Power supply system and fuel cell device

Abstract

To provide a power supply system which consumes generated power by itself as much as possible and can suppress generation of power purchase as much as possible.SOLUTION: The power supply system includes a solar battery device 12 and a power generator 13 connected to a power line 11 coordinated with a power system 1, and also includes a predicted power generation derivation device 2 for deriving the shift of the predicted lower limit of the power generation predicted for the power generation of the solar battery device 12. The power generator 13 performs a power generation adjustment operation of adjusting the power generation of the power generator 13 so that the sum of the power generation of the power generator 13 and the predicted lower power generation derived by the predicted power generation derivation device 2 will comfort with the load power of a power load device 14 connected to the power line 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power supply system including a solar cell device and a power generation device that are connected to a power line that is linked to a power grid, and a fuel cell device. [Background technology]

[0002] In some power supply systems, facilities such as residences and offices are equipped with solar cell devices and power generation devices such as fuel cells. In such power supply systems, when power generation is performed simultaneously by the solar cell device and the power generation device, the total power generated by these devices may be greater than the load power of the power load devices installed in the facility. In other words, part of the generated power is not used within the facility, but flows back to the power grid outside the facility. Even in such cases, if power generation control is performed to keep the power generated by the power generation device such as a fuel cell low, the power generated by the solar cell device can be fully consumed by the facility.

[0003] Patent Document 1 (JP Patent Publication No. 2021-158809) describes a power supply system that aims to improve the self-consumption of power generated by a solar cell device. Specifically, in the invention described in Patent Document 1, the load power and the power generated by the solar cell device are predicted on the previous day, and the surplus power (= power generated by the solar cell device - load power) on the next day is predicted, and it is determined whether there is a time period in which the surplus power > β. If there is a time period in which the surplus power > β, a power generation request instruction is issued to the fuel cell during a time period in which no surplus power is generated and the amount of purchased power is predicted to be large. As a result, the fuel cell generates power during the time period in which the power generation request instruction is received on the next day, and stops generating power during the time period in which the power generation request instruction is not received. For example, in the period "from 8:00 to 18:00 on the second day" shown in FIG. 5 described in Patent Document 1, the fuel cell stops generating power, and the power demand is met by the power generated by the solar cell device. In addition, when the fuel cell generates power, as shown in FIG. 5 of Patent Document 1, a load-following operation is performed so that the power generated by the fuel cell is equal to the power demand. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-158809 Summary of the Invention [Problem to be solved by the invention]

[0005] In the power supply system described in Patent Document 1, the time period when the power generation of the solar cell device is predicted to be high is determined in advance as the time period when the fuel cell will stop generating power at the prediction stage of the previous day. In other words, the power supply system described in Patent Document 1 has the problem that the fuel cell is not fully utilized during the time period when the solar cell device is generating power during the day.

[0006] Furthermore, even if the power generation of the solar cell device is predicted to be large, if the sun is obscured by clouds on the day, the actual power generation of the solar cell device will drop significantly. Therefore, if the fuel cell stops generating power as described in Patent Document 1, the power generated within the facility cannot cover the load power, and there is a problem that a large amount of power will have to be purchased from the power grid.

[0007] Furthermore, in the power supply system described in Patent Document 1, when the fuel cell generates power, a load-following operation is performed so that the power generated by the fuel cell is equal to the power demand, as shown in Figure 5 of Patent Document 1. Therefore, if the time period when the solar cell device is generating power and the time period when the fuel cell is generating power overlap, the total power generated by these will greatly exceed the power demand, and there is a problem that the excess power cannot be self-consumed.

[0008] In order to reduce the reverse flow power to the power grid and the power purchased from the power grid, it is also possible to measure the power generated by the solar cell device or the power receiving point power of the facility and perform power generation control such as increasing or decreasing the power generated by the fuel cell according to the measurement results. However, there is a problem that the cost of installing equipment to measure the power generated by the solar cell device or the power receiving point power of the facility is high.

[0009] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a power supply system and a fuel cell device that can consume as much generated power as possible in-house and minimize the amount of power purchased from the power grid. [Means for solving the problem]

[0010] A characteristic configuration of a power supply system according to the present invention for achieving the above object is a power supply system including a solar cell device and a power generation device connected to a power line that is linked to a power grid, a predicted power generation deriving device that derives a transition of a predicted lower limit power generation power predicted for the power generation power of the solar cell device, The power generation device performs a power generation adjustment operation in which the power generation power of the power generation device is adjusted so that the sum of the power generation power of the power generation device and the predicted lower limit power generation power derived by the predicted power generation derivation device tracks the load power of a power load device connected to the power line.

[0011] According to the above characteristic configuration, even if the power generated by the solar cell device decreases due to clouds obscuring the sun, the load power of the power load device is expected to be covered by the power generated by the power generation device and the power generated by the solar cell device. In other words, even if the power generated by the solar cell device decreases due to clouds obscuring the sun, the generation of purchased power from the power grid is suppressed. When the sun is not in the shade and the power generated by the solar cell device is sufficiently large, the sum of the power generated by the power generation device and the power generated by the solar cell device becomes larger than the load power of the power load device, and the surplus power flows back to the power grid. However, in this characteristic configuration, the power generated by the power generation device is adjusted to be smaller than the load power of the power load device, so even if surplus power as described above occurs, its magnitude is kept small. In other words, the power generated by the power generation device and the power generated by the solar cell device are consumed in-house as much as possible. Therefore, it is possible to provide a power supply system that can self-consume as much of the generated power as possible and minimize the amount of power purchased from the power grid.

[0012] Another characteristic configuration of the power supply system of the present invention is that the predicted power generation derivation device derives the trend of the predicted lower limit power generation by referring to the trend of the lower limit solar radiation, which is the lower limit of the confidence interval set for the predicted value of solar radiation at the location where the solar cell device is installed.

[0013] According to the above characteristic configuration, by referring to the trend of the lower limit solar radiation, which is the lower limit of the confidence interval set for the predicted value of solar radiation at the location where the solar cell device is installed, it is possible to derive a highly reliable trend of the predicted lower limit power generation power.

[0014] Another characteristic configuration of the power supply system of the present invention is that the predicted power generation derivation device derives the predicted lower limit power generation power by multiplying the rated power generation power of the solar cell device by a first output coefficient that can be used to derive a predicted maximum power generation power that is predicted to be able to be generated by the solar cell device at a target date and time, and a second output coefficient that is expressed as a function of the lower limit solar radiation and can be used to derive the predicted lower limit power generation power that is predicted to be able to be generated by the solar cell device at a target date and time, based on the first output coefficient and the second output coefficient.

[0015] According to the above characteristic configuration, by multiplying the rated power generation of the solar cell device by the first output coefficient, it is possible to derive a predicted maximum power generation power that is predicted to be generated by the solar cell device at the target date and time, and by multiplying the predicted maximum power generation power by the second output coefficient, it is possible to derive a predicted lower limit power generation power that is predicted to be generated by the solar cell device at the target date and time.

[0016] Another characteristic configuration of the power supply system of the present invention is that the predicted power generation derivation device derives the predicted lower limit power generation power by multiplying the rated power generation power of the solar cell device by a first output coefficient that can be used to derive a predicted maximum power generation power that is predicted to be generated by the solar cell device at a target date and time, and a third output coefficient that is a ratio of a first predicted amount of solar radiation, which is a predicted value of solar radiation on a clear day at the location where the solar cell device is installed, to a second predicted amount of solar radiation, which is a predicted amount of solar radiation based on image information that can estimate the amount of cloud cover at the location where the solar cell device is installed.

