Patent Publication Number: US-2016241072-A1

Title: Charge/discharge control device and program

Description:
TECHNICAL FIELD 
     The present invention relates to a charge/discharge control device and a program. 
     BACKGROUND ART 
     For example, there has been known a charge/discharge device configured to control charge and discharge of a storage battery (for example, Patent Literature 1). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2011-244682 
     SUMMARY OF INVENTION 
     Technical Problem 
     For example, a charge/discharge device in Patent Literature 1 controls charge and discharge of the storage battery based on the result of comparison between a selling price and a reference price of electric power. Such control of charge and discharge by the charge/discharge device does not consider an economic benefit of a consumer who owns the charge/discharge device. Thus, when the storage battery is charged/discharge by this charge/discharge device, the economic benefit by virtue of charging/discharging the storage battery may not be provided. 
     SUMMARY OF INVENTION 
     Solution to Problem 
     In order to solve the above-described problems, a primary aspect of the invention is directed to a charge/discharge control device configured to control charge and discharge of a storage battery in a consumer, the consumer including an electric power load, a distributed power supply, and the storage battery, the distributed power supply being configured to supply the electric power load with electric power, the storage battery being coupled to the electric power load and the distributed power supply, the charge/discharge control device including: a first determining device configured to determine whether an amount of power generation of the distributed power supply is larger than an amount of power consumption of the electric power load; and a first control device configured to, when the first determining device determines that the amount of power generation is larger than the amount of power consumption, control charge and discharge of the storage battery so that an economic benefit is brought to the consumer by control of the storage battery. 
     Other features of the present invention will become apparent from descriptions of the accompanying drawings and of the present specification. 
     Advantageous Effects of Invention 
     According to the present invention, charge and discharge of a storage battery can be controlled to bring an economic benefit to a consumer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating a distribution system according to a first embodiment of the present invention. 
         FIG. 2  is a block diagram illustrating hardware of a charge/discharge control device according to the first embodiment of the present invention. 
         FIG. 3  is a block diagram illustrating the charge/discharge control device according to the first and second embodiments of the present invention. 
         FIG. 4  is a graph illustrating first price information according to the first embodiment of the present invention. 
         FIG. 5  is a diagram illustrating the first price information according to the first embodiment of the present invention. 
         FIG. 6  is a diagram illustrating second price information according to the first embodiment of the present invention. 
         FIG. 7  is a diagram illustrating a control plan according to the first embodiment of the present invention. 
         FIG. 8  is a flowchart illustrating an operation of a planning unit according to the first embodiment of the present invention. 
         FIG. 9  is a conceptual diagram illustrating electric power input to/output from a storage battery according to the first embodiment of the present invention. 
         FIG. 10  is a diagram illustrating a state of a consumer, control of the storage battery, and the like according to the first embodiment of the present invention. 
         FIG. 11  is a flowchart illustrating an operation of the charge/discharge control device according to the first embodiment of the present invention. 
         FIG. 12  is a graph illustrating fourth price information according to a second embodiment of the present invention. 
         FIG. 13  is a flowchart illustrating an operation of the charge/discharge control device according to the second embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     At least the following matters will become apparent from descriptions of the present specification and of the accompanying drawings. 
     First Embodiment 
     ===Distribution System=== 
     The following describes a distribution system according to an embodiment with reference to  FIG. 1 .  FIG. 1  is a diagram illustrating a distribution system according to an embodiment of the present invention. 
     A distribution system  100  is an electric power system to supply a consumer  10  with electric power. The distribution system  100  includes a distribution transformer  101 , a distribution line L 1 , and the consumer  10 . 
     To a primary side of the distribution transformer  101 , electric power is supplied from an electric generator (not illustrated). To a secondary side of the distribution transformer  101 , one end of the distribution line L 1  is coupled. The distribution line L 1  extends downstream from the upstream one end thereof which is coupled to the secondary side of the distribution transformer  101 . 
     The consumer  10  is, for example, an ordinary household to which electric power is supplied from the distribution line L 1  and from which electric power is supplied to the distribution line L 1 . The consumer  10  includes a measuring device M 1 , a charge/discharge device  11 , a storage battery  12 , a load R 1 , a charge/discharge control device  3 , and a distributed power supply G 1 . Note that the consumer  10  may include a plurality of the loads R 1  and the distributed power supplies G 1 . 
     The load R 1  is an electric power load to which electric power W 1  based on the amount of power consumption of the load R 1  is supplied. 
     The measuring device M 1  is, for example, a smart meter that measures the supply power supplied from the distribution line L 1  to the consumer  10  and measures the electric power supplied from the consumer  10  to the distribution line L 1 . The measuring device M 1  measures the amount of power consumption of the load R 1  and the amount of power generation of the distributed power supply G 1 . The measuring device M 1  outputs measurement information indicative of these measurement results. Moreover, the measuring device M 1  receives first price information T 1  from, for example, an electric power company (not illustrated) and outputs this first price information T 1 . Note that the details of the first price information T 1  will be described later. 
     The distributed power supply G 1  is, for example, a photovoltaic power generation device that outputs electric power W 2  based on the amount of power generation and supplies the electric power to the load R 1  or the like. 
     The storage battery  12  is coupled to the distributed power supply G 1  and the load R 1 , and is charged and discharged. 
     The charge/discharge device  11  is a device that is controlled by the charge/discharge control device  3  so as to charge/discharge the storage battery  12  and stop charging and discharging thereof. 
     The charge/discharge control device  3  creates a plan T 3  for controlling charging and discharging of the storage battery  12  and controls the charge/discharge device  11 . 
