Method for controlling fuel cell device, control device, and fuel cell system

Abstract

A method for controlling a fuel cell device according to the present disclosure comprises: receiving a voltage that is measured at a time of electric power generation of the fuel cell device; and determining whether the state of degradation of the fuel cell device is normal, on the basis of the voltage and, among first threshold values that decrease as the operation amount of the fuel cell device increases, a first threshold value that corresponds to the operation amount of the fuel cell device at the time the voltage was measured.

Description

Fuel cell device control method, control device, and fuel cell system

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

[0002] Various proposals have been made regarding the deterioration determination of fuel cell devices. For example, Patent Document 1 discloses a solid oxide fuel cell comprising a fuel cell module including a plurality of solid oxide fuel cells and a reformer, a fuel supply means for supplying fuel to the reformer, an oxidant gas supply means for supplying oxidant gas to the plurality of solid oxide fuel cells, a water supply means for supplying water to the reformer, and a control means for varying the amount of fuel supplied from the fuel supply means in accordance with a required amount of power generation, the control means including a deterioration determination means for determining deterioration of the fuel cell module, the deterioration determination means continuing operation at fixed values ​​in which predetermined constant supply amounts of fuel, oxidant gas, and water are supplied from the fuel supply means, the oxidant gas supply means, and the water supply means, respectively, until the fuel cell module reaches a stable operating state, and then performing a deterioration determination.

[0003] Japanese Patent Application Laid-Open No. 2010-238617

[0004] An object of the present disclosure is to provide, as an example, a control method for a fuel cell device, a control device, and a fuel cell system that can monitor the degradation state of a fuel cell device more appropriately than conventional methods.

[0005] In order to solve the above problem, a control method for a fuel cell device according to one aspect of the present disclosure receives a voltage measured when the fuel cell device is generating electricity, and determines whether the deterioration state of the fuel cell device is normal based on a comparison between the voltage and a first threshold value that decreases as the operating amount of the fuel cell device increases, the first threshold value corresponding to the operating amount of the fuel cell device at the time the voltage was measured.

[0006] In addition, a control device according to one aspect of the present disclosure includes a receiver that receives a voltage measured when the fuel cell device is generating electricity, and a controller that determines whether the deterioration state of the fuel cell device is normal or not based on a comparison between the voltage and a first threshold value that decreases as the operating amount of the fuel cell device increases, the first threshold value corresponding to the operating amount of the fuel cell device at the time the voltage is measured.

[0007] A fuel cell system according to an aspect of the present disclosure includes a fuel cell device and the above-described control device.

[0008] The control method, control device, and fuel cell system of one aspect of the present disclosure have the advantage of being able to monitor the degradation state of the fuel cell device more appropriately than ever before.

[0009] FIG. 1 is a diagram illustrating an example of a fuel cell system according to an embodiment. FIG. 2 is a diagram illustrating an example of a control device of FIG. 1. FIG. 3 is a diagram illustrating an example of voltage stabilization timing when a predetermined time has elapsed since the start of power generation by the fuel cell device and the voltage stabilizes. FIG. 4 is a flowchart illustrating an example of operation of a control device in a fuel cell system according to an embodiment (a control method for a fuel cell device). FIG. 5 is a flowchart illustrating an example of a method for creating a first threshold value for determining whether the degradation state of the fuel cell device is normal and a second threshold value for determining whether to continue power generation by the fuel cell device when the voltage falls below a predicted state of voltage drop due to degradation of the fuel cell device. FIG. 6 is a diagram illustrating an example of a first threshold value for determining whether the degradation state of the fuel cell device is normal and a second threshold value for determining whether to continue power generation by the fuel cell device when the voltage falls below a predicted state of voltage drop due to degradation of the fuel cell device. FIG. 7 is a flowchart illustrating an example of operation of a fuel cell device in a fuel cell system according to a first example of an embodiment (a control method for a fuel cell device).

[0010] Patent Document 1 describes the determination of deterioration of a fuel cell module, but it only determines whether or not the module is deteriorated, and does not determine whether or not the deteriorated state is normal if it is deteriorated.

[0011] Therefore, the control method for a fuel cell device of the first aspect of the present disclosure receives the voltage measured when the fuel cell device is generating electricity, and determines whether the deterioration state of the fuel cell device is normal based on a comparison between the voltage and a first threshold value that decreases as the operating amount of the fuel cell device increases, the first threshold value corresponding to the operating amount of the fuel cell device at the time the voltage was measured.

[0012] According to the above, the control method of the fuel cell device of this aspect can monitor the deterioration state of the fuel cell device more appropriately than ever before.

[0013] Specifically, the control method of the fuel cell device of this aspect can appropriately monitor whether the degradation state of the fuel cell device is normal or not in the range where the voltage falls below the predicted state of voltage drop due to degradation of the fuel cell device, compared to when the above-mentioned first threshold value for determining whether the degradation state of the fuel cell device is normal or not is not taken into account.

[0014] A second aspect of the present disclosure is a control method for a fuel cell device, which may be the first aspect of the control method for a fuel cell device, such that when the voltage is equal to or greater than a first threshold, the degradation state of the fuel cell device is determined to be normal, when the voltage is less than the first threshold and equal to or greater than a second threshold that is less than the first threshold, the degradation state of the fuel cell device is determined to be abnormal and power generation by the fuel cell device is continued, and when the voltage is less than the second threshold, power generation by the fuel cell device is stopped.

[0015] According to the above, the control method for a fuel cell device of this embodiment can determine that the deterioration state of the fuel cell device is abnormal while continuing to generate power when the voltage measured during power generation of the fuel cell device is less than the first threshold value and greater than or equal to the second threshold value within a range where the voltage has fallen below the predicted state of voltage drop due to deterioration of the fuel cell device.

