WO2011058405A1 - Power distribution system - Google Patents

Abstract

Disclosed is a power distribution system equipped with a DC electric power system in which DC electric power is supplied to a DC load via a DC supply line. The power distribution system is equipped with: a battery which is connected to the DC supply line; a charge/discharge circuit which is provided between the DC supply line and the battery, and which charges the battery with electric power from the DC supply line and discharges the electric power from the battery to the DC supply line; and a control unit which controls the charge/discharge of the battery via the charge/discharge circuit so that the voltage of the DC supply line matches a reference value.

Description

 Description 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. Converts the DC power generated by the fuel cell 102 and the fuel cell 102 generated by the chemical reaction between the converter 103, which converts the output voltage Vo ut and supplies power to the load, and the chemical reaction of the substance into the appropriate output voltage V out. It consists of a converter 104 that supplies 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 solar cell 101 can be controlled by converter 103 so that it can operate at Vmp, the maximum output power Pmax can be output from solar cell 101, and solar cell 101 can be used efficiently. Will be. This control to output the output power from the solar cell 101 with Pma X and make the best use of the solar cell 101 is called maximum output operating point tracking control (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, the direct current power generators such as the solar battery 101 and the fuel battery 102 have an actual benefit of generating electric power in accordance with the respective circumstances such as the power generation rule and the MPPT 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 Patent Document 1 above, the power generated by the solar battery 101 and the fuel battery 102 and the power consumed by the DC load 105 are lost in various power conversion devices. If power loss and wiring loss are 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. . Conversely, in the case of power consumption exceeding the power generation capacity of the solar cell 10 1 or the fuel cell 10 2, for example, the fuel cell 1 0 2 may output power by violating the above 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.

 In this way, in DC power generators such as solar cell 101 and fuel cell 102, depending on the power consumption (demand power) of DC load 105, power generation according to MPPT control etc. may not be possible. is there. Summary of the Invention

 The present invention has been made in view of such circumstances, and provides a power distribution system that enables power generation suitable for itself in a DC power generation device regardless of the power demand of the DC load.

 According to an embodiment of the present invention, in a power distribution system including a direct current power system in which direct current power is supplied to a direct current load through a direct current wiring, the power distribution system includes a battery connected to the direct current wiring, and the direct current wiring. And a charging / discharging circuit for charging the battery with electric power of the DC wiring, and discharging the electric power from the battery to the DC wiring, and charging / discharging of the battery via the charging / discharging circuit. A control unit that performs control, and the control unit controls charging / discharging of the battery via the charging / discharging circuit so that a voltage of the DC wiring matches a reference value.

 In the power distribution system, the DC power is generated by a DC power generator, and the DC power provided on the DC wiring and input from the DC power generator according to a predetermined control rule stored in itself. A DCZDC converter that converts the DC power into desired DC power and supplies the DC load; and voltage detection means that detects a voltage of the DC wiring; and the control unit detects the DC wiring detected through the voltage detection means. By controlling charging / discharging of the battery through the charging / discharging circuit so that the voltage of the battery matches a reference value, the supply power to the wiring and the demand power required through the DC wiring are balanced. Also good.

 According to the above configuration, charging / discharging of the battery is controlled so that the voltage of the DC wiring matches the reference value. When the voltage of the DC wiring matches the reference value, the supply power and the demand power are in a balanced state, so the supply power and the demand power can be balanced by controlling the voltage of the DC wiring to the reference value. . Therefore, even if there is an imbalance between the power generated by the DC power generator and the demand power of the DC load, it is not necessary to adjust the power generated by the DC power generator. As a result, regardless of the power demand of the DC load, the DC power generator can generate power with its own appropriate power.

 The DC power generation device includes a solar cell that converts light energy from the sun into DC power, and the control rule that the DCC DC converter corresponding to the solar cell follows is the maximum output of the solar cell. It may be operating point tracking control.

Generally, there is a maximum output voltage value that outputs maximum power as an output characteristic of a solar cell. In other words, maximum output operating point tracking control that can generate power most efficiently by setting the output voltage of the solar cell to the maximum output voltage value is known. Here, in the above configuration, the output power of the solar cell is the input power of the DCZ DC converter. Therefore, by operating the DC / DC converter at the maximum output voltage point that maximizes the input power, the power can be obtained from the solar cell with high efficiency. In addition, as described above, the power supply and demand power are balanced by the battery. Therefore, since it is not necessary to suppress the power generation efficiency of the solar cell, the loss of generated power can be reduced.

 In addition, when the voltage of the DC wiring detected through the voltage detection unit becomes equal to or greater than an upper limit value greater than the reference value, the control unit generates power generated by the DC power generation device through the DC / DC converter. It may be controlled so that the voltage of the DC wiring is less than the upper limit value.

 The battery may be fully charged or the battery may be charged beyond its maximum charge / discharge current. In such a case, the voltage of the DC wiring rises. In 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 lower than the upper limit value. In other words, the generated power from the DC generator is suppressed by the control unit through the DCZDC converter. Therefore, the increase in the voltage of the DC wiring is suppressed, so that the safety of the power distribution system can be improved.

 The DC wiring is connected to an AC power system that is supplied with AC power from an AC power source through AC wiring, and is installed on a cross-flow connection line that connects the DC wiring and the AC wiring. An AC-side converter that converts AC power from the AC wiring into DC power based on a command from the control unit and outputs the DC power to the DC wiring, and the control unit detects the DC detected through the voltage detection unit When the voltage of the wiring becomes less than the lower limit value less than the reference value, the AC wiring power is output to the DC wiring through the AC converter, and the DC wiring is controlled to match the lower limit value. May be.

According to the above configuration, the voltage V is controlled to match the lower limit value. Specifically, this control is executed by supplying power to the DC wiring from the AC power system through the AC side comparator when the voltage of the DC wiring becomes less than the lower limit. Here, the lower limit value is desirably a value close to the reference value from the viewpoint of quickly setting the voltage of the DC wiring as the reference value. However, if both the command values are set too close, the following adverse effects are assumed. For example, when the voltage of the DC wiring becomes less than the reference value, it takes a certain time from the detection of the voltage of the DC wiring to the start of battery discharge until the voltage is actually controlled to the reference value. Thus, if the voltage is below the lower limit due to a decrease in the voltage of the DC wiring based on the reference value based on the delay in voltage control of the DC wiring, the voltage is reduced by discharging the battery. Despite being able to maintain the reference value, power will be supplied from the AC power system to the DC wiring. Therefore, the lower limit value is close to the reference value, and is set to be less than the minimum voltage value that can be detected based on the voltage control delay of the DC wiring as described above. Therefore, the voltage drops below the lower limit at a more appropriate timing, and the voltage drop in the DC wiring is quickly eliminated. As a result, the balance between supply power and demand power can be realized quickly. The control unit is provided in a distributed manner in the DC / DC converter, the AC converter, and the charge / discharge circuit, the charge / discharge circuit stores the reference value, and the voltage of the DC wiring is The battery charge / discharge control is performed so as to match a reference value, the DC / DC converter stores the upper limit value, and performs control so that the voltage of the DC wiring is less than the upper limit value, The AC-side converter may store the lower limit value and control output power to the DC wiring so that the voltage of the DC wiring matches the lower limit value.

 According to the above configuration, the control unit force is distributed among the converters. Therefore, each converter independently controls the DC wiring voltage through comparison of the DC wiring voltage and the reference value, upper limit value, or lower limit value stored in each converter. In this way, each converter can balance supply power and demand power without communicating with other converters.

 In addition, the control unit, when the voltage of the DC wiring detected through the voltage detection unit becomes equal to or less than a threshold value set to a value between the reference value and the lower limit value, the AC side converter. May be activated.

