Patent Publication Number: US-2018041045-A1

Title: Regulating device control system, regulating device control method, and recording medium

Description:
TECHNICAL FIELD 
     The present invention relates to a regulating device control system, a regulating device control method, and a recording medium, and more particularly relates to a regulating device control system, a regulating device control method, and a recording medium for controlling a plurality of regulating devices for regulating the balance between electric power supply and demand in an electric power system. 
     BACKGROUND ART 
     Methods, which have been adopted for regulating the balance between power supply and demand in an electric power system, include a method for controlling the output of thermal power generation and a method of appropriately operating pumping-up hydraulic power generation while controlling the output of thermal power generation. 
     As renewable power sources such as photovoltaic or wind power generation, in which the amount of generated power depends on weather, are incorporated as distributed power sources in electric power systems in the future, concern arises that these distributed power sources may adversely affect the balance between power supply and demand. 
     A method of regulating power supply and demand that uses thermal power generation and pumping-up hydraulic power generation may by itself be inadequate to compensate for imbalance in power supply and demand that is brought about by the distributed power sources. As a result, a new method of regulating electric power supply and demand is now essential. 
     One method, which is thought to be a new method of regulating electric power supply and demand, employs apparatuses such as “storage cells,” “electric vehicles (EV),” and heat-pump water heaters (HP) (hereinbelow referred to as “electric power apparatuses”) that are linked to the power distribution network of an electric power system as regulating devices for regulating the balance between electric power supply and demand. 
     Patent Document 1 describes an electric power system control device that regulates the balance between electric power supply and demand by using consumer-side secondary batteries (ES), which are electric power apparatuses, as regulating devices for regulating the balance between electric power supply and demand. 
     LITERATURE OF THE PRIOR ART 
     Patent Documents 
     Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006-094648 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     The performance of a regulating device changes according to the conditions of use. 
     For example, deterioration of a regulating device progresses with use, and the performance of the regulating device worsens as the deterioration progresses. The degree of the progression of deterioration of a regulating device varies according to the amount of electric power regulated by the regulating device for regulating the balance between electric power supply and demand and the state of the regulating device (for example, the temperature). The change in the performance of the regulating device further depends on properties other than the deterioration of the regulating device. 
     A method is therefore to be desired for distributing electric power to a plurality of regulating devices that are used for regulating the balance between electric power supply and demand to reduce the amount of variability in the performance of the plurality of regulating devices. 
     It is an object of the present invention to provide a regulating device control system, regulating device control method, and recording medium that can solve the above-described problem. 
     Means for Solving the Problem 
     The regulating device control system according to the present invention is a regulating device control system that controls the operation of a plurality of regulating devices for regulating the balance between electric power supply and demand in an electric power system, and includes: 
     memory means that stores, for each of the regulating devices, correlation information that represents the correlation of the state of the regulating device, the amount of electric power allotted to the regulating device, and the amount of variability in the performance of the regulating device; 
     determination means that receives state information that indicates the state of each regulating device and electric power information that indicates the amount of regulated power necessary for the regulation of the balance between electric power supply and demand and, based on the correlation information, the state information, and the electric power information, determines the amount of electric power to be allotted to each of the regulating devices such that the total value of the amount of variability in the performance of each of the regulating devices is minimized under conditions in which the state of each of the regulating devices is the state indicated in the state information and the total value of the amount of electric power allotted to each of the regulating devices is the amount of regulated power; and 
     control means that controls the operation of each of the regulating devices based on the determination results of the determination means. 
     The regulating device control method according to the present invention is a regulating device control method in a regulating device control system that controls the operation of a plurality of regulating devices for regulating the balance between electric power supply and demand in an electric power system and includes: 
