Power generation system and power generation method

Abstract

This suppresses fluctuations in the overall power output of the system when stopping a specific fuel cell and starting other fuel cells. [Solution] The power generation system 1a comprises a first fuel cell 10a, a second fuel cell 10b, and a controller 20. The controller 20 controls the first fuel cell 10a and the second fuel cell 10b. The controller 20 decreases the power generated by the first fuel cell 10a and increases the power generated by the second fuel cell 10b during a specific period E. The controller 20 maintains the sum of the power generated by the first fuel cell 10a and the power generated by the second fuel cell 10b within a predetermined range during the specific period E. The controller 20 stops the first fuel cell 10a after the specific period E has elapsed.

Description

[Technical Field]

[0001] This disclosure relates to a power generation system and a power generation method. [Background technology]

[0002] Patent Document 1 describes a fuel cell system comprising multiple fuel cells and a controller for controlling the multiple fuel cells. The controller determines multiple operating schedules for the multiple fuel cells based on the required power. Each of the multiple fuel cells belongs to one of several groups, which represent a unit of collection of multiple fuel cells operated on different operating schedules. Multiple operating schedules are determined so that the idle periods of multiple fuel cells belonging to the same group do not overlap. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-106797 [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventional technology deserves reconsideration from the perspective of suppressing fluctuations in the overall power generation of the system when stopping a specific fuel cell and starting other fuel cells. [Means for solving the problem]

[0005] The power generation system in this disclosure is First fuel cell and Second fuel cell and The system comprises a controller for controlling the first fuel cell and the second fuel cell, The controller decreases the power generation power of the first fuel cell during a specific period and increases the power generation power of the second fuel cell during the specific period to keep the sum of the power generation power of the first fuel cell and the power generation power of the second fuel cell within a predetermined range during the specific period, and stops the first fuel cell after the elapse of the specific period.

[0006] In another aspect, the power generation method in the present disclosure includes decreasing the power generation power of the first fuel cell during a specific period, increasing the power generation power of the second fuel cell during the specific period to keep the sum of the power generation power of the first fuel cell and the power generation power of the second fuel cell within a predetermined range during the specific period, and stopping the first fuel cell after the elapse of the specific period.

Advantages of the Invention

[0007] According to the present disclosure, fluctuations in the power generation power of the entire system can be suppressed when a specific fuel cell is stopped and another fuel cell is started.

Brief Description of the Drawings

[0008] [Figure 1] Configuration diagram of the power generation system in Embodiment 1 [Figure 2] Flowchart showing the control of the fuel cell of the power generation system in Embodiment 1 [Figure 3A] Graph showing the relationship between the power generation power of the fuel cell of the power generation system in Embodiment 1 and time [Figure 3B] Graph showing the relationship between the power generation power of the fuel cell of the power generation system according to the reference example and time [Figure 4] Configuration diagram of the power generation system in Embodiment 2 [Figure 5] Flowchart showing the control of the fuel cell of the power generation system in Embodiment 2

[0009] (Findings etc. on which the present disclosure is based) At the time the inventors conceived this disclosure, it was known that if a fuel cell is operated continuously for a long period of time, components other than hydrogen accumulate in the cathode of the fuel cell, causing the cathode to become contaminated. When the cathode becomes contaminated, the output voltage of the fuel cell may decrease. Therefore, it is necessary to shut down a fuel cell that has been operated continuously for a predetermined time for a predetermined period of time to allow the cathode to become contaminated.

[0010] Electricity demand varies depending on the user. For example, by combining multiple fuel cells with small power generation capacities, it is possible to construct a power generation system that can meet various electricity demands while keeping development costs down. For example, load fluctuations can be accommodated by adjusting the number of fuel cells in operation. In addition, in order to suppress the decrease in the output power of the power generation system, it is necessary to avoid as much as possible overlapping the shutdown periods of one fuel cell with those of other fuel cells.

[0011] However, in conventional power generation systems equipped with multiple fuel cells, the overall power output of the system could fluctuate after a specific fuel cell was shut down. In conventional power generation systems, a fuel cell, for example, starts generating power at its initial output after a predetermined time has elapsed since receiving a start command, and then increases its output to reach the target output after that initial output is maintained for a predetermined time. On the other hand, in conventional power generation systems, a fuel cell shuts down immediately when a stop command is received. Therefore, in conventional power generation systems, the overall power output of the power generation system could be lower than the overall power output of the power generation system before the shutdown of the specific fuel cell during the period between the shutdown of a specific fuel cell and the start of power generation at the target output of the other fuel cells.

