JP2022139330A - Distributed power supply system - Google Patents

Abstract

To provide a distributed power supply system which can supply normal voltage to a three-wire load when three-wire power is supplied to the three-wire load by combining a plurality of pieces of single-phase power to be individually output.SOLUTION: A distributed power supply system comprises: a power supply device which supplies DC power; a plurality of power conditioners which convert the DC power input from the power supply device into single-phase AC; and an output terminal connected with a single-phase load which is a power supply object and a commercial power system, and supplies power to the load by predetermined output voltage. The plurality of power conditioners are connected in parallel with one another, and power is supplied to the same single-phase load in a linkage operation with the commercial power system, and power by three-wire voltage is supplied to the three-wire load by blocking connection with the single-phase load and combining output with different phases of the plurality of power conditioners to simultaneously supply power to the three-wire load in an autonomous operation.SELECTED DRAWING: Figure 1

Description

The present invention relates to a distributed power supply system with multiple inverters.

In the past, distributed power sources such as storage batteries and solar cells were installed, and in normal times, the distributed power sources were connected to the commercial power system to supply power to single-phase loads, and the power supply from the commercial power system was interrupted due to power outages. A distributed power supply system has been proposed that can supply power from a plurality of distributed power supplies to a three-phase load when the system is stopped due to a power failure (see, for example, Patent Document 1).

However, when a plurality of distributed power sources are combined in this way to supply three-phase power through three wires, there is a problem that proper three-phase power cannot be obtained if the power of each phase is output separately. .

Japanese Patent No. 4340668

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. An object of the present invention is to provide a distributed power supply system capable of supplying voltage.

The present invention for solving the above problems is
Connected to a power supply device that supplies DC power, a plurality of power conditioners that convert the DC power input from the power supply device into single-phase AC power, and a single-phase load that is to be supplied with power and a commercial power system and a distributed power supply system for supplying power to the single-phase load with a predetermined output voltage,
During interconnected operation with the commercial power system, the plurality of power conditioners are connected in parallel and power is supplied to the same single-phase load,
During the self-sustained operation, the connection with the single-phase load is cut off, and the outputs of the plurality of power conditioners with different phases are combined to simultaneously supply power to the three-line load, so that the three-line voltage is applied to the three-line load. It is characterized by supplying electric power.

According to this, in a distributed power supply system that supplies three-wire voltages generated by combining the outputs of a plurality of power conditioners with different phases to three-wire loads, the output of each power conditioner is simultaneously applied to the three-wire loads. supplied. Therefore, it is possible to supply the normal three-wire voltage with all the phases to the three-wire load without supplying the three-wire load with an incorrect three-wire voltage such as the voltage of a part of the phase is missing.
Various distributed power sources such as storage batteries, solar cells, and fuel cells can be applied as the power supply device.

Moreover, in the present invention,
An electric circuit opening/closing unit may be provided for simultaneously connecting electric circuits connecting the plurality of power conditioners and the three-wire loads.

According to this, by connecting the electric circuit opening/closing unit, the outputs of the plurality of power conditioners with different phases can be simultaneously supplied to the three-wire load, so that the normal three-wire voltage can be supplied to the three-wire load. can be done. Such an electric circuit opening/closing unit may be provided outside the plurality of power conditioners, or may be provided inside the plurality of power conditioners.

Moreover, in the present invention,
Each of the plurality of power conditioners may supply the power of the three-line voltage to the three-line load based on the information indicating the timing of supplying the out-of-phase outputs.

In this way, each of the plurality of power conditioners supplies the power of the three-line voltage to the three-line load based on the information instructing the timing of supplying the outputs with different phases. voltages can be supplied at the same time. Therefore, the normal three-wire voltage can be supplied to the three-wire load.
In addition, in the power supply by the voltage of the three wires to the load of the three wires, a three-phase three-wire system power supply is possible by outputting the voltage of the three wires with the phase difference of 120°. A single-phase three-wire power supply can also be realized with the same configuration by outputting.

According to the present invention, there is provided a distributed power supply system capable of supplying a normal voltage to a three-wire load when supplying three-wire power to a three-wire load by combining a plurality of individually output single-phase powers. can.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the distributed power supply system which concerns on Example 1 of this invention. FIG. 4 is a relationship diagram of three-phase voltages according to Embodiment 1 of the present invention; 4 is a flow chart showing a procedure of three-phase output timing control according to Embodiment 1 of the present invention; It is a figure which shows schematic structure of the distributed power supply system which concerns on Example 2 of this invention. FIG. 5 is a diagram showing a three-phase output timing control method according to Embodiment 2 of the present invention; FIG. 3 is a diagram showing a schematic configuration of a distributed power supply system according to Example 3 of the present invention; FIG. 10 is a flow chart showing a procedure of three-phase output timing control according to Example 3 of the present invention; FIG.

[Example of application]
Hereinafter, application examples of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a distributed power supply system 1 according to an application example of the present invention.
The distributed power supply system 1 includes two single-phase first power conditioners 20a and second power conditioners 20b connected to two storage batteries 7a and 7b, respectively. The first power conditioner 20a and the second power conditioner 20b respectively have a single-phase first inverter 10a and a second inverter 10b. In this example, the output of the first inverter 10a and the second inverter 10b is the single-phase output of the first inverter 10a and the second inverter 10b by connecting the relays 5a and 5b and the relays 5c and 5d when the system is connected. Electric power by voltage is supplied to consumer loads 2 and 3 . On the other hand, during self-sustained operation, the relays 9a, 9b, and 9c of the external relay 9 are connected, and the relay SW6a, 6b, and 6c are connected to the power conditioners 20a and 20b, so that the outputs of the first inverter 10a and the second inverter 10b are is connected to the three-phase isolated operation load 8 .

During self-sustained operation, a 120-degree phase difference is provided between the output voltages of the first inverter 10a and the second inverter 10b to generate a three-phase voltage and supply three-phase, three-wire power.

When voltages with different phases are output from the two power conditioners in this way, there is a possibility that three-phase voltages will not be output normally. Therefore, in the distributed power supply system 1, the external relay 9 is provided, and the output timing of the three-phase voltage from the two power conditioners as shown in FIG. 3 is controlled.
It is obvious that the output voltages of the first inverter 10a and the second inverter 10b are provided with a phase difference of 180 degrees to obtain a single-phase three-wire voltage output.

First, the first inverter 10a and the second inverter 10b start preparing for self-sustained operation (step S1), and the first inverter 10a starts self-sustained operation output (step S2). The second inverter 10b waits for completion of synchronization with the isolated operation output of the first inverter 10a (step S3). At this stage, the relays SW6a, 6b, 6c are connected to the power conditioners 20a, 20b, but the relays 9a, 9b, 9c of the external relay 9 are not connected.

Next, the first inverter 10a starts self-sustained operation output (step S2), and the second inverter 10b waits for completion of synchronization with the self-sustained operation output of the first inverter 10a (step S3). Then, when the synchronization of the second inverter 10b with the first inverter 10a is completed, the second inverter 10b starts self-sustained operation output (step S4). At this stage, the second inverter 10b transmits a relay drive signal to the external relay 9, and by connecting the relays 9a, 9b, and 9c (step S5), the three-phase voltage generated by the first inverter 10a and the second inverter 10b is , to the self-sustaining operation load 8 (step S6).

As described above, in the distributed power supply system 1, after the outputs of the first inverter 10a and the second inverter 10b are synchronized and a normal three-phase voltage can be generated, the external relay 9 is operated to Improper voltage application can be prevented by applying a three-phase voltage to .

[Example 1]
Below, the distributed power supply system 1 according to the first embodiment of the present invention will be described in more detail with reference to the drawings.

The distributed power supply system 1 in this embodiment includes two single-phase first power conditioners 20a and second power conditioners 20b connected to two storage batteries 7a and 7b, respectively, which are examples of power supply devices. It is The first power conditioner 20a and the second power conditioner 20b respectively have a single-phase first inverter 10a and a second inverter 10b. In this example, the outputs of the first inverter 10a and the second inverter 10b are output to the single-phase commercial power system 1a and the single-phase consumer loads 2 and 3 via relays 5a and 5b and relays 5c and 5d. 17, 18 and 19 are connected. Also, the output from the three-phase commercial power system 1b is connected to the three-phase isolated operation load 8 by connecting the relay SW6a, 6b, and 6c to the system side. Outputs of the first inverter 10a and the second inverter 10b are output via relays 9a, 9b, and 9c of an external relay 9 provided outside the first inverter 10a and the second inverter 10b, and relay SW6a, 6b, and 6c. It is connected to a three-phase isolated operation load 8 as a three-phase load. Then, by connecting the relays 5a and 5b and the relays 5c and 5d, the electric power by the single-phase voltage of the first inverter 10a and the second inverter 10b is supplied to the consumer loads 2 and 3. On the other hand, relays 9a, 9b, and 9c are connected, and relay SW6a, 6b, and 6c are connected to the power conditioners 20a and 20b, so that the output of the first inverter 10a and the second inverter 10b becomes a three-phase isolated operation load. 8 is connected. That is, relays 9a, 9b, and 9c of an external relay 9, which is an example of an electric circuit opening/closing unit, are provided in the electric circuit connecting the first inverter 10a, the second inverter 10b, and the self-supporting operation load 8. FIG. The relays 9a, 9b, and 9c of the external relay 9 are connected or disconnected by an external relay drive signal transmitted from the second inverter 10b. The external relay 9 can be installed, for example, in a distribution board.

During interconnected operation with the commercial power system, the relays 5a and 5b and the relays 5c and 5d are connected so that the electric power from the single-phase voltage of the first inverter 10a and the second inverter 10b is supplied to the consumer load. 2 and 3 are supplied. On the other hand, during self-sustained operation, the relays 9a, 9b, and 9c are connected, and the relay SW6a, 6b, and 6c are connected to the inverter side, so that the power generated by the output voltage of the first inverter 10a and the second inverter 10b is , is supplied to the islanding load 8 . In the present embodiment, during this self-sustained operation, the output voltages of the first inverter 10a and the second inverter 10b are provided with a phase difference of 120 degrees to generate a three-phase voltage, thereby generating a three-phase three-wire power supply. supply. By providing a phase difference of 180 degrees between the output voltages of the first inverter 10a and the second inverter 10b, a single-phase three-wire voltage output is obtained (the same applies to the second and third embodiments). ).

FIG. 2 shows a relationship diagram of three-phase voltage. As shown in FIG. 2A, in this embodiment, the first inverter 10a outputs the first-phase output voltage V1, and the second-phase output voltage V1 is delayed by 120 degrees from the first inverter 10a and the second inverter 10b. Output voltage V2. By outputting an output voltage of V3=-(V1+V2), the third phase output can generate an output voltage delayed by 120 degrees from V2.

In the distributed power supply system 1, the output voltage from the first inverter 10a is input to the second inverter 10b and its value is measured. Based on the measured value, the first inverter 10b generates and outputs an output voltage V2 whose phase is delayed by 120 degrees with respect to the output voltage V1 from the first inverter 10a. With such a configuration, a three-phase voltage is generated by combining and synchronizing the single-phase voltages of the two first inverters 10a and the second inverter 10b, and power is supplied to the three-phase self-sustaining operation load 8 during self-sustaining operation. do.

FIG. 3 shows a procedure of three-phase output timing control in the distributed power supply system 1. As shown in FIG.
First, the first inverter 10a and the second inverter 10b start preparing for the self-sustained operation by detecting the stoppage of the grid power or receiving the self-sustained operation instruction from the host device (step S1). At this stage, the relays SW6a, 6b, 6c are connected to the power conditioners 20a, 20b, but the relays 9a, 9b, 9c of the external relay 9 are not connected.

Next, the first inverter 10a starts self-sustained operation output (step S2). As described above, the relays 9 a , 9 b , 9 c of the external relay 9 are not connected, so the self-sustained operation output of the first inverter 10 a is not supplied to the self-sustained operation load 8 .

Next, the second inverter 10b waits for completion of synchronization with the self-sustained operation output of the first inverter 10a (step S3). As described above, since the output voltage from the first inverter 10a is input to the second inverter 10b, the second inverter 10b determines whether or not synchronization with the self-sustained operation output of the first inverter 10a has been completed. Judgment is possible.

