JP2012249486A - Power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation system capable of efficiently supplying generated power to an auxiliary machine without causing deterioration of a fuel cell.SOLUTION: In a power generation system 1 comprising a fuel cell device 2, when supplying power from a power generation part 5 to an auxiliary machine power supply part 7 which supplies power to an auxiliary machine of a fuel cell, a current sensor 13 is provided to detect current amount (supplied current amount) supplied from the power generation part 5 to the auxiliary machine power supply part 7. Then, when a control part 8 of the fuel cell device 2 gives a control target value that controls input current of a converter 16 to a control part 19 of a power conditioner 4, a value calculated by subtracting supplied power amount detected by the current sensor 13 from power generated amount by the power generation part 5 is given to the control part 19 of the power conditioner 4 as the control target value.

Description

  The present invention relates to a power generation system, and more particularly, to a power supply technique for an auxiliary machine of a fuel cell in a power generation system including a fuel cell as a power generation unit.

  Recently, a power generation system using a combination of power generation by a fuel cell (fuel cell power generation) and power generation by a solar cell (solar power generation) has been provided in a household power generation system.

  In this type of power generation system, a power conditioner, which is an inverter device that converts DC power into AC power, is used so that the DC power generated by a fuel cell or solar cell can be used in a household load (power load). However, in the conventional power generation system, as shown in FIG. 2, since the power conditioner c is connected to each of the solar cell a and the fuel cell b (two power conditioners were used). Therefore, in the two power conditioners c and c, there is a waste that an inverter e and a display unit f having substantially the same functions are provided in an overlapping manner.

  Therefore, recently, in order to eliminate such a waste in the configuration, as shown in FIG. 3A, a single power conditioner g is configured to be shared by the solar cell a and the fuel cell b. A power generation system has been proposed (see, for example, Patent Document 1 and Patent Document 2).

That is, in the power generation system shown in FIG. 3 (a), the power conditioner g, provided a converter d _b for converter d _a fuel cell for solar cells, these converters d _a, boosted by d _b One inverter e is shared as an inverter for converting DC power into AC power, and one display unit f shared for solar cell power generation and fuel cell power generation is used for the display unit.

JP 2002-136112 A Japanese Patent Laid-Open No. 2005-151662

  By the way, under the idea that the solar cell power generation and the fuel cell power generation share the inverter in this way, the power supply to the auxiliary device (not shown) of the fuel cell b is, for example, as shown in FIG. As described above, it is conceivable to perform the operation via the outlet i connected to the system (commercial power supply). In this case, the fuel cell b is provided with an auxiliary power source h provided with an AC / DC converter, and AC power is supplied to the auxiliary power source h via the outlet i. That is, when the fuel cell b is not generating power, AC power from the commercial power source is supplied to the auxiliary power source h. When the fuel cell b is generating power, as shown in FIG. The AC power generated by the fuel cell b and converted into AC by the inverter e is supplied to the auxiliary power source h. In any case, the AC / DC converter of the auxiliary power source h converts the DC power into DC power. Configured to supply power.

  However, in such a configuration, when the fuel cell b is generating power, the power is supplied to the auxiliary equipment by once converting the power converted into the alternating current by the inverter e to the direct current by the auxiliary power supply h. Therefore, there is a problem that power generation efficiency is reduced due to a loss due to conversion from direct current to alternating current.

  Therefore, for the purpose of reducing such conversion loss, the applicant converts the DC power output from the power generation unit k of the fuel cell b to the auxiliary machine power source h into the DC voltage for the auxiliary machine as shown in FIG. When the fuel cell b is not generating power, the AC power from the commercial power source is supplied to the AC / DC converter of the auxiliary power source h, while the fuel cell b is mounted. When b is generating power, it is considered that the DC power generated by the fuel cell b is directly supplied to the DC / DC converter of the auxiliary power source h.

