Control method for fuel cell power generation system, control program for fuel cell power generation system, and fuel cell power generation system

Abstract

A technology is provided that can improve the efficiency of maintenance work in a fuel cell power generation system and can reliably meet the power demand of a load. A fuel cell power generation system includes a plurality of fuel cell power generation devices each having a fuel cell. A control method for the fuel cell power generation system includes determining an operating mode for each fuel cell power generation device based on the power demand of a load electrically connected to each fuel cell power generation device and the state of each fuel cell power generation device.

Description

[Technical Field]

[0001] The present invention relates to a control method for a fuel cell power generation system, a control program for a fuel cell power generation system, and a fuel cell power generation system. [Background technology]

[0002] A cogeneration system equipped with a gas engine is known as a conventional technology (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6321484 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, from the viewpoint of carbon neutrality, fuel cell power generation devices (e.g., fuel cell cogeneration devices) that have fuel cells are desired. If a fuel cell power generation system is configured by providing multiple fuel cell power generation devices, it becomes possible to output (generate) greater power. However, for example, if the operation of each fuel cell power generation device is carried out regardless of the power demand of the load to which the generated power of each fuel cell power generation device is supplied, there is a risk that the total generated power of each fuel cell power generation device will be insufficient to meet the power demand of the load, and the power demand of the load will not be met.

[0005] Furthermore, as each fuel cell power generation device operates, the deterioration of each part (e.g., fuel cell) progresses. Therefore, maintenance work is required depending on the condition (e.g., operating time) of each fuel cell power generation device. However, if the condition of each fuel cell power generation device varies greatly, the timing of maintenance work will be spread out, which may reduce the efficiency of the maintenance work.

[0006] The present invention has been made to solve the above problems, and its purpose is to provide a technology that can improve the efficiency of maintenance work in a fuel cell power generation system and can reliably meet the power demand of the load. [Means for solving the problem]

[0007] A control method for a fuel cell power generation system according to one aspect of the present invention is a control method for a fuel cell power generation system having a plurality of fuel cell power generation devices each having a fuel cell, and includes determining the operating mode of each fuel cell power generation device based on the power demand of a load electrically connected to each fuel cell power generation device and the state of each fuel cell power generation device.

[0008] A control program for a fuel cell power generation system according to another aspect of the present invention causes at least one arithmetic device to execute the above control method.

[0009] A fuel cell power generation system according to another aspect of the present invention is a fuel cell power generation system having a plurality of fuel cell power generation devices each having a fuel cell, and further comprising an operation control unit that determines the operating mode of each fuel cell power generation device based on the power demand of a load electrically connected to each fuel cell power generation device and the state of each fuel cell power generation device. [Effects of the Invention]

[0010] According to the above configuration, it is possible to improve the efficiency of maintenance work on the fuel cell power generation system, and also to reliably cover the power demand of the load. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a schematic configuration of a fuel cell power generation system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a block diagram showing a schematic configuration of a plurality of fuel cell cogeneration devices included in the fuel cell power generation system. [Figure 3]5 is a flowchart showing a flow when a target generated power is calculated for each of the fuel cell cogeneration systems. [Figure 4] FIG. 4 is an explanatory diagram illustrating a method for selecting an operation target in the fuel cell power generation system. [Figure 5] 10 is a flowchart showing a flow when the number of operating fuel cell cogeneration systems is changed when a fuel cell included in the fuel cell cogeneration system is not generating electricity properly. [Figure 6] FIG. 10 is an explanatory diagram illustrating a modified example of the method for selecting the driving target. [Figure 7] FIG. 10 is an explanatory diagram illustrating another modified example of the method for selecting the operating object. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes an embodiment of the present invention with reference to the drawings.

[0013] [1. Outline of fuel cell power generation system] 1 is a block diagram showing a schematic configuration of a fuel cell power generation system 1 according to one embodiment of the present invention. The fuel cell power generation system 1 includes a plurality of (three in this embodiment) fuel cell cogeneration systems 2 and a system controller 3. The fuel cell cogeneration systems 2 are an example of fuel cell power generation systems FCG. That is, the fuel cell power generation systems FCG include the fuel cell cogeneration systems 2. Each fuel cell cogeneration system 2 is interconnected with a commercial power grid 101.

[0014] The number of fuel cell cogeneration units 2 (also referred to as the number of installed units) in the fuel cell power generation system 1 is not limited to three, and may be, for example, two, four or more. In this embodiment, one of the three fuel cell cogeneration units 2 is referred to as the first fuel cell cogeneration unit 2A. One of the remaining two units is referred to as the second fuel cell cogeneration unit 2B, and the other is referred to as the third fuel cell cogeneration unit 2C.

[0015] Each fuel cell cogeneration system 2 generates power using fuel gas and oxidant gas supplied from outside the fuel cell cogeneration system 2. In this embodiment, an example will be described in which hydrogen gas is used as the fuel gas and air is used as the oxidant gas. However, the fuel gas is not limited to hydrogen gas and may be, for example, a gas containing methane as a main component. Furthermore, the oxidant gas is not limited to air and may be any gas containing oxygen. The configuration (internal configuration) of the fuel cell cogeneration system 2 will be described later.

[0016] The commercial power system 101 includes a commercial power source 101a and supplies commercial power generated by the commercial power source 101a. A load 102 is connected to the commercial power system 101. That is, the load 102 is electrically connected to each fuel cell power generator FCG (fuel cell cogeneration systems 2 in this embodiment). The load 102 includes, for example, household electrical appliances, industrial (industrial, facility) electrical appliances, etc. Specifically, motors, pumps, etc. provided in such appliances consume power. The power demand (power consumption) of the load 102 is met by the power generated by each fuel cell cogeneration system 2 and the commercial power supplied from the commercial power system 101. Note that the configuration related to the power supply to the load 102 is not limited to the above. For example, the load 102 may be configured to be directly connected to each fuel cell cogeneration system 2 without being connected to the commercial power system 101. In this case, the power demand of the load 102 is met by the power generated by each fuel cell cogeneration system 2. The power demand of the load 102 is detected by a power detector 103 provided on the commercial power system 101 .

[0017] The system controller 3 controls the fuel cell power generation system 1. The system controller 3 is, for example, a computer device including an arithmetic device 31, a storage unit 32, and an input / output unit (not shown). The arithmetic device 31 is, for example, a processor or a microprocessor. In FIG. 1, as an example, one arithmetic device 31 is shown in the system controller 3, but the number of arithmetic devices 31 may be two, three, or more.

[0018] The storage unit 32 is a main storage device such as a read-only memory (ROM) or a random access memory (RAM). The storage unit 32 may further include an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). The storage unit 32 stores various programs, data, and the like. The various programs include a control program 32a relating to the operation method of each fuel cell cogeneration system 2. For example, the arithmetic unit 31 reads the control program 32a from the storage unit 32 and executes arithmetic processing in accordance with the control program 32a. The programs stored in the storage unit 32 may be provided, for example, by a computer-readable nonvolatile recording medium. As another example, the programs may be provided from a program providing server via a communication line such as the Internet.

[0019] The above-mentioned hardware and software work together to allow the system controller 3 to operate as an operation control unit 3a. That is, the fuel cell power generation system 1 includes an operation control unit 3a. The system controller 3 may be configured as a single piece of hardware, or may be configured as multiple pieces of hardware that can communicate with each other.

[0020] The operation control unit 3a included in the system controller 3 may be realized by causing the arithmetic device 31 to execute arithmetic processing according to a program, i.e., by software, as described above, but may also be realized by other methods. The operation control unit 3a may be realized, for example, by using an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). That is, the operation control unit 3a may be realized by hardware using a dedicated IC or the like. The operation control unit 3a may also be realized by a combination of software and hardware. The operation control unit 3a is a conceptual configuration. Therefore, the functions performed by the operation control unit 3a may be distributed among multiple components, or the functions of multiple components may be integrated into the operation control unit 3a.