     for each of the regulating devices, storing in memory means: correlation information that indicates the correlation of the state of the regulating device, the amount of electric power to be allotted to the regulating device, and the amount of variability in the performance of the regulating device; 
     receiving state information that indicates the state of each regulating device and electric power information that indicates the amount of regulated power required for the regulation of the balance between the electric power supply and demand, and, based on the correlation information, the state information, and the electric power information, determining the amount of electric power to be allotted to each regulating devices such that the total value of the amount of variability in performance of each of the regulating devices is minimized under conditions in which the state of each of the regulating devices is the state indicated in the state information and the total value of the amount of electric power allotted to each of the regulating devices is the amount of regulated power; and 
     controlling the operation of each of the regulating devices based on the results of the determination. 
     The recording medium according to the present invention is a recording medium that is readable by a computer and on which a program is recorded for causing a computer to execute: 
     a storage procedure of storing in memory means, for each of a plurality of regulating devices for regulating the balance between electric power supply and demand in an electric power system, correlation information that indicates the correlation of state information of the regulating device, the amount of electric power to be allotted to the regulating device, and the amount of variability in performance of the regulating device; 
     a determination procedure of receiving state information that indicates the state of each of the regulating devices and electric power information that indicates the amount of regulated power required for regulating the balance between the electric power supply and demand, and, based on the correlation information, the state information, and the electric power information, determining the amount of electric power to be allotted to each of the regulating devices such that the total value of the amount of variability in performance of each of the regulating devices is minimized under conditions in which the state of each of the regulating devices is the state indicated in the state information and the total value of the amount of electric power allotted to each of the regulating devices is the amount of regulated power; and 
     a control procedure of controlling the operation of each of the regulating devices based on the results of the determination. 
     Effect of the Invention 
     According to the present invention, variability in the performance of a plurality of regulating devices that are used for regulating the balance between electric power supply and demand can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an electric power control system that adopts the regulating device control system of the first exemplary embodiment of the present invention. 
         FIG. 2  shows an example of the value of D k  when temperature T 0  is 15, 20, and 25 degrees. 
         FIG. 3  is a sequence diagram for describing the operation of the electric power control system. 
         FIG. 4  shows cell management unit  5  that is made up of storage unit  52 , determination unit  53 , and control unit  54 . 
         FIG. 5  shows an electric power control system that adopts the regulating device control system of the second exemplary embodiment of the present invention. 
         FIG. 6  shows an example of the value of D k  when temperature SoC 0  is 0.5, 0.6, and 0.7. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Exemplary embodiments of the present invention are next described with reference to the accompanying drawings. 
     First Exemplary Embodiment 
       FIG. 1  shows an electric power control system that adopts the regulating device control system of the first exemplary embodiment of the present invention. 
     In  FIG. 1 , the electric power control system includes: electric power system  1 , power line  2 , storage cell systems  31 - 3   n  (where n is an integer equal to or greater than 2), EMU (Energy Management Unit)  4 , and cell management unit  5 . 
     Electric power system  1  is a system for supplying electric power to consumers, and for example, includes a power plant such as a thermal power plant, a renewable power source, and a transformer. Electric power system  1  supplies the generated electric power from the power plant or renewable power source to power line  2  by way of the transformer. Typically, power line  2  is included in electric power system  1 , but in  FIG. 1 , electric power system  1  and power line  2  are shown separately in the interest of simplifying the explanation. 
     Storage cell systems  31 - 3   n  are used for regulating the balance between electric power supply and demand in electric power system  1 . For example, storage cell systems  31 - 3   n  are each managed by consumers. A number of storage cell systems  31 - 3   n  may also be managed on the electric power supply side. 
     Each of storage cell systems  31 - 3   n  includes: communication unit  301 , ES (Energy storage)  302 , inverter  303 , BMU (Battery Management Unit)  304 , and temperature detectors  304   a  and  304   b.  Regarding communication unit  301 , ES  302 , inverter  303 , BMU  304 , and temperature detectors  304   a  and  304   b,    FIG. 1  shows the components in storage cell system  31 . 