 According to the said structure, when the voltage of DC wiring becomes below a threshold value, an AC side converter is started. In this way, the AC-side converter can be stopped until the voltage of the E-flow wiring falls below the threshold value, so the standby power of the AC-side converter until startup can be eliminated. In addition, by starting the AC side converter before it becomes less than the lower limit value, when the AC side converter becomes less than the lower limit value, the AC side converter immediately converts AC power from the AC power system into DC power, and this Can be supplied to the DC wiring. As a result, a shortage of power supplied to the DC load can be compensated more quickly. As described above, in the AC-side converter, it is possible to achieve both tracking controllability with respect to voltage drop and reduction in power consumption. 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

 Objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:

 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 8 in the first embodiment. FIG. 4 is a graph showing transitions of the first and second threshold values, the first and second command values, and the voltage V in the first embodiment, and (b) is the first command value and The graph which shows transition of voltage V.

 FIG. 5 is a flowchart showing a processing procedure of a power supply program in the first embodiment. 6 is an enlarged block diagram of a part of FIG. 1 according to 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 the 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. Parts that are the same or similar throughout the drawings are given the same number, and redundant explanations thereof are 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 to the 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 8 (with built-in DC breaker). Further, the power distribution system 1 is provided with a control unit 9 and a release 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. The AC power distribution panel 11 is connected to an AC power source 2 and an AC device 6 through an AC power line 23. A solar battery 3 is connected to the control unit via a DC power line 13, and a fuel cell 16 is connected to the control unit via a DC power line 15. The control unit 7 takes in AC power from the AC distribution board 11 and also takes in DC power from the solar cell 3 and the fuel cell 16 and converts them 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 not only captures AC power, but also converts solar cell 3 and fuel cell 16 power into AC power and supplies it to the AC distribution board 11. In addition, the control unit executes data collection with the DC distribution board 8 via the signal line 17.

 The DC distribution board 8 is a type of breaker that supports DC power. The DC distribution board 8 branches the DC power input from the control unit unit and outputs the DC power after the branch to the control unit 9 via the DC power line 18 or the DC power line 19 Or output to relay unit 10 via In addition, the DC distribution board 8 performs data recovery with the control unit 9 via the signal line 44, and reroute 10 via the signal line 45. Data is collected and collected.

A plurality of DC devices 5 are connected to the control unit 9. These DC devices 5 are connected to a 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 2 2 has a high DC voltage that is a power source for DC equipment. A pair of wires carries both power and data to the DC equipment 5 by so-called power line carrier communication, which superimposes a communication signal for transmitting re-data by a frequency carrier wave. The control unit 9 acquires the DC power source of the DC device 5 through the DC power line 1 8 and selects which DC device 5 based on the operation command obtained from the DC distribution board 8 through the signal line 44. Figure out how 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 and controls 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. Further, for example, a sensor 24 that detects a radio wave transmitted from an infrared 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, the 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 based on the operation command obtained from the DC distribution board 8 through the signal line 45. Figure out what will work. Then, the relay unit 10 controls the operation of the DC device 5 by turning on and off the power supply to the DC power line 25 with a built-in relay with respect to the instructed DC device 5. The relay unit 10 is connected to a plurality of switches 46 for manual operation of the DC device 5. The operation of the switch 46 turns on / off the power supply to the DC power line 25. By doing so, the DC device 5 is controlled.

 The DC distribution board 8 is connected to a DC outlet 27, which is 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 DC device plug (not shown) is inserted into the DC outlet 27, DC power can be directly supplied to the device.

 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. In the network system 30, a home server 31 is provided as a control unit for the system 30. The in-home server 3 1 is connected to the management server 3 2 outside the home via a network N such as the Internet, and is connected to the in-home equipment 3 4 through a signal line 3 3. The in-home server 3 1 operates using DC power acquired from the DC distribution board 8 through the DC wiring 35 as a power source.

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 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. Conto 1 Lupok For example, a gas / water meter 39 capable of remotely metering the amount of gas used and the amount of water used, and an operation panel 40 of the network system 30 are connected to the network 36. 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 31 inputs operation commands for various devices in the home via the network N, the home server 31 notifies the control box 36 of the instructions, and operates the control box 36 so that the various devices operate in accordance with the operation commands. . In addition, the in-home server 31 can provide various information acquired from the gas / water meter 39 via the control unit 36 to the management server 32 via the network N, and the monitoring device 41 can detect an abnormality. If it is received from the operation panel 40, that fact is also provided to the management server 32 via the network N.

 Next, a specific configuration of the control unit will be described.

 As shown in FIG. 2, the control unit includes a control unit 51, a first DC / DC converter (hereinafter referred to as “first converter”) 55, a second DCZDC converter (hereinafter referred to as “first DC / DC converter”).

This is called “second converter”. ) 56, battery side converter 57, AC / DC converter 58, and battery 54.

 The first converter 55 converts the DC power input from the solar cell 3 (solar cell power P p v) 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 circuit that detects the voltage value on the DC distribution board 8 side. 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 65 a.

 The CPU 65 appropriately controls the power circuit 64 in accordance with a program stored in the memory 65a. Specifically, the MP PT 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 MP PT 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 MP PT control, as described with reference to FIG. 7 in the above background technology, the CPU 65 converts the output power P out (solar cell power P pv) through the power circuit 64 to the maximum output power P m a Control to X.

 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. Convert to DC distribution board 8 and output. The specific configuration of the second converter 56 is almost the same as that of the first comparator 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 regulate 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 comparator 5 7 and the battery 5 4 are connected to the DC power line 14 via the battery connection line 53. The battery-side converter 5F converts the power of the DC system power line 14 to the desired power and charges the battery 54, or converts the power charged in the battery 54 to the desired power and converts it to the DC system power line. 1 Discharge to 4. Specifically, the battery-side comparator 5 7 performs charge / discharge control of the battery 5 4 through control of the output current I output output to the DC power line 14. The battery side converter 57 is a D CZ D C bidirectional converter. The specific configuration of the battery-side converter 5 7 is almost the same as that of the first comparator 5 5 shown in Fig. 3 except that it can output power in both directions on the battery 5 4 side and the DC power line 1 4 side. It is the same. The battery-side converter 5 is controlled by the control unit 51 and outputs the detection result of the output voltage detection circuit 62 to the control unit 51. Based on the detection result, the control unit 51 can recognize the voltage V of the battery connection line 53 and eventually the DC power line 14.

 A CZ D C converter 58 converts the AC power from AC power line 23 into desired DC power. In this way, by providing the AC / DC converter 58 in the cross flow connecting line 12, AC power can be converted into DC power and transmitted to the DC power line 14.

 The control unit 51 outputs a command signal to the battery-side converter 57 based on the power supply program stored in the memory 51a. Further, the control unit 51 constantly monitors the voltage V of the DC power line 14 through the battery side converter 57. Specifically, as shown in FIG. 4 (a), the control unit 51 controls the voltage V and the first and second threshold values V 1, V 2 and the first threshold stored in its own memory 51 a. And the second command values A 1 and A 2 are compared.

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 generated 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. When the voltage V exceeds the first command value A1, the control unit 51 determines that the supplied power is greater than the demand power.If the voltage V is less than the first command value A1, the power supply is less than the demand power. Judge that it is small. Then, as shown in FIG. 4 (b), the control unit 51 controls the battery side converter 5 through the battery side converter 5 7 during the periods T 1 and T 2 when the voltage V exceeds the first command value A 1. Reduce the output current I out of 7. Here, as shown in the lower part of Fig. 4 (b), when the output current Iout is positive, the power of the battery 54 is discharged, and when the output current Iout is negative, the DC power line 1 4 power is charged to battery 54. Specifically, output current lout in period T1 Since the value gradually decreases with a positive value, the electric power discharged from the battery 54 is suppressed. Next, since the value of the output current I out changes from positive to negative in the period T 2, switching from discharging to charging is performed. In the period T 3 when the voltage V is less than the first command value A 1, the output current lout of the battery-side converter 5 7 is increased through the battery-side converter 5 7. During this period T3, the value of the output current Iout changes from negative to positive, so that the charging is switched to discharging. With this control, the voltage V is controlled to coincide with the first command value A1.

 At the time of charging, “the surplus power calculated by the generated power—the consumed power J is charged to the battery 54, whereby the voltage V is suppressed and the power balance state is reached. In addition, at the time of discharging, the battery 54 is discharged to make up for the insufficient power calculated by “demand power minus generated power”.