[0021] The operation control unit 3a controls the operation of each fuel cell cogeneration unit 2 based on the power demand of the load 102, the state of each fuel cell cogeneration unit 2, such as the operation time 2T (see FIG. 4 ), which will be described later, and other factors. Therefore, the control method of the fuel cell power generation system 1, which is related to the operation method of each fuel cell cogeneration unit 2, executed by the operation control unit 3a, is realized by having the arithmetic unit 31 execute arithmetic processing in accordance with the control program 32a, similar to the operation control unit 3a. In this embodiment, as described above, one arithmetic unit 31 executes the above arithmetic processing. However, if there are two or more arithmetic units 31, the arithmetic processing may be executed by two or more arithmetic units 31. In other words, the control program 32a of the fuel cell power generation system 1 of this embodiment is a program that causes at least one arithmetic unit 31 to execute the control method of the fuel cell power generation system 1. The operation method of each fuel cell cogeneration unit 2 by the operation control unit 3a will be described later.

[0022] [2. Configuration of fuel cell cogeneration system] The configuration of the fuel cell cogeneration system 2 will be described with reference to Fig. 2. Fig. 2 is a block diagram that schematically shows the general configuration of the fuel cell cogeneration system 2.

[0023] In this embodiment, the first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C are the same (have the same configuration). However, the fuel cell power generation system 1 is not limited to a configuration in which the multiple fuel cell cogeneration units 2 are the same, and for example, the multiple fuel cell cogeneration units 2 may have different configurations. Specifically, in the fuel cell power generation system 1, the multiple fuel cell cogeneration units 2 may have different configurations, specifications (e.g., rated output), etc.

[0024] Each fuel cell cogeneration system 2 includes a fuel cell module 21, a battery 22, an inverter 23, and a system controller 24. The components of the fuel cell cogeneration system 2 (for example, the fuel cell FC of the fuel cell module 21, which will be described later) deteriorate as the fuel cell cogeneration system 2 continues to operate.

[0025] In this embodiment, each fuel cell cogeneration system 2 is provided with one fuel cell module 21, one inverter 23, and one device controller 24, and multiple batteries 22. However, FIG. 2 shows only one battery 22 as an example. The numbers of fuel cell modules 21, batteries 22, inverters 23, and device controllers 24 are not limited to those described above. For example, there may be multiple fuel cell modules 21, multiple inverters 23, and multiple device controllers 24, or there may be only one battery 22. The fuel cell module 21, battery 22, inverter 23, and device controller 24 are disposed inside each fuel cell cogeneration system 2.

[0026] The fuel cell module 21 has a fuel cell FC, a boost converter 21b, a compressor 21c, and a fuel cell control unit 21d. That is, the fuel cell power generation system FCG (fuel cell cogeneration system 2 in this embodiment) has the fuel cell FC, the boost converter 21b, the compressor 21c, and the fuel cell control unit 21d.

[0027] A fuel cell FC (also called a fuel cell stack) is composed of multiple stacked cells. Each cell includes a solid polymer electrolyte membrane, an anode, a cathode, and a pair of separators. The anode and cathode sandwich the solid polymer electrolyte membrane. The anode is the negative electrode (fuel electrode) and includes an anode catalyst layer and a gas diffusion layer. The cathode is the positive electrode (air electrode) and includes a cathode catalyst layer and a diffusion layer. The anode, solid polymer electrolyte membrane, and cathode form a membrane electrode assembly (MEA). The pair of separators sandwich the membrane electrode assembly. Each separator has multiple grooves. The grooves of one separator form a flow path for hydrogen gas. The grooves of the other separator form a flow path for air.

[0028] At the anode side, hydrogen is decomposed into hydrogen ions and electrons by a catalyst. The hydrogen ions pass through the solid polymer electrolyte membrane and move to the cathode side. Meanwhile, the electrons pass through an external circuit and move to the cathode side. This generates an electric current (electricity is generated). At the cathode side, oxygen contained in the air combines with the electrons that have flowed through the external circuit and the hydrogen ions that have passed through the solid polymer electrolyte membrane to produce water. The produced water is contained in the exhaust gas and discharged outside the fuel cell cogeneration system 2.

[0029] The electric power generated by the fuel cell FC is boosted by the boost converter 21b and supplied to the inverter 23. Note that the electric power generated by the fuel cell FC and boosted by the boost converter 21b may also be supplied to the battery 22 in addition to the inverter 23.

[0030] The fuel cell FC generates heat when generating electricity. More specifically, the amount of heat generated by the fuel cell FC increases as the amount of power generated increases. The heat (waste heat) generated by the power generation of the fuel cell FC is recovered inside the fuel cell cogeneration system 2 and is effectively utilized, for example, for hot water supply, heating, etc. In other words, the fuel cell cogeneration system 2 recovers the waste heat generated by the power generation of the fuel cell FC.

[0031] From the viewpoint of improving overall efficiency by utilizing the waste heat generated by the fuel cell FC, it is desirable that the fuel cell power generation system FCG, as in this embodiment, includes a fuel cell cogeneration system 2 that recovers the waste heat generated by the fuel cell FC.

[0032] However, the waste heat recovery function is not essential for the fuel cell power generation system FCG. That is, the fuel cell power generation system FCG may include a simple power generation system (e.g., a monogeneration system) that has a fuel cell FC but does not have the waste heat recovery function. The above-mentioned power generation system is another example of the fuel cell power generation system FCG.

[0033] In this embodiment, the fuel cell FC of the first fuel cell cogeneration system 2A is also called the first fuel cell FC1 (see FIG. 1). The fuel cell FC of the second fuel cell cogeneration system 2B is also called the second fuel cell FC2 (see FIG. 1). The fuel cell FC of the third fuel cell cogeneration system 2C is also called the third fuel cell FC3 (see FIG. 1).

[0034] The compressor 21c is provided to take in air to be supplied to the fuel cell FC from outside the fuel cell cogeneration system 2. The air taken in from outside the fuel cell cogeneration system 2 by the compressor 21c flows into the fuel cell FC via multiple filters (none of which are shown) provided inside the fuel cell cogeneration system 2.

[0035] The fuel cell control unit 21d controls each part of the fuel cell module 21. The fuel cell control unit 21d controls, for example, the power generation of the fuel cell FC, the driving of the compressor 21c, etc. The fuel cell control unit 21d is communicably connected to the device controller 24. Communication between the fuel cell control unit 21d and the device controller 24 is performed by, for example, CAN communication, but the communication method is not limited to CAN communication.

[0036] The battery 22 is formed of, for example, a lithium ion battery, and stores the power supplied to the inverter 23. The battery 22 may be formed by unitizing a plurality of battery cells, or may be formed by a single battery cell. As described above, the battery 22 may be supplied with power generated by the fuel cell FC. The battery 22 is charged by the power supplied from the fuel cell FC to the battery 22.

[0037] The battery 22 is controlled by a battery control unit 22a. The battery control unit 22a is also called a BMU (Battery Management Unit), and controls, for example, the input and output of the battery 22. The battery control unit 22a also calculates the state of charge (SOC) of the battery 22 based on information (for example, the voltage, current, temperature, etc. of the battery 22) acquired via various sensors (not shown) provided in the battery 22. The state of charge of the battery 22 means the ratio of the remaining charge capacity (at that time) to the charge capacity when fully charged.

[0038] The battery control unit 22a is communicatively connected to the equipment controller 24. Communication between the battery control unit 22a and the equipment controller 24 is performed, for example, by CAN communication, but the communication method is not limited to CAN communication. The battery control unit 22a transmits, for example, information about the battery 22 (including the charging rate calculated by the battery control unit 22a) to the equipment controller 24 via CAN communication.

