JP5897899B2 - Power control system, control device, and power control method - Google Patents

Description

  The present invention relates to a power control system, a control device, and a power control method for controlling a fuel cell and a storage battery.

  In recent years, fuel cells, which are a type of distributed power source, have been widely used by power consumers. A fuel cell generates power by a chemical reaction between hydrogen extracted from gas and oxygen in the air.

  Since the output of the fuel cell is variable within the range up to the rated output (that is, the maximum output), the output of the fuel cell is increased / decreased in accordance with the increase / decrease of the power consumption of the load device (hereinafter referred to as the power load) It is common to apply “load following control”.

  In addition, it is known that when a fuel cell is operated at a low output, the power generation efficiency is lowered.

  Therefore, in order to prevent the fuel cell from operating at a low output, a power control system that uses the fuel cell in combination with a storage battery has been proposed (see Patent Document 1). The power control system described in Patent Document 1 operates a fuel cell intermittently at a rated output, and charges the storage battery with surplus power when the power load is smaller than the rated output of the fuel cell during operation of the fuel cell. When power is stopped, the insufficient power is compensated by discharging the storage battery.

JP-A-5-182675

  The power control system described in Patent Document 1 has the following problems. Specifically, since the fuel cell takes a long time to stop and start, control for repeating the stop and start is not appropriate.

  Therefore, an object of the present invention is to provide a power control system, a control device, and a power control method for performing operation control of a fuel cell with higher efficiency.

  In order to solve the above-described problems, the present invention has the following features.

  The power control system of the present invention is a power control system that controls a fuel cell (for example, the fuel cell 13) and a storage battery (for example, the storage battery 22), and uses the power used for charging a power load and the storage battery. A fuel cell control unit (for example, the fuel cell control unit 12) that controls the fuel cell to output, and a storage battery control unit (for example, the HEMS control unit 32) that controls the storage battery, and the storage battery control unit Is characterized by performing continuous charge control for continuously charging the storage battery so as to keep the output of the fuel cell at a predetermined value or more during a predetermined period when the power load is small.

  In the power control system described above, the storage battery control unit may charge the storage battery until full charge by the continuous charge control.

  In the power control system described above, the fuel cell linearly changes the power generation efficiency in the low output region, and the power generation efficiency becomes substantially saturated in the high output region. It may be greater than or equal to the value near the boundary with the high output region.

  In the power control system described above, the storage battery control unit may determine whether to execute or stop the continuous charge control based on a chargeable amount of the storage battery at the start of the predetermined period.

  In the power control system described above, the storage battery control unit is configured so that the output of the fuel cell is larger at the end of the predetermined period than at a point in the middle of the predetermined period. The amount of charge may be controlled.

  In the power control system described above, the storage battery control unit includes an acquisition unit (for example, a HEMS control unit 32; step S15) that acquires a chargeable amount of the storage battery at the start of the predetermined period, and a power load in the predetermined period. Based on prediction means (for example, HEMS control unit 32; step S11) for predicting a pattern, the chargeable amount acquired by the acquisition means, and the power load pattern predicted by the prediction means, the predetermined period Determining means (for example, HEMS control unit 32; step S16) for determining a charging schedule of the storage battery.

  The control device of the present invention is a control device (for example, HEMS30) used in a power control system that controls a fuel cell and a storage battery, and has a storage battery control unit (for example, a HEMS control unit 32) that controls the storage battery. The fuel cell outputs electric power used for electric power load and charging of the storage battery, and the storage battery control unit maintains the output of the fuel cell at a predetermined value or more during a predetermined period when the electric power load is small. Thus, the continuous charge control which charges the said storage battery continuously is performed.

  The power control method of the present invention is a power control method for controlling a fuel cell and a storage battery, wherein the fuel cell is controlled to output power used for power load and charging of the storage battery. A step B for controlling the storage battery, wherein the step B continuously charges the storage battery so as to keep the output of the fuel cell at a predetermined value or higher during a predetermined period when the power load is small. Control is performed.

  ADVANTAGE OF THE INVENTION According to this invention, the power control system, control apparatus, and power control method which perform operation control of a more efficient fuel cell can be provided.