     Communication unit  301 , ES  302 , inverter  303 , BMU  304 , and temperature detectors  304   a  and  304   b  in storage cell system  31  are next described. 
     Communication unit  301  communicates with cell management unit  5 . 
     ES  302  is one example of the regulating device. 
     ES  302  is, for example, a stationary battery or a secondary battery in an electric vehicle. ES  302  is, for example, a lithium-ion secondary battery. ES  302  is not limited to a lithium-ion secondary battery and may be any type of storage cell. 
     Inverter  303  converts alternating-current voltage from power line  2  to direct-current voltage during charging of ES  302  and thus charges ES  302  by this direct-current voltage. During discharging of ES  302 , inverter  303  converts the direct-current voltage from ES  302  to alternating-current voltage and supplies this alternating-current voltage to power line  2  to thus discharge ES  302 . 
     BMU  304  controls inverter  303  in accordance with operation instructions from cell management unit  5  to control the charging and discharging of ES  302 . 
     In addition, BMU  304  transmits to cell management unit  5  by way of communication unit  301  the detection results of temperature detector  304   a  that detects the temperature To of ES  302  and the detection results of temperature detector  304   b  that detects the ambient temperature T E  (the temperature of the environment in which ES  302  is placed) of ES  302 . 
     Still further, BMU  304  calculates and manages the amount of reduction of the capacity D total,k  from the initialization of ES  302  in storage cell system  31 . BMU  304  transmits the amount of reduction of capacity D total,k  to cell management unit  5  by way of communication unit  301 . The method of calculating the amount of reduction of capacity D total,k  from the initialization of ES  302  is known technology, and a detailed explanation is therefore here omitted. 
     The temperature T 0  of ES  302 , the ambient temperature T E  of ES  302 , and the amount of reduction of capacity D total,k  of ES  302  are examples of the state of ES  302 . 
     An explanation regarding communication unit  301 , ES  302 , inverter  303 , BMU  304 , and temperature detectors  304   a  and  304   b  in each storage cell system other than storage cell system  31  (hereinbelow referred to as “storage cell system  3   a ”) may be derived by merely changing the words “storage cell system  31 ” to “storage cell system  3   a ” in the explanation regarding communication unit  301 , ES  302 , inverter  303 , BMU  304 , and temperature detectors  304   a  and  304   b  in storage cell system  31  described above. 
     EMU  4  calculates the amount of regulated power P t  that is required for regulation of the balance between electric power supply and demand. For example, when there is a portion that exceeds the reference threshold value that is the standard for judging the presence or absence of a peak-cutting process (hereinbelow referred to as the “peak-cutting object portion”) on the future estimated total demand curve that has been provided or calculated in advance, EMU  4  calculates the amount of electric power that corresponds to this peak-cutting object portion as the amount of regulated power P t . 
     In the present exemplary embodiment, EMU  4  takes the value of the amount of regulated power P t  as a positive value when demand for electric power is necessary for regulating the balance between electric power supply and demand and takes the value of the amount of regulated power P t  as a negative value when supply of electric power is necessary for regulating the balance between electric power supply and demand. 
     EMU  4  transmits power information that indicates the amount of regulated power P t  to cell management unit  5 . 
     In the present exemplary embodiment, EMU  4  calculates the amount of regulated power P t  for the passage of each time interval Δt and transmits the power information that indicates the amount of regulated power P t  to cell management unit  5 . 
     Cell management unit  5  is one example of the regulating device control system. 
     Cell management unit  5  controls the operation of storage cell systems  31 - 3   n,  and further, the operation of each ES  302  to regulate the balance between electric power supply and demand in electric power system  1 . 
     Cell management unit  5  includes: communication unit  51 , storage unit  52 , determination unit  53 , and control unit  54 . 
     Communication unit  51  communicates with each of storage cell systems  31 - 3   n.    
     Communication unit  51  receives, for example, the detection results of the temperature T 0  of ES  302 , the detection results of the ambient temperature T E  of ES  302 , and the result of calculation of the amount of reduction of capacity D total,k  of ES  302  from each of storage cell systems  31 - 3   n  and supplies each of the detection results and calculation results to determination unit  53 . 
     Storage unit  52  is one example of the memory means. 
     Storage unit  52  stores for each of ES  302  within storage cell systems  31 - 3   n  correlation information that indicates the correlation of the state of ES  302 , the amount of electric power allotted to ES  302 , and the amount of variability in deterioration of ES  302 . The amount of change in deterioration of ES  302  is one example of the amount of variability in the performance of ES  302 . 
     For example, storage unit  52  stores the following Formula (1) as the correlation information for each ES  302  within storage cell systems  31 - 3   n.    
       Formula 1 
       amount of change in deterioration= D   k ( P   k   , x   k )  (1)
 
