Patent Publication Number: US-2016241033-A1

Title: Control device, control method, and program

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a U.S. national stage application of International Patent Application No. PCT/JP2013/078609 filed on Oct. 22, 2013, the content of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a control device, a control method, and a program. 
     BACKGROUND 
     There is a method for suppressing power consumption of an electrical apparatus as one means for realizing a cost reduction through energy savings. A system for controlling electrical apparatuses is implemented in, for example, a building equipped with electrical apparatuses, in order to suppress power consumption of electrical apparatuses. 
     Such a system can, for example, be an energy-saving control system described in Patent Literature 1. This energy-saving control system obtains a present demand, which is an integrated value of instantaneous power up to the present time, and a change per unit time of the present demand. This energy-saving control system also predicts, from the present demand and the change per time unit of the present demand, an integrated value of the instantaneous power (power consumption amount) at an end of a predetermined time period (30 minutes). 
     This energy-saving control system, upon determining that a predicted integrated value has exceeded the integrated value (integrated value set by a user) obtained from a contract power with a power company, reduces the operation capacity of the electrical apparatuses. In this way, this energy-saving control system controls electrical apparatuses such that the actual integrated value at the end of a predetermined time period is less than or equal to the set integrated value. 
     PATENT LITERATURE 
     Patent Literature 1: Unexamined Japanese Patent Application Kokai Publication No. 2009-115392. 
     The energy-saving control system disclosed in Patent Literature 1, as previously described, predicts, from a present demand (an integrated value of instantaneous power up to the present time) and a change per time unit of the present demand, an integrated value of instantaneous power at an end of a predetermined time period (30 minutes). 
     As such, for example, when the present demand during an early stage in a predetermined time period is relatively small, this energy-saving control system determines that a predicted integrated value at the end of a time period is less than or equal to the set integrated value. This energy-saving control system accordingly, for example, conducts control causing the operation capacity of the electrical apparatuses to increase (conducts control causing power consumption of the electrical apparatuses to increase). 
     However, for example, when the present demand during an early stage in a predetermined time period is relatively large, this energy-saving control system determines that a predicted integrated value at the end of a time period exceeds a set integrated value. This energy-saving control system accordingly, for example, conducts control causing the operation capacity of the electrical apparatuses to decrease as the end of a time period draws closer, so that the actual integrated value at the end of the time period is less than or equal to the set integrated value (conducts control causing power consumption of electrical apparatuses to decrease). In particular, this energy-saving control system conducts control causing power consumption of the electrical apparatuses to drastically decrease as the end of a time period draws closer, the bigger the present demand is in an early stage in the time period. 
     In this manner, this energy-saving control system has a drawback in that a user of an electrical apparatus may be inconvenienced due insufficient leveling of power consumption of electrical apparatuses because of the energy-saving control system conducting control causing, for example, the power consumption of an electrical apparatus to drastically decrease. 
     SUMMARY 
     The present disclosure is made by taking the actual situation mentioned above into consideration, and an object of the present disclosure is to provide a control device, a control method, and a program that reduces inconvenience caused by fluctuation in operation capacity of an electrical apparatus and contributes to reducing energy consumption. 
     To achieve the foregoing objective, a first control device according to this disclosure controls an electrical apparatus so that a power consumption of the electrical apparatus during a predetermined specified time period is less than or equal to a predetermined set power. A spare power acquirer, each time a set time period shorter than the specified time period elapses, obtains an average power consumption of the electrical apparatus in the set time period and a spare power of the average power consumption with respect to a target power in the set time period that is based on the set power. An updater, when the spare power obtained by the spare power acquirer is a positive value, updates the target power in a next set time period to a power that is obtained by adding the spare power to the set power, and when the spare power obtained by the spare power acquirer is a negative value, updates the target power in the next set time period to a power that is obtained by subtracting an absolute value of the spare power from the set power, and reports the updated target power to a controller that controls the electrical apparatus. 
     Also, to achieve the forgoing objective, a second control device according to this disclosure controls an electrical apparatus so that a power consumption of the electrical apparatus during a predetermined specified time period is less than or equal to a predetermined set power. A surplus power acquirer, each time a set time period shorter than a specified time period elapses, obtains a generated power in the set time period generated by a power-generating device that causes power to be generated, and a surplus power based on the generated power. An updater, when the surplus power obtained by the surplus power acquirer is a positive value, updates the target power based on the set power in a next set time period to a power that is obtained by adding the obtained spare power to the set power, and when the surplus power obtained by the surplus power acquirer is zero, updates the target power in the next set time period to the set power, and reports the updated target power to a controller that controls the electrical apparatus. 
     According to the first control device of the present disclosure, the updater updates the target power in the next set time period to a power that is obtained by adding the spare power to the set power when the spare power obtained by the spare power acquirer is a positive value. Conversely, the updater, when the spare power obtained by the spare power acquirer is a negative value, updates the target power in the next set time period to a power obtained by subtracting an absolute value of the obtained spare power from the set power. The updater then reports the updated target power to a controller that controls the electrical apparatus. As such, the control device does not conduct control causing, for example, the power consumption of the electrical apparatus to drastically decrease as the end of the specified time period draws closer resulting in insufficient leveling of the power consumption of the electrical apparatus. Thus, the first control device reduces inconvenience caused by fluctuation in operation capacity of the electrical apparatus and contributes to reducing energy consumption. 
     According to the second control device of the present disclosure, the updater, when the surplus power obtained by the surplus power acquirer is a positive value, updates the target power based on the set power in the next set time period to a power obtained by adding the obtained surplus power to the set power. Conversely, the updater, when the surplus power obtained by the surplus power acquirer is zero, updates the target power in the next set time period to the set power. The updater then reports the updated target power to a controller that controls the electrical apparatus. As such, even if the control device causes the target power to increase, the target power does not get reduced to lower than the set power. Accordingly, the control device does not conduct control causing, for example, power consumption of the electrical apparatus to drastically decrease as the end of the specified time period draws closer resulting in insufficient leveling of the power consumption of the electrical apparatus. Thus, the second control device reduces inconvenience caused by fluctuation in operation capacity of the electrical apparatus and contributes to reducing energy consumption. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of a control system according to Embodiment 1 of the present disclosure; 
         FIG. 2A  is a diagram illustrating an average power consumption for an air conditioner of the control system according to Embodiment 1; 
         FIG. 2B  is a diagram illustrating an updating of a demand value of the control system according to Embodiment 1; 
         FIG. 3  is a diagram illustrating a demand control by a control device of the control system according to Embodiment 1; 
         FIG. 4  is a flowchart showing a demand value update process of the control system according to Embodiment 1; 
         FIG. 5  is a block diagram of a control system according to Embodiment 2 of the present disclosure; 
         FIG. 6A  is a diagram illustrating a surplus power of the control system according to Embodiment 2; 
         FIG. 6B  is a diagram illustrating an updating of a demand value of the control system according to Embodiment 2; 
         FIG. 7  is a flowchart showing a demand value update process of the control system according to Embodiment 2; 
         FIG. 8  is a block diagram of a control system according to Embodiment 3 of the present disclosure; 
         FIG. 9A  is a diagram illustrating a spare power of the control system according to Embodiment 3; 
         FIG. 9B  is a diagram illustrating a surplus power of the control system according to Embodiment 3; 
         FIG. 9C  is a diagram illustrating an updating of a demand value of the control system according to Embodiment 3; and 
         FIG. 10  is a flowchart showing a demand value update process of the control system according to Embodiment 3. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiment 1 
     An air-conditioning system  10  including a control system according to Embodiment 1 of the present disclosure is described in detail below with reference to the drawings as an example of an air-conditioning system that controls indoor temperature. 
