fuel cell system

Abstract

To provide a fuel cell system that can perform and stop operation of a solid oxide fuel cell at appropriate timing while considering a response to outage in the future.SOLUTION: A fuel cell system comprises: an operation determination unit 53 that on the basis of a result of operation propriety determination processing of temporarily determining operation of a solid oxide fuel cell 1 should be performed or stopped and a result of outage possibility determination processing of determining high / low of possibility of outage occurrence during an outage determination period in the future, outputs a result of determining the operation of the solid oxide fuel cell 1 should be performed or stopped; a threshold value setting unit 52 that sets a determination threshold value; and an operation control unit 54 that on the basis of the determination result output by the operation determination unit 53, gives an operation performing instruction or an operation stop instruction for the solid oxide fuel cell 1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fuel cell system that supplies energy generated from a solid oxide fuel cell that can be selectively controlled to operate or stop its operation to an energy load section. [Background technology]

[0002] Fuel cells, particularly solid oxide fuel cells, are highly efficient but have low tolerance for start-stops, making continuous operation suitable. Fuel cells are, of course, capable of load-following operation, which changes the power they generate according to the magnitude of the power load on the power load section. However, when the power load or heat load is very small, even if the fuel cell is operated at minimum output, excess power and heat will be generated by the fuel cell, reducing the operational benefits that would be obtained by operating the fuel cell (for example, reductions in primary energy consumption, energy costs, and carbon dioxide emissions). Therefore, when the power load or heat load is very small, it is necessary to stop the fuel cell's operation.

[0003] Patent Document 1 (JP 2011-198768 A) discloses a control system that automatically shuts down a solid oxide fuel cell when the power supply from the solid oxide fuel cell to a load remains below a certain level for a certain period of time, and automatically starts up the solid oxide fuel cell when the power supply from the grid to the load remains above a certain level for a certain period of time. Furthermore, it also discloses a daily start-stop operation (DSS) that stops power generation at night when power consumption is low, and starts up in the morning.

[0004] Patent Document 2 (JP Patent Publication No. 2017-174750) describes a system that, rather than operating a fuel cell in a manner similar to DSS operation, which involves repeatedly stopping and starting the fuel cell in short intervals, determines the magnitude of the operating benefits of the fuel cell over a relatively long period of time, and operates the fuel cell if the operating benefits are large, and stops the operation if the operating benefits are small. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-198768 [Patent Document 2] JP 2017-174750 A Summary of the Invention [Problem to be solved by the invention]

[0006] Furthermore, if a power outage occurs and the fuel cell system is stopped, the power supply cannot be received, so it may not be advisable to stop the fuel cell system even if there is little benefit to operating it.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a fuel cell system that can operate and stop a solid oxide fuel cell at appropriate times while taking into account how to respond to future power outages. [Means for solving the problem]

[0008] A characteristic configuration of a fuel cell system according to the present invention for achieving the above object is a fuel cell system that supplies energy generated from a solid oxide fuel cell that can be selectively controlled to operate or stop its operation to an energy load unit, and a load measuring unit that measures load energy required by the energy load unit; a load calculation unit that calculates an average calculation value of the load measurement values ​​of the load measurement unit measured over a predetermined determination period; a result of an operation possibility determination process that makes a provisional determination as to whether the solid oxide fuel cell should be operated or stopped based on the average calculation value or a substitute value derived from the average calculation value and a determination threshold value; and a result of a power outage possibility determination process that determines the likelihood of a power outage occurring in a future power outage determination period. a result of a cost verification process for verifying a first operating cost required to continue operation of the solid oxide fuel cell until the predicted power outage date and time within the power outage determination period when there is a high possibility of a power outage occurring during the power outage determination period, and a second operating cost required to complete start-up of the solid oxide fuel cell at the predicted power outage date and time after stopping operation of the solid oxide fuel cell;an operation determination unit that outputs a determination result indicating whether the solid oxide fuel cell should be operated or stopped based on the result; a threshold value setting unit that sets the determination threshold value; an operation control unit that issues an operation execution command or an operation stop command to the solid oxide fuel cell based on the determination result output by the operation determination unit; 、 The operation determination unit outputs the determination result that the operation of the solid oxide fuel cell should be stopped when the operation possibility determination process provisionally determines that the operation should be stopped, the power outage possibility determination process determines that there is a high possibility of a power outage, and the cost verification process determines that the first operating cost is greater than the second operating cost. It's at the point.

[0009] Here, the alternative value is a function value of an operating merit function that derives the operating merit of the solid oxide fuel cell from the average calculated value, and the threshold setting unit may set a judgment threshold converted into the operating merit as the merit judgment threshold. The operational merit may be a reduction in primary energy consumption, a reduction in energy costs, or a reduction in carbon dioxide emissions obtained by operating the solid oxide fuel cell, or a combination thereof.

