is the output of the natural energy power generation device 80 has become smaller than the specified value, so that the recovery charging is temporarily stopped. Therefore, the charging power of the unit 51aa is gradually returned to zero from time T3. Accordingly, the discharge power of the units 51ab, ac decreases. Then, at time T4, when the power PN that is the output of the natural energy power generation device 80 again becomes equal to or higher than the specified value, recovery charging of the unit 51aa starts, and the discharge power of the units 51ab and 51ac increases.

  As described above, the charge / discharge control device 10 of the power storage device 100 (see FIG. 1) of the present embodiment charges the power by connecting the units 51 having the battery 60 (secondary battery) and the power converter 50 as units. In order to control the power storage device 100 to be discharged, the overall controller 20 and a plurality of group controllers 30 are provided under its control. The group controller 30 further controls the power converters 50 of the plurality of units 51 via the power converter controller 40. The overall controller 20 controls the power PB that is the output of the power storage device 100 based on the power PN that is the output of the natural energy power generation device 80, the system power PS of the power system 90, and the output target value PST of the power system 1. A command value PBR is generated, and the command value PBR is distributed to each group controller 30x. Each group controller 30 further distributes the command value PBGRx to the power converter controller 40 based on the power PBGx that is the output of the group 52x and the command value PBGRx distributed from the overall controller 20. Therefore, it is possible to adaptively manage the charge / discharge amount of the battery while suppressing the fluctuation of the power PN, which is the output of the natural energy power generation device 80, within a specified range.

The overall controller 20 determines the group charge / discharge command value PBGRx according to the magnitude of the maximum discharge output value PBGPx and the maximum charge output value PBGNx of each group 52x. Then, the group controller 30 determines the unit charge / discharge command value PBURxn according to the magnitudes of the maximum discharge output value PBGPxn and the maximum charge output value PBGNxn of each unit 51xn. Therefore, it is possible to achieve uniform SOC between the groups 52 or uniform SOC of the batteries 60 in the group 52.
When unit charge / discharge command value PBURxn is zero, the output of the gate pulse for driving power converter 50 is stopped to eliminate the switching loss, thereby reducing the power loss of power storage device 100 as a whole.

Further, by using the output target value PST of the power system 1, it is possible to compensate for the power loss due to the equipment from the unit 51 to the interconnection point A of the power system and to supply the grid power PS stably. Is possible.
Further, since the control device is configured by the hierarchical structure of the general controller 20, the group controller 30, and the power converter controller 40, when the number of units 51 increases, the program of the group controller 30 is changed or added. It is possible to easily cope with this.

DESCRIPTION OF SYMBOLS 1 Electric power system 10 Charge / discharge control apparatus 20 General controller (3rd controller)
21 Group charge / discharge command value distribution unit 22 Power storage device output correction unit 30 Group controller (second controller)
31 Unit recovery charge management unit 32 Group output correction unit 33 Unit charge / discharge command value distribution unit 40 Power converter controller (first controller)
41 Recovery Charging Unit 42 Power Control Unit 43 PWM Current Control Unit 50 Power Converter 51 Unit 60 Battery 70 Transformer 80 Natural Energy Power Generation Device 90 Power System 100 Power Storage Device

Claims (14)

