Power control method, power control device, and power source system

Abstract

In a power control method of the present disclosure, when power is supplied to a power load of a power consumer from a distributed power source system provided with a photovoltaic power generation device, a fuel cell device, and a power storage device, a value equal to or less than a difference between the actual generated power of the fuel cell device and the total sum of the actual demand power of the power consumer and a chargeable power equal to or less than a maximum charging power of the power storage device is set as a power generation upper limit value of the photovoltaic power generation device.

Description

Power control method, power control device and power supply system

[0001] The present disclosure relates to a power control method, a power control device, and a power supply system.

[0002] Various proposals have been made regarding power control of power supply systems. For example, Patent Document 1 discloses a photovoltaic power generation system including a solar cell, a power conditioner, and a control device, in which the control device acquires power consumption, calculates a predicted value of power consumption after a predetermined time has elapsed from the power consumption amounts at multiple times using a function obtained based on regression analysis, outputs a command value to the power conditioner specifying a power generation amount that will be equal to or less than the predicted value, and the power conditioner controls the power generation amount of the solar cell to be equal to or less than the predicted value based on the command value.

[0003] Patent No. 6792272

[0004] An object of the present disclosure is to provide, as an example, a power control method, a power control device, and a power supply system that can reduce the amount of power that flows back from a distributed power supply system to a power grid more than conventional methods.

[0005] In order to solve the above problem, a power control method according to one aspect of the present disclosure, when supplying power to a power load of a power consumer from a distributed power generation system including a solar power generation device, a fuel cell device, and a power storage device, sets an upper power generation limit value of the solar power generation device to a value less than the difference between the sum of the actual power demand of the power consumer and the chargeable power less than the maximum charging power of the power storage device, and the actual power generation power of the fuel cell device.

[0006] One aspect of the present disclosure is a power control device for a distributed power system that supplies power to a power load of an electric power consumer and includes a solar power generation device, a fuel cell device, and a power storage device, and includes a memory that stores the actual power demand of the electric power consumer, a chargeable power that is less than or equal to the maximum charging power of the power storage device, and the actual power generation power of the fuel cell device, and a controller that sets the power generation upper limit value of the solar power generation device to a value that is less than or equal to the difference between the sum of the actual power demand of the electric power consumer and the chargeable power and the actual power generation power of the fuel cell device.

[0007] A power supply system according to one aspect of the present disclosure includes a fuel cell device, a power storage device, and the above-described power control device.

[0008] The power control method, power control device, and power supply system according to one aspect of the present disclosure have the advantage of being able to reduce the amount of power flowing back from a distributed power supply system to the power grid more than ever before.

[0009] FIG. 1 is a diagram illustrating an example of a power supply system according to a first embodiment. FIG. 2 is a diagram illustrating an example of a distributed power supply system provided in the power supply system according to the first embodiment. FIG. 3 is a diagram illustrating an example of a power control device according to the first embodiment. FIG. 4 is a flowchart illustrating an example of the operation (power control method) of the power control device according to the first embodiment. FIG. 5 is a flowchart illustrating an example of the operation of the power control device (power control method) in a first example of the first embodiment. FIG. 6 is a flowchart illustrating an example of the operation of the power control device (power control method) in a second example of the first embodiment. FIG. 7 is a diagram illustrating an example of a power supply system according to a second embodiment. FIG. 8A is a flowchart illustrating an example of the operation (power control method) of the power control device according to the second embodiment. FIG. 8B is a diagram for explaining an example of the operation of the power control device according to the second embodiment.

[0010] Patent Document 1 describes the control of suppressing reverse power flow from solar cells to the power grid by keeping the amount of power generated by the solar cells below the predicted value of power consumption, but does not consider control of suppressing reverse power flow from a distributed power generation system including a solar power generation device, a fuel cell device, and a storage device to the power grid.

[0011] Therefore, in the power control method of the first aspect of the present disclosure, when power is supplied to a power load of a power consumer from a distributed power system including a solar power generation device, a fuel cell device, and a power storage device, the power generation upper limit value of the solar power generation device is set to a value less than the difference between the sum of the actual power demand of the power consumer and the chargeable power less than the maximum charging power of the power storage device and the actual power generation power of the fuel cell device.

[0012] According to the above, the power control method of this aspect can reduce the amount of power that flows back from the distributed power system to the power grid more than ever before.