[0010] According to the above characteristic configuration, the operation determination unit determines whether the solid oxide fuel cell should be operated or stopped based on the result of an operation feasibility determination process that makes a provisional determination as to whether the operation should be continued or stopped based on either an average calculated value of load measurement values ​​measured over a predetermined determination period by a load measurement unit that measures load energy required by an energy load unit or a substitute value derived from the average calculated value and a determination threshold value, and the result of a power outage possibility determination process that determines the likelihood of a power outage occurring in a future power outage determination period. a result of a cost verification process for verifying a first operating cost required to continue operation of the solid oxide fuel cell until the predicted power outage date and time within the power outage determination period when there is a high possibility of a power outage occurring during the power outage determination period, and a second operating cost required to complete start-up of the solid oxide fuel cell at the predicted power outage date and time after stopping operation of the solid oxide fuel cell; The operation control unit outputs a determination result that the solid oxide fuel cell should be operated or stopped based on the determination result output by the operation determination unit, and issues an operation execution command or an operation stop command to the solid oxide fuel cell based on the determination result output by the operation determination unit. In other words, the operation determination unit determines the determination result that the solid oxide fuel cell should be operated or stopped not by taking into account only the past load energy value, but also by taking into account the likelihood of a power outage occurring in a future power outage determination period. In addition, even if the power outage possibility determination process determines that there is a high possibility of a power outage, i.e., even if it seems preferable to operate the solid oxide fuel cell, if the cost verification process determines that the first operating cost is greater than the second operating cost, i.e., if it would be less costly to temporarily stop operation of the solid oxide fuel cell and then complete startup at the predicted power outage date and time, the operation determination unit outputs a determination result that the operation of the solid oxide fuel cell should be stopped.In other words, it is possible to operate the solid oxide fuel cell so as to reduce costs while ensuring that the solid oxide fuel cell is in operation at the predicted power outage date and time. Therefore, it is possible to provide a fuel cell system that can start and stop operation of the solid oxide fuel cell at appropriate times while taking into consideration how to deal with future power outages.

[0011] Another characteristic configuration of the fuel cell system according to the present invention is: The operation determination unit outputs the determination result that the solid oxide fuel cell should be operated when the operation possibility determination process provisionally determines that the operation should be stopped, the power outage possibility determination process determines that there is a high possibility of a power outage, and the cost verification process determines that the first operating cost is not greater than the second operating cost. It's at the point.

[0012] According to the above characteristic configuration, In the operation feasibility determination process, it is provisionally determined that operation should be stopped, and in the power outage possibility determination process, it is determined that there is a high possibility of a power outage occurring, and in the cost verification process, it is determined that the first operating cost is not greater than the second operating cost. When the power supply is turned on, the solid oxide fuel cell can be kept in operation, so that even if a power outage occurs, power can be supplied from the fuel cell system.

[0013] Another characteristic feature of the fuel cell system according to the present invention is that, when the operation control unit provisionally determines in the operation feasibility determination process that operation should be performed, it outputs the determination result that the solid oxide fuel cell should be operated.

[0014] According to the above-described characteristic configuration, if the operation feasibility determination process provisionally determines that operation should be performed, the solid oxide fuel cell can be left in operation, and as a result, power can be supplied from the fuel cell system.

[0015] Another characteristic feature of the fuel cell system of the present invention is that when the operation control unit provisionally determines in the operation feasibility determination process that operation should be stopped and the power outage possibility determination process determines that the possibility of a power outage is low, it outputs the determination result that operation of the solid oxide fuel cell should be stopped.

[0016] According to the above characteristic configuration, if the operation feasibility determination process provisionally determines that operation should be stopped and the power outage possibility determination process determines that the possibility of a power outage is low, the operation of the solid oxide fuel cell can be stopped, thereby avoiding the solid oxide fuel cell from continuing to operate in a state where there is little benefit to operating it. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing a basic configuration of equipment including a fuel cell system. [Figure 2] FIG. 2 is a diagram showing the flow of information in control of selecting whether to operate or stop the operation of a solid oxide fuel cell in a fuel cell system. [Figure 3] 5A and 5B are diagrams illustrating various calculation values ​​calculated based on load measurement values. [Figure 4] 10 is a graph showing the relationship between the standard deviation of the load measurement value and the merit determination threshold value. [Figure 5] 4 is a flowchart illustrating a determination as to whether to operate or stop the solid oxide fuel cell of the first embodiment. [Figure 6] 10 is a flowchart illustrating a driving possibility determination process. [Figure 7] 10 is a flowchart illustrating another driving possibility determination process. [Figure 8] FIG. 1 is a functional block diagram illustrating an example of an embodiment of a fuel cell system. [Figure 9] 10 is a flowchart illustrating a determination as to whether to operate or stop the solid oxide fuel cell of the second embodiment. [Figure 10] 10 is a flowchart illustrating a determination as to whether to operate or stop the solid oxide fuel cell of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] First Embodiment A fuel cell system according to a first embodiment of the present invention will be described below with reference to the drawings. First, the basic configuration of equipment including a fuel cell system according to the present invention will be described with reference to the functional block diagram of FIG. 1. As shown in FIG. 1, the fuel cell system includes a solid oxide fuel cell 1 that supplies energy generated by operation to an energy load unit L, and an operation control device 100 that controls the operation of the solid oxide fuel cell 1. The energy load unit L is composed of a power load unit 3 and a heat load unit 4. Electrical energy generated by operation of the solid oxide fuel cell 1 is supplied to the power load unit 3, and thermal energy generated by operation of the solid oxide fuel cell 1 is supplied to the heat load unit 4. The power load unit 3 can consume power supplied from a commercial power source 15, and the heat load unit 4 can consume heat supplied from, for example, an auxiliary heat source device 11 that generates heat by burning fuel. The operation control device 100 can be implemented using a computer system having information processing, information storage, and information communication functions.

[0025] [Power supply to power load unit 3] The power generated by the solid oxide fuel cell 1 is supplied to an inverter 12. The inverter 12 adjusts the power generated by the solid oxide fuel cell 1 to the same voltage and frequency as the power received from a commercial power source 15. The operation of the inverter 12 is controlled by an operation control device 100. The inverter 12 is electrically connected to a received power supply line 14 via a generated power supply line 13. The power generated from the solid oxide fuel cell 1 is supplied to a power load unit 3 via the inverter 12, the generated power supply line 13, and the received power supply line 14. Since the received power supply line 14 is connected to the commercial power source 15, power is supplied to the power load unit 3 from at least one of the solid oxide fuel cell 1 and the commercial power source 15.

