CN117515786A - Adding and subtracting machine control method and system of refrigerating unit - Google Patents
Adding and subtracting machine control method and system of refrigerating unit Download PDFInfo
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- CN117515786A CN117515786A CN202311344359.6A CN202311344359A CN117515786A CN 117515786 A CN117515786 A CN 117515786A CN 202311344359 A CN202311344359 A CN 202311344359A CN 117515786 A CN117515786 A CN 117515786A
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- 238000000034 method Methods 0.000 title claims abstract description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 239
- 238000011217 control strategy Methods 0.000 claims abstract description 16
- 238000005057 refrigeration Methods 0.000 claims description 27
- 230000007423 decrease Effects 0.000 claims description 10
- 238000001514 detection method Methods 0.000 claims description 10
- 230000001105 regulatory effect Effects 0.000 abstract description 2
- 238000001816 cooling Methods 0.000 description 8
- 239000000498 cooling water Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F11/46—Improving electric energy efficiency or saving
- F24F11/47—Responding to energy costs
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
- F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
- F24F11/85—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using variable-flow pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/89—Arrangement or mounting of control or safety devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F2140/00—Control inputs relating to system states
- F24F2140/20—Heat-exchange fluid temperature
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F2140/00—Control inputs relating to system states
- F24F2140/50—Load
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/18—Optimization, e.g. high integration of refrigeration components
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The invention provides an add-subtract machine control method and system of a refrigerating unit, wherein the method comprises the following steps: the water chiller comprises water chiller units, wherein a first temperature sensor is arranged at a water outlet of each water chiller unit, and a second temperature sensor is arranged at a water return position; comprising the following steps: and (3) a water chiller loading control strategy: judging whether to add the machine according to the current load, and starting another water chilling unit when the machine needs to be started; and (3) a load shedding control strategy of the water chilling unit: when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the return water temperature is detected to be reduced according to the second temperature sensor, the water chilling unit firstly reduces the refrigerating load of the water chilling unit, when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of a single water chilling unit, one group of water chilling units is closed, the highest-efficiency water pump number is started according to the load demand, the safe running basis of a host is met, and meanwhile, the rotating speed of the water pump motor is regulated, so that the aim of saving energy is achieved.
Description
Technical Field
The invention relates to an add-subtract machine control method and system of a refrigerating unit.
Background
The existing refrigeration station calculates the cold load according to the water supply/return temperature of a refrigeration water supply/return water main pipe of the water chilling unit and the total water supply quantity of the refrigeration station, and decides to start the water chilling unit and the corresponding primary pump number according to the change of the cold load, so that the water chilling unit works in an optimal state, thereby achieving the purpose of energy conservation; in addition, when the equipment is started, the running time is accumulated every time, the working/standby switching is automatically implemented to achieve the balance of the running time, the number of the units which are put into is automatically controlled according to the change of the cold load, the input time and sequence of the host are selected, and the constant flow running of the water chilling unit is ensured.
However, the group control of the units cannot be guaranteed effectively by the above requirements alone. In actual operation, the unit can not realize the control of adjusting the number of the water chilling units according to the actual cooling load. For example, the cold load of the water chiller set is opened in actual conditions and can not meet the end requirement of an air conditioner, at the moment, the temperature of the chilled water is increased due to the insufficient refrigeration load, the water supply temperature of the water chiller set exceeds a set value, the heat exchange efficiency of the chilled water and the air in the fan coil is continuously reduced, the temperature difference of the supplied water and the returned water is reduced, the water supply flow is not changed, and the calculated cold load is reduced. This is obviously not the really required cooling load. In actual operation, the water temperature of the water separator reaches 16 ℃, the water temperature of the water collector is 16.3 ℃, the load of the cooling capacity calculation is small, and the number of water chilling units is not increased in system control.
