JP2019029108A - Fuel cell power generation system and method for controlling fuel cell power generation system - Google Patents

Abstract

To provide a fuel cell power generation system achieving an autonomous function in which additional equipment is not needed.SOLUTION: A fuel cell power generation system 1 includes a control unit 30 to change controls in the case of system interconnection operation and in the case of autonomous operation. The control unit 30 controls at least one of the supply amount of anode gas supplied to an anode 12, the amount of exhaust of exhausted anode off gas, and the supply amount of cathode gas supplied to a cathode 14 thereby to change controls in the case of system interconnection operation and in the case of autonomous operation.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a fuel cell power generation system and a control method for the fuel cell power generation system.

  Conventionally, a fuel cell is known as a system that directly converts chemical energy of a fuel into electricity. Fuel cells that directly extract electricity by electrochemically reacting hydrogen, which is a fuel, and oxygen, which is an oxidant, can extract electric energy with high efficiency, have excellent silence, and are harmful. It is a system with excellent environmental characteristics that does not emit exhaust gas. Until recently, relatively large PAFC (Phosphoric Acid Fuel Cell) has been mainly developed, but recently, small PEFC (Polymer Electrolyte Fuel Cell) has been developed. Has become active. As a result, commercialization of a household fuel cell power generation system has also been realized. In FY 2016, about 150,000 units are installed in Japan. In addition, a pure hydrogen fuel cell that directly introduces pure hydrogen has been developed for a future hydrogen society.

  The pure hydrogen fuel cell system has high efficiency as described above, but in order to maintain this efficiency, a mechanism that uses almost the entire amount of hydrogen without waste is important. In such a fuel cell system, it is difficult to change the output quickly, and generally the minimum output to the maximum output is changed in 30 seconds to 1 minute. When used in grid connection during normal operation, the time required for output change is not a significant problem. However, in the case of performing self-sustained power generation such as when a power failure occurs in the system, the power generation output depends on the load of electricity to be connected, and it may be necessary to respond to an increase or decrease instantaneously. In the prior art, in order to cope with this output change, a battery or a capacitor is used as a buffer material (heater). However, the cost increases.

JP 2008-152997 A

  Therefore, a problem to be solved by an embodiment of the present invention is to provide a fuel cell system that realizes a self-supporting function that eliminates the need for an additional device serving as a buffer material.

A fuel cell system according to an embodiment includes:
An anode supplied with an anode gas containing hydrogen gas; and a cathode supplied with a cathode gas containing oxygen gas; and the hydrogen gas supplied to the anode and the oxygen gas supplied to the cathode. Using the fuel cell stack to generate electricity,
An electrical system for extracting electricity from the fuel cell stack;
A control unit for controlling supply of the anode gas to the anode and supply of the cathode gas to the cathode, wherein the electric system is connected to another power system, and the electric A control unit for changing the control in the case of a self-sustaining operation in which the system is connected to a self-sustained load without being connected to the other power system; and
A first supply path for supplying the anode gas to the anode;
A first discharge path for discharging used anode off-gas from the anode;
A second supply path for supplying the cathode gas to the cathode;
With
The control unit supplies the anode gas supplied from the first supply path to the anode, discharges the anode off-gas discharged from the first discharge path, and supplies the cathode from the second supply path to the cathode. And controlling the at least one of the supply amounts of the cathode gas so that the electric system is connected to another electric power system, and the electric system is connected to the other electric power system. Without changing the control in the case of the independent operation connected to the independent load.

  According to the embodiment of the present invention, it is possible to realize a self-supporting function that does not require a cushioning material.

