EP2333445A1

EP2333445A1 - Air-conditioning and refrigerating system

Info

Publication number: EP2333445A1
Application number: EP09815892A
Authority: EP
Inventors: Tsuyoshi Kawaai
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2008-09-29
Filing date: 2009-09-25
Publication date: 2011-06-15
Also published as: US20110167852A1; CN101915481A; WO2010035470A1; JP2010078272A; JP5405076B2; EP2333445A4; CN101915481B

Abstract

An air-conditioning refrigerating system that enables demand control based on operation control of an air-conditioning system and a refrigerating system is provided. The air-conditioning refrigerating system 1 is constructed to have an air-conditioning system 10 in which plural indoor units 34 are connected to an outdoor unit 32 to air-condition a building, a refrigerating system 12 in which plural low-temperature showcases 7 are connected to a rack system refrigerating machine 3 to cool each of the low-temperature showcases 7, a main controller 4 for generating and outputting air-conditioning demand data for varying power consumption of the refrigerating system and refrigerating demand data for varying power consumption of the refrigerating system 12 on the basis of commercial power consumption of the building, and an external controller 14 that is provided separately from the refrigerating system 12, receives the refrigerating demand data from the main controller 4 and controls the operation of the rack system refrigerating machine on the basis of the refrigerating demand data.

Description

The present invention relates to a technique for performing demand control on the basis of commercial power consumed in facilities such as a store or the like.

background Art

There has been known a refrigerating system in which plural low-temperature showcases such as freezing/chilling showcases or the like are connected to a refrigerating machine in parallel through refrigerant pipes. Plural low-temperature cases as described above are installed in a store such as a supermarket or the like, and provided to display and sell foods while freezing or chilling the foods. Furthermore, an air conditioning system for performing an air-conditioning operation on the inside of the store. In such a store, so-called demand control is performed to integrate consumed commercial power every predetermined time and reduce the commercial power consumption so that the integration value does not exceed a predetermined value or more. In general, the reduction of the commercial power consumption has been implemented to stop the operation of the air-conditioning system (for example, see Patent Document 1).
Furthermore, in a refrigerating system, a low-pressure side pressure sensor for detecting refrigerant pressure of a low-pressure side of a refrigerating machine is provided, and a microcomputer contained in the refrigerating machine controls a compressor so that the low-pressure side pressure is kept to a predetermined set value, thereby enhancing energy saving performance (for example, see Patent Document 2).

Prior Art Document

Patent Document

Patent Document 1: JP-A-2000-186844
Patent Document 2: JP-A-62-116862

Summary of the Invention

Problem to be solved by the Invention

It would be expected to further reduce the commercial power consumption by controlling the operation of the refrigerating system in addition to the air-conditioning system under demand control.
However, the microcomputer contained in the refrigerating machine controls the operation on the basis of a program which is optimized to the construction of the refrigerating machine, and thus it has been difficult to give the control device concerned with an instruction of controlling power consumption from the external.
The present invention has been implemented in view of the foregoing situation, and has an object to provide an air-conditioning refrigerating system that enables demand control based on operation control of an air-conditioning system and a refrigerating system.

Means of solving the Problem

In order to attain the above object, there is provided an air-conditioning system in which plural indoor units are connected to an outdoor unit to air-condition a building, characterized by comprising: a refrigerating system in which a plurality of low-temperature showcases are connected to a refrigerating machine to cool each of the low-temperature showcases; a main control device for generating and outputting air-conditioning demand data for varying power consumption of the air-conditioning system and refrigerating demand data for varying power consumption of the refrigerating system on the basis of commercial power consumption; and an external control device that is provided separately from the refrigerating system, receives the refrigerating demand data from the main control device and controls an operation of the refrigerating machine on the basis of the refrigerating demand data.
Furthermore, according to the present invention, in the above air-conditioning refrigerating system, the external control device that is configured to acquire control setting required for control of a main element for determining cooling capacity of the refrigerating machine, and controls the main element of the refrigerating machine on the basis of an operation state of the refrigerating machine.
According to the present invention, in the air-conditioning refrigerating system, the external control device is configured to acquire, as the control setting, compressor control setting required for capacity control of a compressor installed in the refrigerating machine, and controls a capacity of the compressor on the basis of low-pressure side pressure of the refrigerating machine.
According to the present invention, in the above air-conditioning refrigerating system, the external control device is configured to acquire, as the control setting, condenser control setting required for condensation capacity control of a condenser installed in the refrigerating machine, and controls a condensation capacity of the condenser on the basis of a high-pressure side pressure of the refrigerating machine.
According to the present invention, in the above air-conditioning refrigerating system, the main control device controls the air-conditioning system in priority to the refrigerating system on the basis of power consumption.
According to the present invention, in the above air-conditioning refrigerating system, when the power consumption of the refrigerating system is controlled to be varied, the main control device controls the condensation capacity of the condenser in priority to the capacity of the compressor.
According to the present invention, in the above air-conditioning refrigerating system, the refrigerating machine is a refrigerating machine that is freely constructed by selecting main elements for determining a cooling capacity from some types.

Effect of the Invention

According to the present invention, there is provided the external control device that is provided separately from the refrigerating system, receives the refrigerating demand data from the main control device and controls the operation of the refrigerating machine on the basis of the refrigerating demand data. Therefore, the control of varying the power consumption can be performed from the external main control device through the external control device. Accordingly, the demand control having a high power consumption reducing effect can be performed.

Brief Description of the Drawings

[Fig. 1] Fig. 1 is a diagram showing the construction of an air-conditioning refrigerating system according to an embodiment of the present invention.
[Fig. 2] Fig. 2 is a block diagram showing the functional construction of a main controller.
[Fig. 3] Fig. 3 is a diagram showing an example of demand control setting.
[ Fig. 4] Fig. 4 is a diagram showing an example of capacity control setting.
[Fig. 5] Fig. 5 is a diagram showing an example of condensation capacity control setting.
[Fig. 6] Fig. 6 is a block diagram showing the functional construction of a compressor controller.
[Fig. 7] Fig. 7 is a block diagram showing the functional construction of the condenser controller.
[Fig. 8] Fig. 8 is a flowchart showing demand control based on a main controller.
[Fig. 9] Fig. 9 is a flowchart showing capacity control based on the compressor controller.
[Fig. 10] Fig. 10 is a flowchart showing condensation capacity control based on the condenser controller.