[0013] Specifically, the difference between the sum of the actual power demand of the power consumer and the chargeable power equal to or less than the maximum charging power of the power storage device (hereinafter referred to as the chargeable power of the power storage device) and the actual power generated by the fuel cell device corresponds to the power generated by the photovoltaic power generation device that can be used to supply power to the power load and charge the power storage device. Therefore, the power control method of this aspect sets the power generation upper limit of the photovoltaic power generation device to a value equal to or less than the difference between the sum of the actual power demand of the power consumer and the chargeable power of the power storage device and the actual power generated by the fuel cell device, thereby making it possible to appropriately suppress the power generated by the photovoltaic power generation device from flowing back into the power grid, compared to when the power generation upper limit of the photovoltaic power generation device is not set.

[0014] A second aspect of the power control method of the present disclosure may be such that, in the power control method of the first aspect, when the charging rate of the storage device is equal to or greater than a first threshold value that is smaller than 100%, the chargeable power of the storage device is reduced and the above-mentioned difference is calculated.

[0015] When the charge rate of the power storage device is equal to or higher than a first threshold value that is smaller than 100%, the power storage device is likely to be fully charged by power supply from the solar power generation device to the power storage device. When the power storage device is fully charged, the solar power generation device cannot supply further power to the power storage device, and the power generated by the solar power generation device is likely to flow back to the power grid.

[0016] Therefore, in the power control method of this aspect, when the charging rate of the power storage device is equal to or higher than a first threshold, the chargeable power of the power storage device is reduced, and the difference between the sum of the actual power demand of the power consumer and the chargeable power after the reduction and the actual power generation of the fuel cell device is calculated. As a result, by setting a value equal to or lower than this difference as the power generation upper limit of the photovoltaic power generation device, it is possible to appropriately suppress the power generated by the photovoltaic power generation device from flowing back into the power grid more effectively than when the chargeable power is not reduced.

[0017] A power control method according to a third aspect of the present disclosure may be the power control method according to the second aspect, wherein the value of the chargeable power of the power storage device after the chargeable power of the power storage device is reduced may be zero.

[0018] According to the above, the power control method of this aspect sets the power generation upper limit of the photovoltaic power generation device to a value equal to or less than the difference between the actual power demand of the power consumer and the actual power generation power of the fuel cell device when the chargeable power after the reduction is 0. As a result, the power control method of this aspect can appropriately suppress the power generated by the photovoltaic power generation device from flowing back into the power grid, compared to when the chargeable power is not set to 0.

[0019] A fourth aspect of the power control method of the present disclosure may be such that, in the power control method of the second or third aspect, when the charging rate of the power storage device is equal to or lower than a second threshold value that is lower than the first threshold value, the chargeable power after the reduction may be returned to the value before the reduction, and the above-mentioned difference may be calculated.

[0020] If the timing at which the chargeable power is returned to the value before the reduction is when the charge rate of the power storage device is equal to or lower than a second threshold that is lower than the first threshold, the possibility that the charge rate of the power storage device will again exceed the first threshold in a short period of time is reduced. In other words, it is possible to prevent the occurrence of an event in which the suppression and release of the power generation suppression of the photovoltaic power generation device are repeated in a short period of time.

[0021] Furthermore, in the power control method of this aspect, when the charging rate of the power storage device is equal to or lower than a second threshold, the chargeable power after the reduction is restored to the value before the reduction, and the difference between the actual power demand of the power consumer and the sum of the chargeable power and the actual power generation power of the fuel cell device is calculated. Then, the power control method of this aspect sets a value equal to or lower than this difference as the power generation upper limit value of the solar power generation device, thereby enabling effective utilization of the power generation power of the solar power generation device. In other words, the power generation upper limit value of the solar power generation device calculated based on the chargeable power before the reduction is higher than the power generation upper limit value of the solar power generation device calculated based on the chargeable power after the reduction. Therefore, the higher the power generation upper limit value of the solar power generation device, the less likely the output of the solar power generation device will be limited to the power generation upper limit value, allowing effective utilization of the power generation power of the solar power generation device.

[0022] A fifth aspect of the present disclosure is a power control device for a distributed power system that supplies power to a power load of an electric power consumer and includes a solar power generation device, a fuel cell device, and a power storage device, and includes a memory that stores the actual power demand of the electric power consumer, the chargeable power of the power storage device, and the actual power generation power of the fuel cell device, and a controller that sets the power generation upper limit value of the solar power generation device to a value that is less than or equal to the difference between the sum of the actual power demand of the electric power consumer and the chargeable power and the actual power generation power of the fuel cell device.

[0023] With this configuration, the power control device of this aspect can reduce the amount of power that flows back from the distributed power system to the power grid more than ever before. Note that the details of the effects achieved by the power control device of this aspect are similar to the effects achieved by the power control method of the first aspect, and therefore will not be described here.

[0024] A power supply system according to a sixth aspect of the present disclosure includes a solar power generation device, a fuel cell device, a power storage device, and the power control device according to the fifth aspect.

