JP5799254B2 - Power distribution system - Google Patents

Description

  The present invention relates to a power distribution system that supplies power from a power system to a load.

  In recent years, a DC supply type distribution system that supplies DC power from a DC distribution device such as a solar cell or a fuel cell to a load is becoming common from the viewpoint of distribution efficiency. Conventionally, for example, a configuration disclosed in Patent Document 1 has been adopted as a DC supply type distribution system. In the DC supply type distribution system, as shown in FIG. 8, a solar cell 101 that converts light energy from the sun into electric energy (DC power), and DC power generated by the solar cell 101 to an appropriate output voltage Vout. A converter 103 that converts and supplies power to a load, a fuel cell 102 that generates power by a chemical reaction of a substance, and a converter 104 that converts DC power generated by the fuel cell 102 to an appropriate output voltage Vout and supplies power to the load And a DC load 105 that is operated by DC power from the solar cell 101 and the fuel cell 102.

  The solar cell 101 has output characteristics as shown in FIG. 7, and the output power of the solar cell 101 varies greatly depending on its operating voltage. If the operation voltage of the solar cell 101 can be controlled by the converter 103 so as to operate at Vmp, the maximum output power Pmax can be output from the solar cell 101, and the solar cell 101 is efficiently used. Control for outputting the output power from the solar cell 101 at Pmax and using the solar cell 101 to the maximum is referred to as maximum output operation point tracking control (hereinafter referred to as MPPT control).

  The fuel cell 102 also has a power generation rule suitable for itself. In the power generation rule, for example, the maximum output power is defined, or a sudden change in the generated power is regulated. According to this power generation rule, since it is used in a mode suitable for the fuel cell 102, it is possible to efficiently extract electric power from the fuel cell 102 and to extend the life of the fuel cell 102.

As described above, in the DC power generation devices such as the solar cell 101 and the fuel cell 102, there is an actual benefit of generating electric power according to the respective circumstances such as the power generation rule and the MPPT control.
For example, as shown in Patent Document 2, there is a DC power distribution system including a storage battery. In this power distribution system, the storage battery is mainly used as a backup for discharging when the generated power from the DC power generator is reduced.

JP 2009-232674 A JP 2009-159730 A

  By the way, in the power distribution system shown in the above-mentioned Patent Document 1, the power generated by the solar cell 101 or the fuel cell 102 and the power consumed by the DC load 105 ignore the loss in various power conversion devices and the loss in wiring. The same power. That is, the power exchanged in the DC power distribution system is determined by the power consumption of the DC load 105. That is, even when the power generation capacity of the solar cell 101 or the fuel cell 102 can exceed the power consumption, only the power consumption of the DC load 105 can be generated, resulting in inefficient operation. On the other hand, when the power consumption exceeds the generated power according to the MPPT control and the power generation rules of the solar cell 101 and the fuel cell 102, for example, the power may be output from the fuel cell 102 against the power generation rules. Conceivable. However, this is not preferable in terms of power generation efficiency and life of the fuel cell 102 as described above.

  As described above, in a DC power generation device such as the solar cell 101 and the fuel cell 102, depending on the power consumption (demand power) of the DC load 105, there is a possibility that power generation according to the MPPT control and the power generation rule cannot be performed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power distribution system capable of generating power suitable for itself in a DC power generation device regardless of demand power of a DC load.

  One form of a power distribution system according to the present invention is a DC power in which DC power generated by a DC power generator that generates the maximum DC power when the operating voltage is the maximum output voltage is supplied to a DC load via a DC wiring. A system, an AC power system that is linked to the DC power system and supplied with AC power from an AC power source via AC wiring, and converts AC power supplied from the AC wiring into DC power, from the DC wiring A bidirectional converter that converts supplied DC power into AC power, and the DC power generator connected to the DC wiring and controlling the output power so that the operating voltage of the DC power generator becomes the maximum output voltage. A DC / DC converter for generating the maximum DC power and supplying DC power generated by the DC power generator to the DC load; and a voltage of the DC wiring Voltage detecting means for detecting, a battery connected to the DC wiring, and the DC wiring and the battery are provided between the DC wiring and the battery, and the battery is charged by the power of the DC wiring, and the power of the battery is supplied to the DC wiring. A charging / discharging circuit for discharging the electric power, a bidirectional converter, the DC / DC converter, and a control unit for controlling the charging / discharging circuit, and the supply power and the direct current that are the power supplied by the direct current wiring When the demand power, which is the power required by the load, is balanced, the voltage of the DC wiring is the first command value, the voltage smaller than the first command value is the second command value, and the first command When the second threshold value is set between the value and the second command value, the control unit detects that the voltage of the DC wiring detected by the voltage detection means is larger than the second threshold value. The DC converter controls the DC / DC converter so that the DC power generator generates the maximum DC power, and sets the bidirectional converter so that the voltage of the DC wiring becomes the first command value. And when the voltage of the DC wiring detected and detected by the voltage detection means is equal to or lower than the second threshold value, the charge / discharge circuit is activated, and the DC power generator generates the maximum DC power. Controlling the DC / DC converter so as to control the bidirectional converter so that the voltage of the DC wiring becomes the first command value, and the voltage of the DC wiring detected by the voltage detecting means is When the voltage is less than the second command value, the DC power generator controls the DC / DC converter so that the maximum DC power is generated, and the voltage of the DC wiring is the second command value. The bidirectional converter and the charge / discharge circuit are controlled so that

  According to the present invention, in the power distribution system, the DC power generator can generate power suitable for itself regardless of the demand power of the DC load.

The block diagram which shows the structure of the power distribution system in 1st Embodiment. The block diagram which expanded a part of FIG. 1 in 1st Embodiment. The block diagram which shows the structure of the converters 55-59 in 1st Embodiment. (A) in 1st Embodiment is a graph which shows transition of 1st and 2nd threshold value, 1st and 2nd command value, and voltage V, (b) shows transition of 1st command value and voltage V. Graph. (A) in 1st Embodiment is a flowchart which shows the process sequence of an electric power feeding program, (b) is a flowchart which shows the process sequence of a reverse power flow regulation program. The block diagram which expanded a part of FIG. 1 in 2nd Embodiment. The graph which shows a solar cell voltage-solar cell power characteristic. The block diagram which shows the structure of the conventional power distribution system.

(First embodiment)
A first embodiment that embodies a power distribution system according to the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, a home is provided with a power distribution system 1 that supplies power to various devices (such as lighting devices, air conditioners, home appliances, and audiovisual devices) installed in the home. In addition to the electric power of the commercial AC power supply (AC power supply) 2 for home use, the power distribution system 1 also supplies the electric power of the solar cell 3 generated by sunlight and the electric power of the fuel cell 16 generated by a chemical reaction of substances to various devices. Supply. The power distribution system 1 also supplies power to an AC device 6 that operates by inputting AC power (AC power) in addition to the DC device 5 that operates by inputting DC power (DC power).

  The power distribution system 1 is provided with a control unit 7 and a DC distribution board (built-in DC breaker) 8 as its distribution board. The power distribution system 1 is provided with a control unit 9 and a relay unit 10 as devices for controlling the operation of the DC device 5 in the house.

  An AC distribution board 11 for branching an AC power supply is connected to the control unit 7 via a cross flow connection line 12. The AC power distribution panel 11 is connected to an AC power source 2 and an AC device 6 via an AC power line 23. A solar cell 3 is connected to the control unit 7 via a DC power line 13 and a fuel cell 16 is connected via a DC power line 15. The control unit 7 takes in AC power from the AC distribution board 11 and DC power from the solar cell 3 and the fuel cell 16 and converts these powers into predetermined DC power as a device power source. Then, the control unit 7 outputs the converted DC power to the DC distribution board 8 via the DC power line 14. The control unit 7 not only takes in AC power, but also converts the power of the solar cell 3 and the fuel cell 16 into AC power and supplies it to the AC distribution board 11. Further, the control unit 7 exchanges data with the DC distribution board 8 via the signal line 17.

  The DC distribution board 8 is a kind of breaker that supports DC power. The DC distribution board 8 branches the DC power input from the control unit 7 and outputs the branched DC power to the control unit 9 via the DC power line 18 or relays via the DC power line 19. Or output to the unit 10. The DC distribution board 8 exchanges data with the control unit 9 through the signal line 44 and exchanges data with the relay unit 10 through the signal line 45.

  A plurality of DC devices 5 are connected to the control unit 9. These DC devices 5 are connected to the control unit 9 via a DC supply line 22 that can carry both DC power and data by a pair of lines. The DC supply line 22 superimposes a communication signal for transmitting data with a high-frequency carrier wave on a DC voltage serving as a power source for the DC device, so that both power and data are transferred to the DC device 5 through a pair of lines. Transport. The control unit 9 acquires the DC power supply of the DC device 5 via the DC power line 18 and controls which DC device 5 based on the operation command obtained from the DC distribution board 8 via the signal line 44. Know what to do. Then, the control unit 9 controls the operation of the DC device 5 by outputting a DC voltage and an operation command to the instructed DC device 5 via the DC supply line 22.

  A switch 43 that is operated when switching the operation of the DC device 5 in the house is connected to the control unit 9 via the DC supply line 22. In addition, a sensor 24 that detects a radio wave transmitted from an infrared remote controller, for example, is connected to the control unit 9 via a DC supply line 22. Therefore, not only the operation instruction from the DC distribution board 8 but also the operation of the switch 43 and the detection of the sensor 24, a communication signal is sent to the DC supply line 22 to control the DC device 5.

  A plurality of DC devices 5 are connected to the relay unit 10 via individual DC power lines 25, respectively. The relay unit 10 acquires the DC power supply of the DC device 5 via the DC power line 19 and determines which DC device 5 is to be operated based on an operation command obtained from the DC distribution board 8 via the signal line 45. To grasp. The relay unit 10 controls the operation of the DC device 5 by turning on / off the power supply to the DC power line 25 with respect to the instructed DC device 5 using a built-in relay. In addition, a plurality of switches 46 for manually operating the DC device 5 are connected to the relay unit 10. By turning on / off the power supply to the DC system power line 25 by the operation of the switch 46, the DC is performed. The device 5 is controlled.

  The DC distribution board 8 is connected to a DC outlet 27 built in a house in the form of a wall outlet or a floor outlet, for example, via a DC power line 28. If a plug (not shown) of a DC device is inserted into the DC outlet 27, DC power can be directly supplied to the device.

  Further, between the AC distribution board 11 and the AC power supply 2, a power meter 29 capable of remotely measuring the amount of use of the AC power supply 2 is connected. The power meter 29 is equipped with not only a function of remote meter reading of the amount of commercial power used, but also a function of power line carrier communication and wireless communication, for example. The power meter 29 transmits the meter reading result to an electric power company or the like via power line carrier communication or wireless communication.

  The power distribution system 1 is provided with a network system 30 that enables various devices in the home to be controlled by network communication. The network system 30 is provided with a home server 31 as a control unit of the system 30. The home server 31 is connected to a management server 32 outside the home via a network N such as the Internet, and is connected to a home device 34 via a signal line 33. The in-home server 31 operates with DC power acquired from the DC distribution board 8 via the DC wiring 35 as a power source. From the management server 32, for example, information related to power sale (reverse power flow) is transmitted to the in-home server 31 via the network N.

  A control box 36 that manages operation control of various devices in the home by network communication is connected to the home server 31 via a signal line 37. The control box 36 is connected to the control unit 7 and the DC distribution board 8 via the signal line 17 and can directly control the DC device 5 via the DC supply line 38. Therefore, the in-home server 31 can output information on the power sale (reverse power flow) to the control unit 7 via the control box 36. The control box 36 is connected to, for example, a gas / water meter 39 that can remotely measure the amount of gas and water used, and an operation panel 40 of the network system 30. The operation panel 40 is connected to a monitoring device 41 including, for example, a door phone slave, a sensor, and a camera.

  When the in-home server 31 inputs an operation command for various devices in the home via the network N, the home server 31 notifies the control box 36 of the instruction, and operates the control box 36 so that the various devices operate in accordance with the operation command. . The in-home server 31 can provide various information acquired from the gas / water meter 39 through the control box 36 to the management server 32 through the network N, and operates that the monitoring device 41 has detected an abnormality. When accepted from the panel 40, this is also provided to the management server 32 through the network N.

Next, a specific configuration of the control unit 7 will be described.
As shown in FIG. 2, the control unit 7 includes a control unit 51, a first DC / DC converter (hereinafter referred to as “first converter”) 55, and a second DC / DC converter (hereinafter referred to as “second converter”). 56), a battery side converter 57, a bidirectional converter 60, a battery 54, and a reverse power detection circuit 50.

The first converter 55 converts the DC power (solar cell power Ppv) input from the solar cell 3 into desired DC power and outputs it to the DC distribution board 8.
Specifically, as shown in FIG. 3, the first converter 55 includes an input voltage detection circuit 61 that detects a voltage on the solar cell 3 side, and an output voltage detection circuit 62 that detects a voltage value on the DC distribution board 8 side. An input current detection circuit 63 that detects a current value on the solar cell 3 side, a power circuit 64 for power conversion, a CPU 65 that controls the power circuit 64, and a nonvolatile memory 65 a that is accessed by the CPU 65. Composed.

  The CPU 65 appropriately controls the power circuit 64 in accordance with a program stored in the memory 65a. Specifically, the MPPT control described in the background art is executed according to the program. From the viewpoint of power generation efficiency of the solar cell 3, it is preferable that MPPT control is always performed.

Based on the control signal from the CPU 65, the power circuit 64 converts the power supplied from the solar cell 3 into a desired power and outputs it to the DC distribution board 8 side. According to the MPPT control, as described with reference to FIG. 7 in the background art, the CPU 65 controls the output power Pout (solar cell power Ppv) to the maximum output power Pmax through the power circuit 64.

  The input voltage and input current of the power circuit 64 are detected by the input voltage detection circuit 61 and the input current detection circuit 63, and the output voltage is detected by the output voltage detection circuit 62. These detection results are output to the CPU 65. Thereby, the CPU 65 determines whether or not the input power is appropriately converted into the output power. The power circuit 64 includes a plurality of switch elements and the like. Further, the CPU 65 receives a command signal related to the output power Pout from the control unit 51.

  The second converter 56 converts the DC power input from the fuel cell 16 into desired DC power and outputs it to the DC distribution board 8. The specific configuration of the second converter 56 is substantially the same as that of the first converter 55 shown in FIG. The difference from the first converter 55 is that, as shown in FIG. 3, in the second converter 56, the power generation rules of the fuel cell 16 are stored in the memory 65a. The power generation rules regulate the maximum output power and prohibit a sudden change in the generated power. By generating power according to this power generation rule, it is possible to extend the life of the fuel cell 16 while increasing the power generation efficiency from the fuel cell 16.

  The battery-side converter 57 and the battery 54 are connected to the DC power line 14 via the battery connection line 53. The battery-side converter 57 converts the power of the DC power line 14 into desired power and charges the battery 54, or converts the power charged in the battery 54 into desired power and discharges it to the DC power line 14. Or The battery side converter 57 is a DC / DC bidirectional converter. The specific configuration of the battery side converter 57 is substantially the same as that of the first converter 55 shown in FIG. 3 except that power can be output in both directions on the battery 54 side and the DC power line 14 side. Further, the battery side converter 57 outputs the detection result of its own input voltage detection circuit 61 to the control unit 51. The control unit 51 can recognize the battery voltage Vb of the battery 54 based on the detection result.

  The bidirectional converter 60 is provided in the cross flow connection line 12. The bidirectional converter 60 includes an AC / DC converter 58 and a DC / AC converter 59. The DC / AC converter 59 converts the DC power from the DC power line 14 into AC power (output current iout) and supplies the AC power to the AC power line 23. The AC / DC converter 58 converts AC power from the AC power line 23 into DC power (output current Iout) and supplies the DC power to the DC power line 14. The AC / DC converter 58 and the DC / AC converter 59 can convert to desired output power. The specific configurations of the AC / DC converter 58 and the DC / AC converter 59 are substantially the same as those of the first converter 55 shown in FIG. 3 except that the power circuit 64 converts power between direct current and alternating current. is there.

  The AC / DC converter 58 is controlled by the control unit 51 and outputs the detection result of the output voltage detection circuit 62 (see FIG. 3) to the control unit 51. The control unit 51 can recognize the voltage V of the DC power line 14 based on the detection result. In this way, by providing the bidirectional converter 60 in the cross flow connection line 12, AC power is converted into DC power and transmitted to the DC power line 14, or DC power is converted into AC power and the AC power line 23. Or send electricity to

  Here, direct-current power generated by the solar cell 3 can be supplied to the DC device 5. Therefore, for example, compared to a system that always converts the generated power of the solar cell 3 into alternating current, power loss related to power conversion can be reduced, and transmission efficiency is good. However, since power generation by the solar cell 3 depends on time and weather, it is difficult to supply stable power to the DC device 5. On the other hand, for AC power, for example, stable power transmission from an AC power source 2 generated by an electric power company can be expected. Therefore, when sufficient power generation by the solar cell 3 cannot be performed, AC power from the AC power source 2 can be converted to DC power and supplied to the DC device 5, so that power can be stably supplied to the DC device 5. Conversely, when it is determined that the amount of power generated by the solar cell 3 exceeds the amount of power used by the DC device 5, the DC power of the solar cell 3 is converted to AC power and supplied to the AC device 6, The power can be sold by causing the AC power source 2, that is, the power company, to reverse the power flow.

  The reverse power detection circuit 50 detects the power supplied to the AC power line 23 between the AC distribution board 11 and the AC power supply 2, particularly the power reversely flowed from the AC distribution board 11 to the AC power supply 2 side. The detection result is output to the control unit 51.

  Based on the detection result from the reverse power detection circuit 50, the control unit 51 recognizes the reverse power and calculates the amount of power Wh by integrating the reverse power with time. Here, as shown in FIG. 1, information about the reverse power is transmitted from the management server 32 to the control unit 7 via the network N, the home server 31 and the control box 36 at predetermined intervals. The control unit 51 receives information on the reverse power flow via the signal line 17. The reverse power flow is not always allowed without limitation. For example, the reverse power flow is prohibited or the amount of power that allows reverse power flow is limited every predetermined period. When reverse power flow is prohibited, it is necessary to prevent reverse power flow. Here, the amount of power for which reverse tide is allowed is the threshold value Wh1. The information about the reverse power includes information such as the threshold value Wh1. The control unit 51 updates information such as the threshold value Wh1 (stores in the memory 51a) every time it receives information on reverse power flow, and thereafter performs control based on the latest information.

  The control unit 51 prohibits the reverse power flow or restricts the power amount Wh allowing the reverse power according to the information. When prohibiting the reverse power flow, the control unit 51 charges the battery 54 with the power corresponding to the power detected through the reverse power detection circuit 50 from the DC power line 14 through the battery-side converter 57. Thereby, the reverse power flow can be prohibited without affecting the voltage V of the DC power line 14. When limiting the amount of power Wh to flow backward, the control unit 51 calculates the amount of power Wh by integrating the power in a predetermined period with time. When the calculated power amount Wh reaches the threshold value Wh1, the control unit 51 charges the battery 54 through the battery-side converter 57 by the amount of power that is reversely flowed in the same manner as described above, so that the reverse flow of power is achieved. Is prohibited. Here, when reverse power is detected through the reverse power detection circuit 50, in other words, during the period from when the power amount Wh reaches the threshold value Wh1 until charging of the battery 54 is started, Although the current is reversed, the amount of power Wh, which is a function of time, is so small that it is negligible because it is very small in time. Note that the threshold value Wh1 may be set small in consideration of the reverse power flow due to this time difference.

