JP2003229154A - Surplus power control system and control method, and power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To absorb the surplus power without lowering the efficiency of the system even if surplus power is generated due to the transient response of the fuel cell by the fluctuations of the AC load, in the power supply system having a fuel cell for supplying power to the AC load. <P>SOLUTION: A surplus power control system which comprises a power consumption equipment 5 and an equipment control device 10 is used. The power consumption equipment 5 is operated using the surplus power as a power excluding the load power used for the load 8 out of the fuel cell power that is generated by the fuel cell 2 for supply to the load 8. The equipment control device 10 controls the fuel supplied to the fuel cell 2 so as to increase the fuel cell power when the state of the power consumption equipment 5 satisfies a first condition established beforehand and, when the state of the power consumption equipment 5 satisfies a second condition established beforehand, controls the fuel cell power so as to supply a ratio established beforehand to the power consumption equipment 5 out of the fuel cell power. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surplus power control system for a fuel cell, a surplus power control method and a power supply system to which the surplus power control method is applied, and more particularly to controlling surplus power generated by a fuel cell. The present invention relates to a surplus power control system, a surplus power control method, and a power supply system to which they are applied.

[0002]

2. Description of the Related Art Fuel cells have been drawing attention for their effects of reducing environmental load such as low emission of harmful substances and high energy efficiency due to cogeneration. As a utilization form of the fuel cell, a power supply system is known in which the fuel cell is connected to an AC load in parallel with a system power source via an inverter. At that time, a hydrogen-rich reformed gas obtained by reforming an organic hydrocarbon-based material (eg, natural gas, propane gas, methanol) is known as a fuel for a fuel cell. The power supply system can be introduced to various facilities and homes.

FIG. 2 shows a graph of the time change of the electric power of the fuel cell supplied in the electric power supply system and the electric power of the consumed AC load. The vertical axis represents electric power and the horizontal axis represents time. Curve: AC load power conceptually shows the time change of the power (power consumption) used by the AC load. Also,
Curve: Fuel cell electric power shows the time change of the electric power generated by the fuel cell in response to the change of the AC load. When the AC load power sharply decreases, the fuel cell power does not decrease in time, and a surplus of power (area indicated by A) is generated. On the contrary, when the AC load power sharply increases, the fuel cell power does not increase in time, and a power shortage (region indicated by B) occurs. In the area B, the power shortage is supplied from the system power supply to the AC load. In the area A, the surplus power is either stored in the secondary battery or returned to the grid by reverse flow. The power of the secondary battery may be used when a power shortage occurs (region B, etc.).

A power supply system using a conventional fuel cell and secondary battery will be described in detail. FIG. 4 is a diagram showing a configuration of a power supply system using a conventional fuel cell. The power supply system includes a reformer 101, a fuel cell (FC) 102, a power conditioner 103, a reformer load amount control unit 104, a flow rate control valve 107, a converter current command calculation unit 106, a load power calculation unit 110, and charging. The container 114 and the secondary battery 120 are provided. The power conditioner 103 includes a DC / DC converter 111 and a DC / DC converter 111.
AC inverter 112, converter input current controller 11
3. An ammeter 116 is provided.

The power supply system is connected in parallel with the local load 108 together with the system power supply 109. And
Power is supplied to the premises load 108. A voltmeter 118 and an ammeter 11 are connected to the line that supplies power to the premises load 108.
9 are installed.

The respective components will be described below. The flow rate control valve 107 supplies the reformer _load signal R _load (0-100%) from the reformer load amount control unit 104 (described later) to the reformer 101 (described later) according to the opening degree of the valve. The amount of fuel F ₁ supplied is controlled. Here, the fuel F ₁ is a gas in which an organic hydrocarbon fuel gas and water vapor are mixed.

The reformer 101 uses the fuel F ₁ supplied from the flow control valve 107 to carry out a steam reforming reaction,
A desired reformed gas F ₂ (steam, gas containing hydrogen as a main component) is generated. The generated reformed gas F ₂ is used in the fuel cell 1
02 (described later).

The fuel cell (FC) 102 is supplied with
Quality gas F_TwoAnd a gas containing oxygen (such as air)
Then, electricity is generated by an electrochemical reaction (battery reaction). Departure
Electric power P_FC(Hereinafter "FC output power", its voltage
"FC output voltage V_FC, The current is "FC output current
I_FC") Is DC power. FC output power P
_FCIs output to the power conditioner 103.

The power conditioner 103 will be described. DC / DC converter 111 based on the FC output power _{P FC} (DC power) from the fuel cell 2, the DC power _{P CON} obtained by boosting the voltage (hereinafter "converter output power _{P CON",} the voltage "converter output Voltage V
_CON ", and its current is converted to" converter output current I _CON "
Is output to the DC / AC inverter 112.

