JP2016093081A - Power supply system and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively suppress power generation of a fuel cell unit without requiring operation stop of the fuel cell unit.SOLUTION: A power supply system 100 comprises: a fuel cell unit 11 connected to a main line LM; a current detection unit 15 for detecting current flowing in the main line LM; and a control unit 12 for controlling operation of the fuel cell unit 11 on the basis of flow power corresponding to the current detected by the current detection unit 15. The control unit 12 makes the fuel cell unit 11 generate power so that the fuel cell unit 11's power generation output follows demand power, when the flow power is higher than minimum purchasing power; and lowers the fuel cell unit 11's power generation output when the flow power is equal to or lower than the minimum purchasing power before making the fuel cell unit 11 be in a standby state when the power generation output has become equal to or lower than predetermined output. The control unit 12 comprises a threshold changeover unit 13 for changing over the minimum purchasing power at least between a normal value α and an increase value β1 larger than the normal value α.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply system and a control device.

  As a conventional power supply system, the one described in Patent Document 1 is known. The power supply system described in Patent Document 1 includes a power supply source such as a system power supply, and a fuel cell unit that generates power, and in addition to supplying power from the power supply source to a load, fuel It is intended to supply electric power to the load also from the battery unit.

JP2011-217527A

  Generally, in the power supply system as described above, the operation of the fuel cell unit is controlled by the control unit, and the load cell following operation (that is, the power generation output of the fuel cell unit follows the demand power on the load side). Operation to generate electricity). In this case, however, the fuel cell unit is preferentially load-followed under certain conditions, such as using the power of the system power supply to reduce the operating cost of the entire power supply system. There is a possibility that. Therefore, it is desired to selectively suppress the power generation of the fuel cell unit in order to preferentially use the power of the power supply unit under such specific conditions.

  Here, unlike the other power supply means, the fuel cell unit often requires a great deal of time for start-up (power-on) and operation stop (power-off). Therefore, simply stopping the operation of the fuel cell unit to suppress power generation is not practical because of its characteristics.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a power supply system and a control device that can selectively suppress power generation of the fuel cell unit without requiring operation stop of the fuel cell unit. And

  The power supply system according to the present invention is provided on the power supply source side of the fuel cell unit connected to the main line connected to the load from the power supply source and on the main line with respect to the fuel cell unit connected to the main line, and detects a current flowing through the main line And a control unit that controls the operation of the fuel cell unit based on the power flow corresponding to the current detected by the current detection unit. When it is larger than the discharge threshold, the fuel cell unit generates power so that the power generation output of the fuel cell unit follows the demand power on the load side of the connection unit. When the power generation output is reduced and the power generation output falls below a predetermined output, the fuel cell unit is placed in a standby state, and the discharge threshold is switched between at least a first value and a second value greater than the first value. Threshold switching unit Provided La.

  A control device according to the present invention is provided on a power supply source side of a fuel cell unit connected to a main line connected to a load from a power supply source and connected to the fuel cell unit on the main line, and detects a current flowing through the main line A control unit mounted on a power supply system including a control unit that controls operation of the fuel cell unit based on power flow corresponding to the current detected by the current detection unit. When the tidal power is larger than the discharge threshold, the control unit causes the fuel cell unit to generate power so that the power generation output of the fuel cell unit follows the demand power on the load side of the connection unit. In this case, when the power generation output by the fuel cell unit is reduced and the power generation output falls below a predetermined output, the fuel cell unit is placed in a standby state, and at least a first value and a second value greater than the first value. Discharge threshold between Ri, further comprising a threshold switch unit for changing.

  In such a power supply system and control device according to the present invention, when the discharge threshold is the first value, the load following operation is performed in the fuel cell unit when the demand power exceeding the first value is generated on the load side. On the other hand, by switching the discharge threshold value to a second value larger than the first value, the fuel cell unit performs load following operation as long as the demand power does not exceed the second value even if the demand power exceeds the first value. Without changing to a standby state (idling state in which no electric power is output from the fuel cell unit). Therefore, according to the present invention, it is possible to selectively suppress power generation in the fuel cell unit without requiring the fuel cell unit to be shut down.

