JP2013078183A - Power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation system capable of preventing a power generation device from deteriorating in an early stage by suppressing an in-rush current while avoiding a decrease in efficiency of a power conditioner.SOLUTION: In a power generation system including a capacitor 32 between plus-electrode and minus-electrode lines connecting an output section of a fuel cell device 1 and an input part of a power conditioner 3 to each other, a switch 12 for output of the fuel cell device 1 and a resistor 13, as well as and a relay 14 with a normally closed contact which short-circuits the resistor 13 are connected in series to an upstream-side line of the capacitor 32. When supplying the output of the fuel cell device 1 to the power conditioner 3, an FC control part 11 performs control to close the switch 12, and then closes the relay 14 on condition that an input voltage to the power conditioner 3 reaches or exceeds a predetermined voltage.

Description

  The present invention relates to a power generation system, and more particularly to a technique for suppressing inrush current to a capacitor provided in an input portion of a power conditioner in a power generation system using a fuel cell as a power generation device.

  In a power generation system in which a DC power generation device such as a fuel cell device is connected to a power system such as a commercial power supply, a power conditioner that is an inverter device is provided between the power generation device and the power system.

  As is well known, this type of power conditioner includes a converter that boosts DC power supplied from a power generator, an inverter that converts DC power output from the converter into AC power that can be connected to a power system, and The system interconnection switch that connects the inverter and the power system, and these control units are provided as main parts, and the output unit of the power generator and the converter that is the input unit of the power conditioner are connected. A capacitor (electrolytic capacitor) is provided between the positive electrode and negative electrode lines (see, for example, Patent Document 1).

FIG. 3 of the republished WO2007 / 096994.

  By the way, the fuel cell used for a power generator has a problem that it deteriorates early when a current is passed rapidly. Therefore, as described above, in the configuration in which the capacitor is provided at the input portion of the power conditioner, when a fuel cell is used for the power generation device, a large rushing into the capacitor occurs when the operation of the power generation device starts, that is, when power generation by the fuel cell starts. There is a problem that current flows and causes early deterioration of the fuel cell.

  In order to solve such a problem, the applicant studied to provide an inrush current prevention circuit upstream of the capacitor provided in the input part of the power conditioner, that is, on the power generator side of the capacitor.

  FIG. 3 shows a power generation system provided with such an inrush current prevention circuit. In the figure, a is a fuel cell device that is a power generator, b is a power conditioner, c is disposed between the positive and negative lines connecting the output part of the fuel cell device a and the input part of the power conditioner b. The capacitor is shown. In addition, d is a normally open contact (a contact) switch for turning on / off the output of the power generator a disposed on the line. In such a power generation system, as the inrush current prevention circuit, a current limiting resistor e is connected in series with the switch d, and the resistor e is short-circuited across the resistor e. A contact f (contact a) is provided.

  As described above, in the configuration in which the inrush current prevention circuit including the resistor e and the normally open contact relay f is provided, when the fuel cell device a is not generating power (when the power conditioner b is on standby), FIG. As shown in FIG. 3 (a), both the switch d and the relay f are opened, and when the fuel cell device a is generating power (when the power conditioner b is in operation), the operation is started. Unless the inrush current to the capacitor c is prevented, both the normally open contact switch d and the relay f are closed as shown in FIG. 3B.

  However, the fuel cell device a used in the power generation device continues power generation for a long period (for example, about one month) once power generation is started. That is, the power conditioner b having the fuel cell device a as a power generation device has an extremely long operation time than the standby time. Therefore, in the configuration using a normally open contact relay that consumes power to close the contact as the relay f used in the inrush current prevention circuit, the power is maintained in the relay f for a long period of time when the fuel cell device a continues to generate power. However, since the driving power of the relay f is supplied from the power conditioner b side, there is a problem that the efficiency of the power conditioner b is reduced. .

  The present invention has been made in view of such problems, and the object of the present invention is to prevent the deterioration of the efficiency of the power conditioner while suppressing the inrush current and preventing the early deterioration of the power generation apparatus. It is to provide a power generation system that can do this.

