JP2020162322A - Electrical power system - Google Patents

Abstract

To satisfy an FRT requirement when a dispersion type power source is used as a normal power generator, and suppress the generation of an unnecessary current at momentary power failure when the dispersion type power source is used as an emergency power generator.SOLUTION: An electrical power system 100, in which an impedance element 5 is connected in parallel to a first opening/closing switch 4 provided to a power line L1 for connecting a commercial power system 10 and a dispersion type power source 2, comprises: a second opening/closing switch 8 which is connected in serial to a parallel circuit having the first opening/closing switch 4 and the impedance element 5; and a second control part 9 which acquires a state signal indicating whether the dispersion type power source 2 is in an operation state or a stopping state, and closes the second opening/closing switch 8 when the state signal indicates the operation state, and opens the second opening/closing switch 8 when the state signal indicates the stopping state.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply system.

As a conventional power supply system, as shown in Patent Document 1, a function as a non-disruptive power supply system that supplies power to an important load in the event of an abnormality in the commercial power system (non-disruptive power supply function) and the order with respect to the commercial power system Some are configured to use a common distributed power source to achieve both a function as a distributed power source system (load leveling function) that leveles the load by flowing a tidal current and a reverse tide.

This power supply system connects the commercial power system and the distributed power supply in order to satisfy the so-called FRT (continuation of operation in the event of an accident) requirement that the distributed power supply is continuously operated without disconnecting from the commercial power system at a momentary low. An open / close switch is provided on the power line, and an impedance element is connected in parallel to the open / close switch.

With this configuration, even if the open / close switch is opened at the time of instantaneous low, the distributed power supply is connected to the commercial power system via the impedance element. It is possible to achieve both load leveling functions.

By the way, when the peak cut / peak shift effect of the distributed power source is reduced, for example, the fuel cost of the distributed power source is increased, the use of the distributed power source as a regular generator may not be economically viable. ..

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

However, as described above, when the impedance elements are connected in parallel to the open / close switch, as shown in FIG. 12, although the distributed power source as an emergency generator is not subject to FRT requirements. When the open / close switch is opened during a momentary low, the distributed power source and the commercial power system are connected via an impedance element. Then, an unnecessary current flows from the distributed power source to a load different from the important load connected to the commercial power system, which causes loss and heat.

Japanese Patent No. 6338131

Therefore, the present invention has been made to solve the above problems, and when the distributed power source is used as a regular generator, the distributed power source is used as an emergency generator while satisfying the FRT requirement. The main task is to be able to suppress the generation of unnecessary current at the time of instantaneous low.

That is, the 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, and the first open / close switch. The impedance elements connected in parallel, the system side voltage detection unit that detects the voltage on the commercial power system side of the first open / close switch, and the detection voltage of the system side voltage detection unit are equal to or less than a predetermined set value. This is a power supply system including a first control unit that opens the first open / close switch and connects the distributed power supply and the commercial power system via the impedance element.
Then, this power supply system indicates whether the first open / close switch, the second open / close switch connected in series to the parallel circuit having the impedance element, and the distributed power source are in the operating state or the stopped state. A second control that acquires a state signal and closes the second open / close switch when the state signal indicates the operating state, and opens the second open / close switch when the state signal indicates the stopped state. It is characterized by further including a part.

In such a power supply system, an impedance element is connected in parallel to the first open / close switch, and when the voltage on the commercial power system side falls below the set value, the second open / close switch is closed. 1 Since the open / close switch is opened, the distributed power source is in a state of being connected to the commercial power system via the impedance element even at a momentary low voltage. As a result, it is possible to satisfy the FRT requirement while exerting the load leveling function by using the distributed power source as a regular generator.
Moreover, since the second open / close switch is connected in series to the first open / close switch and the parallel circuit having the impedance element, when the distributed power source is in the operating state as a regular generator, this second open / close switch is used. The first open / close switch and the second open / close switch when the distributed power source is stopped, that is, when the distributed power source is provided as an emergency generator while closing and satisfying the FRT requirement as described above. By opening the switch, it is possible to prevent the generation of unnecessary current at the time of instantaneous low.

When the state signal indicates the stopped state, it is preferable that the second control unit opens the second open switch in synchronization with the opening of the first open / close switch by the first control unit.
When a distributed power source is used as an emergency generator, the opening of the first open / close switch and the second open / close switch at the time of a momentary low are synchronized, so that unnecessary current is generated more reliably at the time of a momentary low. Can be suppressed to.

As an embodiment for synchronizing the opening of the first open / close switch and the opening of the second open / close switch, the second open / close switch may be a semiconductor switch, or a hybrid switch in which a semiconductor switch and a mechanical switch are combined. Can be mentioned.

As a specific embodiment for automating the control of the second open / close switch, the second control unit is input to the distributed power source to switch the distributed power source to the operating state or the stopped state. / OFF signal, an operation signal output from the distributed power source indicating whether the distributed power source is in the operating state or the stopped state, or for switching the operating state or stopped state of the distributed power source. An embodiment of acquiring one or more of the time elapsed signals output from the timer of the above as the state signal can be mentioned.

As a specific embodiment of the distributed power supply, a heat utilization facility that generates electricity using fuel and uses the exhaust heat thereof, or an uninterruptible power supply that can be operated including reverse power flow to the commercial power system. Equipment is mentioned.

According to the present invention configured in this way, when the distributed power source is used as a regular generator, the FRT requirement is satisfied, and when the distributed power source is used as an emergency generator, it is in a momentary low state. It is possible to suppress the generation of unnecessary current.

It is a schematic diagram which shows the structure of the power supply system of 1st Embodiment. It is a schematic diagram which shows the state of the power-source system in the normal state which the distributed power source of 1st Embodiment is in an operating state. It is a schematic diagram which shows the state of the power-source system at the time of momentary low when the distributed power source of 1st Embodiment is in an operating state. It is a schematic diagram which shows the operation of the power-source system when the distributed power source of 1st Embodiment is a stop state. It is a schematic diagram which shows the state of the power-source system at the time of the normal time when the distributed power source of 1st Embodiment is a stop state. It is a schematic diagram which shows the state of the power-source system at the time of momentary low when the distributed power source of 1st Embodiment is stopped state. It is a schematic diagram which shows the structure of the power-source 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 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. It is a schematic diagram for demonstrating the unnecessary current flowing in a conventional structure.

<First Embodiment>
The first embodiment of the 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 critical load 30, and is an uninterruptible power supply system that supplies power to the critical load 30 when the commercial power system 10 is abnormal. (Uninterruptible power supply function) and the function as a distributed power supply system (load leveling function) that equalizes the load by flowing forward and reverse power to the commercial power system 10.

Here, the commercial power system 10 is a power supply network of an electric power company (electric power company), and has a power plant, a power transmission system, and a power distribution system. Further, the important load 30 is a load that should stably supply electric power even in the event of a system abnormality such as a power failure or a momentary low, and although it is one in FIG. 1, it may be a plurality. Further, one or more general loads 40 other than the important load 30 are also connected to the trademark power system 10.

Specifically, the power supply system 100 includes an uninterruptible power supply (UPS) 1, a distributed power supply 2, a disconnection switch 3 for disconnecting the commercial power system 10 and the distributed power supply 2, and a commercial power system. The first open / close switch 4 that connects and disconnects the 10 from the distributed power supply 2 and the critical load 30, the impedance element 5 connected in parallel to the first open / close switch 4, and the commercial power system 10 side of the first open / close switch 4. It includes a system-side voltage detection unit 6 that detects a voltage, and a first control unit 7 that opens the first open / close switch 4 when the detection voltage of the system-side voltage detection unit 6 becomes equal to or less than a set value.

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

The distributed power source 2 is connected to a power line L1 for supplying power from the commercial power system 10 to the critical load 30. The distributed power source 2 is connected to the commercial power system 10, and is called, for example, a so-called cogeneration or monogene, which is a heat utilization facility 21a using fuel. The heat utilization facility 21a uses gas, petroleum, or the like as fuel to generate electricity by an engine, a turbine, a fuel cell, or the like, and utilizes the exhaust heat thereof. In addition, the distributed power source 2 includes DC power generation equipment such as solar power generation and fuel cells and a power conversion device (not shown), and DC electric energy output by AC such as wind power generation and micro gas turbine. Power generation equipment (not shown) that is grid-connected using a power converter after rectifying to the above, or AC power generation equipment (not shown) such as a synchronous generator or an induction generator can be mentioned. One or more of these may be provided.

