Fuel cell system and method for operating fuel cell system

Abstract

A fuel cell system (100) according to the present disclosure comprises: a plurality of fuel cell units (10); and an operation control device (20) that controls power generated by the plurality of fuel cell units (10) on the basis of an operation plan. Each of the plurality of fuel cell units (10) is provided with a control unit (11) that controls the operation of the fuel cell unit (10). The control unit (11) operates the fuel cell unit (10) in a low power mode during test operation of the fuel cell unit (10). The generated power of the fuel cell unit (10) in the low power mode is smaller than the minimum generated power during normal operation of the fuel cell unit (10).

Description

Fuel cell system and method for operating a fuel cell system

[0001] The present disclosure relates to a fuel cell system and a method for operating a fuel cell system.

[0002] As a configuration for obtaining a high power generation amount, a fuel cell system including a plurality of fuel cell units has been proposed. In such a fuel cell system including a plurality of fuel cell units, for example, as disclosed in Patent Document 1, the operation of the plurality of fuel cell units is controlled based on a power generation plan (i.e., an operation plan).

[0003] Japanese Unexamined Patent Application Publication No. 2023 - 121517

[0004] In a fuel cell system including a plurality of fuel cell units, for each fuel cell unit, maintenance is performed according to the cumulative operation time or the like, or replacement with a new unit is performed due to a defect such as a failure. After such maintenance or after new installation, before starting the normal operation of the fuel cell unit, the operation may be confirmed by a test run.

[0005] However, when controlling the power generation power of a plurality of fuel cell units based on an operation plan, a difference from the power according to the operation plan may occur due to the generation of power generation power during the test run, which may cause a problem. That is, when a fuel cell unit during a test run is included in a plurality of fuel cell units, the fuel cell system may supply power higher than the power determined in the operation plan as the power of the entire system, which may cause a problem.

[0006] However, a technique for operating a fuel cell system considering the presence of a fuel cell unit to be tested has not been proposed yet.

[0007] Therefore, the present disclosure provides a technique suitable for keeping the output of a fuel cell system within the allowable range of the power generation power planned by an operation plan even when a fuel cell unit during a test run is included in a fuel cell system including a plurality of fuel cell units.

[0008] A first aspect of the present disclosure provides a fuel cell system comprising: a plurality of fuel cell units; and an operation control device that controls the power generated by the plurality of fuel cell units based on an operation plan, wherein each of the plurality of fuel cell units is equipped with a control unit that controls the operation of the fuel cell unit, and the control unit operates the fuel cell unit in a low-power mode during trial operation, and the power generated by the fuel cell unit in the low-power mode is less than the minimum power generated during normal operation of the fuel cell unit.

[0009] A second aspect of this disclosure provides a method for operating a fuel cell system comprising a plurality of fuel cell units, the method comprising: (I) controlling the power generated by the plurality of fuel cell units based on an operation plan; and (II) if the plurality of fuel cell units include a fuel cell unit undergoing trial operation, operating the trial fuel cell unit in a low-power mode in which the power generated is less than the minimum power generated during normal operation of the fuel cell unit.

[0010] The technology relating to this disclosure is suitable for keeping the output of a fuel cell system within the permissible range of power generation planned by the operation plan, even when a fuel cell unit being commissioned is included in a fuel cell system comprising multiple fuel cell units.

[0011] Configuration diagram of the fuel cell system according to Embodiment 1 Flowchart of the trial run when the fuel cell unit is continuously operated in low power mode during the trial run of the fuel cell system according to Embodiment 1 Flowchart of the trial run when the low power mode is canceled in response to power demands during the trial run of the fuel cell system according to Embodiment 1 Configuration diagram of the fuel cell system according to Embodiment 2 Flowchart of the trial run of the fuel cell system according to Embodiment 2

[0012] The embodiments will be described in detail below with reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art.

[0013] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0014] (Embodiment 1) Hereinafter, an embodiment will be described with reference to Figures 1 to 3.

[0015] [1-1. Configuration] Figure 1 is a configuration diagram of a fuel cell system according to Embodiment 1. As shown in Figure 1, the fuel cell system 100 according to Embodiment 1 comprises a plurality of fuel cell units 10 and an operation control device 20. The operation control device 20 controls the power generated by the plurality of fuel cell units 10 based on an operation plan. Each of the plurality of fuel cell units 10 is equipped with a control unit 11 that controls the operation of the fuel cell unit 10.

[0016] The fuel cell system 100 is connected to a load 300 and supplies the generated electricity to the load 300. The load 300 is installed in, for example, a factory, hospital, school, commercial facility, etc.