  In order to achieve the above object, a power generation system according to claim 1 of the present invention includes a power generation device that generates DC power and a power conditioner that converts DC power supplied from the power generation device into AC power. In the power generation system provided with a capacitor between the positive electrode and the negative electrode line connecting the output unit of the power generator and the input unit of the power conditioner, the output of the power generator is connected to the upstream line of the capacitor. A switch to be turned on / off and a resistor are connected in series, and a relay with a normally closed contact for short-circuiting the resistor is connected to both ends of the resistor. It is set to open the contact of the closed relay, and when supplying the output of the power generator to the power conditioner, the switch is closed. After the control, and having a control configuration in which the input voltage of the power conditioner performs control to close the relay of the normally closed contact condition to become higher than a predetermined voltage.

  In the power generation system according to claim 1, as a relay that short-circuits a resistor of an inrush current prevention circuit connected to a switch that turns on and off the output of the power generation device, normally closed that does not consume power to close the contact Since the contact (b contact) relay is used, when the power generator is generating power (during operation of the power conditioner), no power is consumed in the relay to close the contact. For this reason, it is not necessary for the power generator to supply power to operate the relay from the power conditioner during power generation, so the inrush current to the input capacitor of the power conditioner is suppressed without degrading the efficiency of the power conditioner. can do.

  A power generation system according to a second aspect of the present invention is the power generation system according to the first aspect, wherein the control unit, the switch, the resistor, and the normally closed contact relay are all provided in the power generation apparatus. It is characterized by being.

  That is, in the power generation system according to claim 2, the power generation device includes both a switch for turning on / off the output of the power generation device, an inrush current prevention circuit connected to the switch, and a control unit thereof. It is done. Therefore, by providing the control unit that controls the power generation unit or the like in the power generation device with the function of the control unit, necessary measures such as a safe stop of output using the switch according to the setting of the control unit of the power generation device. Can be taken.

  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, wherein the switch is a relay with a normally open contact.

  That is, in the power generation system according to claim 3, since a relay with a normally open contact is used as the switch, when the power generator is not generating power, that is, when the switch needs to be opened. Thus, it is possible to prevent power from being consumed by the switch.

  A power generation system according to a fourth aspect of the present invention is the power generation system according to the second or third aspect, wherein the power conditioner includes voltage measurement means for measuring an input voltage from the power generation device. Information on the input voltage of the power conditioner measured by the voltage measuring means is configured to be transmitted to the control unit provided in the power generator via the control unit of the power conditioner. .

  That is, in the power generation system according to claim 4, since the power conditioner is provided with voltage measuring means for measuring the input voltage input from the power generator to the power conditioner, the input voltage measured by the voltage measuring means is measured. This information can be transmitted to the control unit using a communication function between the power conditioner and the power generation device (communication function between the control unit of the power conditioner and the control unit of the power generation device).

  According to the present invention, as a relay that short-circuits a resistor of an inrush current prevention circuit that is connected to a switch that turns on and off the output of the power generation device, a relay that is a normally closed contact that does not consume power to close the contact. Therefore, when the generator is generating power (during operation of the power conditioner), power is not consumed to close the contact of the relay of the inrush current prevention circuit. Therefore, it is not necessary to supply the power for operating the relay from the power conditioner during power generation by the power generation device. The inrush current to the capacitor for the input of the power conditioner can be suppressed without reducing the efficiency of the power conditioner.

  Therefore, by applying to a power generation system using a power generation device in which the standby time of the power conditioner is extremely shorter than the operation time, such as a fuel cell device, the power consumption in the inrush current prevention circuit is small, and the power It is possible to provide a power generation system that suppresses the decrease in efficiency of the conditioner.

It is a circuit diagram which shows an example of schematic structure of the electric power generation system which concerns on this invention, Fig.1 (a) shows the state in which a power conditioner is standing by, FIG.1 (b) shows the state at the beginning of operation | movement of a power conditioner. FIG. 1C shows a state in which the power conditioner is operating. It is a flowchart which shows the operation | movement procedure of the inrush current prevention circuit in the power generation system. FIG. 3A shows an example of a schematic configuration of a power generation system provided with an inrush current prevention circuit for an input capacitor of a conventional power conditioner. FIG. 3A shows a state where the power conditioner is in a standby state, and FIG. Indicates the state in which the inverter is operating.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of a power generation system according to the present invention. The power generation system shown in FIG. 1 is a power generation system that uses a fuel cell as a power generation device, and includes a fuel cell device 1, a power system 2, and a power conditioner 3 as main parts.

  The fuel cell device 1 is a power generation device having a well-known configuration for generating DC power by chemically reacting a fuel gas containing hydrogen such as natural gas and an oxidant gas containing oxygen such as air. The device 1 includes an FC control unit (control unit) 11 that controls each unit of the fuel cell device 1 in addition to a power generation unit (stack) and peripheral devices (auxiliary equipment) of the power generation unit (not shown).

  The FC control unit 11 is a control device provided with a microcomputer (not shown) as a control center, and information obtained from various sensors (not shown) for monitoring the output voltage and output current of the power generation unit, the state of auxiliary equipment, and the like. And the operation of each part of the fuel cell device 1 (for example, start or stop power generation in the power generation unit) based on information obtained by communication with the PC control unit 31 of the power conditioner 3 to be described later It is configured. And especially in this embodiment, this FC control part 11 is comprised so that the switch 12 of the switch 12 mentioned later and the normally closed contact relay 14 may be controlled. The FC control unit 11 is configured to operate by receiving power supply from the power conditioner 3, and can perform drive control of the relay 14 described later even when the power generation unit is not generating power. Yes.

  In FIG. 1, reference numeral 11 a denotes a control board provided in the FC control unit 11. Various electrical components (for example, a communication circuit with the PC control unit 31 and a power supply circuit of the fuel cell device 1) constituting the FC control unit 11 are mounted on the control board 11a. A switch 12 that turns on / off the output of DC power generated by the battery device 1 and an inrush current prevention circuit that includes a resistor 13 and a relay 14 are provided. In the illustrated example, for convenience of illustration, the control board 11 a is shown outside the fuel cell device 1, but the control board 11 a is provided inside the fuel cell apparatus 1 together with the FC control unit 11.

  The switch 12 is composed of a normally open contact (a contact) relay whose drive circuit (not shown) is controlled by the FC control unit 11, and the DC power output unit and the power condition of the fuel cell device 1. It is arranged in series with the positive and negative feed lines connecting the input part of the na 3. When the fuel cell device 1 starts generating power, the FC control unit 11 closes the contact, and the DC power output from the fuel cell device 1 is supplied to the power conditioner 3.

  The resistor 13 is an electrical resistance connected in series with the switch 12 and functions as a current limiting resistor that suppresses inrush current in the inrush current prevention circuit (details will be described later). The relay 14 is a normally closed contact (b contact) relay connected to both ends of the resistor 13 so as to short-circuit the resistor 13, and the drive circuit (not shown) of the relay 14 is also described above. It is controlled by the FC control unit 11. The switch 12, the resistor 13, and the relay 14 are all provided upstream of the input capacitor 32 of the power conditioner 3, which will be described later, that is, on the fuel cell device 1 side as viewed from the capacitor 32. It is arranged.

  The electric power system 2 is composed of a commercial power supply (for example, single-phase AC200V), and is connected to an electrical load (not shown) and a power conditioner 3 via a distribution board (not shown).

  The power conditioner 3 is an inverter device that converts DC power generated by the fuel cell device 1 into AC power that can be linked to the power system 2, and is a converter that boosts the DC power supplied from the fuel cell device 1. (DC / DC converter), an inverter (DC / AC inverter) that converts DC power output from the converter into AC power that can be linked to the power grid 2, and a grid connection that connects the inverter to the power grid 2 Main components are a system relay (all not shown) and a PC control unit 31 that controls the operation of each part of the power conditioner 3 including the converter, the inverter, and the system interconnection relay.

  A capacitor (electrolytic capacitor) 32 is connected between the input portion of the power conditioner 3, that is, between the positive and negative power supply lines connected to the output portion of the fuel cell device 1, and the fuel cell. A voltage sensor (voltage measuring means) 33 for measuring an input voltage (voltage between positive and negative power supply lines) input from the device 1 to the power conditioner is provided. Note that both the capacitor 32 and the voltage sensor 33 are provided inside the power conditioner 3.

  The PC control unit 31 is a control device provided with a microcomputer (not shown) as a control center, and information obtained from various sensors provided in the power conditioner 3 such as the voltage sensor 33, FC control of the fuel cell device 1 The operation of each part of the power conditioner 3 is controlled based on information obtained from the unit 11 and further information obtained from a remote controller (operation unit) of the power conditioner 3 (not shown). In particular, in the present embodiment, information on the input voltage to the power conditioner 3 measured by the voltage sensor 33 is configured to be transmitted to the FC control unit 11 through a communication circuit (not shown).

  Thus, the operation of the power generation system configured as described above will be described with reference to FIGS. 1 (a) to 1 (c) and FIG.

