JP5521439B2 - Power generation system - Google Patents

Description

  The present invention relates to a power generation system, and more particularly to a power supply circuit for an auxiliary machine of a fuel cell in a power generation system using a fuel cell.

  A power generation system using a fuel cell includes a so-called auxiliary machine such as a blower or a pump as a peripheral device for operating the fuel cell. These auxiliaries are supplied with power from the fuel cell side when the fuel cell is generating power (during steady operation), and when the fuel cell is not generating power (during start-up stop or when the fuel cell is started from start-up) Since it is desirable to receive power supply from the commercial power supply system side during preparation for starting up to the point of), the conventional power generation system employs a circuit configuration as shown in FIG. 2 to supply power to the auxiliary equipment. (For example, refer to Patent Document 1).

  In FIG. 2, a is a fuel cell power generation unit (stack), b is a converter unit that converts a DC voltage output from the power generation unit a into a predetermined voltage, and c is a DC voltage boosted by the converter unit b. An inverter unit for converting the voltage into an AC voltage (for example, AC 200V) and outputting it to the commercial power supply system d side, d indicates the commercial power supply system, and the converter unit b and the inverter unit c are DC link capacitors. (DC link part) It is connected via e.

  In this power generation system, as the power source of the auxiliary machine f, the DC power output from the power generation part a when the fuel cell is generating power is converted into a predetermined voltage (for example, DC 24V) to convert the auxiliary machine f A first auxiliary power unit g provided with a DC / DC converter for supplying to the power source, and AC power supplied from the commercial power source system d when the fuel cell is not generating power is converted into a predetermined DC voltage (for example, DC 24V) And a second auxiliary power supply unit h having an AC / DC inverter for supplying to the auxiliary device f, and switching the contacts A and B of the switch circuit unit i according to the presence or absence of power generation by the fuel cell. These power supply units g and h were used.

  As another method, an AC bridge circuit that converts AC power from a commercial power supply system to DC is connected to the DC link unit, and an auxiliary power unit (DC / DC converter) is connected to the DC link unit. There are some (see, for example, Patent Document 2).

  By the way, in the case of supplying power to the auxiliary machine through the DC link unit as described above, an AC bridge circuit that converts AC power from a commercial power source into DC is provided, and this AC bridge circuit is activated during stoppage of the fuel cell. The power from the commercial power supply system is supplied to the DC link section through the inverter, and the inverter is operated reversely while the fuel cell is being prepared for startup to supply the power from the commercial power supply system to the DC link section through the inverter section. The one configured in this way has also been proposed.

JP 2008-53039 A JP 2006-42548 A

  However, the conventional power generation system having such a configuration has the following problems, and improvements have been desired.

  That is, in the circuit configuration shown in FIG. 2, two power sources, ie, the first auxiliary power unit g and the second auxiliary power unit h are required as the auxiliary power unit. In addition, since the fuel cell must avoid sudden current fluctuations in order to prevent the stack from deteriorating, the blower and pump of the auxiliary machine f are frequently turned on and off, so the power supply for the auxiliary machine as shown in FIG. In the configuration in which the part (first auxiliary power supply part g) is directly connected to the output side of the fuel cell (power generation part a), it is difficult to prevent sudden current fluctuations in the fuel cell due to fluctuations in the operating current of the auxiliary equipment. It was. That is, in the configuration of FIG. 2, it is difficult to prevent an inrush current of the fuel cell stack, and there is a possibility that the fuel cell is damaged.

  On the other hand, when power is supplied to the auxiliary machine through the DC link unit, such a problem of inrush current can be solved. However, if the inverter unit is operated in reverse during preparation for starting the fuel cell, the power or switch for driving the inverter unit during that period, that is, during preparation for starting from the time when the fuel cell is started until power generation is started. Electric power is required to maintain the circuit section on the inverter section side. In particular, since the fuel cell requires a time of 1 hour or more from the start to the start of steady operation for generating power, there has been a problem that the power consumption during start-up preparation becomes large.

  The present invention has been made in view of such problems, and an object of the present invention is to suppress rapid current fluctuations in the fuel cell and to reduce power consumption during startup (preparation for startup). It is to provide a small power generation system.