[0025] With this configuration, the power supply system of this aspect can reduce the amount of power that flows back from the distributed power supply system to the power grid more than in the past. Note that the details of the effects of the power supply system of this aspect are similar to those of the power control method of the first aspect, and therefore will not be described here.

[0026] Specific examples of the above-described aspects of the present disclosure will be described below with reference to the accompanying drawings. Each of the specific examples described below is an example of the above-described aspects of the present disclosure. Therefore, unless otherwise stated in the claims, the shapes, numerical values, components, arrangement positions and connection forms of the components shown below do not limit the scope of the claims.

[0027] Furthermore, among the components described below, components that are not described in the independent claims that represent the highest concept of the present disclosure are described as optional components. Furthermore, in the drawings, components with the same reference numerals may not be described in detail. The drawings are schematic illustrations of each component for ease of understanding, and the shapes, dimensional ratios, and the like may not be accurately depicted.

[0028] Furthermore, in the operation of the apparatus, the order of steps may be changed or known steps may be added as necessary.

[0029] (First embodiment) [Device configuration] Fig. 1 is a diagram illustrating an example of a power supply system according to a first embodiment. Fig. 2 is a diagram illustrating an example of a distributed power supply system provided in the power supply system according to the first embodiment. Fig. 3 is a diagram illustrating an example of a power control device according to the first embodiment.

[0030] As shown in FIG. 1 , a power supply system 10 of this embodiment includes a power control device 20 and a distributed power supply system 30 .

[0031] In the example shown in FIG. 2, the distributed power system 30 includes a fuel cell device 31, a power storage device 32, and a solar power generation device 33, which supply power to a power load 40 of a power consumer.

[0032] An "electricity consumer" is an entity that owns an electric power load 40 that receives the service of supplying electric power generated by the power supply system 10. Examples of an "electricity consumer" include, but are not limited to, a factory, a store, or an ordinary household.

[0033] The power supply system 10 may be, for example, a system that supplies a large amount of power to a power grid. In this case, the fuel cell device 31, the solar power generation device 33, and the power storage device 32 each include a fuel cell unit group consisting of a plurality of fuel cell units including a fuel cell stack, a solar cell group consisting of a plurality of solar cells including a solar panel, and a storage battery unit group consisting of a plurality of storage battery units, and the detailed configuration of such a power supply system 10 will be described in a second embodiment.

[0034] The power storage device 32 is a device that stores power generated by the fuel cell device 31 and the solar power generation device 33 or power received from the power grid under the control of the power control device 20. The power stored in the power storage device 32 may be discharged to the power load 40 of the power consumer or to the power grid under the control of the power control device 20. The power storage device 32 can transmit, at an appropriate timing, information such as a state of charge (SOC) that indicates the remaining amount of power (amount of charge) stored in the power storage device 32. The power storage device 32 can be, for example, a well-known secondary battery, but is not limited to this.

[0035] The fuel cell device 31 generates electricity using hydrogen supplied from a hydrogen supply source (not shown) under the control of the power control device 20. The power generated by the fuel cell device 31 is supplied to a power load 40, a power grid, or a power storage device 32. A well-known device can be used as the fuel cell device 31. An example of the hydrogen supply source is a hydrogen storage tank, but is not limited to this.

[0036] The solar power generation device 33 is an electric power device that converts light energy from sunlight into electric power under the control of the power control device 20. The electric power generated by the solar power generation device 33 is supplied to the electric power load 40, the electric power system, or the electric storage device 32. A well-known device can be used as the solar power generation device 33.

[0037] As shown in FIG. 3 , the power control device 20 includes a storage unit 21 and a controller 22 .

[0038] The memory 21 is a memory for storing the actual power demand of the power consumer, the chargeable power less than the maximum charging power of the storage device 32 (hereinafter referred to as the chargeable power of the storage device 32), and the actual generated power of the fuel cell device 31.

[0039] Here, the "actual demand power of the power consumer" refers to the power consumed by the power load 40, and may be the latest data stored in the memory 21, or the moving average value of the most recent data sampled at an appropriate sampling period and stored in the memory 21.

[0040] The "actual power generated by the fuel cell device 31" refers to the rated output of the fuel cell device 31 or a predetermined output less than the rated output, and may be the latest data stored in the memory 21, or the moving average value of the most recent data sampled at an appropriate sampling period and stored in the memory 21.