In addition, if the control strategy requires 'measuring the temperature difference of the water supply/return water and the water flow rate of each loop of the water chilling unit', the load of each loop is calculated. And when the load is greater than 80% of one unit, the second unit operates. Similarly, under a certain working condition (this is also common), the cooling capacity of the cooling machine is limited to 70% of the maximum cooling capacity due to poor cooling effect of the cooling water loop. According to the control strategy, only one chiller can be started forever.
Disclosure of Invention
The invention aims to solve the technical problem of providing an add-subtract machine control method and system of a refrigerating unit, which are used for meeting the safety operation basis of a host machine and simultaneously adjusting the rotating speed of a water pump motor so as to achieve the aim of saving energy by starting the number of water pumps with the highest efficiency according to the load requirement.
In a first aspect, the invention provides an add-subtract machine control method of a refrigerating unit, which comprises a water chilling unit, wherein a first temperature sensor is arranged at a water outlet of each water chilling unit, and a second temperature sensor is arranged at a water return position; comprising the following steps:
and (3) a water chiller loading control strategy:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the front chiller is kept to be more than or equal to the total load of the first set value percent, the second chiller is started at the moment;
and (3) a load shedding control strategy of the water chilling unit:
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the temperature of the backwater is reduced detected by the second temperature sensor, and when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of a single water chilling unit, one group of water chilling units is closed.
Further, the water chiller loading control strategy is further specifically:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the previous chiller is kept to be more than or equal to the total load of the first set value percent, and when K1 is more than the first threshold, the second chiller is started at the moment;
wherein: k1 = (CHWT-chwt.stp)/0.005; CHWT is the outlet water temperature; chwt.stp is the outlet water temperature set point.
Further, the load shedding control strategy of the water chiller further specifically comprises the following steps:
when only one group of water chilling units operates, no load shedding judgment is carried out; when the water chilling unit is more than or equal to the two groups of water chilling units, load shedding judgment is carried out;
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the return water temperature is detected to be reduced by the second temperature sensor, when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of the single water chilling unit, if the reduced load is smaller than a second set value and K2 is larger than a second threshold value, a group of refrigerating units are closed;
wherein: k2 = (chet.stp-CHET)/0.005; CHET is the return water temperature; chet.stp is the set point for the return water temperature.
Further, the closing of a refrigerating unit is specifically: the refrigeration unit with the longest continuous operation time is turned off.
In a second aspect, the invention provides an add-subtract machine control system of a refrigerating unit, which comprises a water chilling unit, wherein a first temperature sensor is arranged at a water outlet of each group of water chilling unit, and a second temperature sensor is arranged at a water return position; comprising the following steps:
the water chiller loading control module:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the front chiller is kept to be more than or equal to the total load of the first set value percent, the second chiller is started at the moment;
and the water chilling unit load shedding control module is used for:
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the temperature of the backwater is reduced detected by the second temperature sensor, and when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of a single water chilling unit, one group of water chilling units is closed.
Further, the water chiller loading control module is further specifically:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the previous chiller is kept to be more than or equal to the total load of the first set value percent, and when K1 is more than the first threshold, the second chiller is started at the moment;
wherein: k1 = (CHWT-chwt.stp)/0.005; CHWT is the outlet water temperature; chwt.stp is the outlet water temperature set point.
Further, the water chilling unit load shedding control module is further specifically:
when only one group of water chilling units operates, no load shedding judgment is carried out; when the water chilling unit is more than or equal to the two groups of water chilling units, load shedding judgment is carried out;
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the return water temperature is detected to be reduced by the second temperature sensor, when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of the single water chilling unit, if the reduced load is smaller than a second set value and K2 is larger than a second threshold value, a group of refrigerating units are closed;
wherein: k2 = (chet.stp-CHET)/0.005; CHET is the return water temperature; chet.stp is the set point for the return water temperature.
Further, the closing of a refrigerating unit is specifically: the refrigeration unit with the longest continuous operation time is turned off.
