JP2011078237A - Power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress electric power which is made to flow in reverse, while maintaining power generation efficiency of a power generation means utilizing natural energy in a power supply system. <P>SOLUTION: When the suppression of electric power made to flow in reverse is decided as being necessary, the output electric power of a fuel cell 4 is suppressed, preferentially, through control of a second converter 56. Thus, electric power supplied from the fuel cell 4 is suppressed, and the consumption of a fuel can be suppressed. As a result, the electric power made to flow in reverse can be suppressed, while maintaining power generation efficiency, as is, without suppressing the electric power generated from a solar cell battery 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In recent years, in addition to commercial power supplied from electric power companies, power supply systems that use generated power of solar cells using sunlight, which is a kind of renewable energy, as an energy source are becoming common. Conventionally, as a power supply system, for example, a configuration disclosed in Patent Document 1 has been adopted. That is, as shown in FIG. 5, the system includes a solar cell 101 that converts light energy from the sun into electric energy (DC power), and an inverter 103 that converts DC power generated by the solar cell 101 into AC power. And a commercial power supply 108 that supplies AC power to the load 105 in connection with the inverter 103.

  The commercial power supply 108 and the inverter 103 are connected via the first power line 111. The load 105 is connected to the first power line 111 through the second power line 112. A connection point between the power lines 111 and 112 is a power reception point 113 that receives power from the solar battery 101 and the commercial power source 108. Further, a pole transformer 115 that boosts the voltage from the commercial power supply 108 is provided on the first power line 111 closer to the commercial power supply 108 than the power reception point 113.

JP 2000-284838 A

  Electric power supplied from the commercial power source 108 is transmitted from substations installed in various places via the first power line 111 to the pole transformer 115 installed on the telephone pole, and further from the pole transformer 115 to the power line 112 and the like. Is transmitted to the load 105 of each home or the like. Here, since all the power lines have impedance, it is inevitable that a voltage drop occurs during power transmission. Therefore, the voltage Vr at the power receiving point 113 is lower than the system voltage Vs of the commercial power supply 108. For this reason, the system voltage Vs of the commercial power supply 108 is set slightly higher in anticipation of the voltage drop due to the impedance of the first power line 111. In the 100V system used in general households, the allowable voltage fluctuation is set to 101 ± 6V by the Electricity Business Law. Therefore, for example, the low-voltage side output of the pole transformer 115 is set to 105V. Thereby, at the time of no load, the voltage Vr of the power receiving point 113 becomes 105 V which is within the allowable voltage range. When the load is used, for example, even when a voltage drop of 4 V occurs, a voltage of about 101 V can be supplied to the load 105.

  On the other hand, the generated power from the solar cell 101 is allowed to flow backward to the commercial power source 108 through the first power line 111, so that the generated power can be sold to an electric power company that supplies the commercial power source 108. However, when the generated power from the solar battery 101 is reversely flowed, the voltage Vr at the power receiving point 113 may increase due to the influence of the impedance of the power lines 111 and 112. For example, assume that when the load 105 receives power from the commercial power supply 108 and consumes 30 A, a voltage drop of 4V occurs and the voltage Vr at the power receiving point 113 becomes 101V. In this case, in order to reversely flow 30A from the solar battery 101 side to the commercial power source 108, it is necessary to compensate for the voltage drop and set the voltage Vr at the power receiving point 113 to 109V. Thus, the voltage at the power receiving point 113 increases as the current to be reversely flowed increases due to the influence of the impedance of the power lines 111 and 112. Thus, when the voltage Vr at the power receiving point 113 is increased, an overvoltage exceeding 107 V, which is the maximum value of the allowable voltage, may be applied to the load 105, and the overvoltage is not preferable for the operation of the load 105.

  In order to suppress such a voltage increase at the power receiving point 113 during reverse power flow, for example, control for reducing the output current of the inverter 103 is performed. However, in this case, the power from the solar cell 101 is also suppressed, causing a loss of generated power. Thereby, although the solar cell 101 received sufficient solar radiation, the problem that the electric power corresponding to it cannot be sold has arisen. Such a problem occurs not only in the solar battery 101 but also in a power supply system in which the commercial power supply 108 is linked to a wind power generator using natural energy.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a power supply system that suppresses the power to be reversely flowed while maintaining the power generation efficiency of the power generation means using natural energy. .