[0016] Furthermore, the control method of the fuel cell device of this aspect can stop power generation of the fuel cell device when the voltage measured during power generation of the fuel cell device is less than a second threshold value, thereby allowing the fuel cell device to be repaired or replaced in a timely manner.

[0017] A third aspect of the present disclosure is a control method for a fuel cell device, wherein in the control method for a fuel cell device of the second aspect, a first threshold value corresponding to the operating amount of the fuel cell device when the operating amount is a value that is determined to be the end of the life of the fuel cell device may be equal to or greater than the second threshold value.

[0018] As described above, the first threshold decreases as the operating amount of the fuel cell device increases, and therefore, in the control method for a fuel cell device of this embodiment, the magnitude relationship between the first threshold and the second threshold is as described above, and both can be appropriately set so that the first threshold does not become less than the second threshold throughout the entire period until the operating amount of the fuel cell device is determined to be the end of the life of the fuel cell device.

[0019] A fourth aspect of the present disclosure relates to a control method for a fuel cell device according to the second or third aspect, wherein the second threshold value may be constant regardless of the operating amount of the fuel cell device.

[0020] A fifth aspect of the control method for a fuel cell device of the present disclosure may be such that, in any one of the second to fourth aspects of the control method for a fuel cell device, when the voltage measured during power generation by the fuel cell device is less than a first threshold value and greater than or equal to a second threshold value, the fuel cell device is caused to generate power under the same operating conditions as when the voltage is greater than or equal to the first threshold value.

[0021] According to the above, in the control method of the fuel cell device of this embodiment, even if the voltage measured during power generation of the fuel cell device is less than the first threshold and greater than or equal to the second threshold, power generation of the fuel cell device is performed under conditions maintaining the operating conditions when the voltage is greater than or equal to the first threshold, thereby suppressing output fluctuations of the fuel cell device compared to when the fuel cell device is generated under operating conditions different from the operating conditions when the voltage is greater than or equal to the first threshold.

[0022] A sixth aspect of the present disclosure is a control method for a fuel cell device, which is a control method for a fuel cell device according to any one of the second to fourth aspects, and which may cause the fuel cell device to generate electricity by setting at least one of the fuel gas utilization rate and the oxidant gas utilization rate to be equal to or higher than when the voltage is equal to or higher than the first threshold value when the voltage is equal to or higher than the first threshold value when the voltage is equal to or higher than the first threshold value.

[0023] According to the above, in the control method of the fuel cell device of this embodiment, even if the voltage measured during power generation of the fuel cell device is less than the first threshold and greater than the second threshold, power generation of the fuel cell device is performed by setting at least one of the gas utilization rates to be equal to or higher than when the voltage is greater than the first threshold, thereby appropriately maintaining or improving the power generation efficiency of the fuel cell device compared to when the gas utilization rate is reduced from when the voltage is greater than the first threshold.

[0024] A seventh aspect of the present disclosure is a control method for a fuel cell device, which may be the first aspect of the control method for a fuel cell device, such that when the voltage measured during power generation by the fuel cell device is equal to or greater than a first threshold, the deterioration state of the fuel cell device is determined to be normal, and when this voltage is less than the first threshold, the deterioration state of the fuel cell device is determined to be abnormal, and power generation by the fuel cell device is continued under the same operating conditions as when the voltage is equal to or greater than the first threshold.

[0025] According to the above, in the control method of the fuel cell device of this aspect, even if the voltage measured during power generation of the fuel cell device is less than the first threshold, power generation of the fuel cell device is performed under conditions maintaining the operating conditions when the voltage is equal to or greater than the first threshold, and therefore output fluctuations of the fuel cell device can be suppressed compared to when the fuel cell device is generated under operating conditions different from the operating conditions when the voltage is equal to or greater than the first threshold.

[0026] The control method for a fuel cell device of an eighth aspect of the present disclosure may be the same as the control method for a fuel cell device of the first aspect, in which when the voltage measured during power generation by the fuel cell device is equal to or greater than a first threshold, the deterioration state of the fuel cell device is determined to be normal, and when this voltage is less than the first threshold, the deterioration state of the fuel cell device is determined to be abnormal, and at least one of the fuel gas utilization rate and the oxidant gas utilization rate may be set to be equal to or higher than when the voltage is equal to or greater than the first threshold, allowing the fuel cell device to continue generating power.

[0027] According to the above, the control method of the fuel cell device of this embodiment generates power in the fuel cell device by setting at least one of the gas utilization rates to be equal to or higher than when the voltage is equal to or higher than when the voltage is equal to or higher than the first threshold, even if the voltage measured during power generation in the fuel cell device is less than the first threshold, thereby making it possible to appropriately maintain or improve the power generation efficiency of the fuel cell device compared to when the gas utilization rate is reduced from when the voltage is equal to or higher than the first threshold.

[0028] A control method for a fuel cell device of a ninth aspect of the present disclosure may, in any one of the control methods for a fuel cell device of the first to fourth aspects, notify an external device of the determination result of whether the deterioration state of the fuel cell device is normal or not.

[0029] A control method for a fuel cell device of a tenth aspect of the present disclosure may be a control method for a fuel cell device of any one of the first to fourth aspects, in which, when the degradation state of the fuel cell device is determined to be abnormal, a prediction of the replacement time of the fuel cell device is revised and the revised replacement time of the fuel cell device is notified to an external device.

[0030] Normally, the predicted value for the time to replace a fuel cell is set to a value corresponding to normal deterioration of the fuel cell device. However, if the voltage measured during power generation falls below the first threshold and the deterioration state of the fuel cell device is determined to be abnormal, this voltage drop is often a sign that the time to replace the fuel cell device will come sooner.

