JP3939978B2 - Fuel cell power generation system and operation method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell power generation system and an operation method thereof, and more specifically, a fuel cell power generation system capable of supplying output power derived from a fuel cell to a power supply line that supplies power from another system power source to a load, and an operation method thereof. About.
[0002]
[Prior art]
In recent years, a power generation system incorporating a fuel cell has been proposed as a cogeneration system in consideration of environmental problems. In addition, a fuel cell includes a single electrode comprising an electrolyte membrane, an anode electrode and a cathode electrode that sandwich the electrolyte membrane, and a separator that supplies fuel gas and air to the anode electrode and the cathode electrode and forms a partition between cells. 2. Description of the Related Art A solid polymer electrolyte type fuel cell in which a plurality of cells are stacked is known. As an operation control of such a solid polymer electrolyte type fuel cell, Japanese Patent Application Laid-Open No. 7-272736 discloses an output voltage of a fuel cell which is monitored when output power from the fuel cell is supplied to a load. A control is disclosed that cuts off the current applied to the load when the voltage is abnormally low.
[0003]
[Problems to be solved by the invention]
However, in the operation control of the fuel cell described in the above-mentioned publication, the current applied to the load is cut off when the output voltage of the fuel cell is abnormally low, which may hinder the operation status of the cogeneration system. is there.
[0004]
The present invention has been made in view of the above-described problems, and provides a fuel cell power generation system and a method for operating the fuel cell power generation system that can cope with the operation state without greatly affecting the operation state when the output voltage of the fuel cell drops. For the purpose.
[0005]
[Means for solving the problems and their functions and effects]
  In order to achieve the above-described object, a first aspect of the present invention is a fuel cell power generation system capable of supplying output power derived from a fuel cell to a power supply line that supplies power from another system power supply to a load,
  Voltage detection means for detecting the output voltage of the fuel cell;
  Power control means for controlling the output power derived from the fuel cell to be a predetermined target power value;
  Voltage drop determination means for determining whether or not the output voltage of the fuel cell has dropped when the output power derived from the fuel cell is controlled to the target power value;
  With
  When the power control means determines that the output voltage of the fuel cell has dropped by the voltage drop determination means,The output power derived from the fuel cell is controlled to be a provisional power value lower than the target power value, and the output power derived from the fuel cell is stabilized at the provisional power value and then derived from the fuel cell. A means for controlling the output power to substantially match the original target power value;
The provisional power value is determined in a stepwise manner such that the provisional power value becomes lower as the drop width of the output voltage of the fuel cell is larger.Is.
[0006]
  In this fuel cell power generation system, it is determined whether or not the output voltage of the fuel cell has dropped when the output power derived from the fuel cell is controlled to be a predetermined target power value, and the output voltage of the fuel cell is determined. When it is determined that the output voltage of the fuel cell has decreased, the output power derived from the fuel cell is controlled to be a provisional power value lower than the target power value until the output voltage of the fuel cell becomes stable. That is, since a drop in the output voltage of the fuel cell is often seen temporarily, the output power of the fuel cell is temporarily lowered to wait for the output voltage of the fuel cell to stabilize. Therefore, according to this fuel cell power generation system, when the output voltage of the fuel cell drops, it is possible to cope with it without greatly affecting the operation state.Further, since the provisional power value is determined in a stepwise manner according to the drop width of the output voltage of the fuel cell, an appropriate provisional power value can be determined according to the drop width of the output voltage. The provisional power value is determined so as to decrease as the output voltage drop of the fuel cell increases. Since the output voltage of the fuel cell tends to be difficult to stabilize when the drop width is large, the provisional power value is lowered to stabilize the output voltage of the fuel cell as soon as possible. Since the tendency tends to be stable, the provisional power value is set to a value close to the target power value and returned to the original target power value as soon as possible. Note that the drop width of the output voltage of the fuel cell is, for example, when determining whether or not the output voltage of the fuel cell has dropped by the voltage drop degree that is the difference between the reference voltage value and the output voltage. In the case of determining by the time differential value of the output voltage, it is the size of the time differential value.