[0026] The incoming power supply line 14 is provided with a power load measuring means 16 as a load measuring unit S that measures the power load of the power load unit 3. The operation control device 100 performs control so that the generated power supplied from the solid oxide fuel cell 1 to the incoming power supply line 14 by the inverter 12 is equal to the power load detected by the power load measuring means 16. However, if the power load detected by the power load measuring means 16 is smaller than the minimum generated power of the solid oxide fuel cell 1 (i.e., the minimum generated power supplied to the incoming power supply line 14 by the inverter 12), surplus power is generated. In such a case, the surplus power is consumed by an electric heater 9 for consuming surplus power, which converts power into heat and recovers it.

[0027] The electric heater 9 is made up of multiple resistance heaters, and heats the cooling water for the solid oxide fuel cell 1 that flows through the exhaust heat recovery path 6 when the exhaust heat recovery pump 7 is activated. The electric heater 9 is turned on and off by an activation switch 10 connected to the output side of the inverter 12. The activation switch 10 is also switched so that the power consumption of the electric heater 9 increases as the amount of surplus power in the solid oxide fuel cell 1 increases. The operation of the activation switch 10 is controlled by an operation control device 100.

[0028] It is possible to appropriately set what devices are included in the power load unit 3. For example, it is possible to set the power load unit 3 of this embodiment to exclude auxiliary equipment used to operate the solid oxide fuel cell 1, an antifreeze heater that prevents the hot water supplied to the heat load unit 4 from freezing, and the like. In addition, the standby power of the power load unit 3 may be subtracted from the power load measured in this embodiment.

[0029] [Supply of heat to heat load section 4] The hot water storage tank 2 stores heat generated by the solid oxide fuel cell 1 in the form of hot water. In this embodiment, the hot water is stored in the hot water storage tank 2 in a state that forms temperature stratification. That is, the hot water storage tank 2 is configured so that relatively low-temperature hot water is stored in the lower part and relatively high-temperature hot water is stored in the upper part. The hot water stored in the hot water storage tank 2 circulates between the solid oxide fuel cell 1 and the hot water storage tank 2 through the exhaust heat recovery path 6. The flow of hot water in the exhaust heat recovery path 6 is controlled by an exhaust heat recovery pump 7. The operation of the exhaust heat recovery pump 7 is controlled by the operation control device 100. For example, when the operation of the solid oxide fuel cell 1 is started and it becomes necessary to cool the solid oxide fuel cell 1, the operation control device 100 operates the exhaust heat recovery pump 7 to flow the relatively low-temperature hot water stored in the lower part of the hot water storage tank 2 into the exhaust heat recovery path 6. That is, the hot water circulating through the exhaust heat recovery path 6 is used as cooling water for the solid oxide fuel cell 1. The relatively low-temperature hot water flowing through the exhaust heat recovery path 6 recovers the heat emitted from the solid oxide fuel cell 1 (i.e., the hot water is heated by the exhaust heat from the solid oxide fuel cell 1), and becomes relatively high-temperature hot water, which flows into the top of the hot water storage tank 2.

[0030] In addition, a radiator 8 is installed in the exhaust heat recovery path 6 to radiate heat from the hot water flowing from the hot water storage tank 2 to the solid oxide fuel cell 1 through the exhaust heat recovery path 6. The operation control device 100 stops the operation of this radiator 8 when the temperature of the hot water flowing from the hot water storage tank 2 to the solid oxide fuel cell 1 is below a set upper limit temperature. However, when the temperature of the hot water flowing from the hot water storage tank 2 to the solid oxide fuel cell 1 is equal to or higher than the set upper limit temperature (i.e., when the hot water cannot adequately cool the solid oxide fuel cell 1), the operation control device 100 activates the radiator 8 to radiate heat and lower the temperature of the hot water. In addition, Joule heat generated by energizing the electric heater 9 described above is recovered by the hot water flowing from the solid oxide fuel cell 1 to the hot water storage tank 2 in the exhaust heat recovery path 6.

[0031] Relatively high-temperature hot water stored in the upper part of the hot water storage tank 2 is supplied to the heat load section 4 through the hot water supply path 5 connected to the upper part of the hot water storage tank 2. The heat load section 4 is used for hot water supply or heating, etc. When the heat load section 4 is used for hot water supply, the hot water does not return to the hot water storage tank 2. When the heat load section 4 is used for heating, only the heat contained in the hot water is consumed and the hot water may return to the hot water storage tank 2. The hot water supply path 5 is provided with an auxiliary heat source device 11 for heating the hot water flowing through the hot water supply path 5. When the temperature of the hot water flowing out from the upper part of the hot water storage tank 2 is lower than the temperature of the hot water required by the heat load section 4, the operation control device 100 operates the auxiliary heat source device 11 to control the temperature of the hot water supplied to the heat load section 4 to the desired temperature. A heat load measurement means 17 is provided in the hot water supply path 5 as a load measurement section S for measuring the amount of heat consumed by the heat load section 4.

[0032] The operator of the fuel cell system can use an information input / output device IOD that exchanges information with the operation control device 100. The information input / output device IOD includes a communication terminal that is generally installed under the name of a bathroom remote control or a kitchen remote control, and such a remote control is equipped with operation buttons, an information display unit, an audio output unit, etc.