[0031] Therefore, in the control method for a fuel cell device of this embodiment, when the deterioration state of the fuel cell device is determined to be abnormal, the prediction of the replacement time of the fuel cell device is corrected based on the measured voltage that is less than the first threshold value, and this is notified to an external device, thereby obtaining more appropriate information regarding the replacement time of the fuel cell device than if such a prediction of the replacement time is not corrected.

[0032] The control method for a fuel cell device of an eleventh aspect of the present disclosure may be such that, in the control method for a fuel cell device of any one of the first to fourth aspects, when the degradation state of the fuel cell device is determined to be abnormal, a prediction of the maintenance time for the fuel cell device is revised and the revised maintenance time for the fuel cell device is notified to an external device.

[0033] Normally, the predicted value for the timing of fuel cell maintenance is set to a value corresponding to normal deterioration of the fuel cell device. However, if the voltage measured during power generation by the fuel cell device falls below the first threshold and the deterioration state of the fuel cell device is determined to be abnormal, this voltage drop is often a sign that the timing of maintenance of the fuel cell device will come sooner.

[0034] Therefore, in the control method for a fuel cell device of this embodiment, when the deterioration state of the fuel cell device is determined to be abnormal, the prediction of the maintenance time for the fuel cell device is corrected based on the measured voltage that is less than the first threshold value, and this is notified to an external device, thereby obtaining more appropriate information regarding the maintenance time for the fuel cell device than if such a correction of the prediction of the maintenance time is not made.

[0035] The control device of the twelfth aspect of the present disclosure comprises a receiver that receives a voltage measured when the fuel cell device is generating electricity, and a controller that determines whether the deterioration state of the fuel cell device is normal or not based on a comparison between the voltage and a first threshold value that decreases as the operating amount of the fuel cell device increases, the first threshold value corresponding to the operating amount of the fuel cell device at the time the voltage is measured.

[0036] With this configuration, the control device of this aspect can monitor the deterioration state of the fuel cell device more appropriately than before. Note that the details of the effects achieved by the control device of this aspect are the same as the effects achieved by the control method of the fuel cell device of the first aspect, so a detailed explanation will be omitted.

[0037] A fuel cell system according to a thirteenth aspect of the present disclosure includes a fuel cell device and the control device according to the twelfth aspect.

[0038] With this configuration, the fuel cell system of this aspect can monitor the deterioration state of the fuel cell device more appropriately than in the past. Note that the detailed effects of the fuel cell system of this aspect are similar to those of the control method of the first aspect of the fuel cell device, and therefore will not be described here.

[0039] Specific examples of the above-described aspects of the present disclosure will be described below with reference to the accompanying drawings. Each of the specific examples described below is an example of the above-described aspects of the present disclosure. Therefore, unless otherwise stated in the claims, the shapes, numerical values, components, arrangement positions and connection forms of the components shown below do not limit the scope of the claims.

[0040] Furthermore, among the components described below, components that are not described in the independent claims that represent the highest concept of the present disclosure are described as optional components. Furthermore, in the drawings, components with the same reference numerals may not be described in detail. The drawings are schematic illustrations of each component for ease of understanding, and the shapes, dimensional ratios, and the like may not be accurately depicted.

[0041] Furthermore, in the operation of the apparatus, the order of steps may be changed or known steps may be added as necessary.

[0042] (Embodiment) [Device Configuration] Fig. 1 is a diagram showing an example of a fuel cell system according to an embodiment, and Fig. 2 is a diagram showing an example of a control device of Fig. 1 .

[0043] The fuel cell system 10 of this embodiment includes a fuel cell device 15 and a control device 20. Here, the fuel cell system 10 may be configured as a single power generation unit including a fuel cell, or as shown in FIG. 1, it may include multiple power generation units including fuel cells. In this example, the fuel cell system 10 includes a group of power generation units consisting of power generation units a1-an, b1-bn, c1-cn, d1-dn, and e1-en. In this case, the fuel cell system 10 may be, for example, a system that supplies large amounts of power to a power grid. Therefore, the configuration of the group of power generation units in FIG. 1 will be described in more detail below.

[0044] The power generation unit group is made up of multiple power generation units a1 to an, b1 to bn, c1 to cn, d1 to dn, and e1 to en. Although not shown, each of these power generation units a1 to an, b1 to bn, c1 to cn, d1 to dn, and e1 to en is made up of a fuel cell stack, a power conditioner for converting DC power generated by the fuel cell stack into AC power and outputting it to the power grid, and a control device for controlling the operation of these devices.

[0045] In this example, the power generation unit group is divided into power generation units a1 to an belonging to group A, power generation units b1 to bn belonging to group B, power generation units c1 to cn belonging to group C, power generation units d1 to dn belonging to group D, and power generation units e1 to en belonging to group E. All power generation units belonging to one group are also simply referred to as "power generation units in a group." For ease of explanation, hereinafter, power generation units a1 to an, b1 to bn, c1 to cn, d1 to dn, and e1 to en may be abbreviated as "power generation unit 15ij (i = a to e, j = 1 to n)." Note that, in this example, each power generation unit corresponds to a fuel cell power generation device of the present disclosure, but each group may also correspond to a fuel cell power generation device of the present disclosure.

[0046] However, the above configuration of the power generation unit group is merely an example and is not limited to this example. For example, the power generation unit group may be grouped by the power generation units in a single group.

[0047] Control devices 30A to 30E are provided for power generation units a1 to an in group A, power generation units b1 to bn in group B, power generation units c1 to cn in group C, power generation units d1 to dn in group D, and power generation units e1 to en in group E, respectively, and control the operation of each power generation unit within the group.