  In the power generation system shown in the present embodiment, when the power generation unit of the fuel cell device 1 is not generating power, the power conditioner 3 stands by in a stopped state (see FIG. 1A). At this time, the FC control unit 11 maintains the normally open contact switch 12 in the open state and controls the normally closed contact relay 14 to be in the open state. That is, the FC control unit 11 does not supply power to the drive circuit of the normally open contact switch 12 when the power generation unit of the fuel cell device 1 is not generating power, but the relay is a normally closed contact. Power is supplied to the drive circuit 14 so that the contact of the relay 14 is opened. Here, the power supplied to the drive circuit of the relay 14 is the power supplied from the power conditioner 3 as described above.

  In connection with this control, the FC control unit 11 is set to open the contact of the normally closed relay 14 at the time of start-up (in the initial initial operation when power is supplied to the FC control unit 11). (Program). That is, when power is supplied to the FC control unit 11, the power generation unit is not generating power, so the FC control unit 11 opens the contact of the relay 14 as an initial operation when the power supply is started. It is like that. Note that the converter and inverter in the power conditioner 3 in a stopped state are in an operation stopped state, and the grid interconnection relay is opened (disconnected).

  When the power generation unit of the fuel cell device 1 starts power generation, the FC control unit 11 transmits a message to start power generation to the PC control unit 31 and closes the switch 12 with the start of power generation. To control. That is, power is also supplied to the drive circuit of the switch 12, and the contact of the switch 12 is closed. At this time, power is continuously supplied to the drive circuit of the relay 14, and the contact of the relay 14 is maintained in an open state (see FIG. 1B).

  As a result, the DC power generated by the power generation unit of the fuel cell device 1 charges the capacitor 32 via the switch 12 and the resistor 13. At this time, since the relay 14 is maintained in the open state, the current output from the power generation unit of the fuel cell device 1 is supplied to the capacitor 32 through the resistor 13 for current limitation. Large inrush current is suppressed (prevents inrush current to the capacitor).

  On the other hand, when the PC control unit 31 of the power conditioner 3 knows that the power generation unit of the fuel cell device 1 starts power generation through communication from the FC control unit 11, it starts the operation of the power conditioner 3 (see FIG. 2 (see step S1), information on the input voltage (voltage value information) measured by the voltage sensor 33 is sequentially transmitted to the FC controller 11. At this time, the voltage sensor 33 does not detect the voltage for a short time immediately after the switch 12 is closed (for example, about several microseconds to several tens of microseconds), but the capacitor 32 is sufficiently charged. Then, the voltage is detected by the voltage sensor 33, and the result is transmitted to the FC control unit 11.

The FC controller 11 monitors the input voltage information of the power conditioner 3 transmitted from the PC controller 31 after the switch 12 is closed, and the input voltage is set to a predetermined voltage ( for example, ○ ○ V ) It is determined whether or not (see Step S2 in FIG. 2), and if there is an input voltage equal to or higher than a predetermined voltage (if Yes in Step S2 in FIG. 2), the contact of the relay 14 is closed ( The contact is turned on) (see FIG. 1C and step S3 in FIG. 2). That is, the FC control unit 11 stops the power supply to the drive circuit of the normally closed contact relay 14 on the condition that the input voltage of the power conditioner 3 is equal to or higher than a predetermined voltage, and closes the contact of the relay 14. .

  Thus, the DC power output from the fuel cell device 1 is supplied to the power conditioner 3 via the relay 14 without passing through the resistor 13. Therefore, after the power generation unit starts power generation and the input voltage of the power conditioner 3 becomes equal to or higher than the predetermined voltage, power is consumed by the resistor 13 as long as power generation in the power generation unit is continued. The electric power generated by the fuel cell device 1 can be supplied to the power conditioner 3 without waste. Moreover, since the power conditioner 3 does not need to supply power to the drive circuit of the relay 14, it can efficiently convert DC power into AC power.

  On the other hand, when the power generation in the power generation unit is stopped, the power conditioner 3 returns to the standby state and is in the state shown in FIG. That is, the FC control unit 11 stops power supply to the drive circuit of the switch 12 to open the contact of the switch 12 and starts supplying power to the drive circuit of the relay 14 that is a normally closed contact. Then, the contact of the relay 14 is opened (see step S4 in FIG. 2).