[0033] Next, using Figure 2, we will explain the flow of information in the control that selects whether to operate (including continuing operation and starting a new operation) or stop operation (including continuing stop and stopping a new operation) of the solid oxide fuel cell 1 in the fuel cell system. 2, the operation control device 100 receives the load measurement value (indicated by Lo in FIG. 2) from the load measurement unit S and power outage related information from the information providing server 300, and outputs an operation execution command or an operation stop command to the solid oxide fuel cell 1. The load measurement unit S measures the load energy required by the energy load unit L at predetermined sampling intervals (for example, one hour to several hours) over a predetermined determination period (for example, one month), and repeats the measurement process of sending the load measurement value to the operation control device 100.

[0034] In the example shown in FIG. 2, the functional units that execute the basic functions of the operation control device 100 are a load calculation unit 51, a threshold setting unit 52, an operation determination unit 53, and an operation control unit 54. The load calculation unit 51 calculates an average calculated value of the load measurement values. The average calculated value can be a value that represents a group of load measurement values ​​over a predetermined period, such as an arithmetic mean value, a weighted mean value, a median value, or a mode value. Generally, the arithmetic mean value is used. When the operation control device 100 handles not only the average calculated value but also a substitute value derived from this average calculated value, the load calculation unit 51 calculates this substitute value. The substitute value is a function value derived using the average calculated value as a variable, i.e., a conversion value. Here, the substitute value is a function value of an operating merit function that derives the operating merit of the solid oxide fuel cell 1 from the average calculated value. In other words, if the average calculated value is E and the substitute value (operating merit value) is M, the function formula can be expressed as M=h(E). The operating merit is the reduction in primary energy consumption, energy cost reduction, or carbon dioxide emission reduction, or a combination of these, obtained by operating the solid oxide fuel cell 1, and the operating merit increases as the load increases. However, since there is a limit to the amount of load that the solid oxide fuel cell 1 can handle, the increase in the operating merit gradually levels off in areas with high loads. For example, if the horizontal axis represents the load and the vertical axis represents the operating merit, the graph shape of the operating merit function will resemble a logarithmic function. In practice, the operating merit function can be determined by statistical processing using experimental values, empirical values, etc.

[0035] The operation determination unit 53 can perform an operation feasibility determination process that makes a provisional determination as to whether the solid oxide fuel cell 1 should be operated or stopped based on either the average calculation value or an alternative value derived from the average calculation value and a determination threshold value, and a power outage possibility determination process that determines the likelihood of a power outage occurring during a future power outage determination period.

[0036] [Drivability determination process] The operation determination unit 53 compares the average calculated value or the alternative value (operation merit value) with the corresponding determination threshold, and if the value exceeds the determination threshold, provisionally determines that operation should be performed, and if the value is equal to or less than the determination threshold, provisionally determines that operation should be stopped.

[0037] In the basic configuration of the threshold setting unit 52, when an average calculated value is used for the operation judgment, the threshold setting unit 52 pre-calculates, as a judgment threshold Th, a boundary value between a region of average calculated values ​​where it is considered better to operate the solid oxide fuel cell 1 and a region of average calculated values ​​where it is considered better to suspend operation of the solid oxide fuel cell 1. When an alternative value (operation merit value) that is a function value of an operation merit function is used for the operation judgment, the threshold setting unit 52 pre-calculates, as a merit judgment threshold mTh (a judgment threshold converted into an operation merit value), a boundary value between a region of alternative values ​​where it is considered better to operate the solid oxide fuel cell 1 and a region of alternative values ​​where it is considered better to suspend operation of the solid oxide fuel cell 1.

[0038] If the average calculation value or the alternative value is simply used for the operation judgment, the variability of the load measurement values ​​used as the original data for calculating the average calculation value will not be taken into consideration. This means that the same operation judgment may be made when the load measurement values ​​are distributed over a wide range and when the load measurement values ​​are densely distributed around a specific value. According to the knowledge of the present inventors, a state in which the load measurement values ​​are distributed variably has greater operational benefits than a state in which the load measurement values ​​are densely distributed.

[0039] A method for incorporating the degree of variation in load measurement values ​​into driving judgment will be described using FIG. 3. The load calculation unit 51 calculates the standard deviation (indicated by σ in FIG. 3) for the target period based on the load measurement values ​​included in each section into which the target period is divided. The average calculated value of the load measurement values ​​sampled during the target period is indicated by E, and the average calculated value of the load measurement values ​​for each section is indicated by ei (i is a subscript that identifies the section). The standard deviation σ is calculated using a well-known formula from k average calculated values ​​ei. Furthermore, the load calculation unit 51 calculates an evaluation merit value that takes into account the degree of variation in the load measurement values. The first value is a function value derived from the driving merit function using a lower value obtained by subtracting the standard deviation from the average calculated value, and the second value is a function value derived from the driving merit function using an upper value obtained by adding the standard deviation to an alternative value. For example, the average value between the first value and the second value. The calculation of this evaluation merit value can be expressed by the formula MV=(1 / 2)×(h(E-σ)+h(E+σ)). Here, MV is the evaluation merit value, σ is the standard deviation, E is the average calculated value, and h() is the operation merit function. The evaluation merit value calculated in this way is compared with a merit determination threshold mTh by the operation determination unit 53, and a provisional determination is made as to whether the solid oxide fuel cell 1 should be operated or stopped.