When the synchronization of the second inverter 10b with the first inverter 10a is completed, the second inverter 10b starts self-sustained operation output (step S4).

Then, the second inverter 10b transmits a relay drive signal to the external relay 9 to connect the relays 9a, 9b and 9c (step S5).
As a result, the three-phase voltages generated by the first inverter 10a and the second inverter 10b are simultaneously applied to the self-supporting operation load 8 (step S6).

As described above, in the distributed power supply system 1, after the outputs of the first inverter 10a and the second inverter 10b are synchronized and a normal three-phase voltage can be generated, the external relay 9 is operated to By applying a three-phase voltage to , it is possible to prevent improper voltage application and supply the self-sustaining operation load 8 with power based on a normal three-phase voltage.

[Example 2]
A distributed power supply system 11 according to a second embodiment of the present invention will be described below. FIG. 4 shows a schematic configuration of the distributed power supply system 11. As shown in FIG. Configurations similar to those of the distributed power supply system 1 according to the first embodiment are denoted by similar reference numerals, and detailed description thereof is omitted.

In the distributed power supply system 11, a synchronization signal is transmitted from the first inverter 10a to the second inverter 10b, and communication is performed between the first inverter 10a and the second inverter 10b.

A three-phase output timing control method in the distributed power supply system 11 will be described with reference to FIG. In FIG. 5, the solid line indicates the output voltage V1 from the first inverter 10a, the dashed line indicates the output voltage V2 from the second inverter 10b, and the dashed line indicates the output voltage V3 generated by -(V1+V2). . Here, the first inverter 10a transmits the output voltage V1 and a synchronization signal (a pulse signal that turns on when V1 becomes 0) to the second inverter 10b. After the phases of the output voltage V2 of the second inverter 10b and the output of the output voltage V1 of the first inverter 10a are synchronized based on the synchronization signal, the first inverter 10a communicates with the second inverter 10b at the output start timing. send information about Assuming that the time indicated by the dotted line in FIG. 5 is the output start timing, the first inverter 10a and the second inverter 10b simultaneously start output based on this output start timing information. As a result, three-phase voltage can be applied to the self-sustained operation load 8 at the same time, and power can be supplied to the self-sustained operation load 8 at normal three-phase voltage.

Here, the information on the output start timing is an example of information that instructs the timing of supplying the outputs with different phases. Such output start timing information is not limited to the case where it is transmitted from the first inverter 10a to the second inverter 10b as described above. It may be transmitted to the first inverter 10a and the second inverter 10b.

[Example 3]
A distributed power supply system 21 according to a third embodiment of the present invention will be described below. FIG. 6 shows a schematic configuration of the distributed power supply system 21. As shown in FIG. Configurations similar to those of the distributed power supply system 1 according to the first embodiment are denoted by similar reference numerals, and detailed description thereof is omitted.

In the distributed power supply system 21, the first inverter 10a and the second inverter 10b are provided with internal relays 12 and 13, respectively. That is, in the distributed power supply system 21, the outputs of the first inverter 10a and the second inverter 10b are relays 12a and 12b provided inside the first inverter 10a, relays 13a provided inside the second inverter 10b, 13b and relay SW6a, 6b, 6c to a three-phase self-sustaining operation load 8. Therefore, the relays 12a, 12b and the relays 13a, 13b are connected, and the relay SW6a, 6b, 6c is connected to the power conditioners 20a, 20b, so that the outputs of the first inverter 10a and the second inverter 10b are three-phase. It is connected to the self-sustaining operation load 8 . That is, the electric circuit connecting the first inverter 10a, the second inverter 10b, and the self-supporting operation load 8 includes internal relays 12, relays 12a and 12b, and an internal relay 13, which are examples of electric circuit opening/closing units.
relays 13a and 13b are provided.

Further, in the distributed power supply system 21, similarly to the distributed power supply system 11 according to the second embodiment, the synchronization signal is transmitted from the first inverter 10a to the second inverter 10b, and the first inverter 10a and the second inverter 10b are transmitted. 2 Communication is performed with the inverter 10b.

