DESCRIPTION
Title of Invention
AIR CONDITIONING SYSTEM
Technical Field
[0001]
The present invention relates to an air-conditioning system that suppresses usage electric power when an emergency power supply is used. Background Art [0002]
In a typical air-conditioning system such as a variable refrigerant flow system, an outdoor unit serving as a heat source apparatus disposed outside a building is connected to a plurality of indoor units disposed inside the building, and the air-conditioning system usually performs cooling operation, heating operation, or other operation on electric power that is supplied from a commercial power supply. In such air-conditioning systems, some of the air-conditioning systems include an uninterruptible power unit or emergency generator as an emergency power supply, and operate on electric power from the emergency power supply in the event of an interruption of a commercial power supply that is a normal power supply (see, for example, Patent Literature 1). [0003]
Patent Literature 1 describes an air-conditioning system including a compressor, an indoor-unit air-sending device, a unit that detects an interruption of a commercial power supply, and a unit that suppresses the capacity, that is, one or both of the rotation frequency of the compressor and the volume of air of the indoor-unit air-sending device when an interruption of the commercial power supply is detected. The air-conditioning system of Patent Literature 1 has, for example, a power suppression operation mode in which the compressor is operated at the lowest frequency and the volume of air of the indoor-unit air-sending device is reduced, and is configured to operate in the power suppression operation mode in the event of a power failure of the commercial power supply.

Citation List Patent Literature [0004]
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2007-24431 Summary of Invention Technical Problem [0005]
However, in the air-conditioning system of Patent Literature 1, the frequency of the compressor and the volume of air of the indoor-unit air-sending device are set regardless of electric power that is supplied from an emergency power supply. For this reason, for example, when the compressor is set at the lowest frequency, the air-conditioning system is able to only exercise a minimum air-conditioning capacity although the air-conditioning system still has an available capacity to the upper limit of electric power supplied, so the capacity can be insufficient for an air conditioning load. [0006]
The present invention is made to solve the above-described inconvenience, and it is an object of the present invention to provide an air-conditioning system that performs maximum air-conditioning operation even in a state where electric power supplied is suppressed when a normal power supply fails and electric power is supplied from an emergency power supply. Solution to Problem [0007]
According to an embodiment of the present invention, an air-conditioning system includes one or a plurality of air-conditioning apparatuses configured to operate when the one or plurality of air-conditioning apparatuses receive electric power that is supplied from a normal power supply during normal times and to operate when the one or plurality of air-conditioning apparatuses receive electric power that is supplied from an emergency power supply during a power failure of the normal power supply, an operation control unit configured to control an operation of

the one or plurality of air-conditioning apparatuses, a power failure determination unit configured to detect a power failure of the normal power supply, and an operation instruction unit configured to, when a power failure is detected by the power failure determination unit, execute an electric power limited operation that limits an electric power that the one or plurality of air-conditioning apparatuses use on the basis of an upper limit electric power set in advance. The operation control unit is configured to, when the electric power limited operation is being executed by the operation instruction unit, control the operation of the one or plurality of air-conditioning apparatuses within a range in which a total usage electric power of the one or plurality of air-conditioning apparatuses is lower than or equal to the upper limit electric power. Advantageous Effects of Invention [0008]
With the air-conditioning system according to an embodiment of the present invention, during a power failure of the normal power supply, the electric power that the one or plurality of air-conditioning apparatuses use is limited on the basis of the upper limit electric power set in advance. That is, the air-conditioning system according to an embodiment of the present invention is configured in such a manner that the electric power is limited to the upper limit electric power or below, and the operation control unit is able to control the operation within the range that does not exceed the upper limit electric power. Consequently, as compared to the power suppression operation mode as in the case of the existing art, the operation efficiency during usage of the emergency power supply is improved. For example, when the upper limit electric power is an electric power that is supplied from the emergency power supply, the air-conditioning system is able to perform the operation at the maximum air-conditioning capacity within the range of the electric power supplied. Brief Description of Drawings [0009]
[Fig. 1] Fig. 1 is a circuit diagram showing a circuit configuration of an air-conditioning apparatus of an air-conditioning system according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a block diagram showing a schematic configuration of the air-conditioning system according to Embodiment 1 of the present invention.
[Fig. 3] Fig. 3 is a functional block diagram showing a functional configuration of the air-conditioning system according to Embodiment 1 of the present invention.
[Fig. 4] Fig. 4 is a flowchart showing control of the air-conditioning system according to Embodiment 1 of the present invention.
[Fig. 5] Fig. 5 is a flowchart showing control for electric power limited operation for single operation of the air-conditioning system according to Embodiment 1 of the present invention.
[Fig. 6] Fig. 6 is a flowchart showing control for defrosting operation during electric power limited operation of an air-conditioning system according to Embodiment 2 of the present invention. Description of Embodiments [0010]
Hereinafter, an air-conditioning system 100 of the present invention will be described with reference to the drawings. [0011] Embodiment 1
Fig. 1 is a circuit diagram showing a circuit configuration of an air-conditioning apparatus of the air-conditioning system according to Embodiment 1 of the present invention. An air-conditioning apparatus 1 will be described with reference to Fig. 1. The air-conditioning apparatus 1 is used as, for example, an air-conditioning device that heats or cools target space. The air-conditioning apparatus 1 usually operates on electric power that is supplied from a normal power supply, such as a commercial power supply, but the air-conditioning apparatus 1 is supplied with electric power from an emergency power supply in the event of an interruption of electric power that is supplied from the normal power supply. Examples of the emergency power supply include an uninterruptible power unit, an emergency generator, and other units. [0012] Configuration of Air-conditioning Apparatus 1>

The air-conditioning apparatus 1 is made up of an outdoor unit 10, two indoor units 50a and 50b, and other components. The air-conditioning apparatus 1 includes a refrigeration cycle for circulating refrigerant. The indoor units 50a and 50b are able to select a cooling operation mode or a heating operation mode as operation modes. Specifically, the air-conditioning apparatus 1 is able to switch the operation modes of the indoor units 50a and 50b to the cooling operation mode or the heating operation mode with a flow passage switching device 13 mounted in the outdoor unit 10. [0013]
The outdoor unit 10 and the indoor units 50a and 50b are connected by a refrigerant pipe 4 and a refrigerant pipe 5. Fig. 1 shows the case where the two indoor units 50a and 50b are connected in parallel with the single outdoor unit 10 as an example; however, the number of the outdoor units 10 and the number of the indoor units 50 are not specifically limited to this example. [0014]
In the following description, when the indoor unit 50a and the indoor unit 50b are not specifically distinguished from each other, each of the indoor unit 50a and the indoor unit 50b will be described as the indoor unit 50. Components mounted in each of the indoor unit 50a and the indoor unit 50b are shown with suffixes "a" and "b" added to the reference signs; however, when components are not specifically distinguished from each other, the components will be described without suffixes "a" and "b". [0015] (Outdoor Unit 10)
The outdoor unit 10 is mostly installed outdoors, and has the function of supplying cooing energy or heating energy to the indoor unit 50. The outdoor unit 10 includes a compressor 11, a check valve 12, the flow passage switching device 13, an outdoor-unit heat exchanger 14, an accumulator 16, and other components. An outdoor-unit air-sending device 15 is mounted in the outdoor unit 10. [0016]

The compressor 11 compresses refrigerant flowing in through the accumulator 16, and discharges high-temperature, high-pressure gas refrigerant. The compressor 11 may be, for example, a rotary compressor, a scroll compressor, a screw compressor, a reciprocating compressor, or another compressor. The compressor 11 should be an inverter compressor whose displacement is controllable. [0017]
The check valve 12 is provided to a discharge port of the compressor 11, and permits the flow of refrigerant only in one direction. [0018]
The flow passage switching device 13 is provided to the discharge port of the compressor 11 with the check valve 12 interposed, and switches the flows of refrigerant between the cooling operation mode and the heating operation mode. The flow passage switching device 13 may be made up of, for example, a combination of two-way valves or three-way valves, a four-way valve, or other valves. During cooling operation, the flow passage switching device 13 connects the discharge port of the compressor 11 and the outdoor-unit heat exchanger 14, with the result that refrigerant discharged from the compressor 11 is delivered to the outdoor-unit heat exchanger 14. On the other hand, during heating operation, the flow passage switching device 13 connects the discharge port of the compressor 11 and the refrigerant pipe 4, with the result that refrigerant discharged from the compressor 11 is delivered to the indoor unit 50 via the refrigerant pipe 4. When the air-conditioning apparatus 1 is a cooling-only air conditioner or a heating-only air conditioner, the flow passage switching device 13 does not need to be provided. [0019]
The outdoor-unit heat exchanger 14 serves as an evaporator during heating operation, and serves as a condenser during cooling operation. The outdoor-unit heat exchanger 14 exchanges heat between refrigerant and heat exchanging fluid, such as air that is supplied from a fluid transfer device, such as the outdoor-unit air-sending device 15. The outdoor-unit heat exchanger 14 may be, for example, a fin-and-tube heat exchanger, a microchannel heat exchanger, a shell-and-tube heat

exchanger, a heat pipe heat exchanger, a double-pipe heat exchanger, a plate heat exchanger, or another heat exchanger. In Embodiment 1, description will be made in the case where the outdoor-unit heat exchanger 14 is a fin-and-tube heat exchanger as an example. [0020]
The outdoor-unit air-sending device 15 is one example of the fluid transfer device, and supplies air to the outdoor-unit heat exchanger 14. The outdoor-unit air-sending device 15 may be, for example, a propeller fan having a plurality of blades. The outdoor-unit air-sending device 15 may be disposed at any place as long as the outdoor-unit air-sending device 15 is able to supply air to the outdoor-unit heat exchanger 14. A fluid transfer device suitable for the type of the outdoor-unit heat exchanger 14 should be selected. For example, when heat exchanging fluid is water or brine, for example, a pump is only required to be mounted in the air-conditioning apparatus 1 in place of the outdoor-unit air-sending device 15. [0021]
The accumulator 16 is provided to a suction port of the compressor 11, and accumulates excess refrigerant due to the difference between heating operation and cooling operation, excess refrigerant resulting from a transient change in operation, or excess refrigerant that is caused depending on a load condition. A transient change in operation means, for example, the case where the number of the indoor units 50 in operation is changed. The accumulator 16 separates liquid refrigerant and gas refrigerant from each other, and supplies only gas refrigerant to the compressor 11. [0022]
A controller 70 is further mounted in the outdoor unit 10. The controller 70 integrally controls the air-conditioning apparatus 1. Actuators (driving components) are connected to the controller 70. The controller 70 controls the operation of the actuators. The actuators include, for example, the compressor 11, the flow passage switching device 13, the outdoor-unit air-sending device 15, expansion devices 52 described later, indoor-unit air-sending devices 53 described later, and other components. The controller 70 is configured to detect a power failure of the normal

power supply and transmit a detection signal to a centralized controller 80 described later (see Fig. 2) or another device that is able to communicate with the controller 70. [0023]
The controller 70 controls the operation of the actuators on the basis of values detected by various sensors (not shown) (hereinafter, referred to as a sensor group 60). The sensor group 60 includes, for example, a pressure sensor, a temperature sensor, and other sensors. The pressure sensor is provided to the discharge port of the compressor 11, and measures the pressure of refrigerant that is discharged from the compressor 11. The temperature sensor is placed in each indoor unit 50, and measures the temperature. The controller 70 may be hardware such as a circuit device or may be a microcomputer, for example. [0024]
Fig. 1 shows the case where the controller 70 is mounted in the outdoor unit 10 as an example; however, the place where the controller 70 is mounted is not specifically limited. Furthermore, the indoor unit 50 may also include a controller, and the controller of the indoor unit 50 and the controller 70 may be communicably connected to each other. In this case, an instruction from a remote control or another device (not shown) is input to the controller 70 through the controller of the indoor unit 50. [0025] (Indoor Unit 50)
The indoor unit 50 is, for example, installed indoors or in other places, and has the function of cooling or heating air-conditioned space with cooling energy or heating energy that is supplied from the outdoor unit 10. Each indoor unit 50 includes an indoor-unit heat exchanger 51, the expansion device 52, the indoor-unit air-sending device 53, and other components. [0026]
The indoor-unit heat exchanger 51 serves as a condenser during heating operation, and serves as an evaporator during cooling operation. The indoor-unit heat exchanger 51 exchanges heat between refrigerant and heat exchanging fluid,

such as air that is supplied from the fluid transfer device, such as the indoor-unit air-sending device 53, and generates heating air or cooling air that is supplied to air-conditioned space. The indoor-unit heat exchanger 51 may be, for example, a fin-and-tube heat exchanger, a microchannel heat exchanger, a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-pipe heat exchanger, a plate heat exchanger, or another heat exchanger. In Embodiment 1, the case where the indoor-unit heat exchanger 51 is a fin-and-tube heat exchanger will be described as an example. [0027]
The indoor-unit air-sending device 53 is one example of the fluid transfer device, and supplies air to the indoor-unit heat exchanger 51. The indoor-unit air-sending device 53 may be, for example, a propeller fan having a plurality of blades. The indoor-unit air-sending device 53 may be disposed at any place as long as the indoor-unit air-sending device 53 is able to supply air to the indoor-unit heat exchanger 51. A fluid transfer device should be selected for the type of the indoor-unit heat exchanger 51. For example, when heat exchanging fluid is water or brine, a pump is mounted in the indoor unit 50 in place of the indoor-unit air-sending device 53 as the fluid transfer device. [0028]
The expansion device 52 reduces the pressure of refrigerant passing through the indoor-unit heat exchanger 51 or the outdoor-unit heat exchanger 14 by expanding the refrigerant. In Fig. 1, the expansion device 52 is provided between the outdoor-unit heat exchanger 14 and each indoor-unit heat exchanger 51. The expansion device 52 should be, for example, an electric expansion valve or another device that is able to adjust the flow rate of refrigerant. Instead of employing an electric expansion valve, a mechanical expansion valve that employs a diaphragm for a pressure receiving portion, a capillary tube, or another device, may be employed as the expansion device 52. [0029]

Next, the operation mode in which the air-conditioning apparatus 1 operates will be described together with the flow of refrigerant. The air-conditioning apparatus
I is configured to be able to perform cooling operation or heating operation of each
indoor unit 50 on the basis of, for example, an instruction from the indoor unit 50. In
Embodiment 1, the air-conditioning apparatus 1 is able to perform the same one of
the cooling operation and heating operation of all the connected indoor units 50a and
50b.
[0030]
(Cooling Operation Mode)
First, the cooling operation mode in which the air-conditioning apparatus 1 operates will be described. In Fig. 1, the flows of refrigerant in the cooling operation mode are represented by dashed arrows. Hereinafter, the cooling operation mode of the air-conditioning apparatus 1 will be described in the case where heat exchanging fluid is air and heat exchanged fluid is refrigerant as an example. [0031]
When the air-conditioning apparatus 1 operates in the cooling operation mode, the flow passage of refrigerant discharged from the compressor 11 is switched by the flow passage switching device 13 in the outdoor unit 10 in such a manner that refrigerant flows through the outdoor-unit heat exchanger 14 into the indoor-unit heat exchangers 51. [0032]
In the compressor 11, low-temperature, low-pressure refrigerant is compressed, and high-temperature, high-pressure gas refrigerant is discharged. The high-temperature, high-pressure gas refrigerant discharged from the compressor
II flows through the check valve 12 and the flow passage switching device 13 into
the outdoor-unit heat exchanger 14. The refrigerant having flowed into the outdoor-
unit heat exchanger 14 exchanges heat with air that is supplied by the outdoor-unit
air-sending device 15, and high-temperature, high-pressure liquid refrigerant flows out
from the outdoor-unit heat exchanger 14.
[0033]

The high-temperature, high-pressure liquid refrigerant having flowed out from the outdoor-unit heat exchanger 14 flows through the refrigerant pipe 5 into the indoor unit 50. The high-temperature, high-pressure liquid refrigerant having flowed into the indoor unit 50 is changed into low-temperature, low-pressure liquid refrigerant or two-phase refrigerant by the expansion device 52 provided in the indoor unit 50, and the low-temperature, low-pressure liquid refrigerant or two-phase refrigerant flows into the indoor-unit heat exchanger 51. The refrigerant having flowed into the indoor-unit heat exchanger 51 exchanges heat with air that is supplied by the indoor-unit air-sending device 53, and low-temperature, low-pressure gas refrigerant flows out from the indoor-unit heat exchanger 51. Refrigerant receives heat from air in the indoor-unit heat exchanger 51, so the inside of a room that is the air-conditioned space is cooled. [0034]
The refrigerant having flowed out from the indoor-unit heat exchanger 51 passes through the refrigerant pipe 4, and flows into the outdoor unit 10. The refrigerant having flowed into the outdoor unit 10 passes through the flow passage switching device 13 and the accumulator 16, and is drawn again into the compressor 11. Subsequently, the above-described cycle is repeated. [0035] (Heating Operation Mode)
Next, the heating operation mode in which the air-conditioning apparatus 1 operates will be described. In Fig. 1, the flows of refrigerant in the heating operation mode are represented by solid arrows. Hereinafter, the heating operation mode of the air-conditioning apparatus 1 will be described in the case where heat exchanging fluid is air and heat exchanged fluid is refrigerant as an example. [0036]
When the air-conditioning apparatus 1 operates in the heating operation mode, the flow passage of refrigerant discharged from the compressor 11 is switched by the flow passage switching device 13 in the outdoor unit 10 in such a manner that the

refrigerant flows into the indoor-unit heat exchangers 51 without passing through the
outdoor-unit heat exchanger 14.
[0037]
In the compressor 11, low-temperature, low-pressure refrigerant is compressed, and high-temperature, high-pressure gas refrigerant is discharged. The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 passes through the check valve 12 and the flow passage switching device 13, and flows into the indoor-unit heat exchanger 51. The refrigerant having flowed into the indoor-unit heat exchanger 51 exchanges heat with air that is supplied by the indoor-unit air-sending device 53, and high-temperature, high-pressure liquid refrigerant flows out from the indoor-unit heat exchanger 51. The refrigerant transfers heat to air in the indoor-unit heat exchanger 51, so the inside of the room is heated. [0038]
The high-temperature, high-pressure liquid refrigerant having flowed out from the indoor-unit heat exchanger 51 is changed into low-temperature, low-pressure liquid refrigerant or two-phase refrigerant by the expansion device 52 provided in each indoor unit 50, and the low-temperature, low-pressure liquid refrigerant or the two-phase refrigerant flows into the outdoor-unit heat exchanger 14 of the outdoor unit 10. The refrigerant having flowed into the outdoor-unit heat exchanger 14 exchanges heat with air that is supplied by the outdoor-unit air-sending device 15, and low-temperature, low-pressure gas refrigerant flows out from the outdoor-unit heat exchanger 14. [0039]
The refrigerant having flowed out from the outdoor-unit heat exchanger 14 passes through the flow passage switching device 13 and the accumulator 16, and is drawn into the compressor 11 again. Subsequently, the above-described cycle is repeated. [0040] Configuration of Air-conditioning System 100>

Fig. 2 is a block diagram showing a schematic configuration of the air-conditioning system according to Embodiment 1 of the present invention. The air-conditioning system 100 includes one or a plurality of air-conditioning apparatuses 1, the centralized controller 80, and other apparatuses. The case where the air-conditioning system 100 includes a plurality of air-conditioning apparatuses 1A, 1B and 1C will be described. Hereinafter, when the air-conditioning apparatus 1A, the air-conditioning apparatus 1B, and the air-conditioning apparatus 1C do not need to be specifically distinguished from one another, description will be made while each of the air-conditioning apparatus 1A, the air-conditioning apparatus 1B, and the air-conditioning apparatus 1C is referred to as the air-conditioning apparatus 1. When components mounted on each of the air-conditioning apparatus 1A, the air-conditioning apparatus 1B, and the air-conditioning apparatus 1C do not need to be specifically distinguished from one another, description will be made without alphabets suffixed to the reference signs. The centralized controller 80 is a controller that manages the plurality of air-conditioning apparatuses 1A, 1B and 1C. In Fig. 2, the case where the three air-conditioning apparatuses 1A, 1B and 1C each including the two indoor units 50 and the single outdoor unit 10 are connected in parallel to the single centralized controller 80 is shown; however, the number of the connected air-conditioning apparatuses 1 and the number of the connected indoor units 50 are not specifically limited to this example. [0041]
The plurality of air-conditioning apparatuses 1 is communicably connected to the centralized controller 80 by communication wire or wirelessly. Specifically, a plurality of the controllers 70a, 70b and 70c is connected to the centralized controller 80. The centralized controller 80 acquires information for managing from a plurality of the outdoor units 10a, 10b and 10c and a plurality of the indoor units 50a, 50b, 50c, 50d, 50e, and 50f through the plurality of controllers 70a, 70b, and 70c. The centralized controller 80, in an emergency, is able to transmit an operation instruction related to control over the air-conditioning apparatuses 1 to the controllers 70 and

cause the controllers 70 to preferentially execute operation in accordance with the
operation instruction.
[0042]
Fig. 3 is a functional block diagram showing a functional configuration of the air-conditioning system according to Embodiment 1 of the present invention. The functions of the centralized controller 80 and each controller 70 will be described with reference to Fig. 3. In Fig. 3, the centralized controller 80 and only the controller 70a of the air-conditioning apparatus 1A are shown; however, the controller 70b and the controller 70c, as well as the controller 70a, are also connected to the centralized controller 80. [0043]
The controller 70a includes a power failure determination unit 71 and an operation control unit 72. The power failure determination unit 71 detects a power failure of the normal power supply. For example, the power failure determination unit 71 is configured to detect a power failure by constantly monitoring an electric power input from the normal power supply and detecting a phase interruption of the input electric power. When the power failure determination unit 71 detects a power failure of the normal power supply, the power failure determination unit 71 transmits a power failure signal to the centralized controller 80. When the electric power input from the normal power supply is recovered from the power failure, the power failure determination unit 71 transmits a recovery signal that is a reset signal to the centralized controller 80. [0044]
The operation control unit 72, in the normal operation mode, controls the actuators of the air-conditioning apparatus 1A on the basis of information input from the remote control, information acquired from the sensor group 60, or other information. The operation control unit 72 controls the driving frequency of the compressor 11, switching of the flow passage switching device 13, the rotation frequency of the outdoor-unit air-sending device 15, the opening degree of the expansion device 52 of each indoor unit 50, the rotation frequency of the indoor-unit

air-sending device 53 of each indoor unit 50, and other operating factors. The operation control unit 72 transmits information about the indoor units 50 and the outdoor unit 10 to the centralized controller 80, and receives an operation instruction from the centralized controller 80. Specifically, the operation control unit 72 transmits information about the operation and air-conditioning setting of each indoor unit 50, control information of the outdoor unit 10, and other information, to the centralized controller 80. When the operation control unit 72 receives an operation instruction from the centralized controller 80, the operation control unit 72 controls the air-conditioning apparatus 1A on the basis of the received operation instruction. [0045]
The centralized controller 80 includes an information management unit 81, an operating unit 82, an operation instruction unit 83, and other units. The information management unit 81 manages information about the outdoor units 10 and the indoor units 50, acquired through the controllers 70a, 70b and 70c. The information about the outdoor unit 10 contains, for example, control information of the actuators. The information about the indoor unit 50 contains, for example, information about an operation mode, an operation status such as an operating state or a stopped state, and a set temperature. The information management unit 81 is able to collectively or individually transmit such information. Furthermore, the information management unit 81 manages electric power information of the emergency power supply, and information about the priority levels of the air-conditioning apparatuses 1. The electric power information contains, for example, a set electric power Ps set in advance as an electric power with which the emergency power supply is able to supply the air-conditioning system 100, and the amount of electric power that can be allocated to the air-conditioning system 100. The priority level is a priority level determined for which an operation is continued in the event of a power failure of the normal power supply. The priority level may be set in advance through the operating unit 82 or another device at the time of, for example, installation or other timing or may be set by the operation instruction unit 83 on the basis of the operation

information of each air-conditioning apparatus 1 during operation, or other
information.
[0046]
The operating unit 82 is a unit that a manager, or another user, of the air-conditioning system 100 uses to input an instruction or a setting and is made up of, for example, a touch panel having a liquid crystal display screen, a set of a display unit and a keyboard, or other configurations. The input setting is incorporated into the information management unit 81. The input instruction is executed by the operation instruction unit 83 as needed. [0047]
The operation instruction unit 83 manages the operation of the plurality of air-conditioning apparatuses 1A, 1B and 1C that are connected to the centralized controller 80. In the normal operation mode, the operation of each air-conditioning apparatus 1 is controlled by the corresponding one of the controllers 70 on the basis of information input or set from the remote control and information from the sensor group 60 or other devices. The operation instruction unit 83 receives a power failure signal from the power failure determination unit 71. When the normal power supply fails, the operation instruction unit 83 switches the operation mode from the normal operation mode to an electric power limited operation mode. The electric power limited operation mode is an operation mode in which an electric power that the connected air-conditioning apparatus 1 uses is limited on the basis of the set electric power Ps set in advance. During electric power limited operation, the operation instruction unit 83, where necessary, transmits an operation instruction to the controller 70, and causes the operation control unit 72 to control the air-conditioning apparatus 1 on the basis of the operation instruction. Specifically, the operation instruction unit 83 causes the operation control unit 72 to control the operation of the one or plurality of air-conditioning apparatuses 1 within the range in which the total usage electric power Pu of one or a plurality of connected air-conditioning apparatuses 1 A, 1B and 1C is lower than or equal to the set electric power Ps. The

operation instruction unit 83 also ends the electric power limited operation when the
operation instruction unit 83 receives a recovery signal.
[0048]

Fig. 4 is a flowchart showing control of the air-conditioning system according to Embodiment 1 of the present invention. Hereinafter, control that the centralized controller 80 and the controller 70 execute in the air-conditioning system 100 will be described. [0049]
When the air-conditioning system 100 starts the operation, normal operation is performed (step ST101). The power failure determination unit 71 is monitoring an electric power input from the normal power supply, and, during normal operation, determines whether a power failure of the normal power supply is detected (step ST102). When a power failure of the normal power supply is detected by the power failure determination unit 71 (YES in step ST102), a power failure signal is transmitted to the centralized controller 80. When the centralized controller 80 receives the power failure signal, the electric power limited operation is started by the operation instruction unit 83 (step ST103). On the other hand, when no power failure is detected by the power failure determination unit 71 (NO in step ST102), normal operation is continued (step ST101), and the power failure determination of step ST102 is repeated at predetermined time intervals. [0050]
In the electric power limited operation, the operation instruction unit 83 limits the usage electric power of the air-conditioning system 100 in such a manner that the usage electric power is lower than or equal to the electric power that is supplied by the emergency power supply. First, the operation instruction unit 83 carries out electric power determination as to whether the usage electric power Pu is higher than the set electric power Ps (step ST104). At this time, the operation instruction unit 83 transmits a request signal to each of the controllers 70a, 70b and 70c, the signal requesting each of the controllers 70a, 70b and 70c to notify the operation instruction

unit 83 of information about the electric power of the corresponding one of the air-conditioning apparatuses 1. When the controller 70 receives the request signal, the operation control unit 72 calculates the amount of electric power on the basis of the operation frequency of the compressor 11, the rotation frequency of the outdoor-unit air-sending device 15, and other factors, and notifies the centralized controller 80 of the calculated amount of electric power. The operation instruction unit 83 adds up the provided amounts of electric power of the air-conditioning apparatuses 1A, 1B and 1C, and then compares the usage electric power Pu obtained by addition with the set electric power Ps set in the information management unit 81. [0051]
When the operation instruction unit 83 determines in the electric power determination that the usage electric power Pu is lower than or equal to the set electric power Ps (NO in step ST104), the operation instruction unit 83 does not need to limit the operation of the air-conditioning apparatus 1, so the current operation statuses of the air-conditioning apparatuses 1A, 1B and 1C are maintained. On the other hand, when it is determined that the usage electric power Pu is higher than the set electric power Ps (YES in step ST104), the operation instruction unit 83 further determines whether a plurality of the air-conditioning apparatuses 1 is in operation (step ST105). When only one air-conditioning apparatus 1 is in operation (NO in step ST105), the operation instruction unit 83 starts the electric power limited operation for single operation (step ST201). [0052]
On the other hand, when a plurality of the air-conditioning apparatuses 1 is in operation (YES in step ST105), the operation instruction unit 83 stops the operation of the air-conditioning apparatus 1 whose priority level is the lowest among the plurality of air-conditioning apparatuses 1 in operation (step ST106). At this time, the operation instruction unit 83 makes reference to the priority level of each air-conditioning apparatus 1, stored in the information management unit 81, and transmits, to the controller 70, an operation instruction to stop the operation of the air-conditioning apparatus 1 whose priority level is the lowest. Specifically, when the

priority level "high", "middle", and "low" are set for the air-conditioning apparatus 1A, the air-conditioning apparatus 1B, and the air-conditioning apparatus 1C, respectively, an operation instruction to stop the operation of the air-conditioning apparatus 1C whose set priority level is "low" is transmitted. The controller 70c of the air-conditioning apparatus 1C stops the actuators of the air-conditioning apparatus 1C on the basis of the operation instruction. On the other hand, the operation of the air-conditioning apparatus 1A and air-conditioning apparatus 1B is continued. [0053]
After step ST106 or when the current operation statuses of the air-conditioning apparatuses 1 A, 1B and 1C are maintained as a result of the electric power determination of step ST104, power failure recovery determination is carried out (step ST107). The power failure determination unit 71 determines that a power failure is recovered when the electric power input from the normal power supply is recovered (YES in step ST107), and transmits a recovery signal to the centralized controller 80. When the operation instruction unit 83 receives the recovery signal from the power failure determination unit 71, the operation instruction unit 83 ends the electric power limited operation (step ST108). Subsequently, the normal operation is performed (step ST101). On the other hand, when the recovery signal is not transmitted from the power failure determination unit 71 (NO in step ST107), the operation instruction unit 83 carries out the electric power determination of step ST104 again. Until the centralized controller 80 receives a recovery signal, the process from step ST104 to step ST107 is repeated. For example, as the air-conditioning apparatus 1C is stopped, a total usage electric power Pu2 obtained through addition of the second electric power determination (step ST104) is lower than a usage electric power Pu1 during the last electric power determination. Even after the air-conditioning apparatus 1C is stopped, when the usage electric power Pu2 is higher than the set electric power Ps, the air-conditioning apparatus 1B whose set priority level is the second lowest is stopped in step ST106 for the second time. [0054]

Fig. 5 is a flowchart showing control for electric power limited operation for single operation of the air-conditioning system according to Embodiment 1 of the present invention. Hereinafter, the electric power limited operation when only the single air-conditioning apparatus 1A is in operation will be described. The electric power limited operation for single operation limits the power consumption of the air-conditioning apparatus 1 in operation to the set electric power Ps or below. [0055]
When the electric power limited operation for single operation starts (step ST201), the operation instruction unit 83 calculates the frequency Fs of the compressor 11 and the rotation frequency Ns of the outdoor-unit air-sending device 15 when the air-conditioning apparatus 1 is operated at the set electric power Ps set in advance (step ST202). The operation instruction unit 83 sets the calculated frequency Fs as the upper limit frequency of the compressor 11, and sets the calculated rotation frequency Ns as the upper limit rotation frequency of the outdoor-unit air-sending device 15 for the air-conditioning apparatus 1A in operation (step ST203). At this time, the operation instruction unit 83 incorporates the set upper limit frequency and upper limit rotation frequency into the information management unit 81, and transmits the set upper limit frequency and upper limit rotation frequency to the controller 70a as an operation instruction. The operation control unit 72 controls the compressor 11 and outdoor-unit air-sending device 15 of the air-conditioning apparatus 1A in operation with the frequency Fs and the rotation frequency Ns set as upper limits on the basis of the operation instruction. When setting of step ST203 ends, power failure recovery determination is carried out (step ST204). The power failure determination unit 71 determines that a power failure is recovered when the electric power input from the normal power supply is returned (YES in step ST204), and transmits a recovery signal to the centralized controller 80. When the operation instruction unit 83 receives the recovery signal from the power failure determination unit 71, the operation instruction unit 83 ends the electric power limited operation (step ST205). Subsequently, the normal operation is performed (step ST101). On the other hand, when the recovery signal is not received from the power failure

determination unit 71 (NO in step ST204), the electric power limited operation is continued on the basis of the set upper limit frequency and upper limit rotation frequency. Subsequently, until the centralized controller 80 receives a recovery signal, the power failure recovery determination of step ST204 is repeated. [0056]
As described above, in Embodiment 1, the air-conditioning system 100 includes the operation control unit 72, the power failure determination unit 71, and the operation instruction unit 83. When a power failure is detected by the power failure determination unit 71, the operation instruction unit 83 executes the electric power limited operation that limits the electric power that the one or plurality of air-conditioning apparatuses 1A, 1B and 1C use on the basis of the upper limit electric power (set electric power Ps). When the electric power limited operation is being executed by the operation instruction unit 83, the operation control unit 72 controls the operation of the one or plurality of air-conditioning apparatuses 1 within the range in which the total usage electric power Pu of the one or plurality of air-conditioning apparatuses 1 A, 1B and 1C is lower than or equal to the upper limit electric power (set electric power Ps). [0057]
Thus, during a power failure of the normal power supply, the total electric power consumption is limited on the basis of the upper limit electric power (set electric power Ps) set in advance; however, the operation control unit 72 is able to control the operation within the range that does not exceed the upper limit electric power. For example, when the electric power that is supplied from the emergency power supply is set as the upper limit electric power, the air-conditioning system 100 is able to perform the operation at the maximum air-conditioning capacity within the range of the electric power supplied. Consequently, as compared to the power suppression operation mode set as in the case of the existing art, the flexibility of control during usage of the emergency power supply increases, and a stop of the operation of the system as a whole is avoided by limiting the total usage electric power Pu to the upper limit electric power (set electric power Ps) or below. That is, even when the

electric power supplied is limited, the air-conditioning system 100 is able to continue
the operation depending on the set electric power Ps.
[0058]
The power failure determination unit 71 detects a power failure when the power failure determination unit 71 detects a phase interruption of the normal power supply. Thus, an abnormal state of input electric power is detected in an early stage, so the air-conditioning system 100 is able to perform stable operation by switching over to maintenance or an emergency power supply. [0059]
The air-conditioning system 100 further includes the centralized controller 80 that manages the one or plurality of air-conditioning apparatuses 1 A, 1B and 1C, and the operation instruction unit 83 is included in the centralized controller 80. Thus, the air-conditioning system 100 is able to execute the electric power limited operation or transmit an operation instruction by using the operation information of the one or plurality of air-conditioning apparatuses 1 A, 1B and 1C that the centralized controller 80 manages. [0060]
When a power failure is detected by the power failure determination unit 71 and the total usage electric power Pu of the one or plurality of air-conditioning apparatuses 1 A, 1B and 1C is higher than the upper limit electric power (set electric power Ps), the operation instruction unit 83 executes the electric power limited operation. [0061]
Thus, the air-conditioning system 100 is able to continue the operation through limiting the total usage electric power Pu when the electric power supplied is insufficient during a power failure of the normal power supply, and execute highly efficient operation by performing, for example, normal operation until the total usage electric power Pu becomes the set electric power Ps. [0062]

When a plurality of the air-conditioning apparatuses 1A, 1B and 1C is in operation during the electric power limited operation, the operation instruction unit 83 causes the operation control unit 72 to stop the operation of the air-conditioning apparatus (for example, the air-conditioning apparatus 1C) whose priority level is lower among the plurality of air-conditioning apparatuses 1 in operation. [0063]
Thus, when a plurality of the air-conditioning apparatuses 1A, 1B and 1C is in operation during the electric power limited operation, the total usage electric power Pu is limited on the basis of the priority level. Consequently, the air-conditioning system 100 is able to continue the operation of the air-conditioning apparatus intended to be prioritized (for example, the air-conditioning apparatus 1A) even in an emergency. [0064]
Each of the one or plurality of air-conditioning apparatuses 1 A, 1B and 1C includes the compressor 11 and the outdoor-unit air-sending device 15. The operation control unit 72 controls the compressor 11 and the outdoor-unit air-sending device 15. When only one of the one or plurality of air-conditioning apparatuses 1A, 1B and 1C (air-conditioning apparatus 1A) is in operation under the electric power limited operation, the operation instruction unit 83 calculates the frequency of the compressor 11 and the rotation frequency of the outdoor-unit air-sending device 15 for the upper limit electric power (for example, the set electric power Ps). The operation instruction unit 83 causes the operation control unit 72 to control the compressor 11 and outdoor-unit air-sending device 15 of the air-conditioning apparatus 1A in operation with the calculated frequency Fs and rotation frequency Ns set as upper limits. [0065]
Thus, the operation control unit 72 is able to control the compressor 11 and the outdoor-unit air-sending device 15 at any frequency and rotation frequency under the electric power limited operation with the frequency Fs and the rotation frequency Ns for the set electric power Ps being set as upper limits. Consequently, as compared

to the power suppression operation mode in which the operation is performed at the set frequency of the compressor and the set rotation frequency of the indoor-unit air-sending device as in the case of the existing art, the air-conditioning system 100 is able to provide highly efficient air conditioning within the set range even during usage of the emergency power supply. [0066]
The embodiment of the present invention is not limited to Embodiment 1, and may be modified into various forms. For example, in Embodiment 1, each of the plurality of air-conditioning apparatuses 1 A, 1B and 1C includes the controller 70, and the centralized controller 80 manages the plurality of air-conditioning apparatuses 1 A, 1B and 1C; however, the embodiment is not limited to this configuration. When the air-conditioning system 100 is made up of the single air-conditioning apparatus 1, the controller 70 may include the functions of the centralized controller 80. [0067]
The refrigeration cycle is not limited to the circuit configuration of Fig. 1. For example, the outdoor unit 10 may include a mechanism of switching the flows of refrigerant for each indoor unit 50. [0068]
The centralized controller 80 may include part or all of the functions of the controller 70 or the controller 70 may include part or all of the functions of the centralized controller 80. For example, a power failure or a power failure recovery may be determined by the centralized controller 80 instead of the controller 70. [0069]
In step ST104, the operation instruction unit 83 transmits a request signal to each controller 70, the signal requesting each controller 70 to notify the operation instruction unit 83 of information about the usage electric power of the corresponding one of the air-conditioning apparatuses 1. Instead, already acquired information may be used. The operation instruction unit 83 may be configured to calculate the usage electric power of each air-conditioning apparatus 1 and the total usage electric

power Pu on the basis of the latest operation information stored in the information management unit 81. [0070] Embodiment 2
Fig. 6 is a flowchart showing control for defrosting operation during electric power limited operation of an air-conditioning system according to Embodiment 2 of the present invention. In Embodiment 2, each of the air-conditioning apparatuses 1A, 1B and 1C performs defrosting operation in addition to the above-described heating operation and cooling operation. Each of the air-conditioning apparatuses 1A, 1B and 1C further includes a refrigerant temperature sensor as the sensor group 60. The refrigerant temperature sensor is disposed at the outdoor-unit heat exchanger 14, and measures the temperature of refrigerant flowing through the outdoor-unit heat exchanger 14. In the air-conditioning apparatus 1, when the amount of frost formation of the outdoor-unit heat exchanger 14 increases in the heating operation mode, defrosting operation for removing frost is performed. [0071]
The operation control unit 72 of the controller 70 controls the operation of the air-conditioning apparatus 1 in such a manner that defrosting operation starts, for example, when the temperature of refrigerant, measured by the refrigerant temperature sensor, becomes lower than or equal to a set temperature. The operation control unit 72 controls the operation of the air-conditioning apparatus 1 in such a manner that defrosting operation ends and heating operation resumes when set defrosting time Tdef has elapsed since the start of the defrosting operation. In the defrosting operation, the operation control unit 72 controls the operation of the air-conditioning apparatus 1 in such a manner that the compressor 11 operates at a set defrosting frequency Fdef. The condition to start the defrosting operation is not limited to the determination on the basis of the temperature of refrigerant. For example, a low-pressure sensor may be disposed to the suction port of the compressor 11, and, when the pressure of refrigerant, measured by the low-pressure

sensor becomes lower than or equal to a set pressure, the defrosting operation may
be started.
[0072]
The defrosting time Tdef is the duration of defrosting operation each time. Set values determined on the basis of the amount of heat required to defrost each of the outdoor-unit heat exchangers 14 are stored in advance in the corresponding one of the controllers 70a, 70b and 70c of the air-conditioning apparatuses 1A, 1B and 1C as the defrosting frequency Fdef and the defrosting time Tdef. Hereinafter, a set frequency Fdef 1 is stored as a set value of the defrosting frequency Fdef and set defrosting time Tdef1 is stored as a set value of the defrosting time Tdef in the controller 70a of the air-conditioning apparatus 1A. [0073]
The centralized controller 80 acquires the above-describe set values of the defrosting frequency Fdef and defrosting time Tdef, and these acquired set values are managed by the information management unit 81 as information about the outdoor unit 10. [0074] (Defrosting Operation)
When the controller 70 executes the defrosting operation in the air-conditioning apparatus 1, the controller 70 controls the operation of the air-conditioning apparatus 1 in such a manner that the flow passage switching device 13 switches the flow passage to that in the cooling operation mode, and the outdoor-unit air-sending device 15 and the indoor-unit air-sending devices 53 stop. The controller 70 controls the compressor 11 in such a manner that the compressor 11 operates at the set defrosting frequency Fdef. For example, during normal times, the defrosting frequency Fdef is set to the maximum frequency of the compressor 11 for removing frost in a short period of time. [0075]
When the defrosting operation is being performed, low-temperature, low-pressure refrigerant is compressed by the compressor 11, and high-temperature,

high-pressure gas refrigerant is discharged from the compressor 11. The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 passes through the check valve 12 and the flow passage switching device 13 and flows into the outdoor-unit heat exchanger 14. The refrigerant having flowed into the outdoor-unit heat exchanger 14 transfers heat to remove frost, and liquid refrigerant flows out from the outdoor-unit heat exchanger 14. [0076]
The liquid refrigerant having flowed out from the outdoor-unit heat exchanger 14 passes through the refrigerant pipe 5 and flows into the indoor unit 50. The liquid refrigerant having flowed into the indoor unit 50 passes through the expansion device 52 provided in the indoor unit 50, and flows into the indoor-unit heat exchanger 51. The refrigerant having flowed into the indoor-unit heat exchanger 51 evaporates with heat of the pipe, part or all of the refrigerant becomes gas refrigerant, and the gas refrigerant flows out from the indoor-unit heat exchanger 51. The refrigerant having flowed out from the indoor-unit heat exchanger 51 passes through the refrigerant pipe 4 and flows into the outdoor unit 10. The refrigerant having flowed into the outdoor unit 10 passes through the flow passage switching device 13 and the accumulator 16, and is drawn again into the compressor 11. Subsequently, the above-described cycle is repeated until the defrosting operation ends. [0077]
Incidentally, in the existing air-conditioning system, the usage electric power is suppressed by uniformly setting the compressors at the lowest frequency. Under the electric power suppression operation for single operation of Embodiment 1, the upper limit of the operation frequency of the compressor 11 is limited to the frequency Fs. For this reason, in the electric power suppression operation mode in which the compressor 11 is driven at a frequency lower than the defrosting frequency Fdef during normal times, frost may be not removed sufficiently even when the defrosting operation is performed for the defrosting time Tdef during normal times.