[0040] A method for incorporating the degree of variation in load measurement values ​​into operation judgment, other than the method of using an evaluation merit value calculated using the standard deviation of the load measurement values ​​as a variable, is described below. In this method, the threshold setting unit 52 sets a function value derived using the standard deviation calculated by the load calculation unit 51 as described above as the merit judgment threshold. In other words, the merit judgment threshold is changed depending on the degree of variation in the load measurement values. Specifically, the merit judgment threshold is set as a function value of the standard deviation of the load measurement values ​​(daily load), and this function increases the merit judgment threshold as the standard deviation increases. Figure 4 shows an example of such a function in graph form. In this way, by using a merit judgment threshold that dynamically changes depending on the standard deviation of the load measurement values, the degree of variation in the load measurement values ​​can be incorporated into operation judgment. When the energy load measured by the load measurement unit S and used for operation judgment includes both thermal load energy and power load energy, a function can be used to derive an integrated load measurement value using the load measurement value of thermal load energy and the load measurement value of power load energy as variables. By using this integrated load measurement value as the load measurement value, the above-mentioned operation determination can be made.

[0041] [Power outage possibility determination process] For example, information regarding the scheduled power outage date and time for a planned power outage is transmitted to the operation determination unit 53 as power outage-related information from the information providing server 300. Then, if the scheduled power outage date and time exists within a future power outage determination period, the operation determination unit 53 determines that there is a high possibility that a power outage will occur during that power outage determination period, and if there is no scheduled power outage date and time within the future power outage determination period, the operation determination unit 53 determines that there is a low possibility that a power outage will occur during that power outage determination period.

[0042] Alternatively, the operation determination unit 53 receives, from the information providing server 300, weather information such as predicted typhoon path information, predicted central pressure, and predicted maximum wind speed as power outage-related information. The information providing server 300 also transmits actual power outage occurrence status and other information as power outage-related information. If the weather information predicts that a typhoon will pass within a set distance during a future power outage determination period, the operation determination unit 53 determines that a power outage is highly likely to occur during that power outage determination period. If the weather information predicts that a typhoon will not pass within a set distance during a future power outage determination period, the operation determination unit 53 determines that a power outage is unlikely to occur during that power outage determination period. When determining that a power outage is highly likely, the operation determination unit 53 may set the predicted power outage date and time to the date and time when the installation location of the fuel cell system, which can be identified by, for example, the customer's address, is predicted to be within a set distance from the typhoon's center or the date and time when the installation location is predicted to be within the typhoon's storm zone.

[0043] The conditions under which the operation determination unit 53 determines that a power outage is likely to occur can be set as appropriate. For example, the operation determination unit 53 may determine that a power outage is likely to occur if a typhoon will pass within a set distance within a future power outage determination period and the predicted central pressure of the typhoon at the date and time when the typhoon is predicted to enter within the set distance is below 960 hPa. Alternatively, the operation determination unit 53 may determine that a power outage is likely to occur if a typhoon will pass within a set distance within a future power outage determination period and the predicted maximum wind speed of the typhoon at the date and time when the typhoon is predicted to enter within the set distance is 33 m / s or higher. Alternatively, the operation determination unit 53 may determine that a power outage is likely to occur if a typhoon will pass within a set distance within a future power outage determination period and a power outage has already occurred in the area where the typhoon passed.

[0044] FIG. 5 is a flowchart illustrating the determination made by the operation determination unit 53 as to whether to operate or stop the solid oxide fuel cell 1. In FIG. In step #10, the operation determination unit 53 determines whether it is the timing for operation determination, that is, whether it is the day to determine whether operation / stop is to be performed. For example, if the timing for this operation determination is set to once a month at the end of the month, and the operation determination unit 53 determines using the calendar function that the current time is the end of the month (determined as "Yes" in step #10), it proceeds to step #11. On the other hand, if the operation determination unit 53 determines using the calendar function that the current time is not the end of the month (determined as "No" in step #10), it repeats the determination in step #10.

[0045] In step #11, the operation determination unit 53 performs an operation feasibility determination process. FIG. 6 is a flowchart illustrating the operation feasibility determination process. In this case, the operation determination unit 53 reads the power load measurement values ​​accumulated by the load calculation unit 51 over the determination period (one month) and calculates an average calculated value, which is, for example, a power load measurement value per day, for example, by using the arithmetic mean (step #30). The operation determination unit 53 compares the calculated average calculated value with a determination threshold value set by the threshold setting unit 52, for example, 4.1 kWh / day (step #31). If the average calculated value is equal to or greater than the determination threshold value (if "Yes" in step #31), the operation determination unit 53 provisionally determines that operation should be performed (step #32). If the average calculated value is below the determination threshold value (if "No" in step #31), the operation determination unit 53 provisionally determines that operation should be stopped (step #33).

[0046] FIG. 7 is a flowchart illustrating another operation feasibility determination process. In this case, the operation determination unit 53 reads the power load measurement values ​​accumulated by the load calculation unit 51 over the determination period (one month), calculates the average calculation value (e.g., arithmetic mean value), and derives an evaluation merit value from the average calculation value using an operation merit function (step #40). The operation determination unit 53 compares the derived evaluation merit value with the merit determination threshold value set by the threshold setting unit 52 (step #41). If the evaluation merit value is equal to or greater than the merit determination threshold value ("Yes" in step #41), the operation determination unit 53 provisionally determines that operation should be performed (step #42). If the evaluation merit value is below the merit determination threshold value ("No" in step #41), the operation determination unit 53 provisionally determines that operation should be stopped (step #43).

