JP2000092720A - Distributed power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch an output from a linkage operation output to a self- operation output when the abnormal voltage decline of a power system which is caused by a power supply interruption, an instantaneous voltage decline, etc., occurs, and keep on feeding a power to a load by cutting off the power system while a short break, etc., is avoided. SOLUTION: A linkage protective relay 13 (linkage protector) which outputs a system abnormality detection signal when the voltage decline of a power system occurs; a semiconductor switching circuit 16 which is provided between the system 8 and a load 10, and turned on or off in accordance with the existence of the detection signal; a linkage operation side inverter 1 which converts a DC power into an AC power by a linkage operation, and outputs the power in a normal system state wherein the switching circuit 16 is in an on-state and stops the operation when the voltage decline detection signal is inputted; and a self-operation side inverter 2 which converts a DC power into an AC power by a self-operation, and supplies the power to the load 10 cut off from the system 8 when the detection signal is inputted; are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed power supply device operated by a DC power supply such as a solar cell and a fuel cell.

[0002]

2. Description of the Related Art Conventionally, in a distributed power supply of this type such as a photovoltaic power generation system, when a power outage occurs, the operation shifts from an interconnected operation to an independent operation and continues to supply power to an important load (emergency load). Therefore, as shown in FIG. 7, there is a power conditioner provided with an inverter device 1 on the interconnection operation side and an inverter device 2 on the independent operation side as a power conditioner.

The conventional apparatus shown in FIG. 7 includes a solar cell 3 as a DC power supply. The DC power of the solar cell 3 is constantly supplied to the inverter 1 via a diode 4 for preventing backflow. The power is also supplied to the inverter device 2 via a DC-powered switch 5 composed of contacts of an electromagnetic contactor.

[0004] A battery 6 is provided on the input side of the inverter device 2 as an auxiliary power supply, and the battery 6 ensures the input of the inverter device 2 at the time of system power failure or at night.

Next, the output side of the inverter device 1 is connected to a power system 8 via a switch 7 for interconnection and disconnection, and at the same time, to an important load 10 via a switch 9 for interconnection power supply. It is connected.

The output side of the inverter device 2 is connected to an important load 10 via a switch 11 for independent power supply.

Further, an interconnection protection relay 13 as an interconnection protection device is connected to the electric power system 8 via an instrument transformer 12, and this relay 13 monitors and detects overvoltage, undervoltage and the like of the electric power system 8. , The system power supply 14 is disconnected from the power system 8,
When a failure or lightning damage of the general load 15 occurs and the voltage of the power system 8 drops due to a power failure or the like, a detection signal of a system abnormality is output immediately.

When the detection signal is not output and the system is normal, the switches 7 and 9 are turned on and the switch 11 is turned off. At this time, the inverter device 1 is operated in a linked state and the maximum power point tracking control ( Pmax control), the maximum power is extracted from the solar cell 3 and converted into AC power synchronized with the system power supply 14, and this AC power is transferred to the load 1 via the switches 7 and 9.
Power is supplied to 5,10.

Next, when a power failure or the like occurs in the power system 8 and its voltage decreases, a detection signal of a system abnormality is immediately output from the interconnection protection relay 13, and the switches 7, 9 are turned off by the detection signal. As a result, the switches 5, 11 are turned on, the inverter device 1 is stopped, and the inverter device 2 is operated independently.

At this time, when the switches 7, 9 are turned off, the inverter 1, the power system 8, and the important load 10 are disconnected.
The inverter device 2 generates AC power controlled at a constant voltage by the CVCF operation by the self-sustaining operation.
Is supplied to the load 10 via the.

The turning on and off of the switches 5, 7, 9, 11 and the starting and stopping of the inverter devices 1 and 2 are actually performed by
This is performed by sequence control or the like based on the detection signal of the interconnection protection relay 13.

When a voltage drop occurs in the power system 8, the inverter device 1 is first stopped, and then the switches 7, 9 are turned off, and the switches 5, 11 are turned on.

