Patent Publication Number: US-10310587-B2

Title: Power-supply control apparatus, power-supply control method, server, power-supply control system, and storage medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2014-241371 filed on Nov. 28, 2014, the entire contents of which are incorporated herein by reference. 
     FIELD 
     An aspect of this disclosure relates to a power-supply control apparatus, a power-supply control method, a server, a power-supply control system, and a storage medium. 
     BACKGROUND 
     There exist technologies for reducing peak power indicating maximum power consumption to achieve stable power supply by using storage batteries provided for respective communities such as buildings, homes, and municipalities. 
     For example, there exists a technology where a server generates optimum charge-and-discharge plans for respective storage batteries and delivers the charge-and-discharge plans to control apparatuses for controlling charging and discharging of the storage batteries (see, for example, Japanese Laid-Open Patent Publication No. 2014-195363 and Japanese Laid-Open Patent Publication No. 2014-171330). As another example, there exists a technology where a charge-and-discharge plan covering multiple time periods is delivered for each storage battery and stored in a memory of a receiving end so that the charge-and-discharge plan stored in the memory can be used when the latest charge-and-discharge plan is not delivered (see, for example, Nagahara, Quevedo, Ostergaard, “Packetized Predictive Control and Sparse Representation for Networked Control”, Proceedings of 41st Symposium on Control Theory, pp. 131-134, 2012). 
     SUMMARY 
     According to an aspect of this disclosure, there is provided a power-supply control apparatus including a processor that executes a process. The process includes calculating, for a first time period, a first predictive value of total power consumption by the power-supply control apparatus and one or more other power-supply control apparatuses to which power is supplied from a power supply; and determining whether to allow a storage battery to be charged in the first time period based on the first predictive value for the first time period and previous information that is related to the first predictive value and obtained in a second time period before the first time period. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a drawing illustrating an exemplary power-supply control system; 
         FIGS. 2A through 2D  are drawings illustrating an exemplary storage battery system; 
         FIG. 3  is a block diagram illustrating an exemplary hardware configuration of a delivery server; 
         FIG. 4  is a block diagram illustrating an exemplary hardware configuration of a power-supply control apparatus; 
         FIG. 5  is a drawing illustrating exemplary functional configurations of a delivery server and a power-supply control apparatus of a power-supply control system; 
         FIG. 6  is a drawing illustrating time periods; 
         FIG. 7  is a table illustrating exemplary charge-and-discharge plans and additional information; 
         FIG. 8  is a table illustrating an exemplary charge-and-discharge plan; 
         FIGS. 9A and 9B  are graphs used to describe a total increase and a total decrease in power consumption; 
         FIG. 10  is a flowchart illustrating an exemplary process performed by a delivery server; 
         FIG. 11  is a flowchart illustrating an exemplary process performed by a power-supply control apparatus; 
         FIG. 12  is another flowchart illustrating an exemplary process performed by a power-supply control apparatus; 
         FIGS. 13A through 13C  are graphs used to describe effects of a power-supply control system; 
         FIGS. 14A through 14C  are graphs used to describe effects of a power-supply control system; and 
         FIG. 15  is a drawing illustrating a change made to a charge-and-discharge plan. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the related-art technology described above, the charge-and-discharge plan stored in the memory is not the latest charge-and-discharge plan. Therefore, if the current power usage status is different from the power usage status at the time when the charge-and-discharge plan was generated, executing the charge-and-discharge plan stored in the memory may increase peak power or cause a new peak. 
     An aspect of this disclosure makes it possible to provide a power-supply control apparatus, a power-supply control method, a server, a power-supply control system, and a storage medium that can reliably control a power supply. 
     Embodiments of the present invention are described below with reference to the accompanying drawings.  FIG. 1  is a drawing illustrating an exemplary power-supply control system  100  according to an embodiment. 
     The power-supply control system  100  may include a delivery server  200  and multiple storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N. The delivery server  200  and the storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N are connected to each other via, for example, a network. 
     The delivery server  200  may include a remaining amount database  210  and a power consumption database  220 . Also, a charge-and-discharge plan generation program  230  is installed in the delivery server  200 . The delivery server  200  generates charge-and-discharge plans for storage batteries of the storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N based on predictive values of power consumption (or energy consumption) and power usage status obtained by referring to the remaining amount database  210  and the power consumption database  220 , and delivers the charge-and-discharge plans to the storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N. In the present embodiment, “power consumption” indicates the total amount of power (or energy) supplied to the entire community including the storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N. 
     Also, the delivery server  200  attaches additional information to each of the charge-and-discharge plans to be delivered to the storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N. The additional information indicates a variation in the power consumption that is expected when the charge-and-discharge plans are executed. Details of the charge-and-discharge plan and the additional information are described later. 
     According to the present embodiment, the storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N are installed, for example, in an office X and each of which is connected to a load such as a personal computer that consumes power. Thus, in the present embodiment, the power consumption may indicate a total amount of power (or energy) supplied from a commercial power supply to the office X. 
     Each of the storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N includes a storage battery for supplying power to the load and a power-supply control apparatus for controlling charging and discharging of the storage battery. In the descriptions below, the storage battery systems  300 - 1 ,  300 - 2 , . . . , and  300 -N may be simply referred to as a “storage battery system  300 ” or “storage battery systems  300 ” when it is not necessary to distinguish them. 
     The storage battery system  300  of the present embodiment sends, to the delivery server  200 , remaining-amount data indicating the remaining amount of charge of the storage battery. The remaining-amount data is stored in the remaining amount database  210  of the delivery server  200 . 
