Patent Publication Number: US-2005136311-A1

Title: Power generation control system, power generation control method, program, and medium

Description:
TECHNICAL FIELD  
      The present invention relates to a power generation control system, a power generation control method, a program and a medium for supply of power to, for example, a domestic power load using a fuel cell, etc.  
     BACKGROUND ART  
      (A)  FIG. 11  shows a configuration of a conventional fuel cell power generation device (conventional technology  1 ) disclosed in Japanese Patent Laid-Open No. 7-57753. In  FIG. 11 , a fuel cell body  31  generates DC power by reaction between hydrogen supplied by hydrogen supply means  32  and oxygen in the air supplied by air supply means  33 , and a power converter  34  outputs AC power after converting the DC power into the AC power. At an external load command, a power control unit  35  controls a flow rate control unit  36  and the power converter  34 , the flow rate control unit  36  controls the flow rate of the hydrogen supply by the hydrogen supply means  32  and the flow rate of the air supply by the air supply means  33  such that the flow rates can be the optimum values, and the power converter  34  controls the amount of electricity output by the fuel cell body  31 , thereby successfully controlling the output power. An excess power prevention means  39  including a power detector  37  and an arithmetic unit  38  is provided between the fuel cell body  31  and the power converter  34  so that the amount of electricity can be appropriately suppressed when there is a steep rise in electricity output.  
       FIG. 12  shows the configuration of the fuel cell power generation device (conventional technology  2 ) disclosed in Japanese Patent Laid-Open No. 6-325774. In  FIG. 12 , a fuel cell body  41  generates DC power by reaction between hydrogen supplied by hydrogen supply means  42  and oxygen in the air supplied by air supply means  43 , and a power converter  44  outputs AC power after converting the DC power into the AC power. A control device  45  controls a charge/discharge device  46  and the power converter  44 , and can control the power output depending on an external load by the discharge from the charge/discharge device  46  or the charge to the charge/discharge device  46  although the amount of electricity from the fuel cell body  41  is constant. In the fuel cell power generation device, since the amount of electricity from the fuel cell body  41  is constant when the power output is controlled depending on a fluctuating external load, the amount of charge or discharge of the charge/discharge device  46  becomes considerably large. Therefore, a large capacity charge/discharge device  46  is required, and the entire device is costly and needs a large installation space.  
      (B) The configuration of the conventional fuel cell power generation system (conventional technology  3 ) disclosed in Japanese Patent Laid-Open No. 5-182675 and others is described below by referring to  FIG. 13  showing the configuration of the conventional fuel cell power generation system (conventional technology  3 ).  
      In  FIG. 13 , a fuel cell (body)  131  is connected to a load  134  through a battery  132  and an output control means  133  including an inverter.  
      The operations of the conventional fuel cell power generation system (conventional technology  3 ) are described below by referring to  FIG. 14  which is a graph for explanation of an example of an operation pattern of the conventional fuel cell power generation system (conventional technology  3 ).  
      In  FIG. 14 , the horizontal and vertical axes respectively indicate the time and power, and reference numerals  141  and  142  respectively denote a load power and output power.  
      The load power  141  is rated power of W 8   c  of the fuel cell body  131  from t 2  to t 3 , and is W 8   d  smaller than the rated power of the fuel cell body  131  from t 1  to t 2 .  
      On the other hand, in the fuel cell body  131  ( FIG. 13 ), the output control means  133  performs a continuous operation by the rated power W 8   c  from t 2  to t 3 , and performs an intermittent operation by the rated power W 8   c  from t 1  to t 2  so that the same amount of electricity as the load power  141  can be obtained.  
      Therefore, the battery  132  ( FIG. 13 ) puts on charge and discharge the redundant power and the insufficient power in the period from t 1  to t 2 .  
      Since the fuel cell body  131  cannot continue generating power unless a high temperature can be constantly maintained, the energy such as the power for heating the fuel cell body  131  before generating power during power-up is required. Furthermore, since a stopping operation is performed by safely emitting hydrogen remaining in the path while cooling it, the energy such as power, etc. is also required.  
      Since an intermittent operation is performed in the above mentioned conventional fuel cell power generation system (conventional technology  3 ), energy is wasted each time power-up and power-down operations are performed.  
      Although the configuration of the fuel cell power generation system (conventional technology  4 ) is similar to that of the above mentioned fuel cell power generation system (conventional technology  3 ), the waste of the conventional technology can be avoided to a certain extent by changing the output power by following the load power as shown in  FIG. 15  which is a graph for explanation of an example of an operation pattern of the conventional fuel cell power generation system (conventional technology  4 ).  
      In  FIG. 15 , the horizontal and vertical axes respectively indicate the time and the power. Reference numerals  143  and  144  respectively denote load power and output power. The load power  143  is high in the morning  143   b,  afternoon  143   c,  and evening  143   d,  and is low at midnight  143   e  and in the early morning  143   a.    
      The operation of the fuel cell body is controlled by the output power  144  following the load power  143  between the maximum output power W 9   c  and the minimum output power W 9   d.  Since the fuel cell body  1  has a continuously increasing amount of charge of the battery  132  with excess power when the load power  143  is smaller than the minimum output power W 9   d  at midnight  143   e  and in the early morning  143   a,  the operation is stopped.  
      Thus, the conventional fuel cell power generation system (conventional technology  4 ) is generally activated and stopped once a day, thereby more successfully reducing the waste energy during the power-up and power-down than the above mentioned fuel cell power generation system (conventional technology  3 ).  
      (A) However, in the conventional fuel cell power generation device (conventional technology  1 ), when an external load command largely changes within a short time, the power control unit  35  has to control the output power by raising and dropping it within a short time, thereby possibly causing the hunting of output power because of the delay of control. As a result, there can arise the problem that the operation of the fuel cell power generation device becomes unstable, the efficiency of the device is lowered, and the durability is shortened.  
      (B) Additionally, there has been the problem that the fuel cell power generation system (conventional technology  4 ) wastes energy when the operation as shown in  FIG. 16  which is a graph for explanation of an example of another operation pattern of the conventional fuel cell power generation system (conventional technology  4 ) is performed.  
      To be more practical, in the conventional fuel cell power generation system (conventional technology  4 ), when there is a temporary rise  145   b  of load power  145  when the operation is stopped, for example, at midnight  145   e  or in the early morning  145   a , the system is started but stopped soon. Furthermore, in the fuel cell power generation system (conventional technology  4 ), the stopping process is started but the activating process is soon performed when there is a temporary drop  145   d  of the load power  145  during the operation, for example, in the afternoon  145   c , etc. Thus, energy is wasted in the originally unnecessary activating and stopping operations.  
     DISCLOSURE OF THE INVENTION  
      The present invention has been achieved to solve the abovementioned problems with the conventional technology, and aims at providing a power generation control system, a power generation control method, a program, and a medium for preventing the reduction of the durability by, for example, stabilizing the operation of the fuel cell power generation device and improving the efficiency.  
      The present invention has also been achieved to solve the problem with the conventional technology, and aims at providing a power generation control system, a power generation control method, a program, and a medium capable of minimizing the waste of energy even when there arise a temporary rise or drop of power load.  
      The 1st invention of the present invention (corresponding to claim  1 ) is a power generation control system comprising: 
          power detection means of detecting power requested by a load; and     power generation control means of controlling predetermined power generation means of generating all or a part of power to be supplied to the load using a command value generated in each second predetermined period based on an average value of the detected power in a first predetermined period.        