     ===Charge/Discharge Control Device=== 
     The following describes a distribution system of an embodiment of the present invention with reference to  FIG. 2  and  FIG. 3 .  FIG. 2  is a block diagram illustrating hardware of the charge/discharge control device according to an embodiment of the present invention.  FIG. 3  is a block diagram illustrating the charge/discharge control device according to an embodiment of the present invention. 
     The charge/discharge control device  3  includes a Central Processing Unit (CPU)  31 , a communication device  32 , a storage device  33 , a display device  34 , and an input device  35 . The CPU  31  executes a program stored in the storage device  33 , to perform various functions of the charge/discharge control device  3 , and integrally controls the charge/discharge control device  3 . The storage device  33  stores the above-described program and various pieces of information. The display device  34  is a display that displays information of the charge/discharge control device  3 . The input device  35  is, for example, a keyboard and a computer mouse through which information is input to the charge/discharge control device  3 . The communication device  32  performs communication between the measuring device M 1  and the charge/discharge device  11  via a communication network  300 . The communication unit  32  receives the measurement information and first price information T 1  from the measuring device M 1 . 
     The charge/discharge control device  3  further includes a planning unit  36 , a surplus determining unit  37  (first determining device), an economic efficiency determining unit  38  (second determining device and third determining device), an accumulated unit price calculating unit  39 , a control unit  40  (also referred to as “various functions of the charge/discharge control device  3 ”). The various functions of the charge/discharge control device  3  are achieved by execution of a program stored in the storage device  33  by the CPU  31 . 
     The planning unit  36  creates the control plan T 3  for the storage battery  12  based on the first price information T 1 . 
     The surplus determining unit  37  performs determination with respect to PV surplus electricity generated in the consumer  10 . The PV surplus electricity indicates a surplus with respect to the electric power W 2  in the consumer  10 . The PV surplus electricity is generated when a value of the electric power W 2  exceeds a value of the electric power W 1 . The PV surplus electricity is, for example, supplied from the consumer  10  to the distribution line L 1  and sold from the consumer  10  to an electric power company. Alternatively, the PV surplus electricity is, for example, supplied to the storage battery  12 , to charge the storage battery  12 . 
     The economic efficiency determining unit  38  performs determination with respect to an economic advantage based on control of charge and discharge of the storage battery  12 . The accumulated unit price calculating unit  39  calculates an accumulated charging unit price X (accumulation price). The control unit  40  (second control device) controls the charge/discharge device  11 , so as to control charge and discharge of the storage battery  12 . Note that the economic efficiency determining unit  38  and the control unit  40  correspond to a first control device. 
     ===First Price Information=== 
     The following describes the first price information according to an embodiment of the present invention with reference to  FIG. 4  and  FIG. 5 .  FIG. 4  is a graph illustrating the first price information according to an embodiment of the present invention.  FIG. 5  is a diagram illustrating the first price information according to an embodiment of the present invention. 
     In the first price information T 1 , time slots, planned values of electric power prices, and planned values of PV purchase prices are associated with one another. 
     The electric power price is determined based on real-time pricing. The real-time pricing means, for example, an electric power rate system in which the electric power prices vary with a time slot having e.g., one hour, in a day. 
     The electric power price means a price (unit price) of the electric power supplied from the distribution line L 1  to the consumer  10  (also referred to as “purchase electric power”) and a price (unit price) of the electric power supplied from the consumer  10  to the distribution line L 1  (also referred to as a “selling electric power”) by discharging of the storage battery  12 . Note that the electric power supplied from the consumer  10  to the distribution line L 1  includes the selling electric power and the PV surplus electricity, which is different from the selling electric power. In the first price information T 1 , the price of the selling electric power and the price of the purchase electric power are the same. That is, the first price information T 1  indicates that both the price of the selling electric power in the time slot B 1  and the price of the purchase electric power in the time slot B 1  are A 1 , and similar information. 
     Further, the PV purchase price is determined based on a unit price variation. The PV purchase price indicates a unit selling price of the PV surplus electricity when the consumer  10  sells the PV surplus electricity. The PV purchase price, for example, varies with a time slot having e.g., one hour, in a day. The first price information T 1  indicates that the PV purchase price in the time slot B 1  is E 1 , and similar information. 
     Further, the first price information T 1  ( FIG. 4 ) indicates that the electric power prices are higher than the PV purchase prices in the time slots B 1  to B 11 , the electric power prices are lower than the PV purchase prices in the time slots B 12  to B 15 , and the electric power prices are higher than the PV purchase prices in the time slots B 16  to B 24 . 
     ===Planning Unit=== 
     The following describes the planning unit according to an embodiment of the present invention with reference to  FIG. 5  to  FIG. 8 .  FIG. 6  is a diagram illustrating second price information according to an embodiment of the present invention.  FIG. 7  is a diagram illustrating a control plan according to an embodiment of the present invention. Note that, in  FIG. 7 , any of control among charge, discharge, and stop is set in time slots other than the time slots B 2 , B 7 , B 9 , B 10 , B 12 , and B 15  among the time slots B 1  to B 24 . However, for convenience of explanation, the description thereof is omitted. In  FIG. 7 , charge means that the storage battery  12  is charged, discharge means that the storage battery  12  is discharged, and stop means that the storage battery  12  is neither charged nor discharged.  FIG. 8  is a flowchart illustrating an operation of the planning unit according to an embodiment of the present invention. 
     &lt;Outline&gt; 
     The planning unit  36  rearranges the first price information T 1  to create second price information T 2 . Thereafter, the planning unit  36  selects a pair of time slots in the second price information T 2 , and sets control in the selected pair of time slots. The planning unit  36  sets control, for example, in all the time slots of 24 hours in the first price information T 1 . The planning unit  36  creates the control plan T 3  in which the settings of such control have been reflected. 
     &lt;Details&gt; 
     The planning unit  36  obtains the first price information T 1  (Step S 11 ). The planning unit  36  sorts the combinations of the time slots and the electric power prices corresponding to these time slots, in the first price information T 1 , in the order of ascending electric power prices, to create the second price information T 2  (Step S 12 ). Note that  FIG. 6  illustrates a combination indicative of the lowest price A 10  among A 1  to A 24  on the uppermost section while a combination indicative of the highest price A 6  on the lowermost section. 
     The planning unit  36  sets  1  as a value of a variable K (Step S 13 ). Note that the variable K is used to select a pair of electric power prices from the second price information T 2 . When the value of the variable K is 1, the planning unit  36  selects the electric power prices A 10  and A 6 . When the value of the variable K is 2, the planning unit  36  selects the electric power prices A 11  and A 7 . 
     The planning unit  36  calculates a charge/discharge price ratio based on the selected pair of electric power prices A 10  and A 6 . Specifically, the planning unit  36  employs, as the charge/discharge price ratio when the value of the variable K is 1, a result of a division performed using A 10 , which is lower electric power price of the pair of electric power prices, as a dividend, and A 6 , which is a higher electric power price, as a divisor. 
     C k  and C 24-(k-1)  at Step S 14  correspond to the electric power price in the second price information T 2 . The “k” in C k  and C 24-(k-1)  corresponds to the variable K. For example, when the value of the variable K is 1, C k  at Step S 14  is C 1  and C 24(k-1)  is C 24 . At this time, the index of C indicates the ascending order of the electric power prices in the second price information T 2 . Accordingly, C 1  and C 24  indicate A 10  and A 6  in the second price information T 2 , respectively. That is, for example, when the value of the variable K is 1, C k  indicates A 10 , and C 24(k-1)  indicates A 6 . Further, for example, when the value of the variable K is 2, C k  indicates A 11 , and C 24(k-1)  indicates A 7 . 
     The planning unit  36  determines (judges) whether the charge/discharge price ratio is smaller than charge/discharge efficiency of an electricity storage system (also referred to as “charge/discharge efficiency”) (Step S 14 ). 
     The charge/discharge efficiency is a product of charge efficiency p when the storage battery  12  is charged with electric power and discharge efficiency q when the storage battery  12  that is charged with electric power is discharged. For example, the charge efficiency p of 0.9 means that, when the electric power of 1 (kWh) is supplied to the storage battery  12 , electric power corresponding to 0.9 (kWh), which is equivalent to 0.9 times of 1 (kWh), is charged. Further, for example, the discharge efficiency q of 0.9 means that, when the electric power corresponding to 1 (kWh) has been charged to the storage battery  12  and the electric power charged to the storage battery  12  is all discharged, the electric power of 0.9 (kWh), which is equivalent to 0.9 times of 1 (kWh), is output from the storage battery  12 . 
     For example, when it is determined (judged) at Step St 14  that the charge/discharge price ratio is smaller than the charge/discharge efficiency (YES at Step S 14 ), the planning unit  36  sets charge and discharge in the time slot corresponding to the selected pair of electric power prices, assuming that the economic advantage for the consumer  10  is brought. Specifically, the planning unit  36  sets charge control in the time slot B 10  corresponding to A 10  which is lower one of the pair of electric power prices, and sets discharge control in the time slot B 6  corresponding to A 6  which is higher electric power price (Step S 15 ). At this time, the planning unit  36  reflects the setting results in the control plan T 3 . 
     Meanwhile, for example, when it is determined (judged) at Step S 14  that the charge/discharge price ratio is not smaller than the charge/discharge efficiency (NO at Step S 14 ), the planning unit  36  sets stop in both the time slots corresponding to the selected pair of electric power prices, assuming that the economic advantage for the consumer  10  is not brought (Step S 17 ). At this time, the planning unit  36  reflects the setting results in the control plan T 3 . 
     The planning unit  36  determines whether the value of the variable K is 12 (Step S 16 ). For example, when the planning unit  36  determines that the value of the variable K is not 12 (NO at Step S 16 ), the planning unit  36  adds 1 to the value of the variable K (Step S 18 ) and then executes the determination at Step S 14  again, assuming that the control has not yet been set to all the time slots in the second price information T 2 . Meanwhile, for example, when the planning unit  36  determines that the value of the variable K is 12 (YES at Step S 16 ), the planning unit  36  ends the operation, assuming that the control has been set to all the time slots in the second price information T 2 . 
     ===Surplus Determining Unit=== 
     The following describes the surplus determining unit according to an embodiment of the present invention with reference to  FIG. 1 . 
     The surplus determining unit  37  determines whether the amount of power generation of the distributed power supply G 1  is larger than the amount of power consumption of the load R 1 , based on the measurement information received by the communication device  32 . 
     When the surplus determining unit  37  determines that the amount of power generation is larger than the amount of power consumption, this means that the PV surplus electricity is generated. Therefore, it is preferable to control the charge/discharge of the storage battery  12  using this PV surplus electricity, so as to bring the economic advantage (economic benefit) to the consumer  10 . For example, in this case, the charge/discharge control device  3  performs control so as to avoid double power generation in the consumer  10 , performs control so as to increase the electric energy of the PV surplus electricity which is to be sold by the consumer  10 , and performs control so as to reduce the accumulated charging unit price X. Note that, when the surplus determining unit  37  determines that the amount of power generation is smaller than the amount of power consumption, this means that the PV surplus electricity is not generated. 