However, in such a configuration, as shown in FIG. 4B, a part of the current generated by the power generation unit k of the fuel cell b flows to the auxiliary power source h. employing converter for inputting current control converter d _b for a battery, only the current component flowing through the auxiliary power source h will be extra current is consumed, consumed by the power conditioner g an auxiliary power supply h The amount of current (the amount of current consumed) will exceed the amount of power generation current generated by the power generation unit k. In other words, the power generation current is smaller than the current consumption, which causes the power generation unit k of the fuel cell b to deteriorate.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a power generation system that can efficiently supply generated power to an auxiliary machine without causing deterioration of the fuel cell. It is to provide.

  In order to achieve the above object, a power generation system according to claim 1 of the present invention includes a fuel cell device having a fuel cell as a power generation unit, and AC power generated by the power generation unit that can be connected to a system. A power generation system including a power conditioner for conversion, wherein the fuel cell device includes an auxiliary power supply unit that supplies electric power to the auxiliary machine, and the auxiliary power supply unit directly generates electric power from the power generation output of the power generation unit. A device configured to receive the supply includes a current detection unit that detects a supply current amount from the power generation unit to the auxiliary power supply unit, and the control unit includes the power generation current amount of the power generation unit and the current detection unit. The difference between the amount of current supplied to the auxiliary power supply unit detected by the means is calculated, and the input current control of the power conditioner is performed using the calculated result as the input current control value.

  In the power generation system according to claim 1, when the power can be directly supplied from the power generation unit of the fuel cell device to the auxiliary power supply unit of the fuel cell device, the power supply unit supplies the power to the auxiliary power unit. Current detection means for detecting the amount of current (amount of supply current) is provided to detect the amount of current flowing through the auxiliary power supply when the power generation unit of the fuel cell device is generating power. When the input current control of the converter in the power conditioner is performed, the control unit obtains the difference between the amount of current generated by the power generation unit (the amount of generated current) and the amount of supplied current from the fuel cell device. The amount of current supplied to the converter is obtained, and this amount of current is used as a control target value (input current control value) for input current control of the converter. Therefore, in the power generation system according to claim 1, even if a part of the generated current generated by the power generation unit of the fuel cell device is supplied to the auxiliary power supply unit, the consumption consumed by the power conditioner It is avoided that the amount of current exceeds the amount of generated current, and deterioration of the power generation unit of the fuel cell device is prevented. That is, the generated power can be efficiently supplied to the auxiliary machine without causing deterioration of the power generation unit.

  In the power generation system according to claim 2 of the present invention, in the power generation system according to claim 1, the control unit includes a control unit of a fuel cell device and a control unit of a power conditioner, The control unit of the fuel cell calculates the input current control value and transmits the result to the control unit of the power conditioner. The control unit of the power conditioner controls the power conditioner based on the received input current control value. It is comprised so that it may control.

  In the power generation system according to the second aspect, the control unit of the fuel cell device and the control unit of the power conditioner are used as the control unit of the power generation system. Then, calculation of the control target value (input current control value) of the input current control performed by the power conditioner described above is performed by the control unit on the fuel cell device side, and the calculation result is transmitted to the control unit of the power conditioner. I have to. For this reason, a value obtained by subtracting the amount of supply current flowing to the auxiliary power supply unit from the amount of generated current of the power generation unit is given to the control unit of the power conditioner as a control target value for input current control. A configuration in which the power generated by the power generation unit is supplied to the auxiliary power supply unit without any change to the configuration on the na side can be adopted.

  According to the present invention, the power generation system includes the current detection means for detecting the amount of current supplied from the power generation unit of the fuel cell device to the auxiliary power supply unit, and the control unit detects the power generation current amount and the current detection of the power generation unit of the fuel cell device. The power generator is controlled by calculating the difference between the amount of current supplied to the auxiliary power supply detected by the means and using the calculation result as the control value for the input current control in the power conditioner. Even if it is configured to supply a part of the generated current generated at the power source to the auxiliary power unit, the amount of current consumed by the power conditioner does not exceed the amount of generated current at the power generator. Deterioration of the power generation unit is prevented.

