JP2002198079A - Control device for fuel cell system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Conventionally, when a fuel cell is operated, the sum of the electricity rate and the fuel gas rate may be larger. An operation schedule creation unit (12) divides a day into a plurality of time zones at different times of unit prices of electricity rates,
In each time zone, the unit price of the electricity rate is compared with the unit price of the fuel cell 1 calculated by the unit price calculation unit 13,
When the unit price of electricity bill is the same as the unit price of power generation, storage battery 4
The operation schedule of the fuel cell 1 is created so as to charge the battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power generation system using a fuel cell and a method of operating the same.

[0002]

2. Description of the Related Art A fuel cell is an energy saving system that generates electric power by a chemical reaction between fuel gas and air to supply electric power and also supplies heat generated in the process of electric power generation.
Conventionally, the fuel cell operation method performs power load following operation that matches the amount of power generated by the fuel cell to the amount of power consumed by the power load.If the amount of power consumed exceeds the rated amount of power generated by the fuel cell, power is purchased from a commercial power source. Is generally used.

[0003] However, if the unit price of power generation by the fuel cell, that is, the cost of fuel gas required for the fuel cell to generate a unit amount of electric power, is not lower than the cost of purchasing commercial power from an electric power company or the like, the fuel must be used. There is no economic advantage to operating a battery system. At present, for example, the unit price of the electricity rate for all electrified houses under the jurisdiction of Tokyo Electric Power Company is 1
It is divided into three stages according to the time per day, and the difference between the late night time zone where the unit price of the electricity fee is the lowest and the daytime time zone where the unit price is the highest is more than five times in summer. On the other hand, in consideration of the cost of fuel gas and the power generation efficiency of the fuel cell, the power generation unit price of the fuel cell is a value between the unit price of the electricity rate in the late night hours and the unit price in the daytime hours. Therefore, there is no economic merit even if the fuel cell is operated at a time when the unit price of the electricity bill is low, such as at midnight.

At present, it is difficult to make the amount of power generated by the fuel cell follow the power load. This is because a time delay of the order of several minutes occurs in controlling the supply amount of the fuel gas to converge the power generation amount of the fuel cell to the target control value.
As a technique to cope with such a problem, a storage battery is prepared. When the power consumption is reduced, the battery is stored, and when the power consumption is increased, the battery is discharged. Some fuel cells maintain a constant power generation amount. As an example, there is a technology disclosed in JP-A-6-325774.

FIG. 6 shows a configuration diagram of the technique described in Japanese Patent Application Laid-Open No. 6-325774. 101 is a fuel cell, 102 is an inverter that converts DC power, which is the output of the fuel cell, into AC power, and 103 is a storage battery that charges DC power. 11
Reference numeral 0 denotes a control device having a control unit 111. 120, 121
Are electric power load, hot water supply load, and 131, 13 respectively.
Reference numerals 2 and 133 denote switches that operate in response to a command from the control unit 111. An external power supply 150 corresponds to a power company.

The operation will be described below. The fuel cell 101 operates at a constant power generation amount, and the power load 12
When the power consumption of 0 decreases, the switch 131 is connected, and the surplus power is charged to the storage battery 103. Conversely, when the power consumption of the power load 120 increases, the switch 132 is connected to discharge the storage battery 103 and supply the power to the power load 120. When the storage amount of the storage battery 103 becomes full,
Alternatively, when the charged amount is depleted, the control unit 111 outputs a control signal so that the amount of power generated by the fuel cell decreases or increases.

The control unit 111 issues a command to connect the switch 133, purchases cheap nighttime power from the external power supply 150, and charges the storage battery 103.

[0008]

However, in the above-described control device for a fuel cell system, a comparison is made between a unit price of power generation of the fuel cell and a power purchase cost that changes over time based on an electricity rate system of an electric power company or the like. However, there is a problem that the unit price of the electricity bill may be higher when the fuel cell is operated. For example, at midnight when the unit price of the electricity rate is low, the unit price of power generation of the fuel cell becomes higher, and it is more economical to stop the fuel cell and buy power from an external power supply. Furthermore, regarding the technology of JP-A-6-325774 public relations,
Depending on the power consumption of the power load, the storage capacity may be exhausted immediately before entering the daytime hours when the unit price of the electricity rate is high, and it may be necessary to buy high electricity during the daytime hours when the power consumption is high. There was a problem that the total of the charges would be high.