[0017] According to the above characteristic configuration, by multiplying the rated power generation of the solar cell device by the first output coefficient, it is possible to derive a predicted maximum power generation power that is predicted to be able to generate by the solar cell device at the target date and time, and by multiplying that predicted maximum power generation power by the third output coefficient, which is the ratio of the second predicted solar radiation, which is the amount of solar radiation predicted based on image information that can estimate the amount of cloud cover at the location where the solar cell device is installed, to the first predicted solar radiation, which is the predicted value of the amount of solar radiation on a clear day at the location where the solar cell device is installed, it is possible to derive a predicted lower limit power generation power that is predicted to be able to generate by the solar cell device at the target date and time.

[0018] Another characteristic configuration of the power supply system according to the present invention is that the predicted generated power deriving device comprises: Collecting solar radiation data consisting of extraterrestrial solar radiation, predicted values ​​of solar radiation, and actual measured values ​​of solar radiation at each of a plurality of past times; Deriving a first ratio, which is a ratio of a predicted value of the amount of solar radiation to the amount of extraterrestrial solar radiation, and a second ratio, which is a ratio of an actual value of the amount of solar radiation to the amount of extraterrestrial solar radiation, for each time of the solar radiation data; The solar radiation data is classified into one of a plurality of numerical ranges set for the first ratio; deriving a third ratio, which is a ratio of the second ratio to the first ratio for each of the solar radiation amount data belonging to each of the plurality of numerical ranges; The third ratio, in which the cumulative value of the existence ratio when the third ratios of each of the solar radiation amount data belonging to the numerical range are accumulated in ascending order from the smallest, is set to a predetermined value from the smallest as a conversion ratio from the predicted value of the solar radiation amount corresponding to the numerical range; when the predicted value of the amount of solar radiation and the predicted value of extra-atmospheric solar radiation at a location where the solar cell device is installed at a target date and time are obtained, a ratio of the predicted value of the amount of solar radiation to the predicted value of the extra-atmospheric solar radiation is determined to which of the plurality of numerical ranges set for the first ratio belongs, and a product of the predicted value of the amount of solar radiation and the conversion ratio set in the determined numerical range is derived as an estimated value of solar radiation obtained at least at the location where the solar cell device is installed; The transition of the predicted lower limit power generation power is derived based on the transition of the estimated value of the amount of solar radiation.

[0019] Even if a predicted value of the amount of solar radiation is obtained from a weather forecast service or the like, the amount of solar radiation changes depending on the actual weather. However, by referring to the predicted value of the amount of solar radiation in the past and the actual measured value of the amount of solar radiation, it is possible to estimate with a certain degree of probability what amount of solar radiation can be obtained. For example, it is possible to derive a predetermined conversion ratio, and derive the product of the predicted value of the amount of solar radiation and the conversion ratio as an estimated value of the amount of solar radiation that can be estimated to be obtained at least. Then, it is also possible to derive the above-mentioned predicted lower limit power generation power based on the estimated value of the amount of solar radiation. Therefore, in this characteristic configuration, for each of a plurality of numerical ranges, the third ratio of the solar radiation data belonging to each numerical range is accumulated in ascending order, and the third ratio that has a cumulative value of the existence ratio that is a predetermined value from the smallest is set as the conversion ratio from the predicted value of the solar radiation corresponding to the numerical range. Here, the third ratio is the second ratio (the actual measured value of the solar radiation to the extraterrestrial solar radiation) to the first ratio (the predicted value of the solar radiation to the extraterrestrial solar radiation), so the third ratio corresponds to the ratio of the actual measured value of the solar radiation to the predicted value of the solar radiation. Therefore, when the predicted value of the solar radiation is determined, it is expected that at least the solar radiation (estimated value of the solar radiation) that is the product of the predicted value of the solar radiation and the above conversion ratio can be probabilistically obtained. Then, the transition of the predicted lower limit power generation power can be derived based on the transition of the estimated value of the solar radiation.

[0020] A characteristic feature of the fuel cell device according to the present invention for achieving the above object is that it has the function of the power generation device used in the above power supply system, and generates both heat and electricity.

[0021] According to the above characteristic configuration, it is possible to provide a fuel cell device having the function of a power generation device used in a power supply system that can self-consume as much generated power as possible and minimize the generation of purchased power from the power grid.

[0022] Another characteristic configuration of the fuel cell device according to the present invention is that when a command to perform the power generation adjustment operation is received from an external server device, If a predetermined heat utilization condition is satisfied, which indicates that the generated heat is in a state where it can be utilized, the power generation adjustment operation is not performed; If the heat utilization condition is not satisfied, the power generation adjustment operation is performed.

[0023] When power generation adjustment operation is performed, the power generated by the fuel cell device becomes smaller than the load power of the power load device. In other words, when power generation adjustment operation is performed, it means that less heat is generated by the fuel cell device. Therefore, when the heat utilization condition is satisfied (i.e., when most of the generated heat is utilized), the amount of heat generated by the fuel cell device decreases when power generation adjustment operation is performed, and the operating costs of, for example, a heat source device to generate the reduced amount of heat increase. However, in this characteristic configuration, the fuel cell device does not perform power generation adjustment operation when the heat utilization conditions are satisfied, so that an increase in the operating costs of the heat source device as described above can be suppressed.

[0024] Another characteristic configuration of the fuel cell device of the present invention is that when it receives a command to perform the power generation adjustment operation from an external server device, if certain heat utilization conditions, which indicate that the generated heat is in a situation where it can be utilized, continue for a predetermined period of time or more, the power generation adjustment operation is not performed, and if the heat utilization conditions do not continue for a predetermined period of time or more, the power generation adjustment operation is performed.

[0025] When power generation adjustment operation is performed, the generated power of the fuel cell device becomes smaller than the load power of the power load device. In other words, when power generation adjustment operation is performed, it means that the heat generated by the fuel cell device decreases. Therefore, when the state in which the heat utilization condition is satisfied continues for a predetermined period or more (i.e., when the state in which most of the generated heat is utilized continues for a predetermined period or more), the amount of heat generated by the fuel cell device decreases when power generation adjustment operation is performed, and the operating cost of, for example, a heat source device to generate the reduced amount of heat increases. However, with this characteristic configuration, the fuel cell device does not perform power generation adjustment operation if the heat utilization conditions are satisfied for a predetermined period of time or longer, thereby preventing an increase in operating costs for the heat source unit as described above.

[0026] Another characteristic configuration of the fuel cell device according to the present invention is to calculate a cost of electricity per unit energy when the generated power of the solar cell device is sold to the power grid, a first cost per unit energy required to generate heat and electricity when the generated heat is utilized, and a second cost per unit energy required to generate heat and electricity when the generated heat is not utilized, based on a comparison result between the selling price per unit energy when the generated power of the solar cell device is sold to the power grid, When the first cost unit price and the second cost unit price are greater than the power selling price, the power generation adjustment operation is performed upon receiving a command to perform the power generation adjustment operation from an external server device; When the first cost unit price is smaller than the power selling price and the second cost unit price is larger than the power selling price, when a command to perform the power generation adjustment operation is received from an external server device, if a predetermined heat utilization condition indicating that the generated heat is in a state where it can be utilized is not satisfied, the power generation adjustment operation is performed, and if the heat utilization condition is satisfied, the power generation adjustment operation is not performed; When the first cost unit price and the second cost unit price are smaller than the power selling price, the power generation adjustment operation is not performed even if a command to perform the power generation adjustment operation is received from an external server device.