In the converter input current control unit 113, the FC output current I _FC measured by the ammeter 116 is
FC output current command I _FC ^* (from converter current command calculation unit 106 (described later)) FC output current I _FC
To control.

The DC / AC inverter 112 is a DC / D
Converter output power P that is the output of the C converter 111
Based on the input of _CON (DC power), the converter output power P _CON is converted into AC power of a desired frequency and voltage (hereinafter, “inverter output power P _{IN V} ”, its voltage is “inverter output voltage V _INV ”, its current is "Inverter output current I _INV ") and output to the local load 108.

The secondary battery 120 is charged by a charger 114 with a power source having a predetermined voltage or higher, and is discharged to another element having a predetermined voltage or lower. Here, when the converter output voltage V _CON is equal to or higher than the set value, the secondary battery 120 is charged by the power conditioner 103. When the converter output voltage V _CON is less than another set value, the secondary battery 1
20 discharges to the power conditioner 103.

The load power calculation unit 110 includes a system power supply 109.
And AC load power P _DMD supplied from the power supply system to the premises load 108 (hereinafter, “AC load power P _DMD ”, its voltage is “AC load voltage V _DMD ”, and its current is “AC load current I _DMD ”). ) _{Is the} AC load current I _DMD measured by the ammeter 119 and the voltmeter 1
It is calculated based on the AC load voltage V _DMD measured at 18.

The reformer load amount control unit 104 controls the load power.
AC load power P from the calculation unit 110 _DMDOn the basis of,
Operating conditions of the reformer 101 (load amount: provided to the reformer 101
Fuel F to be supplied (reformed)₁Flow rate). So
And its flow rate F₁₁Based on the flow rate control valve 107
But its flow rate F₁₁The reformer load signal
R_loadTo calculate. Reformer load signal R
_loadIs the flow control valve 107 and FC output current command
Output to the calculation unit 116.

The converter current command calculation unit 106 calculates the FC current target value as the target value of the FC output current I _FC based on the input of the reformer load signal R _load , and F
Power conditioner 1 as C output current command I _FC ^*
Output to 03.

Next, the operation of the power supply system using the conventional fuel cell will be described. The flow rate F ₁₁ of the fuel F ₁ used in the reformer 101 is controlled by the flow rate control valve 107 by the reformer load signal R _load.
01 is supplied. Then, the fuel F ₁ becomes the reformed gas F ₂ by the steam reforming reaction. Its flow rate is F ₂₁ . The fuel cell 102 uses the supplied reformed gas F ₂ and air to generate electricity by an electrochemical reaction (cell reaction). The generated FC output power P _FC is output to the power conditioner 103.

The power conditioner 103 converts the FC output power P _FC into inverter output power P _INV having a desired voltage and frequency and outputs it to the local load 108. At that time, by the converter input current control unit 113,
It controls the FC output current I _FC . Load power calculation unit 110
Calculates the AC load power P _DMD supplied from the system power supply 109 and the power supply system to the local load 108.
The amount of electric power generated by the fuel cell 2 is controlled based on this value. The AC load power P _DMD is output to the reformer load amount control unit 104.

The load calculation unit 131 of the reformer loading amount control unit 104, based on the AC load power _{P DMD,} necessary to output the AC load power _{P DMD,} reformer 10
The flow rate F ₁₁ of the fuel F ₁ required for 1 is obtained. And F
_The signal indicating the valve opening of the flow control valve 107 corresponding to ₁₁ is used as the reformer load signal R _load , and the flow control valve 10
7 and the converter current command calculation unit 106.

The converter current command calculation unit 106 includes a reformer
Load signal R_loadBased on the input of
Flow I_FCFC output current command I as the target value of_FC ^*The
Output to the word conditioner 103. Flow control valve 10
7 is the reformer load from the reformer load amount control unit 105
Signal R _loadBased on the valve opening degree, the reformer 10
Fuel F to supply 1₁Supply F₁₁To control.

In the above operation, t1 to t3 shown in FIG.
Think about the time situation. In this case, the AC load power P
_{Since the DMD} has decreased sharply, the response of the power supply system is not in time and the power shown in the area A becomes excessive. In that case, the value of the converter output voltage V _CON becomes equal to or higher than the set value, so that the surplus electric power at this time is charged in the secondary battery 120.

In the above operation, t3 shown in FIG.
Consider the situation at a later time. In this case, the AC load power P
_Due to the rapid increase in _DMD, the response of the power supply system is not in time, and the power shown in the B area becomes insufficient. At this time, power is supplied from the secondary battery 120 to the converter, and at the same time, power is supplied from the system power supply 109.

As described above, in the prior art shown in FIG. 4, by installing the secondary battery 120, the surplus power due to the delay in the reaction of the power supply system (due to the responsiveness of the reformer in the fuel cell) is appropriately set. It can be stored in and used effectively.