Thereafter, the independent operation of the inverter device 2 is started, and even when the power system 8 loses power due to the independent operation, power supply to the load 10 is continued.

By the way, when the power failure of the power system 8 is restored and the system returns to normal again, the detection signal is no longer detected from the interconnection protection relay 13, and the switches 5, 11 are turned off, and the switches 7, 11 are turned off. 9 turns on, the inverter device 2 stops, and the inverter device 1 starts the interconnection operation again.

[0015]

In the case of the conventional apparatus shown in FIG. 7, a power outage or the like of the power system 8 occurs, and the interconnection protection relay 1 is turned off.
When switching from the interconnected operation output of the inverter device 1 to the independent operation output of the inverter device 2 by the detection signal of the system abnormality of 3, the switches 5, 7, 9, 11 mechanically switch the power supply path, Load 1 disconnected from power system 8
There is a problem that power supply to 0 is instantaneously interrupted.

For this reason, conventionally, only a load which does not cause any trouble even if a momentary interruption of the power supply occurs in the load 10 can be selected, and it is not possible to use a computer device or the like as an important load to realize the uninterruptible power supply.

According to the present invention, when a system abnormality such as a power failure or a voltage drop such as an instantaneous voltage drop occurs, an instantaneous interruption or the like due to switching of a power supply path does not occur, and a connection operation output is changed to an independent operation output. It is another object of the present invention to enable switching and power supply to a load disconnected from a power system to be continued.

[0018]

In order to solve the above-mentioned problems, a distributed power supply according to the present invention detects a voltage drop such as a power outage or an instantaneous voltage drop in a power system in the case of claim 1. An interconnection protection device that outputs a detection signal of a system abnormality,
Provided between the power system and the load, having the detection signal,
A first semiconductor switch circuit such as a thyristor switch circuit that switches from on to off and vice versa,
The output side is connected to a connection point between the load and the semiconductor switch circuit, and when the system in which the semiconductor switch circuit is turned on is normal, the DC power supply is converted into AC power and output by interconnecting operation, and the detection signal is output when the voltage drop occurs. An inverter device on the connection protection operation side stopped by an input, and an output side connected to the connection point, and when the voltage drop occurs, the self-sustaining operation is performed by the input of the detection signal to convert the DC power supply into AC power;
And an inverter device on the independent operation side for supplying power to a load disconnected from the power system.

Therefore, when the system is normal, the semiconductor switch circuit is turned on, and the inverter device on the connection operation side is connected to the power system via this switch circuit.

At this time, the load is connected to the power system via the semiconductor switch circuit, and is supplied with power from the inverter device and the power system on the interconnection operation side.

Next, when a voltage drop such as a power failure occurs in the power system, a detection signal of a system abnormality is output from the interconnection protection device, and the detection signal causes the inverter device on the interconnection operation side to stop and the self-sustaining operation side to stop. Is switched to the self-sustained operation of the inverter device, and the AC operation of the inverter device on the independent operation side is supplied to the load.

At this time, the semiconductor switch circuit is instantaneously turned off by an electronic switching operation in response to a detection signal of a system abnormality of the interconnection protection device, and a load power supply instantaneous like a conventional device accompanying a mechanical switching operation of a switch. No interruption or the like occurs, and power supply to the load disconnected from the power system is continued without an instantaneous interruption or the like.

When the power system recovers from a power failure or the like, a detection signal of a system abnormality is not output from the interconnection protection device, the inverter device on the independent operation side is stopped, the semiconductor switch circuit is turned on, and the interconnection operation side is turned off. The linked operation of the inverter device is restarted, and the linked device returns to the linked operation without an instantaneous interruption of the load power supply.