The disconnection switch 3 is, for example, a mechanical switch provided on the commercial power system 10 side of the connection point of the distributed power source 2 on the power line L1. The disconnection switch 3 is opened / closed controlled by a first control unit 7 described later, and is opened when a predetermined disconnection condition is satisfied.

The first open / close switch 4 opens and closes the power line L1, and an open / close switch capable of high-speed switching such as a semiconductor switch or a hybrid switch in which a semiconductor switch and a mechanical switch are combined can be used. For example, when a semiconductor switch is used, the switching time can be set to 2 ms or less, and the switch can be shut off regardless of the zero point. Further, when a hybrid switch is used, the switching time can be set to 2 msec or less, and not only can the switch be cut off regardless of the zero point, but also the energization loss can be set to zero. The first open / close switch 4 is controlled to open / close by the first control unit 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 the present embodiment. The parallel circuit including the first open / close switch 4 and the impedance element 5 is provided on the important load 30 side of 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 first open / close switch 4 on the power line L1 via the voltage transformer for the instrument. Specifically, the system-side voltage detection unit 6 is connected to the commercial power system 10 side via a voltage transformer rather than the parallel circuit including the first open / close switch 4 and the impedance element 5.

The first control unit 7 compares the detected voltage detected by the system side voltage detection unit 6 with a predetermined set value, and when the detected voltage is equal to or less than the set value, the first open / close switch 4 A control signal is output to the switch 4 to open the first open / close switch 4. The set value of the present embodiment is a voltage value for detecting a momentary drop. When the first control unit 7 opens the first open / close switch 4 in this way, the commercial power system 10, the distributed power source 2, and the important load 30 are connected to each other via the impedance element 5. In this state, the distributed power source 2 continues the operation including the reverse power flow.

In this way, when the distributed power source 2 operates including reverse power flow, peak cut / peak shift can be realized by the distributed power source 2, and therefore, the load is loaded by using this distributed power source 2 as a regular generator. The leveling function is demonstrated.
However, for example, when the fuel cost used for the heat utilization facility 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 source 2 of the present embodiment is kept connected to the commercial power system 10 and kept in a stopped state to be used as an emergency generator.

However, in the above-described configuration, the power supply system 100 of the present embodiment has a second open / close switch 8 connected in series to a parallel circuit including the first open / close switch 4 and the impedance element 5, and the second open / close switch 8. A second control unit 9 for controlling the above is provided.

The second open / close switch 8 is provided on the power line L1 to open / close the first power line L1. In this embodiment, the second open / close switch 8 is provided on the commercial power system 10 side of the parallel circuit described above in the power line L1, and is, for example, a semiconductor switch or a hybrid in which a semiconductor switch and a mechanical switch are combined. It is an open / close switch that can be switched at high speed such as a switch.

The second control unit 9 acquires a state signal indicating whether the distributed power source 2 is in the operating state or the stopped state, and closes the second open / close switch 8 when the state signal indicates the operating state. .. On the other hand, when the status signal indicates a stopped state, the second open / close switch 8 is opened / closed in synchronization with the opening / closing of the first open / close switch 4. That is, when the state signal indicates a stopped state and the first control unit 7 closes the first open / close switch 4, the second control unit 9 closes the second open / close switch 8 and the state signal stops. When the state is indicated and the first control unit 7 opens the first open / close switch 4, the second control unit 9 opens the second open / close switch 8.
Here, when the distributed power source 2 is in the operating state, the distributed power source 2 is used as a regular generator that continues the operation including the reverse power flow. On the other hand, when the distributed power source 2 is in the stopped state, the distributed power source 2 is provided as an emergency generator. That is, the second control unit 9 closes the second open / close switch 8 when the distributed power source 2 is used as a regular generator, and when the distributed power source 2 is provided as an emergency generator. Opens the second open / close switch 8 in synchronization with the opening of the first open / close switch 4.
The second control unit 9 may be a function exerted by a CPU common to the first control unit 7, or may be a function exerted by a CPU different from the first control unit 7. ..