  The controller 51 constantly monitors the voltage V of the DC power line 14 through the AC / DC converter 58. Specifically, as shown in FIG. 4A, the control unit 51 includes the voltage V, the first and second threshold values V1 and V2, and the first and second command values stored in its own memory 51a. A1 and A2 are compared.

  For example, when the generated power is larger than the demand power, the voltage V of the DC power line 14 increases. On the other hand, when the generated power is less than the demand power, the voltage V of the DC power line 14 is low. Since there is such a tendency, it is possible to recognize the equilibrium state of the supplied power and the demand power by looking at the voltage V of the DC power line 14. When the voltage V of the DC system power line 14 coincides with the first command value A1, the supplied power and the demand power are in an equilibrium state. Here, the supplied power is a value obtained by adding the power exchanged between the AC and DC power systems to the generated power. The control unit 51 determines that the generated power is greater than the demand power when the voltage V exceeds the first command value A1, and determines that the generated power is less than the demand power when the voltage V is less than the first command value A1. . Then, as shown in FIG. 4B, the control unit 51 increases the output current iout through the DC / AC converter 59 or through the AC / DC converter 58 during the period when the voltage V exceeds the first command value A1. The output current Iout is decreased. Specifically, as shown in FIG. 4B, the output current Iout is reduced through the AC / DC converter 58 during the period T1 when the voltage V exceeds the first command value A1. Here, since the output current Iout does not reach zero, the DC / AC converter 59 does not output the output current iout. In the period T2 when the voltage V exceeds the first command value A1, the output current Iout is decreased through the AC / DC converter 58, and the output current Iout reaches zero. At this time, if the voltage V still exceeds the first command value A1, output of the output current iout is started through the DC / AC converter 59, and the output current iout is continued until the voltage V matches the first command value A1. Is increased. When the voltage V matches the first command value A1, the output current iout is constant. By this control, the voltage V is maintained at the first command value A1.

  During the period in which the voltage V is less than the first command value A1, the output current Iout increases through the AC / DC converter 58 or the output current iout decreases through the DC / AC converter 59. Specifically, during the period T3 when the voltage V is less than the first command value A1, when the output current iout is reduced through the DC / AC converter 59 and the output current iout reaches zero, the AC / DC Output of the output current Iout through the converter 58 is started. The output current Iout of the AC / DC converter 58 is increased until the voltage V matches the first command value A1. When the voltage V coincides with the first command value A1, the output current Iout is constant. By this control, the voltage V is maintained at the first command value A1.

  Thereby, the solar cell 3 and the fuel cell 16 can generate electric power suitable for their own circumstances regardless of the demand electric power. Specifically, the solar cell 3 and the fuel cell 16 can always generate power according to the power generation rules. Here, the power generation rule of the solar cell 3 is executed by MPPT control. Further, the power generation rule corresponds to a control rule.

  The first threshold value V1 is set to a value larger than the first command value A1. The first threshold value V1 is set based on the maximum voltage V that the DC power line 14 can tolerate. When the generated power is larger than the demand power, the voltage V reaches the first threshold value V1 when surplus power cannot be sufficiently supplied to the AC power line 23. As a case where power cannot be sufficiently supplied to the AC power line 23, the power to be transmitted to the AC power line 23 exceeds the maximum output power of the DC / AC converter 59, or the reverse power flow is limited. Is assumed. In this case, the voltage V of the DC power line 14 increases.

  As shown in FIG. 4A, the controller 51 increases the voltage V of the DC power line 14 to the first threshold value V1 (time t1 in FIG. 4A). The output power Pout is suppressed in the order of the two converters 56 and the first converter 55. Thereby, the voltage V of the DC power line 14 becomes less than the first threshold value V1, and an excessive increase in the voltage V is suppressed. Further, by suppressing the output power of the second converter 56 with priority, the power generation efficiency of the solar cell 3 can be maintained while suppressing the fuel consumption of the fuel cell 16.

  The second command value A2 is set smaller than the first command value A1. The second threshold value V2 is set to a value between the first command value A1 and the second command value A2. The second command value A2 is set based on the voltage V of the DC power line 14 when the supply power is insufficient with respect to the demand power of the DC device 5. Here, for example, it can be assumed that AC power from the AC power source 2 cannot be supplied to the DC power line 14 through the AC / DC converter 58 due to a power failure or the like. In such a case, the voltage V of the DC power line 14 is less than the second command value A2. Further, for example, when the demand power of the DC device 5 increases rapidly, the maximum output power of the AC / DC converter 58 is limited, but this cannot be dealt with immediately, and the voltage V becomes the second command value A2. The case where it becomes less than can be assumed. In a state where the voltage V is less than the second command value A2, there is a possibility that power is not sufficiently supplied to the DC device 5 and the DC device 5 does not operate normally. The control unit 51 performs control so that the voltage V matches the first command value A1. Specifically, in the control, when the voltage V of the DC system power line 14 decreases and reaches the second command value A2 (time t3 in FIG. 4A), the power of the battery 54 is reduced through the battery-side converter 57. It is executed by discharging the DC system power line 14. Here, the battery-side converter 57 is stopped until the voltage V reaches a second threshold value V2 that is greater than the second command value A2. Therefore, when the voltage V of the DC system power line 14 is less than the second command value A2, the battery 54 is configured to assist power supply from the AC system power line 23 to the DC system power line 14 through the AC / DC converter 58. Is supplied to the DC power line 14. Thereby, the voltage V of the DC system power line 14 is controlled so as to coincide with the second command value A2. Therefore, the insufficient power can be compensated without affecting the power generation of the solar cell 3 and the fuel cell 16 according to the power generation rule.

  The control unit 51 activates the battery-side converter 57 when the voltage V decreases and reaches the second threshold value V2. Here, the battery-side converter 57 is stopped until the voltage V reaches the second threshold value V2 except when the battery 54 is charged with electric power so as to inhibit the reverse flow of the electric power. In addition, the battery-side converter 57 requires a certain time from the start of startup to the completion of startup that can actually supply power. Considering this, the second threshold value V2 is set. That is, even if there is a sudden voltage drop of the voltage V, when the voltage V reaches the second command value A2, the second threshold value V2 is set so that the start of the battery side converter 57 is completed. Yes. Therefore, when the voltage V reaches the second command value A2 by starting the battery-side converter 57 when the voltage V reaches the second threshold value V2, the control unit 51 (see FIG. 4A). At time t2), power can be supplied to the DC power line 14 through the battery-side converter 57. Thereby, the said insufficient electric power can be compensated more rapidly. Moreover, since the battery side converter 57 is stopped until the voltage V reaches the second threshold value V2, the standby power of the battery side converter 57 can be eliminated.

  Further, the battery-side converter 57 started when the voltage V becomes the second threshold value V2 is stopped again when the voltage V becomes equal to or higher than the first command value A1. Battery-side converter 57 may be stopped again when voltage V becomes equal to or higher than second threshold value V2.

  As shown in FIG. 2, the DC distribution board 8 includes a DC breaker 70 and a pair of DC / DC converters 71. The DC breaker 70 is provided on the DC power line 14 and cuts off the abnormal current when an abnormal current flows through the DC power line 14. This prevents the current from flowing into the DC device 5. The DC / DC converter 71 steps down the power of the DC power line 14 to an appropriate voltage and supplies it to the DC device 5. Here, since the DC breaker 70 does not step down the voltage of the DC system power line 14, it can supply high-voltage power to the DC device 5. In this way, power loss during power transmission can be suppressed by supplying high-voltage power.

  Next, the power supply control processing procedure executed by the control unit 51 will be described with reference to the flowchart of FIG. This flow is executed according to the power supply program stored in the memory 51a. The power supply program is created from the viewpoint of maintaining a balance between the supplied power and the demand power.

  Control for maintaining the voltage V at the first command value A1 is executed (S101). The control is performed through the control of the bidirectional converter 60 as described above. Then, it is determined whether or not the voltage V is equal to or higher than the first threshold value V1 (S102). When it is determined that the voltage V is less than the first threshold value V1 (NO in S102), power generation is performed according to the power generation rules of the solar cell 3 and the fuel cell 16 through both converters 55 and 56 (S103). . Here, the power generation rule of the solar cell 3 is executed through MPPT control. Then, the process proceeds to step S105. On the other hand, when it is determined that the voltage V is equal to or higher than the first threshold value V1 (YES in 102), the output power Pout is suppressed through both converters 55 and 56 (S104). Thereafter, the process proceeds to step S105.

  In step S105, it is determined whether or not the voltage V is equal to or lower than the second threshold value V2. If it is determined that the voltage V is equal to or lower than the second threshold value V2 (YES in S105), and the voltage V is less than the second command value A2, the voltage V is sent through the battery-side converter 57 to the second command value. The value A2 is controlled (S106). This completes the process of the power supply program. On the other hand, when voltage V exceeds second threshold value V2 (NO in S105), in step S107, the power supply program process is terminated while battery-side converter 57 is maintained in the stopped state.

  In this flowchart, step S101 is executed through the bidirectional converter 60, steps S102 to S104 are executed through the first and second converters 55 and 56, and steps S105 to S107 are executed through the battery side converter 57.

  Next, the reverse power flow regulation process procedure executed by the control unit 51 will be described with reference to the flowchart of FIG. The flow is executed in accordance with the reverse flow regulation program stored in the memory 51a. The program is executed separately from the power supply program.

  First, the electric energy Wh is calculated based on the reverse power detected by the reverse power detection circuit 50 (S151). Next, it is determined whether or not the calculated power amount Wh is equal to or greater than a threshold value Wh1 (S152).

  If the amount of power Wh is less than the threshold value Wh1 (NO in S152), the process of the reverse flow restriction program is terminated. Whether or not the electric energy Wh reaches the threshold value Wh1 is monitored by repeating the program every predetermined control period.

  When the power amount Wh becomes equal to or greater than the threshold value Wh1 (YES in S152), in other words, when the reverse power reaches the maximum allowable power amount, the battery 54 converts the power of the DC power line 14 through the battery-side converter 57. Is charged (S153). At this time, power corresponding to the power detected through the reverse power detection circuit 50 is charged to the battery 54 from the DC power line 14 through the battery-side converter 57. Thereby, the reverse power flow after the reverse power reaches the maximum allowable electric energy can be prohibited.

  When the reverse power flow is prohibited, it can be assumed that the threshold value Wh1 is set to zero, and YES is always obtained in step S152, and the process of step S153 is executed.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) Supply voltage and demand power by matching the voltage V of the DC system power line 14 with the first command value A1 through the bidirectional converter 60 so that the voltage V of the DC system power line 14 matches the first command value A1. Can be in an equilibrium state. Therefore, it is not necessary to adjust the generated power of the solar cell 3 and the fuel cell 16 even when an imbalance between the generated power and the demand power occurs. Thereby, irrespective of the demand power of the DC equipment 5, the solar cell 3 and the fuel cell 16 can generate electric power with their own power.

  (2) When the voltage V of the DC system power line 14 becomes equal to or higher than the first threshold value V1, the voltage V is controlled to be less than the first threshold value V1. That is, the control unit 51 suppresses the generated power of the solar cell 3 and the fuel cell 16 through both the converters 55 and 56, and suppresses the increase in the voltage V of the DC system power line 14. Thereby, it is suppressed that overpower generate | occur | produces in the power distribution system 1, and the safety | security of the system 1 can be improved.

  (3) The voltage V is controlled so as to coincide with the second command value A2. Specifically, the control is executed by discharging the power of the battery 54 to the DC system power line 14 when the voltage V of the DC system power line 14 becomes less than the second command value A2. Here, the second command value A2 is set based on the voltage V of the DC power line 14 when the supply power is insufficient with respect to the demand power. As a situation where the voltage V of the DC system power line 14 is less than the second command value A2, there may be a case where power cannot be supplied from the AC system power line 23 to the DC system power line 14 due to, for example, a power failure. Even in this case, the power of the battery 54 is discharged to the DC power line 14 through the battery-side converter 57, so that the voltage V is controlled to match the second command value A2. Thereby, it is possible to supply power to the DC device 5 more stably while maintaining the power generation of the solar cell 3 and the fuel cell 16 according to the power generation rule.

  (4) When the voltage V of the DC power line 14 becomes equal to or lower than the second threshold value V2, the battery side converter 57 is activated. Thus, since the battery-side converter 57 can be stopped until the voltage V of the DC system power line 14 becomes equal to or lower than the second threshold value V2, standby power until startup can be eliminated. Further, by starting the battery side converter 57 before the second command value A2 or less, the battery side converter 57 immediately converts the power of the battery 54 to the DC power line when the second command value A2 or less is reached. 14 can be discharged. Thereby, the shortage of supply power can be compensated more quickly.

  (5) The power flowing backward to the AC power source 2 is adjusted by charging the battery 54. As a result, the power flowing backward can be adjusted without adjusting the generated power of the solar cell 3 and the fuel cell 16. Therefore, the solar cell 3 and the fuel cell 16 can generate electric power suitable for themselves regardless of the reversely flowing power.

  (6) The power of the DC power line 14 is charged to the battery 54 through the battery-side converter 57 by an amount corresponding to the power that flows backward to the AC power source 2. Thereby, a reverse power flow can be prohibited without adjusting the generated power of the solar cell 3 and the fuel cell 16.

  (7) It is possible to determine whether the supply power and the demand power are in an equilibrium state based on the voltage V of the DC power line 14 detected through the battery side converter 57. Furthermore, by controlling charging / discharging of the battery 54 so that the voltage V of the DC power line 14 matches the first command value A1, the supplied power and the demand power can be balanced. As described above, the control unit 51 can easily bring the supply power and the demand power into an equilibrium state through the charge / discharge control of the battery 54. Here, for example, a configuration is conceivable in which the power used by the load device and the power generated by the power generator are received, and based on these, the control unit performs charge / discharge control of the battery power according to a predetermined algorithm stored in itself. . However, compared with this configuration, in this embodiment, communication with a load device or a power generation device is not necessary. Further, since the feedback control is performed only by looking at the voltage V of the DC system power line 14, complicated control relating to the communication can be omitted. Thereby, for example, it is possible to cope with a sudden electric power imbalance due to a sudden solar radiation fluctuation of the solar cell 3 or a sudden load change due to ON / OFF of the DC device 5.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. The power distribution system of this embodiment is different from the first embodiment in that the control unit 51 is omitted and the function is distributed to each of the converters 55 to 59 (more precisely, each CPU 65). Yes. Hereinafter, a description will be given focusing on differences from the first embodiment.

  Each converter 55 to 59 recognizes the voltage V of the DC power line 14 through its own output voltage detection circuit 62 (see FIG. 3). Note that the DC / AC converter 59 includes an input voltage detection circuit (not shown) instead of the output voltage detection circuit 62 in order to detect the voltage V of the DC power line 14. The first converter 55 and the second converter 56 store the first threshold value V1 in their own memory 65a. Then, both converters 55 and 56 suppress their outputs when voltage V reaches first threshold value V1. Further, the AC / DC converter 58 and the DC / AC converter 59 constituting the bidirectional converter 60 store the first command value A1 in its own memory 65a. The AC / DC converter 58 supplies the power of the AC power line 23 to the DC power line 14 when the voltage V is less than the first command value A1. Further, the DC / AC converter 59 supplies the power of the DC power line 14 to the AC power line 23 when the voltage V exceeds the first command value A1. Thus, the voltage V is controlled so as to coincide with the first command value A1 as in the above embodiment.

  The battery-side converter 57 stores the second threshold value V2 and the second command value A2 in its own memory 65a. The battery-side converter 57 starts when the voltage V reaches the second threshold value V2, and discharges the electric power of the battery 54 to the DC power line 14 when the voltage V becomes less than the second command value A2. Control to make V coincide with the second command value A2 is executed.

  Further, the battery-side converter 57 recognizes the threshold value Wh1 included in the information related to the reverse power that is acquired through the signal line 17. Further, the battery side converter 57 calculates the amount of electric power Wh based on the reversely flowed power output from the reverse flow power detection circuit 50. As in the first embodiment, when the electric energy Wh reaches the threshold value Wh1, the battery-side converter 57 charges the battery 54 by an amount corresponding to the reversely oscillated electric power. Prohibit reverse tide.

As mentioned above, according to embodiment described, in addition to the effect of (1)-(7) of 1st Embodiment, there can exist the following effects.
(8) The control unit 51 in the first embodiment can be omitted. Therefore, the control unit 7 can have a simpler configuration and the cost related to the control unit 51 can be suppressed. Each converter 55-58 generates power according to its own power generation rule based on threshold values and command values without communicating with each other. As a result, as in the first embodiment, supply power and demand power are the same. Can be balanced. Moreover, the communication of each converter 55-58 becomes unnecessary, and the process which concerns on it becomes unnecessary. As a result, the power balance state can be realized more quickly. Furthermore, since each converter 55-58 is comprised independently, the update and expansion of a system can be performed easily. Specifically, it is possible to update the system or the like through replacement of the converters 55 to 58 as necessary.

In addition, the battery-side converter 57 can prohibit reverse power flow or limit the amount of power Wh that is reverse power flow, as in the first embodiment.
In addition, the said embodiment can be implemented with the following forms which changed this suitably.

  In the first embodiment, the control unit 51 controls the voltage V through the converters 55 to 59 by the power supply program executed according to the flowchart of FIG. However, the control unit 51 may execute different programs through the converters 55 to 59. In this case, step S101, steps S102 to S104, and S105 to S107 are independent program processing procedures. Specifically, the control unit 51 always performs the process of step S <b> 101 through the bidirectional converter 60. At the same time, the control unit 51 performs the processes of steps S102 to S104 through the converters 55 and 56 at predetermined intervals, and performs the processes of steps S105 to S107 through the battery-side converter 57. In the second embodiment, the bidirectional converter 60, the converters 55 and 56, and the battery-side converter 57 each execute a program according to the above processing procedure.

  In the above embodiment, the power that flows backward by charging the battery 54 is adjusted. However, the electric power flowing in the reverse direction through the discharge of the battery 54 may be adjusted. In this case, for example, the electric power from the battery 54 is supplied to the DC device 5, and the surplus generated power is reversely flowed to increase the reversely flowed power.

  In both the above-described embodiments, when prohibiting reverse power flow, power corresponding to the power detected through the reverse power detection circuit 50 is charged from the DC power line 14 to the battery 54 through the battery-side converter 57. It had been. However, the battery 54 may be charged with a part of the reverse power flow through the reverse power detection circuit 50. In this case, the reverse power flow power can be adjusted arbitrarily.

  In the first embodiment, the control unit 51 calculates the power amount Wh based on the detection result of the reverse power detection circuit 50. However, even if the reverse power detection circuit 50 calculates the power amount Wh. Good. In this case, the reverse power detection circuit 50 calculates the amount of power based on the detected power. Also in the second embodiment, the reverse power detection circuit 50 may calculate the power amount Wh in the same manner.

  In both of the above embodiments, reverse power flow was recognized during a predetermined period. However, it may be a power distribution system 1 in which no reverse power flow is recognized. In this case, the control unit 51 or the battery side converter 57 always prohibits reverse power flow.

  In the first embodiment, the voltage V is recognized by the control unit 51 through the AC / DC converter 58. However, the control unit 51 may recognize the voltage V through another converter, for example, the battery side converter 57. A voltage detection circuit may be provided separately from the converter.

  In both the above embodiments, the fuel cell 16 and the solar cell 3 are provided as the DC power generation device, but the DC power generation device is not limited to this as long as it generates DC power. For example, a storage battery, a wind power generator, or the like may be used. Regarding storage batteries and wind power generators, there are power generation rules suitable for themselves from the viewpoint of power generation efficiency and life. Moreover, you may comprise a direct-current power generator only with the solar cell 3 or the fuel cell 16 only.

In both the above embodiments, the first and second threshold values V1 and V2 and the first and second command values A1 and A2 are set, but the second threshold value V2 and the first and second command values A1 are set. , A2 may be omitted. Even in this case, the supply voltage and the demand power are balanced by controlling the voltage V to the first command value A1. Further, for example, it is possible to omit only the first threshold value V1 or only the second threshold value V2. Further, the second threshold value V2 and the second command value A2 may be omitted.
In both the above embodiments, the battery 54, the battery side converter 57, and the reverse power detection circuit 50 are provided, but these may be omitted. Even in this case, the power demand and the supply power can be balanced by transferring power between the AC power line 23 and the DC power line 14 through the bidirectional converter 60.

  (Supplementary note 1) A power distribution system includes a DC power system in which DC power generated by a DC power generator is supplied to a DC load via a DC wiring, and is linked to the DC power system, from an AC power source via an AC wiring. In a power distribution system comprising an AC power system to which AC power is supplied, a bidirectional converter that converts AC power from the AC wiring into DC power, DC power from the DC wiring into AC power, and the DC wiring The DC power input from the DC power generator is set as the maximum output power by controlling the output voltage of the DC power generator to the maximum output voltage that maximizes the DC power generated by the DC power generator. A DC / DC converter to be supplied to the load, voltage detection means for detecting the voltage of the DC wiring, and the voltage so that the voltage of the DC wiring becomes the first command value. By controlling the bi-directional converter comprises a power supplied to the DC line, and a control unit to achieve a balance needs to be power demand through the DC wiring.
  According to the above power distribution system, the supply power and the demand power of the DC load are balanced by transferring power between the AC and DC power systems so that the voltage of the DC wiring matches the first command value. Can do. In other words, when the voltage of the DC wiring coincides with the first command value, the supplied power and the demand power are in an equilibrium state. Therefore, it is not necessary to adjust the generated power of the DC power generator even when an imbalance between the generated power and the demand power of the DC power generator occurs. As a result, the DC power generation device can generate electric power with its own power regardless of the demand power of the DC load.
  (Supplementary note 2) In the power distribution system according to supplementary note 1, when the control unit has a voltage of the DC wiring detected through the voltage detection unit becomes equal to or greater than a first threshold value greater than the first command value, The generated power of the DC power generation device is suppressed through control of the DC / DC converter, and the voltage of the DC wiring is controlled to be less than a first threshold value.
  For example, if the power to be supplied from the DC wiring to the AC wiring to maintain the power balance exceeds the maximum output power of the bidirectional converter, or if the reverse power flow is limited, the DC wiring is sufficient. Power cannot be supplied to AC wiring. Therefore, the voltage of the DC wiring rises. In the power distribution system, when the voltage of the DC wiring becomes equal to or higher than the first threshold value, the voltage is controlled to be lower than the first threshold value. That is, the control unit suppresses the generated power of the DC power generator through the DC / DC converter, and suppresses the increase in the voltage of the DC wiring. Thereby, generation | occurrence | production of overpower in a power distribution system is suppressed, and the safety | security of the system can be improved.
  (Supplementary note 3) In the power distribution system according to supplementary note 1 or 2, the battery connected to the DC wiring, and provided between the DC wiring and the battery, and the battery is charged with electric power of the DC wiring, and the battery A charge / discharge circuit for discharging the electric power of the DC wiring to the DC wiring, and the control unit is configured such that the voltage of the DC wiring detected through the voltage detecting means is less than a second command value smaller than the first command value. When this happens, the charge / discharge circuit is controlled so as to make the voltage of the DC wiring coincide with the second command value.
  According to the power distribution system, the voltage is controlled to match the second command value. Specifically, the control is executed by discharging the battery power to the DC wiring when the voltage of the DC wiring becomes less than the second command value. Here, the second command value is set based on the voltage of the DC wiring when the supply power is insufficient with respect to the demand power of the DC load. As a situation where the voltage of the DC wiring is less than the second command value, for example, a case where power cannot be supplied from the AC wiring to the DC wiring due to a power failure or the like can be considered. As described above, when the voltage of the DC wiring is less than the second command value, the battery is controlled through the charge / discharge circuit so that the voltage of the DC wiring matches the second command value. As a result, it is possible to supply power more stably to the DC load while maintaining power generation suitable for the DC power generator itself.
  (Supplementary note 4) In the power distribution system according to supplementary note 3, the control unit sets the voltage of the DC wiring detected through the voltage detection means to a value between the first command value and the second command value. When the threshold value becomes 2 or less, the charge / discharge circuit is activated.
  According to the power distribution system, the charge / discharge circuit is activated when the voltage of the DC wiring becomes equal to or lower than the second threshold value. Thus, since the charge / discharge circuit can be stopped until the voltage of the DC wiring becomes equal to or lower than the second threshold value, standby power of the charge / discharge circuit until the start can be eliminated. In addition, by starting the charge / discharge circuit before the second command value or less, when the second command value or less is reached, the charge / discharge circuit immediately converts AC power from the AC power system to DC power. This can be supplied to the DC wiring. Thereby, the shortage of the electric power supplied to the DC load can be compensated more quickly. As described above, in the charge / discharge circuit, it is possible to achieve both follow-up controllability against voltage drop and reduction in power consumption.
  (Supplementary Note 5) In the power distribution system according to Supplementary Note 3 or 4, the power distribution system includes a reverse power detection circuit that detects power that is connected to the AC wiring and reversely flows to the AC power supply, and the control unit includes: Based on the detection result of the reverse power detection circuit, the reverse power is adjusted by charging / discharging the battery through the charge / discharge circuit.
  For example, when the generated power exceeds the demand power, the DC power is supplied to the AC wiring through the bidirectional converter. At this time, the power may flow back to the AC power source for power sales. Here, the reverse power flow is not always recognized without limitation. For example, the reverse power flow is prohibited or the amount of power that allows the reverse power flow is limited every predetermined period. According to the said structure, the electric power which flows backward is adjusted by charging / discharging of a battery. Thereby, the electric power which flows backward can be adjusted, without adjusting the electric power generated by the DC power generator. Therefore, the DC power generator can generate electric power suitable for itself regardless of the reversely flowing power.
  (Supplementary note 6) In the power distribution system according to supplementary note 5, the control unit supplies the power of the DC wiring through the charge / discharge circuit by an amount corresponding to the reverse flow power detected by the reverse power detection circuit. Charge the battery to prevent reverse power flow.
  According to the above power distribution system, the power of the DC wiring is charged to the battery through the charge / discharge circuit by the amount corresponding to the reversely flowed power. Thereby, a reverse power flow can be prevented without adjusting the generated power of the DC power generator.
  (Supplementary note 7) In the power distribution system according to any one of supplementary notes 3 to 6, the control unit is provided in a distributed manner in the DC / DC converter, the bidirectional converter, and the charge / discharge circuit, and the charge / discharge The circuit stores the second command value, and performs charge / discharge control of the battery so as to coincide with the second command value when the voltage of the DC wiring becomes less than the second command value, The DC / DC converter stores the first threshold value, and when the voltage becomes equal to or higher than the first threshold value, the output voltage is set so that the voltage of the DC wiring is less than the first threshold value. The bidirectional converter stores the first command value, and when the voltage deviates from the first command value, the voltage of the DC wiring matches the first command value. DC wiring and AC And controls the output power to the line.
  According to the power distribution system, the control unit is distributed and provided in each converter. Therefore, each converter independently controls the voltage of the DC wiring through the comparison of the voltage of the DC wiring and the command value or threshold value stored in each converter. Thus, each converter can balance supply power and demand power without communicating with other converters.

  DESCRIPTION OF SYMBOLS 1 ... Power distribution system, 2 ... AC power supply (AC power supply), 3 ... Solar cell (DC power generation device), 7 ... Control unit, 12 ... Cross flow connection line, 13-15 ... DC system power line (DC wiring), 16 ... Fuel cell (DC generator), 18, 19 ... DC power line, 50 ... reverse power detection circuit, 51 ... control unit, 51a ... memory, 54 ... battery, 55 ... first converter, 56 ... second converter, 57 ... battery side converter (charge / discharge circuit), 58 ... AC / DC converter (voltage detection means), 59 ... DC / AC converter, 60 ... bidirectional converter, 61 ... input voltage detection circuit, 62 ... output voltage detection circuit, 63 ... Input current detection circuit, 64 ... Power circuit, 65 ... CPU.

Claims (5)

A DC power system in which DC power generated by a DC generator that generates maximum DC power when the operating voltage is the maximum output voltage is supplied to a DC load via a DC wiring;
An AC power system that is linked to the DC power system and is supplied with AC power from an AC power source through AC wiring ,
A bidirectional converter for converting converts AC power supplied from the AC wiring to the DC power, the DC power supplied from the DC line to AC power,
The DC power generator is connected to the DC wiring, and the DC power generator is configured to generate the maximum DC power by controlling the output power so that the operating voltage of the DC power generator becomes the maximum output voltage. A DC / DC converter for supplying the direct- current power to the direct-current load;
Voltage detecting means for detecting the voltage of the DC wiring;
A battery connected to the DC wiring;
A charge / discharge circuit that is provided between the DC wiring and the battery, charges the battery with the power of the DC wiring, and discharges the power of the battery to the DC wiring;
The bidirectional converter, the DC / DC converter, and a control unit that controls the charge / discharge circuit,
The voltage of the DC wiring when the supply power, which is the power supplied by the DC wiring, and the demand power, which is the power required by the DC load, is a first command value, and from the first command value, A smaller voltage is the second command value, and a second threshold value is set between the first command value and the second command value,
The controller is
When the voltage of the DC wiring detected by the voltage detection means is larger than the second threshold value, the DC power generator controls the DC / DC converter so as to generate the maximum DC power. And controlling the bidirectional converter so that the voltage of the DC wiring becomes the first command value,
When the voltage of the DC wiring detected by the voltage detection means is equal to or lower than the second threshold value, the charge / discharge circuit is activated so that the DC power generator generates the maximum DC power. Controlling the DC / DC converter, controlling the bidirectional converter so that the voltage of the DC wiring becomes the first command value,
If the voltage of the DC wiring detected by the voltage detection means is less than the second command value, the DC power generator controls the DC / DC converter so as to generate the maximum DC power; The bidirectional converter and the charge / discharge circuit are controlled so that the voltage of the DC wiring becomes the second command value.
Power distribution system.   When the voltage of the DC wiring detected by the voltage detection means is a voltage equal to or higher than a first threshold value that is larger than the first command value, the control unit determines that the voltage of the DC wiring is the first threshold. The DC / DC converter suppresses the power generated by the DC power generator so that the voltage is less than the value.
  The power distribution system according to claim 1.   A reverse power detection circuit that is connected to the AC wiring and detects power flowing backward to the AC power supply;
  The control unit controls the charge / discharge circuit based on the detection result of the reverse power detection circuit, and adjusts the power flowing backward to the AC power source by charging / discharging of the battery accompanying the control.
  The power distribution system according to claim 1.   The control unit prevents the reverse power flow by controlling the charge / discharge circuit so that power corresponding to the power detected by the reverse power detection circuit is charged from the DC wiring to the battery.
  The power distribution system according to claim 3.   The function of the control unit is distributed to the DC / DC converter, the bidirectional converter, and the charge / discharge circuit,
  The charging / discharging circuit stores the second command value, and when the voltage of the DC wiring is less than the second command value, the battery is set so that the voltage of the DC wiring becomes the second command value. Control the charge and discharge of
  The DC / DC converter stores the first threshold value. When the voltage of the DC wiring is equal to or higher than the first threshold value, the voltage of the DC wiring is less than the first threshold value. Control the output power to become voltage,
  The bidirectional converter stores the first command value, and when the voltage of the DC wiring is out of the first command value, the DC wiring is set so that the voltage of the DC wiring becomes the first command value. The power output to the
  The power distribution system according to claim 2, claim 3 quoting claim 2, or claim 4 quoting claim 3 thereof.

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