Patent Publication Number: US-2013234654-A1

Title: Apparatus for controlling electricity accumulation apparatus, electricity accumulation apparatus and method of charging and discharging electricity accumulation apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to an apparatus for controlling an electricity accumulation apparatus, an electricity accumulation apparatus, and a method of charging and discharging an electricity accumulation apparatus. 
     BACKGROUND ART 
     A recent increase in the awareness of global environment protection has drawn attention to a distributed generation such as a solar photovoltaic power generation. An inverse load flow is performed in which excessively-generated electric power, not consumed by a customer, in electric power generated by the distributed generation, inversely flows to a commercial power grid (or in short referred to as a grid). The introduction of the distributed generation has merit, because an electric power company purchases the inversely-flowing electric power by paying a predetermined unit price for it. 
     On the other hand, for example because the solar photovoltaic power generation varies in an amount of generated electric power according to an amount of insolation, a technology has been considered that accomplishes a stable supply of the electric power by charging an electricity accumulation apparatus, which is introduced, when the excessively-generated electric power occurs, and by discharging the electricity accumulation apparatus, conversely when the electric power is insufficient. 
     However, since also the electric power from the commercial power grid is stored in the electricity accumulation apparatus, it can not be determined whether the electric power stored in the electricity accumulation apparatus is the electric power from the solar photovoltaic power generation or is the electric power purchased from the commercial power grid. For this reason, as disclosed in JP-A-2007-209133, a technology is known in which the inverse load flow is possible with respect to the electric power generated by the solar battery, but the inverse load flow (a sale of the electric power) is prevented with respect to the electric power charged from the grid to the electricity accumulation apparatus. 
     CITATION LIST 
     Patent Literature 
     