[0048] For example, the control device 30A controls the output of each of the power generation units a1 to an belonging to group A via a communication network so as to enable efficient operation (for example, optimization of the life span) of the power generation units a1 to an.

[0049] The control devices 30A to 30E may be any device that has a control function and includes an arithmetic processing unit (not shown), a memory unit (not shown) that stores a control program, and a communication device (not shown). The arithmetic processing unit reads and executes the control program stored in the memory unit, thereby performing predetermined control in the control devices 30A to 30E. An example of the arithmetic processing unit is a microprocessor. An example of the memory unit is a memory.

[0050] As shown in FIG. 2 , the control device 20 includes a receiver 21 and a controller 23. Here, the receiver 21 is a device that receives the voltage measured when the fuel cell device 15 is generating power. For example, the receiver 21 may receive the voltage transmitted from the fuel cell device 15 via a communication network at a voltage stabilization timing when the fuel cell device 15 is generating power at a rated output. The "voltage stabilization timing" may be, for example, an appropriate timing during a time period (between time ta and time tb) when the voltage stabilizes after a predetermined time has elapsed since the fuel cell device 15 started generating power, as shown in FIG. 3 . Therefore, the voltage measured during power generation by the fuel cell device 15 may be the average value of the voltage during that time period (between time ta and time tb).

[0051] The controller 23 determines whether the degradation state of the fuel cell device 15 is normal or not based on a comparison between the voltage measured when the fuel cell device 15 is generating electricity and a first threshold value that decreases as the operating amount of the fuel cell device 15 increases, the first threshold value corresponding to the operating amount of the fuel cell device 15 at the time the voltage was measured. Examples of the "operating amount of the fuel cell device 15" include, but are not limited to, the cumulative power generation time or the cumulative number of times power generation has occurred. The first threshold value is a reference voltage for determining whether the degradation state of the fuel cell device 15 is normal or not when the voltage falls below the predicted state of voltage drop due to degradation of the fuel cell device 15; details of this first threshold value will be described in the first embodiment.

[0052] In this example, the controller 23 performs the above determination for each of all the power generating units 15ij (i=a to e, j=1 to n) in the fuel cell system 10, but the present invention is not limited to this.

[0053] For example, although not shown, if the fuel cell system 10 is configured with a single power generation unit, the controller 23 makes the above determination for the single power generation unit.

[0054] Furthermore, the above determination may be made for each of the power generation units 15ij (i=a to e, j=1 to n) by a control device other than the controller 23 (for example, the control devices 30A to 30E).

[0055] Furthermore, the above determination may be made for each power generation unit 15ij (i = a to e, j = 1 to n) by a control device other than the controller 23 and the control devices 30A to 30E (for example, a control device within each power generation unit not shown).

[0056] The controller 23 may be any device having a control function, and includes an arithmetic processing unit (not shown) and a storage unit (not shown) that stores a control program. The arithmetic processing unit reads and executes the control program stored in the storage unit, thereby performing predetermined control in the controller 23. An example of the arithmetic processing unit is a microprocessor. An example of the storage unit is a memory.

[0057] [Operation] Figure 4 is a flowchart showing an example of the operation of the control device in the fuel cell system of the embodiment (a control method for the fuel cell device). The following operations may be performed, for example, by the arithmetic processing unit of the controller 23 reading out a control program from the storage unit of the controller 23. However, it is not necessarily required that the following operations be performed by the controller 23. An operator may perform some of the operations. In the following example, a case where the operations are controlled by the controller 23 will be described.

[0058] First, when the control device 20 starts operating, in step S1, the voltage V measured during power generation by the fuel cell device 15 is received. Specifically, the receiver 21 receives the voltage V measured in each of the power generation units 15ij (i = a to e, j = 1 to n) via the communication network.

[0059] Here, the timing at which the voltage V is measured in each of the power generation units 15ij (i = a to e, j = 1 to n) may be, for example, the timing at which the voltage stabilizes when each of the power generation units 15ij (i = a to e, j = 1 to n) generates power at rated output.

[0060] Next, in step S2, a determination is made as to whether the degradation state of the fuel cell device 15 is normal based on a comparison between the voltage V in step S1 and a first threshold value, which decreases as the operation amount of the fuel cell device 15 increases, and which corresponds to the operation amount of the fuel cell device 15 when the voltage V was measured. Specifically, for each power generating unit 15ij (i = a to e, j = 1 to n), the voltage V in step S1 and the first threshold value are identified, and a determination is made as to whether the degradation state of each power generating unit 15ij (i = a to e, j = 1 to n) is normal based on the comparison between the two. Note that, if each of groups A to E corresponds to the fuel cell power generating device disclosed herein, a representative value of the operation amount and a representative value of the voltage V for each of groups A to E are used to determine whether the degradation state is normal. As the representative value of the operation amount for each of groups A to E, for example, the average value or median value of the operation amount of the power generating units belonging to each of groups A to E is used. As the representative value of the voltage V of each of the groups A to E, for example, the average value or median value of the voltages of the power generation units belonging to each of the groups A to E is used.

[0061] In addition, for each power generation unit 15ij (i = a to e, j = 1 to n), the operations of steps S1 and S2 may be repeated each time the cumulative power generation time, which is an example of the operating amount of the fuel cell device 15, increases by a certain amount, or each time the cumulative number of power generation events, which is an example of the operating amount of the fuel cell device 15, increases by a certain number of times.

[0062] The result of the determination of whether the degradation state of the fuel cell device 15 is normal may be notified to an external device 40 (see FIG. 2 ). The "external device 40" may be, for example, an information terminal or a display device. Examples of the information terminal include an information terminal of a consumer who receives the service of supplying power generated by the fuel cell system 10, and examples of the display device include, but are not limited to, a display device of a maintenance company. This allows consumers who receive the service of supplying power generated by the fuel cell system 10 to easily know the degradation state of the fuel cell device 15.