[0041] The "maximum charging power of the power storage device 32" is the charging capacity (kW) of the power storage device 32 that is determined based on the specifications and usage conditions of the power storage device 32, etc. The "maximum charging power of the power storage device 32" may be transmitted from the power storage device 32 to the power control device 20 at an appropriate timing. The "chargeable power of the power storage device 32" may be, for example, the maximum charging power, or a value less than the maximum charging power that can be specified by a user or the like. The user includes direct or indirect users of the power control device 20. A direct user of the power control device 20 is, for example, an administrator of the power control device 20. An indirect user of the power control device 20 may be, for example, an owner of the power supply system 10. Such an owner may be the power consumer or a power generation company that supplies power to power consumers using the power supply system 10.

[0042] The controller 22 sets the upper limit of power generation of the solar power generation device 33 to a value equal to or less than the difference between the sum of the actual power demand of the power consumer and the chargeable power of the power storage device 32 and the actual power generation power of the fuel cell device 31.

[0043] The controller 22 may be any device having a control function, and includes an arithmetic processing unit (not shown) and a storage unit (not shown) that stores a control program. The arithmetic processing unit reads and executes the control program stored in the storage unit, thereby performing predetermined control in the controller 22. An example of the arithmetic processing unit is a microprocessor. An example of the storage unit is a memory.

[0044] [Operation] FIG. 4 is a flowchart showing an example of the operation (power control method) of the power control device of the first embodiment.

[0045] The following operations may be performed, for example, by the arithmetic processing unit of the controller 22 of the power control device 20 reading out a control program from the storage unit of the controller 22. However, it is not necessarily required that the following operations be performed by the controller 22. An operator may perform some of the operations. In the following example, a case where the operations are controlled by the controller 22 will be described.

[0046] First, in step S1, power is supplied from the distributed power system 30 to the power load 40 of the power consumer.

[0047] Next, in step S2, the difference between the sum of the actual power demand of the power consumer and the chargeable power of the power storage device 32 and the actual power generated by the fuel cell device 31 is calculated.

[0048] Next, in step S3, a value equal to or less than the difference in step S2 is set as the power generation upper limit of the solar power generation device 33. As a result, when the power generated by the solar power generation device 33 exceeds the power generation upper limit of the solar power generation device 33 due to weather conditions, for example, output control of the solar power generation device 33 is executed so that the output of the solar power generation device 33 is limited to the power generation upper limit. Conversely, unless the power generated by the solar power generation device 33 exceeds the power generation upper limit of the solar power generation device 33, output control of the solar power generation device 33 is not executed.

[0049] According to the present embodiment described above, the amount of power flowing back from the distributed power system 30 to the power grid can be reduced more than in the past.

[0050] Specifically, the difference between the sum of the actual power demand of the power consumer and the chargeable power of the power storage device 32 and the actual power generated by the fuel cell device 31 corresponds to the power generated by the solar power generation device 33 that can be used to supply power to the power load 40 and charge the power storage device 32. Therefore, in this embodiment, by setting the power generation upper limit of the solar power generation device 33 to a value that is equal to or less than the difference between the sum of the actual power demand of the power consumer and the chargeable power of the power storage device 32 and the actual power generated by the fuel cell device 31, it is possible to appropriately prevent the power generated by the solar power generation device 33 from flowing back into the power grid, compared to when the power generation upper limit of the solar power generation device 33 is not set.

[0051] First Example The power control method of this example is the same as that of the first embodiment, except for the control details of the controller 22, which will be described below.

[0052] FIG. 5 is a flowchart showing an example of the operation of the power control device (power control method) in the first example of the first embodiment.

[0053] The following operations may be performed, for example, by the arithmetic processing unit of the controller 22 (see FIG. 3 ) of the power control device 20 reading out a control program from the storage unit of the controller 22. However, it is not essential that the following operations be performed by the controller 22. An operator may perform some of the operations. In the following example, a case where the operations are controlled by the controller 22 will be described.

[0054] Note that steps S1 and S2 in FIG. 5 are similar to steps S1 and S2 in FIG. 4, respectively, and therefore will not be described.

[0055] In step S4, it is determined whether the charging rate SOC of the power storage device 32 is equal to or higher than a threshold value A.

[0056] Here, the "threshold A" in step S4 is set to an appropriate charging rate SOC of the power storage device 32 that is smaller than 100%. The "threshold A" can be, for example, approximately 90%, but is not limited to this. The "threshold A" is an example of the "first threshold" in the present disclosure.

[0057] When the charging rate SOC of the storage device 32 is equal to or higher than the threshold value A ("Yes" in step S4), the chargeable power of the storage device 32 is reduced in step S5, and the difference between the sum of the actual power demand of the power consumer and the chargeable power after the reduction and the actual power generated by the fuel cell device 31 is calculated, and the process proceeds to the next step S3A.

[0058] Here, the "chargeable power after reduction" in step S5 may be a value equal to or greater than 0 that can be designated by a user or the like. The "chargeable power after reduction" may be, for example, 0, but is not limited to this.