      The 2nd invention of the present invention (corresponding to claim  2 ) is the power generation control system according to the 1st invention of the present invention, wherein the command value generated in each second predetermined period is generated based on an average value in the first predetermined period with a starting time of the second predetermined period as an end time of the first predetermined period.  
      The 3rd invention of the present invention (corresponding to claim  3 ) is the power generation control system according to the 1st or 2nd invention of the present invention, wherein: 
          said predetermined power generation means is a fuel cell; and     excess or shortfall of the generated power relative to the requested power is adjusted using system power and/or battery.        

      The 4th invention of the present invention (corresponding of claim  4 ) is the power generation control system according to the 3rd invention of the present invention, wherein: 
          the excess or shortfall of the generated power can be adjusted using system power and battery; and     said battery is used by priority over said system power.        

      The 5th invention of the present invention (corresponding to claim  5 ) is the power generation control system according to the 3rd invention of the present invention, wherein said control is performed with amount of accumulation of the battery taken into account.  
      The 6th invention of the present invention (corresponding of claim  6 ) is the power generation control system according to the 5th invention of the present invention, wherein said taking an amount of accumulation of the battery into account means amending the command value corresponding to the difference between the amount of accumulation and a predetermined target amount of accumulation.  
      The 7th invention of the present invention (corresponding to claim  7 ) is a power generation control method, comprising the steps of: 
          detecting power requested by a load; and     controlling predetermined power generation means of generating all or a part of power to be supplied to the load using a command value generated in each second predetermined period based on an average value of the detected power in a first predetermined period.        

      The 8th invention of the present invention (corresponding to claim  8 ) is a power generation control system, comprising: 
          power detection means of detecting power requested by a load;     time accumulation means of accumulating a time at which the detected power requested by the load equal to or larger than a predetermined value when predetermined power generation means does not generate power to be supplied to the load; and     power generation control means of allowing said power generation means to start generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 9th invention of the present invention (corresponding to claim  9 ) is the power generation control system according to the 8th invention of the present invention, wherein said predetermined rule refers to allowing said power generation means to start generating power to be supplied to the load when (1) a total period of the time continuously accumulated in a predetermined period or (2) a total period of the time discontinuously accumulated in a predetermined period exceeds a predetermined threshold.  
      The 10th invention of the present invention (corresponding to claim  10 ) is the power generation control system according to the 9th invention of the present invention, wherein said time accumulation means outputs (1) the total period of the time continuously accumulated in the predetermined period or (2) the total period of the time discontinuously accumulated in the predetermined period as a result of the accumulation.  
      The 11th invention of the present invention (corresponding to claim  11 ) is the power generation control system according to the 8th invention of the present invention, wherein said predetermined rule refers to allowing said power generation means to start generating power to be supplied to the load when a total period of continuously accumulated time exceeds a predetermined threshold.  
      The 12th invention of the present invention (corresponding to claim  12 ) is a power generation control system, comprising: 
          power detection means of detecting power requested by a load;     time accumulation means of accumulating a time at which the detected power requested by the load equal to or smaller than a predetermined value when predetermined power generation means generates power to be supplied to the load; and     power generation control means of allowing said power generation means to stop generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 13th invention of the present invention (corresponding to claim  13 ) is a power generation control system, comprising: 
          power detection means of detecting power requested by a load;     power accumulation means of accumulating power requested by the load in a predetermined period when predetermined power generation means does not generate power to be supplied to the load; and     power generation control means of allowing said power generation means to start generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 14th invention of the present invention (corresponding to claim  14 ) is the power generation control system according to the 13th invention of the present invention, wherein said predetermined rule refers to allowing said power generation means to start generating power to be supplied to the load when the accumulated power exceeds a predetermined threshold.  
      The 15th invention of the present invention (corresponding to claim  15 ) is a power generation control system, comprising: 
          power detection means of detecting power requested by a load;     power accumulation means of accumulating power requested by the load in a predetermined period when predetermined power generation means generates power to be supplied to the load; and     power generation control means of allowing the power generation means to stop generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 16th invention of the present invention (corresponding to claim  16 ) is a power generation control system, comprising: 
          record accumulation means of accumulating a record of power requested by a load when predetermined power generation means generates power to be supplied to the load according to a predetermined rule; and     power generation control means of allowing the power generation means to start or stop generating power to be supplied to the load according to the accumulated record by priority over the rule.        

      The 17th invention of the present invention (corresponding to claim  17 ) is the power generation control system according to the 16th invention of the present invention, wherein: 
          a time at which said power generation means is allowed to start or stop generating power to be supplied to the load is computed based on the accumulated record; and     said power generation means is allowed to start or stop generating power to be supplied to the load practically at the computed time.        