[0063] According to the present embodiment described above, the deterioration state of the fuel cell device 15 can be monitored more appropriately than ever before.

[0064] Specifically, according to this embodiment, compared to when the above-mentioned first threshold value for determining whether the deterioration state of the fuel cell device 15 is normal or not is not taken into consideration, it is possible to appropriately monitor whether the deterioration state of the fuel cell device 15 is normal or not in the range where the voltage V falls below the predicted state of voltage drop due to deterioration of the fuel cell device 15.

[0065] (First Example) A control method for the fuel cell device 15 of a first example of the embodiment is the same as the control method for the fuel cell device 15 of the embodiment, except for the contents described below.

[0066] In the control method for the fuel cell device 15 of this embodiment, when the voltage V measured during power generation of the fuel cell device 15 is equal to or greater than a first threshold SH1, the degradation state of the fuel cell device 15 is determined to be normal, when the voltage V is less than the first threshold SH1 and equal to or greater than a second threshold SH2 that is less than the first threshold SH1, the degradation state of the fuel cell device 15 is determined to be abnormal and power generation of the fuel cell device 15 is continued, and when the voltage V is less than the second threshold SH2, power generation of the fuel cell device 15 is stopped. In other words, even if the abnormal degradation state of the fuel cell device 15 continues, power generation of the fuel cell continues as long as the voltage V is equal to or greater than the second threshold SH2.

[0067] [Regarding the first threshold SH1 and the second threshold SH2] Figure 5 is a flowchart showing an example of a method for creating a first threshold for determining whether the deterioration state of the fuel cell device is normal or not, and a second threshold for determining whether the fuel cell device should continue generating power, in a range where the voltage has fallen below the predicted state of voltage drop due to deterioration of the fuel cell device.

[0068] Figure 6 shows an example of a first threshold value for determining whether the deterioration state of the fuel cell device is normal or not, and a second threshold value for determining whether or not to continue power generation of the fuel cell device, in a range where the voltage falls below the predicted state of voltage drop due to deterioration of the fuel cell device.

[0069] Here, the horizontal axis of Figure 6 represents the period from when the power generation time of the fuel cell device 15 is "zero" to when the cumulative power generation time reaches the end of the life of the fuel cell device 15 (hereinafter referred to as the life end determination time TE).

[0070] The vertical axis of Figure 6 represents the voltage V of the fuel cell device 15 corresponding to the accumulated power generation time of the fuel cell device 15. This voltage V is measured at appropriate times as the accumulated power generation time of the fuel cell device 15 elapses. For example, the voltage V may be measured while the fuel cell device 15 is generating power, each time the accumulated power generation time of the fuel cell device 15 increases by a predetermined power generation time. "While the fuel cell device 15 is generating power" may be, for example, the timing at which the voltage stabilizes when the fuel cell device 15 is generating power at rated output.

[0071] 5, in step S3, the initial voltage V0 is measured when the fuel cell device 15 is generating power. For example, after the fuel cell device 15 is manufactured, the initial voltage V0 may be measured at the voltage stabilization timing when the fuel cell device 15 first generates power at the rated output.

[0072] It is generally known that the voltage V of the fuel cell device 15 gradually decreases as the accumulated power generation time of the fuel cell device 15 increases, as indicated by the circle in Figure 6. In other words, the reference line R in Figure 6 corresponds to a line drawn by linearly approximating a predicted state of voltage decrease due to deterioration of the fuel cell device 15. Furthermore, the voltage V1 (the voltage indicated by the black circle in Figure 6) when the accumulated power generation time of the fuel cell device 15 is the life end determination time TE is a known, predetermined value.

[0073] 5, in step S4, a first threshold SH1 is created using the initial voltage V0 in step S3, and a second threshold SH2 is created using the voltage V1.

[0074] As shown in Figure 6, the first threshold value SH1 is determined by a straight line drawn so that the voltage V decreases as the cumulative power generation time of the fuel cell device 15 increases in the range where the voltage V falls below the predicted state of voltage drop due to deterioration of the fuel cell device 15 (see reference line R in Figure 6).

[0075] In this example, the first threshold value SH1 is determined by a straight line passing through point P0 (0, V0 - Δα), where the voltage when the power generation time of the fuel cell device 15 is "zero" is lower than the initial voltage V0 by a predetermined value Δα, and point PE (TE, V1), where the voltage when the cumulative power generation time of the fuel cell device 15 is the life end determination time TE is V1. The predetermined value Δα can be set to an appropriate voltage between the initial voltage V0 and the voltage V1. The predetermined value Δα may be, for example, approximately (V0 - V1) / 2.

[0076] As shown in FIG. 6, the second threshold value SH2 is smaller than the first threshold value SH1 and is constant regardless of the operation amount of the fuel cell device 15 (here, the cumulative power generation time).

[0077] In this example, the second threshold value SH2 is determined by a straight line passing through point P1 (0, V1) when the voltage when the power generation time of the fuel cell device 15 is "zero" is V1, and point PE (TE, V1) when the voltage when the cumulative power generation time of the fuel cell device 15 is the life end determination time TE is V1. In this case, the second threshold value SH2 is "voltage V1."

[0078] Furthermore, the first threshold value SH1, which corresponds to the operation amount when the operation amount of the fuel cell device 15 reaches a value at which the life of the fuel cell device 15 is determined to be over (here, the life end determination time TE), may be equal to or greater than the second threshold value SH2. As a result, the first threshold value SH1 decreases linearly as the operation amount of the fuel cell device 15 increases, and since the magnitude relationship between the first threshold value SH1 and the second threshold value SH2 is as described above, both threshold values ​​can be appropriately set so that the first threshold value SH1 does not become less than the second threshold value SH2 throughout the entire period until the operation amount of the fuel cell device 15 is determined to be over the life of the fuel cell device 15.

[0079] [Operation] Figure 7 is a flowchart showing an example of the operation of the fuel cell device (control method of the fuel cell device) in the fuel cell system of the first example of the embodiment. The following operation may be performed, for example, by the arithmetic processing unit of the controller 23 reading out a control program from the memory unit of the controller 23. However, it is not necessarily required that the following operation be performed by the controller 23. An operator may perform some of the operations. In the following example, a case where the operation is controlled by the controller 23 will be described.

[0080] First, when the control device 20 starts operating, in step S11, the voltage V measured during power generation by the fuel cell device 15 is received. Specifically, the receiver 21 receives the voltage V measured in each of the power generation units 15ij (i = a to e, j = 1 to n) via the communication network.

[0081] Here, the timing at which the voltage V is measured in each of the power generation units 15ij (i = a to e, j = 1 to n) may be, for example, the timing at which the voltage stabilizes when each of the power generation units 15ij (i = a to e, j = 1 to n) generates power at rated output.

[0082] In addition, for some of the power generation units 15ij (i = a to e, j = 1 to n), as shown by the triangular marks in Figure 6, as the cumulative power generation time of the power generation unit increases, the voltage V in step S11 may decrease compared to the voltage shown by the circle marks in Figure 6, deviating from the predicted state of voltage drop due to deterioration of the power generation unit (see reference line R in Figure 6).

[0083] Next, in step S21, it is determined whether the voltage V in step S11 is equal to or greater than the first threshold value SH1, which corresponds to the cumulative power generation time of the fuel cell device 15 at the time the voltage V was measured.

[0084] If the voltage V in step S11 is equal to or greater than the first threshold SH1 ("Yes" in step S21), the deterioration state of the fuel cell device 15 is determined to be normal in step S22. For example, as shown in Figure 6, when the voltage V in step S11 is a voltage corresponding to the dotted area, the deterioration state of the fuel cell device 15 is determined to be normal.

[0085] Conversely, if the voltage V in step S11 is less than the first threshold SH1 (if the answer is "No" in step S21), the process proceeds to the next determination step, where in step S23 it is determined whether the voltage V in step S11 is greater than or equal to the second threshold SH2.

[0086] If the voltage V in step S11 is equal to or greater than the second threshold SH2 (if "Yes" in step S23), the degradation state of the fuel cell device 15 is determined to be abnormal in step S24, and power generation by the fuel cell device 15 is continued. For example, as shown in Figure 6, when the voltage V in step S11 is a voltage corresponding to the shaded area between the first threshold SH1 and the second threshold SH2, the degradation state of the fuel cell device 15 is determined to be abnormal.

[0087] Conversely, if the voltage V in step S11 is less than the second threshold SH2 (if "No" in step S23), power generation by the fuel cell device 15 is stopped in step S25. For example, as shown in Figure 6, if the voltage V in step S11 is a voltage corresponding to the blackened range less than the second threshold SH2, power generation by the fuel cell device 15 is stopped. Here, if each of groups A to E corresponds to a fuel cell power generation device, power generation is stopped for all power generation units belonging to the group in which the voltage V is less than the second threshold SH2.

[0088] As described above, according to this embodiment, when the voltage V measured during power generation of the fuel cell device 15 is less than the first threshold value SH1 and greater than or equal to the second threshold value SH2 within the range where the voltage V falls below the predicted state of voltage drop due to deterioration of the fuel cell device 15 (see reference line R in Figure 6), it is possible to know that the deterioration state of the fuel cell device 15 is abnormal while continuing to generate power in the fuel cell device 15.

[0089] Furthermore, according to this embodiment, when the voltage V measured during power generation by the fuel cell device 15 is less than the second threshold value SH2, power generation by the fuel cell device 15 is stopped, thereby allowing repair or replacement of the fuel cell device 15 to be carried out in a timely manner.

[0090] The control method for the fuel cell device 15, the control device 20, and the fuel cell system 10 of this embodiment may be the same as those of the embodiment except for the above-mentioned features.

[0091] Second Example A control method for the fuel cell device 15 according to a second example of the embodiment is the same as the control method for the fuel cell device 15 according to the embodiment, except for the details described below.

[0092] In this embodiment, the control method for the fuel cell device 15 is such that, when the voltage V measured during power generation by the fuel cell device 15 is less than the first threshold value SH1 and greater than or equal to the second threshold value SH2, the fuel cell device 15 generates power under the same operating conditions as when the voltage V is greater than or equal to the first threshold value SH1.

[0093] As described above, in the control method for the fuel cell device 15 of this embodiment, even if the voltage V measured during power generation by the fuel cell device 15 is less than the first threshold value SH1 and greater than or equal to the second threshold value SH2, power generation by the fuel cell device 15 is performed while maintaining the operating conditions when the voltage V is greater than or equal to the first threshold value SH1, so output fluctuations of the fuel cell device 15 are suppressed compared to when the fuel cell device 15 generates power under operating conditions different from the operating conditions when the voltage is greater than or equal to the first threshold value.

[0094] The control method for the fuel cell device 15, the control device 20, and the fuel cell system 10 of this embodiment may be the same as those of the first embodiment or the first example of the embodiment, except for the above-mentioned features.

[0095] Third Example A control method for the fuel cell device 15 according to a third example of the embodiment is the same as the control method for the fuel cell device 15 according to the embodiment, except for the details described below.

[0096] In this embodiment, the control method for the fuel cell device 15 is such that, when the voltage V measured during power generation by the fuel cell device 15 is less than the first threshold value SH1 and greater than or equal to the second threshold value SH2, at least one of the fuel gas utilization rate and the oxidant gas utilization rate is set to be equal to or higher than when the voltage V is greater than or equal to the first threshold value SH1, thereby causing the fuel cell device 15 to generate power.

[0097] As described above, in the control method for the fuel cell device 15 of this embodiment, even if the voltage V measured during power generation by the fuel cell device 15 is less than the first threshold value SH1 and greater than the second threshold value SH2, the fuel cell device 15 generates power by setting at least one of the gas utilization rates to be equal to or higher than when the voltage V is greater than or equal to the first threshold value SH1, thereby appropriately maintaining or improving the power generation efficiency of the fuel cell device 15 compared to when the fuel cell device 15 generates power by lowering the gas utilization rate from when the voltage is greater than or equal to the first threshold value SH1.

[0098] The control method for the fuel cell device 15, the control device 20, and the fuel cell system 10 of this embodiment may be the same as those of the first embodiment or the first example of the embodiment, except for the above-mentioned features.

[0099] Fourth Example A control method for the fuel cell device 15 according to a fourth example of the embodiment is the same as the control method for the fuel cell device 15 according to the embodiment, except for the details described below.

[0100] In the control method for the fuel cell device 15 of this embodiment, when the voltage measured during power generation by the fuel cell device 15 is equal to or greater than a first threshold value SH1, the deterioration state of the fuel cell device 15 is determined to be normal, and when this voltage V is less than the first threshold value SH1, the deterioration state of the fuel cell device 15 is determined to be abnormal, and power generation by the fuel cell device 15 is continued under the same operating conditions as when the voltage V is equal to or greater than the first threshold value.

[0101] As described above, in the control method for the fuel cell device 15 of this embodiment, even if the voltage V measured during power generation by the fuel cell device 15 is less than the first threshold value SH1, power generation by the fuel cell device 15 is performed under conditions maintaining the operating conditions when the voltage V is equal to or greater than the first threshold value SH1, so it can be seen that output fluctuations of the fuel cell device 15 are suppressed compared to when the fuel cell device 15 generates power under operating conditions different from the operating conditions when the voltage is equal to or greater than the first threshold value.

[0102] The control method for the fuel cell device 15, the control device 20, and the fuel cell system 10 of this embodiment may be the same as those of the first embodiment or the first example of the embodiment, except for the above-mentioned features.

[0103] Fifth Example A control method for the fuel cell device 15 according to a fifth example of the embodiment is the same as the control method for the fuel cell device 15 according to the embodiment, except for the details described below.

[0104] In the control method for the fuel cell device 15 of this embodiment, when the voltage V measured during power generation by the fuel cell device 15 is equal to or greater than a first threshold value SH1, the deterioration state of the fuel cell device 15 is determined to be normal, and when this voltage V is less than the first threshold value SH1, the deterioration state of the fuel cell device 15 is determined to be abnormal, and at least one of the fuel gas utilization rate and the oxidant gas utilization rate is set to be equal to or higher than when the voltage V is equal to or greater than the first threshold value SH1, allowing the fuel cell device 15 to continue generating power.

[0105] As described above, in the control method for the fuel cell device 15 of this embodiment, even if the voltage V measured during power generation by the fuel cell device 15 is less than the first threshold value SH1, the fuel cell device 15 generates power by setting at least one of the gas utilization rates to be equal to or higher than when the voltage V is equal to or higher than the first threshold value SH1, thereby making it possible to appropriately maintain or improve the power generation efficiency of the fuel cell device 15 compared to when the fuel cell device 15 generates power by lowering the gas utilization rate from when the voltage is equal to or higher than the first threshold value SH1.

[0106] The control method for the fuel cell device 15, the control device 20, and the fuel cell system 10 of this embodiment may be the same as those of the first embodiment or the first example of the embodiment, except for the above-mentioned features.

[0107] (First Variant) The control method for the fuel cell device 15 in the first variant of the embodiment is the same as the control method for the fuel cell device 15 in the embodiment, except that when the deterioration state of the fuel cell device 15 is determined to be abnormal, the prediction of the replacement time for the fuel cell device 15 is revised and the revised replacement time for the fuel cell device 15 is notified to the external device 40.

[0108] Typically, the predicted value for the time to replace the fuel cell is set to a value that corresponds to normal deterioration of the fuel cell device 15. However, if the voltage V measured during power generation by the fuel cell device 15 falls below the first threshold SH1 and the deterioration state of the fuel cell device 15 is determined to be abnormal, this voltage drop is often a sign that the time to replace the fuel cell device 15 will come sooner.

[0109] Therefore, in the control method for the fuel cell device 15 of this modified example, when the deterioration state of the fuel cell device 15 is determined to be abnormal, the prediction of when to replace the fuel cell device 15 is corrected based on the measured voltage that is less than the first threshold value SH1, and this is notified to the external device 40, thereby obtaining more appropriate information regarding when to replace the fuel cell device 15 than when such a prediction of when to replace the fuel cell device 15 is not corrected.

[0110] Other than the above features, the control method of the fuel cell device 15, the control device 20, and the fuel cell system 10 of this modified example may be the same as the embodiment and any of the first to fifth examples of the embodiment.

[0111] (Second Variant) The control method for the fuel cell device 15 in the second variant of the embodiment is the same as the control method for the fuel cell device 15 in the embodiment, except that when the deterioration state of the fuel cell device 15 is determined to be abnormal, the prediction of the maintenance time for the fuel cell device 15 is revised and the revised maintenance time for the fuel cell device 15 is notified to the external device 40.