In order to achieve the above object, a power generation system according to claim 1 of the present invention includes a fuel cell, a converter that converts a DC voltage output from the fuel cell into a predetermined voltage, and a DC that is output from the converter. An inverter capable of performing a normal operation of converting a voltage into an AC voltage and supplying the commercial power supply system, and a reverse operation of converting the AC voltage supplied from the commercial power supply system into a DC voltage and outputting the DC voltage to the DC link unit; An AC bridge circuit unit that converts an AC voltage supplied from the commercial power supply system into a DC voltage and supplies the DC link unit, and which of the inverter unit and the AC bridge circuit unit is connected to the commercial power system A switch circuit unit to be selected and an auxiliary power supply unit connected to the DC link unit, and start power generation while the fuel cell is being started and stopped and after the fuel cell is started. Starting in preparation before, while the converter unit and the inverter unit and stop state, the DC link section as well as charge the DC link portion from the commercial power supply system by connecting the switch circuit to an AC bridge circuit portion Power is supplied to the auxiliary power source through the power supply.

  In the power generation system according to the first aspect, one auxiliary machine power supply unit is used as a power supply for auxiliary machines, and this auxiliary machine power supply unit supplies power via a DC link unit provided between the converter unit and the inverter unit. Configured to receive. That is, since the auxiliary machine power supply unit is configured to use the DC link voltage of the DC link unit as a power supply without being directly connected to the fuel cell 1, the power consumption (operating current) of the auxiliary machine fluctuates rapidly. However, the fluctuation is absorbed by the DC link portion and the inrush current is prevented from flowing to the fuel cell.

  Further, in the power generation system according to claim 1, the converter unit and the inverter unit are stopped during the start-stop of the fuel cell and during the start-up preparation, and the charging of the DC link unit between them operates the inverter unit. Therefore, the power consumption during preparation for starting up the fuel cell can be reduced.

  The power generation system according to a second aspect of the present invention is the power generation system according to the first aspect, wherein when the preparation for starting the fuel cell is completed, the switch circuit unit is connected while maintaining the stopped state of the converter unit. The inverter unit is switched to start the reverse operation of the inverter unit.

  That is, in the power generation system according to the second aspect, even when the preparation for starting the fuel cell is completed and the fuel cell starts power generation, the converter unit is stopped without immediately operating the converter unit, and the inverter unit is stopped. The reverse operation is started. That is, if the converter unit is operated in a state where the charging of the DC link unit is insufficient, a large amount of current flows from the fuel cell to the converter unit to charge the DC link unit, which may become an inrush current. Therefore, the power generation system according to claim 2 is configured such that the DC link unit is charged by the inverter unit prior to the start of the operation of the converter unit. Note that if the charging of the DC link part due to the reverse operation of the inverter part exceeds a certain level, the current flowing from the fuel cell side will decrease even if the converter part is operated, so the fuel cell enters the fuel cell as the converter part starts operating. The possibility of current flow is very low. By the way, with such a configuration, there is a possibility that an inrush current flows to the DC link portion due to the start of the reverse operation of the inverter unit. This is an inrush current to the DC link unit, and the reverse operation start of the inverter unit is started. At the time, the converter unit maintains the stopped state, so that no current change occurs on the fuel cell side (the current on the fuel cell side is 0).

  A power generation system according to a third aspect of the present invention is the power generation system according to the first or second aspect, characterized in that the auxiliary power supply unit is constituted by an insulated DC / DC converter.

  That is, in the power generation system according to the third aspect, since the auxiliary machine power supply unit is composed of an insulated DC / DC converter, the auxiliary machine is separated from the commercial power supply system by the auxiliary machine power supply unit.

  According to the present invention, since the auxiliary power supply section that supplies power to the auxiliary equipment is configured to receive power supply via the DC link section of the inverter, a plurality of power supply sections are provided as the power supply section for the auxiliary equipment. It can be configured with only a single power supply unit without the need. In addition, since this auxiliary power unit is not directly connected to the fuel cell, even if the power consumption (operating current) of the auxiliary device fluctuates rapidly, the current of the fuel cell does not fluctuate rapidly, and the stack of the fuel cell deteriorates. Can be prevented.

  In addition, charging of the DC link unit during start-stop of the fuel cell and preparation for start-up is performed by an AC bridge circuit unit that consumes less power while both the converter unit and the inverter unit are stopped. A power generation system with low power consumption is provided.