The block diagram which shows the function of the fuel cell system which concerns on 1st Embodiment. The flowchart which shows the transfer process to independent operation mode. The figure which shows the control value of the gas supply amount and discharge | emission amount at the time of grid connection operation | movement. The figure which shows the control value of the gas supply amount and discharge | emission amount at the time of the independent operation which concerns on 1st Embodiment. The block diagram which shows the function of the fuel cell system which concerns on 2nd Embodiment. The figure which shows the control value of the gas supply amount and discharge | emission amount at the time of the independent operation which concerns on 2nd Embodiment. The figure which shows the control value of the gas supply amount and discharge | emission amount at the time of the independent operation which concerns on 3rd Embodiment. The block diagram which shows the function of the fuel cell system which concerns on 4th Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. This embodiment does not limit the present invention.

(First embodiment)
The fuel cell system 1 according to the present embodiment is supplied to the supply amount of hydrogen gas supplied to the anode and the cathode when transitioning from a grid-connected operation connected to another power system to a self-sustaining power generation operation. By increasing the supply amount of oxygen gas, the output change of power generation can be changed during grid connection so that it can cope with the change in power generation amount necessary for the self-supporting load connected to the fuel cell system 1 without using a buffer material. Compared to, it is going to be done at high speed.

  FIG. 1 is a block diagram showing functions of the fuel cell system 1 according to the first embodiment. As shown in FIG. 1, the fuel cell system 1 includes a fuel cell stack 10, an electrical system 20, and a controller 30.

  The fuel cell stack 10 is an apparatus that includes an anode 12 and a cathode 14 and generates power by reacting hydrogen gas and oxygen gas. In the description of the present embodiment, since the processing related to power generation is the same as that of a general apparatus, other configurations such as an electrolyte, a separator, and an external conductor connecting the anode 12 and the cathode 14 are not particularly described. However, what is necessary for the fuel cell stack 10 is provided. Further, for explanation, only one set of cells including the anode 12 and the cathode 14 is shown, but this also has a general configuration, and the fuel cell stack 10 includes a plurality of anodes 12, And a cathode 14.

  The anode 12 is a device for reacting an anode gas containing hydrogen gas with an electrolyte. As a means for supplying anode gas to the anode 12, a first supply path 500 is connected to the anode 12. Further, a first discharge path 502 is connected to the anode 12 via a circulation path 504 as means for discharging the anode off gas after being reacted with the electrolyte.

  The first supply path 500 includes, for example, a first fuel pressure adjustment valve 120 that is a self-operating adjustment valve, and a first fuel cutoff valve 122 that is a valve that shuts off fuel. The first fuel pressure control valve 120 is a valve that adjusts the pressure so as to adjust the supply amount of the anode gas supplied to the anode 12. A high pressure (for example, a pressure higher than 10 kPa) is applied on the gas input side of the first fuel pressure control valve 120. The first fuel pressure adjustment valve 120 adjusts the high-pressure gas so that the pressure becomes an appropriate supply amount (for example, 6 kPa) on the output side.

  The anode gas converted to an appropriate pressure through the first fuel pressure control valve 120 is shut off by the first fuel shut-off valve 122 and adjusted to be supplied to the anode 12 at an appropriate timing. In this manner, the supply amount of the anode gas supplied to the anode 12 through the first fuel pressure adjustment valve 120 and the first fuel cutoff valve 122 is adjusted.

  In the anode 12 to which the anode gas is supplied, the electrolyte and the hydrogen gas react, and hydrogen ions and electrons are supplied to the cathode 14. The anode gas after reacting in the anode 12 flows into the circulation path 504.

  The circulation path 504 is connected to the first supply path 500 and is connected to the first discharge path 502 via the first anode bleed valve 124. An anode recycle blower 126 is provided so that the anode gas before the reaction in the anode 12 does not flow from the first supply path 500 to the circulation path 504. When the first anode bleed valve 124 is closed by the anode recycle blower 126, the anode off gas flows into the circulation path 504. The anode off gas reflows into the anode 12 via the first supply path 500, whereby the hydrogen gas remaining in the anode off gas can be reused in the anode 12. A check valve may be provided at a connection point between the first supply path 500 and the circulation path 504 so that the gas does not flow into the circulation path 504 from the first supply path 500.

  The first discharge path 502 is connected to the anode 12 via the circulation path 504 and the first anode bleed valve 124, and discharges the anode off gas to the outside when the first anode bleed valve 124 is open. The first anode bleed valve 124 is a path for discharging the anode off-gas from the anode 12 in this way, and is opened at an appropriate timing in consideration of the recycling efficiency of the anode off-gas, and passes through the first discharge path 502. The anode off gas is discharged to the outside.

  The cathode 14 is a device that generates direct current electricity by chemically reacting oxygen gas in the air with hydrogen gas and electrons separated by the anode 12. A second supply path 510 is connected to the cathode 14 as means for flowing air containing oxygen gas (cathode gas) into the cathode 14. A second discharge path 512 is connected to the cathode 14 as means for discharging the cathode off gas after the reaction.

  The second supply path 510 is provided with a cathode blower 140 that supplies cathode gas to the cathode 14. The cathode blower 140 adjusts the inflow amount of the cathode gas so that an appropriate amount of cathode gas is supplied to the cathode 14. The cathode off gas used for the chemical reaction at the cathode 14 is discharged to the outside through the second discharge path 512.

  The electrical system 20 takes out the electricity generated by the chemical reaction at the cathode 14 and transmits it to an appropriate location. The electrical system 20 includes, for example, an inverter 22. The configuration of the electric system 20 is the same as that of a general fuel cell system, and therefore will not be described in detail.

  The inverter 22 converts the generated direct current electricity into alternating current electricity and transmits the electricity. At the time of grid connection in normal operation, this AC electricity is transmitted to the grid 40 that is linked. When the normal operation such as a power failure is not performed, the AC electricity is transmitted to the self-supporting load 42, and the fuel cell system 1 is switched to the self-supporting operation. The fuel cell system 1 preferably changes its power generation output based on these respective loads. That is, it is preferable to control the power generation amount of the fuel cell stack 10 based on the load connected to the fuel cell system 1.

  The controller 30 is a device that controls the above-described valves and blowers. When the controller 30 is controlled by the valve and the blower, the fuel cell system 1 adjusts the output to be generated.

  FIG. 2 is a flowchart showing processing of the operation of the fuel cell system 1 according to the present embodiment. As a premise, as described above, the fuel cell system 1 is operated by grid connection in normal times, and performs a self-sustained operation when a power failure of the system occurs and it is not a normal operation.

  First, as described above, in normal times, the fuel cell system 1 is used in a grid connection connected to another power system and is operating in a grid connection mode (step S10). When the grid system is operating normally, the fuel cell system 1 continues to operate in this grid connection mode.

  FIG. 3 shows a cathode flow rate control for controlling the supply amount of the cathode gas to the cathode 14 in the grid connection mode, an anode recycle control for controlling the recycle amount (rate) of the anode off gas to the anode 12 in the circulation path 504, A table showing anode bleed control for controlling the discharge amount of the anode off-gas from the anode 12 in the discharge passage 502 and anode supply pressure control for controlling the supply amount of the anode gas supplied from the first supply passage 500 to the anode 12. It is.

  As shown in FIG. 3, the controller 30 controls the supply, recycling, and discharge of each gas in the grid connection mode. During operation in the grid connection mode, control is performed to increase the power generation efficiency from the fuel. For example, control is performed so that almost all of the hydrogen gas contained in the anode gas supplied to the anode 12 is used without waste. Specifically, the recycling of the hydrogen gas contained in the anode off gas is promoted by keeping the anode off gas recycling rate high. Further, the supply amount of the cathode gas flowing into the cathode is also adjusted so that a chemical reaction using hydrogen ions generated at the anode 12 without waste is possible.

