Fuel cell power generation system and control method

Abstract

To ensure energy conservation.SOLUTION: A fuel cell power generation system includes N fuel cells, in which N is an integer of 2 or greater, an output control device that causes the N fuel cells to perform an output fluctuation operation that fluctuates the output power, and a cooling system that, for the N fuel cells, increases the capacity of cooling the kth fuel cell during a first time period in which the kth fuel cell performs the output fluctuation operation, in which k is an integer of 1 or greater and N or less, to be greater than the capacity of cooling the kth fuel cell during a second time period in which the kth fuel cell does not perform the output fluctuation operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a fuel cell power generation system and a control method. [Background technology]

[0002] 2. Description of the Related Art A fuel cell system is known that has a cooling system that circulates a coolant in order to cool a stack of multiple fuel cells (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-136205 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the output power of a fuel cell fluctuates, the capacity to cool the fuel cell may become insufficient. However, if there is always a margin in the capacity to cool the fuel cell, there is a risk that the energy saving performance will decrease. In particular, when there are multiple fuel cells to be cooled, the greater the number of fuel cells, the more likely it is that the energy saving performance will decrease significantly.

[0005] The present disclosure provides a fuel cell power generation system and a control method that can ensure energy conservation. [Means for solving the problem]

[0006] The fuel cell power generation system according to the first embodiment comprises: N fuel cells, where N is an integer greater than or equal to 2; an output control device that causes the N fuel cells to perform an output fluctuation operation in which the output power is varied; and a cooling system that, for the N fuel cells, increases the capacity to cool the kth fuel cell during a first time period when the kth fuel cell performs the output fluctuation operation, more than the capacity to cool the kth fuel cell during a second time period when the kth fuel cell does not perform the output fluctuation operation, where k is an integer greater than 1 and less than N.

[0007] A second aspect is the fuel cell power generation system of the first aspect, The cooling system increases its capacity to cool the kth fuel cell prior to the first time period.

[0008] A third aspect is a fuel cell power generation system according to the first or second aspect, The cooling system increases its ability to cool the kth fuel cell until after the first time period.

[0009] A fourth aspect is a fuel cell power generation system according to any one of the first to third aspects, The second time period is a time period during which none of the N fuel cells performs the output fluctuation operation.

[0010] A fifth aspect is a fuel cell power generation system according to any one of the first to fourth aspects, The cooling system collectively increases the capacity to cool each of the N fuel cells.

[0011] A sixth aspect is a fuel cell power generation system according to any one of the first to fifth aspects, The cooling system increases the capacity to cool each of the N fuel cells during a time period when any one or more of the N fuel cells is performing the output fluctuation operation, more than the capacity during a time period when none of the N fuel cells is performing the output fluctuation operation.

[0012] A seventh aspect is a fuel cell power generation system according to any one of the first to fifth aspects, The cooling system provides increased cooling capacity for each of the N fuel cells individually.

[0013] An eighth aspect is a fuel cell power generation system according to any one of the first to seventh aspects, The cooling system increases the capacity to cool the kth fuel cell during the first time period more than the capacity to cool the kth fuel cell during the second time period based on input information from the output control device.

[0014] A ninth aspect is the fuel cell power generation system of the eighth aspect, The input information includes operation information related to the output fluctuation operation.

[0015] A tenth aspect is the fuel cell power generation system of the eighth or ninth aspect, The input information includes instruction information regarding adjustment of the cooling capacity of each of the N fuel cells.

[0016] An eleventh aspect is a fuel cell power generation system according to any one of the first to tenth aspects, The cooling system adjusts the capacity of cooling the kth fuel cell by a heat transfer medium.

[0017] A twelfth aspect is the fuel cell power generation system of the eleventh aspect, The cooling system increases the flow rate of the heat medium supplied to the kth fuel cell in the first time period to be greater than the flow rate of the heat medium supplied to the kth fuel cell in the second time period.

[0018] A thirteenth aspect is the fuel cell power generation system of the twelfth aspect, The cooling system includes a common pump that sends the heat medium to the N fuel cells, and the rotation speed of the pump in the first time period is set to be higher than the rotation speed of the pump in the second time period.

[0019] A fourteenth aspect is the fuel cell power generation system of the twelfth aspect, The cooling system is provided for each of the N fuel cells, includes a plurality of pumps for feeding the heat transfer medium to the corresponding fuel cell, and increases the rotation speed of each of the plurality of pumps individually.

[0020] A fifteenth aspect is the fuel cell power generation system of the twelfth aspect, The cooling system includes a common adjustment valve that adjusts the flow rate of the heat transfer medium supplied to the N fuel cells, and the opening degree of the adjustment valve during the first time period is made larger than the opening degree of the adjustment valve during the second time period.

[0021] A sixteenth aspect is the fuel cell power generation system of the twelfth aspect, The cooling system is provided for each of the N fuel cells, and includes a plurality of adjustment valves for adjusting the flow rate of the heat medium supplied to the corresponding fuel cell, and increases the opening degree of each of the adjustment valves individually.

[0022] A seventeenth aspect is the fuel cell power generation system according to any one of the eleventh to sixteenth aspects, The cooling system reduces the temperature of the heat medium supplied to the kth fuel cell in the first time period below the temperature of the heat medium supplied to the kth fuel cell in the second time period.

[0023] An eighteenth aspect is the fuel cell power generation system of the seventeenth aspect, The cooling system includes a fan that supplies air for cooling the heat transfer medium, and the rotation speed of the fan in the first time period is set to be higher than the rotation speed of the fan in the second time period.

[0024] A nineteenth aspect is a fuel cell power generation system according to any one of the first to eighteenth aspects, the kth fuel cell includes a cell stack and an auxiliary device that assists the power generation operation of the cell stack, The cooling system has a greater capacity to cool the cell stack during the first time period than it has a capacity to cool the cell stack during the second time period.

[0025] A 20th aspect is the fuel cell power generation system of the 19th aspect, The cooling system does not increase its ability to cool the accessories during the first time periods more than its ability to cool the accessories during the second time periods.

[0026] A twenty-first aspect is a fuel cell power generation system according to any one of the first to twentieth aspects, The cooling system cools the kth fuel cell by a heat medium circulating between the kth fuel cell and the cooling system, and maintains the temperature of the heat medium output from the kth fuel cell at or above a predetermined temperature.

[0027] A twenty-second aspect is a fuel cell power generation system according to any one of the first to twenty-first aspects, The output fluctuation operation includes a refresh operation of the kth fuel cell.

[0028] A twenty-third aspect is the fuel cell power generation system of the twenty-second aspect, the first time period during which the kth fuel cell performs the refresh operation includes a low load period during which the output power of the kth fuel cell is between 0% and 20% of a maximum output of the kth fuel cell, The cooling system increases its ability to cool the kth fuel cell during the low load period relative to its ability to cool the kth fuel cell during the second time period.

[0029] A twenty-fourth aspect is the fuel cell power generation system of the twenty-second or twenty-third aspect, the first time period during which the kth fuel cell performs the refresh operation includes a low load period during which the output power of the kth fuel cell is either 0% or more and 20% or less of a maximum output of the kth fuel cell, and a high load period during which the output power of the kth fuel cell is either 80% or more and 100% or less of a maximum output of the kth fuel cell, The cooling system reduces its ability to cool the kth fuel cell during the low load periods relative to its ability to cool the kth fuel cell during the high load periods.

[0030] A control method according to a 25th aspect of the present invention includes the steps of: A method for controlling power generation and cooling of N fuel cells, N being an integer equal to or greater than 2, comprising the steps of: performing an output fluctuation operation in which an output power is fluctuated in the N fuel cells; When k is an integer greater than or equal to 1 and less than or equal to N, for the N fuel cells, the capacity to cool the kth fuel cell during a first time period in which the kth fuel cell performs the output fluctuation operation is increased more than the capacity to cool the kth fuel cell during a second time period in which the kth fuel cell does not perform the output fluctuation operation. Effect of the Invention

[0031] According to the present disclosure, energy conservation can be ensured. [Brief description of the drawings]

[0032] [Figure 1] 1 is a block diagram showing an example of the configuration of a fuel cell power generation system according to a first embodiment. [Diagram 2] 4 is a timing chart for explaining one control method for the fuel cell power generation system according to the first and second embodiments. [Diagram 3] FIG. 11 is a block diagram showing an example of the configuration of a fuel cell power generation system according to a second embodiment. [Figure 4] FIG. 11 is a block diagram showing an example of the configuration of a fuel cell power generation system according to a third embodiment. [Diagram 5] 13 is a timing chart for explaining a control method of the fuel cell power generation system according to the third embodiment. [Figure 6] FIG. 13 is a block diagram showing an example of the configuration of a fuel cell power generation system according to a fourth embodiment. [Figure 7] 13 is a timing chart for explaining a control method for the fuel cell power generation system according to the fourth and fifth embodiments. [Figure 8] FIG. 13 is a block diagram showing an example of the configuration of a fuel cell power generation system according to a fifth embodiment. [Figure 9] FIG. 13 is a diagram showing a modification of the cooling system used in the fuel cell power generation system according to the present embodiment. [Figure 10] FIG. 13 is a diagram showing a modification of the cooling system used in the fuel cell power generation system according to the present embodiment. [Figure 11] 13 is a diagram showing a modification of the fuel cell used in the fuel cell power generation system according to the embodiment. FIG. [Figure 12] 13 is a diagram showing a modification of the fuel cell used in the fuel cell power generation system according to the embodiment. FIG. [Figure 13] 13 is a diagram showing a modification of the fuel cell used in the fuel cell power generation system according to the embodiment. FIG. [Figure 14] 13 is a diagram showing a modification of the fuel cell used in the fuel cell power generation system according to the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Several embodiments will be described below.

