US20140374497A1

US20140374497A1 - Heat source system, control device thereof, and control method thereof

Info

Publication number: US20140374497A1
Application number: US14/376,594
Authority: US
Inventors: Satoshi Nikaido; Kenji Ueda; Kazuki Wajima; Yasushi Hasegawa; Yoshie Togano
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2012-03-30
Filing date: 2013-01-31
Publication date: 2014-12-25
Also published as: CN104126098A; JP5984456B2; DE112013001841T5; WO2013145844A1; JP2013210149A; KR20140108576A

Abstract

A technique of suppressing power consumption of a system so as to be equal to or less than contracted power when a refrigerator is used as a heat source is provided. A system control device (20) includes a power monitoring unit (23) that monitors power consumption of a heat source system and a demand restricting unit (24). The demand restricting unit (24) performs demand restriction by raising or lowering a set temperature so as to decrease power consumption of heat source equipment when the power consumption of the heat source system is greater than a first power threshold value set to a value lower than the contracted power.

Description

TECHNICAL FIELD

The present invention relates to a heat source system, a control device thereof, a control method thereof, a power adjustment network system, and a control device of heat source equipment.

BACKGROUND ART

In recent years, an air-conditioning system has been proposed which performs a demand control so that power consumption does not exceed power contracted with an electric power company.
For example, PTL 1 discloses a method of lowering an operating frequency of a compressor of one piece of outdoor equipment when a current value of a power supply line is greater than a current limit value in the demand control of plural pieces of outdoor equipment connected to the same power supply line.

CITATION LIST

Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No. 10-339529

SUMMARY OF INVENTION

Technical Problem

Recently, a large-scale air-conditioning facility introduced into a building or the like is known which uses a turbo refrigerator as a heat source. In such a large-scale air-conditioning facility using a turbo refrigerator as a heat source, the total power of a system may be contracted and thus the power consumption of the system needs to be controlled so as not to be greater than the contracted power.
An object of the present invention is to provide a heat source system that can suppress system power consumption so as to be equal to or less than contracted power when a refrigerator is used as a heat source, a control device thereof, a control method thereof, a power adjustment network system, and a control device of heat source equipment.