FIG. 7 shows the procedure of three-phase output timing control in the distributed power supply system 21. As shown in FIG. The same symbols are used for the same processing as the procedure of the three-phase output timing control in the distributed power supply system 1, and the description is omitted.
First, similarly to the distributed power supply system 1, the distributed power supply system 21 also starts preparation for self-sustained operation (step S1). At this stage, the relays SW6a, 6b, 6c are connected to the power conditioners 20a, 20b, but the relays 12a, 12b of the internal relay 12 and the relays 12a, 12b of the internal relay 13 are not connected.

Steps S2 and S4 of the three-phase output timing control are the same as in the distributed power supply system 1, but in the distributed power supply system 21, when waiting for the completion of synchronization of the second inverter 10b in step S13, as described above, Based on the synchronization signal transmitted from the first inverter 10a, the phase of the output voltage of the second inverter 10b is synchronized with the phase of the output voltage of the first inverter 10a.

When the self-sustained operation output of the second inverter 10b is started (step S4), the first inverter 10a transmits the ON timing information of the internal relay 13 to the second inverter 10b by communication. The internal relays 12 and 13 are simultaneously turned on based on the information on the internal relay ON timing (step S15). As a result, the three-phase voltages generated by the first inverter 10a and the second inverter 10b are simultaneously applied to the self-supporting operation load 8 (step S6).

As described above, in the distributed power supply system 21, after the outputs of the first inverter 10a and the second inverter 10b are synchronized and a normal three-phase voltage can be generated, the internal relays 12 and 13 are operated to By applying the three-phase voltage to the self-sustaining operation load 8, it is possible to prevent improper voltage application and to supply the self-sustaining operation load 8 with normal three-phase voltage.

<Appendix 1>
A power supply device (7a, 7b) that supplies DC power, a plurality of power conditioners (20a, 20b) that convert the DC power input from the power supply device into single-phase AC power, and a power supply target In a distributed power supply system (1) comprising single-phase loads (2, 3) and outputs (17, 18, 19) connected to the commercial power system and supplying power to said loads with a predetermined output voltage There is
During interconnected operation with the commercial power system, the plurality of power conditioners (20a, 20b) are connected in parallel to supply power to the same single-phase loads (2, 3),
During self-sustained operation, the connection with the single-phase loads (2, 3) is cut off, and the outputs of the plurality of power conditioners (20a, 20b) with different phases are combined to simultaneously supply power to the three-wire load (8). A distributed power supply system, characterized in that power is supplied to the loads of the three wires by the voltage of the three wires.

Reference Signs List 1: distributed power supply system 2, 3: single-phase loads 7a, 7b: storage battery 8: independent operation loads 17, 18, 19: output terminals 20a, 20b: power conditioner

Claims (7)

Connected to a power supply device that supplies DC power, a plurality of power conditioners that convert the DC power input from the power supply device into single-phase AC power, and a single-phase load that is to be supplied with power and a commercial power system and a distributed power supply system for supplying power to the single-phase load with a predetermined output voltage,
During interconnected operation with the commercial power system, the plurality of power conditioners are connected in parallel and power is supplied to the same single-phase load,
During the self-sustained operation, the connection with the single-phase load is cut off, and the outputs of the plurality of power conditioners with different phases are combined to simultaneously supply power to the three-line load, so that the three-line voltage is applied to the three-line load. A distributed power supply system characterized by supplying electric power. 2. The distributed power supply system according to claim 1, further comprising an electric circuit switching unit for simultaneously connecting electric circuits connecting said plurality of power conditioners and said three-line loads. 3. The distributed power supply system according to claim 2, wherein the electric circuit switching unit is provided outside the plurality of power conditioners. 3. The distributed power supply system according to claim 2, wherein the electric circuit switching unit is provided inside the plurality of power conditioners. 2. The power conditioner according to claim 1, wherein each of the plurality of power conditioners supplies the three-line voltage power to the three-line load based on the information indicating the timing of supplying the outputs with different phases. distributed power system. 6. The distributed power supply system according to any one of claims 1 to 5, wherein the three-wire voltage power supply to the three-wire load is based on a three-phase three-wire system. 6. The distributed power supply system according to any one of claims 1 to 5, wherein the power supply of the three-wire voltage to the three-wire load is by a single-phase three-wire system.

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