[0034] In the description of the specification and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals to avoid redundant explanation. For ease of understanding, the scale of each part in the drawings may differ from the actual scale.

[0035] First Embodiment Fig. 1 is a diagram showing an example of the configuration of a fuel cell power generation system according to a first embodiment. The fuel cell power generation system 1 shown in Fig. 1 is a system that supplies electric power Pc generated by N fuel cells (four in this example) to a power supply target (not shown). N is an integer of 2 or more.

[0036] The fuel cell power generation system 1 includes four fuel cells 10a, 10b, 10c, and 10d, an output control device 20, and a cooling system 101. The fuel cell power generation system 1 may include a storage battery 40 or a power conversion device 50.

[0037] Each component of the fuel cell power generation system 1 may be packaged in a package 200. The range of packaging is not limited to the range shown in the figure, and may be changed as appropriate according to specifications and the like.

[0038] Each of the multiple fuel cells 10a, 10b, 10c, and 10d (hereinafter also referred to as "fuel cells 10a, etc.") is a device that generates electricity and heat by a chemical reaction between a fuel such as hydrogen and an oxidant such as oxygen. Each of the fuel cells 10a, etc. has one or more fuel cell cells. Each of the fuel cells 10a, etc. outputs electric power obtained by power generation by one or more fuel cell cells as output power P1, P2, P3, and P4. The fuel cells 10a, etc. are connected in parallel so as to be able to supply power to a common output line 51. The number of multiple fuel cells connected in parallel is not limited to four, and may be two, three, five or more. The fuel cells 10a, etc. may have the same configuration as each other.

[0039] The fuel cells 10a etc. generate electricity by, for example, chemically reacting supplied hydrogen with oxygen contained in the air. The fuel cells 10a etc. may be polymer electrolyte fuel cells (PEFCs), but are not limited to this and may be other types of fuel cells, such as phosphoric acid type.

[0040] Each of the fuel cells 10a, etc., has, for example, a stack structure in which a large number of unit cells are stacked. The unit cell is a fuel cell having a membrane electrode assembly (MEA) and a pair of separators that sandwich the MEA from both sides. The MEA has a polymer electrolyte membrane for selectively transporting hydrogen ions, and a pair of electrodes provided on both sides of the polymer electrolyte membrane. Each of the pair of electrodes is formed of a porous material. Each of the pair of electrodes has, for example, a catalyst layer mainly composed of carbon powder that supports a platinum-based metal catalyst (electrode catalyst), and a gas diffusion layer that has both air permeability and electronic conductivity.

[0041] Each of the fuel cells 10a, etc. may have a boost converter that boosts the power generated by one or more fuel cell cells. Each of the fuel cells 10a, etc. outputs, for example, the power generated by one or more fuel cell cells boosted by the boost converter as output power P1, P2, P3, P4.

[0042] The output control device 20 is a controller that controls power generation of the fuel cell 10a etc. Examples of the output control device 20 include a computer, a programmable logic controller, etc.

[0043] The output control device 20 may acquire each operation data of the fuel cells 10a, etc. For example, the output control device 20 acquires the detection values ​​of each voltage output from the fuel cells 10a, etc. using a voltage sensor, and acquires the detection values ​​of each current output from the fuel cells 10a, etc. using a current sensor. The output control device 20 measures the output powers P1, P2, P3, and P4 of the fuel cells 10a, etc. using the detection values ​​of each voltage and each current.

[0044] The output control device 20 may include a timer for measuring time. For example, the output control device 20 uses a timer to determine whether a predetermined time has elapsed. The output control device 20 may measure time by an interrupt from the timer, or may sequentially refer to the count value of the timer to determine whether the time has elapsed.

[0045] The functions of the output control device 20 (processing performed by the output control device 20) are realized, for example, by a processor such as a CPU (Central Processing Unit) operating according to a program stored in a memory. The functions of the output control device 20 may be realized by a FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0046] The output control device 20 may determine command values ​​(output set values) for the output powers P1, P2, P3, and P4 of the fuel cells 10a, etc. The output control device 20 controls the power generation of the fuel cells 10a, etc., so that the output powers P1, P2, P3, and P4 of the fuel cells 10a, etc., become the corresponding output set values, for example. The output control device 20 may determine command values ​​(output set values) for the output powers P1, P2, P3, and P4 of the fuel cells 10a, etc., in accordance with the power (required output power) required of the fuel cell power generation system 1 as the power to be output to the output line 51.

[0047] The output control device 20 may control the power conversion device 50 interposed in the output line 51 so that a load current corresponding to the required output power flows through the output line 51. For example, the output control device 20 controls the power generation of the fuel cells 10a, etc. so that an amount of air and an amount of hydrogen corresponding to the output current of each of the fuel cells 10a, etc. are supplied to the fuel cells 10a, etc., and the output powers P1, P2, P3, P4 become the corresponding output set values. The output control device 20 is capable of acquiring a measured value of the output current of each of the fuel cells 10a, etc.

[0048] The power conversion device 50 is a device that converts input power Pa into power Pc to be supplied to a power supply target (not shown). The power conversion device 50 is, for example, an inverter that converts DC power obtained by power generation by the fuel cell 10a or the like into AC power and supplies the AC power to the power supply target. Specific examples of inverters include a power conditioner (PCS: Power Conditioning System) and a grid-connected inverter. When the power supply target is a motor, the power conversion device 50 may be an inverter that drives the motor. The power conversion device 50 may be a converter that converts the voltage of the DC power obtained by power generation by the fuel cell 10a or the like into DC power of a different voltage and supplies the DC power to the power supply target.

[0049] The storage battery 40 is charged with DC power obtained by power generation by the fuel cell 10a or the like. Power Pb discharged from the storage battery 40 is supplied to a power supply target via a power conversion device 50. The storage battery 40 may be charged with power input via the power conversion device 50 from an external device such as a power supply target.

[0050] The storage battery 40 may be connected to the fuel cell 10a etc. via a DC / DC converter (not shown). For example, charging or discharging of the storage battery 40 is controlled by the DC / DC converter that operates in response to a drive control signal from the output control device 20.

[0051] Examples of the storage battery 40 include a lithium ion battery, a lithium ion capacitor, and an electric double layer capacitor.

[0052] The fuel cell power generation system 1 outputs electric power Pa which is a sum of output electric powers P1, P2, P3, and P4 of the fuel cells 10a etc. and electric power Pb input / output to / from the storage battery 40. By including the storage battery 40, the fuel cell power generation system 1 can stably output electric power Pa and electric power Pc.

[0053] The output control device 20 may perform control to maintain the electric power Pa or Pc supplied to the outside from the output line 51 at an approximately constant predetermined value. For example, the output control device 20 controls power generation of the fuel cell 10a, etc. so that the electric power Pa or Pc is maintained at a constant target value (an example of required output power).

[0054] The cooling system 101 cools the fuel cell 10a, etc. In this example, the cooling system 101 cools the fuel cell 10a, etc. by a heat medium RF circulating between the cooling device 33 and the fuel cell 10a, etc. The heat medium RF is a fluid for cooling the fuel cell 10a, etc. The heat medium RF is, for example, a coolant such as water.

[0055] The cooling system 101 cools the fuel cell 10a and the like using a heat medium RF (heat medium RF1) supplied from the cooling device 33 through a flow path 34. The cooling system 101 returns the heat medium RF (heat medium RF2) whose temperature has increased after cooling the fuel cell 10a and the like to the cooling device 33 through a flow path 36.

[0056] The cooling system 101 cools the fuel cell 10a and the like by a heat medium RF (heat medium RF1) supplied from a cooling device 33. The fuel cell 10a and the like may be directly cooled by the heat medium RF (heat medium RF1), or may be indirectly cooled by the heat medium RF (heat medium RF1) by being cooled by another heat medium that has exchanged heat with the heat medium RF (heat medium RF1) in a heat exchanger.

[0057] The cooling system 101 includes, for example, a flow path 34, a flow path 36, a cooling device 33, a pump 30, an inverter 31, and a cooling control device 32.

[0058] The flow paths 34 and 36 connect the cooling device 33 to the fuel cell 10a and the like. Each of the flow paths 34 and 36 may be formed by connecting one pipe or a plurality of pipes. For example, the pipes are made of metal such as stainless steel, aluminum, copper, or steel, or resin.

[0059] The flow path 34 carries the heat medium RF1, which is the heat medium RF supplied from the cooling device 33 to the fuel cells 10a, etc. The flow path 34 includes a main flow path 35 connected to the cooling device 33, and N (four in this example) branch flow paths 35a, 35b, 35c, and 35d branching from the main flow path 35. The heat medium RF1 flowing out from the cooling device 33 to the main flow path 35 is supplied to each of the fuel cells 10a, etc. via a corresponding one of the multiple branch flow paths 35a, 35b, 35c, and 35d.