  As an example, the controller 30 controls the cathode flow rate control so that the utilization rate of the cathode gas (air) is constant, and controls the anode recycle blower so that the fuel utilization rate is constant. In order to increase the efficiency of recycling, the anode bleed control is performed so that the minimum necessary anode off gas is discharged from the first discharge path 502 to the outside. The first fuel pressure control valve 120 is controlled so that the pressure of the anode gas supplied is 6 kPa as described above.

  For example, when the first anode bleed valve 124 is opened, the first fuel cutoff valve 122 is opened at the same time or before and after. As described above, the anode off gas having a low hydrogen gas concentration is discharged through the first discharge path 502, and the anode gas rich in hydrogen gas is supplied to the anode 12 through the first supply path 500. To.

  Note that the anode bleed amount being the necessary minimum bleed control is a method of controlling the impurities in the fuel to be a predetermined value or less, for example. As a result of such control, the anode gas rich in hydrogen gas can be introduced before the amount of hydrogen gas contained in the anode off-gas is reduced to such an extent that it is not suitable for power generation.

  In this way, the first anode bleed valve 124 and the first fuel cutoff valve 122 are controlled to control the supply and discharge of the gas containing hydrogen gas, thereby efficiently using the hydrogen gas contained in the anode gas and the anode off gas. It becomes possible. Note that the above description is described as an example, and the pressure and the like can be changed to those suitable for the system. Moreover, it is good also as the operating method of the fuel cell system in another general grid connection.

  Returning to FIG. 2, the fuel cell system 1 may monitor whether or not normal operation is possible (step S12). In the monitor information, when the operation in the grid connection mode is possible, that is, when the independent operation is not performed (step S12: NO), the fuel cell system 1 continues the operation in the grid connection mode. On the other hand, when it is impossible or difficult to operate in the grid connection mode due to a power failure or the like, that is, when the autonomous operation is performed (step S12: YES), the fuel cell system 1 sets the operation mode to the autonomous operation mode. (Step S13).

  In step S12, there is no need to constantly monitor, and confirmation may be performed at predetermined time intervals. As another method, when normal operation cannot be performed, the determination in step S12 may be made as an interruption process.

  FIG. 4 is a table showing parameters for controlling the amount of gas supplied to the anode 12 and the cathode 14 in the self-sustaining operation mode according to the present embodiment.

  For example, when an abnormality occurs in the system, the output control of the inverter 22 is switched from the current control to the voltage control, and the operation is shifted to the independent operation. By doing so, instantaneous output fluctuations are generated by the self-supporting load 42 which is a connected power load. In order to cope with this output fluctuation, the controller 30 controls each input value and output value as follows.

  When shifting from the grid connection mode to the self-sustained operation mode, the controller 30 shifts the control of gas supply and discharge as shown in the table of FIG. That is, the controller 30 transitions the cathode flow rate control from the constant air utilization rate control to the constant flow rate control corresponding to the rated power output, and the anode recycling control from the constant fuel usage rate control to the constant control equivalent to the rated power output. The anode bleed control is changed from the necessary minimum bleed control to the maximum output bleed control. Therefore, in this case, the amount of cathode gas (air) flowing through the cathode 14 and the amount of anode gas (fuel) flowing through the anode 12 are maximized, and power generation is possible at a rating or near the rating. In such a state, it is possible to output power corresponding to the rating by controlling the current of the inverter 22.

  Specifically, the above control is performed as follows as an example. When performing the cathode flow rate control, the controller 30 controls the cathode blower 140 so that the flow rate of the cathode gas flowing through the cathode blower 140 corresponds to the rated output. When performing the anode recycle control, the controller 30 controls the anode recycle blower 126 so that the flow rate of the anode off gas flowing through the anode recycle blower 126 corresponds to the rated output. When performing the anode bleed control, the controller 30 controls the maximum output bleed by opening the first anode bleed valve 124.

  In addition to the above, the controller 30 may control the first fuel cutoff valve 122 to be opened as appropriate so that the supply amount of the anode gas and the discharge amount of the anode off-gas are equal.