According to a second aspect of the present invention, there is provided an interconnection protection device for detecting a voltage drop such as a power failure or an instantaneous voltage drop of a power system and outputting a detection signal of a system abnormality, and a method for connecting a power system and a load. A first semiconductor switch circuit such as a thyristor switch circuit that switches from on to off and vice versa depending on the presence or absence of the detection signal, and one end connected to a connection point between the load and the first semiconductor switch circuit. A second semiconductor switch circuit such as a thyristor switch circuit that switches from on to off and vice versa in conjunction with the first semiconductor switch circuit depending on the presence or absence of the detection signal; and a second semiconductor switch circuit on the output side. Is connected to the other end of the switch, and both semiconductor switch circuits are turned on. When the system is operating normally, the inverter is connected to the inverter and the current power is converted to AC power and output. A converter device for taking out the maximum power from the DC power supply but it switched to the converter operation by an input of the detection signal upon the occurrence of the voltage drop off,
An inverter having an output side connected to the connection point and, when the voltage drop occurs, being operated independently by inputting the detection signal to convert a DC output of the converter device into AC power and supplying power to the load disconnected from a power system Device.

Therefore, when the system is normal, both the semiconductor switch circuits are turned on. At this time, the converter device corresponding to the inverter device on the interconnection operation side in claim 1 is interconnected by the inverter operation. In the same manner as in the case (1), the load is supplied from the converter device and the power system.

Next, when a voltage drop such as a power failure occurs in the power system and a detection signal of a system abnormality is output from the interconnection protection device, the first semiconductor switch circuit is turned off by the detection signal, and the load and the load are reduced. The converter device and the inverter device are separated from the power system.

Further, the second semiconductor switch circuit is turned off by the detection signal, and the output side of the converter device is disconnected from the load and the output side of the inverter device.

Further, the converter device is switched from the inverter device operation to the converter operation in response to the input of the detection signal, and the maximum power is extracted from the DC power supply by the converter operation.

Then, the DC output of the maximum power of the converter device is supplied to the inverter device, and the AC power of the inverter device for independent operation is supplied to the load.

In this case, the two semiconductor switch circuits are instantaneously turned off by the electronic switching operation, and the load power supply is continued without an instantaneous interruption or the like accompanying the switching of the power supply path.

In addition, since the maximum power is extracted from the DC power supply by the converter device and supplied to the inverter device, the power of the DC power supply is reduced particularly when the DC power supply is a power supply whose output fluctuates every moment, such as a solar cell. It is possible to supply the load of the self-sustained operation output by using as much as possible.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
This will be described with reference to FIG. (1) One embodiment of the present invention corresponding to claim 1 will be described with reference to FIGS. In FIG. 1, the same reference numerals as those in FIG. 7 denote the same or corresponding components, and the difference from the conventional device in FIG. 7 is that the switches 7, 9, 11 in FIG.
7 between the connection point between the output side of the inverter device 1 on the interconnection operation side and the load 10 and the power system 8.
Is that the semiconductor switch circuit 16 is provided at the position (1), and the output side of the inverter device 2 on the independent operation side is directly connected to the load 10.

The semiconductor switch circuit 16 is composed of an anti-parallel circuit of the thyristors 16a and 16b. When the system is normal, a detection signal of a system abnormality is not input from the interconnection protection relay 13, so that the voltage of the thyristors 16a and 16b becomes zero. It is turned on by the synchronized ignition, and the inverter device 1 and the load 10 on the interconnection operation side are connected to the electric power system 8 (interconnection).

At this time, the inverter device 1 is connected to the system power supply 1
4, the DC power of the solar cell 3 is converted into AC power synchronized with the system power supply 14 by Pmax control, and this power is supplied to the loads 10 and 15.

Next, when a power failure such as a power failure or an instantaneous voltage drop occurs in the power system 8, a system failure such as that shown in FIG.
₁ , the interconnection protection relay 13 detects a voltage drop of the power system 8 and outputs a system abnormality detection signal. The detection signal is input to the inverter devices 1 and 2, the switch 5, and the semiconductor switch circuit 16.