 By the above control, the voltage V is controlled so as to coincide with the first command value A1, and the supplied power is controlled so as to be different from the demand power in an equilibrium state. As a result, the solar cell 3 and the fuel cell 16 can generate power suitable for their own situation regardless of the demand 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 power generation executed through MPPT control. Power generation rules are equivalent to control rules.

 The first threshold value (upper limit value) V I is set to a value larger than the first command value A 1 as shown in Fig. 4 (a). When the generated power is larger than the demand power, the voltage V becomes equal to or higher than the first threshold value V 1 when the surplus power cannot be sufficiently charged in the battery 54. As a case where the battery 5 4 cannot be fully charged, it is assumed that the battery 5 4 is fully charged or is charged beyond the maximum charging current of the battery 54. For example, when the battery 54 is fully charged, the surplus power cannot be charged in the battery 54, so that the voltage V of the DC power line 14 increases. In addition, when charging with a current exceeding the maximum charging current, the chargeable power of the battery 54 is less than the surplus power, and the voltage V of the DC power line 14 may not be suppressed quickly. is there.

 As shown in Fig. 4 (a), the control unit 51 increases the voltage V of the DC power line 14 and reaches the first threshold value V1 (time t1 in Fig. 4 (a)). The output power Pout is suppressed 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 controlling the output power of the second converter 56, 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 (lower limit) A 2 is smaller than the “I command value A 1”, and the second threshold V 2 is set to a value between the first command value A 1 and the second command value A 2. The second command value A 2 is preferably set to a value close to the first command value from the viewpoint of quickly setting the voltage V to the first command value A 1. If the command values A "I and A2 are set too close to each other, there are the following problems. For example, when the voltage V becomes less than the first command value A1, the charge / discharge control of the battery 54 starts from the detection of the voltage V through the battery side converter 57, and the voltage V is actually set to the first command value. It takes a certain time until it is controlled to the value A1. Thus, the voltage control of the DC power line 14 If the voltage V is less than the second command value A 2 due to a decrease in the voltage V from the first command value A 1 based on the delay of the Although it can be maintained at 1, the power is supplied from the AC power line 23 to the DC power line 14. As a result, even if the voltage V is slightly changed, control through the ACZDC converter 58 is performed, which leads to an increase in the operating power of the ACZDC converter 58. Therefore, the second command value A 2 takes a value close to the first command value A 1 and is set to be less than the minimum voltage value that can be detected based on the voltage control delay of the DC power line 14. ing.

 The control unit 51 performs control to make the voltage V of the DC power line Ί4 coincide with the second command value A2. In this control, when the voltage V decreases and reaches the second command value A 2 (time t 3 in FIG. 4 (a)) and further becomes less than the second command value A 2, the AC ZDC converter 58 passes the AC This is performed by converting AC power from the system power line 23 to DC power and supplying it to the DC system power line 14. Here, ACZDC converter 58 is stopped until voltage V reaches second threshold value V 2 which is larger than second command value A 2.

 Further, the control unit 51 activates the A CZDC converter 58 when the voltage V decreases and reaches the second threshold value (threshold value) V2. Here, the ACZDC converter 58 is stopped until the voltage V reaches the second threshold value V2. In addition, ACZDC converter 58 requires a certain period of time from the start of startup until 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, the second threshold value V 2 is set so that the start-up of A CZDC converter 58 is completed when the voltage V reaches the second command value A 2. Has been. Therefore, when the voltage V reaches the second command value A 2 by starting the A CZD C converter 58 when the voltage V reaches the second threshold value V 2 (FIG. 4 ( At time t 3) of a), power can be supplied to the DC power line 14 through the A CZDC converter 58. As a result, the above shortage can be compensated more quickly. Further, since ACZDC converter 58 is stopped until voltage V reaches second threshold value V 2, it is possible to reduce power consumption related to the operation of AC DC converter 58. Therefore, when the voltage V of the DC system power line 14 is less than the second command value A2, the power from the AC system power line 23 is supplied to the DC system power line 14 in a form that assists the discharge of the battery 54. . As a result, the voltage V of the DC power line 14 is controlled to the second command value A2. Therefore, the insufficient power can be maintained without affecting the power generation of the solar cell 3 and the fuel cell 16.

