JP6234125B2 - Load change device - Google Patents

Load change device Download PDF

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JP6234125B2
JP6234125B2 JP2013186899A JP2013186899A JP6234125B2 JP 6234125 B2 JP6234125 B2 JP 6234125B2 JP 2013186899 A JP2013186899 A JP 2013186899A JP 2013186899 A JP2013186899 A JP 2013186899A JP 6234125 B2 JP6234125 B2 JP 6234125B2
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load
switchgear
phase
switch
power supply
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JP2015056906A (en
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怜 永安
怜 永安
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三菱電機株式会社
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/50Arrangements for eliminating or reducing asymmetry in polyphase networks

Description

  The present invention relates to a load changing device for improving an unbalanced state in a three-phase AC circuit.

  Conventionally, the three-phase AC circuit is in an unbalanced state, causing an event that hinders the use of electrical equipment. For example, in a three-phase induction motor, when the three-phase AC circuit is in an unbalanced state, various phenomena such as an increase in temperature, a decrease in efficiency, and an increase in vibration and noise are caused. For this reason, many facilities have established management standards for the unbalanced state of the three-phase AC circuit, and improving the unbalanced state of the three-phase AC circuit is also necessary for the stable supply of power and the life extension of the equipment. For example, there has been proposed an unbalanced load correction device in which a dummy load is connected to a phase having a low load in order to improve an unbalanced state. (For example, Patent Document 1)

Japanese Patent Publication No.59-3103

  In order to improve the unbalanced state of the three-phase AC circuit, the conventional unbalanced load correction device makes the load of each phase uniform by adding a load (dummy load) to the low-load phase. ing. However, the adjustment load (dummy load) necessary to improve the unbalanced state is large. For example, equipment class equipment such as water resistance and large-capacity resistance must be prepared, and power consumption is high. In order to add a load (dummy load) according to the situation, there is a problem that it leads to an increase in loss energy.

  The present invention was made to solve the above problems, and it is not necessary to prepare equipment class equipment such as water resistance and large-capacity resistance as a load for adjustment, and load change that does not cause loss energy An object is to provide an apparatus.

The load changing device according to the present invention is a load changing device that changes power to be supplied from a second phase to a load that is supplied from a first phase in a three-phase AC circuit, the load changing device And supplying power from between the first phase via the first switchgear and connecting the second switchgear in an open state from between the second phase, the first switchgear, A first parallel connection body of the first on-off switch and the first bidirectional switching element, and a first ammeter provided on the load side of the first parallel connection body, The switchgear sandwiches the second parallel connection body with the second parallel connection body of the second open / close switch, the second bidirectional switching element, and the third bidirectional switching element in which the resistors are connected in series. And a first voltmeter provided on the power source side, A second voltmeter and a second ammeter provided on the load side, and the timing of opening the first switchgear according to the values of the first ammeter and the second ammeter And a control means for controlling the power supply to the load to be switched from the first phase to the second phase without causing a short circuit between the second phases by determining a timing for closing the second switchgear, The switching control by the control means includes a procedure for turning on the third bidirectional switching element when the values of the first voltmeter and the second voltmeter become the same. It is what.

According to the load changing device of the present invention, power is supplied to the load from the first phase through the first switchgear and the second switchgear is also connected from the second phase in an open state. The first switchgear includes a first parallel connection body of a first open / close switch and a first bidirectional switching element, and a first ammeter provided on the load side of the first parallel connection body. A second parallel connection of the second switch and the second bidirectional switching element and a third bidirectional switching element in which a resistor is connected in series; A first voltmeter provided on the power supply side across the second parallel connection body, a second voltmeter provided on the load side, and a second ammeter. The first switchgear according to the values of the ammeter and the second ammeter Control means for controlling the power supply to the load to be switched from the first phase to the second phase without causing a short-circuit between the second phases by determining a timing for closing the second switchgear. The switching control by the control means includes a procedure for turning on the third bidirectional switching element when the values of the first voltmeter and the second voltmeter become the same . Since it can be controlled to switch the power supply to the load from the first phase to the second phase without causing a short circuit between the phases, there is no need to prepare a separate device for the adjustment load. There is an effect that it is possible to obtain a load changing device that does not generate loss energy.