     Here, k=1−n 
     The amount of change in deterioration indicates the amount of change in deterioration of ES  302  within storage cell system k. 
     P k  indicates the amount of electric power (W) managed by ES  302  within storage cell system k, i.e., the amount of electric power (W) that is assigned to ES  302  within storage cell system k. 
     x k  represents the state of ES  302  within storage cell system k (in the present exemplary embodiment, temperature T 0  of ES  302  in storage cell system k, ambient temperature T E  of ES  302  in storage cell system k, and the amount of reduction of capacity D total,k  of ES  302  in storage cell system k). 
     D k (P k , x k ) represents the amount of the reduction of capacity when ES  302  in storage cell system k is used for a time interval Δt under conditions in which ES  302  in storage cell system k is in state x k  and ES  302  in storage cell system k is allotted an amount of electric power P k , i.e., D k (P k , x k ) represents the amount of change in the deterioration of ES  302  in storage cell system k. 
     In addition, storage unit  52  stores the minimum value P min,k  and maximum value P max,k  of the amount of charging/discharging of ES  302  for each ES  302  within storage cell systems  31 - 3   n.    
     When temperature is the overriding factor among causes of the reduction of capacity of ES  302  within storage cell system k, D k  follows the Arrhenius law and the square root law, whereby D k  can be approximately represented as in the following Formula (2): 
     