     The power-supply control apparatus of the present embodiment includes a power-supply control program installed therein, and controls charging and discharging of the storage battery according to a delivered charge-and-discharge plan. Also, when the latest charge-and-discharge plan and additional information are not delivered, the power-supply control apparatus obtains a predictive value of power consumption that is predicted when charging and discharging are performed by the storage battery systems  300  based on previously-delivered charge-and-discharge plans and additional information, and controls the state of the storage battery based on the obtained predictive value. 
     Thus, the present embodiment makes it possible to reliably control a power supply for supplying power to a load even when the latest charge-and-discharge plan is not delivered from the delivery server  200 . 
     The storage battery system  300  is described below with reference to  FIGS. 2A through 2D . 
       FIGS. 2A through 2D  are drawings illustrating the storage battery system  300 .  FIG. 2A  illustrates the storage battery system  300 , and  FIGS. 2B through 2D  are used to describe operations of the storage battery system  300 . 
     As illustrated by  FIG. 2A , the storage battery system  300  includes a power-supply control apparatus  400  and a storage battery  500 , and is connected to a load  600 . The load  600  may be a single apparatus or a collection of apparatuses. 
     The power-supply control apparatus  400  controls charging and discharging of the storage battery  500  based on a charge-and-discharge plan delivered from the delivery server  200 . The storage battery  500  supplies power to the load  600 . When, for example, the storage battery system  300  is a notebook personal computer, the storage battery  500  is a battery of the notebook personal computer. 
     The power-supply control apparatus  400  performs control operations as illustrated by  FIGS. 2B through 2D . 
       FIG. 2B  illustrates an operation where the storage battery  500  is charged. The power-supply control apparatus  400  connects the storage battery  500  to a commercial power supply, and charges the storage battery  500  with power supplied from the commercial power supply. During this operation, power is supplied from the commercial power supply to the load  600 . Accordingly, the power consumption of the storage battery system  300  in the operation of  FIG. 2B  is a sum of power supplied from the commercial power supply to the storage battery  500  and power supplied from the commercial power supply to the load  600 . In the present embodiment, the operation of  FIG. 2B  is referred to as a “charging operation” of the storage battery  500 . 
       FIG. 2C  illustrates an operation where the storage battery  500  discharges electricity. The power-supply control apparatus  400  disconnects the storage battery  500  from the commercial power supply, and connects the storage battery  500  to the load  600 . As a result, power is supplied from the storage battery  500  to the load  600 . Accordingly, during the operation of  FIG. 2C , power is not supplied from the commercial power supply to the load  600  of the storage battery system  300 . In the present embodiment, the operation of  FIG. 2C  is referred to as a “discharging operation” of the storage battery  500 . 
       FIG. 2D  illustrates an operation where the storage battery  500  is neither charged nor discharged. The power-supply control apparatus  400  connects the load  600  to the commercial power supply, and disconnects the storage battery  500  from the commercial power supply and the load  600 . In this case, power is supplied from the commercial power supply to the load  600 . Accordingly, the power consumption of the storage battery system  300  in the operation of  FIG. 2D  equals the amount of power supplied to the load  600 . In the present embodiment, the operation of  FIG. 2D  is referred to as a “bypass operation”. 
     Next, an exemplary hardware configuration of the power-supply control system  100  of the present embodiment is described.  FIG. 3  is a block diagram illustrating an exemplary hardware configuration of the delivery server  200 . 
     The delivery server  200  is a computer including an input device  21 , an output device  22 , a drive  23 , a secondary storage  24 , a memory  25 , a processor  26 , and an interface  27  that are connected to each other via a bus B. 
     The input device  21  includes, for example, a keyboard and a mouse, and is used to input instructions (or operation signals). The output device  22  includes, for example, a display, and is used to display various windows and data. The interface  27  includes, for example, a modem and a LAN card, and is used to connect the delivery server  200  to a network. 
     The charge-and-discharge plan generation program  230  is at least a part of various programs for controlling the delivery server  200 . For example, the charge-and-discharge plan generation program  230  may be provided via a storage medium  28  or downloaded from a network. Examples of the storage medium  28  for storing the charge-and-discharge plan generation program  230  include storage media such as a compact disk read-only memory (CD-ROM), a flexible disk, and a magneto-optical disk that record information optically, electrically, or magnetically; and semiconductor memories such as a read-only memory (ROM) and a flash memory that record information electrically. 
     When the storage medium  28  storing the charge-and-discharge plan generation program  230  is mounted on the drive  23 , the charge-and-discharge plan generation program  230  is read by the drive  23  from the storage medium  28  and installed in the secondary storage  24 . On the other hand, when the charge-and-discharge plan generation program  230  is downloaded from a network, the charge-and-discharge plan generation program  230  is installed via the interface  27  in the secondary storage  24 . 
     The secondary storage  24  stores the installed charge-and-discharge plan generation program  230  and other necessary files and data. The memory  25  stores the charge-and-discharge plan generation program  230  read from the secondary storage  24  when the computer is started. The processor  26  executes the charge-and-discharge plan generation program  230  stored in the memory  25  to perform various processes described later. 
       FIG. 4  is a block diagram illustrating an exemplary hardware configuration of the power-supply control apparatus  400 . The power-supply control apparatus  400  includes a central processing unit (CPU)  41 , a random access memory (RAM)  42 , and a read-only memory (ROM)  43 . The ROM  43  stores a power-supply control program. The RAM  42  stores various values necessary for calculations performed by the CPU  41 . The CPU  41  executes the power-supply control program to implement functions of the power-supply control apparatus  400  described later. 
     Next, functional configurations of the delivery server  200  and the power-supply control apparatus  400  of the power-supply control system  100  are described with reference to  FIG. 5 .  FIG. 5  is a drawing illustrating exemplary functional configurations of the delivery server  200  and the power-supply control apparatus  400  of the power-supply control system  100 . 