         
         [PTL 1] JP-A-2007-209133 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the related art, since the inverse load flow (the sale of the electric power) is prevented with respect to the electric power from the grid charged in the electricity accumulation apparatus, the inverse load flow of the amount of generated electric power, which is charged, is not possible. For this reason, there occurs a problem in that the excessive electric power from a distributed source can not be put to effective use. 
     An object of the invention is to provide an apparatus for controlling an electricity accumulation apparatus, an electricity accumulation apparatus, and a method of charging and discharging an electricity accumulation apparatus, which are able to put an electric power generation from a distributed generation to effective use, in applying the electricity accumulation apparatus to the distributed generation such as a solar photovoltaic power generation. 
     Solution to Problem 
     In order to attain the object, the invention provides a configuration in which a distributed generation&#39;s share of an electric power, which is an electric power from the distributed generation, in an electric power stored in an electricity accumulation apparatus is computed to suppress the electric power discharged from the electricity accumulation apparatus to a grid to the distributed generation&#39;s share of an electric power, or to report a value of an electric power that is to inversely flow to the grid, as a value of the electric power that is suppressed to the distributed generation&#39;s share of the electric power. 
     Also, in order to attain the object, the invention provides a configuration provided with a charge and discharge control unit that controls charging and discharging of an electricity accumulation apparatus, a first charge terminal that connects to a distributed generation, installed to the side of a customer, a second charge terminal that is linked to a power grid, a first discharge terminal that is linked to the power grid, and a second discharge terminal that connects to an electric apparatus of the customer. 
     Advantageous Effects of Invention 
     According to the invention, an electric power generation from the distributed generation can be put to effective use in applying the electricity accumulation apparatus to the distributed generation such as the solar photovoltaic power generation. 
     Other objects, features and advantages of the invention can be apparent from the following descriptions of embodiments relating to the accompanying drawings, according to the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating a first embodiment according to the invention. 
         FIG. 2  illustrates one embodiment of a charge measurement device, a discharge measurement device, and a measurement value display device. 
         FIG. 3  illustrates one example of a display terminal device in a case of introducing a solar power generation system. 
         FIG. 4  is a flowchart illustrating charge and discharge control of an electricity accumulation apparatus. 
         FIG. 5  is a flow chart illustrating one example (distribution charge control) of the charge and discharge control. 
         FIG. 6  illustrates one embodiment (nighttime grid charge) of the charge and discharge control. 
         FIG. 7  is a block diagram illustrating a second embodiment according to the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments according to the invention is described below referring to the drawings. Moreover, the present embodiments are described that use a solar battery as a distributed generation (PV and a solar photovoltaic power generation system). 
     First Embodiment 
       FIG. 1  is a block diagram illustrating a first embodiment of the invention. A distributed generation supporting electricity accumulation apparatus  10  illustrated in  FIG. 1 , is installed in a customer&#39;s house that is linked to a power grid  107 , and includes a charge and discharge control apparatus  105  and a charge and discharge storage device  115 , and two charge terminals and two discharge terminals. The charge and discharge control apparatus  105  and the charge and discharge storage device  115 , and each discharge terminal and each charge terminal are connected to one another over a predetermined communication network. In a case of receiving a charge order  11 , the charge and discharge control apparatus  105  transmits the charge order  11  to a first charge terminal  101  and a second charge terminal  103 . In the same manner, in a case of receiving a discharge order  12 , the charge and discharge control apparatus  105  transmits the discharge order  12  to a first discharge terminal  102  and a second discharge terminal  104 . Of each charge terminal and each discharge terminal, the first charge terminal  101  is connected to a distributed generation (hereinafter referred to as a solar battery)  106  with a predetermined electric wire (an electric power cable), the first discharge terminal  102  and the second charge terminal  103  are linked to the power grid  107  with a predetermined electric wire, and the second discharge terminal  104  is connected to an electric apparatus  111  (including an electric machine and appliance, an electric communication machine and appliance and the like), possessed by a customer, with the electric wire, in the same manner. Moreover, in addition to the solar battery, the distributed generation  106  also may be, for example, a wind power generation and additionally may be a renewal energy type of electric power generation apparatus that is known as a nature type and an environment type. Moreover, the electric machine and appliance and the electric communication machine and appliance, which are possessed by the customer, are connected to one another over the predetermined communication network, and specification information on electric power consumption (a load) and on the electric machine and appliance and the electric communication machinery and appliance may be transmitted to and received from one another or transmitted to and received from the distributed generation supporting electricity accumulation apparatus  10  and the solar battery  106 . 
     A first charge measurement device  108  is installed between the first charge terminal  101  and the solar battery  106 . The first charge measurement device  108  measures a charge electric power, which is charged to the distributed generation supporting electricity accumulation apparatus  10  (hereinafter referred to as a first amount of charge), of an amount of generated electric power that is generated by the solar battery  106  (hereinafter referred to as an electric power generation). Data on the measured first amount of charge are transmitted to a measurement value display device  110  installed in the customer&#39;s house and to the charge and discharge control apparatus  105  within the distributed generation supporting electricity accumulation apparatus  10 . On the other hand, after flowing through the first charge measurement device  108 , the amount of charge is charged to the distributed generation supporting electricity accumulation apparatus  10  from the first charge terminal  101 . 
     In the same manner, a first discharge measurement device  109  and a first direct current and alternating current conversion apparatus  112  are installed between the first discharge terminal  102  and the power grid  107 . The first discharge measurement device  109  measures an electric power that inversely flows from the distributed generation supporting electricity accumulation apparatus  10  to the power grid  107  (hereinafter referred to as a first amount of discharge), and successively converts an electric power, which is discharged, from a direct current to an alternating current, in the first direct current and alternating current conversion apparatus  112 , and then causes the alternating-current-converted electric power to inversely flow to the power grid  107 . The electric power that inversely flows in this manner is measured or calculated in a measurement device not illustrated, and the electric power is reported to an electric power company. A purchase of the electric power is made based on this report. Data on the measured first amount of discharge are transmitted to the measurement value display device  110  installed within the customer&#39;s house and to the charge and discharge control apparatus  105  within the distributed generation supporting electricity accumulation apparatus  10 . 
     On the other hand, also the electric power that results from deducting the first amount of charge from the electric power generation that is generated by the solar battery  106  is converted from the direct current to the alternating current in the first direct current and alternating current conversion apparatus  112 , and then is caused to inversely flow to the power grid  107 . 
     With regard to an charge electric power that is charged to the distributed generation supporting electricity accumulation apparatus  10  from the power grid  107  (hereinafter referred to as a second amount of charge), the second amount of charge is converted from the alternating current into the direct current, in a second direct current/alternating current conversion apparatus  113  installed between the power grid  107  and the second charge terminal  103 , and then is charged to the distributed generation supporting electricity accumulation apparatus  10  from the second charge terminal  103 . An electric power, which is to be used in the predetermined electric apparatus  111  possessed by the customer (hereinafter referred to as a second amount of discharge), of an charge electric power that is charged to the distributed generation supporting electricity accumulation apparatus  10  (the first amount of charge+the second amount of charge) is discharged from the second discharge terminal  104 , and then is converted from the direct current to the alternating current in the second direct current and alternating current conversion apparatus  113  and is consumed in the electric apparatus  111 . On the other hand, also with regard to the electric power that is purchased from the power grid  107  (an amount of purchased electric power), the remainder of the electric power that results from excluding the second amount of charge is assigned to the electric apparatus  111 , thereby leading to consumption by the electric apparatus  111 . As a result, the customer can use the electric apparatus  111 . 
     Moreover, measurement data on the first amount of charge and the second amount of charge and measurement data on the first amount of discharge and the second amount of discharge, which are transmitted to the charge and discharge control apparatus  105 , are stored in the charge and discharge storage device  115 . The charge and discharge storage device  115  uses one of recordable mediums such as a HDD, a CD-RAM, a DVD-RAM, a flash memory and a Blue-Ray. 
     Furthermore, data communication between the first charge measurement device  108  and the first discharge measurement device  109 , and between the measurement value display device  110  and the charge and discharge control apparatus  105  is performed over the predetermined communication network, and the communication network is for wired communication or wireless communication such as ADSL or optical communication. In addition to a dedicated terminal monitor, a PC display, a television, or a mobile device such as a mobile phone, may be used as the measurement value display device  110 . 
     Next, basic configurations of the first charge measurement device  108  and the first discharge measurement device  109  are described referring to  FIG. 2 .  FIG. 2  is a block diagram illustrating the basic configurations of the first charge measurement device  108  and the first discharge measurement device  109 . 
     The first charge measurement device  108  is configured to include an amount-of-charge measurement device  201 , an amount-of-charge storage device  202 , and an amount-of-charge transmission device  203 , and measures a first amount of charge  210  in a case where the electric power (the first amount of charge)  210 , charged to the distributed generation supporting electricity accumulation apparatus  10 , in the electric power generation that is generated by the solar battery  106 , flows through the amount-of-charge measurement device  201 . Measurement data (numerical values) on the measured first amount of charge  210  are transmitted to the amount-of-charge storage device  202  and the amount-of-charge transmission device  203 . The amount-of-charge storage device  202  receives and stores the measurement data on the first amount of charge  210 . The amount-of-charge transmission device  203  transmits the measurement data on the first amount of charge to the measurement value display device  110  installed within the customer&#39;s house, and the measurement data on the first amount of charge  210  is received by a measurement value reception device  207  of the measurement value display device  110 . 
     The first discharge measurement device  109  is configured to include an amount-of-discharge measurement device  204 , an amount-of-discharge transmission device  205 , and an amount-of-discharge storage device  206 , and measures a first amount of discharge  211  in a case where the first amount of charge  211 , discharged from the distributed generation supporting electricity accumulation apparatus  10 , flows through the amount-of-discharge measurement device  204 . The measurement data (numerical values) on the measured first amount of discharge are transmitted to the amount-of-discharge storage device  206  and the amount-of-discharge transmission device  205 . The amount-of-discharge storage device  206  receives and stores the measurement data on the first amount of discharge  211 . The amount-of-discharge transmission device  205  transmits the measurement data on the first amount of discharge  211  to the measurement value display device  110  installed within the customer&#39;s house, and the measurement data on the first amount of discharge is received by the measurement value reception device  207  of the measurement value display device  110 . 
     The measurement value display device  110  is configured to include the measurement value reception device  207 , a display device  208  and a measurement value storage device  209 , transmits the measurement data on the first amount of charge  210  and the measurement data on the first amount of discharge  211 , which are received by the measurement value reception device  207 , to the display device  208 , and displays the measurement data on the display device  208 . Moreover, in addition to the dedicated terminal monitor, the PC display, the television, or the mobile device such as the mobile phone, may be used as the display device  208 . The measurement value storage device  209  stores the measurement data on the first amount of charge  210  and the measurement data on the first amount of discharge  211 . The amount-of-charge storage device  202 , the amount-of-discharge storage device  206  and the measurement value storage device  209  use one of the recordable mediums such as the HDD, the CD-RAM, the DVD-RAM, the flash memory and the Blue-Ray. Furthermore, the amount-of-charge storage device  202  and the amount-of-discharge storage device  206 , and the measurement value storage device  209  are smaller in storage capacity than the charge and discharge storage device  115 , and removes the numerical values, beginning with the numerical value from the storage of which 24 hours have elapsed. 
     Next,  FIG. 3  illustrates the measurement value display device  110  according to one embodiment in a case where the distributed generation supporting electricity accumulation apparatus  10  connects to the solar battery  106 . The customer who introduces the distributed generation supporting electricity accumulation apparatus and an electric power storage system according to the invention can install the measurement value display device  110  within the customer&#39;s house and can grasp the amount of charge and the amount of discharge in the distributed generation supporting electricity accumulation apparatus  10 . 
     A display screen  301  is configured to include a display space  302  on which to display an amount of charge [Ah] in the distributed generation supporting electricity accumulation apparatus  10  as a diagram, a display space  303  on which to display the amount of charge as a numerical value, a display space  304  which displays a ratio [%] of one part of the electric power generation in the solar battery  106  to the full capacity of the first amount of charge that is charged and the numerical value (an absolute amount) [Ah], and a display space  305  which displays the ratio [%] of one part of the amount of purchased electric power in the power grid  107  to the full capacity of the second amount of charge that is charged and the numerical value (the absolute amount) [Ah]. 
     On the display space  302 , the amount [Ah] of charged electric power in the distributed generation supporting electricity accumulation apparatus  10  is displayed as bar graphs ( 306 ,  307 , and  308 ). The bar graph  306  displays an electric power that can be currently charged, the bar graph  307  displays the ratio [%] of the first amount of charge, and the bar graph  308  displays the ratio [%] of the second amount of charge. Moreover, according to the present embodiment, each amount of charge is displayed as the ratio [%], but may be displayed as the absolute amount [Ah] and the display may arbitrarily be changed by the customer. Furthermore, in addition to [Ah], each amount of charge may also be displayed as [kWh]. 
     As a method for displaying on the display screen  301 , the display method may arbitrarily be changed by the customer. In a case of a display screen  314 , the first amount of charge (indicated by a solid line  310 ) that is charged from the electric power generation in the solar battery  106  is shown on a graph  309  with the electric current [A] resulting from charging along the vertical axis and time [h] along the horizontal axis. An electric current value [A] of the electric power that is charged from the current time solar battery  106  and the amount of charge [Ah] from a predetermined time are shown as numbers on a display space  311 . In the same manner, in a case of a display screen  315 , the second amount of charge (indicated by a solid line  312 ) is shown on the same graph  309 , based on the amount of purchased electric power from the power grid  107 . The electric current value [A] of the electric power that is charged from the current time solar battery  107  and an accumulated amount of charge [Ah] from the predetermined time are shown as numbers on a display space  313 . Moreover, in addition to [Ah], a unit of the amount of charge may be shown as [kWh]. 
     Next, charge and discharge control of the distributed generation supporting electricity accumulation apparatus  10  is described using  FIG. 4 .  FIG. 4  is a flowchart illustrating processing details of the charge and discharge control according to one embodiment of the invention. 
     In processing S 401 , a use-permissible range Rc [Ah] (a use-permissible lower limit value R L  [A] and a use-permissible upper limit value R H  [A]) is read within which the distributed generation supporting electricity accumulation apparatus can be used, and proceeding to processing S 402  takes place. In the processing S 402 , the charge order  11  (CH_ORDER) is read, and the proceeding to processing S 403  takes place. In the processing S 403 , the discharge order  12  (DCH_ORDER) is read, and the proceeding to processing S 404  takes place. Moreover, as the charge order  11  and the discharge order  12 , for example, in addition to the charge order and the discharge order from the customer, in whose customer&#39;s house the distributed generation supporting electricity accumulation apparatus is installed, the charge order and the discharge order may be possible from a manager, responsible for the power grid, and the charge order and the discharge order associated with the charge and discharge control may be possible such as feedback control and feedforward control of the corresponding distributed generation supporting electricity accumulation apparatus. Next, in processing S 404 , a current state of charge (SOC) Sc [Ah] is read, and the proceeding to processing S 405  takes place. In the processing S 405 , it is determined whether or not charging and discharging are possible, based on formulas (1), (2), and (3), from SOC read in the processing S 404 , the use-permissible range Rc read in the processing S 401 , and a rated capacity C N  [Ah] of the distributed generation supporting electricity accumulation apparatus. 
         C   N   ×R   L   &lt;Sc&lt;C   N   ×R   H   (1)
 
       ( i ) Sc&lt;C   N   ×R   H : charging is possible  (2)
 
       ( ii ) C   N   ×R   L   &lt;Sc : discharging is possible  (3)-1
 
       ( iii )0 &lt;Sc ( pv )discharging is possible  (3)-2
 
     In the processing S 405 , in a case where a charging-possible condition expressed by the formula (2) is met, it is determined that the charging is possible and the proceeding to processing S 406  takes place. In the processing S 406 , a charging-possible flag is set to ON (fCHarge_ABLE=1) and the electricity accumulation apparatus  10  is set to a charging-possible state. Next, in processing S 407 , the charging starts and then the proceeding to processing S 408  takes place. Moreover, in a case where the electric power, generated by the charging in the distributed generation, is charged through the first charge terminal  101 , a charge start signal is output to the first charge measurement device  108 , and the first charge measurement device  108  measures an amount of charge Cp [Ah]. 
     Next, in the processing S 408 , the amount of charge Cp measured by the first charge measurement device  108  is read by the charge and discharge control apparatus  105 , and the proceeding to processing S 409  takes place. In the processing  5409 , the amount of charge Cp is stored by the charge and discharge storage device  115 , and returning to the processing  405  takes place. Moreover, in a case where the electric power from the power grid  107  is charged through the second charge terminal  103  to which the charge measurement device is not attached, the returning to the processing S 405  takes place without performing the processing S 408  and the processing S 409  (a flow indicated by a dotted line). 
     On the other hand, in the processing S 405 , in a case where a discharging-possible condition expressed by both of the two formulas, the formulas (3)-1 and (3)-2, is met, it is determined that the discharging is possible, and the proceeding to processing S 413  takes place. At this point, Sc (pv) is a solar battery&#39;s share of the electric power generation in the state of charge (SOC) Sc, and is a difference (ΣCp−ΣDp) between an accumulately-computed value (ΣCp) of the amounts of charge Cp [Ah] in the first charge measurement device  108  and the accumulately-computed value (ΣDp) of the amounts of discharge Dp [Ah] in the first discharge measurement device  109 . The corresponding accumulately-computed value is computed at a predetermined period and is stored in the charge and discharge storage device  115 . 
     The formula (3)-2 shows that the solar battery  106 &#39;s share of the electric power generation in the state of charge (SOC) is zero or more. That is, in a case where the electric power generation (the accumulately-computed value) in the solar battery  106  is greater than the amount of discharge (the accumulately-computed value) to the commercial power grid  107 , the discharging to the power grid to the extent exceeding this is not performed. 
     Moreover, the condition expressed by the formula (3)-2 can be excluded. That is, the electric power, greater than the electric power generation in the solar battery  106  can be discharged to the commercial power grid  107 . However, in this case, the electric power that is a target for the charging is defined as an upper limit on the electric power generation in the solar battery  106 . This computation is performed by the charge and discharge control apparatus  105  and is reported to the electric power company. 
     In the processing S 413 , a discharging-possible flag is set to ON (fDCHARGE_ABLE=1) and the electricity accumulation apparatus  10  is set to a discharging-possible state. Next, in processing S 414 , the discharging starts, and then the proceeding to processing S 415  takes place. Moreover, in a case where the discharging is discharged from the first discharge terminal  102  that is connected to the first discharge measurement device  109 , a discharge start signal is output to the first discharge measurement device  109 , and the first discharge measurement device  109  measures the amount of discharge Dp [Ah]. Next, in the processing S 415 , the amount of discharge Dp measured by the first discharge measurement device  109  is read by the charge and discharge control apparatus  115 , and the proceeding to processing S 416  takes place. In the processing S 416 , the amount of discharge Dp is stored in the charge and discharge storage device  115 , and the proceeding to processing S 417  takes place. Moreover, in a case where the electric power discharged to an electric apparatus installed in the customer&#39;s house is consumed from the second discharge terminal  104  to which the discharge measurement device is not attached, the returning to the processing S 405  takes place without performing the processing S 415  and the processing S 416  (a flow indicated by a dotted line). 
     Next, in the processing S 417 , it is determined whether or not the discharging ends using the formula (4), based on the charging state Sc read in the processing S 404 , the amount of charge Cp read in the processing S 408 , and the amount of discharge Dp read in the processing S 415 . 
       ( Sc+Cp )− Dp≦C   N   ×R   L   (4)
 
     In the processing S 417 , in a case where the condition for determining the ending of the discharging, expressed by the formula (4), is met, the proceeding to processing S 418  takes place. In the processing S 418 , the discharging-possible flag is set to OFF (fDCHARGE_ABLE=0). Next, in processing S 419 , a discharging stop signal is output to the charge and discharge control apparatus  105  and discharge control is ended. In the processing S 417 , in a case where the condition for determining the ending of the discharging, expressed by the formula (4), is not met, it is determined that the continuous discharging is possible, and that returning to the processing S 414  takes place to perform the continuous discharging. 
     On the other hand, in the processing S 405 , in a case where the charging-possible condition, expressed by the formula (2), is not met, it is determined that the electric power can not be charged to the distributed generation supporting electricity accumulation apparatus, and the proceeding to the processing S 410 . In the processing S 410 , the charging-possible flag is set to OFF (fCHARGE_ABLE=0). Next, in processing S 411 , a charging stop signal is output to the charge and discharge control apparatus  105  and thus charge control is ended and the proceeding to processing S 412  takes place. In the processing S 412 , the discharge order is checked again, and in a case where the discharge order  12  is not present, or is cancelled (DCH_ORDER=0), the charge and discharge control is ended. In the processing S 412 , in a case where the discharge order  12  is present (DCH_ORDER=1), the proceeding to processing S 413  takes place, and the discharging control is performed based on the discharge control flow. 
     Moreover, in the processing S 405 , in a case where the formula (2) and the formula (3) are both valid, the processing S 406  to the processing S 409 , and the processing S 413  to the processing to S 419  can be performed at the same time in terms of time, and in such a case the discharging is performed while the charging is performed. In addition to Ah (ampere hour), the unit of the electric power that is charged and discharged may be in kWh (kilowatt hour). 
     Next, the charge and discharge control of the distributed generation supporting electricity accumulation apparatus  10  is described using  FIG. 5 .  FIG. 5  is a flowchart illustrating the processing details of charge and discharge distribution control according to one embodiment of the invention. In processing S 501 , the use-permissible range Rc [Ah] (the use-permissible lower limit value R L  [%] and the use-permissible upper limit value R H  [%]) is read within which the distributed generation supporting electricity accumulation apparatus can be used, and the proceeding to processing S 502  takes place. In the processing S 502 , the charge order (CH_ORDER) is read, and the proceeding to processing S 503  takes place. In the processing S 503 , time (T_HOUR) is read, and the proceeding to processing S 504  takes place. Moreover, the time (T_HOUR) is in 24 hours units (every hour from 0 to 23). Next, in the processing S 504 , the current state of charge (SOC) Sc [Ah] is read, and the proceeding to processing S 505  takes place. In the processing S 505 , a charge distribution rate cDST_PV indicating a ratio of the electric power [Ah] that is charged from the distributed generation (hereinafter referred to as the solar battery) and a charge distribution rate cDST_GR indicating the ratio of the electric power [Ah] that is charged from the power grid are read, and the proceeding to processing S 506  takes place. In the processing S 506 , it is determined whether or not it is daytime, using a formula (5), based on the time T_HOUR and real time that are read in the processing S 503 . Furthermore, it is determined whether or not the charging from the solar battery is possible, using a formula (6), based on the use-permissible range Rc and the rated capacity C N  that are read in the processing S 501  and on the state of charge (SOC) Sc that is read in the processing S 504 . In the same manner, it is determined from the formula (6)′ whether or not the charging from the power grid is possible. 
         cT   —   AM≦T _HOUR≦ cT   —   PM   (5)
 
         Cpv&lt;Cap   (6)
 
         Cgr&lt;Cag   (6)′
 
     In the formulas, cT_AM represents a daytime start threshold value, cT_PM represents a nightime start threshold value, and time is represented with 24 hour units (with numbers every hour from 0 to 23). Furthermore, Cpv is the amount of charge [Ah] from the solar battery, and is a measurement value measured by the first charge measurement device  108 , and Cap is the possible amount of charge [Ah] that is the solar battery&#39;s share and is computed using a formula (7). Cgr is the amount of charge [Ah] from the power grid and is computed using a formula (8) when the amount of charge after the charging start is defined as Sc′, and Cag is the possible amount of charge [Ah] from the power grid and is computed using a formula (9). 
         Cap=Cabl×cDST   —   PV   (7)
 
         Cgr=Sc ′−( Cpv+Sc )  (8)
 
         Cag=Cabl×cDST   —   GR   (9)
 
     In the formulas, Cabl is the possible amount of charge [Ah] and is computed using a formula (10). 
         Cabl=C max− Sc   (10)
 
     Cmax is a charging-possible upper limit value [Ah] and is computed using a formula (11). 
         C max= C   N   ×R   H   (11)
 