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
According to the first aspect of the present invention, AC power is supplied to the AC load from the first power generation unit that generates power using natural energy and an AC supply source through an AC wiring, and from the first power generation unit. In the power supply system in which power can be sold by reversely flowing the power of the power to the AC supply source via the AC wiring, the AC wiring is connected to the AC load with the power generated using fuel. Second power generation means supplied via the output power, output power control means for controlling output power supplied from the first power generation means and the second power generation means to the AC load and the AC supply source, and the reverse power flow When it is determined that it is necessary to suppress the generated power, the gist of the invention is that it includes a control unit that preferentially suppresses the output power of the second power generation unit through the output power control unit.

  According to this configuration, when it is determined that it is necessary to suppress the power that flows backward, the output power of the second power generation means is preferentially suppressed through the control of the output power control means. Accordingly, the power supplied from the second power generation means is suppressed, and the consumption of fuel can be suppressed. Accordingly, it is possible to suppress the power that flows backward while maintaining the power generation efficiency without suppressing the power generated from the first power generation means.

  According to a second aspect of the present invention, in the power supply system according to the first aspect, the power supply system further includes a voltage detection unit that detects a received voltage of the AC load and outputs a detection result to the control unit. Determining that it is necessary to suppress the reverse power flow when the received voltage is equal to or higher than a threshold value set based on a voltage allowed to be supplied to the AC load, The gist of the invention is to make the received voltage less than the threshold value by preferentially suppressing the output power of the means.

  The voltage supplied from the AC supply source is set in advance to be slightly higher than the voltage supplied to the AC load in consideration of a drop due to the influence of the impedance of the AC wiring until power is supplied to the AC load. . When power is reversely flowed to the AC supply source side, the voltage of the AC wiring rises due to the influence of the impedance. Excessive voltage rise is undesirable for AC load operation. Therefore, when the control unit determines that the power reception voltage is equal to or higher than the threshold value based on the detection result of the voltage detection unit, the control unit suppresses the output power of the second power generation unit, thereby reducing the power reception voltage. Is less than the threshold. Thereby, the raise of a receiving voltage can be suppressed, maintaining the electric power generation efficiency from a 1st electric power generation means.

  The invention according to claim 3 is the power supply system according to claim 1 or 2, further comprising a storage battery for supplying AC power based on stored power to the AC load via the AC wiring, and the output power control means. Controls the output power supplied from the storage battery to the AC load and the AC supply source, and the control unit determines that it is necessary to suppress the power that is reversely flowed. The gist is to preferentially suppress the output power of the storage battery through the output power control means when it is determined that there is no output power from the power generation means.

  According to the configuration, when it is determined that it is necessary to suppress the power that is reversely flowed, and when it is determined that there is no output power from the first power generation unit, priority is given to the first power generation unit. And the electric power from a storage battery is suppressed. Therefore, the power supplied from the storage battery is suppressed, and consumption of the stored amount can be suppressed. Accordingly, it is possible to suppress the power that flows backward while maintaining the power generation efficiency without suppressing the power generated from the first power generation means.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power made to flow backward can be suppressed in a power supply system, maintaining the electric power generation efficiency of the electric power generation means using natural energy.

The block diagram which shows the structure of the electric power supply system in this embodiment. The block diagram which expanded a part of FIG. 1 in this embodiment. The block diagram which showed the structure of the converter in this embodiment. The flowchart which showed the process sequence of the voltage control program in this embodiment. The block diagram which shows the structure of the conventional power supply system.

Hereinafter, a power supply system according to the present invention will be described in detail with reference to FIGS.
As shown in FIG. 1, a house is provided with a power supply system 1 that supplies power to various devices (such as lighting devices, air conditioners, home appliances, and audiovisual devices) installed in the house. The power supply system 1 operates various devices using a commercial AC power source (AC power source) 2 for home use as well as the power of a solar cell 3 that generates power by sunlight and a fuel cell 4 that generates power by an electrical chemical reaction. Supply power to various devices. The power supply system 1 supplies power to an AC device 6 that operates by inputting an AC power supply (AC power supply) in addition to a DC device 5 that operates by inputting a DC power supply (DC power supply).

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

  An AC distribution board 11 for branching an AC power supply is connected to the control unit 7 via a cross flow connection line 12. An AC power source 2 is connected to the AC distribution board 11 via AC power lines 49 and 50. Between the AC power lines 49 and 50, a pole transformer 67 that boosts the power from the AC power source 2 is provided. The AC distribution board 11 is connected to an AC device 6 via an AC power line 48.