[0017] Each of the multiple fuel cell units 10 includes a control unit 11, a fuel cell stack 12, and auxiliary equipment (not shown) necessary to operate the fuel cell stack 12. In Figure 1, the first fuel cell unit 101, the second fuel cell unit 102, the third fuel cell unit 103, ... the nth fuel cell unit 10 n An example is shown in which n fuel cell units 10 (where n is an integer of 4 or more) are connected to each other.

[0018] Examples of fuel cells include polymer electrolyte membrane fuel cells, solid oxide fuel cells, phosphoric acid fuel cells, and molten carbonate fuel cells. Fuel gas and oxidizer gas are supplied to the fuel cell stack 12, and electricity is generated by the reaction of the fuel gas and oxidizer gas in the fuel cell stack 12. The fuel supplied to the fuel cell stack 12 is, for example, pure hydrogen. In this case, the fuel cell system 100 further includes a tank (not shown) in which pure hydrogen is stored. Hydrogen gas as fuel gas is supplied from this tank to the fuel cell stack 12. The fuel used in the fuel cell system 100 may also include hydrocarbon gases such as methane gas, propane gas, and butane gas. In this case, the fuel cell system 100 includes a reformer. Hydrogen-containing gas as fuel gas is produced from hydrocarbon gas in the reformer, and the hydrogen-containing gas is supplied to the fuel cell stack 12. Examples of fuels containing hydrocarbon gases are city gas and LPG.

[0019] The fuel cell unit 10 may be a fuel cell operating at its rated capacity, or a fuel cell capable of partial load operation. If the fuel cell unit 10 is a fuel cell operating at its rated capacity, it generates and outputs a predetermined amount of power during normal operation. If the fuel cell unit 10 is a fuel cell capable of partial load operation, it is provided with, for example, an adjustment function for adjusting the generated power within a predetermined range. In this case, during normal operation, the fuel cell unit 10 can adjust the generated power within a range from a preset minimum generated power to a preset maximum generated power, in response to fluctuations in power demand. Here, "normal operation" of the fuel cell unit 10 means operation in response to power requests from the operation control device 20 to the fuel cell unit 10 under normal circumstances, excluding special circumstances such as a power outage.

[0020] The control unit 11 of the fuel cell unit 10 is communicated with the operation control device 20 by wire or wireless means. For example, the control unit 11 performs the necessary controls for operating the fuel cell unit 10 according to the control signals received from the operation control device 20.

[0021] The control unit 11 is, for example, a computer equipped with a storage device that stores the program necessary for operating the fuel cell unit 10, and a processor that reads the program from the storage device and executes it.

[0022] The control unit 11 may incorporate information about the maintenance timing of the fuel cell unit 10, for example. The maintenance timing is determined, for example, by the cumulative operating time of the fuel cell unit 10. When it is time for maintenance of the fuel cell unit 10, the control unit 11 of the fuel cell unit 10 notifies the operation control device 20 of this fact.

[0023] As described above, the control unit 11 manages the operation of the fuel cell unit 10, including maintenance.

[0024] As described above, the operation control device 20 controls the power generated by the multiple fuel cell units 10 based on the operation plan. For example, the operation control device 20 issues instructions to the control unit 11 of each fuel cell unit 10 based on the operation plan of the entire fuel cell system 100, and controls the operation of each fuel cell unit 10.

[0025] The operation control device 20 is, for example, a computer equipped with a storage device that stores the program necessary for operating the fuel cell system 100, and a processor that reads the program from the storage device and executes it.

[0026] The operation control device 20 may, for example, have a predetermined operation plan for the entire fuel cell system 100 input to it. The operation plan input to the operation control device 20 includes a plan for a predetermined period of time regarding the total power generated by the entire fuel cell system 100. The operation plan may be, for example, a plan for one day, a plan for one week, or a plan for one month, and the period of the plan is not particularly limited.

[0027] The operation plan may include individual plans for the operation of each fuel cell unit 10 (for example, power generation, maintenance schedule, etc.). In that case, the operation control device 20 controls each fuel cell unit 10 by issuing instructions to the control unit 11 of each fuel cell unit 10 in accordance with the operation plan.

[0028] The operation plan may include only the plan for the entire fuel cell system 100 (for example, the total power generated by the entire system 100). In that case, the operation control device 20 may automatically decide on the operation of each fuel cell unit 10, for example by a program built into it, in order to achieve the operation plan for the entire system 100, and issue instructions to the control unit 11 of each fuel cell unit 10 to operate the fuel cell unit 10.

