Power generation equipment and fuel cell equipment

Abstract

To provide a power generation device that can consume as much of the generated electricity as possible within the country and minimize the amount of electricity purchased from the grid. [Solution] The power generation device 23 is connected to a power line 11, a solar cell device 12 and a power load 14 are connected to it, and an input receiving unit 26 is provided to receive information from a user. The operation control unit 24 is configured to derive a predicted lower limit of power generation for the solar cell device 12 based on the predicted minimum power generation of the solar cell device 12 received by the input receiving unit 26, or a predicted minimum value derived by multiplying the predicted maximum power generation of the solar cell device 12 received by the input receiving unit 26 by a predetermined coefficient, and to perform a power generation adjustment operation that adjusts the power generation of the power generation unit 17 so that the sum of the power generation of the power generation unit 17 and the predicted lower limit of power generation follows the load power of the power load 14.

Description

Technical Field

[0001] The present invention relates to a power generation device and a fuel cell device including a power generation unit connected to a power line connected to a power system and an operation control unit that controls the operation of the power generation unit.

Background Art

[0002] There is a power supply system in which a power generation device such as a solar cell device and a fuel cell are installed side by side in facilities such as residential houses and business offices. In such a power supply system, when power generation by the solar cell device and power generation by the power generation device are performed simultaneously, the sum of their generated powers may be greater than the load power of the power load provided in the facility. That is, a part of the generated power is not used in the facility and flows backward to the power system outside the facility. Still, even in such a case, if power generation control is performed to keep the generated power of the power generation device such as a fuel cell low, the sum of the generated powers of the solar cell device and the power generation device will not flow backward to the power system, or the power flowing backward can be reduced.

[0003] Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2021-158809) describes a power supply system aimed at improving the self-consumption of power generated by a solar cell device. Specifically, in the invention described in Patent Document 1, at the previous day stage, the load power and the generated power of the solar cell device for the next day are predicted, and the surplus power for the next day (= generated power of the solar cell device - load power) is predicted, and it is determined whether there is a time period when the surplus power > β. And when there is a time period when the surplus power > β, a power generation request instruction to the fuel cell is given in a time period when it is predicted that no surplus power will be generated and a large amount of purchased power will be required. As a result, the fuel cell generates power in the time period when it receives the power generation request instruction for the next day and stops generating power in the time period when it does not receive the power generation request instruction. For example, in "around 8 to 18 o'clock on the second day" shown in FIG. 5 described in Patent Document 1, the fuel cell has stopped generating power, and the power demand is covered by the generated power of the solar cell device. Still, when the fuel cell generates power, as shown in FIG. 5 of Patent Document 1, load-following operation is performed so that the generated power of the fuel cell becomes equal to the power demand. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-158809 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the power supply system described in Patent Document 1, the time period when the solar cell is expected to generate a large amount of power is predetermined in the forecast stage the day before, and this time period is set as the time period when the fuel cell stops generating power. In other words, in the power supply system described in Patent Document 1, there is a problem that the fuel cell is not fully utilized during the time when the solar cell is generating power during the day.

[0006] Furthermore, even if it is predicted that the solar panel will generate a large amount of power, if the sun is obscured by clouds on the day of use, the actual power generated by the solar panel will decrease significantly. Therefore, as described in Patent Document 1, if the fuel cell stops generating power, the power generated inside the facility cannot meet the load power needs, resulting in a problem where a very large amount of power must be purchased from the power grid.

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

[0008] Furthermore, in order to reduce reverse power flow to the power grid and the amount of power purchased from the power grid, it is possible to control power generation by measuring the power generated by the solar panels or the power at the facility's power receiving point and increasing or decreasing the power generated by the fuel cell according to the measurement results. However, there is a problem in that the cost of installing equipment to measure the power generated by the solar panels or the power at the facility's power receiving point is high.

[0009] The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a power generation device and a fuel cell device that can consume as much of the generated electricity as possible in-house and suppress the generation of electricity purchased from the power grid as much as possible. [Means for solving the problem]

[0010] A characteristic configuration of the power generation device according to the present invention for achieving the above objective is a power generation device comprising a power generation unit connected to a power line connected to a power grid and an operation control unit that controls the operation of the power generation unit, The aforementioned power line is connected to a solar cell device and a power load. It is equipped with an input reception unit that receives information input from users, The operation control unit is configured to derive a predicted lower limit of power generation for the solar cell system based on the predicted minimum power generation of the solar cell system received by the input receiving unit, or the predicted minimum power generation obtained by multiplying the predicted maximum power generation of the solar cell system received by the input receiving unit by a predetermined coefficient, and to perform a power generation adjustment operation that adjusts the power generation of the power generation unit so that the sum of the power generation of the power generation unit and the predicted lower limit of power generation follows the load power of the power load. Here, the operation control unit may derive the predicted minimum value as the predicted lower limit of power generation during the time period in which the power generation adjustment operation is performed. Furthermore, the operation control unit may derive the trend of the predicted lower limit of power generation based on a reference increase / decrease curve representing the increase / decrease in power generation when the power generation of the solar cell device increases and decreases between sunrise and sunset, and the predicted minimum value.