     The delivery server  200  may include the remaining amount database  210  and the power consumption database  220 . Also, the delivery server  200  may include a power consumption predictor  231 , a charge-and-discharge plan generator  232 , an additional information calculator  233 , a remaining amount manager  234 , a power consumption manager  235 , and a deliverer  236  that are implemented by executing the charge-and-discharge plan generation program  230 . 
     The remaining amount database  210  stores the remaining amounts of charge of the storage batteries  500  of the storage battery systems  300 . The power consumption database  220  stores values (past power consumption values) indicating past power consumption in the office X. 
     The power consumption predictor  231  calculates predictive values of power consumption (predictive power consumption values) in the office X based on the past power consumption values stored in the power consumption database  220  and climate information input to the delivery server  200  from an external source. The predictive values of power consumption may be calculated according to a known power-consumption prediction technology. The climate information of the present embodiment includes, for example, information indicating a temperature such as an outside air temperature or an ambient temperature. 
     The charge-and-discharge plan generator  232  generates charge-and-discharge plans for multiple time periods each having a predetermined length of time based on the latest predictive values of power consumption calculated by the power consumption predictor  231  and the latest remaining-amount data of the storage batteries  500  stored in the remaining amount database  210 . More specifically, the charge-and-discharge plan generator  232  generates optimum charge-and-discharge plans by solving optimization problems for minimizing objective functions including peak power of power consumption. The charge-and-discharge plan generator  232  generates charge-and-discharge plans for the storage batteries  500  of all the storage battery systems  300  in the office X. “Time periods” of the present embodiment are described later in more detail. 
     The additional information calculator  233  calculates additional information to be attached to the charge-and-discharge plans for the storage batteries  500  of all the storage battery systems  300 . The additional information includes a total increase in the power consumption and a total decrease in the power consumption that are expected when the power-supply control apparatuses  400  of all the storage battery systems  300  control the storage batteries  500  according to the charge-and-discharge plans in a time period. 
     The remaining amount manager  234  stores, in the remaining amount database  210 , remaining-amount data of the storage batteries  500  sent from all the storage battery systems  300  in the office X. 
     The power consumption manager  235  obtains the amount of power supplied to the office X, i.e., power consumption values indicating power consumption in the office X, from, for example, an external power supply facility or a power meter provided in the office X, and stores the obtained power consumption values in the power consumption database  220 . 
     The deliverer  236  delivers the charge-and-discharge plans for the storage batteries  500  and the additional information calculated by the additional information calculator  233  to the corresponding power-supply control apparatuses  400  of all the storage battery systems  300  in the office X. Each time charge-and-discharge plans are generated, the deliverer  236  delivers the generated charge-and-discharge plans and additional information to all the storage battery systems  300 . 
     In the power-supply control apparatus  400  of the present embodiment, the CPU  41  executes the power-supply control program  410  to implement functions described below. 
     The power-supply control apparatus  400  may include an input receiver  411 , a communicator  412 , a storage battery monitor  413 , a power supply controller  414 , a plan presence determiner  415 , a power consumption predictor  416 , a first peak determiner  417 , a prediction corrector  418 , a second peak determiner  419 , and an increase determiner  420 . 
     The input receiver  411  receives various inputs to the power-supply control apparatus  400 . For example, the input receiver  411  receives a charge-and-discharge plan and additional information for the storage battery  500  connected to the power-supply control apparatus  400 . Also, the input receiver  411  receives power consumption values indicating power consumption in the office X from, for example, an external power supply facility or a power meter provided in the office X. These power consumption values are the same as the power consumption values that the delivery server  200  obtains. Further, the input receiver  411  receives climate information input from an external source. 
     The communicator  412  performs communications between the power-supply control apparatus  400  and external apparatuses. 
     The storage battery monitor  413  monitors the remaining amount of charge of the storage battery  500 . The monitored remaining amount of charge of the storage battery  500  is sent via the communicator  412  to the delivery server  200  as remaining-amount data. 
     The power supply controller  414  switches power supplies for supplying power to the load  600  and controls charging and discharging of the storage battery  500  according to a charge-and-discharge plan. Specifically, the power supply controller  414  performs one of the charging operation of the storage battery  500 , the discharging operation of the storage battery  500 , and the bypass operation described above. 
     The plan presence determiner  415  determines whether a charge-and-discharge plan and additional information received from the delivery server  200  are stored in, for example, a memory such as the RAM  42 . 
     The power consumption predictor  416  calculates predictive values of power consumption (predictive power consumption values) in the office X based on the power consumption values of the office X received by the input receiver  411  and the climate information input to the power-supply control apparatus  400  from an external source. The power consumption predictor  416  may be configured to calculate the predictive values of power consumption in a manner similar to that employed by the power consumption predictor  231  of the delivery server  200 . 
     The first peak determiner  417  determines whether a peak of power consumption exists in the nearest time period based on the predictive values of power consumption calculated by the power consumption predictor  416 . 
     When the first peak determiner  417  determines that the peak of power consumption does not exist in the nearest time period, the prediction corrector  418  corrects the predictive values of power consumption using the additional information stored in the RAM  42 . 
     The second peak determiner  419  determines whether a peak of power consumption exists in the nearest time period based on the corrected predictive values of power consumption (corrected predictive power consumption values) corrected by the prediction corrector  418 . 
     The increase determiner  420  determines whether a total increase included in additional information is greater than 0. 
     Details of the first peak determiner  417 , the prediction corrector  418 , the second peak determiner  419 , and the increase determiner  420  are described later. 
     Next, “time periods” of the present embodiment are described with reference to  FIG. 6 .  FIG. 6  is a drawing illustrating time periods. 
     In the present embodiment, a time period indicates duration T between a time point and another time point. For example, a time period between a time k and a time k+1 is referred to as a time period k′, a time period between the time k+1 and a time k+2 is referred to as a time period k′+1, and a time period between the time k+2 and a time k+3 is referred to as a time period k′+2. Accordingly, in the present embodiment, when charge-and-discharge plans are generated for H time periods from the time k, the H time periods correspond to time periods k′ through k′+H−1. 
     In the present embodiment, it is assumed that generation of charge-and-discharge plans and calculation of additional information are performed at the start time of each time period. That is, charge-and-discharge plans and additional information for the time period k′ are generated and calculated at the time k that is the start time of the time period k′, and are delivered to the power-supply control apparatuses  400  of the storage battery systems  300 . Similarly, charge-and-discharge plans and additional information for the time period k′+1 are generated and calculated at the time k+1 that is the start time of the time period k′+1 (or the end time of the time period k′), and are delivered to the power-supply control apparatuses  400  of the storage battery systems  300 . 
     Next, charge-and-discharge plans and additional information of the present embodiment are described with reference to  FIGS. 7 through 9B .  FIG. 7  is a table illustrating exemplary charge-and-discharge plans and additional information. 
       FIG. 7  illustrates exemplary charge-and-discharge plans and additional information for three time periods generated by the charge-and-discharge plan generator  232  of the delivery server  200  for the storage battery system  300 - 1 . 
     In this example, the delivery server  200  delivers, at the time k, charge-and-discharge plans and additional information of the storage battery system  300 - 1  for the time period k′, the time period k′+1, and the time period k′+2 to the power-supply control apparatus  400  of the storage battery system  300 - 1 . 
     In  FIG. 7 , the charge-and-discharge plan of the storage battery system  300 - 1  generated at the time k for the time period k′ is represented by S 1 [k′|k]. Also, the total increase and the total decrease in the additional information calculated at the time k for the time period k′ are represented by σc[k′|k] and σd[k′|k], respectively. 
     The total increase σc[k′|k] indicates an increase in power consumption in the time period k′ that is expected when all the storage battery systems  300  connected to the delivery server  200  operate according to charge-and-discharge plans in the time period k′. The total decrease σd[k′|k] indicates a decrease in power consumption in the time period k′ that is expected when all the storage battery systems  300  connected to the delivery server  200  operate according to charge-and-discharge plans in the time period k′. 
     Similarly, in  FIG. 7 , the charge-and-discharge plan, the total increase, and the total decrease generated and calculated at the time k for the time period k′+1 are represented by S 1 [k′+1|k], σc[k′+1|k], and σd[k′+1|k], respectively. Also in  FIG. 7 , the charge-and-discharge plan, the total increase, and the total decrease generated and calculated at the time k for the time period k′+2 are represented by S 1 [k′+2|k], σc[k′+2|k], and σd[k′+2|k], respectively. 
     The power-supply control apparatus  400  of the storage battery system  300 - 1  obtains the charge-and-discharge plans and the additional information for the three time periods at the time k that is the start time of the time period k′, and stores the charge-and-discharge plans and the additional information in, for example, the RAM  42 . 
     Next, at the time k+1 that is the start time of the time period k′+1 next to the time period k′, the delivery server  200  delivers charge-and-discharge plans and additional information of the storage battery system  300 - 1  for the time period k′+1, the time period k′+2, and the time period k′+3 to the power-supply control apparatus  400  of the storage battery system  300 - 1 . 
     The charge-and-discharge plan for the time period k′+1 generated at the time k+1 is not the same as the charge-and-discharge plan S 1 [k′+1|k] for the time period k′+1 generated at the time k. Also, the additional information for the time period k′+1 calculated at the time k+1 is not the same as the additional information for the time period k′+1 calculated at the time k. 
     Accordingly, in  FIG. 7 , the charge-and-discharge plan, the total increase, and the total decrease generated and calculated at the time k+1 for the time period k′+1 are represented by S 1 [k′+1|k+1], σc[k′+1|k+1], and σd[k′+1|k+1], respectively. Also in  FIG. 7 , the charge-and-discharge plan, the total increase, and the total decrease generated and calculated at the time k+1 for the time period k′+2 are represented by S 1 [k′+2|k+1], σc[k′+2|k+1], and σd[k′+2|k+1], respectively. Further in  FIG. 7 , the charge-and-discharge plan, the total increase, and the total decrease generated and calculated at the time k+1 for the time period k′+3 are represented by S 1 [k′+3|k+1], σc[k′+3|k+1], and σd[k′+3|k+1], respectively. 
     The power-supply control apparatus  400  of the storage battery system  300 - 1  obtains the charge-and-discharge plans and the additional information for the three time periods at the time k+1 that is the start time of the time period k′+1, and stores the charge-and-discharge plans and the additional information in, for example, the RAM  42 . 
     Although the storage battery system  300 - 1  is used as an example in the above descriptions of  FIG. 7 , charge-and-discharge plans and additional information are also delivered to other storage battery systems  300  at the start time of each time period in a similar manner. For each time period, the same additional information is delivered to all the storage battery systems  300 . 
     For example, at the time k, the following charge-and-discharge plans and additional information are delivered to the storage battery system  300 - 2 : a charge-and-discharge plan S 2 [k′|k] of the storage battery system  300 - 2 , the total increase σc[k′|k], and the total decrease σd[k′|k] for the time period k′; a charge-and-discharge plan S 2 [k′+1|k] of the storage battery system  300 - 2 , the total increase σc[k′+1|k], and the total decrease σd[k′+1|k] for the time period k′+1; and a charge-and-discharge plan S 2 [k′+2|k] of the storage battery system  300 - 2 , the total increase σc[k′+2|k], and the total decrease σd[k′+2|k] for the time period k′+2. 
     Next, a charge-and-discharge plan is described with reference to  FIG. 8 .  FIG. 8  is a table illustrating an exemplary charge-and-discharge plan.  FIG. 8  illustrates a charge-and-discharge plan S 1 [k′|k] of the storage battery system  300 - 1  generated at the time k for the time period k′. 
     The charge-and-discharge plan S 1 [k′|k] indicates operations to be performed by the storage battery system  300 - 1  in the time period k′. In the example of  FIG. 8 , the charge-and-discharge plan S 1 [k′|k] indicates that the charging operation of the storage battery  500  is performed from the time k to time k+a, and the bypass operation is performed from the time k+a to the time k+1 that is the start time of the time period k′+1 (or the end time of the time period k′). 
     The power-supply control apparatus  400  performs charging and discharging of the storage battery  500  according to the charge-and-discharge plan S 1 [k′|k]. 
     Next, a total increase and a total decrease included in additional information of the present embodiment are described with reference to  FIGS. 9A and 9B .  FIGS. 9A and 9B  are graphs used to describe a total increase and a total decrease in power consumption.  FIG. 9A  illustrates increases and decreases in power consumption in time periods k′ through k′+2 that result when charge-and-discharge plans for the respective time periods are executed by all the storage battery systems  300  connected to the delivery server  200 . In  FIGS. 9A and 9B , the value “0” on the vertical axes corresponds to a case where the bypass operation is performed in all the storage battery systems  300 .  FIG. 9B  illustrates total increases and total decreases in power consumption in the respective time periods. 
     In  FIGS. 9A and 9B , it is assumed that storage battery systems  300 - 1  through  300 - 5  are connected to the delivery server  200 . 
     As illustrated by  FIG. 9A , in the time period k′, the amount of power supplied to each of the storage battery systems  300 - 1 ,  300 - 2 , and  300 - 3  increases, and the amount of power supplied to none of the storage battery systems  300  decreases. Thus, when the storage battery systems  300  perform the charge-and-discharge plans for the time period k′, the power consumption in the time period k′ becomes higher than power consumption in a case where all the storage battery systems  300  perform the bypass operation. 
     Similarly, in the time period k′+1, the amount of power supplied to each of the storage battery systems  300 - 4  and  300 - 5  increases, and the amount of power supplied to none of the storage battery systems  300  decreases. Thus, when the storage battery systems  300  perform the charge-and-discharge plans for the time period k′+1, the power consumption in the time period k′+1 becomes higher than power consumption in a case where all the storage battery systems  300  perform the bypass operation. 
     On the other hand, in the time period k′+2, when the storage battery systems  300  perform the charge-and-discharge plans for the time period k′+2, the power consumption becomes lower than power consumption in a case where all the storage battery systems  300  perform the bypass operation. 
     When charge-and-discharge plans for multiple time periods are to be delivered, the additional information calculator  233  of the delivery server  200  calculates, for the respective time periods, amounts increased and decreased from the power consumption at the start time of the first time period of the multiple time periods, and uses the calculated amounts as total increases and total decreases. 
     Total increases and total decreases in  FIG. 9B  indicate the amounts increased and decreased in the respective time periods from the power consumption at the start time k of the time period k′. 
     In the example of  FIG. 9B , in the time period k′, the total increase σc[k′|k] is 300 kWh and the total decrease σd[k′|k] is 0 kWh. In the time period k′+1, the total increase σc[k′+1|k] is 200 kWh and the total decrease σd[k′+1|k] is 0 kWh. In the time period k′+2, the total increase σc[k′+2|k] is 0 kWh and the total decrease σd[k′+2|k] is −500 kWh. 
     As described above, in the present embodiment, both an increase and a decrease in power consumption are calculated for each time period. Accordingly, the present embodiment makes it possible to detect a variation in the amount of power supplied to each storage battery system  300  even in a case where an increase and a decrease in power consumption are the same (i.e., offset each other) and as a result, the power consumption does not change. 
     Next, before descriptions of processes performed by apparatuses constituting the power-supply control system  100  of the present embodiment, symbols used in the descriptions of the processes are described. 
     In the present embodiment, p[l′|k] indicates a predictive power consumption value calculated at a time k for a time period l′, and S i [l′|m] indicates a charge-and-discharge plan of a storage battery system  300 - i  generated at a time m for the time period l′. Also, σc[l′|m] indicates a total increase and σd[l′|m] indicates a total decrease that result when all the storage battery systems  300  operate according to charge-and-discharge plans S i [l′|m]. 
     A corrected predictive power consumption value p − [l′|k,m] calculated by the prediction corrector  418  of the power-supply control apparatus  400  is represented by formula 1 below. 
     The corrected predictive power consumption value p − [l′|k,m] is a predictive value of power consumption in each time period that is predicted when all the storage battery systems  300  execute the charge-and-discharge plans S i [l′|m] stored in the RAM  42 . 
     
       
         
           
             
               
                 
                   
                     
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     In formula 1, k indicates the present time, and m indicates a past time before the time k. Also in formula 1, m′ indicates a time period from the time m. Thus, the corrected predictive power consumption value p − [l′|k,m] of the present embodiment is obtained by correcting a predictive power consumption value of the time period l′ calculated at the time k, by using a total increase and a total decrease in the time period l′ calculated at the time m before the time k. 
     Further in formula 1, H indicates the number of time periods for which charge-and-discharge plans S i [l′|m] are generated at the delivery server  200 , and is set in the delivery server  200  in advance. 
     Next, an exemplary process performed by the delivery server  200  of the present embodiment is described with reference to  FIG. 10 .  FIG. 10  is a flowchart illustrating an exemplary process performed by the delivery server  200 . 