The second control unit 9 of the present embodiment acquires an operation signal output from the distributed power source 2 and indicating whether the distributed power source 2 is in the operating state or the stopped state as the above-mentioned state signal. It is configured to determine whether the distributed power source 2 is in an operating state or 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 the operating state or the stopped state may be acquired as a state signal. Further, when the distributed power source 2 is switched between an operating state and a stopped state according to, for example, a time zone, the second control unit 9 is output from a timer for switching the operating state or the stopped state of the distributed power source 2. The time elapsed signal may be acquired as a state signal.

Next, regarding the operation of the power supply system 100 of the present embodiment (normal time and instantaneous low time), the case where the distributed power source 2 which is the heat utilization facility 21a is used as a regular generator and the case where it is used as an emergency generator are divided. , FIGS. 2 to 6 will be described.

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

In the state where the second open / close switch 8 is closed in this way, the power supply system 100 normally closes the first open / close switch 4, as shown in FIG. 2, with the distributed power supply 2 and the important load 30. Is in 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, so that the commercial power system 10, the distributed power source 2, and the important load 30 are used. Exchanges power on the first open / close switch 4 side. In this state, peak cut and peak shift can be realized by reverse power flow by the distributed power source 2.

On the other hand, if 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 system side voltage detection unit 6. The first control unit 7 opens the first open / close switch 4 when the detection voltage detected by the system side voltage detection unit 6 is equal to or less than the set value. Then, the uninterruptible power supply 1 starts an independent operation to supply power to the critical load 30.

As shown in FIG. 3, when the first open / close switch 4 is opened, the second open / close switch 8 is closed, so that the distributed power source 2 and the critical load 30 are connected to the commercial power system 10 via the reactor 5. It becomes a state. In this state, the current flowing from the distributed power source 2 to the short-circuit fault point is limited by the reactor 5, the fault current flowing to the short-circuit fault point is suppressed, and the voltage drop of the critical load 30 is prevented. Further, in this state, the distributed power source 2 continues the operation including the reverse power flow, and continues the power generation output.

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

The system side voltage detection unit 6 detects the voltage on the commercial power system 10 side regardless of the opening / closing of the first open / close switch 4, and the first control unit 7 detects the detection voltage of the system side voltage detection unit 6. Is equal to or higher than a predetermined return voltage, for example, when the residual voltage of the commercial power system is 80% or higher, the first open / close switch 4 is closed.

Due to such an operation of the power supply system 100, the voltage on the commercial power system 10 side becomes equal to or less 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 commercialized via the reactor 5. It will be connected to the power system 10. Therefore, the distributed power source 2 and the critical load 30 are not separated from the commercial power system 10 in either the normal state or the instantaneous voltage drop. Therefore, when the distributed power source 2 is used as a regular generator, this distributed type is used. While satisfying the FRT requirement imposed on the power source 2, it is possible to prevent a voltage drop to the critical load 30 at a momentary low. As a result, both the uninterruptible power supply function and the load leveling function can be achieved at the same time.

[When the distributed power source 2 is used as an emergency generator]
On the other hand, when the distributed power source 2 is used as an emergency generator, as shown in FIG. 4, the above-mentioned second control unit 9 determines that the distributed power source 2 is in the stopped state, and determines that the distributed power source 2 is in the stopped state, and the first open / close switch. The second open / close switch 8 is opened / closed in synchronization with the opening / closing of 4.

Specifically, the power supply system 100 normally closes the first open / close switch 4 and the second open / close switch 8 as shown in FIG. 5, and uses heat as an uninterruptible power supply 1 and an emergency generator. Equipment 21a is provided for emergencies while being connected to the commercial power system 10. Of course, the important load 30 is in a state of being connected to the commercial power system 10 via the first open / close switch 4.

On the other hand, if 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 system side voltage detection unit 6. When the detection voltage detected by the system side voltage detection unit 6 is equal to or less than the set value, the first control unit 7 opens the first open / close switch 4 and synchronizes with the opening, as shown in FIG. Then, the second control unit 9 opens the second open / close switch 8. Then, the uninterruptible power supply 1 starts the self-sustaining operation, and the heat utilization equipment 21a, which is the distributed power supply 2, starts to start, and these are interconnected to supply power to the important load 30.

When the first open / close switch 4 and the second open / close switch 8 are opened, as shown in FIG. 6, the heat utilization facility 21a as the distributed power source 2 is disconnected from the commercial power system 10, and the heat utilization facility 21a at this time is disconnected. Is operating as an emergency generator and is not subject to FRT requirements.

Due to such an operation of the power supply system 100, the voltage on the commercial power system 10 side becomes equal to or lower than the set value, and when the first open / close switch 4 is opened, the second open / close switch 8 is opened in synchronization with this opening. It is possible to prevent unnecessary current from flowing from the distributed power source 2 to the general load 40.
Note that the synchronization referred to here does not necessarily mean that the opening of the first open / close switch 4 and the opening of the second open / close switch 8 do not necessarily occur at the same time, and the effect of reducing the unnecessary current flowing from the distributed power source 2 to the general load is achieved. There may be a slight time difference as long as it is obtained.

According to the power supply stem 100 of the present embodiment configured in this way, when the impedance element 5 is connected in parallel to the first open / close switch 4 and the voltage on the commercial power system 10 side becomes equal to or less than the set value, the first switch 2 Since the first open / close switch 4 is opened in the state where the open / close switch 8 is closed, the distributed power source 2 is connected to the commercial power system 10 via the impedance element 5 even at a momentary voltage drop. As a result, when the distributed power source 2 is used as a regular generator, the FRT requirement can be satisfied while exerting the load leveling function.
On the other hand, when the distributed power source 2 is used as an emergency generator, the second open / close switch 8 is connected in series to the parallel circuit including the first open / close switch 4 and the impedance element 5, so that the first open / close switch 8 is connected to the parallel circuit including the impedance element 5. Since the open / close switch 4 is opened and the second open / close switch 8 is opened in synchronization with the opening / closing switch 4, it is possible to prevent the current from flowing from the distributed power source 2 to the general load 40.
As a result, the distributed power source 2 can be used as both a regular generator and an emergency generator, if necessary.

<Modified example of the first embodiment>
The present invention is not limited to the first embodiment.
For example, in the first embodiment, the second open / close switch 8 is provided on the commercial power system 10 side of the first power line L1 with respect to the parallel circuit having the first open / close switch 4 and the impedance element 5. As shown in FIG. 7, it may be provided on the important load 30 side of the parallel circuit on the first power line L1.

Further, when the distributed power source 2 is in the stopped state and is provided as an emergency generator, in the above-described embodiment, the first open / close switch 4 is opened at the time of a momentary low, and the second open / close switch 4 is opened in synchronization with the opening. Although the open / close switch 8 has been opened, the second open / close switch 8 may be opened without opening the first open / close switch 4.
Even in this way, the distributed power source 2 is provided as an emergency generator, and it is possible to prevent the current from flowing from the distributed power source 2 to the general load 40 at a momentary low in a state where the FRT requirement is not imposed. Can be done.

Further, as the impedance element 5, any of a reactor, a resistor, and a capacitor may be used, or a plurality of these may be combined.

<Second Embodiment>
Next, a second embodiment of the power supply system according to 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 can be operated with respect to the commercial power system 10 including reverse power flow, and the uninterruptible power supply 2b is a distributed power source. It differs from the first embodiment in that it is used as 2.

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 with respect to the commercial power system 10 in a healthy state of the commercial power system 10.

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 the operating state, and all of the plurality of distributed power sources 2 are stopped. If there is, the second open / close switch 8 is opened / closed in synchronization with the opening / closing of the first open switch 4. That is, the second control unit 9 in this case acquires status signals indicating whether each distributed power source 2 is in the operating state or the stopped state, and the second open / close switch is based on the status signals. 8 is controlled.

With this configuration, when even one distributed power source 2 is in an operating state, the FRT requirement imposed on the distributed power source 2 can be satisfied while exerting the load leveling function of the distributed power source 2. ..
On the other hand, when all the distributed power sources 2 are in the stopped state, the second open / close switch 8 is opened in synchronization with the opening of the first open switch 4 at the moment of low voltage, so that each distributed power source 2 is changed to the general load 40. It is possible to prevent unnecessary current from flowing.

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

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

Then, the first control unit 7 controls the opening / closing of the first open / close switch 4 based on the frequency fluctuation detected by the frequency fluctuation detection unit 61. It should be noted that this frequency fluctuation is, for example, a step rise or a ramp rise / fall.

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

(1) When the frequency withstands of the distributed power source 2 and the critical load 30 satisfy the frequency range of the FRT requirement (predetermined setting range), and the frequency fluctuation of the commercial power system 10 is within the frequency range of the FRT requirement. ((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 source 2 is continuously operated following the frequency fluctuation of the commercial power system 10 ((a) in FIG. 11).

(2) When the frequency withstand of at least one of the distributed power source 2 or the critical load 30 does not satisfy the frequency range of the FRT requirement, and the frequency fluctuation of the commercial power system 10 is smaller than the frequency withstand 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 source is continuously operated following the frequency fluctuation of the commercial power system ((a) in FIG. 11).

(3) When the frequency withstand of at least one of the distributed power source 2 or the critical load 30 does not satisfy the frequency range of the FRT requirement, the frequency fluctuation of the commercial power system 10 is equal to or greater than the frequency withstand of the smaller one, and the FRT requirement. When the frequency is within the frequency range of ((3) in FIG. 10), the first control unit 7 opens the first open / close switch 4. Then, the distributed power source 2 and the critical load 30 are connected to the commercial power system 10 via the reactor 5. At this time, if the operation of the distributed power source 2 is continued below the limit frequency, the frequency and phase will be different 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 can stabilize the power supply to the critical load 30 while maintaining the voltage on the critical load side at the limit frequency (FIG. 11). (B)).

The frequency fluctuation detection unit 61 detects the frequency fluctuation of the commercial power system 10 regardless of the opening / closing of the first open / close switch 4, and the first control unit 7 has the small frequency fluctuation of the commercial power system 10. When the frequency capacity of the other side becomes less than the withstand frequency, the first open / close switch 4 is closed.

According to the power supply system 100 of the present embodiment configured in this way, in addition to the effect of the first embodiment, it is possible to prevent the important load from falling off while satisfying the FRT requirement of the distributed power source against frequency fluctuation. ..

In addition, the present invention is not limited to each of the above-described embodiments, and it goes without saying that various modifications can be made 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 ・ ・ ・ Distributed Type power supply 3 ・ ・ ・ Disengagement switch 4 ・ ・ ・ First open / close switch 5 ・ ・ ・ Impedance element 6 ・ ・ ・ System side voltage detection unit 7 ・ ・ ・ 1st control unit 8 ・ ・ ・ 2nd open / close switch 9 ・・ ・ 2nd control unit

Claims (5)

With a distributed power source connected to the commercial power system,
A first open / close switch provided on a power line connecting the commercial power system and the distributed power source,
An impedance element connected in parallel to the first open / close switch and
A system-side voltage detection unit that detects the voltage on the commercial power system side of the first open / close switch, and
When the detection voltage of the system side voltage detection unit becomes equal to or less than a predetermined set value, the first open / close switch is opened, and the distributed power source and the commercial power system are connected via the impedance element. A power supply system equipped with a first control unit.
The first open / close switch and the second open / close switch connected in series to the parallel circuit having the impedance element,
When a state signal indicating whether the distributed power source is in an operating state or a stopped state is acquired and the state signal indicates the operating state, the second open / close switch is closed and the state signal stops. A power supply system further including a second control unit that opens the second open / close switch when indicating a state. The first aspect of the present invention, wherein when the state signal indicates the stopped state, the second control unit opens the second release switch in synchronization with the opening of the first open / close switch by the first control unit. Power system. The power supply system according to claim 1 or 2, wherein the second open / close switch is a semiconductor switch or a hybrid switch in which a semiconductor switch and a mechanical switch are combined. The second control unit is input to the distributed power source, an ON / OFF signal for switching the distributed power source to the operating state or the stopped state, is output from the distributed power source, and the distributed power source is said. Acquire one or more of the operation signal indicating whether the distributed power source is in the operating state or the stopped state, or one or a plurality of time elapsed signals output from the timer for switching the operating state or the stopped state of the distributed power source as the state signal. The power supply system according to any one of claims 1 to 3. The distributed power supply is a heat utilization facility that uses fuel to generate electricity and uses the exhaust heat, or an uninterruptible power supply that can operate including reverse power flow to the commercial power system. The power supply system according to any one of 1 to 4.