However, when the secondary battery 120 is used, the secondary battery capacity is the maximum FC output power P _FCmax generated by the fuel cell 102 when the reformer 101 is operated with the maximum reformer load amount. From the state that is outputting
The minimum FC output power P _FCm generated by the fuel cell 102 when the reformer 101 is operated with the minimum reformer load amount.
_It is necessary to have a capacity enough to absorb the amount of electric power output when the state of outputting in is shifted by the delay time of the response of the reformer 101. That is, a large-capacity secondary battery 120 is required, an installation place must be secured, and equipment costs are required. Further, during charging / discharging of the secondary battery 120, part of the electric power is lost due to internal resistance loss of the secondary battery 120 or the like. That is, the efficiency of the power supply system may decrease. In addition, the secondary battery 120
Deteriorates due to various factors. Therefore, it is necessary to regularly inspect and replace, and maintenance costs are required.

In a power supply system having a fuel cell, there is a demand for a system capable of absorbing excess power without lowering system efficiency. Even when a secondary battery is connected, there is a demand for a system capable of suppressing the capacity and absorbing excess power. There is a need for a system that absorbs excess power that does not deteriorate and does not need replacement. There is a need for a system that absorbs excess power that can be realized at low cost.

[0025]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a surplus power control system and surplus power control capable of absorbing surplus power without lowering the system efficiency of a power supply system having a fuel cell. A method and a power supply system.

Another object of the present invention is to provide a surplus power control system, a surplus power control method and a power supply system capable of suppressing the capacity of a secondary battery of a power supply system having a fuel cell as much as possible. That is.

Another object of the present invention is to provide a surplus power control system, a surplus power control method and a power supply system in which the equipment of the power supply system having a fuel cell is less deteriorated and does not need to be replaced.

Another object of the present invention is to provide a surplus power control system, a surplus power control method and a power supply system having a fuel cell which can be realized at low cost.

[0029]

[Means for Solving the Problems] Means for solving the problems will be described below by using the numbers and symbols used in the embodiments of the present invention. These numbers and signs are added to clarify the correspondence between the description of [Claims] and the [Embodiment of the Invention]. However, those numbers and signs should not be used for the interpretation of the technical scope of the invention described in [Claims].

Therefore, in order to solve the above problems, the surplus power control system of the present invention comprises a power consumption facility (5),
An equipment control device (10) is provided. The power consuming facility (5) is the power of the fuel cell (2) supplied to the load (8) generated by the fuel cell (2) excluding the load power used by the load (8). It is operated using the surplus power of. The equipment control device (10) controls the fuel supplied to the fuel cell (2) so as to increase the fuel cell power when the state of the power consumption equipment (5) satisfies the preset first condition. .

The surplus power control system of the present invention is
When the state of the power consumption facility (5) further satisfies the preset second condition, the facility control device (10) transfers a preset ratio of the fuel cell power to the power consumption facility (5). Control the fuel cell power to supply.

The surplus power control system of the present invention is
The electric power consumption facility (5) uses the surplus power to heat water, a heater (31), a hot water storage tank (32) capable of storing the heated water, and a hot water storage tank (32) inside the hot water storage tank (32). Sensor that can measure the hot water level as the water level of heated water (3
3) and are provided.

Further, in the surplus power control system according to the present invention, the first condition is that the hot water level of the hot water is equal to or lower than the preset first reference water level, and the equipment control device (10) uses the sensor ( Based on the output of 33), it is determined whether the first condition is satisfied.

Further, in the surplus power control system of the present invention, the second condition is that the hot water level of the hot water is equal to or lower than the preset second reference water level, and the equipment control device (10) uses the sensor ( Based on the output of 33), it is determined whether the second condition is satisfied.

In order to solve the above-mentioned problems, a power supply system of the present invention comprises a fuel supply device (7), a fuel cell (2), a power converter (3), and a surplus power control system (5, 10). ) And a control unit (4). The fuel supply device (7) controls the supply of the fuel to the fuel cell (2). The fuel cell (2) uses its fuel and gas containing oxygen to generate its fuel cell power. The power converter (3) converts the fuel cell power so that it can be supplied to the load (8) and outputs it as the load power to the load (8). The surplus power control system (5, 10) is described in any one of the above items. The control unit (4) calculates a fuel supply amount as a supply amount of fuel to be supplied to the fuel cell (2) based on the load power, and controls the fuel supply device (7) based on the fuel supply amount. Outputs a control signal for controlling. Here, the power converter (3) outputs the surplus power to the power consumption facility (5). Equipment control device (10)
Controls the fuel by changing its control signal based on the state of the power consuming facility (5).

In the power supply system of the present invention, the water is used independently of the fuel cell (2).

The surplus power control method of the present invention for solving the above-mentioned problem is the load (8) of the fuel cell power as the power generated by the fuel cell (2) supplied to the load (8). Using the surplus power as the power excluding the load power as the power to be used, the step of heating the water, the step of storing the heated water in the storable hot water storage tank (32), and the heated When the water level in the hot water storage tank (32) becomes equal to or lower than the preset first reference water level, the step of increasing the surplus power is provided.