Consequently, in Embodiment 2, when the defrosting operation is performed under the electric power limited operation, the defrosting time Tdef required to defrost the outdoor-unit heat exchanger 14 is calculated, and the defrosting operation is performed for the calculated defrosting time Tdef. Hereinafter, control in the case where the defrosting operation is performed while the electric power limited operation for single operation of Fig. 5 is being performed will be described as an example with reference to Fig. 6. In this case, only the air-conditioning apparatus 1A is in operation and the air-conditioning apparatus 1A is performing heating operation while the power failure recovery determination of step ST204 of Fig. 5 is repeated. When the condition to start the defrosting operation is satisfied in the air-conditioning apparatus 1A and the operation control unit 72 executes the defrosting operation, control of Fig. 6 is started. [0079]
First, the operation instruction unit 83 calculates a defrosting frequency Fs2 of the compressor 11 when the air-conditioning apparatus 1A operates at the set electric power Ps set in advance (step ST301). The operation instruction unit 83 calculates required defrosting time Ts that is required when the defrosting operation is performed in the air-conditioning apparatus 1A by driving the compressor 11 at the calculated defrosting frequency Fs2 (step ST302). [0080]
A method of calculating the required defrosting time Ts will be described. The amount of heat Q required to defrost the outdoor-unit heat exchanger 14 of the air-conditioning apparatus 1A is expressed by the following mathematical expression (1) by using the set defrosting time Tdef1 that is set for the defrosting operation during normal times. [0081] [Mathematical Expression 1]
Q = Gr x Tdef1 x AH (1)
Gr: refrigerant flow rate
AH: difference in enthalpy between before and after heat exchange

The refrigerant flow rate Gr in the above mathematical expression (1) is expressed by the following mathematical expression (2) by using the set frequency Fdef1 that is set for the defrosting operation during normal times. [0082] [Mathematical Expression 2]
Gr = V x r|v x Fdef1 x p (2)
V: displacement of the compressor 11
r|v: volumetric efficiency
p: refrigerant density
That is, to obtain the amount of heat Q required to defrost the outdoor-unit heat exchanger 14 of the air-conditioning apparatus 1A, the product of the defrosting frequency Fdef and the defrosting time Tdef should be constant. That is, the relationship expressed by the following mathematical expression (3) holds. [0083] [Mathematical Expression 3]
Fdef1 x Tdef1 = Fs2 x Ts (3)
Consequently, the required defrosting time Ts that is required when the compressor 11 is driven at the defrosting frequency Fs2 during defrosting operation under the electric power limited operation is calculated by the following mathematical expression (4). [0084] [Mathematical Expression 4]
Ts = (Fdef1 x Tdef1)/Fs2 (4)
After step ST302, the operation instruction unit 83 transmits an operation instruction to the controller 70a of the air-conditioning apparatus 1 A, and the operation control unit 72 of the controller 70a executes the defrosting operation on the basis of the operation instruction received from the operation instruction unit 83 (step ST303). At this time, the operation control unit 72 controls the operation of the air-conditioning apparatus 1A in such a manner that the flow passage switching device 13 switches the flow passage to that in the cooling operation mode, the outdoor-unit

air-sending device 15 stops, and the compressor 11 operates at the calculated defrosting frequency Fs2 on the basis of the operation instruction. When the required defrosting time Ts has elapsed since the start of the defrosting operation, the operation control unit 72 ends the defrosting operation. At this time, the operation control unit 72 controls the operation of the air-conditioning apparatus 1A in such a manner that heating operation resumes by switching the flow passage to that in the heating operation mode by the flow passage switching device 13. [0085]
The operation control unit 72, during execution of heating operation, controls the operation frequency of the compressor 11 with the frequency Fs set as an upper limit and controls the rotation frequency of the outdoor-unit heat exchanger 14 with the rotation frequency Ns set as an upper limit. Subsequently, while the power failure recovery determination of step ST204 of Fig. 5 is being repeated, the operation control unit 72 interrupts heating operation when the condition to start the defrosting operation is satisfied, and executes the defrosting operation of step ST303 of Fig. 6. [0086]
In the configuration that the defrosting operation is performed during the electric power limited operation for single operation as described above, step ST301 may be omitted, and the required defrosting time for the upper limit frequency Fs may be calculated in step ST302. [0087]
The electric power limited operation for single operation is described; however, when a plurality of the air-conditioning apparatuses (for example, the air-conditioning apparatus 1A and the air-conditioning apparatus 1B) is in operation during electric power limited operation as well, efficient operation may be performed at or below the set electric power Ps through control of Fig. 5 and Fig. 6. In this case, for example, the operation instruction unit 83 should allocate usable electric power to each of the air-conditioning apparatuses 1A and 1B in such a manner that the total usage electric power Pu of the plurality of air-conditioning apparatuses 1A and 1B kept in operation becomes lower than or equal to the set electric power Ps. The operation instruction

unit 83 calculates the frequency Fs of the compressor 11 and the rotation frequency Ns of the outdoor-unit air-sending device 15 for the allocated electric power in step ST202 of Fig. 5, and calculates the defrosting frequency Fs2 of the compressor 11 for the allocated electric power in step ST301 of Fig. 6. The electric power that is allocated to each of the air-conditioning apparatuses 1A and 1B may be determined by dividing the set electric power Ps by the number of the plurality of air-conditioning apparatuses 1A and 1B kept in operation. With such a configuration, even when the plurality of air-conditioning apparatuses 1A and 1B is in operation under the electric power limited operation, cooling operation, heating operation, and defrosting operation are efficiently performed within the range of the electric power allocated to each of the plurality of air-conditioning apparatuses 1A and 1B. [0088]
As described above, in Embodiment 2, when the electric power limited operation is being executed by the operation instruction unit 83, the operation control unit 72 controls the defrosting operation within the range in which the total usage electric power Pu of the one or plurality of air-conditioning apparatuses 1A and 1B and 1C is lower than or equal to the upper limit electric power (set electric power Ps). Thus, even when the defrosting operation is performed in the air-conditioning apparatus 1 in operation, the operation is controlled within the range that does not exceed the upper limit electric power by the operation control unit 72 while the total usage electric power Pu is limited to the upper limit electric power (set electric power Ps) or below. [0089]
The operation control unit 72, during defrosting operation, controls the operation of the air-conditioning apparatus 1 in such a manner that the compressor 11 operates at the set frequency Fdef1 set in advance. When only the air-conditioning apparatus 1A is in operation under the electric power limited operation and the air-conditioning apparatus 1A performs the defrosting operation, the operation instruction unit 83 calculates a defrosting frequency Fs2 of the compressor 11 for the upper limit electric power (set electric power Ps). The operation instruction unit 83 causes the

operation control unit 72 to control the operation of the air-conditioning apparatus 1 in such a manner that the compressor 11 operates at the calculated defrosting frequency Fs2. Thus, as the defrosting operation is performed by driving the compressor 11 at the upper limit electric power within the range of the electric power that is supplied under the electric power limited operation, the outdoor-unit heat exchanger 14 is efficiently defrosted within the range of the electric power supplied even during the electric power limited operation. [0090]
The operation control unit 72 controls the operation of the air-conditioning apparatus 1 in such a manner that the defrosting operation is executed for the set defrosting time Tdef1 and then ends the defrosting operation. When only one air-conditioning apparatus 1A is in operation under the electric power limited operation and the air-conditioning apparatus 1A performs defrosting operation, the operation instruction unit 83 causes the operation control unit 72 to control the operation of the air-conditioning apparatus 1A in such a manner that the defrosting operation is executed for the required defrosting time Ts that is longer than the set defrosting time Tdef1. Thus, as the defrosting operation during the electric power limited operation is performed longer than that during normal times, a decrease in heat exchange efficiency due to frost formation is suppressed by removing frost on the outdoor-unit heat exchanger 14 even when the operation frequency of the compressor 11 is limited under the electric power limited operation. [0091]
The operation instruction unit 83 calculates the required defrosting time Ts by dividing the product of the set frequency Fdef1 and the set defrosting time Tdef1 by the calculated defrosting frequency Fs2. Thus, frost is reliably removed by ensuring the amount of heat Q required to defrost the outdoor-unit heat exchanger 14. Reference Signs List [0092]
1 (1A, 1B, 1C) air-conditioning apparatus 4 refrigerant pipe 5 refrigerant pipe 10 (10a, 10b, 10c) outdoor unit 11 compressor 12 check

valve 13 flow passage switching device 14 outdoor-unit heat exchanger 15 outdoor-unit air-sending device 16 accumulator 50 (50a, 50b, 50c, 50d, 50e, 50f) indoor unit 51 (51a, 51b) indoor-unit heat exchanger 52 (52a, 52b) expansion device 53 (53a, 53b) indoor-unit air-sending device 60 sensor group 70 (70a, 70b, 70c) controller 71 power failure determination unit 72 operation control unit 80 centralized controller 81 information management unit 82 operating unit 83 operation instruction unit 100 air-conditioning system Fdef defrosting frequency Fdef1 set frequency Fs frequency Fs2 calculated defrosting frequency Ns rotation frequency Ps set electric power Pu, Pu1, Pu2 usage electric power Q amount of heat Tdef defrosting time Tdef1 set defrosting time Ts required defrosting time

WE CLAIM:
[Claim 1]
An air-conditioning system comprising:
one or a plurality of air-conditioning apparatuses configured to operate when the one or plurality of air-conditioning apparatuses receive electric power that is supplied from a normal power supply during normal times and to operate when the one or plurality of air-conditioning apparatuses receive electric power that is supplied from an emergency power supply during a power failure of the normal power supply;
an operation control unit configured to control an operation of the one or plurality of air-conditioning apparatuses;
a power failure determination unit configured to detect a power failure of the normal power supply; and
an operation instruction unit configured to, when a power failure is detected by the power failure determination unit, execute an electric power limited operation that limits an electric power that the one or plurality of air-conditioning apparatuses use on a basis of an upper limit electric power set in advance,
the operation control unit being configured to, when the electric power limited operation is being executed by the operation instruction unit, control the operation of the one or plurality of air-conditioning apparatuses within a range in which a total usage electric power of the one or plurality of air-conditioning apparatuses is lower than or equal to the upper limit electric power. [Claim 2]
The air-conditioning system of claim 1, wherein the power failure determination unit is configured to detect a power failure when the power failure determination unit detects a phase interruption of the normal power supply. [Claim 3]
The air-conditioning system of claim 1 or 2, further comprising
a centralized controller configured to manage the one or plurality of air-conditioning apparatuses, wherein
the operation instruction unit is included in the centralized controller.

[Claim 4]
The air-conditioning system of any one of claims 1 to 3, wherein the operation instruction unit is configured to, when a power failure is detected by the power failure determination unit and the total usage electric power is higher than the upper limit electric power, execute the electric power limited operation. [Claim 5]
The air-conditioning system of any one of claims 1 to 4, wherein the operation instruction unit is configured to, when the plurality of air-conditioning apparatuses is in operation under the electric power limited operation, limit the total usage electric power by causing the operation control unit to stop the operation of the air-conditioning apparatus whose set priority level is lower among the plurality of air-conditioning apparatuses in operation. [Claim 6]
The air-conditioning system of any one of claims 1 to 5, wherein
the one or plurality of air-conditioning apparatuses each include a compressor configured to compress refrigerant, and
the operation control unit is configured to control the compressor. [Claim 7]
The air-conditioning system of claim 6, wherein
the one or plurality of air-conditioning apparatuses each include an outdoor-unit air-sending device,
the operation control unit is configured to control the outdoor-unit air-sending device, and
the operation instruction unit is configured to, when only one of the one or plurality of air-conditioning apparatuses is in operation under the electric power limited operation, calculate a frequency of the compressor and a rotation frequency of the outdoor-unit air-sending device for the upper limit electric power, and to cause the operation control unit to control the compressor and outdoor-unit air-sending device of the air-conditioning apparatus in operation with the calculated frequency and rotation frequency set as upper limits.

[Claim 8]
The air-conditioning system of claim 6 or 7, wherein the operation control unit is configured to, when the electric power limited operation is being executed by the operation instruction unit, control a defrosting operation of the one or plurality of air-conditioning apparatuses within the range in which the total usage electric power of the one or plurality of air-conditioning apparatuses is lower than or equal to the upper limit electric power. [Claim 9]
The air-conditioning system of claim 8, wherein
the one or plurality of air-conditioning apparatuses each include a flow passage switching device configured to switch flow passages of refrigerant from the compressor and an outdoor-unit heat exchanger configured to exchange heat between refrigerant and heat exchanging fluid,
the operation control unit is configured to, during the defrosting operation, control the flow passage switching device in such a manner that a discharge port of the compressor is connected to the outdoor-unit heat exchanger and to control the compressor in such a manner that the compressor operates at a set frequency that is set in advance, and
the operation instruction unit is configured to, when only one of the one or plurality of air-conditioning apparatuses is in operation under the electric power limited operation and the air-conditioning apparatus in operation performs the defrosting operation, calculate a defrosting frequency of the compressor for the upper limit electric power, and to cause the operation control unit to control the compressor in such a manner that the compressor operates at the calculated defrosting frequency. [Claim 10]
The air-conditioning system of claim 9, wherein
the operation control unit is configured to control the defrosting operation in such a manner that the defrosting operation is executed for set defrosting time that is set in advance and the defrosting operation ends, and

the operation instruction unit is configured to, when only one of the one or plurality of air-conditioning apparatuses is in operation under the electric power limited operation and the air-conditioning apparatus in operation performs the defrosting operation, cause the operation control unit to control the defrosting operation in such a manner that the defrosting operation is executed for required defrosting time that is longer than the set defrosting time. [Claim 11]
The air-conditioning system of claim 10, wherein the operation instruction unit is configured to calculate the required defrosting time by dividing a product of the set frequency and the set defrosting time by the calculated defrosting frequency.