1 shows an example of a schematic configuration of a power generation system according to the present invention, FIG. 1 (a) is a circuit block diagram of the power generation system, and FIG. 1 (b) is for an auxiliary power supply unit and a power conditioner in the power generation system. It is explanatory drawing which shows an electric power supply path | route. It is a block diagram which shows schematic structure of an example of the conventional electric power generation system. Fig. 3 shows a schematic configuration of another example of a conventional power generation system, in which Fig. 3 (a) is a circuit block diagram of the power generation system, and Fig. 3 (b) is an auxiliary power supply during fuel cell power generation in the power generation system. It is explanatory drawing which shows the electric power supply path | route with respect to a part. FIG. 4A shows a modified example of the power generation system shown in FIG. 3, FIG. 4A is a circuit block diagram of the power generation system, and FIG. 4B is a power supply to an auxiliary power supply unit and a power conditioner in the power generation system. It is explanatory drawing which shows a path | route.

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 to which the present invention is applied. This power generation system 1 is a household power generation system having a fuel cell and a solar cell as a power generation unit, and as shown in FIG. As the main part.

  The fuel cell device 2 supplies a fuel gas containing hydrogen such as natural gas and an oxidant gas containing oxygen such as air, and a power generation unit (fuel cell) 5 that obtains DC power by chemically reacting hydrogen and oxygen. Of auxiliary equipment 6 (see FIG. 1 (b)) including peripheral equipment of the power generation section 5, an auxiliary power supply section 7 for supplying power to the auxiliary equipment 6, and a fuel cell device 2 A control unit (hereinafter referred to as “FC control unit”) 8 that controls each unit is provided as a main unit.

  Here, as the power generation unit 5, for example, a fuel cell having a known configuration such as a solid oxide fuel cell (SOFC) or a polymer electrolyte fuel cell (PEFC) is used. Further, the auxiliary machine is housed in the casing (not shown) of the fuel cell device 2 together with the power generation unit 5 and the like, and a blower, a pump, and the like that consume electric power when the power generation unit 5 is prepared for start-up or during power generation operation. It consists of a power load.

  The auxiliary machine power supply unit 7 receives direct current power supplied to the auxiliary machine 6 from AC power supplied from the system A such as a commercial power supply or direct current power supplied from the power generation unit 5 without going through the power conditioner 4. An AC / DC converter 9 that converts AC power into DC power of a desired voltage (for example, DC 24 V) and DC power converted to DC power of a desired voltage (for example, DC 24 V) And a DC / DC converter 10 (see FIG. 1B).

  As shown in FIG. 1B, the AC / DC converter 9 of the auxiliary power unit 7 has a system A (specifically, a distribution board (not shown) that receives AC power supplied from the system A) and a power source on its input side. They are connected via a line 11. The DC / DC converter 10 of the auxiliary machine power supply unit 7 is connected at its input side to the power generation unit 5 via the power line 12, and a part of the DC power generated by the power generation unit 5 is the DC / DC. It is configured to be supplied to the DC converter 10.

  In the present invention, the power supply line 12 is provided with a current sensor (current detection means) 13 so that the amount of current (supply current amount) supplied from the power generation unit 5 to the auxiliary power supply unit 7 can be detected. It is configured.

  The FC control unit 8 is a control device that controls the operation of each unit of the fuel cell device 2, and includes a microcomputer (not shown) as a control center. The FC control unit 8 is electrically connected to various sensors (for example, the current sensor 13) provided in each unit of the fuel cell device 2, acquires information obtained by these sensors, and power condition described later. Is connected to the control unit 19 of the power conditioner 4 and exchanges control information with the control unit 19 of the power conditioner 4, and performs various controls such as power generation control of the power generation unit 5 and power source switching control of the auxiliary power source unit 7. Configured to do. In FIG. 1, reference numeral 14 indicates an electrical line for connection with the current sensor 13, and reference numeral 15 indicates a communication line with the control unit 19 of the power conditioner 4.

