JP2021158809A - Power supply system - Google Patents

Abstract

To provide a power supply system capable of increasing self-consumption of power generated by a power generation unit.SOLUTION: A power supply system comprises: a photovoltaic power generation unit 11 capable of generating power using natural energy; a fuel cell 30 that is capable of generating power using fuel and stores heat generated at the time of generating power; and an EMS 60 for controlling operation of the fuel cell 30. The EMS 60 predicts surplus power by which power generated by the photovoltaic power generation unit 11 exceeds a power demand and, when it is predicted that a time zone in which the surplus power is greater than a predetermined value (β) exists (Yes in a step S11), instructs the fuel cell 30 to generate power in a time zone other than the time zone in which surplus power is to be generated (step S12).SELECTED DRAWING: Figure 2

Description

The present invention relates to a technique of a power supply system including a power generation unit and a fuel cell.

Conventionally, the technology of a power supply system including a power generation unit and a fuel cell has been known. For example, as described in Patent Document 1.

Patent Document 1 describes a solar cell that generates electricity using sunlight, a fuel cell that can generate electricity using a fuel such as hydrogen, and a fuel cell that can boil water using exhaust heat generated during power generation. A power supply system including a storage battery capable of charging and discharging is described. In the power supply system, the power generated by the solar cell and the power generated by the fuel cell can be supplied to the domestic load. In addition, the electric power generated by the solar cell can be charged to the storage battery, and the electric power charged in the storage battery can be supplied to the household load. Further, if appropriate, the surplus power (surplus power) of the power generated by the photovoltaic power generation unit can be sold (reverse power flow to a commercial power source).

However, in recent years, the unit price of electricity generated by the photovoltaic power generation unit has tended to decrease, and may be lower than the unit price of midnight electricity. Therefore, it is desired to consume the electric power generated by the photovoltaic power generation unit in the home.

Japanese Unexamined Patent Publication No. 2016-48992

The present invention has been made in view of the above circumstances, and the problem to be solved is to provide a power supply system capable of improving the self-consumption of the power generated by the power generation unit. ..

The problem to be solved by the present invention is as described above, and next, the means for solving this problem will be described.

That is, in claim 1, the operation of a power generation unit capable of generating power using natural energy, a fuel cell capable of generating power using fuel and storing heat generated during power generation, and the fuel cell is controlled. A control unit is provided, and the control unit predicts surplus power generated with respect to the power demand among the power generated by the power generation unit, and there is a time zone in which the surplus power is larger than a predetermined value. When predicted, the fuel cell is instructed to generate electricity in a time zone other than the time zone in which the surplus power is generated.

In claim 2, when the control unit predicts that there is a time zone in which the surplus power is greater than a predetermined value, a time zone other than the time zone in which the amount of power purchased from the grid power source is less than the predetermined value. Is instructed to generate electricity.

In claim 3, when it is predicted that there is no time zone in which the surplus power exceeds a predetermined value, the control unit instructs the fuel cell to generate power in a time zone other than the midnight power time zone. It is something to do.

The fourth aspect of the present invention includes a storage battery capable of charging and discharging electric power, and the control unit starts power generation by the power generation unit when it is predicted that the surplus electric power is larger than the storage capacity of the storage battery. The storage battery is charged with midnight power by the amount of power demand up to the time.

The fifth aspect of the present invention includes a storage battery capable of charging and discharging electric power, and the control unit fully charges the storage battery with midnight electric power when it is predicted that the surplus electric power is smaller than the storage capacity of the storage battery. It is a thing.

As the effect of the present invention, the following effects are exhibited.

In claim 1, it is possible to improve the self-consumption of the electric power generated by the power generation unit.

In claim 2, the power generation efficiency of the fuel cell can be maintained.

In claim 3, when the midnight electricity is lower than the power generation cost of the fuel cell, the utility cost can be reduced.

According to the fourth aspect, it is possible to increase the charge amount of the surplus electric power to the storage battery while supplying the electric power until the time when the power generation starts by the power generation unit with the midnight electric power.

In claim 5, the utility cost can be reduced.

The block diagram which showed the structure of the power supply system which concerns on one Embodiment of this invention. A flowchart showing plan control. A flowchart showing execution control. The figure which showed the power consumption, PV power generation power, etc. before adjusting the power generation time of a fuel cell. The figure which showed the power consumption, PV power generation power, etc. after adjusting the power generation time of a fuel cell.

Hereinafter, the power supply system 1 according to the embodiment of the present invention will be described with reference to FIG. In this specification, the "upstream side" and the "downstream side" are based on the power supply direction from the system power supply K.

The power supply system 1 shown in FIG. 1 supplies the power from the system power supply K and the generated power to the load H. The electric power supply system 1 is provided in a house and supplies electric power to a load H (for example, a device of the house) of the house. The power supply system 1 mainly includes a power storage system 10, a distribution board 20, a fuel cell 30, a first sensor 40, a second sensor 50, and an EMS 60.