[0060] The flow path 36 is used to carry the heat medium RF2, which is the heat medium RF recovered from the fuel cell 10a etc. to the cooling device 33. The flow path 36 includes a main flow path 37 connected to the cooling device 33, and N (four in this example) branch flow paths 37a, 37b, 37c, 37d branching off from the main flow path 37. The heat medium RF2 flowing out from the fuel cell 10a etc. to the multiple branch flow paths 37a, 37b, 37c, 37d is supplied to the cooling device 33 via the main flow path 37.

[0061] The cooling device 33 supplies the heat medium RF for cooling the fuel cells 10a, etc. (particularly, the fuel cell inside the fuel cell 10a, etc.) to the fuel cells 10a, etc. The cooling device 33 recovers the heat medium RF that has cooled the fuel cells 10a, etc. from the fuel cells 10a, etc., and cools the recovered heat medium RF.

[0062] The cooling device 33 is, for example, a cooling tower. The cooling tower brings the heat medium RF such as cooling water into contact with air, and cools the heat medium RF by the heat of vaporization of the heat medium RF. The cooling method of the cooling device 33 is not limited to this. For example, the cooling device 33 may use cooling water such as seawater, river water, groundwater, pond water, or lake water as the heat medium RF, or may use a heat medium that has been heat exchanged with the cooling water in a heat exchanger as the heat medium RF. The cooling device 33 may pump up cooling water such as seawater, river water, groundwater, pond water, or lake water from a water source such as the sea, river, underground, pond, or lake, and use it as the heat medium RF, or may discharge the cooling water whose temperature has increased by cooling the fuel cell 10a, etc., to a water source.

[0063] The cooling capacity (amount of heat removal) of the cooling device 33 is calculated, for example, by multiplying the total amount of heat removal required for the fuel cells 10a, etc. by a margin (for example, a constant between 1.2 and 1.5). The total amount of heat removal required for the fuel cells 10a, etc. may be the amount of heat removal required at the maximum output of the fuel cells 10a, etc.

[0064] The pump 30 is provided in the main flow path 35 of the flow path 34, and is a common pump that sends the heat medium RF to the N fuel cells 10a, etc. The pump 30 circulates the heat medium RF between the fuel cells 10a, etc. and the cooling device 33. The pump 30 sends the heat medium RF1 that has been cooled and discharged in the cooling device 33 to the fuel cells 10a, etc.

[0065] The inverter 31 is a device for controlling the rotation speed of the pump 30 in accordance with a control signal from the cooling control device 32. For example, the inverter 31 is a drive power supply that controls the rotation speed of the pump 30 by driving a motor in the pump 30 in accordance with a control signal from the cooling control device 32. An example of the inverter 31 is a VVVF inverter that changes the voltage and frequency of an AC drive signal applied to the motor in the pump 30.

[0066] The cooling control device 32 is a controller that controls the ability to cool the fuel cell 10a etc. Examples of the cooling control device 32 include a computer, a programmable logic controller, etc.

[0067] The functions of the cooling control device 32 (processing performed by the cooling control device 32) are realized, for example, by a processor such as a CPU (Central Processing Unit) operating according to a program stored in a memory. The functions of the cooling control device 32 may be realized by a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC).

[0068] The cooling control device 32 may be a controller integrated with the output control device 20 or may be a controller separate from the output control device 20.

[0069] Next, an example of a method for controlling power generation and cooling of the fuel cell power generation system 1 according to the first embodiment will be described in detail.

[0070] The output control device 20 controls the power generation of N fuel cells 10a, etc. (four in this example). The output control device 20 causes the N fuel cells 10a, etc. to perform a predetermined output fluctuation operation (hereinafter also referred to as "output fluctuation operation D") that fluctuates the output power. For example, the output control device 20 causes the fuel cell 10a to perform the output fluctuation operation D that fluctuates the output power P1. Similarly, the output control device 20 causes the fuel cells 10b, 10c, 10d to perform the output fluctuation operation D that fluctuates the corresponding output power among the output powers P2, P3, P4.

[0071] The cooling control device 32 controls the cooling of the N fuel cells 10a, etc. The cooling control device 32 increases the capacity to cool the k-th fuel cell during a first time period in which the k-th fuel cell performs output fluctuation operation D, for the N fuel cells 10a, etc., more than the capacity to cool the k-th fuel cell during a second time period in which the k-th fuel cell does not perform output fluctuation operation D. k is an integer between 1 and N. The cooling control device 32 executes capacity variable control to increase the capacity to cool the k-th fuel cell in this manner for all of the N fuel cells 10a, etc.

[0072] In the following description, the first time period during which the kth fuel cell performs the output fluctuation operation D will be referred to as the "first time period Z1," and the second time period during which the kth fuel cell does not perform the output fluctuation operation D will be referred to as the "second time period Z2."

[0073] Due to the variable capacity control, the capacity to cool the kth fuel cell in a first time zone Z1 when the kth fuel cell performs the output fluctuation operation D is higher than the capacity to cool the kth fuel cell in a second time zone Z2 when the kth fuel cell does not perform the output fluctuation operation D. Therefore, even if the output power of the kth fuel cell fluctuates (especially increases sharply) in the first time zone Z1 due to the output fluctuation operation D, the possibility that the capacity to cool the kth fuel cell will be insufficient in the first time zone Z1 is reduced, and the capacity to cool the kth fuel cell is ensured. By ensuring the capacity to cool the kth fuel cell, for example, an excessive temperature rise in the kth fuel cell is suppressed, and the temperature in the kth fuel cell is suppressed from exceeding a predetermined constraint temperature.

[0074] On the other hand, due to the variable capacity control, the capacity to cool the kth fuel cell in the second time zone Z2 when the kth fuel cell is not performing the output fluctuation operation D is lower than the capacity to cool the kth fuel cell in the first time zone Z1 when the kth fuel cell performs the output fluctuation operation D. This improves the energy conservation of the fuel cell power generation system 1 compared to a case where the capacity to cool the kth operating fuel cell is always provided with a margin throughout the first time zone Z1 and the second time zone Z2.

[0075] In this way, with variable capacity control, it is possible to ensure both the capacity to cool the N fuel cells 10a etc. and the energy saving properties of the fuel cell power generation system 1.

[0076] In the cooling system 101 according to the first embodiment, the cooling control device 32 increases the flow rate of the heat transfer medium RF supplied to the k-th fuel cell in the first time zone Z1 to be greater than the flow rate of the heat transfer medium RF supplied to the k-th fuel cell in the second time zone Z2. This achieves variable capacity control. Specifically, the cooling control device 32 achieves variable capacity control by making the rotation speed of the pump 30 in the first time zone Z1 higher than the rotation speed of the pump 30 in the second time zone Z2.

[0077] By the capacity variable control according to the first embodiment, the rotation speed of the pump 30 in the first time zone Z1 is higher than the rotation speed of the pump 30 in the second time zone Z2. As a result, the flow rate of the heat transfer medium RF supplied to the kth fuel cell in the first time zone Z1 is higher than the flow rate of the heat transfer medium RF supplied to the kth fuel cell in the second time zone Z2. Therefore, the capacity to cool the kth fuel cell in the first time zone Z1 is higher than the capacity to cool the kth fuel cell in the second time zone Z2. Therefore, even if the output power of the kth fuel cell fluctuates (especially increases sharply) in the first time zone Z1 due to the output fluctuation operation D, the capacity to cool the kth fuel cell is ensured. On the other hand, the rotation speed of the pump 30 in the second time zone Z2 is lower than the rotation speed of the pump 30 in the first time zone Z1, so the energy saving of the pump 30 is improved compared to the case where the rotation speed of the pump 30 is always set high throughout the first time zone Z1 and the second time zone Z2.

[0078] In the cooling system 101 according to the first embodiment, the cooling control device 32 collectively increases the capacity to cool each of the N fuel cells 10a, etc. by increasing the rotation speed of the pump 30 that can adjust the flow rate of the heat medium RF flowing through the main flow path 35. Meanwhile, the cooling control device 32 collectively decreases the capacity to cool each of the N fuel cells 10a, etc. by decreasing the rotation speed of the pump 30 that can adjust the flow rate of the heat medium RF flowing through the main flow path 35. Since the capacity to cool each of the N fuel cells 10a, etc. is collectively adjusted by the pump 30 that is common to the N fuel cells 10a, etc., the configuration for adjusting the capacity to cool each of the N fuel cells 10a, etc. can be simplified.

[0079] In the cooling system 101 according to the first embodiment, the cooling control device 32 may increase the capacity to cool the k-th fuel cell in the first time zone Z1 more than the capacity to cool the k-th fuel cell in the second time zone Z2, based on the input information A from the output control device 20. By acquiring the input information A from the output control device 20, the cooling control device 32 can accurately identify the time zone during which the output control device 20 causes the fuel cell 10a, etc. to perform the output variable operation D. Therefore, the cooling control device 32 can execute capacity variable control in an accurate time zone including the first time zone Z1.

[0080] The input information A may include operation information related to the output fluctuation operation D of each of the N fuel cells 10a, etc. The operation information is, for example, information that enables the cooling control device 32 to determine whether or not the output control device 20 is performing the output fluctuation operation D. Specific examples of the operation information include the length of the time period during which the output fluctuation operation D is performed, time information such as the start time or end time, and flag information indicating whether or not the output fluctuation operation D is being performed.