Best mode for carrying out the Invention

An embodiment according to the present invention will be described hereunder with reference to the drawings.
Fig. 1 is a diagram showing the construction of an air-conditioning system 1 according to an embodiment.
As shown in Fig. 1, an air-conditioning refrigerating system 1 has an air-conditioning system 10, refrigerating system 12, a main controller (main control device) 4 and an external controller (external control device) 14, and the air-conditioning system 10 and the external controller 14 are connected to the main controller 4 through a communication line 24. The air-conditioning refrigerating system 1 is provided with a power meter 29 for measuring the consumption commercial power of a building in which the air-conditioning system 10 and the refrigerating system 12 are laid, and a measurement value thereof is input to the main controller 4.
The air-conditioning system 10 is constructed by connecting plural indoor units 34 to outdoor units 32 through refrigerant pipes 36, and performs air-conditioning operation of a building by each indoor unit 34. The description will be made on the assumption that the air-conditioning system 10 is provided with two air-conditioning systems including mutually independent refrigerant circuits each of which comprises an outdoor unit 32 and indoor units 34. However, the number of systems may be arbitrary, and the numbers of the outdoor units 32 and the indoor units 34 in each air-conditioning system may be arbitrary.
The refrigerating system 12 has a refrigerating circuit in which plural low-temperature showcases 7 are connected to a rack system refrigerating machine 3 in parallel through a refrigerant pipe 5a as a liquid pipe and a refrigerant pipe 5b as a gas pipe.
The rack system refrigerating machine 3 has plural compressors (compressors) 9, a condenser (condenser) 11, plural condenser fans (fans for condensers) 13, a low-pressure side pressure sensor 26 for detecting the refrigerant pressure at the low-pressure side (hereinafter referred to as "low-pressure side pressure), and a high-pressure side pressure sensor 28 for detecting refrigerant pressure of the high-pressure side (hereinafter referred to as "high-pressure side pressure").
Each of the compressors 9 is a capacity fixed type compressor, and the total capacity, that is, the cooling capacity is varied on the basis of the number of operating compressors 9. Furthermore, the condenser 11 is a condenser which can be variably controlled on the basis of the number of operating condenser fans 13. In the following description, the number of compressors 9 is set to two while the number of condensers 13 is set to six, however, these numbers are not limited to these values.
Each of the low-temperature showcase 7 has an expansion valve (pressure reducing device) 15, and a cooling unit 17, and a liquid electromagnetic valve 19 is connected to the inlet of the expansion valve 15.
The liquid electromagnetic valve 19 is a valve for controlling supply of refrigerant to the expansion valve 15, and the in-case temperature of the low-temperature showcase 7 based on the cooling operation of the cooling unit 17 is controlled by opening/closing the liquid electromagnetic valve 19.
That is, the low-temperature showcase 7 has an in-case temperature sensor 21 for detecting the in-case temperature of the inside of the showcase and a microcomputer 23. The microcomputer 23 stores an upper limit temperature and a lower limit temperature which are set at the upper and lower sides of an in-case set temperature, and executes ON-OFF control of opening the liquid electromagnetic valve 19 at the upper limit temperature and closing the liquid electromagnetic valve 19 at the lower limit temperature. Through the ON-OFF control concerned, the in-case temperature of the low-temperature showcase 7 is averaged and made to approach to the in-case set temperature. Not only the low-temperature showcases 7, but also other load facilities such as a chilling/freezing prefabricated storage, etc. may be connected to the rack system refrigerating machine 3.
The rack system refrigerating machine 3 is freely constructed by freely selecting the compressors 9, the condensers 1 and the condenser fans 13 as main elements for determining the cooling capacity from some types on the basis of the maximum cooling capacity required for the refrigerating system 12 and combining the selected main elements.
More specifically, the maximum cooling capacity required at the installation place of the refrigerating system 12 is determined on the basis of the number of low-temperature showcases 7, the in-case set temperature, the in-store temperature and an environmental condition such as the outside air temperature, etc., and a refrigerating machine which has an extra cooling capacity with respect to the thus-determined maximum cooling capacity is selected when the refrigerating system 12 is installed. At this time, the maximum cooling capacity of the refrigerating machine is determined when it is manufactured. Therefore, when a maker or the like does not prepare any refrigerating machine having the proper maximum cooling capacity which meets the environmental condition when the refrigerating machine is installed, a refrigerating machine which has a further extra cooling capacity with respect to the maximum cooling capacity must be installed, and thus vainness occurs in the cooling capacity.
On the other hand, according to the rack system refrigerating machine 3 of this embodiment, the capacities of the compressors and the condensation capacities of the condensers as the main elements for determining the cooling capacity are freely selected from products of the same maker or other makers by a user in conformity with the maximum cooling capacity (thermal load) required under the environmental condition when the rack system refrigerating machine is installed, and the user combines these main elements by himself/herself to freely construct the refrigerating machine. Therefore, a refrigerating machine having the optimum maximum cooling capacity can be constructed.
Furthermore, in the rack system refrigerating machine 3, the main elements are combined with one another in conformity with the required maximum cooling capacity, and thus a cooling system having no needless cooling capacity and a high energy saving effect can be implemented as compared with a conventional packaged refrigerating machine.
In addition, according to the rack system refrigerating machine 3, it is unnecessary to package constituent parts in one housing, and thus such a layout that heat retention can be prevented even when the condensers 11 and the condenser fans 13 are disposed outdoors while the compressors 9 are disposed indoors. Furthermore, the installation space is not restricted by the housing, and the degree of freedom to determine the types of the condensers 11 and the condenser fans 13 and the number of the condensers 13 can be enhanced.
In the rack system refrigerating machine 3 as described above, the types and numbers of the compressors 9, the condensers 11 and the condenser fans 13 are unstable, and thus it is difficult that the refrigerating machine is constructed so as to contain a microcomputer and the capacities of the compressors 9 and the condensation capacities of the condensers 11 are controlled by the microcomputer as in the case of a conventional refrigerating machine. Therefore, according to the air-conditioning refrigerating system 1 of this embodiment, the external controller 14 which controls the main elements of the rack system refrigerating machine 3 to vary the cooling capacity is provided separately from the rack system refrigerating machine 3.
The external controller 14 has a compressor controller 6 for controlling the capacities of the plural compressors 9 provided to the rack system refrigerating machine 3, and a condenser controller 8 for controlling the condensation capacities of the condensers 11.
The compressor controller 6 turns on/off each of plural compressors 9 on the basis of refrigerating demand data described later from the main controller 4 to vary power consumption, and the condenser controller 8 turns on/off each of plural condenser fans 13 on the basis of the refrigerating demand data to vary power consumption.
The main controller 4 performs so-called demand control of integrating commercial power consumption used in a building every demand time period (for example, 30 minutes) and reducing the commercial power consumption so that the integration value does not exceed a predetermined value or more. The functional construction of the main controller 4 will be described hereunder with reference to Fig. 2.
Fig. 2 is a block diagram showing the functional construction of the main controller 4.
In Fig. 2, the control unit 40 centrally controls each part of the main controller 4. Demand control setting and refrigerating machine control setting are input to the control setting input unit 41. The demand control setting is setting information required for the demand control of the air-conditioning refrigerating system 1, and an example thereof is shown in Fig. 3.
Fig. 3 is a diagram showing an example of the demand control setting.
With respect to the demand control, plural determination timings are provided during the demand time period, and in order to prevent the integration value from exceeding a predetermined value at the end time of the demand time period, it is determined on the basis of the integration value of the commercial power consumption at each determination timing whether the power consumption is reduced or not. With respect to the demand control setting, integration values Wa to Wd of commercial power consumption as threshold values for determining every determination timing Ta to Td whether the power consumption is reduced or not, and equipment to be stopped to reduce the power consumption are defined in association with one another as settings required for the demand control.
In this demand control setting, the air-conditioning system 10 is stopped in priority to the refrigerating system 12 when the power consumption is reduced. In a case where it is still necessary to reduce the power consumption even when all the air-conditioning systems of the air-conditioning system 10 are stopped, only one of the condenser fans 13 is stopped to reduce the condensation capacity to the extent that the condensation capacity is not nullified. Even in this case, where it is necessary to further reduce the power consumption, only one of the compressors 9 is stopped to reduce the capacity thereof to the extent that the capacity is not nullified, whereby the power consumption is reduced with keeping the cooling capacity of the rack system refrigerating machine 3 as much as possible.
The refrigerating machine control setting represents a setting required to control the main elements for determining the cooling capacity so that' s the cooling capacity of the rack system refrigerating machine 3 is varied.
More specifically, according to this embodiment, the capacity of the compressors 9 is controlled on the basis of the refrigerant pressure of the low-pressure side of the rack system refrigerating machine 3 (hereinafter referred to as "low-pressure side pressure"), and the condensation capacity of the condensers 11 is controlled on the basis of the refrigerant pressure of the high-pressure side (hereinafter referred to as "high-pressure side pressure"). Through this control, the rack system refrigerating machine 3 can be operated with the compressor capacity and condensation capacity necessary and sufficient to keep a predetermined cooling capacity under operation of the rack system refrigerating machine 3, and the energy saving of the rack system refrigerating machine 3 can be performed.
However, as described above, in the rack system refrigerating machine 3, the types of numbers of the compressors 9, the condensers 11 and the condenser fans 13 are determined when they are installed, and thus it is impossible to preinstall a program for controlling the compressors 9 and the condenser fans 13 into the external controller 14. Therefore, according to this embodiment, the compressor control setting required for the capacity control of the compressors 9 and the condenser control setting required for the condensation capacity control of the condensers 11 are input to the main controller 4, and output from the main controller 4 to the external controller 14.
Fig. 4 is a diagram showing an example of the compressor control setting.
As shown in Fig. 4, the association relationship between the turn-on/off of each compressor 9 and the total output is defined in the compressor control setting, and steps No. 1, step No. 2, ... are allocated to combinations of the turn-on/off of the respective compressors 9 in the order of increasing the total output. That is, when the total output is reduced to lower the cooling capacity in the capacity control, step No. smaller than the step No. corresponding to the combination of turn-on/off of the respective compressors 9 at that time is selected, and the total output can be reduced by turning on/off each compressor 9 according to the combination defined by the selected step No. Conversely, when the total output is increased to increase the cooling capacity, larger step No. is selected, and each compressor 9 is turned on/off according to the combination defined by the selected step No., whereby the total output can be increased.
Here, the rack system refrigerating machine 3 according to this embodiment is provided with two capacity fixed type compressors 9 which are different in capacity, and thus four combinations of on/off state are obtained as shown in the figure. At this time, when the compressors 9 have the same capacity, combinations having the same total output occur in the four combinations, and thus the number of the combinations having different total outputs is reduced. However, by using compressors 9 having different capacities, the number of combinations having different total outputs is maximized, and the total output of the compressors 9 can be minutely controlled.
Fig. 5 is a diagram showing an example of the condenser control setting.
As shown in Fig. 5, in the condenser control setting, the high-pressure side pressure for cut-in/cut-out is defined in each of the condenser fans 13, and the condenser fan 13 is regulated to be cut in as the high-pressure side pressure increases. The cut-in/cut-off high-pressure side pressure is provided with a hysteresis for preventing chattering. In the condensation capacity control, the high-pressure side pressure of the rack system refrigerating machine 3 is monitored, a condenser fan 13 which reaches the cut-in pressure due to variation of the high-pressure side pressure is turned on, and a condenser fan 13 which reaches the cut-out pressure is turned off. Accordingly, only condenser fans 13 which meet the condensation capacity required to the rack system refrigerating machine 3 are operated, so that the power consumption can be reduced as compared with a case where all the condenser fans 13 are driven.
A measurement value of the commercial power consumption of the building is input to a power measurement value input unit 42 of Fig. 2. The control unit 40 calculates the integration value of the commercial power consumption for the demand time period on the basis of the measurement value concerned, and generates air-conditioning demand data for specifying an air-conditioning system to be stopped (turned off) and refrigerating demand data for specifying main elements of the rack system refrigerating machine 3 to be stopped (turned off) on the basis of the integration value concerned and the demand control setting.
An air-conditioning communicating unit 43 transmits the air-conditioning demand data to the air-conditioning system 10, whereby the specified air-conditioning system is stopped and the power consumption of the air-conditioning system 10 is reduced in the air-conditioning system 10.
A compressor control communicating unit 44 transmits data specifying compressors 9 as equipment to be stopped out of the refrigerating demand data, and transmits data specifying condenser fans 13 as equipment to be stopped out of the refrigerating demand data. Accordingly, the specified main elements are stopped and the power consumption is reduced in the rack system refrigerating machine 3.
Furthermore, the compressor control setting is transmitted from the compressor controller communicating unit 44 to the compressor controller 6, and the condenser control setting is transmitted from the condenser controller communicating unit 45 to the condenser controller 8. In the compressor controller 6, the capacity control based on the compressor control setting is executed, and in the condenser controller 8, the condensation capacity control based on the condenser control setting is executed.
Fig. 6 is a block diagram showing the functional construction of the compressor controller 6.
In Fig. 6, the control unit 60 centrally controls each part of the compressor controller 6, and also generates a compressor control signal for controlling turn-on/off of each of the compressors 9 installed in the rack system refrigerating machine 3. The control unit 60 comprises a microcomputer, for example. A controller communicating unit 61 communicates with the main controller 4 through the communication line 24, and receives the compressor control setting and the refrigerating demand data. A control setting storage unit 62 stores the compressor control setting. The detection value of the low-pressure side pressure is input from the low-pressure side pressure sensor 26 provided to the rack system refrigerating machine 3 to a low-pressure side pressure sensor input unit 63. The control unit 60 compares the detection value of the low-pressure side pressure with the low-pressure side pressure set value, and changes the capacity of the rack system refrigerating machine 3 according to the compressor control setting.
Specifically, when the low-pressure side pressure is lower than the low-pressure side pressure set value, it indicates that a needless cooling capacity occurs and thus the energy saving performance is degraded. Conversely, when the low-pressure side pressure is higher than the low-pressure side pressure set value, it indicates that the cooling capacity lacks ad thus the cooling performance of the low-temperature showcase 7 is damaged. Accordingly, when the low-pressure side pressure is higher than the low-pressure side pressure set value, the control unit 60 increments the step NO. of the capacity control rule one by one to increase the total output and thus enhance the cooling capacity. Conversely, when the low-pressure side pressure is lower than the low-pressure side pressure set value, the control unit 60 decrements the step No. one by one to gradually reduce the total output and thus lower the cooling capacity.
Then, the control unit 60 generates a control signal to actuate only compressors 9 whose combination is indicated by the step No. concerned.
Furthermore, when the compressors 9 are instructed to stop on the basis of the refrigerating demand data, the control unit 60 generates a control signal for stopping one of the compressors 9 being operated.
A compressor control signal output unit 64 outputs the compressor control signal to the compressors 9 of the rack system refrigerating machine 3.
Fig. 7 is a block diagram showing the functional construction of the condenser controller 8.
In Fig. 7, the control unit 80 centrally controls each part of the condenser controller 8 , and also generates a condenser fan control signal for controlling turn-on/off of each of the condenser fans 13 installed in the rack system refrigerating machine 3. For example, the control unit 80 comprises a microcomputer.
A controller communicating unit 81 communicates with the main controller 4 through the communication line 24, and receives the condenser control setting and the refrigerating demand data. A control setting storing unit 82 stores the control setting. The detection value of the high-pressure side pressure is input from the high-pressure side pressure sensor 28 provided to the rack system refrigerating machine 3 to a high-pressure side pressure sensor input unit 83.
The control unit 80 generates the condenser fan control signal for turning on/off the condenser fans 13 according to the detection value of the high-pressure side pressure and the condenser control setting.
Furthermore, when it is instructed to stop the condenser fan 13 on the basis of the refrigerating demand data, the control unit 80 generates a control signal for stopping one of the condenser fans 13 being operated.
A condenser fan control signal output unit 84 outputs this condenser fan control signal to each condenser fan 13 of the rack system refrigerating machine 3.
Next, the operation of the thus-constructed air-conditioning refrigerating system 1 will be described.
As described above, in the air-conditioning refrigerating system 1, the demand control is executed by the main controller 4 as described above, and also the capacity control of the compressors 9 is executed by the compressor controller 6 and the condensation capacity control of the condensers 11 is executed by the condenser controller 8 in the refrigerating system 12.
Fig. 8 is a flowchart showing the demand control of the main controller 4.
At the initial stage that the air-conditioning refrigerating system is installed, the demand control setting based on the construction of the rack system refrigerating machine 3 is input to the main controller 4 by a service man or the like (step S1) . Subsequently, the main controller 4 resets the demand time period to "0 minute" and then starts the time count of the lapse time (step S2). Thereafter, when the determining timing of the demand control described above comes (step S3: YES), the main controller 4 calculates the integration value of the commercial power consumed till the determination timing concerned (step S4), and determines on the basis of the demand control setting whether the integration value exceeds a threshold value (step S5). When the integration value exceeds the threshold value (step S5: YES), the main controller 4 generates and outputs air-conditioning demand data or/and refrigerating demand data on the basis of the demand control setting to reduce the power consumption (step S6). Accordingly, the air-conditioning system, the compressor 9 or the condenser fan 13 is stopped to reduce the power consumption.
Subsequently, the main controller 4 determines whether the demand time period is finished or not (for example, 30 minutes elapses or not) (step S7). When the demand time period is not finished (step S7: NO), the main controller 4 returns the processing procedure to the step S3 to perform the determination at the next determination timing. When the demand time period is finished (step S7: YES), there is no problem even if each equipment which has been stopped within this demand time period because of reduction of the power consumption is started, and thus the main controller 4 generates and outputs data for starting these equipment (step S8). The main controller 4 returns the processing procedure to the step S2 to perform the demand control for the next demand time period.
Fig. 9 is a flowchart showing the capacity control of the compressor controller 6.
As shown in Fig. 9, the compressor controller 6 acquires low-pressure side pressure from the low-pressure side pressure sensor 26 of the rack system refrigerating machine 3 every fixed time (step S10), and compares the acquired low-pressure side pressure with the low-pressure side pressure set value (step S11) . When the low-side pressure exceeds the low-pressure side pressure set value and the cooling capacity of the rack system refrigerating machine 3 lacks (step S11: YES), in order to increase the cooling capacity and keep the cooling performance of the low-temperature showcase 7, the step No. of the condenser control setting is incremented by "1" (step S12), and the compressor control signal based on the condenser control setting is generated and output to the compressor 9 (step S13).
Furthermore, when the low-pressure side pressure falls below the low-pressure side pressure set value and thus a surplus cooling capacity occurs in the rack system refrigerating machine 3 (step S11: NO), in order to lower the cooling capacity and reduce the power consumption of the rack system refrigerating machine 3, the step No. of the condenser control setting is decremented by "1" (step S14), and the compressor control signal based on the condenser control setting is generated and output to the compressors 9 (step S13).
When it is determined whether the low-pressure side pressure exceeds the low-pressure side pressure set value, the low-pressure side pressure set value as a determination criterion is provided with a hysteresis. That is, when the low-pressure side pressure exceeds a pressure which is higher than the low-pressure side pressure set value by only a predetermined value, "exceeding" is determined. When the low-pressure side pressure falls below a pressure which is lower than the low-pressure side pressure set value by only a predetermined value, "falling below" is determined. The predetermined values may be transmitted from the main controller 4 to the compressor controller 6 together with the low-pressure side pressure set value, or preinstalled in a program of the compressor controller 6 together with the low-pressure side pressure set value.
Subsequently, the compressor controller 6 determines whether the refrigerating demand data is received (step S15). When no refrigerating demand data is received (step S15: NO), the compressor controller 6 returns the processing procedure to the step S1. When the refrigerating demand data is received (step S15: YES), the compressor controller 6 outputs a compressor control signal for stopping one of the compressors 9 under operation (step S16) . Accordingly, through the demand control, the compressor 9 is stopped and the power consumption is reduced.
Fig. 10 is a flowchart showing the condensation capacity control of the condenser controller 8.
As shown in Fig. 10, the condenser controller 8 acquires high-pressure side pressure from the high-pressure side pressure sensor 28 of the rack system refrigerating machine 3 every fixed time (step S20). The condenser controller 8 determines on the basis of this high-pressure side pressure and the condenser control setting whether there is any condenser fan 13 to be turned on/off to vary the condensation capacity (step S21) . When there is any condensation fan 13, the condenser controller 8 generates the condenser control signal for turning on/off the condenser fan 13 concerned, and outputs the condenser control signal to the condenser fan 13 (step S22).
Subsequently, the condenser controller 8 determines whether any refrigerating demand data is received (step S23). When no refrigerating demand data is received (step S23: NO), the condenser controller 8 directly returns the processing procedure to the step S1. When refrigerating demand data is received (step S23: YES), the condenser controller 8 generates and outputs a condenser fan control signal for stopping one of the condenser fans 13 being operated (step s24). Accordingly, through the demand control, the condenser fan 13 is stopped and the power consumption is reduced.
As described above, according to this embodiment, there is provided the external controller 14 which is provided separately from the refrigerating system 12, receives the refrigerating demand data from the main controller 4 and controls the operation of the rack system refrigerating machine 3 on the basis of the refrigerating demand data. Therefore, the control for varying the power consumption can be performed from the external main controller 4 through the external controller 14. Accordingly, the demand control having a higher power consumption reducing effect can be performed as compared with the prior art in which only the air-conditioning system 10 is subjected to the demand control.
Furthermore, according to this embodiment, the external controller 14 acquires the control setting required for the capacity control of the compressors 9 and the condensation capacity control of the condensers 11, and controls to vary the cooling capacity on the basis of the operation state (the low-pressure side pressure and the high-pressure side pressure) of the rack system refrigerating machine 3. Therefore, the energy saving performance of the rack system refrigerating machine 3 can be more enhanced.
Particularly, the rack system refrigerating machine 3 is constructed by selecting the compressors 9 and the condensers 11 for arbitrarily determining the cooling capacity from some types thereof and freely installing the selected compressors 9 and condensers 11. Therefore, the optimum refrigerating machine in which no needless cooling capacity occurs with respect to the required cooling capacity can be constructed. In addition, in the rack system refrigerating machine 3 described above, it is difficult to control the cooling capacity of a built-in microcomputer. However, according to this embodiment, the external controller 14 is provided and thus the cooling capacity control can be implemented.
Furthermore, the above-described embodiment is merely an example of the present invention, and it may be arbitrarily modified and applicable within the scope of the present invention. Description of Reference Numerals

1 air-conditioning refrigerating system
2 refrigerating circuit
3 rack system refrigerating machine (refrigerating machine)
4 main controller (main control device)
6 compressor controller
7 low-temperature showcase
8 condenser controller
9 compressor
10 air-conditioning system
11 condenser
12 refrigerating system
13 condenser fan
14 external controller (external control device)
26 low-pressure side pressure sensor
28 high-pressure side pressure sensor
29 power meter
32 outdoor unit
34 indoor unit

Claims

An air-conditioning system in which plural indoor units are connected to an outdoor unit to air-condition a building, characterized by comprising:
a refrigerating system in which a plurality of low-temperature showcases are connected to a refrigerating machine to cool each of the low-temperature showcases;

a main control device for generating and outputting air-conditioning demand data for varying power consumption of the air-conditioning system and refrigerating demand data for varying power consumption of the refrigerating system on the basis of commercial power consumption; and

an external control device that is provided separately from the refrigerating system, receives the refrigerating demand data from the main control device and controls an operation of the refrigerating machine on the basis of the refrigerating demand data.
The air-conditioning refrigerating system according to claim 1, wherein the external control device that is configured to acquire control setting required for control of a main element for determining cooling capacity of the refrigerating machine, and controls the main element of the refrigerating machine on the basis of an operation state of the refrigerating machine.
The air-conditioning refrigerating system according to claim 2, wherein the external control device is configured to acquire, as the control setting, compressor control setting required for capacity control of a compressor installed in the refrigerating machine, and controls a capacity of the compressor on the basis of low-pressure side pressure of the refrigerating machine.
The air-conditioning refrigerating system according to claim 2 or 3, wherein the external control device is configured to acquire, as the control setting, condenser control setting required for condensation capacity control of a condenser installed in the refrigerating machine, and controls a condensation capacity of the condenser on the basis of a high-pressure side pressure of the refrigerating machine.
The air-conditioning refrigerating system according to claim 4, wherein the main control device controls the air-conditioning system in priority to the refrigerating system on the basis of power consumption.
The air-conditioning refrigerating system according to claim 4, wherein when the power consumption of the refrigerating system is controlled to be varied, the main control device controls the condensation capacity of the condenser in priority to the capacity of the compressor.
The air-conditioning refrigerating system according to any one of claim 1 to 6, wherein the refrigerating machine is a refrigerating machine that is freely constructed by selecting main elements for determining a cooling capacity from some types.