 Further, the AC DC converter 58 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. The ACZDC converter 58 may be stopped again when the voltage V exceeds the second threshold value V2.

Further, as shown in FIG. 2, the DC distribution board 8 includes, for example, 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 abnormal current from flowing into the DC device 5. The DCZDC converter 71 steps down the DC power of the DC power line 14 to an appropriate voltage and supplies it to the DC device 5. Where the DC breaker Since the force 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 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 power supply and power demand.

Control is executed so that the voltage V matches the first command value A 1 (S 1 01). This control is performed through the control of the output current _OU t of the battery side converter 57 as described above. Then, it is determined whether or not the voltage V is equal to or higher than the first threshold value V 1 (S 1 02). When it is determined that the voltage V is less than the first threshold value V 1 (NO in S 102), power is generated according to its own power generation rule through both converters 55 and 56 (S 103). Here, the power generation rule of the solar cell 3 is executed through MP PT control. On the other hand, when it is determined that the voltage V is equal to or higher than the first threshold value V 1 (YES in 102), the output power output is suppressed through both converters 55 and 56 (S 104).

 Next, it is determined whether or not the voltage V is equal to or lower than the second threshold value V 2 (S 1 05). When 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 reduced through the ACZDC converter 58. It is controlled to the second command value A2 (S1 06). This completes the processing of the power supply program. On the other hand, when voltage V exceeds second threshold value V2 (NO in S106), ACZDC converter 58 is maintained in the stopped state, and the power supply program process is terminated.

 In this flowchart, step S 1101 is executed through the battery-side converter 5, and steps S “I 03 to S 104 are executed through the first and second converters 55, 56. Steps S 1 06 to S 1 07 are executed through the ACZDC converter 58.

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

 (1) Charging / discharging of the battery 54 is controlled so that the voltage of the DC power line 14 matches the first command value A1. When the voltage V of the DC power line 14 coincides with the first command value A1, the supply power and the demand power are in equilibrium. Therefore, by controlling the voltage V of the DC power line 14 to the first command value A 1, the supply power and the 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 when there is an imbalance between the generated power and the demand power. 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) Through the first converter 55, the output power Pout is controlled so that the input voltage (solar battery power P pv) becomes the maximum output voltage Vmp, so that power can be obtained from the solar battery 3 with high efficiency. Can do. As described above, the supply power and the demand power are balanced by charging and discharging the battery 54. Therefore, since it is not necessary to suppress the power generation efficiency of the solar cell 3, the loss of generated power can be reduced. (3) The battery 5 4 may be fully charged or the battery 5 4 may be charged beyond its maximum charge / discharge current. In such a case, the voltage of the DC power line 14 increases. In the present invention, 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 generated power is suppressed by the control unit 51 through the both converters 5 5 and 5 6. Therefore, since the increase in voltage of the DC power line 14 is suppressed, for example, overpower that may affect the operation and distribution of the DC apparatus 5 is supplied to the DC device 5 and the DC power line 14. Can be prevented. Therefore, the safety of the power distribution system 1 can be improved.

 (4) The voltage V is controlled to match the second command value A2. Specifically, in this control, when the voltage V of the DC power line 14 becomes less than the second command value A 2, power is supplied from the AC power system to the DC power line 14 through the A CZ DC converter 58. It is executed by being executed. Here, the second command value A 2 is preferably a value close to the first command value A 1 from the viewpoint of quickly setting the voltage V of the DC power line 14 to the first command value A 1. However, if both the command values A 1 and A 2 are set too close, the following adverse effects are assumed. For example, if the voltage V of the DC power line 14 is less than the first command value A 1, the battery starts discharging from the detection of the voltage of the DC power line 14 and the voltage is actually set to the first command value. A certain time is required until the value A 1 is controlled. As described above, the voltage becomes less than the second command value A 2 due to the voltage drop of the DC power line 14 based on the first command value A 1 based on the delay of the voltage control of the DC system power line 14. Therefore, although the voltage V can be maintained at the first command value A 1 by discharging the battery 54, power is supplied to the DC power line 14 from the AC power system. Therefore, the second command value A 2 is close to the first command value A 1 and is less than the minimum voltage value that is expected to be detected based on the voltage control delay of the DC power line 14 as described above. Is set. Therefore, at an appropriate timing, the voltage V becomes less than the second command value A2, and the voltage drop on the DC power line 14 can be quickly eliminated. Therefore, the balance between supply power and demand power can be realized quickly.

