WO2011058412A1

WO2011058412A1 - Power distribution system

Info

Publication number: WO2011058412A1
Application number: PCT/IB2010/002843
Authority: WO
Inventors: 晃吉武; 小新　博昭; ▲祐▼輔岩松
Original assignee: パナソニック電工株式会社
Priority date: 2009-11-16
Filing date: 2010-11-09
Publication date: 2011-05-19
Also published as: JP2011109783A; JP5799254B2

Abstract

Disclosed is a power distribution system equipped with a DC electric power system in which DC electric power generated by a DC electricity generation device is supplied to a DC load via a DC supply line, and an AC power system which is hooked up to the DC electric power system and in which AC electric power from an AC power supply is supplied via an AC supply line. The power distribution system is equipped with: a two-way converter which converts the AC electric power from the AC supply line to DC electric power, and the DC electric power from the DC supply line to AC electric power; and a control unit which promotes a balance between the electric power supply to the DC supply line and the electric power demand required via the DC supply line by controlling the two-way converter so that the DC supply line voltage reaches a reference value.

Description

Specification Power Distribution System Technical Field

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

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 popular 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, the solar cell 1 01 that converts light energy from the sun into electric energy (DC power) and the DC power generated by the solar cell 1 01 are appropriate. Converter 103 that converts the output voltage to V out and supplies power to the load, the fuel cell 10 02 that generates electricity by the chemical reaction of the substance, and the DC power generated by the fuel cell 10 02 And a converter 104 for supplying electric power to the load, and a DC load 105 that operates with 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 greatly varies depending on the operating voltage. If the operating voltage of the solar cell 101 can be controlled by the comparator 103 to operate at Vmp, the maximum output power Pm ax can be output from the solar cell 101 and the solar cell 101 can be used efficiently. Will be. The control for outputting the output power from the solar cell 101 at Pmax and using the solar cell 101 to the maximum is called maximum output operating point tracking control (hereinafter referred to as MPPT control).

Fuel cell 102 also has power generation rules that are suitable for itself. In the power generation rules, for example, the maximum output power is specified, or a sudden change in 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, DC power generation devices such as the solar cell 101 and the fuel cell 102 have an actual advantage of generating electric power according to the respective circumstances such as the power generation rule and MP PT control.

In addition, as shown in Patent Document 2, for example, 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 generator is low.

[Patent Document 1] Japan Patent Publication 232674

[Patent Document 2] Japan Patent Publication 1 59730 By the way, in the power distribution system shown in the above-mentioned Patent Document 1, the power generated by the solar cell 1001 and the fuel cell 102 and the power consumed by the DC load 105 are lost in various power conversion devices. If the power loss is ignored, the power is the same. In other words, the power supplied in the DC distribution system is determined by the power consumption of the DC load 105. In other words, even when the power generation capacity of the solar cell 10 1 and the fuel cell 10 2 can exceed the power consumption, only the power consumption of the DC load 10 5 can be generated, resulting in inefficient operation. . On the other hand, if the power consumption exceeds the power generation according to the MPPT control and power generation rules of the solar cell 10 1 and the fuel cell 10 2, for example, the above power generation rule is violated from the fuel cell 10 2. Output power. However, this is not preferable in terms of power generation efficiency and lifetime of the fuel cell 102 as described above.

In this way, in DC power generation devices such as solar cell 101 and fuel cell 1002, depending on the power consumption (demand power) of DC load 105, there is a risk that power generation according to MPPT control and power generation rules may not be possible. There is. Summary of the Invention

The present invention has been made in view of such circumstances, and provides a power distribution system capable of generating power suitable for itself in a DC power generator regardless of the demand power of a DC load.

According to an embodiment of the present invention, 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 linked to the DC power system, an AC power source An AC power system that is supplied with AC power via wiring, wherein the power distribution system converts AC power from the AC wiring to DC power, and DC power from the DC wiring to AC power. By controlling the bidirectional converter so that the voltage of the DC wiring becomes a reference value, the power supplied to the DC wiring and the demand power required through the DC wiring And a control unit for balancing.

Also, the DC power connected to the DC wiring and input from the DC power generator is converted into desired DC power according to a predetermined control rule stored in itself, and the converted DC power is supplied to the DC load. A DCZDC converter to be supplied; and voltage detection means for detecting the voltage of the DC wiring; and the control unit controls the bidirectional converter so that the voltage of the DC wiring detected through the voltage detection means becomes a reference value. By doing so, the supply power to the DC wiring and the demand power required through the DC wiring may be balanced.

According to the above configuration, the supply power and the demand power of the DC load can be balanced by transferring power between the AC and DC power systems so that the voltage of the DC wiring matches the reference value. . In other words, when the DC wiring voltage matches the reference value, the supply power and the demand power are in equilibrium. Therefore, it is not necessary to adjust the generated power of the DC power generator even if an imbalance between the generated power and the demand power of the DC power generator occurs. As a result, regardless of the demand power of the DC load, the DC power generator can generate power with its own appropriate power. In addition, the control unit suppresses the generated power of the DC power generation device through the control of the DCDC converter when the voltage of the DC wiring detected through the voltage detection means becomes an upper limit value greater than the reference value. Then, the DC wiring voltage may be controlled to be less than the upper limit 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 embodiment of the present invention, when the voltage of the DC wiring becomes equal to or higher than the upper limit value, the voltage is controlled to be less than the upper limit value. In other words, the control unit suppresses the power generated by the DC power generator through the DCZ DC converter, and suppresses the voltage rise of the DC wiring. As a result, the occurrence of overpower in the distribution system is suppressed, and the safety of the system can be improved.

A battery connected to the direct current wiring; and charging / discharging between the direct current wiring and the battery, charging the battery with electric power of the direct current wiring, and discharging the electric power of the battery to the direct current wiring. And the control unit matches the voltage of the DC wiring with the lower limit value when the voltage of the DC wiring detected through the voltage detection means is less than a lower limit value smaller than the reference value. The charge / discharge circuit may be controlled to achieve this.

According to the above configuration, the voltage is controlled to match the lower limit value. Specifically, this control is executed by discharging the battery power to the DC wiring when the voltage of the DC wiring becomes less than the lower limit. Here, the lower limit 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 lower limit value, for example, power may not be supplied from the AC wiring to the DC wiring due to a power failure or the like. Thus, when the voltage of the DC wiring is less than the lower limit value, the battery is controlled through the charge / discharge circuit so that the voltage of the DC wiring matches the lower limit 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.

In addition, the control unit starts the charge / discharge circuit when the voltage of the DC wiring detected through the voltage detection unit becomes equal to or lower than a threshold value set to a value between the reference value and the lower limit value. It may be moved.

According to the above configuration, the charging / discharging circuit is activated when the voltage of the DC wiring falls below the threshold value. In this way, the charging / discharging circuit can be stopped until the voltage of the DC wiring is equal to or lower than the threshold value, so that the standby power of the charging / discharging circuit until the start-up can be eliminated. In addition, by starting the charge / discharge circuit before it becomes less than the lower limit value, when the charge / discharge circuit becomes less than the lower limit value, the charge / discharge circuit immediately converts AC power from the AC power system into DC power, Can be supplied to the DC wiring. As a result, the shortage of power supplied to the DC load can be compensated more quickly. As described above, in the charge / discharge circuit, follow-up controllability against voltage drop and reduction of power consumption Can be made compatible.

And a reverse power detection circuit that is connected to the AC wiring and detects power flowing backward to the AC power source, and the control unit is based on a detection result of the reverse power detection circuit. The reverse power flow may be adjusted by charging / discharging the battery through the charging / discharging circuit.

For example, when the generated power exceeds the demand power, DC power is supplied to the AC wiring through the bidirectional converter. At this time, the power may flow backward to the AC power supply for power sales. Here, 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 the reverse power flow is limited for each predetermined period. According to the said structure, the electric power which flows backward is adjusted by charging / discharging of a battery. This makes it possible to adjust the reverse power flow without adjusting the power generated by the DC power generator. Therefore, the DC power generator can generate appropriate power for itself regardless of the reverse power flow.

Further, the control unit prevents the reverse power flow by charging the battery with the power of the DC wiring by an amount corresponding to the reverse power detected by the reverse power detection circuit, through the charge / discharge circuit. You may do it.

According to the above configuration, the DC wiring power is charged to the battery through the charging / discharging circuit by the amount corresponding to the reverse power flow. As a result, reverse power flow can be prevented without adjusting the power generated by the DC power generator.

The control unit is provided in a distributed manner in the DC / DC converter, the bidirectional converter and the charge / discharge circuit, the charge / discharge circuit stores the lower limit value, and the voltage of the DC wiring is When the battery becomes less than the lower limit, the battery is charged and discharged so as to match the lower limit. The DC / DC converter stores the upper limit and the voltage becomes equal to or higher than the upper limit. When the output voltage is controlled so that the voltage of the DC wiring is less than the upper limit value, the bidirectional converter stores the reference value, and when the voltage deviates from the reference value, the DC wiring The output power to the direct current wiring and the alternating current wiring may be controlled so that the voltage of the current matches the reference value.

According to the above configuration, 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. In this way, each converter can balance supply power and demand power without communicating with other converters. The invention's effect

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.

Brief Description of Drawings The objects and features of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a configuration of a power distribution system according to a first embodiment of the present invention.

FIG. 2 is an enlarged block diagram of a part of FIG. 1 in the first embodiment.

FIG. 3 is a block diagram showing a configuration of converters 5 5 to 5 9 in the first embodiment. FIG. 4 (a) in the first embodiment is a graph showing the transition of the first and second threshold values, the first and second command values, and the voltage V; (b) is the first command value and The graph which shows transition of voltage V.