[0039] The inverter 23 is configured by mounting various electrical components (e.g., diodes, capacitors, power transistors, etc.) on a substrate (none of which are shown). The inverter 23 converts DC voltage power supplied from at least one of the fuel cell FC and the battery 22 into AC voltage power and supplies it to the load 102 (see FIG. 1). More specifically, the inverter 23 supplies AC power to the load 102 in accordance with the power demand of the load 102. For example, when the power demand of the load 102 increases, the inverter 23 increases the AC power supplied to the load 102, and when the power demand of the load 102 decreases, the inverter 23 reduces the AC power supplied to the load 102.

[0040] The inverter 23 is communicably connected to the equipment controller 24. Communication between the inverter 23 and the equipment controller 24 is performed, for example, by CAN communication, but the communication method is not limited to CAN communication. The inverter 23 transmits information about the power output from the inverter 23 (at that time) to the equipment controller 24 via CAN communication.

[0041] The equipment controller 24 controls each part of the fuel cell cogeneration system 2. For example, the equipment controller 24 outputs a power generation instruction for the fuel cell FC to the fuel cell control unit 21d based on an operation instruction output from the system controller 3 (see FIG. 1). Based on this power generation instruction, the fuel cell control unit 21d controls the power generation of the fuel cell FC.

[0042] The fuel cell cogeneration system 2 has a first operation mode and a second operation mode. In the first operation mode, (all) the electric power generated by the fuel cell FC is supplied to the load 102 via the boost converter 21b and the inverter 23.

[0043] The second operating mode includes a charge mode and a discharge mode. In the charge mode, a portion of the power generated by the fuel cell FC is supplied to the load 102, and the remainder of the power generated by the fuel cell FC is supplied to the battery 22. In the discharge mode, power generation by the fuel cell FC is stopped, and power discharged from the battery 22 is supplied to the load 102. Hereinafter, unless otherwise specified, it is assumed that the fuel cell cogeneration system 2 is operated in the first operating mode. However, this assumption is used merely for the purpose of explanation and is not intended to limit the actual operating mode.

[0044] 3. Method of operating fuel cell cogeneration system [3-1. Method for calculating target power generation for fuel cell cogeneration equipment] FIG. 3 is a flowchart showing the flow when the target generated power TP of each fuel cell cogeneration plant 2 is calculated.

[0045] In step S1, the operation control unit 3a of the system controller 3 (see FIG. 1) acquires the power demand of the load 102 (see FIG. 1). As described above, the power demand of the load 102 is detected by the power detector 103 (see FIG. 1). Once the power demand of the load 102 is acquired, the process proceeds to the next step S2.

[0046] In step S2, the operation control unit 3a calculates the number 2N of operating fuel cell cogeneration plants 2 based on the power demand of the load 102 (acquired in step S1) and the rated output of the fuel cell cogeneration plant 2. That is, the control method for the fuel cell power generation system 1 of this embodiment includes calculating the number 2N of operating fuel cell power generation plants FCG (fuel cell cogeneration plants 2 in this embodiment) based on the power demand of the load 102. In this embodiment, the number 2N of operating plants is calculated by dividing the power demand of the load 102 by the rated output of the fuel cell cogeneration plant 2 and rounding up to the nearest integer. Once the number 2N of operating plants is calculated, processing proceeds to the next step S3.

[0047] In step S3, the operation control unit 3a calculates the target power generation power TP of the fuel cell cogeneration system 2 based on the power demand of the load 102 (acquired in step S1) and the number 2N of operating units (calculated in step S2). In this embodiment, the target power generation power TP is calculated by dividing the power demand of the load 102 by the number 2N of operating units.

[0048] If the power demand of the load 102 is greater than the rated output of the fuel cell power generation system 1, the operation control unit 3a sets the rated output of each fuel cell cogeneration device 2 as the target power generation power TP of each fuel cell cogeneration device 2. The rated output of the fuel cell power generation system 1 means the sum of the rated outputs of the multiple fuel cell cogeneration devices 2 included in the fuel cell power generation system 1.

[0049] The calculated target power generation TP is output to one of the multiple (three in this embodiment) fuel cell cogeneration systems 2 that is to be operated. Each of the fuel cell cogeneration systems 2 that is to be operated is operated based on this target power generation TP. Therefore, the fuel cell cogeneration systems 2 that are in operation generate (output) the same amount of power (target power generation TP). In other words, the control method for the fuel cell power generation system 1 of this embodiment includes equalizing the target power generation TP of the fuel cell power generation systems FCG (fuel cell cogeneration systems 2 in this embodiment) based on the number 2N of operating fuel cell power generation systems FCG. A method for selecting the system to be operated will now be described.

[0050] [3-2. How to select the operation target] Figure 4 is an explanatory diagram illustrating a method for selecting an operating target. Figure 4 illustrates an example of changes in the operating time 2T of the fuel cell cogeneration system 2. In detail, the operating time 2AT of the first fuel cell cogeneration system 2A is shown by a solid line, the operating time 2BT of the second fuel cell cogeneration system 2B is shown by a dashed line, and the operating time 2CT of the third fuel cell cogeneration system 2C is shown by a dotted and dashed line. Also in Figure 4, the number 2N of operating fuel cell cogeneration systems 2 is shown by a two-dot chain line.

[0051] In this embodiment, the operating time 2T of each fuel cell cogeneration system 2 means the cumulative operating time since maintenance work was performed on each fuel cell cogeneration system 2. Therefore, the operating time 2T of each fuel cell cogeneration system 2 is reset (returned to zero) every time maintenance work is performed.

[0052] The operating time 2T of the fuel cell cogeneration system 2 is an example of the state of the fuel cell cogeneration system 2. That is, the state of each fuel cell power generator FCG (fuel cell cogeneration system 2 in this embodiment) includes the operating time 2T of each fuel cell power generator FCG.

[0053] At time t0, of the operating times 2T of the fuel cell cogeneration plants 2, the operating time 2AT of the first fuel cell cogeneration plant 2A is the shortest, and the operating time 2CT of the third fuel cell cogeneration plant 2C is the longest.

[0054] During the period from time t0 to time t1, the number of operating units 2N is the first number of operating units 2N1 (0 in this embodiment). As described above, the number of operating units 2N is calculated by dividing the power demand of the load 102 by the rated output of the fuel cell cogeneration system 2 and rounding up to the nearest integer (see step S2 in FIG. 3), and therefore, in this case, the power demand of the load 102 is zero.

[0055] At time t1, the power demand of the load 102 increases (slightly) from zero. As a result, the number of operating units 2N calculated by the operation control unit 3a (see FIG. 1) becomes the second number of operating units 2N2 (one unit in this embodiment). Here, the operation control unit 3a selects the fuel cell cogeneration units 2 equivalent to the second number of operating units 2N2 as the operation targets. In this embodiment, the operation control unit 3a selects, from among the fuel cell cogeneration units 2, the first fuel cell cogeneration unit 2A that has the shortest operating time 2T at time t1 as the operation target.

[0056] A target power generation output TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A selected for operation. The target power generation output TP at this time is calculated by dividing the power demand of the load 102 by the second number of operating units 2N2 (1 in this embodiment). The first fuel cell cogeneration unit 2A is operated based on this target power generation output TP. As a result, the operating time 2AT of the first fuel cell cogeneration unit 2A gradually increases (see, for example, the period from time t1 to time t2). In other words, the control method for the fuel cell power generation system 1 of this embodiment includes giving priority to the operation of a fuel cell power generation unit FCG with a short operating time 2T among multiple fuel cell power generation units FCG (fuel cell cogeneration units 2 in this embodiment).