  In the power supply system according to the present invention, the threshold switching unit may switch the discharge threshold according to the time zone. In this case, it is possible to configure the power supply system so that the discharge threshold becomes the second value in an arbitrary time zone, and to suppress power generation in the fuel cell unit in that time zone.

  In the power supply system according to the present invention, the power supply source includes a system power supply, and the threshold switching unit switches so that the discharge threshold is set to the second value in at least a part of the night time zone. Also good. In the nighttime period, demand power is often small, and if the fuel cell unit performs load following operation for such small demand power, the operating efficiency of the fuel cell unit may deteriorate and the economic efficiency may be impaired. There is sex. Therefore, by setting the discharge threshold to the second value in at least a part of the night time zone, the power generation of the fuel cell unit is suppressed during the time zone, and the operation of the fuel cell unit with poor operating efficiency is suppressed. It is possible to obtain economic merit.

  In the power supply system according to the present invention, the power supply source includes a photovoltaic power generation system, and the threshold value switching unit sets the discharge threshold value to the second value in at least a part of the daytime time zone. You may switch. In the daytime hours, power can be supplied by solar power generation. However, there is a case where the operation cost of the entire power supply system can be reduced by using power by solar power generation with priority. Therefore, by setting the discharge threshold to the second value in at least a part of the daytime period, the power generation of the fuel cell unit is suppressed and the power of the solar power generation is preferentially used in the period. And economic benefits can be obtained.

  The power supply system according to the present invention includes a first power storage unit that is connected to the power supply source side of the main line from the current detection unit and is capable of charging and discharging power, and the threshold value switching unit is the amount of power stored in the first power storage unit. May be switched so that the discharge threshold is set to the second value when the amount is larger than a certain remaining amount. In order to effectively use the first power storage unit, it is desirable to use the stored power until the amount of power stored in the first power storage unit becomes equal to or less than a certain remaining amount. Therefore, when the amount of power stored in the first power storage unit is greater than a certain remaining amount, the discharge threshold is set to the second value, thereby suppressing power generation in the fuel cell unit and preferentially storing the power stored in the first power storage unit. Be available.

  The power supply system according to the present invention includes a second power storage unit connected to the load side of the main line and connected to the fuel cell unit and capable of charging and discharging electric power, and the second value is the value of the second power storage unit. It may be larger than the charging power. If the discharge threshold is less than or equal to the charging power of the second power storage unit (power required for charging), for example, even when the power of the power supply source is used, the operating cost of the entire power supply system can be reduced. The fuel cell unit always performs load following operation when the second power storage unit is charged. Therefore, if the second value is set to be larger than the charging power of the second power storage unit, when the discharge threshold is switched to the second value, the fuel is required as long as the demand power does not exceed the second value even when the second power storage unit is charged. The battery unit can be shifted to the standby state.

  According to the present invention, it is possible to selectively suppress power generation in the fuel cell unit without requiring operation stop of the fuel cell unit.

1 is a schematic configuration diagram illustrating a power supply system according to a first embodiment. It is a schematic block diagram which shows the power supply system which concerns on 2nd Embodiment. It is a figure which shows the example of the control map referred when switching the minimum electric power purchase in a threshold value switching part. It is a schematic block diagram which shows the power supply system which concerns on 3rd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

[First Embodiment]
A first embodiment of the present invention will be described. FIG. 1 is a schematic configuration diagram illustrating a power supply system 100 according to the first embodiment. As shown in FIG. 1, the power supply system 100 is a system for supplying electric power to a load E (residential household load or the like) in, for example, a general household. The power supply system 100 includes a main line LM connected to the load E from the power supply source 2, a fuel cell system 10 connected to the main line LM via the connection unit 3, and the power supply source 2 side of the main line LM from the connection unit 3. And a provided current detection unit 15.

  The power supply source 2 includes a system power supply 2a and a solar power generation system 2b. The system power supply 2a is a power supply supplied from, for example, a distribution network owned by an electric power company. The solar power generation system 2b is a power source that generates power using sunlight, and is configured to be linked to the system power source 2a. The power supply source 2 may include another distributed power source such as a wind power generation system linked to the system power source 2a.

  The trunk line LM is a wiring that supplies power from the power supply source 2 to the load E. As the main line LM, a single-phase three-wire type used as a general household lead-in line can be adopted. The electrical system for power distribution in the main line LM is not particularly limited, and may be a single-phase two-wire system, a three-phase three-wire system, or a three-phase four-wire system.

  The fuel cell system 10 outputs electric power using hydrocarbon fuel such as LP gas, city gas, and kerosene, and includes a fuel cell unit 11 and a control unit 12. The fuel cell unit 11 generates electric power, a reformer that generates a reformed gas containing hydrogen by reforming a hydrocarbon fuel, and a fuel cell that generates electric power using the reformed gas A cell or the like is provided. The fuel cell unit 11 outputs (discharges) the generated power to the load E side via the connection unit 3 and the main line LM. The rated power output of the fuel cell system 10 is about 700 W, for example.

  The control unit 12 is configured by, for example, a device that performs electronic control (for example, a device including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface). Yes. The control unit 12 controls the operation of the fuel cell unit 11 based on the power flow corresponding to the current detected by the current detection unit 15 (details will be described later).

  The current detection unit 15 is configured by, for example, a current transformer (CT). The current detection unit 15 detects a current flowing through the main line LM. Specifically, the current detection unit 15 has an annular core, and can detect a current flowing through the trunk line LM connected to pass through the inside of the core. The current detection unit 15 is electrically connected to the control unit 12 and transmits the current value of the detected current to the control unit 12.

  Next, the control unit 12 will be specifically described. The controller 12 controls the operation of the fuel cell system 10 so that the power output from the fuel cell system 10 does not flow backward. Specifically, the control unit 12 calculates the tidal current power from the current value detected by the current detection unit 15, the voltage value detected by a voltage detection unit (not shown) included therein, and the phase thereof. When the tidal power is larger than the discharge threshold, the control unit 12 causes the fuel cell unit 11 to generate power so as to perform load following operation. On the other hand, when the tidal power is less than or equal to the discharge threshold, the power generation of the fuel cell unit 11 is suppressed until the tidal power exceeds the discharge threshold, and the power generation output by the fuel cell unit 11 is reduced. When the power generation output becomes equal to or less than the predetermined output, the fuel cell unit 11 is set in a standby state.

  The tidal current power is power at the position where the current detection unit 15 is disposed on the main line LM, and is based on the current detected by the current detection unit 15 and the voltage detected by the voltage detection unit (that is, the power supply source). Power in the direction from the second side toward the load E). The discharge threshold here is set as the minimum electric power purchased. The load following operation is an operation in which the fuel cell unit 11 generates power so that the power generation output of the fuel cell unit 11 follows the demand power on the load E side with respect to the connection unit 3. The term “predetermined output or less” means a value that is equal to or less than a preset output value, and is not particularly limited. The standby state is an idling state in which power is not output from the fuel cell unit 11. The standby state does not include a state in which the fuel cell unit 11 is stopped (power is turned off).

  In the configuration shown in FIG. 1, the power demand (power consumption) on the load E side is the sum of the power generation output of the fuel cell unit 11 and the power supplied from the power supply source 2. When the power generation output from the power supply source 2 is larger than the minimum power purchase power, the control unit 12 increases or decreases the power generation output of the fuel cell unit 11 so that the total becomes demand power. On the other hand, the control unit 12 reduces the power generation output by the fuel cell unit 11 when the power supplied from the power supply source 2 is less than or equal to the minimum purchased power, and the fuel cell unit 11 when the power generation output falls below a predetermined output. Is set to a standby state to suppress discharge of the fuel cell unit 11.

  Here, the control unit 12 of the present embodiment includes a threshold switching unit 13 that switches the minimum power purchase, which is a discharge threshold, between a normal value (first value) α and an increase value (second value) β1. ing. In other words, the control unit 12 is provided with a function capable of changing the set value of the minimum power purchase from the normal value α to the increase value β1 or from the increase value β1 to the normal value α.

  The normal value α is set, for example, from the viewpoint of preventing reverse power flow and is about several tens of watts. The increase value β1 has a value significantly larger than the normal value α and is set to 5000W. The increase value β1 can be set based on, for example, the amperage of the contract power breaker. When the increase value β1 is set to a value larger than the contract power, the demand power is always less than or equal to the minimum purchased power, and as a result, the fuel cell unit 11 can always shift to the standby state.

  The threshold switching unit 13 may switch the minimum power purchase power manually by a user via an operation unit such as a touch panel, or may automatically switch the minimum power purchase power under a specific condition. The threshold switching unit 13 may switch the minimum power purchase between the normal value α and the increase value β1 according to the time zone. In this case, the threshold value switching unit 13 may include a control map related to the minimum power purchase power associated with a plurality of time zones in advance, and may switch the minimum power purchase power based on the control map. Alternatively, the threshold switching unit 13 may include a timer unit, for example, and may switch the minimum power purchase power according to a time zone set by the user via the timer unit.

  For example, the threshold switching unit 13 switches the minimum power purchase power to an increase value β1 of 5000 W in an arbitrary time zone. Thereby, if there is no demand power of 5000 W or more in this arbitrary time zone, the fuel cell unit 11 does not start power generation. Therefore, in a consumer whose normal demand power is less than 5000 W, power is supplied only from the power supply source 2 without being supplied with power from the fuel cell unit 11 in the arbitrary time zone.

  When switching the lowest power purchase power in an arbitrary time zone, the threshold switching unit 13 may be configured as follows. That is, the threshold switching unit 13 may perform switching so that the minimum power purchase is set to the increase value β1 in at least a part of the night time zone. The night time zone is the time zone from sunset to sunrise. The night time zone includes a midnight time zone when the power purchase fee of the power supplied from the system power supply 2a is cheap. Alternatively, the threshold switching unit 13 may perform switching so that the minimum purchased power is set to the increase value β1 in at least a part of the daytime time zone. Daytime is the time zone from sunrise to sunset. As the “time”, standard time may be used, or a specific time set in the fuel cell system 10 or the like may be used (hereinafter the same).

Moreover, the threshold value switching part 13 may be comprised so that minimum electric power purchase can be switched so that it may become increase value (beta) 1, when it corresponds to either of the following conditions, for example, in order to improve economic merit.
Condition 1: Fuel cost required for power generation of the fuel cell system 10> Purchase price of the system power supply 2a Condition 2: Time zone in which the demand power is smaller than a predetermined value
(Predetermined value: The operating efficiency of the fuel cell system 10 deteriorates and the required fuel amount increases.
Value defined based on whether or not)
Condition 3: Electricity sales fee of the solar power generation system 2b <
Fuel cost required for power generation of the fuel cell system 10

  Note that switching of the minimum power purchase by the threshold switching unit 13 is not limited, and instead of or in addition to the above, the minimum power purchase may be switched according to, for example, the season, region, surrounding weather, and the like. . The threshold switching unit 13 determines whether there is a certain amount of surplus in the amount of hot water stored by the fuel cell system 10, and switches the minimum power purchase power so that the increase value β1 is obtained when there is a surplus in the amount of hot water stored. Also good. The threshold switching unit 13 may switch the lowest power purchase power between three or more different values. The control unit 12 and the threshold value switching unit 13 constitute the control device 1 mounted on the power supply system 100.