In the surplus power control method of the present invention, the load as the power used by the load (8) among the fuel cell power as the power generated by the fuel cell (2) supplied to the load (8) is used. Using surplus power as power excluding power,
The step of heating water, the step of storing the heated water in a hot water storage tank (32) capable of storing the water, and the water level in the hot water storage tank (32) of the heated water are preset second reference water levels. And if all of the fuel cell electric power is used as the surplus electric power,

A program relating to the present invention for solving the above-mentioned problem is to use the electric power used by the load (8) among the electric power of the fuel cell as the electric power generated by the fuel cell (2) supplied to the load (8). And supplying the surplus power as power excluding the load power to the power consumption facility (5) for heating water and storing it in the hot water storage tank (32), and the heated water hot water storage tank (32) Increasing the fuel cell power to the computer when the water level at the water level becomes equal to or lower than the preset first reference water level.

Further, the program according to the present invention excludes the load power as the power used by the load (8) from the fuel cell power as the power generated by the fuel cell (2) supplied to the load (8). And a step of supplying surplus power as electric power to the power consumption facility (5) for heating water and storing it in the hot water storage tank (32), and the heated water hot water storage tank (3).
When the water level in 2) becomes equal to or lower than the preset second reference water level, the step of supplying all of the fuel cell power to the power consuming facility (5) is executed by the computer.

The fuel supply amount control method and the computer program can change the order of steps within a range in which no contradiction occurs.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a surplus power control system, a surplus power control method, and a power supply system according to the present invention will be described below with reference to the accompanying drawings. Figure 1
FIG. 1 is a diagram showing a configuration in an embodiment of a power supply system to which a surplus power control system according to the present invention is applied.

The power supply system includes a reformer 1, a fuel cell (FC) 2, a power conditioner 3, a reformer load amount control unit 4, a hot water storage system 5, a converter current command calculation unit 6, a flow control valve 7, A hot water storage control system 10 and a load power calculation unit 20 are provided. The power conditioner 3
DC / DC converter 11, DC / AC inverter 1
2, converter input current controller 13, heater controller 1
4, a heater switch 15, an ammeter 16 and a voltmeter 17 are provided. Further, the hot water storage control system 10 includes the output changing unit 2
1 and a hot water storage level calculation unit 22. The hot water storage system 5 includes an electric heater 31, a hot water storage tank 32, and a temperature sensor 33.

The power supply system, together with the system power supply 9,
The power supply system is connected in parallel to a premises load 8 as a premises load of a building in which the power supply system is installed. Then, power is supplied to the local load 8. In order to calculate the magnitude of the power supplied from the system power supply 9, the line of the system power supply 9
A voltmeter 18 and an ammeter 19 are installed.

In the surplus power control system and the power supply system according to the present invention, the hot water storage system 5 is provided as a facility for effectively utilizing the surplus power. The hot water storage system 5 heats water using surplus power and supplies the water to a hot water supply system, an air conditioning system, or the like. That is, it is possible to effectively use the surplus power. In addition, when the output of the fuel cell 2 is small or when the level of the hot water storage tank of the hot water storage system 5 is lowered (insufficient hot water), not only the surplus power but also the output of the fuel cell 2 is actively heated. Used for. By doing so, the electric power of the fuel cell 2 including the surplus electric power can be effectively used, and the electric power can be stably supplied to the hot water storage system 5.

Each structure will be described below. The flow rate control valve 7 as a fuel supply device is used for the hot water storage control system 10
Reformer load signal R _load from (described below) (example: 0
-100%), the supply amount of the fuel F ₁ supplied to the reformer 1 (described later) is controlled by the opening degree of the valve. Here, the fuel F ₁ is a gas in which an organic hydrocarbon fuel gas and water vapor are mixed. It has a preset steam / carbon ratio. Examples of the organic hydrocarbon fuel gas include natural gas (methane), propane gas, and methanol.
A flow rate control valve (not shown) for the oxidant gas (gas containing oxygen) supplied to the fuel cell 2 is controlled in conjunction with the flow rate control valve 7.

However, the fuel gas and the water vapor may be controlled separately. In that case, the fuel gas flow control valve 7 '
And a steam flow control valve 7 ″ are prepared respectively. Then, based on the reformer load signal R _load , the supply amount of the fuel gas and the steam supplied to the reformer 1 is controlled by the opening degree of the valve. Each valve is adjusted in advance so that the water vapor / carbon ratio is preset. The steam / carbon ratio can be adjusted near the reformer 1, and more accurate control is possible.

The reformer 1 uses the fuel F ₁ supplied from the flow rate control valve 7 to carry out a steam reforming reaction to generate a desired reformed gas F ₂ (gas mainly composed of steam and hydrogen). To generate. Control of the hydrogen content in the reformed gas F ₂ is able to perform operating pressure and temperature, the supply amount of the fuel F _1, by controlling the composition of the fuel F _1. In this embodiment,
It is controlled by the supply amount of the fuel F ₁ .

Further, by introducing a little oxygen into the reformer 1,
It is also possible to obtain a gas containing steam and hydrogen as main components by the partial oxidation reaction. The generated reformed gas F ₂ is supplied to the fuel cell 2 (described later). In this case, since an exothermic reaction occurs, it is not necessary to heat the reformer 1.

The fuel cell (FC) 2 supplies the supplied reformed gas F ₂ to the anode side (not shown) and the gas containing oxygen (air etc.) to the cathode side (not shown). ,
Electricity is generated by an electrochemical reaction (battery reaction) with an electrolyte. FC output power P _FC is DC power. The fuel cell is exemplified by a solid polymer type, a phosphoric acid type, a molten carbonate type, and a solid electrolyte type. The FC output power P _FC is output to the power conditioner 3. The fuel cell 2 may include the reformer 1. For example, an internal reforming type fuel cell.

The power conditioner 3 as a power converter outputs the inverter output power P _INV based on the FC output power P _FC . The respective parts will be described below. The DC / DC converter 11 is based on the input of FC output power P _FC (DC power) from the fuel cell 2.
Convert converter output power P _CON (DC power) to DC / A
Output to the C inverter 12. However, the converter output voltage V _CON (DC voltage) boosts the FC output voltage V _FC (DC voltage). Further, the FC output current I _FC output from the converter input current control unit 13 (ammeter 1
6) and the FC output current command I _FC ^* (from the converter current command calculation unit 6), the DC / DC converter 11 sets the FC output current I FC so as to eliminate the difference.
Control _FC .

The DC / AC inverter 12 is a DC / DC
Converter output power P, which is the output of the converter 11.
Based on input _CON (DC power) into a converter output power _{P C ON} to desired frequency and voltage of the inverter output power _{P INV,} and outputs to the premises load 8. Also,
When a control signal for setting the inverter output current I _INV to zero from the hot water storage control system 10 (described later) is input, the inverter output current I _{INV is set} to zero. That is, the DC / AC inverter 12 is stopped and the power supply to the premises load 8 is stopped.

The heater controller 14 detects the generation of surplus power based on the value of the converter output voltage V _CON measured by the voltmeter 17. When it is detected, the heater switch 15 is turned on so that the surplus electric power can be released to the hot water storage system 5. When the surplus power is exhausted, the heater switch 15 is turned off.

Here, the detection of surplus power will be described.
It FIG. 3 shows detection of excess power and O of the heater switch 15.
The relationship with N / OFF is shown. Horizontal axis is voltage V_BUS
(= Converter output voltage V_CON), Vertical axis is ON / OF
The state of F is shown. In FIG. 3, the heater control unit 14
Voltage V_BUS(= Converter output voltage V _CON) Is low
First reference voltage V preset from the_HHReached
In this case, it is determined that surplus power is generated (corresponding to the area A in FIG. 2).
Then, the heater switch 15 is turned on. Heater switch
When 15 is turned on, the converter output power P_CON
Surplus electric power flows to the hot water storage system 5 and is consumed (excess
Electric power is recovered as heat energy), voltage V_BUSBut
Go down. As a result, the voltage V_BUSBut the first reference voltage
Pressure V_HHThe second reference voltage V preset from_H(<First
Reference voltage V_HH) To reach. The heater control unit 14
At that time, the heater switch 15 is turned off. Comba
Data output power P_CONAre all DC / AC inverters again
Will be supplied to the computer 12.

Here, the first reference voltage V_HH= Second reference power
Pressure V_HThen, ON / OFF of the heater switch 15
It will be repeated in a short time. Therefore, it
The first standard so that the operation is performed smoothly and
Voltage V_HH＞ Second reference voltage V _H, And.

The hot water storage system 5 belongs to the surplus power control system. Upon receiving the supply of water, the water is heated by an electric heater 31 as a heater to generate hot water. The heating may be performed by another method as long as electric power is used. Hot water is stored in the hot water storage tank 32 inside. This hot water can be used for various facilities used for cogeneration such as a hot water supply system and an air conditioning system. When storing hot water inside, a temperature sensor 33 as a sensor is installed at a predetermined position of the hot water storage tank 32. The measured value is output to the hot water storage level calculation unit 22 of the reformer load control unit 4. The temperature sensors 33 may be installed at a plurality of locations in the hot water storage tank 32. It is also possible to install a liquid level gauge as a sensor.

The load power calculation unit 20 supplies the AC load power P _DMD (hereinafter “AC load power P _DMD ”, whose voltage is “AC load voltage V _DMD ”) to the premises load 8 from the system power supply 9 and the power supply system. , The current is referred to as “AC load current I _DMD ”) based on the AC load current I _DMD measured by the ammeter 19 and the AC load voltage V _DMD measured by the voltmeter 18.