[0059] When the charging rate SOC of the power storage device 32 is not equal to or higher than the threshold value A ("No" in step S4), step S5 is bypassed and the process proceeds to the next step S3A.

[0060] In step S3A, a value equal to or less than the difference in step S2 or a value equal to or less than the difference in step S5 is set as the power generation upper limit of the photovoltaic power generation device 33. Note that in the latter case, when the "chargeable power after reduction" in step S5 is 0, a value equal to or less than the difference between the actual power demand of the power consumer and the actual power generation power of the fuel cell device 31 is set as the power generation upper limit of the photovoltaic power generation device 33. As a result, when the power generation power of the photovoltaic power generation device 33 exceeds the power generation upper limit of the photovoltaic power generation device 33 due to weather conditions, for example, output control of the photovoltaic power generation device 33 is executed so that the output of the photovoltaic power generation device 33 is limited to the power generation upper limit. Conversely, unless the power generation power of the photovoltaic power generation device 33 exceeds the power generation upper limit of the photovoltaic power generation device 33, output control of the photovoltaic power generation device 33 is not executed.

[0061] When the charging rate SOC of the power storage device 32 is equal to or higher than the threshold value A, there is a high possibility that the power storage device 32 will be fully charged by power supply from the solar power generation device 33 to the power storage device 32. When the power storage device 32 is fully charged, the solar power generation device 33 cannot supply any more power to the power storage device 32, and the power generated by the solar power generation device 33 is likely to flow back to the power grid.

[0062] Therefore, according to this embodiment, when the charging rate SOC of the power storage device 32 is equal to or higher than threshold A, the chargeable power of the power storage device 32 is reduced, and the difference between the sum of the actual power demand of the power consumer and the chargeable power after the reduction is calculated, and the actual power generated by the fuel cell device 31. As a result, this embodiment sets a value equal to or less than this difference as the power generation upper limit of the solar power generation device 33, thereby making it possible to appropriately suppress the power generated by the solar power generation device 33 from flowing back into the power grid more effectively than when the chargeable power is not reduced.

[0063] Furthermore, according to this embodiment, when the chargeable power after the reduction is 0, a value equal to or less than the difference between the actual power demand of the power consumer and the actual power generated by the fuel cell device 31 is set as the power generation upper limit of the photovoltaic power generation device 33. As a result, this embodiment can appropriately suppress the power generated by the photovoltaic power generation device 33 from flowing back into the power grid, compared to when the chargeable power is not set to 0.

[0064] The power control method, power control device 20, and power supply system 10 of this embodiment may be the same as those of the first embodiment except for the above-mentioned features.

[0065] Second Example The power control method of this example is the same as that of the first embodiment or the first example of the first embodiment, except for the control content of the controller 22, which will be described below.

[0066] FIG. 6 is a flowchart showing an example of the operation of the power control device (power control method) in the second example of the first embodiment.

[0067] The following operations may be performed, for example, by the arithmetic processing unit of the controller 22 (see FIG. 3 ) of the power control device 20 reading out a control program from the storage unit of the controller 22. However, it is not essential that the following operations be performed by the controller 22. An operator may perform some of the operations. In the following example, a case where the operations are controlled by the controller 22 will be described.

[0068] Note that steps S1 and S2 in Fig. 6 are similar to steps S1 and S2 in Fig. 4, respectively, and therefore will not be described here. Steps S4 and S5 in Fig. 6 are similar to steps S4 and S5 in Fig. 5, respectively, except that when the charging rate SOC of power storage device 32 is not equal to or lower than threshold A (in the case of "No" in step S4), steps S5 to S7 are bypassed and the process proceeds to step S3B, and therefore will not be described here.

[0069] In step S6, it is determined whether the charging rate SOC of the power storage device 32 is equal to or lower than a threshold value B.

[0070] Here, the "threshold B" in step S6 is set to an appropriate charging rate SOC of the power storage device 32 that is smaller than the threshold A. The "threshold B" can be, for example, approximately 85%, but is not limited to this. The "threshold B" is an example of the "second threshold" of the present disclosure.

[0071] When the charging rate SOC of the storage device 32 is below threshold B ("Yes" in step S6), in step S7, the "chargeable power after reduction" in step S5 is returned to the value before reduction, and the difference between the actual demand power of the power consumer and the sum of the chargeable power and the actual generated power of the fuel cell device 31 is calculated, and the process proceeds to the next step S3B.

[0072] When the charging rate SOC of the power storage device 32 is not equal to or lower than the threshold value B ("No" in step S6), step S7 is bypassed and the process proceeds to the next step S3B.