The present invention takes into account the above-described problems of the conventional control apparatus for a fuel cell system, and considers a fuel cell operating method that reflects a tariff system even if the power tariff system changes for each time zone in one day. By providing a schedule, the means for minimizing the sum of the electricity fee and the fuel gas fee as much as possible is provided.

[0010]

In order to solve the above problems, a fuel cell control device according to the present invention generates electric power and heat from fuel gas and air, and supplies electric power and heat to an electric load and a heat load, respectively. In a fuel cell system, a storage battery that accumulates a power generation output of a fuel cell, an operation schedule creation unit that determines a daily operation schedule, and controls a power generation output of the fuel cell and charging or discharging of the storage battery according to the operation schedule. The operation schedule creating unit sets the time period of the day to three time periods, that is, a high electricity time period, in which the unit price of the electricity rate is higher than the unit price of the fuel cell, and the unit price of the electricity rate. Is divided into an equivalent time zone in which the unit price of the fuel cell is the same as the unit price of the fuel cell, and a unit price of the electricity tariff in which the unit price of the fuel cell is lower than the unit price of the fuel cell, and In the electricity time period, the fuel cell generates the amount of power consumed by the power load, and in the equivalent time period, the fuel cell charges the unconsumed power to the storage battery, and in the low electricity time period, An operation schedule is created so that the fuel cell is stopped or operated at the first operation capacity.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a configuration diagram showing a configuration of a control device according to a first embodiment of the present invention. Reference numeral 1 denotes a fuel cell, 2 denotes an inverter for converting DC power output from the fuel cell into AC power, and 3 denotes a power consumption measuring unit for measuring power consumption of the power load 20. The power consumption measuring unit 3 is a power sensor, and may be built in the inverter 2. Reference numeral 4 denotes a storage battery that charges DC power, and can output the amount of stored power to the control device. 3
Reference numeral 0 denotes a switch necessary for purchasing electricity from the external power supply 50. The external power source 50 is a business entity that supplies and sells commercial power, such as a power company. Reference numerals 31 and 32 are switches necessary for charging and discharging the storage battery 4. In addition,
Reference numeral 21 denotes a heat load that utilizes heat output from the fuel cell 1.

Reference numeral 10 denotes a control unit, which includes a control unit 11, an operation schedule creation unit 12, a power generation unit price calculation unit 13, an electricity rate system storage unit 14, a fuel gas rate system storage unit 15, and a timer 19.

The electricity charge system storage unit 14 and the fuel gas charge system storage unit 15 store the unit price of the electricity charge and the unit price of the fuel gas charge for each time period of the day, respectively. The power generation unit price calculation unit 13 holds a performance table for obtaining the fuel gas input energy and the energy efficiency of the fuel cell 1 represented by the power generation efficiency and the hot water efficiency when the operation capacity of the fuel cell 1 is selected. 1 calculates the power generation unit price of the fuel cell as the cost required to generate the unit power amount.

The operation schedule creation unit 12 obtains the unit price of the fuel cell from the unit price calculation unit 13 and compares it with the unit price of the electric charge obtained from the electric charge system storage unit 14. Set a schedule.
The control unit 11 operates the fuel cell 1 in accordance with the operation schedule determined by the operation schedule creation unit 12, takes the current time from the timer 19, controls the power generation output of the fuel cell 1, and operates the switches 30, 31, and 32.

Next, the operation of the embodiment will be described.