     ===Accumulated Unit Price Calculating Unit=== 
     The following describes the accumulated unit price calculating unit according to an embodiment of the present invention with reference to  FIG. 9 .  FIG. 9  is a conceptual diagram illustrating electric power input to/output from the storage battery according to an embodiment of the present invention. 
     The accumulated unit price calculating unit  39  calculates dischargeable electric energy S and calculates the accumulated charging unit price X. 
     The dischargeable electric energy S corresponds to the maximum value of the electric energy that can be discharged based on remaining accumulated electric energy Wb of the storage battery  12 . The remaining accumulated electric energy Wb corresponds to the amount of charge that is charged at the present point of time in a charging capacity We of the storage battery  12 . The accumulated unit price calculating unit  39  calculates the dischargeable electric energy S based on charging electric energy Wt, which indicates the electric energy supplied to the storage battery  12 , and calculates the dischargeable electric energy S based on the remaining accumulated electric energy Wb. Specifically, the accumulated calculating unit  39  calculates the dischargeable electric energy S using Expression (1) and Expression (2). 
       [Formula 1] 
       Dischargeable electric energy  S =remaining accumulated electric energy  Wb ×discharge efficiency  q   (1)
 
       Dischargeable electric energy  S =sum of charging electric energy  Wt ×charge efficiency  p ×discharge efficiency  q    (2)
 
     The accumulated charging unit price X is a price determined according to the amount of the price of purchase electric power accumulated to charge the storage battery  12 . The accumulated unit price calculating unit  39  calculates the accumulated charging unit price X using Expression (3). 
       [Formula 2] 
       Accumulated charging unit price  Xb =(dischargeable electric energy  Sa ×accumulated charging unit price  Xa +electric power price  At ×charging electric energy  Wt ×charge efficiency  p ×discharge efficiency  q )/dischargeable electric energy  Sb    (3)
 
     Note that the accumulated charging unit prices Xa and Xb indicate the accumulated charging unit price X in a time A and the accumulated charging unit price X in a time B after the time A, respectively. The dischargeable electric energies Sa and Sb indicate the dischargeable electric energy S in the time A and the dischargeable electric energy S in the time B, respectively. The electric power price At indicates the electric power price in a time slot from the time A to the time B. The charging electric energy Wt indicates the charging electric energy in the time slot from the time A to the time B. 
     ===Economic Efficiency Determining Unit and Control Unit=== 
     The following describes the economic efficiency determining unit and the determining unit according to an embodiment of the present invention with reference to  FIG. 7  and  FIG. 10 .  FIG. 10  is a diagram illustrating a state of the consumer, control of the storage battery, and the like according to an embodiment of the present invention. 
     The economic efficiency determining unit  38  performs determination with respect to the economic advantage brought to the consumer  10 . 
     =Time Slot During which Storage Battery is Set to be Charged= 
     In the time slot during which the charge is set in the control plan T 3  (also referred to as “estimated (planned) charging time slot”), the economic efficiency determining unit  38  determines whether the electric power price is higher than or lower than the PV purchase price, and determines whether the PV purchase price is higher than or lower than the accumulated charging unit price X. Further, in the estimated charging time slot, the economic efficiency determining unit  38  determines whether the PV purchase price is higher than or lower than the sum of the accumulated charging unit price X and a predetermined unit price. 
     =Time Slot During which Storage Battery is Set to be Discharged= 
     In the time slot during which discharge is set in the control plan T 3  (also referred to as “estimated discharging time slot”), the economic efficiency determining unit  38  determines whether the PV purchase price is higher than or lower than the electric power price, and determines whether the PV purchase price is higher than or lower than the accumulated charging unit price X. Further, in the estimated discharging time slot, the economic efficiency determining unit  38  determines whether a price according to the PV purchase price is higher than or lower than the accumulated charging unit price X. Note that the economic efficiency determining unit  38  calculates the price according to the PV purchase price with Expression (4). 
       [Formula 3] 
       Price according to  PV  purchase price ( PV  purchase price  Bt /charge efficiency  p ×discharge efficiency  q )+predetermined price  (4)
 
     =Time Slot During which Storage Battery is Set to be Neither Charged Nor Discharged= 
     In the time slot during which stop is set in the control plan T 3  (also referred to as “estimated stop time slot”), the economic efficiency determining unit  38  determines whether the electric power price is higher than or lower than the accumulated charging unit price X, determines whether the price according to the electric power price is higher than or lower than the accumulated charging unit price X, or determines whether the electric power price is higher than or lower than the sum of the accumulated charging unit price X and the predetermined unit price. 
     The economic efficiency determining unit  38  calculates the price according to the electric power price with Expression (5). 
       [Formula 4] 
       Price according to electric power price=electric power price  At /(charge efficiency  p ×discharge efficiency  q )+predetermined price  (5)
 
     The control unit  40  controls charge and discharge of the storage battery  12 , based on the determination result of the economic efficiency determining unit  38 . Note that, in the respective predetermined unit prices in Expressions (4) and (5), the predetermined unit price in the sum of the accumulated charging unit price X and the predetermined unit price at Step S 25 , and the predetermined unit price in the sum of the accumulated charging unit price X and the predetermined unit price at Step S 34  are 0 or positive values. The values maybe different from one another, may be the same value, or may be set based on information input through the input device  35 . Further, these predetermined unit prices provide a function as margins for determination by the economic efficiency determining unit  38 . 
     ===Operation of Charge/Discharge Control Device=== 
     The following describes an operation of the charge/discharge control device according to an embodiment of the present invention, with reference to  FIG. 1 ,  FIG. 10 , and  FIG. 11 .  FIG. 11  is a flowchart illustrating the operation of the charge/discharge control device according to an embodiment of the present invention. 
     The charge/discharge control device  3  reads the final accumulated charging unit price X, dischargeable electric energy S, and control plan T 3  of the previous day (Step S 21 ). Note that the storage device  33  may store these pieces of information to be read. 
     The charge/discharge control device  3  determines whether the current time slot is any of the estimated charging time slot, the estimated discharging time slot, and the estimated stop time slot (Step S 22 ). For example, when the current time slot is the time slot B 2 , B 7 , or B 10  ( FIG. 7 ), the charge/discharge control device  3  determines that the time slot is the estimated stop time slot, the estimated discharging time slot, or the estimated charging time slot, respectively. 
     =Control of Estimated Charging Time Slot= 
     When the charge/discharge control device  3  determines that the time slot is the estimated charging time slot at Step S 22 , the surplus determining unit  37  determines whether the amount of power generation of the distributed power supply G 1  is larger than or smaller than the amount of power consumption of the load R 1  (Step S 31 ). When the surplus determining unit  37  determines that that the amount of power generation is smaller than the amount of power consumption (NO at Step S 31 ), the control unit  40  performs control so that the storage battery  12  is charged within a range of contracted electric power (Step S 35 ). Meanwhile, when the surplus determining unit  37  determines that the amount of power generation is larger than the amount of power consumption (YES at Step S 31 ), the following determination and control are performed, assuming that the PV surplus electricity is generated. 
     &lt;Electric Power Price and PV Purchase Price&gt; 
     The economic efficiency determining unit  38  determines whether the electric power price is higher than or lower than the PV purchase price (Step S 32 ). When the economic efficiency determining unit  38  determines that the electric power price is higher than the PV purchase price (YES at Step S 32 ), this means that the economic efficiency determining unit  38  determines the economic advantage being brought to the consumer  10  by charging the storage battery  12 . In this case, the control unit  40  performs the operation at Step S 35 . In this case, since the PV surplus electricity is supplied to the storage battery  12 , the electric energy of the purchase electric power is reduced. Therefore, the sum of money for a consideration paid from the consumer  10  to the electric power company is reduced, to bring the economic advantage to the consumer  10 . 
     Meanwhile, when the economic efficiency determining unit  38  determines that the electric power price is lower than the PV purchase price (NO at Step S 32 ), the economic efficiency determining unit  38  determines whether the PV purchase price is higher than or lower than the accumulated charging unit price X (Step S 33 ). 
     &lt;PV Purchase Price and Accumulated Charging Unit Price X&gt; 
     When the economic efficiency determining unit  38  determines that the PV purchase price is lower than the accumulated charging unit price X (YES at Step S 33 ), this means that the economic efficiency determining unit  38  determines the economic advantage being brought to the consumer  10  by charging the storage battery  12 . In this case, the control unit  40  performs the operation at Step S 35 . This brings the economic advantage similar to that in the case of YES at Step S 32 . Further, in this case, the sum of money for the accumulated charging unit price X is reduced, to bring the economic advantage to the consumer  10 . 
     Meanwhile, when the economic efficiency determining unit  38  determines that the PV purchase price is higher than the accumulated charging unit price X (NO at Step S 33 ), the economic efficiency determining unit  38  determines whether the PVpurchase price is higher than or lower than the sum of the accumulated charging unit price X and the predetermined unit price (Step S 34 ). 
     &lt;PV Purchase Price and Sum of Accumulated Charging Unit Price X and Predetermined Unit Price&gt; 
     When the economic efficiency determining unit  38  determines that the PV purchase price is higher than the sum of the accumulated charging unit price X and the predetermined unit price (YES at Step S 34 ), this means that the economic efficiency determining unit  38  determines the economic advantage being brought to the consumer  10  by neither charging nor discharging the storage battery  12 . In this case, the control unit  40  performs control so that the storage battery  12  is neither charged nor discharged (Step S 26 ). In this case, since the PV surplus electricity is not supplied to the storage battery  12 , the electric energy of the PV surplus electricity sold from the consumer  10  to the electric power company can be increased. Therefore, the sum of money for the consideration paid from the electric power company to the consumer  10  is increased, to bring the economic advantage to the consumer  10 . 
     Meanwhile, when the economic efficiency determining unit  38  determines that the PV purchase price is lower than the sum of the accumulated charging unit price X and the predetermined unit price (NO at Step S 34 ), this means that the economic efficiency determining unit  38  determines the economic advantage not being brought to the consumer  10  by neither charging nor discharging the storage battery  12 . In this case, the control unit  40  performs the operation at Step S 35 . 
     After the above, the charge/discharge control device  3  integrates the charging electric energy Wt (Step S 36 ), calculates the dischargeable amount S (Step S 37 ), and calculates the accumulated charging unit price X (Step S 38 ). Note that, at Step S 37 , the charge/discharge control device  3  assumes, as the dischargeable electric energy S, the sum of the dischargeable electric energy S before being charged at Step S 35 , and the product of the charging electric energy Wt, which has been integrated at Step S 36 , the charge efficiency p, and the discharge efficiency q. 
     The charge/discharge control device  3  determines whether control has been performed in all the time slots in the charge plan T 3  (Step S 58 ). That is, the charge/discharge control device  3  determines whether all the control of the storage battery  12  in a day has been performed. When the charge/discharge control device  3  determines that all the control of the storage battery  12  in a day has been performed (YES at Step S 58 ), the charge/discharge control device  3  ends the operation. Meanwhile, when the charge/discharge control device  3  does not determine that all the control of the storage battery  12  in a day has been performed (NO at Step S 58 ), the charge/discharge control device  3  performs determination at Step S 22  again. 
     =Control of Estimated Discharging Time Slot= 
     When the charge/discharge control device  3  determines that the time slot is the estimated discharging time slot at Step S 22 , the surplus determining unit  37  performs determination at Step S 41 . The determination at Step S 41  is similar to the determination at Step S 31 . When the surplus determining unit  37  determines that the amount of power generation is smaller than the amount of power consumption (NO at Step S 41 ), the control unit  40  performs control so that the storage battery  12  is discharged within a range of not causing an adverse current (Step S 55 ). Note that “within a range of not causing an adverse current” may indicate, for example, within a range of the electric energy set in advance by the consumer  10 . Thereafter, the charge/discharge control device  3  integrates discharging electric energy Pt (Step S 56 ), calculates the dischargeable electric energy S (Step S 57 ), and then performs the determination at Step S 58 . Note that, at Step S 57 , the charge/discharge control device  3  assumes, as the dischargeable electric energy S, a difference between the discharging electric energy Pt, which has been integrated at Step S 56 , and the dischargeable electric energy S before being discharged at Step S 55 . 
     At Step S 41 , when the surplus determining unit  37  determines that the amount of power generation is larger than the amount of power consumption (YES at Step S 41 ), the following determination and control are performed assuming that the PV surplus electricity is generated. 
     &lt;PV Purchase Price and Electric Power Price&gt; 
     The economic efficiency determining unit  38  determines whether the PV purchase price is higher than or lower than the electric power price (Step S 42 ). When the economic efficiency determining unit  38  determines that the PV purchase price is higher than the electric power price (NO at Step S 42 ), this means that the economic efficiency determining unit  38  determines the economic advantage being brought to the consumer  10  by stopping the charge and discharge of the storage battery  12 . In this case, the control unit  40  performs the operation at Step S 26 . In such a case, while the consumer  10  is prevented from entering a double power generation state, the consumer  10  is allowed to sell the PV surplus electricity to the electric power company. Therefore, the consideration is paid from the electric power company to the consumer  10 , to bring the economic advantage to the consumer  10 . 
     Note that the double power generation state means a state where both the PV surplus electricity and the electric power output by discharging the storage battery  12  are supplied to the distribution line L 1 . An electricity contract between the consumer  10  and the electric power company stipulates that the PV purchase price is to be reduced in the double power generation state. Therefore, the double power generation state needs to be prevented so as to bring and increase the economic advantage to the consumer  10 . 
     At Step S 42 , when the economic efficiency determining unit  38  determines that the PV purchase price is lower than the electric power price (YES at Step S 42 ), the economic efficiency determining unit  38  determines whether the PV purchase price is higher than or lower than the accumulated charging unit price X (Step S 43 ). 
     &lt;PV Purchase Price and Accumulated Charging Unit Price X&gt; 
     When the economic efficiency determining unit  38  determines that the PV purchase price is higher than the accumulated charging unit price X (NO at Step S 43 ), this means that the economic efficiency determining unit  38  determines the economic advantage being brought to the consumer  10  by stopping charge and discharge of the storage battery  12 . In this case, the control unit  40  performs the operation at Step S 26 . This brings the economic advantage similar to that in the case of NO at Step S 42 . 
     At Step S 43 , when the economic efficiency determining unit  38  determines that the PV purchase price is lower than the accumulated charging unit price X (YES at Step S 43 ), the economic efficiency determining unit  38  determines whether the price according to the PV purchase price is higher than or lower than the accumulated charging unit price X (Step S 44 ). 
     &lt;Price According to PV Purchase Price and Accumulated Charging Unit Price X&gt; 
     When the economic efficiency determining unit  38  determines that the price according to the PV purchase price is lower than the accumulated charging unit price X (YES at Step S 44 ), this means that the economic efficiency determining unit  38  determines the economic advantage being brought to the consumer  10  by charging the storage battery  12 . In this case, the control unit  40  performs control so that the PV surplus electricity is charged to the storage battery  12  (Step S 45 ). This brings the economic advantage similar to that in the case of YES at Step S 33 . Further, this prevents the consumer  10  from entering the double power generation state. After the above, the charge/discharge control device  3  performs the operations at Steps S 46  to S 48  and then performs the determination at Step S 58 . Note that the operations at Steps S 46  to S 48  are similar to the operations at Steps S 36  to S 38 , respectively. 
     Meanwhile, when the economic efficiency determining unit  38  determines that the price according to the PV purchase price is higher than the accumulated charging unit price X (NO at Step S 44 ), this means that the economic efficiency determining unit  38  determines the economic advantage not being brought to the consumer  10  by charging the storage battery  12 . In this case, the control unit  40  performs the operation at S 26 . 
     =Control of Estimated Stop Time Slot= 
     When the charge/discharge control device  3  determines that the time slot is the estimated stop time slot at Step S 22 , the economic efficiency determining unit  38  determines whether the electric power price is higher than or lower than the accumulated charging unit price X (Step S 23 ). After performing the determination at Steps S 24  and S 25  based on the determination results at Step S 23 , the charge/discharge control device  3  performs predetermined control. 
     Second Embodiment 
     A charge/discharge control device  3 B ( FIG. 3 ) according to the second embodiment has a configuration other than the economic efficiency determining unit  38  in the charge/discharge control device  3  of the first embodiment. In the charge/discharge control device  3 B, the planning unit  36  and the control unit  40  are changed to a planning unit  36 B and a control unit  40 B, respectively. The charge/discharge control device  3 B other than these components has a configuration similar to that of the charge/discharge control device  3 . 