[0027] When power generation adjustment operation is performed, the power generated by the fuel cell device becomes smaller than the load power of the power load device, so it is considered that the power generated by the solar cell device that is reverse-flowed to the power grid (i.e., power to be sold) will decrease. Therefore, when power generation adjustment operation is performed, the profit that can be calculated using the power selling price will decrease. In addition, when power generation adjustment operation is performed, that is, the power generated by the fuel cell device becomes smaller, it is considered that the cost that can be calculated using the first cost unit price per unit energy required to generate heat and electricity when the generated heat is utilized will decrease, and the cost that can be calculated using the second cost unit price per unit energy required to generate heat and electricity when the generated heat is not utilized will decrease. Therefore, in this characteristic configuration, when the first cost unit price and the second cost unit price are greater than the power selling price, the power generation adjustment operation is performed upon receiving a command to perform the power generation adjustment operation from the external server device. This makes it possible to make the reduction in costs caused by reducing the power generation of the fuel cell device exceed the reduction in profits caused by reducing the power sold from the power generation of the solar cell device when the power generation adjustment operation is performed. Furthermore, when the first cost unit price is smaller than the power selling price and the second cost unit price is larger than the power selling price, when a command to perform power generation adjustment operation is received from an external server device, if a predetermined heat utilization condition indicating that the generated heat is being utilized is not satisfied, the power generation adjustment operation is performed, and if the heat utilization condition is satisfied, the power generation adjustment operation is not performed. This makes it possible to ensure that when the power generation adjustment operation is performed, the reduction in costs due to the reduction in the power generated by the fuel cell device exceeds the reduction in profits due to the reduction in the power sold by the solar cell device. Furthermore, it is possible to ensure that when the power generation adjustment operation is performed, the reduction in profits due to the reduction in the power sold by the solar cell device does not exceed the reduction in costs due to the reduction in the power generated by the fuel cell device. Furthermore, when the first cost unit price and the second cost unit price are smaller than the power selling price, the power generation adjustment operation is not performed even if a command to perform the power generation adjustment operation is received from the external server device. This makes it possible to ensure that the reduction in profits caused by the reduction in the power sold of the power generated by the solar cell device when the power generation adjustment operation is performed does not exceed the reduction in costs caused by the reduction in the power generated by the fuel cell device. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a power supply system. [Diagram 2] 13 is a flowchart illustrating a process for deriving a predicted lower limit power generation power of a solar cell device. [Diagram 3] FIG. 4 is a diagram illustrating the transition of power generation by the solar cell device. [Figure 4] 4 is a flowchart illustrating power generation control of the power generation device. [Diagram 5]13 is a flowchart illustrating a process for deriving a predicted lower limit power generation power of a solar cell device. [Figure 6] 1 is a graph showing the results of an analysis of past extraterrestrial radiation, predicted values ​​of radiation, and actual measured values ​​of radiation. [Figure 7] 13 is a graph showing accumulated values ​​of the presence ratios when solar radiation amount data belonging to the same numerical range are accumulated in ascending order of third ratios. [Figure 8] FIG. 1 is a diagram illustrating a configuration of a power supply system. [Figure 9] This figure shows the results of a comparison between the selling price of electricity from a solar cell device, the first cost unit price (with heat utilization) when it is assumed that the generated heat is utilized, and the second cost unit price (without heat utilization) when it is assumed that the generated heat is not utilized. [Figure 10] This figure shows the results of a comparison between the selling price of electricity from a solar cell device, the first cost unit price (with heat utilization) when it is assumed that the generated heat is utilized, and the second cost unit price (without heat utilization) when it is assumed that the generated heat is not utilized. [Figure 11] This figure shows the results of a comparison between the selling price of electricity from a solar cell device, the first cost unit price (with heat utilization) when it is assumed that the generated heat is utilized, and the second cost unit price (without heat utilization) when it is assumed that the generated heat is not utilized. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] First Embodiment A power supply system according to a first embodiment of the present invention will be described below with reference to the drawings. As shown in the figure, the power supply system includes a solar cell device 12 and a power generation device 13 connected to a power line 11 that is linked to a power system 1. In the example shown in Fig. 1, the solar cell device 12 and the power generation device 13 are installed in a facility 10 such as a residence or a business office. In addition, a power load device 14 is also connected to the power line 11 of the facility 10. As a result, the power load device 14 can receive power supply from at least one of the solar cell device 12, the power generation device 13, and the power system 1.

[0030] The power generating device 13 is a device equipped with a fuel cell, a device equipped with an engine and a generator driven by the engine, etc. The power generating device 13 can adjust the generated power between a predetermined minimum generated power or more and a maximum generated power or less (e.g., rated generated power, etc.).

[0031] The power generation device 13 can recognize the value of the load power of the power load device 14. For example, a power measurement unit 15 is provided on the power line 11, and the measurement result is transmitted to the power generation device 13. The power measured by the power measurement unit 15 is the power supplied to the power load device 14 from at least one of the power system 1 and the solar cell device 12. The power generation device 13 can also recognize the power it supplies to the power line 11 (i.e., the generated power). As a result, the power generation device 13 can recognize the sum of the power measured by the power measurement unit 15 and its own generated power as the load power of the power load device 14.

[0032] In addition, the power supply system includes a predicted power generation power deriving device 2 that derives a transition of a predicted lower limit power generation power predicted for the power generation power of the solar cell device 12. Fig. 1 shows an example in which the predicted power generation power deriving device 2 is installed outside the facility 10. In this case, the power generation device 13 and the predicted power generation power deriving device 2 are capable of communicating information with each other via an information communication line 5. For example, the predicted power generation power deriving device 2 can be realized by using a server device.

[0033] 1, the predicted power generation power deriving device 2 can read information stored in a storage device 3 and write information to the storage device 3. Furthermore, the predicted power generation power deriving device 2 can receive information from an information providing server device 4 connected via an information communication line 5.

[0034] For example, the predicted power generation derivation device 2 can receive information on the predicted value of the amount of solar radiation at the location where the solar cell device 12 is installed at the target date and time (solar radiation information) from the information providing server device 4, and store it in the storage device 3. This solar radiation information also includes information on the confidence interval of the predicted value of the amount of solar radiation at the target date and time, i.e., the upper and lower limits of the predicted amount of solar radiation. For example, the lower limit of the numerical range in which the reliability probability of the amount of solar radiation is 90% may be set as the lower limit of the amount of solar radiation, but the reliability probability in this case can be changed as appropriate. In other words, even if the sun is obscured by clouds or the like, the amount of solar radiation at the target date and time is predicted to be equal to or greater than the lower limit. On the other hand, the upper limit of the predicted amount of solar radiation corresponds to the predicted value of the amount of solar radiation on a clear day (first predicted amount of solar radiation to be described later).

[0035] In addition, the predicted power generation deriving device 2 can receive image information (e.g., satellite images, images of the sky around the installation location of the solar cell device 12 taken from the ground, etc.) capable of estimating the amount of cloud cover at the location where the solar cell device 12 is installed from the information providing server device 4, and store the information in the storage device 3. In this case, the predicted power generation deriving device 2 can determine, based on the image information, a second predicted amount of solar radiation, which is the amount of solar radiation predicted at the location where the solar cell device 12 is installed at the time when the image information is acquired or after a set time period thereafter.

[0036] Alternatively, the predicted power generation deriving device 2 may receive information on the second predicted amount of solar radiation predicted based on image information capable of estimating the amount of cloud cover at the location where the solar cell device 12 is installed from the information providing server device 4. For example, the predicted power generation deriving device 2 may determine the second predicted amount of solar radiation at a target time point (for example, the current date and time) by using information provided by SOLASAT (registered trademark), a solar radiation estimation and prediction service based on image information provided by the Japan Weather Association (i.e., information provided by the information providing server device 4).

[0037] The storage device 3 stores information on the rated power generation of the solar cell device 12, a first output coefficient, and a second output coefficient.

[0038] The first output coefficient is a value determined according to the relative positional relationship between the solar panel of the solar cell device 12 and the sun (for example, the installation direction and installation angle of the solar cell panel). Therefore, the first output coefficient has a different value depending on the date and time (i.e., a value that changes over time). Then, by multiplying the rated power generation of the solar cell device 12 by the first output coefficient at a target date and time, it is possible to derive a predicted maximum power generation that the solar cell device 12 is predicted to be able to generate at the target date and time. Furthermore, by using information on the first output coefficient that changes over time, it is possible to derive the change in the predicted maximum power generation.