[0012] The inventors focused on adjusting the power generated when a particular fuel cell is shut down to a predetermined relationship with the power generated when other fuel cells are started up, and this has become the subject matter of this disclosure.

[0013] This disclosure provides a power generation system and method that can suppress fluctuations in the overall power generation of the system when stopping a specific fuel cell and starting other fuel cells.

[0014] 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.

[0015] The attached drawings and the following description are provided to enable the parties to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0016] (Embodiment 1) Embodiment 1 will be described below with reference to Figures 1 to 3B.

[0017] [1-1. Structure] Figure 1 is a diagram of the configuration of the power generation system 1a in Embodiment 1. As shown in Figure 1, the power generation system 1a comprises a first fuel cell 10a, a second fuel cell 10b, and a controller 20. The controller 20 controls the first fuel cell 10a and the second fuel cell 10b. The power generation system 1a further comprises a hydrogen-containing gas supply path 31, an oxygen-containing gas supply path 32, and a power line 15. The first fuel cell 10a and the second fuel cell 10b are connected in parallel to an external load 40 of the power generation system 1a, for example, via the power line 15. The load 40 is a power load that consumes electricity.

[0018] Each of the first fuel cell 10a and the second fuel cell 10b comprises an electrolyte membrane 11, an anode 12, and a cathode 13. The electrolyte membrane 11 is positioned between the anode 12 and the cathode 13. Both the anode 12 and the cathode 13 are provided with a catalyst to promote the electron extraction reaction. A hydrogen-containing gas supply path 31 is connected to the anode 12. An oxygen-containing gas supply path 32 is connected to the cathode 13. Hydrogen-containing gas is supplied to the anode 12 from a hydrogen-containing gas supply source 41 through the hydrogen-containing gas supply path 31. Oxygen-containing gas is supplied to the cathode 13 from an oxygen-containing gas supply source 42 through the oxygen-containing gas supply path 32.

[0019] The power generation system 1a may include three or more fuel cells, including a first fuel cell 10a and a second fuel cell 10b. The number of fuel cells in the power generation system 1a is not limited to a specific value. The power generation system 1a may include five or more, ten or more, twenty or more, fifty or more, and one hundred or more fuel cells. The number of fuel cells in the power generation system 1a is determined according to the required output power of the power generation system 1a.

[0020] The fuel cells included in power generation system 1a, for example, have identical configurations. If a single fuel cell has a rated output power of 5kW and power generation system 1a includes 10 fuel cells, power generation system 1a can produce a maximum output power of 50kW. On the other hand, considering factors such as the need to shut down the fuel cells to clear cathode contamination, the maximum output power of power generation system 1a may be less than 50kW when it includes 10 fuel cells.

[0021] The hydrogen-containing gas may be pure hydrogen gas or gas obtained by steam reforming. Examples of hydrogen-containing gas supply sources 41 include hydrogen storage tanks, other hydrogen gas infrastructure, and reformers. The oxygen-containing gas is, for example, air. An example of oxygen-containing gas supply source 42 is an air blower. Other equipment (not shown), such as flow control valves, is arranged in the hydrogen-containing gas supply path 31 and the oxygen-containing gas supply path 32.

[0022] Each of the first fuel cell 10a and the second fuel cell 10b is, for example, a polymer electrolyte fuel cell (PEFC). Since the continuous operation time of a PEFC is relatively short, applying the technology of this disclosure to a system using a PEFC will yield better results. Each of the first fuel cell 10a and the second fuel cell 10b may be another type of fuel cell, such as a solid oxide fuel cell (SOFC).

[0023] The controller 20 controls the operation and shutdown of the first fuel cell 10a and the second fuel cell 10b. The controller 20 controls the first fuel cell 10a and the second fuel cell 10b according to their respective operating schedules. According to the operating schedule, when the first fuel cell 10a stops, the second fuel cell 10b starts up. The controller 20 is a DSP (Digital Signal Processor) that includes, for example, an arithmetic circuit and a memory circuit. An example of an arithmetic circuit is a CPU. An example of a memory circuit is a memory. The control program for the power generation system 1a is stored in the memory circuit.

[0024] [1-2. Operation] The operation and function of the power generation system 1a, configured as described above, will be explained below.

[0025] Figure 2 is a flowchart showing the control of the fuel cell in the power generation system in Embodiment 1. At the start of the control shown in Figure 2, the first fuel cell 10a is generating power with an output of P1 [W], and the second fuel cell 10b is stopped.

[0026] In step S1, it is determined whether the operating time t1 of the first fuel cell 10a since its most recent startup exceeds a predetermined time Tr. The predetermined time Tr is, for example, between 50 and 200 hours.

[0027] If the operation time t1 since the most recent startup of the first fuel cell 10a exceeds a predetermined time Tr, there is a high possibility that components other than hydrogen accumulate on the cathode 12 of the first fuel cell 10a and the cathode 12 is contaminated. Therefore, it is necessary to stop the first fuel cell 10a to put it on standby in order to eliminate the contamination of the cathode 12. For example, by putting the first fuel cell 10a on standby for 2 hours or more, the contamination of the cathode 12 is eliminated and the first fuel cell 10a becomes operable. Therefore, if the determination in step S1 is affirmative, the process proceeds to step S2, and the controller 20 sends a control signal instructing the stop of the first fuel cell 10a. In addition, a control signal instructing the startup of the second fuel cell 10b in standby is sent.

[0028] FIG. 3A is a graph showing the relationship between the power generation power of the fuel cell of the power generation system 1a and time. In FIG. 3A, at time T0, a control signal instructing the stop of the first fuel cell 10a and a control signal instructing the startup of the second fuel cell 10b are sent. In FIG. 3A, the solid line graph indicates the target value of the power generation power W

[0029] of the first fuel cell 10a, and the broken line graph indicates the target value of the power generation power W b of the second fuel cell 10b.

[0029] As shown in FIG. 3A, in a specific period E from time T1 to time T3, the controller 20 decreases the power generation power of the first fuel cell 10a to stop the power generation of the first fuel cell 10a. In addition, the power generation power of the second fuel cell 10b is increased in the specific period E. In the specific period E, the process shown in step S3 is executed, and the controller 20 controls the power generation power W a of the first fuel cell 10a and the power generation power W b of the second fuel cell 10b so that the sum (W a +W b ) is adjusted within a predetermined range. For example, the controller 20 controls the first fuel cell 10a and the second fuel cell 10b so that the power generation power W a and the power generation power W b become the target values shown in FIG. 3A. Thereby, for example, the sum (W a +W b ) satisfies 0.95×P1≦(Wa +W b The first fuel cell 10a and the second fuel cell 10b are controlled to satisfy the condition ) ≤ 1.05 × P1. Therefore, the sum (W a +W b ) will be the same as, or close to, the output P1 of the first fuel cell 10a immediately before the first fuel cell 10a is instructed to shut down.

[0030] The length of the specific period E is, for example, between 0.5 minutes and 10 minutes.

[0031] As shown in Figure 3A, the controller 20 controls the power generated by the first fuel cell 10a W during a specific period E. a The power is reduced in stages or continuously. In addition, the controller 20 controls the power W generated by the second fuel cell 10b during a specific period E. b The power is increased in stages or continuously. For example, the generated power W at time T1. b The initial output P0[W] is gradually increased, and the generated power W is generated during the period from time T1 to time T2. b The initial output P0 is maintained. Meanwhile, the generated power W a It is adjusted to a value corresponding to P1-P0, and the sum (W a +W b ) is adjusted to a predetermined range. Next, the generated power W during the period from time T2 to time T3 b The power generated increases continuously, b The output P1 approaches the power W. a The power continuously decreases, and at time T3, the generated power W a When the value becomes 0, the first fuel cell 10a stops and enters a shutdown period after the expiration of a specific period E.

[0032] Power generation W a and power generation W bThese can be adjusted by adjusting the flow rate of hydrogen-containing gas supplied to the anode 12 or the flow rate of oxygen-containing gas supplied to the cathode 13 in the first fuel cell 10a and the second fuel cell 10b, respectively. For example, the flow rate of hydrogen-containing gas supplied to the anode 12 can be adjusted by adjusting the opening of the flow control valve provided in the hydrogen-containing gas supply source 41 and the hydrogen-containing gas supply path 31 or by adjusting the output of the pump for supplying the hydrogen-containing gas. In addition, the flow rate of oxygen-containing gas supplied to the cathode 13 can be adjusted by adjusting the output of the air blower, which is the oxygen-containing gas supply source 42. In the first fuel cell 10a, if the flow rate of hydrogen-containing gas supplied to the anode 12, the flow rate of oxygen-containing gas supplied to the cathode 13, or both decreases, the generated power W a The power generated W decreases. In the second fuel cell 10b, when the flow rate of hydrogen-containing gas supplied to the anode 12, the flow rate of oxygen-containing gas supplied to the cathode 13, or both, increases, the power generated W decreases. b It increases.

[0033] During a specific period E, the generated power W b When the second fuel cell 10b is started up so that the power generated W increases as shown in Figure 3A, b From a stable state with initial output P0, the generated power W b The output gradually approaches the target output P1. This tends to increase the reliability of the auxiliary equipment, and consequently, the reliability of the power generation system 1a.

[0034] Figure 3B is a graph showing the relationship between the power generated by the fuel cell of the power generation system according to the reference example and time. The power generation system according to the reference example is configured the same as power generation system 1a, except for the parts that are specifically explained. In Figure 3B, at time T0, as soon as a control signal is sent to instruct the first fuel cell 10a to stop, the first fuel cell 10a stops, and the power generated W a It is set to 0. In the power generation system shown in the example, at time T0, a control signal is sent to instruct the second fuel cell 10b to start. However, the generated power W bThe output is increased stepwise to the initial output P0 at time T1, maintained at the initial output P0 from time T1 to time T2, and continuously increases from time T2 to time T3, approaching the target output P1. Therefore, during the period from time T0 to time T3, the total power generated by the power generation system in the reference example can fluctuate significantly from the output P1 immediately before the shutdown of the first fuel cell 10a. On the other hand, according to power generation system 1a, in a specific period E, the sum (W a +W b The value is adjusted to a predetermined range. As a result, when the first fuel cell 10a is stopped and the second fuel cell 10b is started in the power generation system 1a, fluctuations in the power generated by the entire power generation system 1a are easily suppressed.

[0035] In step S4, the generated power W b When it is determined that the target output P1 has been reached, the controller 20 terminates the series of processes.

[0036] (Embodiment 2) Embodiment 2 will be described below with reference to Figures 4 and 5.

[0037] [2-1. Structure] Figure 4 is a diagram showing the configuration of power generation system 1b in Embodiment 2. Power generation system 1b is configured similarly to power generation system 1a, except for parts that are not specifically described. Components of power generation system 1b that are the same as or correspond to components of power generation system 1a are denoted by the same reference numerals, and detailed descriptions are omitted. Descriptions of power generation system 1a also apply to power generation system 1b, to the extent that they do not contradict the technical description.

[0038] As shown in Figure 4, the power generation system 1b is equipped with a first power meter 14a. The first power meter 14a measures the power generated by the first fuel cell 10a W a The second power meter 14b detects the power generated by the second fuel cell 10b W. b The generated power W is detected by the first wattmeter 14a and the second wattmeter 14b. a and power generation W b This is input to the controller 20.

[0039] [2-2. Operation] The operation and function of the power generation system 1b, configured as described above, will be explained below.

[0040] Figure 5 is a flowchart showing the control of the fuel cell in power generation system 1b. In power generation system 1b, similar to power generation system 1a, the process shown in step S3 is executed during a specific period E, and the controller 20 controls the power generated by the first fuel cell 10a W. a and the power generated by the second fuel cell 10b W b The sum of (W a +W b ) adjusts to a predetermined range. In the power generation system 1b, the controller 20 further adjusts the generated power W in step S31. a and power generation W b The detection data is obtained from the first power meter 14a and the second power meter 14b, respectively.

[0041] Next, in step S32, the controller 20 receives the generated power W from the first power meter 14a. b Power generation W a Adjust the power generation W at a certain point in a specific period E due to the effects of external disturbances, etc. b Detected value and the power generated at that time (W) b It is anticipated that the difference from the initial target value will become large. In this case, the generated power W at that point in time will be... a Regardless of the initial target value, the sum (W a +W b The generated power W ) falls within a predetermined range. a The power generated during the startup of a fuel cell tends to be unstable. On the other hand, it is relatively easy to adjust the power generated by a fuel cell that is already in operation.

[0042] (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.

[0043] Since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or equivalents thereof.

[0044] In Embodiment 1, when the operating time t1 of the first fuel cell 10a since the most recent startup exceeds a predetermined time Tr, the system transitions to a specific period E and processes steps S2 to S4. In other words, the controller 20 may perform steps S2 to S4 when the first fuel cell 10a has generated power continuously for a predetermined time, or when another condition is met after the first fuel cell 10a has generated power continuously for a predetermined time. In addition, for example, steps S2 to S4 may be performed when a condition is met that requires the first fuel cell 10a to be stopped.

[0045] The power generation systems 1a and 1b may be used in conjunction with a photovoltaic power generation device, or in conjunction with a photovoltaic power generation device and a storage battery.

[0046] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0047] (Technology 1) First fuel cell and Second fuel cell and The system comprises a controller for controlling the first fuel cell and the second fuel cell, The controller reduces the power generated by the first fuel cell during a specific period and increases the power generated by the second fuel cell during the same period to maintain the sum of the power generated by the first fuel cell and the power generated by the second fuel cell within a predetermined range during the specified period, and then shuts down the first fuel cell after the specified period has elapsed. Power generation system.

[0048] According to the power generation system of Technology 1, during a specific period, the sum of the power generated by the first fuel cell and the power generated by the second fuel cell is kept within a predetermined range, while the power generated by the first fuel cell decreases and the power generated by the second fuel cell increases. Therefore, when the first fuel cell is stopped and the second fuel cell is started, fluctuations in the overall power generation of the system can be suppressed.

[0049] (Technology 2) The controller, during the specified period, gradually or continuously reduces the power generated by the first fuel cell and gradually or continuously increases the power generated by the second fuel cell. The power generation system described in Technology 1.

[0050] According to the power generation system of Technology 2, the power generated by the second fuel cell increases in stages or continuously, which enhances the reliability of the power generation system and tends to extend its lifespan.

[0051] (Technology 3) The controller transitions to the specified period on the condition that the first fuel cell has continuously generated power for a predetermined period of time. A power generation system as described in Technology 1 or 2.

[0052] According to the power generation system of Technology 3, when the first fuel cell is shut down to eliminate cathode contamination associated with the continuous operation of the first fuel cell, fluctuations in the overall power generation of the system can be suppressed.

[0053] (Technology 4) The controller adjusts the power generated by the first fuel cell to match the power generated by the second fuel cell during the specified period. A power generation system described in any one of the three technical specifications (1 to 3).

[0054] According to the power generation system of Technology 4, even if the power generated by the second fuel cell deviates from the target value due to external disturbances, fluctuations in the overall power generation of the system are easily suppressed.

[0055] (Technology 5) To reduce the power generation of the first fuel cell for a specific period, The power generated by the second fuel cell is increased during the specified period to maintain the sum of the power generated by the first fuel cell and the power generated by the second fuel cell within a predetermined range during the specified period. This includes shutting down the first fuel cell after the specified period has elapsed, Method of generating electricity.

[0056] According to power generation technology 5, when the fuel cell of the first fuel cell is stopped and the fuel cell of the second fuel cell is started, fluctuations in the overall power generation of the system can be suppressed. [Industrial applicability]

[0057] The technology disclosed herein is applicable to power generation systems equipped with multiple fuel cells, and can be applied to power generation systems that supply electricity by linking solar power generation facilities, fuel cell facilities, battery storage facilities, and commercial power sources. The technology disclosed herein is also applicable to environmental protection initiatives such as RE100 (Renewable Energy 100%). [Explanation of Symbols]

[0058] 1a, 1b Power generation system 10a Daiichi Fuel Cell 10b Second fuel cell 20 Controllers E. Specific period

Claims

1. First fuel cell and Second fuel cell and The system comprises a controller for controlling the first fuel cell and the second fuel cell, The controller reduces the power generated by the first fuel cell during a specific period and increases the power generated by the second fuel cell during the same period to maintain the sum of the power generated by the first fuel cell and the power generated by the second fuel cell within a predetermined range during the specified period, and then shuts down the first fuel cell after the specified period has elapsed. Power generation system.

2. The controller, during the specified period, gradually or continuously reduces the power generated by the first fuel cell and gradually or continuously increases the power generated by the second fuel cell. The power generation system according to claim 1.

3. The controller transitions to the specified period on the condition that the first fuel cell has continuously generated power for a predetermined period of time. The power generation system according to claim 1.

4. The controller adjusts the power generated by the first fuel cell to match the power generated by the second fuel cell during the specified period. The power generation system according to claim 1.

5. To reduce the power generation of the first fuel cell for a specific period, The power generated by the second fuel cell is increased during the specified period to maintain the sum of the power generated by the first fuel cell and the power generated by the second fuel cell within a predetermined range during the specified period. This includes shutting down the first fuel cell after the specified period has elapsed, Method of generating electricity.

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