  Thus, in the power generation system according to the present invention, the contact is closed as the relay 14 that short-circuits the resistor 13 of the inrush current prevention circuit connected to the switch 12 that turns on / off the output of the fuel cell device 1. However, a normally closed contact (b contact) relay that does not consume power is used, so when the power generation unit of the fuel cell device 1 is generating power (that is, when the power conditioner 3 is in operation) No power is consumed by the relay 14 of the current prevention circuit. Therefore, it is not necessary to supply power for operating the relay 14 from the power conditioner 3 while the fuel cell device 1 is generating power. The power generated by the fuel cell device 1 can be converted into AC power without waste. A decrease in the efficiency of the conditioner 3 is prevented. Therefore, when using a power generator in which the standby time of the power conditioner is extremely shorter than the operating time, such as a fuel cell device, the above-described effects of the present invention (the power consumption in the inrush current prevention circuit is small, and the power It is possible to enjoy more of the effect of suppressing the decrease in the efficiency of the conditioner.

  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 embodiment described above, the power condition given from the PC control unit 31 is a condition for closing the contact of the relay 14 of the inrush current prevention circuit (whether the input voltage of the power conditioner 3 is equal to or higher than a predetermined voltage). Although the case where the FC controller 11 side is configured to make a determination based on the voltage value of the input voltage of the na 3 is shown, this determination is performed on the PC controller 31 side, and the result is transmitted to the FC controller 11 You may comprise. In that case, the FC control unit 11 is configured to perform control for closing the relay 14 (stopping power supply to the drive circuit of the relay 14) in accordance with an instruction from the PC control unit 31.

  In the above-described embodiment, the capacitor 32 and the voltage sensor 33 are both provided in the power conditioner 3. However, the capacitor 32 and the voltage sensor 33 may be provided outside the power conditioner 3.

  In the above-described embodiment, the fuel cell is used as the power generation device to which the present invention is applied. However, any power generation device other than the fuel cell (for example, a solar cell) may be used as long as it is a power generation device that generates DC power. The present invention is also applicable to In addition to the solid oxide fuel cell (SOFC), the fuel cell can of course be applied to a fuel cell device including a fuel cell such as a solid polymer fuel cell (PEFC).

  In the above-described embodiment, the case where the normally closed contact relay 14 is set to open the contact in the initial operation of the FC control unit 11 has been described. However, the power consumption in the drive circuit of the relay 14 is reduced. From the viewpoint, when the switch 12 is opened, the relay 14 can be set to be closed. That is, in this case, the FC control unit 11 opens the relay 14 immediately before closing the contact point of the switch 12 by the start of power generation, that is, immediately before supplying power to the drive circuit of the switch 12. It can be set to supply power to the drive circuit to open the relay 14. Thereby, the power consumption in the drive circuit of the relay 14 while the switch 12 is opened (while the power generation unit is not generating power) can be reduced.

DESCRIPTION OF SYMBOLS 1 Fuel cell apparatus 2 Electric power system 3 Power conditioner 11 FC control part (control part)
11a Control board 12 Switch 13 Resistor 14 Normally closed relay 31 PC control unit 32 Capacitor 33 Voltage sensor (voltage measuring means)

Claims (4)

A positive electrode that includes a power generator that generates DC power, and a power conditioner that converts DC power supplied from the power generator into AC power, and connects an output unit of the power generator and an input unit of the power conditioner. In a power generation system with a capacitor between the negative and negative lines,
A normally closed contact relay that short-circuits the resistor at both ends of the resistor is connected to a line upstream of the capacitor in series with a switch for turning on / off the output of the power generator and a resistor. Is connected,
The control unit is set to open the contact of the relay of the normally closed contact at the time of starting, and performs control to close the switch when supplying the output of the power generator to the power conditioner. After that, the power generation system has a control configuration for performing control to close the relay of the normally closed contact on condition that the input voltage of the power conditioner becomes equal to or higher than a predetermined voltage.   2. The power generation system according to claim 1, wherein the control unit, the switch, the resistor, and the relay of the normally closed contact are all provided in the power generation device.   The power generation system according to claim 1, wherein the switch includes a normally open contact relay.   The power conditioner includes voltage measuring means for measuring an input voltage from the power generator, and information on the input voltage of the power conditioner measured by the voltage measuring means is passed through the control section of the power conditioner. The power generation system according to claim 2 or 3, wherein the power generation system is configured to be transmitted to the control unit provided in the power generation device.

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