  Here, the rating is, for example, a value indicating the maximum input or output that the system can withstand long-term continuous operation. In this embodiment, it is not limited to the maximum input and the maximum output, and includes an input and output amount slightly less than the maximum depending on the state of each device. For example, the value of the cathode flow rate control is set to 95% or more corresponding to the rated power generation output that is the first predetermined value, and similarly the value of the anode recycling control is set to 95% corresponding to the rated power generation output that is the second predetermined value. It is good also as above. Depending on the reliability of the system, it may be higher than 98% instead of 95%.

  Here, the rating equivalent is the value corresponding to the rated output as described above when trying to output the rated value, that is, the output fluctuation in the device and the output fluctuation due to the environment when outputting, Assume that the concept includes a case where the output value is slightly lower than the rating. This is a concept that includes the case where the output amount is set to be slightly smaller than the rating in consideration of the safety of the device. The first predetermined value mentioned above refers to the value of the cathode flow rate required for performing an output corresponding to this rating. Similarly, the second predetermined value refers to an anode recycling control value required for an output corresponding to this rating.

  In this case, the anode off-gas discharged from the first anode bleed valve 124 may be equal to or greater than a third predetermined value. The third predetermined value is, for example, a value that is controlled so that anode gas that enables output of 95% of the rated output is supplied to the anode 12. For example, the first anode bleed valve 124 is opened. The state which is controlling to the state which is doing. The third predetermined value is also the same as described above, and refers to the value of the anode off-gas emission amount necessary for outputting the output corresponding to the rating.

  By controlling in this way, the process flow rate consumed by the fuel cell stack 10 is equivalent to the rated output for the cathode 14 and the flow rate close to the rated output is flowing for the anode 12 as well. It becomes possible to respond to load changes. Note that the power generation efficiency at low output decreases by several percent because the auxiliary machine operates at the rated output and the anode bleed amount increases. In view of the time, the value of electric power is very high and the reliability and certainty of power generation is more important than the efficiency of power generation versus fuel, so it is not a big problem.

  As described above, according to the present embodiment, in the self-sustained operation mode, even when the output to be generated according to the self-sustained load needs to increase or decrease instantaneously, it is expensive and has a high response speed. It is possible to respond to instantaneous output changes without using a compressor or the like. That is, it is possible to supply the fuel cell system 1 that can cope with the instantaneous output change in the self-sustaining operation mode without a significant cost increase. As a result, during grid connection, priority is given to the efficiency of power generation against fuel, and in autonomous operation during abnormalities such as power outages, control is performed to give priority to the rate of change in output of power generation to respond to autonomous loads. The power generation output of the fuel cell stack 10 can be appropriately changed based on the load connected to the fuel cell system 1.

  By performing the above-described control, for example, in the case of autonomous operation, the fuel cell system 1 can no longer endure against a sudden change in the autonomous load 42, and the fuel cell system is provided by the function of the safety circuit provided in the fuel cell system 1. It becomes possible to suppress the possibility that 1 must be shut down. As a result, the reliability of the operation of the fuel cell system 1 can be improved, and the possibility of preventing an unexpected failure during the self-sustaining operation of the fuel cell system 1 itself can be increased.

  It is not necessary to control all the values shown in the table of FIG. 4, and a certain effect can be obtained by controlling at least one value as shown in FIGS. This also applies to the following embodiments.

(Second Embodiment)
In the first embodiment described above, it is possible to increase the speed of output change by controlling the anode recycling amount and the cathode flow rate. However, in this embodiment, the anode gas supply pressure is further increased. By doing so, it is intended to increase the speed of the output change. Hereinafter, parts different from the first embodiment will be described in detail.