[0011] With the above-described configuration, if the user knows the past power generation values ​​of the solar cell system, the user can easily deduce the future predicted minimum or maximum power generation values ​​of the solar cell system. The operation control unit then derives a predicted lower limit power generation value for the solar cell system based on the predicted minimum power generation value of the solar cell system received by the input reception unit, or the predicted minimum value derived by multiplying the predicted maximum power generation value of the solar cell system received by the input reception unit by a predetermined coefficient. Based on this, it can perform power generation adjustment operation, adjusting the power generation of the power generation unit so that the sum of the power generation of the power generation unit and the predicted lower limit power generation value follows the load power of the power load. As a result, even if the power generation of the solar cell system drops to the predicted lower limit power generation value due to cloud cover, the load power of the power load is expected to be covered by the power generation of the power generation unit and the power generation of the solar cell system. In other words, even if the power generation of the solar cell system decreases due to cloud cover, the generation of electricity purchased from the power grid is suppressed. Furthermore, if the sun is not obscured and the power generated by the solar panels is sufficiently large, the sum of the power generated by the generator and the solar panels may exceed the load power of the power load, potentially causing the surplus power to flow back into the power grid. However, in this configuration, the power generated by the generator is adjusted to be less than the load power of the power load, so even if such surplus power occurs, its magnitude will be kept small. In other words, the power generated by the generator and the solar panels will be consumed as much as possible within the grid. Therefore, it is possible to provide a power generation device that consumes as much of the generated electricity as possible in-house and minimizes the amount of electricity purchased from the power grid.

[0012] Another characteristic configuration of the power generation apparatus according to the present invention is that the operation control unit performs the power generation adjustment operation during the adjustment target time period received by the input reception unit from the user.

[0013] According to the above feature configuration, power generation adjustment operation can be performed during the power generation adjustment time period entered by the user.

[0014] Another characteristic configuration of the power generation apparatus according to the present invention is that the operation control unit stops the ongoing power generation adjustment operation in response to a termination instruction received by the input reception unit from the user.

[0015] According to the above configuration, the user can, at their discretion, stop the ongoing power generation adjustment operation.

[0016] The characteristic configuration of the fuel cell device according to the present invention for achieving the above objective is that it has the functions of the above-mentioned power generation device and generates both heat and electricity.

[0017] According to the above-described configuration, it is possible to provide a fuel cell device that has the function of a power generation device that consumes as much of the generated electricity as possible in-house and suppresses the generation of electricity purchased from the power grid as much as possible.

[0018] Another characteristic configuration of the fuel cell device according to the present invention is that the operation control unit does not perform the power generation adjustment operation if predetermined heat utilization conditions indicating that the generated heat is in a state where it can be utilized are met, and performs the power generation adjustment operation if the heat utilization conditions are not met.

[0019] When power generation adjustment operation is performed, the power generated by the fuel cell system becomes less than the load power of the power load. In other words, power generation adjustment operation means that less heat is generated by the fuel cell system. Therefore, when the heat utilization conditions are met (i.e., when most of the generated heat is utilized), power generation adjustment operation reduces the amount of heat generated by the fuel cell system, which increases the operating cost of, for example, the heat source equipment needed to generate the lost heat. However, with this feature configuration, the fuel cell system does not perform power generation adjustment operation when the heat utilization conditions are met, thus suppressing the increase in operating costs of the heat source unit as described above.

[0020] Another characteristic configuration of the fuel cell device according to the present invention is that if a predetermined heat utilization condition indicating that the generated heat is in a situation where it is utilized is satisfied continuously for a predetermined period or more, the power generation adjustment operation is not performed, and if the state where the heat utilization condition is satisfied does not continue for the predetermined period or more, the power generation adjustment operation is performed.

[0021] When the power generation adjustment operation is performed, the generated power of the fuel cell device becomes smaller than the load power of the power load. That is, performing the power generation adjustment operation means that the heat generated by the fuel cell device decreases. Therefore, when the state where the heat utilization condition is satisfied continues for a predetermined period or more (that is, when the situation where most of the generated heat is utilized continues for a predetermined period or more), when the power generation adjustment operation is performed, the heat generation amount of the fuel cell device decreases, so for example, the operation cost of a heat source machine for generating the reduced amount of heat increases. However, in this characteristic configuration, since the fuel cell device does not perform the power generation adjustment operation when the state where the heat utilization condition is satisfied continues for a predetermined period or more, it is possible to suppress an increase in the operation cost of the heat source machine as described above.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram showing the configuration of a power supply system including a fuel cell device. [Figure 2] It is a diagram for explaining an example of a method for deriving the predicted lower limit power generation power. [Figure 3] It is a diagram for explaining an example of a method for deriving the predicted lower limit power generation power. [Figure 4] It is a diagram for explaining an example of a method for deriving the predicted lower limit power generation power. [Figure 5] It is a diagram for explaining an example of a method for deriving the predicted lower limit power generation power. [Figure 6] It is a flowchart for explaining the power generation control of the fuel cell device.