[0057] At time t2, the power demand of the load 102 increases from the power demand of the load 102 at time t1, for example. As a result, the number of operating units 2N becomes the third number of operating units 2N3 (two in this embodiment). Here, the operation control unit 3a selects the fuel cell cogeneration units 2 equivalent to the third number of operating units 2N3 as the operation targets. In this embodiment, the operation control unit 3a selects the fuel cell cogeneration units 2 in order starting with the fuel cell cogeneration unit 2 with the shortest operating time 2T at time t2. That is, the operation control unit 3a selects the first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B as the operation targets. In other words, of the multiple fuel cell cogeneration units 2, the fuel cell cogeneration unit 2 with the shortest operating time 2T is preferentially selected as the operation target.

[0058] A target power generation output TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B selected for operation. The target power generation output TP at this time is calculated by dividing the power demand of the load 102 by the third number of operating units 2N3 (two in this embodiment). The first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B are each operated based on this target power generation output TP. As a result, the operating time 2AT of the first fuel cell cogeneration unit 2A and the operating time 2BT of the second fuel cell cogeneration unit 2B each gradually increase (see, for example, the period from time t2 to time t3).

[0059] At time t3, the difference between the operation time 2AT of the first fuel cell cogeneration plant 2A and the operation time 2CT of the (stopped) third fuel cell cogeneration plant 2C reaches a predetermined threshold (e.g., 100 hours). Here, the operation control unit 3a excludes the first fuel cell cogeneration plant 2A from the plants to be operated and selects the third fuel cell cogeneration plant 2C as the plant to be operated. In other words, the plant to be operated is changed.

[0060] The operation control unit 3a may change the operating target in other cases. For example, the change may be made when the difference between the operating time 2AT of the first fuel cell cogeneration unit 2A and the operating time 2BT of the second fuel cell cogeneration unit 2B reaches the threshold value. Alternatively, the change may be made when the difference between the operating time 2BT of the second fuel cell cogeneration unit 2B and the operating time 2CT of the third fuel cell cogeneration unit 2C reaches the threshold value. In other words, the control method for the fuel cell power generation system 1 of this embodiment includes changing the fuel cell power generation unit FCG to be operated when any of the differences in the operating time 2T of each fuel cell power generation unit FCG reaches a predetermined threshold value. In other words, the change in the fuel cell power generation unit FCG to be operated is made when the difference between the maximum and minimum values ​​of the operating time 2T of each fuel cell cogeneration unit 2 at each time point reaches the threshold value.

[0061] The system controller 3 (operation control unit 3a) outputs a target power generation output TP to the third fuel cell cogeneration unit 2C selected for operation. The target power generation output TP at this time is the same as the target power generation output TP calculated at time t2. The third fuel cell cogeneration unit 2C is operated based on this target power generation output TP. As a result, the operation time 2CT of the third fuel cell cogeneration unit 2C gradually increases (see, for example, the period from time t3 to time t4).

[0062] Meanwhile, operation of the first fuel cell cogeneration unit 2A is stopped. As a result, the operating time 2AT of the first fuel cell cogeneration unit 2A does not increase. Therefore, the operating time 2AT of the first fuel cell cogeneration unit 2A from time t3 onwards (more specifically, the period from time t3 to time t4) remains the same as the operating time 2AT at time t3.

[0063] At time t4, the power demand of the load 102 increases from the power demand of the load 102 at time t2, for example. As a result, the number of operating units 2N becomes the fourth number of operating units 2N4 (three in this embodiment). Here, the operation control unit 3a selects the fourth number of operating units 2N4 of fuel cell cogeneration units 2 as the operation targets. In this embodiment, since the fourth number of operating units 2N4 is the same as the number of installed units, the operation control unit 3a selects the first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C as the operation targets. In other words, all of the multiple fuel cell cogeneration units 2 in the fuel cell power generation system 1 are selected as operation targets.

[0064] A target power generation output TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C selected for operation. The target power generation output TP is calculated by dividing the power demand of the load 102 by the fourth number of operating units 2N4 (three in this embodiment). The first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C are each operated based on this target power generation output TP. As a result, the operating time 2AT of the first fuel cell cogeneration unit 2A gradually increases. Furthermore, the operating time 2BT of the second fuel cell cogeneration unit 2B gradually increases. Furthermore, the operating time 2CT of the third fuel cell cogeneration unit 2C gradually increases (see the period from time t4 onwards for all of these).

[0065] In this way, the operation of each fuel cell cogeneration apparatus 2 is performed so that the variation in the state of each fuel cell cogeneration apparatus 2 (for example, operating time 2T) falls within a certain range. Also, as described above, the fuel cell cogeneration apparatuses 2 in operation generate the same electric power (target power generation power TP calculated based on the power demand of the load 102). In other words, the control method for the fuel cell power generation system 1 of this embodiment includes determining the operation mode of each fuel cell power generation apparatus FCG based on the power demand of the load 102 and the state of each fuel cell power generation apparatus FCG (fuel cell cogeneration apparatus 2 in this embodiment). Also, the operation control unit 3a provided in the fuel cell power generation system 1 determines the operation mode of each fuel cell power generation apparatus FCG based on the power demand of the load 102 and the state of each fuel cell power generation apparatus FCG.

[0066] According to the above configuration, it is possible to suppress an increase in the variation in the state (operating time 2T in this embodiment) of each fuel cell power generator FCG (fuel cell cogeneration system 2 in this embodiment) provided in the fuel cell power generation system 1. As a result, maintenance work required according to the state of each fuel cell power generator FCG can be performed all at once, improving the efficiency of maintenance work in the fuel cell power generation system 1. Furthermore, the power generated by each fuel cell power generator FCG can be increased or decreased uniformly while corresponding to the power demand of the load 102. As a result, the total power generated by each fuel cell power generator FCG will not be insufficient for the power demand of the load 102, and the power demand of the load 102 can be reliably met. As described above, it is possible to improve the efficiency of maintenance work in the fuel cell power generation system 1 and reliably meet the power demand of the load 102.

[0067] If the number 2N of operating fuel cell cogeneration systems 2 is calculated based on the power demand of the load 102, the number 2N of operating systems required to cover the power demand of the load 102 is reliably secured. Furthermore, if the number 2N of operating systems is smaller than the number of installed systems, operation of some of the fuel cell cogeneration systems 2 will be stopped. For example, in a case where three fuel cell cogeneration systems 2 are provided, as in this embodiment, if the number 2N of operating systems is two, operation of one fuel cell cogeneration system 2 will be stopped. Stopping operation of a fuel cell cogeneration system 2 prevents deterioration of each component of the fuel cell cogeneration system 2 (e.g., the fuel cell FC). This reduces the frequency of maintenance work and improves the efficiency of the maintenance work. Therefore, from the perspective of reliably realizing a configuration that improves the efficiency of maintenance work in the fuel cell power generation system 1 and covers the power demand of the load 102 at the same time, the following configuration is desirable. That is, as in this embodiment, it is desirable that the control method for the fuel cell power generation system 1 includes calculating the number 2N of operating fuel cell power generation units FCG (fuel cell cogeneration units 2 in this embodiment) based on the power demand of the load 102.

[0068] The greater the power generation of the fuel cell cogeneration system 2, the more likely the deterioration of each part of the fuel cell cogeneration system 2 progresses. Therefore, for example, if the power generation of each fuel cell cogeneration system 2 differs from one another, the progression of deterioration in each part of each fuel cell cogeneration system 2 is likely to vary. This tends to result in the timing of maintenance work being dispersed, and the efficiency of the maintenance work is likely to decrease. Therefore, in order to improve the efficiency of maintenance work, it is desirable that the power generation of the fuel cell cogeneration systems 2 being operated, i.e., the target power generation power TP, be uniform.

[0069] Furthermore, if the target power generation power TP of the fuel cell cogeneration plants 2 to be operated is made uniform, the target power generation power TP is likely to be less than the rated output. Therefore, it becomes easier to operate the fuel cell cogeneration plants 2 at less than the rated output (partial load operation). The fuel cell cogeneration plants 2 (specifically, fuel cells FC) have higher power generation efficiency when operated at partial load than when operated at rated output (full load operation). In other words, to make it easier to improve power generation efficiency, it is desirable that the target power generation power TP of the fuel cell cogeneration plants 2 to be operated is uniform.