  FIG. 5 is a functional block diagram of the fuel cell system 1 according to the present embodiment. As shown in FIG. 5, the fuel cell system 1 further adjusts the supply of fuel from the high pressure second fuel pressure adjustment valve 128 and the high pressure second fuel pressure adjustment valve 128 to the first supply path 500. And a second anode bleed valve 132 having a large flow rate installed in parallel with the first anode bleed valve 124 between the circulation path 504 and the first discharge path 502.

  The high-pressure second fuel pressure control valve 128 is, for example, a self-powered control valve, similarly to the first fuel pressure control valve 120. On the other hand, when the pressure of the anode gas output from the first fuel pressure control valve 120 is controlled to 6 kPa, the high-pressure second fuel pressure control valve 128, for example, Is controlled to 10 kPa. As described above, the high-pressure second fuel pressure control valve 128 supplies the anode gas to the first supply path 500 at a pressure higher than that of the first fuel pressure control valve 120.

  FIG. 6 is a table showing parameters for controlling the amount of gas supplied to the anode 12 and the cathode 14 in the self-sustaining operation mode according to the present embodiment. In the fuel cell system 1 in the present embodiment, in the self-sustained operation mode, the controller 30 controls the inflow and exhaust amount of each gas as follows. The cathode flow rate control, anode recycling control, and anode bleed control are controlled in the same manner as in the first embodiment. The anode supply pressure is controlled to a high pressure unlike the first embodiment described above.

  In order to increase the supply pressure of the anode gas as compared with the grid connection mode, the high-pressure second fuel pressure control valve 128 and the second fuel cutoff valve 130 are used. The controller 30 controls the high pressure second fuel pressure control valve 128 and the second fuel cutoff valve 130 installed in parallel with the first fuel pressure control valve 120 and the first fuel cutoff valve 122, so that the supply pressure of the anode gas Is kept higher than usual. Specifically, the controller 30 controls to open the second fuel cutoff valve 130 connected in series to the high-pressure second fuel pressure control valve 128 to which a pressure higher than that of the first fuel pressure control valve 120 is applied. By doing so, an anode gas having a higher pressure than that in the grid connection mode is supplied to the anode 12, and as a result, the supply amount of the anode gas is increased.

  In this case, simply by opening the first anode bleed valve 124, the discharge amount of the anode off gas becomes lower than the supply amount of the anode gas, and the supply amount of the anode gas gradually decreases. For example, the self-supporting load 42 is low. There is a possibility that it becomes impossible to follow the fluctuation of the output when it becomes a high state. Therefore, by opening the large flow rate second anode bleed valve 132 provided in the circulation path 504 and discharging more anode off gas, the anode gas rich in hydrogen gas can be supplied to the anode 12. To.

  As described above, also in this embodiment, some valves are added in the self-sustained operation mode, and it is possible to cope with a change in instantaneous output without adding a high-cost device. Further, as in the present embodiment, by increasing the pressure for supplying the anode gas and increasing the discharge amount of the anode off-gas, it becomes possible to supply more anode gas to the anode 12 for faster output. It is possible to follow changes.

(Third embodiment)
In each of the above-described embodiments, the supply amount of each gas during the self-sustaining operation is controlled so as to correspond to the rated output of the fuel cell stack 10, but in this embodiment, when performing self-sustaining operation, The fuel cell system 1 will be described in which the amount of power generation is set to a slightly lower power generation amount instead of being controlled to be equivalent to the rated output, and the power generation amount is increased if necessary as the self-supporting load 42 increases or decreases.

  FIG. 7 is a table showing parameters for controlling the amount of gas supplied to the anode 12 and the cathode 14 in the self-sustaining operation mode according to the present embodiment. In the fuel cell system 1 in the present embodiment, in the self-sustained operation mode, the controller 30 controls the inflow and exhaust amount of each gas as follows. The cathode flow rate control is controlled to a flow rate equal to or higher than a first predetermined value, for example, a value corresponding to 80% corresponding to the rated output. Similarly, the anode recycling control and the anode bleed control are controlled to a flow rate equal to or higher than a value corresponding to 80% corresponding to the rated output.