[0036] Then, based on the input of the detection signal of the voltage drop, the inverter device 1, as shown in Step A ₂ in Figure 2 stops the interconnected operation.

At the same time, as shown in steps A ₃ and A ₄ , the switch 5 is turned on, and the inverter device 2 starts an independent operation.

[0038] Further, the input by the thyristors 16a of the semiconductor switch 16 system abnormality detection signal, the arc is stopped point 16b, turned off instantaneously as shown in Step A ₅ of FIG inverter device 1 and the load 10 to power system 8
Disconnect from

[0039] Then, the load 10 is disconnected from the power system 8, as shown in Step A _6, AC power autonomous operation of the inverter apparatus 2 is powered, the power supply of the load 10 is continued.

At this time, the change of the electronic switching operation of the semiconductor switch circuit 16 from ON to OFF is much faster than in the case of the conventional mechanical switching of the switches 7, 9, and 11.
The power supply to the load 10 is not interrupted by the switching of the semiconductor switch circuit 16, and the power supply to the load 10 is continuously continued without an instantaneous interruption due to the switching of the power supply path.

Next, the power failure power system 8, back to the system successfully returns from the instantaneous voltage drop or the like, for example, as shown in the operation sequence of the power failure recovery in FIG 4, interconnection protection relay 13 in step B ₁ Stops detecting a system abnormality and the detection signal is turned off.

When this detection signal is turned off, step B
_2, as shown in B _3, the inverter apparatus 2 stops autonomous operation, switch 5 is turned off.

[0043] Further, as shown in Step _{B 4,} instantaneously turned on the semiconductor switch circuit 16 to resume thyristor 16a, ignition of the 17b, the inverter device 1 and the load 1
0 is connected to the power system 8 again.

[0044] Then, the inverter device 1, as shown in Step B ₆ is operated again interconnection, the AC power is fed to the load 10, 15.

Therefore, in the case of this embodiment, when a voltage drop such as a power failure of the power system 8 occurs with a simple and inexpensive configuration provided with one semiconductor switch circuit 16, instantaneous interruption or the like accompanying switching of the power supply path occurs. Further, the power supply of the load 10 can be continued by switching the distributed power supply from the interconnected operation output to the independent operation output.

Since the semiconductor switch circuit 16 is electronically switched from on to off at high speed and vice versa, even when an instantaneous voltage drop of the power system 8 occurs, power supply to the load 10 is continued without an instantaneous interruption or the like. Thus, a so-called instantaneous voltage drop compensation function can be added to the distributed power supply device.

Therefore, stable uninterruptible power supply can be realized with a computer device or the like as an important load.

(Other Embodiment) Another embodiment of the present invention corresponding to claim 2 will be described with reference to FIGS. 4, the same reference numerals as those in FIG. 7 denote the same or corresponding components, and 17 denotes a converter device provided in place of the inverter device 1 in FIG. And a converter function at the time of self-sustaining operation is provided. The solar cell 3 is connected to the input side via the diode 4. 18
7 is an inverter device provided in place of the inverter device 2 in FIG. 7, and the CVCF operation is performed during the self-sustaining operation similarly to the inverter device 2. Reference numeral 19 denotes a DC power-supplying switch provided between the output side of the converter device 17 and the input side of the inverter device 18 instead of the switch 5 of FIG. And turns on during interconnection operation by a detection signal of a system abnormality of the interconnection protection relay 13.

Reference numeral 20 denotes a first semiconductor switch circuit provided at the position of the switch 7 in FIG. 7, that is, between the power system 8 and the load 10, and is connected to one end connected to the load 10 and the power system 8. Thyristors 20a, 20
0b is formed by providing an anti-parallel circuit of
The power supply 8 is turned off when a voltage drop occurs in the power system 8 due to the input of the detection signal of the system abnormality 3.