[0029] Here, the fuel cell unit 10 that the operation control device 20 targets for operation planning is the fuel cell unit 10 during normal operation. Therefore, fuel cell units 10 that are not performing normal operation, such as a fuel cell unit 10 that is stopped for maintenance or a fuel cell unit 10 that is undergoing trial operation after maintenance, are not included in the operation planning. Thus, trial operation of a fuel cell unit 10 is an operation outside of the operation planning.

[0030] [1-2. Operation] An example of the operation of the fuel cell system 100 will be described.

[0031] In the fuel cell system 100, the operation control device 20 controls the power generated by the multiple fuel cell units 10 based on the operation plan.

[0032] In a fuel cell system 100 equipped with multiple fuel cell units 10, maintenance is performed on each fuel cell unit 10 when a predetermined maintenance period arrives, for example, based on cumulative operating time, or when a unit is replaced with a new one due to a malfunction or other defect. When restarting a fuel cell unit 10 that has been stopped due to such maintenance, the operation of the fuel cell unit 10 is usually confirmed by a trial run. In the fuel cell system 100 according to Embodiment 1, during the trial run of the fuel cell unit 10, the control unit 11 operates the fuel cell unit 10 in low-power mode. The power generated by the fuel cell unit 10 in low-power mode is less than the minimum power generated during normal operation of the fuel cell unit 10. That is, in low-power mode, if the fuel cell unit 10 is a fuel cell operating at its rated capacity, the fuel cell unit 10 operates with a power generation less than the power generated at its rated capacity, and if the fuel cell unit 10 is a fuel cell capable of partial-load operation, it operates with a power generation less than the minimum power generated during normal operation that is set in advance.

[0033] In this disclosure, "low-power mode" means that when a fuel cell unit 10 that is stopped for maintenance or the like and excluded from the operation plan, i.e., a fuel cell unit 10 that does not have a power request from the operation control device 20, is commissioned, the commissioned operation is performed at a power output lower than the minimum power output during normal operation of the fuel cell unit 10. The difference between the state of the fuel cell unit 10 when no power is output to the outside at the very beginning of normal operation and the state of the fuel cell unit 10 being commissioned in low-power mode is, for example, whether or not power is being generated inside the unit 10. At the very beginning of normal operation, preparations for power generation are made, but power generation has not started. On the other hand, during commissioning in low-power mode, power is being generated inside the unit 10. Furthermore, since commissioning is performed continuously until operational verification is completed, commissioning in low-power mode continues for a certain period of time, whereas the very beginning of normal operation is a very short period until normal operation is reached, so that state does not continue.

[0034] As described above, in the fuel cell system 100 according to Embodiment 1, the power generated by the multiple fuel cell units 10 is controlled based on the operation plan. More specifically, the power generated by the entire fuel cell system 100 is planned, and the operation control device 20 controls the power generated by the fuel cell unit 10 during operation so as not to exceed the allowable range of the planned power generated. Here, it is common for an allowable range to be set for the planned power generated by the entire system. As an example, the allowable range can be considered to be within ±10% of the planned power generated. In the fuel cell system 100 according to Embodiment 1, by trial running the fuel cell unit 10 in low power mode, even if the fuel cell unit 10 that constitutes the multiple fuel cell units 10 that make up the fuel cell system 100 is being trial-run, the operation plan can be maintained so as not to exceed the upper limit of the allowable range of the planned power generated. In other words, even if a fuel cell unit 10 that is being trial-run is included, the output of the fuel cell system 100 can be kept within the allowable range of power generated planned by the operation plan. This prevents unplanned shutdowns of other fuel cell units during normal operation, which can occur when the power generated by the trial run of the fuel cell unit 10 causes the output of the fuel cell system 100 to exceed the upper limit of the planned allowable power generation range. As a result, the number of starts and stops can be reduced, and the deterioration of the fuel cell unit 10 can be suppressed.

[0035] In low-power mode, the control unit 11 may operate the fuel cell unit 10 in such a way that it generates power that does not exceed the power required to operate the fuel cell unit 10, and does not output power to the outside from the fuel cell unit 10. By controlling the operation of the fuel cell unit 10 undergoing trial operation to generate only the minimum necessary power without outputting power to the outside, even if the fuel cell unit 10 undergoing trial operation is included in the multiple fuel cell units 10 constituting the fuel cell system 100, the trial operation can be performed while maintaining the operation plan so as not to exceed the planned power generation. In other words, even if the fuel cell unit 10 undergoing trial operation is included, the output of the fuel cell system 100 can be more reliably kept within the allowable range of power generation planned by the operation plan. Therefore, it is possible to more reliably avoid unplanned shutdowns of other fuel cell units 10 during normal operation and suppress deterioration of the fuel cell unit 10. The power required to operate the fuel cell unit 10 is, for example, the power required to drive the auxiliary equipment of the fuel cell unit 10.