     The delivery server  200  determines whether it is the time k that is the start time of the time period k′ (step S 101 ). When it is not the time k at step S 101 , the delivery server  200  waits until it becomes the time k. When it is the time k at step S 101 , the delivery server  200  obtains past power consumption values of past time periods from the power consumption database  220 , and also obtains climate information (step S 102 ). The climate information includes, for example, a temperature. 
     Next, the power consumption predictor  231  of the delivery server  200  calculates predictive power consumption values for H time periods from the time period k′ using the past power consumption values and the climate information (step S 103 ). Next, the charge-and-discharge plan generator  232  of the delivery server  200  generates charge-and-discharge plans of the storage battery systems  300  for the H time periods based on remaining-amount data of the storage batteries  500  stored in the remaining amount database  210  and the predictive power consumption values calculated at step S 103  (step S 104 ). 
     Next, the additional information calculator  233  of the delivery server  200  calculates additional information including a total increase and a total decrease for each time period (step S 105 ). 
     Then, the delivery server  200  adds a time stamp to the charge-and-discharge plans and the additional information for the H time periods, delivers the charge-and-discharge plans and the additional information to the storage battery systems  300 , and ends the process. 
     The delivery server  200  performs the above process at the start time of every time period. 
     Next, an exemplary process performed by the power-supply control apparatus  400  of the present embodiment is described with reference to  FIGS. 11 and 12 .  FIG. 11  is a flowchart illustrating an exemplary process performed by the power-supply control apparatus  400 . 
     The input receiver  411  of the power-supply control apparatus  400  determines whether latest charge-and-discharge plans and additional information for H time periods have been received (step S 1101 ). 
     When it is determined at step S 1101  that the latest charge-and-discharge plans and additional information have been received, the power-supply control apparatus  400  stores the received charge-and-discharge plans and additional information in a memory such as the RAM  42  (step S 1102 ). In this exemplary process, it is assumed that charge-and-discharge plans {S i [l′|k]} l′−k′˜k′+H−1  generated at the time k for the time periods k′ through k′+H−1 have been received at step S 1101 . Also in this exemplary process, it is assumed that the additional information received at step S 1101  includes total increases {σc[l′|k]} l′=k′˜k′+H−1  and total decreases {σd[l′|k]} l′=k′˜k′+H−1  calculated at the time k for the time periods l′ through l′+H−1. Here, the time k indicates the current time (the present time). 
     Next, in the time period k′, the power supply controller  414  of the power-supply control apparatus  400  performs one of the charging operation of the storage battery  500 , the discharging operation of the storage battery  500 , and the bypass operation according to the received charge-and-discharge plan S i [k′|k] (step S 1103 ). Next, the storage battery monitor  413  of the power-supply control apparatus  400  obtains remaining-amount data of the storage battery  500 , and adds a time stamp to the remaining-amount data (step S 1104 ). Then, the communicator  412  of the power-supply control apparatus  400  sends the remaining-amount data with the time stamp to the delivery server  200  (step S 1105 ), and the power-supply control apparatus  400  ends the process. 
     When it is determined at step S 1101  that the latest charge-and-discharge plans and additional information have not been received, the power consumption predictor  416  of the power-supply control apparatus  400  calculates predictive power consumption values (step S 1106 ). In this exemplary process, it is assumed that the power consumption predictor  416  calculates predictive power consumption values {p[l′|k]} l′=k′˜k′−H−1  for the time periods k′ through k′+H−1 at the time k. The predictive power consumption values may be calculated at step S 1106  according to a known algorithm. 
     Next, the plan presence determiner  415  of the power-supply control apparatus  400  determines whether a previously-received charge-and-discharge plan and additional information are stored in a memory (step S 1107 ). 
     More specifically, assuming that ks indicates the time when previously-received charge-and-discharge plans were generated, the plan presence determiner  415  determines whether a charge-and-discharge plan S i [k′|ks] generated at the time ks for the time period k′ exists in the memory. Also, the plan presence determiner  415  determines whether a total increase σc[k′|ks] and a total decrease σd[k′|ks] generated at the time ks for the time period k′ exist in the memory. 
     In other words, at step S 1107 , when ks′ indicates a time period that starts at the time ks before the time k, the plan presence determiner  415  determines whether k′≤ks′+H−1 is satisfied. That is, the plan presence determiner  415  determines whether the time period k′ is included in H time periods from the time period ks′. 
     When it is determined at step S 1107  that the previously-received charge-and-discharge plan and additional information are stored in the memory, the power-supply control apparatus  400  proceeds to step S 1201  of  FIG. 12 . 
     When it is determined at step S 1107  that the previously-received charge-and-discharge plan and additional information are not stored in the memory, the first peak determiner  417  of the power-supply control apparatus  400  determines whether a peak of the predictive power consumption values calculated at step S 1106  is in the nearest time period k′ (step S 1108 ). In other words, based on past power consumption values and the predictive power consumption values {p[l′|k]} l′=k′˜k′+H−1  calculated at the time k for the time periods k′ through k′+H−1, the first peak determiner  417  determines whether the predictive power consumption value of the nearest time period k′ is largest. The power-supply control apparatus  400  of the present embodiment preferably stores actual power consumption values detected in the past in a memory. 
     When it is determined at step S 1108  that the peak is in the time period k′, the power supply controller  414  of the power-supply control apparatus  400  prevents the charging operation of the storage battery  500 , performs the discharging operation of the storage battery  500  if the storage battery  500  can discharge electricity (step S 1109 ), and proceeds to step S 1104 . 
     When it is determined at step S 1108  that the peak is not in the time period k′, the power supply controller  414  of the power-supply control apparatus  400  performs the bypass operation (step S 1110 ), and proceeds to step S 1104 . 