[0112] Typically, the predicted value for the maintenance timing of the fuel cell is set to a value corresponding to normal deterioration of the fuel cell device 15. However, if the voltage V measured during power generation by the fuel cell device 15 falls below the first threshold SH1 and the deterioration state of the fuel cell device 15 is determined to be abnormal, this voltage drop is often a sign that the maintenance timing of the fuel cell device 15 will come sooner.

[0113] Therefore, in the control method for the fuel cell device 15 of this modified example, when the deterioration state of the fuel cell device 15 is determined to be abnormal, the prediction of the maintenance time for the fuel cell device 15 is corrected based on the measured voltage that is less than the first threshold value SH1, and this is notified to the external device 40, thereby obtaining more appropriate information regarding the maintenance time for the fuel cell device 15 than when such a prediction of the maintenance time is not corrected.

[0114] Other than the above features, the control method of the fuel cell device 15, the control device 20, and the fuel cell system 10 of this modified example may be the same as the embodiment and any of the first to fifth examples of the embodiment.

[0115] The first to fifth embodiments of the embodiment and the first to second modified embodiments of the embodiment may be combined with each other as long as they do not exclude each other. From the above description, many improvements and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present disclosure. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present disclosure.

[0116] An aspect of the present disclosure can be used in a control method, a control device, and a fuel cell system for a fuel cell device, which can monitor the degradation state of the fuel cell device more appropriately than ever before.

[0117] 10: Fuel cell system 15: Fuel cell device 15ij: Power generation unit 20: Control device 21: Receiver 23: Controller 30A: Control device 30B: Control device 30C: Control device 30D: Control device 30E: Control device 40: External device SH1: First threshold SH2: Second threshold a1 to an: Power generation unit b1 to bn: Power generation unit c1 to cn: Power generation unit d1 to dn: Power generation unit e1 to en: Power generation unit

Claims

1. receiving a voltage measured during power generation by the fuel cell device; A control method for a fuel cell device, which determines whether the deterioration state of the fuel cell device is normal or not based on a comparison between the voltage and a first threshold value that decreases as the operating amount of the fuel cell device increases, the first threshold value corresponding to the operating amount of the fuel cell device at the time the voltage is measured.

2. When the voltage is equal to or greater than the first threshold value, the deterioration state of the fuel cell device is determined to be normal, and power generation of the fuel cell device is continued; When the voltage is less than the first threshold value and equal to or greater than a second threshold value that is smaller than the first threshold value, the deterioration state of the fuel cell device is determined to be abnormal, and power generation of the fuel cell device is continued; 2. The control method for a fuel cell device according to claim 1, further comprising the step of stopping power generation of the fuel cell device when the voltage is less than the second threshold value.

3. 3. The control method for a fuel cell device according to claim 2, wherein the first threshold value corresponding to the operating amount of the fuel cell device when the operating amount is a value that is determined to be the end of the life of the fuel cell device is equal to or greater than the second threshold value.

4. 4. The control method for a fuel cell device according to claim 2, wherein the second threshold value is constant regardless of an operating amount of the fuel cell device.

5. A control method for a fuel cell power generation device described in any one of claims 2 to 4, wherein when the voltage is less than the first threshold and greater than or equal to the second threshold, the fuel cell device is caused to generate power under the same operating conditions as when the voltage is greater than or equal to the first threshold.

6. A control method for a fuel cell power generation device described in any one of claims 2 to 4, wherein when the voltage is less than the first threshold and greater than or equal to the second threshold, at least one of the fuel gas utilization rate and the oxidant gas utilization rate is made equal to or higher than when the voltage is greater than or equal to the first threshold, thereby causing the fuel cell device to generate power.

7. When the voltage is equal to or greater than the first threshold value, the deterioration state of the fuel cell device is determined to be normal; 2. The control method for a fuel cell device according to claim 1, wherein when the voltage is less than the first threshold, the deterioration state of the fuel cell device is judged to be abnormal, and power generation of the fuel cell device is continued under the same operating conditions as when the voltage is equal to or greater than the first threshold.

8. When the voltage is equal to or greater than the first threshold value, the deterioration state of the fuel cell device is determined to be normal; 2. A control method for a fuel cell device as described in claim 1, wherein when the voltage is less than the first threshold, the deterioration state of the fuel cell device is determined to be abnormal, and at least one of the fuel gas utilization rate and the oxidant gas utilization rate is set to be equal to or higher than when the voltage is equal to or higher than the first threshold, thereby allowing the fuel cell device to continue generating power.

9. 5. The method for controlling a fuel cell device according to claim 1, further comprising the step of notifying an external device of the result of determining whether the deterioration state of the fuel cell device is normal.

10. A control method for a fuel cell device described in any one of claims 1 to 4, wherein when the deterioration state of the fuel cell device is determined to be abnormal, a prediction of when to replace the fuel cell device is revised and the revised replacement time of the fuel cell device is notified to an external device.

11. A control method for a fuel cell device described in any one of claims 1 to 4, wherein when the deterioration state of the fuel cell device is determined to be abnormal, a prediction of the maintenance time for the fuel cell device is revised and the revised maintenance time for the fuel cell device is notified to an external device.

12. a receiver for receiving a voltage measured during power generation by the fuel cell device; A control device comprising: a controller that determines whether the deterioration state of the fuel cell device is normal or not based on a comparison between the voltage and a first threshold value that decreases as the operating amount of the fuel cell device increases, the first threshold value corresponding to the operating amount of the fuel cell device at the time the voltage is measured.

13. a fuel cell device; A fuel cell system comprising the control device according to claim 12.