JP6678342B2 - Power supply system and power storage device - Google Patents

Description

The present invention relates to a power supply system in which a plurality of power storage devices are connected in parallel to supply power to a load, and to the power storage devices.

  In recent years, a system in which a plurality of power storage devices are connected in parallel and a plurality of power storage devices output power in cooperation with each other has become widespread. A configuration in which a plurality of power storage devices are connected in parallel is a configuration that occurs when a new power storage device is retrofitted to an existing power storage device, or when power storage devices are respectively installed at remote locations. In such a configuration, a plurality of power storage installations are generally connected by a communication line. For example, when a plurality of power storage devices operate independently from a commercial power system (hereinafter simply referred to as a system), a phase synchronization signal is transmitted via a communication line (for example, see Patent Document 1).

JP-A-2015-61448

  In the above-described system, a power storage device that has become unable to communicate due to a disconnection of a communication line or the like cannot operate in cooperation with another power storage device, and output has been stopped. Since the communication line is thinner and easier to break than the power line, the power line is connected between the plurality of power storage devices, but a state in which the communication line is broken can sufficiently occur. In an emergency, it is uneconomical that some power storage devices cannot be used due to communication abnormalities.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a power supply system capable of operating a plurality of power storage devices operating in cooperation using communication with a power supply capability as low as possible. And a power storage device.

  In order to solve the above problems, a power supply system according to an embodiment of the present invention includes a plurality of power supply devices connected in parallel to supply power to a load, and the plurality of power supply devices are connected to each other by a communication line. And a control device for controlling the plurality of power supply devices. Among the plurality of power supply devices, a power supply device in which normal communication with the control device has been disabled continues to output to the load according to a predetermined rule.

According to the present invention, it is possible to operate a plurality of power supply devices that are operating in cooperation using communication without reducing the power supply capability as much as possible.
Can be realized.

1 is a diagram for describing a configuration of a power supply system according to an embodiment of the present invention. FIG. 2 is a diagram for describing a configuration of a power supply system in an independent mode according to the first embodiment. FIG. 9 is a diagram for describing a configuration of a power supply system in a self-sustaining mode according to a second embodiment. FIGS. 4A and 4B are diagrams illustrating an example of power-voltage characteristics. FIG. 9 is a diagram for describing a configuration of a power supply system according to a modification.

  FIG. 1 is a diagram for describing a configuration of a power supply system 1 according to an embodiment of the present invention. The power supply system 1 includes a plurality of power storage devices 10 and a master control device 20 connected in parallel. FIG. 1 illustrates an example in which three power storage devices of the first power storage device 10a, the second power storage device 10b, and the third power storage device 10c are connected in parallel, but the number of parallel power storage devices is not limited to three.

  First power storage device 10a includes a first power storage unit 11a, a first power conversion unit 12a, and a first control unit 13a. The first power storage unit 11a includes a lithium ion storage battery, a nickel hydride storage battery, a lead storage battery, an electric double layer capacitor, a lithium ion capacitor, and the like. Further, first power storage unit 11a includes a monitoring circuit that monitors at least the voltage and current of the storage battery or the capacitor. The monitoring circuit periodically notifies the first control unit 13a of monitoring data including the voltage and current detected from the storage battery or the capacitor.

  The first power conversion unit 12a converts DC power discharged from the first power storage unit 11a into AC power, and converts the AC power into the system 2 or a power line for independent output separated from the system 2 (hereinafter, an independent power line). 40). Further, first power conversion unit 12a converts AC power of system 2 into DC power, and charges the DC power to first power storage unit 11a. Specifically, the first power conversion unit 12a includes a single bidirectional inverter or a combination of a bidirectional inverter and a bidirectional DC-DC converter. The bidirectional DC-DC converter and / or the bidirectional inverter charges / discharges the first power storage unit 11a with a constant current (CC) based on a current command value specified by the first control unit 13a. Further, the bidirectional DC-DC converter and / or the bidirectional inverter charges / discharges the first power storage unit 11a at a constant voltage (CV) based on a voltage command value specified by the first control unit 13a.