     As described above, when no previously-delivered charge-and-discharge plan is stored in the memory, the power-supply control apparatus  400  calculates latest predictive power consumption values and determines whether a peak of power consumption exists in the nearest time period. When the peak of power consumption exists in the nearest time period, the power-supply control apparatus  400  prevents the storage battery  500  from being charged and causes the storage battery  500  to discharge electricity if possible. Thus, in the present embodiment, the amount of power to be used to charge the storage battery  500  is saved by preventing charging the storage battery  500 , and the storage battery  500  is caused to discharge electricity if possible. Accordingly, the present embodiment makes it possible to reduce power consumption in a time period where a peak of predictive power consumption values exists. 
       FIG. 12  is another flowchart illustrating an exemplary process performed by the power-supply control apparatus  400 . When it is determined at step S 1107  of  FIG. 11  that the previously-received charge-and-discharge plan and additional information are stored in the memory, the power-supply control apparatus  400  proceeds to step S 1201  of  FIG. 12 . 
     Because step S 1201  of  FIG. 12  is substantially the same as step S 1108  of  FIG. 11 , its description is omitted here. 
     When it is determined at step S 1201  that the peak of the predictive power consumption values is in the time period k′, the increase determiner  420  of the power-supply control apparatus  400  determines whether the total increase σc[k′|ks] of the time period k′ stored in the memory is 0 (step S 1202 ). In other words, the increase determiner  420  determines whether the charging operation is planned in the time period k′. 
     When it is determined at step S 1202  that the total increase σc[k′|ks] is 0, the power-supply control apparatus  400  proceeds to step S 1103  of  FIG. 11 . When the total increase σc[k′|ks] is 0, the charge-and-discharge plan S i [k′|ks] generated at the time ks for the time period k′ will not increase peak power or cause a new peak in the time period k′, and is therefore considered appropriate. Therefore, the power-supply control apparatus  400  proceeds to step S 1103  of  FIG. 11 , and executes the charge-and-discharge plan S i [k′|ks] generated at the time ks for the time period k′. 
     When it is determined at step S 1202  that the total increase σc[k′|ks] is not 0, the power-supply control apparatus  400  proceeds to step S 1109  of  FIG. 11 . When the total increase σc[k′|ks] is not 0, the charge-and-discharge plan S i [k′|ks] generated at the time ks for the time period k′ will increase power consumption in the nearest time period k′. Therefore, the power-supply control apparatus  400  proceeds to step S 1109  of  FIG. 11 , and prevents the charging operation of the storage battery  500 . 
     When it is determined at step S 1201  that the peak of the predictive power consumption values is not in the time period k′, the prediction corrector  418  of the power-supply control apparatus  400  calculates corrected predictive power consumption values {p − [l′|k,ks]} l′=k′˜k′+H−1  based on the predictive power consumption values of the respective time periods calculated at step S 1106 , and total increases and total decreases stored in the memory (step S 1203 ). 
     As described above, at step S 1106 , the predictive power consumption values {p[l′|k]} l′=k′˜k′+H−1  are calculated at the time k for the time periods k′ through k′+H−1. Also, it is assumed that total increases {σc[l′|ks]} l′=ks′˜ks′+H−1  calculated at the time ks for the time periods ks′ through ks′+H−1 are stored in the memory. Further, it is assumed that total decreases {σd[l′|ks]} l′=ks′˜ks′+H−1  calculated at the time ks for the time periods ks′ through ks′+H−1 are stored in the memory. A time period l′ is included in the time periods ks′ through ks′+H−1. 
     Thus, at step S 1203 , the corrected predictive power consumption values {p − [l′|k,ks]} l′=k′˜k′+H−1  are obtained by correcting the predictive power consumption values of the respective time periods calculated at the time k, by using the total increases and the total decreases of the respective time periods calculated at the time ks before the time k. 
     Next, based on the corrected predictive power consumption values {p − [l′|k,ks]} l′=k′˜k′+H−1  for the time periods k′ through k′+H−1, the second peak determiner  419  of the power-supply control apparatus  400  determines whether a peak of the corrected predictive power consumption values is in the nearest time period k′ (step S 1204 ). 
     When it is determined at step S 1204  that the peak of the corrected predictive power consumption values is not in the time period k′, the power-supply control apparatus  400  proceeds to step S 1103  of  FIG. 11 . 
     When it is determined at step S 1204  that the peak of the corrected predictive power consumption values is in the time period k′, the increase determiner  420  of the power-supply control apparatus  400  determines whether the total increase σc[k′|ks] of the time period k′ stored in the memory is 0 (step S 1205 ). 
     When it is determined at step S 1205  that the total increase σc[k′|ks] is 0, the power-supply control apparatus  400  proceeds to step S 1103  of  FIG. 11 . 
     When it is determined at step S 1205  that the total increase σc[k′|ks] is not 0, the power-supply control apparatus  400  proceeds to step S 1110  of  FIG. 11 . 
     Here, NO at step S 1205  indicates that it is expected that power consumption peaks and further increases in the nearest time period k′ when the power consumption in the time period k′ is predicted taking into account an increase and a decrease in power consumption caused by executing the charge-and-discharge plan in the memory. In other words, NO at step S 1205  indicates a case where the current power usage status is different from the power usage status at the time ks when the charge-and-discharge plan was generated, and a problem such as an increase in peak power or an occurrence of a new peak may be caused when the charge-and-discharge plan stored in the memory is executed. 
     Thus, the power-supply control apparatus  400  of the storage battery system  300  of the present embodiment is configured to detect conditions that may cause a problem as described above and perform the bypass operation without executing a charge-and-discharge plan when such conditions are detected. This configuration makes it possible to reliably control a power supply even when the latest charge-and-discharge plan is not delivered. 
     Effects of the present embodiment are described below with reference to  FIGS. 13A through 14C .  FIGS. 13A through 13C  are graphs used to describe effects of the power-supply control system  100 . 