Reference numeral 21 denotes a semiconductor switch circuit 20 and a load 10
And a second semiconductor switch circuit provided between the connection point of the converter device 17 and the output side of the converter device 17. One end connected to the connection point of the semiconductor switch circuit 20 and the load 10 and the output side of the converter device 17 are provided. A thyristor 21a, a parallel circuit of 21b is provided between the connected other end, and formed.
When the voltage drop of the power system 8 occurs due to the input of the system abnormality detection signal of the interconnection protection relay 13, the semiconductor switch circuit 2
Turns off in conjunction with 0. In addition, each switch 5,7, of FIG.
9 and 11 are omitted.

When the system is normal, the semiconductor switch circuits 20 and 21 are connected to the thyristors 20a, 20b, 21a and 21.
b, and the load 10 is connected to the power system 8 via the semiconductor switch circuit 20, and the converter device 1
7 is the load 10, via the semiconductor switch circuits 20 and 21;
Connected to power system 8.

Further, since converter system 17 does not receive a system abnormality detection signal from interconnection protection relay 13, it is interconnected and operates as an inverter, and Pmax control similar to inverter device 1 in FIG. The maximum power is extracted and converted into AC power synchronized with the system power supply 14.

Then, the AC power for this interconnection operation is supplied from the converter device 17 to the loads 15 and 10 via the semiconductor switch circuits 20 and 21.

Next, a power failure to the power system, the voltage drop of such instantaneous voltage drop occurs, for example, as shown in operational sequence when a power failure occurs in FIG. 5, interconnection protection relay 13 the power system 8 by Step C ₁ And outputs a system abnormality detection signal.

[0055] By the input of the detection signal, the converter device 17 for switches in the converter operating from the inverter operation, temporarily stopped as shown in step C _2.

[0056] Also, the semiconductor switching circuit by an input of the detection signal of the system abnormality as shown in Step _{C 3} 20, 2
1 is switched from on to off, the load 10 is disconnected from the power system 8 by turning off the semiconductor switch circuit 20, and the output side of the converter device 17 is turned off from the load 10 and the output side of the inverter device 18 by turning off the semiconductor switch circuit 21. Be cut off.

[0057] Furthermore, the autonomous operation starts operating the inverter device 18 as shown in step C _4, at the same time,
Switch 19 as shown in step C ₅ is the output of the ON converter device 17 is connected to the input side of the inverter device 18.

[0058] Then, switches to the converter unit 17 is the converter operates as shown in Step C _6, the Pmax control operation of the converter operation, the converter apparatus 17 takes out the maximum power from the solar cell 3, via a switch 19 It is supplied to the inverter device 18.

[0059] Based on this supply, the inverter device 18 to form AC power autonomous operation, AC power of self-sustaining operation is fed to the load 10 from the inverter device 18 as shown in step C _7.

In this case, the semiconductor switch circuits 20, 21
The power supply of the load 10 is continued without an instantaneous interruption or the like as in the case of the first aspect.

Moreover, the converter device 17 is used for the solar cell 3
In order to extract the maximum power from the inverter and supply the power to the inverter device 18, the power of the solar cell 3 is used as effectively as possible, the consumption of the battery 6 is suppressed as much as possible, and the stable AC power based on the independent operation of the inverter device 18 is supplied to the load 10. Can be powered.

Next, the power failure power system 8, return from instantaneous voltage drop, etc. Returning to the system successfully, for example, as shown in the operation sequence of the power failure recovery in FIG 6, the interconnection protection relay 13 in step D ₁ The system abnormality detection signal turns off.

When this detection signal is turned off, step D
_2, as shown in D _3, the converter device 17 to stop the operation of the converter operation, also the inverter device 18 to stop the isolated operation.

Further, as shown in steps D ₄ and D ₅ , the semiconductor switch circuits 20 and 21 are turned on and the switch 19 is turned off, and the output side of the converter device 17 is again powered via the semiconductor switch circuits 21 and 20. Connected to system 8.

[0065] Then, the converter apparatus 17 as shown in step D ₆ is operated interconnection and inverter operation, feeding AC power interconnected operation to the load 15,10.