  The first control unit 13a controls the first power conversion unit 12a. The configuration of the first control unit 13a can be realized by cooperation of hardware resources and software resources, or only by hardware resources. Analog elements, microcomputers, DSPs, ROMs, RAMs, FPGAs, and other LSIs can be used as hardware resources. A program such as firmware can be used as a software resource.

  The configuration of the second power storage device 10b and the third power storage device 10c is the same as that of the first power storage device 10a. The power line for system interconnection of the first power conversion unit 12a (hereinafter, referred to as system power line 50), the system power line 50 of the second power conversion unit 12b, and the system power line 50 of the third power conversion unit 12c are connected and connected. 2 is connected. Although not shown in FIG. 1, a general load is connected to the system power line 50 after the merging. The independent power line 40 of the first power converter 12a, the independent power line 40 of the second power converter 12b, and the independent power line 40 of the third power converter 12c are connected. The independent load 3 can be connected to the independent power line 40 after the merging, and can be used as an emergency power supply at the time of a power failure of the system 2.

  Master control device 20 is connected to first control unit 13a to third control unit 13c of first power storage device 10a to third power storage device 10c via communication line 30, and controls power supply system 1 as a whole. For example, the master control device 20 and the first control unit 13a to the third control unit 13c are connected by a cable compliant with the RS-485 standard, and perform serial communication according to a communication system compliant with the standard.

  The first control unit 13a to the third control unit 13c operate the first power conversion unit 12a to the third power conversion unit 12c in the grid connection mode in normal times. When the power failure of the system 2 is detected, the first control unit 13a to the third control unit 13c switch the first power conversion unit 12a to the third power conversion unit 12c to the self-sustaining mode. That is, the output destinations of the first power conversion unit 12a to the third power conversion unit 12c are switched from the system power line 50 to the independent power line 40, respectively. Hereinafter, in the present specification, attention is paid to control in the self-sustaining mode.

(Example 1)
FIG. 2 is a diagram illustrating the configuration of the power supply system 1 in the self-sustaining mode according to the first embodiment. In the autonomous mode, the first power converter 12a-third power converter 12c cannot detect the phase of the system voltage. Therefore, in the self-sustaining mode according to the first embodiment, the master control device 20 generates a synchronization signal for synchronizing the voltage phases, and notifies the first control unit 13a to the third control unit 13c.

  The first control unit 13a to the third control unit 13c generate a voltage command value corresponding to the received synchronization signal, generate a drive signal corresponding to the voltage command value and a predetermined carrier, and generate a first power conversion unit 12a Driving the third power converter 12c; The voltage command value is set to, for example, 100 / 200V. This value may be a value held in advance by the first control unit 13a to the third control unit 13c or a value received from the master control device 20 via the communication line 30.

  In the self-sustaining mode according to the first embodiment, the first power converter 12a to the third power converter 12c operate by voltage control. Hereinafter, a state in which the control unit 13 has become unable to communicate due to a disconnection of the communication line 30 or a failure of a circuit or a program executing the communication process will be considered. Hereinafter, a state in which the communication line 30 between the master control device 20 and the third control unit 13c is disconnected and normal communication with the third control unit 13c is disabled is considered. Note that normal communication is possible between the master control device 20 and the first control unit 13a and the second control unit 13b, and the disconnection of the independent power line 40 is not performed.

  In the first embodiment, the third control unit 13c that has become unable to communicate switches the third power conversion unit 12c from voltage control to current control, and continues power output to the independent load 3. The independent power line 40 of the third power converter 12c is connected by the independent power line 40 of the other first power converter 12a and the second power converter 12b. Therefore, the voltage phase supplied to the independent load 3 can be specified by detecting the zero cross of the AC voltage output by the first power conversion unit 12a and the second power conversion unit 12b. Specifically, the third control unit 13c acquires a detection voltage from a voltage detection unit (not shown) for detecting the voltage of the independent power line 40 of the third power conversion unit 12c, and specifies the voltage phase of the independent power line 40 I do.

  The third control unit 13c generates a current command value corresponding to the specified phase, generates a drive signal corresponding to the current command value and a predetermined carrier, and drives the third power conversion unit 12c. As the current command value, a preset current value (for example, 1 A) can be used. Further, the current value output immediately before the communication is disabled may be used. Further, the current value received from the master control device 20 immediately before the communication is disabled may be used.

  Further, the current command value may be determined as follows. Third control unit 13c acquires the voltage and current of the internal storage battery or capacitor from third power storage unit 11c, and estimates the SOC (State Of Charge) of the storage battery or capacitor. The SOC can be estimated by, for example, an OCV (Open Circuit Voltage) method or a current integration method. Since these estimation methods are general techniques, detailed description thereof will be omitted. Based on the estimated SOC, the third control unit 13c determines a current value capable of equal output for a preset backup period (for example, 3 days, 8 hours) and sets the current value to the current command value.

  With the above control, the fixed power is output from the third power storage device 10c, but the fluctuation of the independent load 3 is absorbed by at least one of the first power storage device 10a and the second power storage device 10b.

(Example 2)
FIG. 3 is a diagram illustrating the configuration of the power supply system 1 in the self-sustaining mode according to the second embodiment. In the second embodiment, the connection between the independent load 3 and the junction N1 of the independent power line 40 of the first power converter 12a, the independent power line 40 of the second power converter 12b, and the independent power line 40 of the third power converter 12c. A current sensor CT for detecting a current flowing through the power line is provided. The current sensor CT notifies the master controller 20 of the detected current value.

  In the self-sustaining mode according to the second embodiment, the master control device 20 sets one of the first power storage device 10a to the third power storage device 10c connected in parallel as the master device and sets the other as the slave device. In the example shown in FIG. 3, the first power storage device 10a is set as a master device. When designated by the master control device 20 as the master unit, the first control unit 13a generates a voltage command value of a predetermined phase, generates a drive signal corresponding to the voltage command value and a predetermined carrier, and The power converter 12a is driven. The first control unit 13a notifies the master control device 20 of the output current of the first power conversion unit 12a.

  Master control device 20 subtracts the output current value of first power conversion unit 12a from the load current value output to independent load 3 acquired from current sensor CT. The target current value of each slave device is determined by dividing the current value after subtraction by the number of slave devices. The method of determining the target current value of each slave device by dividing the current value after subtraction by the number of slave devices is an example, and another method may be used. For example, the target current value of each slave device may be determined according to the SOC of the power storage unit of each slave device. More specifically, as the SOC of the power storage unit is higher, a larger current is output. For example, when the SOC of the second power storage unit 11b is 60% and the SOC of the third power storage unit 11c is 30%, the current is output from the second power storage unit 11b and the third power storage unit 11c at a ratio of 2: 1. The master control device 20 notifies the determined current target value to each slave device (in the present embodiment, the second control unit 13b and the third control unit 13c). The second control unit 13b and the third control unit 13c use the target current value received from the master control device 20 as a current command value, generate a drive signal corresponding to the current command value and a predetermined carrier, and perform the second power conversion. Unit 12b and the third power conversion unit 12c.

  Hereinafter, similarly to the first embodiment, a state in which the communication line 30 between the master control device 20 and the third control unit 13c is disconnected and normal communication with the third control unit 13c is disabled is considered. Note that normal communication is possible between the master control device 20 and the first control unit 13a and the second control unit 13b, and the disconnection of the independent power line 40 is not performed.

  In the second embodiment, the third control unit 13c that has become unable to communicate sets the current value determined by itself, instead of the target current value received from the master control device 20, as the current command value, and sets the independent load 3 by the current control. Continue power output to As in the first embodiment, a preset current value (for example, 1 A) can be used as the current value determined by the third control unit 13c itself. Further, the current value output immediately before the communication is disabled may be used. Further, the current value received from the master control device 20 immediately before the communication is disabled may be used. Further, a current value that enables uniform output for a preset backup period (for example, 3 days, 8 hours) may be used based on the SOC of the storage battery or the capacitor inside the third power storage unit 11c.

  When using a preset current value (for example, 1 A), the master control device 20 cannot communicate with the output current value of the first power conversion unit 12a from the load current value acquired from the current sensor CT. A current value (for example, 1 A) preset for the slave device is subtracted. If communication is not possible between a plurality of slave units, a value obtained by multiplying a preset current value by the number of units is subtracted. The current value after the subtraction is divided by the number of slave units having normal communication to determine the target current value of each slave unit having normal communication.

  In the first embodiment, the third control unit 13c that has become unable to communicate determines the output current value by itself, and thereafter fixes the output current value. In the following description, a mechanism for changing the determined output current value according to the fluctuation of the independent load 3 is introduced.

  Based on the power-voltage characteristic, master control device 20 responds to a change in the output power of first power converter 12a and the second power converter 12b with normal communication (a change in independent load 3) by the first power converter. The output voltage of the second power converter 12b is adjusted. The third control unit 13c determines the output power according to the voltage of the independent power line 40 of the third power conversion unit 12c based on the power-voltage characteristics, and changes the output power to a voltage command value corresponding to the output power.

  FIGS. 4A and 4B are diagrams illustrating an example of power-voltage characteristics. FIG. 4A shows an example of a drooping power-voltage characteristic, and FIG. 4B shows an example of a step-like power-voltage characteristic. The master control device 20 and the first control unit 13a to the third control unit 13c each hold common power-voltage characteristics. 4A and 4B, when the output power of the first power converter 12a and the second power converter 12b with normal communication increases, the master control device 20 becomes independent (independent). The load 3 rises), and the output voltage decreases. When the voltage of the independent power line 40 of the third power conversion unit 12c decreases, the third control unit 13c increases the output power according to the voltage change rate based on the power-voltage characteristics. Conversely, when the output power of the first power conversion unit 12a and the second power conversion unit 12b in which communication is normal decreases (the independent load 3 decreases), the master control device 20 changes the power change rate based on the power-voltage characteristics. The output voltage is increased according to. When the voltage of the independent power line 40 of the third power conversion unit 12c increases, the third control unit 13c decreases the output power according to the voltage change rate based on the power-voltage characteristics. In some cases, a common power-voltage characteristic is not used between the master control device 20 and the first control unit 13a to the third control unit 13c. For example, when a storage battery having another double output capacity is included, it is reasonable to set the power of the storage battery to double at the same output voltage.

(Example 3)
In the first embodiment, the third control unit 13c that has become unable to communicate switches the control of the third power conversion unit 12c from voltage control using communication to stand-alone current control. In the third embodiment, the communication-disabled third control unit 13c switches the control of the third power conversion unit 12c from voltage control using communication to voltage control using droop control. In the third embodiment, the master control device 20 and the first control unit 13a to the third control unit 13c commonly hold the drooping power-voltage characteristics as shown in FIG.

  Based on the power-voltage characteristic, master control device 20 responds to a change in the output power of first power converter 12a and the second power converter 12b with normal communication (a change in independent load 3) by the first power converter. The output voltage of the second power converter 12b is changed. When the output voltage changes, the output power changes accordingly. By repeating this, the output power and the output voltage converge to a position where they are balanced. Master control device 20, and first power storage device 10a and second power storage device 10b with normal communication behave as one power storage device as a whole.

  The third control unit 13c changes the output voltage of the third power conversion unit 12c according to the fluctuation of the output power of the third power conversion unit 12c (the fluctuation of the independent load 3) based on the power-voltage characteristics. When the output voltage changes, the output power changes accordingly. By repeating this, the output power and the output voltage converge to a position where they are balanced.

(Example 4)
In the second embodiment, the third control unit 13c that has become unable to communicate switches the control of the third power conversion unit 12c from current control using communication to stand-alone current control. In the fourth embodiment, the third control unit 13c in which communication is disabled switches the control of the third power conversion unit 12c from current control using communication to voltage control using droop control. Other configurations are the same as those of the third embodiment, and thus the description is omitted.

  As described above, according to the present embodiment, when the third control unit 13c becomes unable to communicate, the third power conversion unit 12c of the third power storage device 10c switches from voltage control using communication from the master control device 20 , Switching to voltage control using stand-alone current control or droop control. Thereby, it is possible to continuously discharge from the third power storage unit 11c of the third power storage device 10c in which communication has been disabled. Therefore, the energy of the third power storage unit 11c can be effectively used without waiting for the repair of the communication line 30. Therefore, it is possible to realize an operation in which a decrease in the power supply capability of the power supply system 1 is minimized.

  The present invention has been described based on the embodiments. The embodiments are exemplifications, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and that such modifications are also within the scope of the present invention. .

  FIG. 5 is a diagram for describing a configuration of a power supply system 1 according to a modification. The power supply system 1 according to the modification has a configuration in which the function of the above-described master control device 20 is provided to the first control unit 13a of the first power storage device 10a. The operation of the first control unit 13a as the master unit is the same as the operation of the master control device 20 described above. According to the modification, the system configuration can be simplified as compared with the power supply system 1 of FIG.

  The embodiment may be specified by the following items.

[Item 1]
A plurality of power supply devices (10a-10c) connected in parallel for supplying power to the load (3);
A control device (20) connected to the plurality of power supply devices (10a-10c) via a communication line (30) and controlling the plurality of power supply devices (10a-10c);
Among the plurality of power supply devices (10a-10c), the power supply device (10c) for which normal communication with the control device (20) has been disabled is output to the load (3) according to a predetermined rule. Power supply system (1) characterized by continuing.
According to this, even in the power supply device (10c) in which communication is disabled due to disconnection of the communication line (30) or the like, output can be continued independently regardless of communication.
[Item 2]
The power supply device (10c) in which the communication is disabled operates under the control of adjusting the output voltage to the reference voltage value before the communication is disabled, and after the communication is disabled, the output current is set to the reference current value. The power supply system (1) according to item 1, wherein the power supply system (1) is operated by matching control.
According to this, even if the power supply device (10c) operates by voltage control, the output can be continued independently after the communication is disabled.
[Item 3]
The power supply device (10c) in which the communication has been disabled is controlled by adjusting the output current to the current value received from the control device (20) via the communication line (30) before the communication is disabled. The power supply system (1) according to item 1, wherein the power supply system operates under control to adjust an output current to a reference current value after the communication is disabled.
According to this, even if the power supply device (10c) operates according to the output current command value from the control device (20), it is possible to continue the output independently after communication is disabled.
[Item 4]
The power supply system (1) according to item 2 or 3, wherein the reference current value is a fixed value.
According to this, it is possible to easily perform current control after communication is disabled.
[Item 5]
The power supply system (1) according to item 4, wherein the fixed value is a value preset in the power supply device (10c).
According to this, since the fixed value may be written at the time of shipment, implementation is easy.
[Item 6]
The control device (20) calculates the current value according to the state of the load (3), transmits the calculated current value to the plurality of power supply devices (10a-10c),
The power supply system (1) according to item 4, wherein the power supply device (10c) in which the communication is disabled sets a current value received last before the communication is disabled to the fixed value. ).
According to this, it is possible to optimize the output of the power supply device (10c) that has become unable to communicate with the load (3).
[Item 7]
The power supply device (10c) includes:
A power storage unit (11c);
A power converter (12c) that converts DC power supplied from the power storage unit (11c) into AC power and outputs the AC power;
A control unit (13c) for controlling the power conversion unit (12c),
The control unit (13c) of the power supply device (10c) in which the communication has been disabled calculates the reference current value based on the remaining capacity of the power storage unit (11c) and the set output duration time. 4. The power supply system (1) according to item 2 or 3, characterized in that:
According to this, for example, an operation such as “output continuously for three days” can be performed by the power supply device (10c) in which communication is disabled.
[Item 8]
The power supply device (10c) in which the communication is disabled, sets the current value output last before the communication is disabled as the reference current value, wherein the reference current value is used as the reference current value. Power supply system (1).
According to this, the output of the power supply device (10c) can be optimized according to the load (3). The calculation in the master control device (20) is unnecessary.
[Item 9]
When the control device (20) detects the power supply device (10c) in which normal communication is disabled, the control device (20) changes the output voltage according to the total output power of the power supply device (10a, 10b) capable of normal communication. The power supply system (1) according to any one of items 1 to 8, wherein the determined output voltage is transmitted to the power supply device (10a, 10b) capable of normal communication.
According to this, a command can be sent to the power supply device (10c) in which communication has been disabled without using the communication line (30).
[Item 10]
The power supply system (1) according to item 9, wherein the output voltage has a characteristic of decreasing in a direction in which the total output power increases.
According to this, the power supply system (1) has a drooping characteristic, which leads to stability of the entire power supply system (1).
[Item 11]
The power supply device (10c) in which the communication is disabled changes the output power according to a voltage change of an output line (40) connected to the load (3). Power supply system (1) according to any one of the above.
According to this, it is possible to adjust the output of the power supply device (10c) in which communication has been disabled according to the size of the load (3).
[Item 12]
The power supply device (10c) in which the communication is disabled increases the output power as the voltage of the output line (40) connected to the load (3) decreases. Power supply system (1) according to any one of the above.
According to this, the power supply system (1) has a drooping characteristic, which leads to stability of the power supply system (1).
[Item 13]
The power supply device (10c) in which the communication is disabled operates under the control of adjusting the output voltage to the reference voltage value before the communication is disabled, and normal communication is enabled after the communication is disabled. 3. The power supply system (1) according to item 1, characterized in that the power supply system (1) operates under control to match a voltage value determined by droop control with the power supply devices (10a, 10b).
According to this, by using the droop control, a stable operation can be performed without communication.
[Item 14]
The power supply device (10c) in which the communication is disabled operates under the control of adjusting the output current to the reference current value before the communication is disabled, and after the communication is disabled, the output voltage is reduced to the normal communication. The power supply system (1) according to item 1, characterized in that the power supply system (1) operates under control to match a voltage value determined by droop control with a power supply device (10a, 10b) capable of performing the control.
According to this, by using the droop control, a stable operation can be performed without communication.
[Item 15]
The power supply system (1) according to any one of items 1 to 14, wherein the control device (20) is a device independent of the plurality of power supply devices (10a to 10c).
According to this, a system can be configured even with a power supply device (10a-10c) having no control function.
[Item 16]
The power supply system (1) according to any one of items 1 to 14, wherein the control device (20) is built in one of the plurality of power supply devices (10a to 10c).
According to this, there is no need to separately install an independent control device (20).
[Item 17]
One of a plurality of power supply devices (10a-10c) connected in parallel for supplying power to the load (3),
A communication line (30) is connected to the plurality of power supply devices (10a-10c) to disable normal communication with the control device (20) that controls the plurality of power supply devices (10a-10c). The power supply device (10c), wherein output to the load (3) is continued in accordance with a predetermined rule even when the power supply device (10) has become inactive.
According to this, even in the power supply device (10c) in which communication is disabled due to disconnection of the communication line (30) or the like, output can be continued independently regardless of communication.

  Reference Signs List 1 power supply system, 2 systems, 3 independent load, 10a first power storage device, 10b second power storage device, 10c third power storage device, 20 master control device, 30 communication line, 40 independent power line, 50 system power line, 11a first Power storage unit, 12a first power conversion unit, 13a first control unit, 11b second power storage unit, 12b second power conversion unit, 13b second control unit, 11c third power storage unit, 12c third power conversion unit, 13c 3 control unit, CT current sensor.

Claims (17)

A system power line connected to a commercial power system and a general load, and a plurality of parallel connected in parallel to each of the independent power lines connected to the independent load and for supplying an emergency power supply at the time of a power outage of the commercial power system . A power storage device,
A control device that is connected to the plurality of power storage devices by a communication line and controls the plurality of power storage devices,
During a power outage of the commercial power system, the plurality of power storage devices switch output destinations from the system power line to the independent power line, respectively, and among the plurality of power storage devices, normal communication with the control device is disabled. The power supply system according to claim 1 , wherein the power storage device continues discharging from the power storage unit included in the power storage device to the independent load according to a predetermined rule.   The power storage device in which the communication is disabled operates under the control of adjusting the output voltage to the reference voltage value before the communication is disabled, and operates under the control of adjusting the output current to the reference current value after the communication is disabled. The power supply system according to claim 1, wherein:   The communication-disabled power storage device operates under the control of adjusting the output current to the current value received via the communication line from the control device before the communication is disabled, and after the communication is disabled. The power supply system according to claim 1, wherein the power supply system operates under control to adjust an output current to a reference current value.   The power supply system according to claim 2, wherein the reference current value is a fixed value.   The power supply system according to claim 4, wherein the fixed value is a value preset in the power storage device. The control device calculates the current value according to the state of the independent load, transmits the calculated current value to the plurality of power storage devices,
4. The power supply system according to claim 3, wherein the power storage device in which the communication is disabled uses a current value received last before the communication is disabled as the reference current value. 5. The power storage device,
Power storage unit,
A power conversion unit that converts DC power supplied from the power storage unit into AC power and outputs the AC power,
A control unit that controls the power conversion unit,
4. The control unit of the power storage device in which the communication is disabled calculates the reference current value based on the remaining capacity of the power storage unit and a set output duration time. 5. A power supply system according to claim 1.   4. The power supply system according to claim 2, wherein the power storage device in which the communication is disabled uses a current value output last before the communication is disabled as the reference current value. 5. .   When the control device detects a power storage device in which normal communication is disabled, the control device determines an output voltage according to the total output power of the power storage device capable of normal communication, and determines the determined output voltage by the normal communication. The power supply system according to claim 1, wherein the power is transmitted to a possible power storage device.   The power supply system according to claim 9, wherein the output voltage has a characteristic of decreasing in a direction of increasing the total output power.   The power supply system according to any one of claims 1 to 10, wherein the power storage device in which the communication is disabled changes an output current according to a voltage change of the independent power line.   The power supply system according to any one of claims 1 to 11, wherein the power storage device in which the communication is disabled increases the output current as the voltage of the independent power line decreases.   The communication-disabled power storage device operates under the control of adjusting the output voltage to the reference voltage value before the communication is disabled, and after the communication is disabled, the power storage device can perform normal communication with the power storage device. The power supply system according to claim 1, wherein the power supply system operates under control to match a voltage value determined by droop control.   The power storage device in which the communication is disabled operates under the control of adjusting the output current to the reference current value before the communication is disabled, and outputs the output voltage after the communication is disabled. The power supply system according to claim 1, wherein the power supply system operates under control to match a voltage value determined by droop control with the device.   The power supply system according to claim 1, wherein the control device is a device independent of the plurality of power storage devices.   The power supply system according to any one of claims 1 to 14, wherein the control device is incorporated in any of the plurality of power storage devices. A system power line connected to a commercial power system and a general load, and a plurality of parallel-connected power supply lines connected to an independent load and each of the independent power lines for supplying an emergency power supply during a power outage of the commercial power system , One of the power storage devices,
The plurality of power storage devices are connected to the plurality of power storage devices via a communication line, and at the time of a power outage of the commercial power system, the plurality of power storage devices switch output destinations from the system power lines to the independent power lines, respectively, to control the plurality of power storage devices. The power storage device according to a predetermined rule , continues to discharge from the power storage unit included in the power storage device to the self-sustaining load, even when normal communication with the control device that performs the operation becomes impossible.

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