  As described above, in the present embodiment, when the minimum purchased power is the normal value α, the load following operation is performed in the fuel cell unit 11 when the demand power exceeding the normal value α is generated on the load E side. On the other hand, as long as the demand power does not exceed the increase value β1, even if the demand power exceeds the normal value α by switching the minimum power purchase to the increase value β1 larger than the normal value α by the threshold switching unit 13, the fuel cell unit 11 can shift to a standby state without performing load following operation. Therefore, it is possible to selectively suppress power generation of the fuel cell unit 11 without requiring the fuel cell unit 11 to be stopped. In addition, power generation of the fuel cell unit 11 can be suppressed by adding a small function without requiring a significant specification change.

  In the present embodiment, the threshold switching unit 13 switches the minimum power purchase power according to the time zone. As a result, the power supply system 100 is configured such that the minimum purchased power becomes the increased value β1 in an arbitrary time zone, and the power generation of the fuel cell unit 11 in that time zone can be suppressed.

  In the night time zone, the demand power is often small, and when the fuel cell unit 11 performs the load following operation with respect to the small demand power, the operation efficiency of the fuel cell unit 11 deteriorates and the economic efficiency is impaired (the above condition) 2). In general, there may be a case where the power purchase fee for the power supplied from the system power supply 2a is discounted (in the case of the above condition 1) in the night time zone. In this regard, in the present embodiment, switching may be performed so that the minimum power purchase power is set to the increase value β1 in at least a part of the night time zone. As a result, the power generation of the fuel cell unit 11 can be suppressed during the time period, the operation of the fuel cell unit 11 with poor operating efficiency can be suppressed, and the power supplied from the inexpensive system power supply 2a can be used preferentially. As a result, economic merit can be obtained.

  In the daytime time zone, power can be supplied by the solar power generation system 2b. When the power generated by this solar power generation is used preferentially, the operation cost of the entire power supply system 100 can be reduced (for example, the above-mentioned (Condition 3). In this regard, in the present embodiment, switching may be performed so that the minimum power purchase power is set to the increase value β1 in at least some of the daytime hours. Thereby, the power generation of the fuel cell unit 11 can be suppressed during the time period, and the power of the solar power generation can be used preferentially, and economic merit can be obtained.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the description of the present embodiment, points that are different from the first embodiment will be described, and redundant description will be omitted.

  FIG. 2 is a schematic configuration diagram showing a power supply system 200 according to the second embodiment. As shown in FIG. 2, the power supply system 200 is different from the power supply system 100 (see FIG. 1) in that it further includes a current detection unit 20 and a power storage unit (second power storage unit) 21.

  The current detection unit 20 is configured in the same manner as the current detection unit 15. The current detection unit 20 is provided closer to the load E than the connection unit 3 in the main line LM. The current detection unit 20 is electrically connected to the power storage unit 21 and transmits the current value of the detected current to the power storage unit 21.

  The electrical storage part 21 is comprised with the storage battery, and performs charge and discharge of electric power. The power storage unit 21 is connected to the load E side of the main line LM with respect to the connection unit 3 with the fuel cell system 10. Specifically, the power storage unit 21 is connected via the connection unit 4 between the current detection unit 20 and the load E in the trunk line LM. The power storage unit 21 performs charging using the power supplied from the power supply source 2 or using the power supplied from the power supply source 2 and the power generation output of the fuel cell system 10. The power storage unit 21 discharges the stored power stored by the charging to the load E side via the connection unit 4 and the trunk line LM.

  The power storage unit 21 calculates the power flow at the position where the current detection unit 20 is disposed, for example, in the same manner as the control unit 12. And the electrical storage part 21 discharges so that load follow operation may be carried out, when the said tidal power is larger than the electrical storage part discharge threshold value. On the other hand, power storage unit 21 is placed in a discharge stopped state without discharging when the power flow is equal to or lower than the discharge threshold for the power storage unit. The storage unit discharge threshold is set in advance as the minimum electric power purchase. As the minimum electric power purchased by the power storage unit 21, for example, the normal value α may be used from the viewpoint of preventing reverse power flow. The load following operation of the power storage unit 21 is an operation of discharging from the power storage unit 21 so as to follow the demand power on the load E side with respect to the connection unit 4.