       FIG. 13A  illustrates predictive power consumption values calculated at the time ks for the time periods ks′ through ks′+5.  FIG. 13B  illustrates charge-and-discharge plans generated at the time ks for the time periods ks′ through ks′+5.  FIG. 13C  illustrates predictive power consumption values for the time periods ks′ through ks′+5 that are predicted when the charge-and-discharge plans generated at the time ks are executed. 
     As indicated by  FIG. 13A , in the predictive power consumption values for the time periods ks′ through ks′+5, the predictive power consumption value for the time period ks′+1 is smallest, and the predictive power consumption value for the time period ks′+3 is largest. 
     According to the charge-and-discharge plans of  FIG. 13B , the total increase σc[ks′|ks] in the time period ks′ is 0 kWh, the total increase σc[ks′+1|ks] in the time period ks′+1 is 300 kWh, and the total increase σc[ks′+2|ks] in the time period ks′+2 is 200 kWh. Also, the total decrease σd[ks′+3|ks] in the time period ks′+3 is −500 kWh. 
     As indicated by  FIG. 13C , assuming that the charge-and-discharge plans are executed, the predictive power consumption value of the time period ks′+1 increases by 300 kWh, the predictive power consumption value of the time period ks′+2 increases by 200 kWh, and the predictive power consumption value of the time period ks′+3 decreases by 500 kWh. As a result, the power consumption in the time periods ks′ through ks′5 is leveled. 
     Next, an exemplary case where the latest charge-and-discharge plans and additional information at the current time are not delivered is described with reference to  FIGS. 14A through 14C . In this case, the power-supply control apparatus  400  controls charging and discharging of the storage battery  500  using the charge-and-discharge plans and additional information for the time periods ks′ through ks′+5 stored in the memory. 
     Here, it is assumed that the time k is the same as the time ks+1 that is the start time of the time period ks′+1. That is, the time period k′ of  FIGS. 14A through 14C  corresponds to the time period ks′+1 of  FIGS. 13A through 13C . 
       FIGS. 14A through 14C  are graphs used to describe effects of the power-supply control system  100 .  FIG. 14A  illustrates an actual power consumption value of the time period k′−1, and predictive power consumption values calculated at the time k for the time periods k′ through k′+5.  FIG. 14B  illustrates charge-and-discharge plans and additional information stored in a memory of the power-supply control apparatus  400 .  FIG. 14C  illustrates the actual power consumption value of the time period k′−1, and predictive power consumption values that are predicted when the charge-and-discharge plans stored in the memory are executed without change. 
     As indicated by  FIG. 14A , in the predictive power consumption values calculated at the time k, the predictive power consumption value for the time period k′ (the time period ks′+1 of  FIGS. 13A-13C ) is larger than the predictive power consumption value for the time period k′+1 (the time period ks′+2 of  FIGS. 13A-13C ). This indicates that the power usage status at the time k is different from the power usage status at the time ks. 
     In this case, when the charge-and-discharge plans stored in the memory are executed, the predictive power consumption value of the time period k′ increases to 4100 kWh and becomes a new peak. 
     Here, the total increase σc[k′|ks] (i.e., the total increase σc[ks′+1|ks]) of the time period k′ is 300 kWh and the total decrease σd[k′|k] is 0 kWh, and is not 0 kWh. 
     For this reason, the power-supply control apparatus  400  of the present embodiment prevents the storage battery  500  from being charged in the time period k′ and performs the bypass operation in order to reduce the total increase and thereby reduce the power consumption in the time period k′. Thus, the present embodiment makes it possible to prevent an occurrence of a new peak. 
     Next, an exemplary process performed by the power-supply control apparatus  400  to change a charge-and-discharge plan is described with reference to  FIG. 15 .  FIG. 15  is a drawing illustrating a change made to a charge-and-discharge plan. 
       FIG. 15  illustrates a charge-and-discharge plan for the time period k′ generated at the time ks and a charge-and-discharge plan for the time period k′ changed (or corrected) at the time k. 
     When charge-and-discharge plans are not delivered at the current time k, and it is determined that the predictive power consumption value of the nearest time period k′ becomes a peak if a charge-and-discharge plan of the time period k′ stored in the memory is executed, the power-supply control apparatus  400  may be configured to change the charge-and-discharge plan. 
     In the example of  FIG. 15 , the power-supply control apparatus  400  changes the charging operation in the charge-and-discharge plan generated at the time ks to the bypass operation. 
     As described above, based on a previously-generated charge-and-discharge plan and additional information stored in the memory, the power-supply control apparatus  400  of the present embodiment can change the previously-generated charge-and-discharge plan into a charge-and-discharge plan suitable for the current time, and can improve reliability in power-supply control. 
     According to the present embodiment, the delivery server  200  needs to send only charge-and-discharge plans and additional information to the storage battery systems  300  to improve reliability in power-supply control. This in turn eliminates the need for the delivery server  200  to send separate information to each of the storage battery systems  300 , and makes it possible to reduce communication loads. 
     Also in the present embodiment, the delivery server  200  delivers additional information including a total increase and a total decrease instead of delivering charge-and-discharge plans of all the storage battery systems  300  to each of the storage battery systems  300 . Thus, the present embodiment makes it possible to reduce the amount of data to be delivered by the delivery server  200 , and to reduce processing loads of the power-supply control apparatuses  400  of the storage battery systems  300 . 
     A storage battery is used in the present embodiment as an object whose charging and discharging operations are controlled. However, this disclosure may also be applied to other electric storage devices such as a capacitor and a flywheel energy storage. Further, this disclosure may also be applied to a heat storage tank for storing heat. In this case, heat transfer corresponds to power consumption in the present embodiment. 
     All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventors to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.