It is a block diagram which shows schematic structure of the load change apparatus in Embodiment 1 of this invention. It is a circuit diagram which shows the 1st switchgear of the load change apparatus in Embodiment 1 of this invention. It is a circuit diagram which shows the 2nd switchgear of the load change apparatus in Embodiment 1 of this invention. It is explanatory drawing explaining the switching operation | movement of the load change apparatus in Embodiment 1 of this invention. It is explanatory drawing explaining the switching operation | movement detail of the load change apparatus in Embodiment 1 of this invention. It is a block diagram which shows schematic structure of the load change apparatus in Embodiment 2 of this invention. It is explanatory drawing explaining the switching operation | movement of the load change apparatus in Embodiment 2 of this invention. It is explanatory drawing explaining the switching operation failure of the load change apparatus in Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described. In the drawings, the same or corresponding parts will be described with the same reference numerals.
Embodiment 1 FIG.
1 is a block diagram showing a schematic configuration of a load changing device according to Embodiment 1 of the present invention, FIG. 2 is a circuit diagram showing a first switching device of the load changing device according to Embodiment 1 of the present invention, and FIG. 4 is a circuit diagram showing a second opening / closing device of the load change device according to Embodiment 1 of the present invention, FIG. 4 is an explanatory diagram for explaining the switching operation of the load change device according to Embodiment 1 of the present invention, and FIG. It is explanatory drawing explaining the switching operation | movement detail of the load change apparatus in this Embodiment 1. FIG.
In FIG. 1, power is supplied to a load (not shown) via an R-phase power source bus 2, an S-phase power source bus 3 and a T-phase power source bus 4 connected to a three-phase AC power source 1. Here, in order to explain the invention more easily, in the following description, as an example, the phase between the R-phase power supply bus 2 and the S-phase power supply bus 3 is set as the first phase and the load between the first phases is set as the first phase. Load between the S-phase power supply bus 3 and the T-phase power supply bus 4 as the second phase and the load between the second phase as the second load (not shown). Assume that the first load is in an unbalanced state greater than the second load.

  A first opening / closing device 5 described in detail later is connected between the first phases, and a second opening / closing device 6 described in detail later is connected between the second phases. 5 and the second switchgear 6 are connected by a secondary load bus 7 and a secondary load bus 8, and a load 9 for adjusting an unbalanced state is connected. The load 9 is proportionally distributed from the first load to a value smaller than the difference between the first load and the second load, and is half the difference between the first load and the second load. Ideally. In this state, the first opening / closing device 5 is closed, the second opening / closing device 6 is open, and the load 9 is supplied with power from the first phase via the first opening / closing device 5. The central controller 10 monitors the load status of the three-phase AC circuit. When the first load is in an unbalanced state larger than the second load, the first control device 5 and the first switch 5 are connected via the communication line 11. A change command signal is transmitted to the second switchgear 6. When the change command signal is received, the operation will be described in detail later. However, when the first switching device 5 is opened and the second switching device 6 is closed, the power supply to the load 9 is changed from the first phase to the second phase. Is changed to.

  Next, detailed structures of the first opening / closing device 5 and the second opening / closing device 6 will be described with reference to FIGS. The first opening / closing device 5 and the second opening / closing device 6 are devices having the same structure except that the connected power bus is different, and the structure will be described together. Circuits of bidirectional thyristors 52 and 62 that are bidirectional switching elements connected in parallel with the on-off switches 51 and 61 and bidirectional thyristors 54 and 64 that are bidirectional switching elements connected in series with the resistors 53 and 63 are further provided. The switches are connected in parallel to form a parallel triple configuration. Ammeters 55 and 65 for detecting the current flowing through the secondary load bus 8 are provided on the load side of the switch. Further, primary voltmeters 56 and 66 for detecting the voltage on the power supply side of the switch and secondary voltmeters 57 and 67 for detecting the voltage on the load side of the switch are provided. The currents detected by the ammeters 55 and 65 and the voltages detected by the primary side voltmeters 56 and 66 and the secondary side voltmeters 57 and 67 are given to the control devices 59 and 69 via signal lines 58, respectively. It is done. The control devices 59 and 69 receive the change command signal from the central control device 10 via the communication line 11, and open / close the open / close switches 51 and 61, the bidirectional thyristors 52 and 62, and the bidirectional thyristors 54 and 64 as signal lines. 58 and 68.