[0007]
The “output voltage of the fuel cell” may be a stack voltage (voltage between current collector plates sandwiching a plurality of single cells) in the case of a fuel cell in which a plurality of single cells are stacked, It may be a cell voltage for each cell.
[0008]
  In this fuel cell power generation system, the power control means controls the output power derived from the fuel cell to be a provisional power value lower than the target power value, thereby stabilizing the output voltage of the fuel cell. , Output power derived from the fuel cellStep by step in small incrementsBy increasing the value, it may be made to substantially match the original target power value. In this way, even if there is a response delay in increasing the fuel gas supply amount of the fuel cell, the output power derived from the fuel cell can be smoothly returned to the original target power value. In particular, when the fuel cell receives a supply of fuel gas from a reforming unit that reforms a hydrocarbon-based fuel into a hydrogen-rich fuel gas, the hydrocarbon-based fuel to the reforming unit is increased in order to increase the supply amount of the fuel gas. Therefore, it is important to gradually increase the output power derived from the fuel cell and return it to the original target power value.
[0009]
In this fuel cell power generation system, the voltage drop determination means is configured such that the output voltage of the fuel cell is a predetermined reference voltage when the output power derived from the fuel cell is controlled to the target power value by the power control means. It may be determined whether or not the output voltage of the fuel cell has dropped depending on whether or not it has become smaller than the value. In this way, it is possible to easily determine whether or not the output voltage has dropped by comparing the output voltage of the fuel cell with a predetermined reference voltage value. At this time, since the output characteristics of fuel cells often change depending on operating conditions such as temperature, it is preferable to set a reference voltage value for each operating condition of the fuel cell. The work of setting is complicated. Therefore, the reference voltage value is preferably the output voltage of the fuel cell that is stable when the output power derived from the fuel cell is controlled to the target power value by the power control means. By so doing, it is possible to easily set an optimal reference voltage value under the operating conditions at that time, and therefore it is possible to appropriately determine whether or not the output voltage of the fuel cell has dropped.
[0010]
In this fuel cell power generation system, the voltage drop determination means has a time differential value of the output voltage of the fuel cell when the output power derived from the fuel cell is controlled to the target power value by the power control means. It may be determined whether or not the output voltage of the fuel cell has dropped depending on whether or not it has become smaller than a predetermined threshold value. In this way, since it is determined whether or not the output voltage of the fuel cell has dropped according to the time variation of the output voltage of the fuel cell, it can be grasped relatively quickly that the output voltage of the fuel cell has dropped. .
[0012]
The fuel cell power generation system includes power conversion means for converting DC power from the fuel cell into desired power to be supplied to the power supply line, and output power derived from the fuel cell is converted by the power conversion means. It is good also as electric power after being done. If it carries out like this, electric power (for example, alternating current power) after being changed by the power conversion means can be controlled so that it may become a target electric power value.
[0013]
  A second aspect of the present invention is a method of operating a fuel cell power generation system capable of supplying output power derived from a fuel cell to a power supply line that supplies power from another system power supply to a load,
  When the output power derived from the fuel cell is controlled to be a predetermined target power value, it is determined whether the output voltage of the fuel cell has dropped, and the output voltage of the fuel cell has dropped When judgedThe output power derived from the fuel cell is controlled to be a provisional power value lower than the target power value, and the output power derived from the fuel cell is stabilized at the provisional power value and then derived from the fuel cell. The output power is controlled so as to substantially match the original target power value, and the provisional power value is determined in stages so as to decrease as the output voltage drop of the fuel cell increases.Is. According to the operation method of the fuel cell power generation system, when the output voltage of the fuel cell drops, it is possible to cope with it without greatly affecting the operation state.