  The control unit 7 is connected to the solar cell 3 via the DC power line 13. In addition, the fuel cell 4 is connected to the control unit 7 via a DC power line 16 and the storage battery 23 is connected via a DC power line 15. The control unit 7 takes in AC power from the AC distribution board 11 and DC power from the solar cell 3, the fuel cell 4 and the storage battery 23, and converts these powers into predetermined DC power as a device power source. Then, the control unit 7 outputs the converted DC power to the DC distribution board 8 via the DC power line 14 or outputs it to the storage battery 23 via the DC power line 15 to store the same power. To do. The control unit 7 can not only take AC power from the AC distribution board 11 but also convert the power of the solar cell 3, the fuel cell 4 and the storage battery 23 into AC power and supply it to the AC distribution board 11. is there. The control unit 7 exchanges data with the DC distribution board 8 via the signal line 17. The solar cell 3 corresponds to a first power generation means using natural energy, and the fuel cell 4 corresponds to a second power generation means using fuel.

  The DC distribution board 8 is a kind of breaker that supports DC power. The DC distribution board 8 branches the DC power input from the control unit 7 and outputs the branched DC power to the control unit 9 via the DC power line 18 or relays via the DC power line 19. Or output to the unit 10. Further, the DC distribution board 8 exchanges data with the control unit 9 via the signal line 20 and exchanges data with the relay unit 10 via the signal line 21.

  A plurality of DC devices 5 are connected to the control unit 9. These DC devices 5 are connected to the control unit 9 via a DC supply line 22 that can carry both DC power and data by a pair of lines. The DC supply line 22 superimposes a communication signal for transmitting data by a high-frequency carrier wave on a DC voltage serving as a power source for the DC device 5, so that both the power and the data are supplied to the DC device through a pair of wires. 5 to transport. The control unit 9 acquires the DC power supply of the DC device 5 via the DC power line 18 and controls which DC device 5 based on the operation command obtained from the DC distribution board 8 via the signal line 20. Know what to do. Then, the control unit 9 controls the operation of the DC device 5 by outputting a DC voltage and an operation command to the instructed DC device 5 via the DC supply line 22.

  A switch 46 that is operated when switching the operation of the DC device 5 in the house is connected to the control unit 9 via the DC supply line 22. In addition, a sensor 45 that detects a radio wave transmitted from an infrared remote controller, for example, is connected to the control unit 9 via a DC supply line 22. Therefore, not only the operation instruction from the DC distribution board 8 but also the operation of the switch 46 and the detection of the sensor 45 cause the communication signal to flow through the DC supply line 22 to control the DC device 5.

  A plurality of DC devices 5 are connected to the relay unit 10 via individual DC power lines 25, respectively. The relay unit 10 acquires the DC power supply of the DC device 5 through the DC power line 19 and determines which DC device 5 is to be operated based on an operation command obtained from the DC distribution board 8 through the signal line 21. To grasp. The relay unit 10 controls the operation of the DC device 5 by turning on / off the power supply to the DC power line 25 with respect to the instructed DC device 5 using a built-in relay. In addition, a plurality of switches 26 for manually operating the DC device 5 are connected to the relay unit 10, and the DC power line 25 is turned on and off by the relay by operating the switch 26, thereby enabling the DC unit 5 to operate the DC unit 5. The device 5 is controlled.

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

  The AC power line 49 between the AC power source 2 and the AC distribution board 11 is provided with a power meter 29 that can remotely measure the amount of AC power source 2 used. The power meter 29 is equipped with not only a function of remote meter reading of the amount of commercial power used, but also a function of power line carrier communication and wireless communication, for example. The power meter 29 transmits the meter reading result to an electric power company or the like via power line carrier communication or wireless communication.

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

  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. For example, a gas / water meter 39 capable of remotely metering the amount of gas used or the amount of water used is connected to the control box 36 and also connected to the operation panel 40 of the network system 30. The operation panel 40 is connected to a monitoring device 41 including, for example, a door phone slave, a sensor, and a camera.

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

Next, a specific configuration around the control unit 7 and the AC distribution board 11 will be described.
As shown in FIG. 2, the control unit 7 includes a control unit 51, first to third DC / DC converters (hereinafter referred to as first to third converters) 55 to 57, and a bidirectional converter 58.