  First, the outline operation of the entire load changing device that omits the internal operation of the switchgear when the power supply path to the load 9 is switched will be described with reference to FIG. When the first switchgear 5 is closed and the second switchgear 6 is opened, that is, the power supply path to the load 9 is from the R-phase power source bus 2 and the S-phase power source bus 3 of the three-phase AC power source 1. It is assumed that the state is via the first switchgear 5 and the secondary load buses 7 and 8. In this state, by outputting a power supply path change command signal from the central controller 10 to the first switchgear 5 and the second switchgear 6 via the communication line 11, the first switchgear 5 Since the open second switchgear 6 is closed, the power supply path to the load 9 is for the second switchgear 6 and the secondary load from the S-phase power supply bus 3 and the T-phase power supply bus 4 of the three-phase AC power supply 1. It is switched to a state via buses 7 and 8. In order to return to the original state in this state, the first opening / closing device 5 and the second opening / closing device 6 have the same configuration, and therefore the first opening / closing device 5 and the second opening / closing device 5 from the central control device 10 via the communication line 11. Since the second switchgear 6 is opened and the first switchgear 5 is closed by outputting the power supply path change command to the switchgear 6 again, the power supply path to the load 9 is three-phase alternating current. The state returns from the R-phase power source bus 2 and the S-phase power source bus 3 of the power source 1 to the state via the first switching device 5 and the secondary load buses 7 and 8.

Next, detailed operations of the first opening / closing device 5 and the second opening / closing device 6 when the power supply path is changed will be described with reference to the time charts shown in FIGS. 4 and 5. Since the power supply bus connected to the first switchgear 5 and the second switchgear 6 is different, the (first) switchgear 51 of the first switchgear 5 and the second switchgear6 The (second) open / close switch 61 cannot be closed at the same time. However, since the power supply path change to the load 9 needs to be performed without a power failure so that the power supply is not interrupted, the switching operation is executed according to the following procedure.
In the state where the power supply path to the load 9 is via the first switchgear 5, only the (first) switch 51 of the first switchgear 5 is closed (ON), and the first switchgear 5 The (first) bidirectional thyristor 52 and the bidirectional thyristor 54 are in a non-conductive (OFF) state. Further, the (second) opening / closing switch 61, the (second) bidirectional thyristor 62, and the (third) bidirectional thyristor 64 of the second opening / closing device 6 are all open (OFF). In this state, when a change command signal is transmitted from the central control device 10 to the control device 59 of the first switching device 5 and the control device 69 of the second switching device 6 via the communication line 11, the control device 59. , 69 is executed to change the power supply path to the load 9, which will be described in detail below.

In FIG. 4, when the control device 59 of the first opening / closing device 5 receives the change command signal from the central control device 10 via the communication line 11, it gives a drive signal to the bidirectional thyristor 52 to provide the bidirectional thyristor 52. Is turned on (ON) and then an open command signal is given to the open / close switch 51 to open (OFF) the open / close switch 51, thereby changing the power supply to the load 9 from the open / close switch 51 to the bidirectional thyristor 52. . At this time, in order not to interrupt the power supply to the load 9, a time is provided in which the open / close switch 51 and the bidirectional thyristor 52 are simultaneously closed (ON). Waiting for the first switching device 5 to be in a power supply state via the bidirectional thyristor 52, the control device 69 of the second switching device 6 drives the bidirectional thyristor 64 connected in series with the resistor 63. The bidirectional thyristor 64 is closed (ON) in response to a signal. The timing for driving the bidirectional thyristor 64 is set so that the values detected by the primary voltmeter 66 and the secondary voltmeter 67 become equal as shown in FIG.

  Here, since the bidirectional thyristor 52 of the first switchgear 5 is closed (ON), the first switchgear 5 is in a state where the primary side and the secondary side are short-circuited. When the bidirectional thyristor 64 of the second switchgear 6 is turned on (ON), the primary side and the secondary side of the second switchgear 6 are connected by the resistor 63. That is, this state is a state in which the resistor 63 of the second switching device 6 is connected between the R-phase power source bus 2 and the T-phase power source bus 4 of the three-phase AC power source 1. Therefore, a current obtained by dividing the potential difference between the phases by the resistor 63 flows between the R-phase power supply bus 2 and the T-phase power supply bus 4, but the flowing current is as shown by the values of the ammeter 55 and the ammeter 65 shown in FIG. In addition, the resistance value of the resistor 63 is set so that the current is clearly larger than the current flowing to the load 9 before the bidirectional thyristor 64 is closed (ON).

  Next, the control device 59 of the first switching device 5 detects that the current value of the ammeter 55 has increased, and turns off the drive signal for the bidirectional thyristor 52. However, since the bidirectional thyristor 52 has thyristor characteristics. The current continues to flow until the current flowing through the bidirectional thyristor 52 becomes zero. Specifically, since the bidirectional thyristor 64 is closed (ON) at the timing when the values of the primary voltmeter 66 and the secondary voltmeter 67 become equal, the voltage waveform is about ½ after the bidirectional thyristor 64 is turned on. The current flowing through the bidirectional thyristor 52 becomes zero when the cycle elapses, and the bidirectional thyristor 52 is opened (OFF).

  On the other hand, the control device 69 of the second switching device 6 confirms the value of the ammeter 65 at the time when 3/4 period has elapsed in the voltage waveform from the timing when the bidirectional thyristor 64 is turned on. The value of the ammeter 65 at the timing when ¾ cycle has passed is sufficiently reduced with respect to the value of the ammeter 65 from the timing when the bidirectional thyristor 64 of the second switchgear 6 is turned on to ½ cycle. Then, it is determined that no current flows between the R-phase power supply bus 2 and the T-phase power supply bus 4 and the state of the first switchgear 5 is open. After determining that the state of the first opening / closing device 5 is open, the control device 69 of the second opening / closing device 6 gives a closing command signal to the opening / closing switch 61 and also to the bidirectional thyristor 62. Give drive signal. This is because the opening / closing switch 61 and the bidirectional thyristor 62 are closed (ON) with good timing by utilizing the fact that the operation speed of the bidirectional thyristor 62 is higher than the operation speed of the opening / closing switch 61. After securing a sufficient time for the opening / closing switch 61 to close, the control device 69 of the second opening / closing device 6 stops the drive signal applied to the bidirectional thyristor 62 and the bidirectional thyristor 64, and the bidirectional thyristor 62 and The bidirectional thyristor 64 is opened (OFF), and only the open / close switch 61 of the second switch 6 is closed (ON), and the power supply path to the load 9 is the second switch 6. It will be in a via state.

As described above, by changing the power supply path to the load 9, the unbalanced state of the three-phase AC circuit can be improved without using large-scale equipment such as water resistance or large-capacity resistance. Furthermore, since the load 9 is apportioned from the first load, a load changing device that hardly generates loss energy can be obtained.
However, in the operation process of changing the power supply path, power is supplied to the load 9 through the resistor 63 for about ¼ period from when the bidirectional thyristor 52 is opened until the bidirectional thyristor 62 is closed. 9, a voltage drop corresponding to the resistance ratio between the load 9 and the resistor 63 occurs. In addition, the current flowing through the resistor 63 between the R-phase power source bus 2 and the T-phase power source bus 4 of the three-phase AC power source 1 is approximately ½ cycle. The voltage drops due to the power capacity and cable impedance.
In the above description of the operation, there is no description of the resistor 53, the bidirectional thyristor 54, the primary voltmeter 56, and the secondary voltmeter 57 of the first switchgear 5. These devices are not necessary when the power supply path to the load 9 is changed from the first switchgear 5 to the second switchgear 6, but the power supply path to the load 9 is changed to the second switchgear. This is necessary when returning from 6 to the first opening / closing device 5, and the returning operation is the same as described above except that the operations of the first opening / closing device 5 and the second opening / closing device 6 are switched. Therefore, it is omitted.

Embodiment 2. FIG.
FIG. 6 is a block diagram showing a schematic configuration of the load change device according to the second embodiment of the present invention, FIG. 7 is an explanatory diagram for explaining the switching operation of the load change device according to the second embodiment of the present invention, and FIG. It is explanatory drawing explaining the switching operation failure of the load change apparatus in Embodiment 2. FIG. In the first embodiment, the case where the change command signal is output from the central control device 10 to the control devices 59 and 69 via the communication line 11 has been described. In the second embodiment, as shown in FIG. By manually operating the operation switch 12 mounted on one switchgear 5 and the operation switch 13 mounted on the second switchgear 6, a change command is issued to the control devices 59 and 69. When the route is changed so that the power supplied to the load 9 via the first switchgear 5 is supplied via the second switchgear 6, that is, the switch 51 of the first switchgear 5. A schematic operation from the state in which only the opening / closing switch 61 of the second opening / closing device 6 is closed to the state in which only the opening / closing switch 61 is closed will be described with reference to the time chart of FIG.

  First, when the operation switch 12 of the first opening / closing device 5 is pressed, the power supply from the opening / closing switch 51 of the first opening / closing device 5 is changed to the power supply via the bidirectional thyristor 52. Next, as the operation switch 13 of the second opening / closing device 6 is pressed, the bidirectional thyristor 52 is opened (OFF) after the bidirectional thyristor 64 is closed (ON), similarly to the operation described in the first embodiment. ) After that, the opening / closing switch 61 and the bidirectional thyristor 62 are closed (ON), and after a predetermined time, the bidirectional thyristor 62 and the bidirectional thyristor 64 are opened (OFF), and only the opening / closing switch 61 of the second opening / closing device 6 is opened. It is changed to a closed (ON) state.

  Here, the operation when the operation switch 12 and the operation switch 13 are pushed in the reverse order due to an erroneous operation will be described with reference to the time chart of FIG. When the operation switch 12 and the operation switch 13 are pressed in the reverse order, the bidirectional thyristor 64 of the second opening / closing device 6 is closed (ON) while the opening / closing switch 51 of the first opening / closing device 5 is closed. ) Since the opening / closing switch 51 of the first switching device 5 does not open (OFF) even if the current value of the ammeter 55 increases, the R-phase power source bus 2 and the T-phase power source bus 4 of the three-phase AC power source 1 In the meantime, the state continues to be connected by the resistor 63 of the second switchgear 6, and current continues to flow between the R-phase power source bus 2 and the T-phase power source bus 4 of the three-phase AC power source 1. Here, the control device 69 of the second switchgear 6 confirms the value of the ammeter 65 at the time when 3/4 period has elapsed in the voltage waveform from the timing when the bidirectional thyristor 64 is closed (ON). Since the current at the timing when 3/4 cycle has elapsed with respect to the value of the ammeter 65 from the timing when the bidirectional thyristor 64 is closed (ON) to the 1/2 cycle, the state of the first switching device 5 is It can be determined that this is a short circuit. For this reason, the control device 69 of the second opening / closing device 6 enters the state before the operation by opening (OFF) the bidirectional thyristor 64 without closing (ON) the opening / closing switch 61 and the bidirectional thyristor 62, and changes the load. The operation is cancelled.

  As described above, by providing the operation switch 12 in the first opening / closing device 5 and the operation switch 13 in the second opening / closing device 6, the central control device 10 and the communication line 11 become unnecessary, and the scale becomes smaller. The equipment can improve the unbalanced state of the three-phase AC circuit.