Embodiments for Carrying Out the Invention

[0023] A power supply system according to an embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows the configuration of a power supply system equipped with a fuel cell device 23 as a power generation device. As shown in the figure, the power supply system includes a solar cell device 12 and a fuel cell device 23 connected to a power line 11 that is connected to a power grid 1. In the example shown in Figure 1, the solar cell device 12 and the fuel cell device 23 are installed in a facility 10 such as a dwelling or office. A power load 14 is also connected to the power line 11 of the facility 10. As a result, the power load 14 can receive power from at least one of the solar cell device 12, the fuel cell device 23, and the power grid 1.

[0024] A solar power display unit 13 is connected to the solar cell device 12, which displays information about the power generated by the solar cell device 12. For example, the solar power display unit 13 can display the current power generated by the solar cell device 12, as well as the power generated by the solar cell device 12 in the past. As a result, users of the facility 10 can find out the power generated when the weather is sunny, when the weather is cloudy, etc., by looking at the display on the solar power display unit 13.

[0025] The fuel cell device 23 comprises a fuel cell unit 17 as a power generation unit connected to a power line 11 connected to the power grid 1, and an operation control unit 24 that controls the operation of the fuel cell unit 17. In addition, the fuel cell device 23 includes a fuel reforming unit 16 that reforms a supplied raw fuel such as city gas to produce a fuel gas containing hydrogen, and the fuel cell unit 17 generates electricity using the fuel gas and oxygen produced in the fuel reforming unit 16. The operation control unit 24 can adjust the power generated by the fuel cell unit 17 to a power between a predetermined minimum power generation power and a maximum power generation power (e.g., rated power generation power), and the power generated by the fuel cell unit 17 is supplied to the power line 11.

[0026] In addition, the fuel cell device 23 includes an information storage unit 25, an input receiving unit 26, and an information output unit 27.

[0027] The input receiving unit 26 receives information input from the user. The information output unit 27 can output information to the user by outputting text, images, sound, light, etc. These input receiving unit 26 and information output unit 27 can be implemented using a remote control or the like installed in the facility 10.

[0028] The operation control unit 24 can recognize the load power value of the power load 14. For example, a power measurement unit 15 is provided on the power line 11, and the measurement result is transmitted to the fuel cell device 23. The power measured by the power measurement unit 15 is the power supplied to the power load 14 from at least one of the power system 1 and the solar cell device 12. The operation control unit 24 can also recognize the power supplied by the fuel cell unit 17 to the power line 11 (i.e., generated power). As a result, the operation control unit 24 can recognize the sum of the power measured by the power measurement unit 15 and the generated power of the fuel cell unit 17 as the load power of the power load 14.

[0029] The fuel cell device 23 functions as a combined heat and power (CHP) device that generates both heat and electricity. In other words, the fuel cell device 23 is a device that has the functions of the power generation device of this embodiment and generates both heat and electricity. In this embodiment, the heat generated by the fuel cell device 23, including the fuel cell section 17, is stored in a heat storage device using a heat transfer medium. For example, the heat storage device can be realized using a hot water storage tank 18 that stores hot water as a heat transfer medium, as will be described later. The heat transfer medium supplied from the heat storage device is then temperature-controlled by a heat source unit 21 that generates heat by burning a raw fuel such as city gas, and then supplied to the heat load section 22.

[0030] In the example shown in Figure 1, the heat storage device is a hot water storage tank 18 that stores hot water as a heat transfer 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 forward path 19a of the hot water circulation path 19, and the relatively high-temperature hot water, after heat has been recovered 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. Also, when hot water is used in the heat load unit 22 and hot water is discharged from the upper part of the hot water storage tank 18 to the heat source unit 21, tap water is supplied to the lower part of the hot water storage tank 18 from the water supply path. Thus, 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.

[0031] In such a power supply system, the hot water storage tank 18 recovers and stores the heat discharged from the fuel cell unit 17. In other words, the hot water storage tank 18 also plays a role in cooling the fuel cell unit 17. Therefore, if there is little or no heat utilization in the heat load unit 22, the hot water storage tank 18 will only receive heat from the fuel cell unit 17, and high-temperature hot water will accumulate in the lower part of the hot water storage tank 18. This high-temperature hot water must then be used to cool the fuel cell unit 17. Ultimately, the heat recovery from the hot water stored in the hot water storage tank 18 will no longer be sufficient to cool the fuel cell unit 17.

[0032] In the example shown in Figure 1, a temperature sensor T1 is installed in the forward path 19a of the hot water circulation path 19. A heat radiator 20 is also provided that can dissipate heat from the hot water flowing through the hot water circulation path 19. The temperature sensor T1 measures the temperature of the hot water flowing from the hot water storage tank 18 to the heat radiator 20. The operation control unit 24 then operates the heat radiator 20 to dissipate heat to lower the temperature of the hot water flowing in the forward path 19a of the hot water circulation path 19 if the temperature of the hot water measured by the temperature sensor T1 is above a predetermined temperature, and does not operate the heat radiator 20 if the temperature of the hot water measured by the temperature sensor T1 is below the predetermined temperature. By operating the heat radiator 20 in this way, the temperature of the hot water supplied to the fuel cell unit 17 is kept low, and the cooling of the fuel cell unit 17 is performed effectively.