Therefore, in the case of this embodiment, since the converter device 17 having the inverter function and the converter function and the semiconductor switch circuits 20 and 21 are provided, when the voltage drop such as the power failure of the power system 8 occurs, the first embodiment is used.
As in the case of the embodiment, the power supply to the load 10 can be continued without an instantaneous interruption due to the switching of the power supply path, and the maximum power is taken out from the solar cell 3 by the converter operation of the converter device 17, and the power is used as much as possible. The power supply of the load 10 can be performed while suppressing the consumption of the battery 6.

By the way, in both of the above embodiments,
Although the case where the solar cell 3 is provided as the DC power supply has been described, it is needless to say that the present invention can be similarly applied to a case where another DC power generation device such as a fuel cell is provided as the DC power supply.

Then, the semiconductor switch circuits 16, 20,
Reference numeral 21 may be other than a thyristor switch circuit, and may be formed by, for example, a transistor switch circuit. Further, the interconnection protection relay 13 and the like are not limited to those of the above-described embodiments.

Further, for example, when applied to a three-phase system, the inverter devices 1, 2, 18, and the converter device 1
7, semiconductor switch circuits 16, 20, 21 and the like may be provided for each phase.

[0070]

The present invention has the following effects. First, in the case of claim 1, when a voltage drop such as a power failure occurs in the power system 8, an interconnection protection device (interconnection protection relay 1) is provided.
A detection signal of a system abnormality is output from 3), and the inverter 1 on the interconnecting operation side is stopped by this detection signal, the operation is switched to the independent operation of the inverter 2 on the independent operation side, and the operation shifts from the interconnected operation to the independent operation. Thus, the AC output of the inverter device 2 can be supplied to the load 10.

At this time, the semiconductor switch circuit 16 is instantaneously turned off by electronic switching in response to a system abnormality detection signal of the interconnection protection device, and instantaneous interruption of load power supply or the like caused by mechanical switching operation as in the conventional device is performed. The power supply to the load 10 disconnected from the power system 8 can be continued without occurrence.

When the power system recovers from a power failure or the like, a detection signal of a system abnormality is no longer output from the interconnection protection device, the inverter device 2 on the independent operation side is stopped, the semiconductor switch circuit 16 is turned on, and the interconnection is stopped. The interconnection operation of the inverter device 1 on the operation side is restarted, and the power supply state of the interconnection operation returns to the power supply state of the interconnection operation without any interruption of the load power supply.

Therefore, when a system abnormality such as a power failure or a voltage drop such as a momentary voltage drop occurs, the operation output is switched from the interconnected operation output to the self-sustained operation output so as not to cause an instantaneous interruption due to the switching of the power supply line. Power supply to the load 8 disconnected from the system 8 can be continued.

Then, the load 10 is protected against an instantaneous voltage drop.
Therefore, it is possible to provide a novel distributed power supply device having a so-called instantaneous voltage drop compensation function added thereto.

For this reason, the uninterruptible power supply can be realized by using a computer device or the like as an important load.

In the case of claim 2, when a voltage drop such as a power failure occurs in the power system 8 and a detection signal of a system abnormality is output from the interconnection protection device, the first semiconductor switch is used in accordance with the detection signal. The circuit 20 is turned off, and the load 10, the converter device 17, and the inverter device 18 are disconnected from the power system 8.

Further, the second semiconductor switch circuit 21 is turned off by the detection signal, and the output side of the converter device 17 is disconnected from the output side of the load 10 and the inverter device 18.

Further, the input of the detection signal causes the converter device 17 to switch from the inverter operation to the converter operation. The converter operation takes out the maximum power from the DC power supply, and the DC output of the maximum power is supplied to the inverter device 18. The AC power for the independent operation of the inverter device 18 is supplied to the load 10.

Then, the two semiconductor switch circuits 20, 21
Is instantaneously turned off by electronic switching, and switched from the interconnected operation output to the self-sustained operation output so as not to cause an instantaneous interruption or the like due to the switching of the power supply line, and cut off from the power system 8 as in the case of claim 1. Power supply to the separated load 10 can be continued.

Further, since the maximum power is extracted from the DC power supply by the converter device 17 and supplied to the inverter device 18, particularly when the DC power supply is a power supply such as a solar battery whose output fluctuates every moment, the DC power supply It is possible to use the electric power as effectively as possible to supply the load of the self-sustaining operation output.

[Brief description of the drawings]

FIG. 1 is a connection diagram of one embodiment of the present invention.

FIG. 2 is a flowchart for explaining an operation at the time of a power failure in FIG. 1;

FIG. 3 is a flowchart for explaining an operation at the time of restoration from a power failure in FIG. 1;

FIG. 4 is a connection diagram of another embodiment of the present invention.

FIG. 5 is a flowchart for explaining an operation at the time of a power failure in FIG. 4;

FIG. 6 is a flowchart for explaining an operation at the time of recovery from a power failure in FIG. 4;

FIG. 7 is a connection diagram of a conventional device.

[Explanation of symbols]

 1, 2, 18 Inverter device 3 Solar cell 8 Power system 10, 15 Load 13 Interconnection protection relay 16, 20, 21 Semiconductor switch circuit 17 Converter device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02M 7/48 H02M 7/48 N H01L 31/04 K 47 F-term (reference) in Nissin Electric Co., Ltd. FA01 FA02 FA12 FA13 FA14 FA19 GA09

Claims (2)

[Claims] The system has a function of an interconnection operation and an independent operation. When a transition is made from the interconnection operation to an independent operation, a DC power source such as a solar cell is converted into AC power and disconnected from the power system. In a distributed power supply device for supplying power to a load, an interconnection protection device that detects a voltage drop such as a power outage or an instantaneous voltage drop of the power system and outputs a detection signal of a system abnormality, and between the power system and the load. A semiconductor switch circuit such as a thyristor switch circuit that switches from on to off and vice versa depending on the presence or absence of the detection signal, and an output side connected to a connection point between the load and the semiconductor switch circuit, When the switch circuit is turned on, when the system is normal, the DC power supply is converted to AC power and output by the interconnection operation, and when the voltage drop occurs, the operation is stopped by the input of the detection signal. An inverter device, an output side of which is connected to the connection point, which is operated independently by the input of the detection signal when the voltage drop occurs, converts the DC power supply into AC power, and supplies the load to the load disconnected from the power system. A distributed power supply device comprising: a self-sustaining operation side inverter device for supplying power. 2. It has a function of interconnected operation and independent operation, and when a transition is made from interconnected operation to independent operation, a DC power source such as a solar cell is converted to AC power and disconnected from the power system. In a distributed power supply device for supplying power to a load, an interconnection protection device that detects a voltage drop such as a power outage or an instantaneous voltage drop of the power system and outputs a detection signal of a system abnormality, and between the power system and the load. A first semiconductor switch circuit such as a thyristor switch circuit that switches from on to off and vice versa depending on the presence or absence of the detection signal, and one end at a connection point between the load and the first semiconductor switch. A second semiconductor switch circuit such as a thyristor switch circuit that is connected and switches from on to off and vice versa in conjunction with the first semiconductor switch circuit depending on the presence or absence of the detection signal; The power side is connected to the other end of the second semiconductor switch circuit, and when the two semiconductor switch circuits are turned on, the current power supply is converted into AC power by the interconnection operation of the inverter operation and output when the system is normal. A converter device which switches to a converter operation by the input of the detection signal when the voltage drop at which the switch circuit is turned off to take out the maximum power from the DC power supply, and an output side is connected to the connection point, and when the voltage drop occurs, A distributed power supply, comprising: an inverter that is operated independently by the input of the detection signal, converts a DC output of the converter into AC power, and supplies power to the load disconnected from the power system. apparatus.