       
         
           
             
               
                 
                   
                     
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     where a 1,k  and a 2,k  are constants relating to deterioration inherent to ES  302  within storage cell system k. 
     The function T k (P k ,T 0 , T E ,t) in Formula (2) is a formula that represents the change in temperature of ES  302  in storage cell system k and is a function that gives the temperature at time t where time  0  is the current time, temperature T 0  is the current temperature of ES  302 , and temperature T E  is the current ambient temperature of ES  302 . For example, the function T k (P k , T 0 , T E ,t) can be represented as in the following Formula (3): 
       Formula (3) 
         T   k ( P   k   , T   0   , T   E   , t )=( T   0   −T   E   +a   3,k   P )exp( ta   4,k )− a   3,k   P+T   E   (3)
 
     where a 3,k  and a 4,k  are constants relating to the deterioration inherent to ES  302  in storage cell system k. 
     In Formula (2), the values corresponding to x k  of Formula (1) are T 0 , T E , and D total,k , and a 1,k , a 2,k , and a 4,k  in Formula (2) and Formula (3) are constants. 
       FIG. 2  shows an example of the values of D k  when temperature T 0  is 15, 20, and 25 degrees. 
     In addition, D k  is not limited to values specified in Formula (2) and Formula (3) and can be modified as appropriate. 
     In the present exemplary embodiment, storage unit  52  stores Formula (2) and Formula (3) as correlation information for each ES  302  in storage cell systems  31 - 3   n.    
     Determination unit  53  is one example of the determination means. 
     Determination unit  53  receives the detection results of temperature T 0  of each ES  302 , the detection results of ambient temperature T E  of each ES  302 , the calculation results of the amount of reduction of capacity D total,k  of each ES  302 , and electric power information that indicates the amount of regulated power P t . The detection results of temperature T 0  of each ES  302 , the detection results of ambient temperature T E  of each ES  302 , and the calculation results of the amount of reduction of capacity D total,k  of each ES  302  are examples of state information. 
     Determination unit  53  determines the amount of electric power P t  to be allotted to each ES  302  based on the detection results of temperature T 0  of each ES  302 , the detection results of ambient temperature T E  of each ES  302 , the calculation results of the amount of reduction of capacity D total,k  of each ES  302 , the correlation information in storage unit  52 , and electric power information that indicates the amount of regulated electric power P t  so as to minimize the amount of increase of the deterioration of each ES  302  that is caused by the use of each ES  302  in the regulation of the balance between electric power supply and demand. 
     In the present exemplary embodiment, determination unit  53  determines the amount of electric power P k  that is to be allotted to each ES  302  based on the detection results of temperature T 0  of each ES  302 , the detection results of ambient temperature T E  of each ES  302 , the calculation results of the amount of reduction of capacity D total,k  of each ES  302 , the correlation information in storage unit  52 , and the electric power information that indicates the amount of regulated power P t  such that the total value of the amount of change in deterioration D k  of each ES  302  is minimized under conditions in which the state of each ES  302  is the state notified from each storage cell system (the detection results of temperature T 0  of each ES  302 , the detection results of ambient temperature T E  of each ES  302 , and the calculation results of the amount of reduction of capacity D total,k  of each ES  302 ) and the total value of the amount of electric power allotted to each ES  302  is the amount of regulated power P t . 
     When the state of each ES  302  has not been reported from each storage cell system, determination unit  53  estimates the state of each ES  302  by means of the correlation information that is maintained in storage unit  52 . Determination unit  53  then determines the amount of electric power P k  to be allotted to each ES  302  based on the estimated state of each ES  302 , the correlation information in storage unit  52 , and the electric power information that indicates the amount of regulated power P t , similar to a case in which the states have been reported. For example, determination unit  53  is able to estimate the current temperature of each ES  302  by substituting into Formula (3) detection results of the temperatures of each ES  302  that were received in the past, detection results of ambient temperatures of each ES  302  that were received in the past, calculation results of the amount of reduction of capacity that were received in the past, and the amount of regulated power that was transmitted by way of control unit  54  in the past, is able to estimate the amount of change up to the present time of the amount of reduction of capacity by substituting these values into Formula (2), and is able to estimate the current amount of deterioration of capacity of each ES  302  by adding this value to the amounts of reduction of capacity of each ES  302  that were received in the past. 
     Even in a case in which the state of each ES  302  has been reported from each storage cell system, an improvement of the accuracy of the correlation information may be achieved if determination unit  53  estimates the state of each ES  302  and then compares these estimated results with the reported states to amend the correlation information that is kept in storage unit  52 . 
     Examples of the state of each ES  302  notified to determination unit  53  from each storage cell system include, in addition to the detection results of temperature T 0  of each ES  302 , the detection results of the ambient temperature T E  of each ES  302 , and the calculation results of the amount of reduction of capacity D total,k  of each ES  302 : the internal impedance value of each ES  302 , the thickness of each ES  302 , the volume of each ES  302 , the internal pressure of each ES  302 , the number of charge/discharge cycles up to the current time of each ES  302 , the cross-terminal voltage of each ES  302 , and the SoC value of each ES  302  that is shown in the second exemplary embodiment to be described later. 
     Control unit  54  is one example of control means. 
     Control unit  54  controls the operation of each ES  302  based on the determination results of determination unit  53 . In the present exemplary embodiment, control unit  54  transmits to each of storage cell systems  31 - 3   n  operation instructions indicating electric power P k  that is to be allotted to each ES  302  that was determined by determination unit  53 . 
     The operation is next described. 
       FIG. 3  is a sequence diagram for describing the operation of an electric power control system. In  FIG. 3 , only storage cell system  3   c  among storage cell systems  31 - 3   n  is shown in the interest of simplifying the explanation. 
     When EMU  4  calculates the amount of regulated power P t  and transmits electric power information indicating the amount of regulated power Pt to cell management unit  5  (Step S 301 ), determination unit  53  in cell management unit  5  receives the electric power information. 
     Upon receiving the electric power information, determination unit  53  transmits a request to report state (hereinbelow referred to as a “state report request”) to each of storage cell systems  31 - 3   n  by way of communication unit  51  (Step S 302 ). 
     In each of storage cell systems  31 - 3   n,  upon receiving the state report request by way of communication unit  301 , BMU  304  transmits the detection results of temperature detector  304   a  (the temperature T 0  of ES  302 ), the detection results of temperature detector  304   b  (the ambient temperature T E  of ES  302 ), and the calculation results of the amount of reduction of capacity D total,k  of ES  302  as state reports to cell management unit  5  by way of communication unit  301  (Step S 303 ). 
     In cell management unit  5 , upon receiving the state reports from each of storage cell systems  31 - 3   n,  determination unit  53  executes an operation to determine the amount of electric power P k  to be allotted to each ES  302  (Step S 304 ). 
     In the present exemplary embodiment, determination unit  53  in Step S 304  determines the amount of electric power P k  to be allotted to each ES  302  that simultaneously satisfies the following Formula (4), Formula (5), and Formula (6). 
       Formula (4) 
         P   t −Σ k=1   N   P   k =0  Formula (4)
 
       Formula (5) 
         P   min,k   ≦P   k   ≦P   max,k   Formula (5)
 
       Formula (6) 
       Σ k=1   N   D   k ( P   k   , x   k )→min  Formula (6)
 