[0033] The power generated by the solar cell system 12 varies depending on the amount of solar radiation. For example, if the weather during the day is continuously rainy or cloudy, the amount of solar radiation remains low and does not fluctuate significantly throughout the day. On the other hand, if the weather during the day is sunny, the amount of solar radiation can fluctuate significantly throughout the day depending on whether or not the sun is obscured by clouds. In other words, if the weather during the day is sunny and the sun is obscured by clouds, the power generated by the solar cell system 12 may suddenly decrease.

[0034] The solid line in Figure 2 shows the actual power generation of the solar cell system 12. As shown in the figure, the solar cell system 12 generates power from around 7:00 AM to around 4:30 PM during the daytime. During this period, there is a time when the power generation of the solar cell system 12 drops sharply, which is due to a temporary decrease in solar radiation caused by cloud cover.

[0035] From the perspective of effectively utilizing the power generated by the solar cell system 12 at the facility 10, it is preferable that all of the power generated by the solar cell system 12 be consumed by the power load 14 at the facility 10. For example, if power generation control (for example, power generation adjustment operation described later) is performed in advance to keep the power generated by the fuel cell system 23 low, the power generated by the solar cell system 12 can be consumed by the facility 10 in both cases: when the amount of solar radiation is not reduced by clouds, and when the amount of solar radiation is reduced by clouds.

[0036] In the fuel cell system 23 of this embodiment, the operation control unit 24 derives a predicted lower limit of power generation for the solar cell system 12 based on the predicted minimum power generation of the solar cell system 12 received by the input receiving unit 26, or the predicted minimum power generation obtained by multiplying the predicted maximum power generation of the solar cell system 12 received by the input receiving unit 26 by a predetermined coefficient, and is configured to perform a power generation adjustment operation that adjusts the power generation of the fuel cell unit 17 so that the sum of the power generation of the fuel cell unit 17 and the predicted lower limit of power generation follows the load power of the power load 14.

[0037] Here, the operation of the fuel cell device 23 in a state in which the sum of the power generated by the fuel cell device 23 and the predicted lower limit power generated follows the load power of the power load 14 means, for example, operation in which the sum of the power generated by the fuel cell device 23 and the predicted lower limit power generated is equal to the load power of the power load 14, or operation in which the sum of the power generated by the fuel cell device 23 and the predicted lower limit power generated is greater than or less than the load power of the power load 14 by a predetermined amount.

[0038] Furthermore, if power generation adjustment operation is not performed, the operation control unit 24 may perform operations such as maintaining the power generated by the fuel cell device 23 at a constant value, or load-following operation, which adjusts the power generated by the fuel cell unit 17 so that the power generated by the fuel cell unit 17 follows the load power of the power load 14. This load-following operation may include, for example, operations that maintain the power generated by the fuel cell device 23 to be equal to the load power of the power load 14, or operations that maintain the power generated by the fuel cell device 23 to be a predetermined amount greater than or less than the load power of the power load 14.

[0039] The operation control unit 24 can derive the predicted lower limit of power generation for the solar cell device 12 in the following manner.

[0040] [Derivation Example 1] Figure 2 illustrates an example of deriving the trend of the predicted lower limit of generated power. Users can find out the generated power of the solar cell 12 by checking the display contents of the solar cell power display unit 13 connected to the solar cell 12. For example, users can find out information such as the current generated power of the solar cell 12 and the generated power of the solar cell 12 in the past. Therefore, users know the minimum value of the solar cell 12's daytime generated power in the past (i.e., the generated power when the weather is cloudy). Such a minimum value of the solar cell 12's generated power can also be considered as the predicted minimum value of the solar cell 12's generated power in the future. As a result, users can input, for example, the minimum value of the solar cell 12's generated power in the past that they have stored in their memory to the input receiving unit 26 as the predicted minimum value of the solar cell 12's generated power.

[0041] Furthermore, users can input the time period to be adjusted for power generation adjustment operation to the input reception unit 26. When the input reception unit 26 receives input from the user regarding the time period to be adjusted for power generation adjustment operation, the operation control unit 24 can perform power generation adjustment operation during that time period.

[0042] Alternatively, the operation control unit 24 can automatically determine the time period to be adjusted. For example, if the information storage unit 25 has information indicating the time period to be adjusted each day stored in advance, the operation control unit 24 can determine the time period to be adjusted when performing power generation adjustment operation on that day, based on the date and time information for the day and the time period for performing power generation adjustment operation each day that is stored in advance in the information storage unit 25.

[0043] In the example shown in Figure 2, the input receiving unit 26 receives input from the user for the predicted minimum power generation value of 1 kW for the solar cell device 12. Therefore, the operation control unit 24 derives the predicted minimum value as the predicted lower limit power generation value during the adjustment period in which power generation adjustment operation is performed, as shown by the dashed line in Figure 2. In other words, during the adjustment period, the predicted lower limit power generation value remains constant at the predicted minimum value.