[0036] For example, when the trial run of the fuel cell unit 10 is completed, the control unit 11 notifies the operation control device 20 that the trial run has been completed. This allows the operation control device 20 to incorporate the fuel cell unit 10, which has completed the trial run and is now able to generate power normally, into the operation plan.

[0037] In the fuel cell system 100 according to Embodiment 1, the fuel cell unit 10 may be operated in low-power mode for the entire duration of the trial run, from the start of the trial run until the completion of the operation verification by the trial run, or the low-power mode may be deactivated during the trial run.

[0038] For example, if a fuel cell unit 10 undergoing trial operation receives a power request from the operation control device 20, the control unit 11 of that fuel cell unit 10 may operate the fuel cell unit 10 to output power based on the power request by releasing the low-power mode. This ensures that even if another fuel cell unit 10 stops unexpectedly due to an error or other reason during trial operation, the power output will not be insufficient to meet the power generation plan in the operation plan, and the operation plan can be maintained.

[0039] As described above, the operating method for the fuel cell system 100 according to Embodiment 1, that is, the operating method for the fuel cell system 100 equipped with a plurality of fuel cell units 10, includes: (I) controlling the power generated by the plurality of fuel cell units 10 based on the operation plan; and (II) if the plurality of fuel cell units 10 include a fuel cell unit 10 undergoing trial operation, operating the fuel cell unit 10 undergoing trial operation in a low-power mode in which the power generated is less than the minimum power generated during normal operation of the fuel cell unit 10. According to this operating method, even if the plurality of fuel cell units 10 constituting the fuel cell system 100 include a fuel cell unit 10 undergoing trial operation, trial operation can be performed while maintaining the operation plan so as not to exceed the upper limit of the allowable range of the planned power generation. In other words, even if a fuel cell unit 10 undergoing trial operation is included, the output of the fuel cell system 100 can be kept within the allowable range of power generation planned by the operation plan. This makes it possible to avoid unplanned shutdowns of other fuel cell units during normal operation due to the power generated by the trial operation of the fuel cell unit 10 causing the output of the fuel cell system 100 to exceed the upper limit of the allowable range of the planned power generation. As a result, the number of starts and stops can be reduced, and the deterioration of the fuel cell unit 10 can be suppressed.

[0040] In the above operating method, in (II) above, the fuel cell unit 10 operating in low-power mode may be operated so that the generated power does not exceed the power required to operate the fuel cell unit 10, and so that the generated power is not output from the fuel cell unit 10 to the outside. According to this operating method, even if the fuel cell system 100 includes a fuel cell unit 10 undergoing trial operation, the trial operation can be performed while maintaining the operating plan so as not to exceed the planned generated power. In other words, even if a fuel cell unit 10 undergoing trial operation is included, the output of the fuel cell system 100 can be more reliably kept within the allowable range of the generated power planned by the operating plan. Therefore, it is possible to more reliably avoid unplanned shutdowns of other fuel cell units during normal operation and suppress the deterioration of the fuel cell unit 10.

[0041] In the above operating method, when the trial run of the fuel cell unit 10 is completed in (II) above, the operation control device 20, which controls the power generation of the multiple fuel cell units 10, may be notified that the trial run has been completed. According to this operating method, the operation control device 20 can incorporate the fuel cell unit 10 that has completed the trial run and is now able to generate power normally into the operation plan.

[0042] In the above operating method, the fuel cell unit 10 may be operated in low-power mode for the entire duration from the start of the trial run until the end of the trial run when the operation has been confirmed, or the low-power mode may be deactivated during the trial run.

[0043] Figure 2 shows a flowchart of the trial run when the fuel cell unit 10 is continuously operated in low-power mode during the trial run. In this case, as shown in Figure 2, when the trial run of the fuel cell unit 10 is started, in step S1 the fuel cell unit 10 to be trialed is operated in low-power mode. In step S2 it is determined whether or not the operational verification by the trial run has been completed, and if the operational verification has been completed, the trial run is terminated.

[0044] In the above operation method, in the above (II), when the fuel cell unit 10 during the test run receives a power demand, the fuel cell unit 10 may be operated to cancel the low power mode and output power based on the power demand. According to this operation method, even if another fuel cell unit 10 stops unexpectedly due to an error or the like during the test run, the operation plan can be maintained without a shortage of the power output with respect to the power generation power planned in the operation plan.

[0045] Figure 3 shows a flowchart of the test run when canceling the low power mode in response to the power demand during the test run. In this case, as shown in Figure 3, when the test run of the fuel cell unit 10 is started, in step S11, the fuel cell unit 10 during the test run is operated in the low power mode. In step S12, it is determined whether the operation confirmation by the test run has been completed. If the operation confirmation has been completed, the test run is terminated. In step S12, if it is determined that the operation confirmation by the test run has not been completed, in step S13, it is determined whether there is a power demand for the fuel cell unit 10. If there is no power demand, the operation in the low power mode is continued. If there is a power demand, in step S14, the operation of the fuel cell unit 10 in the low power mode is canceled, and the fuel cell unit 10 outputs power based on the power demand. Thereafter, in step S15, it is determined whether the operation confirmation by the test run has been completed. If the operation confirmation has been completed, in step 16, it is determined whether there is a power demand for the fuel cell unit 10. If there is no power demand, the test run is terminated. In step 16, if there is a power demand, the test run is terminated but the operation is continued based on the power demand. That is, the operation directly shifts from the test run to the normal operation.

[0046] (Embodiment 2) Hereinafter, the embodiment will be described with reference to FIGS. 4 and 5.

[0047] [2-1. Configuration] FIG. 4 is a configuration diagram of the fuel cell system according to Embodiment 2. As shown in FIG. 4, the fuel cell system 200 according to Embodiment 2 further includes a power storage device 30 that stores the power generated by a plurality of fuel cell units 10 and a detector 40 that detects the power storage amount of the power storage device 30, in addition to the fuel cell system 100 according to Embodiment 1.

[0048] The power storage device 30 includes a storage battery 31. The storage battery is not limited to a specific type of storage battery. Examples of the storage battery are lithium ion batteries, redox flow batteries, and sodium sulfur batteries.

[0049] As shown in FIG. 4, the detector 40 may be provided in the power storage device 30, for example. The detector 40 notifies the operation control device 20 of the power storage amount in the power storage device 30, for example.

[0050] The details of the configurations of the fuel cell unit 10, the control unit 11, and the operation control device 20 are as described in Embodiment 1.

[0051] [2-2. Operation] An example of the operation of the fuel cell system 200 will be described. The operation of the fuel cell system 200 in which the power storage device 30 and the detector 40 are not involved is the same as that of the fuel cell system 100 according to Embodiment 1. That is, the fuel cell system 200 can perform all the operations that the fuel cell system 100 according to Embodiment 1 can perform, as described in Embodiment 1.

[0052] Hereinafter, in addition to the operation of the fuel cell system 100 according to Embodiment 1, the operations that the fuel cell system 200 according to Embodiment 2 can further perform will be described.

[0053] In the fuel cell system 200 according to Embodiment 2, when the fuel cell unit 10 is operating in low-power mode, if the amount of energy stored in the energy storage device 30 is less than a predetermined value, the power generated by the fuel cell unit 10 in low-power mode is stored in the energy storage device 30. This allows for trial operation while maintaining the operation plan so as not to exceed the upper limit of the planned allowable range of power generation, even when it is difficult to suppress the power generation to a small level during operation in low-power mode, or when the allowable range of power generation planned in the operation plan is very small. In other words, even under severe conditions such as when the fuel cell unit 10 is undergoing trial operation, and the allowable range of power generation in the operation plan is very small, the output of the fuel cell system 200 can be kept within the allowable range of power generation planned by the operation plan.

[0054] In the fuel cell system 200 according to Embodiment 2, when the fuel cell unit 10 is operating in low-power mode, if the amount of energy stored in the energy storage device 30 is above a predetermined value, the control unit 11 operates the fuel cell unit so as to generate power within a range that does not exceed the power required to operate the fuel cell unit 10, and so as not to output power to the outside from the fuel cell unit 10. As a result, even during trial operation when the energy storage device 30 cannot store energy, the power generated will not exceed the power planned by the operation control device 20, and trial operation can be performed while maintaining the plan.

[0055] The operating method for the fuel cell system 200 according to Embodiment 2 is, in addition to the operating method for the fuel cell system 100 including (I) and (II) described in Embodiment 1, further includes (III) storing the power generated by a plurality of fuel cell units in a power storage device 30, wherein in (II) above, if the amount of power stored in the power storage device 30 is less than a predetermined value, the power generated by the fuel cell unit 10 operating in low power mode is stored in the power storage device 30. With this operating method, even when it is difficult to suppress the power generated in low power mode, or when the allowable range of power generated planned in the operation plan is very small, trial operation can be performed while maintaining the operation plan so as not to exceed the upper limit of the allowable range of power generated. In other words, even when a fuel cell unit 10 undergoing trial operation is included, and under severe conditions such as a very small allowable range of power generated in the operation plan, the output of the fuel cell system 200 can be kept within the allowable range of power generated planned by the operation plan.

[0056] In the above operating method, in (II) above, if the amount of energy stored in the energy storage device 30 is above a predetermined value, the fuel cell unit 10 operating in low-power mode is operated so that the generated power does not exceed the power required to operate the fuel cell unit 10, and the generated power is not output to the outside from the fuel cell unit 10. With this operating method, even during trial operation when energy cannot be stored in the energy storage device 30, the generated power will not exceed the power planned by the operation control device 20, and trial operation can be performed while maintaining the plan.

[0057] Figure 5 shows a flowchart of the trial run of the fuel cell unit 10 for the fuel cell system 200 according to Embodiment 2. As shown in Figure 5, when the trial run of the fuel cell unit 10 is started, in step S21 the fuel cell unit 10 to be trialed is operated in low power mode. In step S22 it is determined whether the amount of energy stored in the energy storage device 30 is less than a predetermined value. If the amount of energy stored in the energy storage device 30 is less than a predetermined value, in step S23 the power generated by the fuel cell unit 10 operating in low power mode is stored in the energy storage device 30. If the amount of energy stored in the energy storage device 30 is not less than a predetermined value, that is, if the amount of energy stored in the energy storage device 30 is greater than or equal to a predetermined value, in step S24 the fuel cell unit 10 operating in low power mode is operated so that the power generated does not exceed the power required to operate the fuel cell unit 10, and the power generated is not output to the outside from the fuel cell unit 10. After that, in step S25 it is determined whether the operation confirmation by trial run has been completed. If the operational check is complete, the trial run will end. If the operational check is not complete, the trial run will continue in low-power mode.

[0058] (Other Embodiments) As described above, Embodiments 1 and 2 have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these and can be applied to embodiments that have been modified, replaced, added, omitted, etc. Furthermore, it is possible to create new embodiments by combining the components described in the above embodiments.

[0059] The embodiments described above are for illustrative purposes only and may be modified, replaced, added, or omitted within the scope of the claims or equivalents.

[0060] (Note) The above description of embodiments discloses the following technology.

[0061] (Technology 1) A fuel cell system comprising: a plurality of fuel cell units; and an operation control device that controls the power generated by the plurality of fuel cell units based on an operation plan, wherein each of the plurality of fuel cell units is equipped with a control unit that controls the operation of the fuel cell unit, and the control unit operates the fuel cell unit in a low-power mode during trial operation, and the power generated by the fuel cell unit in the low-power mode is less than the minimum power generated during normal operation of the fuel cell unit.

[0062] According to the fuel cell system of Technology 1, even if the fuel cell system includes multiple fuel cell units undergoing trial operation, the trial operation can be maintained while ensuring that the planned power generation limit is not exceeded. In other words, even if a fuel cell unit undergoing trial operation is included, the output of the fuel cell system can be kept within the planned power generation limit according to the operation plan. This prevents unplanned shutdowns of other fuel cell units during normal operation due to the power generated by the trial operation of a fuel cell unit exceeding the planned power generation limit of the fuel cell system. As a result, the number of starts and stops can be reduced, and the deterioration of the fuel cell units can be suppressed.

[0063] In fuel cell systems, it is possible to sell surplus electricity back to the power company through reverse power flow by contracting with the power company. However, when such a contract does not exist with the power company, the technology of this disclosure is particularly useful for commissioning a fuel cell unit while keeping the generated power within the allowable range planned by the operating plan.

[0064] (Technology 2) The fuel cell system according to Technology 1, wherein the control unit operates the fuel cell unit in the low-power mode, generating power within a range that does not exceed the power required to operate the fuel cell unit, and not outputting power to the outside from the fuel cell unit.

[0065] According to the fuel cell system of Technology 2, even when a fuel cell unit is under commissioning, the output of the fuel cell system can be more reliably kept within the allowable range of power generation planned by the operating plan.

[0066] (Technology 3) The fuel cell system further comprises: an energy storage device for storing electricity generated by the plurality of fuel cell units; and a detector for detecting the amount of energy stored in the energy storage device, wherein when the fuel cell unit is operating in the low-power mode, if the amount of energy stored in the energy storage device is less than a predetermined value, the electricity generated by the fuel cell unit in the low-power mode is stored in the energy storage device, as described in Technology 1 or 2.

[0067] According to the fuel cell system of Technology 3, even when a fuel cell unit is under trial operation and under severe conditions such as a very small allowable range for power generation in the operation plan, the output of the fuel cell system can be kept within the allowable range of power generation planned by the operation plan.

[0068] (Technical 4) The fuel cell system according to Technical 3, wherein when the fuel cell unit is operating in the low-power mode, if the amount of energy stored in the energy storage device is greater than or equal to a predetermined value, the control unit operates the fuel cell unit so as not to exceed the power required to operate the fuel cell unit, and so as not to output power to the outside from the fuel cell unit.

[0069] According to the fuel cell system of Technology 4, even during trial operation when the energy storage device cannot store energy, the power generation does not exceed the planned power generation power set by the operation control device, and trial operation can be performed while maintaining the plan.

[0070] (Technical 5) When the fuel cell unit is in trial operation and receives a power request from the operation control device, the control unit operates the fuel cell unit to cancel the low power mode and output power based on the power request, according to any one of Technical 1 to 4.

[0071] According to the fuel cell system of Technology 5, even if other fuel cell units unexpectedly shut down due to errors or other reasons during trial operation, the power output will not fall short of the power generation power planned in the operation plan, and the operation plan can be maintained.

[0072] (Technical 6) The fuel cell system according to any one of Technical 1 to 5, wherein the control unit notifies the operation control device that the trial run of the fuel cell unit has been completed.

[0073] According to the fuel cell system of Technology 6, the operation control system can incorporate the fuel cell unit, which has completed trial operation and is capable of generating power normally, into the operation plan.

[0074] (Technical 7) A method for operating a fuel cell system comprising a plurality of fuel cell units, the method comprising: (I) controlling the power generated by the plurality of fuel cell units based on an operation plan; and (II) if the plurality of fuel cell units include a fuel cell unit undergoing trial operation, operating the fuel cell unit undergoing trial operation in a low-power mode in which the power generated is less than the minimum power generated during normal operation of the fuel cell unit.

[0075] According to the operating method of Technology 7, even if the fuel cell system includes multiple fuel cell units undergoing trial operation, the trial operation can be performed while maintaining the operating plan so as not to exceed the upper limit of the planned allowable range of power generation. In other words, even if a fuel cell unit undergoing trial operation is included, the output of the fuel cell system can be kept within the allowable range of power generation planned by the operating plan. This prevents unplanned shutdowns of other fuel cell units during normal operation due to the power generated by the trial operation of a fuel cell unit causing the fuel cell system output to exceed the upper limit of the planned allowable range of power generation. As a result, the number of starts and stops can be reduced, and the deterioration of fuel cell units can be suppressed.

[0076] (Technical 8) The method for operating the fuel cell system according to Technical 7, wherein, in (II) above, the fuel cell unit operating in the low-power mode is operated such that the generated power does not exceed the power required to operate the fuel cell unit, and the generated power is not output to the outside from the fuel cell unit.

[0077] According to the operating method of Technology 8, even when a fuel cell unit is under trial operation, the output of the fuel cell system can be more reliably kept within the allowable range of power generation planned by the operating plan.

[0078] (Technical 9) The operating method of a fuel cell system according to Technical 7 or 8, further comprising: (III) storing the power generated by the plurality of fuel cell units in a power storage device, wherein in (II), if the amount of power stored in the power storage device is less than a predetermined value, the power generated by the fuel cell unit operating in the low-power mode is stored in the power storage device.

[0079] According to the operating method of Technology 9, even when a fuel cell unit undergoing trial operation is included, and under severe conditions such as a very small allowable range for power generation in the operating plan, the output of the fuel cell system can be kept within the allowable range of power generation planned by the operating plan.

[0080] (Technical 10) In the above (II), when the amount of energy stored in the energy storage device is greater than or equal to a predetermined value, the fuel cell unit operating in the low-power mode is operated such that the generated power does not exceed the power required to operate the fuel cell unit, and the generated power is not output to the outside from the fuel cell unit, the method of operating a fuel cell system according to Technical 9.

[0081] According to the operation method of Technology 10, even during trial operation when the energy storage device cannot store energy, the power generated will not exceed the planned power generated by the operation control device, and trial operation can be performed while maintaining the plan.

[0082] (Technical 11) The method for operating a fuel cell system according to any one of Technical 7 to 10, wherein, in (II) above, when the fuel cell unit is in trial operation and receives a power request, the low power mode is released and the fuel cell unit is operated to output power based on the power request.

[0083] According to the operating method of Technology 11, even if other fuel cell units stop unexpectedly due to errors or other reasons during trial operation, the power output will not be insufficient compared to the power generation planned in the operating plan, and the operating plan can be maintained.

[0084] (Technical 12) The method for operating a fuel cell system according to any one of Technical 7 to 11, wherein, in (II) above, when the trial run of the fuel cell unit is completed, the operation control device that controls the power generated by the plurality of fuel cell units is notified that the trial run has been completed.

[0085] According to the operating method of Technology 12, the operation control device can incorporate the fuel cell unit, which has completed trial operation and is now capable of generating power normally, into the operation plan.

[0086] The technology described herein is useful for fuel cell systems that include multiple fuel cells, and in which the power generated by these multiple fuel cell units is controlled based on an operating plan.

Claims

1. A fuel cell system comprising: a plurality of fuel cell units; and an operation control device that controls the power generated by the plurality of fuel cell units based on an operation plan, wherein each of the plurality of fuel cell units is equipped with a control unit that controls the operation of the fuel cell unit, and the control unit operates the fuel cell unit in a low-power mode during trial operation, and the power generated by the fuel cell unit in the low-power mode is less than the minimum power generated during normal operation of the fuel cell unit.

2. The fuel cell system according to claim 1, wherein the control unit operates the fuel cell unit in the low-power mode, generating power within a range that does not exceed the power required to operate the fuel cell unit, and not outputting power to the outside from the fuel cell unit.

3. The fuel cell system further comprises: a power storage device for storing electricity generated by the plurality of fuel cell units; and a detector for detecting the amount of electricity stored in the power storage device, wherein when the fuel cell unit is operating in the low-power mode, if the amount of electricity stored in the power storage device is less than a predetermined value, the electricity generated by the fuel cell unit in the low-power mode is stored in the power storage device, as described in claim 1.

4. When the fuel cell unit is operating in the low-power mode, if the amount of energy stored in the energy storage device is greater than or equal to a predetermined value, the control unit operates the fuel cell unit such that it generates power not exceeding the power required to operate the fuel cell unit, and does not output power to the outside from the fuel cell unit, as described in claim 3.

5. The fuel cell system according to claim 1, wherein when the fuel cell unit is in trial operation and receives a power request from the operation control device, the control unit operates the fuel cell unit to release the low power mode and output power based on the power request.

6. The fuel cell system according to claim 1, wherein the control unit notifies the operation control device that the trial run of the fuel cell unit has been completed.

7. A method for operating a fuel cell system comprising a plurality of fuel cell units, the method comprising: (I) controlling the power generated by the plurality of fuel cell units based on an operation plan; and (II) if the plurality of fuel cell units include a fuel cell unit undergoing trial operation, operating the trial fuel cell unit in a low-power mode in which the power generated is less than the minimum power generated during normal operation of the fuel cell unit.

8. The method for operating a fuel cell system according to claim 7, wherein, in (II) above, the fuel cell unit operating in the low-power mode is operated such that the generated power does not exceed the power required to operate the fuel cell unit, and the generated power is not output from the fuel cell unit to the outside.

9. The operating method of a fuel cell system according to claim 7, further comprising: (III) storing the power generated by the plurality of fuel cell units in a power storage device, wherein in (II), if the amount of power stored in the power storage device is less than a predetermined value, the power generated by the fuel cell unit operating in the low-power mode is stored in the power storage device.

10. In the above (II), if the amount of energy stored in the energy storage device is greater than or equal to a predetermined value, the fuel cell unit operating in the low-power mode is operated such that the generated power does not exceed the power required to operate the fuel cell unit, and the generated power is not output to the outside from the fuel cell unit, the method for operating a fuel cell system according to claim 9.

11. The method for operating a fuel cell system according to claim 7, wherein, in (II) above, when the fuel cell unit is in trial operation and receives a power request, the low power mode is released and the fuel cell unit is operated to output power based on the power request.

12. The method for operating a fuel cell system according to claim 7, wherein, in (II) above, when the trial run of the fuel cell unit is completed, the operation control device that controls the power generated by the plurality of fuel cell units is notified that the trial run has been completed.

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