  The power supply system 200 is different in that the control unit 12 includes a threshold switching unit 23 instead of the threshold switching unit 13 (see FIG. 1). The threshold switching unit 23 has the following functions instead of or in addition to the functions described above in the threshold switching unit 13. That is, the threshold switching unit 23 switches the minimum power purchase between the normal value α and the increase value (second value) β2. Increase value β2 is set to be larger than the charging power of power storage unit 21 (power required for charging). For example, when the charging power of the power storage unit 21 is 3000 W, the increase value β2 is 8000 W.

  FIG. 3A is a diagram illustrating an example of a control map that is referred to when the threshold power switching unit 23 switches the minimum electric power purchase. In the example of Fig.3 (a), the case where the charging time of the electrical storage part 21 is set to the midnight time zone (here 0:00 to 2:00) is illustrated. According to the example illustrated in FIG. 3A, the threshold switching unit 23 switches the minimum power purchase so that the increase value β2 is obtained in a time zone including the charging time zone of the power storage unit 21. Specifically, the minimum power purchase power is set to the normal value α in the time zone from 6:00 to 20:00, and the time from 20:00 to 6:00, which is the night time zone when the power purchase fee of the system power supply 2a is cheaper. In the band, the minimum purchased power is set to an increase value β2.

  Accordingly, for example, when the charging power of the power storage unit 21 is 3000 W and the increase value β2 is 8000 W, the charging time of the power storage unit 21 is set to 8000 W or more in the time zone of 20:00 to 0:00 (0 to 00 to 00). 2:00), the power generation output of the fuel cell unit 11 is reduced if the power E is not consumed by the load E in the time zone of 2,000 W or more and 2:00 to 6:00, and the power generation output is less than or equal to a predetermined output. At this time, the fuel cell unit 11 is in a standby state without supplying power, and power is supplied only from the power supply source 2.

  FIG. 3B is a diagram illustrating another example of the control map that is referred to when the minimum power purchase power is switched in the threshold switching unit 23. In the example of FIG.3 (b), the case where the charging time of the electrical storage part 21 is set to 13: 0 to 15:00 with large solar radiation amount in the daytime time slot | zone is illustrated. According to the example illustrated in FIG. 3B, the threshold switching unit 23 switches the minimum purchased power so that the increase value β2 is obtained in a time zone including the charging time zone of the power storage unit 21. Specifically, the lowest power purchase power is set to the normal value α in the time zone from 15:00 to 13:00, and the solar power generation system 2b has a large power generation amount at 13:00, which is an afternoon time zone. In the time zone of 15:00, the minimum power purchase power is set to an increase value β2.

  Accordingly, for example, when the charging power of the power storage unit 21 is set to 3000 W and the increase value β2 is set to 8000 W, the fuel cell unit 11 does not consume 5000 W or more of power in the time zone from 13:00 to 15:00. When the generated power output is reduced and the generated power output is less than or equal to the predetermined output, the fuel cell unit 11 is in a standby state without supplying power, and is fed from only the power supply source 2.

  As described above, also in the present embodiment, it is possible to selectively suppress the power generation of the fuel cell unit 11 by adding a slight function without requiring the operation stop of the fuel cell unit 11 and without requiring a significant specification change.

  Further, when the minimum power purchase power is equal to or less than the charging power of the power storage unit 21, for example, when the power of the power supply source 2 can reduce the operation cost of the entire power supply system 100 (in the conditions 1 and 2 described above) Even when the power storage unit 21 is charged, there is a concern that the fuel cell unit 11 may always perform load following operation. In this regard, in the present embodiment, since the increase value β2 is larger than the charging power of the power storage unit 21, the power demand increases even when the power storage unit 21 is charged by switching the minimum power purchase to the increase value β2. As long as the value does not exceed, the fuel cell unit 11 can be shifted to the standby state.

  As a result, in the switching of the minimum electric power purchase shown in FIG. 3A, the late-night electric power at which the electric power purchase price of the system power supply 2a is reduced is preferentially used for charging the power storage unit 21, and economic merit is easily generated. be able to. In addition, in the switching of the minimum electric power purchase shown in FIG. 3B, the power generation output of the solar power generation system 2b is preferentially used for charging the power storage unit 21 in the daytime period, and economic merit is easily generated. it can. That is, each of the power storage unit 21, the solar power generation system 2b, and the fuel cell system 10 can be effectively operated.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the description of the present embodiment, points that are different from the first embodiment will be described, and redundant description will be omitted.

  FIG. 4 is a schematic configuration diagram illustrating a power supply system 300 according to the third embodiment. As shown in FIG. 4, the power supply system 300 is different from the power supply system 100 (see FIG. 1) in that it further includes a current detection unit 30 and a power storage unit (first power storage unit) 31.

  The current detection unit 30 is configured in the same manner as the current detection unit 15. The current detection unit 30 is provided closer to the power supply source 2 than the current detection unit 15 in the main line LM. The current detection unit 30 is electrically connected to the power storage unit 31, and transmits the detected current value of the current to the power storage unit 31.

  The electrical storage part 31 is comprised with the storage battery, and performs charge and discharge of electric power. The power storage unit 31 is connected to the power supply source 2 side from the current detection unit 15 in the trunk line LM. Specifically, the power storage unit 31 is connected via the connection unit 5 between the current detection unit 30 and the current detection unit 15 in the trunk line LM. The power storage unit 31 performs charging using the power supplied from the power supply source 2. In addition, the power storage unit 31 discharges the stored power stored by the charging to the load E side via the connection unit 5 and the trunk line LM.

  The power storage unit 31 calculates the power flow at the position where the current detection unit 30 is disposed, for example, in the same manner as the control unit 12. And the electrical storage part 31 discharges so that load follow operation may be carried out, when the said tidal power is larger than the electrical storage part discharge threshold value. On the other hand, when the tidal power is equal to or less than the discharge threshold for the power storage unit, the power storage unit 31 is in a discharge stopped state without discharging. The storage unit discharge threshold is set in advance as the minimum electric power purchase. As the minimum electric power purchased by the power storage unit 21, for example, the normal value α may be used from the viewpoint of preventing reverse power flow. The load following operation of the power storage unit 21 is an operation of discharging from the power storage unit 31 so as to follow the demand power on the load E side with respect to the connection unit 5. As illustrated in FIG. 4, the power storage unit 31 may include a power storage amount transmission unit 31 a that transmits information related to the power storage amount (remaining capacity) to the control unit 12 in a wired or wireless manner.

  The power supply system 300 is different in that the control unit 12 includes a threshold switching unit 33 instead of the threshold switching unit 13 (see FIG. 1). The threshold switching unit 33 may be added with the following function instead of or in addition to the above-described function of the threshold switching unit 13. That is, for example, when the power storage unit 31 includes the power storage amount transmission unit 31a, the threshold value switching unit 33 acquires information on the power storage amount from the power storage unit 31, and when the power storage amount is greater than a certain remaining amount (a certain remaining amount). The minimum power purchase power may be switched so that the minimum power purchase power is set to the increase value β1 (when there is more surplus). The constant remaining amount is, for example, a value that takes into account a predetermined margin for the minimum amount of power required for charging the power storage unit 31. As the constant remaining amount, for example, about 50% of the full charge amount can be set.

  As described above, also in the present embodiment, it is possible to selectively suppress the power generation of the fuel cell unit 11 by adding a slight function without requiring the operation stop of the fuel cell unit 11 and without requiring a significant specification change.

  In general, depending on the power demand balance, the power demand pattern, and the like of the day, the power stored in the power storage unit 31 that is charged by using late-night power at a low price for power purchase from the system power supply 2a may be largely left. In order to effectively use the power storage unit 31, it is considered that this stored power should be discharged to a certain remaining amount by the next charging time. In the present embodiment, since the fuel cell system 10 is installed on the downstream side (load E side) of the power storage unit 31, the fuel cell system 10 is likely to be preferentially discharged, but the power storage amount of the power storage unit 31 is constant. Since it is possible to set the minimum purchased power to the increase value β1 when the remaining amount is larger than the remaining amount, the power generation of the fuel cell unit 11 is suppressed and the power stored in the power storage unit 31 can be used preferentially.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. The present invention is modified without departing from the scope described in the claims or applied to others. It may be.