Reformer load amount control unit 4 as a control unit
Is the AC load power P from the load power calculator 20._DMDof
The reformer load signal R is sent to the flow control valve 7 based on the input.
_loadIs output. That is, the fuel cell 2 is
Load power P_DMDOf the reformer 1 required to generate electricity
Case (load: fuel supplied (reformed) to reformer 1)
F ₁Flow rate F₁₁) Is calculated. And the flow rate F
₁₁On the basis of the flow rate control valve 7,₁₁Flow
So that the reformer load signal R_loadTo calculate.
Reformer load signal R_loadIs the hot water storage control system 10
Is output to. AC load power P required for flow rate calculation
_DMDAnd fuel F₁Flow rate F₁₁Data showing the relationship with
Can be grasped and
It is stored in the mass flow controller 4 and
used.

The hot water storage control system 10 belongs to the surplus power control system. When the amount of hot water stored in the hot water storage system 5 is small, a control signal is output to the power conditioner 3 so as to increase power supply, and the reformer load signal R _load is changed and output to the flow control valve 7 in order to increase hot water generation. To do. The hot water storage level calculation unit 22 uses the temperature sensor 3 of the hot water storage system 5.
The hot water storage level (water level) of the hot water storage tank 32 is estimated based on the temperature measurement value output from the unit 3.

At this time, if the hot water storage level is equal to or lower than the preset first reference water level S _L (first condition) (the amount of hot water storage is small), the reformer load signal R _{load is} sent to the output changing unit 21.
To output 100%. Thereby, F
The C output power P _FC can be greater than the AC load power P _DMD . That is, surplus power can be generated. As a result, surplus power is supplied to the hot water storage system 5, and the amount of hot water stored in the hot water storage tank 32 increases. Further, when the hot water storage level is equal to or lower than the preset second reference water level S _LL (second condition) (the amount of hot water storage is small), the output changing unit 21
To the DC / AC inverter 12 while outputting a signal for changing the reformer load signal R _load to 100%.
A control signal for making the inverter output current I _INV zero is output. Thereby, DC / AC inverter 12 can be stopped, and it becomes possible to supply all converter output power P _CON to hot water storage system 5. As a result, surplus power is supplied to the hot water storage system 5, and the hot water storage tank 3
The hot water storage amount of 2 increases. In addition, when the hot water storage level is equal to or lower than the second reference water level S _LL (second condition), the inverter output current I _INV is not zero, but a preset ratio (example:
It is also possible to use 5% of the total fuel cell power). The ratio is stored in the hot water storage control system 10. The above control when the amount of stored hot water is small ends when the stored hot water level reaches the preset third reference water level S ₀ .

The output changing section 21 includes a hot water storage level calculating section 22.
Based on the input signals changing the reformer load signal R _load from 100%, the opening degree of the reformer to load signals R _load, the valve of the flow control valve 7 from the reformer loading amount control section 4 Is changed to 100%, and is output to the flow rate control valve 7 and the converter current command calculation unit 6 as the reformer load signal R _load . However, when the above-mentioned control when the amount of stored hot water is small is not performed, the reformer load signal R _load from the reformer load amount control unit 4 is directly used as it is for the flow rate control valve 7 and the converter current command calculation unit 6. Output to.

[0062] converter current command calculation portion as a power command unit 6, based on the input of the reformer load signal _{R lo ad,} calculates the FC current target value as a target value of the FC output current _{I FC,} the FC output The current command I _FC ^* is output to the power conditioner 3. The output timing is predicted in advance by the responsiveness of the reformer ₁ (change in the hydrogen amount of the reformed gas F ₂ at the outlet of the reformer 1 with respect to the change in the fuel F ₁ supply amount), and is adjusted to that. In this embodiment, a dead time response and a temporary delay response are assumed as the responsiveness, and control is performed using their respective transfer functions.

Next, the operation of the surplus power control system, surplus power control method and power supply system according to the present invention will be described.

The flow control valve 7 has a reformer load signal R
Fuel F is controlled by controlling the opening based on _load.
The supply amount of ₁ is controlled and supplied to the reformer 1. Reformer 1
Uses the fuel F ₁ supplied from the flow control valve 7 to perform a steam reforming reaction to generate a desired reformed gas F ₂ . Then, the reformed gas F ₂ is output to the fuel cell 2. The fuel cell 2 supplies the supplied reformed gas F ₂ to the anode side, supplies a gas containing oxygen to the cathode side, and generates electricity by an electrochemical reaction (cell reaction) in the electrolyte. The generated FC output power P _FC is the power conditioner 3
Is output to.

In the power conditioner 3, DC /
The DC converter 11 outputs FC output power from the fuel cell 2.
P_FCConverter output power P based on the input of_CON
Is output to the DC / AC inverter 12. In addition,
I from the burner input current control unit 13_FCBased on control signal
And FC output current I_FCFC output current command I_FC ^*
Control to become.

The heater controller 14 monitors the value of the converter output voltage V _{CON with} the voltmeter 17. Then, when the converter output voltage V _CON reaches the preset first reference voltage V _HH , it is determined that excess power has been generated, and the heater switch 15 is turned on. The surplus electric power is supplied to the hot water storage system 5 and used for hot water storage. And
When the converter output voltage V _CON reaches the preset second reference voltage V _H, it is determined that there is no excess power, and the heater switch 15 is turned off. All the converter output power P _CON is again supplied to the DC / AC inverter 12.

The hot water storage system 5 generates hot water by generating excess power and uses it for various facilities used for cogeneration such as a hot water supply system and an air conditioning system. The hot water storage level is measured by the temperature sensor 33.
The output from the hot water storage control system 10 is monitoring. Then, when the hot water storage level is smaller than the preset first reference water level S _L (the amount of hot water storage is small), the hot water storage control system 10 increases the hot water generation in order to increase the hot water production.
Output is increased to generate more surplus power. That is, the flow rate of the reformed gas F ₂ supplied to the fuel cell 2 is increased. Therefore, the reformer load amount control unit 4 forcibly changes the reformer load signal R _load determined based on the input of the AC load power P _DMD from the load power calculation unit 20 to 100%. That is, the hot water storage control system 10 sends the reformer load signal R to the output changing unit 21.
A signal for changing _load to 100% is output. Output changing unit 21, and outputs the modified reformer load signal _{R lo ad} 100% to the flow control valve 7. Since the fuel flow rate increases, the FC output power P _FC can be greater than the required AC load power P _DMD . That is, surplus power can be generated. As a result, surplus power is supplied to the hot water storage system 5, and the hot water storage level rises.

When the hot water storage level is smaller than the preset second reference water level S _LL (the amount of hot water storage is very small), the hot water storage control system 10 changes the output change unit 21 to rapidly increase the generation of hot water. Pawn load signal R _load is 1
A signal for changing to 00% is output, and a control signal for setting the inverter output current I _INV to zero is output to the DC / AC inverter 12. Thereby, the DC / AC inverter 12 can be stopped and the converter output power P
It becomes possible to supply all the _CON to the hot water storage system 5. As a result, surplus power is supplied to the hot water storage system 5, and the amount of hot water stored in the hot water storage tank 32 increases.

The DC / AC inverter 12 is a DC / DC
Converter output power P, which is the output of the converter 11.
Based on the input of _CON , converter output power P _CON
The inverter output power P _INV of the desired frequency and voltage
And outputs to the local load 8. When the supply stop signal from hot water storage control system 10 is input, the power supply to premises load 8 is stopped based on the signal.

Each of the above components (reformer 1, fuel cell 2, power conditioner 3, reformer load amount control unit 4, hot water storage system 5, converter current command calculation unit 6, flow control valve 7, hot water storage control system 10) The operation of the load power calculation unit 20) is performed by a control unit (not shown) that controls the entire operation, or
This can be performed by a control unit (not shown) provided for each of several configurations.

The surplus power is effectively used as heat energy by the electric heater. And it is always used.
Therefore, it is possible to absorb the surplus power without reducing the system efficiency of the power supply system having the fuel cell.

Further, this hot water storage system can constitute a system independent of other circulating water (cooling water or heat medium for heat exchange) used as a utility of the power supply system. Therefore, there is no fear that foreign matter, impurities, etc. will enter from the utility equipment, the fuel cell, etc. That is, it is possible to supply hot water that does not have a sanitary problem.

Since a large capacity secondary battery is not used at all, it is not necessary to consider deterioration or replacement of the secondary battery. Therefore, normal maintenance is very easy. It is possible to significantly reduce the maintenance labor and the cost of replacing the secondary battery.

It is also possible to connect secondary batteries in parallel to the hot water storage system. For example, a switch is installed in each of the hot water storage system and the secondary battery. Then, normally, when excess power is generated, the switch on the hot water storage system side is turned on.
Set to N and absorb excess power in the hot water storage system. If the hot water tank is full, turn on the switch on the secondary battery side,
The secondary battery absorbs excess power. This may be reversed. This makes it possible to flexibly use (store) the surplus power. Then, the capacity of the secondary battery can be suppressed as much as possible.

[0075]

According to the present invention, in a power supply system having a fuel cell for supplying electric power to an AC load,
Even if surplus power is generated due to the transient response of the fuel cell due to the fluctuation of the AC load, it is possible to absorb the surplus power without reducing the efficiency of the system.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration in an embodiment of a surplus power control system, a surplus power control method, and a power supply system according to the present invention.

FIG. 2 is a graph showing a change with time in the electric power of the fuel cell supplied in the electric power supply system and the electric power of the consumed AC load.