  The first converter 55 converts the DC power input from the solar cell 3 side into appropriate DC power and outputs the DC power to the DC distribution board 8 and the bidirectional converter 58 side. Similarly, the second converter 56 converts DC power input from the fuel cell 4 into appropriate DC power, and the third converter 57 converts DC power input from the storage battery 23 into appropriate DC power. , Respectively, to the DC distribution board 8 and the bidirectional converter 58 side.

  Specifically, as shown in FIG. 3, the first to third converters 55 to 57 include an input voltage detection circuit 61 that detects a voltage value on the input side, and an output voltage detection circuit 62 that detects a voltage value on the output side. The output current detection circuit 63 that detects the current value on the output side, the power circuit 64 for power conversion, and the CPU 65 that controls the power circuit 64.

  Based on a control signal from the CPU 65, the power circuit 64 converts the power into appropriate power and outputs it. The power circuit 64 includes a plurality of switch elements and the like. Further, the CPU 65 outputs detection results of the input voltage detection circuit 61, the output voltage detection circuit 62, and the output current detection circuit 63 to the control unit 51. The control unit 51 calculates output power from the power circuit 64 based on the detection results of the input voltage detection circuit 61, the output voltage detection circuit 62, and the output current detection circuit 63, and controls the first to third converters 55 to 57. Control. That is, the control part 51 controls the output power of the 1st-3rd converters 55-57 by outputting the command signal regarding output power to the 1st-3rd converters 55-57. In addition, the control unit 51 includes a nonvolatile memory 51a, and a voltage control program, a threshold value, and the like described later are stored in the memory 51a.

  As shown in FIG. 2, the bidirectional converter 58 provided in the cross flow connection line 12 converts the power from the DC power lines 13 to 16 into AC and converts the power from the AC power line 49 into DC. Thus, by providing the bidirectional converter 58 in the cross-flow connection line 12, the AC power is converted into DC power and transmitted to the DC power lines 13 to 16, or the DC power is converted into AC power and the AC system is converted. The power lines 48 and 49 can be transmitted. Further, the bidirectional converter 58 includes an input voltage detection circuit 61, an output voltage detection circuit 62, a CPU 65, an output current detection circuit 63, and the like, as in the configurations of the first to third converters 55 to 57 shown in FIG. A power circuit 64 that enables bidirectional power conversion between AC and DC is provided. That is, the bidirectional converter 58 can detect the voltage output to the AC power line 49 side through the output voltage detection circuit 62.

  Here, when the amount of power generated by the solar cell 3 exceeds the amount of power used by the DC device 5, DC power is converted into AC power to supply power to the AC device 6, or power that is a supply source of the AC power source 2. You can sell electricity by supplying power back to the company. Therefore, the electricity bill of the power company can be reduced.

  As shown in FIG. 2, the AC distribution board 11 includes a breaker 60 provided corresponding to each AC device 6. The breaker 60 is normally turned on and permits power transmission to the AC device 6. In addition, when it is detected that an overcurrent greater than or equal to a preset current value has flowed through the AC power line 48, the breaker 60 is turned off to cut off power transmission to the AC device 6. Thereby, for example, when the AC power line 48 is short-circuited, the accompanying heat generation of the AC power line 48 can be suppressed.

  The AC power line 49 has a power receiving point 66 where the power from the AC power source 2 and the power converted from the DC system into AC are merged. The power reception point 66 is a connection point between the cross flow connection line 12 and the AC power line 49. The AC device 6 receives the same voltage as the voltage Vr (power reception voltage) at the power reception point 66 via the AC power line 48. Bidirectional converter 58 detects voltage Vr at power receiving point 66 and outputs the detection result to control unit 51.

  Here, the electric power from the AC power source 2 is transmitted from substations installed in various places. Therefore, a voltage drop due to the impedance of the AC power line 50 during power transmission is unavoidable. In the same manner as described above, a voltage drop occurs due to the influence of the impedance of the AC power lines 48 and 49 during power transmission from the pole transformer 67 to the AC device 6. For such a voltage drop, a measure is taken to set the supply voltage from the AC power supply 2 and the voltage on the output side of the pole transformer 67 (AC device 6 side) higher.