In the description of the first embodiment and the second embodiment, as an example, the phase between the R-phase power supply bus 2 and the S-phase power supply bus 3 is the first phase and the load between the first phases is the first. Assuming that the phase between the S-phase power source bus 3 and the T-phase power source bus 4 is the second phase, the load between the second phases is the second load, and the first load is the second load. However, the present invention is not limited to this between the first phase and the second phase, and any of the power buses of the R phase, S phase, and T phase is not limited to this. The operation for changing the power supply path to the load 9 is the same. Further, the first switchgear 5 and the second switchgear 6 can be used by being connected via a transformer instead of being directly connected to the power bus.
In addition to eliminating the unbalanced state of the three-phase AC circuit due to load fluctuations described in the first and second embodiments, the present invention is not caused by factors on the power source side by a distributed power source such as photovoltaic power generation. It is also applicable to canceling the equilibrium state.
It should be noted that within the scope of the present invention, the embodiments can be freely combined, or the embodiments can be appropriately modified or omitted.

1 Three-phase AC power supply, 2 R phase power supply bus, 3 S phase power supply bus, 4 T phase power supply bus, 5 First switchgear, 6 Second switchgear, 7 Secondary load bus, 8 Secondary side Load bus, 9 loads, 10 central controller, 11 communication lines.

Claims (6)

  1. A load changing device that changes power to be supplied from a second phase to a load that is supplied with power from a first phase in a three-phase AC circuit, and from the first phase to the load. While supplying power via the first switchgear and connecting the second switchgear in an open state from between the second phase, the first switchgear includes a first switch and a first switch A first parallel connection body of bidirectional switching elements, and a first ammeter provided on a load side of the first parallel connection body, wherein the second switchgear is a second switch And a second parallel connection body of the second bidirectional switching element and a third bidirectional switching element in which a resistor is connected in series, and a first provided on the power supply side across the second parallel connection body Voltmeter and second voltmeter provided on the load side And a second ammeter, and a timing for opening the first switchgear and a timing for closing the second switchgear depending on the values of the first ammeter and the second ammeter. Control means for controlling the power supply to the load from the first phase to the second phase without causing a short-circuit between the second phase by determining A load changing device comprising a step of turning on the third bidirectional switching element when the value of the second voltmeter becomes equal to the value of the second voltmeter.
  2.   The switching control by the control means includes both a procedure of turning on the first bidirectional switching element and turning off the first open / close switch while the first open / close switch is on, and then the third switch. A procedure for turning off the first bidirectional switching element after turning on the bidirectional switching element, and a second time after turning on the second open / close switch and the second bidirectional switching element after a predetermined time. The load changing apparatus according to claim 1, further comprising a procedure for turning off the bidirectional switching element and the third bidirectional switching element.
  3.   3. The load changing device according to claim 1, wherein the first to third bidirectional switching elements are bidirectional thyristors.
  4.   4. The load changing device according to claim 1, wherein the first opening / closing device and the second opening / closing device have the same configuration. 5.
  5.   A central control device that detects an unbalanced state in the three-phase AC circuit and issues a change command for switching power supply to the load to the first switchgear and the second switchgear; The load changing device according to any one of claims 1 to 4, wherein the load changing device is provided.
  6.   The operation switch which issues the change command for switching the power supply with respect to the said load provided in said 1st switchgear and said 2nd switchgear was provided. The load changing device according to the item.
JP2013186899A 2013-09-10 2013-09-10 Load change device Active JP6234125B2 (en)

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JP2773763B2 (en) * 1993-03-22 1998-07-09 日本碍子株式会社 High-voltage three-phase distribution line phase switching device
JPH07222361A (en) * 1994-01-31 1995-08-18 Ngk Insulators Ltd Method and apparatus for switching phase of three-phase distribution line
JP3327836B2 (en) * 1998-03-26 2002-09-24 エナジーサポート株式会社 Phase switching device for distribution lines
JP2009124845A (en) * 2007-11-14 2009-06-04 Kansai Electric Power Co Inc:The Power supply switching device and power supply switching method
JP2010250967A (en) * 2009-04-10 2010-11-04 Fuji Electric Systems Co Ltd Fuel cell power generating system and control method for the same
JP5410837B2 (en) * 2009-05-20 2014-02-05 三菱電機株式会社 Transformer load switching device

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