It is a circuit diagram which shows an example of schematic structure of the electric power generation system which concerns on this invention. It is a circuit diagram which shows an example of schematic structure of the conventional electric power generation system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic configuration of a power generation system according to the present invention. As shown in FIG. 1, this power generation system includes a fuel cell 1, a power conditioner 3 for connecting the fuel cell 1 to a commercial power supply system 2, and an auxiliary power supply unit 4 as main parts. Yes.

  The fuel cell 1 is a power generation device that generates power by supplying a fuel gas containing hydrogen such as natural gas and an oxidant gas containing oxygen such as air and causing a chemical reaction between hydrogen and oxygen. Is output as a DC voltage. The fuel cell 1 is classified into several types depending on the electrolyte used and the operating temperature (stack temperature). In this embodiment, the fuel cell 1 is a solid oxide fuel using an ion conductive ceramic as an electrolyte. A battery (SOFC) is used. Since the structure of the fuel cell 1 itself is known, detailed description thereof is omitted here, and the main points of the present invention will be described below.

  In FIG. 1, 5 indicates a power generation unit (stack) of the fuel cell 1. Since the operating temperature of SOFC is as high as several hundred degrees (for example, about 800 to 1000 ° C.), this fuel cell 1 requires one hour or more to prepare for startup from the start of startup to the start of power generation. When the power generation operation (steady operation) is started, the power generation unit 5 outputs a DC voltage of 100 to 160 V, for example.

  The auxiliary machine 6 is a peripheral device for operating the fuel cell 1 and is composed of an electrical load (not shown) such as a blower or a pump that operates when the fuel cell 1 is in preparation for startup or during a power generation operation. ing. In the present embodiment, the electric load constituting these auxiliary machines 6 is constituted by a motor or the like driven by a DC voltage (for example, DC 24V). In addition, since the blower and pump which comprise the auxiliary machine 6 repeat on / off during starting of the fuel cell 1 and preparation for starting, the fluctuation | variation of the operating current during operation | movement of these electric loads is very severe.

  The FC control unit 7 is a control device including a microcomputer as a control center, and is obtained from various sensors (not shown) that monitor the output voltage and output current of the power generation unit 5, the state of the auxiliary machine 5, and the like. And the operation | movement of each part (including the auxiliary machine 6) of the fuel cell 1 is controlled based on the information obtained by communication with the PC control part 15 mentioned later.

  The commercial power supply system 2 includes a power supply line and a distribution board (not shown) for supplying AC power supplied from the commercial power supply 8 (for example, AC 200 V) to an electric load in the home (not shown), In the present embodiment, the fuel cell 1 connected via the power conditioner 3 is grid-connected.

  The power conditioner 3 is a device for connecting the fuel cell 1 to the commercial power supply system 2, and as shown in FIG. 1, a converter unit 10, an inverter unit 11, a DC link unit 12, an AC bridge, and the like. The circuit part 13, the switch circuit part 14, and the PC control part 15 are provided as main parts.

  The converter unit 10 includes a DC / DC converter that converts a DC voltage output from the fuel cell 1 into a predetermined DC voltage (for example, DC 375 to 405 V). That is, the DC power output from the power generation unit 5 of the fuel cell 1 is boosted by the converter unit 10 so that the inverter unit 11 described below can generate AC200V, and the inverter unit 11 via the DC link unit 12. To be supplied. The converter unit 10 is an insulated DC / DC converter, and the fuel cell 1 and the commercial power supply system 2 are separated by the converter unit 10.

  The inverter unit 11 is a grid interconnection inverter connected to the converter unit 10 via the DC link unit 12, and the DC voltage output from the converter unit 10 is changed to a predetermined AC voltage (for example, AC 200V). A DC / AC inverter capable of performing a forward operation that is converted and supplied to the commercial power supply system 2 and a reverse operation that converts the AC voltage supplied from the commercial power supply system 2 into a predetermined DC voltage and outputs the DC voltage to the DC link unit 12 It consists of

  A switch circuit unit 14 is provided on the commercial power system side of the inverter unit 11, and the inverter unit 11 is connected to the contact A side of the switch circuit unit 14, and is connected to the commercial power system via the switch circuit unit 14. 2 (details will be described later). Further, a large-capacity DC link capacitor 12a is connected in parallel with the converter unit 10 on the converter unit side of the inverter unit 11 (that is, the DC link of the inverter), thereby forming the DC link unit 12. Yes.