     In a case where the amount of generated electric power generated by the solar battery is charged, when the formulas (5) and the formula (6) are valid at the same time in the processing S 506 , it is determined that the amount of generated electric power generated by the solar battery can be charged and the proceeding to processing S 507  takes place. In the processing S 507 , a flag indicating that the charging is possible from the solar battery is set to ON (fCHARGE_ABLE_PV=1). Furthermore, with regard to the charging from the power grid, in a case where the formula (6)′ is valid in the processing S 506 , it is determined that the electric power from the power grid can be charged and the proceeding to the processing S 07  takes place. In the processing S 507 , a flag indicating that the charging is possible from the power grid is set to ON (fCHARGE_ABLE_GR=1). 
     Next, in processing S 508 , the charging starts and then the proceeding to processing S 509  takes place. Moreover, in a case where the amount of generated electric power, generated by the solar battery, is charged from the first charge terminal  101  to the electricity accumulation apparatus  10 , the charge start signal is output to the first charge measurement device  108 , and the first charge measurement device  108  measures an amount of charge Cpv [Ah]. 
     Next, in the processing S 509 , the amount of charge Cpv measured by the first charge measurement device  108  is read by the charge and discharge control apparatus  105 , and the proceeding to processing S 510  takes place. In the processing S 510 , the amount of charge Cpv is stored by the charge and discharge storage device  115 , and the returning to the processing S 506  takes place. Moreover, in a case where the electric power from the power grid  107  is charged through the second charge terminal  103  to which the charge measurement device is not attached, the returning to the processing S 506  takes place without performing the processing S 509  and the processing S 510  (a flow indicated by a dotted line). 
     On the other hand, in a case where the amount of generated electric power generated by the solar battery is charged, when either of the formula (5) and the formula (6) is not valid in the processing S 506 , it is determined that the amount of generated electric power generated by the solar battery is not charged and the proceeding to processing S 511  takes place. In the processing S 511 , the flag indicating that the charging is possible from the solar battery is set to OFF (fCHARGE_ABLE_PV=0). Next, in processing S 512 , the charging from the solar battery is stopped and charge distribution control is ended. Furthermore, in the same manner with regard to the charging from the power grid, in a case where the formula (6)′ is not valid in the processing S 506 , it is also determined that the electric power from the power grid is not charged and the proceeding to the processing S 11  takes place. In the processing S 511 , the flag indicating that the charging is possible from the power grid is set to OFF (fCHARGE_ABLE_GR=0). Next, in processing S 512 , the charging from the power grid is stopped and charge distribution control is ended. 
     Next, one embodiment of the charge and discharge control of the distributed generation supporting electricity accumulation apparatus  10  (hereinafter referred to as the electricity accumulation apparatus) is described using  FIG. 6 .  FIG. 6  illustrates the embodiment of a method of controlling charging and discharging in a case where the electric power from the power grid (nighttime electric power) that is charged to the electricity accumulation apparatus  10  in the night is assigned to an electric load that is consumed by the customer in the daytime, and on the other hand the electric power generated by the distributed generation inversely flows to the power grid  107  (a sale of the electricity). 
     A graph  601  is a graph that represents the electric power [kW], which is charged from the power grid  107 , along the vertical axis, and the time [h] along the horizontal axis. A time zone  604  is a daytime zone (hereinafter referred to as daytime), and according to the present embodiment, 10 hours from 8:00 a.m to 18:00 p.m is defined as daytime. With regard to the setting of the daytime, the customer, or a manager responsible for the power grid, an enterpriser responsible for the electric power generation, or a manager responsible for the distributed generation arbitrarily sets the daytime in advance, or can set it to the time zone that is determined in advance seasonally or monthly. A graph  602  is a graph that represents the electric power [kW] generated by the solar battery (the distributed generation)  106  along the vertical axis, and the time [h] along the horizontal axis. A graph  603  is a graph that represents that the electric power [kW] consumed over time (hereinafter referred to as the electric power load) in the customer&#39;s house in which the corresponding electricity accumulation apparatus  10  is installed, along the vertical axis, and the time [h] along the horizontal axis. 
     As illustrated in the graph  601 , first, the electric power from the power grid  107  is charged from 18:00 to 23:00 that is a nighttime zone (hereinafter referred to as nighttime) on the predetermined day (hereinafter referred to as the x-th day) and from 00:00 to 08:00 that is a time zone on the next day, that is, on the (x+1)-th day ( 605 ). An amount of charge Cgr [kWh] is the sum of the electric power  605  charged from 18:00 to 23:00 on the x-th day and the electric power  605  charged from 00:00 to 08:00 on the (x+1)-th day. The state of charge (SOC) of the electricity accumulation apparatus  10  at 8:00 on the (x+1)-th day becomes a state of charge  607  in which the corresponding amount of charge Cgr [kWh] is charged with respect to a maximum permissible amount  606  (a dotted line frame). 
     Next, when the solar battery  106  generates the electric power in a pattern of an electric power generation curved line  608  after 8:00 on the (x+1)-th day, the amount of generated electric power Gpv[kWh], a portion that is computed with time integration of the electric power generation curved line  608 , is entirely caused to inversely flow to the power grid  107  in order to sell the electricity. 
     On the other hand, as illustrated in the graph  603 , when the power consumption (hereinafter referred to as a load pattern) by the customer on the (x+1)-th day is on a curved line  609 , an electric power Cgr  605  charged to the electricity accumulation apparatus  10  is discharged with respect to the daytime load pattern in such a manner as to follow the corresponding load pattern  609 . An amount of discharge Dp [kWh]  610  is computed with the time integration of the discharged electric power [kW]. Because at that time the basic discharge control gives priority to the discharging over the daytime  604 , a maximum value  611  [kW] of the amount of discharge is set according to the state of charge (SOC)  607  at 8:00 on the (x+1)-th day and the time zone [h], which is the daytime  604 , and the electric power from the power grid  107  is assigned with respect to the load [kW] in the time zone in which the load pattern  609  exceeds the maximum value  611  [kW] of the amount of discharge (selling the electricity). 
     The state of charge (SOC) of the electricity accumulation apparatus  10  at 18:00 on the (x+1)-th day after the discharging becomes a state of charge  612  [kWh] that results from deducting the amount of discharge Dp [KWh] from the state of charge  607 . 
     Moreover, the maximum value  611  of the amount of discharge may not be set, and in such a case, the discharge control gives priority to the discharging that follows the load pattern  609 , without giving priority to the discharging over the entire time zone of the daytime  604 . For this reason, in a case where the electric power Cgr in the state of charge  607  is fully discharged in the middle of the daytime  604 , the control may also be performed in such a manner that the discharge control is ended in the middle, and the electric power from the power grid  107  is assigned with respect to an electric apparatus. 
     Second Embodiment 
       FIG. 7  is a block diagram illustrating a second embodiment of the invention. A distributed generation supporting electricity accumulation apparatus  70  illustrated in  FIG. 7 , is installed in a customer&#39;s house that is linked to a power grid  707 , and includes a charge and discharge control apparatus  705  and a charge and discharge storage device  715 , and two charge terminals and two discharge terminals, and a first charge measurement device  708  and a first discharge measurement device  709 . 
     The charge and discharge storage device  705  and the charge and discharge storage device  715 , and each charge terminal and each discharge terminal, and further the first charge measurement device  708 , the first discharge measurement device  709 , and a measurement value display device  710  are connected to one another over a predetermined communication network. In a case of receiving a charge order  71 , the charge and discharge control apparatus  705  transmits the charge order  71  to a first charge terminal  701  and a second charge terminal  703 . In the same manner, in a case of receiving a discharge order  12 , the charge and discharge control apparatus  705  transmits the discharge order  72  to a first discharge terminal  702  and a second discharge terminal  704 . Of each charge terminal and each discharge terminal, the first charge terminal  701  is connected to a distributed generation (hereinafter referred to as a solar battery)  706  with a predetermined electric wire (an electric power cable), the first discharge terminal  702  and the second charge terminal  703  are linked to the power grid  707  with a predetermined electric wire, and the second discharge terminal  704  is connected to an electric apparatus  711  (including an electric machine and appliance, an electric communication machinery and appliance and the like), possessed by a customer, with the electric wire, in the same manner. Moreover, the electric machine and appliance and the electric communication machinery and appliance, which are possessed by the customer, are connected to one another over the predetermined communication network, and specification information on electric power consumption (a load) and on the electric machine and appliance and the electric communication machinery and appliance may be transmitted to and received from one another or transmitted to and received from the distributed generation supporting electricity accumulation apparatus  70  and the solar battery  706 . 
     The first charge measurement device  708  is connected between the first charge terminal  701  and the solar battery  706  with a predetermined electric power cable. The first charge measurement device  708  measures an amount of charge, which is charged to the distributed generation supporting electricity accumulation apparatus  70  (hereinafter referred to as a first amount of charge), of an amount of generated electric power that is generated by the solar battery  706  (hereinafter referred to as an electric power generation). Data on the measured first amount of charge are transmitted to a measurement value display device  710  installed in the customer&#39;s house and to the charge and discharge control apparatus  705  within the distributed generation supporting electricity accumulation apparatus  70 . On the other hand, after flowing through the first charge measurement device  708 , the amount of charge is charged to the distributed generation supporting electricity accumulation apparatus  70  from the first charge terminal  701 . 
     In the same manner, the first discharge measurement device  709  and a first direct current and alternating current conversion apparatus  712  are connected between the first discharge terminal  702  and the power grid  707  with a predetermined electric power cable. The first discharge measurement device  709  measures an electric power that inversely flows from the distributed generation supporting electricity accumulation apparatus  70  to the power grid  707  (hereinafter referred to as a first amount of discharge), and successively converts an electric power, which is discharged, from a direct current to an alternating current, in the first direct current and alternating current conversion apparatus  712 , and then causes the alternating-current-converted electric power to inversely flow to the power grid  707 . Data on the measured first amount of discharge are transmitted to the measurement value display device  710  installed within the customer&#39;s house and to the charge and discharge control apparatus  705  within the distributed generation supporting electricity accumulation apparatus  70 . 
     On the other hand, also the electric power that results from deducting the first amount of charge from the electric power generation that is generated by the solar battery  706  is converted from the direct current to the alternating current in the first direct current and alternating current conversion apparatus  712 , and then is caused to inversely flow to the power grid  707 . 
     With regard to an amount of charge that is charged to the distributed generation supporting electricity accumulation apparatus  70  from the power grid  707  (hereinafter referred to as a second of charge), the second amount of charge is converted from the alternating current into the direct current, in a second direct current and alternating current conversion apparatus  713  installed and connected with a predetermined electric power cable between the power grid  707  and the second charge terminal  703 , and then is charged to the distributed generation supporting electricity accumulation apparatus  70  from the second charge terminal  703 . An electric power, which is to be used in the predetermined electrical apparatus  711  possessed by the customer (hereinafter referred to as a second amount of discharge), of an amount of charge that is charged to the distributed generation supporting electricity accumulation apparatus  70  (the first amount of charge+the second amount of charge) is discharged from the second discharge terminal  704 , and then is converted from the direct current to the alternating current in the second direct current and alternating current conversion apparatus  713  and is consumed in the electrical apparatus  711 . On the other hand, also with regard to the electric power that is purchased from the power grid  707  (an amount of purchased electric power), the remainder of the electric power that results from excluding the second amount of charge is assigned to the electric apparatus  711 , thereby leading to consumption by the electric apparatus  711 . As a result, the customer can use the electric apparatus  711 . 
     Moreover, the measurement data on the first amount of charge and the second amount of charge and the measurement data on the first amount of discharge and the second amount of discharge, which are transmitted to the charge and discharge control apparatus  705 , are stored in the charge and discharge storage device  715 . The charge and discharge storage device  715  uses one of the recordable mediums such as the HDD, the CD-RAM, the DVD-RAM, the flash memory and the Blue-Ray. 
     Furthermore, the data communication between the first charge measurement device  708  and the first discharge measurement device  709 , and between the measurement value display device  710  and the charge and discharge control apparatus  705  is performed over the predetermined communication network, and the communication network is for wired communication or wireless communication such as ADSL or optical communication. In addition to the dedicated terminal monitor, the PC display, the television, or the mobile device such as the mobile phone, may be used as the measurement value display device  710 . 
     Features of the above embodiments are again described as follows. The electricity accumulation apparatus that is installed to the side of a customer includes a charge and discharge control unit that controls charging and discharging of the electricity accumulation apparatus, a first charge terminal that connects to a distributed generation, installed to the side of the customer, a second charge terminal that is linked to a power grid, a first discharge terminal that is linked to the power grid, and a second discharge terminal that connects to an electric apparatus of the customer (feature  1 ). 