[0070] Furthermore, in order to equalize the target power generation power TP while reliably ensuring the number of operating units 2N required to cover the power demand of the load 102, it is desirable to equalize the target power generation power TP based on the number of operating units 2N. From this perspective, as in this embodiment, it is desirable that the control method for the fuel cell power generation system 1 includes equalizing the target power generation power TP of the fuel cell power generators FCG (fuel cell cogeneration systems 2 in this embodiment) to be operated based on the number of operating units 2N.

[0071] In a configuration in which the state of each fuel cell power generator FCG includes an operating time 2T, operating one with a shorter operating time 2T is more likely to suppress an increase in the variation in the operating time 2T than one with a longer operating time 2T. In other words, an increase in the variation in the state of each fuel cell power generator FCG is more likely to be suppressed. Therefore, from the perspective of making it easier to suppress an increase in the variation in the operating time 2T (state) of each fuel cell power generator FCG, the following configuration is desirable. In other words, as in this embodiment, the control method for the fuel cell power generation system 1 desirably includes preferentially operating a fuel cell power generator FCG with a short operating time 2T among the multiple fuel cell power generators FCG.

[0072] From the viewpoint of keeping the variation in the operating time 2T of each fuel cell power generator FCG within a certain range and reliably suppressing an increase in the variation, the following configuration is desirable: That is, as in this embodiment, the control method for the fuel cell power generator system 1 desirably includes changing the fuel cell power generator FCG to be operated when any of the differences in the operating time 2T of each fuel cell power generator FCG reaches a predetermined threshold value.

[0073] As described above, as the fuel cell cogeneration system 2 operates, deterioration of each part of the fuel cell cogeneration system 2 progresses. In particular, as deterioration of the fuel cell FC progresses, for example, the fuel cell FC may fail to generate electricity. Note that the times when the fuel cell FC may fail to generate electricity are not limited to those described above. For example, the fuel cell FC may fail to generate electricity when the outside air temperature is high. Below, we will explain the control method for the fuel cell power generation system 1, which is related to the operation method of the fuel cell cogeneration system 2 when the fuel cell FC is failing to generate electricity. Figure 5 is a flowchart showing the flow when the number 2N of operating fuel cell cogeneration systems 2 is changed when the fuel cell FC is failing to generate electricity.

[0074] In step S10, for example, it is assumed that the number 2N of operating fuel cell cogeneration units 2 is two. Furthermore, it is assumed that a first fuel cell cogeneration unit 2A and a second fuel cell cogeneration unit 2B are selected as operation targets. In the first fuel cell cogeneration unit 2A, the first fuel cell FC1 is generating power at the target power generation power TP output from the operation control unit 3a (see FIG. 1 for both). In the second fuel cell cogeneration unit 2B, the second fuel cell FC2 (see FIG. 1) is generating power at a power lower than the target power generation power TP output from the operation control unit 3a. In other words, it is assumed that a power generation failure has occurred in the second fuel cell FC2. It is also assumed that the operation of the third fuel cell cogeneration unit 2C has been stopped (as instructed by the operation control unit 3a).

[0075] In step S11, the operation control unit 3a determines whether or not a power generation malfunction has occurred in at least one of the fuel cells FC included in the operating fuel cell cogeneration system 2. In this embodiment, this determination is made by determining whether or not the fuel cell FC of each fuel cell cogeneration system 2 is generating power at a level equal to or greater than the target power generation power TP. For example, if the fuel cell FC is generating power at a level equal to or greater than the target power generation power TP, it is determined that the fuel cell FC is not generating power at a level equal to or greater than the target power generation power TP, i.e., the fuel cell FC is normal. If the fuel cell FC is generating power at a level lower than the target power generation power TP, it is determined that the fuel cell FC is generating power at a level equal to or less than the target power generation power TP.

[0076] If a power generation failure has occurred in at least one of the fuel cells FC included in the operating fuel cell cogeneration system 2 (Yes in step S11), the process proceeds to the next step S12. If a power generation failure has not occurred in any of the fuel cells FC included in the operating fuel cell cogeneration system 2 (No in step S11), the operation control unit 3a continues the above determination.

[0077] In step S12, the operation control unit 3a determines whether the number 2N of operating fuel cell cogeneration systems 2 (calculated in step S2 of FIG. 3) is less than the number of installed systems. If the number 2N of operating systems is less than the number of installed systems (Yes in step S12), the process proceeds to the next step, S13. If the number 2N of operating systems is not less than the number of installed systems, that is, if the number 2N of operating systems is equal to or greater than the number of installed systems (No in step S12), the process described below (increasing the number 2N of operating systems) cannot be performed, and the process ends.

[0078] In step S13, the operation control unit 3a increases the number of operating units 2N. In this embodiment, the number of operating units 2N increases from two to three. That is, the control method for the fuel cell power generation system 1 of this embodiment includes increasing the number of operating units 2N when a power generation failure occurs in the fuel cell FC of the fuel cell power generation unit FCG (fuel cell cogeneration unit 2 in this embodiment) being operated. Note that the increase in the number of operating units 2N is not limited to one unit, and may be, for example, two or more units. When the number of operating units 2N increases, processing proceeds to the next step S14.

[0079] In step S14, the operation control unit 3a recalculates the target power generation power TP of the fuel cell cogeneration plant 2 based on the increased number 2N of operating units (three in this embodiment) and the power demand of the load 102. As with the calculation of the target power generation power TP shown in step S3 of FIG. 3, the target power generation power TP is calculated by dividing the power demand of the load 102 by the (increased) number 2N of operating units. Therefore, if the power demand of the load 102 remains the same, the target power generation power TP will decrease because the number 2N of operating units has increased. The recalculated target power generation power TP is output to the fuel cell cogeneration plant 2 to be operated among the multiple fuel cell cogeneration plants 2. Power generation by the fuel cells FC is performed in each of the fuel cell cogeneration plants 2 to be operated based on this target power generation power TP. Once the target power generation power TP has been recalculated and each fuel cell FC has generated power, the process proceeds to the next step S15.

[0080] In step S15, the operation control unit 3a determines whether the total of the power generated by each fuel cell FC (i.e., the power generated by each fuel cell cogeneration system 2) is equal to or greater than the power demand of the load 102. If the total of the power generated by each fuel cell FC is equal to or greater than the power demand of the load 102 (Yes in step S15), this flowchart ends. In other words, even if there is a fuel cell FC that is generating power at a level lower than the reduced target power generation power TP, if the total of the power generated by each fuel cell FC is equal to or greater than the power demand of the load 102, it is determined that the power demand of the load 102 is being met, and the increase in the number of operating units 2N is stopped.

[0081] If the total power generation of each fuel cell FC is not equal to or greater than the power demand of the load 102 (No in step S15), the process returns to step S11. Therefore, the processes of steps S11 to S15 are repeated until the total power generation of each fuel cell FC is equal to or greater than the power demand of the load 102. As a result, the target power generation power TP is gradually reduced, so that even a fuel cell FC that has experienced a power generation failure can generate power at the target power generation power TP. If a fuel cell FC that has experienced a power generation failure generates power at the target power generation power TP, all of the fuel cell cogeneration systems 2 that are in operation will operate at the target power generation power TP. Therefore, it is possible to reliably prevent the total power generation power of the fuel cell cogeneration systems 2 that are in operation from being insufficient for the power demand of the load 102.

[0082] It is desirable that the power demand of the load 102 be reliably met even if a power generation failure occurs in the fuel cell FC of the fuel cell cogeneration system 2 to be operated. In this regard, as in this embodiment, it is desirable that the control method for the fuel cell power generation system 1 includes increasing the number of operating units 2N when a power generation failure occurs in the fuel cell FC of the fuel cell power generation system FCG (fuel cell cogeneration system 2 in this embodiment) to be operated.

[0083] [3-3. Modified example of the method for selecting the operation target] A modified example of the method for selecting an operating target will be described with reference to Fig. 6. Fig. 6 is an explanatory diagram illustrating a modified example of the method for selecting an operating target. Fig. 6 illustrates an example of changes in the power generation time FCT of the fuel cells FC of the fuel cell cogeneration system 2. In detail, the power generation time FC1T of the first fuel cell FC1 is shown by a solid line, the power generation time FC2T of the second fuel cell FC2 is shown by a dashed line, and the power generation time FC3T of the third fuel cell FC3 is shown by a dashed-dotted line. Also in Fig. 6, the number 2N of operating fuel cell cogeneration systems 2 is shown by a two-dot chain line.

[0084] The method of selecting an operation target shown in Fig. 6 is the same as the method of selecting an operation target shown in Fig. 4, except that the power generation time FCT of the fuel cell FC is used as the state of the fuel cell cogeneration system 2. In other words, the power generation time FCT of the fuel cell FC is another example of the state of the fuel cell cogeneration system 2. In other words, the state of each fuel cell power generation system FCG (fuel cell cogeneration system 2 in this embodiment) includes the power generation time FCT of the fuel cell FC of each fuel cell power generation system FCG.

[0085] In the modified example, the power generation time FCT of each fuel cell FC means the cumulative power generation time since maintenance work was performed on each fuel cell FC. Therefore, the power generation time FCT of each fuel cell FC is reset (returned to zero) every time maintenance work is performed.

[0086] At time t0A, of the power generation times FCT of the fuel cells FC, the power generation time FC1T of the first fuel cell FC1 is the shortest, and the power generation time FC3T of the third fuel cell FC3 is the longest.

[0087] In the period from time t0A to time t1A, the number of operating vehicles 2N is the first number of operating vehicles 2N1 (0 in the modified example). In this case, the power demand of the load 102 is zero, as in Fig. 4 .

[0088] At time t1A, the power demand of the load 102 increases (slightly) from zero. As a result, the number of operating units 2N calculated by the operation control unit 3a (see FIG. 1) becomes the second number of operating units 2N2 (one unit in the modified example). Here, the operation control unit 3a selects the fuel cell cogeneration units 2 corresponding to the second number of operating units 2N2 as the operation targets. In the modified example, the operation control unit 3a selects, from among the fuel cell cogeneration units 2, the first fuel cell cogeneration unit 2A whose fuel cell FC power generation time FCT is shortest at time t1A as the operation target.

[0089] A target power generation output TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A selected for operation. The target power generation output TP at this time is calculated by dividing the power demand of the load 102 by the second number of operating units 2N2 (1 in the modified example). The first fuel cell cogeneration unit 2A is operated based on this target power generation output TP, i.e., the first fuel cell FC1 generates power. As a result, the power generation time FC1T of the first fuel cell FC1 gradually increases (see, for example, the period from time t1A to time t2A).

[0090] At time t2A, the power demand of the load 102 increases from the power demand of the load 102 at time t1A, for example. As a result, the number of operating units 2N becomes the third number of operating units 2N3 (two units in the modified example). Here, the operation control unit 3a selects the fuel cell cogeneration units 2 equivalent to the third number of operating units 2N3 as the operation targets. In the modified example, the operation control unit 3a selects the fuel cell cogeneration units 2 in order starting from the fuel cell cogeneration unit 2 with the shortest power generation time FCT of the fuel cell FC at time t2A. That is, the operation control unit 3a selects the first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B as the operation targets. That is, of the multiple fuel cell cogeneration units 2, the fuel cell cogeneration unit 2 with the shortest power generation time FCT of the fuel cell FC is preferentially selected as the operation target.

[0091] A target power generation output TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B selected for operation. The target power generation output TP is calculated by dividing the power demand of the load 102 by the third number of operating units 2N3 (two in the modified example). The first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B are operated based on this target power generation output TP, i.e., the first fuel cell FC1 and the second fuel cell FC2 generate power, respectively. As a result, the power generation time FC1T of the first fuel cell FC1 and the power generation time FC2T of the second fuel cell FC2 each gradually increase (see, for example, the period from time t2A to time t3A).

[0092] At time t3A, the difference between the power generation time FC1T of the first fuel cell FC1 and the power generation time FC3T of the (stopped) third fuel cell FC3 reaches a predetermined power generation time threshold (e.g., 100 hours). Here, the operation control unit 3a excludes the first fuel cell cogeneration unit 2A having the first fuel cell FC1 from the operation targets, and selects the third fuel cell cogeneration unit 2C having the third fuel cell FC3 as the operation target.

[0093] The operation control unit 3a may change the operation target in other cases besides those described above. For example, it may change when the difference between the power generation time FC1T of the first fuel cell FC1 and the power generation time FC2T of the second fuel cell FC2 reaches the power generation time threshold. It may also change when the difference between the power generation time FC2T of the second fuel cell FC2 and the power generation time FC3T of the third fuel cell FC3 reaches the power generation time threshold.

[0094] The system controller 3 (operation control unit 3a) outputs a target power generation output TP to the third fuel cell cogeneration unit 2C selected for operation. The target power generation output TP at this time is the same as the target power generation output TP calculated at time t2A. The third fuel cell cogeneration unit 2C is operated, i.e., the third fuel cell FC3 generates power, based on this target power generation output TP. As a result, the power generation time FC3T of the third fuel cell FC3 gradually increases (see, for example, the period from time t3A to time t4A).

[0095] Meanwhile, operation of the first fuel cell cogeneration system 2A, i.e., power generation by the first fuel cell FC1, is stopped. As a result, the power generation time FC1T of the first fuel cell FC1 no longer increases. Therefore, the power generation time FC1T of the first fuel cell FC1 from time t3A onwards (more specifically, the period from time t3A to time t4A) remains the same as the power generation time FC1T at time t3A.

[0096] At time t4A, the power demand of the load 102 increases from the power demand of the load 102 at time t2A, for example. As a result, the number of operating units 2N becomes the fourth number of operating units 2N4 (three in the modified example). Here, the operation control unit 3a selects the fourth number of operating units 2N4 of fuel cell cogeneration units 2 as the operation targets. In the modified example, since the fourth number of operating units 2N4 is the same as the number of installed units, the operation control unit 3a selects the first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C as the operation targets. In other words, all of the multiple fuel cell cogeneration units 2 in the fuel cell power generation system 1 are selected as operation targets.

[0097] A target power generation output TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C selected for operation. The target power generation output TP is calculated by dividing the power demand of the load 102 by the fourth number of operating units 2N4 (three in the modified example). The first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C are each operated based on this target power generation output TP. That is, the first fuel cell FC1, the second fuel cell FC2, and the third fuel cell FC3 each generate power. As a result, the power generation time FC1T of the first fuel cell FC1, the power generation time FC2T of the second fuel cell FC2, and the power generation time FC3T of the third fuel cell FC3 each gradually increase (see the period after time t4A).

[0098] By giving priority to the operation of the fuel cell cogeneration system 2 with a short power generation time FCT of the fuel cell FC, the increase in the variation in the power generation time FCT is suppressed even when the power generation time FCT and the operating time 2T of the fuel cell cogeneration system 2 increase separately. This prevents the timing of maintenance work for each fuel cell FC from being dispersed, and prevents a decrease in the efficiency of maintenance work in the fuel cell power generation system 1. Note that, for example, an example of an example of an example of an example of an example of an example of an example of a case where the power generation time FCT and the operating time 2T increase separately is when the fuel cell cogeneration system 2 is operated while power generation by the fuel cell FC is stopped. That is, in this embodiment, an example of ... That is, as in the modified example, the operating time 2T of the fuel cell power generator FCG (fuel cell cogeneration system 2 in the modified example) preferably includes the power generation time FCT of the fuel cell FC.