  The AC bridge circuit unit 13 is a rectifier circuit for converting an AC voltage supplied from the commercial power supply system 2 (commercial power supply 8) into a predetermined DC voltage (for example, DC 280 V) and supplying the DC voltage to the DC link unit 12. As shown in FIG. 1, the input side is connected to the contact B side of the switch circuit unit 14, and the output side is connected to the DC link unit 12. The AC bridge circuit 13 may be provided with a smoothing circuit.

  The switch circuit unit 14 is configured by a changeover switch that is interposed in a connection portion between the commercial power supply system 2 and the power conditioner 3 and selects which of the inverter unit 11 or the AC bridge circuit unit 13 is connected to the commercial power supply system 2. Is done. The contact of this switch circuit unit 14 is configured to be controllable by a PC control unit 15 described later, and the commercial power supply system 2 and the inverter unit 11 are connected by connecting the switch contact to the A side. Further, the commercial power supply system 2 and the AC bridge circuit unit 13 are connected by connecting the switch contact to the B side.

  In the present embodiment, the switch circuit unit 14 also functions as a grid connection switch that links the power generation system of the fuel cell 1 and the commercial power supply system 2. When the grid connection is not performed, the switch contact is a contact point. It is configured to connect to the B side. And the relay which comprises the contact of this switch circuit part 14 is set as the structure which connects a contact to the B side when a relay drive circuit (not shown) is de-energized, and a contact is A by energizing a relay circuit. It is set as the structure connected to the side.

  In the present embodiment, the switch circuit unit 14 is used as a system interconnection switch. However, the system connection switch can be provided separately from the switch circuit unit 14. That is, it is also possible to provide a switch circuit (system connection relay) capable of disconnecting the system connection separately from the switch circuit unit 14 in series.

  The PC control unit 15 is a control device including a microcomputer as a control center, and includes various sensors (not shown) that monitor the input voltage, input current, stack temperature, and the like from the fuel cell 1 (power generation unit 5). While controlling the operation of each part of the power conditioner 3 based on information obtained, information obtained from the FC control unit 7 of the fuel cell 1, and information obtained from a remote control (operation unit) of the power generation system (not shown) The power generation system as a whole is also controlled.

  Specifically, the PC control unit 15 performs control of operation or stop of the converter unit 10 and the inverter unit 11, switching control of switch contacts of the switch circuit unit 14, and the like, and FC control of the fuel cell 1. Various commands (for example, commands for starting or stopping the fuel cell 1) are issued to the unit 7. The PC control unit 15 is configured so that its drive power is supplied from the DC link unit 12 so that the fuel cell 1 can operate even when the fuel cell 1 is not generating power, as in the auxiliary machine 6 described later. Has been.

  The auxiliary machine power supply unit 4 is a power supply device that generates a DC voltage (for example, DC 24V) to be supplied to the auxiliary machine 6 of the fuel cell 1. In the present embodiment, the auxiliary machine power supply unit 4 is an insulated DC / DC / DC unit. A DC converter is used. Specifically, the auxiliary power supply unit 4 is configured such that its input side is connected to the DC link unit 12 and receives DC power from the DC link unit 12, and its output side is connected to the auxiliary unit 6. Has been. In addition, since the auxiliary power supply unit 4 uses an insulating DC / DC converter as described above, the auxiliary power supply unit 4 cuts off the auxiliary machine 6 (fuel cell 1) and the commercial power supply system 2. Has been.

  In the present embodiment, a 540 μF capacitor is used as the DC link capacitor 12a. Further, a 150 μF capacitor is used as a capacitor (not shown) on the input side of the auxiliary power supply unit 4. Further, a 15 μF capacitor is used as an input side capacitor of a power source (not shown) for the PC control unit interposed between the DC link unit 12 and the PC control unit 15.

  The operation of the power generation system configured as described above (specifically, the method of supplying power to the auxiliary machine 6) will be described.

  In this power generation system, when the fuel cell 1 is not in a power generation operation (steady state operation), in other words, when the fuel cell 1 is in a start-stop state or in preparation for start-up, the PC control unit 15 10 is stopped, and the contact of the switch circuit unit 14 is connected to the B side.

  In this state, AC power supplied from the commercial power source 8 acts to charge the DC link unit 12 (DC link capacitor 12a) via the AC bridge circuit unit 13, and the auxiliary power unit 4 has a DC link. Power from the unit 12 is supplied. Specifically, in the present embodiment, AC 200V is used as the commercial power supply 8, and at this time, the DC link unit 12 is charged to DC 280V (= 200√2V). At this time, the fuel cell 1 is not generating power and the converter unit 10 is also stopped, so that no power is supplied from the fuel cell 1 side to the auxiliary power source unit 4.