[0081] The input information A may include instruction information regarding adjustment of the capacity to cool each of the N fuel cells 10a, etc. The instruction information is, for example, information for determining whether or not the cooling control device 32 executes capacity variable control. A specific example of the instruction information is a signal from the output control device 20 to the cooling control device 32 to execute capacity variable control.

[0082] 2 is a timing chart for explaining one control method of the fuel cell power generation system according to the first embodiment (and the second embodiment described below). Output powers P1, P2, P3, and P4 represent the output powers of the fuel cells 10a, 10b, 10c, and 10d, respectively. Flow rates Q1, Q2, Q3, and Q4 represent the flow rates of the heat transfer medium RF (heat transfer medium RF flowing through the branch flow paths 35a, 35b, 35c, and 35d) supplied to the fuel cells 10a, 10b, 10c, and 10d, respectively.

[0083] The output control device 20 performs the output fluctuation operation D in the order of fuel cell 10a, fuel cell 10b, fuel cell 10c, and fuel cell 10d during time period t2-t7. When the output fluctuation operation D is performed in each fuel cell, the output powers P1, P2, P3, and P4 during the output fluctuation operation D temporarily fluctuate greatly. On the other hand, the fuel cell power generation system 1 may be required to maintain the power Pa or the power Pc at a constant value.

[0084] Therefore, as shown in Fig. 2, the output control device 20 switches the fuel cell performing the output fluctuation operation D in the order of fuel cell 10a, fuel cell 10b, fuel cell 10c, and fuel cell 10d. This maintains the electric power Pa or electric power Pc at a constant value. The output control device 20 distributes the electric power generated by the fuel cell performing the output fluctuation operation D to the other fuel cells not performing the output fluctuation operation D, thereby enabling the fuel cell power generation system 1 to maintain the electric power Pa or electric power Pc at a constant value.

[0085] The time zone t2-t7 corresponds to a time zone in which one or more of the N fuel cells 10a etc. perform the output fluctuation operation D. The time zone Z21 before time t1 or the time zone Z22 after time t8 corresponds to a time zone in which none of the N fuel cells 10a etc. perform the output fluctuation operation D. The time zone Z21 or the time zone Z22 is an example of a second time zone Z2 in which the k-th fuel cell does not perform the output fluctuation operation D. The time zone from time t2 to time t7 or the specific time zone Z1a from time t2 to time t3 is an example of a first time zone Z1 in which the fuel cell 10a performs the output fluctuation operation D. The time zone from time t2 to time t7 or the specific time zone Z1b from time t3 to time t4 is an example of a first time zone Z1 in which the fuel cell 10b performs the output fluctuation operation D. The time zone from time t2 to time t7 or the specific time zone Z1c from time t4 to time t5 is an example of a first time zone Z1 in which the fuel cell 10c performs the output fluctuation operation D. The time period from time t2 to time t7 or the specific time period Z1d from time t5 to time t7 is an example of a first time period Z1 during which the fuel cell 10a performs the output fluctuation operation D.

[0086] In the cooling system 101 according to the first embodiment, the cooling control device 32 increases the capacity to cool each of the N fuel cells 10a, etc. during time period t2-t7, more than the capacity during time period Z21 or time period Z22. Specifically, the cooling control device 32 increases the flow rate qu of the heat transfer medium RF supplied to the fuel cell 10a during time period t2-t7, including time period Z1a, more than the flow rate qd of the heat transfer medium RF supplied to the fuel cell 10a during time period Z21 or time period Z22. This realizes variable capacity control. Similar variable capacity control is realized for the other fuel cells 10b, 10c, 10d.

[0087] In the cooling system 101 according to the first embodiment, the cooling control device 32 may increase the capacity to cool the k-th fuel cell from before the first time zone Z1 in which the k-th fuel cell performs the output fluctuation operation D. This makes it possible to increase the capacity to cool the k-th fuel cell as much as possible at the start of the first time zone Z1. This reduces the possibility that the capacity to cool the k-th fuel cell at the start of the first time zone Z1 will be insufficient due to an operational delay in the cooling system 101.

[0088] 2, the cooling control device 32 increases the capacity to cool the fuel cell 10a from time t1, which is before the time period t2-t7 including the time period Z1a. The cooling control device 32 similarly increases the capacity to cool each of the other fuel cells 10b, 10c, and 10d. The period from time t1 to time t2 is, for example, anywhere from 1 minute to 10 minutes, and preferably 2 minutes.

[0089] In the cooling system 101 according to the first embodiment, the cooling control device 32 may increase the capacity to cool the kth fuel cell until after the first time zone Z1 during which the kth fuel cell performs the output fluctuation operation D. This makes it possible to increase the capacity to cool the kth fuel cell as much as possible at the end of the first time zone Z1. This reduces the possibility that the capacity to cool the kth fuel cell will be insufficient midway through the first time zone Z1. The period from time t7 to time t8 is, for example, 1 minute to 10 minutes, preferably 2 minutes.

[0090] The output varying operation D may be an operation in which the output power varies according to a predetermined variation pattern, and may include, for example, a refresh operation that improves the characteristics of the kth fuel cell.

[0091] For example, as the first refresh operation, the fuel cell power generation system 1 may change the output powers P1, P2, P3, and P4 of the fuel cell 10a, etc., in the order of high output, low output, and high output, respectively. In other words, as the first refresh operation, the fuel cell power generation system 1 may change the loads on the fuel cell 10a, etc., in the order of high load, low load, and high load. In the first refresh operation, the fuel cell power generation system 1 may continue to supply hydrogen and air to the fuel cell 10a, etc. without stopping.

[0092] As a representative example, an example of the flow of the refresh process in the first refresh operation of the fuel cell 10a will be described below.

[0093] The output control device 20 sets the output setting of the fuel cell 10a to a predetermined output setting. To explain using the example of Fig. 2, the output control device 20 sets the output of the fuel cell 10a to an output pr which is a predetermined setting.

[0094] Next, the output control device 20 sets the output setting of the fuel cell 10a to the high output setting, and then the output control device 20 maintains the output setting of the fuel cell 10a at the high output setting for a certain period of time.

[0095] Explaining using the example of FIG. 2, at time t2, the output control device 20 sets the output of the fuel cell 10a to an output pu, which is a high output setting. For example, assuming that the maximum output power of the fuel cell 10a is 100%, the high output setting is an output power anywhere between 80% and 100%. The output control device 20 maintains the output setting of the fuel cell 10a at the high output setting during a period z1. The period z1 is, for example, anywhere between 10 seconds and 3 minutes, preferably 1 minute.

[0096] In the fuel cell power generation system 1, by temporarily performing high output operation (high load operation), the amount of moisture inside the fuel cell is increased by water generated by power generation.

[0097] Next, the output control device 20 sets the output setting of the fuel cell 10a to a low output setting, and then the output control device 20 maintains the output setting of the fuel cell 10a at the low output setting for a certain period of time.

[0098] Explaining using the example of FIG. 2, the output control device 20 sets the output of the fuel cell 10a to a low output setting, output pd. For example, the low output setting is an output power between 0% and 20% of the maximum output power of the fuel cell 10a, which is taken as 100%. The output control device 20 maintains the output setting of the fuel cell 10a at the low output setting during a period z2. The period z2 is, for example, between 10 seconds and 3 minutes, preferably 1 minute.

[0099] In the fuel cell power generation system 1, by performing a high-output operation (high-load operation) and then a low-output operation (low-load operation), the water generated by power generation is made uniform on the surface of the fuel cell.

[0100] Next, the output control device 20 sets the output setting of the fuel cell 10a to the high output setting, and then the output control device 20 maintains the output setting of the fuel cell 10a at the high output setting for a certain period of time.

[0101] To explain using the example of Fig. 2, the output control device 20 sets the output of the fuel cell 10a to an output pu, which is a high output setting. For example, if the maximum output power of the fuel cell 10a is 100%, the high output setting is an output power between 80% and 100%. During a period z3, the output control device 20 maintains the output setting of the fuel cell 10a at the high output setting. The period z3 is, for example, between 10 seconds and 3 minutes, preferably 1 minute.

[0102] In the fuel cell power generation system 1, the moisture content in the fuel cell is increased again by sequentially performing high power operation (high load operation), low power operation (low load operation), and high power operation (high load operation). By increasing the moisture content in the fuel cell, it is possible to moisten dry areas within the surface of the fuel cell that have been dried by performing continuous operation. By moistening the dry areas within the surface of the fuel cell, it is possible to suppress deterioration of the battery characteristics of the fuel cell.

[0103] The supply of hydrogen and oxygen to the fuel cell 10a may be continued during the first refresh operation in the fuel cell power generation system 1. By continuing the supply of hydrogen and oxygen to the fuel cell 10a, deterioration of the fuel cell unit due to a lack of oxygen can be suppressed.

[0104] The first refresh operation of each of the other fuel cells 10b, 10c, and 10d may be performed in the same manner as the above-mentioned refresh process of the fuel cell 10a.

[0105] It should be noted that the fluctuation pattern of the output power in the refresh operation is not limited to the pattern in the first refresh operation.

[0106] For example, as a modification of the first refresh operation, the fuel cell power generation system 1 may change the output powers P1, P2, P3, and P4 of the fuel cells 10a, etc., in the order of low output, high output, and low output, respectively. In other words, as a modification of the first refresh operation, the fuel cell power generation system 1 may change the loads on the fuel cells 10a, etc., in the order of low load, high load, and low load. Even in the modification of the first refresh operation, the fuel cell power generation system 1 may continue to supply hydrogen and air to the fuel cells 10a, etc. without stopping.