[0044] [Derivation Example 2] Figure 3 illustrates an example 2 of the derivation of the trend of the predicted lower limit of generated power. As described above, the user can find out the generated power of the solar cell 12 by checking the display contents of the solar cell power display unit 13 connected to the solar cell 12. Therefore, the user knows the maximum value of the solar cell 12's daytime generated power in the past (i.e., the generated power when the weather is sunny). And such a maximum value of the solar cell 12's generated power can also be considered as the predicted maximum value of the solar cell 12's generated power in the future. As a result, the user can input, for example, the maximum value of the solar cell 12's generated power in the past that they have stored in their memory to the input receiving unit 26 as the predicted maximum value of the solar cell 12's generated power.

[0045] In the example shown in Figure 3, the input receiving unit 26 receives input from the user for the predicted maximum power output of the solar cell system 12, which is 5kW. Therefore, the operation control unit 24 derives a predicted minimum value, obtained by multiplying the predicted maximum power output of the solar cell system 12 received by the input receiving unit 26 by a predetermined coefficient, as the predicted lower limit power output during the adjustment period in which power generation adjustment operation is performed. For example, the coefficient is a value such as 0.2 and is stored in advance in the information storage unit 25. Then, the operation control unit 24 derives the predicted minimum value (1kW), obtained by multiplying the predicted maximum value (5kW) by the coefficient (0.2), as the predicted lower limit power output during the adjustment period in which power generation adjustment operation is performed.

[0046] [Derivation Example 3] Figure 4 illustrates the third example of derivation of the predicted lower limit of power generation. Similar to the first example described above, the user can find out the power generation of the solar cell 12 by checking the display on the solar cell power display unit 13 connected to the solar cell 12. As a result, the user can input, for example, the minimum value of past power generation of the solar cell 12 that they have stored in their memory to the input receiving unit 26 as the predicted minimum value of power generation of the solar cell 12.

[0047] Furthermore, the information storage unit 25 stores a reference increase / decrease curve, as shown by the dashed line in Figure 4, which represents the temporal increase and decrease in the power generated by the solar cell device 12 when the power generated increases and decreases between sunrise and sunset. Specifically, the reference increase / decrease curve is a curve connecting the reference power generated at each time point. The operation control unit 24 then derives the trend of the predicted lower limit power generated based on this reference increase / decrease curve and the predicted minimum value received from the user by the input reception unit 26.

[0048] For example, when the operation control unit 24 receives input for the predicted minimum power generation value of the solar cell device 12, it considers that predicted minimum value as the reference power generation value at a reference time (e.g., 12:00). The operation control unit 24 then adjusts the shape of the entire reference increase / decrease curve so that the reference power generation value at 12:00 on the reference increase / decrease curve becomes the predicted minimum value. For example, the operation control unit 24 derives the ratio between the received predicted minimum value and the reference power generation value at a reference time on the reference increase / decrease curve, and applies this ratio to the reference power generation value at all times on the reference increase / decrease curve to adjust the shape of the entire reference increase / decrease curve. The curve obtained by adjusting the shape is then determined as the curve showing the change in the predicted lower limit power generation value, which is shown by the dashed line in Figure 4.

[0049] Furthermore, the information storage unit 25 may store multiple reference increase / decrease curves determined according to the sunrise and sunset times that change daily. The operation control unit 24 may then select a reference increase / decrease curve suitable for the day to derive the predicted lower limit of power generation as described above.

[0050] Furthermore, the time set for the above reference time can be changed as needed.

[0051] Alternatively, the user may input the predicted minimum value of the power generated by the solar cell device 12, along with the time, to the input receiving unit 26. In this case, the operation control unit 24 considers the received predicted minimum value as the reference power generated at the time the input was received (input time). The operation control unit 24 then adjusts the shape of the entire reference increase / decrease curve so that the reference power generated at the input receiving time of the reference increase / decrease curve becomes the predicted minimum value, thereby determining a curve that shows the trend of the predicted lower limit power generated.

[0052] [Derivation Example 4] Figure 5 illustrates the derivation example 4 of the trend of the predicted lower limit of generated power. Similar to the derivation example 2 described above, the user can find out the generated power of the solar cell device 12 by checking the display contents of the solar cell power display unit 13 connected to the solar cell device 12. As a result, the user can input, for example, the maximum value of the solar cell device 12's generated power in the past that they have stored in their memory to the input receiving unit 26 as the predicted maximum value of the generated power of the solar cell device 12.

[0053] In the example shown in Figure 5, the input receiving unit 26 receives input from the user for the predicted maximum power output of the solar cell device 12, which is 5kW. The operation control unit 24 then determines the predicted minimum power output by multiplying the predicted maximum power output of the solar cell device 12 received by the input receiving unit 26 by a predetermined coefficient. For example, the coefficient is a value such as 0.2 and is stored in advance in the information storage unit 25. In the example shown in Figure 5, the operation control unit 24 determines the predicted minimum power output (1kW) which is derived by multiplying the predicted maximum power output (5kW) by the coefficient (0.2).

[0054] Furthermore, the information storage unit 25 stores a reference increase / decrease curve, as shown by the dashed line in Figure 5, which represents the increase and decrease in the power generated by the solar cell device 12 when the power generated increases and decreases between sunrise and sunset. Specifically, the reference increase / decrease curve is a curve connecting the reference power generated at each time point. The operation control unit 24 then derives the trend of the predicted lower limit power generated based on this reference increase / decrease curve and the predicted minimum value.

[0055] For example, the operation control unit 24 considers the predicted minimum value determined as described above as the reference power generation power at a reference time (e.g., 12:00). The operation control unit 24 then adjusts the overall shape of the reference increase / decrease curve so that the reference power generation power at 12:00 on the reference increase / decrease curve becomes the predicted minimum value, thereby determining the curve showing the trend of the predicted lower limit power generation power, as shown by the dashed line in Figure 5.

[0056] Figure 6 is a flowchart illustrating the power generation control of the fuel cell device 23. In step #20, the operation control unit 24 sets a target power generation power such that "Target power generation power = Load power of power load 14 - Predicted lower limit power generation power". In other words, it attempts to operate the fuel cell device 23 so that the sum of the power generated by the fuel cell device 23 (target power generation power) and the predicted lower limit power generation power follows the load power of power load 14 (i.e., maintains a state where the sum of the power generated by the fuel cell device 23 and the predicted lower limit power generation power is equal to the load power of power load 14). Here, the operation control unit 24 recognizes the sum of the power measured by the power measurement unit 15 at that time and its own power generation power at that time as the load power of power load 14 at that time. Then, the operation control unit 24 refers to the sum of the load power at that time and the predicted lower limit power generation power at that time to determine the target power generation power at that time.

[0057] Furthermore, the fuel cell device 23 cannot accommodate any target power generation value, and can only adjust the power generation to a range between a predetermined minimum power generation and a maximum power generation (e.g., rated power generation). Therefore, in steps #21 and #22, the operation control unit 24 determines whether the target power generation derived in step #20 is greater than or equal to the minimum power generation and less than or equal to the maximum power generation. If the target power generation derived in step #20 is greater than or equal to the minimum power generation and less than or equal to the maximum power generation (i.e., if the answer is "Yes" in both step #21 and step #22), the operation control unit 24 proceeds to step #23 and adjusts the power generation to the target power generation derived in step #20.

[0058] In response, if the target power generation derived in step #20 is less than the minimum power generation (i.e., if the answer in step #21 is "No"), the operation control unit 24 proceeds to step #24 and adjusts the power generation to the minimum power generation.

[0059] Furthermore, if the target power generation power derived in step #20 is greater than the maximum power generation power (i.e., if the answer is "Yes" in step #21 and "No" in step #22), the operation control unit 24 proceeds to step #25 and adjusts the power generation power to the maximum power generation power.

[0060] Then, in process #26, the operation control unit 24 adjusts the generated power to the value determined in process #23, process #24, or process #25 and generates power for a certain period of time. Furthermore, after a certain period of time has elapsed, the operation control unit 24 moves to process #20 and determines the target generated power again as described above. Since a certain period of time has elapsed, it is assumed that the predicted lower limit of generated power and the load power are different from the time when the generated power was previously determined. Therefore, it is assumed that the target generated power derived in process #20 will also be different from the value derived previously.

[0061] As described above, if the user knows what the past power generation values ​​of the solar cell system 12 have been, the user can easily come up with the predicted minimum or maximum future power generation values ​​of the solar cell system 12. The operation control unit 24 then derives the predicted transition of the predicted lower limit power generation value for the solar cell system 12 based on the predicted minimum power generation value of the solar cell system 12 received by the input reception unit 26, or the predicted minimum value derived by multiplying the predicted maximum power generation value of the solar cell system 12 received by the input reception unit 26 by a predetermined coefficient, and performs power generation adjustment operation to adjust the power generation of the fuel cell unit 17 so that the sum of the power generation of the fuel cell unit 17 and the predicted lower limit power generation value follows the load power of the power load 14. As a result, even if the power generation of the solar cell system 12 drops to the predicted lower limit power generation value due to cloud cover, the load power of the power load 14 is expected to be covered by the power generation of the fuel cell unit 23 and the power generation of the solar cell system 12. In other words, even if the power generated by the solar panel 12 decreases due to cloud cover, the amount of electricity purchased from the power grid 1 is suppressed.

[0062] Furthermore, if the sun is not obscured and the power generated by the solar cell device 12 is sufficiently large, the sum of the power generated by the fuel cell device 23 and the power generated by the solar cell device 12 may exceed the load power of the power load 14, and this surplus power may flow back into the power grid 1. However, in this embodiment, the power generated by the fuel cell device 23 is adjusted to be less than the load power of the power load 14, so even if such surplus power occurs, its magnitude will be kept small. In other words, the power generated by the fuel cell device 23 and the power generated by the solar cell device 12 will be consumed as much as possible within the system.

[0063] In this embodiment, when power generation adjustment operation is performed, the power generated by the fuel cell device 23 becomes less than the load power of the power load 14. In other words, when power generation adjustment operation is performed, it means that less heat is generated by the fuel cell device 23. Therefore, when the heat utilization conditions are met (i.e., when most of the generated heat is utilized), when power generation adjustment operation is performed, the amount of heat generated by the fuel cell device 23 decreases, and the operating cost of, for example, the heat source 21 required to generate the reduced amount of heat increases.