  For example, in the above embodiment, the specific values of the first value and the second value are not limited, and various values are adopted as long as the first value and the second value larger than the first value. can do. The power supply system 200 of the second embodiment includes the power storage unit 21 and the current detection unit 20, and the power supply system 300 of the third embodiment includes the power storage unit 31 and the current detection unit 30, both of which are provided. A power supply system (that is, a power supply system combining the second embodiment and the third embodiment) may be used.

  Note that the present invention can be understood not only as the power supply system 100 and the control device 1 but also as an operation method of the power supply system 100 and the control device 1.

  DESCRIPTION OF SYMBOLS 1 ... Control apparatus, 2 ... Power supply source, 2a ... System power supply, 2b ... Solar power generation system, 3 ... Connection part, 11 ... Fuel cell part, 12 ... Control part, 13 ... Threshold switching part, 15 ... Current detection part , 21 ... power storage unit (second power storage unit), 31 ... power storage unit (first power storage unit), 100 ... power supply system, E ... load, LM ... main line.

Claims (7)

A fuel cell unit connected to a trunk line connected to a load from a power supply source;
A current detection unit that is provided closer to the power supply source than the connection with the fuel cell unit in the main line, and detects a current flowing through the main line;
A control unit for controlling the operation of the fuel cell unit based on power flow corresponding to the current detected by the current detection unit,
The controller is
When the power flow is larger than a discharge threshold, the fuel cell unit generates power so that the power generation output of the fuel cell unit follows the demand power on the load side of the connection unit,
When the power flow is less than or equal to the discharge threshold, when the power generation output by the fuel cell unit is reduced and the power generation output becomes a predetermined output or less, the fuel cell unit is placed in a standby state,
A power supply system further comprising a threshold switching unit that switches the discharge threshold between at least a first value and a second value that is greater than the first value.   The power supply system according to claim 1, wherein the threshold switching unit switches the discharge threshold according to a time zone. The power supply source includes a system power supply,
The power supply system according to claim 2, wherein the threshold switching unit switches the discharge threshold to be set to the second value in at least a part of a night time zone. The power supply source includes a solar power generation system,
The power supply system according to claim 2 or 3, wherein the threshold switching unit switches the discharge threshold to be set to the second value in at least a part of a daytime period. A first power storage unit connected to the power supply source side than the current detection unit in the main line and capable of charging and discharging power;
The power supply system according to claim 1, wherein the threshold value switching unit switches the discharge threshold value to be set to the second value when the amount of power stored in the first power storage unit is greater than a certain remaining amount. A second power storage unit that is connected to the load side of the main line and connected to the load side of the fuel cell unit, and capable of charging and discharging power;
The power supply system according to any one of claims 1 to 5, wherein the second value is larger than charging power of the second power storage unit. A fuel cell unit connected to a trunk line connected to a load from a power supply source;
A control device mounted on a power supply system including a current detection unit configured to detect a current flowing through the main line, provided on the power supply source side of a connection with the fuel cell unit in the main line,
A control unit that controls the operation of the fuel cell unit based on the power flow corresponding to the current detected by the current detection unit,
The controller is
When the power flow is larger than a discharge threshold, the fuel cell unit generates power so that the power generation output of the fuel cell unit follows the demand power on the load side of the connection unit,
When the power flow is less than or equal to the discharge threshold, when the power generation output by the fuel cell unit is reduced and the power generation output becomes a predetermined output or less, the fuel cell unit is placed in a standby state,
A control device further comprising a threshold switching unit that switches the discharge threshold between at least a first value and a second value that is greater than the first value.

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