[0107] Alternatively, as the second refresh operation, the fuel cell power generation system 1 may stop the operation of the fuel cell 10a, etc., and then restart them. In the second refresh operation, the fuel cell power generation system 1 may stop the supply of hydrogen and air to the fuel cell 10a, etc., while the fuel cell 10a is stopped.

[0108] 2, the first time zone Z1 during which the kth fuel cell performs the refresh operation includes a period z2 as a low-load period during which the output power of the kth fuel cell is between 0% and 20% of the maximum output of the kth fuel cell. Period z2 is not limited to a low-load period during the first refresh operation, and may be a period during which the fuel cell is out of operation during the second refresh operation.

[0109] In the cooling system 101 according to the first embodiment, the cooling control device 32 may continue cooling the fuel cell 10a, etc. during period z2 without stopping it, as shown in Fig. 2. This reduces the possibility that the capacity to cool the fuel cell 10a, etc. will be insufficient after period z2 due to a delay from stopping to restarting the cooling system 101, for example, when period z2 is relatively short.

[0110] 2, the cooling control device 32 increases the flow rate qu of the heat transfer medium RF supplied to the kth fuel cell over periods z1, z2, and z3 to be greater than the flow rate qd of the heat transfer medium RF supplied to the fuel cell 10a in time zone Z21 or time zone Z22. As a result, the capacity to cool the kth fuel cell over periods z1, z2, and z3 is greater than the capacity to cool the kth fuel cell in time zone Z21 or time zone Z22, and cooling of the fuel cells 10a, etc. continues without stopping during period z2.

[0111] In the example shown in Figure 2, the first time zone Z1 during which the kth fuel cell performs refresh operation includes period z1 or period z3 as a high load period during which the output power of the kth fuel cell is either 80% or more and 100% or less of the maximum output of the kth fuel cell.

[0112] In the cooling system 101 according to the first embodiment, the cooling control device 32 may suppress or stop the cooling of the fuel cell 10a, etc., during the period z2, although this is not particularly shown. This improves the energy saving performance of the pump 30 and the inverter 31. For example, the cooling control device 32 suppresses or stops the rotation of the pump 30 during the period z2, thereby reducing the flow rate of the heat medium RF supplied to the k-th fuel cell during the period z2 to be lower than the flow rate of the heat medium RF supplied to the fuel cell 10a during the period z1 or the period z3 (particularly, reducing it to zero). As a result, the capacity to cool the k-th fuel cell during the period z2 is lower than the capacity to cool the k-th fuel cell during the period z1 or the period z3, and the cooling of the fuel cell 10a, etc. is suppressed or stopped during the period z2.

[0113] Second Embodiment 3 is a diagram showing a configuration example of a fuel cell power generation system according to the second embodiment. In the second embodiment, the description of the configuration, operation, and effects similar to those of the first embodiment will be omitted by citing the above description.

[0114] The fuel cell power generation system 2 according to the second embodiment differs from the fuel cell power generation system 1 according to the first embodiment in that it includes an adjustment valve 38. The fuel cell power generation system 2 includes a cooling system 102 that cools the fuel cell 10a and the like, similar to the above-mentioned cooling system 101. The cooling system 102 includes an adjustment valve 38. The cooling system 102 does not include the above-mentioned inverter 31 for controlling the rotation speed of the pump 30. However, the cooling system 102 may include the inverter 31 so as to obtain the same functions and effects as those of the first embodiment.

[0115] The adjustment valve 38 is provided in the main flow path 35 of the flow path 34, and is a common adjustment valve that adjusts the flow rate of the heat transfer medium RF supplied to the N fuel cells 10a, etc. The adjustment valve 38 adjusts the flow rate of the heat transfer medium RF circulating between the fuel cells 10a, etc. and the cooling device 33. The adjustment valve 38 is provided, for example, at the inlet of the heat transfer medium RF in the package 200. An example of the adjustment valve 38 is an electrically operated adjustment valve.

[0116] Next, an example of a method for controlling power generation and cooling of the fuel cell power generation system 2 according to the second embodiment will be described in detail.

[0117] In the cooling system 102 according to the second embodiment, the cooling control device 32 increases the flow rate of the heat transfer medium RF supplied to the k-th fuel cell in the first time zone Z1 more than the flow rate of the heat transfer medium RF supplied to the k-th fuel cell in the second time zone Z2. This achieves variable capacity control. Specifically, the cooling control device 32 achieves variable capacity control by making the opening degree of the adjustment valve 38 in the first time zone Z1 larger than the opening degree of the adjustment valve 38 in the second time zone Z2.

[0118] By the capacity variable control according to the second embodiment, the opening degree of the regulator valve 38 in the first time zone Z1 is larger than the opening degree of the regulator valve 38 in the second time zone Z2. As a result, the flow rate of the heat transfer medium RF supplied to the kth fuel cell in the first time zone Z1 is greater than the flow rate of the heat transfer medium RF supplied to the kth fuel cell in the second time zone Z2. Therefore, the capacity to cool the kth fuel cell in the first time zone Z1 is higher than the capacity to cool the kth fuel cell in the second time zone Z2. Therefore, even if the output power of the kth fuel cell fluctuates (especially increases sharply) due to the output fluctuation operation D in the first time zone Z1, the capacity to cool the kth fuel cell is ensured. On the other hand, the opening degree of the regulator valve 38 in the second time zone Z2 is smaller than the opening degree of the regulator valve 38 in the first time zone Z1, so the flow rate of the heat transfer medium RF supplied to the kth fuel cell in the second time zone Z2 is smaller than the flow rate of the heat transfer medium RF supplied to the kth fuel cell in the first time zone Z1. Therefore, the energy saving performance of the pump 30 is improved compared to when the opening degree of the adjustment valve 38 is always set large throughout the first time zone Z1 and the second time zone Z2.

[0119] In the cooling system 102 according to the second embodiment, the cooling control device 32 collectively increases the capacity to cool each of the N fuel cells 10a, etc. by increasing the aperture of the adjustment valve 38 that can adjust the flow rate of the heat medium RF flowing through the main flow path 35. Meanwhile, the cooling control device 32 collectively decreases the capacity to cool each of the N fuel cells 10a, etc. by decreasing the aperture of the adjustment valve 38 that can adjust the flow rate of the heat medium RF flowing through the main flow path 35. Since the capacity to cool each of the N fuel cells 10a, etc. is collectively adjusted by the adjustment valve 38 common to the N fuel cells 10a, etc., the configuration for adjusting the capacity to cool each of the N fuel cells 10a, etc. can be simplified.

[0120] In the second embodiment, the cooling control device 32 may, similar to the first embodiment, increase the capacity to cool the kth fuel cell in the first time zone Z1 more than the capacity to cool the kth fuel cell in the second time zone Z2 based on input information A from the output control device 20.

[0121] The timing chart for illustrating one control method for the fuel cell power generation system according to the second embodiment will not be described here since the above description of FIG. 2 is incorporated herein by reference.

[0122] Third Embodiment 4 is a diagram showing a configuration example of a fuel cell power generation system according to the third embodiment. In the third embodiment, the description of the configuration, operation, and effects similar to those of the first embodiment will be omitted by citing the above description.

[0123] The fuel cell power generation system 3 according to the third embodiment differs from the fuel cell power generation system 1 according to the first embodiment in that it includes a fan 33a and an inverter 39. The fuel cell power generation system 3 includes a cooling system 103 that cools the fuel cell 10a and the like, similar to the above-mentioned cooling system 101. The cooling system 103 includes a fan 33a and an inverter 39. The cooling system 103 does not include the above-mentioned inverter 31 for controlling the rotation speed of the pump 30. However, the cooling system 103 may include the inverter 31 so as to obtain the same actions and effects as those of the first embodiment.

[0124] The fan 33a is a rotating body that supplies air to cool the heat medium RF. As the rotation speed of the fan 33a increases, the volume of air supplied from the fan 33a increases, so the temperature of the heat medium RF decreases, or the temperature rise of the heat medium RF is suppressed. As the rotation speed of the fan 33a decreases, the volume of air supplied from the fan 33a decreases, so the temperature of the heat medium RF increases, or the temperature drop of the heat medium RF is suppressed.

[0125] The inverter 39 is a device for controlling the rotation speed of the fan 33a in accordance with a control signal from the cooling control device 32. For example, the inverter 39 is a drive power supply that controls the rotation speed of the fan 33a by driving a motor that rotates the fan 33a in accordance with a control signal from the cooling control device 32. An example of the inverter 39 is a VVVF inverter that changes the voltage and frequency of an AC drive signal applied to the motor that rotates the fan 33a.

[0126] Next, an example of a method for controlling power generation and cooling of the fuel cell power generation system 3 according to the third embodiment will be described in detail.

[0127] In the cooling system 103 according to the third embodiment, the cooling control device 32 reduces the temperature of the heat transfer medium RF supplied to the k-th fuel cell in the first time zone Z1 to be lower than the temperature of the heat transfer medium RF supplied to the k-th fuel cell in the second time zone Z2. This achieves variable capacity control. Specifically, the cooling control device 32 achieves variable capacity control by making the rotation speed of the fan 33a in the first time zone Z1 higher than the rotation speed of the fan 33a in the second time zone Z2.

