JP7265702B2 - power system - Google Patents

Description

The present invention relates to power supply systems.

As a conventional power supply system, as shown in Patent Document 1, it has a function as an uninterruptible power supply system that supplies power to important loads in the event of an abnormality in the commercial power system (uninterruptible power supply function), and a continuous power supply system for the commercial power system. Some of them are configured to use a common distributed power source to achieve both a function (load leveling function) as a distributed power source system for load leveling by power flow and reverse power flow.

This power supply system connects the commercial power system and the distributed power supply in order to satisfy the so-called FRT (Failure to Continue Operation) requirement, which allows the distributed power supply to continue operating without being disconnected from the commercial power system during a momentary sag. An open/close switch is provided on the power line, and an impedance element is connected in parallel to the open/close switch.

With such a configuration, even if the on-off switch is opened during a momentary sag, the distributed power supply is connected to the commercial power system via the impedance element, so while satisfying the FRT requirements of the distributed power supply, the uninterruptible power supply function and A load leveling function can be compatible.

By the way, the use of distributed power sources as regular power generators may not be economically justifiable, for example, when the peak cut/peak shift effect of distributed power sources is reduced due to an increase in the fuel cost of distributed power sources. .

Even in such a case, as a method of using a distributed power supply, there is a method of using it as an emergency power generator while connected to the commercial power system.

However, as described above, when an impedance element is connected in parallel with the on-off switch, as shown in FIG. When the opening/closing switch is opened during a momentary sag, the distributed power supply and the commercial power system are interconnected via the impedance element. As a result, unnecessary current flows from the distributed power supply to a load other than the important load connected to the commercial power system, resulting in loss and heat.

Japanese Patent No. 6338131

Therefore, the present invention has been made to solve the above problems, and when using a distributed power supply as a regular power generator, while satisfying the FRT requirements, when using the distributed power supply as an emergency power generator The main object of the present invention is to suppress the generation of unnecessary current at the time of voltage sag.

That is, a power supply system according to the present invention includes: a distributed power supply connected to a commercial power system; a first open/close switch provided on a power line connecting the commercial power system and the distributed power supply; a parallel-connected impedance element; a grid-side voltage detector that detects a voltage on the commercial power grid side of the first opening/closing switch; A power supply system comprising: a first control unit that opens the first opening/closing switch and connects the distributed power supply and the commercial power system via the impedance element when the first open/close switch is closed.
In this power supply system, a second open/close switch connected in parallel to the first open/close switch and connected in series to the impedance element indicates whether the distributed power supply is in an operating state or a stopped state. A second control that acquires a state signal, closes the second opening/closing switch when the state signal indicates the operating state, and opens the second opening/closing switch when the state signal indicates the stopped state. It is characterized by further comprising a part.

In such a power supply system, the impedance element is connected in parallel to the first open/close switch, and the first open/close switch is opened when the voltage on the commercial power system side falls below the set value. In this case as well, the distributed power supply is connected to the commercial power system via the impedance element. As a result, the FRT requirements can be satisfied while the load leveling function is exhibited by using the distributed power supply as a regular power generator.
Moreover, since the second opening/closing switch is connected in parallel with the first opening/closing switch and is connected in series with the impedance element, the second opening/closing switch is closed when the distributed power supply is in operation as a regular power generator. Then, while satisfying the FRT requirements as described above, when the distributed power supply is in a stopped state, that is, when the distributed power supply is provided as an emergency generator, the second open/close switch is opened. , it is possible to prevent the generation of unnecessary current at the moment of voltage drop.

In a parallel circuit having the first opening/closing switch and the second opening/closing switch, when both switches are closed, a current flows through the first opening/closing switch side circuit in which the impedance element is not provided, and the impedance element is provided. No current flows through the second on-off switch side circuit that is closed. Therefore, when the state signal indicates the stopped state, the second control section can open the second opening/closing switch in a state in which current does not flow through the second opening/closing switch.
With such a configuration, since the second opening/closing switch is opened in advance before the momentary sag occurs, generation of unnecessary current during the momentary sag can be reliably suppressed.

In this way, when opening the second opening/closing switch before the momentary sag occurs, it is sufficient to open the second opening/closing switch at an appropriate timing in a state where no current is flowing. is not necessary, and a relatively inexpensive mechanical switch can be used. Also, even when semiconductor switches using semiconductor elements without self-extinguishing capability, such as thyristors, are connected in parallel, they can be opened in a timely manner while no current is flowing before the momentary sag occurs. Therefore, there is no need to provide a forced arc-extinguishing function, and the switch can be constructed at a relatively low cost.

As a specific aspect for automating the control of the second open/close switch, the second control unit is input to the distributed power source, and switches the distributed power source to the operating state or the stopped state. /OFF signal, an operating signal output from the distributed power source to indicate whether the distributed power source is in the operating state or the stopped state, or for switching the operating state or the stopped state of the distributed power source One or more of the time elapsing signals output from the timer are acquired as the state signals.

As a specific aspect of the distributed power supply, electricity is generated using fuel and heat utilization equipment that uses the waste heat, or an uninterruptible power supply that can operate including reverse power flow to the commercial power system. apparatus.

According to the present invention configured in this way, when the distributed power source is used as a regular power generator, the FRT requirements are satisfied, and when the distributed power source is used as an emergency power generator, the Generation of unnecessary current can be suppressed.

1 is a schematic diagram showing the configuration of a power supply system according to a first embodiment; FIG. FIG. 2 is a schematic diagram showing the state of the power supply system when distributed power sources are in operation during normal operation according to the first embodiment; FIG. 3 is a schematic diagram showing the state of the power supply system when distributed power sources are in operation during an instantaneous sag according to the first embodiment; FIG. 4 is a schematic diagram showing the operation of the power supply system when the distributed power sources of the first embodiment are in a stopped state; FIG. 4 is a schematic diagram showing the state of the power supply system when distributed power sources are in a stopped state during normal operation according to the first embodiment; FIG. 4 is a schematic diagram showing the state of the power supply system when distributed power supplies are in a stopped state during an instantaneous sag according to the first embodiment; It is a schematic diagram which shows the structure of the power supply system in the modification of 1st Embodiment. It is a schematic diagram which shows the structure of the power supply system of 2nd Embodiment. It is a schematic diagram which shows the structure of the power supply system of 3rd Embodiment. It is a table|surface which shows the list of the operation state of 3rd Embodiment. It is a schematic diagram which shows the structure of the power supply system of 3rd Embodiment. FIG. 10 is a schematic diagram for explaining unnecessary current flowing in a conventional configuration;

<First embodiment>
A first embodiment of a power supply system according to the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the power supply system 100 of the present embodiment is provided between the commercial power system 10 and the important load 30, and supplies power to the important load 30 when the commercial power system 10 malfunctions. function (uninterruptible power supply function) and a function (load leveling function) as a distributed power supply system that levels the load by forward and reverse power flow to the commercial power system 10 .

Here, the commercial power system 10 is a power supply network of an electric power company (electric utility), and has a power plant, a power transmission system, and a power distribution system. Further, the important load 30 is a load to which electric power should be stably supplied even in the event of a system abnormality such as a power failure or a momentary voltage drop. In addition, one or more general loads 40 other than the critical loads 30 are also connected to the commercial power system 10 .

Specifically, the power supply system 100 includes an uninterruptible power supply (UPS) 1, a distributed power supply 2, a parallel-off switch 3 for paralleling off the commercial power system 10 and the distributed power supply 2, and a commercial power system 10, the distributed power supply 2, and the important load 30, an impedance element 5 connected in parallel to the first open/close switch 4; It comprises a grid-side voltage detector 6 that detects voltage, and a first controller 7 that opens the first open/close switch 4 when the voltage detected by the grid-side voltage detector 6 becomes equal to or less than a set value.

In this embodiment, the uninterruptible power supply 1 has a power storage device (power storage device) 11 such as a secondary battery (storage battery) and a power conversion device 12, and stops when the commercial power system 10 is in a healthy state. state, and in an abnormal state of the trademark power system 10, it becomes an operating state.

Distributed power supply 2 is connected to power line L<b>1 for supplying power from commercial power system 10 to important load 30 . This distributed power source 2 is interconnected to the commercial power system 10, and is called cogeneration or monogeneration, which is a heat utilization facility 21a using fuel, for example. The heat utilization equipment 21a uses, for example, gas or petroleum as a fuel to generate electricity with an engine, a turbine, a fuel cell, or the like, and utilizes the exhaust heat. In addition, as the distributed power source 2, there is a DC power generation facility such as a solar power generation or a fuel cell and a power conversion device (not shown), and an electric energy output by an AC such as a wind power generation or a micro gas turbine is converted into a DC power source. A power generation facility (not shown) that is connected to the grid using a power converter after rectification, or an AC power generation facility (not shown) such as a synchronous generator or an induction generator. One or more of these may be provided.

The parallel-off switch 3 is, for example, a mechanical switch provided closer to the commercial power system 10 than the connection point of the distributed power source 2 on the power line L1. The parallel-off switch 3 is controlled to open and close by the first control unit 7, which will be described later, and is opened when a predetermined parallel-off condition is satisfied.

The first open/close switch 4 opens and closes the power line L1, and may be an open/close switch capable of high-speed switching, such as a semiconductor switch or a hybrid switch combining a semiconductor switch and a mechanical switch. For example, when a semiconductor switch is used, the switching time can be set to 2 ms or less, and the power can be cut off regardless of the zero point. Moreover, when a hybrid switch is used, the switching time can be reduced to 2 msec or less, and not only is it possible to cut off regardless of the zero point, but also the conduction loss can be reduced to zero. The opening/closing of the first opening/closing switch 4 is controlled by the first controller 7 .

The impedance element 5 is connected in parallel to the first open/close switch 4 on the power line L1, and is a current limiting reactor in this embodiment. A parallel circuit composed of the first open/close switch 4 and the impedance element 5 is provided closer to the important load 30 than the general load 40 described above.

The system-side voltage detection unit 6 detects the voltage on the commercial power system 10 side of the power line L1 from the first open/close switch 4 via the voltage transformer. Specifically, the grid-side voltage detector 6 is connected to the commercial power grid 10 side of the parallel circuit composed of the first open/close switch 4 and the impedance element 5 via a voltage transformer.

The first control unit 7 compares the detected voltage detected by the grid-side voltage detection unit 6 with a predetermined set value, and if the detected voltage is equal to or less than the set value, the first open/close switch 4 to open the first open/close switch 4 by outputting a control signal to . Note that the set value in this embodiment is a voltage value for detecting a voltage drop. By opening the first open/close switch 4 by the first control unit 7 in this way, the commercial power system 10 , the distributed power supply 2 and the important load 30 are connected via the impedance element 5 . In this state, the distributed power source 2 continues operation including reverse power flow.

In this way, when the distributed power source 2 operates including reverse power flow, it is possible to achieve peak cut/peak shift by the distributed power source 2. A leveling function is exhibited.
However, if the cost of fuel used in the heat utilization equipment 21a, which is the distributed power source 2, increases, the effect of peak cut/peak shift decreases. Therefore, in such a case, the distributed power supply 2 of the present embodiment is kept in a stopped state while being connected to the commercial power system 10, and is used as an emergency power generator.

In the configuration described above, the power supply system 100 of the present embodiment includes a second open/close switch 8 connected in parallel to the first open/close switch 4 and connected in series to the impedance element 5, and the second open/close switch 8 connected in series to the impedance element 5. and a second control unit 9 for controlling.

The second open/close switch 8 opens and closes the second power line L2 for connecting the impedance element 5 in parallel to the first open/close switch 4 provided on the power line L1, in other words, the second power line L2 provided with the impedance element 5. It is something to do. In this embodiment, the second open/close switch 8 is provided closer to the commercial power system 10 than the impedance element 5 in the power line L2. can be used.

The second control unit 9 acquires a state signal indicating whether the distributed power source 2 is in an operating state or a stopped state, and when the state signal indicates the operating state, closes the second opening/closing switch 8, The second opening/closing switch 8 is opened when the state signal indicates the stop state.
Here, when the distributed power source 2 is in operation, this distributed power source 2 is used as a regular power generator that continues to operate including reverse power flow. On the other hand, when the distributed power supply 2 is in a stopped state, this distributed power supply 2 is provided as an emergency power generator. That is, the second control unit 9 closes the second opening/closing switch 8 when the dispersed power source 2 is used as a regular power generator, and closes the second open/close switch 8 when the distributed power source 2 is provided as an emergency power generator. opens the second open/close switch 8 .
The second control unit 9 may be a function performed by a common CPU with the first control unit 7, or may be a function performed by a CPU different from the first control unit 7. .

The second control unit 9 of the present embodiment acquires, as the above-described state signal, an operation signal output from the distributed power source 2 and indicating whether the distributed power source 2 is in an operating state or a stopped state, It is configured to determine whether the distributed power source 2 is in an operating state or in a stopped state.
As another aspect of the second control unit 9, for example, an ON/OFF signal that is input to the distributed power source 2 and switches the distributed power source 2 to an operating state or a stopped state may be acquired as a state signal. Further, when the distributed power source 2 switches between an operating state and a stopped state according to, for example, a time period, the second control unit 9 outputs from a timer for switching between the operating state and the stopped state of the distributed power source 2. You may acquire the time-lapse signal which is shown as a state signal.

Next, the operation of the power supply system 100 of the present embodiment (normal time and momentary voltage drop) is divided into a case where the distributed power supply 2 serving as the heat utilization equipment 21a is used as a regular power generator and a case where it is used as an emergency power generator. , with reference to FIGS.

[When distributed power supply 2 is used as a regular power generator]
First, when the distributed power source 2 is used as a regular power generator, the above-described second control unit 9 determines that the distributed power source 2 is in an operating state, and closes the second open/close switch 8 .

In the state where the second open/close switch 8 is closed as described above, the power supply system 100 normally closes the first open/close switch 4 as shown in FIG. is a state of being connected to the commercial power system 10 via the first open/close switch 4 . Although the reactor 5 is connected in parallel to the first open/close switch 4, the impedance of the first open/close switch 4 is smaller than the impedance of the reactor 5. exchanges electric power on the first open/close switch 4 side. In this state, peak cut/peak shift can be realized by reverse power flow by the dispersed power source 2 .

On the other hand, when a short-circuit accident (for example, a three-phase short circuit) occurs on the commercial power system 10 side, the voltage on the commercial power system 10 side drops. This voltage drop is detected by the grid-side voltage detector 6 . The first control unit 7 opens the first opening/closing switch 4 when the detected voltage detected by the grid-side voltage detection unit 6 is equal to or lower than the set value. Then, the uninterruptible power supply 1 starts self-sustaining operation and supplies power to the important load 30 .

As shown in FIG. 3 , when the first open/close switch 4 is opened, the distributed power supply 2 and the important load 30 are connected to the commercial power system 10 via the reactor 5 . In this state, the current flowing from the distributed power supply 2 to the short-circuit fault point is limited by the reactor 5 to suppress the fault current flowing to the short-circuit fault point and prevent the voltage drop of the important load 30 . Further, in this state, the distributed power source 2 continues operation including reverse power flow, and continues power generation output.

Further, the first control unit 7 opens the parallel-off switch 3 when the voltage detected by the grid-side voltage detection unit 6 satisfies a predetermined parallel-off condition. The parallel-off condition here is that the duration of the voltage drop in the system voltage (state in which the detected voltage is equal to or lower than the set value) is equal to or longer than a predetermined value (longer than the sag duration). Since the selector switch 3 has already been released, the reactor 5 suppresses overcurrent due to the opening of the parallel-off switch 3 .

Note that the grid-side voltage detection unit 6 detects the voltage on the commercial power grid 10 side regardless of whether the first open/close switch 4 is open or closed, and the first control unit 7 detects the voltage detected by the grid-side voltage detection unit 6. is equal to or higher than a predetermined recovery voltage, for example, when the residual voltage of the commercial power system is equal to or higher than 80%, the first open/close switch 4 is closed.

Due to the operation of the power supply system 100 as described above, the voltage on the commercial power system 10 side becomes equal to or lower than the set value, and even when the first open/close switch 4 is opened, the distributed power supply 2 and the important load 30 are connected to the commercial power supply via the reactor 5 . A state of being connected to the power system 10 is established. Therefore, since the distributed power supply 2 and the important load 30 are not separated from the commercial power system 10 at any time during normal operation or momentary sag, when the distributed power supply 2 is used as a regular power generator, this distributed power supply While satisfying the FRT requirements imposed on the power supply 2, it is possible to prevent a voltage drop to the critical load 30 during a voltage sag. This makes it possible to achieve both an uninterruptible power supply function and a load leveling function.

[When the distributed power supply 2 is used as an emergency generator]
On the other hand, when the distributed power source 2 is used as an emergency power generator, as shown in FIG. 4, the above-described second control unit 9 determines that the distributed power source 2 is in a stopped state, and switches the second open/close switch. Release 8.

In the state where the second opening/closing switch 8 is opened in this manner, the power supply system 100 normally closes the first opening/closing switch 4 as shown in FIG. The heat utilization equipment 21a is connected to the commercial power system 10 and prepared for emergencies. Of course, the important load 30 is still connected to the commercial power system 10 via the first open/close switch 4 .

On the other hand, when a short-circuit accident (for example, a three-phase short circuit) occurs on the commercial power system 10 side, the voltage on the commercial power system 10 side drops. This voltage drop is detected by the grid-side voltage detector 6 . When the detected voltage detected by the grid-side voltage detector 6 is equal to or lower than the set value, the first controller 7 opens the first open/close switch 4 as shown in FIG. Then, as the uninterruptible power supply 1 starts self-sustaining operation, the heat utilization equipment 21 a as the distributed power supply 2 starts to operate, and these are interconnected to supply power to the important load 30 .

When the first open/close switch 4 is opened, as shown in FIG. 6, the heat utilization equipment 21a as the distributed power supply 2 is disconnected from the commercial power system 10. At this time, the heat utilization equipment 21a is used as an emergency power generator. Driving and not subject to FRT requirements.

Due to such operation of the power supply system 100, even when the voltage on the commercial power system 10 side becomes equal to or less than the set value and the first opening/closing switch 4 is opened, the second opening/closing switch 8 is opened, so the dispersion Unnecessary current can be prevented from flowing from the power supply 2 to the general load 40. - 特許庁

According to the power supply stem 100 of this embodiment configured as described above, the impedance element 5 is connected in parallel to the first open/close switch 4, and when the voltage on the commercial power system 10 side becomes equal to or lower than the set value, the first Since the on-off switch 4 is opened, the distributed power supply 2 is connected to the commercial power system 10 through the impedance element 5 even during the voltage drop. As a result, when the distributed power supply 2 is used as a regular power generator, the FRT requirements can be satisfied while exhibiting the load leveling function.
On the other hand, when the distributed power supply 2 is used as an emergency power generator, the first opening/closing switch 4 is connected in parallel and the second opening/closing switch 8 connected in series with the impedance element 5 is opened. Even if the opening/closing switch 4 is opened, it is possible to prevent current from flowing from the distributed power supply 2 to the general load 40 .
As a result, the distributed power source 2 can be used as a regular power generator or as an emergency power generator as needed.

<Modified Example of First Embodiment>
The present invention is not limited to the first embodiment.
For example, in the first embodiment, the second open/close switch 8 was provided closer to the commercial power system 10 than the impedance element 5 on the second power line L2, but as shown in FIG. It may be provided closer to the important load 30 than the impedance element 5 is.

Further, the second opening/closing switch 8 does not necessarily have to be a mechanical switch, and may be an opening/closing switch capable of high-speed switching such as a semiconductor switch or a hybrid switch combining a semiconductor switch and a mechanical switch. good. For example, even if a semiconductor switch using a semiconductor element having no self-extinguishing ability such as a thyristor is connected in parallel and used, it can be opened in a timely timing in a state where no current is flowing before the momentary sag occurs. Therefore, there is no need to provide a forced arc-extinguishing function, and the switch can be constructed at a relatively low cost.

Furthermore, as the impedance element 5, any one of a reactor, a resistor, and a capacitor may be used, or a combination of a plurality of these elements may be used.

<Second embodiment>
Next, a power supply system according to a second embodiment of the present invention will be described with reference to the drawings.
In the second embodiment, as shown in FIG. 8, the uninterruptible power supply 2b is capable of operation including reverse power flow with respect to the commercial power system 10, and the uninterruptible power supply 2b is used as a distributed power supply. 2 is different from the first embodiment.

That is, the power supply system 100 of the present embodiment includes a plurality of distributed power sources 2 that continue operation including reverse power flow to the commercial power system 10 when the commercial power system 10 is in a healthy state.

In this configuration, the second control unit 9 closes the second open/close switch 8 when at least one of the plurality of distributed power sources 2 is in operation, and closes the second open/close switch 8 when all of the plurality of distributed power sources 2 are stopped. If there is, the second open/close switch 8 is opened. That is, the second control unit 9 in this case obtains the state signals indicating whether each distributed power source 2 is in the operating state or in the stopped state, and controls the second opening/closing switch based on those state signals. 8 is controlled.

With such a configuration, when even one distributed power source 2 is in operation, the FRT requirements imposed on the distributed power source 2 can be satisfied while exhibiting the load leveling function of the distributed power source 2. .
On the other hand, when all of the distributed power sources 2 are in a stopped state, the second open/close switch 8 is opened. can prevent excessive current from flowing.

<Third Embodiment>
Next, a power supply system according to a third embodiment of the present invention will be described with reference to FIGS. 9 to 11. FIG.
The power supply system 100 of the third embodiment satisfies the FRT requirements for frequency fluctuation in addition to the FRT requirements for voltage drop in the first embodiment.

Specifically, as shown in FIG. 9, the power supply system 100 of the present embodiment detects frequency fluctuations on the side of the commercial power system 10 rather than the first open/close switch 4, in addition to the configuration of the first embodiment. A frequency variation detector 61 is provided. The frequency variation detector 61 detects frequency variation (frequency increase (OF), frequency decrease (UF)) from the voltage detected by the system side voltage detector 6 .

Then, the first control section 7 controls opening and closing of the first opening/closing switch 4 based on the frequency fluctuation detected by the frequency fluctuation detecting section 61 . Note that this frequency variation is, for example, step-up or ramp-up/down.

The specific opening/closing control of the first opening/closing switch 4 by the first control unit 7 and the operation of the distributed power supply 2 will be described with reference to FIGS. 10 and 11. FIG.

(1) When the frequency tolerance of the distributed power supply 2 and the important load 30 satisfies the frequency range (predetermined settling range) of the FRT requirements, and the frequency fluctuation of the commercial power system 10 is within the frequency range of the FRT requirements ((1) in FIG. 10), the first control unit 7 maintains the state in which the first open/close switch 4 is turned on. At this time, the distributed power supply 2 is continuously operated following the frequency fluctuation of the commercial power system 10 ((a) in FIG. 11).

(2) When the frequency tolerance of at least one of the distributed power supply 2 or the important load 30 does not satisfy the frequency range of the FRT requirements, and the frequency fluctuation of the commercial power system 10 is smaller than the frequency tolerance of the smaller one (Fig. 10 (2)), the first control unit 7 maintains the state in which the first open/close switch 4 is turned on. At this time, the distributed power supply 2 is continuously operated following the frequency fluctuation of the commercial power system 10 ((a) in FIG. 11).

(3) When the frequency tolerance of at least one of the distributed power supply 2 or the important load 30 does not satisfy the frequency range of the FRT requirements, and the frequency fluctuation of the commercial power system 10 is equal to or higher than the frequency tolerance of the smaller one and the FRT requirements ((3) in FIG. 10), the first controller 7 opens the first open/close switch 4 . Then, the distributed power supply 2 and the important load 30 are connected to the commercial power system 10 via the reactor 5 . At this time, if the operation is continued with the voltage of the distributed power supply 2 below the limit frequency, the frequency and phase will differ from the system side voltage. On the other hand, the reactor 5 suppresses the cross current due to the potential difference and the voltage fluctuation accompanying it, and it is possible to stabilize the power supply to the important load 30 while maintaining the voltage on the important load side at the limit frequency (Fig. 11). (b)).

Note that the frequency fluctuation detection unit 61 detects the frequency fluctuation of the commercial power system 10 regardless of whether the first open/close switch 4 is opened or closed, and the first control unit 7 detects the frequency fluctuation of the commercial power system 10 as described above. When the frequency becomes less than one frequency tolerance, the first open/close switch 4 is closed.

According to the power supply system 100 of this embodiment configured in this manner, in addition to the effects of the first embodiment, it is possible to prevent the dropout of important loads while satisfying the FRT requirements of the distributed power supply against frequency fluctuations. .

In addition, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications are possible without departing from the spirit of the present invention.

100... Power supply system 10... Commercial power system 30... Important load 40... General load L1... Power line L2... Second power line 1... Uninterruptible power supply 2... Distribution Type power supply 3 ... Parallel switch 4 ... First open/close switch 5 ... Impedance element 6 ... System side voltage detector 7 ... First controller 8 ... Second open/close switch 9 . . 2nd control section

Claims (5)

a distributed power source connected to the commercial power grid;
a first open/close switch provided on a power line connecting the commercial power system and the distributed power supply;
an impedance element connected in parallel to the first open/close switch;
a grid-side voltage detection unit that detects a voltage on the commercial power grid side of the first open/close switch;
opening the first open/close switch when the voltage detected by the grid-side voltage detection unit becomes equal to or less than a predetermined set value, and connecting the distributed power source and the commercial power grid via the impedance element; A power supply system comprising a first control unit,
a second opening/closing switch connected in parallel to the first opening/closing switch and connected in series to the impedance element;
obtaining a state signal indicating whether the distributed power source is in an operating state or a stopped state, and closing the second opening/ closing switch when the distributed power source is used as a regular power generator; and a second control section for opening the second opening/closing switch when the power supply is provided as an emergency power generator . 2. The power supply system according to claim 1, wherein when said state signal indicates said stopped state, said second control unit opens said second opening/closing switch in a state in which no current is flowing through said second opening/closing switch. 3. The power system according to claim 1, wherein said second opening/closing switch is a mechanical switch. The second control unit outputs an ON/OFF signal input to the distributed power source to switch the distributed power source to the operating state or the stopped state, and an ON/OFF signal output from the distributed power source to switch the distributed power source to the above One or more of an operating signal indicating whether the distributed power supply is in an operating state or the stopped state, or a time elapsed signal output from a timer for switching the operating state or the stopped state of the distributed power supply is acquired as the state signal. 4. The power supply system according to any one of claims 1 to 3, wherein The distributed power supply is a heat utilization facility that uses fuel to generate electricity and utilizes the exhaust heat, or an uninterruptible power supply that can operate including reverse power flow to the commercial power system. 5. The power supply system according to any one of 1 to 4.

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