It is a block diagram of the electric power feeding system which concerns on 1st Embodiment and 2nd Embodiment. An example of the characteristic of the power generation efficiency with respect to the output electric power of a fuel cell is shown. It is a flowchart of the electric power control method which concerns on 1st Embodiment and 2nd Embodiment. It is a graph for demonstrating the specific example of 1st Embodiment and 2nd Embodiment.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings according to the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

[First Embodiment]
(System configuration)
FIG. 1 is a block diagram of a power feeding system according to the present embodiment. In FIG. 1, the solid line between blocks shows a power line, and the broken line between blocks shows a control line.

  As shown in FIG. 1, the power supply system according to the present embodiment includes a system power supply 1, a plurality of load devices 2, a fuel cell unit 10, a storage battery unit 20, and a house energy management system (HEMS) 30. The plurality of load devices 2, the fuel cell unit 10, the storage battery unit 20, and the HEMS 30 are provided in a consumer who receives supply of alternating current (AC) power from the system power supply 1 of the power company.

  Between the system power supply 1 and the plurality of load devices 2, a system power line L1 for supplying output power of the system power supply 1 to the plurality of load devices 2 is provided. The plurality of load devices 2 are devices that operate by consuming electric power, for example, home appliances.

  The power output line L2 of the fuel cell unit 10 merges with the system power line L1 at the merge point P1. The power input / output line L3 of the storage battery unit 20 merges with the system power line L1 at the junction P2. In FIG. 1, the junction P2 is provided on the grid power supply 1 side with respect to the junction P1, but the junction P2 may be provided on the load device 2 side with respect to the junction P1.

  On the system power line L1 between the junctions P1 and P2 and the system power supply 1, a current sensor 41 for measuring the current flowing through the system power line L1 is provided. Further, a current sensor 42 for measuring a current flowing through the system power line L1 is provided on the system power line L1 between the junctions P1 and P2 and the plurality of load devices 2.

  The fuel cell unit 10 includes a fuel cell communication unit 11, a fuel cell control unit 12, and a fuel cell 13.

  The fuel cell communication unit 11 performs communication with each of the current sensor 41 and the HEMS 30 in a wired or wireless manner. When the communication is performed wirelessly, the fuel cell communication unit 11 can be configured by, for example, a Zigbee (registered trademark) communication module. The fuel cell communication unit 11 receives the current value transmitted from the current sensor 41. Further, the fuel cell communication unit 11 receives a control command transmitted from the HEMS 30 and transmits information related to the fuel cell 13 to the HEMS 30.

  The fuel cell control unit 12 controls the fuel cell 13 to perform the load following operation based on the power value calculated from the current value received by the fuel cell communication unit 11 and the voltage value measured by the fuel cell 13. . For example, the fuel cell control unit 12 sets the target output power of the fuel cell 13 so that the power purchase from the system power supply 1 becomes a predetermined value (for example, zero), and the output of the fuel cell 13 becomes the target output power. Thus, the fuel cell 13 is controlled. Further, the fuel cell control unit 12 controls communication in the fuel cell communication unit 11.

  The fuel cell 13 performs an interconnection operation with the system power supply 1. The fuel cell 13 includes a fuel cell main body 13a and a fuel cell power conditioner (PCS) 13b.

  The fuel cell main body 13a generates power by a chemical reaction between hydrogen extracted from natural gas or the like and oxygen in the air, and outputs direct current (DC) power to the fuel cell PCS 13b. The amount of power generation in the fuel cell main body 13a varies depending on the amount of gas and air consumed in the fuel cell main body 13a. The amounts of gas and air are controlled by the fuel cell control unit 12. For example, the fuel cell body 13a is a solid oxide fuel cell (SOFC) or a molten carbonate fuel cell (MCFC) that requires high temperature operation.

  The fuel cell PCS 13b converts DC power from the fuel cell main body 13a into AC, and outputs AC power via the power output line L2. In the present embodiment, it is assumed that the power output (reverse power flow) to the system power supply 1 is not permitted for the output power of the fuel cell 13.

  The storage battery unit 20 includes a storage battery communication unit 21 and a storage battery 22.

  The storage battery communication unit 21 performs communication with the HEMS 30 in a wired or wireless manner. When communicating with the HEMS 30 wirelessly, the storage battery communication unit 21 can be configured by, for example, a Zigbee (registered trademark) communication module. The storage battery communication unit 21 receives a control command transmitted from the HEMS 30 or transmits information related to the storage battery 22 to the HEMS 30. Here, the control commands transmitted from the HEMS 30 include a charge command for instructing charging and a discharge command for instructing discharging. Examples of the information related to the storage battery 22 include a storage amount that is the amount of power stored in the storage battery 22.

  The storage battery 22 performs an interconnection operation with the system power supply 1. The storage battery 22 includes a storage battery main body 22a and a storage battery PCS22b.

  The storage battery body 22a charges the DC power output from the storage battery PCS22b. Moreover, the storage battery main body 22a outputs DC power to the storage battery PCS22b by discharging. Charging / discharging in the storage battery main body 22a is controlled according to a control command that the storage battery communication unit 21 receives from the HEMS 30.

  The storage battery PCS 22b converts AC power input via the power input / output line L3 into DC and outputs DC power to the storage battery body 22a when the storage battery body 22a is charged. In addition, the storage battery PCS 22b converts the DC power from the storage battery body 22a into AC when the storage battery body 22a is discharged, and outputs the AC power through the power input / output line L3. In the present embodiment, it is assumed that power output (reverse power flow) to the system power supply 1 is not permitted for the output power of the storage battery 22.

  When the storage battery body 22a is charged, the AC power input to the storage battery PCS 22b via the power input / output line L3 increases. In this case, the fuel cell control unit 12 performs control to increase the output power of the fuel cell 13 so that the power purchased from the system power supply 1 is set to a predetermined value (zero).

  The HEMS 30 performs power management at the consumer. The HEMS 30 includes a HEMS communication unit 31, a HEMS control unit 32, and a storage unit 33.

  The HEMS communication unit 31 performs communication with each of the current sensor 42, the fuel cell unit 10, and the storage battery unit 20 in a wired or wireless manner. When performing these communications wirelessly, the HEMS communication part 31 can be comprised by a Zigbee (trademark) communication module, for example. The HEMS communication unit 31 receives a current value transmitted from the current sensor 42. Moreover, the HEMS communication part 31 transmits the control command with respect to each of the fuel cell unit 10 and the storage battery unit 20, or receives the information regarding each of the fuel cell unit 10 and the storage battery unit 20.

  The HEMS control unit 32 manages the power load that is the power consumption of the load device 2, the amount of power sold to the system power source 1, and the amount of power purchased from the system power source 1, and performs control for power saving on the load device 2. Or go. Further, the HEMS control unit 32 remotely controls the fuel cell 13. In the present embodiment, the HEMS control unit 32 corresponds to a fuel cell control unit that controls the fuel cell 13.

  The storage unit 33 stores information used for control by the HEMS control unit 32. The storage unit 33 stores a predicted power load pattern (hereinafter, referred to as “load pattern”) indicating a power load for each time period in a day. The predicted load pattern for each time period of the day is created by the HEMS control unit 32 based on the past actual load value. Moreover, the memory | storage part 33 has memorize | stored beforehand the largest electrical storage amount of the storage battery 22 (storage battery main body 22a).

  In the present embodiment, the fuel cell control unit 12 and the HEMS control unit 32 constitute a power control system that controls the fuel cell 13 and the storage battery 22.

  The fuel cell control unit 12 controls the fuel cell 13 so as to output electric power used for electric power load and charging of the storage battery 22. The HEMS control unit 32 performs continuous charge control for continuously charging the storage battery 22 until full charge so as to keep the output of the fuel cell 13 at a constant value in a predetermined period when the power load is small.

  Here, the fixed value of the output of the fuel cell 13 is a rated output. Moreover, the predetermined period with a small electric power load is a period when the electric power load continues below the threshold, and is, for example, night (or midnight). Hereinafter, a predetermined period during which continuous charge control is to be performed is referred to as a “continuous charge period”. The full charge means a charge amount that can be regarded as a full charge state, and a state where the upper limit of the use range of the storage battery 22 (x% to y% of full charge) is reached may be regarded as full charge.

  By continuously charging the storage battery 22 so as to keep the output of the fuel cell 13 at a constant value during the continuous charging period, the fuel cell 13 is operated at a low output without repeating the stop and start of the fuel cell 13. Can be prevented.