  In this way, in the self-sustaining operation mode, for example, power generation corresponding to 80% of the rated output is performed. That is, in the first embodiment described above, the first predetermined value and the second predetermined value are not equivalent to rated (or slightly smaller values than rated) power generation, but are, for example, 80% of the rated output. Set to be. For example, the first predetermined value and the second predetermined value are equivalent to the rated output so that the output change can be followed when the self-supporting load 42 increases or is assumed to increase. Adjust so that

  In this way, it is possible to follow the rate of change of the output value in the self-sustained operation mode, and when the self-sustained load is not so high as to require rated power generation, the amount of hydrogen gas used due to excessive power generation Can also be suppressed. In the above, 80% is given as an example and is not limited to this. For example, when the predetermined value is set to 50% of the rating and the self-sustained load becomes large, the controller 30 may control the power generation amount to change to about 80% of the rating or equivalent to the rating. .

  As described above, according to the present embodiment, in the self-sustaining operation mode, when the self-supporting load 42 is not so high that the rated output is required, the utilization efficiency of hydrogen gas is increased and the output by the self-supporting load 42 is increased. By controlling so that the power generation output is equivalent to the rating when it becomes higher, it becomes possible to adapt to the power output change at high speed.

(Fourth embodiment)
In each of the above-described embodiments, the supply amount of the anode gas is controlled with respect to the pressure of the anode gas in the first supply passage 500 by, for example, the first fuel pressure control valve 120 that is a self-regulating valve. In this embodiment, the anode gas supply amount is controlled by using another device such as an injector.

  FIG. 8 is a block diagram showing functions of the fuel cell system 1 according to the present embodiment. As shown in FIG. 8, the supply of the anode gas is performed via the anode gas supply amount adjusting unit 134. The anode gas supply amount adjusting unit 134 includes, for example, an injector and a pressure gauge.

  The injector is a device that automatically injects a gas controlled by the controller 30. For example, the injector injects an anode gas into the anode 12 at a predetermined interval or a predetermined amount. In this case, the pressure of the anode gas to be injected is measured by a pressure gauge provided therewith. The controller 30 controls the supply amount of the anode gas by referring to the pressure of the anode gas measured by the pressure gauge.

  For example, the same effect as that of the first embodiment can be obtained by setting the pressure of the anode gas injected by the injector so that the pressure indicated by the pressure gauge is 6 kPa. In this case, the same control as in the first embodiment is performed for the other valves. In the present embodiment, the control values for the valves and the like are based on the tables shown in FIGS. 4, 6, and 7.

  As described above, according to the present embodiment, it is possible to cope with output changes in the self-sustaining operation mode by controlling the supply amount of the anode gas using another device such as an injector. As described above, it is possible to obtain the same effect as that of the above-described embodiment not by the regulating valve but also by another inexpensive device that controls the supply amount.

  In all of the above-described embodiments, only the valves and the like that are necessary to adjust the pressure or the supply amount are described. Therefore, the adjustment valves and the like that are necessary for the fuel cell system 1 are described. It is assumed that it is provided. In addition, as an example, the first fuel cutoff valve 122 and the second fuel cutoff valve 130 of FIG. 5 are connected in series, but these valves may be connected in parallel. That is, a set of valves connected in series between the first fuel pressure control valve 120 and the first fuel cutoff valve 122, and a valve connected in series between the high pressure second fuel pressure control valve 128 and the second fuel cutoff valve 130. May be connected in parallel. Thus, the non-essential part of the invention can be changed or replaced as appropriate.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof. Of course, it is possible to appropriately combine these embodiments partially within the scope of the present invention.