 (5) When the voltage V of the DC power line 14 falls below the second threshold value V2, the A C Z D C converter 5 8 is activated. As described above, the AC Z D C converter 58 can be stopped until the voltage of the DC power line 14 becomes equal to or lower than the second threshold value, which leads to a reduction in the operating power of the A CZ D C converter 58. Also, by starting the A CZ DC converter 58 before it becomes less than the second command value A2, when the second command value A2 becomes less than the second command value A2, the ACZDC converter 58 immediately AC power can be converted to DC power and supplied to DC power lines 14. As a result, the shortage of power supplied to the DC device 5 can be compensated more quickly.

(6) 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, the supply power and the demand power can be balanced by controlling the charge / discharge of the battery 54 so that the voltage V of the DC power line 14 matches the first command value A 1. In this way, the control unit 51 can easily balance the supply power and the demand power through charge / discharge control of the battery 54. be able to. 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 these, the control unit performs charge / discharge control of the battery power 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. In addition, since the feedback 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 or a sudden power imbalance due to a sudden load change due to ONZOFF of the DC device 5.

 (Second embodiment)

 Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In the power distribution system of this embodiment, the control unit 51 is omitted, and the function is distributed to each of the converters 55 to 58 (more precisely, each of the CPUs 6 5). Different from the first embodiment. In the following, the difference from the first embodiment will be mainly described.

 Each converter 5 5 to 5 8 recognizes the voltage V of the DC power line 14 through its output voltage detection circuit 6 2 (see FIG. 3). The first converter 55 and the second converter 56 store the first threshold value V1 in their own memory 65a. Then, both converters 5 5 and 5 6 suppress their outputs when voltage V reaches first threshold value V 1. Further, the battery side converter 57 stores the first command value A "I in its own memory 65a, and the battery side converter 57 has a voltage V of the first value as in the above embodiment. 1 Control is performed so as to match the command value A 1. Further, the A CZ DC converter 58 stores the second threshold value V2 and the second command value A2 in its own memory 65a. The ACZDC converter 58 starts when the voltage V reaches the second threshold value V2, and converts the AC power of the AC power line 23 to DC power when the voltage V becomes less than the second command value A2. Then, output to the DC power line 14 side, and execute control to make the voltage V coincide with the second command value A2.

 As described above, according to the described embodiment, in addition to the effects (1) to (6) of the first embodiment, the following effects can be obtained.

 (7) The control unit 51 in the first embodiment can be omitted. Therefore, the control unit 7 can be configured in a simpler manner, and the cost associated with the control unit 51 can be suppressed. Each converter 5 5 to 5 8 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, the supplied power In addition, the power demand can be balanced. In addition, the communication of each of converters 5 5 to 5 8 becomes unnecessary, and the processing related to it becomes unnecessary. As a result, the power balance state can be realized more quickly.

 Furthermore, since each converter 5 5 to 5 8 is configured independently, it is possible to easily update and expand the system. Specifically, the system can be updated through the exchange of converters 5 5 to 5 8 as necessary.

In addition, the said embodiment can be implemented with the following forms which changed this suitably. • In both of the above embodiments, when the voltage V exceeds the first command value A 1, the battery 5 4 is charged with power, and when the voltage V becomes less than the first command value A 1, the battery 5 4 Discharge the power The The first command value A 1 may be set with a certain width value with the first command value A 1 as a central value so as to allow a minute voltage fluctuation due to noise or the like. In this case, frequent charging / discharging by the battery 54 is suppressed, and the life of the battery 54 can be extended.