[0016] Once a day, the control unit 11 determines an operation schedule of the fuel cell 1. It is preferable to determine the schedule at midnight when there is not much change in the power load 20 and there is no change in the unit price of the electricity bill. First, the power generation unit price calculation unit 13 calculates the power generation unit price of the fuel cell 1. The fuel gas rate system is acquired from the fuel gas rate system storage unit 15, and the unit price of power generation is estimated from the unit price of fuel gas and the energy efficiency of the fuel cell. At present, the unit price of the fuel gas does not change depending on the time of the day, and the unit price of the fuel gas used when determining the operation schedule of the fuel cell 1 is unique.

As the energy efficiency, for example, a value when the fuel cell 1 is operated at a half of the rated value is used. To further consider the amortization of the entire fuel cell system, the fuel cell system price per unit power generation, which is obtained by dividing the price of the fuel cell system by the assumed amortization period and the expected power generation per day, is calculated earlier. May be included in the power generation unit price. Assuming that the power generation efficiency at the time of rated operation of the fuel cell system is 30%, the hot water efficiency is 40%, the price is 500,000 yen, and 15 kWh per day is amortized for 15 years, the power generation unit price is 20 to 24 yen / kWh. . The power generation unit price calculation unit 13 outputs the power generation unit price of the fuel cell 1 to the operation schedule creation unit 12.

The operation schedule creating unit 12 obtains the unit price of the fuel cell from the unit price calculating unit 13 and compares the unit price of the fuel cell 1 with the unit price of the electricity bill when the electricity is purchased from the external power supply 50. Then, the operation schedule of the fuel cell 1 is determined. The unit price of the electricity rate for one day is acquired from the electricity rate system storage unit 14, and the day is divided into a plurality of time zones at the time when the unit price of the electricity rate is different. The unit price of the power generation of the fuel cell and the unit price of the electricity rate are compared for each of these time zones.

In a low electricity rate time zone in which the electricity rate is lower than the power generation rate of the fuel cell 1, a schedule is set so that the fuel cell 1 is stopped or operated at the first operation capacity.
When the low electricity rate time zone is short, it is desirable to keep the operation of the fuel cell 1 at the first operation capacity in order to smoothly shift to the operation mode of the fuel cell in the next time zone. Conversely, when the unit price of the electricity bill is equal to or higher than the power generation unit price of the fuel cell 1, the fuel cell 1 is scheduled to operate.

However, during a high electricity rate time zone in which the electricity rate is higher than the power generation rate of the fuel cell 1, the external power supply 50
Set a flag that does not purchase electricity more. Furthermore, in this time zone, scheduling is performed so as to minimize power purchase and to perform an operation following power consumption of the power load 20.
On the other hand, in an equivalent time zone in which the unit price of the power charge is equal to the unit price of the fuel cell, a flag is set to allow the purchase of power.

The actual unit price of power generation of the fuel cell varies depending on the operating efficiency of the fuel cell 1, and it is difficult to predict the operating efficiency in a time-series manner. It is desirable that the power generation unit price calculated by the power generation unit price calculation unit 13 has a certain range, and the power generation unit price is determined based on whether or not the unit price falls within this range. For example, in the case of a 1.5 kW class fuel cell, the fuel cell is 1 /
Assuming that the operation at 2 is used as a reference, the unit cost of power generation at the time of operation at the rated value is improved by about 10%, and the unit price of power generation at the time of operation at 1/4 of the rated value is reduced by about 10%.

Therefore, the operation schedule creation unit 12
For example, 1.1 is held as an upper limit constant and 0.9 is held as a lower limit constant for giving a range to the power generation unit price.
The fuel cell calculated by the unit price calculation unit 13 is 1/1 of the rating.
In the case of operation at 2, the unit price of electricity is higher than the value obtained by multiplying the unit price by the upper limit. A time zone that is less than the multiplied value and higher than the value obtained by multiplying the power generation unit price by the lower limit constant is an equivalent time zone, and a time zone in which the unit price of the electricity price is less than the value obtained by multiplying the generation unit price by the lower limit constant is the low electricity rate. It is realistic to determine the time zone. At present, in all electrified houses under the jurisdiction of Tokyo Electric Power Co.,
From 7:00 to the next morning, the equivalent time zone is from 7:00 to 10:00, and from 17:00 to 23:00, and the high electricity rate time zone is from 10:00 to 1
It corresponds to the time zone of 7:00.