[0014]
  In the operation method of the fuel cell power generation system, after the output voltage of the fuel cell is stabilized by controlling the output power derived from the fuel cell to be a provisional power value lower than the target power value, the fuel cell Output power derived from the batteryStep by step in small incrementsBy increasing the value, it may be made to substantially match the original target power value. In this way, for example, even when there is a response delay in increasing the fuel gas supply amount of the fuel cell, the output power derived from the fuel cell can be smoothly returned to the original target power value. it can.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of the configuration of the fuel cell power generation system 20. As shown in the figure, the fuel cell power generation system 20 includes a reformer 30 that receives supply of city gas (13A) from a gas pipe 22 to reform the city gas into a hydrogen-rich reformed gas, CO selective oxidation unit 34 that reduces carbon monoxide to a fuel gas, fuel cell 40 that receives supply of the fuel gas and air and generates electric power through an electrochemical reaction, cooling water and hot water storage tank 44 of the fuel cell 40 A heat exchanger 42 that exchanges heat with low-temperature water, a DC / DC converter 52 that adjusts the voltage and current of DC power from the fuel cell 40 to convert it to desired DC power, and the converted DC power An inverter 54 that supplies power through the circuit breaker 55 to the power line 12 that converts the AC power into the same phase as that of the commercial power supply 10 and supplies power from the commercial power supply 10 to the load 16 through the circuit breaker 14. Adjusted A DC / DC converter 56 that functions as an auxiliary power source by stepping down a part of the direct current power, a load power meter 58 that detects load power consumed by the load 16, and an electronic control unit 60 that controls the entire system. Prepare.
[0016]
The reformer 30 has the following equation (1) based on city gas supplied from the gas pipe 22 through the control valve 24, the booster pump 26, and the desulfurizer 27 excluding sulfur, and water vapor supplied through a pipe (not shown). And the hydrogen-rich reformed gas is generated by the steam reforming reaction and shift reaction of the following formula (2). The reformer 30 is provided with a combustion section 32 that supplies heat necessary for such a reaction. The combustion section 32 is supplied with city gas from a gas pipe 22 through a control valve 24 and a booster pump 28. It has become so. Further, exhaust gas (anode offgas) on the anode side of the fuel cell 40 is supplied to the combustion unit 32 so that unreacted hydrogen in the anode offgas can be used as fuel.
[0017]
[Expression 1]
CH_Four+ H₂O → CO + 3H₂    (1)
CO + H₂O → CO₂+ H₂      (2)
[0018]
The CO selective oxidation unit 34 is modified by a carbon monoxide selective oxidation catalyst (for example, a catalyst made of an alloy of platinum and ruthenium) that receives supply of air from a pipe (not shown) and selects and oxidizes carbon monoxide in the presence of hydrogen. Carbon monoxide in the gas is selectively oxidized to obtain a hydrogen-rich fuel gas having a very low carbon monoxide concentration (about several ppm in this embodiment).
[0019]
The fuel cell 40 includes a single cell composed of an electrolyte membrane, an anode electrode and a cathode electrode that sandwich the electrolyte membrane, a fuel gas and air to the anode electrode and the cathode electrode, and a separator that forms a partition between the cells. It is configured as a solid polymer fuel cell formed by stacking a plurality of layers, and generates power by an electrochemical reaction between hydrogen in the fuel gas from the CO selective oxidation unit 34 and oxygen in the air from the blower 41. The fuel cell 40 includes a pair of current collector plates that sandwich a plurality of stacked single cells, and includes a voltmeter 51 that detects a DC voltage between the current collector plates. The fuel cell 40 is formed with a circulating cooling water passage, and is maintained at an appropriate temperature (in this embodiment, about 80 to 90 ° C.) by circulating the cooling water. A heat exchanger 42 is provided in the cooling water circulation flow path, and the low temperature water supplied from the hot water storage tank 44 by the pump 46 is heated by heat exchange with the cooling water of the fuel cell 40 so that the hot water storage tank. The hot water is stored in 44.
[0020]
An output terminal (not shown) of the fuel cell 40 is connected to the power line 12 from the commercial power supply 10 to the load 16 via the DC / DC converter 52, the inverter 54, and the circuit breaker 55. The AC power is converted into AC power having the same phase as that of the commercial power supply 10, added to the AC power from the commercial power supply 10, and supplied to the load 16. Since the DC / DC converter 52 and the inverter 54 are configured as a general DC / DC / converter circuit and an inverter circuit, detailed description thereof is omitted. The load 16 is connected to the power line 12 via the circuit breaker 18.
[0021]
The power line branched from the output side of the DC / DC converter 52 has a DC / DC functioning as a direct current power source for supplying direct current power to the actuators of the control valve 24 and auxiliary devices such as the boost pumps 26 and 28, the blower 41 and the pump 46. A DC converter 56 is connected.