     The air-conditioning system  10  includes multiple air conditioners  11  as an example of electrical apparatuses, as illustrated in  FIG. 1 . The air-conditioning system  10 , for example, further includes a control device  12  that controls the air conditioners  11   a  to  11   c  so that an average power consumption that is obtained based on an average value of a power consumption during a predetermined specified time period which is supplied from commercial power source to the air conditioners  11   a  to  11   c  and consumed is less than or equal to a predetermined set power. The control by this control device  12  is referred to as demand control. 
     The specified time period refers to a time period during which the control device  12  conducts demand control. Hereinafter, the specified time period is referred to as a demand time period. Also, the set power refers to an upper limit value of a power consumption allowed to be consumed by the air conditioners  11   a  to  11   c  during the demand time period. Hereinafter, the set power is referred to as a demand initial value D. 
     The air conditioners  11   a  to  11   c  each include a controller  111  that conducts overall control of the air conditioner  11 , a control target part  112  to be controlled by the controller  111 , and a wireless communication interface  113  that enables wireless communication. Each of the components  111  to  113  are connected to each other via a bus line BL. 
     The controller  111  includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and a timer. 
     The controller  111  starts counting with the timer upon reception, from the control device  12 , of a signal indicating that demand control has started while the power source of the air conditioner  11  is turned on. When the controller  111  determines, based on counting with the timer, that a set time period (3 minutes for example), which is a shorter time period than the demand time period (30 minutes for example), has elapsed, the controller  111  obtains a power consumption amount in the set time period. The controller  111  then transmits the power consumption amount in the set time period to the control device  12 . In this way, the controller  111  transmits the power consumption amount in the set time period to the control device  12  each time the set time period elapses. 
     In this embodiment, the controller  111  of each air conditioner  11   a  to  11   c  transmits to the control device  12  the power consumption amount together with a piece of identification information that can specify the air conditioner  11 . 
     The control target part  112  is, for example, a heat exchanger, an inverter circuit, and the like. 
     The wireless communication interface  113  transmits to the control device  12  a power consumption amount together with a piece of identification information. 
     Control device  12  includes a controller  121  that conducts overall control of the control device  12 , and a storage  122  that stores information that the controller  121  references. The control device  12  further includes: an inputter  123  for accepting a user input of the demand initial value D which is an initial value of a demand value described later and for accepting a demand control start instruction from the user; a display  124  for displaying the input demand initial value D; and a wireless communication interface  125  that enables wireless communication. Each of the components  121  to  125  are interconnected via a bus line BL. The demand value is a target power of the air conditioners  11   a  to  11   c  in a set time period based on the demand initial value D and is updated each time the set time period elapses. 
     The demand initial value D is input for each air conditioners  11   a  to  11   c  by, for example, a user. For example, the user inputs the demand initial value D together with a piece of identification information that can specify air conditioners  11   a  to  11   c.    
     The controller  121  includes a CPU, a ROM, and a RAM. When the inputter  123  accepts an instruction to start the demand control, the controller  121  transmits to the air conditioners  11   a  to  11   c,  a signal indicating that the demand control has started. Also, upon reception of the power consumption amount which is transmitted from the air conditioners  11   a  to  11   c,  the controller  121  stores the power consumption amount together with the piece of identification information into the RAM. 
     By executing a program (for example, a program that realizes the flowchart in  FIG. 4  described later) stored in the ROM, the CPU of the controller  121  realizes: an average power consumption acquirer  121   a  that obtains an average power consumption of the air conditioners  11   a  to  11   c  in the set time period; the spare power acquirer  121   b  that obtains a spare power of the average power consumption obtained by the average power consumption acquirer  121   a  with respect to the demand value (target power); and the updater  121   c  that updates the demand value. 
     The average power consumption acquirer  121   a  acquires from the RAM a power consumption amount which is transmitted from the air conditioners  11   a  to  11   c  for each piece of identification information (for each air conditioner  11 ). The average power consumption acquirer  121   a  then divides the acquired power consumption amount by the set time period and obtains the average power consumption of the air conditioner  11  in the set time period for each piece of identification information. 
     Each time the average power consumption is obtained by the average power consumption acquirer  121   a  (each time the set time period elapses), the spare power acquirer  121   b  subtracts the obtained average power consumption from the present demand value, and thus obtains the spare power for each piece of identification information. 
     When the spare power obtained by the spare power acquirer  121   b  is a positive value, the updater  121   c  adds the obtained spare power to the demand initial value D, and thus updates the demand value in the next set time period for each piece of identification information. 
     Conversely, when the spare power obtained by the spare power acquirer  121   b  is not a positive value (is zero or negative value), the updater  121   c  subtracts an absolute value of the obtained spare power from the demand initial value D, and thus updates the demand value in the next set time period for each piece of identification information. 
     The updating of the demand value is described in detail with reference to  FIGS. 2A and 2B . In the description of  FIGS. 2A and 2B ,a demand time period T is divided into six equal segments defined as set time periods t 1  to t 6 . The set time periods t 1  to t 6  each have the same length. 
     For example, as illustrated in  FIG. 2A , the average power consumption acquirer  121   a  obtains, as P 1  (=average power consumption in the set time period t 1 ), an average power consumption of the air conditioner  11   a  in the set time period t 1  from the power consumption amount which is transmitted from the air conditioner  11   a.  Then, the spare power acquirer  121   b  subtracts the obtained average power consumption P 1  from a demand value (a demand value of the set time period t 1  is the demand initial value D) that is together with the piece of identification information indicating the air conditioner  11   a,  and thus obtains a spare power W 1  (positive value) of the air conditioner  11   a.    
     The updater  121   c  adds the obtained spare power W 1  to the demand initial value D, and thus updates a demand value M 2  of the air conditioner  11   a  in the next set time period t 2  following the set time period t 1  to the demand initial value D+the spare power W 1 , as illustrated in  FIG. 2B . 
     The average power consumption acquirer  121   a  also, for example, obtains, as P 3 , an average power consumption of the air conditioner  11   a  in the set time period t 3  from the power consumption amount which is transmitted from the air conditioner  11   a,  as illustrated in  FIG. 2A . Then, the spare power acquirer  121   b  subtracts the obtained average power consumption P 3  from a demand value M 3  of the air conditioner  11   a  in the set time period t 3 , and thus obtains a negative value of a spare power W 3 . 
     Then, the updater  121   c  subtracts an absolute value of the spare power W 3  from the demand initial value D, and thus updates a demand value M 4  of the air conditioner  11   a  in the next set time period t 4  following the set time period t 3  to the demand initial value D−the absolute value of the spare power W 3  as illustrated in  FIG. 2B . 
     Also, the average power consumption acquirer  121   a  obtains, as P 5 , an average power consumption of the air conditioner  11   a  in the set time period t 5  from the power consumption amount which is transmitted by the air conditioner  11   a,  as illustrated in  FIG. 2A . Then, the spare power acquirer  121   b  subtracts the obtained average power consumption P 5  from a demand value M 5  of the air conditioner  11   a  in the set time period t 5  and obtains a positive spare power W 5 . 
     The updater  121   c  adds the obtained spare power W 5  to the demand initial value D, and thus updates a demand value M 6  of the air conditioner  11   a  in the next set time period t 6  following the set time period t 5  to the demand initial value D+the spare power W 5 , as illustrated in  FIG. 2B . 
     By performing the above-described process also for the air conditioners  11   b  and  11   c,  the controller  121  updates the demand value each time the set time period elapses during the demand time period. Upon updating the demand value, the controller  121  obtains a rated power capacity ratio of the air conditioner  11  based on the updated demand value. The controller  121  then transmits to the air conditioner  11   a  control signal indicating the rated power capacity ratio. 
     Upon reception of the control signal, the controller  111  of the air conditioner  11  operates with the rated power capacity ratio instructed by the control signal, set as a target (standard). 
     In this way, the control device  12  controls the air conditioner  11  so that the average power consumption in the demand time period which is supplied to the air conditioner  11  from, for example, a commercial power source, and consumed, is less than or equal to the demand initial value D. 
     For example, as illustrated in  FIG. 3 , the rated power of the air conditioner  11  is 20 kW, the demand initial value D is 8 kW, and the updated demand value is 10 kW as a result of a positive value of the obtained spare power. Then, the controller  121  obtains a rated power capacity ratio of 0.5 so that the power consumption of the air conditioner  11  is 10 kW. The controller  121  then transmits (reports) to the air conditioner  11   a  control signal indicating that the rated power capacity ratio is 0.5. 
     Upon reception of the control signal, the controller  111  of the air conditioner  11  operates with the rated power capacity ratio of 0.5 instructed by the control signal, set as the target. 
     Subsequently, as the set time period elapses again, the controller  121  determines that the updated demand value is 6 kW as a result of a negative value of the obtained spare power. Then, the controller  121  obtains a rated power capacity ratio of 0.3 so that the power consumption of the air conditioner  11  is 6 kW. The controller  121  then transmits (reports) to the air conditioner  11   a  control signal indicating the rated power capacity ratio of 0.3. 
     Upon reception of the control signal, the controller  111  of the air conditioner  11  operates with the rated power capacity ratio of 0.3 instructed by the control signal, set as the target. 
     Referring back to the description of  FIG. 1 . The storage  122  includes a flash memory for example. The storage  122  includes a demand initial value storage  122   a  that stores a demand initial value D, and a demand value storage  122   b  that stores a present demand value. 
     When the demand initial value D and a piece of identification information are input by a user operation through the inputter  123 , the controller  121  stores the input demand initial value D together with the piece of identification information into the demand initial value storage  122   a.    
     The demand value stored into the demand value storage  122   b  is the same value as the demand initial value D until the demand control by the control device  12  starts. As such, when the demand initial value D is input by the user operation through the inputter  123 , the controller  121  also stores the input demand initial value D into the demand value storage  122   b.    
     When the control device  12  starts the demand control, the controller  121  updates the demand value each time the set time period elapses. The controller  121  stores the updated demand value together with the piece of identification information into the demand value storage  122   b.  The controller  121  obtains the rated power capacity ratio of the air conditioner  11  based on the demand value stored in the demand value storage  122   b.    
     The inputter  123  is a keyboard for example. The display  124  is a liquid crystal display for example 
     The wireless communication interface  125  receives a power consumption amount which is transmitted from the air conditioner  11 . Also, the wireless communication interface  125  transmits a control signal to the air conditioner  11 . 
     The controller  121  of the control device  12  obtains the rated power capacity ratio of the air conditioner  11  based on the demand initial value D stored in the demand value storage  122   b  when starting of the demand control by the control device  12  is instructed from a user while the power sources of the above-described air conditioner  11  and control device  12  are turned on. The controller  121  then transmits to the air conditioner  11   a  control signal indicating the rated power capacity ratio. 
     Upon reception of the control signal, each controller  111  of the air conditioners  11   a  to  11   c  operates with the rated power capacity ratio instructed by the control signal, set as the target. Each controller  111  of the air conditioners  11   a  to  11   c  then transmits a power consumption amount in the set time period to the control device  12  as the set time period elapses. 
     Upon reception of the power consumption amount in the set time period from each of the air conditioners  11   a  to  11   c,  the control device  12  executes a demand value update process as illustrated in  FIG. 4  in response to an interrupt signal indicating that the power consumption amount was received. The demand value update process is a timer-interrupt process. 
     In the demand value update process, the controller  121  (the average power consumption acquirer  121   a ) acquires from the RAM a power consumption amount in the set time period which is transmitted from the air conditioner  11 , divides the power consumption amount by the set time period, and then obtains an average power consumption of the air conditioner  11  in the set time period for each piece of identification information (for each air conditioner  11 ) (step S 1 ). 
     Next, the controller  121  (the spare power acquirer  121   b ) subtracts the average power consumption obtained in step Si from the demand value stored in the demand value storage  122   b,  and thus obtains a spare power for each piece of identification information (step S 2 ). When the demand value stored in the demand value storage  122   b  is not yet updated, the demand value is the demand initial value D. 
     For example, as illustrated in  FIGS. 2A and 2B , when the average power consumption of the air conditioner  11   a,  which is obtained in step Si in the set time period t 1 , is P 1 , and the demand value, which is stored in demand value storage  122   b,  is the demand initial value D, the controller  121  (the spare power acquirer  121   b ) obtains the spare power of the air conditioner  11   a  as a positive value W 1  (=D−P 1 ). 
     Also, for example, as illustrated in  FIGS. 2A and 2B , when the average power consumption of the air conditioner  11   a,  which is obtained in step S 1  in the set time period t 3 , is P 3 , and the demand value, which is stored in the demand value storage  122   b,  is M 3 , the controller  121  (the spare power acquirer  121   b ) obtains a negative spare power (=M 3 −P 3 ). 
     After step S 2 , illustrated in  FIG. 4 , the controller  121  (the updater  121   c ) determines whether the spare power is greater than zero (positive or negative) for each piece of identification information (step S 3 ). 
     When the spare power is equal to or less than zero, that is to say, when the spare power is zero or a negative value, this is indication that the average power consumption of the air conditioner  11  is greater than or equal to the present demand value. In this case, the controller  121  (the updater  121   c ) determines No in step S 3  for the piece of identification information that is together with the spare power indicating zero or a negative value. The controller  121  (the updater  121   c ) then updates the demand value to a value obtained by subtracting an absolute value (including zero) of the spare power from the demand initial value D which is stored in the demand initial value storage  122   a  (step S 6 ). 
     For example, as illustrated in  FIG. 2B , in the set time period t 3 , when the spare power of the air conditioner  11   a  obtained in step S 2  is the negative value W 3 , the controller  121  subtracts an absolute value of the spare power W 3  from the demand initial value D, and then updates the demand value M 4  of the air conditioner  11   a  in the set time period t 4  to D−W 3 . 
     After step S 3  illustrated in  FIG. 4 , the controller  121  (the updater  121   c ) stores the updated demand value into the demand value storage  122   b  (step S 5 ) and thereby completes the demand value update process. 
     Conversely, when the value of the spare power is greater than zero, the average power consumption of the air conditioner  11  is less than the present demand value, and this is indication that there is a spare power. In this case, the controller  121  (the updater  121   c ) determines Yes in step S 3  for the piece of identification information that is together with the spare power that exceeds zero. The controller  121  (the updater  121   c ) then updates the demand value to a value obtained by adding the spare power obtained in step S 2  to the demand initial value D which is stored in the demand initial value storage  122   a  (step S 4 ). 
     For example, as illustrated in  FIG. 2B , when the spare power of the air conditioner  11   a  obtained in step S 2  is the positive value W 1  in the set time period t 1 , the controller  121  adds the spare power W 1  to the demand initial value D, and then increases the demand value M 2  of the air conditioner  11   a  in the set time period t 2  to D+W 1 . 
     After step S 4  illustrated in  FIG. 4 , the controller  121  (the updater  121   c ) stores the updated demand value into the demand value storage  122   b  for each piece of identification information (step S 5 ) and thereby completes the demand value update process. 
     The controller  121  then obtains a rated power capacity ratio of the air conditioner  11  based on the demand value (the updated demand value) stored in the demand value storage  122   b.  The controller  121  then transmits to the air conditioner  11  a control signal indicating the rated power capacity ratio. 
     Upon reception of the control signal, the controller  111  of the air conditioner  11  operates with the rated power capacity ratio instructed by the control signal, set as the target. 
     As described above, when a spare power is generated, the control device  12  adds the spare power to the demand initial value D, and then updates the demand value in the next set time period. Conversely, when the spare power is negative, the control device  12  subtracts an absolute value of the negative spare power from the demand initial value D, and then updates the demand value in the next set time period. 
     As such, the control device  12  does not conduct control causing, for example, the power consumption of the air conditioner  11  to drastically decrease as the end of the specified time period draws closer resulting in insufficient leveling of the power consumption of the air conditioner  11 . Thus, the air-conditioning system  10  of Embodiment 1 reduces inconvenience caused by fluctuation in operation capacity of the air conditioner  11  and contributes to reducing energy consumption. 
     Embodiment 2 
     As previously described, in Embodiment 1, the demand value is increased based on the actual power consumption in the previous set time period. 
     However, this disclosure is not limited to this example and when a suppliable power fluctuates, the demand value may be increased based on the actual power supply on the power-supplying side instead of the actual power consumption on the power-consuming side. 
     An air-conditioning system  20  of Embodiment 2, illustrated in  FIGS. 5 to 7 , obtains a surplus power based on a generated power in the set time period of a photovoltaic apparatus, adds the surplus power to the demand initial value D, and then increases the demand value in the set time period. 
     Hereafter, the air-conditioning system  20  of Embodiment 2 is described with reference to  FIGS. 5 to 7 . The components described here that are the same as those in the air-conditioning system  10  of Embodiment 1 are given the same reference numbers. 
     The air-conditioning system  20  that includes a control system set forth in Embodiment 2 of the present disclosure, as illustrated in  FIG. 5 , includes, in addition to the air conditioners  11  and the control device  12 , a photovoltaic apparatus  31  that generates power by converting sunlight energy into electricity. 
     The photovoltaic apparatus  31  starts counting with a timer upon reception, from the control device  12 , of a signal indicating that demand control has started while the power source of the air conditioner  11  is turned on. When the photovoltaic apparatus  31  determines, based on counting with the timer, that a set time period (3 minutes for example), which is a shorter time period than a demand time period (30 minutes for example), has elapsed, the photovoltaic apparatus  31  obtains a generated power amount in the set time period. The photovoltaic apparatus  31  then transmits the generated power amount in the set time period to the control device  12 . In this way, the photovoltaic apparatus  31  transmits the generated power amount in the set time period to the control device  12  each time the set time period elapses. 
     Upon reception of the generated power amount which is transmitted from the photovoltaic apparatus  31 , the controller  121  of the control device  12  stores the generated power amount into the RAM. 
     The CPU of the controller  121  executes a program (for example, a program that realizes the flowchart in  FIG. 7  described later) stored in the ROM. Accordingly, the CPU of the controller  121  realizes: an updater  121   c  that updates the demand value; and a surplus power acquirer  121   d  that obtains the surplus power based on the generated power by the photovoltaic apparatus  31  in the set time period. 
     The surplus power acquirer  121   d  acquires from the RAM the generated power amount which is transmitted from the photovoltaic apparatus  31  and divides the generated power amount by the set time period. The surplus power acquirer  121   d  then obtains the generated power by the photovoltaic apparatus  31  in the set time period. 
     The surplus power acquirer  121   d  divides the obtained generated power by the number of units of the air conditioner  11  (distributes the surplus power among each of the air conditioners  11 ), and thus obtains the surplus power. The surplus power acquirer  121   d  then multiplies the obtained surplus power by a predetermined coefficient, and thus obtains the surplus power in the set time period. The coefficient in this embodiment is 1.0. 
     When the surplus power obtained by the surplus power acquirer  121   d  is a positive value, the updater  121   c  adds the surplus power to the demand initial value D that is together with each piece of identification information, and thus updates the demand value for each piece of identification information each time the set time period elapses. 
     Conversely, when the surplus power obtained by the surplus power acquirer  121   d  is zero, the updater  121   c  sets the demand initial value D as the demand value that is together with each piece of identification information. 
     The updating of the demand value is described in detail with reference to  FIGS. 6A and 6B . In the description of  FIGS. 6A and 6B , the demand time period T is divided into six equal segments defined as set time periods t 1   a  to t 6   a.  The set time periods t 1   a  to t 6   a  each have the same length. 
     For example, as illustrated in  FIG. 6A , the surplus power acquirer  121   d  obtains, as Q 1 , a generated power in the set time period t 1   a  from the generated power amount which is transmitted from the photovoltaic apparatus  31 . The surplus power acquirer  121   d  then divides the generatd power Q 1  by three, which is the number of units of the air conditioner  11 , and thus obtains a surplus power Q 1 / 3 . Then, the updater  121   c  adds the surplus power Q 1 / 3  to the demand initial value D of the air conditioner  11   a,  and thus increases the demand value M 2  of the air conditioner  11   a  in the next set time period t 2   a  following the set time period t 1   a  to D+Q 1 / 3 , as illustrated in  FIG. 6B . 
     Also, for example, as illustrated in  FIG. 6A , the surplus power acquirer  121   d  obtains, as zero, a surplus power Q 3  in the set time period t 3   a  from the generated power amount which is transmitted from the photovoltaic apparatus  31 . Then, the updater  121   c  sets the demand value M 4  of the air conditioner  11   a  in the next set time period t 4   a  following the set time period t 3   a  to the demand initial value D, as illustrated in  FIG. 6B . 
     Also, for example, as illustrated in  FIG. 6A , the surplus power acquirer  121   d  obtains, as Q 5 , a generated power in the set time period t 5   a  from the power-generation amount which is transmitted from the photovoltaic apparatus  31 . The surplus power acquirer  121   d  then divides the obtained generated power Q 5  by three, which is the number of units of the air conditioner  11 , and thus obtains a surplus power Q 5 / 3 . Then, the updater  121   c  adds the surplus power Q 5 / 3  to the demand initial value D of the air conditioner  11   a,  and thus increases the demand value M 6  of the air conditioner  11   a  in the next set time period t 6   a  following the set time period t 5   a  to D+Q 5 / 3 , as illustrated in  FIG. 6B . 
     By performing this process also for the air conditioners  11   b  and  11   c,  the controller  121  updates the demand value during the demand time period. Upon updating of the demand value, the controller  121  obtains an upper limit value for the rated power capacity ratio of the air conditioner  11  based on the updated demand value. Then, the controller  121  transmits (reports) a control signal indicating the upper limit value for the rated power capacity ratio to the air conditioner  11 . 
     Upon reception of the control signal, the controller  111  of the air conditioner  11  operates with the rated power capacity ratio value instructed by the control signal, set as the upper limit. 
     In this manner, the control device  12  sets the demand initial value D as the lower limit The control device  12 , when there is a surplus power, increases the demand value in the next set time period, and when there is no surplus power, sets the demand initial value D as the demand value of the next set time period. In this way, the control device  12  controls the air conditioner  11  so that the average power consumption in the demand time period which is supplied to the air conditioner  11  from, for example, a commercial power source, and consumed, is less than or equal to the demand initial value D. 
     The controller  121  of the control device  12  obtains the upper limit value for the rated power capacity ratio of the air conditioner  11  based on the demand initial value D stored in the demand value storage  122   b  when starting of the demand control by the control device  12  is instructed from a user while the power sources of the above-described air conditioner  11  and control device  12  are turned on, and the photovoltaic apparatus  31  is in a power-generation-capable state. The controller  121  then transmits a control signal indicating the upper limit value for the rated power capacity ratio to the air conditioner  11 . 
     Upon reception of the control signal, each controller  111  of the air conditioners  11   a  to  11   c  operates with the upper limit value for the rated power capacity ratio instructed by the control signal, set as the upper limit 
     Also, the photovoltaic apparatus  31  transmits the generated power amount in the set time period to the control device  12  as the set time period elapses. 
     Upon reception of the generated power amount in the set time period from the photovoltaic apparatus  31 , the control device  12  executes a demand value update process illustrated in  FIG. 7  in response to an interrupt signal indicating that the generated power amount was received. The demand value update process is a timer-interrupt process. 
     In the demand value update process, the controller  121  (the surplus power acquirer  121   d ) acquires from the RAM a generated power amount which is transmitted from the photovoltaic apparatus  31 , divides the generated power amount by the set time period, and then obtains a generated power of the photovoltaic apparatus  31  in the set time period (step S 11 ). Then, the controller  121  (the surplus power acquirer  121   d ) obtains a value distributed among each of air conditioner  11  from the obtained generated power, multiplies the value by the predetermined coefficient (1.0), and then obtains a surplus power in the set time period (step S 11 ). 
     The controller  121  (the updater  121   c ) then determines whether the obtained surplus power exceeds zero (whether a positive value or not) (step S 12 ). 
     When the surplus power exceeds zero, this is indication that there is a surplus power. In this case, the controller  121  (the updater  121   c ) determines Yes in step S 12 . The controller  121  (the updater  121   c ) adds the obtained surplus power to the demand initial value D for each piece of identification information stored in the demand initial value storage  122   a  and thus increases each demand value in the next set time period (step S 13 ). 
     In step S 13 , for example, as illustrated in  FIGS. 6A and 6B , when the obtained generated power in the set time period t 1   a  is Q 1  and the demand initial value of the air conditioner  11   a  which is stored in the demand initial value storage  122   a  is D, the controller  121  (the updater  121   c ) adds the surplus power Q 1 / 3  to the demand initial value D, and then increases the demand value M 2  in the next set time period t 2   a  of the air conditioner  11   a  to D+Q 1 / 3 . 
     After step S 13 , the controller  121  (the updater  121   c ) stores the updated demand value into the demand value storage  122   b  (step S 14 ) and thereby completes the demand value update process. 
     Conversely, when the surplus power does not exceed zero, that is to say, when the surplus power is zero, this is indication that there is no surplus power. In this case, the controller  121  (the updater  121   c ) determines No in step S 12 . The controller  121  (the updater  121   c ) then updates the demand value for each piece of identification information (each demand value in the next set time period) to the demand initial value (step S 15 ). 
     The controller  121  (the updater  121   c ) then stores the updated demand value into the demand value storage  122   b  (step S 14 ) and thereby completes the demand value update process. 
     The controller  121  then obtains an upper limit value of the rated power capacity ratio of the air conditioner  11  based on the demand value (the updated demand value) which is stored in the demand value storage  122   b.  The controller  121  then transmits a control signal indicating the upper limit value of the rated power capacity ratio to the air conditioner  11 . 
     Upon reception of the control signal, the controller  111  of the air conditioner  11  operates with the upper limit value for the rated power capacity ratio instructed by the control signal, set as the upper limit. 
     As described above, when the photovoltaic apparatus  31  is generating power, the control device  12  adds the distributed surplus power to the demand initial value D, and then increases the demand value in the next set time period. Conversely, when the photovoltaic apparatus  31  is not generating power, the control device  12  sets the demand initial value D as the demand value in the next set time period. 
     As such, during the demand time period, although the control device  12  conducts control causing the demand value to increase, the control device  12  does not conduct control causing the demand value to decrease to a value lower than the demand initial value D. Accordingly, the control device  12  does not conduct control causing, for example, the power consumption of the air conditioner  11  to drastically decrease as the end of the specified time period draws closer resulting in insufficient leveling of the power consumption of the air conditioner  11 . Thus, the air-conditioning system  20  of Embodiment 2 reduces inconvenience caused by fluctuation in operation capacity of the air conditioner  11  and contributes to reducing energy consumption. 
     Embodiment 3 
     As previously described, in the air-conditioning system  10  of Embodiment 1 the average power consumption of the air conditioners  11  in the set time period is subtracted from the present demand value to obtain the spare power, and when there is a spare power, the spare power is added to the demand initial value D and then the demand value is increased. Also, in the air-conditioning system  20  of Embodiment 2, when the photovoltaic apparatus  31  is generating power, the surplus power distributed from the generated power is obtained, the obtained surplus power is added to the demand initial value D, and then the demand value is increased. 
     However, this disclosure is not limited to these examples, and when a suppliable power fluctuates, the demand value may be updated based on the actual power supply on the power-supplying side and actual power consumption on the power-consuming side. 
     An air-conditioning system  30  of Embodiment 3 illustrated in  FIGS. 8 to 10 , when there is both spare power and surplus power, adds the spare power and surplus power to the demand initial value D, and then increases the demand value in the next set time period. 
     The air-conditioning system  30  of Embodiment 3 is described below with reference to  FIGS. 8 to 10 . The components described here that are the same as those in the air-conditioning system  10  of Embodiment 1 and the air-conditioning system  20  of Embodiment 2 are given the same reference numbers. 
     The air-conditioning system  30  that includes a control system set forth in Embodiment 3 of the present disclosure, as illustrated in  FIG. 8 , includes the air conditioners  11 , the control device  12  and the photovoltaic apparatus  31 . 
     The controller  111  of the air conditioner  11  starts counting with the timer upon reception, from the control device  12 , of a signal indicating that demand control has started while the power source of the air conditioner  11  is turned on. When the controller  111  determines that a set time period (3 minutes for example) has elapsed based on counting with the timer, the controller  111  obtains a power consumption amount in the set time period. The controller  111  then transmits to the control device  12  the power consumption amount in the set time period. 
     Upon reception of the power consumption amount which is transmitted from the air conditioner  11 , the controller  121  of the control device  12  stores the power consumption amount together with a piece of identification information into the RAM. 
     The photovoltaic apparatus  31  starts counting with the timer upon reception, from the control device  12 , of a signal indicating that demand control has started while the power source of the air conditioner  11  is turned on. Upon determining that the set time period (3 minutes for example) has elapsed based on counting with the timer, the photovoltaic apparatus  31  obtains a generated power amount in the set time period. The photovoltaic apparatus  31  then transmits to the control device  12  the generated power amount in the set time period. 
     Upon reception of the generated power amount which is transmitted from the photovoltaic apparatus  31 , the controller  121  of the control device  12  stores the generated power amount into the RAM. 
     The CPU of the controller  121  executes a program (for example, a program that realizes the flowchart in  FIG. 10  described later) stored in the ROM. Accordingly, the CPU of the controller  121  realizes: the average power consumption acquirer  121   a  that obtains an average power consumption of air conditioners  11   a  to  11   c  in the set time period; and the spare power acquirer  121   b  that obtains a spare power of the average power consumption obtained by the average power consumption acquirer  121   a  with respect to the demand value. The CPU of the controller  121  also realizes the updater  121   c  that updates the demand value and the surplus power acquirer  121   d  that obtains a surplus power based on a generated power of the photovoltaic apparatus  31  in the set time period. 
     The average power consumption acquirer  121   a  acquires from the RAM a power consumption amount which is transmitted from the air conditioners  11   a  to  11   c  for each piece of identification information (for each air conditioner  11 ). Also, the average power consumption acquirer  121   a  divides the acquired power consumption amount by the set time period and obtains the average power consumption of the air conditioner  11  in the set time period for each piece of identification information. 
     Each time the average power consumption is obtained by the average power consumption acquirer  121   a  (each time the set time period elapses), the spare power acquirer  121   b  subtracts the obtained average power consumption from the present demand value, and thus obtains the spare power for each piece of identification information. 
     The surplus power acquirer  121   d  acquires from the RAM a generated power amount which is transmitted from the photovoltaic apparatus  31 , and divides the generated power amount by the set time period. The surplus power acquirer  121   d  then obtains the generated power of the photovoltaic apparatus  31  in the set time period. 
     The surplus power acquirer  121   d  then divides the obtained generated power by the number of units of the air conditioner  11  (distributes the surplus power values among each of the air conditioners  11 ), and thus obtains the surplus power. The surplus power acquirer  121   d  then multiplies the obtained surplus power by a predetermined coefficient, and thus obtains the surplus power in the set time period. The coefficient in this embodiment is 1.0. 
     When the spare power obtained by the spare power acquirer  121   b  is a positive value, the updater  121   c  adds the obtained spare power and the surplus power (including zero) obtained by the surplus power acquirer  121   d  to the demand initial value D, and thus updates the demand value in the next set time period. 
     Conversely, when the spare power obtained by the spare power acquirer  121   b  is not a positive value (when zero or a negative value), the updater  121   c  updates the demand value in the next set time period to a power obtained by subtracting an absolute value (including zero) of the spare power from the demand initial value D, and then adding the surplus power (including zero) obtained by the surplus power acquirer  121   d.    
     The updating of the demand value is described in detail with reference to  FIGS. 9A, 9B, and 9C . In the description of  FIGS. 9A, 9B, and 9C , the demand time period T is divided into six equal segments defined as set time periods t 1   b  to t 6   b.  The set time periods t 1   b  to t 6   b  each have the same length. 
     For example, as illustrated in  FIG. 9A , the average power consumption acquirer  121   a  obtains, as P 1 , an average power consumption of the air conditioner  11   a  in the set time period t 1   b  from the power consumption amount which is transmitted from the air conditioner  11   a.  Then, the spare power acquirer  121   b  subtracts the obtained average power consumption P 1  from the demand value M 1  (the demand value of the set time period t 1   b  is the demand initial value D) that is together with the piece of identification information indicating the air conditioner  11   a,  and thus obtains a spare power W 1  (positive value) of the air conditioner  11   a.    
     Also, as illustrated in  FIG. 9B , the surplus power acquirer  121   d  obtains, as Q 1  (positive value), a generated power in the set time period t 1   b  from the generated power amount which is transmitted from the photovoltaic apparatus  31 . The surplus power acquirer  121   d  then divides the generated power Q 1  by three, which is the number of units of the air conditioner  11 , and thus obtains a surplus power Q 1 / 3 . 
     Then, the updater  121   c  adds the surplus power Q 1 / 3  and the obtained spare power W 1  to the demand initial value D of the air conditioner  11   a , and thus updates the demand value M 2  of the air conditioner  11   a  in the next set time period t 2   b  following the set time period t 1   b  to the demand initial value D+W 1 +Q 1 / 3 , as illustrated in  FIG. 9C . 
     Also, for example, as illustrated in  FIG. 9A , the average power consumption acquirer  121   a  obtains, as P 2 , an average power consumption of the air conditioner  11   a  in the set time period t 2   b  from the power consumption amount which is transmitted from the air conditioner  11 . Then, the spare power acquirer  121   b  subtracts the obtained average power consumption P 2  from the demand value M 2  that is together with the piece of identification information indicating the air conditioner  11   a,  and thus obtains a positive value of a spare power W 2 . 
     Also, as illustrated in  FIG. 9B , the surplus power acquirer  121   d  obtains, as Q 2  (positive value), a generated power in the set time period t 2   b  from the generated power amount which is transmitted from the photovoltaic apparatus  31 . The surplus power acquirer  121   d  then divides the generated power Q 2  by three, which is the number of units of the air conditioner  11 , and thus obtains a surplus power Q 2 / 3 . 
     Then, the updater  121   c  adds the surplus power Q 2 / 3  and the obtained spare power W 2  to the demand initial value D of the air conditioner  11   a,  and thus updates the demand value M 3  of the air conditioner  11   a  in the next set time period t 3   b  following the set time period t 2   b  to the demand initial value D+W 2 +Q 2 / 3 , as illustrated in  FIG. 9C . 
     Also, for example, as illustrated in  FIG. 9A , the average power consumption acquirer  121   a  obtains, as P 3 , an average power consumption of the air conditioner  11   a  in the set time period t 3   b  from the power consumption amount which is transmitted from the air conditioner  11 . Then, the spare power acquirer  121   b  subtracts the obtained average power consumption P 3  from the demand value M 3  that is together with the piece of identification information indicating the air conditioner  1  la, and thus obtains a positive value of a spare power W 3 . 
     Also, as illustrated in  FIG. 9B , the surplus power acquirer  121   d  obtains, as zero, a generated power Q 3  in the set time period t 3   b  from the generated power amount which is transmitted from the photovoltaic apparatus  31 . As a result, the surplus power acquirer  121   d  obtains zero surplus power. 
     Then, the updater  121   c  adds the zero surplus power and the obtained spare power W 3  to the demand initial value D of the air conditioner  11   a,  and thus updates the demand value M 4  of the air conditioner  11   a  in the next set time period t 4   b  following the set time period t 3   b  to the demand initial value D+W 3  as illustrated in  FIG. 9C . 
     Also, for example, as illustrated in  9 A, the average power consumption acquirer  121   a  obtains, as P 4 , an average power consumption of the air conditioner  11   a  in the set time period t 4   b  from the power consumption amount which is transmitted from the air conditioner  11 . Then, the spare power acquirer  121   b  subtracts the obtained average power consumption P 4  from the demand value M 4  that is together with the piece of identification information indicating the air conditioner  11   a,  and then obtains, as zero, a spare power. 
     Also, as illustrated in  FIG. 9B , the surplus power acquirer  121   d  obtains, as zero, a generated power Q 4  in the set time period t 4   b  from the generated power amount which is transmitted from the photovoltaic apparatus  31 . As a result, the surplus power acquirer  121   d  obtains zero surplus power. 
     Then, the updater  121   c  adds the zero surplus power and the zero spare power to the demand initial value D of the air conditioner  11   a,  and then updates the demand value M 5  of the air conditioner  11   a  in the next set time period t 5   b  following the set time period t 4   b  to the demand initial value D as illustrated in  FIG. 9C . 
     Also, for example, as illustrated in  FIG. 9A , the average power consumption acquirer  121   a  obtains, as P 5 , an average power consumption of the air conditioner  11   a  in the set time period t 5   b  from the power consumption amount which is transmitted from the air conditioner  11 . Then, the spare power acquirer  121   b  subtracts the obtained average power consumption P 5  from the demand value M 5  that is together with the piece of identification information indicating the air conditioner  11   a,  and thus obtains a negative value of a spare power W 5 . 
     Also, as illustrated in  FIG. 9B , the surplus power acquirer  121   d  obtains, as Q 5  (positive value), a generated power in the set time period t 2   b  from the generated power amount which is transmitted from the photovoltaic apparatus  31 . The surplus power acquirer  121   d  then divides the generated power Q 5  by three, which is the number of units of the air conditioner  11 , and thus obtains a surplus power Q 5 / 3 . 
     Then, the updater  121   c  subtracts an absolute value of the spare power W 5  from the demand initial value D of the air conditioner  11   a,  then, to that obtained value, adds the surplus power Q 5 / 3 , and then updates the demand value M 6  of the air conditioner  11   a  in the next set time period t 6   b  following the set time period t 5   b  to the demand initial value D−W 5  (absolute value) +Q 5 / 3  as illustrated in  FIG. 9C . 
     By performing this process also for the air conditioners  11   b  and  11   c,  the controller  121  updates the demand value during the demand time period. Upon updating of the demand value, the controller  121  obtains the rated power capacity ratio of the air conditioner  11  based on the updated demand value. The controller  121  then transmits (reports) to the air conditioner  11   a  control signal indicating the rated power capacity ratio. 
     Upon reception of the control signal, the controller  111  of the air conditioner  11  operates with the rated power capacity ratio instructed by the control signal, set as the target (standard). 
     In this way, the control device  12  controls the air conditioner  11  so that the average power consumption in the demand time period which is supplied to the air conditioner  11  from, for example, a commercial power source, and consumed, is less than or equal to the demand initial value D. 
     The controller  121  of the control device  12  obtains the rated power capacity ratio of the air conditioner  11  based on the demand initial value D stored in the demand value storage  122   b  when starting of demand control by the control device  12  is instructed from a user while the power sources of the above-described air conditioner  11  and control device  12  are turned on, and the photovoltaic apparatus  31  is in a power-generation-capable state. The controller  121  then transmits to the air conditioner  11   a  control signal indicating the rated power capacity ratio. 
     Upon reception of the control signal, each controller  111  of the air conditioners  11   a  to  11   c  operates with the rated power capacity ratio instructed by the control signal, set as the target. Each controller  111  of the air conditioners  11   a  to  11   c  then transmits the power consumption amount in the set time period to the control device  12  as the set time period elapses. 
     Also, the photovoltaic apparatus  31  transmits the power-generation amount in the set time period to the control device  12  as the set time period elapses. 
     Upon reception of the power consumption amount in the set time period from each of the air conditioners  11   a  to  11   c  and reception of the generated power amount in the set time period from the photovoltaic apparatus  31 , the control device  12  executes a demand value update process illustrated in  FIG. 10  in response to an interrupt signal indicating that the power consumption amount and the generated power amount were received. The demand value update process is a timer-interrupt process. 
     In the demand value update process, the controller  121  (the surplus power acquirer  121   d ) acquires from the RAM a generated power amount which is transmitted from the photovoltaic apparatus  31 , divides the generated power amount by the set time period, and then obtains a generated power of the photovoltaic apparatus  31  in the set time period (step S 21 ). The controller  121  (the surplus power acquirer  121   d ) then divides the generated power by 3, which is the number of units of the air conditioner  11 , and then obtains a surplus power in the set time period (step S 21 ). 
     Next, the controller  121  (the average power consumption acquirer  121   a ) obtains from the RAM a power consumption amount which is transmitted from the air conditioner  11 , divides the power consumption amount by the set time period and obtains an average power consumption of the air conditioner  11  in the set time period for each piece of identification information (for each air conditioner) (step S 22 ). 
     Next, the controller  121  (the spare power acquirer  121   b ) subtracts the average power consumption obtained in step S 22  from the demand value stored in the demand value storage  122   b,  and thus obtains a spare power for each piece of identification information (step S 23 ). When the demand value stored in the demand value storage  122   b  is not yet updated, the demand value is the demand initial value D. 
     The controller  121  (the updater  121   c ) then determines whether the spare power exceeds zero for each piece of identification information (step S 24 ). 
     When the spare power exceeds zero, this is indication that there is a spare power. As such, the controller  121  (the updater  121   c ) determines Yes in step S 24  for the piece of identification information that is together with the spare power that exceeds zero. 
     The controller  121  (the updater  121   c ) then adds the surplus power obtained in step S 21  and the spare power obtained in step S 23  to the demand initial value D stored in the demand initial value storage  122   a,  and thus updates the demand value in the next set time period (step S 25 ). 
     Conversely, when the spare power does not exceed zero, that is to say, when the spare power is zero or a negative value, the controller  121  (the updater  121   c ) determines No in step S 24  for the piece of identification information that is together with the spare power indicating zero or a negative value. 
     Next, the controller  121  (the updater  121   c ) subtracts an absolute value of the spare power (including zero) obtained in step S 23  from the demand initial value D stored in the demand initial value storage  122   a,  adds to that obtained value the surplus power obtained in step S 21 , and then updates the demand value in the next time period (step S 26 ). 
     After executing the process in step S 25  or step S 26 , the controller  121  (the updater  121   c ) stores the updated demand value together with a piece of identification information into the demand value storage  122   b  (step S 27 ) and thereby completes the demand value update process. 
     The controller  121  then obtains the rated power capacity ratio of the air conditioner  11  based on the demand value (the updated demand value) stored in the demand value storage  122   b.  Thereafter, the controller  121  transmits to the air conditioner  11   a  control signal indicating the rated power capacity ratio. 
     Upon reception of the control signal, the controller  111  of the air conditioner  11  operates with the rated power capacity ratio instructed by the control signal, set as the target. 
     As described above, when a spare power is generated, the control device  12  adds the spare power and the surplus power to the demand initial value D, and then updates the demand value in the next time period. Also, when the spare power indicates zero or a negative value, the control device  12  updates the demand value in the next time period by subtracting an absolute value of the spare power from the demand initial value D, and then adding the surplus power. 
     As such, the control device  12  does not conduct control causing, for example, the power consumption of the air conditioner  11  to drastically decrease as the end of the specified time period draws closer resulting in insufficient leveling of the power consumption of the air conditioner  11 . Thus, the air-conditioning system  30  of Embodiment 3 reduces inconvenience caused by fluctuation in operation capacity of the air conditioner  11  and contributes to reducing energy consumption. 
     While the embodiments of the present disclosure are described, this disclosure is not limited to such embodiments, and various modifications and applications are possible. 
     In the air-conditioning system  10  of Embodiment 1 and the air-conditioning system  30  of Embodiment 3 described above, although the average power consumption acquirer  121   a  of the control device  12  divides the power consumption amount acquired from the air conditioner  11  by the set time period, and obtains the average power consumption of the air conditioner  11  in the set time period, the present disclosure is not limited to this example. 
     The average power consumption acquirer  121   a  may multiply a predetermined coefficient k by the obtained average power consumption to obtain the average power consumption (=k×average power consumption) in the set time period for each piece of identification information. The coefficient may be a positive value. 
     In the air-conditioning system  10  of Embodiment 1 and the air-conditioning system  30  of Embodiment 3 described above, although the control device  12  divides the power consumption amount of the air conditioner  11  in the set time period by the set time period, and obtains the average power consumption of the air conditioner  11  in the set time period, the present disclosure is not limited to this example 
     The control device  12 , for example, may acquire a power consumption (an instantaneous value) at multiple times from the air conditioner  11  during the set time period, obtain an average value of the acquired power consumption, and thus obtain an average power consumption of the air conditioner  11  in the set time period. 
     Also, in the air-conditioning system  20  of Embodiment 2 and the air-conditioning system  30  of Embodiment 3 described above, although the control device  12  divides the generated power amount in the set time period by the set time period, and then obtains the generated power of the photovoltaic apparatus  31  in the set time period, the present disclosure is not limited to this example 
     The control device  12 , for example, may acquire a generated power (an instantaneous value) from the photovoltaic apparatus  31  at multiple times during the set time period, then obtain an average value of values of the acquired generated power, and thus obtain a generated power of the photovoltaic apparatus  31  in the set time period. 
     Also, the air-conditioning systems  10  to  30  in the above-described embodiments include multiple air conditioners  11  but the present disclosure is not limited to this example and may include one air conditioner  11 . 
     Also, the air-conditioning systems  20  and  30  in the above-described embodiments include one photovoltaic apparatus  31  but the present disclosure is not limited to this, for example, a variation may be made to include multiple photovoltaic apparatuses  31 . 
     Also, although the air-conditioning systems  10  to  30  in the above-described embodiments include the air conditioner  11 , this is just an example, and the included electrical apparatus may be a lighting device and the like, instead of the air conditioner  11 . 
     Also, although the air-conditioning systems  10  to  30  in the above-described embodiments include one control device  12  with respect to multiple air conditioners  11 , the present disclosure is not limited to this example. The air conditioning systems  10  to  30  in the embodiments may include one control device  12  with respect to one air conditioner  11 . That is to say, the air-conditioning systems  10  to  30  in the embodiments may include multiple control devices  12  with respect to multiple air conditioners  11 . 
     Also, in the above-described air-conditioning system  10  in Embodiment 1 and the air-conditioning system  30  in Embodiment 3, the air conditioner  11  transmit to the control device  12  a wireless signal indicating a power consumption amount. Also, in the air-conditioning system  20  in Embodiment 2 and the air-conditioning system  30  in Embodiment 3, the photovoltaic apparatus  31  transmits to the control device  12  a wireless signal indicating a generated power amount. However, the present disclosure is not limited to these examples. The air conditioner  11  may transmit, by wired communication, to the control device  12  a pulse signal indicating the power consumption amount. Also, the photovoltaic apparatus  31  may transmit, by wired communication, to the control device  12 , a pulse signal indicating the generated power amount. 
     Also, although the air-conditioning systems  10  to  30  in the above-described embodiments are described as having the demand time period of, 30 minutes, for example, and the set time period of, 3 minutes, for example, the present disclosure is not limited to these examples. The demand time period may be 60 minutes and the set time period may be 10 minutes, for example Any demand time period and set time period may be selected as long as the set time period is shorter than the demand time period. 
     The air-conditioning systems  10  to  30  in the above-described embodiments may be applied to an air-conditioning system, and the like, installed within a building, for example. When one of the air-conditioning systems  10  to  30  is applied in a residence, a user may use, for example, a household appliance installed in a residence, instead of the air conditioner  11 . Also, for example, the user may realize the control device  12  with a home energy management system (HEMS) controller. 
     Also, in the above-described air-conditioning system  20  of Embodiment 2 and the air-conditioning system  30  of Embodiment 3, although the control device  12  distributes the surplus power among all the air conditioners  11 , adds the distributed surplus power to the demand initial value D that is together with each piece of identification information (each air conditioner  11 ), and updates the demand value of all the air conditioners  11 , the present disclosure is not limited to this example. The control device  12  distributes the surplus power to the air conditioners  11  belonging to a predetermined group among the air conditioners  11 . The control device  12  adds the distributed surplus power to the demand initial value D that is together with the air conditioners  11  belonging to the previously-described group. In this way, the control device  12  updates the demand value of the air conditioners  11  belonging to the predetermined group, and may maintain the demand value of the air conditioner  11  not belonging to the group at the demand initial value D. There may be one group or there may be multiple groups. 
     Also, in the above-described air-conditioning system  10  in Embodiment 1 and the air-conditioning system  20  in Embodiment 2, although the control device  12  individually (individually for each piece of identification information) updates the demand value of each air conditioner  11 , the present disclosure is not limited to this example. For example, the control device  12  obtains the spare power of all of the air conditioners  11  (obtains the total spare power). The control device  12  also distributes the obtained total power to the air conditioners  11  belonging to the predetermined group among all of the air conditioners  11 . The control device  12  also adds the distributed spare power to the demand initial value D that is together with the air conditioners  11  belonging to the previously described group. In this way, the control device  12  updates the demand value of the air conditioner  11  belonging to the predetermined group and may maintain the demand value of the air conditioner  11  not belonging to the group at the demand initial value D. 
     In the above-described embodiments, the program for controlling the controller  121  may be stored in and distributed with a non-transitory computer-readable recording medium such as a flexible disk, a compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), a magneto-optical disc (MO) and/or the like, and the controller  121  that executes the process illustrated in  FIGS. 4, 7, and 10  may be comprised by installing that program on a computer and/or the like. 
     Also, the above-described program may be stored on a disk device, and/or the like of a predetermined server device on a communication network such as the Internet and/or the like, and superimposed on carrier waves and downloaded and/or the like, for example 
     In addition, when the process illustrated in the above-described  FIG. 4, 7 , or  10  are realized by being partitioned by each operating system (OS), or are realized through cooperation between OS and applications, the parts other than the OS may be stored on the medium and distributed, and may be downloaded and/or the like. 
     The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled.