JP6005468B2 - Power conditioner, control method thereof, and DC power supply system - Google Patents

Description

  The present invention relates to a power conditioner, a control method thereof, and a DC power supply system, and more particularly to a technique for controlling the power of a plurality of storage batteries connected to the power conditioner.

  2. Description of the Related Art In recent years, development of a distributed power supply system that combines a solar battery that has little influence on the environment and power storage using a storage battery has been actively promoted from the viewpoint of protecting the global environment. The power conditioner used in such a distributed power supply system has a reverse power flow function for photovoltaic power generation, a charge / discharge function for a storage battery, and the like. Also, in a conventional distributed power supply system, DC power generated by a distributed power supply device such as a solar battery or a storage battery is converted into AC power, and the AC power is further converted into DC power in a device that consumes power. used. Therefore, DC-AC conversion and AC-DC conversion are performed, and power loss occurs every time the power is converted. Therefore, in order to reduce conversion loss, the DC power generated by the distributed power supply apparatus may be transmitted as it is without being converted into AC power and used in equipment.

  By the way, in such a distributed power supply system, it is assumed that a plurality of storage batteries are connected in parallel to the power conditioner in order to realize large-capacity power storage. Therefore, storage batteries having different storage battery characteristics and storage capacities may be connected simultaneously. Techniques have been proposed for effectively utilizing the characteristics of each other when two different power storage media are connected in parallel.

  For example, Japanese Patent Laying-Open No. 2010-41865 (Patent Document 1) discloses a charge / discharge control method for a power storage device. The power storage device is configured by connecting in parallel a power storage medium having a small change in terminal voltage during charge / discharge with a different charge / discharge behavior and a power storage medium having a large change in terminal voltage. The power storage device is provided with the charge / discharge suppression unit only between the power storage medium and the power source, in which the change in terminal voltage is small. The charge / discharge suppression unit is configured by a diode provided in the forward direction for charging, a series circuit of charge suppression resistors, a discharge suppression resistor connected in parallel with the series circuit, and a series circuit of switch bodies. ing. In the charge / discharge control method of the power storage device, control is performed such that the switch body is opened when each power storage medium connected in parallel is opened, and the switch body is closed when each power storage medium connected in parallel is discharged.

JP 2010-41865 A

  However, according to the technique of Patent Document 1, the switch provided in the charge / discharge suppression unit is opened at the time of charging, and the switch is closed at the time of discharging. Further, since a charging current flows from the electric double layer capacitor to the storage battery, it is necessary to arrange a resistor in order to prevent a large current from flowing through the storage battery. Further, the bus voltage may fluctuate greatly due to the electric double layer capacitor having a large voltage change.

  The present invention has been made to solve the above-described problems, and is a power conditioner capable of more effectively utilizing the power of a plurality of storage batteries connected to the power conditioner, and its control It is an object to provide a method and a DC power supply system.

  According to an embodiment, a power conditioner is provided that is coupled between a plurality of power storage devices including a power storage unit and a power system, and controls each power. The power conditioner includes a DC bus for transmitting DC power. The plurality of power storage units are connected in parallel to each other via a DC bus. The power conditioner further includes a power conversion unit that converts power bidirectionally between the DC bus and the power system, and a control unit that controls the power of the power storage unit of each power storage device. Based on the information indicating the relationship between the battery remaining amount and the voltage of each power storage unit, the control unit includes at least one of the plurality of power storage units other than the power storage unit having the largest voltage change with respect to the battery remaining amount within a predetermined range. Selection means for selecting a power storage unit, and connection control means for controlling connection between the selected power storage unit and the DC bus based on the remaining battery level of the selected power storage unit.

  Preferably, the control unit further includes acquisition means for acquiring information indicating a remaining battery level of the corresponding power storage unit and information indicating a relationship between the remaining battery level and the voltage from the plurality of power storage devices.

  Preferably, the connection control means, with respect to the power storage device corresponding to the selected power storage unit, when the remaining battery level of the selected power storage unit exceeds a predetermined range, the selected power storage unit and the DC bus Connect / disconnect between.

  Preferably, the predetermined range is between a first threshold value of the remaining battery level and a second threshold value smaller than the first threshold value. When the remaining battery level of the selected power storage unit is greater than the first threshold, the connection control means is configured to supply power from the DC bus to the selected power storage unit between the selected power storage unit and the DC bus. The charging path for charging the battery is cut off, and the discharging path for discharging the power from the selected power storage unit to the DC bus is connected, so that the remaining battery level of the selected power storage unit is lower than the second threshold value. If it is smaller, the charging path is connected and the discharging path is interrupted.

  Preferably, the battery pack further includes a charge / discharge current detector that detects a charge / discharge current of the power storage device. The control unit further includes current control means for controlling power conversion in the power conversion unit such that the detected charge / discharge current becomes a predetermined value.

  Preferably, the connection control unit is configured to determine the determined power storage unit and the DC bus for the power storage device corresponding to the power storage unit that is determined to have the largest voltage change with respect to the remaining battery level within the predetermined range. Connect between the two.

  According to another embodiment, a control method for a power conditioner is provided that is coupled between a plurality of power storage devices including a power storage unit and a power system, and controls each power. The power conditioner includes a DC bus for transmitting DC power, and a power converter that converts power bidirectionally between the DC bus and the power system. The plurality of power storage units are connected in parallel to each other via a DC bus. The control method of the inverter is based on the information indicating the relationship between the remaining battery level and the voltage of each power storage unit, and the power storage unit other than the power storage unit having the largest voltage change with respect to the battery remaining amount within a predetermined range among the plurality of power storage units. And selecting the at least one power storage unit, and controlling the connection between the selected power storage unit and the DC bus based on the remaining battery level of the selected power storage unit.

  According to yet another embodiment, it includes a plurality of power storage devices including a power storage unit, and a power conditioner that is coupled between the power storage device and the power system and controls each power. The power conditioner includes a DC bus for transmitting DC power. The plurality of power storage units are connected in parallel to each other via a DC bus. The power conditioner further includes a power conversion unit that converts power bidirectionally between the DC bus and the power system, and a control unit that controls the power of the power storage unit of each power storage device. Based on the information indicating the relationship between the battery remaining amount and the voltage of each power storage unit, the control unit includes at least one of the plurality of power storage units other than the power storage unit having the largest voltage change with respect to the battery remaining amount within a predetermined range. Selection means for selecting a power storage unit, and connection control means for controlling connection between the selected power storage unit and the DC bus based on the remaining battery level of the selected power storage unit.

  It becomes possible to utilize the electric power of the some storage battery connected to the power conditioner more effectively.

It is a figure which shows roughly the whole structure of the direct-current power supply system according to this Embodiment. It is a figure which shows an example of the battery residual amount-voltage curve of the some storage battery according to this Embodiment. It is a block diagram which shows the specific example of a structure of the control unit according to this Embodiment. It is the schematic which shows the structure of the bidirectional | two-way DC / AC converter in FIG. It is a figure for demonstrating charging / discharging operation | movement of the some storage battery according to this Embodiment. FIG. 6 is a state transition diagram illustrating state transition of a plurality of power storage devices in FIG. 5. It is a flowchart which shows an example of the control processing procedure performed with the power conditioner according to this Embodiment. It is a figure which shows roughly the structure of the whole DC power supply system according to the modification (the 1) of this Embodiment. It is a figure which shows an example of the battery residual amount-voltage curve of the some storage battery according to the modification (the 1) of this Embodiment. It is a figure for demonstrating the charging / discharging operation | movement of the some storage battery according to the modification (the 1) of this Embodiment. FIG. 11 is a state transition diagram illustrating a state transition of a plurality of power storage devices in FIG. 10. It is a figure which shows roughly the structure of the whole DC power supply system according to the modification (the 2) of this Embodiment. It is a figure which shows an example of the battery residual amount-voltage curve of the some storage battery according to the modification (the 2) of this Embodiment. It is a figure for demonstrating the charging / discharging operation | movement of the some storage battery according to the modification (the 2) of this Embodiment. It is a figure for demonstrating the charging / discharging operation | movement of the some storage battery according to the modification (the 2) of this Embodiment. FIG. 16 is a state transition diagram showing a state transition of a plurality of power storage devices in FIGS. 14 and 15. It is a flowchart which shows an example of the control processing procedure performed with the power conditioner according to the modification (the 2) of this Embodiment. It is a figure which shows the other circuit structure of switch SW.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<A. System configuration>
FIG. 1 is a diagram schematically showing an overall configuration of DC power supply system 1 according to the present embodiment.

  Referring to FIG. 1, a DC power supply system 1 includes a power conditioner 100, power storage devices 200A and 200B (hereinafter also collectively referred to as “power storage device 200”), a solar power generation system 800 that is a DC power source, Power system 900.

  Power conditioner 100 is connected to power system 900 to supply power to power storage device 200 or a DC load (not shown). Specifically, the power conditioner 100 supplies the power supplied from the power storage device 200, the solar power generation system 800, or the power system 900 to the DC load via the DC bus 30. The DC load is, for example, an electric device such as an air conditioner, a refrigerator, a washing machine, a television set, a lighting device, or a personal computer used at home.

  The power conditioner 100 is configured to receive AC power from the power system 900 (power purchase), and to allow power generated by the solar power generation system 800 or the like to flow backward (sell power) to the power system 900. ing. A detailed configuration of the power conditioner 100 will be described later.

  The power storage device 200 is a rechargeable power storage element, and typically includes a secondary battery such as a lithium ion battery or a nickel metal hydride battery. The power storage device 200 is configured by connecting a plurality of battery cells in series. A detailed configuration of the power storage device 200 will be described later.

  The solar power generation system 800 includes a solar cell 810 and a DC / DC converter 820. The solar cell 810 is constituted by a crystalline solar cell, a polycrystalline solar cell, a thin film solar cell, or the like. The DC / DC converter 820 is connected between the solar cell 810 and the power conditioner 100, converts the DC power received from the solar cell 810 into a voltage, and supplies it to the power conditioner 100. The DC / DC converter 820 performs control (so-called maximum power point tracking control) such that maximum power can be acquired from the solar cell 810.

  The power system 900 is typically a single-phase three-wire commercial AC power system. In the single-phase three-wire commercial AC power system, the neutral wire is grounded via a resistor, and AC200V is supplied using two wires other than the neutral wire (R-phase wire RL and T-phase wire TL). To do.

  Hereinafter, the configuration of the power storage device 200 and the power conditioner 100 will be further described.

<B. Configuration of power storage device>
Referring to FIG. 1, power storage device 200A includes a storage battery 210A, a management unit 220A, switches SW1a and SW2a, and diodes D1a and D2a. Power storage device 200B includes a storage battery 210B, a management unit 220B, switches SW1b and SW2b, and diodes D1b and D2b. Hereinafter, storage batteries 210A and 210B are “storage battery 210”, management units 220A and 220B are “management unit 220”, switches SW1a and 1b are “switch SW1”, switches SW2a and 2b are “switch SW2”, and diodes D1a and D1b are “Diode D1” and diodes D2a and D2b are also collectively referred to as “diode D2”.

  The storage battery 210 is a power storage element that can be charged and discharged as described above. The storage battery 210A is formed of a secondary battery such as an iron phosphate lithium ion battery (a lithium iron phosphate applied to the positive electrode and a graphite system applied to the negative electrode). On the other hand, the storage battery 210B is composed of a secondary battery such as a lead storage battery or a lithium ion battery other than iron phosphate.

  FIG. 2 is a diagram showing an example of a remaining battery voltage-voltage curve of a plurality of storage batteries according to the present embodiment. In FIG. 2, the horizontal axis represents the state of charge (SOC) (%) of the storage battery 210, and the vertical axis represents the voltage (V) of the storage battery 210. Correspondence with voltage) is shown. The SOC is a percentage (0 to 100%) of the current remaining capacity with respect to the full charge capacity. The storage battery 210 is used in a predetermined range of remaining battery power in order to prevent overcharge and overdischarge. Here, it is assumed that each storage battery 210 is basically used between Th1 that is the upper limit threshold of SOC and Th2 that is the lower limit threshold (that is, Th2 <SOC <Th1).

Referring to FIG. 2, the battery voltage Va of the battery 210A, in Th2 <SOC <Th1, it can be seen that stable at _{V M.} On the other hand, it can be seen that the battery voltage Vb of the storage battery 210B has a relatively large voltage change (slope) with respect to the change in the remaining battery level when Th2 <SOC <Th1. Although details will be described later, states (A) to (E) shown in FIG. 2 correspond to states (A) to (E) in FIG.

  Referring again to FIG. 1, management unit 220 manages the remaining battery level of storage battery 210. The management unit 220 includes storage means such as a memory (not shown), and stores information related to the remaining battery level of the storage battery 210 (hereinafter also referred to as “battery related information”) in the memory. The battery-related information is information indicating the relationship between the remaining battery level and voltage of the storage battery 210 (for example, the remaining battery voltage-voltage curve data shown in FIG. 2), and information indicating the current remaining battery level of the storage battery 210. . Management unit 220 also stores information for specifying power storage device 200 in the memory. As information which specifies the electrical storage apparatus 200, the kind of storage battery 210, a manufacturing number, etc. may be sufficient, for example. These may be stored in advance at the time of shipment, or may be input and stored after that.

  The management unit 220 is configured to be able to perform power line communication (PLC) using the DC bus 30 with the control unit 10 described later. Alternatively, the management unit 220 may be configured to communicate with the control unit 10 via a wireless or wired dedicated line. In one aspect, management unit 220 associates information identifying power storage device 200 with battery-related information and transmits the information to control unit 10. The transmission timing may be a so-called push type, which may be a pre-defined time interval or a timing specified on the side after a predetermined time after the power is turned on, or a so-called pull type. The timing at which the request is received from the control unit 10 may be used.

  In another aspect, management unit 220 controls opening and closing of switches SW <b> 1 and SW <b> 2 based on a control signal received from control unit 10. Here, the switch SW1 is provided between the storage battery 210 and the diode D1 that flows current from the DC bus 30 side to the storage battery 210 side. The switch SW2 is provided between the storage battery 210 and the diode D2 that flows current from the storage battery 210 side to the DC bus 30 side. In other words, the management unit 220 opens or closes the switch SW1, thereby connecting or blocking a charging path for charging the storage battery 210 with power from the DC bus 30. The management unit 220 opens or closes the switch SW2, thereby connecting or blocking a discharge path for discharging power from the storage battery 210 to the DC bus 30.

  The management unit 220 may have a hardware configuration such as a circuit, or may include a CPU (not shown) and a function realized by the CPU when the CPU executes a program stored in the memory, that is, a software configuration. Also good.

<C. Configuration of the inverter>
(C1. Overall configuration)
The power conditioner 100 is collectively referred to as a control unit 10, a bidirectional DC / AC converter 20, a DC bus 30, a connection terminal 40, and connection terminals 42A, 42B, and 42C (hereinafter also referred to as “connection terminal 42”). ) And current sensors 50 and 52.

  The control unit 10 controls the electric power of the storage battery 210 in a certain situation. Specifically, the control unit 10 is configured to be communicable with the power storage device 200, and controls connection between the storage battery 210 and the DC bus 30 based on battery-related information acquired from the power storage device 200. In another aspect, control unit 10 controls charging / discharging of storage battery 210 by instructing the output result from current sensor 50 and bidirectional DC / AC converter 20. Details of the configuration of the control unit 10 will be described later.

  The DC bus 30 is a power line for transmitting DC power, and includes a positive bus PL and a negative bus NL that are power line pairs. A bidirectional DC / AC converter 20 and connection terminals 40 and 42 are connected to the DC bus 30.

  The connection terminals 40 and 42 constitute a “connection unit” for electrically connecting a DC power source provided outside the power conditioner 100 to the DC bus 30. In the DC power supply system 1, the connection terminal 40 electrically connects the photovoltaic power generation system 800 to the DC bus 30. By connecting the solar power generation system 800 to the connection terminal 40, the power generated by the solar battery 810 is supplied to the DC bus 30. Connection terminal 42 connects power storage device 200 to DC bus 30. By connecting power storage device 200 to connection terminal 42, power is transferred between DC bus 30 and power storage device 200. In the example of FIG. 1, power storage devices 200A and 200B are coupled to connection terminals 42A and 42B, respectively. At this time, power storage devices 200 </ b> A and 200 </ b> B are connected in parallel to each other via DC bus 30. Further, the power conditioner 100 may have a connection terminal 44 for electrically connecting a DC device to the DC bus 30.

  Bidirectional DC / AC converter 20 is connected between DC bus 30 and power system 900. Bidirectional DC / AC converter 20 converts the DC power received from DC bus 30 into AC power and supplies it to power system 900. The bidirectional DC / AC converter 20 converts AC power received from the power system 900 into DC power and supplies it to the DC bus 30. As described above, the power conditioner 100 is configured to be able to buy grid power from a power company or the like (power purchase) and to sell surplus power to the power company or the like (power sale).

  In FIG. 1, for current flowing in the bidirectional DC / AC converter 20 (hereinafter also referred to as “self-path current”) Iinv, the self-path current at the time of power purchase is Ibuy, and the self-path current at the time of power sale is Icell. Is written. The values of the currents Isel and Ibuy can be freely set by the user of the DC power supply system 1 or the electric power company.

  In addition, the bidirectional DC / AC converter 20 receives the DC bus 30 and the electric power in response to a request for the electric power sold or purchased from an electric power company or an instruction from the control unit 10 based on the remaining battery capacity of the storage battery 210 or the like. It controls the power exchanged between the systems 900. Details of the configuration of the bidirectional DC / AC converter 20 will be described later.

  Current sensor 50 detects charge / discharge current (battery current) Ib input / output to / from storage battery 210 included in power storage device 200, and outputs the detected value to control unit 10. The current sensor 50 detects the charging current Ich to the storage battery 210 as a positive battery current Ib, and detects the discharge current Idc from the storage battery 210 as a negative battery current Ib.

  The current sensor 52 detects a self-path current Iinv that is a current of AC power exchanged between the bidirectional DC / AC converter 20 (more specifically, a bidirectional inverter described later) and the power system 900. The detection result is output to the control unit 10.

(C2. Configuration of control unit)
Next, the configuration of the control unit 10 will be described.

  FIG. 3 is a block diagram showing a specific example of the configuration of the control unit 10 according to the present embodiment.

  Referring to FIG. 3, input unit 11, storage unit 12, information acquisition unit 13, selection unit 14, connection control unit 15, and current control unit 16 are included.

  The input unit 11 corresponds to a button for receiving an operation from the user. The input unit 11 may accept a user operation from a user interface screen displayed on a monitor (not shown).

  The storage unit 12 stores various data (or programs) necessary for control executed by the control unit 10. Typically, the storage unit 12 includes a RAM (Random Access Memory), a ROM (Read-Only Memory), and the like.

  The information acquisition unit 13 acquires the battery-related information described above from each power storage device 200 (management unit 220). The information acquisition unit 13 is configured to be able to perform power line communication using the DC bus 30 with each power storage device 200. For example, when the power storage device 200 is connected to the connection terminal 42, the information acquisition unit 13 acquires the above-described battery-related information by performing communication with the power storage device 200. The information acquisition unit 13 can also grasp the number of power storage devices 200 connected to the connection terminal 42 by performing communication with the power storage device 200.

  Note that the information acquisition unit 13 may be configured to communicate with a DC power source wirelessly. Alternatively, each of the connection terminals 42 may be configured by a general-purpose wired communication connector and configured to perform communication using the wired line. For example, communication is performed using a method such as RS485 or CAN.

  Based on the information indicating the relationship between the remaining battery level and the voltage of each storage battery 210 acquired by the information acquisition unit 13, the selection unit 14 changes the voltage with respect to the remaining battery level within a predetermined range among the plurality of storage batteries 210. Select at least one storage battery other than the storage battery having the largest value. More specifically, the selection unit 14 calculates, for each of the plurality of storage batteries 210, the slope of the voltage with respect to the remaining battery capacity in the predetermined range, and selects at least one storage battery 210 other than the storage battery having the largest slope. To do.

  Here, referring to FIG. 2 as an example, in the predetermined range (Th2 <SOC <Th1), the selection unit 14 determines that the storage battery 210B of the storage batteries 210A and 210B has a voltage relative to the remaining battery capacity rather than the storage battery 210A. Judge that the change is large. Then, the selection unit 14 selects the storage battery 210 </ b> A and outputs the selection result to the connection control unit 15. For example, when the three power storage devices 200 are connected to the power conditioner 100, the selection unit 14 is a storage battery other than the storage battery having the largest inclination in the predetermined range among the corresponding three storage batteries 210. Select two (remaining) storage batteries.

  The connection control unit 15 controls the connection between the selected storage battery 210 and the DC bus 30 based on the remaining battery level of the selected storage battery 210. More specifically, the connection control unit 15 is selected for the power storage device 200 corresponding to the selected storage battery 210 when the remaining battery level of the selected storage battery 210 exceeds the predetermined range. The storage battery 210 and the DC bus 30 are connected / disconnected. The connection control unit 15 transmits the control signal to the power storage device 200 (management unit 220), thereby causing the above control to be executed.

  Referring to FIG. 2 as an example, the connection control unit 15 directs the storage battery 210A to DC between the storage battery 210A and the DC bus 30 when the remaining battery capacity of the selected storage battery 210A is larger than Th1. The charging path for charging the power from the bus 30 is interrupted (the switch SW1a is turned off), and the discharging path for discharging the power from the storage battery 210A to the DC bus 30 is connected (the SW2a is turned on). In addition, when the battery remaining amount of the storage battery 210A is smaller than Th2, the connection control unit 15 connects the charging path (switch SW1a is turned on) and blocks the discharging path (SW2a is turned off).

  The current control unit 16 controls power conversion in the bidirectional DC / AC converter 20 so that the charge / discharge current (battery current) Ib detected by the current sensor 50 becomes a control target value. Further, the current control unit 16 controls power conversion in the bidirectional DC / AC converter 20 so that the self-path current Iinv detected by the current sensor 52 becomes a control target value.

  The control target values (the self-path current target value Iinv * of the self-path current Iinv and the battery current target value Ib * of the battery current Ib) vary depending on, for example, the date and time or the remaining battery level (SOC) of the storage battery 210. And can be stored in the storage unit 12 in advance. The battery current target value Ib * includes a current target value Ich * of the charging current Ich and a current target value Idc * of the discharge current Idc. The own path current target value Iinv * includes a current target value Isel * of the own path current Isel at the time of power sale and a current target value Ibuy * of the own path current Ibuy at the time of power purchase.

  The current control unit 16 may determine the control target value based on the date and time and the remaining battery level of the storage battery 210 acquired by the information acquisition unit 13 or may be determined by an instruction from the user via the input unit 11. Also good. For example, the current control unit 16 determines that the remaining battery level is equal to or greater than a certain value (there is surplus power) so that the charging current flows when the remaining battery level of the storage battery 210 becomes less than a certain value (no surplus power). ), The control target value of Ib is determined so that the discharge current flows. Then, the current control unit 16 transmits a control signal to the bidirectional DC / AC converter 20 so that the battery current Ib and the self-path current Iinv described above become control target values.

(C3. Configuration of bidirectional DC / AC converter)
Next, the configuration of the bidirectional DC / AC converter 20 will be described.

FIG. 4 is a schematic diagram showing the configuration of the bidirectional DC / AC converter 20 in FIG.
Referring to FIG. 4, bidirectional DC / AC converter 20 includes a bidirectional inverter 21, interconnection reactors 22 and 23, a voltage sensor 25, and a control unit 26.

  The bidirectional inverter 21 converts the DC power received from the DC bus 30 into AC power and outputs the AC power to the power system 900 according to the switching control signals S1 to S4 from the control unit 26 at the time of selling power. Bidirectional inverter 21 converts AC power received from power system 900 into DC power and outputs it to DC bus 30 according to switching control signals S <b> 1 to S <b> 4 from control unit 26 during power purchase.

  Specifically, bidirectional inverter 21 includes transistors Q1 to Q4, which are switching elements, and diodes D1 to D4. Transistors Q1 and Q2 are connected in series between positive bus PL and negative bus NL constituting DC bus 30. An intermediate point between transistors Q1 and Q2 is connected to R-phase line RL. Interconnection reactor 22 is connected to R-phase line RL.

  Transistors Q3 and Q4 are connected in series between positive bus PL and negative bus NL. An intermediate point between transistors Q3 and Q4 is connected to T-phase line TL. Interconnection reactor 23 is connected to T-phase line TL. Between the collectors and emitters of the transistors Q1 to Q4, diodes D1 to D4 that flow current from the emitter side to the collector side are respectively connected. Transistors Q1-Q4 and diodes D1-D4 constitute a full bridge circuit.

  As the transistors Q1 to Q4, for example, IGBTs (Insulated Gate Bipolar Transistors) can be used. Alternatively, a power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) may be used.

  Voltage sensor 25 is connected between positive bus PL and negative bus SL, detects voltage value Vdc of power transferred between bidirectional inverter 21 and power system 900, and outputs the detection result to control unit 26. Output.

  Based on the voltage Vdc received from the voltage sensor 25, the control signal transmitted from the control unit 10, the battery current Ib, and the own path current Iinv, the control unit 26 determines whether the battery current Ib and the own path current Iinv are control targets. Switching control signals S1 to S4 for controlling on / off of the transistors Q1 to Q4 are generated so as to have a value, and the bidirectional inverter 21 is controlled.

  For example, when receiving a control signal that causes a charging current to flow from the control unit 10 (receives a positive battery current target value Ib *), the control unit 26 changes the battery current Ib in the positive direction (charging direction). (Battery current Ib is increased). When the control unit 26 receives a control signal from the control unit 10 so as to allow the discharge current to flow (receives a negative battery current target value Ib *), the control unit 26 changes the battery current Ib in the negative direction (discharge direction). (Battery current Ib is reduced). That is, the control unit 26 generates the switching control signals S1 to S4 based on the current deviation between the battery current Ib and the battery current target value Ib *.

<D. Control method>
Next, a control method for controlling the power of the storage battery 210 by the power conditioner 100 opening and closing the switches SW1 and SW2 according to the SOC value of the storage battery 210 will be described with reference to the drawings.

(D1. Charge / discharge operation)
Here, with reference to FIG. 2 and the following FIGS. 5 and 6, how charge / discharge of the storage batteries 210 </ b> A and 210 </ b> B is changed by the control of the power conditioner 100 will be described. Here, in order to effectively use the storage battery 210, it is assumed that any storage battery 210 is used between Th2 <SOC <Th1.

  FIG. 5 is a diagram for describing charging / discharging operations of a plurality of storage batteries 210 according to the present embodiment. 5 does not illustrate a part of the configuration of the power conditioner 100 and the power storage device 200 for ease of explanation, it is assumed that these are configured as shown in FIG. 1 described above.

FIG. 6 is a state transition diagram showing a state transition of the plurality of power storage devices 200 in FIG.
Note that states (A) to (E) in FIG. 6 correspond to states (A) to (E) in FIGS. 2 and 5.

  Here, referring to FIGS. 2, 5, and 6, a state in which switches SW <b> 1 a, 1 b and SW <b> 2 a, 2 b are turned on for power storage devices 200 </ b> A and 200 </ b> B by power conditioner 100 (FIGS. 2, 5, 6). The state (A)) will be described. As described above, power conditioner 100 communicates with power storage devices 200 </ b> A and 200 </ b> B to acquire respective battery remaining amount-voltage curve data, and the storage battery has a small voltage change with respect to the remaining battery amount in Th <b> 2 <SOC <Th <b> 1. The switches SW1a and 2a of 210A are controlled.

Referring to FIG. 5, in the state (A), the charging path and discharging path between storage batteries 210A and 210B and DC bus 30 are both connected. Therefore, in state (A), voltage Vdc of DC bus 30 is equal to battery voltage Va and battery voltage Vb. Actually, a slight voltage difference occurs between the DC bus voltage Vdc and the battery voltages Va and Vb due to the diodes D1 and D2 and the wiring impedance, but in this embodiment, it is assumed to be negligibly small. Further, since the battery 210A and 210B are used between the Th2 <SOC <Th1, referring to FIG. 2, the voltage relationship in the state (A) becomes _{Vdc = Va = Vb = V M} .

In the state (A), at the time of charge control in which the power conditioner 100 flows the charging current Ich, only the storage battery 210A is charged (arrow Rch1). Further, during the discharge control in which the power conditioner 100 allows the discharge current Idc to flow, power is discharged only from the storage battery 210A (arrow Rdc1). In other words, the storage battery 210A is charged / discharged with Th2 <SOC _A <Th1, but the storage battery 210B is not charged / discharged because it is fixed to SOC _B = Cr (that is, in this state, the storage battery 210B is Cannot be used effectively).

Next, the power conditioner 100 performs charge control from the state (A), and turns off SW1a when the storage battery 210A is charged with power and SOC _A > Th1. And if the power conditioner 100 further continues charge control, it will change from a state (A) to a state (B) (corresponding to (1) in FIG. 6). In the state (B), in the storage battery 210A, the charging path is interrupted and the discharging path is connected. In storage battery 210B, both the charging path and the discharging path are connected. Referring to FIG. 2, the voltage relationship in a state (B) of _{Vdc = Vb> Va = V M} . At this time, the DC bus voltage Vdc increases or decreases while maintaining a state equal to Vb.

In the state (B), during the charging control by the power conditioner 100, only the storage battery 210B is charged with power (arrow Rch2). Further, during discharge control by the power conditioner 100, power is discharged only from the storage battery 210B (arrow Rdc2). That is, power is not charged in the storage battery 210A (because the switch SW1a is OFF), and power is not discharged from the storage battery 210A (because the discharge path is connected, but Vdc> Va). In contrast, the storage battery 210B is charged and discharged with Cr <SOC _B <Th1.

Next, the power conditioner 100 performs charging control from the state (B), and when the storage battery 210B is charged with power and SOC _B > Th1, SOC _B reaches the upper limit, and charging cannot be performed any more. Stop control. And if the power conditioner 100 starts discharge control, electric power will be discharged from the storage battery 210B. When the power conditioner 100 discharges the storage battery 210B until SOC _B = Cr, the state transitions from the state (B) to the state (C) (corresponding to (2) in FIG. 6). In the state (C), the connection states of the charging paths and discharging paths of the storage batteries 210A and 210B are the same as in the state (B). However, referring to FIG. 2, because the voltage relationship becomes _{Vdc = Va = Vb = V M} , charge and discharge operations of the battery 210A and 210B are different. In addition, the power conditioner 100 starts discharge control, and when the electric power is discharged from the storage battery 210B and SOC _B <Th1, the charge control is started even if the state (C) is not changed. Thus, the storage battery 210B can be charged with electric power.

In the state (C), at the time of charging control by the power conditioner 100, only the storage battery 210B is charged with power (arrow Rch3). Then, <become SOC _B, the voltage relationship Vdc = Vb> from _SOC B = Cr Cr changes to Va = _{V M,} a transition from the state (C) to the state (B) (in (3) in FIG. 6 Correspondence). Further, during discharge control by the power conditioner 100, power is discharged only from the storage battery 210A (arrow Rdc3). In other words, discharge is preferentially from battery 210A since the power to the storage battery 210A not charged (because the switch SW1a is OFF), a power from the battery 210B is not discharged _{(Vdc = Va = Vb = V} M For).

Next, the power conditioner 100 performs discharge control from the state (C), and when the power is discharged from the storage battery 210A and SOC _A <Th3 is turned ON, the SW1a is turned on, and then the state (C) is changed from the state (C) to the state (A ) (Corresponding to (4) in FIG. 6). Th3 is Th2 <Th3 <Th1.

Next, the power conditioner 100 performs discharge control from the state (A), and turns off SW2a when power is discharged from the storage battery 210A and SOC _A <Th2. And if the power conditioner 100 further continues discharge control, it will change to a state (D) from a state (A) (corresponding to (5) of Drawing 6). In state (D), in storage battery 210A, the charging path is connected and the discharging path is blocked. In storage battery 210B, both the charging path and the discharging path are connected. Referring to FIG. 2, the voltage relationship in a state (D) becomes _{Vdc = Vb <Va = V M} . The DC bus voltage Vdc increases / decreases while maintaining a state equal to Vb.

In the state (D), at the time of charging control by the power conditioner 100, only the storage battery 210B is charged with power (arrow Rch4). Further, during discharge control by the power conditioner 100, power is discharged only from the storage battery 210B (arrow Rdc4). That is, power is not charged in the storage battery 210A (because the charging path is connected but Vdc <Va), and power is not discharged from the storage battery 210A (because the switch SW2a is turned off). On the other hand, the storage battery 210B is charged / discharged with Th2 <SOC _B <Cr.

Next, the power conditioner 100 performs the discharge control from the state (D). When the electric power is discharged from the storage battery 210B and SOC _B <Th2, the SOC _B reaches the lower limit, and no further discharge is possible. Stop control. And when the power conditioner 100 starts charge control, electric power will be charged to the storage battery 210B. When power conditioner 100 charges storage battery 210B until SOC _B = Cr, the state (D) transitions to state (E) (corresponding to (6) in FIG. 6). In the state (E), the connection state of the charging path and the discharging path of the storage batteries 210A and 210B is the same as that in the state (D). However, referring to FIG. 2, because the voltage relationship becomes _{Vdc = Va = Vb = V M} , charge and discharge operations of the battery 210A and 210B are different. In addition, the power conditioner 100 starts charge control, and when the storage battery 210B is charged with power and SOC _B > Th2, the discharge control is started even if the state (E) is not changed. Thus, power can be discharged from the storage battery 210B.

In the state (E), at the time of discharge control by the power conditioner 100, power is discharged only from the storage battery 210B (arrow Rdc5). Then, consists _SOC B = Cr in _SOC B <Cr, the voltage relationship changes on _{Vdc = Vb <Va = V M} , a transition from the state (E) to the state (D) ((7) in FIG. 6 Correspondence). Further, during charging control by the power conditioner 100, only the storage battery 210A is charged with power (arrow Rch5). That is, charging of the battery 210A has priority because the power from the battery 210A not discharged (the switch SW2a is OFF), the power to the battery 210B is not charged _{(Vdc = Va = Vb = V} M For).

Then, the power conditioner 100 performs charge control from the state (E), and when the power is charged in the storage battery 210A and SOC _A > Th4 is turned ON, when the SW2a is turned on, the state (E) is changed from the state (E) to the state (A). (Corresponding to (8) in FIG. 6). Th4 is Th2 <Th4 <Th1.

(D2. Processing procedure)
Next, a control processing procedure executed in power conditioner 100 according to the present embodiment will be described.

  FIG. 7 is a flowchart showing an example of a control processing procedure executed in power conditioner 100 according to the present embodiment. Each step shown in FIG. 7 is assumed to be realized by software processing and / or hardware processing by the control unit 10 included in the power conditioner 100. It is assumed that the initial state of power storage devices 200A and 200B is the state (A) shown in FIGS.

  Referring to FIG. 7, control unit 10 obtains battery-related information by communicating with power storage devices 200A and 200B (step S1). More specifically, the control unit 10 acquires information indicating the remaining battery level-voltage curve data of the storage batteries 210A and 210B and the current remaining battery level. Note that information indicating the remaining battery level is acquired by the control unit 10 at regular control cycles. Thereby, the control unit 10 can grasp | ascertain the battery residual amount of storage battery 210A, 210B in real time.

  Next, the control unit 10 calculates the slope of the voltage with respect to the remaining battery level in a predetermined range based on the remaining battery level-voltage curve data, and selects at least one storage battery 210 other than the storage battery having the largest slope. (Step S2). More specifically, the control unit 10 selects the storage battery 210A because the inclination of the storage battery 210A is smaller than that of the storage battery 210B when Th2 <SOC <Th1.

  Next, the control unit 10 determines whether or not the storage battery 210 is charged (step S3). The control unit 10 makes the determination based on the date and time, the SOC of the storage battery 210, and the like. When not charging (in the case of NO in step S3), the control unit 10 determines whether or not to discharge power from the storage battery 210 (step S19). The control unit 10 makes the determination based on the date and time, the SOC of the storage battery 210, and the like. When not discharging (that is, when neither charging nor discharging) (NO in step S19), the control unit 10 repeats the processing from step S1. When discharging (in the case of YES in step S19), the control unit 10 executes the processing from step S20. Processing from step S20 will be described later.

  When charging (in the case of YES in step S3), the control unit 10 executes charge control (step S4). More specifically, the control unit 10 transmits a control signal to the bidirectional DC / AC converter 20 so that the charging current becomes the control target value. Based on the control signal, the bidirectional DC / AC converter 20 changes the battery current Ib in the positive direction (charging direction) so as to become the control target value.

Next, the control unit 10 determines whether or not SOC _A is larger than Th1 (step S6). If SOC _A is not greater than Th1 (NO in step S6), control unit 10 executes processing from step S12 described later. On the other hand, when SOC _A is larger than Th1 (YES in step S6), control unit 10 controls to turn off switch SW1a corresponding to the charging path of selected storage battery 210A ( Step S8). More specifically, control unit 10 transmits a control signal to power storage device 200A (management unit 220A) to turn off switch SW1a.

Next, the control unit 10 determines whether or not SOC _B is greater than Th1 (step S12). When SOC _B is not greater than Th1 (NO in step S12), control unit 10 executes processing from step S16 described later. On the other hand, when SOC _B is larger than Th1 (YES in step S12), control unit 10 stops the charging control (step S14). More specifically, the control unit 10 transmits a control signal for stopping the charging control to the bidirectional DC / AC converter 20. The bidirectional DC / AC converter 20 stops charging control based on the control signal.

Next, the control unit 10 determines whether or not SOC _A is larger than Th4 (step S16). If SOC _A is not greater than Th4 (NO in step S16), the processing from step S1 is repeated. On the other hand, when SOC _A is larger than Th4 (YES in step S16), control unit 10 determines whether or not switch SW2a is OFF (step S17). If switch SW2a is not OFF (ON) (NO in step S17), the processing from step S1 is repeated. On the other hand, when the switch SW2a is OFF (YES in step S17), control is performed to turn on the switch SW2a (step S18). And the control unit 10 repeats the process from step S1.

Next, the process after step S20 is demonstrated.
When the control unit 10 discharges the storage battery 210 (YES in step S19), the control unit 10 executes discharge control (step S20). More specifically, the control unit 10 transmits a control signal to the bidirectional DC / AC converter 20 so that the discharge current becomes the control target value. Based on the control signal, the bidirectional DC / AC converter 20 changes the battery current Ib in the negative direction (discharge direction) so as to become the control target value.

Next, the control unit 10 determines whether or not SOC _A is smaller than Th2 (step S22). If SOC _A is not smaller than Th1 (NO in step S22), processing from step S28 described later is executed. On the other hand, when SOC _A is smaller than Th2 (YES in step S22), control unit 10 performs control so that switch SW2a is turned off (step S22).

Next, the control unit 10 determines whether or not SOC _B is smaller than Th2 (step S28). If SOC _B is not smaller than Th2 (NO in step S28), processing from step S32 described later is executed. On the other hand, when SOC _B is smaller than Th2 (YES in step S28), control unit 10 stops the discharge control. (Step S30). More specifically, the control unit 10 transmits a control signal for stopping the discharge control to the bidirectional DC / AC converter 20. The bidirectional DC / AC converter 20 stops the discharge control based on the control signal.

Next, the control unit 10 determines whether or not SOC _A is smaller than Th3 (step S32). If SOC _A is not smaller than Th3 (NO in step S32), the processing from step S1 is repeated. On the other hand, when SOC _A is smaller than Th3 (YES in step S32), control unit 10 determines whether or not switch SW1a is OFF (step S33). If switch SW1a is not OFF (ON) (NO in step S33), the processing from step S1 is repeated. On the other hand, when the switch SW1a is OFF (YES in step S33), control is performed to turn on the switch SW1a (step S34). And the control unit 10 repeats the process from step S1.

In the above description, the control unit 10 may control the switch SW1b to be turned off instead of stopping the charging control in step S14. In this case, after step S34 of the discharge-side loop, a process for controlling the switch SW1b to be turned on is added on condition that SOC _B is smaller than Th1.

Further, the control unit 10 may perform control so that the switch SW2b is turned off instead of stopping the discharge control in step S30. In this case, after step S18 of the charging-side loop, a process for controlling the switch SW2b to be turned on is added on condition that SOC _B is greater than Th2.

<E. Modification (Part 1)>
Here, DC power supply system 2 which is a modification (part 1) of DC power supply system 1 according to the present embodiment will be described.

(E1. Overall configuration)
FIG. 8 is a diagram schematically showing an overall configuration of DC power supply system 2 according to a modification (No. 1) of the present embodiment.

  Referring to FIG. 1, DC power supply system 1 includes a power conditioner 100, power storage devices 200B and 200C, a solar power generation system 800 that is a DC power source, and a power system 900. That is, the DC power supply system 2 is basically the same except that the DC power supply system 1 is configured by connecting the power storage device 200C to the connection terminal 42A instead of the power storage device 200A. Therefore, detailed description of the same configuration and function as those of DC power supply system 1 will not be repeated.

(E2. Configuration of power storage device)
Power storage device 200C includes a storage battery 210C, a management unit 220C, switches SW1c and SW2c, and diodes D1c and D2c. The management unit 220C, the switches SW1c and SW2c, and the diodes D1c and D2c are <B. Since it is basically the same as the function of power storage device 200 described in “Configuration of power storage device>, detailed description thereof will not be repeated.

  The storage battery 210C is configured by a secondary battery such as a lead storage battery or a lithium ion battery other than iron phosphate. That is, the storage battery 210C is the same type of secondary battery as the storage battery 210B.

  FIG. 9 is a diagram showing an example of the remaining battery voltage-voltage curve of the plurality of storage batteries 210 according to the modification (No. 1) of the present embodiment.

  Referring to FIG. 9, it can be seen that storage battery 210B and storage battery 210C both have a relatively large voltage change (slope) with respect to the remaining battery capacity when Th2 <SOC <Th1. More specifically, in Th2 <SOC <Th1, the voltage change of the storage battery 210C is larger than that of the storage battery 210B.

(E3. Charge / discharge operation)
For the configuration of the inverter 100, <C. Since it is basically the same as that described in the configuration of the inverter>, detailed description thereof will not be repeated.

  Here, with reference to FIG. 9 and the following FIGS. 10 and 11, how the charging / discharging of the storage batteries 210 </ b> B and 210 </ b> C is changed by the control of the power conditioner 100 will be described. Here, in order to effectively use the storage battery 210, it is assumed that any storage battery 210 is used between Th2 <SOC <Th1.

  FIG. 10 is a diagram for explaining the charging / discharging operation of the plurality of storage batteries 210 according to the modification (No. 1) of the present embodiment. In FIG. 10, for ease of explanation, part of the configuration of the power conditioner 100 and the power storage device 200 is not shown, but these are configured as shown in FIG. 8 described above.

  FIG. 11 is a state transition diagram showing a state transition of the plurality of power storage devices 200 in FIG. Note that states (A) to (E) in FIG. 11 correspond to states (A) to (E) in FIGS. 9 and 10.

  9, 10, and 11, power conditioner 100 turns on switches SW <b> 1 b and 1 c and SW <b> 2 b and 2 c for power storage devices 200 </ b> B and 200 </ b> C, respectively (states in FIGS. 9, 10, and 11 ( A)) will be described. Note that the power conditioner 100 communicates with the power storage devices 200B and 200C to acquire the respective battery remaining amount-voltage curve data, and switches the storage battery 210B with a small voltage change with respect to the remaining battery amount in Th2 <SOC <Th1. SW1b and 2b are controlled.

Referring to FIG. 10, in the state (A), the charging path and discharging path between storage batteries 210B and 210C and DC bus 30 are both connected. Therefore, in the state (A), the DC bus voltage Vdc is equal to the battery voltage Vb and the battery voltage Vc. Moreover, since the storage battery 210 is used between Th2 <SOC <Th1, referring to FIG. 9, the voltage relationship in the state (A) is V _L <Vdc = Vb = Vc <V _H.

In the state (A), at the time of charging control by the power conditioner 100, the storage batteries 210B and 210C are charged with power (arrows Rch11 and Rch12). Further, at the time of discharge control by the power conditioner 100, power is discharged from the storage batteries 210B and 210C (arrows Rdc11, Rdc12). In other words, battery 210B and 210C _are charged and discharged while satisfying the _{V L <Vb = Vc <V} H.

Next, power conditioner 100 performs charge control from state (A), and turns off SW1b when power is charged in storage batteries 210B and 210C and SOC _B > Th1. And if the power conditioner 100 further continues charge control, it will change from a state (A) to a state (B) (corresponding to (1) in FIG. 11). In the state (B), in the storage battery 210B, the charging path is interrupted and the discharging path is connected. In storage battery 210C, both the charging path and the discharging path are connected. Referring to FIG. 9, the voltage relationship in a state (B) of _{Vdc = Vc> Vb = V H} . The DC bus voltage Vdc increases or decreases while maintaining a state equal to Vc.

In the state (B), at the time of charging control by the power conditioner 100, only the storage battery 210C is charged with power (arrow Rch13). Further, during the discharge control by the power conditioner 100, power is discharged only from the storage battery 210C (arrow Rdc13 in FIG. 10). That is, power is not charged in storage battery 210B (because switch SW1b is OFF), and power is not discharged from storage battery 210B (since Vdc> Vb). In contrast, the storage battery 210C is charged and discharged while satisfying V _H <Vc = Vdc.

Next, the power conditioner 100 performs charge control from the state (B). When the storage battery 210C is charged with power and SOC _C > Th1, the SOC _C reaches the upper limit, and charging cannot be performed any more. Stop control. And when the power conditioner 100 starts discharge control, electric power will be discharged from the storage battery 210C. When the power conditioner 100 discharges the storage battery 210C until SOC _C = Th5 (Vc = Vb = V _H ), the state (B) changes to the state (C) (corresponding to (2) in FIG. 11). . In the state (C), the connection states of the charging and discharging paths of the storage batteries 210B and 210C are the same as in the state (B). However, referring to FIG. 9, the voltage relationship becomes _{Vdc = Vb = Vc = V H} , charging and discharging operations are different. In addition, the power conditioner 100 starts discharge control, and when electric power is discharged from the storage battery 210C and SOC _C <Th1, the charge control is started even if the state (C) is not changed. Thereby, electric power can be charged to the storage battery 210C.

In the state (C), only the storage battery 210C is charged during the charge control by the power conditioner 100 (arrow Rch14). Then, SOC _C = Th5 changes to Th5 <SOC _C , the voltage relationship changes from Vdc = Vc> Vb = V _H , and the state (C) changes to the state (B). Further, at the time of discharge control by the power conditioner 100, power is discharged from the storage batteries 210B and 210C while satisfying Vb = Vc (arrows Rdc14, Rdc15). At this time, power is not charged in the storage battery 210B (because the switch SW1b is OFF).

Next, the power conditioner 100 performs the discharge control from the state (C), and when the power is discharged from the storage batteries 210B and 210C and the SOC _B <Th3 ′ is turned ON, the SW1b is turned on. Transition to the state (A) (corresponding to (4) in FIG. 11). Th3 ′ is Th2 <Th3 ′ <Th1.

Next, power conditioner 100 performs discharge control from state (A), and turns off SW2b when power is discharged from storage batteries 210B and 210C and SOC _B <Th2. And if the power conditioner 100 further continues discharge control, it will change to a state (D) from a state (A) (corresponding to (5) of Drawing 11). In the state (D), in the storage battery 210B, the charging path is connected and the discharging path is blocked. In storage battery 210C, both the charging path and the discharging path are connected. Referring to FIG. 9, the voltage relationship in the state (D) is Vdc = Vc <Vb = V _L. The DC bus voltage Vdc increases or decreases while maintaining a state equal to Vc.

In the state (D), at the time of charging control by the power conditioner 100, only the storage battery 210C is charged (arrow Rch16). Further, during discharge control by the power conditioner 100, power is discharged only from the storage battery 210C (arrow Rdc16). That is, power is not charged in storage battery 210B (since Vdc <Vb), and power is not discharged from storage battery 210B (since switch SW2b is turned off). On the other hand, the storage battery 210C is charged and discharged while satisfying Vc < _VL .

Next, the power conditioner 100 performs the discharge control from the state (D). When the power is discharged from the storage battery 210C and SOC _C <Th2, the SOC _C reaches the lower limit, and no further discharge is possible. Stop control. And when the power conditioner 100 starts charge control, electric power will be charged to the storage battery 210C. When power conditioner 100 charges storage battery 210C until SOC _C = Th6 (Vc = Vb = V _L ), transition from state (D) to state (E) (corresponding to (6) in FIG. 11) . In the state (E), the connection state of the charging path and discharging path of the storage batteries 210B and 210C is the same as in the state (D). However, referring to FIG. 9, since the voltage relationship is Vdc = Vb = Vc = _VL , the flow of charge / discharge current is different. In addition, the power conditioner 100 starts charge control, and when the storage battery 210C is charged with electric power and SOC _C > Th2, the discharge control is started even if the state (E) is not changed. Thus, electric power can be discharged from the storage battery 210C.

In the state (E), during the discharge control by the power conditioner 100, power is discharged only from the storage battery 210C (because the switch SW2a is OFF) (arrow Rdc17). At this time, SOC _C = Th6 changes to Th6 <SOC _C , and the voltage relationship changes from Vdc = Vc <Vb = V _L to transition from the state (E) to the state (D) ((7) in FIG. 11). Corresponding). Further, during charging control by the power conditioner 100, the storage batteries 210B and 210C are charged with electric power (arrows Rch17 and Rch18).

Next, when the power conditioner 100 performs charge control from the state (E) and turns on the SW2b when the storage batteries 210B and 210C are charged with SOC _B > Th4 ′, the power conditioner 100 starts from the state (E). Transition to state (A). Note that Th4 ′ is Th2 <Th4 ′ <Th1.

It should be noted that the control processing procedure executed by power conditioner 100 according to the modification (No. 1) of the present embodiment can be considered basically the same as the processing procedure in FIG. That is, the control processing procedure executed by the power conditioner 100 according to the modified example (Part 1) is SOC _A , SOC _B , SW1a, SW2a, Th3, Th4 in the flowchart in FIG. 7, and SOC _B , SOC _C , SW1b, respectively. , SW2b, Th3 ′, and Th4 ′. Therefore, detailed description thereof will not be repeated.

<F. Modification (Part 2)>
Here, a DC power supply system 3 which is a modification (part 2) of the DC power supply system 1 will be described.

(F1. Overall configuration)
FIG. 12 is a diagram schematically showing an overall configuration of DC power supply system 3 according to the modification (No. 2) of the present embodiment.

  Referring to FIG. 12, DC power supply system 3 includes a power conditioner 100, power storage devices 200 </ b> A, 200 </ b> B, and 200 </ b> C, a solar power generation system 800 that is a DC power source, and a power system 900. That is, the DC power supply system 3 is basically the same except that the DC power supply system 1 is configured by connecting the power storage device 200C to the connection terminal 42C. Therefore, detailed description of the same configuration and function as those of DC power supply system 1 will not be repeated. The power storage devices 200A, 200B, and 200C are connected in parallel to each other via the DC bus 30.

  FIG. 13 is a diagram showing an example of the remaining battery voltage-voltage curve of the plurality of storage batteries 210 according to the modification (No. 2) of this embodiment.

  Referring to FIG. 13, the remaining battery voltage-voltage curves of storage batteries 210A, 210B and 210C are shown. It can be seen that in Th2 <SOC <Th1, the storage battery 210A has the smallest voltage change, the storage battery 210B has the next smallest voltage change, and the storage battery 210C has the largest voltage change.

(F2. Charge / discharge operation)
For the configuration of the inverter 100, <C. Since it is the same as that described in the configuration of the inverter>, detailed description thereof will not be repeated.

  Here, it will be described how charging / discharging of the storage batteries 210A, 210B, and 210C changes under the control of the power conditioner 100 with reference to FIG. 13 and the following FIGS. Here, in order to effectively use the storage battery 210, it is assumed that any storage battery 210 is used between Th2 <SOC <Th1.

  FIGS. 14 and 15 are diagrams for explaining the charge / discharge operations of the plurality of storage batteries 210 according to the modification (No. 2) of the present embodiment. 14 and 15 do not illustrate part of the configuration of the power conditioner 100 and the power storage device 200 for ease of explanation, these are configured as shown in FIG. 12 described above. .

  FIG. 16 is a state transition diagram showing a state transition of the plurality of power storage devices 200 in FIGS. 14 and 15. Note that states (A) to (E) and (F) to (I) in FIG. 16 correspond to states (A) to (E) in FIG. 14 and states (F) to (I) in FIG. 15, respectively. ing.

  The charge / discharge behavior of storage batteries 210A, 210B and 210C in FIG. 16 is substantially a combination of the charge / discharge behavior of storage batteries 210A and 210B described in FIG. 5 and the charge / discharge behavior of storage batteries 210B and 210C described in FIG. It is a thing. Here, for ease of explanation, it is assumed that Th3, which is the SOC value that defines the timing at which SW1a is turned on, and Th3 ′, which is the SOC value that defines the timing at which SW1b is turned on, are equal. (Ie, Th3 = Th3 ′). Similarly, Th4 that is the SOC value that defines the timing for turning on SW2a and Th4 ′ that is the SOC value that defines the timing for turning on SW2b are equal (that is, Th4 = Th4 ′). .

First, the states (A) to (E) in FIG. 14 will be described.
Referring to FIGS. 13 to 16, power conditioner 100 turns on switches SW1a, 1b, 1c and SW2a, 2b, 2c for power storage devices 200A, 200B, and 200C, respectively (the state (FIG. 14)). A)) will be described. In addition, the power conditioner 100 acquires each battery residual amount-voltage curve data (for example, FIG. 13) by communicating with the power storage devices 200A to 200C, and the voltage change with respect to the battery residual amount in Th2 <SOC <Th1. The remaining storage batteries 210A and 210B other than the storage battery 210C having the largest value are selected, and the switches SW1 and SW2 corresponding to the selected storage batteries 210 are controlled.

Referring to FIG. 14, in the state (A), the charging path and discharging path of each storage battery 210 are both connected. Therefore, referring to FIG. 13, the voltage relationship in the state (A) becomes Vdc = Va = Vb = Vc = V M.

  In the state (A), at the time of charge control by the power conditioner 100, only the storage battery 210A is charged (arrow Rch21). Moreover, at the time of discharge control by the power conditioner 100, power is discharged only from the storage battery 210A (arrow Rdc21). In other words, the state (A) in FIG. 14 is the same charge / discharge operation as the state (A) in FIG.

Next, power conditioner 100 performs charge control from state (A), and turns off SW1a when power is charged in storage batteries 210B and 210C and SOC _A > Th1. And if the power conditioner 100 further continues charge control, it will change from a state (A) to a state (B) (corresponding to (1) in FIG. 16). Referring to FIG. 13, the voltage relationship in the state (B) is V _M = Va <Vdc = Vb = Vc <V _H.

  In the state (B), when charging control is performed by the power conditioner 100, the storage batteries 210B and 210C are charged with power (arrows Rch22 and Rch23). In addition, during the discharge control by the power conditioner 100, power is discharged from the storage batteries 210B and 210C (arrows Rdc22, Rdc23). In other words, the state (B) of FIG. 14 is the same charge / discharge operation as the state (A) of FIG.

Next, power conditioner 100 performs charge control from state (A), and turns off SW1b when power is charged in storage batteries 210B and 210C and SOC _B > Th1. And if the power conditioner 100 further continues charge control, it will change from a state (B) to a state (C) (corresponding to (2) in FIG. 16). Referring to FIG. 12, the voltage relationship in the state (C) is V _M = Va <Vb = V _H <Vc = Vdc.

  In the state (C), during the charging control by the power conditioner 100, only the storage battery 210C is charged (arrow Rch24). Further, during the discharge control by the power conditioner 100, power is discharged only from the storage battery 210C (arrow Rdc24). In other words, the state (C) in FIG. 14 is the same charge / discharge operation as the state (B) in FIG.

Next, the power conditioner 100 performs charge control from the state (C). When the storage battery 210C is charged with power and SOC _C > Th1, the SOC _C reaches the upper limit, and charging cannot be performed any more. Stop control. And when the power conditioner 100 starts discharge control, electric power will be discharged from the storage battery 210C. When the power conditioner 100 discharges the storage battery 210C until SOC _C = Th5, the state transitions from the state (C) to the state (D) (corresponding to (3) in FIG. 16). Referring to FIG. 12, the voltage relationship in the state (D) is V _M = Va <Vb = Vc = V _H = Vdc. In addition, the power conditioner 100 starts the discharge control, and when the power is discharged from the storage battery 210C and SOC _C <Th1, the charge control is started even if the state (D) is not changed. Thereby, electric power can be charged to the storage battery 210C.

In the state (D), only the storage battery 210C is charged during the charging control by the power conditioner 100 (arrow Rch25). At this time, if SOC _C <Th5, the state (D) transitions to the state (C) (corresponding to (4) in FIG. 16). Further, during the discharge control by the power conditioner 100, power is discharged from the storage batteries 210A and 210B while satisfying Vb = Vc (arrows Rdc25, Rdc26). In other words, the state (D) in FIG. 14 is the same charge / discharge operation as the state (C) in FIG.

Next, the power conditioner 100 performs the discharge control from the state (D), and when the power is discharged from the storage batteries 210B and 210C and SOC _B <Th3 is turned ON, the state is changed from the state (D) to the state. Transition to (B) (corresponding to (5) in FIG. 16). Further, when the power conditioner 100 discharges the storage batteries 210B and 210C until SOC _B = SOC _C = Cr, the state transitions from the state (B) to the state (E) (corresponding to (6) in FIG. 16). Referring to FIG. 12, the voltage relationship in a state (E) becomes Vdc = Va = Vb = Vc = V M.

In the state (E), during charging control by the power conditioner 100, the storage batteries 210B and 210C are charged with power (arrows Rch27 and Rch28). At this time, when SOC _B = SOC _C <Cr, the voltage relationship changes from V _M = Va <Vdc = Vb = Vc and transitions from the state (E) to the state (B) ((7) in FIG. 16). Corresponding). Further, during discharge control by the power conditioner 100, power is discharged only from the storage battery 210A (arrow Rdc27). This is because the discharge from the storage battery 210A has priority because it is Vdc = Va = Vb = Vc = V M.

Next, the power conditioner 100 performs discharge control from the state (E), and when the power is discharged from the storage battery 210A and SOC _A <Th3 is turned ON, when the SW1a is turned ON, the state (E) is changed from the state (E) to the state (A ) (Corresponding to (8) in FIG. 16).

Next, the states (F) to (I) in FIG. 15 will be described.
The power conditioner 100 performs discharge control from the state (A) of FIG. 14, and turns off SW2a when power is discharged from the storage battery 210A and SOC _A <Th2. And if the power conditioner 100 further continues discharge control, it will change to a state (F) from a state (A) (corresponding to (9) of Drawing 16). Referring to FIG. 12, the voltage relationship in a state (F) _becomes V L <Vdc = Vb = Vc <Va = V M.

  In the state (F), at the time of charging control by the power conditioner 100, the storage batteries 210B and 210C are charged with power (arrows Rch29 and Rch30). Further, during the discharge control by the power conditioner 100, power is discharged from the storage batteries 210B and 210C (arrows Rdc29, Rdc30). In other words, the state (F) in FIG. 15 is the same charge / discharge operation as the state (A) in FIG.

Next, power conditioner 100 performs discharge control from the state (F), and turns off SW2b when power is discharged from storage batteries 210B and 210C to satisfy SOC _B <Th2. And if the power conditioner 100 further continues discharge control, it will change from a state (F) to a state (G) (corresponding to (10) in FIG. 16). Referring to FIG. 12, the voltage relationship in a state (G) becomes _{Vdc = Vc <Vb = V L} <Va = V M.

  In the state (G), at the time of charge control by the power conditioner 100, only the storage battery 210C is charged (arrow Rch31). Further, during discharge control by the power conditioner 100, power is discharged only from the storage battery 210C (arrow Rdc31). In other words, the state (G) in FIG. 15 is the same charge / discharge operation as the state (D) in FIG.

Next, the power conditioner 100 performs discharge control from the state (G), and when the power is discharged from the storage battery 210C and SOC _C <Th2, the SOC _C reaches the lower limit, and no further discharge is possible. Stop control. And when the power conditioner 100 starts charge control, electric power will be charged to the storage battery 210C. When the power conditioner 100 charges the storage battery 210C until SOC _C = Th6, the state (G) transitions to the state (H) (corresponding to (11) in FIG. 16). Referring to FIG. 12, the voltage relationship in a state (H) _becomes V L = Vb = Vc = Vdc <Va = V M. In addition, the power conditioner 100 starts the charge control, and when the storage battery 210C is charged with power and SOC _C > Th2, the discharge control is started even if the state (H) is not changed. Thus, electric power can be discharged from the storage battery 210C.

In the state (H), at the time of discharge control by the power conditioner 100, power is discharged only from the storage battery 210C (arrow Rch32). Then, SOC _C <Th6, and the state (H) is changed to the state (G) (corresponding to (12) in FIG. 16). Further, during charging control by power conditioner 100, power is charged in storage batteries 210A and 210B while satisfying Vb = Vc (arrows Rdc32, Rdc33). In other words, the state (H) of FIG. 15 is the same charge / discharge operation as the state (E) of FIG.

Next, when the power conditioner 100 performs charge control from the state (H) and turns on the SW2b when the storage batteries 210B and 210C are charged with SOC _B > Th4, the state (H) is changed to the state (H). Transition to (F) (corresponding to (13) in FIG. 16). Furthermore, when the power conditioner 100 charges the storage batteries 210B and 210C until SOC _B = SOC _C = Cr, the state transitions from the state (F) to the state (I) (corresponding to (14) in FIG. 16). Referring to FIG. 12, the voltage relationship in a state (I) becomes Vdc = Va = Vb = Vc = V M.

In the state (I), at the time of discharge control by the power conditioner 100, power is discharged from the storage batteries 210B and 210C (arrows Rdc33, Rdc34). _Then, it becomes _SOC B = SOC C <Cr, the voltage relationship changes in Vc = Vb = Vdc <Va = V M, the transition from state (I) to the state (F) ((15) in FIG. 16 Correspondence). Moreover, at the time of charge control by the power conditioner 100, only the storage battery 210A is charged (arrow Rch34). This is because the charging of the battery 210A has priority because it is Vdc = Va = Vb = Vc = V M.

Next, the power conditioner 100 performs charge control from the state (I), and when the power is charged in the storage battery 210A and SOC _A > Th4 is turned ON, when the SW2a is turned on, the state (I) is changed from the state (I) to the state (A ) (Corresponding to (16) in FIG. 16).

(F3. Processing procedure)
Next, a control processing procedure executed by power conditioner 100 according to the modification (No. 2) of the present embodiment will be described.

  FIG. 17 is a flowchart illustrating an example of a control processing procedure executed by the power conditioner 100 according to the modification (No. 2) of the present embodiment. Each step shown in FIG. 17 is realized by software processing and / or hardware processing by the control unit 10 included in the power conditioner 100. It is assumed that the initial state of power storage devices 200A, 200B, and 200C is the state (A) shown in FIG.

  Referring to FIG. 17, control unit 10 communicates with each power storage device 200 to obtain battery remaining-voltage curve data of storage batteries 210A, 210B and 210C and information indicating the current remaining battery capacity. get. (Step S50).

  Next, the control unit 10 calculates the slope of the voltage with respect to the battery remaining amount in Th2 <SOC <Th1 based on the battery remaining amount-voltage curve data, and selects a storage battery 210 other than the storage battery having the largest inclination. (Step S52). More specifically, the control unit 10 selects the storage batteries 210A and 210B other than the storage battery 210C having the largest inclination. At this time, the control unit 10 selects the storage battery 210A as the storage battery with the smallest voltage change, and selects the storage battery 210B as the storage battery with the next smallest voltage change.

  Next, the control unit 10 determines whether or not to charge the storage battery 210 (step S54). When not charging (in the case of NO in step S54), the control unit 10 determines whether or not to discharge power from the storage battery 210 (step S77). When not discharging (that is, when neither charging nor discharging) (NO in step S77), control unit 10 repeats the processing from step S1. When discharging (in the case of YES in step S77), the control unit 10 executes the processing from step S78. The processing from step S78 will be described later.

  In the case of charging (in the case of YES in step S54), the control unit 10 executes the charging control (step S56).

Next, the control unit 10 determines whether or not the SOC _A has become larger than Th1 (step S58). If SOC _A is not greater than Th1 (NO in step S58), control unit 10 executes the processing from step S62. On the other hand, when SOC _A is larger than Th1 (YES in step S58), control unit 10 controls to turn off switch SW1a of storage battery 210A (step S60).

Next, the control unit 10 determines whether or not SOC _B is greater than Th1 (step S62). If SOC _B is not greater than Th1 (NO in step S62), control unit 10 executes the processing from step S66. On the other hand, when SOC _B is larger than Th1 (YES in step S62), control unit 10 performs control so that switch SW1b is turned off (step S64).

Next, the control unit 10 determines whether SOC _C is larger than Th1 (step S66). If SOC _C is not greater than Th1 (NO in step S66), control unit 10 executes the processing from step S70. On the other hand, when SOC _C is larger than Th1 (YES in step S66), control unit 10 stops the charging control (step S68).

Next, the control unit 10 determines whether SOC _B is larger than Th4 (step S70). When SOC _B is not greater than Th4 (NO in step S70), control unit 10 executes processing from step S74 described later. On the other hand, when SOC _B is larger than Th4 (YES in step S70), control unit 10 determines whether or not switch SW2b is OFF (step S71). When the switch SW2b is not OFF (ON) (NO in step S71), processing from step S74 described later is executed. On the other hand, when the switch SW2b is OFF (YES in step S71), control is performed to turn on the switch SW2b (step S72).

Next, the control unit 10 determines whether or not SOC _A is larger than Th4 (step S74). If SOC _A is not greater than Th4 (NO in step S74), control unit 10 repeats the process of step S50. On the other hand, when SOC _A is larger than Th4 (YES in step S74), control unit 10 determines whether or not switch SW2a is OFF (step S75). If switch SW2a is not OFF (ON) (NO in step S75), the processing from step S50 is repeated. On the other hand, when the switch SW2a is OFF (YES in step S75), control is performed to turn on the switch SW2a (step S76). And the control unit 10 repeats the process from step S50.

Next, the process after step S78 is demonstrated.
When discharging storage battery 210 (when YES in step S77), control unit 10 performs discharge control (step S78).

Next, the control unit 10 determines whether or not SOC _A is smaller than Th2 (step S80). When SOC _A is not smaller than Th2 (NO in step S80), control unit 10 executes processing from step S84 described later. On the other hand, when SOC _A is smaller than Th2 (YES in step S80), control unit 10 controls to turn off switch SW2a of storage battery 210A (step S82).

Next, the control unit 10 determines whether SOC _B is smaller than Th2 (step S84). If SOC _B is not smaller than Th2 (NO in step S84), control unit 10 executes processing from step S88 described later. On the other hand, when SOC _B is smaller than Th2 (YES in step S84), control unit 10 performs control to turn off switch SW2b (step S86).

Next, the control unit 10 determines whether SOC _C is smaller than Th2 (step S88). When SOC _C is not smaller than Th2 (NO in step S88), control unit 10 executes processing from step S92 described later. On the other hand, when SOC _C is smaller than Th2 (YES in step S88), control unit 10 stops the discharge control (step S90).

Next, the control unit 10 determines whether or not SOC _B is smaller than Th3 (step S92). When SOC _B is not smaller than Th3 (NO in step S92), control unit 10 executes processing from step S96 described later. On the other hand, when SOC _B is smaller than Th3 (YES in step S92), control unit 10 determines whether or not switch SW1b is OFF (step S93). If the switch SW1b is not OFF (ON) (NO in step S93), processing from step S96 described later is executed. On the other hand, when the switch SW1b is OFF (YES in step S93), control is performed to turn on the switch SW1b (step S94).

Next, the control unit 10 determines whether or not SOC _A is smaller than Th3 (step S96). If SOC _A is not smaller than Th3 (NO in step S96), control unit 10 repeats the processing from step S50. On the other hand, when SOC _A is smaller than Th3 (YES in step S96), control unit 10 determines whether or not switch SW1a is OFF (step S97). If switch SW1a is not OFF (ON) (NO in step S97), the processing from step S50 is repeated. On the other hand, when the switch SW1a is OFF (YES in step S97), control is performed to turn on the switch SW1a (step S98). And the control unit 10 repeats the process from step S50.

In the above description, the control unit 10 may control the switch SW1c to be turned off instead of stopping the charging control in step S68. In this case, after step S98 of the discharge-side loop, a process for controlling the switch SW1c to be turned on is added on condition that the SOC _C is smaller than Th1.

Further, the control unit 10 may control the switch SW2c to be turned off instead of stopping the discharge control in step S90. In this case, after step S76 of the charging-side loop, a process for controlling the switch SW2c to be turned on is added on the condition that SOC _C is greater than Th2.

<G. Switch circuit configuration>
The case where the switches SW1 and SW2 are connected to the charging path and the discharging path has been described above, but the circuit configuration of the switch SW is not limited to this.

FIG. 18 is a diagram illustrating another circuit configuration of the switch SW.
Referring to FIG. 18, in pattern A, switch SW3 that does not include a diode is connected in parallel to switch SW1 and switch SW2. Thus, the charging path can be controlled by opening / closing the switch SW1, the discharging path can be controlled by opening / closing the switch SW2, and the charging / discharging path can be controlled by the switch SW3. That is, when the power storage device 200 is charged / discharged, charging / discharging without a diode is enabled by turning on the switch SW3.

  In the pattern B, only the power storage device 200 can be charged by turning on the switch SW1 and turning off the switch SW2, and only the discharge from the power storage device 200 can be performed by turning off the switch SW1 and turning on the switch SW2. By turning on the switches SW1 and SW2, the power storage device 200 can be charged and discharged. Even in this case, when the power storage device 200 is charged and discharged, the switches SW1 and SW2 are turned on to enable charging and discharging without using a diode.

  The power conditioner 100 may control the opening and closing of the switches SW1 to SW3 in accordance with the charge / discharge operation of the power storage device 200 described above.

<H. Other Embodiments>
In the above-described embodiment, the case where the number of power storage devices is two or three has been described. However, the present invention is not limited to this, and four or more power storage devices are connected in parallel via a DC bus. Also good.

  Also, the case where there are as many connection terminals as the number of power storage devices has been described. However, when the power storage devices themselves are provided with input / output connection portions, the power storage devices are connected in parallel via a DC bus in order. It may be.

  Furthermore, when the storage battery connected to the inverter is known and information indicating the sleep system between the remaining battery level and the voltage is stored in advance in the storage unit of the control unit, the information is stored from the power storage device. May not be obtained.

<I. Advantage>
According to this embodiment, even when a plurality of storage batteries are connected in parallel, the connection between the storage battery and the DC bus is controlled based on each battery related information. Therefore, even when storage batteries having different charge / discharge characteristics are connected in parallel via the DC bus, any of the storage batteries can be charged / discharged with a remaining battery level within a predetermined range. That is, it is possible to prevent a situation in which only one of the storage batteries is charged / discharged and the other storage battery is not charged / discharged, and each storage battery can be used effectively.

  In addition, charging / discharging is preferentially performed in descending order of voltage change with respect to the battery remaining amount, so that the DC bus voltage can be further stabilized. In addition, during the switch opening / closing control, a large current does not flow from the storage battery to another storage battery.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1, 2, 3 DC power supply system, 10 control unit, 11 input unit, 12 storage unit, 13 information acquisition unit, 14 selection unit, 15 connection control unit, 16 current control unit, 20 bidirectional DC / AC converter, 21 Bidirectional inverter, 22, 23 Interconnected reactor, 25 Voltage sensor, 26 Control unit, 30 DC bus, 40, 42, 44 Connection terminal, 50, 52 Current sensor, 100 Power conditioner, 200 Power storage device, 210 Storage battery, 220 Management unit, 800 solar power generation system, 810 solar cell, 820 DC / DC converter, 900 power system.

Claims (5)

A power conditioner that is coupled between a plurality of power storage devices including a power storage unit and a power system, and controls each power,
It has a DC bus for transmitting DC power,
The plurality of power storage units are connected in parallel to each other via the DC bus,
The inverter is
A power converter that converts power bidirectionally between the DC bus and the power system;
A control unit for controlling the power of the power storage unit of each power storage device,
The controller is
Based on the information indicating the relationship between the remaining battery level and voltage of each of the power storage units, at least one of the plurality of power storage units other than the power storage unit having the largest change in the voltage with respect to the remaining battery level within a predetermined range. Selecting means for selecting a power storage unit;
A connection that controls connection between the selected power storage unit and the DC bus with respect to the power storage device corresponding to the selected power storage unit based on the remaining battery level of the selected power storage unit and a control means only including,
The predetermined range is between a first threshold value of the remaining battery level and a second threshold value that is smaller than the first threshold value,
The connection control means includes
When the remaining battery level of the selected power storage unit is greater than the first threshold value, the selected power storage unit is connected to the selected power storage unit from the DC bus between the selected power storage unit and the DC bus. The charging path for charging the power of the selected power storage unit is cut off, and the discharge path for discharging the power from the selected power storage unit to the DC bus is connected, and the remaining battery level of the selected power storage unit is If smaller than the second threshold, the charging path is connected and the discharging path is interrupted,
With respect to the power storage device corresponding to the power storage unit determined to have the largest change in voltage with respect to the remaining battery power in the predetermined range by the selection unit, the determined power storage unit and the DC bus A power conditioner that connects the two .   The said control part further contains the acquisition means which acquires the information which shows the battery remaining charge of the said each electrical storage part from the some said electrical storage apparatus, and the information which shows the relationship between the said battery remaining charge and a voltage, The said storage part. The power conditioner according to 1. A charge / discharge current detector for detecting a charge / discharge current of the power storage device;
Wherein the control unit, the detected discharge current further comprises current control means for controlling the power conversion in the power converter unit to a predetermined value, the power conditioner according to claim 1 or 2. A method of controlling a power conditioner that is coupled between a plurality of power storage devices including a power storage unit and a power system, and controls each power,
The inverter is
A DC bus for transmitting DC power;
A power converter that converts power bidirectionally between the DC bus and the power system;
The plurality of power storage units are connected in parallel to each other via the DC bus,
The control method of the inverter is as follows:
Based on the information indicating the relationship between the remaining battery level and voltage of each of the power storage units, at least one of the plurality of power storage units other than the power storage unit having the largest change in the voltage with respect to the remaining battery level within a predetermined range. Selecting a power storage unit;
Controlling connection between the selected power storage unit and the DC bus for the power storage device corresponding to the selected power storage unit based on the remaining battery level of the selected power storage unit. viewing including the door,
The predetermined range is between a first threshold value of the remaining battery level and a second threshold value that is smaller than the first threshold value,
The controlling step includes
When the remaining battery level of the selected power storage unit is greater than the first threshold value, the selected power storage unit is connected to the selected power storage unit from the DC bus between the selected power storage unit and the DC bus. Cutting off the charging path for charging the power of the battery, and connecting a discharging path for discharging the power from the selected power storage unit to the DC bus;
When the remaining battery level of the selected power storage unit is smaller than the second threshold, connecting the charging path and blocking the discharging path;
With respect to the power storage device corresponding to the power storage unit that is determined to have the largest voltage change with respect to the remaining battery level in the predetermined range by the selecting step, the determined power storage unit and the DC bus A method of controlling the inverter , including connecting between the inverter and the inverter. A plurality of power storage devices including a power storage unit;
A power conditioner is coupled between the power storage device and the power system, and controls each power,
The inverter is
It has a DC bus for transmitting DC power,
The plurality of power storage units are connected in parallel to each other via the DC bus,
The inverter is
A power converter that converts power bidirectionally between the DC bus and the power system;
A control unit for controlling the power of the power storage unit of each power storage device,
The controller is
Based on the information indicating the relationship between the remaining battery level and voltage of each of the power storage units, at least one of the plurality of power storage units other than the power storage unit having the largest change in the voltage with respect to the remaining battery level within a predetermined range. Selecting means for selecting a power storage unit;
A connection that controls connection between the selected power storage unit and the DC bus with respect to the power storage device corresponding to the selected power storage unit based on the remaining battery level of the selected power storage unit and a control means only including,
The predetermined range is between a first threshold value of the remaining battery level and a second threshold value that is smaller than the first threshold value,
The connection control means includes
When the remaining battery level of the selected power storage unit is greater than the first threshold value, the selected power storage unit is connected to the selected power storage unit from the DC bus between the selected power storage unit and the DC bus. The charging path for charging the power of the selected power storage unit is cut off, and the discharge path for discharging the power from the selected power storage unit to the DC bus is connected, and the remaining battery level of the selected power storage unit is If smaller than the second threshold, the charging path is connected and the discharging path is interrupted,
With respect to the power storage device corresponding to the power storage unit determined to have the largest change in voltage with respect to the remaining battery power in the predetermined range by the selection unit, the determined power storage unit and the DC bus DC power supply system that connects the two .

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