  FIG. 2 shows an example of the characteristics of the power generation efficiency with respect to the output power of the fuel cell 13. The power generation efficiency is the ratio of the output (power generation amount) of the fuel cell 13 to the gas consumption amount of the fuel cell 13.

  As shown in FIG. 2, in the fuel cell 13, the power generation efficiency changes linearly in the low output region, and the power generation efficiency becomes substantially saturated in the high output region. That is, when the fuel cell 13 reaches a certain output (hereinafter referred to as “power generation efficiency saturation point”), the power generation efficiency does not change so much. The power generation efficiency saturation point is a value near the boundary between the low output region and the high output region of the fuel cell 13.

  Therefore, the HEMS control unit 32 continuously charges the storage battery 22 so as to keep the output of the fuel cell 13 at or above the power generation efficiency saturation point during the continuous charging period. Thereby, it becomes possible to drive | operate with high electric power generation efficiency, suppressing the output of the fuel cell 13, and a utility bill is reduced. Moreover, deterioration of the fuel cell 13 can be prevented by avoiding operation at a low output.

  However, in order to keep the output of the fuel cell 13 at the power generation efficiency saturation point during the continuous charging period, the chargeable amount of the storage battery 22 at the start of the continuous charging period needs to be a predetermined value or more. Here, the chargeable amount is a difference between the maximum charged amount of the storage battery 22 (storage battery main body 22a) and the current charged amount.

  Therefore, the HEMS control unit 32 may determine whether to execute or stop the continuous charge control based on the chargeable amount of the storage battery 22 at the start of the continuous charge period. Specifically, when the chargeable amount of the storage battery 22 at the start of the continuous charging period is less than a predetermined value, the HEMS control unit 32 may stop the continuous charging control. Or the HEMS control part 32 may perform discharge control of the storage battery 22 before the start of a continuous charge period so that the chargeable amount at the time of the start of a continuous charge period may become more than predetermined value.

(Operation flow)
FIG. 3 is a flowchart of the power control method according to the present embodiment. This flow is performed every day, for example. In addition, this flow is acquired in step S11 in which the load pattern in at least the continuous charging period is acquired in the HEMS control unit 32, step S15 in which the chargeable amount of the storage battery 22 is acquired at the start of the continuous charging period, and step S11. Step S16 which determines the charge schedule of the storage battery 22 in a continuous charge period based on the made load pattern and the chargeable amount acquired at Step S15.

  As shown in FIG. 3, in step S <b> 11, the HEMS control unit 32 acquires the load pattern Pl [i] (i = 0, 1, 2,..., 23:00) for each time period from the storage unit 33. To do.

  In step S12, the HEMS control part 32 determines a continuous charging period based on the load pattern according to the 1 time slot | zone acquired by step S11. For example, the maximum output (rated output) of the fuel cell 13 is 0.7 kW, Pl [i] is maintained at 0.7 kW when i = 6, 7,..., 23:00, and i = 0, 1,. , 5 o'clock, if it is a small value below 0.7 kW, i = 0, 1, ..., 5 o'clock is determined as the continuous charging period.

  In step S <b> 13, the HEMS control unit 32 performs charge / discharge control of the storage battery 22. For example, the HEMS control unit 32 operates the fuel cell 13 at the rated output at i = 6, 7,..., 23, while the storage battery 22 supplies insufficient power when the power load is larger than the rated output of the fuel cell 13. When the power load is smaller than the rated output of the fuel cell 13, the storage battery 22 is controlled to be charged.

  In step S14, the HEMS control unit 32 checks whether or not the continuous charging period determined in step S12 has started. Specifically, it is confirmed whether or not the current time is the start time of the continuous charging period. If the continuous charging period has not yet started (step S14; NO), the HEMS control unit 32 returns the process to step S13, and if the continuous charging period has started (step S14; YES), the process proceeds to step S15. Proceed to

  In step S <b> 15, the HEMS control unit 32 acquires the amount of power stored in the storage battery 22. For example, the HEMS control unit 32 obtains the storage amount by inquiring the storage battery 22 about the storage amount via the HEMS communication unit 31 and the storage battery communication unit 21.

  In step S16, the HEMS control part 32 is based on the load pattern according to the time slot | zone of the day acquired by step S11, the electrical storage amount acquired by step S15, and the largest electrical storage amount memorize | stored in the memory | storage part 33. Then, the charging schedule in the continuous charging period is determined. For example, the discharge schedule is determined as follows.

