Patent Publication Number: US-10784702-B2

Title: Battery control device, battery control system, battery control method,and recording medium

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/374,958, filed on Jul. 28, 2014, which is a National Stage Entry of International Application No. PCT/JP2014/052767, filed Feb. 6, 2014, which claims priority from Japanese Patent Application No. 2013-023211, filed Feb. 8, 2013. The entire contents of the above-referenced applications are expressly incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a battery control system, a battery control device, a battery control method and a program, and particularly relates to a battery control system, a battery control device, a battery control method and a program that control discharge or charge of a battery connected to a power system. 
     BACKGROUND ART 
     In a power system, as a method for adjusting power demand and supply, a method has been adopted, which mainly uses the output control function of thermal power generation equipment of a thermal electric power plant, and properly combines an output adjustment function of pumping-up hydraulic power generation. 
     However, if renewable power sources, which are typified by photovoltaic power generation and wind power generation where the power generation amount depends on weather conditions, are connected to the a power system as distributed power sources, there may arise the situation in which output variations of the distributed power sources cause a greater loss of balance between power demand and supply than in the related art. As a result, in order to compensate for a variation in the balance of power demand and supply that is caused by the distributed power sources, the only method that is likely to be insufficient is the method that adjusts the balance of power demand and supply by mainly using thermal power generation equipment, as in the related art. Therefore, in addition to the related art, a more effective technology for adjusting the balance between power supply and demand is needed. 
     As one technology that can address this need to adjust the power demand and supply balance, there is a promising technology that uses distributed energy storage (hereinafter, an energy storage will be called “ES”) such as “a storage battery” that interconnects to the distribution network of a power system, and is expected to come into widespread use from now on. 
     Patent Literature 1 describes a power system control method that adjusts power demand and supply by using a secondary battery (ES) in a consumer side. 
     In the power system control method described in Patent Literature 1, a power system control device acquires an amount of charge in a secondary battery, and further acquires a schedule of power supply to a power system that is generated based on a power demand forecast from a central power supply instruction office or the like. The power system control device determines an operation schedule of the secondary battery based on the amount of charge in the secondary battery and the power supply schedule. 
     When the power system control device determines the operation schedule of the secondary battery, the power system control device transmits the operation schedule to a secondary battery control system that controls the operation of the secondary battery. 
     When the secondary battery control system receives the operation schedule from the power system control device, the secondary battery control system controls charge and discharge of the secondary battery in accordance with the operation schedule, irrespective of the actual state of the power system. 
     Furthermore, Patent Literature 2 describes a system in which a central controller acquires state of charge information of a plurality of battery cells sampled at the same point of time via a local monitor and an upper controller. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: JP2006-94648A 
         Patent Literature 2: JP2010-146571A 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     The amount of power supplied from a renewable power source to a power system varies according to charges, over a short period of time, in the weather conditions. For example, in a photovoltaic power generation apparatus, the amount of power that is supplied varies as a result of small clouds that pass in front of the sun. 
     In practice, it is difficult to design a power supply schedule that can anticipate, over a short period of time, the degree of change in weather conditions. 
     Consequently, in the power system control method described in Patent Literature 1, it is difficult, in practice, to have the operation schedule (control information) of the secondary battery that is created by the power system control device that is an upper device, reflect chandes, in the amount of supplied power, that will occur due to changes, over a short period of time, in weather conditions. 
     Accordingly, the power system control method described in Patent Literature 1 has the problem of being unable to cope with the actual variation state of the power system, in which the control information from the upper device is not reflected. 
     As one method for solving the above problem, it is conceivable that the power system control device, which is an upper device, can provide an operation schedule to the secondary battery control system at cycle TA when the secondary battery control system controls charge and discharge a secondary battery at cycle TA, for example. 
     However, if the communication cycle of the power system control device and the secondary battery control system becomes short, the communication is easily influenced by communication trouble that occurs in the communication network between the power system control device and the secondary battery control system. As a result, making the operation schedule available to the secondary battery control system becomes difficult, and a problem occurs in which precise operation control of the secondary battery becomes low. 
     Nor is the above problem solved, by the system described in Patent Literature 2 that does not control charge and discharge of a battery cell. 
     An object of the present invention is to provide a battery control system, a battery control device, a battery control method and a program that can solve the above described problem. 
     Solution to Problem 
     A battery control device according to the present invention is a battery control device controlling an operation of a battery connected to a power system, the device includes:
         detection means that detects battery-related information that shows a state of the battery, or a state of an interconnection point of the power system and the battery;   first communication means that transmits a detection result of the detection means to an external device, and executes reception processing to receive operation control information to control the operation of the battery from the external device at a predetermined time interval; and   control means that executes battery operation control processing to control the operation of the battery based on a state of the power system and based on the operation control information received by the first communication means, at a time interval shorter than the predetermined time interval.       

     A battery control system according to the present invention is a battery control system including a first control device that controls an operation of a battery connected to a power system, and a second control device that communicates with the first control device, wherein
         the first control device includes:   detection means that detects battery-related information that shows a state of the battery or a state of an interconnection point of the power system and the battery,   first communication means that transmits a detection result of the detection means to the second control device, and executes reception processing to receive operation control information to control the operation of the battery from the second control device at a predetermined time interval, and   control means that executes battery operation control processing of controlling the operation of the battery based on a state of the power system and based on the operation control information received by the first communication means at a time interval shorter than the predetermined time interval, and   the second control device includes:   second communication means that communicates with the first control means, and receives the detection result of the detection means,   recognition means that recognizes a situation of the power system, and   processing means that generates the operation control information based on the detection result of detection means received by the second communication means, and based on the situation of the power system recognized by the recognition means, and transmits the operation control information from the second communication means to the first control device.       

     A battery control method according to the present invention is a battery control method that is performed by a battery control device that controls an operation of a battery connected to a power system, the method includes:
         detecting battery-related information that shows a state of the battery, or a state of an interconnection point of the power system and the battery;   transmitting the battery-related information to an external device, and executing reception processing to receive operation control information to control the operation of the battery from the external device at a predetermined time interval; and   executing battery operation control processing to control the operation of the battery based on a state of the power system and based on the operation control information at a time interval shorter than the predetermined time interval.       

     A battery control method according to the present invention is a battery control method that is performed by a battery control system including a first control device that controls an operation of a battery connected to a power system, and a second control device that communicates with the first control device,
         wherein the first control device detects battery-related information that shows a state of the battery, or a state of an interconnection point of the power system and the battery,   the first control device transmits the battery-related information to the second control device, and executes reception processing to receive operation control information to control the operation of the battery from the second control device at a predetermined time interval,   the first control device executes battery operation control processing to control the operation of the battery based on a state of the power system and based on the operation control information at a time interval shorter than the predetermined time interval,   the second control device receives the battery-related information from the first control device,   the second control device recognizes a situation of the power system, and   the second control device generates the operation control information, based on the battery-related information and based on the situation of the power system, and transmits the operation control information to the first control device.       

     A recording medium according to the present invention is a computer-readable recording medium recording a program for causing a computer to execute:
         a detection procedure of detecting battery-related information that shows a state of a battery connected to a power system, or a state of an interconnection point of the power system and the battery;   a communication procedure of transmitting the battery-related information to an external device, and executing reception processing to receive operation control information to control an operation of the battery from the external device at a predetermined time interval; and   a control procedure of executing battery operation control processing to control the operation of the battery, based on a state of the power system and based on the operation control information at a time interval shorter than the predetermined time interval.       

     Advantageous Effect of Invention 
     According to the present invention, the time interval at which the first control device (the battery control device) acquires the operation control information from the second control device (the external device) is longer than the operation time interval at which the first control device carries out the battery operation control processing control the operation of the battery by using the operation control information. Therefore, as compared with the case where the time interval, at which the first control device acquires the operation control information, is the operation time interval at which the first control device carries out the battery operation control processing or shorter, the processing to acquire the operation control information is less influenced by a communication trouble that is likely to occur between the first control device and the second control device. In addition, the first control device controls the operation of the battery based on the operation control information provided from the second control device and based on the state of the power system, and thereby it becomes possible to adjust the operation of the battery in response to an actual change in the state of the power system while following the operation control information. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram showing power control system  1000  that adopts a battery control system of a first exemplary embodiment of the present invention. 
         FIG. 2  is a diagram showing examples of local charge and discharge device  100 , storage battery SCADA  200  and power supply instruction section  300 A. 
         FIG. 3A  is a diagram showing an example of a storage battery distribution factor curve. 
         FIG. 3B  is a diagram showing an example of the storage battery distribution factor curve. 
         FIG. 4  is a diagram showing an example of a charge and discharge gain line. 
         FIG. 5  is a sequence diagram for explaining a P ES  derivation operation. 
         FIG. 6  is a sequence diagram for explaining a recognition operation. 
         FIG. 7  is a sequence diagram for explaining an allotment operation. 
         FIG. 8  is a diagram showing a local charge and discharge gain line. 
         FIG. 9  is a sequence diagram for explaining a charge and discharge control operation. 
         FIG. 10  is a diagram showing a local charge and discharge device including detector  101 , communicator  102  and arithmetic operation section  104 . 
         FIG. 11  is a diagram showing storage battery SCADA  200  including communicator  201 , recognition section  203  and arithmetic operation section  204 . 
         FIG. 12  is a diagram showing power control system  1000 A that adopts a battery control system of a second exemplary embodiment of the present invention. 
         FIG. 13  is a diagram showing an example of local charge and discharge device  100 A. 
         FIG. 14  is a diagram showing an example of sensor-incorporating switch slave station  700 A. 
         FIG. 15  is a diagram showing an example of ESMS  200 A. 
         FIG. 16  is a sequence diagram for explaining a setting operation. 
         FIG. 17  is a sequence diagram for explaining a generation operation. 
         FIG. 18  is a sequence diagram for explaining a power control operation. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. 
     First Exemplary Embodiment 
       FIG. 1  is a diagram showing power control system  1000  that adopts a battery control system of a first exemplary embodiment of the present invention. 
     In  FIG. 1 , power control system  1000  includes power system  1 , photovoltaic power generator  2 , N (N is an integer that is 1 or larger) power storage devices  3 , N local charge and discharge devices  100 , storage battery SCADA (Supervisory Control And Data Acquisition)  200 , and power supply instruction section  300 A in central power supply instruction office  300 . The power system  1  includes thermal power generation equipment  4 , distribution transformer  5  and distribution line  6 . Note that photovoltaic power generator  2  may be included in power system  1 . The battery control system includes N of local charge and discharge devices  100 , and storage battery SCADA  200 . 
     Power control system  1000  limits variation in system frequency that result from changes in the amount of power generated by photovoltaic power generator  2 , due to whether conditions, which is of concern to power system  1 , to which photovoltaic power generator  2  is interconnected, by controlling a power generation operation of thermal power generation equipment  4  and charge and discharge operations of N of power storage devices  3 . 
     Power system  1  is a system for supplying power to load  7  for use by consumers. Power system  1  also includes other devices (for example, a switch, an upper electric transformer, an SVR (Step Voltage Regulator) and a pole transformer), but for simplification of explanation, these devices are omitted. 
     Photovoltaic power generator  2  is an example of a renewable power source. The renewable power sources are not limited to a photovoltaic power generator and alternative renewable power sources can be used. For example, as the renewable power source, a wind power generator, a hydroelectric generator (including a small hydroelectric generator that generates power of 1,000 kilowatts or less), a geothermal power generator, or a power source in which these power generators coexist may be used. 
     Power storage device  3  is an example of a battery (a storage battery), and can be, for example, a lithium ion battery, a nickel-metal hydride battery, a sodium-sulfur battery, or a redox flow battery. 
     In the present exemplary embodiment, N power storage devices  3  are in one-to-one correspondence with N local charge and discharge devices  100 . Power storage device  3  may be contained in corresponding local charge and discharge device  100 , or does not have to be contained in corresponding local charge and discharge device  100 . In the present exemplary embodiment, respective power storage devices  3  are contained in corresponding local charge and discharge devices  100  (see  FIG. 2 ). 
     Respective local charge and discharge devices  100  control charge and discharge operations of corresponding power storage devices  3 . 
     Storage battery SCADA  200  manages respective local charge and discharge devices  100  and respective power storage devices  3 . 
     Power supply instruction section  300 A adjusts a power generation operation of thermal power generation equipment  4 , and charge and discharge operations of N of power storage devices  3 , and thereby limits a variation in the system frequency. 
       FIG. 2  is a diagram showing examples of local charge and discharge device  100 , storage battery SCADA  200  and power supply instruction section  300 A. In  FIG. 2 , those having the same configurations as those shown in  FIG. 1  are assigned with the same reference signs. In order to simplify explanation,  FIG. 2  shows one local charge and discharge device  100  containing one power storage device  3  among N of power storage devices  3  and N of local charge and discharge devices  100 . 
     First, local charge and discharge device  100  will be described. 
     Local charge and discharge device  100  is an example of a first control device or a battery control device. Local charge and discharge device  100  controls an operation of power storage device  3  that is connected to power system  1 . Local charge and discharge device  100  includes detector  101 , communicator  102 , frequency meter  103  and arithmetic operation section  104 . 
     Detector  101  is an example of first detection means (detection means). Detector  101  detects SOC (State of Charge) of power storage device  3 . The SOC of power storage device  3  takes a value within a range of 0 to 1. The SOC of power storage device  3  is an example of battery-related information that indicates a state of power storage device  3  or state information, or battery information for determining a chargeable and dischargeable capacity of power storage device  3 . Note that the battery-related information, the state information and the battery information are not limited to the SOC of power storage device  3  and alternative information can be used. For example, a cell temperature, a current amount and a voltage of power storage device  3  may be used. 
     Communicator  102  is an example of first communicating means. Communicator  102  communicates with storage battery SCADA  200 . 
     Frequency meter  103  is an example of second detection means. Frequency meter  103  detects a system frequency (a system frequency of power system  1 ). The system frequency varies in accordance with a power demand and supply balance state. The system frequency is an example of a state of the power system. Note that frequency meter  103  may be inside or outside local charge and discharge device  100 . 
     Arithmetic operation section  104  is an example of control means. 
     Arithmetic operation section  104  executes an information acquiring operation (transmission and reception processing) of obtaining allotment information that shows allotment for controlling the balance between power demand and supply from storage battery SCADA  200 , and a control operation (battery operation control processing) to control a charge and discharge operation of power storage device  3  by using the allotment information. 
     Note that the allotment information is information that relates to the charge and discharge operation of power storage device  3  and that is allotted to local charge and discharge device  100  and power storage device  3  in order to limit a variation in the system frequency. 
     Arithmetic operation section  104  repeatedly executes the information acquiring operation at time intervals, and repeatedly executes the control operation at time intervals shorter than the time intervals of the information acquiring operation. 
     For example, arithmetic operation section  104  repeatedly executes the information acquiring operation at periods T (for example, T=one minute), and repeatedly executes the control operation at periods T l  (for example, T l =0.1 seconds). Period T is an example of a predetermined time interval. 
     Note that period T and period T l  are not limited to one minute and 0.1 seconds, and period T can be longer than period T l . 
     Furthermore, both or any one of the operation time intervals of the information acquiring operation and the operation time interval of the control operation do not have to be fixed, and the shortest time among the respective operation time intervals of the information acquiring operation can be longer than the longest time among the respective operation time intervals of the control operation. 
     Furthermore, arithmetic operation section  104  may execute the information acquiring operation in response to the information request that requests SOC from storage battery SCADA  200 , or may autonomously execute the information acquiring operation. 
     Here, the information acquiring operation of arithmetic operation section  104  will be described. 
     Arithmetic operation section  104  transmits the SOC of power storage device  3  detected by detector  101  to storage battery SCADA  200  from communicator  102 , together with identification information (hereinafter, called “ID”) of power storage device  3 . 
     The ID is stored in each of local charge and discharge device  100  and storage battery SCADA  200 . Storage battery SCADA  200  identifies power storage device  3 , from which the SOC is reported, by using the ID transmitted with the SOC of power storage device  3 . 
     Communicator  102  transmits the SOC and ID of power storage device  3  to storage battery SCADA  200 , and thereafter receives allotment information from storage battery SCADA  200 . 
     The allotment information is set in accordance with SOC of power storage device  3  and an imbalanced state of power demand and supply. In the present exemplary embodiment, as the allotment information, allotment coefficient K and maximum value Δf max  of integral values of frequency deviations are used. Allotment coefficient K becomes larger as the allotment ratio to power storage device  3  becomes higher. Maximum value Δ fmax  of the integral values of the frequency deviations is used as a threshold value of the deviation amount of the system frequency with respect to the reference frequency (for example, 50 Hz). Note that the reference frequency of the system frequency is stored in arithmetic operation section  104 . 
     Subsequently, the control operation of arithmetic operation section  104  will be described. 
     Arithmetic operation section  104  obtains integral value Δf of a frequency deviation that is the deviation amount of the system frequency of power system  1  with respect to the reference frequency of the system frequency. Arithmetic operation section  104  controls the charge and discharge operation of power storage device  3  by using allotment coefficient K and integral value Δf of the frequency deviation, when an absolute value of integral value Δf of the frequency deviation is maximum value Δf max  of the integral values of the frequency deviations, or smaller. Meanwhile, when the absolute value of integral value Δf of the frequency deviation is larger than maximum value Δf max  of the integral values of the frequency deviations, arithmetic operation section  104  controls the charge and discharge operation of power storage device  3  by using allotment coefficient K and maximum value Δf max  of the integral values of the frequency deviations. 
     Next, storage battery SCADA  200  will be described. 
     Storage battery SCADA  200  is an example of a second control device or a battery control support device. Storage battery SCADA  200  has N of local charge and discharge devices  100  and N of power storage devices  3  under control. Storage battery SCADA  200  includes communicator  201 , database  202 , recognition section  203 , and arithmetic operation section  204 . 
     Communicator  201  is an example of second communication means. Communicator  201  communicates with respective local charge and discharge devices  100  and power supply instruction section  300 A. For example, communicator  201  receives the SOC and ID of power storage device  3  from each of local charge and discharge devices  100 . 
     Database  202  retains a storage battery distribution factor curve that is used to determine a chargeable and dischargeable capacity of power storage device  3  from the SOC of power storage device  3  received by communicator  201 . Furthermore, database  202  also retains rated output P(n) of each of power storage devices  3  that is used to determine the chargeable and dischargeable capacity. Note that as rated output P(n) of power storage device  3 , the rated output of an unillustrated power convertor (an AC/DC converter) that is connected to power storage device  3  is used. 
       FIGS. 3A and 3B  each show an example of the storage battery distribution factor curve.  FIG. 3A  shows an example of storage battery distribution factor curve  202   a  at the time of discharge, and  FIG. 3B  shows an example of storage battery distribution factor curve  202   b  at the time of charge. 
     Recognition section  203  is an example of recognition means. Recognition section  203  recognizes power amounts (hereinafter, called “allotted power amounts”) that are allotted to power storage devices  3  under control of storage battery SCADA  200  in order to adjust the power amount in power system  1 . The allotted power amount is an example of a situation of the power system. 
     Recognition section  203  derives total adjustable capacity P ES  showing the chargeable and dischargeable capacity of a storage battery group formed by N of power storage devices  3  from the SOC of N of power storage devices  3  by using the storage battery distribution factor curves in database  202 . Total adjustable capacity P ES  is an example of notification information. 
     Recognition section  203  transmits total adjustable capacity P ES  to power supply instruction section  300 A from communicator  201 , and thereafter, receives allotted power amount information showing the allotted power amount reflecting total adjustable capacity P ES  from power dispatching instruction section  300 A via communicator  201 . Recognition section  203  recognizes the allotted power amount in the allotted power amount information. 
     In the present exemplary embodiment, as the allotted power amount information, a charge and discharge gain line that shows the LFC (load frequency control) allotted capacity LFC ES  that shows the maximum allotted power amount, and maximum value Δf max  of the integral values of the frequency deviation are used. 
     Note that “the maximum value of the integral values of the frequency deviations” means “a maximum deflection amount of the integral value of the frequency deviation” that can be handled with the output amount of LFC ES , with respect to the total output LFC ES  of the number of storage batteries under control, and if the integral value becomes the maximum value or larger, handling with LFC ES  becomes difficult. 
       FIG. 4  is a diagram showing an example of the charge and discharge gain line. Details of the charge and discharge gain line will be described later. 
     Arithmetic operation section  204  is an example of processing means. Arithmetic operation section  204  generates allotment information (allotment coefficient K and maximum value Δf max  of the integral values of frequency deviations) based on the SOC of power storage device  3  received by communicator  201 , and the charge and discharge gain line recognized by recognition section  203 . Arithmetic operation section  204  transmits the allotment information (allotment coefficient K and maximum value Δf max  of the integral values of the frequency deviations) to respective local charge and discharge devices  100  from communicator  201 . 
     Next, power supply instruction section  300 A will be described. 
     Power supply instruction section  300 A is an example of an external control device. Power supply instruction section  300 A includes frequency meter  301 , communicator  302  and arithmetic operation section  303 . 
     Frequency meter  301  detects a system frequency of power system  1 . 
     Communicator  302  communicates with storage battery SCADA  200 . For example, communicator  302  receives total adjustable capacity P ES  from storage battery SCADA  200 . 
     Arithmetic operation section  303  controls the operation of power supply instruction section  300 A. 
     For example, arithmetic operation section  303  calculates area requirement (Area Requirement: AR) that is an output correction amount of a power station by using the system frequency detected by frequency meter  301 . Arithmetic operation section  303  derives the LFC capacity by using area requirement AR, the LFC adjustment capacity of thermal power generation equipment  4  that is to be a control target, and total adjustable capacity P ES  of the storage battery group that is to be a control target. Arithmetic operation section  303  acquires the LFC adjustment capacity of thermal power generation equipment  4  from a thermal power generation equipment control section not illustrated, and total adjustable capacity P ES  is supplied to arithmetic operation section  303  from communicator  302 . 
     Arithmetic operation section  303  assigns a capacity from which an abrupt variation component is excluded out of the LFC capacity to thermal power generation equipment  4 , and assigns remaining LFC capacity LFC ES  (note that LFC ES &lt;=P ES ) to the storage battery group. For example, arithmetic operation section  303  extracts the abrupt variation component (capacity LFC ES ) from the LFC capacity by using a high pass filter that passes only variation components with periods of 10 seconds or shorter among the LFC capacities. 
     Arithmetic operation section  303  deals capacity LFC E5  as LFC assignment capacity LFC ES , and generates a charge and discharge gain line (see  FIG. 4 ) that shows LFC assignment capacity LFC ES , and maximum value Δf max  of the integral values of the frequency deviations that are fixed in advance. 
     Arithmetic operation section  303  transmits the charge and discharge gain line to storage battery SCADA  200  from communicator  302 . 
     Next, outlines of operations will be described. 
     (1) Storage battery SCADA  200  accepts SOC of each of power storage devices  3  to be a control target from each of local charge and discharge devices  100  at periods T, and thereby collects SOC of each of power storage devices  3 . Period T is approximately one minute. 
     (2) Storage battery SCADA  200  derives total adjustable capacity P ES  based on the SOC of each of power storage devices  3  each time storage battery SCADA  200  collects SOC of each of power storage devices  3 . 
     (3) Subsequently, storage battery SCADA  200  transmits total adjustable capacity P ES  to power supply instruction section  300 A at periods T m . Period T m  is period T or more, and is four minutes, for example. 
     (4) Power dispatching instruction section  300 A calculates LFC allotment capacity LFC ES  (LFC ES &lt;=P ES ) with respect to a power storage device  3  group that is controlled by storage battery SCADA  200 , each time that power supply instruction section  300 A receives total adjustable capacity P ES . 
     (5) Power dispatching instruction section  300 A creates a charge and discharge gain line by using LFC assignment capacity LFC ES  and maximum value Δf max  of the integral values of the frequency deviations, each time that power supply instruction section  300 A calculates LFC assignment capacity LFC ES , and transmits the charge and discharge gain line to storage battery SCADA  200 . 
     (6) Storage battery SCADA  200  calculates allotment coefficient K in accordance with the newest charge and discharge gain line from power supply instruction section  300 A. 
     (7) Subsequently, storage battery SCADA  200  transmits allotment information (allotment coefficient K and maximum value Δf max  of the integral values of frequency deviations) to each of local charge and discharge devices  100  at periods T. 
     (8) Each of local charge and discharge devices  100  calculates a local charge and discharge gain line that defines the charge and discharge operation of power storage device  3 , based on allotment coefficient K and maximum value Δf max  of the integral values of the frequency deviations. The local charge and discharge gain line will be described later. 
     (9) Each of local charge and discharge devices  100  controls the charge and discharge operation of power storage device  3  by using the local charge and discharge gain line and the system frequency. 
     Next, details of the operations will be described. 
     First, an operation of storage battery SCADA  200  deriving total adjustable capacity P ES  based on SOC of power storage device  3  (hereinafter, called a “P ES  deriving operation”) will be described. Note that in order to derive total adjustable capacity P ES , information of rated output P(n) and the like of the storage battery of each ID (the kWh of the battery, the usable SOC range, for example, the range of 30% to 90% and the like) is needed. The information thereof is basically stationary information, and therefore, in the present exemplary embodiment, storage battery SCADA  200  is assumed to acquire the information thereof from each of local charge and discharge devices  100  in advance. 
       FIG. 5  is a sequence diagram for explaining the P ES  deriving operation. In  FIG. 5 , the number of local charge and discharge devices  100  is set at one to simplify explanation. 
     Communicator  201  of storage battery SCADA  200  transmits an information request that requests SOC from each of local charge and discharge devices  100  (step S 501 ). 
     In each of local charge and discharge devices  100 , arithmetic operation section  104  causes detector  101  to detect SOC of power storage device  3  when arithmetic operation section  104  receives the information request requesting SOC via communicator  102  (step S 502 ). 
     Subsequently, arithmetic operation section  104  transmits SOC detected by detector  101  together with ID, to storage battery SCADA  200  from communicator  102  (step S 503 ). 
     Hereinafter, explanation will be made with ID being assumed to be a consecutive number (n) from “1” to “N”. 
     When storage battery SCADA  200  receives SOC (hereinafter, called “SOC(n)”) that is assigned with ID from each of local charge and discharge devices  100 , storage battery SCADA  200  derives total adjustable capacity P ES  (step S 504 ). 
     Storage battery SCADA  200  and each of local charge and discharge devices  100  repeat the operation of steps S 501  to S 504 , namely, the P ES  deriving operation at periods T. 
     Next, a method for deriving total adjustable capacity P ES  will be described. 
     Communicator  201  of storage battery SCADA  200  collects real-time SOC(n) from each of local charge and discharge devices  100 . 
     Subsequently, recognition section  203  of storage battery SCADA  200  derives storage battery distribution factor α discharge (n) at the time of discharge and storage battery distribution factor α charge (n) at the time of charge, for each of power storage devices  3 , by using SOC(n) and storage battery distribution factor curves  202   a  and  202   b  (see  FIGS. 3A and 3B ) that are retained in database  202 . 
     Here, as the storage battery distribution factor curves shown in  FIGS. 3A and 3B , curves with an objective of basically keeping SOC at approximately 50% at the time of charge and at the time of discharge are used. Note that the storage battery distribution factor curves are properly changeable without being limited to the storage battery distribution factor curves shown in  FIGS. 3A and 3B . 
     Subsequently, recognition section  203  derives P ES,discharge  and P ES,charge  by using storage battery distribution factor α discharge (n) at the time of discharge, storage battery distribution factor α charge (n) at the time of charge, respective rated outputs P(n) of N of power storage devices  3  in total, and formulas shown in formula 1 and formula 2. 
     
       
         
           
             
               
                 
                   
                     P 
                     
                       ES 
                       , 
                       clscharge 
                     
                   
                   = 
                   
                     
                       ∑ 
                       
                         n 
                         = 
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                         ⁡ 
                         
                           ( 
                           n 
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                           ( 
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                       , 
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                           ( 
                           n 
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     Subsequently, recognition section  203  adopts a smaller value out of P ES,discharge  and P ES,charge , as total adjustable capacity P ES . This is because in order to adjust the system frequency, charge and discharge in power storage device  3  is required with about the same frequency, and the total adjustable capacity with which both charge and discharge can be performed is needed. Note that the total adjustable capacity is the value with which charge and discharge are considered to be able to be continued at least during the time period of period T. 
     Next, an operation of storage battery SCADA  200  communicating with power supply instruction section  300 A and recognizing a charge and discharge gain line (hereinafter, called a “recognition operation”) will be described. 
       FIG. 6  is a sequence diagram for explaining the recognition operation. 
     Arithmetic operation section  303  of power supply instruction section  300 A calculates area requirement AR by using the system frequency detected by frequency meter  301  (step S 601 ). 
     Subsequently, arithmetic operation section  303  collects the LFC adjustment capacity of thermal power generation equipment  4  from a thermal power generation equipment controller not illustrated (step S 602 ). 
     Meanwhile, communicator  201  of storage battery SCADA  200  transmits the newest total adjustable capacity P ES  among calculated total adjustable capacities P is  to power supply instruction section  300 A (step S 603 ). 
     Communicator  302  of power supply instruction section  300 A receives the newest total adjustable capacity P ES  transmitted from communicator  201  of storage battery SCADA  200 , and outputs the newest total adjustable capacity P ES  to arithmetic operation section  303 . 
     When arithmetic operation section  303  accepts the newest total adjustable capacity P ES , arithmetic operation section  303  derives an LFC capacity by using area requirement AR, the LFC adjustment capacity of thermal power generation equipment  4 , and the newest total adjustable capacity P ES  thereof. Subsequently, arithmetic operation section  303  assigns a capacity with an abrupt variation component excluded from the LFC capacity to thermal power generation equipment  4 , and assigns the remaining LFC capacity LFC ES  (note that LFC ES &lt;=P ES ) to the storage battery group as LFC assignment capacity LFC ES  (step S 604 ). 
     In the present exemplary embodiment, arithmetic operation section  303  determines a ratio of assignment of the LFC capacity to thermal power generation equipment  4  and assignment of the LFC capacity to the storage battery group (LFC assignment capacity LFC ES ), with an eye to economy while considering assignment amounts of EDC (Economic power supply control) component. 
     Subsequently, arithmetic operation section  303  generates a charge and discharge gain line (see  FIG. 4 ) showing LFC assignment capacity LFC ES , and maximum value Δf max  of the integral values of the frequency deviations set in advance (step S 605 ). 
     The charge and discharge gain line shown in  FIG. 4  shows the charge and discharge amount of the storage battery group with respect to integral value Δf of the frequency deviation. The charge and discharge gain line changes to be line  400 A and line  400 B in accordance with the value (LFC ES  and LFC ES ′) of LFC assignment capacity LFC ES  within the range of “LFC assignment capacity LFC ES &lt;=total adjustable capacity P ES ”. Note that as the charge and discharge gain line, a charge and discharge gain line with use of a frequency deviation may be used, other than the charge and discharge gain line shown in  FIG. 4 . In this case, the operation becomes a governor free operation, rather than an LFC operation. 
     Subsequently, arithmetic operation section  303  transmits the charge and discharge gain line to storage battery SCADA  200  from communicator  302  (step S 606 ). 
     Storage battery SCADA  200  and power supply instruction section  300 A repeat the operation of steps S 601  to S 606 , that is, the recognition operation at periods T m  (for example, T m =four minutes). 
     Note that recognition section  203  of storage battery SCADA  200  receives charge and discharge gain lines via communicator  201 , and retains only the newest charge and discharge gain line among the charge and discharge gain lines. 
     Next, an operation of storage battery SCADA  200  generating allotment information and transmitting the allotment information to each of local charge and discharge devices  100 , and each of local charge and discharge devices  100  that derive the local charge and discharge gain line for controlling charge and discharge of power storage device  3  based on the allotment information (hereinafter, called an “allotment operation”) will be described. 
       FIG. 7  is a sequence diagram for describing the allotment operation. In  FIG. 7 , the number of local charge and discharge devices  100  is set at one in order to simplify explanation. 
     Arithmetic operation section  204  of storage battery SCADA derives allotment coefficient K by using LFC assignment capacity LFC ES  shown in the newest charge and discharge gain line retained by recognition section  203 , the newest total adjustable capacity P ES  which recognition section  203  has, and mathematical expression shown in formula 3 (step S 701 ). 
     
       
         
           
             
               
                 
                   K 
                   = 
                   
                     
                       LFC 
                       ES 
                     
                     
                       P 
                       ES 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Formula 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     3 
                   
                   ] 
                 
               
             
           
         
       
     
     Subsequently, arithmetic operation section  204  transmits allotment information showing allotment coefficient K and maximum value Δf max  of the integral values of the frequency deviations shown in the newest charge and discharge gain line to each of local charge and discharge devices  100  from communicator  201  (step S 702 ). Note that formula 3 is used as allotment coefficient K in the present exemplary embodiment, but besides the above, a flexible operation can be performed such as an operation of instructing the individual storage batteries to forcibly issue outputs that is close to a limit as the value of allotment coefficient K or the like at the time of a desperate situation. 
     Note that in the present exemplary embodiment, the following processing is executed in step S 702 . 
     Arithmetic operation section  204  determines a smaller value out of the newest storage battery distribution factor α discharge (n) at the time of discharge and storage battery distribution factor α charge (n) at the time of charge that are derived by recognition section  203  as storage battery distribution factor α (n), for each of power storage devices  3 . 
     Subsequently, arithmetic operation section  204  generates operation-related information showing storage battery distribution factor α(n) and rated output P(n) that is retained in database  202 , for each of power storage devices  3 . 
     Subsequently, arithmetic operation section  204  adds allotment information to each operation-related information, and transmits the allotment information to which the operation-related information is added from communicator  201  to local charge and discharge device  100  corresponding to power storage device  3  corresponding to the operation-related information. 
     In each of local charge and discharge devices  100 , arithmetic operation section  104  receives the allotment information with the operation-related information via communicator  102 . 
     Arithmetic operation section  104  derives local charge and discharge gain coefficient G(n) by using the allotment information with the operation-related information and the mathematical expression shown in formula 4 (step S 703 ). 
     
       
         
           
             
               
                 
                   
                     G 
                     ⁡ 
                     
                       ( 
                       n 
                       ) 
                     
                   
                   = 
                   
                     
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                       · 
                       
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                           ( 
                           n 
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                       Δ 
                       ⁢ 
                       
                           
                       
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                         f 
                         max 
                       
                     
                   
                 
               
               
                 
                   [ 
                   
                     Formula 
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                     4 
                   
                   ] 
                 
               
             
           
         
       
     
     Note that the values in the mathematical expression of formula 4 are shown in the allotment information with the operation-related information. 
     Subsequently, arithmetic operation section  104  derives local charge and discharge gain line  800 A shown in  FIG. 8  by using local charge and discharge gain coefficient G(n), and maximum value Δf max  of the integral values of the frequency deviations shown in the allotment information with the operation-related information (step S 704 ). 
     Local charge and discharge gain line  800 A shown in  FIG. 8  becomes a straight line that passes through origin 0, and has a gradient that is local charge and discharge gain coefficient G(n) when integral value Δf of the frequency deviation is in a range of −Δf max ≤Δf=Δf max , takes a constant value of “−K·α(n)·P(n)” (the minus sign represents discharge) when integral value Δf of the frequency deviation is in a range of Δf&lt;−Δf max , and takes a constant value of “K·α(n)·P(n)” when integral value Δf of the frequency deviation is in a range of Δf max &lt;Δf. 
     Storage battery SCADA  200  and each local charge and discharge device  100  repeat steps S 701  to S 704  at periods T (for example, T=one minute). 
     In each of local charge and discharge devices  100 , arithmetic operation section  104  receives pieces of allotment information together with the operation-related information via communicator  102 , and retains only the newest piece of allotment information with the operation-related information from among the pieces of allotment information together with the operation-related information. 
     Next, the operation of local charge and discharge device  100  controlling charge and discharge of power storage device  3  based on the allotment information with the operation-related information and the system frequency (hereinafter, called a “charge and discharge control operation”) will be described. 
       FIG. 9  is a sequence diagram for describing the charge and discharge control operation. 
     In local charge and discharge device  100 , arithmetic operation section  104  causes frequency meter  103  to detect a system frequency (step S 901 ). 
     Subsequently, arithmetic operation section  104  calculates integral value Δf of the frequency deviation by subtracting the reference frequency of the system frequency from the detection result of frequency meter  103  and integrating the subtracted result (step S 902 ). Note that arithmetic operation section  104  may use a system frequency of power system  1  that is received from outside, instead of the system frequency of power system  1  that is detected by frequency meter  103 . In this case, arithmetic operation section  104  also functions as second detection means. 
     Subsequently, arithmetic operation section  104  calculates a charge amount or a discharge amount of power storage device  3  in accordance with integral value Δf of the frequency deviation and the local charge and discharge gain line (step S 903 ). 
     In the present exemplary embodiment, when the absolute value of integral value Δf of the frequency deviation is maximum value Δf max  of the integral values of the frequency deviations or smaller in step S 903 , arithmetic operation section  104  calculates the absolute value of a value (G(n)·Δf) that is obtained by multiplying local charge and discharge gain coefficient G(n) by integral value Δf of the frequency deviation. Meanwhile, when the absolute value of integral value Δf of the frequency deviation is larger than maximum value Δf max  of the integral values of the frequency deviations, arithmetic operation section  104  calculates a value (K·α(n)·P(n)) obtained by multiplying allotment coefficient K, storage battery distribution factor α(n) and rated output P(n) by one another. In this example, the case where the gradients of G(n) are the same on the charge side and the discharge side, namely, symmetrical with respect to a point is shown in  FIG. 8 , but in reality, the case where the gradients are not symmetrical with respect to a point is assumed, and in that case, G(n) is determined in a similar way. 
     Subsequently, when integral value Δf of the frequency deviation is a positive value, arithmetic operation section  104  causes power storage device  3  to execute a charge operation by a power amount shown in the calculation result, and causes power storage device  3  to execute a discharge operation by a power amount shown in the calculation result, when integral value Δf of the frequency deviation is a negative value (step S 904 ). 
     Each local charge and discharge device  100  repeats steps S 901  to S 904  at periods T l  (for example, T l =0.1 seconds). As a result, the value of the integral value of the frequency deviation changes at each time, and charge and discharge based on G(n)·Δf are performed at each time. 
     When N=1000 of power storage devices were controlled in power control system  1000  that is described above, communication problems occurred for 20 seconds between load dispatching instruction section  300 A and storage battery SCADA halfway, but since the problem occurred during the interval of four minutes in which the charge and discharge gain line was transmitted, the control state did not change before and after the communication problem, and therefore, it was possible to stably control limiting system frequency variation. 
     Furthermore, from the viewpoint of total optimization of the thermal power generation equipment on the system side and the power storage devices, control allotment from the standpoint of the economical use and the response speed of the thermal power generation equipment is enabled to be given to the distributed storage battery group. 
     Next, the effect of the present exemplary embodiment will be described. 
     In the present exemplary embodiment, the time interval at which local charge and discharge device  100  acquires allotment information from storage battery SCADA  200  is longer than the operation interval at which local charge and discharge device  100  controls the operation of power storage device  3  by using the allotment information. Therefore, as compared with the case where the time interval, at which local charge and discharge device  100  acquires the allotment information, is the operation interval of power storage device  3  or shorter, the processing of acquiring the allotment information is less influenced by communication problems that are likely to occur between local charge and discharge device  100  and storage battery SCADA  200 . 
     Note that the above-described effect is also brought about with local charge and discharge device  100  including detector  101 , communicator  102  and arithmetic operation section  104 . Furthermore, the above-described effect is also brought about with storage battery SCADA  200  including communicator  201 , recognition section  203  and arithmetic operation section  204 . Furthermore, the above-described effect is also brought about with the battery control system including local charge and discharge device  100  including detector  101 , communicator  102  and arithmetic operation section  104 , and storage battery SCADA  200  including communicator  201 , recognition section  203  and arithmetic operation section  204 . 
       FIG. 10  is a diagram showing the local charge and discharge device including detector  101 , communicator  102  and arithmetic operation section  104 . 
       FIG. 11  is a diagram showing storage battery SCADA  200  including communicator  201 , recognition section  203  and arithmetic operation section  204 . 
     Furthermore, frequency meter  103  measures the system frequency at an interval shorter than the time interval at which frequency meter  103  acquires the allotment information. Arithmetic operation section  104  controls the operation of power storage device  3  based on the newest system frequency measured by frequency meter  103 . Therefore, the operation of power storage device  3  can be adjusted in response to a change in the actual state of the power system, which is detected at a interval shorter than the time interval at which the allotment information is acquired. 
     Furthermore, communicator  102  executes the transmission and reception processing to transmit the detection result of detector  101  to storage battery SCADA  200  and to receive the allotment information from storage battery SCADA  200  at a predetermined time interval. Therefore, communicator  102  can receive the allotment information, as a response to transmission of the detection result of detector  101 . 
     Furthermore, storage battery SCADA  200  accepts the charge and discharge gain line that is used to generate allotment information from power supply instruction section  300 A that controls power system  1 . Therefore, it is possible to acquire the charge and discharge gain line with consideration given to the operation of thermal power generation equipment  4  on the system side, for example. Therefore, power demand and supply balance control by the thermal power generation equipment  4  on the system side and power storage device  3  can be carried out with high precision. 
     Furthermore, storage battery SCADA  200  accepts the charge and discharge gain line in which total adjustable capacity P ES  is reflected from power supply instruction section  300 A. Therefore, the load of power storage device  3  can be adjusted in accordance with the total adjustable capacity of power storage device  3 . 
     Furthermore, local charge and discharge device  100  controls the operation of power storage device  3  based on integral value Δf of the frequency deviation and the allotment information (the allotment coefficient K and maximum value Δf max  of the integral values of the frequency deviations). Therefore, the operation of power storage device  3  can be adjusted in response to not only the allotment information but also the actual change of the system frequency. 
     Note that in the present exemplary embodiment, when control of effective power P and reactive power Q in power storage device  3  is considered, the maximum value of the output amount of power storage device  3  that is assigned to control of reactive power P (in short, when the output of Q is separately used in parallel, the effect of the output maximum value becomes lower than the rated output of the output amount by P is taken into consideration) may be used instead of rated output P(n). 
     Furthermore, in the above-described exemplary embodiment, storage battery SCADA  200 , local control device  100  and the like properly collect and distribute time synchronization information in the process of information communication, and time synchronization is performed among the devices. 
     Furthermore, local charge and discharge device  100  may be realized by a computer. In this case, the computer reads and executes the program recorded in a recording medium such as computer-readable CD-ROM (Compact Disk Read Only Memory), and executes the respective functions that local charge and discharge device  100  has. The recording medium is not limited to a CD-ROM and other recording media can be used. 
     Furthermore, storage battery SCADA  200  may be realized by a computer. In this case, the computer reads and executes the program recorded in a computer-readable recording medium, and executes each of the functions that storage battery SCADA  200  has. 
     Furthermore, instead of power supply instruction section  300 A, a small-scale EMS (Energy Management System) that is installed in the vicinity of a distribution substation may be used. 
     Second Exemplary Embodiment 
       FIG. 12  is a diagram showing power control system  1000 A that adopts a battery control system of a second exemplary embodiment of the present invention. In  FIG. 12 , the components that have the same configurations as shown in  FIG. 1 or 2  are assigned the same reference signs. 
     In  FIG. 12 , power control system  1000 A includes power system  1 A, photovoltaic power generator (solar battery)  2 , power storage devices (storage batteries)  3 ( 1 ) to  3 ( n ), load  7 , local charge and discharge devices  100 A( 1 ) to  100 A(n), ESMS (Energy Storage Management System)  200 A, sensor-incorporating switch slave station  700 A, SVR slave station  700 B, and LRT (Load Ratio Transformer) slave station  700 C. 
     Local charge and discharge devices  100 A( 1 ) to  100 A(n) are in one-to-one correspondence with power storage devices (storage batteries)  3 ( 1 ) to  3 ( n ). Note that  FIG. 12  shows local charge and discharge device  100 A(i) from among local charge and discharge devices  100 A( 1 ) to  100 A(n) in order to simplify the explanation. 
     Each of local charge and discharge devices  100 A, ESMS  200 A, sensor-incorporating switch slave station  700 A, SVR slave station  700 B and LRT slave station  700 C are connected to communication network  800 . 
     Power system  1 A includes distribution substation LRT  1 A 1 , breakers  1 A 2 , switch  1 A 3 , sensor-incorporating switch  1 A 4 , SVR  1 A 5  and pole transformer  1 A 6 . 
     Power control system  1000 A limits variation in system frequency that result from changes in the amount of power generated by photovoltaic power generator  2 , due to weather conditions, which is of concern to power system  1 A, to which photovoltaic power generator  2  is interconnected, by a voltage adjusting operation of SVR  1 A 5  and charge and discharge operations of respective power storage devices  3 . 
     Power system  1 A is a system for supplying power to load  7  on the customer side. While power system  1 A also includes other devices (for example, thermal power generation equipment), these devices are omitted to simplify the explanation. 
     LRT  1 A 1 , SVR  1 A 5  and pole transformer  1 A 6  are voltage adjustors. Breaker  1 A 2 , switch  1 A 3  and sensor-incorporating switch  1 A 4  are used to disconnect a specific part of power system  1 A (for example, a part where a trouble occurs) from power system  1 A. 
     Each local charge and discharge device  100 A is an example of a first control device or a battery control device. Each local charge and discharge device  100 A also bears the function of a slave station provided in corresponding power storage device  3 . Note that the number of local charge and discharge devices  100 A and the number of power storage devices  3  are each one or more. 
       FIG. 13  is a diagram showing an example of local charge and discharge device  100 A(i). 
     In  FIG. 13 , local charge and discharge device  100 A(i) includes voltage detector  101 A 1 , empty capacity detector  101 A 2 , communicator  101 A 3 , and arithmetic operation section  101 A 4 . 
     Voltage detector  101 A 1  is an example of first detection means and second detection means. Voltage detector  101 A 1  detects voltage V i  of interconnection point i of power system  1 A and power storage device  3 ( i ) at periods T g  (for example, T g =10 minutes). Furthermore, voltage detector  101 A 1  detects voltage V i  of interconnection point i at periods T h  (for example, T h =0.1 seconds). Voltage V i  of interconnection point i is an example of a state of interconnection point i, battery-related information and a state of power system  1 A. Note that the state of the interconnection point is not limited to the voltage of the interconnection point and that other values may be used. 
     Empty capacity detector  101 A 2  detects empty capacity Q i  of power storage device  3 ( i ) at periods T g . Note that empty capacity Q i  of power storage device  3 ( i ) refers to capacity that can be used by power storage device  3 ( i ) to adjust the voltage of power system  1 A at the point of time, is calculated based on SOC, for example, and is ensured for the time period T g . 
     Communicator  101 A 3  is an example of first communication means. Communicator  101 A 3  communicates with ESMS  200 A. 
     Arithmetic operation section  101 A 4  executes a control information acquiring operation of obtaining operation control information to control the operation of power storage device  3 ( i ) from ESMS  200 A (transmission and reception processing), and a charge and discharge control operation to control a charge and discharge operation of power storage device  3 ( i ) based on the operation control information and voltage V i  at interconnection point i (battery operation control processing). 
     Arithmetic operation section  101 A 4  intermittently executes the control information acquiring operation, and executes the charge and discharge control operation at time intervals shorter than the time intervals of the control information acquiring operation. 
     Arithmetic operation section  101 A 4  repeatedly executes the control information acquiring operation at periods T g , and repeatedly executes the charge and discharge control operation at periods T h  (for example, T h =0.1 seconds). 
     Note that period T g  and Period T h  are not limited to 10 minutes and 0.1 seconds, and period T g  can be longer than period T h . 
     Furthermore, both or any one of the operation time intervals of the control information acquiring operation and the operation time interval of the charge and discharge control operation do not or does not have to be constant, and the shortest time interval from among the respective operation time intervals of the control information acquiring operation can be longer than the longest time from among the respective operation time intervals of the charge and discharge control operation. 
     Furthermore, arithmetic operation section  101 A 4  may execute the control information acquiring operation in response to the voltage request that requests voltage V i  of interconnection point i sent from ESMS  200 A, or may execute the control information acquiring operation autonomously. 
     Here, the control information acquiring operation of arithmetic operation section  101 A 4  will be described. 
     Arithmetic operation section  101 A 4  transmits voltage V i  of interconnection point i detected by voltage detector  101 A 1 , and empty capacity Q i  of power storage device  3 ( i ) detected by empty capacity detector  101 A 2  to ESMS  200 A from communicator  101 A 3 . 
     Communicator  101 A 3  transmits voltage V i  of interconnection point i and empty capacity Q i  of power storage device  3 ( i ) to ESMS  200 A, and thereafter, receives operation control information from ESMS  200 A. 
     Subsequently, the charge and discharge control operation of arithmetic operation section  101 A 4  will be described. Arithmetic operation section  101 A 4  controls the charge and discharge operation of power storage device  3 ( i ) based on the operation control information received by communicator  101 A 3 , and voltage V i  of interconnection point i detected by voltage detector  101 A 1 . 
     Next, sensor-incorporating switch slave station  700 A will be described. 
       FIG. 14  is a diagram showing an example of sensor-incorporating switch slave station  700 A. 
     Sensor-incorporating switch slave station  700 A is an example of an external control device. Sensor-incorporating switch slave station  700 A includes voltage detector  700 A 1 , communicator  700 A 2  and arithmetic operation section  700 A 3 . 
     Voltage detector  700 A 1  detects adjustment target voltage V T  that is a voltage of voltage adjustment target spot T (see  FIG. 17 ) in power system  1 A. 
     Communicator  700 A 2  communicates with ESMS  200 A. 
     Arithmetic operation section  700 A 3  transmits adjustment target voltage V T  detected by voltage detector  700 A 1  to ESMS  200 A from communicator  700 A 2  at periods T g . 
     Next, SVR slave station  700 B will be described. 
     SVR slave station  700 B communicates with ESMS  200 A. For example, SVR slave station  700 B notifies ESMS  200 A of an output voltage of SVR  1 A 5  at periods T g , and further, receives an SVR settling constant from ESMS  200 A at periods T g . 
     The SVR settling constant is information for determining the output range of the output voltage of SVR  1 A 5  (hereinafter, called the “conversion output range”) at the time of adjustment-target voltage V T  falling within a proper voltage range. In the present exemplary embodiment, as the SVR settling constant, center value Vref(t) of the conversion output range, upper limit value Vref_high(t) of the conversion output range, and lower limit value Vref_low(t) of the conversion output range are used. Note that Vref(t) that expresses the center value of the conversion output range may be omitted. 
     SVR slave station  700 B sets the newest SVR settling constant to SVR  1 A 5 . Note that SVR  1 A 5  is an example of the voltage adjustment device. SVR  1 A 5  switches a tap (not illustrated) of SVR  1 A 5  and changes adjustment target voltage V T  to be within a proper voltage range, when adjustment target voltage V T  is continuously outside the proper voltage range for settling time period Ts, namely, when the output voltage of SVR  1 A 5  is continuously outside the conversion output range for the settling time period Ts. Note that the control method of SVR  1 A 5  described above is a known technique. Furthermore, settling time period Ts is an example of a specific time period. 
     Next, ESMS  200 A will be described. 
       FIG. 15  is a diagram showing an example of ESMS  200 A. 
     ESMS  200 A is an example of a second control device or a battery control support device. ESMS  200 A includes communicator  200 A 1 , recognition section  200 A 2  and arithmetic operation section  200 A 3 . 
     Communicator  200 A 1  is an example of second communication means. Communicator  200 A 1  communicates with respective local charge and discharge devices  100 A and sensor-incorporating switch slave station  700 A. For example, communicator  200 A 1  receives voltages V of respective interconnection points and empty capacities Q of corresponding power storage devices  3  from respective local charge and discharge devices  100 A. Furthermore, communicator  200 A 1  receives adjustment target voltage V T  from sensor-incorporating switch slave station  700 A. 
     Recognition section  200 A 2  is an example of recognition means. Recognition section  200 A 2  recognizes (stores) the information (voltages V of the respective interconnection points, empty capacities Q of respective power storage devices  3  and adjustment target voltage V T ) received by communicator  200 A 1  by associating the information with reception time points. Note that adjustment target voltage V T  is an example of the situation of power system  1 A. 
     Arithmetic operation section  200 A 3  is an example of processing means. Arithmetic operation section  200 A 3  generates correlation information showing the correlation of voltage V of the interconnection point and adjustment target voltage V T  for each of the interconnection points based on voltage V of each of the interconnection points received by communicator  200 A 1 , and adjustment target voltage V T  recognized by recognition section  200 A 2 . 
     Furthermore, arithmetic operation section  200 A 3  derives voltage adjustment allotment information a based on the newest empty capacity Q of each of power storage devices  3 . For example, when arithmetic operation section  200 A 3  is notified of respective empty capacities Q of a plurality of power storage devices  3 , arithmetic operation section  200 A 3  derives voltage adjustment allotment information a that makes the ratio of allotments higher for larger empty capacities Q among the empty capacities Q whose arithmetic operation section  200 A 3  is notified, for each of power storage devices  3 . 
     Arithmetic operation section  200 A 3  generates the operation control information including the correlation information and voltage adjustment allotment information α, for each of power storage devices  3 , and transmits each piece of the operation control information to local charge and discharge device  100 A corresponding to power storage device  3  that corresponds to the operation control information, from communicator  200 A 1 . 
     Furthermore, arithmetic operation section  200 A 3  generates SVR settling constants (Vref(t), Vref_high(t) and Vref_low(t)) based on adjustment target voltage V T , and the output voltage of SVR  1 A 5  whose arithmetic operation section  200 A 3  is notified from SVR slave station  700 B. Note that a method for generating the SVR settling constants is a known technique, and therefore, a detailed explanation will be dropped. Arithmetic operation section  200 A 3  transmits the SVR settling constants (Vref(t), Vref_high(t) and Vref_low(t)) to SVR slave station  700 B from communicator  200 A 1 . 
     Next, operations will be described. 
     First, an operation of generating the SVR settling constants and setting the SVR settling constants to SVR  1 A 5  (hereinafter, called a “setting operation”) will be described. 
       FIG. 16  is a sequence diagram for describing the setting operation. 
     In sensor-incorporating switch slave station  700 A, arithmetic operation section  700 A 3  causes voltage detector  700 A 1  to detect adjustment target voltage V T  (step S 1601 ), and transmits adjustment target voltage V T  detected by voltage detector  700 A 1  to ESMS  200 A from communicator  700 A 2  (step S 1602 ). 
     Furthermore, SVR slave station  700 B detects the output voltage of SVR  1 A 5 , and transmits the output voltage of SVR  1 A 5  to ESMS  200 A (step S 1603 ). 
     In ESMS  200 A, when communicator  200 A 1  receives adjustment target voltage V T  from sensor-incorporating switch slave station  700 A and the output voltage of SVR  1 A 5  from SVR slave station  700 B, recognition section  200 A 2  stores adjustment target voltage V T  received by communicator  200 A 1  and the output voltage of SVR  1 A 5  by associating adjustment target voltage V T  and the output voltage with each other. 
     Subsequently, arithmetic operation section  200 A 3  derives the SVR settling constants (Vref(t), Vref_high(t) and Vref_low(t)) based on adjustment target voltage V T  and the output voltage of SVR  1 A 5  in recognition section  200 A 2  (step S 1604 ). 
     Subsequently, arithmetic operation section  200 A 3  transmits the SVR settling constants to SVR slave station  700 B from communicator  200 A 1  (step S 1605 ). 
     When SVR slave station  700 B receives SVR settling constants, SVR slave station  700 B sets the SVR settling constants to SVR  1 A 5  (step S 1606 ). Note that when SVR settling constants are already set to SVR  1 A 5 , SVR slave station  700 B updates the SVR settling constants set to SVR  1 A 5  to the newest SVR settling constants. 
     Sensor-incorporating switch slave station  700 A, SVR slave station  700 B and ESMS  200 A repeat steps S 1601  to S 1606  at periods T g . 
     Next, the operation of SVR  1 A 5  will be described. 
     When the output voltage of SVR  1 A 5  is outside upper limit value Vref_high(t) of the conversion output range specified by the SVR settling constants continuously for settling time period Ts, SVR  1 A 5  switches the tap of SVR  1 A 5  to lower the output voltage of SVR  1 A 5 , and changes the output voltage of SVR  1 A 5  to a voltage within the conversion output range. 
     Furthermore, when the output voltage of SVR  1 A 5  is continuously outside lower limit value Vref_low(t) of the conversion output range specified by the SVR settling constants for the settling time period Ts, SVR  1 A 5  switches the tap of SVR  1 A 5  to raise the output voltage of SVR  1 A 5 , and changes the output voltage of SVR  1 A 5  to a voltage within the conversion output range. 
     Note that settling time period Ts may be the value set in advance or may be changed with the lapse of time with consideration given to extending the life of SVR  1 A 5  and a secular change of SVR  1 A 5 . 
     Though the voltage of power system  1 A is adjusted by the operation of SVR  1 A 5 , high-speed variation components from among the variation components of the system voltage, for example, the components that result from output of a renewable power supply the power generation amount of which changes irregularly in accordance with the weather, cannot be handled with only the voltage adjustment by SVR  1 A 5 . 
     Therefore, in the present exemplary embodiment, the voltage variation components that cannot be handled with the voltage adjustment by SVR  1 A 5  are reduced by the charge and discharge operations of respective power storage devices  3 . 
     Next, an operation of ESMS  200 A that generates operation control information that is required to perform the charge and discharge operations of power storage devices  3 , and that transmits the operation control information to respective local charge and discharge devices  100 A (hereinafter, called a “generation operation”) will be described. 
       FIG. 17  is a sequence diagram for describing the generation operation. 
     In sensor-incorporating switch slave station  700 A, arithmetic operation section  700 A 3  causes voltage detector  700 A 1  to detect adjustment target voltage V T  (step S 1701 ), and transmits adjustment target voltage V T  detected by voltage detector  700 A 1  to ESMS  200 A from communicator  700 A 2  (step S 1702 ). 
     In ESMS  200 A, each time communicator  200 A 1  receives adjustment target voltage V T  from sensor-incorporating switch slave station  700 A, recognition section  200 A 2  stores adjustment target voltage V T  received by communicator  200 A 1 . 
     Subsequently, arithmetic operation section  200 A 3  of ESMS  200 A calculates average value V T,AVE  of adjustment target voltage V T  in recognition section  200 A 2  (step S 1703 ). Recognition section  200 A 2  retains average value V T,AVE  that is the calculation result. 
     Meanwhile, in each of local charge and discharge devices  100 A, arithmetic operation section  101 A 4  causes voltage detector  101 A 1  to detect voltage V of the interconnection point, and retains voltage V (step S 1704 ). Hereinafter, voltage V i  of interconnection point i will be cited as an example and described in order to simplify the explanation. 
     Subsequently, arithmetic operation section  101 A 4  calculates average value V i,AVE  of retained voltages V i (step S 1705 ). 
     Subsequently, arithmetic operation section  101 A 4  transmits average value V i,AVE  to ESMS  200 A from communicator  101 A 3  (step S 1706 ). 
     In ESMS  200 A, each time communicator  200 A 1  receives an average value (hereinafter, “average value V i,AVE ” will be described) from each of local charge and discharge devices  100 A, recognition section  200 A 2  stores average value V i,AVE  received by communicator  200 A 1 . 
     Subsequently, arithmetic operation section  200 A 3  of ESMS  200 A derives a correlation function at a time point t of average value V i,AVE  and average value V T,AVE  in recognition section  200 A 2  as follows by using a mechanical learning method or the like, for example, for each interconnection point (step S 1707 ).
 
Correlation function: V   T,AVE ( t )= a   i ( t )· V   i,AVE ( t )+ b   i ( t )
 
     In the present exemplary embodiment, arithmetic operation section  200 A 3  derives a correlation function by using a plurality of average values V i,AVE  ( 10  average values V i,AVE  in sequence from the newest one, for example) in the interconnection point, and a plurality of average value V T,AVE  ( 10  average values V T,AVE  in sequence from the newest one, for example), for each of the interconnection points. 
     Furthermore, in each of local charge and discharge devices  100 A, arithmetic operation section  101 A 4  causes empty capacity detector  101 A 2  to detect empty capacity Q(t) of power storage device  3  (step S 1708 ), and transmits empty capacity Q(t) of power storage device  3 , which is detected by empty capacity detector  101 A 2  (for example, empty capacity Q i (t) of power storage device  3 ( i )) to ESMS  200 A from communicator  101 A 3  (step S 1709 ). 
     Subsequently, arithmetic operation section  200 A 3  of ESMS  200 A derives voltage adjustment allotment information α(t) of each of power storage devices  3  (for example, voltage adjustment allotment information a i (t) of power storage device  3 ( i )) based on the latest empty capacity Q(t) of each of power storage devices  3  (step S 1710 ). 
     Subsequently, arithmetic operation section  200 A 3  generates operation control information including coefficients a i (t) and b i (t) of the correlation function and voltage adjustment allotment α i (t) for each of power storage devices  3 , and transmits the operation control information to local charge and discharge device  100 A corresponding to power storage device  3  that corresponds to the operation control information, from communicator  200 A 1  (step S 1511 ). Note that coefficients a i (t) and b i (t) of the correlation function are examples of correlation information. 
     In local charge and discharge device  100 A, when arithmetic operation section  101 A 4  receives the operation control information (coefficients a i (t) and b i (t) of the correlation function and voltage adjustment allotment α i (t)) via communicator  101 A 3 , arithmetic operation section  101 A 4  retains the operation control information. Note that when arithmetic operation section  101 A 4  already retains the operation control information, arithmetic operation section  101 A 4  updates the operation control information already retained to the latest operation control information. 
     Sensor-incorporating switch slave station  700 A, local charge and discharge device  100 A and ESMS  200 A repeat steps S 1501  to S 1511  at periods T g . 
     Note that as adjustment target voltage V T  that is used in calculation of the average values in step S 1703 , adjustment target voltage V T  provided in step S 1602  of  FIG. 16  may be used. In this case, steps S 1701  and S 1702  can be omitted. 
     Next, the operation of each of local charge and discharge devices  100 A that control reactive power output Q of power storage device  3  based on the operation control information and the voltage of the interconnection point (hereinafter, called a “power control operation”) will be described. The power control operations in respective local charge and discharge devices  100 A are common, and therefore, for simplification of explanation, the power control operation in local charge and discharge device  100 A(i) will be described hereinafter. 
       FIG. 18  is a sequence diagram for describing the power control operation. 
     Arithmetic operation section  101 A 4  causes voltage detector  101 A 1  to detect voltage V i  of interconnection point i (step S 1801 ). 
     Subsequently, arithmetic operation section  101 A 4  calculates adjustment target voltage V T  from voltage V i  of interconnection point i, by performing the following calculation and using coefficients a i (t) and b i (t) of the correlation function included in the operation control information (step S 1802 ).
 
Adjustment target voltage  V   T ( t )= a   i ( t )· V   i ( t )+ b   i ( t )
 
     Subsequently, arithmetic operation section  101 A 4  determines the magnitude relation of the calculated adjustment target voltage V T , and upper limit threshold value V mu  and lower limit threshold V ml  that are set in arithmetic operation section  101 A 4  in advance. Note that upper limit threshold value V mu  is a value larger than the upper limit value of the voltage range without requiring switching with respect to adjustment target voltage V T , and lower limit threshold value V ml  is a value smaller than the lower limit value of the voltage range without requiring switching with respect to adjustment target voltage V T . 
     When calculated adjustment target voltage V T  is larger than upper limit threshold value V mu , arithmetic operation section  101 A 4  calculates reactive power amount Q i (t) in accordance with mathematical expression of 
     Q i (t)=[V T (t)−V mu ]×α i (t)/(dV i (t)/dQ i (t)). Subsequently, arithmetic operation section  101 A 4  causes power storage device  3 ( i ) to output calculated reactive power amount Q i (t) (step S 1804 ). 
     Furthermore, when calculated adjustment target voltage V T  is smaller than lower limit threshold value V ml , arithmetic operation section  101 A 4  calculates reactive power amount Q i (t) in accordance with mathematical expression of 
     Q i (t)=[V T (t)−Vml]×α i (t)/(dV i (t)/dQ i (t)). Subsequently, arithmetic operation section  101 A 4  causes power storage device  3 ( i ) to output calculated reactive power amount Q i (t) (step S 1804 ). 
     Note that when calculated adjustment target voltage V T  is from a lower limit threshold value V ml  to upper limit threshold value V mu  inclusive, arithmetic operation section  101 A 4  determines that adjustment is not necessary, and does not control charge and discharge of power storage device  3 ( i ). 
     Local charge and discharge device  100  repeats steps S 1801  to S 1803  at periods T l . 
     Next, the effect of the present exemplary embodiment will be described. 
     According to the present exemplary embodiment, in local charge and discharge device  100 A, arithmetic operation section  101 A 4  controls the operation of power storage device  3  based on operation control information provided from ESMS  200 A, and the voltage of the interconnection point measured by voltage detector  101 A 1 . Therefore, it becomes possible to adjust the operation of power storage device  3  in response to an actual change in the state of the power system while following the operation control information. 
     Furthermore, ESMS  200 A generates the correlation information showing the correlation of the voltage of the interconnection point detected by local charge and discharge device  100 A and the adjustment target voltage. Local charge and discharge device  100 A calculates the adjustment target voltage from the voltage of the interconnection point detected by local charge and discharge device  100 A by using the correlation information, and when the calculated result is outside the voltage range (the predetermined voltage range) defined by upper limit threshold value V mu  and lower limit threshold value V ml , local charge and discharge device  100 A controls the operation of power storage device  3  by using the correlation information so that the adjustment target voltage is within the voltage range. 
     Therefore, the adjustment target voltage that is outside the voltage range defined by upper limit threshold value V mu  and lower limit threshold value V ml  can be restored to the voltage range by controlling the charge and discharge of power storage device  3 . 
     Furthermore, when the calculated result of the adjustment target voltage is larger than upper limit threshold value V mu , local charge and discharge device  100 A controls the operation of power storage device  3  by using the correlation information so that the adjustment target voltage is included in the range between upper limit threshold value V mu  and the upper limit value of the proper voltage range of adjustment target voltage V T . Furthermore, when the calculated result of the adjustment target voltage is smaller than lower limit threshold value V ml , local charge and discharge device  100 A controls the operation of power storage device  3  by using the correlation information so that the adjustment target voltage is included in the range between lower limit threshold value V ml  and the lower limit value of the proper voltage range of adjustment target voltage V T . 
     Therefore, a deviation from the proper voltage range of the voltage of the voltage adjustment target spot, namely, the adjustment target voltage can be reduced regardless of whether it is a low-speed component or a high-speed component, by using SVR  1 A 5  and power storage device  3 . Furthermore, voltage adjustment using power storage device  3  does not hinder the operation of SVR  1 A 5 , and therefore, switching the tap of SVR  1 A 5  can be effectively executed. Therefore, voltage adjustment that can be realized by switching the tap of SVR  1 A 5  does not have to be realized by charge and discharge of power storage device  3 , and the reactive power output of power storage device  3  can also be reduced. 
     Furthermore, in the present exemplary embodiment, period T g  of communication between local charge and discharge device  100 A and ESMS  200 A is longer than execution period T l  of charge and discharge control of power storage device  3  that is executed by local charge and discharge device  100 A, and therefore, resistance to interruption and problems in communication between local charge and discharge device  100 A and ESMS  200 A can be increased. 
     Note that while in the present exemplary embodiment, reactive power Q of power storage device  3  is controlled for the purpose of voltage adjustment, effective power P may be controlled instead of reactive power Q, or reactive power Q and effective power P may be controlled. 
     Furthermore, power storage device  3  may be interconnected under the pole transformer, or may be directly interconnected to the distribution line (however, in the case of power storage device  3  owned by a customer, reactive power output having a power factor of 0.85 or more acts as a constraint). Note that in the case of system power storage device  3 , as for the interconnection point, interconnection is desirably made at a point at which coefficient dV T /dQ becomes large, between voltage V T  of the power adjustment target spot and reactive power output Q of power storage device  3 . Furthermore, in the case of using voltage control that uses effective power P, interconnection is desirably made at a point where dV T /dP becomes large. 
     Furthermore, the method that is used to derive the correction is not limited to the mechanical learning method and other methods can be used. 
     Moreover, while the average values are used to derive the correlation function, the average values do not have to be always used. 
     Further, local charge and discharge device  100 A may be realized by a computer. In this case, the computer executes each of the functions of local charge and discharge device  100 A by reading and executing a program recorded in a computer-readable recording medium. 
     As well, ESMS  200 A may be realized by a computer. In this case, the computer executes each of the functions of ESMS  200 A has by reading and executing a program recorded in a computer-readable recording medium. 
     In the respective exemplary embodiments described above, the illustrated configurations are only examples, and the present invention is not limited to the configurations. 
     While the invention of the present application is described with reference to the exemplary embodiments, the invention of the present application is not limited to the above-described exemplary embodiments. The configuration and the details of the invention of the present application can be variously changed in such a manner that a person skilled in the art can understand within the scope of the invention of the present application. This application claims the benefit of Japanese Patent Application No. 2013-23211, filed in Japan on Feb. 8, 2013, the entire contents of which are incorporated herein by reference. 
     REFERENCE SIGNS LIST 
     
         
           1000 ,  1000 A POWER CONTROL SYSTEM 
           1  POWER SYSTEM 
           2  PHOTOVOLTAIC POWER GENERATOR 
           3  POWER STORAGE DEVICE 
           4  THERMAL POWER GENERATION EQUIPMENT 
           5  DISTRIBUTION TRANSFORMER 
           6  DISTRIBUTION LINE 
           7  LOAD 
           100  LOCAL CHARGE AND DISCHARGE DEVICE 
           101  DETECTOR 
           102  COMMUNICATOR 
           103  FREQUENCY METER 
           104  ARITHMETIC OPERATION SECTION 
           200  STORAGE BATTERY SCADA 
           201  COMMUNICATOR 
           202  DATABASE 
           203  RECOGNITION SECTION 
           204  ARITHMETIC OPERATION SECTION 
           300  CENTRAL POWER SUPPLY INSTRUCTION OFFICE 
           300 A POWER SUPPLY INSTRUCTION SECTION 
           301  FREQUENCY METER 
           302  COMMUNICATOR 
           303  ARITHMETIC OPERATION SECTION 
           1 A POWER SYSTEM 
           1 A 1  LRT 
           1 A 2  BREAKER 
           1 A 3  SWITCH 
           1 A 4  SENSOR-INCORPORATING SWITCH 
           1 A 5  SVR 
           1 A 6  POLE TRANSFORMER 
           100 A LOCAL CHARGE AND DISCHARGE DEVICE 
           101 A 1  VOLTAGE DETECTOR 
           101 A 2  EMPTY CAPACITY DETECTOR 
           101 A 3  COMMUNICATOR 
           101 A 4  ARITHMETIC OPERATION SECTION 
           200 A ESMS 
           200 A 1  COMMUNICATOR 
           200 A 2  RECOGNITION SECTION 
           200 A 3  ARITHMETIC OPERATION SECTION 
           700 A SENSOR-INCORPORATING SWITCH SLAVE STATION 
           700 A 1  VOLTAGE DETECTOR 
           700 A 2  COMMUNICATOR 
           700 A 3  ARITHMETIC OPERATION SECTION 
           700 B SVR SLAVE STATION 
           700 C SENSOR-INCORPORATING SWITCH SLAVE STATION 
           800  COMMUNICATION NETWORK