[0022]
The electronic control unit 60 is configured as a microprocessor centered on the CPU 62. In addition to the CPU 62, a ROM 64 that stores a processing program, a RAM 66 that temporarily stores data, a timer 68 that measures time, An input / output port and a communication port (not shown) are provided. The electronic control unit 60 includes an output voltage Vfc of the fuel cell 40 from the voltmeter 51, an output current and voltage from a current sensor and voltage sensor (not shown), a load power Po from the load wattmeter 58, and reforming. Each temperature from a temperature sensor (not shown) attached to the vessel 30, the CO selective oxidation unit 34, and the fuel cell 40 is input via an input port. Further, the electronic control unit 60 provides a drive signal to the actuator of the control valve 24, boost pumps 26, 28, blower 41, circulation pump 43, pump 46, ignition signal to the combustion section 32, DC / DC converter 52, A control signal to the DC / DC converter 56, a switching control signal to the inverter 54, a drive signal to the circuit breaker 55, and the like are output via the output port.
[0023]
Next, the operation of the fuel cell power generation system 20 configured as described above will be described. FIG. 2 is a flowchart showing an example of a constant power control program, and FIG. 3 is a flowchart showing an example of a voltage drop countermeasure program interrupted at a predetermined timing (for example, every 8 msec).
[0024]
The constant power control program is recorded in the ROM 64 of the electronic control unit 60. When the electronic control unit 60 finishes warming up and moves to normal operation, the electronic control unit 60 reads this constant power control program from the ROM 64 and executes it as the main process. When the process of the constant power control program is started, the CPU 62 of the electronic control unit 60 first reads the operation mode (step S100). As the operation mode, three modes of High mode, Mid mode, and Low mode are prepared, and electric power f (M) output from the inverter 54 to the power line 12 corresponding to each mode (= Pior or Pim or Pil) ) Is set. The operation mode is determined based on a determination result as to which operation mode Mp the load power Po belongs to. The operation mode Mp to which the load power Po belongs is determined by comparing the load power Po with the power f (M) set corresponding to each mode. Specifically, the load power Po corresponds to the High mode. When the load power Po is less than the power Pim, the high mode is determined. When the load power Po is equal to or higher than the power Pim corresponding to the Mid mode and less than the power Pih, the Mid mode is determined. When the load power Po is less than the power Pim, the Low mode is selected. The operation mode M is determined based on the determination result and stored in a predetermined area of the RAM 66. Accordingly, in step S100, the current operation mode M is read from a predetermined area of the RAM 66 where the operation mode M is stored.
[0025]
Subsequently, the CPU 62 of the electronic control unit 60 uses the power f (M) determined according to the operation mode M as the target output power P *, and the DC power from the fuel cell 40 is converted by the inverter 54 so that the power line 12 The amount of fuel gas supplied to the fuel cell 40 is controlled by controlling the city gas regulating valve 24 and the booster pump 26 so that the AC power supplied to the target output power P * is controlled, or the blower 41 is By controlling, the supply amount of the oxidizing gas is controlled, and the DC / DC converter 52 and the inverter 54 are controlled (step S110). In the present embodiment, when the supply amount of fuel gas or oxidant gas is increased, control is performed so as to gradually increase to the target supply amount in consideration of response delay, and the DC / DC converter 52 is Control is performed so that the DC voltage output to the inverter 54 becomes a constant voltage, and the inverter 54 is controlled so that the AC power output becomes constant power.
[0026]
Thereafter, it is determined whether or not the AC power output from the inverter 54 matches the target output power P *, that is, whether or not the AC power is within a predetermined allowable range of the target output power P * (step S120). If they do not match, the process returns to step S110. If they match, the output voltage Vfc of the fuel cell 40 is read from the voltmeter 51 to determine whether or not the output voltage Vfc is stable (step S130). In the present embodiment, it is determined that the output voltage Vfc is stable when the output voltage Vfc of the fuel cell 40 falls within a predetermined range continuously for a predetermined time. When the output voltage Vfc is not stable in step S130, the process returns to step S110 again. When the output voltage Vfc is stable, the output voltage Vfc at that time is stored as a reference voltage value Vs in a predetermined area of the RAM 66 (step S140). Then, the process returns to S100 again.