[0128] By the variable capacity control according to the third embodiment, the rotation speed of the fan 33a in the first time zone Z1 is higher than the rotation speed of the fan 33a in the second time zone Z2. As a result, the temperature of the heat medium RF supplied to the kth fuel cell in the first time zone Z1 is lower than the temperature of the heat medium RF supplied to the kth fuel cell in the second time zone Z2. Therefore, the capacity to cool the kth fuel cell in the first time zone Z1 is higher than the capacity to cool the kth fuel cell in the second time zone Z2. Therefore, even if the output power of the kth fuel cell fluctuates (especially increases sharply) in the first time zone Z1 due to the output fluctuation operation D, the capacity to cool the kth fuel cell is ensured. On the other hand, the rotation speed of the fan 33a in the second time zone Z2 is lower than the rotation speed of the fan 33a in the first time zone Z1, so the energy saving of the fan 33a is improved compared to the case where the rotation speed of the fan 33a is always set high throughout the first time zone Z1 and the second time zone Z2.

[0129] In the cooling system 103 according to the third embodiment, the cooling control device 32 collectively increases the capacity to cool each of the N fuel cells 10a, etc. by increasing the rotation speed of the fan 33a that can adjust the temperature of the heat medium RF flowing through the main flow path 35. On the other hand, the cooling control device 32 collectively decreases the capacity to cool each of the N fuel cells 10a, etc. by decreasing the rotation speed of the fan 33a that can adjust the temperature of the heat medium RF flowing through the main flow path 35. Since the capacity to cool each of the N fuel cells 10a, etc. is collectively adjusted by the fan 33a that is common to the N fuel cells 10a, etc., the configuration for adjusting the capacity to cool each of the N fuel cells 10a, etc. can be simplified.

[0130] In the third embodiment, the cooling control device 32 may, similar to the first embodiment, increase the capacity to cool the kth fuel cell in the first time zone Z1 more than the capacity to cool the kth fuel cell in the second time zone Z2 based on input information A from the output control device 20.

[0131] 5 is a timing chart for explaining one control method of the fuel cell power generation system according to the third embodiment. Output powers P1, P2, P3, and P4 represent the output powers of the fuel cells 10a, 10b, 10c, and 10d, respectively. Temperatures T1, T2, T3, and T4 represent the temperatures of the heat transfer medium RF (heat transfer medium RF flowing through the branch paths 35a, 35b, 35c, and 35d) supplied to the fuel cells 10a, 10b, 10c, and 10d, respectively.

[0132] In the cooling system 103 according to the third embodiment, the cooling control device 32 increases the capacity to cool each of the N fuel cells 10a, etc. during time period t2-t7 more than the capacity during time period Z21 or time period Z22. Specifically, the cooling control device 32 reduces the temperature td of the heat medium RF supplied to the fuel cell 10a during time period Z1a when the fuel cell 10a performs the output fluctuation operation D to less than the temperature tu of the heat medium RF supplied to the fuel cell 10a during time period Z21 or Z22 when the fuel cell 10a does not perform the output fluctuation operation D. This realizes variable capacity control. Similar variable capacity control is realized for the other fuel cells 10b, 10c, 10d.

[0133] In the third embodiment, similar to the first embodiment, the cooling control device 32 may increase the capacity to cool the kth fuel cell from before the first time zone Z1 during which the kth fuel cell performs the output fluctuation operation D. In the third embodiment, similar to the first embodiment, the cooling control device 32 may increase the capacity to cool the kth fuel cell from after the first time zone Z1 during which the kth fuel cell performs the output fluctuation operation D.

[0134] In the cooling system 103 according to the third embodiment, the cooling control device 32 may continue cooling the fuel cell 10a, etc. during period z2 without stopping it, as shown in Fig. 5. This reduces the possibility that the capacity to cool the fuel cell 10a, etc. will be insufficient after period z2 due to a delay from stopping the cooling system 103 to restarting it, for example, when period z2 is relatively short.

[0135] 5, the cooling control device 32 reduces the temperature td of the heat transfer medium RF supplied to the kth fuel cell over periods z1, z2, and z3 to be lower than the temperature tu of the heat transfer medium RF supplied to the fuel cell 10a in time zone Z21 or time zone Z22. As a result, the capacity to cool the kth fuel cell over periods z1, z2, and z3 is greater than the capacity to cool the kth fuel cell in time zone Z21 or time zone Z22, and cooling of the fuel cells 10a, etc. continues without stopping during period z2.

[0136] In the cooling system 103 according to the third embodiment, the cooling control device 32 may suppress or stop the cooling of the fuel cell 10a, etc., during the period z2, although this is not particularly shown. This improves the energy saving performance of the fan 33a and the inverter 39. For example, the cooling control device 32 suppresses or stops the rotation of the fan 33a during the period z2, thereby raising the temperature of the heat medium RF supplied to the kth fuel cell during the period z2 to a temperature higher than the temperature of the heat medium RF supplied to the fuel cell 10a during the period z1 or the period z3. As a result, the capacity to cool the kth fuel cell during the period z2 is lower than the capacity to cool the kth fuel cell during the period z1 or the period z3, and the cooling of the fuel cell 10a, etc. is suppressed or stopped during the period z2.

[0137] Fourth Embodiment 6 is a diagram showing a configuration example of a fuel cell power generation system according to the fourth embodiment. In the fourth embodiment, the description of the configuration, operation, and effects similar to those of the first embodiment will be omitted by citing the above description.

[0138] The fuel cell power generation system 4 according to the fourth embodiment differs from the fuel cell power generation system 1 according to the first embodiment in that it includes a plurality of pumps 30a, 30b, 30c, 30d and a plurality of inverters 31a, 31b, 31c, 31d. The fuel cell power generation system 4 includes a cooling system 104 that cools the fuel cell 10a etc., similar to the cooling system 101 described above.

[0139] A plurality of pumps 30a, 30b, 30c, and 30d are provided for each of the N fuel cells 10a to send the heat transfer medium RF to the corresponding fuel cell. The pumps 30a, 30b, 30c, and 30d are provided in the branch flow paths 35a, 35b, 35c, and 35d, respectively.

[0140] The multiple inverters 31a, 31b, 31c, and 31d are devices for controlling the rotation speed of the pumps 30a, 30b, 30c, and 30d according to a control signal from the cooling control device 32. For example, the inverter 31a is a drive power source that controls the rotation speed of the pump 30a by driving the motor in the pump 30a according to a control signal from the cooling control device 32. An example of the inverter 31a is a VVVF inverter that changes the voltage and frequency of an AC drive signal applied to the motor in the pump 30a. The other inverters 31b, 31c, and 31d also drive the pumps 30b, 30c, and 30d in the same way as the inverter 31a.

[0141] Next, an example of a method for controlling power generation and cooling of the fuel cell power generation system 4 according to the fourth embodiment will be described in detail.

[0142] In the cooling system 104 according to the fourth embodiment, the cooling control device 32 increases the flow rate of the heat transfer medium RF supplied to the k-th fuel cell in the first time zone Z1 to be greater than the flow rate of the heat transfer medium RF supplied to the k-th fuel cell in the second time zone Z2. This achieves variable capacity control. Specifically, the cooling control device 32 achieves variable capacity control by making the rotation speed of the pump 30a in the first time zone Z1 higher than the rotation speed of the pump 30a in the second time zone Z2. The cooling control device 32 achieves variable capacity control by also making the rotation speeds of the other pumps 30b, 30c, and 30d higher in the same manner as the pump 30a.

[0143] In the cooling system 104 according to the fourth embodiment, the cooling control device 32 individually increases the rotation speed of each of the pumps 30a, 30b, 30c, 30d to individually increase the cooling capacity of each of the N fuel cells 10a, etc. As a result, the flow rate of the heat medium RF flowing through each of the pumps 30a, 30b, 30c, 30d is reduced compared to the case where the cooling capacity of each of the N fuel cells 10a, etc. is increased collectively, improving the energy saving performance of each of the pumps 30a, 30b, 30c, 30d.

[0144] In the cooling system 104 according to the fourth embodiment, the cooling control device 32 may increase the rotation speed of each of the pumps 30a, 30b, 30c, and 30d collectively to thereby increase the cooling capacity of each of the N fuel cells 10a, etc. collectively.

[0145] In the fourth embodiment, the cooling control device 32 may, similarly to the first embodiment, increase the capacity to cool the kth fuel cell in the first time zone Z1 more than the capacity to cool the kth fuel cell in the second time zone Z2 based on input information A from the output control device 20.

[0146] 7 is a timing chart for explaining one control method of the fuel cell power generation system according to the fourth embodiment (and the fifth embodiment described below). Output powers P1, P2, P3, and P4 represent the output powers of the fuel cells 10a, 10b, 10c, and 10d, respectively. Flow rates Q1, Q2, Q3, and Q4 represent the flow rates of the heat transfer medium RF (heat transfer medium RF flowing in the branch flow paths 35a, 35b, 35c, and 35d) supplied to the fuel cells 10a, 10b, 10c, and 10d, respectively.

[0147] In the cooling system 104 according to the fourth embodiment, the cooling control device 32 increases the rotation speed of each of the multiple pumps 30a, 30b, 30c, and 30d individually, thereby individually increasing the cooling capacity of each of the N fuel cells 10a, etc.