[0073] In step S3B, a value equal to or less than the difference in step S2, a value equal to or less than the difference in step S5, or a value equal to or less than the difference in step S7 is set as the power generation upper limit of the solar power generation device 33. As a result, when the power generation power of the solar power generation device 33 exceeds the power generation upper limit of the solar power generation device 33 due to weather conditions, for example, output control of the solar power generation device 33 is executed so that the output of the solar power generation device 33 is limited to the power generation upper limit. Conversely, unless the power generation power of the solar power generation device 33 exceeds the power generation upper limit of the solar power generation device 33, output control of the solar power generation device 33 is not executed.

[0074] If the timing at which the chargeable voltage is returned to the value before the decrease is when the charging rate SOC of the power storage device 32 is equal to or lower than the threshold value B, the possibility that the charging rate SOC of the power storage device 32 will again become equal to or higher than the threshold value A in a short period of time is reduced. In other words, it is possible to prevent the occurrence of an event in which the suppression and release of the power generation suppression of the solar power generation device 33 are repeated in a short period of time.

[0075] Furthermore, according to this embodiment, when the state of charge SOC of the power storage device 32 is equal to or lower than threshold B, the chargeable power after the reduction is returned to the value before the reduction, and the difference between the actual power demand of the power consumer, the sum of the chargeable power, and the actual power generation power of the fuel cell device is calculated. Then, in this embodiment, a value equal to or lower than this difference is set as the power generation upper limit of the solar power generation device 33, thereby enabling effective utilization of the power generated by the solar power generation device 33. In other words, the power generation upper limit of the solar power generation device 33 calculated based on the chargeable power before the reduction is higher than the power generation upper limit of the solar power generation device 33 calculated based on the chargeable power after the reduction. Therefore, the higher the power generation upper limit of the solar power generation device 33, the less likely the output of the solar power generation device 33 will be limited to the power generation upper limit, allowing effective utilization of the power generated by the solar power generation device 33. As a result, the power generation self-sufficiency rate of the power supply system 10 can be improved.

[0076] Other than the above-mentioned features, the power control method, power control device 20, and power supply system 10 of this embodiment may be similar to those of the first embodiment or the first example of the first embodiment.

[0077] Second Embodiment [Device Configuration] Fig. 7 is a diagram showing an example of a power supply system according to a second embodiment. In Fig. 7, for convenience, solid lines and dashed lines respectively indicate paths through which power is transmitted and paths through which signals are transmitted.

[0078] As shown in FIG. 7, the power supply system 10 of this embodiment includes a power control device 20, a fuel cell device 31, a power storage device 32, a solar power generation device 33, and control devices 50A to 50C.

[0079] Here, the internal configuration of the power control device 20 is the same as that of the first embodiment, and therefore a detailed description thereof will be omitted.

[0080] In the example shown in Figure 7, the fuel cell device 31 includes a fuel cell unit group consisting of a plurality of fuel cell units. The fuel cell unit group is divided into a plurality of groups, and the fuel cell units in each group are connected to the power grid via a power conditioner (PCS) and a power meter. The power meter is connected to the power control device 20 via a communications network. The number of fuel cell units in each group is set to an appropriate value depending on the output specifications of the power supply system 10, etc.

[0081] Although not shown, each of these fuel cell units is composed of auxiliary equipment such as a fuel cell stack, pumps, and valves, as well as a control device that controls the operation of these devices. If a control device is not provided within the fuel cell unit, the operation of the above-mentioned devices may be directly controlled by the control device 50A.

[0082] The photovoltaic power generation device 33 includes a solar cell group consisting of a plurality of solar cells including a solar panel. The solar cell group is divided into a plurality of groups each of which is connected to the power grid via a power conditioner (PCS) and a power meter. The power meter is connected to the power control device 20 via a communication network. The number of solar cells in each group is set to an appropriate value depending on the output specifications of the power supply system 10, etc.

[0083] The power storage device 32 includes a group of storage battery units each consisting of a plurality of storage battery units. The group of storage battery units is divided into a plurality of groups, and the plurality of storage battery units in each group are connected to the power grid via a power conditioner (PCS) and a power meter. The power meter is connected to the power control device 20 via a communication network. The number of storage battery units in each group is set to an appropriate value depending on the output specifications of the power supply system 10, etc.

[0084] Furthermore, the fuel cell device 31, the power storage device 32, and the solar power generation device 33 are connected in parallel to one another via a power grid, and are also connected to a power load 40 of a power consumer via a power meter. This power meter is connected to the power control device 20 via a communication network.

[0085] However, the above configuration of the power supply system 10 is merely an example and is not limited to this example. For example, the fuel cell unit group may be grouped by a single group of multiple fuel cell units, or by a single fuel cell unit in each group. The solar cell group may be grouped by a single group of multiple solar cells, or by a single solar cell in each group. The storage battery unit group may be grouped by a single group of multiple storage battery units, or by a single storage battery unit in each group.