Solution to Problem

According to a first aspect of the present invention, there is provided a control device of a heat source system having at least one piece of heat source equipment that heats or cools heat source water depending on a set temperature and that supplies the heated or cooled heat source water to load equipment, including: power monitoring means for monitoring power consumption of the heat source system; and demand restricting means for performing demand restriction by raising or lowering the set temperature so as to decrease power consumption of the heat source equipment when the power consumption of the heat source system is greater than a first power threshold value set to a value lower than that of contracted power.
According to the first aspect, when the power consumption of the heat source system is greater than the first power threshold value which is set to a value lower than the contracted power, the set temperature is forced to rise or fall so as to reduce the power consumption of the heat source equipment by the demand restricting means. Accordingly, a temperature difference (=a refrigerant pressure difference between an evaporator and a condenser) between a coolant outlet temperature and a heat source water supply temperature of the heat source equipment is reduced and it is thus possible to reduce a head differential pressure of a compressor. Since the difference between an inflow temperature and a supply temperature of heat source water is reduced, necessary cooling capability is also reduced. As a result, it is possible to suppress the power consumption of the heat source equipment. Since the heat source equipment is inherently controlled on the basis of the cooling capability (the heat source water outlet temperature of the heat source equipment), it is possible to smoothly perform an equipment control by controlling the set temperature of heat source water as described above.
In the control device of a heat source system, the demand restricting means may lower or raise the set temperature so as to increase the power consumption of the heat source equipment when the power consumption of the heat source system is less than a second power threshold value set to a value equal to or less than the first power threshold value, and may maintain the set temperature when a current set temperature reaches a predetermined reference set temperature.
According to this configuration, when the power consumption of the heat source system is less than the second power threshold value which is set to be equal to or less than the first power threshold value, the set temperature is forced to rise or fall so as to increase the power consumption of the heat source equipment. Accordingly, it is possible to cause the temperature of the heat source water to approach the reference set temperature.
In the control device of a heat source system, the demand restricting means may lower the set temperature so as not to be less than a predetermined lower limit value when the heat source equipment heats the heat source water, and may raise the set temperature so as not to be greater than a predetermined upper limit value when the heat source equipment cools the heat source water.
According to this configuration, the set temperature is provided with a limit value, and a control of maintaining the limit value is performed when the set temperature is changed by the demand restricting means and the set temperature reaches the limit value. Accordingly, it is possible to prevent the temperature of the heat source water supplied to the load equipment from exceeding the limit value.
The control device of a heat source system may further include demand restriction stopping means for stopping the demand restriction by the demand restricting means.
According to this configuration, when the performing of the demand restriction is not desired, the demand restriction can be stopped by activating the demand restriction stopping means.
The control device of a heat source system may further include electrical water supply means for adjusting a flow rate of the heat source water supplied from an external apparatus to the heat source equipment, and the demand restricting means may hold a rotation speed of the water supply means in a period in which the power consumption of the heat source system is greater than the first power threshold value.
According to this configuration, in a period in which the power consumption of the heat source system is greater than the first power threshold value, the demand restricting means holds the rotation speed of the water supply means and it is thus possible to prevent an increase in power consumption due to an increase in rotation speed of the water supply means.
In the control device of a heat source system, the demand restricting means may stop an operation of predetermined heat source equipment when the power consumption of the heat source system is greater than a third power threshold value set to a value greater than the first power threshold value and lower than the contracted power.
According to this configuration, when the power consumption of the heat source system is greater than the third power threshold value, the operation of predetermined heat source equipment is stopped. Accordingly, before the power consumption of the heat source system is greater than the contracted power, it is possible to rapidly reduce the power consumption of the heat source system.
In the control device of a heat source system, the demand restricting means may perform a control of reducing power consumption of an electrical instrument of the load equipment in a period in which the power consumption of the heat source system is greater than the first power threshold value.
According to this configuration, in the period in which the power consumption of the heat source system is greater than the first power threshold value, the power consumption of the electrical instrument of the load equipment is reduced by the demand restricting means. Accordingly, it is possible to further reduce the power consumption of the heat source system.
The control device of a heat source system may further include power predicting means for predicting future power consumption from behavior of the power consumption of the heat source system in a predetermined previous period, and the demand restricting means may start the demand restriction when the predicted power consumption after a predetermined period passes from the present time is greater than the first power threshold value.
According to this configuration, future power consumption is predicted from behavior of the power consumption of the heat source system in a predetermined previous period by the power predicting means. The demand restricting means performs the demand restriction when the predicted power consumption after a predetermined period passes from the present time is greater than the first power threshold value. Accordingly, it is possible to preliminarily perform the demand restriction and it is thus possible to prevent the power consumption of the heat source system from reaching the contracted power.
According to a second aspect of the present invention, there is provided a control method of a heat source system having at least one piece of heat source equipment that heats or cools heat source water depending on a set temperature and that supplies the heated or cooled heat source water to load equipment, including: monitoring power consumption of the heat source system; and performing demand restriction by raising or lowering the set temperature so as to decrease power consumption of the heat source equipment when the power consumption of the heat source system is greater than a first power threshold value set to a value lower than that of contracted power.
According to a third aspect of the present invention, there is provided a heat source system including the above-mentioned control device of the heat source system.
According to a fourth aspect of the present invention, there is provided a heat source system having at least one piece of heat source equipment that heats or cools heat source water depending on a set temperature and that supplies the heated or cooled heat source water to load equipment, including: heat source equipment control means that is disposed to correspond to the at least one piece of heat source equipment so as to control the corresponding heat source equipment; and system control means for giving a control command to the heat source equipment control means, wherein the system control means includes power monitoring means for monitoring power consumption of the heat source system, and notification means for giving a demand restriction start command to the heat source equipment control means when the power consumption of the heat source system is greater than a first power threshold value set to a value lower than that of contracted power, and wherein the heat source equipment control means includes demand restricting means for performing demand restriction by raising or lowering the set temperature so as to decrease the power consumption when the demand restriction start command is given.
According to a fifth aspect of the present invention, there is provided a power adjustment network system including: the above-mentioned plural heat source systems; and a central monitor device that is connected to control devices of the heat source systems via a communication medium, wherein the first power threshold value is given from the central monitor device to the control devices of the heat source systems.
According to a sixth aspect of the present invention, there is provided a control device of heat source equipment that heats or cools heat source water depending on a set temperature and that supplies the heated or cooled heat source water to load equipment, including: power monitoring means for monitoring power consumption of the heat source equipment; and demand restricting means for performing demand restriction by raising or lowering the set temperature so as to decrease the power consumption of the heat source equipment when the power consumption of the heat source equipment is greater than a first power threshold value set to a value lower than that of contracted power.

Advantageous Effects of Invention

According to the present invention, it is possible to perform a control so that the power consumption of a heat source system does not exceed contracted power.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically illustrating an overall configuration of a heat source system according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of heat source equipment illustrated in FIG. 1.

FIG. 3 is a diagram schematically illustrating a configuration of a control system of the heat source system according to the first embodiment of the present invention.