The power storage system 10 stores electric power and supplies it to the load H. The power storage system 10 is provided between the system power supply K and the load H. The power storage system 10 includes a solar power generation unit 11, a storage battery 12, and a hybrid power conditioner 13.

The photovoltaic power generation unit 11 is a device that generates electricity using sunlight. The photovoltaic power generation unit 11 is composed of a solar cell panel or the like. The photovoltaic power generation unit 11 is installed in a sunny place such as on the roof of a house, for example.

The storage battery 12 is configured to be rechargeable with electric power. The storage battery 12 is composed of, for example, a lithium ion battery. The storage battery 12 is connected to the photovoltaic power generation unit 11 via a hybrid power conditioner 13 described later.

A discharge threshold is set in the storage battery 12. Here, the "discharge threshold value" is set to secure electric power in an emergency such as a power failure, and indicates the minimum amount of electricity stored that is always secured. In the present specification, the "discharge threshold value" is expressed as a ratio (for example, 30%) to the storage capacity (maximum capacity) of the storage battery 12. In the present embodiment, it is assumed that the discharge threshold value of the storage battery 12 is set to 30%. In the present embodiment, the discharge threshold value can be set in 10% increments between 0 and 50% of the storage capacity (maximum capacity) of the storage battery 12. Further, it is assumed that the storage capacity (maximum capacity) of the storage battery 12 is 5.4 [kWh].

The hybrid power conditioner 13 appropriately converts electric power (hybrid power conditioner). The hybrid power controller 13 can output the electric power generated by the solar power generation unit 11 and the electric power discharged from the storage battery 12 to the distribution line L (load H), and the electric power flowing through the distribution line L (from the system power supply K). The electric power and the electric power generated by the fuel cell 30 described later) can be output to the storage battery 12. Further, the hybrid power conditioner 13 is configured to be able to acquire information on the performance and operating state of the photovoltaic power generation unit 11 and the storage battery 12. The hybrid power conditioner 13 is connected to the middle portion (connection point P) of the distribution line L connecting the system power supply K and the load H (distribution board 20) via the electric line A1. The hybrid power conditioner 13 of the power storage system 10 can perform a load follow-up operation for adjusting the discharged (output) power based on the detection result of the first sensor 40 described later.

The distribution board 20 distributes electric power to the load H. The distribution board 20 is provided on the downstream side of the power storage system 10 (connection point P) and is connected to the load H. Although only one load H is shown in FIG. 1, the distribution board 20 is connected to a plurality of loads and distributes electric power to each load. The distribution board 20 supplies the electric power from the system power supply K, the electric power discharged from the storage battery 12, and the electric power from the fuel cell 30, which will be described later, to the load H.

The fuel cell 30 is a device that generates electricity using gas fuel such as hydrogen. The fuel cell 30 includes a power generation unit 31 and a hot water storage tank 32.

The power generation unit 31 is a power generation unit of the fuel cell 30. The power generation unit 31 is composed of a polymer electrolyte fuel cell (PEFC), a solid oxide fuel cell (SOFC), a control unit, or the like. The power generation unit 31 performs load-following operation according to the amount of electric power (total power consumption of the load H of the house) detected by the second sensor 50 described later. Further, the fuel cell 30 has a learning function of learning information on the power consumption of the load H of the house and the demand for hot water supply. In this way, the fuel cell 30 can create a power generation plan based on the information learned by the learning function. Further, the fuel cell 30 can generate power according to the power generation plan created above in response to an instruction from the EMS 60 described later.

The hot water storage tank 32 stores heat (exhaust heat) generated during power generation of the power generation unit 31 as hot water. The hot water storage tank 32 stores clean water (hot water) heated by the heat (exhaust heat) generated during power generation of the power generation unit 31.

The fuel cell 30 configured in this way stops power generation by the power generation unit 31 when the hot water storage capacity of the hot water storage tank 32 reaches the maximum capacity (when the hot water storage tank 32 becomes full and no more heat can be stored). May cause you to. Further, the fuel cell 30 starts power generation so that the amount of hot water stored in the hot water storage tank 32 reaches the maximum capacity by the time when the hot water supply demand is generated.

The first sensor 40 is provided in the middle of the distribution line L. More specifically, the first sensor 40 is provided on the upstream side (immediately upstream side of the connection point P) of the power storage system 10 (connection point P). The first sensor 40 detects the voltage (supply voltage) and the current (supply current) of the electric power (electric power flowing to the upstream side and electric power flowing to the downstream side) flowing through the location where the first sensor 40 is provided.

The second sensor 50 is provided in the middle of the distribution line L. More specifically, the second sensor 50 is provided between the power storage system 10 (connection point P) and the distribution board 20. The second sensor 50 detects the voltage (supply voltage) and the current (supply current) of the electric power (electric power flowing to the upstream side and electric power flowing to the downstream side) flowing through the location where the second sensor 50 is provided.

The EMS 60 is an energy management system that manages the operation of the power supply system 1. The EMS 60 includes an arithmetic processing unit such as a CPU, a storage unit such as a RAM or ROM, an input / output unit such as a touch panel, and the like. Various information, programs, and the like used when controlling the operation of the power supply system 1 are stored in advance in the storage unit of the EMS 60. The arithmetic processing unit of the EMS 60 can operate the power supply system 1 by executing the program and performing predetermined arithmetic processing or the like using the various information.

The EMS 60 is electrically connected to the hybrid power conditioner 13. The EMS 60 can transmit a predetermined signal to the hybrid power conditioner 13 to control the operation of the storage battery 12 (for example, charging / discharging of the storage battery 12). Further, the EMS 60 is configured so that a predetermined signal can be input from the hybrid power conditioner 13, and various information (remaining amount of electricity stored in the storage battery 12 and the like) can be acquired.

Further, the EMS 60 is electrically connected to the fuel cell 30 and can control the operation of the fuel cell 30.

In the power supply system 1 configured as described above, the storage battery 12 can be charged with the power purchased from the system power supply K and the power generated by the photovoltaic power generation unit 11 and the fuel cell 30. Further, in the power supply system 1, the power purchased from the grid power supply K, the power generated by the photovoltaic power generation unit 11 and the fuel cell 30, and the power charged in the storage battery 12 are supplied to the load H of the house. can do. Further, in the power supply system 1, the surplus (surplus power) of the power generated by the photovoltaic power generation unit 11 can be sold by flowing back to the grid power supply K.

Next, the power supply mode (mode) in the power supply system 1 will be described.

The power supply system 1 has a first mode and a second mode as power supply modes. The first mode shown below charges and discharges the storage battery 12 based on the detection results of the first sensor 40 and the second sensor 50. Further, in the second mode shown below, the storage battery 12 is charged and discharged based on the instruction from the EMS 60.

The hybrid power conditioner 13 in which the first mode is set supplies the electric power from the solar power generation unit 11 to the load H when the solar power generation unit 11 is generating electric power. Further, when the electric power from the solar power generation unit 11 is surplus with respect to the power consumption of the load H, the hybrid power conditioner 13 charges the storage battery 12 with the surplus electric power. The hybrid power controller 13 determines the surplus power when the power from the solar power generation unit 11 still remains even after charging the storage battery 12 with the maximum charging power (the maximum amount of power that the storage battery 12 can charge per unit time). Is backflowed to the system power supply S.

In supplying electric power to the load H, the hybrid power conditioner 13 performs a load following operation for determining the discharge amount of the storage battery 12 based on the detection result of the first sensor 40.

On the other hand, the hybrid power conditioner 13 in which the second mode is set charges and discharges the storage battery 12 based on the instruction from the EMS 60. The hybrid power conditioner 13 in which the second mode is set can charge the storage battery 12 with electric power (midnight electric power) from, for example, the system power supply S, based on the instruction from the EMS 60.

Here, conventionally, the fuel cell 30 may generate power (load-following operation) even during a time zone in which the power generated by the photovoltaic power generation unit 11 is surplus. However, in such a case, there is a problem that the electric power generated by the fuel cell 30 reduces the self-consumption of the electric power generated by the photovoltaic power generation unit 11. Therefore, in the power supply system 1, control (planned control) for adjusting the power generation time of the fuel cell 30 is performed.

Hereinafter, the planned control by the EMS 60 will be described with reference to FIG. The planning control shown in FIG. 2 is for planning the operation of the storage battery 12 and the fuel cell 30. In this embodiment, the next day's operation plan shall be performed. The planned control is performed before the start of the midnight power time zone (midnight time zone in which a relatively low power unit price is set in the day) (for example, 23:00 on the day).

In step S10 shown in FIG. 2, the EMS 60 predicts the next day's power demand, PV generated power, surplus power, and purchased power. In this process, the EMS 60 makes the prediction based on the data of the past generated power of the photovoltaic power generation unit 11, the weather forecast of the next day, and the like. The EMS 60 makes the prediction on the assumption that the fuel cell 30 does not generate electricity at all.

Here, the "PV generated power" indicates the power generated by the photovoltaic power generation unit 11. Further, the "surplus electric power" indicates the surplus amount of the electric power generated by the photovoltaic power generation unit 11 and the fuel cell 30 with respect to the electric power demand. Since it is assumed that the fuel cell 30 does not generate power at all, the "surplus power" predicted in step S10 is the surplus of PV power generation with respect to the power demand. The EMS 60 proceeds to step S11 after performing the process of step S10.

In step S11 shown in FIG. 2, the EMS 60 determines whether or not the surplus power> β (there is a time zone in which the surplus power is larger than β). Here, β is an arbitrary threshold value of 0 or more, and can be set to, for example, 2 kWh. By setting β to a value larger than 0, it is possible to improve (expand) the self-consumption of the electric power generated by the photovoltaic power generation unit 11 even if the prediction in step S10 deviates slightly. When the EMS 60 determines that the surplus power> β (“YES” in step S11), the EMS 60 proceeds to step S12. On the other hand, when it is determined that the surplus power does not> β (“NO” in step S11), the EMS 60 shifts to step S17.

In step S12 shown in FIG. 2, the EMS 60 gives an instruction to request power generation to the fuel cell 30 in a time zone other than the surplus generation time and a time zone other than the time zone in which the purchased power is less than γ. Here, the "surplus generation time" indicates a time zone in which surplus power is generated (a time zone in which surplus power> β is predicted in step S11). Further, γ is an arbitrary threshold value of 0 or more, and is set in consideration of the power generation efficiency of the fuel cell 30. γ can be, for example, 0.15 kW. By setting γ to a value larger than 0, it is possible to maintain the power generation efficiency of the fuel cell even if the prediction in step S10 deviates slightly.

Further, the "power generation request instruction" indicates the power generation time from the EMS 60 to the fuel cell 30. The fuel cell 30 that has received the power generation request instruction will generate power when a predetermined condition is satisfied in the instructed power generation time. That is, the fuel cell 30 does not always generate power even if it receives a power generation request instruction. For example, if the amount of hot water stored in the hot water storage tank 32 reaches the maximum capacity (if the hot water storage tank 32 is full), the fuel cell 30 generates power. Not performed.

As described above, in step S12, the EMS 60 issues a power generation request instruction to the fuel cell 30 in a time zone other than the surplus generation time (a time zone other than the time zone in which surplus power> β is predicted in step S11). By doing so, the power generation of the fuel cell 30 is indirectly stopped at the surplus generation time. Further, the EMS 60 indirectly stops the power generation of the fuel cell 30 in the time zone when the purchased power is less than γ by instructing the fuel cell 30 to generate power in a time zone other than the time zone when the purchased power is less than γ. Will be made to. The EMS 60 proceeds to step S13 after performing the process of step S12.

In step S13 shown in FIG. 2, the EMS 60 updates the prediction of surplus power. In this process, the EMS 60 updates the prediction of the surplus power among the predictions of the power demand, the PV power generation power, the surplus power, and the purchased power obtained in step S11 in consideration of the power generation of the fuel cell 30. Specifically, the EMS 60 is based on the assumption that the fuel cell 30 generates power during the power generation time specified in step S12 (a time zone other than the surplus generation time and a time zone other than the time zone when the purchased power is less than γ). Update. The EMS 60 proceeds to step S14 after performing the process of step S13.

In step S14 shown in FIG. 2, the EMS 60 determines whether or not the total surplus electric energy> the storable amount (the total surplus electric energy is larger than the storable amount). Here, the "total surplus electric energy" indicates the total of the surplus electric power of the next day updated in step S13 (the total of the surplus electric power from 9:00 to 17:00). The "chargeable amount" indicates the maximum value that the storage battery 12 can store in consideration of the discharge threshold value, and is calculated by "storage capacity × (1-discharge threshold value)". For example, when the discharge threshold value is 30%, the chargeable amount is calculated by "storage capacity × (1-0.3)". When the EMS 60 determines that the total surplus electric energy> the amount that can be stored (“YES” in step S14), the process proceeds to step S15. On the other hand, when it is determined that the total surplus electric energy does not equal the amount that can be stored (“NO” in step S14), the process proceeds to step S16.

In addition, in the case of "YES" in step S14, even if the storage battery 12 is fully charged (even if it is charged to the maximum capacity) according to the total surplus electric power of the next day, the electric power generated by the solar power generation unit 11 is still surplus. Indicates to do. On the other hand, in the case of "NO" in step S14, when the storage battery 12 cannot be fully charged with the total surplus electric power of the next day, or when the storage battery 12 is fully charged with the total surplus power of the next day, the photovoltaic power generation unit It shows that the electric power generated in 11 is not surplus.

In step S15 shown in FIG. 2, the EMS 60 sets the target remaining charge as the total power consumption in the early morning time zone (from the charging end time to the surplus generation time (the start time of the surplus generation time zone)). Here, the "target remaining amount of electricity stored" indicates the target (reserved) amount of electricity stored that can be discharged at the end time of charging. Further, the "charging end time" is a time when charging of midnight electric power having a low unit price of electric power is completed, that is, an end time of a midnight electric power time zone. The EMS 60 ends the planning control flow shown in FIG. 2 after performing the process of step S15.

On the other hand, in step S16 shown in FIG. 2, the EMS 60 sets the target remaining storage amount as the chargeable amount (= storage capacity × (1-discharge threshold value)).

In this way, when it is predicted that the power generated by the photovoltaic power generation unit 11 will still be surplus even if the storage battery 12 is fully charged due to the total surplus power amount on the next day (“YES” in step S14), in the early morning hours. Only the required amount of power is purchased (purchased) from the grid power source S (step S15). On the other hand, it is predicted that the storage battery 12 cannot be fully charged with the total surplus electric energy of the next day, or if the storage battery 12 is fully charged with the total surplus electric energy of the next day, the electric power generated by the photovoltaic power generation unit 11 will not be surplus. If this is the case (“NO” in step S14), the amount of power that can fully charge the storage battery 12 is purchased from the grid power source S (step S16). The EMS 60 ends the planning control flow shown in FIG. 2 after performing the process of step S16.

On the other hand, in step S17 shown in FIG. 2, the EMS 60 issues a power generation request instruction to the fuel cell 30 in a time zone other than the midnight power time zone and a time zone other than the time zone in which the purchased power is less than γ.

As described above, in step S17, the EMS 60 indirectly stops the power generation of the fuel cell 30 in the midnight power time zone by instructing the fuel cell 30 to generate power in a time zone other than the midnight power time zone. It will be. Further, the EMS 60 indirectly stops the power generation of the fuel cell 30 in the time zone when the purchased power is less than γ by instructing the fuel cell 30 to generate power in a time zone other than the time zone when the purchased power is less than γ. Will be made to. The EMS 60 proceeds to step S18 after performing the process of step S17.

In step S18 shown in FIG. 2, the EMS 60 updates the prediction of surplus power. In this process, the EMS 60 updates the prediction of the surplus power among the predictions of the power demand, the PV power generation power, the surplus power, and the purchased power obtained in step S11 in consideration of the power generation of the fuel cell 30. Specifically, the EMS 60 is updated on the assumption that the fuel cell 30 generates power during the power generation time requested in step S17 (a time zone other than the midnight charging time and a time zone other than the time zone when the purchased power is less than γ). conduct. The EMS 60 ends the planning control flow shown in FIG. 2 after performing the process of step S18.

In this way, the EMS 60 determines the power generation time of the fuel cell 30 and the target remaining charge of the storage battery 12.

Next, the execution control by the EMS 60 will be described with reference to FIG. The flow shown in FIG. 3 is always executed after the flow shown in FIG. 2 is executed.

In step S20 shown in FIG. 3, the EMS 60 determines whether or not the current time t is the charging time. Here, the "charging time" indicates the time during which the storage battery 12 can be charged (for example, from 23:00 to 7:00), and is preset by the resident of the house. When the EMS 60 determines that the current time t is the charging time (“YES” in step S20), the EMS 60 proceeds to step S21. On the other hand, when the EMS 60 determines that the current time t is not the charging time (“NO” in step S20), the EMS 60 shifts to step S24.

In step S21 shown in FIG. 3, the EMS 60 determines whether or not "current remaining charge- (storage capacity x discharge threshold value) ≥ target remaining charge". Here, the "target remaining charge" is determined in the planned control flow shown in FIG. When the EMS 60 determines that "current storage capacity- (storage capacity x discharge threshold value) ≥ target storage capacity" ("YES" in step S21), the process proceeds to step S22. On the other hand, when the EMS 60 determines that "current remaining charge- (storage capacity x discharge threshold value) ≥ target remaining charge" ("NO" in step S21), the process proceeds to step S23.

In the case of "YES" in step S21, it means that the amount of power that can be discharged (hereinafter referred to as "remaining amount of discharge") among the electric power stored in the storage battery 12 is equal to or less than the target remaining amount of stored power. Shown. On the other hand, the case of "NO" in step S21 indicates that the amount of electric power that can be discharged out of the electric power stored in the storage battery 12 is larger than the target remaining amount of electric power.

In step S22 shown in FIG. 3, the EMS 60 sets the mode of the storage battery 12 to the second mode. As a result, the storage battery 12 charges the electric power (midnight electric power) from the system power supply S so that the remaining amount of charge that can be discharged becomes the target remaining amount of electricity stored. The EMS 60 ends the execution control flow shown in FIG. 3 after performing the process of step S22.

In this way, in step S22, if “total surplus power amount> chargeable amount” (when it is expected that the storage battery 12 cannot be fully charged due to surplus power on the next day, “NO” in step S14), the target power storage Since the remaining amount is the amount that can be stored (step S16), the storage battery 12 is charged until the electric power (midnight electric power) from the system power source S is fully charged. On the other hand, when "total surplus electric energy> chargeable amount" (when it is expected that the storage battery 12 can be fully charged by the surplus electric power of the next day, "YES" in step S14), the target remaining electric energy is in the early morning hours. Since it is the total power consumption (step S15), the power from the grid power supply S (midnight power) is not charged until the storage battery 12 is fully charged, and only the total power consumption in the early morning hours is charged. Will be done.

On the other hand, in step S23 shown in FIG. 3, the EMS 60 sets the mode of the storage battery 12 to the standby mode. As a result, the storage battery 12 does not charge or discharge. The EMS 60 ends the execution control flow shown in FIG. 3 after performing the process of step S22.

In this way, the target remaining chargeable amount of the storage battery 12 (the amount of electric power that can be discharged out of the electric power stored in the storage battery 12) is always secured in the midnight power time.

On the other hand, in step S24 shown in FIG. 3, the EMS 60 sets the mode of the storage battery 12 to the first mode. As a result, the storage battery 12 charges the surplus power if there is surplus power, and discharges the surplus power if the power is insufficient with respect to the power demand. The EMS 60 proceeds to step S25 after performing the process of step S24.

In step S25 shown in FIG. 3, the EMS 60 determines whether or not the current time t is in the early morning time zone (from the charging end time to the surplus generation time (the start time of the surplus generation time zone)). When the EMS 60 determines that the current time t is in the early morning time zone (“YES” in step S25), the EMS 60 proceeds to step S26. On the other hand, when the EMS 60 determines that the current time t is not in the early morning time zone (“NO” in step S25), the EMS 60 shifts to step S28.

In step S26 shown in FIG. 3, the EMS 60 determines whether or not “total surplus electric energy> chargeable amount + (storage capacity × 10%)”. When the EMS 60 determines that "total surplus electric energy> chargeable amount + (storage capacity x 10%)" ("YES" in step S26), the process proceeds to step S27. On the other hand, when the EMS 60 determines that “total surplus electric energy> storage capacity + (storage capacity × 10%)” (“NO” in step S26), the execution control flow shown in FIG. 3 is terminated.

The case of "YES" in step S26 indicates that there is sufficient surplus power to fully charge the storage battery 12 even if the discharge threshold value is lowered by one step. On the other hand, the case of "NO" in step S26 indicates that the storage battery 12 cannot be fully charged with the surplus power when the discharge threshold value is lowered by one step.

In step S27 shown in FIG. 3, the EMS 60 performs a process of lowering the discharge threshold value by one step. In this process, the EMS 60 changes (lowers) the discharge threshold to 20%, for example, when the current discharge threshold is 30%. The EMS 60 ends the execution control flow shown in FIG. 3 after performing the process of step S27.

In this way, the charge / discharge amount of the storage battery 12 can be increased by lowering the discharge threshold when the surplus power can be charged. Therefore, the power consumption in the early morning time of the load H is calculated by the power from the storage battery 12. It can be easily covered, and the amount of power purchased from the grid power source S can be reduced.

On the other hand, in step S28 shown in FIG. 3, the EMS 60 determines whether or not “discharge threshold value <set value (30%)”. The "set value" referred to here is a discharge threshold value set in advance (before the execution control shown in FIG. 3) by the resident of the house, and is set to 30% in the present embodiment. When the EMS 60 determines that “discharge threshold value <set value (30%)” (“YES” in step S28), the process proceeds to step S29. On the other hand, when it is determined that the EMS 60 is not “discharge threshold <set value (30%)” (“NO” in step S28), the execution control flow shown in FIG. 3 is terminated.

In step S29 shown in FIG. 3, the EMS 60 performs a process of returning the discharge threshold value to the set value (30%). As a result, sufficient electric power can be secured in the storage battery 12 in case of an emergency. The EMS 60 ends the execution control flow shown in FIG. 3 after performing the process of step S29.

Hereinafter, a specific example of setting the power generation time of the fuel cell 30 will be shown with reference to FIGS. 4 and 5.

FIG. 4 is a diagram showing (prediction) the power consumption, PV power generation power, and the like before adjusting the power generation time of the fuel cell 30. In the example shown in FIG. 4, the fuel cell 30 is constantly performing load-following operation, and is generating power (load-following operation) even during a time zone (around 7:00 to 18:00) when surplus electric power is generated. Therefore, during the time period when surplus power is generated (around 7:00 to 18:00), the power generated by the photovoltaic power generation unit 11 is charged to the storage battery 12 without being used for power demand, and the surplus power is still in the grid. Power is sold to the power supply K.

FIG. 5 is a diagram showing the power demand (power consumption), PV power generation power, and the like (prediction) after adjusting the power generation time of the fuel cell 30. In the example shown in FIG. 5, since the fuel cell 30 has stopped power generation (not giving a power generation request instruction) during the time zone when surplus power is generated (around 8:00 to 18:00 on the second day), sunlight is used. A part of the electric power generated by the power generation unit 11 is used for electric power demand (self-consumed). In the example shown in FIG. 5, the storage battery 12 is charged with the midnight power by the total power consumption in the early morning time during the midnight power time zone (around 1 to 3 o'clock) on the second day.

As described above, the power supply system 1 according to the present embodiment sets the power generation time of the fuel cell 30 to a time zone in which surplus power is not generated by executing the planned control flow shown in FIG. 2 (shown in FIG. 2). Step S12). That is, the power generation of the fuel cell 30 is stopped in the time zone in which the surplus power is generated (surplus generation time zone). By doing so, the self-consumption rate of the generated power of the photovoltaic power generation unit 11 can be improved by the amount of the reduced power generated by the fuel cell 30. As a result, when the unit price of electricity generated by the photovoltaic power generation unit 11 is lower than the unit price of electricity purchased at midnight, the utility cost can be reduced.

Further, in the power supply system 1 according to the present embodiment, the power generation time of the fuel cell 30 is set to a time zone in which the purchased power is relatively large (step S12 shown in FIG. 2). That is, the power generation of the fuel cell 30 is stopped during the time when the purchased power is relatively low. Here, in the fuel cell 30, in general, when the partial load operation (operation with reduced output) is performed, the power generation efficiency (and thus the total efficiency) is lower than when the rated operation is performed. In the power supply system 1 according to the present embodiment, even in the time zone when surplus power is not generated, the power generation of the fuel cell 30 is stopped in the time zone when the purchased power is relatively small, so that the output is relatively small. It is possible to prevent the operation of the fuel cell 30 and to maintain (improve) the power generation efficiency (and thus the total efficiency) of the fuel cell 30.

Further, in the power supply system 1 according to the present embodiment, when a relatively large amount of surplus power can be expected on the next day (“YES” in step S14), the power from the grid power source S (midnight power) in the midnight power time zone. Is not charged until the storage battery 12 is fully charged, but the late-night power is charged to the storage battery 12 only for the power demand in the early morning time zone (step S15). As a result, it is possible to reduce the amount of electricity purchased at midnight and increase the amount of charge of the surplus electricity to the storage battery 12. By doing so, the self-consumption rate of the generated power of the photovoltaic power generation unit 11 can be improved. Further, when the unit price of electricity generated by the photovoltaic power generation unit 11 is lower than the unit price of electricity purchased at midnight, the utility cost can be reduced.

On the other hand, when a relatively large amount of surplus power cannot be expected on the next day (“NO” in step S14), the storage battery 12 is charged with power (midnight power) from the system power supply S so as to be fully charged during the midnight power time zone. (Step S16). As a result, the electric power charged in the storage battery 12 in the daytime can be used, and the utility cost can be reduced as compared with charging the electric power from the system power supply S in the daytime.

Further, in the power supply system 1 according to the present embodiment, when the surplus power sufficient to fully charge the storage battery 12 can be expected even if the discharge threshold value of the storage battery 12 is lowered by one step (“YES” in step S26), the storage battery 12 The discharge threshold is lowered by one step. As a result, the charge / discharge amount of the storage battery 12 can be expanded, so that the power consumption in the early morning time of the load H can be easily covered by the power from the storage battery 12, and the amount of power purchased from the system power supply S can be increased. Can be reduced. Further, even when the power consumption of the load H suddenly increases, the charging power of the storage battery 12 can be used.

As described above, the power supply system 1 according to the present embodiment has a solar power generation unit 11 (power generation unit) capable of generating power using natural energy, and heat generated during power generation as well as being able to generate power using fuel. The EMS 60 includes a fuel cell 30 for storing the fuel cell 30 and an EMS 60 (control unit) for controlling the operation of the fuel cell 30, and the EMS 60 is a surplus of the electric power generated by the solar power generation unit 11 with respect to the electric power demand. When the surplus power to be generated is predicted and it is predicted that there is a time zone in which the surplus power is larger than the predetermined value (β) (YES in step S11 shown in FIG. 2), the surplus power is relative to the fuel cell 30. Is instructed to generate power in a time zone other than the time zone in which the above occurs (step S12 shown in FIG. 2).

With such a configuration, it is possible to improve the self-consumption of the electric power generated by the photovoltaic power generation unit 11.
Specifically, the power generation time of the fuel cell 30 is set in a time zone in which the surplus power is not generated (that is, the power generation of the fuel cell 30 is stopped in the time zone in which the surplus power is generated (surplus generation time zone)). As a result, the self-consumption rate of the generated power of the solar power generation unit 11 can be improved by the amount of the reduced power generated by the fuel cell 30.
Further, the fuel cell 30 may not be able to generate electricity when the hot water storage tank 32 is full. Therefore, if the fuel cell 30 is generated during the time zone in which the surplus power is generated (surplus generation time zone), the hot water storage tank 32 fills up early, and the fuel cell 30 is used in the time zone when the surplus power is not generated. Even if you try to generate electricity, you may not be able to generate electricity. In the power supply system 1 according to the present embodiment, the hot water storage tank 32 is filled up at an early stage by stopping the power generation of the fuel cell 30 in the time zone in which the surplus power is generated (surplus generation time zone). It can be suppressed, and by extension, it is possible to suppress the fuel cell 30 from being unable to generate electricity during the time period when surplus electric power is not generated.

Further, in the EMS 60, when it is predicted that there is a time zone in which the surplus power is larger than the predetermined value (β) (YES in step S11 shown in FIG. 2), the amount of power purchased from the grid power supply K is a predetermined value. It is instructed to generate power in a time zone other than the time zone less than (γ) (step S12 shown in FIG. 2).

With such a configuration, it is possible to maintain the power generation efficiency of the fuel cell 30.
Specifically, since the operation of the fuel cell 30 with a relatively small output is suppressed, the power generation efficiency of the fuel cell 30 can be maintained (improved).

Further, when it is predicted that there is no time zone in which the surplus power is greater than the predetermined value (β) (NO in step S11 shown in FIG. 2), the EMS 60 has a midnight power time zone with respect to the fuel cell 30. It is instructed to generate power in a time zone other than the above (step S17 shown in FIG. 2).

With this configuration, when the midnight power is lower than the power generation cost of the fuel cell 30, the utility cost can be reduced.
Specifically, by stopping the power generation of the fuel cell 30 during the midnight power time zone, the midnight power is used for the power demand. Therefore, if the midnight power is lower than the power generation cost of the fuel cell 30, the utility cost will be charged. It can be reduced.

Further, the power supply system 1 according to the present embodiment includes a storage battery 12 capable of charging and discharging electric power, and the EMS 60 is predicted to have a larger surplus electric power than the storage capacity of the storage battery 12 (FIG. FIG. YES) in step S14 shown in 2, the storage battery is charged with midnight power by the amount of power demand until the time when power generation is started by the power generation unit (step S15 shown in FIG. 2).

With this configuration, the amount of surplus power charged to the storage battery 12 while being covered by midnight power (total power consumption in the early morning hours) until the time when power generation is started by the photovoltaic power generation unit 11. Can be expanded.
Specifically, since the storage battery 12 is charged with the late-night power only for the total power consumption in the early morning time zone, it is possible to increase the charge amount of the surplus power to the storage battery 12.

Further, the power supply system 1 according to the present embodiment includes a storage battery 12 capable of charging and discharging electric power, and the EMS 60 is predicted to have a smaller surplus electric power than the storage capacity of the storage battery 12 (FIG. FIG. NO) in step S14 shown in 2, the storage battery is fully charged with midnight power (step S16 shown in FIG. 2).

With such a configuration, it is possible to reduce utility costs.
Specifically, since the midnight power charged in the storage battery 12 can be used in the daytime, the utility cost can be reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above configuration, and various modifications can be made within the scope of the invention described in the claims.

For example, in the present embodiment, the power supply system 1 is provided in a house, but the present invention is not limited to this, and may be provided in an office or the like, for example.

Further, in the present embodiment, the power generation unit is a photovoltaic power generation unit 11 that generates power by using sunlight, but it generates power by using other natural energy (for example, hydraulic power or wind power). You may.

Further, in the present embodiment, in step S12 shown in FIG. 2, the EMS 60 gives an instruction to request power generation to the fuel cell 30 in a time zone other than the surplus generation time and a time zone other than the time zone in which the purchased power is less than γ. However, the power generation request instruction may be given only during the time other than the surplus generation time.

Further, in the present embodiment, in step S14 shown in FIG. 2, it is determined whether or not the total surplus electric energy> the rechargeable amount (the total surplus electric energy is larger than the rechargeable amount), but the total surplus It may be determined whether or not the electric energy ≥ the electric energy that can be stored (the total surplus electric energy is equal to or greater than the electric energy that can be stored).

1 Power supply system 11 Photovoltaic power generation unit 12 Storage battery 30 Fuel cell 60 EMS

Claims (5)

A power generation unit that can generate electricity using natural energy,
A fuel cell that can generate electricity using fuel and stores the heat generated during power generation,
A control unit that controls the operation of the fuel cell,
Equipped with
The control unit
Of the electric power generated by the power generation unit, the surplus electric power that is surplus with respect to the electric power demand is predicted, and the surplus electric power is predicted.
When it is predicted that there is a time zone in which the surplus power is greater than a predetermined value, the fuel cell is instructed to generate power in a time zone other than the time zone in which the surplus power is generated.
Power supply system. The control unit
If it is predicted that there will be a time zone in which the surplus power is greater than the predetermined value, an instruction is given to generate power in a time zone other than the time zone in which the amount of power purchased from the grid power source is less than the predetermined value.
The power supply system according to claim 1. The control unit
When it is predicted that there is no time zone in which the surplus power exceeds a predetermined value, the fuel cell is instructed to generate power in a time zone other than the midnight power time zone.
The power supply system according to claim 1 or 2. Equipped with a storage battery that can charge and discharge electric power
The control unit
When the surplus power is predicted to be larger than the storage capacity of the storage battery, the storage battery is charged with midnight power by the amount of power demand until the time when power generation is started by the power generation unit.
The power supply system according to any one of claims 1 to 3. Equipped with a storage battery that can charge and discharge electric power
The control unit
When the surplus power is predicted to be less than the storage capacity of the storage battery, the storage battery is fully charged with midnight power.
The power supply system according to any one of claims 1 to 4.

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