[0027]
Next, the voltage drop countermeasure program illustrated in FIG. 3 will be described. When this voltage drop countermeasure program is executed as an interrupt process, the CPU 62 of the electronic control unit 60 first reads the output voltage Vfc of the fuel cell 40 from the voltmeter 51 (step S200), and then from the reference voltage value Vs. A value obtained by subtracting the output voltage Vfc is set as a voltage drop degree ΔV (step S210), and the reduction amount of the target output power is determined step by step according to the drop width of the voltage drop degree ΔV. Here, V0, V1, V2, and V3 (V0> V1> V2> V3) are stored in advance in the ROM 64 as determination values for determining the drop width of the voltage drop degree ΔV, and the target output power is reduced according to the drop width. The widths W1, W2, and W3 (W1> W2> W3) are also stored in the ROM 64 in advance.
[0028]
The CPU 62 of the electronic control unit 60 determines whether or not the voltage drop degree ΔV exceeds the determination value V0 (step S220), and when it exceeds, that is, when the drop width is extremely large, the temporary output power value is set to zero, The target output power P * is set (step S230). On the other hand, when the voltage drop ΔV is equal to or less than the determination value V0 in step S220, it is determined whether or not the voltage drop ΔV exceeds the determination value V1 (step S240). The provisional output power value is set to a value obtained by subtracting the reduction width W1 from the power f (M) set corresponding to the current mode M, and this is set as the target output power P * (step S250). On the other hand, when the voltage drop ΔV is equal to or smaller than the determination value V1 in step S240, it is determined whether or not the voltage drop ΔV exceeds the determination value V2 (step S260). Sometimes, the provisional output power value is set to a value obtained by subtracting the reduction width W2 from the power f (M), and this is set as the target output power P * (step S270). On the other hand, when the voltage drop ΔV is less than or equal to the determination value V2 in step S260, it is determined whether or not the voltage drop ΔV exceeds the determination value V3 (step S280). The provisional output power value is set to a value obtained by subtracting the reduction width W3 from the power f (M), and this is set as the target output power P * (step S290). On the other hand, when the voltage drop ΔV is equal to or less than the determination value V3, that is, when the drop width is within the allowable range, the program is terminated as it is. In this way, the target output power P * is set according to the drop width of the voltage drop degree ΔV, and the decrease width of the target output power P * is set larger as the drop width is larger.
[0029]
Then, the CPU 62 of the electronic control unit 60 controls the city gas regulating valve 24 and the booster pump 26 so that the AC output from the inverter 54 becomes the target output power P * after steps S230, S250, 270, and S290. Thus, the supply amount of the fuel gas to the fuel cell 40 is controlled, the supply amount of the oxidizing gas is controlled by controlling the blower 41, and the DC / DC converter 52 and the inverter 54 are controlled (step). S300). Subsequently, it is determined whether or not the output voltage Vfc of the fuel cell 40 is stable (step S310). When the output voltage Vfc is not stable, the process returns to step S300 again. When the output voltage Vfc is stable, the target output power P is restored. * Is increased by a small amount ΔP (step S320), and it is determined whether or not the increased target output power P * has reached power f (M) (step S330). If not, the process returns to step S300. When it reaches and reaches, this interrupt processing is terminated. Thereafter, the constant power control program of FIG. 2 is executed as the main process, and constant power control is performed with the power f (M) as the target output power P *.
[0030]
Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The voltmeter 51 of this embodiment corresponds to the voltage detection means of the present invention, the electronic control unit 60 corresponds to the voltage control means and the voltage drop determination means, and the DC / DC converter 52 and the inverter 54 correspond to the power conversion means. .
[0031]
According to the fuel cell power generation system 20 of the present embodiment described above, a drop in the output voltage Vfc of the fuel cell 40 is often seen temporarily, so that direct current power from the fuel cell 40 is converted by the inverter 54. The AC power supplied to the power line 12 is temporarily lowered to a target output power P * lower than the power f (M), and the process waits for the output voltage Vfc of the fuel cell 40 to stabilize. Therefore, when the output voltage Vfc of the fuel cell 40 drops, it can be dealt with without greatly affecting the operating status of the entire system.
[0032]
Further, after the output voltage Vfc of the fuel cell 40 is stabilized by controlling the AC power from the inverter 54 to be the provisional output power value, the AC power from the inverter 54 is gradually increased to obtain the original target power value. Therefore, even if a response delay occurs when the amount of fuel gas supplied to the fuel cell 40 is increased, the AC power from the inverter 54 is converted into the power f (M). ) Can be returned smoothly. In particular, since the fuel cell 40 is supplied with the fuel gas from the reformer 30 that reforms the city gas into a hydrogen-rich fuel gas, the city gas to the reformer 30 is increased in order to increase the supply amount of the fuel gas. Therefore, it is important to gradually increase the AC power from the inverter 54 and return it to the original power f (M).
[0033]
Furthermore, since it can be determined whether or not the output voltage Vfc has dropped due to whether or not the output voltage Vfc of the fuel cell 40 has become smaller than the reference voltage value Vs, it can be easily determined whether or not the output voltage has dropped. Since the output voltage Vfc that was stable when the AC power from the inverter 54 is controlled to the power f (M) is used as the reference voltage value Vs, the optimum reference voltage value Vs under the operating conditions at that time can be easily obtained. It can be set, and it can be appropriately determined whether or not the output voltage Vfc has dropped.
[0034]
Furthermore, the provisional output power value is determined in a stepwise manner in accordance with the drop width of the output voltage Vfc. Specifically, the provisional output power value is set to be lower as the drop width is larger. That is, when the drop width is large, the output voltage Vfc of the fuel cell 40 tends to be difficult to stabilize. Therefore, the output voltage of the fuel cell can be stabilized as soon as possible by reducing the provisional output power value. Further, since the output voltage Vfc of the fuel cell tends to be stable when the drop width is small, by setting the provisional output power value to a value close to the power f (M) corresponding to the mode M, the original power can be obtained as soon as possible. It is possible to return to f (M).
[0035]
It should be noted that the present invention is not limited to the above-described embodiment, and can of course be implemented in various forms within the scope belonging to the technical scope of the present invention.
[0036]
For example, in the above-described embodiment, the stack voltage is adopted as the output voltage Vfc of the fuel cell. However, the cell voltage for each cell may be adopted, and the AC power from the inverter 54 is set as the target output power P *. However, the direct current power from the fuel cell may be controlled to be constant power.
[0037]
  In the above-described embodiment, the output voltage Vfc of the fuel cell 40 is compared with the reference voltage value Vs to determine whether or not the output voltage Vfc has dropped, but the time differential value of the output voltage Vfc of the fuel cell 40 is determined. It may be determined whether or not the output voltage Vfc has dropped depending on whether or not the voltage has become smaller than a predetermined threshold value, so that the fact that the output voltage Vfc has fallen can be detected relatively quickly. it can. At this time, the provisional output power value is stepwise according to the magnitude of the time differential value.It has been established.Specifically, the larger the absolute value of the time derivative (negative value), the lower the value.It has been established.
[0038]
Furthermore, in step S310 of the above-described embodiment, whether or not the output voltage Vfc of the fuel cell 40 is stable is determined for a predetermined time, for example, as in step S130, and the output voltage Vfc of the fuel cell 40 is within a predetermined range. May be determined to be stable when the output voltage changes with time, that is, when the change in output voltage with respect to time changes is small, the condition that the change in output voltage with respect to time changes is small and the voltage of each single cell of the fuel cell 40 are monitored. Then, it is preferable to determine that the output voltage Vfc is stable when both of the conditions that the voltage variation of each single cell is small are satisfied. At this time, whether or not the variation in the voltage of each single cell is small is obtained by, for example, obtaining the difference between the maximum value and the minimum value among the voltages of each single cell and determining that the variation is small if the difference is within a predetermined range. May be.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an outline of a configuration of a fuel cell power generation system 20 according to an embodiment of the present invention.
FIG. 2 is a flowchart showing an example of a constant power control program executed by the electronic control unit 60;
FIG. 3 is a flowchart showing interrupt processing executed by the electronic control unit 60;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Commercial power supply, 12 Electric power line, 14 Circuit breaker, 16 Load, 18 Circuit breaker, 20 Fuel cell power generation system, 22 Gas piping, 24 Control valve, 26, 28 Booster pump, 27 Desulfurizer, 30 Reformer, 32 Combustion Part, 34 CO selective oxidation part, 40 fuel cell, 41 blower, 42 heat exchanger, 43 circulation pump, 44 hot water storage tank, 46 pump, 51 voltmeter, 52 DC / DC converter, 54 inverter, 55 circuit breaker, 56 DC / DC converter, 58 load power meter, 60 electronic control unit, 62 CPU, 64 ROM, 66 RAM, 68 timer.

Claims (9)

A fuel cell power generation system capable of supplying output power derived from a fuel cell to a power supply line that supplies power from another system power supply to a load,
Voltage detection means for detecting the output voltage of the fuel cell;
Power control means for controlling the output power derived from the fuel cell to be a predetermined target power value;
Voltage drop determining means for determining whether or not the output voltage of the fuel cell has dropped when the output power derived from the fuel cell is controlled to the target power value;
The power control means, when the voltage drop determination means determines that the output voltage of the fuel cell has dropped, causes the output power derived from the fuel cell to be a provisional power value lower than the target power value. And a means for controlling the output power derived from the fuel cell to substantially match the original target power value after the output power derived from the fuel cell is stabilized at the provisional power value.
The provisional power value is determined in a stepwise manner such that the provisional power value decreases as the drop width of the output voltage of the fuel cell increases.
Fuel cell power generation system. The power control means is derived from the fuel cell after the output voltage of the fuel cell is stabilized by controlling the output power derived from the fuel cell to be a provisional power value lower than the target power value. 2. The fuel cell power generation system according to claim 1, wherein the output power is made to substantially coincide with the original target power value by increasing the output power step by step by a predetermined minute amount . The voltage drop determining means determines whether or not the output voltage of the fuel cell becomes smaller than a predetermined reference voltage value when the output power derived from the fuel cell is controlled to the target power value by the power control means. The fuel cell power generation system according to claim 1 or 2, wherein it is determined whether or not the output voltage of the fuel cell has dropped. 4. The fuel cell according to claim 3, wherein the reference voltage value is an output voltage of the fuel cell that is stable when output power derived from the fuel cell is controlled to the target power value by the power control unit. 5. Power generation system. The voltage drop determining means is configured such that the time differential value of the output voltage of the fuel cell is lower than a predetermined threshold value when the output voltage derived from the fuel cell is controlled to the target power value by the power control means. The fuel cell power generation system according to claim 1 or 2, wherein it is determined whether or not the output voltage of the fuel cell has dropped depending on whether or not it has become smaller. The fuel cell, the fuel cell power generation system according to any one of claims 1 to 5, the fuel gas hydrocarbon fuel from the reforming unit for reforming the hydrogen-rich fuel gas is supplied. The fuel cell power generation system according to any one of claims 1 to 6 ,
Power conversion means for converting DC power from the fuel cell into desired power to be supplied to the power supply line,
Output power derived from the fuel cell is power after being converted by the power conversion means. A method for operating a fuel cell power generation system capable of supplying output power derived from a fuel cell to a power supply line that supplies power from another system power supply to a load,
When the output power derived from the fuel cell is controlled to be a predetermined target power value, it is determined whether the output voltage of the fuel cell has dropped, and the output voltage of the fuel cell has dropped When determined, the output power derived from the fuel cell is controlled to be a provisional power value lower than the target power value, and the output power derived from the fuel cell is stabilized at the provisional power value, The output power derived from the fuel cell is controlled so as to substantially match the original target power value, and the provisional power value is stepwise so as to decrease as the output voltage drop of the fuel cell increases. Determined,
Operation method of fuel cell power generation system. After the output voltage of the fuel cell is stabilized by controlling the output power derived from the fuel cell to be a provisional power value lower than the target power value, the output power derived from the fuel cell is predetermined. The operation method of the fuel cell power generation system according to claim 8 , wherein the fuel cell power generation system is made to substantially coincide with the original target power value by stepping up in small increments .

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