[Fig. 3] Converter output voltage and heater switch ON / OFF
It is a graph which shows the relationship with OFF.

FIG. 4 is a diagram showing a configuration of a power supply system using a conventional fuel cell.

[Explanation of symbols]

1 reformer 2 Fuel cell 3 power conditioners 4 Reformer load amount control unit 5 Hot water storage system 6 Converter current command calculator 7 Flow control valve 8 premises load 9 power supply 10 Hot water storage control system 11 DC / DC converter 12 DC / AC inverter 13 Converter input current controller 14 Heater controller 15 heater switch 16 ammeter 17 Voltmeter 18 Voltmeter 19 ammeter 20 Load power calculator 21 Output change section 22 Hot water storage level calculator 31 Electric heater 32 hot water storage tank 33 Temperature sensor 101 reformer 102 fuel cell 103 Power conditioner 104 reformer load amount control unit 106 converter current command calculator 107 Flow control valve 108 premises load 109 system power supply 110 Load power calculator 111 DC / DC converter 112 DC / AC inverter 113 converter input current controller 114 charger 116 ammeter 118 Voltmeter 119 ammeter 120 secondary battery

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H026 AA03 AA04 AA05 AA06                 5H027 AA03 AA04 AA05 AA06 BA01                       CC06 DD01 DD03 DD06 KK00                       KK51 MM01 MM12 MM26

Claims (11)

[Claims] 1. A power consumption that is operated by using surplus electric power as electric power excluding load electric power as electric power used by the load, of electric power of the fuel cell as electric power generated by a fuel cell supplied to a load. A facility, and a facility control device that controls fuel supplied to the fuel cell so as to increase the fuel cell power when the state of the power consumption facility satisfies a preset first condition, Surplus power control system. 2. The equipment control device further supplies a preset ratio of the fuel cell power to the power consumption equipment when the state of the power consumption equipment satisfies a preset second condition. The surplus power control system according to claim 1, wherein the fuel cell power is controlled so as to do so. 3. The electric power consumption facility uses a heater for heating water by using the surplus power, a hot water storage tank capable of storing the heated water, and the heated water in the hot water storage tank. The surplus power control system according to claim 1 or 2, further comprising: a sensor capable of measuring a stored hot water level as a water level. 4. The first condition is that the hot water storage level is equal to or lower than a preset first reference water level, and the facility control device determines that the first condition is based on an output of the sensor. The surplus power control system according to claim 3, which determines whether or not the power is satisfied. 5. The second condition is that the hot water level is equal to or lower than a preset second reference water level, and the facility control device determines that the second condition is based on the output of the sensor. The surplus power control system according to claim 3, which determines whether or not the power is satisfied. 6. The fuel supply device for controlling the supply of the fuel to the fuel cell, the fuel cell for generating the fuel cell power using the fuel and a gas containing oxygen, and the fuel cell power. A power converter that converts the power so that it can be supplied to the load, and outputs the load power to the load, the surplus power control system according to any one of claims 1 to 5, and the excess power control system based on the load power. A fuel supply amount as a fuel supply amount to be supplied to the fuel cell, and based on the fuel supply amount, a control unit which outputs a control signal for controlling the fuel supply device, The power converter outputs the surplus power to the power consumption equipment, the equipment control device changes the control signal based on the state of the power consumption equipment, controls the fuel, a power supply system . 7. The power supply system according to claim 6, wherein the water is used independently of the fuel cell. 8. The water is heated by using surplus electric power, which is electric power generated by the fuel cell supplied to the load, excluding load electric power used by the load. A step of storing the heated water in a hot water storage tank capable of storing the heated water, and a water level in the heated water hot water storage tank is equal to or lower than a preset first reference water level A surplus power control method comprising: an increasing step. 9. Water is heated by using surplus electric power as electric power excluding load electric power as electric power used by the load among electric power of the fuel cell as electric power generated by the fuel cell supplied to the load. A step of storing the heated water in a hot water storage tank capable of storing the heated water; and a step of storing the heated water in the hot water storage tank below a preset second reference water level. And making all of the excess power into the excess power, the excess power control method. 10. A surplus electric power, which is electric power generated by a fuel cell supplied to a load and excluding a load electric power used by the load, is stored by heating water. Supplying to a power consumption facility to store in the tank, the water level of the heated water in the hot water storage tank is below a preset first reference water level, increasing the fuel cell power, A program for causing a computer to execute the method comprising. 11. The water is heated by using surplus electric power as electric power excluding load electric power as electric power used by the load among electric power of the fuel cell as electric power generated by the fuel cell supplied to the load. And supplying the heated water to the power consumption facility to store the electric power in the hot water storage tank, when the water level of the heated water in the hot water storage tank is equal to or lower than a preset second reference water level, all of the fuel cell power is A program for causing a computer to execute the method including the step of supplying to a power consumption facility.