5A is a flowchart showing a processing procedure of a power feeding program in the first embodiment, and FIG. 5B is a flowchart showing a processing procedure of a reverse power flow regulation program.

FIG. 6 is an enlarged block diagram of a part of FIG. 1 in the second embodiment of the present invention.

FIG. 7 is a graph showing the solar cell voltage vs. solar cell power characteristics.

FIG. 8 is a block diagram showing a configuration of a conventional power distribution system. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which form a part of this specification. In the drawings, the same or similar parts are denoted by the same reference numerals, and the description thereof is omitted.

(First embodiment)

Hereinafter, a first embodiment embodying a power distribution system according to the present invention will be described with reference to FIGS. 1 to 6.

As shown in Fig. 1, the home is provided with a power distribution system 1 that supplies power to various devices installed in the home (lighting devices, air conditioners, home appliances, audiovisual devices, etc.). In addition to the power from the commercial AC power supply (AC power supply) 2 for home use, the power distribution system 1 also provides various types of power for the solar cells 3 that are generated by sunlight and fuel cells 16 that are generated by chemical reactions of substances. Supply to the equipment. In addition, the power distribution system 1 supplies power not only to the DC device 5 that operates by inputting DC power (DC power) but also to the AC device 6 that operates by inputting AC power (AC power).

The power distribution system 1 is provided with a control unit 7 and a DC distribution board 8 (with built-in DC breaker). Further, 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.

The control unit 7 is connected to an AC distribution board 11 1 for branching an AC power supply through a cross flow connecting line 12. In addition, an AC power source 2 and an AC device 6 are connected to the AC distribution board 11 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 takes in 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. And the control unit 7 Electric power is output 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. The control unit 7 also exchanges data with the DC distribution board 8 through 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 1 8 or the DC power line 1 9 Or output to relay unit 10 via. Further, the DC distribution board 8 exchanges data with the control unit 9 via the signal line 44 and exchanges data with the relay unit 10 via 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 wires. The DC supply line 22 is a so-called power line carrier communication that superimposes a communication signal for transmitting data by a high-frequency carrier wave on a DC voltage that serves as a power source for DC equipment. Transport to device 5. The control unit 9 acquires the DC power supply of the DC device 5 via the DC power line 1 8 and what DC device 5 is used based on the operation command obtained from the DC distribution board 8 via the signal line 44. Know what to control. Then, the control unit 9 outputs a DC voltage and an operation command to the instructed DC device 5 via the DC supply line 22 to control the operation of the DC device 5.

The control unit 9 is connected via a DC supply line 22 to a switch 43 that is operated when switching the operation of the DC device 5 in the house. In addition, a sensor 24 that detects, for example, a radio wave transmitted from an infrared ray remote controller 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 and the DC device 5 is controlled.

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 through the DC power line 19 and determines which DC device 5 is based on the operation command obtained from the DC distribution board 8 through the signal line 45. Know what to do. Then, 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 the built-in relay for the instructed DC device 5. Also, the relay unit 10 is connected to a plurality of switches 46 for manual operation of the DC device 5, and the power supply to the DC power line 25 is turned on and off by the relay by the operation of the switch 46. By doing so, the DC device 5 is controlled.

For example, a wall outlet or a floor outlet is connected to the DC distribution board 8 through a DC power line 28. If a DC device plug (not shown) is inserted into this DC outlet 27, DC power can be supplied directly to the device. Is possible.

Between the AC distribution board 1 1 and the AC power supply 2, a power meter 29 that can remotely measure the usage of the AC power supply 2 is connected. The power meter 29 is equipped not only with the function of remote meter reading of commercial power consumption, but also with functions such as power line carrier communication and wireless communication. The power meter 29 transmits the meter reading result to the 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 the home equipment 3 4 via a signal line 33. The in-home server 3 1 operates using DC power acquired from the DC distribution board 8 via the DC wiring 35 as a power source. From the management server 3 2, for example, information on power sale (reverse power flow) is transmitted to the in-home server 3 1 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. Also connected to the control box 36 is a gas / water meter 39 that can remotely measure the amount of gas used or the amount of water, for example, 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 unit, a sensor, and a camera.

When the home server 3 1 inputs operation commands for various devices in the home via the network N, the control box 3 sends notifications to the control box 3 6 so that the various devices operate according to the operation commands. Operate 6. In addition, the in-home server 3 1 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, as well as the monitoring device 41. When an error is detected from the operation panel 40, this is also provided to the management server 32 via 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”) 5 5, and a second DCDC converter (hereinafter referred to as “first converter”). (Referred to as “second converter”) 5 6, battery-side converter 5 7, bidirectional converter 60, battery 54, and reverse power detection circuit 50.

The first converter 55 converts the DC power (solar cell power P pv) 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 the voltage on the solar cell 3 side, and an output voltage detection that detects the voltage value on the DC distribution board 8 side. A circuit 62, an input current detection circuit 63 for detecting the current value on the solar cell 3 side, a power circuit 64 for power conversion, a CPU 65 for controlling the power circuit 64, and a nonvolatile memory accessed by the CPU 65 It consists of memory 65a.

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 according to the power generation rule. From the viewpoint of the power generation efficiency of the solar cell 3, it is preferable that the 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 desired power and outputs it to the DC distribution board 8 side. According to the MP PT control, as described with reference to FIG. 7 in the above background technology, the CPU 65 outputs the maximum output power P out (solar cell power P pv) through the circuit 64. Control to electric power PmaX.

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. As a result, 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. In addition, the CPU 65 inputs a command signal related to the output power Pout from the control unit 51.

Second converter 56 converts the DC power input from fuel cell 16 to the desired DC power and outputs it to DC distribution board 8. The specific configuration of second converter 56 is substantially the same as that of 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. Power generation rules stipulate maximum output power or prohibit sudden changes in generated power. By generating power in accordance with this power generation rule, it is possible to extend the life of the fuel cell 16 while improving 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 through 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 converts it into the DC power line 14 To discharge. 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 comparator 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.

Bidirectional converter 60 is provided in cross flow connection line 12. Bidirectional converter 6 0 consists of an ACDC converter 58 and a DCAC 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 it to the AC power line 23. The ACZDC converter 58 converts AC power from the AC power line 23 into DC power (output current I out) and supplies it to the DC power line 14. The AC / DC converter 58 and the DC / AC converter 59 can convert input power 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.

ACZDC converter 58 is controlled by control unit 51 and outputs the detection result of output voltage detection circuit 62 (see FIG. 3) to control unit 51. The control unit 51 can recognize the voltage V of the DC power line 14 based on the detection result. Thus, 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 AC. Power can be transmitted to the power line 23.

Here, the DC 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 power generated by the solar cell 3 into alternating current, the power loss associated with power conversion can be reduced, and the power 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 a 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 into 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 solar cell 3 exceeds the amount of power used by DC device 5, the DC power of solar cell 3 is converted to AC power and supplied to AC device 6. In other words, the power can be sold by making the AC power supply 2, that is, the power company, reverse power flow.

The reverse power detection circuit 50 detects the power supplied to the AC power line 23 between the AC distribution board 1 1 and the AC power supply 2, especially the reverse power flow from the AC distribution board 11 to the AC power supply 2 side. To detect. 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 on the reverse power flow is transmitted from the management server 32 to the control unit via the network N, the home server 31 and the control box 36 every predetermined period. The control unit 51 receives information on this reverse power 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 for each predetermined period. When reverse power flow is prohibited, it is necessary to prevent reverse power flow. Here, the threshold value Wh 1 is the amount of power that allows reverse tide. For information on reverse power, see Information such as Wh 1 is included. The control unit 51 updates the information such as the threshold value Wh 1 every time it receives information on the reverse power flow (stored in the memory 51a), and thereafter performs control based on the latest information.

Based on the above information, the control unit 51 prohibits the reverse power flow or limits the power amount Wh that allows the reverse power flow. When prohibiting the reverse power flow, the control unit 51 charges the battery 54 from the DC power line 14 to the battery 54 through the battery-side converter 5 7 by the amount corresponding to the power detected through the reverse power detection circuit 50. . As a result, the reverse power flow can be prohibited without affecting the voltage V of the DC power line 14. When limiting the amount of electric power Wh flowing backward, the control unit 51 calculates the electric energy Wh by integrating the electric power within a predetermined period with time. Then, when the calculated power amount Wh reaches the threshold value Wh 1, the control unit 51 charges the battery 54 through the battery-side converter 57 by the amount of power reversely flowed in the same manner as described above. Prohibit reverse tide. Here, when reverse power is detected through the reverse power detection circuit 50, in other words, the period from when the amount of power Wh reaches the threshold value Wh 1 until charging of the battery 54 is started. However, the amount of power Wh, which is a function of time, is so small that it can be ignored. In consideration of the reverse power due to this time difference, the threshold Wh 1 may be set smaller than the allowable reverse power.

The control unit 51 constantly monitors the voltage V of the DC power line 14 through the ACZDC converter 58. Specifically, as shown in FIG. 4 (a), the control unit 51 controls the voltage V and the first and second threshold values V 1 and V 2 and the first and second threshold values stored in its own memory 51a. 2 Compare command values A 1 and A 2.

For example, when the generated power is greater 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. Because of this tendency, it is possible to recognize the equilibrium state of supplied power and demand power by looking at the voltage V of the DC power line 14. When the voltage V of the DC power line 14 matches the first command value (reference value) A1, the supply power and demand power are in equilibrium. 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 supplied power is greater than the demand power when the voltage V exceeds the first command value A1, and determines that the supply power is less than the demand power when the voltage V is less than the first command value A1. to decide. Then, as shown in FIG. 4 (b), the controller 51 increases the output current iout through the DCZAC converter 59 during the period when the voltage V exceeds the first command value A1, or the ACZ DC converter. Reduce output current I out through 58. Specifically, as shown in FIG. 4 (b), the output current Iout is reduced through the AC / DC comparator 58 during the period T1 when the voltage V exceeds the first command value A1. Here, since the output current Iout has not reached zero, the DC / AC converter 59 does not output the output current iout. In the period T 2 during which the voltage V exceeds the first command value A 1, the output current I out is decreased through the AC / DC converter 58 and the output current I out 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 is continued until the voltage V matches the first command value A1. ίout is increased. The output current iout is constant when the voltage V matches the first command value A1. With this control, the voltage V is controlled to coincide with the first command value A1.

During the period in which the voltage V is less than the first command value A1, the output current l o u t increases through the ACZDC converter 58 or the output current i o u t decreases through the DCZAC converter 59. Specifically, during the period T3 when the voltage V is less than the first command value A1, the output current iout is reduced through the DCZAC comparator 59 and the output current iout reaches zero. Output of output current I out through converter 58 is started. The output current Iout of the ACZDC converter 58 is increased until the voltage V matches the first command value A1. When the voltage V matches the first command value A1, the output current Iout is constant. With this control, the voltage V is controlled to coincide with the first command value A1.

As a result, the solar cell 3 and the fuel cell 16 can generate electric power according to their own circumstances regardless of the demand power. Specifically, the solar cell 3 and the fuel cell 16 can always generate power in accordance with the power generation rules. Here, the power generation rule of the solar cell 3 is executed by MPPT control. Power generation rules are equivalent to control rules.

The first threshold value (upper limit value) V 1 is set to a value larger than the first command value A 1. The first threshold value V 1 is set based on the maximum voltage V that can be allowed by the DC power line 14. In addition, when the generated power is greater than the demand power, the voltage V reaches the first threshold value V 1 when the surplus power cannot be sufficiently supplied to the AC power line 23. Cases where it is not possible to sufficiently supply the AC power line 23 include when the power to be transmitted to the AC power line 23 exceeds the maximum output power of the DCZA C converter 59 or when 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. 4 (a), the controller 51 increases the voltage V of the DC power line 14 and reaches the first threshold value V 1 (time t 1 in Fig. 4 (a)). Suppresses the output power P out in the order of the second converter 56 and the first converter 55. As a result, the voltage V of the DC power line 14 becomes less than the first threshold value V 1, and an excessive increase in the voltage V is suppressed. Further, by preferentially suppressing the output power of the second converter 56, it is possible to maintain the power generation efficiency of the solar cell 3 while suppressing the fuel consumption of the fuel cell 16.

Second command value (lower limit) A2 is set smaller than the first command value A1. The second threshold value (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 equipment 5. Here, for example, it may 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. Also, for example For example, when the power demand of DC equipment 5 suddenly increases, the maximum output power of the A CZ DC comparator 58 is limited, but this cannot be handled immediately, and the voltage V is the second command value. It can be assumed that the value is less than A2. In the state where the voltage V is less than the second command value A2, there is a possibility that the DC device 5 is not supplied with sufficient power and the DC device 5 does not operate normally. The control unit 51 controls so that the voltage V matches the first command value A1. Specifically, in this control, when the voltage V of the DC power line 14 decreases and reaches the second command value A 2 (time t 3 in FIG. 4 (a)), the battery side converter 5 7 It is executed by discharging the power of battery 5 4 to DC power line 14. Here, the battery-side converter 57 is stopped until the voltage V reaches the second threshold value V2, which is larger than the second command value A2.

Further, 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 5 7 stops until the voltage V reaches the second threshold value V 2 except when the battery 54 is charged with power to inhibit the reverse power flow. Yes. In addition, the battery-side converter 57 requires a certain time from the start of start to the start of actual power supply. Considering this, the second threshold value V 2 is set. That is, even if there is a sudden voltage drop of voltage V, when the voltage V reaches the second command value A 2, the second threshold V 2 is set so that the start of the battery side converter 57 is completed. Is set. 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 (Fig. 4 At time t 3) of (a), power can be supplied to the DC power line 14 through the battery-side converter 5 7. As a result, the above shortage of electric power can be compensated more quickly. Further, since battery-side converter 57 is stopped until voltage V reaches second threshold value V2, standby power of battery-side converter 57 can be eliminated.

Therefore, when the voltage V of the DC power line 14 is less than the second command value A 2, the power supply from the AC power line 23 to the DC power line 14 through the ACZDC converter 58 is assisted. In this state, the power of the battery 5 4 is supplied to the DC power line 14. As a result, the voltage V of the DC power line 14 is controlled to coincide with the second command value A2. Therefore, the above shortage can be compensated without affecting the power generation of the solar cell 3 and the fuel cell 16 according to the power generation rules.

Further, the battery-side converter 57 activated 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. The battery-side converter 57 may be stopped again when the voltage V becomes the second threshold V 2 or higher.

Further, as shown in FIG. 2, for example, the DC distribution board 8 includes a DC breaker 70 and a pair of DCZDC converters 71. The DC breaker 70 is provided on the DC power line 14 and shuts 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 7 1 steps down the power of the DC power line 14 to an appropriate voltage and supplies it to the DC device 5. Where the DC breaker Since 70 does not step down the voltage of the DC power line 14, high voltage power can be supplied 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 in 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 supply power and demand power.

Control is performed to match the voltage V with the first command value A 1 (S 1 01). This 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 greater than or equal to the first threshold value V 1 (S 10 02). If it is determined that the voltage V is less than the first threshold V 1 (1 \ 10 in 51 02), power generation according to the power generation rules of the solar cell 3 and the fuel cell 1 6 through both converters 55 and 56 Is performed (S 1 03). Here, the power generation rule of the solar cell 3 is executed through MP P T control. Then, the process proceeds to step S 1 05. On the other hand, when it is determined that the voltage V is greater than or equal to the first threshold value V 1 (YES in 102), the output power P out is suppressed through both converters 55 and 56 (S 104). Thereafter, the process proceeds to step S 1 05.

In step S 105, it is determined whether or not voltage V is equal to or lower than second threshold value V 2. If it is determined that the voltage V is less than or equal to the second threshold value V2 (YES in S1 05) and the voltage V is less than the second command value A2, the voltage V Is controlled to the second command value A 2 (S 1 06). This completes the processing of the power supply program. On the other hand, if the voltage V exceeds the second threshold value V 2 (NO in S 1 05), in step S 1 07, the battery-side converter 57 remains stopped and the processing of the power supply program is terminated. The

In this flowchart, step S 1101 is executed through bidirectional converter 60, and steps S 1 03 to S 104 are executed through first and second converters 55 and 56, and steps S 1 06 to S 1 07 are executed. Is executed through the battery side converter 57.

Next, the reverse power flow restriction processing procedure executed by the control unit 51 will be described with reference to the flowchart of FIG. 5 (b). This 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 (S 1 51). Next, it is determined whether or not the calculated power amount Wh is greater than or equal to a threshold value Wh 1 (S 1 52).

When the electric energy Wh is less than the threshold value Wh 1 (1 \! 0 in S 1 52), the processing of the reverse flow regulation program is terminated. It is monitored whether the electric energy Wh reaches the threshold value Wh 1 by repeating the program every predetermined control cycle.

When the electric energy Wh exceeds the threshold value Wh 1 (YES in S 1 52), in other words, reverse When the tide reaches the maximum allowable electric energy, the battery 54 is charged with the electric power of the DC power line 14 through the battery-side converter 57 (S 1 5.3). At this time, 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 comparator 5 7. As a result, the reverse power flow after the reverse power reaches the maximum allowable energy can be prohibited.

When reverse power flow is prohibited, it can be assumed that the threshold value W h 1 is set to zero, and is always YES in step S 1 5 2. Processing is executed.

As mentioned above, according to embodiment described, there can exist the following effects.

(1) By matching the voltage V of the DC power line 14 with the first command value A 1 through the bidirectional converter 60 so that the voltage V of the DC power line 14 matches the first command value A 1, Supply power and demand power can be balanced. Therefore, it is not necessary to adjust the generated power of the solar cell 3 and the fuel cell 16 even if an imbalance between the generated power and the demand power occurs. As a result, regardless of the power demand of the DC device 5, the solar cell 3 and the fuel cell 16 can generate power with their own power.

(2) When the voltage V of the DC power line 14 is 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 the both comparators 5 5 and 5 6, and suppresses the increase in the voltage V of the DC power line 14. As a result, the occurrence of overpower in the power distribution system 1 is suppressed, and the safety of the system 1 can be improved.

(3) The voltage V is controlled to match the second command value A2. Specifically, when the voltage V of the DC power line 14 is less than the second command value A 2, the control is executed by discharging the power of the battery 5 4 to the direct power line 14. . Here, the second command value A 2 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 power line 14 is less than the second command value A2, it is conceivable that power cannot be supplied from the AC power line 23 to the DC power line 14 due to, for example, a power failure. Even in this case, the electric 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. As a result, 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 rules.

(4) When the voltage V of the DC power line 14 falls below the second threshold V 2, the battery-side converter 5 7 is activated. In this way, the battery-side converter 57 can be stopped until the voltage V of the DC power line 14 becomes equal to or lower than the second threshold value V 2, so that standby power until startup can be eliminated. In addition, by starting the battery side converter 5 7 before it becomes less than the second command value A 2, when the battery command converter 5 7 becomes less than the second command value A 2, the battery side converter 5 7 Can be discharged to the DC power line 14. to this This makes it possible to compensate for the shortage of power supply 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 power generated by 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 flowing backward to the AC power source 2. As a result, reverse power flow can be prohibited without adjusting the power generated by the solar cell 3 and the fuel cell 16.

(7) The voltage V of the DC power line 14 detected through the AC / DC converter 58 can determine whether the supplied power and the demand power are in an equilibrium state. Furthermore, by controlling the voltage V of the DC power line 14 through the bidirectional converter 60 so as to coincide with the first command value A 1, the supplied power and the demand power can be balanced. In this way, the control unit 51 can easily balance the supplied power and the demand power through the bidirectional converter 60. Here, for example, a configuration is considered in which the power used by the load device and the power generated by the power generation device are received, and based on them, the control unit performs control through the bidirectional converter 60 according to a predetermined algorithm stored in itself. It is done. However, compared with this configuration, in this embodiment, communication with a load device or a power generation device is not necessary. Also, since the feed pack control is performed only by looking at the voltage V of the DC power line 14, complicated control related to such communication can be omitted. As a result, for example, it is possible to cope with a sudden solar radiation fluctuation of the solar cell 3 and a sudden power imbalance due to a sudden load change due to the ON OF 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 among the converters 55 to 59 (more precisely, each CPU 65). Is different. In the following, the difference from the first embodiment will be mainly described.

Each converter 55 to 58 recognizes the voltage V of the DC power line 14 through its own output voltage detection circuit 62 (see FIG. 3). The DCZAC converter 59 recognizes the voltage V of the DC power line 14 through the input voltage detection circuit 61. In this case, the input side of the DC / AC converter 59 in FIG. The first converter 55 and the second converter 56 store the first threshold value V 1 in their own memory 65a. Then, both converters 55 and 56 suppress their outputs when voltage V reaches first threshold value V 1. Further, the ACZD C converter 58 and the DC / AC converter 59 constituting the bidirectional converter 60 store the first command value A 1 in its own memory 65 a. When the voltage V is less than the first command value A1, the output current iout is decreased through the DC / AC comparator 59 or the output current Iout is increased through the A CZDC converter 58. Further, when the voltage V exceeds the first command value A 1, the output current iout is increased through the DCZAC converter 59 or the output current Iout is decreased through the A CZDC converter 58. Thus, the voltage V is controlled so as to match the first command value A 1 as in the above embodiment.

Further, 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 comparator 57 is activated when the voltage V reaches the second threshold value V2, and when the voltage V becomes less than the second command value A2, the power of the battery 54 is supplied to the DC power line 14. Discharge and execute control to make the voltage V coincide with the second command value A2.

Further, the battery side converter 57 recognizes the threshold value Wh 1 included in the information about the reverse power obtained through the signal line 17. Further, the battery side converter 57 calculates the amount of electric power Wh based on the reversely flown power output from the reverse flow power detection circuit 50. As in the first embodiment, when the electric energy Wh reaches the threshold value Wh 1, the battery-side converter 57 charges the battery 54 by an amount corresponding to the reverse power. Ban reverse power flow.

As described above, according to the described embodiment, the following operational effects can be obtained in addition to the operational effects (1) to (7) of the first embodiment.

(8) The control unit 51 in the first embodiment can be omitted. As a result, the control unit 7 can have a simpler configuration, and costs associated with the control unit 51 can be reduced. In addition, each converter 55 to 58 generates power according to its own power generation rules 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 balance can be achieved. In addition, the communication of each converter 55-58 becomes unnecessary, and the processing related to it becomes unnecessary. As a result, the power balance state can be realized more quickly. Further, since each converter 55 to 58 is configured independently, the system can be easily updated and expanded. Specifically, the system can be updated by replacing each converter 55-58 as necessary.

Further, as in the first embodiment, the battery-side converter 57 can prohibit reverse power flow or limit the amount of power W h that is reverse flow.

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 each of the comparators 55 to 59 by the power supply program executed according to the flowchart of FIG. 5 (a). The control unit 51 may execute different programs through the converters 55 to 59. In this case, step S 1101, steps S1 02 to S 104, and S 105 to S 107 are independent program processing procedures. Specifically, the control unit 51 always performs the process of step S 1101 through the bidirectional converter 60. At the same time, the control unit 51 performs the processing of steps S 1 02 to S 1 0 4 through both converters 55 and 56 at predetermined intervals, and also steps S 1 05 to S 1 0 through the battery-side comparator 57. Process 7 is performed. In the second embodiment, the bidirectional converter 60, both converters 55, 56, and the battery side converter 57 are each executed by the above-described processing procedure.

In the above embodiment, the power that flows backward by charging the battery 54 is adjusted. You can adjust the reverse power flow through the discharge of the battery 54. 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 reverse flow.

In both the above embodiments, when prohibiting the reverse power flow, the power corresponding to the power detected through the reverse power detection circuit 50 is transferred from the DC power line 14 to the battery side comparator. The battery 5 4 was charged through 5 7. However, a part of the detected reverse power flow power may be charged to the battery 54 through the reverse power detection circuit 50. In this case, the reverse power flow can be adjusted arbitrarily.

-In the first embodiment, the control unit 51 calculates the power amount W h based on the detection result of the reverse power detection circuit 50. h may be calculated. In this case, the reverse power detection circuit 50 directly 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 W h in the same manner.

• In both the above embodiments, reverse power flow was recognized in a predetermined period. However, it may be a power distribution system 1 in which no reverse power flow is observed. 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 A CZ D C converter 5 8. However, the control unit 51 may recognize the voltage V through another converter, for example, the battery side converter 57. In addition, 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 DC power generators, but the DC power generator is not limited to this as long as it generates DC power. For example, a storage battery or a wind power generator may be used. For storage batteries and wind power generators, there are power generation rules that are suitable for them in terms of power generation efficiency and life. Further, the DC power generation device may be constituted by only the solar cell 3 or only the fuel cell 16.

'In the above embodiments, the first and second threshold values V 1 and V 2 and the first and second command values A 1 and A 2 are set. V 2 and second command value A 2 may be omitted. Even in this case, the supply voltage and the demand power can be balanced by controlling the voltage V to the first command value A1. For example, only the first threshold value V 1 or only the second threshold value V 2 can be omitted. Further, the second threshold value V 2 and the second command value A 2 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 AC system The power demand and supply power are balanced by transmitting and receiving the power through the bidirectional converter 60 through the power line 2 3 and the current system power line ¹⁴ .

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these specific embodiments, and various changes and modifications can be made without departing from the scope of the subsequent claims. Yes, it can be said to belong to the category of the present invention.

Claims

The scope of the claims

[Claim 1]

A direct current power system in which direct current power generated by the direct current power generator is supplied to a direct current load through a direct current wiring, and an alternating current in which alternating current power is supplied from the alternating current power supply through the alternating current wiring, in cooperation with the direct current power system. In a power distribution system comprising:

A bidirectional converter that converts AC power from the AC wiring into DC power, and DC power from the DC wiring into AC power;

By controlling the bidirectional converter so that the voltage of the DC wiring becomes a reference value, a control unit for balancing supply power to the DC wiring and demand power required through the DC wiring; Power distribution system provided.

[Claim 2]

DC power connected to the DC wiring and input from the DC power generator is converted into desired DC power according to a predetermined control rule stored in itself, and the converted DC power is supplied to the DC load. A DCDC converter to be supplied; and a voltage detection means for detecting a voltage of the DC wiring; and the control unit is configured so that the voltage of the DC wiring detected through the voltage detection means becomes a reference value. The power distribution system according to claim 1, wherein the power supply to the DC wiring and the demand power required through the DC wiring are balanced by controlling a direction converter.

[Claim 3]

The control unit suppresses the generated power of the direct current power generation device through the control of the DCDC converter when the voltage of the DC wiring detected through the voltage detection means becomes equal to or greater than an upper limit value greater than the reference value. The power distribution system according to claim 2, wherein the voltage of the DC wiring is controlled to be less than an upper limit value.

[Claim 4]

A battery connected to the DC wiring; and a charge / discharge circuit that is provided between the DC wiring and the battery, charges the battery with electric power of the DC wiring, and discharges the electric power of the battery to the DC wiring. The control unit should match the DC wiring with the lower limit value when the voltage of the direct current wiring detected through the voltage detection means becomes less than a lower limit value smaller than the reference value. 4. The power distribution system according to claim 2, wherein the charge / discharge circuit is controlled.

[Claim 5]

The control unit activates the charge / discharge circuit when a voltage of the DC wiring detected through the voltage detection unit becomes equal to or lower than a threshold value set to a value between the reference value and a lower limit value. Item 5. The power distribution system according to item 4.

[Claim 6]

A reverse power that is connected to the AC wiring and detects the power flowing backward to the AC power supply A power detection circuit; and Item 6. Distribution system according to item 4 or 5.

[Claim 7]

The control unit prevents the reverse power flow by charging the battery with the electric power of the DC wiring by the amount corresponding to the reverse power flowing detected by the reverse power detection circuit, through the charge / discharge circuit. 6. The power distribution system according to 6.

[Claim 8]

The control unit is provided in a distributed manner in the DC / DC converter, the bidirectional converter, and the charge / discharge circuit, the charge / discharge circuit stores the lower limit value, and the voltage of the DC wiring is When it becomes less than the lower limit value, the battery charge / discharge control is performed so as to match the lower limit value, and the DCZ DC converter stores the upper limit value and the voltage becomes equal to or higher than the upper limit value. The output voltage is controlled so that the voltage of the DC wiring is less than the upper limit value, and the bidirectional converter stores the reference value, and when the voltage deviates from the reference value, the DC wiring 8. The power distribution system according to any one of claims 4 to 7, wherein output power to the DC wiring and the AC wiring is controlled so that the voltage of the power supply matches the reference value.