  Here, the power generation control of the power generation unit 5 by the FC control unit 8 is performed based on the information regarding the purchased power from the system A given from the control unit 19 of the power conditioner 4. That is, in this power generation control, the FC control unit 8 reduces the purchased power from the system A and the power generation unit 5 so that the power generated by the power generation unit 5 is consumed by the power conditioner 4 without waste. The amount of power generation is controlled.

  Specifically, when the purchased power from the system A increases and the purchased power exceeds a predetermined threshold (purchased power> threshold), the FC control unit 8 increases the generated power in the power generation unit 5. Then, when the generated power in the power generation unit 5 increases, the purchased power decreases (purchased power≈0), and the input current control value of the power conditioner 4 approximates the actual input current ( When the input current control value≈the input current value), the generated power in the power generation unit 5 is maintained as it is, while the purchased power is low (purchased power≈0) and the input of the power conditioner 4 When the control value of the current control becomes larger than the actual input current (when the input current control value> the input current value), the generated power in the power generation unit 5 is reduced. Note that such control of generated power is performed by the FC control unit 8 controlling the supply amounts of fuel gas and oxidant gas supplied to the power generation unit 5.

  In relation to this power generation control, the FC control unit 8 controls the power conditioner 4 based on the power generation current in the power generation unit 5 to control the input current of the converter 16 (input current). Control value) is transmitted (details will be described later).

  On the other hand, as is well known, the solar cell panel 3 is a power generation facility in which a plurality of solar cells are connected and arranged in a panel shape, and is configured to convert sunlight energy into DC power.

  The power conditioner 4 is an inverter device that converts direct current power generated by the fuel cell device 2 and the solar cell panel 3 into alternating current power that can be connected to the system A. As shown in FIG. A converter 16 for the device 2, a converter 17 for the solar battery panel 3, an inverter 18 shared by the converters 16 and 17, and a controller that controls each part of the power conditioner 4 (hereinafter referred to as "PC controller"). 19) as a main part.

  The converters 16 and 17 are supplied from the power generation unit 5 and the solar cell panel 3 of the fuel cell device 2 so that the inverter 18 can generate AC power having a voltage (for example, AC 200 V) that can be linked to the system A. It is composed of a DC-DC converter that boosts DC power. The specific configuration and control of each converter 16, 17 is determined according to the characteristics of the power generation equipment connected to each converter 16, 17. In this embodiment, the power generation unit (fuel) of the fuel cell device 2 is determined. The converter 16 to which the battery (5) is connected is an insulating type and an input current controlled converter. On the other hand, the converter 17 to which the solar cell panel 3 is connected is a non-insulating or insulating converter that uses maximum power point tracking control (MPPT control).

  The converters 16 and 17 are connected at the connection point 20 so that the boosted DC power is supplied to the inverter 18, and the connection point 20 is connected to the DC link portion (see FIG. (Not shown).

  The inverter 18 is configured by a DC-AC inverter that converts the DC power boosted by the converters 16 and 17 into voltage / frequency AC power (for example, single-phase three-wire 200V) that can be linked to the system A. The inverter 18 is controlled so that the voltage of the DC link unit becomes constant.

  The PC control unit 19 is a control device that controls the operation of each unit of the power conditioner 4 and includes a microcomputer (not shown) as a control center. And this PC control part 19 is based on the information obtained by the various sensors with which each part of the power conditioner 4 is provided, the control information obtained from the said FC control part 8, etc., such as converters 16 and 17 and inverter 18 It is configured to perform control.

  Specifically, for example, the PC control unit 19 controls the input current of the converter 16 based on the input current control value (control target value) given from the FC control unit 8 regarding the control of the converter 16. . Further, in relation to the power generation control in the FC control unit 8, the purchased power from the system A is calculated based on information obtained from various sensors, and the result is transmitted to the FC control unit 8.

  Therefore, in the power generation system 1 configured as described above, when at least one of the power generation unit 5 of the fuel cell device 2 or the solar cell panel 3 starts power generation, the PC control unit 19 generates power generation. The converters 16 and 17 to which the power generation equipment that started the operation is connected are operated and the inverter 18 is operated to convert the DC power output from the converters 16 and 17 into AC power by the inverter 18 and connect to the system A. It is designed to be related.