      The 18th invention of the present invention (corresponding to claim  18 ) is a power generation control method, comprising the steps of: 
          detecting power requested by a load;     accumulating a time at which the detected power requested by the load indicates a value equal to or larger than a predetermined value when predetermined power generation means does not generate power to be supplied to the load; and     allowing said power generation means to start generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 19th invention of the present invention (corresponding to claim  19 ) is a power generation control method, comprising the steps of: 
          detecting power requested by a load;     accumulating a time at which the detected power requested by the load indicates a value equal to or smaller than a predetermined value when predetermined power generation means generates power to be supplied to the load; and     allowing said power generation means to stop generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 20th invention of the present invention (corresponding to claim  20 ) is a power generation control method, comprising the steps of: 
          detecting power requested by a load;     accumulating power requested by the load in a predetermined period when predetermined power generation means does not generate power to be supplied to the load; and     allowing said power generation means to start generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 21st invention of the present invention (corresponding to claim  21 ) is a power generation control method, comprising the steps of: 
          detecting power requested by a load;     accumulating power requested by the load in a predetermined period when predetermined power generation means generates power to be supplied to the load; and     allowing the power generation means to stop generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 22nd invention of the present invention (corresponding to claim  22 ) is a power generation control method, comprising the steps of: 
          accumulating a record of power requested by a load when predetermined power generation means generates power to be supplied to the load according to a predetermined rule; and     allowing the power generation means to start or stop generating power to be supplied to the load according to the accumulated record by priority over the rule.        

      The 23rd invention of the present invention (corresponding to claim  23 ) is a program being used to direct a computer to function as all or a part of the power generation control system according to the 1st invention of the present invention, comprising: 
          power detection means of detecting power requested by a load; and     power generation control means of controlling predetermined power generation means of generating all or a part of power to be supplied to the load using a command value generated based on an average value of the detected power in a first predetermined period in each second predetermined period.        

      The 24th invention of the present invention (corresponding to claim  24 ) is a program being used to direct a computer to function as all or a part of the power generation control system according to the 8th invention of the present invention, comprising: 
          power detection means of detecting power requested by a load;     time accumulation means of accumulating a time at which the detected power requested by the load indicates a value equal to or larger than a predetermined value when predetermined power generation means does not generate power to be supplied to the load; and     power generation control means of allowing said power generation means to start generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 25th invention of the present invention (corresponding to claim  25 ) is a program being used to direct a computer to function as all or a part of the power generation control system according to the 12nd present invention, comprising: 
          power detection means of detecting power requested by a load;     time accumulation means of accumulating a time at which the detected power requested by the load indicates a value equal to or smaller than a predetermined value when predetermined power generation means generates power to be supplied to the load; and     power generation control means of allowing said power generation means to stop generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 26th invention of the present invention (corresponding to claim  26 ) is a program being used to direct a computer to function as all or a part of the power generation control system according to the 13th present invention, comprising: 
          power detection means of detecting power requested by a load;     power accumulation means of accumulating power requested by the load in a predetermined period when predetermined power generation means does not generate power to be supplied to the load; and     power generation control means of allowing said power generation means to start generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 27th invention of the present invention (corresponding to claim  27 ) is a program being used to direct a computer to function as all or a part of the power generation control system according to the  15 th invention of the present invention, comprising 
          power detection means of detecting power requested by a load;     power accumulation means of accumulating power requested by the load in a predetermined period when predetermined power generation means generates power to be supplied to the load; and     power generation control means of allowing the power generation means to stop generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 28th invention of the present invention (corresponding to claim  28 ) is a program being used to direct a computer to function as all or a part of the power generation control system according to claim  16 , comprising: 
          record accumulation means of accumulating a record of power requested by a load when predetermined power generation means generates power to be supplied to the load according to a predetermined rule; and     power generation control means of allowing the power generation means to start or stop generating power to be supplied to the load according to the accumulated record by priority over the rule.        

      The 29th invention of the present invention (corresponding to claim  29 ) is a computer-processible medium storing a program being used to direct a computer to function as all or a part of the power generation control system according to the  1 st invention of the present invention, comprising: 
          power detection means of detecting power requested by a load; and     power generation control means of controlling predetermined power generation means of generating all or a part of power to be supplied to the load using a command value generated based on an average value of the detected power in a first predetermined period in each second predetermined period.        

      The 30th invention of the present invention (corresponding to claim  30 ),is a computer-processible medium storing a program being used to direct a computer to function as all or a part of the power generation control system according to the  8 th invention of the present invention, comprising: 
          power detection means of detecting power requested by a load;     time accumulation means of accumulating a time at which the detected power requested by the load indicates a value equal to or larger than a predetermined value when predetermined power generation means does not generate power to be supplied to the load; and     power generation control means of allowing said power generation means to start generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 31st invention of the present invention (corresponding to claim  31 ) is a computer-processible medium storing a program being used to direct a computer to function as all or a part of the power generation control system according to the 12th invention of the present invention, comprising: 
          power detection means of detecting power requested by a load;     time accumulation means of accumulating a time at which the detected power requested by the load indicates a value equal to or smaller than a predetermined value when predetermined power generation means generates power to be supplied to the load; and     power generation control means of allowing said power generation means to stop generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 32nd invention of the present invention (corresponding to claim  32 ) is a computer-processible medium storing a program being used to direct a computer to function as all or a part of the power generation control system according to the 13th invention of the present invention, comprising: 
          power detection means of detecting power requested by a load;     power accumulation means of accumulating power requested by the load in a predetermined period when predetermined power generation means does not generate power to be supplied to the load; and     power generation control means of allowing said power generation means to start generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 33rd invention of the present invention (corresponding to claim  33 ) is a computer-processible medium storing a program being used to direct a computer to function as all or a part of the power generation control system according to the 15th invention of the present invention, comprising: 
          power detection means of detecting power requested by a load;     power accumulation means of accumulating power requested by the load in a predetermined period when predetermined power generation means generates power to be supplied to the load; and     power generation control means of allowing the power generation means to stop generating the power to be supplied to the load using a predetermined rule based on the accumulation result.        

      The 34th invention of the present invention (corresponding to claim  34 ) is a computer-processible medium storing a program being used to direct a computer to function as all or a part of the power generation control system according to the 16th invention of the present invention, comprising: 
          record accumulation means of accumulating a record of power requested by a load when predetermined power generation means generates power to be supplied to the load according to a predetermined rule; and     power generation control means of allowing the power generation means to start or stop generating power to be supplied to the load according to the accumulated record by priority over the rule.       