  On the other hand, when the fuel cell 1 starts a power generation operation, in other words, the fuel cell 1 starts from a start-stop state to a predetermined start-up preparation (for example, supply of fuel gas or oxidant gas, raises the stack to the operating temperature) When the fuel cell 1 starts steady operation, the PC control unit 15 first connects the contact of the switch circuit unit 14 to the A side and starts the reverse operation of the inverter unit 11. Here, the FC control unit 7 determines whether the preparation for starting the fuel cell 1 is completed based on the output voltage of the power generation unit 5 and the stack temperature (operation temperature), and the result is transmitted to the PC control unit 15. Is done.

  Thus, the DC link unit 12 is charged by the output power of the inverter unit 11 by connecting the contact of the switch circuit unit 14 to the A side. That is, AC power supplied from the commercial power supply system 2 is converted to DC by the inverter unit 11 and the DC link unit 12 is charged. In this state, the auxiliary power supply unit 4 is supplied with DC power generated by the reverse operation of the inverter unit 11 through the DC link unit 12. Note that when the reverse operation of the inverter unit 11 is started, the PC control unit 15 maintains the stopped state of the converter unit 10.

  By the way, when the DC link unit 12 is charged using the inverter unit 11 before the converter unit 10 is operated in this way, the voltage (DC link voltage) of the DC link unit 12 increases toward the target voltage (for example, DC 390 V). However, in the power generation system shown in the present embodiment, when the DC link voltage exceeds the predetermined threshold value X set in advance and approaches the target voltage, the PC control unit 15 causes the time point (to the threshold value X). At the time when the DC link voltage rises, the operation of the converter unit 10 is started, and the output of the converter unit 10 is gradually increased.

  Specifically, the converter unit 10 controls the DC link voltage to be the target voltage, while the inverter unit 11 gradually decreases the target value of the voltage supplied to the DC link unit 12 from the operation start point of the converter unit 10. To control. Thereby, the voltage supplied to the DC link part 12 from the inverter part 11 falls gradually. At this time, the converter unit 10 operates to maintain the DC link voltage at the target voltage, and accordingly, the current supplied from the converter unit 10 to the DC link unit 12 gradually increases.

  Thus, in the present embodiment, the converter unit 10 is configured to gradually increase the output from the start of operation, so the output current of the power generation unit 5 of the fuel cell 1 that supplies current to the converter unit 10 is also moderate. As a result, the rapid inrush current is prevented from flowing to the power generation unit 5 of the fuel cell 1.

  Here, the threshold value X that determines the timing for starting the operation of the converter unit 10 is set based on the target voltage of the DC link voltage. Since the DC link unit 12 is configured by a large-capacity DC link capacitor 12a, the target voltage during the reverse operation of the inverter unit 11 is set to a value that can fully charge the DC link capacitor 12a. The threshold value X is set to a value as close as possible to the target voltage (for example, about 95% of the target voltage).

  This is because if the difference between the threshold value X and the target voltage is large (threshold value X is too low with respect to the target voltage), charging is performed by the output of the converter unit 10 when the converter unit 10 starts operation. This is because the amount of energy that must be increased increases, so that the current flowing through the fuel cell 1 also increases. Therefore, this threshold value X is an allowable value of a variation rate of a current (inrush current) flowing through the fuel cell 1 when the converter unit 10 is operated (in the present embodiment, this allowable value is assumed to be 1 A / second). It is set not to exceed. That is, there is a correlation between the threshold value X and the allowable value. When a fuel cell having a large allowable value is used, the difference between the threshold value and the target voltage can be set large. .

  Incidentally, in the present embodiment, since the allowable value is 1 A / second and the target voltage of the DC link voltage is DC 390 V, the threshold value X is set to DC 370 V, which is 95% of 390 V. This is an empirical value obtained through experiments by the applicant. When the threshold value X is set to less than 95% of the target voltage, the inrush current of the fuel cell 1 exceeds the allowable value (1 A / second). There is a high possibility that The threshold value X can be a value closer to the target voltage as long as it is 95% or more of the target voltage.