  As described in the background art above, in the 100V system, the allowable voltage fluctuation is set to 101 ± 6V. In the 100V system, for example, the output voltage of the pole transformer 67 is set to 105V, which is a little higher, considering the voltage drop. Therefore, even when a voltage drop of 4 V occurs in the AC power lines 48 and 49, a voltage of about 101 V can be applied to the AC device 6.

  By the way, when selling the electric power generated from the solar cell 3 or the like, it is reversely flowed to the AC power source 2 through the AC power line 49, the pole transformer 67, and the AC power line 50. At this time, the voltage at the power receiving point 66 rises due to the influence of the impedance of the AC power lines 49 and 50. In other words, when a reverse power flow is made to the AC power source 2, it is necessary to supply high voltage power in consideration of the impedance of the AC power lines 49 and 50.

  In such a case, the control unit 51 executes the processing procedure shown in the flowchart of FIG. 4 in order to decrease the voltage Vr at the power receiving point 66. This flow is executed according to the voltage control program stored in the memory 51a. The voltage control program is created from the viewpoint of suppressing the voltage Vr and effectively using power.

  The control unit 51 constantly monitors the voltage Vr at the power receiving point 66 (precisely, at a predetermined control cycle). That is, the control unit 51 recognizes the voltage Vr through the detection result of the bidirectional converter 58, and compares this voltage Vr with the threshold value Va stored in its own memory 51a (S101). For example, in the case of a 100V system, the threshold value Va is set based on the maximum voltage 107V allowed to be applied to the AC device 6.

  When the voltage Vr at the power receiving point 66 is less than the threshold value Va (NO in S101), it is assumed that the power is normally supplied to the AC device 6 or is reversely flowed to the AC power source 2. Ends the process.

  When the voltage Vr at the power receiving point 66 is equal to or higher than the threshold value Va (YES in S101), the control unit 51 performs control to decrease the voltage Vr, assuming that the allowable maximum voltage may be exceeded. Specifically, first, the control unit 51 determines whether or not the output power Pout of the second converter 56 is an approximate value of zero (output power Pout≈0) (S102). Here, even if no power is supplied from the fuel cell 4, the second converter 56 is connected to various electronic devices, and therefore, it is conceivable that the output power Pout thereof does not become completely zero. That is, the approximate value of zero is set so as to include a minute current that is not electric power from the fuel cell 4. In this example, the approximate value of zero is a concept including zero (output power Pout = 0).

  When the output power Pout from the second converter 56 does not approximate zero (NO in S102), the power from the fuel cell 4 is being supplied to the second converter 56. In this state, control unit 51 outputs a command signal for decreasing output power Pout to second converter 56 (S103). As shown in FIG. 3, the CPU 65 that has received this command signal performs control to reduce the output power Pout from the power circuit 64. Here, as shown in FIG. 2, since the output power Pout from the first to third converters 55 to 57 is supplied to the power receiving point 66, the voltage Vr is supplied from the first to third converters 55 to 57. It is determined based on the output power Pout. Therefore, the voltage Vr decreases as the output power Pout from the second converter 56 decreases.

  On the other hand, as shown in FIG. 4, when the output power Pout from the second converter 56 is close to zero (YES in S102), the power from the fuel cell 4 is not supplied. That is, the voltage Vr in this state is derived from the power from the solar cell 3 and the storage battery 23. In this case, the control unit 51 determines whether or not the output power Pout from the third converter 57 is close to zero (S104). When the output power Pout from the third converter 57 does not approximate zero (NO in S104), power is being supplied from the storage battery 23. In this state, the control unit 51 outputs a command signal for decreasing the output power Pout to the third converter 57 (S105). Similarly to the second converter 56, the third converter 57 receives the command signal and decreases the output power Pout. As a result, the voltage Vr at the power receiving point 66 decreases.

  On the other hand, when the output power Pout from the third converter 57 is close to zero (YES in S104), the power is not supplied from the storage battery 23. That is, the voltage Vr in this state is derived from the electric power from the solar cell 3. In this case, the control unit 51 outputs a command signal for reducing the output power Pout to the first converter 55 (S106). Similar to the second converter 56, the first converter 55 receives the command signal and decreases the output power Pout. As a result, the voltage Vr at the power receiving point 66 decreases.