     ===Charge/Discharge Control Device=== 
     The following describes the charge/discharge control device according to an embodiment of the present invention with reference to  FIG. 3 ,  FIG. 12 , and  FIG. 13 .  FIG. 12  is a graph illustrating fourth price information according to an embodiment of the present invention.  FIG. 13  is a flowchart illustrating an operation of the charge/discharge control device according to an embodiment of the present invention. Operations similar to the operations in  FIG. 11  will be given the similar reference numerals, and the descriptions thereof are omitted. 
     The fourth price information T 4  is information similar to the first price information T 1  ( FIG. 4 ). Note that the PV purchase price in the fourth price information T 4  is determined based on a fixed unit price. The fixed unit price means that the unit price does not vary with a time slot. The PV purchase price in the fourth price information T 4  is set higher than the electric power price. 
     The charge/discharge control device  3 B includes the planning unit  36 B and the control unit  40 B. 
     The planning unit  36 B creates a predetermined control plan based on the fourth price information T 4 . Note that the configuration that the planning unit  36 B creates the predetermined control plan is similar to the configuration that the planning unit  36  creates the control plan T 3 . 
     The control unit  40 B controls charge and discharge of the storage battery  12  based on the determination result of the surplus determining unit  37 . 
     Specifically, the surplus determining unit  37  performs the determination at Steps S 61  and S 62  ( FIG. 13 ) similar to Steps S 31  and S 41  ( FIG. 11 ). When the surplus determining unit  37  determines that the amount of power generation is smaller than the amount of power consumption (NO at Step S 61  and NO at Step S 62 ), the control unit  40 B performs the operations at Steps S 35  and S 55 . Meanwhile, when the surplus determining unit  37  determines that the amount of power generation is larger than the amount of power consumption (YES at Step S 61  and YES at Step S 62 ), the control unit  40 B performs control so that the storage battery  12  is neither charged nor discharged, assuming that the PV surplus electricity is generated (Step S 26 ). Note that, in the case of YES at Step S 61 , this brings the economic advantage similar to that in the case of YES at Step S 34 . Further, in the case of YES at Step S 62 , this brings the economic advantage similar to that in the case of NO at Step S 42 . 
     As described above, the charge/discharge control device  3  controls charge and discharge of the storage battery  12  in the consumer  10 . The charge/discharge control device  3  includes the load R 1 , the distributed power supply G 1 , which supplies the load R 1  with electric power, and the storage battery  12 , which is coupled to the load R 1  and the distributed power supply G 1 . The charge/discharge control device  3  includes the surplus determining unit  37  and the control unit  40 . The surplus determining unit  37  determines whether the amount of power generation of the distributed power supply G 1  is larger than the amount of power consumption of the load R 1 . When the surplus determining unit  37  determines that the amount of power generation of the distributed power supply G 1  is larger than the amount of power consumption of the load R 1 , the control unit  40  controls charge and discharge of the storage battery  12  so that the economic advantage (economic benefit) is brought to the consumer  10  by control of the storage battery  12 . Therefore, charge and discharge of the storage battery  12  can be controlled so as to bring the economic advantage to the consumer  10 . 
     Further, the charge/discharge control device  3  includes the economic efficiency determining unit  38 . The control of the storage battery  12  is planned in advance with the control plan T 3 . When discharging the storage battery  12  is planned in the control plan T 3 , the economic efficiency determining unit  38  determines whether the PV purchase price (power selling price) of the PV surplus electricity is higher than or lower than the electric power price (power purchase price) of the purchase electric power (supply power) supplied to the consumer  10 . When the economic efficiency determining unit  38  determines that the PV purchase price is higher than the electric power price, the control unit  40  performs control so that the storage battery  12  is neither charged nor discharged regardless of the control plan T 3 . Thus, while the consumer  10  is prevented from entering the double power generation state, the consumer  10  is also allowed to sell the PV surplus electricity to the electric power company. Therefore, the consideration is paid from the electric power company to the consumer  10 , to bring the economic advantage to the consumer  10 . 
     Further, when the economic efficiency determining unit  38  determines that that PV purchase price is lower than the electric power price, the economic efficiency determining unit  38  determines whether the PV purchase price is higher than or lower than the accumulated charging unit price X. When the economic efficiency determining unit  38  determines that the PV purchase price is higher than the accumulated charging unit price X, the control unit  40  performs control so that the storage battery  12  is neither charged nor discharged regardless of the control plan T 3 . Thus, while the consumer  10  is prevented from entering the double power generation state, the consumer  10  is also allowed to sell the PV surplus electricity to the electric power company, to bring the economic advantage to the consumer  10 . 
     Further, when charging the storage battery  12  is planned with the control plan T 3 , the economic efficiency determining unit  38  determines whether the electric power price of the purchase electric power supplied to the consumer  10  is higher than or lower than the PV purchase price of the PV surplus electricity. When the economic efficiency determining unit  38  determines that the electric power price is higher than the PV purchase price, the control unit  40  performs control so that the storage battery  12  is charged based on the control plan T 3 . Thus, since the PV surplus electricity is supplied to the storage battery  12 , the electric energy of the purchase electric power reduces. Therefore, the sum of money for the consideration paid from the consumer  10  to the electric power company is reduced, to bring the economic advantage to the consumer  10 . 
     Further, when the economic efficiency determining unit  38  determines that the electric power price is lower than the PV purchase price, the economic efficiency determining unit  38  determines whether the PV purchase price is higher than or lower than the accumulated charging unit price X. When the economic efficiency determining unit  38  determines that the PV purchase price is lower than the accumulated charging unit price X, the control unit  40  performs control so that the storage battery  12  is charged based on the control plan T 3 . Therefore, the sum of money for the accumulated charging unit price X is reduced, to bring the economic advantage to the consumer  10 . 