Assuming that the power load is Pl and the charge amount is Pc, the output power Ps that the fuel cell 13 should output is
Ps = Pl + Pc (1)
It becomes. On the other hand, when Pl exceeds the rated output (maximum output) Ps_max of the fuel cell 13 in the (normal) charge / discharge period other than the continuous charge period, the output power Ps of the fuel cell 13 and the discharge amount Pd of the storage battery 22 are:
Ps = Ps_max
Pd = Pl−Ps_max (2)
It becomes.

  When the storage amount at the start of the continuous charging period is Pa and the maximum storage amount is Pm, the HEMS control unit 32 determines a charging schedule Pc [i] (i = 0, 1,..., 5) that satisfies the following equation. To do.

       Pl [i] + Pc [i] = α (i = 0,1,…, 5)

  Here, α corresponds to output power equal to or higher than the power generation efficiency saturation point described above. Thus, in each time zone of the continuous charging period, the sum of the power load and the charge amount is constant (that is, α).

  In step S17, the HEMS control part 32 performs charge control with respect to the storage battery 22 based on Pc [i] (i = 0, 1, ..., 5) of each time slot | zone determined by step S16. Basically, the HEMS control unit 32 performs charge control according to the charge schedule Pc [i] (i = 0, 1,..., 5) determined in step S16, but the actual power load and the predicted load pattern. If the distance between the charging schedule and the charging schedule is large, the charging schedule Pc [i] may be modified so that the formula (3) is satisfied.

  In step S18, the HEMS control unit 32 checks whether or not the continuous charging period determined in step S12 has ended. Specifically, it is confirmed whether or not the current time is the end time of the continuous charging period. The HEMS control unit 32 returns the process to step S17 if the continuous charging period has not yet ended (step S18; NO), and ends this flow if the continuous charging period has ended (step S18; YES). To do.

[Second Embodiment]
In the first embodiment described above, the HEMS control unit 32 generates the output of the fuel cell 13 by generating a constant total power load and charge amount (that is, α) in each time zone of the continuous charge period. The efficiency saturation point α was maintained.

  On the other hand, in this embodiment, the HEMS control part 32 is the storage battery in continuous charge control so that the output of the fuel cell 13 becomes larger at the end of the continuous charge period than at the time in the middle of the continuous charge period. 22 charge amount is controlled. For example, the HEMS control unit 32 sets α in equation (3) to α [i] (i = 0, 1,..., 5), and increases α as i increases.

  Further, the HEMS control unit 32 acquires (predicts) the power load immediately after the end of the continuous charging period based on the load pattern, and the temperature of the fuel cell main body 13a is suitable for the power load immediately after the end of the continuous charging period. Bring to temperature.

  In this way, by performing the charging control so as to increase the output power of the fuel cell 13 with the passage of time in the continuous charging period, the fuel cell body 13a can be kept at a high temperature at the end of the continuous charging period. Thereby, high power generation efficiency can be obtained after the end of the continuous charging period.

[Concrete example]
Next, specific examples of the first embodiment and the second embodiment described above will be described. FIG. 4 is a graph for explaining a specific example of the first embodiment and the second embodiment. FIG. 4 illustrates a comparative example, a specific example of the first embodiment, and a specific example of the second embodiment.

  As shown in FIG. 4, the comparative example shows a case where the fuel cell 13 operates at the rated output (maximum output) from the start of the continuous charging period and charges the storage battery 22 with the surplus. In the comparative example, the storage battery 22 becomes fully charged at 3 o'clock and cannot be charged any more, so the fuel cell 13 performs a load following operation so as to follow the power load.

  When such a load following operation is performed, the output of the fuel cell 13 decreases as the power load decreases, so the fuel cell 13 operates in a state where the power generation efficiency is low, and the utility cost cannot be reduced. . Moreover, the fuel cell 13 deteriorates by performing the operation at a low output.

  On the other hand, in the first embodiment, the HEMS control unit 32 continuously keeps the storage battery 22 until fully charged so as to keep the output of the fuel cell 13 at the power generation efficiency saturation point from the start to the end of the continuous charge period. Recharge. As a result, the fuel cell 13 can always be operated with high power generation efficiency, and utility costs are reduced. Further, since the operation with the high output power is continued, the deterioration of the fuel cell 13 is prevented. As a result, a better load following capability is realized as compared with when the vehicle is operated at a low output.