  Thus, when the electric power from the fuel cell 4 is used, the electric power from the fuel cell 4 is decreased and the voltage Vr is decreased. Further, when the power from the fuel cell 4 is not used, the power from the storage battery 23 is decreased to decrease the voltage Vr. Thereby, consumption of the fuel of the fuel cell 4 and the amount of electricity stored in the storage battery 23 can be suppressed.

  Then, the control unit 51 compares the voltage Vr and the threshold value Va again (S107). When the voltage Vr at the power receiving point 66 is equal to or higher than the threshold value Va (YES in S107), the control unit 51 returns to the process of step S102 and determines whether or not the output power Pout of the second converter 56 approximates zero. Determine whether. When the output power Pout of the second converter 56 is not close to zero (NO in S102), a command signal for reducing the output power Pout is output to the second converter, and the output power Pout of the second converter 56 is output. Is approximately zero (YES in S102), it is determined whether or not the output power Pout of the third converter 57 approximates zero (S104). Thus, the above process is repeated until the voltage Vr at the power receiving point 66 becomes less than the threshold value Va. When the voltage Vr is less than the threshold value Va (NO in S107), the voltage control program process is terminated, assuming that the voltage Vr at the power receiving point 66 is not more than the allowable maximum voltage. Thereby, it is suppressed that the voltage exceeding the allowable maximum voltage is applied to the power receiving point 66, and thus the AC device 6.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) When it is determined that it is necessary to suppress the power that flows backward, that is, when the voltage Vr at the power receiving point 66 becomes equal to or higher than the threshold value Va, the fuel cell 4 is controlled through the control of the second converter 56. The output power of is preferentially suppressed. Therefore, the power supplied from the fuel cell 4 is suppressed, and the consumption of fuel can be suppressed. Thereby, it is possible to suppress the power that is reversely flowed while maintaining the power generation efficiency without suppressing the power generated from the solar cell 3.

  (2) Considering that the voltage supplied from the AC power source 2 drops due to the impedance of the AC power line 50 before power is supplied to the AC device 6, the voltage supplied to the AC device 6 in advance. It is set a little higher. When the power is made to flow backward to the AC power supply 2 side, the voltage of the AC power line 50 rises due to the influence of the impedance. An excessive voltage increase is not preferable for the operation of the AC device 6. Therefore, when the control unit 51 determines that the voltage Vr at the power receiving point 66 detected by the bidirectional converter 58 is equal to or higher than the threshold value Va, the output power of the fuel cell 4 is output through the second converter 56. By suppressing the voltage Vr, the voltage Vr at the power receiving point 66 is made less than the threshold value Va. Thereby, the raise of the voltage Vr can be suppressed, maintaining the electric power generation efficiency from the solar cell 3. FIG.

  (3) When it is determined that it is necessary to suppress the power that flows backward, and when it is determined that there is no output power from the solar cell 3, the power from the storage battery 23 is given priority over the solar cell 3. Suppress power. Therefore, the electric power supplied from the storage battery 23 is suppressed and consumption of the amount of stored electricity can be suppressed. Thereby, it is possible to suppress the power that is reversely flowed while maintaining the power generation efficiency without suppressing the power generated from the solar cell 3.

In addition, the said embodiment can be implemented with the following forms which changed this suitably.
In the above embodiment, the bidirectional converter 58 is provided and the DC power system and the AC power system are linked, but an inverter may be provided instead of the bidirectional converter 58. The inverter converts DC power from the DC power line 14 into AC power and supplies the AC power to the AC power line 49.

  In the above embodiment, the output power of the first to third converters 55 to 57 is supplied to the bidirectional converter 58. However, the bidirectional converter 58 is omitted, and the solar cell 3, the fuel cell 4, and the storage battery are omitted. A power conditioner including a converter and an inverter may be provided on each output side of 23. The power conditioner converts DC power from the solar cell 3, the fuel cell 4 and the storage battery 23 into appropriate AC power and outputs it.

  -In the said embodiment, the structure which directly supplies the direct-current power from the solar cell 3, the fuel cell 4, and the storage battery 23, ie, the DC distribution board 8, the control unit 9, the relay unit 10, the DC apparatus 5, etc. are provided. However, these may be omitted and configured as an AC power supply system.

  In the above embodiment, the power from the solar cell 3, the fuel cell 4, and the storage battery 23 is supplied to the AC device 6 and the DC device 5, but the storage battery 23 may be omitted. Even in this case, by suppressing the output power Pout of the second converter 56 supplied from the fuel cell 4 in preference to the solar cell 3, the voltage Vr at the power receiving point 66 can be reduced without reducing the generated power of the solar cell 3. Can be suppressed.