1: fuel cell system, 10: fuel cell stack, 12: anode, 120: first fuel pressure regulating valve, 122: first fuel shut-off valve, 124: first anode bleed valve, 126: anode recycle blower, 14: cathode 140: cathode blower, 20: electrical system, 22: inverter, 30: controller, 40: electrical system, 42: self-supporting load

Claims (9)

An anode supplied with an anode gas containing hydrogen gas; and a cathode supplied with a cathode gas containing oxygen gas; and the hydrogen gas supplied to the anode and the oxygen gas supplied to the cathode. Using the fuel cell stack to generate electricity,
An electrical system for extracting electricity from the fuel cell stack;
A control unit for controlling supply of the anode gas to the anode and supply of the cathode gas to the cathode, wherein the electric system is connected to another power system, and the electric A control unit for changing the control in the case of a self-sustaining operation in which the system is connected to a self-sustained load without being connected to the other power system; and
A first supply path for supplying the anode gas to the anode;
A first discharge path for discharging used anode off-gas from the anode;
A second supply path for supplying the cathode gas to the cathode;
With
The control unit supplies the anode gas supplied from the first supply path to the anode, discharges the anode off-gas discharged from the first discharge path, and supplies the cathode from the second supply path to the cathode. And controlling the at least one of the supply amounts of the cathode gas so that the electric system is connected to another electric power system, and the electric system is connected to the other electric power system. Change the control in the case of independent operation connected to an independent load without
Fuel cell power generation system. The controller is
In the case of the grid interconnection operation, control is performed to give priority to the efficiency of the power generation amount with respect to the amount of fuel to be supplied,
In the case of the self-sustained operation, control is performed to give priority to the change speed of the output to be generated.
The fuel cell power generation system according to claim 1.   3. The fuel cell according to claim 1, wherein the control unit controls the cathode gas supply amount supplied from the second supply path to be equal to or more than a first predetermined amount in the self-sustained operation. Power generation system.   4. The control unit according to claim 1, wherein in the self-sustained operation, the control unit controls the supply amount of the anode gas supplied from the first supply path to be equal to or greater than a second predetermined amount. 5. The fuel cell power generation system described.   In the self-sustained operation, the control unit increases the supply pressure of the anode gas supplied from the first supply path, and controls the supply amount of the anode gas to be equal to or higher than the second predetermined amount. The fuel cell power generation system according to claim 4. An injector connected to the first supply path and for flowing the anode gas into the first supply path;
5. The fuel cell power generation system according to claim 4, wherein the control unit controls the injector to control a supply amount of the anode gas in the case of the independent operation.   The fuel according to any one of claims 1 to 4, wherein the control unit controls the discharge amount of the anode off-gas discharged from the discharge path to be equal to or greater than a third predetermined amount in the self-sustained operation. Battery power generation system. A circulation path connected to the first discharge path and the first supply path and re-supplying the anode off-gas reused at the anode to the anode;
The control unit controls the resupply amount of the anode off gas supplied from the circulation path to the anode, and changes the control in the case of the grid connection operation and the case of the independent operation.
The fuel cell power generation system according to any one of claims 1 to 5. An anode supplied with an anode gas containing hydrogen gas; and a cathode supplied with a cathode gas containing oxygen gas; and the hydrogen gas supplied to the anode and the oxygen gas supplied to the cathode. Using the fuel cell stack to generate electricity,
An electrical system for extracting electricity from the fuel cell stack;
A control unit for controlling supply of the anode gas to the anode and supply of the cathode gas to the cathode;
A first supply path for supplying the anode gas to the anode;
A first discharge path for discharging used anode off-gas from the anode;
A second supply path for supplying the cathode gas to the cathode;
A control method for a fuel cell power generation system comprising:
The control unit supplies the anode gas supplied from the first supply path to the anode, the anode off-gas discharged from the first discharge path, and the cathode supplied from the second supply path. And controlling the at least one of the supply amounts of the cathode gas so that the electric system is connected to another electric power system, and the electric system is connected to the other electric power system. Change the control in the case of independent operation connected to an independent load without
Control method of fuel cell power generation system.

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