     For example, determination unit  53  finds a plurality of sets of electric power amounts P 1 -P n  of each ES  302  in storage cell systems  31 - 3   n  that satisfy Formula (4) and Formula (5), finds the total value of D k  for each set, and then determines the sets of the amounts of electric power P 1 -P n  for which the total values of D k  are a minimum as the electric power amounts P 1 -P n  that are to be allotted to each ES  302  in storage cell systems  31 - 3   n.    
     For example, in some cases determination unit  53  gives values of P 1 -P n  such that dD k /dP k , which are the values obtained by differentiating D k  by each P k , are identical, with the exception of cases in which the values of P 1 -P n  are amounts of electric power where P k =P min,k  or P k =P min,k . 
     Determination unit  53 , upon determining the amounts of electric power P 1 -P n  that are allotted to each ES  302  in storage cell systems  31 - 3   n,  supplies these determination results to control unit  54 . 
     Control unit  54 , upon receiving the determination results of determination unit  53 , transmits by way of communication unit  51  operation instructions indicating the amounts of electric power that were determined for ES  302  within the storage cell system for each of storage cell systems  31 - 3   n  (Step S 305 ). 
     In each of storage cell systems  31 - 3   n,  BMU  304 , upon receiving the operation instructions by way of communication unit  301 , uses inverter  303  to charge ES  302  by the amount of electric power indicated in the operation instruction when the amount of electric power indicated in the operation instruction is a positive value (Step S 306 ). 
     On the other hand, when the amount of electric power indicated in the operation instruction is a negative value, BMU  304  uses inverter  303  to discharge the amount of electric power indicated in the operation instruction from ES  302  (Step S 306 ). 
     The effect of the present exemplary embodiment is next described. 
     According to the present exemplary embodiment, storage unit  52  stores for each ES  302  correlation information that indicates the correlation of the state of ES  302 , the amount of electric power allotted to ES  302 , and the amount of change in the performance of ES  302  (the amount of change in deterioration). 
     Determination unit  53  receives state information that indicates the state of each ES  302  and electric power information that indicates the amount of regulated power required for the regulation of the balance between electric power supply and demand. Determination unit  53 , based on the correlation information, the state information, and the electric power information, determines the amount of electric power that is to be allotted to each ES  302  such that the total value of the amount of change of performance (amount of change in deterioration) of each ES  302  is minimized under conditions in which the state of each ES  302  is the state indicated by the state information and the total value of the amount of electric power allotted to each ES  302  is the amount of regulated power. 
     Control unit  54  controls the operation of each ES  302  based on the determination results of determination unit  53 . 
     As a result, electric power can be assigned to a plurality of ES  302  such that variability in the performance of the plurality of ES  302  that are used for regulating the balance between electric power supply and demand is reduced. 
     The above-described effect is exhibited even by cell management unit  5  that is made up by storage unit  52 , determination unit  53 , and control unit  54 . 
       FIG. 4  shows cell management unit  5  that is made up of storage unit  52 , determination unit  53 , and control unit  54 . 
     In the present exemplary embodiment, the amount of deterioration of ES  302  was used as the amount of variability in the performance of ES  302 . 
     As a result, electric power can be assigned to a plurality of ES  302  such that the deterioration of the plurality of ES  302  that are used for regulating the balance between electric power supply and demand is reduced. 
     In the present exemplary embodiment, moreover, ES  302  (storage batteries) are used as the regulating devices for regulating the balance between electric power supply and demand in an electric power system, and the temperature of ES  302 , the ambient temperature of ES  302 , and the amount of reduction of capacity from the initialization of ES  302  are used as the states of the regulating devices. 
     Thus, when temperature in particular is taken as the overriding factor among the causes of the reduction (deterioration) of capacity of ES  302 , electric power can be assigned to a plurality of ES  302  such that the deterioration of the plurality of ES  302  is reduced. 
     In  FIG. 1 , determination unit  53  and control unit  54  were shown as separate apparatuses, but determination unit  53  may incorporate control unit  54 . 
     In  FIG. 1 , moreover, a regulating device control system that includes communication unit  51 , storage unit  52 , determination unit  53 , and control unit  54  is incorporated in cell management unit  5 , but all of communication unit  51 , storage unit  52 , determination unit  53 , and control unit  54  need not be incorporated in the same apparatus. 
     In the present exemplary embodiment, determination unit  53  acquires the state of each ES  302  after receiving electric power information that indicates the amount of regulated power, but determination unit  53  may also acquire the states of each ES  302  before receiving the electric power information. 
     Alternatively, determination unit  53  may repeat the operations of Steps S 302 , S 304 , and S 305  shown in  FIG. 3  within time intervals between receiving electric power information. 
     Cell management unit  5  may also be realized by a computer. In this case, the computer reads and executes a program that is recorded on a recording medium such as a CD-ROM (Compact Disk Read Only Memory) that can be read in a computer and then functions as communication unit  51 , storage unit  52 , determination unit  53 , and control unit  54 . The recording medium is not limited to a CD-ROM and can be modified as appropriate. 
     Second Exemplary Embodiment 
     The second exemplary embodiment of the present invention is next described. 
       FIG. 5  shows an electric power control system that adopts the regulating device control system of the second exemplary embodiment of the present invention. In  FIG. 5 , constructions that are identical to those shown in  FIG. 1  are given the same reference numbers. The following explanation focuses on points of the electric power control system shown in  FIG. 5  that differ from the electric power control system shown in  FIG. 1 . 
     Although the regulating device control system of the first exemplary embodiment used correlation information suited to a case in which temperature was the overriding factor among causes of the reduction (deterioration) of capacity of ES  302 , the regulating device control system of the second exemplary embodiment uses correlation information suited for a case in which the SoC (State of Charge) of ES  302  is the overriding factor as a cause of the reduction (deterioration) of the capacity of ES  302 . 
     In  FIG. 5 , each of storage cell systems  31 - 3   n  includes BMU  304 A in place of BMU  304  and leaves out temperature detectors  304   a  and  304   b;  and cell management unit  5  includes storage unit  52 A in place of storage unit  52  and includes determination unit  53 A in place of determination unit  53 . 
     BMU  304 A, similar to BMU  304 , controls inverter  303  in accordance with operation instructions from cell management unit  5  to control the charging and discharging of ES  302 . 
     In addition, BMU  304 A calculates and manages SoC 0 , which is the current SoC value of ES  302 , the current capacity C k  of ES  302 , and the amount of reduction of capacity D total,k  from the initialization of ES  302 . BMU  304 A transmits SoC 0  of ES  302 , the current capacity C k  of ES  302 , and the amount of reduction of capacity D total,k  from initialization of ES  302  to cell management unit  5  by way of communication unit  301 . 
     The techniques of computing SoC 0  of ES  302 , the current capacity C k  of ES  302 , and the amount of reduction of capacity D total,k  from the initialization of ES  302  are known technology and detailed explanation is therefore here omitted. 
     SoC 0  of ES  302 , the current capacity C k  of ES  302 , and the amount of reduction of capacity D total,k  from the initialization of ES  302  are examples of the state of ES  302 . 
     Storage unit  52 A is one example of the memory means. 
     Storage unit  52 A stores the following Formula (7) and Formula (8) as the above-described Formula (1). 
     
       
         
           
             
               
                 
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     Here, b 1,k  and b 2,k  are constants relating to deterioration inherent to ES  302  in storage cell system k. 
       Formula 8 
         V (SoC)= b   3,k SoC 3   +b   4,k SoC 2   +b   5,k SoC+ b   6,k    
     Here, b 3,k , b 4,k , and b 6,k  are constants relating to deterioration inherent to ES  302  in storage cell system k. 
     Function V(SoC) in Formula (7) is a formula that expresses the cross-terminal voltage of ES  302  in storage cell system k and that takes the value SoC as an argument. In addition, because we wish to know the cross-terminal voltage at time t in Formula (7), SoC value at time t=(SoC 0 +P k t/C k ) is taken as an argument. Formula (8) is a value obtained by, for example, approximating the function V(SoC) in Formula (7) by a polynomial. 
     In Formula (7), the values that correspond to x k  of Formula (1) are SoC 0 , C k , and D total,k : and b 1,k , b 2,k , b 3,k , and b 4,k , which are values representing the deterioration inherent to ES  302 , are constants. 
       FIG. 6  shows an example of the values of D k  when SoC 0  is 0.5, 0.6, and 0.7. 
     In addition, storage unit  52 A stores for each ES  302  in storage cell systems  31 - 3   n  the minimum value P min,k  and maximum value P max,k  of the amount of charging/discharging of ES  302 . 
     Determination unit  53 A is one example of the determination means. 
     Determination unit  53 A receives SoC 0  of each ES  302 , the current capacity C k  of each ES  302 , the amount of reduction of capacity D total,k  from initialization of each ES  302 , and electric power information that indicates the amount of regulated power P t . The SoC 0  of each ES  302 , the current capacity C k  of each ES  302 , and the amount of reduction of capacity D total,k  from initialization of each ES  302  are examples of state information. 
     Based on Formula (7) and Formula (8) in storage unit  52 A, SoC 0  of each ES  302 , the current capacity C k  of each ES  302 , the amount of reduction of capacity D total,k  from initialization of each ES  302 , and electric power information that indicates the amount of regulated power P t , determination unit  53 A determines the amount of electric power P k  to be allotted to each ES  302  that simultaneously satisfies the above-described Formula (4), Formula (5), and Formula (6). 
     Upon determining the amounts of electric power P 1 -P n  to be allotted to each ES  302  in storage cell systems  31 - 3   n,  determination unit  53 A supplies the determination results to control unit  54 . 
     Control unit  54 , upon receiving the determination results of determination unit  53 , transmits operation instructions indicating the amount of electric power that was determined to ES  302  in the storage cell system by way of communication unit  51 . 
     According to the present exemplary embodiment, ES  302  (storage cells) are used as regulating devices for regulating the balance between electric power supply and demand of an electric power system, and the SoC of ES  302 , the current capacity of ES  302 , and the amount of reduction of capacity from initialization of ES  302  are used as the states of the regulating devices. 
     As a result, when the SoC value has a particularly large effect in causing the reduction (deterioration) of capacity of ES  302 , electric power can be assigned to a plurality of ES  302  such that the deterioration of the plurality of ES  302  is reduced. 
     In  FIG. 5 , determination unit  53 A and control unit  54  are shown as separate components, but determination unit  53 A may incorporate control unit  54 . 
     In addition, although a regulating device control system that includes communication unit  51 , storage unit  52 A, determination unit  53 A, and control unit  54  is incorporated in cell management unit  5  in  FIG. 5 , all of communication unit  51 , storage unit  52 A, determination unit  53 A, and control unit  54  need not be incorporated in the same apparatus. 
     Cell management unit  5  shown in  FIG. 5  may be realized by a computer. In this case, the computer reads and executes a program that is recorded on a recording medium that can be read in the computer to function as communication unit  51 , storage unit  52 A, determination unit  53 A, and control unit  54 . 
     In each of the above-described exemplary embodiments, each ES  302  may be storage cells having mutually differing properties, or may be storage cells having identical properties. 
     In each of the above-described exemplary embodiments, EMU  4  may take the value of the amount of regulated power P t  as a negative value when demand for electric power is necessary for regulating the balance between electric power supply and demand, and may take the value of amount of regulated power P t  as a positive value when supply of electric power is necessary for regulating the balance between electric power supply and demand. In this case, when the amount of electric power indicated by an operation instruction is a negative value, BMU  304  uses inverter  303  to charge ES  302  with the amount of electric power indicated by the operation instruction. On the other hand, when the amount of electric power indicated by the operation instruction is a positive value, BMU  304  uses inverter  303  to discharge the amount of electric power indicated by the operation instruction from ES  302 . 
     In each of the above-described exemplary embodiments, the amount of change in the performance of ES  302  is not limited to the amount of change in deterioration of ES  302  and can be modified as appropriate. 
     In each of the above-described exemplary embodiments, the configurations shown in the drawings are merely examples and the present invention is not limited to these configurations. 
     Although the invention of the present application has been described with reference to each of the exemplary embodiments, the invention of the present application is not limited to the above-described exemplary embodiments. The configuration and details of the invention of the present application are open to various modifications within the scope of the invention of the present application that will be clear to one of ordinary skill in the art. This application claims the benefits of priority based on Japanese Patent Application No. 2012-041609 for which application was submitted on Feb. 28, 2012 and incorporates by citation all of the disclosures of that application. 
     EXPLANATION OF THE REFERENCE NUMBERS 
       1  electric power system 
       2  power line 
       31 - 3   n  storage cell system 
       301  communication unit 
       302  ES 
       303  inverter 
       304 ,  304 A BMU 
       304   a,    304   b  temperature detector 
       4  EMU 
       5  cell management unit 
       51  communication unit 
       52 ,  52 A storage unit 
       53 ,  53 A determination unit 
       54  control unit