  Then, by continuing this control, that is, the control for increasing the output of the converter unit 10 while gradually decreasing the reverse operation output of the inverter unit 11, the inverter unit 11 finally operates in the normal operation (output from the converter unit 10). Operation to convert the DC voltage to AC voltage (AC200V) and supply it to the commercial power supply system 2), the current is output to the commercial power supply system 2 side, and the electric power generated by the fuel cell 1 is converted into household power. To be supplied.

  As described above, in the power generation system according to the present invention, the auxiliary power supply unit 4 that supplies electric power to the auxiliary machine 6 is configured to receive power supply through the DC link unit 12. The auxiliary power supply unit 4 is not directly connected to the fuel cell 1, so that even if the operating current of the auxiliary device 6 fluctuates rapidly, the current of the fuel cell 1 increases rapidly. The stack of the fuel cell 1 can be prevented from deteriorating.

  Further, the charging of the DC link unit 12 during the start-stop of the fuel cell 1 and the preparation for start-up is an AC bridge circuit that consumes less power than the inverter unit 11 with both the converter unit 10 and the inverter unit 11 stopped. Since it is performed by the unit 13, it is possible to reduce power consumption during preparation for starting up the fuel cell 1. In addition, as the switch circuit unit 14 that selects the AC bridge circuit unit 13 at this time, a relay that selects the AC bridge circuit unit 13 side when the relay drive circuit is not energized is used. Power consumption in the switch circuit unit 14 can also be suppressed, and a power generation system with higher power saving effect can be supplied.

  The above-described embodiments show preferred embodiments of the present invention, and the present invention is not limited to these, and various design changes can be made within the scope of the invention.

  For example, in the above-described embodiment, a case where a solid oxide fuel cell (SOFC) is used as the fuel cell 1 has been described. (PEFC) or the like can also be used.

  Further, in the above-described embodiment, the configuration of the power generation system alone has been described. However, this power generation system recovers exhaust heat generated in the fuel cell 1 by exhaust heat recovery means (for example, a heat exchanger) and generates hot water. It can also be applied as a component of a cogeneration system, such as being used as a heat source.

  In the above-described embodiment, the case where the PC control unit 15 is configured to monitor the stack temperature of the fuel cell 1 and to perform various commands from the PC control unit 15 to the FC control unit 7 is shown. However, the control that the PC control unit 15 and the FC control unit 7 are responsible for (the role sharing between them) can be changed as appropriate. That is, for example, the stack control is configured to be performed by the FC control unit 7, or the FC control unit 7 sets the start / stop command of the fuel cell 1, the operation target value, and the like to the PC control unit 15. It can also be configured to transmit.

1 Fuel Cell 2 Commercial Power Supply System 3 Power Conditioner 4 Auxiliary Power Supply Unit 5 Power Generation Unit (Stack)
6 Auxiliary machine 7 FC control unit 8 Commercial power supply 10 Converter unit 11 Inverter unit 12 DC link unit 13 AC bridge circuit unit 14 Switch circuit unit 15 PC control unit X Threshold

Claims (3)

A fuel cell;
A converter for converting a DC voltage output from the fuel cell into a predetermined voltage;
The direct operation of converting the DC voltage output from the converter unit into an AC voltage and supplying it to the commercial power supply system, and the reverse operation of converting the AC voltage supplied from the commercial power supply system into a DC voltage and outputting it to the DC link unit An inverter unit capable of operation;
An AC bridge circuit unit that converts an AC voltage supplied from the commercial power supply system into a DC voltage and supplies the DC link unit;
A switch circuit unit for selecting which of the inverter unit or the AC bridge circuit unit is connected to a commercial power supply system;
An auxiliary machine power supply unit connected to the DC link unit,
During the start-stop of the fuel cell and during the start-up preparation from the start-up of the fuel cell to the start of power generation, the switch circuit unit is set to the AC bridge circuit unit side while the converter unit and the inverter unit are stopped. A power generation system comprising: connecting and charging the DC link unit from a commercial power supply system and supplying power to the auxiliary power unit through the DC link unit .   2. When the preparation for starting the fuel cell is completed, the connection of the switch circuit unit is switched to the inverter unit side and the reverse operation of the inverter unit is started while maintaining the stopped state of the converter unit. The power generation system according to 1.   The power generation system according to claim 1 or 2, wherein the auxiliary machine power supply unit is configured by an insulated DC / DC converter.

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