One or more technical solutions provided in the embodiments of the present invention at least have the following technical effects or advantages:
the number of the units is optimized, the units are ensured to operate in the highest efficiency interval, energy is saved, and operation cost is saved. According to the building load demand, the highest-efficiency water pump number is started, the safe operation basis of the host is met, and the rotating speed of the water pump motor is regulated, so that the aim of saving energy is fulfilled.
The running life of the unit equipment is prolonged; the operation time of each device is accumulated, and the operation/standby switching is automatically implemented, so that the operation time of the device is averaged, the service life of a unit is prolonged, and the utilization efficiency of the device is improved.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present invention more readily apparent.
Drawings
The invention will be further described with reference to examples of embodiments with reference to the accompanying drawings.
FIG. 1 is a flow chart of a method according to a first embodiment of the invention;
fig. 2 is a schematic diagram of a system in a second embodiment of the present invention.
Detailed Description
According to the technical scheme in the embodiment of the application, the overall thought is as follows:
the automatic monitoring system for the water chilling unit is characterized in that a corresponding input and output module is added on the basis of the automatic monitoring system for the water chilling unit, and the corresponding temperature sensor, the pressure transmitter and other sensors are connected, and the cooling water pump, the chilled water pump and the cooling tower can be automatically monitored and controlled by controlling the related electric valve and the electric switch.
a, a water chiller loading control strategy:
when the load at the tail end of the system is increased, the corresponding pressure difference at the tail end is reduced, the total backwater temperature is increased, the evaporation temperature of the water chilling unit is increased, the unit can lock and set the water outlet temperature to 7 ℃, therefore, the unit uploads the refrigeration load according to the capacity of self load adjustment, when the current load of the water chilling unit is increased to 97% of the total load (adjustable according to actual conditions), and the water chilling unit can not stabilize the water outlet temperature, the group control system of the water chilling unit considers that the running unit can not meet the tail end requirement, the adding delay of another unit is required to be started for 5 minutes (adjustable according to actual conditions), after the starting delay period, if the current load is more than or equal to 97% of the total load, and K1 is more than or equal to 200, the full load operation of the water chilling unit is insufficient to meet the system load value, and the water outlet temperature of chilled water can not be stabilized on the water outlet temperature set value, so that the auxiliary equipment of the second water chilling unit is operated in sequence, and after a certain time, the second water chilling unit is started rapidly.
Wherein: k1 = (CHWT-CHWT. Stp)/0.005
CHWT-chilled Water outlet temperature
CHWT. STP-chilled Water outlet temperature set point (7 ℃ C.)
The outlet water temperature of the chilled water is set to be 7 ℃, and when K1 is more than or equal to 200 and the current load of the water chilling unit is more than or equal to 97%, the second water chilling unit is automatically started.
b load shedding control strategy for water chilling unit
When the system load becomes smaller, the pressure difference at the tail end is increased, the total backwater temperature is correspondingly reduced, and the evaporation temperature is also reduced. Firstly, the refrigerating capacity of the unit can be reduced to adapt to the change, when the reduced refrigerating capacity of the operated unit reaches the maximum capacity of a single unit, the operation unit can be reduced, and the rest operation water chilling unit can be operated under the working condition of higher load (the unit can have better energy efficiency ratio under higher load as known by the characteristics of the former unit). Under different running numbers, the load of the unit is judged to be different. If the reduced load is less than the load set value of the machine and K2 is more than 200, the machine set can be reduced to meet the system load value, and the chilled water return water temperature cannot be stabilized on the return water temperature set value, so that the machine set which needs to be stopped is selected to be closed, and auxiliary equipment is closed after a certain time.
Wherein: k2 = (chet.stp-CHET)/0.005
CHET-chilled Water Return temperature
CHET.STP-setting value of chilled Water return temperature (12 ℃ C.)
The return water temperature value of the chilled water is set to be 12 ℃, and when K2 is more than or equal to 200, and the reduced load of the water chilling unit is less than the load set value of the machine, one running unit is stopped.