FIG. 4 is a functional block diagram illustrating principal elements relevant to a demand restricting function of heat source equipment among functions of a system control device illustrated in FIG. 3.

FIG. 5 is a diagram illustrating a demand restriction of the heat source system according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating an effect of the heat source system according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating another aspect of a demand restricting function in the heat source system according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating demand restriction of a heat source system according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating demand restriction of a heat source system according to a third embodiment of the present invention.

FIG. 10 is a functional block diagram illustrating principal elements relevant to a demand restricting function of heat source equipment among functions of a system control device according to a fifth embodiment of the present invention.

FIG. 11 is a diagram illustrating prediction of power consumption that is performed by a power predicting unit illustrated in FIG. 10.

FIG. 12 is a diagram schematically illustrating a configuration of a power adjustment network system according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Hereinafter, a heat source system, a control device thereof, and a control method thereof according to a first embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram schematically illustrating a configuration of a heat source system 1 according to the first embodiment of the present invention. The heat source system 1 includes load equipment 3, heat source equipment 2 a, 2 b, and 2 c, and a system control device 20. FIG. 1 illustrates an example where three pieces of heat source equipment are installed, but the number of pieces of heat source equipment may be arbitrarily set.
Examples of the load equipment 3 include air-conditioning equipment, hot-water supply equipment, and plant equipment. The respective pieces of heat source equipment 2 a, 2 b, and 2 c heat or cool heat source water on the basis of a set temperature which is set by the system control device 20 and supply the heated or cooled heat source water to the load equipment 3. Here, the heat source water may be a liquid medium other than water.
In this embodiment, for the purpose of convenience of explanation, it is assumed that air-conditioning equipment performing a cooling operation is used as the load equipment 3 and the respective pieces of heat source equipment 2 a, 2 b, and 2 c cool water as the heat source water and supply the cooled water to the load equipment 3.
Cool water pumps (water supply means) 4 a, 4 b, and 4 c that supply heat source water are disposed on the upstream side of the respective heat source equipment 2 a, 2 b, and 2 c in a flow of the cool water. The cool water from a return header 6 is supplied to the pieces of heat source equipment 2 a, 2 b, and 2 c by the cool water pumps 4 a, 4 b, and 4 c. The cool water pumps 4 a, 4 b, and 4 c are driven by an inverter motor (not illustrated). Accordingly, the flow rates are controlled by changing the rotation speed thereof.
A supply header 5 collects cool water obtained by the respective pieces of heat source equipment 2 a, 2 b, and 2 c. The cool water collected in the supply header 5 is supplied to the load equipment 3. The cool water which is used for air-conditioning in the load equipment 3 and of which the temperature is raised is sent to the return header 6. The cool water is branched by the return header 6 and is sent to the pieces of heat source equipment 2 a, 2 b, and 2 c.
A bypass pipe 7 is disposed between the supply header 5 and the return header 6. By adjusting a degree of opening of a bypass valve 8 disposed in the bypass pipe 7, it is possible to adjust an amount of cool water supplied to the load equipment 3.
FIG. 2 illustrates a schematic configuration in which a turbo refrigerator is used as an example of each piece of heat source equipment 2 a, 2 b, and 2 c. In the drawing, only one piece of heat source equipment 2 a among three pieces of heat source equipment arranged in parallel is illustrated for the purpose of easy understanding. The configuration illustrated in FIG. 2 is an example and, for example, a screw refrigerator may be employed instead of the turbo refrigerator. The plural pieces of heat source equipment 2 a, 2 b, and 2 c may employ the same type of heat source equipment or may employ plural types of heat source equipment.
The heat source equipment 2 a includes a turbo compressor 31 that compresses a refrigerant, a condenser 32 that condenses a high-temperature and high pressure gas refrigerant compressed by the turbo compressor 31, a subcooler 33 that supercools the liquid refrigerant condensed by the condenser 32, a high-pressure expansion valve 34 that expands the liquid refrigerant from the subcooler 33, an intermediate cooler 37 that is connected to the high-pressure expansion valve 34 and that is connected to an intermediate stage of the turbo compressor and a low-pressure expansion valve 35, and an evaporator 36 that evaporates the liquid refrigerant expanded by the low-pressure expansion valve 35.
The turbo compressor 31 is a centrifugal two-step compressor and is driven by an electric motor 39 of which the rotation speed is controlled by an inverter 38. The output of the inverter 38 is controlled by a heat source equipment control device 10 a. The turbo compressor 31 may be a fixed-speed compressor of which the rotation speed is fixed. A refrigerant inlet of the turbo compressor 31 is provided with an inlet guide vane (hereinafter, referred to as “IGV”) 40 that controls an inlet refrigerant flow rate and it is thus possible to control the capacity of the heat source equipment 2 a.
The condenser 32 is provided with a pressure sensor 51 for measuring a condensed refrigerant pressure Pc. The output of the pressure sensor 51 is transmitted to the heat source equipment control device 10 a.