A system power that is a sum of output power of a power storage device that charges and discharges by connecting a plurality of the units in parallel and a power output of a natural energy power generation device is a predetermined power. A charge / discharge control device for controlling the output power of the power storage device so as to fall within a range,
A first controller for individually controlling the power converter of the unit;
A second controller that controls a plurality of the units as a group and that controls the output power of the group via the first controller;
A third controller that distributes the charge / discharge command value of the entire power storage device used for controlling the output power of the power storage device as a group charge / discharge command value for each second controller;
With
The second controller adjusts the output power of the unit via the first controller based on the group charge / discharge command value, and controls the system power to fall within a predetermined range. Charge / discharge control device. The third controller includes a processing unit and a storage unit that stores a target value of the grid power,
The processing unit is
Obtain the grid power and the output power of the natural energy power generation device,
A value obtained by subtracting the system power from the target value of the system power based on the acquired system power and the output power of the natural energy power generation device and the target value of the system power, and integrating the subtraction value for a predetermined time The charging / discharging command value for the entire power storage device is calculated by adding the target value of the grid power and subtracting the output power of the natural energy power generation device from the added value. The charge / discharge control apparatus as described. The third controller uses an SOC (State of Charge) calculated based on the output current of the secondary battery, and either or both of a maximum discharge output value and a maximum charge output value for each group. The charge / discharge control device according to claim 1, wherein the group charge / discharge command value is calculated from a charge / discharge command value of the entire power storage device. The third controller selects a group to be used for discharging in descending order of the SOC in the case of a discharge that becomes a positive charge / discharge command value of the entire power storage device that is larger as a discharge output value is larger. For the group selected immediately before the maximum value of discharge exceeds the charge / discharge command value for the entire power storage device, 4. The charge / discharge control according to claim 3, wherein a ratio of the discharge maximum output value of the group is calculated, and the group discharge command value is calculated according to the charge / discharge command value of the entire power storage device according to the ratio. apparatus. The third controller selects a group to be used for charging in ascending order of the SOC in the case of charging that becomes a negative charging / discharging command value of the entire power storage device that is larger as the charging output value is larger. For the group that was selected immediately before the maximum charging value of the group was added in order, the added value was below the charging / discharging command value for the entire power storage device, the total charging maximum output value of the group 4. The charging according to claim 3, wherein a ratio of the charging maximum output value of each individual group to the battery is calculated, and the charging / discharging command value of the entire power storage device is calculated according to the ratio. Discharge control device.   When there is a group having the same SOC, the third controller charges a group with a small integrated discharge amount when the charge / discharge command value of the entire power storage device is discharged, and the charge / discharge command value of the entire power storage device is charged. 4. The charge / discharge control device according to claim 3, wherein the group discharge command value and the group charge command value are distributed with priority given to a group having a small charge integration amount. The second controller subtracts the output power of the own group from the group charge / discharge command value based on the acquired output power of the own group and the group charge / discharge command value, and sets the subtraction value to a predetermined value. The charge / discharge control apparatus according to claim 1, wherein the charge / discharge command value of the group is calculated by adding the group charge / discharge command value to the time-integrated value. The second controller uses the SOC calculated based on the output current of the secondary battery and one or both of the discharge maximum output value and the charge maximum output value for each unit, and performs the group charge / discharge. The charge / discharge control apparatus according to claim 1, wherein a unit charge / discharge command value for adjusting output power of the unit is calculated from the command value. In the case of a discharge that becomes a larger positive group charge / discharge command value as the discharge output value is larger, the second controller selects units to be used for discharging in order of higher SOC, and When the maximum discharge output value is added in order, for each unit selected immediately before the added value exceeds its own group charge / discharge command value, the individual units for the total discharge maximum output value of the unit The charge / discharge control device according to claim 8, wherein a ratio of the maximum discharge output value is calculated, and the unit discharge command value is calculated according to the ratio of the own group charge / discharge command value. In the case of charging with the negative group charging / discharging command value as the charging output value increases, the second controller selects units to be used for charging in ascending order of the SOC. When the maximum charge output value is added in order, the unit selected immediately before the added value falls below the group charge / discharge command value, the individual unit's total charge maximum output value of the unit is selected. The charge / discharge control apparatus according to claim 8, wherein a ratio of a maximum charge output value is calculated, and the unit charge command value is calculated according to the ratio of the group charge / discharge command value.   When there is a unit having the same SOC, the second controller sets a unit having a small integrated discharge amount when the group charge / discharge command value is discharged, and sets a charge integrated amount when the group charge / discharge command value is charged. 9. The charge / discharge control device according to claim 8, wherein the unit discharge command value and the unit charge command value are distributed with priority given to a small number of units. The second controller acquires the output power of the natural energy power generation device, and instructs the first controller to stop recovery charging when the acquired output power of the natural energy power generation device is smaller than a predetermined value. Output to
The charge / discharge control apparatus according to claim 1, wherein the first controller performs control to stop recovery charging when receiving an instruction to stop the recovery charging. The first controller includes:
A PWM current control unit that performs PWM (Pulse width modulation) control on the power converter of the unit,
The charge / discharge control apparatus according to claim 1, wherein the PWM current control unit stops the output of the gate pulse when the unit discharge command value is zero. A system power that is a sum of output power of a power storage device that charges and discharges by connecting a plurality of the units in parallel and a power output of a natural energy power generation device is a predetermined power. A charge / discharge control method used in a charge / discharge control device for controlling the output power of the power storage device so as to fall within a range,
The charge / discharge control device comprises:
A first controller for individually controlling the power converter of the unit;
A second controller that controls a plurality of the units as a group and that controls the output power of the group via the first controller;
A third controller that distributes the charge / discharge command value of the entire power storage device used for controlling the output power of the power storage device as a group charge / discharge command value for each second controller;
With
The second controller adjusts the output power of the unit via the first controller based on the group charge / discharge command value, and controls the system power to fall within a predetermined range. The charge / discharge control method.

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