According to real-time data measured by a temperature sensor and a flowmeter on the water chiller, the cold energy demand value can be calculated according to the following formula:
Q＝c m(T1-T2)
wherein Q is total cold demand (Kcal/h);
c is the specific heat of water (Kcal/Kg ℃);
m is the flow rate (Kg/h) of chilled water;
t1 is the return water temperature (DEG C) of chilled water;
t2 is the chilled water supply temperature (. Degree. C.).
Example 1
As shown in fig. 1, the embodiment provides an add-subtract machine control method of a refrigerating unit, which comprises a water chilling unit, wherein a first temperature sensor is arranged at a water outlet of each water chilling unit, and a second temperature sensor is arranged at a water return position; comprising the following steps:
and (3) a water chiller loading control strategy:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the previous chiller is kept to be more than or equal to the total load of the first set value percent, and when K1 is more than the first threshold, the second chiller is started at the moment;
wherein: k1 = (CHWT-chwt.stp)/0.005; CHWT is the outlet water temperature; chwt.stp is the outlet water temperature set point.
And (3) a load shedding control strategy of the water chilling unit:
when only one group of water chilling units operates, no load shedding judgment is carried out; when the water chilling unit is more than or equal to the two groups of water chilling units, load shedding judgment is carried out;
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the return water temperature is detected to be reduced by the second temperature sensor, when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of the single water chilling unit, if the reduced load is smaller than a second set value and K2 is larger than a second threshold value, a group of refrigerating units are closed;
wherein: k2 = (chet.stp-CHET)/0.005; CHET is the return water temperature; chet.stp is the set point for return water temperature, and the closing of a refrigeration unit specifically is: the refrigeration unit with the longest continuous operation time is turned off.
Based on the same inventive concept, the present application also provides a system corresponding to the method in the first embodiment, and details of the second embodiment are described in the following.
Example two
As shown in fig. 2, in this embodiment, an add-subtract machine control system of a refrigeration unit is provided, including a water chilling unit, a first temperature sensor is disposed at a water outlet of each group of the water chilling unit, and a second temperature sensor is disposed at a water return position; comprising the following steps:
the water chiller loading control module: when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the previous chiller is kept to be more than or equal to the total load of the first set value percent, and when K1 is more than the first threshold, the second chiller is started at the moment;
wherein: k1 = (CHWT-chwt.stp)/0.005; CHWT is the outlet water temperature; chwt.stp is the outlet water temperature set point.
And the water chilling unit load shedding control module is used for: when only one group of water chilling units operates, no load shedding judgment is carried out; when the water chilling unit is more than or equal to the two groups of water chilling units, load shedding judgment is carried out;
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the return water temperature is detected to be reduced by the second temperature sensor, when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of the single water chilling unit, if the reduced load is smaller than a second set value and K2 is larger than a second threshold value, a group of refrigerating units are closed;
wherein: k2 = (chet.stp-CHET)/0.005; CHET is the return water temperature; chet.stp is the set point for return water temperature, and the closing of a refrigeration unit specifically is: the refrigeration unit with the longest continuous operation time is turned off.
Since the system described in the second embodiment of the present invention is a system for implementing the method in the first embodiment of the present invention, based on the method described in the first embodiment of the present invention, a person skilled in the art can understand the specific structure and the modification of the system, and therefore, the description thereof is omitted herein. All systems used in the method according to the first embodiment of the present invention are within the scope of the present invention.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that the specific embodiments described are illustrative only and not intended to limit the scope of the invention, and that equivalent modifications and variations of the invention in light of the spirit of the invention will be covered by the claims of the present invention.
Claims (8)
1. The control method of the addition and subtraction machine of the refrigerating unit comprises a water chilling unit and is characterized in that a first temperature sensor is arranged at a water outlet of each group of the water chilling unit, and a second temperature sensor is arranged at a water return position; comprising the following steps:
and (3) a water chiller loading control strategy:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the front chiller is kept to be more than or equal to the total load of the first set value percent, the second chiller is started at the moment;
and (3) a load shedding control strategy of the water chilling unit:
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the temperature of the backwater is reduced detected by the second temperature sensor, and when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of a single water chilling unit, one group of water chilling units is closed.