The subcooler 33 is disposed on the downstream side of the condenser 32 in the refrigerant flow so as to supercool the condensed refrigerant. A temperature sensor for measuring the temperature Ts of the supercooled refrigerant is disposed just on the downstream side of the subcooler 33 in the refrigerant flow.
A cooling heat-transfer tube 41 for cooling the condenser 32 and the subcooler 33 is inserted into the condenser and the subcooler. A coolant flow rate F2 is measured by a flowmeter 54, a coolant outlet temperature Tcout is measured by a temperature sensor 55, and a coolant inlet temperature Tcin is measured by a temperature sensor 56. The heat of the coolant is exhausted in a cooling tower (not illustrated) to the outside and then the coolant is guided to the condenser 32 and the subcooler 33 again.
The intermediate cooler 37 is provided with a pressure sensor 57 for measuring an intermediate pressure Pm. The evaporator 36 is provided with a pressure sensor 58 for measuring an evaporating pressure Pe. Cool water of a rated temperature (for example, 7° C.) is obtained by causing the evaporator 36 to absorb the heat thereof. A coolant heat-transfer tube 42 for cooling the cool water supplied to an external equipment 3 (see FIG. 1) is inserted into the evaporator 36. A cool water flow rate F1 is measured by a flowmeter 59, a cool water outlet temperature Tout is measured by a temperature sensor 60, and a cool water inlet temperature Tin is measured by a temperature sensor 61.
A hot gas bypass pipe 43 is disposed between a gas phase unit of the condenser 32 and a gas phase unit of the evaporator 36. A hot gas bypass valve 44 for controlling a flow rate of the refrigerant flowing in the hot gas bypass pipe 43 is disposed therein. By adjusting the hot gas bypass flow rate through the use of the hot gas bypass valve 44, it is possible to control capability of a very small region of which a control by the IGV 40 is not sufficient.
In the heat source equipment 2 a illustrated in FIG. 2, the condenser 32 and the subcooler 33 are provided and heat exchange between the cooled coolant and the refrigerant is carried out by exhausting the heat to the outside in the cooling tower, but the present invention is not limited to this configuration. For example, an air heat exchanger may be provided instead of the condenser 32 and the subcooler 33 and heat exchange between external air and the refrigerant may be carried out by the air heat exchanger.
FIG. 3 is a diagram schematically illustrating a configuration of a control system of the heat source system 1 illustrated in FIG. 1. The heat source equipment control devices 10 a, 10 b, and 10 c which are the control devices of the respective pieces of heat source equipment 2 a, 2 b, and 2 c are connected to the system control device 20 via a communication medium 21 so as to interactively communicate with each other as illustrated in FIG. 3. The system control device 20 is a control device for controlling the whole heat source system, and has a demand restricting function of restricting demands so that the power consumption of the whole system is not greater than the contracted power and a piece number control function of controlling the number of pieces of heat source equipment 2 a, 2 b, and 2 c which will be activated for a request load of the load equipment 3.
The system control device 20 and the heat source equipment control devices 10 a, 10 b, and 10 c are embodied, for example, by computers and each include a central processing unit (CPU), a main storage device such as a random access memory (RAM), an auxiliary storage device, and a communication device that transmits and receives information by communication with external devices.
The auxiliary storage device is a computer-readable recording medium and examples thereof include a magnetic disk, a magneto-optical disc, a CD-ROM, a DVD-ROM, and a semiconductor memory. Various programs are stored in the auxiliary storage device and various processes are carried out by causing the CPU to read the programs from the auxiliary storage device to the main storage device.
FIG. 4 is a functional block diagram illustrating primary elements relevant to the demand restricting function among the functions of the system control device 20.
As illustrated in FIG. 4, the system control device 20 includes a storage unit 22, a power monitoring unit 23, and a demand restricting unit 24 as principal elements.
The storage unit 22 stores a first power threshold value set to a value lower than the contracted power, a second power threshold value set to a value equal to or less than the first power threshold value, and a reference set temperature (for example, 5° C.). The reference set temperature is a set temperature as a reference of the water supply temperature of the cool water supplied from the respective pieces of heat source equipment 2 a, 2 b, and 2 c to the load equipment 3.
The power monitoring unit 23 monitors the power consumption of the heat source system (hereinafter, referred to as “system power consumption”). For example, a multi-meter is attached to a main power supply system of the heat source system and the system power consumption is monitored by inputting the measured value to the system control device 20.
The demand restricting unit 24 performs demand restriction so that the system power consumption monitored by the power monitoring unit 23 is not greater than the contracted power. For example, when the system power consumption is greater than the first power threshold value stored in the storage unit 22, the demand restricting unit 24 performs the demand restriction by raising the set temperature of the water supply temperature. In this case, when the system power consumption is greater than the first power threshold value, the set temperature which is the target value of the water supply temperature is changed so as to decrease the power consumption. Accordingly, it is possible to reduce a head differential pressure of the compressor and thus to reduce the power of the compressor. As a result, it is possible to suppress the power consumption of the pieces of heat source equipment 2 a, 2 b, and 2 c.