Then, next, characteristic operation | movement of the electric power generation system 1 which concerns on this invention is demonstrated.
A: Power Supply Switching Control of Auxiliary Power Supply Unit 7 As described above, in the power generation system 1 according to the present invention, the auxiliary power supply unit 7 includes the AC / DC converter 9 that receives AC power supplied from the system A, the fuel The DC / DC converter 10 that receives the DC power from the power generation unit 5 of the battery device 2 is provided. The power supply to the auxiliary machine 6 is either the AC / DC converter 9 or the DC / DC converter 10. The FC control unit 8 is configured to perform the switching control (power switching control).

  Specifically, when the power generation unit 5 is in a power generation stop state (including preparation for starting until the power generation unit 5 starts power generation normally), the FC control unit 8 The AC / DC converter 9 is operated (at this time, the operation of the DC / DC converter 10 is stopped), and the AC power supplied from the system A is converted into DC power of a desired voltage by the AC / DC converter 9 to compensate. Power is supplied to the machine 6. That is, since the power cannot be supplied from the power generation unit 5 to the auxiliary machine 6 when the power generation unit 5 is not generating power, in this case, the auxiliary machine 6 can be operated using the power supplied from the system A. Keep it in a proper state.

  When the power generation unit 5 is in a power generation state (when the power generation unit 5 is generating power normally), the FC control unit 8 operates the DC / DC converter 10 and also the AC / DC converter. 9 is stopped, and the DC power generated by the power generation unit 5 is converted into a DC output of a desired voltage by the DC / DC converter 10 and supplied to the auxiliary machine 6. That is, after the power generation unit 5 starts power generation, the auxiliary machine 6 is operated using the DC power generated by the power generation unit 5.

  As described above, in the power generation system 1 of the present invention, when the power generation unit 5 of the fuel cell device 2 is generating power, the power generated by the power generation unit 5 is used as power for operating the auxiliary machine 6. Power consumption can be suppressed. In addition, the power supplied to the auxiliary machine 6 at this time is directly supplied from the power generation unit 5 to the auxiliary power supply unit 7 without once converting the power generated by the power generation unit 5 into AC power by the power conditioner 4. Therefore, there is no conversion loss due to conversion from direct current to alternating current, and power can be supplied to the auxiliary machine 6 without causing a decrease in power generation efficiency.

B: Calculation of Input Current Control Value (Control Target Value) of Converter 16 As described above, the converter 16 to which the fuel cell device 2 is connected is based on the input current control value transmitted from the FC control unit 8. In this case, if the generated current value of the power generation unit 5 is directly supplied to the PC control unit 19 as an input current control value (control target value), the power generation unit 5 compensates during power generation. In the power generation system 1 of the present invention configured to supply a part of the generated current to the machine power supply unit 7, the amount of current (consumed current amount) consumed by the power conditioner 4 and the auxiliary power supply unit 7 is generated. There is a possibility that the power generation unit 5 may be deteriorated by exceeding the amount of current generated by the unit 5.

  Therefore, in the power generation system 1 according to the present invention, in the FC control unit 8 that determines the input current control value of the converter 16, the current sensor 13 determines the amount of generated current from the power generation unit 5 so that such a situation does not occur. The detected supply current amount to the auxiliary machine power supply unit 7 is subtracted (the difference between the generated current amount and the supply current amount to the auxiliary machine power supply unit 7 is calculated), and the result is input current control value of the converter 16. Is transmitted to the power conditioner 4.

  Thus, in the power generation system 1 of the present invention, when setting the control target value for the input current control of the converter 16, the difference between the power generation current amount of the power generation unit 5 and the supply current amount to the auxiliary power supply unit 7 is obtained. As a result, the current value actually supplied to the power conditioner 4 can be set as the control target value, so that the current consumption amount consumed by the power conditioner 4 and the auxiliary machine 6 exceeds the power generation current amount of the power generation unit 5. This prevents the power generation unit 5 from deteriorating. Therefore, in the power generation system of the present invention, a power generation system capable of efficiently supplying the generated power to the auxiliary device 6 while preventing the power generation unit 5 from being deteriorated, coupled with the power source switching control of the auxiliary power source unit 7 described above. Will be able to provide.

  Moreover, in the power generation system 1 of the present invention, the calculation of the control target value (input current control value) of the input current control of the converter 16 performed by the power conditioner 4 is performed by the FC control unit 8 on the fuel cell device 2 side, and the power Since the calculation result is transmitted to the PC control unit 19 of the conditioner 4, the power generated by the power generation unit 5 is supplied to the auxiliary power supply unit 7 without any change in the configuration of the power conditioner 4. The present invention to be supplied can be applied. That is, the present invention can be applied to an existing power generation system only by replacing the fuel cell device 2.

  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, the case where the fuel cell device 2 and the solar cell panel 3 are used as the power generation equipment connected to the power conditioner 4 is shown. However, the power generation system 1 according to the present invention is configured from the power generation unit 5. Since it is applied to a power generation system that includes a fuel cell device 2 including an auxiliary power supply unit 6 that can receive direct power supply as a power generation facility, another power generation facility is attached to the fuel cell device 2. It does not have to be. Moreover, it may replace with the solar cell panel 3, and the structure which arrange | positions another DC power generation equipment may be sufficient.

  In the above-described embodiment, the case where the calculation of the input current control value (control target value) of the converter 16 is performed by the FC control unit 8 on the fuel cell device 2 side is shown. The amount of current and the amount of current supplied to the auxiliary power unit 7 detected by the current sensor 13 are transmitted to the PC control unit 19 of the power conditioner 4, and the PC control unit 19 controls the input current of the converter 16 based on these. It can also be configured to compute values. Further, the detection result of the current sensor 13 is configured to be transmitted to the PC control unit 19 without going through the FC control unit 8, and the amount of generated current is transmitted from the FC control unit 8, and based on these, the PC control unit 19 is transmitted. The control target value (input current control value) of the input current control described above can be calculated.

  Further, in the above-described embodiment, the case where the control unit of the power generation system 1 includes the FC control unit 8 of the fuel cell device 2 and the PC control unit 19 of the power conditioner 4 has been described. A control unit in which the control units 8 and 19 are integrated may be provided in the fuel cell device 2 or the power conditioner 4, or a control device independent of these may be provided.

DESCRIPTION OF SYMBOLS 1 Power generation system 2 Fuel cell apparatus 3 Solar cell panel 4 Power conditioner 5 Power generation part (fuel cell)
6 Auxiliary machine 7 Auxiliary machine power supply unit 8 FC control unit (control unit of fuel cell system)
9 AC / DC converter 10 DC / DC converter 13 Current sensor (current detection means)
16, 17 Converter 18 Inverter 19 PC control unit (control unit of power conditioner)

Claims (2)

A power generation system comprising: a fuel cell device having a fuel cell as a power generation unit; and a power conditioner that converts electric power generated by the power generation unit into AC power that can be connected to a system. In addition to the auxiliary power supply that supplies power to the auxiliary machine, the auxiliary power supply is configured to receive power directly from the power generation output of the power generation unit.
Comprising current detection means for detecting the amount of current supplied from the power generation unit to the auxiliary power supply unit;
The control unit calculates a difference between the amount of generated current of the power generation unit and the amount of current supplied to the auxiliary power supply unit detected by the current detection means, and uses the calculation result as an input current control value as a power conditioner. A power generation system characterized by performing input current control. The control unit is composed of a fuel cell device control unit and a power conditioner control unit,
The control unit of the fuel cell calculates the input current control value and transmits the result to the control unit of the power conditioner, and the control unit of the power conditioner controls the power based on the received input current control value. The power generation system according to claim 1, wherein the power generation system is configured to control the conditioner.

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