[0039] The second output coefficient is expressed as a function of the lower limit solar radiation, which is the lower limit of a confidence interval set for the predicted value of solar radiation at the location where the solar cell device 12 is installed, and is multiplied by the above-mentioned predicted maximum power generation power to derive the predicted lower limit power generation power that is predicted to be able to generate by the solar cell device 12 at the target date and time. Since the predicted value of solar radiation at the location where the solar cell device 12 is installed is a value that differs depending on the date and time, the lower limit solar radiation also becomes a value that differs depending on the date and time (i.e., a value that changes over time), and the second output coefficient also becomes a value that differs depending on the date and time (i.e., a value that changes over time).

[0040] 2 is a flowchart illustrating steps performed by the predicted power generation power deriving device 2 to derive the predicted lower limit power generation power of the solar cell device 12. In step #10, the predicted power generation power deriving device 2 reads out the rated power generation power of the solar cell device 12 stored in the storage device 3.

[0041] In step #11, the predicted power generation power deriving device 2 reads out the first output coefficient stored in the storage device 3. This first output coefficient has a different value depending on the date and time. For example, the predicted power generation power deriving device 2 reads out information from the storage device 3 that indicates the temporal change in the first output coefficient for one day.

[0042] It should be noted that the way in which the date and time are divided can be set appropriately. A year may be divided into four seasons, and the days in each season may be further divided into 30-minute intervals, and the first output coefficient for each 30-minute interval of each day in a particular season of the year may be determined. The seasons may be divided, for example, into spring (March to May), summer (June to August), autumn (September to November), and winter (December to February). In this case, the first output coefficient for each 30-minute interval of each day will be the same value if it is the same season.

[0043] Alternatively, a year may be divided into 12 months, and each day of each month may be divided into 30-minute intervals, and the first output coefficient for each 30-minute interval for each day in a specific month of the year may be determined. In this case, the first output coefficients for each 30-minute interval for each day in the same month will be the same value.

[0044] Alternatively, a year may be divided into 365 days, and each day may be further divided into 30-minute intervals, and the first output coefficient may be determined for each 30-minute interval on a specific day of the year. In this case, the first output coefficient for each 30-minute interval on each day is determined separately for each of the 365 days of the year.

[0045] In step #12, the predicted power generation power deriving device 2 receives information on the lower limit solar radiation from the information providing server device 4. This lower limit solar radiation is the lower limit of the confidence interval of the predicted value of the solar radiation at the location where the solar cell device 12 is installed at the target date and time. The width of the confidence interval can be set appropriately, and for example, the lower limit solar radiation may be the lower limit of a numerical range in which the reliability probability of the solar radiation is 90%. Furthermore, similar to the case of the first output coefficient described above, the predicted power generation power deriving device 2 may receive information from the information providing server device 4 showing the temporal change of the lower limit solar radiation over one day.

[0046] In step #13, the predicted power generation derivation device 2 derives a second output coefficient based on the lower limit solar radiation received in step #12. Similarly to the above-mentioned first output coefficient, the second output coefficient is a value determined for each target date and time. For example, the predicted power generation derivation device 2 derives information showing the temporal change of the second output coefficient for one day.

[0047] In step #14, the predicted power generation derivation device 2 derives the predicted lower-limit power generation power by multiplying the rated power generation power by the first output coefficient and the second output coefficient. In other words, by multiplying the rated power generation power of the solar cell device 12 by the first output coefficient, it is possible to derive the predicted maximum power generation power that is predicted to be able to be generated by the solar cell device 12 at the target date and time, and by multiplying the predicted maximum power generation power by the second output coefficient, it is possible to derive the predicted lower-limit power generation power that is predicted to be able to be generated by the solar cell device 12 at the target date and time. Then, the predicted power generation derivation device 2 transmits information about the derived predicted lower-limit power generation power at the target date and time to the power generation device 13. For example, the predicted power generation deriving device 2 derives information on the previous day that indicates the time transition of the predicted lower limit power generation power for the next day, and transmits the information to the power generation device 13. Then, as described later, the power generation device 13 can adjust the power generation power for the day by using the information on the predicted lower limit power generation derived on the previous day.

[0048] In this way, when the predicted power generation derivation device 2 derives the predicted lower limit power generation, the lower limit solar radiation, which is the lower limit of the confidence interval set for the predicted value of solar radiation at the location where the solar cell device 12 is installed, is referenced, so that a highly reliable predicted lower limit power generation can be derived.

[0049] Fig. 3 is a diagram for explaining the transition of the actual power generation of the solar cell device 12. In Fig. 3, the solid line indicates the actual power generation of the solar cell device 12, the dashed line indicates the predicted maximum power generation derived as described above, and the dashed line indicates the predicted lower limit power generation derived as described above. As shown in the figure, the actual power generation of the solar cell device 12 occurs from about 7:00 to about 17:00.

[0050] As shown in the figure, the actual power generation of the solar cell device 12 is between the predicted lower limit power generation and the predicted maximum power generation. The actual power generation of the solar cell device 12 drops to a value close to the predicted lower limit power generation during times when the sun is obscured by clouds, etc. Information on the transition of the predicted lower limit power generation as shown in the figure is transmitted to the power generation device 13.

[0051] In the power supply system of this embodiment, the power generation device 13 performs a power generation adjustment operation to adjust the power generation of the power generation device 13 so that the sum of the power generation of the power generation device 13 and the predicted lower-limit power generation power derived by the predicted power generation derivation device 2 follows the load power of the power load device 14 connected to the power line 11. Here, the operation of the power generation device 13 in a state in which the sum of the power generation of the power generation device 13 and the predicted lower-limit power generation power follows the load power of the power load device 14 means, for example, an operation in which the sum of the power generation of the power generation device 13 and the predicted lower-limit power generation power is maintained equal to the load power of the power load device 14, an operation in which the sum of the power generation of the power generation device 13 and the predicted lower-limit power generation power is maintained greater than or less than the load power of the power load device 14 by a predetermined amount, and the like.

[0052] FIG. 4 is a flowchart illustrating power generation control of the power generation device 13. In step #20, the power generation device 13 sets the target power generation power such that "target power generation power = load power of power load device 14 - predicted lower limit power generation power". Here, the power generation device 13 recognizes the sum of the power measured by the power measurement unit 15 at that time and its own power generation at that time as the load power of the power load device 14 at that time. Then, the power generation device 13 determines the target power generation power at that time from the sum of the load power at that time and the predicted lower limit power generation power at that time.

[0053] Note that the power generation device 13 cannot accommodate any value of the target power generation, and can only adjust the power generation to a value between a predetermined minimum power generation power or more and a maximum power generation power or less (e.g., rated power generation power, etc.). Therefore, in steps #21 and #22, the power generation device 13 determines whether the target power generation derived in step #20 is equal to or more than the minimum power generation power and equal to or less than the maximum power generation power. If the target power generation derived in step #20 is equal to or more than the minimum power generation power and equal to or less than the maximum power generation power (i.e., if "Yes" in step #21 and "Yes" in step #22), the power generation device 13 proceeds to step #23 and adjusts the power generation to the target power generation derived in step #20.

[0054] On the other hand, if the target generated power derived in step #20 is smaller than the minimum generated power (i.e., if the answer is "No" in step #21), the power generation device 13 proceeds to step #24 and adjusts the generated power to the minimum generated power.

[0055] Furthermore, if the target power generation derived in step #20 is greater than the maximum power generation (i.e., if the answer is "Yes" in step #21 and "No" in step #22), the power generation device 13 proceeds to step #25 and adjusts the power generation to the maximum power generation.

[0056] Then, in step #26, the power generation device 13 adjusts the power generation power to the value determined in step #23, step #24, or step #25 and generates power for a certain period of time. After the certain period of time has elapsed, the power generation device 13 proceeds to step #20 and determines the power generation power again as described above. Since the certain period of time has elapsed, it is assumed that the predicted lower limit power generation power and the load power are different from the time when the power generation power was determined last time. Therefore, it is assumed that the target power generation derived in step #20 is also different from the value derived last time.

[0057] As described above, the power generation device 13 performs a power generation adjustment operation to adjust the power generation of the power generation device 13 so that the sum of the power generation of the power generation device 13 and the predicted lower limit power generation power derived by the predicted power generation derivation device 2 follows the load power of the power load device 14 connected to the power line 11. Therefore, even if the power generation of the solar cell device 12 decreases due to clouds obscuring the sun (for example, it decreases to the predicted lower limit power generation), it is expected that the load power of the power load device 14 will be covered by the power generation of the power generation device 13 and the power generation of the solar cell device 12. In other words, even if the power generation of the solar cell device 12 decreases due to clouds obscuring the sun, the generation of purchased power from the power grid 1 is suppressed. Note that when the sun is not obscured and the power generation of the solar cell device 12 is sufficiently large, the sum of the power generation of the power generation device 13 and the power generation of the solar cell device 12 becomes larger than the load power of the power load device 14, and the surplus power flows back to the power grid 1. However, in this embodiment, the power generated by the power generation device 13 is adjusted to be smaller than the load power of the power load device 14, so even if surplus power as described above occurs, its magnitude is kept small. In other words, the power generated by the power generation device 13 and the power generated by the solar cell device 12 are self-consumed as much as possible.

[0058] <Second embodiment> The power supply system of the second embodiment differs from the above-mentioned embodiment in the process of deriving the predicted lower limit generated power. The power supply system of the second embodiment will be described below, but the description of the same configuration as the above-mentioned embodiment will be omitted.

[0059] 5 is a flowchart explaining the process of deriving the predicted lower limit power generation power of the solar cell device 12. For example, on the day when the power generation power of the power generation device 13 is adjusted, the predicted power generation power deriving device 2 derives the predicted lower limit power generation power as described below at a set timing, for example, every 30 minutes, and transmits it to the power generation device 13. Then, the power generation device 13 can adjust the power generation power for that day using information on the derived predicted lower limit power generation power.

[0060] In step # 30 , the predicted generated power deriving device 2 reads out the rated generated power of the solar cell device 12 stored in the storage device 3 . In step #31, the predicted power generation power deriving device 2 reads out the first output coefficient at the target time point stored in the storage device 3. For example, the predicted power generation power deriving device 2 reads out the first output coefficient at the current date and time from the storage device 3.

[0061] In step #32, the predicted generated power deriving device 2 reads out from the storage device 3 a first predicted amount of insolation, which is a predicted value of the amount of insolation on a clear day at the location where the solar cell device 12 is installed at a target time point.

[0062] In step #33, the predicted power generation derivation device 2 determines a second predicted amount of solar radiation at the target time, which is a predicted amount of solar radiation based on image information (e.g., a satellite image, an image of the sky around the installation location of the solar cell device 12 taken from the ground, etc.) that can estimate the amount of cloud cover at the location where the solar cell device 12 is installed.

[0063] In step #34, the predicted power generation derivation device 2 derives a third output coefficient, which is the ratio of the second predicted amount of solar radiation, which is the amount of solar radiation predicted based on image information that can estimate the amount of cloud cover at the location where the solar cell device 12 is installed, to the first predicted amount of solar radiation, which is the predicted value of the amount of solar radiation on a clear day at the location where the solar cell device 12 is installed.

[0064] In step #35, the predicted power generation derivation device 2 derives the predicted lower limit power generation power by multiplying the rated power generation power by the first output coefficient and the third output coefficient based on the above-mentioned first output coefficient and third output coefficient. In this way, by multiplying the rated power generation power of the solar cell device 12 by the first output coefficient, the predicted maximum power generation power predicted to be generated by the solar cell device 12 at the target date and time can be derived, and by multiplying the predicted maximum power generation power by the third output coefficient, which is the ratio of the second predicted solar radiation, which is the solar radiation predicted based on image information that can estimate the cloud amount at the location where the solar cell device 12 is installed, to the first predicted solar radiation, which is the predicted value of the solar radiation on a clear day at the location where the solar cell device 12 is installed, the predicted lower limit power generation power predicted to be generated by the solar cell device 12 at the target date and time can be derived. Then, the predicted power generation derivation device 2 transmits information about the predicted lower limit power generation power at the target date and time that has been derived to the power generation device 13.

[0065] The power generation device 13 refers to the predicted lower limit power generation power derived by the predicted power generation derivation device 2 as described above, and determines the target power generation power at that time from the sum of the load power at that time and the predicted lower limit power generation power at that time, as in the first embodiment.

[0066] <Third embodiment> The power supply system of the third embodiment differs from the above-mentioned embodiments in the method of deriving the predicted lower limit generated power. The power supply system of the third embodiment will be described below, but the description of the same configuration as the above-mentioned embodiments will be omitted.

[0067] The predicted power generation derivation device 2 can receive information on the transition of the predicted value of the amount of solar radiation and the transition of the amount of extraterrestrial solar radiation at the location where the solar cell device 12 is installed at a target date and time from the information providing server device 4, and store the information in the storage device 3. In the above embodiment, an example was described in which the predicted lower-limit power generation power was derived using the lower limit value of the confidence interval set for the predicted value of the amount of solar radiation at the location where the solar cell device 12 is installed, but in the present embodiment, an example is described in which the predicted lower-limit power generation power is derived using a different method.

[0068] FIG. 6 is a graph showing the results of analyzing the amount of extraterrestrial solar radiation, the predicted value of solar radiation, and the actual value of solar radiation in the past. The predicted power generation derivation device 2 collects in advance solar radiation data consisting of the amount of extraterrestrial solar radiation, the predicted value of solar radiation, and the actual value of solar radiation at each of a plurality of times in the past. Then, for the solar radiation data, the predicted power generation derivation device 2 derives a first ratio, which is the ratio of the predicted value of solar radiation to the amount of extraterrestrial solar radiation, and a second ratio, which is the ratio of the actual value of solar radiation to the amount of extraterrestrial solar radiation, for each time. That is, here, the predicted value of solar radiation and the actual value of solar radiation are normalized by the amount of extraterrestrial solar radiation.

[0069] The horizontal axis of Figure 6 is the first ratio, which is the ratio of the predicted value of solar radiation to the amount of extraterrestrial solar radiation. Therefore, the fewer the clouds in the forecast, the larger the first ratio, and the more clouds in the forecast, the smaller the first ratio. In Figure 6, the first ratio is divided into multiple numerical ranges. For example, it is divided into six numerical ranges: numerical range A of "0<first ratio≦0.2", numerical range B of "0.2<first ratio≦0.3", numerical range C of "0.3<first ratio≦0.4", numerical range D of "0.4<first ratio≦0.5", numerical range E of "0.5<first ratio≦0.6", numerical range F of "0.6<first ratio≦0.7", and numerical range G of "0.7<first ratio≦1.0".

[0070] The vertical axis of Fig. 6 is the second ratio, which is the ratio of the actual measured value of the amount of solar radiation to the amount of solar radiation outside the atmosphere. That is, Fig. 6 plots the relationship between the first ratio, which is the ratio of the predicted value of the amount of solar radiation to the amount of solar radiation outside the atmosphere, and the second ratio, which is the ratio of the actual measured value of the amount of solar radiation to the amount of solar radiation outside the atmosphere, derived for each time from the collected solar radiation data. The predicted power generation derivation device 2 classifies the solar radiation data in a form in which the data belongs to one of a plurality of numerical ranges A to G set for the first ratio. Then, analysis is performed for each group of solar radiation data belonging to the same numerical range.

[0071] First, the predicted generated power deriving device 2 derives, for each of a plurality of numerical ranges, a third ratio which is the ratio of the second ratio to the first ratio for each of the solar radiation data belonging to the numerical range.

[0072] FIG. 7 is a graph showing the cumulative value of the existence ratio when the solar radiation amount data belonging to the same numerical range are accumulated in order from the smallest third ratio. Note that FIG. 7 does not show the solar radiation amount data of the numerical range A. For example, in the case of the numerical range G, the third ratio is about 0.50 when the cumulative value of the existence ratio of the solar radiation amount data is 20%. This means that the third ratio of 20% of the solar radiation amount data belonging to the numerical range G is about 0.50 or less. In other words, it means that the third ratio of 80% of the solar radiation amount data belonging to the numerical range G is greater than about 0.50. Therefore, the lower limit of the third ratio when 80% of the solar radiation amount data belonging to the numerical range G is covered is about 0.50.

[0073] Similarly, in the case of numerical range F, the third ratio is 0.31 when the cumulative value of the proportion of solar radiation data present is 20%. This means that the third ratio of 20% of the solar radiation data belonging to numerical range F is less than or equal to 0.31. In other words, this means that the third ratio of 80% of the solar radiation data belonging to numerical range F is greater than 0.31. Therefore, the lower limit of the third ratio when 80% of the solar radiation data belonging to numerical range G is covered is 0.31.

[0074] Here, the third ratio is the ratio of the second ratio to the first ratio, i.e., the actual measured value of solar radiation normalized by extraterrestrial solar radiation to the predicted value of solar radiation normalized by extraterrestrial solar radiation. Therefore, it can be said that the third ratio indicates the ratio of the actual measured value of solar radiation to the predicted value of solar radiation (=actual measured value of solar radiation / predicted value of solar radiation). Therefore, in the case of solar radiation data belonging to the numerical range G, it can be considered that there is an 80% probability that the actual measured value of solar radiation is greater than 0.50 times the predicted value of solar radiation. Also, in the case of solar radiation data belonging to the numerical range F, it can be considered that there is an 80% probability that the actual measured value of solar radiation is greater than 0.31 times the predicted value of solar radiation.

[0075] In this way, the predicted power generation derivation device 2 can set the third ratio, which is the third ratio at which the cumulative value of the proportion of the solar radiation in each numerical range is a predetermined value (such as the value "20%" shown in FIG. 7 and described above) from the smallest cumulative value when the third ratios of the solar radiation data belonging to each numerical range are accumulated in ascending order, as the conversion ratio from the predicted value of the solar radiation corresponding to each numerical range. For example, when the predetermined value is set to 20%, "0.50" is set as the conversion ratio for numerical range G, and "0.31" is set as the conversion ratio for numerical range F. Here, the above-mentioned predetermined value can be freely set and stored in the storage device 3. Moreover, the above-mentioned predetermined value of 20% is given for illustrative purposes, and the numerical value can be appropriately set.

[0076] Then, when the predicted value of solar radiation and the predicted value of extra-atmospheric solar radiation at the location where the solar cell device 12 is installed are obtained, the predicted power generation derivation device 2 determines which of the multiple numerical ranges set for the first ratio the ratio of the predicted value of solar radiation to the predicted value of extra-atmospheric solar radiation belongs to (for example, whether it belongs to numerical range G or numerical range F, etc.), and derives the product of the predicted value of solar radiation and the conversion ratio set in the determined numerical range as an estimated value of solar radiation to be obtained at least at the location where the solar cell device 12 is installed.

[0077] The predicted power generation deriving device 2 can derive the trend of the estimated solar radiation by performing the above calculations using information on the trend of the predicted value of solar radiation and the trend of extraterrestrial solar radiation at the location where the solar cell device 12 is installed at the target date and time. Then, the predicted power generation deriving device 2 can derive the trend of the predicted lower limit power generation predicted for the power generation of the solar cell device 12 based on the trend of the estimated solar radiation.

[0078] As described above, even if a predicted value of the amount of solar radiation is obtained from the information providing server device 4 that performs a weather forecast service, the amount of solar radiation changes depending on the actual weather. However, by referring to the predicted value of the amount of solar radiation in the past and the actual measured value of the amount of solar radiation, it is possible to estimate at least how much solar radiation can be obtained with a certain degree of probability. For example, a predetermined conversion ratio can be derived, and the product of the predicted value of the amount of solar radiation and the conversion ratio can be derived as an estimated value of the amount of solar radiation that can be estimated to be obtained at least. Then, based on the estimated value of the amount of solar radiation, the above-mentioned predicted lower limit power generation can be derived. Therefore, in this embodiment, for each of a plurality of numerical ranges, the third ratio at which the cumulative value of the existence ratio when the third ratios of the solar radiation data belonging to each numerical range are accumulated in order from the smallest to the smallest is set as the conversion ratio from the predicted value of the amount of solar radiation corresponding to the numerical range. Here, the third ratio is the second ratio (the actual measured value of the amount of insolation to the amount of extraterrestrial insolation) to the first ratio (the predicted value of the amount of insolation to the amount of extraterrestrial insolation), and therefore corresponds to the ratio of the actual measured value of the amount of insolation to the predicted value of the amount of insolation. Therefore, when the predicted value of the amount of insolation is determined, it is expected that at least the amount of insolation (estimated value of insolation) that is the product of the predicted value of the amount of insolation and the above conversion ratio can be probabilistically obtained. Then, the trend of the predicted lower limit power generation power can be derived based on the trend of the estimated value of the amount of insolation.

[0079] <Fourth embodiment> In the fourth embodiment, a fuel cell device 13A(13) that has the functions of the power generation device 13 used in the above-mentioned power supply system and generates both heat and electricity will be described as an example of the power generation device 13. Descriptions of the same configuration as in the above-mentioned embodiments will be omitted.

[0080] FIG. 8 is a diagram showing the configuration of the power supply system. In this embodiment, the power generation device 13 is realized by a fuel cell device 13A that generates both heat and electricity. The fuel cell device 13A includes a fuel reforming section 16 that reforms a raw fuel such as city gas supplied to generate a fuel gas containing hydrogen, and a fuel cell section 17 that generates power using the fuel gas generated by the fuel reforming section 16 and oxygen. The generated power of the fuel cell section 17 is supplied to the power line 11. In addition, the heat generated by the fuel cell device 13A including the fuel cell section 17 is stored in a heat storage device using a heat medium. The heat medium supplied from the heat storage device is temperature-adjusted by a heat source device 21 that burns a raw fuel such as city gas to generate heat, and is then supplied to a heat load section 22.

[0081] For example, in the example shown in Fig. 8, the heat storage device is a hot water storage tank 18 that stores hot water as a heat medium. Relatively low-temperature hot water stored in the lower part of the hot water storage tank 18 is supplied to the fuel cell unit 17 through the outward path 19a of the hot water circulation path 19, and relatively high-temperature hot water after heat recovery in the fuel cell unit 17 flows into the upper part of the hot water storage tank 18 through the return path 19b of the hot water circulation path 19. When hot water is used in the heat load unit 22 and is supplied from the upper part of the hot water storage tank 18 to the heat source unit 21, clean water is supplied to the lower part of the hot water storage tank 18 from the water supply path. In this way, relatively high-temperature hot water exists in the upper part of the hot water storage tank 18, and relatively low-temperature hot water exists in the lower part of the hot water storage tank 18.

[0082] In such a power supply system, the hot water storage tank 18 recovers and stores the heat discharged from the fuel cell section 17, or in other words, the hot water storage tank 18 plays a role in cooling the fuel cell section 17. Therefore, when there is little or no heat utilization in the thermal load section 22, the hot water storage tank 18 only receives heat from the fuel cell section 17, and high-temperature hot water is also stored in the lower part of the hot water storage tank 18, and this high-temperature hot water must be used to cool the fuel cell section 17. Eventually, the hot water storage tank 18 will no longer be able to recover heat and cool the fuel cell section 17.

[0083] In the example shown in FIG. 8, a temperature sensor T1 is provided in the forward path 19a of the hot water circulation path 19. A radiator 20 capable of radiating heat from the hot water flowing through the hot water circulation path 19 is also provided. The temperature sensor T1 measures the temperature of the hot water flowing from the hot water storage tank 18 toward the radiator 20. When the temperature of the hot water measured by the temperature sensor T1 is equal to or higher than a predetermined temperature, the radiator 20 performs a heat radiation operation to lower the temperature of the hot water flowing through the forward path 19a of the hot water circulation path 19, and does not perform a heat radiation operation when the temperature of the hot water measured by the temperature sensor T1 is lower than the predetermined temperature. By performing such an operation by the radiator 20, the temperature of the hot water supplied to the fuel cell unit 17 is maintained low, and the fuel cell unit 17 is cooled well.

[0084] Considering that the cost of raw fuel is required to generate heat and electricity in the fuel cell device 13A having the fuel cell section 17 and the heat source unit 21, it can be said that the first cost per unit energy required to generate heat and electricity using the fuel cell device 13A when it is assumed that the generated heat is utilized is lower than the second cost per unit energy required to generate heat and electricity using the fuel cell device 13A when it is assumed that the generated heat is not utilized.

[0085] In this embodiment, the fuel cell device 13A can communicate information with the external server device 6 via the information communication line 5. The external server device 6 may be the same server device as the predicted power generation power deriving device 2, or may be a different server device. The fuel cell device 13A can receive a command from the external server device 6 to perform a power generation adjustment operation, that is, a command to perform a power generation adjustment operation to adjust the power generation power of the fuel cell device 13A so that the sum of the power generation power of the fuel cell device 13A and the predicted lower limit power generation power derived by the predicted power generation power deriving device 2 follows the load power of the power load device 14 connected to the power line 11. The fuel cell device 13A determines whether to perform a power generation adjustment operation, taking into consideration whether the situation is such that the heat generated by the fuel cell device 13A is utilized, as described below.

[0086] [Operation example 1] Specifically, when the fuel cell device 13A receives a command to perform power generation adjustment operation from the external server device 6, if a specified heat utilization condition indicating that the generated heat is in a situation where it can be utilized is satisfied, the fuel cell device 13A does not perform power generation adjustment operation, and if the heat utilization condition is not satisfied, the fuel cell device 13A performs power generation adjustment operation.

[0087] The heat utilization conditions are, for example, that the temperature of hot water measured by temperature sensor T1 is equal to or higher than a set temperature, that radiator 20 is in heat dissipation operation, etc. In other words, when hot water of a temperature equal to or higher than a set temperature is present at the bottom of hot water storage tank 18, and the temperature of hot water measured by temperature sensor T1 is equal to or higher than the set temperature, it means that hot water is not being discharged from hot water storage tank 18 to heat load section 22. Similarly, when radiator 20 is in heat dissipation operation, it means that the temperature of hot water measured by temperature sensor T1 is equal to or higher than a predetermined temperature, i.e., hot water is not being discharged from hot water storage tank 18 to heat load section 22.

[0088] Furthermore, when the power generation adjustment operation is performed, the power generated by the fuel cell device 13A becomes smaller than the load power of the power load device 14. In other words, when the power generation adjustment operation is performed, it means that the heat generated by the fuel cell device 13A decreases. Therefore, when the heat utilization condition is satisfied (i.e., when most of the generated heat is utilized), the amount of heat generated by the fuel cell device 13A decreases when the power generation adjustment operation is performed, and the operating cost (e.g., the cost of raw fuel) of the heat source device 21 for generating the reduced amount of heat increases. However, in this operation example 1, the fuel cell device 13A does not perform the power generation adjustment operation when the heat utilization condition is satisfied, so that the increase in the operating cost of the heat source device 21 as described above can be suppressed. On the other hand, when the heat utilization condition is not satisfied, the heat generated by the fuel cell device 13A is permitted to decrease, so the fuel cell device 13A performs the power generation adjustment operation.

[0089] [Operation example 2] When the fuel cell device 13A receives a command from the external server device 6 to perform power generation adjustment operation, if a specified heat utilization condition indicating that the generated heat is in a state where it can be utilized continues for a specified period of time or more, the fuel cell device 13A does not perform power generation adjustment operation, and if the heat utilization condition does not continue for a specified period of time or more, the fuel cell device 13A performs power generation adjustment operation.

[0090] Furthermore, when the power generation adjustment operation is performed, the power generated by the fuel cell device 13A becomes smaller than the load power of the power load device 14. In other words, the power generation adjustment operation means that the heat generated by the fuel cell device 13A decreases. Therefore, when the state in which the heat utilization condition is satisfied continues for a predetermined period or more (i.e., when the state in which most of the generated heat is utilized continues for a predetermined period or more), the power generation adjustment operation reduces the amount of heat generated by the fuel cell device 13A, and the operating cost (e.g., the cost of raw fuel) of the heat source device 21 for generating the reduced amount of heat increases. However, in this operation example 2, the fuel cell device 13A does not perform the power generation adjustment operation when the state in which the heat utilization condition is satisfied continues for a predetermined period or more, so that the increase in the operating cost of the heat source device 21 as described above can be suppressed. On the other hand, when the heat utilization condition is not satisfied for a predetermined period or more, the heat generated by the fuel cell device 13A is allowed to decrease, and the fuel cell device 13A performs the power generation adjustment operation.

[0091] [Operation example 3] The fuel cell device 13A, based on a comparison result between the power selling price per unit energy when the power generated by the solar cell device 12 is sold to the power grid 1, a first cost unit price per unit energy required to generate heat and electricity using the fuel cell device 13A on the assumption that the generated heat is utilized, and a second cost unit price per unit energy required to generate heat and electricity using the fuel cell device 13A on the assumption that the generated heat is not utilized, if the first cost unit price and the second cost unit price are greater than the power selling price, the external server device 6 When a command to perform power generation adjustment operation is received from the external server device 6, the power generation adjustment operation is performed, and when the first cost unit price is smaller than the power selling price and the second cost unit price is greater than the power selling price, when a command to perform power generation adjustment operation is received from the external server device 6, if a predetermined heat utilization condition indicating that the generated heat is in a situation where it can be utilized is not satisfied, the power generation adjustment operation is performed, and if the heat utilization condition is satisfied, the power generation adjustment operation is not performed, and when the first cost unit price and the second cost unit price are smaller than the power selling price, the power generation adjustment operation is not performed even if a command to perform power generation adjustment operation is received from the external server device 6.

[0092] Figures 9 to 11 are diagrams showing the results of a comparison between the electricity selling price Pa of the solar cell device 12, the first cost unit price (with heat utilization) Pb when it is assumed that the generated heat is utilized, and the second cost unit price (without heat utilization) Pc when it is assumed that the generated heat is not utilized.

[0093] When the power generation adjustment operation is performed, the power generated by the fuel cell device 13A becomes smaller than the load power of the power load device 14, so it is considered that the power (i.e., power to be sold) that is generated by the solar cell device 12 and flows back to the power grid 1 will decrease. Therefore, when the power generation adjustment operation is performed, the profit that can be calculated using the power selling price will decrease. In addition, when the power generation adjustment operation is performed, that is, the power generated by the fuel cell device 13A becomes smaller, it is considered that the cost that can be calculated using the first cost unit price per unit energy required to generate heat and electricity when the generated heat is utilized will decrease, and the cost that can be calculated using the second cost unit price per unit energy required to generate heat and electricity when the generated heat is not utilized will decrease.

[0094] 9, when the first cost unit price Pb and the second cost unit price Pc are greater than the power selling price Pa, the power generation adjustment operation is performed upon receiving a command to perform the power generation adjustment operation from the external server device 6. As a result, when the power generation adjustment operation is performed, the reduction in costs due to the reduction in the power generation of the fuel cell device 13A can be made to exceed the reduction in profits due to the reduction in the power sold of the power generated by the solar cell device 12.

[0095] 10, when the first cost unit price Pb is smaller than the power selling price Pa and the second cost unit price Pc is larger than the power selling price Pa, if a command to perform power generation adjustment operation is received from the external server device 6, the power generation adjustment operation is performed if a predetermined heat utilization condition indicating that the generated heat is utilized is not satisfied, and the power generation adjustment operation is not performed if the heat utilization condition is satisfied. This makes it possible to ensure that the reduction in costs due to the reduction in the power generated by the fuel cell device 13A exceeds the reduction in profits due to the reduction in the power sold by the solar cell device 12 when the power generation adjustment operation is performed. Furthermore, it is possible to ensure that the reduction in profits due to the reduction in the power sold by the solar cell device 12 does not exceed the reduction in costs due to the reduction in the power generated by the fuel cell device 13A when the power generation adjustment operation is performed.

[0096] 11, when the first cost unit price Pb and the second cost unit price Pc are smaller than the power selling price Pa, the power generation adjustment operation is not performed even if a command to perform the power generation adjustment operation is received from the external server device 6. This makes it possible to ensure that when the power generation adjustment operation is performed, the reduction in profits caused by the reduction in the power sold of the power generated by the solar cell device 12 does not exceed the reduction in costs caused by reducing the power generated by the fuel cell device 13A.

[0097] <Another embodiment> <1> In the above embodiment, the configuration of the power supply system has been specifically described, but the configuration can be appropriately changed. For example, the predicted generated power deriving device 2 and the storage device 3 may be installed inside the facility 10. Alternatively, the predicted generated power deriving device 2 may be realized using a control unit (not shown) of the power generation device 13.

[0098] <2> In the above embodiment, a day is divided into 30-minute intervals, and the first output coefficient and the like are handled as values ​​for each 30-minute interval. However, the time intervals to be used can be changed as appropriate. For example, a day may be divided into hourly intervals, and the first output coefficient and the like may be handled as values ​​for each hour.

[0099] <3> 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, provided that no contradiction arises. Furthermore, the embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0100] INDUSTRIAL APPLICABILITY The present invention can be applied to a power supply system and a fuel cell device that can self-consume as much generated power as possible and minimize the need to purchase electricity. [Explanation of symbols]

[0101] 1: Power system 2: Predicted power generation calculation device 6: External server device 11: Power lines 12: Solar cell device 13: Power generation equipment 13A:Fuel cell device 14:Power load device Pa: Electricity selling price Pb: First cost unit price Pc: Secondary cost unit price

Claims

1. A power supply system including a solar cell device and a power generation device connected to a power line that is connected to a power grid, a predicted power generation deriving device that derives a transition of a predicted lower limit power generation power predicted for the power generation power of the solar cell device, The power generation device performs a power generation adjustment operation to adjust the power generation power of the power generation device so that the sum of the power generation power of the power generation device and the predicted lower limit power generation power derived by the predicted power generation derivation device tracks the load power of a power load device connected to the power line.

2. The power supply system of claim 1, wherein the predicted power generation derivation device derives the trend of the predicted lower limit power generation by referring to the trend of the lower limit solar radiation, which is the lower limit of a confidence interval set for the predicted value of solar radiation at the location where the solar cell device is installed.

3. The predicted power generation derivation device includes: a first output coefficient that can be used to derive a predicted maximum power generation power that is predicted to be generated by the solar cell device at a target date and time by multiplying the first output coefficient by a rated power generation power of the solar cell device; a second output coefficient that is expressed as a function of the lower limit solar radiation and that can be used to derive the predicted lower limit power generation power that is predicted to be generated by the solar cell device at a target date and time by multiplying the predicted maximum power generation power by the second output coefficient; The power supply system according to claim 2 , wherein the predicted lower limit generated power is derived by multiplying the rated generated power by the first output coefficient and the second output coefficient.

4. The predicted power generation derivation device includes: a first output coefficient that can be used to derive a predicted maximum power generation power that is predicted to be generated by the solar cell device at a target date and time by multiplying the first output coefficient by a rated power generation power of the solar cell device; and a third output coefficient that is a ratio of a first predicted amount of solar radiation, which is a predicted value of solar radiation on a clear day at a location where the solar cell device is installed, to a second predicted amount of solar radiation, which is an amount of solar radiation predicted based on image information that can estimate the amount of clouds at a location where the solar cell device is installed. The power supply system according to claim 1 , wherein the predicted lower limit generated power is derived by multiplying the rated generated power by the first output coefficient and the third output coefficient.

5. The predicted power generation derivation device includes: Collecting solar radiation data consisting of extraterrestrial solar radiation, predicted values ​​of solar radiation, and actual measured values ​​of solar radiation at each of a plurality of past times; Deriving, for each time of the solar radiation data, a first ratio which is a ratio of a predicted value of the solar radiation to the extraterrestrial solar radiation, and a second ratio which is a ratio of an actual value of the solar radiation to the extraterrestrial solar radiation; The solar radiation data is classified into one of a plurality of numerical ranges set for the first ratio; deriving a third ratio, which is a ratio of the second ratio to the first ratio for each of the solar radiation amount data belonging to each of the plurality of numerical ranges; The third ratio, in which the cumulative value of the existence ratio when the third ratios of each of the solar radiation amount data belonging to the numerical range are accumulated in ascending order from the smallest, is set to a predetermined value from the smallest as a conversion ratio from the predicted value of the solar radiation amount corresponding to the numerical range; when the predicted value of the amount of solar radiation and the predicted value of extra-atmospheric solar radiation at a location where the solar cell device is installed at a target date and time are obtained, a ratio of the predicted value of the amount of solar radiation to the predicted value of the extra-atmospheric solar radiation is determined to which of the plurality of numerical ranges set for the first ratio belongs, and a product of the predicted value of the amount of solar radiation and the conversion ratio set to the determined numerical range is derived as an estimated value of solar radiation obtained at least at the location where the solar cell device is installed; The power supply system according to claim 1 , wherein the transition of the predicted lower limit generated power is derived based on the transition of the estimated value of the amount of solar radiation.

6. 6. A fuel cell device that has the function of the power generation device used in the power supply system according to claim 1 and generates both heat and electricity.

7. A fuel cell device as described in claim 6, wherein when a command to perform the power generation adjustment operation is received from an external server device, if a predetermined heat utilization condition indicating that the generated heat is in a situation in which it can be utilized is satisfied, the power generation adjustment operation is not performed, and if the heat utilization condition is not satisfied, the power generation adjustment operation is performed.

8. A fuel cell device as described in claim 6, wherein, when a command to perform the power generation adjustment operation is received from an external server device, if a specified heat utilization condition indicating that the generated heat is in a situation where it can be utilized continues for a specified period of time or more, the power generation adjustment operation is not performed, and if the heat utilization condition does not continue for the specified period of time or more, the power generation adjustment operation is performed.

9. based on a comparison result between a selling price per unit energy when the power generated by the solar cell device is sold to the power grid, a first cost per unit energy required to generate heat and electricity when it is assumed that the generated heat is utilized, and a second cost per unit energy required to generate heat and electricity when it is assumed that the generated heat is not utilized, When the first cost unit price and the second cost unit price are greater than the power selling price, the power generation adjustment operation is performed upon receiving a command to perform the power generation adjustment operation from an external server device; When the first cost unit price is smaller than the power selling price and the second cost unit price is larger than the power selling price, when a command to perform the power generation adjustment operation is received from an external server device, if a predetermined heat utilization condition indicating that the generated heat is in a state where it can be utilized is not satisfied, the power generation adjustment operation is performed, and if the heat utilization condition is satisfied, the power generation adjustment operation is not performed; 7. The fuel cell device according to claim 6, wherein when the first cost unit price and the second cost unit price are smaller than the power selling price, the power generation adjustment operation is not performed even if a command to perform the power generation adjustment operation is received from an external server device.

Images