  In 2nd Embodiment, the HEMS control part 32 is the charge amount of the storage battery 22 in continuous charge control so that the output of the fuel cell 13 becomes larger at the end of the continuous charge period than at a point in the middle of the continuous charge period. To control. As a result, the fuel cell 13 can always be operated with high power generation efficiency, and utility costs are reduced. Moreover, the deterioration of the fuel cell 13 is prevented by continuing the operation at a high output. Furthermore, since the fuel cell body 13a can be kept at a high temperature at the end of the continuous charging period, high power generation efficiency and high followability can be obtained even when high output power is required after the continuous charging period ends.

[Other Embodiments]
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the HEMS that is an energy management system (EMS) provided in units of houses has been described as an example. However, the HEMS is not limited to the HEMS, but BEMS that is provided in units of buildings, or a community such as a region. You may apply this invention to CEMS etc. which are EMS provided in a unit.

  Moreover, a control part may be provided in the fuel cell unit 10, and the said control part may perform the charge control which the HEMS control part 32 performed in 1st Embodiment and 2nd Embodiment mentioned above.

  L1 ... grid power line, L2 ... power output line, L3 ... power input / output line, P1, P2 ... confluence, 1 ... grid power supply, 2 ... load equipment, 10 ... fuel cell unit, 11 ... fuel cell communication unit, 12 DESCRIPTION OF SYMBOLS ... Fuel cell control part, 13 ... Fuel cell, 13a ... Fuel cell main body, 13b ... Fuel cell PCS, 20 ... Storage battery unit, 21 ... Storage battery communication part, 22 ... Storage battery, 22a ... Storage battery main body, 22b ... Storage battery PCS, 30 ... HEMS, 31 ... HEMS communication unit, 32 ... HEMS control unit, 33 ... storage unit, 41, 42 ... current sensor

Claims (7)

A power control system for controlling a fuel cell and a storage battery,
A fuel cell control unit for controlling the fuel cell to output electric power used for power load and charging of the storage battery;
A storage battery control unit for controlling the storage battery,
The storage battery control unit performs continuous charge control for continuously charging the storage battery until the storage battery is fully charged so that the output of the fuel cell is maintained at a predetermined value or more in a predetermined period when the power load is small. A power control system characterized by that. In the fuel cell, the power generation efficiency linearly changes in the low output region, and the power generation efficiency becomes substantially saturated in the high output region,
The power control system according to claim 1 , wherein the constant value is equal to or greater than a value near a boundary between the low output region and the high output region. The battery control unit on the basis of the chargeable amount of the battery at the start of the predetermined period, according to claim 1 or 2, characterized in that to determine or cancel executing the continuous charge control Power control system. The storage battery control unit controls the charge amount of the storage battery in the continuous charge control so that the output of the fuel cell is larger at the end of the predetermined period than at a point in the middle of the predetermined period. The power control system according to any one of claims 1 to 3 , wherein the power control system is characterized. The storage battery control unit
Obtaining means for obtaining a chargeable amount of the storage battery at the start of the predetermined period;
Predicting means for predicting a power load pattern in the predetermined period;
Determining means for determining a charging schedule of the storage battery in the predetermined period based on the chargeable amount acquired by the acquiring means and the power load pattern predicted by the predicting means. The power control system according to any one of claims 1 to 4 . A control device used in a power control system for controlling a fuel cell and a storage battery,
A storage battery control unit for controlling the storage battery;
The fuel cell outputs power used for power load and charging of the storage battery,
The storage battery control unit performs continuous charge control for continuously charging the storage battery until the storage battery is fully charged so that the output of the fuel cell is maintained at a predetermined value or more in a predetermined period when the power load is small. A control device characterized by that. A power control method for controlling a fuel cell and a storage battery,
Controlling the fuel cell to output power used for power load and charging of the storage battery; and
And step B for controlling the storage battery,
The step B performs continuous charge control for continuously charging the storage battery until the storage battery is fully charged so that the output of the fuel cell is maintained at a predetermined value or more in a predetermined period when the power load is small. A power control method characterized by the above.

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