[0064] Therefore, the operation control unit 24 may not perform power generation adjustment operation if predetermined heat utilization conditions indicating that the generated heat is in a state where it can be utilized are met, and may perform power generation adjustment operation if the heat utilization conditions are not met. Alternatively, the operation control unit 24 may not perform power generation adjustment operation if the predetermined heat utilization conditions, which indicate that the generated heat is in a state where it can be utilized, are met for a predetermined period of time or longer, and may perform power generation adjustment operation if the heat utilization conditions are not met for a predetermined period of time or longer.

[0065] The heat utilization conditions include, for example, that the temperature of the hot water measured by the temperature sensor T1 is below the set temperature, and that the radiator 20 is not operating to dissipate heat. For example, when heat is being utilized in the heat load unit 22, as hot water is discharged from the hot water storage tank 18 to the heat load unit 22, water is supplied to the bottom of the hot water storage tank 18, and the temperature of the hot water stored in the bottom of the hot water storage tank 18 decreases. As a result, the temperature of the hot water measured by the temperature sensor T1 becomes below the set temperature, for example, and the radiator 20 does not operate to dissipate heat. Therefore, the operation control unit 24 can determine that the heat utilization conditions, which indicate that the generated heat is being utilized, are met if the temperature of the hot water measured by the temperature sensor T1 is below the set temperature, or if the radiator 20 is not operating to dissipate heat.

[0066] As described above, if the operation control unit 24 is configured not to perform power generation adjustment operation when the heat utilization conditions are met, or when the conditions for heat utilization are met for a predetermined period of time or longer, the increase in the operating costs of the heat source unit 21 as described above can be suppressed. On the other hand, if the heat utilization conditions are not met, or when the conditions for heat utilization are not met for a predetermined period of time or longer, it is acceptable for the amount of heat generated by the fuel cell device 23 to decrease, so the operation control unit 24 can perform power generation adjustment operation.

[0067] Next, I will explain specific driving examples 1 and 2.

[0068] [Driving Example 1] Suppose the user checks the weather forecast in the morning and thinks, "It will be sunny until evening, so I'll set the power generation adjustment operation accordingly," and decides that "the amount of PV power generated when it's cloudy can be the same as in the past, 1kW." In other words, the user decides to set the predicted minimum power generation of the solar cell device 12 mentioned above to 1kW.

[0069] In that case, the user inputs the start of power generation adjustment operation to the input reception unit 26, and also inputs the following information to the input reception unit 26, for example. • Start time of power generation adjustment operation (start of the adjustment period): 8:00 • End time of power generation adjustment operation (end of the adjustment period): 16:00 • Predicted minimum value: 1kW • When utilizing waste heat (when heat utilization conditions are met): No power generation adjustment operation is performed.

[0070] In the case of the above derivation example 1, the operation control unit 24 determines, based on the information received by the input reception unit 26, the trend of the predicted lower limit power generation power such that the predicted lower limit power generation power is kept constant at the predicted minimum value of 1 kW, as shown in Figure 2. In addition, the power generation adjustment period during which power generation adjustment operation is performed is between 8:00 and 16:00, as shown in Figure 2.

[0071] Furthermore, during the adjustment period for power generation adjustment operation (8:00 to 16:00), the operation control unit 24 performs power generation adjustment operation if "temperature of hot water measured by temperature sensor T1" > "set temperature," that is, if the heat utilization conditions are not met. Conversely, during the adjustment period for power generation adjustment operation (8:00 to 16:00), the operation control unit 24 does not perform power generation adjustment operation using the above predicted lower limit power generation, but instead performs load following operation if "temperature of hot water measured by temperature sensor T1" ≤ "set temperature," that is, if the heat utilization conditions are met.

[0072] Furthermore, users can also stop the power generation adjustment operation. For example, users can stop the power generation adjustment operation when the weather is no longer sunny, that is, when the situation of suddenly becoming cloudy from sunny conditions no longer occurs. Specifically, users can input an instruction to terminate the power generation adjustment operation to the input reception unit 26. In that case, the operation control unit 24 can stop the ongoing power generation adjustment operation in response to the termination instruction received from the user by the input reception unit 26. After terminating the power generation adjustment operation, the operation control unit 24 will perform load following operation, for example, in which the power generated by the fuel cell unit 17 follows the load power of the power load 14.

[0073] [Driving Example 2] Suppose the user checks the weather forecast in the morning and thinks, "It will be sunny until evening, so I'll set the power generation adjustment operation accordingly," and determines that "the amount of PV power generated on a sunny day is about 5kW." In other words, the user decides to set the predicted maximum power generation of the solar cell device 12 mentioned above to 5kW.

[0074] In that case, the user inputs the start of power generation adjustment operation to the input reception unit 26, and also inputs the following information to the input reception unit 26, for example. • Start time of power generation adjustment operation (start of the adjustment period): 8:00 • End time of power generation adjustment operation (end of the adjustment period): 16:00 • Predicted maximum value: 5kW • When utilizing waste heat (when heat utilization conditions are met): No power generation adjustment operation is performed.