2. The method for controlling the addition and subtraction of the refrigerating unit according to claim 1, wherein the loading control strategy of the water chilling unit is further specifically:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the previous chiller is kept to be more than or equal to the total load of the first set value percent, and when K1 is more than the first threshold, the second chiller is started at the moment;
wherein: k1 = (CHWT-chwt.stp)/0.005; CHWT is the outlet water temperature; chwt.stp is the outlet water temperature set point.
3. The method for controlling the addition and subtraction of the refrigerating unit according to claim 1, wherein the load shedding control strategy of the water chiller is further specifically:
when only one group of water chilling units operates, no load shedding judgment is carried out; when the water chilling unit is more than or equal to the two groups of water chilling units, load shedding judgment is carried out;
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the return water temperature is detected to be reduced by the second temperature sensor, when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of the single water chilling unit, if the reduced load is smaller than a second set value and K2 is larger than a second threshold value, a group of refrigerating units are closed;
wherein: k2 = (chet.stp-CHET)/0.005; CHET is the return water temperature; chet.stp is the set point for the return water temperature.
4. A method for controlling an adder-subtractor of a refrigeration unit according to claim 1 or 3, wherein said turning off a refrigeration unit comprises: the refrigeration unit with the longest continuous operation time is turned off.
5. The control system of the addition and subtraction machine of the refrigerating unit comprises a water chilling unit and is characterized in that a first temperature sensor is arranged at a water outlet of each group of the water chilling unit, and a second temperature sensor is arranged at a water return position; comprising the following steps:
the water chiller loading control module:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the front chiller is kept to be more than or equal to the total load of the first set value percent, the second chiller is started at the moment;
and the water chilling unit load shedding control module is used for:
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the temperature of the backwater is reduced detected by the second temperature sensor, and when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of a single water chilling unit, one group of water chilling units is closed.
6. The add-drop control system of a refrigeration unit as set forth in claim 5, wherein said chiller load control module is further specifically:
when the load increases and the corresponding pressure difference at the tail end decreases, the backwater temperature increases according to the detection of the second temperature sensor, the chiller uploads the refrigeration load according to the locking temperature threshold and the capacity of self load adjustment, when the load of the current chiller rises to the total load of the first set value percent, the first sensor acquires that the chiller cannot stabilize the water outlet temperature again, the chiller considers that the running chiller cannot meet the tail end requirement, and then the other chiller needs to be started, after the delay setting time, if the load of the previous chiller is kept to be more than or equal to the total load of the first set value percent, and when K1 is more than the first threshold, the second chiller is started at the moment;
wherein: k1 = (CHWT-chwt.stp)/0.005; CHWT is the outlet water temperature; chwt.stp is the outlet water temperature set point.
7. The chiller unit load shedding control system of claim 5, wherein the chiller unit load shedding control module is further specifically configured to:
when only one group of water chilling units operates, no load shedding judgment is carried out; when the water chilling unit is more than or equal to the two groups of water chilling units, load shedding judgment is carried out;
when the load of the water chilling unit becomes smaller, the pressure difference at the tail end is increased, the water chilling unit firstly reduces the refrigerating load of the water chilling unit according to the fact that the return water temperature is detected to be reduced by the second temperature sensor, when the reduced refrigerating capacity of the running water chilling unit reaches the maximum refrigerating capacity of the single water chilling unit, if the reduced load is smaller than a second set value and K2 is larger than a second threshold value, a group of refrigerating units are closed;
wherein: k2 = (chet.stp-CHET)/0.005; CHET is the return water temperature; chet.stp is the set point for the return water temperature.
8. The plus-minus machine control system of a refrigerating machine unit according to claim 5 or 7, wherein the turning-off of a refrigerating machine unit is specifically: the refrigeration unit with the longest continuous operation time is turned off.
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