    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a configuration of a system of a fuel cell power generation device according to a first embodiment of the present invention;  
       FIG. 2  shows a configuration of a system of a fuel cell power generation device according to a second embodiment of the present invention;  
       FIG. 3  shows a controlling operation of the fuel cell power generation device according to the first embodiment of the present invention;  
       FIG. 4  shows a controlling operation of the fuel cell power generation device according to the second embodiment of the present invention;  
       FIG. 5  is a graph for explanation of an example of an operation pattern of a fuel cell power generation system according to a third embodiment of the present invention;  
       FIG. 6  is a graph for explanation of an example of an operation pattern of a fuel cell power generation system according to a fourth embodiment of the present invention;  
       FIG. 7  is a graph for explanation of an example of an operation pattern of a fuel cell power generation system according to a fifth embodiment of the present invention;  
       FIG. 8  is a graph for explanation of an example of an operation pattern of a fuel cell power generation system according to a sixth embodiment of the present invention;  
       FIG. 9  is a graph for explanation of an example of an stopping pattern of a fuel cell power generation system according to a seventh embodiment of the present invention;  
       FIG. 10  shows a configuration of the system of the fuel cell power generation system according to the third embodiment of the present invention;  
       FIG. 11  shows a configuration of a system of a conventional fuel cell power generation device (conventional technology  1 );  
       FIG. 12  shows a configuration of a system of a conventional fuel cell power generation device (conventional technology  2 );  
       FIG. 13  shows a configuration of a system of a conventional fuel cell power generation system (conventional technology  3 );  
       FIG. 14  is a graph for explanation-of an example of an operation pattern of a conventional fuel cell power generation system (conventional technology  3 );  
       FIG. 15  is a graph for explanation of an example of an operation pattern of a conventional fuel cell power generation system (conventional technology  4 ); and  
       FIG. 16  is a graph for explanation of another example of an operation pattern of a conventional fuel cell power generation system (conventional technology  4 ). 
    
    
     DESCRIPTION OF SYMBOLS  
       1  fuel cell body  
       2  hydrogen supply means  
       3  air supply means  
       4  output control means  
       5  power conversion device  
       6  output line  
       7  system power  
       8  load detection means  
       9  power load  
       10  output command device  
       11  flow rate control device  
       12  system power connection line  
       21  accumulation means  
       22  connection line  
       23  accumulation amount control device  
       24  accumulation amount detection means  
     BEST MODE FOR CARRYING OUT THE INVENTION  
      The embodiments according to the present invention will be described below by referring to the attached drawings.  
     EMBODIMENT 1  
      First, a configuration of a fuel cell power generation device according to a first embodiment of the present invention will be described below by referring to  FIG. 1  showing the configuration of the system of the fuel cell power generation device according to the first embodiment of the present invention.  
      To a fuel cell body  1 , hydrogen supply means  2  represented by a reformer, a hydrogen storage alloy, a hydrogen bomb, etc., and air supply means  3  represented by an air blower, a blower pump, etc. are connected. One terminal of output control means  4  is electrically connected to the fuel cell body  1 , and another terminal is electrically connected to a power conversion device  5 . An output line  6  is electrically connected to the power conversion device  5 , branched in the line, one terminal is electrically connected to a system power  7  through a system power connection line  12  while another terminal is electrically connected to load detection means  8  and a power load  9 . Output command device  10  issues an output command to the output control means  4 , and a flow rate control device  11  controls the hydrogen supply means  2  and the air supply means  3 .  
      The output control means  4 , the output command device  10 , and the means including the flow rate control device  11  correspond to the power generation control means according to the present invention, and the load detection means  8  corresponds to power detection means according to the present invention. The fuel cell power generation device according to the first embodiment of the present invention corresponds to means including the power generation control system according to the present invention.  
      Described below will be the operation of the fuel cell power generation device according to the first embodiment of the present invention. While describing the operation of the fuel cell power generation system according to the first embodiment of the present invention, an embodiment of the power generation control method according to the present invention is also described (as in the following descriptions).  
      The hydrogen supplied by the hydrogen supply means  2  reacts with the oxygen in the air supplied by the air supply means  3  in the fuel cell body  1  to generate DC power. The amount of electricity of the generated DC power is controlled by the output control means  4 , then transmitted to the power conversion device  5 , converted into AC power having the same voltage as the system power  7 , and supplied to the power load  9  through the output line  6 . At this time, power conversion efficiency indicates how the input power into the power conversion device  5  is converted into the output power from the power conversion device  5 . If the output power of the fuel cell body  1  is short relative to the load power of the power load  9 , the power is also supplied by the system power  7 . On the other hand, if the output power is excessive relative to the load power, then the power is returned to the system power  7 , thereby performing a system linkage operation.  
      An object of the power generation by a fuel cell power generation device is to obtain the economical efficiency by the high efficiency. However, when the output power is short relative to the load power, power is purchased from the system power  7 . On the other hand, when the output power is excessive relative to the load power, the purchased power is returned at a low price to the system power  7 , thereby normally lowering the economical efficiency. Therefore, it is demanded that the output power can closely follow the change of the load power such that the output power can be prepared in proper quantities relative to the load power.  
      As means of following the load power, the load detection means  8  first detects the load power of the power load  9 . Based on the detection result, the output command device  10  issues an output command value to the output control means  4 , the output control means  4  controls the DC power generated by the fuel cell body  1  at the request value. Depending on the DC power value, the flow rate control device  11  controls the hydrogen flow rate from the hydrogen supply means  2  and the air flow rate from the air supply means  3  at the appropriate value. The output power can be controlled only by the output control means  4  performing the DC power control. However, if the hydrogen flow rate to the fuel cell body  1  is constant, and a smaller amount of DC power is generated by the fuel cell body  1 , then the ratio of the hydrogen (hydrogen utilization rate) reacting in the fuel cell body  1  is reduced and a large volume of hydrogen is wasted, thereby exceedingly lowering the efficiency. Thus, by the flow rate control device  11  controlling the hydrogen flow rate and the air flow rate at the appropriate value, the efficiency can be optimally maintained.  
      In a series of following controlling processes, the load power can incessantly change within a short time. If the load power is used as an output command as is, the DC power rises or drops within a short time, thereby causing the trouble that the delay of control induces hunting and an unstable operation of the fuel cell power generation device. Furthermore, when a reformer for generating hydrogen from a hydrocarbon fuel by catalysis is used as the hydrogen supply means  2 , the process by catalysis cannot follow an instant change of an output command value, thereby causing the problem of lowered efficiency and reduced durability.  
      According to an embodiment of the present invention, as shown in  FIG. 3  showing the fuel cell power generation device according to the first embodiment of the present invention, the output command device  10  computes an output command by obtaining an average value of the load power in the period of time T 1  (first predetermined period) with the power conversion efficiency taken into account, and sets the output command value as a DC power value to be set by the output control means  4  every time T 2  (second predetermined period). Using the average value of the load power in the time T 1  for an output command value, an appropriate output command can be issued regardless of an instant change, and using an output command every time T 2 , the device can be operated depending on its response time (time T 2  (second predetermined period) (The command value generated each time T 2  (second predetermined period) is based on the average value in the period of the time T 1  (first predetermined period) ending at the starting time of the second predetermined period.  
      As an example, when the optimum control value in the domestic operation of a solid polymer fuel cell power generation device of 1.5 KW output is obtained, a result of T 1 =3 minutes and T 2 =1 minute indicating T 1 :T 2 =approximately 3:1 is output. That is, in this example, the optimum operation control can be performed by issuing an output command value based on an average load power in 3 minutes to a device each minute.  
      Thus, according to the first embodiment of the present invention, the optimum output command can be issued regardless of an instant change by applying an average value in the period of the time T 1  of the load power to an output command value, and an operation of a device can be optimally performed corresponding to the response time of the device by issuing an output command each time T 2 . As a result, the fuel cell power generation device can be stably operated with high efficiency and longer durability.  
     EMBODIMENT 2  
      The configuration of the fuel cell power generation device according to a second embodiment of the present invention will be described below by referring to  FIG. 2  showing the configuration of the system of the fuel cell power generation device according to a second embodiment of the present invention. The means also appearing in the above mentioned first embodiment is assigned the same reference numeral, and the explanation is omitted here.  
      Accumulation means  21  is branched from a connection line  22  connecting the output control means  4  to the power conversion device  5 , and connected through an accumulation amount control device  23 . Accumulation amount detection means  24  is connected to the accumulation means  21 . An object of providing the accumulation means  21  is to solve the problem with the first embodiment that the economical efficiency is reduced in the system linkage operation by adjusting the power relating to the system power  7  due to the excess or deficient output power relative to the load power. That is, using the charge/discharge of the accumulation means  21 , the amount of power supply from the system power  7  and the amount of return power to the system power  7  can be minimized, thereby improving the economical efficiency (the accumulation means  21  (battery) is used by priority over the system power  7 ).  
      Described below will be the operation of the fuel cell power generation device according to the second embodiment of the present invention. As shown in  FIG. 4 , the output command device  10  operates an average power W 1  in the period of time T 1  of the load power detected by the load detection means  8 . The power W 2  (=Q 3 /T 2 ) is obtained by dividing the shortage of accumulation Q 3  (=Q 2 −Q 1 ) which is a difference between the current amount of accumulation Q 1  detected by the accumulation amount detection means  24  and the target amount of accumulation Q 2  by the time T 2 . The power W 2  is added to the average power W 1  to obtain W 3  (=W 1 +W 2 ). Then, an output command value is obtained from the W 3  with the power conversion efficiency taken into account, and the DC power value of the fuel cell body  1  corresponding to the output command value is issued to the output control means  4  each time T 2 . The output command value is defined as the DC power value set each time T 2  by the output control means  4 . In addition, the shortage of accumulation Q 3  is controlled to be accumulated in the accumulation means  21  by the accumulation amount control device  23  (a command value is amended depending on the difference between an amount of accumulation and a predetermined target amount of accumulation).  
      The series of the above mentioned controlling operations are performed by adding the accumulation amount control to the following control (refer to  FIG. 3 ) according to the first embodiment of the present invention. When the average power W 1  is defined as an output command value as is, then the amount of accumulation is not controlled, thereby possibly accumulating the difference between the target amount of accumulation Q 2  and the current amount of accumulation Q 1  gradually. For example, when the amount of accumulation gradually decreases with the amount of discharge exceeding the amount of charge, the accumulation means  21  of a large capacity is to be prepared not to reduce the amount of accumulation down to zero, thereby requiring the higher cost and larger device installation space. Therefore, according to the second embodiment of the present invention, an output command value is obtained by taking the power conversion efficiency into account for W 3  (=W 1 +W 2 ) obtained by adding the power W 2  (=Q 3 /T 2 ) compensating for the shortage of accumulation Q 3  (=Q 2 −Q 1 ) in the time period T 2  for specification of the output command value. Thus, the amount of accumulation is controlled to constantly converge into the target amount of accumulation Q 2 , thereby minimizing the requirements for the accumulation means  21 .  
      Thus, according to the second embodiment of the present invention, the requirements for the accumulation means  21  can be minimized by controlling the amount of accumulation to converge into the target amount of accumulation Q 2 , thereby reducing the cost and size of the device.  
      In the above mentioned first and second embodiments of the present invention, the predetermined period T 1  used for obtaining the average power W 1  and the predetermined period T 2  used for issuing a command value to the output control means can satisfy the expression of T 1 ≧T 2  (where T 1  can be a period equal to or longer than 1 second, and equal to or shorter than 1 hour).  
     EMBODIMENT 3  
      Then, the configuration of the fuel cell power generation system according to a third embodiment of the present invention is described below by referring to  FIG. 10  showing the configuration of the fuel cell power generation system of the third embodiment of the present invention.  
      In  FIG. 10 , the host  101 , output control means  102 , and load detection means  103  are serially connected in this order, a load  104  wastes the power connected to the load detection means  103 , and a battery  105  is branched and connected from the connection portion between the output control means  102  and the load detection means  103 .  
      The fuel cell body  101  corresponds to means including the power generation means according to the present invention, the load detection means  103  corresponds to means including the power detection means according to the present invention, the output control means  102  corresponds to means including the power generation control means and the time accumulation means according to the present invention. The fuel cell power generation system according to the third embodiment of the present invention corresponds to means including the power generation control system according to the present invention.  
      Then, the operations of the fuel cell power generation system according to the third embodiment of the present invention are described below by referring to  FIG. 5  showing a graph for explanation of an example of an operation pattern of the fuel cell power generation system according to the third embodiment of the present invention.  
      The output control means  102  controls the activation stop of the system, and the output power of the fuel cell body  101  so that the power of the load  104  detected by the load detection means  103  can be followed (when the output power of the fuel cell body  101  cannot follow the power of the load  104 , the excess power and shortfall power are buffered by the charge and discharge of the battery  105 ).  
      An example of an operation pattern shown in  FIG. 5  is a model of an operation pattern of a common home in a day. The horizontal and vertical axes respectively indicate time and power. Reference numerals  111  and  112  respectively denote load power and output power.  
      Load power  111  is high in the morning  111   b,  afternoon  111   c,  and evening  111   d,  and low at midnight  111   e  and in the early morning  111   a.    
      On the other hand, the operation of the fuel cell body  101  is controlled by the output control means  102  such that the output power  112  following the load power  111  can be obtained between maximum output power W 1   c  and minimum output power W 1   d.    
      According to the third embodiment of the present invention, when the load power  111  transfers, for example, from the low level in the early morning  111   a,  etc. to the high level in the morning  111   b,  etc., and when the load power not less than a predetermined value W 1   a  is maintained for not less than a predetermined time T 1   a,  the system is activated. In contrast, when the load power  111  transfers, for example, from the high level in the evening  111   d,  etc. to the low level at midnight  111   e,  etc., and, for example, when the load power lower than a predetermined value W 1   b  is maintained for not less than a predetermined time T 1   b,  the system is stopped.  
      Although there arises an instant rise or drop of a power load, an unnecessary activating (stopping) operation can be prevented by the control of the operation in which power generation is started (or stopped) when continuously accumulated time exceeds (or falls below) a predetermined threshold, thereby successfully performing one activating (stopping) operation in one day. That is, the waste of energy during the activating/stopping operation can be minimized.  
     EMBODIMENT 4  
      The configuration and the operation of the fuel cell power generation system according to the fourth embodiment of the present invention is described below by referring to  FIG. 6  which is a graph for explanation of an example of an operation pattern of the fuel cell power generation system according to the fourth embodiment of the present invention.  
      The configuration and the operations of the fuel cell power generation system according to the fourth embodiment of the present invention are similar to the configuration and the operations of the fuel cell power generation system according to the third embodiment of the present invention. In  FIG. 6 , the horizontal and vertical axes respectively indicate time and power. Reference numerals  113  and  114  respectively denote load power and output power. The load power  113  is high in the morning  113   b , afternoon  113   c , and evening  113   d , and is low at midnight  113   e  and in the early morning  113   a.    
      However, according to the fourth embodiment of the present invention, the operation of the fuel cell body is controlled by the output control means such that the output power  114  following the load power  113  can be obtained between maximum output power W 2   c  and minimum output power W 2   d.    
      When the load power  113  transfers from the low level in the early morning  113   a , etc. to the high level in the morning  113   b , etc., and when the load power not less than a predetermined value W 2   a  is generated at a predetermined or higher ratio R 2   a  in a predetermined time T 2   a , the system is activated. When the load power  113  transfers from the high level in the evening  113   d , etc. to the low level at midnight  113   e , and when the load power at or below a predetermined value W 2   b  is generated at a predetermined or higher ratio R 2   b  in a predetermined time T 2   b , the system is stopped.  
      For example, when R 2   a= 70%, the system is activated when the load power at or over the predetermined value W 2   a  is generated over 70% in the predetermined time T 2   a  in the activating operation. Therefore, an instant value of the load power  113  falls not more than W 2   a  in the activation discrimination time (T 2   a ) in  113   f , it is ignored (little influenced). In contrast, when R 2   b= 70   %, the system is stopped when the load power at or below the predetermined value W 2   b  is generated over 70% in the predetermined time T 2   b  in the stopping operation. Therefore, an instant value of the load power  113  falls not less than W 2   b  in the stop discrimination time (T 2   b ) in  113   g , it is ignored.  
      As described above, by controlling the operation of starting (stopping) generation of power when (1) the total period of continuously accumulated time or (2) the total period of discontinuously accumulated time exceeds (falls below) a predetermined threshold, an unnecessary activating (stopping) operation can be prevented, and one activating (stopping) operation can be performed in one day. That is, the waste of energy during the activating/stopping operation can be minimized (it is obvious that the output of the time accumulation means (corresponding to the means included in the output control means according to the fourth embodiment) according to the present invention can be a total time in a predetermined period, or can be each time before computing the total value).  
      Furthermore, as compared with the above mentioned third embodiment of the present invention, the required amount of accumulation of the battery can be reduced by reducing the shortfall of the power due to the delay of activation or the excess power due to the delay of a stopping operation, thereby realizing a lower cost system.  
     EMBODIMENT 5  
      The configuration and the operation of the fuel cell power generation system according to a fifth embodiment of the present invention will be described below by referring to  FIG. 7  which is a graph for explanation of an example of an operation pattern of the fuel cell power generation system according to the fourth embodiment of the present invention.  
      The configuration and the operations of the fuel cell power generation system according to the fourth embodiment of the present invention are similar to the configuration and the operations of the fuel cell power generation system according to the third embodiment of the present invention (the output control means according to the fifth embodiment corresponds to the power generation control means and power accumulation means according to the present invention). In  FIG.7 , the horizontal and vertical axes respectively indicate time and power. Reference numerals  115  and  116  respectively denote load power and output power. The load power  115  is high in the morning  115   b , afternoon  115   c , and evening  115   d , and is low at midnight  115   e  and in the early morning  115   a.    
      However, according to the fourth embodiment of the present invention, the operation of the fuel cell body is controlled by the output control means such that the output power  116  following the load power  115  can be obtained between maximum output power W 3   c  and minimum output power W 3   d.    
      When the load power  115  transfers from the low level in the early morning  115   a , etc. to the high level in the morning  115   b , etc., and when the average load power obtained by dividing a load power accumulation amount by a time exceeds a predetermined value W 3   a  in a predetermined time T 3   a , the system is activated. When the load power  115  transfers from the high level in the evening  115   d , etc. to the low level at midnight  115   e , and when the average load power obtained by dividing a load power accumulation amount by a time falls not more than a predetermined value W 3   b  in a predetermined time T 3   b , the system is stopped.  
      Therefore, a value of the load power  115  falls for a moment in the activation discrimination time (T 3   a ) in  115   f , it is ignored. Likewise, a value of the load power  115  rises for a moment in the stop discrimination time (T 3   b ) in  115   g , it is ignored.  
      Thus, by controlling the operation of starting (stopping) generation of power when the accumulated power exceeds (falls below) a predetermined threshold, an unnecessary activating (stopping) operation can be prevented, and one activating (stopping) operation can be performed in one day. That is, the waste of energy during the activating/stopping operation can be minimized.  
      Furthermore, the delay of activation and stop can be reduced as compared with the cases according to the above mentioned third embodiment and the required amount of accumulation of the battery can be reduced by reducing the shortfall of the power due to the delay of activation or the excess power due to the delay of a stopping operation, thereby realizing a lower cost system.  
     EMBODIMENT 6  
      The configuration and the operation of the fuel cell power generation system according to the fourth embodiment of the present invention is described below by referring to  FIG. 8  which is a graph for explanation of an example of an operation pattern of the fuel cell power generation system according to the fourth embodiment of the present invention.  
      The configuration and the operations of the fuel cell power generation system according to the fourth embodiment of the present invention are similar to the configuration and the operations of the fuel cell power generation system according to the third embodiment of the present invention (the output control means according to the fifth embodiment corresponds to the power generation control means and means including record accumulation means according to the present invention). In  FIG. 8 , the horizontal and vertical axes respectively indicate time and power.  
      However, the output control means according to the present invention computes the optimum daily activation time B with the time at which system was to be activated taken into account, and when predetermined number of days in the stored optimum activation time B enters the range of a predetermined time T 4   a , it computes an average time B 0  of the optimum activation times B, and activates the system (reference numerals  117  and  118  respectively denote load power including values for the days, and output power also including values for the days).  
      By performing, with advantage over a predetermined rule (for example, a rule in one of the above mentioned conventional technologies can be used) for generating power, the control of the start of generating power based on the accumulated record, the delay of activation can be reduced as compared with the cases according to the above mentioned third through fifth embodiments, and the required amount of accumulation of the battery can be further reduced.  
     EMBODIMENT  7)    
      The configuration and the operation of the fuel cell power generation system according to the fourth embodiment of the present invention is described below by referring to  FIG. 9  which is a graph for explanation of an example of a stopping pattern of the fuel cell power generation system according to the fourth embodiment of the present invention.  
      The configuration and the operations of the fuel cell power generation system according to the fourth embodiment of the present invention are similar to the configuration and the operations of the fuel cell power generation system according to the third embodiment of the present invention. In  FIG. 9 , the horizontal and vertical axes respectively indicate time and power.  
      However, the output control means according to the present invention computes the optimum daily stop time D with the time at which system was to be stopped taken into account, and when predetermined number of days in the stored optimum stop time D enters the range of a predetermined time T 5   b , it computes an average time DO of the optimum stop times D, and stops the system (reference numerals  119  and  120  respectively denote load power including values for the days, and output power also including values for the days).  
      By performing, with advantage over a predetermined rule for generating power, the control of the end of generating power based on the accumulated record, the delay of stop can be reduced as compared with the cases according to the above mentioned third through fifth embodiments, and the requirements for the battery can be further reduced.  
      Described above are the first to seventh embodiment of the present invention.  
      In short, the present invention includes a power generation control system which comprises power detection means of detecting power requested by a load and power generation control means of controlling predetermined power generation means of generating all or a part of power to be supplied to a load using a command value generated based on an average value of the detected power in a first predetermined period in each second period (it is obvious that the predetermined power generation means is a fuel cell, and the excess or shortfall of the generated power relative to the requested power is adjusted using system power and/or battery).  
      The present invention also includes a power generation control system which comprises power detection means of detecting power requested by a load, time accumulation means of accumulating a time at which power requested by the detected load indicates a value equal to or larger than a predetermined value when predetermined power generation means does not generate power to be supplied to the load, and power generation control means of allowing the power generation means to start generating the power to be supplied to the load using a predetermined rule based on an accumulation result.  
      The present invention also includes a power generation control system which comprises power detection means of detecting power requested by a load, time accumulation means of accumulating a time at which power requested by the detected load indicates a value equal to or smaller than a predetermined value when predetermined power generation means generates power to be supplied to the load, and power generation control means of allowing the power generation means to stop generating the power to be supplied to the load using a predetermined rule based on an accumulation result.  
      The present invention also includes a power generation control system which comprises power detection means of detecting power requested by a load, power accumulation means of accumulating power requested by the load in a predetermined period when predetermined power generation means does not generate power to be supplied to the load, and power generation control means of allowing the power generation means to start generating the power to be supplied to the load using a predetermined rule based on an accumulation result.  
      The present invention also includes a power generation control system which comprises power detection means of detecting power requested by a load, power accumulation means of accumulating power requested by the load in a predetermined period when predetermined power generation means generates power to be supplied to the load, and power generation control means of allowing the power generation means to stop generating the power to be supplied to the load using a predetermined rule based on an accumulation result.  
      The present invention further includes a power generation control system which comprises record accumulation means of accumulating a record of power requested by the load when predetermined power generation means generates power to be supplied to the load according to a predetermined rule, and power generation control means of allowing the power generation means to start or stop generating power to be supplied to the load according to the accumulated record by priority over the rule.  
      The present invention can also be a program used to direct a computer to perform the functions of all or a part of means (or devices, elements, circuits, units, etc.) of the power generation control system according to the present invention, and a program cooperating with the computer. It is obvious that the computer according to the present invention can include not only purely hardware such as a CPU but also firmware, an OS, and peripheral units.  
      Furthermore, the present invention can also be a program used to direct a computer to perform the operations of all or apart of steps (or processes, operations, effects, etc.) of the power generation control method according to the present invention, and a program cooperating with the computer.  
      A part of the means (or devices, elements, circuits, unit, etc.) of the present invention, and a part of the steps (or processes, operations, effects, etc.) indicate some means or steps in the plurality of means or steps, or a part of the functions or a part of the operations in one means or step.  
      A part of the devices (or elements, circuit, units, etc.) of the present invention indicate some devices in the plurality of devices, or a part of the means (or elements, circuits, units, etc.) in one device, or indicate a part of the functions in one means.  
      The present invention further includes a computer-readable storage medium storing a program according to the present invention. An embodiment of the program according to the present invention can be stored in a computer-readable storage medium, and coordinate with the computer. An embodiment of the program according to the present invention can also be transmitted through a transmission medium, read by the computer, and cooperate with the computer. A storage medium can be ROM, etc., and a transmission medium can be a transmission medium such as Internet, etc., light, electric wave, sound wave, etc.  
      The configuration of the present invention can be realized by either software or hardware.  
      The present invention can also be a storage medium storing program used to direct a computer to perform the functions of all or a part of means of all or a part of the power generation control system according to the present invention, and a computer-readable storage medium, and the program can cooperate with the computer to perform the above mentioned functions.  
      The present invention can also be a storage medium storing program used to direct a computer to perform the operations of all or a part of steps of all or a part of the power generation control method according to the present invention, and a computer-readable storage medium, and the program can cooperate with the computer to perform the above mentioned operations.  
      Thus, the present invention is a fuel cell power generation system comprising, for example, a fuel cell body, and output control means of activating/stopping the system and controlling output power of the fuel cell body such that the load power detected by load detection means can be followed, activates the system when the load power not less than a predetermined value W 1   a  continues longer than a predetermined time T 1   a,  and stops the system when the load power lower than a predetermined value W 1   b  continues longer than a predetermined time T 1   b.    
      Additionally, the present invention is a fuel cell power generation system comprising, for example, a fuel cell body, and output control means of activating/stopping the system and controlling output power of the fuel cell body such that the load power detected by load detection means can be followed, activates the system when load power not less than a predetermined value W 2   a  is generated at a ratio higher than a predetermined ratio R 2   a  in a predetermined time T 2   a , and stops the system when load power not more than a predetermined value W 2   b  is generated at a ratio higher than a predetermined ratio R 2   b  in a predetermined time T 2   b.    
      Furthermore, the present invention is a fuel cell power generation system comprising, for example, a fuel cell body, and output control means of activating/stopping the system and controlling output power of the fuel cell body such that the load power detected by load detection means can be followed, activates the system when the average load power obtained by dividing a load power accumulation amount by a time exceeds a predetermined value W 3   a  in a predetermined time T 3   a , and stops the system when the average load power obtained by dividing a load power accumulation amount by a time falls below a predetermined value W 3   b  in a predetermined time T 3   b.    
      The present invention is the fuel cell power generation system which sets an optimum activation time at a daily activation time, and activates the system at an average time of the optimum activation time when the difference among the optimum activation times stored every day becomes in the range of a predetermined time T 4   a.    
      The present invention is the fuel cell power generation system which sets an optimum stop time at a daily stop time, and stops the system at an average time of the optimum stop time when the difference among the optimum stop times stored every day becomes in the range of a predetermined time T 5   b.    
      Furthermore, the present invention is a fuel cell power generation device characterized by a configuration of, for example, a fuel cell stack for generating DC power by having the hydrogen supplied by hydrogen supply means react with oxygen in the air supplied by air supply means, a power control device for controlling the DC power generated by the fuel cell stack, a flowrate control device for controlling the hydrogen flow rate supplied by the hydrogen supply means depending on the DC power value set by the power control device, and the air flow rate supplied by air supply means, a power conversion device for converting the DC power generated by the fuel cell stack into the AC power of substantially the same voltage as the system power, an output line for connecting the power conversion device with an external power load, load power detection means of detecting external load power, a system power connection line for connecting the output line with the system power, and an output command device connected to the power control device and the load power detection means. With the configuration, the output command device computes the average power W 1  in the time period T 1  of the load power detected by the load power detection means, adds the power conversion efficiency, etc. to the W 1  to obtain an output command value, and sets the output command value as a DC power value set each time T 2  by the power control device.  
      Furthermore, the present invention is a fuel cell power generation device characterized by a configuration of, for example, a fuel cell stack for generating DC power by having the hydrogen supplied by hydrogen supply means react with oxygen in the air supplied by air supply means, a power control device for controlling the DC power generated by the fuel cell stack, a flow rate control device for controlling the hydrogen flow rate supplied by the hydrogen supply means depending on the DC power value set by the power control device, and the air flow rate supplied by air supply means, a power conversion device for converting the DC power generated by the fuel cell stack into the AC power of substantially the same voltage as the system power, an output line for connecting the power conversion device with an external power load, load power detection means of detecting external load power, a system power connection line for connecting the output line with the system power, a accumulation amount control device branched and connected from the connection line connecting the power control device with the power conversion device, accumulation amount detection means, accumulation means, and an output command device connected to the power control device, the load power detection means, the accumulation amount control device, and the accumulation amount detection means. With the configuration, the accumulation amount control device controls the output command device to compute the average power W 1  in the time period T 1  of the load power detected by the load power detection means, obtain W 3  (=W 1 +W 2 ) by adding the power W 2  (=Q 3 /T 2 ) obtained by dividing the shortage of accumulation Q 3  (=Q 2 −Q 1 ), which is the difference between the current amount of accumulation Q 1  detected by the accumulation amount detection means and the target amount of accumulation Q 2  by the time T 2 , to the W 1 , add the power conversion efficiency, etc. to the W 3  as an output command value, and accumulate the shortage of accumulation Q 3  in the accumulation means.  
      Thus, although there arises an instant rise or drop of a power load, an unnecessary activating/stopping operation can be prevented, thereby successfully performing one activating and stopping operation in one day. That is, the waste of energy during the activating/stopping operation can be minimized.  
      Additionally, the required amount of accumulation of the battery can be reduced by reducing the shortfall of the power due to the delay of activation or the excess power due to the delay of a stopping operation, thereby realizing a lower cost system.  
      The entire disclosure of the above mentioned documents are incorporated herein by reference in its entirety.  
      INDUSTRIAL APPLICABILITY  
      As described above, it is apparent that the present invention has the merit of improving the efficiency and suppressing the reduction of the durability by, for example, guaranteeing a stable operation of a fuel cell power generation device.  
      Furthermore, the present invention has also a merit of minimizing the waste of energy in generating a fuel power although there arises an instant rise or drop of a power load.