[0047] Next, in step #12 of Figure 5, the driving judgment unit 53 proceeds to step #13 if the result of the provisional judgment of the driving feasibility judgment process is that driving is stopped, and proceeds to step #16 if the result of the provisional judgment of the driving feasibility judgment process is that driving is to be performed.

[0048] In step #13, the operation determination unit 53 performs a power outage possibility determination process, and if a planned power outage date and time exists within the future power outage determination period, it determines that there is a high possibility of a power outage occurring during that power outage determination period, and if there is no planned power outage date and time within the future power outage determination period, it determines that there is a low possibility of a power outage occurring during that power outage determination period.Then, in step #14, if the operation determination unit 53 determines that there is a high possibility of a power outage occurring, it proceeds to step #16, and if it determines that there is a low possibility of a power outage occurring, it proceeds to step #17.

[0049] In step #16, the operation determination unit 53 outputs a determination result that operation should be performed to the operation control unit 54. In step #17, the operation determination unit 53 outputs a determination result that operation should be stopped to the operation control unit 54. Then, the operation control unit 54 outputs an operation execution command or an operation stop command to the solid oxide fuel cell 1 based on the determination result of the operation determination unit 53.

[0050] As described above, in this embodiment, even if the operation feasibility determination process provisionally determines that operation should be stopped, if the power outage possibility determination process determines that a power outage is highly likely, the operation control unit 54 is configured to issue an operation execution command to the solid oxide fuel cell 1. Furthermore, if the operation feasibility determination process provisionally determines that operation should be carried out, the operation control unit 54 is configured to issue an operation execution command to the solid oxide fuel cell 1. Furthermore, if the operation feasibility determination process provisionally determines that operation should be stopped and if the power outage possibility determination process determines that a power outage is unlikely, the operation control unit 54 is configured to issue an operation stop command to the solid oxide fuel cell 1.

[0051] When this operation control device 100 is used, the operation of the solid oxide fuel cell 1 is automatically started or stopped based on the determination result of the operation determination unit 53. However, if the final decision on whether to start or stop operation is left to the user, the determination result of the operation determination unit 53 is notified to the user via a remote control, which is generally installed under the name of a bathroom remote control, kitchen remote control, or the like, and an operation start command or operation stop command is given in response to an instruction from the user using the remote control.

[0052] Next, several operating modes of the above-mentioned fuel cell system will be described. An example of a common system configuration that can realize these operating modes is shown in Figure 8. Here, the operation control device 100 is equipped with each functional unit described using Figure 2, and a remote control LC installed in a bathroom or kitchen is used as the information input / output device IOD of the operation control device 100. Furthermore, the operation control device 100 can be connected via a communication unit 50 to a remote management center (management computer) 200 operated by a management company that manages this fuel cell system so as to be able to exchange data, and can also be connected to an information providing server 300 so as to be able to exchange data.

[0053] Here, the load calculation unit 51, threshold value setting unit 52, driving determination unit 53, and driving control unit 54, which constitute the functions of the driving control device 100, are similar to those described with reference to FIG. 2. In addition to the above, the driving control device 100 also includes an driving merit function storage unit 55, an output data processing unit 56, an input data processing unit 57, and a notification processing unit 58. In this embodiment, the driving merit function storage unit 55 stores, in the form of a lookup table, the driving merit function M=h(E), which derives the driving merit value (a type of alternative value): M, which indicates the driving merit, from the average calculated value: E calculated by the load calculation unit 51, as described with reference to FIGS. 2 and 3. Furthermore, the driving merit function storage unit 55 stores, in the form of a lookup table, a formula for deriving an evaluated merit value from the average calculated value: E and standard deviation: σ calculated by the load calculation unit 51, i.e., MV=(½)×(h(E−σ)+h(E+σ)). In this equation as well, the operating merit function is used, so the above two lookup tables can be constructed in an integrated manner.

[0054] The output data processing unit 56 transmits control signals for controlling various operating devices in the fuel cell system as shown in FIG. 1 based on commands from the operation control unit 54. The operating devices to be controlled include fuel cell operating device D1 for operating the solid oxide fuel cell 1, power system operating device D2 for supplying power to the power load unit 3, and hot water system operating device D3 for supplying hot water to the heat load unit 4 such as a water heater. Furthermore, the output data processing unit 56 transmits an alarm signal to an alarm device 60 incorporated in the remote control LC. The alarm device 60 includes a display 61 such as an LCD, a buzzer 62, and a lamp 63, and the alarm data is generated by the alarm processing unit 58. Although not shown, a similar alarm device 60 may be installed in a location separate from the remote control LC.

[0055] The input data processing unit 57 processes the electric power load measurement value sent from the electric power load measuring means 16 and the thermal load measurement value sent from the thermal load measuring means 17, and provides the processed signals to the load calculation unit 51. Furthermore, the input data processing unit 57 is also connected to a remote control LC, and processes operation signals sent via the touch panel 64 of the remote control, and provides the processed signals to the operation control unit 54, etc., thereby enabling manual management and control of the fuel cell system.

[0056] The management center (management computer) 200 is configured with an operation merit function management unit 201 and a fuel cell operation information management unit 202. The management center 200 modifies the operation merit function based on fluctuations in various costs, etc. The operation merit function management unit 201 accesses the operation control device 100 in each user's home based on such modifications to the operation merit function, and updates the lookup table stored in the operation merit function storage unit 55. The fuel cell operation information management unit 202 records and manages the operation status (operation specifications, operating conditions, operation history, etc.) of the fuel cell system in each user's home.

[0057] Second Embodiment The fuel cell system of the second embodiment differs from the above-mentioned embodiments in the method of determining whether to operate or stop the operation. The fuel cell system of the second embodiment will be described below, but a description of the same configuration as the above-mentioned embodiments will be omitted.