[0075] In the case of the above derivation example 4, the operation control unit 24 determines the predicted minimum value (1kW) by multiplying the predicted maximum value of the power generated by the solar cell device 12 received by the input reception unit 26 by a predetermined coefficient (0.2). Then, based on the reference increase / decrease curve and the predicted minimum value, the operation control unit 24 determines the trend of the predicted lower limit power generation as shown in Figure 5. In addition, the power generation adjustment period during which power generation adjustment operation is performed is between 8:00 and 16:00 as shown in Figure 5.

[0076] Furthermore, during the adjustment period for power generation adjustment operation (8:00 to 16:00), the operation control unit 24 performs power generation adjustment operation if "temperature of hot water measured by temperature sensor T1" > "set temperature," that is, if the heat utilization conditions are not met. Conversely, during the adjustment period for power generation adjustment operation (8:00 to 16:00), the operation control unit 24 does not perform power generation adjustment operation using the above predicted lower limit power generation, but instead performs load following operation if "temperature of hot water measured by temperature sensor T1" ≤ "set temperature," that is, if the heat utilization conditions are met. Furthermore, as in Operation Example 1, users can also choose to discontinue the power generation adjustment operation.

[0077] <Another Embodiment> In the above embodiment, the configuration of the fuel cell device 23 and the power supply system was specifically described, but the configuration can be changed as appropriate. For example, a power generation device can be used that includes an engine and a generator (power generation unit) driven by that engine.

[0078] In the above embodiment, the shape of the reference increase / decrease curve may be adjusted according to the date and the latitude and longitude of the location where the power generation device is installed.

[0079] In the above embodiment, an example was described in which, in power generation adjustment operation, when the target power generation is less than the minimum power generation, the operation control unit 24 adjusts the power generation of the fuel cell unit 17 to the minimum power generation. However, the operation control unit 24 may adjust the power generation of the fuel cell unit 17 to other values. For example, in power generation adjustment operation, if the target power generation (= load power of power load 14 - predicted lower limit power generation) is less than the minimum power generation, the operation control unit 24 may operate the fuel cell unit 17 in an idling state (i.e., a state in which power is not supplied to the power line 11).

[0080] In the above embodiment, specific numerical values ​​were given as examples for the predicted minimum value, predicted maximum value, predetermined coefficient, and time of the power generated by the solar cell device 12. However, these values ​​are provided for illustrative purposes only and can be changed as appropriate.

[0081] The configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Furthermore, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto and can be modified as appropriate without departing from the purpose of the present invention. [Industrial applicability]

[0082] This invention can be used in power generation devices and fuel cell devices that can consume as much of the generated electricity as possible within the country and minimize the amount of electricity purchased from the grid. [Explanation of Symbols]

[0083] 1: Power system 11: Power lines 12: Solar cell device 14: Power load 17: Fuel Cell Section (Power Generation Section) 23: Fuel cell equipment (power generation equipment) 24: Operation Control Unit 26: Input Reception Section

Claims

1. A power generation device comprising a power generation unit connected to a power line connected to a power grid and an operation control unit that controls the operation of the power generation unit, The aforementioned power line is connected to a solar cell device and a power load. It is equipped with an input reception unit that receives information input from users, The operation control unit is configured to derive a predicted lower limit of power generation for the solar cell, based on the predicted minimum power generation of the solar cell received by the input receiving unit, or the predicted minimum power generation obtained by multiplying the predicted maximum power generation of the solar cell received by the input receiving unit by a predetermined coefficient, and to perform a power generation adjustment operation that adjusts the power generation of the power generation unit so that the sum of the power generation of the power generation unit and the predicted lower limit of power generation follows the load power of the power load.

2. The power generation apparatus according to claim 1, wherein the operation control unit derives the predicted minimum value as the predicted lower limit of power generation during the time period in which the power generation adjustment operation is performed.

3. The power generation apparatus according to claim 1, wherein the operation control unit derives the trend of the predicted lower limit of power generation based on a reference increase / decrease curve representing the increase / decrease change in power generation when the power generation of the solar cell increases and decreases between sunrise and sunset, and the predicted minimum value.

4. The power generation apparatus according to any one of claims 1 to 3, wherein the operation control unit performs the power generation adjustment operation during the adjustment target time period received by the input reception unit from the user.

5. The power generation apparatus according to any one of claims 1 to 3, wherein the operation control unit cancels the power generation adjustment operation that is in progress in response to a termination instruction received by the input receiving unit from the user.

6. A fuel cell device that has the functions of a power generation device according to any one of claims 1 to 3, and generates both heat and electricity.

7. The fuel cell apparatus according to claim 6, wherein the operation control unit does not perform the power generation adjustment operation if predetermined heat utilization conditions indicating that the generated heat is in a state where it can be utilized are met, and performs the power generation adjustment operation if the heat utilization conditions are not met.

8. The fuel cell apparatus according to claim 6, wherein the operation control unit does not perform the power generation adjustment operation if a predetermined heat utilization condition indicating that the generated heat is in a state where it is being utilized is met for a predetermined period of time or longer, and performs the power generation adjustment operation if the state where the heat utilization condition is met is not met for a predetermined period of time or longer.

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