     Further, when discharging the storage battery  12  is planned in the control plan T 3 , the economic efficiency determining unit  38  determines whether the economic advantage is brought to the consumer  10  by charging the storage battery  12 . When the economic efficiency determining unit  38  determines that the economic advantage is brought to the consumer  10 , the control unit  40  performs control so that the storage battery  12  is charged regardless of the control plan T 3 . In this case, while the consumer  10  is prevented from entering the double power generation state, the sum of money for the accumulated charging unit price X is reduced, to bring the economic advantage to the consumer  10 . Meanwhile, when the economic efficiency determining unit  38  determines that the economic advantage is not brought to the consumer  10 , the control unit  40  performs control so that the storage battery  12  is neither charged nor discharged regardless of the control plan T 3 . In this case, the consumer  10  is prevented from entering the double power generation state. 
     Further, when the economic efficiency determining unit  38  determines that the price according to the PV purchase price is lower than the accumulated charging unit price X, this means that the economic efficiency determining unit  38  determines the economic advantage being brought to the consumer  10  by charging the storage battery  12 . When the economic efficiency determining unit  38  determines that the price according to the PV purchase price is higher than the accumulated charging unit price X, this means that the economic efficiency determining unit  38  determines the economic advantage not being brought to the consumer  10  by charging the storage battery  12 . Accordingly, the accuracy of determining whether the economic advantage is brought can be improved. 
     Further, when charging the storage battery  12  is planned with the control plan T 3 , the economic efficiency determining unit  38  determines whether the economic advantage is brought to the consumer  10  by neither charging nor discharging the storage battery  12 . When the economic efficiency determining unit  38  determines that the economic advantage is brought to the consumer  10 , the control unit  40  performs control so that the storage battery  12  is neither charged nor discharged regardless of the control plan T 3 . Thus, since the PV surplus electricity is not supplied to the storage battery  12 , the electric energy of the PV surplus electricity sold from the consumer  10  to the electric power company is increased. Therefore, the sum of money for the consideration paid from the electric power company to the consumer  10  is increased, to bring the economic advantage to the consumer  10 . When the economic efficiency determining unit  38  determines that the economic advantage is not brought to the consumer  10 , the control unit  40  performs control so that the storage battery  12  is charged based on the control plan T 3 . In this case, since the PV surplus electricity is supplied to the storage battery  12 , the electric energy of the purchase electric power can be reduced. 
     Further, when the economic efficiency determining unit  38  determines that the PV purchase price is higher than the sum of the accumulated charging unit price X and the predetermined unit price, this means that the economic efficiency determining unit  38  determines the economic advantage being brought to the consumer  10  by neither charging nor discharging the storage battery  12 . When the economic efficiency determining unit  38  determines that the PV purchase price is lower than the sum of the accumulated charging unit price X and the predetermined unit price, this means that the economic efficiency determining unit  38  determines the economic advantage not being brought to the consumer  10  by neither charging nor discharging the storage battery  12 . Accordingly, the accuracy of determining whether the economic advantage is brought can be improved. 
     Note that the first and the second embodiments are intended for easy understanding of the present invention and are not in any way to be construed as limiting the present invention. The present invention may be modified and improved without departing from the scope of the invention, and equivalents thereof are also encompassed by the invention. 
     The first embodiment describes that, in the case of YES at Step S 31 , the determination at Steps S 32  to S 34  and the control based on the determination results are performed; however, this should not be constructed in a limiting sense. For example, as determination after YES at Step S 31 , determination and control of at least one of Steps S 32  to S 34  may be performed. That is, for example, among Steps S 32  to S 34 , only any one of the steps may be provided. Alternatively, only Steps S 32  and S 33 , only Steps S 33  and S 34 , or only Steps S 32  and S 34  may be provided. Similarly, for example, in the case of YES at Step S 41 , determination and control of at least any one of Steps S 42  to S 44  may be performed. 
     Further, the first embodiment describes the case of the distributed power supply G 1  being the photovoltaic power generation device; however, this should not be constructed in a limiting sense. For example, the distributed power supply G 1  may be a wind power generator. 
     Further, the first embodiment describes that the planning unit  36  creates the control plan T 3 ; however, this should not be constructed in a limiting sense. For example, the control plan T 3  may be set in advance or information indicative of the control plan T 3  may be input via the input device  35 . 
     Further, the first embodiment describes that the first price information T 1  indicates the electric power prices for every one hour, and the like; however, this should not be constructed in a limiting sense. For example, the first price information T 1  may indicate the electric power prices for every 30 minutes or the like. 
     Further, the first embodiment describes that, in the first price information T 1 , the prices of the selling electric power are the same as the prices of the purchase electric powers, respectively; however, this should not be constructed in a limiting sense. For example, the price of the selling electric power and the price of the purchase electric power in the same time slot may be different from each other. 
     Further, using another charge/discharge control device having a configuration similar to the configuration of the charge/discharge control device  3 , for example, transmission and reception of electric power between the distribution line L 1  and an electric power storage device, such as a flywheel coupled to the distribution line L 1 , may be controlled. 
     Further, for example, the charge/discharge device  11  may perform the function of the charge/discharge control device  3 , and the measuring device M 1  may perform the function of the charge/discharge control device  3 . 
     REFERENCE SIGNS LIST 
     
         
           3 ,  3 B charge/discharge control device 
           10  consumer 
           12  storage battery 
           37  surplus determining unit 
           38  economic efficiency determining unit 
           40 ,  40 B control unit 
         G 1  distributed power supply 
         R 1  load