 'In the first embodiment, the voltage V is recognized by the control unit 51 through the recharger side comparator 5 7. However, the control unit 51 may recognize the voltage V through the output voltage detection circuit 62 in the other converter, for example, the A CZ D C converter 58. Further, a voltage detection circuit may be provided separately from the converter.

 'In both the above embodiments, the power from the AC power line 23 could be supplied to the DC system side through the A CZ D C converter 58. The power distribution system 1 may be configured by omitting the AC system composed of the AC power line 2 3, the AC device 6 and the AC power source 2.

 -In both of the above embodiments, the fuel cell 16 and the solar cell 3 are provided as the DC power generator, but the DC power generator 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. 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 'the fuel cell 16 alone.

 In both 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 power and the demand power are balanced by controlling the voltage V to be the first command value A "1. According to this setting, the charging / discharging of the battery 54 is performed. In order to balance the supply power and demand power, it is recommended to use a battery with a maximum capacity of 5 4 or provide multiple batteries 5 4. For example, the first threshold V It is possible to omit only the first or second threshold value V2.

 The preferred embodiments of the present invention have been described above. However, 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 following claims. Can be said to belong to the scope of the present invention.

Claims

The scope of the claims [Claim 1]  In a distribution system comprising a DC power system in which DC power is supplied to a DC load via DC wiring,  A battery connected to the DC wiring;  Provided between the DC wiring and the battery, and charging the battery with electric power of the DC wiring;  A charge / discharge circuit for discharging electric power from the battery to the DC wiring;  A control unit that performs charge / discharge control of the battery through the charge / discharge circuit, and the control unit charges / discharges the battery through the charge / discharge circuit so that a voltage of the DC wiring matches a reference value. Power distribution system to control.  [Claim 2]  In the power distribution system,  The direct current power is generated by a direct current power generator, and the direct current power provided on the direct current wiring and input from the direct current power generator is a predetermined control rule stored in itself (thus, to a desired direct current power). A DCDC converter for converting and supplying the DC load;  Voltage detection means for detecting the voltage of the DC wiring,  The control unit controls the charging / discharging of the battery through the charging / discharging circuit so that the voltage of the DC wiring detected through the voltage detecting unit matches a reference value, thereby supplying the direct current wiring to the direct current wiring. The power distribution system according to claim 1, wherein electric power is balanced with demand power required through the DC wiring.  [Claim 3]  The DC power generator includes a solar cell that converts light energy from the sun into DC power, and the control rule that the DCC DC converter corresponding to the solar cell follows is the maximum output operating point tracking of the solar cell. The power distribution system according to claim 2, wherein the power distribution system is control.  [Claim 4]  The control unit suppresses the generated power of the DC power generation device through the DDC converter when the voltage of the DC wiring detected through the voltage detection unit is equal to or greater than an upper limit value greater than the reference value, and 4. The power distribution system according to claim 2, wherein the voltage of the wiring is controlled to be less than the upper limit value.  [Claim 5] The DC wiring is connected to an AC power system to which AC power is supplied from an AC power source through AC wiring, and is provided on a cross-flow connection line that connects the DC wiring and the AC wiring, and the control unit An AC-side converter that converts AC power from the AC wiring into DC power based on a command from the AC wiring and outputs the DC power to the DC wiring, and the control unit detects the DC wiring detected through the voltage detection means. When the voltage is less than the lower limit than the reference value, the AC side The power distribution system according to any one of claims 2 to 4, wherein power of the AC wiring is output to the DC wiring through a converter, and the DC wiring is controlled to match the lower limit value. [Claim 6]  The control unit is provided in a distributed manner in the DCZ DC converter, the AC side converter and the charge / discharge circuit, the charge / discharge circuit stores the reference value, and the voltage of the DC wiring is The charging / discharging control of the battery is performed so as to match a reference value, the DC / DC converter stores the upper limit value, and performs control so that the voltage of the DC wiring is less than the upper limit value, 6. The power distribution system according to claim 5, wherein the AC converter stores the lower limit value and controls output power to the DC wiring so that the voltage of the DC wiring matches the lower limit value.  [Claim 7]  The control unit activates the AC-side converter 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. Power distribution system.