When the system power consumption is less than the second power threshold value stored in the storage unit 22 at the time of performing the demand restriction, the demand restricting unit 24 lowers the set temperature. Accordingly, it is possible to cause the water supply temperature of the cool water supplied to the load equipment 3 to approach the reference set temperature.
The demand restriction of the heat source system 1 according to this embodiment having the above-mentioned configuration will be described below with reference to FIG. 5.
For example, at time t1 in FIG. 5, when the system power consumption is greater than the first power threshold value, the demand restricting unit 24 of the system control device 20 raises the set temperature at a predetermined rate. The changed set temperature is transmitted from the system control device 20 to the heat source equipment control devices 10 a, 10 b, and 10 c and each piece of heat source equipment 2 a, 2 b, and 2 c is controlled on the basis of the changed set temperature. Accordingly, the system power consumption is changed so as to slowly decrease with a delay more or less (see time t1 to time t2 in FIG. 5). At time t2, when the system power consumption is less than the second power threshold value, the demand restricting unit 24 of the system control device 20 lowers the set temperature at a predetermined rate. As described above, the changed set temperature is transmitted from the system control device 20 to the heat source equipment control devices 10 a, 10 b, and 10 c and each piece of heat source equipment 2 a, 2 b, and 2 c is controlled on the basis of the changed set temperature.
By lowering the set temperature, the power consumption of the respective pieces of heat source equipment 2 a, 2 b, and 2 c increases. At time t3, when the system power consumption is greater than the first power threshold value again, the demand restricting unit 24 of the system control device 20 raises the set temperature at a predetermined rate. As a result, the system power consumption slowly decreases. At time t4, when the system power consumption is less than the second power threshold value, the demand restricting unit 24 of the system control device 20 lowers the set temperature at a predetermined rate. When the set temperature reaches the reference set temperature, the reference set temperature is maintained.
In FIG. 5, the set temperature is slowly raised and lowered at the predetermined rate, but the method of raising and lowering the set temperature is not limited to this example. For example, the set temperature may be slowly raised and lowered in a steplike manner.
In FIG. 5, the first power threshold value and the second power threshold value are set to different values, but the first power threshold value and the second power threshold value may be set to the same value.
As described above, in the heat source system, the control device thereof, and the control method thereof according to this embodiment, the system power consumption is monitored and the set temperature of the cool water in the heat source equipment is raised when the system power consumption is greater than the first power threshold value. Accordingly, it is possible to reduce the head differential pressure of the compressor in each heat source equipment and thus to suppress the power consumption of each heat source equipment. As a result, it is possible to lower the system power consumption and to prevent the system power consumption from exceeding the contracted power.
Particularly, as described above, by employing the method of raising the set temperature of the cool water as means for reducing the power consumption of the respective pieces of heat source equipment, it is possible to effectively reduce the power consumption of the respective heat source equipment as illustrated in FIG. 6.
For example, when the horizontal axis represents a load factor and the vertical axis represents the power consumption of the heat source equipment as illustrated in FIG. 6, the load-power consumption characteristic at a designed operating point (for example, the coolant outlet temperature Tcout=37° C. and the cool water outlet temperature Tout=5° C.) exhibits a curve expressed by a thin line. On the contrary, when the set temperature of the cool water is raised to 7° C. (for example, the coolant outlet temperature Tcout=37° C. and the cool water outlet temperature Tout=7° C.), the head differential pressure of the compressor decreases, the operating point is changed, and the load-power consumption characteristic exhibits a curve expressed by a thick line. That is, by decreasing the head differential pressure, it is possible to move the load-power consumption characteristic so as to decrease the power consumption.
When the set temperature is raised from 5° C. to 7° C., the load factor is changed. That is, when the cool water outlet temperature at a load factor of 100% is 5° C. and the set temperature (the cool water outlet temperature) is changed to 7° C., the load factor decreases from 100% to 60%. Accordingly, as illustrated in FIG. 6, it is possible to further reduce the power consumption.
In this way, by changing the set temperature of the cool water, it is possible to achieve both a power consumption decreasing effect based on the head differential pressure of the compressor and a power consumption decreasing effect based on a decrease in load factor, thereby effectively reducing the power consumption.
It has been described above that cool water as heat source water is cooled and is then supplied to the load equipment 3, but water may be heated by each piece of heat source equipment 2 a, 2 b, and 2 c and then may be supplied to the load equipment 3. In this case, the demand restricting unit 24 lowers the set temperature when the system power consumption is greater than the first power threshold value, and raises the set temperature when the system power consumption is less than the second power threshold value. Accordingly, it is possible to achieve the same effect.

Another Aspect 1

In operation of the heat source system 1, priority may be given to the supply of cool water of a predetermined temperature or lower to the load equipment 3 rather than the control of the power consumption so as not to be greater than the contracted power. For example, in a department store or the like, when the temperature of cool water excessively rises, the indoor temperature rises to cause clients to feel unpleasant. In consideration of this case, an aspect in which an upper limit value of the set temperature at the time of performing the demand restriction is stored in advance in the storage unit 22 and the set temperature is maintained at the upper limit value when the set temperature reaches the upper limit value may be employed. In this way, by setting the upper limit value, it is possible to prevent the temperature of cool water from rising to be higher than the upper limit value.
When heating is performed by the heat source equipment, a lower limit value of the set temperature may be set to prevent the set temperature from falling to be lower than the lower limit value.

Another Aspect 2

As illustrated in FIG. 7, a demand restriction stopping unit 25 for stopping the demand restriction may be provided and the demand restriction may not be performed when the demand restriction stopping unit 25 operates. The stop and the release of the stop of the demand restriction by the demand restriction stopping unit may be set, for example, on the basis of input information input from an operator.

Second Embodiment

A heat source system, a control device thereof, and a control method thereof according to a second embodiment of the present invention will be described below with reference to the accompanying drawings.
In the above-mentioned embodiment, the system control device 20 performs the demand restriction by raising the set temperature of cool water. In this way, when the set temperature of cool water is raised, an amount of heat in the load equipment 3 may be deficient. In this case, this deficiency in the amount of heat may be solved by increasing the flow rate of cool water. When an operation of increasing the flow rate of cool water is performed by the load equipment 3 side, the rotation speeds of the cool water pumps provided to correspond to the respective pieces of heat source equipment 2 a, 2 b, and 2 c increase and the demand restriction based on the set temperature of cool water may not effectively work.
Therefore, in this embodiment, in a period in which the demand restriction is carried out, the rotation speed of the cool water pumps is held to prevent an increase in power consumption in the cool water pump.
Specifically, the demand restricting unit of the system control device 20 holds a frequency command of the cool water pumps in a period in which the system power consumption is greater than the first power threshold value and less than the second power threshold value as illustrated in FIG. 8. Accordingly, it is possible to prevent an increase in power of the cool water pumps 4 a, 4 b, and 4 c due to an increase in the flow rate of cool water on the load equipment 3 side and thus to effectively reflect the demand restriction based on the change in the set temperature in the system power consumption.

Third Embodiment

A heat source system, a control device thereof, and a control method thereof according to a third embodiment of the present invention will be described below with reference to the accompanying drawings.
Even when the demand restriction according to the first or second embodiment is carried out, the system power consumption may be finally greater than the contracted power. In order to cope with this case, in this embodiment, a third power threshold value set to a value greater than the first power threshold value and less than the contracted power may be additionally stored in the storage unit 22 and the demand restricting unit 24 may forcibly stop at least one of the pieces of heat source equipment in operation when the system power consumption is greater than the third power threshold value, as illustrated in FIG. 9.
Accordingly, even when the demand restriction of raising the set temperature is performed by the demand restricting unit 24 but the system power consumption subsequently increases, the operation of one piece of heat source equipment is forcibly stopped before the power consumption reaches the contracted power. It is possible to rapidly lower the system power consumption and to prevent the system power consumption from being greater than the contracted power.
In this case, the demand restricting unit 24 may restart the heat source equipment which has been forcibly stopped when the system power consumption is less than the second power threshold value.

Fourth Embodiment

A heat source system, a control device thereof, and a control method thereof according to a fourth embodiment of the present invention will be described below with reference to the accompanying drawings.
A heat source system according to this embodiment is different from the heat source systems according to the above-mentioned embodiments, in that the demand restricting unit 24 of the system control device 20 performs the demand restriction according to any one of the first to third embodiments and the control of decreasing the power of various electrical instruments (not illustrated) of the load equipment 3 when the system power consumption is greater than the first power threshold value.
For example, when the load equipment 3 is an air-conditioning facility, the volume of air blown indoor is changed by changing the rotation speed of a fan. In this way, when the load equipment 3 is provided with an electrical instrument controlled by an inverter, the demand restricting unit 24 achieves the further suppression of the system power consumption by changing the set temperature in the heat source equipment and decreasing the frequency of the electrical instrument in the load equipment 3.
Accordingly, it is possible to rapidly reduce the system power consumption and thus to reduce the possibility that the system power consumption will be greater than the contracted power.

Fifth Embodiment

A heat source system, a control device thereof, and a control method thereof according to a fifth embodiment of the present invention will be described below with reference to the accompanying drawings.
In the first to fourth embodiments, the demand restriction is carried out by comparing the current system power consumption with the power threshold values. In this case, a certain time is required until the system power consumption is reduced after the demand restriction is started. Accordingly, even when the demand restriction is carried out, there is a possibility that the system power consumption will be greater than the contracted power in some cases.
Therefore, in this embodiment, the system control device is provided with a power predicting unit 26, as illustrated in FIG. 10. The power predicting unit 26 predicts future power consumption from behavior of the power consumption of the heat source system in a predetermined period T1 previous to the present time as illustrated in FIG. 11. The demand restricting unit 24 starts the demand restriction when the predicted power consumption after a predetermined period T2 elapses from the present time is greater than the first power threshold value.
Here, the predetermined period T1 is a period that can be arbitrarily determined and is set to, for example, 30 minutes to 1 hour. The predetermined period T2 is set to at least a time longer than the time delay until the system power consumption starts its decrease after the demand restriction is started.
In this way, since the future system power consumption is predicted from the behavior of the previous system power consumption and it is determined whether the demand restriction should be started on the basis of the predicted system power consumption, it is possible to effectively prevent the system power consumption from being greater than the contracted power.
The power predicting method in the power predicting unit 26 can employ a known prediction technique and, for example, the future power is predicted from a change rate of the system power consumption in a predetermined previous period.
In the above-mentioned embodiments, the system control device 20 collectively performs the demand restriction of the respective pieces of heat source equipment, but the heat source equipment control devices 10 a, 10 b, and 10 c may be provided with the demand restriction functions so as to perform the demand restriction for each piece of heat source equipment.
In this case, the first power threshold value, the second power threshold value, and the like are set, for example, on the basis of limit power of the respective pieces of heat source equipment to which the contracted power of the whole system is distributed, and the above-mentioned demand restriction is carried out on the basis of the relationships between the power consumption of the respective pieces of heat source equipment and the first power threshold value and the second power threshold value. The power consumption of the respective pieces of heat source equipment can be detected by attaching a multi-meter to the power supply system of the respective pieces of heat source equipment.
In this way, by only providing the demand restricting function of the system control device 20 to the respective heat source equipment control devices, it is possible to suppress the power consumption.
In a modification example, the system control device 20 may perform monitoring of the power consumption. That is, the system control device 20 may monitor the system power consumption and may give a demand restriction start command for starting the demand restriction to the respective heat source equipment control devices when the system power consumption is greater than the first power threshold value. In this way, the system control device may compare the system power consumption with the threshold values and may notify the comparison result to the respective heat source equipment control devices so as to carry out the demand restriction.
When the demand restriction is carried out for each piece of heat source equipment, the pieces of heat source equipment may have different change rates of the set temperature.
A power adjustment network system according to an embodiment of the present invention will be described below.
As illustrated in FIG. 12, the power adjustment network system according to this embodiment includes the system control devices 20 a, 20 b, and 20 c of the plural heat source systems according to any one of the above-mentioned embodiments and a central monitor device 50 that is connected to the system control devices 20 a, 20 b, and 20 c of the heat source systems via a communication medium 51.
The central monitor device 50 acquires the system power consumption from the respective system control devices 20 a, 20 b, and 20 c of the heat source systems, determines the first power threshold value on the basis of the acquired information and the contracted power, and transmits the first power threshold value to the respective system control devices 20. For example, when the demand restriction is carried out or a heat source system in which the demand restriction is about to be started and a heat source system in which there is a margin until the demand restriction will be started, that is, in which a difference between the system power consumption and the first power threshold value is equal to or greater than a predetermined value, are present, the central monitor device 50 increases the first power threshold value of the former heat source system and decreases the first power threshold value of the latter heat source system. In this way, by comparing the system power consumption values of the heat source systems and adjusting the first power threshold value of the heat source systems, it is possible to flexibly adjust power.

REFERENCE SIGNS LIST

- 1: heat source system
- 2 a, 2 b, 2 c: heat source equipment
- 3: load equipment
- 4 a, 4 b, 4 c: cool water pump
- 5: supply header
- 6: return header
- 10 a, 10 b, 10 c: heat source equipment control device
- 20: system control device
- 21: communication medium
- 22: storage unit
- 23: power monitoring unit
- 24: demand restricting unit
- 25: demand restriction stopping unit
- 26: power predicting unit
- 31: turbo compressor
- 38: inverter
- 50: central monitor device

Claims

1. A control device of a heat source system having at least one piece of heat source equipment that heats or cools heat source water depending on a set temperature and that supplies the heated or cooled heat source water to load equipment, comprising:

power monitoring means for monitoring power consumption of the heat source system; and

demand restricting means for performing demand restriction by raising or lowering the set temperature so as to decrease power consumption of the heat source equipment when the power consumption of the heat source system is greater than a first power threshold value set to a value lower than that of contracted power.

2. The control device of a heat source system according to claim 1, wherein the demand restricting means lowers or raises the set temperature so as to increase the power consumption of the heat source equipment when the power consumption of the heat source system is less than a second power threshold value set to a value equal to or less than the first power threshold value, and maintains the set temperature when a current set temperature reaches a predetermined reference set temperature.

3. The control device of a heat source system according to claim 1, wherein the demand restricting means lowers the set temperature so as not to be less than a predetermined lower limit value when the heat source equipment heats the heat source water, and raises the set temperature so as not to be greater than a predetermined upper limit value when the heat source equipment cools the heat source water.

4. The control device of a heat source system according to claim 1, further comprising demand restriction stopping means for stopping the demand restriction by the demand restricting means.

5. The control device of a heat source system according to claim 1, further comprising electrical water supply means for adjusting a flow rate of the heat source water supplied from an external apparatus to the heat source equipment,

wherein the demand restricting means holds a rotation speed of the water supply means in a period in which the power consumption of the heat source system is greater than the first power threshold value.

6. The control device of a heat source system according to claim 1, wherein the demand restricting means stops an operation of predetermined heat source equipment when the power consumption of the heat source system is greater than a third power threshold value set to a value greater than the first power threshold value and lower than the contracted power.

7. The control device of a heat source system according to claim 1, wherein the demand restricting means performs a control of reducing power consumption of an electrical instrument of the load equipment in a period in which the power consumption of the heat source system is greater than the first power threshold value.

8. The control device of a heat source system according to claim 1, further comprising power predicting means for predicting future power consumption from behavior of the power consumption of the heat source system in a predetermined previous period,

wherein the demand restricting means starts the demand restriction when the predicted power consumption after a predetermined period passes from the present time is greater than the first power threshold value.

9. A control method of a heat source system having at least one piece of heat source equipment that heats or cools heat source water depending on a set temperature and that supplies the heated or cooled heat source water to load equipment, comprising:

monitoring power consumption of the heat source system; and

performing demand restriction by raising or lowering the set temperature so as to decrease power consumption of the heat source equipment when the power consumption of the heat source system is greater than a first power threshold value set to a value lower than that of contracted power.

10. A heat source system comprising the control device of a heat source system according to claim 1.

11. A heat source system having at least one piece of heat source equipment that heats or cools heat source water depending on a set temperature and that supplies the heated or cooled heat source water to load equipment, comprising:

heat source equipment control means that is disposed to correspond to the at least one piece of heat source equipment so as to control the corresponding heat source equipment; and

system control means for giving a control command to the heat source equipment control means,

wherein the system control means includes

power monitoring means for monitoring power consumption of the heat source system, and

notification means for giving a demand restriction start command to the heat source equipment control means when the power consumption of the heat source system is greater than a first power threshold value set to a value lower than that of contracted power, and

wherein the heat source equipment control means includes demand restricting means for performing demand restriction by raising or lowering the set temperature so as to decrease the power consumption when the demand restriction start command is given.

12. A power adjustment network system comprising:

a plurality of heat source systems according to claim 10; and

a central monitor device that is connected to control devices of the heat source systems via communication medium,

wherein the first power threshold value is given from the central monitor device to the control devices of the heat source systems.

13. A control device of heat source equipment that heats or cools heat source water depending on a set temperature and that supplies the heated or cooled heat source water to load equipment, comprising:

power monitoring means for monitoring power consumption of the heat source equipment; and

demand restricting means for performing demand restriction by raising or lowering the set temperature so as to decrease the power consumption of the heat source equipment when the power consumption of the heat source equipment is greater than a first power threshold value set to a value lower than that of contracted power.