[0058] Fig. 9 is a flowchart for explaining the determination of whether to operate or stop the operation of the solid oxide fuel cell 1, performed by the operation determination unit 53. Fig. 9 is the flowchart explained in Fig. 5 of the first embodiment, to which step #15 has been added.

[0059] In step #15, the operation determination unit 53 performs a cost verification process to determine whether the first operating cost when continuing to operate the solid oxide fuel cell 1 is greater than the second operating cost when starting up the solid oxide fuel cell 1 after stopping its operation. Specifically, the operation determination unit 53 performs a cost verification process to verify the first operating cost required when continuing to operate the solid oxide fuel cell 1 until the predicted power outage date and time within the power outage determination period when there is a high possibility of a power outage occurring during the power outage determination period, and the second operating cost required when stopping the operation of the solid oxide fuel cell 1 and then completing start-up of the solid oxide fuel cell 1 at the predicted power outage date and time.

[0060] Calculation of the first operating cost and the second operating cost will be described assuming, for example, that all of the load power of the power load unit 3 is covered by the power generated by the solid oxide fuel cell 1, and any surplus power is sold to the commercial power source 15. In this case, the operation determination unit 53 identifies the load power amount of the power load unit 3 during a period in the past (e.g., one month) when the solid oxide fuel cell 1 was operated, the power generated during that period, and the power sold to the commercial power source 15 during that period. Then, the operation determination unit 53 calculates, during that period, "gas cost required for operation" - "electricity cost for the amount of power sold" - "electricity cost assuming that (load power amount - amount of power sold) was purchased." In other words, the value (total cost) is calculated by subtracting the profit from selling power and the profit from not purchasing power from the cost required to operate the solid oxide fuel cell 1. The operation determination unit 53 calculates the cost per hour of operation by dividing the calculated total cost by the period (hours) during which operation was performed. Then, the operation determination unit 53 multiplies the calculated cost per hour of operation by the total time from the present time to the predicted power outage date and time to determine the first operating cost required to continue operating the solid oxide fuel cell 1 until the predicted power outage date and time.

[0061] In addition, the operation determination unit 53 calculates the sum of the shutdown cost (electricity and gas costs) required to stop operation of the solid oxide fuel cell 1 at the current time and the startup cost (electricity and gas costs) required to complete startup of the solid oxide fuel cell 1 at the predicted power outage date and time after continuing the shutdown, and sets this as the second operating cost.

[0062] Then, in step #15, if the first operating cost is greater than the second operating cost, the operation determination unit 53 proceeds to step #17 and outputs a determination result that operation should be stopped to the operation control unit 54. In this case, the operation control unit 54 stops the operation of the solid oxide fuel cell 1, and then completes the start-up of the solid oxide fuel cell 1 by the predicted power outage date and time. On the other hand, in step #15, if the first operating cost is not greater than the second operating cost, the operation determination unit 53 outputs a determination result to the operation control unit 54 that the process should proceed to step #16 and operation should be performed. Then, the operation control unit 54 outputs an operation execution command or an operation stop command to the solid oxide fuel cell 1 based on the determination result of the operation determination unit 53.

[0063] <Third embodiment> The fuel cell system of the third embodiment differs from the above-described embodiments in the method of determining whether to operate or stop the operation. The fuel cell system of the third embodiment will be described below, but a description of the same configuration as the above-described embodiments will be omitted.

[0064] FIG. 10 is a flowchart illustrating the determination made by the operation determination unit 53 as to whether to operate or stop the solid oxide fuel cell 1. In step #20, the operation determination unit 53 determines whether it is the timing for operation determination, that is, whether it is the day to determine whether operation / stop is to be performed. For example, if the timing for this operation determination is set to once a month at the end of the month, and the operation determination unit 53 determines using the calendar function that the current time is the end of the month (determined as "Yes" in step #20), it proceeds to step #21. On the other hand, if the operation determination unit 53 determines using the calendar function that the current time is not the end of the month (determined as "No" in step #20), it repeats the determination in step #20.

[0065] In step #21, the operation determination unit 53 performs a power outage possibility determination process, and if a planned power outage date and time exists within a future power outage determination period, it determines that there is a high possibility of a power outage occurring during that power outage determination period, and if there is no planned power outage date and time within the future power outage determination period, it determines that there is a low possibility of a power outage occurring during that power outage determination period.Then, in step #22, if the operation determination unit 53 determines that there is a high possibility of a power outage occurring, it proceeds to step #25, and if it determines that there is a low possibility of a power outage occurring, it proceeds to step #23.

[0066] In step #23, the driving determination unit 53 performs the driving possibility determination process similar to that described above with reference to FIGS.

[0067] Next, in step #24, if the result of the provisional judgment of the operation feasibility judgment process is that operation is stopped, the operation judgment unit 53 proceeds to step #26, and if the result of the provisional judgment of the operation feasibility judgment process is that operation is to be performed, the operation judgment unit 53 proceeds to step #25.

[0068] In step #25, the operation determination unit 53 outputs a determination result that operation should be performed to the operation control unit 54. In step #26, the operation determination unit 53 outputs a determination result that operation should be stopped to the operation control unit 54. Then, the operation control unit 54 outputs an operation execution command or an operation stop command to the solid oxide fuel cell 1 based on the determination result of the operation determination unit 53.

[0069] In this way, in this embodiment, the operation control unit 54 is configured to issue an operation execution command to the solid oxide fuel cell 1 if the power outage possibility determination process determines that there is a high possibility of a power outage, regardless of the result of the operation feasibility determination process; if the power outage possibility determination process determines that there is a low possibility of a power outage, issue an operation execution command to the solid oxide fuel cell 1 if the operation feasibility determination process provisionally determines that operation should be carried out; and issue an operation stop command to the solid oxide fuel cell 1 if the operation feasibility determination process provisionally determines that operation should be stopped.

[0070] <Another embodiment> <1> In the above embodiment, a specific example of the configuration of the fuel cell system has been described, but the configuration can be changed as appropriate.

[0071] <2> In the above embodiment, the operation possibility determination process and the power outage possibility determination process have been described using specific examples, but the content of these processes can be changed as appropriate.

[0072] <3> In the above embodiment, the operation feasibility determination process and power outage possibility determination process were explained focusing mainly on the power load of the power load section 3 as the energy load section L, but the operation feasibility determination process and power outage possibility determination process may also take into account the thermal load of the thermal load section 4 as the energy load section L.

[0073] <4> In the second embodiment described above, the operation determination unit 53 outputs a determination result indicating that operation should be stopped to the operation control unit 54 when the first operating cost is greater than the second operating cost (steps #15 and #17 in FIG. 9), and the operation control unit 54 stops the operation of the solid oxide fuel cell 1 and then completes the start-up of the solid oxide fuel cell 1 by the predicted power outage date and time. However, if the period from the present time to the predicted power outage date and time is short, there may be cases where it is difficult in time to stop the operation of the solid oxide fuel cell 1 during that time and then complete the start-up of the solid oxide fuel cell 1 by the predicted power outage date and time. Taking such cases into consideration, even if the operation determination unit 53 determines that the first operating cost is greater than the second operating cost in step #15 of Figure 9 (i.e., even if it is preferable from a cost perspective to stop operation of the solid oxide fuel cell 1), if the period from the present time to the predicted power outage date and time is shorter than the period required to complete startup of the solid oxide fuel cell 1 after stopping the power generation operation of the solid oxide fuel cell 1, it may output a determination result to the operation control unit 54 that the solid oxide fuel cell 1 should be operated (continue to operate).

[0074] <5> The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0075] The present invention can be used in a fuel cell system that can start and stop operation of a solid oxide fuel cell at appropriate times while taking into consideration how to respond to future power outages. [Explanation of symbols]

[0076] 1:Solid oxide fuel cell 2: Hot water tank 3: Power load section (energy load section L) 4: Heat load section (energy load section L) 16: Power load measuring means (load measuring unit S) 17: Heat load measurement means (load measurement unit S) 51: Load calculation section 52: Threshold setting section 53: Driving judgment unit 54: Operation control unit S: Load measurement section

Claims

1. A fuel cell system that supplies energy generated from a solid oxide fuel cell that can be selectively controlled to operate or stop operation to an energy load unit, a load measuring unit that measures load energy required by the energy load unit; a load calculation unit that calculates an average calculation value of the load measurement values ​​of the load measurement unit measured over a predetermined determination period; an operation determination unit that outputs a determination result that the solid oxide fuel cell should be operated or stopped based on the result of an operation feasibility determination process that makes a provisional determination that the solid oxide fuel cell should be operated or stopped based on the average calculation value or a substitute value derived from the average calculation value and a determination threshold value, the result of a power outage possibility determination process that determines the degree of possibility of a power outage occurring in a future power outage determination period, and the result of a cost verification process that verifies a first operating cost that will be required to continue operating the solid oxide fuel cell until a predicted power outage date and time within the power outage determination period if a power outage is likely to occur in the power outage determination period, and a second operating cost that will be required to complete start-up of the solid oxide fuel cell at the predicted power outage date and time after the operation of the solid oxide fuel cell is stopped; a threshold value setting unit that sets the determination threshold value; an operation control unit that issues an operation execution command or an operation stop command to the solid oxide fuel cell based on the determination result output by the operation determination unit, The operation determination unit outputs the determination result that operation of the solid oxide fuel cell should be stopped if the operation feasibility determination process provisionally determines that operation should be stopped, the power outage possibility determination process determines that there is a high possibility of a power outage, and the cost verification process determines that the first operating cost is greater than the second operating cost.

2. A fuel cell system as described in claim 1, wherein the operation determination unit outputs the determination result that the solid oxide fuel cell should be operated when the operation feasibility determination process provisionally determines that operation should be stopped, the power outage possibility determination process determines that there is a high possibility of a power outage, and the cost verification process determines that the first operating cost is not greater than the second operating cost.

3. 3. The fuel cell system according to claim 1, wherein the operation control unit outputs the determination result that the solid oxide fuel cell should be operated when it is provisionally determined in the operation feasibility determination process that operation should be performed.

4. The fuel cell system according to any one of claims 1 to 3, wherein the operation control unit outputs the determination result that the operation of the solid oxide fuel cell should be stopped when the operation feasibility determination process provisionally determines that operation should be stopped and the power outage possibility determination process determines that the possibility of a power outage is low.

5. The fuel cell system according to any one of claims 1 to 4, wherein the alternative value is a function value of an operating merit function that derives the operating merit of the solid oxide fuel cell from the average calculated value, and the threshold setting unit sets a judgment threshold converted into the operating merit as a merit judgment threshold.

6. 6. The fuel cell system according to claim 5, wherein the operational benefit is a reduction in primary energy consumption, a reduction in energy costs, or a reduction in carbon dioxide emissions obtained by operating the solid oxide fuel cell, or a combination thereof.

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