[0086] The control devices 50A to 50C are provided corresponding to the fuel cell device 31, the power storage device 32, and the solar power generation device 33, respectively, and are connected to the power control device 20 via a communication network.

[0087] For example, the control device 50A controls the output of each of these fuel cell units via a communication network to enable efficient operation of the fuel cell units (e.g., optimizing their lifespans). The control device 50B may also control a power conditioner (PCS) via the communication network to control the charging and discharging power of the power storage device 32. The control device 50C may also control the power conditioner (PCS) via the communication network to control the output of the photovoltaic power generation device 33, or may use the power conditioner (PCS) to disconnect or connect a desired number of solar cells to or from the power grid.

[0088] However, the above is merely an example and is not limiting. For example, the controller 22 (see FIG. 3) of the power control device 20 may directly control the operation of the devices corresponding to the control devices 50A to 50C, without going through the control devices 50A to 50C. Furthermore, the power control device 20 may be integrated with the control devices 50A to 50C, in other words, equipped with the control functions of the control devices 50A to 50C, and directly control the operation of the devices corresponding to the control devices 50A to 50C.

[0089] The control devices 50A to 50C may be any device that has a control function and includes a processing unit (not shown), a storage unit that stores a control program, and a communication device. The processing unit reads and executes the control program stored in the storage unit, thereby performing predetermined control in the control devices 50A to 50C. An example of the processing unit is a microprocessor. An example of the storage unit is a memory.

[0090] [Operation] Fig. 8A is a flowchart showing an example of the operation (power control method) of the power control device of the second embodiment. Fig. 8B is a diagram for explaining an example of the operation of the power control device of the second embodiment.

[0091] The following operations may be performed, for example, by the arithmetic processing unit of the controller 22 (see FIG. 3 ) of the power control device 20 reading out a control program from the storage unit of the controller 22. However, it is not essential that the following operations be performed by the controller 22. An operator may perform some of the operations. In the following example, a case where the operations are controlled by the controller 22 will be described.

[0092] First, in step S11, the latest generated power FC of the fuel cell device 31, the latest state of charge SOC of the power storage device 32, the chargeable power BC of the power storage device 32, and the power demand D during the sampling period are obtained from the power database. Here, the "sampling period" may be, for example, about 10 minutes, but is not limited to this.

[0093] Then, in step S12, the moving average value D of the power demand D during the sampling period is calculated. ave is calculated.

[0094] In step S13, it is determined whether the charging rate SOC of the power storage device 32 is equal to or higher than a threshold value A.

[0095] Here, the "threshold A" in step S13 is set to an appropriate charging rate SOC of the power storage device 32 that is smaller than 100%. The "threshold A" can be, for example, approximately 90%, but is not limited to this. The "threshold A" is an example of the "first threshold" in the present disclosure.

[0096] When the charging rate SOC of the power storage device 32 is equal to or higher than the threshold value A ("Yes" in step S13), the chargeable power BC of the power storage device 32 is set to 0 in step S14, and the process proceeds to the next determination step S15.

[0097] When the charging rate SOC of the power storage device 32 is not equal to or higher than the threshold value A ("No" in step S13), steps S14 to S16 are bypassed and the process proceeds to step S17.

[0098] In step S15, it is determined whether the charging rate SOC of the power storage device 32 is equal to or lower than a threshold value B.

[0099] Here, the "threshold B" in step S15 is set to an appropriate charging rate SOC of the power storage device 32 that is smaller than the threshold A. The "threshold B" can be, for example, approximately 85%, but is not limited to this. The "threshold B" is an example of the "second threshold" of the present disclosure.

[0100] When the charging rate SOC of the power storage device 32 is equal to or lower than the threshold value B ("Yes" in step S15), the chargeable power BC of the power storage device 32 is returned from 0 to its original value in step S16, and the process proceeds to step S17.

[0101] When the charging rate SOC of the power storage device 32 is not equal to or lower than the threshold value B ("No" in step S15), step S16 is bypassed and the process proceeds to step S17.

[0102] In step S17, the power generation upper limit value PV of the solar power generation device 33 is calculated. limit is set by the following equation (1): limit = (D ave +BC)-FC...(1)

[0103] For example, as shown in the left diagram of FIG. 8B , when the charging rate SOC of the power storage device 32 is equal to or higher than the threshold A, the chargeable power BC of the power storage device 32 is set to 0, and therefore the power generation upper limit value PV of the solar power generation device 33 is set to 0. limit is the area corresponding to the shaded area in FIG. ave -FC).

[0104] Then, the power generation upper limit value PV of the solar power generation device 33 limit (=D ave −FC) is instructed to the control device 50C of the photovoltaic power generation device 33. As a result, the control device 50C controls the output of the photovoltaic power generation device 33 to the power generation upper limit value PV limit The power conditioner (PCS) controls the output of the photovoltaic power generation device 33 so that the output is limited to the above.

[0105] Furthermore, for example, as shown in the right diagram of FIG. 8B, when the charging rate SOC of the power storage device 32 is equal to or lower than the threshold value B, the chargeable power BC of the power storage device 32 is restored, and therefore the power generation upper limit value PV of the solar power generation device 33 limit is the area corresponding to the shaded area in FIG. ave +BC-FC).

[0106] Then, the power generation upper limit value PV of the solar power generation device 33 limit (=D ave +BC-FC) is commanded to the control device 50C of the solar power generation device 33. As a result, the control device 50C controls the output of the solar power generation device 33 to the power generation upper limit value PV limit The power conditioner (PCS) controls the output of the photovoltaic power generation device 33 so that the output is limited to the above.

[0107] The effects of the power control method, power control device 20, and power supply system 10 of this embodiment can be easily understood from the effects described in the first embodiment, and therefore a description thereof will be omitted.

[0108] Other than the above-mentioned features, the power control method, power control device 20, and power supply system 10 of this embodiment may be the same as those of the first embodiment and any of the first and second examples of the first embodiment.

[0109] (Modification) The output control of the photovoltaic power generation device 33 by the control device 50C is not limited to the above. For example, the control device 50C may control the output of the photovoltaic power generation device 33 by using a power conditioner (PCS) to disconnect or connect a desired number of solar cells to the power grid. In other words, when the outputs from the multiple power conditioners (PCS) to the power grid are the same, the power generation upper limit value PV of the photovoltaic power generation device 33 may be controlled by the control device 50C. limit From this, the number of power conditioners (PCS) that should be disconnected from or connected in parallel to the power grid can be known.

[0110] As a result, the control device 50C determines whether the output of the solar power generation device 33 is greater than the power generation upper limit value PV limit In order to prevent the power consumption from exceeding 100 W, a desired number of solar cells can be disconnected from or connected in parallel to the power grid using a power conditioner (PCS).

[0111] Other than the above features, the power control method, power control device 20, and power supply system 10 of this modified example may be the same as any of the first embodiment, the first to second examples of the first embodiment, and the second embodiment.

[0112] The first embodiment, the first example to the second example of the first embodiment, the second embodiment, and the modified example of the second embodiment may be combined with each other as long as they do not exclude each other. From the above description, many improvements and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present disclosure. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present disclosure.

[0113] An aspect of the present disclosure can be used in a power control method, a power control device, and a power supply system that can reduce the amount of power that flows back from a distributed power supply system to a power grid more than ever before.

[0114] 10: Power supply system 20: Power control device 21: Storage device 22: Controller 30: Distributed power supply system 31: Fuel cell device 32: Power storage device 33: Photovoltaic power generation device 40: Power load 50A: Control device 50B: Control device 50C: Control device A: Threshold value B: Threshold value

Claims

1. A power control method, when supplying power to a power load of an electric power consumer from a distributed power source system equipped with a solar power generation device, a fuel cell device, and a power storage device, the power generation upper limit value of the solar power generation device is set to a value less than the difference between the sum of the actual power demand of the electric power consumer and the chargeable power less than the maximum charging power of the power storage device, and the actual power generation power of the fuel cell device.

2. The power control method according to claim 1, further comprising the steps of: reducing the chargeable power and calculating the difference when the charging rate of the power storage device is equal to or higher than a first threshold value that is smaller than 100%.

3. The power control method according to claim 2, wherein the value of the chargeable power after the reduction is 0.

4. A power control method as described in claim 2 or 3, wherein when the charging rate of the storage device is equal to or lower than a second threshold value which is smaller than the first threshold value, the chargeable power after the reduction is returned to the value before the reduction, and the difference is calculated.

5. A power control device for a distributed power system equipped with a solar power generation device, a fuel cell device and a power storage device that supplies power to a power load of an electric power consumer, the power control device comprising: a memory that stores the actual power demand of the electric power consumer, a chargeable power that is equal to or less than the maximum charging power of the power storage device, and the actual power generation of the fuel cell device; and a controller that sets a power generation upper limit value of the solar power generation device to a value that is equal to or less than the difference between the sum of the actual power demand of the electric power consumer and the chargeable power and the actual power generation of the fuel cell device.

6. A power supply system comprising: a solar power generation device; a fuel cell device; a power storage device; and the power control device according to claim 5.

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