[0148] In the cooling system 104 according to the fourth embodiment, the cooling control device 32 increases the flow rate qu of the heat transfer medium RF supplied to the fuel cell 10a in the time zone Z1a to be greater than the flow rate qd of the heat transfer medium RF supplied to the fuel cell 10a in the time zone Z21 or the time zone Z22. This realizes variable capacity control. The same variable capacity control is also realized for the other fuel cells 10b, 10c, and 10d.

[0149] Fifth embodiment 8 is a diagram showing a configuration example of a fuel cell power generation system according to the fifth embodiment. In the fifth embodiment, the description of the configuration, operation, and effects similar to those of the first embodiment will be omitted by citing the above description.

[0150] The fuel cell power generation system 5 according to the fifth embodiment differs from the fuel cell power generation system 1 according to the first embodiment in that it includes a plurality of adjustment valves 38a, 38b, 38c, and 38d. The fuel cell power generation system 5 includes a cooling system 105 that cools the fuel cell 10a and the like, similar to the cooling system 101 described above.

[0151] The multiple adjustment valves 38a, 38b, 38c, and 38d are provided for each of the N fuel cells 10a to adjust the flow rate of the heat transfer medium RF supplied to the corresponding fuel cell. The adjustment valves 38a, 38b, 38c, and 38d are provided in the branch paths 35a, 35b, 35c, and 35d, respectively.

[0152] Next, an example of a method for controlling power generation and cooling of the fuel cell power generation system 5 according to the fifth embodiment will be described in detail.

[0153] In the cooling system 105 according to the fifth embodiment, the cooling control device 32 increases the flow rate of the heat transfer medium RF supplied to the k-th fuel cell in the first time zone Z1 more than the flow rate of the heat transfer medium RF supplied to the k-th fuel cell in the second time zone Z2. This realizes variable capacity control. Specifically, the cooling control device 32 realizes variable capacity control by making the opening degree of the regulator valve 38a in the first time zone Z1 larger than the opening degree of the regulator valve 38a in the second time zone Z2. The cooling control device 32 realizes variable capacity control by also making the opening degrees of the other regulator valves 38b, 38c, 38d larger in the same manner as the regulator valve 38a.

[0154] In the cooling system 105 according to the fifth embodiment, the cooling control device 32 individually increases the opening of each of the adjustment valves 38a, 38b, 38c, 38d to individually increase the cooling capacity of each of the N fuel cells 10a, etc. This reduces the flow rate of the heat transfer medium RF flowing through the pump 30 compared to the case where the cooling capacity of each of the N fuel cells 10a, etc. is increased collectively, thereby improving the energy saving performance of the pump 30.

[0155] In the cooling system 105 of the fifth embodiment, the cooling control device 32 may increase the capacity to cool each of the N fuel cells 10a, etc., all at once by simultaneously increasing the opening degree of each of the adjustment valves 38a, 38b, 38c, and 38d.

[0156] In the fifth embodiment, the cooling control device 32 may, similar to the first embodiment, increase the capacity to cool the kth fuel cell in the first time zone Z1 more than the capacity to cool the kth fuel cell in the second time zone Z2 based on input information A from the output control device 20.

[0157] The timing chart for illustrating one control method for the fuel cell power generation system according to the fifth embodiment will not be described here since the above description of FIG. 7 is incorporated herein.

[0158] <<Variations>> Modifications that can be applied to each embodiment will be described.

[0159] <Variation 1> FIG. 9 is a diagram showing a modified example of the cooling system used in the fuel cell power generation system according to this embodiment. The temperature of the heat medium RF2 may fluctuate due to the output fluctuation operation D of the kth fuel cell. In order to suppress this fluctuation, the cooling system 100A may perform temperature control to maintain the temperature of the heat medium RF2 output from the kth fuel cell at or above a predetermined temperature. By performing temperature control to maintain the temperature of the heat medium RF2 at or above a predetermined temperature, the temperature of the heat medium RF2 is stabilized at a high temperature. This makes it easy to reuse the heat of the heat medium RF2 stabilized at a high temperature for other purposes. The predetermined temperature is set to, for example, 60°C.

[0160] For example, when the temperature of the heat medium RF2 detected by the temperature detector 55 drops to a predetermined temperature, the cooling control device 32 reduces the rotation speed of the pump 30. When the rotation speed of the pump 30 decreases, the flow rate of the heat medium RF1 supplied to the k-th fuel cell decreases. Due to the decrease in the flow rate of the heat medium RF1, the ability to cool the k-th fuel cell decreases, so the temperature of the heat medium RF2 is maintained at a high temperature equal to or higher than a predetermined temperature.

[0161] <Variation 2> 10 is a diagram showing a modified example of the cooling system used in the fuel cell power generation system according to this embodiment. The cooling system 100B may perform temperature control to maintain the temperature of the heat medium RF2 output from the k-th fuel cell at a predetermined temperature or higher. This makes it easy to reuse the heat of the heat medium RF2, which is stable in a high-temperature state, for other purposes, as in the cooling system 100A. The predetermined temperature is set to, for example, 60°C.

[0162] For example, when the temperature of the heat medium RF2 detected by the temperature detector 52 drops to a predetermined temperature, the cooling control device 32 reduces the rotation speed of the fan 33a. When the rotation speed of the fan 33a decreases, the temperature of the heat medium RF1 supplied to the k-th fuel cell increases. As the temperature of the heat medium RF1 increases, the ability to cool the k-th fuel cell decreases, so the temperature of the heat medium RF2 is maintained at a high temperature equal to or higher than a predetermined temperature.

[0163] <Variation 3> Fig. 11 is a diagram showing a modified example of a fuel cell used in the fuel cell power generation system according to this embodiment. The cooling system 100C uses a heat exchanger to cool the fuel cell. Fig. 11 illustrates the configuration of the fuel cell 10a, but the other fuel cells 10b, 10c, and 10d may have a similar configuration.

[0164] The fuel cell 10a includes a cell stack 11 in which a plurality of unit cells are stacked, and a heat exchanger 12. The heat exchanger 12 exchanges heat between a heat medium RF and an internal heat medium RFn. The internal heat medium RFn is a heat medium for cooling the cell stack 11 inside the fuel cell 10a.

[0165] <Modification 4> Fig. 12 is a diagram showing a modified example of the fuel cell used in the fuel cell power generation system according to the present embodiment. The cooling system 100D uses a heat exchanger to cool the fuel cell. Fig. 12 illustrates the configuration of the fuel cell 10a, but the other fuel cells 10b, 10c, and 10d may have a similar configuration.

[0166] The cooling system 100D may perform temperature control to maintain the temperature of the internal heat medium RFn at a predetermined temperature or higher after removing heat from the cell stack 11. This makes it easy to reuse the heat of the internal heat medium RFn, which is stable in a high temperature state, for other purposes, as in the cooling system 100A. The predetermined temperature is set to, for example, 60°C.

[0167] For example, when the temperature of the internal heat medium RFn detected by the temperature detector 53 drops to a predetermined temperature, the cooling control device 32 reduces the opening of the adjustment valve 38. When the opening of the adjustment valve 38 decreases, the flow rate of the heat medium RF supplied to the heat exchanger 12 decreases. The reduction in the flow rate of the heat medium RF reduces the ability to cool the cell stack 11, so that the temperature of the internal heat medium RFn is maintained at a high temperature equal to or higher than a predetermined temperature.

[0168] <Variation 5> Fig. 13 is a diagram showing a modified example of a fuel cell used in the fuel cell power generation system according to this embodiment. The cooling system 100E uses a heat exchanger to cool the fuel cell cells and the auxiliary equipment. Fig. 13 illustrates the configuration of the fuel cell 10a, but the other fuel cells 10b, 10c, and 10d may have a similar configuration. The cooling system 100E cools the auxiliary equipment 14, which is an example of a device separate from the cell stack 11.

[0169] In the fifth modification, the fuel cell 10a includes a heat exchanger 13 for cooling the auxiliary equipment 14. The heat exchanger 13 exchanges heat between a heat medium RF and an internal heat medium RFm. The internal heat medium RFm is a heat medium for cooling the auxiliary equipment 14 inside the fuel cell 10a. The auxiliary equipment 14 assists the power generation operation of the cell stack 11. The auxiliary equipment 14 includes, for example, a boost converter that boosts the output power of the cell stack 11, or a compressor motor that supplies compressed air to the cell stack 11.

[0170] In the cooling system 100E, the cooling control device 32 increases the capacity to cool the cell stack 11 and the accessories 14 in the first time zone Z1 more than the capacity to cool the cell stack 11 and the accessories 14 in the second time zone Z2. This achieves variable capacity control. Specifically, the cooling control device 32 achieves variable capacity control by making the opening degree of the regulator valve 38 in the first time zone Z1 larger than the opening degree of the regulator valve 38 in the second time zone Z2.

[0171] The cooling system 100E may perform temperature control to maintain the temperature of the internal heat medium RFn after removing heat from the cell stack 11 at a predetermined temperature or higher, and temperature control to maintain the temperature of the internal heat medium RFm after removing heat from the auxiliary equipment 14 at a predetermined temperature or higher. This makes it easy to reuse the heat of the internal heat mediums RFn, RFm that are stable in a high temperature state for other purposes, just like the cooling system 100A. The predetermined temperature is set to, for example, 60°C.

[0172] For example, when the temperature of the internal heat medium RFn detected by the temperature detector 53 or the temperature of the internal heat medium RFm detected by the temperature detector 54 drops to a predetermined temperature, the cooling control device 32 reduces the opening of the adjustment valve 38. When the opening of the adjustment valve 38 decreases, the flow rate of the heat medium RF supplied to the heat exchangers 12, 13 decreases. The reduction in the flow rate of the heat medium RF reduces the ability to cool the cell stack 11 and the auxiliary machinery 14, so that the temperatures of the internal heat mediums RFn, RFm are maintained at a high temperature equal to or higher than a predetermined temperature.

[0173] <Variation 6> Fig. 14 is a diagram showing a modified example of a fuel cell used in the fuel cell power generation system according to this embodiment. The cooling system 100F uses a heat exchanger to cool the fuel cell cells and the auxiliary equipment. Fig. 14 illustrates the configuration of the fuel cell 10a, but the other fuel cells 10b, 10c, and 10d may have a similar configuration. The cooling system 100F cools the auxiliary equipment 14, which is an example of a device separate from the cell stack 11.

[0174] In the cooling system 100F, the cooling control device 32 increases the capacity to cool the cell stack 11 in the first time zone Z1 more than the capacity to cool the cell stack 11 in the second time zone Z2. This performs capacity variable control to increase the capacity to cool the cell stack 11. Specifically, the cooling control device 32 performs capacity variable control to increase the capacity to cool the cell stack 11 by making the opening degree of the adjustment valve 38 in the first time zone Z1 larger than the opening degree of the adjustment valve 38 in the second time zone Z2.

[0175] On the other hand, the cooling control device 32 does not increase the capacity to cool the auxiliary device 14 in the first time zone Z1 more than the capacity to cool the auxiliary device 14 in the second time zone Z2. This prevents the capacity variable control from being performed to increase the capacity to cool the auxiliary device 14. By not performing the capacity variable control to increase the capacity to cool the auxiliary device 14, the power consumption of the cooling system 100D can be reduced.

[0176] The flow rate of the heat medium RF flowing through the heat exchanger 13 may be adjusted by a manual valve 41.

[0177] As described above, the embodiment has been described, but the above embodiment is presented as an example, and the present invention is not limited to the above embodiment. The above embodiment can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0178] For example, the capacity variable control according to the third embodiment may be combined with the capacity variable control according to the first or second embodiment.

[0179] In the above embodiment, the cooling system adjusts the capacity to cool the k-th fuel cell by the heat medium RF. However, the cooling system may adjust the capacity to cool the k-th fuel cell by a means other than the heat medium RF. [Explanation of symbols]

[0180] 1,2,3,4,5 Fuel Cell Power Generation System 10a,10b,10c,10d Fuel cell 11 Cell stack 12,13 Heat exchanger 14 Auxiliary Equipment 30, 30a, 30b, 30c, 30d Pump 31, 31a, 31b, 31c, 31d Inverter 32 Cooling control device 33 Cooling device 33a Fan 34 Flow Path 35 Main channel 35a,35b,35c,35d Branch channel 36 Flow Path 37 Main channel 37a,37b,37c,37d Branch channel 38, 38a, 38b, 38c, 38d Control valve 39 Inverter 40 Storage Battery 41 Manual valve 50 Power conversion device 51 Output line 52, 53, 54, 55 Temperature detector 100A, 100B, 100C, 100D, 100E, 100F Cooling system 101,102,103,104,105 Cooling system 200 packages RF,RF1,RF2 Heat medium RFm,RFn Internal heating medium

Claims

1. N fuel cells, N being an integer equal to or greater than 2; an output control device that causes the N fuel cells to perform an output fluctuation operation in which the output power is varied; a cooling system that, for the N fuel cells, increases the ability to cool the kth fuel cell during a first time period when the kth fuel cell performs the output fluctuation operation, compared to the ability to cool the kth fuel cell during a second time period when the kth fuel cell does not perform the output fluctuation operation, where k is an integer greater than 1 and less than N.

2. 2. The fuel cell power generation system according to claim 1, wherein the cooling system increases its ability to cool the kth fuel cell prior to the first time period.

3. 2. The fuel cell power generation system of claim 1, wherein the cooling system increases its ability to cool the kth fuel cell until after the first time period.

4. 2. The fuel cell power generation system according to claim 1, wherein the second time period is a time period during which none of the N fuel cells performs the output fluctuation operation.

5. 2. The fuel cell power generation system according to claim 1, wherein said cooling system collectively increases the capacity to cool each of said N fuel cells.

6. 2. The fuel cell power generation system of claim 1, wherein the cooling system increases the capacity to cool each of the N fuel cells during a time period when any one or more of the N fuel cells is performing the output fluctuation operation, more than the capacity during a time period when none of the N fuel cells is performing the output fluctuation operation.

7. 2. The fuel cell power generation system of claim 1, wherein said cooling system individually increases the cooling capacity of each of said N fuel cells.

8. 2. The fuel cell power generation system of claim 1, wherein the cooling system increases the capacity to cool the kth fuel cell during the first time period more than the capacity to cool the kth fuel cell during the second time period based on input information from the output control device.

9. The fuel cell power generation system according to claim 8 , wherein the input information includes operation information related to the output fluctuation operation.

10. 9. The fuel cell power generation system according to claim 8, wherein the input information includes instruction information regarding adjustment of a capacity for cooling each of the N fuel cells.

11. 2. The fuel cell power generation system according to claim 1, wherein the cooling system adjusts the capacity of cooling the kth fuel cell by a heat medium.

12. 12. The fuel cell power generation system according to claim 11, wherein the cooling system increases the flow rate of the heat transfer medium supplied to the kth fuel cell during the first time period to be greater than the flow rate of the heat transfer medium supplied to the kth fuel cell during the second time period.

13. 13. The fuel cell power generation system of claim 12, wherein the cooling system includes a common pump that sends the heat transfer medium to the N fuel cells, and the rotation speed of the pump during the first time period is set higher than the rotation speed of the pump during the second time period.

14. 13. The fuel cell power generation system according to claim 12, wherein the cooling system includes a plurality of pumps provided for each of the N fuel cells, for feeding the heat transfer medium to the corresponding fuel cell, and the rotation speed of each of the plurality of pumps is increased individually.

15. 13. The fuel cell power generation system of claim 12, wherein the cooling system includes a common adjustment valve that adjusts the flow rate of the heat transfer medium supplied to the N fuel cells, and the opening degree of the adjustment valve during the first time period is greater than the opening degree of the adjustment valve during the second time period.

16. 13. The fuel cell power generation system of claim 12, wherein the cooling system includes a plurality of regulating valves provided for each of the N fuel cells, regulating the flow rate of the heat transfer medium supplied to the corresponding fuel cell, and increasing the opening degree of each of the plurality of regulating valves individually.

17. 12. The fuel cell power generation system according to claim 11, wherein the cooling system lowers the temperature of the heat medium supplied to the kth fuel cell during the first time period below the temperature of the heat medium supplied to the kth fuel cell during the second time period.

18. 18. The fuel cell power generation system according to claim 17, wherein the cooling system includes a fan that supplies air to cool the heat transfer medium, and the rotation speed of the fan in the first time period is set higher than the rotation speed of the fan in the second time period.

19. the kth fuel cell includes a cell stack and an auxiliary device that assists the power generation operation of the cell stack, 2 . The fuel cell power generation system according to claim 1 , wherein the cooling system increases a capacity for cooling the cell stack during the first time period more than a capacity for cooling the cell stack during the second time period.

20. 20. The fuel cell power generation system of claim 19, wherein the cooling system does not increase its ability to cool the accessories during the first time period more than its ability to cool the accessories during the second time period.

21. 2. The fuel cell power generation system according to claim 1, wherein the cooling system cools the kth fuel cell using a heat transfer medium circulating between the kth fuel cell and the kth fuel cell, and maintains the temperature of the heat transfer medium output from the kth fuel cell at or above a predetermined temperature.

22. 22. The fuel cell power generation system according to claim 1, wherein the output fluctuation operation includes a refresh operation of the kth fuel cell.

23. the first time period during which the k fuel cell performs the refresh operation includes a low load period during which the output power of the k fuel cell is either 0% or more and 20% or less of a maximum output of the k fuel cell, 23. The fuel cell power generation system of claim 22, wherein the cooling system increases its ability to cool the kth fuel cell during the low load period more than its ability to cool the kth fuel cell during the second time period.

24. the first time period during which the k fuel cell performs the refresh operation includes a low load period during which the output power of the k fuel cell is any one of 0% or more and 20% or less of a maximum output of the k fuel cell, and a high load period during which the output power of the k fuel cell is any one of 80% or more and 100% or less of a maximum output of the k fuel cell, 23. The fuel cell power generation system of claim 22, wherein the cooling system is configured to reduce its ability to cool the kth fuel cell during the low load periods relative to its ability to cool the kth fuel cell during the high load periods.

25. A method for controlling power generation and cooling of N fuel cells, N being an integer equal to or greater than 2, comprising the steps of: causing the N fuel cells to perform a variable output operation in which the output power is varied; A control method, where k is an integer greater than or equal to 1 and less than or equal to N, for the N fuel cells, increasing the capacity of cooling the kth fuel cell during a first time period when the kth fuel cell performs the output fluctuation operation more than the capacity of cooling the kth fuel cell during a second time period when the kth fuel cell does not perform the output fluctuation operation.

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