  In the above embodiment, the solar battery 3 that generates power based on solar energy is provided as the first power generation means that uses natural energy. However, the power generation means that uses natural energy is not limited to this, for example, Wind power generation, geothermal power generation, or the like may be used.

  In the above-described embodiment, the case where the voltage at the power receiving point 66 increases at the time of power sale is assumed as the case where it is necessary to suppress the power flowing in the reverse direction due to the impedance of the AC power lines 48 and 49. However, the present invention is not limited to this as long as it is necessary to suppress the reverse power flow. As a case where it is necessary to suppress the power flowing in the reverse direction, for example, the following situation can be considered. Assume that when the electric power from the solar battery 3 is sold and the electric power from the storage battery 23 and the fuel cell 4 is supplied to the AC device 6, the charge control is performed because the storage amount of the storage battery 23 is reduced. In such a situation, the control unit 51 suppresses the power that is reversely flowed, and executes control to spend that much power for charging the storage battery 23. In this case, the control unit 51 suppresses the output power Pout of the second converter 56 corresponding to the fuel cell 4 without suppressing the power from the solar cell 3 in order to suppress the reverse power flow. Then, by supplying a part of the power from the solar cell 3 to the AC device 6, the reverse power flow is suppressed and the power supplied to the AC device 6 can be maintained.

  In the above embodiment, the first to third converters 55 to 57 are provided as output power control means. However, it is not limited to the converter as long as the electric power from the solar cell 3, the fuel cell 4, and the storage battery 23 can be controlled. For example, a switching element that switches on / off power transmission from the solar cell 3, the fuel cell 4, and the storage battery 23 to the bidirectional converter 58 and the DC distribution board 8 may be used. Also in this configuration, when the voltage Vr at the power receiving point 66 is equal to or higher than the threshold value Va, first, the switching element corresponding to the fuel cell 4 is turned off, and then the switching element corresponding to the storage battery 23 is turned off. While maintaining the power generation efficiency of the solar cell 3, the voltage at the power receiving point 66 is suppressed.

  DESCRIPTION OF SYMBOLS 1 ... Electric power supply system, 2 ... AC power supply (commercial AC power supply, AC supply source), 3 ... Solar cell (1st electric power generation means), 4 ... Fuel cell (2nd electric power generation means), 7 ... Control unit, 12 ... cross-flow connection line, 13 to 16 ... DC system power line, 23 ... storage battery, 48 to 50 ... AC system power line (AC wiring), 51 ... control unit, 51a ... memory, 55 to 57 ... first to third converters ( Output power control means), 58 ... Bidirectional converter (voltage detection means), 61 ... Input voltage detection circuit, 62 ... Output voltage detection circuit, 63 ... Output current detection circuit, 64 ... Power circuit, 65 ... CPU, 66 ... Power reception Point, 67 ... A pole transformer.

Claims (3)

AC power is supplied to the AC load from the first power generation means and the AC supply source for generating power using natural energy via the AC wiring, and the power from the first power generation means is supplied via the AC wiring. In the power supply system in which power can be sold by making the AC power source flow backward
Second power generation means for supplying electric power generated using fuel to the AC load via the AC wiring;
Output power control means for controlling output power supplied from the first power generation means and the second power generation means to the AC load and the AC supply source;
And a control unit that preferentially suppresses the output power of the second power generation unit through the output power control unit when it is determined that the reverse flow power needs to be suppressed. The power supply system according to claim 1,
While detecting the received voltage of the AC load, the voltage detection means for outputting the detection result to the control unit,
The control unit determines that it is necessary to suppress the power that is reversely flowed when the power reception voltage is equal to or higher than a threshold value set based on a voltage that is allowed to be supplied to the AC load. 2. The power supply system according to claim 1, wherein the power reception voltage is less than the threshold value by preferentially suppressing output power of the second power generation means. The power supply system according to claim 1 or 2,
A storage battery for supplying AC power based on stored power to the AC load via the AC wiring;
The output power control means controls output power supplied from the storage battery to the AC load and the AC supply source,
When the control unit determines that there is a need to suppress the reverse power flow, and determines that there is no output power from the second power generation unit, the output power control unit, A power supply system that preferentially suppresses the output power of the storage battery.

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