[0099] Another modified example of the method for selecting an operating target will be described with reference to Fig. 7. Fig. 7 is an explanatory diagram illustrating another modified example of the method for selecting an operating target. Fig. 7 illustrates an example of changes in the accumulated power generation amount FCa of the fuel cell FC. In detail, the accumulated power generation amount FC1a of the first fuel cell FC1 is shown by a solid line, the accumulated power generation amount FC2a of the second fuel cell FC2 is shown by a dashed line, and the accumulated power generation amount FC3a of the third fuel cell FC3 is shown by a dashed-dotted line. Also in Fig. 7, the number 2N of operating fuel cell cogeneration systems 2 is shown by a two-dot chain line.

[0100] The method of selecting an operation target shown in Fig. 7 is the same as the method of selecting an operation target shown in Fig. 4 or 6, except that the accumulated power generation amount FCa of the fuel cell FC, which is an example of the deterioration degree FCd of the fuel cell FC, is used as the state of the fuel cell cogeneration system 2. In other words, the deterioration degree FCd of the fuel cell FC is another example of the state of the fuel cell cogeneration system 2. In other words, the state of each fuel cell power generation system FCG (fuel cell cogeneration system 2 in this embodiment) includes the deterioration degree FCd of each fuel cell FC, and this deterioration degree FCd includes the accumulated power generation amount FCa. Note that the smaller the accumulated power generation amount FCa, the smaller the deterioration degree FCd.

[0101] In other modified examples, the integrated power generation amount FCa of each fuel cell FC means the cumulative amount of power generated since maintenance work was performed on each fuel cell FC. Therefore, the integrated power generation amount FCa of each fuel cell FC is reset (returned to zero) every time maintenance work is performed.

[0102] At time t0B, of the integrated power generation amounts FCa of the fuel cells FC, the integrated power generation amount FC1a of the first fuel cell FC1 is the smallest, and the integrated power generation amount FC3a of the third fuel cell FC3 is the largest.

[0103] In the period from time t0B to time t1B, the number of operating vehicles 2N is the first number of operating vehicles 2N1 (0 in other modified examples). In this case, as in Fig. 4 etc., the power demand of the load 102 is zero.

[0104] At time t1B, the power demand of the load 102 increases (slightly) from zero. As a result, the number of operating units 2N calculated by the operation control unit 3a (see FIG. 1) becomes the second number of operating units 2N2 (1 unit in other modified examples). Here, the operation control unit 3a selects the fuel cell cogeneration units 2 equivalent to the second number of operating units 2N2 as the operation targets. In other modified examples, the operation control unit 3a selects, from among the fuel cell cogeneration units 2, the first fuel cell cogeneration unit 2A that has the smallest accumulated power generation amount FCa of the fuel cell FC at time t1B as the operation target.

[0105] A target power generation output TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A selected for operation. The target power generation output TP at this time is calculated by dividing the power demand of the load 102 by the second number of operating units 2N2 (1 in other modified examples). The first fuel cell cogeneration unit 2A is operated, i.e., the first fuel cell FC1 generates power, based on this target power generation output TP. As a result, the integrated power generation amount FC1a of the first fuel cell FC1 gradually increases (see, for example, the period from time t1B to time t2B). In other words, the control method for the fuel cell power generation system 1 in this modified example includes preferentially operating a fuel cell power generation unit FCG with a smaller degradation level FCd among multiple fuel cell power generation units FCG (fuel cell cogeneration units 2 in this embodiment).

[0106] At time t2B, the power demand of the load 102 increases from the power demand of the load 102 at time t1B, for example. As a result, the number of operating units 2N becomes the third number of operating units 2N3 (two units in other modified examples). Here, the operation control unit 3a selects the fuel cell cogeneration units 2 equivalent to the third number of operating units 2N3 as the operation targets. In other modified examples, the operation control unit 3a selects the fuel cell cogeneration units 2 in descending order of the integrated power generation amount FCa of the fuel cell FC at time t2B. That is, the operation control unit 3a selects the first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B as the operation targets. That is, of the multiple fuel cell cogeneration units 2, the fuel cell cogeneration unit 2 with the lowest integrated power generation amount FCa of the fuel cell FC is preferentially selected as the operation target.

[0107] A target power generation output TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B selected for operation. The target power generation output TP is calculated by dividing the power demand of the load 102 by the third number of operating units 2N3 (two in other variants). The first fuel cell cogeneration unit 2A and the second fuel cell cogeneration unit 2B are operated based on this target power generation output TP, i.e., the first fuel cell FC1 and the second fuel cell FC2 generate power, respectively. As a result, the integrated power generation output FC1a of the first fuel cell FC1 and the integrated power generation output FC2a of the second fuel cell FC2 gradually increase (see, for example, the period from time t2B to time t3B).

[0108] At time t3B, the difference between the integrated power generation amount FC1a of the first fuel cell FC1 and the integrated power generation amount FC3a of the (stopped) third fuel cell FC3 reaches a predetermined integrated power generation amount threshold. At this time, the operation control unit 3a excludes the first fuel cell cogeneration unit 2A having the first fuel cell FC1 from the operation targets, and selects the third fuel cell cogeneration unit 2C having the third fuel cell FC3 as the operation target.

[0109] The operation control unit 3a may change the operating target in other cases besides those described above. For example, it may change when the difference between the integrated power generation amount FC1a of the first fuel cell FC1 and the integrated power generation amount FC2a of the second fuel cell FC2 reaches the integrated power generation amount threshold. It may also change when the difference between the integrated power generation amount FC2a of the second fuel cell FC2 and the integrated power generation amount FC3a of the third fuel cell FC3 reaches the integrated power generation amount threshold.

[0110] The system controller 3 (operation control unit 3a) outputs a target power generation output TP to the third fuel cell cogeneration unit 2C selected for operation. The target power generation output TP at this time is the same as the target power generation output TP calculated at time t2B. The third fuel cell cogeneration unit 2C is operated, i.e., the third fuel cell FC3 generates power, based on this target power generation output TP. As a result, the integrated power generation output FC3a of the third fuel cell FC3 gradually increases (see, for example, the period from time t3B to time t4B).

[0111] Meanwhile, operation of the first fuel cell cogeneration system 2A, i.e., power generation by the first fuel cell FC1, is stopped. As a result, the integrated power generation amount FC1a of the first fuel cell FC1 stops increasing. Therefore, the integrated power generation amount FC1a of the first fuel cell FC1 from time t3B onwards (specifically, the period from time t3B to time t4B) remains the same as the integrated power generation amount FC1a at time t3B.

[0112] At time t4B, the power demand of the load 102 increases from the power demand of the load 102 at time t2B, for example. As a result, the number of operating units 2N becomes the fourth number of operating units 2N4 (three in other modified examples). Here, the operation control unit 3a selects the fourth number of operating units 2N4 of fuel cell cogeneration units 2 as the operation targets. In other modified examples, the fourth number of operating units 2N4 is the same as the number of installed units, so the operation control unit 3a selects the first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C as the operation targets. In other modified examples, all of the multiple fuel cell cogeneration units 2 in the fuel cell power generation system 1 are selected as operation targets.

[0113] A target power generation amount TP is output from the system controller 3 (operation control unit 3a) to the first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C selected for operation. The target power generation amount TP is calculated by dividing the power demand of the load 102 by the fourth number of operating units 2N4 (three in other variants). The first fuel cell cogeneration unit 2A, the second fuel cell cogeneration unit 2B, and the third fuel cell cogeneration unit 2C are each operated based on this target power generation amount TP. That is, the first fuel cell FC1, the second fuel cell FC2, and the third fuel cell FC3 each generate power. As a result, the integrated power generation amount FC1a of the first fuel cell FC1, the integrated power generation amount FC2a of the second fuel cell FC2, and the integrated power generation amount FC3a of the third fuel cell FC3 each gradually increase (see the period from time t4B onwards).

[0114] In a configuration in which the state of each fuel cell power generator FCG (fuel cell cogeneration system 2 in this embodiment) includes the degradation degree FCd of each fuel cell FC, increasing the variation in the degradation degree FCd can be more easily suppressed by giving priority to operation of the fuel cell power generator FCG with a smaller degradation degree FCd. Therefore, from the perspective of making it easier to suppress increasing variation in the degradation degree FCd of each fuel cell FC, the following configuration is desirable. That is, as in the other modified examples, the control method for the fuel cell power generation system 1 desirably includes giving priority to operation of the fuel cell power generator FCG with a smaller degradation degree FCd among the multiple fuel cell power generators FCG.

[0115] The degree of deterioration FCd of the fuel cell FC is difficult to estimate accurately, and therefore is difficult to use in the control method of the fuel cell power generation system 1. On the other hand, although the integrated power generation amount FCa of the fuel cell FC is different from the degree of deterioration FCd of the fuel cell FC itself, it has a good correspondence relationship with the degree of deterioration FCd of the fuel cell FC and is suitable for expressing the degree of deterioration FCd of the fuel cell FC. Furthermore, the integrated power generation amount FCa is easy to detect. Therefore, from the perspective of making it easier to use the degree of deterioration FCd of the fuel cell FC in the control method of the fuel cell power generation system 1, it is desirable that the degree of deterioration FCd of the fuel cell FC include the integrated power generation amount FCa of the fuel cell FC, as in the other modified examples.

[0116] [4. Notes] The control method, control program 32a, and fuel cell power generation system 1 described in this embodiment can also be expressed as a control method, control program, and fuel cell power generation system for a fuel cell power generation system shown in the following supplementary notes.

[0117] The control method for the fuel cell power generation system of appendix (1) is A control method for a fuel cell power generation system including a plurality of fuel cell power generation devices each having a fuel cell, comprising: The method includes determining an operating mode of each of the fuel cell power generation devices based on the power demand of a load electrically connected to each of the fuel cell power generation devices and the state of each of the fuel cell power generation devices.

[0118] A control method for a fuel cell power generation system according to claim 2, wherein the control method according to claim 1 further comprises: The method includes calculating the number of fuel cell power generation systems in operation based on the power demand of the load.

[0119] A control method for a fuel cell power generation system according to claim 3, wherein the control method according to claim 2 further comprises: The method includes increasing the number of operating units when a power generation failure occurs in the fuel cells of the fuel cell power generation system being operated.

[0120] The control method for a fuel cell power generation system according to supplementary note (4) is the control method according to supplementary note (2) or (3), The method includes making the target power generation levels of the fuel cell power generation devices to be operated uniform based on the number of devices in operation.

[0121] The control method for a fuel cell power generation system according to Supplementary Note (5) is the control method according to any one of Supplementary Note (1) to (4), the state of each fuel cell power generation device includes an operating time of each fuel cell power generation device; The method includes giving priority to operation of the fuel cell power generation device having the shortest operating time among the plurality of fuel cell power generation devices.

[0122] A control method for a fuel cell power generation system according to claim 6, wherein the control method according to claim 5, When any of the differences in the operation times of the fuel cell power generation apparatuses reaches a predetermined threshold, the fuel cell power generation apparatus to be operated is changed.

[0123] The control method for a fuel cell power generation system according to supplementary note (7) is the control method according to supplementary note (5) or (6), The operating time includes the power generation time of the fuel cell.

[0124] A control method for a fuel cell power generation system according to claim (8) is the control method according to any one of claims (1) to (7), the state of each fuel cell power generation device includes a degree of deterioration of each fuel cell; The method includes operating the fuel cell power generation device with the least degree of deterioration among the plurality of fuel cell power generation devices with priority.

[0125] A control method for a fuel cell power generation system according to claim 9, wherein the control method according to claim 8, The deterioration level includes the integrated power generation amount of the fuel cell.

[0126] A control method for a fuel cell power generation system according to claim (10) is the control method according to any one of claims (1) to (9), The fuel cell power generation system includes a fuel cell cogeneration system that recovers waste heat generated by the power generation of the fuel cell.

[0127] The control program for the fuel cell power generation system of supplementary note (11) causes at least one arithmetic device to execute the control method according to any one of supplementary notes (1) to (10).

[0128] The fuel cell power generation system of Appendix (12) A fuel cell power generation system including a plurality of fuel cell power generation devices each having a fuel cell, An operation control unit is provided that determines the operation mode of each fuel cell power generation device based on the power demand of a load electrically connected to each fuel cell power generation device and the state of each fuel cell power generation device.

[0129] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these, and the invention can be expanded or modified without departing from the spirit of the invention. [Industrial Applicability]

[0130] The present invention can be used in, for example, fuel cell power generation systems for industrial use. [Explanation of symbols]

[0131] 1. Fuel cell power generation system 2. Fuel cell cogeneration equipment 2N Number of operating vehicles 2T Operating time 3a Operation control unit 31 Arithmetic unit 32a Control Program 102 Load FC fuel cell FCG fuel cell power generation equipment FCT power generation time FCa cumulative power generation FCd Degradation TP target power generation

Claims

1. A control method for a fuel cell power generation system including a plurality of fuel cell power generation devices each having a fuel cell, comprising: A control method for a fuel cell power generation system, comprising determining an operating mode of each of the fuel cell power generation devices based on the power demand of a load electrically connected to each of the fuel cell power generation devices and the state of each of the fuel cell power generation devices.

2. 2. The control method for a fuel cell power generation system according to claim 1, further comprising calculating the number of operating fuel cell power generation apparatuses based on the power demand of the load.

3. 3. The control method for a fuel cell power generation system according to claim 2, further comprising increasing the number of operating units when a power generation failure occurs in the fuel cell of the fuel cell power generation device being operated.

4. 3. The control method for a fuel cell power generation system according to claim 2, further comprising: making the target generated power of the fuel cell power generation devices to be operated uniform based on the number of the devices in operation.

5. the state of each fuel cell power generation device includes an operating time of each fuel cell power generation device; 2. The control method for a fuel cell power generation system according to claim 1, further comprising giving priority to operation of the fuel cell power generation device having the shortest operating time among the plurality of fuel cell power generation devices.

6. 6. A control method for a fuel cell power generation system as described in claim 5, including changing the fuel cell power generation device to be operated when any of the differences in the operating times of each of the fuel cell power generation devices reaches a predetermined threshold value.

7. The method for controlling a fuel cell power generation system according to claim 5 , wherein the operating time includes a power generation time of the fuel cell.

8. the state of each fuel cell power generation device includes a degree of deterioration of each fuel cell; 2. The control method for a fuel cell power generation system according to claim 1, further comprising giving priority to operation of the fuel cell power generation device with the least degree of deterioration among the plurality of fuel cell power generation devices.

9. 9. The control method for a fuel cell power generation system according to claim 8, wherein the degree of deterioration includes an integrated amount of power generated by the fuel cell.

10. 2. The control method for a fuel cell power generation system according to claim 1, wherein the fuel cell power generation system includes a fuel cell cogeneration system that recovers waste heat generated by the power generation of the fuel cell.

11. A control program for a fuel cell power generation system, which causes at least one arithmetic device to execute the control method according to any one of claims 1 to 10.

12. A fuel cell power generation system including a plurality of fuel cell power generation devices each having a fuel cell, a fuel cell power generation system comprising an operation control unit that determines an operation mode of each of the fuel cell power generation devices based on the power demand of a load electrically connected to each of the fuel cell power generation devices and the state of each of the fuel cell power generation devices;

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