Next, the operation schedule creating section 12 determines a schedule for charging the storage battery 4 in the equivalent time zone. In the high electricity rate time zone, the power consumption of the power load 20 becomes large during the operation of the air conditioner in summer or the like, and often exceeds the maximum power generation output when the fuel cell 1 is operated at the rated speed.
Therefore, the storage battery 4 is charged with a sufficient amount of electric power before entering the high electricity rate time zone. Charging of the storage battery 4 is performed during an equivalent time zone. This is because if the battery is charged in a low price time zone having a time lag from the high electricity rate time zone, the amount of stored power is spontaneously discharged, resulting in poor charging efficiency.

By charging the storage battery 4, even if the power consumption of the power load 20 exceeds the maximum power generation output of the fuel cell 1 during the high electricity rate period, the discharge of the storage battery 4 can cope with the increase in the power load. You don't have to buy expensive electricity.
In addition, when the power consumption of the power load 20 increases rapidly during the high electricity rate time zone, if the storage battery 4 is discharged, the power generation output shortage caused by poor time response of the fuel cell 1 during the power load following operation is compensated for. Power consumption can be eliminated.

As a method of charging the storage battery 4 in the equivalent time zone, for example, at the beginning of the equivalent time zone, scheduling is performed such that the fuel cell 1 is efficiently operated at rated operation until the storage battery 4 is fully charged. In the equivalent time zone, any schedule may be set as long as the storage battery 4 can be fully charged. However, in the time zone where the time response of the fuel cell itself is poor or power can be purchased from the external power supply 50, In view of this, it is desirable to operate at rated operation, constant power generation operation, or a combination thereof.

The operation schedule creating section 12 passes the schedule of the fuel cell 1 obtained as described above to the control section 11. The control unit 11 operates the fuel cell 1 according to a schedule. In the equivalent time zone, first, the fuel cell 1 is operated at the rated value, and the switch 31 is operated, and the surplus power generation output is stored in the storage battery 4.
To charge. In this time zone, if the power consumption of the power load 20 exceeds the rating or cannot keep up with the change in the power consumption, the switch 30 is operated and power is purchased from the external power supply 50 to take measures. In the high electricity rate period, when power consumption exceeding the rated power generation occurs, the switch 32 is operated to control the switch so as to supply the charge amount of the storage battery to the power load 20. Further, in the low electricity rate time zone, the fuel cell is stopped, and the power load is purchased from the outside with all the necessary electric energy, or the fuel cell has the minimum operating capacity (referred to as the first operating capacity during the hot summer in this specification). ). The minimum operating capacity is to operate at about 1/4 of the rated current fuel cell.

As described above, by adopting the configuration of the present embodiment, the unit price of the electricity rate when the power is purchased from the external power supply 50 is compared with the unit price of the power generation of the fuel cell 1, and 1 is determined according to the magnitude.
The day is divided into three time zones, the fuel cell is stopped or operated at the first operation capacity during the low electricity rate time zone, and the power generation output of the fuel cell is charged into the storage battery during the equivalent time zone, and the high electricity During the charge period, the operation schedule of the fuel cell is determined so as to perform the power load following operation while using the charge amount of the storage battery without purchasing power from the external power source, so reduce the total of the electricity rate and the fuel gas rate. A control device for a fuel cell system can be provided.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
FIG. 2 is a configuration diagram illustrating a configuration of a control device according to the embodiment. Reference numeral 16 denotes a power consumption storage unit that stores time-series data of the power consumption of the power load 20 measured by the power consumption measurement unit 3 for the previous day or for a predetermined period from the previous day. This predetermined period is desirably about one week. The other configuration is the same as that of the first embodiment, and the description is omitted.

Next, the operation of the embodiment will be described.