     The electricity accumulation apparatus includes a first charge measurement device between the distributed generation and the first charge terminal, and a first discharge measurement device between the power grid and the first discharge terminal. The first charge measurement device includes an amount-of-charge measurement unit that measures an electric power (an amount of charge), charged to the electricity accumulation apparatus, in an amount of generated electric power generated by the distributed generation. The first discharge measurement device includes a discharge measurement unit that measures an electric power (an amount of discharge) that is discharged from the electricity accumulation apparatus (feature  2 ). 
     The first charge measurement device includes an amount-of-charge transmission unit that transmits numerical data on the measured amount of charge to a measurement value display device and the charge and discharge control unit, and the first discharge measurement device includes an amount-of-discharge transmission unit that transmits the numerical data on the measured amount of discharge to the measurement value display device and the charge and discharge control unit (feature  3 ). 
     An electric power (an amount of charge) that is charged to the electricity accumulation apparatus from an amount of generated electric power generated by the distributed generation is measured by the first charge measurement device, and then is charged to the electricity accumulation apparatus through the first charge terminal, and a second direct current and alternating current conversion apparatus converts the electric power from the power grid from alternating current electric power to direct current electric power, and then direct-current-electric-power converted electric power is charged to the electricity accumulation apparatus through the second charge terminal (feature  4 ). 
     A distinction is made between an electric power charged from the distributed generation and an electric power charged from the power grid, in an electric power charged to the electricity accumulation apparatus, based on the numerical data on the amount of charge measured by the first charge measurement device (feature  5 ). 
     There is a feature that the electric power, charged from the distributed generation, in the electric power charged to the electricity accumulation apparatus, is discharged from the first discharge terminal, the electric power discharged (the amount of discharge) is measured in the first discharge measurement device, then the first direct current and alternating current conversion apparatus converts the measured amount of discharge from the direct current electric power to the alternating current electric power, and the alternating-current-electric-power converted electric power is discharged to the power grid (an inverse flow) (feature  6 ). 
     The electric power, charged from the power grid, in the electric power charged to the electricity accumulation apparatus is discharged from the second discharge terminal, the electric power discharged is converted from the alternating current electric power to the direct current electric power in the second direct current and alternating current conversion apparatus, and then the direct-current-electric-power converted electric power is consumed in an electric apparatus possessed by the customer (feature  7 ). 
     With respect to an amount of generated electric power generated by the distributed generation, the amount of generated electric power is converted by the first direct current and alternating current conversion apparatus from the direct current electric power to the alternating current electric power, and then alternating-current-electric-power converted electric power is caused to inversely flow to the power grid. At the same time, the electric power, which is charged to the electricity accumulation apparatus, and which is charged from the distributed generation, is discharged from the first discharge terminal to the power grid. As a result, the electric power that is equal to or more than an electric power that is generated by the distributed generation is caused to inversely flow to the power grid (feature  8 ). 
     The electricity accumulation apparatus includes a measurement value reception unit that receives numerical data on an amount of charge which is transmitted from the first charge measurement device and numerical data on an amount of discharge which is transmitted from the first discharge measurement device, a measurement value storage unit that stores the numerical data on the amount of charge and the numerical data on the amount of discharge, and a measurement value display unit that displays the numerical data. The numerical data on the amount of charge measured by the first charge measurement device and the numerical data on the amount of discharge measured by the first discharge measurement device are displayed (feature  9 ). 
     The distributed generation is an electric power generation apparatus, installed to the side of the customer and includes at least one or more electric power generation system of a solar photovoltaic power generation system using solar cells, a wind power generation system, a co-generation system including a generator using gas, and a bio-mass generation system (feature  10 ). 
     The electric apparatus is an apparatus, possessed by the customer, which consumes the electric power. The electric apparatus includes at least one or more of an electric machine and appliance, an electric communication machine and appliance, an electronic applied machine and appliance, and a medical machine and appliance (feature  11 ). 
     A distinction is made between an electric power charged from the distributed generation and an electric power charged from the power grid, in an electric power charged to the electricity accumulation apparatus, based on the numerical data on the amount of charge measured by the first charge measurement device, and only the electric power charged from the distributed generation, or only the electric power generated by the distributed generation is caused to inversely flow to the power grid (feature  12 ). 
     According to the features  1  to  12  described above, it is possible to grasp the amount of generated electric power, generated by the distributed generation, which is charged to the electricity accumulation apparatus, by including the charge terminal that connects to the distributed generation, the discharge terminal that connects to a power grid, the charge terminal that connects to the power grid, and the discharge terminal for discharging to an electric power load such as the electric apparatus and by attaching an electric power meter to the charge terminal and the discharge terminal that connect to the distributed generation. Therefore, it is possible to make a distinction of the distributed generation&#39;s share of the amount of generated electric power, which comes from the distributed generation, in the electric power that is charged to the electricity accumulation apparatus and to cause the amount of generated electric power to inversely flow to the power grid (a sale of the electricity). 
     The above descriptions are provided with regard to the embodiments, but the invention is not limited to this, and it is apparent to a person of ordinary skill in the art that various modifications and changes are possible within the nature of the invention and the scopes of the accompanying claims. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10  DISTRIBUTED GENERATION SUPPORTING ELECTRICITY ACCUMULATION APPARATUS 
               106  DISTRIBUTED GENERATION (SOLAR BATTERY) 
               107  COMMERCIAL POWER GRID (POWER GRID) 
               111 , 711  ELECTRIC APPARATUS (ELECTRIC APPARATUS POSSESSED BY CUSTOMER) 
               301  DISPLAY SCREEN (MEASUREMNET VALUE DISPLAY SCREEN) 
               604  DAYTIME TIME ZONE (DAYTIME) 
               605  AMOUNT OF CHARGE [kWh] FROM POWER GRID 
               606  MAXIMUM AMOUNT (CAPACITY) OF CHARGE FOR ELECTRICITY ACCUMULATION APPARATUS 
               607  STATE OF CHARGE OF ELECTRICITY ACCUMULATION APPARATUS AFTER BEING CHARGED FROM POWER GRID 
               608  ELECTRIC POWER [kWh] GENERATED BY SOLAR BATTERY 
               609  LOAD PATTERN OF CUSTOMER 
               610  AMOUNT OF DISCHARGE [kWH] FROM ELECTRICITY ACCUMULATION APPARATUS