When determining the schedule for charging the storage battery 4 in the equivalent time zone, the operation schedule creation unit 12 sends the time series of the power consumption of the power load 20 from the power consumption storage unit 16 to the previous day or to a predetermined period in the past from the previous day. Get the data. When time series data of a plurality of days is obtained, an averaging process is performed. Next, from the past data, the time when the power consumption of the power load 20 exceeds the maximum power generation output of the fuel cell 1 in the high electricity rate time zone is examined, and the excess of the power consumption from the maximum power generation output is multiplied by the excess time width. The excess power consumption is calculated by integrating the values. This power consumption corresponds to the power that may be purchased from the external power supply 50.

In the equivalent time zone in which the power purchase possible flag is set, the excess power consumption is scheduled to be charged to the storage battery 4. This makes it possible to reduce waste of the charged amount as much as possible. As an operation method of the fuel cell 1 at the time of charging, for example, there is a method of efficiently performing the rated operation of the fuel cell 1 until the storage battery 4 is charged with an amount of power equal to the excess power consumption at the beginning of the equivalent time zone.

The control unit 11 includes an operation schedule creation unit 1
The fuel cell 1 is operated according to the operation schedule of the fuel cell 1 obtained from Step 2. The power consumption of the power load 20 obtained by the control unit 11 from the power consumption measurement unit 3 is stored in the power consumption storage unit 16.

As described above, by adopting the configuration of the present embodiment, it is possible to eliminate the waste of the charge amount of the storage battery 4 in the equivalent time zone and to obtain the same effect as that of the first embodiment.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
FIG. 2 is a configuration diagram illustrating a configuration of a control device according to the embodiment. Reference numeral 25 denotes a communication unit that receives the electricity rate system information transmitted by the external power supply 50. The communication unit 25 is, for example, a terminal adapter, is connected to the external power supply 50 by, for example, a digital dedicated line or a public line, and is connected to the control device 10 by a common interface. The electricity rate system information stores the unit price of the electricity rate for each time zone. The other configuration is the same as that of the first embodiment, and the description is omitted.

Next, the operation of this embodiment will be described.

When the external power source 50 transmits the electricity bill system information, the communication unit 25 receives the information and stores it in the electricity bill storage unit 14 in the control unit 10. When the contents of the electricity rate system storage unit 14 change, the operation schedule creation unit 12 uses this as a trigger to redetermine the operation schedule of the fuel cell 1 according to the new electricity system. For example, when it is predicted that the power supply of the external power supply 50 will be tight during the daytime in summer, the external power supply 50 sets the unit price of the daytime electricity rate high in the communication unit 25 or sets the time zone width during which the unit price of the electricity rate is high. Send the changed electricity bill, such as expansion. Then, the operation schedule creation unit 12 changes the time zone in which a flag indicating that power is not purchased is set based on the new electricity tariff system, or changes the time for storing power in the storage battery 4 and the amount of stored power.

As described above, with the configuration of the present embodiment, when the external power supply 50 changes the unit price of the electricity bill, the operation schedule of the fuel cell can be changed with high immediacy.

[0038]

As is apparent from the above description, the present invention relates to the case where the fuel cell and the external power supply are used together for power supply, and the unit price of the electricity charge when the power is purchased from the external power supply and the power generation of the fuel cell. Compare with the unit price, and depending on the size, 1
The day is divided into three time zones, the fuel cell is stopped during the low electricity rate time zone, the power output of the fuel cell is charged to the storage battery during the equivalent time zone, and the external power source is charged during the high electricity rate time zone. Since the operation schedule of the fuel cell is determined so that the power load following operation is performed while using the charge amount of the storage battery without performing power purchase, a control device of the fuel cell system that reduces the total of the electricity rate and the fuel gas rate is determined. Can be provided.

Further, by providing a communication unit with the external power supply, it becomes possible to change the operation schedule of the fuel cell with high immediacy when the external power supply changes the unit price of the electricity bill.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a control device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a control device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a configuration of a control device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of the technology described in Japanese Patent Application Laid-Open No. 6-325774.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Inverter 3 Power consumption measurement part 4 Storage battery 10 Controller 11 Control part 12 Operation schedule creation part 13 Unit price calculation unit 14 Electricity charge system storage unit 15 Fuel gas charge system storage unit 16 Power consumption storage unit 19 Timer Reference Signs List 20 power load 21 hot water supply load 25 communication unit 30 switch 31 switch 32 switch 50 external power supply

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H02J 7/34 H02J 7/34 J (72) Inventor Nagamitsu Sayo 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term (reference) in Matsushita Electric Industrial Co., Ltd. 5G003 AA05 BA01 DA07 GB06 5G066 AA02 CA08 DA08 HB07 HB09 JA07 JA12 JB03 KA12 5H027 AA02 BA01 DD03 DD06 KK52 MM26 MM27

Claims (5)

[Claims] 1. A fuel cell system for generating electric power and heat from fuel gas and air and supplying them to an electric power load and a heat load, respectively, comprising: a storage battery for accumulating a power generation output of the fuel cell; An operation schedule creation unit that determines the power generation output of the fuel cell and the charge or discharge of the storage battery according to the operation schedule. The time zone, that is, the high electricity rate time zone where the unit price of the electricity rate is higher than the unit price of the fuel cell, the equivalent time zone where the unit price of the electricity rate is the same as the unit price of the fuel cell, and the unit price of the electricity rate is the fuel cell In the high electricity rate time zone, the fuel cell generates the amount of power consumed by the power load. In the equivalent time period, the fuel cell charges the storage battery with the power that has not been consumed, and in the low electricity rate time period, creates an operation schedule such that the fuel cell is stopped or operated at the first operation capacity. A control device for a fuel cell system, comprising: 2. A fuel cell system for generating electric power and heat from fuel gas and air and supplying the electric power and heat to an electric load and a heat load, respectively, comprising: a storage battery for accumulating a power generation output of the fuel cell; A power consumption storage unit that stores information on a change in the amount of power to be performed; an operation schedule creation unit that determines a daily operation schedule; and a power generation output of the fuel cell and charging or discharging of the storage battery according to the operation schedule. The operation schedule creating unit includes a time zone of one day in three time zones, that is, a high electricity rate time zone in which the unit price of the electricity rate is higher than the unit price of the fuel cell, and the unit price of the electricity rate. Is divided into an equivalent time zone in which the unit price is the same as the fuel cell unit price, and a low electricity rate unit in which the unit price of the electricity fee is lower than the unit price of the fuel cell In the high electricity rate time zone, the fuel cell generates the amount of power consumed by the power load, and in the equivalent time zone, the fuel cell charges the storage battery. Is the power amount obtained by subtracting the maximum power generation amount of the fuel cell from the power consumption amount used during the subsequent high electricity rate time zone, where the charging start time is set so that the charged power amount is used immediately after the end of charging. A control device for a fuel cell system, wherein an operation schedule is created such that the fuel cell is stopped or operated at a first operation capacity in a low electricity rate time zone. 3. A fuel cell system comprising: a communication unit for receiving electricity rate system information from an external power source; wherein the operation schedule creation unit is configured to operate the fuel cell when the electricity rate storage unit acquires the information on the electricity rate system. 2. The method according to claim 1, wherein
Or a control device of the fuel cell control system according to 2. 4. The unit price of the electricity rate is higher than a value obtained by multiplying an electricity generation unit price of the fuel cell by an upper limit constant in the high electricity rate time zone. The value obtained by multiplying the power generation unit price of the fuel cell by the lower limit constant during the low electricity rate period is equal to or less than the value obtained by multiplying the upper limit constant and higher than the value obtained by multiplying the unit price of the fuel cell by the lower limit constant. The control device for a fuel cell system according to any one of claims 1 to 3, wherein: 5. The method according to claim 1, wherein the fuel cell is operated at a rated value only during a certain period of an equivalent time period, and a part of the electric energy used by the power load is charged in a high electricity rate time period after the equivalent time period. The control device for a fuel cell system according to claim 1, wherein: